CA2512550C - Cooling fan with reinforced blade - Google Patents

Cooling fan with reinforced blade Download PDF

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Publication number
CA2512550C
CA2512550C CA002512550A CA2512550A CA2512550C CA 2512550 C CA2512550 C CA 2512550C CA 002512550 A CA002512550 A CA 002512550A CA 2512550 A CA2512550 A CA 2512550A CA 2512550 C CA2512550 C CA 2512550C
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Canada
Prior art keywords
trailing edge
fan
fan blade
fan assembly
curved wall
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
CA002512550A
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French (fr)
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CA2512550A1 (en
Inventor
Walter Boyd
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Delta T Corp
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Delta T Corp
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Publication date
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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04DNON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00Details, component parts, or accessories
    • F04D29/26Rotors specially for elastic fluids
    • F04D29/32Rotors specially for elastic fluids for axial flow pumps
    • F04D29/38Blades
    • F04D29/388Blades characterised by construction
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04DNON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00Details, component parts, or accessories
    • F04D29/26Rotors specially for elastic fluids
    • F04D29/32Rotors specially for elastic fluids for axial flow pumps
    • F04D29/38Blades
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01DNON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D5/00Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
    • F01D5/12Blades
    • F01D5/14Form or construction
    • F01D5/147Construction, i.e. structural features, e.g. of weight-saving hollow blades
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04DNON-POSITIVE-DISPLACEMENT PUMPS
    • F04D25/00Pumping installations or systems
    • F04D25/02Units comprising pumps and their driving means
    • F04D25/08Units comprising pumps and their driving means the working fluid being air, e.g. for ventilation
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04DNON-POSITIVE-DISPLACEMENT PUMPS
    • F04D25/00Pumping installations or systems
    • F04D25/02Units comprising pumps and their driving means
    • F04D25/08Units comprising pumps and their driving means the working fluid being air, e.g. for ventilation
    • F04D25/088Ceiling fans
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02TCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T50/00Aeronautics or air transport
    • Y02T50/60Efficient propulsion technologies, e.g. for aircraft

Abstract

A circulator device comprising a large diameter fan having reinforced fan blades with a tapered airfoil shape is disclosed. The fan blades may be formed using an extrusion method of fabrication, wherein each fan blade (316) may comprise a reinforced trailing edge (514) with a downwardly extending flange.
The benefit of forming each fan blade with a reinforced trailing edge (514) of the present invention results in improved structural characteristics such that the trailing edge of each fan blade (316) may be fabricated longer so as to improve aerodynamic performance. Also, the reinforced trailing edge resists tearing that my occur during extrusion by adding the bent flanged region to at least one distal end of the trailing edge. For example, the bent portion (538) of the trailing edge tends to rigidly orient the extruded material in a stabilized position more readily during formation.

Description

COOLING FAN WITH REINFORCED BLADE

Background of the Invention Field of the Invention The present invention relates to circulatory devices in large buildings and, in particular, concerns a cooling fan having reinforced blades that may be used to circulate a large volume of air.

Descrintion of the Related Art People who worlc in large buildings, such as warehouses and aiiport hangers, are routinely exposed to working conditions that range from being uncomfortable to hazardous. On a hot day, the inside air temperature may reach a point where a person is iuiable to maintain a healthy body temperature. Moreover, many activities that occur in these environments, such as welding or operating internal combustion engines, create airboizie contaminants that may be deleterious to those exposed. The effects of airborne contaminants are magnified to an even greater extent if the area is not properly vented.
The problem of cooling or circulating air in large buildings may not be solved by conventional air conditioning methods. The large volume of air within the building `20 in conjunction with the large rate of heat conducted througli ceilings and walls may require powerful air conditioning devices to be effective. If such devices were used, the operating costs would be substantial. Also, conventional air conditioning routinely re-circulates the internal air for added cooling efficiency. Therefore, conventional air conditioning is not typically used in ventilation systems that seive to rapidly remove airborne contaminants, such as exhaust or smoke, and replace the contaminated air with fresh air from an outside source. For example, when welding and operating internal combustion engines within a structure, the internal air must be replaced and should not be re-circulated due to an iulhealthy accumulation of airborne contaminants, In general, small and large diameter fans may be used to provide some degree of circulation, cooling, and ventilation when conventional air conditioning is not feasible.
A drawback of using small diameter fans to circulate air is that the resulting airflow 78348-23(S) dramatically tapers-off at downstream locations. Also, the large amount of electrical power required by the simultaneous use of these devices in great numbers negates their advantage as an inexpensive cooling system.
Moreover, a drawback to using large diameter fans is that they typically require specially constiucted high-strengtli light-weight blades that may withstand large stresses caused by significant gravitational torques that increase with an increasing blade length to width aspect ratio. The fact that the rotational inertia of the fan increases with the square of the diameter requires the use of high torque producing gear reduction mechanisms. Unfortunately, conventional drivetrain components may be susceptible to mechanical failure due to the substantially large torque produced by electric motors during their startupphase, which may decrease the reliability of large diameter fans.
Certain large diameter fans have been equipped witli low speed mechanisms and large fan blades witli aerodynamic features. For instance; U.S. Patent Number 6,244,821 discloses a low speed cooling fa.n having a large diameter with proportionally large fan blades that may be foimed using a generallylaioum extrusionprocess.
Uiifortunately, such extiuded blades have unsupported trailing edges that may tear froni defoiming or warping during formation and cooling. As a result, the aerodynamic features are shortened due to tearing created on longer iuisupported trailing edges during fabrication, which reduces the overall performance of the large fan blades. Therefore, the shortened trailing edges adversely impact the aerodynamic effectiveness of the large fan blades thereby potentially diminishing the efficiency of generated circulatoiy air flow within a stn.icture.
From the foregoing, there currently exists a need for a cost efficient circulatoiy device that provides optimal ventilation and effective cooling in large buildings. In particular, there currently exists a need for such a circulatory device that comprises improved fan blades and a method of manttfacturing the same so as to increase the stiuctural rigidity of the blade and maintain the enhanced aerodynamicperformance.
78348-23(S) Summary of the Invention In accordance with one aspect of the present invention, there is provided a fan assembly for circulating air in an industrial building, the fan assembly comprising:

a support adapted to allow the mounting of the fan assembly to the roof of the industrial building; a motor coupled to the support, the motor engaged with a rotatable shaft so as to induce rotation of the shaft; and a plurality of airfoil shaped fan blades attached to the rotatable shaft, wherein each fan blade is formed of an extruded material such that a first curved wall is joined to a second curved wall to form a leading junction and a trailing junction, and wherein the trailing junction extends to form a third curved wall having a tapered trailing edge, each blade further comprising a bent flange that distally extends from the trailing edge in a continuous manner that reinforces the trailing edge.

