Abstract:
A nock adapter for a solid shaft bowfishing arrow fits on a standard conical taper of a solid shaft arrow and provides an extended cylindrical joint releasably engaging a cylindrical boss of a nock for field replacement of the nock while resisting lateral disengaging impacts.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Patent Application 61/339,488 filed Mar. 5, 2010 and hereby incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to arrows used for bowfishing and in particular to a nock adapter suitable for use with such arrows. 
       BACKGROUND OF THE INVENTION 
       [0003]    A nock is the portion of an arrow that receives the bowstring to hold the end of the arrow in alignment with the bowstring prior to release. A nock may be a simple notch in the end of the arrow but more typically is a separate part which may be attached to the arrow. 
         [0004]    It is known to provide for nock adapters that serve to releaseably hold a nock to the arrow shaft permitting simplifying the replacement of the nock or the use of different nocks. For conventional arrows having tubular shafts, the nock adapter may include a foreword extending cylindrical boss that may fit within the tube of the arrow and it may provide an opposed bore for receiving a corresponding cylindrical boss of the nock. 
         [0005]    Bowfishing is a form of archery using arrows specially adapted for fishing. Bowfishing arrows normally do not have fletching (feathers) which may cause the arrow to move erratically in the water and may have a barbed arrowhead that allows for the releasing of the fish. Bowfishing arrows are normally attached to a tether that automatically follows the flight of the arrow and provides a means for retrieving the arrow and fish. 
         [0006]    Bowfishing arrows are typically solid shaft arrows, for example, constructed of fiberglass-reinforced polymer. Such arrows often provide a tapered rear end to be received by a conical bore in the nock which is glued to this taper. A nock adapter suitable for use with standard solid shaft arrows having tapered rear ends is taught in U.S. Pat. No. 5,919,105 hereby incorporated by reference. This nock adapter provides for a conical bore that may be attached to the conical end of the arrow and which provides an opposed conical projection and snap fitting that may be received and retained by a conical bore of a nock specially designed to engage the snap fitting. 
         [0007]    The nocks of bowfishing arrows, because of their intended use, are frequently exposed to sideward impacts caused by a striking of the arrow against the boat, the river bottom or the like such as may dislodge or break the nock. Accordingly, any attachment method for a bowfishing arrow must resist strong dislodgment forces. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention provides a nock adapter for bowfishing arrows that provides opposed conical and cylindrical bores allowing an improved engagement between the nock and the nock adapter by a simple press fit. This attachment method permits replacement of a nock while retaining the nock against dislodgment by sideward blows. It has been determined that high-strength materials can accommodate the additional torsional forces on the adapter caused by its increased length and that such materials may be suitably bonded to the arrow shaft. 
         [0009]    Specifically, the present invention provides an arrow assembly including a solid arrow shaft extending along an axis and having a conically tapered rear end and an adapter having a forwardly open conical bore receiving the rear end of the arrow shaft to align an axis of the adapter with the arrow axis by interfitting of the conical bore and tapered rear end and having a rearwardly opening bore with substantially parallel wall. A nock having a bifurcated rearward portion provides opposed fingers for fitting a bowstring therebetween and has a forwardly extending boss adapted to press fit within the rearwardly opening bore of the adapter to align the nock with the arrow axis. 
         [0010]    It is thus a feature of at least one embodiment of the invention to provide a nock adapter permitting simple replacement of nocks on bowfishing arrows while resisting dislodgment of the nocks with anticipated sideward impacts. 
         [0011]    The rearwardly extending bore of the adapter is substantially cylindrical. 
         [0012]    It is thus a feature of at least one embodiment of the invention to provide a simple joint between the nock and the nock adapter that can be used with readily available nocks. 
         [0013]    The rearwardly extending bore of the adapter may have an axial length no less than one and one half times its inner diameter. 
         [0014]    It is thus a feature of at least one embodiment of the invention to provide a joint that does not require particular ancillary attachment methods such as snaps or threads for retaining a nock in engagement and alignment 
         [0015]    The conically tapered rear end of the arrow may be conical or frusto-conical. 
         [0016]    It is thus a feature of at least one embodiment of the invention to work with a variety of solid shaft arrows using a readily fabricated joint shape. 
         [0017]    The forwardly open conical bore of the adapter may include a counterbore at its apex providing a glue relief volume. 
         [0018]    It is thus a feature of at least one embodiment of the invention to permit the use of the nock adapter with conically tipped arrows without misalignment caused by float of the nock adapter on an adhesive layer. 
         [0019]    The adapter may be nylon 
         [0020]    It is thus a feature of at least one embodiment of the invention to provide a material that may resist strong impacts expected with bowfishing arrows and yet which may be attached to a bowfishing arrow by adhesive. 
         [0021]    The forward extending boss of the nock is substantially cylindrical and/or may provide a set of diametrically protruding ridges extending along an axis of the boss. 
         [0022]    It is thus a feature of at least one embodiment of the invention to provide a simple joint that may be press fit or released in the field without special equipment. 
         [0023]    The adapter may have a cylindrical outer periphery substantially equal to a diameter of a cylindrical outer periphery of the solid arrow 
         [0024]    It is thus a feature of at least one embodiment of the invention to preserve the aerodynamic integrity of the arrow. 
         [0025]    The nock may be a thermoplastic material different from the adapter. 
         [0026]    It is thus a feature of at least one embodiment of the invention to provide an adapter likely to survive with the impacts that would break nocks. 
         [0027]    The nock may provide a maximum diametrical extent no greater than a diameter of a cylindrical outer periphery of the adapter 
         [0028]    It is thus a feature of at least one embodiment of the invention to provide an adapter that preserves the aerodynamic properties of the arrow. 
