Patent Publication Number: US-8522853-B2

Title: Closure assemblies for fire doors, fire doors including such closure assemblies and methods of locking fire doors

Description:
TECHNICAL FIELD 
     The invention relates to fire doors. In particular, embodiments of the invention relate to closure assemblies for fire doors, fire doors including such closure assemblies and methods of locking fire doors. 
     It is common practice in many public buildings, such as churches and hotels, to use folding doors as room dividers. In open, folded condition, the doors fit out of the way into compartments in a wall of a large room, and are extended across the room when division of the large room into smaller rooms is desired. While initially such doors were used merely as dividers, some are now constructed to meet certain fire resistant specifications and can be used as fire doors in buildings. Recently, such doors have begun to be used primarily as fire doors in condominiums, apartment and office building lobbies. When used as fire doors, the doors are normally open and, when a fire is sensed, are motor driven and automatically close. The doors themselves are not mechanically latched together since they have to remain manually operable for a period of time during a fire to be easily opened by people fleeing the fire. When used as fire doors, if a single door, the leading edge of the lead post assembly of the door generally fits into a receiving recess at the opposite side of the room from where the door is stored. If the door is a double or biparting door, a section of the door is stored on each of opposite sides of a room and the door comes together intermediate the sides of the room. In such an instance, one door section has the normal male leading edge on its lead post assembly that fits into a receiving female recess in the lead post assembly of the other door section. The lead post assemblies of such doors are generally constructed of a single metal channel or of metal pieces connected directly together along large contact areas such that heat is readily transmitted from one side of the lead post assembly to the other causing the entire lead post assemblies to get very hot. Further, especially with biparting doors, while the seal between the door sections is tight initially, after being subjected to intense fire heat of a period of time the lead post assemblies tend to warp and the doors come apart. This is not acceptable under many fire standards. 
     In view of the foregoing, improved closure assemblies for fire doors, fire door assemblies including such closure assemblies and methods of locking fire doors would be desirable. 
     BRIEF SUMMARY 
     In some embodiments, a closure assembly for a fire door may include a first lead post having a longitudinal cavity located therein and an opening extending through a wall of the first lead post into the longitudinal cavity. Additionally, a locking member may be positioned within the longitudinal cavity, and the locking member may be configured to obstruct the opening into the longitudinal cavity upon reaching a predetermined temperature. 
     In additional embodiments, a method of locking a fire door may include inserting an extending member comprising an enlarged end portion through an opening and into a cavity of a lead post, and heating the lead post to a predetermined temperature to cause a portion of a locking member enclosed within the cavity to move from a first position to a second position overlapping a portion of the opening and obstructing the opening to prevent the enlarged end portion of the extending member from being removed from the cavity of the lead post. 
     In yet additional embodiments a fire door may include a folding door section, a lead post at a leading end of the folding door section, a longitudinal cavity located within the lead post, and an opening into the longitudinal cavity. Additionally, the fire door may include a locking member positioned within the longitudinal cavity of the lead post, and the locking member may be configured to obstruct the opening into the longitudinal cavity upon reaching a predetermined temperature. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a perspective pictorial view of a room including a biparting fire door assembly including a closure assembly according to an embodiment of the present invention. 
         FIG. 2  shows a horizontal cross-sectional view of the biparting fire door of  FIG. 1  contained in recesses within walls of the room. 
         FIG. 3  shows a horizontal cross-sectional view of a single parting fire door assembly including a closure assembly according to an embodiment of the present invention. 
         FIG. 4A  shows a horizontal cross-sectional detail view of the closure assembly of the fire door of  FIGS. 1 and 2  in a separated, open configuration. 
         FIG. 4B  shows a horizontal cross-sectional detail view of the closure assembly of  FIG. 4A  in a closed configuration. 
         FIG. 5A  shows an isometric pictorial view of a locking member of the closure assembly of  FIGS. 4A and 4B . 
         FIG. 5B  shows a front view of the locking member of  FIG. 5A . 
         FIG. 5C  shows a bottom view of the locking member of  FIGS. 5A and 5B . 
         FIG. 6A  shows a vertical cross-sectional detail view of the closure assembly of the fire door of  FIGS. 1 and 2  in a separated, open configuration. 
         FIG. 6B  shows a vertical cross-sectional detail view of the closure assembly of  FIG. 6A  in a closed configuration. 
         FIG. 6C  shows a vertical cross-sectional detail view of the closure assembly of  FIGS. 6A and 6B  in a closed and locked configuration. 
