The present relates to archery bows, and more specifically, to such bows having: (1) novel poundage adjusters, and/or (2) novel cams with significantly reduced lean and wobble.
Buss Cable: Also known as a power cable. It is this cable which deflects an upper bow limb when a hybrid cam bow is drawn.
Control Cable: This cable deflects the lower limb of a hybrid cam bow when the bow is drawn. This cable also synchronizes the movement of the bow's upper and lower cams.
Poundage: The maximum force required to draw a bow.
Hybrid Cam Bow: One with a control cam at the upper end of the bow and a power cam at the lower end of the bow.
Split Limb Bow: One in which upper and lower limbs each have two spaced apart limb elements. These are also commonly referred to as bows with four limbs, two upper and two lower.
Bow Limb Component: A term used herein to refer to either a solid or split bow limb or toan element of a split bow limb.
Provision is generally made to adjust the poundage of a compound archery bow. This allows the archer to tailor the bow to his particular physical capabilities and the use to which he is putting the bow.
Typically, a screw-type adjuster is employed for this purpose. This approach is disadvantageous in that the person has to keep in mind or guess at the number of turns or other displacement of the adjuster; and this is an unwanted complication, particularly if the adjustment is being made in the field. Also, the prior art poundage adjusters typically alter the geometry of the bow as the poundage adjustment is made by changing the brace height of the bow. Geometrical alterations can significantly, and adversely, affect the performance of the bow.
Prior art bows with screw-type poundage adjusters are disclosed in the following U.S. Pat. No. 4,178,905 to Groner; U.S. Pat. No. 5,464,001 to Peck; U.S. Pat. No. 5,720,267 to Walk; U.S. Pat. No. 6,024,076 to Laborde, et al., and U.S. Pat. No. 6,244,259 to Adkins.
Hsu U.S. Pat. Nos. 5,388,563 and 5,411,008 disclose poundage adjusters which feature an indexing arrangement for facilitating poundage adjustment. However, these mechanisms are specifically designed for recurve bows; and there is nothing even remotely suggesting how they could be used or adapted for compound bow poundage adjustment. At the least, this adaptation would require extensive experimentation and redesign. Furthermore, the Hsu approach requires a locking nut and an Allen wrench for tightening and loosening the nut. This is an unwanted complication because of the additional parts required and one which is not considered suitable for field use because of the ease with which the Allen wrench might be lost or misplaced.
A hybrid compound bow has cam-anchored control and buss cables which time and otherwise control the rotation of the bow's upper and lower cams. In a conventional bow, these cables place unbalanced loads on the cam(s). This causes the bottom cam to lean and wobble as the bow is drawn and as an arrow is subsequently shot from the bow. Such phenomena produce significant and unwanted noise and vibration and a significant and obviously unwanted decrease in the accuracy of the bow. A patent addressing these problems is U.S. Pat. No. 6,659,096 to Nealy, Sr., et al. However, the patented approach is believed to be unnecessarily complicated; and it is designed for use only in single cam bows.
Disclosed herein are novel compound archery bows with novel and decidedly superior poundage adjusters. Also disclosed are equally novel and improved cams with features which significantly reduce, if they do not entirely eliminate, cam lean and wobble.
The compound bows of the present invention have a rigid riser and flexible limbs mounted at their leading ends to the upper and lower ends of the riser. Cams are supported on fixedly positioned axles at the trailing, free ends of the limbs. A bow string and a harness composed of a control cable and a buss cable, all placed under tension, extend between the upper and lower cams, fixing the distance between the cam axles and loading the limb components of the bow.
The poundage of the bow is adjusted by bending each of one or more limb components of the bow over a displaceable fulcrum located between the forward and trailing ends of the limb component. If the fulcrum is displaced outwardly from the centerline of a poundage adjuster axle, the bend in the limb component will become steeper. This increases the load on the limb component and, as a consequence, the force required to draw the bow. Conversely, if the limb component is allowed to relax and move inwardly at the fulcrum, the load on the limb component is decreased; and less force is required to draw the bow.
In one embodiment of the invention a rotatable, stepped, axle-supported poundage adjustment cam is fixedly mounted to the riser of the bow at the location of the fulcrum by a complementary cam shaft is advanced to move the fulcrum outwardly and increase the bend in the limb; and the tendency of the limb to relax when the cam is backed off allows the fulcrum to move inwardly and decrease the bend in the limb. As discussed above, these outward and inward displacements of the fulcrum respectively increase and decrease the poundage of the bow.
