Patent Publication Number: US-6213113-B1

Title: Bowstring draw mechanism

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to an archery device and, in particular, to a mechanism for assisting an archer in drawing back a bowstring. 
     DESCRIPTION OF THE RELATED ART 
     Archery has continued to increase in popularity, both as a sport and as recreational activity, for target shooting and hunting. One of the most popular types of bows in current use is the compound bow. Compound bows employ a relatively complex cable and pulley arrangement in which the geometry of the system is quite critical. As a result of the pulley arrangement, the maximum draw of the bowstring is exerted only during the first ½ or {fraction (2/3+L )} of its displacement. As the bowstring is drawn back towards its maximum deflection, a sudden reduction in draw pressure is experienced (as much as 80%), whereafter the archer may easily draw the bowstring back through the remaining draw distance. 
     However, in spite of the reduction in draw pressure, there is still a required, substantial, initial draw pressure which, even after shooting just a few times, can result in muscle fatigue and cramping of the archer&#39;s arm and shoulder, often leading to inaccuracy. Additionally, persons of lesser strength, or with chronic or debilitating shoulder injuries, may be unable to achieve even this initial draw pressure. 
     As a result, there are a number of devices which purport to assist the archer in drawing back the bowstring. One class of such devices is the draw and release mechanism, as illustrated in U.S. Pat. Nos. 3,952,720; 4,308,851; 4,665,886; 4,969,448; 5,078,116; and 5,845,286, the disclosures of which are incorporated herein by reference. This class includes devices which are hand-held or strapped to the wrist and have a trigger which permits the archer to release the bowstring. While this class of devices assists the archer in securely gripping the bowstring and smoothly releasing it, the devices do not provide any assistance in drawing back the bowstring. 
     Another class of devices includes the pre-cocking mechanisms, as illustrated in U.S. Pat. Nos. 5,000,154 and 5,065,730, the disclosures of which are incorporated herein by reference. This type of pre-cocking mechanism permits the bowstring to be drawn back and held in position prior to the knocking of an arrow. While these devices will hold the bowstring in a drawn position, they do not provide any assistance in the drawing back of the bowstring. 
     Accordingly, there is a need in the art for a device which assists in the drawing back of the bowstring and improves an archer&#39;s accuracy by decreasing muscle fatigue resulting from drawing back the bowstring. There is also a need in the art for a device which would open the sport of archery to a greater audience by decreasing the physical demands of the sport. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention describes a mechanism for assisting an archer in drawing back a bowstring. The bowstring draw assist mechanism preferably includes two interactive components. The first component is a support frame affixed to the bow, and the second component is a gauntlet worn by the archer. 
     More specifically, the support frame is removably affixed to the bow, providing a stable point to which the gauntlet engages. The support frame comprises an upper and lower cable guard, where the upper and lower cable guards are affixed to the bow&#39;s upper and lower extensions forming an offset plane parallel to the bow plane, thereby positioning the cables an offset distance from the bow plane. A cross bar comprising a push-head is perpendicularly affixed to the ends of the upper and lower cable guards. The push-head is positioned substantially planar to the firing plane. 
     The gauntlet is worn on the forearm of the archer, comprising a forearm sleeve and a glove. The forearm sleeve is securely attached to the glove. The forearm sleeve further comprises a cylinder pocket positioned along the exterior surface and substantially traverses the longitudinal length of the forearm sleeve. The cylinder pocket is situated such that a compressed gas actuated cylinder can be secured into the cylinder pocket. The gauntlet is secured about the archer&#39;s forearm by inserting the archer&#39;s hand into the glove and securing the forearm sleeve about the archer&#39;s forearm with the straps. 
     The compressed gas actuated cylinder comprises a rod with a piston fixed to one end and a rod-head fixed to the opposite end. The piston and rod are slidably fitted into the cylinder. The cylinder comprises an air inlet for connection to a compressed gas delivery system. 
     The compressed gas delivery system comprises a compressed gas tank fitted with an adjustable regulator. The delivery system further comprises a valve and switch, whereby the switch opens the valve thereby pressurizing the cylinder. The delivery system is attached to the cylinder at the air inlet with an appropriately rated air hose and connector. 
