Pneumatic tire

Abstract

To provide a pneumatic tire having a tire cavity with one or more sound dampening elements attached to a sealant material layer.SOLUTION: A pneumatic tire comprises a sealant material layer 30 covering an inner surface radially below a tread portion 10 within a tire cavity 6, and at least one noise dampening strip such as a foam strip 20 which is partially covering and attached to the sealant material on a radially inner side of the sealant material layer 30. The sealant material layer has at least one plateau region 40 supporting the noise dampening element, and one or more bottom regions 50 provided laterally beside the plateau region 40, where the plateau region 40 extends out of the bottom regions 50 in a radially inner direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a pneumatic tire provided with a puncture seal, and more particularly to a tubeless pneumatic rubber tire having a puncture seal feature. The present invention particularly relates to a pneumatic tire, especially a pneumatic tire having a sealing layer carrying at least one noise damping element on its inner surface.

Background Art

[0002] Self-sealing pneumatic tires typically slow down or prevent air pressure loss and the resulting tire shrinkage after the tire is punctured by a sharp object such as a nail or screw. For puncture-sealing pneumatic tires, a plurality of methods, seals and tire structures have been proposed. However, most of these approaches have drawbacks.

Summary of the Invention

Problems to be Solved by the Invention

[0003] In the prior art, in order to reduce the noise generated by the tire during driving, particularly the noise resulting from the cavity resonance of the tire, it is known to provide noise damping elements on the sealing material. Unfortunately, attaching the noise damping elements to the sealing material can adversely affect the sealing performance of the sealing material due to the interaction with the damping elements that can inhibit the sealing material from functioning as a seal in the case of a tire puncture. Furthermore, providing a sealing material and / or a foaming material on the inner liner of the tire may cause heat generation in the areas covered with the sealing material and / or the damping material as compared to a tire that does not contain such materials. Therefore, it is desirable to provide an improved tire that has low noise generation due to tire cavity resonance, good sealing performance and / or limited heat generation properties.

[0004] A first object of the present invention is to provide an advanced pneumatic tire having a tire cavity with one or more sound damping elements attached to a layer of sealing material.

[0005] Another object of the present invention is to provide an advanced pneumatic tire having one or more sound deadening elements and a sealing layer, particularly above the sealing layer in the radial direction, with good sealing characteristics and / or limited heat generation.

[0006] Yet another object of the present invention is to provide a cost-effective tire with suitable sound deadening and sealing characteristics.

Means for Solving the Problems

[0007] The present invention is defined by the independent claims. Further preferred embodiments are defined by the dependent claims, as well as by the following summary and description of the present specification.

[0008] Accordingly, in a first aspect of the present invention, a pneumatic tire is provided. The tire includes a tread portion, two bead portions, two sidewalls extending between the tread portion and the respective bead portions, an inner surface (optionally formed by an inner liner) defining a tire cavity, a layer of sealant covering the inner surface radially below (or radially inward) of the tread portion within the tire cavity, and at least one noise attenuation strip or element that partially covers the sealant and is attached to the sealant, radially inside the layer of sealant and along the circumferential direction. The layer of sealant has at least one plateau region that supports the noise attenuation strip and one or more bottom regions provided laterally in the axial direction of the plateau region, and the plateau region extends radially inward from the bottom region. In other words, the plateau region or regions that support the noise attenuation strip rise radially inward with respect to the bottom region. The tire according to the present invention including a plateau region of sealant below the noise attenuation strip provides a greater amount of sealant below the attenuation strip. The thickness of the sealant in the bottom region laterally of the attenuation strip is smaller than the thickness in the plateau region that improves the cooling of the tire in the bottom region towards the tire cavity. At the same time, the increase in the thickness of the sealant layer in the plateau region can suppress the flow of the sealant between the inner surface of the tire and the noise attenuation strip in the case of puncture, but helps to provide good sealing performance. Thus, when necessary (i.e., below the attenuation strip), a greater sealing thickness is provided, saving costs in these bottom regions and providing a smaller sealing thickness laterally of the attenuation strip to improve the thermal conductivity.

[0009] In one embodiment, the plateau region extends beyond each lateral or axial side of the noise attenuation strip by a length that is at most 20% (or in one embodiment at most 10%) of the total axial width of the layer of the encapsulant. In particular, it may not be desirable to have a plateau region that is much larger than the bottom surface of the noise attenuation strip. This is because this may lead to a decrease in the thermal conductivity of the encapsulant and an increase in cost. Nevertheless, it may be desirable to have a plateau region that extends axially beyond the noise attenuation strip attached to the encapsulation layer in the plateau region. This helps, for example, to ensure that even a slightly misaligned noise attenuation strip is still supported by a sufficient amount of encapsulant.

[0010] In another embodiment, the bottom region extends along the axial sides of the noise attenuation strip over a length that is 20% to 80% of the total axial width of the encapsulation layer. Thus, the bottom region extends over a substantial portion of the surface or width of the layer of the encapsulant.

[0011] In another embodiment, the plateau region extends axially over at least the axial width of the noise attenuation strip. This may help to support the noise attenuation strip well.

[0012] In another embodiment, the plateau region extends axially over at most the axial width of the noise attenuation strip.

