| 摘要 |
An object of the present invention is to enhance the capacity of a turbomolecular pump. A turbomolecular pump is a composite-type vacuum pump that combines a blade portion and a thread groove portion. Openings are formed at a joint portion between a rotor blade holding portion that holds rotor blades and a stepped portion that holds a rotor cylinder portion, such that the openings span both the rotor blade holding portion and the stepped portion. Part of the gas that is evacuated by the blade portions is evacuated by a thread groove portion that is formed of the rotor cylinder portion and a stator thread groove, and the rest of the gas is led into the rotor cylinder portion via the openings, and is evacuated by a thread groove portion that is formed of the rotor cylinder portion and another stator thread groove. Stress derived from rotation of a rotor can be withstood when the openings are formed at the joint portion between the rotor blade holding portion and the stepped portion. Moreover, a groove in which a balancer weight is disposed is provided at a clearance portion that lies further on the inlet port side of the other stator thread groove, thereby eliminating the necessity of shortening the length of the other stator thread groove. |
