内燃机专业英语教案.doc

内燃机专业英语自编讲义部分：一、教学内容：在该部分内容中主要讲述内燃机、汽油发动机、柴油发动机等的相关知识。包括：1. Engine Classification and Overall Mechanics，发动机的分类和总体结构；2. Four-stage-engine Operation，四行程发动机工作过程；3. Two-stage-engine Operation，二行程发动机工作过程；4. Diesel Engine Operating Features，柴油发动机工作特点；5. Engine Cylinder Block Crankcase，发动机气缸体 曲轴箱；6. Piston Connecting Rod，活塞 连杆；7.Crankshaft Flywheel，曲轴 飞轮；8.Valves and Vales Train，气门与气门传动组；9. Engine Fuel System，发动机燃油系统；10. Engine Lubricating System，发动机润滑系统；11. Engine Cooling System，发动机冷却系统；12. Engine Ignition System，发动机点火系统；13. Engine Starting System，发动机起动系统；14. Locomotives，机车；15. Diesel Traction，内燃牵引。二、教学时数：共占用18学时。1. Engine Classification and Overall Mechanics（1学时）发动机的分类和总体结构2. Four-stage-engine Operation（1学时）四行程发动机工作过程3. Two-stage-engine Operation（1学时）二行程发动机工作过程4. Diesel Engine Operating Features（1学时）柴油发动机工作特点5. Engine Cylinder Block Crankcase（1学时）发动机气缸体 曲轴箱6. Piston Connecting Rod（1学时）活塞 连杆7. Crankshaft Flywheel（1学时）曲轴 飞轮8. Valves and Vales Train（1学时）气门与气门传动组9. Engine Fuel System（1学时）发动机燃油系统10.Engine Lubricating System（1学时）发动机润滑系统11. Engine Cooling System（1学时）发动机冷却系统12. Engine Ignition System（1学时）发动机点火系统13. Engine Starting System（1学时）发动机起动系统14. Locomotives（2学时）机车15. Diesel Traction（3学时）内燃牵引三、教学难点与重点：重点内容有：1. Engine Classification and Overall Mechanics，发动机的分类和总体结构；2. Four-stage-engine Operation，四行程发动机工作过程；4. Diesel Engine Operating Features，柴油发动机工作特点；5. Engine Cylinder Block Crankcase，发动机气缸体 曲轴箱；7.Crankshaft Flywheel，曲轴 飞轮；8.Valves and Vales Train，气门与气门传动组；9. Engine Fuel System，发动机燃油系统；10. Engine Lubricating System，发动机润滑系统；11. Engine Cooling System，发动机冷却系统；13. Engine Starting System，发动机起动系统；14. Locomotives，机车；15. Diesel Traction，内燃牵引。四、作业三篇翻译621. Engine Classification and Overall Mechanics发动机的分类和总体结构The automobile engines can be classified according to: 1. number of cylinders; 2. arrangement of cylinders; 3. arrangement of valves; 4. type of cooling; 5. number of cycles (two or four); 6. type of fuel burned; 7. type of ignition.汽车发动机可以按以下几种情况分类： 1按气缸的数量分类；2按气缸排列的力式分类；3按进气方式分类；4按冷却方式分类；5按工作循环的行程数分类（二行程或四行程）6按所用的燃料分类；7按点火方式分类。 The engine is the source of power that makes the wheels go around and the car move. The automobile engine is an internal-combustion engine because the fuel (gasoline) is burned inside it. The burning of gasoline inside the engine produces high pressure in the engine combustion chamber. This high pressure forces piston to move, the movement is carried by connecting rods to the engine crankshaft. The crankshaft is thus made to rotate; the rotary motion is carried through the power train to the car wheels so that they rotate and the moves.发动机是使车轮转动、从而驱动汽车行驶的动力来源。汽车发动机是一种内燃机，因为燃油（汽油）是在发动机内燃烧的。汽油的燃烧在发动机燃烧室中产生的高压力，推动活塞运动，并通过连杆传到发动机曲轴。曲轴转动，动力传动系统将发动机的转动运动传给汽车车轮，从而使车轮及整车转动起来。The engine requires a fuel system to supply it with a mixture of air and fuel. The fuel system does this by pumping liquid gasoline from a tank into the carburetor, a mixing device that mixes the gasoline with air. The mixture is delivered to the engine where it is burned.发动机要求燃料供给系统为之供应汽油混合燃料。燃料系统把汽油从油箱中抽出来，通过化油器-一种把汽油空气进行混合的装置-将可燃混合气输送到发动机，并在那里进行燃烧。The engine also needs a cooling system, the combustion of the air-fuel mixture in the engine creates a very high temperature (as high as 2000 to 2700 ). The cooling system takes heat away from the engine by circulating a liquid coolant (water mixed with antifreeze) between the engine and a radiator. The coolant gets hot as it goes through the engine. It cools off as it goes through the radiator. Thus, the coolant continually takes heat away from the engine, where it could do damage, and delivers it to the radiator. Air passing through the radiator takes heat away from the radiator.