pneumatic tires

Abstract

Pneumatic tires (1), comprising: a tread section (2) extending in a circumferential direction of the tire and having a ring-shaped form, wherein the tread section (2) comprises a pair of central main grooves (30C) extending over a tire equator line (CL) in the direction of the tire circumference and a central bridge section (20C) defined by the pair of central main grooves (30C); a pair of sidewall sections (8) arranged on both sides of the running surface section (2); a pair of bead sections (10) each arranged on an inside sidewall section (2) in the tire radial direction; at least one carcass layer (13) extending between the pair of bead sections (10); and a plurality of belt layers (14) arranged on an outer side of the carcass layer (13) in the tire radial direction, wherein the carcass layer (13) comprises carcass cord threads formed from organic fiber cord threads obtained by interlacing a filament bundle of organic fibers, and helix sections (131) each formed by helixing the end sections of the carcass layer (13) at the pair of bead sections (10) towards an outer side in the tire width direction, wherein the carcass cord threads have an elongation at break EB that meets EB ≥ 15%, and wherein an average total thickness GC of the central rib section (20C) located within a range of 10% of the width of a second widest belt in the belt layer (14) on both a right and a left side of the tire equator line (CL) in the tire width direction, an average thickness SG of a sound-absorbing element (100) arranged inside the pneumatic tire (100) and located within an area identical to an area of ​​the central rib section (20C) in the tire width direction, and the elongation at break EB of the carcass cord threads 15 ≤ ( GC / ( GC + ( SG / 10 ) ) ) × EB ( % ) ≤ 25 fulfill.

Description

Technical field

[0001] The present invention relates to an air tire which includes a carcass layer including organic fiber cord threads. State of the art

[0002] Some pneumatic tires include carcass plies that extend between a pair of bead sections (see JP 2015-231772 A and JP 2015-231773 A). One cause of failure of a pneumatic tire that includes carcass plies is damage (impact bursting) inflicted on the tire due to a strong impact while driving, resulting in a rupture of the carcass plies within the tire.

[0003] For example, resistance to such damage (burst resistance) can be determined using a piston test. The piston test measures the rupture energy generated when a tire bursts by pressing a piston of a predetermined size against a central section of the tread on the tire surface. Thus, the piston test can be used as an indicator of the rupture energy (resistance to impact forces on the tread section) when the tire rolls over protrusions on an uneven road surface.

[0004] DE 11 2014 006 241 B4 discloses a pneumatic tire comprising a tread section, two sidewall sections, two bead sections, a sound-dampening element bonded to the inner surface of the tire, a carcass layer extending between the two bead sections, and a belt cover layer with fiber cords arranged on an outer circumference of the belt layer and extending across the entire width of the belt layer (15). Furthermore, the pneumatic tire has a belt edge cover layer consisting of at least one layer of fiber cord, arranged on an outer circumference of the belt cover layer such that it covers two edges of the belt layer. The pneumatic tire also has a tread rubber layer arranged on an outer circumference of the belt cover layer and the belt edge cover layer.The sound-absorbing element is located on the inside of the belt edge cover layer in the tire width direction. The thickness of the tread rubber layer in the area above which the sound-absorbing element is located is constant. The difference between the thickness of the tread rubber layer at a position at the edges of the sound-absorbing element and the thickness of the tread rubber layer at a position at the tire's equator is no more than 0.5 mm. The thickness of the tread rubber layer in an area above which the belt edge cover layer is located is less than the thickness above an area where the sound-absorbing element is located. The difference between (i) the minimum thickness of the tread rubber layer above the area where the belt edge cover layer is located and (ii) the thickness of the tread rubber layer at the tire's equator is between 1.0 and 4.0 mm.

[0005] EP 3 192 669 A1 discloses a pneumatic tire with a resin tire frame element, on the inner surface of which a fastening section is provided, which is designed in such a way that a sound-absorbing material is attached inside the tire frame element.

[0006] JP 2016 210 250 A discloses a tire with a sound-absorbing material arranged on an inner cavity surface of the tire. The sound-absorbing material is coated with a film to form a sound-absorbing element. Brief description of the invention: Technical problem

[0007] Rayon fiber cord threads, formed from high-stiffness rayon materials, have often been used as carcass cord threads, forming carcass plies for high-performance vehicle tires. However, in recent years, due to increased vehicle top speeds, demands for weight reduction, and high grip requirements, the thickness, height, and modulus of the rubber (protective tread rubber) in the tire's contact patch have tended to decrease. This can lead to insufficient elongation at break of the carcass plies and reduced impact burst strength.

[0008] Furthermore, a method is known for such a pneumatic tire in which a sound-absorbing element, such as a sponge, is bonded to the inner surface of the tire to reduce cavity resonance. However, when this method is implemented on a tire for a high-performance vehicle with a high top speed, the sound-absorbing element increases heat buildup in a tread section at high speeds, leading to reduced high-speed durability. As a solution to the problem described above, a method for reducing the thickness of the protective tread rubber in the tread section was investigated. However, this method reduces the impact burst resistance.

