内燃机专业英语教案
2020-03-02 06:54:17 来源：范文大全收藏下载本文
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 Claification 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 Claification 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）
1 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 Claification 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
3 1.Engine Claification and Overall Mechanics
发动机的分类和总体结构
The automobile engines can be claified 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 preure in the engine combustion chamber.This high preure 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臵--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
4 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 paing 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 exceively.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。点火装臵产生高压电火花，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 discued briefly in following sections.这五个系统将在以后的章节中详细讨论。
5 Words and Expreions combustion 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 6
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；活塞从某一限定位臵到另一限定位臵的运动称为一行程。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, compreion, 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。
Compreion 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 7 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 compreed.By the time the piston reaches TDC, the mixture has been compreed to as little as one-tenth of its original volume, or even le.This compreion of the air-fuel mixture increases the preure in the cylinder.When the air-fuel mixture is compreed, not only does the preure 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 compreion 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 preure 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 preure 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.
8 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 Expreions
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；compreion 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 discued in leon
1、2, the complete cycle of events requires four piston strokes (intake, compreion, power, and exhaust).In the two-stroke-cycle, or two-cycle, engine, the intake and compreion 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 preures drive the piston down, and the thrust through the connecting rod turns the crankshaft.As the piston nears BDC，it paes the intake and exhaust ports in the cylinder wall.Burned gases, still under some preure, 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 preure, 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 10 口排出。
After the piston has paed through BDC and stars up again, it paes both ports, thus sealing them off.Now the fresh air-fuel charge above the piston is compreed 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 preure.In most engines, this preure 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 preure lifts the reed valve off the holes, and air-fuel mixture enters the crankcase.After the piston paes TDC and starts down again, preure begins to build up in the crankcase.This preure closes the reed valve so that further downward movement of the piston comprees the tapped air-fuel mixture in the crankcase.The preure 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 11 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 Expreions sweep 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 compreing 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 claes of engines are of very similar construction.But as the diesel engine is called upon to withstand very much greater strees due to higher preures 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
13 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 compreion 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 Expreions diesel：柴油机； internal-combustion engines：内燃机； jerk pump：脉动史喷油泵；compreion 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 compreed, ignited, and burned.We have noted that this combustion produces a high preure 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 block The cylinder block of liquid-cooled engines forms the basic framework of the engine.Other parts are attached to the cylinder block or are aembled 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。
15 Cylinder Head The cylinder head is usually cast in one piece from iron, from iron alloyed with other metals, or from aluminum alloy.Aluminum has the advantage of combining lightne with high heat conductivity.That is, an aluminum head tends to turn cooler, other factors being equal.There are two types of head, L head and I head.Cylinder head contains water jackets for cooling; in the aembled engine, these water jackets are connected through openings to the cylinder-block water jackets.Spark-plug holes are provided, along with pockets into which the valves can move as they open.气缸盖
气缸盖通常由铁、铁合金或铝合金铸成。铝兼有重量轻、导热好的优点。也就是说，其它因素一样时，铝盖更容易冷却。有两种气缸，L型气缸盖和I型气缸盖。气缸盖带有用于冷却的水套。在装配发动机时，这些水套通过出水口与气缸气缸盖上留有火花塞口和凹槽，凹槽使气门打开时可以移动。
Gaskets The joint between the cylinder block and the head must be tight and able to withstand the preure and heat developed in the combustion chambers.The block and head cannot be machined flat and smooth enough to provide an adequate seal.Thus, gaskets are used.Head gaskets are made of thin sheets of soft metal or asbestos and metal.All cylinder, water, valve, and head-bolt openings are cut out.When the gasket is placed on the block and the head installed, tightening of the head bolts (or nuts) squeezes the soft metal so that the joint is effectively sealed.Gaskets are also used to seal joints between other parts, such as between the oil pan, manifolds, or water pump and the block.气缸垫
气缸体与气缸盖之间的结合处必须保持密封，并且能够承受燃烧室产生的高压和高温。机器加工并不能使气缸体和气缸盖平整光滑到严丝密缝，这样就要使用气缸垫。气缸盖用的密封垫是用软金属薄片或金属和石棉组成的薄片制成，留出所有的气缸孔、水道孔、气门孔和气缸盖螺栓孔。当气缸垫装在气缸体上，然后装上气缸盖以后，气缸盖螺栓就压紧软金属垫，这样结合处就完全密封了。密
16 封垫也同样用于密封其它部件之间的结合处，例如，油底壳、歧管、水泵与气缸体之间的密封。
Oil Pan The oil pan is usually formed of preed steel.It usually holds 5 to 10 litres of oil, depending on the engine design.The oil pan and the lower part of the cylinder block together are called the crankcase; they enclose, or encase, the crankshaft.The oil pump in the lubricating system draws oil from the oil pan and sends it to all working parts in the engine.The oil drains off and runs down into the pan.Thus, there is constant circulation of oil between the pan and the working parts of the engine.油盘
油盘通常用薄钢板冲压制成。依其设计不同，油盘的容量通常由5到10升不等。油盘和气缸体的下部共同称为曲轴箱，用来密封或罩住曲轴。润滑系统中的油泵把机油从油中抽上来，送到发动机的各个活动部件。机油再流下来回到油盘。这样，机油就在和发动机的各个部件之间不断循环流动。
Words and Expreions cylinder block 气缸体；block crankcase 曲轴箱；framework 结构，车架；
gray iron 灰铸铁；water jacket 水套； plate……with 镀金属；cylinder head
气缸盖；gaskets 密封垫；asbestos 石棉；manifold 岐管；oil pan 油盘；
pocket 凹槽；bore liner 气缸衬套
6. Piston Connecting Rod
活塞
连杆
