Patent Publication Number: US-2023146139-A1

Title: Low-voltage access control device

Description:
TECHNICAL FIELD 
     The invention set forth in the appended claims relates generally to systems and apparatuses for controlling access to a building, including, without limitation, electromechanical push bar exit devices. 
     BACKGROUND 
     Push bar exit devices, also known as crash bars or panic bars, are in widespread use in commercial buildings and allow occupants to quickly open a latched door by pressing a bar on the door. While such devices may be beneficial for emergency use, they are also generally more convenient than other types of exit devices. 
     While the benefits of push bar exit devices are widely known, improvements to such devices can significantly reduce cost of operation, including power and maintenance requirements. 
     BRIEF SUMMARY 
     New and useful systems and apparatuses for controlling access to a building are set forth in the appended claims. Illustrative embodiments are also provided to enable a person skilled in the art to make and use the claimed subject matter. 
     For example, some embodiments may comprise a low-voltage, direct current apparatus for controlling a door. The apparatus may comprise a mounting bar configured to be coupled to the door; a latch coupled to the mounting bar, the latch comprising a locking lever; and an actuator configured to move the locking lever between a locked position in which the locking lever prevents movement of the latch to an unlocked position in which the locking lever allows movement of the latch. 
     In more particular embodiments, the actuator may comprise a lead screw, a nut, and a motor. The nut may be threaded onto the lead screw and configured to engage the locking lever. The motor may be configured to rotate the lead screw in a first direction to push the nut against the locking lever, thereby moving the locking lever from the locked position to the unlocked position. The motor may also be configured to rotate the lead screw in a second direction to retract the nut from the locking lever. A spring may be configured to return the locking lever to the locked position if the motor retracts the nut from the locking lever. In yet more particular embodiments, the motor may be operable by direct current at less than twelve volts, and more preferably, less than nine volts. 
     In some embodiments, the latch may comprise a starwheel coupled to the mounting bar, and the actuator may be configured to move the locking lever between the locked position in which the locking lever prevents rotation of the starwheel to the unlocked position in which the locking lever allows rotation of the starwheel. 
     Additionally, or alternatively, some embodiments may comprise a system for controlling access to a door. For example, a system may comprise a strike configured to be coupled to a frame around the door; a mounting bar coupled to the door; and a latch coupled to the mounting bar and configured to engage the strike. The latch comprising a locking lever, and an actuator may be configured to move the locking lever between a locked position in which the locking lever prevents release of the latch from the strike to an unlocked position in which the locking lever allows release of the latch from the strike. An access control unit configured to operate the actuator. The access control unit may be operated by a source of direct current at less than twelve volts, and preferable less than nine volts. The source of direct current may be a battery, for example, which can also provide direct current to the actuator. 
     Features, elements, and aspects described in the context of some embodiments may also be omitted, combined, or replaced by alternative features. Other features, objectives, advantages, and a preferred mode of making and using the claimed subject matter are described in greater detail below with reference to the accompanying drawings of illustrative embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings illustrate some objectives, advantages, and a preferred mode of making and using some embodiments of the claimed subject matter. Like reference numbers represent like parts in the examples. 
         FIG.  1    is a schematic diagram of an example of a system for controlling access to a building. 
         FIG.  2    is another schematic diagram of the system of  FIG.  1   . 
         FIG.  3    is a top view of an example of an exit device that may be associated with the system of  FIG.  1   . 
         FIG.  4    is schematic diagram of an example of a latch that may be associated with the device of  FIG.  3   . 
         FIG.  5    is an auxiliary view of the exit device of  FIG.  3   . 
         FIG.  6    is a schematic diagram of an example of an actuator that may be associated with the device of  FIG.  5   . 
     
    
    
     DESCRIPTION OF EXAMPLE EMBODIMENTS 
     The following description of example embodiments provides information that enables a person skilled in the art to make and use the subject matter set forth in the appended claims, but it may omit certain details already well known in the art. The following detailed description is, therefore, to be taken as illustrative and not limiting. 
       FIG.  1    is a schematic diagram of an example of a door system  100 . In the example of  FIG.  1   , the door system  100  comprises a door frame  105  and a door  110  configured to open to the exterior of a structure. The door system  100  may additionally comprise an exit device  115 , a strike  120 , and a transfer loop  125 . For example, the exit device  115  may be coupled to the door  110 , and the strike  120  may be coupled to the door frame  105 . The transfer loop  125  may comprise or consist essentially of an electrical conductor between the door frame  105  and the door  110 . 
