Research On The Performance Of BEV Transmission Parking Mechanism

In recent years,the development of electric vehicles has been developing rapidly.Behind the continuous improvement of the power and economy,the safety of electric vehicles is also getting more and more attention.As one of the main systems of automatic transmission,parking system is also an important safety device.It has been widely applied to electric vehicle transmission,and gradually developes from traditional mechanical cable structure to electric control.Based on a 2-speed and electronically controlled automatic transmission that developed for an independent brand vehicle,this paper analyzes and studies the electric parking system of its main systems.First,the structure schemes of several typical parking mechanisms are analyzed and compared,and the advantages of the electronic control system are pointed out.According to the functional requirements of parking mechanism,the theoretical calculation and research on the key structure design are done,and a series of representative performance parameters are obtained,and the parameters conform to the requirements of the relevant specifications.Then,in view of the irregular shape of the parking mechanism,and the existence of nonlinear elastic elements,various forms of motion contact and the loss of collision energy,a multi-body dynamic model is established by ADAMS,and various typical working conditions are analyzed in detail.The simulation results are consistent with the theoretical calculation.Secondly,aiming at the strength analysis of parking mechanism,considering the maximum locking force which can be achieved in actual use,a further analysis is made to determine the torque loading value.Using HyperMesh and ABAQUS to establish the finite element model,the dynamic contact stress of the bearing parts is analyzed,and the strength performance of the parking mechanism is confirmed.Thirdly,based on the electronic control structure scheme,the calculation and selection of the motor and ball screw are completed.The control logic of the parking drive system is analyzed,and a brief control logic model is established by using Stateflow.Finally,a test bench of the parking mechanism is built,and a mechanical flywheel is designed to simulate the inertia of the vehicle.The bench test is completed and the test results are analyzed and evaluated,and the actual performance parameters of the parking mechanism are confirmed.The wear problems and solutions of parking mechanism are analyzed and introduced.