| 摘要 |
PROBLEM TO BE SOLVED: To certainly prevent a lubricant in a gear box chamber from flowing out to an exhaust chamber with a simple structure without making a size of a volume type vacuum pump large. SOLUTION: In the volume type vacuum pump, a driving part exists and a driving shaft is penetrated through the gear box chamber and the exhaust chamber. An oil molecule intrusion route from the gear box chamber to the exhaust chamber is constituted to a complex route comprising a single or a plurality of non-contact type shaft seals. An effect for pushing back the oil is obtained by flowing an inert gas to a direction contrary to the intrusion route of the oil molecule into the complex route. The flowing out of the lubricant to the exhaust chamber can be certainly prevented by disposing a contact type shaft seal in a predetermined direction even if the inert gas does not flow at the time of stopping of the volume type vacuum pump. A shaft seam mechanism is constituted by disposing an exhaust hole for forcedly suctioning the inside of the gear box, a bearing oil pouring hole and a single or a plurality of non-contact type shaft seals for controlling a flowing amount of the inert gas into the exhaust chamber and enhancing the pressure between piston rings to which the inert gas flows. COPYRIGHT: (C)2003,JPO
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