Patent ID: 8449277

Claim:
A vane pump comprising: a housing comprising a substantially circular pump chamber; a rotor that rotates about a position eccentric with respect to a center of the pump chamber; a vane that is rotated by the rotor and that always partitions the pump chamber into a plurality of spaces; an oil supply passage that intermittently communicates with the pump chamber by the rotation of the rotor; an oil supply pipe that is connected to the oil supply passage to supply a lubricating oil from a hydraulic pump thereto; and a gas passage that makes the pump chamber and an outer space communicate with each other when the oil supply passage communicates with the pump chamber by the rotation of the rotor, wherein the oil supply passage comprises a diameter direction oil supply hole provided at a shaft part of the rotor in a diameter direction thereof; and an axial direction oil supply groove that is provided in the housing to communicate with the pump chamber, and with which an opening of the diameter direction oil supply hole is made to intermittently overlappingly communicate by the rotation of the rotor, and the gas passage comprises a diameter direction gas hole that is provided at the shaft part of the rotor in the diameter direction thereof to communicate with the oil supply passage; and an axial direction gas groove that is provided in the housing to communicate with the outer space, and with which an opening of the diameter direction gas hole is made to intermittently overlappingly communicate by the rotation of the rotor, and the diameter direction gas hole is made to communicate with the axial direction gas groove when the diameter direction oil supply hole is made to communicate with the axial direction oil supply groove, when a passage area of the gas passage is defined as S 1 , a passage area of the oil supply passage is S 2 , a passage area of the oil supply pipe is S 3 , a diameter of the diameter direction oil supply hole is d 2 , and a width of the axial direction oil supply groove in a rotational direction of the rotor is L, the passage area S 2 of the oil supply passage is set to be greater than the passage area S 1 of the gas passage, and not greater than three times the passage area S 2 such that a required lubricating oil is made to be reliably supplied in the pump chamber via the oil supply passage, the passage area S 3 of the oil supply pipe is set to be greater than the passage area S 2 of the oil supply passage, and in a range between two and three times the passage area of S 2 , inclusive such that a hydraulic pressure of the oil supply passage is kept high due to a squeezing effect, and the width L of the axial direction oil supply groove is set to be greater than the diameter of the diameter direction oil supply hole d 2 to suppress sucking of the air in the pump chamber when a hydraulic pressure of the oil supply passage is low.