Control for variable output centrifugal fan - is provided by slots in intake cone with a ring movable encompassing the taper part

摘要

Centrifugal fan impeller (2) is mounted on a shaft (3) and is contained within a volute housing (1). Air enters the casing into the eye of the impeller through an inlet duct (7) which passes through the end (6) of the casing and has a taper section inside the casing (1) towards the eye of the impeller. This taper section is equipped with a row of slanting slots (8) round its periphery. A ring (9) runs round the taper over the holes and can be moved circumferentially. It has similar slots (10) in it so that as it is moved it opens or closes the slots in the taper piece. The recirculation permitted by the opening of the slots varies the output of the fan.