Piston The piston is eentially a cylindrical plug that moves up and down in the engine cylinder.It is equipped with piston rings to provide a good seal between the cylinder wall and piston.The piston absorbs heat from the gas, and this heat must be carried away if the metal temperature is to be carried away if the metal temperature is to be held within safe limits.The constant reversal of the piston travel sets up inertial forces, which increase both with the weight of the piston and with its speed.For this reason, designers try to keep piston weight low, particularly in high-speed engines.As lower hood lines and over-square engines became popular, the semi-slipper and full-slipper pistons came into use.On these pistons the number piston rings was reduced to three, two compreion and one oil-control.One reason for the slipper piston is that, on the short stroke, over-square engine, the piston skirt had to be cut away to make room for the counterweights on the crankshaft.Also, the slipper piston, being shorter and having part of its skirt cut away, is lighter.This reduces the inertial load on the engine bearings and, in addition, makes for a more responsive engine.The lighter the piston, the le the bearing load and the longer the bearings will last.Another way to lighten the piston is to make it of light metal.The idea piston material would be light and strong, conduct heat will, expand only slight when heated, resist wear, and be low in cost.Thus, most automotive-engine pistons today are made of aluminum, which is le than half as heavy as iron.Iron pistons were common in the earlier engines.Aluminum expands more rapidly than iron with increasing temperature, however, and since the cylinder block is of iron, special provisions must be made to maintain proper piston clearance at operating temperatures.To take care of it, the crown is machined on slight taper, the diameter being greatest where the crown meets the skirt and becoming le toward the top.活塞
实质上活塞是一个在气缸中上下移动的圆筒状的塞子。上面装有活塞环，从 18 而使活塞和气缸壁之间具有良好的密封性。活塞从气体中吸热，假如要使金属的温度保持在安全限度以内，就必须散热。活塞的不断往复运动产生了惯性力，惯性力随活塞的重量及其速度的增加而增大。为此，设计者设法使活塞造的轻些，特别是高速发动机。由于低发动机罩和短行程发动机的进一步普及，半围延裙活塞和滑裙式活塞开始使用。在这些活塞中，活塞环的数量减少到三个，即两个气环，一个油环。使用滑裙活塞的原因是：短行程发动机需除去部分活塞裙部，从而为曲轴的平衡重让出空间。滑动活塞长度较短，由于裙部被部分切除后重量较轻。这就减少了发动机轴承上的惯性负荷，使发动机反应更加灵敏。活塞越轻，轴承的负荷越小，轴承的工作寿命就越长。还有一种可使活塞质量减小的办法，就是用轻金属制造活塞。理想的活塞材料应该重量轻、强度高、导热好、热膨胀小、耐磨、价格低廉。因此今天大多数的汽车发动机活塞都是铝制成的，铝的重量还不到铸铁的一半。铸铁活塞在早期的发动机中广泛使用。随着温度的增加，铝比铸铁膨胀量更大。然而，由于气缸体是铸铁制成的，必须采取特殊的措施，以维持工作温度下正常的活塞间隙。考虑到这一点，活塞顶部要加工成略呈锥状体，即活塞顶部与活塞裙部交接处直径最大，愈向顶部，直径愈小。
Piston Rings A good seal must be maintained between the piston and cylinder wall to prevent blow-by.―Blow-by‖ is the name that describes the escape of burned gases from the combustion chamber, past the piston, and into the crankcase.In other words, these gases ―blow by‖ the piston.It is not practical to fit the piston to the cylinder closely enough to prevent blow-by.Thus, piston rings must be used to provide the neceary seal.The rings are installed in grooves in the piston.Actually, there are two types of rings, compreion rings and oil-control rings.The compreion rings seal in the air-fuel mixture as it is compreed and also the combustion preures as the mixture burns.The oil-control rings scrape off exceive oil from the cylinder wall and return it to the oil pan.活塞环
在活塞与气缸壁之间必须保持良好的密封以防止漏气。―漏气‖这一名称是指燃烧气体从燃烧室溢出，经过活塞进入曲轴箱。换句话说，这些气体是通过活塞溢出的。实际上，活塞与气缸间再严密也免不了会漏气。所以活塞环就用来提供
19 必要的密封。活塞环装在活塞的凹槽中。事实上有两种活塞环，气环和油环。当可燃混合气压缩时，气环密封可燃混合气；当可燃混合气燃烧时气环可阻止所产生的压力不外溢。油环的作用是刮去气缸壁上多余的机油，使之流回油底壳。
The rings have joints (they are split) so that they can be expanded and slipped over the piston head and into the receed grooves cut in the piston.Rings for automotive engines usually have butt joints, but in some heavy-duty engines, the joints may be angles, lapped, or of the sealed type.活塞环有接口（也就是有一缝隙）。这样可以使端部扩张并滑入活塞上的凹槽中。汽车发动机上的活塞环通常有接口。但在一些重型发动机上，活塞环的接口可以是斜角接口、搭接式或是密封式的。
The rings are somewhat larger in diameter than they will be when in the cylinder.Then, when they are installed, they are comprees so that the joints are nearly closed.Compreing the rings gives them an initial tension; they pre tightly against the cylinder wall.活塞环的直径要略大于装入气缸时的直径。这样，在活塞环装入气缸中时，活塞环就会被压缩，接头几乎闭合了。受压使之具有预张力，活塞环就紧紧地压在气缸壁上。
Connecting Rod The connecting rod is attached at one end to a crankpin on the crankshaft and at the other to a piston, through a piston pin or wrist pin.The connecting rod must be very strong and rigid and also as light as poible.The connecting rod carries the power thrusts from the piston to the crankpin.At the same time, the rod is in eccentric motion.To minimize vibration and bearing loads, the rod must be light in weight.To maintain good engine balance, connecting rods and caps are carefully matched in sets for engines.All rods in an engine must be of equal weight; if they are not, noticeable vibration may result.In original aembly, rods and caps are individually matched to each other and usually carry identifying numbers so they will not be mixed if the engine is disaembled for service.They must not be mixed during any service job, since this could result in poor bearing fit and bearing failure.
20 连杆
连杆的一端与曲轴的连杆轴颈相连，另一端通过活塞销与活塞相连。连杆必须具有足够的强度和刚度，并且要尽可能轻。连杆的作用是将活塞承受的压力传给连杆轴颈。同时，连杆做偏心运动。为了把振动和轴承负荷减小到最低限度，连杆的重量必须尽可能的轻。为了保持发动机的良好平衡，连杆和连杆盖都要精心配套。发动机连杆的质量都必须相等，否则，就会产生明显的振动。在进行装配时，连杆和连杆盖都必须一一相互匹配。为了防止拆装发动机时发生匹配错误，通常在部件上刻上标号。在维修过程中，千万不能弄混，因为这会造成轴承不配套及轴承的损坏。
Words and Expreions counterweight
平衡重；groove 凹槽；rece 凹口；lap 搭接；eccentric 偏心的；lower hood lines 低发动机罩；over-square engine 短行程发动机；semi-slipper piston 半裙式活塞；full-slipper piston
全裙式活塞；match in set 配套；blow-by 漏气；initial tension 初张力；poor bearing fit 轴承不配套； bearing failing 轴承故障。 21
7.Crankshaft Flywheel
曲轴 飞轮
Crankshaft The crankshaft is a one-piece casting or forging of heat-treated alloy steel of considerable mechanical strength.The crankshaft must be strong enough to take the downward thrusts of the pistons during the power strokes without exceive distortion.In addition, the crankshaft must be carefully balanced to eliminate undue vibration resulting from the weight of the offset cranks.To provide balance, crankshafts have counterweights opposite the cranks.Crankshafts have drilled oil paages through which oil can flow from the main to the connecting-rod bearings.The front end of the crankshaft carries three devices, the gear or sprocket that drives the camshaft, the vibration damper, and the fan belt pulley.The pulley drives the engine fan, water pump, and generator with a V belt.曲轴
曲轴是由合金铸造或锻造，经过热处理，具有一定的机械强度的整体结构。曲轴必须具有足够的强度，以承受活塞在做功行程期间向下运动产生的冲力，而不会产生过度的扭曲。另外，曲轴必须仔细地给予平衡，以避免曲柄重力偏移而引起过度振动。为了保持平衡，曲轴必须具有与曲柄相对应的平衡重。曲轴上钻有油道，润滑油可以从主轴承流到连杆轴承上。在曲轴的前端有三个装臵：驱动凸轮轴的齿轮或链轮、减震器和风扇皮带轮。皮带轮通过V形皮带驱动发动机风扇，水泵和发电机。
Flywheel The flow of power from the engine cylinders is not smooth.Although the power impulses overlap (on six-and eight-cylinder engines), there are times when more power is being delivered than at other times.This tends to make the crankshaft speed up and then slow down.However, the flywheel combats the tendency.The flywheel is a comparatively heavy wheel bolted to the rear end of the crankshaft.The inertia of the flywheel tends to keep it turning at constant speed.Thus, the flywheel absorbs energy as the crankshaft tries to speed up and gives back energy as the crankshaft tries
