Dynamic Characteristics Research Of Reducer Housing For Electric Vehicle

With the fast development of new-energy vehicle industry,electric vehicles have received unprecedented attention.Due to the difference in the powertrain of the pure electric vehicle and the traditional fuel vehicle,there are significant differences in the source of excitation for automotive vibration.In terms of pure electric vehicles,the main factors that produce vibration noise are motor and reducer.Since the vibration of drive motor is weak,the vibration of reducer is particularly significant which greatly affected the comfort performance of passengers.So the dynamic response analysis of the electric vehicle reducer has great engineering significance and application value.This article is based on the promotion project of new energy vehicles reducer NVH performance,and focuses on the dynamic response of the reducer by using the method of multi-body dynamics and finite element simulation analysis on maximum torque speed condition.The main contents are as follows:(1)Simulation of bearing excitation force.Establish the rigid body dynamic model of gear transmission system by the ADAMS,and then replace the original rigid body with flexible body of the gear transmission system.Establish a flexible body dynamics model to derive the dynamic load excitation at each bearing.The results showed that the dynamic excitation at the bearing was periodic.(2)Finite element analysis of gearbox housing and dynamic stiffness analysis of mounting points.Import the entity model of transmission box into the HyperMesh to establish the correct and reasonable finite element model.Modal analysis are conducted and prepare for dynamic response analysis.The dynamic stiffness of the suspension connection point is analyzed and the results show that the minimum dynamic stiffness of each connection point in each direction is greater than the industry target of10~4 N/mm.(3)Modal test of the gearbox housing.The modal test of the gearbox housing is conducted by the method of moving hammer.The experimental results show that the results of the calculated modal analysis in the range of 0~3000Hz are in agreement with the 8 steps of the experimental modal analysis and the maximum calculation error is 2.1%,which shows that the finite element model of the transmission housing established in HyperMesh is correct.(4)Dynamic response analysis of the gearbox housing.The modal superposition method is used to calculate the harmonic analysis of the transmission box,and get the displacement response of each bearing hole and the stress distribution of the box.The results show that the vibration displacement of the bearing hole of the left box output shaft and the intermediate shaft are larger than others and need to be optimized.(5)Gearbox housing optimization design analysis.Widen or heighten the ribs near the bearing box hole of the left box intermediate shaft and output shaft,and the constraint modal and harmonic response analysis is conducted again.The results show that most of the constraint modes are improved,and the vibration displacements of the left-hand box intermediate shaft and the output shaft bearing hole are reduced,which proves that the optimized design is reasonable and effective.