Tire band having a filament with a non-circular cross-section

Abstract

The non-pneumatic tire includes a lower ring having a first diameter and an upper ring having a second diameter greater than the first diameter. The upper ring is substantially coaxial with the lower ring. A support structure connects the lower ring to the upper ring. A circumferential tread is attached to the upper ring. The circumferential tread includes a tread layer and a tread band. The tread band includes a filament assembly including a plurality of individual filaments having a non-circular cross section. The filaments are constructed and arranged such that the filaments have a packing density of at least 92% within the filament assembly.

Description

Technical Field

[0001] The present disclosure relates to a tire band including filaments. More specifically, the present disclosure relates to a tire band having filaments with a non-circular cross-section.

Background Art

[0002] Various tire structures have been developed that enable a tire to run in a non-inflated or under-inflated state. Pneumatic tires do not require inflation, but "run-flat tires" can continue to operate relatively fast for a long time even after being punctured and partially or completely deflated. Pneumatic tires may include a support structure such as spokes or webbing that connect a lower ring to an upper ring. In some pneumatic tires, the circumferential tread can be attached to the upper ring of the tire.

[0003] The circumferential tread may include a tread band. The tread band can be a single layer or multi-layer band of material. Such a tread band may also be referred to as a shear band, a shear element, or a thin annular high-strength band element. When used in a pneumatic tire in a non-pressurized state or a partially pressurized state or a non-pneumatic tire, the shear element acts as a structural compression member. When used in a fully pressurized pneumatic tire, the shear element acts as a tension member.

Summary of the Invention

Problems to be Solved by the Invention

[0004] In one embodiment, the non-pneumatic tire includes a lower ring having a first diameter and an upper ring having a second diameter greater than the first diameter. The upper ring is substantially coaxial with the lower ring. A support structure connects the lower ring to the upper ring. A circumferential tread is attached to the upper ring. The circumferential tread includes a tread layer and a tread band. The tread band includes a filament assembly including a plurality of individual filaments having a non-circular cross-section. The filaments are configured and arranged such that the filaments have a packing density of at least 92% within the filament assembly.

[0005] In another embodiment, a method of manufacturing a non-pneumatic tire includes providing a lower ring having a first diameter and an upper ring having a second diameter greater than the first diameter. The method further includes connecting the lower ring to the upper ring using a support structure. The method further includes forming a plurality of individual filaments having a non-circular cross-section and assembling the plurality of individual filaments into a tread band. Further, the method includes applying a tread layer to the tread band to form a circumferential tread and attaching the circumferential tread to the upper ring.

[0006] In yet another embodiment, the non-pneumatic tire includes a lower ring having a first diameter and an upper ring having a second diameter greater than the first diameter. The upper ring is substantially coaxial with the lower ring. A support structure connects the lower ring to the upper ring. A circumferential tread is attached to the upper ring. The circumferential tread includes a tread layer, at least one non-extensible layer, and at least one extensible layer. The at least one non-extensible layer and the at least one extensible layer are disposed between the tread layer and the upper ring along the radial direction of the non-pneumatic tire. The non-extensible layer includes a filament assembly including a plurality of individual filaments having a non-circular cross-section. Each circle circumscribing each filament has a diameter of 0.1 to 25 mm. Each filament has a coating with a thickness of 0 to 10 mm.

Brief Description of the Drawings

[0007] In the accompanying drawings, structures that illustrate representative embodiments of the claimed invention are depicted, along with the detailed description provided below. Like elements are identified by like reference numerals. It should be understood that an element shown as a single component may be replaced by a number of components, and an element shown as a number of components may be replaced by a single component. The drawings are not to scale, and the ratios of certain elements may be exaggerated for illustration purposes.

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DETAILED DESCRIPTION OF THE INVENTION

[0008] The following includes definitions of selected terms employed herein. The definitions include the scope of the terms and various examples or forms of components that may be used for implementation. The examples are not intended to be limiting. Both the singular and plural forms of the terms may be within the scope of the definitions.

[0009] "Axial" and "axially" refer to a direction parallel to the axis of rotation of the tire.

[0010] "Circumferential" and "circumferentially" refer to a direction extending along the outer peripheral portion of the surface of the tread that is perpendicular to the axial direction.

[0011] "Radial" and "radially" refer to a direction perpendicular to the rotational axis of the tire.

[0012] As used herein, "tread" refers to the portion of the tire that contacts the road or ground at normal inflation and normal load.

[0013] As used herein, "packing density" refers to the ratio of the volume occupied by the filaments to the total volume of the filament assembly.

[0014] Common tire components are described by similar terms used in the following description. However, since the terms naturally have slightly different implications, those skilled in the art should understand that it should not be considered that any one of the following terms can simply be exchanged with another term used in the description of common tire components.

