Influence of the Sleeve Teeth Shape Parameters on the Shifting Process of Automated Manual Transmission for Electric Vehicles

Electric vehicles equipped with automated manual transmission (AMT) provide the potential for improving the power and economic performance. However, due to the direct connection between the driving motor and the input shaft of the transmission, the higher moment of inertia at the input of AMT would lead to a poor shift quality. Based on the dynamic analysis of the engagement process of AMT without synchronizer, the dynamic model of the engagement process was established by using AMESim software. Through the analysis of the engagement process, it was concluded that the higher contact force and longer meshing duration under reverse contacting engagement condition is the main reason for the shift difficulty. In order to improve the shift quality, the influences of the sleeve teeth shape parameters of reverse contacting chamfer on the engagement process were analyzed and the simulation validation was performed. The simulation results showed that reducing the width and increasing the angle of the reverse contacting chamfer can effectively reduce the engagement duration and the contact force impulse, although the vehicle jerk was increased slightly, which did not exceed the most stringent criterion value of 10 m·s-3. Optimization of teeth shape parameters of reverse contacting chamfer can be considered to improve the shift quality of the electric vehicle equipped with an AMT.