Abstract:
String silencers for reducing the sound made when an arrow is released from a bow. These silencers are made from a material which allows the silencer to freely flex when the arrow is released and the bow string begins to vibrate. Silencers usable with conventional bow strings and with split bow strings are disclosed. Disclosed silencers for conventional bow strings have uniform and necked down configurations, and a representative, disclosed silencer for split bow strings has a center segment and integral arms at opposite ends of the center segment. With the silencer at rest, these arms extend in opposite directions from, and at equal angles to, the center segment.

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to archery bows and more, particularly, to novel, improved devices for minimizing the sound generated by a bow string when an arrow is released. 
     BACKGROUND OF THE INVENTION 
     A bow string makes a relatively loud sound when an arrow is released. This is disadvantageous as the sound may be loud enough to frighten away game a hunter is seeking or cause the bowman to flinch and the arrow to consequently go astray. 
     A variety of silencers for bow strings are available from Martin Archery, Cabala&#39;s Archery, and other sources. Available string savers are of several different types. One, due to its shape, is known as a “puff silencer.” Puff silencers are typically made of leather and yarn strands. 
     A second type of silencer is the “whisker silencer,” also named for its appearance. The whiskers of the silencer are commonly made from a rubber or comparably flexible material. 
     Other commercially available string silencers are made from fleece and such exotic materials as beaver hide. 
     The available devices, however, are not as effective as one might wish. Therefore, there is a continuing need for a better string saver. 
     SUMMARY OF THE INVENTION 
     There have now been invented and disclosed herein certain new and novel string silencers which are highly effective. Another advantage of the string silencers disclosed herein is that the reduction in initial arrow velocity, inevitably associated with the use of a string silencer, is very small. 
     One type of string silencer embodying the principles of the present invention and having the just-discussed advantages is a strip-like device fabricated from vibration damping material. These string silencers are knotted onto the bow string, one at each end of the string. 
     A second type of string silencer also embodying the principles of the present invention, is likewise fabricated from a vibration damping material. This string silencer is installed between the two parts of a split bow string and retained in place by complementary, integrated, silencer bosses. Split bow strings are commercially available, and other bow strings can be split to accommodate the silencers with a conventional string splitter. 
    
    
     The objects, novel features, and advantages of the present invention will be apparent to the reader from the foregoing and the appended claims and as the ensuing detailed description and discussion proceeds in conjunction with the accompanying drawing. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a compound bow equipped with string silencers embodying the principles of the present invention; 
     FIG. 2 is a fragment of FIG. 1 drawn to an enlarged scale to better show how a FIG. 1 silencer is attached to the string of the FIG. 1 bow; 
     FIG. 3 is a perspective view of the silencer; 
     FIG. 4 is a section through the silencer, taken along line  4 — 4  of FIG. 3; 
     FIG. 5 is a perspective view of a second string silencer embodying the principles of the invention; this silencer differs from the FIG. 3 string silencer in that it has a necked down center section; 
     FIG. 6 is a fragmentary view of a compound bow equipped with a third type of flexible string silencer which embodies the principles of the present invention and is designed for use with a split bow string; 
     FIG. 7 is a right-hand side view of the split bow string and string silencer; 
     FIG. 8 is a left-hand side view of the bow string and silencer; 
     FIG. 9 is an end view of the string silencer; 
     FIG. 10 shows the configuration assumed by the FIGS. 6-9 string silencer in that moment immediately following the release of an arrow; this configuration is effective in reducing the drift of an arrow when the arrow is released. 
     FIG. 11 is similar to FIG. 8 but shows how the string silencer might wiggle and jiggle to alter vibration patterns and reduce the sound generated when the bow string is released; 
     FIG. 12 is a graph showing the significant extent to which the magnitude of sounds in a wide range of frequencies are reduced by employing string silencers as illustrated in FIGS. 6-10; and 
     FIG. 13 is a graph showing how string silencers illustrated in FIGS. 6-10 significantly reduce the level of the sound (or twang) generated when an arrow is released from a bow equipped with such silencers. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, FIG. 1 depicts a compound bow  20  equipped with string silencers  22  and  24  in accord with the principles of the present invention. Bow  20  has flexible limbs  26  and  28  mounted to the opposite ends of a riser  30  and a bow string  32 . The bow string is strung around cams  34  and  36  at the ends of limbs  26  and  28  with the ends of the bow string being anchored to the shafts  38  and  40  which support cams  34  and  36  from the limbs  26  and  28  of bow  20 . 
     The two bow string silencers  22  and  24  are duplicates; accordingly, only bow string silencer  22 , shown in more detail in FIGS. 2-4, will be described in detail herein. 
     Bow string silencer  22  is an elongated strip of an elastomeric material. Silencer  22  has a generally rectangular cross-section. This cross-section is uniform over the length of the silencer. 
     One material from which string silencer  22  can be made is NAVCOM. NAVCOM is a soft, amphorous, rubber-like material which contains a mixture of chloroprene and butyl polymers and the following physical properties (representative). 
     
