Crossbow with Pulleys that Rotate Around Stationary Axes
A crossbow including a frame with a riser and a center trail. First and second flexible limbs are attached to the riser. A draw string is received in string guide journals in first and second cams rotatably attached to the frame. The draw string unwinds from the string guide journals as it translates between a released configuration and a drawn configuration. The first and second cams include at least first and second power cable take-up journals, respectively. At least first and second power cables are attached to the first and second limbs and received in the first and second power cable take-up journals, respectively. As the crossbow is drawn from the released configuration to the drawn configuration the first and second power cables wrap onto the respective first and second power cable take-up journals.
The present application is also a continuation of U.S. patent Ser. No. 15/782,259, entitled Crossbow with Pulleys that Rotate Around Stationary Axes, filed Oct. 12, 2017, which claims the benefit of U.S. Provisional Application Ser. No. 62/441,618, entitled Crossbow with Pulleys that Rotate Around Stationary Axes, filed Jan. 3, 2017.
The present application is also a continuation of U.S. patent Ser. No. 15/782,259, entitled Crossbow with Pulleys that Rotate Around Stationary Axes, filed Oct. 12, 2017, which is a continuation-in-part of patent Ser. No. 15/443,769 entitled Crossbow, filed Feb. 15, 2017, which is a continuation-in-part of U.S. patent Ser. No. 15/294,993 entitled String Guide for a Bow, filed Oct. 17, 2016, which is a continuation-in-part of U.S. patent Ser. No. 15/098,537 entitled Crossbow, filed Apr. 14, 2016 (issued as U.S. Pat. No. 9,494,379), which claims the benefit of U.S. Provisional Application Ser. No. 62/244,932, filed Oct. 22, 2015 and is also a continuation-in-part of U.S. patent Ser. No. 14/107,058 entitled String Guide System for a Bow, filed Dec. 16, 2013 (issued as U.S. Pat. No. 9,354,015), the entire disclosures of which are hereby incorporated by reference.
FIELD OF THE INVENTIONThe present disclosure is directed to a crossbow with pulleys that rotate around stationary axes that are fixed relative to the center rail and the riser. Power cables connect the limbs to the pulleys such that as the crossbow is drawn from the released configuration to the drawn configuration the power cables wrap onto the respective power cable take-up journals. Only the draw string crosses the center rail.
BACKGROUND OF THE INVENTIONBows have been used for many years as a weapon for hunting and target shooting. More advanced bows include cams that increase the mechanical advantage associated with the draw of the bowstring. The cams arc configured to yield a decrease in draw force near full draw. Such cams preferably use power cables that load the bow limbs. Power cables can also be used to synchronize rotation of the cams, such as disclosed in U.S. Pat. No. 7,305,979 (Yehle).
With conventional bows and crossbows the draw string is typically pulled away from the generally concave area between the limbs and away from the riser and limbs. This design limits the power stroke for bows and crossbows.
In order to increase the power stroke, the draw string can be positioned on the down-range side of the string guides so that the draw string unrolls between the string guides toward the user as the bow as the bow is drawn, such as illustrated in U.S. Pat. Nos. 7,836,871 (Kempf) and 7,328,693 (Kempf). One drawback of this configuration is that the power cables can limit the rotation of the cams to about 270 degrees. In order to increase the length of the power stroke, the diameter of the pulleys needs to be increased. Increasing the size of the pulleys results in a larger and less usable bow.
As the draw string 30 is moved from released configuration 32 of
Further rotation of the string guides 22 in the direction 36 causes the power cables 20 to contact the power cable take-up journal, stopping rotation of the cam. The first attachment points 24 may also contact the power cables 20 at the locations 38A, 38B (“38”), preventing further rotation in the direction 36. As a result, rotation of the string guides 22 is limited to about 270 degrees, reducing the length 40 of the power stroke.
BRIEF SUMMARY OF THE INVENTIONThe present disclosure is directed to a crossbow with pulleys rotatably attached to the center rail or the riser. Power cables connect the limbs to the pulleys such that only the draw string translates between a released configuration and a drawn configuration the power cables wrap onto power cable take-up journals on the pulleys.
In one embodiment the crossbow includes a frame with a riser and a center rail. First and second, flexible limbs are attached to the riser. A draw string is received in string guide journals in first and second cams rotatably attached to the frame. The draw string unwinds from the string guide journals as it translates between a released configuration and a drawn configuration. The first and second cams include at least first and second power cable take-up journals, respectively. At least first and second power cables are attached to the first and second limbs and received in the first and second power cable take-up journals, respectively. As the crossbow is drawn from the released configuration to the drawn configuration the first and second power cables wrap onto the respective first and second power cable take-up journals.
