Patent ID: 7264446

Claim:
A centrifugal-fan impeller comprising: a plurality of vanes each parallel to a center axis and arrayed encompassing the center axis so that the vane outer radius 2 r is no more than 25 mm and so as to be spaced apart at a predetermined pitch, said vanes being of less than 0.7 mm maximum thickness, and of length fL satisfying 2≦fL/r≦20 and exceeding 40 times said maximum thickness; and an approximately round cylindrical reinforcing ring linking one end of said plurality of vanes, said reinforcing ring having a diametrical thickness of from ½ to 3 times said maximum thickness of each of said plurality of vanes, and as measured along the center axis, having a length at least 2 times the pitch of said plurality of vanes; wherein said plurality of vanes and said reinforcing ring linking the vanes at one end are formed unitarily by injection molding; and the thickness of each of said plurality of vanes in the region where each is connected to said reinforcing ring is said maximum thickness.