Patent Abstract:
An HVLS fan system uses STOL technology for airfoils and angle of attack thus optimizing air movement efficiency and reducing drag. The HVLS fan system includes wingtip fence end caps to the airfoils for improving efficiency by reducing drag. The HVLS fan system also includes an interconnection of the airfoils to a securing plate thus providing a failsafe and reduced potential for damage or injury resulting from failure of the connection between the airfoil array and a drive unit such as an electric motor and associated gearing.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to two provisional patent Applications Nos. 61/661,619 and 61/661,622 filed on Jun. 19, 2012. The disclosure of the prior applications are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The invention generally relates to high volume low speed (HVLS) fans, and more specifically HVLS fans utilizing short take off and landing (STOL) technology. 
     BACKGROUND OF THE INVENTION 
     Interior climate control and air circulation is difficult in certain applications, particularly including large open structural areas such as found in a factory or warehouse setting. This difficulty is encountered in both hot and cold seasonal conditions, where heat during cold weather heating migrates towards the ceiling of a building and humidity tends to migrate down during hot and humid weather conditions. Therefore, there is an interest in forcing air from the ceiling, down, towards an occupied main floor during cooler weather, thus saving costs for heating, and circulating air more generally in warmer weather conditions resulting in a perceived cooler environment due to evaporation. Solutions to these conditions include forced ventilation through ceiling-based plenums in HVAC applications. Another solution is the use of ceiling fans to circulate the ambient air. However, both of these solutions are inadequate for circulating large volumes of air in large open areas such as is common in a factory or warehouse setting. 
     HVLS fans provide improvement over HVAC systems and/or traditional ceiling fans by moving larger volumes of air. These systems have their own limitations including relatively low efficiency in both the amount of energy used and amount of circulated air per unit of energy use. 
     STOL technology is a known solution for allowing aircraft to take off and land within constrained short distances. STOL technology has been adapted to aircraft airfoil profiles for providing improved lift and efficient movement of air under slower take off or landing speeds. Known aircraft wing profiles utilizing STOL design technology include EPPLER-420 and FX63-137 profiles. But, these airfoil profiles utilizing STOL design technology have not been adapted for use in HVLS fan systems. 
     In addition, due to their size and weight resulting from fans reaching diameters from 12 feet to 20 feet, or more, there is risk to persons and equipment below the fan in the event of a failure causing a portion, or all, of the fan to fall. 
     Therefore, there is opportunity and need for improving air circulation systems in large open areas. Further, there is need for improving HVLS fan systems to provide higher efficiencies and maximize airflow in large open spaces such as warehouses, manufacturing facilities, places of worship, gymnasiums/health clubs, auto dealerships and more. There is also a need for providing safety measures in the implementation of HVLS fan systems. 
     SUMMARY OF THE INVENTION AND ADVANTAGES 
     The present disclosure addresses these needs and issues by providing an HVLS fan system incorporating STOL technology in a system that increases air volume and circulation while also increasing efficiencies and which does not add significant costs, weight, or manufacturing complexity to this system. 
     It is therefore an object of the disclosure to take advantage of STOL technology and thus increase efficiency of an HVLS fan system. It is a further object of the disclosure to provide greater efficiency in the movement of air in the HVLS system. It is an additional object of the disclosure to provide an economical and lightweight solution to better circulate air in large areas. Another object of the disclosure is to provide a safety mechanism for preventing injury or damage in the event of a failure in the HVLS fan. 
     The present disclosure provides an HVLS fan system utilizing STOL technology and having better efficiency, including an airfoil form adapted to provide higher airflow at lower circulation rates while decreasing drag on the airfoils and increasing efficiencies. The system also includes an airfoil profile consistent with STOL technology. More particularly, an airfoil utilizing an EPPLER 420 or substantially similar airfoil design. In addition, the system includes a wing tip advantageously formed to reduce drag of the airfoil. Further, the system employs a hub displacing the airfoil at an angle most suitable for maximizing the benefits of the STOL technology. More particularly, this includes a hub providing an attachment angle of between seven and ten degrees to the airfoil, and even more particularly eight degrees to the airfoil. Together, the disclosure provides an HVLS fan system offering improved efficiency, reduced drag, and increased air flow for the benefit of better circulating air in a large open area. 