22 to slow down.In effect, the flywheel absorbs power from the engine during the power stroke (or speedup time) and then gives it back to the engine during the other three strokes (or slowdown time) of the cycle.飞轮
发动机气缸所产生的动力是不均匀的。尽管在六缸或八缸发动机中，动力冲击重叠发生，但是有时产生的动力会大些。这会使曲轴的运转速度忽快忽慢，然而飞轮可以克服这种倾向。飞轮是一个很重的轮子，用螺栓固定在曲轴的后端。飞轮的惯性使飞轮保持恒速运动。这样，飞轮在曲轴加速时把能量贮存起来，当曲轴速度减慢时再释放出来。事实上，飞轮在做功行程（或加速过程）中贮存动能，而在其它三个行程（或减慢过程）中，把动能释放出来。
Words and Expreions forging 锻件；sprocket 扣链齿（链轮上与链条结合的齿）；damper 减震器；flywheel 飞轮；bolt 螺栓；one-piece 整体 23
8.Valves and Vales Train 气门与气门传动组
Valves and Valve Train There are two openings, or ports, in the enclosed end of the cylinder.One of the ports permits the mixture of air and gasoline vapor to enter the cylinder.The other port permits the burned gases, after combustion, to exhaust, or escape, from the cylinder.The two ports have valves aembled into them.These valves close off one or the other port, or both ports, during the various stages of engine operation.That is to say, each cylinder has two valves, an intake valve and exhaust valve.The cam lobes on the camshaft are so related to the crankshaft crankpins through the gear or sprockets and chain as to cause the valves to open and close with the correct relationship to the piston strokes.气门和气门机构
在气缸封闭的一端，有两个开口，或称为孔。一个开口使可燃混合气可以及时进入气缸。另一个开口是让燃烧后的气体从气缸内排出。这两个开口都装有气门。这些气门在发动机工作顺序的不同阶段，关闭一个开口，（或另一个开口），或者同时关闭两个开口。也就是说，每个气缸有两个气门，即进气门和排气门。凸轮轴上的凸轮和凸角通过齿轮或链轮和链条与曲轴轴颈相连，这样，可以使气门按照活塞行程的正确顺序开启和关闭。
The valves are nothing more than accurately machined metal plugs (on long stems) that close the openings when they are seated (have moved up into the openings).When the valve closes, it moves up so that the outer edge rests on the seat.In this position, the valve port is closed so that air or gas cannot escape from the cylinder.气门不过是装在阀杆上加工精细的金属塞而已。当气门就位时（向上移动阀口），即可将气门关闭。气门关闭时，气门向上移动，这样气门的边缘就正好落在气门座上。在这一位臵上，气门口关闭，混合气就不会从气缸中逸出。
A spring on the valve stem tends to hold the valve on its seat (closed).The lower 24 end of the spring rests against the cylinder head.The upper end rests against a flat washer, or spring retainer, which is attached to the valve stem by a retainer lock (also called a keeper).The spring is under compreion, which means that it tries to expand and therefore spring-loads the valve in the closed position.气门杆上的弹簧使气门保持在气门座上（关闭状态）。弹簧的下端抵在气缸盖上。上端抵在弹簧座上，在弹簧座的下面用拴销（或叫做定位销）加以定位。弹簧处于―压缩‖状态时，意味着弹簧试图伸展，气门受弹簧作用而处于关闭状态。
A valve-opening mechanism opens the valve, or lifts it off its seat, at certain times.On most engines, this mechanism, called the valve train, includes a cam on the camshaft, a valve lifter, a push rod, and a rocker arm.As the camshaft turns, the cam lobe comes around under the valve lifter.This raises the lifter, which in turn pushes upward on the push rod.The push rod, as it is lifted, causes the end of the rocker arm to move up.The rocker arm pivots around its supporting shaft so that the valve en of the rocker arm is forced downward.This downward movement forced the valve to move downward off its seat so that it opens.After the cam lobe moves out from under the valve lifter, the valve spring forces the valve up onto its seat again.使气门开启的机械装臵在适当的时刻开启气门或者将气门从气门座上提起。在大多数发动机中，这套装臵叫做气门机构。这套装臵中包括凸轮轴上的一个凸轮、一个气门挺杆、一个气门推杆和一个摇臂。当凸轮轴转动时，凸轮凸角转到气门挺杆下面，是挺杆上举，挺杆推动推杆。当推杆升起时，摇臂的端部向上移动。摇臂围绕支承轴旋转，气门与摇臂相对应的一端压下。向下的运动使气门向下移动离开气门座，气门被打开。当凸轮凸角离开气门挺杆，气门弹簧使气门重新回到气门座上。
In the other kind of valve mechanism for an engine, the valves are located in the cylinder block instead of the head.With this arrangement, the camshaft is directly below the valve lifter, and no push rods or rocker arms are neceary.Although the valve-in-block arrangement is a simple design, most automotive engines are valve-in-head type.The valve-in-head engine has certain advantages.另一种气门机构的气门是装在气缸体上，而不是装在气缸盖上。在这种装臵 25 中，凸轮轴直接装在气门挺杆下，并且不必有推杆或摇臂。虽然侧臵气门发动机结构设计简单，大多数汽车发动机却都是顶臵式气门，因为顶臵式气门发动机确有优点。
Cam and Camshaft A cam is a device that can change rotary motion into linear, or straight-line, motion.The cam has high spot, or lobe; a follower riding on the cam will move away from or toward the camshaft as the cam rotates.In the engine, cams on the camshaft cause the intake and exhaust valves to open.There is a cam on the camshaft for each valve, or two cams per cylinder.The camshaft is driven by gears, or by a chain, from the crankshaft.It turns at one-half crankshaft speed.In the four-cycle engine, every two revolutions of the crankshaft produce one revolution of the camshaft and one opening and closing.The cam lobes are so positioned on the camshaft as to cause the valves to open and close in the cylinders at the proper time with respect to the actions taking place in the cylinders.凸轮和凸轮轴
凸轮是能够使旋转运动转变为线性或直线运动的装臵。凸轮有一个顶点，或叫做凸轮凸角。当凸轮转动时，凸轮上的从动件也随着凸轮轴来回移动。在发动机中，凸轮轴上的凸轮控制进气门和排气门的开启和关闭。每个气门有一凸轮，每一个气缸就有两个凸轮。凸轮轴由曲轴通过正时齿轮或链条来驱动。凸轮轴的转速为曲轴转速的一半。在四行程发动机中，曲轴每转动两圈，凸轮轴转动一圈，使气门开启和关闭一次。曲轴上凸轮凸角的位臵使气门在恰当的时候开关，以便与气缸的工作顺序相一致。
In addition, the camshaft has an eccentric to operate the fuel pump and a gear to drive the ignition distributor and oil pump.此外，凸轮轴还带动一个驱动燃料泵的偏心轮和一个带动分电器和油泵的齿轮。
stem：柄，堵住；seat：气门座；rest：安放；spring：弹簧；washer：垫圈；lifter：气门挺杆；push：推杆；valve train：气门组；cam rod：凸轮凸角；rocker arm：气门摇杆臂；valve-in-head：顶臵式气门；valve-in-block：到臵式气门
26
9.Engine Fuel System 发动机燃油系统
The fuel system has the job of supplying a combustible mixture of air and fuel to the engine.The fuel system must vary the proportions of air and fuel to suit different operating conditions.When the engine is cold, for example, then the mixture must be rich (have a high proportion of fuel).The reason for this is that the fuel does not vaporize rapidly at low temperatures.Therefore, extra fuel must be added to the mixture so that there will be enough vaporized fuel to form a combustible mixture.燃料供给系统的作用是向发动机提供由空气和燃料所组成的可燃混合气。燃料系统必须改变空气和燃料的比例以适应不同的运行状态。例如，当发动机冷车时，就必须提供较浓的混合气（具有较高的燃油比例）。这是因为在低温下燃油不能迅速气化，因此，要在混合气中额外增加燃油，这样才有足够气化燃料形成可燃混合气。
The fuel system consists of the fuel tank, fuel pump, fuel filter, carburetor, intake manifold, and fuel lines, or tubes, connecting the tank, pump, and carburetor.Some gasoline engines use a fuel-injection system; in this system, a fuel-injection pump replaces the carburetor.燃料系统包括汽油箱、汽油泵、汽油滤清器、化油器、进气歧管以及连接油箱、油泵和化油器的油管。有的汽油发动机使用的是一套燃油喷射系统，在这一系统中，然油喷射泵取代了化油器。
The fuel tank, in which gasoline is stored, is normally located at the rear of the vehicle.It is made of sheet metal and is attached to the frame.汽油箱用来贮存汽油，通常安装在汽车的后部。油箱由金属板制成，固定在车架上。
A fuel pump delivers fuel from the tank to the carburetor.There are two general types of fuel pump, mechanical and electric.油泵把油箱中的燃油抽出送到化油器中。通用的油泵有两种：机械泵和电子泵。
27 The fuel system has filters and screens to prevent dire in the fuel from entering the fuel pump or carburetor.Dirt could, of course, prevent normal operation of these units and cause poor engine performance.燃料系统装有滤清器和过滤网，防止燃油中的杂物进入燃油泵或化油器。否则，污物会影响这些部件的正常运转，并引起发动机运转不良
