초록 ▼

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 verti

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.

대표청구항 ▼

The invention claimed is: 1. An improved axial fan for exhausting humid, corrosive and dusty air, the improvements comprising: a) a housing enclosure having an inner cavity defining an air flow passageway having large radii corners and having a first opening of square section with a shutter assembl

The invention claimed is: 1. An improved axial fan for exhausting humid, corrosive and dusty air, the improvements comprising: a) a housing enclosure having an inner cavity defining an air flow passageway having large radii corners and having a first opening of square section with a shutter assembly comprising a frame on which are pivotally mounted a plurality of vanes including a central vane, for closing or opening said first opening, each of said vanes being pivotally interconnected, with crank rods and at least one tie rod, said frame further comprising an operative extension spring with one end connected to said frame and the other end connected to said tie rod for urging, upon fan operation, the shutter vanes toward a full wide open position, b) an axially spaced second opening of round section including a safety guard, c) a streamlined central structural member, axially spaced between said openings, connecting two opposite sides of said housing enclosure and comprising a pair of airfoil wings for guiding efficiently the air flow, d) a drive motor that is either electric or hydraulic mounted on a rigid base secured to said central structural member, e) a propeller-pulley assembly secured at one end of a rotating shaft fitted into a pair of pillow block bearings bolted to said central structural member for rotatably holding said propeller-pulley assembly comprising a plurality of airfoil blades extending radially outwardly from said propeller-pulley assembly and rotating with said propeller-pulley assembly, said propeller pulley assembly being located opposite to said shutter assembly, f) a venturi built with said fan housing enclosure, substantially entirely surrounding at close distance the blade tips of the propeller, g) a centrifugal shutter mechanism, connected at one end of said rotating shaft of said fan, for moving the shutter from a closed position, when the fan is disabled, to a normally open position when the fan is enabled, and comprising a hermetic housing assembly, said housing being made up of a pair of matching molded shells comprising a pair of oppositely radially extending cavities, each cavity including a pair of movable masses equally spaced apart relative to the fan rotational axis and operatively connected to an axially sliding reciprocating actuator via a pair of arms pivotally attached to said hermetic housing, said arms being operatively connected at corresponding ends respectively to the axially sliding actuator located into an axially extending cavity of said hermetic housing coaxially to said fan axis of rotation and positioned adjacent to said central vane of said shutter assembly, said axial sliding actuator further comprising an internal operative spring and an operative end located in proximity to the shutter central vane, said actuator being movable between an outward position frictionally engaging a convex shaped cam secured to said central vane of said shutter to rotate and shut said shutter central vane and the other vanes by the biasing force of said internal spring and an inward position away from said central vane of said shutter for causing the opening of said shutter in response to the rotation of said propeller, said opening and closing controlled by the minimum speed of operation of the fan. 2. The fan as claimed in claim 1, wherein said plurality of radial airfoil blades comprise radially extending adjustable flexible means mounted at the tips of each blade for adjusting the tip blade clearance with said venturi of said fan housing, said improved housing including a rigid roll-formed ring located adjacent to said blade tips. 3. The fan as claimed in claim 2, wherein said adjustable flexible means are made of soft rubber adapted to minimize the clearance between the venturi and blade tips for preventing air from flowing back around the blade tips for increased performance of said fan, enabling said fan to work efficiently at higher static pressure with reduced air vortices, vibrations and noise. 4. The fan as claimed in claim 1, wherein said square frame of said shutter assembly includes longitudinally extending cavities and comprises plastic rods on which are pivotally received said vanes of said shutter, said frame assembly being adapted to be mounted selectively either horizontally or vertically across said inlet opening of said fan housing. 5. The fan as claimed in claim 1, each of said arms being movably connected at corresponding ends with said axial sliding actuator for transferring radial movements of said centrifugal masses, upon fan rotation, to axial movements of said axial actuator, so that said centrifugal masses and said arms will swing in unison during any axial stroke of the axially sliding actuator.