Abstract: A variable displacement vane pump that assuredly suppresses seizing of mutually contacting surfaces of a pressure plate and a rotor where the pressure plate is formed, at one side surface thereof that slidably contacts the rotor, with an annular lubricating groove. The lubricating groove is on a seal surface of the side surface at a position between arcuate back pressure grooves formed on the seal surface and a through opening which is formed in a center part of the pressure plate to receive the drive shaft. A radial width of the lubricating groove is set to a range from 10% to 25% of a radial width of the seal surface, and a distance from a center of the radial width of the lubricating groove to an inner cylindrical surface of the through opening is set to a range from 24% to 70% of the radial width of the seal surface.

Abstract: A variable displacement vane pump includes a rotor, a cam ring; and a pump casing including first and second side walls disposed on both sides of the cam ring, and a circumferential wall surrounding the cam ring and defining first and second pressure chambers. A pressure introduction groove is formed in a sliding contact surface between the cam ring and one of the first and second side walls, and arranged so that a pressure lower than an outlet pressure is introduced.

Abstract: [Task] To provide a variable displacement vane pump that assuredly suppresses seizing of mutually contacting surfaces of a pressure plate and a rotor. [Means for Achieving the Task] In this variable displacement vane pump, pump elements, such as a drive shaft 7, a rotor 8 and a pressure plate 11 are installed in a receiving space 2a of a front body 2, and an open side of the receiving space 2a is closed by a rear body 3. The pressure plate is formed, at one side surface thereof that slidably contacts the rotor, with an annular lubricating groove 44, the lubricating groove 44 being provided on a seal surface 43 of the side surface at a position between each of arcuate back pressure grooves 41 and 42 which are formed on the seal surface 43 and a through opening 26 which is formed in a center part of the pressure plate to receive the drive shaft.

Abstract: A variable displacement vane pump includes a rotor, a cam ring; and a pump casing including first and second side walls disposed on both sides of the cam ring, and a circumferential wall surrounding the cam ring and defining first and second pressure chambers. A pressure introduction groove is formed in a sliding contact surface between the cam ring and one of the first and second side walls, and arranged so that a pressure lower than an outlet pressure is introduced.