Bow string cam arrangement for a bow
A dual-cam archery bow with simultaneous power cable take-up and let-out journals. Each cam has power cable journals located on opposite sides of the draw string journal, where at least one of power cable journals is a helical journal.
1 . A bow comprising:
a riser including an up-range side positioned proximate a user and a down-range side positioned proximate a target;
at least one first bow limb attached to the riser and extending at least partially in an up-range direction relative to the up-range side of the riser;
at least one second bow limb attached to the riser and extending at least partially in the up-range direction relative to the up-range side of the riser;
a first cam mounted to the at least one first bow limb and rotatable around a first axis within a first plane of rotation perpendicular to the first axis, the first cam comprising a first draw string journal, a first power cable journal extending in a direction perpendicular to the first plane of rotation, and a second power cable journal extending in a direction perpendicular to the first plane of rotation, wherein the first power cable journal and the second power cable journal each define a path configured to engage a cable, the path at least partially extending at an angle relative to the first plane of rotation;
a second cam mounted to the at least one second bow limb and rotatable around a second axis within a second plane of rotation perpendicular to the second axis, the second cam comprising a second draw string journal, a third power cable journal extending in a direction perpendicular to the second plane of rotation, and a fourth power cable journal extending in a direction perpendicular to the second plane of rotation, wherein the third power cable journal and the fourth power cable journal each define a path configured to engage a cable, the path extending at least partially at an angle relative to the second plane of rotation;
a draw string configured to launch a projectile along a projectile axis, the draw string received in the first and second draw string journals and secured to the first and second cams, wherein the draw string unwinds from the first and second draw string journals as the draw string translates from a released configuration to a drawn configuration, wherein:
in the released configuration, a first portion of the draw string is received in the first draw string journal, a second portion of the draw string is received in the second draw string journal, and a third portion of the draw string extends linearly: (1) between the first cam and the second cam, (2) directly from a down-range side of the first cam, the down-range side of the first cam positioned down-range relative to the first axis and located between the riser and the first axis, and (3) directly from a down-range side of the second cam, the down-range side of the second cam positioned down-range relative to the second axis and located between the riser and the second axis; and
in the drawn configuration, the first portion of the draw string, the second portion of the draw string, and the third portion of the draw string are positioned to the up-range side of the riser; and
a first power cable and a second power cable, the first power cable attached to the first cam and the second cam, the second power cable attached to the first cam and the second cam, wherein a first portion of the first power cable is received in the first power cable journal and a second portion of the first power cable is received in the fourth power cable journal, and wherein a first portion of the second power cable is received in the second power cable journal and a second portion of the second power cable is received in the third power cable journal,
wherein, during operation of the bow as the draw string moves from the released configuration to the drawn configuration, the first portion of the first power cable and the first portion of the second power cable are displaced along the first axis relative to the first plane of rotation of the first draw string journal and the second portion of the first power cable and the second portion of the second power cable are displaced along the second axis relative to the second plane of rotation of the second draw string journal, and
wherein a draw force versus draw distance of the bow is determined at least in part by relative rates of take-up and let-out of the first power cable journal and the second power cable journal.
2 . The bow of claim 1 , wherein during operation of the bow as the draw string moves from the released configuration to the drawn configuration, the first cam and the second cam move continuously inwards towards a center rail of the bow.
3 . The bow of claim 1 wherein, during operation of the bow as the draw string moves from the released configuration to the drawn configuration, the first portion of the first power cable wraps onto the first power cable journal and the first portion of the second power cable wraps onto the third power cable journal to respectively displace the first portion of the first power cable and the first portion of the second power cable along the first and second axes away from the first and second planes of rotation of the first and second draw string journals.
4 . The bow of claim 1 , wherein during operation of the bow as the draw string moves from the released configuration to the drawn configuration, the second portion of the first power cable engages with the second power cable journal and the second portion of the second power cable engages with the fourth power cable journal to displace the second portion of the first power cable and the second portion of the second power cable along the first and second axes relative to the first and second planes of rotation, respectively.
