automobile engines

　　Most automobile engines are internal combustion,reciprocating 4-strike gasonline engines, but other types have been used,including the diesel,the rotary(wankel),the 2-stroke,and the stratified charge.

　　Reciprocating means "up and down"or "back and forth".It is the up and down action of a pistion in the cylinder that produces power in a reciprocating engine .Almost all engines of this type are built upon a cylinder block,or engine block is an iron or aluminum casting that contains engine cylinders and passages called water jackets for coolant top of the block is covered with the cylinder head,which forms the combustion bottom of the block is covered with an oil pan or oil sump.

　　Power is produced by the linear motion of a piston in a r,this linear motion must be changed into rotary motion to turn the wheels of cars or piston is attached to the top of a connecting rod by a pin,called a piston pin or wrist bottom of the connecting rod is attached to the connecting rod transmits the up-and-down motion of the piston to the crankshaft,which changes it into rotary connecting rod is mounted on the crankshaft with large bearings called rod r bearings,called main bearings,similar bearings,called main bearings,are used to mount the crankshaft in the block.

　　大多数汽车引擎采用往复式四冲程汽油内燃机，但也有其它类型的引擎被采用，包括柴油机，汪克尔发动机，二冲程发动机以及层状充气发动机。

　　往复运动意思就是“上下”或“前后”运动。这是一个活塞在缸体内做上下方向的运动，在往复式引擎中，也就是这个运动提供了动力。几乎所有这种类型的引擎都是做在一个缸体或者说发动机体之上的。这个基体是一个铁铸件或铝铸件，缸体内包含了发动机活塞缸和一个叫做水套的用做循环冷却的通道，缸体的顶部安装有汽缸盖，汽缸盖的内部结构形成燃烧室。缸体的底部安装有一个油盘或油底壳。

　　动力由气缸内的一个活塞作直线运动产生。然而，这个直线运动需要转换成旋转运动才能带动车辆的轮子转动。这个活塞被一个叫活塞销或轴颈销的销子连接在连杆的上部。连杆的底部被连接在曲轴上。连杆把活塞的上下运动传递给曲轴转变成旋转运动。连杆通过一个大的叫做杆轴承的轴承（其实就是滑动轴承，分成两个半圆轴瓦）安装在曲轴上。同样的轴承叫主轴承用来将曲轴安装在发动机体上。