| 摘要 |
PURPOSE:To contrive the improvement of safety in a line pressure control by providing a pressure relief part, switching the control to a feedforward control from a feedback control when a line pressure exceeds an upper limit value, in a pressure regulator valve. CONSTITUTION:A pressure regulator valve 17 supplies the amount of a line pressure PL from a variable displacement pump 10 exceeding a predetermined value to a feedback control mechanism (control cylinder) 24 as the feedback pressure from a port 17d, performing a feedback control of the line pressure. Here in response to a rapid change of modifier pressure PM, when the line pressure PL exceeds an upper limit value of the feedback control, the valve 17 lowers against a spring 20, connecting a pressure relief part 17f to partly communicate with a port 17b, closing the port 17d, switching the feedback control to a feedforward control and cutting an overshoot of the line pressure. Thus while ensuring responsibility of the control to vibration of the line pressure, the line pressure control of safety can be attained. |
