Page 16 - Understanding Automotive Electronics

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AUTOMOTIVE FUNDAMENTALS 1

applied. The discussion is simplified to provide the reader with just enough
information to understand automotive mechanics. Readers who want to know
the mechanics of an automobile in more detail are referred to the many books
written for that purpose.
THE AUTOMOBILE PHYSICAL CONFIGURATION
The earliest automobiles consisted of carriages (similar to those drawn by
horses) to which a primitive engine and drivetrain and steering controls were
added. Typically, such cars had a strong steel frame that supported the body of
the car. The wheels were attached to this frame by a set of springs and shock
absorbers that permitted the car to travel over the uneven road surfaces of the
day while isolating the car body from much of the road irregularities. This same
general configuration persisted in most passenger cars until some time after
World War II, although there was an evolution in car size, shape, and features as
technology permitted.
This early configuration is depicted in Figure 1.1, in which many of the
important automotive systems are illustrated. These systems include the
following:
1. Engine
2. Drivetrain (transmission, differential, axle)
3. Suspension
4. Steering
5. Brakes
6. Instrumentation
7. Electrical/electronic
8. Motion control
9. Comfort/convenience
10. Entertainment/communication/navigation
In Figure 1.1 the frame or chassis on which the body is mounted is
supported by the suspension system. The wheels’ brakes are connected to the
opposite end of the suspension components. The steering and other major
mechanical systems are mounted on one of these components and attached as
necessary through mechanical components to other subsystems.
This basic vehicle configuration was used from the earliest cars through
the late 1960s or 1970s, with some notable exceptions. The increasing
importance of fuel efficiency and government-mandated safety regulations led
to major changes in vehicle design. The body and frame evolved into an
integrated structure to which the power train, suspension, wheels, etc., were
attached.
Once again with a few notable exceptions, most cars had an engine in front
configuration with the drive axle at the rear. While it is an advantage for several
reasons (e.g., crash protection, efficient engine cooling) to have the engine in front,
this location has a disadvantage from a traction standpoint. Because the engine is a

UNDERSTANDING AUTOMOTIVE ELECTRONICS 3