[0013] In another embodiment, the plateau region extends axially over a width within the range of 60% to 90% of the axial width of the noise attenuation strip. Such a relatively narrow plateau can save encapsulant and reduce heat generation.

[0014] In another embodiment, the plateau region extends continuously over a width within the range of 60% to 90% of the axial width of the noise attenuation strip. The continuous extension can help to avoid air pockets that may impair cooling.

[0015] In such an embodiment, the plateau region extends radially only downward in the radial direction of the noise attenuation stripe (i.e., not laterally in the axial direction of the noise attenuation stripe).

[0016] In another embodiment, the plateau region extends axially (and preferably continuously) over a width within the range of 60% to 120% of the axial width of the noise attenuation strip. Thus, in such an embodiment, the plateau region may be wider than the axial width of the noise attenuation strip. Furthermore, such a feature may help facilitate the placement of the strip. In another embodiment, the axial width of the layer of the sealing material is within the range of 60% to 95% (preferably 65% to 90%) of the total tire width. The total tire width is determined as the maximum axial (outer) width of the tire in the non-mounted and non-inflated state.

[0017] In another embodiment, the noise attenuation strip comprises a porous material and / or one or more of the following materials: polyurethane foam (e.g., polyether polyurethane, polyester polyurethane), melamine foam, polypropylene foam, foamed rubber (e.g., EPDM, neoprene-based), natural material-based foam (e.g., cellulose, chitosan-based foam), non-woven material (e.g., meltblown, spunlaid or electrospun polyester, polyamide, PE, PET, PP, cellulose, cotton, wool or silk, or felt from natural fibers). In other words, the noise attenuation strip may be made of a porous material. In particular, when using such materials, a thicker sealing material may be desirable within the plateau region to improve puncture sealing performance. The terms damping and dampening are used interchangeably herein.

[0018] In yet another embodiment, a plurality of noise attenuation strips are arranged along the circumferential direction (preferably substantially parallel). By providing a plurality of strips, the size of the continuous area covered by the noise attenuation material can be reduced, and thus the heat generation behavior within the tire above the strip in the radial direction can be improved. Each plateau region to which such a strip is attached may also extend along the circumferential direction.

[0019] In yet another embodiment, the strip extends along a circumferential length corresponding to at least 50% (preferably at least 80%) of the inner circumference of the tire, measured along the inner surface at the axial center of the tire.

[0020] In yet another embodiment, the axial width of the noise attenuation strip is in the range of 20% to 50% of the total axial width of the layer of the sealing material. In particular, it may be desirable to limit the axial width of the noise attenuation strip in order to avoid unnecessary heat generation in the region of the tire where the noise attenuation element is attached. Generally, the noise attenuation strip can have a polygon, such as a rectangular cross-section, in non-limiting examples.

[0021] In yet another embodiment, the plateau region has a substantially constant thickness. Substantially constant thickness shall mean herein that the thickness does not deviate by more than 10% (or even more than 5%) from the average thickness value.

[0022] In yet another embodiment, the thickness of the plateau region is at least 15%, preferably at least 20% greater than the thickness of the bottom region. Generally, the thickness of the layer of the sealing material is measured perpendicular to the inner surface of the tire (where the sealing material is attached), for example, perpendicular to the inner liner if present. When a region, particularly the bottom region, has a varying thickness (e.g., varying along the transverse or axial direction), the thickness should be understood as the average thickness. The term transverse direction shall mean herein to include, for example, the axial and circumferential directions.

[0023] In yet another embodiment, the thickness of the plateau region is at most 100% greater than the thickness of the bottom region. For example, the thickness of the plateau region can be 15% to 100% greater than the thickness of the bottom region. The thickness of the plateau region can be 20% to 90% thicker than the thickness of the bottom region, 30% to 80% thicker than the thickness of the bottom region, or 40% to 70% thicker than the thickness of the bottom region.

[0024] In yet another embodiment, the bottom region preferably has a substantially constant sealant thickness measured perpendicular to (and along) the inner surface over at least 80% of its axial width. The definition of substantially constant thickness has already been given above.

[0025] In yet another embodiment, the layer of the sealant has a shoulder region that extends (laterally) between the plateau region and the bottom region. In other words, the shoulder region may be adjacent to the plateau region and / or the bottom region.

[0026] In yet another embodiment, each of the shoulder regions extends axially over a length less than 10% of the axial width of the layer of the sealant.

[0027] In yet another embodiment, the noise attenuation strip does not include a coating and / or foil facing the layer of the sealant. In particular, such an embodiment helps to provide a cost - effective tire.

[0028] In yet another embodiment, the noise attenuation strip is a polymer foam element having a density in the range of 0.01 g / cm 3 ~1 g / cm 3

[0029] ​In yet another embodiment, the noise attenuation strip or material can be composed of one or more of polyurethane foam, polyethylene foam, foamed rubber, etc. Suitable polyurethane foams are typically made by the polymerization of diisocyanates and polyols in the presence of a suitable blowing agent. In the practice of the present invention where natural rubber, synthetic polyisoprene rubber, polybutadiene rubber, nitrile rubber, and styrene-butadiene rubber foams are commonly used, a wide variety of rubber foams can be utilized. Such foamed rubber is typically made by foaming natural or synthetic rubber latex with a chemical blowing agent. The chemical blowing agent will typically be an azo compound such as azodicarbonamide, a hydrazine compound, a carbazide, a tetrazole, a nitroso compound, and / or a bicarbonate, such as sodium bicarbonate.