发动机还配备有冷却系统，发动机内部的混合气燃烧会产生高温（高达2，000-2，700）。冷却系统通过在发动机和散热器之间流动的液体冷却液（加了防冻液的水）使发动机降温。当冷却液流经发动机时，冷却液就会变热。而流到散热器时又会被冷却，这样使发动机产生的热量不断地被消散掉。经过散热器的空气，将热量从散热器中带走。The engine also includes a lubricating system. The purpose of the lubricating system is to supply all moving parts inside the engine with lubricating oil; the oil keeps moving parts from wearing excessively.发动机还包括润滑系统，润滑系统的作用是向发动机内的各个运动零件提供润滑油。润滑油可是运动零件免于过度磨损。The engine requires a fourth system, the ignition system. The ignition system provides high-voltage electric sparks that ignite, or set fire to, the charges of air-fuel mixture in the engine combustion chambers.发动机的第四个系统是点火系统。点火装置产生高压电火花，从而使发动机燃烧室中的可燃混合气起燃。The fifth is starting system and its purpose is to change the electrical current into the mechanical energy to push the crank-shaft around. By means of this, the engine can be started.发动机的第五个系统是起动系统，起动系统的作用是把电能转变为机械能推动曲轴转动。发动机借助这种办法启动。These five systems are discussed briefly in following sections.这五个系统将在以后的章节中详细讨论。Words and Expressionscombustion chamber 燃烧室；ignition. 点燃；power train 动力传动系统；carburetor 化油器；antifreeze 防冻的；coolant 冷却剂（液态）；crankshaft 曲轴2. Four-stage-engine Operation四行程发动机工作过程The action taking place in the engine cylinder can be divided into four stages, or strokes. “Stroke” refers to piston movement; as stroke occurs when the piston moves from one limiting position to the other. The upper limit of piston movement is called TDC （top dead center）. The lower limit of piston movement is called BDC (bottom dead center). A stroke is piston movement from TDC to BDC or from BDC to TDC. In other words, the piston completes a stroke each time it change its direction of motion.发动机气缸内的工作过程，可以分为四个阶段，或行程。行程涉及活塞的运动；活塞从某一限定位置到另一限定位置的运动称为一行程。活塞运动的上限称为TDC（上止点），下限称为BDC（下止点）。一个行程就是活塞从上止点到下止点，或从下止点到上止点的运动。换句话说，活塞每完成一个行程，就改变一次其运动的方向。Where the entire cycle of events in the cylinder requires four strokes (or two crankshaft revolutions), the engine is called a four-stroke-cycle engine, or a four-cycle engine. The four piston strokes are intake, compression, power, and exhaust.发动机气缸中的全部工作过程分为四个行程的（或者曲轴旋转两周的），叫做四行程循环发动机，或四循环发动机。发动机的四个行程是进气、压缩、做功、排气。Intake stroke. On the intake stroke, the intake valve has opened, the piston is moving downward, and a mixture of air and vaporized gasoline is entering the cylinder through the valve port. The mixture of air and vaporized gasoline is delivered to the cylinder by the fuel system and carburetor.进气行程：在进气行程中，进气门打开，活塞向下移动，可燃混合气通过进气门进入气缸。适当浓度可燃混合气是由燃料系统和化油器提供的。Compression stroke. After the piston reaches BDC, or the lower limit of its travel, it begins to move upward. As this happens, the intake valve closes. The exhaust valve is also closed, so that the cylinder is sealed. As the piston moves upward (pushed now by the revolving crankshaft and connecting rod), the air-fuel mixture is compressed. By the time the piston reaches TDC, the mixture has been compressed to as little as one-tenth of its original volume, or even less. This compression of the air-fuel mixture increases the pressure in the cylinder. When the air-fuel mixture is compressed, not only does the pressure in the cylinder go up, but the temperature of the mixture also increases.压缩行程：在活塞到达下止点时，或者是活塞下限时，活塞开始向上运动。同时，进气门关闭，排气门也关闭，所以这时的气缸是封闭的。当活塞向上运动时（这是由转动的曲轴和连杆推动活塞），可燃混合气被压缩。当活塞到达上止点时，可燃混合气被压缩到只有原体积的在十分之一，甚至更少。当油器混合燃料被压缩时，不仅气缸里的压力上升，可燃混合气的温度也随之增加了。