Abstract:
A motorized lock for a vending machine provides a simple lever mechanism that provides two separate points of engagement between the door and the machine to resist tampering and provide for more even pull in of a gasketed door.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation of U.S. application Ser. No. 11/519,505 filed Sep. 12, 2006 now abandoned thereby incorporated by reference. 

   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   -- 
   BACKGROUND OF THE INVENTION 
   The present invention relates to vending machines and in particular to a motorized lock assembly for such vending machines. 
   Vending machines, such as may automatically dispense products to consumers, may provide a cabinet for holding the products to be dispensed and money handling machinery. The cabinet is normally covered by a lockable door that may, for example, extend over the entire front face of the vending machine, and which may seal the interior of the cabinet from the environment, often by means of a large flexible gasket extending around the perimeter of the door. 
   The lock of the vending machine door must both hold the door securely and provide for compression of the gasket to fully close the door. A common lock suitable for this purpose provides a pop-out T-handle that may be rotated to compress the gasket by drawing the handle in along a threaded shaft, and then pressed into a recess where the T-handle is prevented from further rotation and retained by a lock cylinder. Examples of such a lock are shown in U.S. Pat. No. 3,550,412, issued Dec. 29, 1970. 
   The time required to compress the gasket using a T-handle system (and conversely, to release the door by uncompressing the gasket) increases the time and cost of routine service of the vending machine, for example, to replenish stock and collect money. For this reason, motorized locks have been developed that may be triggered by a radio signal to begin unlocking the vending machine as a service person prepares for restocking, and that may automatically compress the gasket and lock the vending machine when restocking is complete as the service person completes other tasks. U.S. Pat. No. 6,581,986 describes a radio-controlled, motorized lock for vending machines that employs a bayonet that enters a slot and rotates to hold itself within the slot and then to pull the door closed, much like a T-handle system. 
   Improved security and a more uniform compression of the door gasket could be obtained through multiple locks joining the door and the cabinet. A single radio signal could coordinate these multiple locks, however, current motorized designs are prohibitively expensive. 
   SUMMARY OF THE INVENTION 
   The present invention provides a multi-point lock providing the increased security of two separate latch points, and a more uniform compression of the door gasket using a simple lever mechanism. The lever mechanism produces a hooking and pulling action that provides a large latch-throw suitable for gasketed doors, and provides high, end-stroke compression of the gasket to seal the gasket and resist unauthorized opening of the door. 
   Specifically, in a first embodiment of the present invention, a motorized vending machine lock is provided having a strike plate attached to one of a door and cabinet of the vending machine, and at least two bolts attached to an other of the door and cabinet. A single electric motor drives an actuation mechanism that, in the first operating mode, engages the bolts and strikes at spatially separated points and then draws the door against the cabinet, and in a second operating mode, releases the door from the cabinet and disengages the bolts from the strike plate. 
   Thus, it is one object of at least one embodiment of the invention to provide a cost-effective, multi-point latch using a single motor drive. 
   The spatially separated points of attachment of the bolts may be along the gasket at the edge of the door. 
   Thus, it is another object of at least one embodiment of the invention to provide improved stability in the closing of the door that reduces the need for additional door structure to manage door warping. 
   The actuator mechanism may operate in the first mode when the motor turns in a first direction, and in the second mode when the motor turns in a second direction. 
   Thus, it is another object of at least one embodiment of the invention to provide a simple two-mode locking and unlocking mechanism that requires only motor reversal to control. 
   The bolts may be pivoting hooks, having hook ends movable within a plane to engage and disengage with corresponding hook engagement points on the strike plate, and movable within the plane to extend and retract along a direction of separation of the door and cabinet. 
   Thus, it is another object of at least one embodiment of the invention to provide a simple lever mechanism that may be readily manufactured without the need for customized cam, screw, and gear elements. 
