Patent ID: 6688863
Filing Date: 2004-02-10
Classification: F04C

Abstract:
A vacuum pump that draws gas by operating a gas conveying body in a pump chamber through rotation of a horizontal rotary shaft, the vacuum pump comprising:an oil housing member, wherein the oil housing member defines an oil zone adjacent to the pump chamber, and the rotary shaft has a projecting portion that projects from the pump chamber into the oil zone through the oil housing member; a stopper having a circumferential surface, wherein the stopper is located on the rotary shaft to rotate integrally with the rotary shaft and prevents oil from entering the pump chamber; and a circumferential wall surface, the center of curvature of which coinciding with that of the rotary shaft, wherein the circumferential wall surface surrounds at least a part of the circumferential surface of the stopper that is above the rotary shaft, and wherein the circumferential wall surface that is above the rotary shaft is inclined downward from the pump chamber to the oil zone such that the distance between the circumferential wall surface and the axis of the rotary shaft decreases toward the oil zone.