     In operation, an archer grips the bow, while simultaneously nocking an arrow and positioning the rod-head into the push-head. The archer pulls back on the bowstring and depresses the switch opening the valve. The compressed gas pressurizes the cylinder, extending the rod and pushing the rod-head into the push-head. When the bowstring is in the fully extended position, the switch is released, thereby closing the valve. Upon release of the arrow, the cylinder is vented, retracting the rod. 
     Therefore, it is an object of the present invention to assist in the drawing back of the bowstring and to improve an archer&#39;s accuracy, by decreasing muscle fatigue resulting from drawing back the bowstring. Further, an objective of the present invention is to open the sport of archery to a greater audience by decreasing the physical demands of the sport. 
     These and other objects, features and advantages of the present invention will be more readily understood with reference to the following detailed description, read in conjunction with the accompanying drawing figures. 
     All patents, patent applications and publications referred to or cited herein, or from which a claim for benefit of priority has been made, are incorporated by reference in their entirety to the extent they are not inconsistent with the explicit teachings of this specification. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a side view of a compound bow including the cross bar and push-head elements of the present invention. 
     FIG. 2 shows a rear view of a compound bow including the cross bar and push-head elements of the present invention. 
     FIG. 3 shows a perspective view of the cable guards of the present invention. 
     FIG. 4 shows a side view of the cross bar with the push-head of the present invention. 
     FIG. 5 shows a perspective view of the push-head of the present invention. 
     FIG. 6 shows an alternative embodiment of the side view of the cross bar with push-head components of the present invention. 
     FIG. 7 shows an alternative embodiment of the side view of the cross bar with push-head components of the present invention. 
     FIG. 8 shows an alternative embodiment of the side view of the cable guides and cross bar components of the present invention. 
     FIG. 9 shows a front side view of the forearm sleeve and glove of the present invention. 
     FIG. 10 shows a rear side view of the forearm sleeve and glove of the present invention. 
     FIG. 11 shows a side view of the cylinder and piston in the retracted position. 
     FIG. 12 shows a side view of the cylinder and piston in the extended position. 
     FIG. 13 shows the compressed gas delivery system of the present invention. 
     FIG. 14 shows the operation of the present invention. 
    
    
     DETAILED DISCLOSURE OF THE INVENTION 
     As shown in FIGS. 1-14, the bowstring draw assist mechanism of the present invention includes two interactive components. The first component, a support frame  19 , is affixed to the bow  10 ; and the second component, a gauntlet  39 , is worn by the archer. 
     Referring now to FIGS. 1-5, the support frame  19  is removably affixed to the bow  10 , providing a stable point to which the gauntlet  39  engages. As shown in FIGS. 1-3, in a preferred embodiment, the support frame  19  comprises an upper and lower cable guard  20 ,  21 , whereby the upper cable guard  20  is affixed to the upper extension  16  of the bow&#39;s  10  grip, and the lower cable guard  21  is affixed to the lower extension  18  of the bow&#39;s  10  grip. The upper and lower cable guards  20 ,  21  are affixed to the bow  10  forming an offset plane  34  parallel the bow plane  32 , such that the cables  28  are positioned an offset distance from the bow plane  32 . 
     A cross bar  23  is affixed to the ends of the upper and lower cable guards  20 ,  21 , whereby the cross bar  23  is perpendicular to the upper and lower cable guards  20 ,  21 . As shown in FIGS. 4-5, the cross bar  23  comprises a push-head  24 , whereby the push-head  24  is positioned substantially planar to the firing plane  36 . 
     In an alternative embodiment, the distance between the offset plane  34  and the bow plane  32  is adjustable. The distance is increased by rotating the offset arm  22  of cable guards  20 ,  21  away from the bow plane  32 , achieving a maximum distance when the cable guards  20 ,  21  are perpendicular to the bow plane  32 . Similarly, the distance is decreased by rotating the offset arm  22  towards the bow plane  32 , achieving a minimum distance when the cable guards  20 ,  21  are parallel to the bow plane  32 . 
     In another embodiment, as shown in FIG. 8, the cross bar  23  is slidably connected to the ends of the cable guards  20 ,  21 , such that the cable guards  20 ,  21  may be simultaneously rotated while maintaining the push-head  24  in a position substantially planar to the firing plane  36 . The cross bar  24  is held in position by means of an allen screw  29  or other similar securing means. 
