1.Design of Drive Axle for Medium-sized HouseholdCar 1. The Purpose and Significance of Design and Analysis of Current Situationat Home and Abroad：

Drive axle is animportant part of automobile. The configuration and design characteristics ofdrive axle are important factors influencing not just influence the reliabilityand durability of automobile [1]. At the same time, they also significantlyaffect the power，ride quality, maneuverability and operational stability. The driveaxle assembly contains many parts, such as main reducer, differential,transmission device for driving wheels, axle housing and various gears. It canbe seen that the design of automotive drive axle has to deal with a wide rangeof components and interactions. which, to get a practical design experience,necessitate the mastery of relevant engineering skills through extensive studyof the state-of-the-art and practice of drive axle design [ 3].

The purpose ofthis research is to design the drive axle of the medium-sized family car., To start with the design, firstly I will consult the relevantliterature and design drawings to acquire the relevant background and knowledge. That knowledge I will use to use for this design project with the helpof proper design and analysis software. Such design and analysis software orCAD/CAE (Computer-aided design/engineering) software being widely used inautomotive industry. Learning and mastering their use can prove very beneficialfor any future study or work I want to do.

China isvigorously developing the automobile industry, and the balance and operabilityof the automobile with rear wheel drive axle will be greatly improved. When arear-wheel-driven car accelerates, the traction force will not be emitted bythe front wheel, so when accelerating a turn, the driver will feel a greaterlateral grip and good operation performance. Low maintenance costs are also anadvantage of rear wheel drive, although the cost will vary considerablydepending on the structure and type of vehicle. If there is a transmissionobstacle, there is no need to repair the rear-wheel drive axle car, but for thefront-wheel drive car, this may be necessary, because the two components aresitting together. Therefore, rear wheel drive will inevitably make the ridemore comfortable, thus bringing considerable economic benefits. At present, inthe design and manufacture of domestic multi-axle heavy duty trucks, in orderto simplify the structure and the arrangement of transmission shafts, thethrough-drive axle is often used to form a series of products. The drive axleof the drive axle is in series, and the drive axle passes through the driveaxle close to the transmission or the actuator to another drive axle. In thisarrangement, the drive axle must pass through the drive axle, which is calledthe through drive axle. Domestic single-stage deceleration through-drive axleis usually composed of axle housing, wheel hub, brake, through-type mainreducer and so on. The existing through drive axle has better powerdistribution and transmission function in the double drive axle, but in orderto connect the through axle assembly with the inter-axle differential, thethrough main reducer of this structure needs to offset the inter-axledifferential with the active bevel helical gear through the active and passivecylindrical gears in the arrangement, so that the through axle assembly canpass through and transmit power to the rear axle. Therefore, there are someproblems, such as complex structure, high manufacturing cost, low transmissionefficiency, poor cooling and lubrication, large volume and heavy weight. Thedirect through single-stage deceleration drive axle, which has compactstructure, low manufacturing cost, high transmission efficiency, good coolingand lubrication, can improve the use economy of automobiles, while maintainingthe good passing performance of automobiles.

At present,domestic manufacturers of drive axles can be divided into four categories. Firstcategory of manufacturers cooperates with well-known international brandmanufacturers to make use of their advanced technologies while utilizing theadvantages of domestic resources. For example, in 1995 Liugong established ajoint venture with German Zeifu Company in Liuzhou. Second category ofmanufacturers, through the transfer of advanced foreign technology [5], relyingon the local environmental advantages of the national enterprises, which occupythe majority of the domestic market, such as the introduction of Italian Fiattechnology, relying on China to start equipment technology Co., Ltd. is atypical representative. Third, according to their own needs, some main enginemanufacturers make use of their own resources for self-production and self-use,which is also a development mode of domestic drive axles. For example, thedriving axles used in medium and small horsepower tractors produced by ChangfaGroup are typical production self-use type. Finally, Longgong, Xugong and otherconstruction machinery manufacturers also produce their own drive axles, butthis mode is only self-sufficient, it is difficult to meet the external marketdemand.