Balanced pulley assembly for compound archery bows, and bows incorporating that assembly
View Patent ↗A compound bow includes a first and second pulley, each of which is operative, when the bow is drawn, to unwind a portion of a bow string from a bow string groove and to take up a portion of a bow cable so as to decrease its effective length. At least one of the pulleys includes a cable controller which operates to modify the rate at which the effective length of the bow cable is decreasing so that during an initial portion of the draw of the bow, the rate is greater than it would be in the absence of the controller, and during a second portion of the draw, the rate is less than it would be in the absence of the controller. Use of the controller provides a bow which has an inherently balanced draw.
1. A compound archery bow comprising:
a substantially rigid riser;
a first resilient bow limb extending from a first end portion of the riser;
a second resilient bow limb extending from a second end portion of the riser;
a first pulley member connected to the first bow limb and rotatable relative to the first bow limb around a first rotation axis, which first pulley member includes a first draw cable journal and a power cable take-up mechanism;
a second pulley member connected to the second bow limb and rotatable relative to the second bow limb around a second rotation axis, which second pulley member includes a second draw cable journal and a power cable let-out mechanism;
a draw cable engaged with the first and second draw cable journals and arranged to rotate the first and second pulley members as the bow is drawn and the draw cable is let out from the first and second draw cable journals; and
a power cable (i) engaged to be taken up by the power cable take-up mechanism as the bow is drawn and the first pulley member rotates and (ii) engaged to be let out by the power cable let-out mechanism as the bow is drawn and the second pulley member rotates, wherein:
the power cable let-out mechanism comprises paired let-out members disposed on opposite sides of the second bow limb; and the power cable is engaged with the paired let-out members.
2. The bow of claim 1 wherein the power cable is engaged with the power cable let-out mechanism in a split cable arrangement wherein corresponding split end segments of the power cable are engaged with the paired let-out members on opposite sides of the second bow limb.
3. The bow of claim 1 wherein the power cable is engaged with the power cable let-out mechanism in a split cable arrangement engaged with the paired let-out members on opposite sides of the second bow limb.
4. The bow of claim 1 wherein the paired let-out members comprise a pair of power cable anchors that are eccentrically positioned relative to the second rotation axis so as to let out the power cable over at least a latter portion of drawing the bow.
5. The bow of claim 4 wherein the pair of power cable anchors are eccentrically positioned relative to the second rotation axis so as to take up the power cable over an initial portion of drawing the bow.
6. The bow of claim 1 wherein:
the first pulley member includes a second power cable let-out mechanism;
the second pulley member includes a second power cable take-up mechanism;
the bow further comprises a second power cable (i) engaged to be taken up by the second power cable take-up mechanism as the bow is drawn and the second pulley member rotates and (ii) engaged to be let out by the second power cable let-out mechanism as the bow is drawn and the first pulley member rotates;
the second power cable let-out mechanism comprises corresponding paired let-out members disposed on opposite sides of the first bow limb; and
the second power cable is engaged with the paired let-out members.
7. The bow of claim 6 wherein the first and second pulley members are substantially identical or substantial mirror images of one another.
8. The bow of claim 6 wherein the second power cable is engaged with the second power cable let-out mechanism in a split cable arrangement engaged on opposite sides of the first bow limb with the paired let-out members.
9. The bow of claim 1 wherein the first and second pulley members are arranged so as to avoid 100% let-off of the draw force or so as to prevent cocking of the bow.
10. The bow of claim 1 wherein the first pulley member is arranged so that a ratio between a lever arm of the power cable take-up mechanism and a lever arm of the power cable let-out mechanism remains greater than 1:1 during let-out of the power cable.
11. The bow of claim 1 wherein the power cable take-up mechanism comprises a power cable take-up journal.
12. A compound archery bow comprising:
a substantially rigid riser;
a first resilient bow limb extending from a first end portion of the riser;
a second resilient bow limb extending from a second end portion of the riser;
a first pulley member connected to the first bow limb and rotatable relative to the first bow limb around a first rotation axis, which first pulley member includes a first draw cable journal and a power cable take-up mechanism;
a second pulley member connected to the second bow limb and rotatable relative to the second bow limb around a second rotation axis, which second pulley member includes a second draw cable journal and a power cable let-out mechanism;
a draw cable engaged with the first and second draw cable journals and arranged to rotate the first and second pulley members as the bow is drawn and the draw cable is let out from the first and second draw cable journals; and
a power cable (i) engaged to be taken up by the power cable take-up mechanism as the bow is drawn and the first pulley member rotates and (ii) engaged to be let out by the power cable let-out mechanism as the bow is drawn and the second pulley member rotates, wherein:
the power cable let-out mechanism comprises paired let-out members disposed on opposite sides of the second bow limb; and the power cable is engaged with the power cable let-out mechanism in a split cable arrangement engaged with the paired let-out members on opposite sides of the second bow limb.
13. The bow of claim 12 wherein the power cable is engaged with the power cable let-out mechanism in a split cable arrangement wherein corresponding split end segments of the power cable are engaged with the paired let-out members on opposite sides of the second bow limb.
14. The bow of claim 12 wherein the paired let-out members comprise a pair of power cable anchors that are eccentrically positioned relative to the second rotation axis so as to let out the power cable over at least a latter portion of drawing the bow.
15. The bow of claim 14 wherein the pair of power cable anchors are eccentrically positioned relative to the second rotation axis so as to take up the power cable over an initial portion of drawing the bow.
16. The bow of claim 12 wherein:
the first pulley member includes a second power cable let-out mechanism;
the second pulley member includes a second power cable take-up mechanism;
the bow further comprises a second power cable (i) engaged to be taken up by the second power cable take-up mechanism as the bow is drawn and the second pulley member rotates and (ii) engaged to be let out by the second power cable let-out mechanism as the bow is drawn and the first pulley member rotates;
the second power cable let-out mechanism comprises corresponding paired let-out members disposed on opposite sides of the first bow limb; and
the second power cable is engaged with the second power cable let-out mechanism in a split cable arrangement engaged on opposite sides of the first bow limb with the paired let-out members.
17. The bow of claim 16 wherein the first and second pulley members are substantially identical or substantial mirror images of one another.
18. The bow of claim 12 wherein the first and second pulley members are arranged so as to avoid 100% let-off of the draw force or so as to prevent cocking of the bow.
19. The bow of claim 12 wherein the first pulley member is arranged so that a ratio between a lever arm of the power cable take-up mechanism and a lever arm of the power cable let-out mechanism remains greater than 1:1 during let-out of the power cable.