WO2019108208A1

WO2019108208A1 - Pneumatic tire

Info

Publication number: WO2019108208A1
Application number: PCT/US2017/064014
Authority: WO
Inventors: Jeff HIDDE; Mary Dungan THOMAS; Paul B. Winston; Vittoria Madonna BLASUCCI; Donald Earl LEONARD; Michael Andrews
Original assignee: Compagnie Generale Des Etablissements Michelin
Priority date: 2017-11-30
Filing date: 2017-11-30
Publication date: 2019-06-06

Abstract

A pneumatic tire having a pair of annular bead areas (12), a pair of sidewalls, and a crown portion wherein a carcass ply (22) wraps around a radial inner side (RSj,2o ) of each bead ring (20), for each bead area (12) a first layer of rubber material (30) is arranged radially inward from both the bead ring radial inner side (RSj,2o ) and the carcass ply (22) and a second layer of rubber material (40) is arranged radially inward from the first layer of rubber material (30), each of the first layer of rubber material (30) and the second layer of rubber material (40) extending substantially across a full width (W20 ) of the corresponding bead ring (20), each of the first and second layer of rubber material (30, 40) having a modulus of elongation, where the modulus of elongation of the first layer of rubber material (30) is greater than the modulus of elongation of the second layer of rubber material (40).

Description

PNEUMATIC TIRE

Field

[0001] Embodiments of this disclosure relate generally to pneumatic tires, and more specifically to tubeless pneumatic tires.

BACKGROUND

[0002] The invention concerns the structures and production of tubeless tires having rim mounting and sealing portions each characterized as having improved resistance to rim mounting damage.

[0003] Tubeless pneumatic tires having one or more carcass plies extending between a pair of substantially unstretchable bead rings (which may be more simply referred to herein as “beads”), one or more carcass plies being surmounted by a crown reinforcement and a tread, the one or more carcass plies being partially wound at each of their two ends around each of the bead rings. A crown reinforcement may also be referred to also as a belt or belt package. Each of the one or more carcass plies and crown reinforcement being reinforced with cables or cords within a rubber matrix.

[0004] In the case of tubeless tires, it is necessary that the pressurized inflation atmosphere not be lost by diffusion into the materials of the mounted assembly or by leaks caused by an inadequate seal between tire and rim. Additionally, the structure forming the seal together with the surrounding portions near each bead ring must withstand mounting forces observed when mounting the tire on a rim or dismounting the tire from rim.

[0005] Presently, there is a desire to improve the ability of the sealing portion of the tire, or more specifically, the portion of the tire arranged between each bead ring and the radially inner rim-seating portion of the tire as is arranged within a bead area of the tire, to provide sealing capabilities while also better resisting the occurrence of damage during that may occur during tire mounting or tire dismounting.

SUMMARY

[0006] Embodiments of this disclosure include various pneumatic tires, which may be tubeless, the tires having: a pair of annular beads areas spaced apart axially along a rotational axis of the tire; a pair of sidewalls spaced apart axially along the rotational axis of the tire, each sidewall of the pair of sidewalls extending outwardly in a radial direction from one bead area of the pair of bead areas; and, a crown portion arranged between the pair of sidewalls. For each bead of the pair of bead areas, a carcass ply wraps around a radial inner side of a bead ring such that the carcass ply extends along an axial outer side of the bead ring, across a radial inner side of the bead ring, and an axial inner side of the bead ring, the carcass ply comprising an array of reinforcements arranged within a matrix of elastomeric material. In particular embodiments, for each bead area of the pair of bead areas, a first layer of rubber material is arranged radially inward from both the bead ring radial inner side and the carcass ply. Further, for each bead area of the pair of bead areas, a second layer of rubber material is arranged radially inward from each of the bead ring radial inner side, the carcass ply, and the first layer of rubber material, each of the first layer of rubber material and the second layer of rubber extending substantially across a partial or full width of the corresponding bead ring. Each of the first layer of rubber material and the second layer of rubber material having a modulus of elongation, where the modulus of elongation of the first layer of rubber material is greater than the modulus of elongation of the second layer of rubber material.