[0030] In another embodiment, the noise attenuation element is made of an open-cell foamed material. Preferably, such a material contains 55% to 95% (or preferably 60% to 90%) open cells (of all the cells) in the material. Open cells can be understood as cells having at least one opening. In other words, open cells are not completely blocked or not completely surrounded by cell walls. Closed-cell foams do not fall within the above range because most of the cells of this type are blocked. Completely or almost completely reticulated foams do not fall within the range because they have few walls and rather form an open lattice. Whether the cells are open (i.e., blocked or not) can be determined, for example, by optical microscopy, SEM, or NMR. The cell size can typically range from 10 μm to 1 mm (maximum diameter).

[0031] In another embodiment, the noise attenuation material is applied and / or used to attenuate tire cavity noise, particularly in the range of 100 Hz to 300 Hz, or in the range of 100 Hz to 200 Hz or 200 Hz to 300 Hz. As referred to herein, the term tire cavity is a volume enclosed by the inner surface of the tire (or the inner liner of the tire if present), particularly in the unmounted and non-inflated state, and blocked by a (virtual) circumferential annular plane that contacts the radially innermost edges of both bead portions.

[0032] In yet another embodiment, the pneumatic tire further comprises a carcass and a belt portion disposed between the tread portion and the carcass.

[0033] In yet another embodiment, the layer of the sealing material is particularly for forming the layer of the sealing material and / or more specifically for forming an axially continuous layer of the sealing material. i) a plurality of sealing material strips that are axially adjacent and circumferentially extend along the inner surface of the tire around the axis of the tire; ii) one or more sealing material strips spirally wound along the inner surface of the tire around the axis of the tire; and includes or is made from them.

[0034] Since these strips may have a cross-section other than rectangular, such as a substantially elliptical, substantially circular, or substantially polygonal cross-section, adjacent such strips to each other can result in a roughness of the surface having a wavy surface profile. The plateau region and the bottom region may exhibit such a slight surface pattern resulting from manufacturing.

[0035] In yet another embodiment, the sealant strip has a greater thickness in the plateau region than in the bottom region (e.g., corresponding to the embodiments of the thickness of the layer described above). Alternatively or additionally, a plurality of sealant strips or a layer of sealant strips is (radially) laminated on top of the plateau region (e.g., so as to form the plateau region). For example, this may be two layers of strips to be laminated. Such an arrangement is particularly useful for providing the plateau region extending from the bottom region.

[0036] In yet another embodiment, one or more sealant strips are arranged spirally (e.g., at an angle of less than 5° or less than 2° with respect to the equatorial plane of the tire) or substantially circumferentially (i.e., at an angle of about 0° or 0° with respect to the equatorial plane of the tire) along the inner surface of the tire.

[0037] In yet another embodiment, the damping strip extends around the (central) axis of the tire. In other words, the damping strip can be attached spirally to the sealing layer.

[0038] In yet another embodiment, the plateau region has a (radial) thickness in the range of 3 mm to 10 mm (preferably from 3 mm or 4 mm to 8 mm), and the bottom region has a thickness in the range of 2 mm to 6 mm (preferably 3 mm to 5 mm). Preferably, the difference in thickness is at least 0.5 mm, at least 0.8 mm, or even at least 1 mm, or even at least 1.5 mm. Additionally or alternatively, the difference in thickness may be at most 3 mm, preferably at most 2 mm, or at most 1.5 mm.

[0039] In yet another embodiment, the noise damping strip adheres (directly) to the sealant. In other words, there is no additional adhesive or adhesive at the interface between the sealant and the noise damping element. Rather, it is the adhesiveness of the sealant that holds the noise damping strip in place.

[0040] In yet another embodiment, the sealing material is one or more of a butyl rubber-based composition, a polybutene-based composition, a polyisoprene-based composition, a natural rubber-based composition, a polyurethane-based composition, an emulsion styrene butadiene rubber-based composition, an EPDM-based composition, and a silicone-based composition. For example, the sealing material may be a blend of butyl rubber and polyisobutylene, as described in U.S. Patent No. 4,895,610. The teachings of U.S. Patent No. 4,895,610 are incorporated herein by reference for the purpose of describing such blends and the methods by which they can be incorporated into tires. In another embodiment, the sealing material can be composed of a foamed solid containing a foamed graphene structure and microspheres, as described in U.S. Patent No. 9,802,446. The teachings of U.S. Patent No. 9,802,446 are incorporated herein by reference for the purpose of describing such a sealing material. In another embodiment, the sealing material composition can include at least one non-halogenated butyl rubber and 2,2'-dibenzamide-diphenyl disulfide. The sealing material composition has a viscosity that allows the sealing material composition to be incorporated into the tire during the tire assembly process and results in a degraded sealing material composition that can flow into and seal a puncture in the tire. This sealing composition is described in more detail in U.S. Patent No. 8,360,122. The teachings of U.S. Patent No. 8,360,122 are incorporated herein by reference for the purpose of describing such a sealing composition.

