Multilayer composite limbs for an archery bow

• US 8,635,994 B1
• Filed: 10/19/2009
• Issued: 01/28/2014
• Est. Priority Date: 10/19/2009
• Status: Active Grant

• Current Assignee: Bowtech, Inc.
• Original Assignee: Bowtech, Inc.
• Inventors: Yehle, Craig T.
• Primary Examiner(s): Kim, Gene
• Assistant Examiner(s): KLAYMAN, AMIR ARIE
• Application Number:
  US12/581,818
• Time in Patent Office: 1,562 Days
• Field of Search: 124/23.1
• US Class Current: 124/23.1
• CPC Class Codes: F41B 5/0068 laminated

Abstract

An archery bow comprises a central riser, first and second bow limbs attached to the riser, and a draw cable coupled to the bow limbs. Each bow limb comprises a multilayer composite structure having a compression layer, a tension layer, and an intermediate layer between the compression and tension layers, with the limbs arranged so that drawing the bow causes each limb to bend toward its corresponding compression layer. Each layer comprises corresponding fibers embedded in a corresponding polymer matrix. Elastic moduli of the compression and tension layers are each smaller than that of the intermediate layer. A method comprises attaching the first and second bow limbs to the riser and coupling the draw cable to the limbs. Another method can further comprise forming each bow limb by embedding the corresponding fibers of each layer in the corresponding polymer matrix, and curing the corresponding polymer matrix.

Claims

1. An archery bow comprising:

a central riser;

first and second bow limbs attached to the riser; and

a draw cable coupled to the first and second bow limbs, the bow limbs and draw cable being arranged so that pulling the draw cable to draw the bow causes the first and second bow limbs to bend toward one another,

wherein;

each of the first and second bow limbs comprises a multilayer composite structure having a compression layer, a tension layer, and an intermediate layer between the compression and tension layers, each of said layers comprising corresponding fibers embedded in a corresponding polymer matrix;

the first and second bow limbs are arranged on the bow so that drawing the bow causes each limb to bend toward its corresponding compression layer; and

the compression and tension layers each have a respective elastic modulus smaller than an elastic modulus of the intermediate layer; and

wherein;

the compression layer comprises multiple sublayers having differing elastic moduli;

the intermediate layer comprises multiple sublayers having differing elastic moduli;

or the tension layer comprises multiple sublayers having differing elastic moduli.

2. The bow of claim 1 further comprising:

first and second pulley members rotatably mounted on the first and second bow limbs, respectively, the pulley members being arranged to couple the draw cable to the first and second bow limbs and to rotate and let out the draw cable as the bow is drawn; and

at least one additional cable coupled to the first and second bow limbs and arranged to be taken up or let out by at least one of the pulley members as the bow is drawn.

3. The bow of claim 1 wherein each bow limb comprises a pair of limb members arranged side-by-side.

4. The bow of claim 1 wherein the fibers of the intermediate layer comprise a material that differs from that of the fibers of the compression layer or the fibers of the tension layer.

5. The bow of claim 1 wherein:

the polymer matrix of the compression layer comprises epoxy, polyurethane, polyester, or polyvinyl ester;

the polymer matrix of the intermediate layer comprises epoxy, polyurethane, polyester, or polyvinyl ester; and

the polymer matrix of the tension layer comprises epoxy, polyurethane, polyester, or polyvinyl ester.

6. The bow of claim 1 wherein:

the fibers of the compression layer comprise boron, aramid, polyester, silica, basalt, liquid crystal polymer, glass, carbon, or nanotubes;

the fibers of the intermediate layer comprise boron, aramid, polyester, silica, basalt, liquid crystal polymer, glass, carbon, or nanotubes; and

the fibers of the tension layer comprise boron, aramid, polyester, silica, basalt, liquid crystal polymer, glass, carbon, or nanotubes.

7. The bow of claim 1 wherein the compressive layer includes glass fibers, the intermediate layer includes graphite fibers, and the tension layer includes glass fibers.

8. The bow of claim 7 wherein:

a weight percent of fibers in the compression layer is between about 40% and about 75%;

a weight percent of fibers in the intermediate layer is between about 40% and about 85%; and

a weight percent of fibers in the tension layer is between about 40% and about 75%.

9. The bow of claim 7 wherein the compression layer includes epoxy polymer matrix, the intermediate layer includes epoxy polymer matrix, and the tension layer includes epoxy polymer matrix.

10. The bow of claim 7 wherein, over at least an intermediate portion of the length of each bow limb:

the compression layer is between about 0.03 inches thick and about 0.15 inches thick;

the intermediate layer is between about 0.03 inches thick and about 0.50 inches thick; and

the tension layer is between about 0.03 inches thick and about 0.15 inches thick.

