Pump device

Abstract

A pump device includes a flow control valve that returns a part of working fluid discharged from a pump to the suction side, and the flow control valve includes a valve body, a first fluid pressure chamber that is provided so as to face against a first-side end surface of the valve body and that is communicated with a discharge channel, a second fluid pressure chamber that is provided so as to face against a second-side end surface of the valve body and that is communicated with the discharge channel, a biasing member that is accommodated in the second fluid pressure chamber for biasing the valve body in the valve-closing direction, and a pressure regulator that is provided in a communicating passage through which the discharge channel is communicated with the second fluid pressure chamber and that adjusts pressure in the second fluid pressure chamber.

1 . A pump device for supplying working fluid to a fluid pressure apparatus comprising:
 a pump configured to discharge the working fluid into a discharge channel by sucking and pressurizing the working fluid; and   a flow control valve configured to return a part of the working fluid discharged from the pump to a suction side; wherein the flow control valve comprises:   a valve body;   a first fluid pressure chamber provided so as to face against a first-side end surface of the valve body, the first fluid pressure chamber being communicated with the discharge channel;   a second fluid pressure chamber provided so as to face against a second-side end surface of the valve body, the second fluid pressure chamber being communicated with the discharge channel;   a biasing member accommodated in the second fluid pressure chamber in a compressed state for biasing the valve body in a valve-closing direction;   and a pressure regulator provided in a communicating passage through which the discharge channel is communicated with the second fluid pressure chamber, the pressure regulator being configured to adjust pressure in the second fluid pressure chamber.   
     
     
         2 . The pump device according to  claim 1 , wherein
 the pressure regulator further comprises:   an orifice provided in the communicating passage; and   a relief valve provided in a relief passage branched off from the communicating passage at a downstream side of the orifice, the relief valve being capable of changing a relief pressure.   
     
     
         3 . The pump device according to  claim 2 , wherein
 the relief valve further comprises a proportional solenoid that is capable of changing the relief pressure.   
     
     
         4 . The pump device according to  claim 2 , wherein
 the relief valve is configured to change the relief pressure in accordance with a rotation speed of the pump.   
     
     
         5 . The pump device according to  claim 2 , wherein
 the relief valve is configured to change the relief pressure in accordance with a pressure required by the fluid pressure apparatus.