Abstract:
An apparatus and method for releasably mounting access control components for a door lock to a door. A base element is adapted to be mounted to the door. A first wire connector element is mounted to the base element. A mounting element with combustible material attached is provided. A second wire connector element is mounted to the mounting element, and the second wire connector element is releasably connected to the first wire connector element to mount the mounting element to the base element. A spring is provided, and a retainer holds the spring in a loaded state, but in a fire event the retainer may melt, allowing the spring to apply force to the mounting element. Alternatively, an expanding material may apply the force. The force causes the wire connector elements to disconnect and allow the mounting element to separate from the base element.

Description:
FIELD 
     Aspects of the present disclosure may relate to enclosures for electronics, and in particular may relate to access control components for doors. 
     BACKGROUND 
     Achieving fire safety ratings from recognized labs is often required by local code for certain doors. A feature of a fire resistive door assembly that passes a code accepted fire test is that a fire does not ignite from components mounted to the door on an opposite side of a door from a fire. Electronic control components associated with electrical door locks need for their wire harnesses to disconnect from printed circuited (PC) boards in order to pass fire tests such that most of the combustible materials are removed from the surface of a door to avoid a fire on the door. Access control parts, which are often made of plastics and other combustible material, now in general need to be automatically removed from the face of a fire rated door in the event of a fire. Wires, which are generally made of copper, may act as a tether, keeping the access control parts, including combustible materials, attached to the door, even when the plastics that attach parts to the door have melted. 
     SUMMARY 
     Embodiments of a wire disconnection apparatus and method that may be applicable to fire applications may be realized by mounting features provided for access control components for a door lock to a door that will release or eject combustible components from the door prior to igniting, including means for automatically disconnecting wires that may otherwise tether the combustible components to the door. A spring that may be held in a loaded state by a retainer may be released to a free state when at least a portion of the retainer melts, or expandable material may expand, to apply force to cause the wires to separate at connectors. 
     In accordance with an embodiment disclosed herein, an apparatus for releasably mounting access control components for a door lock to a door is provided. The apparatus includes a base element adapted to be mounted to the door. At least one first wire connector element is mounted to the base element. A mounting element is provided. At least one second wire connector element is mounted to the mounting element, and the at least one second wire connector element is releasably connected to the at least one first wire connector element to mount the mounting element to the base element. A spring is provided, and a retainer holds the spring in a loaded state at normal temperatures, where normal temperatures may be considered to be the ambient temperature when there is not fire. The retainer is adapted to be mounted directly or indirectly to the door, and the spring is adapted to bias the retainer in a direction away from the door. 
     In some embodiments, combustible material is attached to the mounting element, and the retainer will lose strength causing the retainer to release the spring from the loaded state above a predetermined temperature that is lower than the temperature at which the combustible material will ignite. The predetermined temperature may be, for example, the melting temperature of the retainer. When released, the spring will extend to apply force to the mounting element to cause the at least one first wire connector element and the at least one second wire connector element to disconnect to allow the mounting element to separate from the base element. In some such embodiments, the loss of strength of the retainer is the result of at least a portion of the retainer melting. 
     In some such embodiments, the base element includes a substantially planar member and the mounting element comprises a substantially planar member. In some such embodiments, the base element comprises a printed circuit board and the mounting element comprises a printed circuit board. In some embodiments and in combination with any of the above embodiments, the spring is a compression spring, a torsion spring, an extension spring, or a leaf spring. In some embodiments and in combination with any of the above embodiments, the retainer includes a plastic, a rubber, a low melting point metal, or any combination thereof that may melt below approximately 500 degrees F. 
     In some embodiments and in combination with any of the above embodiments, the first wire connector element is one of male and female, and the second wire connector element is the other of male and female. In some embodiments and in combination with any of the above embodiments, the first wire connector element and second wire connector element form a mezzanine style connector. In some embodiments, the loss of strength of the retainer is the result of at least a portion of the retainer melting. In some embodiments and in combination with any of the above embodiments, at least one additional spring and at least one additional retainer are provided, with each retainer for holding a respective spring in a loaded state, where each additional retainer is adapted to be mounted directly or indirectly to the door, and each additional spring is adapted to bias a respective retainer in a direction away from the door. 
