FIELD OF THE INVENTION

[0001] The subject matter of the present invention relates to a passenger car and light truck tire that has a three layer architecture. More particularly, the present application involves a bead design that features three layers in which one of the three wraps around the bead core and the other two do not.

BACKGROUND OF THE INVENTION

[0002] Passenger car and light truck tires have a tread area that engages the road surface, and a carcass with sidewalls that extend from the tread area. The sidewalls terminate in beads that are designed to engage a rim of the wheel. The beads include a bead core made of steel and other bead tissues that can be composed of rubber. In order to improve performance of the tire it is known to lighten the weight of the bead core and sidewall, for example by reducing the number of rods of the bead core or by reducing the number of reinforcement plys in the beads and sidewalls. However, reduction in the size of the bead core causes more flexing in the tire, and the reduction of the number of reinforcement plies in the sidewall reduces the rupture strength of the sidewall.

[0003] It is known to provide tires with reinforcement plies that wrap around the bead core to increase the strength of the tire. However, this increases the mass under the bead core, and causes the bead core to be correspondingly heavier. With multiple reinforcement plies in the bead returning upwards from the bead core, engagements of these multiple reinforcements results in this area of the tire also having increased mass. Further, the reinforcement layers are generally each of two ply thickness which likewise increase the mass of the tire at this joint location. The addition of local mass in this area of the tire may cause the weight of the tire to increase and can increase rolling resistance of the tire and may decrease handling properties. As such, there is a need to reduce mass of the tire to improve rolling resistance while still maintaining the strength of the tire and improve performance properties.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: [0005] Fig. 1 is a perspective view of a tire.

[0006] Fig. 2 is a cross-sectional view of a radial cut of a tire with all items in crosssection as the tire would look when mounted to a rim in accordance with one embodiment.

[0007] Fig. 3 is a close up, cross-sectional view of a first bead of a tire as it would look when mounted to a rim in accordance with another exemplary embodiment.

[0008] Fig. 4 is a close up, cross-sectional view of a first bead of a tire as it would look when mounted to a rim in accordance with yet another exemplary embodiment.

[0009] The use of identical or similar reference numerals in different figures denotes identical or similar features.

DETAILED DESCRIPTION OF THE INVENTION

[0010] Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, and not meant as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield still a third embodiment. It is intended that the present invention include these and other modifications and variations.

[0011] The present invention provides for a tire 10 that has a three layer architecture in which first, second, and third reinforcement layers 30, 34, 38 are present. The first reinforcement layer 30 is present within the beads 24, 26 of the tire and wrap around a section of the bead cores 28, 72. The second and third reinforcement layers 34, 38 are also present within the first and second beads 24, 26, but these layers 34, 38 do not wrap around any section of the bead cores 28, 72. The three layer 30, 34, 38 increases robustness of the sidewalls 62, 64 of the tire 10, and due to their configuration within the beads 24, 26 achieve mass reduction which can improve performance of the tire 10, and may increase global endurance of the tire 10.

[0012] Fig. 1 shows a tire 10 that is a light truck tire 10. In this regard, the tire 10 is not designed for nor used with a heavy truck (payload capacity 4,000 pounds or greater) that could be found for instance on a tractor trailer, garbage truck, or box truck. The tire 10 is for use on a car, motorcycle, or light truck (payload capacity less than 4,000 pounds) As such, the tire 10 as described herein is a passenger tire or a light truck tire and is not a heavy truck tire. The tire 10 includes a casing 22 onto which a tread 20 that engages the ground or road surface is disposed. First and second beads 24, 26 are present that are part of the casing 22 that are at the inner radial end of the casing 22 closest to the central axis 12. The central axis 12 of the tire 10 extends through the center of the casing 22 and the tire 10 will rotate about this central axis 12 during operation of the tire 10. The axial direction 16 of the tire 10 is parallel to the central axis 12. The radial direction 14 of the tire 10 is perpendicular to the central axis 12 and thus is likewise perpendicular to the axial direction 16. The tread 20 is thus located farther from the central axis 12 in the radial direction 14 than the casing 22. The tread 20 extends all the way around the casing 22 in the circumferential direction 18 of the tire 10 and circles the central axis 12 360 degrees.