   The actuator mechanism may include a frame supporting the motor and a first and second swing arm. The first and second swing arms are pivotally attached to the frame at first ends and at second ends pivotally attached to a first pivot point on a corresponding first and second hook at a location on the hook removed from a hook portion engaging the strike plate. This attachment allows the swing arms and hooks to pivot with respect to each other through a range of acute angles. A crank may be attached to the motor providing a first and second crank end moving with actuation of the motor with a first and second drive linkage pivotally attached to corresponding crank ends and pivotally attached to second pivot points on the corresponding first and second hooks between the first pivot point and the hook portion. 
   Thus, it is an object of at least one embodiment of the invention to provide a locking mechanism that may work predominantly with pivoting linkages that are reliable, easy to manufacture, and compact to move within a single plane. 
   The swing arms may be substantially aligned in the direction of the separation of the door and cabinet when the hooks are engaged with the strike plate and the door is closed. 
   It is thus another object of at least one embodiment of the invention to provide an extremely high resistance to opening the door when the lock is closed resulting from the fact that forces of opening the door extend along the linkage aligned with that direction. This alignment compresses the swing arms against their pivot points rather than moves the swing arms against their drive linkages. 
   The hooks may engage and disengage from the hook engagement points by motion of the swing arms about pivot points substantially aligned with the corresponding hook engagement points along the direction of separation of the door and cabinet. 
   It is thus another object of at least one embodiment of the invention to provide extremely high leverage at the final stage of closure of the door, as the swing arms pivot into alignment with the closure axis, to offset the increasing force of resistance of a gasket. 
   The crank ends may be at substantially a 180 degree spacing about an axis of rotation of the crank, and the first and second drive linkages may extend symmetrically in opposite directions. 
   It is thus another object of at least one embodiment of the invention to provide a door closure system that exerts little or no side thrust on the motor. 
   The lock may include a radio link providing a signal to the motor to operate the motor in a first operating mode. 
   It is thus another object of at least one embodiment of the invention to provide a secure lock that greatly simplifies the stocking of a vending machine. 
   The invention may include an alignment guide positioning the strike plate and bolts in alignment before engagement of the bolts with the strike plate. 
   It is thus another object of at least one embodiment of the invention to accommodate possible door misalignment by correcting for that alignment during the closing process. 
   The invention may include a secondary lock holding the door closed for shipping. 
   It is thus another object of at least one embodiment of the invention to provide additional robustness during the shipping process when the cabinet may be subject to higher and/or different forces. 
   The lock may include an electric switch providing a signal indicating that the door is close enough to the cabinet for the bolts to engage the strike plate. 
   It is thus another object of at least one embodiment of the invention to allow the door to prevent misleading actuation of the lock when locking cannot occur. 
   These particular objects and advantages may apply to only some embodiments falling within the claims, and thus do not define the scope of the invention. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
       FIG. 1  is a perspective view of a typical vending machine cabinet showing a hinged door and location of the locking mechanism of the present invention; 
       FIG. 2  is an exaggerated view of motion of the hook bolts of the present invention as they engage a strike plate for drawing the door into closure; 
       FIGS. 3   a  and  3   b  are diagrams of paths of the hook ends of the hook bolts of  FIG. 2  during closure and release of the door, respectively; 
       FIGS. 4   a  and  4   b  are elevational views of the hook bolts, swing arms, and actuation arms immediately prior to engagement of the hook bolts with the strike plate and at closure, respectively, showing the high-force amplification obtained and high resistance to opening of the door provided by the locking mechanism of the present invention; 
       FIG. 5  is an exploded perspective view of the hook bolts and actuation arms as attached to a crank arm of a gear motor that may actuate both opposed hook bolts; 
       FIG. 6  is a detailed view of  FIG. 5  showing interengagement of the hook portion of the hook bolts and the strike engagement surface such as provides a highly secure interlock between the two; 
       FIG. 7  is a detailed view of  FIG. 5  showing a door switch detecting proximity of the strike plate and lock assembly and an alignment guide bringing the strike plate and lock assembly into alignment prior to locking; 
       FIG. 8  is an electrical schematic showing connection of the door switch of  FIG. 7  and gear motor of  FIG. 5  for normal actuation; 
       FIG. 9  is a figure similar to that of  FIG. 4   a  of an alternative embodiment in which secondary electrical actuators such as solenoids are used to engage the hook bolts with the strike plate; and 
       FIG. 10  is a figure identical to  FIG. 5  but for the elimination of one hook bolt and its associated mechanisms and strikeplate notch. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to  FIG. 1 , a vending machine  10  suitable for use with the present invention may include a cabinet  12 , being generally a metal box sized to hold a vending apparatus (not shown), and having an open front that may be covered by a door  14 . The door  14  may display on its front surface vending controls  18 , including product selection buttons and money handling apparatus, and may include a dispensing slot  20 . 
