Abstract:
A relocking mechanism that blocks the path of a bolt within a lock assembly is presented. The relocking mechanism comprises a breakaway member that is repositioned when the lock assembly is attacked by some mechanical means, such as impact applied via a hammer and punch to the lock housing through a spindle hole in a door. The breakaway member prior to attack holds a preloaded relocking plunger clear from bolt movement. When the breakaway member is repositioned upon attack, the plunger is free to move under a biasing force into position so as to block the bolt thus keeping the lock in a secure locked state regardless of the state of the locks default blocking mechanism.

Description:
TECHNICAL FIELD 
       [0001]    The application relates generally to locks and, more particularly, to a relocking mechanism for blocking a bolt of a lock from being displaced to its unlocking position in the event of certain types of physical attacks, such as hammering and punching. 
       BACKGROUND OF THE ART 
       [0002]    Locks can be physically attacked in many ways, including hammering, punching and drilling. It is desired that a lock not merely physically resist such attacks, but also respond appropriately to the attacks by ensuring that the bolt of the lock cannot be moved to its unlocking position during or after the attack. 
       SUMMARY 
       [0003]    Therefore, it is an aim of the present application to provide a new relocking mechanism for automatically relocking a lock when the lock is physically attacked. 
         [0004]    In one aspect, there is thus provided a relocking mechanism which is triggered by impact forces transmitted to the lock case assembly, the mechanism comprising a relocking member movable under the impact forces to an operational position in which the lock bolt is physically blocked against movement to an unlocking position thereof. 
         [0005]    In another aspect, there is provided a relocking mechanism for a lock assembly having a bolt movable between a locking position and an unlocking position, the relocking mechanism comprising a breakaway or displaceable member holding a pre-loaded plunger from blocking a bolt until a mechanical attack through a spindle hole in a door to which the lock is mounted causes the breakaway or displaceable member to release the plunger to its functional position in which the plunger blocks the bolt from moving to its unlocking position. 
         [0006]    The release of the plunger automatically physically blocks the extended bolt so as to prevent externally-applied force from thrusting the bolt back into the lock case. The plunger may be spring-loaded or otherwise biased towards its extended operational position. 
         [0007]    According to another general aspect, there is provided a swing bolt lock comprising a swing bolt rotatable between locking and unlocking positions, a blocking member for selectively preventing rotation of the swing bolt, and a relocking mechanism engageable with one of said swing bolt and said blocking member to block said swing bolt from rotating to said unlocking position thereof when the lock is subject to a physical attack. 
         [0008]    According to another general aspect, there is provided a relocking mechanism for automatically locking a lock in a secure locked state when subject to a physical attack, the lock having a housing mounted to a door defining a spindle hole, the lock having a bolt moveable between a locking and an unlocking position; the relocking mechanism comprising: a plunger normally held in a retracted position by a breakaway member disposed to receive the force of an impact attack through the spindle hole of the door, the force of the impact attack causing the breakaway member to release the plunger which is then free to move under the action of a biasing member to an extended position in which the plunger physically blocks the movement of the bolt to the unlocking position. 
         [0009]    According to a still further general aspect, there is provided a swing bolt lock comprising a swing bolt mounted in a housing adapted to be mounted to a door having a spindle hole defined therethrough, the swing bolt being pivotable between a locking and an unlocking position, a blocker movably mounted in said housing towards and away from the swing bolt for selectively blocking or allowing rotation of the swing bolt during normal operation, and a relocking mechanism for automatically locking the swing bolt in a secure locked state when the lock is subject to a physical attack, the relocking mechanism comprising a first member connected in force transmission relationship to the housing such that externally-applied forces against the housing through the spindle hole of the door are transmitted to the first member, and a second member having an abutting surface for engagement with the swing bolt, the abutting surface of the second member physically blocking the swing bolt from moving to the unlocking position when the first member is moved from an initial default position to an operational position under the externally-applied forces. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0010]    Reference is now made to the accompanying figures, in which: 
           [0011]      FIG. 1  is a side view illustrating internal components of a so-called swing or rotary bolt lock assembly mounted on the inner face of a lock cover of the lock housing, the internal components including among others a bolt and a relocking mechanism for automatically blocking movement of the bolt in the event of a physical attack against the lock; 
           [0012]      FIG. 2  is a side view of the lock cover after a physical attack, the plunger of the relocking mechanism being biased to an operational position in which the plunger extends into the path of the bolt to maintain the lock in a secure locked state; 