     In a further embodiment, as shown in FIG. 6, the push-head  24  is adjustable along the length of the cross bar  23 . The push-head  24  is slidably affixed about the cross bar  23 , being held in position with an allen screw  25  or other similar securing means. 
     Alternatively, as shown in FIG. 7, the cross bar  23  comprises a plurality of pin holes  27 , with the push-head  24  having a corresponding pin hole  26 . The push-head  24  is held in position with a cotter, or push pin, or other similar device. 
     In an alternative embodiment, the support frame  19  comprises a single cable guard  20 . The push-head  24  is connected to the end of the offset  22 , with the cable guard  20  being attached to the bow  10  such that the push-head  24  is in a position substantially planar to the firing plane  32 . 
     Similarly, the bowstring draw assist mechanism of the present invention can be used with a conventional bow, whereby the support frame  19  is attached to the conventional bow in substantially the same manner as the compound bow. 
     Referring now to FIGS. 9-13, the gauntlet  39 , which is worn by the archer, comprises a forearm sleeve  40  and a glove  42 , whereby the forearm sleeve  40  is securely affixed to the glove  42 . The forearm sleeve  40  comprises a cylinder pocket  44 , which is positioned along the exterior surface and substantially traverses the longitudinal length of the forearm sleeve  40 . The cylinder pocket  44  comprises an open front end and a substantially closed back end, whereby a compressed gas actuated cylinder  50  can be removably secured into the cylinder pocket  44 , through the open front. The gauntlet  39  is secured to the archer by inserting the archer&#39;s hand into the glove  42  and securing the forearm sleeve  40  about the archer&#39;s forearm with the straps  46 . 
     In an alternative embodiment, the gauntlet  39  is secured to the archer by inserting the archer&#39;s hand through the forearm sleeve  40  into the glove  42 , whereby the forearm sleeve  40  surrounds the archer&#39;s forearm. 
     As shown in FIGS. 11-12, the compressed gas actuated cylinder  50  comprises a rod  52 , with a piston  51  affixed to one end and a rod-head  54  affixed to the opposite end, whereby the piston  51  and rod  52  are slidably fitted into the cylinder  50 . The piston  51  divides the interior space of the cylinder  50  into a first chamber and a second chamber, whereby the rod  52  slides through the second chamber. The cylinder  50  further comprises an air inlet  56 , which is in communication with the first chamber, for the connection of a compressed gas delivery system  58 , to provide compressed gas into the first chamber. 
     As shown in FIG. 13, the compressed gas delivery system  58  comprises a compressed gas tank  72  fitted with an adjustable regulator  64 . The adjustable regulator  64  enables the gas pressure to be adjusted from about 10 psi-75 psi. The delivery system  58  further comprises a valve  66  and switch  70 , whereby the switch  70  opens the valve  66 , pressurizing the cylinder  50 . The delivery system  58  is attached to the cylinder  50  at the air inlet  56  with an appropriately rated air hose  74  and connector  60 . 
     In a method of use, as shown in FIG. 14, an archer grips the bow  10 , while simultaneously nocking an arrow and positioning the rod-head  54  into the push-head  24 . To draw back the bowstring  30 , the archer pulls back on the bowstring  30 , depressing the switch  70 , thereby opening the valve  66 . The compressed gas pressurizes the cylinder  50 , extending the rod  52 , and pushing the rod-head  54  into the push-head  24 . When the bowstring  30  is in a fully extended position, the switch  70  is released, thereby closing the valve 66 . 
     In a preferred embodiment, the rod  52  remains in the extended position, assisting the archer in maintaining the bowstring  30  in the fully extended position while aiming. Upon release ofthe arrow, the cylinder  50  is vented by opening the pressure relief valve  53 , thereby retracting the rod  52 . 
     In an alternative embodiment, the valve  66  is a three-way valve. In a first position, the valve  66  is closed. In a second position, the valve  66  is open to the compressed gas, thereby pressurizing the cylinder  50  and extending the rod  52 . In the third position, the valve  66  is open to the atmosphere, thereby venting the cylinder  50  and retracting the rod  52 . 
     In an alternative embodiment, the drawstring assist mechanism is be used in conjunction with a draw and release device, whereby the archer utilizes the draw and release device to grip and release the bowstring  30 . 
     It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and the scope of the appended claims.