Pneumatic tire

Abstract

The pneumatic tire includes a carcass including at least one carcass ply formed by coating cords with rubber. A protective layer covering an end portion of the carcass ply includes a rubber-coated organic fiber cord layer. The organic fiber cord has the minimum diameter of the cord of the constituent member of the pneumatic tire. At least a portion of the organic fiber cord extends beyond an end of the carcass ply to the outside in the tire radial direction.

Description

Technical Field

[0001] The present disclosure relates to a pneumatic tire. Background Art

[0002] A pneumatic tire has a carcass composed of one or more carcass plies formed by a rubber coating of carcass cords. Since the rigidity of the tire rubber and the carcass cords is different, stress concentrates on the carcass cords (especially the cord ends) in the tire rubber, which sometimes causes cracks and thus leads to failures.

[0003] To address this problem, in order to relieve the stress concentration at the ends of the cords of the reinforcing member, some methods have been proposed to cover the ends of the cords of the reinforcing member with a protective layer formed by a rubber coating composed of rubber and fibers, or to dispose the protective layer along the ends of the cords (for example, see Patent Document 1).

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Utility Model Laid-Open No. 01-099702 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] The above technique can be applied to the ends of the carcass plies. However, in some cases, even with this method, the durability of the pneumatic tire has not been sufficiently improved. As a result of research, the present inventors have found that one of the reasons why the durability of the pneumatic tire has not been sufficiently improved is that the protective layer, especially the ends of its fibers, become new crack initiation points due to stress concentration.

[0009] In view of the above problems, an object of the present disclosure is to provide a pneumatic tire having improved durability.

[0010] Solutions to the Problems

[0011] The gist of the present disclosure is as follows.

[0012] (1) A pneumatic tire including a carcass composed of at least one carcass ply formed by rubber-coated carcass cords, wherein

[0013] a protective layer formed by a rubber coating of organic fiber cords is disposed to cover the ends of the carcass plies,

[0014] the organic fiber cords have the smallest diameter among all the cords of the components constituting the pneumatic tire, and

[0015] at least a part of the organic fiber cords extends beyond the ends of the carcass plies to the radially outer side of the tire.

[0016] As used herein, the "force at 5% elongation of the organic fiber cord" shall be determined by measuring the force applied when removing the protective layer from the pneumatic tire, taking out one organic fiber cord from the layer, and then elongating the organic fiber cord by 5% (in accordance with JIS L 1095:2010).

[0017] Here, the "distance" shall mean the shortest distance between the cords of the reinforcing layer and the organic fiber cord when measured in a direction perpendicular to the extending direction of the cords of the reinforcing layer in a cross-section in the tire width direction.

[0018] As used herein, the term "applicable rim" means a standard rim of applicable size (the measuring rim in the ETRTO Standard Manual and the design rim in the TRA Yearbook) described in or that may be described in the industrial standards effective in the tire production and use regions (such as the JATMA Yearbook of the JATMA (Japan Automobile Tire Manufacturers Association) in Japan, the Standard Manual of the ETRTO (European Tyre and Rim Technical Organization) in Europe, and the Yearbook of the TRA (Tire and Rim Association) in the United States) (that is, the above "applicable rim" includes existing sizes and future sizes to be listed in the above industrial standards. An example of "future sizes to be listed" is the sizes listed as "future developments" in the 2013 edition of the ETRTO). For sizes not listed in these industrial standards, the term "applicable rim" means a rim whose width corresponds to the bead width of the pneumatic tire. As used herein, the "specified internal pressure" means the air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel of applicable size and ply rating, as described in the above JATMA Yearbook and other industrial standards. In the case where the size is not listed in the above industrial standards, the "specified internal pressure" means the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for each vehicle on which the tire is mounted).

[0019] Effects of the Invention

[0020] According to the present disclosure, a pneumatic tire having improved durability can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a cross-sectional view in the tire width direction of a pneumatic tire according to an embodiment of the present disclosure.

[0022] Figure 2 is Figure 1 an enlarged view of the vicinity of the bead portion in

[0023] Figure 3 shows a first modification of the present embodiment.

[0024] Figure 4 shows a second modification of the present embodiment.

[0025] Figure 5 It is a schematic diagram and an enlarged view of the vicinity of the end of the carcass ply.

[0026] Figure 6 is a graph showing the relationship between the rigidity of the protective layer and the strain.

[0027] Figure 7 is a schematic diagram illustrating shear deformation caused by the relative positions of the cords in the reinforcement layer and the organic fiber cords.

[0028] Figure 8 This is a graph showing the relationship between the distance from the end of the carcass cord to the top position of the turn-back portion of the organic fiber cord and the crack speed near the end of the carcass cord.