           [0013]      FIG. 3  is a top cross-section of the lock assembly illustrating the relocking mechanism in a retracted non-operational default state; 
           [0014]      FIG. 4  is a top cross-section of the lock assembly after a physical attack and illustrating the relocking mechanism in its operational position to physically block the bolt from pivoting to its unlocking position, thereby holding the lock assembly in its secure locked state; 
           [0015]      FIG. 5  is a rear view of a lock case of a swing bolt lock having a cut away section defined in the lock case to provide a deformable member adapted to block the swing bolt blocking member when the lock is subject to an attack; 
           [0016]      FIG. 6  is a section view of the swing bolt lock shown in  FIG. 5  illustrating the lock in a locked position before the deformation of the deformable member; 
           [0017]      FIG. 7  is a section view of the swing bolt lock shown in  FIG. 5  illustrating the lock in a locked position with the deformable member deformed to block the swing bolt blocking member, thereby preventing unlocking of the lock; 
           [0018]      FIG. 8  is a perspective view of a swing bolt lock assembly illustrating another embodiment of a relocking mechanism comprising a fly away member and a spring-loaded wire form blocker; 
           [0019]      FIG. 9  is a section view of the swing bolt lock assembly shown in  FIG. 8  illustrating the fly away member trapped in position between a card and the lock case; 
           [0020]      FIG. 10  is a section view of the swing bolt lock assembly shown in  FIG. 8  with the fly away member released; and 
           [0021]      FIG. 11  is a section view of the swing bolt lock assembly shown in  FIG. 10  with the spring-loaded wire form blocker released into a notch defined in the swing bolt of the lock. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]      FIGS. 1 to 4  illustrate a relocking mechanism  22  for holding a locking assembly  10  in a secure locking state in the event of a physical attack. As shown in the Figures, the relocking mechanism  22  can be incorporated in a so-called swing bolt lock assembly  10  having a swing bolt  18  mounted for pivotal movement between locking and unlocking positions. It is however understood that the relocking mechanism  22  could be adapted and integrated to other types of lock, including locks having linearly reciprocable bolts (e.g. a deadbolt). 
         [0023]    The lock assembly  10  is adapted to be mounted to a safe door (not shown) of a safe (not shown). However, it is understood that the lock assembly could be mounted to other types of closure. As will be seen hereinafter, the relocking mechanism  22  is particularly designed to resist physical attacks with a hammer and metal rod or punch through a spindle hole defined in the safe door for receiving a dial spindle and/or electronic wires required to input combination from a front input unit (not shown) to the lock case assembly  10 . 
         [0024]    The lock assembly  10  comprises a housing  12  including a lock case  14  ( FIGS. 3 and 4 ) and a lock cover  16  adapted to be assembled together to define an enclosure for housing the internal components of the lock assembly  10 . It is noted that the lock assembly  10  can be installed with either the lock cover  16  or the lock case  14  mounted against the inner surface of the safe door. Accordingly, the relocking mechanism  22  can be designed to resist external forces transmitted to both the lock cover  16  and the lock case  14  (i.e. the relocking mechanism  22  can be operational irrespectively of the mounting orientation of the lock on the safe door). 
         [0025]    The bolt  18  of the lock assembly  10  projects outwardly from a front end of the housing  12  and is mounted on an axle  20  for pivotal movement between locking and unlocking positions. A motor or other actuation device (not shown) powered by battery or any other source of power may be mounted in the housing  12  to actuate a reciprocable blocking member  19  to selectively allow the bolt  18  to rotate between its locking and unlocking positions, as is well known in the art. The various lock components limiting the swing bolt  18  between its locking and unlocking positions are not material to the operation of the relocking mechanism  22  and will thus not be herein described. 
         [0026]    The relocking mechanism  22  generally comprises first and second members for respectively receiving the impact forces and blocking the bolt. As best shown in  FIGS. 3 and 4 , the second member may comprise a plunger  24  slidably mounted in a recess  26  defined in the external face of the lock cover  16 . An opening  25  is defined in the bottom surface of the recess  26  to allow the plunger  24  to project into the internal volume of the housing  12 . The plunger  24  has a head portion  24   a  and a shaft portion  24   b.  The head portion  24   a  is in sliding contact with the wall of the recess  26  and the shaft portion  24   b  is engaged in the opening  25 . A biasing member  28 , a compression spring in the illustrated embodiment, axially urges the plunger  24  towards an extended position ( FIG. 4 ) in which the plunger  24  projects inside the housing  12 . It is understood that the biasing member  28  could take various forms including but not limited to a leaf spring, a tension spring, magnets etc. According to the illustrated embodiment, the biasing member  28  is received at one end thereof in a recess defined in the head portion  24   a  of the plunger  24 . The other end of the biasing member  28  rests against the inner face of a cap  30  securely mounted to the external face of the rear cover  16  to close the recess  26  once the plunger  24  and the biasing member  28  have been loaded therein. 