In accordance with a second aspect of the present invention, there is provided a metal fan blade for a fan assembly used in an industrial building, the fan blade comprising an extruded cross-sectional profile with a cross-sectional width of approximately 7 inches and having a plurality of curved walls, wherein a first curved wall is joined to a second curved wall to form an airfoil shape and the first curved wall is extended to form a tapered trailing edge wherein the distal end of the tapered trailing edge is bent to form a flanged portion extending outward from the direction of the trailing edge, wherein the flanged portion of the trailing edge downwardly extends from the lower surface of the trailing edge such that the angular displacement of the flanged portion from the lower surface of the trailing edge forms a reinforced region that increases the structural rigidity of the trailing edge so -2a-78348-23(S) that the flanged portion of the trailing edge resists damage, and wherein the flanged portion increases the volume of airflow resulting from the operation of the fan assembly having the fan blade.

In accordance with a third aspect of the present invention, there is provided a fan assembly for cooling industrial buildings, the fan assembly comprising: a mounting assembly having a rotatable hub that attaches the fan assembly to the ceiling of the industrial building; and a plurality of fan blades mounted to the rotatable hub, wherein each of the plurality of fan blades is at least 4 feet long and is formed of an extruded metal so as to have a first air foil section formed of a first curved wall, a leading edge and a tapered trailing edge, the tapered trailing edge extending outward from the rotatable hub, wherein the tapered trailing edge extends from the first curved wall of the fan blade and wherein the tapered trailing edge is bent at a distal end to integrally form a flange to reinforce the tapered trailing edge and so as to provide increased downward thrust during rotation of the fan blades.

In accordance with a fourth aspect of the present invention, there is provided a method of forming a fan blade comprising: softening a metal; forcing the metal into an extrusion die using an extrusion die using an extrusion press such that a cooled metal fan blade is extruded out of the extrusion die so as to have in uniform cross-section a first air foil section and a tapered trailing edge integrally attached to an end of the first air foil section and a reinforcing flange that extends outward from the direction of the tapered trailing edge so as to reinforce the tapered trailing edge during extrusion to inhibit tearing of the tapered trailing edge.
-2b-78348-23(S) In accordance with a fifth aspect of the present invention, there is provided a fan assembly for circulating air in an industrial building, the fan assembly comprising:
a support adapted to allow the mounting of the fan assembly to the roof of the industrial building; a motor coupled to the support, the motor engaged with a rotatable shaft so as to induce rotation of the shaft; and a plurality of fan blades attached to the rotatable shaft, wherein each fan blade is formed of an extruded metal such that a first curved wall is joined to a second curved wall to form a leading junction and a trailing junction, and wherein the trailing junction extends to form a third curved wall having a tapered shape that decreases in thickness across its length from approximately 0.1875 (3/16) inches at the trailing junction to approximately 0.0625 (1/16) inches at a trailing edge, each blade further comprising a flange that distally extends from the trailing edge in a continuous manner such that the angular displacement of the flange from the trailing edge forms a bent region that reinforces the trailing edge.

In accordance with a sixth aspect of the present invention, there is provided a metal fan blade for a fan assembly used in an industrial building, the fan blade comprising an extruded cross-sectional profile having a plurality of curved wall, wherein a first curved walls comprising a thickness of approximately 0.15625 (5/32) inches is joined to a second curved wall comprising a thickness of approximately 0.15625 (5/32) inches to form an airfoil shape having a trailing edge that includes a flange extending outward from the direction of the trailing edge, wherein the flanged portion of the trailing edge downwardly extends from the lower surface of the trailing edge such that the angular displacement of the flanged portion from -2c-78348-23(S) the lower surface of the trailing edge forms a reinforced region that increases the structural rigidity of the trailing edge so that the flanged trailing edge resists damage, and wherein the flange increases the volume of airflow resulting from the operation of the fan assembly having the fan blade.

