Abstract:
An exit bar employs a dual action latch retractor comprising a slotted link which connects manual and electrically actuated latch retraction means. The slot permits the latch to be retracted by a solenoid latch retractor regardless of the position of the push bar or other manual latch retraction means. A buffer spring transmits energy from the solenoid latch retractor to the push pad so that under normal circumstances actuation of the solenoid latch retractor retracts both the latch and push pad. However, if the push pad is jammed in the projected position, the buffer spring is compressed to permit relative movement between the solenoid latch retractor and the manual latch retraction mechanism. As soon as the force holding the push pad in an extended position is removed, the energy stored in the buffer spring is applied to the push pad through the mechanical linkage to retract the push pad.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to the field of door security systems. More specifically, this invention relates to the use of a push or exit bar for securing a doorway. 
     2. Description of the Related Art 
     Exit bars, also known as push bars or panic bars, that allow egress through a doorway while limiting ingress are well-known components of door security and emergency systems. The conventional exit bar is mounted on the interior side of the door to be secured and is oriented generally horizontally across the face of the door. A housing or frame supports a push pad or bar for receiving a push force. The push force applied to the movable push pad operates a door latch through a linkage to permit opening of the door. Conventional exit bars typically employ a mechanical linkage between the movable push pad and the latch to actuate the latch mechanism for unlatching the door. 
     To avoid excessive wear to the exit bar components during periods of high traffic through a doorway, it is known to fix or “dog” the exit bar in an unlocked condition. Typically, the push pad is locked in its depressed or actuated position to avoid unnecessary wear to the associated linkage. It is also known to equip an exit bar with an electromagnetic latch retractor as described in U.S. Pat. No. 6,104,594, assigned to the assignee of the present invention. By integrating a building security system with exit bars including electromagnetic latch retractors, it is possible to effectuate the latching and unlatching of exit bars remotely and/or automatically. 
     U.S. Pat. No. 6,104,594 describes the use of an electric circuit to generate a high energy pulse through the electromagnet to generate a retraction force sufficient to retract the push pad and with it the mechanical linkage and latch to unlock the door. A possible deficiency of this approach is that, if the push pad is held or jammed in an extended position, the latch cannot be retracted by the electromagnet (even at high power). An alternative arrangement is to apply the electromagnetic retraction force only to the latch, without also retracting the push pad as described in U.S. patent application Ser. No. 09/414,202, filed Oct. 7, 1999 and also assigned to the assignee of the present invention. This permits latch retraction regardless of the position of the push pad. However, in high traffic situations, the push pad and its associated linkages are free to move as people push to open the door and are exposed to the resulting high rates of wear. 
     There is a need in the art for an exit bar equipped with remotely actuateable means for retracting the latch as well as the push pad which will reliably retract the latch even if the push pad is jammed in an extended position. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a new and improved dual action latch retractor for retracting the push pad and latch of an exit bar that will reliably retract the latch regardless of the position of the push pad. 
     Another object of the present invention is to provide a new and improved dual action latch retractor for remotely retracting the push pad and latch of an exit bar. 
     These and other objects are achieved in an exit bar in which a slotted link is used to connect a solenoid latch retractor to the push pad and the associated manual latch retraction mechanism. The slot permits the latch to be retracted by the solenoid latch retractor regardless of the position of the push bar. A buffer spring transmits energy from the solenoid latch retractor to the push pad so that under normal circumstances actuation of the solenoid latch retractor retracts both the latch and push pad. However, if the push pad is jammed in the projected position, the buffer spring is compressed to permit relative movement between the solenoid latch retractor and the manual latch retraction mechanism. Compression of the buffer spring permits the latch to be retracted while the push pad remains in the extended position. As soon as the force holding the push pad in an extended position is removed, the energy stored in the buffer spring is applied to the push pad through the mechanical linkage to retract the push pad. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and advantages of the invention will be evident to one of ordinary skill in the art from the following detailed description, made with reference to the accompanying drawings, in which: 
     FIG. 1 is a schematic view of an exit bar equipped with a dual action latch retractor in accordance with the present invention mounted to a door and illustrating various auxiliary features thereof; 
     FIG. 1A is a partial enlarged front view of the exit bar of FIG. 1, with the push pad removed; 
     FIG. 2 is a sectional view through the exit bar of FIG. 1A, taken along line  2 — 2  thereof and including the push pad; 
     FIG. 3 is the sectional view of FIG. 2 with the solenoid energized and the push pad in an extended position; 
     FIG. 4 is the sectional view of FIG. 2 with the solenoid energized and the push pad in a retracted position; 
     FIG. 5 is a perspective exterior view of the exit bar of FIG. 1A with portions of the push pad and housing removed; and 
     FIG. 6 is a perspective view of the latch mechanism, mechanical linkage and solenoid latch retractor of the exit bar shown in FIGS. 1A through 5 with the push pad, latch mechanism cover and housing removed. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to the drawings, wherein like numerals represent like components or structures throughout the several Figures, a preferred embodiment of an exit bar equipped with a dual action latch retractor in accordance with the present invention is generally designated by the numeral  10 . The exit bar  10  is mounted in a horizontal position across the interior side of a door  12  to be secured (FIG.  1 ). The exit bar  10  latches against a strike  14  mounted to the door frame from which the door  12  is supported. A push force applied at the front of the exit bar  10  retracts the latch bolt  42  from the strike  14  and releases the door  12  to open for egress. Power is supplied to the exit bar  10  from a remote power source  22  over lines  24  in a conventional manner. 
