US20150184974A1

US20150184974A1 - Cam Adjustment Mechanism for Compound Bow

Info

Publication number: US20150184974A1
Application number: US14/145,237
Authority: US
Inventors: Roger C. Blahnik
Original assignee: ROGER C BLAHNIK TRUSTEE OF ROGER C BLAHNIK REVOKABLE LIVING TRUST
Current assignee: ROGER C BLAHNIK TRUSTEE OF ROGER C BLAHNIK REVOKABLE LIVING TRUST
Priority date: 2013-12-31
Filing date: 2013-12-31
Publication date: 2015-07-02

Abstract

A cam adjustment mechanism is provided for both single and dual cam bows which enables excess cable length to be removed to re-sync the cams to restore performance of a bow which has experienced degradation due to unequal cable elongation. The cam adjustment mechanism can also be used to tune the bow to the archer's preferred characteristics.

Description

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention is directed to the field of archery. More particularly, the present invention is directed to a cam adjustment mechanism for compound bows.
In existing compound bows, eventually, one of the two power cables will stretch more than the other. This causes the cam rotation to lose sync giving the bow a herky-jerky feel. In addition, this offset cam condition creates a loss of performance (accuracy, arrow velocity, etc.) With existing bows, the only remedy is to take the shop where it is placed on a bow press for cam adjustment and/or cable replacement. This creates down time for the bow and involves significant expense for anyone not owning their own bow press.
It is among the objects of the present invention to produce an OEM bow or a feature which can be added to any conventional bow which will allow the bow owner to make the adjustment themselves, eliminating the difference in effective cable length synching the cams and doing away with the jerkiness of bow operation.
The present invention comprises apparatus for adjusting a degree of cam rotation of a compound bow, the apparatus including cable tensioning means which has a) first pulley means mounted upon a first end of a first arm of the compound bow, the first pulley means having a first peripheral groove for receiving a draw cable and a second peripheral groove for receiving a power cable; b) second pulley means mounted upon a second opposite end of a second arm of the compound bow, the second pulley means having at least a first peripheral groove for receiving the draw cable; c) adjustment means for engaging at least one of the draw cable and the power cable, the adjustment means being repositionable relative to the first and second pulley means to adjust an amount of tension in the engaged cable. For some embodiments, the first pulley means comprises a first and a second independently rotatable cam. The second pulley means includes a second peripheral groove for receiving the power cable and may include a third and a fourth independently rotatable cam.
Typically, the adjustment means comprises at least one roller for engaging at least one of the power cable and the draw cable to alter the degree of rotation the pulley means of the engaged cable. More preferably, the adjustment means engages both the power cable and the draw cable. In some embodiments the adjustment means comprises two rollers, a first roller for engaging the power cable and a second roller for engaging the draw cable. Preferably, the second roller is independently adjustable from the first roller and may be mounted on a common support arm. In at least one embodiment, the common support arm is pivotally mounted with respect to a riser of the bow and rotation of the support arm simultaneously adjusts both the power cable and the draw cable.
In at least one embodiment, the adjustment means comprises first roller means and second roller means. In this/these embodiment(s), the first roller means comprise a first and second rollers engaging one of the power cable and the draw cable and the second roller means comprises a third roller diverting the same cable on an opposite side to deflect that cable between the first and second rollers to take up excess cable length. In yet another embodiment, the adjustment means slides along a rod which is attached to the riser of the compound bow.
Various other features, advantages, and characteristics of the present invention will become apparent after a reading of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiment(s) of the present invention is/are described in conjunction with the associated drawings in which like features are indicated with like reference numerals and in which

FIG. 1A is a side view of a first embodiment of the adjustment device of the present invention shown used with a single cam bow configuration;

FIG. 1B is a side view of the first embodiment in an adjusted position;

FIG. 1C is a bottom view of the unadjusted position of the device corresponding to FIG. 1A;

FIG. 1D is a bottom view of the adjusted position corresponding to FIG. 1B;

FIG. 2A is a side view of a second embodiment of the adjustment mechanism used with a dual cam bow design;

FIG. 2B is a side view of the second embodiment in an alternate, faster position;

FIG. 2C is a side view of an incremental adjuster of the present invention;

FIG. 3 is a side view showing a dual-cam system in which the cams are out of sync;

FIG. 4A is a side view of a FIG. 3 dual-cam which has been synched;

FIG. 4B shows the details of the dual roller adjuster used in the FIG. 4A embodiment;

FIG. 4C shows the rollers adjusted in a manner to sync the cams;

FIG. 5A is a top view of a fourth embodiment of adjuster;

FIG. 5B is a top view of the FIG. 5A adjuster with the cables removed;

FIG. 5C is a front view of the FIG. 5A adjuster indicating how it can be tilted to adjust both cables simultaneously;

FIG. 6A is a front view of a fifth embodiment of adjuster which slides along a rod;

FIG. 6B is a view of the FIG. 6A embodiment showing the bow at full draw;

FIG. 6C is a series of upper and front views of portions of the slide adjuster of this embodiment;

FIG. 7 is a side view of a dual-cam system utilizing a sixth embodiment of adjuster;

