Abstract:
A foldable archery bow has a center section and two flexible arms extending in substantially opposite directions, describing a bow plane, and a separation interface disposed in the center section and positioned to allow the bow to be separated into two separate sections. At least one latching connector is attached to a first point on one of the flexible arms, and is adapted, when the flexible arm to which it is attached is substantially flexed, to latch at a second point on the same side of the separation interface as the first point. By drawing the bow, which flexes the flexible arms, and latching the latching connector, all tension is released from the bow string or strings, and all forces thereby removed from the separation interface. The separation interface, normally fastened in a closed position, may then be unfastened and separated, allowing the bow to divide into the two separate sections forming a smaller package than in the assembled aspect. The bow may be again set up by aligning and refastening the separation interface, drawing the bow, and unlatching the connector, restoring the same tension to the bow that it had before folding. In some embodiments a hinge is employed at the separation interface, allowing the bow to fold, and a variety of force removal mechanisms are taught.

Description:
This application is a continuation-in-part of U.S. Pat. application Ser. No. 09/096,859 filed Jun. 12, 1998 and entitled “De-Tensioning and Breakdown System for a Compound Bow”. 
    
    
     FIELD OF THE INVENTION 
     The present invention is in the field of archery and has particular application to methods and apparatus for de-tensioning and breaking down a compound bow for such as storage and travel. 
     BACKGROUND OF THE INVENTION 
     Bow-hunting and archery target shooting are human occupations with a long history. Accordingly the technical form of bows and other archery equipment has gone through countless design and functional improvements over time from ancient age to the present day. There are many differing designs for bows. For example, single-piece long bows, typically as tall or taller than the shooter were used by Native Americans for hunting. 
     Later in history, laminated bows and cross-bows (a bow mounted on a triggered gun stock) were introduced, and opposing-curve bows were developed providing more power than their predecessors. Bow strength was greatly increased via lamination techniques and the opposing curve design, termed in the art a recurve design. This landmark improvement allowed the length of the bow to decrease while retaining maximum power or pull. 
     More recently, an innovation known as the compound bow revolutionized the institution of archery, particularly bow hunting. The compound bow is typically a tri-sectioned (two arms and a center section) bow combined with a pulley and cabling system. Designed in important instances for hunting, the compound bow is more powerful than a traditional curve bow but demands less stamina and strength from the user. Once the bowstring of a compound bow is drawn back to a prescribed distance, bow tension is significantly reduced allowing the shooter to relax before letting the arrow fly to target. This is accomplished via action of the pulley/cable system which acts to compound the power of the bow while at the same time reducing the pull strength required to let loose an arrow. The compound bow is arguably the most popular type of bow in use today. 
     One problem with a compound bow, however, is that it must be tuned or balanced before accurate shooting can be performed. That is, the tension on the upper arm of the bow must equal the tension on the lower arm of the bow in order for an arrow to fly accurately. To insure that proper balancing of tension is accomplished, one must shoot an arrow to see if it is on target. Tension adjusting devices are employed to equalize tension after the bow is strung. Adjustment and sighting-in is typically necessary each time a bow is unstrung and then strung again. These adjustments can be time-consuming especially for a novice. 
     Another problem stems from the fact that it is desired to be able to transport a bow and related accessories conveniently and compactly when the bow is not in use. Often, the size of a compound bow inconveniences the user in this regard. The bow is generally of an awkward shape, taking up significant space in transport. Some bow manufacturers have attempted to alleviate this problem by developing a hinged bow that may be folded over when not in use. However, the bow must first be unstrung, or the tension on the bow somehow released before the bow may be folded, because the tensioned bow imposes significant forces on the hinge in the bow stock, and once set up again, the bow must also be re-tensioned (compound bow) and re-sighted before it will shoot with accuracy. 
     What is clearly needed is a de-tensioning and breakdown system that will allow a compound bow to be broken-down to smaller components or sections and stowed without requiring re-tensioning, re-tuning, and re-aiming of the bow to its previous operational state. 
     SUMMARY OF THE INVENTION 
     In a preferred embodiment of the present invention a break-down bow is provided, comprising a center section, a first flexible arm extending from the center section in a first direction; a second flexible arm extending from the center section in a direction substantially opposite the first direction, the first and second flexible arms and the center section substantially describing a bow plane; a separation interface in the center section having a fastening mechanism adapted as fastened to retain the bow in a usable aspect, and as unfastened to allow the bow to separate at the separation interface into the two separate sections; and a first connector mechanism adapted to connect between a first point on or attached to the first flexible arm away from the center section and to a second point on the same side of the separation interface as the first point, and adapted to be selectively engaged by a user with the first flexible arm sufficiently flexed to remove all forces from the separation interface in the center section, the first connector mechanism, engaged, then retaining the first flexible arm in the flexed position such that the separation interface may be released and the bow folded. 
