Abstract:
An overhead door system featuring independent, unconnected panels is described. Each panel end is operatively carried within a pair of parallel tracks. The weight of the door decreases as the door is lifted and each panel completely disengages from its adjacent panel as it reaches the stacked position. This allows for a linear spring torque to door weight relationship requiring a very small motor compared to existing designs to provide the lifting torque necessary to operate the door.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates generally to overhead doors, and in particular, to an overhead door with stacking panels. 
       BACKGROUND OF THE INVENTION 
       [0002]    Overhead doors are utilized to provide security and access control in institutional, industrial and commercial buildings. They fall into two general design categories: coiling doors and segmented panel doors. Each have their advantages and disadvantages making one better suited for a given design application. 
         [0003]    Often times a segmented panel door is better suited for a particular application but cannot be used due to the increased space requirement needed to house the panels once the door is opened. Various attempts have been made to reduce the profile of the opened door, such as stacking the panels as taught in U.S. Pat. No. 4,460,030 to Tsunemura et al. and in U.S. Pat. No. 5,685,355 to Cook et al. 
         [0004]    The stacking design of those two patents, as do all other known panel stacking designs, maintain a connection point between the panels such as a hinge, or otherwise link the opened panels, for example, with chains, to support the weight of the panels during opening. 
         [0005]    Having to maintain a connection point between the panels presents many disadvantages such as placing limitations on the ease of repair of damaged panels and requiring higher energy consuming operators to open the door. Accordingly, there is still a continuing need for improved stacking panel overhead door designs. The present invention fulfills this need and further provides related advantages. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    The following disclosure describes a stacking panel overhead door design wherein the panels are independent of one another. 
         [0007]    One advantage of unconnected stacking panels is the spring torque to door weight ratio is easy to control. The weight of the door decreases as the door is lifted and a panel disengages completely from its adjacent panel as it reaches the stacked position. This allows for a linear spring torque to door weight relationship requiring a smaller motor compared to existing designs to provide the lifting torque necessary to operate the door, thereby providing concomitant energy savings. Chart A represents the spring torque to door weight ratio. 
         [0008]    A second advantage of independent stacking panels is the ease of replacement or repair of a damaged panel. 
         [0009]    Other features and advantages of the present design will be apparent from the following more detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The accompanying drawings are included to provide a further understanding of the present invention. These drawings are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the present invention, and together with the description, serve to explain the principles of the present invention. 
           [0011]    Chart A represents an ideal spring torque curve. 
           [0012]      FIG. 1  is a front view of the overhead door system. 
           [0013]      FIG. 2  is a perspective view of a panel. 
           [0014]      FIG. 3  is an end view of a panel without the end cap. 
           [0015]      FIG. 4  is a side view of two engaged panels without the end cap. 
           [0016]      FIG. 5  is a front view of an end cap with the roller assemblies. 
           [0017]      FIG. 6  is a side view of stacked door panels in the open position. 
           [0018]      FIG. 7  is a perspective view of the drive mechanism. 
       
    
    
       [0019]    Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings which illustrate by way of example the principles of the invention. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    As required, detailed embodiments of the present invention are disclosed; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various forms. The figures are not necessary to scale and some features may be exaggerated to show details of particular components. Therefore, specific structural and functional details disclosed are not to be interpreted as limiting but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention. Where possible, like reference numerals have been used to refer to like parts in the several alternative embodiments of the present invention described herein. 
         [0021]    Turning now to  FIG. 1 , in a preferred embodiment, the overhead door  2  comprises a plurality of unconnected panels  4  which operatively travel at each end within a first  6  and second  8  track ( FIG. 6 ). 
         [0022]    As shown in  FIGS. 2 and 3 , each panel  4  comprises an outer  10  and inner  12  surface with preferably an insulating material  14  in-between. A top  16  and bottom  18  edge each comprise a geometry that allows for engagement and disengagement of its adjacent panel during operation. 
