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汽车英语-发动机部分(个人整理版)作者:fiat0012008-12-15 13:16 星期一 晴第一部分 发动机一、汽车发动机 Automobile Engines内燃机发动机是通过汽油和空气的混合而运行的,理想的空燃比是14.7份质量的空气和1份质量的汽油混合。Internal combustion gasoline engines run on a mixture of gasoline and air. The ideal mixture is 14.7 parts air to one part of gasoline(by weight.)由于汽油比空气重得多,因此我们一直笼统地说成大量的空气和少量的燃油。Since gas weights much more than air, we are talking about a whole lot of air and tiny bit of gas.当发动机点火后,一份被完全汽化的燃油和14.7份质量的空气混合,就能产生出巨大的动力。One part of gas that is completely vaporized into 14.7 parts of air can produce tremendous power when ignited inside an engine.让我们来看一下现代发动机的工作原理。Lets see how the modern engine uses that energy to make the wheels turn.空气通过空气滤清器进入发动机,并进入节气门。Air enters the engine through the air cleaner and proceeds to the throttle plate.通过油门踏板,你能控制经过节气门进入发动机的空气量。空气然后通过进气歧管进入各个气缸。根据不同的发动机类型,在空气滤清器后的某个部件,燃油通过燃料喷射系统或化油器(在老型号的汽车里)加入到气流中。You control the amount of air that passes through the throttle plate and into the engine with the gas pedal. It is then distributed through a series of passages called the intake manifold, to each cylinder. At some point after the air cleaner, depending on the engine, fuel is added to the air-stream by either a fuel injection system or, in older vehicles, by the carburetor.现代汽车的发动机大多数是四冲程的、火花塞点火。The majority of engines in motor vehicles today are four-stroke, spark-ignition internal combustion engines.一、 发动机类型发动机可以根据以下几种方法进行分类:工作循环方式;活塞做功方式;活塞链接方式;气缸布置形式;燃油喷射方法;速度。The engines can be classified in the following several ways: operating cycle; piston action; piston connection; cylinder arrangement; method of fuel injection, and speed.1、 工作循环方式 operating cycle根据每一次工作循环活塞运动的行程数,柴油发动机和汽油发动机可以分为两种类型,四冲程或者两冲程。发动机完成一个工作循环,需要四个行程,就称为四冲程循环发动机,或者简称四冲程发动机。如果发动机完成一个工作循环,只需要两个行程,就称为两冲程循环发动机,或者简称两冲程发动机。这样说来,两冲程发动机的点火次数是四冲程发动机的两倍。Diesel and gas-burning engines can be divided into two groups based on the number of piston strokes per cycle, either four or two. An engine which needs four strokes t complete one cycle is four-stroke cycle engine or, for short, a four-cycle engine. If it needs only two strokes to complete a cycle, it is called a two-stroke cycle engine or, for short, a two-cycle engine. Thus, a two-cycle engine fires twice as often as a four-cycle engine.2、 活塞做功方式 piston action发动机活塞的做功方式可以分为单向、双向、对置。An engines piston action may be classified as single-action, double-action, or opposed-piston.单向做功的发动机只利用气缸的一端以及依靠活塞的一个面提供动力。工作区域是在远离曲轴的那一端,也就是说,在一台垂直的发动机的上端。Single-acting engines use only one and end of the cylinder and one face of the piston to develop power. This working space is at the end away from the crankshaft, that is, at the upper end of a vertical engine.双向做功的发动机在上升和下降的冲程时,同时利用气缸的两端以及依靠活塞的两个面提供动力,其结构是相当复杂的,因此,双向做功的发动机只适用于大型和相对低速的结构中,比如说,提供内燃机船的动力。Double-acting engine use both ends of the cylinder and both faces of the piston to develop power on the upstroke as well as on the down stroke. The construction is complicated; therefore, double-acting engines are built only in large and comparatively low-speed units, generally to power motor ships.对置式的发动机的每隔气缸中都有两个活塞沿相反方向运动。燃烧的空间位于气缸中部,在两个活塞之间。有两根曲轴;上面的活塞驱动一根,下面的活塞驱动另一根。要注意的是,每个活塞是单向做功的,也就是说,动力只有活塞的一个面提供。An opposed-piston engine has cylinders in each of which two pistons travel in opposite directions. The combustion space is in the middle of the cylinder between the pistons. There are two crankshafts; the upper pistons drive one, the lower pistons the other. Note that each piston is single-acting; that is, it develops power with only one face of the piston.3、 活塞连接方式 piston connection活塞与连杆上端的连接,既可以是直接连接(筒状活塞式),也可以是间接连接(十字头式)。The piston may be connected to the upper end of the connecting rod either directly (trunk piston type), or indirectly (crosshead type).在筒状活塞式的发动机中,活塞与连杆上端通过一个水平销子连接。这是最常见的一种结构。In trunk-piston engines, a horizontal pin within the piston is encircled by the upper end of the connecting rod. This by far the most common construction.在十字头型发动机中,活塞连接在一根垂直的活塞杆上,活塞杆的下端又连接在一个叫做十字头的滑动构件上,十字头在导轨中上下滑动。