Vane pump

Abstract

A vane pump includes a cam ring, a rotor, a plurality of vane, and a lateral plate. The lateral plate has an extension groove. The shape of a pump chamber forming surface viewed from the rotation-axis direction of the rotor satisfies the following requirements i) and ii) at the time when a first vane passes the base end part of the extension groove: i) the center line of the groove width of the extension groove is inclined from the radial direction of the rotor; and ii) a slit in which a second vane is accommodated has an open end falling within a belt-shaped range obtained by extending a groove width of the base end part of the extension groove along a virtual extension line.

What is claimed is: 
     
         1 . A vane pump comprising:
 a cam ring having a cam surface on an inner peripheral surface of the cam ring, the cam ring forming a rotor chamber;   a rotor configured to rotate in a predetermined rotation direction inside the rotor chamber, the rotor including a plurality of slits formed in a radial manner to extend radially outwardly from a central part of the rotor;   a plurality of vanes provided such that the vanes are accommodated in the slits, respectively, and rotate together with the rotor, the vanes being configured to define a plurality of pump chambers between the cam surface and an outer peripheral surface of the rotor; and   a lateral plate having a flat pump chamber forming surface facing the pump chambers, the lateral plate being configured such that an inlet port via which a fluid is taken into the rotor chamber and a discharge port via which the fluid taken into the rotor chamber is discharged are opened on the pump chamber forming surface, wherein:   the lateral plate has an extension groove extended rearward in the rotation direction from the discharge port, the extension groove having a groove width gradually narrowed from a base end part, on the discharge port side, of the extension groove toward a distal end part of the extension groove;   at a time when a first vane out of paired vanes defining a pump chamber communicating with the extension groove, the first vane being on a front side in the rotation direction of the rotor, passes the base end part of the extension groove, the pump chamber forming surface viewed from a rotation-axis direction of the rotor has a shape satisfying the following requirements i) and ii),
 i) a center line of the groove width of the extension groove is inclined from a radial direction of the rotor such that the center line approaches a rotation axis of the rotor on the distal end part side rather than the base end part side, and 
 ii) among the slits, a slit in which a second vane out of the paired vanes, the second vane being on a rear side in the rotation direction, is accommodated has an open end falling within a belt-shaped range obtained by extending a groove width of the base end part of the extension groove along a virtual extension line obtained by further extending a center line of the groove width of the extension groove from the distal end part. 
   
     
     
         2 . The vane pump according to  claim 1 , wherein the shape of the pump chamber forming surface viewed from the rotation-axis direction of the rotor further satisfies the following requirement iii) at the time when the first vane passes the base end part of the extension groove,
 iii) the virtual extension line does not intersect with the rotor between the first vane and the second vane.   
     
     
         3 . The vane pump according to  claim 1 , wherein the shape of the pump chamber forming surface viewed from the rotation-axis direction of the rotor further satisfies the following requirement iv) at the time when the first vane passes the base end part of the extension groove,
 iv) among angles formed between the virtual extension line and the second vane, an angle on the first vane side and on the cam surface side falls within a range of 90°±10°.   
     
     
         4 . The vane pump according to  claim 1 , wherein:
 an opening peripheral part of each of the slits in the rotor is formed as a protrusion projecting radially outwardly from a circumferential central part between two adjacent slits among the slits; and   the shape of the pump chamber forming surface viewed from the rotation-axis direction of the rotor further satisfies the following requirement v) at the time when the first vane passes the base end part of the extension groove,
 v) the distal end part of the extension groove is placed radially outwardly from the opening peripheral part in the radial direction of the rotor.