     In accordance with another embodiment, another apparatus for releasably mounting access control components for a door lock to a door is provided. The apparatus includes a base element adapted to be mounted to the door, and at least one first wire connector element mounted to the base element. A mounting element is provided, with combustible material attached to the mounting element. At least one second wire connector element is mounted to the mounting element, and the at least one second wire connector element is releasably connected to the at least one first wire connector element to mount the mounting element to the base element. A holder is provided that is adapted to be mounted directly or indirectly to the door. An expandable material is disposed between the base element and the mounting element, where the expandable material is capable of undergoing a volume expansion of at least approximately 5% in response to increased temperatures that are less than the ignition temperature of the combustible materials. In some embodiments, a holder adapted to be mounted directly or indirectly to the door is provided. The holder is configured as a piston having a free end and defines an internal region in which the expandable material is disposed, and the free end of the piston applies force to the mounting element in response to the expansion of the expandable material. 
     In some such embodiments, the expandable material will expand to cause force to be applied to the mounting element to cause the at least one first wire connector element and the at least one second wire connector element to disconnect to allow the mounting element to separate from the base element. In some embodiments and in combination with any of the above embodiments, the expandable material comprises wax or an intumescent material. In some embodiments and in combination with any of the above embodiments, the holder is configured as a piston having a free end, where the free end of the piston applies force to the mounting element in response to the expansion of the expandable material. In some embodiments, the first wire connector element and second wire connector element form a mezzanine style connector. 
     In accordance with another embodiment, another apparatus for releasably mounting access control components for a door lock to a door is provided. The apparatus includes at least one first wire connector element, first means for mounting the at least one first wire connector element to the door, at least one second wire connector element releasably connected to the at least one first wire connector element, and second means for mounting combustible material to the at least one second wire connector. Means are provided for urging the second means for mounting away from the first means for mounting when a predetermined temperature is exceeded, causing the at least one first wire connector element and the at least one second wire connector element to disconnect. 
     In some such embodiments, the means for urging includes a spring and a retainer for holding the spring in a loaded state. The retainer is adapted to be mounted directly or indirectly to the door, and the spring is adapted to bias the retainer in a direction away from the door. The retainer will lose strength causing the retainer to release the spring from the loaded state at a predetermined temperature that is lower than the temperature at which the combustible material will ignite. When released, the spring will extend to apply force to the second means for mounting to cause the at least one first wire connector element and the at least one second wire connector element to disconnect to allow the second means for mounting to separate from the first means for mounting. In some such embodiments, the retainer losing strength is caused by at least a portion of the retainer melting; the predetermined temperature may be the melting temperature of the retainer. 
     In some embodiments, the means for urging includes an expandable material disposed between the first means for mounting the at least one first wire connector element to the door and the second means for mounting combustible material to the at least one second wire connector. In response to increased temperature and at a temperature lower than the temperature at which the combustible material will ignite, the expandable material will expand to cause force to be applied to the mounting element to cause the at least one first wire connector element and the at least one second wire connector element to disconnect to allow the mounting element to separate from the base element. In some embodiments, the means for urging further includes a holder adapted to be mounted directly or indirectly to the door, wherein the holder is configured as a piston having a free end and defines an internal region in which the expandable material is disposed, and wherein the free end of the piston applies force to the mounting element in response to the expansion of the expandable material. 
     In accordance with another embodiment, a wire disconnection method for releasably mounting access control components for a door lock to a door is provided. The method includes providing a base element adapted to be mounted to the door, mounting at least one first wire connector element to the base element, providing a mounting element, and mounting at least one second wire connector element to the mounting element. The at least one second wire connector element is releasably connected to the at least one first wire connector element to mount the mounting element to the base element. The method also includes providing means for urging the mounting element away from the base element when a predetermined temperature is exceeded, causing the at least one first wire connector element and the at least one second wire connector element to disconnect. 
