Abstract:
An archery bow having a riser, a pair of flexible limbs extending from the riser, with each limb having a rotating member on an axel secured to the end thereof. At least one of the rotating members is a cam having a module secured thereto. The module is positionable with respect to the cam by translational movement and is also positionable on the cam with an opposite face against the cam to selectively provide a desired draw length.

Description:
RELATED APPLICATIONS 
   The present application claims priority to a provisional application filed Sep. 28, 2006 under Ser. No. 60/827,311 entitled “REVERSIBLE AND ADJUSTABLE MODULE SYSTEM FOR ARCHERY BOW”. 

   FIELD OF THE INVENTION 
   The present invention pertains to archery bows and more particularly to archery bows having modules attachable to cams for adjusting draw weight and draw length. 
   BACKGROUND OF THE INVENTION 
   Archery bows must be customized to fit each specific archer; particularly, each archer has a unique desired draw length and is usually limited to a particular maximum draw weight. Manufacturers and dealers of archery bows thus must produce a variety of bows each having a particular draw weight or draw length so that the archery bow is properly matched to the individual archer. Draw length and draw weight can be changed by archery dealers but such changes are usually limited and require dedicated equipment to accomplish the modifications. Further, such modifications are time consuming and require skill to properly make changes to the draw weight and draw length to fit a particular archer. 
   SUMMARY OF THE INVENTION 
   The present invention incorporates the utilization of modules that are attachable to the cams of a compound bow. In the example chosen for illustration, the bow is a dual cam bow; however, the same concept is applicable to a one cam bow. The modules are attachable to the faces or surfaces of a cam and are positionable by translational movement. The modules provide a groove for contacting the cable or cables of the archery bow and include dual profiles along the periphery of the module to permit the module to be reversed or “flipped” to permit the engagement of an opposite surface of the module with the mounting surface of the cam. In the “flipped” position, a different peripheral portion of the cable-engaging groove is presented to the cable during draw. The peripheral profiles of each portion is different with respect to each other such that a draw length provided by one sector on the periphery of the module is different than the draw length provided by the second peripheral sector of the module when the module has been flipped. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side elevational view of a dual cam bow incorporating the teachings of the present invention. 
       FIG. 2  is an isometric view of the lower cam portion of the bow of  FIG. 1 . 
       FIG. 3A  is an isometric view of an opposite side of the cam shown in  FIG. 2 . 
       FIG. 3B  is an end view of the cam and module shown in  FIG. 2 . 
       FIGS. 4A ,  4 B and  4 C are successive illustrations of the positioning of the module of the present invention in respective positions on the cam of the bow of  FIG. 1  showing the positioning of the module for different draw weights. 
       FIGS. 5A and 5B  are views of a module constructed in accordance with the teachings of the present invention showing the first and second surfaces for contact with a cam and showing an elongated guide slot. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIG. 1 , a two cam bow  10  is shown incorporating a riser  12  that includes a grip  14  formed therein. The riser supports a pair of flexible limbs  15  extending therefrom; the limbs are secured to the riser through limb screw bolts  17 . The respective ends of the limbs  15  support axels  19  mounted on the respective limbs and support a pair of cams  20  mounted thereon for rotation about the respective axel. A bowstring  25  extends between the upper and lower cams; a cable  28  extends from the upper cam  20  to the lower limb  15 . A cable  29  extends from the lower cam  20  to the upper limb  15 . A cable guard  31  is mounted on the riser  12  and extends toward the bowstring  25  and supports a cable guard slide  32  which engages the cables  28  and  29  to position the cables out of the plane of motion of the bowstring during draw and bowstring release. 
   Referring to  FIG. 2 , an enlarged isometric view of the lower cam of  FIG. 1  is shown. The cam  20  is shown having a cable post  35  to which the cable  29  is secured. The cam  20  includes a bowstring engaging peripheral groove  21  and a flat surface  22  for contacting the module  40 . The module may be secured to the surface  22  of the cam  20  through conventional means such as screws  26 . The cam is mounted for rotation about axel  19  which is mounted to the flexible limb  15 . The cable  28  is shown secured to the limb  15  through the axel  19 . A module  40  is shown secured to the cam  20  such as by screw fasteners  26  extending through the module and threadedly engaging threaded holes  27  provided in the cam ( FIG. 3A ). The module is positioned so that as the bowstring  25  is drawn, the cam  20  rotates imparting rotational movement to the module  40  and causing a peripheral sector  42  to engage the cable  29 . From brace height (essentially the position of the bow system as shown in  FIG. 1 ) to a full drawn position, the peripheral sector  42  will continuously contact the cable  29  as the cam  20  and module rotate through an angle alpha as shown in  FIG. 2  to establish a predetermined draw length. A second peripheral sector  48  will not contact the cable  29  during the draw and will have no effect on draw length. The draw length is thus determined by the configuration of peripheral sector  42  of the module  40 . 
