Patent Abstract:
The present invention is directed to improvements in latch design. The illustrated embodiment of the present invention is a rotary pawl latch with the capability to provide a compressive force between the first member and the second member.

Full Description:
[0001]    This application claims the benefit of the priority of U.S. Provisional Application for Patent Ser. No. 60/866,604, filed on Nov. 20, 2006, the entirety of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a latch for releasably securing a first member, such as a door, panel or the like, relative to a second member. 
         [0004]    2. Description of the Prior Art 
         [0005]    Latches are used to releasably secure panels, covers, doors, electronic modules, and the like to other structures such as compartments, cabinets, containers, doorframes, other panels, frames, racks, etc. Although many latch designs are known in the art, none offers the advantages of the present invention. The advantages of the present invention will be apparent from the attached detailed description and drawings. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention is directed to improvements in latch design. The illustrated embodiment of the present invention is a rotary pawl latch with the capability to provide a compressive force between the first member and the second member. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIGS. 1-117  illustrate an exemplary embodiment of a latch according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0008]    Referring to  FIGS. 1-117 , a latch  200  in accordance with an exemplary embodiment of the present invention can be seen. The latch  200  includes a latch housing  202 , a pawl  204 , a trigger or catch  206 , and actuation means for selectively moving the trigger  206  out of engagement with the pawl  204  and retracting the pawl toward the interior of the housing  202 . In the illustrated embodiment, an electrically operated actuator assembly  208  serves as the actuation means for selectively moving the trigger  206  out of engagement with the pawl  204  and retracting the pawl toward the interior of the housing  202 . 
         [0009]    The latch  200  is generally applicable wherever one or more closure members need to be secured in a certain position. The latch  200  can be used together with the striker  308  to secure any two closure members together. In the illustrated example, the latch  200  is shown being used for securing a trunk lid  300  relative to the trunk of a vehicle (not shown). In use, the latch  200  can be secured to the interior of the vehicle trunk, such that it can be engaged by the striker  308 , using any well known means such as, for example, screws or the like. 
         [0010]    Preferably, the housing  202  is of the clam-shell type having a first portion  211  and a second portion  213  so as to allow the housing  202  to receive the various components of the latch  200 . Furthermore, the housing must be adapted to allow an unobstructed path to the pawl slot  258  for the striker  308  when the pawl  204  is in the open configuration relative to the support plate  215 . The housing  202  has an opening that allows at least a portion of the striker  308  to enter the housing  202  for engagement by the pawl  204 . In the illustrated example, the opening is in the form of a slot  212  that passes through the first portion  211  of the housing  202 . The slot  212  forms an open, approximately U-shaped cut-out in the housing  202  as viewed in profile. The slot  212  allows at least a portion of the striker  308  to enter the housing  202  for engagement by the pawl  204 . The slot  212  allows an unobstructed path to the pawl slot  258  when the pawl  204  is in the open configuration relative to the support plate  215 . The slot  212  is sized such that the housing  202  will not interfere with the movement of the striker  308  relative to the housing  202  as the pawl  204  is moved from the open configuration to the closed configuration relative to the support plate  215  by contact with the striker  308  and as the pawl  204  is retracted toward the interior of the housing  202  by the electrically operated actuator assembly  208 . 
         [0011]    The electrically operated actuator assembly  208  includes a motor  210 , a worm gear  214  that is in the form of an Archimedes or helical screw, a pinion gear  216 , a cam gear  218  and the support plate  215 . The motor  210  has an output shaft  220  that normally rotates in response to the motor being energized. Reversing the polarity of the current supplied to the motor  210  causes the direction of rotation of the output shaft  220  to be reversed. The motor  210  is received in the housing  202  and is installed at a fixed location therein. The worm gear  214  is diagrammatically represented in the attached drawings. The worm gear  214  is attached to the output shaft  220  of the motor  210  such that the worm gear  214  rotates with the shaft  220  as a unit during normal operation of the latch  200 . 
