汽车专业英语-2-AUTOMOTIVEENGINE讲解课件

1、Chapter 2 AUTOMOTIVE ENGINE 背景知识 发动机最早诞生在英国，所以，发动机的概念也源于英语，它的本义是指那种“产生动力的机械装置”。随着科技的进步，人们不断地研制出不同用途多种类型的发动机，如：活塞式，转子式，涡轮喷气式，涡轮风扇式等。但是，不管哪种发动机，它的基本前提都是要以某种燃料燃烧来产生动力。所以，以电为能量来源的电动机，不属于发动机的范畴。回顾发动机产生和发展的历史，它经历了外燃机和内燃机两个发展阶段。 Chapter 2 AUTOMOTIVE ENGINE 背景知识 外燃机，就是说它的燃料在发动机的外部燃烧，发动机将这种燃烧产生的热能转化成动能，瓦特发明的

2、蒸汽机就是一种典型的外燃机，当大量的煤燃烧产生热能把水加热成大量的水蒸汽时，高压便产生了，然后这种高压又推动机械做功，从而完成了热能向动能的转变。 蒸汽机 steam engine（steamer）Watt invented the steam engine. 瓦特发明了蒸汽机。 Chapter 2 AUTOMOTIVE ENGINE 背景知识 内燃机与外燃机的最大不同在于它的燃料在其内部燃烧。内燃机的种类十分繁多，我们常见的汽油机、柴油机是典型的内燃机。我们不常见的火箭发动机和飞机上装配的喷气式发动机也属于内燃机。不过，由于动力输出方式不同，前两者和后两者又存在着巨大的差异。一般地，在地面上

3、使用的多是前者，在空中使用的多是后者。 当然有些汽车制造者出于创造世界汽车车速新纪录的目的，也在汽车上装用过喷气式发动机，但这总是很特殊的例子，并不存在批量生产的适用性。 Internal combustion内燃机作为汽车.拖拉机.摩托车.工程机械.船舶.航空.农业.林业.军队.等各行各业的动力装置，应用极为广泛， Chapter 2 AUTOMOTIVE ENGINE New Wordslongitudinal lnditju:dinl adj. 纵向的，经度的transverse trnsv:s adj. 横向的，横断的reciprocate rsprket v. 往复，来回spin s

4、pin v. 旋转；n旋转piston pistn n. 活塞 ignite inait v. 点火，点燃rub rb v. 摩擦，擦quart kw:t n. 夸脱(容量单位)reservoir rezvw: n. 油箱mechanical miknikl adj. 机械的，机械制的，机械似的，呆板的enclosed inkluzd adj. 被附上的gallon ln n. 加仑stroke struk n. 冲程，行程Chapter 2 AUTOMOTIVE ENGINE New Wordsrub rb v. 摩擦，擦camshaft km:ft n. 凸轮轴combustion kmb

5、stn n. 燃烧，着火disengaged dsn ged d adj. 脱开的，脱离啮合的flywheel flaiwi:l n. 飞轮，惯性轮，储能轮 PHRASES AND EXPRESSIONSinternal-combustion engine 内燃机diesel-fuel 柴油机燃料，柴油LPG = Liquefied Petroleum Gas 液化石油气体CNG = Compressed natural gas 压缩天然气spark ignition 火花点火 PHRASES AND EXPRESSIONScompression ignition 压缩点火spark plug

6、 火花塞gas-turbine engine 燃气涡轮发动机steam engine 蒸汽机Stirling engine 斯特灵发动机lubricating system 润滑系统oil pan 油底壳oil pump 机油泵exhaust system 排气系统emission-control system 排放控制系统Chapter 2 AUTOMOTIVE ENGINE PHRASES AND EXPRESSIONSenergy conversion 能量转换air/fuel ratio 空燃比connecting rod 连杆TDC = Top Dead Center 上止点BDC

7、= Bottom Dead Center 下止点intake stroke 进气冲程compression stroke 压缩冲程power stroke 作功冲程exhaust stroke 排气冲程compression ratio 压缩率，压缩比Chapter 2 AUTOMOTIVE ENGINE The purpose of an automotive engine is to supply the power needed to move the vehicle. The engine produces this power by burning fuel inside it. B

8、ecause the engine burns fuel inside, or internally, the engine is known as an internal combustion engine (ICE) .Chapter 2 AUTOMOTIVE ENGINE2.1 Purpose and Locations of Engines译文：汽车发动机的功用是汽车行驶提供必需的动力。发动机通过它内部的燃料燃烧来产生动力。由于发动机在其内部燃烧燃料，所以发动机被称作内燃机。Engines may be fueled by gasoline, propane （LPG-liquefie