Power stroke. As the piston reaches TDC on the compression stroke, an electric spark is produced at the spark plug. The ignition system delivers a high-voltage surge of electricity to the spark plug to produce the spark. The spark ignites, or sets fire to, the air-fuel mixture. It now begins to burn very rapidly, and the cylinder pressure increases to as much as 3-5 MPa or even more. This terrific push against the piston forces it downward, and a power impulse is transmitted through the connecting rod to the crankpin on the crankshaft. The crankshaft is rotated as the piston is pushed down by the pressure above it.做功行程：当活塞到达压缩行程的上止点时，火花塞产生电火花。电火花是由点火系统向火花塞提供高压电脉冲而产生的。电火花点燃可燃混合气。可燃混合气开始发生剧烈燃烧，气缸内压力达到3-5兆帕，甚至更高。作用于活塞上强大的推动力推动活塞向下运动，并将这一推力通过连杆传到曲轴上的连杆轴颈上。因此，当活塞受压向下运动时，推动曲轴转动。Exhaust stroke. As the piston reaches BDC again, the exhaust valve opens. Now, as the piston moves up on the exhaust stroke, it forces the burned gases out of the cylinder through the exhaust-valve port. Then, when the piston reaches TDC, the exhaust valve closes and the intake valve opens. Now, a fresh charge of air-fuel mixture will be drawn into the cylinder as the piston moves down again toward BDC. The above four strokes are continuously repeated.排气行程：当活塞再一次到达下止点时，排气门打开。同时，活塞向上移动，把废气经排气门排出气缸。随后活塞达到上止点，排气门关闭，进气门打开。当活塞又一次向下移动到达下止点时，新鲜可燃混合气被吸入气缸，上述的四个行程又继续重复。Words and Expressions stroke 行程，冲程；BDC 上止点；TDC 下止点；surge 冲击，脉动；terrific 了不起的，绝妙的；crankpin 曲柄销，连杆轴颈；intake stroke 吸气冲程；compression stroke 压缩冲程；power stroke 做功冲程；exhaust stroke 排气冲程；fresh charge （发动机）吸入的新鲜混合油气 3. Two-stage-engine Operation二行程发动机工作过程In the four-stroke-cycle engine, already discussed in lesson 1、2, the complete cycle of events requires four piston strokes (intake, compression, power, and exhaust). In the two-stroke-cycle, or two-cycle, engine, the intake and compression strokes and power and exhaust strokes are in a sense combined. This permits the engine to produce a power stroke every two piston strokes, or every crankshaft rotation.我们在第二课中讲到，四行程发动机整个工作循环需要活塞完成进气、压缩、做功、排气四个行程。在二行程发动机中，进气和压缩行程以及做功和排气行程是分别合并在一起的，这使得二行程发动机每两个行程，即曲轴旋转一周，就完成一次工作循环。In the two-cycle engine, the piston acts as a valve, clearing valve ports in the cylinder wall as it nears BDC.A fresh air-fuel charge enters through the intake port, and the burned gases exit through the exhaust port. The complete cycle of operation is as follows: As the piston nears TDC, ignition takes place. The high combustion pressures drive the piston down, and the thrust through the connecting rod turns the crankshaft. As the piston nears BDC，it passes the intake and exhaust ports in the cylinder wall. Burned gases, still under some pressure, begin to stream out through the exhaust port. At the same time, the intake port, now cleared by the piston, begins to deliver air-fuel mixture, under pressure, to the cylinder. The top of the piston is shaped to give the incoming mixture an upward movement. This helps to sweep the burned gases ahead and out through the exhaust port.在二行程发动机中，活塞起到阀门的作用，当活塞接近下止点时，使气缸壁上的进排气口打开。新的可燃混合气通过进气口进入，燃烧过的废气从排气口排出。整个工作过程如下：当活塞接近上止点时，发动机点火，燃烧产生的高压驱动活塞向下运动，通过连杆，推动曲轴转动。当活塞接近下止点时，经过气缸壁上的进排气口，燃烧过的气体，仍有剩余压力，开始从排气口喷出。同时，活塞使进气口露出，受压缩的可燃混合气开始进入气缸。活塞顶部的形状使进入气缸的可燃混合气向上运动，这样有助于扫气，引导燃烧过的废气向上运动并从排气口排出。After the piston has passed through BDC and stars up again, it passes both ports, thus sealing them off. Now the fresh air-fuel charge above the piston is compressed and ignited. The same series of events takes place again and continue as long as the engine runs.在活塞通过下止点，并开始上升时，活塞经过进气口和排气口，将其堵住。这时候活塞上方新的可燃混合气受压缩后点火。只要发动机运转，同样的动作就会反复不断地发生。