Patent ID: 6034451
Filing Date: 2000-03-07
Classification: F04D

Abstract:
A centrifugal fan comprising:a casing having an outer wall and a central region;an electric motor in said central region of the casing;a fan rotor in said central region of the casing, said rotor being coupled to the motor to be driven by the motor and having a peripheral portion, the outer wall of the casing and the peripheral portion of the fan rotor together defining a volute within the casing for channeling air delivered by the fan rotor in a direction tangential to the peripheral portion of the fan rotor, the volute having an inlet end and a minimum cross section at said inlet end, wherein said outer casing wall defining the volute defines a first predetermined lateral zone and through apertures, constituting diversion ports, formed in the first zone to selected dimensions, for taking off some of the air delivered by the fan rotor, the first zone being close to the inlet end of the volute, the casing defining a predetermined second zone in said central region, the fan further including a diversion duct outside the casing, the diversion duct having a first end fixed to the casing and in communication with the diversion ports, for receiving air delivered through the diversion ports, and a second end fixed to the casing and open in said second zone, wherein air, diverted from the volute through the diversion ports and the diversion duct to the central region of the casing, cools the motor.