     In addition, the system includes a safety system including attachment of a retaining member, one for each airfoil, on the hub that passes through a retaining bracket in a manner that in the event of the airfoil becoming dislodged from the hub or the hub itself becoming disconnected from the drive system prevents the hub and/or the airfoils from falling. The retaining brackets do not touch or otherwise notably increase air resistance in the system but provide for an important safety measure where failure can cause catastrophic consequences. Another safety aspect is a series of overlapping brackets which mount on the top of the airfoils which interlock each of the airfoils to the one next to it. This will prevent an airfoil from becoming dislodged from the system in the case of failure. In addition, guy wires connect the frame of the HVLS fan system to a support member such as a ceiling support beam. 
     Other objects and features of the present invention will become apparent when viewed in the light of the detailed description of the preferred embodiments when taken in conjunction with the attached drawings and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of the HVLS fan system of the invention; 
         FIG. 2  is a side sectional view in spaced apart form showing the HVLS fan system of  FIG. 1 ; 
         FIG. 3  is a side cross sectional view of an airfoil of the HVLS fan system; 
         FIG. 4  is a top view of an airfoil of the HVLS fan system; 
         FIG. 5  is a side view of a wingtip fence of the HVLS fan system; 
         FIG. 6  is a top view of the wingtip fence of  FIG. 5 ; 
         FIG. 7  is a back view of the wingtip fence of  FIG. 5 ; 
         FIG. 8  is a top view of a central hub of the HVLS fan system; 
         FIG. 9  is a side view of the central hub of  FIG. 8 ; 
         FIG. 10  is a perspective view of a cylinder of the HVLS fan system; 
         FIG. 11  is a cross-sectional view of the cylinder of  FIG. 11 ; 
         FIG. 12  is a top view of a securing plate of the HVLS fan system; 
         FIG. 13  is a perspective view a of portion of the HVLS fan system in spaced apart form emphasizing the locations of safety brackets; and 
         FIG. 14  is a table containing X-Y data coordinates for the airfoil profile of the HVLS fan system. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following figures, like reference numerals are used to identify identical components in the various views and embodiments. The following example is meant to be illustrative of preferred embodiments for the invention. However, those skilled in the art will recognize various additional alternative embodiments. 
     Referring to  FIGS. 1-13 , an HVLS fan system  10  of the disclosure includes airfoils  12  coupled at one end to a central hub  14  and extending in the other direction to a distal end having a wingtip fence  16 . The central hub  14  is coupled to a motor  18  for rotating the airfoils  12 . The motor  18  is connected to a frame  20  which is coupled to a lower yoke  22  and an extension bar  24  which in turn is coupled to an upper yoke  26 . The upper yoke  26  is illustrated as connected to a building member  28  such as a girder or other similar structures suitable for bearing the weight of the HVLS fan system. The extension bar  24  as a backup secures the HVLS fan system to the building member  28  with a safety cable  30 . Guy wires (not shown) are also used to secure the frame to weight bearing locations on either the builder member  28  or other support structure in the ceiling of the building. Typically, four guy wires are used and attached at somewhat equally spaced locations around the HVLS fan system. 
     As illustrated, the HVLS fan system has six airfoils  12  equally spaced around the central hub  14 . The HVLS fan system airfoils  12  are generally positioned between ten feet and fifty feet above the floor with optimum height generally between twenty feet and thirty feet. The motor  18  is a standard approximately one horsepower electric motor known to those skilled in the art. To accomplish the objective of HVLS, the airfoils  12  are each between five and twelve feet in length and more preferably between six and ten feet in length. Looking up at an installed HVLS fan system  10  it will rotate in a counterclockwise direction  32 . 
     The airfoils  12  are formed out of a lightweight material such as aluminum or a composite metal that can be formed into an airplane wing type shape with a hollow core. However, it should be appreciated that the airfoils can be formed of a variety of different materials, including plastics, polyurethanes, and other suitably rigid materials adequate to form an airfoil, or even combinations of such materials known to those skilled in the art. It should also be appreciated that the length of the airfoils  12  can be increased or decreased to suit a certain application. In addition, it should be appreciated that the HVLS fan system  10  can include airfoils  12  without inclusion of wingtips fences  16 . Further, motor  18  may be any manner of other suitable motor including suitable horse power or amperage rating know to those skilled in the art. 