[0013] Fig. 2 is a radial cut of a tire 10 in accordance with one exemplary embodiment. Various tissues, sometimes called products, composed of different materials can be present throughout the tire 10. The tread 20 of the tire 10 is shown as being located farthest from the axial center of the tire 10 in the radial direction 14. A first belt layer 68 and a second belt layer 70 are in a crown 66 of the tire 10 and are located below the tread 20 in the radial direction 14 and comprise belts for use in strengthening and holding the form of the tire 10. The reinforcement belts of the layers 68, 70 may be crossed relative to one another, and in some instances they can be arranged at an angle of 20 degrees to one another. The casing 22, or carcass, extends from the tread 20 and includes sidewalls 62, 64 of the tire 10 terminating in a pair of beads 24, 26 that are arranged for mounting onto the rim of the wheel of the vehicle. A first bead core 28 is located in the first bead 24, and a second bead core 72 is within the second bead 26 and are present to provide strength and a gripping force in the beads 24, 26 for retention onto the rim of the vehicle. The left and right sidewalls 62, 64 can be mirror images of one another, and the first bead 24 can be a mirror image of the second bead 26. The sidewalls 62, 64 and beads 24, 26 can have products that are made of the same material.

[0014] Some of the tissues/products are located only in the beads 24, 26, while others are located in the beads 24, 26 and additionally extend therefrom. For instance, an inner liner 54 is inside of the first bead 24 and extends through the left sidewall 62, across the inner side of the crown 66, through the right sidewall 64, and to the second bead 26. The inner liner 54 is thus a product of the tire 10 that extends all the way from one bead 24 to the other bead 26 and is made of a material that is fluid tight so that fluid between the tire 10 and rim is maintained therein for purposes of maintaining inflation pressure of the tire 10. The inner liner 54 can have a thickness of 1.4 millimeters along the majority of the length of the inner liner 54 in the beads 24, 26. [0015] The tire 10 includes a tissue designated as a first reinforcement layer 30 that is located within the first bead 24 and extends through the sidewalls 62, 64 and crown 66 and into the second bead 26. A tissue that is designated as a second reinforcement layer 34 is in the first bead 24 and likewise extends through these parts of the tire 10 into the second bead 26. Further, an additional tissue that is the third reinforcement layer 38 is in the first bead 24 and also extends through the side walls 62, 64 and crown 66 and into the second bead 26. The layers 30, 34, 38 and 54 may be the only four layers that extend completely through the tire 10 from the first bead 24 to the second bead 26. In other embodiments, additional layers may likewise extend from bead 24 to bead 26.

[0016] A close-up view of the first bead 24 in accordance with another exemplary embodiment of the tire 10 is shown with reference to Fig. 3. The tire 10 as described is assumed to be on a rim of a vehicle so that the first bead 24 is outboard from the second bead 26 in the axial direction 16. It is to be understood that the second bead 26 can be a mirror image to the first bead 24 with the same tissues configured in the same way so a repeat of the construction of the second bead 26 is not necessary. In yet other embodiments, the second bead 26 need not be configured in the same manner as the first bead 24. The first bead core 28 may be a single piece of metal or could be made of a plurality of metal cables that are twisted relative to one another. Generally, the first bead core 28 is a metallic member, such as steel, that is harder than other tissues in the first bead 24. The first bead core 28 may have a diameter of 6.8 millimeters. Rubber tissue with a stiffness of 28 Mega pascals (Mpa) can be interspaced between these various metal rods to aid in keeping them in a desired shape. The stiffness of each metal rod in the first bead core 28 may be 30,000,000 Mega pascals and these metal rods may be made of steel or aluminum. A wrapping tissue 44 extends around the first bead core 28 and engages a section of the first bead core 28. The wrapping tissue 44 can be a textile, in some embodiments the wrapping tissue is made of Nylon, and is shown as being made of two layers, but it can be made of any number of layers in other embodiments. The wrapping tissue 44 may have a stiffness of 14 Mega pascals. The wrapping tissue 44 does not completely circle the first bead core 28 but instead leaves approximately 90 degrees of the outer surface of the first bead core 28 uncovered. The wrapping tissue 44 extends from either side of the first bead core 28 in the axial direction 16 outward in the radial direction 14. The wrapping tissue 44 may be completely contained within the first bead 24 or may be present in the first bead 24 and in some of the left sidewall 62. The wrapping tissue 44 does not extend from the first bead 24 all the way to the second bead 26 and does not go into the crown 66.

