| 摘要 |
PROBLEM TO BE SOLVED: To reduce noise emission and enhance air blowing efficiency. SOLUTION: A peripheral edge 3 of a hub 2 is composed of a front edge portion 4 formed non-circular in rotational symmetry and a rear edge portion 5 formed circular, and a vane 1 is installed in eccentricity toward the side of hub rotation at the boundary between the two edge portions 4 and 5 and in the part of a long arc-shaped peripheral edge 6 where the curvature between two adjoining projecting ends 2A of the front edge portion 4 is small.
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