差速器和车桥课程毕业设计外文文献翻译/中英文翻译/外文翻译

     DIFFERENTIAL AND REAR AXLES The differential is part of the rear-axle-housing assembly,which includes the differential,rear axles,wheels,and bearing. If the car were to be driven in a straight line without having to make turns,then no differential would be necessary.However,when the car rounds a turn,the outer wheel must travel farther than the inner wheel.The differential permits the two rear wheels to rotate different amounts when the car goes around a turn , while still delivering power to both rear wheels. The rear axles are attached to the wheels and have bevel side gears on their inner ends.The differential case is assembled on the left axle but can rotate on a bearing independently of the axle.The differential case supports the differential-pinion gear on a shaft,and this gear meshes with the two bevel gears.The fing gear is attached to the differential case so that the case rotates with the fing gear when the latter is driven by the drive pinion. The driving power enters the differential through the drive pinion on the end of the propeller shaft.The drive pinion is meshed with a large ring gear so that the ring gear revoves with the pinion. Attached to the ring gear is a differential-pinion shaft on which are assembled two differential-pinion gears.Each rear car wheel has a separate axle, and there are two side gears splined to the inner ends of the two wheel axles.The two side gears.When the car is on a straighet road ,the two differential-pinion gears do not rotate on the pinion shaft ,but they do exert pressure on the two side gears turn at the same speed as the ring gear ,causing both rear wheels to turn at the same speed,also. When the car rounds a curve ,the outer wheel must turn faster than the inner wheel,To permit this,the two pinino gears rotate on their pinion shaft,transmitting more turning movement to the outer side gear that to the inner side gear.Thus,the side gear on the outer-wheel axle turns more rapidly than the side gear on the inner wheel axle.This permits the outer wheel to turn more rapidly while the car is rounding the curve. There are two basic types of axle:deed axles and live axle.The dead axle does not rotate; the wheel rotates on it.A common exmple is the axle on a horse-drawn wagon.Live axles are attached to the wheel so that both the wheel and the axle rotate together.Live axles are classified according to the manner in which they are supported:semifloating, three-quarer-floating,and full-floating.AUTOMOBILE  SYSTEM 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. 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. 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. A fuel pump delivers fuel from the tank to the carburetor. There are two general types of fuel pump, mechanical and electric. The fuel system has filters and 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. The carburetor is essentially a mixing device which mixes liquid gasoline with air. In this process, it throws a fine spray of gasoline into air passing through the carburetor on its way to the engine. The gasoline vaporizes and mixes with the air to form a highly combustion chambers, where it is ignited. It burns, causing the engine to produce power. The mixture must be of varying degrees of rich nice 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 to（ become less rich） for operation at intermediate speed with a worm engine. The carburetor has several different circuits, or passages, through which fuel and air-fuel mixture flow under different operating conditions to produce the varying richness of the air-fuel mixture. The purpose of the cooling system is to keep the engine at its most efficient operating temperature at all engine speeds and all drilling conditions. 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 hot gases left after the gasoline is burned） . But enough remains in the engine to cause serious trouble unless removed by some other means. The cooling system takes care of this additional heat. The cooling system is built into the engine. There are hollow spaces around each engine cylinder and combustion chamber. These hollow spaces are called waterjackets, since they are filled with water. When the engine is running, the water takes heat from the engine, becoming hot in the process. A water pump pumps the hot water from the engine water jackets into the radiator. The radiator has two sets of passages. One set carries air（ pulled through by car motion and the engine fan） . As the hot water passes through, it gives up its heat to the air passing 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 temperatures are prevented. Two general types of cooling systems are used, air cooling and 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 are cast into the cylinder blocks and heats. The engine fan is usually mounted on the water-pump shaft and is driven by the same belt that drives the pump  shaft 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 air so that heat will transfer from the water to the air. The radiator core is divided into two separate compartments; water passes through one, and air passes through the other. 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 surge 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 cause the engine ton operate. The ignition system consists three basic parts: the ignition distributor, the ignition coil, and the spark plug, together with the connecting wires. When the engine is running, the ignition coil is repeatedly connected, it becomes loaded with electrical energy. Then, when it is disconnected, the “load” of electrical energy is released in a high-voltage. 