Centrifugal fan

Abstract

A centrifugal fan is described. The centrifugal fan is suitable for a portable electrical apparatus. A tongue shape is formed from a volute sidewall of a casing of the centrifugal fan. The volute sidewall is formed with at least one groove substantially extending horizontally at the tongue shape. Therefore, when the blades rotate to generate a wake flow to blow on a surface of the volute sidewall at the tongue shape, noise generated by the centrifugal fan can be reduced.

1 . A centrifugal fan, suitable for a portable electrical apparatus, comprising: 
 a casing, the casing having a volute sidewall to define a cavity and an outlet, wherein a tongue shape is formed from the volute sidewall on at least one side of the outlet;    blades disposed around and vertically with a rotational axis on the casing; and    at least one groove set on the volute sidewall, the groove substantially extending horizontally at the tongue shape.    
   
   
       2 . The centrifugal fan according to  claim 1 , wherein the portable electrical apparatus is a notebook personal computer (PC).  
   
   
       3 . The centrifugal fan according to  claim 1 , wherein the groove has a rectangular cross-section.  
   
   
       4 . The centrifugal fan according to  claim 1 , wherein the groove has a rounded cross-section  
   
   
       5 . The centrifugal fan according to  claim 1 , wherein the groove is such located that a part of the groove faces the blades along a height direction of the blades.  
   
   
       6 . The centrifugal fan according to  claim 5 , wherein the groove is such located that the groove faces the blades at a midpoint of the height direction of the blades.  
   
   
       7 . A casing of centrifugal fan, suitable for a portable electrical apparatus, comprising: 
 a bottom plate;    a volute sidewall to define a cavity and an outlet, wherein a tongue shape is formed from the volute sidewall on at least one side of the outlet; and    at least one groove formed on the tongue shape of the volute sidewall, the groove substantially extending horizontally at the tongue shape.    
   
   
       8 . The casing of centrifugal fan according to  claim 7 , wherein the portable electrical apparatus is a notebook PC.  
   
   
       9 . The casing of centrifugal fan according to  claim 7 , wherein the groove has a rectangular cross-section.  
   
   
       10 . The casing of centrifugal fan according to  claim 7 , wherein the groove has a rounded cross-section.  
   
   
       11 . The casing of centrifugal fan according to  claim 7 , wherein the bottom plate rotatably supports blades thereon, and wherein the groove is such located that a part of the groove faces the blades along a height direction of the blades after the blades are supported on the bottom plate.  
   
   
       12 . The casing of centrifugal fan according to  claim 11 , wherein the groove is such located that the groove faces the blades at a midpoint of the height direction of the blades.