[0009] In view of the foregoing, it is an object of the present invention to provide a pneumatic tire which provides both high-speed stability and impact burst resistance in a compatible manner, and furthermore exhibits low noise performance, by making proper use of organic fiber cord threads formed from organic fibers having a stiffness comparable to that of rayon materials and having a high elongation at break. Solution to the problem

[0010] To solve the problems described above and to achieve the object described above, an embodiment of the present invention provides a pneumatic tire comprising a tread section extending in the circumferential direction of the tire and having an annular shape, a pair of sidewall sections arranged on both sides of the tread section, a pair of bead sections arranged on an inner side of the sidewall section in the tire radial direction, at least one carcass layer extending between the pair of bead sections, and a plurality of belt layers arranged on an outer side of the carcass layer in the tire radial direction, wherein the carcass layer includes carcass cord threads formed from organic fiber cord threads obtained by interlacing a filament bundle of organic fibers, and includes hem sections.which are each formed by folding end sections of the carcass layer at the pair of bead sections to an outside in the tire width direction, wherein the carcass cord threads have an elongation at break EB that satisfies EB ≥ 15%, the tread section includes a pair of central main grooves extending over a tire equator line in the tire circumferential direction, and includes a central rib section defined by the pair of central main grooves, and an average total thickness GC of the central rib section located within a region of 10% of the width of a second-widest belt in the belt layer on each right and left side of the tire equator line in the tire width direction, an average thickness SG of a sound-absorbing element arranged inside the pneumatic tire and located within a regionwhich is identical to the area of ​​the central rib section in the tire width direction, and the elongation at break EB of the carcass cord threads 15 ≤ GC / (GC + SG / 10) × EB (%) ≤ 25.

[0011] Furthermore, in the pneumatic tire described above, the average total thickness GC and the average thickness SG of the sound-absorbing element preferably meet 5 ≤ GC + SG / 10 ≤ 11.

[0012] Furthermore, in the pneumatic tire described above, the carcass cord threads preferably exhibit an intermediate elongation EM under a load of 1.0 cN / dtex that meets EM ≤ 5.0 %.

[0013] Furthermore, in the pneumatic tire described above, the carcass cord threads preferably have a standard fineness CF that meets 4000 dtex ≤ CF ≤ 8000 dtex.

[0014] Furthermore, after dip treatment, the carcass cord threads preferably have a twist coefficient CT of CT ≥ 2000 (T / dm) × dtex 0,5fulfilled. Advantageous effects of the invention

[0015] The pneumatic tire according to an embodiment of the present invention achieves the effect of providing both high-speed stability and impact burst resistance in a compatible manner and enabling the attainment of low-noise performance. Brief description of the drawings Fig. Figure 1 is a meridian cross-sectional view illustrating a main section of an air tire according to an embodiment of the present invention. Fig. Figure 2 is a side view illustrating a vehicle on which pneumatic tires are mounted according to an embodiment of the present invention. Fig. Figure 3 is a diagram of a vehicle fitted with pneumatic tires according to an embodiment of the present invention, as seen from behind the vehicle. Fig.Figure 4 is a schematic view illustrating an example in which a sound-absorbing element is arranged inside a pneumatic tire according to an embodiment of the present invention. Description of embodiments

[0016] Pneumatic tires according to embodiments of the present invention are described in detail below with reference to the drawings. However, the present invention is not limited to these embodiments. Components of the following embodiments include elements that are essentially identical or that can be substituted or easily devised by a person skilled in the art. Types of pneumatic tires

[0017] Herein, "tire radial direction" refers to the direction perpendicular to a tire rotation axis RX, which corresponds to the axis of rotation of a pneumatic tire 1. "Inside in tire radial direction" refers to the side in the direction of the tire rotation axis RX in the tire radial direction. "Outside in tire radial direction" refers to the side facing away from the tire rotation axis RX in the tire radial direction. The term "tire circumferential direction" refers to a circumferential direction with the tire rotation axis RX as its central axis. Furthermore, the tire equatorial plane CL is a plane that lies perpendicular to the tire rotation axis RX and passes through the center of the tire width of the pneumatic tire 1. The position of the tire equatorial plane CL in the tire width direction is aligned with the centerline in the tire width direction, which corresponds to the center position of the pneumatic tire 1 in the tire width direction.The "tire equator line" refers to a line in the circumferential direction of the pneumatic tire 1 that lies on the tire equatorial plane CL. "Tire width direction" refers to the direction parallel to the tire's axis of rotation RX. The term "inside in tire width direction" refers to the side facing the tire equatorial plane (tire equator line) CL in the tire width direction. The term "outside in tire width direction" refers to the side facing away from the tire equatorial plane CL in the tire width direction. The tire width is the width in the tire width direction between sections located on the outermost sides in the tire width direction. In other words, the tire width is the distance between sections that are furthest from the tire equatorial plane CL in the tire width direction.

[0018] In the present embodiment, the pneumatic tire 1 is a tire for a passenger car. The term "tire for a passenger car" refers to a pneumatic tire as specified in Chapter A of the JATMA YEAR BOOK (Standards of The Japan Automobile Tyre Manufacturers Association, Inc.). While the present embodiment describes a tire for a passenger car, the pneumatic tire 1 could also be a tire for a light truck as defined in Chapter B, or a tire for a truck and bus as defined in Chapter C. Furthermore, the pneumatic tire 1 could be a standard tire (summer tire) or a studless tire (winter tire).

[0019] Fig. Figure 1 is a meridian cross-sectional view illustrating a main section of the pneumatic tire 1 according to a first embodiment. The term "meridian cross-section" refers to a cross-section perpendicular to the tire's equatorial plane CL. Fig. Figure 2 is a side view illustrating a vehicle 500 on which the pneumatic tires 1 are mounted according to the present embodiment. Fig. Figure 3 is a diagram of the vehicle 500, on which the pneumatic tires 1 according to the present embodiment are mounted, as viewed from behind the vehicle 500. The pneumatic tire 1 according to the present embodiment, which is mounted on a rim of a wheel 504 of the vehicle 500, is shown in the diagram. Fig. 2 and Fig. The vehicle 500 shown in the illustration rotates around the tire rotation axis Rx.

