Understanding Automotive Electronics P1 ppt

Since the introduction of electronics for emission control on engines, theevolution of electronics in automobiles has advanced rapidly.. Electronics have become standard implementation f

Understanding Automotive

Electronics

Understanding Automotive

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Library of Congress Cataloging-in-Publication Data

Ribbens, William B

Understanding automotive electronics / William B Ribbens ; with contributions

to previous editions by Norman P Mansour [et al.] — 6th ed

p cm

Includes index

ISBN 0-7506-7599-3 (pbk : alk paper)

1 Automobiles—Electronic equipment I Mansour, Norman P II Title.TL272.5 R45 2002

629.2¢7—dc21

2002034651

British Library Cataloguing-in-Publication Data

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To Katherine

Preface ix

Chapter 1 Automotive Fundamentals 1

Quiz 33

Chapter 2 The Systems Approach to Control and Instrumentation 35

Quiz 76

Chapter 3 Electronics Fundamentals 79

Quiz 106

Chapter 4 Microcomputer Instrumentation and Control 109

Quiz 155

Chapter 5 The Basics of Electronic Engine Control 157

Quiz 195

Chapter 6 Sensors and Actuators 199

Quiz 238

Chapter 7 Digital Engine Control Systems 241

Quiz 285

Chapter 8 Vehicle Motion Control 287

Quiz 324

Chapter 9 Automotive Instrumentation and Telematics 327

Quiz 365

Chapter 10 Diagnostics 367

Quiz 399

Chapter 11 Future Automotive Electronic Systems 401

Quiz 441

Glossary 443

Answers to Quizzes 449

Index 451

vii

Since the introduction of electronics for emission control on engines, theevolution of electronics in automobiles has advanced rapidly The pace ofdevelopment has inspired five revisions of this book in roughly twenty years toavoid obsolescence Rarely in history have technical developments moved atsuch a pace

Electronics have become standard implementation for control on allmodern vehicles impacting virtually all automotive subsystems Such features

as powertrain control, vehicle motion control, antilock braking systems, andairbags could only be achieved practically through the use of electronics Thesefeatures have become standard features in the highly competitive NorthAmerican automotive market

The first edition of this book was devoted primarily to electronic enginecontrol because this was the chief application at that time A number ofautomotive systems which were discussed in the chapter on the future ofautomotive electronics in the second, third, fourth, and fifth editions are now

in production These systems are presented in the appropriate chapters of thisfifth edition This latest edition covers the automotive subsystems

incorporating electronics except for entertainment systems These systems havebeen omitted partly due to space limitations and because automotive

entertainment systems are closely related to home entertainment systems,which are discussed in many excellent publications

In its revised form, this book explains automotive electronics as of 2001

It should prepare the reader for an understanding of present as well as futuredevelopments in this field into at least the early part of the twenty-first century

William B Ribbens

ix

Automotive Fundamentals

Picture yourself in the not-too-distant future driving your new car along

a rural interstate highway on a business trip You are traveling along one of thenew automated highways in which individual cars are controlled electronically

to maintain a fixed spacing in a lane at a preferred speed Typically, these carsare traveling at 70 mph and are spaced about 25 ft apart The cars are computercontrolled via a digital communication link, including a cable buried in thecenter of the “cruise” lane and follow one another in a pattern known asplatooning Your car will automatically remain in this cruise control lane untilyou approach your destination exit

You press a button on the steering column and an image of a road mapappears faintly visible (so as not to obscure the road ahead) on the windshield

in front of you This map shows your present position and the position of thedestination city The distance to your destination and the approximate arrivaltime are displayed on the digital instrument cluster

You are talking on your cellular phone to your office about some changes

in a contract that you hope to negotiate You are wearing a lightweight headsetthat enables you to use the cell phone “hands free” to drive Dialing is accom-plished by voice command using voice recognition software in your cell phonecontroller After the instructions for the contract changes are completed, aprinter in your car generates a copy of the latest contract version

Your spouse (in the passenger seat) is sending e-mail messages using theon-board computer that is linked by radio to the Internet Your son (in the rearseat) is watching a movie via an interactive digital link, while your daughter(also in a rear seat) is doing a math lesson from an education center with aninteractive video link

