Patent ID: 8348646

Claim:
A variable displacement vane pump having a rotor connected to a drive shaft, a plurality of vanes provided in the rotor so as to be capable of reciprocating in a diameter direction of the rotor, a cam ring for accommodating the rotor therein, the cam ring having a cam face in an inner surface thereof on which a front portion of each of the vanes slides by rotation of the rotor, and a pump chamber defined between the rotor and the cam ring, wherein an eccentric amount of the cam ring to the rotor changes to change a discharge displacement of the pump chamber, the variable displacement vane pump comprising: a pump body configured to accommodate the cam ring therein; a first fluid pressure chamber and a second fluid pressure chamber, wherein the cam ring is made eccentric to the rotor only by a pressure difference between the first fluid pressure chamber and the second fluid pressure chamber; an adapter ring configured to define the first fluid pressure chamber and the second fluid pressure chamber between the adapter ring and an outer peripheral surface of the cam ring; a control valve which operates in response to a pump discharge pressure for controlling a pressure of an operating fluid in each of the first fluid pressure chamber and the second fluid pressure chamber in such a manner that an eccentric amount of the cam ring to the rotor becomes small with an increase in a rotation speed of the rotor; a pressure applying section configured to apply a pressure to the cam ring in a direction of increasing the eccentric amount of the cam ring to the rotor by continuously introducing the operating fluid discharged from the pump chamber into the second fluid pressure chamber; and a cam ring movement restricting portion formed in the second fluid pressure chamber and configured to define a minimum eccentric amount of the cam ring by restricting the movement of the cam ring in a direction of decreasing the eccentric amount of the cam ring to the rotor; wherein the cam ring movement restricting portion includes a swelling portion formed on an inner peripheral surface of the adapter ring or on the outer peripheral surface of the cam ring.