| 摘要 |
PROBLEM TO BE SOLVED: To reduce noise and reduce pressure pulsation by a constitution of relatively low cost. SOLUTION: A casing 10 of a Roots blower 1 comprises: an approximately cylindrical barrel part 13 and a bearing case 14 and a bearing plate which seal both ends of the barrel part 13. Curved grooves 30 of circular arc shape concentric with respective rotation shafts 23 of rotors 21 and 22 are arranged on inner surfaces of the bearing case 14 and the bearing plate. The grooves 30 respectively make a compression chamber R4 at a supply opening 18 side communicate with compression chambers R2 and R3 at a rear side of the compression chamber R4 in a travelling direction. The barrel part 13, the bearing case 14, and the bearing plate are constituted by casting, and are assembled. COPYRIGHT: (C)2004,JPO&NCIPI
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