| 摘要 |
PURPOSE:To provide a hydraulic conflux circuit including a variable-capacity pump and a fixed-capacity pump which can overcome the disadvantage that an actuator once stops when both pumps are turned to be on-load from the condition where only the variable pump is on-load. CONSTITUTION:A three-position solenoid switching valve 5 is mounted as flow rate adjusting means on a line 4 between an actuator 6 and a variable-capacity pump 1 of an injection cylinder in an injection molding machine. A control unit 82 comprising a load sensing valve 25 and a pressure control pilot valve 26 is connected to the line. When the pressure is increased before and behind the valve 5 and a differential pressure between a pilot chamber 29 and a spring chamber 27 of the valve 25 reaches more than a fixed value, the control unit 82 causes fluid pressure to work upon a discharge quantity control portion 36 of the pump 1 to decrease the discharge quantity. A spring chamber 65 of a relief valve 55 connected to a discharge line 51 of a fixed-capacity pump 3 is connected to a spring chamber 30 of a valve 26 through a switching valve 60. |