   The door  14  may hinge about an axis  16 , being in this example, a vertical axis aligned with a right side of the open face of the cabinet  12 , to move between a closed position covering the opening of the cabinet  12 , and an open position providing access to the interior of the cabinet  12 . A compressible gasket  26  may be attached to the periphery of the open face of the cabinet  12  or the corresponding surface of the door  14  to seal the door  14  against the cabinet  12  when the door  14  is closed. 
   During the initial stages of opening the door  17  and the latter stages of closing the door  14 , the edge of the door  14  removed from axis  16 , moves generally along a separation axis  22  tangent to the arc of motion of the left edge of the door  14 . The left edge of the door  14  may support a locking mechanism  24  as will now be described. 
   Referring momentarily to  FIG. 5 , the locking mechanism  24  of the present invention provides two different interengaging components, a strike plate  28  and a lock assembly  30 , mounted on opposite sides of the door  14  and cabinet  12 , respectively, so as to latch and unlatch the door  14  to the cabinet  12 . The strike plate  28 , mounted in this example on the cabinet  12 , provides a vertical mounting edge  34  incorporating a series of mounting holes  36 , allowing the strike plate  28  to be attached with one side affixed to the frame of the cabinet  12  to extend in a vertical plane aligned with the separation axis  22  along of the left edge of the cabinet  12 . 
   Correspondingly, the lock assembly  30  may be attached to a rail  32  forming an outer peripheral frame of the door  14  to be positioned opposite the strike plate  28  along the separation axis  22 . 
   Referring now to  FIG. 2 , a top and bottom edge of the strike plate  28  provide vertically extending strike engagement notches  38  that may be engaged by a hook end  40  of upper and lower hook arms  42   a  and  42   b , respectively, of the lock assembly  30 . The hook arms  42   a  and  42   b  include pivot points  44   a  and  44   b  opposite the hook ends  40 , allowing the hook arms  42   a  and  42   b  to swing in a vertical plane aligned with the plane of the strike plate  28  so that the hook ends  40  may engage with the strike engagement notches  38  when the hook ends  40  of the hook arms  42   a  and  42   b  swing toward each clamping the strike plate  28  therebetween and so that the hook ends  40  may disengage with the strike engagement notches  38  when the hook ends  40  of the hook arms  42   a  and  42   b  swing away from each releasing the strike plate  28 . 
   Referring to  FIGS. 2 and 3 , depending on an operating mode of locking or unlocking, the hook ends  40  follow a trajectory  46  or  46 ′, each comprised of two stages of cross-axial motion  48  or  48 ′ and axial motion  50  and  50 ′ in which the hook ends  40  move generally within the plane of the strike plate  28 , either across the separation axis  22  or along the separation axis  22 . 
   When the door  14  is open, the disengaged hook ends  40  first have engaging cross-axial motion  48  in which they pivot toward each other so that the hook ends  40  engage the corresponding notches  38 . The hook ends  40  are then retracted with a generally horizontal inward axial motion  50 , drawing the strike plate  28  attached to the cabinet  12  toward the door  14 . 
   When the door  14  is closed, the direction of these two motions and their order are reversed, with axial motion  50 ′ (being the opposite of axial motion  50 ) allow separation of the strike plate and door  14  and cross-axial motion  48 ′ (being the opposite of cross-axial motion  48 ) allowing the hook ends  40  to be released from their respective notches  38 . 