     
    
    
     DETAILED DESCRIPTION 
     The illustrations presented herein are not meant to be actual views of any particular device or system, but are merely idealized representations that are employed to describe various embodiments of the present invention. It is noted that elements that are common between figures may retain the same numerical designation. 
     As shown in  FIG. 1 , a room  10 , such as a building lobby, may include one or more fire doors that may be comprised of one or more folding door sections. 
     For example, a biparting fire door  12  may include a first folding door section  14  and a second folding door section  16 . Each folding door section  14  and  16  may include a plurality of panels  18  and each panel  18  of the plurality of panels  18  may be coupled to one or more adjacent panels  18  of the plurality of panels  18  with a hinge member  20 . Furthermore, each folding door section  14  and  16  may be supported and suspended from an overhead track  22  by wheeled support structures (not shown). In view of this, each folding door section  14  and  16  may be configured to extend and retract along the overhead track  22 . 
     The fire door  12  may also include a closure assembly  24  to seal the fire door upon closure and maintain a seal during a fire event. In some embodiments, the closure assembly  24  includes a first lead post assembly, such as a male lead post assembly  26  of the first folding door section  14 , and a second lead post assembly, such as a female lead post assembly  28  of the second folding door section  16 . 
     In the case of fire, the room  10  may be separated by the fire door  12  into two or more rooms. In view of this, the fire door  12  may be utilized to separate certain parts of a building, for example a building entrance may be separated from elevators, such as to prevent the spread of a fire and/or to facilitate a safe evacuation of personnel from the building. 
     Generally, when folding doors are installed as fire doors, the doors are motor driven so that in the event of a fire, which may be sensed by a fire sensing system, the doors automatically close to provide a desired fire barrier. The use of the fire doors to separate a building entrance from elevators is merely an example of where such doors are commonly used, and the doors may be used generally in any location where desired or required by fire codes. 
     When open, the folding door sections  14  and  16  are folded and may be housed out of the way in recesses  30  and  32  in walls  34  and  36  respectively (as further shown in  FIG. 2 ). Upon activation, such as by an automated fire detection system or by an operator, the folding door sections  14  and  16  may be carried upon and distributed along the overhead track  22 . The male lead post assembly  26  may form an extended leading end  38  for the first folding door section  14 , while the female lead post assembly  28  of the second folding door section  16  may form a receiving groove  40  for the leading end  38  of the male lead post assembly  26 ,  26  when the first and second folding door sections  14  and  16  come together in a closed position; this may create a closure for the fire door  12 . Additionally, the closure assembly  24  includes locking devices (shown in  FIGS. 4A through 6C ) that may lock the lead post assemblies  26  and  28  together upon reaching a predetermined temperature, which may prevent the severe heat from a fire from causing the lead post assemblies  26  and  28  to separate, such as due to warping. 
     As shown in  FIG. 2 , the first and second folding door sections  14  and  16  may be coupled to and stowed within respective recesses  30  and  32  formed within walls  34  and  36  of the room  10 , which may optionally include hinged covers  42 . As shown in the cross-sectional view of  FIG. 2 , the male lead post assembly  26  of the first folding door section  14  is sized and configured to fit at least partially within the receiving groove  40  of the female lead post assembly  28  of the second folding door section  16  to form a closure when the folding door sections  14  and  16  are fully extended. Also, while  FIG. 1  shows a straight overhead track  22 , in some embodiments the overhead track  22  may be curved, and the door  12 , when closed, may extend in an arcuate line between walls  34  and  36  of the room  10 . 
     While  FIGS. 1 and 2  show two folding door sections  14  and  16 , which form what is referred to as a biparting door  12 , in many instances, depending upon the length of door needed, a single door section may be used to stretch along the entire length of a track from wall to wall to form a single parting fire door  44  as shown in  FIG. 3 . In such an instance, a door section  46  may have a male lead post assembly  48 , similar to that described with reference to the male lead post assembly  26  first folding door section  14  of the biparting fire door  12 , which may mate with a receiving groove  50  of a striker assembly  52  mounted in a recess in a wall  54  to which the door  44  extends. As shown, the receiving groove  50  may be formed by the striker assembly  52 , which may be made of steel or other suitable material and dimensioned to fit within a larger recess formed in the wall  54 . In addition, while not illustrated, those of ordinary skill in the art will recognize that the receiving groove  50  may be positioned on the single parting fire door  44  and the male lead post assembly  48  may be positioned in the recess in the wall  54 . 