         [0012]    The pinion gear  216  includes two adjacent coaxial gear wheels  229 ,  227  that rotate as a unit about a common axis of rotation. The first gear wheel  229  is of a larger diameter as compared to the second gear wheel  227 . In the illustrated example, the pinion gear  216 , including the gear wheels  229 ,  227 , is of one-piece construction. The pinion gear  216  also includes two axially projecting pivot pins  223 ,  225  for rotationally supporting the pinion gear  216  in the housing  202 . The worm gear  214  is in mesh with the pinion gear  216 . In the illustrated example, the helical screw of the worm gear  214  engages the gear teeth (not shown) of the gear wheel  229 , such that the worm gear  214  is in mesh with a first portion of the pinion gear  216 . Accordingly, rotation of the worm gear  214  causes rotation of the pinion gear  216  when the motor  210  is energized. 
         [0013]    The cam gear  218  includes a gear wheel  222 , a proximal cam  203 , and a distal cam  205 . The proximal cam  203  is adjacent the gear wheel  222 . The distal cam  205  is adjacent the proximal cam  203 , with the proximal cam  203  being intermediate the gear wheel  222  and the distal cam  205 . The gear wheel  222 , the proximal cam  203 , and the distal cam  205  rotate as a unit about a common axis of rotation. The gear wheel  222  of the cam gear  218  has a plurality of gear teeth (not shown) evenly distributed about its circumference. The proximal cam  203  has an arc-shaped cam lobe  207 , located at a distance from the axis of rotation of the cam gear  218 , for tripping the catch or trigger  206 . The distal cam  205  is substantially in the shape of a right circular cylinder supported eccentrically relative to the axis of rotation of the cam gear  218 . In the illustrated example, the cam gear  218 , including the gear wheel  222 , the proximal cam  203 , and the distal cam  205 , is of one-piece construction. The cam gear  218  is rotationally supported in the housing  202  by the cam gear pin  209 . The cam gear pin  209  is held in place by the cam gear screw  217 . The cam gear  218  is in mesh with the pinion gear  216 . In the illustrated example, the teeth (not shown) of gear wheel  222  of the cam gear  218  engage the gear teeth (not shown) of the gear wheel  227 , such that the cam gear  218  is in mesh with a second portion of the pinion gear  216 . Accordingly, rotation of the pinion gear  216  causes rotation of the cam gear  218  when the motor  210  is energized. 
         [0014]    The support plate  215  is supported for rectilinear translation by the housing  202 . The support plate  215  rotationally supports the pawl  204 . The support plate  215  pivotally supports the trigger  206 . The support plate  215  has a cut-out  224  proximate the pawl  204  such that the support plate  215  will not interfere with the movement of the striker  308  relative to the support plate  215  as the pawl  204  is moved from the open configuration to the closed configuration relative to the support plate  215  by contact with the striker  308 . The support plate  215  has an elongated slot  226  that is engaged by the distal cam  205  of the cam gear  218 , such that rotation of the cam gear  218  causes reciprocating, rectilinear movement of the support plate  215  relative to the housing  202 . The elongated slot  226  has a width that is approximately equal to the diameter of the distal cam  205 , while the length of the elongated slot  226  is greater than the sum of the diameter of the distal cam  205  and twice the distance between the central axis of the distal cam  205  and the axis of rotation of the cam gear  218 . 
         [0015]    As previously stated the latch assembly  200  includes a pawl  204  shown pivotally or rotationally connected to the support plate  215  with suitable attachment means such as the pawl pivot pin  238  that passes through the hole  240  in the pawl  204 . The support plate  215  is provided with a hole  232  for receiving one end of the pivot pin  238 . Thus, the pawl  204  is rotationally supported by the support plate  215 . 
         [0016]    The pawl  204  has first and second teeth  254 ,  233  provided for engagement by the trigger  206 . The pawl  204  is provided with a pawl slot  258  to capture and hold the striker  308  when the pawl  204  is in either one of a first latched position (shown in FIGS.  4  and  12 - 18 ) and a second latched position (shown in  FIGS. 28 and 29 ) relative to the support plate  215 . In the illustrated example, the striker  308  has a rod-shaped portion  234  that engages the pawl slot  258  as the trunk lid  300  is moved to the closed position relative to the vehicle&#39;s trunk (not shown) and consequently relative to the latch  200 . 
