Patent ID: 9702373
Date: 2017-07-11
CPC Classifications: F04D

Claim:
1. A single suction centrifugal fan comprising: a motor; a casing having a spiral shape; and an impeller housed in the casing, the impeller having a plurality of blades, an impeller main plate and an auxiliary ring to which the blades are fixed, the casing including a suction side plate having a suction port, and a motor fixing side plate to which the motor is fixed, the impeller main plate having a center portion fixed to the motor, wherein both of the impeller main plate and an auxiliary ring are planar, the impeller main plate has a main plate opening formed between the blades and the center portion of the impeller main plate, a constriction portion is formed between the main plate and the motor fixing side plate by projecting a portion of the motor fixing side plate towards the main plate, in a region between the outer side of the main plate opening and the inner side of the blades, the constriction portion projects in a direction of a blade end portion imaginary plane, the constriction portion being closer to the blade end portion imaginary plane than an end of the motor except the motor shaft, and a distance between the motor fixing side plate and a blade end portion imaginary plane is narrower at the constriction portion than a distance between the blade end portion imaginary plane and the motor fixing side plate where the constriction portion is not formed, where the blade end portion imaginary plane is defined as 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.