     In one embodiment the first point and the second point are both on or attached to the first flexible arm, and the second point is on the center section. In preferred embodiments the first connector mechanism is a first link pivoted at the first point and adapted to latch at the second point with the first flexible arm flexed to a sufficient degree to release all force on the separation interface in the center section. The latching may be by a male-and-female latching mechanism provided at the second point. In some cases the link is pivoted by a quick-release pivot mechanism wherein, with the link unlatched, the link may be removed from the bow entirely by disengaging the quick-release pivot mechanism. 
     In an alternative embodiment the first connector mechanism is adapted to be engaged with the first flexible arm flexed sufficiently to remove a first portion of forces imposed on the separation interface, and there is a second connector mechanism adapted to connect between a third point on or attached to the second flexible arm away from the center section and to a fourth point on the same side of the separation interface as the third point, and adapted to be selectively engaged by a user with the second flexible arm partly flexed to remove a second portion forces imposed on the separation interface, such that the first portion of forces and the second portion of forces together equal at least the magnitude of forces on the separation interface, the first and second connector mechanisms, engaged, then retaining the flexible arms in flexed positions such that the separation interface may be released and the bow separated into the two separate sections. 
     In one manifestation of this alternative the first point and the second point are both on or attached to the first flexible arm, and the third point and the fourth point are both on or attached to the second flexible arm. In another the first point is on or attached to the first flexible arm, the second point is on the center section on the same side of the separation interface as the first point, the third point is on or attached to the second flexible arm, and the fourth point is on the center section on the same side of the separation interface as the third point. 
     The bow with two connector links is set up to provide a portion of tension release by one mechanism and another portion by the other mechanism. The links may latch by male-female latching devices. Also in preferred embodiments, whether one link or more is used, the links may be removed when not in use, if desired, by virtue of quick-release pivot points. In yet another preferred embodiment the separation interface incorporates a hinge, whereby the two separate sections may remain connected when the bow is broken down, and be folded over around the hinge. 
     In another embodiment of the present invention, the break-down bow includes upper and lower bow limbs each of which consists of a pair of spaced, side-by-side limb elements, such as the spaced side-by-side limb elements disclosed in U.S. Pat. No. 5,720,267, “Archery Bow With Limb Mounting Pockets”. In this embodiment, the connection mechanism which is the same for both the upper and lower bow limbs, comprises at one end a spaced, side-by-side recurve limb strap which fits over and engages side-by-side limb elements at the limb tips. The other end of the connector mechanism includes a hook for engaging a post on the riser handle. The connector mechanism provides a pivot enabling the recurve limb strap to pivot with respect to the hook and a threaded connecting rod for enabling the distance between the limb strap and hook to be varied. A clamping assembly secures the limb strap to the limb elements. 
     In addition to unique apparatus to provide the objects of the invention, methods for practicing the invention are taught as well. The invention is particularly adapted and suited to compound bows, the favorite of most bow hunters, and provides, for the first time, a way to break down such a bow for travel and storage, and to set up the bow again to its exact former tension without having to readjust or resight the bow. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     FIG. 1 is a side view of a compound bow equipped with bowstring de-tensioning and bow breakdown apparatus according to an embodiment of the present invention. 
     FIG. 2 is a rear view of the compound bow of FIG.  1 . 
     FIG. 3 is a rear view of the compound bow of FIG. 1 shown with the bowstring de-tensioned and the bow partly folded according to an embodiment of the present invention. 
     FIG. 4 is an expanded view of a latching link and pivot components according to an embodiment of the present invention. 
     FIG. 5 is an enlarged view of a bow hinge of the bow of FIGS. 1-3. 
     FIG. 6 is a partial side view of another embodiment of the connector mechanism of the present invention. 
     FIG. 7 is a complete side view of the connector mechanism shown in FIG. 6 in which the elements comprising the connector mechanism are disassembled. 
     FIG. 8 is a perspective view of a bow including the connector mechanism shown in FIG.  7 . 
     FIG. 9 is a partial view of the connector mechanism shown in FIG.  6 . 
     FIG. 10 is an elevational view of the clamp used in the embodiment of the connector mechanism shown in FIG.  6 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a side elevation view of a compound bow equipped with tension cancellation and bow-breakdown apparatus according to an embodiment of the present invention. A compound bow  11  is provided according to an embodiment of the present invention, which allows a bowstring  41  of bow  11  to be de-tensioned so that bow  11  may then be folded over and stowed for easy porting. A principal object of the present invention is to provide for quick breakdown and re-assembly of bow  11  after such bowstring de-tensioning and bow breakdown without requiring for re-adjustment and re-aiming. 