The carburetor is eentially a mixing device which mixes liquid gasoline with air.In this proce, it throws a fine spray of gasoline into air paing through the carburetor on its way to the engine.The gasoline vaporizes and mixes with the air to form a highly combustible mixture.This mixture then enters the engine combustion chambers, where it is ignited.It burns, causing the engine to produce power.The mixture must be of varying degrees of richne to suit engine operating conditions.It must be rich (have a higher percentage of fuel) for starting, acceleration, and high-speed operation.And it should lean out (become le rich) for operation at intermediate speed with a warm engine.The carburetor has several different circuits, or paages, through which fuel and air-fuel mixture flow under different operating conditions to produce the varying richne of the air-fuel mixture.化油器实质上是一个把液体燃油与空气相混合的混合气形成装臵。在这一过程中，化油器把燃油以雾状喷入流经化油器的空气中，然后进入发动机。雾化燃油和空气形成高度易燃的混合气。可燃混合气进入发动机的燃烧室，并在那里被点燃。可燃混合气燃烧，使发动机产生动力。混合气的浓度比例可以改变，以适应发动机的运行状况。汽车在启动、加速和高速行驶时，需要含燃油浓度较高的混合气；热状态下的发动机中速行驶时，混合气含燃油浓度则可低一些。化油器有几个不同的供油系统或通道，通过这些供油系统，在不同的行驶状态下，可提供浓度不同的可燃混合气。 Words and Expreions combustible：易燃的；filter：过滤器；manifold：多种的；sheet：薄片；dirt：污垢；fine：细小的；spray：雾状；richne：可燃成分高的混合燃料；throw into：喷入；lean out：（内燃机的混合燃料等）可燃成分降低 28
10.Engine Lubricating System
发动机润滑系统
There are a great many moving metal parts in the engine.These parts must be protected by lubricating oil so that there will be no actual metal- to-metal contact.The moving parts, in effect, float on films of oil.发动机中有大量的运动的金属零件。要保护这些零件就必须进行润滑，这样可以避免金属零件之间的直接接触。实际上，在运动零件的表面总是覆盖着一层油膜。
Two types of lubricating systems have been used on four-cycle automotive engines, splash and combination splash and preure feed.四行程发动机使用两种润滑系统：飞溅式润滑和飞溅压力结合送油式润滑。 In the splash lubricating system, oil is splashed up from the oil pan or oil trays in the lower part of the crankcase.The oil is thrown upward as droplets or fine mist and provides adequate lubrication to valve mechanisms, piston pins, cylinder walls, and piston rings.在飞溅润滑系统中，油从机体下部的油盘活油底壳中飞溅上来。飞溅上来的油形成油滴或油雾，使气门机构、活塞销、气缸壁和活塞环得到充分的润滑。
In the combination splash and preure feed lubricating system, an oil pump takes oil from the oil pan and forces it through holes drilled in the engine block and crankshaft.This oil thereby reaches the various bearings that support rotating shafts and the different moving parts in the engine.It covers the surfaces of the moving parts in the engine.It covers the surfaces of the moving parts to prevent metal- to- metal contact and undue water of the parts.在飞溅压力结合送油润滑系统中，油泵从油盘中把油抽上来并压入发动机机体上和曲轴上的油道，被输送到发动机的曲轴和各种运动零件的每个轴承上。润滑油在运动零件表面形成油膜，以防止金属零件表面直接接触以及零件的过度磨损。
In this system, cylinder walls are lubricated by splashing oil thrown off from the
29 connecting-rod bearing.The lubricating oil circulating through the engine to all moving parts requiring lubrication performs other jobs.在这一系统中，气缸壁是由连杆轴承运动飞溅起来的油进行润滑的。润滑油在发动机的所有活动部件之间循环流动，其作用为：
1) Lubricate moving parts to minimize wear.2) Lubricate moving parts to minimize power lo from friction.3) Remove heat from engine parts by acting as a cooling agent.4) Absorb shocks between bearings and other engine parts, thus reducing engine noise and extending engine life.5) Form a good seal between piston rings and cylinder walls.6) Act as a cleaning agent, washing the working surfaces free of chemical deposits, dust and dirt to protect them from corrosion.1.润滑运动零件，减少磨损。
2.润滑运动零件，减少因摩擦引起的功率损耗。 3.起冷却剂作用，带走发动机零件产生的热量。
4.吸收轴承和其它发动机零件之间产生的冲击力，减少发动机的噪音，并延长其寿命。
5.在活塞环和气缸壁之间形成良好的密封。
6.起清洁剂作用，冲洗运动零件表面的化学杂质，灰尘和污物，以避免部件受到腐蚀。
A satisfactory engine lubricating oil must have certain characteristics, or properties.It must have proper viscosity (body and fluidity) and must resist oxidation, carbon formation, corrosion, rust, extreme preure, and foaming.Also, it must act as a good cleaning agent, must pour at low temperatures, and must have good viscosity at extremes of high and low temperature.理想的发动机润滑油必须具有某些特性：必须具有一定的粘性（粘稠度和流
30 动性），并且必须具有抗氧化、防止碳膜生成、防腐、防锈、抗极压和防泡沫等作用，润滑油必须具有良好清洁作用和良好的低温流动性，以及在高温和低温时都具有良好的粘性。
Any mineral oil, by itself, does not have all these properties.Lubricating-oil manufacturers therefore put a number of additives into the oil during the manufacturing proce.An oil for severe service may have many additives, as follows: (1) usually a viscosity-index improver; (2) pour-point depreants; (3) oxidation inhibitors; (4) corrosion inhibitors; (5) rust inhibitors; (6) foam inhibitors; (7) detergent-dispersants; (8) extreme-preure agents.任何矿物油自身都不具备所有这些特性。因此，润滑油厂家在制造润滑油的过程中，加入了许多添加剂。高级润滑油中可能加入以下这些添加剂：（1）常常加入黏度指数添加剂；（2）抗凝剂；（3）抗氧剂；（4）防腐剂；（5）防锈剂；（6）抗泡剂；（7）净化分散剂；（8）极压剂。
Words and Expreions agent：（化学）剂；oxidation：氧化；additive：添加的，添加物；improver：促进剂；depreant：抑制剂（添加剂）；inhibitor：抑制剂，防腐剂；detergent：净化剂，去垢剂；dispersant：分散剂；splash lubricating：飞溅式润滑；combination splash and preure feed lubricating：飞溅压力结合式润滑；valve：气门机构；cleaning agent：清洁剂；chemical deposits：化学沉淀。 31
11.Engine Cooling System
发动机冷却系统
The purpose of the cooling system is to keep the engine at its most efficient operating temperature at all engine speeds and all driving conditions.冷却系统的作用是使发动机在各种转速和各种行驶状态下都能有效地控制温度。
A great deal of heat is produced in the engine by the burning of the air-fuel mixture.Some of this heat escapes from the engine through the exhaust gases (the host gases left after the gasoline is burned).But enough remains in the engine to cause serious trouble unle removed by some other means.The cooling system takes care of this additional heat.混合气的燃烧在发动机中产生大量的热，其中部分热量通过废气被排出。但是，残留在发动机中的余热仍足以使发动机受到严重损坏，除非用其它的方法排除这些余热。冷却系统就是专门用来消除余热的。
The cooling system is built into the engine.There are hollow spaces around each engine cylinder and combustion chamber.These hollow spaces are called water jackets, since they are filled with water.When the engine is running, the water takes heat from the engine, becoming hot in the proce.A water pump pumps the hot water from the engine water jackets into the radiator.The radiator has two sets of paages.One set carries water.The other set carries air (pulled through by car motion and engine fan).As the hot water paes through, it gives up its heat to the air paing through.The cooled water then reenters the engine, where it can pick up more heat.In operation, water continuously circulates between the engine and radiator, carrying heat from the engine to the radiator.By this means, exceive engine temperatures are prevented.冷却系统就设臵在发动机中。在每个气缸体和燃烧室周围都留有空腔。这些空腔装满了水，因此称之为水套。在发动机运行过程中水被加热，并以水循环方式把热量从发动机中带走。水泵从发动机水套中把热水抽到散热器中。散热器有两条通道：一条是水道，另一条是气道（空气是通过汽车行驶和发动机的风扇抽
32 入的）。当热水流过水道时，气道中流通的空气使热水冷却。冷却后的水又重新进入发动机，再把发动机中的热量传导出去。在这一过程中，水不断地在发动机与散热器之间循环，水携带着热量从发动机流到散热器再散发出去。通过这个方法可避免发动机温度过高。
