| 摘要 |
<p>A hydraulic pressure control circuit having a pressure-boosting opening/closing valve mechanism for supplying a control pressure from a hydraulic pressure source to a predetermined actuator, and a pressure-reducing opening/closing valve mechanism for discharging the control pressure from the actuator to a drain location; wherein the pressure-reducing opening/closing valve mechanism has: a valve body; a movable body for actuating the valve body to open/close; an input port for causing the control pressure of the actuator to act on the movable body so as to actuate the valve body in the open-valve direction; a back pressure port for causing a back pressure to act on the movable body so as to actuate the valve body in the close-valve direction; a communicating path communicating between the input port and the back pressure port; a signal pressure generation mechanism provided to the communicating path and having a variable orifice mechanism capable of changing the opening area, the signal pressure generation mechanism communicating with the back pressure port and causing the back pressure to decrease; and a coupling mechanism for changing the opening area of the variable orifice so as to reduce the opening area of the variable orifice mechanism in a state in which the pressure-boosting opening/closing valve mechanism has closed the supply oil path, and increase the opening area of the variable orifice mechanism in a state in which the pressure-boosting opening/closing valve mechanism has opened the supply oil path.</p> |
