Study On Drive And Running Performance Of Large Wheel Loader Based On Limited-Slip Differential Systems

As a type of earth moving machinery, Wheel loaders are mainly operated on roughterrain with complex work environment. They are often encountered on the terrain withdifferent adhesion conditions between tires. The differences of the road-tire adhesioncoefficients will produce different levels of tire sliding. Excessive sliding of the tires canlower the drive performance, transmission efficiency, passing ability and fuel economy. Inaddition, the slip rate of the tires is one of main factors affecting the critical wear life ofwheel loader tires.At present, limited-slip differential is usually assembled in drive axle of modernwheel loaders to solve the above problems, most in front drive axle, others in both frontand rear drive axles. The series of problems caused by excessive tire sliding can beimproved at some level by the application of drive axle with limited-slip differential.Therefore, the main purpose of this paper is analyzing the impact on drive performance,transmission efficiency, passing ability and fuel economy of loaders produced by the aboveimprovements, based on the study of the working principle and characteristics oflimited-slip differential.The previously mentioned problems have been improved by the application oflimited-slip differential to a great extent, but limitations still exist. For example, in thesteering process, the limited-slip differential can not be unlocked which will affect theloader’s steering ability, reduce the transmission efficiency and decrease tire wear. Inaddition, the locking coefficient can not be adjusted, which will also affect its adaptabilityto different working conditions and transmission efficiency. So, another part of the purposeof this article is to explore utility of the electronically controlled differential on wheelloaders in the basis of previous studies. In this paper, the following work is completed:1. The derivation of the limited-slip differential mathematical model and establishmentof the simulation model is completed by the study of Structural characteristics and workingprinciples. mathematical model and simulation model of active differential are alsoobtained at dynamics and kinematics point of view.2. Mathematical model of8-DOF vehicle dynamics, powertrain system and tire dynamics are deduced based on80type wheel loader. And the simulation model is built inMATLAB/SIMULINK environment.3. The control strategy of active differential is designed separately based on thedriving and steering process. According to the actual situation, four types of driveaxles(type1:with active differentials in both front and rear drive axles; type2:withlimited-slip differentials in both front and rear drive axles; type3:with open differentials inboth front and rear drive axles; type4:with limited-slip differential in front drive axle, withopen differential in rear drive axle;) configuration are designed. in several typical workingconditions, the impact of the four types of drive axle on loaders has been analyzed.The main conclusions are:1. In extreme road conditions, loader with type1and type2drive axles can ensure itspassing ability, in consideration of adaptability to the extreme road conditions, former issuperior to the latter, mainly in the vehicle speed and traction efficiency. Under normalroad conditions, loader with type1, type2and type3drive axles can guarantee the driveperformance. The locking coefficient of limited-slip differential is un-adjustable, whichaffects its adaptability to different working conditions and transmission efficiency.2. In steering process, loader with type1axle can turning with a smaller radius, whichis beneficial to working efficiency. By contrast with type2and type3, loader with type1axle can enhance the tire wear, and improve the steering portability.3. In V type operation cycle condition, by contrast with type3, loader with type1,type2and type3reduce the time6.2%,3.4%and2.7%, respectively. And the fuelconsumption is reduced by7.5%,4.7%and3.5%, respectively. Depth of Shoveling isincreased by13.9%,7.8%and3.5%, respectively. Loader with both type1and type2driveaxles could lower the amount of sliding, the former is advantageous in reducing the tireattrition.