Adjustable impeller for axial flow fan

Abstract

A fan assembly has a plurality of blades received on a rotatable hub and held on the hub with a retainment mechanism. The hub has a plurality of hub stations located thereon, each hub station having a plurality of radially extending hub cogs and a hub indexing mark. Each blade in the fan assembly has a blade end having a plurality of radially extending blade cogs configured to interface with the hub cogs. The blade end also has a blade positioning mark adjacent one of the blade cogs. The blade may be rotated with respect to the hub to a plurality of different orientations and still have the blade cogs mesh with the hub cogs.

What is claimed is: 
     
         1 . A fan assembly having an impeller with a plurality of blades configured to move air as the impeller is rotated each blade is received on a rotatable hub and held on the hub with a retainment mechanism, wherein the hub has an outward surface with a plurality of hub stations located thereon, each hub station having a plurality of radially extending hub cogs, and a hub indexing mark located adjacent one of the hub cogs, wherein each blade has a blade end having a plurality of radially extending blade cogs configured to interface with the hub cogs and a blade positioning mark adjacent one of the blade cogs, the blade cogs and hub cogs configured so that when the blade is brought into position such that the blade end mates with one of the plurality of hub stations, the hub cogs mesh with the blade cogs, and wherein the blade may be rotated with respect to the hub to a plurality of different orientations and still have the blade cogs mesh with the hub cogs. 
     
     
         2 . The fan assembly of  claim 1  wherein the retainment mechanism includes a front cover and a rear cover held together with a plurality of bolts and nuts that mechanically secure the blades on the hub. 
     
     
         3 . The fan assembly of  claim 1  wherein the hub has at least one hub station for each of the blades on the fan assembly. 
     
     
         4 . The fan assembly of  claim 1  when the blade is brought against the hub with the blade positioning mark aligned with the hub indexing mark, the blade has a blade pitch angle that is a benchmark blade angle. 
     
     
         5 . The fan assembly of  claim 4  wherein the blade can be rotated with respect to the hub in a first direction to decrease the blade angle of the blade relative to the benchmark blade angle, and the blade can be rotated with respect to the hub in a second direction opposite the first direction to increase the blade angle of the blade relative the benchmark blade angle such that the blade angle of the blade can be selected or changed by the operator to any one of a plurality of different blade angles