         [0017]    During normal operation, assuming the latch  200  is initially in the normal unlatched configuration shown in  FIGS. 1 ,  2 ,  5 ,  6 ,  7 , and  11 , when the trunk lid  300  is closed, the rod-shaped portion  234  of the striker  308  will be positioned or caught in the pawl slot  258  with the pawl  204  being moved to the first latched position relative to the support plate  215 . 
         [0018]    A pawl torsion spring  262  is installed on the support plate  215  with the coiled portion  264  of the torsion spring  262  surrounding the pivot pin  238 . An arm  268  of the torsion spring  262  engages the notch  260  in the pawl  204 . The torsion spring  262  also has a second arm  272  that engages the support plate  215 . 
         [0019]    With the arm  272  of the torsion spring  262  in engagement with the support plate  215 , the arm  268  of the torsion spring  262  exerts a force on the pawl  204  that biases the pawl  204  toward the open or unlatched position relative to the support plate  215 . 
         [0020]    The trigger  206  is pivotally supported on the support plate  215 . The pivot axis of the trigger  206 , as defined by the trigger pivot pin  270 , is parallel to the pivot axis or axis of rotation of the pawl  204 . Furthermore, the pivot axis of the trigger  206 , as defined by the trigger pivot pin  270 , is spaced apart from the pivot axis or axis of rotation of the pawl  204 . The trigger  206  is pivotally movable between any one of a first engaged position (shown in  FIGS. 12-18 ) and a second engaged position (shown in  FIGS. 28 and 29 ) and a disengaged position (shown in  FIGS. 19 ,  20 ,  30 , and  31 ) and is spring biased toward the first and second engaged positions. In the illustrated embodiment, the first and second engaged positions of the trigger  206  may be coincident, but they need not be so. A trigger spring  288  is provided for biasing the trigger  206  toward the first and second engaged positions. The trigger spring  288  is a torsion spring and has a coiled portion  274 , a first arm  276 , and a second arm  278 . The trigger spring  288  is installed on the support plate  215  with the coiled portion  274  of the torsion spring  288  surrounding the trigger pivot pin  270 . The arm  276  of the torsion spring  288  engages the step or notch  282  in the trigger  206 . The second arm  278  of the torsion spring  288  engages the support plate  215 . 
         [0021]    The trigger  206  has a first lever arm  284  and a second lever arm  286  that extend approximately along the same arc on either side of the pivot axis of the trigger  206  as defined by the trigger pivot pin  270 . The trigger pivot pin  470  passes through a hole in the trigger  206 . The trigger  206  has a notch  290  that receives and engages the first tooth  254  of the pawl  204  to hold or retain the pawl  204  in the first latched position relative to the support plate  215 . Also, the notch  290  of the trigger  206  receives and engages the second tooth  233  of the pawl  204  to hold or retain the pawl  204  in the second latched position relative to the support plate  215 . 
         [0022]    The operation of the latch  200  will now be explained. With the latch initially in the fully unlatched configuration of  FIGS. 1 ,  2 ,  5 - 7 , and  11 , as the trunk lid  300  is moved to the closed position, the rod-shaped portion  234  of the striker  308  will be positioned or caught in the pawl slot  258  with the pawl  204  being moved to the first latched position relative to the support plate  215  as a result of the contact of the striker  308  with the pawl  204 . The pawl  204  is now in the first latched position relative to the support plate  215  as illustrated in  FIGS. 12-14 . The trigger  206  is in its first engaged position relative to the support plate  215  and retains the pawl  204  in its first latched position. The cam lobe  207  of the cam gear  218  is in its initial position shown in  FIGS. 12 and 14  where it does not contact the trigger  206 . As shown in  FIG. 13 , when the pawl  204  reaches the first latched position a pin  219  carried by the pawl and projecting through the arc-shaped slot  221  in the support plate  215  trips a microswitch  332  that is mounted on the side of the support plate  215  opposite the pawl  204 . Once the microswitch  332  is tripped a signal is generated to an electronic control circuit (not shown) that controls the current supplied to the motor  210 , and in response the control circuit causes the supply of electrical current to the motor  210  with a first polarity to cause the rotation of the cam gear  218  to the position illustrated in  FIGS. 15 and 16 . This is the fully latched configuration of the latch  200  and the cam lobe  207  of the cam gear  218  is in its fully latched position relative to the housing  202 . As the cam gear  218  rotates from its initial position to its fully latched position, the cam lobe  207  does not contact the trigger  206 . As the cam gear  218  rotates from its initial position to its fully latched position, the distal cam  205  causes the support plate to move rectilinearly to the retracted position shown in  FIGS. 15 and 16 , corresponding to the fully latched configuration of the latch  200 . During the rectilinear movement of the support plate  215  to the retracted position, the support plate  215  rectilinearly translates about 5.5 mm inward relative to the housing  202 . This movement of the support plate  215  pulls the striker  308  about 4.5 mm toward the interior of the latch  200 . In use, this would compress a sealing gasket (not shown) provided around the edge of the trunk lid  300  with a compressive force of up to 800 N. 
