Research On Vibration And Noise Reduction Of Electric Vehicle Transmission Based On Gear Modification

With the increasingly severe environmental protection situation and the exhaustion of traditional energy,pure electric vehicles have been widely used because of their low energy consumption and low pollution.Due to the difference of background noise,operation condition and installation arrangement between the pure electric vehicle transmission and the traditional vehicle,the research on the improvement of its vibration and noise is particularly important.In this paper,the two speed automatic transmission of a pure electric vehicle is taken as the research object.The generation mechanism and transmission path of transmission vibration and noise is studied,and the excitation source of transmission gear transmission system is analyzed emphatically: the time varying meshing stiffness excitation of gears,the error excitation of gears,the entry and exit meshing excitation of gears.Based on the analysis of the excitation source,the concept of transmission error of gear pair,which is closely related to the dynamic response of gear transmission system,is introduced and the relevant calculation and analysis are carried out.The vibration system model of transmission gear pair is built and the non-linear dynamic equation of transmission gear transmission system is analysis,furthermore,the numerical simulation of displacement excitation is carried out.The rigid-flexible coupling simulation model of multi-body dynamics of transmission is established,and the static analysis and dynamic response analysis are carried out.The theory of gear modification is studied and the influence of profile crowning in tooth direction,slope modification in tooth direction,tooth profile crowning and tooth profile pressure angle on transmission error and tooth surface load is analyzed.Based on the orthogonal optimization method,the gear modification scheme with small transmission error and better load distribution on the gear surface under different working conditions is obtained.According to the designed modification scheme,the trial production and optimization of the gears and the assembly of the transmission are carried out,and the accuracy of the simulation model construction of transmission and the uniform distribution of load on gear surface after modification are verified by the gear contact pattern test.Through the comparison of transmission error of gear pair,load distribution of gear surface,vibration response of bearing nodes on the surface of transmission case and radiation noise of transmission before and after gear modification,the important role of gear modification scheme in the study of vibration reduction and noise reduction of transmission is explored.The research method of transmission vibration reduction and noise reduction based on gear modification in this paper has certain guiding significance for the research of NVH performance of electric vehicle transmission.