Patent ID: 8225623
Filing Date: 2012-07-24
Classification: F04D,F24F

Abstract:
1. A centrifugal fan comprising: a main plate having a flat portion formed on the outer circumferential side and a convex boss formed at the center for serving as a fixing part of a rotation shaft of a motor; a side plate, having an air guide wall, provided to surround around the boss with a predetermined space therebetween; and a plurality of blades provided between the main plate and the side plate substantially perpendicularly to a plane orthogonal to the rotation axis of the fan, wherein due to rotation of the plurality of blades, air is sent from a suction port formed between the wall of the main plate on the side of the boss and an end portion of the side plate opposing the wall on the side of the boss, toward a blow-out port formed between an external circumferential side flat portion of the main plate and an end portion of the side plate opposing the external circumferential side flat portion, and wherein when a blade edge positioned on the downstream side of the blowing direction is designated as a blade rear-edge, the centrifugal fan has a relationship of the outer diameter of the side plate>the outer diameter of the blade rear-edge on the side of the side plate>the outer diameter of the blade rear-edge on the side of the main plate≧the outer diameter of the main plate, and the blade rear-edge is located inside of a straight line connecting a connection point between the blade rear-edge and the main plate to a connection point between the blade rear-edge and the side plate relative to a rotation axis, and the distance between the blade rear edge and the rotation axis increases toward the side plate from the main plate.