| 摘要 |
PURPOSE:To reduce the pressure lowering time and a surge pressure by providing a throttle element at the entrance side of an inverse check valve provided on a discharge line in parallel to a check valve, and providing an escape valve operated by the pressure difference generated to the throttle element. CONSTITUTION:In ducts 20 and 21 to be the discharge line of a pump element 2, a check valve 1b to allow only the free flow from a discharge side to a load side is provided. And an inverse check valve 17 in parallel to the check valve 16 to allow only the free flow from the load side to the pump element side is provided. And a throttle element 18 is provided at the entrance side of the inverse check valve 17, and an escape valve 19 to communicate the pump discharge pressure to a tank 26 by the pressure difference generated to the throttle element 18 is provided. As a result, even though the load capacity is increased in a pressure lowering control time, the pressure lowering time is not made longer. And by operating the escape valve 19 instantly when the flow controlling is converted to the pressure controlling, the generation of a surge pressure by the delay of response can be suppressed. |
