Page 192 - 05. Subyek Teknik Mesin - Automobile Mechanical and Electrical Systems Automotive Technology Vehicle Maintenance and Repair (Vehicle Maintenance Repr Nv2) by Tom Denton

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176 Automobile mechanical and electrical systems

Figure 2.192 Warm-air control (vacuum type)

AB

Figure 2.193 Inlet tracts change at different speeds: A: long tract, B: short tract

The air supply to each cylinder passes through equal length and diameter tubes
of the inlet manifolds. Feeding the manifold tubes is a plenum chamber, which
holds a large volume of air so that each intake tube receives an equal air supply.
The air fl ow is made to swirl in the intake tubes, and careful design of the shape
and direction of the tubes is required to make this happen. Another factor
affecting the swirl is the volume and speed of the air fl ow.
Some engines have a dual-intake system that responds to low and high
engine speeds ( Fig. 2.193 ). These systems have valves that open at higher
engine speeds to balance the pressure in the two intake manifolds, or open
to enable a secondary air supply to provide an adequate air fl ow for the higher
engine speed. These systems have been developed to meet the changing air
fl ow and swirl characteristics occurring with increases in air mass and speed.

2.4.4 Exhaust systems

The exhaust system has to carry the exhaust gases out of the engine to a safe
position on the vehicle, silence the exhaust sound and cool the exhaust gases.