Cooling fan with internally tapered housing

Abstract

A cooling fan includes a fan housing and a rotor. The fan housing includes an inner surface defining an inner space therein. The inner surface expands along a direction parallel to a central axis of the fan housing. The rotor is received in the inner space and surrounded by the inner surface of the fan housing. The rotor includes a hub and a plurality of rotary blades extending outwardly from the hub. Each of the rotary blades has an outer edge confronting the inner surface of the fan housing. The outer edge of each rotary blade slants towards the central axis of the fan housing.

1 . A cooling fan comprising:
 a rotor comprising a hub and a plurality of rotary blades extending outwardly from the hub; and   a fan housing surrounding the rotor, the fan housing having an inner surface confronting the rotor, the inner surface expanding along a direction parallel to a central axis of the fan housing.   
     
     
         2 . The cooling fan of  claim 1 , wherein an angle defined between the inner surface of the fan housing and the central axis of the fan housing is in the range of 0.3˜3 degrees. 
     
     
         3 . The cooling fan of  claim 1 , wherein each of the rotary blades comprises an outer edge confronting the inner surface of the fan housing, the outer edge of each rotary blade aslant towards the central axis of the fan housing. 
     
     
         4 . The cooling fan of  claim 3 , wherein an angle defined between the outer edge of each rotary blade and the central axis of the fan housing is in the range of 0.3˜3 degrees. 
     
     
         5 . The cooling fan of  claim 3 , wherein the outer edge of each rotary blade is parallel to the inner surface of the fan housing. 
     
     
         6 . The cooling fan of  claim 1 , wherein the fan housing defines an air inlet and an air outlet at opposite sides, the air inlet being larger than the air outlet. 
     
     
         7 . The cooling fan of  claim 6 , wherein the inner surface of the fan housing expands from the air outlet towards the air inlet. 
     
     
         8 . The cooling fan of  claim 7 , wherein each of the rotary blades comprises an outer edge confronting the inner surface of the fan housing, a first end of the outer edge adjacent to the air outlet being closer to the central axis of the fan housing relative to a second end of the outer edge adjacent to the air inlet. 
     
     
         9 . The cooling fan of  claim 7 , wherein each of the rotary blades comprises an outer edge confronting the inner surface of the fan housing, the outer edge of each rotary blade parallel to the inner surface of the fan housing. 
     
     
         10 . The cooling fan of  claim 9 , wherein an angle defined between the inner surface of the fan housing and the central axis of the fan housing is in the range of 0.3˜3 degrees. 
     
     
         11 . The cooling fan of  claim 7 , wherein an angle defined between the inner surface of the fan housing and the central axis of the fan housing is in the range of 0.3˜3 degrees. 
     
     
         12 . A cooling fan comprising:
 a fan housing having an inner surface defining an inner space therein, the inner surface expanding along a direction parallel to a central axis of the fan housing; and   a rotor received in the inner space and surround by the inner surface of the fan housing, the rotor comprising a hub and a plurality of rotary blades extending outwardly from the hub, each of the rotary blades having an outer edge confronting the inner surface of the fan housing, the outer edge of each rotary blade aslant towards the central axis of the fan housing.   
     
     
         13 . The cooling fan of  claim 12 , wherein an angle defined between the inner surface of the fan housing and the central axis of the fan housing is in the range of 0.3˜3 degrees. 
     
     
         14 . The cooling fan of  claim 12 , wherein an angle defined between the outer edge of each rotary blade and the central axis of the fan housing is in the range of 0.3˜3 degrees. 
     
     
         15 . The cooling fan of  claim 12 , wherein the outer edge of each rotary blade is parallel to the inner surface of the fan housing. 
     
     
         16 . The cooling fan of  claim 15 , wherein an angle defined between the inner surface of the fan housing and the central axis of the fan housing is in the range of 0.3˜3 degrees.