| 摘要 |
PURPOSE:To achieve high vacuum condition with one stage pump by forming a region in which both ends of an operating chamber is closed by the meshing of rotors in a screw type vacuum pump. CONSTITUTION:An operating chamber 65 is filled with gas sucked from an intake port 63 as a rotor is rotated. Further, as the rotor is rotated, the gas charged in operating chambers 67, 70 moves axially with a constant volume since both ends of the operating chamber are sealed with meshing portions 68, 72 of the rotor. When ends of operating chambers 72, 73 contact a discharge side end plate 10, the volume of the gas begins to decrease and soon is discharged from a discharge port. Since two portions between the intake port 63 and discharge port are enclosed by the meshing of the rotors, the gas can be compressed with high compression ratio irrespective of the intake side pressure.
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