The aforementioned needs may be satisfied by a fan assembly for circulating air in an industrial building. In one embodiment, the fan assembly may comprise a support adapted to allow the mounting of the fan assembly to the roof of the industrial building -2d-and a motor coupled to the support, the motor engaged with a rotatable shaft so as to induce rotation of the shaft. The fan assembly may further comprise a plurality of fan blades attached to the rotatable shaft, wherein each fan blade is formed of an extruded metal such that a first cuived wall is joined to a second curved wall to foi7n a leading junction and a trailing junction, and wherein the trailing junction extends to foim a third curved wall having a trailing edge, each blade further comprising a flange that distally extends from the trailing edge in a continuous manner such that the angular displacement of the flange from the trailing edge forms a bent region that reinforces the trailing edge. In one aspect, each fan blade comprises an airfoil shape having a tapered trailing edge that is bent to form the flange, wherein the flange downwardly extends from the lower surface of the third ctuved wall.
Additionally, the first cluved wall may bej oined to a second cuived wall to form a hollow interior region. The first cuived wall may be j oined to a second cuived wall to form a solid interior region. Also, the plurality of fan blades may be attached to a hub, which is coimected to the rotatable shaft. In one embodiment, the plurality of fan blades may comprise at least ten fan blades. It should be appreciated that the plurality of fan blades may comprise two or more fan blades without departing from the scope of the present invention. Each of the plurality of fan blades may be fabricated using an extrusion technique, wherein the extiuded metal comprises aluminum.
Moreover, each fan blade may comprise a cross-sectional width between approximately 5 inches and 8 inches. Each fan blade comprises a cross-sectional height between approximately 0.75 (3/4) inches and 1.50 (3/2) inches. Each fan blade comprises a length between approximately 4 feet and 14 feet. The first and second cwved walls comprise a thiclcness between approximately 0.0625 (1/16) inches and 0.1875 (3/16) inclies. The third curved wall comprises a tapered shape that decreases in thickness across its length from approximately 0.125 (1/8) inches at the trailing junction to approximately 0.0625 (1/16) inches at the trailing edge. The flange comprises a length between approximately 0.25 (1/4) and 0.375 (3/8) inches.
In another embodiment, the aforementioned needs may also be satisfied by a metal fan blade for a fan assembly used in an industrial building. In this particular embodiment, the fan blade may comprise an extruded cross-sectional profile having a plurality of curved walls, wherein a first ctuved wall is j oined to a second cutved wall to form an airfoil shape having a trailing edge that includes a flange extending outward from the direction of the trailing edge, wherein the flanged portion of the trailing edge downwardly extends from the lower surface of the trailing edge such that the angular displacement of the flanged portion from the lower surface of the trailing edge forms a reinforced region that increases the stntctural rigidity of the trailing edge so that the flanged trailing edge resists damage, and wherein the flange iucreases the vohune of airflow resulting from the operation of the fan assembly having the fan blade.
In still anotlier embodiment, the aforementioned may also be satisfied by a fan assembly for cooling industrial buildings. In this particular embodiment, the fau assembly may comprise a inounting asseinbly having a rotatable hub that attaches the fau assembly to the ceiling of the industrial building. The fan assembly may further comprise a plurality of fan blades mounted to the rotatable hub, wherein each of the plurality of fan blades is at least 3 feet long and is foimed of an extruded metal so as to have a first air foil section and a tapered trailing edge, wherein a flange is integrally formed at the end of the tapered trailing edge so as to reinforce the tapered trailiug edge and so as to provide increased downward thrust during rotation of the fan blades. In one aspect, the fan blades are foi7ned using an extrusion fabrication process, wlierein the flauge reinforces the tapered trailing edge during the extrusion fabrication process so that the tapered trailing edge resists tearing while being formed.
In yet another embodiment, the aforementioned needs may be satisfied by a method of foiming a fan blade. In this particular embodiment, the method may comprise softening a metal and forcing the inetal into an extrusion mold such that a cooled metal fan blade is extruded out of the extrusion mold so as to have in cross-section a first air foil section and a tapered trailing edge integrally attached to an end of the first air foil section and a reinforcing flange that extends outward from the direction of the tapered trailing edge so as to reinforce the tapered trailing edge during extrusion to inhibit teaiing of the tapered trailing edge. In one aspect, softening the metal may comprise softening ahuninum, wherein softening the metal may further comprise softening an alloyed aluminum with at least one of copper, manganese, silicon, magnesium, and zinc.
78348-23(S) Additionally, the method may still further comprise forming an extrusion die to produce the fan blade with a hollow interior, wherein forcing the metal into the extrusion die coinprises applying pressure to the softened metal using an extrusion press so as to force the softened metal through the extrusion die. Also, the j oined fan blades may be separated to fonn a plurality of individual fan blades.
In anotlier aspect, forcing the metal into the extrusion mold may produce at least one fan blade with a. unifoim cross-section, Moreover, forcing the metal into the extrusion mold may produce the at least one fan blade ha.ving a first surface and a second surface that combine to form the airfoil section, which enliances the cohnnnar propeities of the airflow prodttced by the at least one fan blade.
Furthermore, forcing the metal into the extrusion mold may produce the at least one fan blade with an extended first surface that comprises at least one of the tapered trailing edge and the reinforcing flange, which results in an improved airfoil design. These and other objects and advaitages of the present invention will become more apparent from the following descriptiontaken in conjunctionwitli the accompanyingdrawings.

Brief Description of the Drawin~s Figure 1 illustrates one embodiment of a fan assembly having a plurality of fan blades with each having a reinforced trailing edge that may be positioned adjacent to the ceiling of a large commercialbuilding.
Figiue 2 illustrates one embodiment of the airflow pattern generated by the fan assembly of Figtue 1.
Figure 3 ilhistra.tes a side elevation view of the fan assembly of Figure 1.
Figure 4 illustrates a.n axial view as seen by an observer looking up towards the fan assembly of Figure 1, Figure 5 illustrates a cross-sectional view of an individual fan blade in Figure 1, wherein the fan blade comprises a reinforced trailing edge.

Figure 5A illustrates a cross-sectional view of an individual fan blade having a solid interior region.

Figure 6 illustrates the cross-sectional view of the individual fan blade of Figure 5 including the aerodynamic forces generated by the fan assembly of Figure 1.
78348-23(S) Figure 7A illustrates one embodiment of a plurality of extn.ision based manufacturing components including an extnision die that may be used to form the extruded fan blade having the reinforced trailing edge.
Figure 7B illustrates one embodiment of an extrusion die that comprises ai opening with a pattern similar in shape to the cross-sectional profile of the fan blade having the reinforced trailing edge.