       FIG.  2    is another schematic diagram of the door system  100  of  FIG.  1   , illustrating additional details from the opposite side that may be associated with some embodiments. For example, the door system  100  of  FIG.  2    may have an access control unit  205  and a conductor  210 . In some embodiments, the access control unit  205  may be configured to read or receive a signal from an identification unit (not shown), such as a radio frequency identifier (RFID), a magnetic stripe card, keypad, biometric scanner, or Bluetooth device. The access control unit  205  may be powered by relatively low-voltage, direct current source, such as a battery having a voltage in a range of about three (3) volts to about nine (9) volts. The conductor  210  may electrically couple the access control unit  205  to the exit device  115  (shown in  FIG.  1   ). 
       FIG.  3    is a top view of an example of the exit device  115  of  FIG.  1   , illustrating additional details that may be associated with some embodiments. In the example of  FIG.  3   , the exit device  115  generally comprises an activation bar  305 , an end cap  310 , a front cap  315 , and a latch  320 , which may be configured to engage the strike  120 . The latch  320  of  FIG.  3    comprises a nose guard  325  and a starwheel  330 , which can engage the strike  120 . In other embodiments, the latch  320  may comprise or consist of other types of fasteners, such as a slam latch or bolt. 
       FIG.  4    is schematic diagram of an example of the latch  320  of  FIG.  3   , illustrating additional details that may be associated with some embodiment. As shown in the example of  FIG.  4   , the latch  320  may comprise a locking lever  405 , which can be configured to slide within the latch  320 . For example, a retention bar  410  can be coupled to the nose guard  325  or another support structure, such as a mounting bar  415 , and the locking lever  405  can slide through the retention bar  410 . The retention bar  410  can constrain movement of the locking lever  405  in other directions. The latch  320  may additionally comprise a spring  420 , which may have a first end coupled to the retention bar  410  and a second end coupled to the locking lever  405 . 
     In the example of  FIG.  4   , the starwheel  330  mounted or otherwise coupled to the mounting bar  415 , and the locking lever  405  is in a locked position in which a first end of the locking lever  405  engages the starwheel  330  to prevent rotation of the starwheel  330 . If the starwheel  330  is coupled to the strike  120  (shown in  FIG.  1   ), this configuration can prevent the door  110  from opening. In operation, a force can be applied to a second end of the locking lever  405  to move the locking lever  405  to an unlocked position in which the first end of the locking lever  405  is disengaged from the starwheel  330 . In the unlocked position, the starwheel  330  can be rotated, allowing the starwheel  330  to be released from the strike  120 . In this configuration, the door  110  may be opened. If the force is removed from the second end of the locking lever  405 , the spring  420  can apply a force to the locking lever  405  that causes the locking lever  405  to return to the locked position. 
       FIG.  5    is an auxiliary view of the exit device  115  of  FIG.  3   , illustrating additional details that may be associated with some embodiments. In the example of  FIG.  5   , the activation bar  305  has been removed for illustration purposes. As shown, some embodiments of the exit device  115  may additionally comprise a pivot pin  505  coupled to the mounting bar  415 , a pivot plate  510  coupled to the pivot pin  505 , and a pivot arm  515  that couples the pivot plate  510  to the locking lever  405 . In the example of  FIG.  5   , the pivot arm  515  has a sliding joint  518  configured to interface with the second end of the locking lever  405 . The locking lever  405  of  FIG.  5    is illustrated in a locked position, substantially similar to the locked position illustrated in the example of  FIG.  4   . 
     In operation, a force can be applied to the pivot plate  510 , thereby causing the pivot plate  510  to rotate about the pivot pin  505 . For example, with the activation bar  305  in place, the activation bar  305  may be pressed to apply a force to the pivot plate  510 . Rotation of the pivot plate  510  can cause the pivot arm  515  to move away from the starwheel  330 , thereby applying a force to the locking lever  405  and moving the locking lever  405  to the unlocked position, substantially as described with reference to the example of  FIG.  4   . In the example of  FIG.  5   , sliding joint  518  of the pivot arm  515  applies a pulling force on the locking lever  405 . In the unlocked position, the starwheel  330  can be rotated, allowing the starwheel  330  to be released from the strike  120  ( FIG.  1   ). In this configuration, the door  110  ( FIG.  1   ) may be opened. If the force is removed from the pivot plate  510 , and thereby removed from the locking lever  405 , the spring  420  can apply a force to the locking lever  405  that causes the locking lever  405  to return to the locked position. In some embodiments, a spring may also be coupled to the pivot plate  510 , the pivot arm  515 , or both, to cause the pivot plate  510  to rotate in the opposite direction about the pivot pin  505  to return to the original position. 
