Axial flow fan improvements

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.

1 - 18 . (canceled)  
   
   
       19 . A fan for use in ventilation of a building comprising: 
 a housing and said housing having an interior passageway extending along an axis in an axial direction between an air intake end and a spaced apart air discharge end;    a bracket supporting a fan assembly and said bracket being supported by four intersecting arms fixed to four opposite sides of said fan housing intake end;    each of said arms extending radially toward a central locus having a rigid case and said case having bearing means and means for connecting said arms thereto;    a shaft rotatably journaled into said bearing means;    a drive motor having a drive toothed pulley transmitting power to a propeller and said propeller having a plurality of airfoil shaped blades radially extending outwardly from said shaft toward tips portion thereof; said blades further having guiding fins members formed on a front face thereof;    a bell shaped intake mounted at said air intake end;    an outlet cone mounted at said discharge end;    a shutter assembly having a pair of shutter hinged doors diametrically extending across said output end;    said doors being connected with a pair of gears for unison movements in opposite direction and comprised of a master door having a convex shaped cam mounted near the middle thereof, and;    slave doors disposed next to one another having their leading edges journaled on top and bottom bearings to rotate said slave doors toward said discharge cone.    
   
   
       20 . The fan as in  claim 19 , wherein said propeller comprises a plurality of airfoil shaped blades; 
 each of said aifoil shaped blades comprising at least a pair of guiding fins members formed on a front face thereof wherein said blades tips portion comprise a radially adjustable shoe having an air flow guiding fin extending circumferentially to fully encircle said tip portion of said blades for preventing air flow returns upstream from said propeller blades and for preventing turbulent flow around said blade tips.    
   
   
       21 . The fan as in  claim 19 , wherein a 12″ deep bell shaped intake is mounted at said intake end of said fan housing and a discharge cone at said output end thereof.  
   
   
       22 . The fan as in  claim 19 , wherein said shutter doors are one-piece construction made of rigid, non-corrosive material and comprise an internal cavity with insulation material to prevent conduction heat losses and further comprising an outer portion surface adapted to contact and press seal means mounted at said discharge end of said fan housing, wherein said seal means are compressed by biasing means associated to a centrifugal device to prevent convection heat losses  
   
   
       23 . The fan as in  claim 19 , wherein said fan assembly has a centrifugal shutter mechanism mounted at one end of said rotating shaft wherein said centrifugal mechanism has at least a pair of short and long links pivotally connected to each other, at least a pair of centrifugal masses equally spaced apart relative to said fan rotational axis, secured to said long links operatively connected to a reciprocating actuator mounted on a guiding hollow shaft coaxially with said fan rotational axis adjacent said master door comprising a convex shaped cam mounted thereon, said axial sliding actuator further comprising an internal operative compression biasing means and an operative end located proximal of said master door convex shaped cam said actuator being movable between an outwardly position frictionally engaging said convex shaped cam to rotate and shut said master door and said slave door so that said doors are biased against seal means to prevent the passage of air through said fan outlet housing and an inwardly position away from said master door for causing the fully opening of said doors in response to the rotation of said propeller.  
   
   
       24 . A fan as in  claim 23  wherein said centrifugal mechanism has an axially slidable actuator having an operative end including a ball thrust bearing interposed between said operative end and said shutter hinged doors for rotatably connecting said doors for pushing or pulling them from a first position wherein said shutter assembly closes off the air passageway to a second position wherein air is permitted to flow throughout said fan housing.  
   
   
       25 . A fan for use in a building for ventilation comprising: 
 a box type housing with an interior cavity extending along an axis, an air intake end, a spaced apart air output end, a bracket having four arms fixed at each respective ends to four opposite sides across said housing air intake end, wherein said arms extends inwardly to a central locus having a bearing case comprised of four lugs projecting outwardly therefrom and connecting said four arms;    said bearing case having bearing means and a hollow fan shaft rotatably journaled into said bearing means;    a drive motor with a drive toothed pulley for transmitting power via a toothed belt to a propeller pulley secured to said fan hollow shaft;    a propeller comprising a central split hub and a plurality of airfoil shaped blades including a pair of guiding fin members formed on a front face of said propeller blades;    said blades comprising a rigid stem journaled into said split hub which is secured to on one end of said fan hollow shaft;    said propeller having blades extending radially outwardly from said central split hub and rotatably therewith, wherein said propeller blades comprises means for assisting in keeping the air flow with a minimum of vortices so as to reduce the turbulence in the air flow through the fan passageway and prevent vibrations, noise and wear of associated shutters positioned down stream or upstream at close distance from said propeller.    
   
