Blower fan

Abstract

In a blower fan according to a preferred embodiment of the present invention, a stationary portion of a motor portion includes a stator, a bearing portion, and a holding portion to which both the stator and the bearing portion are fixed, while a rotating portion includes a central rotating portion, and an annular cup portion fixed to the central rotating portion. The central rotating portion includes a shaft, a bearing opposing portion, and a cylindrical seal portion. The cup portion includes a cylindrical cup inner wall portion fixed to an outer circumferential surface of the cylindrical seal portion, a cup top plate portion, and a cup outer wall portion. A seal portion having a surface of a lubricating oil defined therein is defined in a seal gap between an inner circumferential surface of the cylindrical seal portion and an outer circumferential surface of the bearing portion.

What is claimed is: 
     
         1 . A blower fan comprising:
 a plurality of blades arranged in a circumferential direction about a central axis extending in a vertical direction; and   a motor portion arranged to rotate the blades about the central axis; wherein   the motor portion includes:
 a stationary portion; and 
 a rotating portion supported to be rotatable with respect to the stationary portion, and arranged to have the blades fixed thereto; 
   the stationary portion includes:
 a stator; 
 a bearing portion; and 
 an annular holding portion arranged to have the stator fixed to an outer circumferential surface thereof and to have the bearing portion fixed to an inner circumferential surface thereof; 
   the rotating portion includes:
 a central rotating portion supported by the bearing portion; 
 an annular cup portion fixed to the central rotating portion radially outside the central rotating portion; and 
 a rotor magnet fixed to the cup portion, and arranged radially outside the stator; 
   the central rotating portion includes:
 a shaft inserted in the bearing portion, and arranged to rotate about the central axis relative to the bearing portion; 
 a bearing opposing portion arranged to extend radially outward from an upper end of the shaft; and 
 a cylindrical seal portion arranged to extend downward from the bearing opposing portion radially outside the bearing portion; 
   the cup portion includes:
 a cylindrical cup inner wall portion fixed to an outer circumferential surface of the cylindrical seal portion; 
 a cup top plate portion arranged to extend radially outward from an upper end portion of the cup inner wall portion; and 
 a cylindrical cup outer wall portion arranged to extend downward from an outer edge portion of the cup top plate portion; 
   an inner circumferential surface of the cylindrical seal portion and an outer circumferential surface of the bearing portion are arranged to together define a seal gap therebetween, the seal gap including a seal portion having a surface of a lubricating oil defined therein;   an inner circumferential surface of the bearing portion and an outer circumferential surface of the shaft are arranged to together define a radial gap therebetween, the radial gap including a radial bearing portion arranged to radially support the shaft;   a lower surface of the bearing opposing portion and an upper surface of the bearing portion are arranged to together define a gap therebetween, and the lubricating oil is arranged in this gap;   the shaft, the bearing opposing portion, and the cylindrical seal portion are defined by a single continuous electrically conductive member;   the cup inner wall portion, the cup top plate portion, and the cup outer wall portion are defined single continuous insulating member; and   the cup inner wall portion and the holding portion are opposed to each other in the vertical direction with an annular horizontal gap intervening therebetween, radially between the cylindrical seal portion and the stator.   
     
     
         2 . The blower fan according to  claim 1 , further comprising a thrust dynamic pressure bearing portion arranged to axially support the bearing opposing portion, and defined in the gap defined between the lower surface of the bearing opposing portion and the upper surface of the bearing portion. 
     
     
         3 . The blower fan according to  claim 1 , wherein the holding portion is defined by an insulating member. 
     
     
         4 . The blower fan according to  claim 1 , wherein an outer circumferential surface of the cup inner wall portion includes an inclined surface which is angled radially outward with increasing height. 
     
     
         5 . The blower fan according to  claim 2 , wherein an outer circumferential surface of the cup inner wall portion includes an inclined surface which is angled radially outward with increasing height. 
     
     
         6 . The blower fan according to  claim 1 , wherein
 a lower end of the cylindrical seal portion is arranged at a level lower than that of a lower end of the cup inner wall portion;   the holding portion includes a cylindrical radially opposing portion arranged radially opposite the outer circumferential surface of the cylindrical seal portion;   the horizontal gap is defined between the radially opposing portion and the cup inner wall portion; and   an inner circumferential surface of the radially opposing portion and the outer circumferential surface of the cylindrical seal portion are arranged to together define a vertical gap continuous with the horizontal gap therebetween.   
     
     
         7 . The blower fan according to  claim 2 , wherein
 a lower end of the cylindrical seal portion is arranged at a level lower than that of a lower end of the cup inner wall portion;   the holding portion includes a cylindrical radially opposing portion arranged radially opposite the outer circumferential surface of the cylindrical seal portion;   the horizontal gap is defined between the radially opposing portion and the cup inner wall portion; and   an inner circumferential surface of the radially opposing portion and the outer circumferential surface of the cylindrical seal portion are arranged to together define a vertical gap continuous with the horizontal gap therebetween.   
     
     
         8 . The blower fan according to  claim 6 , wherein
 the stator includes:
 an annular core back; 
 a plurality of teeth arranged to project radially outward from the core back; and 
 coils each of which is defined by a conducting wire wound around a separate one of the teeth; 
   an inner circumferential surface of the core back is fixed to an outer circumferential surface of the radially opposing portion; and   an upper end of the radially opposing portion is arranged at a level higher than that of an upper end of the core back.   
     
     
         9 . The blower fan according to  claim 7 , wherein
 the stator includes:
 an annular core back; 
 a plurality of teeth arranged to project radially outward from the core back; and 
 coils each of which is defined by a conducting wire wound around a separate one of the teeth; 
   an inner circumferential surface of the core back is fixed to an outer circumferential surface of the radially opposing portion; and   an upper end of the radially opposing portion arranged at a level higher than that of an upper end of the core back.   
     
     
         10 . The blower fan according to  claim 1 , wherein
 a lower end of the cylindrical seal portion is arranged at a level lower than that of a lower end of the cup inner wall portion; and   the outer circumferential surface of the cylindrical seal portion includes an inclined surface which is angled radially inward with decreasing height between the lower end of the cup inner wall portion and the lower end of the cylindrical seal portion.   
     
     
         11 . The blower fan according to  claim 1 , wherein the outer circumferential surface of the cylindrical seal portion includes a recessed portion or a raised portion, while an inner circumferential surface of the cup inner wall portion includes a raised portion or a recessed portion to be fitted to the recessed portion or the raised portion of the outer circumferential surface of the cylindrical seal portion. 
     
     
         12 . The blower fan according to  claim 1 , wherein the bearing portion includes:
 a sleeve; and   a bearing housing arranged to cover an outer circumferential surface and a lower surface of the sleeve.   
     
     
         13 . The blower fan according to  claim 1 , further comprising a housing arranged to accommodate the motor portion and the blades, wherein
 the housing includes:
 an upper plate portion arranged to cover an upper side of the blades; 
 a lower plate portion arranged to cover a lower side of the blades, and arranged to have the motor portion fixed thereto; and 
 a side wall portion arranged to cover a lateral side of the blades; 
   at least one of the upper and lower plate portions includes an air inlet; and   the upper plate portion, the side wall portion, and the lower plate portion are arranged to together define an air outlet on the lateral side of the blades.