The cam steps are flats disposed seriatim around the exposed surface of the cam and contactable with the limb. Successive flats are located at incrementally increasing distances from the cam's fixed axis of rotation. Consequently, as the cam is rotatably advanced, the distance of the limb from the axial centerline of the cam axle is increased in incremental steps with corresponding increases in the bend in and load on the limb and, consequently, the poundage of the bow. Backing off the cam stepwise decreases the bend in the limb in predetermined increments with corresponding decreases in the load on the limb and the poundage of the bow.
Because the steps are flat and because the limb is biased against the active step, that step positively engages the facing surface of the limb and keeps the adjustment from shifting without the use of locking nuts or other complicating components.
Integrated with the poundage adjuster cam is a user-manipulatable knob. Indices on this knob allow the person making the poundage adjustment to easily and readily view the adjustment that has been made.
Because the timing and geometry of a bow with poundage adjusters of the present invention remain essentially unchanged as the bow poundage is adjusted, accuracy is not degraded by changing the bow poundage. Also, the novel poundage adjustment systems disclosed herein allow one to independently adjust all of the limbs or limb elements of a compound bow; and the bow does not need to be retuned after a poundage adjustment.
Optionally, the two poundage adjusters in a pair of such adjusters can be made to operate in unison if one wishes.
The novel poundage adjusters are adaptable to a variety of solid and split limb compound bows and solid and split limb cross bows including, without limitation, binary cam, hybrid cam, and solo (single) cam compound and cross bows.
The poundage adjusters are user friendly, light in weight, and simple. The importance of these advantages is self-evident.
Other preferred embodiments of the invention employ a variable radius cam and a cam-associated locking pin or spring-loaded detent or the like to shift the fulcrum about which the limb is bent. In still other preferred embodiment of the invention, the cam mechanism is located at that forward end of the limb where it is attached to the bow riser; and a separate fulcrum is disposed at a location between the forward and trailing ends of the bow.
In each case bow setting indicia are provided. These allow one to easily determine the poundage to which a limb or limb element has been set. In contrast, the prior art screw type poundage adjusters require one to count the number of turns of the screw; and this burdensome, particularly in the field.
Cams which can be used to great advantage not only in bows of the character disclosed herein, but in compound bows and cross bows in general are also disclosed herein. In one respect these cams are improvements of the solo cam disclosed in U.S. Pat. No. 5,505,185 to Miller.
Conventionally, the buss and control cables of a compound bow are both located on the same side of the cam(s) over which they run. Cams set up in this manner tend to lean and wobble as the bow is drawn and as an arrow is then shot from the bow. Lean and wobble increase noise and vibration and significantly detract from the accuracy of the bow.
A cam embodying the principles of the present invention is constructed such that the control and buss cables run on opposite sides of the cam wheel. This equalizes the loads on the cam axle, significantly reducing cam lean and wobble. That in turn reduces noise and vibration and promotes the accuracy of the bow in which the cam is installed.
Preferably, one or more spiral cable or string tracks are provided to keep the control cable, buss cable, and/or bow string out of contact with the sharp cam wheel edge as the bow is drawn and to offsets the changing loads on the cam axle generated as the bow is drawn. To best accomplish the latter objective, the cam track may spiral outwardly or spiral inwardly or have both inwardly and outwardly spiral segments which come into play during different parts of the draw.
Also preferred, and located on the buss cable side of the cam, are a cable-wide gap through which the buss cable runs and an angled ramp separated by a gap from the buss cable side of the cam wheel. The ramp guides the buss cable into the gap, thereby holding the buss cable against the buss cable side of the cam wheel as the bow is drawn. This straightens the cam wheel and/or keeps it from leaning during the draw, making a still further significant contribution to noise and vibration reduction and to the accuracy of the bow.
An option is to use a large radius component on the buss cable side of the bow instead of the above-described ramp to guide the buss cable as the bow is drawn.
An optional cable guide system mounted to the riser of the bow a short distance above the bottom cam can be employed to keep the control cable out of contact with the control cable side of the cam as the bow is drawn and an arrow is shot, further contributing to noise and vibration reduction and accuracy.
Other significant features and advantages of the present invention will be apparent to the reader from the foregoing and the appended claims and from the accompanying drawings taken in conjunction with the detailed description of the invention.
Referring now to the drawings,
Rotatable, axle-supported cams 52 and 54 are mounted to the trailing ends (or tips) 56 and 58 of limbs 44 and 46. Control and buss cables respectively identified by reference characters 60 and 62 and a bow string 64 are strung between upper and lower cams 52 and 54, control cable 60 and buss cable 62 being trained through a riser-mounted cable slide 65a mounted on a guide rod 65b located approximately midway between the upper and lower ends 74 and 76 of riser 42.
