| 摘要 |
A hydraulic pressure-control valve (214) for controlling a pressure to be supplied to a frictional engaging element (24) such as a start clutch in an automatic vehicle transmission, including a first pressure-regulating valve connected to a hydraulic pressure source (310) and connected to the frictional engaging element through a second passage, and a solenoid for displacing the first-pressure-regulating valve. A second pressure-regulating valve is provided and is connected to the first pressure-regulating valve to receive the output hydraulic pressure, the first pressure-regulating and the second pressure-regulating valve are connected such that the output hydraulic pressure varies in response to the command input according to a first characteristic, while the output hydraulic pressure varies in response to the command input according to a second characteristic when the command input exceeds a predetermined value, wherein the output hydraulic pressure according to the first characteristic per unit of command input is less than the output hydraulic pressure according the second characteristic, thereby reducing load hysteresis and improving control accuracy in a low pressure region, while enabling to secure high torque capacity in a high pressure region. <IMAGE> |
