Centrifugal fan

Abstract

A centrifugal fan includes a centrifugal impeller rotatable around an axis of rotation; a drive motor of the centrifugal impeller; a casing including a central portion for housing the motor and the centrifugal impeller and a tangential outlet channel in communication with the central portion. The casing has an inlet opening in the central portion and an outlet opening in the tangential outlet channel. The fan includes a system for cooling the motor including the impeller, a ventilation channel operating between the tangential outlet channel and the central portion for generating a flow of cooling air, a collar integral with the centrifugal impeller extending axially from the centrifugal impeller around the motor and a plurality of blades of the motor for generating a tangential cooling component which combines with the flow of cooling air and generating as a resultant, a helical vortex around the motor.

1 . A centrifugal fan comprising
 a centrifugal impeller rotatable around an axis of rotation;   a drive motor of the centrifugal impeller;   a casing comprising a central portion for housing the motor and the centrifugal impeller and a tangential outlet channel in communication with the central portion, the casing having an inlet opening in the central portion and an outlet opening in the tangential outlet channel,   a system for cooling the motor comprising the impeller and a ventilation channel operating between the tangential outlet channel and the central portion for generating a flow of cooling air, the fan characterised in that the cooling system comprises a collar integral with the centrifugal impeller extending axially from the centrifugal impeller around the motor and a plurality of radial blades supported by the collar and facing the motor for generating a tangential cooling component which combines with the flow of cooling air generating as a resultant a helical vortex RF around the motor.   
     
     
         2 . The fan according to  claim 1 , wherein the casing comprises a cover closing the central portion positioned coaxially to the motor on the opposite side with respect to the centrifugal impeller, the ventilation channel being at least partly formed between the outer surface of the collar and the cover. 
     
     
         3 . The fan according to  claim 2 , wherein the ventilation channel has an annular outlet, delimited between the cover and the centrifugal impeller, having dimension of the same order of magnitude as the dimension of the ventilation channel between the collar and the cover. 
     
     
         4 . The fan according to  claim 1 , wherein the cooling system comprises a plurality of centrifugal blades extending from the opposite side of the motor with respect to the collar, for forcing the cooling flow along the tangential outlet channel. 
     
     
         5 . The fan according to  claim 4 , wherein the centrifugal blades extend from the collar and form a single body with the collar. 
     
     
         6 . The fan according to  claim 1 , wherein the collar and the first radial blades are made in a single body with the centrifugal impeller. 
     
     
         7 . The fan according to  claim 1 , wherein the motor is at least partly inserted in the centrifugal impeller. 
     
     
         8 . The fan according to  claim 1 , wherein the casing comprises a cover closing the central portion positioned coaxially to the motor on the opposite side with respect to the centrifugal impeller, the cover having a cylindrical inner side wall and an inner rear wall delimiting a housing in which the motor is inserted, the ventilation channel being formed between the collar and the cylindrical inner side wall, an air circulation zone being formed between the inner rear wall and a rear surface of the motor, the ventilation channel and the circulation zone being in fluid communication with each other. 
     
     
         9 . The fan according to  claim 1 , wherein the ventilation channel is formed by a recirculation duct outside the casing having inlet in the tangential outlet channel and outlet in the central portion.