Patent ID: 8133022

Claim:
A frame for an axial fan comprising: a housing arranged to accommodate an impeller; a base section disposed on an inside of the housing; and supporting ribs extending from the base section to the housing to support the base section, the supporting ribs being disposed on the inside of the housing; wherein in a connecting region between each of the supporting ribs and the base section: a first corner portion and a second corner portion are arranged on an upstream side and on a downstream side of a rotational direction of the impeller, respectively; and a curvature radius of the first corner portion is different from a curvature radius of the second corner portion; and each and every one of the supporting ribs inside of the housing has substantially the same shape and substantially the same dimensions such that all of the first corner portions have substantially identical curvature radii and all of the second corner portions have substantially identical curvature radii.