[0020] In the pneumatic tire 1 according to the present embodiment, when viewed in a tire meridional cross-section, a tread section 2, extending in the circumferential direction and having a ring shape, is arranged at the outermost section in the tire radial direction. The tread section 2 includes a tread rubber layer 4, which is formed from a rubber compound. Furthermore, a surface of the tread section 2, that is, a section that comes into contact with road surfaces during the operation of the vehicle 500 on which the pneumatic tires 1 are mounted, is designed as a tread contact surface 3, and the tread contact surface 3 forms a section of a contour of the pneumatic tire 1. In particular, the protective tread rubber corresponds to the tread rubber layer 4 on the inner side of the tread contact surface 3 in the tire radial direction.

[0021] The tread contact surface 3 of the tread section 2 is provided with a plurality of main circumferential grooves 30 extending in the tire's circumferential direction, as well as with a plurality of lug grooves (not illustrated) extending in the tire's width direction. The term "main circumferential groove 30" refers to a groove extending in the tire's circumferential direction that includes a tread wear indicator (slip mark) within it. The tread wear indicator shows the final stage of wear of the tread section 2. The main circumferential groove 30 has a width of 4.0 mm or more and a depth of 5.0 mm or more. Note that "lug groove" refers to a groove that extends at least partially in the tire's width direction. The lug groove has a width of 1.5 mm or more and a depth of 4.0 mm or more. It should be noted that the grooves in the cleats may sometimes have a depth of less than 4.0 mm.

[0022] The main circumferential groove 30 can extend linearly in the tire's circumferential direction or can form a wave or zigzag shape in the tire's width direction as it extends in the tire's circumferential direction. Furthermore, the lug grooves can also extend linearly in the tire's width direction, be inclined in the tire's circumferential direction as they extend in the tire's width direction, or be bent or curved in the tire's circumferential direction as they extend in the tire's width direction.

[0023] Furthermore, the tread contact surface 3 of the tread section 2 encloses a plurality of rib sections 20 by means of the main circumferential grooves 30 and lug grooves. In the present embodiment, four of the main circumferential grooves 30 are arranged parallel in the tire width direction. Additionally, of the two main circumferential grooves 30, which are arranged in a left and a right region delimited by the tire equatorial plane CL, the main circumferential groove 30 located on the outermost side in the tire width direction (the outermost main circumferential groove) is defined as a shoulder main groove 30S, and the main circumferential groove 30 located on the innermost side in the tire width direction (the innermost main circumferential groove) is defined as a central main groove 30C. The shoulder main groove 30S and the central main groove 30C are each defined in the left and right regions delimited by the tire equatorial plane CL.

[0024] It should be noted that, although not illustrated, one of the two shoulder main grooves 30S may be a narrow circumferential groove. The narrow circumferential groove is a narrow groove that extends continuously in the tire's circumferential direction and runs parallel to the tire's circumference. The narrow circumferential groove, as described above, has a groove width of 3.0 mm or more and 7.0 mm or less. Furthermore, the narrow circumferential groove has a groove depth of 3.0 mm or more and 7.0 mm or less. However, the narrow circumferential groove has a sufficiently small groove width and depth relative to the main circumferential groove 30. In other words, the groove width and depth of the narrow circumferential groove are smaller than the groove width and depth of the main circumferential groove 30.

[0025] Of the majority of rib sections 20 defined by the main circumferential grooves 30, the rib section 20 located further outward in the tire width direction than the main shoulder groove 30S is defined as a shoulder rib section 20S, the rib section 20 between the main shoulder groove 30S and the central main groove 30C is defined as a middle rib section 20M, and the rib section 20 located further inward in the tire width direction than the central main groove 30C is defined as a central rib section 20C. Specifically, of the majority of rib sections 20 on the surface of the tread section 2, the rib section 20 on the outermost side in the tire width direction is defined as the shoulder rib section 20S, and the rib section 20 on the innermost side in the tire width direction is defined as the central rib section 20C.The central rib section 20C encloses a tire equatorial plane (tire equator line) CL in the tire width direction.

[0026] Shoulder sections 5 are positioned at both ends of the tread section 2 in the tire width direction (positioned further outwards than the shoulder rib section 20S), and a pair of sidewall sections 8 are arranged on the inner side of each shoulder section 5 in the tire radial direction. In other words, the pair of sidewall sections 8 are arranged on both sides of the tread section 2 in the tire width direction. The sidewall sections 8 thus formed constitute the outermost exposed sections of the pneumatic tire 1 in the tire width direction.

[0027] The bead sections 10 are each arranged on the inner side, in the tire radial direction, of the pair of sidewall sections 8. The bead sections 10 are each arranged at two locations on both sides of the tire equatorial plane CL. In other words, the pair of bead sections 10 are arranged in the tire width direction on both sides of the tire equatorial plane CL. Each pair of bead sections 10 is provided with a bead core 11, and a bead filler 12 is provided on the outer side, in the tire radial direction, of the bead core 11. The bead core 11 is an annular element formed by bundling tire bead wires, which are steel wires. The bead filler 12 is a rubber element arranged on the outer side, in the tire radial direction, of the bead core 11.

[0028] Furthermore, a belt layer 14 is arranged in the tread section 2. The belt layer 14 has a multi-layered structure in which a plurality of belts 141 and 142 are stacked. The belts 141, 142, which form the belt layer 14, are formed by covering a plurality of belt cord threads made of steel or an organic fiber material, such as polyester, rayon, or nylon, with coating rubber and by carrying out a rolling process on them. A belt angle, which is defined as the inclination angle of the belt cord threads with respect to the tire's circumferential direction, lies within a predetermined range (for example, 20° or more and 55° or less).

