Patent ID: 7972110

Claim:
A centrifugal blower comprising: a fan including a blade, the fan rotating around a rotation axis; and a scroll casing housing the fan, wherein the scroll casing has a first axial wall portion, a second axial wall portion, and a side wall extending between the first and second axial wall portions, the scroll casing including a suction port in the first axial wall portion, the scroll casing also defining a nose portion and a scroll finish portion, such that the fan sucks a fluid through the suction port and pushes the fluid from the nose portion and out of the scroll casing from the scroll finish portion, wherein: the scroll casing has scroll radii that are measured transverse to the rotation axis and that vary according to a position from the nose portion to the scroll finish portion, a maximum radius of the scroll radii is closer to the second axial wall portion than the first axial wall portion, a minimum radius of the scroll radii is closer to the first axial wall portion than the second axial wall portion, the side wall has a first side wall portion extending from the first axial wall portion to an intermediate portion of the side wall and a second side wall portion extending from the second axial wall portion to the intermediate portion in the nose portion, the maximum radius is greater than the minimum radius at the nose portion, the second side wall portion extends outward in a radial direction of the scroll casing more than the first side wall portion, and the maximum radius of the scroll radii at the nose portion is in a range of from approximately 0.7 to approximately 1.0 times an outer diameter of the fan.