Cooling fan

Abstract

A cooling fan has a structure to prevent objects from being stuck by the blades of the cooling fan. The cooling fan includes rings spaced from the hub of the cooling fan, that prevent objects from striking the blades while the fan turns. As an alternative, a fan includes ribs radially spaced on the fan blades so as to deflect objects before being struck by the blades.

What is claimed is:  
     
         1 . A cooling fan having a pressure side and a suction side, comprising: 
 a hub;    a plurality of blades extending radially outward from the hub; and    a first ring spaced from the hub and intersecting the plurality of blades, wherein a spacing between the hub and the first ring is less than about 12 mm.    
     
     
         2 . The cooling fan of  claim 1 , comprising: 
 a second ring spaced from the first ring and intersecting the plurality of blades, wherein a spacing between the first ring and the second ring is less than about 12 mm.    
     
     
         3 . The cooling fan of  claim 2 , wherein the first ring and the second ring extend outward from suction sides of the blades.  
     
     
         4 . The cooling fan of  claim 3 , wherein the first ring and the second ring extend outward at least about 1.5 mm from the suction sides of the blades.  
     
     
         5 . The cooling fan of  claim 4 , wherein the first ring is spaced from the hub a distance of between about 5 and 8 mm.  
     
     
         6 . The cooling fan of  claim 5 , wherein the second ring intersects the blades at tips of the blades.  
     
     
         7 . The cooling fan of  claim 6 , wherein the cooling fan is formed by molding.  
     
     
         8 . The cooling fan of  claim 2 , comprising: 
 a third ring spaced from the second ring and intersecting the plurality of blades, wherein the spacing between the second ring and the third ring is less than about 12 mm.    
     
     
         9 . The cooling fan of  claim 1 , wherein a pressure side of the first ring is connected to a suction side of the blades.  
     
     
         10 . The cooling fan of  claim 9 , wherein the first ring extends outward from suction sides of the blades at least about 1.5 mm from the suction sides of the blades.  
     
     
         11 . The cooling fan of  claim 1 , wherein the first ring extends outward from suction sides of the blades at least about 1.5 mm from the suction sides of the blades.  
     
     
         12 . The cooling fan of  claim 11 , wherein the first ring is spaced from the hub a distance of between about 5 and 8 mm.  
     
     
         13 . The cooling fan of  claim 1 , wherein tips of the blades are free.  
     
     
         14 . A cooling fan having a pressure side and a suction side, comprising: 
 a hub; and    a plurality of blades extending outward from the hub, at least one blade including: 
 a first rib spaced from the hub and extending outward from a suction side of the blade, wherein the spacing between the hub and the first rib is less than about 12 mm; and  
 a second rib spaced from the first rib and extending outwardly from a suction side of the blade, wherein the spacing between the first rib and the second rib is less than about 12 mm.  
   
     
     
         15 . The cooling fan of  claim 14 , wherein the first and second ribs each include a raised portion extending outward from a suction side of the at least one blade.  
     
     
         16 . The cooling fan of  claim 15 , wherein the raised portions extend at least about 1.5 mm above the suction side of the at least one blade.  
     
     
         17 . The cooling fan of  claim 16 , wherein the first rib is spaced from the hub a distance of between about 5 and 8 mm.  
     
     
         18 . The cooling fan of  claim 17 , wherein the at least one blade comprises at least half of the plurality of blades.  
     
     
         19 . The cooling fan of  claim 14 , wherein the first and second ribs extend substantially along a circumferential direction of the cooling fan.  
     
     
         20 . The cooling fan of  claim 14 , wherein the cooling fan is formed by molding process.