         [0027]    The first member of the relocking mechanism  22  may comprise a breakaway or pull-away member  32  normally engaged with the plunger  24  to hold the same in a retracted non-functional default position ( FIGS. 1 and 3 ) against the biasing force of the biasing member  28 . In this retracted position, the plunger  24  clears the path of the bolt  18 , thereby allowing for normal operation of the bolt  18  between its locking and unlocking positions. 
         [0028]    As best shown in  FIG. 1 , the breakaway member  32  can, for instance, take the form of a deformable metal wire form mounted to the internal face of the lock cover  16 . The term “breakaway member” is herein intended to generally refer to any types of member that could be used to normally hold the plunger  24  and automatically release it when subject to a direct or indirect impact force, as will be seen hereinafter. The breakaway member  32  is positioned on the internal face of the lock cover  16  such that a distal end portion thereof extends through an open-ended horizontal slot  33  intersecting the opening  25  receiving the shaft portion  24   b  of the plunger  24 . The horizontal slot  33  acts as a localization aid to ensure proper positioning of the breakaway member  32  relative to the plunger  24  (i.e. it ensures that the breakaway member  32  extends across the path of the plunger  24 ). 
         [0029]    As shown in  FIGS. 1 and 3 , the plunger  24  can thus be preloaded against the breakaway member  32  with the biasing member  28  urging the tip of the plunger  24  against the breakaway member  32 . In other words, the breakaway member  32  extends on the internal face of the lock cover  16  directly in front of the plunger  24  to normally hold the same in its retracted position against the biasing force of the biasing member  28 , thereby providing for the normal operation of the bolt  18  by the driving components of the lock assembly  10 . 
         [0030]    As shown in  FIGS. 1 and 2 , the breakaway member  32  has first and second spaced-apart points of attachment  38  and  40  to the lock cover  16 . The breakaway member  32  can be riveted, soldered or otherwise connected in force transmission relationship to the lock cover  16 . The first point of attachment  38  is provided on a horizontal segment of the breakaway member  32  at a location spaced-apart from the plunger  24 . The second point of attachment  40  is provided on a vertical segment of the breakaway member  32  at one end thereof opposite the plunger  24 . The horizontal and vertical segments of the breakaway member  32  are respectively received in horizontal and vertical localization slots  42  and  44  defined in wire holding portions projecting inwardly from the internal face of the lock cover  16  and configured for accommodating the first and second points of attachment  38  and  40 , thereby not only ensuring proper positioning of the breakaway member  32  relative to the plunger  24  but also relative to the potential points of attack of the lock assembly  10 , as will be seen hereinafter. 
         [0031]    One potential point of attack on the lock assembly  10  is the spindle hole defined in the safe door. The relative location of the spindle hole when the lock assembly  10  is mounted to a door is depicted by circled area  47  in  FIG. 1 . It can be appreciated from  FIG. 1 , that the breakaway member  32  is generally aligned with this potential zone of attack. Indeed, the vertical segment of the breakaway member  32  extends substantially centrally across the circled area  47 . The potential zone of attack provided by the spindle hole is disposed between the first and second points of attachment  38  and  40  of the breakaway member  32 . In fact, the second point of attachment  40  can be located immediately next or in the zone of attack identified by circled area  47  in  FIG. 1 . 
         [0032]    As shown in  FIGS. 1 and 2 , the lock cover  16  has a thinned or weak cover section  48  provided between the plunger  24  and the first and second points of attachments  38  and  40 . The first and second point of attachments  38  and  40  of the breakaway member  32  are both located on the same side of the thinned or weak cover section  48  (the right-hand side in  FIG. 1 ), that is on a side opposite to the side on which the plunger  24  is disposed. It is also noted that the first and second points of attachment  38  and  40  and the identified potential zone of attack (i.e. circled area  47  in  FIG. 1 ) are disposed on the same side of the lock cover  16  relative to the thinned cover section  48 . As shown in  FIGS. 2 and 4 , the lock cover  16  is designed to break along the thinned or weak cover section  48  when an impact force exceeding a predetermined threshold value is transmitted to or is directly applied on the inside of the lock cover  16 . Accordingly, if the lock assembly  10  is mounted to the internal side of a door with the lock case  14  against the internal face of the door and if the lock assembly  10  is physically attacked with a hammer and metal rod or punch through the spindle hole in the safe door, the lock cover  16  will break along the thinned cover section  48 , thereby allowing the portion of the lock cover  16  which receive the impact force (the right-hand side portion in  FIG. 4 ) to move out of position, as depicted by arrow  50  in  FIG. 4 . Since the points of attachment  38  and  40  of the breakaway member  32  are all provided on the broken portion of the lock cover  16 , the breakaway member  32  will move jointly with the broken portion of the lock cover  16 , thereby causing the free distal end portion of the breakaway member  32  to pivot or move away from the plunger  24 , as best seen in  FIG. 4 . This allows the plunger  24  to move to its extended position under the biasing force of the biasing member  26 . As can be appreciated from  FIGS. 2 and 4 , in its extended position, the plunger  24  physically blocks the bolt  18  from being rotated in a counter clockwise direction towards its unlocking position. 