     In some such embodiments, providing means for urging includes providing one or more springs, where the force exerted by the one or more springs when released from a loaded state to a free state is greater than the force required to disconnect the first wire connector element and the second wire connector element, and maintaining each spring in a loaded state with a retainer, where each retainer is adapted to be mounted directly or indirectly the door. 
     In some such embodiments, the method further includes attaching combustible material to the mounting element. In response to increasing above a predetermined temperature that is lower than the temperature at which the combustible material will ignite, the one or more retainers loses strength, causing the one or more retainers to release the one or more springs from the loaded state. The one or more released springs extend to apply force to the mounting element to cause the at least one first wire connector element and the at least one second wire connector element to disconnect to allow the mounting element to separate from the base element. In some such embodiments, the retainer losing strength includes at least a portion of the retainer melting. 
     In some embodiments, providing means for urging includes disposing an expandable material between the first means for mounting the at least one first wire connector element to the door and the second means for mounting combustible material to the at least one second wire connector. In response to increased temperature and at a temperature lower than the temperature at which the combustible material will ignite, the expandable material will expand to cause force to be applied to the mounting element to cause the at least one first wire connector element and the at least one second wire connector element to disconnect to allow the mounting element to separate from the base element. In some such embodiments, providing means for urging further includes providing a holder adapted to be mounted directly or indirectly to the door, where the holder defines an internal region in which the expandable material is disposed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a door with access control components mounted thereto in accordance with an embodiment. 
         FIG. 2  is a side elevation view of a door with an embodiment of wire disconnection apparatus for the access control components of  FIG. 1 , with the components mounted to the door. 
         FIG. 3  is a side elevation view of a door with the wire disconnection apparatus of  FIG. 2 , with certain components having been released from the door. 
         FIG. 4  is a front elevation view of a portion of the wire disconnection apparatus of  FIG. 3 , showing the components that may be mounted to the door. 
         FIG. 5  is a section view of a portion of the wire disconnection apparatus of  FIG. 2  taken along line  5 - 5  of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description of embodiments refers to the accompanying drawings, which illustrate specific embodiments. Other embodiments having different structures and operation do not depart from the scope of the present disclosure. 
     Certain terminology is used herein for convenience only and is not to be taken as a limitation on the embodiments described. For example, words such as “top”, “bottom”, “upper,” “lower,” “left,” “right,” “horizontal,” “vertical,” “upward,” and “downward” merely describe the configuration shown in the figures. Indeed, the referenced components may be oriented in any direction and the terminology, therefore, should be understood as encompassing such variations unless specified otherwise. Throughout this disclosure, where a process or method is shown or described, the method may be performed in any order or simultaneously, unless it is clear from the context that the method depends on certain actions being performed first. 
     Referring now to the drawings, in  FIG. 1  an embodiment of access control components is designated at  10 .  FIG. 1  shows a door  12  with the access control components  10  mounted thereto. Also included with the door  12  are an associated deadbolt  14 , a thumb turn  16  to operate the deadbolt  14 , a latch  18 , and a latch operator  20 . An enclosure  24  houses the access control components  10 . In some embodiments disclosed herein and referring to  FIG. 2 , which shows access control components  10  at normal operating temperature, two PC (printed circuit) boards  30 ,  32  may be stacked back to back. The boards  30 ,  32  may take other forms than PC boards; for example, they may be other substantially planar members, or any shape that permits the functionality disclosed herein. 
     The first PC board may be mounted to the door  12 , and may be a form of a base element, or base board  30 , intended to stay mounted to the door  12 . The second PC board may be a form of a mounting element, which may be the main control board  32  for the door lock, and is shown in  FIG. 3  to be detached from the base board  30 , which may occur at elevated temperatures that may result from a fire, as discussed further below. Combustible materials  34  may be attached to or otherwise associated with the main control board  32 . A material may be considered to be “combustible” for the purposes herein if it ignites within the operating temperature of a code accepted furnace, which may be between an ambient temperature, with a lower expected limit of approximately 20 degrees F., to an upper limit of approximately 2,000 degrees F. For example, combustible material may include most standard plastics, rubbers, and electronics such as capacitors or batteries. 