[0041] In a second aspect of the present invention, a pneumatic tire is provided. The tire includes a tread portion, two bead portions, two sidewalls extending between the tread portion and the respective bead portions, an inner surface defining a tire cavity, a layer of sealing material covering the inner surface radially below the tread portion within the tire cavity, at least one noise attenuation element partially covering the sealing material radially inside the layer of sealing material and attached to the sealing material. The layer of sealing material has at least one plateau region supporting the noise attenuation element and one or more bottom regions provided laterally beside the plateau region, and the plateau region extends radially inward from the bottom region. The layer of sealing material includes A) one or more sealing material strips spirally wound along the inner surface of the tire around the axis of the tire, or B) a plurality of axially adjacent sealing material strips extending circumferentially along the inner surface of the tire around the axis of the tire (so as to form the layer of sealing material). The advantages of providing a plateau region have already been described above. Further, the provision of the layer of sealing material by one or more (substantially parallel) strips enables the efficient production of the plateau region and the bottom region having different thicknesses, which is particularly desirable.

[0042] In one embodiment, the sealing material strip is thicker in the plateau region than in the bottom region. This application method enables the easy provision of the plateau region in mass production.

[0043] In another embodiment, multiple layers of the sealing material strip are laminated on the plateau region. This is another preferred method for providing a plateau region, especially in mass production.

[0044] In yet another embodiment, the noise attenuation element has one or more of the shapes of a strip, a block, and a sheet. The shape can be selected based on a specific application. The noise attenuation strip may have the advantage of being more easily applicable in mass production, especially when a relatively large amount of noise attenuation material is required.

[0045] In yet another embodiment, the noise attenuation element is a noise attenuation foam block or sheet, and a plurality of such blocks or sheets are preferably spaced apart from each other and attached to the sealing layer.

[0046] In yet another embodiment, the plateau region extends across each lateral or axial side of the noise attenuation element for a length of up to 20% (or in one embodiment up to 10%) of the total axial width of the layer of the sealing material beyond the noise attenuation element. In particular, it may not be desirable to have a plateau region that is much larger than the bottom surface of the noise attenuation element. This is because this may lead to a decrease in the thermal conductivity of the sealing material and an increase in cost. Nevertheless, it may be desirable to have a plateau region that extends laterally or axially beyond the noise attenuation element attached to the sealing layer in the plateau region. This helps to ensure that, for example, even a slightly misaligned noise attenuation strip is still supported by a sufficient amount of the sealing material.

[0047] In another embodiment, the plateau region extends laterally or axially across at least the lateral or axial width of the noise attenuation element.

[0048] In another embodiment, the plateau region extends laterally or axially across at most the lateral or axial width of the noise attenuation element.

[0049] In another embodiment, the plateau region extends laterally or axially across a width within the range of 60% to 90% of the lateral or axial width of the noise attenuation element.

[0050] In another embodiment, the plateau region extends continuously laterally or axially across a width within the range of 60% to 90% of the lateral or axial width of the noise attenuation element.

[0051] In such an embodiment, the plateau region extends only radially downward of the noise attenuation element (i.e., not axially laterally of the noise attenuation element).

[0052] In another embodiment, the plateau region extends (preferably continuously) laterally or axially over a width within the range of 60% to 120% of the lateral or axial width of the noise attenuation element. Thus, in such an embodiment, the plateau region may be wider than the lateral width or the axial width of the noise attenuation element.

[0053] In another embodiment, the bottom region extends laterally or axially of the noise attenuation element over a length that is 20% to 80% of the total axial width of the sealing layer. Thus, the bottom region extends over a substantial portion of the surface or width of the layer of the sealing material.

[0054] In another embodiment, the axial width of the layer of the sealing material is within the range of 60% to 95% (preferably 65% to 90%) of the total tire width.

[0055] In another embodiment, the noise attenuation element includes a material as already described above with respect to the noise attenuation strip.

[0056] In yet another embodiment, a plurality of noise attenuation strips are arranged circumferentially (preferably substantially parallel).

[0057] In yet another embodiment, the noise attenuation strip or the plurality of strips extend along a circumferential length corresponding to at least 50% (preferably at least 80%) of the inner circumference of the tire measured along the inner surface at the axial center of the tire.

[0058] In yet another embodiment, the axial width of the noise attenuation element is in the range of 20% to 50% of the total axial width of the layer of the sealing material. In particular, in order to avoid unnecessary heat generation in the region of the tire where the noise attenuation element is attached, it may be desirable to limit the axial width of the noise attenuation element.

[0059] In yet another embodiment, the plateau region has a substantially constant thickness. By substantially constant thickness, it is meant here that the thickness does not deviate by more than 10% (or even more than 5%) from the average thickness value (here, across the plateau region).

[0060] In yet another embodiment, the thickness of the plateau region is at least 15%, preferably at least 20% greater than the thickness of the bottom region. Generally, the thickness of the layer of the sealing material is measured perpendicular to the inner surface of the tire (where the sealing material is attached), for example, perpendicular to the inner liner if present. When a region, particularly the bottom region, has a varying thickness (e.g., varying along the lateral direction), the thickness should be understood as the average thickness.

[0061] In yet another embodiment, the thickness of the plateau region is at most 100% greater than the thickness of the bottom region. For example, the thickness of the plateau region can be 15% to 100% greater than the thickness of the bottom region. The thickness of the plateau region can be 20% to 90% thicker than the thickness of the bottom region, 30% to 80% thicker than the thickness of the bottom region, or 40% to 70% thicker than the thickness of the bottom region.