The first and second cams can be mounted to the riser or the center rail. The first and second axes around which the first and second cams rotate are stationary with respect to the frame. The separation between first and second axes is preferably less than about 5 inches, and more preferably less than about 4 inches.
The first and second cams preferably rotate between about 270 degrees to about 330 degrees when the crossbow is drawn from the released configuration to the drawn configuration. In another embodiment, the first and second cams rotate between about 300 degrees to about 360 degrees when the crossbow is drawn from the released configuration to the drawn configuration. In yet another embodiment, the first and second cams rotate more than about 360 degrees when the crossbow is drawn from the released configuration to the drawn configuration. The first and second power cables do not cross over the center rail. The draw string in the drawn configuration preferably has an included angle of less than about 15 degrees.
In one embodiment, the crossbow includes a string carrier that slides along the center rail to engage with the draw string in the released configuration and to a retracted position that locates the draw string in the drawn configuration. A retaining mechanism retains the string carrier in the retracted position and the draw string in the drawn configuration. A trigger releases the draw string from the string carrier to fire the crossbow when the string carrier is in the retracted position.
In one embodiment, the string carrier is captured by the center rail during movement of the string carrier between the release configuration and the drawn configuration. The string carrier is preferably constrained to move in a single degree of freedom along the center rail between the release configuration and the drawn configuration. In one embodiment, the retaining mechanism is a cocking mechanism that moves the string carrier along the center rail to the retracted position and the draw string to the drawn configuration. In another embodiment, at least one cocking rope configured to engage with the string carrier is used to retract the string carrier and the draw string to the drawn configuration.
The present disclosure is also directed to a crossbow including a frame with a riser and a center rail. First and second flexible limbs are attached to the riser. A first cam is mounted to the frame and is rotatable around a first axis. The first cam includes a first draw string journal having a first plane of rotation perpendicular to the first axis, and at least one first power cable take-up journal. A second cam is mounted to the frame and is rotatable around a second axis. The second cam includes a second draw string journal having a second plane of rotation perpendicular to the second axis, and at least one second power cable take-up journal. A draw string is received in the first and second string guide journals and secured to the first and second cams. The draw string unwinds from the first and second string guide journals as it translates from a released configuration to a drawn configuration. At least first and second power cables are attached to the first and second limbs and received in the first and second power cable take-up journals, respectively. As the crossbow is drawn from the released configuration to the drawn configuration the first and second power cables wrap, onto the respective first and second power cable take-up journals.
The present disclosure is also directed to a crossbow including a frame with a riser and a center rail. First and second flexible limbs are attached to the riser. A first cam is mounted to the frame and is rotatable around a first axis. The first cam includes a first draw string journal having a first plane of rotation perpendicular to the first axis, a first upper power cable take-up journal extending in a direction perpendicular to the first plane of rotation of the first draw string journal, and a first lower power cable take-up journal extending in an opposite direction perpendicular to the first plane of rotation. A second cam is mounted to the frame and is rotatable around a second axis. The second cam includes a second draw string journal having a second plane of rotation perpendicular to the second axis, a second upper power cable take-up journal extending in a direction perpendicular to the second plane of rotation of the second draw string journal, and a second lower power cable take-up journal extending in an opposite direction perpendicular to the second plane of rotation. A draw string is received in the first and second string guide journals and secured to the first and second cams. The draw string unwinds from the first and second string guide journals as it translates from a released configuration to a drawn configuration. First upper and lower power cables are attached to the first limb and received in the upper and lower power cable take-up journals on the first cam. Second upper and lower power cables are attached to, the second limb and received in the upper and lower power cable, take-up journals on the second cam. The first and second power cables do not cross over the center rail.
In one embodiment, as the crossbow is drawn from the released configuration to the drawn configuration the upper and lower power cables wrap onto the respective upper and lower power cable take-up journals and are displaced along the first and second axes away from the first and second planes of rotation of the first and second draw string journals.
The present disclosure is also directed to a method of assembling a crossbow. The method includes providing a frame with a riser and a center rail. At least first and second flexible limbs are attached to the riser. A draw string is located in string guide journals on first and second cams rotatable attached to the frame, such that the draw string unwinds from the string guide journals as it translates between a released configuration and a drawn configuration. At least first and second power cables are attached to the first and second, limbs and the first and second cams, respectively, such that as the crossbow is drawn from the released configuration to the drawn configuration the first and second power cables wrap onto first and second power cable take-up journals on the first and second cams, respectively.
