Automotive
Electrical and
Electronics
A K BABU
Associate Professor
Department of Mechanical Engineering
PERI Institute of Technology
Chennai
KHANNA BOOK PUBLISHING CO. (P) LTD.
Publisher of Engineering and Computer Books
4C/4344, Ansari Road, Darya Ganj, New Delhi-110002
Phone:
011-23244447-48 Mobile: +91-99109 09320
E-mail:
contact@khannabooks.com
sales@khannapublishers.com
Website: www.khannabooks.com, www.khannapublishers.com
Price: ` 295.00
Automotive Electrical and Electronics
A K BABU
Copyright © Khanna Book Publishing Co. (P) Ltd.
This book is sold subject to the condition that it shall not, by way of trade or
otherwise, be lent, resold, hired out, or otherwise circulated without the publisher’s
prior consent in any form of binding or cover other than that in which it is published
and without a similar condition including this condition being imposed on the
subsequent purchaser and without limiting the rights under copyright reserved
above, no part of this publication may be reproduced, stored in or introduced into
retrieval system, or transmitted any form or by any means (electronic, mechanical,
photocopying, recording or otherwise), without the prior written permission of both
the copyright owner and the above mentioned publisher of this book.
ISBN: 978-93-82609-69-8
Edition: 2016
Published by:
KHANNA BOOK PUBLISHING CO. (P) LTD.
4C/4344, Ansari Road, Darya Ganj, New Delhi-110 002
Phone: 011-23244447-48 Mobile: +91-9910909320
E-mail: contact@khannabooks.com
Typesetted by:
M2W Media, Daryaganj, Delhi
Printed in India by:
S.P.S. Printers & Binders, Delhi
PREFACE
This book is designed for the core subject “Automotive Electrical
and Electronics” offered to the under graduate and post graduate
students of Automobile Engineering of various engineering colleges
and universities in India. My aim is to provide a broad understanding
of the many systems and component parts that constitute the vehicle
electrical and electronics in a detailed way. The book should also be
a valuable source of information and reference.
The book provides clear explanation of vehicle electrical and
electronic components and systems with unique illustrations, which
should be of value both to the students and to the experienced faculty
members. Each chapter takes the reader systematically through the
details of each component system. Key topics are emphasized and
are reinforced by numerous illustrations.
I hope that students and teachers enjoy reading this book and
that they find its contents informative and useful.
A K BABU
Acknowledgement
Acknowledgements for this book are difficult to make because many
books and manuals have influenced me directly or indirectly in
its preparation. I express my grateful thanks to all those authors,
publishers and manufacturers.
I owe a huge thanks to Dr.V.Antony Aroul Raj, Easwari Engineering
College and Dr.G.Kumaresan, Institiute of Energy Studies, Anna
University for providing excellent support and advice.
I am grateful to my professor Dr.S. Parthasarathy, who never tired
of my requests, doubts and questions, and supported me throughout
this project.
I am grateful to my wife Sharmila Babu, who constantly encouraged
me for completing this book. I also thank my wonderful children
Vishal Surya S.B. and Harshitha S.B., for always making me smile
when I was writing this book.
I am grateful to my parents, Shri A.Krishnamoorthy and Srimati
K.Savithri, who put me in Engineering education.
I would really like to thank Khanna Publications for providing me
with the opportunity to become the lead author for this book.
Contents
Prefacev
Acknowledgementvii
1. Fundamentals of electricity
1
Electricity1
Elements of electricity
3
Ohm’s law
4
Electric circuits
5
Dc measuring instruments
6
Actions of electric current
8
Voltage generation by electromagnetic induction
10
Voltage generation by electro-chemical cells
10
Voltage generation by heat (thermo element)
10
Voltage generation by light (photoelectric cells)
11
Voltage generation by pressure (piezo-electric effect)
11
2. Vehicle electrical system
12
Generation system
12
Starting system
13
Ignition system
13
Lighting system
14
Accessories14
3. Battery15
Vehicle battery
15
Functions16
Principle16
Construction of a lead-acid battery
17
Cell and battery arrangements
26
Electrochemical action
27
Alkaline battery
29
Sodium-sulphur battery
31
Aluminum-air battery
32
Performance characteristics of a lead-acid battery
32
Battery rating and capacity
38
Battery efficiency
40
Various tests on battery
41
Battery charging
45
Maintenance of batteries
51
4. Starting system
Starting requirements
Starter motor
54
56
59
6
Automotive Electrical and Electronics
Requirements of starter motor
59
Principle59
Starter construction
60
Conventional starter motor
62
Reduction type starter motor
63
Types of starter motor
65
Characteristics of starter motor
67
Starter drive mechanisms
70
Overrunning clutch
77
Starter switches
79
Starter solenoid
79
Starter relay
82
5. Charging system
85
Operation86
Requirements86
Generator86
Direct-current (dc) generator
87
Regulator89
Alternator 92
Construction93
Principle of alternator
97
Advantages of alternator
97
Single-phase and three-phase alternators
98
Voltage regulator
99
Compensated voltage regulator
103
Regulator characteristics
104
6. Ignition system
109
Functions and requirements 109
Ignition energy
110
Principle of high voltage generation
110
Components of conventional ignition system
112
Ignition coil
113
Distributor114
Conventional ignition systems
120
Comparison of battery ignition and magneto ignition
123
Ignition advance mechanisms
123
Spark plug
129
Ignition performance
131
Self-cleaning temperature
133
Pre-ignition temperature
133
Spark plug heat flow
134
Spark plug reach
134
Nose length and heat range
135
Projecting-electrode spark plugs
136
Platinum-tipped spark plugs
137
Contents
7
7. Electronic Ignition system
141
8. Automotive wiring
160
9. Lighting system
172
Capacitive discharge ignition system
141
Solid state transistorized ignition system
142
Distributor less ignition (dli) system (fully electronic)
145
Triggering devices (signal generators)
146
Igniter151
Digital ignition system
151
Electronic spark advance (esa)158
Automotive wiring and circuits
160
Earth return system
160
Insulated earth return
161
Positive and negative earth systems
161
Wire163
Wire gauge (wire size)
163
Metric wire system and american wire gauge (awg) system.
164
Necessities of selecting wire gauges
165
Current density 165
Measurement of the gauge of a cable 166
Colour coding of electrical wires
168
Wiring harness168
Headlight Signal lights Interior lights
Low beam and high beam operation
Headlight aiming Headlamp arrangement
Headlight dazzling
Methods to reduce dazzling
Directional warning lamps
172
174
177
178
180
183
184
185
187
10.Accessories192
Dashboard instruments
192
Speedometer193
Fuel gauge
200
Temperature gauge
206
Horn208
Components of hot water heater
224
11.Electronic Engine management
Sensors in engine management
Mass air-flow sensor
Manifold pressure sensor
Position/speed sensors
233
234
235
237
239
8
Automotive Electrical and Electronics
Throttle position sensor
242
Oxygen sensor (lambda sensor)
243
Temperature sensors
251
Detonation sensor
253
Electronic control unit (a microcomputer)
254
Actuators255
Feedback carburetor
256
Electronically controlled gasoline injection system
258
Types of electronic fuel injection systems
258
Electronic fuel injection system for a diesel engine
263
12.Safety and Warning systems
268
Automobile safety
268
Airbag268
Anti-lock brake system (abs)269
Traction control system (tcs) or vehicle
stability assist (vsa) system270
Tyre pressure monitoring systems (or)
deflation detection system
272
Electronic stability control
275
Adaptive cruise control
277
Emergency brake assist systems
277
Rearview cameras
278
Voice warning system
279
Travel information system
283
Keyless entry system
284
13.Vehicle electronics
Electronic dash board instruments
Electronic power steering
286
286
286
Vehicle cruise control
288
Vehicle navigation
288
Automatic air conditioner
289
Functional components
290
Sensors290
Controllers293
Actuators294
Index295
U N I T
1
Fundamentals
of Electricity
The components of the automobile electrical system are of complicated
construction, but all of them are applications of the various actions made
possible by the flow of electricity. Before taking up the construction and
operation of these various electric components, the fundamentals of
electricity will first be reviewed.