[0015] In this specification, directions are described with reference to the rotational axis of the tire. The terms "upward" and "upwardly" refer to the general direction towards the tread of the tire, and "downward" and "downwardly" refer to the general direction towards the rotational axis of the tire. Thus, when relative directional terms such as "upper" and "lower" or "top" and "bottom" are used in relation to an element, the "upper" or "top" element is spaced closer to the tread than the "lower" or "bottom" element. Additionally, when relative directional terms such as "above" or "below" are used in relation to an element, an element "above" another element is closer to the tread than the other element.

[0016] The terms "inner" and "inward" refer to the general direction towards the equatorial plane of the tire, and the terms "outer" and "outward" refer to the general direction away from the equatorial plane of the tire and towards the sidewalls of the tire. Thus, when relative directional terms such as "inner" and "outer" are used in relation to an element, the "inner" element is spaced closer to the equatorial plane of the tire than the "outer" element.

[0017] Figures 1 - 3 illustrate one embodiment of a non-pneumatic tire 10. The non-pneumatic tire 10 is merely an exemplary drawing and is not intended to be limiting. In the illustrated embodiment, the non-pneumatic tire 10 includes a generally annular lower ring 20. The lower ring 20 can engage a vehicle hub (not shown) for attaching the tire 10 to a vehicle. The lower ring 20 has an inner surface 23 and an outer surface 24 and can be made of a polymer material, an elastomer material, metal, or any other desired material.

[0018] The non-pneumatic tire 10 further includes a generally annular upper ring 30 disposed above the lower ring 20. The upper ring 30 has a diameter larger than that of the lower ring 20 and is substantially coaxial with the lower ring 20. The upper ring 30 has an inner surface 33 and an outer surface 34 and can be made of a polymer material, an elastomer material, metal, or any other desired material. The circumferential tread 70 is attached to the outer surface 34 of the upper ring 30. The circumferential tread 70 can be attached to the upper ring 30 with an adhesive or by using other methods known in the art. As shown in FIG. 2, the upper ring 30 can be configured to deform in the area 48 surrounding and including the footprint area 32 that can reduce vibration and increase ride comfort. Thereby, vibration can be reduced and ride comfort can be improved.

[0019] The support structure 40 connects the lower ring 20 to the upper ring 30. The support structure 40 extends from the outer surface 24 of the lower ring 20 and the inner surface 33 of the upper ring 30. In the illustrated embodiment, the support structure 40 is a webbing. The illustrated webbing 40 has at least two radially adjacent layers 56, 58 of web elements 42 that define a plurality of substantially polygonal openings 50. In an alternative embodiment, the support structure may be a spoke or any other desired arrangement. In an alternative embodiment using a webbing, other web configurations may be provided. For example, the webbing may include fewer or more radially adjacent layers. As another example, the web elements may form openings of any desired shape.

[0020] As shown in FIG. 3, the circumferential tread 70 includes a tread band 72 and a tread layer 74. The tread layer 74 may be made of rubber and may include tread elements (not shown) such as grooves, ribs, blocks, lugs, siping, studs, or any other desired elements. The tread band 72 may include a filament assembly.

[0021] In the illustrated embodiment, the tread band 72 is shown as a single layer. In another embodiment (not shown), the tread band may be a multi-layer band. Such a multi-layer tread band can include one or more layers of substantially non-extensible material. Such a layer may be formed from a metal such as steel. The substantially non-extensible layer may be formed from a sheet of material or by cords or filaments of material. The multi-layer tread band can optionally include a layer of extensible material such as an elastomer. For example, the tread band can include a pair of non-extensible layers separated by a layer of extensible material. The tread band may include a shear band, a shear element, or a band referred to as a thin annular high-strength band element.

[0022] Figure 4 shows a cross-section of a portion of an exemplary filament assembly 200. According to one embodiment, the filament assembly 200 constitutes the entire tread band 72. In an alternative embodiment, the tread band may include other elements in addition to the filament assembly.

[0023] The filament assembly 200 includes a plurality of individual filaments 202. Each of the individual filaments 202 itself may be a single strand of material (i.e., a monofilament) or may include a plurality of strands of material (i.e., a multifilament). The filaments 202 can be made of steel, fabric, or any other desired material. According to one embodiment, each filament may have a coating used to adhere the individual filaments 202 together to form the filament assembly 200. In one embodiment, the coating has a thickness in the range of 0 to 10 mm. In another embodiment, the thickness of the coating is in the range of 0 to 0.25 mm. In another alternative embodiment, the thickness of the coating is in the range of 0.025 to 0.25 mm. In one embodiment, the coating is rubber. In an alternative embodiment, the coating may be a polymer other than rubber, epoxy, or an adhesive. In another alternative embodiment, the filaments may be without a coating. In other alternative embodiments, the individual filaments may be fastened together using mechanical fasteners or any other desired arrangement.