9、d petroleum gas） , or diesel fuel. Compressed natural gas （CNG） may also be used in some vehicles.译文：发动机燃料可以是汽油、丙烷（液化石油汽体）或柴油。压缩天燃气也可以用在一些车辆上。be fueled by 通过得到燃料Most automotive engines are located at the front of the vehicle. Many engines drive the rear wheels. This requires a long drive shaft exten

10、ding form the front wheels to the rear wheels. Other engines drive the front wheels. In the rear-wheel-drive arrangement, the engine sits longitudinally. Its long dimension is from front to back.译文：大多数汽车发动机位于汽车前方。许多发动机由后轮驱动。这需要一根长传动轴从前轮延伸到后轮。其它发动机由前轮驱动。在后轮驱动布置中，发动机纵向放置。它前后尺寸最长。In the front-wheel-dri

11、ve arrangement, the engine sits crosswise, transversely. With either arrangement, the power is carried to the drive wheels （rear or front）by gears and shafts.译文：在前轮驱动布置中，发动机横向放置。不管哪种放置方式，动力都是通过齿轮和轴传递到驱动轮。Some cars have the engine mounted in back of the front seat. This is called a mid-engine arrange

12、ment. Other cars have been built with the engine mounted at the rear, in back of rear seat. The Volkswagen beetle is an example of rear.译文：一些轿车把发动机安装在前排座位的后面，这称为中置发动机布置。其它轿车发动机安装在车的尾部，也就是后排座的后面。比如：大众汽车甲壳虫就是采用这种发动机后置布置。 Various kinds of engines are used in automotive vehicles. The two major types are

13、:1. The piston engine in which pistons move up and down, or reciprocate, in the engine cylinders. This is the engine used in all cars today, except for some models of Mazda.Chapter 2 AUTOMOTIVE ENGINE2.2 Engine Types译文：机动车辆上采用各种各样的发动机，其两种主要类型为：1、活塞发动机，活塞在其气缸内上下或往复运动。这就是现今轿车所采用的发动机形式，除了马自达的一些型号发动机。cy

14、linderpistonPiston pinConnecting rodcrankshaftOil pipeIntake valveExhaust valve Timing gearOil pump2. The Wankel rotary engine in which rotors rotate, or spin. The Mazda Motor Corporation of Japan is the major manufacturer of this engine.译文：汪克尔转子发动机，由其转子回转。日本马自达发动机公司是这类发动机的主要生产商。There are two types

15、of piston engines-spark ignition （SI） and compression ignition（CI） . Spark-ignition engines use an electric ignition system with spark plugs. Electric sparks at the spark plugs ignite, or set fire, the fuel in the engine cylinders. 译文：有两种类型的活塞发动机：火花点火和压缩点火。火花点火发动机采用带有火花塞的电子点火系统。火花塞的电火花点燃发动机气缸中的燃料。Th

16、e combustion of the fuel makes the engine run and produce power. This is the type of engine used in most produce power. This is the type of engine used in most automotive vehicles.译文：燃料燃烧使发动机运转并产生动力。这是在大多数产生动力的发动机所采用的形式，这种类型的发动机在大部分机动车辆上使用。The compression-ignition engine the diesel uses the heat of

17、compression to ignite the fuel. When air is compressed, it gets very hot. In the diesel engine, the air is compressed so much that its temperature goes up to 1,000 degrees Fahrenheit （538 degrees Celsius） or higher. 译文：压缩点火发动机，柴油机使用压缩产生的热量来点燃燃料。当空气被压缩时，会变得非常热。柴油机内空气压缩温度可过1000华氏以上（538摄氏度）。一般情况下,柴油的燃点

18、220 汽油的燃点427The diesel fuel is sprayed into this very hot air and is ignited by the heat. Some automobiles have diesel engines. Many heavy-duty trucks and buses are powered by diesel engines.译文：然后柴油被喷射到这种热空气中，并被这种热度点燃。一些汽车上采用柴油机。大多重型卡车和客车由柴油机提供动力。There are other engines still in the experimental sta

19、ge that might someday become important. These include gas-turbine engines, steam engines, Stirling engines, and electric motors.译文：还有一些其它的发动机仍处于实验阶段，总有一天会变得重要。它们包括燃气涡轮发动机、蒸汽机、斯特林（热气体）发动机和电动机。 A spark-ignition engine requires four basic systems to run. Diesel engines require three of these systems. T

