| 摘要 |
PROBLEM TO BE SOLVED: To provide a compact dry turbo vacuum pump of small parts number and easy manufacture and control for reducing a cost and dispersion of the performance caused by manufacturing factors. SOLUTION: At least a first stage impeller of a circumferential flow pump 4b and that of a centrifugal pump 4a are integrated with each other, ribs are provided on a stator 2 and a motor casing 10, and communication passages 22, 22a, 25, 26a, 26b, 27a and 27b for lubricating oil and cooling oil are formed inside the ribs. In addition, the shape of a surface facing an impeller of a stage-to-stage wall of the stator 2 is flat, and manufactured by a regular casting. COPYRIGHT: (C)2004,JPO
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