SHAFT SEAL DUSTPROOF STRUCTURE OF TURBO MOLECULAR DRAG PUMP

摘要

A shaft seal dustproof structure of a turbo molecular pump that evacuates corrosive gas or gas containing fine particles such as dust, capable of preventing intrusion of corrosive gas or fine particles into the motor housing of the turbo molecular pump. In the turbo molecular drag pump where a purge gas supply port (5a) is provided in the motor housing (5), a shaft seal section consisting of a clearance seal portion (3a) provided at the outer circumferential part of a boss (1b) projecting to the central part of the disc (1a) of a rotor (1), and a centrifugal blade dustproof portion (3b) having a centrifugal blade (1c) provided on the surface of the disc (1a) is provided in a purge gas passage leading to a pump chamber (8) from the motor housing (5).