Patent ID: 7654792

Claim:
A blower comprising: a plurality of housings including at least an upper housing and a lower housing, each of the housings having a plurality of blades arranged about an axis; wherein the upper housing includes a flat lower surface and a lower twist-locking portion, and the lower housing includes a flat upper surface and an upper twist-locking portion; when the flat lower surface engages the flat upper surface, and the lower housing is turned about a center axis by a rotational angle with respect to the upper housing, the lower twist-locking portion frictionally engages the upper twist-locking portion so as to restrict movement of the upper housing with respect to the lower housing in axial and circumferential directions; and each of the lower twist-locking portion and the upper twist-locking portion is arranged along at least one outermost edge of a corner of the upper housing and the lower housing, respectively, such that when the lower twist-locking portion engages the upper twist-locking portion in the circumferential direction each of the outermost edge of the lower twist-locking portion and the outermost edge of the upper twist-locking portion define a portion of a continuous contour in the circumferential direction.