[0029] Figure 9 This is a graph showing the relationship between the force when the organic fiber cord is elongated by 5% and the crack length near the end or the turned-back portion of the organic fiber cord.

[0030] Figure 10 is a graph showing the physical properties of two types of organic fiber cords.

[0031] Figure 11 is a graph showing the relationship between the overlap length of the cords and the organic fiber cords in the reinforcement layer and the crack length.

[0032] Figure 12 This is a third modified example of the present embodiment. DETAILED DESCRIPTION

[0033] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0034] Figure 1 1 is a cross-sectional view in the tire width direction of a pneumatic tire (hereinafter simply referred to as a tire) according to one embodiment of the present disclosure. Figure 1 Although only one half of the tire in the tire width direction having the tire equatorial plane CL as a boundary is shown, the other half also has the same structure.

[0035] Figure 1 The example of a heavy load tire (for trucks and buses) is shown, but the present disclosure may also be used with tires for various other uses, such as passenger car tires, aircraft tires, and mining tires.

[0036] The internal structure of the tire is not particularly limited, but as an example, Figure 1As shown, the tire 1 has: a carcass 3 that spans a pair of bead portions 2 in an annular shape; a belt 4 that is composed of one or more belt layers disposed radially outside the crown portion of the carcass 3; and a tread 5. A pair of sidewall portions 7 are connected between the pair of bead portions 2 and the tread 5.

[0037] In this example, a bead core 2a is embedded in each bead portion 2. Further, a bead filler 2b having a substantially triangular cross section is disposed radially outside the bead core 2a. The bead filler 2b may also be composed of a hard portion and a soft portion located radially outside the hard portion. A steel bead cover 6 is disposed around the bead core 2a (on the outer peripheral side of the carcass 3 when viewed from the bead core 2a).

[0038] The carcass 3 is composed of one or more carcass ply layers. The carcass ply layer is formed of carcass cords coated with rubber. The carcass cords are not particularly limited to any specific type and may be steel cords. The carcass 3 has: a carcass main body portion 3a that spans a pair of bead portions 2 in an annular shape; and a carcass turned-up portion 3b that extends from the carcass main body portion 3a and folds around the bead core 2a from the inner side to the outer side in the tire width direction. In the illustrated example, the end portion (the end portion of the carcass turned-up portion 3b) 3c of the carcass ply layer is located radially inside the tire, rather than in the tire width direction.

[0039] In the illustrated example, the belt 4 has four belt layers 4a to 4d. In the illustrated example, the belt layer 4a, the belt layer 4b, the belt layer 4c, and the belt layer 4d are arranged in this order from the radially inner side of the tire. In this example, the belt layer 4d has the smallest width in the tire width direction, and the belt layer 4b has the largest width in the tire width direction. Regardless of the above example, the number of belt layers and the widths of the belts in the tire width direction can have various configurations.

[0040] Further, each belt layer is made of a belt ply layer formed of belt cords coated with rubber. The belt cords are not limited to any specific type and may be steel cords. The belt cords extend in such a manner that the cords cross each other between the layers. Although not particularly limited, the inclination angle of the belt cords with respect to the tire circumferential direction may be 10° to 60°, and for heavy-duty tires, it may be 15° to 60°, preferably 30° to 60°.

[0041] The tread 5 is made of tread rubber. For example, the tread rubber may be composed of two or more layers laminated in the tire radial direction. The sidewall portion 7 is made of sidewall rubber.

[0042] Figure 2 is Figure 1 an enlarged view near the bead portion in. As Figure 1 and Figure 2As shown, in this tire 1, a protective layer 8 formed by rubber coating of organic fiber cords is arranged to cover the end 3c of the carcass ply. Figure 5 is a schematic view and an enlarged view near the end 3c of the carcass ply. In the illustrated example, the protective layer 8 is U-shaped. In other words, the protective layer 8 extends from the inner side in the tire radial direction to the outer side on the inner side in the tire width direction of the ply at the carcass folding portion 3b, folds back near the end 3c of the carcass ply, and extends from the outer side in the tire radial direction to the inner side on the outer side in the tire width direction of the ply at the carcass folding portion 3b, thereby covering the end 3c of the carcass ply and its vicinity. The organic fiber cords can be arranged in the form of a "Sudare" pattern, with the warp and weft crossing at approximately 90° inside the tire. However, the structure of the organic fiber cords is not limited to the "Sudare" pattern.

[0043] Figure 3 A first modification of this embodiment is shown. In this example, the protective layer 8 is arranged only on the outer side in the tire width direction of the carcass ply and extends from the inner side in the tire radial direction to the outer side beyond the end 3c of the carcass ply.