     The exit device  115  of  FIG.  5    further comprises an actuator  520 . The actuator  520  of  FIG.  5    generally comprises a motor  525 , a lead screw  530 , and a nut  535 . In some embodiments, the spring  420  may be coupled to the retention bar  410 , which is coupled to the mounting bar  415 . The second end of the spring  420  may be coupled to the locking lever  405 . The motor  525  may be coupled to the mounting bar  415 . For example, the motor  525  may rest or otherwise be mounted on a bar (not visible in  FIG.  5   ), which can be coupled to the mounting bar  415 . In the example of  FIG.  5   , the bar may be disposed over the locking lever  405  to allow the locking lever  405  to slide beneath the bar. A retention clip  540  may be coupled to the bar over the motor  525  to secure the motor  525  in place relative to the mounting bar  415 . A first end of the lead screw  530  may be operatively coupled to the motor  525 , and a second end of the lead screw  530  may be in contact with or otherwise coupled to the locking lever  405 . The motor  525  may be electrically coupled to conductors  545 . 
     In operation, the conductors  545  may be coupled to a low-voltage, direct current source, such as a battery in the access control unit  205  ( FIG.  2   ). The motor  525  can then be operated to control rotation of the lead screw  530 . For example, if the access control unit  205  determines that access should be allowed, the access control unit  205  may deliver power to the motor  525  through the conductors  545 , which can cause the motor  525  to rotate the lead screw  530  in a first direction. The rotation of the lead screw  530  in this first direction can move the nut  535  in a first direction, which can apply a force to the locking lever  405  and move the locking lever  405  to the unlocked position, substantially as described with reference to the example of  FIG.  4   . In the example of  FIG.  5   , the nut  535  applies a push force on the locking lever  405 , which can cause the second end of the locking lever to move within the sliding joint  518  of the pivot arm  515 . In the unlocked position, the starwheel  330  can be rotated, allowing the starwheel  330  to be released from the strike  120 . In this configuration, the door  110  may be opened. If the polarity of the power to the motor  525  is reversed, the motor  525  can rotate the lead screw  530  in a second direction, which can remove the force from the locking lever  405 . For example, the access control unit  205  may be configured to reverse polarity a few seconds after determining access should be allowed. As the force of the nut  535  is removed from the locking lever  405 , the spring  420  can apply a force to the locking lever  405  that causes the locking lever  405  to return to the locked position. 
       FIG.  6    is an assembly diagram of an example of the actuator  520 , illustrating additional details that may be associated with some embodiments. For example,  FIG.  6    illustrates an embodiment of the motor  525  having a shaft  605 , which can be coupled to the lead screw  530 . The nut  535  may be threaded onto the lead screw  530 , and a plate  610  may be coupled to the nut  535  with a screw  615  or other suitable fastener. The plate  610  may be configured to engage a variety of locking levers and may be configured to prevent rotation of the nut  535  relative to the lead screw  530 . 
     In general, components of the door system  100  may be coupled directly or indirectly. For example, the motor  525  may be directly coupled to the lead screw  530  and may be indirectly coupled to the locking lever  405  through the lead screw  530 . Coupling may include fluid, mechanical, thermal, electrical, or chemical coupling (such as a chemical bond), or some combination of coupling in some contexts. For example, motor  525  may be mechanically coupled to the lead screw  530  and may be electrically coupled to the access control unit  205 . In some embodiments, components may also be coupled by virtue of physical proximity, being integral to a single structure, or being formed from the same piece of material. 
     The systems, apparatuses, and methods described herein may provide significant advantages. Some embodiments may be particularly advantageous for reducing the cost of operating and maintaining doorway exit devices. For example, some embodiments can be installed without installing additional power sources or connecting to utility power sources, which can significantly reduce installation cost and allow installation in locations without utility power. 
     While shown in a few illustrative embodiments, a person having ordinary skill in the art will recognize that the systems, and apparatuses described herein are susceptible to various changes and modifications that fall within the scope of the appended claims. Moreover, descriptions of various alternatives using terms such as “or” do not require mutual exclusivity unless clearly required by the context, and the indefinite articles “a” or “an” do not limit the subject to a single instance unless clearly required by the context. Components may also be combined or eliminated in various configurations for purposes of sale, manufacture, assembly, or use. For example, in some configurations, the actuator  520  may be separated from or combined with other components in various ways for sale, manufacture, assembly, or use. 
     The claims may also encompass additional subject matter not specifically recited in detail. For example, certain features, elements, or aspects may be omitted from the claims if not necessary to distinguish the novel and inventive features from what is already known to a person having ordinary skill in the art. Features, elements, and aspects described in the context of some embodiments may also be omitted, combined, or replaced by alternative features serving the same, equivalent, or similar purpose without departing from the scope of the invention defined by the appended claims.