20、hey are fuel system, ignition system（except diesel） , lubricating system and cooling system. Each performs a basic job in making the engine run. These are described briefly below.Chapter 2 AUTOMOTIVE ENGINE2.3 Basic Engine Systems译文：火花点火发动机运转需要4个基本系统。柴油发动机需要其中的3个。它们是燃料系统，点火系统（除了柴油机），润滑系统和冷却系统。其每个系统在

21、使发动机运转时完成一个基本工作。简要介绍如下：2.3.1 Fuel SystemsThe fuel system supplies gasoline or diesel fuel to the engine. This fuel is mixed with air to make a combustible mixture （a mixture that will burn）. Each cylinder is repeatedly filled with the mixture. 译文：燃料系统给发动机提供汽油或柴油燃料。燃料与空气混合形成可燃混合气（一种会燃烧的混合物）。气缸被反复填充这种

22、混合气体。Then, the mixture is ignited and burned, producing high pressure. The high pressure makes the pistons move （or rotors spin） . This turns shafts that rotate the wheels, causing the vehicle to move.译文：然后被点燃、燃烧，产生高压，推动活塞运动（或转子旋转）。这使车轴带到车轮旋转，从而使车辆移动。2.3.2 Ignition systemEvery time the fuel system d

23、elivers air/fuel mixture to a cylinder, the ignition system follows up by delivering an electric spark. This ignites the mixture which creates the high pressure that moves the pistons and turns the car wheels. The action is repeated many times each second while the engine is running.译文：每当燃料系统传送可燃混合气

24、给气缸，点火系统随后会产生电火花来点燃混合气，从而产生高压，使活塞运动和车轮运转。当发动机运转时，每秒钟这个动作重复多次。The ignition system takes the low voltage, of the battery and builds it up to a very high voltage: as high as 47,000 volts in some systems. This high voltage jumps the gaps in the spark plugs, producing the sparks that ignite the air/fuel

25、mixture in the engine cylinders.译文：点火系统把蓄电池的低压增到高压，在一些系统中可达到47000伏。高压击穿火花塞（两电极之间）间隙，产生电火花，点燃发动机气缸内的可燃混合气。2.3.3 Lubricating systemThe engine has many moving metal parts. If metal parts rub against each other, they will wear rapidly. To prevent this, engines have lubricating oil. The oil gets between

26、the metal parts so they slide on the oil, and not on each other.译文：发动机有许多运动金属部件。如果金属部件之间相互磨擦，会加速磨损。为防止这样，发动机带有润滑油。润滑油充斥在金属部件之间，从而使它们在油面上滑动，而不是在其表面。The lubricating system has an oil pan at the bottom of the engine which holds several quarts （liters）of oil. An oil pump, driven by the engine, sends oil

27、 from this reservoir through the engine. After circulating through the engine, the oil drops back down into the oil pan. The oil pump continues to circulate the oil as long as the engine is running.译文：润滑系统油底壳位于发动机的底部，它可保存几夸脱（升）的润滑油。油泵由发动机驱动把润滑油从油底壳送到发动机各个部件，润滑油在发动机内循环后，回落到油底壳中。只要发动机不断运转，油泵就会连续循环润滑油。

28、夸脱(容量单位=1/4 加仑, 约1.14升)2.3.4 Cooling systemWhere there is fire（combustion）, there is heat. Burning of the air/fuel mixture raises the temperature inside the engine cylinders several thousand degrees. 译文：有火（燃烧）的地方，就会有热。可燃混合气的燃烧会把发动机气缸内的温度提升到几千摄氏度。Some of this heat produces the high pressure that move

29、s the pistons to produce power. Some of the heat leaves the cylinders with the exhaust gas. The exhaust gas is what is left after the air/fuel mixture burns. It is cleared out of the cylinders after combustion is complete.译文：其中一部分热量产生高压推动活塞运动来产生动力。另外一部分热量随着废气排出气缸。废气是指可燃混合气燃烧后残留的气体。它在燃烧完成后被排出气缸。 Some

30、 of the heat is removed by the circulating oil. After the hot oil drops down into the oil pan, the oil gives up some of this heat to the air passing under the oil pan. The rest of the heat is removed by the cooling system.译文：还有一部分热量由循环润滑油带走。灼热的润滑油落到油底壳后，会把部分热量传给通过油底壳下方的空气。其余热量由冷却系散发。2.3.5 Other engi

31、ne systemsAn engine will run with the four basic systems described abovefuel, ignition, lubricating, and cooling. However, three other related systems are also necessary. These are the exhaust system, the emission-control system, and the starting system.译文：发动机运转需要上述4个基本系统燃料、点火、润滑和冷却。但是，还有另外三个相关系统也是必

