Patent ID: 8342817
Filing Date: 2013-01-01
Classification: F04C

Abstract:
1. 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; a first fluid pressure passage communicated with the first fluid pressure chamber; a second fluid pressure passage communicated with the second fluid pressure chamber; and a flow amount limiting member for limiting a discharge flow amount of the operating fluid from the second fluid pressure chamber to a drain passage 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 through the first fluid pressure passage and discharging the operating fluid from the second fluid pressure chamber to the drain passage through the second fluid pressure passage.