FIG. 8 is a side view depicting yet an seventh embodiment of adjuster;

FIG. 9A is a side view of a eighth embodiment of adjuster;

FIG. 9B is a detailed view of the adjuster utilized in FIG. 9A;

FIG. 9C is a side view of the eighth embodiment showing the two rollers adjusted to different positions;

FIG. 10A is a side view of a ninth embodiment which may be retrofit on any bow with the adjustment mechanism simply gripping the cable;

FIG. 10B is a side view of the FIG. 10A adjuster with the adjustment mechanism in use;

FIG. 10C is a detailed close up of the adjuster as positioned in FIG. 10A;

FIG. 10D is a end view of the adjuster as shown in FIG. 10A;

FIG. 10E is a detailed close up of the adjuster as positioned in FIG. 10B; and

FIG. 10F is an end view of the adjuster as shown in FIG. 10B.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

A first embodiment of the cam adjustment mechanism of the present invention is depicted in FIGS. 1A-1D generally at 20. As shown in FIGS. 1A and 1B, cam adjustment mechanism 20 is utilized with a single cam bow configuration as a means to tune the bow, that is, to adjust the distance and force needed to get draw cable 11 to full draw position. As seen in FIGS. 1A-1D, adjustment mechanism 20 comprises a first fixed roller 22 mounted on arm 24 which is attached to a bow riser (not shown) and a second movable roller 26 whose position can be changed by adjusting screw 28 to which it is attached. Fixed roller 22 engages power cable 13 while adjustable roller 26 is shown engaging draw cable 11. It will be understood that the fixed roller 22 and adjustable roller 26 can engage the opposite cables without departing from the scope of the invention. FIG. 1C depicts the unadjusted roller as seen in FIG. 1A while FIG. 1D shows the roller 26 in the position corresponding to that shown in FIG. 1B. It will be understood that by adjusting the position of adjustable roller 26, the distance draw cable 11 that must be moved to get to the full draw position, as well as the draw force necessary, can be adjusted, thereby tuning the bow. FIG. 1A shows a position in which a greater draw length is required; this provides reduced vibration with the downside being slower arrow speed. The position shown in FIG. 1B requires reduced draw length, produces faster arrow speed with a downside of increased vibration. Cam adjustment mechanism 20 of the present invention allows the individual archer to tune her/his bow for individual preferences.
Second embodiment of the cam adjustment mechanism is depicted in FIGS. 2A-2B generally at 20 a. The same two positions shown in FIGS. 1A and 1B are shown here in FIGS. 2A and 2B, respectively. The FIGS. 2A and 2B adjuster with dual rollers (only roller 22 a being shown) has a slot 23 a which permits its clamped position relative to the arm upon which it is mounted to be infinitely varied. While the rollers 22 a and its companion, are mounted on separate axles (or a common axle) to turn independently, they are not independently adjustable. These two rollers engage the two power cables 13 and 13′. The FIG. 2C embodiment shows an incremental slot 23 a′ which reduces the risk of slippage, at the cost of the unlimited adjustment. If both rollers are moved identical amounts, tuning will occur as in the FIG. 1 embodiment. If the distance the two rollers are moved varies, the amount of rotation of the two cams 14 and 15 can be adjusted to accommodate differential cable stretching between the power cables 13 and 13′, which occurs over time.
To emphasize this point, attention is directed to FIG. 3. This figure depicts cams 14 and 15 being out of sync. This problem is addressed in FIGS. 4A-4C where movable roller 26 a is moved from the unadjusted position shown in FIG. 4B to the adjusted position depicted in FIG. 4C by rotating adjustment screw 27 a synching cams 14 and 15.
A fourth embodiment of the cam adjustment mechanism of the present invention is depicted in FIGS. 5A-5C generally at 20 b. In this embodiment, roller 22 b which engages the power cable 13 and roller 26 b which engages power cable 13′, are mounted on bracket 30 b which is secured in position on arm 19 by threaded fastener 12. By loosening fastener 12, bracket 30 b can be tilted which adjusts the tension in both cables 13, 13′ simultaneously.
A fifth embodiment of the cam adjustment mechanism of the present invention is depicted in FIGS. 6A-6C. In this embodiment, adjuster 20 c comprises a slide 22 c that rides along rod 40 c. FIG. 6C-1 shows an upper and front view of the slide 22 c. Slide 22 c has a hole 32 c which allows slide 22 c to fit on rod 40 c and a pin 34 c upon which adjuster 25 c pivots. Adjuster 20 c has a first roller 42 c that receives first cam operating cable 13 for cam 14 and a second roller 44 c that receives cam operating cable 13′ for cam 15. FIG. 6C-2 shows adjuster 25 c which has an arcuate slot 27 c that receives adjustment screw 28 c (FIG. 6C-3). FIGS. 6C-4 show top and front views of the cable adjuster 25 c with cables 13, 13′ attached. FIG. 6C-5 shows cable adjuster 25 c tilted completely to one side while FIG. 6C-6 shows adjuster 25 c tilted to the maximum in the opposite direction. As with the previous embodiments, the primary purpose of cam adjustment 25 c is to permit synchronization of the cams 14, 15 while tuning of the bow and adjusting the draw weight are of secondary importance.
Sixth embodiment is shown in FIG. 7 generally at 20 d. As with the third embodiment, incremental adjuster slot 23 d′ is secured to an arm (not shown) which is secured to the bow riser. First roller 22 d engages first power cable 13 and second roller 26 d engages second power cable 13′. The tension in first power cable 13 is adjusted by repositioning the slot 23 d′ relative to its mounting arm while the tension in second power cable 13′ is adjusted by use of adjustment screw 27 d. As previous embodiments, the primary aim is to utilize the adjustment of rollers 22 d and 26 d sync the cams 14, 15; tuning of the bow is of secondary importance.
Seventh embodiment is shown in FIG. 8 generally at 20 e. In this embodiment, adjuster 20 e comprises an H-shaped support 42 e with dual incrementally slotted mounting arms 23 e and 23 e′ which are attached to the support emanating from the riser (not shown). On the opposing arms 25 e and 25 e′, respectively, of H-shaped support 42 e, are fixedly mounted rollers 22 e and 24 e with adjustable roller 26 e movable relative to center arm 29 e of H-shaped support 42 e using adjustment screw 27 e. First power cable 13 traversed roller 22 e, while second power cable is engaged by three rollers: 22 e's companion roller (tucked behind 22 e mounted for independent rotation) roller 24 e and adjustable roller 26 e. It will be understood that it is within the scope of the present invention for rollers 24 e and 26 e to have sister rollers in the same manner as roller 22 e and that preferably, adjustable roller 26 e is separately adjustable.
Eighth embodiment of the cam adjustment mechanism of the present invention is depicted in FIGS. 9A-C generally at 20 f. In this embodiment, each of the rollers 22 f and 26 f are adjustable by rotation of screw mounts 27 f and 27 f′, respectively. This embodiment allows independent adjustment for each of the two adjustment rollers 22 f, 26 f.
Ninth embodiment of the cam adjustment mechanism of the present invention is depicted in FIGS. 10A-10F generally at 20 g. Cam adjuster 20 g can be retrofit to any existing bow since it does not fixedly mount to the riser or other bow structure. Rather, opposing rollers 22 g and 26 g grip the cable 13 to which it is attached. By adjustably positioning roller 26 g, additional slack may be removed from cable 13 as stretching occurs throughout the life of the bow to maintain cams 14, 15 in sync. As with previous embodiments, adjuster 20 f may be utilized to tune the performance of the bow, as well.
Various changes, alternatives, and modifications will become apparent to a person of ordinary skill in the art after a reading of the foregoing specification. It is intended that all such changes, alternatives, and modifications as fall within the scope of the appended claims be considered part of the present invention.

