Simulation Analysis Of Gear Vibration Noise And Optimization Design Of Pure Electric Vehicle Two-Speed Gearbox

Due to the scarcity of resources per capita and the increasingly serious environmental problems,environmentally friendly,clean and efficient pure electric vehicles emerged as the times require.Pure electric vehicle matching gearbox can improve the performance of the whole vehicle,and has many advantages compared with single-stage deceleration.However,there are relatively few studies on the performance of pure electric vehicle gearbox at present,especially the standard for noise characteristics of pure electric vehicle gearbox is not yet perfect.Compared with the traditional gearbox,the increase of the speed and the change of the working environment make the noise problem of the pure electric vehicle gearbox more severe.Therefore,reducing the vibration noise of the pure electric vehicle gearbox has become an urgent task.This paper takes a new type of uninterrupted two-speed gearbox applied to pure electric mini-cars as the research object,to reduce the gear vibration noise of the two-speed gearbox.The vibration and noise characteristics of the gearbox are studied through the simulation analysis of the transmission system,combined with the theoretical methods of finite element and boundary element.Through the optimized design of the transmission system,the radiation noise of the gearbox is successfully reduced,which provides an effective method for improving the sound quality of the gearbox,and provides a research idea for solving such gearbox noise problems.The specific analysis process of this paper is as follows:1.The Romax simulation model of the two-speed gearbox transmission system of pure electric vehicle was established,and the reliability of the main components of the transmission system was verified by analysis and calculation.According to the cause of the gear whine,the transmission error of the gear under different working conditions and the vibration response of the gear and bearing under the excitation error are obtained.The results show that both the transmission error of the gear and the dynamic response of the bearing are in urgent need of improvement.2.According to the modal analysis theory,the natural frequency and natural vibration mode of the gearbox housing are solved in Ansys Workbench.The dynamic response of the bearing obtained by dynamics simulation is used as the load condition,and the harmonic response analysis of the gearbox housing is carried out by modal superposition method.And the vibration response of the gearbox is calculated under the highest speed conditions of the two speed.Based on the gearbox displacement of the harmonic response analysis,the boundary element mesh model of the gearbox housing is created in LMS Virtual.Lab Acoustics,and the acoustic radiation simulation is carried out.The sound pressure radiation cloud map at the field around the gearbox and the sound pressure frequency function at different locations are obtained.3.Aiming at the problem of large radiation noise of the gearbox,a solution to optimize the design of the gear is proposed.The three sets of gears are redesigned from two aspects: macro parameter optimization and micro modification.Considering the constraints of processing technology and space size,the gear contact ratio should be improved as much as possible,and the gear profile and lead should be optimized to reduce the transmission error and increase the stability of the gear transmission.The simulation and experiment results show that the radiated noise of the optimized gearbox is obviously reduced,the average reduction of the first speed case is 3-4 dB,and the average reduction of the second speed case is 4-5 dB.The vibration and noise problem of the two-speed gearbox of pure electric vehicles has been effectively solved.