Detailed Descrintion of the Preferred Embodiment Reference will now be made to the drawings wherein like numerals refer to like parts througliout. Figure 1 illustrates one embodiment of a fan assembly 100 havinig a plurality of fa.n blades 316 with each having a reinforced trailing edge 514 that may be positioned adjacent to the ceiling 110 of a large commercial and/or industrial building 106. In a manner as will be described in greater detail herein below, an exti-usion process may be used to fonn each fan blade 316 witli the reiniforced trailing edge 514. In one . aspect, the occuirence of trailing edge tearing to the fan blade 3 16 during extrusion may be reduced due to the supporting features of the reinforced trailing edge 514 in a manner that will be described in greater detail herein below.
The fan assembly 100 may be attached to any suitable pre-existing siipporting structtue or to any suitable extension connected thereto in an overhead configuration such that the axis of rotation of the fan assembly 100 is along a substantially vertical direction.
It should be appreciated that the structural components of the fan assembly 100 iiicluding the scope aaid functionality of the reinforced trailing edge 114wil1 be described in greater detail herein below with reference to Figures 3-6, In one aspect, the fan assembly 100 may coinprise a low speed fan assembly as described in the Applicant's issued U.S. Patent Number 6,244,821., _ Figure 1 further illustrates the fan assembly 100 attached to an extension piece 101, which may be attached to a mounting location 104 positioned on the ceiling 110 using conventional fasteners, such as nuts, bolts, and/or welds, as is known in the a.t. A control box 102 may be connected to the fan assembly 100 through a standardpower transinission line so as to supply electrical power to the fan assembly 100 in a manner that will be described in greater detail herein below.
As further illustrated in Figure 1, each fan blade 3 16 may take the folm of a long narrow piece of aluminum with a hollow interior. In this particular embodiment, the fan blades 316 may be fabricated using a forced aluminum extrusion method of production in a manner as desci-ibed in greater detail herein below with reference to Figures 7A, 7B.
Advantageously, this allows liglitweight fan blades 316 witli considerable structural integrity to be produced in an inexpensivemanner. It also enables the fan blades 316 to be inexpensively fabi-icated with aerodynamic feattues, such as flanged trailing edges and airfoil contoured shapes. In addition, each fan blade 316 may be fabricated with a uniform cross-section along its length. However, it should be appreciated that altei7lative einbodiments may incoiporate extruded aluminum fan blades with a non-tuiiforin cross-section without departing fiom the scope of the present invention.
Moreover, the aerodynamic qualities of the fan blade 3 16 may be improved by forming a tapered trailing edge 514 on the fan blade 316, which may result in a more wiifol7n airflow fiom the fan assembly 100 as is discussed in greater detail with reference to Figures 5, 6. Also, using standard fasteners, a cap may be mounted on the distal ends of the fan blade 316 so as to cover the end openings and provide a continuous exterior surface. In one embodiment, the cap may comp.-ise a minimal structure that essentially matches the cross-sectional area of the fan blade 316.
Figure 2 illustrates one embodiment of the airflow patteni 200 generated by the fan assembly 100 of Figure 1. As illustrated in Figure 2, when a user places the fan assembly 100 into an operational mode by entering an appropriate input into the control box 102, a circulatoiy airflow 200 compiising, in one embodiment, gentle and/or Lulifoim airflow patterns may be generated throughout the building's interior 106. In one embodiment, the circulatory airflow 200 comprises a large slowly moving downward airflow 202 that is able to travel tllrough vast open spaces due to its large amount of inertial mass and because it travels away from the fan assembly 100 in a manner as described in the Applicant's issued U. S. Patent Number 6,244, 821.
In one aspect, the airflow 202 initially flows downward in a cohunnar manner towards a floor area 212 located beneath the fan assembly 100. As the airflow approaches the floor area 212, the airflow 202 is subsequently diverted by the floor area 212 to outwardly expand in a radial malmer as a lower ho~.-izontal airflow 204. Following, the lower horizontal air flow 204 is directed by the walls 214 of the warehouse into an upward airflow 206, which is further directed by the warehouse ceiling 110 into an upper inwardly moving horizontal airflow 210. Upon reaching a region 216 above the fan assembly 100, the returning air in airflow 210 is directed downward again by the action of the fan assembly 100, thus repeating the cycle. Advantageously, the circulating airflow 200 created by the fan asseinbly 100 provides a pleasant worlcing environment for individuals worlcing inside the warehouse interior 106.
Figure 3 illustrates a detailed side elevation view of the fan assembly 100 in Figlues 1, 2. The fan assembly 100 receives mechanical support fiom a support frame 302. The support fiame 302 includes an upper steel horizontal plate 322 that is adapted to attach to a suitable horizontal support structure adjacent to a ceiling such that contact is made between the support structure and a first surface 366 of plate 322 to thereby allow the fan assembly 100 to be mounted adjacent the ceiling. In one embodiment, the plate 322 is bolted to a ceiling support girder so that the fan assembly, 100 extends downward from the ceiling of the building in the maimer similar to that shown in Figure 1.
The fan assembly may furtller comprise an electric motor 304. The electric motor 304 may be adapted to receive an AC power source with a varying frequency which allows the electric motor 304 to produce a variable rotational speed. In one embodiment, the electric motor 304 may comprise an inverter duty electric motor manu.factured by Baldor Motor of America. Also, the electric motor 304 may comprise a built-in gear reduction drive or mechanism manufactured by Lenze of Germany that provides the necessaiy mechanical advantage to drive the large fan assembly 100. It should be appreciated that the maximum rate of power consumption of the electric motor 304 is approximately 370 watts.
The electric motor 304 may be mounted to the support fiame 302 in a mamier such that the axis of rotation of the motor 304 is along a vertical direction thus providing the fan assembly 100 with a driving torque. The motor shaft 306 transfers torque fiom the electric motor 304 to a hub 312 that is mounted on the shaft 306. The hub 312 inay comprise a single cast ahnnimnnpiece of material with a dislc-lilce shape that is adapted to secure a plurailty of fan blades 316. A plurality of blade supports 314 extend from a rim section 346 so as to extend radially outward fromthe axis of rotation defined by the motor 78348-23(S) shaft 306 by an approximate distance of 15 inches. The support blades 314have a paddle-lilce shape and are adapted to slip into the ends of aplurality of fan blades 316 to provide a means for mounting the fan blades 316 to the hub 312. A more tliorough discussion of the mechanical features of the fan assembly 100 including the mo-Lmting procedure of the fan blades 316 is describedin the Applicant's issued U.S. Patent Ivumber 6,244,821.
