Patent ID: 7484925

Claim:
A rotary axial fan for moving air through a heat exchanger for an internal combustion engine cooling system, comprising: a hub extending annularly about a central axis of rotation having a mounting surface enabling the hub to be attached to and rotated by a drive member; a plurality of elongate spaced apart primary fan blades each having a base attached to the hub and radially extending outward therefrom; an annular shroud attached to the plurality of primary fan blades and supported coaxially with the central axis, the annular shroud having a generally circumferential wall portion spaced radially from the hub to limit radial flow of air along the primary fan blades, wherein the annular shroud attaches to the plurality of primary fan blades at a radial distance less than the overall radial length of the primary fan blades and each primary fan blade is further defined by a first primary fan blade segment oriented between the shroud and the hub, and a second primary fan blade segment oriented externally from the shroud; a plurality of secondary fan blades interposed between the primary fan blades each having a first end attached to the annular shroud and a blade section projecting therefrom and terminating in a second end that is not attached to the hub; and a stationary external shroud provided about the second primary fan blade segments to limit the air to travel in an axial direction, proximate to a free tip of the second primary fan blade segments.