Single suction type centrifugal fan

Abstract

A single suction type centrifugal includes: a casing having a spiral shape; and an impeller housed in the casing and provided with a plurality of blades and an impeller main plate to which the blades are fixed. The casing includes a suction side plate having a suction port, and a motor fixing side plate to which a motor is fixed. A center portion of the impeller main plate is fixed to the motor, and a main plate opening is formed in the impeller main plate between the blades and a center portion of the impeller main plate. A plane which passes end portions of the blades on a motor fixing side plate side and is perpendicular to a rotary shaft of the motor is assumed as a blade end portion imaginary plane. A constriction portion is formed where a distance between the blade end portion imaginary plane and the motor fixing side plate is narrowed between the main plate opening and the blades.

Dependencies are inferred from the claim text.