汽车专业英语课件与汽车专业英语读译教程2版配套2U2TA.ppt

 UNIT 2 ENGINE MECHANICAL TEXT A Operation, Main Components and Classification of the Engine  UNIT 2 ENGINE MECHANICAL TEXT A Operation, Main Components and Classification of the Engine  ? Principle of Operation  ? Main Engine Components  ? Engine Classification 本次课学习目标 掌握发动机主要部件的英文名称 掌握各中发动机的英文名称 掌握常用术语（phrases and expressions） 了解相关术语（related terms） 较熟练翻译与发动机工作原理相关的英文文章 NEW WORDS oscillate [?sileit]v.振荡，振动，波动，动摇 bearing [b??ri?]n.轴承 journal[??:n?l]n.轴颈 throw [?rou]n. v.投掷，扔；n.投掷距离，偏心距离，摆幅；（pl.）曲柄 attach [?t?t∫]v.附着，连接，固定（to） reciprocating [risipr?keiti?]a.往复的 mount [mɑunt]v.安装，固定；n.安装件，支架，机座 rim [rim]n.边缘，轮缘，轮辋，齿圈 heat-resistant [hi:trizist?nt ]a.耐热的 clearance [kli?r?ns]n.间隙 lifter [lift?]n.挺杆 insert bearing 镶入式轴承 valve seat 气门座 valve guide 气门导管 valve train 气门机构，气门组 hydraulic valve lifter 液力挺杆 Fig. 2-1 The operation of a four-stroke-cycle gasoline engine The first stroke in your engine is called the intake stroke. Instead of opening the intake valve after you have drawn the piston down, you will find it better to open the intake valve as the piston starts down [1]. This allows the air to draw fuel in the entire time the piston is moving down. Remember, the intake stroke starts with the piston at the top of the cylinder (intake valve open and exhaust valve closed) and stops with the piston at the bottom of its travel [2]. This requires one-half turn of the crankshaft. As the crankshaft continues to move, the piston is forced up through the cylinder. If you keep both valves closed, the fuel mixture will be squeezed, or compressed, as the piston reaches the top. This is called the compression stroke. It, too, requires a half turn of the crankshaft. The compression stroke serves to break up the fuel into even smaller particles. This happens due to the sudden swirling and churning of the mixture as it is compressed. When the air-fuel mixture is subjected to a sudden sharp compression fo