| 摘要 |
PROBLEM TO BE SOLVED: To provide a hybrid type, that is, combined type vacuum pump especially a non-lubricated (dry) type vacuum pump provided with two or more different parts with different operating methods capable of improving an operating range of a pressure and a flow rate. SOLUTION: This combined vacuum mump 1 comprises a pump body 6 divided into an upper chamber 40 and a lower chamber 42 by a partition 12. The lower chamber 42 is occupied by a screw pump part 2 and the upper chamber 40 is occupied by a Roots pump part 4. The Roots pump part 4 has two rotors 32 respectively having a disc 34 capable of rotating by a bore 36 of the partition 12.
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