【编者按】 本节我们将对发动机主要部件的名称及功能进行介绍。

Let's look at some key engine parts in more detail.

Spark plug
The spark plug supplies the spark that ignites the air/fuel mixture so that combustion can occur. The spark must happen at just the right moment for things to work properly.

Valves
The intake and exhaust valves open at the proper time to let in air and fuel and to let out exhaust. Note that both valves are closed during compression and combustion so that the combustion chamber is sealed.

Piston
A piston is a cylindrical piece of metal that moves up and down inside the cylinder.

Piston rings
Piston rings provide a sliding seal between the outer edge of the piston and the inner edge of the cylinder. The rings serve two purposes:

They prevent the fuel/air mixture and exhaust in the combustion chamber from leaking into the sump during compression and combustion.
They keep oil in the sump from leaking into the combustion area, where it would be burned and lost.
Most cars that "burn oil" and have to have a quart added every 1,000 miles are burning it because the engine is old and the rings no longer seal things properly.

Connecting rod
The connecting rod connects the piston to the crankshaft. It can rotate at both ends so that its angle can change as the piston moves and the crankshaft rotates.

Crankshaft
The crankshaft turns the piston's up and down motion into circular motion just like a crank on a jack-in-the-box does.

Sump
The sump surrounds the crankshaft. It contains some amount of oil, which collects in the bottom of the sump (the oil pan).

【中文注解】

火花塞
火花塞的主要作用是点燃气缸内的混和气体。

筏门
进气筏与排气筏的作用就是在适当的时候打开，以便让空气及燃气流入或流出。不过在压缩及燃烧冲程过程中，这两个筏门全是关闭的。

活塞
这是一种圆柱状的金属部件，在气缸内上下运动。

活塞环
活塞环是一个滑动的密封垫，位于活塞外缘及气缸内壁之间。

连接杆
边接杆的作用是连接活塞与曲轴。

曲轴
典轴的作用是将活塞的上下运动转化为旋转运动。

油底壳
油底壳包围着曲轴，内含一定量机油，都储集在油箱底部。

【延伸阅读】

*?? 汽车的心脏——发动机

*? 发动机原理及详解之一

*??发动机原理及详解之二

*??发动机原理及详解之三
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