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 less than one three-hundredth of a second. That is, there will be as many as 300 of these events every second that the engine is running at high speed. Some systems use transistors to reduce the load on the distributor contract points. Other systems do not have contract points use instead a combination of transistors and a magnetic pick-up in the distributor.  The ignition distributor has two jobs. First, it closes and opens the circuit between the battery and the ignition coil. The distributors 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. 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. 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. In the case of automobile engines, the mixture in the cylinder, after being compressed, 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 and exhaust valves of four-circle engines will permit a substantial part of the fuel-air mixture to escape during the compression stroke. Also, the heat loss from the compressed air to the cylinder walls will be greater at low speed because of the longer exposure. The escape of air and the loss of heat both result in a lower temperature at the end of compression. 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 engine. The starting system contains a cranking, or starting, motor and other accessories.  The starting motor electrically cranks the engine for starting. It is a special 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 assembled around pole shoes; the drive housing, which house the drive assembly and supports the motor on the engine flywheel housing; the armature; and the drive assembly. Some cranking motors also have a solenoid that operates the shift lever. 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 depressed. The present system that has been almost universally adopted for passenger cars and many other vehicles has starting contacts in the ignition switch. When the ignition key is turned against spring pressure 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 pressure 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 its stopped for fifteen seconds. The manual transmission shown in Fig. 1 provides a means of varying the relationship between the speed of the engine and the speed of the wheels .Varying these gear ratios allows the right amount of engine power at many different speeds. Manual transmission requires use of a clutch to apply and remove the torque to the transmission input shaft. The clutch allows this to happen gradually a so  that the car can be started from a complete stop. Modern manual  transmissions do not disengage any of the forward drive gears, they are simply connected to their shafts through the use of “ synchronizers” .Reverse is achieved reverse idler gears ,which are engaged to move the car  backwards. Some manual transmissions have an “ overdrive” . An overdrive is a mechanical unit bolted to rear of the transmission. It is usually known as the  fifth gear .When you use it, it will reduce the engine speed by about one-third ,which maintaining the same road  speed. In an automatic transmission, gear  ratios are changed automatically.  This eliminates the  need for the driver to operate the clutch and manually “ shift gears.”  The typical automatic transmission combines a fluid torque converter ,  a planetary-gear system, and a hydraulic control system in a single unit. As car speed changes , various gear ratios between the crankshaft and the wheels are  selected and then changed automatically. Automatic controls inside the transmission supply the proper ratio for the driving condition. In addition  to  the forward-gear ratios, neutral, and reverse, the automatic transmission has a PAPK position. This locks the transmission to prevent the car from moving or  rolling away while parked. 差速器和车桥  差速器和后桥壳总成的一个部件，后桥壳总成包括差速器、后桥、车轮和轴承。  如果汽车按直线行驶，就不需要差速器了。然而，当汽车转弯时，外测的车轮一定比内测的车轮行驶更长的距离。差速器可在汽车转弯时使两个后车轮以不同的转速转动，同时还向两个后轮提供动力。  后桥与车轮相连，内端装 有一个半轴齿轮。差速器壳支承在左侧车桥上，而且能够在轴承上做独立转动。差速器壳支承在行星齿轮轴上，行星齿轮与两个半轴齿轮相啮合。冠状齿轮与差速器壳相连，这样当冠状齿轮由传动齿轮驱动转动时，差速器壳也在转动。  也就是说，驱动力是从传动轴末端的传动齿轮输送到差速器的。传动齿轮与一个很大的冠状齿轮啮合，传动齿轮驱动冠状齿轮。  冠状齿轮与差速器齿轮轴相连，差速器齿轮轴上装有两个行星齿轮。每个后车轮都有一个独立的车桥，两个半轴齿轮用花键与两个车轴的内端相连。两个行星齿轮与这两个齿轮相啮合。当汽车直驶时，两个行星齿轮不 在齿轮轴上转动，但却向两个半轴齿轮传递动力，这样半轴齿轮与冠状齿轮的转速相等，从而使两个后轮也以同样的速度转动。  当汽车转弯时，外测车轮就必须比内侧车轮转的更快。为了达到这一目的，两个行星齿轮在齿轮轴上转动，给外侧的车轮提供比内侧的车轮更多的运动，这样外侧车轮轴上的半轴齿轮比内侧车轮轴上的半轴齿轮转动更快，这样，当汽车转弯时，外侧车轮就转的更快些。  车桥有两种基本形式：非断开式和断开式。非断开式车桥不转动，而车轮在车桥上转动。最常见的例子就是在马车上所见到的非断开式车桥，断开式车桥与车轮相连，这样两者一起转 动。断开式车桥根据其承载可分为：半浮动，四分之三浮动和全浮动。               汽 车 系 统  发动机的燃油系统：  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和气（具有较高的燃油比例）。这是因为在低温下燃油不能迅速汽化，因此，要在混合气中额外增加燃油，这样才有足够汽化燃料形成可燃混合气。  燃料系包括汽油箱、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，燃油喷射泵取代了化油器。  汽油箱用来储存汽油，通常安装在汽车的后部。油箱由金属板制成，固定在车架上。  油泵把油箱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。燃油系统装有滤清器和过滤网，防止燃油的杂物进入燃油泵和化油器。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。  化油器实际上是一个把液体燃油与空气相混合的混合气形成装置。在这一过程中，化油器把燃油以雾状喷入流经化油器得空气中，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和通道，通过这些供油系统，再不同的行驶状态下，可提供不同的可燃混合气。  发动机冷却系统：  冷却系统的作用是控制发动机在各种转速和各种行驶状态下都能有效的控制温度。  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排除。是，残留在发动机中的余热仍足 以使发动机受到严重损坏，除非用其他方法排除这些余热，冷却系统就是专门消除这些余热的。  冷却系统就设置在发动机中。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。在发动机的运行过程中带走。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