Pneumatic tire

Abstract

A pneumatic tire according to the present invention includes a belt composed of two or more inclined belt layers formed by rubber-coated belt cords crossing each other between layers. A protective layer made of a rubber coating layer of organic fiber cords is arranged to cover an end portion of a narrow-width inclined belt layer having a shorter width in a tire width direction among two adjacent inclined belt layers. The protective layer is folded back at the end of the narrow-width inclined belt layer and thus extends on the outside and inside of the narrow-width inclined belt layer in the tire radial direction. The organic fiber cords have the minimum diameter of all cords in the components of the pneumatic tire, and the length of the protective layer along the narrow-width inclined belt layer in a cross-sectional view in the tire width direction is greater on the inside of the narrow-width inclined belt layer in the tire radial direction than on the outside of the narrow-width inclined belt layer 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 belt composed of a rubber coating of belt cords. Due to the difference in rigidity between the tire rubber and the cords, stress concentrates on the cords (especially the cord ends) in the tire rubber, which sometimes causes cracks and leads to failures.

[0003] To address this problem, in order to relieve the stress concentration at the belt ends, some methods have been proposed to cover the ends of the belt cords with a protective layer formed of a rubber coating composed of rubber and fibers, or to dispose the protective layer along the ends of the belt 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] However, in some cases, even with the above methods, 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 for the insufficient improvement in the durability of the pneumatic tire is that the protective layer, especially the fiber ends thereof, becomes a new crack initiation point 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] Means for Solving the Problems

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

[0012] (1) A pneumatic tire including a belt composed of two or more inclined belt layers formed of rubber-coated belt cords that cross each other between layers, wherein

[0013] a protective layer formed of a rubber coating of organic fiber cords is disposed to cover the ends of the narrow-width inclined belt layer having a shorter width in the tire width direction among two adjacent inclined belt layers,

[0014] the protective layer turns back at the ends of the narrow-width inclined belt layer so that the protective layer extends on the radially outer side and the radially inner side of the narrow-width inclined belt layer,

[0015] The organic fiber cord has the smallest diameter among all the cords of the components constituting the pneumatic tire, and

[0016] Regarding the length of the protective layer along the narrow-width inclined belt layer in the cross-sectional view in the tire width direction, the length on the tire radial inner side of the narrow-width inclined belt layer is longer than the length on the tire radial outer side of the narrow-width inclined belt layer.

[0017] As used herein, the above-mentioned "width" or "length" in the tire width direction shall refer to the tire dimensions when the pneumatic tire is mounted on the applicable rim, filled with the specified internal pressure and without load.

[0018] In addition, "two adjacent inclined belt layers" means that the inclined belts are adjacent to each other. For example, even if there is a circumferential belt layer composed of reinforcing cords extending in the tire circumferential direction between the two inclined belt layers, these two inclined belt layers are considered adjacent to each other.

[0019] Furthermore, the "length of the protective layer along the narrow-width inclined belt layer in the cross-sectional view in the tire width direction" refers to the overlapping width between the protective layer and the narrow-width inclined belt layer in the cross-sectional view in the tire width direction.

[0020] As used herein, the "force when the organic fiber cord is elongated by 5%" shall be determined by measuring the force applied when the protective layer is removed from the pneumatic tire, one organic fiber cord is taken out from this layer, and then this organic fiber cord is elongated by 5% (in accordance with JIS L 1095:2010).

[0021] Here, the "distance" shall refer to the shortest distance between the belt cord and the organic fiber cord when measured in a direction perpendicular to the extending direction of the belt cord in the cross-sectional view in the tire width direction.

[0022] As used herein, the term "applicable rim" refers to a standard rim of applicable dimensions (the measuring rim in the ETRTO Standard Manual and the design rim in the TRA Yearbook) recorded or that may be recorded in industry standards effective in the regions where tires are produced and used (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 dimensions and future dimensions to be listed in the above industry standards. An example of "future dimensions to be listed" is the dimensions listed as "future developments" in the 2013 edition of the ETRTO). For dimensions not listed in these industry standards, the term "applicable rim" refers to a rim having a width corresponding to the bead width of the pneumatic tire. As used herein, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel of applicable dimensions and ply rating, as recorded in the above JATMA Yearbook and other industry standards. In the case where dimensions are not listed in the above industry standards, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for each vehicle on which the tire is mounted).