In the reverse draw configuration 92 the draw string 114 is located adjacent down-range side 94 of the string guide system 70 when in the released configuration 116. In the released configuration 116 of
As illustrated in
The string guides 104 each include one or more grooves, channels or journals located between two flanges around at least a portion of its circumference that guides a flexible member, such as a rope, string, belt, chain, and the like. The string guides can be cams or pulleys with a variety of round and non-round shapes. The axis of rotation can be located concentrically or eccentrically relative to the string guides. The power cables and draw strings can be any elongated flexible member, such as woven and non-woven filaments of synthetic or natural materials, cables, belts, chains, and the like.
As the first attachment points 106 rotate in direction 120, the power cables 102 are wrapped onto cams 126A, 126B (“126”) with helical journals 122A, 122B (“122”), preferably located at the respective axles 110. The helical journals 122 take up excess slack in the power cables 102 resulting from the string guides 104 moving toward each other in direction 124 as the axles 110 move toward each other.
The helical journals 122 serve to displace the power cables 102 away from the string guides 104, so the first attachment points 106 do not contact the power cables 102 while the bow is being drawn (see
As a result, the power stroke 132 is extended. In the illustrated embodiment, the power stroke 132 can be increased by at least 25%, and preferably by 40% or more, without changing the diameter of the string guides 104. The power stroke 132 can be in the range of about 8 inches to about 20 inches. The present disclosure permits crossbows that generate kinetic energy of greater than 70 ft.-lbs. of energy with a power stroke of about 8 inches to about 15 inches. In another embodiment, the present disclosure permits a crossbow that generates kinetic energy of greater than 125 ft.-lbs. of energy with a power stroke of about 10 inches to about 15 inches.
In some embodiments, the geometric profiles of the draw string journals 130 and the helical journals 122 contribute to let-off at full draw. A more detailed discussion of cams suitable for use in bows is provided in U.S. Pat. No. 7,305,979 (Yehle), which is hereby incorporated by reference.
Draw string 162 is received in respective draw string journals (see e.g.,
First power cable 168A is secured to the first string guide 158A at first attachment point 170A and engages with a power cable take-up with a helical journal 172A (see
Second power cable 168B is secured to the second string guide 158B at first attachment point 170B and engages with a power cable take-up with a helical journal 172B (see
Draw string 314 extends between first and second string guides 316A, 316B (“316”). In the illustrated embodiment, the string guide 316A is substantially as shown in
The first string guide 316A is mounted to the first bow limb 312A and is rotatable around a first axis 318A. The first string guide 316A includes a first draw string journal 320A and a first power cable take-up journal 322A, both of which are oriented generally perpendicular to the first axis 318A. (See e.g.,
The second string guide 316B is mounted to the second bow limb 312A and rotatable around a second axis 318B. The second string guide 316B includes a second draw string journal 320B oriented generally perpendicular to the second axis 318B.
The draw string 314 is received in the first and second draw string journals 320A, 320B and is secured to the first string guide 316A at first attachment point 324. The draw string extends adjacent to the down-range side 306 to the second string guide 316B, wraps around the second string guide 316B, and is attached at the first axis 318A.
Power cable 324 is attached to the string guide 316A at attachment point 326. See
The string guides 366 are mounted to the bow limb 362 and are rotatable around first and second axis 368A, 368B (“368”), respectively. The string guides 366 include first and second draw string journals 370A, 370B (“370”) and first and second power cable take-up journals 372A, 372B (“372”), both of which are oriented generally perpendicular to the axes 368, respectively. (See e.g.,
The draw string 364 is received in the draw string journals 370 and is secured to the string guides 316 at first and second attachment points 375A, 375B (“325”).
Power cables 374 are attached to the string guides 316 at attachment points 376A, 376B (“376”). See
In the illustrated embodiment, power cables wrap 374 onto the power cable take-up journal 372 and translates along the power cable take-up journals 372 away from the draw string journals 370 as the bow 350 is drawn from the released configuration 378 to the drawn configuration (see
The string guides disclosed herein can be used with a variety of bows and crossbows, including those disclosed in commonly assigned U.S. patent application Ser. No. 13/799,518, entitled Energy Storage Device for a Bow, filed Mar. 13, 2013 and Ser. No. 14/071,723, entitled DeCocking Mechanism for a Bow, filed Nov. 5, 2013, both of which are hereby incorporated by reference.
