Abstract:
A release mechanism for protecting a sectional door under impact allows one or more door panels to breakaway from its guide track without damaging the door. The release mechanism includes a snap-in pin that can be selectively repositioned to provide various operating modes. Examples of operating modes include unidirectional release, bi-directional release, and a disabled mode. In some cases, the breakaway threshold is greater in one direction than another. In the disabled mode, the release mechanism is not meant to release. Some embodiments include a door locking mechanism that still allows the release mechanism to operate.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The subject invention generally pertains to sectional doors and more specifically to a release mechanism for such a door.  
           [0003]    2. Description of Related Art  
           [0004]    A sectional door typically includes a series of panels whose adjacent horizontal edges are each pivotally connected by a row of hinges. As the door opens or closes, the door panels travel along two lateral tracks that in one configuration curve between horizontal and vertical. To close the door, the tracks guide the panels to a vertical position. When the door opens, the hinges allow the panels to curve around onto horizontal sections of the tracks, where the door panels store horizontally overhead. In other configurations, the sectional door maintains a generally vertical, planar configuration and is stored more directly above the doorway. Such doors, regardless of their configuration, can be powered up or down or can be manually operated. To ease the operation of the door, a torsion spring is often used to offset the weight of the door panels. Sectional doors are commonly used as residential garage doors; however, they are also often used in warehouses and other industrial buildings.  
           [0005]    When used in high-traffic industrial applications, sectional doors are very susceptible to being struck by large trucks, trailers, forklifts and other vehicles passing through the doorway. There are different reasons why vehicles collide with doors. One of the more common causes is a door&#39;s torsion spring becoming weak with age or not being properly preloaded. This can allow a door to droop down into the doorway from a fully open position or not open fully at all. In such cases, an upper edge of a vehicle traveling through the doorway may strike the lower portion of the drooping door, which can damage one or more door panels, as well as damage door-mounting hardware, such as hinges, rollers and track.  
           [0006]    Doors are also often installed adjacent to a dock leveler of a loading dock. When the door is closed, such doors can be damaged as material handling equipment stage loads on the dock leveler. For instance, a forklift may accidentally push a load up against the door.  
           [0007]    Consequently, some doors are provided with some type of breakaway feature that allows a door to give way to a collision without being damaged. For example, a sectional door described in U.S. Pat. No. 5,727,614 includes a track-following roller that can break away from its mounting bracket in reaction to a collision. After the collision, the roller can be reattached to the bracket. The breakaway device, however, has its limitations. Upon breaking away, the roller can completely separate from the mounting bracket, thus an impact could throw the roller where it may be difficult to find. This is particularly true for a loading dock door that is installed adjacent to a dock leveler. In such cases, the roller may fall into a pit that is underneath a conventional dock leveler or fall into some snow that may be just outside the building. It also appears that the &#39;614 device breaks away at a predetermined force, which cannot be readily adjusted or altered once the door is installed. Depending on the application, it may be desirable to have a door that breaks away in one direction easier than another. For instance, for heavier doors, it may be desirable to have a higher breakaway force in one direction (from outside to inside), so that the door does not break away under its own weight when fully open and stored overhead. It some cases, for example, it may be beneficial to have a door whose breakaway feature only acts in one direction. In windy areas, it may be better to have a door that only breaks away in an outward direction to avoid the door giving way to strong winds.  
           [0008]    Another breakaway device, shown in U.S. Pat. No. 6,039,106 does include a means for adjusting the breakaway force. The breakaway force is adjusted by turning a setscrew, which adjusts the pressure that a spring-loaded plunger exerts against a detent of a track-following guide member. Under sufficient breakaway force, the guide member is able to swing its detent out from underneath the force of the plunger; however, the guide member does not completely separate from the plunger. The swinging motion also releases the guide member out from within the track, which releases the door to avoid damage. Although the device has an adjustable breakaway, it appears that the breakaway force is the same in both directions and that the device cannot be readily locked to disable the breakaway feature.  
           [0009]    Other examples of breakaway mechanisms are shown in U.S. Pat. Nos. 5,392,836 and 6,053,237. These devices; however, share some of the same limitations of the other breakaway devices that have already been discussed.  