   Because hook arms  42   a  and  42   b  move in mirror image trajectories reflected about a horizontal axis, the mechanism associated with hook arm  42   a  alone will be described, with the mechanism and operation of hook arm  42   b  simply understood as a mirror image of hook arm  42   a . Referring then to  FIGS. 4   a  and  4   b , hook arm  42  is pivotally attached at pivot point  44   a  to a first end of a swing arm  56  to extend rightward therefrom so that during operation, hook arm  42  may pivot with respect to swing arm  56  about a range of acute angles with hook arm  42   a  above swing arm  56 . 
   The remaining end of swing arm  56  is attached at pivot point  58  to a point on a support plate  57  generally parallel with the strike plate  28 , but fixed with respect to the door  14 . A spring  61  is attached to pivot point  44   a  and to a point fixed with respect to the door  14  so as to bias the swing arm  56  in a clockwise direction throughout a range of angles from about 45 degrees clockwise rotation above horizontal (as shown in  FIG. 4   a ) to horizontal (as shown in  FIG. 4   b ). 
   A drive arm  60   a  is pivotally attached to a pivot point  62  positioned between pivot point  44   a  and hook end  40 , and may move vertically so as to effect the pulling and hooking and pushing and unhooking motions described with respect to  FIGS. 2 and 3 . 
   Referring specifically to  FIG. 4   a , when the door  14  is open, the hook end  40  is at the end of the cross-axial motion  48  prior to engaging notch  38  and drive arm  60   a  is in its full upward position. The downward motion of drive arm  60   a  causes hook arm  42  to swing in a clockwise direction in preference to movement of swing arm  56 , the latter being biased by spring  61 . Motion of hook arm  42  continues until hook end  40  engages the notch  38 . At this point in time, further motion of the hook arm  42  is blocked, and downward motion of drive arm  60   a  is accommodated by rotation of swing arm  56  against the biasing of spring  61 . This rotation of the swing arm  56  draws the hook end  40  in axial motion  50  until it engages with notch  71  and brings the strike plate along with it. 
   Referring to  FIG. 9 , in an alternative embodiment, the drive arm  60   a  may be pivotally attached to the swing arm  56  and an electrical actuator  90 , such as a solenoid, may connect to the swing arm  56  and provide an actuator arm  94 , pivotally attaching to the hook arm  42  to pull the hook arm  42  in the clockwise direction for engagement with the strike plate  28  and to push the hook arm  42  in the counterclockwise direction to disengage the hook arm  42  with the strike plate  28 . The electrical actuator  90  may be driven by a set of contacts (not shown) associated with the gear motor  81  described below. 
   As will be understood from this description, in either embodiment, horizontal motion of the hook end  40  will be a function of a cosine of the angle of swing arm  56  with respect to the separation axis  22  of door  14 . As a result, equal increments of downward motion of drive arm  60  provide decreasing pull-in motion of the hook end  40 , with a concomitant increase in the force of the pull-in, increasing the leverage as the gasket is compressed and increased compression forces are required. 
   It will be further noted that when the lock is fully closed, forces  63  tending to separate the door and cabinet along the separation axis  22  are realized almost entirely in compression along the swing arm  56  rather than torque about pivot point  58 , thus eliminating significant forces on drive arm  60   a  and its actuation mechanism to be described below. 
   Referring specifically to  FIG. 4   b , when the door  14  is closed and locked, the swing arm  56  is substantially horizontal and the hook end  40  is fully engaged in the notch  38  with the drive arm  60   a  at its lowermost position. A raising of the drive arm  60   a  causes swing arm  56  to swing in a clockwise direction in preference to movement of the hook arm  42  under the influence of spring  61 . Motion of swing arm  56  continues until hook end  40  has pushed the strike plate  28  away. At this point in time, further motion of the swing arm  56  is blocked by a stop (not shown), and upward motion of drive arm  60   a  is accommodated by rotation of hook end  40  away from the notch  38 . 
