Patent Grant
10077963
See Application Data Sheet.
Not applicable.
Not applicable.
Not applicable.
Not applicable.
This invention relates to elements of arrow throwing devices, in particular to limbs used in bows and crossbows.
A variety of bow and crossbow designs are known in the art, with limbs being the main element thereof. The purpose of the limbs is to provide a high initial speed of an arrow. This is achieved due to making the limbs of a resilient material so when a bowstring is drawn, the limbs are flexed, and when the bowstring is released the limbs are straightened up, taking the initial shape. The more the flexing (straightening) amplitude and the limb's straightening speed are, the higher the arrow's initial speed is.
In order to increase the limb's straightening speed, the limbs are made of low-resilient materials. However, it needs applying higher forces for drawing the bowstring, which requires physical strength and, additionally, creates higher loads at the points where the limbs are attached to the handle of the bow or the body of the crossbow.
In order to increase a flexing (straightening) amplitude of the limbs, the limbs are usually made large. However, this makes an arrow throwing device bulky and heavy. For the purpose of eliminating this disadvantage two or more limbs may be applied. For example, as shown in FIG. 2 of U.S. Pat. No. 4,722,317, the flexible limbs 82, 88 are attached to the handle 80. Such designs are disadvantageous in that each limb is to be attached to a very long handle of a bow, which increases the device weight and affects operation reliability thereof.
In FIG. 3 of the same U.S. Pat. No. 4,722,317 is shown another embodiment, wherein the flexible resilient limb 200 is attached with the medium portion thereof to the handle 80, and both terminal ends of the limb 200 remain free and are used for mounting the bowstring and cable securing devices, namely pulleys 92, 94, 96, 98. Fixation of the limb's medium portion results in a higher load applied to the limb portions that move when the bowstring is drawn.
It is to be noted that a limb is a resilient element intended for accumulating energy for shooting. On one end thereof, the limb is attached to a non-resilient, stationary portion of an arrow throwing device (e.g., to a handle of a bow or a body of a crossbow). A bowstring and cables, if used, are secured to the other end of the limb via bowstring securing means and cable securing means, respectively. In particular, with reference to U.S. Pat. No. 4,722,317, limbs are understood as the elements designated by reference numbers 24, 26, 82, 84, 88, 90, 200, 202. The elements designated by reference numbers 32, 34 in FIG. 1 are «stationary arms», not the limbs.
U.S. Pat. No. 6,029,644 discloses the use of bow flexible limbs one end of each of which is fixed with the possibility of limited motion. The intermediate section of each limb is made flexible and is also fixed with the possibility of limited motion. This design enables to redistribute loads exerted on the limb intermediate section when the bowstring is drawn but, essentially, reduces the limb effective length since spatial motions of the limb intermediate section is limited and consequently, the limb lower section (reference number 25), which is connected at one of the ends thereof, cannot be fully involved into energy accumulation when the bowstring is drawn and the accumulated energy is being transferred to an arrow at shooting.
A greater length of a limb and compactness of an arrow throwing device may be achieved by making limbs of complex shape. For example, US Patent Application US 2015/0136106 provides for making S-shaped limbs. Since load exerted on the limbs of S-shape is irregular along the limb, the limbs are made so as to have a variable width, namely, the maximum width proximate to a handle of a bow and the minimum width proximate to free ends which a bowstring is secured to. However, when pulleys or the like for bowstring and cables are arranged at the free ends of the limbs, it is impossible to ensure narrowing of the limb's width proximate to the free ends, as otherwise the free ends may get broken. For this reason the S-shape of the limbs disclosed in US 2015/0136106 features more flat curvature and is in fact close to the C-shape. Thus, making the limbs S-shaped can hardly be applied in various arrow throwing devices. Stresses arising in the most bent portions of such the limb may significantly reduce lifetime of the arrow throwing device. Furthermore, high accuracy is required for making the S-shaped limbs, otherwise they may bend differently; therefore, using of the clamping means 952 for different adjustments of the limb 150A and the limb 150B are suggested by US 2015/0136106.
The objective of the invention is to provide limbs for an arrow throwing device, the limbs having such a shape and construction that ensures compactness thereof, increased lifetime, and high arrow speed simultaneously.