Draw string 501 is retracted to the drawn configuration 405 shown in
When in the drawn configuration 405 tension forces 409A, 409B on the draw string 501 on opposite sides of the string carrier 480 are substantially the same, resulting in increased accuracy. In one embodiment, tension force 409A is the same as tension force 409B within less than about 1.0%, and more preferably less than about 0.5%, and most preferably less than about 0.1%. Consequently, cocking and firing the crossbow 400 is highly repeatable. To the extent that manufacturing variability creates inaccuracy in the crossbow 400, any such inaccuracy are likewise highly repeatable, which can be compensated for with appropriate windage and elevation adjustments in the scope 414 (See
By contrast, conventional cocking ropes, cocking sleds and hand-cocking techniques lack the repeatability of the present string carrier 480, resulting in reduced accuracy. Windage and elevation adjustments cannot adequately compensate for random variability introduced by prior art cocking mechanism.
A cocking mechanism 484 (see e.g.,
In the drawn configuration 405 the distance 407 between the cam axles may be in the range of about between about 6 inches to about 8 inches, and more preferably about 4 inches to about 8 inches. In one embodiment, the distance 407 between the axles in the drawn configuration 405 is less than about 6 inches, and alternatively, less than about 4 inches.
When in the drawn configuration 405 illustrated in
The small included angle 403 that results from the narrow separation 407 does not provide sufficient space to accommodate conventional cocking mechanisms, such as cocking ropes and cocking sleds disclosed in U.S. Pat. Nos. 6,095,128 (Bednar); 6,874,491 (Bednar); 8,573,192 (Bednar et al.); 9,335,115 (Bednar et al.); and 2015/0013654 (Bednar et al.), which are hereby incorporated by reference. It will be appreciated that the cocking systems disclosed herein are applicable to any type of crossbow, including recurved crossbows that do not include cams or conventional compound crossbows with power cables that crossover.
Pivots 432A, 432B (“432”) attached to the riser 404 engage with the limbs 420 proximally from the mounting brackets 422. The pivots 432 provide a flexure point for the limbs 420 when the crossbow 400 is in the drawn configuration.
Cams 440A, 440B (“440”) are attached, to the limbs 420 by axle mounts 442A, 442B (“442”). The cams 440 preferably have a maximum diameter 441 less than the power stroke (see e.g.,
In the illustrated embodiment, the axle mounts 442 are attached to the limbs 420 offset a distance 446 from the proximal ends 444A, 444B (“444”) of the limbs 420. Due to their concave shape, greatest width 448 of the limbs 420 (in both the drawn configuration and the release configuration) preferably occurs at a location between the axle mounts 442 and the pivots 432, not at the proximal ends 444.
The offset 446 of the axle mounts 442 maximizes the speed of the limbs 420, minimizes limb vibration, and maximizes energy transfer to the bolts 416. In particular, the offset 446 is similar to hitting a baseball with a baseball bat at a location offset from the tip of the bat, commonly referred to as the “sweet spot”. The size of the offset 446 is determined empirically for each type of limb. In the illustrated embodiment, the offset 446 is about 1.5 to about 4 inches, and more preferably about 2 to about 3 inches.
Tunable arrow rest 490 is positioned just behind the pocket 426. A pair of supports 492 are secured near opposite sides of the bolt 416 by fasteners 494. The supports 492 preferably slide in the plane of the limbs 420. As best illustrated in
The distal end 700 includes stem 706 that extends into hollow handle 708. Pins 710 permit the stem 706 to rotate a few degrees around pin 712 in either direction within the hollow handle 708. As best illustrated in
The string carrier 480 includes fingers 500 on catch 502 that engage the draw string 501. The catch 502 is illustrated in a closed position 504. After firing the crossbow the catch 502 is retained in open position 505 (see
In the closed position 504 illustrated in
In one embodiment, a force necessary to overcome the friction at the interface 533 to release the catch 502 is preferably less than the biasing force applied to the sear 514 by the spring 511. This feature causes the sear 514 to return fully to the cocked position 524 in the event the trigger 558 is partially depressed, but then released before the catch 502 releases the draw string 501.
In another embodiment, a force necessary to overcome the friction at the interface 533 to release the catch 502 is preferably less than about 3.2%, and more preferably less than about 1.6% of the draw force to retain the draw string 501 to the drawn configuration. The draw force can optionally be measured as the force on the flexible tension member 585 when the string carrier 480 is in the drawn position (See
Turning back to
A dry fire lockout biasing force is applied by spring 540 to bias dry fire lockout 542 toward the catch 502. Distal end 544 of the dry fire lockout 542 engages the sear 514 in a lockout position 541 to prevent the sear 514 from releasing the catch 502. Even if the safety 522 is disengaged from the sear 514, the distal end 544 of the dry fire lockout 542 retains the sear 514 in the cocked position 524 to prevent the catch 502 from releasing the draw string 501.