5 . The bow of claim 1 wherein at least the first and third power cable journals extend in a direction perpendicular to the first and second planes of rotation, respectively.
6 . The bow of claim 1 wherein the first and second power cables are wrapped more than about 270 degrees around at least the first and third power cable journals when the bow is in the drawn configuration.
7 . The bow of claim 1 wherein each of the first power cable journal, the second power cable journal, the third power cable journal, and the fourth power cable journal comprise a path that is at least partially helical.
8 . The bow of claim 1 , wherein a distance between the first axis and the second axis is less than 8 inches with the bow in the drawn configuration.
9 . The bow of claim 8 , wherein the first power cable journal and the second power cable journal rotate about a first power cable journal axis that is coaxial with the first axis of the first cam, and wherein the third power cable journal and the fourth power cable journal rotate about a second power cable journal axis that is coaxial with the second axis of the second cam.
10 . The bow of claim 1 , wherein, in the drawn configuration, at least a portion of the draw string is positioned to the up-range side of the riser.
11 . A bow comprising:
a riser including an up-range side positioned proximate a user and a down-range side positioned proximate a target;
at least one first bow limb attached to the riser and extending at least partially in an up-range direction relative to the up-range side of the riser;
at least one second bow limb attached to the riser and extending at least partially in the up-range direction relative to the up-range side of the riser;
a first cam mounted to the at least one first bow limb and rotatable around a first axis within a first plane of rotation perpendicular to the first axis, the first cam comprising a first draw string journal, a first power cable journal extending from the first plane of rotation, and a second power cable journal extending from the first plane of rotation, wherein the first power cable journal and the second power cable journal include a path that is at least partially helical, wherein a draw force versus draw distance of the bow is determined at least in part by relative rates of take-up and let-out of the first power cable journal and the second power cable journal;
a second cam mounted to the at least one second bow limb and rotatable around a second axis within a second plane of rotation perpendicular to the second axis, the second cam comprising a second draw string journal, a third power cable journal extending from the second plane of rotation, and a fourth power cable journal extending from the second plane of rotation, wherein the third and fourth power cable journals include a path that is at least partially helical, wherein the draw force versus draw distance of the bow is determined at least in part by relative rates of take-up and let-out of the third power cable journal and the fourth power cable journal;
a draw string configured to launch a projectile along a projectile axis, the draw string received in the first and second draw string journals and secured to the first and second cams, wherein the draw string unwinds from the first and second draw string journals as it translates from a released configuration to a drawn configuration, wherein:
in the released configuration, a first portion of the draw string is received in the first draw string journal, a second portion of the draw string is received in the second draw string journal, and a third portion of the draw string extends linearly: (1) between the first cam and the second cam, (2) directly from a down-range side of the first cam, the down-range side of the first cam positioned down-range relative to the first axis and located between the riser and the first axis, and (3) directly from a down-range side of the second cam, the down-range side of the second cam positioned down-range relative to the second axis and located between the riser and the second axis; and
in the drawn configuration, the first portion of the draw string, the second portion of the draw string, and the third portion of the draw string are positioned to the up-range side of the riser; and
a first power cable attached to the first cam and received in the first power cable journal; and
a second power cable attached to the second cam and received in the third power cable journal,
wherein, during operation of the bow as the draw string moves from the released configuration to the drawn configuration, the first power cable is displaced along the first axis relative to the first plane of rotation of the first draw string journal and the second power cable is displaced along the second axis relative to the second plane of rotation of the second draw string journal, and
wherein, during operation of the bow as the draw string moves from the released configuration to the drawn configuration, the first axis moves continuously towards the second axis.
12 . The bow of claim 11 wherein, during operation of the bow as the draw string moves from the released configuration to the drawn configuration, the first power cable unwinds from the fourth power cable journal and the second power cable unwinds from the second power cable journal.
