Impeller and blower

Abstract

An impeller is fixed to a shaft concentric with a center axis extending in an up-down direction and is rotatable about the center axis together with the shaft. The impeller includes a boss portion which is fixed to the shaft and extends in an axial direction, an impeller body portion, a plurality of blade portions arranged on an upper surface of the impeller body portion, and a rib portion arranged on a lower surface of the impeller body portion. The impeller body portion extends downward from an upper end of the boss portion while being widened in a radial direction, and is arranged to surround the boss portion in a circumferential direction. When viewed in the axial direction, a front side end portion of the rib portion is curved toward a rotation direction back side as the rib portion extends from a radial inner side toward a radial outer side.

What is claimed is: 
     
         1 . An impeller which is directly or indirectly fixed to a shaft concentric with a center axis extending in an up-down direction and arranged to rotate about the center axis together with the shaft, the impeller comprising:
 a boss portion which is fixed to the shaft and arranged to extend in an axial direction;   an impeller body portion extending downward from an upper end of the boss portion while being widened in a radial direction, the impeller body portion arranged to surround the boss portion in a circumferential direction;   a plurality of blade portions arranged on an upper surface of the impeller body portion; and   a rib portion arranged on a lower surface of the impeller body portion,   wherein when viewed in the axial direction, a front side end portion as a rotation direction front side end portion of the rib portion is curved toward a rotation direction back side as the rib portion extends from a radial inner side toward a radial outer side.   
     
     
         2 . The impeller of  claim 1 , wherein the rib portion is connected to the boss portion. 
     
     
         3 . The impeller of  claim 1 , wherein the rib portion includes a plurality of rib portions, and the number of the rib portions differs from the number of the blade portions. 
     
     
         4 . The impeller of  claim 1 , wherein a radial outer end of the rib portion is arranged at a radial outer edge of the impeller body portion. 
     
     
         5 . The impeller of  claim 1 , wherein when viewed in the axial direction, a back side end portion as a rotation direction back side end portion of the rib portion is curved toward the rotation direction back side as the rib portion extends from the radial inner side toward the radial outer side. 
     
     
         6 . The impeller of  claim 5 , wherein a dimension between the front side end portion and the back side end portion of the rib portion is substantially uniform. 
     
     
         7 . The impeller of  claim 1 , wherein when viewed in the axial direction, a back side end portion as a rotation direction back side end portion of the rib portion has a straight shape. 
     
     
         8 . The impeller of  claim 1 , wherein when viewed in the axial direction, the rib portion intersects one of the blade portions. 
     
     
         9 . The impeller of  claim 1 , wherein when viewed in the axial direction, the blade portions are curved toward the rotation direction back side as the blade portions extend from the radial inner side toward the radial outer side. 
     
     
         10 . The impeller of  claim 9 , wherein a curvature of the rib portion differs from a curvature of each of the blade portions. 
     
     
         11 . The impeller of  claim 1 , wherein an axial dimension of the rib portion is one half or more of an axial distance between a position, in which the impeller body portion and the boss portion are connected to each other, and a lower end of the impeller body portion. 
     
     
         12 . The impeller of  claim 11 , wherein the axial dimension of the rib portion is equal to the axial distance between the position, in which the impeller body portion and the boss portion are connected to each other, and the lower end of the impeller body portion. 
     
     
         13 . The impeller of  claim 1 , wherein the rib portion includes a plurality of rib portions uniformly arranged along the circumferential direction. 
     
     
         14 . A blower comprising:
 the impeller of  claim 1 ;   a motor provided with the shaft and arranged to rotate the impeller about the center axis; and   a housing arranged to accommodate the impeller.