The technical effect of the invention is to ensure increased initial speed of an arrow while maintaining compact dimensions of the limbs and of an arrow throwing device comprising said limbs.
The above objective and technical effect are achieved in a limb for an arrow throwing device being the first object of the invention. The limb for an arrow throwing device comprises three portions: an upper portion, a lower portion and an intermediate portion, the intermediate portion being located between the upper portion and the lower portion. The upper portion and the lower portion are made resilient, and the intermediate portion is made non-resilient.
Resilience of a limb or a limb portion should be understood as capability of changing the shape, in particular, of bending when the limb or the limb portion is exposed to a load typical for loads arising in the limb or the limp portion during drawing a bowstring of an arrow throwing device.
The upper portion is connected with one end thereof to the intermediate portion. The opposite end of the upper portion is used for attaching a bowstring and cables, if used, directly thereto or via a device for securing a bowstring and/or cables installed on said opposite end of the upper portion.
The lower portion is connected at one end thereof to the intermediate portion, and the opposite end of the lower portion is secured on a frame of an arrow throwing device, i.e. on a handle of a bow or a body of a crossbow.
The intermediate portion is made non-resilient, as opposed to that disclosed in US 2015/0136106. The intermediate portion of the present invention serves as a connecting member between the upper portion and the lower portion and, at the same time, as a strengthening member of the whole limb. It enables to easily make limbs with most optimal distribution of resilience properties along the limb for the purpose of ensuring the maximum initial speed of an arrow. Furthermore, the intermediate portion enables to increase reliability and durability of operation the whole limb, when said portions of the limb are exposed to various loads each, the intermediate portion being exposed to the maximum load.
When the bowstring is being drawn, the limb according to the invention accumulates energy practically along the whole length thereof, as opposed to the limb of U.S. Pat. No. 6,029,644. This advantage over U.S. Pat. No. 6,029,644 is achieved due to that the claimed limb provides for only one region for attaching the limb to the frame of an arrow throwing device, said region being one of the ends of the lower portion. The intermediate portion, though made non-resilient under the conditions of typical loads applied, can freely move spatially when the bowstring is being drawn and released. Thus, the maximum motion amplitudes of the upper portion and the lower portion, which are connected by the intermediate portion, are used to accumulate and release energy.
Preferably, a size of the intermediate portion is significantly less than sizes of the upper portion and the lower portion. However, the size of the intermediate portion should be such that the intermediate portion is capable of performing functions of connecting the upper portion and the lower portion and being the strengthening element taking a load.
The upper portion, the intermediate portion and the lower portion may be made as a single member. In such a case it is advantageous if the intermediate portion has a cross-section area greater than cross-sections of the upper portion and the lower portion.
Alternatively, the upper portion, the intermediate portion and the lower portion may be made as separate members jointly connected. In this case it is easier to provide each portion of the limb with resilience, shape and other characteristics required for ensuring the maximum initial speed of an arrow.
In particular, at least two portions selected from the upper portion, the intermediate portion and the lower portion may be made of different materials. In particular, the upper portion and the lower portion may have different resilience; the intermediate portion may be made of a lighter or heavier material than that of the upper portion and lower portion; etc.
Furthermore, the upper portion, the intermediate portion and the lower portion may be connected therebetween with the possibility of disconnection thereof. This ensures compactness of both the limbs and the arrow throwing device when disassembled as well as enables to easily replace the portions of the limbs, if necessary.
The limb may have various shapes. For example, the upper portion and the lower portion may be arranged at an angle to each other, and the intermediate portion may be arranged at the vertex of said angle. According to an alternative embodiment, the upper portion and the lower portion may be arranged essentially along one line. The shape of the limb determines general dimensions and, consequently, weight of the limb, as well as the initial speed of an arrow.
Another object of the invention is a bow with limbs according to the above-described limbs. In particular, the bow comprises two limbs, where each limb features a first limb end and a second limb end; means for securing a bowstring installed at said first limb ends; a handle on which said two limbs are installed with second ends thereof; and a bowstring. Each limb comprises an upper portion, a lower portion and an intermediate portion. The intermediate portion is arranged between the upper portion and the lower portion. The upper portion and the lower portion are resilient, and the intermediate portion is non-resilient.