[0017] The first reinforcement layer 30 engages the inner liner 54 in the first bead 24 and wraps around a section of the first bead core 28. The first reinforcement layer 30 does not engage the first bead core 28 because the section it extends around is protected by the wrapping tissue 44 which protect the first reinforcement layer 30 from being cut by the metal first bead core 28. After wrapping around the first bead core 28, the first reinforcement layer 30 extends away from it outward in the radial direction 14, and this portion of the first reinforcement layer 30 is called a return 32. The return terminal end 33 is a terminal end of the first reinforcement layer 30 and is the portion of the return 32 that is farthest from the first bead core 28. The first reinforcement layer 30 can be a rubber or a textile and could include rubber and cords made of nylon. The first reinforcement layer 30 may have a stiffness that is from 2-5 Mpa, from 3-4 Mpa, or 3.3 Mpa in accordance with different exemplary embodiments. The first reinforcement layer 30 can have a pace of 0.81 millimeters in one embodiment which is the inclusion of one cord of the textile over every 0.81 millimeters. Since only the first reinforcement layer 30, and not the second or third reinforcement layers 34 or 38, wraps around the first bead core 28 the first bead core 28 can be made lighter and the area under the first bead core 28 which is inward in the radial direction 14 can also be made lighter. Also, since only one return 32 is present and the second and third reinforcement layers 34, 38 do not have returns there is a mass savings in this area of the first bead 24 as well.

[0018] The first bead 26 also includes a second reinforcement layer 34 that engages the first reinforcement layer 30 along a portion of the first reinforcement layer 30 that is inboard in the radial direction 14. This engagement may continue through the sidewalls 62, 64 and the crown 66 so that the second reinforcement layer 34 engages the first reinforcement layer 30 in these portions of the tire 10. The second reinforcement layer 34 also engages the wrapping tissue 44 and the inner end of the second reinforcement layer 34 in the radial direction is positioned so that it does not engage the first reinforcement layer 30 and so that the wrapping tissue 44 is between the first reinforcement layer 30 and the second reinforcement layer 34. The second reinforcement layer 34 has a second reinforcement layer terminal end 36 at the inner most point of the second reinforcement layer 34 in the radial direction 14. The second reinforcement layer 34 does not engage the first bead core 28. In other embodiments the second reinforcement layer 34 may in fact engage the first bead core 28. The second reinforcement layer terminal end 36 may be outward of the entire first bead core 28 in the radial direction 14 so that no portion of the second reinforcement layer 34 is at the same point or inward of any portion of the first bead core 28 in the radial direction 14. The second reinforcement layer 34 can be a rubber or a textile and could include rubber and cords made of nylon. The second reinforcement layer 34 may have a stiffness that is from 2-5 Mpa, from 3-4 Mpa, or 3.3 Mpa in accordance with different exemplary embodiments. The second reinforcement layer 34 can have a pace of 0.81 millimeters in one embodiment which is the inclusion of one cord of the textile over every 0.81 millimeters. The second reinforcement layer 34 may be the same material with the same properties as the first reinforcement layer 30.

