H-point 2m5666

"Fashion dates. but logic is timeless" SIA ALEC ISSIGONIS - Vehicle archltect and designer of the BMC Mini

H-POINT The Fundamentals of Car Design

u Packaging

By Stuart Macey with Geoff Wardle

e Art Center College of Design

designstudiol..... Ili

OEDICATION Thls book is dedicated to Alf & Steve Macey.

INFO

Co-publ1shed by

Stuart Macey - [email protected] Art Center College of Design

1700 Lida Street Pasadena. CA 91103 H-POINT, The Fundamentals of Car Des1gn & Packaging Copyright ©2008 by Des1gn Studio Press Ali illustrations in this book copynght @2008 by Curb lndustnes LLC unless otherwìse noted. Ali rights reserved. No part of this publication may be reproduced, stored 1n a retrieval system or transm1tted 1n any form or by any means electronle, mechanìcal, photocopylng, recordlng or otherw1se, without the pnor wrlttcn permiss1on of the publisher, Design Studio Press. We recognize that some word s. mode l names an d designations ment1oned in this book are the property of the trademark holder. We use them for identification purposes only.

an d Des1gn StudiO Press 8577 H1guera Street Culver C1ty. CA 90232 Webs1tes: www.artcenter.edu www.deslgnstudiopress.com E-mail: [email protected]

10 9 8 7 6 5 4 3 2 1 Thc technology and processes contatned tn th1s book are generic and are not proprìetary or unique to any manufacturer cr brand.

isbn - 978-1-933492-37-7

Graphic Design: Prances Torres, Stuart Macey

LCCN: 2008940773

Printed In China First edition, Aprii 2009

ACKNOWLEOGMENTS lt is impossible to acknowledge everyone who has provided encouragement and helped develop the knowledge to complete this book. Here are some of them. The Transportation design department at Art Center College of Design in Pasadena, past ard present, specifi· cally Ken Okuyama, Stewart Reed and John Krsteski. Special thanks to Geoff Wardle for his on this project and to the trans students who have been a huge inspirat1on. The Design Office team at Chrysler in Detroit and Southern California, past and present. With special thanks to: Phll Gavie, Doug Stafford, The Viper Team, Ernie Barry, Bob Hubbach, Mlke Castiglione, Akino Tsuchiya, Mark Moushegian, Alan Barrington, Ron Kyzinski, lvo Mllosavlevski , Jordan Meadows. Bryan Nesbitt, Freeman Thomas and Ralph Gilles. The design and engineering teams at Porsche in Weisach. Daf Trucks in Eindhoven. Volvo in Gothenborg and IAD in England. Also to the guys at Vosper Thorneyc·oft in Portsmouth, especially Alan Cornish and dad's best mate, Sam Bailey. Special thanks a Iso to the Society of Automotive Engineers (SAE) an d thelr associates for devetoping the tools and methods that we use every day to package cars and trucks. A huge thanks to my family: Gillian, Alan, Victoria, Haley and Shlrley far your patience and . Finaliy, the great vehicle architects, lnventors and industriallsts who have created the design icons that we know and lave, namely: Gottlieb Daimler, Cari Benz, Ferdinand and Ferry Porsche. Erwin Komenda, Henry Ford, Ettore and Jean Bugatti, Paul Jaray, Gerald Palmer, Sir Alec lssigonis, Dante Giacosa, Rudolf Hruska, Colin Chapman, Sir William lyons, Enzo Ferrari, Jim Hall, and Gordon Murray to name just a few.

CONTENTS

FOREWORD

by Ralph Gllles & Freeman Thomas

INTROOUCTION

B IO

Book lntroduction History of Vehicle Architect\Xe In Des1gn

Chapter 01 l GEITING STARTEO

20

Design Process Overview Systems & Market Segments Anatomy of the Package Quick SteJ>-by-Step Process Sections Grid & Ground Lines Main Package Hard Pomts Package Logic Drawings

Chapter 02

l FUNCTIDNS 6 SEGMENTS

46

Setting Functional Objectives Market Segments

Chapter 03

l PACKAGE IOEATIDN

so

Sketch1ng Conceptual Packages

Chapter 04

l SIZE 6 PROPORTIDN

70

lntroduction to Size & Proportion Setting Up the Length, Width & Height Key Dimensions Product Benchmarking

Chapter OS

l OCCUPANT PACKAGING

86

l INTERIDRS 6

96

Occupant Manikin lntroduction Manikin Anatomy Man1km & Occupant EnVIronment Set-Up

Chapter 06

lntroduction To lntcrior System lnstrument & Contro! 3asic Set-Up Seat Design lnterior Volumes & Cargo Storage

CARGO

Chapter 07

l POWEATAAINS

114

l WHEELS 6 TIRES

136

Powertrain Anatomy Selectmg a Powertrain Layouts & Configurations Fuel Storage

Chapter 08

nre and Wheel Srze Brake Packaging Tire Envelopes & Spare Packaging Wheel-to-Body Relatio1ships Steering

Chapter 09

l SUSPENSION 6 CHASSIS

ISO

Suspension lntroductron Suspension Systems

Chapter IO

l BOOIES

164

Type of Structures and Load Paths Crash Regulatrons Materials Closures, Apertures a'ld Vision Studles Designrng with Sectrons Aerodynamics Basrcs Ughtrng, Bumpers & Glazmg License Plates

MOBILITY

204

lntroduction

DESIGN EXERCISES

208

Ten Exercises to Help Build a Package

ABOUT THE' AUTHOAS

218

GLOSSAAY

220

INOEX

222

FOREWORD The first time l met Stuart his legs were sticking out from under a prototype Minivan. He was literally underneath the va n looking fora way to make the seats fold into the .floor. Sue h is his curiosity and deep dedication to problem solving. Stu is the kind of packaglng engineer that has an exceptional respect for design. Being an accompHshed designer himself he has always recognized that the art of packaging is the great facilitator and ultimately, in t he hands of the skilled designer, it ìs the great differentiator. As a designer l am a firm believer that proportions are •everything." They are a Iso deeply rooted in nature and our psyche. Much like how a child responds to a cute stuffed animai we respond to well sorted designs. Appeallng designs are the direct bl-product of great proportions. Great proportions are the results of judicious packaglng work. However, there is no such thing as the perfect car as every car is a compromise in some way. Great package work aims to minimize that compromise and allows the visionary designer and englneers as much freedom of design as possible. Each vehlcle design has its misslon, whether to maximize interi or volume for occupants orto achieve exceptional on track performance or perhaps even to cheat the wind to achieve the best fuel economy possible. Artful packaging 1s the calculated rationing of these distinctive compromises. Great designers ca n manipulate this ba lance of compromi:;es in their favor to create designs t hat provoke and tltìllate the senses, often creatmg an lconic product that punctuates the epoch In the process. What enables these iconic designs is lndeed the true mastery of packaglng. As most vehicles are commerciai products that must be relevant to the masses, great packaging can give a vehicle a much deeper well of greatness. A vehicle with thoughtful an d practical solutions will 3lways have greater staying power. lt is up to the astute leadership of the tirm and the design visionary t o tune this balance of art, business and the forces of the practical consumer. Design ca n be a victim of flawed packaging as easily as it ca n be glorified by lt. Needless to say, the art of automotive design has momentarily matured. Most packages are being regurgitated over multiple decades and the realities of physics and the wìnd tunnels are pushlng design into a collective corner. The savior comes within our times. We are on the brink of a brave new world of design where once again the components benearh the skin are changing in dramatic ways. With the fundamenta l change in system components comes the promise of new proportions enab ed by creative packaging. New propulsion systems components will allow us newfound design treedom that will certainly have a profound effect on the style of

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automobiles yet to be penned. We are an ever evolving species, yet our core needs and instincts rema in some· what constant in the end. As far as the business end of design is concerned. humans wlll always respond to provocative yet sensibly executed designs. This balance of the sensible and the provocative is what the art of packaging enables. This book is a lifelong dream of Stu's and the dlrect byproduct of his ion for the automobile and the fascinating process of its creation. He manages to demystify the design process in a way that wlll allow aspiring designers to benefit immediately from what amounts to a career's worth of knowledge. Not only is the book artfully done. lt is truly substantive and gives the student designer unprecedented access to the lnner sanctum of vehicle design. Thìs book is full of extremely helpful ins1ghts that help the aspinng designer grasp the fundamentals of good design. This exceptional amount of information comes together to become an essential tool in the toolbox of an aspir· ing designer. In other words, it is the decisive bible of automobile packaging.

AALPH GILLES - Vice President of Design. Chrysler Motors

Vehicle design is not pragmatic, it is an art, a rebellious act that must a iso work and function. Stuart and Geoff have created "the guide" to help every designer and engineer find "the magie" that makes each vehicle design and architecture unique, and come alive in the studi:>. Certain vehicles have a stance, a look and proporti ons that tell an asplring story that creates deslrability and an identity. lt's the ''mojo" that no one seems t o be able to explainl Read every word and every page of H-POINT; The Fundamentals of Car Design & Packaging and l guarantee it wìll give you the secrets to findlng "the magici''

FREEMAN THOMAS - Design Director. Ford Advanced Design

H-POINT

l9

INTRODUCTION In 2002, the Transportation Design Department at Art Center College of Des1gn in Pasadena, Califorma set out to re-focus their vehicle architecture education program. The goal was to help the undergraduate transportationdesign students prepare for an automotive industry that was putting greater demands on their design studio teams in a global landscape that was becoming more competitive and complex. The challenge to the faculty was to develop a syllabus which reflected the rea l world advanced concept development process and the class with materia! that would be palatable to the students who were already in a very challenging educational program. After severa l years of development, these notes have been assembled to create H-POINT. We have tried to pull together just the right amount of information an d present it in a form that ca n be digested by even the most sleep deprived design student. Fortunately. much of a vehicle's exterior design can be established around a few of the major systems, so at the advanced stages of a project many components can be left out of the package to reduce its complexity. This has enabled us to boil the subject down. not having to descrlbe every component in great detail, but rather :o focus on only the key elements that influence the exterior and interior advanced design. Car design can be a chicken-and-egg process, with the concept bemg driven by either design (emotion) or the package (logic). ldeally both are developed harmoniously to result in a pure and rational product. T'le processes used to develop concepts continually evolve as new tools emerge and the products become more and more complex, so the information contained in the followlng chapters is very generic and can be applied in any design studio environment. Packaging, or setting up the vehicle architecture, has always been a fundamental element in the creation of a successful product, which is why the main objective here is to empower designers to be part of the packagedevelopment process from day one. Hlstory is full of examples of vehicles with groundbreaklng oesigns which were driven by an Innovative package. Cars like the Chrysler Airflow, VW Beetle, Jeep Wrangler, BMC Mini and the Mclaren Fl. for example, ali pushed automotive design forward in their own way and stili influence car design today. Hopefully, this book will help you create the next historic icon.

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l H-POINT

The main objective for the advanced concept model is to develop form, proportion and architecture that pushes beyond current boundaries. To help the process flow, many important components are left out of the init ial stud· ies. Although this usually leads to a less than 100% production feasible package, the architecture should be close enough to the final solution that the concept's character ìs not lost after production engineering IS complete.

H-POINT

I li

A BRIEF HISTDRY OF VEHICLE ARCHITECTURE Probably the best way to understand the role of packaging in thc design process is to look at how and why vehicle proportions have over ti me. The next few pages previde a concise overview of some of the key milestone vehicles from 140 years of automot1ve h1story and the events that mfluenced them. Note that many ot the timeless cars and trucks shown were created entirely by treìr archìtects, but when styling or emohon became the driving factor for the concepts, the1r lifespan was ofter short. N1cholas Otto is given credìt for mventìng the four-stroke internai combustion (I.C.) engine in 1B76. This turned out to beone of the most significant inventions 1n the history of mankind. lts location. size, configuration and orientation have always had a major effect on a vehicle's exterior proportìons. Many of the early cars had simple two-cylinder engines. but as customers demanded more power the l. C. en· gine developed rapidly. The first six-cylinder appeared in 1902 followed by a VB in 1903. Cadillac built a \'12 m 1909 and started to mass produce a 70hp VB in 1915. Th1s became the benchmark motor in the USA for many years. In 1912, Cadillac also lntrocuced the starter motor made by Delco. Th1s helped to gìve the internai combusuon en· gine a clear advantage over steam and electric power plants, which had until then dominated early automobiles.

Major inventions. events & cultura! changes that have affected vehicle architecture.

4000 BC The Wheel (Mesapotainial

12

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ms

1976

Industriai Revolution IEngland

Four-Stroke Engine Niclaus Otto (l

IBBB 1--

Pneumatlc Tlre Ounlop IEnglandl

r---

THE FIRST MOTOR CAR

FRONT-ENGINE LAYDUT

ALTERNATIVE PROPULSION

Go:tlelb Daimler is generally credited with creating the first vehicle powered by an internai combusti an engine. Many early cars were adapted from horsedrawn carriages and had the same body and chassis architecture as well as a similar occupant package. Cari Benz's "Motor Car• was an cxception ond had a new package, from the ground up.

Panhard-Levassor made some great strides in the early years of automobile design. They were the first to piace the engine In the front of the car and llnk it to the rear wheels through a clutch and multlspeed transmission. The Panrard-Levassor Company was onc of thc lorgcst auto componies beforc WW l.

Electric and steam cars were in the majority inthe US at the early part of the 20th century. Com pani es like Baker, Woods and Detroit Electrlc developed electric vehicles that were clean, rellable and easy to start. In Europe, Prof. Ferdinand Porsche was developing electric and hybrid vehicles for Lohne. Steam technology was mature at this time and cars made by Doble and Stanley were aIso quite successful.

1886

1891

1908

OAIMLER MOTOA CARAIAGE II

PANHARO-LEVASSO R l )

BAKER ELECTR IC (USAI

Thls is probab/y one of the first examples of an automoUve designer stuck with the paradigms of the past. lt was ca/led the motor carriage and that's exact/y how ft was configured.

-

1893 Diesel Engine Rudolf OieseiiJ

1894 1--

Prop Shaft Renault Il

The power. range and lower cast of /.C. engines soon made e/ecric cars uncompetitive. lronica/ly, the in· troduction of the electric starter motor in 1912 finished them off.

At this time. many other cars added faux hoods to copy the sty/e of the European Panhards. Significantly, mi/1/ons of luxury cars and trucks today are bui/t wìth this sa me basic component layout.

1899 f--

Steering Wheel Packard l USAI

1900 f--

Steel Frame Mercedes Il

1903 f--

First Flight Wright Brothers (USAI

-

H-POINT 113

MASS PROOUCTIDN

UNIBDDY CONSTRUCTIDN

ART E1 SCIENCE

Henry Ford set out to democratlze the automobile, by reducing the price of a car and raising wages through mass production. The Ford factory produced one Mode l T every three minutes. They were ali painted black because that was the only color that would dry quickly enough to keep up with the production line.

This Lancia was a revolutonary car far the early 1 920s, and the first car with a load-bearing unibody (monocoque). Other nnovations lncluded independent front suspension with coil springs and a narrow 13°, V4 aluminum engine with a single overhead cam.

Ettore Bugatti was nat only a great designer but also a orilliant vehicle architect who, along with his son Jean, were respansible far some af the most beautiful cars in history. Ettore had the unique ability ta design structure empathically, without stress calculations. The Type 35 is stili one of the most appealing and successful race cars af ali t ime.

1912 MODEL T l USAI

1922 LANCIA LAMBOA IITALYJ

1922 BUGATII TYPE 3S !)

With annua/ vehicle sa/es today of over 60 m/1/ion, /t /ooks like M r. Ford succeeded. The design of cars today is often influenced by the complexity and investment of high-volume mass production.

The vast ma}ority of er.ger cars and vans today are bui/t with a frame/ess unibody structure and independent suspension.

Today, computer systems can aid designers to create organic structures which are fully optimized and often naturally beautiful.

1905

-

SAE Formed !USAI

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l H-POINT

l Sia 1--

Starter Motor lntroduced Oelco !USA)

1914 1--

Automatlc Trensmission Mercedes (l

1914 -1918 t--

World w ar l

19aa 1--

Synchromesh Gears Cadillac !USAI

1--

-

AERODYNAMICS & CAB FORWARD

THE PEOPLE'S CAR

THE 4x4

lnspìred by aerodynamic forms created by the Hungarian Paul Jaray, the revolut1onary Airflow package pushed the occupants forward to the mìddle of the wheelbase. lt was also one of lhe fi rst US ::>roductlon cars to adopt unlbody construction.

Probably one of the best known cars of ali time. ìt was origìnally designed before WW Il, by Prof Ferdlnand Porsche wìth sponsorship from Adolf Hitler. Much of ìts archit ecture was by the Czechoslovakian latra T87. The rear engine (flat four) " people's car'· was mass produced between 1938-2003, selling over 21 million units.

Orlgìnally designed by Wlllys Overland in 1939 t o carry four people--or two with a stretcher-over the rough terraln of war-torn Europe. The Cltizen Jeep (CJJ was produced for c1vllian use after WW Il. Th1s was the first purpose-bullt 4x4 SUV. Updated vers1ons wlth s1m11ar architecture are stili manufactured today and it has become a design lcon.

1934 CHRYSLEA AIRFLOW !USAI

1938 [451 VW BEETLE I J

1945 JEEP WILLIES ICJJ l USAI

The Alrftow's advanced design was too radica/ for the market and was a disaster, almost bankrupting Ch rysler. But after the initial design shock had ed, both Ford and GM adopted this fo.·m and architecture and were very successful with ir.

Many other vehicles were bui/t on its platform and although very successful in its own rlght. /t /s worth noting that the Beetle has had littie lnfluence on cars today. lts architecture was effectively a blind al/ey.

The design, proportions and basic archltecture are based on pure Jogic and have remalned almost the same for over 65 years. The seven-slot grill and headlight layout a/so became the Jeep brand logo. The originai Land Rovers were insplred by and designed from che earfy Jeeps.

1928 Rrst Freeway Rome lltalyl

1929 Stoclc Marlcet Crash \Vali Street l USAI

t--

1937 GM Styllng Dlvlslon Harley EariiUSAI

t--

1939 First TV Broadcast !USAI

t--

1939 -1945 World War Il

l---

H·POI'I ( 15

THE PICKUP TRUCK

DESIGN WITH IDN

ENGER PAIDRITY

The DNA for pickup trucks can be traced back to the 19th century, but the Ford F150 has held the ti· tle of best-sellìng vehicle In the USA (and the world) for 20 years. lts archltecture is stili very sim1lar to the or ginal F1 w1th ìts body and bed mounted on a durabte steet frame. The tongltudlnat front engine RWD/4WD powertrain and solìd rear axle/leaf spring suspension layout aIso remai n the sa me.

The '50s & '60s were glori::>us years for the US automobile industry. Fueled by cheap abundant gas, a strong economy, the baby boom and post war optimJsm. the cars of this er:t grew to be enormous. flamboyant and 1deal for customizing. lt •s sai d that the d1fference between European and American cars In this era was "A fcot of styling." What followed in t he '70s was not pretty.

Sir Atee lssigonis was asked t o create a respectable small car to help Britain get through the Suez oil crlsls. His answer was the Mini, which remained ln production for 40 years, selling over 5 mìlllon cars. The transverse engine w1th FWD and 10-inch whccls crcated a ·enger priority" package wh1ch has been adopted by almost every high-volume car manufacturer m the world.

)

ft 1948

1956

19S9

FORO Fl TRUCK !USAI

CHEVROLET BEL AIA (USAI

BMC MINI IENGLANOI

Truck architecture ìs another example of design baseo on Jogic. Today's trucks are becoming more luxurìous and are used more as /ifesty/e vehic/es. Crossover and derivative SUVs are often based on truck platforms.

The US design studios simp/y could not react qwckly enough to downsize their concepts during the oil crisis of the early 1970s. They /ost a huge amount of market share to smaller, more efflcient imports. DomestiC market share has s/nce dropped from 95% in the ·70s to less than 50% today.

Probably one of the most mfluentìal cars of ali lime. its innovative package layout can be seen in hundreds of millions of vehìcles worldwide. Because of its relative complexity, the Mini made almost no profit for the manufacturer, but the advanced archi· tecture allowed /ssigonìs to design an exterior whlch instanlly dated BMC's other cars.

1945 Atomic 8omb Oropped IJapant

16

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H· POINT

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1948 State of lsrael recognlzed IMiddle Eastl

-

1956 Olsneytand Opens (California - USAI

-

1956 Htghway Act (USAI

-

1956 Suez 011 Crisis IEnglandl

-

-

MID-ENGINE LAYDUT

THE BRITISH ROADSTER

THE LUXURY SUV

Charles & John Cooper entered thetr underpowered Formula 2 T45 in the 1958 Argentine F1 Grand Prix and won. This was the flrst car to win a GP with mid-rear engine layout which helped to create a more balanced and aerodynamlc race car. The Cooper Climax T51 won the world champtonships m 1959 & 1960 and no front-engine cars have won an F1 race since then.

Colln Chapman was a very mnovative lightwetghtsports-<:ar architect who designed severa! classic tcons. The Elan deflned the small British roadster architecture. lt weighed 590kg wlth a short 84" (2135mm) wheelbase. The small longitudinal front 1500cc eng1ne drove the rear wheels and Chat:r man utillzed the prop shatt tunnel as a "backbone· for the body structure.

The first fully off-road capable luxury SUV The Wagoneer was the inspiration for the very successful Range Rover in 1970 and many other models that followed. lncluding the 1984 Jeep Cherokee with a unlbody. lnitiolly, luxury SUVs rrcscntcd only a small percentage of the market, but today they sell m very h1gh volumes and earn large profits for the1r manufacturers. Their main drawback is fuel consumption.

1959 CDDPER CLIMAX TSI IENGLANDJ

1962 LOTUS ELAN IENGLANOI

1963 JEEP WAGDNEER (USAI

The Benz & Auto Union race cars of the 1920s & '30s were the first mid-rear engine cars, but the Coopers were the first to win races because of their Jayout. rat.'1er than brute force. Today, the mid-engine layout fs the slgnature for most European supercars.

Many of today's sma/1 roadsters are based on the Elan's ph/Josophy but are usually larger to provide space fora more generoJs occupant package, a more powerful engine and a crashworthy body structure.

To meet their originai functional requlrements, the arcnltecture requires a very high floor and seating positlon. This provides owners with a sense of security and status. Most SUVs are so/d for theìr ìmage, not theìr functiona/ity.

1960 Beatles Formed IEnglandl

1--

ISSI Beach Boys Formed (California - USI

-

1961 First Man in Space Yuri Gagarin lUSSAI

1--

1963 SEMA founded !USAI

1965-1975 f--

Vletnam War

H-PONT

l 17

DOWN FORCE

THE HATCHBACK

THE MINIVAN

Desigred by Jrm Hall. the Chapparel was the first racìng car to employ a large wrng to create down force to increase traction without adding mass. Although much about aerodynamlcs and vehicle dynamics was known after WW Il, lt took at least 20 years to apply the Knowledge.

The Golf was not the first hatchback. That honor goes to a version of the 1954 Citroen Tractron Avant. lt also owes much of ìts proportrons to the 1971 Alfa Romeo Alfasud {also designed by Glugiaro). However, the Golf helped to define the formula for the perfect European ramlly-sJzed hatchback. The GTI vers1ons also helped to define the "Hot Hatch" market.

The thought of driving a minivan with imitation wood claddrng sends a shudder down the sprne of any young designer. However, the FWD, car·based architecture of the Chrysler Minivans was a stroke of genlus, providing Americans with JUStlfication to once agé:lin drive largtl Vt!hicle:s IJecèluSe lllese were efficrent.

1965

1975

198S

CHAPPAREL !USAI

VW GOLF I I

CHRYSLER MINIVAN !USAI

The lesson to be Jearned from thìs car is that some quite obvious solutions may take a whlle to become obvious to everyone. There are stili plenty of inventlons waitìng to be realized.

Hatchbacks are a stap /e of the European markets where many people can only afford one sma/1 car whìch has to serve many functions, includlng being easy to park.

Ford and GM simp/y downsized therr fu/1-slze vans with "on frame• body construction and RWD, whlch made them inefflcien t. Chrysler's enger prlor ity, unibody, and FWD architecture (like the Mini) changed the global minivan market forever. increasing sa/es by millions of units.

1573

1565

-

Flrst Moon Wallc INeil Armstrong -USAI

18

l

·POINT

r--

Oil Crisls IDPECI

1586- 1588

r--

FJ Turbo Era

l Europei

-

198!1

Berlin Wall Falls Il

-

199 0

Gulf War IMiddle East l

-

NEW MICRO CARS

X X LARGE

The Smart car was designed specifically to offer safe, inexpensive, easy-to-park commuter transportation for two people. lts very short overall length ls made possìble by the 660cc engine that is packaged under the rear floor, a very strong "Tridion· body structure and a single row of seats. The ForTwo also fits into the Japanese "Kei" car segment which offers tax incentives to small, lowpowered cars.

In the last year (2006) of the H1's production, lt sold only a few hundred units. Although it was a specialist vehicle, it reset the bar far the slze of large personal vehicles. lts originai success in the US market was due to the role it played in the first Gulf war ln 1990. With gas consumption around 10-12 mpg, it is not only great for helping to liberate oìl-rich countries but also ideai for taklng the kids to school in Detroit.

1990

-

NEIGHBORHOOO ELECTRIC VEHICLES US legislation allows certain types of veh1cles to drive on public roads (35mph speed limit) wlthout having to federai crash tests. This helps to reduce weight, cost and lnvestment allowing NEVs to proliferate. The Gem seats 4 engers, has a top speed of 25mph, a range of 30-40 miles and is very quiet. Most families own severa! different vehicles and the GEM helps to offset the cost and fuel consumption of larger cars.

1998

1992

SMAAT FOATWO (I

HUMMER Hl (USAI

GEME4 lUSAI

fronically, perpendlcufar "nose flrst " parking is l/lega/ in most European cities, so the Smarc is unabfe to help so/ve chronic parkfng issues. Thls high/lghts the need for totaf transportatlon sofutions. Significantly, the Smart is now so/d in the USA.

The average weight ot vehfcles is now much higher than it was in che '60s, mainly due to stricter crash requirements, improved performance and larger interior volumes. Many people a/so want to feel more secure whfle driving.

Legislation and infrastructure p/ay a big ro1e in vehicfe design. Today, many communities are growing up with provisions for neighborhood electric vehicles (NEVs) to help improve the quafity of /ife For residents by reducing emissìons. no/se and anti-social driving habits.

ISSI WorldWideWeb

-

1596 Google Founded

!USAI

-

BODI Flrst IPod

(USAI

-

eOOI 9.11

!USAI

r--

13003 War an Terror (Middle Eastl

H- POINT 119

THE ADVANCED CONCEPT DESIGN PRDCESS This stage usually takes 6 months to a year to complete. This mindset is differ· ent than the product1on phase, much tooser and more progressive.

The process starts w1th researching the intended markets. customers and competition. Emerging technology and manufactunng strategies are also studied.

The bas1c layout of the maja- components and any innovative features are sketched loosely 1n various contiguratiOns.

Primary goals for the project are set. These should be considered from both the customer and manufacturer's perspective.

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Once the basic dìmensions and hard points for the concept are formulated, the scale or full-size clay model1s built and developed with the package.

Existing products with similar attributes are compared to validate the design direction. This process is used to establish the basic proportions.

THE PRODUCTION DESIGN PROCESS This can be a three- or four-year timeline wrth usuatly one year In the studio. The fìnal product must be 100% feasible, meeting ali reqUirements for manufacturing and marketing.

PROOUCTION DESIGN

PROOUCTION ENGINEERING

PROTOTYPE BUlLO. TESTING & LAUNCH

The advanced concept is handed to a productlon-design team. This group will develop the extenor and interior surfaces over a package t1at is 100% feasible for product1on and meets ali of the cost targets. as well as the needs of the intended markets. After testmg, a few minor des1gn changes may be required.

H-POIN-

l 23

SYSTEMS Every package is comprised of the same group of systems (illustrated below). Each of these systems will vary greatly according to the functional objectives of the vehicle. Also. note that each of the components that make up the different systems ìs packaged wìthin a spatìal envelope, whìch allows for motìon, manufacturing tolerances, clearances, heat insulation, maintenance and assembly.

OCCUPANTS

WHEELS G TIRES

24

l H-POINT

INTERIORS Eì CARGO

SUSPENSION G CHASSIS

PDWERTRAIN

BODY

VEHICLE TYPES 6 MARKET SEGMENTS At some point earty in the design process. it should be decided which market segment the concept will be designed for. Quite frequently, a multi-functional concept ls designed and will crossover to more than one segment. The market segment or vehicle type is often determined before the project 1s started. helping to focus the design team in a specific direction. Fora "blue sky" proJect. the customer requirements may be the only consideratlon during the ideation phase and a market segment associated later. T1e latter approach can help to break paradigms associated with certain vehlcle types.

'

---7-1

MICAO CARS

MINIVANS

ECONOMY CARS

suvs

LUXURY CARS

PICKUP TRUCKS

SPECIALTY CARS

COMMERCIAL VANS

H-POIN

l 25

ANATOMY OF THE ENGER CAR PACKAGE The elements in the package will vary from concept to concept, but the items shown In these illustrations feature in most vehicles. Each of these elements will need to be studred by the studio engineerrng team during the development of the project to provide a high level of confidence in the vehicle's design.

driver manikin

b pillar

windshield header rear occupant manikins instrument pane!

rear header

windshìeld

trunk

powertrain

rear lighting

forward lìghting

tire diameters 6 proftles

cooling aperture front bumper S impact system

impact system spare tire

approach angle

departure angle

front spindle G suspension floor Ei underbody structure

ground clearance S ramp aver angle 26

l H-POlNT

rear spindle & suspension fueltank "curb" ground line

UNIQUE. VEHICLE- SPECIFIC FEATURES

PICKUP TRUCKS

roof 6 roof systems

frame

roof rail IIft gate l hatch

side glass

doors 6 door aptertures HATCHBACKS

convertible top

sili floor 6 underbody structure

CONVERTIBLES H POIN

l 87

STEP-BY-STEP PROCESS The initial package should be kept as simple as posslble. Only a few elements are needed to set up the basic exterior hard points. Just like a design ideation sketch, do not try to Include every detail or solve every problem. The main objectlve ls to get started.

adjustments as the concept develops. Always be sure to reference the functional objectives that are driving the architecture. Usually, if you stlck to sound logic, the package is quite simple to build and you will be able to defend the layout if it ls ever challenged.

Fortunately, the bulk of a vehlcle's proportlons are established by only a few elements: the occupants, powertrain, tires. cargo storage, ground clearance and crash protection systems. These ca n be put together in a logica l order, but expect to lterate the design continually. Try to think about which components will drive t he package and whlch will be subordinate and why.

The examples, o n the fo llowing ni ne pages, show how different types of vehicles can be approached with the same fundamental process even though they require totally different package solutions. Before creating the package geometry,loosely sketch out the package and arrange the major components based on the functional objectives.

As each system is added, it is going to affect the elements already located in the package, so do not be afraid to start piecing the package together and making

28

J

H-PDINT

STEP l PACKAGE G DESIGN IDEATIDN Loosely sketch out severa l package concepts based on the functional objectives. Include layouts of the occupants, cargo, powertrain, wheels and fue l. Also, think about the body structure tlnd r. losurP.s (doors) an d any other special features t hat may lnfluence the package.

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Batteries + Controllers 112kWhl si.U Stl'uctur-e

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H-POINT

l 29

STEP 2 SET UP THE DRIVER'S HEIGHT &PDSTURE Start by positioning the driver using the SAE 95th percentìle manikin. Establish the heel height fram the ground and then the seating pasture. Consider the ground clearance and underbody structure when posltianlng the heel palnts. Before settlng up the seating pasture, thìnk about the followlng: downv.ard visibility, command-of-the-road seating (eye point from ground), center of gravity, mgress;egress and aerodynamics. Probably the best way ta get the driver lacatian close is ta look at existing vehicles with the same attrlbutes and benchmark them. See Chapter 4 for more information on benchmarking.

30

l H-POINT

STEP 3 SET UP THE REAR OCCUPANTS Add the rear occupants if there are any. Again, use a 95th percentile manikin with consideration for leg room and "theater·· seating, if appropriate, to give the rear beller forward Note that some specialty cars, such as coupes or very small sedans will not fully accommodate a 95th percentile manikin in the rea r. With both manikins placed, establish a spaclal envelope around them and develop visibility goals. Look at the effective headroom and shoulder room first, then look at the up and down angles through the windshield apertures. Any other important relationships to the occupants should be noted at this stage.

l

_)

H-PDINT

l 31

STEP 4 SELECT ANO INSTALL THE PDWEATAAIN Select and positlon the powertrain (engine. transmission and final drive). The choice of system may have a dramatic effect on the proportions. Choose it based on the amount and type of power requlred and aiso think about which wheels will be used to feed the power lo Lhe ground. See Chapter 7 for more information on powertrain packaging.

32

l

H-POINT

STEP S SET UP THE OCCUPANTS' LATERAL LDCATION After the powertrain is posrtioned, set up the latera! posit1on of the occupants. Cons1der the overall width lim1tation and the interior environment expectations for the type of vehicle you are des1gmng. The locatron of the manikins moy olso be affected by the powertrain, aerodynamics, enger ·through and threeacross seatlng.

o

o

H·POINT

l 33

STEP 6 CREATE SPACE FOR THE CARGO The cargo space may be designed around speciftc objects or a volume target. look to create a nexible interior environment with folding seats and bulkheads. Weieht will i'll!'io he i'l c:onsic1eration nnc1 this may affect the location and other el e· ments in the archltecture such as the body str Jcture and suspension. Refer to Chapter 6 for more information on cargo packaging.

34

l '-i-POINT

STEP 7 SIZE & POSITION THE IPAIMAAYJ OAIVEN WHEEL Determine the size of the wheel and tire package and locate the spindles of the driven wheels relat1ve to the occupants and powertrain. Study the packages below and note the relationship of these elements. They will difer greatly dependmg on the powertraìn ayout. See Chapter 8 for mformatìon on wheel & tire choice and set up.

)

) 35

STEP 8 ESTABLISH THE WHEELBASE The locatlon ofthe other wheeljaxle will depend on weight distrlbutiOn or package efficlency. For smaller economy cars, the wheels will be as close to the occupants as possible. For high·performance or luxury cars, the wheelbase will be set up to improve handling or comfort. Trucks and commerciai vehicles need to piace the wheels under the cargo area, to limit the effects on the steering when the vehicle is loaded. See Chapter 4 on size and proportion to help set up the wheelbase.

36

l H·POINT

STEP 9

STEP IO

SET UP THE FRONT 6 REAR TRACKS

CREATE THE BODY ANO INTERIOR TRIM SECTIONS

Although deslgners usually prefer the wheels to be as far outboard as possible, the track will be limited by the veh1cle w1dth target. The occupant package, cargo requirement s or handllng targets may al so push the wheels outboard.

Develop the body and interior sections throughout the package. The body struc ture, door configurations and rnterior des1gn willlnfluence the exterior surface. See Chapters 6 & 10 for more information on body archftecture and interìors.

See Chapters 4, 6 & 9 to understand some of the factors that govern the track.

o o

o H -POIN

l

':J7

DEG WITH SECTIONS The bulk of the advanced package and the body is developed in five "Sectional Views" (multiple sect1ons in one view) which are cut through the major elements ofthe package-i.e., the hip points (H-points). spindles, powertrain, fuel tank and the cargo compartment. As the package progresses, more sect1ons Wlll be created around the vehicle, but to get the initial concept started, it is important to keep the studies as simple as possible.

The ma1n objective here is to establish some of the mai n hard points, so that the exterior design can be modeled aver the key elements of the package, developing the body structure as each section ls constructed. Every type of vehicle has special requirements and the location of the sections may vary. The engine may be In rhe rear or under the floor far some cars. For example, pickup trucks will need to be designed around the bed and the cab.

SECTIDNAL VIEW A- A This sectlonal side view is cut through the centerline of the body and the occupants. The other elements are shown to create a "picture" of the lnltial package layout.

38

l H-POINT

SECTIONAL VIEW A- A SECTIONAL VIEW E-E

SECTIONAL VIEW 8- 8

The five main sectional views are cut through the major elements of the package. Because most vehicles have a lot of curvature in their surfaces, multiple sectlons are put in each v1ew to form a s1mplified picture of each zone of the package.

SECTIONAL VIEW 0-0

For example. in the side-vlew section A·A, the vehicle ou11ine is shown at the YO (Y zero)* centerline. The occupants are also shown in this view wlth a section through the headliner at the occupant centerline. The headroom is cross-referenced and accurately illustrated in the rear-view sections.

SECTIONAL VIEW C-C

*The Y-grld piane runs a long the centerline of the ca r. Anything on-center ls therefore located at YO.

SECTIONAL VIEW 8- 8

SECTIONAL VIEW C-C

SECTIONAL VIEW 0- 0

SECTIONAL VIEW E-E

Cut through the front spinriles "nd engine, this section ls used to help prove out the front suspension and engine package under the hood and fenders.

Cut throueh the front occupants' H-points and head contours, this key section is created to set up the door s, s1de glass and roof-rail sections. Other elements like the roof over the head environment, sills, floor and underbody structure are arso included here.

Cut throueh the rear occupants. this is similar to the sectlon through the front occupants but here the fuel tank is often 1ncluded under the rear seat.

Cut through the rear spindles. this shows the cargo bay and the rear suspension system. Other items such as the exhaust system and spare tire may also be featured. H-POINT

l 39

GAIO PLANES ILINESI SAE Jl83 The package is buìlt in a 100mm three-dimensional grid which becomes the master vehicle grid system throughout the project's life. This XYZ grid is created by the ntersections of a series of horizontal, tongitudinal and latera! planes. The grid reference system is used as a reference between the CAD (computer-aided design'! models (or drawmgs) and the clay models. The location of the vehicle compo:1cnts ond scction cutting piDnes are also referenced to the grid.

1-.---vehicle centerHne

Y=O

r-.- EXAMPLE:

The enger is located at Y 365 (365mm from center).

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X GRIOS ILONGITUOINAL

GAIO DRIGIN PDINT

40

l H-POINT

UCURB" GROUNO UNE

[

X=D y =O Z=D

Y GRIDS ILATERALI

The GRID ORIGIN POINT should be located out in front of t he bumper an d below t he ground. Once created, il will alwdyS remain in the same piace relative to the package. lf the ground llne ls modlfled and pushed away trom the body or the front f ascia is moved forward, they will not move to a "minus'' grid coordinate.

GROUNO PLANES ILINESJ Dunng the design process. the body, powertram, occupants etc. maintaln their location In the grid system. The ground line. however, is reposit1oned according

These are illustrated below: Each requlre their own set of ground llnes There are severa! reasons to create a ground line for each condltion. Matntalnmg the

to the location of the ti re patch. {This is apposite to the real world where

requlred ground clearance is one reason. Measuring the vehicle's overall height

the vehicle moves up and down on a fixed road). Three d1fferent factors wl li cause a vanatlon In the relationship of the vehicle to t he ground line:

and step-in height is a iso a very i'l1portant factor to consider.

1. Loading {attitude)

Most veh1cles are designed and modeled at "CURB" attitude.

2. Tire size variation 3. Ride height settings

VEHICLE ATTITUDES

TIRE SIZE

RIDE HEIGHT

As the veh1cle is loaded, the ground llne will move closer to the body. The three ground l1nes or attitudes shown here .are:

Most vehicles are offered with several wheel and tire packages. Thls otten results in several different tire diameters. lf the suspenslon system ls not adjusted to each tire, the veh1cle's relat•onship to the ground will vary.

Vehicles with on-road and off-road packages will usually have two or more suspension sett ngs to improve the vehicle·s performance In lts lntended env ronment.

l. Curb- no engers. full fluids.

2. Full rated - fully loaded to the gross vehicle we1ght (GVW). 3. Full jounce -

fully compressed suspens1on.

These are the three ma in attltudes used in the design process to check that the veh1cle is meeting ali the hetght and clearance requlrements.

H-POINT

l 41

KEY HAADPOINTS A primary functìon of an automotlve studio engineer ls to feed the design team with hardpoints, which are generated from the package. The views below illustrate the main hardpoints that are required to start a clay or CAD model.

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1. SILL & FLOOR HEIGHT Determlned by the grauno clearance, the ramp-over requirements of the vehicle and the underbody structure depth. The lowest point of the vehicie is often a chassis or powertrain component.

the transmisslon wiil be a conslderation for frontwheel-drive (fWD) vehìcles. The track is determined by a combination of the distance between the front structure frame ralls and the tire turn envelope. Tire size wlll be lìmited by body size, suspension components and the vehicle's turning circle.

2. FRONT WHEEL AND TIRE The front spindle height ls determined by the static load radlus of the tire. Longìtudinally, the jounce-and-turn tire envelope will establish the distance of lhe front spindle from the dnver's foot. lt may al so be moved further forward to inftuence the we1ght distribution of the vehicle. Also, the output shaft location from

3 . CHIN HEIGHT The chin should clear a 162mmhigh parking block. A 10° approach-angle lìne (when the vehìcle ls fully loaded) ìs recommended for enger cars. Above 28° is requìred for offroad vehicles.

42

l H-POINT

4. FRONT BUMPER LOCATION For enger cars, the bumper system height must cover the "bumper band'' which ls generally mandated to be from 406mm to 508mm above the ground. The longitudinal location must previde enough crush space n front of the occupant's feet to meet high speed (40mph) frontal impact requirements. Any object which will not compress on impact-i.e., the engine. transmission. steering rack, etc.-is added to this dimension. The offset of the bumper impact surface to the body and lamps will depend on the coillsion requirements and the manufacturìng cost lìmltations of the system. To meet low-speed

impact requirements, bumpers w1th average cost and weight will reqwe about 50-70mm of offset. but it is worth benchmark.ng veh1cles with smaller offsets. For European cars, the front fasc1a profile should be shaped to meet pedestrian impact safety req01rements for that contlnenl.

tnm and a sunroof if req01red. The roof should be as low as possible to reduce weight. lower the cen· ter of gravity and miniTuze frontal area to reduce aerodynamic drag. 10. REAR ROOF A slm1lar condlt1on to the front

affects the height and horizontal locat1or of th1s point. Additional space 1S requ1red for the hood latch.ng structure.

headroom is desirable. Many vehlcles however will compromise rear headroom to allow fora lower or faster roof llne. This is common In sports coupes and in the third row of an SUV where occasionai seating is provided.

6. HOOD PROFILE lnfluenced by the position of

11. REAR HEAOER Similar to the front header.

the engine induction system (manifolds, throttle body, etc). Recent European pedestrian head 1mpact legislation has increased the •equired hood clearance to hard components. Toward the outboard edges, suspens1on towers often affect the hood height.

Hatchbacks will req01re additional structure in or der to accommodate the mounting of the rear lift gate hinges.

5 . LEADING EDGE Usually the cooling module

16. ROOF RAIL SECTION The outer skin of :he roof rail is established by a stack up of severa! inter-

nally positioned components. while providmg adequate clearance to the occupant head form. The sectlon through the rail will compnse the body·inwhlte (BI W) structure, the door trame, head impact protecllon, and trim. Addltionally, side cur.ain airbags may be packaged. The type of door construc t•on used will affect the size and shape of the roof rail section 17. SIOE GLASS Usually a radius, but occasion-

7. COWL / WINOSHIELO TOUCH DOWN The cowl height is l1mìted by hardpo1nts generated from the engine clearance envelope and driver visibility. A downward vision anglc of lcss thon 6° may be a problem for shorter drivers. Longitudinal locations are controlled by engme mamtenance access issues (forward) and prox1mity to controls (rearward) lf the w.ndsh1eld is too far from the dnver's eye point the A pìllar may affect forward vis1or. An aggressive windshield installation angle may result In d1storted vìsion (65° from the vert1cal 1s about the maxìmum. guafanteed to avoid distortion with cu•rent glass technology). 8 . WINOSHIELO OPENING & HEAOER Determined

by the head to headllner relat1onsh1p, header structure and head impact foam th1ckness. The upward vislon angle will help to set up the header location. An upward vis1on angle less than 11° 1s considered a compromise. 9. FRONT ROOF Should provide appropriate room over the manikin's head form for head clearance,

12. REAR CARGO Most vehìcles will have some

cargo storage; for sone lt is a high priorlty. The he1ght of the cargo area is governed by the size of the objects that are intended to be carried and the target storage volumes. Rearward visibihty will aIso limit the deck and bed heights 13. REAR BUMPER LOCATION Sim1lar he1ght re-

quirements to the front bumper but with add1lional consideration for loac height vanation which is greater at the rear. Rear lmpact requlrements influ. ence the rearward location of the bumper beam. The height of the fascia (bumper skin molding) will affect the lift o·Jer height ror loading cargo.

flat. The upper locanon is set up by the roof rail design and location. The offset to the roof rail section depends on how it is constrained by the door system. The lower po.nt at the belt line is positioned to provlde adequate shoulder room and ensure that the glass will drop inside the door's outer profile. 18. BELT-LINE LOCATION The he1ght and Width

can be dnven by the exterior design. but the relatlonship to the occupant should be a consideralion The height relative to the occupants can be checked against benchmark vehicles to ensure that lt is not too extreme. Adequate shoulder room should be provided to the door inner . 19. BODY SIDE PROFILE Must be designed to al-

low lhe glass surface to drop lnslde lhe door section, missing ali of the hardware and obstruct1ons w1th1n the door assembly.

14. BODY REAR LOWER (Oeparture angle). Can be

less than the approach angle. (20° for off-road vehicles). Often the lowest parts of the car beh1nd the rear wheels are the exraust system and spare t1re. 15. REAR SPINDLE The track and he1ght are set

up In a slmllar way to the front. The longitudinal locetion is normelly es closc to the reor occupont as the tire envelope will allow. In the case of a cargo truck or mimvan. weight dlstributìon will be a factor.

20. WHEEL COVERAGE Most vehicles Wlll be de-

Sig'led to meet European wheel coverage requirements. Th1s standard requires that the body work co.,ers the outboard edge of the tires in a zone betv.een a line 30" (from vertical) forwarc of the spindle and 50° rearward.

H- PDINT

l 43

PACKAGE DRAWING ANO VISUAL COMMUNICATION The ìnìtial package ìs developed accurately ìn a 3D CAD system, but as it progresses it should be clearly commun1cated to everyone involved 1n the project. This can be done effectively in a 20 graphic format. The drawmg on the opposlte page ìs an example of a typìcal package logic board. l t conta ns details about the package end the functional objectives that are driv· ing it. lts goal 1S to describe the logic behind vehicle architecture so that the design team ca n make good decisions to steer the project.

44

l

H-POINT

The main views are graphic representations of the architecture with ali of the major systems illustrated and described in detail. The vehicle dimensions are also ncluded and benchmark compansons to other veh1cles are drawn to help put the concept into context. The benchmarks also prove out the feasibility of controversia! proportions A more detaìled example of a package logic board 1s shown on pages 216-217. Benchmarking is covered on pages 82-85.

o

SAMPLE CONCEPT PACKAGE LOGIC DRAWING A Brlef Oescrlptlon of the Concept

MERC EOES ClS

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H-POINT

l 45

INTROOUCTION TO FUNCTIONAL OBJECTIVES A design team is only given one chance to start a project. One of the biggest mis· takes they ca n make is not to consider the functional objectives of their concept in enough depth early enough in the lite of the project. Every product must serve a purpose for its customer and manufacturer. These need to be thought through really well before the first Une is drawn on the pack· age or design. At first it may fee l that focusing o n this aspect of the process wlll grind a project to a halt, but the truth is the functional objectives are going to make each team member stop and think about what they are doing and approach the design with a fresh perspective. The best approach is to start with ali the right questions and not necessarily the answers. Every so often the auto industry goes through a revolution, often brought about by advances in technology, economie pressure, ecology or politica! issues. Three main areas (shown apposite) need to be considered when setting out the objectives for the project: the customer, the manufacturer, and the market or environment. These wlll drive the basic architectJre ot the project, and technology will make it work. will usually Ltlal may be physical or emotional. The customer demographics and lifestyle should be examined very carefully. lt will be difficult to understand why some elements In the architecture are desirable to a certa in customer. Classic examples of this are people who drive off-road vehlcles but never go off·road. or buy a pickup truck but never carry a load in the bed. There is obviously something else about the architecture that attracts these buyers. The environment or market the customer lives in will have a great effect on the design, which may be influenced by the climate, terrain, lnfrastructure, economy, or legislation. Thfs is significant because any given customer will need a different vehicle depending on their geographical location.

48

l H· POINT

ldeally, the manutacturer's limiting parameters should remain unnoticed by the customer. The overwhelming fact remains that automobiles are very complicated to build and require a massive lnvestment of capitai. so taking care of business will be a primary consideration for any successful designer. This often involves working withfn a budget and timeline, developing a concept that is feasible for manufacture and that fits lnto a long range strategy. The considerations described o n the apposite page represent the factors that will influence the design of a car or truck. Not ali of these apply to every vehicle but they should be thought about before crossing t hem off the list . Most specialist cars, by nature, perform well in one at the expense of another. Some functional objectives can be polarlzing leadlng to tension within the design team, making it even more important to be very clear about prioritiz· ing them. lf each team member clearly understands the functiona l object ives, difficult decisions will be easier to ra:ionalize. lnterpretlng this informalion is largely the responsibility of lhe studio engineers. Their job is to understand the physical and emotional needs of the customer, and convert them int o architecture using the most appropriate technology. They also have to understand the limitatlons of the intended markets and t he business ur U1t:! Finally, haw lo lo clearly to the rest of t he design team.

FACTORS THAT DRIVE THE FUNCTIONAL OBJECTIVES The lists below contatns the key factors that should be cons1dered before the functional objectlves are set up.

CUSTOMER FOCUSEO ATIRIBUTES

cast • image • size • interior space • cargo volume • number of engers • economy • weight • handling • speed • flexibility • comfort • durability • off-road capability • trim level• security • colors • noise/vibration/harshshness INVHI • emissions • towing capacity • customizing potential • loading capacity • aftermarket component availability • command-of-the-road seating • easy ingress/egress • maneuverability • range • sound • power • safety/crashworthiness • brand identity

MANUFACTURER'S CONSIOERATIONS manufacturing capability • manufacturing costs • product lineup • platform sharing strategy • derivatives • production volumes • dealer network • marketing strategy • manpower • paint • available components & systems • warranty • RHO/LHO

MARKET FORCES infrastructure • population density • parking • economy • taxation • insurance • ecology • culture • legislation • security • climate • consumer advocate groups • sales volumes • discrimination • infotainment

H· POitl

l 49

APPLYING OBJECTIVES TO THE ARCHITECTURE As the key factors are analyzed, specrfications and solut•ons should be listed to help bulld the package. The package illustrattons show how a few of the major elemen:s are established around the functiona l objectives.

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n

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•

•

n

•

economy • weight • handling • speed • ff road capablhty

colors • noise/vibration/harshshness (NVHJ • emissions • ....

...

•+•

customizing pot ntial • loading capacity • aftermarket component availability • brand identity • command-of-the-road seating • easy ingress/egress • maneuverability • range • sound • ........ • • safety lcrashworthiness

OR.MALOFF- R.OADTR.fA.CK

LAR-<:;6 POW6R.FUL 6N<;IN6 350 "BI-t'P MINIML-tM 350 VS' - V1.0

SO

-f:WOK.:; TOWINc::; CA'PACITy-

l H-POINT

...

MANUFACTURER'S CONSIOERATIONS

manufacture • manufacturing costs •

' ........ • platform sharing • ,............+ ...,.,

•

production volumes • dealer network •

marketing strategy • manpower • paint • available components 6 systems • warranty)

CHASSIS CA"B- § SLI,V D6R.IVATIV6S

• FvtLL-SIL6 Llct t-tT § H6Avy TR.vtCKS 1500, :LSOO, 3500 • STANDARDAND

CA'!;

• 6 - FT. § R- FT. 1;6DS

MARKET FORCES

L6N<::;THSH01-{LD FITINA c;ARA<::;6

• lASA R.6<::;1-{LATIONS ONLY • TR.t.{CK. lS-vtM?6R.S

(WITH 2-+SOMM "B-61:>)

• WIDTH vtND6'R. 2030MM

(

infrastructure • population density • 'larkmg • economy • taxation • insurance • ecology • culture • leg1sl

,c;., •

climate • consumer advocate groups • sales

) 500,000 ANNvtAL SAL6S

• security •

IIIIIIICILIUII

l

( '-- •

A "'R.6AL

TR.t.{CK."

• AMS'R.ICAN

"'g. t.{! L T

H-POIN

l SI

POSITIONING THE CONCEPT No vericle is ever designed in isolation, so it is important to look at other vehicles that it will compete against, or alongside which it will be sold. The market positioning graphic on the apposite page can provide a clear iilustration of how the new concept stacks up aga1nst other products. lt also shows where holes in the market exist. Each chart or graph ca n be set up with polarizing attributes on each side. The ex-

IND U

LOS

52

l

>i-POINT

STRI&&

ANGELES

ampie shows on-road versus off-road vehicles. The cars and SUVs are positioned from one extreme to another from top to bottom. From left to right is economy vs. prestige, so the vehicle ca n slide across the page accordlng to its cost. Other subjects can be pulled from the list offactors on p. 49 to make up severa! charts, ensuring that the concept does not clash with other products in the brand portfolio.

VEHICLE POSITIONING GRAPHIC This graphic helps to visualize where the concept falls withln the manufacturer's showroom. lt can al so be used to position the concept against the competition and highlight areas of opportunity.

OFF-ROAD

.......... White space shows an opportumty

PRESTIGE

ECONOMY

ON-ROAO H-POINT

l S3

INTRDDUCTION TO VEHICLE SEGMENTS At some point early 1n the design process, the concept will need to be classified as a particular category of vehicle, far instanoe a car or a light truck or a commerciai vehicle. This is because most countries have specific legislation far each vehicle category, which ca n affect design decisions. This legislation might range from specific design criteria and taxation policies to use limitations and emis· slons standards. Fora variety of reasons, most governments want to contro! the types of vehicles that use their nat1on's infrastructure. In addition, there are many other organizations that have vested lnterests In classlfying vehicles. Consumer groups need to test and compare cars and trucks and organize their data. lnsurance companies need to assess the risk for different types of products. Local authorities may apply operating limits on certain types of vehicles. The vehicle design ca n be affected by factors that range from crash requirements and overall dimensionai limitations, to the number of wheels and

ilghting specifications. Taxation classes are often determined by engine size and power output but may also be affected by overall size. value and the numbe· of wheels. Use regulations are usually set up to permit vehicles with specific functions to exce l in their duties. A good example is the off-road vehicle, which USA regulations allow to be designed without the same bumper regulations that appty to cars. This enables them to achleve good approach and departure angles in extreme off-road conditions. Neighborhood electric vehicles are allowed to drive on the main roads without ing 40mph crash regulations. This helps to reduce size, weight and cast, effectively reducing their fuel consumption and emiss1ons.

CAAS

MICRO CARS

S4

l I-I·POINT

ECONOMY CARS

LUXURY CAAS

SPECIALTY CARS

Each country. and often region. sets out classifications to either promote or inhibit certain types of transportation. In markets with high population density or limited natura! resources, the government usually tries to encourage the driving of smaller vehicles by taxing larger cars and the fuel that they run on. In some cases tax refunds are given for vehicles that are clean and ecologically friend ly. lf space is limited, then there might be incentives for driving vehicles under a certain size. The segmentatlon in this chapter is dlvided by archltecture. For example, economy cars come in many sizes but they ali share a common philosophy, so thelr architecture is usually quite similar. Luxury cars also come in a variety of sizes. For example, a midsize luxury car wiil usually have a different architecture than a midsize economy car. Therefore. the eight segments shown on the fo llowing pages are divided by clear architectural differences.

TRUCKS

MINIVANS

suvs

PICKUP TAUCKS

COMMERCIALVANS

H- POINT

l 55

MICRO CARS

This is the smallest type of enger car allowed to drive on ali roads. Mlcro cars are usually designed to meet specific dimensionai and performance targets which allow them to fit a certain type of vehicle classification. They are often designed for only two occupants and with a minimum amount of cargo space. A small (un· orthodox) powertrain package and small ti re envelopes al so help to minimize the vehicle's size and weight. The body 1s designed for llght-weight. iow-cost. and high-volume productìon but must stili meet ali local government impact regulatìons. They are usually configured with two conventionally hinged doors and a liftgate.

ECONOMY CARS

This group represents the largest share of the global enger car market and is often referred to as the B. C an d D segment of vehicles. The objective is to prov1de i'1expensive 5-enger-plus-cargo transportation, so the packaging needs to be very efficient. Designers look to achieve the largest interior space within the smallest eKterior box dimensions to minimtze cost, weight and aerodynamic drag. The powertrain and suspension systems are optimized for space efficiency, rather than performance. The body structures are designed to meet very high production volumes and low-cost targets. 56

l H·POINT

,

LUXURY CARS

Th1s segmen: is often referred to as the executive or E class. lnterior space, refinement, speed, handling and a prestigious appearance are h1gh prioritles. The powertrain, occupant package and tire envelopes are usually generous which result in large overall d1mensions. Tte body is des1gned for high-quality and often high-volume production, with attention to noise reduct ion t hrough optimized aerodynam1cs and structural stiffness. The suspension systems are uncompromlsed to ensure the handling and nde comfort are al so fully opt1m1zed.

SPORTS & SPECIALTY CARS

The main objectives for thìs segment are high performance and exotic design. Uncompromlsed powertra1ns, body structures, suspenslon,

oerodynamics and o low center of gravity are priorities. Tht:l occupèlnl t:m·

wonment is m1nimized and cargo space ls generally compromlsed Customers of extreme, high-performance sports-cars are usually affluent enthus1asts. so high purchase pnce 1s not usually an issue. This allows these cars to be built by hand in low volumes.

H-POINT

l 57

..

MINIVANS

This is a relatively young segment. defined by a enger-onented package, usually for seven or elght. They are designated as trucks in the US market due to their cargo-carrymg capability. Powertrains need to be large enough to pull the vehicles when fully loaded but packaged to have a mimmum impact on the occupant environment. The un1body construction 1s designed for very high production and closures usually include sliding rear doors. Suspension systems should be economica! and efficiently packaged wlth the rear suspension designed for load carrymg and nde-he1ght va n ance. Typ1cally, the interior wlll have a flat floor wlth the capabllity to recontigure and stow the seats. Additionally, the occupants will sit high for security and a commanding view of the road.

SPORT UTILITY VEHICLES - SUVs

SB

l · -POINT

The sport-utility segment has grown rapid ly in recent years, offering the fee ling of security, a strong image and to 4 to 8 engers. The majorlty of SUVs have longitudinal oowflexibllity. whlle beine; ertrains with 4WD and high ground clearance for off-road and bad weather driving. This is complemented by suspens1on systems with long travel, good articulation a1d aggressive tires. The body construction may be of "body-on-frame " type for large SUVs wh1ch are usually de·1ved from plckup trucks designed for serious off-road dut1es Some SUVs are designed for road and light trail use only, which is reflected in their enger-car-like systems and typically unibody construction .

TRUCKS

Pickup trucks are used for both commerciai and personal applications. Their durable construction, powerful, high-torque engines and 4WD are designed to carry and tow heavy loads in ali types of environments. Suspen· ston systems must be able to a wide range of loading conditions and offer various ride-height options. The body construction is traditionally body-on-frame and often is the basis for an SUV deriva:ive. Trucks come in numerous length configurations depending on cab and bed-size requirements.

COMMERCIAL VANS

Principally designed lo previde economica! cargo transportation for businesses, the architecture of these vehicles needs to be very flexlble to create a wide variety of derivative s. Usually, a uni body construction that ca n

be adapted to include a strong framework for open-bed versions and a platform for coach buiiders. The body design should also facilitate dimensiona! variants wtth closures that are sized for loading standard-sized otr jects. Powertrains and suspension systems are designed for heavy load carrying wlth mìn1mum intrusion into the cargo space. The footprint of the vehicle should be kept as small as possible to ìmprove maneuverability in urban environments. H-POINT

l S9

INTROOUCTION TO PACKAGE IDEATION The main objectìve for package ìdeatìon 1s to study as many system configurations as possible in a short period of time. The process 1s sim1lar to design ideation where each concept is sketched out loosely on paper and evaluated as a cluster of ideas. After senlng the runctlonal objectlves, there 1s a small wlndow of opportunlty in the product development process to be innovative with the vehicle arch1tecture. This w ndow often closes quickly due to project ti me constraints, so 1deas need to be free-flowing and clearly communicated. lt is easy to jump to conclusions and re ly on paradigms that have been applied on prev1ous projects and walk backwards into the future. So make good use of this prase of the proJeCt and don't hold back. once you're deeper 1nto a program there may not be an opportunlty to return to this phase. Don't worry if some of the ideas are bad; what appears to be a dumb idea during brainstorming can often lead to the development of a really good one later. Fìrst iook at the basic proportlons (as shown on the apposite page) and think about what may drive them. Next, configure some of the key elements-i.e., the occupants, cargo, t1res and po....ertraln-and look for opportunities. Look at the big chunks and see how they can be reconfigured to work more effectiveiy. The powertrain, for example, often provides great opportunity for innovation and will greatly affect the proportions. The occupant package and cargo storage 1s also an area where there is great potent1al for fresh thinking because they take up more space than the other elements. Although this phase requires a broad focus, dc not totally overlook small details. Often a minor innovation may be the key to a successful package

62

i t -POINT

Look closely at the functional objectives to seiect and piace each element. t-.ext look at the body structure. closures (doors. gates. hood & trunk) and breathing apertures to see how these may affect the overall proportions and design. Also look at the interior design possibilit1es. Seating and telematic concepts may have a great impact on the overall architecture. The example project on the following pages illustrate how you may go about this process. The word picture created for this example 1s "An Aspirational Commuter Ca r.· Th1s statement commun1cates both the phys1ca1 and emotiOnal aspects of the theme. lt sums up the vehicle and customer in just a few words, but also creates an open brief. From th1s heading, spec1fic objectives or targets for the conéept need to be developed. Look at the subjects on p. 49. Think about the three entities involved In the product development: the customer. the manufacturer and the market environment. Choose several of these to help steer the design. Some of these are simple, like top speed, fuel consumption, and the number of engers. Other factors like manufacturing strategies and internat1onal legislation will be more complex subjects. but should be given consideration. Try to think about how each objective may affect the basic architecture. Requirements for engers, ground clearance. a large engine, heavy cargo, and doors will have an impact lneven on a loose ideation sketch. Other less influential features like struments and trim may be ignored at this time unless there ls a spec1t1c focus on these systems. As a commutar vehicle it will probably be small, inexpensive to buy and drive, easy to park, carry only one, two or three people, and have llmrted cargo capacrty. lt may be sold ali over the world and therefore be manufactured in very high volumes. To be aspirational, the styling will be important and performance may need to be stepped up.

LOOSE EXTERIOR PROPORTION SKETCHES

OPEN WHEEL - LDW. LONG

Keep the sketches very simple; at this stage they are JUSt to look at basic proportrons. These three optìons look at vanous ways to approach the Asprrational Commuter Car.

1600 mm

The low car will probably be performance oriented to make it aspirational. The short vehicle wlll be more practical and easier to park and maneuver. The narrow concept will be able to cut throug11 traffic and be very easy to park. At this stage set some size limitations based on the known environmental requirements. For example. to park sideways, the length of the short car will need to be srmilar to the width of a large truck. To cut through traffic, the ultra-narrow concept will need to be the wrdth of a large motorcycle.

4000 mm

TWO BOX - TALL. SHORT

3500 mm

- - - - - - ----1.

ONE BOX - TALL. SHORT

3100mm

.__J

ULTRA-NARRDW

NARRO W

-'99Dmmj H·POIN

l 63

PACKAGE IIJEATION PROCESS Sketch severallayouts with the occupants, cargo. tires and powertrain. At this stage, don't mclude other elements in the package unless the design brief specifically requires a focus on other areas. Also. do not worrytoo much about scale. Accuracy is not important here. This will be addressed at the next phase of the process. The main objective is to get as many 1deas down on paper, quickly, so that you ca n think about how the exterìor proportions v.ìll be influenced by the major e le· ments. For example, when th.nking about the powertrain, just look at whether it ìs large or small, at the front or the back, longìtudìnal or transverse, electric or internai combustìon, FWD or RWD. Configure the package 1n as many different ways as possìble and exhaust ali of the possibiilties. Try to make sure ali of t he ideas meet the functìonal objectives and target spec•ficatlons. Each sketch should only take 5 to 10 mlnutes to draw. so ìt should be possible to create many ldeas 1n a short time perlod.

Lookìng at the example concept sketches, the bnef for thìs project didn't specify how many engers need to be carried, so the ideatìon work looks at layouts with one. two and three occupants. The study also tooks at the d1fferent types of engers. Knowing that a commuter car will need to be small and inexpensive the pov.ertrain opuons are limited an:! only very efficient package configurations are given cons1deration. Don't underestimate the magie that ::omes from drawing out your ideas. In the same way that a new design may develop as it 1s rendered, sketching out the architecture will often foster new concepts that would never have been conce1ved had they not been part of the ideatio'l process. This is a problem for many engi· neers who simply never sketch thelr ideas on paper.