[0044] Figure 4 A second modification of this embodiment is shown. In this example, the protective layer 8 is arranged on both the inner side and the outer side in the tire width direction of the carcass ply and both extend from the inner side in the tire radial direction to the outer side beyond the end 3c of the carcass ply.

[0045] In this way, the protective layer 8 can cover the end 3c of the carcass ply in various ways on the outer side and / or the inner side in the tire width direction of the carcass folding portion 3b.

[0046] Figure 12 A third modification of this embodiment is shown. In this example, the protective layer 8 is U-shaped. In other words, the protective layer 8 extends from the inner side in the tire radial direction to the outer side on the inner side in the tire width direction of the ply at the carcass folding portion 3b, folds back outside the end 3c of the carcass ply, and extends from the outer side in the tire radial direction to the inner side on the outer side in the tire width direction of the ply at the carcass folding portion 3b, thereby covering the end 3c of the carcass ply and its vicinity.

[0047] In addition, the diameter of the organic fiber cords is between 0.04 mm and 0.60 mm. As the organic fiber, polyester, rayon, nylon, aramid, etc. can be used. In this example, the organic fiber cords have the smallest diameter among all the cords of the components constituting the tire 1 (in the tire components existing in any cross-section in the tire width direction).

[0048] Here, at least a part of the organic fiber cords extends beyond the end 3c of the carcass ply (in this example, the end 3c of the carcass folding portion 3b) to the outer side in the tire radial direction. In Figure 2In the example shown, the protective layer 8 is folded back on the tire radial direction outer side of the end portion of the carcass cord to cover the end portion of the carcass cord.

[0049] Next, the effects of the pneumatic tire of the present embodiment will be described.

[0050] The pneumatic tire 1 of the present embodiment includes a carcass 3 composed of at least one carcass ply formed of rubber-coated carcass cords, and a protective layer formed of a rubber coating of organic fiber cords is arranged to cover the end 3c of the carcass ply. This protects the end 3c of the carcass ply with the protective layer 8 and prevents failure from occurring near the end of the carcass ply.

[0051] Here, the closer the end of the carcass ply, the end of the organic fiber cord, or the vertex position of the turn-back portion of the organic fiber cord is to the rim flange portion of the bead portion 2, the greater the strain near the end of the carcass ply, the end of the organic fiber cord, or the vertex position of the turn-back portion of the organic fiber cord. This is because the rubber sandwiched between the rim flange portion and the turn-back portion 3b of the carcass ply is repeatedly deformed and moves radially outward during tire rolling. As a result, there is a concern that sufficient tire life will not be obtained. On the other hand, in the area further outward in the tire radial direction, the bending deformation at the contact area of ​​the bead portion 2 during tire rolling increases, and the strain near the end of the carcass ply, the end of the organic fiber cord, and the vertex position of the turn-back portion of the organic fiber cord increases.

[0052] In this regard, in the pneumatic tire 1 of the present embodiment, at least a portion of the organic fiber cord extends beyond the end 3c of the carcass ply (in this example, the end 3c of the carcass folded portion 3b) to the outside in the tire radial direction, so that the end 3c of the carcass ply can be positioned relatively close to the rim flange portion to reduce the influence of bending deformation, and at the same time, the end of the organic fiber cord or the vertex position of the folded portion of the organic fiber cord can be positioned away from the rim flange portion to reduce the influence of repeated deformation. Since the organic fiber cord has the smallest diameter among the cords constituting the components of the tire 1, its rigidity is low, and by adopting the above configuration, the effect of suppressing the occurrence of cracks can be effectively obtained by reducing strain concentration.

[0053] As described above, the pneumatic tire of the present embodiment can improve the durability of the tire.

[0054] Here, the shortest distance between the end of the organic fiber cord or the vertex position of the turned-back portion of the organic fiber cord and the end of the carcass ply is preferably 5 mm to 37 mm.

[0055] Figure 8This is a graph showing the relationship between the distance from the end of the carcass cord to the vertex position of the folded portion of the organic fiber cord and the crack velocity near the end of the carcass cord. A tire of size 275 / 80R22.5 was assembled on a rim of size 22.5×8.25J, and the internal pressure was set to 875kPa. The tire was driven for 30,000km under a load of 57.33kN, and then the crack length was measured. By setting the above shortest distance to 5mm to 37mm, it is estimated that the tire life can be improved by about 10%.

[0056] It is believed that by making the shortest distance 5 mm or greater and 37 mm or less, the end 3c of the carcass ply can be positioned closer to the rim flange portion, while the end of the organic fiber cord or the vertex position of the folded portion of the organic fiber cord can be positioned away from the rim flange portion, thereby effectively achieving the above-mentioned effect.