[0007] The foregoing and other objects, features, and advantages will be apparent from the following more detailed descriptions of particular embodiments, as illustrated in the accompanying drawings wherein like reference numbers represent like parts of particular embodiments.

DETAILED DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a perspective view of a tubeless pneumatic tire, in accordance with an exemplary embodiment;

[0009] FIG. 2 is a perspective view of a bead portion located at the radially inner end of a sidewall, in accordance with an exemplary embodiment; and,

[0010] FIG. 3 is a perspective view of a bead portion located at the radially inner end of a sidewall, in accordance with the prior art.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

[0011] The following terms are defined as follows for this disclosure: [0012]“Rubber” or “rubber material” as used herein, alone and without modification, indicates any natural rubber (polyisoprene), synthetic rubber, or any blend thereof. Synthetic rubbers include, by example and without limitation, butadiene rubbers (BR), styrene- butadiene rubbers (SBR), isoprene, chloroprene, and isobutylene.

[0013]“Axial direction,”“axially,” or the letter“A_d” in the figures refers to a direction extending along the axis of rotation or a direction parallel to the axis of rotation of, for example, the outer band, the inner hub, or more generally, the non-pneumatic tire carcass.

[0014]“Radial direction,”“radially,” or the letter“R_d” in the figures refers to a direction that is orthogonal to the axis of rotation and extends in the same direction as any radius extending orthogonally from the rotational axis.

[0015]“Circumferential direction” or the letter“C_d” in the figures refers to a direction is orthogonal to an axial direction and orthogonal to a radial direction.

[0016]“Elastic material” or“elastomer” as used herein refers to a polymer exhibiting rubber like elasticity, such as a material comprising rubber, whether natural, synthetic, or a blend of both natural and synthetic rubbers.

[0017]“Elastomeric” as used herein refers to a material comprising an elastic material or elastomer, such as a material comprising rubber.

[0018]“Modulus” or“Modulus of elongation” (MPa) was measured at 10% strain (MA10) at a temperature of 23°C based on ASTM Standard D412 on dumb bell test pieces. The measurements were taken in the second elongation; i.e., after an accommodation cycle. These measurements are secant moduli in MPa, based on the original cross section of the test piece.

[0019] With reference to an exemplary tubeless pneumatic tire 10 in FIG. 1, tire 10 includes a pair of annular bead areas 12. Internally within each bead area 12 various components are arranged, including a bead ring (not shown, but shown in FIGS. 2 and 3). Each bead ring 12 is also referred to as a bead herein. Each bead ring is substantially unstretchable under the normal loading conditions observed during intended tire installation and operation, and it is appreciated that each bead ring may comprise any desired bead ring. The pair of bead areas 12, as well as the pair of beads arranged therein, are spaced apart axially along a rotational axis A of the tire 10. Each bead area includes a rim sealing portion 14 arranged between each bead and a radial inner side RSyo of tire 10 within bead area 12, each of the rim sealing portion 14 and radial inner side RSyo extending circumferentially (in a circumferential direction C_d) around the tire 10.

[0020] With continued reference to FIG. 1, tire 10 also includes a pair of sidewalls 16 spaced apart axially along the rotational axis A of tire 10. Each sidewall 16 extends outwardly in a radial direction R from one bead area 12. Tire 10 also includes a crown portion 18 arranged between the pair of sidewalls 16. In the embodiment shown, the crown portion 18 includes a tread 19 arranged along a radially outer side of the crown portion to form an outer, ground- engaging side of the tire 10. Tread 19 is employed to create traction during tire operation.

[0021] With reference now to FIG. 2, showing one of the bead areas 12 of the tire 10 shown in FIG. 1, the bead area 12 being constructed in accordance with one variation of various variations contemplated herein. In the variation shown, each bead area 12 includes a carcass ply 22 that wraps around a radial inner side RSyo of a bead ring 20 such that the carcass ply 22 extends along an axial outer side AS₀,2o of the bead ring 20, across the radial inner side RSi,₂₀ of the bead ring 20 (which is also referred to as a bottom side of the bead ring), and an axial inner side AS,, 20 of the bead ring 20. In extending along the axial outer side AS₀,2o and/or the axial inner side AS,, 20, in certain variations the carcass ply 22 may continue extending radially outward and into a corresponding sidewall 16. It is appreciated that the carcass ply may generally extend radially across the crown portion 18 and to each bead ring 20, whether the carcass ply is a continuous ply or is formed of multiple, connected portions. As appreciated by one of ordinary skill, carcass ply 22 comprises an array of reinforcements arranged within a matrix of elastomeric material (not shown). For example, such reinforcements may comprise elongate cables or cords.