[0024] In the illustrated embodiment, each of the individual filaments 202 has a substantially hexagonal cross-section. The corners 204 of each filament 202 are rounded to improve the fatigue resistance of the filament 202. In an alternative embodiment, the corners may be provided as sharp corners. The illustrated embodiment shows that the central longitudinal axis 206 of each filament is radially aligned (R) with respect to adjacent filaments. Axial direction (A)is offset. In an alternative embodiment, the filaments may have any desired alignment. For example, the central longitudinal axis of each filament is radially offset and is Axial direction aligned with respect to adjacent filaments.

[0025] FIG. 5 shows a cross-section of a portion of another exemplary filament assembly 300. Filament assembly 300 of FIG. 5 is substantially similar to filament assembly 200 of FIG. 4, except for the differences described herein.

[0026] Filament assembly 300 includes a plurality of individual filaments 302. Each of the individual filaments 302 has a substantially square cross-section. The corners 304 of each filament 302 are rounded to improve the fatigue resistance of the filament 302. In an alternative embodiment, the corners may be provided as sharp corners. In the illustrated embodiment, the central longitudinal axis 306 of each filament is aligned radially (R) and is Axial direction (A) also aligned with respect to adjacent filaments. In an alternative embodiment, the filaments may have any desired alignment. For example, the central longitudinal axis of each filament is radially offset and is Axial direction aligned with respect to adjacent filaments. As yet another example, the central longitudinal axis of each filament is aligned radially and is Axial direction offset with respect to adjacent filaments.

[0027] In each of the above examples, the diameter of the circle circumscribing each of the filaments 202, 302 is in the range of 0 to 1 to 25 mm in one embodiment. In an alternative embodiment, the diameter is in the range of 0.35 to 25 mm. In another alternative embodiment, the diameter is in the range of 0.35 to 5 mm.

[0028] Due to the specific cross-sectional shapes of the individual filaments 202, 302 of the filament assemblies 200, 300 shown in FIGS. 4 and 5 respectively, it is possible to achieve a 100% packing density of the filaments. This is compared to a tire having a tread band formed by a plurality of filaments having a circular cross-section that can only achieve a packing density of about 91%. The increased packing density of the filament assemblies 200, 300 in FIGS. 4 and 5 minimizes rolling resistance and heat generation, thereby improving the performance and robustness of the non-pneumatic tire as compared to a non-pneumatic tire that uses filaments with a circular cross-section to form the tread band.

[0029] The above-mentioned 100% packing density of the filaments may be achievable in a filament assembly that uses mechanical fasteners to fix the individual filaments together or that uses uncoated filaments. In a filament assembly that uses a coating on each filament to fix the individual filaments together, a 100% packing density may not be possible due to the presence of the coating. In an exemplary embodiment, the packing density of the filaments is at least 92%. In another embodiment, the packing density is at least 93%. In another alternative embodiment, the packing density is at least 94%. In yet another alternative embodiment, the packing density is at least 95%. In yet another alternative embodiment, the packing density is at least 96%. In yet another alternative embodiment, the packing density is at least 97%. In yet another alternative embodiment, the packing density is at least 98%. In yet another alternative embodiment, the packing density is at least 99%.

[0030] Individual filaments can be formed using any desired process. One non-limiting example of a process for forming individual filaments can include passing a steel cord having a substantially circular cross-section through a die to impart a different geometric shape, such as a hexagonal or square cross-section, to the cord. In one embodiment, this process is performed without adding additional heat to the cord. In another embodiment, a small amount of heat can be added. Another non-limiting exemplary process for forming individual filaments may include swaging. Depending on the process used, it may be easier to form filaments having a hexagonal cross-section compared to filaments having a square cross-section.

[0031] FIG. 6 shows another exemplary embodiment of the non-pneumatic tire 110. The non-pneumatic tire 100 of FIG. 6 is substantially similar to the non-pneumatic tire 10 of FIGS. 1-3, except for the differences described herein. Accordingly, similar features will be identified by similar numbers incremented by only the value of "100".

[0032] The non-pneumatic tire 110 includes a substantially annular lower ring 120 and a substantially annular upper ring 130. The circumferential tread 170 is attached to the upper ring 130. The support structure 140 connects the lower ring 120 to the upper ring 130.