[0023] Effects of the Invention

[0024] According to the present disclosure, a pneumatic tire having improved durability can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a cross-sectional view of a pneumatic tire in the tire width direction according to an embodiment of the present disclosure.

[0026] Figure 2 is Figure 1 an enlarged view of the vicinity of the belt in

[0027] Figure 3 is a graph showing the relationship between the rigidity and strain of the protective layer.

[0028] Figure 4 is a hypothetical plan view of a narrow-width inclined belt layer and a protective layer as viewed from the radially outer side of the tire.

[0029] Figure 5 is a graph showing the relationship between the length along the narrow-width inclined belt layer and the crack length of the protective layer.

[0030] Figure 6 is a schematic view illustrating shear deformation caused by the relative positions of cords and organic fiber cords in the reinforcing layer.

[0031] Figure 7 is a graph showing the physical properties of two organic fiber cords.

[0032] Figure 8 It 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 the folded-back part of the organic fiber cord. Detailed implementation manners

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

[0034] Figure 1 It is a cross-sectional view of a pneumatic tire (hereinafter simply referred to as a tire) in the tire width direction according to an implementation manner of the present disclosure. Figure 1 Only one half of the tire in the tire width direction with the tire equatorial plane CL as the boundary is shown, but the other half also has the same structure.

[0035] Figure 1 An example of a heavy-duty tire (for trucks and buses) is shown, but the present disclosure can also be used for tires for various other purposes, 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, as Figure 1 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 in the tire. 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 wrapper 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 by 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 folded-back 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 folded-back portion 3b) 3c of the carcass ply layer is located radially inside the tire, rather than at a position 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 width of the belt in the tire width direction can have various configurations.

[0040] In addition, each belt layer is made of a belt ply formed by belt cords coated with rubber. The belt cords are not limited to any specific type and can be steel cords. The belt cords extend in such a way 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 can be 10° to 60°, and for heavy-duty tires, it can be 15° to 60°, preferably 30° to 60°.

[0041] The tread 5 is made of tread rubber. For example, the tread rubber can 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 of the belt region in. As Figure 1 and Figure 2 shown, in this tire 1, a protective layer 8 formed by a rubber coating of organic fiber cords is arranged to cover the end portion of the narrow-width inclined belt layer 4c having a shorter width in the tire width direction among two adjacent inclined belt layers 4b and 4c. In the illustrated example, the protective layer 8 is U-shaped. In other words, the protective layer 8 turns back at the end portion of the narrow-width inclined belt layer 4c, so that the protective layer 8 extends on the radially outer side and the inner side of the narrow-width inclined belt layer 4c. More specifically, the protective layer 8 extends from the inner side in the tire width direction to the outer side on the radially inner side of the narrow-width inclined belt layer 4c, turns back near the end portion of the narrow-width inclined belt layer 4c, and then extends from the outer side in the tire width direction to the inner side on the radially outer side of the narrow-width inclined belt layer 4c. The organic fiber cords can be arranged in the form of a "Sudare" pattern, and the warp and weft cross at about 90° inside the tire. However, the configuration of the organic fiber cords is not limited to the "Sudare" pattern.

[0043] The diameter of the organic fiber cords is the smallest among all the cords of the components constituting the pneumatic tire. The diameter of the organic fiber cords is preferably between 0.04 mm and 0.60 mm. As the organic fiber, polyester, rayon, nylon, aramid, etc. can be used.

[0044] Regarding the length of the protective layer 8 along the narrow-width inclined belt layer 4c in the cross-sectional view in the tire width direction, the length on the tire radial inner side of the narrow-width inclined belt layer 4c is longer than the length on the tire radial outer side of the narrow-width inclined belt layer 4c.

