Patent ID: 7281897

Claim:
A multi-blade centrifugal blower comprising: an impeller wheel which is rotatable with respect to a rotation shaft thereof, the impeller wheel having a plurality of blades which are arranged around the rotation shaft, a side plate which is connected with each of the blades at a side of one rotation-shaft-direction end of the blade, and a main plate which is connected with each of the blades at a side of an other rotation-shaft-direction end of the blade, the main plate being integrated with the rotation shaft; and a casing for accommodating the impeller wheel, wherein: when the impeller wheel is rotated, air is sucked through a suction portion formed at the side of the one rotation-shaft-direction end and is blown toward a diameter-direction outer side of the impeller wheel; an inside periphery of the blade has a taper portion which is arranged at least at the side of the one rotation-shaft-direction end, the taper portion tapering from the side of the other rotation-shaft-direction end toward the side of the one rotation-shaft-direction end; in a rotation-shaft-direction cross section of each blade, the taper portion is positioned at a front side of a rotation direction R of the impeller wheel with respect to a back portion which is disposed at the side of the other rotation-shaft-direction end of the blade; and each of inlet angles throughout the taper portion has a value in a predetermined range, the inlet angles being respectively at cross sections of the blade which are perpendicular to the inside periphery of the blade in a meridional plane.