pneumatic tires

Abstract

Pneumatic tire (1) comprising: a tread section (2) extending in a circumferential direction and having a ring shape; a pair of sidewall sections (8) arranged on both sides of the tread section (2); a pair of bead sections (10) arranged on an inner side of the sidewall sections (8) in the radial direction of the tire; at least one carcass layer (13) arranged 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 radial direction of the tire, wherein the carcass layer (13) comprises carcass cord threads formed from organic fiber cord threads obtained by interlacing a bundle of filaments of organic fibers, and wrap sections (131) formed by folding end sections of the pair of bead sections (10) to an outer side in the width direction of the tire.the carcass cord threads have an elongation at break EB that satisfies EB ≥ 15%, a section of the belt layer (14) located in a width range of 10% of the width of a second-widest belt in the belt layer (14) on the left and right sides of a tire equator line (CL) in the direction of tire width has a belt angle θc that satisfies 0.3 rad ≤ θc ≤ 0.6 rad, and the elongations at break EB of the carcass cord threads and the belt angle θc satisfy 800 < 1140 × θc + 20 × EB < 1400.

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 incorporate carcass plies arranged between a pair of bead sections (see patent documents 1 and 2). One cause of failure in a pneumatic tire incorporating 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. List of oppositions patent literature Patent Document 1: JP 2015-231772 A Patent Document 2: JP 2015-231773 A Brief description of the invention: Technical problem

[0004] Rayon fiber cord threads, formed from high-stiffness rayon materials, are frequently used as carcass cord threads, forming the 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 results in insufficient elongation at break of the carcass plies and reduced impact burst strength.

[0005] In light of the foregoing, an object of the present invention is to provide a pneumatic tire which provides both low rolling resistance and impact burst strength in a compatible manner by using organic fiber cord threads formed from organic fibers which have a stiffness comparable to that of rayon materials and exhibit high elongation at break in the correct manner. Solution to the problem

[0006] To solve the problems described above and to achieve the objective 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 each arranged on an inner side of the sidewall section in the tire radial direction, at least one carcass layer arranged 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 comprises carcass cord threads formed from organic fiber cord threads obtained by interlacing a bundle of filaments of organic fibers, and includes wrap sections.which are formed by folding end sections of the pair of bead sections to an outer side in the tire width direction, wherein the carcass cord threads have an elongation at break EB that satisfies EB ≥ 15%, wherein a section of the belt layer located in the tire width direction in a width range of 10% of a width of a second-widest belt in the belt layer on the left and right sides of the tire equator line has a belt angle θc that satisfies 0.3 rad ≤ θc ≤ 0.6 rad, and the elongation at break EB of the carcass cord threads and the belt angle θc satisfy 800 < 1140 × θc + 20 × EB < 1400.

[0007] Furthermore, the tread section in the pneumatic tire g described above preferably comprises: a pair of central main grooves extending in the circumferential direction of the tire, wherein the tire equator line is arranged between the central main grooves, and a central rib section defined by the pair of central main grooves, wherein the rib section of the tread section, which is located in the width direction of the tire in the width range of 10% of the width of the second widest belt in the belt layer on the left and right sides of the tire equator line, has an average total thickness GC that satisfies 5 mm ≤ GC ≤ 10 mm, and wherein the average total thickness GC of a rib section of the tread section, the elongation at break EB of the carcass cord threads, and the belt angle θc 1300 ≤ 60 × GC + 1140 × θc + 20 × EB ≤ Fulfill 2000.

[0008] 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 %.

[0009] Furthermore, in the pneumatic tire described above, the carcass cord threads preferably have a standard fineness CF that meets 4000 dtex ≤ CF ≤ 8000 dtex.

[0010] Furthermore, in the pneumatic tire described above, the carcass cord threads preferably exhibit a twist coefficient CT after dip treatment that is CT ≥ 2000 (T / dm) × dtex 0,5 fulfilled. Advantageous effects of the invention

[0011] The pneumatic tire according to one embodiment of the present invention achieves the effect of providing both low rolling resistance and impact burst resistance in a compatible manner. List of characters 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 the pneumatic tires are mounted according to an embodiment of the present invention. Fig. Figure 3 is a diagram of a vehicle on which the pneumatic tires are mounted according to an embodiment of the present invention, viewed from the rear. Description of embodiments

[0012] 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 this embodiment. 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