11. The bow of claim 7 wherein:

the elastic modulus of the compression layer is between about 3 Mpsi and about 10 Mpsi;

the elastic modulus of the intermediate layer is between about 6 Mpsi and about 25 Mpsi; and

the elastic modulus of the tension layer is between about 3 Mpsi and about 10 Mpsi.

12. The bow of claim 7 wherein, over at least an intermediate portion of the length of each bow limb, the compression layer is thicker than the tension layer.

13. A method for constructing an archery bow, the method comprising:

attaching first and second bow limbs to a central riser; and

coupling a draw cable to the first and second bow limbs and arranging the bow limbs and draw cable so that pulling the draw cable to draw the bow causes the first and second bow limbs to bend toward one another,

wherein;

each of the first and second bow limbs comprises a multilayer composite structure having a compression layer, a tension layer, and an intermediate layer between the compression and tension layers, each of said layers comprising corresponding fibers embedded in a corresponding polymer matrix;

the first and second bow limbs are arranged on the bow so that drawing the bow causes each limb to bend toward its corresponding compression layer; and

the compression and tension layers each have a respective elastic modulus smaller than an elastic modulus of the intermediate layer; and

wherein;

the compression layer comprises multiple sublayers having differing elastic moduli;

the intermediate layer comprises multiple sublayers having differing elastic moduli;

or the tension layer comprises multiple sublayers having differing elastic moduli.

14. The method of claim 13 further comprising forming each bow limb by:

embedding the corresponding fibers of each layer in the corresponding polymer matrix; and

curing the corresponding polymer matrix.

15. The method of claim 14 further comprising assembling the compression layer, the intermediate layer, and the tension layer before curing the corresponding polymer matrices.

16. The method of claim 13 further comprising:

rotatably mounting first and second pulley members on the first and second bow limbs, respectively, and arranging the pulley members to couple the draw cable to the first and second bow limbs and to rotate and let out the draw cable as the bow is drawn; and

coupling at least one additional cable to the first and second bow limbs and arranging each additional cable to be taken up or let out by at least one of the pulley members as the bow is drawn.

17. The method of claim 13 wherein each bow limb comprises a pair of limb members arranged side-by-side.

18. The method of claim 13 wherein the fibers of the intermediate layer comprise a material that differs from that of the fibers of the compression layer or the tension layer.

19. The method of claim 13 wherein:

the polymer matrix of the compression layer comprises epoxy, polyurethane, polyester, or polyvinyl ester;

the polymer matrix of the intermediate layer comprises epoxy, polyurethane, polyester, or polyvinyl ester; and

the polymer matrix of the tension layer comprises epoxy, polyurethane, polyester, or polyvinyl ester.

20. The method of claim 13 wherein:

the fibers of the compression layer comprise boron, aramid, polyester, silica, basalt, liquid crystal polymer, glass, carbon, or nanotubes;

the fibers of the intermediate layer comprise boron, aramid, polyester, silica, basalt, liquid crystal polymer, glass, carbon, or nanotubes; and

the fibers of the tension layer comprise boron, aramid, polyester, silica, basalt, liquid crystal polymer, glass, carbon, or nanotubes.

21. The method of claim 13 wherein the compressive layer includes glass fibers, the intermediate layer includes graphite fibers, and the tension layer includes glass fibers.

22. The method of claim 21 wherein:

a weight percent of fibers in the compression layer is between about 40% and about 75%;

a weight percent of fibers in the intermediate layer is between about 40% and about 85%; and

a weight percent of fibers in the tension layer is between about 40% and about 75%.

23. The method of claim 21 wherein the compression layer includes epoxy polymer matrix, the intermediate layer includes epoxy polymer matrix, and the tension layer includes epoxy polymer matrix.

24. The method of claim 21 wherein, over at least an intermediate portion of the length of each bow limb:

the compression layer is between about 0.03 inches thick and about 0.15 inches thick;

the intermediate layer is between about 0.03 inches thick and about 0.50 inches thick; and

the tension layer is between about 0.03 inches thick and about 0.15 inches thick.

25. The method of claim 21 wherein:

the elastic modulus of the compression layer is between about 3 Mpsi and about 10 Mpsi;

the elastic modulus of the intermediate layer is between about 6 Mpsi and about 25 Mpsi; and

the elastic modulus of the tension layer is between about 3 Mpsi and about 10 Mpsi.

26. The method of claim 21 wherein, over at least an intermediate portion of the length of each bow limb, the compression layer is thicker than the tension layer.