As best illustrate in
To cock the crossbow 400 again the string carrier 480 is moved forward to location 483 (see
The cocking mechanism 484 includes a rotating member, such as the spool 560, with a flexible tension member, such as for example, a belt, a tape or webbing material 585, attached to pin 587 on the string carrier 480. As best illustrated in
A pair of pawls 572A, 572B (“572”) include teeth 574 (see
In operation, the user presses the release 576 to disengage the pawls 572 from the spool 560 and proceeds to rotate the cocking handle 454 to move the string carrier 480 in either direction 482 along the rail 402 to cock or de-cocking the crossbow 400. Alternatively, the crossbow 400 can be cocked without depressing the release 576. but the pawls 572 will make a clicking sound as they advance over the gear teeth 568.
Upper power cables 610A are attached to the power cable bracket 608 at upper attachment points 612A and to power cable attachments 462A on the cams 440 (see also
In the illustrated embodiment, the attachment points 612A, 612B for the respective power cables 610 are located on opposite sides of the center rail 402. Consequently, the power cables 610 do not cross over the center rail 402. As used herein, “without crossover” refers to a cabling system in which power cables do not pass through a vertical plane bisecting the center rail 402.
As best illustrated in
In the illustrated embodiment, the draw string journal 464 rotates between about 270 degrees and about 330 degrees, and more preferably from about 300 degrees to about 360 degrees, when the crossbow 400 is drawn from the, released configuration 600 to the drawn configuration 620. In another embodiment, the draw string journal 464 rotates more than 360 degrees (see
Spring 540A biases dry fire lockout 542A toward the catch 502. Distal end 544A of the dry fire lockout 542A engages the sear 514 in a lockout position 541 to prevent the sear 514 from releasing the catch 502. Even if the safety 522 is disengaged from the sear 514, the distal end 544A of the dry fire lockout 542A locks the sear 514 in the closed position 504 to prevent the catch 502 from releasing the draw string 501.
As illustrated in
In the illustrated embodiment, the portion 543A on the dry fire lockout 542A is positioned behind the draw string location 501A. As used herein, the phrase “behind the draw string” refers to a region between a draw string and a proximal end of a crossbow. Conventional flat or half-moon nocks do not extend far enough rearward to reach the portion 543A of the dry fire lockout 542A, reducing the chance that non-approved arrows can be launched by the crossbow 400.
Upper roller 652 is located near the entrance of the arrow capture recess 650. The upper roller 652 is configured to rotate in the direction of travel of the arrow 416 as it is launched. That is, the axis of rotation of the upper roller 652 is perpendicular to a longitudinal axis of the arrow 416. The upper roller 652 is displaced within the slot in a direction generally perpendicular to the arrow 416, while spring 654 biases the upper roller 652 in direction 656 against the arrow 416. As best illustrated in
In the illustrated embodiment, the clip-on nock 417 must be fully engaged with the draw string 510A near the rear of the arrow capture recess 650 to disengage the dry fire lock out 542A. In this configuration (see
In one embodiment, the lower angled surfaces 658 do not support the arrow 416 in the arrow capture recess 650 unless the clip-on neck 417 is used. In particular, the upper angled surfaces 660 prevent the nock 417 from rising upward when the crossbow 400 is fired, but the arrow 417 tends to slide downward off the lower angled surfaces 658 unless the clip-on nock 417 is fully engaged with the draw string 510A.
By contrast, prior art crossbows typically include a leaf spring or other biasing structure to retain the arrow against the rail. These devices tend to break and are subject to tampering, which can compromise accuracy.
In an alternate embodiment, the drive shaft 564 is three discrete pieces 565A, 565B, 565C connected by torque control mechanisms located in housings 567A, 567B. A torque control mechanism 722 generally as illustrated in
The string carrier 480 hits a mechanical stop when it is fully retracted, which corresponds to maximum draw string 501 tension. Tension on the draw string 501 is highly repeatable and uniform throughout the string system due to the operation of the string carrier 480. Further pressure on the cocking handle 720 causes the coupling 724 to slip within the head 729, preventing excessive torque on the cocking mechanism 484 and tension on the flexible tension member 585.
As best seen in
As best seen in
A variety of conventional cocking ropes 810 can releasably engage with the pulleys 804. The hooks found on conventional cocking ropes are not required. As best illustrated in
It will be appreciated that a variety of different cocking rope configurations can be used with the string carrier 480, such as disclosed in U.S. Pat. Nos. 6,095,128 (Bednar): 6,874,491 (Bednar); 8,573,192 (Bednar et al.); 9,335,115 (Bednar et al.); and 2015/0013654 (Bednar et al.), which are hereby incorporated by reference.
