Patent Abstract:
A lock cylinder monitoring assembly for monitoring position of a lock cylinder. The monitoring assembly includes a housing having an inner cavity and an exterior diameter. The exterior diameter of the housing is not significantly greater than the corresponding cylinder diameter. The assembly further includes a switch received into the inner cavity of the housing. The switch is in electrical communication with an indicator. The switch is reactive to any change in position of the lock cylinder.

Full Description:
CROSS-REFERENCES 
     This application is related to U.S. provisional application No. 61/148,519, filed Jan. 30, 2009, entitled “Self-Adjusting Cylinder Monitor Assembly”, naming Tracy F. Fowler, Brian R. Fournier and Damon John Lenk as inventors. The contents of the provisional application are incorporated herein by reference in their entirety, and the benefit of the filing date of the provisional application is hereby claimed for all purposes that are legally served by such claim for the benefit of the filing date. 
    
    
     BACKGROUND 
     This invention relates generally to lock monitoring systems, and more particularly to a lock monitoring system for determining the position of a lock cylinder in a mortise lock assembly. 
     There are a number of different ways that users have attempted to make locks “tamper proof” using lock monitoring systems. Some systems incorporate alarms associated with the insertion of an incorrect key into a lock cylinder. The alarms cooperate with the inner workings of the lock cylinder, such as the pin/tumbler assembly, to signal when there is tampering with the pin/tumbler assembly within the cylinder. The alarms provide an audio or visual indication, or trigger a locking mechanism, when the pins within the lock cylinder are improperly manipulated. 
     Other conventional lock monitoring systems signal an alarm when the lock assembly is being pried or jimmied or otherwise forcibly engaged. The lock assembly includes sensors and, when there is an attempt to pry or damage the lock assembly or surrounding frame, the sensors signal an alarm. 
     Lock monitoring systems do not typically address the position of the lock cylinder. In a mortise lock assembly, the lock cylinder rotates a cam to place the lock in a locked condition or an unlocked condition, as well as to retract a latch or a deadbolt to a retracted position. Therefore, the rotation of the lock cylinder and cam is usually an indication of either ingress or egress through the door. 
     Mortise lock assemblies vary in size and depth. Similarly, lock cylinders also vary in size and depth, as does the shape and design of the cam. Thus, it is difficult to provide a lock monitoring system for a lock cylinder that will work effectively with all mortise lock assemblies and lock cylinders. 
     For the foregoing reasons, there is a need for a lock monitoring system that monitors the position of the lock cylinder. The new lock monitoring system should signal an alarm, or be integrated into an alarm system where rotation of the lock cylinder may be monitored for security reasons. Ideally, the new lock monitoring system should be applicable to new and existing mortise lock assemblies, especially in a retrofit application. 
     SUMMARY 
     The present invention provides for a lock cylinder monitor for monitoring the position of a lock cylinder. The lock cylinder monitor has a housing having an inner cavity and an exterior diameter, the exterior diameter being no greater than the corresponding lock cylinder diameter. The lock cylinder monitor also includes a switch received into the inner cavity of the housing. The switch is in electrical communication with an indicator. The lock cylinder monitor also includes a spring for urging the switch outwardly of the inner cavity of the housing, and a retainer for holding the spring adjacent to the switch. 
     The present invention further provides for a lock cylinder assembly having a lock cylinder, and a lock cylinder monitor for monitoring the position of the lock cylinder. The lock cylinder monitor includes a housing having an inner cavity and an exterior diameter, the exterior diameter being no greater than the corresponding lock cylinder diameter, a switch received into the inner cavity of the housing, the switch in electrical communication with an indicator, a spring for urging the switch into the inner cavity of the housing, and a retainer for urging the spring to remain adjacent to the switch. 