   
       26 . The fan as in  claim 25  wherein said propeller blade means comprise a plurality of fins positioned at a distance from said rotation axis of said propeller and wherein each propeller blade being entirely surrounded by an outer band comprising a small bell mouth having a flanged inlet end, extending radially, positioned adjacent an orifice plate fixed to said fan housing such as to form a small radial clearance to restrict the flow of air exited from said fan therefore for preventing backflow from downstream to upstream of said ducted propeller.  
   
   
       27 . The fan as in  claim 25 , further comprising a shutter assembly mounted therein said fan housing across said input air intake or across said air output of said housing, wherein said shutter assembly comprises a plurality of hinged vanes adapted to be mounted vertically or horizontally across said inlet or outlet of said fan housing, preventing, when they are mounted vertically dust accumulation thereon, wherein each pair of vanes leading edges are pivotally connected with a continuous hinge such that each pair of vane is more rigid preventing vibrations thereof.  
   
   
       28 . The fan as in  claim 27  wherein said vanes are made of extruded aluminium or plastic comprising cavities filled with insulating material and a longitudinal extending gear to synchronize said vanes so as to simultaneously dose or open said vanes.  
   
   
       29 . The fan as in  claim 26  wherein said vanes of said shutter assembly being operatively connected to a centrifugal mechanism connected for rotation to said propeller rotating shaft, wherein said centrifugal mechanism includes at least a pair of links pivotally connected to each other and comprising centrifugal masses equally spaced apart relative to said fan rotational axis, operatively connected to an axially sliding reciprocating actuator mounted on a guiding hollow shaft coaxially with said fan axis of rotation, positioned adjacent to said shutter assembly, said axial sliding actuator further comprising an internal compression biasing means and an operative end comprising a push/pull actuator rod secured to a bearing case comprising a ball bearing, said operative actuator rod being movable between an outwardly position to rotate and shut said vanes by the biasing force of said internal compression biasing means to firmly close said vanes and prevent the passage of air through said fan housing and an inwardly position away from said shutter assembly for causing the fill opening of said vanes in response to the rotation of said propeller.  
   
   
       30 . A fan for use in a building for ventilation, comprising: 
 a housing having a square or round intake end with an interior cavity extending along an axis, a spaced apart round air output end, a bracket having four arms fixed at each respective ends to four opposite sides across said housing air intake end, wherein said arms extend inwardly to a central locus having a bearing case having four lugs projecting outwardly therefrom and connecting said four arms;    said bearing case comprising bearing means and a fan hollow shaft rotatably journaled into said bearing means;    a drive motor with a drive toothed pulley for transmitting power via a toothed belt to a propeller pulley secured to said fan hollow shaft;    a propeller comprising a central split hub and a plurality of blades including a rigid stem for rotatably journaling them into said split hub secured on one end of said hollow fan shaft;    said propeller having blades extending radially outwardly from said central split hub and rotatably therewith, wherein said propeller blades comprises means for assisting in keeping the air flow with a minimum of vortices so to prevent vibrations, noise and wear of an associated shutters positioned downstream or upstream at close distance with said propeller wherein said shutter comprises a plurality of hinged vanes angularly spaced working in tandem wherein each vane comprise a leading edge rotating around a common round stationary shaft secured at both ends to said flanged output end of said fan housing and to a central rim supporting said shafts and said vanes wherein said vanes are pivoting between a fully open configuration in which said output opening is open to a closed configuration closing said output opening against seal means.    
   
   
       31 . The fan as in  claim 30  wherein said angularly even spaced vanes are open and aligned to the air flow and maintained positively open by centrifugal action of a centrifugal actuator wherein said straight vanes positioned adjacent said propeller assist to control the residual swirl of the air exiting said propeller providing a more efficient fan and less noisy fan.  
   
   
       32 . The fan as in  claim 31  wherein said vanes are insulated vanes and wherein said leading edge of said vane is continuously connected with said leading edge of said adjacent vane.  
   
   
       33 . The fan as in  claim 32  wherein said pair of vanes when open take the shape of a single aerodynamic shaped vane having a NACA profile such as to cause a decrease of noise and a decrease of drag of said vanes.