Impeller and cooling fan using the same

Abstract

A cooling fan ( 10 ) includes a bottom housing ( 12 ), a top cover ( 14 ) covering the bottom housing, and impeller ( 16 ) and stator accommodated in a space formed between the bottom housing and the top cover. The impeller includes a hub ( 162 ), and a plurality of blades ( 164 ) radially and outwardly extending from the hub. Each of the blades includes a windward surface ( 164 a ) and a leeward surface ( 164 b ) which has a different configuration with the windward surface. The windward surface has a tip portion selected from a group consisting of forward curved surface and planar surface. The leeward surface has a tip portion selected from a group consisting of planar surface and backward curved surface.

1 . An impeller comprising:
 a hub; and   a plurality of blades radially extending from the hub, each of the blades comprising a windward surface and a leeward surface which has a different configuration from the windward surface, the windward surface having a tip portion selected from a group consisting of forward curved surface and planar surface, the leeward surface having a tip portion selected from a group consisting of planar surface and backward curved surface.   
   
   
       2 . The impeller of  claim 1 , wherein the tip portion of the windward surface is a forward curved surface, and the tip portion of the leeward surface is a backward curved surface. 
   
   
       3 . The impeller of  claim 1 , wherein the tip portion of the windward surface is a planar surface, and the tip portion of the leeward surface is a backward curved surface. 
   
   
       4 . The impeller of  claim 1 , wherein the tip portion of the windward surface is a forward curved surface, and the tip portion of the leeward surface is a planar surface. 
   
   
       5 . A cooling fan comprising:
 a bottom housing;   a top cover covering the bottom housing; and   impeller and stator accommodated in a space formed between the bottom housing and the top cover, the impeller comprising:   a hub; and   a plurality of blades radially extending from the hub, each of the blades comprising a windward surface and a leeward surface which has a different configuration from the windward surface, the windward surface having a tip portion selected from a group consisting of forward curved surface and planar surface, the leeward surface having a tip portion selected from a group consisting of planar surface and backward curved surface.   
   
   
       6 . The cooling fan of  claim 1 , wherein the tip portion of the windward surface is a forward curved surface, and the tip portion of the leeward surface is a backward curved surface. 
   
   
       7 . The cooling fan of  claim 1 , wherein the tip portion of the windward surface is a planar surface, and the tip portion of the leeward surface is a backward curved surface. 
   
   
       8 . The cooling fan of  claim 1 , wherein the tip portion of the windward surface is a forward curved surface, and the tip portion of the leeward surface is a planar surface.