Abstract:
A lock including a housing having an opening for a locking bolt, a locking bolt movable between a locked position and an unlocked position, an actuator positioned within the housing, and a rotary blocking device that prevents the locking bolt from moving to the unlocked position is disclosed. The lock may optionally include a tamper resistant mechanism that is designed such that attempting to forcibly move the locking bolt from the locked position to the unlocked position while the actuator remains in the locked condition causes the locking bolt to engage the tamper resistant mechanism.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. provisional patent application Ser. No. 61/896,907, filed Oct. 29, 2013, the entirety of which is herein incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to locks having a rotary blocking device that prevents a bolt from moving to an unlocked condition and an optional tamper resistant mechanism that prevents unauthorized access to a safe when using force. 
         [0004]    2. Description of the Related Art 
         [0005]    Doors of safes, vaults, strong rooms, container and similar security closures (collectively called “safes” in this application) usually have at least one and preferably several safe bolts that reciprocate from a non-locking position to an extended locking position. In the locking position, the safe bolts extend from the safe door into the adjacent safe walls. When the safe has more than one bolt, bolt works connect the bolts. The bolt works include linkages that move the safe bolts simultaneously when a user turns a handle. A locking device cooperates with the bolt works to secure the safe bolts in their extended locking position. 
         [0006]    Swing bolt or rotary bolt locking devices mount a bolt for pivoting between locked and unlocked positions. This application refers to the swing bolt within the locking device as the “bolt,” “swing bolt,” or “locking bolt.” The bolts that secure the safe door to the rest of the safe are called “safe bolts.” In the locked position, part of the locking bolt projects out of the housing and interferes with a portion of the mechanical bolt works, thereby preventing the bolt works from moving the safe bolts to the unlocked position. When the user enters the correct combination, the lock mechanism allows the locking bolt to pivot to the unlocked position within the housing, thus allowing the user to open the safe door. 
         [0007]    Rectilinear bolt locking devices operate in a similar manner. In particular, rectilinear bolt locking devices mount a bolt within a housing for moving between locked and unlocked positions. Thus, instead of pivoting like rotary bolts, linear bolts slide into and out of the locking device housing. When the user enters the correct combination, the lock mechanism allows the locking bolt to slide into the housing. For purposes of explanation and example, the remainder of the background discussion will focus on rotary type locking devices. 
         [0008]    In general, a handle on the outside of the safe connects to the bolt works. Rotating the handle initiates movement of the bolt works. If the user enters the correct combination which unlocks or releases the locking bolt, the bolt works can pivot the rotary bolt so that the rotary bolt does not project from the housing. This unlocked position permits the bolt works to continue moving the safe bolts to the unlocked condition, allowing the operator to open the safe. If, however, the rotary bolt is locked, the rotary bolt blocks movement of the bolt works, preventing the bolt works from withdrawing the safe bolts. U.S. Pat. Nos. 5,134,870 and 5,142,890 to Uyeda describe safes using rotary bolts. 
         [0009]    The locking mechanism within the lock housing blocks the bolt from pivoting to the unlocked position. Uyeda utilizes a linear solenoid within the housing. Uyeda discloses a solenoid plunger that directly engages the locking bolt. Alternatively, the solenoid plunger engages a locking plate that projects against the bolt. When the plunger or plate engages the bolt, the bolt normally cannot rotate to an unlocked position. 
         [0010]    An electronic combination entry system controls the solenoid. Typically, the user enters the combination through a digital input pad. U.S. Pat. No. 5,887,467 to Butterwerk, entitled “Pawl and Solenoid Locking Mechanism,” is an example of a lock that uses an electronic key pad on a rotary handle. Rotary input through a dial also can generate an output. Internal circuitry senses entry of the correct combination and sends an electrical signal to the solenoid. The signal causes the solenoid to withdraw a plunger, which, in turn, allows the locking plate to disengage the locking bolt. The user rotates a handle which in turn manipulates the bolt works. Part of the bolt works pushes on the locking bolt to rotate the bolt about a shaft to the unlocked position. The bolt works then withdraws the safe bolts. 
         [0011]    Applying sufficient force, such as pounding, jostling, twisting, vibration, or other manipulation, on a locked handle of a safe with a swing bolt lock that is engaged with a plunger controlled by a linear solenoid can sometimes open the safe. This results because the solenoid must be relatively small to fit within the lock housing correspondingly, the plunger is also small and weak. Consequently, sufficient force applied to the handle breaks the plunger. Once the plunger breaks, or is vibrated out of the way, the locking plate moves freely, which allows the swing bolt to pivot open. The bolt works can then be manipulated to withdraw the safe bolts to open the safe. 
