| 摘要 |
PROBLEM TO BE SOLVED: To provide a multiblade impeller which can realize calmness by a centrifugal fan, especially by a small centrifugal fan. SOLUTION: In a centrifugal fan in which the outside diametral dimension of a multiblade impeller 3 mounted in is set to 250mm or below, and the number of blades is 50 or more, a ratio of the inlet side inner circumferential diameter of the multiblade impeller 3 to the outlet side peripheral diameter thereof is set in a range of from 0.4 to 0.75, an outlet angleβ2 is set to 100 or more and an inlet angleβ1 is set in a range of from 30 deg. to 85 deg., and also a circular arc surface whose size is more than 1/4 of the thickness of a blade 4 is formed at the corner of the inlet side inner circumferential surface of the blade 4, and the surface shape of the outlet side peripheral end 4-2 of the blade 4 forms an acute angled shape or a minute circular arc at an end by being thinned according as it approaches a peripheral end 4-1, and also both or one surface shape of front and rear surfaces is formed into a streamline shape.
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