十字头通过一个十字销与连杆上端连接。这种非常复杂的结构多用于双向做功的发动机。它也用在一些大型的、低速的、单向做功的发动机上。In crosshead-type engines, the piston fastens to a vertical piston rod whose lower end is attached to a sliding member called a crosshead, which slides up an down in guides. The crosshead carries a crosshead pin which is encircled by the upper end of the connecting rod. This more complicated construction is required in double-acting engines. It is also used in some large, slow-speed, single-acting engines.4、 气缸布置形式 cylinder arrangement柴油机和汽油机常见的气缸布置形式是:直列式、V型、水平式、径向式。The four basic cylinder arrangements of a diesel or gas-burning engine are: cylinder-in-line; V-arrangement; Flat, and radial.直列布置形式。这是一种最简单和最普通的布置形式,所有的气缸垂直的排列成一条线。这种结构,发动机最多用到12缸。发动机也制成水平的形式,常见的有一缸或者两缸,也有一些是三缸。A cylinder-in-line arrangement. This is the simplest and most common arrangement, with all cylinders arranged vertically in line. This construction is used for engines having up to 12 cylinders. Engines are also built with horizontal cylinders, usually one or two, in a few cases with three cylinders.如果发动机的气缸数超过八缸,就很难保证在曲轴也成直线布置的同时,制造出足够刚性的缸体。而且,发动机变得相当长,占据了相当多的空间。V形排列,由于每个曲柄销上有两根连杆,所以可使发动机的长度几乎缩短一半,这样就使发动机的刚性更大,曲轴也更坚固。这种形式只需要很少的维护工作,安装也方便。这在8缸,12缸,16缸发动机上是很常见的布置形式。气缸在被称作“箱体”的部件里排成一列,不同类型的箱体的角度是根据制造的需要而变化的,从30到120,大多数的角度是从40到75。(一个完成的循环是360)If an engine has more than eight cylinders, it becomes difficult to make a sufficiently rigid frame and crankshaft with an in-line arrangement. Also, the engine becomes quite long and takes up considerable space. The V-arrangement, with two connecting rods attached to each crankpin, permits reducing the engine length by almost one-half, thus making it much more rigid, with a stiff crankshaft. It also costs less to manufacture and install. This is a common arrangement for engines with eight, twelve, and sixteen cylinders. Cylinders lying in one line are called a “bank”, and the angle between the banks may vary, in manufacturing practice, from 30to 120, the most common angles being between 40and 75.(A complete circle is 360)水平布置的发动机是一种将箱体的角度增加到180的形式。这种气缸排列通常用在头部空间很小的机动车上,如货车、公共汽车以及有轨电车上。水平布置发动机也称“对置式”发动机。A flat engine is a V-engine with the angle between the banks increased to 180. This arrangement is used where there is little headroom, as in trucks, buses, and rail cars. Flat engines are also called “opposed-cylinder” engines.在径向式发动机里,所有的气缸都布置在一个圆圈里,而且都指向圆心。所有的活塞连杆都在同一个曲柄销上工作,绕着圆心旋转。这样以来,径向式发动机占据的空间很小。通过把连杆连接到包住曲柄销的一个主盘上,十二个气缸便可在同一个曲柄销上工作。In a radial engine all the cylinders are set in a circle and all point toward the center of the circle. The connecting rods of all the pistons work on a single crankpin, which rotates around the center of the circle. Such a radial engine occupies little floor space. By attaching the connecting rods to a master disk surrounding the crankpin, as many as twelve cylinders have been made to work on a single crankpin.5、 燃油喷射方法 method of fuel injection柴油机分为空气喷射发动机和固定喷射或者机械喷射发动机。空气喷射发动机利用一股高压气体将燃料吹到气缸内。空气喷射发动机在早期的柴油机上应用,但随着固体喷射系统的发展,空气喷射发动机已经被淘汰了。Diesel engines are divided into air-injection engines and solid or mechanical injection engines. Air-injection engines use a blast of highly compressed air to blow the fuel into the cylinder. Air injection was commonly use on early diesel engines but with the development of solid-injection systems the air-injection engine is rapidly disappearing.6、 速度 speed根据速度,柴油发动机和汽油发动机可以分为三个等级:低速、中速和高速发动机。All diesel and gas-burning engines may be divided into three classes according to speed; low-speed, medium-speed, and high-speed engines.汽车柴油发动机的速度一般高于1200转/分,但是有些发动机运转速度在3501200转/分之间,称作中速发动机。Automotive diesel engines often run faster than 1200 rpm, but the great majority of other engines run between 350 and 1200 rpm and are termed medium-speed engines.二、 发动机工作原理 How an Engine Works因为各气缸的工作行程是相同的,所以我们就从一个气缸了解四冲程是怎样运行的。Since the same process occurs in each cylinder, we will take a look at one cylinder to see how the four stroke process works.四行程是指进气行程、压缩行程、做功行程和排气行程。进气行程,活塞下行;压缩行程,活塞上行;做功行程,活塞下行;排气行程,活塞上行。