   In  FIG. 2 , the module  40  is shown secured to the cam  20  with a first surface in contact with the flat cam surface  22 . In this position, the peripheral sector  42  contacts the cable  28  as the cam is rotated and thus determines the draw length. If the module  40  were reversed or “flipped” such that an opposite surface of the module  40  contacts the cam flat surface  22 , the second peripheral sector  48  is in position to contact the cable  29  as the cam is rotated, the draw length would then be determined by the second peripheral sector  48 . 
   The module is formed having parallel opposing flat surfaces  50  and  51  ( FIGS. 5A ,  5 B) separated to define a peripheral cable-engaging groove  60  therebetween. As indicated above, the groove  60  has a first peripheral segment  42  and a second peripheral segment  48 . The module includes an elongated guide slot  56  that engages a cam guide member  59  that may be formed integrally with and extend upwardly from the cam surface  22 . Holes  24  are provided in the module  40  to admit screw fasteners  26  therethrough for engagement with threaded holes  27  in the cam  20 . The holes  24  may be arranged in groups and are countersunk  23  to accept metal washers for engaging the screw fasteners as they pass through the module to engage the cam. 
   Draw length adjustment using modules such as module  40  is accomplished by changing the amount the cam  20  rotates before reaching a stop position at full draw. Typical cam rotation during draw is in the range of 140° to 220° from brace height to full draw. The reversible module  40  relies upon cam rotation that is a fixed amount less than or greater than 180° and which rotation can be combined into a single module  40 . For example, module  40  can be configured to create two distinct draw lengths depending on which flat surface of the module is placed in contact with the corresponding flat surface of the cam. For example  FIGS. 5A and 5B  illustrate a single module that may be affixed to a corresponding cam with either first surface  50  or second surface  51  in contact with the flat surface of the cam. 
   Bow limbs act as energy storage springs and are governed by the basic linear spring equation F=kx (where F=Force, k=spring constant and x=spring deflection). The draw force on the bowstring is directly related to the forces generated by the bow limbs and the mechanical advantage provided by the cam at each rotational position. Bow draw weight changes may be made by adjusting the effective spring constant (k) of the limb to change the draw force (F). Minor adjustments may be made by turning the limb screw bolt  17  in or out, although such adjustments must be limited to prevent accidental dislodgement of the bolt if backed out too far. Adjusting module position acts to increase or decrease both the limb force and the leverage in the draw cycle. At the same time the limb movement is increased or decreased, the mechanical advantage of the cam is inversely decreased or increased. The combination of increased limb movement with decreased leverage changes the effective peak draw weight. Referring to  FIGS. 4A through 4C , the module  40  is shown in three separate attachment positions affixed to the cam  20 . The cam  20  includes a cam guide member  59  that is integrally formed with the cam, and which extends into an elongated guide slot  56  provided in the module  40 . 
   This interrelationship of the guide slot and guide permits sliding translational movement of the modules over the cam surface. It may be noted that the module does not change its angular position with respect to the cam  20  but merely translates by movement along the slot  56 . This translational movement provides insurance against rotational relative movement between the module and the cam and also assists the archer in selecting the appropriate position of the module. Further, the interaction of the guide member  59  and guide slot  56  may permit transmission of torque forces transmitted from and between the cam and module.  FIG. 4A  illustrates a cam module position that provides a relatively light draw weight. Similarly,  FIG. 4C  illustrates the positioning of the module to provide a heavy draw weight, while  FIG. 4B  illustrates the positioning of the module for a medium draw weight. As described above in connection with the positioning of a specific module on the cam, the module may be reversed or “flipped” to change the draw length independently of the draw weight. 
   Thus it may be seen that a pair of modules, one each for the upper and lower cams of a dual cam bow, may be used as in the example given above. That is, each module may be attached to a corresponding cam to provide a selected draw length; that same cam may be positioned on the corresponding cam by sliding/translational movement to a desired draw weight position. Thus, the individual modules permits the selection of two draw lengths combined with a selection of three draw weights for each selected draw length. Thus, an archery dealer having an inventory of selected bows may provide a prospective purchaser with a bow of the characteristics chosen by the purchaser together with a set of attachable modules to permit the purchaser to customize the bow. The combination of available draw lengths and draw weights permits the purchaser to select the appropriate weight and draw length while permitting the dealer to stock fewer bows since each bow can be customized over a broad range of draw weights and draw lengths. 
   As an example of the implementation of the present invention, the following chart provides a selection of module sizes together with the available draw lengths and weight settings available with the respective modules. Assuming for example, the archer desires a 28″ draw length. From the chart below it may be seen that he would select module C″. If the archer desired an approximate 65 pound peak draw weight, the archer would select the medium or “M” translational position of the module on the cam. With the module thus in the proper position on the cam, the module is then secured to the cam with two screw fasteners that are aligned with corresponding threaded holes in the cam. Minor weight adjustments may subsequently be made by turning the limb screw bolts to “fine tune” the desired weight. 
   