[0029] Furthermore, the belt angles of the two layers of belts 141 and 142 differ from each other. Accordingly, belt layer 14 is configured as a so-called cross-layer structure, in which the two layers of belts 141 and 142 are stacked, with the inclination directions of the belt cord threads intersecting each other. In other words, the two belts 141 and 142 are provided as a so-called pair of cross-belts, in which the belt cord threads of the respective belts 141 and 142 are arranged in mutually intersecting orientations.

[0030] A belt cover 40 is located on the outer surface of the belt layer 14 in the radial direction of the tire. The belt cover 40 is positioned on the outer surface of the belt layer 14 in the radial direction of the tire, covers the belt layer 14 in the circumferential direction of the tire, and serves as a reinforcing layer that strengthens the belt layer 14. The belt cover 40 has a width in the tire width direction that is greater than the width of the belt layer 14 in the tire width direction and covers the belt layer 14 from the outside in the radial direction of the tire. The belt cover 40 extends in the tire width direction over the entire area in which the belt layer 14 is located and covers end sections of the belt layer 14 in the tire width direction. The tread rubber layer 4 of the tread section 2 is positioned on the outer surface of the belt cover 40 in the tread section 2 in the radial direction of the tire.

[0031] Furthermore, the belt cover 40 includes: a complete cover section 41, which is identical in width to the belt cover 40 in the tire width direction, and edge cover sections 45, which are stacked on the complete cover section 41 at two respective locations on both sides of the complete cover section 41 in the tire width direction. Of the two edge cover sections 45, one edge cover section 45 is located on the inside of the complete cover section 41 in the tire radial direction, and the other edge cover section 45 is located on the outside of the complete cover section 41 in the tire radial direction.

[0032] A carcass layer 13 is provided continuously on the inner side of the belt layer 14 in the radial direction of the tire and on the side of the tire equatorial plane CL of the sidewall section 8. In the present embodiment, the carcass layer 13 has a single-layer structure consisting of one carcass ply or a multi-layer structure consisting of a plurality of layered carcass plies and extends in a ring shape between the pair of bead sections 10, which are arranged on both sides in the tire width direction and form the tire's skeleton.

[0033] In particular, the carcass layer 13 is arranged such that it extends from one bead section 10 to the other bead section 10 of the bead sections 10 located on both sides in the tire width direction, and is folded upwards towards the outside in the tire width direction along the bead cores 11 on the bead sections 10 such that it wraps around the bead cores 11 and the bead filler 12. The bead filler 12 is a rubber element arranged in a space formed on the outside of the bead core 11 in the tire radial direction when the carcass layer 13 is folded upwards at the bead core 11 of the bead section 10.

[0034] Furthermore, a rim pad 17, which forms a contact surface of the rim section 10 for a rim flange (not illustrated), is arranged on the inside in the tire radial direction and on the outside in the tire width direction of the rim core 11 and a folded-back section 131 of the carcass layer 13 in the bead section 10. The pair of rim pad 17s extends from the inside in the tire radial direction to the outside in the tire width direction of the left and right rim cores 11 and the folded-back sections 131 of the carcass layer 13 and form rim mating surfaces of the rim sections 10. In addition, the belt layer 14 is arranged on the outside in the tire radial direction of a section of the carcass layer 13 located in the tread section 2, which extends between the pair of rim sections 10.

[0035] Furthermore, the carcass layer 13 is formed by covering a plurality of carcass cord threads made of organic fibers with coating rubber or rubber and performing a rolling process on it. A plurality of carcass cord threads forming the carcass layers are arranged next to each other at an angle in the tire's circumferential direction, the angle following a tire meridian direction with respect to the tire's circumferential direction.

[0036] In the present embodiment, the carcass layer 13 includes at least one carcass layer (textile carcass) including organic fiber cord threads (textile cord threads). The carcass layer 13 of the present embodiment includes the hem section 131 at both end sections. The carcass layer 13 includes at least one textile carcass that is wrapped around the bead cores 11, each of which is provided in the pair of bead sections 10.

[0037] The carcass cord threads that form the carcass layer of carcass layer 13 are organic fiber cord threads enclosing filament bundles of interwoven organic fibers. The type of organic fibers forming the carcass cord threads is not subject to any specific restrictions, and, for example, polyester fibers, nylon fibers, aramid fibers, or the like may be used. Polyester fibers are a suitable organic fiber. Examples of suitable polyester fibers include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polybutylene naphthalate (PBN). Polyethylene terephthalate (PET) is a suitable polyester fiber.

[0038] Additionally, an inner liner 16 is formed along the carcass layer 13 on the inner surface of the carcass layer 13 or on the inner section side of the carcass layer 13 in the pneumatic tire 1. The inner liner 16 is an air-inhibiting layer located on an inner circumferential surface of the tire and covering the carcass layer 13. The inner liner 16 suppresses oxidation due to the exposure of the carcass layer 13 and also prevents air from escaping within the tire. Furthermore, the inner liner 16 includes, for example, a rubber compound containing butyl rubber as a main component, a thermoplastic resin, a thermoplastic elastomer compound containing an elastomer component mixed with the thermoplastic resin, and the like. The inner liner 16 forms an inner tire surface 18, which is a surface on the inside of the pneumatic tire 1. Vehicle mounting position

[0039] As in the Fig. 2 and Fig. As illustrated in Figure 3, the vehicle 500 includes a drive mechanism 501 including the pneumatic tire 1, a vehicle body 502 supported by the drive mechanism 501, and an engine 503 for driving the drive mechanism 501. The drive mechanism 501 includes the wheel 504 supporting the pneumatic tire 1, an axle 505 supporting the wheel 504, a steering mechanism 506 for changing the direction of movement of the drive mechanism 501, and a braking mechanism 507 for slowing down or stopping the drive mechanism 501.

