Patent Application
20150168093
The present disclosure is directed to a string guide system for a bow that permits greater rotation of the cams and pulleys, permitting a longer power stroke.
Bows 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 are 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 is drawn, such as illustrated in U.S. Pat. No. 7,836,871 (Kempf) and U.S. Pat. No. 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.
The present disclosure is directed to a string guide system for a bow that permits greater rotation of the string guides and a longer power stroke.
The present disclosure is also directed to an archery bow with a central portion having a down-range side and an up-range side. First and second flexible limbs attached to the central portion. A first string guide is mounted to the first bow limb and rotatable around a first axis. The first string guide includes a first draw string journal and a first power cable take-up journal, both oriented generally perpendicular to the first axis. The first power cable take-up journal includes a width measured along the first axis at least twice a width of a first power cable. A second string guide is mounted to the second bow limb and rotatable around a second axis. The second string guide includes a second draw string journal oriented generally perpendicular to the second axis. A draw string is received in the first and second draw string journals and secured to the archery bow in a reverse draw configuration with the draw string adjacent the down-range side in a release configuration. The draw string translates from the down-range side toward the up-range side and unwinds between the first and second string guides in a drawn configuration. A first power cable is received in the first power cable take-up journal and secured to the archery bow. The first power cable wraps onto the first power cable take-up journal and translates along the first power cable take-up journal away from the first draw string journal as the bow is drawn from the released configuration to the drawn configuration.
In one embodiment, a biasing force translates the first power cable away from the first draw string journal as the bow is drawn from the released configuration to the drawn configuration. In another embodiment, the first power cable take-up journal includes a helical journal that translates the first power cable away from the first draw string journal as the bow is drawn from the released configuration to the drawn configuration.
In another embodiment, the second string guides include a second draw string journal and a second power cable take-up journal, both oriented generally perpendicular to the second axis. The second power cable take-up journal includes a width measured along the second axis at least twice a width of a second power cable. A second power cable is received in the second power cable take-up journal and secured to the archery bow. The second power cable wraps onto the second power cable take-up journal and translates along the second power cable take-up journal away from the second draw string journal as the bow is drawn from the released configuration to the drawn configuration. In one embodiment, the power cables preferably do not cross over the center support.
The first and second string guides rotate more than 270 degrees, and preferably more than 360 degrees, when the bow is drawn from the release configuration to the drawing configuration.
The present disclosure is also directed to a method of operating a bow having a reverse draw configuration with a draw string located adjacent a down-range side of the string guide in a released configuration. The method includes displacing the draw string from the down-range side to a drawn configuration with the draw string located at an up-range side of the string guide. First and second string guides rotate around first and second axes, respectively, as the draw string is displaced from the released configuration to the drawn configuration. A first power cable take-up journal on the first string guide rotates around the first axis to take up a power cable as the bow is drawn from the released configuration to the drawn configuration. The first power cable take-up journal includes a width measured along the first axis at least twice a width of the first power cable. The first power cable is biased away from at least the draw string. The first power cable is translated along the first power cable take-up journal as the bow is drawn from the released configuration to the drawn configuration.
In one embodiment, the first power cable is translated away from the draw string by winding it on a helical journal.
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.
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.
In another embodiment, the surface 274 has a height 276 at least three times the diameter 278 of the power cable 102. Biasing force 280, such as from a cable guard located on the bow shifts the power cables 102 along the surface 274 away from top surface 282 of the string guide 270 when in the drawn configuration 284.
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 325. 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.
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.
