Patent ID: 7163371
Filing Date: 2007-01-16
Classification: F04D

Abstract:
1. A centrifugal fan that takes in gas from a rotational axis direction and blows the gas out in a direction that intersects the rotational axis, comprising: an impeller that rotates about the rotational axis; and a bell mouth having an inlet arranged so that it opposes said impeller, and a recessed part that forms a recessed negative pressure space around said inlet facing the impeller side, and that guides the inlet gas to said impeller, said bell mouth further having a flat part that extends on the outer circumferential side of said recessed part in the radial direction in a direction that intersects the rotational axis, and a curved part that extends on the inner circumferential side in the radial direction of said recessed part toward the impeller side, and that forms said inlet, the portion of said recessed part that is most recessed on the impeller side being positioned on the impeller side of a connecting portion between said flat part and said recessed part, and being positioned on the impeller side of a connecting portion between said curved part and said recessed part, the rotational axis to the connecting portion between said flat part and said recessed part defining a first length with a length ratio of the first length to an outer radius of said impeller being greater than or equal to 0.8 and less than 1.4.