Abstract:
A latch including a housing, a rotary pawl, catch means for releasably holding the pawl in a closed configuration, and means for operating the catch means are disclosed.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of U.S. provisional application for patent No. 61/035,370, filed on Mar. 10, 2008, which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of Invention 
         [0003]    The present invention relates to the field of latch assemblies. 
         [0004]    2. Brief Description of the Related Art 
         [0005]    Latch assemblies are relied on in many applications for securing items, such as panels, doors, and doorframes together. For example, containers, cabinets, closets, drawers, compartments and the like may be secured with a latch. Furthermore, in many applications an electrically operated latch is desirable due to the need for remote or push-button entry, coded access, key-less access, or monitoring of access. Various latches for panel closures have been employed where one of the panels such as a swinging door, drawer or the like is to be fastened or secured to a stationary panel, doorframe, cabinet, or compartment body. Although many latch assemblies are known in the prior art, none are seen to teach or suggest the unique features of the present invention or to achieve the advantages of the present invention. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention is directed to a latching system for securing two members together. The present invention includes a housing, a rotary pawl, catch means for releasably holding the pawl in a closed position, and actuation means for selectively moving the catch means out of engagement with the pawl. The pawl is pivotally attached to the housing and is rotationally movable between a closed or engaged position and an open or disengaged position. The pawl is provided with a torsion spring member that biases the pawl toward the open or disengaged position. The catch means includes a catch member that is pivotally movable between an engaged position and a disengaged position and is spring biased toward the engaged position. The catch member can be disengaged, in other words moved to the disengaged position, by the action of the actuation means, which in the illustrated example is a motorized plunger. When the pawl strikes a keeper during closing, the pawl is moved to the closed position. An elongated arm projecting from the main body of the pawl is engaged by the catch member once the pawl is in the closed position in order to keep the pawl in the closed position. At this time the pawl captures the keeper to secure the latch to the keeper. The actuation means includes a motor, a reduction gear system, a rotary cam, and a plunger. Energizing the motor pushes the catch member to the disengaged position, which allows the pawl to rotate under the force of the torsion spring to the open position. Thus, the latch can be disengaged from the keeper and a door or drawer, for example, can be opened. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0007]      FIG. 1  is an environmental view of an embodiment of a latch assembly according to the present invention shown in the latched configuration. 
           [0008]      FIG. 2  is another environmental view of the latch assembly of  FIG. 1  shown in the latched configuration. 
           [0009]      FIG. 3  is an environmental view of the latch assembly of  FIG. 1  shown in the unlatched configuration. 
           [0010]      FIG. 4  is another environmental view of the latch assembly of  FIG. 1  shown in the unlatched configuration. 
           [0011]      FIGS. 5-15  are views of the latch assembly of  FIG. 1  shown in the latched configuration. 
           [0012]      FIGS. 16-24  are views of the latch assembly of  FIG. 1  shown in the latched configuration. 
           [0013]      FIG. 25  is a cross sectional view of the latch assembly of  FIG. 1  showing the latch in the unlatched configuration with the trigger or catch actuated by cable. 
           [0014]      FIG. 26  is a cross sectional view of the latch assembly of  FIG. 1  showing the latch in the unlatched configuration with the trigger or catch actuated by the motorized plunger. 
           [0015]      FIG. 27  is an exploded view of the latch assembly of  FIG. 1 . 
           [0016]      FIGS. 28-29  are views of the cover plate of the housing of the latch assembly of  FIG. 1 . 
           [0017]      FIGS. 30-34  are views of the base plate of the housing of the latch assembly of  FIG. 1 . 
           [0018]      FIGS. 35-39  are views of the rotary pawl of the latch assembly of  FIG. 1 . 
           [0019]      FIGS. 40-44  are views of the pawl spring of the latch assembly of  FIG. 1 . 
           [0020]      FIGS. 45-48  are views of a pivot shaft of the type used to pivotally support the pawl and the catch of the latch assembly of  FIG. 1 . 
