TIRE AND A RUBBER PLY FOR A TIRE

Abstract

The present invention is directed to a rubber ply for a tire, the rubber ply comprising pairs of textile cords arranged in parallel in a plane, wherein each cord of the pairs of textile cords comprises two cord plies. The distance between two adjacent pairs of textile cords (d.sub.p) is at least 5 times larger than the distance between two parallel textile cords (d.sub.i) within a pair of textile cords, and wherein the two cord plies in one or more of the textile cords are twisted together in a range from 8 TPI to 12 TPI and have each a density ranging from 500 dtex to 2000 dtex. The present invention is also directed to a tire comprising such a rubber ply which is particularly applicable and beneficial for utilization in motorcycle tires.

Claims

1. A rubber ply for a tire, the rubber ply comprising pairs of textile cords arranged in parallel in a plane, with each cord of the pairs of textile cords comprising two cord plies, wherein the distance between two adjacent pairs of textile cords (d.sub.p) is at least five times larger than the distance between two parallel textile cords (d.sub.i) within a pair of textile cords, and wherein the two cord plies in one or more of the textile cords are twisted together in a range from 8 twists per inch to 12 twists per inch and wherein the cord plies have a density ranging from 500 dtex to 2000 dtex.

2. The rubber ply of claim 1 wherein the distance between two adjacent pairs of textile cords (dp) corresponds to 40% to 300% of a maximum diameter of the cords of said adjacent pairs of textile cords.

3. The rubber ply of claim 1 wherein the distance between two parallel textile cords (di) within a pair of textile cords is smaller than 30% of a maximum diameter of a cord of said pair of textile cords.

4. The rubber ply of claim 1 wherein the number of textile cords measured in parallel to the plane and perpendicular to a length of the textile cords ranges from 25 EPI to 40 EPI.

5. The rubber ply of claim 3 wherein the number of textile cords measured in parallel to the plane and perpendicular to a length of the cords ranges from 30 EPI to 38 EPI.

6. The rubber ply of claim 1 wherein two cord plies of the textile cords are twisted together in a range from 9 twists per inch to 11 twists per inch to form together a cord.

7. The rubber ply of claim 1 wherein the density is ranging from 900 dtex to 1450 dtex.

8. The rubber ply of claim 1 wherein the textile cords are made of Nylon 6,6.

9. The rubber ply of claim 1 wherein the distance between two adjacent pairs of textile cords (dp) ranges from 0.15 mm to 1.5 mm.

10. The rubber ply of claim 1 wherein the distance between two adjacent pairs of textile cords (dp) ranges from 0.2 mm to 1.0 mm.

11. The rubber ply of claim 1 wherein the distance between two parallel textile cords (di) within a pair of textile cords is smaller than 0.15 mm.

12. The rubber ply of claim 1 wherein the rubber ply is a rubber ply strip having one or more of: a width (w) ranging from 0.5 cm to 2 cm and a thickness (t) ranging from 0.4 mm to 2 mm.

13. The rubber ply of claim 11 wherein the rubber ply strip has one or more of: a width (w) ranging from 0.5 cm to 1.5 cm and a thickness (t) ranging from 0.5 mm to 1.5 mm.

14. The rubber ply of claim 1 wherein the rubber ply is an overlay ply strip.

15. The rubber ply of claim 1 wherein the ratio of rubber to textile cords by weight ranges from 2.3:1 to 1.1:1.

16. The rubber ply of claim 1 wherein the ratio of rubber to textile cords by weight ranges from 2.0:1 to 1.5:1.

17. The rubber ply of claim 1 wherein each cord ply has a plurality of filaments.

18. A tire comprising two spaced apart bead portions, a tread portion, a pair of sidewalls extending from axially outer edges of the tread portion to join the respective bead portions, a carcass, at least one belt ply covering the carcass, and an overlay ply strip spirally arranged in a circumferential plane between the tread and the at least one belt ply, wherein the cords are arranged essentially in parallel to the length of the strip, wherein at least one of the belt ply and the overlay ply is comprised of a rubber ply comprising pairs of textile cords arranged in parallel in a plane, each cord of a pair of textile cords comprising two cord plies, wherein the distance between two adjacent pairs of textile cords (dp) is at least 5 times larger than the distance between two parallel textile cords within a pair of textile cords (di), and wherein the two cord plies in one or more of the textile cords are twisted together in a range from 8 twists per inch to 12 twists per inch and have each a density ranging from 500 dtex to 2000 dtex.

