Patent attributes
An impeller includes a hub rotated about an up-down axis and inclined blades disposed circumferentially on a hub's outer circumferential surface. The outer circumferential surface includes a first surface including a portion axially overlapping the blade above its joined portion to the blade, a second surface including a portion axially overlapping the blade below the joined portion, and a connecting portion connecting a rotating-direction rear end of the first outer circumferential surface and a rotating-direction front end of the second outer circumferential surface. The connecting portion is arranged forward of a rotating-direction blade front edge. A distance from the axis to a first point, positioned at the rotating-direction rear end of the first outer circumferential surface, is not shorter than that from the axis to a second point, positioned at the rotating-direction front end of the second outer circumferential surface and at the same axial position as the first point.
