Patent Abstract:
An eccentric pulley assembly is provided for a compound bow, including an eccentric base cam having a peripheral track for letting out a draw string as the bow is drawn. A power cam secured to the base cam has a cable track for taking up a power cable as the bow is drawn and a shoulder is provided for spacing the track of the base cam from the track of the power cam.

Full Description:
This application claims the priority of provisional application, Ser. No. 60/261,851 filed Jan. 15, 2001. The invention relates to archery bows and more particularly to compound archery bows utilizing separable limb and riser components. 
    
    
     BACKGROUND OF THE INVENTION 
     One of the problems with achieving accuracy has been the recoil vibration occurring as the arrow is released from the bow, which has resulted also in undue noise which startles the game. Another factor affecting accuracy is the alignment of the bow string which in the past has not provided the balance desired. To the best of my knowledge, the arrow released by prior art compound bows has not been vertically centered with the result that the torque and flex stresses on the bow upper and lower limbs has not been balanced, and accuracy has been sacrificed as a result. Moreover, the bow string has not been centered in the sense of vertical upper and lower pulley alignment and in the sense of vertical bisection of the handle. 
     Typical archery bows of the type presently utilized are disclosed in U.S. Pat. No. 5,975,067 issued Nov. 21, 1999, U.S. Pat. No. 6,035,841 issued Mar. 14, 2000, U.S. Pat. No. 6,082,346 issued Jul. 4, 2000, and U.S. Pat. No. 5,749,351 issued May 12, 1998 wherein the compound bow utilizes eccentric pulleys on the outer ends of the limbs to facilitate the draw and the arrow release. The present invention is directed to bows of this general character. 
     SUMMARY OF THE INVENTION 
     The present invention, in one aspect thereof, is concerned with the manner of mounting the resilient limbs to the handle riser as well as to the vertically centered alignment of the pulleys mounting the bow string along with the handle, and the positioning of the bow rest to achieve a vertically centered arrow relationship. This permits the archer to utilize a better balanced bow which is more accurate. Because of the balanced relationship achieved, the archer is presented with less torqueing stresses in the bow and less vibration is transferred via the bow limbs upon limb recoil and arrow release. Moreover, the positioning of the arrow in vertically centered position provides equal torque and flex forces on the limbs to generate more stored energy as the bow string is drawn. Another aspect of the invention is the provision of eccentric pulley assemblies which aid in achieving these desired characteristics. 
     A further object of the invention is to provide a limb mounting system which results in material vibration reduction and accordingly much less noise generation in the release of the arrow. This is accomplished by securing the limb inner ends to the handle riser ends by means of a novel vibration damping assembly. A limb bolt extends into a threaded vibration damping member carried by the riser at each end and a limb cup, constructed of anti-vibration material, is snugly utilized between the seat and the sides and inner end, as well as the bottom, of each limb. The installed cushioning limb cup restricts the limb from shifting laterally, and forwardly or inwardly, while permitting the limbs to flex or unflex when the archer adjusts the attachment bolt to his desired draw requirements and thereby controls the energy which will be stored in the deflected resilient limbs when the bow string is drawn. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a side elevational view of a relaxed compound single-cam archery bow utilizing the present inventive concepts; 
     FIG. 2 is a rear elevational view of a dual cam bow with the tensioning cable system omitted, illustrating various components of the bow shown in FIG. 1; 
     FIG. 3 is an enlarged fragmentary rear elevational view illustrating the relationship of the handle and bow string in more detail; 
     FIG. 4 is an enlarged perspective view of the handle illustrating the handle recess which mounts on the riser in a manner to provide the top to bottom centering of the bow string; 
     FIG. 5 is a somewhat enlarged side elevational view of the limb and riser assembly only; 
     FIG. 6 is an exploded view thereof on a slightly enlarged scale showing the various component parts thereof; 
     FIG. 7 is a similar exploded view on a more enlarged scale showing the parts at the inner end of the lower limb; 
     FIG. 7A is a perspective plan view showing the limb end received in the limb cup and limb seat; 
     FIG. 8 is a perspective elevational view of the limb pocket component on an enlarged scale; 
     FIG. 9 is an enlarged perspective view of the limb cup which fits in the limb pocket; 
     FIG. 9A is an exploded perspective plan view illustrating an alternative limb cup structure; 
     FIG. 10 is an enlarged perspective view of one of the identical limbs; 
     FIG. 10A is a perspective plan view of an alternative limb; 
     FIG. 11 is an enlarged perspective, exploded view of the limb bolt bushing assembly; and 
     FIG. 11A is a similar view disclosing an alternative embodiment; 
     FIG. 12 is a rear elevational view of a bow employing eccentric cam assemblies at each of its upper and lower ends; 
     FIG. 13 is an enlarged view of the upper end of the bow shown in FIG. 12; 
     FIG. 14 is an enlarged view of the lower end of the bow shown in FIG. 12; 
     FIG. 15 is a considerably enlarged view of eccentric pulley assembly which may be used at both ends of the bow; 
     FIG. 16 is an enlarged perspective view of the eccentric pulley assembly only; and 
     FIG. 17 is an edge elevational view of a base cam/power cam eccentric pulley assembly. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring more particularly to the accompanying drawings, and in the first instance to FIG. 1 thereof, the bow assembly comprises generally upper and lower resilient limbs generally designated  10  and  11  joined in the manner to be disclosed to a rigid riser, generally designated  12 , which can be fashioned of aluminum or other suitable material. Revolvable mechanical advantage creating pulley members  13  and  14  are mounted laterally centrally at the outer ends of the limbs  10  and  11 . The members  13  and  14  may comprise regular idler pulleys or eccentric pulleys and in FIG. 1 a regular pulley is shown at  13  and an eccentric pulley at  14 . They operate in the usual manner to mount the bow string  15  shown in FIG. 1, which in the embodiment shown is part of the conventional tension cable system generally designated TC which extends between the opposite ends of the bow in the usual manner. The cables TC-1 and TC-2 of the conventional cable system, pass through spaced apart openings in a cable guard rod r which holds the cables laterally apart and displaced sufficiently from arrow  16  to avoid feather damage. Here the cable TC-1, which provides the bow string portion  15 , passes around pulley  13  and pulley  14  and secures at both ends to eccentric pulley  14 . Cable TC-2 is shown as connected to limb  10  at one end and to the pulley  14  at the other. In FIG. 2, a conventional eccentric pulley is used in the upper end of the bow at  13   a  and on the lower end of the bow at  14 . It will be noted that the arrow  16  is vertically centered with respect to the axes of axles  18  and  19  on which the pulleys  13  or  13   a  and  14  are mounted for rotation. This tends to prevent the bow from tilting vertically on the draw. 
     As FIG. 3 further indicates, the pulleys  13  or  13   a  and  14  are so aligned vertically, and the handle  12   a  is so mounted on the riser  12 , that the string  15  vertically bisects the bow handle  12   a  in a front to rear direction. While the bow string  15  is offset with respect to the mid-portion of the riser, it is substantially centered with respect to the handle  12   a,  as FIG. 3 particularly indicates. This is possible because the vertical mounting recess  12   b  (FIG.  7 ), in the handle  12   a  is centrally offset in the handle to define narrow riser embracing leg  12   g  and wider embracing leg  17   h.  Handle leg  12   h  fits within the recess  12   c  provided in the one side face of the riser  12 . Cap screw openings x in the handle and riser, for accommodating a fastener such as a screw, align. Plainly this centering of the bow string  15  with respect to the handle  12   a,  and consequent centering of the string and arrow  16  with respect to the handle  12   a,  can be accomplished alternatively by offsetting the mounting portion of the riser sufficiently that the bow string  15  bisects a handle  12   a  mounted non-eccentrically on the riser  12 . The riser  12 , as usual, has a number of weight reduction openings and an arrow rest surface  12   d  which is equidistant from the axes of each pulley  13  or  13   a  and  14  and aligns substantially with the vertical center of the bow string  15 . 
     Another important aspect of the present invention is the anti-vibration mounting of the limbs  10  and  11  to the riser as disclosed particularly in FIGS. 6-11. It will be observed that each of the composite material limbs  10  and  11 , which are identical, include outer end bifurcation slots  20  within which the inner portions of the pulleys may be rotatably received, and bores  21  for receiving and securing the pulley axle pins  18  and  19 . While a mediate slot  22  is provided in each of the limbs in FIG. 10 to increase flexing capability it will be noted that the slot  22  does not extend the full length of the limbs  10  or  11  and, rather, torsion restricting portions  23  are provided at each end of the slot  22 , as shown. The inner ends of the limbs  10  and  11  are similarly bifurcated as at  24  (FIG. 7) for a purpose to be presently described. An alternative limb  10  or  11 , using like numerals to designate the respective parts, is shown in FIG.  10 A. 
