Fan assembly and fan hub cap

Abstract

An apparatus for a fan having an impeller with a hub and a plurality of blades extending from the hub includes a hub cap configured to mount to the hub of the impeller. The hub cap can include a plurality of slots corresponding to the blades of the impeller. The slots are sized to receive the blades when the hub cap is mounted to the hub, which shortens the working length of the blades.

What is claimed is: 
     
         1 . A fan assembly comprising:
 a fan having an impeller comprising a hub with a diameter and a plurality of blades extending radially from the hub, with a distance from the hub to a tip of the blade defining a working length of the blades; and   a hub cap configured to mount to the hub, comprising:
 an end wall having a diameter larger than the diameter of the hub; 
 a peripheral side wall extending from the end wall; and 
 a plurality of slots corresponding to the blades and formed in the side wall; 
   wherein the slots are sized to receive the blades, whereby, when the hub cap is mounted to the hub, the slots receive the blades to effectively shorten the working length of the blades.   
     
     
         2 . The fan assembly of  claim 1  wherein the fan further comprises a motor having an output shaft, wherein the impeller is mounted to the output shaft by a fastener. 
     
     
         3 . The fan assembly of  claim 2 , wherein the end wall of the hub cap comprises an opening which receives the fastener. 
     
     
         4 . The fan assembly of  claim 3 , wherein the end wall of the hub cap comprises a recess, and the opening is located in the recess. 
     
     
         5 . The fan assembly of  claim 1 , wherein the hub cap is mechanically fixed to the hub. 
     
     
         6 . The fan assembly of  claim 1 , wherein the hub cap is bonded to the hub. 
     
     
         7 . The fan assembly of  claim 1  wherein the fan further comprises a fan housing, wherein the impeller and the hub cap are located within the fan housing. 
     
     
         8 . The fan assembly of  claim 1 , wherein the plurality of blades extend radially from the hub to distal ends, and a distance between the peripheral side wall of the hub and the distal ends of the blades defines the working length of the blades. 
     
     
         9 . The fan assembly of  claim 1 , wherein the plurality of slots are angled to correspond to a pitch of the plurality of blades where the plurality of blades meet the peripheral side wall of the hub cap. 
     
     
         10 . The fan assembly of  claim 9 , wherein the plurality of blades extend radially from the hub to distal ends, and the pitch of the plurality of blades changes between the hub and the distal ends. 
     
     
         11 . The fan assembly of  claim 1 , wherein the peripheral side wall of the hub cap comprises a peripheral edge opposite the end wall, wherein the plurality of slots extend from the peripheral edge toward the end wall. 
     
     
         12 . The fan assembly of  claim 1 , wherein the hub of the impeller comprises an end wall having a diameter smaller than the diameter of the end wall of the hub cap, and a peripheral side wall extending from the end wall of the hub. 
     
     
         13 . The fan assembly of  claim 1 , wherein the peripheral side wall of the hub extends substantially parallel to the peripheral side wall of the hub cap.