Mini axial fan with an improved core shaft structure

Abstract

A mini axial fan includes a fan housing and a fan unit, which is mounted in the fan housing. The fan unit has a hub with integrated blades around the periphery and integrated axles at front and back sides, and two metal pins respectively press-fitted into a respective blind hole in the free end of each of the axles for rotatably supporting the fan unit on a respective bearing in the fan housing. The fan unit is injection molded from plastics and then the metal pins are installed in the fan unit so that the precision of the metal pins is maintained and the manufacturing cost of the fan unit is reduced.

1 . A mini axial fan, comprising a fan housing and a fan unit mounted in said fan housing, wherein said fan unit comprises:
 a hub, said hub defining a backward hole;   a plurality of blades formed integral with and radially arranged around the periphery of said hub;   two axles respectively extending through the center of a front side and through the center of a back side of said hub and axially aligned with each other, each said axle having a free end and a blind hole axially defined in the free end; and   two pins respectively press-fitted into the blind holes of said axles for rotatably supporting said fan unit in said fan housing.   
   
   
       2 . The mini axial fan as claimed in  claim 1 , wherein said fan housing is a rectangular plastic frame shell, comprising a circular fan accommodation chamber, and two bearings respectively disposed at top and bottom sides of said circular fan accommodation chamber and facing each other, each said bearing having a recessed hole at the center thereof; and said fan unit is mounted in said circular fan accommodation chamber between said bearings, having said pins positioned in the recessed holes of said bearings. 
   
   
       3 . The mini axial fan as claimed in  claim 2 , wherein said fan housing further comprises two bearing holders respectively disposed at top and bottom sides of said circular fan accommodation chamber to support said bearings in place, a plurality of radial ribs respectively equiangularly spaced around said bearing holders and respectively connected between said bearing holders and the periphery of said fan housing, and a motor stator affixed to one said bearing holder; and said fan unit further comprises a motor rotor mounted inside said fan hub. 
   
   
       4 . The mini axial fan as claimed in  claim 2 , wherein each said pin has an outer end terminating in a conical point outside the respective axle and positioned in the recessed hole of a respective one of said bearings. 
   
   
       5 . The mini axial fan as claimed in  claim 1 , wherein said pins are made of a high carbon steel. 
   
   
       6 . The mini axial fan as claimed in  claim 1 , wherein said pins are made of zirconium.