[0019] The tire 10 includes a third reinforcement layer 38 that is in the first bead 24 and extends through the sidewalls 62, 64 and crown 66 and into the second bead 26. The third reinforcement layer 38 engages the second reinforcement layer 34 in the crown 66 and in the sidewalls 62, 64, but is free from engagement with the second reinforcement layer 34 in the first and second beads 24, 26. The third reinforcement layer 38 engages the return 32 in the first bead 24, and is free from engagement with the wrapping tissue 44 and the first bead core 28. A third reinforcement layer terminal end 40 is at the end of the third reinforcement layer 38 and is the inward most point of the third reinforcement layer 38 in the radial direction 14. The third reinforcement layer terminal end 40 is positioned so that it is inward from some portions of the first bead core 28 in the radial direction 14, but also so that it is outward from other portions of the first bead core 28 in the radial direction 14. The entire third reinforcement layer 38 in the first bead 24 is located outboard in the axial direction 16 from the entire first bead core 28. The third reinforcement layer 38 does not wrap around the first bead core 28 such that the third reinforcement layer 38 does not extend around the first bead core 28 so as to be both inboard and outboard in the axial direction 16 from the first bead core 28.

[0020] The third reinforcement layer 38 can be a rubber or a textile and could include rubber and cords made of nylon. The third reinforcement layer 38 may have a stiffness that is from 10-15 Mpa, from 12-13 Mpa, or 12.5 Mpa in accordance with different exemplary embodiments. The third reinforcement layer 38 can have a higher stiffness than the first reinforcement layer 30, and the third reinforcement layer 38 can have a higher stiffness than the second reinforcement layer 34. The first and second reinforcement layers 30, 34 can have a stiffness that is the same as one another. The third reinforcement layer 38 can have a pace of 0.81 millimeters in one embodiment which is the inclusion of one cord of the textile over every 0.81 millimeters. The third reinforcement layer 38 may have different properties than both the first and second reinforcement layers 30, 34. The third reinforcement layer 38 can have a higher stiffness than the first reinforcement layer 30 and can have a higher stiffness than the second reinforcement layer 34.

[0021] The third reinforcement layer 38 does not have a return, and its configuration along with those of the first and second reinforcement layers 30, 34 result in four layers (two for the first reinforcement layer 30, one for the second reinforcement layer 34, and one for the third reinforcement layer 38) radially outward from the first bead core 28. Presence of four layers as opposed to five or six in this area allows for a lighter first bead 24 and possible reduction in the thickness of the first bead 24 at this location. The reinforcement layers 30, 34, 38 may be radials with each joint adding locally a two-ply thickness. The inclusion of a single return 32 in the three ply 30, 34, 38 design may reduce local heterogeneities in this area because the same number of plies will be located on opposite axial direction 16 sides of the first bead core 28 in the area above the first bead core 28 in the radial direction 14.

[0022] The first bead core 28 has a lower point 42 that is the inner most point of the first bead core 28 in the radial direction 14. Various distances can be established between the lower point 42 and the reinforcement layers 30, 34 and 38 to establish the positional relationships between various tissues in the first bead 24. A distance 56 is noted as being between the lower point 42 and the return terminal end 33 and extends directly from the lower point 42 to the return terminal end 33 so as to have components of extension in both the radial direction 14 and the axial direction 16. The distance 56 can be from 30-60 millimeters, from 35-55 millimeters, from 40-50 millimeters, or from 42-47 millimeters in various embodiments. In one exemplary embodiment, the distance 56 is 45 millimeters.

