| 摘要 |
PURPOSE:To largely shorten the time required for exhausting by arranging a passage opening/closing means at the outlet side of blowing means, and connecting an exhaust pump between the opening/closing means and the outlet. CONSTITUTION:A radiator 22 and a normal-open solenoid switching valve 23 are arranged at the positions of a main tube 10A under a Root's blower 11, and a pump 19 is connected through a cock valve 21 between the radiator 22 and the valve 23. A normal-close type solenoid switching valve 24 is connected in parallel with the valve 21. When a switch 25 is set to exhaust mode, the valve 23 is closed, the valve 24 is opened, and the blower 11 and the pump 19 are rotatably driven. Thus, since gas discharged from the blower 11 is supplied to the pump 19 so that the blower 11 operates as a front-stage pump, exhausting speed is remarkably improved to significantly shorten the exhausting time.
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