Page 189 - 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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Engine systems 173

Figure 2.185 Air supply components

Figure 2.186 Throttle body

included. For fuel injection engines, the system will also include a throttle-body
housing and an air-fl ow meter ( Figs 2.186–2.188 ).
Clean air is required in the engine to prevent particles of dust and grit from
damaging, or blocking, engine and fuel-supply components. Air is fi ltered
through an element in the air cleaner. Most air-cleaner elements are made from Key fact
microporous paper, which allows a good fl ow of air but traps airborne dust. Most air-cleaner elements are made
Other elements have included oiled wire gauze and foam rubber. The air-cleaner from microporous paper, which
housing and the fi lter elements are cleaned, or replaced, at scheduled service allows a good fl ow of air but traps
intervals. airborne dust.
Paper elements are folded to provide a large surface area and long service life.
The element can be wrapped to form a circular element if required. The outside
edges are sealed with an integral, or separate, rubber sealing ring. Air-cleaner
housings have internal ducting to distribute the air over the full surface of the
fi lter ( Fig. 2.189 ). The air fl ow in some fi lter housings is made to swirl so that
airborne dirt is thrown out and falls into a dust trap in the base of the fi lter. The
air fl ow into fl at fi lters is from the underside so that dirt falls out from below,
rather than into the top of, the fi lter.
The inlet manifolds on modern engines are usually of the same length and
diameter to enable all cylinders to be supplied with the same volume of air and