| 摘要 |
PROBLEM TO BE SOLVED: To provide a screw groove type vacuum pump capable of discharging air at a high speed over from a low vacuum area to a high vacuum area and having excellent durability. SOLUTION: Each screw element 4 (n) formed in the peripheral surface 30 of a rotor 3 for screw groove type vacuum pump is provided with a rotor blade type pump element part 41 formed into the geometric shape on the basis of the design theory of a turbo-molecular pump, and a transiting screw element part 42 and a screw groove type pump element 43 are continuously formed to the pump element 41. Since the rotor blade type pump element 41 is provided, opening area of a suction port is increased, and the discharging speed in a high-vacuum area can be increased while maintaining the compressive performance. Since the rotor blade type pump element 41 has the structure remarkably more simple than that of a conventional blade part formed by combining a rotor blade and a stator blade, lowering of durability due to the deposition of the reactive gas or the like can be avoided.
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