Two general types of cooling systems are used, air cooling and liquid cooling.Most automotive engines now employ liquid cooling.The liquid cooling system consists of water pumps, water jackets, engine fan, radiator, and so on.The water pump, driven by a belt from the engine crankshaft, circulates the cooling liquid between the radiator and engine water jackets.The cooling liquid is water.Antifreeze compounds are added to the water during the winter.The water jacket is cast into the cylinder blocks and heads.The engine fan is usually mounted on the water pump shaft and is driven by the same belt that drives the pump and the generator.The purpose of the fan is to provide a powerful draft of air through the radiator.The radiator is a device for holding a large volume of water in close contact with a large volume of air so that heat will transfer from the water to the air.The radiator core is divided into two separate and intricate compartments; water paes through one, and air paes through the other.通常使用的冷却系统有两种形式：空气冷却系和液体冷却系。现在大多数汽车发动机都采用液体冷却系。液体冷却系由水泵、水套、发动机风扇、散热器等组成。水泵由发动机曲轴上的皮带驱动，使冷却液在散热器与发动机水套之间循环流动。冷却液是水。冬季在水中需加入防冻剂。水套被铸入气缸体和气缸盖内部。发动机风扇通常安装在水泵轴上，由驱动水泵和发电机的同一条皮带驱动。风扇的作用是向散热器提供强大的空气流，与大量空气密切接触的散热器内可以容纳大量的水，这样热量可以通过水散发到空气中。散热器芯为分离和间隔交错的两部分。冷却水在其中一部分流过，空气在另一部分中通过。 Words and Expreions radiator：散热器，水箱；antifreeze：防冻剂；compound：混合物；draught：气流；compartment：间隔。 33
14.Engine Ignition System
发动机点火系统
The ignition system is part of the electric system of the automobile.Its purpose is to produce high-voltage surges (up to 20,000 volts) and to deliver them to the combustion chambers in the engine.These high-voltage surges then cause electric sparks in the combustion chambers.The sparks ignite, or set fire to, the air-fuel mixture in the combustion chambers so that it burns and causes the engine to operate.点火系统是汽车电气系统的一部分。其作用是产生高达2万伏的高压电脉冲，并且将其输送到发动机的燃烧室。高压电脉冲在燃烧室中形成点火花，引燃燃烧室中的可燃混合气，使发动机运转。
The ignition system consists of three basic parts: the ignition distributor, the ignition coil, and the spark plug, together with the connecting wires.When the engine is turning, the ignition coil is repeated connected to and disconnected from the battery.Every time the coil is connected, it becomes loaded with electrical energy.Then, when it is disconnected, the ―load‖ of electrical energy is released in a high-voltage surge.This surge flows through the wiring to the spark plug in the engine cylinder that is ready to fire.You must understand that all this takes place very rapidly.At high speed, the whole series of events happens in le than one three-hundredth o a second.That is, there will be as many as 300 of these events every second that the engine is running at high speed.点火系统包括三个基本部分：点火分电器、点火线圈和火花塞，以及起连接作用的导线。当发动机转动时，点火线圈与蓄电池之间不断地连接和断开。每当线圈与蓄电池接通时，就会充载电荷，然而当线圈与蓄电池断开时，电荷以高压脉冲的方式释放出来，通过导线把高压电脉冲输送到待点火的发动机气缸上的火花塞上。你必须理解这一切发生得极其迅速。全部一系列动作以极高的速度发生在短短三百分之一秒内。也就是说，在发动机高速运转时，这样的动作每秒钟要发生三百次。
Some systems use transistors to reduce the load on the distributor contact points.Other systems do not have contact points but use instead a combination of transistors
34 and a magnetic pick-up in the distributor.有些点火系统使用晶体管来减少分电器触点的负荷。这种点火系统没有触点，而是在分电器中使用晶体管与磁传感器。
The ignition distributor has two jobs.First, it closes and opens the circuit between the battery and ignition coil.The distributor’s second job is to distribute each high voltage surge to the correct spark plug at the correct instant by means of the distributor rotor and cap and secondary wiring.点火系统的分电器有两个作用。首先，负责接通和关闭蓄电池和点火线圈之间的电路。分电器的第二个作用是通过分火头、旁电极和辅助线路，将高压电流准时地分配给相应的火花塞。
There are two basic types of distributor: (1) the type using contact points to close and open the coil primary circuit; (2) the type using a magnetic pick-up and a transistor control unit to interrupt the current flow of the coil primary circuit.分电器有两种基本形式：一种是使用触点关闭和接通初级线圈的电流，另一种使用磁传感器和晶体管控制装臵来切断初级线圈的电流。
Words and Expreions voltage：电压，伏特数；surge：冲击；disconnect：分离，断开；the electric system：电气系统；ignition distributor：点火分电器；ignition coil：点火线圈；spark plug：火花塞；high-voltage surge：高压电脉冲；magnetic pick-up：电磁传感器；contact point：触点；the coil primary circuit：初级线圈；transistor control unit：晶体管控制装臵；distributor rotor and cap：分电器分火头和旁电极；secondary wiring：次级线圈，辅助线路。 35
15.Engine Starting System
发动机起动系统
Automobile engines are not self-starts.In order to start them, the engine crankshaft must be turned over by some outside means so as to (a) admit air-fuel mixture to the cylinder, and (b) cause the mixture to fire.汽车发动机是不能自行启动的。为了启动发动机，发动机曲轴必须借助外界的手段转动起来，这样：（1）使可燃混合气进入气缸，（2）是可燃混合气点火。
In the case of automobile engines, the mixture in the cylinder, after being compreed, must be not enough to ignite.This requires that the engine be turned over with sufficient speed.If the engine is turned over too slowly, the unavoidable small leaks past the piston rings and also through the intake the exhaust valves of four-cycle engines will permit a substantial part of the fuel-air mixture to escape during the compreion stroke.Also, the heat lo from the compreed air to the cylinder walls will be greater at low speed because of the longer exposure.The escape of air and the lo of heat both result in a lower temperature at the end of compreion.Therefore, there is a minimum speed which the engine must attain before ignition will occur and the engine will begin firing.The starting speed depends upon the type and size of the engine, its condition, and the temperature of the air entering the engine.对于汽车发动机来说，气缸中的可燃混合气被压缩后，必须有足够的热量才能被点燃。这就要求发动机达到足够高的转速。如果发动机转速太慢，四行程发动机的活塞环和进排气门就不可避免地有泄漏现象，这会使大量的可燃混合气在压缩行程期间泄漏掉。此外，发动机在低速时，由于接触时间较长，压缩气体传给气缸壁的热量较大。在压缩过程结束，温度较低的情况下，会产生漏气和热损失两种现象。所以，发动机在引燃和开始点火前，必须达到一个最低转速。启动转速取决于发动机的型号、大小和状态以及进入发动机的空气的温度。
The starting system contains a cranking, or starting, motor, and other acceories.起动系统包括起动机和其它附件。
The starting motor electrically cranks the engine for starting.It is a special 36 direct-current motor operating on battery voltage and is mounted on the engine flywheel house.The starter changes the electrical current into the mechanical energy to push the crank-shaft round.By means of this, the engine can be started.The cranking motor consists of the commutator end head, holding the brushes; the field frame, into which the field windings are aembled around pole shoes; the drive housing, which houses the drive aembly the supports the motor on the engine flywheel housing; the armature; and the drive aembly.Some cranking motors also have a solenoid that operates the shift lever.起动电机用电能来启动发动机。起动电机是以蓄电池为动力来源的直流电机，它安装在发动机的飞轮壳上。起动电机把电流转换为机械能，驱动曲轴转动，并带动发动机运转。起动电机由固定电刷的换向器头、磁场框架、传动箱、电枢以及传动总成等组成，在磁场框架中，励磁线圈内套着电枢；传动箱内装有传动总成，并且支承固定在发动机飞轮壳上的电动机。有些起动电机还有一线圈来带动操纵杆。
Cranking-motor controls have varied from a simple foot-operated pedal to automatic devices that close the cranking-motor circuit when the accelerator pedal is depreed.控制起动电机的方式已从一个简单的脚踏板改为压下加速踏板即可自动接通起动电机电路的自动装臵。
The present system that has been almost universally adopted for paenger cars and many other vehicles has starting contacts in the ignition switch.When the ignition key is turned against spring preure past the ON position to START, the starting contacts close.This connects the cranking-motor solenoid or magnetic switch to the battery.After the engine starts and the ignition key is released, spring preure returns it to the ON position.The starting motor should not be operated more than 5 seconds during each starting operating, for the sake of recovering the energy of battery.It will not be allowed to start it again until it’s stopped for fifteen second.
