机电工程专业英语 教学课件 ppt 作者 朱晓玲 Lesson 22 Internal Combustion Engine

Lesson 22 Internal Combustion Engine,词汇讲解 课文分析 练习答案,本课教学目标：,掌握内燃机的分类方法； 掌握与内燃机相关的专业词汇； 翻译技巧：信*达*雅,Section ： words and phases,See if you can pronounce these words rightly: exothermic 9eksEJW:mIk adj. 化发热的 petroleum pi5trEuliEm n. 石油 turbocharge t:bEJtFB:dV vt. 用涡轮给(发动机)增压 Pay close attention to the words concerning an internal combustion engine piston rotor connecting rod cylinder,Now please remember the new words and phrases as fast as you can.,Section ： text,At first, read the first paragraph silently in 3 minutes, please.,paragraph :,The internal combustion engine is a heat engine in which the burning of a fuel occurs in a confined space called a combustion chamber. This exothermic reaction of a fuel with an oxidizer creates gases of high temperature and pressure, which are permitted to expand. The defining feature of an internal combustion engine is that useful work is performed by the expanding hot gases acting directly to cause movement, for example by acting on pistons, rotors, or even by pressing on and moving the entire engine itself.,内燃机是一种热机，燃料在其被称为燃烧室的密封空间内燃烧。燃料和氧化剂间的放热反应产生可膨胀的高温高压气体。内燃机的显著特点是能做有用功，即膨胀的受热气体直接作用在物体上并使其运动，如活塞、转子，乃至整个内燃机本身。,Oral English practice :,Whats an internal combustion engine? Say whats you know about an internal combustion engine as much as you can.,Read the second paragraph silently in two minutes, please.,paragraph :,Car engines vary in design, but certain elements are common to all engines and are used for engine classification. Engines can be classified in several ways such as the number of cylinders, the geometry of the block, or type of ignition system used. The two major engine types in use are spark ignition (gasoline engine) and compression ignition (diesel engine) which use different types of fuel. The following are ways engines are classified.,汽车内燃机因设计的不同而不同，但某些元件是所有内燃机所共有的，并用作内燃机的分类依据。内燃机可按气缸的数目、气缸的排列方式和点火系统的类型等方式分类。常用的两大类内燃机是火花点火式（汽油机）和压缩点火式（柴油机）内燃机，他们使用不同种类的燃料。下面是内燃机的分类方法。,Oral English practice :,In how many ways can engines be classified? And what are they?,Flip through the third paragraph in two minutes, please.,paragraph :,Fuel Burned: Fuel burned provides a broad engine classification. Two types of fuel are in general use: gasoline and diesel oil. Gasoline car engines use spark ignition whereas diesel engines use compression ignition (no spark.) Alternate fuels such as liquefied petroleum gas (LP-gas), gasohol (90% gasoline, 10% alcohol), and pure alcohol are used in very limited situations.,按所用燃料分类是使用的较为广泛的一种分类方法。汽油和柴油是使用的最为广泛的两种燃料。汽油机采用火花点火而柴油机采用压缩点火（无火花）。诸如石油液化气、酒精-汽油混合燃料（90汽油，10酒精）和纯酒精等代用燃料使用地较少。,Oral English practice :,How many kinds of fuel can be in use in internal combustion engines according to paragraph 3? And what are they?,Now well come to paragraph four, please read the it silently in 3 minutes,.,paragraph :,Block Geometry: There are four types of engine block geometry: V-type, inline, horizontally opposed and slant. Each refers to the orientation of the cylinders as viewed from the front or back of the engine. A V-type has two angled rows of cylinders, which form a “V.” An inline engine arranges the cylinders vertically in a row. The horizontally opposed engine has the cylinders horizontal and opposing each other. A slant design is one row of angled cylinders forming a half “V.” A slant block allows the hood line to be lower.,气缸有四种排列方式：V型、立式、卧式对置和倾斜布置。每一种方式是指气缸从内燃机的前面或后面看上去的方位。V型是指气缸排成类似V型的两排。立式内燃机的多个气缸垂直排成一排。卧式对置内燃机的气缸水平对置。倾斜式内燃机的气缸排成类似半个V型的一排。倾斜式内燃机的车篷可以设计的更低。,Now browse paragraph five in 3 minutes, please.,paragraph :,Number of Cylinders: The number of cylinders is often used in combination with the engine block geometry (V6, slant four, inline four.) The number of cylinders is an indication of how smooth the car engine will run. An eight-cylinder engine will run smoother than a four-cylinder engine since power strokes occur with greater frequency. The number of cylinders also contributes to power output; more cylinders, more power. However, this is not always a good indicator of power output. A turbocharged, four-cylinder engine can produce more power than a normally aspirated six-cylinder engine.,气缸数目分类法常常与气缸排列方式分类法联合使用（如V型6缸、倾斜型4缸和立式4缸）。气缸的数目可以指示出汽车发动机运行的平稳性。8缸内燃机比4缸内燃机的工作冲程间隔短，故运行更平稳。气缸的数目还与输出功率有关，气缸越多，内燃机输出的功率就越大，但这也不是绝对的。一个涡轮增压4缸发动机有可能比通常的吸气式的6缸发动机输出的功率还大。,Now please have a glance at paragraph six in 2 minutes.,paragraph :,Ignition Type: Two methods for igniting fuel are used, spark ignition and compression ignition. Gasoline car engines use spark ignition whereas diesel engines use compression ignition. This method compresses the air to the point where the resulting rise in temperature causes ignition to occur when diesel fuel is added.,按点火方式可分为两种：火花点火和压缩点火。汽油机使用火花点火，而柴油机使用压缩点火。压缩点火方式是指添加柴油时压缩空气使温度升高到柴油的燃点而使柴油燃烧。,Section ： exercises,Now its time to do the exercises. And please finish them in five minutes.,This is the end for lesson 22. It will be greatly appreciated if you could review lesson 2