[0045] The effects of the pneumatic tire of the present embodiment will be described below.

[0046] In the pneumatic tire 1 of the present embodiment, a protective layer 8 formed by rubber coating of organic fiber cords is arranged to cover the end portion of the narrow-width inclined belt layer 4c having a shorter width in the tire width direction among two adjacent inclined belt layers 4b and 4c. According to this configuration, the protective layer 8 protects the end portion of the narrow-width inclined belt layer 4c and can suppress failures occurring near the end portion of the narrow-width inclined belt layer 4c.

[0047] Figure 3 is a graph showing the relationship between the rigidity and strain of the protective layer (t is the predicted calculation result). As Figure 3 shown, the higher the rigidity of the protective layer 8, the smaller the strain near the end of the belt cord of the belt layer to be protected. On the other hand, when the rigidity of the protective layer 8 is high, the difference in rigidity from the rubber will be large, which will cause large strains to appear near the end of the organic fiber cords in the protective layer 8 and Figure 2 near the folded-back portion of the protective layer 8 in the example shown. Therefore, in the pneumatic tire 1 of the present embodiment, the diameter of the organic fiber cords of the protective layer 8 is the smallest among all the cords of the components constituting the pneumatic tire, so that the strains near the end of the organic fiber cords in the protective layer 8 and Figure 2 near the folded-back portion in the example shown can be reduced.

[0048] Incidentally, among adjacent inclined belt layers, near the end of the narrow-width inclined belt layer 4c having a shorter width in the tire width direction, the strain of the crack causing fracture occurs on the tire radial inner side of the end of the narrow-width inclined belt layer 4c. Therefore, by making the length on the tire radial inner side (along the narrow-width inclined belt layer 4c) relatively long, the occurrence and development of cracks can be effectively suppressed. Figure 4 is a hypothetical plan view of the narrow-width inclined belt layer and the protective layer seen from the tire radial outer side. Since, as described above, the strain on the tire radial inner side of the narrow-width inclined belt layer 4c is large, it is preferable that the extending direction of the organic fiber cords of the protective layer 8 located on the tire radial inner side of the narrow-width inclined belt layer 4c follows the extending direction of the belt cords of the narrow-width inclined belt layer 4c. On the other hand, when such organic fiber cords are folded back at the end of the narrow-width inclined belt layer 4c, as Figure 4Schematically shown, the organic fiber cord and the belt cord cross each other. During tire manufacturing, when assembling the respective components while the protective layer has been positioned on the narrow-width inclined belt layer 4c, a cutter or a similar tool is used to cut the narrow-width inclined belt layer 4c into a fixed length along the belt cord of the belt layer, and at the same time, the organic fiber cord must also be cut ( Figure 4 An example of the cutting surface is shown by the symbol A in

[0049] ). Therefore, by making the length of the protective layer (along the narrow-width inclined belt layer) located radially outside the tire of the narrow-width inclined belt layer 4c relatively short, the burden on the manufacturer can be reduced. From this perspective, in the present embodiment, regarding the length of the protective layer 8 along the narrow-width inclined belt layer 4c in the tire width direction cross-sectional view, the length on the radially inner side of the tire of the narrow-width inclined belt layer 4c is greater than the length on the radially outer side of the tire of the narrow-width inclined belt layer 4c. It should be noted that if the organic fiber cord is bent into a V shape or the like, even on the radially outer side of the tire of the narrow-width inclined belt layer 4c, the extending direction of the organic fiber cord of the protective layer 8 can be made to coincide with the extending direction of the belt cord of the narrow-width inclined belt layer 4c, which is the same as the case on the radially inner side of the tire of the narrow-width inclined belt layer 4c. However, this will increase the manufacturing cost.

