| 摘要 |
PROBLEM TO BE SOLVED: To increase compression ratio and exhaust flow rate without narrowing a gap between a stator and a rotor. SOLUTION: The thread groove type vacuum pump 1 is equipped with a cylindrical outside member 2, a column-shaped inside member 3 arranged in the outside member 2 through the medium of a clearance therewith, and a thread groove 4 formed in at least one of the inside peripheral surface of the outside member 2 and the outside peripheral surface of the inside member 3, wherein exhaust is carried out by rotating at least one of the outside member 2 and the inside member 3. In addition, the pump contains a backflow preventing means 5 formed at least in one area of at least one of the outside member 2 and the inside member 3, and a recess 6 formed in the outside member 2 or the inside member 3 opposed to the backflow preventing means 5. COPYRIGHT: (C)2005,JPO&NCIPI
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