     The base board  30  may have one or more wire connectors  36  for wire harnesses  38  (which generally come from readers, lock bodies, switches, etc.), and should not be connected to combustible materials in order to meet fire safety requirements, although the presence of certain combustible materials may be acceptable, such as wire jackets and other incidental materials. The base board  30  may be rigidly attached to the door and may be designed minimally so that when left behind on the door  12 , it preferably will be resistant to igniting. Between the two boards  30 ,  32  may be male and female connector elements  40 ,  42 , to make connectors  36 , which may be, for example, mezzanine style connectors, which transfer the signals from the harnesses  38  to the main control board  32 . Other types of connectors may be used that may be disconnected by forcing the components apart. 
     A trigger system may include a spring  50  that is in a compressed or “loaded” state, having relatively high potential energy, while at normal temperatures, as shown in  FIG. 2 . Although a compression spring is depicted in  FIGS. 2 and 3 , the depicted spring  50  could be and also schematically represents an appropriately configured torsion spring, extension spring, leaf spring, or the like. “Normal” temperatures could be any temperature less than the ignition temperature of the combustible materials, but might be expected to be in the range of the ambient temperature in the condition when there is not a fire, which may be expected to be from approximately 20 degrees F. to approximately 120 degrees F., as known to one of ordinary skill in the art. The nature of this spring is to act as an ejection system for the main control board  32  and the attached combustible materials  34 . 
     The spring force may be designed to exceed the retention force of the connector  36 . The spring  50  may be held compressed by a plastic holder, fastener, snap, clip, cap, or other device, as shown by retainer  52 . The retainer  52  may be mounted to the base board  30  or to the door  12 , either by being mounted directly to the door  12  or to the door  12  via another part, such as a backplate, and may be rigidly fixed in place. The material of the retainer  52  may be chosen to have a melting temperature lower than the ignition temperature of any of the combustible materials  34  that need to be ejected. This trigger system may be placed between the two boards  30 ,  32  near the wire connector  36 . 
     As shown in  FIG. 3 , in a fire situation and when a spring  50  is used in the trigger system, the door may heat up from the fire  54 , and resulting from the increased temperature may then melt or otherwise reduce the strength of the retainer  52  prior to igniting other material. This may release the spring  50 , causing the spring  50  to extend to its free state, applying force to the main control board  32 , which may cause the connector elements  40 ,  42  to disconnect, allowing the main control board  32  to separate from the base board  30 . The spring  50  may therefore eject  56  the main control board  32  and the combustible materials safely away from the hot door. Although the retainer  52  may be made of a combustible material, it may be expected to melt away from the door or be pushed away by the spring  50 , or to otherwise not have a significant impact. 
     As an alternative to a spring-based trigger system, the trigger system may use the properties of expandable materials. In  FIGS. 2 and 3 , instead of the representation of spring  50 , also schematically represented is expanding material, and the retainer  52  may be considered to indicate a holder, which in one embodiment may be a piston configuration with one cylinder reciprocally received by another cylinder, although other configurations and shapes are possible. In the piston embodiment, one end of the piston may be mounted to the door  12 , directly or indirectly through another part, such as the base board  30  or a base plate. The other end of the piston may slide relative to the mounted end. As the temperature increases above normal, but below the ignition temperature of the combustible materials  34 , the expandable material within the piston may expand, and the piston may extend to apply force to the main control board  32 . Before combustible materials attached to the main control board  32  ignite, the expandable material, through the piston, may apply force to the main control board, causing the connector elements  40 ,  42  to disconnect, allowing the main control board  32  to separate from the base board  30  as in  FIG. 3 . 
