Vane pump

Abstract

A vane pump in which oil is drawn from at least one side, in an axial direction, of a cam ring and is discharged from at least one side, in the axial direction, of the cam ring, has a portion defined by a groove formed on an inner circumference surface of the cam ring. The groove extends along a circumferential direction of the inner circumference surface of the cam ring and is arranged in a position including a middle of an axial direction width on the inner circumference surface. The groove is arranged in an oil suction section or an oil discharge section of the cam ring.

1 . A vane pump in which oil is drawn from at least one side, in an axial direction, of a cam ring and is discharged from at least one side, in the axial direction, of the cam ring, the vane pump comprising:
 a portion defined by a groove formed on an inner circumference surface of the cam ring, the groove extending along a circumferential direction of the inner circumference surface and arranged in a position including a middle of an axial direction width on the inner circumference surface in an oil suction section or an oil discharge section of the cam ring.   
     
     
         2 . The vane pump as claimed in  claim 1 , wherein:
 the groove is formed so that a depth of the groove is gradually shallower from a middle, in the circumferential direction, of the groove to both ends of the groove.   
     
     
         3 . The vane pump as claimed in  claim 1 , wherein:
 the groove is formed by cutting.   
     
     
         4 . The vane pump as claimed in  claim 1 , wherein:
 the groove is provided in both of the oil suction section and the oil discharge section on the inner circumference surface of the cam ring.   
     
     
         5 . The vane pump as claimed in  claim 1 , wherein:
 the vane pump is a vane pump in which the oil is drawn from both sides, in the axial direction, of the cam ring and is discharged from both sides, in the axial direction, of the cam ring, and   the groove is formed at a circumferential portion except both circumferential edge sides of the axial direction width on the inner circumference surface of the cam ring.   
     
     
         6 . The vane pump as claimed in  claim 5 , wherein:
 widths of the both circumferential edge sides of the axial direction width on the inner circumference surface, where no groove exists, are set to be substantially the same.   
     
     
         7 . A vane pump comprising:
 a rotor rotatably driven;   a plurality of vanes arranged at an outer circumference of the rotor and extending/retracting in a radial direction;   a cam ring housing, at an inner circumferential side thereof, the rotor and the vanes, the extending/retracting movement of the vanes occurring by the rotation of the rotor and sliding contact of each top end edge of the vanes with an inner circumference surface of the cam ring;   a housing housing the cam ring inside the housing and defining a plurality of pump chambers by the housing, the vanes, the cam ring and the rotor;   an inlet port provided at least one side of both side walls of the housing which respectively face axial direction both sides of the cam ring and opening to a section where the vanes extend;   an outlet port provided at least one side of the both side walls of the housing which respectively face the axial direction both sides of the cam ring and opening to a section where the vanes retract; and   a communication portion formed at a circumferential portion except both circumferential edge sides of an axial direction width on the inner circumference surface of the cam ring in the section where the vanes extend and connecting the pump chambers.   
     
     
         8 . The vane pump as claimed in  claim 7 , wherein:
 the communication portion is formed by a groove that extends in a circumferential direction of the inner circumference surface of the cam ring.   
     
     
         9 . The vane pump as claimed in  claim 8 , wherein:
 the groove is formed so that depths of both ends of the groove is shallower than that of a middle, in the circumferential direction, of the groove.   
     
     
         10 . The vane pump as claimed in  claim 8 , wherein:
 the cam ring moves with respect to the rotor and an eccentric amount of the cam ring with respect to the rotor changes, and an oil amount discharged from the outlet port is varied by the change of the eccentric amount.   
     
     
         11 . The vane pump as claimed in  claim 10 , wherein:
 the cam ring is forced in a direction in which the eccentric amount with respect to the rotor becomes large by a forcing member, and   the cam ring is moved in an opposite direction against the force of the forcing member, for controlling the oil discharge amount.   
     
     
         12 . The vane pump as claimed in  claim 11 , wherein:
 the cam ring is configured to move in the opposite direction by receiving a pressure of the outlet port.   
     
     
         13 . The vane pump as claimed in  claim 7 , wherein:
 the communication portion is formed by a communication conduit.   
     
     
         14 . A vane pump comprising:
 a rotor rotatably driven and having, at an outer circumference thereof, a plurality of opening slots;   a plurality of vanes provided in the respective slots;   a cam ring housing, at an inner circumferential side thereof, the rotor and the vanes, extending/retracting movement of the vanes at the outer circumference of the rotor occurring by the rotation of the rotor;   a housing housing the cam ring inside the housing and defining a plurality of pump chambers by the housing, the vanes, the cam ring and the rotor;   an inlet port provided at least one side of both side walls of the housing which respectively face axial direction both sides of the cam ring and opening to a section where a volume of the pump chamber increases;   an outlet port provided at least one side of the both side walls of the housing which respectively face the axial direction both sides of the cam ring and opening to a section where the volume of the pump chamber decreases; and   a communication portion formed at a circumferential portion except both circumferential edge sides of an axial direction width on an inner circumference surface of the cam ring in the section where the volume of the pump chamber decreases and connecting the pump chambers.   
     
     
         15 . The vane pump as claimed in  claim 14 , wherein:
 the cam ring moves with respect to the rotor and an eccentric amount of the cam ring with respect to the rotor changes, and an oil amount discharged from the outlet port is varied by the change of the eccentric amount.