         SUMMARY OF THE INVENTION  
         [0010]    In order to provide a versatile breakaway device for a sectional door, a release mechanism includes a first member for releasably coupling a track-following guide member to a bracket connected to the door. The first member may be able to snap into and out of the guide member to allow the guide member to move between an operative position where the guide member engages the track and a dislodged position where the guide member separates from the track, or the first member may engage or disengage the guide member in other ways.  
           [0011]    In some embodiments, the guide member includes a roller.  
           [0012]    In some embodiments, the release mechanism releases easier in one direction than another.  
           [0013]    In some embodiments, the release mechanism is selectively reconfigureable to a releasable mode and a non-releasable mode.  
           [0014]    In some embodiments, the release mechanism is selectively reconfigureable by selectively inserting a pin in different holes.  
           [0015]    In some embodiments, the release mechanism includes a releasable pin that is U-shaped.  
           [0016]    In some embodiments, the release mechanism is capable of being reset to its operative position without the use of tools.  
           [0017]    In some embodiments, the first member and the guide member completely separate from each other upon moving from the operative position to the dislodged position.  
           [0018]    In some embodiments, the guide member is pivotal about the retaining member. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    [0019]FIG. 1 is a front view of one embodiment of an overhead-storing sectional door in a partially open position, with the door being viewed from inside a building and looking out.  
         [0020]    [0020]FIG. 2 is a cross-sectional view taken along line  2 - 2  of FIG. 1.  
         [0021]    [0021]FIG. 3 is a front view of one example of a door panel hinge.  
         [0022]    [0022]FIG. 4 is an end view of the hinge of FIG. 3.  
         [0023]    [0023]FIG. 5 is an end view of one embodiment of a release mechanism.  
         [0024]    [0024]FIG. 6 is a front view of FIG. 5.  
         [0025]    [0025]FIG. 7 is a top view of a guide member of the release mechanism shown in FIG. 6.  
         [0026]    [0026]FIG. 8 is a cross-sectional view taken along line  8 - 8  of FIG. 1, showing a release mechanism is an operative position.  
         [0027]    [0027]FIG. 9 is similar to FIG. 8, but with the release mechanism in a dislodged position.  
         [0028]    [0028]FIG. 10 is similar to FIG. 8, but with the pins of the release mechanism in a different position.  
         [0029]    [0029]FIG. 11 is similar to FIG. 10, but with the release mechanism in a dislodged position.  
         [0030]    [0030]FIG. 12 is a top view of a guide member that provides a release mechanism with bi-directional breakaway.  
         [0031]    [0031]FIG. 13 is a perspective view of a retainer being inserted into a block of a guide member to provide unidirectional breakaway.  
         [0032]    [0032]FIG. 14 is similar to FIG. 13, but with the retainer being inserted into the block so as to disable the breakaway feature.  
         [0033]    [0033]FIG. 15 is a top view of the block of FIGS. 13 and 14 with a roller inserted in the block.  
         [0034]    [0034]FIG. 16 is similar to FIG. 8, but of another release mechanism in an operative position.  
         [0035]    [0035]FIG. 17 is the release mechanism of FIG. 16, but with the release mechanism in a dislodged position.  
         [0036]    [0036]FIG. 18 is a cross-sectional view taken along line  18 - 18  of FIG. 16.  
         [0037]    [0037]FIG. 19 is similar to FIG. 1, but with the door closed.  
         [0038]    [0038]FIG. 20 is a cross-sectional view taken along line  20 - 20  of FIG. 19 (with some features pertaining to the rollers and release mechanism omitted for clarity).  
         [0039]    [0039]FIG. 21 is a cross-sectional view taken along line  21 - 21  of FIG. 1 (with some features pertaining to the rollers and release mechanism omitted for clarity). 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0040]    A sectional door  10 , shown partially open in FIGS. 1 and 2, includes a series of door panels  12 ,  14 ,  16  and  18  that are interconnected along their adjacent horizontal edges by hinges  20 . As door  10  opens or closes relative to a doorway  22  defined by a wall  23 , guide members  24  guide the movement of the panels along two lateral tracks  26  and  28 . In this example, tracks  26  and  28  curve between horizontal and vertical; however, it is well within the scope of the invention to have tracks  26  and  28  run generally linearly or only curve slightly, so that when the door opens, the door panels move above doorway  22  while remaining in a generally vertical or slightly angled orientation. To close door  10 , the vertical sections of tracks  26  and  28  guide the panels to a vertical position across doorway  22 , as indicated by the positions of panels  12  and  14 . When door  10  opens, hinges  20  allow the panels to curve around onto the horizontal sections of tracks  26  and  28 , where the door panels store horizontally overhead, as indicated by the position of panel  18 .  