We mentioned that the air-fuel mixture is delivered to the cylinder under pressure. In most engines, this pressure is put on the mixture in the crankcase. The crankcase is sealed except for a leaf, or reed, valve at the bottom. The reed valve is a flexible, flat metal plate that rests snugly against the floor of the crankcase. There are holes under the reed valve that connect to the engine carburetor. When the piston is moving up, a partial vacuum is produced in the sealed crankcase. Atmospheric pressure lifts the reed valve off the holes, and air-fuel mixture enters the crankcase. After the piston passes TDC and starts down again, pressure begins to build up in the crankcase. This pressure closes the reed valve so that further downward movement of the piston compresses the tapped air-fuel mixture in the crankcase. The pressure which is built up on the air-fuel mixture then causes it to flow up through the intake port into the engine cylinder when the piston moves down far enough to clear the intake port.我们曾提到可燃混合气是被压进气缸的。在大多数发动机中，可燃混合气是在曲轴箱中受压的。除了底部有一叶片阀（片簧阀）之外，曲轴箱是密封的。片簧阀是一片柔韧、平整的金属片。金属片紧贴在曲轴箱的底部。在片簧阀的下面有孔道与化油器相连。当活塞向上运行时，就会在密封的曲轴箱里产生部分真空。大气的压力将片簧阀提起。打开通道，可燃混合气进入曲轴箱。当活塞经过上止点，又开始向下运动时，压力就开始在曲轴箱中产生。压力使片簧阀关闭，这样，活塞进一步的向下运动压缩留在曲轴箱中的可燃混合气。当活塞向下运动直到露出进气口，可燃混合气所具有的压力使其上升，通过进气口进入气缸。The two-stroke engine is not only very simple but gives nearly twice the power of a four stroke engine from a cylinder of given size, but it is wasteful of gasoline, as some mixture inevitably finds its way into the exhaust system on the combines intake/exhaust stroke, and there are always some combustion products left in the cylinder which reduce the rapid burning of the fuel. This kind of engine is always used in motorcycles.二行程发动机不仅结构简单，而且其功率相当于具有相同气缸容积的四行程发动机的二倍。但是，在进气和排气行程中，一些可燃混合气不可避免地进入排气系统，并且总会有一些燃烧物滞留在气缸中，致使燃料不能充分燃烧。所以二行程发动机耗油较大。通常使用在摩托车上。Words and Expressionssweep 扫气；connecting rod 连杆；crankcase 曲轴箱；seal off 密封；leaf （reed） valve 片簧阀；air-fuel charge 可燃混合油气4. Diesel Engine Operating Features柴油发动机工作特点We all know that diesel engines, in principle, work in the same way as gasoline engines do. Both kinds of engines are internal-combustion engines, but each of them has its characteristic features. As their names suggest this type of engines burn their fuel inside the working parts of the engines. “Internal” means “inside”, “combustion” means “catching fire or burning”. In any internal combustion engine, burning fuel heats air which consequently expands, and in expanding exists a push to a piston which, in turn, rotates the engine crankshaft through a connecting rod.我们都知道柴油机和汽油机的工作原理是相同的。这两种发动机都是内燃机，但各自却具有自身的特点。正如这一类型发动机的名称所提示的，发动机的燃料是在发动机工作部件的内部燃烧的。“internal”意思是“内部”，“combustion”意思是“着火或燃烧”。在任何内燃机中，燃烧的燃料使空气受热并迅速膨胀，产生推力推动活塞，通过连杆推动发动机的曲轴。Now let us compare the diesel engine with the gasoline engine. Firstly, the explosive mixture of the gasoline engine is provided by a carburetor, but in the case of the diesel engine the supply is affected by an injection or “jerk” pump which forces a “short” of fuel into each cylinder in turn according to the correct firing sequence. Secondly, the fundamental difference between gasoline and diesel engines is that in the gasoline engine the source of the heat for igniting the charge, namely, an electric spark, is generated outside the engine, and is taken, as it were, into the waiting charge at the required instant. In the diesel engine the source of heat for igniting the charge is created within the engine by compressing pure air to a degree that will initiate combustion and then injecting