BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates generally to crossbows, and in particular to trigger mechanisms for preventing firing of a crossbow without a bolt loaded therein.
2. Description of the Related Art
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 impacts 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.
In an attempt to overcome such problems, a dry fire inhibitor has been introduced in the form of a hinge lever or finger positioned along the crossbow barrel near the start of the string travel. The hinge lever is configured to normally contact the barrel, and insertion of an arrow creates a separation between the hinge lever and the barrel. 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.
Conventional dry fire inhibitors fail to ensure proper loading of an arrow or bolt into the trigger mechanism and fail ensure that the arrow is properly nestled against the tensioned crossbow string. Discharge when an 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.
The present invention provides an arrestor that solves the problems associated with conventional crossbow dry sore inhibitors.
SUMMARY OF THE INVENTION
The present invention overcomes disadvantages of conventional systems by providing a self-contained dry fire arrestor that includes a dry fire member and a spring which holds the dry fire member in engagement with a trigger mechanism to prevent firing the crossbow unless an arrow or bolt is loaded in the crossbow.
The present invention provides an advantage of an automatic safety feature by immobilizing the crossbow trigger when an arrow or bolt is not properly loaded.
The present invention provides a further advantage of precluding any string travel absent proper loading of an arrow.
The present invention provides yet a further advantage of avoiding misfires and jamming.
The present invention is lightweight, reliable and can be incorporated into the trigger mechanism.
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
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:
FIG. 1 is a cutaway view of the crossbow dry fire arrestor of the invention, in a cocked engagement position;
FIG. 2 is a disassembled view of the crossbow dry rare arrestor of FIG. 1;
FIG. 3 is a disassembled view of the crossbow dry fire arrestor of FIG. 1, also showing a trigger mechanism;
FIG. 4 is a close-up view of a portion of the trigger mechanism of FIG. 3;
FIG. 5 is a cutaway view of the crossbow dry fire arrestor of FIG. 1, showing movement directions of an anti-dry fire bar;
FIG. 6 is a disassembled view showing details of a slot of a trigger sear for engagement of the anti-dry fire bar;
FIG. 7 is a disassembled view of the crossbow dry fire arrestor of FIG. 1, showing engagement of the trigger sear with a shoulder region of an engaging member;
FIG. 8 is a disassembled view showing both halves of the casing of the dry fire arrestor;
FIG. 9 is a top view of the jaws, showing a jaw urging member and jaw member slot and other components;
FIG. 10 is a side view of the jaw urging member;
FIG. 11 shows compression of the jaw spring into its containment cavity and other components;
FIG. 12 shows a partially assembled dry fire arrestor;
FIG. 13 is a perspective view of a crossbow with a dry fire arrestor and a telescopic sight;
FIG. 14 is a side view of the crossbow with a telescopic sight, partially broken away;
FIG. 15 is a side view of the crossbow taken from the side opposite the side shown in FIG. 14; and
FIG. 16 is a view of dry fire arrestor and a mount for the telescopic sight.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following detailed description of the preferred embodiment 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 clarity in understanding the concept of the invention, as such would obscure the invention with unnecessary detail.
As shown in FIGS. 13-16 crossbow 100 includes stock 110, barrel 120, dry fire arrestor 200, telescopic sight 150 and sight mount 140 which secures the sight on arrestor 200. The crossbow 100 has limbs 160 and string 170.
FIG. 1 provides a cutaway view of the crossbow dry fire arrestor 200 in an engagement, i.e. cocked position, with a tensioned crossbow string (not shown) held between closed upper and lower jaws 260, 270 awaiting firing of the crossbow. Upper and lower jaws 260, 270 are shown in an open position in FIG. 12 and are shown in a closed (or cocked) position in FIGS. 1, 6 and 8.
Arrow 290 is shown being inserted between the jaws in direction “B” in FIG. 1. As shown in FIG. 9, an opening 252 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.
An upper curved portion 254 of anti-dry fire bar or member 225 is preferably provided to allow for frictional contact to hold arrow 290 in the dry fire arrestor 200.
A spring plate 210, shown disassembled from the dry fire arrestor 200 in FIGS. 1 and 2 and assembled in arrestor 200 in FIG. 16, is preferably affixed to each casing half 205 via respective affixing holes 211. The flexibility of the spring plate 210 when affixed to casing halfs 205 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). FIG. 5 shows the bar 225 in a down position below string slot 256 in casing halfs 205. FIG. 7 shows the bar in an up position with portion 254 extending into slot 256 in the casing halfs.
FIG. 2 shows the crossbow dry fire arrestor of FIG. 1, with a trigger sear 220 and engaging member 240 further disassembled, 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 242 as shown in FIGS. 3 and 4. The tension provided by spring plate 210 normally holds the bar 225 in the up position and allows anti-dry fire bar 225 to automatically engage trigger sear 225, which precludes any movement of the trigger when an arrow 290 is not properly inserted in the dry fire arrestor 200. The sear 220 extends through opening 258 in bar 225. When the bar is in the up position, the bottom edge of the opening is held in slot 221 in the sear to prevent movement of the sear. This automatic immobilizing of the trigger mechanism 242 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 200.
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 240.
Hole or opening 258 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 or opening 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 221 of trigger sear 220 precludes any movement of the trigger sear 220. FIG. 7 provides a disassembled view of the crossbow dry fire arrestor of FIG. 1, showing engagement of the sear 220 with the shoulder region 245 of engaging member 240, with spring plate 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 position. In this position, the upper corner 262 of the inner end 264 of the sear 220 in step or notch 266 in the adjacent face of region 245 on engaging or lock member 240.
Proper insertion of the arrow pushes the anti-dry fire bar 225 downward against spring 210, thereby freeing and allowing the trigger sear 220 to move forward and move corner 262 out of engagement with step 266. Forward movement of the trigger sear 220 permits the engaging member 240 to drop, thereby allowing jaw urging member 250 (not shown in FIG. 7) to move forward, resulting in upper and lower jaws 260, 270 opening via rotation about first and second jaw fulcrum posts 281, 282.
To provide opening/closing force for operation of the upper and lower jaws 260, 270, a jaw post 285 is provided in post groove 286 to hold, jaw spring 287 in a compressed state within a containment cavity 288 in the inner end of jaw urging member 250. For clarity, FIG. 1 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 50 and containment cavity 288. Access to the containment cavity 288 is provided via a jaw member slot 251 shown in FIGS. 9 and 10, through which the jaw post 285 passes (see FIG. 3), and via a distal or inner end 268 (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 post 285 through jaw member slot 251.
As shown in FIGS. 8-12, compression of jaw spring 287 in containment cavity 288 creates a tension force against jaw pin 285. FIG. 12 depicts the normally open position of upper and lower jaws 250, 270, awaiting insertion of the crossbow string, which pushes forward edges of the upper and lower jaws apart, creating a rotation force about first and second jaw fulcrum pins 281 and 282 (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. Rearward movement of member 250 closes jaws 260 and 270 on the crossbow string and moves the member to the position of FIG. 1. Spring 244 is fitted in recess 246 and holds member 240 in the position of FIG. 1 for engagement with sear 220. The sear holds member 250 against release until an arrow is loaded in the crossbow to move bar 225 down and out of slot 221 and free the sear for movement when the trigger is pulled.
Patent Grant
8020543