TARGET SPECIFICATIONS Top Speed

75 mph

0-60mph

7 Seconds

Cast

99.000 - $12.000

Fuel Consumption

60mpg or Equiv.

Aange

40- 60 miles

Safety

5 Star Crash IIIHS Ei NCAPJ

64

l H·POINT

THREE ENGERS (l ADULT + 2 KIDS l

TWO ENGERS

(

·l)

High Seating Position

Large Wheels

(

Cargo

Seating far two

--Cl T?}-

cargo I.c.E. IBOOccl

8-yr. olds Electric

O

1a-

Fuel 110 gal.)

TWD ENGERS + CARGO TRAILER

Electric Motor

-----rne-

Cargo

l

Batteries/Controllers

THREE ENGERS

Cargo

-----c:J

High Seating Position - - - . Cargo Electric Motor

13SkWI Electric Motor-

(30kWI

L Batteries + Controllers

(12kWh

+ SkWhl

Batteries +Controllers

112kWhl - - - - cargo

H·POINT

l 65

As you work through this process. continue research ìnto the major elements of the package.

The cargo requirements should be set out in the functional ObJectJves. lf spectfic ìtems need to be carried. get the measurements and include these m the sketches.

Constder the seatìng pos1t1on for the occupants Think about the number of engers, how they wìll relate to each other. theìr orìentation and approximate locatton. Also. set up their height from the ground and pasture. Make notes on the drawing as you go.

lf the wheel stze or locations are tmportant. add information about dlameters. wheelbase. track. etc. Loosely sketch a body profile over each package to look at the proportìonal difference between each study.

The powertrain specification should be estimated from the target performance goals and approximate wetght of the car. Also look at whtch wheels wtll dnve.

TWO ENGERS (TANOEM l

ONE ENGER

Electric Motor 12Skw)

Cargo

High Seating Position

Electrlc Motor

--P L

Batteries+ Controllers IIOkwhl

SS ( 1-PO!NT

Flectric Motor - - - ' 130kwl

Batteries+ Controllers 112kwh l

ONE ENGER FWO

Batteries Electric Motor

TWD ENGERS

i

Crush space

Batteries

Cargo

. Batter1es Electric Motor

ONE ENGER RWO

TWD ENGERS ISTAGGEREDJ 1 Batteries + Cont rollers

l

Crush space

Elect ric Motor

Crush space

I.C. Engine ISOOccJ

Cargo I.C. Engine ISOOccJ Electrlc Motor

Fuel lS gal.l

H· POINT

l

67

COMPOSITE MICAO-BOOY CONCEPT Sketch the body structure. apertures and closures. look at various ways to open the doors and configure the body. Thmk about how the ma1n load bearing structural elements may be configured. Consider the materials and possible manufacturing methods that may affect the package.

l 'P. -......._ Lamps, wi.per 1-VAC ""'Sl:jstem A...d

eree.... for addi.tw...al ro..l. over protreetw""

t>oorttss bod!j st.de provU:Ces """ for A111. efti.cit...t çtl"ur.htvt ft>r <.i..d1 i.....paet "" tnn;.U,III.QL

qtr A...t:l si.U stn.<etw.re art Also part of the e.otttri.or

Tr:ILL si.LL for Crash 'Prottetw"" .§ Rlei.di.tl:l

sLU:Ci.""!3 t>oor (U:CeaL

for

(for &(yQw..A .§ 11\.QYYON spaees)

69

l

H-POINT

'RtAY

CiAtt

FWt>

Li."'-'

FIVE-PIECE ULTRALIGHT BODY CONCEPT This is a great tìme to look at unorthodox body structures and manufactunng processes. These will have a dramatic effect on the package and need to be thought through before laying out the other components. Notice 10 this example how the suspension and powertrain rnfluence or help the body desrgn. R6AR CRASH" STRI.-(CT\.(.R.6

CANDPY •c:il'l.\lt

Foa...._

b!1 wi.rt•

.........._

stun""0, l'ec:lals, .....i.rrol"S, ete. sUd

to see"-rt

t.{P1>6R "P>Dt>y

-LI! 11er eo""-postte s....speii\.SI-0"" eo...trol a .-....s a

spn.""0s

MAl N "&Ot>Y STR.t.{CTIA.R-6

sttc:l forwl!rc:l avw:t ptvotut for eas11 "sttp t""• o!Yiver t "--e rtSS/egrtsS

overstzec:l At.......t......_""- 6;ctr...sLoii\.S (Wtldtd FOIA.Y Pt.tet)

FRONT CRASH" STR.t.{CTIA.R-6

FOQlO<. §

sltol"t...to c:ll'ive postti.o"" to sLzt (to s«.Lt c:Mvel"s

LOW6R "&ot>y

M.._ttt.ll! 11er s...sl'eii\.Sw"" eo""trol ar....s Also t...el&A.c:lts I'I<.Dlc:lec:l t>RIV6

stY&A.et... re.

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fj l-t"-b i'\<.Otors tf(ieit ...t

wttj, 11\.l!rrow low-Yolu""0 reststl!II\.Ct ttres traii\.S .... for H-POIN-

l 69

INTRDDUCTIDN TO SIZING S PROPORTIDNS Setting up the sìze and proportion of a vehicle can be approached In several ways. The first approach may be purely emotional. You may have already decided that the concept will be large or small, high or low, have a short or a long hood. You will be working wìth a mindset that the vehicle needs to be designed to look a certain way for the customer to accept lt. lf this ls the case, the package can often be designed under the skin, because there wlll be nothing revolutionary about it. lt is taking what we already know today and simply refining it. This is a case of the package being lead by the design. Another approach may be driven by a specifìc requirement to meet dimensionai legislatìon or market segmentation. This combined with a challenging set offunctìonal objectives may require some innovative packaging to fit everything into a llmited envelope. The fina l methodology 1s to start only with the functional object1ves. This 1nvolves research into advanced technology to develop innovative solutions before build· ing the package around the occupants and new kinds of componentry. The exte· rior proportions ca n define the forms around this fresh architecture. lf some of the functional objectives for the vehicle are to flt into a small footprint and be fuel effic1ent, then a fully optim1zed pac.
MIO-FRONT ENGINE 72

l H-POINT

There may not be a great dea l of emphasis on larger cargo space, but room for suitcases and golf clubs might be an important requlrement. A smaller, two·box hatchback will be a more efficient and versatile design with a smaller angine, but larger cargo environment for carrying bulkier objects. So, proportlons are always going to rei ate to the function of the vehicle. This may be an obvious statement but every time a new project is kicked off, the design team should fully investigate what opportunity there 1s for the architecture of the vehicle to make an exciting statement about its intended function. Similarly, designers ca n consider how new technology could be applìed and how that might lead to a redistribution of the masses. New advanced propulsion systems, for example, are very different in their size, proportion and arrangement to conventional Internai combustion engines. So a concept that employs an electric powertrain should not look the same as one with a conventional internai combustion engine. The three sports cars shown below may have simìlar objectives but look totally different because their engines are in different locations. Performance cars vary a great deal in appearance for this reason. The left car has a large m id-front engine which creates a long hood. pushing the driver towards the rear of the wheelbase. The middle car is a mid-rear engine layout with the transaxle behind the angine. This package creates a longer rear end, pushing the rear wheel away from the driver. The right car has a rear-mounted engine which requires a lot ot mass behind the rear wheels but does allow a small amount of room for rear engers.

MID-REAA ENGINE

REAR ENGINE

PAOPORTIONS & BODY TYPES

SIZING THE CONCEPT

The side-v1ew proport1ons of the body are influenced by the occupants, cargo and powertrain packages. Additionally, the ground clearance. crash systems and aerodynamics will affect the profìle. Ali of these, in turn. are driven by the functional obj ectives. Below are some typical examples of various body types and proportlons.

After the initial ideation phase. the next step tS to determina the size of the vehlcle. The one consistent component l n each package is the scale of the occupants, so the scale of the concept ca n be set up around the driver and engers. Benchmarklng existing known vehicles wl li help perform this task. Notice the exterior shape has not changed but the vehicles are different sizes. Uslng the occupants as the basis for scaling, the size ca n be adjusted to fit comfortably around them.

ONE BOX

cee-

TWO BOX IFWO HATCHBACKJ

THREE BOX IRWD SEDANI

cc( l))_

LIMOUSINE

WAGON IRWDI

MINI CAR COUPE

MIO-ENGINE SUPERCAR

FAST BACK

ROAOSTER

MIDSIZE CAR

suv

PICKUP TRUCK

MINIVAN

COMMERCIAL VAN

MINIVAN H- POINT

l 73

VEHICLE CLASSIFICATIDN BY SIZE Often the size of a vehicle will put it into a category or market segment. Unfortunately, there is a lot of ambiguity in this area. This can be seen in the matrix on the apposite page, which may appear somewhat confusing. Slze is relative, so if you are working on a small car In Europe or Japan it wlll be much smaller than a small car In the USA. 1he type of veh1c1e w111 also make a difference. A small truck, far example. will be much longer than a small car, van or SUV. The market's view of size is constantly changing. Notice (on the apposite page) the size of the originai Mini & Flat 500 is much smaller than the current mode ls. Cars have grown considerably in recent years in both size and welght. In some markets, legislation will seta mixture of dimensionai, functional. weight or power-output dlvislon lines. These are usually there to help reduce vehicle size in regions with a dense population or for economica! and environmental reasons. Because some vehicles need to be configured a certain way to perform their intended functlon, they will be exempt from some limitations. Some divisions are mandated and strictly enforced, others are encouraged with tax incentives or penalties. Countries with poor economies, limited oil resources andjor high population densitles, wlll have stricter limitations.

74

l H-POINT

In the USA, personal vehicles have a gross vehicle weight (GVW) of less than 8,500 lbs. Commercìal (class A or B) trucks require special licenses to drive them. The mal n divislon far non-commerciai vehicles is between enger cars and llght trucks. enger cars have to meet stricter fuel consumptlon limits and their bumper design is govemed by low-speed impact requirements. To be classified as a truck, the vehicle has to oe either primarily designed to carry cargo, carry 9 or more people behind the driver, have an open bed or be designed for off-road use. Much of this criteria is open to interpretation, allowing some vehicles to be classified in elther category. So before starting the project, try to understand the objectives from the customer, brand and envlronmental perspective. Look at the size of competitive vehicles and the cars and trucks in the showroom of the brand. Check alllocalleglslation and think about how the environment and climate may affect the vehicle's architecture and classification.

fo.ro Focus l 4).55 w 1700

USA Class B Truck max w1dth 2590mm

2500

l

L 4530

WfGoll

BMW3S4idM

l 4190

l4525

w1a15

w1ns

,--- l

USA enger Car l Truck max width 2032mm

l

2000

!

l l t t

E E

l l l

l

i=Q 1500

Japanese " kel" cars max width 1480mm

fi

1957

l

Fiat SOO

t

t 2970

l

BMC\flnJ

l l l l

w 1320 L 3050 IV 1400

- 3550 N 1650

\

l

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Wl760

W1780

1\WITT

Mallla5

For
l 3520

L 3920

L 2525 w 1385

Ultra narrow l O OO recommended max width 1000mm

L 4-140

Cars SUVs

l

____,

4430

W1820 Porsche 9U

L 4460

J

W1810

2500

3000

Cars

cars 1 Wagons Luxury Cars Sports Cars

Small Famlly Car Small MPV Small Off Roader 4x4

Mi ero

A Class

B Class

c Class

IV 1900

w 1820

CtlfYSI<:t r&c l 5095 w 2000 Hol!d
bt!p OrnodCh!roi
TCMlUI

Jbcotna

l

5285 5615 w 1855

1--

-

( 85cu ft)

5000

5500

6000

Large Famlly Car E.xecutive Car (4.8m +) MPV Large Off Roader 4x4 C Class

o Ctass

SubCompact ( 85·100 eu ltl

Mini Compact

O Class

E Class

F Class

E Class

B Class o Class c Class Compact Midsrze ( 100110 eu ft) ( 100.120 eu ftl

Large i120 +eu ftJ

Small Wagon ( -130 eu ft)

Mtdsize Wagon LargeWagoo ( 130.160 eu ftl ( 160+ eu ft) Small Standard (450().8500 lb) ( under 4500 lbl

Small

Vans

Trucks

w 1990

DoQgo L 55.!5

4500

Super Mini

Wagons

SUVs

w

""•ll001807 • .1725

4000

3500

TrucKs

(MSN. Autos)

l

RR Pflaf11:.mt L 5835

.v 1950

(Trucks by GVWR)

Consumar Groups

CG) J

BMW 1 sene• l 5040

BM•V 5 "Series l tll;55 IV 1845

w 1690

Vans US EPA Classlflcatlon (Cars by interlor volume)

7òyO!f camry l 4605 Wl820

J

JJ(_((

VEHICLE LENGTH - mm J

2000

European Segments

l

.

CorfUI/;j

L 4530

w 1720

500

Cars Mtnivans SUVs

;560

1995

l'tJBlO

w 1650

CCTafl&O l 2565 IY990

MOfC-SCioss l 5160 1855

H>l!d
w lTSO

Mazlta Af•am l 4000

Euro NCAP

t--

Honoa CiVIC

L 3835

IY 1475

L 536015340 W2030

v.

T

P

o.ahatsu Ml»e L 3395

Fol!JflSO

l

l

a1JlJUlrL!J'

w 1680

w 1415

Smart For 2

a.,y SubUrbln

l "600

Wl650

Suzu•llll>gen R

l W2005

ì. r el ol( cc_J ' co _L_ Cl'lll\ CC

Wf Polo L 39!5

,_.,;,_;- J

4800

w 2060

AudJA4 l 4570

l 4180 W1840

EMWMinl l w 1690

l

L 4250

SconXB

OoiJgeRQill

CscMac Ucei;;Go t 5!45 W .lOOS

w 1730

Small SUVs

Midsize Larga Entry Luxury Cars Lullury Cars Ultra luxury Cars($100k+l Exonc Sports Cars ($ 70k..-) spons cars enger Vans 1 Cargo Vans luxuty SUVs Mtdsize SUVs LargeSUVs Small large & Heavy Pickups OvtyPdups

H-POINT

l 75

EXTERIDR LDNGITUOINAL PROPOATIONS Front lmpact Structure G Powertrain

Driver Package

Rear Occupant Package

Rear lmpact Structure & Cargo Space

The size and orlentation of the englne significantly affect the proportion of the front end. Free crush space for frontal impact is required around the powertrain and chassis components to help meet frontal impact requirements.

The space occupied by the dnver"s lower limbs ls determined by the chair height. An increase of chair height wlll shorten the horizontal length between the feet and the hips.

The distance between the tront and rear occupants (couple) wìll directly affect the vehicle length, which is why the rear engers suffer the most in smaller cars.

This space is mainly used to accommodate cargo, the spare t1re and fuel tanK. Protecting the rear occupants and fuel from rear impact will also influence th1s dirnension.

Overall length Targets Ei limitations The maximum overalllength may be a project goal established to ensure the vehicle fits into a particular market segment. Additionally, streetjgarage parking and maneuverability are aiso limiting factors. Accommodatlng a specific spindle locationjwheelbase and overhang may also affect the overall length (OAL). Excessive length wìll add cost and weìght and llmìt performance.

76

l H-POINT

FWO The front overhang and spindle is set up by the driveshaft location. - ---!_ __,,_________ _

+-- - - -- -

_ _______

RWO The front wheel 1s set forwa'd to improve approach angle and minimize the effects of a heavy load on the steering.

l •

•

l 4

The wheelbase is set up effic1ently around the enger location. Bed length is determined by function. They range from 850 to 2500mm.

The rear wheellocation is set close to the middle of the bed for ideai load distribut1on and ramp over.

.l

The three-box enger car with a front engine (on p. 76) 1s quite straightforward in its break up. Other vehlcles will have a similar set of requirAments governing the length of each chunk of the package, but may end up with different proportions because they have different functìons. Spindle locations are set by severa! different factors. Often the wheel center is slaved to a driveshaft locatìon, so the drìven wheelrs usually placed fìrst. The other spindle or axle may be located by the need for an efficient, short package or for optrmum weight distribution.

Rear cargo bay length is determined by functional requirements.

RWO l FWD The front wheel is set forward to allow the driver to be located In a forward location.

l

- --+--•-+...

l

The rear wheel locatron is set behrnd the srde load dcor whrch is designed to allow specific items to th'ough, which are usually over lOOOmm.

The engrne transmissron fuel tank and crush space are ali located behind the driver.

RWO The front wheel rs posltloned to establisl1 rt:dr wt ret:l is lint:cl up with perfect weight distributlon. ----!- - - -- -- - --+-- - -- - the driveshaft tocation.

H-POINT

l 77

EXTERIOR LATERAL PROPDRTIDNS

Shoulder Room Measured between the door trim s. this dimension is part of the equation to calculate intenor volume. The mam objectives are to mamtain a comfortable relationsh1p to the occupants and help reach interior volume targets.

1-----.--------l - - - - + - - - - - - - latera! Occupant location Often inftuenced by the overall w1dth llmitat1ons. the occu· pants may also be pushed outboard by the powertrain or interior functional requirements.

Ooor Construction The body-s1de profile, side {drop) glass and door construction. added to the shoulder-room dimension, will usually set up the widest point of the body.

Track S Tire Proflle Width A wide track will help to stabilize the vehlcle and reduce roll. The track and tlre width will often establlsh the overall vehiclo width for high performance cars where cornering. acceleration and braking are criticai.

79

l H-POINT

Overall Width The width is the most controlled of the three dimensions ano 1S usually governed by vanous authontles to ensure t hat each vehicle can function in its intended environment. Also, the wldth affects the frontal area of the car, which directly influences the aerodynamic drag.

EXTERIDR VERTICAL PROPDRTIONS

HEAOLINEA G AOOF SYSTEMS Space is requlred to accommodate trim ard varlous roo: systems such as sunroofs and roof racks.

EFFECTIVE HEAOAOOM The dlstance between the seat and the headliner is determlned by head clearance requirements and spatial expectations.

OVERALL HEIGHT The vehicle's handling, aerodynamics, ground-clearance needs and occupant comfort ali have to be considered when determining the overall he1ght. Garage and underground parking access can lim1t the max1mum height for veh1ctes such as SUVs and minlvans.

l

UNOEABOOY STAUCTURE

CHAIA HEIGHT

GROUNO CLEARANCE

Provides space for an appro::>riate structure. a separate Heavy-duty veh1clcs may frame system. Most unibody cars will require an integrated rail svstem under the driver's feet.

Lowering the chair height will help to lower the center of gravity and m1nim1ze the frontal area to reduce drag. Min1vans & SUVs utllize a h1gher seatmg posture to provide command· of-the-road seating positlons.

Off road vehicles require high ground and ·ramp over· clearances to avoid bottom1ng out on rough terrain. Sports cars will have m1nimal ground clearance to lower their center of gravlty and lmprove aerodynamic performance.

H-POINT l 79

KEY DIMENSIONS

WlOTH

These key dimensions are used to set up and communicate the size and attributes of the package. Developing concepts are under continuous scrutlny and these measurements help to keep the design team informed. Additional dimensions may need to be added depending on the type of vehicle and rts functional ob]ectives. An off-road truck, for example, may need to record ground clearance and bed length.

Length

The maximum width of the body (excluding mirrors) often measured at the B pillar.

Width Height Wheelbase Front Track Rear Track Front Overhang Rear Overhang Tire Size Tire 0 .0.

r.--- - - - - --+--

FRONT G REAR TAACK The distance between the tire profìle centers at the ground line.

TIRE SIZE G TIRE OUTSIOE OIAMETER 10.0.1 Tires are specifìed by thelr profìle wldth. height and the wheel diameter. These dimensions are also combìned to proouce the tire outside diameter.

HEIGHT From the curb ground to the highest polnt of the vehicle includìng the roof rack.

FRONT OVERHANG Measured from the front spindle to the most forward WHEELBASE surface ofthe body. - -------1--to--------+--The distance between the front & rear spindles.-t------.,_-

OVERALL LENGTH From bumper to bumper, (the sum of the wheelbase &

BO

l H-POINT

REAR OVERHANG Measured from the rear spindle to the most rearward surface of the body.

Front Headroom Front Shoulder Room Driver Lateral Location Forward Up Angle Forward Down Angle Couple Rear Headroom Rear Shoulder Room

SHDULDER RDDM EFFECTIVE HEADRDDM

Dlstance across the lnterlor tnm, 256mm above the H-

Measured from H-polnt t o the headllner a long an 8° llne (from vertical), plus 102mm.

FDRWARD VISIDN ANGLES Measured tangent to t'le eye ellipse. to t'le cowt or header trim.

OCCUPANTS LATEAAL LDCATIDN Horlzontal distance between the front & rear H-points.

From the centerline of vehicle to the centerline of the maniktn.

l 81

BENCHMARKING Benchmarking is the most empowering packaging tool a designer can use. lt provides the key buìlding blocks to set up the proportlons qutckly and with conftdence. After the functional objectives have been estaolished, start to research existing vehicles wrth simtlar attributes. lf the intended market segment ts mature. this should be a straightforward process. lf the concept is reaching into new and urr known areas. benchmarking will require more thought and creativity.

The overall dimensions, the occupant package. the powertrain package, crashworthtness. cargo storage and any other mnovative features incorporated into the desrgn can be valtdated by demonstrating their similanty to other vehtcles. Une up each comparison according to the story tt tells. For example, tf headroom is the focus, line up the occupant's heads to each companson vehtcle. 1t tt •s the H-point to ground dimension. li ne up the ground tines of the vehicles.

The illustrations on pages 84-85 show a sìmple benchmarkmg study, where severa! products have been selected for comparison and are supenmposed w1th the basic package of the new concept. Although this looks quite primitive, a great deal can be learncd from this simple study. Because an existing car or truck is the result of a huge amount of research and development. benchmarking serves to provtde a sound foundation to launch a new concept study, as long as the design team doesn'tJUSt follow the same paradigms.

lt is always advantageous to have access to a database of packages. Most companies will either buy these from organizations who specìalize tn vehicle measurement or they measure compet itive vehictes and maintain their own database of package drawings.

Berore starling Lhe study, it is a good tdea to examine a comparison vehicle and understand its destgn philosophy. Get to know the vehicle as intimately as possible by reading various consumer reports and test driving if posslble. After this, eleme'1tS of the package can be dissected and used where they make sense.

For basic benchmark studies, each package should contain the vehlcle outline, tire O.D. (outslde dlameter), spindles, occupants, h-points and heel location. These should be drawn in slde and front views. A full set of dimensions is also very helpful.

Break up each package according to the tnformation on pages 76-79. Givmg separate consideration to key elements that make up the overall dimensions.

There are many online resources which provlde valuahle information ThP. mtlrr ufacturers' websttes have ali thelr vehicle specifications and measurements. Websites like www.autos.msn.com have tons of information and can create dt· menstonal comparisons quickly. This information can be cross-referenced wtth vehicle-safety information from www.euroncap.com, www.safercar.gov or v.ww. safecarguide.com.

Ultimately. you will need severa! benchmark studtes to prove the new concept.

82

l

l-PDINT

Add the relevant dimenstons to each study to add a higher level of accuracy to the companson.

-· A GRAPHIC PACKAGE DATABASE The database should contai n packages which contai n the outlfnes, tires, and occupants drawn m side views and rear views.

cOX&niJcad?06ilco:2DJD!!Qc6T:020fJJ &+& bHrt cOd?òJ

co2.rJQJ tìrl R co3iJ R cQj BJ Q6d CCidihJ [Id c021{;) cO{E;) o

cQ?;Jd

a

G2d1?R co? hHd
o

fil h'J crf-P 61

o::.JrJ'eP

l=ciJ H-POINT

l 83

BENCHMARK STUDIES The example shown here is an off-road sports truck concept with a V12 engine. The fìve comparisons shown below demonstrate how elements of severa! different vehicles ca n be used to bulld and communicate the new concept. To set up the basic package for a concept. severa! comparisons are usually necessary. Each comparison will help the design team understand the various features and attributes of the architecture. The comparisons below show the fol lowing:

After developlng lhe concept to this level, start to conslder other large elements in the package, such as the fuel tank, spare tire, and stowing seats. Do not get too hung up on these components but respect the space they will occupy. As the project moves forward, an engineering team will become more involved and adjust the package accordingly. The mai n goal is to translate the emotion of the sketch into a rational model.

1. Ground clearance, wheelbase and driver heel height. 2. Driver posture, head environment and windshield location. 3. EnginejTransmission envelope. 4. Cargo storage. 5. Overall dlmensions.

V18 OFF-ROAO SPORTS TRUCK - IDEATION SKETCH

84

l

l. The concept has the same wheelbase and

2. The occupant has a similar posture and re-

3. The DB9 has a SlmilarV12 engine. This front

ground clearance as the Range Rover so it should have a similar off-road capability. The driver's heel is also a slmilar helght, provlding room for a strong and durable underbody structure suitable for off-road use.

lationship to the 911 interior environment Le.. the roof and winclshield. Note: The packages are lined up al the driver H-Point.

end comparison shows a simllar hood profile and front end to driver's foot relationship, proving the engine should fit. Note: The packages are lined up at the driver's bali of foot.

RANGE ROVER SPORT

PORSCHE 911

ASTON MARTIN 089

(Similar wheelbase & ground clearance)

(Similar head environment & driver posture)

(Similar engine size & location)

BASIC PACKAGE ORTHOGRAPHIC ORAWING This initial package may look primitive but lt is enough to start a scale model with confidence. Most of lhe main slab surfaces-i.e. , the side glass, body side, hood, roof and windshield-can be blocked in from these slde- and end·vlew proffles. The package will become more compiex as the model develops, but should be kept very simple a: the start.

4. The concept wl li have a slmilar bed size as the

S. Although the new concept is a different type of vehicle

Hummer HL Note: the packages are lined up at the occupant's shoulder.

than the Jeep, the overall dimensions are simìlar, helping to communicate the size. The occupants' latera! location (the transmission will between them} and the tracks are also simllar. Note: the packages are llned up at the ground and bumpers.

HUMMER Hl

JEEP GRANO CHEROKEE

(Similar bed size)

(Si11ilar overall length and width)

H-POINT

l BS

OCCUPANT MANIKIN INTAOOUCTION Il cannot be overemphasized how criticai the driver and enger packaging ìs to the overall architecture. The occupants or indirectly influence every aspect of the vehicle's design.

lt is often said that cars and trucks should be designed from the inside out. This refers more to the occupant package than the intenor systems.

The SAE has worked with various g'oups to establish anthropomorphic (s1ze, proportion and movement) data which represent the volumes occupied by drivers and engers as they sit and operate vehicles . The results of th1s data have been converted into sets of geo11etry that represents the stature of a 95th percent1le US male (97 .5% of the total US population. including females) s1tting in a car seat.

The ma1n objective is to set up the driver and engers to be comfortable and safe, then create an envelope around them a1d use key reference data within their geometries to set up the rest of the veh1cle package.

This geometry can be used to set up the lnterior systems. locate controls. complete v1sion studies, position the po·Nertrain, establish the wheeljtire package and even piace the bumper beams.

The most lmportant reference point In the package is the driver's hip (Hl point. This is also referred to as the Seating Reference Point (SgRP). Almost every el e· rnent of the package will be 1nfluenced by its location and if modified, the effects rnay be seen throughout the vehicle.

The limbs, torso and head of the populatlon sample are measured individually to create a manikin that is built from 95th percentìle male parts. The sittmg manikìn can be utilized in two halves, from the H-point to the feet (to establish leg room} and from the H-potnt to the head (to set up the head environment}.

Each car company wlll use severa! rnanikins that suit their purpose. One of the most popular occupant packaglng t ools is the SAE 95th percentile male rnanlkin, which ls ideai for setting up the initìal interior space, ensuring that the vast majority of the global population wlll fit into the pacKage envelope.

After the initial package has been built, other smaller manikins (5th percentile fernale and 50th male) are used to ensure that smaller people will be able to drive In comfort and safety.

95th percentile male !USI standing height

5%

SO% Population Sample

BB ( H POINT

95%

Upper Body

H-Point or SgRP - - - - IHip Point or Seating Reference Pointl The most important reference datum in the package.

H- POINT

l 89

THE ANATOMY OF THE SAE IJ886) 95th PERCENTILE MALE DRIVER MANIKIN H-POINT ( HIP POINT) or SgRP (SEATING REFERENCE POINT)

95th PERCENTILE HEAD CONTOURS ( SAE 1052)

The ma1n reference pomt tor the occupants and one of the maJor datum po1nts far the vehicle package. Often referred to as the ··seating Reference Pomt" (SgRP or R-point in Europe). it is always located on the comfort (accommodation) curve.

The head contours are defined by three-dimenstonal surfaces and represent the areas withln which the 95th percentile occupant heads are contained. They Incorporate seat·track travel and head movement. The position of the head contour is determ1ned by the H-point and back a1g1e.

ACCOMMODATION CURVE ( SAE J151 6-1517)

This curve maintams the correct relationship between the H po1nt and foot to ensure a comfortable posture tor the driver's legs while operating the foot pedals. ACCELERATOR HEEL POINT

The heel-point location is often referenced to define the ftoor and step-in height.

VISION ANGLES

The upper and lower vision angle hnes are constructed tangentially to the 95th percentile eye ellipse and touch the first elements in front of the driver wh,ch obscure upward and downward visior. These are instrumental in the set up of the wmdshield aperture.

BALL OF FOOT POINT

EFFECTIVE HEADROOM POINT (SAE J1.100)

Located on the accelerator piane. A main reference point tor frontal 1mpact crush space measurement.

The 1ntersection of the headliner tnm and a hne s• from vertical, through the H-point. These are used to set up hard points on the roof surface above the headliner t rim or sunroof.

ACCELERATOR FOOT PLANE

This piane rotates about the ankle plvot and is usually locked at 87° to the shin centerline. TORSO LINE

Define::. lhe llock ongle inclination. 95t h EYE EUIPSE ( J941)

The 95th eye ellipsoid represents a three-dimensional volume within which 95 percent ot driver's eyes will be contamed. lts ocation remains constant to the head contour.

90

l H-POttH

LOWER LIMBS

The leg geometry consists of the shm and thigh centerlines . which are constrained by the ankle p1vot and the H-po1nt. Their confìguration is automatically updated as the H-point to heel relationship is changed. The th1gh centerhne 1s used to set up the steering wheel location and the shin determines the knee-blockcr surlacc on the instrument .

s· line effective headroom point

occupant centerline (lateral location l 95th percentile head contour

95th percentile head contour

95th percentile eye ellipse dOVIIOward vision angle

thigh centerline

torso line lback anglel

shin centerline H-point ISgRPJ

bali of foot piane

95th percentile accommodation curve ankle pivot bali of foot point

H-Point ISgRPI

accelerator heel piane accelerator heel point

The helght variation llmited by the accommodation curve only applies to enger cars and light trucks. Other vehicles such as golf carts, NEVs, and delivery trucks, which are designed for easy ingressjegress and short-distance driving, may require a taller seating posture. In tt1ese cases the H-poìnt-to-heel vertical dlmensìon may be as high as 530mm. This also often appties to Class 8 vehicles (heavy trucks) whìch usually have 150m m of vertical seFtt travP.I to ar.r.ommotiFtte shorter drivers. Seat adjustment in enger cars ls mostly horizontal.

H-POINT

l 91

SETIING UP THE DRIVER HEIGHT S PDSTURE For crossover veh1cles, think about combining the attributes. For example a sporty off-road veh1cle may have a high heel point for ground clearance and structure. but may need a low chair height to keep the roof height as low as possible. lf the engine ls in the rear. forward visibility over the hood won' t be a problem.

The driver's height and pasture are govemed by several factors. namely: center of grav1ty, aerodynam1cs. mgressjegress, comfort and visibility. The vehicle height should be established by a combinati an of these factors. The graphic on the following page shows how the dnver height and posture vanes w1th the functionality of each vehicle type. The dimensions provide an approximate range to help set up the dnver 10 a trad1t1ona1 package.

SETIING UP THE REAR DCCUPANTS The "couple" dlmens1on 1s used extensively in - the initial package process to gauge the amount of leg and knee room the rear occupant has. This is a horizontal measure between the H points. Later m the process. when the package is more mature, spec1fic measurements for knee and leg room are recorded.

r

Couple

The head form envelope does not Include seat track travel the seats sl1 de fore and aft.

' l

"Theater· seallng elevates the rear occupant to improve visibilìty over the driver.

