Fan assembly

Abstract

A fan assembly that includes a housing having an inner peripheral wall defining a flow through opening, a stator located within the through opening and comprising an annular array of stationary blades provided along the inner peripheral wall, a rotor comprising a hub having a front wall supporting an outer peripheral wall having a forward balancing ring and an aft balancing ring, and an annular array of non-stationary blades extending from the outer peripheral wall, and strengthening ribs.

What is claimed is: 
     
         1 . A fan assembly comprising:
 a housing having an inner peripheral wall defining a flow through opening;   a stator located within the through opening and comprising an annular array of stationary blades provided along the inner peripheral wall;   a rotor comprising a hub having a front wall supporting an outer peripheral wall having a forward balancing ring and an aft balancing ring, and an annular array of non-stationary blades extending from the outer peripheral wall; and   wherein the hub is made of cast metal with a plurality of strengthening ribs located between the forward balancing ring and the aft balancing ring.   
     
     
         2 . The fan assembly of  claim 1  wherein the strengthening ribs extend between the forward balancing ring and the aft balancing ring. 
     
     
         3 . The fan assembly of  claim 2  wherein the strengthening ribs extend in a direction generally parallel to an axis of rotation of the rotor. 
     
     
         4 . The fan assembly of  claim 3  wherein the strengthening ribs reduce in cross sectional area in a direction from the forward balancing ring to the aft balancing ring. 
     
     
         5 . The fan assembly of  claim 4  wherein the strengthening ribs continuously reduce in cross sectional area. 
     
     
         6 . The fan assembly of  claim 5  wherein the front wall comprises a collar, with the front wall extending between the collar and the outer peripheral wall, and the front wall having a convex cross section between the collar and the outer peripheral wall. 
     
     
         7 . The fan assembly of  claim 1  wherein the strengthening ribs extend in a direction generally parallel to an axis of rotation of the rotor. 
     
     
         8 . The fan assembly of  claim 1  wherein the strengthening ribs reduce in cross sectional area in a direction from the forward balancing ring to the aft balancing ring. 
     
     
         9 . The fan assembly of  claim 8  wherein the strengthening ribs continuously reduce in cross sectional area. 
     
     
         10 . The fan assembly of  claim 1  wherein the front wall comprises a collar, with the front wall extending between the collar and the outer peripheral wall, and the front wall having a convex cross section between the collar and the outer peripheral wall. 
     
     
         11 . The fan assembly of  claim 1  wherein the strengthening ribs are sized and located to reduce hoop stress in the outer peripheral wall. 
     
     
         12 . The fan assembly of  claim 11  wherein the reduction of the hoop stress is at least 20% than a stator without the strengthening ribs at a predetermined rotational speed. 
     
     
         13 . The fan assembly of  claim 12  wherein the reduction of the hoop stress is at least 30%. 
     
     
         14 . The fan assembly of  claim 13  wherein the predetermined rotational speed is at least 7,000 rpm. 
     
     
         15 . The fan assembly of  claim 14  wherein the predetermined rotational speed is at least 8,000 rpm. 
     
     
         16 . The fan assembly of  claim 15  wherein the stator has a diameter of at least 14 inches. 
     
     
         17 . The fan assembly of  claim 16  wherein the stator has a diameter of at least 16 inches. 
     
     
         18 . The fan assembly of  claim 1  wherein the strengthening ribs maintain a constant cross sectional area in a direction from the forward balancing ring to the aft balancing ring.