Yet another object of this invention is a crossbow, wherein the above-described limbs are used. In particular, the crossbow comprises two limbs, where each limb features a first limb end and a second limb end; means for securing a bowstring installed at said first limb ends; a body on which said two limbs are installed with second ends thereof; and a bowstring. Each limb comprises an upper portion, a lower portion and an intermediate portion. The intermediate portion is arranged between the upper portion and the lower portion. The upper portion and the lower portion are resilient, and the intermediate portion is non-resilient.
The bow and the crossbow may include any of the above-described embodiments of the limbs. It is obvious that in such a case the advantages of the above-described embodiments of the limbs relate to such the bow and the crossbow as well.
A limb 1 according to the invention comprises an upper portion 2, an intermediate portion 3 and a lower portion 4. At an end 5 of the lower portion 4 connecting means 7 for connecting to an arrow throwing device—a bow 8.1 or a crossbow 8.2—can be attached. A bowstring 10 is secured directly to a free end 6 of the upper portion 2 (
The upper portion 2 and the lower portion 4 of the limb 1 are made resilient, so, when the bowstring 10 is being drawn, said portions 2, 4 are bended, i.e. change their shape, and when the bowstring 10 is released, said portions 2, 4 return to their initial positions, i.e. take the initial shape. The intermediate portion 3 is not deformed, i.e. does not change its shape when using the limb, and in this sense the intermediate portion 3 is non-resilient.
The invariable shape, lack of deformation in the intermediate portion 3 means that the intermediate portion 3 is not involved in energy accumulation when the bowstring 10 is being drawn and in subsequent transfer of the accumulated energy to an arrow when the bowstring 10 is released. Energy is accumulated and transferred only due to bending of the upper portion 2 and the lower portion 4 of the limb 1, the limb 1 being attached to the arrow throwing device only via the end 5 of the lower portion 4, and the bowstring 10 is secured to the opposite end of the limb 1, namely to the free end 6 of the upper portion 2, either directly or via the securing means 11. When drawing the bowstring 10 the bend occurred practically along the whole length of the limb 1, except for the region where the intermediate portion 2 is arranged, enables to make draw of the bowstring 10 more smooth and simple with large amplitude, which ensures a high initial speed of the arrow. The most loaded portion of the limb 1, namely the intermediate portion 2, is made non-resilient, i.e. not bending, not changing its shape when the bowstring 10 is being drawn, and, consequently, it is not subjected to high wear during operation of the limb 1.
The upper portion 2, the intermediate portion 3 and the lower portion 4 of the limb 1 may be made as a single element, as shown in
Alternatively, the upper portion 2 and the lower portion 4 of the limb 1 may be made as individual members connected through the intermediate portion 2, as shown in
The limb 1 according to the invention may be not only curved, or extending in different directions (the upper portion 2 and the lower portion 4 of the limb 1 are arranged at an angle to each other even in complete absence of action from the bowstring 10), as shown in
The upper portion 2 and/or the lower portion 4 of the limb 1 may be made as one-piece members or may consist of several elements. For example, as shown in
Strengthening of the limb 1 in the region of the intermediate portion 3 by making the intermediate portion 3 non-resilient in conventional operation of the limb 1 enables to use practically the whole length of the limb 1 for accumulating energy and to ensure stability of the most loaded intermediate portion 3 at various loads. This principle may be applied to the limbs 1 of any shape, both unidirectional and extending in different directions.
The proposed limb and the bow or the crossbow featuring said limbs ensure a high speed of the arrow and a large stroke at small dimensions of the limb.
| Number | Name | Date | Kind |
|---|---|---|---|
| 2613660 | Bear | Oct 1952 | A |
| 3990425 | Ketchum | Nov 1976 | A |
| 4018205 | Meyer | Apr 1977 | A |
| 4183345 | Caldwell | Jan 1980 | A |
| 4227509 | Jones | Oct 1980 | A |
| 4258689 | Barnett | Mar 1981 | A |
| 4287867 | Islas | Sep 1981 | A |
| 5368006 | McPherson | Nov 1994 | A |
| 5388564 | Islas | Feb 1995 | A |
| 5706794 | Neal | Jan 1998 | A |
| 20100206284 | Popov et al. | Aug 2010 | A1 |
