Heat-dissipating fan

Abstract

A heat-dissipating fan has a housing and an impeller. The housing has a receiving space and one or more guide rings. The receiving space forms an airflow inlet and an airflow outlet. The guide ring is mounted near the airflow outlet and has one or two guide surfaces formed thereon and facing the airflow inlet. The impeller is mounted rotatably in the receiving space and has a hub and multiple blades. Airflow channels formed between adjacent blades each have a cross-section narrowed from a top end of the guide ring to the airflow outlet. Each blade has a receiving notch formed in a bottom edge thereof, corresponding to a cross-section of the guide ring and defines a gap between the blade and the guide ring. Airflow is speeded up in the airflow channels based on Venturi effect, such that a heat-dissipating efficiency of the fan is improved.

1 . A heat-dissipating fan comprising 
 a housing having 
 a receiving space formed in a center of the housing and forming an airflow inlet and an airflow outlet; and  
 at least one guide ring mounted near the airflow outlet and each one having 
 at least one guide surface formed on the guide ring; and  
 
   an impeller mounted rotatably in the receiving space and having 
 a hub; and  
 multiple blades mounted around an outer wall of the hub and forming multiple airflow channels, each of the airflow channels locating between adjacent blades and having a cross-section narrowed from at least one top end, respectively, of the at least one guide ring to the airflow outlet, each of the blades having at least one receiving notch formed in a bottom edge of the blade, corresponding to at least one cross-section, respectively, of the at least one guide ring and defining at least one gap between the bottom edge of the blade and the at least one guide surface of the at least one guide ring.  
   
   
   
       2 . The heat-dissipating fan as claimed in  claim 1 , wherein the housing further has 
 a hub bracket mounted in the receiving space; and    multiple support ribs locating between and connecting to the hub bracket and an inner wall of the receiving space.    
   
   
       3 . The heat-dissipating fan as claimed in  claim 2 , wherein the at least one guide ring is mounted on the supporting ribs.  
   
   
       4 . The heat-dissipating fan as claimed in  claim 1 , wherein at least one of the at least one guide ring has a single guide surface.  
   
   
       5 . The heat-dissipating fan as claimed in  claim 1 , wherein at least one of the at least one guide ring has two guide surfaces.  
   
   
       6 . The heat-dissipating fan as claimed in  claim 1 , wherein housing has a single guide ring.  
   
   
       7 . The heat-dissipating fan as claimed in  claim 1 , wherein the housing has multiple guide rings.  
   
   
       8 . The heat-dissipating fan as claimed in  claim 7 , wherein the guide rings are arranged at intervals and include at least one guide ring with a single guide surface and at least one guide ring with two guide surfaces.