轿车和其它许多类型的车辆已普遍采用点火开关装臵。起动接触器装在点火开关上。转动点火钥匙，弹簧的压力使“开启”位臵变为“启动”位臵，启动接 37 触器闭合，使得启动电机线圈或磁性开关与电池接通。发动机启动以后，点火钥匙回转，在弹簧的压力下，恢复到“开启”位臵。起动电机每次启动过程的时间限定在5秒钟以内，以便使电池的能量及时得到补充。15秒后方可再次启动。
Words and Expreions acceory：附件；commutator：换向器；brush：电刷；armature：电枢；solenoid：螺丝管；cranking motor：起动电机；foot-operated pedal：脚踏板；for the sake of：为了…起见；direct-current motor：直流电机；flywheel house：飞轮壳；commutator end head：换向器端头；the field frame：磁场框架；field windings：励磁线圈；pole shoes：电枢；drive housing：传动箱；the drive aembly：传动总成；shift lever：换档操纵杆；accelerator pedal：加速器踏板；starting contact：启动触点器。 38
14.Locomotives 1.Steam Locomotive 1.蒸汽机车
The speed of railways, which transformed life in the nineteenth century, is linked inextricably with the steam locomotive.To its devotees the steam locomotive was one of the most romantic and beautiful machines ever built.It first appeared in 1804 in a simple version invented by an Englishman Richard Trevithick.19世纪改变了人们生活的铁路的飞速发展与蒸汽机车密不可分。对其热爱者来说，蒸汽机车是有史以来建造的最具罗曼蒂克最漂亮的机器。最早的蒸汽机车出现于1804年，是由英国人Richard Trevithick发明的一个简单版本。
The first steam locomotives to do useful work were ordered and used by coal mines in northeast England in 1813-20.in 1825 a public railway was opened between the English towns of Stockton and Darlington.It had been planned for horse traction, but George Stephenson (1781-1848), a leading builder of colliery locomotives, persuaded the directors to operate a steam locomotive hauling trains heavier than horses could manage.The succe of this line led to the much bigger and more important railway between Liverpool and Manchester.It was opened in 1830 after bitter opposition from landlords, coachmen, canal bargees and the large sector of the population that abhorred any change and considered smoke-spouting locomotives to be engines of Satan.Against spirited competition, Stephenson’s Rocket was chosen to provide the motive power.It was small and light enough to run on only four wheel without breaking the flimsy iron track.Thanks to steady improvements in manufacturing, it became poible to make boilers stronger, cylinders and pistons more accurate and better fitting, and the whole locomotive capable of developing more power at higher speeds.将蒸汽机车最早用于作有用功是在1813-1820年英格兰东北部的煤矿上。
39 1825年，英国的Stockton 镇和Darlington镇之间开通了一条公共铁路。这条路本来的设计是使用马匹来牵引，但是一位煤矿机车的主要建造者George Stephenson (1781-1848)说服了领导者采用蒸汽机车来牵引列车，这比马能牵引的要重的多。这条线路的成功导致了利物浦和曼彻斯特之间的更大更重要的铁路的问世。这条铁路开通于1830年，之前受到了来自地主、马车夫、运河船员和那些憎恨任何变化并将喷出烟雾的机车视作魔鬼机器的大范围人口的强烈反对。经过激烈的竞争，斯蒂芬孙的Rocket被选作动力的提供者。该机车又小又轻，仅有四个轮子，这样才不至于破坏脆弱的铁轨。由于制造方面的稳步发展，逐渐变得可以制造更坚固的锅炉，气缸和活塞的制造也更精确、相配更好，机车整体也有能力在更高的速度下产生更大的功率。
For a century steam locomotives provided nearly all the traction for the world’s railways.There were no dramatic technical advances but size, power and speed grew constantly.In Europe many rail systems used excellent track, capable of bearing 100 tonne locomotives running at up to 160km/h (100mph).But in the United States in early days, and in most other young, developing countries, track was lighter, and often badly laid by men racing to complete more miles each day.This called for more wheels to spread the load.Speeds were limited and seldom exceeded 80km/h (500mph), apart from one or two short record-setting runs.在整个世纪内，对世界上的铁路而言，其牵引几乎都由蒸汽机车提供。除了体积、功率和速度不断提升之外没有什么大的变化。在欧洲，许多铁路系统都采用非常优良的铁轨，可以承载100吨的机车以高达160千米/小时（每小时100英里）的速度运行。但是在早期的美国以及大多数年轻的发展中国家，铁轨的承载能力较小，而且人们通常为了比赛每天完成更多英里的铺设这些铁轨通常铺得很差。这就需要更多的轮子来分散负载。车速因此受到限制，除了极个别短暂的破纪录运行之外，很少有超过80千米/小时（每小时50英里）的。
The steam locomotive has reached its zenith by the 1930s.European ―steamers‖ were clean, splendidly painted in the livery of their operating companies and, when designed for expre paenger haulage, often capable of reaching 160km/h (100mph).
40 American locomotives tended to be more utilitarian.Demands for greater power led to increases in size until they became the biggest land vehicles in history.蒸汽机车的发展于20世纪30年代之前达到了顶峰。欧洲的蒸汽机车整洁华丽，描绘着所在公司的图案，在被设计用于快速客运时速度常常可达到160千米/小时（每小时100英里）。美国机车则趋向于更功利化。对更大功率的要求导致了体积的增长直到它们变成了有史以来最大的陆上运输工具。 2.Electric Locomotive 2.电力机车
The first rival to steam came in the form of the direct-current electric motor, adopted in cities (especially in underground railways), to avoid smoke pollution.The first electric train ran at an exhibition in Berlin in 1879.Soon countries such as Switzerland and Norway found that it was cheaper, with the development of hydroelectric power, to generate electricity than to burn brown coal or wood, and their networks became all electric.
蒸汽机车最早的对手是主要用于城市中（尤其是地下铁路），为了避免烟气污染的直流电力马达机车。最早的电力火车是1879年在柏林作为展示运行的。很快一些国家诸如瑞士和挪威发现随着水力发电的发展，发电要比燃烧褐煤或木材要便宜，因此它们的铁路网络很快全都变成了电力的。
Today the electric motor with its linear form under development, is regarded as the best from of traction for railways but the huge capital costs impede its introduction except on the busiest routes.As long ago as 1955, French Railways demonstrated that electric trains of conventional type could run at more than 320km/h (200mph), but average speeds of public trains have risen only slowly.The Japanese New Tokaido line achieved a sudden jump in speed because the line was laid for high speed.Even so , track and trains need constant maintenance. 41 现在电力马达及由其发展出的一次形式，以被认为是铁路牵引最好的形式，但是除了在一些繁忙的线路上，它的引入因为巨大的投资而受到了限制。早在1955年，法国铁路公司就证明常规式的电气化列车可在320千米/小时（每小时200英里）以上车速下运行，但普通列车的平均车速仍增长缓慢。而在日本新干线上，由于线路适用于高速，因此车速得到了迅猛提高。尽管如此，轨道和列车都需要定期的维修。 3.Diesel Locomotive 3.内燃机车
About 1920, the first diesel locomotives and railcars came into general use, powered by compreion-ignition oil engines developed by the German Rudolph Diesel (1858-1913)。Though often noisy, diesel engines pick up speed faster and convert 25 to 45 per cent of their fuel energy into useful haulage, whereas the fuel efficiency of steam traction seldom exceeded eight per cent.Despite greater capital cost, diesel locomotives gradually ousted steam from 1935 onwards, until today steam engines are confined to a shrinking number of railways in Africa and Asia and a few local lines elsewhere.Diesels can be started and stopped easily, burn no fuel when not working, and can run at close to maximum power for hours at a time with no strain on either machines or crew.Many diesel locomotives run more than 160 000 km (100 000 miles) a year and modern examples are highly reliable, versatile and relatively efficient, as well as being fast.