[0040] The vehicle body 502 includes a driver's cab occupied by a driver. The following are arranged in the driver's cab: the accelerator pedal, used to adjust the power of the engine 503; the brake pedal, used to operate the brake apparatus 507; and the steering wheel, used to operate the steering apparatus 506. The driver operates the accelerator pedal, the brake pedal, and the steering wheel. The driver performs these operations to cause the vehicle 500 to move.

[0041] The pneumatic tire 1 is mounted on a rim of the wheel 504 of the vehicle 500. The inside of the pneumatic tire 1, mounted on the rim, is then filled with air. By filling the inside of the pneumatic tire 1 with air, the pneumatic tire 1 is inflated. The term "inflated state of the pneumatic tire 1" refers to the state in which the pneumatic tire 1, mounted on a specified rim, is filled with air up to a certain internal pressure.

[0042] “Specified rim” refers to a rim defined for each pneumatic tire 1 by standards for pneumatic tire 1 and includes a “standard rim” defined by JATMA, a “design rim” defined by TRA, and a “measurement rim” defined by ETRTO.

[0043] "Statuted inflation pressure" refers to an air pressure defined for each pneumatic tire by the standards for pneumatic tire 1 and includes the "maximum inflation pressure" defined by JATMA, the maximum value in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" table defined by TRA, and the "INFLATION PRESSURE" defined by ETRTO. In JATMA, for tires for a passenger car, an air pressure of 180 kPa is the stated inflation pressure.

[0044] Furthermore, "uninflated state of pneumatic tire 1" refers to a state in which the pneumatic tire 1 mounted on the specified rim is not filled with air. In the uninflated state, the internal pressure of the pneumatic tire 1 is atmospheric pressure. In other words, in the uninflated state, the internal and external pressures of the pneumatic tire 1 are essentially the same.

[0045] The pneumatic tire 1, mounted on the rim of vehicle 500, rotates around the tire rotation axis RX and travels on a road surface RS. During the travel of the pneumatic tire 1, the tread contact surface 3 of the tread section 2 touches the road surface RS.

[0046] In a loaded condition of the pneumatic tire 1, mounted on a specified rim, inflated to the specified internal pressure, and placed vertically on a flat surface, and when a specified load is applied to the pneumatic tire 1, "tire ground contact edges" refer to end sections in the tire width direction of a section (tread contact surface 3) of the tread section 2 that comes into contact with the ground. The shoulder rib sections 20S of the tread section 2 are rib sections 20 located on the outermost side in the tire width direction and on the tire's ground contact edge.

[0047] “Statuted Load” refers to a load defined for each tire by the standards for pneumatic tire 1 and includes the “Maximum Load Capacity” defined by JATMA, the maximum value in the “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” table defined by TRA, and “LOAD CAPACITY” defined by ETRTO. However, if pneumatic tire 1 is for a passenger car, the load is assumed to be 88% of the stated load.

[0048] Vehicle 500 is a four-wheeled vehicle. The driving apparatus 501 includes a left front wheel and a left rear wheel, provided on the left side of the vehicle body 502, as well as a right front wheel and a right rear wheel, provided on the right side of the vehicle body 502. The pneumatic tire 1 includes left pneumatic tires 1L, mounted on the left side of the vehicle body 502, and right pneumatic tires 1R, mounted on the right side of the vehicle body 502.

[0049] In the following description, "inside in vehicle width direction" refers, as appropriate, to a section near the center of the vehicle 500 or a direction approaching the center of the vehicle 500 in the vehicle width direction. "Outside in vehicle width direction" refers, as appropriate, to a section far from the center of the vehicle 500 or a direction departing from the center of the vehicle 500 in the vehicle width direction.

[0050] The present embodiment provides for the mounting direction of the pneumatic tire 1 with respect to the vehicle 500. For example, in a case where the tread pattern of the tread section 2 is an asymmetrical pattern, the mounting direction of the pneumatic tire 1 is provided with respect to the vehicle 500. The left pneumatic tire 1L is mounted on the left side of the vehicle 500 such that one sidewall section 8 of the pair of sidewall sections 8 faces the inside in the direction of the vehicle width, and the other sidewall section 8 faces the outside in the direction of the vehicle width. The right pneumatic tire 1R is mounted on the right side of the vehicle 500 such that one sidewall section 8 of the pair of sidewall sections 8 faces the inside in the direction of the vehicle width, and the other sidewall section 8 faces the outside in the direction of the vehicle width.

