Abstract:
A dampening device for an archery bow, the dampening device absorbing vibrational energy as the limbs of the bow return to a rest position from a drawn position, the dampening device comprising at least one counterweight mounted to a resilient member. The resilient member mounted to a dampening device mounting region located on the handle, riser or limbs of the bow.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     This invention relates to archery bows and accessories thereof, and more particularly to a damping device or devices to be incorporated into a bow handle to absorb excess energy thereby reducing hand shock, noise and bow vibration. 
     Most everyone is familiar with the archery bow and arrow. The bow is a rather simple mechanical device used to store energy derived from the archer during the drawing of the bow and then when the archer looses the bow string the bows energy is rapidly released. The greater portion of this energy goes into the launching of the arrow and most of the remainder finds its way back into the bow with the excess resulting in noise or simply lost in the transfer process. Some of the energy that goes back into the bow returns it to its original undrawn state but much of it goes into moving various bow components resulting in bow hand shock and system vibrations. 
     Over the years archery manufactures have attempted to make the bow more efficient and in some ways they have succeeded. The compound bow is an example of the modem manufactures success in being able to increase the amount of energy that a bow can store, some modem compound bows store almost 50% more energy per peak pound of draw weight as did the longbows of years past. The basic premise being that the more energy stored the more energy one has available to launch the arrow and the result will be greater and greater arrow launch velocities. To some extent this has become true and arrow initial velocities for bow hunters have increased over the last couple of decades. Along with bows that are capable of storing energy more efficiently, the quest for higher arrow velocities has been further augmented by the fact that lighter mass weight arrows have greater launch velocities than do heavier mass weight arrows. Arrow manufactures in the last two decades have taken advantage of the availability of higher strength materials and made lighter and lighter mass weight arrows available. 
     The result is that today&#39;s bows are storing more energy and are being used to launch lighter and lighter mass weight arrows. The problem arises from the fact that the amount of energy that a given bow can transfer to an arrow is directly proportional to the mass weight of the arrow being shot. The overall mechanical efficiency of the bow is determined in the usual fashion in that we look at the ratio of the energy coming out of the system divided by the energy that was put into the system. In this case we have the kinetic energy in the arrow at launch divided by the energy put into the bow by the archer prior to arrow launch. In this manner it is easily verifiable that bows in general can have efficiencies of nearly 90% when shooting very heavy mass weight arrows and the same bow can exhibit efficiencies in the lower 60 percentile when shooting very light mass weight arrows. The result is that a bow shooting heavy mass weight arrows imparts most of its stored energy to the arrow and after launch the bow must absorb only 10% of the original stored energy. On the other hand if the same bow were to shoot very light mass weight arrows it would have to absorb up to 40% of the original stored energy after each launch. 
     A number of the compound bows being offered today can store as much as 100 foot pounds of energy therefore it is conceivable that such a bow shooting a very light weight arrow could have to absorb up to almost 40 foot pounds of energy after each arrow launch. This excess energy trapped in the bow often results in a great deal of bow shock and vibration which is not only unpleasant to the archer but also takes its toll on the bows components and the accessories mounted to the bow. 
     Although some manufactures have tried to address the problem of this residual energy by using after market shock absorbing stabilizers and several patents have been issued for such devices (e.g. U.S. Pat. No. 5,016,602 and U.S. Pat. No. 5,411,009). These devices tend to be effective only along the axis on which they are mounted and the degree of damping that they provide is generally proportional to the amount of weight that they add to the system. The proposed damper is designed to be multi-axial in its ability to absorb and dissipate excess energy and in comparison it adds much less mass weight making it much more effective than previous dampers. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is directed to a damper for reducing or dissipating energy. Specifically, the present invention addresses the problem of the excess energy that the bow is unable to transfer to the arrow during each shot by providing the bow with one or more energyabsorbing dampers. The present damper may be designed to fit into or be an integral part of a bow handle. The present damper may dissipate 20% or more of the excess energy created by the recoil of a the bow during and subsequent to shooting of the bow. This dissipation of energy reduces vibration making the shooting of the bow more pleasant and resulting in a quieter bow with less damage to bow components and accessories. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     A detailed description of the invention is hereafter described with specific reference being made to the drawings in which: 
     FIG. 1 is a side elevation view of a typical compound bow and illustrates one means of incorporating the incident invention into the bow handle of that bow; 
     FIG. 2 is close up view of the upper portion of the bow handle as shown in FIG. 1 showing in more detail the location and mounting of the subject damping device; 
     FIG. 3 shows a close up side elevation view of the damper assembly and also an exploded view of the components that comprise that assembly; 
     FIG. 4 is a section view through a portion of the bow handle showing a second configuration of the handle damper with a different weighting configuration; 
     FIG. 5 shows a third section view illustrating another damper configuration having both a different elastomer mounting means as well as another weight mounting means; 
     FIG. 6 is a cross section view of a fourth means of constructing and attaching the elastomer portion of the dampers; 
     FIG. 7 is a cross section view of a damper arrangement that depicts a fifth means of securing the elastomeric portion of the damper to the bow as well as a variation in attaching the damper weights; 