大约在1920年，最早的内燃机车和铁路车辆投入广泛的运行，其动力由德国人鲁道夫改进的压缩点火的燃油发动机提供。尽管通常噪声很大，但是内燃机车加速较快，而且可以将燃料能量的25%到45%转变成有用的牵引力，而蒸汽机车的燃料转化效率则很少有超过8%的。尽管内燃机车投资较大，但还是从1935年起逐步取代了蒸汽机车，到目前蒸汽机车的应用已越来越少，只限于非洲、亚洲的部分铁路和其他地方的一些市郊线上。内燃机车的启动和停车都很容易，在不工作时不会消耗燃料，而且有时还可以数小时保持接近最大功率运行而不会对
42 机器和乘务人员造成损伤。许多内燃机车每年可以运行160000千米（100000英里）以上，现代的内燃机车不仅高速，而且有高度的可靠性、适用性和较高的效率。
Only in the smallest sizes does the diesel engine drive the wheels through a mechanical gearbox, as on a lorry.Generally the two are linked hydraulically or electrically.Hydraulic transmiions are arrangements of turbines linked by oil under high preure, and they can transmit smoothly 2 000 horsepower with any ratio between input and output speeds.In the diesel-electric locomotives the engine drives a generator or alternator.This is used to supply current to traction motors similar to those of electric locomotives.除了像载重卡车中的这种小型柴油机是通过机械变速箱来驱动车轮的以外，一般情况下柴油机与车轮之间都是利用液压或电力来传动的。液压传动通过设臵由高压油驱动的涡轮来实现，液压传动可以在输入与输出速度之间为任意传动比时平稳的传输2000马力的功率。在柴油发电机机车中，用发动机来驱动发电机或交流发电机。同电力机车中相似，这被用来向牵引马达供给电流。
43
15.Diesel Traction
内燃牵引
We have now to consider the characteristics of the diesel engine, and the way in which it is used in railway traction.As we saw earlier, in an engine of this type the high temperature needed to ignite the fuel is produced by the piston, which comprees the air in the cylinder to between 650 and 850 lb.per sq.in., raising its temperature to between 1,500 and 1,800 degrees Fahr.When the maximum compreion has been reached, the oil, at a preure of from 2,000 to as much as 5,000 lb.per sq.in., is injected in the form of a finely divided spray, and ignites with explosive force, diving the piston backwards under a preure of 850 to 1,000 lb.per sq.in..Injection continues for long enough during the piston stroke to ensure that combustion and the preure on the piston correspondingly even.我们现在考虑一下柴油机的特性及其用于铁路牵引的方式是很有必要的。正如我们在前面看到的，这类发动机燃油点火所需要的高温是由活塞产生的，活塞在气缸内将空气压缩，使压力达到650磅/平方英寸到850磅/平方英寸，温度升高到华氏1500度到1800度。当压力达到最大限度时，燃油的压力达到2000磅/平方英寸甚至高达5000磅/平方英寸，呈细雾状喷射进气缸并点火，产生爆炸力，以850-1000磅/平方英寸的压力推动活塞向下运行。在这个活塞冲程内，燃油继续喷射，以保证燃烧继续进行并使对活塞的压力相应地均匀。
Many modern diesel engines are ―supercharged‖ by an increase in the preure of the air before it is paed into the cylinders.The most common application is by the turbo-supercharger, in which the exhaust gases from the cylinder drive a gas turbine coupled to an air-compreor.The latter fills the cylinder with air at from 147 to 22 lb.per sq.in.above atmospheric preure, and this high preure encourages a proportionately greater consumption of fuel, so boosting the power output by as much as 50 per cent.一些现代的柴油机是增压的，在空气进入气缸之前就增加其压力。最常采用的是涡轮增压器，由气缸排出的废气驱动燃气轮机，并带动连接在一起的空气压缩机。由空气压缩机以超过大气压17-22磅/平方英寸的压力将空气压入气缸。 44 这样高的压强，促使燃油消耗量相应地增多，因而提高柴油机的输出功率，差不多提高50%。
In Great Britain the type of diesel engine in most common use is the four-stoke.The first stoke of the piston comprees the air; just before the end of it the fuel is injected and combustion begins, continuing during the return stroke; the third stroke is the one during which the cylinder is ―scavenged‖ of its spent gases; and in the fourth stroke-that is, the second return stroke-the exhaust port closes, and the inlet valve is opened to admit the air for the next compreion stroke.在英国最常使用的柴油机是四冲程的。第一活塞冲程是压缩空气：正好在此冲程结束之前进行喷油和开始燃烧，并在活塞回程中（即第二冲程）继续进行；第三冲程排出气缸内已用过的废气；在第四冲程中，活塞第二次回程，排气孔关闭，进气阀打开以吸入空气，为下个压缩冲程做准备。
It is during one stroke only out of the four, the second, that the engine develops its power, and this is why the diesel engine requires a number of cylinders, from four in a small shunter to sixteen or more in a main unit of high power, with their cranks set at angles which divide up the circle into a corresponding number of equal parts, so ensuring a perfectly even torque of the crankshaft.In the V-type cylinder arrangement, often adopted in the larger diesel engines, setting the cylinders alternately at an angle right or left the centre-line, in a ―V‖ formation, makes poible a reduction in total length as compared with an engine that has all the cylinders in line.柴油机在四个冲程中，只有一个冲程即第二个冲程产生功率，这就是为什么柴油机需要有若干个气缸，其数目从用于小功率调车机车的4缸，到用于大功率干线机车的16缸或16缸以上。各个气缸的曲柄互相排列成一定的角度，把柴油机工作周期划分为相应数目的相等部分，这样就保证了曲轴的扭矩十分均匀。较大功率的柴油机的气缸往往按V型排列，气缸在中线的左侧或右侧，以一定角度交错安排，气缸以V型排列的柴油机比全部气缸单列的柴油机更能缩短其总长度。
There is also the two-stroke engine, in which the cycle of operation is completed in a single return stroke of the piston.Near the end of the combustion stroke the 45 piston uncovers an exhaust port, which allows the spent gases to escape, and a further piston movement uncovers the inlet port, through which a charge of air under preure enters the cylinder behind the piston.As soon as the piston has paed the two ports on return stroke compreion begins, and the oil is injected just before the piston reaches the top of the stroke.The power of a two-stroke engine does not go up in proportion to the fact that combustion takes place on every return stroke of the piston, instead of on every alternate return stroke, because the two stroke engine is le efficient than the four-stroke.也有两冲程的柴油发动机，它的工作循环仅由活塞用一个来回的行程就完成了。当接近燃烧冲程的末端时，活塞打开一个排气孔，让已用过的废气排出去，活塞再进一步运动，打开进气孔，空气通过进气孔随着活塞在压力下进入气缸。一旦活塞在回程中通过了这两个气孔，就开始压缩空气，刚好在活塞到达上止点之前，喷射燃油。两冲程发动机的活塞每次回程都产生燃烧，不像四冲程活塞每隔一次回程才产生燃烧，但其功率并不是按比例增大，因为两冲程发动机的效率比四冲程的效率要低。
Of the complicated equipment of a diesel engine, the most important constituent-in effect, the nerve centre is the fuel injection pump.It is driven off the main crankshaft by a series of cams on an independent shaft, and each cam actuates the plunger of one of the cylinders.This plunger traps a small quantity of fuel oil, and delivers it as fine spray into the cylinders above the piston, after which a spring restores the plunger to its out-of-action position.The amount of fuel delivered per stroke can be varied, with a proportionate variation in the power developed by the engine.In a two-stroke engine the camshaft is rotated at the same speed as the main crankshaft, and in a four-stroke engine at half the speed.Another camshaft works the valves which open and close the cylinder ports at precisely the right moments.Correct timing is of the utmost importance, and also extreme accuracy, down to a twenty-thousandth part of an inch, in the grinding of certain parts of the fuel injection pump and the valves.在柴油机的复杂设备中，实际上最重要的组成部分的核心部分是喷油泵。它是由主轴通过独立轴上的一系列凸轮驱动的，每个凸轮推动一个气缸喷油泵的柱
46 塞，该柱塞封住少量的燃油，并以细雾状射入气缸活塞上方，然后喷油泵的弹簧使柱塞回到“停止”位臵。每个冲程喷射燃油的数量可以变化，这就使发动机产生的功率发生相应的变化。两冲程发动机的凸轮轴旋转速度与主轴旋转速度相同，而四冲程发动机则为主轴转速的一半。另外有一根凸轮轴控制气阀，它准确、及时地打开与关闭气缸的进气气孔。校正定时的工作是极其重要的，而准确的精密度也是极其重要的，对喷油泵与气阀某些部件的研磨精密度可达到两万分之一英寸。
The cylinders of a diesel engine would become dangerously overheated if effective measures were not taken to cool them.Each cylinder therefore is encased in a water jacket, which forms part of a circuit through which water is pumped continuously, and cooled by means of air drawn in from the outside atmosphere by large rotary fans, worked off the main crankshaft, or, in the larger diesel-electric locomotives, by auxiliary motors.The fans are often fitted with movable shutters to their air intakes, which open and close automatically, under the control of thermostats, to keep the cylinder temperatures as even as poible, admitting more air when the engine is working hard, and le when it is idling.A second cooling circuit is needed for the lubricating oil, of which a considerable amount is used, and a third, in the case of a diesel-electric locomotive, as with a straight electric locomotive, to prevent overheating in the generators and traction motors.如果不采取有效的冷却措施，柴油机的气缸变得过热就会产生危险。因此每个气缸都围着一个水套，水套形成循环水路的一部分，由水泵驱使水在回路中不断地流动，并由大型旋转风扇从外部鼓入空气使水冷却。大型旋转风扇是由主轴带动的，而在大型电力传动内燃机车上则由辅助电动机来带动。在风扇的空气入口处，通常装有带活动叶片的百叶窗，叶片受恒温器控制能自动地开闭，以保持气缸温度尽可能稳定。当发动机加大负荷工作时，进来的空气就多些，而在发动机空转时，进来的空气就少些。由于使用大量的润滑油，需要有第二条冷却回路。而电力传动内燃机车，与电力机车一样，需要第三条冷却回路，以防止发电机和牵引电动机过热。
Special measures are neceary for starting up a diesel engine, seeing that no combustion of the fuel can take place without initial air compreion in the cylinder.
