Modeling And Research On Performance Optimization Of Multistage Main Pressure Regulating Value For AT

Hydraulic automatic transmission is widely used in heavy engineering vehicles because it can make engineering vehicles get good starting acceleration performance and improve the ability of vehicles to adapt to complex roads.The shift operation,shift control and lubrication of hydraulic automatic transmission depend on hydraulic control system.The main pressure regulating valve plays an important role in the hydraulic control system of the hydraulic automatic transmission.The general hydraulic control system relies on the main pressure regulating valve to output constant main oil pressure to supply oil to the shift clutch,while the demand of the shift control system for working pressure varies greatly under different working conditions.At present,the existing main pressure regulating valve in China is generally replaced by relief valve,which can only adjust the single-stage pressure.The pressure regulating accuracy is poor in a large flow range,which limits the improvement of the performance of hydraulic automatic transmission.Aiming at the main pressure regulating system in the hydraulic control system of high power hydraulic automatic transmission,this paper designs a multi-stage main pressure regulating valve with high precision,high speed and high stability.Firstly,combined with the working requirements of the main pressure regulating valve in the main pressure regulating system of the automatic hydraulic transmission,the structural scheme of the multi-stage main pressure regulating valve with multiple feedback cavities is determined,and the design and calculation of the overall structure of the multi-stage main pressure regulating valve are completed.In order to improve the constant pressure accuracy of the multi-stage main pressure regulating valve,a shoulder structure is set on the valve core at the overflow return tank port of the multi-stage main pressure regulating valve for steady-state hydrodynamic compensation,and the flow field simulation software CFX is used to simulate and analyze the structure,which provides the basis for the design calculation and static and dynamic simulation of the multistage main pressure regulating valve.Secondly,based on the structural design of multi-stage main pressure regulating valve,the static and dynamic mathematical model of multi-stage main pressure regulating valve is established.The static simulation model of multistage main pressure regulating valve is obtained by compiling m file in MATLAB.The nonlinear dynamic simulation model of multi-stage main pressure regulating valve is built in Simulink,and the static and dynamic simulation of multi-stage main pressure regulating valve is realized.The influence of the key structural parameters of the main pressure regulating valve on the static and dynamic characteristics of the multi-stage main pressure regulating valve is analyzed,which lays a foundation for the optimization of the dynamic performance of the multi-stage main pressure regulating valve.The simulation analysis of the influence of different set pressure switching and shifting oil changes on the dynamic characteristics of the multi-stage main pressure regulating valve is completed.Thirdly,according to the simulation results of static and dynamic characteristics of the multi-stage main pressure regulating valve,the key structural parameters affecting the dynamic characteristics of the valve are determined,and the optimization mathematical model based on ISE error integral criterion is established.The m file is compiled to make the data exchange between the Simulink nonlinear simulation model and the MATLAB optimization toolbox.The dynamic characteristics of the multi-stage main pressure regulating valve are optimized with the help of the genetic algorithm provided by the optimization toolbox,and then the results before and after optimization are compared and analyzed.Finally,the steady-state hydrodynamic test bench of multi-stage main pressure regulating valve is designed,which provides a solution for the subsequent verification of the compensation effect of shoulder structure on steady-state hydrodynamic.the performance test bench of multi-stage main pressure regulating valve is built to verify the static characteristics of multi-stage main pressure regulating valve and the switching of different set pressures.The results show that the static characteristics of multi-stage main pressure regulating valve are consistent with the simulation,and it is feasible to change the set pressure at the valve inlet by connecting different feedback cavities.