VACUUM PUMP

摘要

PROBLEM TO BE SOLVED: To provide a vacuum pump which can prevent a jumping phenomenon of a broken rotor and resultant changes in the positional relationship between the rotor and a rigid ring or a cushion, and reliably reduce the breaking torque. SOLUTION: The rigid ring 10 of the shape surrounding an entire screw stator 7 is installed on an outer side of the screw stator 7 as a screw stator reinforcing means to increase the strength of an upper side 7a of the screw stator 7 compared with the strength of a lower side 7b thereof so that the deformation resistance of the rigid ring 10 is large on the upper side 7a of the screw stator 7 and smaller on the lower side 7b. More specifically, the wall thickness of the rigid ring 10 is formed to be larger on the upper side 7a of the screw stator 7 and smaller on the lower side 7b thereof.