Fan construction

Claim 1

A fan construction comprising an open-ended outer cylinder having inlet and outlet ends, an open-ended inner cylinder fixedly mounted in spaced relation axially within said outer cylinder spaced from the inlet end thereof a generally conoidal hub having a maximum diameter approximately equal to that of said inner cylinder and journaled axially within said outer cylinder adjacent to said inner cylinder and tapering toward said inlet enD, a plurality of air-foiled blades carried by said hub for rotation therewith and each extending along the hub surface at an angle oblique to the hub axis and direction of hub rotation, a conical shroud circumposed spacedly about said hub proximate to the extremities of said blades for rotation therewith and combining with said hub to define an annular passageway of increasing diameter in the direction from said inlet end to the space between said cylinders, said blades serving to move air in said inlet end through said annular passageway and into the annular space between said cylinders, guide vanes in said annular space each extending arcuately away from said passageway and thence tangentially in substantial parallelism with the axis of said cylinders, and an inlet cone fixed in the inlet end of said outer cylinder and tapering inwardly toward said shroud, said inlet cone terminating at its inner end within said shroud, for conducting air to said passageway with minimum leakage between said cone and passageway.