[0013] Here, "tire radial direction" refers to the direction orthogonal to a tire rotation axis RX, which corresponds to the axis of rotation of a pneumatic tire 1. "Inner side in tire radial direction" refers to the side in the direction of the tire rotation axis RX in the tire radial direction. "Outer side 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 is orthogonal 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 the direction of tire width" refers to the side facing the tire equatorial plane (tire equator line) CL in the direction of tire width. The term "outside in the direction of tire width" refers to the side facing away from the tire equatorial plane CL in the direction of tire width. The tire width is the width in the direction of tire width between sections located on the outermost sides in the direction of tire width. In other words, the tire width is the distance between sections that are furthest from the tire equatorial plane CL in the direction of tire width.

[0014] 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 tire listed 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 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).

[0015] 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 Figure 3. Fig. 2 and Fig. The vehicle 500 shown in the illustration rotates around the tire rotation axis Rx.

[0016] 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 tire's circumferential direction and having a ring shape, is arranged at the outermost section in the tire's 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 travel 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's radial direction.

[0017] 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 specifies 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. It should be noted 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.

[0018] 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.

[0019] 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 22 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.

[0020] 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.

[0021] 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 is arranged on the inner side of each shoulder section 5 in the tire radial direction. In other words, the pair of sidewall sections 8 is arranged on both sides of the tread section 2 in the tire width direction. The sidewall sections 8 are thus formed from the outermost exposed sections of the pneumatic tire 1 in the tire width direction.

[0022] The bead sections 10 are each arranged on the inner side of the pair of sidewall sections 8 in the tire radial direction. 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 is 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 located on the outer side of the bead core 11 in the tire radial direction. 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 located on the outer side of the bead core 11 in the tire radial direction.

[0023] 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).

[0024] 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.

[0025] A belt cover 40 is located on the outer side of the belt layer 14 in the tire radial direction. The belt cover 40 is positioned on the outer side of the belt layer 14 in the tire radial direction, covers the belt layer 14 in the tire circumferential direction, 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 its outer side in the tire radial direction. 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 side of the belt cover 40 in the tread section 2 in the tire radial direction.

[0026] 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 inner side of the complete cover section 41 in the tire radial direction, and the other edge cover section 45 is located on the outer side of the complete cover section 41 in the tire radial direction.

[0027] 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 is arranged in a torus-shaped form between the pair of bead sections 10, which are arranged on both sides in the tire width direction and form the tire skeleton.

[0028] In particular, the carcass layer 13 is arranged such that it is positioned between one bead section 10 and 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 outer side 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 outer side 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.

[0029] Furthermore, a rim pad 17, forming a contact surface of the bead section 10 for a rim flange (not illustrated), is arranged on the inner side (in the tire radial direction) and on the outer side (in the tire width direction) of the bead core 11 and a folded-back section 131 (folded-back section) of the carcass layer 13 in the bead section 10. The pair of rim pad 17s extends from the inner side (in the tire radial direction) towards the outer side (in the tire width direction) of the left and right bead cores 11 and the folded-back sections 131 of the carcass layer 13 and forms rim mating surfaces of the bead sections 10. In addition, the belt layer 14 is located on the outer side (in the tire radial direction) of a section of the carcass layer 13 situated in the tread section 2, which is arranged between the pair of bead sections 10.

[0030] 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 then performing a rolling process on it. A plurality of carcass cord threads forming the carcass layers are arranged side by side at an angle in the tire's circumferential direction, the angle of which follows a meridional direction relative to the tire's circumference.

[0031] 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.

[0032] 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.

[0033] 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-ingress-preventing 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 the 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

[0034] 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.

[0035] 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.

[0036] 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.

[0037] “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.

[0038] "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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] “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 the pneumatic tire 1 is for a passenger car, the load is assumed to be 88% of the load.

[0043] 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.

[0044] In the following description, "inside in the direction of vehicle width" 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 direction of the vehicle 500's width. "Outside in the direction of vehicle width" 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 direction of the vehicle 500's width.

[0045] The present embodiment designates 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 with respect to the vehicle 500 is designated. The left pneumatic tire 1L is mounted on the left side of the vehicle 500 such that one designated sidewall section 8 of the pair of sidewall sections 8 faces the inner side in the direction of the vehicle's width, and the other sidewall section 8 faces the outer side in the direction of the vehicle's width. The right pneumatic tire 1R is mounted on the right side of the vehicle 500 such that one designated sidewall section 8 of the pair of sidewall sections 8 faces the inner side in the direction of the vehicle's width, and the other sidewall section 8 faces the outer side in the direction of the vehicle's width.