[0050] Preferably, the length of the protective layer 8 along the narrow-width inclined belt layer 4c on the radially inner side of the tire of the narrow-width inclined belt layer is 7 mm or more. Figure 5 It is a graph showing the relationship between the length of the protective layer along the narrow-width inclined belt layer (on the radially inner side of the tire) and the crack length. From the test results, it can be seen that when the tire size is 275 / 80R22.5, the rim size is 22.5×7.5J, the internal pressure is 900 kPa, the load is 37.19 kN, and the tire mileage is 100,000 km, when the length along the narrow-width inclined belt layer is 7 mm or more, the protective layer is effective.

[0051] The diameter of the organic fiber cord is preferably between 0.04 mm and 0.60 mm. From Figure 3 it can be known that the rigidity corresponding to the point where "the larger of the strain near the end of the cord of the reinforcing layer and the strain near the end of the organic fiber cord in the protective layer" is smaller can be set as the optimal rigidity value of the organic fiber cord, and the range around this point can be set as the appropriate rigidity range. If the diameter of the organic fiber cord in the protective layer 8 is less than 0.04 mm, the strain near the end of the belt cord to be protected will increase. On the other hand, if the diameter of the organic fiber cord in the protective layer 8 is greater than 0.60 mm, near the end of the organic fiber cord in the protective layer 8 and Figure 2The strain near the turning-back portion as shown in the example in will increase. Therefore, by making the diameter of the organic fiber cord of the protective layer 8 between 0.04 mm and 0.60 mm, the strain near the end of the belt cord and the Figure 2 the strain near the turning-back portion as shown in the example in can be evenly suppressed, thereby suppressing the occurrence and progression of cracks.

[0052] The force when the organic fiber cord elongates by 5% is preferably 2 N to 10 N. Figure 8 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 the turning-back portion of the organic fiber cord. As Figure 8 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 applies 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 7 the fiber 1 in ) or 10 N ( Figure 7 the fiber 2 in ), the crack length decreases. By setting the force when the organic fiber cord elongates by 5% to 10 N or less, the strain near the end of the organic fiber cord of the protective layer 8 and Figure 2 the strain near the turning-back portion as shown in the example in can be effectively reduced. On the other hand, by setting the force when the organic fiber cord elongates by 5% to 2 N or more, the strain near the end of the reinforcing layer can be effectively reduced. In Figure 8 when the force when the organic fiber cord elongates by 5% is 2 N, it is confirmed that the crack is suppressed by about 10%.

[0053] In addition, it is preferable that the number of organic fiber cords per unit width is greater than the number of belt 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 belt cords per unit width, the strain near the end of the belt layer 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.

[0054] Figure 6 is a schematic diagram illustrating the shear deformation caused by the relative position of the belt cord and the organic fiber cord. As Figure 6 schematically shown, the greater the distance between the belt cord and the organic fiber cord, the greater the shear deformation (schematically shown by two parallelograms of different sizes).

[0055] Therefore, under the above-mentioned reference conditions, the distance between the belt cord and the organic fiber cord is preferably from 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.

[0056] 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 can be arranged by being sandwiched between a plurality of same-type or different-type members constituting 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 can be arranged by being sandwiched between the bead filler and other components adjacent to the bead filler. The RF tag can be embedded in any component constituting the tire. Compared with arranging the RF tag by sandwiching between a plurality of components constituting 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 can 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.

[0057] For example, the RF tag can be arranged on the tread surface of the tire. In this way, the RF tag will not be damaged due to the side cut of the tire. For example, the RF tag can be arranged at the center in the tire width direction of the tread surface. The center of the tread is a position where the flexure does not concentrate in the tread surface. 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 both outer sides in the tire width direction. In this example, the RF tag can 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 can 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 can be arranged, for example, at the tread end on the side closer to the reader. In this example, the RF tag can 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.

[0058] For example, the RF tag can be arranged at a position closer to the tire cavity than the carcass, and the carcass includes one or more carcass plies that cross 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 the 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 layer that forms 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. By having a structure in which the RF tag is 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 a structure in which the RF tag is embedded 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 is a position where the multiple carcass plies overlap each other, the RF tag can be arranged between the overlapping carcass plies.

