Parameter Matching Design And Optimization Of Two-speed Automatic Transmission For Electric Vehicle

As environment problems such as energy crisis, air pollution and global warming become increasingly serious, the automotive industry is facing more stringent requirements for energy conservation and emission reduction. Pure electric vehicle has received worldwide attention because of its many advantages, such as high efficiency, energy saving, zero-emission. It is of great theoretical significance to make a research on parameter matching of pure electric vehicles powertrain and shifting actuator and optimizing shifting time, thus to improve pure electric vehicles technology and performance levels. Therefore, the speed ratio matching and the design of the structure of AMT for PEV was proposed, the parameter of shifting actuator for two-speed AMT was designed, and shifting time of AMT for PEV was optimized. The main works in this paper are as follows:(1) Parameters matching of power transmission system of PEV: According to the economy and power demand of automobile, parameters of powertrain including driving motor, transmission box, battery were matched, the power and speed of the drive motor, transmission gear and speed ratio, battery type and capacity were determined, based on considering battery weight on vehicle performance.(2) Parameter matching of the transmission gear box for PEV: With the minimum volume of the gear box and the maximum of the gear transmission coincidence degree, the matching optimization is carried out, the arrangement type of the gear box, the number of gear teeth, modulus, tooth width of the two- speed transmission gear box were determined, to meet the demand of make the transmission structure more compact and lower cost.(3) Parameter matching of shift actuator for two- speed transmission: First,the force of the synchronizer is analyzed, and the maximum synchronization force is obtained, the shifting fork pin is analyzed to obtain the dynamic model of the gear shifting mechanism, with the minimum time of engaging to1 and power of shift motor as the optimizational target, parameters of shifting actuator including shifting motor, worm gear, camshaft were matched, shifting motor power, the worm gear transmission ratio and the angle of groove of the camshaft in engaging to 1 are determined; then, according to the matched parameters, based on camshaft groove making up-shift and down-shift with different planes, the optimal angles of the engaging and disengaging gear groove were determined repectively.(4) The shift time optimization of the two-speed transmission for PEV: Shift control process was analyzed, the time for each shift step is determined by the hardware of the transmission and the speed difference of synchronization and so on. The drive motor speed control model and the synchronization model are set up respectively, with the minimum time of speed controling of driving motor and synchronization of synchronizer, best synchronization speed differences in the up-shifting and down-shifting were determined respectively, providing the theoretical support for the target value of the motor speed regulation during the gear shifting process.