•

Because the rear occupants do not contrai the vehicle, their leg pasture ls not controlled by the accommodation curve. Notice how the knee angle is quite dlfferent to thc driver end thcir fcct ore flot on thc floor. Sccond, thc dcmogrophics for the rear occupants may be different to the front occupants. They may be children or people who are shorter in stature to the driver, so headroom, for example. may be less.

92

l

i-POINT

Note the pasture of the lower limbs are quite different to the dnver. These are not constrained by the SAE accorrmodat1on curve. Lastly, the function of the rear compartment will often be qu1te different to the front, so space may be needed for recllnlng engers, swiveling or stowing scots, video monitor etc. These will ali affect the spaclal reqUirements and H point location. Other factors to consider are: roof height fuel tank s1ze. rear cargo, three across seating, rear suspension and rear tfre requirements.

VARIOUS DRIVER HEIGHTS FROM GROUND ANO PDSTURES

H Polnt to Ground CIJolr He1gh1 Effective Headroom BackAngle

300 350 .. 135-180 950 960

Jo•

400 200 970 ?2°

500 250 1000 25•

700 800 300 350 1010 1020 22" -24°

700 - 750 300 350 990 1010 22°-24°

700 - 950 300 350 10:/U

22°·24 j

't

' H-Polnr 10 GruurJIJ

SPORTS CARS

ENGER CARS

MINIVANS

SUVs

LARGE OFF-ROAO TRUCKS

The dnver height is kept as low as possible to lower the center of gravity and reduce drag. Get· tlns in and out of the car may be difficult but that 1s a compromise sports car owners will accept.

Most enger car H-polnts are set up for a combinat1on of easy ingress;egress and low center of grav1ty. Although not as extreme as most sports cars. they are retat1vely low.

Usually set up qulte high to provide a sense of security and good visib1lity. The tali chair height also helps to create an efficient package and prov1des excellent 1ngress and egress.

A combination of high ground clearance and a durable un derbody structure push the heel height up. The chair height is a Iso tali to help the dnver see over the engine. which is usually mounted high above the front axle.

Slmilar to SUVs, the occupants often sit very high because of the ground clearance and the separate frame that the body sits on. Because the engines are usually very large and mounted h1gh, the dnvers eye point may end up in a very high position .

.. Ali measurements in mlllimeters unless otherwise noted.

H-POIN

l 93

OCCUPANT ENVIRONMENT DIMENSIONS Below is an illustration ofthe major dimensions that set up the interi or environment around the occupant package. These are part of the SAE J1100 measurement index. Using the same measurement system for every project ensures that there is no confusion and the package database remains consistent.

W27- l

.,

W27-2

W3-2

H25-l

Far steering wheel set up. see p. 102.

94

l H-POINT

H25-2

APPRDXIMATE REFERENCE DIMENSIDNS The table below cont ains some examples of dimensions taken from current production cars. Use these to set up an inìttal package, assuming that the crit eria that has driven t hese numbers ls slmilar to your concept. As t he design develops and key elements In the package evolve, these may change.

As you work through t he process, develop an understanding of the factors that govern these interior environment dimenstons.

DRIVER G FRONT ENGER

c: u

Heel to

Chalr

H polnt

Back

Effectlvo

Upward

DownW'd

Shou/der

Ground

He/ght

toground

Angl e

Head

Vlslon

Vlslon

Room

Room

Angle

Ant11e

HlpRoom

Latera/

Couple

Locatlon

ws

(Ref)

H30

HS

A40

H61

A60

A6l

W3

NEV

325

400

725

15.0

1075

11.0

10.0

.

SPORTS CAR

175

150

325

28.0

950

8.0

5.0

1350 1275 325/400

MICRO CAR

350

275

625

21.0

1000

14.0

11.0

1200 1150

300

SMALL ELECTRIC CAR

450

250

700

24.0

975

15.0

9.0

1325 1325

SMALL CAR

225

250

475

24.0

975

15.0

7.0

MEDIUMCAR

250

250

500

24.0

975

14.0

MEDIUM COUPE

250

175

425

24.0

950

LARGE CAR

275

250

525

24.0

Ul

<(

REAR OCCUPANTS Chalr

Back

Heltht

Angle

Effectlve Head Room

W20

LSO

H30-2

A40-2

H61-2

275

.

.

.

.

-

-

.

-

350

750

275

26.0

950

1350 1325

350

750

275

27.0

7.0

1475 1400

l 350

850

275

13.0

5.0

1375 1325

350

750

200

975

14.0

ò.O

1500 1450

375

900

975

15.0

7.0

1550 1500

400

975

l

l

Shoulder

Hlp

Room

Room

W3-2

WS-2 1W20-2

Latetal

Locatlon

-

-

.

.

.

.

.

.

1325

1325

325

950

1350

1325

325

27.0

950

H75

1400

325

27.0

875

1375

1325

325

275

27.0

975

1500

1450

400

300

28.0

975

1550

1450

375

.

LARGE LUXURY CAR

275

275

550

22.0

MINIVAN

425

350

775

20.0

1010

19.0

11.0

1575 1525

425

850

375

22.0

1000

1575

1525

400

SMALL SUV

400

350

750

22.0

1010

15.0

3.0

1425 1400

400

800

375

24.0

1000

1425

1375

375

MEDIUMSUV

450

300

750

22.0

1010

14.0

5.0

1500 1450

400

825

325

24.0

1000

1500

1450

425

LARGESUV

450

325

775

22.0

1025

14.0

7.0

1650 1600

375

875

350

24.0

1025

1650

1600

375

SMAU TRUCK

400

300

700

22.0

1010

14.0

7.0

1475 1450

375

625

325

18.0

950

1475

1425

400

LARGE 4x4 TRUCK

600

350

950

22.0

1025

15.0

9.0

1700 1650

475

950

375

18.0

1025

1700

1650

475

COMMERCIAL VAN

725

350

l 1075

22.0

l 1010

10.0

10.0

1675 1625

525

900

425

19.0

1000

1675

1625

500

l

H·POINT

l 95

The interior components can be divided into about seven systems, shown on the apposite page. These are typically developed and manufactured by various suppliers who work with Lhe major auto compan1es from the beginning ofthe design process. They will often be delivered to the assembly line complete and ready to install. The interior design on most projects will follow the exterior. There are exceptions. particularly if the vehicle interior has special features which will affect the overall package, such as rotating or stowing seat systems or special cargo needs. These will drive the initial package together with the occupants, creating hard points to work around.

98

l H-POINT

An lmportant concept to understand is that the interìor must be safe, so each component is designed to reduce lnjury to the occupants during a collision. Some parts contai n the active and ive safety systems, such as the air bags, seat belts and knee blockers. They can be attached directly to the vehicle structure to aid their function. Other ltems, such as the headrests a"'d roof linings are design ed to prevent head and neck injuries as well as trauma, 1n the event of severe impacts.

....

Trim

Controls. lnstruments G Switches

The steering wheel. shifter. hand brake and turn-signal The trim features exten stalks ali have to be located where the driver can sively in early package use them effectively and also allow easy ingressi studies because it is deegress. Some of these pnmary controls may be set signed to reduce head trauuo with the initial package if they influence other ma if the occupants strike key systems. 1he lnstrument cluster is usually the upper body structure durseen through the steering wheel, so accurate ing an impact or rollover. As vision studies are crucial. The illuminated the roof rail, pillar and header screen should also be shrouded from reflectsections are developed, they al· ing in the windshield by the cluster brow. ways rnclude the trrm. The door Other switches and controls wifl need to tnms are set up relative to the be located within reach of the driver and cccupant's H-point to establish the front enger. armrest height. the locatron of door release levers and various swrtches for power windows and locks.

The tnstrument II.P.l G Consoles Generally. the I.P. will not rnfluence the exterior proportrens of the car, so rts desrgn ca n follow the exterìor. However, many of the key components are directly related to the driver location and posture to previde reach, visibility and safetv. lf the occupant package changes, it wlll tear up the I.P. and console design. This is one reoson why the interior design is not started until the exterior development is qurte advanced. Overhead consoles will help redistribute some components and free up "real estate" on the I.P. bu: their size is often limited by the sunroof.

Telematics The telematics may have a dramatic effect on the layout of the vehrcle package. For some cars it may just be a navigation screen and an mp3 dock. but others may have a 50" flat screen TV with a full home theater system. This was not possrble a tew years ago, so new technology may redefine what a vehrcle represents to the mass market.

Seats G Seat Belts The seats are desìgned around the occupants' package locallon and posture. They occupy a large volume and adJustment ranges have to be factored lnto the location of adjacent components. Specral seat systems that rotate or stow wlll require studles at the inltral stage. The front seat belts will normally be 'attached to the 8 pillar. In some vehicles there is no 8 pillar and the belts are attached directly to the lower body structure and/ or the seat structure. Attachi'lg belt anchors to seats adds consrderable stress loads to the seat structure.

Carpet The carpet does not rnfluence the package too much other than raislng the heel points. Luxury cars may have a lot of sound insulatlon which can stack up to become slgnificant to the packaging of the heel point.

Heating, ventilatron and air conditionrng systems are clearly vislble in ali cars because of the air distribution vent and controls. What are hidden are the modules that heat and cool the air and pump it through the cab· in. These units can be Quite large and are usually lo· cated between the foot wells, behind the center stack.

H-PDIN

l

99

N The instrument panei {I.P.) is one of the most complex assemblies in the car. On most conventional interiors the area around the instrument cluster ls very crowded, Wilh the steering column, instruments, I.P. structure and HVAC ducting ali competing for the volume. The center stack layout also needs to be carefuily prioritized and organized so that vent outlets. HVAC controls, telematics (naVi· gation, radio, CD, etc.), cup holders, switches and storage trays ali fit and are ergonomically positioned.

Additional consideration must be given to safety because much of the ins-Ju· ment is within the head lmpact zone. This means that the contours, radii and hardness of ali surfaces have to be designed to ali mterior safety leglslation and testing procedures. Also, during a high-speed fronta l impact the occupants rely on the knee blockers and air bags to restrict their forward travel and cushion the impact. For this reason the relationship of the i.P. and controls to the driver and front engers is criticai, with everything set up for reach, vision and safety. Special consideration should be given to vehicles in global markets where both left- and right-hand drive configurations are required.

100

l

h-POINT

l

AIA DISTAIBUTION VENTS

STEEAING WHEEL

TELEMATICS SCAEEN

Mounted on the steering column which is usually adjustable and attaches to the main LP. structure.

Primarily for navigation, providing TV & video in the I.P. is lllegal in most countries.

Positioned to blow conditioned air at the occupant's tace and torso.

INSTRUMENT CLUSTER Usually housed behind the steerìng wheel, occaslonally in the center stack, the instruments usually include the speedometer, tachometer, fuel gauge. engine temperature, battery charge. and waming

OOORTRIMS The door trims are usually designed to flow into the l. P.. so these are often modeled and sketched at the same tfme. These also relate closely to the occupants and set up the "shoulder room· ano "hip room ·· dimens1ons. The armrests, release levers and switches should be set up appropriately to the occupant. The door trims are also designed to help minimize lnjury during a side impact.

lights.

ORIVEA'S SIDE AIA BAG Packaged In the center of the steering wheel it works more effectively if the steering wheel is angled toward the driver's face.

ENGER SIOE AIA BAG

000

Can be mounted in the top pad or on the front of the instrument .

KNEE BLOCKER IGLOVE-BOX ODORI KNEE BLOCKEA

CENTER STACK 6 CENTER CONSOLE

Working in conjunction with the airbag, it ls a component of the active safety restraint system (SRS). lts relative location to the occupant ls criticai lo prevent an unbelted occupant from "submarining·· durlng a frontal impact. lt is connected directly to the mai n LP. structure to provide a sol id pad.

The shifter, tele11atics, HVAC controls, vents, radio, cup holders and banks of switchas may be housed in the center stack and should be within easy reach of the driver and enger. The SAE J287 recommended reach zones should be utilized to piace these items.

Working in a s milar fashion to the driver's knee blocker, il utìlizes the giove-box door to provide a solid pad to prevent forward travel off the seat.

H-POINT

l 101

CLUSTER VISIBILITY The instrument cluster visibility is set up through the steering wheel using the 95th percentile left and right eye elllpses which project binocular vision lines onto the cluster piane resulting In a ·moustache"-shaped area. The instruments should be designed below these lines.

\ CLUSTER GRAPHJCS PLANE ____________.\

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300-325mm

KNEE BLOCKER The location set up by a complex process involving the 95th, 50th and 5th (female) percenlile manikins. The knee blocker surface usually ends up about 120-150mm from the shin centerllne.

SHIFTER Can be mounted on :he steering column, I.P. or floor console. The shìfter shown above is located on the vehicle centerline and is roughly in line with the manikin's knee. The throw will vary but will be approximately 150mn for automatlc transmisslons. 102

l H-POINT

The steering wheel center 1s mounted on or close (within about 10mm) to the driver centerline and usually has a diameter of about 38o-400mm. In s1de view it is set up to the occupant relative to the thigh and H-point. The angte of the steering wheel is roughly 90° to the column which is itsetf normally between 20"· 24" from the horizontal.

The bottom of the steering wheel to the thìgh centerllne is usually between 80lOOmm. The distance between the base of the steering wheel to the H-point 1s usually between 300-325mm honzontally.

' Cluster binocular vislbillty "moustache" projected onto the cluster graph1cs piane. The instruments should be located underneath this.

\

. ...--\

Dnver centerllne - the . steenng wheel centerline should be w1th1n 10mm of the driver centerllne.

H-POINT

l 103

The ob;ective of the reach envelopes IS t o previde recommended zones to locate each contro! lever or knob that the driver may need to adjust while drivmg with a seat belt fastened. The geometry for these envelopes 1s g1ven in SAE J287. The

SAE J287 reach envelope sect1ons - - created between 400mm outboard of the driver and 600mm inboard.

104

l H-POINT

envelopes are represented by a series of sect1ons cut every hundred millimeters, from 400mm outboard of the driver centerline to 600mm inboard. These sec· tions relate to the H-point location In x, y and z directions.

A .L N l Most car seats are made from cloth or foam. ed by a sprung steel frame mounted to adjustable tracks which sit either on the ftoor or on risers as shown opposite. Establishing a relationship between the H-point and the seat ìs ìmportant but dlffìcult to contro!. l he seat cush•on toam and cccupant Hesh combtned w111 compress about 50mm, so the seat should be drawn intruding into the occupant. After the seat has been manufactured, the 3D H-point machine (SAE J826, 76kg) can be placed to check the accuracy of the final H-point location. The headrest is designed to prevent whiplash irjuries during a rear impact and is reqwed to be at least 730mm above the H-point and 31.5mm behind, with the torso back angle set to a nominai 22°.

106

l H-POINT

SE A PA .K GIN[ì Seats take up a large portion of the interior volume, especially when their full range of adjustment is taken into consideratlon. Always ensure that adequate clearance (15mm) is designed between the movable seat components and the adjacent systems-i.e., door tnms and center console. Note: On vehicles with very low cha1r he1ghts, the seat tracks may be mounted vertically on the sill and console to help make the seat he1ght compact.

-· AR A

T

The act1ve restraint systems are desìgned to protect the front occupants in a high-speed frontal impact. even if they are not wearing seat belts. Notice that the momentum of the driver causes the manikin to slide forward until the knees hit the knee blocker on the ìnstrument . The a1r bag deploys 10 a split second to cushion the impact and protect the driver from hìtting the steerìng wheel. The

enger side air bag deploys from either the top or rear of the ìnstrument in a s1milar fashion. Side curtain and seat bolster air bags also deploy from the sìde ra11 and seat cush1ons to protect the dnver's head and torso in side impacts.

knee blocker

H· POit-.1 1105

, ...

H-POINT TRAVEL RANGE Seat adJUStment will vary depending on the size and cost of the vehicle. Luxury cars will have the most travel with fore and aft travel or 250mm along a 5° incline. About 40-80mm of this is rearward of the H-point, and 55mm of vertical travel up from the H-polnt ls typical.

---

315mm

1 ,-f_

Headrest designed to prevent wh1plash during a rear impact.

'h

.,.

730mm Minimum

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Pivot and recllne mechanism Seat Riser Seat Track

Sill Trim Seat Frame Seat Tracks

H-POINT

l 107

AL H

DI

R AR EA

ldeally, the seat should be designed to previde comfortable seating in the uprlght position and also to stow efficiently in the foot well (with the headrest in piace) to prov de a flat load floor. Achieving this wili depend on the under-floor packaging of t1e suspension, fina l drive system, fue l tank. exhaust, spare t1re and body structure. An lnclined rear floor will help to create a flat load floor with the seat in a higher position.

An inclined load floo· helps to provide more space for under-body

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The rear floor design is driven by lhe packaging of the suspension, fina l drive system, fuel tank, exhaust, spare tire and body structure.

108

l H-POINT

YPICAl MINIVAN 5 TOWING SlAP1 Minivan floors are usually flat and qu1te high so stowing seats flat into the floor IS poss1ble with some creat1ve under-floor packaging. Because the chair height 1s otten high, the seat risers can be used to articulate the seats into their stowed position. When the seats are In their norma!. upright posìtion the vacant underfloor storage is an add1t1onal bonus for hid1ng valuables. A feature of this magnitude will have to be considered at the inltlal package ldeatJon stage

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H· POINT j 109

The customer's llfestyle will dictate the type of cargo he or she will carry. Here are some examples and approximate dimensions.

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ICE CHEST l COOLER

1420mm

These are sold in various sizes, the larger ones are between 50-100 liters. 50 liter 700mm x 380mm x 440mm 100 liter = 930mm x 400mm x 440mm

1770mm

AOULT MOUNTAIN BIKES

=

Most bikes have qulck-release wheels and saddles which makes them eas1er to store in a vehicle. The wheel diameters are usually 660mm.

PLYWOOO SHEETS Building materials are sold in standard sizes. Large plywood sheets are 1220mm x 2440mm (4 ft. x 8ft.).

1250mm

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GOLF BAG These vary quite a bit In plan·view size but are usually about 1250mm high, with the clubs.

110

l H-POINT

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LUGGAGE 760mm

150mm

Suitcases come in ali shapes and sizes. A typical large suitcase's dimensions are illustrated at left.

NIN Cargo can take up as much space, or more, than the occupants, so it is worth thinking about from the start. Severa l factors should be investigated to determine the architecture adjacent to the cargo storage area. 1) Overall dimensions are usually designed around spec1fic items to be carried . Thls often relates to the customer's lifestyle.

t

2) lnterior volume is a big selling point in enger cars (see p. 113). lf several smaller items are carried, the volume measurement helps to determina how one car compares to another. 3) Aperture size should be as big as possible to allow large items to be fed into the cargo bay. 4) Lift-over height and floor height should be as low as possible. For most vehicles this will be just above the bumper height (530mm). For trucks the load floor may be quite high to allow for the frame rails and suspension travel.

Llft 'over

PICKUPS ANO COMMERCIAL VEHICLES These types of vehicles are designed around their capacity to carry cargo. The bed length or cargo bay varies between 1700mm to 2450mm for most commerciai trucks. Personal trucks may have beds as short as 850mm.

5) Suspension design may need to be compact to help lower the load floor, or very strong to carry heavy loads. 6) Load floors should be flat to make organizmg and moving heavy objects easier.

7) Underbody and seat design should be set up for maximum space flexibility. 8) Tumblehome

& backlight attitude should be as vertical as possible.

9) Rear wheel placement should be set up for opti mal weight distribution.

HATCHBACKS G WAGDNS Designed for multifunction between carrying cargo or rear engers. Exterior body shapes may compromise cargo-size potential. The seats will usually fold down over the fuel tank.

PLYWOOD /

4" x 8' plywood sheets stacked between the wheel house trim.

Aperture height

TIAE IN JOUNCE The rear track and suspension geometry is designed around the cargo width and load-floor height.

MINIVANS The angled floor provides a low step In height far the driver and a lift over at lhe rear bumper helght. Loads are easler to move around lf the floor is flat. The underbody components are designed around stowing the seats.

H-POINT 1111

The interior volume index is used primarilyto determine how much usable space is available for the occupants and cargo. The volume is reported in cubie feet or cubie meters and is the sum of the key interior measurement. shown right. Target volumes are often set out in the funct1ona1 objectives. Creating a competi· tive space becomes an important marketing tool, so these numbers are often

112

used by consumer groups to describe how efficient a package is and how it stacks up against a competitive vehicle. In the US, the Environmental Protection Agency (EPA) uses the interior volume to determine vehicle-slze classifications.

Class

Mini Compact Car

Subcompact Car

Compact Car

Midsize Car

Large Car

Small Wagon

Midsize Wagon

Large Wagon

Cub.c Feet

under 85

85.99.9

100 ·109.9

110-119.9

over 120

under 130

130. 160

over 160

l H-POINT

-· EPA INTERIOR VOLUME INOEX Front lnterior volume + Rear lnterior Volume + Cargo Volume FRONT S REAR IENGERIINTERIDR VOLUMES Head room x Leg room x Shoulder room (Use hip room if it's larger than shouider room)

CARGO VOLUMES Rear Seat Height x Average Trunk length x Rear Shoulder room

Front effective headroom

r

Rear effective headroom

A'""age ca•go leogth

l

Front /rear hip room 150mm-- - Note: The effective headroom dimension is measured between the H point and the headliner trlm, then 102mm is added. This addit1on measurement represents lhe distance from the H poinl to Lhe compres:setl :>eat t:u:>flìon.

Hip room zone - lOOmm high x 150mm long box measured rrom the H-polnt as shown.

l -

mm 25 mm

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Hip room zone, side view

H·POI'H 1113

POWERTRAIN ANATOMY THE BASIC ANATOMY OF THE INTERNAL COMBUSTION ENGINE (I.C.E.) POWERTRAIN The simplified graphic below shows a side view of a conventional, longitudinal. front-engme, rear-wheel-drive layout. Other mternal combust1on engme conngurat1ons can look completely d1fferent but conta1n the same basic elements.

THE ENGINE These come in many different s1zes and configurations but they are made up from Slmilar components: the cylìnder block, cylmder head, oil pan (sump), pistons, crankshaft, flywheel, induction system, exhaust manifold. starter motor, accessory drives and severa! other auxillary components. Due to 1ts size. weight and relatiOnship to the wheels 1t ls one of the most lnfluential components in the package.

FUEL TANK The volume will depend on the size and range of the veh1cle. The ma in factor to consider for fuel-tank packaging is its proteçtion during a high-speed impact.

TRANSMISSION Manual or automatic transm1ss1ons are usually attached to the end of the engme to feed the power at vanous speeds to the fina! dnve. The clutch (manual) or torque converter (automatic) is sandwiched between the engine and transmission.

COOLING The coo11ng module is usually packaged at the front of the vehicle where fast-mov1ng cool air ls easy to access. Cool1ng modules are sized according to the engine power and loading capacity. Often other coolers for oil. air conditlonlng, transmissìons and intercoolers are packaged together wlth the engine cooler, creating quite a large volume that needs to be placed where there ls a1rflow.

116

EXHAUST

FINAL DRIVE

Exhaust packaging is not usually the focus of early package studies. but large components in the system such as catalytic converters and silencers should be given some thought.

Th1s comprises the drive c;hafts, differentials and transfer case (for 4WD). Their motion, linked to suspens1on travel. should be consldered dunng the 101llal package study.

l H·POINT

..

THE BASIC ANATOMY OF AN ELECTRIC PDWERTRAIN Packaging an electric system requires a different attitude to a conventional powertrain. Here the motors are relatively small but the energy or fuel-storage systems are quite large In comparison to those of internai combustion systems. The mal n thing to take advantage of is the low-profile potential for these components. lf the system can be packaged under the floor. for instance, it allows the des1gner the opportunity to reduce the overall length of the vehlcle and change the exterior proportions.

BATTERIES l FUEL CELL

THE MDTOR S FINAL DRIVE

The electric power can be stored in batteries or created by a fuel celi . The batteries can be made from various materials based on cost versus power density requlrements. The system consists of severa! components includlng the fuel stack. compressor and hydrogen fuel storage.

Electric motors are very powertul for t heir size and develop a lot of torque at low revs. This allows them to be packaged easlly on the axle or at each wheel an d al so ellminates the need fora conventional transmission. The fina l drive (shafts) and differential ca n be attached directly to the motor through reduction gears.

COOLING ·

ELECTRONIC CONTROLLERS

Although electric systems are far more efficient than internai combustion engines, they stili generate heat which needs to be dissipated.

The energy from the power source (batteries, fuel celi or generator) must be processed and fed lnto the electric motors. The contro! systems that do this ca n be surprisingly bulky but they ca n be put somewhere conven1ently out of the way.

H-POINT 1117

SELECTING A POWERTRAIN The is the system that provides and transmits power to the wheels. Historically. the vast maJority of cars have used an internai combustion engine (I.C.E.) and some kind of mechanical system of gears and shafts that connect the engine to the driven wheels. In the future we may see a greater variety of powertams available such as electric motors wìth batteries or hydrogen fuel cells or comb1nat10ns of systems (hybrids).

What ls the mai n priorlty for the package? The funct1onal objectives will influence the priorit1es of the package. For some cars, power and performance are a high priority so the powertrain may dominate the architecture. For others the engers and cargo may be the most important cons1derat10n so the engine and transmlssion layout will be driven by pack· age efficiency (scc the apposite page).

Choosing a powertrain is often a complex task. so look closely at the functional before laymg out the engine, transmission. and fìnal drive system. G1ve the following criteria close consideration

What are the constralnts of the package? Powertrains take up a lot of space, part1cularly conventional intemal combust10n engines and mechanical transmissions. so finding room for them can be challenging. Some packages can be designed around large components but often dimensionai constra1nts will limit the size of :he cngine and limit the drive options.

Wh at '"type" of power ls required to meet the functional objectives? Some \'ehicles wil reqwre a lot of power. others only a little. High amounts of torque w1ll be needed to tow or carry heavy loads, favoring large gasoline engines or diesels. Brake-horse-power (BHP) will be a priority for performance cars, sometlmes requiring higher rewing ability and efficiency rather than outright engine slze. Luxury cars focus on qwet, smooth powertrains with good acceleration, while environmental concerns encourage powertrains that are clean and fucl-efficient. What powertrains are available? Developing 1nternal combustion engmes and transmissions takes a long ti me and is expensive. so each manufacturer generally already has their own limitcd but strateg c range from which to choose. Sometimes a manufacturer will develop an engine wrth a competitor to save costs. As the industry moves away from mternal combustion engines. it 1s likely that the manufacturers will source powertrains from their suppliers rather than develop them themselves.

119

l H-POINT

What are the tractlon requlrement.s? The final drive system distributes t he power to the wheels, so this part of the powertrain wl ll be lnfluenced by tract1on requirements. Front-wheel-dnve cars ga1n an advantage because the weight of the engtne ts dtrectly over the wheels. Rearwheel-drivo cars work well when loaded or under acceleration but usually require the transmisslon to along the center of the veh1cle. through the enger compartment. Driving ali four wheels 1s 1dea1 but a more expensive and heav1er solution. Vehicles designed for off-road use or for operation in hostile climates may require special all-wheel-
PDWERTRAIN PRIDRITIES POWER High-performance cars often use the1r engine to make a bold statement. In this package the power train dominates the side view and has a dramatic effect an the proportions, exterlor design and occupant package.

WEIGHT DISTRIBUTION S AEROOYNAMICS A mid-rear engine package works well when very high speeds and handling are criticai. This layout allows the designer to distribute the weight of the major components closer to the middle of the wheelbase. This reduces the polar moment of inertia, allowing the car to change directions more quickly. Because there is no engine up front, the hood can be lowered far better air penetration and forward vlsibìlity.

TRACTION 6 TORQUE Far serious off-road vehicles, traction takes a high priority, so durable 4WD systems coupled to motors with low speed/high torque characterlstics are a requirement. This usuatly results in a tali powertraln with a large center tunnel between the front occupants.

OCCUPANTS S CARGO Minivans require a very efficient package and put great emphasis on the occupants. The transverse engìne and transmission occupy only a small portion of the architecture. Because ali of the powertrain components are in front of the occupants' feet. th,e entire floor can be designed ftat.

ENVIRONMENT Alternative propulsion systems are being developed to help reduce harmful emissions, but their size and proportion also create new packaging opportunities. Generally. the motor and transmisslon are a fraction of the size of conventional internai combusti an engine powertrains. but the fu el SYStems (batteri es and fuel cells) are considerably larger compared with gasoline fuel tanks. Because no one component is Jarge in ali directions. the emire powertrain can usually be packaged under the floor.

H- POINT 1119

POWER CHARACTERISTICS Before specìfying the eng1ne and transmission, the power requirements should be stud1ed. The type of power wìll depend of the type of functions the vehìcle has to perform. Engine power or torque 1s measured at the (rctating) crankshaft 1n pound/foot {lb/ft) or Newton meters (Nml. This is multiplied by the engine speed (revolutions per mirute or RPM) to give the total power output which is measured in Horsepower (HP) or Kilowatts (kW).

The curve graphs (below) illustrate the different power output characteristics of various motors. For a large vehicle to have smooth acceleration or carry heavy loads uphill. 1t needs an engine with high torque. To mamtam a h1gh speed. a h1gher rewing engme is required with more brake horsepower (BHP}. Brake horsepower is the power as measured at the end of the crankshaft, at the engine; unlike horsepower which 1s the power measured at the wheels...or. h1storìcally. at the back end of a horse.

Torque

600 500 400 n. J: co

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Motor RPM x 1000

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7

TYPICAL HEAVY-OUTY TAUCK ENGINE

120

l H-POINT

Eng1ne S1ze Max HP Max Torque

7 .O liters - In-line 6 250 @ 3500rpm 600@ 2500rpm

Engine Size Max HP Max Torque

Vehicle weight Towlng capacity Accelerat1on

6000kg 8000kg 12 sec.

3500kg Vehlcle weight Towing capacity 5000kg Acceleration 0-60mph 8.0 /6.0 sec.

5.0 liters - V8 375@ 5000rpm 350 @ 4000rpm

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lt is quite simple to choose an engine based on the vehicle function. A few other factors may also affect the engine choice such as package space. cost. fuel consumption, emissions, sound and smoothness. The far-left graph illustrates a typ1cal heavy·duty truck engine. lt may be expected to carry and tow very heavy loads so it needs very high torque at low revs. The other graphs show how the relatlonship between torque and HP changes as the weight of the vehicle reduces and speed and handling become more important.

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The graph on the far right shows the dramatic difference between internai combustion engines and electric motors. They previde good smooth acceleration wìthout the resultìng high top speed. Because electric motors are so much smaller than I.C. engines producing the sa me torque, they create some interesting pacKaging opportun1ties.

Q..

300

I co

HP

-l= ..__

100-

:e

Torque

QJ

:l

E!

E!

o

l

2 3 4 5 6 7 Motor RPM x 1000

7

-

{

8

100 50

/ 2 3

4

7 8 9 l o 11 12 Motor RPM x 1000

5 6

13

14

1\

TYPICAL SMALL PERFORMANCE CAR ENGINE Engine Size Max HP Max Torque

HP

Torque

200 /

150

2.0 liters- ln-line 4 250 @ 5000rpm 120 @ 4000rpm

Vehicle weìgh 1200 kg Towing capacity n/a Acceleratìon 0...(30mph 6.0 sec.

TYPICAL ELECTRIC MOTOR Engine Size Max HP Max Torque

110 kW (peak) 220 @ 8000rpm 200 @ 0-6000rpm

Vehicle weight 1200kg Towìng capaclty nja Acceleratlon 0...(30mph 4.0 sec. H- POINT

l

121

I.C. ENGINE CONFIGURATIONS The number of cylinders and their configuration will depend on several factors. Cost, power. package space. weight distribution and vibration are the maìn considerattons behind each selection.

"honzontally opposed" or "boxer" engines. Thts not only shortens the engine out decreases its height which is very useful to help lower the center of gravity and hood or deck height.

Smaller engines tend to have fewer cylinders. which are usually arranged in stratght·hne configurattons (in-Ime). As engmes get larger to produce more power. the number of cyhnders increases, keepmg the piston size to a minimum. With an increase in cylinders the configuration may change from tn-line to a ·v· forma tion to minimize the engtne length. Some engines flatten the V out to become

Short engines (in·line fours and V sixes) are often used in transverse applications (mounted across the car) where the designer is trymg to keep the vehicle tength short. The longer engmes (straight sixes and V eights) usually need to be placed m a longttudmal onentation generally requmng them to drive the rear wheels.

