Abstract:
Disclosed in a dry fire arrestor for a crossbow having a trigger mechanism operable to fire an arrow or bolt, that includes a spring plate, trigger sear connected to the trigger mechanism, an anti-dry fire bar for engaging and disengaging the trigger sear. The dry fire arrestor utilizes tension provided by the spring plate to allows anti dry fire bar to automatically engage the trigger sear, precluding movement of the trigger when an arrow in not properly inserted in the dry fire arrestor.

Description:
PRIORITY 
       [0001]    This application claims priority to provisional application Ser. No. 60/881,076, filed with the U.S. Patent and Trademark Office on Jan. 18, 2007, the contents of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of Invention 
         [0003]    The present invention relates generally to crossbows, and in particular to trigger mechanisms for preventing firing of a crossbow without a bolt loaded therein. 
         [0004]    The present invention relates generally to crossbows, and in particular to a mechanism for compensating for firing error in a crossbow. 
         [0005]    2. Description of the Related Art 
         [0006]    Crossbows have been used since the middle ages. Crossbows have evolved to include cams and synthetic split limbs that greatly increase firing velocity. However, increased firing velocity creates a problem of damage or injury when the crossbow is inadvertently fired when unloaded, i.e. when the crossbow is discharged without a bolt (also referred to as an arrow) that is loaded, i.e. pressed against the tensioned crossbow string. Unloaded or dry firing imparts can damage the crossbow string, limbs, cams and other components. Dry firing also creates a safety concern. Further, the time required to reload a dry fired crossbow will often allow quarry to escape, which is a significant concern for crossbow hunters. 
         [0007]    In an attempt to overcome such problems, a dry fire inhibitor has been introduced in the form of a hinge lever or finger (referred to herein as a finger) positioned along the crossbow shaft near the start of the string travel. The finger is configured to normally contact the shaft, and insertion of an arrow creates a separation between the hinge lever and the shaft. When dry fired, the string will travel a short distance and then the finger will catch the string, akin to the operation of an aircraft carrier tail hook arrestor. 
         [0008]    Conventional dry fire inhibitors also fail to ensure proper loading of the bolt into the trigger mechanism and fail to ensure that the arrow is properly nestled against the tensioned crossbow string. Discharge when a arrow is not properly nestled against the tensioned string can result in the string becoming jammed beneath the incorrectly loaded arrow. In addition, conventional dry fire inhibitors may ride along the arrow as the arrow is discharged, reducing crossbow accuracy. 
         [0009]    The present invention provides an arrestor that solves the problems associated with conventional crossbow dry fire inhibitors. 
         [0010]    The present invention further provides an impact compensator that allows for one-handed dynamic adjustment for varied target range. In contrast, conventional compensators provide a one-time setting. The impact compensator is preferably provided separate from a conventional sight. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention overcomes disadvantages of conventional systems by providing a self-contained dry fire arrestor that includes 
         [0012]    The present invention provides an advantage of an automatic safety feature by immobilizing the crossbow trigger when a bolt is not properly loaded. 
         [0013]    The present invention provides a further advantage of precluding any string travel absent proper loading of an arrow. 
         [0014]    The present invention provides yet a further advantage of avoiding misfires and jamming. 
         [0015]    The present invention is lightweight, reliable and can be incorporated into the trigger mechanism. 
