LIGHTWEIGHT BEAD FOR A TIRE

Abstract

A bead for a tire in accordance with the present invention includes a core with at least one yarn of a multifilament textile fiber embedded in an organic matrix having a density between 0.9 g/m.sup.3 and 2.0 g/m.sup.3 and an outer sheath layer including at least one metal wire wound around, and in contact with, the core. The core has a diameter between 5.0 mm and 30.0 mm.

Claims

1. A bead for a tire comprising: a core including at least one yarn of a multifilament textile fiber embedded in an organic matrix having a density between 0.9 g/m.sup.3 and 2.00 g/m.sup.3, the core having a diameter between 5.0 mm and 30.0 mm; and an outer sheath layer including at least one metal wire wound around and in contact with the core.

2. The bead as set forth in claim 1 wherein the core includes a single yarn of the multifilament textile fiber.

3. The bead as set forth in claim 1 wherein the core includes a plurality of separate yarns of the multifilament textile fiber.

4. The bead as set forth in claim 1 wherein each yarn of the multifilament textile fiber has a yield strength greater than 2000 MPa.

5. The bead as set forth in claim 1 wherein each yarn of the multifilament textile fiber has a Young's modulus less than or equal to 300 GPa.

6. The bead as set forth in claim 1 wherein a ratio of a mass of the core to a mass of the bead is less than 0.6.

7. The bead as set forth in claim 6 wherein the ratio of the force at break of the bead core to the force at break of the bead is greater than or equal to 0.25.

8. The bead as set forth in claim 1 wherein a contribution of the core to a force at break of the entire bead is between 5 percent and 60 percent.

9. The bead as set forth in claim 8 wherein the contribution of the core to the force at break of the bead is between 5 percent and 30 percent.

10. The bead as set forth in claim 1 wherein a ratio of a mass of the core to a mass of the bead is between 40 percent and 60 percent.

11. The bead as set forth in claim 10 wherein the ratio of the mass of the core to the mass of the bead is greater than or equal to 0.05.

12. The bead as set forth in claim 1 wherein a ratio of the diameter of the core to a diameter of a bead is greater than or equal to 0.4.

13. The bead as set forth in claim 1 wherein the bead core has an ultimate break strength greater than or equal to 200 MPa.

14. The bead as set forth in claim 1 wherein a diameter of each yarn of the multifilament textile fiber is between 0.5 mm and 6.0 mm.

15. The bead as set forth in claim 1 wherein a diameter of each elementary filament of each multifilament textile fiber is between 2.0 m and 30.0 m.

16. The bead as set forth in claim 1 wherein each multifilament textile fiber is continuous.

17. The bead as set forth in claim 1 wherein each multifilament textile fiber includes more than 10 elementary filaments.

18. The bead as set forth in claim 1 wherein each multifilament textile fiber is chosen from a group of fibers consisting of: glass fibers, carbon fibers, polyphenylene benzobisoxazole (PBO), silica fibers, ceramic fibers, and mixtures thereof.

19. The bead as set forth in claim 1 wherein the organic matrix is a thermoset type of matrix.

20. A tire comprising at least one bead, each bead including a core that includes at least one yarn of a multifilament textile fiber embedded in an organic matrix having a density between 0.9 g/m.sup.3 and 2.0 g/m.sup.3 and an outer layer that includes a metal wire wound around, and in contact with, the core, the core having a diameter between 5.0 mm and 30.0 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The present invention will be better understood on reading the following description, which is given solely by way of nonlimiting example, with reference to the drawings, in which:

[0056] FIG. 1 is a schematic cross-sectional view of a tire for use with the present invention;

[0057] FIG. 2 is a schematic cross-sectional view of a bead according to one example of the present invention; and

[0058] FIG. 3 is a schematic cross-sectional view of a bead according to one example of the present invention.

DESCRIPTION OF EXAMPLES OF THE PRESENT INVENTION

[0059] FIG. 1 shows a tire 10, pneumatic or non-pneumatic, for use with the present invention. As an example, the tire 10 may be a tire for an aircraft. The tire 10 may have a crown 12 reinforced by a crown reinforcement, or belt structure 14; two sidewalls 16; and two annular beads 120. The crown 12 may be surmounted by a tread, not shown in this schematic figure. A carcass reinforcement 22 may be wound around the two beads 120 and include a turn-up 24 disposed towards the outside of each bead 120 fitted onto a wheel rim 26. The carcass reinforcement 22 may include at least one ply reinforced with radial cords. Each bead 120 may have a toroidal overall shape with an approximately circular cross section (FIGS. 2-3). Alternatively, the bead 120 may have a square, rectangular, hexagonal, and/or other polygon cross section or an elliptical or oblong cross section (not shown).