[0022] Bead ring 20 is optionally surrounded by a rubber stiffener 21_R and an outer wrap 21w- Bead ring 20 is configured to remain rigid annularly (that is, in a hoop direction) and comprises one or more rigid reinforcements, such one or more metal reinforcements, for example. Generally, it is appreciated that bead ring 20 may comprise any desired bead known to one of ordinary skill. In this exemplary embodiment, rubber stiffener 21_R is arranged around bead 21, both in an annular direction and around the bead ring cross-section taken along a plane extending in both radial and axial directions. Rubber stiffener 21_R is a rigid rubber formulation designed to increase the rigidity of bead ring 20. A wrap 21w is arranged around rubber stiffener 21_R to contain the rubber stiffener 21_R. Wrap 21w may consist of a rubber material that may or may not include reinforcements, such as any elongate textile or metal reinforcements, for example.

[0023] With continued reference to FIG. 2, each bead area 12 includes a first layer of rubber material 30 arranged radially inward from both the bead ring radial inner side RSyo and the carcass ply 22. Each bead area 12 also includes a second layer of rubber material 40 arranged radially inward from each of the bead ring radial inner side RSi,2o, the carcass ply 22, and the first layer of rubber material 30. It is appreciated that the first layer of rubber material 30 has a thickness t₃₀ and the second layer of rubber material 40 has a thickness t₄₀. At least below the radial inner side RS^o of the bead ring 20, the first layer thickness t₃₀ is at least substantially 1 millimeter (mm) and upwards of substantially 50% of the combined thickness (t₃o + t-io) of the first layer of rubber material 30 and the second layer of rubber material 40 or substantially 50% of a distance extending in the direction of each layer thickness t₃o, t₄o between the carcass 22 and the inner radial side S o of tire 10 . At least below the radial inner side RS^o of the bead ring 20, the second layer thickness t₄o is at least substantially 1 millimeter (mm) and as great as a thickness that fills the distance remaining between the carcass 22 and the inner radial side S o of tire 10 when the first layer 30 is at a minimum thickness t₃o (e.g., 1 mm). For the purpose of clarity, the portion of each first and second layer of rubber material 30, 40 arranged below a bead ring 20 is the portion extending partially across or substantially the full width W20 or W20’ of the bead ring 20. Accordingly, it is appreciated that the thickness t₃o, t₄o of other portions of each layer 30, 40 may be greater or less than the minimums and maximums described above.

[0024] Each of the first and second layers of rubber material 30, 40 are formed of different rubber material having different rigidities, that is, having different flexibility qualities. In particular, the first layer of rubber material 30 is more rigid (that is, less flexible) than the second layer of rubber material 40. In these instances, by providing a less flexible first layer of rubber material 30, one that is less flexible than the second layer of rubber 40, the increased rigidity of the first layer of rubber material 30 reinforces the carcass ply 22, with the first layer of rubber material being arranged adjacent to the carcass ply 22 (as is more fully described below). Accordingly, damage to the carcass ply is reduced due to the additional reinforcement. In certain instances where the first layer of rubber 30 is more rigid than the second layer of rubber 40, where the modulus of elongation of the first layer of rubber material 30 is greater than the modulus of elongation of the second layer of rubber material 40. In particular variations, the modulus of elongation of the first layer of rubber material 30 is equal to at least 125%, is equal to 125% to 250%, or is equal to 150% to 200% of the modulus of elongation of the second layer of rubber material 40. In certain instances, it can be said that the first layer of rubber material 30 has a modulus of elongation that is substantially equal to or greater than, that is, not less than, the modulus of elongation of the rubber material forming the carcass ply 22. In one example, the modulus of elongate of the rubber material forming the carcass ply 22 is 10 MPa, although it could be a value greater or less than 10 MPa in other variations. Further, in certain exemplary instances, the modulus of elongation for the first layer of rubber material 30 is as great as substantially 14 MPa (and therefore ranging from 10 to 14 MPa in certain more particular exemplary instances), while the modulus of elongation for the second layer of rubber material 40 is substantially 7.5 MPa, or more generally 6 MPa to 8 MPa.