     Exit bars in accordance with the present invention are readily adaptable for communication with a remote control or security system  26 . The remote security system  26  can be used to issue commands to the exit bar  10  to remotely unlatch the door and also to maintain the door in an unlatched state. 
     With reference to FIGS. 1A through 6, the exit bar  10  has an elongated main housing  32  which mounts to the door face to support and surround the exit bar internal components. The length of the housing  32  is preferably sufficiently long to substantially span the width of the door  12 . The main housing  32  is mounted to the door by means of screws or other fasteners (not shown) which secure the back panel  34  of the housing  32  in surface to surface disposition to the interior (secured) face of the door  12 . The main housing  32  is preferably a channel shaped extrusion defining an elongated opening spaced away from the face of the door  12 . A transversely displaceable push pad  36  defines a push face for receiving a push force exerted toward the door  12  by a person attempting egress through the door. The push pad  36  preferably spans a substantial longitudinal portion of the housing  32  adjacent that end of the housing closest the latch assembly  18 . 
     Fixed inside the main housing  32  is a frame  40 . The generally channel shaped frame  40  is secured to the back panel  34  of the main housing  32  by screws or other fasteners (not shown). For purposes of describing the invention as viewed in FIGS. 1A through 6, the main housing  32  defines a central longitudinal axis which extends parallel to the back panel  34  and a transverse axis which extends perpendicularly from the back panel  34 . 
     The exit bar secures the door by use of a latch assembly  18  that may encompass a variety of forms. The latch assembly includes a retractable or releasable latch bolt  42  which is pivotally mounted to a latch frame  20 . The latch bolt  42  is biased toward an extended or latched position by a latch pre load spring  23  that acts on a latch link  21 . A latch cover  19  surrounds the latch housing  20  to keep contaminants from the latch assembly  18 . When push pad  36  is pushed into the housing  32  by a person attempting egress, a pair of parallel push pad rails  44  mounted to the push pad  36  are moved toward the rear panel  34  of the exit bar  10 . 
     With reference to FIGS. 2 through 4, the push pad  36  is mounted to longitudinally extending rails  44  which are pivotally linked to the frame  40  by a master main link  50  and a slave main link  52 . The master main link  50  and slave main link  52  are pivotally connected to the rails  44  by pins  54 ,  56  respectively. As best seen in FIG. 6, a master main link pin  58  extends through the master main link  50  and slidably engages in master main link slots  60  defined by the frame  40 . In a similar construction, a slave main link pin  62  extends through the slave main link  52  and slidably engages in slave main link pin slots  64  defined by the frame  40 . 
     As viewed in FIGS. 2 through 4, the master and slave main links  50 ,  52  extend from the rails  44  to almost the bottom of the channel defined by the frame  40 . A second master main link pin  66  extends through the master main link  50  and slidably engages in master main link lower slots  68  (hidden by auxiliary rail  80  in FIGS. 2-4) defined by frame  40 . A second slave main link pin  70  extends through the slave main link  52  and slidably engages in slave main link lower slots  72  defined by frame  40 . The master and slave lower guide slots  68 ,  72  are oriented generally parallel to the back panel  34  of the housing  32  in the longitudinal direction. A main spring guide  76  is engaged by the second slave link pin  70 . A main spring  78  is compressively engaged between the main spring guide  76  and a flange formed by the frame  40  to bias the push pad  36  and associated master and slave main links  50 ,  52  toward a projected position (best seen in FIGS.  2  and  3 ). 