     FIG. 8 is another cross section view depicting still another means of attaching the weight assembly to the elastomer portion of the damper and also illustrates another weighting configuration; 
     FIG. 9 is a graph showing the acceleration rate of the bow handle in the area of the small of the grip when the bow shoots an arrow weighing 6.2 grains per peak pound of bow draw weight and there are no dampers in the bow handle; 
     FIG. 10 is a graph showing the acceleration rate of the bow handle under the same conditions as represented in FIG. 9 except that the bow handle had dampers installed; 
     FIG. 11 is a graph showing the acceleration rate of the bow handle in the area of the small of the grip when the bow shoots an arrow weighing 5.5 grains per peak pound of bow draw weight and there are no dampers in the bow handle; 
     FIG. 12 is a graph showing the acceleration rate of the bow handle when the bow is set-up and shot under the same conditions as represented in FIG. 11 with the exception being that the bow handle was equipped with dampers; 
     FIG. 13 is a graph showing the acceleration rate of the bow handle in the area of the small of the grip when the handle without the dampers installed is suspended from one end and receives a given impact at the opposite end of the handle; and 
     FIG. 14 is a graph showing he acceleration rate of the same set-up and impact conditions as in FIG. 13 except that for this test the handle had the dampers installed. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings, FIG. 1 depicts a typical compound bow employing the latest technology including the innovative dampers which are the subject of this application. FIG. 1 is a side elevation view of the bow  1  having bow handle  2  to which are attached an upper limb  5  and lower limb  6 . The upper and lower limbs are attached to the bow handle  2  using pivotal limb mounting cups  3  and  4  respectively. The bow depicted in FIG. 1 is referred to as a compound bow because located at the extremities of each bow limb are the components comprising a variable leverage system which allows the user to hold the bow at full draw while expending less effort than required with a traditional bow. A variable leverage device  8  is pivotally mounted on axle  7  at the free end of the lower limb  6  while an idler wheel  9  is pivotally mounted on axle  10  at the free end of the upper limb  5 . This particular arrangement has become well known as, the dual feed-out single take-up, single cam system and was first disclosed in U.S. Pat. No. 5,368,006. While FIG. 1 depicts a compound bow of the single cam design the innovation which is the subject of this patent can be applied to compound bows of other designs as well as bows of traditional design. The bow handle  2  in FIG. 1 has been slightly modified at each end in the area behind the limb mounts  18  to make room for the damper assemblies  19  shown in FIG.  3 . 
     FIG. 2 is a close up view of the upper portion of the bow handle showing the damper  19  installed in area  18  of the handle. The resilient portion of the damper  20  has an external annular collar  24  best seen in FIG. 3 that mechanically retains the elastomeric portion of the damper in a corresponding groove  18   a  (FIG.  2 )in the area  18  of the bow handle  2 . In this case the elastomer is inserted into the opening in area  18  of the handle, and the two halves of the weight  26  and  28  are inserted into central opening such that the retaining grooves  38  on each weight half engages the mating portion  36  on the elastomer and the two halves are then secured together with capscrew  32 . With the weight in place the elastomer is reinforced such that it is securely held in position mechanically. FIG. 3 shows an exploded view of the elastomer  20  and the components of the weight  26 , 28  and fastener  32 . 
     The concept of inserting an elastomeric damper material into an opening in the bow handle and having that damper material affixed to an inertial mass can be accomplished effectively in a number of different ways. FIG. 4 shows a different shape of the elastomeric damper  40  and the in this case larger weights  46  and  48  are aligned to the damper material matching the annular projection of the damper material  44  with the annular grooves in the weights  50  and attached with capscrew  52 . 
     FIG. 5 shows the damper material  60  which is adhesively bonded into the handle  2  at bond line  61  and the weight  70  has a male threaded portion  72  which engages the female threaded portion  76  of the second part of the inertial weight  74 . The inertial weights  70  and  74  are located in a mated opening  62  in the damper material  60  and tightened securely against a portion of that material  64 . 
     FIG. 6 shows another arrangement where the damper is composed two halves  80  and  81  respectively. Each damper half has a portion  83  that fits closely into an opening in the handle for proper alignment additionally each half also has a flanged portion  82  which over laps said opening in the handle such that when the damper halves  80  and  81  are inserted into each side of the handle  2  and the corresponding weights  84 , 86  are inserted into pockets in the damper halves and drawn together with fastener  88  the complete damper assembly is held securely into the bow handle  2 . Depending on how tightly the weights  84 , 86  are drawn into the damper material  80  one has a means to adjust the dampers response without having to make a damper material change. 
     FIG. 7 shows a damper arrangement where the damper material fits into an opening in the bow handle with excess damper material exposed on each side of the handle. The exposed outer surfaces of the damper are engaged by compression plates  86  on both sides of the handle. The compression plates and the damper each have a central opening through which a threaded rod extends. Nuts are threaded on to each end of the threaded rod and engage the compression plates  86  as the nuts  90  are tightened the compression plates  86  apply pressure to the elastomeric damper material  82  causing it to deform  84  around the opening in the bow handle effectively locking the damper in place in the handle  2 . Another aspect of this arrangement is that the response of the damping material can also be adjusted by controlling the pressure that the compression plates  86  apply against the damper material  82 . An additional feature of this arrangement is that the mass weights  96  can be variably positioned on either side of mounting rod  92  and locked in position using set-screws  94  giving another dimension of adjustability. 