     Bolted to the ends of the riser  12 , as with bolts  25 , are metallic (preferably aluminum) limb seats or pockets generally designated  26  (FIG. 8) having spaced openings  27  in their recessed bottom walls  26   a  to accommodate the bolts  25  securing the seats  26  to the riser  12  ends. As indicated, the bottom surfaces of seat walls  26   a  have recesses  26   b  (FIG. 7) to receive the protrusion or key portions  12   f  provided on the risers  12  to fit snugly therein. It will be noted that the limb seats or pockets  26  are of an elongate nature and have side walls (see FIG. 6)  28  joined by a generally curvilinear inner end wall  29 . The opposite end of each limb seat  26  is open as shown. An elongate opening  30  is also provided in the bottom wall  26   a  of the limb seat to pass a limb attaching metallic (preferably steel) fastener assembly or bolt  31  (FIG. 7) in a manner to be presently described. 
     Provided to seat snugly within the limb seat  26  is a preferably molded, vibration damping limb receptor cup generally designated  32  (FIG. 9) which has similar side walls  33  joined by a similar generally curvilinear end wall  34 . Each limb cup  32  includes a bottom wall  32   a  with an elongate opening  35  therein aligning with seat opening  30  to also pass the attachment bolt  31 . At its opposite end, the limb cup  32  is open to pass the inner end of the limb and mounts a pair of limb locator bosses  36 , as shown, which are received within the spaced apart blind openings  37  (FIG. 10) provided in the bottom surfaces of limbs  10  and  11 . The same bosses are provided, but not shown, in FIG.  10 A. The walls  33  and  34  of each limb cup are snugly received within and braced by the walls  28  and  29  of the limb seat component  26  with a perimetral clearance of only about 0.005 of an inch. Provided on the limb cups  32  near their outer ends are curvilinear rockers  38  which are received in the curvilinear receiving recesses  39  provided in the seats  26 . In addition to permitting some adjustment pivoting when the bolt  31  is adjusted to tension the limbs  10  and  11  to adjust the weight of the bow, they also serve as locator mechanism. It is to be understood that the limb cups  32  are formed of a polyurethane or other suitable resilient synthetic plastic material having a durometer which typically may be 60. The particular durometers mentioned in this application are not to be considered as in any way limiting and other durometers will prove useful so long as they provide the anti-vibration characteristics. A durometer range for the cups  32  is believed to be 30-90. The limbs  10  and  11  are preferably constructed in the usual manner of a composite material such as fiberglass or graphite with embedded fibers which may typically be glass or carbon to provide the requisite strength. The cups  32  need not be completely formed of the same material. In FIG. 9A an improved alternative is disclosed wherein the bosses  36  and rocker  38  are unitarily molded of a harder material such as “delrin plastic”. The term Delrin is a trademark owned by E. I. du Pont de Nemours and Co. Inc. for its acetal homopolymer plastics which are mechanically strong while also having resilience. In this version, the upper wall of the rocker is flat as at  38   a  to lie in the same plane as the outer limb receiving surface of the bottom wall when the bosses  36  are inserted up through the opening  38   b  and the rocker  38  is secured in opening  38   b  adhesively, or in any other suitable manner. Another alternative is to cut away part of the cup bottom wall  32   a  as at  32   c  to receive an insert plate  32   d  of material having a lower durometer than wall  32   a.  This lower durometer is in the range 10-30 and preferably about 20. 
