Patent attributes
A fan includes a hub and a blade assembly. The hub has a central portion and an extension portion. The extension portion is extended outwardly from a peripheral edge of the central portion. The blade assembly includes a plurality of blades. Each blade has a leading edge, each of the leading edges is an end point of each blade that is most close to the central portion. The blades are disposed around the hub. At least a part of the leading edges of the blades are connected to the extension portion, and distances between a center of the central portion and the leading edges of at least two blades are different. Therefore, the factors of fan and the quality of voice could be enhanced, and the multi-frequencies noise could be avoided during operation.
