CENTRIFUGAL BLOWER AND VENTILATION FAN

摘要

A centrifugal blower is provided with: an impeller (2) rotationally driven by a drive motor (3); a scroll casing (4) provided with a suction opening surface (10) having an opening (9), the scroll casing (4) being further provided with a wall (12), the distance of which from an axis serving as the rotation center of the impeller (2) varies depending on the position of the wall (12), the scroll casing (4) redirecting the air flow in the centrifugal direction, which is generated by the rotation of the impeller (2), to one direction; an air intake section (13) provided with a bell mouth section (18) having a large-diameter-side end (16) located further toward the upstream side of the flow of sucked-in air than the suction opening surface (10); and a protrusion section (15) extending from the air intake section (13) in the direction perpendicular to the axis as the rotation center of the impeller (2) and away from the rotation center and surrounding a part of the bell mouth section (18).