       
         
               
             
               
               
               
               
               
               
             
               
               
             
           
               
                   
               
             
             
               
                 Shore A hardness: 17-90 
               
             
          
           
               
                   
                   
                 Ultimate 
                 Tensile 
                   
                   
               
               
                   
                 Shore 
                 Elongation 
                 Strength 
                 Compression 
                 Specific 
               
               
                 Environment 
                 A 
                 (Percent) 
                 (PSI) 
                 Set (Percent) 
                 Gravity 
               
               
                   
               
               
                   
                  7 
                 1,075 
                 373 
                 6.01 
                 1.014 
               
               
                   
                 12 
                 900 
                 643 
                 7.3 
                 1.025 
               
               
                   
                 20 
                 835 
                 1,069 
                 6.9 
                 1.063 
               
               
                   
                 30 
                 1,056 
                 1,621 
                 4.0 
                 1.074 
               
               
                   
                 40 
                 326 
                 1,453 
                 N/A 
                 1.185 
               
               
                   
                 90 
                 175 
                 2,440 
                 N/A 
                 1.379 
               
               
                 Oven aged 
                  7 
                 N/A 
                 N/A 
                 56.3 
                 — 
               
               
                 For 
                 12 
                 — 
                 — 
                 31.1 
                 — 
               
               
                 70 hrs at 
                 20 
                 — 
                 — 
                 30.8 
                 — 
               
               
                 212 = 5° F. 
                 40 
                 — 
                 — 
                 22.4 
                 — 
               
               
                   
                 90 
                 — 
                 — 
                 18.6 
                 — 
               
               
                   
               
             
          
           
               
                 Resilience: 
                 At room temperature - Medium 
               
               
                   
                 At high temperature - Fairly high 
               
               
                 Heat resistance 
                 Good 
               
               
                 Outdoor aging resistance: 
                 Excellent 
               
               
                 Low temp flexibility: 
                 Good 
               
               
                 Abrasion resistance: 
                 Good 
               
               
                 Flex life: 
                 Good 
               
               
                 Solvent resistance: 
               
               
                 Hydrocarbons - 
                 Fair to good 
               
               
                 Oxygenated - 
                 Fair to good 
               
               
                 Air permeability: 
                 Low to moderate 
               
               
                 Moisture resistance: 
                 Fair 
               
               
                 Useful operating temperature: 
                 −40° to 250° F. 
               
               
                   
               
             
          
         
       
     
     The approximate dimensions of a representative string silencer as shown in FIGS. 3 and 4 are: 
     
       
         
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Length (l) 
                 3.25 
                 in 
               
               
                   
                 Width (w) 
                 0.38 
                 in 
               
               
                   
                 Thickness (t) 
                 0.1 
                 in 
               
               
                   
                   
               
             
          
         
       
     
     As shown in FIGS. 1 and 2, string silencer  22  is attached to that run  42  of bow string  32  in which arrows are nocked as by knotting the silencer around the bow string with the illustrated overhand knot  44 . 
     Bow string silencer  22  is thus attached to bow string  32  at one end  46  of run  42 . The second bow string silencer  24  is in the same fashion attached to bow string run  42  near its opposite end  48 . 
     As indicated by arrows  50  and  52  in FIG. 2, the just-described method of assembling bow string silencer  22  (and bow string silencer  24 ) to bow string run  42  leaves the two string silencer segments  54  and  56  on opposite sides of knot  44  free to oscillate,bend, and otherwise flex relative to the knot, and vibrations may also be set up within each of the two string silencer segments  54  and  56  on opposite sides of knot  44 . The result of this wiggling and jiggling is an altered pattern of bow string vibration and a marked decrease in the level of sound (or twang) generated when an arrow is released. At the same time, and in contrast to typical, heretofore available string silencers, the loss in arrow velocity attributable to the presence of the string silencers is minimal (typically, not more than two feet per second). 
     Referring still to the drawing, FIG. 5 depicts a second string silencer  60  also fabricated in accord with, and embodying, the principles of the present invention. This string silencer, also employed in pairs with one silencer at each end of the bow string run in which an arrow is nocked, differs from silencer  22  in that it has a necked down center segment  62  located between two integral end segments  64  and  66 . This optional necked down section stretches and contracts to keep the string silencer in place when an arrow is released and the bow string vibrates. In most cases, however, this enhancement of the string gripping capability of the silencer is not necessary as the NAVCOM or comparable material provides adequate gripping ability due to its softness. 
     As just suggested, string silencer  60  may be fabricated from the same types of materials as string silencers  22  and  24 ; and it will typically have the same dimensions as those silencers. 
     With continued reference to the drawing, FIG. 6 depicts, in fragmentary form, a compound bow equipped with string silencers (only one of which is shown) of the type shown in more detail in FIGS. 7-11. The string silencer is identified by reference character  70 . 
     The FIG. 6 bow may duplicate the bow shown in FIG.  1 . Accordingly, the same reference characters have been employed to identify the two bows and their components. 
     Silencer  70  has a center segment  72  and integral arms  74  and  76 , one at each end of the central segment. These arms extend at right angles from central segment  72  and in opposite directions from that segment as indicated by arrows  78  and  80  in FIG.  7 . From the side, the width w 1  of arms  74  and  76  is uniform (see FIGS.  7  and  8 ). End on, the arms have a wedge shape, being thicker at the ends integrated with center silencer segment  72  than at their outer ends as indicated by t 1  and t 2 . 
     There are two complementary pairs of bosses or protrusions on each side of string silencer central segment  72 . On that side  82  of string silencer  70  shown in FIG. 7, one pair of bosses is identified by reference character  84 . This pair is composed of bosses  86  and  88 . 
     The second, complementary pair of bosses on the same side  82  of string silencer  70  is identified by reference character  90  with reference characters  92  and  94  identifying the bosses per se. 
     The two pairs of bosses on the opposite side  96  of string silencer  70  (see FIG. 8) are identified by reference characters  98  and  100  with reference characters  102  and  104  identifying the two bosses in pair  98  and reference characters  106  and  108  identifying the two bosses in pair  100 . 
     String silencer  70  (and its companion) may be fabricated from the same NAVCOM material as string silencers  22 ,  24 , and  60 . Representative dimensions (approximate) of a string silencer as shown in FIGS. 6-11 are: 
     Center Segment 
     