[0051] In a case where the mounting direction of the tire is intended with respect to the vehicle 500, the pneumatic tire 1 is provided with an indicator section 600 that indicates the intended mounting direction with respect to the vehicle 500. The indicator section 600 is provided on at least one sidewall section 8 of the pair of sidewall sections 8. The indicator section 600 includes a serial symbol that indicates the mounting direction with respect to the vehicle 500. The indicator section 600 includes at least one marking, character, symbol, and pattern. An example of the indicator section 600 that indicates the mounting direction of the pneumatic tire 1 with respect to the vehicle 500 includes characters such as "OUTSIDE" or "INSIDE". The user can determine the mounting direction of the pneumatic tire 1 with respect to the vehicle 500 based on the indicator section 600 provided on the sidewall section 8.Based on the indicator section 600, the left pneumatic tires 1L are mounted on the left side of the vehicle 500, and the right pneumatic tires 1R are mounted on the right side of the vehicle 500. Sound-absorbing element

[0052] A sound-absorbing element 100 is arranged in a space surrounded by the inner surface 18 of the pneumatic tire 1 and a rim mounted on the pneumatic tire 1. The sound-absorbing element 100 is, for example, glued to the inner surface 18 of the tire. The sound-absorbing element 100 is made of a material with sound-dampening properties. The sound-absorbing element 100 reduces the resonance of the air present in the pneumatic tire 1. As in Fig.As illustrated in Figure 4, the sound-absorbing element 100 of the present embodiment is arranged continuously in the circumferential direction of the pneumatic tire 1. The sound-absorbing element 100 cannot be arranged continuously in the circumferential direction of the tire.

[0053] The sound-absorbing element 100 is made of a porous material with a bubble structure, such as a sponge, glass wool, or an elastomer. The sound-absorbing element 100 particularly preferably uses a sponge. The sponge encloses a urethane sponge. Additionally, the elastomer exhibits flexibility and forms a sound-dampening mechanism due to the membrane vibration of cells (bubbles), thereby providing a sound-absorbing structure with good sound-dampening properties. Examples of the elastomer include natural rubber, CR (chloroprene rubber), SBR (styrene-butadiene rubber), NBR (nitrile-butadiene rubber), EPDM (ethylene propylene diene monomer) rubber, silicone rubber, fluororubber, acrylic rubber, thermoplastic elastomer, and soft urethane.

[0054] The pneumatic tire 1 of the present embodiment meets the following conditions. In particular, the elongation at break EB (%) of the carcass cord threads of the carcass layer 13 EB ≥ 15%. The elongation at break EB of the carcass cord threads represents a physical property that is measured on the sidewalls of the pneumatic tire 1.

[0055] Furthermore, the following condition is fulfilled in the pneumatic tire 1 by: the average total thickness GC of the tread rubber layer 4 of the central rib section 20C, which is located within a region of 10% width (10% each on the left and right sides, i.e., a total of 20%) of a width Wb2 of the second widest belt (hereinafter referred to as the second belt) in the belt layer 14 on the left and right sides of the tire equatorial plane CL in the tire width direction; the average thickness SG of the sound-absorbing element 100, which is arranged inside the tire and is located within a region identical to the region of the central rib section 20C in the tire width direction (region of ±10% of the width Wb2 of the second belt); and the elongation at break EB of the carcass cord threads. 15≤(GC / (GC+(SG / 10)))×EB(%)≤25

[0056] With the elongation at break EB (%) of the carcass cord threads of the carcass layer 13 within the range described above, and with the relationship between the average total thickness GC, the average thickness SG, and the elongation at break EB of the carcass cord threads satisfying the formula (1) described above, both the high-speed durability and the impact burst strength of the pneumatic tire 1 can be provided in a compatible manner, while improving the noise performance of the pneumatic tire 1. In particular, bonding the sound-absorbing element 100 allows for the improvement of the noise performance of the pneumatic tire 1; however, heat is likely to build up at high speeds due to the sound-absorbing element 100, resulting in a high-speed durability that is lower than that of a tire with the sound-absorbing element 100 not bonded to the tire.Furthermore, increasing the elongation at break EB of the carcass cord threads improves the impact burst strength of the pneumatic tire 1, although increasing the elongation at break EB of the carcass cord threads tends to reduce the strength (stiffness) of the cord threads. This hinders the suppression of crimping and deformation at high speeds, which worsens high-speed durability.In contrast, for the pneumatic tire 1, with the elongation at break EB (%) of the carcass cord threads of the carcass layer 13 within the range described above and with the relationship between the average total thickness GC, the average thickness SG and the elongation at break EB of the carcass cord threads satisfying the formula (1) described above, both the high-speed resistance and the impact burst resistance of the pneumatic tire 1 can be provided in a compatible manner, improving the noise performance of the pneumatic tire 1.

[0057] Here, in the present embodiment, the widest belt in the belt layer 14 is belt 141, and the second belt is belt 142. In this embodiment, the second belt is the narrowest belt in the belt layer 14. Under the conditions described above, the width Wc of the central rib section 20C in the tire width direction is 20% of the width Wb2 of belt 142, which corresponds to the second belt. In other words, Wc = 0.2 × Wb2 is satisfied.

[0058] Furthermore, the elongation at break EB (%) of the carcass cord threads of the carcass layer 13 preferably meets EB ≥ 20%. Additionally, in the pneumatic tire 1, the average total thickness GC of the central rib section 20C, the average thickness SG of the sound-absorbing element 100, and the elongation at break EB of the carcass cord threads 18 ≤ (GC / (GC + (SG / 10))) × EB (%) ≤ 22.

[0059] Furthermore, the average overall thickness GC preferably meets the requirements of 7 mm ≤ GC ≤ 10 mm. Additionally, the average thickness SG of the sound-absorbing element 100 arranged inside the tire, which is located in the area identical to that of the central rib section 20C in the tire width direction (within the range of ±10% of the width Wb2 of the second belt), preferably meets the requirements of 10 mm ≤ SG ≤ 40 mm and more preferably 20 mm ≤ SG ≤ 30 mm.