In one embodiment, the cocking ropes 810 retract into handles 812 for convenient storage. For example, protrusions 826 on handles 812 can optionally contain a spring-loaded spool that automatically retracts the cocking ropes 810 when not in use, such as disclosed in U.S. Pat. No. 8,573,192 (Bednar et al.). In another embodiment, a retraction mechanism for storing the cocking ropes when not in use are attached to the stock 408 at the location of the anchors 816 such as disclosed in U.S. Pat. No. 6,874,491 (Bednar). In another embodiment, a cocking rope retraction system with a spool and crank handle can be attached to the stock 408, such as illustrated in U.S. Pat. No. 7,174,884 (the '884 Kempf Patent”).
In operation, when the draw string 501 is in the released configuration 600 the user slides the string carrier 480 forward along the rail into engagement with the draw string 501. The catch 502 (see e.g.,
In the embodiment illustrated in
In order to de-cock the crossbow 400, the user pulls the handles 812 to retract the string carrier 480 toward the stock 408 a sufficient amount to disengage the hook 818 from the pin 819. In one embodiment, the user rotates the release lever 820 in direction 821 about 90 degrees. The release lever 820 biases the hook 818 in direction 822, but the force 824 prevents the hook 818 from moving in direction 822. The user then pulls the handles 812 toward the stock 408 to remove the force 824 from the hook 818. Once the pin 819 clears the hook 818 the biasing force applied by the release lever 820 moves the hook 818 in direction 822. The user can now slowly move the string, carrier 480 toward the released configuration 600.
As illustrated in
In particular, when in the drawn configuration tension forces on the draw string 501 on opposite sides of the string carrier 480 are substantially the same, within less than about 1.0%, and more preferably less than about 0.5%, and most preferably less than about 0.1%. Consequently, cocking and firing the crossbow 400 is highly repeatable.
To the extent that manufacturing variability creates inaccuracy in the crossbow 400, any such inaccuracy are likewise highly repeatable, which can be compensated for with appropriate windage and elevation adjustments in the scope 414 (See
The crossbow 900 includes a center rail 402 with a riser 404 mounted at the distal end 406 and a stock 408 located at the proximal end 410. The center rail 402 and riser 404 may be referred to herein as the frame 904. The riser 404 includes a pair of limbs 420A, 420B (“420”) extending rearward toward the proximal end 410.
Cams 440A, 440B are attached to the frame 904, rather than the limbs 420. In the illustrated embodiment, the cams 440 are attached to the center rail 402 by axle mounts 442A, 442B. The cams 440 rotate around axes 443A, 443B (“443”) on respective axle mounts 442A, 442B, but otherwise do not move relative to the frame 904. The locations of axes 443 are fixed relative to the center rail 402 and the riser 404, even as the limbs 420 and the draw string 501 move. Consequently, energy stored in the limbs 420 when the crossbow 900 is in the drawn configuration 405 is not diverted to accelerating the mass of the cams 440, resulting in greater energy transferred to the arrow 416. The stationary cams 440 and cam axles 442 also eliminates any inaccuracy introduced by moving the cams 440 with the limbs 420 when firing a conventional crossbow.
Draw string 501 is engaged with draw string journals 464 (see e.g.,
Power cables 610A, 610B are attached to the limbs 420A, 420B, respectively. Opposite ends of the power cables 610 are attached to the power cable attachments 462 on the cams 440. The cams 440 include power cable journals 460A, 460B that receive respective power cables 610A, 610B as the draw string 510 is moved from the released configuration 600 to the drawn configuration 405.
In the preferred embodiment, each limb 420 includes upper and lower power cables 610 that engaged with upper and lower power cable journals 460 on the cams 440 (see e.g.,
Draw string 501 is preferably retracted to the drawn configuration 405 shown in
The stationary axes 443 preferably have a fixed separation 902 of between about 3 inches to about 8 inches, and more preferably, about 4 inches. The drawn configuration 405 illustrated in
In the drawn configuration 405 of
The riser 404 extends along the center rail 402 to provide attachment locations for both the limbs 420 and the cams 440. The cams 440 are attached to the riser 404 closer to the distal end 406 and rotate around axes 443. In one embodiment, the axle mounts 442 are machined directly into the riser 404. Alternatively, the axial mounts 442 are discrete components attached to the riser 404.
