Study On The Shifting Characteristics Of A Two-speed Planetary Transmission Based On Tooth Brake

In this paper,the object is a two-speed planetary gearbox based on tooth brake applied to electric vehicle.Compared with the traditional gearbox,it has some advantages such as the small occupied space,strong environmental adaptability,high transmission efficiency.It takes full use of the function of speed regulating of the motor during shifting,the speed of the gear ring is adjusted to an appropriate small value,and the main and the passive end of the toothed belt brake are joined to complete the braking and achieve the shift.In order to study the dynamic characteristics and its influencing factors during the condition of shifting transition of the gerabox,the dynamic simulation of joint characteristics of the tooth brake and the shifting characteristics of the gearbox and relative experimental research were carried out.(1)The finite element simulation model of electromagnetic linear actuator was established,and the electromagnetic force characteristics of different coil positions and different current sizes were simulated and analyzed.On this basis,the mathematic model of the joint process of the tooth brake was established.And the joint process was simulated by Matlab simulation software.The range of the braking drum angular velocity making the brake joint successfully and its dynamic characteristic curve were obtained.In addition,the main influencing factors and their influence laws were determined.(2)The dynamic model of the planetary gearbox was established by using the virtual displacement principle,the dynamic shifting processes comparison and simulation analysis between the planetary transmission using tooth brake and friction brake done.The simulation results show that the shifting time of the planetary transmission using tooth brake was lower than using friction brake in the same maximum torque impact.And the time required for its upshift process was significantly higher than that of the downshift process applied with the same joint speed.In order to obtain the influence laws of different influencing factors on the shift characteristics,the joint speed of the brake,the electromagnetic force,the torque control of motor,the torque moment and the shift speed on the gearshift characteristics were studied.(3)The test bench of the joint characteristics of the tooth brake was designed,and the feasibility of the braking function was verified.The correctness of the torque impact calculation method during simulation and the influence laws of different angular velocity on the torque shock were studied through the tests.