Figtue 4 is a view of the fan assembly 100 as seen from below and ilh.istiates the relationship between the hub 312, the set of blade supports 314 extending from the hub 312, and the set of fan blades 316 extending from the blade supports 314. Each faii blade 316 extends orthogonally from the rotational axis of the fan assembly 100 as defined by the motor shaft 306 in a manner that results in a tniiforrn distribution of the plurality of fan blades 316. In the one embodiment, the diameter of the fan assembly 100 may be fabricated with a diameter ranging from 8 feet up to 40 feet. This resi.ilts in the aspect ratio of each fan blade 316 to range between 8:1 up to 40:1. When the fan assernbly 100 is operating under normal conditions, the maximum blade tip velocity may range from approximate1y25 feetper second up to approximately 75 feetper second depending on the diameter of the fan assembly 100. In addition, the fan blades 3161nay be mounted to the hub 312 at an angle so as to improve perfoimance and efficiencyby increasing the volume of eoh.unnar air flow distributedby the fan assembly 100 during operation.
Figure 5 illustrates a cross-sectional view of the 'fan blade 316 at an arbitrary location along its length as seen by an observer looking towards the distal end of the fan blade 316 with reference to Figure 1, The fan blade 316 may comprise a first ctnved wall 524, a second curved wall 526, and a hollow interior region 522 formed therefrom. The two walls 524 and 526 may be joined together at leading junction. 531 and a trailing junction 532. At the trailingju.nction 532, the two walls 524,526 combine iul a continuous manner to form a third wall 530, wherein the third wall 530 continu.es until it reaches the reinforced trailing edge 514, whicli may be tapered so as to decrease in thiclaness across its length. Additionally, a first suiface 506 may be formed- at tlle exterior of wall 524 and continues in a seamless manner to the exterior of wall 530 until the reinforced trailing edge 5 14 may be reached. A second surface 510 may be foizned at the exterior of the wall 526 and continues in a seamless manner to the exterior of wall 530 until tlle reinforced trailing edge 514may be reached.
78348-23(S) In addition, the two surfaces 506, 510 meet at a leading edge 512. The hollow interior region 522, whicb may also be referred to as a cavity region, may comprise a rectangularly-shaped central section 500. A planar third surface 516 may be formed at the interior wal1524 in the region of section 500, and a planar fourth surface 520 may be formed at the interior of wall 530 in the region of section 500. In one aspect, the planar interior surfaces 516, 520 may be substantially parallel to each other. It should be appreciated that the fan blade 316 may comprise a solid interior region without departing from the scope of the present invention as is seen in FIG 5A. It should also be appreciated that the cross-sectional dimensions of the fan blade 316 including the reinforced trailing edge 514 will be described in greater detail herein below with reference to Figure 7B.
Moreover, the reinforced trailing edge 514 may comprise a downwardly extending flange 58 supported by a bent region 536. As illustrated in Figure 5, the reinforced trailing edge 514 extends from the trailing junction 532 in a manner so as to follow the curvature of the first curved wall 524. The distal end of reinforced trailing edge 514 bends downward in a manner so as to form the bent region 536 and the downwardly extending flange 538. The flange 538 distally extends from the reinforced trailing edge 514 via the bent region 536 and forms a first angle 540 with the reinforced trailing edge 514. Depending on the particular application and operation of the fan blade 316, the length of the flange 538 and the angular displacement of the first angle 540 may vary in magnitude without departing from the scope of the present invention.
The length of the flange 538 may comprise a magnitude between 0.125 (1/8) and 0.375 (3/8) inches, and the angular displacement of the first angle may comprise a magnitude between 80 and 100 degrees. In a preferred embodiment, the flange 538 .may comprise a length of approximately 0.25 (1/4) inches, and the first angle 540 may comprise an angular displacement of approximately 90 degrees. In addition, the fan blade 316 including the reinforced trailing edge may comprise extruded aluminum, but it should be appreciated that the fan blade 316 may comprise various generally known extruded materials without departing from the scope of the present invention.
In one aspect, the structural bend of the bent region 536 increases the strength of the distal end of the reinforced trailing edge 514 in a manner such that the structural bend improves rigidity by providing supporting forces in two dimensions relatively parallel and perpendicular to its length. The Applicant has observed that, during extrusion of the fan blade 316, the trailing edge without the bent region 536 or the flange 538 may waip, tear, or deform in a manner so as to adversely affect the stn.tctural integrity of the tra.iling edge.
For example, tearing of the unsuppoited trailing edge may occur during extrusion as a result of material being forced through an extrusion die such that pressure forces tend to tear unsupported regions. During formation, as the extruded material leaves the extrusion die, a pressure differential is created at the trailing junction 532 where the larger bulk material of the two exterior surfaces 506, 510 creates a large drifting pressure towards to the smaller bulk material of the trailing edge. Since the two exterior surfaces 506, 510 support each other at the trailing junction 532, the unsupported trailing edge is more susceptible to teariug as the length of the trailing edge 514 is made longer.
Unfortunately, a shorter trailing edge reduces the aerodynamic performance of the fan blade 3 16.
Conversely, the benefit of forming the fan blade 316 with a reinforced trailing edge 514 of the present invention results in improved stiltctural characteristics such that the reinforced trailing edge 514 may be fabricated longer so as to improve the aerodynamic performance of the fan blade 316. In one aspect, the reinforced trailing edge 514 resists damage and/or tearing that may occur during extrusion by adding the bent flanged region 536, 538 to the distal end of the trailing edge 514. For example, the bent portion 536 of the reinforced trailing edge 514 tends to rigidly orient the extru.ded material in a stabilized position more readily during foimation. Moreover, the bent portion 238 provides added strengtli by providing suppoiting forces in two dimensions that relatively parallel and peipendicular to its length so as to neutralize the adverse effects of presstue forces acting on the trailing edge of the fan blade 316. Additional benefits associated with the downwardly extending flange 514 will be described in greater detail below.