     In yet another embodiment schematically represented by  FIGS. 2 and 3 , the expandable material may simply be in disposed between the two boards  30 ,  32 , without being disposed in an internal region of an enclosed holder, and the expandable material may apply force to the main control board  32  to cause the connector elements  40 ,  42  to disconnect. In this embodiment, the expandable material may be, for example, a sheet or piece of intumescent material. 
     The materials of the components may be selected based on melting temperatures of the components, ignition temperature of the combustible materials, and the amount of force required to disconnect the connector elements  40 ,  42 , with the melting temperature of the retainer, or the expansion temperature of the expandable material, as applicable, preferably being well below the ignition temperature of the combustible materials. One material for the spring may be steel, although other materials may be used, so long as the spring will retain strength to apply force when the retainer melts or loses strength. In one embodiment, the spring may be AISI Type 316 stainless steel having, nominally, dimensions of 0.360 inch outside diameter, 0.875 inch long, 0.038 inch wire diameter, and 0.286 inch solid length, with a spring rate of 14 lb./inch, 5.4 active coils, and closed ends. With respect to the boards  30 ,  32 , PC boards are generally not expected to ignite at temperatures to which the door may be heated, such as from ambient temperature (when there is no fire) to approximately 2,000 degrees F. Such a retainer material may be, for example, plastic, rubber, or low melting point metals, which may be expected to melt at least at temperatures below approximately 500 degrees F., and more particularly between approximately 200 to 500 degrees F. In some embodiments, one possible plastic that may be used is UL94V-0 Listed Polycarbonate+ABS Blend (Bayblend FR 3010). 
     An expandable material may be, for example, a material that is capable of undergoing a volume expansion of at least approximately 5% in response to increased temperatures that are less than the ignition temperature of the combustible materials. One example of expandable material is thermal wax, which in general may be expected to expand in volume by approximately 10 to 15% when it melts. Other expandable materials include intumescent materials. Intumescent materials may be chosen based on the amount of pressure they exert during expansion in a restricted space, and may in some embodiments be relatively hard chars that may be produced, for example, with sodium silicates and graphite, or other materials as known to one of ordinary skill in the art. In some embodiments, some intumescent materials start to expand at approximately 250 degrees F. 
       FIGS. 4 and 5  show an embodiment of the portion of the access control components that may be mounted to the door and may remain mounted to the door after wires are disconnected. The base board  30  may be mounted to the door  12  by being mounted to a back plate  60  with screws  62 . The mezzanine connector element  40  and the wire harness connectors  58  for wire harnesses  38  coming from the door  12  are mounted to the base board  30 . The retainer  52  may also be mounted to the door indirectly via the back plate  60 , or could be mounted in some fashion directly to the door  12 . The retainer  52  in this embodiment may be formed as a cap that defines an annular space in which the compression spring  50  may be disposed. 
     The spring  50  is compressed or loaded in  FIGS. 4 and 5 . The portion of the retainer  52  that defines the interior wall of the annular space may define another central opening that is itself threaded and receives a screw  64 . This screw  64  mounts the retainer  52  to the back plate  60 . As described above, when the retainer loses strength, which may occur by the retainer  52  or a portion of the retainer  52  melting, the spring  50  may extend to an uncompressed or unloaded, free state, applying force to the main control board  32  to disconnect the mezzanine style connector  36  or connectors. Also as described above, the spring  50  and the retainer  52  may be replaced with other types of springs and retainers, or an arrangement for using expandable material to apply the disconnection force, such as with a piston in which expandable material is disposed. A piston preferably may be made of a material that does not melt before the expandable material expands to apply the disconnection force, as known to one of ordinary skill in the art, for example, steel or stainless steel. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. Additionally, comparative, quantitative terms such as “less” or “greater” are intended to encompass the concept of equality, thus, “less” can mean not only “less” in the strictest mathematical sense, but also, “less than or equal to.” 
     Although specific embodiments have been illustrated and described herein, those of ordinary skill in the art appreciate that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiments shown and that the invention has other applications in other environments. This application is intended to cover any adaptations or variations of the present invention. The following claims are in no way intended to limit the scope of the invention to the specific embodiments described herein.