Claims

I claim:

1. Apparatus for adjusting a degree of cam rotation of a compound bow, the compound bow having a riser with a first upper limb and a second lower limb, said apparatus comprising cable tensioning means including

a) first pulley means mounted upon a first end of the first upper limb of the compound bow, said first pulley means having a first peripheral groove for receiving a draw cable and a second peripheral groove for receiving a power cable;

b) second pulley means mounted upon a second opposite end of the second lower limb of the compound bow, said second pulley means having at least a first peripheral groove for receiving the draw cable;

c) adjustment means for engaging at least one of the draw cable and the power cable, said adjustment means being repositionable relative to said first and second pulley means to adjust an amount of tension in the engaged cable.

2. The apparatus of claim 1 wherein said first pulley means comprises a first and a second independently rotatable cam.

3. The apparatus of claim 1 wherein said second pulley means includes a second peripheral groove for receiving the power cable.

4. The apparatus of claim 3 wherein said second pulley means comprises a third and a fourth independently rotatable cam.

5. The apparatus of claim 1 wherein said adjustment means comprises at least one roller for engaging at least one of the power cable and the draw cable to alter the degree of rotation said pulley means of the engaged cable.

6. The apparatus of claim 5 wherein said adjustment means engages both of the power cable and the draw cable.

7. The apparatus of claim 6 wherein said adjustment means comprises two rollers, a first roller for engaging the power cable and a second roller for engaging the draw cable.

8. The apparatus of claim 7 wherein said second roller is independently adjustable from said first roller.

9. The apparatus of claim 8 wherein said first and said second roller are mounted on a common support arm.

10. The apparatus of claim 9 wherein said common support arm is pivotally mounted with respect to a riser of the bow and rotation of said support arm simultaneously adjusts both the power cable and the draw cable.

11. The apparatus of claim 1 wherein said adjustment means comprises first roller means and second roller means.

12. The apparatus of claim 11 wherein said first roller means comprise a first and second rollers engaging one of the power cable and the draw cable and said second roller means comprises a third roller diverting the same cable on an opposite side to deflect that cable between said first and second rollers to take up excess cable length.

13. The apparatus of claim 1 wherein said adjustment means slides along a rod, said rod being attached to the riser of the compound bow.

14. The apparatus of claim 1 wherein said adjustment means is secured to the compound bow solely by gripping the cable which it adjusts.