Impeller and centrifugal fan having the same

Abstract

An impeller and a centrifugal fan having the same are provided. The impeller includes a lower shroud, an upper shroud, and a plurality of blades which are arranged along a circumference direction between the lower shroud and the upper shroud. The impeller is rotatable around a rotary shaft. An outside diameter of the lower shroud is equal to or smaller than an inside diameter of the upper shroud. An inside portion of each of the blades has an inclined portion which connects an inside circle portion of the upper shroud and an inside circle portion of the lower shroud.

1 . An impeller comprising:
 a lower shroud;   an upper shroud; and   a plurality of blades which are arranged along a circumference direction between the lower shroud and the upper shroud,   wherein the impeller is rotatable around a rotary shaft,   wherein an outside diameter of the lower shroud is equal to or smaller than an inside diameter of the upper shroud, and   wherein an inside portion of each of the blades has an inclined portion which connects an inside circle portion of the upper shroud and an inside circle portion of the lower shroud.   
     
     
         2 . The impeller according to  claim 1 ,
 wherein in a range where the upper shroud and the blades exist in a planar view, the upper shroud is in contact with the blades.   
     
     
         3 . The impeller according to  claim 1 ,
 wherein each of the plurality of blades has a shape which becomes thinner as separating further from the rotary shaft.   
     
     
         4 . A centrifugal fan comprising:
 the impeller according to  claim 1 ; and   a lower casing which is provided at a lower portion of the impeller,   wherein the lower casing has a protrusion which protrudes toward the impeller in a portion where the upper shroud exists in a planar view, and   wherein air suctioned from a suction opening is discharged outward in a radial direction of the impeller by a centrifugal force from the rotation of the impeller.