Centrifugal fan

Abstract

A centrifugal fan has an impeller and a bell mouth. The bell mouth has a plurality of wall parts provided on an outer peripheral surface of the bell mouth. The wall parts are arranged at predetermined intervals on the outer peripheral surface in a circumferential direction of the outer peripheral surface. Each of the wall parts extends along the outer peripheral surface from the front side to the rear side in an axial direction so as to be substantially parallel to the axial direction and to a radial direction of the bell mouth.

1 . A centrifugal fan, comprising:
 an impeller, which includes a hub that is fixed to a rotating shaft of a fan motor, a shroud that has an air suction port opened in a circular shape around a central axis of the rotating shaft and is disposed to face the hub on a front side in an axial direction of the rotating shaft, and a plurality of blades that are arranged between the hub and the shroud along a circumferential direction of the air suction port; and   a bell mouth, which is disposed to face the shroud on the front side in the axial direction and which has a part, on a rear side, inserted into the shroud through the air suction port while a predetermined gap is kept between the part and a peripheral rim part of the air suction port, and moreover which guides air suctioned from the front side to the rear side in the axial direction, to the air suction port of the shroud, wherein   the bell mouth has a plurality of wall parts provided on an outer peripheral surface of the bell mouth, the wall parts are arranged at predetermined intervals on the outer peripheral surface in a circumferential direction of the outer peripheral surface, and   each of the wall parts extends along the outer peripheral surface from the front side to the rear side in the axial direction so as to be substantially parallel to the axial direction and to a radial direction of the bell mouth.   
     
     
         2 . The centrifugal fan according to  claim 1 , wherein a height of an end part on the front side of each wall part with respect to the outer peripheral surface is greater than a height of an end part on the rear side of each wall part with respect to the outer peripheral surface. 
     
     
         3 . The centrifugal fan according to  claim 2 , wherein a height of each wall with respect to the outer peripheral surface increases gradually from the end part on the rear side toward the end part on the front side. 
     
     
         4 . The centrifugal fan according to  claim 1 , wherein
 the end part on the rear side of each wall part is an inclined surface in which the height thereof with respect to the outer peripheral surface decreases gradually from the front side toward the rear side, and   the peripheral rim part of the air suction port is an inclined surface facing the inclined surface of each wall part.