           [0021]      FIGS. 49-50  are views of a spacer bar used to keep the proper distance between the plates of the housing of the latch assembly of  FIG. 1 . 
           [0022]      FIGS. 51-57  are views of the catch or trigger of the latch assembly of  FIG. 1 . 
           [0023]      FIGS. 58-61  are views of the catch or trigger spring of the latch assembly of  FIG. 1 . 
           [0024]      FIG. 62  is an exploded view of the motorized drive mechanism of the latch assembly of  FIG. 1 . 
           [0025]      FIGS. 63-67  are views of the motorized drive mechanism of the latch assembly of  FIG. 1 , shown with the plunger retracted. 
           [0026]      FIGS. 68-72  are views of the motorized drive mechanism of the latch assembly of  FIG. 1 , shown with the plunger extended. 
           [0027]      FIG. 73  is a diagrammatic view of the circuit board that controls the motorized drive mechanism of the latch assembly of  FIG. 1 . 
           [0028]      FIGS. 74-80  are views of the cam of the motorized drive mechanism of the latch assembly of  FIG. 1 . 
           [0029]      FIGS. 81-87  are views of the plunger of the motorized drive mechanism of the latch assembly of  FIG. 1 . 
           [0030]      FIGS. 88-89  are views of the first half of the housing of the motorized drive mechanism of the latch assembly of  FIG. 1 . 
           [0031]      FIGS. 90-96  are views of the motor and gearbox of the motorized drive mechanism of the latch assembly of  FIG. 1 . 
           [0032]      FIGS. 97-98  are views of the second half of the housing of the motorized drive mechanism of the latch assembly of  FIG. 1 . 
           [0033]      FIGS. 99-103  are views of a micro-switch that signals that the latch assembly is in the open configuration used in the latch assembly of  FIG. 1 . 
           [0034]      FIG. 104  is an exploded view of an alternative motorized drive mechanism for use with the latch assembly of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0035]    Referring to  FIGS. 1-104 , a latch  400  in accordance with the present invention can be seen. The latch  400  includes a latch housing  402 , a pawl  404 , a catch or trigger  406 , and actuation means for selectively moving the catch or trigger out of engagement with the pawl. In the illustrated embodiment, an electrically operated actuator assembly  408  serves as the actuation means for selectively moving the trigger out of engagement with the pawl. 
         [0036]    The latch  400  is generally applicable wherever one or more closure members need to be secured in a certain position. The latch  400  can be used together with the striker  508  to secure any two closure members together. In the illustrated example, the latch  400  is shown being used for securing a drawer  500  relative to a cabinet  509  (only the portion of the cabinet supporting the drawer and the latch  400  is shown). Further, the latch  500  can be mounted to either the movable member or the stationary member. In addition, the latch  400  may be mounted in any orientation depending upon the particular application. 
         [0037]    In the illustrated embodiment, the housing  402  is formed by a first plate  403  and a second plate  401  that receive the various components of latch  400  between them. In the illustrated embodiment, the second plate of the housing  402  acts as a cover plate  401 , and the second plate of the housing  402  acts as a base plate  403 . Furthermore, the housing must be adapted to allow an unobstructed path to the pawl slot  458  when the pawl  404  is in the open position. The housing  402  has an opening  415  that allows at least a portion of the striker  508  to enter the housing  402  for engagement by the pawl  404 . In the illustrated example, the opening  416  is formed by slots  412 ,  413  provided in registry with each other in the cover plate  401  and the base plate  403  of the housing, respectively. The slots  412 ,  413  form an open, approximately U-shaped indentation or recess in the housing  402  as viewed in profile. The slots  412 ,  413  allow at least a portion of the striker  508  to enter the housing  402  for engagement and capture by the pawl  404 . The slots  412 ,  413  allow an unobstructed path to the pawl slot  458  when the pawl  404  is in the open position. The slots  412 ,  413  are sized such that the housing  402  will not interfere with the movement of the striker  508  relative to the housing  402  as the pawl  404  is moved from the open position to the closed position by contact with the striker  508 . 
