SHEARBAND STRUCTURE FOR A TIRE

Abstract

A tire includes a carcass ply, a tread disposed radially outward of a crown region of the carcass ply, and a shearband structure having an overall axial width substantially equal to a tread width interposed between the tread and the crown region in circumferential surrounding relation to the carcass ply. The shearband structure includes a first shearband layer and a second shearband layer radially adjacent the first shearband layer. The first shearband layer includes a first reinforced composite with first reinforcement cords embedded in a first rubber matrix. The first reinforcement cords have having an aramid construction and a twist multiplier (TM) between 2.0 and 6.0.

Claims

1. A tire comprising: a carcass ply; a tread disposed radially outward of a crown region of the carcass ply; and a shearband structure having an overall axial width substantially equal to a tread width interposed between the tread and the crown region in circumferential surrounding relation to the carcass ply, the shearband structure including a first shearband layer and a second shearband layer radially adjacent the first shearband layer, the first shearband layer including a first reinforced composite with first reinforcement cords embedded in a first rubber matrix, the first reinforcement cords having an aramid construction and a twist multiplier (TM) between 2.0 and 6.0.

2. The tire as set forth in claim 1 wherein the second shearband layer includes a second reinforced composite with second reinforcement cords embedded in a second rubber matrix, the second reinforcement cords having an aramid construction and a twist multiplier (TM) between 2.0 and 6.0.

3. The tire as set forth in claim 1 wherein the first reinforcement cords have a Z twist between 100 TPM and 300 TPM.

4. The tire as set forth in claim 3 wherein the first reinforcement cords have a S twist of between 100 TPM and 300 TPM.

5. The tire as set forth in claim 2 wherein the second reinforcement cords have a Z twist between 100 TPM and 300 TPM.

6. The tire as set forth in claim 5 wherein the second reinforcement cords have a S twist between 100 TPM and 300 TPM.

7. The tire as set forth in claim 1 wherein the first reinforcement cords have a density within the first rubber matrix between 15 EPI and 35 EPI.

8. The tire as set forth in claim 7 wherein the first reinforcement cords have a density within the first rubber matrix between 22 EPI and 25 EPI.

9. The tire as set forth in claim 8 wherein the first reinforcement cords have a density within the first rubber matrix of about 28 EPI.

10. The tire as set forth in claim 1 wherein the second reinforcement cords have a density within the second rubber matrix between 15 EPI and 35 EPI.

11. The tire as set forth in claim 10 wherein the second reinforcement cords have a density within the second rubber matrix between 22 EPI and 25 EPI.

12. The tire as set forth in claim 11 wherein the second reinforcement cords have a density within the second rubber matrix of about 28 EPI.

13. The tire as set forth in claim 1 wherein the first reinforcement cords are formed from aramid.

14. The tire as set forth in claim 1 wherein the second reinforcement cords are formed from aramid.

15. The tire as set forth in claim 1 wherein the first and second reinforcement cords are both formed only from aramid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0098] The present invention will be described by way of example and with reference to the accompanying drawings in which:

[0099] FIG. 1 is a cross-sectional view of an example tire for use with the present invention;

[0100] FIG. 2 is a cross-sectional view of another example tire for use with the present invention;

[0101] FIG. 3 is a perspective view of a shearband composite in accordance with the present invention; and

[0102] FIG. 4 is a table of properties of some example cord structures in accordance with the present invention

DETAILED DESCRIPTION OF EXAMPLES OF THE PRESENT INVENTION

[0103] With reference to FIG. 1, there is represented an example tire 10, pneumatic or non-pneumatic, for use with the present invention. The tire 10 may have a pair of substantially inextensible bead cores 11, 12 axially spaced apart with two carcass plies 13, 14 extending between the bead cores. The carcass plies may be folded axially and radially outward about each of the bead cores 11, 12 and be reinforced by cords substantially parallel to each other in the same ply at an angle of 50° to 90° with respect to the equatorial plane (EP) of the tire 10. Cords belonging to adjacent carcass plies 13, 14 may generally have opposite angles crossing each other at an angle of at an angle of 2 degrees to 5 degrees. The cords of the carcass plies 13, 14 may be any suitable material, such as steel, nylon, rayon, aramid, and/or polyester. The tire 10 may have carcass plies 13,14 of side-by-side polyester or rayon cables and a crown area 20 reinforced by a shearband assembly 21 located radially inward of the tire tread 22. The tire 10 may have an aspect ratio between 25 and 65.