     Another aspect of the present invention provides for a mortise lock assembly having a mortise lock body, a lock cylinder, and a lock cylinder monitor assembly for monitoring the position of the lock cylinder. The lock cylinder monitor assembly has a housing having an inner cavity and an exterior diameter, the exterior diameter being no greater than the corresponding lock cylinder diameter. The lock cylinder monitor assembly further includes a switch received into the inner cavity of the housing, the switch in electrical communication with an indicator. The lock cylinder monitor assembly also includes a spring for urging the switch into the inner cavity of the housing, and a retainer for urging the spring to remain adjacent to the switch. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is an exploded perspective view of a mortise lock assembly. 
         FIG. 1B  is a perspective view of an embodiment of a lock cylinder monitoring assembly as shown in  FIG. 1A . 
         FIGS. 2A and 2B  are exploded perspective views from opposite sides of the lock cylinder monitoring assembly and the lock cylinder as shown in  FIG. 1A . 
         FIG. 3  is a front elevation view of the lock cylinder monitoring assembly as shown in  FIG. 1B . 
         FIG. 4  is a cross-section view of the lock cylinder monitoring assembly taken along line  4 - 4  of  FIG. 3 . 
         FIG. 5  is cross-section view of the lock cylinder monitoring assembly taken along line  5 - 5  of  FIG. 3 . 
         FIG. 6A  is a side elevation view of the lock cylinder monitoring assembly and the lock cylinder as shown in  FIG. 1A  in a first position relative to a mortise lock housing shown in cross-section. 
         FIG. 6B  is a side elevation view of the lock cylinder monitoring assembly and the lock cylinder as shown in  FIG. 6A  in a second position relative to a mortise lock housing shown in cross-section. 
         FIG. 7A  is an elevation view of a cam of a lock cylinder and a portion of a lock cylinder monitoring assembly in a first relative position. 
         FIG. 7B  is an elevation view of the cam and the portion of the lock cylinder monitoring assembly as shown in  FIG. 7A  in a second relative position. 
         FIGS. 8A and 8B  are a perspective view and an exploded perspective view, respectively, of another embodiment of a lock cylinder monitoring assembly. 
         FIGS. 9A and 9B  are a perspective view and an exploded perspective view, respectively, of the lock cylinder monitoring assembly shown in  FIGS. 8A and 8B  from the opposite side as shown in  FIGS. 8A and 8B . 
         FIG. 10  is a front elevation view of the lock cylinder monitoring assembly as shown in  FIGS. 8A-9B . 
         FIG. 11  is a cross-section view of the lock cylinder monitoring assembly taken along line  11 - 11  of  FIG. 10 . 
         FIG. 12  is cross-section view of the lock cylinder monitoring assembly taken along line  12 - 12  of  FIG. 10 . 
         FIG. 13A  is a side elevation view of the lock cylinder monitoring assembly as shown in  FIGS. 8A-9B  and a lock cylinder in a first position relative to a mortise lock housing. 
         FIG. 13B  is a side elevation view of the lock cylinder monitoring assembly and the lock cylinder as shown in  FIG. 13A  in a second position relative to a mortise lock housing. 
     
    
    
     DESCRIPTION 
     The embodiments of a lock cylinder monitoring assembly described herein is for use in a mortise lock and may be used with any conventional mortise lock such as, for example, the mortise locks described by U.S. Pat. No. 6,393,878 and U.S. Pat. No. 6,349,982, the contents of which are hereby incorporated by reference. Accordingly, detailed explanations of the functioning of all of the components of the mortise lock are deemed unnecessary for understanding of the present invention by one of ordinary skill in the art. 
     Certain terminology is used herein for convenience only and is not to be taken as a limitation on the invention. For example, words such as “interior”, “exterior”, “upper,” “lower,” “left,” “right,” “horizontal,” “vertical,” “upward,” and “downward” merely describe the configuration shown in the FIGs. Indeed, the components may be oriented in any direction and the terminology, therefore, should be understood as encompassing such variations unless specified otherwise. 