[0057] Here, the diameter of the organic fiber cord in the protective layer 8 is preferably 0.04 mm to 0.60 mm. Figure 6 is a graph showing the relationship between the rigidity of the protective layer and the strain (near the cord ends in the reinforcing layer and near the cord ends in the protective layer) (which gives the results of the prediction calculation). Figure 6 As shown in FIG. 1 , the higher the rigidity of the protective layer 8, the smaller the strain near the end of the carcass cord of the reinforcing layer to be protected (the carcass in this embodiment). On the other hand, when the rigidity of the protective layer 8 is high, the difference in rigidity with the rubber will be large, which will cause the end of the organic fiber cord in the protective layer 8 and the Figure 2 In the example of , a large strain is generated near the folded portion of the organic fiber cord in the protective layer 8. If the strain becomes too large and a crack develops in any of these areas, it will cause tire failure. Therefore, the optimal stiffness value of the organic fiber cord can be determined as the stiffness corresponding to the point where "the larger of the strain in the area near the cord end in the reinforcing layer and the strain in the area near the organic fiber cord end in the protective layer" is smaller, and the range around this point can be set to a suitable stiffness range. Here, among all the cords constituting the components of the pneumatic tire, the organic fiber cord has the smallest diameter, so it is possible to reduce the strain near the end of the organic fiber cord in the protective layer 8 and Figure 2 Strain near the foldback section in the example.

[0058] In particular, by setting the diameter of the organic fiber cord in the protective layer 8 to 0.04 mm or more, the strain near the end of the carcass cord to be protected can be reduced. On the other hand, by setting the diameter of the organic fiber cord in the protective layer 8 to 0.60 mm or less, the strain near the end of the organic fiber cord in the protective layer 8 and Figure 2The strain near the return portion in the example of. Therefore, by making the diameter of the organic fiber cord of the protective layer 8 between 0.04 and 0.60 mm, it is possible to suppress the strain near the end of the carcass cord and the strain near the end of the organic fiber cord of the protective layer 8 and Figure 2 the strain near the return portion in the example of, and it is possible to more reliably suppress the occurrence and progression of cracks.

[0059] The force when the organic fiber cord elongates by 5% is preferably 2 N to 10 N. Figure 9 is a graph showing the relationship between the force when the organic fiber cord elongates by 5% and the crack length near the end or return portion of the organic fiber cord. As Figure 9 shown, when the index (the smaller the index, the shorter the crack length) of the comparative example (a tire having a protective layer formed of an organic fiber that exerts a force of 41 N when elongated) is set to 1, it can be seen that when using an organic fiber cord with a force of 4 N when elongated by 5% ( Figure 10 fiber 1 in) or 10 N ( Figure 10 fiber 2 in), the crack length decreases. By setting the force when the organic fiber cord elongates by 5% to 10 N or less, it is possible to effectively reduce the strain near the end of the organic fiber cord in the protective layer 8 and Figure 2 the strain near the return portion shown in the example of. On the other hand, by setting the force when the organic fiber cord elongates by 5% to 2 N or more, it is possible to effectively reduce the strain near the end of the reinforcing layer. In Figure 9 , when the force when the organic fiber cord elongates by 5% is 2 N, it was confirmed that the cracks were suppressed by about 10%.

[0060] In addition, it is preferable that the number of organic fiber cords per unit width is greater than the number of carcass cords per unit width, and the distance between adjacent organic fiber cords is 0.1 mm or more. By increasing the number of organic fiber cords per unit width compared to the number of carcass cords per unit width, the strain near the end of the carcass ply can be further reduced. On the other hand, by ensuring that the distance between adjacent organic fiber cords is 0.1 mm or more, the distance between the fibers is maintained and the stress intensity factor does not increase, which helps prevent the occurrence of cracks.

[0061] Figure 7 is a schematic diagram illustrating the shear deformation caused by the relative position of the carcass cord and the organic fiber cord. As Figure 7 schematically shown, the greater the distance between the carcass cord and the organic fiber cord, the greater the shear deformation (schematically shown by two parallelograms of different sizes).

[0062] Therefore, under the above-mentioned reference conditions, the distance between the carcass cord and the organic fiber cord is preferably 0.2 mm to 1.0 mm. This is because reducing the distance to 1.0 mm or less can reduce shear deformation and further improve the durability of the tire. On the other hand, although there is no particular limitation, from a manufacturing perspective, the above-mentioned distance is preferably 0.2 mm or more. It should be noted that when the above-mentioned distance is set to 1.0 mm, the indoor test results show that the tire life is increased by 10% compared with a tire having a protective layer formed of an organic fiber that exerts a force of 41 N when stretched.