As illustrated in Figtue 5, the two exterior surfaces 506, 510 may be adapted to form the contour of an airfoil shape. For example, the airfoil shape may be based on the shape of a Geirnan sail plane wing having a reference number FX 62-K-131. In one aspect, the fan blade 316 may comprise a length between approxirnately 3 feet and 15 feet long and may be formed of an extruded metal so as to have a first air foil section 502 and a tapered trailing edge 514, wherein the flange 538 may be integrally foimed at the end of the tapered trailing edge 514 so as to reinforce the tapered trailing edge 514 and so as to provide increased douniward thrust dui.-ing rotation of the fan blades 316.
When the fan assembly 100 is in an operating mode, the cross-sectional image of the fan blade 316, as illustrated in Figures 1, 2, tilted by a coiTesponding angle of attack in a clockwise mamier would appear to travel with the leading edge 5 12 in fi-ont.
According to an observer fixed to an individual fan blade 316, the motion of the fan blade 316may cause air currents 600,602 along the surfaces 506, 5 10 of the fan blade 3 16, respectively. The airfoil shape of each faii blade 316 may fiuther cause the velocity of the upper air cutTent 534 to be greater than the velocity of the lower;air current 536. As a result, the air pressure at the lower surface 510may be greater than the air pressure at the upper surface 506. The apparent asyrnmetric airflows produced by the rotation of the fan blades 316 results an upward lift force F. to be experience by each fan blade 316. A
,, is therefore applied to the sw.ToLulding air by each fan reactive downward force FVe1,, blade 3 16. Moreover, the airfoil sliape of the fan blade 316 may reduce a horizontal drag force F acting on each fan blade 316, therefore resulting in a reduced horizontal force F1,U,j.,,,t being applied to the stiirrorun ding air by each fan blade 316.
Therefore, the airflow created by the fan assembly 100 may approximate a columnar flow of air along the axis of rotation of the fan assembly 100.
As further illustrated in Figure 6, the downwardly extending flange 538 enhances the performance of the fan blade 3 16. During rotation of the fan blade 3 16, the flange 538 may produce two counter rotating voitices 650, 652 adjacently downstream of the reinforced trailing edge 514. An upper vortex 650 may be produced by the upper stream of airflow 600 flowing above the fanblade 316, and a lower vortex 652 may be produced by the lower stream of airflow 602 flowing underneath the fan blade 316. In one aspect, the upper vortex 650 generates a pseudo pumping action that inaintains a lower pressure above the fan blade 316, thus effectively producing additional downward force F,.e~car Moreover, the counter rotating vortices 650, 652 virtually extend the length of the trailing edge 514 in a mamier such that the fan blade 316 produces additional downward force FVert;,,,. Even though the horizontal cha.g force F is slightly increased, the advantages of ,,,;., are sLtbstantial.
increasingthe downward forceFti,, Advantageously, the technical difficulties involved in designing the fan assembly 100 have been overcome by incoiporating innovative design features. In particular, the large fan blades 316 may be manufactured using an extiuded aluminum technique.
This metliod results in fan blades 316 that are stLUdy, lightweight, and relatively inexpensive to manufacture. The extrusion method may also enable the fan blades 3 16 to be fabricated with an airfoil shape, which enables a columnar airflow to be generated.
Figure 7A illustrates one embodiment of a plurality of extrusion manufactuiing components 700 including an extilision die 708 that may be used to foim an extri.ided fan blade 316 having a reinforced trailing edge 514. The material used for the extrusion process may comprise an extitiisionbillet 702, wherein the extrusionbillet 702 may be a solid or hollow piece of material that may be cylindrical in shape. In one aspect, the extrusion billet 702 may comprise alloyed aluminum in a generally known foim, such as a cast product, wrought product, or powder compact product that may be cut from a longer lengtli of material. It should be appreciated that alloyed materials may comprise one or more metallic elements without departing fiom the scope of the present invention. For example, aluminum based extrusion alloys may comprise small amounts of metallic elements such as copper, manganese, silicon, magnesium, or zinc.
Advantageously, these alloying elements enhance the nattual properties of aluminum and influence the extrusionprocess.
The extrusion billet 702 may vaiy in length depending on a number of pre-determined parameters including the desired lengtli of the finishedprofile, the extrusion ratio, the length of the rLui-out, and the requirements of the extrusion press. In one aspect, the length of the extrusion billet 702 may range from approximately 36 inches to about 40 inches. In addition, the outside diameter of the extrusion billet 702 may range from approximately 7 inches to about 8 inches. It should be appreciated that the outside diameter of the extrusion billet 702 may be as large as 14 inches without departing from the scope ofthepresent invention.
The next extrusion manufacturing component may comprise a heating fiirnace 704 that may be used to preheat the extrusion billet 702. During the extrusion process, the billet 702 is softened and/or softened in the heating furnace 704 so as to be more pliable.
The softening point of aluminiun varies with the purity of the metal, but is approximately 1,220' Fahrenheit (660 Centigrade). In one embodiment, the extiusion process may require the billet 702 to be heated to temperatures in excess of (375 C) and, depending upon the alloy being extruded, as high as 930 F (500 C).
The following manufacturing component may comprise an extrusion press 706 having an extrusion die 708. Figure 7B illustrates one embodiment of an extrusion die 708 that comprises a pattern similar in shape to the fan blade 3 16 having the reinforced trailing edge 514. The extrusion die 708 may coinprise a steel disk with an opening that may be sized and shaped to substantially match the intended cross-section of the final extruded profile of the fan blade 316. The opening or orifice runs completely through the extrusion die 708 so as to allow the softened billet 702 passage through from the front end to the back end. As is laiown in the art, dies may be grouped as solid (or flat) dies, which produce solid shapes, and hollow dies, which produce hollow or semi-hollow shapes, such as the fan blade 3 16 as illustrated in Figures 5, 6.
Combinations of solid, semi-hollow, and/or hollow shapes may be incoiporated into a single die, wherein a solid die may have one or more orifices or apertures tlirough which the softened alloy is forced (extruded). As illustrated in Figure 7B, the extrusion die 708 die may be used to produce hollow profiles by means of a fixed or floating mandre1720. Advantageously, the use of the extrusion die 708 with the mandrel 720 for extruding the fan blade 3 16 produces a hollow shape. Witllout departing from the scope of the present invention, it should be appreciated by one skilled in the art that the extrusion die 708 may be formed without the mandre1720 so as to produce an extruded fan blade 3 16 with a solid interior region.
