| 摘要 |
PURPOSE:To keep the pump discharge flow rate constant in a load-sensitive type fluid control unit by connecting a spring chamber of a regulator of a variable- capacity pump and an auxiliary pump with a pipeline and disposing a pressure control valve in the pipeline. CONSTITUTION:A variable-capacity pump 33 is adapted to supply pressurized oil to a hydraulic actuator 32 through a flow rate control valve 35 and a direction changing valve 37. The discharge flow rate of the pump is changed by a regulator 34. Pressurized oil is supplied and discharged to and from a head chamber 34c of the regulator 34 through a pressure control switching valve 43, the opening of which is controlled according to a differential pressure between before and behind a fixed throttle 39 in a branch pipeline 38 or through a flow rate control switching valve 42, the opening of which is controlled according to a differential pressure between before and behind the flow rate control valve 35. In this case, a newly mounted auxiliary pump 53 and a spring chamber 34e of the regulator 34 are connected to each other by a discharge pipeline 55 where a pressure control valve 54 is disposed, and a vent port of the pressure control valve 54 and a discharge pipeline of a pump 33 are connected to each other by a vent path 56. |