         [0041]    The actual structure of panels  12 ,  14 ,  16  and  18  can vary from one door to another, vary among panels of the same door, or be the same for each panel of the same door and still remain well within the scope of the invention. A door panel according to this embodiment comprises a foam core  30  protected by a tough outer shell  32 . Shell  32  may comprise a rectangular metal frame that supports two parallel face panels. The metal frame can also serve as a strong base to which door hardware can be mounted, such as hinges  20  and pliable seals  34 . Seals  34  help seal the gap between adjacent door panels. In some cases, hinges  20  comprise a hinge pin  36  that pivotally couples two U-shaped hinge plates  38  and  40 , as shown in FIGS. 3 and 4. Hinge plates  38  and  40  can be fastened to the edge of a door panel by way of fasteners  42 . It should be noted; however, that the present invention can be applied to doors with other types of hinges; different types of seals (or no seals); and door panels of various other designs, such as those that are solid or hollow.  
         [0042]    The primary focus of the invention is to provide a sectional door with a feature that helps protect a door that may be subjected to excessive forces, such as forces that occur during an impact. Such a feature can be provided by a release mechanism  44  that allows one or more door panels (or even just part of one panel) to move away from its guide tracks in response to a sufficient breakaway force being exerted against the door.  
         [0043]    In a preferred embodiment, release mechanism  44  includes a U-shaped bracket  46  that attaches adjacent an edge (preferably to the frame) of a panel (e.g., panel  12 ) by way of a fastener  48 , as shown in FIGS. 5 and 6. Between two flanges  50  and  52 , bracket  46  supports guide member  24 , which in this case, includes a nylon block  54  that supports a shaft  56  of a roller  58  (or some other type of track-guided element, not limited to only those that roll). In some cases, the axial position of shaft  56  can be limited or restrained by some feature such as a conventional cotter pin, C-clip, E-clip, push nut, sleeve  102  (to be explained further with reference to FIG. 15) or in the case of the preferred embodiment, a setscrew  60  that clamps against the side of shaft  56 .  
         [0044]    To render mechanism  44  releasable under impact (or some other sufficient force applied in the direction indicated by arrow  62  of FIG. 9), block  54  is releasably coupled to bracket  46  in a manner that allows guide member  24  to move from an operative position of FIG. 8 to a dislodged position of FIG. 9. At the same time, block  54  is also coupled to bracket  46  such that the guide member  24  stays attached to the panel even after moving to the dislodged position. Toward that end for release mechanism  44 , elongated elements, such as pins  64  and  66  couple block  54  to bracket  46 . The term, “pin” refers to any elongated element, examples of which include, but are not limited to, a clevis pin, roll pin, cotter pin, dowel, screw, rivet, nail, threaded rod, etc. Although pins  64  and  66  are used in a preferred embodiment, other elongated elements that do not necessarily resemble a pin are also well within the scope of the invention. Pin  64  extends through two aligned holes in flanges  50  and  52 , with a portion  64 ′ (FIG. 6) of pin  64  extending through a hole  68  (FIG. 7) in block  54 . In this way, guide member  24  is pivotally mounted to the panel. Alternatively, opposite ends of pin  64  can be welded or otherwise attached to flanges  50  and  52  without the use of holes in the flanges of bracket  46 . In a similar manner, pin  66  also extends through two aligned holes in flanges  50  and  52 ; however, to provide release mechanism  44  with the ability to break away, a portion  66 ′ (FIG. 6) of pin  66  is received within a slot  70  in block  54 . In this way, a releasable coupling is created between guide member  24  and panel  12 , wherein pin  66  is a first member adapted for selective engagement with the guide member  24  to form a releasable coupling that allows the guide member to move from the engaged to the dislodged position by virtue of complete separation between guide member  24  and pin  66  in response to a force exerted in direction  62 , which is generally perpendicular to panel  12 . A neck  72  of slot  70  is reduced in width to allow pin  66  to selectively engage (e.g., snap in or out) with block  54 , as block  54  swings about pin  64  between the operative and dislodged positions. Pin  64  thus forms a second member that fastens guide member  24  to panel  12  such that guide member  24  stays with panel  12  even after it has moved to the dislodged position.  