         [0012]    Uyeda and others have proposed a solution to this problem by using a “safety key” design. The bore of the swing bolt, which rotates about a shaft or axle, is elongated. The elongated opening can move along the bore when one applies a force from the handle through the bolt works on the swing bolt. Thus, the swing bolt can move laterally. Lateral movement causes a notch on the periphery of the swing bolt to engage a safety key in the lock housing. This prevents further force being applied to the swing bolt from transferring to the solenoid plunger or locking plate. 
         [0013]    Uyeda also discloses a leaf spring that biases the swing bolt and the bore to a normal position relative to the shaft within the bore. When an unauthorized user tries to force the handle without first entering the correct combination, the notched bolt pushes against and engages the safety key in the housing preventing entry. 
         [0014]    The mechanism disclosed by Uyeda is complex and costly to build and assemble. Others have simplified the mechanism, but the structure that biases the swing bolt relative to the shaft or axle remains complex. For example, one conventional swing bolt has a bolt plate mounted in a groove in the swing bolt. The plate has an opening over part of the elongated opening in the swing bolt. A spring within the bolt biases the opening in the plate to one end of the elongated opening. When force is applied to the bolt to cause it to pivot about the solenoid locking plate, the bolt plate slides on the bolt against the spring until the opening in the bolt plate is at the other end of the elongated opening in the swing bolt. This shifts the swing bolt sufficiently to cause the notch of the periphery of the swing bolt to engage the key in the lock housing. The construction of the swing bolt with the sliding plate and internal spring is complex. Assembly is time consuming and costs are high. Furthermore, since the spring is within the bolt, a bearing is created between the shaft and the lock housing instead of between the swing bolt and the shaft, thereby reducing the potential life cycle of the lock. 
         [0015]    An alternative design of a lock assembly is disclosed in U.S. Pat. No. 6,786,519 to Gartner. Gartner discloses a solenoid mounted within a housing and a plunger on the solenoid that engages a locking plate. When the lock is in the locked condition, the locking plate engages the locking bolt, preventing the swing bolt from pivoting. When a user enters the correct combination, the plunger disengages the locking plate so that the latter is free to slide out of its engagement with the locking bolt. If an unauthorized user applies sufficient force to the handle through the bolt works against the swing bolt, the intersection of the swing bolt and the locking plate becomes an axis of rotation. The swing bolt rotates slightly on that axis because the opening in the swing bolt through which the shaft extends is elongated. The elongation permits some lateral movement of the swing bolt relative to the shaft. As a result, a single notch on the swing bolt periphery engages a safety key on the housing preventing access. 
         [0016]    Unfortunately, safety key mechanisms such as the one disclosed in &#39;519 to Gartner provide insufficient protection against unauthorized access into the safe. Notably, a thin piece of shim stock such as steel may be positioned between the single notch and the safety key when the locking bolt is in the locked position. When the locking bolt is forcibly rotated, the thin shim acts as a “camming” surface, allowing the single notch to bypass the safety key element. As a result, force from the swing bolt may once again be applied against the solenoid plunger or locking plate, potentially resulting in damage to the plunger or solenoid within the lock housing. 
         [0017]    Solutions such as those disclosed by Gartner and Uyeda that utilize linear solenoids to control movement of a plunger into and out of a locking bolt or a locking plate provide insufficient protection against “shock.” In the locked position, the plunger connected to the linear solenoid is extended such that it engages with, for example, a rotary locking bolt. In the unlocked position, the plunger retracts such that it no longer engages with the locking plate, thereby allowing the locking bolt to freely rotate. A problem arises when the linear solenoid, an electromagnetic device, receives a “shock.” Shock can be a result of physical tampering, applied force, vibration, etc. Typically, when a linear solenoid receives a shock, it causes an extended shaft (or in this case, the plunger) to retract in reaction to the shock. This poses a problem because the retraction of the plunger without entering the correct combination would effectively allow unauthorized access into the safe despite the addition of a notch and safety key feature. 
         [0018]    U.S. Pat. No. 8,261,586 to Gartner, the entirety of which is incorporated herein, addresses the foregoing issues related to insufficient protection against “shock.” However, the lock disclosed in the &#39;586 patent includes many piece parts, is expensive to make and difficult to assemble. For example, in order to block the rotary locking bolt the cam engagement means include both a D-shaped tab member and a stop member with radially extending flange. The locking bolt is blocked from underneath the bolt when the D-shaped tab member rotates to a flat portion and the bolt slides over the stop. Further, a compression spring couples a pin on the locking bolt to a pin on the housing which biases the bolt in the locked position. 