As is known in the art, the extrusion press may further comprise an extrusion press container that houses the billet 702 and a ram that may be used to apply pressure and/or force to the billet 702 within the container. Various hydraulic extrusion presses may be capable of exerting anywhere from 100 tons to 15,000 tons of pressure, wherein the pressure capacity of the extrusion press determines how large an extrusion it may produce. When pressure is applied, the billet 702 is forced against the die 708 and expands until restricted by contact with the walls of the container. Then, as the pressure increases, the soft (but still solid) metal forced to squeeze out through the shaped orifice of the extrusion die 708 in a maimer so as to emerge on the other side of the extrusion die 708 as a formed profile of the fan blade 316. Subsequently, the extruded fan blade 3 16 may be removed from the back end of the extrusion die 708. After the extruded fan blade 316 is removed fiom the extrusion die 708, the still-hot extruded fan blade 316 maybe quenched, mechanically treated, and aged.
In one embodiment, the cross-sectional dimensions and/or profile of the extruded fan blade 3 16 may comprise a width between approximately 5 inches and 8 inches and a height between approximately 0.75 (3/4) hiclies and 1.50 (3/2) inches. In a preferred embodiment, the cross-sectionaldiinensions of the fanblade 316may comprise a width of approximately 7 inches and a height of approximately 1 inch. Also, the thickness of the first, second, and third curved walls 524, 526, 530 may be between approximately 0.0625 (1/16) inches and 0.1875 (3I16) inches thick. In apreferred embodiment, the thickness of the walls 524, 526, 530 inay be approxhnately 0.15625 (5/32) inches thick.
Alteiliatively, the third wall 530 may comprise a tapered shape so as to decrease in thiclrness from approxiinately 0.1875 (3/16) inches at the trailing junction 532 across its length to approximately 0. 0625 (1/16) inches at the reinforced trailing edge 514.
Additionally, depending on the size of the billet 702 and the size of the die opening, a continuous extrusion as much as 100 feet long may be produced witli each stroke of the extrusion press 706. The newly-forined extruded fan blade 316 may be supported on a ilin-out conveyor as the extruded fan blade 316 leaves the extrusion press 706. The extrusion may then be transferred to a cooling table and cooled after emerging from the die 708 through the use of air or water quenches.
The next manufacturing component may comprise a straightener 710 and a saw 712, wherein the straightener 710 may be used, after the extruded profile has been cooled to straighten the profile and correct any twisting that may have occurred subsequent to the extiusionprocess. After straightening, conveyors may be used to feed the extruded fan blade 316 to the saw 712. The saw 712 may coinprise a finish cut saw that may be used to cut the extruded profile to a desirable length. In one embodiment, the finish cut dimensions of the extn.ided fan blade 3 16 may comprise a length between approximately 4 feet and 15 feet. In a preferred einbodiment, the fmish cut dimensions of the fan blade 3 16 may comprise a length of approximately 112 inches. Also, circular saws and/or a radial arm saw may be used to cut across the profile at an angle that is substantially peipendicular to the length of the extruded profile. In various otller embodiments, the saw 712 may comprise a power initer saw, that drops down onto the profile, or a table saw with a circular blade that rises to cut the extruded profile. A
typical finish cut saw may be 16 to 20 inches in diameter with carbide-tippedteetll.
The following manufacturing component may comprise an aging oven 714. As is lcnown in the art, some extrusion alloys reach their optimal strength through the process of aging, which may be refeiTed to as age-hardening. Natural aging may occur at room temperature, and artificial aging may comprise controlled heating in the aging oven 714, which may be referred to as precipitation heat-treating. In one aspect, when the extruded profile emerges from the extrusion press 706, the extruded profile may comprise a semi-solid state, but rapidly solidifies as it cools or is quenched. It should be appreciated that aluminum alloys, such as those comprising manganese or magnesium, derive their strength through natural aging and cold worlcing. Alternatively, other aluminum alloys, such as those comprising copper, zinc, and magnesium with silicon, may be fiuther strengthened or hardened through controlled tllermal treatments that affect the metallurgical structure of the alloys. Consequently, the aging process may ensure substantially uniform precipitation of fine particles through the metal, yielding increased strength, hardness, and elasticity for the specific extrusion alloy.
The extrusion process, as describedwith reference to Figure 7A, may be utilized to shape the fan blade 316 having a continuous cross-section by forcing the extrusion billet 702 through the extrusion die 708, which comprises a profile opening of the fan blade's 316 cross-section as illustrated in Figure 7B. The process of forming the extruded fan blade 316 having the reinforced trailing edge 514 may proceed as follows.
The extrusion die 708 may be prepared and attached to the extrusion press 706.
Next, the extrusion billet 702, which preferably comprises an aluminum alloy, may be placed in an extrusion press container and preheated in the heating furnace 704. The pliable billet 702 may be forced tlirough the exti-usion die 708 by applyiing pressure to the billet 702 using the extrusion press 706 in a Ynaimer so as to form the fan blade 3 16 with the reinforced trailing edge 514. Once the extruded profile of the fan blade 316 is cooled and straightened in the straightener, the extruded profile may be cut using the saw 712 at pre-determined intervals so as to form a plurality of fan blades 316 with the desired length of the fan blade 316 from the extruded profile. Additional processing may comprise aging the extruded fan blades 316 in a manner as previously described. After processing the extru.ded fan blades 3 16, the process of forming the fan blades 3 16 is coinpleted.
Advantageously, the technical difficulties involved when extruding the fan blade 316 have been overcome by reinforcing the trailing edge 514 with the bent region 536 and the downwardly extending flange 538. Since the large fan blades 316 are formed using an extruded ahuninum technique, the formation process results in improved fan blades 316 that comprise enhanced structural characteristics, such as improved rigidity, sturdiness, and resiliency. The extrusion method may also enable the fan blades 3 16 to be fabricated with enhanced aerodynamicperfoimance characteristics, which enables a larger columnar airflow to be generated during operation. Therefore, the improved design of the above-mentioned fan assembly 100 with iinproved fan blades 316 having the reinforced trailing edge 5 14, as described herein, comprises a significant improvement over the prior art.
Although the preferred einbodiment of the present invention has shown, described, and pointed out the fundamental novel features of the invention as applied to this particular embodiment, it will be tmderstood that various omissions, substitutions and changes in the form of the detail of the device illustrated may be made by those skilled in the art without departing froin the spirit of the present invention.
Consequently, the scope of the invention should not be limited to the foregoing description, but should be defined by the appending claims.