32、需的。它们是排放系统、废气处理（排气净化）系统和起动系统。The exhaust system reduces the noise of the burned gases leaving the engine cylinders and carries these exhaust gases safely away from the people in the car. The emission-control system is required by law to reduce the air pollution the engine could produce. 译文：排放系统功能，一方

33、面减小燃烧废气排出气缸时所产生的噪声，另一方面把这些废气从车中乘客身边安全带走。废气处理（排放控制）系统是法规所要求的用来降低发动机所产生的空气污染。The starting system is needed to crank the engine. A battery provides the electric power to operate the starting motor and the ignition system during cranking.译文：起动系统用来转动发动机曲轴。蓄电池在起动时为开动起动机和点火系统提供电力。 The internal combustion e

34、ngine is a device used to convert the chemical energy of the fuel （gasoline or diesel fuel） into heat energy, and then to convert this heat energy into usable mechanical energy. Chapter 2 AUTOMOTIVE ENGINE2.4 Energy Conversion译文：内燃机是一种把（汽油或柴油）燃料的化学能转变成热能，再转换成可利用的机械能的装置。This is achieved by combining

35、the appropriate amounts of air and fuel, and burning the mixture in an enclosed cylinder at a controlled rate. A movable piston in the cylinder is forced down by the expanding gases of combustion.译文：这通过混合适量的空气和燃料，并在密闭的汽缸中按照控制速度燃烧来实现。气缸中活塞由燃烧气体膨胀作功来压下。An average air/fuel ratio for good combustion is

36、about 15 parts of air to 1 part of fuel by weight. This means that for every gallon of gasoline burned, the oxygen is about 9,000 to 10,000 gallons of air is required. Air is about 21% oxygen and 78% nitrogen.译文：燃烧良好的空燃比，按质量平均大约是15：1。这意味着每加仑汽油完全燃烧所需的空气质量大约在9000到10000加仑。空气中氧气成份点21%，氮气占78%。Diesel engi

37、nes operate on a much wider air/fuel ratio, since air intake is not regulated on most diesels. Ratios may range from about 20:1 to about 100:1. The fact, plus the high compression of the diesel, makes it a very fuel efficient engine.译文：因为进气量在大多数内柴油机上不规则的，柴油机有更宽的空燃比。其范围大约在20：1到100：1之间。实际上，加上柴油机的高压缩比，

38、使其成为极其节约燃油的发动机。fuel efficient节约燃油的，燃油经济性高的The movable piston in the cylinder is connected to the top of a connecting rod. The bottom of the connecting rod is attached to the offset portion of a crankshaft. As the piston is force down, this force is transferred to the crankshaft, causing the cranksha

39、ft to rotate. 译文：气缸活塞与连杆上端相连。连杆底部则连到曲轴的偏心部。当活塞被压下时，驱动力被传递到曲轴，并带动曲轴旋转。The reciprocating （back and forth or up and down） movement of the piston is converted to rotary （turning） motion of the crankshaft, which supplies the power to drive the vehicle.译文：活塞的往复运动转化成曲轴的旋转运动，从而为驱动车辆提供动力。The efficiency of th

40、e internal combustion, reciprocating piston engine in converting the potential energy in fuel into mechanical energy is only about 33 %. Of the available heat energy in the fuel, about one-third is lost through the exhaust system and one-third is absorbed and dissipated by the cooling system. Of the

41、 remaining one-third, about one-half is lost through available at the vehicles drive wheels.译文：活塞发动机在转化燃料的势能为机械能时的效率大约只有33%。对于燃料的可用热能，大概有1/3损失在排放系统中，另外1/3被冷却系统吸收和散发。在剩余的1/3中，约有一半完全利用在车辆的驱动轮上。The overall efficiency of the diesel engine is considerably higher than that of the gasoline engine. The reas

42、ons for this are: the higher compression ratio, the higher air/fuel ratio, and the higher heat value of the fuel. The useful power developed at the drive wheels by a diesel engine is about 25% as compared to 15% by a gasoline engine.译文：柴油机的总效率明显高于汽油机。原因在于柴油机的高压缩比，高空燃比和柴油的高热值。柴油机传递到车轮的有效功率大约在25%，而汽油机

43、只有15%。 The movement of the piston from its uppermost position （TDC, top dead center）to its lowest position （BDC, bottom dead center） is called a stroke. Most automobile engines operate on the four stroke-cycle principle. Chapter 2 AUTOMOTIVE ENGINE2.4 Four-Stroke-Cycle Gasoline Engine Operation译文：从活

