Centrifugal fan

Abstract

A centrifugal fan preferably includes a stator portion; a substantially cylindrical rotor holder; an annular support plate secured to an outer circumferential surface and/or a lower end portion of the rotor holder; and a plurality of blades secured to the support plate. The support plate is integrally defined by a substantially annular blade support portion arranged radially farthest from the rotor holder to support the plurality of blades; a cylindrical portion arranged radially closest to the rotor holder to encircle the outer circumferential surface of the rotor holder; and a sloping portion arranged between the blade support portion and the cylindrical portion to slope from an upper end portion of the cylindrical portion to the blade support portion.

1 . A centrifugal fan comprising:
 a stator portion;   a substantially cylindrical rotor holder;   an annular support plate secured to an outer circumferential surface and/or a lower end portion of the rotor holder, and arranged to spread radially outward from the rotor holder; and   a plurality of blades secured to the support plate, arranged to be spaced from the outer circumferential surface of the rotor holder, and arranged in a circumferential direction with respect to the rotor holder; wherein   the support plate defined by an integral structure including:
 a substantially annular blade support portion arranged radially farthest from the rotor holder to support the plurality of blades; 
 a cylindrical portion arranged radially closest to the rotor holder to encircle the outer circumferential surface of the rotor holder; and 
 a sloping portion arranged between the blade support portion and the cylindrical portion to slope from an upper end portion of the cylindrical portion to the blade support portion. 
   
   
   
       2 . The centrifugal fan according to  claim 1 , wherein the rotor holder includes, at the lower end portion thereof, a protruding portion arranged to protrude radially outward from the rotor holder, and arranged to be insert-molded with a lower end portion of the cylindrical portion of the support plate, so that the support plate is secured to the rotor holder. 
   
   
       3 . The centrifugal fan according to  claim 1 , wherein the cylindrical portion includes a first thickness reducing portion defined therein to extend downward from an axially upper end thereof. 
   
   
       4 . The centrifugal fan according to  claim 3 , wherein the first thickness reducing portion is defined by a plurality of subportions spaced from one another in the circumferential direction. 
   
   
       5 . The centrifugal fan according to  claim 3 , wherein the first thickness reducing portion is defined in a ring shape to surround the rotor holder. 
   
   
       6 . The centrifugal fan according to  claim 3 , wherein the cylindrical portion and the sloping portion have substantially the same thickness. 
   
   
       7 . The centrifugal fan according to  claim 2 , wherein
 the protruding portion is defined by a plurality of subportions spaced from one another in the circumferential direction, the plurality of subportions of the protruding portion being insert-molded with the lower end portion of the cylindrical portion of the support plate, whereby the support plate is secured to the rotor holder; and   the cylindrical portion includes, at positions corresponding to the plurality of subportions of the protruding portion, columnar increased thickness portions arranged to protrude radially outward.   
   
   
       8 . The centrifugal fan according to  claim 7 , wherein at a circumferential position where no subportion of the protruding portion is provided, the cylindrical portion includes a second thickness reducing portion defined on a side thereof facing the sloping portion to extend upward from an axially lower end of the cylindrical portion. 
   
   
       9 . The centrifugal fan according to  claim 7 , wherein the cylindrical portion includes substantially the same thickness as that of the sloping portion, except at positions where the increased thickness portions are provided. 
   
   
       10 . The centrifugal fan according to  claim 7 , wherein each of the increased thickness portions includes a circumferential dimension substantially equal to the thickness of the sloping portion and the thickness of the cylindrical portion where no increased thickness portion is provided. 
   
   
       11 . The centrifugal fan according to  claim 1 , wherein the plurality of blades are integral with the support plate. 
   
   
       12 . The centrifugal fan according to  claim 1 , wherein the stator portion is arranged radially inward of the cylindrical portion. 
   
   
       13 . The centrifugal fan according to  claim 1 , wherein an inner circumferential portion of the cylindrical portion is in contact with an outer circumferential portion of the rotor holder. 
   
   
       14 . The centrifugal fan according to  claim 1 , wherein the cylindrical portion and the rotor holder are arranged to define a gap between an inner circumferential portion of the cylindrical portion and an outer circumferential portion of the rotor holder. 
   
   
       15 . The centrifugal fan according to  claim 1 , wherein the sloping portion is arranged to slope in a curved configuration.