Fan blades

Abstract

A blade for an axial fan, including at least a front edge portion, a back edge portion, and multiple pressure balance holes. The front edge portion operates to blow air from the outside of the blade, the back edge portion operates to blow air to the outside of the blade, and the pressure balance hole is disposed on the back edge portion. The pressure balance holes are adapted to balance pressure and reduce pressure difference between the front side and the back side of the blade, eliminating backflow phenomenon caused by separation of boundary layer airflow at the back edge portion on a windward side of the blade and thus reducing power consumption and noise, and preventing dust from settling on the back edge portion on the windward side of the blade.

1 . A blade for an axial fan, comprising
 a front edge portion;   a back edge portion; and   multiple pressure balance holes; wherein   said front edge portion operates to blow air from the outside of the blade;   said back edge portion operates to blow air to the outside of the blade; and   said pressure balance hole is disposed on said back edge portion.   
   
   
       2 . The blade of  claim 1 , wherein said pressure balance holes are distributed in an array, uniformly or randomly. 
   
   
       3 . The blade of  claim 1 , wherein said pressure balance holes are circular holes, non-circular holes, straight through holes or inclined through holes. 
   
   
       4 . The blade of  claim 1 , wherein said pressure balance holes form a hole net whereby adjusting pressure on both side of the blade. 
   
   
       5 . The blade of  claim 1 , wherein a diameter of said pressure balance hole ranges from 0.1 mm to 100 mm. 
   
   
       6 . The blade of  claim 1 , wherein said pressure balance hole is a circular hole or a non-circular hole. 
   
   
       7 . A blade for a centrifugal fan, comprising
 a front edge portion;   a back edge portion; and   multiple pressure balance holes; wherein   said front edge portion operates to blow air from the outside of the blade;   said back edge portion operates to blow air to the outside of the blade; and   said pressure balance hole is disposed on said back edge portion.   
   
   
       8 . The blade of  claim 7 , wherein said pressure balance holes are distributed in an array, uniformly or randomly. 
   
   
       9 . The blade of  claim 7 , wherein said pressure balance holes are circular holes, non-circular holes, straight through holes or inclined through holes. 
   
   
       10 . The blade of  claim 7 , wherein said pressure balance holes form a hole net whereby adjusting pressure on both side of the blade. 
   
   
       11 . The blade of  claim 7 , wherein a diameter of said pressure balance hole ranges from 0.1 mm to 100 mm. 
   
   
       12 . The blade of  claim 7 , wherein said pressure balance hole is a circular hole or a non-circular hole.