     Bow  11  may be any compound-style bow, but it is emphasized that the system of the invention in other embodiments is also useful for bows of all sorts. In the case of compound bows there are typically three basic sections. A solid center section  17  which is a riser acts as a support for flexible bow arms  13 , and  15 , and for mounting other elements, such as aiming apparatus. The flexible arms provide the string tension and the power for the bow. Center section  17  may be manufactured from aluminum, wood, or from any of several other materials common to bow manufacture. Bow arms  13  and  15  may be made from wood or from any of several polymer materials, or from other materials such as carbon fiber. Bow arms  13  and  15  are, in this embodiment, fixedly attached to center section  17 . However, they may also be mounted using other means such as pivotal lock-mounting, bolting, or other methods that may be convenient for a particular style or model of a bow. 
     Center section  17  in a preferred embodiment has a separation interface, such as a hinge, that allows bow  11  to be separated into two sections. In the embodiment used herein, the separation interface is hinged, so the two sections of the bow remain connected, although the bow, when broken down, becomes folded in a direction substantially perpendicular from the flat plane of bow  11 , which may be considered to be the plane of the paper in FIG.  1 . In this embodiment, hinge  19  is substantially centered longitudinally on center section  17 , although the exact position of the hinge or other separation interface is not critical. The direction of fold may be either direction, and, depending on the mounting of peripheral apparatus in particular bows, one direction may be preferable over the other. 
     Hinge  19  or a separation interface without a hinge may be secured (locked) via any of several known methods. In this embodiment, hinge  19  or other interface is secured by screw fasteners when bow  11  is in use. In another embodiment, the interface may be clamped, or perhaps locked with a quick-release-type locking mechanism. 
     In the case of a compound bow, pulley mechanisms such as pulleys  29  and  31  pivotally attached to upper bow-arm  13 , and pulley  33  pivotally shown attached to lower bow-arm  15 , are for providing mechanical advantage in a compound bow. Other sorts of bows to which the invention may be applied do not have these mechanisms. In any case, such mechanisms are well-known in the art, and not critical to the invention. Other mechanisms not shown but common to compound bows as accessories or attachments may be assumed to be present such as bow tension adjustment devices, arrow rests, aiming sights, and so on. The method and apparatus of the present invention may be applied to substantially any sort of compound bow. 
     Referring again to FIG. 1, and assuming bow  11  to be set up, aimed in, and ready for use, to break down the bow it is necessary to remove the forces imposed on the hinge as a result of the tension in the string and pulley apparatus. To accomplish releasing the tension there are two unique latching links, link  21  and link  23 , that act, when engaged, to hold arms  13  and  15  in a flexed position independent of one another, removing tension on the string and pulley apparatus, and therefore also on center section  17  and its hinge. Links  21  and  23  are pivotally attached to bow arms  13  and  15  such that each may rotate substantially in the flat plane of the bow. A mounting clamp  37  is provided and mounted to bow arm  13  in order to support pivotal mounting apparatus for link  23 . A similar mounting clamp  35  is similarly provided and mounted to bow arm  15  in order to effect the same purpose relative to link  21 . 
     Link  23 , pivoted at one end, has a latching mechanism at the opposite end  25  adapted to latch to an appropriate on center section  17 , when arm  13  is partially and substantially flexed. Similarly, link  21  has a free end  27  with the same mechanism and serving the same purpose for flexible arm  15 . Links  23  and  21  in a preferred embodiment are removable after use and may be detached from their pivotal positions at clamps  37  and  35  via quick-release pivot mounts (not shown in FIG.  1 ). Such quick-release pivot mounts are known in the art and are described in more detail below. 
     FIG. 2 is a rear view of the compound bow of FIG.  1 . Ends  25  and  27  in this embodiment each have a hole  36  adapted to engage a pin  38  at each one of two contact locations  24  and  28  on center section  17 . The length of each of links  21  and  23  from the pivot to the circular opening at the opposite end is such that the pin and opening will not line up to engage unless the bow is sufficiently drawn, resulting in sufficient bending of the flexible arms of the bow. The position of the latching mechanism is such that if latched in the bow&#39;s drawn position, all tension on the stings and separation interface, in this case a hinge, will be released. One sets the latches by aiming the bow downward and drawing the bow until the pins on center-section  17  engage the holes in the links. The links in this bow position naturally pivot downward, so when the pins and holes align, they engage. When one releases the bow, each of the flexible arms  13  and  15  remain independently flexed, and tension is removed from hinge  19 . Rubber bands  36  and  38  may be utilized to secure bowstring  41  in place around the respective pulleys  29 ,  31  and  33 . 
