Centrifugal fan with low noise

Abstract

A centrifugal fan with low noise includes a housing, a fan wheel and a recess unit. The fan wheel has a hub and a plurality of fan blade extending outward from the hub radially. The housing has a chamber therein to receive the fan wheel and has a recess unit at the surface thereof. The recess unit is composed of a projection part and a recess part for reducing noise transmission greatly.

1 . A centrifugal fan with low noise, comprising: 
 a housing, providing a chamber therein; and    a fan wheel, being received in the chamber;    characterized in that the housing has a recess unit at the surface thereof for reducing noise.    
   
   
       2 . The centrifugal fan with low noise as defined in  claim 1 , wherein the recess unit is composed of at least a projection part and a recess part.  
   
   
       3 . The centrifugal fan with low noise as defined in  claim 2 , wherein the projection part and the recess part is formed with a grid shape.  
   
   
       4 . The centrifugal fan with low noise as defined in  claim 2 , wherein the projection part and the recess part is formed with a parallel shape.  
   
   
       5 . The centrifugal fan with low noise as defined in  claim 1 , wherein the housing has at least an outlet communicating with the chamber.  
   
   
       6 . The centrifugal fan with low noise as defined in  claim 1 , wherein the surface refers to the outer surface and/or the inner surface of the housing.  
   
   
       7 . The centrifugal fan with low noise as defined in  claim 1 , wherein the fan wheel has a hub and a plurality of fan blades extending outward from the hub radially.  
   
   
       8 . The centrifugal fan with low noise as defined in  claim 1 , wherein the housing is integrally made with the recess unit as a single piece.  
   
   
       9 . The centrifugal fan with low noise as defined in  claim 1 , wherein the housing is made as an individual piece from the recess unit.