122

, ...

l

H POINT

CYLINOEA & BLDCK CONFIGUAATIDNS The blocks are configured to help the veh1cle meet its functiona l objectives by eitrer improving the package, performance or comfort. Larger engines have more cylinders to minimize the size and reciprocating mass of the pistons.

e e e e e e e e e e e e e e e e e e""'

. :e

,----...

r

'-

3

""'

4

•• ••

'-

5

STRAIGHT l IN-UNE

6

6

6

NARROW V 110• -ls• t

1 1 1 ............... 8

e

e

IO

v 14s·- so·- so·1

4

12

6

HORIZONTALLY OPPOSEO IFLAT- lao ·v- BOXER)

PROPORTIONS INfLUENCEO BY ENGINE LENGTH Below are four examples lliustratmg how the number of cylinders and engtne length may 1nfluence the overall size and proportions.

TYPICAL SHORT ENGJNE APPLICATIONS

TYPICAL LDNGER ENGINE APPLICATIONS

ln-llne four or V-six engines are often used on vehicles where package efficiency or minimizing overall size is a prlority.

Larger engines are used when power is a prionty. The vehicle proportions are quite different to the cars with smaller engines. H-POINT

l 123

POWERTRAIN LOCATIONS ANO DRIENTATION The internai combustion engine has been used In Just about every possible location an::l orientation. Each configuration has its strengths and weaknesses being chosen to meet specific functional objectives like power, package efficiency, tract1on or we1ght distribution. Here are some examples of typical production-vehicle solutions.

124

Mid- Front Longitudinal Engine - RWO

Front Longitudinal Engine - AWO

Mid-Front Longitudinal Engine - RWO IRear Transmission l

Front longitudinal Engine - 4WO

Front longitudinal Engine - FWO

Front Transverse Engine - FWO

l H-POINT

Under Floor Longitudinal Engine - RWD

Mid Longitudinal Engine - AWD

Mid Transverse Engine - RWD

Rear Longitudinal Engine - RWD

Mid Longitudinal Engine - RWD

Rear Transverse Engine - RWO

H-POINT

l 125

FRONT TRANSVEASE ENGINE - FRONT-WHEEL DRIVE One of the most popular configurations for enger cars over the Jast 25 years. This is a very space-efficient lt 1S ideai for layout. which can be mounted to the body w1t1 the powertra1n and suspensìon small economy cars or large minivans where enger space is a priority. This layot.t is also used on most standard mids•ze cars. The Wldth between the tront trame ra11s can llmìt tne length of the eng1ne. making tl'is layout unsultable for luxury cars. The offset transmiss1on also causes the driveshaft length to be shortened on one side, l1miting suspension travel. The shorter driveshaft also requires the spmdie location to be close to the transmiss1on output shaft m side view so the engine tocat101 is governed by the front wheel center. This configuration is easily adapted to a parallel hybrid system w1th little overall size change.

.-transverse engine

driveshafts (unequal lengths)

transmission

frame rails

126

l H-POINT

JL f\

Steering angle limited by frame rails and universal (constant velocity) joìnts.

.... FRONT LONGITUOINAL ENGINE - AEAR-WHEEL DRIVE S 4WD This traditional layout was 1ntroduced in the late 1800s and is stili used on the vast majority of pickup trucks. luxury enger cars and sports cars. The long1tudinal orientation allows for larger (longer) engines to be installed between the frame ralls without restricting the steering angles, helping to redJce turn c1rcles on vehicles 1t can be posrt1oned with longer wheelbases. Because the eng11e 1s not linked d1rectly to the dnven for optimum weight distribut1on. The manual gear shift can a Iso be directly linked to the transmission for crisp gear changes. Final drive can be through a fixed differential or articulating solid axle. Four-wheel drive is ach1eved through a transfer case and additional driveshaft to the front axle. The longer driveshafts a Iso allow for greater suspension articulation for oft-road vehicles.

RWD longitudìnal engìne fixed <Jifferential

4WD longitudìnal eng1ne

transm1ssion

\. transfer case (4WD)

solid live axle

H-POIN

1127

FRONT LONGITUDINAL ENGINE - FRONT-WHEEL DRIVE 6 AWO This configuralion ls usually adopted by manufacturers who specialize In AWD enger cars. lt provides a lightweight. efficicnt way of getttng drive to ali four wheels. The ma m drawback of this configuration ts the long front overhang caused by the relattonship of the transmtssion to the front spindle. Unlike the transverse engine, the driveshafts are equal lengths and longer, allowing for more flexibilìty in engine location, but driveshaft are stili limtted. The fixed differential reduces the ·unsprung weight," helptng to improve handling over solid axle configurattons.

longrtudinal engine transaxle

l Long front overhang

fixed dtfferential

longitudinal engine

129

l 4-POINT

l

longitudinal mid englne

MIO-REAR LONGITUOINAL ENGINE REAR-WHEEL DRIVE G AWO This configuration is best suited to high-performance sports cars. Having the engine mounted longitudinally a1ead of the rear wheels optimizes the weight distribution for handling and comering capabJii· t ies but eliminates the possibility of rear engers. All-wheel drive 1s also possible w1th this layout.

transaxle

When the powertrain is located toward the rear of the vehicle, the coollng modules can be located remotely at the front or adjacent to the engine, usually in front of the rear tres. This will affect the location of the breathing apertures which will significantly affect the extenor design.

cooling module

REAR LONGITUDINAL ENGINE ORIVE G AWO

transaxle

Once favored by many European makers for low-powered family cars. this layout 1s rarely used today. The rear-weìght bias can make for tricky handling at the extreme, although ele::tronic traction controls and tire technology have made rear-eng1ne cars more forg1ving to dnve. Traction for acceleration though, is supreme. All-wheel drive is easy wlth thls layout. Luggage accommodatton under the hood ond

some rear enger space are possible with this configuration.

H-POINT

l 129

MIO TRANSVERSE ENGINE - REAR-WHEEL DRIVE The m1d transverse layout is often used on small sports cars. Engine size ls limlted by the track width, so these are usually found 1n llghtweight, performance cars. The powertra1ns are often adapted from front-wheel drive veh1cles. This provides great weight distribution in a car w1th a short wheelbase.

-

• .....,,___ _ _.,__ transverse engne

-

transm1ssion coollng mo(Jule

REAR TRANSVEASE ENGINE - REAR-WHEEL DRIVE Rear transverse engme layouts are applled when space (length) is cntical. lt is Ideai for micro cars where the engine size is small enough to package behmd/under the driver seat, helping to reduce the length of the vehicle m front of the driver's feet. Frontal 1mpact targets require vehicles to have free crush space between the bumper and driver's feet. Taking the engine out of the crush zone helps to create a more efficient package.

transmission

transverse engine

130

l H-POINT

MIO UNOER-FLOOR ENGINE - REAR-WHEEL DRIVE This layout is used for space efficiency mo·e than weight distnbut1on and is usuali/' applied to m1cro-utihty veh le es. The engine is packaged under the enger seat, which restncts its size and lim1ts the weight of the veh1cle. Access for maintenance can be an 1ssue. AWD 1s poss1ble through a transfer case.

longitudinal engine

transm1ssion

offset fìxed differential

remote cooling module

H- POINT

l 131

ELECTAIC DRIVE From a packaging perspective. electric drive otfers a tremendous opportunity to design more space-efficient veh1cles. mainly because the motors are so much smaller than internai combustion engines. The other components that make up the powertram can be distributed throughout the package in remote 1ocat1ons. unlike conventlonal powertrain systems which are linked mechan1cally, creating a large, hea\y assembly that has to be worked around. Another canl dlfference ls the power source or fuel. Conventlo1al cars have fue l tanks that are relatively small and can be molded to fit around other components, whereas t1e energy source for an electric system. either a battery or fuel celi, is Quite large and in the case of batteries, very heavy This can work as an advantage, lowering the center of gravity.

r. ·-·- - ·---·--,.

electric motor

l l

l

Fuel Celi & Hydrogen; Batteries controllers and cool1ng j

L ._ -·- · - · - - _j

l

,--·-

ll .

·-·-·\_

Fuel Celi & Hydrogen/Batteries controllers and coollng

L._. _ _____ _;-

132

l

H-POINT

1 ·

.

_j

electric hub motors

... HYBRID DRIVE SYSTEMS These systems are seen as a stepping-stone toward future all-electric powertrains. They mlx the attributes of internai combustion engines and electric motors to provide a fuel-efficient powertrain with a long range. Although they have more components than conventional systems, the engines car be smaller because of the extra torque provlded by the electrlc motor. gasoline/diesel tank

longitudinaii.C. engine

RWD

gasoline/diesel tank

PARALLEL HYBRIDS

transverse l.C. engine - - 4-l starter generator

r---L__J

The internai combustion engine and electric motor (starter generator) are linked mechamcally and the power IS fed to the driven wheels through the transmission and final drive system.

. .

FWD

L_j

transmission

gasoline/diesel tank

longitudinal I.C. engine

r

electric motor

SERIES HYBRIOS The generator ls turned by the internai combustion engine and the electricity ls fed to the electric motor(s). Thls type of hybrid system offers packaglng advantages by eliminatmg the need fora mechanical transmission and driveshafts as well as dfvorclng the internai combustion engire from tIle wlleels.

H-POINT

l 133

FUEL ANO ENERGY STORAGE Traditionally, fuel tanks have been considered part ofthe "chassis" group of components. but with advanced alternative propulsion solutlons, storing the energy or fuel ìs now often the respons1blllty of powertraln groups. Whether the powertram uses a trad1tional 1nternal combustion engine or is dnven by an alternative electric solution. the basic principles of storage remain similar. Wherever possible, the fuel tank, batteries or fuel celi should not, in themselves, unduly lnfluence the overall package of the vehicle. The fuel tank should be located wherever there is a natura l open volume away from other key elements. For examp e, most enger car fuel tanks are located under the rear seat in an open space created by the rear occupant's pasture. Always look fora void space in the architect ure and try to piace the fue l there. Because the fuel storage usually takes up a significant volume, it should always be included in the initial package ldeation sketches so that lt does not become an afterthought. Next, consider safety. This ls actually the most important part of fuel packaging and should not be overlooked. Unlike other elements 1n the package, the fuel is combustible. so if the vehicle is in a high speed collislon or rolls over, the fuel should remain lnside the st orage container and away from the occupants. on the other slde of a firewall, such as a metal f loor or bulkhead.

Consldering these three objectives usually pushes the fuel to an inboard, under· floor location often under the rear occupants' seat . lt is always good to look for the strongest areas of the body structure and locate the fuel inboard of these. The main frame rails and cross will help to protect the fue l from impact. The amount of fuel required is going to depend on the functiona l objectives. Range and fuel consumption wlll be the two main factors. but packaging space may also limit fuel capacity. Benchmark existing vehicles for ideai fuel volumes. Batteries generat e heat as they provide energy and require cooling, so additional space should be allocated for cooling solutlons. Hydrogen for fu et cells is stored under very high pressure (10,000 psi) and the tanks must be designed and located to avoid rupture on impact. Traditional fuel tanks wiiÌ also requlre some space for the fuel pump and measurement systems. The examples on the apposite page show some typìcal existmg fueljenergy starage locations.

The fuel source, whether liquid, gas or solid, is dense and often heavy. In the case of gasoline or diesel, the mass of the fuel tank will vary as the fuel is consumed. On sports cars. this may lead to a noticeable variation In handling ifthe fuel tank is located in the wrong piace. Keeping the fuel as low as possible and toward the center of the vehicle ls always the objective.

134

l H-POINT ...

.

VARIOUS FUEL STORAGE LOCATIONS ENGER CARS

MINIVANS & TRUCKS

suvs

The most common locatìon for enger car fuel tanks is in the space under the rear occupants' seat. In rear-wheel drive cars. the tank has to straddle the prop shaft.

Minivan fuel tanks are quite large but usually package easily under the long high floor structure. Stowing seats can be an obstacle in some vans.

SUVs have been forced to move their fuel tanks from under the rear cargo floor to in front of the rear axle to comply with rear impact safety legislation.

SMALL SPORTS CARS

LARGE SPDRTS CAAS

AEAA-ENGINE SPORTS CARS

lt is common to locate the fuel behird the driver in small front or mid·engine sports cars to help wìth good wefght distribut1on.

Larger sports cars may package the tank on top of the rear axle to help shorten the wheelbase.

Packaging the fuel in front of the dash is uncommon but helps to dìstribute the masses in rear-engine sports cars.

ELECTRIC VEHICLES

ELECTAIC SEDANS

Due to the large but low profile proportions of electric powertrains, it is common to

package the whole system under the floor. This results in a high occupant package which may be desìrable in some vehicles.

With the reduction in the size of fuel cells and batteries, lt 1s possible to package an electric propulsion energy system in the tunnel and varìous locations to allow fora low enger conpartment floor.

GENERAL INFORMATIDN Ali of these fuel storage solutions will be molded to fit into as small a space as possible. and mounted symmetrically about the vehicle centerline (where possible)to improve weight distrìbution. Benchmark existing vehicles to understand the typical range and fuel consumption versus the tank capacity or battery

One small des1gn feature to consider is that the fuel filler will need to be close to the tank location. H-POINT

l 135

WHEEL & TIRE SIZING When the destgner chooses the initial wheel and tire package, the main objecttve 1s to get a oombination that works both aesthettcally and functionally. The norma l tendency is for designers to want the largest wheel diameter with a very low profile tire. For most cars and trucks this 1s not good.

Tires are manufactured in incrementai sizes described with a formula for the tread width, sidewall aspect ratio and wheel size. The outside diameter is calculated from this. Light-truck tires use a different formula, part of which includes the O. D., simplifying the process.

l-or a parttcular vehtcle, the outslde dlameter (O.D.) ot the t•re wìll be hmited, so looking at this dimension is the starting point. Next. the sidewall depth should be established based on the loading and performance targets. The wheel diameter will be derived from these two factors. The tire wldth will depend on traction requirements for acceleratlon, braking and cornering. Rolling resistance, cast and package space should also be considered. lt is not uncommon for high performance cars to have different sized front and rear tires to provide more traction at the driven wheels.

Tlre specifications are somewhat complex because they are a mlxture of millimeters. inches and a percentage. After estimating the t ire dimensions. the diameter should be adjusted to a correct available size calculated from a typical tire specification as shown on p. 141.

Approximate wheel and tire sizes should be established quite early on in the design process, usually after the prellmlnary occupant package has been set up. Additionally, the suspension travel and steering angles should be predicted to determtne the tire envelopes, which identìfy the total volumes occupied by the tires during extreme use.

138

l H·POINT

Sidewall helght is governed by load carrying requirements, ride comfort and handling. Trucks and SUVs will have tali siclewalls to help increase their gross vehi::le weight (GVW) and protect the rims on rough terrain. Low-profilé tires are preferred on sports cars to minimize sidewall flex during cornering. Narrow tires actually work better in snow, so a winter ti re package may be smaller than the one for summer. Styling also plays a big part in wheel and tire size so getting the wheel diameter to work with the proportions of the car may be the fina l determining factor o n the exact wheel and tire package.

TIRE SIOEWALL HEIGHTS IASPECT RATIOJ

TAUCK Ei SUV TIRE PROFILE

ENGER CAR TIRE PAOFILE

SPORTS CAA TIRE PROFILE

Vehrcles that are designed to carry heavy loads or travel over rough terrarn requrre a taller sidewall to distribute the load and protect tre rim from rock damage.

For cars that reqUire a comfortable ride. an average srdewall height is advisable. provrding a baiance between comfort and handling.

Performance cars will sacnfice comfort to improve comenng capability. The low profile tire ·educes tire wall deftection and allows for a larger diameter wheel whrch provides roorr for a larger brake rotor, rf requrred. Il also improves the extenor appearance.

The drawback of a taller aspect ratio is sidewall flex that will be detrimental to handling bJt will improve ride comfort.

Thls configuratlon is usually less expensive than a larger wheel and low profile tire combination.

A drawback is that the mrnimized sidewall height leaves the wheel rim vulnerable to damage from curbs and potholes. Also, the total weight of trre and rim will be hrgher, which increases the unsprung werght. This will counter against the 1andllng benefits.

H· POINT

l 139

TIRE TREAO WIOTH Note: The actual profile width will be approximately 10mm wider than the specified tread width.

,..

.,

BOLT PATIERN The bolt pattern will vary in diameter and number of bolts. ldeally the spoke design will be compatìble wìth the bolt pattern unless a center cover is incorporated into the wheel design.

SPINOLE CENTER POINT The major reference datum for the wheel and ti re package.

RIM WIOTH

TIRE SIOEWALL HEIGHT

'

WHEEL RIM OIAMETER

WHEEL FLANGE OIAMETER

l l l

·- ·$--

Note: The •·visible" flange d 1ameter is larger than the nm diameter. Example, a 22" wheel has a flange diameter of about 23.4".

1

l l

STATIC LOAO RAOIUS ISLRJ This dimension is calculate from half the

TIRE CRUSH :15-25mm, depend-

nre O.D. minus the "crush: lt determines the spindle height from the ground line.

lng on sìdewall height & loadlng.

,...... 140

l H-POINT

TIRE OUTSIOE OIAMETER 10.0.1

WHEEL FLANGE DIAMETERS The flange diameter represents the actual visible wheel sizes. Note: the rim diameter (measured in lnches) is 30-35mm smaller than the flange dlameter. This difference ls shown ln this chart. rim diameter (inches)

12 13 14 15

16 17

flange diameter (m m)

333 358 381 413 440

18

471 497

19

522

20 21 22

547

568 594

Sldewall Aspect Ratto as a perc:entage of the tread width changlng In lncrements of 5%

enger Car Deslgnation

Speed rating and constructlon

Tread Width in mlllimeters.

r TI"S"'

-C

Wheel Rim Oiameter In lnches. changing in r increments

P 215 50 R 16 enger Cars Tire Example Llght Truck Tlre Example

31 x 10.5 16 LT

( Tlre Dlameter in lnches

Tread Wldth in inches

Wheel Rim in inches

Light Truck Deslgnatlon

Tire Size Formula To Calculate the O.D. in millimeters for the 215 50 R16 Tlre (215 x 50% x 2 ) + (16 x 25 .4) = 621 mm (Tire O.D.)

H-POINT

l 141

BRAKE PACKAGING SECTIONAL VIEW THROUGH THE FRONT WHEEL. TIRE. SUSPENSION B BRAKES Wheel design is heavily lnfluenoed by the chassis components they are bolted to. Suspension arms, steering geometry an d brake systems ali push the wheel spokes outboard.

tire in fu i jounce

The section shown right, illustrates how the steering axis ls set up to minimize the "scrub radius." The steering axis es through the bali ts which subsequently force the brake rotor and caliper out past the center of the wheel.

tire profile

Opposite page: note how the brake caliper in the section limits the amount of "dishing" that can be applled on the spoke design for the front whee . upper bali t standard rim profile

/ knuckle suspension contro! arms

lower bali t - - - - - - -

steering (kingpin) axis

curb ground llne

142

l H-POINT

JL

scrub radlus

SECTIDNAL PLAN VIEW THROUGH THE BRAKE CALIPER S SPOKES

Brake caliper

Suspension contro! arms

The brake calìper is often used as a design clcment on cxotlc sports cars. lt is located at the opposite side of the splndle to the steer·ng arm. lt lim1ts the spoke design on the front wheels. More dishing ca n be ach1eved by using a wider rim or 1ncreasmg lhe scrub radius, but these may be detrimental to performance and handling.

- - - - - Backside of the spoke, set up by the brake caliper package

Knuckle

The spoke th1ckness is determined by structura1 requirements.

\ Steeong ,.ck

H- POIN l

l 143

TIRE ENVELOPES These 30 surfaces represent the sweep of the ti re proftie in turn and jounce, with clearances & tolerances added.

PLAN VIEW .... ,

1

/

TURN

..

'

.

'"-..,_ l / . .

'

\__/·

JOUNCE

.

.

tlre envelope

!( Il

. t-·--- --·-·

\

.

J

/ . l '"-.... .

(Suspension Travel)

.

!

.

'

l

l H-POINT

FRONT VIEW

·........_;

/

/

l

tire outside diameter (OD)

".

l l l

\\

'l

.--·-·-·--4·- -- ·- · .

i\

"-......_____J_____.. . . . / 1

144

,-

.

SIDE VIEW

' - - splodle ceoteo (ma1n reterence datum)

J-.

SPARE TIRE PACKAGING Hopefully, spare tires will soon be a thing of the past and run-flat or airless tire technology will eliminate the need for vehicles to have 5 wheels. Unti l then, most cars and trucks will have a full-slze or space-saving spare packaged somewhere in the architecture.

may be determined by the size of the spare. Many customers want a full-slze spare, and if the vehicle has a large ti re O. D., packaging this may be challenging. Often space-saver tires are used, but these can be no smaller than 80% of the origmal dlameter to prevent wear on the differential.

The example shown l.Jelow is a lypical sedan spare-tire package beneath the trunk load floor, between the rear suspension and bumper beam. Thìs is a common location, allowing easy access in the event of a puncture. The rear overhang

Vehicles with higher floors (minivans and trucks) may package the spare further forward under the enger compartment floor. SUVs often mount the spare on the rear swing gate.

rear cross member rear suspension package space bumper beam

-$fuel tank - /

"- exhaust system

H-POINT l 14S

EC TIRE COVERAGE REQUIREMENTS European legislation requires that the tires must be inboard of the body work in the zones shown below, 30° forward of the sptrdle center and 50° rearward.

146

l H·POINT

TI RE-TD- BDDY RELATIDNSHIPS

l.

The opening between the ti re profile and the wheel arch will vary greatly depending on the function of the vehic e. This is maìnly due to the geometry, jounce travel and tolerances built into each suspension system. Large openings and inset wheels are bad far aerodyramics and are not usually regarded as a desirable styling feature.

l. TRUCKS 6 SUVS Suspension will have long travel (125-150mm+) and ifa solid axle type is used the ti re will move up and down vertically without camber change when the vehicle is loaded. Because of thls, the ti re sidewall will be set In from the body an d have a large open space at the top ofthe tire.

TAUCKS 6 SUVS

2.

a.

ENGER CARS

These will have less travel (100-120mm) and often employ suspens1on systems that cause camber change. The relatlonship between tire and body can be reduced substantìally ln these cases. lf tralllng arm or Mherson strut systems are used, the tire will need to be set in more.

ENGER CARS 3.

3. SPORTS CARS These will often have negative camber at curb attitude and this will increase duringjounce travel. The travel is usually limited (75-90mm) so it is easier and more desirable to keep the openings to a minimum.

SPOATS CAAS

H-POINT

l

147

STEEAING 6 TUAN CIACLES Steering objectives should be addressed at an early stage of the packaging process. The turn-circle requirements will have a major influence on the package. The diagrams below show the elements thal contro! the turn circle. The front trame rails lhat run between the engine and the tires inhibit the steering angle. In the 1llustrat1on below, if a larger (transverse) engine is required the track wìll have to be widened to maintain the same turn circle.

The two factors that contro l the turn circle are the wheelbase and the turn angle. Long-wheelbase vehicles wl li require a greater turn angle. This ls often made possible by the longitudinal powertrain layout which allows the front frame rails to be moved inboard. Trucks with an extremely longwheelbase may also require the rear wheels to steer to get the turn circle to an acceptable diameter.

Turn circles are usually about 10 meters for small cars and 12 meters for larger cars. Large trucks and limousines with long wheelbases may have turn circles up to 15 meters.

Power'.rain

148

l

H·POINT

STEEAING SYSTEMS Two types of steering systems are commonly used: 1 ) rack and pin1on. and 2) rec1rculatmg bali. The steering mechanisms are located just behind or forward of the front spindle, (creating front or rear steer). The steenng wheel is directly linked to the mechanlsm through the input shafts or steering column, which is divided into severa! segments and angled to reduce steering-<:olumn movement in a fron tal impact. Rack and plnlon is the most common system. and works wlth most vehicles. Rec1rculating bali systems are usually applied when a lot of suspension art1culation is required. The long track rods help to reduce ''bump steer· (caused by the difference between the suspension and steering geometry) wh1ch results in the turn angle changing as the suspension travels in jounce or rebound.

AECIRCULATING BALL

Below are three applications of the systems Designers should note t1at the steering mechanism attachment to the knuckle w1ll affect the location of the brake cali per which is often used as a design element. Note: the steering systems may not feature in the initial package, as they rarely affect the exterior surface.

AACK 6 PINION lunder the enginel

RACK 6 PINION lbehind the enginel

Steenng rack

Steering rack

Steering dam

Solid Uve Axle

Steering Lìnkage

_r

l Long1tudinal

Engine AWD

: ì l

! !

Transverse J E'lgine FWD

........._ Longitudinal Engine RWD

iJ

n

l

l 'l

ti\.-

Pitman l

\

Steenng Box

/

Steering axis

\

)

Steering axis

L Steering column

Steering column Steering axis /

L

brake caliper

brake cahper

Steenng column

H-PO Nl 1149

INTROOUCTION TO SUSPENSION SYSTEMS Choosing the type of suspension system that works with the functional objectives of the vehicle should be done at the ideation phase of the package. The two maìn objectlves for any suspenslon system are to previde ride comfort to the occupants and keep ali four tires in with the road for optimum tn:ICtion and handling. These can be achieved in many different ways. The effect that each kind of system has on the tire envelopes and adjacent package compo'lents should be understood so that the initial package study can be set up with these in mind. Here are some functions that will determine the type of mechanism and spring,tdamper unrts to employ: 1) Heavy Load Carrylng

travel and art•culat1on capabilities. Often solid axle confìguratlons are used. These span the entire width of the vehicle and require lots of clearance to tt'e floor and underbody structure. Sports and race car suspension rs crit1cal to handling, so the geometry cannot be compromised and is set up around the Ideai plvot points. Golf carts on the other hand wili empioy the cheapest, smaliest systems that can be found. Typlcal priorìtles for different vehicle types are shown opposite. On pages 154-163 there are some eKamples of various systems, their applications. advantages and disadvantages. The marn thrng to note is that they each work well in several situations. so if your fìrst choice does not fit your package well, there wili be other options.

2) Travel & Artlculat lon 3) Handllng

PITCH. YAW & ROLL

4) Comfort

Thesc three dynamic conditions happen durlng acceleration, braking and cornering. They are reactions to inertia. which cause the vehicle to rotate around the center of gravity. Generally speaking, minimizing these will improve the handllng and in some cases, the ride comfort. The best way to contro l alt three is to reduce the vehicle mass and distribute it evenly, as close to the vehicle center as pos· sible and low to the ground. This reduces the "polar moment of rnert1a." Once the aerodynamics and major components are set in the package, the only way to further contrai the pìtch. yaw and roll IS with suspension desrgn and tire choice.

5) Cost 6) Package Constraints A large chunk of the n•tial package process 1nvolves setting up the relationsh•P between the t•res and the occupants This ca1not be done accurately until the • Jounce and Tum· envelopes (see p. 144) have been established by the suspensron engineers. These envelopes define the swept area of the ti re profile, as the suspensron articulates and the steenng angles change. Full jounce and full lock condrtrons are usually the most 1mportant, although these two extremes do not always occur at the same lime.

YAW

There are many different systems. each having positive and negative attributes depending on the application. Each is designed with three mai n elements, namely the spnngs, that the weight of the vehicle and absorb the road shocks; the dampers or shock absorbers. that ensure the springs do not overreact; and. the mechanism that controls the geometry. For each suspension mechanrsm type there may be several spnng types which could work. Far example, short- and long-arm (SLA) suspension can be sprung with co11s, torsron bars or leaf springs. Sohd axle types can be ed by coils, leaf spnngs or air bags, depending on the application and package constraints. Some systems will package very well and almost disappear in the initial package, others will be massive and have a great influence on the architecture. Truck and off-road vehicles, for example, will require very strong components with long

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PITCH

SUSPENSION SYSTEM ATTRIBUTE PRIORITIES Each vehicle will have ìts own set of priorities for both front and rear suspenston. The systems should be matched up to these criteria.

cost package

\

handltng

cost package

handling

\

comfort loading travel

loading travel

cost package

comfort handling

travel comfort

cost package

comfort handling

travel loading comfort

cost package handling

comfort cost

cost loading

cost package handling

loading comfort cost

loadlng cost

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SUSPENSION TYPES Ffom the designer's perspective, it ìs important to know why a particular type of system will be applied and how its configuraticn will affect the vehicle's proportions and package. Understanding the geometry ts not so tmportant, but 1t helps to know the effect that the mechanism will have on the wheels as they travel in jounce (up) & rebound (down).

The illustratlons below show some of the many systems currently in use. These are described in more detail on the followtng pages. Notice that they are divtded into non-independent and independent. Generally speaktng, the non-independent systems are used on vehicles that carry heavy loads or reqwe extreme arttculation tn off-road environments. The independent systems are more sophisticated and provide better handling and ride comfort.

SOLID AXLE l LEAF SPRING

SOLID AXLE l TRAILING LINK

LINK l CDIL

TRAILING ARM l CDIL

NON-INOEPENOENT SYSTEMS

154

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....

MHERSON STRUT

CHAPMAN STAUT

SLA l COIL

MULTI-LINK l COIL

INDEPENOENT SYSTEMS

H-POit.'T

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ISS

SOLI[] AXLE SUSPENSION SYSTEMS Often used on utility vehicles that are designed to carry heavy loads. Most commonly used on rear suspension. but occasionally on the front. "Live· axles contain the final drive system (differertial and driveshafts) Beam axles are applled 1f drive is not reqwed. The advantages include low cost, strength, long art1culation, efficient packagmg. consistent ground clearance and adjustability. The main drawback is compromised handling due to the amount of unsprung weight.

panhard rod

FRONT - SOLIO UVE AXLE l COIL SPRINGS (NON- INDEPENDENTJ Thls system will often be applied to extreme SUVs, prov1ding 4WD, strength and articulation. When sett1ng up the package, allow for at least 150 mm of jounce travel for the axle assembly. The axle will be located directly underneath the engine. whJch wlll be mounted high enough to allow for U1e suspension travel. Th1s will affect the driver's eye point which should be located high enough to see over the hood.

differentlal casing

.... solid live axle shock absorber 1 damper coil spring

steering axis

/ s p i n dle

/

contro! arms 1 lhe position and rotation of the axle and knuckles)

156

ceoterlioe ..........

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...

LOADING Ei OYNAMIC CONDITIONS

Tires are always perpendicular to the ground and axle centerline at curb weight

CURB

Tires remain vertical dJring loading and cornering

FULLY LOADED GVW

REAR - SOLIO UVE AXLE l LEAF SPRINGS lNON-INOEPENOENTJ

CORNERING l ROLL

REAR - SOLIO BEAM AXLE /LEAF SPRINGS INON-INDEPENOENT) leaf springs ( the vehicle's we1ght and control the axle posi tion and rotation)

panhard rod (controls the lateral locat1on of the axle)

differential casing

solld (beam) axle

shock absorber;

The solid beam axle center can be lower than the spindle height. helping to lower the vehicle's floor. The leaf springs package efficiently along the body frame rails, but require a long rear overhang to accommodate their length .

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l 157

TRAILING ARM SUSPENSION SYSTEMS Often Jsed on small cars because it packages ef· ficiently in light vehicles with short rear overhangs and most conflgurations provide space for the spare tire. This system works well when loaded because the camber change is very llmlted. The swing arms are often linked by a twist beam Which can be located along the pivot axis or the spindle centerllne. These reduce body roll and the latter will help the tires remai n vertical during cornering.

REAR - TRAILING ARM l COIL SPRINGS IINOEPENOENTJ

pivot axis

REAR - TRAILING ARM l TORSION BARS SPRINGS IINDEPENOENTJ

trailing arm

coli spring spindle centerline ___. -----

shock absorber

torsion bar twist beam (antì rolljsway) shock absorber 1 damper Using torsion bars and horizontal shock absorbers helps to lower the rear floor, improving cargo space.

traìling arm

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One drawback of traillng arm suspension is latera! flexing during cornering. Latera! llnks can be added to the system to improve handling. Triangular trailing arms also help to minimize flexing.

LDADING G DYNAMIC CONOITIONS

l The tires may be vertical nr have some camber added at curb attitude.

CURB

The tires may remain parailei to the vehicle centerline ::>r perpendicular to the road Nhen cornering, dependìng ::>n lhe design.

FULLY LOADEO GVW

REAR - SEMI TRAIUNG ARM l COIL SPRINGS IINDEPENDENTI

COANERING l ROLL

REAR - SOUO BEAM AXLE. TRAILING UNK l COIL SPRINGS INDN-INDEPENDENTI panhard

coil spring coil spring

solid axle l twist beam

/. trailing arm tailing arm

trailing arm plvot axis (ax1s to prov1de camber change}

/'

/'

/

./· /.