   Referring now to  FIG. 5 , opposite ends of corresponding drive arms  60   a  and  60   b , with respect to the ends connected to their corresponding hook arms  42   a  and  42   b , are attached to a crank  64  rotating about a horizontal shaft  66  generally perpendicular to the plane of the support plate  57  as well as the planes of hook arms  42 , swing arms  56  and drive arm  60   a  and  60   b  and their motion. The crank  64  provides two crank arms separated in angle by 180 degrees: an upper crank arm portion providing a pivot point  68   a  attached pivotally to the lower portion of drive arm  60   a , and a lower crank arm portion providing a pivot point  68   b  attached to the upper end of the lower drive arm  60   b . The crank  64  is rotated to provide the requisite up and down motion of the drive arms  60   a  and  60   b  described above, by a DC gear motor  81 , as will be described further below. 
   Clockwise rotation of the crank  64 , from a position as indicated in  FIG. 5 , with the pivot points  68   a  and  68   b  in vertical opposition, produces sequential cross-axial motion  48  and axial motion  50  (per  FIG. 3 ), as pivot points  68   a  and  68   b  switch positions, with 180 degrees of rotation of the crank  64 . Counterclockwise rotation of the crank  64 , from this position, produces sequential axial motion  50 ′ and cross-axial motion  48 ′, with the crank  64  returning to the position shown in  FIG. 5 . Because the forces on drive arms  60   b  and  60   a  are symmetric, there is no side thrust loading of the shaft of the motor assembly  79  supporting the crank  64 . Further, at the extreme rotations of the crank  64 , corresponding with the door  14  being fully closed against the strike plate  28  or fully open, an axis of force along the drive arms  60   a  and  60   b  is generally aligned with lines between the pivot points  68   a  and  68   b  and the center of the shaft  66  of the gear motor  81 , resulting in a minimized torque on the gear motor  81  from forces on the drive arms  60   a  and  60   b  and a maximum leverage by the gear motor  81  on the drive arms  60   a  and  60   b.    
   Referring now to  FIG. 6 , hook end  40  of hook arm  42   b  (as shown, and similarly for hook arm  42   a ) engages a vertically-extending wall  71  on the door side of notch  38  between a horizontal wall  74  of the notch  38  and an inwardly-projecting tooth  72  so as to capture the hook end  40  between a horizontal wall  74  of the notch  38  and the inwardly-projecting tooth  72 . Similarly, the hook end  40  of the hook arm  42   b  provides a horizontally-extending portion terminating in tooth  70  hooking back toward the door  14  to capture the vertically-extending wall between the body of the hook arm  42  and the tooth  70 . This double hooked-engagement prevents simple bending of the strike plate  28  or the hook arms  42  out of their normal plane of motion from serving to disengage the two, thus resisting jimmying of the locking mechanism  24  by the insertion of a tool to bend these components when the hook bolts are engaged. 
   Referring now to  FIG. 7 , the strike plate  28  may include a guide notch  76  extending horizontally inward from a door facing edge of the strike plate to receive a roller  78  mounted to the support plate  57  generally perpendicular to the plane of the strike plate  28 . Engagement of the guide notch  76  and roller  78  corrects sagging in the door  14  correcting the alignment of the two as the door  14  and cabinet  12  are closed. The roller  78  also resists defeating of the lock by upward or downward displacement of the door to disengage one or both hook arms  42 . 
   A door switch  80  mounted on the support plate  57  may be triggered by a corner of the guide notch  76  to provide an indication that the door  14  and cabinet  12  are sufficiently close as to enable them to be engaged with the locking mechanism  24 . 
   Referring again to  FIGS. 5 and 7 , a hole  91  in the strike plate may align with a threaded hole (not shown) in support plate  57 . A screw  93  passing through the support plate  57  into hole  91  provides for a shipping lock for the assembly. 
   A cover  100  may fit over the lock assembly  30  to protect the motor assembly  79  and other components from tampering or damage. 
