Dynamic Characteristics Research Of A Two-speed Automatic Transmission Housing For Pure Electric Vehicle

Automotive transmission is an important core components in powertrain.When it works,it suffers complex loads,its dynamic response characteristics has extremely important influence on the operation of the vehicle.This paper mainly researched the dynamic response characteristics of a two-speed automatic transmission(2AMT).The main works and achievements are as follows:(1) In order to analyse the internal load excitation which causes the vibration of the gearbox housing systematically and comprehensively,this paper researched its vibration mechanism,including gear mesh time-varying stiffness, time-varying damping and time-varying error. To save computational cost,this paper only researched a pair of teeth meshing with each other and set up a finite element analysis(FEA) model.Adjust the contact position of the gear with rotating the large and small gear respectively with a spacing of 3°. Obtained the normal contact force in the surface of the tooth profile and the deformation of the tooth at different locations. And then calculated gear mesh time-varying stiffness and gear mesh time-varying damping, use sine function analog gear mesh time-varying error approximately.The internal load excitation of gearbox housing were obtained using the above results.(2) In order to take full account of the effect of flexible drive shaft, set up rigid and flexible coupling model through established drive shaft's modal neutral file(MNF). At the same time set up gear transmission equivalent model and applied internal load excitation to this model.After that,the dynamic response at each bearing were obtained.(3) Obtained the first thirty natural frequencies and vibration model of the gearbox housing using finite element analysis software ABAQUS. The results showed the mesh frequencies of the gear may be associated with the first order, the second-order natural frequency of the gearbox housing and it will cause the vibration of the gearbox housing.(4) A pure electric vehicle will produce torque ripple when working with the drive motor. Use the harmonic exciting torque to simulate this periodic torque variation approximately.Obtained the dynamic response of the gearbox housing in frequency domain through harmonic response analysis.The results showed the most stress distribute in the area of the bearing, suspension points and around the left and right wall of the main reducer and each node have a larger displacement in the frequency which was closed with the third-order, sixth-order, eighth-order natural frequency and the gearbox housing's strength and stiffness met the design requirements.(5) Obtained the dynamic response of the gearbox housing in time domain using transient dynamic analysis based on dynamic load excitation of bearings.The results showed that the weak part of the gearbox housing mainly concentrated in bearing position and the body'swall.By increasing the wall thickness and adding reinforcing ribs can improve this problem.