Abstract:
A nock for use with an arrow includes a receiver having a bowstring engaging notch with a pin extending thereacross to capture and retain the bowstring within the notch and an insert permanently attached to an arrow shaft for disengageably engaging the receiver. A retention device, such as a magnet attached to the receiver, magnetically cooperating with a magnetically responsive member attached to the insert, retains the arrow shaft in engagement with the bowstring as the bowstring is pulled back. Upon release of the bowstring, the forward momentum of the arrow overcomes the retention force of the retention device and the arrow shaft disengages from the receiver to begin its flight.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to archery equipment and, more particularly, to nocks for use with arrows. 
     2. Description of Related Art 
     In the field of modem archery, the rear end of an arrow includes a notch for receiving the bowstring. Usually, the notch is defined by a permanently attached nock. The nock includes a hollow end for receiving the end of the arrow shaft. If the shaft is tubular, the nock may include a stud for insertion into the shaft. Other variants for attaching the nock to the shaft exist. 
     The notch of the nock is formed by a pair of rearwardly extending wings for receiving the bowstring therebetween. These wings usually include opposed inwardly extending protrusions for gripping the bowstring as the bowstring is drawn back and released, whether by one&#39;s fingers or by a mechanical triggering element. Generally, the bowstring includes a nocking point formed by dental floss, light thread, or yarn wrapped around the bowstring. Various commercially available sleeves may be attached about the bowstring to serve as a nocking point. 
     Since the bowstring is drawn back by engaging the bowstring itself, not the arrow, there is some danger of the arrow shaft disengaging from the bowstring unless the nock firmly grips the bowstring. Such gripping is provided by the protrusions discussed above. Upon release of the bowstring, the arrow accelerates rapidly in the direction of flight. The resulting momentum of the arrow causes the nock to release from the bowstring at the end of forward travel of the bowstring. The resulting resistance to forward movement of the arrow caused by the arrow overcoming the clamping action of the nock to effect release of the arrow decelerates the arrow to an extent which is a function of the gripping force exerted by the nock. Such deceleration negatively affects the speed of the arrow and hence distance traveled. Moreover, the sudden deceleration may set up a quiver or vibration of the arrow shaft along its length which affects its aerodynamic properties, and increases air resistance. The vibrating arrow shaft may also affect the accuracy of its expected trajectory. By reducing the clamping force of the nock, inadvertent disengagement of the nock from the bowstring is to be expected under field conditions. Such disengagement is unacceptable in a hunting environment. This result may even cause a life-threatening situation if the animal being hunted is prone to attack the archer. 
     SUMMARY OF THE INVENTION 
     The present invention is a two-part nock having an insert permanently attached to the rear end of the shaft of an arrow and a receiver retained by a bowstring and disengageably engageable with the insert. The receiver includes a notch for receiving the bowstring and a pin extending across the notch for precluding disengagement of the bowstring from the notch. A cavity in the receiver slidably receives the insert in a predetermined aligned manner to ensure proper orientation of the fletching or feathers of the arrow. The insert is retained with the receiver by use of a magnet, hook and loop fastening means, or other disengageable engaging means. The retention force between the insert and the receiver is sufficient to preclude disengagement of the arrow as the bowstring is pulled back under field conditions and yet the force required to release the arrow at the end of travel of the bowstring is minimal and has little negative effect upon the flight path of the arrow. 
     It is therefore a primary object of the present invention to provide a two-part nock for easily disengaging an arrow from a bowstring. 
     Another object of the present invention is to provide a two-part nock having a receiver retained on a bowstring and a shaft mounted insert disengageably engageable with the receiver. 
     Still another object of the present invention is to provide a two-part nock using a magnetic force to retain the parts engaged and yet permit disengagement. 
     Yet another object of the present invention is to provide a nock attached to a bowstring for disengageably engaging the end of the shaft of an arrow in predetermined alignment. 
     A further object of the present invention is to provide a nock attached to a bowstring at a predetermined location for engaging the end of an arrow shaft in predetermined alignment. 
     A still further object of the present invention is to provide a nock having an insert permanently attached to the end of an arrow shaft for disengageable engagement with a receiver secured to a bowstring. 
     A yet further object of the present invention is to provide a method for releasably securing an arrow shaft with a nock attached to a bowstring. 
     These and other objects of the present invention will become apparent to those skilled in the art as the description thereof proceeds. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be described with greater specificity and clarity with reference to the following drawings, in which: 
     FIG. 1 illustrates an assembled two-part nock and a partial view of a bow and arrow; 
     FIG. 2 illustrates the insert and receiver of a two-part nock; 
     FIG. 3 illustrates a partial view of the bowstring retention element of the receiver; 
     FIG. 4 illustrates a magnet for disengageably engaging the insert with the receiver; 
     FIG. 5 is an end view from the front of the nock taken along lines  5 — 5 , as shown in FIG. 1; 
     FIG. 6 is an end view from the rear of the nock taken along lines  6 — 6 , as shown in FIG. 1; and 
     FIG. 7 illustrates a further variant construction of the insert to engage a further type of arrow shaft. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring jointly to FIGS. 1 and 2, there is shown a two-part nock  10  having an insert  12  and a receiver  14 . Reduced diameter stud  16  of insert  12  fits within and is secured to the rear end of hollow shaft  18  of an arrow  20 . The attachment between the stud and the shaft may be secured by use of an adhesive, press fit, or the like, for a permanent engagement. A base  22  of insert  12  slidably fits within a sleeve  24  of receiver  12 . A notch  26  is formed in receiver  14  by a pair of wings  28 , 30 . A bowstring  32  is seated within notch  26  and is prevented from disengagement with receiver  14  of nock  10  by a pin  34  secured in wings  28 , 30  and extending across the notch. Axial orientation of arrow  20  relative to the bow and bowstring is important to ensure that the fletchings, or feathers, of the arrow are correctly oriented with respect to the bow and with respect to any attachments to the bow in proximity of the arrow as the arrow is discharged therepast. Such orientation is achieved by ridge  36  extending radially from insert  12  into engagement with a slot  38  formed in sleeve  24  of receiver  14 . 