         [0019]    Accordingly, there is a need for continued improvements in blocking devices for use with locks that simplifies the assembly by reducing the number of parts to be more cost-efficient, changes the method of blocking and can reliably block access under force and shock. 
       BRIEF SUMMARY OF THE INVENTION 
       [0020]    The present invention solves the foregoing problems by providing a lock including a housing having an opening for a locking bolt, a locking bolt movable between a locked position and an unlocked position, and an actuator positioned within the housing. An optional tamper resistant mechanism in the housing is also provided. The actuator includes a locked condition engaging the locking bolt and an unlocked condition freeing the locking bolt to move to the unlocked position. The optional tamper resistant mechanism is designed such that attempting to forcibly move the locking bolt from the locked position to the unlocked position while the actuator remains in the locked condition causes the locking bolt to engage the tamper resistant mechanism. 
         [0021]    In another aspect of the present invention, the actuator is operably coupled to a rotatable cam engagement means with a flange member for blocking the locking bolt. The flange member is configured to rotate between a first blocking position that blocks the locking bolt and a second position which allows the locking bolt to bypass it and unlocked position of the locking bolt. A cam return spring biases the rotatable cam engagement means in the first blocking position and a locking bolt return spring biases the locking bolt in the locked position 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is a top plan view of one embodiment of a lock according to the invention. 
           [0023]      FIG. 2  is a side view of the lock depicted in  FIG. 1 . 
           [0024]      FIG. 3  is perspective view of one embodiment of a lock according to the invention. 
           [0025]      FIG. 4  is a top view of the lock of  FIG. 3  illustrating a locking bolt in the locked position. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]      FIG. 1  is a perspective view of one embodiment of the present invention, broadly including lock  10  including a housing  12  and a locking bolt  40  with an optional tamper resistant mechanism  95 . Housing  12  is commonly brass or another reasonably hard, nonmagnetic metal that can be cast. Housing  12  has a top and bottom  14  and  16  and two sides  18  and  20 . The use of “top,” “bottom,” and “sides” relates to the orientation of the lock in the figures. Each side could become a top or bottom depending on the orientation of the lock in the locked container. As  FIG. 1  shows, housing  12  is may be rectangular with curved corners, a common, standard-shaped housing but as those of skill in the art may appreciate the shape of the housing may vary and still be within the scope of the invention. 
         [0027]    Housing  12  includes base  13  having inside wall  24  and cover  15 . Base  13  of housing  12  attaches to the door of a safe or other secure container. Cover  15  may be removable from housing  12  for repairing various components of lock  10 . Cover  15  includes a plurality of openings  27 ,  28 ,  29  therethrough that receive a like number of fasteners that extend through openings and are threaded into threaded openings in the door of the safe. Thus, the fasteners secure lock  10  to a safe, a door or other type of container. The spacing and number of openings  27 ,  28 ,  29  is standardized by different safe manufacturers and vary from manufacturer to manufacturer and enable that manufacturers&#39; locks to be compatible with various safes. 
         [0028]    Referring now to  FIGS. 1-4 , a locking bolt  40  mounts in housing  12 . In one embodiment, locking bolt  40  is a rotary bolt having a generally D-shape in cross-section. However, it should be understood that various other shapes of locking bolts  40  are contemplated and within the intended scope of the present invention. A shaft receiving opening  42  is positioned near the center of rotary bolt  40 . Shaft receiving opening  42  is configured to receive a shaft or  43  that mounts within the housing. The shaft mounts in first and second sleeves (not shown) located on the inside top and bottom walls of the housing  12 . Shaft receiving opening  42  is generally round and has a diameter that is slightly larger than the diameter of shaft  43 . Shaft receiving opening  42  of locking bolt  40  fits onto the shaft  43 , allowing locking bolt  40  to rotate about the shaft. Thus, a bearing means is formed between opening  42  of locking bolt  40  and shaft, which remains generally stationary as locking bolt  40  rotates. 
         [0029]    Locking bolt  40  is illustrated in  FIGS. 1 and 4  in a locked position. In the locked position, extended portion  44  of locking bolt  40  extends outside locking bolt opening  46 . Locking bolt opening  46  is an indentation in top wall  14  of housing  12  that is typically formed when the housing is cast. Cover  15  may have a narrow flange (not shown) that extends into and forms a boundary or wall of opening  46 . In operation, locking bolt  40  rotates to an unlocked position in which extended portion  44  of locking bolt  40  retracts within housing  12 . The movement of locking bolt  40  between the locked and unlocked positions will be described in more detail with reference to  FIGS. 3 and 4 . 
