WO2019244737A1 - Pneumatic tire - Google Patents

Abstract

A pneumatic tire 10 comprising a pair of bead cores 12A, a carcass 17, and a ring-shaped resin belt 20. The carcass 17 has: a carcass main body 18A straddling from one side of the pair of bead cores 12A to the other side; and a pair of folded back sections 18B that continue from the carcass main body 18A and fold back the bead cores 12A from inside to outside, in the tire width direction. The resin ring-shaped belt 20 has: a ring-shaped resin main body 20B arranged on the outside in of the carcass 17 in the tire radial direction and formed using resin; a reinforced cord 20A that extends in the tire circumferential direction, lines up in the tire width direction, having intervals therebetween, and is embedded in the resin main body 20B; and a surface on the outside in the tire radial direction that is covered by the folded back section 18D.

Description

Pneumatic tire

The present invention relates to a pneumatic tire provided with a belt including a spirally wound cord.

As a pneumatic tire to be mounted on an automobile, two or more inclined belt plies configured to include a cord inclined with respect to the tire circumferential direction on the tire radial outside of the carcass, and the tire radial outside of the inclined belt ply. A structure including a belt composed of a plurality of layers including a reinforcing layer and the like arranged is generally used (for example, see Japanese Patent Application Laid-Open No. 2013-244930 (Patent Document 1)).

Since the pneumatic tire of Patent Literature 1 includes two or more inclined belt plies and a reinforcing layer, it is possible to secure in-plane shear rigidity and the like necessary for reinforcing the crown portion of the carcass. Since the number of plies and reinforcing layers is large, it is difficult to reduce the weight of the tire.

In recent years, the need for weight reduction of pneumatic tires and the like has been increasing, and pneumatic tires corresponding thereto have been demanded. However, it is necessary to ensure the durability of the belt corresponding to the weight reduction.

Considering the above facts, an object of the present invention is to provide a pneumatic tire that can secure in-plane shear rigidity of a belt and maintain durability of the belt.

The pneumatic tire according to the first aspect of the present invention includes a pair of bead cores, a carcass main body extending from one of the pair of bead cores to the other, and a continuous carcass main body from the carcass main body. A carcass having a pair of folded portions folded from the inside to the outside of the carcass, an annular resin body formed of resin disposed outside the carcass in the tire radial direction, and extending in the tire circumferential direction and in the tire width direction. And a resin annular belt having a reinforcing cord buried in the resin main body and spaced at an interval, and at least a part of the outer surface in the tire radial direction is covered by the folded portion.

In the pneumatic tire of the first aspect, a resin annular belt having a resin body and a reinforcing cord embedded in the resin body is provided outside the carcass in the tire radial direction. In the resin annular belt, the reinforcing cords extend in the tire circumferential direction and are arranged at intervals in the tire width direction.

Thus, by disposing the resin main body between the reinforcing cords, it is possible to obtain higher in-plane shear rigidity as compared with a case where rubber is disposed between the reinforcing cords.

Also, since the outer surface of the resin annular belt in the tire radial direction is covered with the folded portion of the carcass, the resin annular belt can be protected, and the durability of the resin annular belt can be improved.

In the pneumatic tire according to the second aspect, each end of the pair of folded portions has an overlapping portion that is overlapped in the tire radial direction on the outer side in the tire radial direction of the resin annular belt.

According to the pneumatic tire of the second aspect, the entire surface of the resin annular belt in the tire radial direction outside can be covered, and the durability of the resin annular belt can be improved.

In the pneumatic tire according to a third aspect, the overlapping portion is disposed at a position covering the tire equatorial plane of the resin annular belt.

According to the pneumatic tire of the third aspect, the strength of the central portion in the tire width direction can be increased by the overlapping portion.

In the pneumatic tire according to a fourth aspect, each end of the pair of folded portions has an abutting portion that abuts on the outer side in the tire radial direction of the resin annular belt.

According to the pneumatic tire of the fourth aspect, the entire outer surface of the resin annular belt in the tire radial direction can be covered, and the durability of the resin annular belt can be improved.

As described above, according to the pneumatic tire of the present invention, it is possible to secure the in-plane shear rigidity of the belt and maintain the durability of the belt.