         [0038]    The electrically operated actuator assembly  408  includes a motor  410 , a reduction gear system  414 , a cam  416 , and a plunger  418 . In the illustrated embodiment, the output shaft of the motor  410  is engaged to the reduction gear system  414  such that it provides a motive force or an input torque to the reduction gear system  414  when the motor is energized. The motive force or input torque provided by the motor is rotational and imparts rotation to the gear wheels (not shown) of the reduction gear system  414 . The operation of a reduction gear system and the interconnection between a reduction gear system and a motor output shaft are well known and therefore are not discussed in detail. Accordingly, the output shaft of the motor rotates in response to the motor being energized and in turn causes the output shaft  420  of the reduction gear system  414  to rotate. By a reduction gear system it is meant that the output shaft of the motor must rotate several times or more for each rotation of the output shaft  420  of the reduction gear system  414 . This arrangement reduces the torque output and consequently the size of the motor  410  required for the proper operation of the latch  400 . The motor  410 , the reduction gear system  414 , the cam  416 , and the plunger  418  are received in their own housing  421 , which in turn is installed in the latch housing  402 . The cam  416  is attached to the output shaft  420  of the reduction gear system  414 . The cam  416  has a pair of ramps  424  that each extend along a spiral path for approximately 180° or less about a central shaft  422  of the cam  416 . The ramps  424  both rise in the same direction of rotation. The cam  416  also has a receptacle  423  that receives the output shaft  420  of the reduction gear system  414  in a manner such that the cam  416  rotates with the output shaft  420  as a unit during normal operation of the latch  400 . For example, the receptacle  423  and the output shaft  420  may have mating non-circular cross sections such that no relative rotation can occur between the receptacle  423  and the output shaft  420  and thus between the cam  416  and the output shaft  420 . 
         [0039]    The plunger  418  includes a pair of ramps  426  that are substantially like the ramps  424 . The ramps  426  are received between the ramps  424  when the plunger  418  is in the retracted position such that the apex  425  of each ramp  426  seats against the bottom  427  of each ramp  424 . The plunger  418  has a receptacle  429  that telescopically receives the central shaft  422  of the cam  416  to help guide the rectilinear motion of the plunger  418  between its extended and retracted positions. The plunger  418  has a plunger shaft portion  540  that has a non-circular cross section and is received at least in part within the mating non-circular opening  542  of the actuator housing  421 . This arrangement prevents relative rotation between the plunger  418  and the actuator housing  421 , while allowing the plunger  418  to move rectilinearly between its retracted position and its extended position where it projects out of the actuator housing  421 . Non-circular as used herein includes any shape other than a perfect circle and includes a circle interrupted by a groove or a flat planar surface. In the illustrated example, the opening  542  and the plunger shaft  540  are rectangular in cross section. 
         [0040]    The central longitudinal axes of the cam  416 , the plunger  418  and the motor  410  are coincident in the illustrated embodiment. The axis of rotation of the pawl  404  is offset to one side of the longitudinal axes of the cam  416 , the plunger  418  and the motor  410 . 
         [0041]    When the motor  410  is energized, the cam  416  rotates causing the ramps  426  to ride up the ramps  424 , given that the plunger  418  cannot rotate, such that the plunger  418  will move from its retracted position toward its extended position until the apex of each ramp  426  reaches the apex  544  of each ramp  424  where the plunger  418  reaches its extended position and pushes the catch  406  to release the pawl  404  from its closed position. Further rotation of the cam  416  brings the bottoms  427  of the ramps  424  into registry with the apexes  425  of the ramps  426  and the plunger  418  is free to move back to its retracted position. At this point the control circuitry on the circuit board  546  shuts off power to the motor  410  stopping further rotation of the cam  416 . The catch  406 , due to the bias of the catch spring  488 , pushes the plunger  418  back to its retracted position and the latch  400  is again ready to repeat its operating cycle. 