[0063] In addition, as Figure 7 shown, the longer the overlapping width between the carcass cord and the organic fiber cord (the overlapping width along the extending direction of the cords in the reinforcing layer), the smaller the shear deformation. Therefore, under the above-mentioned reference conditions, the overlapping width between the carcass cord and the organic fiber cord is preferably 10 mm or more. A tire with a tire size of 275 / 80R22.5 is mounted on a rim with a rim size of 22.5×8.25J, and the tire is inspected after traveling 30,000 km under an internal pressure of 875 kPa and a load of 57.33 kN. Figure 11 is a graph showing the relationship between the overlapping width of the cords in the reinforcing layer and the organic fiber cord and the crack length near the end of the reinforcing layer. As Figure 11 shown, when the overlapping width is 10 mm or more, the effect is confirmed. On the other hand, although there is no particular limitation, even if the overlapping width is increased to 17 mm or more, the effect will saturate. Therefore, from the perspective of reducing the number of components and manufacturing deviations, the overlapping width is preferably set to 17 mm to 30 mm.

[0064] In addition, regarding the angle formed between the cords of the reinforcing layer and the organic fiber cord, from a manufacturing perspective, preferably, the angle formed between the cords of the reinforcing layer and the organic fiber cord extending in the direction with a larger number of cords per unit width among the organic fiber cords extending along two intersecting directions is less than 10°, or the angle formed between the cords of the reinforcing layer and the organic fiber cord extending in the direction with a smaller number of cords per unit width among the organic fiber cords extending along two intersecting directions is less than 10°.

[0065] The tire may include an RF tag as the communication device 100. The RF tag includes an IC chip and an antenna. For example, the RF tag may be arranged by being sandwiched between a plurality of same-type or different-type components that constitute the tire. This makes it easier to install the RF tag during the tire manufacturing process and improves the productivity of the tire including the RF tag. In this example, the RF tag may be arranged by being sandwiched between the bead filler and other components adjacent to the bead filler. The RF tag may be embedded in any component that constitutes the tire. Compared with arranging the RF tag by sandwiching it between a plurality of components that constitute the tire, the load applied to the RF tag can be reduced. This improves the durability of the RF tag. In this example, the RF tag may be embedded in rubber components such as tread rubber and sidewall rubber. Preferably, the RF tag is not arranged at the boundary position between components with different rigidity levels in the circumferential direction, which is the direction along the outer surface of the tire in the cross-sectional view in the tire width direction. In this way, the RF tag is not arranged at a position where strain concentration is likely to occur due to the rigidity gap. Therefore, the load applied to the RF tag can be reduced. This improves the durability of the RF tag. In this example, preferably, the RF tag is not arranged at the boundary between the carcass end and the component (such as sidewall rubber) adjacent to the carcass end in the cross-sectional view in the tire width direction. The number of RF tags is not particularly limited. The tire may include only one RF tag or may include two or more RF tags. Here, the RF tag is described as an example of the communication device, but a communication device other than the RF tag may also be used.

[0066] For example, the RF tag may be arranged on the tread portion of the tire. In this way, the RF tag will not be damaged due to the lateral cut of the tire. For example, the RF tag may be arranged at the center in the tire width direction of the tread portion. The center of the tread is a position where flexure does not concentrate in the tread portion. In this way, the load applied to the RF tag can be reduced. This improves the durability of the RF tag. In addition, this also prevents the tire from having a difference in communication performance between the RF tags on the two outer sides in the tire width direction. In this example, the RF tag may be arranged within, for example, a range of 1 / 2 of the tread width in the tire width direction centered on the tire equatorial plane. For example, the RF tag may be arranged at the tread end in the tire width direction. If the position of the reader that communicates with the RF tag is predetermined, the RF tag may be arranged, for example, at the tread end on the side closer to the reader. In this example, the RF tag may be arranged within, for example, a range of 1 / 4 of the tread width in the tire width direction with the tread end as the outer end.

[0067] For example, the RF tag can be arranged closer to the tire cavity than the carcass, which includes one or more carcass plies spanning the bead portions. In this way, the RF tag is not easily damaged by external impacts on the tire (such as side cuts and punctures, etc.). As an example, the RF tag can be arranged in close contact with the surface on the tire cavity side of the carcass. As another example, when there is another component closer to the tire cavity than the carcass, the RF tag can be arranged, for example, between the carcass and this other component closer to the tire cavity than the carcass. An example of another component closer to the tire cavity than the carcass is the inner liner forming the inner surface of the tire. As another example, the RF tag can be attached to the inner surface of the tire facing the tire cavity. With the structure of having the RF tag attached to the inner surface of the tire, it is easy to attach the RF tag to the tire and to inspect and replace the RF tag. In other words, the convenience of attaching and maintaining the RF tag can be improved. In addition, compared with the structure of embedding the RF tag inside the tire, by attaching the RF tag to the inner surface of the tire, it can be prevented that the RF tag becomes the core of tire failure. In addition, when the carcass has multiple carcass plies and there are positions where multiple carcass plies overlap each other, the RF tag can be arranged between the overlapping carcass plies.