     When one sets up a bow, the links may be released by pointing the bow upward and drawing the bow. Gravity in this position causes the links to rotate away from center section  17 , and the pins and holes disengage when the bow is sufficiently drawn. 
     The skilled artisan will be aware that pins and holes are but one of several latching arrangements that might be made. In another embodiment, for example, a hook instead of a pin may be provided on center section  17  with the hook adapted to catching a horizontally mounted pin on a pivotal link. Other types of groove and catch mechanisms may be used as well. One with ordinary skill will recognize that a number of known male-female mechanisms will suffice for the purpose. 
     FIG. 3 is a rear view of the compound bow of FIG. 1 shown with the bowstring de-tensioned by latching the links with the flexible arms partially flexed, and with the bow partly folded over the hinge. 
     Hinge  19  is held closed in a preferred embodiment by conventional fasteners such as socket-head screws, as is described further below with aid of FIG. 5. A separation interface without a hinge in an alternative embodiment is held closed in the same manner. In the breakdown operation the user de-tensions the bow as described above, then unbolts the hinge and folds the bow around the hinge. Once folded the bow may be conveniently carried as a smaller, less clumsy package, or may be placed in a special carrying case designed to accommodate the folded bow. 
     To re-assemble bow  11  for operation, a user simply closes hinge  19  and bolts it closed, thereby returning bow  11  to its original upright position. Once this is accomplished and hinge  19  is secure, a user points bow  11  skyward, as briefly described above, while drawing back bowstring  41  with sufficient force required to release links  21  and  23  from their latched condition. Links  23  and  21  may then swing about their pivot mounts toward the user. Bowstring  41  is then released, returning the bow to its ready-to-shoot condition and links  23  and  21  may be detached from their pivotal mounts and stowed. Bow  11  is then ready to use. It is important to note, as well, that the bow is restored in a single swift motion to exactly the tension that it had when de-tensioned for folding, and therefore no adjustment or re-aiming is needed. 
     In an alternate embodiment, links  23  and  21  may be adapted to swing in a plane perpendicular from the plane of the bow. In that case the position of holding the bow to latch or de-latch catch-ends  25  and  27  would be changed according to the alternate direction of swing. For example, holding the bow horizontally while drawing the bowstring for enabling the latches, and then flipping the bow over in the same position for releasing the latches. While this embodiment is possible, it is preferred that links  23  and  21  swing in the plane of the bow as previously described above. 
     In an alternate embodiment, the method and apparatus of the present invention may be practiced on a conventional re-curve style bow simply as a means to de-tension the bowstring for easy replacement as previously described. 
     In the embodiment shown in FIGS. 6 through 10, there is shown a connector mechanism  58  including a spaced side-by-side recurve limb strap  60  which fits over and engages spaced side-by-side limb elements  62  at the limb tips, or outer end, of limb  63 . The connector mechanism  58  shown in FIGS. 6 through 10 fits over and engages bottom limb elements  62 . An identical connector mechanism (not shown) fits over and engages top identical spaced side-by-side limb elements. 
     With particular reference to FIG. 7, it is seen that recurve limb strap  60  includes a lug  64  having a hole  66  therein. A pivot  68  includes a hole  70  of the same size as hole  66  in lug  64 . A pin (not shown) extends through holes  66  for pivotally connecting the limb strap  60  and pivot  68 . One end of a threaded rod  72  is screwed into hexagonal nut  74  and into a threaded opening in the rear portion of pivot  68 . When the end of threaded rod  72  is screwed into the rear portion of pivot  68  the desired distance, hexagonal nut  74  is screwed around threaded rod  72  until hexagonal nut  74  abuts the rear surface of pivot  68  to firmly maintain threaded rod  72  within the threaded opening in the rear portion of pivot  68 . The desired distance as used herein and below, is the distance required to maintain the bow in its flexed position so that the tension on the strings and separation interface is released. 
     The other end of threaded rod  72  is screwed into hexagonal nut  76  and into a threaded opening in the rear portion of hook  78 . When the end of threaded rod  72  is screwed into the rear portion of hook  78  the desired distance, hexagonal nut  76  is screwed around rod  72  until hexagonal nut  76  abuts the rear surface of hook  78  to firmly maintain threaded rod  72  within the threaded opening in the rear portion of pivot  68 . A post  80  in center section  82  is engaged by hook  78  for connecting the threaded rod  72  and recurve limb strap  60  with center section  82 . 