/

Semi trailing arms create a sllght camber change during cornering which can optimize the handling attributes during hard drìving. A sol id beam axle ca n be mounted to trailirg arms to create a slmple lightweight system. A panhard rod or Watt's llnk controls latera! movement of the beam. H-POINT

l 159

STRUT SUSPENSIDN SYSTEMS Very common front suspension on enger cars. Mherson struts incorporate the steering ax1s 1nto the strut centerline. reducing oost. This system packages well wlth transverse engines but usually requires a high fender to fit the spring above the tire. Chapman struts are used on rear applicatrons where steering is not required.

low strut designed to reduce fender height

pivot axis

FRONT - MHERSON STRUTl CDIL SPRINGS (INDEPENDENTJ control arms

/

r /

steering axis

coil spring

steering knuckle

anti-roll 1 sway bar

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LDADING & DYNAMIC CONDITIDNS

l Slight camber change occurs under loadlng and cornering. Body roll needs to be minimized to maintain tlre with the road.

The tires may be vertical or have some camber added at curb attitude.

CURB

FULLY LOAOEO GVW

REAR - CHAPMAN STRUT l COIL SPRINGS IINDEPENDENTI This system can be very simple, inexpensive and lightweight (as shown). lt also packages very efficiently. lt is ideai for lightweight, entry-level sports cars. More robust versions ca n be applied to larger, more capable cars and SUVs. In these applications the hub may be attached to the control arm rather than the strut.

COANERING l ROLL

chapman strut ;coi l spring trailing link hub (mounted to the strut)

lateral links

anti-roll / sway bar

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SLA 6 MULTI-LINK SUSPENSION SYSTEMS

upper contrai arms

These are the most sophisticated systems, mainly used on high-performance and luxury cars, at both front and rear. Trucks and SUVs often use the SLA (short and long arm) system for their front suspenston. The geometry of the contrai arms is destgned to contro! camber change to mamtam each t lre·s patch as the body rolls during cornerlng. Packaging the lnner pivots axis can be a challenge on some vehicles. Note that the upper contrai arm can be mounted in a low or high location dependlng on the ideai attachment posìtìon and drive shaft confìgurations. Spnngs are coils but torsion bars and leaf springs can also be used to suit the applìcatìon. On open-wheel race cars the coils are often mounted longitudìnally ìnside the body to tmprove aerodynamics. These are actuated by a push rod and beli crank.

FRONT - SLA TORSION BAR IINOEPENOENT)

ptvot axts

pivot axis

PIVOt 8XJS

FRONT - SLA COIL OVER SHOCK IINDEPENOENTJ upper contrai arms

upper contro! arm

lower contrai ;:um

torsìon bar spring

coìl spring over shock absorber

steenng axis

steenng knuckle anti-roll l sw3y bar

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LOADING 6 DYNAMIC CONDITIDNS Camber lncreases as the veh1cle is loaded. When the body rolls during cornering the controlled camber change cumpt:msates. keeping the tire patch on the g-ound.

Tires can be set vertically or w1th camber at curb attitude.

CURB

FULLY LOADED GVW

CORNERING l RDLL

REAR - MULTI-LINK l CDIL SPRINGS l INOEPENDENTJ

fixed d1tferent1al coli spring

hub assembly driveshaft

suspens1on cradle (rubber mounted to the body)

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INTADDUCTION TO BODY STAUCTURES The body is one of the most complex assemblies of a enger vehicle. consumrng a large portìon of a project's resources, both manpower and investment. Besldes being a complex piece of engineering. it is al so 1he element most tred to the vehlcle's overall architecture and its appearance. The body structure and outer skin have four main functions: 1) Protect the occupants and cargo. 2) Provlde attachment polnts for ali other major components and manage the stress between them. 3) Provlde an appealing appearance and lmage for the product.

rails, cross . etc.) are developed in a series of typical sections which are strategically cu1 through the main st ructure. The path and size (cross-sectronal area and matenal thickness) of each section rs determined by a structural analyst. He or she will use computer applrcatrons to ensure t he body meets ali of the requirements for torsional stiffness, durabillty, vlbrational frequency and weight. The illustration on the opposite page shows a very primitive load path diagram which may be used to set up the structure. The bodies of nearly ali mass-produced cars, minivans, trucks and SUVs are made from stamped steet although this mrght change as werght reduction becomes more and more rmportant to rncrease energy efficiency. Some vehicles substrtute steel for pressed aluminum and, in some cases, extruded aluminum sections.

4) Provlde an aerodynamic form to lmprove performance and reduce nolse.

A car or truck body can be broken down into three main groups of assemblies, namely: the underbody, upper body and closures. The underbody consists mainly of the floor s and dash structure whlch are stlffened by a number of box sections to form a substructure. These box sectrons compnse the main longitudinal frame rarls, the sills and the cross . The powertrain and chassrs components are attached to this substructure whlch also serves as the primary crash structure, running out to the extremrties of the body. The upper body can be thought of as a framework surrounding a series of apertures and ing the outer skrn of the vehicle. Each aperture or opening is designed to provide access into the vehicle or visibility out of il. The closures include the doors, hood, and trunk lidjtallgate. These represent a large portion of t he exterlor surface and feature extensively in t he early packagrng studles. The combinatron of box sections and "shear· s serve to meet the four functional requrrements listed above. The bulk of the work is done by the box sections (or beams) that are designed to withstand the enormous stresses that a vehicle wrll endure throughout its lite. The desrgn of the beams (prllars. sills,

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In addition to the box sections, cont01.red s !floor. dash. roof, wheel houses. etc.) close off the structure, creating a weatherproof and fireproof compartment for the engers and cargo. These an d some of the glazing s also ad d to the structural integrity of the body and manage shear loads. The closures such as the hood, trunk lid and tailgate do not add much t o the dynamrc structure. but they can play a major role rn crash protection. These are of:en made from materials that dìffer from the marn structure (such as plastic) to reduce weight or provrde attribu1es such as dent resistance whife improving formabrlity. Bumper or fascia s are usuali) made from damage resistant plastrcs to meet low·speed 1mpact requrrements whrch are mandatory rn many markets. Using plastrcs a Iso helps to form shapes that are difficult to create in meta l. lt also allows severa! components such as grills, lamp housings, scoops and badges to be made in one part, helping to reduce complexity and assembly ti me. The remaining exterior s serve only to create an appealing. aerodynamic ex terior form. The other exterior features and components such as glass, lighting, breathing apertures and license-plate pockets ali need to be considered in the development of the body and its typical sections.

LOAD PATHS This simple node diagram is created arourd the package by the structural ana lysts. The mam load inputs from the suspension mounts and crash systems create the major load paths wh1ch thread through the body. From this the required cross-sectiOnal areas of the mam box sections are calculated. These sections feature prominently in the vehicle package. Each box section or structural mat be subject to one or more of tne forces shown below.

'["

. ...

.=·-·-·-·-·

TWISTING

BENDING

COMPRESSION

"}

SHEARING

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TYPES OF BODY STAUCTUAES

UNJBOOY

BODY ON FRAME

The most efficient and cost-effective type of construction process for mass-produced cars, mtnivans and SUVs. The structure is made from steel or aluminum s (0. 7-2.0mm thick). The s are stamped into shape and lhen spot welded together to form a series of box sectlons and contoured s. Exterlor s can be made of metal or plastic depending on low-speed impact requlrements.

This type of construction is often used on pickup trucks and rarge SUVs, helping to manage heavy loads and drive over rough terrain. Il also provides strength for tncreased towing capacity. The powertrain, suspension and main body are ali mounted separately to a high-strength frame on rubber isolators to lmprove the ride quality, noise and vibration. Sigrifì cant drawbacks of thls type of structure are increased weight, higher floor height and poor torsional ngidity, which is im· portant for good handling and road holding.

Unitary body, less doors, structure made from steel stampings that are spot welded togcthcr.

A high-strength steel truck frame that s the unitary cab and bed assemblies mounted on top. This combination creates a st ructure that ls very tough and durable. albeit poor in torsional rigidity.

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SPACE FAAMES

Space frames are typically used for low-volume-production performance cars, wrere high stiffness, weight and low tooling investment are paramount. The space frame acts as the structural "skeleton" to which the rnechanical components and

outer. visible skin s are attached. A space frame can be constructed from a variety or combination of materials such as steel tubes, aluminum extrusions or plastic composites.

This extruded aluminum alloy space frame is welded or bonded together to form a stlff lightweight structure where much of the stress is managed by the sii l sections. This type of design is Ideai for mid- or rear-engine cars that do not requlre a tunnel for driveshafts.

Jn this space frame solution, high-strength steel or aluminum alloy tubing is welded together to form a "backbone" frame where most of the torsional rigidity comes from the tunnel structure. Shear s are added to stlffen the structure and close off the floor and dash. Plastlc outer s complete the body assembly. This type of design lends itself to front-engine, RWD cars that requlre a tunnel for the transmission and driveshaft.

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169

TYPICAL ELEMENTS OF THE BODY STRUCTURE

UNDERBOOY ASSEMBLY

Rear Cargo Roor Rear Wheel House

Rear Rails

BODY. LESS OOOAS. ASSEMBLY

Roof (Not Shown) Roof Rail Windshield Header Cross C Pillar Cowl

l

Plenum

Dash 1 (FireWall) Rear Quarter

Front Cross Memberl Radiator

S ii l

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Front Wheel House

Englne Box 1 Bay

EFFICIENT DESIGN FOA HIGH- SPEEO IMPACT The front-end structure ìs designed to crush at a specific rate to absorb energy. Clear crush space around any solid component s such as the englne, transmìsslon and steering ls requlred to a 40mph impact test.

The enger compartment ls very rigid to protect the occupants from being crushed dunng a high-speed impact or rollover. After the impact, the doors should st ili open.

The rear-end structure ls designed to crush in a simllar way to the front.

Protectlng the occupants from lnjury ls the highest priority when deslgnlng a vehlcle.

The most stressful event that a human body wlll endure is a high-speed crash. Meeting various government impact testìng requirements and consumer-group standards provldes a set of clear objectìves for the structure. These tests involve the vehicle being driven into barriers at specific speeds or being hit with test devices in various zones with specitìc forces being applied. After each test, rneasurements are taken on the body structure and crash dummies to confirm the integrlty of the design. Visit www.euroncap.com for more information on this. The main enger compartment is very rigid and 1s configured to rema1n intact after a serious accident with little or no deformation. Tre front and rear structures are designed to crumple at a controlled rate to absorb energy, thereby reducing trauma to the occupants. Many of the key elements of the crash structure feature frequently In the typical sections that run through the package. Note that many of the main structural elements such as the sills, rails and cross are designed to be as straight as posslble. By belng straight, they can manage very high (compression) loads efficiently a long their axes. Latera! under-floor cross are designed to meet side impact requirements.

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171

SAFETY REGULATIDNS Many elements in the package are controlled by legislatron, none more so than the body structure and exterior features such as lighting, bumpers and license plates. Each market (country/region) has a slightly different set of rules and guidelines, whlch for the most part serve to make vehicles safer. Because cars generally serve the same purpose ali over the world, similar safety regu latlons apply everywhere.

carried over from an earlter era. In additron to governmentallegislation, organrzations tike the New Car Assessment Program (NCAP) serve to provide rmpartial crashworthiness information to customers. They conduct comprehensive crash tests and report to the consumer exactly how each vehicle performed. They lssue a star rating to each mode l and most manufacturers strive to achreve the hrghest "5-star rating." Visil www.euroncap.com for more information.

Additionally, consumer groups keep customers very well informed about safety rssues, so most manufacturers willlook to exceed the local safety regulatrons to gai n an advantage in the market. To sell vehicles 1n global markets. each product will ha\e to meet the strictest regulations in ali countries.

Japan LegislatiOn is similar to Europe due to similar traffic-
The governing bodies of the three maJor car-manufacturing countnesjconti· nents-USA, Europe and Japan-set most of the signrficant standards that automotrve manufacturers strive to meet.

Worldwlde Most other countries in the world wrll look to these governments to establish their own standards. They may al so use lnternational Standard Organìzation (ISO) standards to help regulate products on therr roads.

North America The Department of Transportation has an organization called the National Highway Transportation Safety Association (NHTSA). They establish the Federai Motor Vehicle Safety Standards (FMVSS). These govem the desrgn of cars in the USA. Canada has a similar set of standards, the Canadian Motor Vehicle Safety Standards (CMVSS). These vary fro111 tlte US tegulations, so most American cars are designed to meet both sets of requrrements. The Environmental ProtectJon Agenc:t (EPA) atso sets standards to help maintain and improve the environment. One signi ficant area controlled by the EPA is the fuel consumption of various types of vehlcles. European Unlon ( EU) Regulatrons are set bythe Europea n Commission (EC). These vary from the North Amerlcan regulations, mainly due to geographic and economie concerns, which lead to greater traffic density. Various European national governments have also set rules to suit the requirements of therr own country. Many of these rules were

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So the overall vehicle size, powertrain layout, occupant package, body archltecture, exterior hghting and interior design are heavily influenced by government legislation and customer advocate groups. Although this subject is very complex, it is worth understanding the basic requirements before developing a package. Lookìng around at vehìcles that are on the road today, you can see there ìs a lot of uniformity. which is due mainly to legislation. As you work through this book. you will notrce that various regulations are mentroned when they are significant to the design. Features like bumpers, lrghts, and pillars are strictly controlled, so if you are desìgning a concept that looks dramatlcally different in these areas, check the appropriate chapter for legislation. On the apposite page is a list of some major impact tests that will shape cars and trucks in the near future. These change with time. usually getting more demandrng.

AOOF CRUSH TEST (I.S Times the Vehicle Weightl

PEOESTRIAN (PROTECTIONIIMPACT TEST

Thls test ensures that the structure will protect the occupants in t he event of a rollover. This test lnfluences the design of the A pillar and windshield header.

These tests help to create a more pedestrlan-friendly front end. A rounded profile and adequate clearance between the outer skin and hard components underneath are requlred to the tests.

LOW SPEED (2.5- Smphl IMPACT TEST

SIOE IMPACT (18mphl POLE TEST

These tests help to create bumper systems that resist damage during lowspeed impacts {under 5mph) and protect adjacent components such as light s, grilles and the hood . The bumper heights are determined by these tests.

This test affects the door packaging and si il design. lt ensures the driver Js protected if the vehicle sl1des into a pale.

(

l \

HIGH SPEEO 140mphl OFFSET IMPACT TEST

SIOE 130mphiiMPACT TEST

The most demanding test, affecting the front end and interior design. lt ensures the driver and engers can walk away from a high-speed impact. Thls test most resembles a typical head-on collision which typically is slightly offset.

This test s1mulates one vehlcle driving into the side of another. lt affects the design of the doors, their apertures and the underbody structure. H-POINT

l 173

MATEAIALS Materia! choice may have a major affect on the package, so the basic properties of each materia! and manufacturing limitations should be understood. As wlth every aspect of advanced concept destgn, traditional practlces and applications should be considered before applying new technology. lf the new ma· terial does not play a part in changing the exterior and Interi or design or create opportunities fora more efficient package. the des1gner may decide not to focus on the materials during the early phase of the project. The type of constructlon methods, however, will usually influence the package. so it ls always lmportant to note how material choice may affect construction or viceversa. Below is a brief overview of some of the common materials used in body construction today. Most car bodies will be a mixture of these, to meet ali of the reqwements placed on them by the customers, manufacturers and legislation.

Steel Steel is an amazlng and versatile materia!, 'lvhich is why it is used so extensively in body construction. lt has many properties which glve it an advantage over other materials.

Alumlnum Aluminum alloy's strength-to-weight ratio is better than steel but often ends up requiring Jarger "box sections" or thicker s. They are also more expensive, so usually only applied when light weight ls a high priority for the product. An aluminum hood assembly, for example, may be about half the weight of a steel equivalent, but will be twice the cost. Although alumtnum ls seen as a softer materia! than steel, it "work hardens" much quicker due to its grain structure, so it is not as formable in a cold state as steel. There are, however, low-production-volume manufacturing processes that require heating the materia l to create the desired forms. Aluminum sections can be extruded with very low investmerit and are often applied to lightweight, low-production-volume body structures, mainly for sports cars where light, stiff structures are desirable. Due to its resistance to electric current it is also more difficult to spot weld, so adhesive and riveted ts are common in aluminum structures. New welding processes and adhesives are facilitating a greater mix of aluminum and steel s in car bodies. Like steel, it will corrode lf not coated but is more resistant to oxidation.

First, it is one of the cheapest materials, and although commodity prices do fluctuate, i: wlll probably remnln mur.h cheapP.r thnn thP. <'!ltP.rnativP.s. lt is Riso idenl for lnexpensive (piece cost), high-volume manufacturlng processes. lt ls very strong and when used In an efficient unibody type of construction it ca n provide a surpnsingly llght solution. High-strength steel alloys ca n al so be utilized if weight takes a higher priority than cost in the product. lt is also very ductlle (formable) allowlng it to be drawn lnto very complex and deep s. Most body side apertures are now stamped in one piece from the "K pillar to the rear of the vehicle, reducing complexity and tolerance issues.

Plastlcs Plastics come in many types with various properties. Some lend themselves to high production volume manufacturing while others are only suitable for smaller production runs. Thermoplastics such as polypropylene are often used when low-speed impact dent resistance is required. This is a popular choice for bumper fascias and door exterior s. These are also very formable so very complex and deep sections can be easily manufactured from these materials. Severa! components can be manufactured in one plastic piece, like the bumper and grill, which reduces assembly complexity and ca n improve design flexibility.

Steel is very easy to spot weld, having a much h1gher resistance to electnc current than aluminum, lts ma in competitor. Steel structures are aIso more durable than aluminum, which can be an advantage in truck frames where thelr flexibility requires resistance to cracking.

Plastics such as SMC (sheet-moulded compounds) or RIM (reaction-injecbon mouldings) are also often used in the manufacture of exterior s that are fastened to space-frame structures.

In the past, a major drawback of using steel was corrosion, but with new coatings and co1struction methods, this ls no longer an lssue. Recycling ls now an lm· portant part of automotive design, and steel's propensity to revert to its originai state, (i.e .. rust or ferrous oxide), makes it even more attractive. lt ca n, of course, also be melted down and reused.

Carbon fìber is only used on specialist applications such as exotic, lightweight sports cars, due to the cost and labor-mtens1ve productton processes. These materials are very light, strong and stiff, resulting in the size reduction or eliminatlon of box sections. They are often used in conjunctlon with other materials to make up a stlff, lightweight body.

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MATERIAL APPLICATION EXAMPLES

SECTIDN THROUGH THE FRONT BUMPER & HOOO

TYPICAL CAR SILL SECTIONS

lllustrating some of the various matcrials used in body and cxtcrior componcnts.

Thesc two sill sections below show how various materlals and manufacturlng processes can be applled to the sa me area of the vehicle, affecting a key area of the package.

HOOD ASSEMBLY - STAMPED ALUMINUM (half the weight of a steel hood, hinged and latched to the steel body structure)

HEADLAMP LENS- POLYCARBONATE (llghtweight, tough, clear, scratch resistant)

BUMPER FOAM · POLYSTYRENE (lightweight, sott, inexpensive)

Stamped steel & spot welded , part of a unibody structure.

FASCIA • POLYPROPYLENE (lightwelght. inexpensive, / damage resistant, formable) _ /

Extruded aluminum slll , part of a space-frame structure.

BUMPER BEAM • EXTRUDED ALUMINUM (lightweight, inexpensive, one piece, stiff)

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l 17S

BODY CLDSURES The closures and their apertures are designed to previde access to the enger compartment. engine bay and cargo area. The various solutions are illustrated below. Their outlines are a design element, so breaking up the exterior s and closures should be considered early in the process.

FRONT HINGEO

FRONT 6 AEAA HINGEO

SCISSOA

This conventional layout is applied to most cars. lt provides independent closures for front and rear engers that are inexpens1ve and simple to operate. lt also requires a B pillar whlch ls essential for an efficient structure. s1de impact and seat belt mount1ng. Longer doors may have four bar-link hinges to help push the front of the door outboard in tight parking situations.

Occas1onally applied to vehicles with a short cab or wheelbase. which reduces the rear-door length. This system ls an lmprovement over a two-door solution. Removlng the B pillar improves rear foot sw1ng and creates a large aperture which may be des1rable for lifestyle vehic es.

This type of door system adds drama to the design of exotlc cars but also has some practlcal advantages. For wide sports cars with dee p si li sectlons, 1t elimmates the problems caused by out-swinging doors in tight parking situations. improving ingress and egress.

UFTGATE IHATCHJ

TAILGATE

LIFT S SWING

The most common rear aperture closure for minivans, hatchbacks and SUVs. Prov1dmg good access from ali angles and cover from rain. Also elim1nates doors from opening into parkmg lot traffic. The backlight glass can also lift independently. Electric operation can help shorter people close the gate on vehicles with a tali roof.

Used extens1vely on pickup trucks, tailgates are designed to remain dropped while the vehicle is In use to extend the bed ftoor. These are usually removable to a id loading of large heavy objects.

Often applied to vehicles that carry the1r spare wheel on the rear gate, making a IIft gate impractical. Sealing the two-piece closure is more complex than a single gate.

176

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H-POINT

GULL WING

SLIOING

ACCESS COVERS

S1mllar appllcation and advantages as the scissor door. This system can only be applled to low vehlcles because it increases the overall height with the doors open, making garage park1ng a problem. The inherent design geometry cuts lnto the roof, lmproving lngress and egress into an inboard seat location. over a tali slll secllon.

Often appl1ed to minivans and commerciai vans. Ideai for situations where an out swinging door ls dangerous or lmpractical. Slìding door systems requlre enough room behind the door to build in a straight. horizontal track wh1ch will carry the door to the fully opened position. These systems can be electrically operated.

For performance or race cars. good access to ali of the powertrain and suspension components 1s important to allow qulck adjustment to thcsc systems. Hlnged or removable covers with s de cut hnes provlde large open apertures.

LIFT G TAILGATE

REAR SWING OOORS

HOOO G TRUNK LIO

This split closure system provides a ftexible loadJng solution allowìng the lift glass to be opened wlthout the cargo spllling out. lt also provides an openlng lo impruve:: po:ose::nget compartment alrflow. The tailgate provides an exterior seating area and extends the load ftoor.

Used mostly on commerciai applications. The double doors are designec to be used 1ndividually or together. They are often designed to open to 180 or 270 degrees to provlde easy access from tne Slde.

For most cars. a stmple hood and trunk lid previde access to the engine bay and rear cargo area. Cut lines should be designed as far outboard as posstble to create w1de apertures. "Ciamshell" hoods have cullines on the side andare more pedestrlan lmpact friendly.

H-POIN

l In

SIDE DDDRS The doors set up the body s1de destgn. They are attached to the body structure by hmges or rollers and latched into position. This separation allows them to be made of different materials from the structure, such as aluminum and plastlcs, creatlng the opportuntty to make them lighter or dent resistant.

FRAMELESS IHARD TOPI

Unframed glass

The three types of door construction shown below are typtcal to most production cars and trucks. Choosing a type of coor system will depend on the various derivattves that are beìng consldered forthe vehicle range-l.e., sedan, coupe, convertible, wagon. etc. Keeping the same door system for every vehicle will reduce investment. Cost. appearance and head ctearance may also affect the choice.

FRAMED

FULL STAMPED

Separate extruded or rolled frames

\ One ptece door outer s

\l Front and rear door outer s

178

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l l ·PDINT

One piece, inner and outer stamped s with the upper frames

BODY SIDE APERTURE DESIGN CRITERIA The door apertures will have a major influence o n the exterior des1gn. Some basic pa-ameters need to be addressed before the design concept moves forward too far. Definitely, door feasibility should be very advanced before the full-size clay mode! is started. The size and shape of the door apertures will be affected by

A PILLAR UPPER Designed to resist roof crush during rollover. lts sectlon has to meet visibllity requirements.

the followmg considerations: 1) A rig•d overall enger celi structure 2) Easy ingress(egress for the engers 3) Good visibllity around the pillars (greenhouse structure)

ROOF RAIL

8 PILLAR UPPER

Helps to add torsional ngid•ty to the body. The seals should be at least 760mm above the H-pomt to :>rovide adequate head-swing clearance.

Helps to the roof during rollover. lt is located behind the driver's eye point. The front seat belts are attached to this structure.

REAR ROOF RAIL Simllar design constraints as at the front door.

A PILLAR LOWER A major component in the front·end structure. lt forms part of the front wheel aperture and is a iso used to mount the front door hinges. The driver's foot should be set up to allow for easy foot swing past the door seals.

Slll _ _ _ _ _ __, Designed to res1st compression during highspeed frontal lmpact. helping to maintaìn the enger-compartment shape. The top of the section is kept as low as posslble to 1mprove the step over.

8 PILLAR LOWER Pushed forwa'd to lmprove rear foot swing, it is an integrai part of the structure for s1de im· pact. Door hinges and latching require room for mountin2 and additional relnforcement.

H-POINl

l 179

CLOSURE PERIMETER "CUT LINES" Closure cut lines referto the external pane! gaps around the hinged or articulating s, like doors, hoods or trunk lids. They can be an important design element and if they are not considered at an early stage of design, they may end up looking untidy or awkward. Thelr location and shape are driven by severa! factors:

INGRESS. EGRESS & ACCESS The main functlon for the closure is to allow people or objects to through an aperture, so this wìll be a primary driver for the cut line location. See side door aperture design on p. 179 for reference.

HINGING. SWING ANO ARTICULATION The hinge axis location and orientatlon or path of the closure assembly (sliding doors) will have a great influence on the shape of the cut lines. For doors that swing, the surface profile swung into the open posit1on is often used to help determine the cut-line shape adjacent to the hinges. Sliding doors travel in t he direction of the tracks and need to have openings that are sympathetic to the door travel path at the start of their motion.

180

l H-POINT

STRUCTURE The body structure will also influence the design of the cut lines. Often the door boundaries will fall inslde the aperture structure as it tracks around the wheel openìngs, sills an d roof rails. In some cases the door's outer surface may averla p the structure to clean up the exterior design or slmplify tolerancing between the doors and body s.

EXTERIOR DESIGN The relative location of the upper-body structure {plllars) and the wheel-house openings will have a dramatic effect on the cut-line shape. The examples on the apposite page show how these elements, in conjunction with the occupant locatton, wlll affect the door perlmeter design. Additionally. the hood. trunk lid and tailgate boundaries may coincide with other elements on the exterior such as glass s, lamps, and grills. Pay particular attention to the corners of the windshield and backlight glass. Their design will affect the adjacent pane! shapes, often inftuencing the closure boundaries. lt is easier to keep t he cut lines tìdy ìf the corners of the glass s are sharp and do not have large radiì.

Example 1

Example 2

The examples above illustrat e how different the side door cut llnes can be on a similar vehicle. Example 1 shows the door perimeters within the structure. This allows the structural box sections to be fully optimized, which is always helpful in small vehicles. The smaller upper door frame ls especially helpful to lmprove head clearance to the roof-rall structure.

Example 2 shows the doors overlapìng t he sills. roof rails and rear wheel house ("dog leg") structure. This solution cleans up t he design and reduces the number of visible elements in slde view. lt also simplifìes the door gap tolerancing and helps to keep t he door apertures clean, which is important in luxury cars and off-road vehlcles.

SIDE DOOR. CUT UNE EXAMPLES

CONVENTIONAL HINGING Setting up the cut llnes adja· ce'1 t to the hrnge axis line is more of a geometry exercise than a desrgn study. Note how the cut Ime rn srde v1ew sympathizes with the end-view. bodysrde surface contour fhe tront edge of the door will swrng '" toward the structure unless the hinges are mounted on the ex· tenor surface.

AEAAWAAO A PILLARS In this example, the A pillar is pulled rearward in relation to the driver to rmprove cornenng vrsibility The front cut lines step forward to improve foot swing.

COMMEACIAL VEHICLES To optimrze the vehicle length, the driver ts often pushed forward in the package. To 1mprove foot swing. the forward cut line will track around the wheel house. This is only possrble wrth a high floor structure. Note the strarght, vertical cut line at the front of the slidrng cargo door. This is not posslble with a conventional swmgrng door.

UNCONVENTIONALHINGING In this example the horizontal hìnge axìs in the roof allows de· sign freedom for the slde cut lines, notably at the front.

FAAMELESS TWO OOORS One small detail to note with this type of door rs that the rear cut line will usually curve rearward JUSt below the belt to provlde room for latch and drop glass packaging.

CAB FOAWAAO Here the A pillar ts pulled forward so the door cut has to depart from the pillar and cut through ìt to fall behind the front wheel-house structure.

EXPOSEO STAUCTUAES Sometrmes the door cut lines will follow the body structure to optimize thc box sectrons and co'Tlmunicate strehgth tn the exterior design.

LAAGE TWO OOOAS large two door cars need long doors to help break up their proportions. The approximate length of the door should be less than 1400mm to reduce stress on lhe hlnges and mini· mize the outward swlng of the door.

•

FOAWARO CONTROL Forward contro! vehrcles are becoming rare in most markets because of frontal impact issues. One thing to consrder on the front door cut ls allowing space for the driver's feet to between the A pillar and front wheelhouse structure. H-POIN-

l 181

FOOT SWING The relationship ofthe driver's foot and thefront tire can be very influential to the package and exterior design. For some vehlcles this relationshlp ls criticai: for others, the two elements are lndependent of each other. The S IX examples at right show various vehicles with signiflcantly different architectures. Note that in each package the relationshlp between the foot and the tire O.D. (outside diameter) is different, and this ls also reflected in the location of the windshield to the front spindle and the overall front-end silhouette.

From a designer's perspective, it is very difficult and time-consuming to get this relationship fully optimlzed on your own. lf your concept calls fora close relationship ofthe foot and t ire in si de view, find an existing vehicle with an efficient package and a similar lateral relationship of the driver and front track, and benchmark it. Ti re turn (turn circle) may need to be considered here, as well as the size of the pillar structure. The A-pillar lower section is the comerstone of the body structure, and along with the driver foot swing, simply cannot be compromised. The lllustratlon below shows how the seat, the door trim and the A-pillar trim need adequate clearance, allowing the drivers to swing their feet through the opening.

seat cushion

A-pillar structure

door fully open

182 l H-POINT

l. EXOTIC SPORTS CAR - FRONT LONGITUOINAL ENGINE RWO

C!. LUXURY SEOAN - FRONT-LONGITUOINAL ENGINE RWO

In thls example there is no relationship between the foot and the ti re. This highperformance, two-enger-car front spindle is set up for optimum weight distributìon, resulting in a long "dash-to-axle" whìch ìs common for most rear-wheel drive cars wìth a longitudinal engine. Here foot swing is seldom an issue.

Thìs rear-wheel-drive car al so has a longitudinal engine but is much shorter and has a much more space efficient package than example 1. Weight distribution is stili a priority but the front wheel is pulled further rearward.

3. EXOTIC SPORTS CAR - MIO-LONGITUOINAL ENGINE RWO

4. ECONOMY CAR - FRONT TRANSVERSE ENGINE FWO

This exotic mid-engine sports car packages the foot forward of the ti re O. D. There are severa l elements in thls architecture that make it possible. The first is a wide track which pushes the tire outboard for greater stability and handling. Next, the driver may be located inboard to reduce the width of the greenhouse, which rcduces drag and the pelar moment. Th s ls the apposite of example 4 where the vehicle is narrow and the driver pushed outboard for interior space efficiency. Lastly, the exotic sports-car owner will be more forgiving of poor ingress and egress if the package improves performance. An unorthodox door opening may also improve the situation.

A typical front-wheel drive vehicle with a transverse engine places a h.gh priority on package efficiency. The driver is pushed as far forward as possible in the wheelbase to create a spacious lnterlor in a very short overalllength. In this type of architecture, it ls very important not to push the driver too close to the tire or it will create an ingressjegress lssuc. Although the moin lssue here appears to be a potenti al clash between the driver or foot pedals and front wheel house. the actual problem is the foot swing past the A-pillar structure, which fs rearward of the wheel opening.

S. COMMERCIAL VAN - FRONT-TRANSVERSE ENGINE FWO

6. COMMEACIAL VAN - FOAWARO CONTROL RWO

This va n has a very tali driver height and pasture. This situation is more forgivlng lhan example 4 because the A-pìllar structure can be moved forward above the step-in area, optlmizing the foot swing. This demonstrates how a tali driver package can help to create a space-efficient architecture ideai for cargo, enger or recreational vans.