[0068] For example, the RF tag can be arranged in the tread area of the tire on the tire radially outer side of a belt including one or more belt plies. As an example, the RF tag can be arranged on the tire radially outer side of the belt and in close contact therewith. As another example, when a reinforcing belt layer is provided, the RF tag can be arranged on the tire radially outer side of the reinforcing belt layer and in close contact therewith. As yet another example, the RF tag can be embedded in the tread rubber on the tire radially outer side of the belt. By arranging the RF tag in the tread area of the tire on the tire radially outer side of the belt, communication with the RF tag from the radially outer side of the tire is less likely to be interfered with by the belt. This improves the communication performance with the RF tag from the radially outer side of the tire. In addition, the RF tag can be embedded in the tread rubber on the tire radially inner side of the belt. In this way, the tire radially outer side of the RF tag is covered by the belt, so the RF tag is less likely to be damaged by impacts on the tread surface or nail insertions. As this example, the RF tag can be arranged between the belt and the carcass located on the tire radially inner side of the belt. In addition, when the belt includes multiple belt plies, the RF tag can be arranged between any two belt plies in the tread area of the tire. In this way, the tire radially outer side of the RF tag is covered by one or more belt plies, so the RF tag is less likely to be damaged by impacts on the tread surface or nail insertions.

[0069] For truck and bus tires, the RF tag can be arranged, for example, between the buffer rubber and the tread rubber, or between the buffer rubber and the sidewall rubber. In this way, the buffer rubber can reduce the impact on the RF tag. This improves the durability of the RF tag. In addition, for example, the RF tag can be embedded in the buffer rubber. In addition, the buffer rubber can be composed of a plurality of rubber members of the same or different types adjacent to each other. In this case, the RF tag can be arranged by being sandwiched between the plurality of rubber parts constituting the buffer rubber.

[0070] The RF tag can be arranged at a position, for example, in the sidewall portion or the bead portion of the tire. For example, the RF tag can be arranged on the sidewall portion or the bead portion on the side closer to the reader that can communicate with the RF tag. In this way, the communication performance between the RF tag and the reader can be improved. As an example, the RF tag can be arranged between the carcass and the sidewall rubber or between the tread rubber and the sidewall rubber. For example, the RF tag can be arranged in the tire radial direction between the position where the tire has the maximum width and the position of the tread surface. In this way, compared with the structure in which the RF tag is arranged on the inner side in the tire radial direction at the maximum width position of the tire, the communication performance with the RF tag from the outer side in the tire radial direction of the tire can be improved. For example, the RF tag can be arranged on the inner side in the tire radial direction at the maximum width position of the tire. In this way, the RF tag is arranged near the bead portion with higher rigidity. Therefore, the load applied to the RF tag is reduced, thereby improving the durability of the RF tag. As an example, the RF tag can be arranged at a position adjacent to the bead core in the tire radial direction or the tire width direction. The area around the bead core is not easily subjected to strain. Therefore, the load applied to the RF tag is reduced, thereby improving the durability of the RF tag. In particular, preferably, the RF tag is arranged on the inner side in the tire radial direction at the maximum width position of the tire and on the outer side in the tire radial direction of the bead core in the bead portion. In this way, the durability of the RF tag can be improved, and at the same time, the communication between the RF tag and the reader is less likely to be interfered by the bead core, thereby improving the communication performance of the RF tag. In addition, when the sidewall rubber is composed of a plurality of rubber parts of the same or different types adjacent to each other in the tire radial direction, the RF tag can be arranged by being sandwiched between the plurality of rubber parts constituting the sidewall rubber.

[0071] For a passenger car tire, the RF tag can be arranged by being sandwiched between the bead filler and a component adjacent to the bead filler. In this way, the RF tag can be arranged at a position where strain concentration is less likely to occur due to the configuration of the bead filler. Therefore, the load applied to the RF tag is reduced, thereby improving the durability of the RF tag. For example, the RF tag can be arranged by being sandwiched between the bead filler and the carcass. The portion of the carcass that holds the RF tag and the bead filler in place can be located outside the tire width direction with respect to the bead filler, or can be located inside the tire width direction with respect to the bead filler. When the portion of the carcass that holds the RF tag and the bead filler in place is located outside the tire width direction of the bead filler, the load applied to the RF tag due to an impact or damage to the tire from the outside in the tire width direction of the tire can be further reduced. This can further improve the durability of the RF tag. In addition, the bead filler can have a portion adjacent to the sidewall rubber. In this case, the RF tag can be arranged by being sandwiched between the bead filler and the sidewall rubber. In addition, the bead filler can also have a portion adjacent to the rubber chafer. In this case, the RF tag can be arranged by being sandwiched between the bead filler and the rubber chafer.