     Opposed auxiliary rails  80  connect the master and slave main links  50 ,  52  at their second master and slave main link pins  66 ,  70 . The construction of the master and slave main links  50 ,  52  and the associated pins and slots define a transverse path of motion, e.g., toward the door, for the push pad  36  and rails  44 . Upon application of a push force, the transverse motion of the rails  44  and push pad  36  toward the door is translated into a generally longitudinal motion away from the latch  42  at second master main link pin  66  and second slave main link pin  70 . The provision of auxiliary rails  80  linking second master and slave main link pins  66 ,  70  ensures that a push force applied to either end of the push bar  36  will result in a substantially equivalent longitudinal motion at the bottom of the master main link  50 . 
     The master and slave main links  50 ,  52 , master and slave link slots  60 ,  64 , lower guide slots  68 ,  72 , rails  44 , push pad  36  and auxiliary rails  80  act in concert to form a manual latch retraction mechanism which translates a push force applied to the push pad into a longitudinal latch retraction force at the second master main link pin  66  located at the bottom of the master main link  50 . As best seen in FIGS. 2-4, the second master main link pin  66  passes through a slot  67  defined by a solenoid link  90 . The solenoid link is operatively connected between a solenoid plunger  94  and latch link  21  for transmitting a retraction force generated by the solenoid  92  to the latch assembly  18 . An adjuster  96  (best seen in FIG. 6) fixes one end of the solenoid link to the solenoid plunger  94 . The adjuster permits fine tuning of the position of the solenoid link relative to the solenoid plunger  94  and solenoid  92 . The adjuster  96  has a shaft that penetrates an axial bore in the solenoid plunger  94 . The shaft is fixed in a selected position relative to the plunger  94  by set screws (not shown) in bores that intersect the axial bore. 
     As best seen in FIGS. 1A,  5  and  6 , the solenoid link defines a yoke comprising two transversely spaced arms which extend longitudinally toward the latch assembly before bending toward each other to define a parallel, closely spaced connection on either side of the latch link  21 . Solenoid link  90  and latch link  21  are connected by a pin  17  which is slidably engaged in longitudinal slots  15  defined by the frame  40  (see FIG.  6 ). 
     A coiled buffer spring  100  surrounds a buffer spring guide  98  disposed between the arms of the solenoid link  90 . Pin  66  passes through one end of the buffer spring guide to fix the guide relative to the lower end of the master main link  50 . The closely spaced arms of the solenoid link  90  define a solenoid link slot  67 . Second master main link pin  66  extends transversely through the outer auxiliary rails  80 , lower guide slots  68  defined by the frame, master main link  50 , solenoid link slot  67  and the buffer spring guide  98 . Thus, the second master main link pin  66  is movable in a longitudinal direction relative to the frame  40  in longitudinal slots  68  and also in solenoid link slot  67  relative to the solenoid link. 
     The function of an exit bar  10  equipped with a dual-action latch retractor in accordance with the present invention will now be described with reference to FIGS. 1A through 6. FIGS. 1A,  2 ,  5  and  6  illustrate the relative positions of the components of the exit bar  10  in a stable, latched condition. Latch  42  is biased toward its extended latched position by latch preload spring  23 , which is compressively engaged between a flange of the frame  40  and connecting pin  17  which joins the arms of the solenoid link  90  to the latch link  21 . Push pad  36  and the associated parts of the manual latch retraction mechanism are biased toward an outwardly projected position by main spring  78 . Main spring  78  is compressively engaged between the main spring guide  76  and a flange projecting from the frame  40 . It should be noted that latch preload spring  23  biases the latch  42  toward its projected latched position and also biases the solenoid link  90  and attached solenoid plunger  94  toward the position illustrated in FIG.  2 . 
