Patent ID: 6813301
Filing Date: 2004-11-02
Classification: F04D,F16C

Abstract:
A structure of a reflux fan for an excimer laser apparatus, for circulating laser gas in a chamber by rotation of a fan driven by a motor, comprising:a rotary shaft on which the fan is attached and rotated by a driving force of said motor; a control type magnetic bearing supporting said rotary shaft in a non-contact manner; and a protective bearing supporting the rotary shaft when said control type magnetic bearing is unable to support said rotary shaft; wherein said control type magnetic bearing includes radial magnetic bearings including radial electromagnets arranged at three portions along axial direction and position detection sensors arranged around respective radial electromagnets, and an axial magnetic bearing including one axial electromagnet and at least one permanent magnet; said axial electromagnet is arranged opposing to one end surface of said rotary shaft, and said permanent magnet is arranged opposing to the other end surface of said rotary shaft; and among said radial magnetic bearings, a first radial magnetic bearing is arranged close to said axial electromagnet, a second radial magnetic bearing is arranged nearer to one side of the rotary shaft than the permanent magnet arranged opposing to an end surface of said rotary shaft, and a third radial magnetic bearing is arranged between said motor and said fan.