Dynamic Characteristics of CVT Electro-Hydraulic Control Valves Including Shift Dynamics 2000-05-0131

Dynamic characteristics of a line regulator and ratio control valve for an electronic controlled metal belt CVT are investigated by considering the CVT shift dynamics. Based on the dynamic models of the variable force solenoid valve, line regular valve and ratio control valve, simulations are performed and compared with the test results. It is seen that the ratio control valve has a on-off characteristics, which may result in a pressure pulsation in the primary actuator. In addition, the effects of the orifice size at the ratio control valve exhaust port are investigated. It is found that as the orifice size is decreased, magnitude of the residual pressure increases, which ensures the belt clamping force to transmit a large torque during the downshift at the cost of slow shifting. It is expected that the dynamic models of the CVT hydraulic system obtained in this study can be used in design of a prototype CVT