         [0016]    The dry fire arrestor of the present invention can, if desired, be combined with the above-described conventional dry fire inhibitors. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0017]    For a better understanding of the invention as well as other objects and further features thereof, reference is made to the following detailed description to be read in conjunction with the accompanying drawings, wherein: 
           [0018]      FIG. 1  is a cutaway view of the crossbow dry fire arrestor of the invention, in an cocked engagement state; 
           [0019]      FIG. 2  is a dissembled view of the crossbow dry fire arrestor of  FIG. 1 ; 
           [0020]      FIG. 3  is a dissembled view of the crossbow dry fire arrestor of  FIG. 1 , also showing a trigger assembly; 
           [0021]      FIG. 4  is a close-up view of a portion of the trigger assembly of  FIG. 3 ; 
           [0022]      FIG. 5  is a cutaway view of the crossbow dry fire arrestor of  FIG. 1 , showing a movement direction of an anti dry fire bar; 
           [0023]      FIG. 6  is a view showing details of a slot of a trigger sear for engagement of the anti dry fire bar; 
           [0024]      FIG. 7  is a dissembled view of the crossbow dry fire arrestor of  FIG. 1 , showing engagement of the trigger sear with a shoulder region of an engaging member; 
           [0025]      FIG. 8  is a dissembled view showing both halves of the casing of the dry fire arrestor; 
           [0026]      FIG. 9  is a top view of the jaws, showing a jaw urging member and jaw member slot; 
           [0027]      FIG. 10  is a side view of the jaw urging member; 
           [0028]      FIG. 11  shows compression of the jaw spring into its containment cavity; 
           [0029]      FIG. 12  shows a partially assembled dry fire arrestor; 
           [0030]      FIG. 13  is a perspective view through a sight mounted onto an impact compensator assembled onto the crossbow; 
           [0031]      FIG. 14  shows the impact compensator mounted onto stock; 
           [0032]      FIG. 15  shows the impact compensator being removed from the stock; 
           [0033]      FIG. 16  shows manipulation of a pivoting sight of the impact compensator; 
           [0034]      FIG. 17  shows the pivoting sight rail removed from the impact compensator; 
           [0035]      FIG. 18  shows the pivoting sight rail assembled with the impact compensator and compensator adjusting wheel; 
           [0036]      FIG. 19  is a perspective view of impact compensator; 
           [0037]      FIG. 20  is a perspective view of impact compensator with the compensator wheel removed; and 
           [0038]      FIG. 21  is a perspective view of a horizontal impact compensator. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0039]    The following detailed description of preferred embodiments of the invention will be made in reference to the accompanying drawings. In describing the invention, explanation about related functions or constructions known in the art are omitted for the sake of clearness in understanding the concept of the invention, as such would obscure the invention with unnecessary detail. 
         [0040]      FIG. 1  provides a cutaway view of the crossbow dry fire arrestor in an engagement, i.e. cocked, state, which is the condition of tensioning a crossbow string (not shown), which would be held between upper and lower jaws ( 260 ,  270 ) awaiting firing of the crossbow. Upper and lower jaws ( 260 ,  270 ) are shown in an open state in  FIG. 12  and are shown in a closed (or cocked) state in  FIGS. 1 ,  6  and  8 . 
         [0041]    Arrow  290  is shown being inserted between the jaws in direction “B” in  FIG. 1 . As shown in  FIG. 9 , an opening is provided at the center of each of upper and lower jaws ( 260 ,  270 ) through which arrow  290  is held. It is preferable to provide both upper and lower jaws ( 260 ,  270 ) to hold the crossbow string at a position that is not in contact with the barrel  120  of the crossbow  100 , thereby reducing string wear and improving firing accuracy. In contrast, conventional crossbow string holders utilize a single action gate that presses the string against the barrel  120 . 
         [0042]    An upper curved portion of anti dry fire bar  225  is preferably provided to allow for frictional contact to hold arrow  290  in the dry fire arrestor  200 . 
         [0043]    A spring plate  210 , shown dissembled from the dry fire arrestor  200  in  FIGS. 1 and 2 , is preferably affixed to each casing half  205  via respective affixing holes  211 . The flexibility of the spring plate  210  provides upwardly biases the anti dry fire bar  225 . Insertion of the arrow  290  overcomes the upward biasing force, and moves the anti dry fire bar downward ( FIG. 5 ). 
         [0044]      FIG. 2  shows the crossbow dry fire arrestor of  FIG. 1 , with a trigger sear  220  and engaging member  240  further dissembled, and with crossbow string holding jaws removed. The anti dry fire bar  225  engages and disengages with trigger sear  220 , which is connected to a conventional trigger mechanism as shown in  FIGS. 3 and 4 . The tension provided by spring plate  210  allows anti dry fire bar  225  to automatically engage trigger sear  225 , which precludes any movement of the trigger when an arrow  290  in not properly inserted in the dry fire arrestor  200 . This automatic immobilizing of the trigger mechanism acts in addition to a conventional thumb safety lock. In the present invention, pressure of the crossbow string neither activates nor precludes operation of the anti dry fire mechanism. 
         [0045]    Pulling the crossbow trigger exerts a forward motion (“A” in  FIG. 1 ) on trigger sear  220 , which abuts a shoulder region  245  of engaging member  240 . As shown in  FIG. 2 , shoulder region  245  protrudes slightly below the otherwise flat bottom surface of jaw urging member  250 . 
