Analysis And Optimization Of AT Electro-hydraulic Control System

Based on the transmission scheme and structural characteristics of a certain autonomous 8-speed AT,the principle and dynamic response characteristics of electro-hydraulic control system are analyzed in this paper.Some parameters are optimized and results are compared with which are under the initial parameters.Making the best use of Industry-Academy-Research cooperation provides the basis for further improvement of the performance of the electro-hydraulic module of AT and forward design and development.The concrete contents are as follows:(1)The structure and working principle of 8AT is introduced.The transmission line of the power flow route is analyzed.The relationship of torque among parts and the change of speed of revolution and torque are analyzed by lever method on power upshift and power downshift respectively.That way the change process of the rotational speed and torque of the friction element in the process of bonding and separating of the coupling element is obtained.(2)The schematic diagram of the electro-hydraulic control system is plotted.The whole electro-hydraulic system is decomposed into three subsystems,such as oil pressure regulating and flow control system,shift control system and torque converter oil locking control and cooling lubrication system according to different functions.Combined with the structure schematic diagram and the hydraulic symbol schematic diagram of each component,the working principle of each subsystem is analyzed.(3)The mathematic model of the proportional electromagnet valve is established.Based on ANSYS Maxwell software,the proportional electromagnet is simulated.The change of parameters,including magnetic lines of flux,magnetic force,current,induction voltage,inductance,magnetic chain,velocity and displacement of valve core,are analyzed.Parametric analysis of the proportional electromagnet is made.As a result,the influence of mass of the armature,coil turns and parameters of the pot-typed yoke on electromagnetic force is obtained.Some parameters of proportional solenoid valve(the mass of spool,the stiffness of spring,preload of spring,diameter of inlet throttle)are optimized,which improves the rapid response of the proportional solenoid valve.(4)The mathematic models of shift valve and clutch are established.Dynamic characteristics are simulated by the AMESim software.The influence of different parameters on the dynamic response of pressure is analyzed.According to the result of parametric analysis,the correlative parameters of the shift valve-clutch pressure control system are optimized with the established target function based on the ITAE criterion,which makes comprehensive performance of the system improved.The simulation model of shift control system is established.The curves of the output pressure of proportional solenoid valve and shift valve,pressure of the clutch,displacement of the piston and rotational speed of the active and driven part of the clutch are calculated by using the optimized parameters.