Patent Publication Number: US-2010113195-A1

Title: Arrow nock including metal reinforcement member

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/110,260, filed 31 Oct. 2008. The entire disclosure of the referenced provisional application is incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field of the Invention 
     The invention relates to archery equipment in general, and bow hunting and target shooting of arrows in particular. The arrows include a nock for accommodating the bowstring until the arrow is propelled or otherwise removed from the bow. More particularly, the present invention relates to an improved nock including a metal reinforcement member embedded in a plastic nock body. 
     2. Background of the Invention 
     Many different types of arrows and arrow shafts are known for use in hunting and sport archery. A newly popular type of arrow shaft is the fiber reinforced polymer (FRP) arrow. FRP describes fiberglass composites and carbon fiber composites. Other arrow shafts are also constructed of aluminum and other light metals, wood and plastic. 
     In general, arrows include three portions, a shaft, a head and a tail portion including fletching and supporting a nock. The arrow shaft comprises a shaft having two ends, a fetching end and an arrowhead end, each end accommodating an attachment to complete the arrow. At the first end, an arrowhead of a design chosen by the shooter may be attached to the shaft. At the fetching end or second end, an arrow nock for supporting and propelling the arrow is attached. 
     It is advantageous to allow the sportsman to customize the arrow for the particular situation, such as hunting or target practice. If hunting, the customization could depend upon the type of game and the weather conditions, particularly wind conditions. Therefore, various types and sizes of arrowheads, arrow shafts and arrow nocks have been devised to accommodate the various styles and conditions individuals may encounter while hunting or taking target practice. 
     An arrow nock forms the rearward end of an arrow and generally has a pair of arms that form a substantially U-shaped notch for receiving the bowstring. The arrow nock is often made as a separate component that is affixed to the rearward end of the arrow shaft. In general, there are two types of arrow nocks, divergent and convergent. Arrow nocks having parallel arms or arms that diverge can allow the arrow to slip off of the bowstring as the bow is drawn. Arrow nocks can also be arranged with arms that converge to retain the arrow on the bowstring but can create frictional drag on the arrow during release from the bowstring. The type of arrow nock employed depends on the particular desires of the individual sportsman. 
     With the use of compound bows by today&#39;s sportsmen, large forces are placed on the arrow shaft and the attachments for the arrow, such as the nock, during the shooting, contact and removal of the arrow. Often, these forces result in the failure of the arrow shaft or the attachments, such as the arrowhead or the nock. In addition, the arrow shaft may flex during the aiming and shooting of the arrow to place additional stress at the point of the nock/shaft connection which could cause fatigue failure after repeated use. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides an improved nock to prevent these stresses from causing failure or fracture of the arrow or the arrow nock. The present invention provides an arrow nock that reduces nock flexure relative to the arrow shaft and thus prevents fatigue failure and provides better accuracy of the arrow. The nock includes a reinforcing member that extends the length of the nock. The nock is held by friction on the fletched end of the arrow shaft. The reinforcing rod or member provides greater strength at the junction of the arrow shaft and the nock where the nock receives the greatest amount of stress and force from the oscillations and flexing caused by the bowstring release. Stress is also placed on the nock when the arrow is removed from the target and when the arrow strikes the target. Often, with the use of compound bows, the forces created by the bowstring will propel the arrow through the target. The combination of these stresses can cause fatigue failure of the arrow, arrow shaft and nock. 
     In the arrow nock according to a first embodiment of the present invention, parallel arms form the bowstring opening and the reinforcing member is force fit into the nock. 
     In the arrow nock according to a second embodiment of the invention, converging arms form the bowstring opening and the reinforcing member is located within the nock body during the molding process. 
     In the arrow nock according to a third embodiment of the invention, diverging arms form the bowstring opening and the reinforcing member is molded into the nock body. 
     It is an object of the invention to provide a plastic arrow nock having a reinforcing member therein formed by plastic injection molding techniques. 
     It is an object of the invention to provide an arrow nock that reduces flexure of the nock relative to the shaft and prevents fatigue failure. 
     It is an object of the invention to provide a stiff nock that imparts more direct bowstring force to the arrow shaft. 
     These and other objects and advantages of the invention will become apparent in the detailed description. For a more detailed presentation of the invention, the following section offers a detailed description accompanied by drawings. Throughout the following detailed description and drawings, like numbers refer to like parts. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Details of this invention are described in connection with the accompanying drawings that bear similar reference numerals in which: 
         FIG. 1A  is a perspective view of a first embodiment of the invention; 
         FIG. 1B  is a perspective view in the opposite direction of the first embodiment shown in  FIG. 1A ; 
         FIG. 2  is a cutaway view of the first embodiment shown in  FIG. 1A ; 
         FIG. 3  is a top view of a second embodiment of the invention; 
         FIG. 4  is a top view of a third embodiment of the invention; 
         FIG. 5A  is a first end view of the first embodiment of the invention shown in  FIG. 1A ; and 
         FIG. 5B  is a second end view of the first embodiment of the invention shown in  FIG. 1A . 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     Describing the specific embodiments herein chosen for illustrating the invention, certain terminology is used which will be recognized as being employed for convenience and having no limiting significance. For example, the terms “forward”, and “rearward” refer to the illustrated embodiment in its normal position of use, affixed to an arrow and positioned onto a substantially vertical section of a bowstring. The terms “outward” and “inward” refer to lateral directions with reference to the axis of the device. Further, all of the above-defined terminology includes derivatives of the word specifically mentioned and words of similar import. 