   Referring now to  FIG. 8 , the motor assembly  79  attached to the crank  64  to rotate it about axis  66  includes a DC gear motor  81  that also rotates a cam  82  turning equally with the crank  64 . The cam  82  actuates a pair of single-pole, double-throw switches  84   a  and  84   b  as will be described. 
   Motor assembly  79  also incorporates a relay  87  that may control the locking and unlocking of the door through two, tandem single-pole, double-throw contact sets  86   a  and  86   b . The relay coil  88  may be energized by a radio receiver  90 , such as a Bluetooth receiver, receiving an encrypted signal to control locking or unlocking of the door. Alternatively, or in addition, the relay coil  88  may be activated by a key switch (not shown) allowing manual switching with a key or the like. In yet another embodiment, the key switch may replace the relay  87 . 
   The poles of the double-pole switches  84  are connected to opposite terminals of the DC motor  81  that drives the cam  82  and the crank  64 . Generally, the cam  82  and switches  84   a  and  84   b  serve to stop the rotation of the crank  64  in either of the two positions separated by 180 degrees as described above with pivot points  68   a  and  68   b  are vertically opposed. 
   When the relay  87  is in a lock position, contact set  86   a  connects one terminal of the motor  81  to ground (through its “lock” throw) while contact set  86   b  connects the other terminal of the motor  81  to the pole of switch  84   b  (also through its “lock” throw). When the door  14  is closed and locked, switch  84   b  is connected to its “lock limit” throw, which is in turn also connected to ground. Thus, both terminals of the motor  81  are grounded and there is no motion of the motor  81 . 
   When contact set  86   a  is moved to the unlocked position, with the door  14  still in the locked state, the corresponding terminal of the motor  81  is connected to an “unlock” throw of contact set  86   a , which leads to the pole of switch  84  (in “normally open” throw), which connects through closed door switch  80  to a source of power. The remaining terminal of motor  81  is connected through contact set  86   b , which now connects to this terminal to ground through its “unlock” throw. These connections cause gear motor  81  to turn in an unlocking direction (counterclockwise per  FIG. 5 ). 
   The motor  81  turns until cam  82  reverses the pole positions of switches  84   a  and  84   b . This in turn causes a grounding of the unlock throw of contact set  86   a , providing ground to both terminals of gear motor  81 , causing the motor  81  to stop. The grounding of both terminals of the gear motor  81  provides a dynamic braking of the motor in which kinetic energy of the gear motor  81  is absorbed by resistive dissipation of power generated by the gear motor  81 , reducing any coasting of the gear motor  81 . 
   Door switch  80 , at this time, may open as the door  14  is opened preventing further actuation of the motor  81  until the door  14  is again closed sufficiently to close the door switch  80  (generally before substantial compression of the gasket). 
   When the door  14  is closed, a change of state of the contact set  86 , for example, by activation of the relay  87 , moves the pole of contact set  86  back to the “lock” throw state connecting one terminal of gear motor  81  to ground and the second terminal of the motor  81  through contact set  86   b  and its “lock” throw, to switch  84   b  (now in the opposite state shown in  FIG. 8 ). Switch  84  completes a connection between the terminal of the gear motor  81  to power via the door switch  80 . 
   Assuming that the door  14  is sufficiently closed so that the locking mechanism  24  can operate, power is again provided to the motor  81 , but this time in the opposite polarity as before, rotating the cam  82  to lock the door  14  until it returns to the state shown in  FIG. 8  with switch  84   b  connecting the terminal of motor  81  attached to contact set  86   b  to ground, and switch  84   a  connecting the terminal of motor  81  attached to contact set  86   a  to ground. Motion of the motor  81  is again stopped with dynamic braking. 
   It will be understood from the above description that the relative position of the strike plate  28  and the lock assembly  30  on the door  14  and cabinet  12  may be reversed. 
     FIG. 10  shows a version of the present invention having only one hook bolt and associated mechanism. 
   It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.