Axial fan

Abstract

An axial fan includes a rotor portion including a shaft arranged to extend along a central axis extending in a vertical direction; a stator portion arranged radially opposite to the rotor portion; and an impeller hub fixed to the rotor portion, and arranged to be capable of rotating integrally with the rotor portion. The impeller hub is an injection molded article, and includes a hub top plate portion arranged to extend perpendicularly to an axial direction; a hub tubular portion being tubular, and arranged to extend axially downward from an outer edge of the hub top plate portion; a plurality of blades arranged in a circumferential direction on an outer surface of the hub tubular portion; and an inner fixing portion arranged radially inward of the hub tubular portion. The rotor portion includes a rotor tubular portion being tubular and arranged to extend in the axial direction. The inner fixing portion includes a first region arranged radially opposite to an outer surface of the rotor tubular portion with a gap therebetween, and having a weld defined in a radially inner surface thereof; and a second region arranged to be in contact with at least a portion of the outer surface of the rotor tubular portion.

What is claimed is: 
     
         1 . An axial fan comprising:
 a rotor portion including a shaft arranged to extend along a central axis extending in a vertical direction;   a stator portion arranged radially opposite to the rotor portion; and   an impeller hub fixed to the rotor portion, and arranged to be capable of rotating integrally with the rotor portion; wherein   the impeller hub is an injection molded article, and includes:
 a hub top plate portion arranged to extend perpendicularly to an axial direction; 
 a hub tubular portion being tubular, and arranged to extend axially downward from an outer edge of the hub top plate portion; 
 a plurality of blades arranged in a circumferential direction on an outer surface of the hub tubular portion; and 
 an inner fixing portion arranged radially inward of the hub tubular portion; 
   the rotor portion includes a rotor tubular portion being tubular and arranged to extend in the axial direction; and   the inner fixing portion includes:
 a first region arranged radially opposite to an outer surface of the rotor tubular portion with a gap therebetween, and having a weld defined in a radially inner surface thereof; and 
 a second region arranged to be in contact with at least a portion of the outer surface of the rotor tubular portion. 
   
     
     
         2 . The axial fan according to  claim 1 , wherein
 the inner fixing portion includes a plurality of the second regions; and   the plurality of second regions are arranged at regular intervals in the circumferential direction.   
     
     
         3 . The axial fan according to  claim 1 , wherein the inner fixing portion is tubular, extending in the axial direction. 
     
     
         4 . The axial fan according to  claim 1 , wherein
 the hub top plate portion includes a gate mark defined in an upper or lower surface thereof;   the inner fixing portion includes:
 a first wall portion arranged radially outside of the gate mark; and 
 a second wall portion arranged circumferentially adjacent to the first wall portion; and 
   the first wall portion includes the second region.   
     
     
         5 . The axial fan according to  claim 1 , wherein
 the hub top plate portion includes a gate mark defined in an upper or lower surface thereof;   the inner fixing portion includes:
 a first projecting portion arranged to project radially inward from an inner surface of the hub tubular portion; and 
 a second projecting portion arranged to project radially inward from the inner surface of the hub tubular portion to a greater extent than the first projecting portion; 
   a shortest circumferential distance between the first projecting portion and the gate mark is greater than a shortest circumferential distance between the second projecting portion and the gate mark; and   the second projecting portion is arranged to be in radial contact with the outer surface of the rotor tubular portion.   
     
     
         6 . An axial fan comprising:
 a rotor portion including a shaft arranged to extend along a central axis extending in a vertical direction;   a stator portion arranged radially opposite to the rotor portion; and   an impeller hub fixed to the rotor portion, and arranged to be capable of rotating integrally with the rotor portion; wherein   the impeller hub is an injection molded article, and includes:
 a hub top plate portion arranged to extend perpendicularly to an axial direction; 
 a hub tubular portion being tubular, and arranged to extend axially downward from an outer edge of the hub top plate portion; 
 a plurality of blades arranged in a circumferential direction on an outer surface of the hub tubular portion; and 
 an inner fixing portion arranged radially inward of the hub tubular portion; 
   the hub top plate portion includes a plurality of gate marks arranged in the circumferential direction in an upper or lower surface thereof;   the rotor portion includes a rotor tubular portion being tubular and arranged to extend in the axial direction; and   at least a portion of an outer surface of the rotor tubular portion is arranged to be in contact with an inner surface of a portion of the inner fixing portion which lies in a region between a middle position between each gate mark and a circumferentially adjacent one of the gate marks and a middle position between the gate mark and another circumferentially adjacent one of the gate marks.   
     
     
         7 . The axial fan according to  claim 6 , wherein the gate marks are arranged at regular intervals in the circumferential direction. 
     
     
         8 . The axial fan according to  claim 6 , wherein at least a portion of a region of contact between an inner surface of the inner fixing portion and the outer surface of the rotor tubular portion is arranged radially outside of the gate mark and on an imaginary line joining the gate mark and the central axis. 
     
     
         9 . The axial fan according to  claim 6 , wherein the inner fixing portion is tubular, extending in the axial direction. 
     
     
         10 . The axial fan according to  claim 6 , wherein
 the inner fixing portion includes:
 a first wall portion including a region overlapping with the gate mark when viewed in a radial direction; and 
 a second wall portion arranged circumferentially adjacent to the first wall portion; and 
   the rotor tubular portion is arranged to be in contact with an inner surface of the first wall portion.   
     
     
         11 . The axial fan according to  claim 6 , wherein
 the inner fixing portion includes:
 a first projecting portion arranged to project radially inward from an inner surface of the hub tubular portion; and 
 a second projecting portion arranged to project radially inward from the inner surface of the hub tubular portion to a greater extent than the first projecting portion; 
   a shortest circumferential distance between the first projecting portion and the gate mark is greater than a shortest circumferential distance between the second projecting portion and the gate mark; and   the second projecting portion is arranged to be in radial contact with the outer surface of the rotor tubular portion.