     The present invention relates to an arrow system that may be used for archery, and particularly for bow hunting. It is advantageous to use an arrow shaft with the smallest possible diameter. A smaller diameter shaft has a smaller surface area for a cross wind or other external force to act upon. However, the smaller the diameter arrow shaft, the more flex and stress that is placed on the points of connection of the arrow head and arrow nock. Generally, archers prefer a smooth outer surface of the shaft without any projections, other than the fletching. This preference correlates with the general understanding that an arrow will have better aerodynamic efficiency with fewer structural projections on the outside of the arrow shaft. 
     The carbon-composite type arrows are generally lighter than aluminum shafts, but have the same spine. “Spine” is an industry-standard measurement describing the arrow shaft stiffness. However, lighter arrow shafts also were not as stiff or had less spine. Lighter arrow shafts have the advantage of higher velocities when launched from the same bow. Lighter arrow shafts also tend to flex or oscillate at release. This oscillation and/or flexing effects accuracy. Higher velocities result in a flatter arrow trajectory. The advantage of a flatter trajectory is that an error with respect to the range to a target has less effect on the point of impact. The arrow shaft being stiffer at the rear or nock end tends to produce better accuracy. Therefore, the attachments for the arrow shafts need to retain the advantages these lighter, thinner arrow shafts provide the sportsman. These attachments comprise the arrow head and the nock. The arrow nock is the object of the present application. 
     An arrow nock is provided at the rear of the arrow shaft rearward of the fletching and includes a notch or opening to allow the bowstring to engage the arrow to propel the arrow towards the target. As can be seen in  FIGS. 1A and 1B , the nock  10  in accordance with the invention is made of three clearly delineated sections. The nock body  10  comprises the reinforcing member  20 , the attachment portion  30 , and the nock portion  40 . In general, the nock  10  resembles three elongated, solid cylinders of increasing size, the nock portion  40  ending in the pair of arms  41 ,  42  ( FIGS. 1A ,  1 B,  2 ,  5 A and  5 B). 
     The nock portion  40  comprises a pair of arms  41 ,  42  spaced apart to form the bowstring opening or notch  43 . The pair of arms can be parallel to each other or diverge or converge as will be described later with respect to different embodiments of the nock  10 . 
     The nock portion  40  is larger in diameter than the attachment portion forming a stop  31  or shoulder that prevents the nock  10  from being inserted into the arrow shaft  1  too far. In addition, the free ends of the arms  44  may taper in thickness, longitudinally and transversely to aid in guiding the bowstring into the notch  43 . The longitudinal taper  45  can best be seen in  FIG. 2 . 
     Referring to  FIG. 2 , the arrow shaft  1  is shown in relation to the nock  10  and the attachment portion  30 . The nock  10  is inserted into the shaft  1  up to the stop or shoulder  31  formed by the nock portion  40 . The stop  31  is cylindrical to match the shape of the arrow shaft  1  in size and shape. As can best be seen in  FIG. 2 , the reinforcing member  20  is long enough to extend from the arms  41 ,  42  of the nock portion  40  through the attachment portion  30  and beyond the portion  30 . The attachment portion  30  releasably engages the arrow shaft  1  to allow for the changing of the nock  10 , if so desired. The nock  10  is preferably retained in the shaft  1  by friction or an interference fit within the shaft  1  allowing the shaft  1  to be free of projections as discussed earlier. Alternatively, adhesives could be used to ensure the nock  10  is secured to the shaft  1 . Depending on the type of shaft  1  (carbon, aluminum, wood), different procedures for preparing the shaft for adhesives would be required. The length of the attachment portion  30  allows the nock  10  to be frictionally retained within the shaft  1 . The attachment portion  30  could include serrations or roughness (not shown) on the surface to increase the frictional engagement of the attachment portion  30 . 
     The reinforcing member  20  prevents the flexing of the nock  10  relative to the shaft  1  to prevent flexing, which could cause fatigue failure and allows better transfer of the bowstring energy to the arrow. The failure could occur at the nock  10  between portions  31  and  21  or in the arrow shaft  1  adjacent the end at the juncture with the nock  10 . 
     The reinforcing member  20  is preferably a unitary metallic rod injection molded into the nock  10 . The reinforcing member  20  extends beyond the end of the attachment portion  30  and acts as a guide for inserting the nock  10  onto the arrow shaft  1 . The smaller diameter of the member  20  guides the nock  10  to be easily inserted into the shaft  1 . The reinforcing member  20  could comprise other equally stiff materials that could be formed into a cylinder, such as carbon-fiber or ceramics. 
     The attachment portion  30  and nock body  40  are substantially the same length. These members are injection molded plastic that encloses the reinforcement member  20  Alternatively, the portion  30  and body  40  could be formed with a hole therein that would accommodate the reinforcing member  20 . Adhesive could be used to further attach the member  20  to the portion  30  and body  40 . 
     As can be seen in  FIGS. 3 and 4 , second and third embodiments of the invention are provided with variations of the pair of arms  41 ,  42  of the first embodiment being illustrated. Referring to  FIG. 3 , the converging arms  41 ′,  42 ′ are provided to retain the bowstring  2  in the notch. The gap  45  is slightly smaller than the diameter of the bowstring  2 . Thus, the arms  41 ′,  42 ′ flex slightly to allow the bowstring to pass through the gap  45 . Referring to  FIG. 4 , the third embodiment is similar to the first embodiment that has the arms parallel. The arms  41 ″,  42 ″ diverge and taper to guide the bowstring into the notch as shown. Other shapes of the arms  41 ,  42  could be provided. 
     Although a selected illustrative embodiment of the present invention has been described with specificity herein, the foregoing description is intended to be an illustration, and not a restriction in the scope of the invention. Those skilled in the art will realize that many modifications of the preferred embodiment could be made which would be operable.