Center portions 922 of the riser 404 have a width 924 greater than the draw string 501 when in the drawn configuration 405 as illustrated in
Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within this disclosure. The upper and lower limits of these smaller ranges which may independently be included in the smaller ranges is also encompassed within the disclosure, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either both of those included limits are also included in the disclosure.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the various methods and materials are now described. All patents and publications mentioned herein, including those cited in the Background of the application, are hereby incorporated by reference to disclose and described the, methods and/or materials in connection with which the publications are cited.
The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present disclosure is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed.
Other embodiments, are possible. Although the description above contains much specificity, these should not be construed as limiting the scope of the disclosure, but as merely providing illustrations of some of the presently preferred embodiments. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of this disclosure. It should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes disclosed. Thus, it is intended that the scope of at least some of the present disclosure should not be limited by the particular disclosed embodiments described above.
Thus the scope of this disclosure should be determined by the appended claims and their legal equivalents. Therefore, it will be appreciated that the scope of the present disclosure fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the present disclosure is accordingly to be limited by nothing other than, the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” All structural, chemical, and functional equivalents to the elements of the above-described preferred embodiment that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved by the present disclosure, for it to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims.
Claims
1. A crossbow comprising:
- a frame comprising a center rail;
- first and second flexible limbs attached to the frame;
- a first cam assembly mounted to the frame and rotatable around a first axis located a fixed distance from the center rail, the first cam assembly comprising a first draw string journal having a first plane of rotation perpendicular to the first axis, and a first power cable take-up journal comprising a path that is not co-planar with the first plane of rotation;
- a second cam assembly mounted to the frame and rotatable around a second axis located a fixed distance from the center rail, the second cam assembly comprising a second draw string journal having a second plane of rotation perpendicular to the second axis, and a second power cable take-up journal comprising a path that is not co-planar with the second plane of rotation;
- a draw string received in the draw string journals with the draw string adjacent a clown-range side when in a released configuration and secured to the first and second cam assemblies, wherein the draw string unwinds from the draw string journals as it translates from a released configuration to a drawn configuration, wherein a separation between the first axis and the second axis is fixed at about 3 inches to about 8 inches and the draw string in the drawn configuration comprises an included angle of less than about 25 degrees; and
- first and second power cables having first ends operatively coupled to the first and second cam assemblies and received in the first and second power cable take-up journals, and second ends operatively coupled to the first and second flexible limbs, respectively;
- wherein the first and second power cables wrap at least 270 degrees around the respective first and second power cable take-up journals as the drawstring is moved between the released configuration to the drawn configuration, and the first and second cables unwrap at least 270 degrees from the respective first and second power cable take-up journals as the drawstring is moved between the drawn configuration to the released configuration.
2. The crossbow of claim 1 wherein the first and second cam assemblies are mounted to a riser attached to the center rail.
3. The crossbow of claim 1 wherein a draw weight on the draw string increases continuously as the crossbow is drawn from the released configuration to the drawn configuration.
4. The crossbow of claim 1 wherein the first and second power cable take-up journals displace the first and second power cables along the first and second axes relative to the first and second planes of rotation, respectively, as the drawstring is moved between the released configuration to the drawn configuration.
5. The crossbow of claim 1 wherein the draw string translates from the release configuration to the drawn configuration comprising a power stroke of about 10 inches to about 15 inches.
6. The crossbow of claim 1 wherein the first and second cam assemblies rotate between about 300 degrees to about 360 degrees when the crossbow is drawn from the released configuration to the drawn configuration.
7. The crossbow of claim 1 wherein the first and second power cable take-up journals comprise helical power cable take-up journals.
8. The crossbow of, claim 1 wherein the first and second power cable take-up journals comprise a width at least twice a width of the first and second of power cables.
9. The crossbow of claim 1 wherein the first and second power cable take-up journals each comprise first and second upper and lower power cable take-up journals on opposite sides of the first and second draw string journals, respectively, and the first and second power cables comprise a pair of first and a pair of second power cables.
10. The crossbow of claim 1 wherein the draw string in the drawn configuration comprises an included angle of less than about 15 degrees.
11. The crossbow of claim 1 wherein limb tips of the first and second flexible limbs overlap the first and second cam assemblies when the crossbow is in the drawn configuration.
12. The crossbow of claim 1 comprising:
- a string carrier captured by the center rail that slides forward to engage with the draw string in the released configuration and slides rearward to a retracted position that locates the draw string in the drawn configuration, the string carrier comprising a catch movable between a closed position that engages the draw string and an open position that releases the draw string, a sear moveable between a cocked position coupled with the catch to retain the catch in the closed position and a de-cocked position that release the catch to the open position, and a safety moveable between a free position and a safe position that prevents the catch from moving to the open position; and
- a trigger mounted to the center rail that selectively moves the catch from the closed position to the open position that releases the draw string from the string carrier while the string carrier is in the retracted position.