     Referring now to the drawings, wherein like reference numerals designate corresponding or similar elements throughout the several views,  FIG. 1A  shows an embodiment of a mortise lock assembly generally designated at  10 . The mortise lock assembly  10  is conventional and only a few of the mortise lock components are shown, including a lock case  12  and a key-operated lock cylinder  14 . Also shown in  FIG. 1A  is an embodiment of a lock cylinder monitoring assembly, generally designated at  16 . 
     As is known in the art, the mortise lock case  12  is adapted to fit into a mortised recess formed in the edge of a door (not shown) which is opposite to the edge of the door that is hinged to a door frame. The lock case  12  is generally rectangular and encloses the lock components. The principal lock components are a beveled latch bolt  18 , a deadbolt  20  and an auxiliary bolt  22 . Both of the latch bolt  18  and the deadbolt  20  may project from the case  12  beyond the edge of the door and into openings in the door frame to latch or lock the door in a closed position. The latch bolt  18  and the deadbolt  20  are moveable to a retracted position inside the case  12  to permit opening of the door by operation of a latch operator (not shown), such as a door knob or lever handle. 
     The lock cylinder  14  has an elongated threaded body  24 . The cylinder body  24  accommodates a rotatable key plug  26 , the inner end of which carries an eccentric cam  28 . Rotation of the key plug  26  by a key in the cylinder body  24  causes corresponding rotation of the cam  28 . The major side walls of the lock case  12  define opposed circular openings  30  in the upper rear corners for threadably receiving the lock cylinder  14 . During installation of the mortise lock  10 , a transverse opening is drilled in a face of the door and opens into the recess in the edge of the door. The transverse opening is positioned to align with the openings in the lock case  12  when the lock case  12  is in the recess. The lock cylinder  14  is inserted into the transverse opening and threaded into the opening  30  on one side of the lock case  12 . The lock cylinder  14  is advanced into the lock case  12  until an outer trim flange  32  is flush against the door surface. The distance the cylinder body  24  advances into the lock case  12  will vary based on the thickness of the door. 
     As is known in the art, the cam  28  is adapted to operatively engage lock components to effect a locked condition and an unlocked condition of the mortise lock  10 . Optionally, the cam  28  may function to selectively extend and retract the deadbolt  20  or retract the latch bolt  18 . All of the operations of the cam  28  require rotation of a key in the lock cylinder  14  for rotating the key plug  26  and the cam  28 . 
     Referring to  FIGS. 1B ,  2 A and  2 B, the lock cylinder monitoring assembly  16  comprises a housing  34 , a plunger  36  and a coil spring  38 . The monitor housing  34  is a generally circular member, including an inner portion  40  of some depth and a generally planar outer flange portion  42 . The outer flange portion  42  has a larger diameter than the inner portion  40  of the housing. The periphery of the inner portion  40  of the housing includes four flexible tabs  44  depending inwardly from the flange portion  42 . 
     The plunger  36  is a generally rectangular member, including an inner portion  46  of some depth and a generally planar outer flange portion  48  of slightly larger dimensions than the inner portion  46  of the plunger  36 . The inner portion  46  of the plunger  36  has an axial boss  50  extending partially along the inner surface. The plunger  36  defines an oblong recess  52  for receiving a switch  54 . The switch  54  is fixed within the recess  52  using any number of suitable adhering means such as the application of an adhesive such as glue. Other methods of fixing the switch  54  within the plunger recess  52  are contemplated. They include but are not limited to mechanical means such as screws and pins, as well as other chemical means such as epoxy resin, as well as heat so as to melt the switch  54  within the recess  52 . In an assembled position, the switch  54  is completely embedded within the switch recess  52  in the plunger  36 . 
     The monitor housing  34  defines a pass through opening  56  which is sized and shaped to slidably receive the plunger  36 . A pair of opposed arcuate walls  58  further define the opening  56  at the midpoint and partially form a spring recess. A pair of opposed axial tabs  60  extend inwardly from the outer flange portion  48  of the plunger  36  and into the arcuate portions  58  of the opening  56 . The inner end of the opening  56  is defined by end walls  62  that integral with the inner portion  46  of the plunger  36  and extend transversely for partially closing the opening  56 . 