         [0023]    Turning to  FIG. 5 , end caps  46  are fastened at each panel end. While end caps  46  in and of themselves are not required for operability, the end caps  46  provide esthetic advantages, operative engagement advantages, and fewer panel component parts. When the panels  4  are stacked, the end caps  46  contact each other, not the panels  4 , thereby limiting the bumping and disfigurement of the panels  4 . Instead of the time consuming task of separately mounting a first  26  and second  28  positioning assembly, activation engagement member  34 , and panel guide  38  (described in detail below) to each panel  30 , a prefabricated end cap  46  containing those components is fastened to each panel end  30 . The end caps  46  are preferably molded of high impact plastic. 
         [0024]    All panels  4 , including the bottom panel  48  are interchangeable to allow for easy removal of a damaged panel and replacement. The bottom panel  48  ( FIG.1 ) includes a removably attached weather seal and/or sensing edge  50  affixed to its bottom edge  18  that is removed and reattached to the replacement bottom panel. The end caps  46  of the bottom panel  48  are operatively engaged to a drive mechanism  64  ( FIG. 7 ), for example a cable, chain, belt, or piston. 
         [0025]    When the drive mechanism  64  is a cable, the cable arrangement provides the cable  64  an effective operative cable geometry that will allow the cable  64  to operatively wrap on a cable drum  66 . As shown in  FIG. 7 , to achieve this, in a preferred embodiment, the cable  64  is positioned vertically from the panel cable attachment  68 , around a first pulley  70  mounted to a vertical pulley bracket  78 , and then around a second pulley  72  mounted to a horizontal pulley bracket  80  and positioned about 15 inches to about 17 inches, optimally about 16 inches behind a wall attachment  82  before the cable  64  wrap on the cable drum  66 . 
         [0026]    Turning to  FIGS. 3 and 4 , for the top edge geometry a lip  20  is angled in relation to outer panel surface  10  forming angle α. Likewise, trough  22  is angled in relation to inner panel surface  12  forming angle β. For the bottom edge geometry the lip  20  is angled in relation to inner panel surface  12  forming angle α. Trough  22  is angled in relation to outer panel surface  10  forming angle β. When two panels  4  are fully engaged ( FIG. 4 ) the lip  20  of the first panel nests intimately within the trough  22  of its adjacent panel. The lip  20 /trough  22  geometry allows adjacent panels to nest and prevents engaged panels from separating, thereby insuring security, improving the wind load rating, and providing added weather protection. Preferably, a thermal break piece  24 , shown in  FIG. 3 , is attached to each panel  4 . Multiple points of contact between the panel top edge thermal break piece  54  and panel bottom edge thermal break piece  56  increase the surface area of the joint to provide a more complete air infiltration seal. In the preferred embodiment, top and bottom thermal break pieces  54 ,  56  are fabricated from PVC. 
         [0027]    To insure proper panel engagement/disengagement during door closing and opening and to prevent water from traveling from the outside environment to the inside environment, angles α and β are about 10 degrees to about 25 degrees, preferably about 15 degrees to about 20 degrees and optimally about 18 degrees. 
         [0028]    While the following elements may be attached directly to a panel  4 , for the advantages described above, in a preferred embodiment they are fabricated as part of the end cap  46 . As shown in  FIG. 5 , a first  26  and second  28  positioning assembly, for example, bearing assemblies, are attached to each end  30  of panel  4 . The first positioning assembly  26  comprises a first engagement member, for example, a bearing  32 , extending outward from panel outer surface  10  to operatively engage the first track  6 . An activation engagement member, for example, an activation bearing  34 , is positioned to operatively engage the panel guide  38  of the adjacently superior panel during opening and closing of the door  2 . 
         [0029]    Activation engagement member  34  aids in engaging/disengaging the lip  20  and trough  22  of adjacent panels by riding on the panel guide  38  around the panel bottom edge radius  40  to nest the panels in the fully engaged (door closed) position. Bearing  34  remains in contact with panel guide  38  in the stacked position, the fully closed position, and throughout the panel engagement/disengagement operation. 
         [0030]    The second positioning assembly  28  comprises an engagement member, for example, a bearing  36 , extending inward from the panel inner surface  12  to operatively engage the second track  8 . 