[0062] In yet another embodiment, the bottom region preferably has a substantially constant sealing material thickness measured perpendicular to the inner surface (along and) over at least 80% of its (maximum) axial width. The definition of substantially constant thickness has already been given above.

[0063] In yet another embodiment, the layer of the sealing material has a shoulder region that extends (horizontally) between the plateau region and the bottom region. In other words, the shoulder region may be adjacent to the plateau region and / or the bottom region.

[0064] In yet another embodiment, each of the shoulder regions extends horizontally, particularly axially, over a length of less than 10% of the axial width of the layer of the sealing material.

[0065] In yet another embodiment, the noise attenuation element does not include a coating and / or foil facing the layer of the sealing material. In particular, such an embodiment helps to provide a cost-effective tire.

[0066] In yet another embodiment, the noise attenuation element is a polymer foam element having a density in the range of 0.01 g / cm 3 ~1 g / cm 3 .

[0067] In yet another embodiment, the noise attenuation element can be made of the same material as that already described for the noise attenuation strip.

[0068] In yet another embodiment, the sealing material strip, in other words the bead, together forms the layer of the sealing material.

[0069] In yet another embodiment, one or more sealing material strips are arranged spirally (e.g., at an angle of less than 5° or less than 2° with respect to the equatorial plane (EP) of the tire) or substantially circumferentially (i.e., at an angle of about 0° or 0° with respect to the equatorial plane of the tire) along the inner surface of the tire.

[0070] In yet another embodiment, the attenuation strip extends around the (central) axis of the tire. In other words, the attenuation strip is spirally attached to the sealing layer.

[0071] In yet another embodiment, the plateau region has a (radial) thickness in the range of 3 mm to 10 mm (preferably from 3 mm or 4 mm to 8 mm), and the bottom region has a thickness in the range of 2 mm to 6 mm (preferably 3 mm to 5 mm). Preferably, the difference in thickness is at least 0.5 mm, at least 0.8 mm, or at least 1 mm, or at least 1.5 mm. Additionally, or alternatively, the difference in thickness may be at most 3 mm, preferably at most 2 mm, or at most 1.5 mm.

[0072] In yet another embodiment, the noise attenuation element adheres (directly) to the sealant. In other words, there is no additional adhesive or adhesives at the interface between the sealant and the noise attenuation element. Rather, it is the adhesiveness of the sealant material that holds the noise attenuation strip in place.

[0073] In a third aspect of the present invention, a method for manufacturing a pneumatic tire is provided. This method includes one or more of the following steps: (1) Providing a pneumatic tire (particularly an uncured pneumatic tire) comprising two (axially opposed) bead portions, a tread portion, and two sidewalls connecting or joining each bead portion to the tread portion; (2) Curing (i.e., vulcanizing) the tire; (3) Applying one or more sealant strips onto the inner surface of the cured tire (e.g., on the inner liner) to form a layer of sealant on the inner surface, forming at least one plateau region of the sealant within the layer of sealant, and forming by extending from one or more bottom regions within the layer of sealant; (4) Attaching at least one noise attenuation element to the at least one plateau region.

[0074] In one embodiment, the layer of sealant is formed by applying one or more sealant strips spirally along the inner surface of the tire around the axis of the tire.

[0075] In another embodiment, the step of forming the layer of the sealing material includes rotating the tire about its axis of rotation and extruding the sealing material strip onto the inner surface of the rotating tire.

[0076] In yet another embodiment, the strip is extruded by an extrusion head and / or die that is movable or moved in the axial direction of the tire during the extrusion of the sealing material strip. Together with the rotation of the tire, a circumferential or helical strip can be applied to the inner surface of the tire.

[0077] In another embodiment, the layer of the sealing material is formed by applying (simultaneously or subsequently) a plurality of axially adjacent sealing material strips that extend circumferentially along the inner surface of the tire around the axis of the tire.

[0078] In yet another embodiment, the strip is extruded or applied with a greater thickness in the plateau region than in the bottom region.

[0079] In yet another embodiment, a plurality of strip layers (especially two or three layers) are laminated on top of the plateau region.

[0080] In yet another embodiment, the sealing material strip has an axial width in the range of 2 mm to 15 mm, preferably 5 mm to 12 mm, or more preferably 7.5 mm to 12 mm, or 8 mm to 15 mm.

[0081] In yet another embodiment, the thickness of the sealing material strip is at least 15% greater in the plateau region than in the bottom region.

[0082] In yet another embodiment, the greater thickness of the sealant strip in the plateau region is provided by one or more of extruding the sealant strip faster than the bottom region, extruding the sealant strip at a higher pressure than the bottom region, using a die (for extrusion) having a larger exit diameter, using an extrusion die having an adjustable, and in particular expandable, exit diameter, and rotating the tire more slowly about its axis of rotation when extruding the strip in the plateau region than when extruding the strip in the bottom region.

[0083] Particular attention is drawn, in particular, to the application of the sealant strip described above with respect to the use of a noise damping strip extending substantially circumferentially. However, even when using noise damping blocks, circumferentially discontinuous strips or sheets, it would also be possible to form a bottom region circumferentially between the plateau regions, for example by the method of the above-described embodiments.