This example shows a driver package. These are rare because frontal impact regulations and expeclations have become more demanding. Here the driver requires enough room to between the wheel house and the open door trim as he steps lnto the cab and swings lnto the seat. This ullimately pushes the driver quite a long way forward of the front spindle, leaving the feet vulnerable during a collision. H- POINT l 183

ODOR ANO APERTURE DESIGN The door apertures are developed through about nìne typical body sections. These are cut through the pillars. roof rails and sìll at criticai areas such as the hmge and latch locations. An ·x· section through the H-point rs used to set up the body-side profile through the roof rails. drop glass, door rnner/ outer s and the sill structure. Trrs rs a very rmportant section in the early stages of the package development. Particular attentron is given to the drop glass. Work· ing in conjunction with the side vrew DLOs (daylight openings). the end-vlew sectlon is developed to set up the tumblehome (angle of the glass) along the upper-body srde (greenhouse) and the profile of the door outer pane ls. Door seals are usually mounted aver the weld flanges on the box sections around the apertures, creatrng a clean, soft opening. The openings created by the weld flanges are often referred to as the Pl & P2 curves. The illustratrons an the apposite page show t'ow the drop glass and glass perimeters (daylight openings/ DLOs) are designed to clear the door hardware. Tnis hardware 1ncludes hinges. latches. side intrusion beams and the door inner s. Note how the mirror flag on the front door and the reardoor fixed glass help to reduce the size of the dropping glasses and allow them to track down at an advantageous angle.

SIDE GLASS SURFACING

SECTIONAL VIEW THROUGH THE DRIVER H-PDINT l HEAD CONTOUR Roof Rail Thrs section contains lhe rail structure, door frame, headliner,

''"' •" bag and door .,.,,.

><\

---_..;'(:......_

\

The glass surface must lie on a cylinder or a barrel surface. This allows the dropprng to slide down the run channels and between the belt wrthout bindrng. A twrsting surface lin pian view) or an accelerating surface dn end view) will not drop. The side glass surface is usually the first surface to be set up on the full-size clay model.

- Rari Outer Surface usually about 125mm from the head contour

Cylinder Surface

l

760mm Recommended minimum for head swing clearance

Door aperture open1ng

Barrel Surface

Front Aoor

Step over Frame Rall Section Ground clearance Slll Section A key part of the body structure. (A low si li will improve step over) 184

l H-POINT

r

Rear Door Opening

t--- - - Front Door

Dash 1 Foot well

Opening

Il

Hinge

r

Wheel House

Drop Glass

Drop Glass \

Front Wheel House

l

C Pillar

Latch _ /

Htnge

DoorCutUnes--- -• - - -- - - - - -

Rear quarter

SECTIONAL VIEW A-A

Mirror Flag

Fixed Glass

Late h

-·

_,........ ·"

:/

...-·---· -

·- · A

Drop Glass

r·

\...-·-·-·-·-·-·J

l

Il

A

H·POINT

l IBS

WINOSHIELO APERTURE DESIGN This study shows how typical sections. cut through various elements around the package, are used to set up the wìndshield aperture. Notice that elements of the body structure-i.e., the header and cowljplenum-are shown together w1th the mterior trim ard windshield. The engine and hood are also drawn and the section is completed with the inclusion of the driver manikin to check forward visibility. The exterior shape and location of the top of the windshield is a particularty sensitive design element to the extenor des1gner.

SECTION THROUGH THE WINOSHIELO APERTURES AT THE DRIVER'S CENTERLINE

l

Cowl / Plenum

Hood Assembly

EC FORWARO G SIOE VISION REOUIREMENTS IUP 6 DDWNI Recommended for traffic-light visibility- 14° M1n1mum Up Angle - 7° Minimum Down Angle- 4°

IBS ( H·POINT

,

..

Below is a basic outllne of the pillar obscuration geometry stud1es, lllustrating how the pillar structure and trim are designed to meet specific obscuration parameters. These are usually set up 1n a co-nputer system. Most designers will never have to execute these studies. but need to understand that there are limitations on the size and location of the A pillars. The mam objective for the A-pillar design is to create a strong enough structure to meet roof crush targets but make 1t easy to see around it. A full description of the geometry and eye points (El, E2. E3 & E4) set up can be found in the 77/649/ EC direct1ve and SAE Jl050 recommendation.

17° Min1mum

See 77 /649/EC directive for eye-point set up

6° \1inimum

635

627

H-point

R point

EC A-PILLAA OBSCUAATION

SAE A-PILLAR OBSCURATIDN H-POINT 1187

BACKLIGHT APERTURE DESIGN The regulatiOns affccting rear vis1bility and the backlight aperture are not as stnct as the windsh1eld aperture. Mostly, they require an additional exterior mirror if visibility does not meet the regulations. Ultimately. the design is usually guided by customer req01rements and how com· fortable they are driving with compromised rearward vision. Backup cameras and sensors are providing a greatcr sense of security for cars w1th challeng1ng rear aperture des1gns.

reftected eye point 1

Most cf the requirements or recommendations concern the rearview m1rror. The illustration below shows the requirement to be able to see the road w1thin 60 meters of the rear of t11e vehicle. The sections at the right and bottom illustrate how up, down and s ide to side v1S1on angles are generated from the reflected eye points forward of the mtenor mirror.

l I l

- -- - -- -- ----

-

60m

eye point -1--1--t-1--

-4,

/ i

reflected eye point

IBB

l

H-POINT

i

i

i

i

-

l

i j r--

i i

mterior mirror mounted above vl eye pomt

!/

i

l

i

minimum

..

,.

SECTIONS THROUGH BACKLIGHT APERTURES SEDAN Typically the sedan backlight aperture does not present a problem at the header because it is lifted by the rear headroom requirements. The deck lid however can often be quite high, making rearward vlsibility while backing up a challenge. Benchmark other vehicles in this areato avoid an issue.

COUPE 6 FASTBACK Coupes and fastbacks may have a problem with the rear header height due to the desire for a low roof, which often leads to compromised rear headroom. Notice in the section that the rear header is forward of the occupant's head. This is a common condition, putting the head under the glass. improving head clearance. Visibility over the deck l id may be worse than the sedan because the driver eye pont is often lower to the ground.

HATCHBACK & SUVS Hatchbacks and utility vehicles do not usually have an issue with rear visibility because the roof height is often tali and there is no deck lid. The rear header structure is much larger than the other cars because of the lift gate frame and hinge packaging. Occasionally, on SUVs, the spare tire is mounted on the rear swing gate which may obscure the rear view.

PICKUP TRUCKS Truck rearward vistbility 1s rarely an issue. Most trucks are fitted with large exterior mirrors because the cargo in the bed often obscures the view through the backlight. Here the glass usually slides open for ventllation and bed access.

H-POINT

l 189

TYPICAL SECTIDN DETAIL This Typical Section example illustrates how complex the final body assembly ca n be. Each sectton 1s developed by severa! specialists. In the case of this sill section, structural analysts will determine the cross-sectional areas of the box section, its materia! specifications, thickness and topology. The manufacturing group will determine the s' assembly sequence. flange lengths (for spot welding) and the shape requirements for forming. Other elements that may influence the section design are included in the detail drawings, such as the door, seals, trim components, floor , carpet, insulation and wiring. This ensures that consideration ls always given to t he adjacent components. Additional information may also be added to put the section In context with the package. In this case, ground clearance, step-over requlrements

190

l H-POINT

and s1de-impact test-barrier heights are included. The studio engmeenng group will construct the section initially and work with the design team to create the exterior and interlor profiles. From the designer's perspective, the basic crrteria for each section needs to be understood because this will influence lhe exterior form. In this case, the sill height may be governed by ground clearance , step-over or floor-height reqLirements. The exterior width may be controlled by overall vehicle dimension targets, and the shape of the siil section will vary greatly depending o n the body type and constructlon method. The ma in thing to note here is that every vehicle will incorporate such box sections to manage the stresses and load paths throughout the body structure.

TYPICAL SECTION CUT THROUGH THE SILL AT THE FRONT OOOA

front door trim

scuff plate

/

/ /

l X mm (mlnimum) /

secondary door seal

/

side impact barrier

step over X mm (maximum)

sill claddlng floor wiring bundle

body slde inner (1.5mm steel)

ground clearance X mn (minimum)

1

curb ground line H· POINT

l 191

BASICS OF AERDDYNAMICS Aerody'1amics is a very complex subject and needs a great deal more attention than tris book can previde. However, as with other technical subjects, there are some basic principles that can be applied to help the vehicle meet lts functional objectives. In the case of aerodynamics, each package should be set up to allow the veh1cle to travel through the air as efficiently as posslble. First, look at the importance that aerodynam1cs will play in the type of vehicle you are deg. A sports car with a h1gh top speed, superior handling and coolìng requirements will have a greater emphasis put on airflow and down force. Environmentally-friendly vehicles, looking to reduce fuel consumption. will also need to slip through the air as easily as possible. Trucks, on the other hand, are usually an aerodynamic disaster. with every aspect of their exterior surface work· ing against good aerodynamic principies. Two factors to consider are the drag coefficient (Cd) and the total drag. The drag coefficient ls a factor that deflnes the "sllpperiness" of a particular shape, regardless of its scale. The total drag multiplies this coefficient by the crosssectlonal area (A) of the vehicle to determine its aerodynamic resistance (force) that must be overcome to propel it (CdA). A full-size car and its quarter scale model wlll have the same drag coefficient, but the full-size car will have sixteen times the total drag of the quarter-scale model. From the vehicle-architecture perspective, making the vehlcle smaller In the front view should always be considered lf low aerodynamic drag is a priority. Down force should also be a conslderation. With most vehicles expected to be driven at 70mph or more, keeping more air pressure on top ofthe vehicle than underneath

will help maintain handling characteristics regardless of speed. For high-speed cars it is also criticai that the balance of the car is not affected by speed; spoilers are often applied to help maintain consistent down force on the front and rear tires. Additionally, vehicles need to breathe to perform severa! dlrterent functlons. Engine cooling requires a substantial airflow through the cooling modules or radia· tors. The breathing apertures that allow this airflow are usually very evident in the styling of most cars and trucks. The size of the body opening for the engine is usually about two-thìrds the size of the cooling module {radiator). Openings In lhe front of the carfor brake cooling are a Iso common, with ducting to the brake rotors on high-performance cars. The heating, ventilation & air conditioning (HVAC) system usually takes air in through the "cowl screen" at the basè of the windshield. The outside air enters the car at this low pressure area and travels through the plenum chamber to remove moisture and other large particles. The plenum chamber often serves as part of the body structure and runs across the base of the windshield between the A pillars. Some very high-performance cars may requlre unique ram-air vents to push more air into the engine lnductlon system. Other factors like wind-noise reductlon and water removal are high considerations in luxury cars, but these are often addressed with localized surface contours and hardware details. which will not affect the package. The two illustrations apposite show some of the fundamenta l dos and don'ts of packaging to create good aerodynamics.

engine air induction cowljplenum · cabin fresh air intake

BREATHING APERTURES These can be major exterior design elements in exotic sports cars

engine and rear brake cooling

192

l

H· PDINT

EFFICIENT DESIGN

aerodynamicly friendly roof profile

raked windshield

sharp deck cut-off

small streamlined mlrror low raked front end

front air da m rear wheel-house faring tight wheel to body

low ground clearance

small vents In wheel covers

smooth underbody

Being small, low and narrow, the car above has already reduced drag. Additionally, the low front. gently contoured roof line. sides tapered in toward the rear, a s1arp rear cut-off creating minima! turbulence, and fared·ln rear wheels further contribute to low drag.

large flat mirror

INEFFICIENT DESIGN

deep side glass offset

sharp front header

rounded rear header

upright windshield large cab/bed step

large wheel arch openings

open bed

tali upright f ront end rough, deep grill contours

high ground clearance Jarge openings between wheel spokes This is an ae•odynamic nightmare. With the Jarge, high and wide body, the vehicle above Will have to push a lot of air out of the way as it travels at speed. The other features on the body will disrupt the airflow, creating additional drag, particularly the abrupt changes of body shape and untidy underside. H-POINT

l 193

LIGHTING BASICS The lights are an important safety feature, so tl"e1r des1gn is stnctly controlled by legislation in ali markets. This aspect of vehicle design ca n be qui te complicated. so it is adv1sable to get a good basic understanding of the purpose and tunction of each light first, then learn the spec1flc details later. Each llght serves a speclflc runctlon, either to Illuminate Lhe road al n1ghl. to make the vehicle visible in the dark or bad weather. or to communicate to other drivers what the vehicle JS about to do: stop. turn or back up The size and location of each light will depend on illumination targets or specific surface-area requirements set out in the legislations of different parts of the world. European lighting tegislatJon differs, for instance, from US requirements. The headlights are designed to various tests and their s1ze will depend on the technology applied, whereas most of the other lights and reflectors need to meet m101mum lens surface-area and visibllity requirements.

TYPICAL SECTION THROUGH A MULTI-CAVITY REAR-LAMP ASSEMBLY Note the depth of the lamp cavities. These will intrude into t11e trunk space and may be a challenge to package if mounted on the rear pillars.

\ talltamp

Each lamp ls made from t11ree components: the buib, reflector and tens. Some assemblles occupy large volumes and need to be cons1dered early in the package process. Additionally. because they are a safety rtem. they need to be protected and their relationship to the bumper systems is an mportant element in tne exterlor design. Widespread adoption of light-emitlìng diode (LED) technology 1s changing t he approach to the engineering design of lamps. This is giving designers new OJ:> portun1ties for the shape and appearance of lighting. aithough the posit1o01ng of the lamps remains regulated.

back-up l fog

l 194

l

....

TYPICAL SECTION THROUGH A GENERIC HEAOLIGHT ASSEMBLY hood or fender assembly

lens (usually made from polycarbonate)

headlight mounting

'l

bulb assembly

Size and shape of the aperture may be driven by the exterior design but the mìnimum slze will have to previde enough light to meet legai requirements.

wheel-house liner

'

-

bumper offset reflector (usually a parabolic curve)

bumper outer

bumper beam

foam

H·POINT

l 195

EXTERIOR LIGHTING REQUIREMENTS

g

,-

•

HEAOLIGHTS

FRONT FOG

GENERAL · Consisting of a high and low beam to illuminate the environment in front of the vehicle. · Lens minimum sizes are determined by photometric requirements and lamp technology.

GENERAL Two forward-facing lights mounted symmetrically about centerline. Fog-light function is separate from headlight.

US REQUIREMENTS (FMVSS108) · Two or four lamps set symmetrically about centerline as far apart as practical. ·High bea m must be produced by inboard or lower lamps · Center of lamp height from ground 585*min-1346max · Approximate reflector diameter to meet photometric requirements: 140 low beam, ilO high beam (projector lamps, 60 LB & 70 HB)

f)-,

EUROPEAN REQUIREMENTS (EC - European Commission) • Bottom-lit edge of low-beam height from ground 500mln-1200rnax · Outer-lit edge to widest point of vehicle, 400rnax · Low beam to be visible 10° inboard. 45° outboard. 15° up and l0°down

PARK ANO TURN GENERAL Park - lndicates the vehicle's position when parked or during headlight failure. Turn - Flashes to indicate the driver's lntent to turn, and can be used together for hazard warning. Mounted symmetrically about centerline. US REQUIREMENTS • Minimum separation between bulb centers, 635mm · Height from ground 406min-1803max (park) & 2083max (turn) · Approximate reflector diameter -70 to meet photometric requirements EUROPEAN REQUIREMENTS ( EC)

· Bottom-lit edge height from ground 500min-1200max • Outer-lit edge to widest po:nt of vehicle, 400rnax · Low beam to be visìble 10" inboard, 45° outboard, 5° up and 10° down 196

l

H-POINT

US REQUIREMENTS (SAE - Soclety of Automotive Engineers) · Bulb center from ground, 304min-763max · The lit edges of the two lights should be 508mln apart (IIHS - lnsurance lnstitute for Highway Safety) · Recommended setback from fascia surface, 25m in EUROPEAN REQUIREMENTS (EC) · Edge of reflector to ground. 250m in- 800max · Edge of reflector to outboard edge o t vehlcle, 400max

Side markers indicate the overall length of the vehicle (not permitted in Europe)

US REQUIREMENTS · Minì1nun 1window 13x20 1nu:>llJt! visii.Jie ol47° forwarcJ and rearward of the bulb, 12° up and down · Height from ground, 406min · Located as far forward as possible · Colors: front- am ber, rear- red

SIOE REPEATER LAMPS GENERAL Work with turn signals to show intent to turn or change lanes to vehicles travellng alongside. (not required in US) EUROPEAN REQUIREMENTS (EC) • Bulb center height from ground, 525min-1475max · Distance from front of vehicle, 1800max · Must be visible from between 5°-65° from Y piane at the bulb center *Ali measurements in mlllimeters unless otherwise noted.

CENTEA HIGH-MOUNTEO STOP LIGHT ICHMSLI

TAIL STOP. PARK G TUAN-SIGNAL LIGHTS

GENERAL · One red light mounted on the vehicle centerline facing rearward, actlvated with brake hghts. · Not permitted in Europe

GENERAL Taìlltghts- (Red) Mark the presence of a vehtcle and work with the headlights or park. Brake lights - (Red Indicate the vehicle is slowìng down/ stopptng. Tum Sagnal - (US: red or amber. Europe: amber) Flash to indicate driver's tntent to turn. or for hazard waming. · Ali mounted symmetrically about centerline and must be fixed to the body, not closures.

US INFORMATION · llluminated lens at least 29cm2 ·No part of the lens to be more than 76mm from the bottom edge of glass (152m m below the rear window on convert· ibles.) · Should be visible from 47• either stde of centerline. 12• up and JD down. (lens vìsible surface to be at least 6.25cm2 when viewed at 4 5°).

BACK-UP LIGHTS GENERAL · For lllumination behind the vehicle, and they previde a warnìng signal when in reverse. · Only one required, two optional (must be symmetrical) · Whìte in color US INFORMATION · Must be visible to a pedestrian eye point which is 1S30mm above the ground & 915mm behind the vehtcle. · Must be vtstble 4 r either side of the bulb. EUROPEAN INFORMATION · Hetght from ground to llumtnated area, 275min-1175max

AEAA FOG LIGHTS GENERAL · Red tn color - For making the vehicle more visible tn fog · Only one requìred. mounted on centerline or dnver's sìde · Two optional (must be symmetncal) · Not permttted tn USA EUROPEAN REQUIREMENTS • Heignt from ground to illuminated area 275mln-975max · Separatlon to stop lamp (a.k.a. brake light), 100m in

US REQUIREMENTS · May be combined into a single llght ·Located at the rear of the vehicle, within the outer 25% of the vehicle width · Height from ground, 406mtn-1S03max (turn stgnals. 20Smax) · lliuminated area of the brake light or tali/stop to be at least 50cm2. For multiple compartment lamps each lens must be at least 22cm2 with a total of at least 50cm2. Vehicles over 2030 wtde, must have at least 75cm2. · The lens must be visibie at 4 7• either Stde and unobstructed 12• up and down. The tllumìnated area of 13cm2 at 45° ·Separate turn signals should be vistble a t 4 7° outboard-22° tnboard. EUROPEAN REQUIREMENTS · Tail and tu m to be located at the rear of the vehicle. wtthin 400 of the edge of the outer edge. · The tu m signal shOuld be the furthest outboard lf clustered horizontally • lnboard lit edges should be posationed at least 600mm apart · Height from ground, 375min-1475max (rear reflex S75max) · Must be visible from: Tail - so• outboard, 45° fnboard Stop- 45• outboard, 45° fnboard Turn- so• outboard, 45° lnboard an d unobstructed 15° up an d 5° down · Minimum illumtnated lens area of 13cm2 at extremes of vistbility angles · Brake and fog lights must have a separatton of 100min · Tail and fog ca n be combmed

H· POIIH

l 197

BUMPER DESIGN (FOR LOW-SPEED IMPACT TESTINGI The US and Canadian govemments both require enger car (trucks are exempt) bumpers to meet low-speed impact tests. The tests range from speeds of 2.5mph to 5mph and alm to minimize damage caused in minor accidents. The reqwements dlffer s11ghtly for each country, but essentrally cali for the front and rear bumper systems to protect the adjacent areas frorn damage, especrally the safety rtems such as lights. The car is hlt by a steel "pendulum· at 405mm and 508mm abovc the ground. Thrs is applied at centerhne and at the comers. To the tests

the bumper profile is offset from the surroundrng surfaces. To set up the bumper offsets, benchmark existing cars to get the ideai or mrnrmum condition. Offsets will vary dependrng on the vehicte weight and the cost of the bumper system, so always compare srmllar types of cars. Getting the bumper offsets to took good and meet the impact tests ls usually a challenge to a design team.

TYPICAL GENERIC SECTION THROUGH A FRONT ENGER CAR BUMPER SYSTEM

r·-·-·,

t

pendulum test device

bumper offset -

- adjacent components. fender, hood, etc.)

Il

l

jT_,

buMper band

508mm

bumper 1 fascia outer (usually made from polypropytene}

_l

405mm

.

.l L . ..J

buMper band -

'

ground 198

l H-POINT

GROUNO CLEARANCE The relationship of the body and underbody components to the ground should be appropriate to the use of the \iehicle. Road-going enger cars are set up to be driven without to the ground when fully loaded. Off-road 11eh1cles w1ll need to be ra1sed according to their intended capability, which may also include

being driven through water. Some sports cars can be desìgned with compromised ground clearance to improve aerodynamics. but the owners will need to accept the lìm1tations of their vehicle in some situations.

ground clearance to underbody - 205mm \ departure angle- 20•

OFF-ROAD VEH ICLES

The mlnimum ground clearance dimensions shown are set by various governments to determine that the vehlcle ls suitable for off-road use.

curb ground line

ground clearance to underbody - 160mm

ramp over angle - 12° departure angle 16"

ENGER CARS

PAAKING BLOCK

These angles are qui te low an d are examples taken from typical products at curb attitude. Some specialty sports cars may be lower.

D,_____

curb ground line

full-rated ground llne Note: See the SAE J689 for ground-clearance recommendatlons. These are measured with the vehicle at compressed suspension attitudes. H·POINT

l 199

GLAZING The ma in objectNes for the gtass s are to protect the occupants and allow them to see out. In many cases. they a Iso articulate to provide ventilation or access.

The sectton below shows how a typical glass aperture is configured. Each aperture 1s surrounded by a box sect1on. and the glass 1s mounted on the spot weld flange, tn a rebate and held in piace with adhesive or rubber molding. A blackout, or tnt. 1s pamted around the perimeter to hide the adhes1ve and mterior trim.

Glass is one of the oldest materiars used m \ehicle design and is st11l manufactured using traditional processes. which can fimit the design of each . The ma1n reason il is stili used extensively is because of its opttcal qualtttes and hardness (scratch resistance). unlike some ptastics. This makes il tdeal for applications where 1t s other abrasive components, such as wmdshteld wipers and belt moldings.

The ma1n thmg to note here 1s tlle d1stance between the edge of g1ass on the extenor surface and the "daylight opening· (DLO) on the frit. Because of this, lhe section has to be designed before accurate vis1on studies can be completed and the edge of glass set up.

Two types of glass are used. lamtnated (for windshields) and toughened (for side glass and backhghts). The lamtnated glass is thicker, usually 5-6mm, and is therefore quite heavy but will not shatter when struck. unlike t he tempered glass which is usually about 3mm th1ck and designed to shatter into small pieces on 1mpact.

TYPICAL SECTION THROUGH A WINOSHI ELO HEAOER

roof outer pane l

edge of glass butal rubber adhesive - head impact foam

lammated glass windshield

--------;r

windshield header s headhner trim forward ·up angle" vision fine aperture spot weld fnt (blackout)

\

200

l H-POINT

daylight openmg curve (DLO)

WINDSHIELD The main objective for the wirdsh1eld is to get the optics as clear and free from distortion as possible. The more aggressive the lnstallation angle. lhe grealer ll1e po1ential is for distortlon. Most exotic sports-car glass is quite flat to counter this.

SIDE GLASS IDRDPPINGI

SIDE GLASS IFIXEDI

The surface contour IS engineered t o drop lnto the door through the belt molding. See pages 184-185 for more

Slmllar to the droppingglass, but1ts shape 1s nol restricted by the dropping function. These may plvot aut far ventilatlon or be bondcd to thc body.

Side-view curvature ìs usually kept to a minimum, but plan·view curvature is common, especially on vehi· cles with more upright wlndshields.

BACKLIGHT This glass does not have optical or mechanical criteria to restrict 1ts shape and is only lìmited by its manufacturlng process. Heatlng clements are usually applied to the backllght glass . These are often h1nged. frameless freestanding panPI!';

WINDSHIELD INSTALLATIDN ANGLE Greater than 60° ìs cons1dered an aggressive angle.

H-POI

l 201

LICENSE PLATE MOUNTING

FRONT

AEAA

L1cense plates are mandatory for ali road veh1cles in every market. Theìr sìze, locatìon and illumina· tion are governed by legislation. They are often an afterthought to the vehicle design, but due to the1r sìze ard positional requirements should not be overlooked for too long.

Front lìcense plates are opt1onal in some regions of the USA but required m most markets so are usually included in production packages. These are often located in front of the bumper beam or below, in the front spoiler. One main issue to conSider ts engme coohng. Tne oreatnmg apertures for cooling are normally designed above and below the bumper beam so placmg the lioense pia te over the location. bumper beam is often a

Rear hoense plates require illuminatton and are usually placed in a pocket to make this poss1ble. The locat1on. size. depth and angle of the pocket ca n val') a great deal dependmg on the market and styling requirements. The plate is allowed to be htted w1th tne rear closure (trunk lid, tailgate etc.) and is often mounted above the rear bumper on the lift gate or trunk hd. The d1agrams on the oppos1te page Illustrate the requirements and posslble solut1ons for license plate accommodation.

202

l

H-POINT

-.

.LICENSE PLATE SIZE 6 LDCATIONS

Max. angle from vertical, 30° up 15° down

license plate size

r

Europe

1.20 mm

'

-

IECI

-

520mm

sìde vìew

Max. Height 1175 mm Min. He1ght 325 mm

front

rear

'

sedan rear- bumper mounted

llcense pldlt: :sw::

The front llcense plates should not block airflow to the engine-coolmg apertures. Veh1cles sold in gtobal markets will have a llcense pocket to accommodate the largest plates in alt dimensions or make separate s for each market. European plates a·e the w1dest (520mm), and US plates are the tallest (152mm), so a mìnimum pocket size of 520mm x 152mm will work in ali markets.

Max. angle rrom vertical 13.5"

\

USA l Canada

152mm

sedan rear trunk lid mounted

'

side view -

305mm

Trucks with removable tailgates should locate the license plate on the bumper.

u front

rear

l

'

Max. Height 1220 mm Min. Height 305mm

'

pickup truck rear H-POINT

l 203

INTROOUCTION TD MDBILITY Il ls qu1te certain that the automotive industry will undergo major changes in the com1ng years due to many factors. Not least among them wì1l be the need to prov1de ever more sustainable transportation ard personal mobtlity, particularly in our urban envlronments. Il ls In everyone's lnterests to encourage designers to be thinking hard about what these Innovative transportation solutlons could be, so Lhal whatever they are, they are compelllng, convenient and really coot to use. Ali of the information 1n th1s book can be equally apphed to these new kinds of transportation dev1ces. So when you find yourselves being asked to design unusual or groundbreaking new types of vehicles, you can stili approach the arch1tectural ìdeation in the ways that we suggest. even if the functìonal objectives and mechan1cal components might be very different from a regutar car or truck. R>r example, there is a compelling argument to be made for smgle seat, urban commuter vehicles for the 80% of drivers who typìcally travel alone to and from work. Such veh1cles could be extremely energy-efficient and take up very llttle space to park. However they would stili need to be safe mixed in wlth regular traffic and they need to be fun. comfortable and convenient to use to cncourage as many people as possible to use them. How would you go about figuring out the architecture? Would they be tali and narrow or low and wide? How would people get 1n and out ofthem? How much protection would people expect and how much structu•e would actuatly be needed to give that protectìon?

lf designers are totally comfortable with usmg the packaging tools in this book for familiar kinds of road veh1cles, they can make a huge contnbut1on to lnnovation within the industry with excitmg new kinds of transportation that people really want. l he ablllty to successfully package a complete car or truck is really about un derstanding a vehicle as a system; seeing the complete product as a complex arrangement of mterrelated subsystems. Car deslgners, 1ndeed designers in ali disciplines, will mcreasingly hear the term "systems th1nking: As the wo•ld w1th1n wh1ch we live becomes more 1nterconnected and more complex. profes· sional car des1gners ca n no tonger th1nk just about the specific product that they are workmg on. They are increasingly required to understand the context within which their vehicle is going to operate, whether that relates to the need to reduce emisslons, use less oil-based fuel, be manufactured for total disassembty at the end of 1ts lite orto be sol d in a market that taxes footprint or weight. They have to become systems designers as much as product designers. When car designers take this understandlng of systems thinklng to the next scale, and combine lt with their instinctive skills and ion for creating great-looking cars, they w111 find themsetves better equlpped than anyone else to propose exclting alternative solutions to personal mobil1ty and transportation. ThP. illustration below outlines some of the modes of transportat1on that could work m combination to provide exc•ting opportunities for futuristlc transporta· t1on systems. For each mode-Segv.ays. bicycles, motorcycles, electric sco:>t·

206

l

H·PDINT

ers. neighborhood electric veh1cles. the list is endless-there is an opportunity far designers to create excitmg·looking products that fit into a total system and are hugely fun to use. The truth IS that most transportation devices that are not cars or trucks do not get deslgned in automotive studios-and they look like 1tl Car designers have abundant possibilities to apply their skllls and ions to ali these other kinds of transportatlon products as well as to cars.

The scenano below looks at a 2030 1nfrastructure solut1on. The foundatiOn of th1s concept is the ·sunshine economy· focused on the sun as a source of infinite power and an ideai living environment. Naturally, this concept is based m the deserting the two c1tles of Los Angeles and Las Vegas. The 270 mile stretch of rail line ls a solar collector not only feeding the hlgh-speed mass translt system, but al so the c1t1es that are developed along lts route Feedlng on many peoples desire to live in ldylllc resort communities which are connected to large cities for commerce and culture, the high-speed rail l1nk travehng at 250mph allows this new soc1ety to have the best of both worlds.

Thinking about advanced mob1lity systems is fascinating. lt involves thmking about human needs 10 a hollst1c way, and then remventmg urban and suburban landscapes without the baggage of past eras. These total solutiOns reqwe an understanding of not only the vehicle designers· knowledge. but the skills and w sdom of others too: urban planners. mf'astructure engineers, energy experts, government policy makers to name just a few. Transportation designers need te be right in the middle of ali this, thinking and using the1r ions to inspire everyone else mvolved.

Looking at the personal mob1l ty vehicles for this scenario reqwes a new perspective and a fresh set of funct•onal objectives. Each car wil on y need to travel short distances between stations and outlying districts. Government subsidies will encourage battery-energy storage to completely ehm1rate a1r pollutiOn and oil dependency. The cargo bays on the tram w111 lim1t the tootpnnt of each vehlcle to provide optimized carrylng capacity. Communication and entortalnment will change the way the lnteriors are designed.

Of course, we often have to walk backwards into the future, settling for compromises forced on us by the redundant elements in our environment. The Industriai Revolution has been an enormous science experiment from which have grown some massive cities. Many of these cit1es are beginning to contract and decay as lhe world moves into a new era. driven by an tncreased understanding of the need for susta1nability and ed by advancec1 technologies. communlcatlons and constantly changing politica! will. Centralized manufacturing and employment. as well as inefficient use of rapidly depleting oil reserves, belong to our past.

..

The possibllities are endless. constrained only by our imaginatlon and the will to live in a perfect world created by 1ntelligent choices.

.

H-POIN

l 207

a - PACKAGE IDEATIDN

Exercise l - SETIING FUNCTIONAL DBJECTIVES

Exercise

Set aut some clear functional objectives for the three entities: customers, brand and market environment.

Loosely sketch some basic package concepts based on t he functional objectives whìch drive the architecture. Each sketch should only take a few minutes. Don't worry too much about scale and keep sketchlng untll you have exhausted ali the possibilities.

