| 摘要 |
PROBLEM TO BE SOLVED: To supply and suck the gas without providing a hole in a vacuum chamber by exposing a part of a housing fitted to a fixed base out of the vacuum chamber, and connecting a gas supplying passage of a gas bearing to a gas supplying device at the exposed part, and connecting a gas suction passage communicated with a seal clearance to a gas suction device at the exposed part. SOLUTION: A housing 6 is inserted into a fitting hole 8 of a fixed base 1, and a fixing flange 7 and the fixed base 1 are fixed to each other through a seal member 9. A part surrounded by the outside of the seal member 9 and a vacuum chamber 2 is held in the vacuum condition, but the housing 6 part is exposed outside of the vacuum chamber 2. Gas is supplied from a gas supplying device 4, and fed to a clearance between bearings 15, 15', 16 and a rotary shaft 12 so as to form a static pressure gas bearing. The gas discharged from the static pressure gas bearing is collected to a seal groove 21 of a seal clearance 20, and sucked to a gas suction device 5 through a gas suction passage 28, a discharged gas reservoir 24 and a housing passage 25. With this structure, a necessity of passing gas supplying and sucking pipelines through a bulkhead of the vacuum chamber and a necessity of sealing at a high accuracy are eliminated.
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