[0084] In yet another embodiment, the method further comprises applying a first layer of one or more sealant strips, wherein the first layer of strips of the sealant layer forms the bottom region of the bottom region and the plateau region, and applying a second layer of one or more sealant strips, wherein the second layer of the sealant strip forms the upper part of the plateau region.

[0085] In general, the different aspects and embodiments of the invention and the features of this description can be combined with each other.

[0086] The structure, operation, and advantages of the present invention will become more apparent by considering the following description in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0087]

Figure 1

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DETAILED DESCRIPTION OF THE INVENTION

[0088] Figure 1 is a schematic cross-sectional view of a tire 1 according to a non-limiting embodiment of the present invention. The tire 1 of the embodiment has a tread portion 10, two bead portions 3, and two sidewalls 2 that join the outer axial edges of the tread portion 10 to the respective bead portions 3. Such a tire structure is as known in the tire art. The tire 1 has an inner surface that defines a tire cavity 6. Optionally, the tire may have an inner liner (not shown in FIG. 1) that defines the tire cavity 6. A layer 30 of a sealing material is provided on the inner side or inner surface of the tire 1 in a region opposite to the tread portion 10. The layer of the sealing material preferably extends in the circumferential direction c and the axial direction a along the inner surface of the tire 1. A noise damping element such as a foam strip 20 is attached to the layer 30 of the sealing material in a plateau portion or plateau region 40 of the layer 30 of the sealing material. In this non-limiting embodiment, the foam strip 20 extends in the circumferential direction and is directly attached to the layer 30 of the sealing material on the radially inner side of the plateau region 40. Axially laterally of the plateau region 40 or adjacent to the plateau region 40, the layer of the sealing material includes two bottom portions or regions 50, in which the layer 30 of the sealing material has a thickness thinner than that of the plateau region 40. In particular, the plateau region 40 is not created by an elevation of the inner surface of the tire 1, for example, the inner liner in this example. In this embodiment, the foam strip 20 is arranged along the axial centerline of the tire 1, or in other words, substantially parallel to the equatorial plane EP of the tire 1.

[0089] For clarity, the axial direction a, the circumferential direction c, and the radial direction r are shown in FIG. 1 as commonly used in the description of the geometric shape of a tire. The term "direction" is not limited to a specific orientation unless otherwise indicated in this specification. The axial direction a can be understood as a direction parallel to the rotation axis of the tire 1. The circumferential direction c is concentric with the rotation axis of the tire 1, and the radial direction r extends radially from the latter as common in the tire art.

[0090] As can be seen in FIG. 1, the amount of the sealing material is less in the bottom region 50 than in the plateau region 40. Limiting the amount of the sealing material on the axial sides of the foam strip 20 reduces costs and improves the thermal conductivity of the tire 1 towards the tire cavity 6. The greater material thickness in the plateau region 40 improves the sealing performance under the foam strip 20. In particular, the inventors have found that if the thickness of the thin sealing material supporting the foam strip 20 is the same as that of the bottom region 50, the desired sealing performance is not necessarily obtained.

[0091] FIG. 2 shows another embodiment of the tire 1'. The tire 1' has, similar to the tire 1 of FIG. 1, a tread portion 10, a sidewall 2, a bead portion 3, a cavity 6, and a layer 31 of a sealing material. In contrast to the embodiment shown in FIG. 1, the embodiment of FIG. 2 has two plateau regions 41, 42 and three bottom regions 51, 52, 53. Foam strips 21, 22 are attached to each of the plateau regions 41, 42. Similar to the first embodiment, the layer 31 of the sealing material has a smaller thickness in the bottom regions 51, 52, 53, particularly when measured perpendicular to the inner surface of the tire 1' than in the plateau regions 41, 42.

[0092] As shown in FIG. 2, the plateau regions 41, 42 can extend axially slightly wider than the axial width of the foam strips 21, 22. This can help facilitate the positioning and / or application of the strips 21, 22 onto the sealing material in the plateau regions 41, 42.

[0093] FIG. 3 shows a schematic top view of the layer 30 of the sealing material of FIG. 1 within the tire cavity. The foam strip 20 is attached to the layer 30 of the sealing material in the plateau region 40. The bottom region 50 is provided on both axial sides of the plateau region 40.

[0094] Figure 4 shows another schematic top view, namely, the top view of the embodiment already discussed with respect to Figure 2. As can be seen in Figure 4, the two foam strips 21, 22 are attached to the layer 31 of the sealing material in the plateau regions 41 and 42. On both sides of each of the plateau regions 41, 42, respective bottom regions 51, 52, 53 are provided.

[0095] According to the embodiment of Figure 5, instead of the strip-shaped noise attenuation element, a block-shaped noise attenuation element is provided on the layer 32 of the sealing material. Thus, two noise attenuation blocks 23, 23', for example foam blocks, are arranged on the plateau regions 43, 43'. In this embodiment, the blocks 23, 23' and the plateau regions 43, 43' have a substantially rectangular shape. However, the present invention is not limited to such a shape. Rather, the shape of the block or sheet of the noise attenuation material can have other shapes, and the shape of the corresponding plateau region can be selected accordingly. The plateau regions 43, 43' are surrounded by the bottom portion 53'. In other words, the plateau regions 43, 43' extend or protrude from the laterally adjacent bottom portions. In particular, the "lateral direction" includes the axial direction and / or the circumferential direction. The noise attenuation blocks 23, 23' are shown at the axial center position of the layer 32 of the sealing material, but other positions, for example, an arrangement adjacent to each other in the axial direction are possible.