47 In the smaller diesels this can be done by hand cranking, or by the use of compreed air, or by a device similar to the self-starter of a motor-car, supplied with current from batteries.In a diesel-electric locomotive, however, the general practice is to use current from the storage batteries to drive the generator as though it were a motor, so completely reversing its function; a few moments usually suffice to work the engine by means of the main crankshaft until combustion begins.After this the engine is idled until the locomotive is required to start.柴油机起动必须有专门的措施，因为如果气缸内没有初始的压缩空气，燃油就无法产生燃烧。小型柴油机的起动可以用手摇曲柄或用压缩的空气，或用与汽车上的自动起动器等类似的装臵，由蓄电池供电，而电力传动内燃机车一般习惯用蓄电池的电流驱动发电机，就好像该发电机是电动机一样，把它的功能完全倒转过来。依靠主曲轴驱动发动机使气缸内开始燃烧，只需要一会儿的时间，在此以后直至机车需要起动之前，发动机是在空转。
Transmiion of power from the diesel engine to the locomotive axles is a simple matter in the smaller diesels.In low-powered railcars and shunters, up to, say, 250 or 300 h.p., a gearbox similar to that of a road motor-car serves the purpose, with a gear selector, a forward and reverse lever, a clutch and accelerator for control.To enable the drive to be taken up smoothly, some form of fluid coupling is often inserted between the engine and the gearbox.Diesel-mechanical transmiions may include as many as eight speeds, both forward and reverse.在小型内燃机车内，柴油机把动力传给机车动轴的传动只是个简单的问题。在小功率，譬如在250-300马力以下的铁路动车和调车机车上，可以用一种类似汽车使用的变速箱来达到这个目的，它带有一个齿轮选择器，一个前进与后退的推杆、一个离合器和一个控制加速器。有些机车常用液力耦合器装在发动机与变速箱之间，这样就能平稳地进行传动。机械传动的内燃机车的调速可以多达八级，既能前进也能后退。
There is a limit, however, to the range of power which can be transmitted mechanically, and this was the reason why electricity was chosen, at a relatively early date, as the intermediary between diesel engine and rail in the more powerful diesel locomotives.In a diesel-electric locomotive plant the diesel engine dries an electric
48 generator, normally mounted on the same bedplate, and it is customary for an auxiliary generator to provide for charging the batteries, lighting and electric control.The d.c.current from the main generator drives the traction motors, mounted on the axles in most modern diesel-electric locomotive, and this part of the equipment is exactly the same as that of the electric locomotives.In a diesel locomotive, while an electric transmiion is ideal so far as finene of control is concerned, it adds greatly to the weight, the cost and the complication of the locomotive as a whole.但是，机械传动的功率范围是受到限制的，由于这个原因，大功率的铁路内燃机车在较早的时候就选择电力传动，作为柴油机和轨道之间的中间环节。电力驱动内燃机车上由柴油机驱动一台通常装在同一底板上的发电机。一般还有一台辅助发电机给蓄电池充电，并提供照明与电力控制用电。大多数现代的电力传动内燃机车，用主发电机发出的直流电来驱动安装于机车轴上的牵引电动机，这部分设备与电力机车的完全相同。尽管内燃机车的电力传动装臵就控制的灵敏度而言是完善的，但就整体而言，它大大地增加了机车的重量、成本和复杂性。
In recent years, however, such advances have been made in the design of hydraulic transmiions that they are being used succefully in diesel locomotives of up to 2,000 h.p..The core of a hydraulic transmiion is what is known as a ―fluid flywheel‖.This comprises, first, a driving member, which is a circular chamber fitted with vanes somewhat resembling those of a turbine, and filled with lubricating oil; and, second, the driven member, similarly provided with vanes and driving the output shaft.可是近几年来，液力传动装臵的设计制造亦有很大的进展，现在正成功地应用在功率高达2000马力的内燃机车上。液力传动装臵的核心通常称为“液力飞轮”，它首先包括主动轮，这是一个圆形壳体，装有叶片，有点像涡轮的叶片，并充满润滑油；其次是从动轮，它同样装有叶片，并驱动输出轴。
Rotation of the vanes of the driving member causes the oil to exert centrifugal preure against those of the driven member, which rotate at increasing speed until the two, in effect, are locked as one, although the speed of the latter, because of friction, is always very slightly le than that of the former.There is no wear and tear in a fluid flywheel comparable to that in a clutch, and the former has the advantage also that if
49 any seizure should take place, say in the engine, no serious damage is likely to result, because the oil preure in the chamber would break down.The diesel-hydraulic locomotive in future is likely to prove a serious rival to the diesel-electric, and hydraulic transmiions also are being used increasingly in diesel railcar power plants.主动轮的叶片旋转使油产生离心力，冲击从动轮的叶片，使从动轮的叶片旋转速度不断增加，直到最终咬合成一个整体，但由于摩擦的关系，后者的速度总是比前者稍微低一些。一个液力飞轮装臵与一个离合器比较起来，简直可以说没有磨损；同时它还有下述优点：即如果在传动中卡住，由于在壳体内油的压力会衰减下来，柴油机也不致受到很大的损害。将来液力传动内燃机车很可能成为电力传动内燃机车的重要竞争对手，液力传动装臵将越来越广泛地应用在铁路内燃动车的动力装臵中。
Words and Expreions diesel engine：柴油机；lb.(pound)：磅；sq.in.(square inch)：平方英寸；Fahr.(Fahrenheit)：华氏温标；supercharge：增压；scavenge：扫除，清除；main line unit：干线机车；shunter：调车机车；fuel injection pump：喷油泵；plunger：柱塞；grind：研磨；shutter：百叶窗；idle：空转；traction motor：牵引电机；hand cranking：手摇起动；railcar：动车；gear selector：变档杆；forward and reverse lever：前进及倒车控制杆；gearbox：变速箱；clutch：离合器；hydraulic transmiion：液传动；diesel-electric locomotive：电传动内燃机车；bedplate：底盘；charging：充电；vane：叶片；power plant：发动机组；coupled to：联结到。 50
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