Patent ID: 7334986

Claim:
A centrifugal fan, comprising: an impeller; and a housing having a curved portion with a radius of curvature, defined as a distance between a rotational axis of the impeller and the housing, wherein the radius of curvature decreases, in a direction of rotation of the impeller, from a first end of the curved portion of the housing to a single point where the radius of curvature is a minimum, the radius of curvature increases, in the direction of rotation of the impeller, from the point where the radius of curvature is the minimum to a second end of the curved portion of the housing, a gap exists between an outer circumference of the impeller and the housing at the point where the radius of curvature is a minimum, a cutoff portion is formed at the first end of the curved portion of the housing, and the point where the radius of curvature is a minimum is located approximately 170° to 190° from the second end of the curved portion of the housing.