车专业英语Unit-3-Passage-A课件

1、Unit Three Engine Systems Passage ALubrication and Cooling SystemsLubrication systemThe purpose of the engine lubrication system (see Fig.3-1) is to deliver clean en-gine oil at the correct temperature and pressure to every moving part of the engine to reducefriction between the surfaces of the part

2、s which contact each other The major parts of thelubrication system are listed below: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

3、 found on most cars: gear-type and rotor-type oil pumps as shown in Fig.3-2Oil 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 imp

4、ortant 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 engineOil 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 fro

5、m 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 o

6、ff the engine parts It also seals between the cylinder walls and piston rings, improving the engines com-pression.In modern engine designs, two methods of lubrication are combined: pressure lubrication and splash lubrication (see Fig.3-7).Cooling systemThe purposes of the cooling system are to remov

7、e 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 dissipa

8、te 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 in front of the engine compartment, just behind the grill.Radiator fan (see Fig.3-10) is designed to keep the air flow goin

9、g through the radiator while the car is going or it stops with the engine running Usually, two fans are mounted on the back of the radiator.Water pump (see Fig.3-11) is a simple device that can keep the coolant flowing as long as the engine is running It is driven by the engine through the timing be

10、lt.Pressure cap (see Fig.3-12) is designed to maintain pressure in the cooling system If the pressure rises up higher than the set pressure point, the cap with a spring loaded valve will release the pressure to the expansion tank to prevent loss of coolant and return the coolant to the radiator when

11、 it cools down.Expansion tank (see Fig.3-13) is used to fill the coolant In addition, when the coolant in the engine expands and is forced out of the radiator, it overflows into the expansion tank When the engine cools down and coolant contracts, the vacuum draws the coolant back into the radiator i

12、n order to make it always completely full.Thermostat (see Fig.3-14) is simply a valve that measures the temperature of the coolant The thermostat helps the engine reach the operating temperature sooner by keeping the coolant from flowing to the radiator As the engine reaches operating temperature, t

13、he thermostat opens and allows the coolant to flow to the radiator through the upper hose.Coolant or antifreeze performs two functions: it keeps the radiator fluid from freezing in wintry conditions and keeps the engine from overheating in warm weatherNew Words and Expressionslubrication lubrikein n

14、 润滑friction frikn n 摩擦contact kntkt vt 使接触task t: sk n 工作, 任务circulate skjleit vt 使循环, 使流通particle ptikl n 颗粒, 粒子remove rimuv vt 删除, 除去crud krd n 渣滓; 杂质media midi n 媒质mount maunt vt 安装deposit dipzit n 沉积物excess ikses adj 过量; 过分; 过度efficient ififnt adj 有效率的, 效率高的coolant kulnt n 冷却液absorb bsb vt 吸收tub

15、e tjub n 管release rilis vt 释放overflow uvflu vt 溢流contract kntrkt vi 收缩vacuum vkjum n 真空antifreeze ntifriz n 防冻液freeze friz vt 结冰wintry wintri adj 寒冷的, 冬天的overheat uvhit vi 过热moving part运转部件, 运动件take in吸收filter media过滤介质serve as作为; 充当at rest静止warm up热机be designed to目的是; 设计用于spring loaded valve弹簧加载阀force out of把压出来Common Automobile Termsradiator reidieit n 散热器grill gril n 格栅thermostat mstt n 节温器lubrication sy