[0060] As shown in FIG. 2, another bead 220 may include a core 230 and an outer sheath layer 240. The bead core 230 may have a circular cross-section and a single core. The bead core 30 may include a single yarn forming a monolithic torus. The core 230 may have an approximately circular cross section and an exemplary diameter between 7.0 mm and 10.00 mm, or about 8.90 mm. The core 230 may include a multifilament textile fiber embedded in an organic matrix. The multifilament textile fiber of the core 230 may be a glass fiber and the organic core matrix may be a thermoset resin. The multifilament textile fiber of the core 230 may be continuous or discontinuous. The glass fiber of the core 230 may include more than 1000 elementary glass filaments arranged side by side and parallel to one another, apart from an occasional overlap. The diameter of each elementary filament of the textile fiber of the core 230 may be between 2.0 m and 30.0 m. The thermoset resin may be of the vinyl ester type, such as an epoxy vinyl ester. The core 230 may be manufactured by impregnation of the fiber, such as described in U.S. Pat. No. 3,730,678, incorporated herein by reference in its entirety, or by injection of the organic matrix into a mold in which the fiber has previously been placed, such as described in document U.S. Pat. No. 7,032,637, incorporated herein by reference in its entirety.

[0061] The sheath layer 240 of the bead 220 may include one or more metal wires (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more, etc.) wound in a helix around the core 230. The wire(s) of the sheath layer 240 may be wound around, and in contact with, the core 230 and have a circular cross-section with a diameter between 1.0 mm and 2.0 mm, or 1.30 mm. The wire(s) of the sheath layer 240 may be made a steel with a carbon content less than 0.9 percent, by weight of steel. The wire(s) of the sheath layer 240 may be wound over one or more turns, such as between 6 and 10 turns, or 8 turns. The sheath layer 240 may saturated. The two ends of the wire of the sheath layer 240 may be connected by means of a sleeve (not shown).

[0062] Still another bead 320 for use with the present invention may include a core 330 with three coils 335, each of a single yarn. Each of the three coils 335 may include a single yarn forming three separate monolithic torusses wound (e.g. twisting, cabling. etc.) about each other. Each of the three coils 335 of the core 330 may have a circular cross section with an exemplary diameter between 7.0 mm and 10.0 mm, or 8.9 mm. Each of the coils 335 may include a multifilament textile fiber embedded in an organic matrix. As described above, the multifilament textile fiber of the core 330 may be a glass fiber and the organic core matrix may be a thermoset resin. The multifilament textile fiber of the core 330 may be continuous or discontinuous. The glass fiber of the core 330 may include more than 1000 elementary glass filaments arranged side by side and parallel to one another, apart from an occasional overlap. The diameter of each elementary filament of the textile fiber of the core 330 may be between 2.0 m and 30.0 m. The thermoset resin may be of the vinyl ester type, such as an epoxy vinyl ester. The core 330 may be manufactured by impregnation of the fiber, such as described in U.S. Pat. No. 3,730,678, incorporated herein by reference in its entirety, or by injection of the organic matrix into a mold in which the fiber has previously been placed, as described in U.S. Pat. No. 7,032,637, incorporated herein by reference in its entirety.

[0063] Traverse winding of each coil 335 over a number of turns may be carried out such that the core 330 has a substantially triangular cross section (FIG. 3) with a diameter of each coil between 0.5 mm and 3.0 mm, or between 1.0 mm and 2.0 mm, or 1.5 mm. A diameter of the torus defined by the bead 320 may be between 4.0 mm and 8.0 mm, or 5.8 mm. The diameter of the torus defined by the core 330 may be between 2.0 mm and 5.0 mm, or 3.28 mm. The wire of the sheath 340 may have a diameter between 1.0 mm and 3.0 mm, or 1.5 mm.