After you finish your phone call, the onboard entertainment system startsplaying music for you at a comfortable level relative to the low-level wind androad noise in the car After completing your phone conversation, you pressanother button on the steering wheel and the music is replaced by a recordedlesson in French verb conjugation, which you have been studying Suddenly,the French lesson is interrupted by a message delivered in natural-soundingsynthesized speech “You have fuel remaining for another 50 miles at thepresent speed Your destination is 23 miles away Recommend refueling afterexiting the highway There is a station that accepts your electronic credit nearthe exit (you know, of course, that the electronic credit is activated by insertingthe fuel nozzle into the car) Also, the left rear tire pressure is low and theengine control system reports that the mass air flow sensor is intermittentlymalfunctioning and should be serviced soon.’’ After this message has beendelivered, the French lesson returns

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A short time later, the French lesson is again interrupted by the electronicvoice message system: “Replace the disk in the Navigation CD player with disknumber 37 for detailed map and instructions to your destination, please.’’Then the French lesson returns.

You insert the correct disk in the Navigation CD player as requested andthe map display on the windshield changes The new display shows a detailedmap of your present position and the route to your destination As youapproach the city limits, the car speed is automatically reduced to the legallimit of 55 mph The voice message system speaks again: “Leave the highway atexit 203, which is one-half mile away Proceed along Austin Road to thesecond intersection, which is Meyer Road Turn right and proceed 0.1 mile.Your destination is on the right-hand side of the road Don’t forget to refuel.’’

This scenario is not as farfetched as it sounds All of the events describedare technically possible Some have even been tested experimentally Theelectronic technology required to develop a car with the features describedexists today The actual implementation of such electronic features will depend on the cost of the equipment and the market acceptance of thefeatures

USE OF ELECTRONICS IN THE AUTOMOBILE

For most people, the automobile has come to be an appliance It isarguably the most cost effective, most user friendly of appliances availabletoday The personal computer industry likes to refer to its products as userfriendly However if the automobile had the same user friendliness as a PC, itwould arrive in six or more large boxes and require the owner to install theengine wheels and seats and load the programs into its various electronicsystems and the documentation would be unreadable Moreover, in use itwould break down every 100 or so miles This comparison is offered tongue

in cheek, but it does illustrate the relatively high reliability of modernautomobiles with their various electronic subsystems Although its utility isprimarily for transportation, the new automobile electronics can give it a broad range of auxiliary capabilities, as will be illustrated in this book

EVOLUTION OF AUTOMOTIVE ELECTRONICS

Electronics have been relatively slow in coming to the automobileprimarily because of the relationship between the added cost and the benefits.Historically, the first electronics (other than radio) were introduced into thecommercial automobile during the late 1950s and early 1960s However, thesefeatures were not well received by customers, so they were discontinued fromproduction automobiles

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Microelectronics

will provide many

excit-ing new features for

automobiles

Two major events occurred during the 1970s that started the trendtoward the use of modern electronics in the automobile: (1) the introduction

of government regulations for exhaust emissions and fuel economy, whichrequired better control of the engine than was possible with the methods beingused; and (2) the development of relatively low cost per function solid-statedigital electronics that could be used for engine control and other applications.Electronics are being used now in the automobile and probably will beused even more in the future Some of the present and potential applicationsfor electronics are

1 Electronic engine control for minimizing exhaust emissions andmaximizing fuel economy

2 Instrumentation for measuring vehicle performance parameters and fordiagnosis of on-board system malfunctions

3 Driveline control

4 Vehicle motion control

5 Safety and convenience

6 Entertainment/communication/navigationMany of these applications of electronics will be discussed in this book

CHAPTER OVERVIEW

This chapter will give the reader a general overview of the automobilewith emphasis on the basic operation of the engine, thus providing the readerwith the background to see how electronic controls have been and will beapplied The discussion is simplified to provide the reader with just enoughinformation to understand automotive mechanics Readers who want to knowthe mechanics of an automobile in more detail are referred to the many bookswritten for that purpose

THE AUTOMOBILE PHYSICAL CONFIGURATION

The earliest automobiles consisted of carriages (similar to those drawn byhorses) to which a primitive engine and drivetrain and steering controls wereadded Typically, such cars had a strong steel frame that supported the body ofthe car The wheels were attached to this frame by a set of springs and shockabsorbers that permitted the car to travel over the uneven road surfaces of theday while isolating the car body from many of the road irregularities Thissame general configuration persisted in most passenger cars until some timeafter World War II, although there was an evolution in car size, shape, andfeatures as technology permitted Beginning in the late 1960s, governmentregulations imposed severe design constraints on automobiles that led (as will

be shown) to an evolution of electronic systems in automotive design It is thisevolution that is the primary focus of this book