[0046] In a case where the mounting direction of the tire is specified with respect to the vehicle 500, the pneumatic tire 1 is provided with an indicator section 600 that indicates the specified 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 mark, 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.

[0047] The pneumatic tire 1 of the present embodiment meets the following conditions. The carcass cord threads have an elongation at break EB (%) that satisfies EB ≥ 15%. The elongation at break EB of the carcass cord threads is a physical property measured from sidewall sections of the pneumatic tire 1, i.e., the casing sections 131. Furthermore, the belts 141, 142, which are located in a width range of 10% (10% on the left and right sides, i.e., a total of 20%) of the width Wb2 of the second-widest belt (hereinafter referred to as the second belt) of the belt layer 14 in the tire width direction on the left and right sides of the tire equatorial plane CL, have a belt angle θc that satisfies 0.3 rad ≤ θc ≤ 0.6 rad. In other words, the belt angle θc satisfies 17° ≤ θc ≤ 34°.Furthermore, in the pneumatic tire with the conditions described above, the elongation at break EB (%) of the carcass cord threads and the belt angle θc (rad) preferably meet the following conditions. 800<1140×θc+20×EB < 1400

[0048] With the elongation at break EB (%) of the carcass cord threads and the belt angle θc satisfying the ranges described above, and with the elongation at break EB (%) of the carcass cord threads and the belt angle θc (rad) satisfying formula (1) described above, the pneumatic tire 1 can provide high performance in both low rolling resistance and impact burst strength in a compatible manner. In particular, with the belt angle θc in the region of the central rib section 20C within the range described above, the ground contact length is shortened to reduce rolling resistance, and the local deformation of an impact section is reduced to improve impact burst strength performance. Furthermore, with the elongation at break EB of the carcass cord threads within the range described above, the impact burst strength of the pneumatic tire 1 can be improved to suppress a reduction in the strength (stiffness) of the cord threads.Furthermore, fulfilling the formula (1) described above makes it possible to maintain the performance described above in a well-balanced manner.

[0049] 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, only belts 141 and 142 are illustrated; in other words, 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.

[0050] Furthermore, the carcass cord threads of the carcass layer 13 preferably have an elongation at break EB (%) that satisfies EB ≥ 20%. Additionally, the belt angle θc preferably satisfies 0.349 rad ≤ θc ≤ 0.56 rad and more preferably satisfies 0.384 rad ≤ θc ≤ 0.524 rad. In other words, the belt angle θc preferably satisfies 20° ≤ θc ≤ 32° and more preferably satisfies 22° ≤ θc ≤ 30°.

[0051] Furthermore, in the pneumatic tire 1, the tread rubber layer 4 of the central rib section 20C, which is located in the tire width direction within 10% (10% on the left and right sides, i.e. a total of 20%) of the width Wb2 of the second belt on the left and right sides of the tire equatorial plane CL, preferably has an average total thickness GC that satisfies 5 mm ≤ GC ≤ 10 mm, and the average total thickness GC of the central rib section 20C, the belt angle θc (rad) and the elongation at break EB of the carcass cord threads satisfy the following conditions. 1300<60×GC+1140×θc+20×EB(%)<2000

[0052] With the average total thickness GC, the belt angle θc (rad), and the elongation at break EB of the carcass cord thread, adjusted to meet the conditions described above, both the low rolling resistance and the impact burst strength of the pneumatic tire 1 can be provided in a compatible manner. The relationship described above more preferably satisfies 1350 < 60 × GC + 1140 × θc + 20 × EB (%) < 1950.

[0053] Furthermore, the carcass cord threads in the pneumatic tire 1 preferably have an intermediate elongation EM that satisfies EM ≤ 5.0% at a load of 1.0 cN / dtex (nominal fineness). Additionally, the carcass cord threads preferably have a nominal fineness NF that satisfies 3500 dtex ≤ NF ≤ 7000 dtex.

[0054] “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 cords 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”.

[0055] By reducing the intermediate elongation EM of the carcass cord threads while maintaining the tensile elongation EB of the carcass cord threads, the low rolling resistance of the pneumatic tire 1 can be improved without impairing the impact burst strength of the pneumatic tire 1.