     Referring jointly to FIGS. 2,  3 , and  4 , further details of nock  10  will be described. Sleeve  24  of receiver  14  includes a cylindrical cavity  40  for receiving base  22  of insert  12 . The end of the base includes an iron, steel, or other magnetically responsive plate  42 . As shown in the partial cutaway view in FIG. 4 of sleeve  24 , a magnet  44  is disposed at the end of cylindrical cavity  40  in receiver  14 . Upon insertion of base  22  into the cylindrical cavity, the force of magnet  44  acting upon plate  42  will retain insert  12  in engagement with receiver  14 . Upon exertion of an axially oriented force upon insert  12  away from receiver  14 , such as the momentum of the arrow leaving the bowstring, the magnetic force between magnet  44  and plate  42  will be overcome and separation between the insert and the receiver of the nock will occur. It is to be understood that the locations of the magnet and plate may be reversed and that other disengageable/engageable means such as a pair of magnets to increase the magnetic force, the hook and loop type fastener sold under the trademark Velcro™, a reuseable mastic, ball and releaseable socket, or other chemical or mechanical elements permitting engagement and disengagement upon application of appropriate forces, are also useable. 
     To assist bringing about engagement of the insert with the receiver to secure an arrow to the bowstring, entrance to slot  38  may be chamferred by chamfers  50 , 52  to guide ridge  36  into the slot. Similarly, proximal end  54  of ridge  36  may be tapered or rounded (as shown) to facilitate insertion of the ridge into slot  38 . 
     Retaining pin  34  discussed with respect to FIG. 1 is shown in further detail in FIG.  3 . While pin  34  may be removable to permit insertion of bowstring  32  into notch  26 , such removal should be only on an occasional basis. Receiver  14  is intended to remain affixed to the bowstring during a hunting or other archery related event. It is therefore contemplated that the pin may be a press fit into corresponding aperture  56  of wing  28  and aperture  58  of wing  30 . By using a press fit, the pin is removable when necessary and yet will be retained in place during normal use of the bow. Other retention means, such as a threaded engagement, can be used. 
     Referring particularly to FIG. 4, there is shown a variant configuration of insert  12 . In this variant, a cylindrical cavity  60  for receiving a necked down section of an arrow shaft is used instead of stud  16 . Alternatively, if ridge  62 , defining the cavity, will not interfere with the bow or arrow support/guidance devices on the bow, the end of the shaft, without a necked down section, may be directly lodged within cylindrical cavity  60 . Thus, the variant of insert  12  shown in FIG. 4 is primarily for use with solid, not tubular, arrow shafts. 
     Referring jointly to FIGS. 5 and 6, the respective end views of nock  10  will be described. As shown in FIG. 5, stud  16  is of a diameter reduced from that of insert  12  to accommodate for the wall thickness of an hollow arrow shaft disposed thereabout. Thereby, an essentially smooth cylindrical surface is presented at the junction of the arrow shaft and the insert to preclude interfering contact with the bow or elements thereof as the arrow assumes its flight path. Ridge  36 , extending radially from the insert, is oriented with respect to the fletchings on the arrow shaft and the bow and its attachments to preclude interference therebetween as the arrow begins its travel past the bow. To prevent any possible interference between ridge  36  and the bow with its attachments, it is to be understood that a ridge may extend radially inwardly from sleeve  24  of receiver  14  for mating with a commensurately formed groove or slot in insert  12 . 
     Receiver  14 , as shown in FIG. 6, may include a tapered section  70  to reduce the diameter present at wings  28 , 30 . The inside surfaces of wings  38 , 30  may include opposed inwardly extending protrusions  72 , 74  for engaging and being retained at the nocking point on the bowstring. With or without these protrusions the proximal ends of the wings may be outwardly tapered or curved proximally of the protrusions, as depicted by sections  76 , 78 . Forwardly thereof, notch  26  may increase in width and thereafter close in a curved manner. Pin  34  may be flush with the outer surface of the wings or it may protrude slightly from each wing, as illustrated. If one end of the pin protrudes a sufficient length, it may be gripped to remove the pin for insertion of the bowstring into the notch. If the ends of the pin are flush, the pin may be pushed toward one wing and thereafter withdrawn. Insertion of the pin into the wings after the bowstring has been placed in the notch is self-evident. 
     FIG. 7 discloses a variant of insert  12  having a distal end  80  particularly suited for engaging and supporting an hollow arrow shaft. The distal end includes an external cylinder  82  and a stud  84  disposed therewithin to define an annular space  86  equivalent in width to the wall thickness of the arrow shaft. With the construction shown in FIG. 7, a very robust attachment mechanism between the arrow shaft and the insert is achieved. The fit therebetween may be a press fit, an adhesive may be used or other techniques may be used to secure insert  12  to the arrow shaft. 
     While the invention has been described with reference to several particular embodiments thereof, those skilled in the art will be able to make the various modifications to the described embodiments of the invention without departing from the true spirit and scope of the invention. It is intended that all combinations of elements and steps which perform substantially the same function in substantially the same way to achieve the same result are within the scope of the invention.