The Root Cause Analysis And Improvement Of The Gear Whine Of The Manual Transmission For Car

Gear whine is medium to high frequency pure tonal noise which is a common problem in the useof the automotive transmission. And although its Sound Pressure Level (SPL) is low, it is also easy tobe feel subjectively by human ears, which affects vehicle ride comfort. How to avoid and control thegear whine is currently a hot point in the research of transmission noise.In this paper the cause of the gear whine is analyzed. Then the gear whine can be reduced byreducing the incentive and redesigning the structure of the transmission system.The model of the transmission box is established; then, the natural frequencies and mode shapesof the transmission system are analyzed, followed by experimental model verification of the accuracyof the established model. On the basis of the modal analysis result, the gear meshing frequencies andthe frequencies of rotation of each axis and also the amount of engine main harmonic excitationfrequencies are calculated, and then the excitation frequencies are compared with the naturalfrequencies of the transmission system to find the resonant frequencies, which provides the referencefor the gear whine optimization design. By analyzing the dynamic response of the transmission drivesystem which is excited by the transmission error, the relationship of the transmission error and thegear micro-geometries parameters is discussed, and the transmission error excitation can be reducedby reasonable choice of the gear micro-geometries parameters; then the dynamic response at eachbearing are calculated, such as response force, displacement, velocity. In order to avoid the naturalfrequencies of the transmission system with the excitation frequencies, the effect of the geartransmission system’s parameters including the normal module, helix angle, number of teeth on thesystem’s natural frequencies is studied. By choosing parameters optimally, the excitation frequenciesare away from the natural frequencies of the system, gear whine is reduced successfully.The research methods and results of the paper can provide some engineering applications valuefor reducing gear whine.