Axial fan

Abstract

An axial fan is disclosed herein. The axial fan may include a hub, to which a central shaft may be coupled, and a plurality of blades coupled to an outside of the hub to rotate therewith. Each blade of the plurality of blades may include a hub connection portion that defines a first end of the respective blade, the hub connection portion being coupled to an outer circumferential surface of the hub, a tip that defines a second end of the predetermined blade, a first wing that extends at a first predetermined gradient from the tip, and a second wing that extends from the first wing towards the hub, the second wing having a second predetermined gradient.

What is claimed is: 
     
         1 . An axial fan, comprising:
 a hub to which a central shaft is coupled; and   a plurality of blades coupled to the hub to rotate therewith, wherein each blade of the plurality of blades comprises:
 a hub connection portion that defines a first end of the respective blade, the hub connection portion being coupled to an outer circumferential surface of the hub; 
 a tip that defines a second end of the blade; 
 a first wing that extends at a first predetermined gradient from the tip; and 
 a second wing that extends from the first wing towards the hub, the second wing having a second predetermined gradient. 
   
     
     
         2 . The axial fan according to  claim 1 , wherein the hub has a cylindrical shape, and wherein the hub comprises:
 a front surface that faces an air blow direction;   a rear surface that faces an air discharge direction; and   an outer circumferential surface that defines an outer circumference of the cylindrical shape.   
     
     
         3 . The axial fan according to  claim 2 , wherein each blade of the plurality of blades further comprises a boundary that divides the first wing from the second wing, and wherein the second wing is bent from the boundary towards the front surface of the hub. 
     
     
         4 . The axial fan according to  claim 3 , wherein each blade of the plurality of blades further comprises:
 a leading edge that defines a front end of the respective blade in a rotational direction; and   a trailing edge that defines a rear end of the respective blade in the rotational direction, and wherein the boundary comprises:
 a first end formed at the trailing edge; and 
 a second end formed at the leading edge. 
   
     
     
         5 . The axial fan according to  claim 4 , wherein an angle at which the second wing is bent from the second end is greater than an angle at which the second wing is bent from the first end. 
     
     
         6 . The axial fan according to  claim 5 , wherein the second wing extends from the first end to the hub in a direction corresponding to an extension direction of the first wing and is bent at a predetermined angle to extend from a second end in the extension direction of the first wing. 
     
     
         7 . The axial fan according to  claim 6 , wherein the angle between the first wing and the second wing is about 0° at the first end and substantially ranges from about 50° to about 70° at the second end. 
     
     
         8 . The axial fan according to  claim 2 , wherein an area of a portion at which the hub connection portion and the outer circumferential surface of the hub are coupled is variable in a clockwise or counterclockwise direction. 
     
     
         9 . The axial fan according to  claim 8 , wherein the hub connection portion comprises:
 a front end that extends along the front surface of the hub; and   a rear end that extends at an incline with respect to the rear surface of the hub.   
     
     
         10 . The axial fan according to  claim 9 , wherein a distance between the front end and the rear end gradually increases in the counterclockwise direction of the outer circumferential surface of the hub and gradually decreases in the clockwise direction of the outer circumferential surface of the hub. 
     
     
         11 . The axial fan according to  claim 2 , wherein a virtual circle (C) that connects tips of the plurality of blades to each other is defined, and wherein a ratio of a radius (R 1 ) of the virtual circle to a radius (R 2 ) of the outer circumferential surface from a center of the hub ranges from about 10% to about 25%. 
     
     
         12 . The axial fan according to  claim 1 , wherein the first and second wings are integrated with each other. 
     
     
         13 . An outdoor device of an air conditioner comprising the axial fan of  claim 1 . 
     
     
         14 . An axial fan, comprising:
 a hub having a front surface, a rear surface, and an outer circumferential surface; and   a plurality of blades coupled to the outer circumferential surface of the hub to rotate therewith, wherein each blade of the plurality of blades comprises:
 a tip that defines an outer end of the blade; 
 an outer wing that extends at a first predetermined gradient from the tip; 
 an inner wing that extends from the outer wing towards the hub, the inner wing having a second predetermined gradient; and 
 a boundary defined between the outer wing and the inner wing, wherein the boundary is bent from the outer wing toward the inner wing. 
   
     
     
         15 . The axial fan according to  claim 14 , wherein the first predetermined gradient and the second predetermined gradient are different from each other. 
     
     
         16 . The axial fan according to  claim 14 , further comprising a central shaft to which the hub is coupled, wherein an angle between the outer wing and the central shaft is greater than an angle between the inner wing and the central shaft. 
     
     
         17 . The axial fan according to  claim 14 , wherein each blade of the plurality of blades further comprises a leading edge that defines a front end in a rotational direction and a trailing edge that defines a rear end in the rotational direction, wherein the boundary comprises a first end that contacts the trailing edge and a second end that contacts the leading edge, and wherein an angle at which the inner wing is bent from the second end is greater than an angle at which the inner wing is bent from the first end. 
     
     
         18 . The axial fan according to  claim 14 , wherein a pitch angle of the respective blade gradually increases toward the hub. 
     
     
         19 . An outdoor device of an air conditioner comprising the axial fan of  claim 14 . 
     
     
         20 . An axial fan, comprising:
 a hub to which a central shaft is coupled; and   a plurality of blades coupled to the hub to rotate therewith, wherein each blade of the plurality of blades comprises:
 a first wing that extends at a first predetermined gradient from a tip; thereof; 
 a second wing that extends from the first wing towards the hub, the second wing having a second predetermined gradient; and 
 a boundary that divides the first wing from the second wing, and wherein the second wing is bent from the boundary towards a front surface of the hub. 
   
     
     
         21 . The axial fan according to  claim 20 , wherein each blade of the plurality of blades further comprises:
 a leading edge that defines a front end of the respective blade in a rotational direction; and   a trailing edge that defines a rear end of the respective blade in the rotational direction, and wherein the boundary comprises:
 a first end formed at the trailing edge; and 
 a second end formed at the leading edge, wherein an angle at which the second wing is bent from the second end is greater than an angle at which the second wing is bent from the first end. 
   
     
     
         22 . The axial fan according to  claim 21 , wherein the second wing extends from the first end to the hub in a direction corresponding to an extension direction of the first wing and is bent at a predetermined angle to extend from the second end in the extension direction of the first wing. 
     
     
         23 . The axial fan according to  claim 22 , wherein the angle between the first wing and the second wing is about 0° at the first end and substantially ranges from about 50° to about 70° at the second end. 
     
     
         24 . The axial fan according to  claim 20 , wherein a virtual circle (C) that connects tips of the plurality of blades to each other is defined, and wherein a ratio of a radius (R 1 ) of the virtual circle to a radius (R 2 ) of the outer circumferential surface from a center of the hub ranges from about 10% to about 25%. 
     
     
         25 . The axial fan according to  claim 20 , wherein the first and second wings are integrated with each other. 
     
     
         26 . An outdoor device of an air conditioner comprising the axial fan of  claim 20 .