It is very advantageous for the archer to be able to adjust the poundage of a compound bow such as exemplary bow 40. To this end, bow 40 is equipped with a pair of novel poundage adjusters 66 and 67 mounted to the upper end 74 of riser 42 (see
Referring again to the drawings, only the upper poundage adjusters 66 and 67 of the
Turning next to
A poundage adjustment knob 82 which is typically an integral part of the same component as fulcrum 70 is provided for rotating fulcrum 70; and a poundage adjustment knob 83 of the same character is provided for rotating fulcrum 81.
The two poundage adjustment fulcrums 70 and 81 are of like character. Accordingly, only fulcrum 70 will be described in detail herein.
As best shown in
The sixth flat step 84-6 is a transition flat between the lowest step 84-1 and the highest step 84-5; that is, between the steps closest to and furthest from axis of rotation 86. This flat is not otherwise employed to adjust the poundage of bow 40.
The under side 88 of upper bow limb element 79 is contacted by a user-selected one of the five-poundage adjustment cam steps 84-1-84-5 rotated into engagement with limb side 88 using knob 82.
As limb element 44b is constrained at its forward end 47a by pocket 48b and at its trailing end 56 by bow string 64, control cable 60, and buss cable 62, the limb is bent around fulcrum 70 to a degree determined by the particular flat 84 in contact with the lower side 88 of bow limb element 44b. The degree of bend is increased as successive flats 84 are rotated into contact with the under side 88 of the bow limb element. As the bend in limb element 44b is increased, the force tending to restore the limb element toward an unflexed or rest configuration is increased. This translates into the force required to draw the bow, i.e., into an increase in the poundage of the bow.
As shown in
Typically, bringing successive cam steps 84 into contact with limb element 79 will increase or decrease the poundage of the bow by two pounds. Again, however, there is nothing critical in this particular parameter; it may also accordingly be varied as desired.
In conjunction with the foregoing, it will also be appreciated that the relatively large area of contact between the active flat 84 of fulcrum 70 and the lower side 88 of limb element 44b forced against that step by the stress in that limb element (see arrow 90 in
Fulcrum 81 similarly acts on the second element 44a of upper limb 44 and bends that element to a degree selected by the rotation of control knob 83. The two elements of lower split bow limb 46 can similarly be independently bent to the wanted degree by the fulcrums (not shown) at the bottom of bow 40. That each of the four limb elements can be independently adjusted is a huge advantage. It allows all four split limb elements to be set with precision to the same poundage or to selected different poundages if that is wanted.
Poundage adjusters employing the principles of the present invention and having the advantages thereof may differ considerably in appearance and construction from the exemplary poundage adjusters 66, 67, and 68 described above in conjunction with
Limb element 44b is bent over fulcrum 102 to a user-selected extent to provide the wanted bow poundage. Specifically, in this embodiment of the invention, the active cam step 84 of poundage adjuster 66 pushes down on the leading tip or end 47a of limb element 44b as indicated by arrow 104 with a force determined by the distance that the active cam step is spaced from the axial centerline (axis of rotation) 86 of the adjuster. This produces a corresponding bend in limb element 44b about fulcrum 102 and, as a consequence, the wanted bow poundage. Again, force applied to limb tip 47a in the arrow 104 direction with the limb under load locks poundage adjuster 66 against rotation, making the use of complicating, additional components for this purpose unnecessary.
To set the bow poundage, lobe 124 is rotated until an appropriate segment of lobe 124 corresponding to the wanted bow poundage engages the bottom side 88 of limb element 44b. A user-manipulatable knob 127 integrated into a single component with lobe 124 is utilized to rotate the lobe until the wanted lobe segment comes into contact with the lower side 88 of limb element 44b.
Numerals 1 through 5 spaced around knob 127 allow the person setting the bow poundage to ascertain the segment of the lobe that is in contact with bow surface 88 and, as a consequence, the poundage to which the bow is set.
In this embodiment of the invention, a set 128 of apertures 128-1-128-5 is formed in adjuster knob 127. A locking pin 130 installed through the aperture 128 in knob 127 corresponding to the selected bow poundage indicator 1-5 and extending into a complementary aperture (not shown) in riser 42 locks lobe cam 124 against rotation, positively maintaining the cam in the position to which it has been rotated.
In a manner akin to that discussed above in conjunction with bow 120, lobe cam 152 is rotated by an operator-manipulatable poundage adjustment knob 161 integrated with lobe cam 152 to bring a segment of the lobe corresponding to a desired bow poundage setting into contact with the bottom or lower side 88 of limb element 44b. Though not shown in
Cam lobe 152 is locked into the position corresponding to the selected poundage setting by a locking pin 162 (see
Step cam 184 is integral with the inner side 186 of a user-manipulatable poundage adjustment actuator 188. The actuator is rotatably supported on an axle 190 from the upper end 74 of riser 42 with the cam bearing against the lower surface 88 of bow limb 44.