3

Environmental

regula-tions and an increased

need for economy have

resulted in electronics

being used within a

number of automotive

systems

For the remainder of this chapter, the basic automobile components andsystems are reviewed as they pertained to the post–World War II, preemissions-control era This review provides a framework within which the present dayautomobile with its extensive use of electronics can be understood In thissense, the motivation for applying electronics to solve regulatory problemsimposed on the industry can readily be seen Readers with a solid background

in basic automotive systems may want to skip the remainder of the presentchapter

This early configuration is depicted in Figure 1.1, in which many of theimportant automotive systems are illustrated These systems include thefollowing:

This basic vehicle configuration was used from the earliest cars throughthe late 1960s or 1970s, with some notable exceptions The increasingimportance of fuel efficiency and government-mandated safety regulations led

to major changes in vehicle design The body and frame evolved into anintegrated structure to which the power train, suspension, wheels, etc., wereattached

Once again with a few notable exceptions, most cars had an engine in afront configuration with the drive axle at the rear There are advantages inhaving the engine located in the front of the vehicle (e.g., crash protection,efficient engine cooling) Until recently, the so-called drive wheels throughwhich power is delivered to the road have been the rear wheels (as depicted inFigure 1.1) This configuration is known as rear wheel drive For safety andstability the front wheels are used to steer the vehicle

This rear wheel drive configuration is not optimal from a tractionstandpoint since the relatively large weight of the engine/transmission is

4

primarily on the front wheels In order to take advantage of the engine weightfor traction, many present-day cars combine steering and drive wheels in thefront (i.e., so-called front wheel drive cars) In achieving front wheel drive,certain compromises must be made with respect to complexity and steeringradius Moreover, there is a tendency for the torque applied to the front wheels

to adversely affect steering through a phenomenon known as “torque steer.”Nevertheless, the technology of front engine front wheel steering is quitemature and has become commonplace in modern cars

In front wheel drive cars the engine is mounted transversely (i.e., with the rotation axis orthogonal to the vehicle axis as opposed to along thevehicle axis) In automotive parlance the traditional engine orientation is

5 Figure 1.1

Systems of the Automobile

referred to as North-South, and the transverse orientation as East-West The

transmission is mounted adjacent to the engine and oriented with its axisparallel to the engine axis The differential and drive axle configuration isnormally mounted in the transmission; the combined unit is thus called the

transaxle.

All of the systems listed above have been impacted by the introduction ofelectronics The evolution of these electronics has been so rapid that a booksuch as this requires continuous revision to have any hope of reflecting thelatest state of the art New applications of electronics to each of the abovesystems continually supplement those already in use resulting in anenvironment in which electronics represents something of the order of 20%

of the cost of a modern car

Evolution of Electronics in the Automobile

This book explores the application of modern solid-state electronics tothe various automotive subsystems described above In order to give theevolution of electronics in automobiles a suitable perspective, it is helpful toconsider the history of automotive electronics Apart from auto radios, someturn signal models, and a few ignition systems, there was very little use ofelectronics in the automobile until the early 1970s At about this time,government-mandated emission regulations, fuel economy, and safetyrequirements motivated the initial use of electronics The dramatic perfor-mance improvements and relatively low cost of electronics have led to anexplosive application of electronics in virtually every automotive subsystem.The relative cost/benefit of electronic subsystems in automobiles is largelyaffected by the production volume (Some 15 to 16 million new cars and lighttrucks are sold in the United States each year.) Such a large production volumesignificantly lowers the unit cost for any electronic system relative to aerospacevolumes

SURVEY OF MAJOR AUTOMOTIVE SYSTEMS

We will be exploring these electronic systems in great detail later in thisbook, but first it is helpful to review the basic mechanical configurations foreach component and subsystem Modern automotive electronics were firstapplied to control the engine in order to reduce exhaust emissions andsomewhat later to improve fuel economy Consequently, we review the engineconfiguration first in this survey

THE ENGINE

The engine in an automobile provides all the power for moving theautomobile, for the hydraulic and pneumatic systems, and for the electricalsystem A variety of engine types have been produced, but one class of engine

is used most: the internal combustion, piston-type, 4-stroke/cycle,

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