Cooling fan

Abstract

A cooling fan includes a frame ( 100 ) and an impeller ( 200 ) having a plurality of blades ( 240 ) disposed in the frame ( 100 ). The frame ( 100 ) has a cap ( 120 ) with an air inlet ( 122 ), a base ( 140 ) and a sidewall ( 160 ) extending from a periphery of the base ( 140 ) with an air outlet ( 180 ) defined therein. The cap ( 120 ) is mounted on the sidewall ( 160 ) with a chamber formed between the cap ( 120 ), the base ( 140 ) and the sidewall ( 160 ). A curved tongue portion ( 190 ) is formed on the sidewall ( 160 ) in vicinity of the air outlet ( 180 ). A protrusion ( 124 ) is formed on the cap ( 120 ) in vicinity of the curved tongue portion ( 190 ) and protrudes into the air inlet ( 122 ).

1 . A cooling fan comprising:
 an impeller having a plurality of blades; and   a frame having a cap with an air inlet, a base and a sidewall extending from a periphery of the base with an air outlet defined therein; wherein the cap is mounted on the sidewall with a chamber formed between the cap, the base and the sidewall, and the impeller is disposed in the chamber;   wherein a curved tongue portion is formed on the sidewall in vicinity of the air outlet and protrudes into the chamber; and   wherein a protrusion is formed on the cap in vicinity of the curved tongue portion and protrudes into the air inlet.   
   
   
       2 . The cooling fan as described in  claim 1 , wherein a vent hole is defined in the base in vicinity of the curved tongue portion. 
   
   
       3 . The cooling fan as described in  claim 2 , wherein the protrusion faces the vent hole. 
   
   
       4 . The cooling fan as described in  claim 2 , wherein the vent hole is positioned between tips of the blades and the sidewall. 
   
   
       5 . The cooling fan as described in  claim 4 , wherein the base has an air inlet defined therein, and another protrusion is formed on the base and protrudes into the air inlet of the base; the vent hole is positioned between the another protrusion and the curved tongue portion. 
   
   
       6 . The cooling fan as described in  claim 1 , wherein the base has an air inlet defined therein, and another protrusion is formed on the base and protrudes into the air inlet of the base. 
   
   
       7 . The cooling fan as described in  claim 6 , wherein the protrusion and the another protrusion are aligned with each other. 
   
   
       8 . A cooling fan comprising:
 a frame comprising a chamber, an air inlet and an air outlet communicated with the chamber, a protrusion formed on the frame and protruded into the air inlet; and   an impeller having a plurality of blades disposed in the chamber.   
   
   
       9 . The cooling fan as described in  claim 8 , wherein another protrusion is formed on the frame and protrudes into another air inlet defined in the frame. 
   
   
       10 . The cooling fan as described in  claim 9 , wherein the protrusion and the another protrusion are aligned with each other. 
   
   
       11 . The cooling fan as described in  claim 8 , wherein the frame comprises a cap, a base and a sidewall extending from a periphery of the base, and the cap is mounted on the sidewall so that the chamber is formed between the cap, the base and the sidewall; the air inlet is defined in the cap, and the air outlet is defined in the sidewall. 
   
   
       12 . The cooling fan as described in  claim 11 , wherein a curved tongue portion is formed on the sidewall in vicinity of the air outlet. 
   
   
       13 . The cooling fan as described in  claim 12 , wherein the protrusion is in vicinity of the curved tongue portion. 
   
   
       14 . The cooling fan as described in  claim 12 , wherein the protrusion is away from the curved tongue portion.