FIG. 2 is a partial cross-sectional view along a tire rotation axis of the pneumatic tire according to the present embodiment. It is a partial section perspective view along the tire rotation axis of the pneumatic tire concerning this embodiment. FIG. 2 is a partially enlarged view of FIG. 1. It is a fragmentary sectional view along the tire rotation axis of the pneumatic tire concerning a modification of this embodiment. FIG. 10 is a partial cross-sectional view along a tire rotation axis of a pneumatic tire according to another modification of the present embodiment. FIG. 10 is a partial cross-sectional view along a tire rotation axis of a pneumatic tire according to another modification of the present embodiment.

FIG. 1 shows a pneumatic tire 10 according to an embodiment of the present invention. The pneumatic tire 10 shows a radial tire as an example. In the drawings, arrow W indicates the tire width direction, and arrow R indicates the tire radial direction. Here, the tire width direction refers to a direction parallel to the rotation axis of the pneumatic tire 10. The tire radial direction refers to a direction orthogonal to the rotation axis of the pneumatic tire 10. Reference symbol CL indicates the equatorial plane of the pneumatic tire 10 (tire equatorial plane).

In the present embodiment, the grounding end E of the tread 30 and the grounding width TW, which will be described later, mean that the pneumatic tire 10 is mounted on a standard rim specified in JATMA YEAR BOOK (2018 edition, Japan Automobile Tire Association Standard). Then, it is filled with 100% internal pressure of the air pressure (maximum air pressure) corresponding to the maximum load capacity (bold load in the internal pressure-load capacity correspondence table) in the applicable size ply rating in JATMA YEAR BOOK, This is one in which the rotation axis is arranged parallel to the flat plate and a mass corresponding to the maximum load capacity is added. When the TRA standard and the ETRTO standard are applied at the place of use or the place of manufacture, the respective standards are followed.

As shown in FIG. 1, the pneumatic tire 10 includes a pair of bead portions 12 in which a bead core 12 </ b> A is embedded, a pair of side portions 14 extending from the pair of bead portions 12 outward in the tire radial direction, and a tire from the side portion 14. A crown portion 16 extending inward in the width direction. A carcass 17 composed of one carcass ply 18 straddles between one bead portion 12 and the other bead portion 12. A resin annular belt 20 is provided on the crown portion 16 on the outer side in the tire radial direction of the carcass 17. A tread 30 is disposed outside the resin annular belt 20 in the tire radial direction. A plurality of main grooves 32 are formed in the tread 30 along the tire circumferential direction.

The carcass ply 18 is formed by covering a plurality of cords 18A (see FIG. 2) extending in the radial direction of the pneumatic tire 10 with a coating rubber 18B (see FIG. 2). The cord material of the carcass ply 18 is, for example, PET, but may be another known material.

The end portion of the carcass ply 18 in the tire width direction is bent outward in the tire radial direction by the bead core 12A. In the carcass ply 18, a portion extending from one bead core 12A to the other bead core 12A is called a main body portion 18C, and a portion that is folded back from the bead core 12A is called a folded portion 18D.

Bead filler 12B whose thickness gradually decreases from the bead core 12A toward the tire radially outer side is disposed between the main body portion 18C of the carcass ply 18 and the folded portion 18D.

An inner liner 26 made of rubber is arranged inside the carcass 17 in the tire, and a side rubber layer 24 made of rubber material is arranged outside the carcass 17 in the tire width direction.

The folded portion 18 </ b> D of the carcass ply 18 extends to the resin annular belt 20, which will be described later, and covers the outer surface of the resin annular belt 20 in the tire radial direction. The details of the turning portion 18D will be described later.

As shown in FIGS. 2 and 3, the resin annular belt 20 includes a reinforcing cord 20A spirally wound in the tire circumferential direction, and a resin main body 20B of a resin material covering the reinforcing cord 20A. . The resin annular belt 20 can be formed of a ring-shaped hoop in which a resin-coated cord 20C in which a reinforcing cord 20A is coated with a resin main body 20B is spirally wound and integrated.

