Cooling fan

Abstract

A cooling fan includes a frame ( 100 ) and an impeller ( 200 ) with blades ( 240 ) disposed in the frame ( 100 ). The frame ( 100 ) has a base ( 140 ) and a sidewall ( 160 ) extending from a periphery of the base ( 140 ) with an air outlet ( 180 ) defined therein. The base ( 140 ) has an air inlet ( 142 ) and a vent hole ( 148 ) defined therein. The vent hole ( 148 ) is near the air outlet ( 180 ) and between tip portions of the blades ( 240 ) and the sidewall ( 160 ). In a preferred embodiment, the base ( 140 ) has a supporting portion ( 144 ) disposed in the air inlet ( 142 ). Two ribs ( 146 ) extend from a periphery of the supporting portion ( 144 ) towards the base ( 140 ). One of the ribs ( 146 ) is arranged adjacent to the air outlet ( 180 ) and has a changeable width which is gradually increased along a direction from the supporting portion ( 144 ) to the base ( 140 ).

1 . A cooling fan comprising:
 a frame having a base and a sidewall extending from a periphery of the base with an air outlet defined therein, the base having an air inlet and a vent hole defined therein;   an impeller having a plurality of blades disposed in the frame;   wherein the vent hole is in vicinity of the air outlet and between tip portions of the blades and the sidewall of the frame.   
   
   
       2 . The cooling fan as described in  claim 1 , wherein the sidewall has a curved tongue portion formed thereon and the vent hole is in vicinity of the curved tongue portion. 
   
   
       3 . The cooling fan as described in  claim 2 , wherein the curved tongue portion protrudes inwardly from the sidewall and in vicinity of the air outlet. 
   
   
       4 . The cooling fan as described in  claim 1 , wherein the base further comprises a supporting portion disposed in the air inlet for supporting the impeller and two ribs extending from a periphery of the supporting portion towards the base so as to connect the supporting portion with the base; wherein one of the ribs is arranged adjacent to the air outlet. 
   
   
       5 . The cooling fan as described in  claim 4 , wherein the sidewall has a curved tongue portion formed thereon and the vent hole is in vicinity of the curved tongue portion; the curved tongue portion protrudes inwardly from the sidewall and in vicinity of the air outlet; the one of the ribs arranged adjacent to the air outlet is in vicinity of the curved tongue portion. 
   
   
       6 . The cooling fan as described in  claim 5 , wherein the one of the ribs arranged adjacent to the air outlet has a changeable width which is gradually increased along a direction from the supporting portion to the curved tongue portion. 
   
   
       7 . The cooling fan as described in  claim 5 , wherein the vent hole is positioned between the one of the ribs arranged adjacent to the air outlet and the curved tongue portion. 
   
   
       8 . A cooling fan comprising:
 a frame having a base and a sidewall extending from a periphery of the base with an air outlet defined therein, wherein the base has an air inlet defined therein, a supporting portion disposed in the air inlet and two ribs extend from a periphery of the supporting portion towards the base so as to connect the supporting portion with the base; wherein one of the ribs is arranged adjacent to the air outlet and has a changeable width which is gradually increased along a direction from the supporting portion to the base; and   an impeller having a plurality of blades disposed in the frame supported on the supporting portion.   
   
   
       9 . The cooling fan as described in  claim 8 , wherein the sidewall has a curved tongue portion formed thereon and the one of the ribs arranged adjacent to the air outlet is in vicinity of the curved tongue portion. 
   
   
       10 . The cooling fan as described in  claim 9 , wherein the curved tongue portion protrudes inwardly from the sidewall and is disposed in vicinity of the air outlet. 
   
   
       11 . The cooling fan as described in  claim 10 , wherein the base further comprises a vent hole defined therein, the vent hole being disposed in vicinity of the curved tongue portion. 
   
   
       12 . The cooling fan as described in  claim 11 , wherein the vent hole is positioned between the one of the ribs arranged adjacent to the air outlet and the curved tongue portion.