         [0029]    Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings in which like numerals are used to designate like features. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]      FIG. 1  is a fragmentary side elevational view of an arrow having a nock adapter of the present invention; 
           [0031]      FIG. 2  is a detailed cross-section of the nock adapter of  FIG. 1  as fit to the arrow shaft and a nock; 
           [0032]      FIG. 3  is a fragmentary perspective view in exploded form of the nock adapter, arrow shafts, and nock of  FIG. 2 ; and 
           [0033]      FIG. 4  is a figure similar to that of  FIG. 3  showing an alternative embodiment of the nock adapter. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0034]    Referring now to  FIG. 1  a bow-fishing arrow  10  may have a shaft  12 , for example, of fiberglass-reinforced polymer, carbon reinforced polymer or fiberglass carbon polymer extending generally along an axis  17  and having a diameter of substantially 0.3 inches and between ¼″ and ⅜″. A forward end of the shaft  12  may attach to an arrowhead  15  having rearwardly angled extending barbs  14 . 
         [0035]    The arrowhead  15  may be, for example, an AMS Shure Shot Arrow point commercially available from AMS Bowfishing of Stratford, Wis. providing a sharpened metallic tip  16  and incorporating a screw mechanism (not shown) allowing a turning of the shaft  12  with respect to the arrowhead  15  to release the barbs  14  for withdrawal of the arrowhead  15  from a fish (not shown) without the need to push the point through the fish. 
         [0036]    Referring also to  FIGS. 2 and 3 , a rear end of the shaft  12  may be sharpened into a conical tip  18  (or a frusto-conical tip  18 ′) according to prior art techniques intended to allow attachment of the shaft  12  to a nock (not shown) having a corresponding conical bore. The conical forming of the rear end of the shaft  12  may be done simply by a centerless grinding operation. 
         [0037]    The nock adapter  20  of the present invention may provide for a cylindrical outer surface  27  generally having a diameter  23  generally matching the corresponding diameter of the cylindrical outer surface of the shaft  12  (e.g. having equal diameters) and a forward facing conical bore  22  sized to conform with the angle of the conical tip  18  of the shaft  12 . The angle of the conical bore  22  may be, for example, substantially 23° and centered about the axis  17 . The conical bore  22  may terminate in a cylindrical counter bore  24  extending from its apex having a diameter, for example, of 0.145 inches. The cylindrical counter bore  24  provides a relief for adhesive  25  used to attach the nock adapter  20  to the shaft  12 . The adhesive may be, for example, a two-part epoxy adhesive, a cyanoacrylate adhesive, or the like. The nock adapter  20  may have a length of substantially 1.5 inches and between 1 and 2.5 inches. 
         [0038]    A rear end of the nock adapter  20  provides a rearwardly opening, axially centered cylindrical bore  26  size to receive a corresponding cylindrical boss  28  of a standard nock  30 . The cylindrical bore  26  may have, for example, a diameter of substantially 0.245 inches. The cylindrical boss  28  may provide for a series of radially extending ribs  36  parallel to the axis  17  providing control of the frictional force of engagement and retention of the boss  28  within the bore  26 . 
         [0039]    The nock  30 , per conventional design, may have a rearwardly exposed slot  32  for receipt of a bowstring (not shown). Desirably, the maximum outer circumference  34  of the nock  30  is less than or equal to the outer circumference of the nock adapter  20  and shaft  12  to reduce turbulence and arrow weight. 
         [0040]    Before use, the nock adapter  20  may be attached to the shaft  12  by adhesive which may be allowed to cure. A nock  30  may then be installed on the nock adapter  20  pressing the boss  28  into the bore  26  to be retained therein by frictional contact. In the event that the nock  30  is damaged, it may be pulled from the bore  26  and a new nock replaced in the field without adhesive. 
         [0041]    Desirably, the nock adapter  20  is made of a material that may be adhesively attached to the shaft  12  and which provides for sufficient strength to not be broken under forces that would break the nock  30 . High-strength nylon or aluminum are believed to be suitable for this purpose. 
         [0042]    Referring now to  FIG. 4 , in an alternative embodiment, the nock adapter  20 ′ may provide for a substantially continuous axial bore  26 , for example, conforming to the diameter of the boss  28  of the nock  30  (shown in  FIG. 2 ) and extending the entire length of the nock adapter  20 ′ along axis  17 . Attachment of the arrow shaft  12 ′ to the nock adapter  20 ′ may be accomplished by means of a reduced diameter portion  40  machined on the rear end of the shaft  12 ′ providing a cylinder with a diameter less than the arrow shaft  12 ′ and coaxial with the axis of  17  and extending rearward from the arrow shaft  12 ′ by a distance of  42  approximately one half of the axial length  44  of the nock adapter  20 ′. The diameter of the reduced diameter portion  40  is substantially equal to the diameter of the bore  26  and may be fit within the bore  26  and held by adhesive. The reduced diameter portion  40  produces an arrow shaft  12 ′ that is not compatible with readily available nocks  30 . 
         [0043]    Certain terminology is used herein for purposes of reference only, and thus is not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, and “below” refer to directions in the drawings to which reference is made. Terms such as “left”, “right”, “front”, “back”, “rear”, “bottom” and “side”, describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second” and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context. 
         [0044]    When introducing elements or features of the present disclosure and the exemplary embodiments, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of such elements or features. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements or features other than those specifically noted. It is further to be understood that the method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
         [0045]    Various features of the invention are set forth in the following claims. It should be understood that the invention is not limited in its application to the details of construction and arrangements of the components set forth herein. The invention is capable of other embodiments and of being practiced or carried out in various ways. Variations and modifications of the foregoing are within the scope of the present invention. It also being understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention.