JP2019217998A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire which can prevent malfunction due to cracking of a circumferential belt.SOLUTION: A pneumatic tire has a circumferential belt including a cord in a spirally wound state and a coated resin coating the cord provided on a tread part, and includes a detection part which can detect cracking of the circumferential belt.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire.

  2. Description of the Related Art Conventionally, a technology has been developed that allows a vehicle to safely stop when a tire fails during traveling. For example, a run-flat tire is known that can safely travel a certain distance even when the internal pressure is reduced due to puncture or the like and can stop safely (see Patent Document 1).

JP 2017-144976 A

  However, it is desirable to avoid the failure of the tire itself during running.

  An object of the present invention is to provide a pneumatic tire that can prevent a failure due to a crack in a circumferential belt beforehand.

A pneumatic tire according to a first aspect of the present invention includes a cord in a spirally wound state, and a circumferential belt including a coating resin covering the cord in a tread portion. The tire is provided with a detection unit capable of detecting a crack in the circumferential belt.
With such a configuration, a failure due to a crack in the circumferential belt can be prevented beforehand.

A pneumatic tire according to one embodiment of the present invention includes a tread rubber that is located on the outer side in the tire radial direction of the circumferential belt and has a groove formed on an outer surface of a tread, and a groove of the groove of the tread rubber. At the bottom, there is formed a depression or cutout in which the thickness in the tire radial direction up to the outer surface in the tire radial direction of the circumferential belt is smaller than the position of the groove around the groove bottom. Is constituted by a thin portion of the tread rubber, which is a portion from the concave portion or the cut portion of the groove bottom of the groove portion to the outer surface of the circumferential belt in the tire radial direction.
With such a configuration, it is possible to easily notify the outside of the tire of a crack in the circumferential belt that may cause a failure of the tire.

As one embodiment of the present invention, the thin portion of the tread rubber includes a skin portion including the recessed portion or the cut portion at the groove bottom of the groove portion, and is located inside a tire radial direction of the skin portion. , The skin portion includes an identification portion that can be visually identified.
With such a configuration, it is possible to more easily identify a state in which the thin portion has a crack.

As one embodiment of the present invention, the skin portion is formed of a rubber material different from the identification portion.
With such a configuration, when the circumferential belt is cracked, a crack is easily formed in the skin portion, and a configuration in which the identification portion can be visually recognized earlier from the outer surface of the tread can be realized.

As one embodiment of the present invention, among the groove walls of the groove portion, the specific groove wall of the portion where the recessed portion or the cut portion is formed is, in a plan view of the tread outer surface, the specific groove of the groove portion. It has an outer shape that is distinguishable from a peripheral groove wall located around the wall.
With this configuration, the discriminating power of the thin portion from the outside can be enhanced.

The pneumatic tire as one embodiment of the present invention is joined to the circumferential belt, and intersects with the cord in a spirally wound state at a plurality of points when viewed from the tread outer surface side. And an RFID tag provided with an antenna extending over at least a part of the area in the tire width direction, and the detection unit is configured by the RFID tag.
With such a configuration, it is possible to easily notify the outside of the tire of a crack in the circumferential belt that may cause a failure of the tire.

As one embodiment of the present invention, the antenna of the RFID tag has a direction inclining at an inclination of 10 ° or more with respect to the extending direction of the cord of the circumferential belt when viewed from the outer surface side of the tread. And extends linearly.
With such a configuration, the antenna of the RFID tag easily intersects the spirally wound cord.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which can prevent the failure based on the crack of a circumferential belt beforehand can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing in the cross section parallel to a tire width direction of the tire as one Embodiment of this invention. FIG. 2 is a development view showing a tread outer surface of the tire shown in FIG. 1. It is II sectional drawing of FIG. FIG. 3 is a sectional view taken along line II-II of FIG. 2. FIG. 4 is a view showing a state in which the thin portion shown in FIG. 3 is torn following a crack in the circumferential belt. It is a figure which shows the modification of the circumferential groove and the width direction groove shown in FIG. It is a figure which shows the circumferential belt and detection part of the tire as another embodiment different from the tire shown in FIG. FIG. 8 is a diagram illustrating a case where a crack occurs in a portion of the coating resin of the circumferential belt illustrated in FIG. 7 that is covered by an antenna of the RFID tag.

  Hereinafter, embodiments of a pneumatic tire according to the present invention will be described with reference to the drawings. In the drawings, common members / parts are denoted by the same reference numerals.

  Hereinafter, unless otherwise specified, dimensions, length relations, positional relations, etc. of each element are measured in a reference state where a pneumatic tire is mounted on an applicable rim, a specified internal pressure is filled, and no load is applied. And

  Here, the “applicable rim” is an industrial standard effective in a region where a pneumatic tire is produced and used. In Japan, JATMA (Japan Automobile Tire Association) JATMA YEAR BOOK, and in Europe, ETRTO (The European). STANDARDS MANUAL of Tire and Rim Technical Organization, U.S.A. standard rim (ETRTOS MANDAL of ETRTDS NANDAL) in the applicable size described in YEAR BOOK of the TIRE and Rim Association, Inc. (TRA) in the United States or described in the future, etc. Indicates the measuring rim, and Design rim in the case of TRA's YEAR BOOK. In addition, a size that may be included in the above-mentioned industry standard in the future may be included.Examples of the “size to be described in the future” include a size described as “FUTURE DEVELOPMENTS” in the ETRTO 2013 edition. ) Is a rim having a width corresponding to the bead width of the pneumatic tire when the size is not described in the above industrial standards.

    The "prescribed internal pressure" refers to an air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel in an applicable size / prirating described in JATMA YEAR BOOK or the like, and described in the above-mentioned industrial standard. In the case of no size, it refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for each vehicle on which the tire is mounted. In addition, the “maximum load” described later is defined for each tire to which the tire is mounted in the case of a tire having a maximum load capacity of a standard such as JATMA in a tire of an applicable size or a size not described in the above industrial standard. It means the load corresponding to the maximum load capacity.

<First embodiment>
FIG. 1 is a diagram illustrating a pneumatic tire 1 (hereinafter simply referred to as “tire 1”) as the present embodiment. FIG. 1 is a cross-sectional view of the tire 1 in a cross section parallel to the tire width direction A. Hereinafter, this cross section is referred to as “cross section in the tire width direction”. Note that the tire 1 of the present embodiment has a configuration symmetrical with respect to the tire equatorial plane CL, but may have a configuration asymmetrical with respect to the tire equatorial plane CL.

  As shown in FIG. 1, the tire 1 has a tread portion 1a, a pair of sidewall portions 1b extending inward in the tire radial direction B from both ends of the tread portion 1a in the tire width direction A, and each sidewall portion 1b. And a pair of beads 1c provided at the inner end in the tire radial direction B. The tire 1 of the present embodiment is a tubeless type radial tire for a passenger car. Here, the “tread portion 1a” means a portion sandwiched between the tread ends TE on both sides in the tire width direction A. The “bead portion 1c” means a portion where a bead member 3 described later is located in the tire radial direction B. The “sidewall portion 1b” means a portion between the tread portion 1a and the bead portion 1c. The “tread end TE” refers to the outermost position in the tire width direction of the ground contact surface in a state where the tire is mounted on the applicable rim, the specified internal pressure is filled, and the maximum load is applied. .

  The tire 1 includes a bead member 3, a carcass 4, a resin ring 5, a circumferential belt 6, a tread rubber 7, a side rubber 8, and an inner liner 9.

[Bead member 3]
The bead member 3 is embedded in the bead portion 1c. The bead member 3 includes a bead core 3a and a rubber bead filler 3b located outside the bead core 3a in the tire radial direction B. The bead core 3a has a plurality of bead wires whose periphery is covered with rubber. The bead wire is formed by a steel cord. The steel cord may, for example, consist of a steel monofilament or stranded wire.

[Carcass 4]
The carcass 4 extends between the pair of bead portions 1c, more specifically, between the bead cores 3a of the pair of bead members 3, and extends in a toroidal shape. The carcass 4 has at least a radial structure.

  Further, the carcass 4 includes one or more (one in the present embodiment) carcass plies 4a in which carcass cords are arranged at an angle of, for example, 75 ° to 90 ° with respect to the tire circumferential direction C (see FIG. 1 and the like). Have been. The carcass ply 4a includes a ply body portion located between the pair of bead cores 3a, and a ply fold portion that is folded at both ends of the ply body portion around the bead core 3a from inside to outside in the tire width direction A. ing. Further, a bead filler 3b extending from the bead core 3a to the outside in the tire radial direction B is disposed between the ply body portion and the ply turn-back portion. As the carcass cord constituting the carcass ply 4a, a polyester cord is employed in the present embodiment, but other than this, an organic fiber cord such as nylon, rayon, aramid or a metal cord such as steel is employed as necessary. Is also good. Also, the number of carcass plies 4a may be two or more.

[Resin ring 5]
The resin ring 5 is disposed on the tread portion 1a. In addition, the resin annular body 5 of the present embodiment includes reduced diameter portions 13 and 14 whose outer diameters decrease toward the outer end in the tire width direction A at both ends in the tire width direction A. Specifically, the outer surface of the resin annular body 5 in the tire radial direction B of the present embodiment has a barrel shape, and not only the ends in the tire width direction A but also all the sides in the tire width direction A sandwiching the tire equatorial plane CL. , And reduced diameter portions 13 and 14. However, the reduced diameter portions 13 and 14 may be a resin ring provided only at the end in the tire width direction A. Further, a cylindrical resin annular body having no outer diameter and inner diameter regardless of the position in the tire width direction A without the reduced diameter portions 13 and 14 may be used. As described above, a configuration in which the reduced diameter portions 13 and 14 are provided is preferable. By using the resin annular body 5 including the reduced diameter portions 13 and 14, it is possible to suppress the ground pressure from being locally increased near the tread end TE, and to suppress uneven wear of the outer surface of the tread. In addition, the tire width direction A of the resin annular body 5 extends beyond the tread end TE to the outside in the tire width direction A.

  Note that the end of the resin annular body 5 in the tire width direction A means a portion in the tire width direction A that is separated from the tire equatorial plane CL by more than １ ／ of the tire contact width W. On the other hand, the central portion of the resin annular body 5 in the tire width direction A means a portion within a distance of 1/4 of the tire contact width W from the tire equatorial plane CL in the tire width direction A. Here, the “tire contact width” is a distance in the tire width direction between the tread ends TE in a state where the tire is mounted on the above-described applicable rim, filled with a specified internal pressure, and is in a no-load state.

  As the resin constituting the resin annular body 5, for example, a thermoplastic elastomer or a thermoplastic resin can be used, and a resin that is cross-linked by heat or an electron beam or a resin that is cured by thermal rearrangement can also be used. Note that the resin constituting the resin ring 5 does not include rubber (an organic polymer substance exhibiting rubber elasticity at room temperature).

  Examples of the thermoplastic elastomer include polyolefin-based thermoplastic elastomer (TPO), polystyrene-based thermoplastic elastomer (TPS), polyamide-based thermoplastic elastomer (TPA), polyurethane-based thermoplastic elastomer (TPU), and polyester-based thermoplastic elastomer (TPC). And dynamically crosslinked thermoplastic elastomers (TPV). Further, examples of the thermoplastic resin include a polyurethane resin, a polyolefin resin, a vinyl chloride resin, and a polyamide resin. Further, as the thermoplastic resin, for example, the deflection temperature under load (under a load of 0.45 MPa) specified in ISO75-2 or ASTM D648 is 78 ° C. or more, and the tensile yield strength specified in JIS K7113 is used. Those having a tensile elongation at break of at least 10 MPa, a tensile elongation at break also specified by JIS K7113, and a Vicat softening temperature (Method A) of 130 ° C. or more specified by JIS K7206 can be used. Particularly preferred are TPA, TPC, TPV, polyamide resin, polyester resin and blends thereof.

  The elastic modulus of the resin ring 5 can be set in the range of 100 MPa to 1000 MPa, more preferably in the range of 200 MPa to 700 MPa. Note that the elastic modulus of the resin annular body 5 means a tensile elastic modulus. The measurement of the tensile modulus is performed according to JIS K7113: 1995. Specifically, the tensile elasticity is measured at a tensile speed of 100 mm / min using Shimadzu Autograph AGS-J (5KN) manufactured by Shimadzu Corporation. When measuring the tensile modulus of the resin ring, the measurement data may be adjusted by punching out the resin ring, or, for example, a measurement sample of the same material as the resin ring is separately prepared and the elastic modulus is measured. You may.

  In the tire width direction A, the resin annular body 5 of the present embodiment extends to the outside of a circumferential belt 6 described later. Further, the resin annular body 5 of the present embodiment is located inside the circumferential belt 6 in the tire radial direction B. Further, unlike the circumferential belt 6, the resin annular body 5 does not include a cord. That is, no cord is arranged in the resin annular body 5.

  The thickness of the resin ring 5 is set in the range of 0.1 mm to 3 mm.

[Circumferential belt 6]
The circumferential belt 6 is disposed outside the resin annular body 5 in the tire radial direction B in the tread portion 1a. The circumferential belt 6 includes a cord 10b and a coating resin 10a that covers the cord 10b. Specifically, the circumferential belt 6 of the present embodiment has at least one layer (one in the present embodiment) disposed outside the crown portion of the carcass 4 and the resin annular body 5 in the tire radial direction B. Layer). More specifically, as shown in FIG. 1, the circumferential belt 6 of the present embodiment includes only one circumferential belt layer.

  In the circumferential belt 6 of the present embodiment, a steel cord as a metal belt cord is formed along the tire circumferential direction C (see FIG. 1 and the like) (10 ° or less, preferably 5 ° or less with respect to the tire circumferential direction C, (Preferably at an angle of 2 ° or less), a spiral belt formed in a state of being spirally wound around a tire central axis. More specifically, the circumferential belt 6 of the present embodiment is formed of a resin-coated cord 10 made of a cord 10b such as a steel cord covered with a coating resin 10a. That is, the circumferential belt 6 is spirally wound around the outer surface of the resin annular body 5 in the tire radial direction B, between the reduced diameter portions 13 and 14 at both ends of the resin annular body 5 in the tire width direction A. It is constituted by the resin-coated cord 10 in a turned state.

  The resin-coated cord 10 is wound around the outer surface of the resin annular body 5 in the tire radial direction B while being joined to the outer surface of the resin annular body 5 in the tire radial direction B. In the present embodiment, the resin coating cord 10 and the resin ring 5 are joined by welding the coating resin 10 a of the resin coating cord 10 and the resin ring 5. However, the coating resin 10a of the resin-coated cord 10 and the resin annular body 5 are not limited to welding, and may be joined by bonding with an adhesive or the like.

  In the resin-coated cord 10 of the present embodiment, portions adjacent to each other in the tire width direction A are joined. In the present embodiment, portions of the resin-coated cord 10 adjacent to each other in the tire width direction A are joined by welding the coating resins 10a. However, the portions of the resin-coated cord 10 adjacent to each other in the tire width direction A are not limited to welding, but may be joined by bonding with an adhesive or the like.

  In the tire width direction A, portions adjacent to each other in the tire width direction A of the resin-coated cord 10 spirally wound around the resin ring body 5 are at least positioned at the reduced diameter portions 13 and 14 of the resin ring body 5 in the tire width direction A. It is preferable to adopt a configuration in which they are joined. As described above, the diameter-reduced portions 13 and 14 of the resin annular body 5 are liable to be concentrated by the ground pressure and are easily broken. Therefore, by joining the portions of the resin-coated cord 10 adjacent to each other in the tire width direction A, the ground pressure can be distributed to a wider range of the resin annular body 5 through the circumferential belt 6. As a result, concentration of strain on the reduced diameter portions 13 and 14 of the resin annular body 5 can be suppressed, and the durability of the resin annular body 5 can be improved.

  In the present embodiment, adjacent portions in the tire width direction A of the resin-coated cord 10 spirally wound around the resin ring 5 are the reduced diameter portions 13 of the resin ring 5 in the tire width direction A. Not only at the position 14 but also in the entire area in the tire width direction A.

  The circumferential belt 6 of the present embodiment has a substantially constant thickness regardless of the position in the tire width direction A. The thickness of the circumferential belt 6 of the present embodiment can be set, for example, in the range of 1.5 mm to 7 mm, more preferably in the range of 2 mm to 5 mm. Further, the elastic modulus of the coating resin 10a of the circumferential belt 6 can be set in a range of 100 MPa to 1000 MPa, more preferably in a range of 200 MPa to 700 MPa. The measurement of the tensile modulus is performed according to JIS K7113: 1995. Specifically, the tensile elasticity is measured at a tensile speed of 100 mm / min using Shimadzu Autograph AGS-J (5KN) manufactured by Shimadzu Corporation. When measuring the tensile modulus of the coating resin, the measurement data may be adjusted by punching out the coating resin if possible.For example, a measurement sample of the same material as the coating resin is separately prepared and the elastic modulus is measured. You may.

  As shown in FIG. 1, the resin-coated cord 10 of the present embodiment includes two steel cords, but may be a resin-coated cord including only one steel cord, and may include a resin including three or more steel cords. It may be a coated cord.

  As the cord 10b, any known material can be used, for example, the above-described steel cord can be used. The steel cord may, for example, consist of a steel monofilament or stranded wire. Further, the cord 10b may be made of an organic fiber, a carbon fiber, or a stranded wire thereof.

  Further, as the coating resin 10a, for example, a thermoplastic elastomer or a thermoplastic resin can be used, and a resin that is cross-linked by heat or an electron beam or a resin that is cured by thermal rearrangement can also be used. Examples of the thermoplastic elastomer include polyolefin-based thermoplastic elastomer (TPO), polystyrene-based thermoplastic elastomer (TPS), polyamide-based thermoplastic elastomer (TPA), polyurethane-based thermoplastic elastomer (TPU), and polyester-based thermoplastic elastomer (TPC). And dynamically crosslinked thermoplastic elastomers (TPV). Further, examples of the thermoplastic resin include a polyurethane resin, a polyolefin resin, a vinyl chloride resin, and a polyamide resin. Further, as the thermoplastic resin, for example, the deflection temperature under load (under a load of 0.45 MPa) specified in ISO75-2 or ASTM D648 is 78 ° C. or more, and the tensile yield strength specified in JIS K7113 is used. Those having a tensile elongation at break of at least 10 MPa, a tensile elongation at break also specified by JIS K7113, and a Vicat softening temperature (Method A) of 130 ° C. or more specified by JIS K7206 can be used. The tensile modulus (defined by JIS K7113: 1995) of the coating resin 10a that covers the cord 10b is preferably 50 MPa or more. Further, the tensile modulus of the coating resin 10a for coating the cord 10b is preferably 1000 MPa or less. It is assumed that the coating resin 10a does not include rubber (an organic polymer substance exhibiting rubber elasticity at normal temperature).

[Tread rubber 7 and side rubber 8]
The tread rubber 7 forms an outer surface of the tread portion 1a in the tire radial direction B (hereinafter, referred to as “tread outer surface”), and the tread outer surface of the present embodiment has a tire circumferential direction C (FIG. 1 and the like, and a groove portion 20 such as a circumferential groove 7a extending in the tire width direction A and a width direction groove not shown in FIG. 1 (see “width direction groove 7b” in FIG. 2). Have been. That is, the tread pattern including the groove 20 is formed on the outer surface of the tread of the present embodiment. The details of the groove 20 will be described later (see FIG. 2 and the like). The side rubber 8 forms an outer surface of the sidewall portion 1b in the tire width direction A, and is formed integrally with the tread rubber 7 described above.

[Inner liner 9]
The inner liner 9 is laminated on the inner surface of the carcass 4, and in the present embodiment, is formed of butyl rubber having low air permeability. The butyl rubber means butyl rubber and halogenated butyl rubber which is a derivative thereof.

  Next, the characteristic portion of the tire 1 will be described in more detail.

  FIG. 2 is a developed view showing an outer surface of the tread of the tire 1. As shown in FIG. 2, a plurality of grooves 20 are formed on the outer surface of the tread of the tire 1. Specifically, on the outer surface of the tread of the tire 1 of the present embodiment, a plurality of circumferential grooves 7a extending substantially parallel to the tire circumferential direction C and a land portion 15 located between the plurality of circumferential grooves 7a are provided. , Are provided. More specifically, four circumferential grooves 7a are formed on the outer surface of the tread of the tire 1 of the present embodiment. The four circumferential grooves 7a are formed at two symmetrical positions on both sides of the tire equatorial plane CL, and two center circumferential grooves 7a1 are located outside the center circumferential groove 7a1 in the tire width direction A. And two outer circumferential grooves 7a2 formed at symmetrical positions on both sides of the tire equatorial plane CL. Therefore, the land portion 15 of the present embodiment is located between the two central circumferential grooves 7a1, and intersects the tire equatorial plane CL, the central land portion 7a, the central circumferential groove 7a1, and the outer circumferential groove. 7a2, and an end land portion 15c located between the outer circumferential groove 7a2 and the tread end TE.

  As shown in FIG. 2, a width direction groove 7 b extending in the tire width direction A is formed in the end land portion 15 c on the outer surface of the tread of the tire 1.

  Thus, on the outer surface of the tread of the tire 1 of the present embodiment, the circumferential groove 7a and the width groove 7b as the groove 20 are formed. However, the groove 20 is not limited to the circumferential groove 7a and the width groove 7b of the present embodiment, but may have another arrangement and shape.

  FIG. 3 is a sectional view showing an II section of FIG. FIG. 4 is a cross-sectional view showing a II-II cross section of FIG.

  As shown in FIGS. 3 and 4, the groove bottom 42 of the circumferential groove 7 a as the groove 20 of the tread rubber 7 and the groove bottom 44 of the width direction groove 7 b extend to the outer surface of the circumferential belt 6 in the tire radial direction B. The tire is formed with a recessed portion or a cutout in which the thickness in the tire radial direction is smaller than the position around the groove bottom.

  Specifically, as shown in FIG. 3, the tire bottom in the tire radial direction B up to the outer surface in the tire radial direction B of the circumferential belt 6 is provided on the groove bottom 42 of the circumferential groove 7 a as the groove 20. The recess 30a is formed smaller than the surrounding position, that is, further recessed from the surrounding position.

  As shown in FIG. 2, the recess 30 a is formed in the tire width direction region including the center position in the tire width direction A among the groove bottoms 42 of the circumferential groove 7 a as the groove 20. May be formed at a position deviated to one side in the tire width direction A.

  As shown in FIG. 3, the circumferential groove 7 a of the present embodiment is continuous with the groove wall 41 extending in the tire radial direction B and the groove walls 41 on both sides in the tire width direction cross-sectional view, and And a groove bottom 42 extending in the direction A. In other words, the circumferential groove 7a shown in FIG. 3 has a substantially rectangular cross section when viewed in the cross section in the tire width direction. The recessed portion 30a of the present embodiment includes a portion in the tire width direction A and a portion in the tire circumferential direction C among the groove bottoms 42 of the circumferential groove 7a extending over the entire region in the tire circumferential direction C. It is formed by depressing inward in the tire radial direction B. The concave portion 30a of the present embodiment has a configuration having a substantially rectangular cross section in a tire width direction cross sectional view, but is not limited to this cross sectional shape. For example, in the same cross sectional view, a V shape or a U shape cross section may be used. May be provided. Further, the circumferential groove 7a of the present embodiment also has a substantially rectangular cross-section due to the groove wall 41 and the groove bottom 42 when viewed in a cross section in the tire width direction, but is not limited to this cross-sectional shape. In cross-sectional view, a configuration having a U-shaped cross section or a trapezoidal cross section may be employed.

  By providing the above-mentioned depression 30a on the groove bottom 42 of the circumferential groove 7a as the groove 20, the outer surface of the circumferential belt 6 in the tire radial direction from the depression 30a of the groove bottom 42 of the circumferential groove 7a as the groove 20 The thin portion 50a, which is the portion up to this point, can be formed. The thin portion 50a is thinner than the portion of the groove bottom 42 where the recess 30a is not formed to the outer surface of the circumferential belt 6 in the tire radial direction. The thin portion 50a of the present embodiment constitutes a detection unit that can detect a crack in the circumferential belt 6. The details will be described later (see FIG. 5).

  As shown in FIG. 4, in the groove bottom 44 of the width direction groove 7 b as the groove 20, the tire radial thickness up to the outer surface of the circumferential belt 6 in the tire radial direction B is equal to the circumference of the groove bottom 44. A recess 30b that is smaller than the position, that is, further recessed than the surrounding position, is formed.

  As shown in FIG. 2, the recess 30 b is formed in the tire width direction region including the center position in the tire width direction A among the groove bottoms 44 of the width direction grooves 7 b as the groove portions 20. May be formed at a position deviated to one side in the tire width direction A. Further, as shown in FIG. 2, the depression 30b is formed in the tire circumferential direction area including the center position in the tire circumferential direction C in the groove bottom 44 of the width direction groove 7b as the groove 20. The bottom 44 may be formed at a position deviated to one side in the tire circumferential direction C.

  Further, the width direction groove 7b of the present embodiment is continuous with the groove wall 43 extending in the tire radial direction B and the groove walls 43 on both sides in a cross-sectional view orthogonal to the tire width direction A and in the tire circumferential direction C. And a groove bottom 44 extending. In other words, the width direction groove 7b of the present embodiment has a substantially rectangular cross section in a cross section orthogonal to the tire width direction A. The recess 30b of the present embodiment is formed by recessing a part of the groove bottom 44 of the width direction groove 7b in the tire circumferential direction C and a part in the tire width direction A inside the tire radial direction B. ing. The concave portion 30b of the present embodiment has a configuration having a substantially rectangular cross-section in a tire width direction cross-sectional view (see FIG. 4), but is not limited to this cross-sectional shape. A configuration having a U-shaped cross section may be used.

  By providing the above-mentioned depression 30b in the groove bottom 44 of the width direction groove 7b as the groove 20, the outer surface of the circumferential belt 6 in the tire radial direction from the depression 30b of the groove bottom 44 of the width direction groove 7b as the groove 20 The thin portion 50b, which is the portion up to this point, can be formed. The thin portion 50b is thinner than a portion of the groove bottom 44 from the position where the concave portion 30b is not formed to the outer surface of the circumferential belt 6 in the tire radial direction. The thin portion 50b of the present embodiment constitutes a detection unit that can detect a crack in the circumferential belt 6. The details will be described later (see FIG. 5).

  In FIGS. 3 and 4, the thin portions 50a and 50b are formed by providing the concave portions 30a and 30b as concave portions, but a slit-shaped cut portion is provided instead of the concave portions 30a and 30b. Thus, the thin portions 50a and 50b may be formed. The depressions 30a and 30b mean a configuration in which a state where opposing side walls are separated from each other is maintained during normal traveling. On the other hand, the notch means a configuration in which a state in which opposing side walls are in contact with each other is maintained during normal traveling.

  Next, a detection unit configured by the thin portions 50a and 50b described above will be described.

  By providing the thin portions 50a and 50b as the detection unit, it is possible to detect a crack in the circumferential belt 6 that may cause a failure of the tire 1 before the tire 1 fails. When the circumferential belt 6 cracks in the vicinity thereof, the thin portions 50a and 50b as the detecting portions tear following the crack of the circumferential belt 6. That is, the thin portions 50a and 50b as the detecting portions constitute fragile portions of the tread rubber 7 that are easily torn with the cracks of the circumferential belt 6.

  FIG. 5 is a diagram illustrating a state in which the thin portion 50a serving as the detection unit is torn following the crack in the circumferential belt 6. As shown in FIG. 5, when a crack is formed in a part of the circumferential belt 6, a portion of the tread rubber 7 that straddles the crack in the circumferential belt 6 is subjected to a tearing force due to separation due to the crack in the circumferential belt 6. (See the white arrow in FIG. 5). If the thin portion 50a, which is easily torn as compared with the surroundings, is disposed at the position where the above-described tearing force acts on the tread rubber 7, the position of the thin portion 50a of the tread rubber 7 is caused by the crack of the circumferential belt 6. Cracks can be generated. That is, by visually recognizing the position of the depression 30a on the outer surface of the tread in the tread rubber 7, it is possible to detect whether or not the circumferential belt 6 is cracked. Therefore, it is possible to easily detect a stage where the circumferential belt 6 is cracked before the tire 1 breaks down.

  As described above, by providing the tire 1 with the detection unit capable of detecting the crack in the circumferential belt 6, it is possible to prevent the failure of the tire 1 due to the crack in the circumferential belt 6 beforehand.

  Further, as in the present embodiment, by forming the detecting portion by the thin portion 50a, it is possible to identify a crack in the circumferential belt 6 from the outer surface of the tread of the tire 1. That is, a crack in the circumferential belt 6 that may cause a failure of the tire 1 can be easily notified to the outside of the tire 1. Therefore, the failure of the tire 1 due to the crack of the circumferential belt 6 can be made more difficult to occur.

  Although FIG. 5 illustrates the thin portion 50a as the detection unit, the thin portion 50b operates similarly to the thin portion 50a illustrated in FIG.

  Here, as described above, the circumferential belt 6 is formed of the resin-coated cord 10 wound in a spiral shape. Therefore, in the circumferential belt 6, cracks extending along the tire circumferential direction C are likely to occur at the position of the coating resin 10 a between the cords 10 b in the tire width direction A. For this reason, it is preferable that the thin portions 50a and 50b as the detecting portions shown in FIGS. 3 to 5 have a configuration in which the thin portions 50a and 50b are easily torn against a tearing force (see a white arrow in FIG. Therefore, the depressions 30a and 30b forming the thin portions 50a and 50b as the detection units shown in FIGS. 3 to 5 have a predetermined length (for example, 10 mm or more, more preferably 20 mm or more) in the tire circumferential direction C. It is preferable to have a configuration. Further, even when a cut portion is provided in place of the concave portions 30a and 30b, the cut portion may have a predetermined length (for example, 10 mm or more, more preferably 20 mm or more) in the tire circumferential direction C. preferable. In this manner, the thin portions 50a and 50b that can be easily torn against the tearing force in the tire width direction A can be realized.

  In addition, it is preferable that the thin portions 50a and 50b are arranged in the vicinity of a portion of the circumferential belt 6 where cracks easily occur. For example, a large contact pressure easily acts on both ends of the circumferential belt 6 in the tire width direction A. In order to make it easier to detect a crack in the circumferential belt 6 due to the contact pressure, a recess 30b is provided in the groove bottom 44 of the width direction groove 7b of the end land portion 15c, and the end of the circumferential belt 6 in the tire width direction A is provided. The thin portion 50b may be formed at a position outside the tire radial direction B with respect to the portion. In particular, as described above, the circumferential belt 6 of the present embodiment has reduced-diameter portions 13 and 14 (see FIG. 1) at both ends in the tire width direction A. At the positions of the reduced diameter portions 13 and 14, distortion tends to increase. Therefore, in the circumferential belt 6 having the reduced diameter portions 13 and 14 at both ends in the tire width direction A as in the present embodiment, it is preferable to provide the detection units near the positions of both ends in the tire width direction A. That is, it is preferable to form the thin portion 50b by providing the recess 30b in the width direction groove 7b of the end land portion 15c. Further, even when the concave portion 30a is provided in the circumferential groove 7a to form the thin portion 50a, it is preferable to provide the concave portion 30a in the outer circumferential groove 7a2 located outside the tire width direction A.

  As described above, the tire 1 of the present embodiment includes the resin annular body 5 inside the circumferential direction belt 6 in the tire radial direction B, but does not have the resin annular body 5 and has a crown portion of the carcass 4. A configuration in which the circumferential belt 6 is stacked outside the tire radial direction B may be employed.

  Note that a plurality of the depressions 30a may be formed in the tire circumferential direction C in one circumferential groove 7a as the groove 20. That is, a plurality of thin portions 50a may be formed at the same position in the tire width direction A and at different positions in the tire circumferential direction C. Further, one or more depressions 30a may be formed in each of the plurality of circumferential grooves 7a. That is, a plurality of thin portions 50a may be formed at the same position in the tire circumferential direction C and at different positions in the tire width direction A. In this manner, a plurality of thin portions 50a may be formed at different positions in the tire width direction A and at different positions in the tire circumferential direction C.

  Further, a plurality of the recessed portions 30b may be formed in the tire width direction A in one width direction groove 7b as the groove portion 20. That is, a plurality of thin portions 50b may be formed at the same position in the tire circumferential direction C and at different positions in the tire width direction A. Furthermore, one or more depressions 30b may be formed in each of the plurality of width direction grooves 7b. That is, a plurality of thin portions 50b may be formed at the same position in the tire width direction A and at different positions in the tire circumferential direction C. In this way, a plurality of thin portions 50b may be formed at different positions in the tire width direction A and at different positions in the tire circumferential direction C.

  Hereinafter, further details of the thin portions 50a and 50b as the detection unit of the present embodiment will be described.

  As shown in FIG. 3, the thin portion 50a of the tread rubber 7 of the present embodiment includes a skin portion 61a and an identification portion 62a.

  The skin portion 61a includes a recess 30a in the groove bottom 42 of the circumferential groove 7a as the groove 20.

  The identification portion 62a is located inside the skin portion 61a in the tire radial direction B, and has a configuration that can be visually identified from the skin portion 61a. Specifically, the identification section 62a of the present embodiment is made of rubber of a different color from the skin section 61a. The skin portion 61a is made of, for example, black rubber, and the identification portion 62a is made of, for example, red rubber.

  As shown in FIG. 4, the thin portion 50b of the tread rubber 7 of the present embodiment includes a skin portion 61b and an identification portion 62b.

  The skin portion 61b includes a concave portion 30b of the groove bottom 44 of the width direction groove 7b as the groove portion 20.

  The identification portion 62b is located inside the skin portion 61b in the tire radial direction B, and has a configuration that can be visually identified from the skin portion 61b. Specifically, the identification portion 62b of the present embodiment is made of rubber having a different color from the skin portion 61b, like the thin portion 50a described above. The skin portion 61b is made of, for example, black rubber, and the identification portion 62b is made of, for example, red rubber.

  As described above, since the thin portions 50a and 50b have the identification portions 62a and 62b, when the thin portions 50a and 50b are cracked, the skin portions 61a and 61b are torn, and the identification portions 62a and 62b are connected to the tread of the tire 1. It becomes visible from the outside. Thereby, it is possible to more easily identify a state where the thin portions 50a and 50b are cracked. In other words, a crack in the circumferential belt 6 that may cause a failure of the tire 1 can be more reliably reported outside the tire 1. Therefore, the failure of the tire 1 due to the crack of the circumferential belt 6 can be made more difficult to occur.

  In the thin portion 50a, the skin portion 61a is formed of a rubber material different from that of the identification portion 62a. Specifically, the skin portion 61a of the thin portion 50a is formed of a rubber material that is more easily broken than the identification portion 62a. The skin portion 61b of the thin portion 50b is also formed of a rubber material different from that of the identification portion 62b. Specifically, the skin portion 61b of the thin portion 50b is formed of a rubber material that is more easily broken than the identification portion 62b. The skin portions 61a and 61b are formed of a rubber material forming the outer surface of the tread.