[0060] Furthermore, in the pneumatic tire 1 with the conditions described above, the average total thickness GC of the central rib section 20C and the average thickness SG of the sound-absorbing element 100 more preferably meet the following conditions. Fulfilling the range of formula (2) below allows for a further improvement in noise reduction performance and high-speed stability. 5≤GC+SG / 10≤11

[0061] Furthermore, the carcass cord threads of the pneumatic tire 1 preferably have an intermediate elongation EM under a load of 1.0 cN / dtex (nominal fineness) that satisfies EM ≤ 5.0%. Additionally, the nominal fineness NF of the carcass cord threads preferably satisfies 3500 dtex ≤ NF ≤ 7000 dtex.

[0062] “Intermediate elongation under a load of 1.0 cN / dtex” refers to the elongation ratio (%) of sample cord threads measured under a load of 1.0 cN / dtex, wherein the sample cord threads correspond to the carcass cord threads removed from the sidewall sections 8 of the pneumatic tire 1, wherein the sample cord threads are subjected to a tensile test with a length between handles of 250 mm and a tensile speed of 300 ±20 mm / minute in accordance with JIS L1017 “Test procedure for man-made fiber tire cord threads”.

[0063] By reducing the intermediate elongation EM of the carcass cord threads while maintaining the tensile elongation EB of the carcass cord threads, steering stability on dry road surfaces can be improved without deteriorating the impact burst strength of the pneumatic tire 1.

[0064] Furthermore, after dip treatment, the carcass cord threads preferably have the standard fineness CF, which meets 4000 dtex ≤ CF ≤ 8000 dtex. More preferably, the standard fineness CF meets 5000 dtex ≤ CF ≤ 7000 dtex.

[0065] “Standard quantity fineness of carcass cord threads after dip treatment” refers to the fineness measured on the carcass cord threads after the dip treatment has been carried out, and is not a value for the carcass cord threads themselves, but rather a value that includes a dip fluid which adheres to the carcass cord threads after the dip treatment.

[0066] By adjusting the standard quantity fineness CF of the carcass cord threads after dip treatment so that it lies within the range described above, the intermediate elongation EM of the carcass cord threads can be reduced while maintaining the elongation at break EB of the carcass cord threads, thereby providing both steering stability on dry road surfaces and impact burst resistance of the pneumatic tire 1 in a compatible manner.

[0067] Furthermore, in the case of the pneumatic tire 1, the carcass cord threads preferably exhibit a twist coefficient CT after dip treatment that is CT ≥ 2000 (T / dm) × dtex 0,5 fulfilled.

[0068] By adjusting the twist coefficient CT of the carcass cord threads after dip treatment so that it lies within the range described above, the intermediate elongation EM of the carcass cord threads can be reduced while maintaining the elongation at break EB of the carcass cord threads. This ensures both steering stability on dry road surfaces and the impact burst resistance of the pneumatic tire 1 in a compatible manner. Additionally, reducing the intermediate elongation EM of the carcass cord threads while maintaining the elongation at break EB of the carcass cord threads makes the carcass cord threads easily stretchable and difficult to cut. Example

[0069] Tables 1 and 2 show results of performance tests of pneumatic tires according to the present embodiment. In the performance tests, a number of test tire types were evaluated under varying conditions for impact burst resistance, high-speed stability, and noise reduction. For the performance tests, pneumatic tires (test tires) of size 265 / 35ZR20 were mounted on 20 × 9.5J rims, inflated to a pressure of 250 kPa, and fitted to a test passenger car, an FR sedan (total engine displacement of 3000 cm³). 3 ) mounted.

[0070] To assess the impact burst strength, a piston test was performed according to the FMVS139 standard. Impact burst strength was evaluated using index values ​​(sensory assessment), with comparison example 1 serving as the reference (100). Higher values ​​indicate superior impact burst strength.

[0071] To assess high-speed durability, tests were conducted according to the ECE30 standard using a European Class 3L (saloon) vehicle. High-speed durability was evaluated using index values, with comparison example 2 assigned as the reference (100). Higher values ​​indicate a lower probability of failure and superior high-speed durability.

[0072] To assess noise performance, tests were conducted in which the vehicle was driven on roads with road noise (R / N) (unpaved, rough roads, or roads with poor surface conditions). Noise performance was evaluated using index values, with comparison example 1 assigned as the reference (100). Higher values ​​indicate superior noise performance.

[0073] Furthermore, rayon fiber cord threads, formed from high-stiffness rayon materials, have often been used as carcass cord threads, forming carcass plies for high-performance vehicle tires. However, in recent years, due to increased vehicle top speeds, demands for weight reduction, and high grip requirements, the thickness, height, and modulus of the rubber (protective tread rubber) in the tire's road contact patch have tended to decrease. This leads to a tendency for the carcass plies to have insufficient elongation at break, which impairs impact burst resistance. Therefore, as a method to achieve good results in piston testing, a procedure is being investigated that uses organic fiber cord threads with high elongation at break as carcass cord threads, forming a carcass ply to accommodate deformation during testing (when the tire is compressed by the piston).