[0025] It is understood that the first and second layers of rubber material 30, 40 may be each be formed of any desired rubber to achieve the rigidity or elongation properties described herein. Rubber may comprise natural rubber, synthetic rubber, or any rubber blend as noted previously. It is further appreciated that synthetic rubber may include any additives to achieve the material properties desired. It is appreciated that each of the first and second layers of rubber material 30, 40 are formed substantially or completely of rubber material, such that each does include any reinforcements, such as, for example and without limitation, any elongate cables or cords.

[0026] With reference again to FIG. 2, additional details regarding each bead area 12 are provided. It is appreciated that radial inner side S o of tire 10 within bead portion 12 forms a rim sealing portion 14, which generally extends linearly in cross-section between a first transition T1 and to a second transition T2, where at the first transition T1 sealing portion transitions to an exterior side 10S_e of the tire and where at the second transition T2 sealing portion transitions to an interior side lOS, of the tire 10, the exterior side 10S_e of the tire being located axially outward from the inner side of the tire. First transition T1 is referred to as a heel and the second transition T2 is referred to as a toe. It is noted that“rim sealing portion” is used interchangeably with“radial inner side” with regard to this embodiment. Line L_RIM is a reference line representing a portion of a rim upon which the rim sealing portion 14 is intended to engage when tire 10 is properly mounted on a rim. In particular embodiments, the angularity of line L_RIM is biased from rim sealing portion RSyo by angle Q as measured from an origin located along the rim sealing portion RS o at the first transition T1 in a direction such that the line L_RIM extends towards the interior side lOS, of the tire between the second transition T2 and the bead ring 20. In particular embodiments, angle Q is substantially 15 degrees while in broader instances, angle Q is substantially in the range of 0 to 15 degrees. As measured in a direction parallel to line L_RIM, bead ring 20 has a width W20. In the embodiment shown, first layer of rubber material 30 extends substantially across the full bead width W20. In lieu of measuring the bead ring width W20 in a direction parallel to a reference rim line LRIM, the width of the bead ring 20 can be measured in an axial direction of the tire 10, with the tire in a molded or unmounted configuration. This alternative measurement of the bed ring width is represented by W2o’· In other variations, first layer 30 extends partially or at least 50% across width W20, W2o’· Likewise, second layer 40 may extend partially, at least 50%, or substantially across width W20, W2o’· With reference to FIG. 3, this this arrangement of a first layer 30 extending substantially across a full width of the bead ring 20 is contrary to prior art bead areas 112, where no first layer of rubber material is arranged below the bead ring 20 let alone extending substantially across the full bead width W20. Instead, an outer shear layer 80 is arranged along an axially outer side of the bead area 112 between a portion of second layer of rubber material 140 and reinforcement, where the outer shear layer 80 is flexible for the purpose of reducing strain densities along reinforcement ply 60. In certain embodiments, the outer shear layer 80 has a modulus of elongation generally ranging from 3 to 6 MPa in certain embodiments. Therefore, second layer of rubber material 140 is the only rubber material arranged between carcass ply 22 and the rim sealing portion.

[0027] In addition to extending substantially across the full bead width W20, it is appreciated that first layer of rubber material 30 may extend further toward the interior side lOS, of the tire. For example, first layer of rubber material 30 continues to an inner terminal end 30E, located beyond a line LRAD extend in a radial direction from a radially inner and axially inner corner of the bead 20. More specifically, first layer of rubber material 30 extends to an inner terminal end 30E, that is overlapped by an outer terminal end 50E_o of an inner liner ply 50, the inner liner ply 50 being an air impermeable layer of material that prevents the leakage of air through the tire between the seals formed along each pair of bead areas 12. Optionally, in the example shown, the first layer of rubber material 30 is also overlapped by a second liner ply 52, which is formed of rubber material configured to react with oxygen to thereby prevent migration of oxygen. The second liner ply 52 is arranged between the inner liner ply 50 and the carcass ply 22. In other variations, for example, inner terminal end 30E, overlaps outer terminal end 50E_o of inner liner ply 50, the inner liner ply 50 being an air impermeable layer of material that prevents the leakage of air through the tire between the seals formed along each pair of bead areas 12. Optionally, in the example shown, the first layer of rubber material 30 is also overlapped by a second liner ply 52, Regardless, in other variations, it is appreciated that first layer of rubber material 30 may or may not terminate at an inner terminal end 30Ei prior to reaching an inner axial side AS,, 20 of the bead 20 or a corresponding sidewall 16.