  In the present embodiment, since the skin portions 61a and 61b and the identification portions 62a and 62b are made of different rubber materials, of the tread rubber 7, the identification portions 62a and 62b and the portions other than the identification portions 62a and 62b are different. Although it is formed of a rubber material, the present invention is not limited to this configuration. For example, the tread rubber may be formed of different materials for the skin portions 61a and 61b, the identification portions 62a and 62b, and other portions. .

  FIG. 6 is a view showing a modification of the circumferential groove 7a and the width groove 7b as the groove 20. FIG. 6 is a development view of the outer surface of the tread. Of the groove walls 142 of the circumferential groove 107a as the groove 20 shown in FIG. 6, the specific groove wall 171a of the portion where the recess 30a is formed is around the specific groove wall 171a of the circumferential groove 107a as the groove 20. Has an outer shape that can be identified from the peripheral groove wall 172a located at the center position. Specifically, the specific groove wall 171a of the present embodiment has at least a portion wider than the peripheral groove wall 172a. More specifically, the specific groove wall 171a shown in FIG. 6 has a star shape in a plan view (similar to the developed view shown in FIG. 6) of the tread outer surface when the tread outer surface is viewed from the front, and the peripheral groove wall 172a. It has a shape different from that of FIG. The peripheral groove wall 172a of the circumferential groove 107a is formed by a pair of wall surfaces extending substantially parallel to the tire circumferential direction C in plan view of the outer surface of the tread. Further, the specific groove wall 171a shown in FIG. 6 has a star shape, but may have another shape such as a circular shape or another polygon shape that can be distinguished from the peripheral groove wall 172a.

  Further, in the groove wall 144 of the width direction groove 107b as the groove portion 20 shown in FIG. 6, the specific groove wall 171b of the portion where the recess 30b is formed is the specific groove wall 171b of the width direction groove 107b as the groove portion 20. Has an outer shape that can be distinguished from the peripheral groove wall 172b located around the periphery. Specifically, the specific groove wall 171b of the present embodiment has at least a portion wider than the peripheral groove wall 172b. More specifically, the specific groove wall 171b shown in FIG. 6 has a circular shape in plan view of the outer surface of the tread, and has a shape different from the peripheral groove wall 172b. The peripheral groove wall 172b of the width direction groove 107b is formed by a pair of wall surfaces extending substantially parallel to the tire width direction A in a plan view of the tread outer surface. Further, the specific groove wall 171b shown in FIG. 6 has a circular shape, but may have another shape such as a star shape or another polygon shape that can be distinguished from the peripheral groove wall 172b.

  By providing the specific groove walls 171a and 171b as shown in FIG. 6, the thin portions 50a and 50b as the detecting portions can be more easily specified from the outer surface of the tread of the tire 1, and the outside of the thin portions 50a and 50b can be specified. Can be improved.

  Note that the side rubber 8 (see FIG. 1) provided in the sidewall portion 1b may include a display portion that allows the positions of the above-described recessed portions 30a and 30b in the tire circumferential direction C to be identified from the outside. Examples of the display unit include an identification mark indicating the position of the depressions 30a and 30b in the tire circumferential direction C, or the like. By doing so, the positions of the depressions 30a and 30b in the tire circumferential direction C, and thus the positions of the thin portions 50a and 50b in the tire circumferential direction C, can be more easily grasped from outside the tire 1. .

<Second embodiment>
Next, a pneumatic tire 201 (hereinafter simply referred to as “tire 201”) as another embodiment different from the above-described first embodiment will be described.

  The tire 201 of the present embodiment is different from the above-described tire 1 in the configuration of the detection unit, but has the other configurations in common. Here, differences will be mainly described, and descriptions of common configurations will be omitted.

  FIG. 7 is a diagram illustrating the circumferential belt 6 of the tire 201 and the detection unit. FIG. 7 shows the circumferential belt 6 and the detection unit when the tire 201 is viewed from the tread outer surface side. In addition, the case where the tire 201 is viewed from the outer surface of the tread means the case where the outer surface of the tread of the tire 201 is viewed from the outside in the tire radial direction B toward the inside.

  As illustrated in FIG. 7, the detection unit according to the present embodiment includes an RFID tag 280. Specifically, in the present embodiment, a crack in the circumferential belt 6 can be detected based on the communication state of the RFID tag 280.

  As shown in FIG. 7, the RFID tag 280 as a detection unit includes an antenna 281 and a control circuit 282. The control circuit 282 includes a processor including a CPU or an MPU, and a memory capable of storing various information.

  The antenna 281 of the RFID tag 280 is joined to the circumferential belt 6. Specifically, the antenna 281 is joined to the outer surface of the circumferential belt 6 in the tire radial direction B by welding, bonding, or the like.

  As shown in FIG. 7, the antenna 281 extends in the tire width direction so as to intersect the cord 10b of the circumferential belt 6 in a spiral state at a plurality of positions when viewed from the tread outer surface side. A extends over at least a part of the region of A. That is, in a plan view shown in FIG. 7, the antenna 281 of the RFID tag 280 extends so as to intersect with the cord 10b of the resin-coated cord 10 wound in a spiral shape. FIG. 8 is a diagram illustrating a case where a crack occurs in a portion of the coating resin 10a that is covered by the antenna 281. As shown in FIG. 8, when a portion of the coating resin 10 a between the cords 10 b of the circumferential belt 6 that is covered with the antenna 281 has a crack, the antenna 281 is separated by the crack of the coating resin 10 a. A tensile force also acts on this (see the white arrow in FIG. 8). When the antenna 281 is disconnected due to the tensile force, the RFID tag 280 cannot transmit or receive information. That is, in the present embodiment, the detection unit is configured by the RFID tag 280, and detects a crack in the circumferential belt 6 based on a communication state with the RFID tag 280.

