The present disclosure relates generally to archery bows and more particularly pertains to an improved limb pocket rocker for use in limb pockets of archery bows and a method for manufacturing the same.
Compound archery bows generally including a bow frame having a handle or riser and two bow limbs (or four “quad” bow limbs), plus a cable system on the frame mounted to at least two rotational elements such as wheels. Archery bow limbs perform the function of storing energy when the archer draws the bowstring. When the bowstring is drawn, the pre-stressed bow limbs, which are typically made of resilient material, are further flexed to store additional energy. When the bowstring is released, the stored energy propels the arrow. In conventional compound bows, each limb is typically formed of a single element with a rectangular cross section, where one end is attached to the bow handle and the other end has a limb tip slot formed therein, in which a rotational member such as a wheel, cam or pulley is mounted. In “quad” compound archery bows, two pairs of “quad” bow limbs are used, each having one end attached to the bow handle or riser and the other end coupled with the rotational member.
In certain archery bows, the ends or butt sections of the limbs are received and secured in limb pockets attached to ends of the riser. It is important for the limbs to be properly aligned with the riser and securely mounted to the riser to prevent movement of the limb ends. In many limb pocket arrangements a rocker or spacer is positioned within the limb pocket and slightly spaced away from the end as a fulcrum between the bow and the limb. The rocker contacts portions of the archery bow limbs and moves or rock with the bow limbs as they are flexed during use of the archery bow.
Limb end thickness can vary due to multiple factors such as limb weight, paint buildup, film thickness, etc. This can vary between different bow models for a manufacturer and sometimes between different limb batches made for the same model. Consequently, it can be a challenge to make a standardized limb rocker which fits different limb end thicknesses.
There is a need for improved archery bow limb pocket rockers.
In one embodiment, an archery bow comprises a riser portion with an upper end and a lower end, and at least one bow limb portion having a butt section. The archery bow includes at least one limb pocket with a rocker positioned between the riser portion and the bow limb portion such that the bow limb contacts the rocker. The rocker is designed to rest or loosely fit in a groove in the limb pocket, and is arranged between the groove and fulcrum points on the limb. The rocker has a length with an upper face which defines one or two limb channels; with each channel engaging the butt end of a limb. Rocker sidewalls flex inward as compression is applied to the rocker during assembly so that said inward lateral faces apply a clamping force to the sidewalls of said limb. Rocker sidewall portions extend upward adjacent the sidewalls of each limb. In certain embodiments, the rocker is configured to flex to apply a clamping force to the limbs as the limb pocket is assembled.
In certain embodiments, the rocker defines a slot extending downward from each limb track into the lower half of the rocker. The slots are adjacent the inward faces of each channel. The slots define hinge portions which allow the channel and end portions of the rocker to slightly flex relative to a central portion in order to apply clamping force to the limbs.
In some embodiments, the lower face of the rocker is formed with a rounded surface to match a rounded groove in the limb pocket. In an uninstalled/non-compressed state, the longitudinal rocker length may define a concave arcuate curve or end portions may be bent slightly downward relative to the center portion.
When the limb pocket and limbs are assembled, the limbs are placed in the channels and press the rocker into the limb pocket groove. The pressure presses the rocker central portion into the groove. Correspondingly, the rocker lateral end portions flex or rotate slightly upward and inward relative to the central portion. This compresses the slots and also flattens the lower surface of the rocker into the limb groove. Correspondingly, the rocker limb tracks are compressed against the limbs, applying a clamping action between the rocker ends and the central portion. The clamping action fits the rocker to the limbs and assists in holding the limbs in place.
Other objects and attendant advantages of this disclosure will be readily appreciated as the same become more clearly understood by references to the following detailed description when considered in connection with the accompanying drawings in which like reference numerals designate like parts throughout the figures thereof.
For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended, such alterations, modifications, and further applications of the principles of the disclosure being contemplated as would normally occur to one skilled in the art to which the disclosure relates.