[0056] Furthermore, after dip treatment, the carcass cord threads preferably have a standard fineness CF that meets 4000 dtex ≤ CF ≤ 8000 dtex. Additionally, after dip treatment, the carcass cord threads preferably have a standard fineness CF that meets 5000 dtex ≤ CF ≤ 7000 dtex.

[0057] “Standard quantity fineness of carcass cord threads after dip treatment” refers to the fineness measured on the carcass cord threads after dip treatment and is not a value for the carcass cord threads themselves, but a value that includes a dip fluid that adheres to the carcass cord threads after dip treatment.

[0058] If the standard quantity fineness CF of the carcass cord threads after dip treatment is 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, thus enabling both the low rolling resistance and the impact burst strength of the pneumatic tire 1 to be provided in a compatible manner.

[0059] 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.

[0060] If the twist coefficient CT of the carcass cord threads after dip treatment is 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 allows both the low rolling resistance and impact burst strength of the pneumatic tire 1 to be provided in a compatible manner. Furthermore, reducing the intermediate elongation EM of the carcass cord threads while preserving the elongation at break EB of the carcass cord threads makes the carcass cord threads easily stretchable and difficult to cut. Example

[0061] 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 for impact burst resistance and rolling resistance under different conditions. For the performance tests, pneumatic tires (test tires) of size 265 / 35ZR20 were mounted on 20 × 9.5 J rims, inflated to a pressure of 200 kPa, and fitted to a test passenger car, an FF sedan (total engine displacement of 1600 cm³). 3 ) mounted.

[0062] For the evaluation of impact burst strength, a piston test was performed according to FMVS139. The evaluation of impact burst strength was carried out using index values, with comparison example 1 assigned as the reference (100), where higher values ​​are more preferred.

[0063] In the performance tests relating to rolling resistance, the rolling resistance coefficients were calculated according to ISO 28580 at a load of 4.8 kN and a speed of 80 km / h. The result is expressed as an index, with the reciprocal of the rolling resistance coefficient from comparison example 1 assigned as the reference (100). Higher index values ​​indicate lower rolling resistance.

[0064] In the example in Table 1, the pneumatic tires in Comparison Examples 1 and 3 use high-stiffness rayon fiber cord threads as the carcass cord threads forming the carcass ply. In contrast, the pneumatic tires in Comparison Example 2 and Examples 1 and 2 use PET fiber cord threads, which have a higher elongation at break than rayon, as the carcass cord threads forming the carcass ply. Table 3 is a comparison table for rayon fiber cord threads and PET fiber cord threads. As illustrated in Table 3, the PET fiber cord threads, with an identical intermediate elongation to the carcass cord threads, exhibit a higher elongation at break and a higher standard thread count than the rayon fiber cord threads. Furthermore, the rayon fiber cord threads fatigue easily and therefore require a higher twist rate. Furthermore, in the example in Table 2, PET fiber cord threads were used in all pneumatic tires of examples 1 to 9.For the pneumatic tire of Example 1, which is used as a reference, the other conditions vary among the pneumatic tires of Examples 1 to 9. These pneumatic tires were evaluated for their impact burst strength and rolling resistance according to an evaluation procedure described below, and the results are shown in Tables 1 and 2. [Table 1] Comparative example 1 Comparative example 2 Comparative example 3 Example 1 Example 2 Type of organic fiber material Rayon PET Rayon PET PET Belt angle θc (rad) 0,524 0,524 0,349 0,436 0,436 Elongation at break EB (%) of the carcass cord threads 10 45 10 25 30 1140 × θc + 20 × EB 800 1500 600 1000 1100 Impact burst resistance 100 130 65 110 115 Rolling performance 100 100 105 103 103 [Table 2-1] Example 1 Example 2 Example 3 Example 4 Example 5 Type of organic fiber material PET PET PET PET PET Belt angle θc (rad) 0,524 0,436 0,436 0,436 0,436 Elongation at break EB (%) of the carcass cord threads 20 25 25 25 25 1140 × θc + 20 × EB 1000 1000 1000 1000 1000 Average total thickness GC 9,5 9,5 9,5 4 9,5 60 × GC + 1140 × θc + 20 × EB (%) 1570 1570 1570 1240 1570 Intermediate elongation EM (%) of the carcass cord threads 3 3 6 6 6 Standard quantity fineness CF of carcass cord threads 6400 9000 6400 9000 9000 Twist coefficient CT of the carcass cord threads 1500 2100 1500 1500 1500 Impact burst resistance 100 105 105 80 105 Rolling performance 100 103 103 107 103 [Table 2-II] Example 6 Example 7 Example 8 Example 9 Type of organic fiber material PET PET PET PET Belt angle θc (rad) 0,436 0,436 0,436 0,436 Elongation at break EB (%) of the carcass cord threads 25 25 25 25 1140 × θc + 20 × EB 1000 1000 1000 1000 Average total thickness GC 9,5 9,5 9,5 9,5 60 × GC + 1140 × θc + 20 × EB (%) 1570 1570 1570 1570 Intermediate elongation EM (%) of the carcass cord threads 3 3 3 3 Standard quantity fineness CF of carcass cord threads 9000 6400 6400 9000 Twist coefficient CT of the carcass cord threads 1500 1500 2200 2200 Impact burst resistance 105 105 105 105 Rolling performance 103 103 103 103 [Table 3] Image of physical properties Rayon PET Elongation at break EB (%) of the carcass cord threads Approximately 13% 22 to 28% Intermediate elongation EM (%) of the carcass cord threads 2 to 3% 2 to 3% Standard quantity fineness CF of carcass cord threads 6200 to 6300 dtex 6400 to 6500 dtex Twist coefficient CT of the carcass cord threads 2800 2100

