Mechanical guns and projectors – Spring – Bow
Reexamination Certificate
2003-05-07
2004-03-02
Ricci, John A. (Department: 3712)
Mechanical guns and projectors
Spring
Bow
C124S023100
Reexamination Certificate
active
06698413
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a compression spring powered, archery bow which is adjustable for draw weight, draw length and draw weight let-off at full draw length in a rigid frame that is integrated to form one continuous loop in the shape of a contemporary archery bow.
BACKGROUND OF THE INVENTION
Many attempts have been made in the development of the archery bow to make it more adjustable in order to provide a single design which can be used universally by archers of all ages. The present designs generally all lack the ability to perform this task while being compact, easily and independently adjusted, simplistic, cost effective and aesthetically pleasing. Prior art in this filed shows designs that are overly complex or designs that do not fill the above stated criteria.
U.S. Pat. No. 4,903,677 issued to Colley et al. on Feb. 27, 1990 describes an archery bow in which at least one flat wound coil spring is mounted on a rigid limb frame and is connected through an eccentric wheel or cam, a drive sprocket and a drive wheel or storage spool to a bowstring so that the action of drawing back the bowstring causes the flat wound coil spring to be wound up storing energy. A let-off arrangement for reducing the force string movement of the string between an at-rest position and a fully drawn position is a function of the flat wound coil spring, the eccentric wheel or cam and the relative dimensions of the drive sprocket and storage spool. The size of the storage spool determines the amount of draw length by functioning to store more or less bowstring in the at-rest position of the bow. Draw weight adjustment is limited to altering the pre-load on the flat wound coil spring at the time that the spring is installed on the bow. In this design, let-off action is interdependent upon larger and smaller diameter drive and driven wheels, their mounting shafts, and the eccentric wheel or cam. In addition, draw weight and draw length adjustment are not easily accomplished without an involved interchanging of the storage spool and flat wound coil spring, respectively.
U.S. Pat. No. 5,503,135 issued to Bunk on Apr. 2, 1996 discloses an archery apparatus which includes a main sheave rotatably mounted on the lower limb of a rigid main frame and engaged with a bowstring extending between guide sheaves on opposing ends of the frame. A pair of tensioning mechanisms are located on opposite sides of the lower limb of the frame for selectively applying torque to the main sheave responsive to drawing of the bowstring. Each tensioning mechanism includes a coil spring, a cable attached at one end to the spring and at another end to a connection member on the sheave, and a cam sheave engaged by the cable and rotatably mounted on the frame in spaced relationship from the main sheave. Any desired residual level of draw weight let-off is provided as the periphery of the cam sheaves come into alignment with the connection members of the tensioning cables and the rotational axis of the main sheave. A pair of stop members is removably attached to the main sheave so as to abut the lower limb of the frame at the point of maximum desired draw length. The design of this archery bow does not allow a full range of onboard adjustability of draw weight and the tensioning springs are attached to the lower limb using various closely spaced holes which only allows for predetermined changes in spring pressure. In addition, constant elongation of the tensioning springs will result in eventual fatigue and declining torque capability. The Bunk design also does not allow for a more complete adjustability of draw weight let-off since the let-off system is integrated or tied into the tensioning springs through a set of cables and cams which again only permits predetermined changes.
Accordingly, it is desirable to offer a differently styled spring powered, rigid limb bow which overcomes the shortcomings of the prior art, and provides a contemporary, more simplistic design having independently and more fully and easily adjustable draw weight, draw length and let-off features which enable an arrow to be accurately shot with a high level of substantially vibrationless, high energy.
SUMMARY OF THE INVENTION
It is a general object of the present invention to provide a high efficiency archery bow which is universal in usage.
It is one object of the present invention to provide a compact, rugged and easily adjustable rigid limb bow.
It is also an object of the present invention to provide a spring powered, rigid limb bow having independently adjustable draw weight, draw length and draw weight let-off adjustments.
In one aspect of the invention, an archery bow includes a rigid frame having an upper limb, an opposite lower limb and a handle therebetween. An upper wheel is rotatably mounted to a free end of the upper limb. A lower wheel is rotatably mounted to a free end of the lower limb, the lower wheel having a sprocket attached thereto. The sprocket has a diameter which is smaller than a diameter of the lower wheel. A bowstring has one end attached to the upper wheel and another end attached to the lower wheel. The bowstring is windable about respective peripheries of the upper wheel and the lower wheel and is moveable between an at-rest position and a drawn position. The lower limb has a cavity defined by wall structure threaded to receive a cooperably threaded, rotatable spring housing containing a compressible power coil spring having one end engaged against a bottom surface of the spring housing and an opposite end engaged by a holding member. A cable passes centrally through the power coil spring and has one end fastened to the holding member and an opposite end passing through the bottom surface of the spring housing and fixedly secured to the sprocket on the lower wheel. A cam is rotatably mounted to the lower limb between the lower wheel and the spring housing, the cam having a periphery engaged by the cable. With this structure, rotation of the spring housing relative to the lower limb will selectively change the compression rate of the power coil spring without the need for disassembly of the spring housing or requiring an adjustment tool to apply an adjustable torque transmitted through the cable to the lower wheel and thereby establish a variable draw weight required to move a bowstring to the drawn position.
The archery bow includes an elongated straight cross brace extending between the free ends of the upper limb and the lower limb. The opposite ends of the cross brace are connected at rotational axes of the upper wheel and the lower wheel. A synchronizing string has one end attached to the upper wheel, another end attached to the lower wheel and a midportion passing through a retainer fixed to the cross brace. A synchronizing string is windable about respective peripheries of the upper wheel and the lower wheel. The periphery of the upper wheel is formed with first and second grooved tracks and the periphery of the lower wheel is formed with first and second grooved tracks. The bowstring is wound on the first tracks of the upper wheel and the lower wheel, and the synchronizing string is wound on the second tracks of the upper wheel and the lower wheel. The lower wheel has a peripheral area formed with a plurality of threaded holes for facilitating adjustment of draw length of the bowstring. One of the holes receives a removably threaded, let-off pin engageable with a stop member located on the lower limb as the bowstring is drawn and the lower wheel is rotated against resistance of the power coil spring. The upper wheel and the lower wheel are located behind the handle of the frame. An independently adjustable, draw weight let-off mechanism is mounted on the lower limb and is engageable with the let-off pin as the bowstring is drawn and the lower wheel is rotated against resistance of the power coil spring. The adjustable let-off mechanism is independent of the power coil spring, the cable and the cam. The let-off mechanism includes a housing removably secured to the lower limb in a h
Andrus Sceales Starke & Sawall LLP
Ricci John A.
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