| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem of causing a lowering of exhaust efficiency of a pump due to the rise of valve opening pressure caused by the increase of hardness of a valve element at the drop of temperature in a check valve on the exhaust side of a vacuum pump structured to open the valve by elastically deforming the plate-like valve element with exhaust pressure to separate it from a seat face. SOLUTION: A clearance g is provided between the valve element 21 and a stopper face 23a of a valve element holder 23 receiving the base end part of the valve element, and the valve element 21 is liftable in a thickness direction within a range of the clearance g without being deformed. With this lift, the valve element 21 is separated from the seat face 22 before the valve element is elastically deformed with exhaust pressure. The check valve 20 is thereby opened, and the valve opening pressure of the check valve is reduced to the negligible degree. COPYRIGHT: (C)2004,JPO
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