| 摘要 |
PURPOSE:To prevent the clogging of an exhaust passage due to the sedimentation of the precipitated substance in gas by inserting a pipe which is made of thermal nonconductive material and does not perfectly contact the wall of an exhaust flow passage, in the exhaust flow passage, in a vacuum pump in which the pressure at an exhaust port becomes nearly equal to the atmospheric pressure. CONSTITUTION:A rotary shaft 12 is rotatably supported in a housing 11 having a suction port 11A and exhaust port 11B by a bearing 21. A centrifugal compression pump stage 13 and a circumferential flow compression pump stage 14 are arranged on the rotary shaft 12 in the housing 11 ranging from the suction port 11A to the exhaust port 11B. Said rotary shaft 12 is driven by a motor 15 connected with the rotary shaft 12. In this vacuum pump, a pipe 11D made of the thermal nonconductive material such as quartz is inserted into an exhaust passage 11C. Therefore, the thermal transmission from gas to the insertion pipe 11D in the insertion pipe 11D can be reduced, and the cooling of gas in the insertion pipe 11D is prevented, and the clogging of the flow passage due to the precipitated substance generated by the cooling of gas can be prevented.
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