The present disclosure is directed to limb pocket fulcrums or rockers for use in limb pockets of archery bows. A typical compound archery bow comprises a riser portion with an upper end and a lower end, with bow limbs attached to and extending from the riser, each limb having a butt, tip and hinge section. An archery bow often includes a pair of limb pockets coupled to the upper and lower ends of the riser portion and configured to receive the butt sections of the limbs. Additionally, the archery bow may comprise a pair of rockers positioned within the limb pockets, such that portions of the limbs contact the rockers. The rockers of the present disclosure include aspects that impart a clamping action that fits the rocker to the limbs during assembly and assists in holding the limbs in place.
Bowstring 34 includes upper end 28 and lower end 30 which are fed-out from pulleys 16 and 18 when the bow is drawn. Bowstring 34 may be mounted around pulleys 16 and 18 as is known in the art. As illustrated, Y-yoke anchor cables 32 and 33 each preferably extend from one pulley to the axle of the other pulley.
When the bowstring 34 is drawn, it causes eccentric pulleys 16 and 18 at each end of the bow to rotate, feeding out cable and bending limb portions 12 and 14 inward, causing additional energy to be stored therein. When the bowstring 34 is released with an arrow engaged to the bowstring, the limb portions 12 and 14 return to their rest position, causing the eccentric pulleys 16 and 18 to rotate in the opposite direction, to take up the bowstring 34 and launch the arrow with an amount of energy proportional to the energy initially stored in the bow limbs. Bow 10 is described for illustration and context and is not intended to be limiting. The present disclosure can be used with dual-cam compound bows, or can be used with single-cam bows as illustrated in
Bow 100 may include limb pockets 102 attached to the upper and lower ends of riser 101. Pockets 102 are configured to receive butt sections 112a-115a of quad limbs 112-115 to secure the limbs to the riser. The housing of pockets 102 may be conventional. Positioned within pockets 102 are fulcrums or rockers 210, described in greater detail below. Rockers 210 are configured to contact portions of the bow limbs, and may be configured to at least slightly rotate or rock within the limb pocket corresponding to flexion of the bow limbs during use of the archery bow. In the illustrated embodiment, rockers 210 are used in conjunction with a “quad” archery bow having four total quad bow limbs, with each rocker contacting two quad bow limbs. Accordingly, rocker 210 is also configured to separate the two corresponding quad bow limbs. In other embodiments, each rocker could be used with an archery bow having single bow limbs at each end, such as illustrated in
As illustrated in
The specific geometry of the illustrated rocker 210 is discussed generally with reference to the various views illustrated in
Part-rounded portion 224 is configured to sit within seat 160 of limb pocket 210, such that concave surface 162 mates with convex surface 224. Bottom surface 224 may have a different radius (or radii) of curvature than as illustrated, as would occur to one of ordinary skill in the art. In certain embodiments, part-rounded portion 224 may be half-cylindrical spanning approximately 180 degrees. In certain other embodiments, portion 224 may be a greater or less segment of a cylinder (or other rounded shape) as would occur to one skilled in the art. In alternative embodiments, the bottom portion of the rocker may be square or rectangular in shape.
Rocker 201 includes a height Hs along axis H. In a quad limb arrangement central portion 220 has a height Hs forming limb separator 222. Single limb embodiments do not include a limb separator portion. In the illustrated embodiment, central portion 220 defines opposing outward facing lateral faces 226. Lateral faces 226 may be substantially vertical when assembled or optionally the upper portions of faces 226 may taper slightly outward toward end portions 230.
End portions 230 each include an endwall 234 with a height Hs along height axis H. End portions 230 define upward facing surfaces 232 between central portion 220 and endwall 234. Upward facings surfaces 232 may be substantially horizontal when assembled, yet may be slightly skewed from horizontal prior to assembly. End walls 234 each define an inward lateral face 236. Inward lateral faces 236 may be substantially vertical when assembled, or optionally the upper portions of inward lateral faces 236 may taper slightly toward central portion 220. In an unassembled state, inward lateral faces 236 may be slighted skewed from vertical.
