Multi-vane type compressor

Claim 1

A multi-vane type compressor comprising: a cylinder formed with at least a suction port and at least a discharge port; a front head having a flat face for closing one end of said cylinder; a rear head having a flat face for closing the other end of said cylinder; a rotor arranged in said cylinder, said rotor having a peripheral surface, flat opposite end surface juxtaposed against said faces respectively, and a plurality of vane grooves opening in said peripheral surface and said opposite end surfaces; a plurality of vanes each slidably inserted in one of said plurality of vane grooves, each said vane defining by its end surface and the bottom of the associated vane groove a vane back pressure space; means for defining first supply groove on at least one of the faces of said front head and said rear head, said first supply groove being in fluid connection with the vane back pressure spaces of the vanes in the suction stroke; first passage means (14) for exposing said first supply groove to the suction gas pressure; means for defining second supply groove on at least one of the faces of said front head and said rear head, said second supply groove being in fluid connection with the vane back pressure spaces of the vanes in the discharge stroke, said second supply groove including a trailing side portion (13a) disposed posteriorly with respect to the direction of movement of the vanes and a leading side portion (13b) disposed anteriorly with respect thereto; second passage means (15) for exposing said trailing side portions (13a) to the discharge gas pressure; and third passage means (16, 17, 13b') for exposing said leading side portions (13b) to the discharge gas pressure: said third passage means having throttling function with respect to the fluid flowing therethrough, whereby a pressure higher than the discharge gas pressure can be produced in the vane back pressure spaces when the vanes are forced into the vane grooves.