Claims (34)

CLAIMS:
1. A fan assembly for circulating air in an industrial building, the fan assembly comprising:

a support adapted to allow the mounting of the fan assembly to the roof of the industrial building;

a motor coupled to the support, the motor engaged with a rotatable shaft so as to induce rotation of the shaft; and a plurality of airfoil shaped fan blades attached to the rotatable shaft, wherein each fan blade is formed of an extruded material such that a first curved wall is joined to a second curved wall to form a leading junction and a trailing junction, and wherein the trailing junction extends to form a third curved wall having a tapered trailing edge, each blade further comprising a bent flange that distally extends from the trailing edge in a continuous manner that reinforces the trailing edge.
2. The fan assembly of Claim 1, wherein the flange downwardly extends from the lower surface of the third wall.
3. The fan assembly of Claim 1, wherein the first curved wall is joined to the second curved wall to form a hollow interior region.
4. The fan assembly of Claim 1, wherein the first curved wall is joined to the second curved wall to form a solid interior region.
5. The fan assembly of Claim 1, wherein each fan blade comprises a cross-sectional width between approximately 5 inches and 8 inches.
6. The fan assembly of Claim 1, wherein each fan blade comprises a cross-sectional height between approximately 0.75 (3/4) inches and 1.50 (3/2) inches.
7. The fan assembly of Claim 1, wherein each fan blade comprises a length between approximately 4 feet and 15 feet.
8. The fan assembly of Claim 1, wherein the first and second curved walls comprise a thickness between approximately 0.0625 (1/16) inches and 0.1875 (3/16) inches.
9. The fan assembly of Claim 1, wherein the third curved wall comprises a tapered shape that decreases in thickness across its length from approximately 0.1875 (3/16) inches at the trailing junction to approximately 0.0625 (1/16) inches at the trailing edge.
10. The fan assembly of Claim 1, wherein the flange comprises a length between approximately 0.125 (1/8) and 0.375 (3/8) inches.
11. The fan assembly of Claim 1, wherein the plurality of fan blades are attached to a hub, which is connected to a rotatable shaft.
12. The fan assembly of Claim 1, wherein the plurality of fan blades includes at least ten fan blades.
13. The fan assembly of Claim 1, wherein each of the plurality of fan blades are fabricated using an extrusion technique.
14. The fan assembly of Claim 1, wherein the extruded material comprises aluminum.
15. A metal fan blade for a fan assembly used in an industrial building, the fan blade comprising an extruded cross-sectional profile with a cross-sectional width of approximately 7 inches and having a plurality of curved walls, wherein a first curved wall is joined to a second curved wall to form an airfoil shape and the first curved wall is extended to form a tapered trailing edge wherein the distal end of the tapered trailing edge is bent to form a flanged portion extending outward from the direction of the trailing edge, wherein the flanged portion of the trailing edge downwardly extends from the lower surface of the trailing edge such that the angular displacement of the flanged portion from the lower surface of the trailing edge forms a reinforced region that increases the structural rigidity of the trailing edge so that the flanged portion of the trailing edge resists damage, and wherein the flanged portion increases the volume of airflow.resulting from the operation of the fan assembly having the fan blade.
16. The fan blade of Claim 15, wherein the first curved wall is joined to the second curved wall to form a hollow interior region.
17. The fan blade of Claim 15, wherein the first curved wall is joined to the second curved wall to form a solid interior region.
18. The fan blade of Claim 15, wherein the extruded cross-sectional profiles comprises a cross-sectional height of approximately 1 inch.
19. The fan blade of Claim 15, wherein the fan blade comprises a length of at least 4 feet.
20. The fan blade of Claim 15, wherein the fan blade comprises a length of at least less than 15 feet.
21. The fan blade of Claim 15, wherein the first and second curved walls comprise a thickness of approximately 0.15625 (5/32) inches.
22. The fan blade of Claim 15, wherein the trailing edge comprises a tapered shape that decreases in thickness across its length.
23. The fan blade of Claim 15, wherein the flanged portion comprises a length between approximately 0.125 (1/8) and 0.375 (3/8) inches.
24. The fan blade of Claim 15, wherein the fan blade is fabricated using an extrusion die to form the extruded cross-sectional profile of the fan blade.
25. The fan blade of Claim 15, wherein the fan blade is formed using an aluminum extrusion technique.
26. A fan assembly for cooling industrial buildings, the fan assembly comprising:

a mounting assembly having a rotatable hub that attaches the fan assembly to the ceiling of the industrial building; and a plurality of fan blades mounted to the rotatable hub, wherein each of the plurality of fan blades is at least 4 feet long and is formed of an extruded metal so as to have a first air foil section formed of a first curved wall, a leading edge and a tapered trailing edge, the tapered trailing edge extending outward from the rotatable hub, wherein the tapered trailing edge extends from the first curved wall of the fan blade and wherein the tapered trailing edge is bent at a distal end to integrally form a flange to reinforce the tapered trailing edge and so as to provide increased downward thrust during rotation of the fan blades.
27. The fan assembly of Claim 26, wherein the first curved wall is joined to a second curved wall to form the first air foil section having a hollow interior region.
28. The fan assembly of Claim 26, wherein the plurality of fan blades are formed using an extrusion fabrication process.
29. The fan assembly of Claim 26, wherein the flange reinforces the tapered trailing edge during the extrusion fabrication process so that the tapered trailing edge resists tearing while being formed.
30. The fan assembly of Claim 26, wherein each of the plurality of fan blades comprises aluminum.
31. A fan assembly for circulating air in an industrial building, the fan assembly comprising:

a support adapted to allow the mounting of the fan assembly to the roof of the industrial building;

a motor coupled to the support, the motor engaged with a rotatable shaft so as to induce rotation of the shaft; and a plurality of fan blades attached to the rotatable shaft, wherein each fan blade is formed of an extruded metal such that a first curved wall is joined to a second curved wall to form a leading junction and a trailing junction, and wherein the trailing junction extends to form a third curved wall having a tapered shape that decreases in thickness across its length from approximately 0.1875 (3/16) inches at the trailing junction to approximately 0.0625 (1/16) inches at a trailing edge, each blade further comprising a flange that distally extends from the trailing edge in a continuous manner such that the angular displacement of the flange from the trailing edge forms a bent region that reinforces the trailing edge.
32. A metal fan blade for a fan assembly used in an industrial building, the fan blade comprising an extruded cross-sectional profile having a plurality of curved walls, wherein a first curved wall comprising a thickness of approximately 0.15625 (5/32) inches is joined to a second curved wall comprising a thickness of approximately 0.15625 (5/32) inches to form an airfoil shape having a trailing edge that includes a flange extending outward from the direction of the trailing edge, wherein the flanged portion of the trailing edge downwardly extends from the lower surface of the trailing edge such that the angular displacement of the flanged portion from the lower surface of the trailing edge forms a reinforced region that increases the structural rigidity of the trailing edge so that the flanged trailing edge resists damage, and wherein the flange increases the volume of airflow resulting from the operation of the fan assembly having the fan blade.
33. The fan blade of Claim 32, wherein the trailing edge comprises a tapered shape that decreases in thickness across its length.
34. The fan blade of Claim 32, wherein the flange comprises a length between approximately 0.125 (1/8) and 0.375 (3/8) inches.
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US10/338,820 US6939108B2 (en) 2003-01-06 2003-01-06 Cooling fan with reinforced blade
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