     
       
             
             
             
             
             
             
           
             
             
             
             
             
             
           
             
             
             
             
             
             
           
         
             
                 
                 
             
             
                 
                 
                 
               Approx. 
                 
                 
             
             
                 
               Module 
               Weight 
               Draw 
               Approx Weight Range 
             
           
        
         
             
                 
               No. 
               Setting 
               Length 
               60# Peak 
               70# Peak 
             
             
                 
                 
             
           
        
         
             
                 
               A 
               H 
               31.50 
               40-60 
               50-70 
             
             
                 
               A 
               M 
               31.25 
               35-55 
               45-65 
             
             
                 
               A 
               L 
               31.00 
               30-50 
               40-60 
             
             
                 
               B 
               H 
               30.50 
               40-60 
               50-70 
             
             
                 
               B 
               M 
               30.25 
               35-55 
               45-65 
             
             
                 
               B 
               L 
               30.00 
               30-50 
               40-60 
             
             
                 
               C 
               H 
               29.50 
               40-60 
               50-70 
             
             
                 
               C 
               M 
               29.25 
               35-55 
               45-65 
             
             
                 
               C 
               L 
               29.00 
               30-50 
               40-60 
             
             
                 
               C′ 
               H 
               28.50 
               40-60 
               50-70 
             
             
                 
               C′ 
               M 
               28.25 
               35-55 
               45-65 
             
             
                 
               C′ 
               L 
               28.00 
               30-50 
               40-60 
             
             
                 
               B′ 
               H 
               27.50 
               40-60 
               50-70 
             
             
                 
               B′ 
               M 
               27.25 
               35-55 
               45-65 
             
             
                 
               B′ 
               L 
               27.00 
               30-50 
               40-60 
             
             
                 
               A′ 
               H 
               26.50 
               40-60 
               50-70 
             
             
                 
               A′ 
               M 
               26.25 
               35-55 
               45-65 
             
             
                 
               A′ 
               L 
               26.00 
               30-50 
               40-60 
             
             
                 
                 
             
           
        
       
     
   
   Thus, it may be seen that the dealer may stock a single bow and provide that bow to an archer with a total of eighteen selected values for draw weight and length. 
   The present invention has been described in terms of selected specific embodiments of the apparatus and method incorporating details to facilitate the understanding of the principles of construction and operation of the invention. Such reference herein to a specific embodiment and details thereof is not intended to limit the scope of the claims appended hereto. It will be apparent to those skilled in the art that modifications may be made in the embodiments chosen for illustration without departing from the spirit and scope of the invention.