     FIG. 8 shows still another arrangement of the damper assembly. In this arrangement the weight supporting rod  106  is attached directly to the damper material  100  either adhesively or as shown here the rod may be designed to be vulcanized, cast, or injection molded  104  into the damper material. This arrangement also shows the versatility that can be achieved in both the amount of weight units  110  and the positioning of the weight to be used. Weights  110  can be located in various positions on rod  106  and secured into position with setscrews  112 . 
     The dampers shown in FIG. 1, FIG. 2, and FIG. 3 are circular in design for several reasons, the circular design is equally responsive in all radial directions in solid or with symmetrically designed openings in the dampers resulting in the ability to absorb energy in a multitude of directions. While the circular design has some obvious manufacturing benefits the dampers could be manufactured in other shapes and be installed in other areas of the bow handle with varying degrees of effectiveness depending on the location chosen and the particular damper design. The effectiveness of dampers as disclosed herein also depends on the damping coefficient of the material chosen the durometer of that material and the final geometry of the damper as well as the configuration and density of the weights attached to the damping material. Dampers of the configuration shown in FIG. 3 were tested using various materials and material compositions for the elastomer portion  20 . Amongst the materials first tested were Anyln ™ and Santoprene ™ both in several different durometers (hardness) which gave the indication that the concept could provide the desired effect of making a significant reduction in the shock, vibration and a reduction in the total energy that reaches the users bow hand. The results with the materials used to date also indicates that the dampers performance can be tailored to a given weight range of arrows to be shot and a damper material that performs exceptionally well with light weight arrows may not give the best results when shooting heavier weight arrows. 
     The test bow as shown in FIG. 1 was fitted with an accelerometer  16  located on the back of the handle directly across from the low point in the bows grip. The accelerometer  16  was positioned so as to detect the acceleration rate of the handle in this area in the direction parallel to the arrows launch path. That signal was sent to a Tektronix™ 336 digital storage oscilloscope and then down loaded to a personal computer. Some of the test results are shown here in FIG. 9 thru FIG.  14 . FIG. 9 shows the acceleration rate at the grip versus time plot when the bow is shot with a 431 grain arrow and no dampers installed and FIG. 10 shows the same bow set-up with a specific damper installed and shooting the 431 grain arrow. Analysis of these two graphs shows that the average shock force at the bow hand was reduced by 7% while the peak shock forces were reduced by 5%. FIG. 11 shows the results of shooting the same 30″ draw, 70# peak weight bow with out dampers and shooting a 385 grain arrow. FIG. 11 should be compared with the chart of FIG. 12 which shows the bows response with dampers installed and shooting the same 385 grain arrow. Analysis of these two graphs indicates that the addition of the dampers resulted in a 13.5 to 15% reduction in the average shock force reaching the archers hand and nearly a 20% reduction in the average Peak shock forces at the archers bow hand. These were rather unexpected results in that most after market shock absorbing stabilizers add considerably more mass to the system and result in providing no more damping effect and in many cases they have less damping effect on the forces and energy reaching the archers bow hand. It can also be shown from the graphs of FIGS. 11 and 12 that when the bow is equipped with dampers the total energy that the bow hand is exposed to is reduced by 10%. 
     A second benefit of the dampers is the effect that they have on the secondary ringing vibrations that can occur in the handle when the arrow is shot. This is the same type of effect that occurs when such items as baseball bats, tennis rackets, hammers etc. are subjected to sudden load application or impact. The resulting ringing or stinging vibrations that can occur are less than pleasurable and can effect the users performance. To test the effectiveness of the handle dampers on this type of vibrations the bow handle  2  was disassembled from the bow and freely suspended from one end with the accelerometer  16  attached as described earlier. The handle was then impacted identically with and without the dampers installed. FIG. 13 is the graph of the bow handles response when the dampers were removed and FIG. 14 is the response of the handle with the dampers in place. Comparing the graphs, one finds that the handle with dampers has a reduction of 20% in the magnitude of the peak acceleration forces over the first 75 milliseconds after impact and the time required for the major vibrations to dampen out was reduced by a factor of 3.5 to 5.5 depending on the specific damper configuration and damper material used. 
     The invention may be embodied in many forms without departing from the spirit or the essential characteristics of the invention. For example, a number of variations on the configuration of the elastomeric portion of the damper and the means of attaching that portion to the bow handle along with several different weighting concepts and means of attachment of those weights to the elastomeric portion have been disclosed but they do not by any means cover the full scope 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. All changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein. 
     In addition to being directed to the embodiments described above and claimed below, the present invention is further directed to embodiments having different combinations of the features described above and claimed below. As such, the invention is also directed to other embodiments having any other possible combination of the dependent features claimed below. 
     The above examples and disclosure are intended to be illustrative and not exhaustive. These examples and description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the attached claims. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims attached hereto.