| 摘要 |
An impeller includes a substantially cylindrical cup portion arranged to rotate about a center axis, a plurality of blades fixed to an outer circumferential surface of the cup portion for unitary rotation with the cup portion to draw air from one axial side and discharge the air to the other axial side, and an annular connector portion arranged to interconnect the blades. The connector portion has a substantially cylindrical shape in a position spaced apart about 70% to about 90% of the radial length of the blades from the base of each of the blades on the outer circumferential surface of the cup portion, and the ratio of a total axial height of the connector portion to a total radial gap between the outer circumferential surface of the cup portion and the inner circumferential surface of the connector portion is equal to or smaller than about 0.9.
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