         [0046]    A hole in the anti dry fire bar  225  through which trigger sear  220  passes is shown in  FIGS. 2 and 6 . Trigger sear  220  is provided with slot  221  that engages a lower edge of the hole when an arrow  290  is not properly inserted in the dry fire arrestor  200 . Engagement of the anti dry fire bar  225  with the slot of trigger sear  220  precludes any movement of the trigger sear  220 .  FIG. 7  provides a dissembled view of the crossbow dry fire arrestor of  FIG. 1 , showing engagement of the sear  220  with a shoulder region  245  of engaging member  245 , with spring  210  removed to allow the anti dry fire bar  225  to protrude below the casing  205 , which will allow the jaws to remain in the cocked state. 
         [0047]    Proper insertion of the arrow pushes the anti dry fire bar  225  downward, thereby freeing and allowing the trigger sear  220  to move forward. Forward movement of the trigger sear  220  causes the engaging member  240  to drop, thereby allowing jaw urging member  250  to move forward, resulting in upper and lower jaws ( 260 ,  270 ) opening via rotation about first and second jaw fulcrum ( 281 ,  282 ). 
         [0048]    To provide opening/closing force for operation of the upper and lower jaws  260 ,  270 , a jaw post  285  is provided to hold a jaw spring  287  in a compressed state within a containment cavity  288 . For clarity,  FIG. 8  shows jaw post  285  removed but positioned near the post groove  286  in casing  205 .  FIG. 9  provides a top view of the jaws, showing jaw urging member  250  and containment cavity  288 . Access to the containment cavity  288  is provided via a jaw member slot  251  ( FIG. 10 ), through which the jaw post  285  passes (see  FIG. 3 ), and via a distal end ( FIGS. 2 and 11 ) of jaw urging member  250 .  FIG. 10  provides a side view of the jaw urging member  250 , showing jaw spring  287  protruding from its containment cavity via the distal end of jaw urging member  250 , and  FIG. 11  shows compression of the jaw spring  287  into its containment cavity for insertion of jaw spring support  288  through jaw member slot  251 . 
         [0049]    As shown in  FIGS. 8-12 , compression of jaw spring  287  in containment cavity  288  creates a tension force against jaw spring support  288 .  FIG. 12  depicts the normally open position of upper and lower jaws ( 260 ,  270 ), awaiting insertion of the crossbow string, which pushes forward edges of the upper and lower jaws apart, creating a rotation force about first jaw fulcrum  281  ( FIGS. 1 and 7 ) and pushing the jaw urging member  250  in a rearward direction (arrow “C” of  FIG. 1 ). The jaw spring  287  force opposes such rearward pushing of jaw urging member  250 . 
         [0050]      FIG. 13  provides a perspective view of the crossbow, looking through a sight  150  of impact compensator  120 . As shown in  FIG. 14 , the impact compensator  120  is mounted onto stock  110 . The sight  150  removed in  FIG. 14 , and  FIG. 15  shows the impact compensator  120  being removed from the stock  110 .  FIG. 17  shows pivoting sight rail  160  removed from the impact compensator  120 . When assembled, a spring force holds the pivoting sight rail  160  close to the main body  121  of the impact compensator. 
         [0051]    As shown in  FIG. 16 , sight rail  160  pivots about an impact compensator pivot  135 , in a rotational direction indicated by arrow “D” ( FIG. 18 ). A compensator adjusting wheel  140  is provided to allow the user to adjust the extent of rotational movement of pivoting sight rail  160  while viewing a target through the sight  150 . A retaining ring  149  ( FIG. 18 ) is provided to rotatably hold a pin  145  of the compensator adjusting wheel  140  within a hole  146  ( FIG. 20 ) of the impact compensator  120 . 
         [0052]    Elevational protrusions  140   a  through  140   f  of the compensator adjusting wheel  140  sequentially push against an elevation cam  180  affixed to the pivoting sight rail  160 . The elevational protrusions  140   a  through  140   f  are of varying height, and a notch  181  is provided in the elevation cam  180  to retain one selected elevational protrusion  140   a  through  140   f  and provide the user with a click through adjustment.  FIG. 20  provides a perspective view of impact compensator  120  with the compensator wheel  140  removed, showing elevational protrusions  140   a  through  140   f  spaced at regular interval around a circumference of the compensator wheel for contacting a shoulder region of elevation cam  180 , to incrementally raise the height of the pivoting sight rail  160  as a user turns compensator wheel  140 . 
         [0053]    As shown in  FIG. 18 , sight  150  is attached to the impact compensator rail  160 , and the pivoting movement about impact compensator pivot  125  via adjustment of compensator wheel  140  will adjust the range of the sight  150 . As shown in  FIG. 14 , range marking are preferably provided on compensator wheel  140 . It is also preferred that an outer circumference of compensator wheel  140  be abraded or knurled to enhance friction and sensitivity.