         [0045]    Disengagement between pin  64  and slot  70  occurs when an impact force applied against and generally perpendicular to panel  12 , as indicated by arrow  62 , is reacted by a counter force that track  28  exerts against roller  58  in an opposite direction. The counter force being spaced apart from pin  64  produces a clockwise (as viewed in FIG. 9) torque on block  54  about pin  64 . The torque forces block  54  to rotate about pin  64  and away from pin  66  (thus separating therefrom) when the force applied along direction  62  is sufficient release pin  66  from slot  70 .  
         [0046]    To return release mechanism  44  from its dislodged position to its operative position, panel  12  is moved back to its normal operating position adjacent track  28 , roller  58  is reinserted into track  28 , and pin  66  and block  54  are reconnected. To reconnect pin  66  and  54 , the two can be snapped back together or pin  66  can be lifted or lowered lengthwise back into slot  70  once slot  70  is realigned with the holes that receive pin  66 . The terms, “snap” and “snapped” refer to the engagement or disengagement of two elements, wherein at least one of the elements resiliently deforms as the two elements engage or disengage.  
         [0047]    Although pins  64  and  66  are preferably non-frangible, in some cases it may be desirable to make pin  64  (and/or pin  66 ) frangible. Pin  64  when frangible could release block  54  from bracket  46  under a predetermined force that is sufficient to break pin  64  but not be so great as to significantly damage other parts of release mechanism  44 . Thus, a frangible pin  64  can serve as a sacrificial piece that is relatively inexpensive and easy to replace after panel  12  is dislodged. To render pin  64  frangible, pin  64  can be made of a relatively weak material or be sized to limit its strength.  
         [0048]    To selectively disable the breakaway feature of release mechanism  44 , pin  66  is removed from slot  70  and the corresponding holes of bracket  46 , and reinserted through another set of holes  74  and  76  that are in bracket  46  and block  54 , respectively, as shown in FIG. 10.  
         [0049]    To allow a door panel to move in response to an impact from either direction (i.e., from inside to outside, as indicated by arrow  62  of FIG. 9, or from outside to inside, as indicated by an arrow  76  of FIG. 11), a release mechanism  44 ′ can be provided with a modified block  78 , as shown in FIG. 12. Block  78  is similar to block  54 ; however, a slot  80  in block  78  replaces hole  68  of block  54 . Slots  70  and  80  are similar in that they both allow their respective pins  66  and  64  to selectively and engage and release block  78 . Sufficient force acting against a door panel in the direction of arrow  77  can force block  78  to swing about pin  66  and break away from pin  64 , or sufficient force acting in an opposite direction (direction  62  of FIG. 9) can force block  78  to swing about pin  64  and break away from pin  66 . Thus, release mechanism  44 ′ has two pivot points: pin  64  and  66 . Moreover, pin  64  in this embodiment forms a second member that is adapted for selective engagement with the guide member. Thus, both pins  64  and  66  are capable of pivotally mounting guide member  24  to panel  12  when breakaway or release occurs about the other pin, while at the same time being capable of themselves selectively disengaging from guide member  24  for an appropriately directed breakaway force. To provide one or more guide member  24  with sufficient clearance to swing to the position of FIG. 11, door panel  12  and/or the other door panels are provided with a notched out section  79 .  
         [0050]    In some cases, pin  64  and slot  80 , and pin  66  and slot  70  may be sized differently to provide release mechanism  44 ′ with a breakaway threshold that is greater in one direction than the other. In other cases, the dimensions of pins  64  and  66  and their fit within their respective slots  80  and  70  may be identical and still provide a threshold differential or breakaway threshold that is greater in direction  77  than in direction  62  by virtue of track  28  being closer to pin  66  than to pin  64 , which provides a leverage advantage to a force acting in direction  62  (opposite to direction  77 ). To provide an equal breakaway threshold in both directions, the engagement between pin  64  in slot  80  may be made loser than the engagement between pin  66  and slot  70  to compensate for the threshold differential brought on by pins  64  and  66  being at an unequal distance away from track  28 .  
