Patent ID: 8157524

Claim:
An axial flow fan comprising: a hub rotatable about a central axis, the hub including a front face and a cylindrical portion; a plurality of blades extending radially outwardly from the cylindrical portion of the hub; an aperture through the front face of the hub, the aperture at least partially defined by a first surface oriented non-parallel with the front face; a first lip positioned on the hub on only an interior surface of the front face, the first lip having a second surface adjacent the first surface that at least partially overlaps the aperture and provides a tortuous passageway through the aperture; and a rib extending radially along the interior surface of the front face of the hub; wherein the aperture includes a radially-extending, first portion and a second portion extending substantially laterally from the first portion, and wherein the second surface of the first lip at least partially overlaps the second portion of the aperture; wherein the rib is aligned with the radially-extending, first portion of the aperture; and wherein the aperture includes a third portion radially spaced from the second portion and extending substantially laterally from the first portion, wherein the third portion of the aperture is at least partially defined by a third surface oriented non-parallel with the front face, and wherein the axial flow fan further includes a second lip having a fourth surface adjacent the third surface that at least partially overlaps the third portion of the aperture and provides a tortuous passageway through the third portion of the aperture.