[0096] Figure 6 schematically shows again the arrangement already shown in Figure 1 and includes more details about an example of the potential use and structure of the layer 30 of the sealing material. In this embodiment, the layer 30 of the sealing material includes a plurality of strips S bi and S pi which are extruded or applied to the inner surface (not shown) of the tire with a first thickness substantially corresponding to the thickness of the bottom portion 50, and the strip S bi piIt is extruded or applied at a second thickness that substantially corresponds to the thickness of the Plateau region 40. Thereafter, the foam strip 20 is attached onto the Plateau region 40. Preferably, the strips contact each other and / or have substantially no overlap so as to provide a smooth and / or continuous radially inner surface. In another embodiment (not shown), a first layer of strips having substantially the same thickness in regions 40 and 50 is applied, and a second layer of strips is applied only in region 40 to produce a Plateau region 40 that is thicker than the bottom region 50.

[0097] Figure 7 shows another embodiment of the tire 1’’ having the elements already shown in Figures 1 and 2. In contrast to those embodiments, the noise attenuation strip 24 is supported by the Plateau region 44 of the sealant layer 34. The Plateau region 44 does not extend over the entire axial width of the noise attenuation strip 24. Providing the Plateau region 44 radially below the noise attenuation strip 24 with an axial extent that is narrower than the axial width of the strip 24 helps to conserve sealant while providing sufficient sealing characteristics. Also, the heat generation property below the strip 24 is further reduced. The bottom region 54 has a thickness that is thinner than the Plateau region 44, as described in connection with the embodiments of Figures 1 and 2.

[0098] Figure 8 shows yet another embodiment of the tire 1’’’. With respect to Figure 8, the same reference numerals as in Figure 1 are used where applicable. In the embodiment of Figure 8, the sealant layer 35 has a plurality (here two) of Plateau regions 45, 46 that extend radially from the bottom regions 55, 56, 57. Such an embodiment is particularly advantageous in the case of relatively wide noise attenuation strips such as the strip 25, helping to conserve sealant while still being able to guarantee appropriate puncture sealing characteristics.

Claims

Claim 1 A pneumatic tire having a tread portion (10), two bead portions (3), two sidewalls (2) extending between the tread portion (10) and the respective bead portions (3), an inner surface defining a tire cavity (6), a layer of sealing material (30, 31, 34, 35) covering the inner surface radially below the tread portion (10) within the tire cavity (6), and at least one noise attenuation strip (20, 21, 22, 24, 25) disposed radially inside the layer of sealing material (30, 31, 34, 35), extending along the circumferential direction, partially covering the sealing material, and attached to the sealing material. The layer of sealing material (30, 31, 34, 35) has at least one plateau region (40, 42, 45, 46) supporting the noise attenuation strip (20, 21, 22, 24, 25) and one or more bottom regions (50, 51, 52, 54, 56) provided laterally in the axial direction of the plateau region (40, 41). The plateau region (40, 42, 45, 46) extends radially inward from the bottom region (50, 51, 52, 54, 56). Claim 2 The plateau regions (40, 41, 42, 44, 45, 46) extend for a length of up to 20% of the total axial width of the layer of sealing material (30, 31, 34, 35) beyond each axial side surface of the noise attenuation strip (20, 21, 22, 24, 25). And / or, the bottom regions (50, 51, 52, 53, 54, 55, 56) extend along the axial sides of the noise attenuation strip (20, 21, 22, 24, 25) for a length ranging from 20% to 80% of the total axial width of the layer of sealing material (30, 31, 34, 35). And / or, the plateau regions (40, 41, 42, 44, 45, 46) have a substantially constant radial thickness. The pneumatic tire according to Claim 1. Claim 3 The plateau regions (40, 41, 42, 44, 45, 46) extend axially over a width within the range of 60% to 120% of the axial width of the noise attenuation strip (20, 21, 22, 24, 25). The pneumatic tire according to Claim 1 or 2. Claim 4 The noise attenuation strip (20, 21, 22, 24, 25) extends along a circumferential length corresponding to at least 50% of the inner circumference of the tire (1, 1', 1'', 1''') measured along the inner surface at the axial center of the tire (1, 1', 1'', 1'''). And / or, the axial width of the noise attenuation strip (20, 21, 22, 24, 25) is within the range of 20% to 50% of the total axial width of the layer (30, 31, 34, 35) of the sealing material. The pneumatic tire according to any one of claims 1 to 3.

5. The layer (30, 31, 34, 35) of the sealing material has a shoulder region extending between the plateau region (40, 41, 42, 44, 45, 46) and the bottom region (50, 51, 52, 53, 54, 55, 56), and the shoulder region extends axially over less than 10% of the axial width of the layer (30, 31, 34, 35) of the sealing material. The pneumatic tire according to any one of claims 1 to 4.

6. The bottom region (50, 51, 52, 53, 54, 55, 56) has a substantially constant sealing material thickness measured perpendicular to the inner surface of the tire (1, 1', 1'', 1'''). The pneumatic tire according to any one of claims 1 to 5.