     The airfoils  12  are fan blades comprised of a generally elliptical top surface  34  and a generally elliptical bottom surface  36 . The airfoils  12  are configured to mount to the central hub  14  through the use of an H-shaped connector member  37 , connected on one end to the central hub  14  and on the other end to a receptors  39  interior to the airfoil  12 . The airfoil further includes a leading edge  38  and a trailing edge  40 . The trailing edge  40  maintains a radius of approximately 0.043 inches. 
     The airfoil may be a substantially hollow extruded aluminum section of approximately 0.1 inches in thickness when mounted to the central hub  14  including STOL-type airfoils. The wingtip fence  16  has a substantially vertical member  42  with a connecting perimeter  44  defined by the profile of the airfoil  12 , to which it is attached. The wingtip  16  consisting of a lower concave edge  46 , an upper convex edge  48 , a leading  50  and trailing edge  52  which sits flush with the airfoil  12  end edge. The vertical member  42  protrudes rearward relative to the leading edge  50  of the airfoil  12 . The vertical member  42  consists of two planes. The lower plane is parallel to the connection plane of the airfoil and wingtip fence, while the upper plane is angled outward relative to the innermost end of the airfoil. Adding the wingtip fence  16  to the airfoils  12  improves the aerodynamic properties of the airfoils, by reducing drag and therefore increasing the fan&#39;s overall efficiency. 
     The wingtip fence  16  includes a mounting member  54  which connects to an inner portion of the receptors  39  of the airfoil  12 . The wingtip  16  is configured to secure the connection to the airfoil  12  through protruding guide points  56  that couple to an inner perimeter of the airfoil  12  thus mounting the wingtip fence  16  to the airfoil  12 . 
     The central hub  14  provides a securing system for the fan assembly, where a bottom frame member  58  is connected to a securing plate  60  by fasteners  62 . The central hub  14  assembly includes a cylinder  64  coupled to the central hub  14  and retaining members  68 , one for each of the airfoils  12  that when connected to the central hub  14  extend through an opening in the securing plate  60  thus providing a safety stop against a failure involving a break in the motor  18  or its coupling to the cylinder  64  or a drive shaft  70 . The cylinder  64  has an opening  72  for receiving the drive shaft  70 . The drive shaft  70  does not connect directly to the cylinder  64 , but instead couples to a bushing (not shown) which couples the drive shaft  70  to the cylinder  64  through simultaneous expansion and contraction, as is known to those skilled in the art. 
     The central hub  14  includes flanges  74  which are displaced from a plane defining the central hub at an angle predetermined for the airfoils  12 . The angle of the flanges  74  positions the airfoils  12  at an angle most suitable for maximizing the benefits of the STOL technology. More particularly, this includes an attachment angle of between seven and ten degrees to the airfoil, and even more particularly eight degrees to the airfoil. 
     Another safety aspect is a series of overlapping brackets including a first bracket  76  and second bracket  78  which mount on the top of the airfoils and interlock each of the airfoils  12  to the one next to it. The first bracket  76  and second bracket  78  are held in place with fasteners  80 . This prevents the airfoil  12  from becoming dislodged from the system in the event of failure. In addition, guy wires (not shown) connect the frame of the HVLS fan system to a support member such as a ceiling support beam. 
     After applicants first conceived that STOL technology would benefit efficiencies and overall performance of an HVLS fan, experimentation was undertaken under preset parameters and requirements to optimize a STOL airfoil profile. This experimentation, undertaken at the request and direction of the applicants by Haiyer Lou, Ph.D, M. Eng at TurboMoni, confirmed that of two airfoil profiles adapting STOL technology an airfoil following EPPLER-420 parameters was more efficient when angled at approximately 8 degrees from horizontal. Thus, referring to  FIG. 14 , the airfoils  12  are predetermined to comply with STOL technology and provide high efficiency operation including higher lift and lower drag for the application of an HVLS fan. The EPPLER-420 profile disclosed in  FIG. 14  provides dimensionless cord lengths that provide for defining X-Y coordinates by multiplying with the real cord (the distance from leading edge point to the trailing edge point). 
     Thus, an HVLS fan system of the invention, including its various embodiments, provides a high efficiency cost effective, secure means of addressing and providing air movement in large open areas. 
     While particular embodiments of the invention have been shown and described, numerous variations and alternative embodiments will occur to those skilled in the art. Accordingly, it is intended that the invention be limited only in terms of the appended claims.

Technology Classification (CPC): 5