         [0042]    The latch assembly  400  also includes a pawl  404  shown pivotally connected to the latch housing  402  with suitable attachment means such as the pawl pivot pin  438  that passes through the hole  440  in the pawl  404 . The cover plate  401  and the base plate  403  of the housing  402  are each provided with a hole  432  and  433  for receiving the ends of the pivot pin  438  as the plates  401  and  403  are assembled together. Thus, the pawl  404  is rotationally supported by the housing  402 . 
         [0043]    The pawl  404  has an elongated arm  454  provided for engagement by the trigger  406 . The trigger  406  has a catch surface  548  that can catch the tip of the arm  454  and hold the pawl  404  in its closed position. The long arm  454  reduces the frictional force between the catch  406  and the pawl  404  due to the reaction force caused by the torque imparted to the pawl by the pawl torsion spring  462 . This in turn reduces the torque and power output required of the motor  410 , which allows further reductions in motor and latch size and ultimate latch cost. 
         [0044]    The pawl  404  is provided with a pawl slot  458  to retain the striker  508  when the pawl  404  is in the latched or closed position. In the illustrated example, the striker  508  has a rod-shaped portion  434  that engages the pawl slot  458  as the panel  500  is moved to the closed position relative to the compartment  509 . When the panel  500  is closed, the rod-shaped portion  434  of the striker  508  will be positioned or caught in the pawl slot  458  with the pawl  404  in the latched position. 
         [0045]    A pawl torsion spring  462  is installed in the housing  402  with the coiled portion  464  of the torsion spring  462  surrounding the pivot pin  438 . An arm  468  of the torsion spring  462  engages a hole  460  in the pawl  404 . The torsion spring  462  also has a second arm  472  that engages the housing  402 . 
         [0046]    With the arm  472  of the torsion spring  462  in engagement with the wall  466  of the housing  402 , the arm  468  of the torsion spring  462  exerts a force on the pawl  404  that biases the pawl  404  toward the open or unlatched position. 
         [0047]    The trigger  406  is in the form of an elongated lever that is pivotally supported in the housing  402  near one of its ends. The pivot axis of the trigger  406 , as defined by the trigger pivot pin  470 , is parallel to the pivot axis or axis of rotation of the pawl  404 . Furthermore, the pivot axis of the trigger  406 , as defined by the trigger pivot pin  470 , is spaced apart from the pivot axis or axis of rotation of the pawl  404 . The trigger  406  is pivotally movable between an engaged position and a disengaged position and is spring biased toward the engaged position. A trigger spring  488  is provided for biasing the trigger  406  toward the engaged position. The trigger spring  488  is a torsion spring and has a coiled portion  474 , a first arm  476 , and a second arm  478 . The trigger spring  488  is installed in the housing  402  with the coiled portion  474  of the torsion spring  488  surrounding the trigger pivot pin  470 . The arm  476  of the torsion spring  488  engages the hole  482  in the trigger  406 . The second arm  478  of the torsion spring  488  engages the housing  402 . 
         [0048]    The trigger  406  engages the pawl arm  454  at a point intermediate its pivot axis and the location on the trigger  406  where the plunger  418  contacts the trigger  406 . This arrangement provides a mechanical advantage to the plunger  418  due to the long lever arm afforded by the trigger  406 . Once again, this arrangement reduces the torque and power output required of the motor  410 , which allows further reductions in motor and latch size and ultimate latch cost. 
         [0049]    The trigger pivot pin  470  passes through a hole in the trigger  406  near one end of the trigger  406 . The trigger  406  engages the arm  454  to hold the pawl  404  in the latched position when the trigger  406  is in the engaged position. As the plunger  418  moves from the retracted to the extended position, the plunger  418  engages the trigger  406  to pivotally move the trigger  406  to the disengaged position where the trigger  406  no longer engages the pawl  404 . When the trigger  406  is in the disengaged position, the pawl  404  is free to rotate under spring bias to the unlatched position. The rod-shaped portion of the striker  508  can now be withdrawn from the pawl slot  458  and the drawer  500  can be moved to the open position. 