CUSTOMERS: - Purpose of the vehicle - Number of occupants - Type of occupants (gender, age, nationality, phy<sical disabilities, etc.) - Performance and capabillty expectations (acceleration, top speed, handling, off-road capability, GVW, towing capacity) - Purchase cast & cost of ownership (economica!, luxurious, exotic, practical) - lmage (modern, retro, prestigious, ecologica!, safe, bold, high-performance) MANUFACTURER l BRANO: - Vehicle position in the brand portfolio - lnvestment & manufacturing costs - Annua l sales volumes (1-100; 100-5,000; 5000-50,000; 50,000-100,000;

100,000-1,000,000) - Marketing strategy (traditional dealerships, Internet, loss leader, ha lo, concept) - Technology (traditional. advanced)

MARKET l ENVIRONMENT: - lnfrastructure, terra1n & cl1mate size, engine sìze & output) - Size limitations (length, width, height, - Legislation (safety. emissions, fuel consumption, lighting) - Crashworthiness (front & side impact. rollover, low-speed impact) - Consumer advocate groups (JD Power, MSN Autos, EuroNCAP, lnsurance lnstitute far Highway Safety, Consumer Reports)

210

J

H-POINT

Focus on the following elements: - The occupant package -Cargo - Powertrain & Fuel Storage - Wheels & Tires - Special features (doors, flexib le seating, aerodynamics, alternative body con· struction, convertible top, etc.) Sketch each package concept in at least two orthographlc views and add isometric illustratlons where necessary. Continually rev1sit the funct1onal objectives to make sure that they are feed1ng your ideation. Work out which systems are important to the success of the concept and begin to establish a hierarchy. Determine which elements are subordinate and which ones lead.

... Exercise 3 - SIZE ANO PRDPORTIDN l BENCHMARKING

Exercise 4 - OCCUPANT PACKAGING

Choose a direction from the package ideation sketches and establish the size and proportion of that concept. Look again at the functional objectives to see which key dimenstons deserve the most focus. Use known benchmark products to help build the package in chunks, using a separate product for each chunk if required.

Set up the occupant package based on the functional objectives and benchmark studtes. Accurately positton the SAE 95th percenttle male driver in front and rear views. Include ali of the theoretical construction lines and datums. including the H-point. Heel point, bali of foot. shin and thigh centerltnes. back angle, effective headroom (8 degree) li ne. headform and eye ellipse wtth vtsion angle lines. Next locate the rear engers also usìng the 95th percentile manikins

Set up comparlsons for: 1) Occupant package and interior environment. Look at occupant locatìon and pasture. Also focus on the space around the manikins. 2} Cargo. Think about volume, size and weight of the items to be transported, and set up space around the occupant package. 3) Powertratn package. Choose a product with a similar propulsion system and note the spacial envelopes around the ma,or components. 4) Ground clearance. Look at vehtcles with similar capabtlttìes (off·road vs. on· road) to your concept. and note the relationship of the underbody components to the ground. 5) Crashworthiness. Study vehicles that meet the appropriate safety standards and note the "crush space" and structure allocated to protect the occupants. 6) Wheel and Tire package. Compare the tire outside diameter and profile to vehicles of stmtlar size and capabllity. 7) Other Elements. Study other sigmficant components tn the concept, such as windshield placement. closure arttculation and cut lines, lightmg, and seatmg f1 exibiltty.

To help set up the occupants priorltlze the followlng: Aerodynamics and Handling • Comfort and space • lngress jEgress • Safety & Security • Package Efficìency • Ground Clearance • Durability • Load Carrying

Establlsh some key target dlmenslons for each row of occupants H·POINT HEIGHT FROM GROUNO CHAIR HEIGHT (H·Pt. to Heel) BACK ANGLE FORWARD VISION ANGLES EFFECTIVE HEAOROOM

Establlsh some key target dimenslons: SHOULDER ROOM LENGTH LATERAL LOCATION W lOTH

COUPLES (lf applicable) HEIGHT WHEELBASE TIRE 0 .0 . GROUND CLEARANCE

H-POINT l 211

Exercise S - INTERIOR ANO CARGO

Exercise 6 - POWERTRAIN PACKAGING

Set up the interior environment around the occupants. Look at each major componenVsystem and establish its relationship t o the occupants.

Select and lay out the propulsion system. Look carefully at the functional objectives and benchmark studies to understand the concept's performance reqwements. wh1ch 1nclude top speed, acceleration, weight, fuel consumption, emissions and traction requirement s. lf a trad1t1onal internal-combustion-type system is chosen, th1s process should be quite straightforward, by benchmarking exlsting products. Specifying a less conventiondi, electric or hybrid powertraln will be a more complex process and involves calculations to establish a power-to-weìght (and vehicle efficiency} ratio vs. speed and range.

Focus on the following: Headllner and door t rim (use these t o set up the exterior hardpoints} Corgo storogc orcos - Steenng wheel, controls and lnstrument pane! Telematics · Seat1ng systems · Aoor consoles To help set up the storage areas, llst t he items to be carried and note the size and welght where appropriate.

Set out the priorities for the powertraln. Organlze the following in order of prlorlty. Power and image • Handling and Aerodynamics • Off-road ca'pabihty • Cast Fuel Consumption and Environment • Package efficiency and occupants

Examples: llst Target Speclflcations for the followlng: Purse • Celi Phone • Briefcase • Grocerles • Dry Cleaning • Weekend Luggage • Famlly Vacatlon Luggage • Dog • Tools • Bikes • Skis/Snowboard • Strollers • Buildlng/Landscaping Materials • Golf Clubs l o help allocate additlonal space and provlde other attrlbutes, also note lnt erlor functions that may requlre speclal consideration.

Top Speed Acceleration 0-60mph Fuel Consumption (MPG or equlvalent) Emission Requìrements (ì.e., Zero) Specify the type of system and the components:

Examples: - Type (internai combustion, eiectric. rybrid or other) Outside vislblllty • Reclmed Sleep1ng • Video screen vis1bihty • Face-to-Face seatlng • Tables and Work surtaces • Cookmg • WorkjBuslness Meetlngs Automated Driving • lnterior Flexibllity (i.e., stowing seats)

- Fuel type (Gasoline, Diesel, Hydrogen, Bfofuel, Electric, etc.) - Motor: Size (cubie capacity) Configuration {V8, Flat 4, stra1ght 6, etc.) Locat1on Orientation Power output. BHP or kW Torque

212

l

H·POINT

Exercise 7 - WHEELS ANO TIRES

Exercise 8 - SUSPENSION ANO CHASSIS

Establish the wheel and ti re slzes for your project and position them in the package. Start by setting an approximate target tire diameter and proflle wldth. Al so state the desired wheel size. Locate the sp1ndle centers and establlsh the track width.

Select a front and rear suspenslon system tor your concept. Look at the functional objectives and prioritize the following:

On-road handling • Off-road capablllty • High GVW • Package efficiency • Rtde Check the functlonal objectlves to establish the prlorltles for this task. Organlze the followlng nl ne factors In order of prlorlty:

comfort • Exterior Design • Cost Based on the prlorlties, choose the appropriate syst ems and descrlbe the following:

On-road handling • Off-road capability • High GVW • Package efficiency • Ride comfort • Appearance/lmage • Adverse weather • Brake packaging • Rolling resistance

-FRONT - System name or mechanism and Spring type

Llst the followlng speclflcatlons for the Front and Rear Wheels and Tires:

- REAR - System name or mechanism and Spring type

- Technology and Tire type (conventional, run flat, off-road, vanable inftation, etc) - Tire-size specifìcatlon (i.e., P 225 1 45 R 17) - Tire O. D. - Wheel rim width

- Suspension travel dimenston front an d rear (curb attitude to full jounce)

enger car, truck,

- Steering System - Braklng System

Also conflrm: - Wheelbase - Track - Turn Circle

H-POINT

l 213

Exercise 9 - BODY ANO EXTEAIDR FEATUAES

Exercise IO - CREATE A PACKAGE LDGIC DRAWING

Determine the body style for your concept and choose a type of construction. Thìnk aoout the followmg before making these decisions:

Compila the information gathered m the previous nine exercises and clearly communicate the package with a clean and graphically appealing drawmg wh eh should be created m Adobe lllustrator or a s1mìlar computer graphic system. Reference the layout on pages 216-217.

The veh1c1e·s purpose and funct1on, annual sales volumes. we1ght targets. cost. investment. paint, durability, towing capacity. closures, load-carrying capacity.

Include the following lnformatlon: State the followlng:

- Functional objectives for the concept and a brief description of the vehicle - Body style (sedan, hatchback. min1van. pickup truck, coupe, convertible, etc.) - Target Specificat1ons - Number and type of doors (sliding, gull wing, rear-hinged, etc.) - Other sign1flcant closures (tail gate, hatchback) • Estimated Annua! Sales volumes (custom, low, medlum, high)

• Orthograph1c side and end views showing the veh1cle outlmes and the basic layout of ali of the systems. (Adda pian view if requ1red to ciarlfy the story). • Benchmark comparisons that illustrate the overall proportions, the occupant package, powertram layout and any other significant features.

- Type of construction (unibody, body on frame, space frame) • The key exterior and interior dimensions Materials for the structure, exterlor s and closures - A basic description of each system • Special glazing requirements (tali belt height. extreme wmdsh1eld angle. dropping side glass. etc.) - Consider the size and locat1on for the other exterior features (lights, breathing apertures and license-plate pockets)

214

l

·POINT

The s1ze, scale and layout of the drawing should be determ1ned by its use (with other design work) as part of a studio presentation, but should also work in a portfolio. This may require it to be set up on severa! sheets and printed out at various scales to suit each specific purpose.

RESOURCES H-POINT only scratches the surface of automotive design. The rest of the vehicle creatlon process is very complex, so use ali of the resources avallable to you onllne or in book form. At the end of the initial stage of the project go back and check your work. Now that the design possibilities have been narrowed down it is more effective to look deeper into each aspect of the vehicle architecture. Try to cross-reference two or more sources to validate your information.

Below is a list of resources you may want to use to gather information. Generai vehlcle design guidlines and practices Society of Automotive Engineers ............. ....... .......................... Generai lnformatlon on current products Manufacturers· websites, i.e. .................................................

www.sae.org

www.audi.com

Customer advocate websites ... ... ... . ... . .. .... ... . .. .. .. ... . . .. .. . .. . www.jdpowers.com Consumer information .. . .. .. .. . ....... .. .. .. .. .. .. ... . .... . ......... .. . www.autos.msn.com Encyclopedic information .......................................... ........ www.wikipedia.org Materlals Steel .. . .... ... .. •...... ... .. . ... .... .. ... ... .. . .. .... .......... ..... ...... ... ..... www.autosteel.org Aluminum ................................................................ www.autoaluminum.org Plastics . .. .. .. .... .. .. ... . .. .. ........ .... ..... .... .. .. .. . .. ... .. .. . ... . ... .. www.plastics-car.com Vehicle Package Reference Data & lnformation Road & Track Magazine (Data s) ...................... .. www.roadandtrack.com Autograph Dimensions GmbH ..... ... .. .... .. ......... .. ... .. . .. ..... ... www.autograph.de Safety & Crashworthiness US Government Organization ..... ........ .......... ... .... ..•. ......... www.nhtsa.dot.gov lndependant safety assessment .... . ..... ..... . ..... ....... ...... www.safecarguide.com Europe .. .... . ... .. .. . .. ... .. . .. .. ... . . ... .. .. ...... .... .. .... ..... .. ............ www.euroncap.com USA .......... ... . .. .. .. ... .. . .. .. .. .. .... .. . .. . . ... .. . .. .. ... . .. .. .. ... . .. .. .. .. .. . ... www.safecar.gov The lnsurance lnsitute for Highway Safety ................................... www.iihs.org

Vehlcle Systems Many vehicle systems are manufactured by suppliers. Try to build a database of suppliers for each type of system or process. Here are a few. Ali systems ....................................................................... www.magna.com Interior systems ............ .... . .. ... ..... ...... ...... ............ www.johnsoncontrols.com Powertrains ... ... .. ... .. ... ... . ...... ... ... .. .... . .. ... .. .. . . ........ ... ... ....... www.ricardo.com Fu el Cells •.. ... .......... ......... ...... .......... ........ ......... ...... ........ .. www.ballard.com Electric Motors . ... .... . .. ... ....... ... ..... .... .. . ... . .... . .... ..... ... .. ....... ... . www.uqm.com Batteries ... .. .. ... ....... ............. ........ .... .... ...... ... .......... www.a123systems.com Manufacturing .. .. .. ... . . ... .. . .. .. ... ... .... ... . .. ........ .. www.automation.siemens.com Ergonomics ...................................................... www.mreed.umtri.umich.edu Wheels an d nres (Tire & Rim Association) ...... ... .... .. .... .. ......... www.us-tra.org Vehicle Design & Engineering Books Fundamentals of Vehicle Dynamics ..................... .... .. . by Thomas D. Gillespie An lntroduction to Modern Vehicle Design ........ by Julian Happian Smi1h (SAE) Automotive Ergonomics . ....... ... ... .. .. .. ... ... ..... .. ..... .. .. .... .. ... .. .... . by B. Peacock Power Beh in d the Wheel .. .. .. ...... .. .. .... .... .. .. .. ...... ........ .......... by Walter Boyne Alec lssigonis: The Man Who Made the Mini ...................... by Jonathan Wood Buggatti- "Le Pur-Sang Des Automobiles" .............................. by H.G. Conway Streamlined .. . .. .. .. .... .. .. ... .... ... ............. ........ .... ........ .... . ...... by C. Lictenstein Other Useful Design websites www.cardesignnews.com www.cardesignonline.com www.carbodydesign.com www.conceptcar.co.uk

H·POI.'H

l 215

SAMPLE CONCEPT PACKAGE LDGIC DRAWING BE"'TLEY CONTINENTAL GT Sm

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BOOI' CONSTAUCTION ond

CRASHWORTHINESS

lA Very Brief Descr i ption of the Conceptl

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8ENCHMARK STUDIES Show severa! product benchmark studies. 1. Communicate the overall exterior dimensions and proportions. 2. Show the occupant package with interior dimensions 3 . illustrate how the exterior proportlons are lnfluenced by the powertrain 4. Provide additional studies that show attributes or unique features, such as cargo storage and interior flexibility. These studies may also show how the concept differs from other products in the same market segment or vehicles in a brand product line up. Add a description to each study to communicate why the two vehicles have been compared.

MAIN PACKAGE LOGIC DRAWING Show the side and end sectional v ews. Add a pian view if required. Show enough detaìl to describe the basic vehicle architecture and each system. Include the powertrain outline, occupants and interior features. Add a brief written description of the various systems and any special features that are signlficant to the exterior proportions and the Interi or design.

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H-POINT

l 217

ABOUT THE AUTHORS

Stuart Macey Stuart Macey's career in the automotive industry has spanned three decades, deg cars and trucks for aver thirty brands in five countries. He is currently Chief Engineer for Ken Okuyama Design USA in Southern California. Like most car guys, his ion for cars carne from his dad who co-owned a garage (Bailey & Macey) in Portsmouth on the South Coast of England. Some of Stuart's earliest memories were of watching their Formula·3 race car, driven by Rod Banting. al Goodwood In the early '60s. As a child he spent many evenings working on cars wlth his dad, usually holding the torch. Alf was a big fan of Sir Alec lss1gonis and would only drive Morris cars and vans. Stuart would spend hours staring into the engine bay of their Minis and marvel at how Issi packed so much into such a small space. At 16, Stuart started work as an apprentice for Vosper Thorneycroft, building and deg hovercraft structures. In 1979, he transitioned into the car industry as a body engineer and after a few years of training with Pressed Steel Fisher and then Ford Trucks, decided to work freelance overseas as the British car industry went into a rapid decline. At 22. Stuart ed an independent design consultancy in Southern deg for Dalmler-Benz and Audi, then at 23 moved to Detroìt and worked for Chevrolet until1983.

218

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For the next seven years Stuart worked for lnternational Automotive Design, with such clients as Porsche, Volvo, Honda, Renault, Kia, Opel, Mazda, Ford, Daf trucks and Freight Rover. The experience gained from working in studios across Europe was priceless. helping him to understand that although every brand has its own perspec· tlve on design and the process, the bas1c principles are the same everywhere. one of his proudest moments was the unvelllng of the "Mini MPV" at the 1990 Turin Auto Show. He had packaged and styled this small van for IAD (a rare opportunity for an engineer) which has subsequently helped him to design teams with much greater creativity, sympathy and ion. In 1991. he returned to the USA, working with Chrysler at the Design Office at their new technical center In Auburn Hills. After ten years in Mlchlgan, he was transferred to their Pacifica Advanced Design Center in Carlsbad, California for the next seven years. In 2002, Art Center College of Design in Pasadena invited Stuart to develop a new syllabus for t heir Vehicle Architecture class and teach it to the transportation design students. Ken Okuyama was the newly appointed department chair, and having just fìnished deg the Ferrari Enzo, he wanted to put a stronger emphasis on vehicle packaging In the design curriculum. Geoff Wardle and Stuart taught the class together for severa! years and the notes they developed have been compiled for this book.

Geoff Wardle Sìnce graduatlng from the Royal College of Art In 1977, Geoff Wardle has worked as a designer at Brttish Leyland, Chrysler, Peugeot, Saab and Ford of Australia. In addition. he has worked as a consultant designer with a number of companies includfng Tatra in the Czech Republic and TVS Motors, a large lndian motorcycle company. In 1993, Geoff was invited to become the Chair of Transportation Design at the Swiss campus of Art Center Europe, before moving to thelr Pasadena campus In California where he is now Director of Advanced Mobility Research . Growing up in England, he knew from a very early age that he wanted to be involved in creating new kinds of transportation. Surrounded by Dinky Toy models of Foden trucks, Triumph Heralds, London Transport Routemaster buses and Hornby-Dublo Castle class locomotives, he did not really care what kind of transportation they represented because he loved them ali. Nobody in Geoff's life knew what a transportation designer was in those days, and so following advice from others and his own instlncts, he focused on technical subjects at school and sought a piace at an engineering unlversity. Sponsored by the then British Leyland Motor Corporation, and given the choice of studying with their heavy truck division or their car-body engineering division (Pressed Steel Fisher). the perceived glamour of the car industry won aut. However, even to this day, Geoff has equa! ion for large trucks, buses and trai ns.

Ten mìnutes ìnto his first engineering lecture at Hatfield Polytechnic, he knew that he did not want to be an engineer-too much math. Fortunately, through the auspices of one of his tutors, he discovered the world of industriai design and the Automotive Design program at the Royal College of Art in London. This program required a prior degree. which gave him the motivation to successfully complete his bachelor's degree in mechanical and vehicle engineering, speciallzlng in car-body engineering and structural analysls. However, as throughout his educatior, when classmates were busy with their slide rules and calculators, Geoff would more likely be busy sketching cars or trucks on the back of his thermodynamics notes! Although Britlsh Leyland became much maligned, this corporation had many talented designers and engineers working amongst its many divisions, and some of these people encouraged Geoff and taught him many things. Geoff believes that in any successful design team, a variety of designers and studio engineers are needed who contribute different skills or v1ewpoints to a program. There is no doubt that his combination of engineering and design has set him in good stead during his design career, allowing him to push really hard far technical solutions that enabled some of his design proposals to be successfully executed. He has taught the subject of vehicle architecture aver severa! years with Stuart Macey.

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l 219

GLOSSARY There are quite a few that are unique to the auto mdustry, below is a list of words that car designers should be famJiiar with. These are mamly used in design studios in the USA. many of them are universal in most English speaking offices, but expect to hear some varlations depending on the company and country you are worktng in. Axls. (pl.axes) Theoretical llne aboul which a mechanism or wheel rotates. Also, the intersection of the X, Y and Z axes create the origin point for the vehicle's master grid system and determina the grid orientatton.

Curb Weight. The mass of a vehicles including ali fluids, l.e., fuel, lubricants. coolants, etc. Wtth no occupants or cargo. Most vehicles are destgned at "Curb Attitude" srtting on a "Curb Ground Llne."

Apert ures. Openings in the body structure that are used for access into the various compartments, i.e., enger cabin, engine box and trunk.

Datum (Pianes, lines & polnts). Used for reference during the des,gn and build process. These are very important theoretical elemen:s that feature extensiveJy in the package.

Body In Whlt e ( BIW). A complete unpainted body assembly usually made from steel or alumtnum. Back llght. The rear window, not to be confused with the rear lamp. Box sect lons. Load-bearing elements in the body assembly that help to form a strong, light weight structure. ChassJs. Tradittonally this refers to the entrre underbody structure and the components attached, i.e, the suspension, steering, brakes, fuel tank, etc. Since the lntroduction of unit body constructton, most design teams will use thts term to reference the mechanical compcnents only. Closures. Parts of the body assembly that open to allow access. but complete the structure or exterior shape when closed (doors, hoods, trunk ltds and some movat:Je glazing). Cowl. The assembly of s that create the base of the wtndshreld aperture. Cross . Beams lhal run across the body structure mostly under the floor.

220

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Designer. In the auto indust·y this term ts usually reserved for the staff who develop the aesthetics. Flnal drive. The drive shafts and differentisi assembly that transfer power from the transmtssion to the wheels. Fire wall. The bulkhead bet.veen the interior Rnd the engine compartment. separating the engers from heat generated by the engina and a possibJe fire. For most (front engined cars. th s pane! ts in front of the dnver's feet and is called the dash and footwell . Fuel celi. A syslem lhat converts hydrogen fuel into electri city wlthout producing harmful emisslons. This term is also often used in the race car design to describe the gasoline or die!:el fuel tank. Greenhouse. The upper body of a vehrcJe bOdy structure, glazrng, roof systems and trim. GVW. The "Gross Vehicle Weight" wh1ch needs to be considered when setting up ground clearance, brakes, powertrain and suspension. The ·full rated" ground ltne ts used lo show the vehlcle attrtude when lt 1s toaded to the maximum weight.

H-polnt. The reference datum point on the manikin that represents the htp jornt. Al so known as the SgRP (seating reference point) or R point in Europe. Hard polnts. Theoretical points in space that represent parts of system envelopes. These are set up by the engineenng team for the designers to create the CAD or clay models over. HVAC. Acronym for heatrng, ventilation and air condi· tioning system. Thts inctudes the heater box. AC condensar, atr distrlbutlon box. vent ducting an d alr oullets and evacuation vcnts. Homologatlon. To sell cars into any market they must be "Homologated" to that they meet local ·vehicle type approvai" for safety and emissions. Hybrids. \lehrcles wrth more than one power source, usually a combination of internai combustion and elec· tric motors. Jounce. Lpward suspension travel. "Full JOUnce" oocurs when '.he suspenslon is fully compressed. Knee blockers. An area in the lnstrument . in front of the occupants knees, designed to prevent the engers from slidlng forward off the seat dunng a frontal colltS10n when they are not wearing seat belts. Internai Combustion Engine (I.C.E.. ). Most vehicles are powered by engines that produce power from the combustion of fossi l fuels either gasoline or diesel. tnstrument Panet. Often referred t o as Lhe t.P. thls assembly contalns the instruments, switches, air vents, giove box, etc and spans the width of the vehicle interior, in fron: of the front occupants.

Mono-volume. A term used to describe a vehicle that has one main shape (no hood or trunk) in its side view silhouette. Typically micro cars and minivars.

Reach Zones. Theoretical surfaces that represent the limits of whcrc thc dnvcr's honds will comfortubly reach controls.

Three-box. A term used to describe a car or vehicle thut comprises three ma in volumcs: hood, enger compartrnent and trunk.

NCAP. New Car Assessment Program. An tndependent safety program to inform customers about how safe vanous vehicles are. Most manufactures design to meet the ··s star" NCAP standards, which are higher than most government requlrement s, to market their cars to educated consumers.

Rebound. Downward suspension travel.

Transmlsslon. Transm1ts lhe power from lhe engine to the final drive through a series of reduction gears speeds can be changed automatìcally or manually.

Package (Packaglng). Ali of the elements in t he vehic e architecture thal are driven by function, not style. Packaglng is a function performed by the of the design team who set up the vehicle architecture.

Sectlons. These are cut on ftat planes through the architecture to show ho.v the components are conflgured. They are also used as a 20 media for design and manufacture. "Car Une· sections are cut parallel to the grid planes (X,Y an:! Z) lf they are cut out of grid they are called "radiai or "compound radiai" sections. A sectional v1ew IS similar to a section but a iso shows visible details behind the section piane.

Plllars ( ..A, B ,C, D, etc" ). The elements in the body structure that create the door or glazing apertures, between the underbody structure and the roof. Pl & P2 Curves. The curves that represent the openlng of the s1de door aperture s in the body structure. They are usually the "heel and toe" of the weld flange which the seals are mounted to. Plenum. The enclosed chamber usually at the base of the windsh1eld that helps to remove mc1sture and large part1cles from fresh air that is drawn into lhe veh1cle's heat1ng and ventilation syst em. This often becomes a structural element. Powertraln. The combination of the engine, gearbox and f1nal dnve system that create and transmit power to the wheels. Rails. Beams that run longltudinally in the body structure, i.e .. roof rails. underbody frame rails, etc.

S.A.E. (Society of Automobile Englneers) An international. network of vehicle engineers, that works to share and publish mformat1on, to improve vehicle functiona llty and des1gn processes.

Sills. The structural box sections under the doors that stretch from the front to the rear wheels. Splndles. The shafts that the wheels revolve around square to the grid. they Because these are not are aften represented as po1nts which are used as main reference datums to represent the wheel centers.

Tumblehome. The angle and curvature of lhe upper body side as the surface leans ìn towards the center line. Vehicles wilh upright slde glass are sa1d to have "stiff tumblehome". This lerm has been used in the shipbuildlng industry for hundreds of years to describe hull curvature above the water line. Two-Box. A term used to descnbe a vehlcle that com pnses two main volumes; typically a hatchback or station wagon. Unibody. (Unlt-body or monocoque) A car bodt structure rrade ent1re1y from pressed-steel or aluminum sheets that is rig1d enough not to require a separate chassis frame. Mechamcal components are attached to subframes (cradles) or directly to the unibody structure.

Telematlcs. lnformation or data that is relayed by Wlreless means. The telemalic systems 1nclude satellite navigation and audio/video eqUipment . Tire Envelopes. These are volumes calculated by the chassis engineers to describe the lire profile as it is tranclatcd by cucnsion trovcl ond stccring. Thc cnvclopes also include build tolerancing. flex(compliance) and snow chains if requlred.

H·POINT

l 221

IN DEX

A accelerator piane 91 accommodation curve 91 aerodynamics 193 all-wheel drive (AWO) 124. 128 alumirum extrusions 175 ant1 roll bar 160-163 A Pllla· 170 approach angle 199 aspect ratio 139, 140

8 back angle 91 backbone structure 169 backlight 189 bali of foot 91 battenes 117, 133 beam axle 157. 159 bench1larkmg 82, 84 body, less doors 170 body on frame 168 body side 184 B Pillar 170 brake cal1per 143 brake cooling 192 brake horsepower (BHP) 120 brake rotor 143 breatrlng apertures 192 bumper band 198 bumper offset 195, 198 bumpers 195, 198

c

camber 158-163 cargo 34. 110 chair height 91,93 chapman struts 161 closures 68, 176-185 coil spring 154-163 commerciai vans 59

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contro! arms 160-163 controls 99-104 cooling 116, 192 cooling module 116 cowl plenum 170 C Pillar 170 crush space 76. 171. 173 curb attitude 41 curb ground Ime 41 curb weight 41 customers 49, 51 cylinder block 123

D dash 170 decklid 177 departure angle 199 design process 22 dimensions 78-81, 94 OLO (daylight opening) 200 door aperture 179, 184 doors (See closures) door constructiOn 1/6 down angle 91 drag coefficient 192 dropping glass 184

E economy cars 56 effective headroom 81, 113 electric motors 132 engines (ICE) 116-133 engine box (bay) 76, 126, 170 engine configuratlons 123-133 Environmental Protection Agency 172 European Commission (EC) 172 exnaust system 116 exterior lighting 194-197 eye ellipse 91 t:y..: poinl::. 187

F fascia 198 frame rails 170, 128 federai motor vehlcle standards 172 fìnal drive 116, 126-133 frit (blackout) 200 front fender 170 front-wheel dnve (FWD) 126 fuel celi 117. 132 fuel consumpt1on 49. 193 fue l tank 135 full lock 126, 140, 148, 152 functronal ObJectives 48

G

glass 184, 200 grid planes (lines) 40 gross vehicle weight (GVW) 41, 49, 75 ground clearance 41, 42, 199 ground planes (lines) 41

H hardpoints 42 head contours (forms) 91, 184 header 170,189,200 headiight 195 headliner 94, 99. 113. head swing 91, 184 heavy duty truck 59, 120 heel point 91, 93 height (see overall height) HVAC 99 high-speed impact 76, 171,173 hinges 176, 181 , 185 history 12-19 hood 175, 177 H-point (SgRP) 91 hybrids 133

IIHS 115 impact test 173 lmpact structure 76, 171, 173 independent suspension 155 internai combustion engine (see engines) ISO 172

J Jounce travel 142, 144, 147

L lamps (see extenor lightrng) leaf springs 157 legislation 172 leg room 92, 113 length 76 llcense plate pockets 203 liftgate 184 lighting (see exterior lighting) live axle 156 load floor 108 load paths 170 luggage 110 luxury cars 57

M manufacturing 49 mass production 14 market segments 25. 52-59 Mherson strut 161 micro cars 56 midsize cars 56 minivans 58 mobillty 206 monocoque 168 motors (see engines) multi-lìnk 163

N NCAP (New Car Assessment Program)

172 NHTSA (Natlonal Hìghway Transporta· tion Safety Association) 172 non-independent suspension 154

o

objectives 48 occupants 88-94 offset Impact 173 output shaft 126-133 overali height 79, 80 overall width 78, 80 overhang 76

p package (drawing) 45, 216 package anatomy 26 package ideation 62-69 panhard rod 159 pedestrian impact 173 pickup trucks 59 pillar obscuration 187 plastìc composìtes 17 4 power 120 power curve 120 powertrain 116 proportion 72

A

rack and pinlon 149 ram p over angle 42, 199 range 49,134 rear header 170, 189 rear quarter 170 rearward vision 189 rear-wheel drive (RWD} 57.127-130

rebound 152 recirculating bali 149 reference datum 40, 89 ride heìght 41 rolling resistance 138 rollover 1f3 roof 170, 173, roof crush 39, 179 roof rail 39, 170, 184 R point (see H point) run flat tires 145

s

SAE 40,91,102,199 safety regulations 171 scrub radius 142 seatlng reference point (see H-polnt) sectional view 39 sections 39, 191 segments (see market segments) SgRP (see H point) shock absorbers 152 short & long arm (SLA) 154, 102 shoulder room 78. 81, 94, 113 side impact 173,179, 184, side lntrusion beams 184 sill 170,179,184,191 solid axle 156 space frames 169 spare tire 145 splndle 80, 144 spoilers 192 spoke design 143 spot weldlng 168, 175 springs 154-163 static load radlus (SLR) 42, 140 steering angles 126,148 steerlng axis 142 steenng column 149 steering geometry 148

steering knuckle 142 steering systems 149 steering wheel 102 step-by-step process 29-37 step-in height (see step over) step over 18 f, 190, 198 storage 111 structural analysis 167 structure 167 strut tower 170 suspension 152-163 suspension articulation 157-163 suspension system attributes 153 suspension travel 142, 147, 153, SUVs 58 sway bar 160-163 swing arms 156,158

T

target specifications 49, 64 tires 138, 14 7 tire coverage 146 tire O. D. 80, 140 tire profile 138, 144 top speed 49, 64, 120, 192 torque 120 torsional rigidity 168 torsion bar 162 towing capacity 168,120, 49 track 78, 80 traction 118, 139 trailing arm 158 transmission 116, 124-133 trim 39, 99, 101, 113, 184, 200 trunk 110,145.177, turn circle 148 twlst beam 159 typical sections (see sections)

u

underbody 170 unibody 168 up angle 81, 91, 200

v

vehicle attitudes 41 vehicle classificatlon 73-75 vehicle positioning 53 vehlcle types 54-59 visibility 81, 86, 89 vision angtes 81, 91, 200 vision studies (see Vlsibility)

w

weight distribution 57, 72, 152 wheelbase 76 wheel house 142,144,147,182 wheels 138-148 wheel spokes (see spoke design) width (see overall width) windshield 193.201 windshield aperture 200 windshield lnstallation angle 200

H-POINT

l 223

e

Art Center College of Design

In 1930, when Art Center College of Des1gn was first established, Los Angeles was already a destination for art and entertainment, architecture and even aircraft development. G1ven the desirable clima te and geography, it was al so a center for experimentat1on In automotlve performance, as well as beautifully deslgned coach-built cars for clients desiring personal expresslon. Automobile design was part of the design education at Art Center in the 1930s with graduates ing the new Generai Motors styhng activity. In 1948. wher Strother MacM1nn ed Art Center, the program was formalized. Emphasis on the complete veh1cle layout or architecture was an 1mportant part of the education from the beg1nn1ng. The automot1ve and transportation industry is in a time of profound change. The designer's role now engages many technologies, as well as influencmg marketing and business innovalion. This book was conceived to help Art Center students continue to be successful and innovat1ve designers by complementing the1r veh1cle architecture classes. We are confident many others will find 1t very useful as well. Stewart Reed Chair, Transportation Design Art Center College of Design

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