[0065] As shown in Table 1, the pneumatic tires of Examples 1 and 2 achieved better rating results than the pneumatic tires of Comparison Examples 1 to 3. In other words, at least under conditions identical to those for the pneumatic tires of Examples 1 and 2, even when using PET fiber cord threads, rating results are obtained that are equivalent to or higher than those obtained when using rayon fiber cord threads. Additionally, as shown in Table 2, in the pneumatic tires of Examples 1 to 9, varying the conditions within predetermined ranges leads to more favorable rating results depending on the conditions. Reference symbol list 1 pneumatic tire 2. Tread section 3 Running surface contact surface 4 tread rubber layer 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 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 500 vehicles 501 Driving apparatus 502 Vehicle body 503 Engine 504 wheel 505 axle 506 Steering apparatus 507 Brake apparatus 600 indicator section QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2015231772 A

[0003] JP 2015231773 A

[0003]

Claims

[1] Pneumatic tires, including: a tread section that extends in a circumferential direction of the tire and has a ring 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 sections in the tire radial direction; at least one carcass layer arranged 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 comprises carcass cord threads formed from organic fiber cord threads obtained by interlacing a bundle of filaments of organic fibers, and The fold sections are formed by folding over the end sections of the pair of bead sections to an outer side in the direction of tire width. the carcass cord threads have an elongation at break EB that meets EB ≥ 15%, a section of the belt layer located within a width range of 10% of the width of the second widest belt in the belt layer on the left and right sides of a tire equator line (in the direction of tire width) has a belt angle θc that satisfies 0.3 rad ≤ θc ≤ 0.6 rad, and the elongation at break EB of the carcass cord threads and the belt angle θc 800 < 1140 × θc + 20 × EB < 1400 must be met. [2] Pneumatic tires according to claim 1, wherein the tread section comprises a pair of central main grooves extending in the circumferential direction of the tire, with the tire equator line positioned between the central main grooves, and a central rib section defined by the pair of central main grooves, the central rib section, which is located in the width range of 10% of the width of the second widest belt in the belt layer on the left and right sides of the tire equator line in the direction of tire width, has an average total thickness GC that meets 5 mm ≤ GC ≤ 10 mm, and the average total thickness GC of a rib section of the tread section, the elongation at break EB of the carcass cord threads and the belt angle θc 1300 ≤ 60 × GC + 1140 × θc + 20 × EB ≤ 2000 must be satisfied. [3] Pneumatic tire 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 satisfies EM ≤ 5.0 %. [4] Pneumatic tire according to any one of claims 1 to 3, wherein the carcass cord threads have a standard quantity fineness CF that meets 4000 dtex ≤ CF ≤ 8000 dtex. [5] Pneumatic tire according to any one of claims 1 to 4, wherein the carcass cord threads have a twist coefficient CT after dip treatment, which CT ≥ 2000 (T / dm) × dtex 0,5 fulfilled.