Blower

Abstract

A blower includes a fan that has blades and generates an air flow by rotating. Each of the blades has a front edge and a serration provided at least in a part of the front edge. The serration has tip portions and recessed portions arranged alternately with each other. Each of the blades has a negative pressure surface and one or more ribs protruding from the negative pressure surface. Each of the ribs extends from a corresponding one of the recessed portions, which is designated as a starting point, toward a rear edge of a corresponding one of the blades.

What is claimed is: 
     
         1 . A blower comprising
 a fan that has a plurality of blades and generates an air flow by rotating, wherein   each of the plurality of blades has a front edge and a serration provided at least in a part of the front edge,   the serration has tip portions and recessed portions, which are arranged alternately with each other,   each of the plurality of blades has a negative pressure surface and one or more ribs protruding from the negative pressure surface, and   each of the ribs extends from a corresponding one of the recessed portions, which is designated as a starting point, to a rear edge of a corresponding one of the plurality of blades.   
     
     
         2 . A blower comprising
 an axial fan that has a plurality of blades arranged around a fan axis and rotates around the fan axis, wherein   each of the plurality of blades has:
 a negative pressure surface forming a blade surface on one side in a fan axial direction that is an upstream side in a flow direction of air; 
 a positive pressure surface forming a blade surface on an opposite side of the negative pressure surface; 
 a front edge located on a front side in a rotating direction; and 
 a rear edge located on a rear side in the rotating direction, 
   the front edge of each of the plurality of blades is provided with a serration that has tip portions and recessed portions,   the tip portions and the recessed portions are arranged alternately with each other along the front edge,   the negative pressure surface of each of the plurality of blades is provided with one or more ribs protruding from the negative pressure surface, and   each of the ribs extends from a corresponding one of the recessed portions, which is designated as a starting point, to the rear edge.   
     
     
         3 . The blower according to  claim 2 , wherein
 the ribs are provided in the negative pressure surface, and   the ribs are provided in only a part of the recessed portions.   
     
     
         4 . The blower according to  claim 3 , wherein
 in a serration forming area in which the serration is formed, a portion of the serration forming area located on an inner side of a center of the serration forming area in a radial direction of the axial fan is defined as an inner peripheral portion of the serration, and a portion of the serration forming area located on an outer side of the center of the serration forming area in the radial direction of the axial fan is defined as an outer peripheral portion of the serration, and   a quantity of the ribs provided in the outer peripheral portion of the serration is larger than a quantity of the ribs provided in the inner peripheral portion of the serration.   
     
     
         5 . The blower according to  claim 2 , wherein
 the starting point is located in a deepest portion of the corresponding one of the recessed portions.   
     
     
         6 . The blower according to  claim 2 , wherein
 the ribs extend in a circumferential direction of a circle centering on the fan axis.   
     
     
         7 . The blower according to  claim 2 , wherein
 each of the ribs extends from the corresponding one of the recessed portions, which is designated as the starting point, to the rear edge, which is designated as an end point.   
     
     
         8 . The blower according to  claim 2 , wherein
 the ribs are provided in the negative pressure surface, and   the ribs are designed to have a height that increases from an inner side toward an outer side in a radial direction of the axial fan.   
     
     
         9 . The blower according to  claim 2 , wherein
 the ribs provided in the negative pressure surface are first ribs,   the positive pressure surface is provided with one or more second ribs protruding from the positive pressure surface, and   each of the second ribs extends from a corresponding one of the recessed portions, which is designated as a starting point, to the rear edge.   
     
     
         10 . The blower according to  claim 9 , wherein
 a quantity of the second ribs provided in the positive pressure surface is more than one, and   the second ribs are provided in only a part of the recessed portions.   
     
     
         11 . The blower according to  claim 10 , wherein
 in a serration forming area in which the serration is formed, a portion of the serration forming area located on an inner side of a center of the serration forming area in a radial direction of the axial fan is defined as an inner peripheral portion of the serration, and a portion of the serration forming area located on an outer side of the center of the serration forming area in the radial direction of the axial fan is defined as an outer peripheral portion of the serration, and   a quantity of the second ribs provided in the outer peripheral portion of the serration is larger than a quantity of the second ribs provided in the inner peripheral portion of the serration.   
     
     
         12 . The blower according to  claim 9 , wherein
 a quantity of the second ribs is larger than a quantity of the first ribs.   
     
     
         13 . The blower according to  claim 9 , wherein
 the starting point of each of the second ribs are located in the deepest portions of the corresponding one of the recessed portions.   
     
     
         14 . The blower according to  claim 9 , wherein
 the second ribs extend in a circumferential direction of a circle centering on the fan axis.   
     
     
         15 . The blower according to  claim 9 , wherein
 each of the second ribs extends from the corresponding one of the recessed portions, which is designated as the starting point, to the rear edge, which is designated as an end point.   
     
     
         16 . A blower comprising
 an axial fan that has a plurality of blades arranged around a fan axis and rotates around the fan axis, wherein   each of the plurality of blades has:
 a negative pressure surface forming a blade surface on one side in a fan axial direction that is an upstream side in a flow direction of air; 
 a positive pressure surface forming a blade surface on an opposite side of the negative pressure surface; 
 a front edge located on a front side in a rotating direction; and 
 a rear edge located on a rear side in the rotating direction, 
   the front edge of each of the plurality of blades is provided with a serration that has tip portions and recessed portions arranged alternately with each other,   the tip portions and the recessed portions are arranged alternately with each other along the front edge,   the negative pressure surface of each of the plurality of blades is provided with first ribs protruding from the negative pressure surface,   the positive pressure surface of each of the plurality of blades is provided with second ribs protruding from the positive pressure surface,   each of the first ribs and the second ribs extends in a circumferential direction of a circle centering on the fan axis, from a corresponding one of the recessed portions, which is designated as a starting point, to the rear edge, which is designated as an end point,   in an area in which the serration is provided, a portion of the serration forming area located on an inner side of a center of the serration forming area in a radial direction of the axial fan is defined as an inner peripheral portion of the serration, and a portion of the serration forming area located on an outer side of the center of the serration forming area in the radial direction of the axial fan is defined as an outer peripheral portion of the serration,   a total quantity of the first ribs and the second ribs provided in the outer peripheral portion of the serration is larger than a total quantity of the first ribs and the second ribs provided in the inner peripheral portion of the serration, and a quantity of the second ribs is larger than a quantity of the first ribs.