| 摘要 |
PROBLEM TO BE SOLVED: To reduce leakage from a compression apace having high pressure in the vicinity a center part to a compression space having low pressure by gradually reducing at least the blade thickness of fixing spiral blade or a swirling spiral blade from a constant position to a winding end. SOLUTION: In a swirling spiral blade 3, its impeller thickness is gradually reduced from a prescribed position 11 faced from a winding start to a winding end, to the winding end. In the case where the swirl spiral blade 3 and a fixed spiral blade 4 are assembled, a frequency when a seal part 12 of a side surface of the fixed spiral blade 4 disposed in the vicinity of a center part and a side surface of the swirling spiral blade 3 is brought into contact with a seal part 13 of a side surface of the fixed spiral blade 4 disposed in the vicinity of an outside and a side surface of this swirling spiral blade 3, is improved, sealing performance is improved, leakage is reduced in the vicinity of a center part having a large pressure difference between adjacent compression spaces, and a compression efficiency is also improved. Since a pressure difference between adjacent compression spaces in the vicinity of the outside is small, leakage can be suppressed even if a clearance of the seal part 13 is wide.
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