[0072] For truck and bus tires, the RF tag can be disposed between the reinforcement and a component adjacent to the reinforcement. In this way, the RF tag can be disposed at a position where strain concentration is less likely to occur due to the placement of the reinforcement. Accordingly, the load applied to the RF tag is reduced, thereby improving the durability of the RF tag. For example, the RF tag can be disposed by being sandwiched between the reinforcement and the sidewall rubber. Alternatively, the RF tag can also be disposed by being sandwiched between the reinforcement and the carcass. The portion of the carcass that holds the RF tag and the reinforcement in place can be located outside the tire width direction with respect to the reinforcement or inside the tire width direction with respect to the reinforcement. When the portion of the carcass that holds the RF tag and the reinforcement in place is located outside the tire width direction with respect to the reinforcement, the load applied to the RF tag due to an impact or damage to the tire from the outside in the tire width direction of the tire can be further reduced. This can further improve the durability of the RF tag. The reinforcement can also include a portion disposed adjacent to the rubber chafer. In this case, the RF tag can be disposed by being sandwiched between the reinforcement and the rubber chafer. The reinforcement can include a portion adjacent to the crown rubber outside the tire width direction. In this case, the RF tag can be disposed by being sandwiched between the reinforcement and the crown rubber. The reinforcement can be composed of a plurality of rubber components with different hardnesses. In this case, the RF tag can be disposed by being sandwiched between the plurality of rubber components that make up the reinforcement. The RF tag can be disposed by being sandwiched between the crown rubber and a component adjacent to the crown rubber. For example, the RF tag can be disposed by being sandwiched between the crown rubber and the carcass ply. In this way, the impact on the RF tag can be mitigated by the crown rubber, thereby improving the durability of the RF tag.

[0073] The RF tag can be disposed, for example, between the rubber chafer and the sidewall rubber. In this way, the RF tag can be disposed at a position where strain concentration is less likely to occur due to the placement of the rubber chafer. This reduces the load applied to the RF tag and improves the durability of the RF tag. The RF tag can be disposed, for example, by being sandwiched between the rubber chafer and the carcass. In this way, the load applied to the RF tag due to an impact or damage to the rim can be reduced. This improves the durability of the RF tag.

[0074] For truck and bus tires, the RF tag can be arranged by being sandwiched between the nylon chafer and another component adjacent to the outer or inner side of the nylon chafer in the tire width direction. In this way, when the tire deforms, the position of the RF tag is less likely to change. This reduces the load applied to the RF tag when the tire deforms, thereby improving the durability of the RF tag. For example, the nylon chafer may include a portion adjacent to the rubber chafer on the outer side in the tire width direction. In this case, the RF tag can be arranged by being sandwiched between the nylon chafer and the rubber chafer. For example, the nylon chafer may include a portion adjacent to the sidewall rubber on the outer side in the tire width direction. In this case, the RF tag can be arranged by being sandwiched between the nylon chafer and the sidewall rubber. For example, the nylon chafer may have a portion adjacent to the reinforcement on the inner side in the tire width direction. In this case, the RF tag can be arranged by being sandwiched between the nylon chafer and the reinforcement. In addition, for example, the nylon chafer may include a portion adjacent to the crown rubber on the inner side in the tire width direction. In this case, the RF tag can be arranged by being sandwiched between the nylon chafer and the crown rubber. In addition, the nylon chafer may include a portion adjacent to the carcass on the inner side in the tire width direction. In this case, the RF tag can be arranged by being sandwiched between the nylon chafer and the carcass. In addition, the nylon chafer may include a portion adjacent to the steel chafer on the inner side in the tire width direction. In this case, the RF tag can be arranged by being sandwiched between the nylon chafer and the steel chafer. In this way, the RF tag can be arranged by being sandwiched between the nylon chafer and another component adjacent to the nylon chafer on the outer or inner side in the tire width direction. In particular, when the outer side of the RF tag in the tire width direction is covered with the nylon chafer, the load applied to the RF tag due to impact or damage on the outer side of the tire in the tire width direction can be further reduced. This makes it possible to further improve the durability of the RF tag.

[0075] The RF tag can be arranged by being sandwiched between the steel chafer and another component adjacent to the steel chafer on the inner or outer side in the tire width direction. In this way, when the tire deforms, the position of the RF tag is less likely to change. This reduces the load applied to the RF tag when the tire deforms. This improves the durability of the RF tag. Another component adjacent to the steel chafer on the inner or outer side in the tire width direction may be a rubber member, such as a rubber chafer. Another component adjacent to the steel chafer on the inner or outer side in the tire width direction may be the carcass.

