| The paper took the hydraulic system of the dual-motor hybrid transmission as the research object.The dynamic characteristics of the clutch hydraulic system in the hybrid transmission were studied.In the gearbox,the clutch is engaged and the speed is changed with shifting.Clutch engagement control is achieved by hydraulic system.The dynamic response characteristics of the clutch actuators determine their operating conditions,affecting engine start-up and vehicle shift performance.According to the requirements of the hybrid gearbox for shift quality and system pressure,the hydraulic system was developed and the hydraulic system principle scheme was determined.It includes a cooling lubricating oil circuit and a clutch hydraulic control oil circuit,and its main function is to control the switching of the clutch to complete the driving mode.If the dynamic and static characteristics of the hydraulic control system do not meet the control requirements,it may cause large fluctuations in oil pressure when the clutch is engaged.It even causes the clutch engagement process to jitter phenomenon sharply,affecting transmission system performance and clutch life.To solve this problem,this paper aims to improve the control accuracy and stability of the clutch hydraulic system.And the dynamic characteristics of the clutch hydraulic system were analyzed and improved.Main tasks as follows:(1)The hydraulic valve block independently developed by the project team was the research object.The working principle was introduced in detail;the structural parameters measurement and calculation of the failed samples were completed.(2)The simulation model of hydraulic control system was built by AMESim simulation software.The parameters of the simulation model were set according to the measured actual data and working parameters.The bench test was carried out.The consistency between the measured and simulated curves was compared.And the accuracy of the built simulation model was verified.(3)The dynamic characteristics of the main pressure valve,clutch control valve and clutch hydraulic cylinder in the vehicle switching drive mode were analyzed by using the clutch hydraulic control system simulation model.The sensitive structural parameters that affect the clutch engagement characteristics were explored: the viscous friction coefficient of the main pressure valve,the viscous friction coefficient of the clutch control valve,the spring stiffness of the clutch control valve,the circulation diameter of the spring cavity of the clutch control valve,the liquid elastic modulus,piston and push rod conversion mass and return spring stiffness.(4)Through the multi-factor orthogonal test method,the influence degree of each structural parameter on the clutch engagement working characteristics was analyzed,and the optimal parameter combination was determined.The simulation curves before and after the improvement of the dynamic characteristics of the hydraulic system were compared.During the clutch engagement process,the piston piston acceleration peak value was reduced by 36.2%,and the stabilization time was reduced by 20.8%.The fluctuation in the sliding stage was significantly reduced.The jitter phenomenon when the clutch was engaged was effectively suppressed.(5)The bench test verification of the improved system was completed.The test results showed that the improved clutch pressure overshoot was reduced by 13.3%,and the pressure fluctuation amplitude of the clutch slip phase was significantly reduced. |
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