Numerals 1-6 spaced at intervals corresponding to incremental and successively higher poundage settings around the periphery 194 of poundage adjustment actuator 182 allow the person setting the poundage or making an adjustment to easily, visually ascertain the setting which has been selected. The flat surface engagement between limb 44 and the active cam step effectively locks the cam in place at the selected setting.
As stated above, poundage adjusters embodying the principles of the present invention provide the same benefits and advantages when used in compound cross bows as they do when used in hybrid cam compound bows. A split limb, compound cross bow thus equipped is illustrated in
Step cam poundage adjusters 240 and 241 are mounted to the right-hand end 226 of rigid frame 216, and poundage adjusters 242 and 243 of the same character as poundage adjusters 66, 67, and 68 are mounted to the riser left-hand end 228, all in the same manner that poundage adjusters 66, 67, and 68 are mounted to riser 42 of the compound bow 40, again at locations between the leading and trailing ends 218 and 236 of limb 222 and the leading and trailing ends 218 and 238 of limb 224. Poundage adjusters 240-243 may be essentially identical to the poundage adjuster 66 described in detail above with reference to
Other of the several poundage adjustment mechanisms disclosed herein can be employed instead of a step cam poundage adjuster like poundage adjuster 66 as can still other cams employing the principles of the present invention.
It was also pointed out above that there is disclosed herein a novel, improved cam which can be employed to advantage in hybrid cam bows to minimize cam lean and wobble as a bow equipped with it is drawn and as an arrow is subsequently shot from the bow. In one respect, the cam is an improvement on the cam disclosed in U.S. patent to Miller.
It is common, in hybrid cam bow construction, for the control and buss cables to be anchored to the lower cam on the same side of the cam wheel. It has now been discovered that the cam lean and wobble and the noise and vibration attributable to this arrangement can be significantly minimized by relocating the buss cable to the opposite side of the cam wheel from the control cable. This innovation balances the loads on the cam axle, which significantly reduces cam lean and wobble.
A cam of the character just described is shown in
Cam 400 includes an elliptical, asymmetrically supported cam wheel 404, with a control cable side 406 and a buss cable side 408. A string track 410 is formed around the periphery of cam wheel 404. Bow string 64 runs in this cam track.
Control cable and buss cable elements 412 and 414 are part of or fixed to cam wheel 404 on the control and buss cable sides 406 and 408 of the cam wheel. A control cable track 416 is provided in the periphery of control cable element 412, and a buss cable track 418 is formed in the periphery of buss cable element 414.
Control cable 60 rides in the track 416 of control cable element 412, and buss cable 62 rides in the track 418 of buss cable element 414 as bow 40 is drawn by pulling bow string 64 in the direction indicated by arrow 419 in
Running the control and buss cable 60 and 62 in tracks 416 and 418 keeps the cables from moving side-to-side as bow 40 is drawn.
Control cable guide track 416 has an outwardly spiraling configuration as shown in
An angled ramp 420 is mounted on the buss cable side 408 of cam wheel 404 with a gap 421 between the cam wheel and the ramp. At the end part of the draw, ramp 420 pushes the buss cable against the buss cable side 408 of cam wheel 404. This helps to keep the cam from leaning and pushes the cam back into alignment if it does lean.
Control cable 60 runs in a shallow, typically Teflon lined depression 430 formed in the guide rod 431 of a guide system 432 which also includes a bumper 433. The control cable is pushed into line by the guide rod. The guide rod is mounted to and extends rearwardly from riser 42 at a location above bottom cam 400 and below the guide rod 65b and cable slide 65a. This further constrains the control cable to in-line movement, additionally reducing noise and vibration and promoting the accuracy of bow 40. Bow string 60 rests on the rear end of bumper 433.
Elastomeric vibration dampeners can advantageously mounted to the limbs of the several bows disclosed herein to dampen vibrations generated as an arrow is shot from the bow. This contributes significantly to the accuracy of the bow. One such vibration dampener is shown in
The principles of the present invention may be embodied in forms other than those specifically disclosed herein. For example, a set of limb engageable poundage adjusters of different heights may be used instead of the herein disclosed rotating cam adjusters to adjust bow poundage. Therefore, the present embodiments are to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced herein.
The benefit of the filing date of provisional application No. 61/284,715 filed 23 Dec. 2009 is claimed.
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