the fuel at the right time in relation to the movement of the crankshaft. Both classes of engines are of very similar construction. But as the diesel engine is called upon to withstand very much greater stresses due to higher pressures in cylinders, it has to be of more substantial construction, and is thus heavier. In general, the diesel engine may weigh about 9.25 kilograms per kilowatt. The most important advantage of the gasoline engine is its lower weight per kilowatt. The gasoline engine for automobiles weighs about 6.17 kilograms per kilowatt, and gasoline engines for airplanes may weigh as little as 0.77 kilograms per kilowatt. This advantage prevents the diesel engine from replacing the gasoline engine in some automobiles and airplanes.现在，让我们比较一下柴油机和汽油机。首先，汽油机的可燃混合气是由化油器提供的，而柴油机由喷油泵或脉动泵按照正确的点火顺序将燃油轮流的喷入各气缸的。第二，汽油发动机与柴油发动机的基本区别在于汽油机中点燃混合气的热源是电火花。电火花是在发动机外面产生的。按照实际情况来说，电火花总是在需要的时刻进入待燃的混合气中。在柴油发动机中，使燃油点火的热源是靠将空气压缩到可以引燃的程度来产生的，并在对应于曲轴转动的恰当时刻喷入燃料。这两类机型结构是很相似的，但是由于气缸要产生较大的压力，而要求柴油发动机能够经受非常大的应力，它的结构就需要更加坚固，其质量也因此就得更大。一般来说，柴油机比质量约为9.25公斤每千瓦。汽油机最重要的优点是每千瓦的质量较轻。汽车用汽油发动机比质量为6.17公斤每千瓦，而飞机用汽油发动机的比质量小到0.77公斤每千瓦。汽油机的这一优点使柴油机无法代替某些汽车以及飞机上使用的汽油发动机。However, the diesel engine is more efficient, because it has higher compression ration. Its ratio may be as high as 16 to 1. Up to 40 percent of the chemical energy of the burning fuel may be changed into mechanical energy. In addition, the diesel engine runs cooler than the gasoline engine. This advantage is especially obvious at lower speeds. Diesel oil is not only cheaper than gasoline, but also safer to store.但是，柴油发动机的效率更高些，因为柴油机具有较高的压缩比16比1。高达百分之四十的燃料燃烧产生的化学能转化为机械能。此外，柴油发动机比汽油发动机的运转温度低。这一优点在运转速度低时尤为明显，柴油不仅比汽油便宜，而且贮存更为安全。Words and Expressionsdiesel：柴油机； internal-combustion engines：内燃机； jerk pump：脉动史喷油泵；compression ration：压缩比5. Engine Cylinder Block Crankcase发动机气缸体 曲轴箱We have seen how the mixture of air and fuel is delivered by the fuel system to the engine cylinder, where it is compressed, ignited, and burned. We have noted that this combustion produces a high pressure that pushes the piston down so that the crankshaft is rotated. Now let us examine the various parts of the engine in detail.我们已经了解油气混合燃料是如何通过燃料供给系统输送到发动机气缸的，并在气缸中压缩、点火、燃烧。我们已知道燃烧产生高压，并推动活塞下行，带动曲轴转动。现在让我们详细研究一下发动机的各部分结构。Engine cylinder blockThe cylinder block of liquid-cooled engines forms the basic framework of the engine. Other parts are attached to the cylinder block or are assembled in it. The block is cast in one piece from gray iron or iron alloyed with other metals, such as nickel or chromium. Some blocks are cast from aluminum. The block contains not only the cylinders but also the water jackets that surround them. In aluminum blocks, cast-iron or steel cylinder sleeves (also called bore lines) are used. These metals have better wearing qualities than aluminum and can better withstand the wearing effect of the pistons and ring moving up and down in the cylinders. For most engines, cast iron has been found to be a satisfactory cylinder-wall material. However, in some small engines, the cylinder walls are plated with chromium, a very hard metal, to reduce wall wear and lengthen their life.发动机气缸体水冷发动机的气缸体是发动机的基本构件，其它部件都支承或安装在它上面。缸体是由灰铸铁或含有镍或铬的合金铸铁整体铸造而成的。有的缸体由铝浇铸而成。缸体不仅包括气缸，而且包括环绕的水套。由铝铸造的气缸中，装有铸铁或钢制的气缸套（或称之为气缸衬套）。这类金属的耐磨性比铝更好，能更好地经受住活塞和活塞环在气缸中上下运动产生的磨损。在大部分发动机中，采用铸铁作为气缸壁面的良好材料。而在一些小型发动机中，气缸壁面镀铬，铬是一种非常耐磨的金属，可减少气缸壁的磨损并延长使用寿命。Cylinder HeadThe cylinder head is usually cast in one piece from iron, from iron alloyed with other metals, or from aluminum alloy. Aluminum has the a