     To assemble the lock cylinder monitoring assembly  16 , the plunger  36  and switch  54  are slipped into the opening  56  in the housing  34 . The plunger  36  slides freely within the housing  34 . Inward axial movement of the plunger  36  is limited by engagement of the outer flange portion  48  of the plunger  36  with the end walls  62  at the inner end of the opening  56 . The spring  38  is then placed within the opening  56  in the spring recess partially defined by the arcuate inner walls  58  of the housing  34 . The outer surface of the plunger  36  defines a partial circular recess  64  for receiving the inner end of the spring  38 . The spring  38  is held in compression by positioning the outer coil under the tabs  60 . The spring  38  thus serves to hold the plunger  36  within the housing  34  while biasing the plunger  36  against the end walls  62 , as best seen in  FIGS. 4 and 5 . It is understood that other means for inwardly biasing the plunger  36  are possible. Thus, we do not intend to limit ourselves to the specific embodiments of the spring biasing means shown herein. 
     The inner portion  40  of the monitor housing  34  is sized to be received in the cylinder opening  30  in the case  12  opposite the lock cylinder  14 . Referring to  FIGS. 6A and 6B , the inner portion  40  of the housing  34  is press fit into the opening  30  in the case  12 . As the housing  34  advances into the case  12 , the flexible tabs  44  on the flange portion of the housing  34  engage the case  12  adjacent the opening  30  and flex inwardly. As the housing  34  advances into the case  12 , the tabs  44  clear the wall of the case  12  and snap outwardly. Ridges on the tabs  44  thus engage the inner surface of the wall of the case  12  for holding the lock cylinder monitoring assembly  16  in the lock case  12 . 
     As described above, during installation of the mortise lock  10 , the lock cylinder  14  is inserted through an opening in the door face and threaded into the opening  30  in the lock case  12 . As the lock cylinder  14  is threaded into the case  12 , the boss  50  on the plunger  36  initially engages the cam  28  of the lock cylinder  14 . As the lock cylinder  14  advances, the plunger  36  is pushed into the housing  34  against the force of the spring  38  until the trim flange  32  on the lock cylinder  14  is flush against the door surface. Thus, the lock cylinder monitoring assembly  16  is able to accommodate varying depths of lock cylinder  14  intrusion into the case  12  due to lock cylinder bodies  24  of varying lengths and varying door thicknesses. 
     In an assembled position, the lock cylinder  14  and the lock cylinder monitoring assembly  16  make frictional contact at the cam  28  and the boss  50 . A magnet  29  is embedded flush with the surface of the cam  28  so that the cam  28  is free to rotate within the lock case  12 . In one embodiment, the switch  54  is a Reed switch, which operates by an applied magnetic field. The switch  54  has at least one pair of electrical contacts (not shown) therein. The contacts remain either normally open or normally closed when a magnetic field is applied. In one embodiment, the contacts within the switch  54  are normally closed when a magnetic field is applied. Thus, if the magnet  25  were to move upon rotation of the cam  24 , the switch  54  would open at the absence of a magnetic field for generating an electric signal indicating that the cam  28  has moved. As seen in the FIGs., electrical wiring  66  is provided for electrically connecting the switch  54 . A radial notch  68  in the flange portion  42  of the housing  34  is sized and dimensioned to pass the wire  66 . 
       FIG. 7A  shows the cam  28  in an initial home position where switch  54  is aligned with the magnet  29  embedded in the cam  28 . When a key is inserted in the key plug  26 , the key, key plug  26  and cam  28  can rotate together for effecting a lock function.  FIG. 7B  shows the position of the cam  28  after rotation from the home position. When the cam  28  rotates, the magnet  29  moves away from the switch  54 . Because the switch  54  is able to indicate presence or loss of magnetic field, if the switch  54  is normally closed the switch  54  opens and thus disrupts the normal flow of current in the circuit. This sends an electrical signal over the wire  66  generally indicating that the cam  28  has moved from its home position. 