     As shown in FIG. 7, the bolt  31  is part of a fastener assembly which includes an aluminum washer  40  and the polyurethane anti-vibration washer  42 , typically having a durometer rating in the 50-60 area. The bolt  31  extends through the slotted opening  24  in the inner end of limb  10  or  11 , through slotted opening  35  in the limb cup  32  and  30  in the limb seat  26  and through a slot  12   s  in riser  12  into a polyurethane or similar bushing generally designated  43  having a bolt receiving bore  44  provided therein. Bushings  43  seat snugly within bores  12   e  provided in each end of the riser  12  inboard of each seat  26 . Provided embedded within the bushing  43  is a preferably stainless steel cylinder  45  (FIG. 11) having a threaded bolt receiving bore  46  aligning with bore  44 . End caps  47  and  48  of greater external diameter than the bushing opening  12   e  (FIG. 7) are received on the reduced ends  43   a  of the bushing  43 . The end caps  47  and  48  are preferably adhesively secured to the bushing ends  43   a  and bear against the marginal surface of the riser surrounding the opening  12   e  in which the bushing  43  is received. The durometer of the molded sleeve member  43  with reduced ends  48  may typically be in the area of 70-90. The end cap  47 - 48  durometer is preferably in the range 30-50. The purpose of the polyurethane sleeve bushing  43  is to dampen recoil vibration transmitted by the attachment bolt  31  and to resist forces tending to twist the handle  12   a.  The bushing  43  and cylinder  45  also resist outward pull of the bolt  31 . The provision of the cups  32 , which cushion or absorb the recoil of the limbs  10  and  11 , prevents much of the recoil vibration from reaching the limb seats  26  and, in addition to preventing torsional forces from reaching the riser and handle, also damps vibration resulting from the flexing of the bow limbs  10  and  11 . 
     In FIG. 11A an improved alternative embodiment is disclosed in which bushing  43  is eliminated and cylinder  45  is formed of “Delrin” plastic as a damping body. The ends of cylinder  45  are closed as at  50  except for openings  51 . The openings  51  receive projections  52  extending from cap  47  and cap  48  which may have a durometer rating in the 15-25 range. The noise reducing caps  47  and  48  are preferably adhesively secured to cylinder  45 . 
     Referring now more particularly to FIGS. 12-16 a three cable draw and tensioning system is disclosed wherein novel eccentric cam pulleys are utilized at both ends of the bow. It is to be understood that one of the eccentric pulleys could be replaced by an idler pulley in another modification of the system depicted in these figures. The base cam/power cam device disclosed in U.S. Pat. No. 5,975,067, which I incorporate herein by reference, could be employed as the eccentric pulleys, with the distinction that the base cam and the power cam, which in the patent are continuous, are separated by a shouldered portion which disposes the track in the power cam at a spaced axial distance from the track in the base cam so that the tracks are no longer side by side. The importance of this distinction and the function it achieves will be discussed subsequently. Alternatively, cams of the general nature of those disclosed in U.S. Pat. No. 5,975,067 which include the shouldered portions but not all of the features claimed may be employed. 
     Turning now more particularly to FIGS. 12-14, where like numerals to designate previous components have been employed, the three cable system used, as illustrated in the drawings, consists of the draw string or draw cable  15 , the power cable  54  which has a yoke connection  55  to the ends of the lower axle pin  19  as shown particularly in FIG. 14, and let out/take up cable  56  which has a yoke connection  57  to both ends of the axle pin  18  at the upper end of the bow. 
     The base cam/power cam assembly generally designated  58  is used at the lower end of the bow and a like base cam/power cam assembly is used at the upper end of the bow. In both instances, the base cam/power cam assembly includes the partially elliptical base cam  59  having a pulley track  59   a  for reception of the draw cable  15  and a power cam  60  having a pulley track  60   a  for reception of one of the cables  54  or  56 . The upper eccentric mounts the cable  54 , the terminal lower end of the cable  54   a  attaching to a post  61  projecting laterally from the base cam  59 , as shown particularly in FIG.  15 . The upper base cam/power cam assembly mounts the terminal end of the cable  15  on its post  62  projecting laterally from base cam  59 . The lower end base cam/power cam assembly  59  mounts the cable  56  on its attachment projection  61  and the cable  56  has a yoke connection to both ends of the upper axle pin  18 . 