7. The noise attenuation strip (20, 21, 22, 24, 25) does not include a coating or foil facing the layer (30, 31, 34, 35) of the sealing material. The pneumatic tire according to any one of claims 1 to 6.

8. The noise attenuation strip (20, 21, 22, 24, 25) includes a porous material, and / or, the noise attenuation strip (20, 21, 22, 24, 25) is a polymer foam strip, and / or, the sealing material is one or more of a butyl rubber-based composition, a polyisoprene-based composition, a natural rubber-based composition, a polyurethane-based composition, a polybutene-based composition, an emulsion styrene butadiene rubber-based composition, an EPDM-based composition, and a silicone-based composition. The pneumatic tire according to any one of claims 1 to 7.

9. The thickness of the plateau region (40, 41, 42, 44, 45, 46) is at least 15% greater than the thickness of the bottom region (50, 51, 52, 53, 54, 55, 56), and / or at most 50% greater than the thickness of the bottom region (50, 51, 52, 53, 54, 55, 56). The pneumatic tire according to any one of claims 1 to 8.

10. The layer of the sealing material (30, 31, 34, 35) includes one of: i) a plurality of sealing material strips adjacent in the axial direction and extending circumferentially along the inner surface of the tire (1, 1', 1'', 1''') around the axis of the tire (1, 1', 1'', 1'''); ii) one or more sealing material strips wound spirally along the inner surface of the tire (1, 1', 1'', 1''') around the axis of the tire (1, 1', 1'', 1'''). The sealing material strip is thicker in the plateau region (40, 41, 42, 44, 45, 46) than in the bottom region (50, 51, 52, 53, 54, 55, 56), and / or is optionally laminated on the plateau region (40, 41, 42, 44, 45, 46). The pneumatic tire according to any one of claims 1 to 9.

11. The plateau region (40, 41, 42, 44, 45, 46) has a radial thickness in the range of 3 mm to 10 mm. and / or the bottom region (50, 51, 52, 53, 54, 55, 56) has a thickness in the range of 2 mm to 6 mm. and / or the difference in thickness between the plateau region (40, 41, 42, 44, 45, 46) and the bottom region (50, 51, 52, 53, 54, 55, 56) is at least 0.5 mm. The pneumatic tire according to any one of claims 1 to 10.

12. A tread portion (10), two bead portions (3), two sidewalls (2) extending between the tread portion (10) and the respective bead portions (3), an inner surface defining a tire cavity (6), a layer of sealing material (30, 31, 32, 34, 35) covering the inner surface radially downward of the tread portion (10) in the tire cavity (6) in the radial direction, and at least one noise damping element (20, 21, 22, 23, 23', 24, 25) partially covering the sealing material and attached to the sealing material, inside the sealing material layer (30, 31, 34, 35) in the radial direction. The layer of sealing material (30, 31, 32, 34, 35) has at least one plateau region (40, 41, 42, 43, 43', 44, 45, 46) supporting the noise damping element and one or more bottom regions provided laterally on the sides of the plateau region (40, 41, 42, 43, 43', 44, 45, 46), and the plateau region (40, 41, 42, 43, 43', 44, 45, 46) extends radially inward from the bottom region (50, 51, 52, 53, 53', 54, 55, 56). The layer of sealing material (30, 31, 32, 34, 35) is i) one or more sealing material strips spirally wound along the inner surface of the tire (1, 1', 1'', 1''') around the axis of the tire, or ii) a pneumatic tire having a plurality of sealing material strips adjacent in the axial direction and extending circumferentially along the inner surface of the tire (1, 1', 1'', 1''') around the axis of the tire so as to form the layer of sealing material (30, 31, 32, 34, 35).

13. The pneumatic tire according to claim 12, wherein the front sealing material strip is thicker in the plateau region (40, 41, 42, 43, 43', 44, 45, 46) than in the bottom region (50, 51, 52, 53, 53', 54, 55, 56), and the thickness of the sealing material strip is at least 15% greater in the plateau region (40, 41, 42, 43, 43', 44, 45, 46) than in the bottom region (50, 51, 52, 53, 53', 54, 55, 56).

14. A plurality of layers of the strip are laminated on the plateau regions (40, 41, 42, 43, 43', 44, 45, 46), and / or the sealing strip has an axial width within the range of 2 mm to 15 mm, the pneumatic tire according to claim 12 or 13.

15. A method for manufacturing a pneumatic tire (1, 1', 1'', 1'''), comprising: a) providing an uncured pneumatic tire including two bead portions (3), a tread portion (10), and two sidewalls (2) connecting the respective bead portions to the tread portion (10); b) curing the tire (1, 1', 1'', 1'''); c) applying one or more sealing strips onto the inner surface of the cured tire (1, 1', 1'', 1''') to form a layer of sealing material (30, 31, 32, 34, 35), and forming at least one plateau region (40, 41, 42, 43', 44, 45, 46) of the sealing material in the layer of the sealing material such that the plateau region (40, 41, 42, 43', 44, 45, 46) extends from one or more bottom regions (50, 51, 52, 53, 53', 54, 55, 56) of the layer of the sealing material (30, 31, 32, 34, 35); d) attaching at least one noise damping element (20, 21, 22, 23, 23', 24, 25) to the at least one plateau region (40, 41, 42, 43', 44, 45, 46).

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