13. The crossbow of claim 12 comprising:
- a cocking mechanisms with a rotating member coupled to a flexible tension member attached to the string carrier; and
- a cocking handle configured to rotate the rotating member to move the string carrier to the retracted position.
14. The crossbow of claim 13 comprising a torque control mechanism with an integral clutch that limits output torque applied to the rotating member by the cocking handle such that rotating the cocking handle after the string carrier is in the retracted position causes the cocking handle to slip to limit torque applied to the cocking mechanism.
15. The crossbow of claim 12 comprising:
- at least one cocking rope configured to releasably engage with the string carrier to retract the string carrier and the draw string to the drawn configuration; and
- a retaining mechanism that releasably retains the string carrier in the retracted position and the draw string in the drawn configuration.
16. A crossbow comprising:
- a frame comprising a center rail;
- first and second flexible limbs attached to the frame;
- a first cam assembly mounted to the frame and rotatable around a first axis located a fixed distance from the center rail, the first cam assembly comprising a first draw string journal having a first plane of rotation perpendicular to the first axis, and a first helical power cable take-up journal comprising a path that is not co-planar with the first plane of rotation;
- a second cam assembly mounted to the frame and rotatable around a second axis located a fixed distance from the center rail, the second cam assembly comprising a second draw string journal having a second plane of rotation perpendicular to the second axis, and a second helical power cable take-up journal comprising a path that is not co-planar with the second plane of rotation;
- a draw string received in the draw string journals in a reverse draw configuration with the draw string adjacent a down-range side when in a released configuration and secured to the first and second cam assemblies, wherein the draw string unwinds from the draw string journals as it translates from a released configuration to a drawn configuration, wherein a separation between the first axis and the second axis is about 3 inches to about 8 inches and the draw string in the drawn configuration comprises an included angle of less than about 25 degrees; and
- first and second power cables having first ends received in the first and second helical power cable take-up journals, and second ends operatively coupled to the first and second flexible limbs, respectively;
- wherein the first and second helical power cable take-up journals displace the first and second power cables along the first and second axes relative to the first and second planes of rotation, respectively, and the first and second power cables wrap at least 270 degrees around the respective first and second helical power cable take-up journals as the drawstring is moved between the released configuration to the drawn configuration, and the first and second power cables unwrap at least 270 degrees from the respective first and second helical power cable take-up journals as the drawstring is moved between the drawn configuration to the released configuration.
17. A method of operating a crossbow comprising the steps of:
- locating a draw string in first and second draw string journals on first and second cam assemblies, the first and second cam assemblies having first and second planes of rotation that are perpendicular to first and second axes of rotation located a fixed distance from the frame, respectively, and first and second helical power cable take-up journal comprising paths that are not co-planar with the first and second planes of rotation;
- translating the draw string from a released configuration to a drawn configuration so the draw string unwinds from the draw string journals as the first and second cam assemblies rotate around the first and second axes, wherein a separation between the first axis and the second axis is about 3 inches to about 8 inches and the draw string in the drawn configuration comprises an included angle of less than about 15 degrees;
- wrapping the first and second power cables more than 270 degrees onto the first and second helical power cable take-up journals as the draw string translates from the released configuration to the drawn configuration, the first and second power cables having first ends operatively coupled to the first and second cam assemblies and second ends operatively coupled to the first and second flexible limbs, respectively;
- displacing the first and second power cables along the first and second axes relative the first and second planes of rotation of the first and second draw string journals as the bow string is translated from the released configuration to the drawn configuration; and
- unwrapping the first and second power cables more than 270 degrees from first and second helical power cable take-up journals as the draw string translates from the drawn configuration to the released configuration.
18. The method of claim 17 comprising the steps of:
- sliding a string carrier captured by the center rail forward and into engage with the draw string in the released configuration;
- moving a catch on the string carrier to a closed position that engaged the draw string;
- sliding the string carrier to a retracted position that locates the draw string in the drawn configuration; and
- engaging a trigger mounted to the center rail with the catch when the string carrier is in the retracted position to move the catch from the closed position to an open position that releases the draw string from the string carrier.
19. The method of claim 18 comprising rotating a cocking handle engaged with a cocking mechanism to retract the draw string to the drawn configuration.
20. The method of claim 19 comprising activating a torque control mechanism in the cocking handle to limit torque applied to the cocking mechanism.
Type: Application
Filed: Dec 31, 2018
Publication Date: May 9, 2019
Inventor: Craig Thomas Yehle (Winona, MN)
Application Number: 16/237,062