         [0030]    Locking bolt  40  includes an aperture  45  therein. A bolt return spring  46  includes a central spring portion  47 , a biasing portion  48  and a pin portion  49 . The central spring portion  47  is positioned on and surrounds shaft  46 . Biasing portion  48  stretches from central spring portion  47  and engages a shelf of housing  12  that extends upward from inside wall  24 . Pin portion  49  stretches from the opposite end of central spring portion and is received by bolt aperture  45 . Thus, tension from spring  46  biases locking bolt  40  counterclockwise with extended portion  44  of bolt  40  in the locked position. 
         [0031]    An actuator  60  mounts inside housing  12 . Many different types of actuators may be used including, but not limited to, motors, rotary solenoids, electromechanical rotary devices, and electromagnetic rotary devices. As an exemplary embodiment, actuator  60  will be described as a rotary solenoid throughout the remainder of this disclosure. As best seen in  FIGS. 3 and 4 , rotary solenoid  60  mounts in a cavity  62  within housing  12 , which is formed by several walls extending upward from inside wall  24  of base  13 . The walls forming cavity  62  are typically part of the casting that forms housing  12 . Attached to rotary solenoid  60  via a rotary shaft  61  is a cam engagement means  65  including an elongated flange member  66  extending radially therefrom. Cam return spring  82  biases cam engagement means  65  in the “blocking” position  68  as shown in  FIG. 4 . Elongate flange member  66  engages a surface of locking bolt  40  to maintain the bolt  40  in the locked position. Circuitry within a circuit board (not shown) cooperates with the combination entry device discussed previously. When the user enters the correct combination, the circuitry signals solenoid  60  to rotate flange member  66  by a predetermined amount. As a result, the cam engagement means with flange member  66  rotates and disengages with locking bolt  40 , allowing the bolt to rotate clockwise to the unlocked position. 
         [0032]    Referring now to  FIGS. 3 and 4 , how rotary solenoid  60  controls movement of locking bolt  40  will now be described. Cam engagement means  65  includes a central portion having an opening therein that is mounted on a rotary shaft operably coupled to the output of rotary solenoid  60 . Cam engagement means  65  also includes an elongate flange member  66  extending radially outward therefrom. In the blocking position, elongate flange member  66  is received with a groove or stop  63  in housing  12 . Flange member engages a portion of locking bolt preventing it from moving into an unlocked position. Rotary solenoid  60  rotates cam engagement means  65  between a locked position where the tip of locking bolt engages the elongate flange member  68  and an unlocked position where the elongate flange member disengages the tip of locking bolt  40  allowing the locking bolt to bypass elongate flange member  66  and the locking bolt is able to freely rotate from the locked position as shown in  FIG. 4  to the unlocked position as shown in  FIG. 3 . 
         [0033]    As shown in  FIG. 4 , locking bolt  40  is in the locked position with bolt  40  extended outside housing  12 . If the user fails to enter the correct combination or attempts to open the door without entering a combination, the elongate tab remains blocking locking bolt  40  so that locking bolt cannot freely move. Attempting to rotate the handle causes locking bolt  40  to push against elongate flange member  66 . Tamper resistant mechanism  95 , shown as teeth, prevents further rotation of locking bolt  40  even when additional pressure is exerted on the handle, as will be described in further detail to follow. An authorized user then will reenter the correct combination. 
         [0034]      FIG. 3  is a perspective view of lock  10  illustrating locking bolt  40  rotated to the unlocked position. In particular, after entry of the correct combination, rotary solenoid  60  rotates cam engagement means such that elongate flange member  66  is no longer in engagement with locking bolt  40 . Because there is no longer an interference between elongate flange member  66  and locking bolt  40 , the bolt may rotate toward the unlocked position as illustrated in  FIG. 3 . In the unlocked position, extended portion  44  of locking bolt  40  rotates such that it is completely within housing  12 . 
         [0035]    As locking bolt  40  rotates clockwise toward the unlocked position, bolt return spring  46  creates a spring tension that urges locking bolt  40  in the counterclockwise direction. Thus spring  46  biases locking bolt  40  to return to the locked position when a user releases the handle (not shown). 
         [0036]    Lock  10  also includes cam return spring  82  disposed between the cam engagement means and rotary solenoid  60 . Spring  82  includes an arm  84  that rests on the inside of housing  12 . When cam engagement means  65  rotates from the locked to the unlocked position, spring  82  creates a spring tension as would be appreciated by one skilled in the art. Thus, spring  82  biases cam engagement means  65  and elongate flange member  66  in the blocking position  68 . When rotary solenoid  60  ceases to transmit a signal that allows locking bolt  40  to unlock by the mechanism described above, cam engagement means  65  and elongate flange member  66  will automatically return back to the locked position. 