     A push force applied to the push pad is coupled by rails  44  to the upper end of the master and slave main links  50 ,  52  through pins  54 ,  56 . The master and slave main links  50 , 52  move inwardly relative to the exit bar housing  32  and frame  40  with master main link pin  58  and slave main link pin  62  guided in master and slave main link pin slots  60 ,  64 . It should be noted that the master and slave main link slots  60 , 64  are angled such that movement of the push pad  36  relative to the exit bar housing  32  and latch cover  19  is substantially perpendicular, e.g., toward the face of the door  12 . The inward and pivoting movement of master and slave main links  50 ,  52  in response to a push force causes master and slave second main link pins  66 ,  70  to move longitudinally away from the latch assembly  18  in slots  68 ,  72 . When the push bar has been fully compressed into the exit bar housing  32  by a push force, second main link pin  66  has reached the end of solenoid link slot  67  and exerted a retraction force on the latch  42  via the latch link  21  (see FIG.  4 ). In this position, the main spring  78  is compressed between the main spring guide and the frame  40 . Buffer spring  100  is not compressed because the relative positions of the solenoid link  90  and the master main link  50  lower end have not changed. In other words, second main link pin  66  is still at the right hand end of solenoid link slot  67 . Release of the push force against the push pad  36  will permit the main spring  78  and latch pre load spring  23  to return the components of the exit bar to their extended latched positions as illustrated in FIG.  2 . 
     An exit bar  10  equipped with a dual-action latch retractor in accordance with the present invention may also be unlocked, e.g., latch  42  retracted, by actuation of solenoid  92 . The exit bar  10  is equipped with control electronics  110  for generating current in solenoid  92  to produce a magnetic field which in turn creates a retraction force on solenoid plunger  94 . Solenoid, link  90  and connected latch link  21  apply the retraction force generated by the solenoid to the latch  42 . The dual-action latch retractor in accordance with the present invention is configured to retract both the latch  42  and the push bar  36  with its associated linkages. Retracting the latch  42  releases the door  12  for egress while retracting the push pad  36  and its associated manual latch retraction mechanism avoids excessive wear on the mechanism during periods of high traffic through the door. 
     Since the latch retraction force generated by the solenoid must also retract the push pad  36  and its associated manual latch-retraction mechanism, the initial force generated by the solenoid  92  must be substantial. Therefore, the control electronics  110  are capable of generating an initial high-current pulse to overcome the inertia of the push pad  36  and its associated manual latch retraction mechanism as well as overcoming the force exerted on the latch by the latch preload spring  23 . Maintaining the components of the exit bar in the positions illustrated in FIG. 4 requires less current than the initial movement thereto, so the control electronics also provide a lower current retaining power to the solenoid  92  following the initial retraction pulse. 
     In accordance with a particular aspect of the present invention, the dual-action latch retractor is provided with means for permitting relative movement between the solenoid link  90  and the lower end of the master main link  50  (second master main link pin  66 ). This allows the retraction force generated by the solenoid  92  to retract the latch  42  regardless of the position of the push pad  36  and its associated manual latch-retraction mechanism. It is advantageous for the door to be capable of remote automated release even when the push pad  36  and/or the manual latch retraction mechanism are jammed in their extended latched positions. Further, it is advantageous that when the jamming force is released, the dual-action latch retractor then retract the push pad  36  and its associated manual latch-retraction mechanism to avoid wear commonly associated with high traffic situations. 
     These objects are achieved in the illustrated preferred embodiment by applying the retraction force generated by the solenoid  92  to the master main link  50  through a buffer spring  100 . When the push bar is free to move and the solenoid is actuated, the buffer spring  100  efficiently transmits the retraction force to the lower end of the master main link  50  to retract the push pad and the manual latch-retraction mechanism. If the push pad is jammed, as illustrated in FIG. 3, the solenoid  92  is still capable of retracting the latch  42  via the solenoid link  90  and the latch link  21 . The buffer spring  100  is compressed by the altered relative positions of the master main link second pin  66  and the solenoid link  90 . As can be seen in FIG. 3, pin  66  has moved to the left end of solenoid link slot  66  thereby compressing the buffer spring  100  which is engaged between the buffer spring guide  98  and the solenoid link  90 . When the jamming force is removed, energy stored in the compressed buffer spring  100  is sufficient to retract the push pad and the associated manual latch-retraction mechanism. 
     Thus, the dual-action latch retractor in accordance with the present invention is capable of retracting both the latch and the manual latch-retraction mechanism of an exit bar regardless of the position of the push pad relative to the exit bar housing  32 . The exit bar  10  is fully integratable with building security and alarm systems, permitting remote automatic release and dogging of the latch and manual latch-retraction mechanisms, respectively. 
     While a preferred embodiment of the foregoing invention has been set forth for purposes of illustration, the foregoing description should not be deemed a limitation of the invention herein. Accordingly, various modifications, adaptations and alternatives may occur to one skilled in the art without departing from the spirit and the scope of the present invention.