In the present embodiment, one resin-coated cord 20C is spirally wound in the tire circumferential direction to form the resin annular belt 20, but a reinforcing cord 20A extending along the tire circumferential direction in another configuration is used. It may be embedded in the resin body 20B. For example, the resin-coated cord 20C may be formed in a ring shape, and a plurality of ring-shaped resin-coated cords 20C may be formed side by side in the tire width direction.

The resin body 20B is made of a resin material having a higher tensile modulus than the rubber material forming the side rubber layer 24 and the rubber material forming the tread 30 described later. The tensile modulus (defined in JIS K7113: 1995) of the resin main body 20B is preferably 50 MPa or more. The upper limit of the tensile modulus of the resin main body 20B is preferably set to 1000 MPa or less. The tensile modulus of the resin body 20B is particularly preferably in the range of 200 to 500 MPa.

Examples of the material of the resin body 20B include general-purpose resins such as thermoplastic resins, thermoplastic elastomers, thermosetting resins, and (meth) acrylic resins, EVA resins, vinyl chloride resins, fluorine resins, and silicone resins. In addition, engineering plastics (including super engineering plastics) and the like can be used. The resin material here does not include vulcanized rubber.

A thermoplastic resin (including a thermoplastic elastomer) refers to a polymer compound in which a material softens and flows with an increase in temperature and becomes relatively hard and strong when cooled. In the present specification, among these materials, the material softens and flows with an increase in temperature, becomes a relatively hard and strong state when cooled, and a polymer compound having rubber-like elasticity is made into a thermoplastic elastomer, and the material with the increase in temperature becomes a material. Softens, flows, and becomes relatively hard and strong when cooled, and distinguishes a polymer compound having no rubber-like elasticity as a non-elastomer thermoplastic resin.

Examples of thermoplastic resins (including thermoplastic elastomers) include polyolefin-based thermoplastic elastomer (TPO), polystyrene-based thermoplastic elastomer (TPS), polyamide-based thermoplastic elastomer (TPA), polyurethane-based thermoplastic elastomer (TPU), and polyester Thermoplastic elastomer (TPC), dynamically crosslinked thermoplastic elastomer (TPV), polyolefin thermoplastic resin, polystyrene thermoplastic resin, polyamide thermoplastic resin, polyester thermoplastic resin, etc. No.

Thermosetting resin refers to a polymer compound that forms a three-dimensional network structure with a rise in temperature and cures, and examples thereof include a phenol resin, an epoxy resin, a melamine resin, and a urea resin.

補強 Further, it is preferable to use a reinforcing cord 20A that is thicker than the cord 18A of the carcass ply 18 and has a large strength (tensile strength). The reinforcing cord 20A can be composed of a monofilament (single wire) such as a metal fiber or an organic fiber, or a multifilament (stranded wire) obtained by twisting these fibers. The reinforcing cord 20A of the present embodiment is a steel cord. As the reinforcing cord 20A, for example, a “1 × 5” steel cord having a diameter of 0.225 mm can be used, but a steel cord having another conventionally known structure can also be used.

幅 The width BW of the resin annular belt 20 is preferably 75% or more and 110% or less with respect to the contact width TW (distance between the contact ends E) of the tread 30 measured along the tire axial direction.

The end 18E of each folded portion 18D of the carcass ply 18 straddles the tire equatorial plane CL, and has an overlapping portion 19 in which the folded portions 18D overlap in the tire radial direction. In the folded portion 18D of the carcass ply 18, a portion laminated on the outer side in the tire radial direction of the resin annular belt 20 is referred to as a folded protection portion 18F. The overlapping portion 19 covers the tire equatorial plane CL of the resin annular belt 20. The overlapping portion 19 is disposed at a position overlapping the main groove 32 at a position close to the tire equatorial plane CL in the tire radial direction.

The overlapping portion 19 preferably covers at least １ ／ of the belt width BW of the resin annular belt 20 straddling the tire equatorial plane CL, that is, covers each BW / 6 on both sides in the tire width direction from the tire equatorial plane CL.

(Action, effect)
Next, the operation and effect of the pneumatic tire 10 of the present embodiment will be described.