The four strokes are intake, compression, power and exhaust. The piston travels down on the intake stroke, up on the compression stroke, down on the power stroke and up on the exhaust stroke.1、 进气行程 intake在进气行程,当活塞开始下行时,进气门打开,空气燃油的混合气被吸入气缸(类似于打开注射器的柱塞,将液体吸到针管内)。As the piston starts down on the intake stroke, the intake valve opens and the fuel-air mixture is drawn into the cylinder (similar to drawing back the plunger on a hypodermic needle to allow fluid to be drawn into the chamber).当活塞到达进气行程的下止点时,随着空气燃油的混合气进入气缸,进气门关闭。When the piston reaches the bottom of the intake stroke, the intake valve closes, trapping the air-fuel mixture in the cylinder.2、 压缩行程 compression活塞向上移动时,压缩在进气行程中吸入的混合气。混合气的压缩量,由发动机的压缩比决定。普通发动机的压缩比范围是8:1到10:1.The piston moves up and compresses the trapped air fuel mixture that was brought in by the intake stroke. The amount that the mixture is compressed is determined by the compression ratio of the engine. The compression ration on the average engine is in the range of 8:1 to 10:1.这意味着当活塞到达气缸上止点时,空气燃油混合气被压缩到原来体积的十分之一。This means that when the piston reaches the top of the cylinder, the air-fuel mixture is squeezed to about one tenth of its original volume.3、 作功行程 power火花塞点燃压缩的空气燃油混合气,燃烧使混合气迅速膨胀。其燃烧过程产生的巨大力量的推动着活塞向下运行,带动曲轴而产生推动汽车的动力。每隔活塞按不同的点火顺序依次点火。曲轴转两周,发动机里的气缸完成一个作功行程。The spark plug fires, igniting the compressed air-fuel mixture which produces a powerful expansion of the vapor. The combustion process pushes the piston down the cylinder with great force turning the crankshaft to provide the power to propel the vehicle. Each piston fires at a different time, determined by the engine firing order. By the time the crankshaft completes two revolutions, each cylinder in the engine will have gone through one power stroke.4、 排气行程 exhaust当活塞到达气缸的下止点时,排气门打开,燃烧后的废弃被推挤到排气系统。由于气缸内压力非常高,当气门打开时,废弃被一个巨大的推力排出(那就是为什么没有消声器的汽车噪音如此巨大的原因)。当活塞上升到达气缸上止点时,所有的废气被推出,排气门关闭以准备下一个四行程循环。With the piston at the bottom of the cylinder, the exhaust valve opens to allow the burned exhaust gas to be expelled to the exhaust system. Since the cylinder contains so much pressure, when the valve opens, the gas is expelled with a violent force (that is why a vehicle without a muffler sounds so loud.) The piston travels up to the top of the cylinder pushing all the exhaust out before closing the exhaust valve in preparation for starting the four stroke process over again.5、 机油系统 oiling system机油是发动机的生命之源。一台没有油的发动机就象一个没有血的人。机油通过一机油泵加压,流到发动机的各个运动部件。机油泵安装在发动机油底壳的底部,并且,通过一个齿轮与凸轮轴或曲轴连接。这样,当发动机运转时,油泵也开始工作。在油泵附近有个油压力传感器,它能检测油的压力并传递给警示灯或仪表板上的油量表。当你打开点火开关,在启动车子之前,油量警示灯亮,表明此时无油压力,同时也让你知道报警系统已开始工作。一旦发动机启动,报警系统就同时启动,此时警示灯熄灭,表明此时已有油压。Oil is the life-blood of the engine. An engine running without oil will last about as long as a human without blood. Oil pump is mounted at the bottom of the engine in the oil pan and is connected by a gear to either the crankshaft or the camshaft. This way, when the engine is turning, the oil pump is pumping. There is an oil pressure sensor near the oil pump that monitors pressure and sends this information to a warning light or a gauge on the dashboard. When you turn the ignition key on, but before you start the car, the oil light should light, indicating that there is no oil pressure yet, but also letting you know that the warning system is working. As soon as you start cranking the engine to start it, the light should go out indicating that there is oil pressure.6、 发动机冷却 engine cooling发动机必须保持一个恒定的工作温度,既不太热也不太冷。由于燃烧过程会产生大量热量,如果发动机无法自我冷却,那么发动机会严重损坏。发动机的主要部件变形从而导致漏水漏油,机油也会沸腾从而失效。Internal combustion engines must maintain a stable operating temperature, not too hot and not too cold. With the massive amounts of heat that is generated from the combustion process, if the engine did not have a method for cooling itself, it would quickly self-destruct. Major engine parts can warp causing oil and water leaks and the oil will boil and become useless.有些发动机采用空气冷却方式,大部分发动机采用液体冷却方式,水泵使冷却液在整个发动机形成循环,冷却液流至气缸和气缸盖周围发热的区域,然后水泵把热的冷却液抽到散热器中使之冷却下来。