         [0033]    If the lock assembly  10  is mounted with the lock cover  16  against the door, the alignment of the breakaway member  32  with the spindle hole between the two points of attachment  38  and  40  will cause the breakaway member  32  to be ripped out of the lock cover  16  under the direct impact of the punch, thereby automatically releasing the plunger  24  to block the bolt  18  against movement as detailed hereinabove. 
         [0034]    In view of the foregoing, it is apparent that the above described relocking mechanism  22  has a reversible design providing for the mounting of the lock assembly  10  with either the lock case  14  or the lock cover  16  against the door. If the lock assembly  10  is only intended to be mounted on the door with the lock case  14  against the door, the breakaway member  32  could only include the horizontal segment (i.e. in this case there is no need for the breakaway member to be aligned with the zone of impact). 
         [0035]      FIGS. 5 to 7  illustrate another embodiment of a swing bolt relocking mechanism. This embodiment is characterized by a first member which is provided in the form of a deformable member  102  which is adapted to deform into the path of the swing bolt blocking member  119  to prevent the blocking member  119  from moving out of the path of the swing bolt  118 , thereby physically blocking movement of the swing bolt  118 . As shown in  FIG. 5 , the deformable member  102  can be integrated into the lock case  114  by cutting away a section of the lock case  114  adjacent to the blocking member  119  in such a way as to cause a portion of the lock case  114  (i.e. the deformable member  102 ) to deform when the lock is attacked through the spindle hole in the door using a hammer and a punch. As shown in  FIG. 6 , under normal circumstances, the deformable member  102  clears the path of the blocking member  119 , thereby allowing the blocking member  119  to linearly translate back and forth to selectively prevent or allow the rotation of the swing bolt  118 . However, in the event of a physical attack, the deformable member  102  will under the impact forces on the case  114  bend into the path of the blocking member  119 , thereby preventing withdrawal thereof. As shown in  FIG. 7 , once deformed, the deformable member  102  prevents the blocking member  119  from moving away from the swing bolt  118 , thereby indirectly blocking the bolt  118  in its locked state. This relocking mechanism takes advantage of the already existing blocking member  119  of the lock mechanism to prevent unauthorized opening of the lock (i.e. the blocking member corresponds to the second member of the relocking mechanism). 
         [0036]      FIGS. 8 to 11  illustrate a further embodiment of a relocking mechanism which is characterized by a first member which is provided in the form of a fly away member  232  which is releasably or detachably mounted inside the lock case  214  for normally holding the second member of the mechanism in this case a spring-loaded wire form blocker  224  away from the swing bolt  218  of the lock. As shown in  FIGS. 8 and 9 , the fly away member  232  can be trapped between the lock case  214  and a card  215  mounted to the lock case  214  with the spring-loaded wire form blocker  224  engaged there under. Alternatively, the fly away member  232  could be trapped between the lock case  214  and the lock cover (not shown). In the event of an attack, the impact forces applied on the lock case  214 , cover or card  215  through the spindle hole in the door will cause the lock case  214 , cover or card  215  to deform or, alternatively, the detachment of the card  215  from the case  214 , thereby releasing the fly away member  232 . As shown in  FIGS. 10 and 11 , the release of the fly away member  232  will, in turn, cause the spring-loaded wire form blocker  224  to automatically fall into a notch  233  defined in the swing bolt  218 , thereby retaining the bolt  218  from rotating. A blocking bolt  235  extends from the inner face of the lock case  214  to prevent the wire form blocker  224  from being bent by the rotation of the swing bolt  218 . 
         [0037]    The above descriptions are meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention herein disclosed. For example, the breakaway member could be provided in the form of a frangible member adapted to be broken away so as to release the plunger when ever a force exceeding a predetermined value is transmitted to the lock housing. Also, the breakaway member itself could be used to block the movement of the bolt instead of the above described pre-loaded plunger arrangement. For instance, the relocking mechanism could comprise a breakaway, frangible or brittle member for interlocking the bolt with the lock case by wedging itself between the lock case wall and the bolt when the lock assembly is physically or mechanically attacked through the door spindle hole with a hammer and punch. The lock cover  16  would bend along the thinned section  48  as shown in  FIG. 4 , thereby breaking and/or pivoting the breakaway member allowing the massive end of the breakaway member to progress into the path of the bolt, thus securing the lock in the locked state. Still other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.