44、塞的最上端（上止点）到它的最下端（下止点）的运动过程称为一个行程。大多数汽车发动机根据四冲程原理工作。A series of events involving four strokes of the piston completes one cycle. Figure 2-1. These events are: （1） the intake stroke, （2） the compression stroke, （3） the power stroke, and （4） the exhaust stroke. Two revolutions of the crankshaft and one

45、 revolution of the camshaft are required to complete one cycle.译文：四个活塞行程完成一个工作周期。这4个行程是进气行程，压缩行程，作功行程和排气行程。同时，需要曲轴转动两圈，凸轮轴转动一圈。On the intake stroke the piston is pulled down in the cylinder by the crankshaft and connecting rod. During this time the intake valve is held open by the camshaft. Since th

46、e piston has moved down in the cylinder, creating a low-pressure area（vacuum）, atmospheric pressure forces a mixture of air and fuel past the intake valve into the cylinder. 译文：在进气行程中，活塞在气缸中被曲轴和连杆拉下。这时，进气门被凸轮轴开启。因为活塞在气缸中向下移动，产生一个低压区（真空），大气压将可燃混合气通过进气门压入气缸。Atmospheric pressure is approximately 14.7 p

47、ounds per square inch （about 101.35 kilopascals） at sea level. Pressure in the cylinder during the intake stroke is considerably less than this. The pressure difference is the force that causes the air/fuel mixture to flow into the cylinder, since a liquid or a gas （vapor） will always flow from a hi

48、gh-pressure to a low-pressure area.译文：大气压在海平面上大约为14.7磅/平方英寸(101.35千帕)。进气行程中气缸内压力远小于大气压力。因为液体或气体（蒸汽）总是从高压区流向低压区，所以这个压力差促使可燃混合气注入汽缸。As the piston is moved up by the crankshaft from BDC, the intake valve closes. The air/fuel mixture is trapped in the cylinder above the piston. Further piston travel com

49、presses the air/fuel mixture to approximately one-eighth of its original volume （approximately 8: 1 compression ratio） when the piston has reached TDC. This completes the compression stroke.译文：当活塞曲轴带动从下止点向上移时，进气门关闭。可燃混合气封在气缸内活塞的上方。当活塞到达上止点时，可燃混合气体积由活塞运动压缩至其原来体积的约1/8（8:1的压缩比）。这就完成了压缩行程。When the pisto

50、n is at or near TDC, the air/fuel mixture is ignited. The burning of the air/fuel mixture （combustion） takes place at a controlled rate. Expansion of the burning mixture causes a rapid rise in pressure. This increased pressure forces the piston down on the power stroke, causing the crankshaft to rot

51、ate.译文：当活塞移动到上止点附近时，可燃混合气被点燃。混合物的燃烧按照控制速度进行。燃烧气体体积膨胀使（气缸内）压力迅速上升。在此作功行程中，气体增压推动活塞向下移动，带动曲轴旋转。At the end of the power stroke the camshaft opens the exhaust valve, and the exhaust stroke begins. Remaining pressure in the cylinder, and upward movement of piston, force the exhaust gases out of the cylin

52、der. At the end of the exhaust stroke, the exhaust valve closes and the intake valve opens, repeating the entire cycle of events over and over again.译文：在作功行程结束时，凸轮轴打开排气门，进入排气行程。气缸中剩余压力和活塞的向上移动把废气排出气缸。排气行程结束时，排气门关闭，进气门打开，反复不断重复整个冲程循环周期。To start the engine, some method of cranking the engine is requir

53、ed to turn the crankshaft and cause piston movement. This is done by the starter motor when the ignition key is in the start position. 译文：为了起动发动机，需要一些起动方法来转动发动机曲轴，使活塞（上下）运动。这在点火开关处于起动位置时由起动机来实现。When sufficient air/fuel mixture has entered the cylinders and is ignited, the power strokes create enough

54、 energy to continue crankshaft rotation. At the point, the ignition key is released to the run position and the starter is disengaged.译文：当足量的可燃混合气进入气缸并且被点燃，作功行程能产生足够的热量来继续曲轴旋转，此时点火开关释放至运行位置，起动机解除。Sufficient energy is stored in the flywheel and other rotating parts on the power stroke to move the piston and related parts through the other three strokes （exhaust, intake, and compression）. The amount of air/fuel mixture allowed to enter the cylinder determines the power and speed developed by the engine.