[0104] The tire 10 may further include a shearband structure 30 with an essentially rigid folded shearband 23 and a cut shearband 24 disposed radially outward of the folded shearband. Both shearbands 23, 24 may be reinforced with aramid cables or yarns. The shearbands 23, 24 may have identical or different constructions. Such cords may be treated (coated) with one or more layers of adhesive in a process known as dipping. The modulus of a treated cord may be a function of the twist of the different yarns used in the cord, the cord twist, and the manner that the cord is subjected to the dipping operation.

[0105] Cords of the folded shearband 23 may be substantially parallel to each other and make an angle of 15° to 40° with respect to the equatorial plane (EP) of the tire 10. The axially outer portions of the folded shearband 23 may be folded back on both lateral sides in a radially outward direction over axial edges of the cut shearband 24 with the folded portions 25, 26 being symmetrical with respect to the equatorial plane (EP). The folded portions 25, 26 may each have a transverse width between 5% and 30%, or 15% and 30% of the tread width (TW).

[0106] As shown in FIG. 2, another example tire 10a, for use with the present invention, may include one carcass ply 13a wrapped around beads 11a,12a. The shearband structure 30 may include shearbands 16, 17 reinforced with aramid cords and overlays 27, 28 disposed radially outward of the shearbands 16, 17. The shearbands 16, 17 may have identical or different constructions. The overlays 27, 28 may be single sheets of overlay material, a cut overlay (e.g., reinforcement cords in the overlay discontinuous at random locations throughout the tire), and/or a spiral overlay. The reinforcing cords in the overlay 27, 28 may comprise nylon, polyester, polyamine, aramid, and/or any other suitable overlay reinforcement material.

[0107] As shown in FIG. 3, in accordance with the present invention, the shearbands 16, 17, 23, 24 of the shearband structure 30 may include a reinforced composite with compression resistant reinforcement cords 31 of aramid embedded in a rubber matrix 32. The compression resistant reinforcement cords 31 may be yarns of aramid having their component filaments twisted together a given number of turns per unit of length of the yarn (usually expressed in turns per inch, TPI, or in turns per meter, TPM). The aramid yarns may be twisted together to form a cord 31 with a twist level.

[0108] A first example compression resistant aramid reinforcement cord 31 for the shearband structure 30 may have a 1100/4 dtex construction and a cord distribution density of 15 ends per inch (EPI) to 35 EPI, or 22 EPI to 25 EPI, or 28 EPI. The first reinforcement cord 31 may have a twist between Z150/S150 turns per meter (TPM) and Z200/S200 TPM, or about Z180/S180 TPM, and a tension between 100 mN/tex and 200 mN/tex, or about 180 mN/tex, or about 120 mN/tex.

[0109] A second example compression resistant aramid reinforcement cord 31 for the shearband structure 30 may have a 1210/3 dtex construction and a cord distribution density of 15 ends per inch (EPI) to 35 EPI, or 22 EPI to 25 EPI, or 28 EPI. The second reinforcement cord 31 may have a twist between Z150/S150 turns per meter (TPM) and Z250/S250 TPM, or about Z200/S200 TPM, and a tension between 100 mN/tex and 150 mN/tex, or about 120 mN/tex.

[0110] As stated above, aramid shearband structures may be used in place of steel shearbands to reduce weight. Steelwire has limited compression resistance. However, twisted aramid cords may provide higher compression resistance compared to steelwire. To maximize its benefits, compression resistant aramid cords may essentially mimic steel shearband wires' stress-strain curves. The gauge of the aramid cords may also be similar to the targeted steel wire gauge. Such “lower twist” aramid cord constructions may provide higher tensions for a stiff, steelwire-like, dipped aramid cord.

[0111] As shown in FIG. 4, these aramid cords may have a twist multiplier TM in a range of 2.00 to 6.00, or 2.98 to 4.97. These cords may be tensioned in two of more different zones. These cords may replace steelwire in shearband structures of non-pneumatic tires or in spiral cord, 0 degree and/or angled shearbands. These cords may exhibit up to six times the durability of steelwires with similar stress-strain curves.

[0112] The examples of the present invention described above should be considered as illustrative and not as limiting the scope of the present invention as defined in the following claims. The foregoing and other objects, features, and advantages of the present invention will be apparent from the above detailed descriptions of examples of the present invention, as illustrated in the accompanying drawings wherein like reference numbers represent like parts of the present invention.

[0113] Variations in the present invention are possible in light of the description of it provided herein. 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. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.