ELECTRICITY
Electricity is a form of energy and is produced by the movement of
small atomic particles known as electrons. It can be easily transmitted or
converted to other forms, such as mechanical or heat energy. To transmit
electricity, conductors such as copper, steel, carbon or an electrolyte are
used. Insulators such as rubber, porcelain or bakelite are used to prevent
electrical leakage from conductors.
There are two kinds of electricity: static and dynamic. Dynamic
electricity can be further divided into direct current (DC) and alternating
current (AC).
Static electricity
Electricity
Direct
current (DC)
Dynamic
electricity
Alternating
current (AC)
2
Automotive Electrical and Electronics
Static Electricity
When a non-conductive substance such as a glass rod is rubbed with a
silk cloth, the surfaces of both the rod and the cloth become charged with
electricity, one positively and one negatively. Unless the two materials
touch, or are connected by a conductor, the electrical charge will remain in
the glass rod and silk cloth. Since it does not move, this type of electricity
is called static electricity.
Charged with
static electricity
Glass rod
+
+ +
+
–
–
–
+
–
–
Silk cloth
Fig.1.1: Static electricity
In terms of free electron, static electricity refers to a state in which free
electrons are separated from their atoms and do not move about on the
surface of the substance.
Dynamic Electricity
Dynamic electricity refers to a state in which there is a flow of free electrons,
i.e. electrons that are separated from their atoms and moving about inside
the conductive substance.
–
+
–
–
–
0
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
Time
DIRECT CURRENT
–
–
–
+
0
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
Time
_
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
ALTERNATING CURRENT
Fig.1.2: Dynamic electricity
When the free electrons are moving in a constant direction, the state
of dynamic electricity is called direction current (DC). When the direction
of motion and the size of the current vary periodically with time, the state
of dynamic electricity is called alternating current (AC).
3
Fundamentals of Electricity
ELEMENTS OF ELECTRICITY
The three elements of electricity are voltage, current and resistance.
Current
Electric current is a flow of electrons and is measured in amps, (short for
amperes). The amp is a measure of flow rate. In other words how much
electricity is flowing per second.
–
–
–
MOVING ELECTRONS
Fig.1.3: Current
1 amp = 6,240,000,000,000,000,000 electrons per second
In electronic circuits a current of one amp is quite large, so often
the milli-amp is used instead. A milli-amp (mA) is a thousandth of an
amp (A).
Voltage
Voltage
–
–
–
– –
–
–
– –
– – –
–
–
–
–
–
–
–
–
–
–
–
Fig.1.4: Voltage
Electricity does not flow through a wire unless it is pushed. There
has to be an electrical pressure and this pressure is called voltage and is
measured in volts. The symbol is V. It is also called electrical pressure, and
electromotive force (emf). This pressure can be provided by a battery, or it
can be produced by a generator.
Resistance
Voltage
–
– – –
–
–
–
– – –
–
–
Fig.1.5: Resistance
–
–
4
Automotive Electrical and Electronics
The rate that the electrons pass around the circuit (i.e. the amount of
current) is dependent not only on the force (voltage) but also by how much
resistance there is in the circuit. Resistance is measured in ohms (W).
In the case of electricity, a same conductor will allow better current
flow when its diameter becomes larger due to less resistance. When it
becomes longer, its resistance increases so that the current gets weaker.
That is, the resistance of a conductor is directly proportional to its length
and inversely proportional to its cross-sectional area. Because in a car the
same 12V battery powers all circuits, the only way that current can vary is
by varying the resistance.
The conductor resistance normally changes with the temperature.
The resistances of metal conductors increase when the temperature rises,
but resistances of carbon and aqueous solutions decrease. The resistance
also varies with the conductor material. A good conductor will have small
resistance, whereas the resistance of insulating material will be enormous.
OHM’S LAW
Increase resistance
Water
Water pipe
Resistor
Current
Fig.1.6: Ohm’s law
In 1827, George ohm introduced simple mathematical formula, which
relates voltage, current, and resistance. This formula is called ohm’s law.
Ohm’s law says voltage is equal to current times resistance. A force of 1V
is required to push a current of 1A through a resistance of 1Ω .
V=I×R
Where,
V = Voltage in volts
I = Current in amperes
R = Resistance in ohms