     Center section  82  functions in the same manner as center section  17  of FIG. 1, although it is of slightly different aesthetic configuration. Thus center section  82  has a hinged separation interface  84  that allows the bow to be separated into two sections. When the separation interface  84  is hinged, the two sections of the bow remain connected. When the separation interface  84  is unhinged, the bow is folded in a direction substantially perpendicular from the flat plane of the bow. As with the embodiment illustrated in FIG. 1, the direction of fold may be in either direction. 
     A clamping assembly  86  secures connector mechanism  58  to the side-by-side limb elements  62 . Clamping assembly  86  includes a knob assembly  88  having a threaded portion  90  which extends through opening  91  in recurve limb strap  60  and then between side-by-side limb elements  62 . Threaded portion  90  is screwed into opening  92  in clamp  94  (see FIG. 10) to secure connector mechanism  58  to side-by-side limb elements  62 . Rubber band  95  may be utilized to secure the bowstring in place around the respective pulley when the tension is removed from the hinge separation interface  84 . 
     FIG. 4 is an enlarged view of link and pivot components according to an embodiment of the present invention. A suitable quick-release method for pivotal mounting of latching links to bow arms is provided and is also well known in the art. Mount  37  is shown mounted on upper bow arm  13  of FIG.  1 . Returning to FIG. 4, a quick-release socket  43  comprises a circular bore  44  and a groove  42  radially around the inside diameter of the circular bore. A quick-release shaft  45  has an outside diameter smaller than the inside diameter of bore  44  and a spring-loaded ball  46  adapted to engage groove  42 . A quick-release pin  47  is adapted to release the pin-and-groove engagement to release a pivot for removal. 
     FIG. 5 is an enlarged view of bow hinge  19  of FIG.  3 . Hinge  19  is a typical pinned-hinge comprising a hardened steel pin  49  and hinge-plates  53 , and  55 . Both hinge plates  53  and  55  contain bolt holes  51  placed to facilitate bolting hinge  19  to a closed position. Bolt holes  51  are accessible via cut away areas (not shown) in center section  17  from the pin-side of hinge  19  both above and below hinge  19 . In an alternative embodiment a hinge is not used, but the joining plates with matching holes may be as seen in FIG.  5 . 
     There are a variety of ways to present hinge  19  without departing from the spirit and scope of the present invention. For example, center section  17  (actually two separate pieces) may be bolted on to hinge plates  55  and  55 . In another embodiment, center section  17  may be provided with hinge elements  19  incorporated into the construction such that each side of hinge  19  is of the same material and of one piece with each section-half to be hinged. In this case bolting may be accomplished in the same fashion. 
     It will be apparent to one with skill in the art that various styles of compound bows will have center sections of differing constructions and shapes. Therefore, the exact configuration of hinge  19 , in those embodiments having a hinge, and bolting arrangement may vary accordingly. 
     It will also be apparent to the skilled artisan, after reading the present teaching, that it is not necessary to flex and latch both flexible arms of a compound bow to remove all forces imposed by the bow on a hinge in the center section. A single link acting to latch either one of the flexible arms flexed to a suitable degree will suffice to remove forces from the hinge and allow the bow to fold. Accordingly, in some alternative embodiments only one such link is provided. It will be apparent, too, that the latching mechanism can also attach to two divergent points on the same flexible arm. It will also be apparent that swinging and latching links are not the only apparatus that may be used to accomplish the purpose. One might connect a position away from the center section on a flexible arm of such a bow with the center section by any of several devices, such as a cable arrangement with a turn-buckle, a fold-over latch with cable ends as are known in the art, and by other ways as well. It is desirable that the mechanism used allow quick and simple, as well as safe operation. 
     It will also be apparent to one with skill in the art that hinge  19  may be provided with a locking means other than conventional fasteners without departing from the spirit and scope of the present invention. For example, in one embodiment, a unshaped sliding lock piece may be adapted to engage slots in hinge-plates  53  and  55  thus locking them closed. In another embodiment, external clamps may replace bolts, and so on. In embodiments without a hinge there are similar variations in the manner in which the opposing parts of the separation interface may be fastened. 
     Two desirable attributes for hinge  19  are that opening occurs in a direction substantially perpendicular to the plane of the bow, and that sufficient locking force is used when locking hinge  19  in a closed position. 
     It will be apparent to one with skill in the art that the apparatus of the invention comprising links, pivot mounts and the like, including a hinge such as hinge  19 , may be manufactured into a new compound bow, or into an existing compound bow to be modified. It will also be apparent, as described above, that a wide variety of separation interfaces may be used without a hinge. The method and apparatus of the present invention is limited only by the claims that follow.