Vane pump

A vane pump comprising:

• a rotor having a plurality of slits formed in a radiating pattern, the rotor being rotationally driven;
• a plurality of vanes freely slidably received in the slits;
• a cam ring having a cam face with which tip end portions of the vanes come into sliding contact;
• a side member having a sliding contact surface with which side surfaces of the rotor and the vanes come into sliding contact;
• pump chambers defined by the rotor, the cam ring, and the adjacent vanes;
• a suction port configured to open in the sliding contact surface, the suction port being configured to guide working fluid to be sucked into the pump chambers;
• a discharge port configured to open in the sliding contact surface, the discharge port being configured to guide the working fluid discharged from the pump chambers;
• groove-shaped notches provided in the side member so as to extend from an end portion of the discharge port in a direction opposite from a forward rotation direction of the rotor;
• and
• back pressure chambers defined with base-end portions of the vanes in the slits, wherein
• the notches includes:
• an inner notch located at an inner side of the end portion of the discharge port in a radial direction;
• and
• an outer notch located at an outer side of the end portion of the discharge port in the radial direction, and
• the side member has a tip-end-side guide surface provided between the inner notch and the outer notch so as to be continuous from the end portion of the discharge port, the tip-end-side guide surface being configured to push the tip end portions of the vanes upward and guides them toward the sliding contact surface of the side member when the rotor is rotated in a reverse rotation direction.