In certain embodiments, rocker 210 includes a pair of hinge slots 240. Hinge slots 240 are illustrated with an axis along width axis W and are arranged adjacent to and parallel to outward lateral faces 226. Hinge slots extend downward into rocker 220 below upward facing surfaces 232, partially separating central portion 220 from each end portion 230. The depth of hinge slots 240 is a proportion of yet less than the height of the upward facing surfaces 232, so that the end portions 230 remain connected to central portion 220. In certain embodiments, the depth of hinge slots is forty percent or greater of the height of upward facing surfaces 232. In alternate embodiments, hinge slots 240 may be arranged adjacent to or inward from end walls 234 or hinge slots 240 may be arranged at selected points along the length of upward facing surfaces 232. Slots 240 each define a hinge section, allowing the portions on either side of the hinge section to slightly rotate or flex relative to each other. In alternate embodiment, hinge slots are optional and a hinge affect could be achieved via compression of the rocker material.
In combination, outward lateral faces 226, upward facing surfaces 232 and inward lateral faces 236 define limb tracks 238. As illustrated, a pair of parallel limb tracks 238 are shown corresponding to a quad limb arrangement. In a single limb embodiment, a pair of inward lateral faces 236 and a single upward facing surface 232 define a single limb track, with the upward facing surface 232 extending at a consistent height between lateral faces 236.
As the limbs are vertically pressed and clamped into place in pocket 102, rocker 210 is clamped between the limbs and the limb pocket. This presses rocker 210 into limb pocket groove 160. This pressure causes end portions 230 to contact groove 160 first. As the rocker continues to be compressed into groove 160, central portion 220 lowers into contact with groove 160 and end portions 230 radially flex or rotate slightly upward and inward relative to central portion 220, along the axes of hinge slots 240. In certain embodiments this causes the inward lateral face to rotate relative to the outward lateral face thus changing the angle between them. The clamping force in combination with the flex and rotation flattens lower surface 224 of the rocker into limb groove 160 along the length of rocker 210, flattening the profile of lower surface 224 along its length into a linear or substantially straight line along axis L.
As end portions 230 radially flex and rotate upward, outward lateral faces 226 are laterally compressed toward inward lateral faces 236. In certain embodiments, outward lateral faces 226 slightly flex and rotate toward inward lateral faces 236. This causes outward lateral faces 226 and inward lateral faces 236 to bear upon and conform to the size and contour of the limb sidewalls, applying a clamping pressure to the sidewalls of limbs 112, 113. Geometrically, the lateral clamping force applied on the limb sidewalls is perpendicular to the vertical limb clamping force applied as the limb is secured to the riser and in the limb pocket. The magnitude of the lateral clamping force applied is also increased and greater than any incidental contact lateral force that may initially exist, for example if the limb is initially friction fitted into a rocker track. The limb sidewall clamping action ensures a snug nested fit between the rocker and the limbs and assists in holding the limbs in place. The clamping action is able to accommodate variations in limb size and thickness.
Rockers 210 are preferably at least slightly flexible and/or compressible to accommodate the varying radius of the bow limbs as they flex during use of the archery bow. Additionally, rockers 210 may be composed of one or more of a variety of appropriate materials, for examples including a plastic or rubber. In certain embodiments, rockers 210 may be composed of a nylon material. It is contemplated that rockers 210 may be formed using an injection molding process involving a mold assembly shaped and configured to form the rockers. In certain embodiments, the material is heated in the mold assembly and then cured by being placed in an oven and heated at a desired temperature. If necessary, final machining may be done to complete the forming process. In certain other embodiments, it is contemplated that rockers 210 may be formed by other appropriate manners. In the illustrated embodiment, the corners within the rockers include radiused corner profiles. These are provided to avoid having to machine grind or cut stress-inducing sharp corners. In such embodiments, the radius corner profiles may be formed by molding in the radius via a mold assembly. There could be greater or fewer radius corner profiles than as illustrated. In other embodiments, radius corner profiles are absent from the rockers.
While the disclosure has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected.
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