[0033] The circumferential tread 170 includes a tread layer 174, and a non-stretch layer 172 and a stretch layer 176 between the upper ring 130 and the tread layer 174. In the illustrated embodiment, the circumferential tread 170 includes three stretch layers 176a, 176b, 176c alternating between four non-stretch layers 172a, 172b, 172c, 172d. The first non-stretch layer 172a is attached to the upper ring 130, and the fourth non-stretch layer 172d is attached to the tread layer 174. In alternative embodiments, any desired arrangement of stretch layers and non-stretch layers may be provided. For example, the circumferential tread can include three non-stretch layers alternating between four stretch layers, with the first stretch layer attached to the upper ring and the fourth stretch layer attached to the tread layer. As another example, the circumferential tread may include fewer or more stretch layers or non-stretch layers than those shown in FIG. 6.

[0034] Each of the non-stretch layers 172 of the non-pneumatic tire 110 of FIG. 6 may include a filament assembly 200 formed by a plurality of individual filaments 202 having a hexagonal cross-section as shown in FIG. 4, and may include a filament assembly 300 formed by a plurality of individual filaments 302 having a square cross-section as shown in FIG. 5. Additionally, the non-pneumatic tire 110 of FIG. 6 may include different non-stretch layers including filaments having different cross-sections or different alignments. For example, the first and third non-stretch layers may have a filament assembly formed by filaments having a hexagonal cross-section, and the second and fourth non-stretch layers may have a filament assembly formed by filaments having a square cross-section. As another example, the first and third non-stretch layers may Axial direction have a filament assembly formed by filaments having a central longitudinal axis that is aligned and radially offset with respect to adjacent filaments, and the second and fourth non-stretch layers may Axial directionIt may have a filament assembly formed by filaments having a central longitudinal axis offset and radially aligned with respect to adjacent filaments.

[0035] As used in this specification or the claims, the terms "includes" or "including" are intended to be inclusive in the same sense as the term "comprising" when used as a transitional phrase in a claim. Further, in the context in which the term "or" is used (e.g., A or B), it is intended to mean "A or B, or both." Where the Applicants intend to indicate "only A or B but not both," the term "only A or B but not both" is used. Thus, the use of the term "or" in this specification is inclusive and not exclusive. See Bryan A. Garner, A Dictionary of Modern Legal Usage 624 (2d Ed. 1995). Also, the terms "in" or "into" are intended to additionally mean "on" or "onto" as used in this specification or the claims. Further, the term "connect" as used in this specification or the claims is intended to mean not only "directly connected to" but also, as appropriate, "indirectly connected to" through another component.

[0036] Although this application has been illustrated by the description of its embodiments and those embodiments have been described in considerable detail, it is not the intention of the applicants to limit the scope of the appended claims to such detail or to any form of limitation. Additional advantages and improvements will be readily apparent to those skilled in the art. Accordingly, the application in its broader aspects is not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. For this reason, departures from such details may be made without departing from the spirit or scope of the general inventive concept of the applicant. For example, although a tread band has been described with respect to a non-pneumatic tire, it should be understood that the tread band can also be used in pneumatic tires such as run-flat pneumatic tires. As another example, the tread band has been described as including a filament assembly having individual filaments with hexagonal or square cross-sections, but the cross-sectional shape of the filaments may be any regular geometric shape having straight sides. Non-limiting examples of the cross-sectional shape of each filament include a triangle, a pentagon, a heptagon, or an octagon.

Claims

**Claim 1** A non-pneumatic tire, comprising: a lower ring having a first diameter; an upper ring having a second diameter larger than the first diameter and substantially coaxial with the lower ring; a support structure connecting the lower ring to the upper ring; a circumferential tread attached to the upper ring, the circumferential tread including a tread layer and a tread band, the tread band including a single filament assembly including a plurality of filaments having a non-circular cross-section, the filaments being configured and arranged to have a filling density of at least 92% within the filament assembly, and the single filament assembly constituting the entire tread band. **Claim 2** The non-pneumatic tire according to claim 1, wherein each of the plurality of filaments has a square cross-section. **Claim 3** The non-pneumatic tire according to claim 1, wherein each of the plurality of filaments has a central longitudinal axis, and the central longitudinal axis of the filament is aligned with respect to adjacent filaments in one of the axial direction and the radial direction of the non-pneumatic tire and offset with respect to adjacent filaments in the other of the axial direction and the radial direction of the non-pneumatic tire. **Claim 4** The non-pneumatic tire according to claim 1, wherein each of the plurality of filaments has a central longitudinal axis, and the central longitudinal axis of the filament is aligned with respect to adjacent filaments in both the axial direction and the radial direction of the non-pneumatic tire. **Claim 5** The non-pneumatic tire according to claim 1, wherein the plurality of filaments are fixed together using at least one of rubber, an adhesive, an epoxy, and a mechanical fastener.

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