[0023] The radial distance 60 is the distance in the radial direction 14 from the lower point 42 to the second reinforcement layer terminal end 36. This radial distance 60 is only the component of distance that extends in the radial direction 14, and radial distance 60 does not include any component of distance in the axial direction 16. A line that extends in the axial direction 16 is drawn through the lower point 42, and the distance in the radial direction 14 from this line to the second reinforcement layer terminal end 36 is measured to result in the radial distance 60. The radial distance 60 can be from 4-10 millimeters, from 5-9 millimeters, from 2-12 millimeters, or from 6-8 millimeters in accordance with various exemplary embodiments. In one exemplary embodiment, the distance 60 is 7 millimeters. In some embodiments the radial distance 60 is set so that some portion of the first bead core 28, but not all of the bead core 28, is outward of the second reinforcement layer terminal end 36 in the radial direction 14.

[0024] The radial distance 58 is the radial distance from the lower point 42 to the third reinforcement layer terminal end 40. The radial direction 58 is only the component of distance that extends in the radial direction 14 and does not include any component of distance extension in the axial direction 16. A line that extends in the axial direction 16 is drawn through the lower point 42, and the distance in the radial direction 14 from this line to the third reinforcement layer terminal end 40 is measured to result in the radial distance 58. The radial distance 58 can be 0 millimeters, 1 millimeter, 2 millimeters, or 3 millimeters in accordance with different exemplary embodiments. In some embodiments, the third reinforcement layer terminal end 40 can extend inward in the radial direction 14 to such a point that it is below the lower point 42. In these instances, the radial distance 58 can be a “negative” number such as being -1 millimeter, -2 millimeters, from -3 to -5 millimeters, - 6 millimeters, or from -3 millimeters to +7 millimeters.

[0025] The first bead 24 includes a tissue that is a bead filler 46 that functions to separate the second reinforcement layer 34 from the return 32. The bead filler 46 engages the first bead core 28, the wrapping tissue 44, the return 32, and the second reinforcement layer 34 in the first bead 24. The bead filler 46 extends from the first bead 24 into the left sidewall 62 but does not extend to the crown 66. In the left sidewall 62, the bead filler 46 engages the third reinforcement layer 38. The bead filler 46 can have a stiffness from 5-10 MPa, from 6-9 MPa, from 7-8 MPa, or 7.4 MPa. The value of the stiffness of the bead filler 46 may be between that of the first reinforcement layer 30 and the third reinforcement layer 38.

[0026] Additional tissue layers can be found within the first bead 24 as shown in Fig. 3. A first bead layer 50 is present and located completely outboard in the radial direction 14 from the first bead core 28. The first bead layer 50 engages the third reinforcement layer 38 but is free from engagement with both the first reinforcement layer 30 and the second reinforcement layer 34. The first bead layer 50 is located on the outboard side of the third reinforcement layer 38 in the radial direction 14. The first bead layer 50 may be located only within the first bead 24 or can be located within the first bead 24 and also extend so as to be located within the left sidewall 62. The first bead layer 50 does not extend to the crown 66. The first bead layer 50 can have a stiffness from 5-10 MPa, from 6-9 MPa, from 7-8 MPa, or 7.4 MPa. The value of the stiffness of the first bead layer 50 may be between that of the first reinforcement layer 30 and the third reinforcement layer 38.

[0027] A second bead layer 52 is present within the first bead 24 and does not extend to the left sidewall 62. The second bead layer 52 engages the first reinforcement layer 30 and the inner liner 54 but is free from engagement with the second reinforcement layer 34 and the third reinforcement layer 38. The second bead layer 52 forms a small portion of the outer surface of the first bead 24.

[0028] An anti-abrasive strip 48 is also located within the first bead 24 and engages the second bead layer 52, the first reinforcement layer 30, and the first bead layer 50. The anti-abrasive strip 48 is free from engagement with the second reinforcement layer 34, the first bead core 28, the wrapping tissue 44, and the bead filler 46. The anti-abrasive strip 48 can be located only within the first bead 24 or can be located within the first bead 24 and extend into the left sidewall 62 but not into the crown 66. The anti-abrasive strip 48 forms a portion of the exterior surface of the first bead 24 and engages the rim when the tire 10 is mounted.

