Axial flow fan and outdoor unit for air conditioner

Abstract

Provided are an axial flow fan and an air conditioner outdoor unit including the axial flow fan. The axial flow fan includes a hub and blades disposed on an outer surface of the hub. Each of the blades satisfies that a shortest distance measured from an imaginary line (L 2 ) passing through a center of the hub to a front end of an outer edge of the blade is greater than a shortest distance measured from the imaginary line (L 2 ) to a rear end of the outer edge of the blade. The front end of the outer edge of the blade is a leading end in a rotation direction of the blade, and the rear end of the outer edge of the blade is a trailing end in the rotation direction of the blade. Owing to the shape of the blade, noise can be reduced while increasing the flowrate of air.

1 . An axial flow fan comprising:
 a hub; and   a plurality of blades disposed on an outer surface of the hub,   wherein each of the blades satisfies that a shortest distance measured from an imaginary line (L 2 ) passing through a center of the hub to a front end of an outer edge of the blade is greater than a shortest distance measured from the imaginary line (L 2 ) to a rear end of the outer edge of the blade,   wherein the front end of the outer edge of the blade is a leading end in a rotation direction of the blade, and the rear end of the outer edge of the blade is a trailing end in the rotation direction of the blade.   
     
     
         2 . The axial flow fan according to  claim 1 , wherein each of blades comprises a leading edge in the rotation direction thereof, a trailing edge in the rotation direction thereof, and a tip as the outer edge,
 wherein a shortest distance (RL 2 ) measured from the imaginary line (L 2 ) passing through the center of the hub to a front end of the tip close to the leading edge is greater than a shortest distance (RT 2 ) measured from the imaginary line (L 2 ) to a rear end of the tip close to the trailing edge.   
     
     
         3 . The axial flow fan according to  claim 2 , wherein a shortest distance from the imaginary line (L 2 ) to the tip is gradually decreased in a direction from the front end of the tip close to the leading edge to the rear end of the tip close to the trailing edge. 
     
     
         4 . The axial flow fan according to  claim 1 , wherein the hub has a cylindrical shape. 
     
     
         5 . The axial flow fan according to  claim 1 , further comprising a rotation shaft coupled to the hub for rotating the axial flow fan. 
     
     
         6 . The axial flow fan according to  claim 5 , wherein the rotation shaft is coupled to the center of the hub. 
     
     
         7 . The axial flow fan according to  claim 5 , wherein if the blades are rotated, air is forced to flow along the rotation shaft. 
     
     
         8 . An axial flow fan comprising:
 a hub; and   a plurality of blades disposed on an outer surface of the hub,   wherein each of the blades satisfies that when the blade is rotated, a trajectory formed by a front end of an outer edge of the blade is greater than a trajectory formed by a rear end of the outer edge of the blade.   
     
     
         9 . The axial flow fan according to  claim 8 , wherein each of blades comprises a leading edge in a rotation direction thereof, a trailing edge in the rotation direction thereof, and a tip as the outer edge,
 wherein when the blade is rotated, the diameter of a trajectory formed by a portion of the blade close to the leading edge is greater than the diameter of a trajectory formed by another portion of the blade close to the trailing edge.   
     
     
         10 . The axial flow fan according to  claim 9 , wherein the diameter of a trajectory formed by rotation of the blade is gradually reduced in a direction from a front end of the tip close to the leading edge to a rear end of the tip close to the trailing edge. 
     
     
         11 . The axial flow fan according to  claim 8 , wherein a trajectory formed by rotation of the blade has a cylindrical shape with a diameter gradually reducing in a direction of air blown by the axial flow fan. 
     
     
         12 . An outer unit of an air conditioner, the outer unit comprising:
 a casing comprising a suction hole and a discharge hole for inflows and outflows of air;   an outdoor heat exchanger disposed in the casing to allow a flow of refrigerant therein;   an axial flow fan configured to blow outdoor air for heat exchange between the outdoor air and the refrigerant flowing in the outdoor heat exchanger;   a motor configured to rotate the axial flow fan; and   an orifice configured to guide outdoor air blown by the axial flow fan to an outside area of the casing through the discharge hole,   wherein the axial flow fan comprises a blade, and the blade satisfies that a shortest distance measured from an imaginary line (L 2 ) passing through a center of a hub of the blade to a front end of an outer edge of the blade is different from a shortest distance measured from the imaginary line (L 2 ) to a rear end of the outer edge of the blade,   wherein the front end of the outer edge of the blade is a leading end in a rotation direction of the blade, and the rear end of the outer edge of the blade is a trailing end in the rotation direction of the blade.   
     
     
         13 . The outdoor unit according to  claim 12 , wherein the orifice is located at downstream side of the axial flow fan in a direction in which air flows by the axial flow fan. 
     
     
         14 . The outdoor unit according to  claim 12 , wherein the orifice is overlapped with a portion of the blade close to a trailing edge of the blade. 
     
     
         15 . The outdoor unit according to  claim 12 , wherein the orifice has a ring shape. 
     
     
         16 . The outdoor unit according to  claim 12 , further comprising a compressor configured to compress the refrigerant. 
     
     
         17 . The outdoor unit according to  claim 12 , wherein the suction hole of the casing is formed in a rear side of the casing to introduce outdoor air into the casing. 
     
     
         18 . The outdoor unit according to  claim 12 , wherein the discharge hole of the casing is formed in a front side of the casing to discharge outdoor air from the casing after the outdoor air exchanges heat with the refrigerant flowing in the outdoor heat exchanger.