Variable displacement vane pump

Abstract

A variable displacement vane pump includes: a restrictor configured to impart resistance to flow of working fluid discharged from the pump chambers; a control valve configured to introduce the working fluid which is discharged from the pump chambers to the first fluid pressure chamber as a differential pressure between upstream and downstream of the restrictor is increased, the control valve being configured to discharge the working fluid in the first fluid pressure chamber as the differential pressure between upstream and downstream of the restrictor is reduced; a suction passage configured to guide the working fluid to be sucked into the pump chambers, the suction passage being configured to always communicate with the second fluid pressure chamber; and a guiding passage configured to allow communication between the control valve and the second fluid pressure chamber, the guiding passage being configured to guide the working fluid, which is discharged from the first fluid pressure chamber to the control valve, to the second fluid pressure chamber.

1 . A variable displacement vane pump comprising:
 a rotor linked to a driving shaft;   a plurality of vanes provided so as to be movable in a reciprocating manner in the radial direction with respect to the rotor;   a cam ring in which tip-end portions of the vanes are in sliding contact with a cam face on an inner circumference of the cam ring with rotation of the rotor arranged in the cam ring, the cam ring being capable of being made eccentric with respect to the rotor;   pump chambers defined between the rotor and the cam ring by being partitioned by the plurality of vanes;   a first fluid pressure chamber and a second fluid pressure chamber defined in an accommodating space on an outer circumferential side of the cam ring;   a biasing member configured to always bias the cam ring in a direction in which an amount of eccentricity is increased;   a restrictor configured to impart resistance to flow of working fluid discharged from the pump chambers;   a control valve configured to reduce the amount of eccentricity of the cam ring by introducing the working fluid that has been discharged from the pump chambers to the first fluid pressure chamber as a differential pressure between upstream and downstream of the restrictor is increased, the control valve being configured to increase the amount of eccentricity of the cam ring by discharging the working fluid in the first fluid pressure chamber as the differential pressure between upstream and downstream of the restrictor is reduced;   a suction passage configured to guide the working fluid to be sucked into the pump chambers, the suction passage being configured to always communicate with the second fluid pressure chamber; and   a guiding passage configured to allow communication between the control valve and the second fluid pressure chamber, the guiding passage being configured to guide the working fluid, which is discharged from the first fluid pressure chamber to the control valve, to the second fluid pressure chamber.   
     
     
         2 . The variable displacement vane pump according to  claim 1 , further comprising:
 an adapter ring formed in an annular shape so as to surround the cam ring; and   a pump body that has a recessed portion for accommodating the adapter ring, wherein   the control valve is arranged radially outside of the adapter ring so as to be adjacent to the adapter ring, and   the guiding passage opens at an inner circumferential surface of the adapter ring in the second fluid pressure chamber.   
     
     
         3 . The variable displacement vane pump according to  claim 1 , further comprising
 a pump body that has a recessed portion for accommodating the cam ring and that has the guiding passage formed therein, wherein   the guiding passage opens at a bottom surface of the recessed portion in a suction region in which volumes of the pump chambers are expanded.   
     
     
         4 . The variable displacement vane pump according to  claim 3 , wherein
 the guiding passage has a first guiding passage and a second guiding passage, the first guiding passage opening at the bottom surface of the recessed portion, the first guiding passage being formed in a straight line parallel to the driving shaft, the second guiding passage being configured to connect the first guiding passage and the control valve in a straight line.