| 摘要 |
PURPOSE:To prevent the increase of the driving torque by forming a plurality of relief holes which permit the communication between the operating space and the discharge side when the pressure in the operating space becomes over a prescribed discharge pressure, onto the fixed scroll member of a scroll type vacuum pump. CONSTITUTION:A plurality of communication ports 4 which communicate to an operating chamber 19 and a discharge side space 100 are formed onto the fixed scroll member 2 of a scroll type vacuum pump, and a check valve 16 which is opened when the pressure in the operating chamber 19 exceeds the discharge pressure is arranged at the opened part to the discharge side space 100 of the communication port 4. Therefore, even if the excessive compression is generated in the operating chamber 19 during the operation of the vacuum pump, the excessively compressed fluid is released into the discharge side space 100 by the discharge valve 16 safely, and the action of an excessive load onto a driving source because of the increase of the driving torque is prevented.
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