     The wire  66  from the switch  54  may be connected to a remote alarm or other indicator (not shown). The indicator may be an audio or visual signal, or may be connected to an alarm/security system where the signal from the indicator may be recorded as an event for security auditing, shunt an alarm when lock cylinder use is acceptable (i.e., lock cylinder used to open door instead of electronic credential (keycard, pin code)), or notify security or initiate an alarm at a time when lock cylinder use is not acceptable. Uses of the signal from the switch  54  may be expanded to accommodate specific security requirements as well as alarm system monitoring capabilities. 
     Referring now to  FIGS. 8A-9B , another embodiment of a cylinder lock monitoring assembly is shown and generally designated at  70 . The lock cylinder monitoring assembly  70  comprises a housing  72 , a plunger  74  and a coil spring  76 . As in the previous embodiment, the monitor housing  72  is a generally circular member, including an inner portion  78  and an outer flange portion  80  of a larger diameter and including four inwardly depending flexible tabs  82 . In this embodiment, the outer flange portion  80  further comprises a planar extension  92  which projects upwardly and terminates in a perpendicular flange  94  that extends inwardly from the extension  92 . 
     The plunger  74  is a generally X-shaped member. The plunger  74  defines a central circular blind bore  84  for receiving the spring  76 . A switch sensitive to a magnetic field is integral with the plunger  74 . The monitor housing  72  defines an X-shaped pass through opening  86  which is sized and shaped to slidably receive the plunger  74 . A pair of opposed axial tabs  88  extend inwardly from the outer flange portion  80  into the opening  86 . The housing  72  also has a pair of opposed axial tabs  90  at the inner end of the opening  86  that extend transversely from the inner portion  78  into the opening  86 . 
     To assemble the lock cylinder monitoring assembly  70 , the plunger  74  is slipped into the opening  86  in the housing  72  and slides freely within the housing  72 . Inward axial movement of the plunger  74  is limited by engagement of the tabs  90  on walls  96  connecting the legs of the plunger  74 . The spring  76  is then placed within the opening  84  and positioning the outer coil under the axial tabs  88 . As in the previous embodiment, the spring  76  thus serves to hold the plunger  74  within the housing  72  while biasing the plunger  74  inwardly against the tabs  90 , as best seen in  FIGS. 11 and 12 . 
     The inner portion  78  of the monitor housing  72  is received in the cylinder opening  30  in the lock case  12  in the same manner as the previous embodiment. Referring to  FIGS. 13A and 13B , in this embodiment the extension  92  lies against the wall of the case and the flange  94  fits into a slot  98  in the top wall of the case  12 . In use, this embodiment of the lock cylinder monitoring assembly  70  functions the same way as the previous embodiment. As the lock cylinder  14  is threaded into the opening  30  in the lock case  12 , the plunger  74  initially engages the cam  28  and is pushed into the housing  72  against the force of the spring  76  until the trim flange  32  on the lock cylinder  14  is flush against the door surface. In use, the switch integral with the plunger  74  senses the magnet  29  in the cam  28 . Accordingly, the switch generates an electric signal indicating that the cam  28  has moved, which signal is communicated via the electrical wiring  66 . 
     It is understood that the embodiments of the lock cylinder monitoring assembly described herein may be retrofit to existing single cylinder mortise lock designs. The mortise lock assembly would be installed as a standard mortise lock assembly, except that the wiring from the switch to the indicator would need to be provided. 
     Although the present invention has been shown and described in considerable detail with respect to only a few exemplary embodiments thereof, it should be understood by those skilled in the art that we do not intend to limit the invention to the embodiments since various modifications, omissions and additions may be made to the disclosed embodiments without materially departing from the novel teachings and advantages of the invention, particularly in light of the foregoing teachings. Accordingly, we intend to cover all such modifications, omission, additions and equivalents as may be included within the spirit and scope of the invention as defined by the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures.

Technology Classification (CPC): 4