[0028] In addition to extending substantially across the full bead width W₂o, and in any variation concerning the location at which inner terminal end 30Ei, first layer of rubber material 30 may also extend further towards the exterior side 10S_e of the tire, whereby outer terminal end 30E_o is arranged at any location from the radial inner side RSi,₂o to the axial outer side AS₀,₂o and beyond to a corresponding sidewall 16. In the present example, however, the first layer of rubber material 30 terminates at an outer terminal end 30E_o located substantially at the axially outer extent of the bead width W₂o. More generally, outer terminal end 30E_o of first layer 30 is located prior to reaching a reinforcement ply 60 located along an outer axial side AS₀,₂o of the bead 20, the reinforcement ply 60 extending radially outward towards a corresponding sidewall 16 to terminate at a location within the bead area 12 below a radial terminal end of a rubber filler 70. Reinforcement ply 60 is a rubber matrix containing an array of elongate reinforcements, such as metal reinforcements, for example, but in other variations may comprise any desired reinforcement ply. Also, in the present example, the reinforcement ply 60 is arranged between the first layer of rubber material 30 and bead 20, and extends from an outer axial side AS₀,₂o of the bead 20 and radially outward to terminate at a location within the bead area 12 below a radial terminal end 70E_o of a rubber filler 70. Rubber filler 70 is a rigid rubber material arranged along a radial outer side RS₀,₂o and extends radially outward to a terminal end within the bead area 12, where a thickness of the rubber filler 70 narrows as the rubber filler extends radially outward to its radial outer terminal end 70E_o. In particular embodiments, such as is shown, rubber filler 70 is characterized as having a triangular cross-section shape in a plane extending radially and axially.

[0029] With continued reference to FIG. 2, in addition to extending substantially across the full bead width W₂o, it is appreciated that second layer of rubber material 40 may extend further toward the interior and/or exterior sides lOS,, 10S_e of the tire. In the example shown, the second layer of rubber material 40 within each bead area 12 extends from an exterior side 10S_e of the tire to an interior side lOS, of the tire. It is further noted that in the example shown, the second layer of rubber material 40 is arranged to form an exterior surface of the tire, although in other variations, second layer may remain internal (at least partially) with one or more additional layers of material arranged external to the second layer.

[0030] By virtue of employing the first and second layers of rubber material 30, 40 as described herein, improved resistance to mounting and dismounting damage is achieved by virtue of the more rigid first (inner) layer 30 better protecting the carcass ply 22 by isolating the carcass ply 22 from the mounting and dismounting forces observed by the second (outer) layer 40. It is noted that the bead area construction shown in FIGS. 2-4 represent bead area constructions employed by any over-the-road or off-road truck tires, as there is a greater propensity for experience bead- area damage due to the more frequent mounting and dismounting of tires, which are often retreaded and returned to service. Still, utilization of the inner and outer layers of rubber material 30, 40 as described and contemplated herein may be employed by other pneumatic tires, such as passenger car tires, light truck tires, high performance tires, and motorcycle tires, for example.

[0031] To the extent used, the terms “comprising,” “including,” and “having,” or any variation thereof, as used in the claims and/or specification herein, shall be considered as indicating an open group that may include other elements not specified. The terms“a,”“an,” and the singular forms of words shall be taken to include the plural form of the same words, such that the terms mean that one or more of something is provided. The terms“at least one” and“one or more” are used interchangeably. The term“single” shall be used to indicate that one and only one of something is intended. Similarly, other specific integer values, such as “two,” are used when a specific number of things is intended. The terms“preferably,” “preferred,”“prefer,”“optionally,”“may,” and similar terms are used to indicate that an item, condition or step being referred to is an optional (i.e., not required) feature of the embodiments. Ranges that are described as being“between a and b” are inclusive of the values for“a” and“b” unless otherwise specified.

