Oil leak prevention structure of vacuum pump

摘要

A vacuum pump draws gas by operating a gas conveying body in a pump chamber through rotation of a rotary shaft. The vacuum pump has an oil housing member, a stopper and a circumferential wall surface. The oil housing member defines an oil zone adjacent to the pump chamber. The stopper has a circumferential surface. The stopper is located on the rotary shaft to rotate integrally with the rotary shaft and prevents oil from entering the pump chamber. The center of curvature of the circumferential wall surface coincides with that of the rotary shaft. The circumferential wall surface surrounds at least a part of the circumferential surface of the stopper that is above the rotary shaft. The circumferential wall surface is inclined such that the distance between the circumferential wall surface and the axis of the rotary shaft decreases toward the oil zone.