         [0037]      FIG. 3A  is a top view of a portion of lock  10  showing a second aspect of the present invention.  FIG. 3A  depicts locking bolt  40  in the locked position. As shown in phantom lines in  FIG. 3A , housing  12  includes rear sleeve  90  positioned towards the back side of locking bolt  40  and is configured to receive shaft  43 . Rear sleeve  90  is elongated, having a width dimension W that is less than the length dimension L. Rear sleeve  90  also includes groove  92  configured to receive compression spring  94 . A first end of compression spring  94  pushes against the back portion of groove  92 . A second end of compression spring  94  pushes against an outer surface of shaft  43 , positioning shaft  43  in a normal operating position within rear sleeve  90 . In the normal position, locking bolt  40  rotates without obstruction between the locked and unlocked positions when rounded portion  70  of flange member  68  disengages with receiving groove  78  in locking bolt  40 . 
         [0038]    As can be seen in  FIG. 5 , wall  22  of cover  15  includes a sleeve. The sleeve in wall  22  is configured to receive a second end of shaft  43 , and includes a compression spring that pushes against the outer surface of shaft  43  to maintain the shaft in the normal position within the sleeve. Thus shaft  43  has two springs that bias it in the normal position. It is beneficial to have two springs that bias shaft  43  in the normal position because two springs keep the shaft substantially straight and create a bearing between shaft  43  and locking bolt  40  instead of, for example, between shaft  43  and housing  12 , which extends the life cycle of the lock. 
         [0039]    Referring now to  FIG. 3 , a top view of a portion of lock  10  in accordance with one embodiment of the present invention shows locking bolt  40  in the unlocked position. Locking bolt  40  has rotated clockwise about shaft  43  such that extended portion  44  of locking bolt  40  is disposed within housing  12 . As locking bolt  40  rotates about shaft  43 , the position of shaft  43  within rear sleeve  90  remains relatively constant (i.e., shaft  43  remains in the “normal” position) due to the force of compression of spring  94  on the outer surface of shaft  43 . Therefore, as locking bolt  40  rotates toward the unlocked position, there is enough of a clearance between a plurality of teeth positioned in both locking bolt  40  and housing  12  to allow locking bolt  40  to rotate freely between the locked and unlocked positions without obstruction. 
         [0040]    Referring again to  FIG. 4 , the “tamper-resistant” mechanism  95  of the present invention is shown. In particular, locking bolt  40  includes a plurality of teeth  95  that are configured to engage with mating teeth  98  in housing  12  positioned near locking bolt opening  46 . In one embodiment, the clearance between teeth  95  and teeth  98  is between about 0.005 inches and about 0.015 inches. If a user attempts to force locking bolt  40  to the open position, a force F is applied through the handle of the bolt works (attached to the front of a container onto which the locking bolt  40  is mounted) on locking bolt  40 . Because the correct combination has not been entered, elongate flange member  68  remains in contact with the tip of locking bolt  40  as shown in  FIG. 4 . The force from the handle applies a clockwise torque on locking bolt  40 , which in turn causes a force to be exerted on shaft  43 . The force exerted on shaft  43  is in the direction of the elongated portion of rear sleeve  90  and moves against the force produced by compression spring  94 . As a result, shaft  43  compresses spring  94  and moves toward the right side of rear sleeve  90 . 
         [0041]    When the user attempts to force locking bolt  40  to the open position, locking bolt  40  moves to the right sufficiently so that teeth  95  of locking bolt  40  engage with teeth  98  in housing  12 . Teeth  98  are generally formed as part of the cast brass housing  12 , although workers skilled in the art will appreciate that the teeth may be formed from other materials and attached to housing  12 . Furthermore, it becomes apparent that even if someone attempts to insert a thin piece of shim stock in between teeth  96  and  98  to “override” the tamper-resistant mechanism, the shim stock will deform as the teeth engage with one another. 
         [0042]    When locking bolt teeth  95  engage housing teeth  98 , locking bolt  40  is prevented from rotating clockwise. As  FIG. 4  shows, locking bolt  40  remains in the locked position. This limits the force that locking bolt  40  applies on elongate flange member  68  which is in contact with locking bolt  40 . Consequently, locking bolt  40  does not apply enough force to elongate flange member  68  to shear it off and therefore allow unauthorized access into the safe. A user attempting to force the lock can not rotate locking bolt  40  to the open position nor cause the bolt works to withdraw the safe locks to gain entry to the safe. 
         [0043]    Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.