Patent ID: 9388816
Filing Date: 2016-07-12
CPC Classification: F04D

Claim Text:
1. A turbomolecular pump, comprising: a casing; an inner cylinder disposed in a center of the casing; a rotor rotatably supported in the inner cylinder, and having a first cylinder portion formed on an inlet port side, rotor blades that are formed from the first cylinder portion towards an inner peripheral face of the casing, a second cylinder portion formed at a lower end of the first cylinder portion and having a larger outer diameter than that of the first cylinder portion, and a stepped portion that joins the lower end of the first cylinder portion and an upper end of the second cylinder portion; stator blades fixed to the casing and formed corresponding to the rotor blades; a first thread groove portion formed between an outer side of the second cylinder portion and an inner side of the casing; and a second thread groove portion formed between an inner side of the second cylinder portion and the inner cylinder, wherein opening portions are formed at a joint portion of the first cylinder portion and the stepped portion, the opening portions are formed in both the first cylinder portion and the stepped portion.