| 摘要 |
PURPOSE:To prevent the transient shortage of an operating fluid by moving a spool on the basis of the operation of a change-over valve in the case of the rotating speed of a vane pump being below the specified value, and holding the spool into a position for communicating a first port with a second port when the rotating speed of the vane pump becoming over the specified value. CONSTITUTION:A solenoid valve 40 is operated by a control device 41 on the basis of input from a vehicle speed sensor 42, and when steering is performed at the open time of the solenoid valve 40 with the rotating speed of a vane pump 10 being below the specified value, the delivery pressure of the vane pump 10 is increased, and the pressure led into a pressure receiving chamber 33 from a pressure lead-in port 37 is increased, so that a spool 32 is moved to the right to cut off a communicating passage 53 from a reflux passage 52 and to switch-communicate the communicating passage 53 with a second intake passage 50b. A second intake port 12b thereby sucks an operating fluid from a tank 59, and this operating fluid is added to an operating fluid in an operating fluid delivery passage 52 from a second delivery port 13b so as to increase the delivery flow from the vane pump 10. |
