Dynamics Simulation And Vibration Characteristic Analysis Of Two-speed Transmission For Electric Vehicle

Through long-term development,the automobile industry is now undergoing a major transformation.Automobile manufacturers at home and abroad have joined in the development of new energy vehicles so as to alleviate the energy crisis.In the development process of new energy vehicles,electric vehicles have become an important research direction.In order to better exert the performance of electric vehicles,it is necessary to equip electric vehicles with two-speed transmissions.Therefore,this paper analyzes the two-speed transmission of the electric vehicle based on the parameter data provided by the enterprise.Firstly,the main structure of the electric vehicle and the research of two-speed transmission at home and abroad are introduced.After explaining the working principle of the transmission,the three-dimensional model of the main structure of the two-speed transmission is built based on the parameter data provided by the enterprise.Then the dynamics model of the transmission system is established using RecurDyn.According to the speed(2800rpm)under the rated power of the drive motor,the dynamics simulation of the two-speed transmission is carried out under different working conditions,and the correctness of the model is proved from the aspects of the speed and the dynamic meshing force of the gear.The stress of each shaft under the first gear stable working condition is analyzed,which offers the reference for the design and optimization for the two-speed transmission.When the driving speed reaches 2800 rpm and 6000 rpm,through the dynamics analysis of the model,the bearing forces in different directions of each bearing under the first gear condition are obtained.It is found that the meshing force of the first gear pair makes the bearing 3 bear a larger radial force,and the bearing force will fluctuate more at 6000 rpm.The rigid-flexible coupling model of the first-gear driving gear is established and the dynamics simulation analysis is carried out.It shows that the stress is mainly concentrated in the meshing area in the maximum stress nephogram of the gear.Through the predictive analysis of the fatigue life of the gear,it is considered that the gear meets the requirements of design and use.When the input speed is 2800 rpm,the fatigue life of the upper and the lower shift fork of the transmission under different working conditions are analyzed respectively.It is found that the lower shift fork does not meet the design service life,so it is improved by the fillet method.After re-analysis,the improved lower shift fork has met the design service life.After the dynamics simulation analysis of the transmission system is completed,the bearing clearance under different speed conditions is analyzed using Campbell.It is discovered that the vibration of bearing 3 is mainly affected by the input shaft,tapered roller and constant mesh gear in the first gear condition;the vibration of bearing 1 and bearing 4 is mainly affected by the input shaft speed in the second gear condition,and the vibration of bearing 1 is more intense in the low frequency section.Finally,the vibration situation of the transmission housing under different working conditions is analyzed by the ERP method,and it is found that the vibration of the input shaft housing end and the output shaft housing end is violent;after the modal analysis of the housing,it shows that the first two modes of the housing may resonate during the operation of the transmission.And then,the housing is improved according to the results of ERP analysis.Through the re-analysis,the founding is that the first mode frequency of the housing is higher than the maximum excitation frequency of the system,which reduces the possibility the resonance of the housing.At the same time,the ERP of the housing under different working conditions is reduced compared with the housing before improvement,which proves the effectiveness of the optimization for the housing.This paper,taking the two-speed transmission of the electric vehicle as the research object,conducts the dynamics simulation and the analysis of the shift fork,gear,shaft,bearing and housing of the transmission,which is of great significance and reference value for the research and development of the two-speed transmission.