Abstract: An energy efficient and compact axial fan with a housing comprising a fan assembly comprising a drive motor and a propeller coupled thereto. The inlet opening and/or the outlet opening of the fan housing are provided with a shutter assembly positioned adjacent the propeller and having a plurality aerodynamically shaped pivoted louvers working in tandem for less air obstruction and noise. The propeller comprises a plurality of radial blades comprising means for straitening the air flow and reducing the vortex flow of the propeller thereby permitting the shutter to be mounted adjacent the propeller to lessen the dept of the fan housing for making the fan more compact.

Abstract: An efficient axial fan has a housing enclosure with a square inlet opening and a round outlet opening, a fan assembly with a drive motor and a propeller secured to a shaft and coupled thereto. The entrance of the fan housing is provided with a shutter assembly which is disposed horizontally or vertically across the square inlet opening and comprises a plurality of vanes including a central vane operated by a centrifugal shutter mechanism secured to one end of the propeller shaft, opposite to the propeller and adjacent to the central vane of the shutter assembly. The centrifugal shutter mechanism is normally provided with a hermetic housing comprising a pair of radial masses operatively connected via a pair of pivoting arms to an axial sliding reciprocating actuator which is disposed adjacent to the shutter central vane.

Abstract: An efficient axial fan has housing with a square inlet opening and a round outlet opening, a fan assembly with a drive motor and a propeller coupled thereto. The entrance of the housing is provided with a shutter assembly disposed horizontally or vertically across the entrance of the fan and comprising a plurality of vanes including a central operative vane operated by a centrifugal shutter mechanism secured to one end of the propeller shaft, opposite to the propeller and adjacent to the operative central vane of the shutter assembly. The centrifugal shutter mechanism is normally provided with a hermetic housing comprising a pair of radial masses operatively connected by means of a pair of pivoting arms to an axial sliding reciprocating actuator which is disposed adjacent to the shutter central operative vane.

Abstract: A fan has an associated centrifugal mechanism and a shutter, comprising a plurality of pivoted vanes and a central vane pivotally interconnected with a pair of heavy tie rods. The centrifugal mechanism is driven by the fan propeller and comprises a hermetic housing wherein are located, symmetrical spaced apart in rapport to the fan axis, at least a pair of radial sliding masses operatively connected with flexible cables to an axial sliding reciprocating actuator which is disposed at proximity of the shutter central vane. When the fan starts to operate in either direction by an electric motor, the radial masses slide radially by centrifugal action and pull the axial reciprocating actuator away from the central vane, allowing the shutter heavy tie rods, to open the shutter. When the fan stops, an internal spring housed within the axial sliding reciprocating actuator pushes it against the central vane causing the closing of the shutter.