| With the rapid development of new energy bus industry,pure electric bus has been widely concerned by bus manufacturers.The reducer used in electric bus is directly driven by motor,which makes the structure of the drive system more compact.Compared with the traditional bus,the engine and exhaust system,which contribute the most to the noise,are cancelled.However,due to the high input speed of the motor,the gear transmission system of the reducer produces a strong noise in the process of high-speed meshing.Therefore,reducing the noise of the electric bus reducer has gradually become the focus of attention of researchers.The research object of this paper is the planetary gear train transmission system for new energy bus,and its dynamic response and optimization were studied.The dynamics model of the planetary gear system was established by using the lumped parameter method,and the dynamics equations were solved by using the dynamics theory to analyze the magnitude of the excitation force.At the same time,the transmission simulation model was established,and the simulation and test results before and after optimization were compared respectively,which verified the feasibility of the optimization method.The research results have certain theoretical significance and engineering value for the dynamic response analysis and optimization of planetary gear transmission system of new energy reducer.The main research contents of this paper are as follows:1.The dynamic vibration response of the system caused by gear meshing transfer error and dynamic meshing stiffness was studied.Firstly,the dynamic substep simulation analysis of the gear meshing process was carried out by slicing algorithm,and the factors causing the transfer error were transformed on each contact slice,and then the transfer error was obtained by numerical analysis and calculation.Based on the lumped parameter method to extract the shafting bending-torsion-shaft-place of stiffness/mass matrix,through force analysis of exterior and interior meshing gear pair is established additional coupling stiffness matrix,at the same time,the establishment of a bearing nonlinear stiffness matrix,using the theory of mechanical vibration calculation of gear system dynamic flexibility matrix,and then can get dynamic meshing stiffness of gears.The dynamic meshing force was calculated by the meshing transfer error and the quadratization of the dynamic meshing stiffness,and the vibration response of the gear transmission system was calculated by combining the dynamic flexibility of the established gear transmission system.2.Taking planetary row reducer for new energy bus as the specific research object,a transmission simulation model is established according to CAD drawings.The reliability of the modification scheme can be determined by comparing the contact stress of tooth surface before and after modification.The transmission error and dynamic response of this planetary gear reducer were simulated,and a test rig was built to carry out dynamic response test.The simulation and test showed that the dynamic response numerical value needed to be further optimized to improve the NVH performance.3.By studying the influence of gear design parameters on vibration,the macro parameter design schemes of two groups of gears were determined,and the modification parameters were determined according to the tooth profile modification and tooth direction modification principles.The transfer error and tooth surface contact stress simulation of these two groups of parameters were carried out,and the optimization scheme was determined according to the actual situation and other factors.The dynamic response of the optimized gear parameters was simulated and tested,and the test results showed that the dynamic response of the reducer was generally reduced by about 10%,which indicated the reliability of the optimization scheme. |
