Patent Grant
10605559
Professional archers often use a stabilizer with their bow to improve their accuracy. Similarly, hunters may also use a stabilizer as well. A stabilizer is typically screwed into an accessory hole on the bow, whether it by a compound or an Olympic bow. The stabilizer resists torque and absorbs vibrations in the bow when shot, thereby reducing the shock felt in the archer's hand on the bow grip. It also helps keep the bow balanced and settles the archer's arm during aiming.
Stabilizers are offered in different lengths and usually include adjustable weights so that they can be selected in accordance with particular preferences of the archer.
Bow stabilizers are well-known in the prior art as evidenced by the Stokes US patent application publication No. 2012/0240913. The stabilizer described in this publication includes a hollow, tubular elongated member which has first and second portions of different rigidity or stiffness along the length thereof. The first portion is adapted to flex in order to absorb shock when the bow is shot. The second portion is more stiff and the minimize movement when the bow is shot. Both portions include a core layer and a cover layer. However, in the first more flexible section, the cover layer is formed of a light fabric while in the second more stiff section, the cover layer is formed of a dense fabric.
While the prior stabilizers operate satisfactorily, they are limited in their ability to dampen vibrations. The core disclosed in Stokes is formed of a laminated carbon prepreg or other lightweight carbon or composite material including fiberglass, resin impregnated fabric, aluminum tubing or a combination of these materials. The cover material is a fabric, with the second section cover material being different and denser than the first section cover material. The second section cover material may include a layer of metal screen, foil or a thin metal tube in addition to the fabric material. However, whatever combination of materials is used is limited in its damping characteristics.
The stabilizer according to the invention includes an elongated member or tube formed of at least two layers of material which alternate in stiffness or rigidity from the core to the exterior.
In a first embodiment, two concentric layers of material are provided and extend continuously between the ends of the tube. The layers are formed of first and second materials having different degrees of stiffness or rigidity. One of the materials is a natural fiber, preferably flax. The other material is a metal, preferably a carbon fiber material. If the inner layer material has a high degree of stiffness, the outer layer material has a lower degree of stiffness relative to the inner layer. If the inner layer of material has low degree of stiffness, the outer layer material has a higher degree of stiffness relative to the inner layer.
In another embodiment, at least three layers of material are provided with some of the layers formed of a first material having a low degree of stiffness and one or more of the other layers formed of a second material having a higher degree of stiffness relative to the first degree of stiffness. If the innermost layer of the tube is formed of a low stiffness material, then it is surrounded by a layer of higher material which is in turn surrounded by a layer of the low stiffness material. Additional layers may be provided, but they preferably alternate in degrees of stiffness.
Alternatively, the innermost layer may be formed of the material of a higher degree of stiffness. In this case, the next outer layer is formed of a low stiffness material and the next outer layer is formed of a higher stiffness material.
The material having a low degree of stiffness is preferably a natural fiber material such as flax and the material having a higher degree of stiffness is preferably a composite and/or metal material such as carbon fiber.
Each layer of material may include sublayers of material having a similar degree of stiffness. Thus, at two adjacent layers of a material having a low degree of rigidity or stiffness may be covered by two or more layers of a material having a higher degree of stiffness which in turn are covered by two or more layers of material having a low degree of stiffness. In any case, at least three layers, whether they include a single layer or multiple sublayers, are provided with the layers alternating in degrees of stiffness from the core of the tube to the exterior of the tube.
Other objects and advantages of the invention will become apparent from a study of the following specification when viewed in the light of the accompanying drawing, in which:
The archery bow stabilizer 2 according to the disclosure as shown in
At one end, the tube includes a connector 6 including a threaded extension 8 coaxial with the member or tube for connecting the stabilizer with a bow (not shown). As is known in the art, the threaded extension is screwed into a threaded opening in the bow, although other types of connection may be provided. The connector is connected with an end of the member in a conventional manner such as via a plug-fit, weld or adhesive connection. At the other end of the member 4, and adjustable weight assembly 10 is connected with the member via a similar connection as the connector. The weight assembly includes a threaded member 12 which is coaxial with the member or tube for receiving a plurality of weights 14 having a central threaded opening. It will be apparent to those of ordinary skill in the art that the weight of the stabilizer can be adjusted according to the preferences of an archer by adding or removing weights 14 from the end of the stabilizer.
The member or tube of the stabilizer may be provided in different lengths. By way of example only, the length of the tube may be between eight and thirty-six inches, again depending on the preferences of the archer.
Referring now to
Examples of materials having a low degree of stiffness are natural fiber materials. A preferred material natural fiber material is flax, but other natural fibers may be used as well. These materials may be woven in a dry state of non-crimp unidirectional fabric and/or impregnated with other materials. By way of example only, a flax fiber linen dry fabric having a weight of 275 g/m2 has the following characteristics:
The natural fiber may also be reinforced with pre-impregnated composite materials. For example, such a material having a fabric weight of 3.2 oz/yd2 has the following characteristics:
The natural fiber may also be incorporated into a tape. For example, a composite made with twelve layers of natural fiber tape and an epoxy resin has the following characteristics:
The dampening ratio for the above composite natural fiber tape is 1.47%.
Examples of materials having a higher degree of stiffness are metals or composite materials such as fiberglass. Suitable metals are carbon and aluminum. According to a preferred embodiment, the material having a higher degree of stiffness is a carbon fiber, a high modulus carbon, or a woven carbon fiber such as carbon fiber twill. The tensile modulus of standard carbon materials is 33 msi and the tensile modulus of ultra-high modulus carbon is 110 msi. The dampening ratio of carbon is 0.18% and the dampening ratio of glass is 0.15%. Thus, the dampening ration of the natural fiber material is significantly higher than those of carbon or glass.
In the embodiment shown in
In the embodiment shown in
In the embodiment shown in
In the embodiment shown in
In each embodiment, the layers of material which form the member or tube are connected with each other using conventional techniques such as thermos-welding, adhesive, and the like. The outermost layer may be painted or otherwise coated to provide a desired appearance to the stabilizer.
Incorporating a natural fiber material into the stabilizer tube increases the damping ability of the stabilizer. By alternating natural fiber layers with harder metal layers, a composite stabilized with enhanced vibration reduction is provided. The ordering of the layers from the interior of the tube to the exterior is less significant than the alternate layering of stiff and less stiff materials totaling at least three layers.
While the preferred forms and embodiments of the archery stabilizer tube have been illustrated and described, it will be apparent to those of ordinary skill in the art that various changes and modifications may be made without deviating from the novel concepts thereof.
| Number | Name | Date | Kind |
|---|---|---|---|
| 4395159 | Karuks | Jul 1983 | A |
| 4840826 | Shirasaki | Jun 1989 | A |
| 6718964 | Graf | Apr 2004 | B1 |
| 6997174 | Sandberg | Feb 2006 | B2 |
| 9766033 | Powell | Sep 2017 | B2 |
| 20100084036 | Le Morvan | Apr 2010 | A1 |
| 20120240913 | Stokes | Sep 2012 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20190346230 A1 | Nov 2019 | US |