[0074] On the other hand, the pneumatic tires in comparison examples 1 and 2 and examples 1 to 9 incorporated PET fiber cord threads, made of polyethylene terephthalate material, as the carcass cord threads forming the carcass ply. These threads had a stiffness comparable to that of rayon material and a high elongation at break. Additionally, a sound-absorbing element was bonded to the inner surface of the pneumatic tires. The pneumatic tires were evaluated for impact burst strength, high-speed durability, and noise performance according to the evaluation procedure described below, and the results are also shown in Tables 1 and 2. [Table 1] Comparative example 1 Comparative example 2 Example 1 Example 2 Type of organic fiber material PET PET PET PET Elongation at break EB (%) of the carcass cord threads 10 10 25 30 Average total thickness GC 11 9 9,5 8,5 Average thickness SG of the sound-absorbing element 25 5 25 30 (GC / (GC + (SG / 10))) × EB(%) 8,1 9,5 19,8 22,2 Impact burst resistance 100 70 100 120 High temperature resistance 70 100 100 105 Low noise performance 100 70 100 110 [Table 2-I] Example 1 Example 2 Example 3 Example 4 Example 5 Type of organic fiber material PET PET PET PET PET Elongation at break EB (%) of the carcass cord threads 25 30 30 30 30 Average total thickness GC 9,5 8,5 8,5 7 7 Average thickness SG of the sound-absorbing element 25 30 30 30 30 CG / (CG + SG / 10) × EB 19,8 22,2 22,2 21 21 CG + SG / 10 12 11,5 11,5 4 5 Intermediate elongation EM (%) of the carcass cord threads 6 5 4 6 6 Standard quantity fineness CFder carcass cord threads 3500 5500 5500 3500 3500 Twist coefficient CT of the carcass cord threads 1500 1500 2200 1500 1500 Impact burst resistance 100 120 120 105 105 High temperature resistance 100 105 105 115 115 Low noise performance 100 110 110 105 105 [Table 2-II] Example 6 Example 7 Example 8 Example 9 Type of organic fiber material PET PET PET PET Elongation at break EB (%) of the carcass cord threads 30 30 30 30 Average total thickness GC 7 7 8,5 7 Average thickness SG of the sound-absorbing element 30 30 30 30 CG / (CG + SG / 10) × EB 21 21 22,2 21 CG + SG / 10 10 10 11,5 10 Intermediate elongation EM (%) of the carcass cord threads 4 4 4 4 Standard quantity fineness CFder carcass cord threads 3500 4500 4500 9000 Twist coefficient CT of the carcass cord threads 1500 1500 2200 2200 Impact burst resistance 110 110 120 110 High temperature resistance 110 110 105 110 Low noise performance 110 110 110 110

[0075] As shown in Tables 1 and 2, the pneumatic tires of Examples 1 to 9 achieved better rating results than the pneumatic tires of Comparison Examples 1 and 2. In other words, at least setting the conditions identical to those for the pneumatic tires of Examples 1 to 9, even when using PET fiber cord threads, leads to rating results equivalent to or higher than those obtained by using rayon fiber cord threads, and low noise performance can be achieved with both high-speed durability and impact burst resistance provided in a compatible manner. List of reference symbols 1 pneumatic tire 2. Tread section 3 Running surface contact surface 4 tread rubber layers 5 Shoulder section 8 Side wall section 10 bead section 11 bead core 12 bead fillers 13 Carcass layer 14 Belt layer 141, 142 Belts 16 Inner Soul 17 Wheel rim pad rubber 18 Tire inner surface 20 Bridge section 20S shoulder strap section 20M Middle Bridge Section 20C Central Bridge Section 30 Main circumferential groove 30S Shoulder Groove 30C Central Main Groove 40 belt cover 41 Full coverage section 45 Edge cover section 100 sound-absorbing element 500 vehicles 501 Driving apparatus 502 Vehicle body 503 Engine 504 wheel 505 axle 506 Steering apparatus 507 Brake apparatus 600 indicator section

Claims

[1] Pneumatic tires (1), comprising: a tread section (2) extending in a circumferential direction of the tire and having a ring-shaped form, wherein the tread section (2) comprises a pair of central main grooves (30C) extending over a tire equator line (CL) in the direction of the tire circumference and a central bridge section (20C) defined by the pair of central main grooves (30C); a pair of sidewall sections (8) arranged on both sides of the running surface section (2); a pair of bead sections (10) each arranged on an inside sidewall section (2) in the tire radial direction; at least one carcass layer (13) extending between the pair of bead sections (10); and a plurality of belt layers (14) arranged on an outer side of the carcass layer (13) in the tire radial direction, wherein the carcass layer (13) comprises carcass cord threads formed from organic fiber cord threads obtained by interlacing a filament bundle of organic fibers, and helix sections (131) each formed by helixing the end sections of the carcass layer (13) at the pair of bead sections (10) towards an outer side in the tire width direction, wherein the carcass cord threads have an elongation at break EB that meets EB ≥ 15%, and wherein an average total thickness GC of the central rib section (20C) located within a range of 10% of the width of a second widest belt in the belt layer (14) on both a right and a left side of the tire equator line (CL) in the tire width direction, an average thickness SG of a sound-absorbing element (100) arranged inside the pneumatic tire (100) and located within an area identical to an area of ​​the central rib section (20C) in the tire width direction, and the elongation at break EB of the carcass cord threads 15≤(GC / (GC+(SG / 10)))×EB(%)≤25 fulfill. [2] Pneumatic tires(1) according to claim 1, wherein the average total thickness GC and the average thickness SG of the sound-absorbing element (100) 5≤GC+SG / 10≤11 fulfill. [3] Pneumatic tire (1) according to claim 1 or 2, wherein the carcass cord threads have an intermediate elongation EM under a load of 1.0 cN / dtex which EM≤5.0% fulfilled. [4] Pneumatic tire (1) according to any one of claims 1 to 3, wherein the carcass cord threads have a standard fineness CF, which 4000 dtex ≤ CF ≤ 8000 dtex fulfilled. [5] Pneumatic tire (1) according to any one of claims 1 to 4, wherein the carcass cord threads have a twist coefficient CT after dipping treatment which CT≥2000(T / dm)×dtex0.5 fulfilled.

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