[0029] The tire 10 can also include a sidewall product 74 that forms a portion of the sidewall 62. The sidewall product 74 may extend into the first bead 24 so as to form a portion of the first bead 24, or the sidewall product 74 may not be within the first bead 24 but only within the left sidewall 62. The sidewall product 74 can have a thickness of 5 millimeters near the first bead 24 and can be thicker in areas closer to the shoulder of the tire 10 such that it is 10 millimeters thick near the tread 20. The sidewall product 74 engages the third reinforcement layer 38, the anti-abrasive strip 48, and the first bead layer 50 and forms the exterior portion of the sidewall of the tire 10. The sidewall product 74 does not engage the first or second reinforcement layers 30, 34, and does not engage the first bead core 28. The sidewall product 74 has a thickness 76 that extends completely in the axial direction 16 from the exterior sidewall of the casing 22 to the third reinforcement layer 38. The thickness 76 may be 5 millimeters in some embodiments, 3 millimeters in other embodiments, and from 3-6 millimeters in yet additional embodiments.

[0030] An alternative exemplary embodiment of the tire 10 is shown in Fig. 4 which shows an enlarged view of the first bead 24. The first, second and third reinforcement layers 30, 34 and 38 are again provided so that they extend from the first bead 24 to the second bead 26, and so that the first reinforcement layer 30 wraps around the first bead core 28 but the second and third reinforcement layers do not wrap around the first bead core 28. The wrapping tissue 44 is not present, and the first reinforcement layer 30 wraps around and in fact engages the first bead core 28. The distances 56, 58, 60 can be the same as previously discussed. However, the radial distance 60 is greater in this embodiment as the second reinforcement layer terminal end 36 is spaced completely outward from the first bead core 28 in the radial direction 14 so that no portion of the bead core 28 is at the same radial location as the second reinforcement layer terminal end 36. The first and second bead layers 50 and 52 are not present in this embodiment, and the bead filler 46 engages the first reinforcement layer 30 both at the return 32 and at a portion of the first reinforcement layer 30 that is inboard in the axial direction 16 from the first bead core 28. [0031] The three ply architecture which includes the first, second, and third reinforcement layers 30, 34, 38 imparts robustness to the tire 10. The three plys 30, 34, 38 globally increase the rupture force of the sidewalls 62, 64 about 36% versus a similar design having but two of the plys 30, 34 or 38. The shorter distance 56, which can be 45 millimeters or less in some embodiments, allows for easier manufacturing of the design on an industrial scale. The geometry of the provided three ply architecture also allows for a reduction in the mass of the tire 10. The inclusion of a single return 32 instead of two or more returns is easier and better for conception.

[0032] The casing 22 has a second bead 26 that has the second bead core 72. The second bead 26, including the second bead core 72, can be arranged in a similar manner as that of the first bead 24 and the first bead core 28 and a repeat of this information is not necessary. The various tissues, arrangements, dimensions, and variations described with respect to the first bead 24 are applicable to the second bead 26 and the second bead 26 can be provided in any of the manners as described with respect to the first bead 24. The second bead 26 can thus be the same as the first bead 24, or in some arrangements differences can exist so that they are different.

[0033] The present application describes the stiffness of a product or material. The stiffness that is being referred to is the Young’s modulus which is the stiffness of an elastic material, or elastic modulus. The stiffness is provided in measurements of mega pascals (MPa). The stiffness material property in question that is being referred to is MAIO. This stiffness property can be calculated using French standard NF T 46-002, September 1988. The various tissues and layers described in the casing 22 can all be made of rubber, metals, textiles, combinations of these materials, in addition to other components to yield desired properties for these component layers and parts.

[0034] While the present subject matter has been described in detail with respect to specific embodiments and methods thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, the scope of the present disclosure is by way of example rather than by way of limitation, and the subject disclosure does not preclude inclusion of such modifications, variations and/or additions to the present subject matter as would be apparent.