Page 18 - Understanding Automotive Electronics

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AUTOMOTIVE FUNDAMENTALS 1

Evolution of Electronics in the Automobile

This book explores the application of modern solid-state electronics to
the various automotive subsystems described above. Apart from auto radios,
some turn signal models, and a few ignition systems, there was very little use
of electronics in the automobile until the early 1970s. Government-mandated
emission regulations, fuel economy, and safety requirements motivated the
initial use of electronics. The dramatic performance improvements and
relatively low cost of electronics have led to an explosive application of
electronics in virtually every automotive subsystem. We will be exploring these
electronic systems in great detail later in this book, but first it is helpful to
review the basic mechanical configurations for each component and
subsystem.
THE ENGINE
The engine in an automobile provides all the power for moving the
automobile, for the hydraulic and pneumatic systems, and for the electrical
system. A variety of engine types have been produced, but one class of engine is
used most: the internal combustion, piston-type, 4-stroke/cycle, gasoline-
fueled, spark-ignited, liquid-cooled engine. This engine will be referred to in
this book as the spark-ignited, or SI, engine.
Although rapid technological advances in the control of the SI engine
have been achieved through the use of electronics, the fundamental mechanical
configuration has remained unchanged since this type of power plant was first
invented. In addition, the introduction of modern materials has greatly
improved the packaging, size, and power output per unit weight or per unit
volume. In order that the reader may fully appreciate the performance
improvements that have been achieved through electronic controls, we illustrate
the engine fundamentals with an example engine configuration from the pre-
electronic era.
Figure 1.2 is a partial cutaway drawing of an SI engine configuration
commonly found in the period immediately following World War II. The
engine there illustrated is a 6-cylinder, overhead-valve, inline engine. An engine
of this configuration is rarely found in present-day cars. Rather, a more
common engine configuration today would be either a 4-cylinder inline or a V-
type engine with either 6 or 8 cylinders (although there are exceptions).
Moreover, the materials found in present-day engines permit greatly reduced
weight for a given engine power.
Nevertheless, modern electronically controlled engines have much in
common with this example configuration. For example, the vast majority of
modern engines are 4-stroke/cycle, gasoline fueled, spark ignited, and water
cooled. By illustrating the fundamentals of engine operation using the example
engine of Figure 1.2, we can thus explain the differences that have occurred
with modern electronic controls.

UNDERSTANDING AUTOMOTIVE ELECTRONICS 5