     As previously mentioned, when the temperature on one side of a folding fire door gets hot, such as due to a fire, there is a possibility that the lead posts will warp and may separate. To prevent this separation, a locking device may be provided to mechanically lock the doors together. Such mechanical locking is not always desirable, however, for example, when people may be fleeing the fire and must open the door to escape. In view of this, the present invention provides a temperature-sensitive locking apparatus that may mechanically lock the male and female lead post assemblies together only when the temperature on the fire side of the door reaches a predetermined temperature. This predetermined temperature may be less than the temperature that causes warping of the lead posts to ensure that the lead posts are locked by the time they reach warping temperature, but may also be sufficiently high so there could no longer be life trying to escape from the fire. For example, the predetermined minimum temperature may be about 500 degrees F. Embodiments of closure assemblies for fire doors including such locking devices are shown in  FIGS. 4A through 6C . 
     As shown in the detail cross-sectional view of the closure assembly  24  of the fire door  12  illustrated in  FIG. 4A , the male lead post assembly  26  of the first folding door section  14  may include a central post  56  which defines a longitudinal cavity  58  therein. For example, the central post  56  may be a steel rectangular tube, having a generally rectangular cross-section, which extends vertically along substantially the entire length of the extended leading end  38  of the first folding door section  14 . An opening  60  (FIGS.  1  and  6 A- 6 C) extends into the longitudinal cavity  58 , such as through a wall  62  at the leading end of the central post  56 . 
     The female lead post assembly  28  of the second folding door assembly section  16  may include a central post  64 , which may be located at the base of the receiving groove  40 . The central post  64  of the female lead post assembly  28  may be formed of an elongated member that extends substantially along the length of the receiving groove  40  and may provide structural stability to the female lead post assembly  28 . For example, the central post  64  may be a rectangular tubular member, having a generally rectangular cross-section, which may be made of steel or another suitable material. Additionally, the female lead post assembly  28  may include an extending member  66  located within the receiving groove  40  and attached to the central post  64 . The extending member  66  may be additionally sized and located to extend through the opening  60  and into the cavity  58  of the central post  56  of the male lead post assembly  26  when the folding door sections  14  and  16  are extended and the leading end  38  of the male lead post assembly  26  is positioned within the receiving groove  40  of the female lead post assembly  28  (as shown in  FIG. 4B ). For example, the opening  60  of the male lead post assembly  26  may be located at or near the center of the leading end  38  of the male lead post assembly  26  and the extending member  66  may be located at or near the center of the receiving groove  40  of the female lead post assembly  28 . The extending member  66  may include an enlarged end portion  68  (e.g. a head) and a recessed portion  70  (e.g. a shank), and the enlarged end portion  68  may have a diameter D 1  that is larger than a diameter D 2  of the recessed portion  70 . As a non-limiting example, the extending member may be a bolt, such as one of a carriage bolt, a hex bolt, and a shoulder bolt. The recessed portion  70  of the extending member  66  may comprise a portion of the shank of a bolt and the enlarged end portion  68  of the extending member  66  may comprise the head of the bolt. The enlarged end portion  68  of the extending member may be sized and shaped similar to the opening  60  in the male lead post and a diameter D 1  that is smaller than a diameter D 3  of the opening  60  ( FIG. 6A ) to allow the passage of the enlarged end portion  68  through the opening  60 . For example, the opening  60  may be generally cylindrical in shape, having a generally circular cross-section. Likewise, the opening  60  may be sized just larger than the enlarged end portion  68  of the extending member  66 , which may allow a relatively small opening  60  in the male lead post assembly  26  for safety and aesthetic reasons. For example a relatively small opening  60  may be less visible and may reduce the risk of foreign objects being inserted into the opening  60  and hindering the proper operation of the closure assembly  24 . 
     A locking member  72  may be positioned within the cavity of the male lead post, and at least a portion of the locking member  72  may be positioned above the opening  60  within the central cavity  58 . In view of this, the locking member  72  may be completely enclosed within the central cavity  58  of the central post  56  of the male lead post assembly  26 , and may not be visible from the outside. In one embodiment, as shown in  FIGS. 5A-5C , the locking member  72  may be made from a rectangular tube, such as a square tube, which may have a generally rectangular cross-section, such as a square cross-section, made of steel or another suitable material. The locking member  72  may have a bottom end  74  having a locking feature  76  formed therein. For example, the locking feature  76  may be cut into a tube, such as by a milling machine. The locking feature  76  may comprise a tapered portion  78  and a slot  80 . The tapered portion  78  may extend from the bottom end  74  of the locking member  72  to the slot  80 . The slot  80  may be defined by a width W that is larger than the diameter D 2  defining the recessed portion of the extending member  66  and smaller than the diameter D 1  defining the enlarged end portion  68  of the extending member  66 . 