         [0031]    Although optional panel stiffeners may be added to the panel  4 , the present design does not require any stiffeners to be operatively effective, providing additional benefit over known sectional door designs which require stiffeners to achieve equivalent wind load ratings. In a preferred embodiment the insulating material  14  comprises an expandable foam injected between the outer  10  and inner  12  panel surface. While bearings have been used as exemplars for the engagement members, any low friction member, for example, PTFE pads are also contemplated. 
         [0032]    Turning now to  FIG. 6 , each set of first  6  and second  8  tracks are fixed to both sides of a door opening frame member  76  in known fashion. In a horizontal section  42  of tracks  6 ,  8 , the tracks  6 ,  8  are separated by a distance equal to the width of a panel  4 . In a vertical section  44  of tracks  6 ,  8 , the tracks  6 ,  8  are separated by a distance equal to the thickness between the first engagement member (bearing)  32  and the second engagement member (bearing)  36 . The transition between the horizontal section  42  and the vertical section  44  is accomplished through radii γ and δ. Ideally, the radii γ and δ are sized to support only two panels  4  simultaneously. The ideal spring torque curve indicated by Chart A is most closely achieved by having as few panels simultaneously engage radii γ and δ as possible. Since effective disengagement of adjacent panels will not occur if radii γ and δ are sized to only accept one panel, two panels is optimum. 
         [0033]    The optimal sizing of the radii γ and δ allows for the advantageous reduced force required to operate the door  2 . Larger radii would require increased initial force to hold the panels, thereby causing the spring torque to door torque to become out of balance near the closed position as those panels are no longer traveling within the radii. Larger radii would also increase the height of the stacked panels  4  above the door opening creating the need for additional overhead space. In the preferred embodiment, the radii γ and δ are about three inches to about five inches, and optimally, about four inches. Along with providing the optimal spring torque to door torque ratio, the optimal radii allow the footprint of the panel stack  58  to fit within the current requirements for a typical rolling steel door construction, thereby allowing easy retrofit. 
         [0034]    In operation of a preferred embodiment, to close the overhead door  2  a motor  60  turns a shaft  62  in a direction to unwind a cable  64  from a cable drum  66  attached to the shaft  62 . The bottom panel  48  gravity closes as the cable  64  unwinds. The bottom panel  48  maintains the panel immediately superior to it in the panel stack  58  until the point of transition to the engaged position. As the lip  20  and trough  22  of adjacent panels  4  become engaged, the process begins again as the newly engaged panel maintains its immediately superior panel in the panel stack  58  until the point of transition to the engaged position. The process repeats until all of the panels necessary to close the opening are in place. 
         [0035]    To open the door  2 , the opposite occurs. As the motor  60  turns the shaft  62  winding the cable  64  onto the cable drum  66  the bottom panel  48  is raised thereby raising all the panels above it. As a panel  4  travels through the radii γ and δ, the activation bearings  34  located at each panel end disengage the lip  20  and trough  22  of adjacent panels as the activation bearings  34  ride on the panel guide  38  around the panel bottom edge radius  40 . As each succeeding panel is disengaged it pushes the preceding panel into and forms the panel stack  58 . 
         [0036]    In this manner, the weight of the door  2  decreases as each panel  4  disengages and joins the panel stack  58 . This allows for easier control of the spring torque to door weight ratio. This linear relationship (indicated by Chart A) requires a much smaller motor to provide the lifting torque necessary to operate the door when compared to known technology where the panels cannot separate from one another. 
         [0037]    Because the panels  4  are independent from and unconnected to one another, repair or replacement is easily and quickly accomplished. Returning to  FIG. 6 , in the door open position each independent stacked panel  4  can be slid out the rear of the stack until the damaged panel is retrieved. Once repaired or replaced, the removed panels  4  are easily and quickly replaced within the track. No time is lost to removing hinges or otherwise disconnecting and reconnecting one panel to adjacent panels as required with existing technology. 
         [0038]    Although the present design has been described in connection with specific examples and embodiments, those skilled in the art will recognize that the present design is capable of other variations and modifications within its scope. For example, although a cable lifting mechanism has been described, any motion that provides for raising and lowering the bottom panel is contemplated. These examples and embodiments are intended as typical of rather than in any way limiting on the scope of the present design as presented in the appended claims.