  Specifically, when the RFID tag 280 cannot communicate, it is determined that the antenna 281 is disconnected due to a crack in the circumferential belt 6. Therefore, for example, if a communication device that is installed outside the tire 201 such as a vehicle and can normally communicate with the RFID tag 280 cannot communicate with the RFID tag 280, the communication device may break in the circumferential belt 6 Can be notified to the outside by a message or sound. As described above, by configuring the detection unit with the RFID tag 280, it is possible to easily notify the outside of the tire 201 of a crack in the circumferential belt 6 that may cause a failure of the tire 201.

  As shown in FIG. 7, the antenna 281 of the RFID tag 280 has a linear shape in a direction inclined at an angle of 10 ° or more with respect to the extending direction of the cord 10b of the circumferential belt 6 when viewed from the tread outer surface side. It is preferable to extend. By doing so, the antenna 281 of the RFID tag 280 easily intersects with the cord 10b of the resin-coated cord 10 wound spirally in the plan view shown in FIG. In particular, the antenna 281 preferably extends linearly in a direction orthogonal to the extending direction of the cord 10b when viewed from the outer surface of the tread.

  As described above, the circumferential belt 6 is constituted by the resin-coated cord 10 wound in a spiral shape. Therefore, as shown in FIG. 7, it is preferable to arrange the antenna 281 so as to straddle more welding interfaces IF. In this manner, cracks at the plurality of welding interfaces IF of the circumferential belt 6 can be detected in a wider range. In particular, if the antenna 281 is configured to extend linearly in a direction orthogonal to the extending direction of the cord 10b in a plan view of the outer surface of the tread, the length of the antenna 281 can be further reduced. In addition, the size of the RFID tag 280 can be reduced.

  In the circumferential belt 6 composed of the resin-coated cord 10 wound in a helical manner, the antenna 281 of the RFID tag 280 as a detection unit is moved over the entire area of the circumferential belt 6 in the tire width direction A. It is preferable to arrange them. In this way, the antenna 281 is disconnected before the crack of the circumferential belt 6 progresses spirally along the welding interface IF, that is, at the stage when the crack progresses at most for one round, and the circumferential direction belt 6 is broken. A crack in the belt 6 can be detected more widely and earlier.

  FIG. 7 illustrates an example in which one RFID tag 280 as a detection unit is arranged, but a plurality of RFID tags 280 may be arranged at different positions in the tire width direction A. Further, a plurality of RFID tags 280 may be arranged at different positions in the tire circumferential direction C.

  The pneumatic tire according to the present invention is not limited to the specific configurations shown in the above-described embodiments and modifications, and various modifications and changes can be made without departing from the scope of the claims.

  The present invention relates to a pneumatic tire.

1, 201: pneumatic tire, 1a: tread, 1b: sidewall, 1c: bead, 3: bead member, 3a: bead core, 3b: bead filler, 4: carcass, 4a: carcass ply, 5: resin ring Body, 6: circumferential belt, 7: tread rubber, 7a, 107a: circumferential groove, 7a1: central side circumferential groove, 7a2: outer circumferential groove, 7b, 107b: width direction groove, 8: side rubber, 9: Inner liner, 10: resin-coated cord, 10a: coated resin, 10b: cord, 13, 14: reduced diameter portion, 15: land portion, 15a: central land portion, 15b: middle land portion, 15c: end land portion, 20: groove portion, 30a, 30b: recess portion, 41: groove wall of circumferential groove, 42: groove bottom of circumferential groove, 43: groove wall of width direction groove, 44: groove of width direction groove 50a, 50b: thin portion (detection portion), 61a, 61b: skin portion of the thin portion, 62a, 62b: identification portion of the thin portion, 142: groove wall of circumferential groove, 144: groove wall of width groove, 171a: specific groove wall of the circumferential groove 171b: specific groove wall of the width groove 172a: peripheral groove wall of the circumferential groove 172b: peripheral groove wall of the width groove 280: RFID tag (detection unit), 281 : Antenna, 282: control circuit, A: tire width direction, B: tire radial direction, C: tire circumferential direction, W: tire contact width, CL: tire equatorial plane, IF: welding interface, TE: tread edge

Claims (7)

A cord in a spirally wound state, and a circumferential belt including a coating resin covering the cord, a pneumatic tire including a tread portion,
A pneumatic tire, comprising: a detection unit capable of detecting a crack in the circumferential belt. A tread rubber that is located on the outer side in the tire radial direction of the circumferential belt and has a groove formed on an outer surface of the tread,
In the groove bottom of the groove portion of the tread rubber, a tire radial direction thickness up to the tire radial direction outer surface of the circumferential belt, a recessed portion or a cut portion that is smaller than a position around the groove bottom of the groove portion. Is formed,
The detection unit, of the tread rubber, is configured by a thin portion that is a portion from the recessed portion or the cut portion of the groove bottom of the groove portion to the outer surface in the tire radial direction of the circumferential belt from the groove portion, The pneumatic tire according to claim 1.   The thin portion of the tread rubber is located inside the skin portion including the recessed portion or the cut portion at the groove bottom of the groove portion and the cut portion, and is visually identified from the skin portion in the tire radial direction. A pneumatic tire according to claim 2, comprising a possible identification.   The pneumatic tire according to claim 3, wherein the skin portion is formed of a rubber material different from the identification portion.   Of the groove walls of the groove, the specific groove wall of the portion where the depression or the notch is formed is a peripheral groove wall located around the specific groove wall of the groove in a plan view of the outer surface of the tread. The pneumatic tire according to any one of claims 2 to 4, wherein the pneumatic tire has an outer shape identifiable from: The cord is joined to the circumferential belt and extends at least partially in the tire width direction so as to intersect the cord in a spirally wound state at a plurality of places when viewed from the tread outer surface side. An RFID tag comprising an antenna extending
The pneumatic tire according to claim 1, wherein the detection unit is configured by the RFID tag.   The antenna of the RFID tag extends linearly in a direction inclined at an angle of 10 ° or more with respect to the extending direction of the cord of the circumferential belt when viewed from the outer surface of the tread. The pneumatic tire according to claim 6.

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