         [0051]    Although pins  64  and  66  have been described as individual pins, the two pins can be joined or formed as a unitary U-shaped retainer  82 , as shown in FIGS.  13 - 15 . Retainer  82  comprises a pin  84  and a pin  86  that are connected by a cross member  88 . Retainer  82  can be used in conjunction with a block  90  that is similar to blocks  54  and  78 . The distance between a hole  92  and a slot  94  is preferably the same as the distance between a hole  96  and hole  92 , with the layout of slot  94  and holes  92  and  96  corresponding to a matching pattern of three holes in a bracket similar to that of bracket  46 . Inserting retainer  82  in the position of FIG. 13 (i.e., pin  84  in hole  92 , and pin  86  in slot  94 ) provides a release mechanism that operates like release mechanism  44  of FIG. 9. And inserting retainer  82  in the position of FIG. 14 (i.e., pin  84  in hole  92 , and pin  86  in hole  96 ) disables the breakaway feature to provide an operating mode similar to release mechanism  44  of FIG. 10. A hole  98  for a setscrew  100  is positioned so as not to interfere with hole  96 . Sleeve  102 , as shown in FIG. 15, extends over the shaft of the guide roller to reinforce the shaft and help establish a certain spacing between the roller and block  90 .  
         [0052]    As a further illustration of the inventive release mechanism, an alternative embodiment including release mechanism  44 ″ is provided, as shown in FIGS.  16 - 18 . Release mechanism  44 ″ includes a guide member  24 ′ whose shaft  56 ′ is pivotally coupled to a door panel  12 ′ by way of a pin  104  that that can be connected to panel  12 ′ directly or connected indirectly through a bracket  106 . With sufficient force acting in direction  62 , guide member  24 ′ pivots about pin  104  to disengage or separate from a releasable bracket  108 , which is attached to panel  12 ′ at a position between pivot pin  104  and the portion of guide member  24 ′ engaged with the track. In some embodiments, releasable bracket  108  is a snap-action device; however, bracket  108  is schematically illustrated to encompass any device that is adapted for selective engagement (FIGS. 16 and 18) and disengagement (FIG. 17) with guide member  24 ′. Releasable bracket  108  thus forms a first member adapted for selective engagement with the guide member  24 ′ in a similar sense to the way that pin  66  of the embodiment of FIG. 9 is adapted for selective engagement with guide member  24 . That is, the concept of adapted for selective engagement can encompass the situation where the guide member is yieldable relative to a generally rigid first member (as in slot  70  yielding relative to the generally rigid pin  66  in FIG. 9) and the situation where the guide member is generally rigid, and it is the first member that yields relative to the guide member (as in releasable bracket  108  yielding relative to generally rigid shaft  56 ′ of guide member  24 ′ in FIGS.  16 - 18 ). In all of the embodiments described so far, then, the guide member is pivotally mounted to the panel, and a first member is provided that is adapted for selective engagement with the guide member to selectively place the guide member in an operative position and a dislodged position, with the first member and guide member being separated in the dislodged position.  
         [0053]    To allow door  10  to be held in a closed position without limiting the breakaway ability of a release mechanism, door  10  is provided with a latch mechanism  110 , as shown in FIGS. 1, 2 and  19 - 21 . Latch mechanism  110  includes a base  112  whose position is stationary and a traveling bar  114 , which is attached to panel  14 . A pin  116  rotatably couples an arm  118  to base  112 , so arm  118  that can swing over and thus capture traveling bar  114  to inhibit door  10  from opening, as shown in FIGS. 19 and 20. Even though arm  118  engaging bar  114  inhibits panel  14  from rising, door panel  14  can still be forcibly dislodged in direction  62 , because panel  14  (as it becomes dislodged) can move bar  114  from the restraint of arm  118  by moving arm  144  in direction  62 .  
         [0054]    To release door  10  under normal, non-breakaway conditions, arm  118  can swing away from bar  114  and preferably swing over and onto a stationary bar  120  that extends from base  112 , as shown in FIGS. 1, 2 and  21 . To inhibit arm  118  from accidentally swinging off bars  114  or  120 , a distal end of each bar  114  and  120  can be provided with a hole to receive the shackle of a padlock  122 , whereby padlock  122  can hold arm  118  at either selected location: on bar  114  or  120 .  
         [0055]    Although the invention is described with reference to a preferred embodiment, it should be appreciated by those skilled in the art that various modifications are well within the scope of the invention. Therefore, the scope of the invention is to be determined by reference to the claims that follow.