     In FIGS. 15-17, the power cam  60  is shown as including an end  60   y  abutting a post  60   b  on base cam  59  and an end  60   c  which embraces a tubular post  60   d  on base cam  59  which is journaled on the pulley pin  18 . As previously, the base cam  59  and power cam  60  rotate in unison on the pin  18 . The upper terminal end  15   a  of draw cable  15  has a yoke connection  15   a  to a post  62  fixed on the opposite face of the base cam  59  and the lower terminal end has a similar connection to the base cam  59  of the lower eccentric assembly  58 . Both the base cam  59  and the power cam  60  are fixed to one another to move eccentrically about the pivot post  18  at the upper end of the bow, or  19  at the lower end of the bow. Where previously the base cam  59  and the power cam  60  have been side by side or adjacent to one another, they now are separated by a shoulder or axial projection  63  fixed on the base cam pulley  59 . This projection  63  which extends clockwisely from y to z substantially around power cam  60  in FIG. 16 reduces twisting forces and assures that the base cam/power cam assemblies will lie in vertical alignment. The projection  63  is not necessarily clockwisely continuous and may be sectionalized. Generally speaking, the axial projection of the shoulders  63  will be in the neighborhood of 0.5 to 1.25 inches around a substantive portion of the extent of the power cam  60 . In the lower part of the range, one of the shoulders  63  on the upper and lower eccentric pulleys will normally be at least sufficiently different in projection extent to best maintain cable separation. In the right hand bow depicted the projection  63  at the lower end of the bow will be the longer projection. In a left hander&#39;s bow, this will be reversed. When a sufficiently long shoulder projection in the neighborhood of 0.75 to 1.25 inches is provided, the cable guard rod r shown in FIG. 1 can be eliminated because the projections  63  on the eccentric pulley assemblies  58  hold the cables  56  and  54  sufficiently apart so that they do not touch one another or imperil the arrow feathers when the arrow is released. In the embodiment where an idler pulley is used in place of the upper eccentric, a hub part, of selected axial projection inwardly, may be used to locate the idler pulley track in vertical alignment with the lower eccentric base cam track. 
     The Operation 
     When the draw weight of the bow is adjusted via bolts  31 , the limbs  10  and  11  are free to flex or unflex with respect to bolts  31  slightly because of the slots  24 ,  30 ,  35 , and  12   s.  The inner ends of limbs  10  and  11  are restricted resiliently by walls  34  from all but very limited, flexural movement inwardly. In operation, as the bow string  15  is pulled rearwardly to its position of maximum weight at mid-draw against the resistance of cable system TC, the limbs  10  and  11  will flex or curve in the usual manner and the cups or liners  33  will cushion the return from deflection when the arrow is released and the limbs  10  and  11  recoil. With the cups  32  constructed of a semi-rigid resilient anti-vibration material, the transfer of stresses to the limb seats or pockets and riser is dampened because the upstanding walls of the cups  32  are snugly received by the upstanding walls of the metallic limb seats and limb recoil vibration and noise is isolated. Any tendency of the limb cups  32  to rotate and impose torsional forces is also reduced and dampened because the walls  33  are snugly in engagement with the walls  28 , and walls  29  are snugly in engagement with the walls  34 . The limbs  10  and  11  are not of a thickness to project above the cup walls  33  and  34 . The provision of the washers  42  and the bushings  43  or the synthetic plastic vibration damping cylinder  45  with anti-vibration end caps  47 - 48  further damps the vibration which occurs at the moment of arrow release. The fact that the bow string  15  is in vertically centered relationship results in less torsional force being imposed on the limbs  10  and  11  and the centering of the arrow top to bottom provides greater accuracy in the shot. 
     Method of Construction 
     In constructing the bow, a normal first step is to secure the bow seats  26  to the opposite ends of the riser  12  by means of bolts  25 , with the riser surfaces  12   f  fitting within the bottom recesses  26   b  in cups  26  and the openings  12   s  and  30  in alignment. Next the limb cups  32  are snugly fitted within the limb seats  26 , and the limbs  10  and  11  are inserted with the slots  24  in alignment with the limb cup openings  35  which are aligned with the pocket openings  30 . The anti-vibration members  43  are next inserted in the openings  12   e  with the openings  44  and  46  aligned with openings  12   s,  and caps  47  and  48  are then adhesively secured in position on opposite sides of the riser  12 . With the metallic washer  40  and the anti-vibration washer  42  in place on the bolts  31 , each bolt  31  is extended through the slotted openings  24 ,  35 ,  30  and  12   s  into the bushing opening  34  and threaded into threaded opening  46 . Then, the handle  12   a,  cable guard rod r, pulleys and axles, and the string and tension cable system TC may be installed in the usual manner. 
     The disclosed embodiment is representative of a presently preferred form of the invention, but is intended to be illustrative rather than definitive thereof. The invention is defined in the claims.

Technology Classification (CPC): 8