     As shown in  FIG. 6A , a wall  82  of the locking member  72  having the locking feature  76  formed therein may be positioned adjacent to the wall  62  at the leading end of the central post  56  of the male lead post assembly  26 , having the opening  60  formed therein, and the slot  80  of the locking feature  72  may be positioned above the opening  60 . Additionally, a fusible link  84  may be attached to the locking member  72  and to the central post  64  of the male lead post assembly  26  and may support the locking member  72  within the central post  64 . The fusible link  84  may include a first member  86  attached to the locking member  72 , a second member  88  attached to the central post  64 , and a fusible material  90  positioned between the first member  86  and the second member  88 . For example, the fusible material  90  may be a metal alloy configured to melt at a predetermined temperature, such as about 500 degrees F. 
     As shown in  FIG. 6B , when the leading end  38  of the male lead post assembly  26  is received within the receiving groove  40  of the female lead post assembly  28 , the extending member  66  may extend into the cavity  58  of the central post  56  of the male lead post assembly  26 . The slot  80  of the locking member  72  may be positioned above the recessed portion  70  of the extending member  66  and a longitudinal cavity  92  of the locking member  72  may extend over the enlarged end portion  68  of the extending member  66 . 
     As shown in  FIG. 6C , when the closure assembly  24  reaches a predetermined temperature, for example, about 500 degrees F., the locking member  72  may move toward the opening  60 . For example, when heated to the predetermined temperature, the fusible material  90  of the fusible link  84  may melt and the first member  86  and the second member  88  of the fusible link may become separated and the fusible link  84  may no longer support the locking member  72 . A biasing force may then cause the locking member  72  to be moved toward the opening  60 . For example, the biasing force may be solely a gravitational force acting on the locking member  72 . Although other biasing forces may be used, gravitation force may provide a simple, reliable means to bias the locking member  72  and, unlike other biasing means such as springs and elastic material, may not be damaged by heat from a fire. 
     As the locking member  72  falls toward the opening  60 , and the extending member  66  positioned therethrough, the tapered portion  78  and the slot  80  of the locking member  72  may interact with the recessed portion  70  of the extending member  66 . For example, if the slot  80  of the locking member  72  is not completely aligned with the recessed portion  70  of the extending member  66 , the tapered portion  78  may contact the recessed portion  70  of the extending member  66  and may cause the slot  80  of the locking member  72  to become aligned with the recessed portion  70  of the extending member  66  as the locking member  72  falls from a first position above the opening  60  into a second, locked position. The slot  80  of the locking member  72  may extend over the recessed portion  70  of the extending member  66  and a top portion of the slot  80  may contact a top portion of the recessed portion  70  of the extending member  66  and cause the locking member  72  to stop, and may hold the locking member  72  in the locked position, as shown in  FIG. 6C . In the locked position, a portion of the locking member  72  surrounding the slot  80  may obstruct the opening  60  to the longitudinal cavity  58  in the central post  56  of the male lead post assembly  26 . This obstruction of the opening  60  may prevent the enlarged end portion  68  of the extending member  66  from passing through the opening  60  and may prevent the extending member  66  from being removed from the longitudinal cavity  58  of the male lead post assembly  26  and may hold the male lead post assembly  26  and the female lead post assembly  28  together. By providing this mechanical lock, the closure assembly may prevent the separation of the lead post assemblies  26  and  28  and maintain an appropriate fire barrier, even under the heat of a fire that may otherwise warp and separate the closure assembly of a conventional fire door. 
     In view of the foregoing, a closure assembly may be provided that improves the reliability, safety and visual aesthetics of a fire door. A closure assembly may be provided that includes a single moving part (relative to a lead post), which may be biased solely by gravity, and which may be reliably activated. Additionally, all of the moving parts (relative to a lead post) are completely enclosed within the closure assembly, which may prevent tampering or inadvertent damage of the locking mechanism. The extending member may be positioned within a recess of a receiving channel, which may prevent damage of the extending member and may prevent people or objects from becoming caught on the extending member. Furthermore, the opening may be sized relatively small, which may improve the aesthetics of the fire door and may prevent tampering or inadvertent damage of the closure assembly. 
     Whereas the invention is illustrated and described herein with reference to specific embodiments thereof, it is to be understood that various changes may be made in adapting the invention to different embodiments without departing from the broader inventive concepts disclosed herein and comprehended by the claims that follow. For example, a closure assembly for a fire door may include multiple locking features, rather than a single locking feature as described. Additionally, the closure assemblies described may be used with any of a number of fire door configurations. 
     Although this invention has been described with reference to particular embodiments, the invention is not limited to these described embodiments. Rather, the invention is limited only by the appended claims, which include within their scope all equivalent devices, systems and methods.