ク ラ ウ ン In the pneumatic tire 10 of the present embodiment, the crown portion 16 of the carcass 17 is reinforced by the resin annular belt 20. Therefore, higher in-plane shear stiffness can be obtained as compared with the case where the rubber is reinforced by the belt in which the rubber is disposed between the reinforcing cords. By securing the in-plane shear rigidity of the resin annular belt 20, lateral force when a slip angle is given to the pneumatic tire 10 can be sufficiently generated, and steering stability can be secured. Also, the responsiveness can be improved.

Further, the out-of-plane bending rigidity is secured by the resin annular belt 20, and when a large lateral force is input to the pneumatic tire 10, the buckling of the tread 30 (the surface of the tread 30 undulates and a part of the tread 30 is separated from the road surface) Phenomenon).

Further, in the present embodiment, the cord 18A is formed in the tire width direction in the folding protection portion 18F of the folded portion 18D in which the outer surface of the resin annular belt 20 in the tire radial direction is covered with the folded portion 18D of the carcass ply 18. Since they are arranged, the resin annular belt 20 can be protected, and in particular, the development of cracks in the tire circumferential direction can be suppressed.

In addition, in the present embodiment, since the turn-back protection portion 18F covers the entire surface of the resin annular belt 20 on the outer side in the tire radial direction, the effect of suppressing the occurrence of cracks in the resin annular belt 20 can be enhanced.

Further, in the present embodiment, since the overlapping portion 19 is disposed at a position corresponding to the center in the tire width direction across the tire equatorial plane CL of the resin annular belt 20, the center of the pneumatic tire 10 in the tire width direction is provided. The strength of the part can be increased. Thereby, the durability in the plunger test can be improved.

In the present embodiment, the overlapping portion 19 is formed at a position corresponding to the central portion in the tire width direction across the tire equatorial plane CL of the resin annular belt 20, but the overlapping portion 19 is formed at another portion. Alternatively, the end 18E of the folded portion 18D may be arranged. As shown in FIG. 4, the end 18 </ b> E is located at the outer end in the tire width direction of the resin annular belt 20 so that the overlapping portion 19 is arranged corresponding to the entire surface of the resin annular belt 20 in the tire radial direction. It may be arranged.

Moreover, the overlapping portion 19 is not essential, and as shown in FIG. 5, the ends 18E of the folded portions 18D may be joined to each other. According to this configuration, since there is no overlapping portion 19, the thickness in the tire width direction is made uniform, and the weight of the pneumatic tire 10 can be reduced.

折 Folding protection portion 18F does not necessarily need to cover the entire surface of resin annular belt 20 outside in the tire radial direction, and may cover only the outside in the tire width direction as shown in FIG. In this case, assuming that the belt half width BW / 2 is from the tire equatorial plane CL of the resin annular belt 20 to the outer end in the tire radial direction, each folding protection portion 18F is at least the belt half width BW / 2 of the resin annular belt 20. It is preferable to cover a range of 1/3 (BW / 6) outside in the tire width direction.

The disclosure of Japanese Patent Application No. 2018-115415 filed on June 18, 2018 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards mentioned herein are to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference. Incorporated herein by reference.

Claims (4)

A pair of bead cores,
A carcass body portion extending from one of the pair of bead cores to the other, and a carcass having a pair of folded portions that are continuous from the carcass body portion and that fold the bead core from inside to outside in the tire width direction.
An annular resin body formed of resin and disposed outside the carcass in the tire radial direction, and a reinforcing cord extending in the tire circumferential direction and arranged at intervals in the tire width direction and embedded in the resin body. And a resin annular belt in which at least a part of the outer surface in the tire radial direction is covered with the folded portion,
Pneumatic tire with. The pneumatic tire according to claim 1, wherein each end of the pair of folded portions has an overlapping portion that is overlapped in the tire radial direction outside the resin annular belt in the tire radial direction. The pneumatic tire according to claim 2, wherein the overlapping portion is arranged at a position covering a tire equatorial plane of the resin annular belt. 2. The pneumatic tire according to claim 1, wherein each end of the pair of folded portions has an abutting portion that abuts on the outer side in the tire radial direction of the resin annular belt. 3.

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