[0064] The sheath layer 340 may include one or more metal wires (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10 or more, etc.) wound in a helix around the core 330. A single wire of the sheath layer 340 may be wound around, and in contact with, the core 330 and have a circular cross-section with a diameter between 1.0 mm and 2.0 mm, or 1.30 mm. The single wire of the sheath layer 40 may be a steel with a carbon content greater than or equal to 0.9 percent, by weight of the steel. The wire of the sheath layer 340 may be wound over one or more turns, such as between 6 and 10 turns, or 8 turns. The sheath layer 340 may saturated. The two ends of the wire of the sheath layer 340 may be connected by means of a sleeve (not shown).

[0065] Alternatively, as shown in FIG. 3, another bead 320 for use with the present invention may include a core 330 with three coils 335, each of a single yarn. Each of the three coils 335 may include a single yarn forming three separate monolithic torusses extending parallel to each other. Each of the three coils 335 of the core 330 may have a circular cross section with an exemplary diameter between 7.0 mm and 10.0 mm, or 8.9 mm. Each of the coils 335 may include a multifilament textile fiber embedded in an organic matrix. As described above, the multifilament textile fiber may be a glass fiber and the organic core matrix may be a thermoset resin. The multifilament textile fiber may be continuous or discontinuous. The glass fiber may include more than 1000 elementary glass filaments arranged side by side and parallel to one another, apart from an occasional overlap. The diameter of each elementary filament of the textile fiber may be between 2.0 m and 30.0 m. The thermoset resin may be of the vinyl ester type, such as an epoxy vinyl ester. The core 30 may be manufactured by impregnation of the fiber, as described in document U.S. Pat. No. 3,730,678, incorporated herein by reference in its entirety, or by injection of the organic matrix into a mold in which the fiber has previously been placed, as described in document U.S. Pat. No. 7,032,637, incorporated herein by reference in its entirety.

[0066] Traverse winding of each coil 335 over a number of turns may be carried out such that the core 30 has a substantially polygonal, in this case triangular cross section (FIG. 3) with a diameter of each coil between 0.5 mm and 3.0 mm, or between 1.0 mm and 2.0 mm, or 1.5 mm. A diameter of the torus defined by the bead 320 may be between 4.0 mm and 8.0 mm, or 5.8 mm. The diameter of the torus defined by the core 330 may be between 2.0 mm and 5.0 mm, or 3.28 mm. The wire of the sheath 340 may have a diameter between 1.0 mm and 3.0 mm, or 1.5 mm.

[0067] The beads 120, 220, 320 according to the present invention may be fitted on any type of tire. For example, the bead may be intended for a tire for industrial vehicles chosen from vans, heavy vehicles (e.g., metro vehicles, buses, road transport vehicles (lorries, tractors, trailers), off-road vehicles, aircraft, agricultural, and/or construction plant machinery, and other transport or handling vehicles. Further, the characteristics of the beads 120, 220, 320 may be mixed and/or combined with one another in any suitable way compatible with one another.

[0068] In accordance with the present invention, the cores 30, 230, 330 may have a diameter between 5.0 mm and 30.0 mm, or 6.0 mm and 8.0 mm, or 7.0 mm. This larger diameter of the cores 30, 230, 330 thereby allows the further reduction of the weight of the beads 20, 220, 320 of the tire 10. As described above, the wire of the sheaths 40, 240, 340 may have a diameter between 1.0 mm and 3.0 mm, or 1.5 mm. Aluminum generally may have a density of 2.71 g/m.sup.3 whereas the polymeric resin system of the cores 30, 230, 330 may be generally between 0.5 g/m.sup.3 and 2.0 g/m.sup.3, or 0.9 g/m.sup.3 and 2.0 g/m.sup.3, or 0.9 g/m.sup.3 and 1.8 g/m.sup.3, or 1.74 g/m.sup.3. Thus, a 35 percent reduction in weight or the same sized cores may be achieved. Further, the break strength of aluminum may be 1,360 ft*lb whereas the polymeric resin may be 4300 ft*lb. The molding process may also provide a perfectly continuous structure with no aluminum welding, which is the current practice for aluminum core production.

[0069] While the present invention has been described in connection with what is considered the most practical examples, it is to be understood that the present invention is not to be limited to the disclosed arrangements, but is intended to encompass various arrangements which are included within the spirit and scope of the broadest possible interpretation of the appended claims so as to include all possible modifications and equivalent arrangements. Numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the present invention may be practiced otherwise than as specifically and exemplarily described herein.