Research On The NVH Problems Of A Commercial Vehicle’s Rear Axle Transmission

Automotive NVH technology is an important indicator of the level of the automotive industry.Domestic studies about the impact of transmission system on the Vehicle NVH characteristics stay in the stage of ‘trial and error’.In recent years,the complains about the noise of the vehicle’s rear driving axle system is more and more in the market,which greatly limit Chinese automobile independent brands’ development.Predicting and optimizing the impact of transmission system on the Vehicle NVH characteristics by CAE in development phase,can reduce development risks and shorten product development cycles.This paper firstly introduces the rear axle transmission system’s NVH research status at home and abroad,as well as the basic principle of rear axle transmission system vibration noise.Second,this paper theorizes following main factors that are affecting the shaft vibration: the determination of shaft residual unbalance,the assembly process of the drive shaft,the arrangement of the drive shaft,the critical speed of drive shaft,the vibration isolation of the shaft support position in the middle,the first-order bending mode of drive shaft,and so on.If these problems are solved in the vehicle development phase,the risk of transmission shaft vibration can be minimized.Then it illustrates the loading condition of analyzing the rear axle drive system strength stiffness and how to use software Hypermesh and Abaqus to analysis the strength and stiffness of main retarder.According to the analysis results,main reducer system can be optimized until achieve the desired effect.And the structure causing strong vibration problem is solved.Furthermore,the CAE principles and method of modal analysis on rear axle transmission system are studied.At the beginning,the main reason of causing rear drive system’s vibration noise is analyzed.Next the modal is computed by CAE.At last,some parts are improved to meet modal design requirements.Finally a model whose contains the correct gear parameters of the rear axle drive system is built by Masta software.In this section,the dynamic response of rear axle drive system is analyzed,which is helping judge whether the improvements of rear axle drive system can meet NVH requirements.