Patent ID: 9011092
Filing Date: 2015-04-21
Classification: F04D,F05D

Abstract:
1. A multi-blade centrifugal fan comprising: an impeller having numerous blades and provided in a freely rotatable manner in a scroll casing formed in a spiral shape with a tongue portion serving as its starting point, wherein the scroll casing is provided with an axially expanded portion that forms an air channel that is expanded in a rotation axis direction at a radially outer side of an annular flange portion that supports the impeller at the bottom surface of the scroll casing; and in a region of an outlet between the tongue portion and a spiral-end portion of the scroll casing in the axially expanded portion, a protrusion that protrudes radially outward from a radially inner side surface by a predetermined amount in a radial direction so as to directly face an airflow in a circumferential direction is provided.