Patent ID: 8419392

Claim:
A variable displacement vane pump comprising: a pump body; a drive shaft supported by the pump body; a rotor which is disposed in the pump body, which is driven by the drive shaft, which is formed with a plurality of slots in a circumferential direction, and which is provided with a plurality of vanes each slidably received in one of the slots; an annular cam ring receiving therein the rotor rotatably, the cam ring being disposed in the pump body, and arranged to swing about a swing axis, and to define a plurality of pump chambers with the vanes between the rotor and the cam ring; a rear body closing the pump body; a pressure plate received in the pump body, the pressure plate including a through hole receiving the drive shaft, and being arranged to be urged to the rotor by receiving an outlet pressure in an axial direction; inlet ports formed in the rear body and the pressure plate, and opened in a region in which volumes of the pump chambers are increased; outlet ports formed in the rear body and the pressure plate, and opened in a region in which the volumes of the pump chambers are decreased; first and second fluid pressure chambers formed radially outside the cam ring, and arranged to control an eccentric quantity of the cam ring; a pressure control device arranged to control a pressure introduced to one of the first fluid pressure chamber and the second fluid pressure chamber; an inlet passage formed in one of the pump body and the rear body, and connected with a reservoir tank storing the hydraulic fluid; a low pressure supply passage constantly connecting the inlet passage and the other of the first fluid pressure chamber and the second fluid pressure chamber; a low pressure introduction port formed in the other of the pump body and the rear body, and opened in the other of the first fluid pressure chamber and the second fluid pressure chamber; and a low pressure introduction passage formed in the other of the pump body and the rear body, the low pressure introduction passage connecting the low pressure introduction port and the inlet ports.