Study On Oil Pressure Buffer Control Of Wet Clutch In Automatic Transmission

Since Automatic Transmission has the advantage of smooth starting, shifting automatically, smooth shifting and so on, it is the most important type in automatic transmission and is used widely in recent years. Its smooth shifting affects vehicle shift quality and comfort. The shifting process of Automatic Transmission is actually the process of wet clutch engagement and disengagement. The rule of oil pressure variation of wet clutch in shifting process needs to be controlled reasonably, which can reduce the dynamic load of the transmission output shaft effectively, reduce shift shock and improve vehicle shift quality.An oil pressure buffer system of wet clutch in Automatic Transmission was designed in this paper. Modeling, simulation analysis and experimental research on the system were carried out. The main contents are as following:(1)The working principle of Automatic Transmission was analyzed and the oil pressure buffer characteristic requirement in shift was obtained by analyzing the influence of clutch oil pressure on shift quality.(2)The wet clutch oil pressure buffer system was designed, which included electromagnetic proportional valve, buffer valve, oil pressure holding valve and other components. The working principle of the system was analyzed. The geometry parameters of the buffer valve and oil pressure holding valve was calculated.(3)The model of wet clutch oil pressure buffer system was established in MATLAB/Simulink. The process of clutch buffering was analyzed The result shows that output oil pressure meets the requirement of the clutch oil pressure buffer characteristic. Some parameters of the system which may affect the buffer characteristic were studied, obtaining the influence of the parameters on the system buffer characteristic.(4)The experimental research on the clutch pressure buffer control system was carried out. The influence of working pressure and oil temperature on the system buffer characteristic was studied. The simulation result is consistent with the experimental result, indicating that the simulation model can reflect the system characteristic and is correct.(5)The simulation model of the clutch engagement process was established. The parameters of the oil pressure buffer system were analyzed on the clutch engagement process.