Air blower

Abstract

An air blower is provided with a drive motor and an air blowing fan which has a hub mounted to the drive motor and blades which are provided to the hub. The air blower is characterized in that serrations comprising triangle-shaped protrusions are provided to the front edge of each of the blades so as to be arranged along the front edge and in that the pitch, the height, or the direction of the serrations is changed according to the flow of air at a radial position on the air blowing fan.

What is claimed is: 
     
         1 . A blower comprising
 a drive motor and   a blower fan having a hub which is attached to said drive motor, and a plurality of blades which are provided at said hub, wherein   said blades are provided at their blade leading edge parts with serrations comprised of pluralities of triangular shape projecting parts along the blade leading edge parts and said serrations are changed in pitch, height, or direction according to the flows of air at radial direction positions of said blower fan.   
     
     
         2 . The blower according to  claim 1 , wherein said serrations have a pitch or height which becomes larger as the serrations are further to the blade outside diameter side. 
     
     
         3 . The blower according to  claim 1 , wherein said serrations have an angle of vertices which becomes smaller as the serrations are further to the blade outside diameter side. 
     
     
         4 . The blower according to  claim 1 , wherein said serrations have a direction in the circumferential direction of the blower fan. 
     
     
         5 . The blower according to  claim 1 , wherein said serrations have a direction in the direction of flow of air other than the circumferential direction of the blower fan. 
     
     
         6 . The blower according to  claim 1 , wherein said serrations have a pitch, height, or direction made a magnitude or a direction corresponding to a back flow at the blade end part. 
     
     
         7 . The blower according to  claim 1 , wherein said blades have a blade trailing edge part with serrations comprised of a plurality of triangular shape projecting parts along the blade trailing edge part. 
     
     
         8 . The blower according to  claim 7 , wherein said serrations of said blade trailing edge part have a pitch or height smaller than said serrations of said blade leading edge part. 
     
     
         9 . The blower according to  claim 7 , wherein said serrations of said blade leading edge part and said serrations of said blade trailing edge part are different in set position in radial direction position of the blower fan. 
     
     
         10 . A blower fan having a hub which adapts to be attached to a drive unit, and a plurality of blades which are provided at said hub, wherein
 each said blade has a first portion of a blade leading edge part of said blade which has a first distance in the radial direction from the center of rotation of said blade, and a second portion of a blade leading edge part of said blade which has a second distance in the radial direction from the center of rotation of said blade,   said blade leading edge part is provided with a plurality of serrations which stick out to an upstream side of flow of air, wherein said serrations have first slanted sides which are slanted with respect to a direction of flow of air, and second slanted sides which are slanted in a different direction from said first slanted sides with respect to a direction of flow of air, and   at least one of a pitch, height, and direction of said projections at said first portion differs from at least one of a pitch, height, and direction of said projections at said second portion.