传动系 翻译.doc

Power TrainThe power train serves two functions: it transmits power from engine to the drive wheel, and it varies the amount of torque. The power train includes: engine: that produces power; transmission: either manual or automatic; clutch: used only on manual transmission, or torque converter: used only in automatic transmission; drive shaft: that transmits the power from transmission to differential; differential: that carries the power to the two wheel axels. Manual transmissionThe function of a manual transmission (shown in Fig.5-2), is to transfer engine power to the drive shaft and rear wheel. Gears inside the transmission change the cars drive-wheel speed and torque in relation to engine speed and torque. This keep the engines output matched as close as possible to varying road speeds and loads.Automatic transmission Both an automatic transmission and a manual transmission accomplish exactly the same thing, but they do it in totally different ways. The key difference between a manual and an automatic transmission is that the manual transmission locks and unlocks different sets of gears to the output shaft to achieve the various gear ratio, while in an automatic transmission, the same sets of gears produces all of the different gear ratio. The planetary gear-set is the device that makes this possible in an automatic transmission.ClutchDriving a car with a manual transmission, you depress the clutch, select a gear, and release the clutch while applying power to get the car to move. The clutch allows engine power to be applied gradually when a vehicle is starting out, and interrupts power to avoid gear crunching when shifting. Engaging the clutch allows power to transfer from engine to the transmission and drive wheels. Disengaging the clutch stops the power transfer and allows the engine to continue turning without force to drive wheel.Torque ConverterThe key to the modern automatic transmission is the torque converter. It takes the place of a clutch in a manual transmission to send the power from the engine to the transmission input shaft. The torque converter offers the advantage of multiplying the turning power provided by the engine. Drive shaftA drive shaft and universal joints (U-joints) connect the transmission to the rear drive axle on most rear-wheel-drive vehicles. Many four-wheel-drive vehicle also use drive shafts and universal joints, with one drive shaft between the transfer case and rear drive axle and a second drive shaft between the transfer case and the front drive axle. The drive shaft is sometimes called a propeller shaft.DifferentialOn FWD cars, the differential unit is normally part of the transaxle assembly. On RWD cars, it is part of the rear axle assembly. Located inside the differential case are the differential pinion shafts and gears and the differential side gears.传动系传动系有两大主要功能：它能够将由发动机输出的动力降速增矩，并传递至驱动轮上。传动系统的主要机构包括：发动机：产生驱动力，自动变速箱：有手动变速和自动变速，离合器：只用于手动变速箱上，液力变矩器：只用于自动变速箱，传动轴：将经过变速箱转化输出的动力传递至差速器，差速器：将动力分配至两驱动半轴。 手动变速箱手动变速箱的主要功能，是实现对发动机输出动力的转化并传递至传动轴与后轮。变速箱中的啮合齿轮组能够有效地降低由发动机直接输出的高转速动力，并增大有效输出扭矩。这样才能保证发动机的输出动力能够适用于不同的车速与路况要求。 自动变速箱自动变速箱与手动变速箱同样都能够准确地达成动力的转化效果，但两者确实以完全不同的方式来完成的。两类变速箱最主要的区别在于手动变速箱是通过松脱或锁止输出轴上的不同齿轮组以获得各个不同齿数比率；但是再自动变速箱中，同一对齿轮组便能够不同齿数比率的形成。在自动变速箱中通过行星齿轮组的分配便能够实现。 离合器在驾驶带手动变速箱的车辆时，当你踩下离合踏板，选择一个档位齿轮组，然后再松开离合器时动力便能够传递并驱动车辆前进。离合器能够实现当车辆在起步将发动机输出动力的逐渐传递，并能在换挡时能够暂时切断动力传递以防止变速箱内齿轮因转速差太大而造成打齿. 啮合离合器能够实现驱动力从发动机到变速箱与传动轴上的传递，松脱离合器则能够实现在发动机正常工作的情况下，切断输出至驱动力上的动力传递。液力变矩器现代自动变速箱的关键在于液力变矩器，它可以取代手动变速箱中离合器的作用来完成发动机与变速箱输入轴之间的动力传递。液力变矩器的优点在于能够增加发动机输出动力的有效传递。 传动轴在大多数后轮驱动的车辆中主要是靠传动轴和万向节(U型节)连结着变速箱与后轮驱动桥。 许多四轮驱动的汽车中同样也运用了传动轴与万向节，它是通过一根传动轴将变速箱的动力传递至后驱动桥，并且再采用第二根传动轴将动力传递到前驱动桥上的。传动轴有时候也称作驱动轴。 差速器在前轮驱动车辆上，差速器装置是变速驱动桥上常见的装配。在后轮驱动车辆上，它通常也是装配在后轮驱动桥上。差速器壳里的构造是由行星齿轮轴与行星齿轮以及差速器半轴齿轮组成的。A manual transaxle (shown in Fig.5-3), is a single unit composed of a manual transmission, differential, and drive axles. Most front-wheel-drive (FWD) cars are equipped with a transaxle. Such transaxles are also found on some front-engine or rear-wheel-drive (RWD), four-wheel drive (4WD) cars and on rear-engine and rear-wheel-drive cars.A manual transmission requires use of a clutch to apply and remove engine torque to the transmission input shaft. The clutch allows this to happen gradually so that the car can be started from a complete stop.Manual transmissions usually have four or five speeds, an