Patent ID: 8562316

Claim:
A variable capacity vane pump comprising: a pump body; a driving shaft rotatably supported by the pump body; a rotor provided in the pump body and rotatably driven by the driving shaft; a plurality of vanes radially extendably installed in their respective slots that are arranged in a circumferential direction in the rotor; a cam ring rockably provided on a supporting surface with a rock fulcrum being a center in the pump body and formed into a ring shape also forming a plurality of pump chambers at an inner circumference side of the cam ring in cooperation with the rotor and the vanes; first and second members provided at both sides in an axial direction of the cam ring; an inlet port provided at at least one of the first and second members and opening to a section of the pump chamber where a volume of the pump chamber increases; an outlet port provided at at least one of the first and second members and opening to a section of the pump chamber where the volume of the pump chamber decreases; and a seal member provided at an outer circumference side of the cam ring and defining a first hydraulic pressure chamber located at a side where a pump discharge amount increases and a second hydraulic pressure chamber located at a side where the pump discharge amount decreases in a space outside the outer circumference of the cam ring, a space between adjacent vanes of the plurality of vanes being 1 pitch, wherein a port reference line connects a half-pitch-advanced position from an end edge of the inlet port or from an end edge of the outlet port and a center of the driving shaft in a no-load state, a high pressure cam profile reference line connects a center of the cam ring inner circumference side and the center of the driving shaft at a high pressure when an eccentricity amount of the cam ring is a maximum, and a low pressure cam profile reference line connects the center of the cam ring inner circumference side and the center of the driving shaft at a low pressure when the eccentricity amount of the cam ring is a minimum, and the supporting surface supporting the cam ring in the pump body is provided so as to gradually separate from the port reference line in a direction from the first hydraulic pressure chamber to the second hydraulic pressure chamber so that the port reference line, the high pressure cam profile reference line and the low pressure cam profile reference line are set to be substantially parallel to each other.