13 . The bow of claim 11 , wherein a distance between the first axis and the second axis is less than 8 inches with the bow in the drawn configuration.
14 . The bow of claim 11 , wherein during operation of the bow as the draw string moves from the released configuration to the drawn configuration, the first and second cams rotate and the first power cable journal displaces the first power cable along the first axis relative to the first plane of rotation and the second power cable along the second axis relative to the second plane of rotation.
15 . The bow of claim 11 wherein, during operation of the bow as the draw string moves between the released configuration and the drawn configuration, the first power cable wraps along the path of the first power cable journal and the second power cable wraps along the path of the third power cable journal.
16 . The bow of claim 11 , wherein during operation of the bow as the draw string moves from the drawn configuration to the released configuration, the first power cable and the second power cable wind onto the fourth power cable journal and the second power cable journal, respectively.
17 . The bow of claim 11 wherein, during operation of the bow as the draw string moves from the released configuration to the drawn configuration, the first power cable and the second power cable respectively wrap more than about 270 degrees around the first power cable journal and the third power cable journal.
18 . A bow comprising:
a riser coupled to a center rail and including an up-range side positioned proximate a user and a down-range side positioned proximate a target;
at least one first bow limb attached to the riser and extending at least partially in an up-range direction relative to the up-range side of the riser;
at least one second bow limb attached to the riser and extending at least partially in the up-range direction relative to the up-range side of the riser;
a first cam mounted to the at least one first bow limb and rotatable around a first axis within a first plane of rotation perpendicular to the first axis, the first cam comprising a first draw string journal, a first power cable journal having a first power cable journal axis, and a second power cable journal having a second power cable journal axis, the first power cable journal defining a first path configured to receive a cable, wherein the first power cable journal axis and the second power cable journal axis are coaxial;
a second cam mounted to the at least one second bow limb and rotatable around a second axis within a second plane of rotation, the second cam comprising a second draw string journal, a third power cable journal having a third power cable journal axis, and a fourth power cable journal having a fourth power cable journal axis, the third power cable journal defining a second path configured to receive a cable, wherein the third power cable journal axis and the fourth power cable journal axis are coaxial;
a draw string configured to launch a projectile along a projectile axis, the draw string received in the first and second draw string journals and secured to the first and second cams, wherein the draw string unwinds from the first and second draw string journals as it translates from a released configuration to a drawn configuration, wherein:
in the released configuration, a first portion of the draw string is received in the first draw string journal, a second portion of the draw string is received in the second draw string journal, and a third portion of the draw string extends linearly: (1) between the first cam and the second cam, (2) directly from a down-range side of the first cam, the down-range side of the first cam positioned down-range relative to the first axis and located between the riser and the first axis, and (3) directly from a down-range side of the second cam, the down-range side of the second cam positioned down-range relative to the second axis and located between the riser and the second axis; and
in the drawn configuration, the first portion of the draw string, the second portion of the draw string, and the third portion of the draw string are positioned to the up-range side of the riser;
a first power cable attached to the first cam and received in the first power cable journal; and
a second power cable attached to the second cam and received in the third power cable journal,
wherein the first and third power cable journals comprise a width at least twice a width of the first and second power cables so that, during operation of the bow as the draw string is moved from the released configuration to the drawn configuration, the first and second power cables respectively wrap on the first and third power cable journals along the first and second paths respectively defined by the first power cable journal and the third power cable journal, the first and second paths extending at an angle relative to the first and second planes of rotation, respectively, and
wherein, during operation of the bow as the draw string moves from the released configuration to the drawn configuration, the first cam and the second cam move continuously inwards towards the center rail.
19 . The bow of claim 18 , wherein during operation of the bow as the draw string moves from the released configuration to the drawn configuration, the first and second cables wrap greater than 270 degrees around the first and third power cable journals and are displaced along the first and second axes relative to the first and second planes of rotation of the first and second draw string journals, respectively.