Centrifugal fan and fan with sound-muffling box having the centrifugal fan built-in

摘要

A centrifugal fan includes a casing side plate with a casing inlet, a spiral scroll, a tongue, a casing outlet, a main plate, a retaining ring, multiple blades arranged between the main plate and the retaining ring, and an air-intake space surrounded by the blades. The centrifugal fan further includes an airflow accelerator in the air-intake space for increasing an airflow speed of a gas toward the blades.

主权项

1. A centrifugal fan in which an impeller is disposed inside a fan casing,
the fan casing including a casing side plate with a casing inlet for taking in a gas, a spiral scroll, a tongue, and a casing outlet, and the impeller including a main plate fixed to a rotating shaft that transmits rotation of a motor, a retaining ring disposed facing the main plate, and a plurality of blades arranged between the main plate and the retaining ring, wherein the centrifugal fan takes in the gas from the casing inlet, passes the gas through an air-intake space surrounded by the blades and between the blades, and discharges the gas from the casing outlet by rotating the impeller, the centrifugal fan further includes an airflow accelerator in the air-intake space for increasing an airflow speed of the gas toward the blades, the airflow accelerator is a thin plate including a first side whose length is shorter than a distance from the main plate to the retaining ring, a second side whose length is shorter than a distance from a circumferential plane extending from a radially outermost periphery of the motor to the blades, and a third side perpendicular to the first side and the second side, a line aligned with the second side of the airflow accelerator and projecting from an end of the airflow accelerator intersects a face formed by the casing outlet at a substantially orthogonal angle, and the face is a plane connecting outlet ends of the tongue and the scroll at the casing outlet.