       
         
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Length (l c ) 
                 0.44 
                 in 
               
               
                   
                 Width (w c ) 
                 0.25 
                 in 
               
               
                   
                 Thickness (t c ) 
                 0.19 
                 in 
               
               
                   
                   
               
             
          
         
       
     
     Arms 
     
       
         
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Length (l a ) 
                 0.34 
                 in 
               
               
                   
                 Width (w a ) 
                 0.22 
                 in 
               
               
                   
                 Thickness (inner end, t 1 ) 
                 0.19 
                 in 
               
               
                   
                 Thickness (outer end, t 2 ) 
                 0.13 
                 in 
               
               
                   
                   
               
             
          
         
       
     
     String silencer  70  (and its companion) are installed between the elements  110  and  112  of the split bow string run  114  shown in FIGS. 6,  7 ,  8 ,  10 , and  11 . Element  110  is trapped between the two pairs of bosses  84  and  90  on side  82  of string silencer  70 . Split bow string element  112  is similarly trapped between the two pairs of bosses  98  and  100  on the opposite side  96  of the string silencer. 
     The just-described arrangement secures string silencer  70  in place on bow string run  114  while leaving the two arms  74  and  76  of the string silencer free to oscillate, bend, and otherwise move relative to the central segment  72  of the string silencer when an arrow is released. This is suggested by the three sets  116 ,  118  and  120  of dotted lines in FIG.  11 . Vibrations can also be set up in the two arms  74  and  76  of the silencer and, to a lesser extent, in the central segment  72  of the silencer. The result of this wiggling and jiggling is a marked attenuation of the sound generated when an arrow is released. 
     FIG. 10 shows, in solid lines, the relationship between the two arms  74  and  76  of string silencer  70  of the moment immediately following of arrow release. In particular, the two arms during that moment assume a parallel relationship with the arms: (a) at equal distances from the bow&#39;s (and bow strings) axis of symmetry  122 , and (b) trailing center segment  72 . This ensures that the weight of the silencer is equal on both sides of axis  20 . As a consequence, the drift of an arrow that might occur if the weight of the silencer was unevenly distributed relative to axis  120  is avoided. 
     Gaps between the elements of a split bow string result in a loss of arrow velocity that is directly related to the width of the gap. In applications of the present invention such as that shown in FIGS. 6-8,  10 , and  11  where the string silencer  70  (on a comparable silencer) is mounted between the two elements of a split bow string, this gap can be essentially eliminated by serving in the run of the bow string in which the silencer is installed. This is done by knotting the two elements  100  and  112  of the bow string run  114  together immediately above and below the silencer (the two knots are identified by reference characters  124  and  126 ). 
     FIG. 12 is a spectral analysis of the vibrations set up in the string of a compound bow when an arrow is released: (1) with no string silencers, and (2) with two string silencers as identified by reference character  70  attached to the split string run  114  of bow string  32 . This figure shows that the string silencers significantly decrease sound producing bow string vibrations set up in the bow string when an arrow is released. 
     Complementary FIG. 13 shows that there is a marked reduction of bow string vibrations (and, accordingly, sound), particularly in those first milliseconds after an arrow is released when the vibrations are the strongest and sound the loudest. 
     As will be apparent to the reader, the present invention may be embodied in many forms without departing from the spirit or essential characteristics of the invention. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive. The scope of the invention is indicated by the appended claims rather than by the foregoing description and the drawings; and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.