Patent ID: 6837680

Claim:
A centrifugal blower comprising: a centrifugal fan that has a plurality of blades, which are generally arranged along a circle, wherein the centrifugal fan axially draws air and radially blows the drawn air; a motor that rotates the centrifugal fan; and a scroll casing that surrounds the centrifugal fan and includes: an air inlet that is arranged adjacent to one axial end of the centrifugal fan to supply air to the centrifugal fan; and a scroll air passage that extends around the centrifugal fan along an inner surface of a peripheral wall of the scroll casing, wherein: a nose, which is formed in the inner surface of the peripheral wall and projects in a circumferential direction opposite to a rotational direction of the centrifugal fan, forms an initial point of the scroll air passage; the inner surface of the peripheral wall includes an initial section, which extends from a circumferentially projected end of the nose, wherein the initial section of the inner surface includes: a first surface part that receives and guides a first airflow component of airflow that is radially blown by a corresponding one of the blades, wherein the first airflow component has a first velocity; and a second surface part that receives and guides a second airflow component of the airflow that is radially blown by the corresponding one of the blades, wherein the second airflow component has a second velocity that is smaller than the first velocity; the first surface part and the second surface part at least partially overlap with each other in a direction generally parallel to a rotational axis of the centrifugal fan; and the first surface part is radially closer to the blades in comparison to the second surface part.