[0032] While various improvements have been described herein with reference to particular embodiments thereof, it shall be understood that such description is by way of illustration only and should not be construed as limiting the scope of any claimed invention. Accordingly, the scope and content of any claimed invention is to be defined only by the terms of the following claims, in the present form or as amended during prosecution or pursued in any continuation application. Furthermore, it is understood that the features of any specific embodiment discussed herein may be combined with one or more features of any one or more embodiments otherwise discussed or contemplated herein unless otherwise stated.

Claims

CLAIMS What is claimed is:

1. A pneumatic tire comprising:

a pair of annular beads areas spaced apart axially along a rotational axis of the tire;

a pair of sidewalls spaced apart axially along the rotational axis of the tire, each sidewall of the pair of sidewalls extending outwardly in a radial direction from one bead area of the pair of bead areas; and,

a crown portion arranged between the pair of sidewalls;

where for each bead of the pair of bead areas, a carcass ply wraps around a radial inner side of a bead ring such that the carcass play extends along an axial outer side of the bead ring, across a radial inner side of the bead ring, and an axial inner side of the bead ring, the carcass ply comprising an array of reinforcements arranged within a matrix of elastomeric material,

where for each bead area of the pair of bead areas, a first layer of rubber material is arranged radially inward from both the bead ring radial inner side and the carcass ply, the first layer of rubber material extending substantially across a width of the corresponding bead ring,

where for each bead area of the pair of bead areas, a second layer of rubber material is arranged radially inward from each of the bead ring radial inner side, the carcass ply, and the first layer of rubber material, each of the first layer of rubber material and the second layer of rubber material extending substantially across a width of the corresponding bead ring,

each of the first layer of rubber material and the second layer of rubber material having a modulus of elongation, where the modulus of elongation of the first layer of rubber material is greater than the modulus of elongation of the second layer of rubber material.

2. The pneumatic tire of claim 1, where the modulus of elongation of the first layer of rubber material is equal to 125% to 250% of the modulus of elongation of the second layer of rubber material.

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3. The pneumatic tire of claim 2, where the modulus of elongation of the first layer of rubber material at least equal to substantially 150% to 200% of the modulus of elongation of the second layer of rubber material.

4. The pneumatic tire of any one of claims 1 to 3, where the modulus of elongation for the first layer of rubber is 10 to 14 MPa and the modulus of elongation for the second layer of rubber is 6 to 8 MPa.

5. The pneumatic tire of any one of claims 1 to 4, where the modulus of elongation of the first layer of rubber material is substantially equal to or greater than a modulus of elongation of a rubber material forming the carcass ply.

6. The pneumatic tire of any one of claims 1 to 5, where an outer terminal end of the first layer of rubber material term in ales substantially at an axially outer extend of the bead ring width.

7. The pneumatic tire of any one of claims 1 to 5, where the first layer of rubber material terminates at a location radially inward from the bead ring.

8. The pneumatic tire of any one of claims 1 to 7, where an inner terminal end of the first layer of rubber material extends further towards an inner side of the tire from the bead ring width where the first layer of rubber material engages or overlaps an inner liner ply.

9. The pneumatic tire of any one of claims 1 to 7, where the first layer of rubber material extends further towards an inner side of the tire from the bead ring width and is overlapped by an inner liner ply, the inner liner ply being an air-impermeable membrane.

10. The pneumatic tire of any one of claims 1 to 9, where the second layer extends from an outer side of the tire to an inner side of the tire.

11. The pneumatic tire of any one of claims 1 to 10, where the second layer of rubber material is arranged to form an exterior surface of the tire.

12. The pneumatic tire of any one of claims 1 to 11, where the full width of the bead ring extends in a direction parallel to a reference line, the reference line biased towards the bead ring by 0 to 15 degrees from a rim sealing portion of the bead area arranged along a radial inner side of the bead area.

13. The pneumatic tire of any one of claims 1 to 11, where the full width of the bead ring extends in an axial direction of the tire.