While some engines are air-cooled, the vast majority of engines are liquid cooled. The water pump circulates coolant throughout the engine, hitting the hot areas around the cylinders and heads and then sends the hot coolant to the radiator to be cooled off.三、 发动机元件 Engine Components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,并在气缸中压缩、点火、燃烧的。我们已知道燃烧产生高压,并推动活塞下行,带动曲轴传动。现在让我们详细研究一下发动机的各部分结构。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.1、 发动机气缸体 engine cylinder block水冷发动机的气缸体是发动机的基本构件。其他部件都支承或安装在他它上面。The 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.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。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.缸体不仅包括气缸,而且包括环绕的水套。The block contains not only the cylinders sleeves (also called bore liners) are used.在铝铸造的气缸中,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而产生的磨损。These metals have better wearing qualities than aluminum and can better withstand the wearing effect of the pistons and rings moving up and down in the cylinders.对于大部分发动机来说,铸铁是气缸壁的良好材料。而对于一些小型发动机,气缸壁面镀铬,铬是一种硬度非常高的金属,可减少气缸壁的磨损并延长使用寿命。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.2、 气缸盖 Cylinder Head气缸盖通常由铁、铁合金或铝合金整体铸成。铝兼有重量轻,导热性好的优点。也就是说,在其他因素一样时,铝盖更易冷却。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 lightness with high heat conductivity. That ism an aluminum head tends t run cooler, other factors being equal.气缸盖有两种: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体水套相连通。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。There are two types of head, L head and I head. Cylinder head contains water jackets for cooling in the assembled 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.3、 气缸体 Gaskets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。The joint between the cylinder block and the head must be tight and able to withstand the pressure and heat developed in the combustion chambers.机器加工并不能使气缸体和气缸盖平整光滑到严丝合缝。The block and head cannot be machined flat and smooth enough to provide an adequate seal.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。Thus, gaskets are used. Head gaskets are made of him sheets of soft metal or of asbestos and metal.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。密封垫也同样用于密封其他部件之间的结合处,例如,油底壳、歧管、水泵与气缸体之间的密封。All cylinder, water, valve, and bead-bolt openings are cut out. When the gasket is placed on the block and the head installed, tightening of the head bolts 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.4、 油盘(下曲轴箱 油底壳) Oil Pan油盘通常用的薄钢板冲压制成。依其不同的发动机,油盘的容量通常从5到10升不等。油盘和气缸体的下部一起被称为曲轴箱,用来封闭或罩住曲轴。润滑系统中的油泵把机油从油底壳中抽上来,输送到发动机的各个活动部件。机油再流下来回到油盘。这样,机油就在油盘和发动机的各个部件之间不断循环流动。The oil pan is usually formed of pressed steel. It usually holds 5 to 10 liters 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.5、 活塞 Piston实质上活塞是一个在气缸中上下移动的圆筒状的塞子。The piston is essentially a cylindrical plug that moves up and down in the engine cylinder.上面装有活塞环,从而使活塞和气缸壁之间具有良好的密封性。活塞由于燃气而发热,假如要使金属的温度保持在安全限度以内就必须散热。It is equipped with piston rings to provide a good seal between the cylinder wall and piston. The piston absorbs heat form the gas, and this heat must be carried away it the metal temperature is to be held within safe limits.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。The constant reversal of the piston travel sets up inertia tortes, which increase both with the weight of the piston and with its speed.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。For this reason, designers try to keep piston weight low, particularly in highspeed engines. As lower hood lines and oversquare engines became popular, the semi-slipper and full-slipper pistons came into use.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。On these pistons the number piston rings was reduced to three, two compression and one oil control.使用滑裙式活塞的原因是:短行程发动机需除去部分活塞裙部,从而为曲轴的平衡让出空间。滑动活塞长度较短,由于裙部被部分切除后而重量较轻。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。One reason for the slipper piston is that, on the short stroke, oversquare 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,

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