The Design And Development Of Two-speed Automatic Transmission Shift Actuator For Electric Vehicle

In this paper,the shift actuator of two gear automatic transmission belong to multi-mode electromechanical coupling system is designed and researched,shifting actuator is an important component to realize the shifting automation of automatic transmission as well as to switch between the different modes smoothly,so it has important effect on the accuracy and speed of the change operation.We design a shift actuator which meet the shifting performance requirement for two automatic gearbox based on the needs of the project.Firstly,we compare the merit and demerit between the different gear shifting actuator dynamic source types and motion transfer mechanisms via consulting lots of literature.Considering the practical requirements of the project,we determine the type of shifting actuator which include the following characteristics: electric controlling and engine driving,spatial cam,12 V DC motor.In addition,we design the parameter according to shifting demand,using weight function method to select the spatial cam spiral angle optimally.And using software ADAMS to conduct kinematics analysis on the shift actuator to verify the execution displacement is consistent with expected design or not.Secondly,we analyze the structure and shifting process of drive motor-two automatic gearbox coupled system based on multi-body dynamics theory,determine the degree of freedom of the system at different stages,using Lagrange equation to proceed the dynamics modeling for shifting process,solve the motion state of each degree of freedom at different stages via dynamic equation.In addition,we using the software matlab to model and simulate,research the quality of shifting process,the shifting force curve obtained through simulation provide the basis for the loading experiment of the shifting actuator.Finally,the experiment was carried out on the shift mechanism to verify that the designed shifting actuator meets the design requirements.The experiment is divided into two situations: no-load and load,no-load condition for functional experiment,mainly test whether execution displacement of shifting actuator is consistent with expected design,the existence of motion interference,etc,the experimental results show that the displacement conforms to the designed value.Under load case,we calculate the load torque response to the spatial CAM according to shifting force curve of two gear automatic transmission shift process simulation,load torque load through the magnetic powder brake,load cases mainly observe how long the actuator executes corresponding displacement under the action of a load,if there is a large shift displacement curve fluctuations,whether the motor meets the demand of shifting process,etc.Experimental results show that the actuator displacement can be executed within the allotted time corresponding,and the displacement curve is relatively stable,no big impact.