19. The tire of claim 18 wherein the strip is arranged at an angle ranging from 0° to 5° with respect to the equatorial plane (EP) of the tire.

20. The tire of claim 19 wherein the at least one belt ply comprises a textile cord reinforcement.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The structure, operation and advantages of the invention will become more apparent upon contemplation of the following description taken in conjunction with the accompanying drawings

[0029] FIG. 1 illustrates a schematic cross section of a motorcycle tire comprising a spirally wound overlay ply strip in accordance with an embodiment of the present invention.

[0030] FIG. 2 illustrates a schematic cross section of a rubber ply strip in accordance with another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0031] FIG. 1 is a schematic cross-section of a motorcycle tire 1, in accordance with a non-limiting embodiment of this invention. The example tire 1 has a tread 2 having a plurality of grooves 3, a belt structure comprising two belt plies 8, 9, a carcass ply 5, two sidewalls, and two bead regions 4 comprising bead filler apexes 7 and beads 6. The carcass ply 5 includes a pair of axially opposite end portions, each of which is associated with a respective one of the beads 6. Each axial end portion of the carcass ply 5 may be turned up and around the respective bead 6 to a position to anchor each axial end portion. As further shown in FIG. 1, the belt plies 8, 9 are covered by an overlay ply strip 10. In the present example, the overlay ply strip 10 is spirally wound around the belt ply 9 at an angle of less than 5° with respect to the equatorial plane of the tire EP. The overlay ply strip 10 can be spirally wound around the belt ply 9 at an angle of less than 4°, 3°, 2°, or even 1° with respect to the equatorial plane of the tire EP. The overlay strip 10 comprises multiple parallel pairs of textile cords. While the drawing schematically indicates that the ply 10 does not overlap in the axial direction a, such an overlap may be present in practice and in another embodiment. For the sake of better comprehensibility, the axial direction a, the circumferential direction c and the radial direction r have been indicated in FIG. 1 as commonly used in the description of tire geometries.

[0032] FIG. 2 shows a detailed schematic cross section of another rubber ply strip 10′ in accordance with another embodiment of the present invention. The example strip has three pairs 20 of cords 22, wherein each cord 22 is made of two cord plies 24. The cord plies 24 are twisted together to form a cord 22. The distance d.sub.p between two pairs 20 of cords 22 is considerably larger than the distance d.sub.i between two cords 22 of one pair 20. In the present example, the distance d.sub.p is about 7 times larger than the distance d.sub.i. The three pairs 20 of cords 22 are embedded over the width w of the strip 10′ which has the thickness t. Due to the paired arrangement of the cords 22, it is possible to provide a relatively thin strip with a limited amount of rubber material.

[0033] In particular, each cord 22 comprises or consists of two cord plies 24 twisted together with 8 TPI to 12 TPI, wherein each yarn 24 has a linear density ranging from 500 dtex to 2000 dtex. Preferred examples could for instance have a linear density of 1400 dtex per cord ply 24 at 9.3 TPI (i.e. a 1400/2 9.3×9.3 cord construction). The strip 10′ could for instance have 31 EPI, measured perpendicular to the length of the strip and assuming that the cords 22 are arranged essentially in parallel to the length of the strip 10′ within the strip 10′. In another preferred example, a cord 22 could have the construction 940/2 10.8×10.8 TPI, with 36 EPI measured over the width w of the strip 10′. Each cord 22 of a pair 20 of cords 22 is counted separately when referring to EPI values herein.

[0034] In general, rubber material can also be understood herein as an elastomeric material. Any rubber composition commonly used in tire plies or ply strips, in particular in overlay strips, can be used. In particular, the rubber ply can be a cured rubber ply, as common in tire technology.

[0035] While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention.