Variable displacement vane pump

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 the vane slides by rotation of the rotor and being made eccentric to a center 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, thereby changing a discharge displacement of the pump chamber, the variable displacement vane pump comprising:

• a first fluid pressure chamber and a second fluid pressure chamber which are defined in an accommodating space in the outer periphery of the cam ring, wherein the cam ring is made eccentric to the rotor by a pressure difference between the first fluid pressure chamber and the second fluid pressure chamber;
• 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 the eccentric amount of the cam ring to the rotor becomes small with an increase in a rotation speed of the rotor;
• and
• a flow amount limiting member for limiting a discharge flow amount of the operating fluid in the second fluid pressure chamber at the time the eccentric amount of the cam ring to the rotor becomes small by supplying the operating fluid to the first fluid pressure chamber and discharging the operating fluid from the second fluid pressure chamber.