[0076] For passenger car tires, a belt reinforcing layer can be provided on the radially outer side of the belt. For example, the belt reinforcing layer can be formed of cords made of polyethylene terephthalate continuously spirally wound along the tire circumference. The cords are formed by being wound at 6.9×10-2 It is made by applying an adhesion treatment under a tension of N / tex or higher, and the elastic modulus under a load of 29.4 N measured at 160 °C can be 2.5 mN / tex% or higher. In addition, the belt reinforcing layer can be arranged to cover the entire belt, or can be arranged to cover only both ends of the belt. In addition, the winding density per unit width of the belt reinforcing layer can vary according to the position in the width direction. In this way, road noise and flat spots can be reduced without reducing high-speed durability.

[0077] Examples

[0078] To verify the effectiveness of the pneumatic tire of the present disclosure, test tires were manufactured and their tire life was evaluated through an indoor durability test. Each tire is provided with a protective layer formed by a rubber coating of organic fiber cord, covering the ends of at least one carcass ply formed by carcass cords coated with rubber. The specifications and evaluation results of each tire are provided in Table 1 below. The indoor durability test was carried out as follows: using a tire with a size of 275 / 80R22.5, a load of 37.19 kN, a driving distance of 100,000 km, an internal pressure of 900 kPa, and a rim size of 22.5×7.5J. As a comparative example, a test tire was manufactured, which is provided with a protective layer formed by an organic fiber that applies a force of 41 N when stretched. The evaluation results are provided as an index with the comparative example being "1". The smaller the value, the smaller the crack length near the end of the reinforcing layer, and the higher the durability of the tire.

[0079] [Table 1]

[0080]

[0081] As can be seen from Table 1, it is obvious that the tire durability of the example tire is improved compared to the comparative example. In addition, when the protective layer has a folded-back portion, no cracks appear near the end and the folded-back portion of the protective layer.

[0082] [Contribute to the United Nations-led Sustainable Development Goals (SDGs)]

[0083] The SDGs were proposed to achieve a sustainable society. One embodiment of the present disclosure is considered to be a technology that can contribute to "No. 12 - Ensure sustainable consumption and production patterns" and "No. 13 - Take urgent action to combat climate change and its impacts".

[0084] List of reference numerals

[0085] 1 Tire

[0086] 2 Bead portion

[0087] 3 Carcass

[0088] 4 Belt

[0089] 5 Tread

[0090] 6 Steel wire chafer

[0091] 7 Sidewall

[0092] 8 Protective layer

[0093] 100 Communication device

[0094] CL Tire equatorial plane

Claims

1. A pneumatic tire includes a carcass composed of at least one carcass ply formed of rubber-coated carcass cords, wherein a protective layer formed of a rubber coating of organic fiber cords is arranged to cover an end portion of the carcass ply, the organic fiber cords have the smallest diameter among all the cords of the components constituting the pneumatic tire, and at least a part of the organic fiber cords extends beyond the end portion of the carcass ply to the radially outer side of the tire.

2. The pneumatic tire according to claim 1, further including a pair of bead portions, the carcass has a carcass main body portion that extends across the pair of bead portions in an annular shape, and a carcass return portion that extends from the carcass main body portion and turns back around a bead core, and at least a part of the organic fiber cords extends beyond the end portion of the carcass return portion to the radially outer side of the tire.

3. The pneumatic tire according to claim 1 or 2, wherein a shortest distance between an end portion of the organic fiber cords or a vertex position of a return portion of the organic fiber cords and an end portion of the carcass ply is 5 mm to 37 mm.

4. The pneumatic tire according to any one of claims 1 to 3, wherein a force when the organic fiber cords are elongated by 5% is 2 N to 10 N.

5. The pneumatic tire according to any one of claims 1 to 4, wherein a number of the organic fiber cords per unit width is larger than a number of the carcass cords per unit width, and a spacing between adjacent organic fiber cords is 0.1 mm or more.

6. The pneumatic tire according to any one of claims 1 to 5, wherein under a reference condition where the pneumatic tire is mounted on an applicable rim, filled with a specified internal pressure, and unloaded, a distance between the carcass cords and the organic fiber cords is 0.2 mm to 1.0 mm.

7. The pneumatic tire according to any one of claims 1 to 6, wherein under a reference condition where the pneumatic tire is mounted on an applicable rim, filled with a specified internal pressure, and unloaded, an overlapping width between the carcass cords and the organic fiber cords is 10 mm or more.

8. The pneumatic tire according to any one of claims 1 to 7, wherein the protective layer turns back on the radially outer side of an end portion of the carcass cords to cover the end portion of the carcass cords.

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