         [0023]    In the fully latched position a second microswitch  231  of the double switch type, supported by the housing  202 , senses that the latch is in the fully latched position and signals the control circuit to shut off the supply of electrical current to the motor  210 . The latch is now fully latched. The microswitch  231  can sense when the cam gear  218  is in the position corresponding to the fully latched position of the latch and when the cam gear  218  is in the position corresponding to the unlatched position of the latch. This can, for example, be accomplished by two projections (not shown) that are 180° apart and are provided on the side of the gear wheel  222  opposite the cam lobe  207 . These projections would trip the microswitch  231  in either position of the cam gear  218 . Alternatively, two microswitches can be provided in the housing  202  that are 180° apart and that are tripped by a single projection on the gear wheel  222 . These are examples of the many configurations for detecting the position of a gear wheel that are well known in the art and can be used in the present invention. The present design can withstand a force of up to 12,000 N without breaking. 
         [0024]    If normal closing is blocked, for example by items in the trunk, after a predetermined time without a signal from the microswitch  231 , the control circuit reverses the current to the motor to trip the trigger  206  by the reverse movement of the cam lobe  207  and the trunk lid  300  is released and the latch  200  is returned to the initial fully unlatched configuration. 
         [0025]    To open the latch  200  the motor  210  is energized by the user using a remotely located switch (not shown). The cam gear  218  rotates from the fully latched position of  FIGS. 15 and 16  to bring the cam lobe  207  into contact with the first lever arm  284  of the trigger  206  as shown in  FIGS. 17 and 18 . The rotation of the cam gear  218  to its trigger release position trips the trigger  206  to release the pawl  204  as shown in  FIGS. 19 and 20 . The striker  308  is now released and the trunk lid  300  can be opened. The motor  210  remains energized until the cam gear  218  is once again in its fully unlatched position and the support plate  215  is return to its extended position as illustrated in  FIGS. 1 ,  2 ,  5 - 7 , and  11 . The microswitch  231  senses that the latch  200  is in the fully unlatched position and signals the control circuit to stop energizing the motor. 
         [0026]    Referring to  FIGS. 22-27 , if the motor  210  or associated circuitry fail with the latch fully latched and the trunk lid  300  closed, the Bowden cable  350  provides a back-up mechanical release mechanism that will be operated by a lever (not shown) from the interior of the vehicle. The Bowden cable  350  is engaged to a sliding block  352  that is supported for rectilinear movement by the housing  202 . When the Bowden cable is pulled the sliding block  352  engages the second lever arm  286  to trip the trigger  206  and release the pawl  204  and consequently the striker  308 , and the trunk lid can then be opened. A spring  354  returns the sliding block to its original position once the Bowden cable  350  is released. 
         [0027]    If the trunk lid  300  is closed on the inoperable latch  200 , the striker  308  can engage and move the pawl  204  to the second latched position where the pawl  204  is held by the trigger  206  and the striker  308  is captured by the pawl slot  258 . This second or back-up latched configuration is illustrated in  FIGS. 28 and 29 . This arrangement allows the trunk lid  300  to be secured in a near closed position until the vehicle can be taken in for service. 
         [0028]    It is to be understood that the present invention is not limited to the embodiments disclosed above, but includes any and all embodiments within the scope of the appended claims.

Technology Classification (CPC): 4