新编汽车专业英语第3版黄汽驰电子课件Unit3PassageA.pptxVIP

Unit Three　 Engine Systems　;Passage ALubrication and Cooling Systems; Oil pump is the key part in the lubrication system． Its task is to produce the pressure high enough to draw the engine oil from the oil pan and circulate it throughout the sys-tem． Two types of the oil pumps are often found on most cars: gear-type and rotor-type oil pumps as shown in Fig.3-2．;Oil screen (see Fig.3-3) is located at the bottom of the oil pan． It is connected to the oil pump． Its job is to collect any large particles of dirt before the engine oil entering the pump.;Oil filter (see Fig.3-4) is a very important part in this system． It takes in dirty oil, removes crud and keeps it trapped in the filter media, and returns the clean oil back to the engine．;Oil pan (see Fig.3-5) is a container mounted at the bottom of the crankcase which serves as engine oil storage． It collects the oil as it flows down from sides of the crankcase when the engine is at rest.;Engine oil (see Fig.3-6) has several important jobs in the engine． It lubricates the moving engine components with less friction． The circulating oil cools the engine by carry-ing heat away from the hot engine components． It cleans dirt and deposits off the engine parts． It also seals between the cylinder walls and piston rings, improving the engine’s com-pression.;In modern engine designs, two methods of lubrication are combined: pressure lubrication and splash lubrication (see Fig.3-7).;Cooling system The purposes of the cooling system are to remove excess heat from the engine, to keep the engine operating at its most efficient temperature, and to warm up the engine to the efficient temperature as soon as possible after starting (see Fig.3-8). The major parts of the cooling system are listed below:;Radiator (see Fig.3-9) is designed to dissipate the heat which the coolant has absorbed from the engine． It consists of radiator core, water-carrying tubes, an inlet tank and an outlet tank． Usually, the radiator is mounted