车专业英语Unit-2-Passage-A课件

1、Unit TwoEngine ConstructionPassage A Crank Mechanism and Its Main ComponentsCrank mechanism is one of the major motion mechanisms of the engine Its function is to transform the reciprocating movement of pistons into rotary movement of the crankshaft, offering torque to make the drive wheels turn (se

2、e Fig.2-1). Crank mechanism is divided into 3 groups: block group; piston and connecting-rod group; and crankshaft and flywheel groupThe block group contains the following main components (see Fig. 2-2):Cylinder head is bolted to the top of the cylinder block with a gasket in between sealing the blo

3、ck and forming the combustion chambers with the cylinders Cylinder head holds camshafts, valves, spark plugs and injectorsOil panis at the bottom of the cylinder block It is a container for storage of engine oilPiston and connecting-rod group has some main components as follows ( see Fig.2-3):Piston

4、is a cylindrical shaped hollow part made of aluminum alloy It can be divided into three parts: crown, ring groove and skirt (see Fig.2-4). Its reciprocating movements in the cylinder transform the energy of the expanding gases into mechanical energyPiston rings are inserted in the ring grooves on th

5、e top of the piston Most pistons have three rings: the top two are compression rings and the lower ring is an oil ring They function as sealing between the piston and cylinder wall, lubricating, heat transferring and piston supporting in the cylinderConnecting rod connects the piston to the cranksha

6、ft It has a small end and a big end The small end attaches to the piston with the piston pin and the big end connects to the crank pin of the crankshaftCrankshaft and flywheel group includes thefollowing components (see Fig. 2-5):Crankshaftis one of the most important parts in the engine It is held

7、in the crankcase in the cylinder block and converts the reciprocating motion of the pistons into a rotary motion for the drive wheels In a 4-cylinder engine, the crankshaft usually has three main journals and four crank pins attached to the big ends of the connecting rods Every crankshaft has counte

8、r weights whose purpose is to balance the weight of the connecting rods Its front end is used to drive the valve train, water pump and cooling fan, and its rear end is used to install the flywheelFlywheel is a rotating disk located on one end of the crankshaft It has a ring gear around the disk Its

9、purposes are to reduce vibration caused by the power stroke through its inertia, and to start the engine when the starter meshes with itNew Words and Expressionsmechanism meknizm n 机制; 机械装置component kmpunnt n 部件, 零件transform trnsfm vt 改变, 转换torque tk n 扭矩, 转矩aluminum lummm n 铝lubricant lubriknt n 润滑

10、剂; 润滑油bolt bult n 螺栓 vt 用螺栓固定seal sil vt 密封container kntein n 容器storage strid n 存储hollow hlu adj 空的, 空腹的skirt skt n 裙部attach tt vi 连接, 固定reduce ridjus vt 减少, 降低inertia in n 惯性cast iron铸铁, 生铁cast aluminum铸铝aluminum alloy铝合金ring groove活塞环槽, 环槽mechanical energy机械能mesh with(齿轮) 啮合Common Automobile Termscrankcase krkkeis n 曲轴箱gasket gskit n 气缸垫, 垫圈camshaft kmft n 凸轮轴injector indekt n 喷油器flywheel flaiwil n 飞轮crank mechanism曲柄连杆机构block group机体组cylinder block气缸体water jacket水套, 冷却管lubricant passage润滑油道oil pan油底壳engine oil机油piston and connecting rod group活塞连杆组piston ring活塞环com