         [0050]    The trigger spring  488  biases the trigger  406  toward the engaged position where the trigger  406  will tend to reengage the pawl  404  if the pawl  404  is rotated to the latched position. If the drawer  500  is again moved to the closed position relative to the cabinet  509 , the rod-shaped portion of the striker  508  will impact the pawl slot  458  and cause the rotation of the pawl  404  to the latched position. Once the pawl  404  is in the latched position, the pawl can again be engaged by the trigger  406  to thereby retain the pawl in the latched position and secure the drawer  500  in the closed position. 
         [0051]    The latch assembly  400  is actuated by energizing the motor  410 . The motor  410  may be energized using a remotely located switch (not shown). The plunger  418  is normally in the retracted position when the drawer  500  is secured in the closed position. When the motor  410  is energized, the cam  416  is rotated causing the plunger  418  to be rectilinearly displaced to the extended position. As the plunger  418  moves to the extended position, the plunger impacts the trigger  406  and causes the trigger  406  to move to the disengaged position thereby freeing up the pawl  404  for pivoting. The bias provided by the pawl torsion spring  462  rotates the pawl  404  from its latched or closed position, illustrated in  FIG. 9 , where the rod-shaped portion  434  of the striker  508  is captured by the pawl slot  458 , toward its unlatched position illustrated in  FIG. 26 . The rotation of the pawl  404  moves the opening of the pawl slot  458  such that the opening of the pawl slot  458  substantially registers with the slots  412 ,  413  of the housing  402 , thus allowing the striker  508  to be disengaged from the pawl  404 . The drawer  500  can then be opened by moving it to the open position. 
         [0052]    The latch assembly  400  can be mounted on a panel or mounting surface, such as the frame surrounding the opening of the compartment  509 , using a variety of well-known fasteners. In this example, the hollow pivot pins of the pawl  404  and of the trigger  406  allow bolts  550 ,  552  that are fixed to the cabinet to pass through the latch  400 . Then nuts (not shown) can be engaged to the bolts  550 ,  552  to secure the latch  400  to the cabinet. In the illustrative example, the striker  508  is mounted to the drawer  500  such that, as the drawer  500  is closed, the rod-shaped portion  434  of the striker  508  passes through the slots  412 ,  413  to engage the pawl slot  458 . 
         [0053]    The control circuit  546  would be programmed to supply electrical current to the motor  410  for a predetermined period of time corresponding to approximately a 180° rotation of the cam  416 . Alternatively, the duration of the energizing of the motor can be controlled through feedback. In this alternative, the cam  416  can be painted black on one side and white on the other; each color extending over approximately a 180° of the outer circumference of the cam  416 . An optical sensor provided on the circuit board  546  would then detect the color boundary between the light and dark areas and generate a signal to shut off electricity to the motor  410 . 
         [0054]    The circuit board  546  is interfaced to the remote switch and power supply by three wires  554 ,  556 ,  558 . The circuit board  546   a  has a two-wire interface using wires  554   a  and  556   a.  The choice would depend on the ultimate application for which the end user intends to use the latch  400 . Also a circuit board having both types of interface can be provided for the latch  400 . 
         [0055]    The latch  400  may also include a micro switch  532  tripped by the pin  560  to provide a “door ajar” signal to a remote control panel. 
         [0056]    As a mechanical backup the trigger  406  can be moved to the disengaged position by the cable  562 . 
         [0057]    It will be apparent to those skilled in the art that various modifications can be made to the latch of the present invention without departing from the scope and spirit of the invention, and it is intended that the present invention cover modifications and variations of the latch which are within the scope of the appended claims and their equivalents.