[0059] For example, the RF tag may be disposed in the tread face of the tire radially outside of the belt including one or more belt plies. As an example, the RF tag may be disposed radially outside of the belt and in close contact therewith. As another example, when a reinforcing belt layer is provided, the RF tag may be disposed radially outside of the reinforcing belt layer and in close contact therewith. As yet another example, the RF tag may be embedded in the tread rubber radially outside of the belt. By disposing the RF tag in the tread face of the tire radially outside of the belt, communication with the RF tag from the radially outside 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 outside of the tire. Further, the RF tag may be embedded in the tread rubber radially inside of the belt. In this way, the radially outside of the RF tag is covered by the belt, so that the RF tag is less likely to be damaged by an impact on the tread surface or nail penetration. As this example, the RF tag may be disposed between the belt and the carcass located radially inside of the belt. Further, when the belt includes a plurality of belt plies, the RF tag may be disposed between any two belt plies in the tread face of the tire. In this way, the radially outside of the RF tag is covered by one or more belt plies, so that the RF tag is less likely to be damaged by an impact on the tread surface or nail penetration.

[0060] For truck and bus tires, the RF tag may be disposed, 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 mitigate the impact on the RF tag. This improves the durability of the RF tag. Further, for example, the RF tag may be embedded in the buffer rubber. Further, the buffer rubber may be composed of a plurality of rubber members of the same or different types adjacent to each other. In this case, the RF tag may be disposed by being sandwiched between the plurality of rubber members constituting the buffer rubber.

[0061] The RF tag can be arranged at a position, for example, in the sidewall portion or the bead portion of a tire. For example, the RF tag can be arranged on the sidewall portion or the bead portion on a side close to a 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 a 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 members 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 members constituting the sidewall rubber.

[0062] 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 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 configured 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 configured 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.

[0063] 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 can be located 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 on the outside in 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 reduced by the crown rubber, thereby improving the durability of the RF tag.

[0064] 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 the impact or damage of the rim can be reduced. This improves the durability of the RF tag.

[0065] 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.

[0066] 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 can 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 can be the carcass.

[0067] For passenger car tires, a belt reinforcing layer can be provided on the outer side in the tire radial direction of the belt. For example, the belt reinforcing layer can be formed by cords made of polyethylene terephthalate continuously spirally wound along the tire circumferential direction. The cords are 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. Further, 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 degrading high-speed durability.

[0068] Examples

[0069] 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 was provided with a belt and a protective layer. The belt was composed of at least one belt ply formed of belt cords coated with rubber, and the protective layer was formed of a rubber coating of organic fiber cords and covered the ends of the belt cords. The specifications and evaluation results of the tires are provided in Table 1 below. The indoor durability test was conducted using tires with a size of 275 / 80R22.5, under a load of 37.19 kN, a running distance of 100,000 km, an internal pressure of 900 kPa, and a rim size of 22.5×7.5J. As a comparative example, test tires were manufactured, which were provided with a protective layer formed of organic fibers that applied 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 ends of the reinforcing layer and the higher the durability of the tire.

[0070] [Table 1]

[0071]

[0072] As can be seen from Table 1, it is obvious that the tire durability of the example tires has been improved compared to the comparative example. In addition, when the protective layer has a folded-back portion, no cracks appear near the ends and the folded-back portion of the protective layer.

[0073] [Contributing to the United Nations-led Sustainable Development Goals (SDGs)]

[0074] 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".

[0075] List of Reference Numerals

[0076] 1 Tire

[0077] 2 Bead portion

[0078] 3 Carcass

[0079] 4 Belt

[0080] 5 Tread

[0081] 6 Steel Bead Flipper

[0082] 7 Sidewall

[0083] 8 Protective Layer

[0084] 100 Communication Device

[0085] CL Tire Equatorial Plane

Claims

1. A pneumatic tire, comprising a belt composed of two or more inclined belt layers formed by rubber-coated belt cords that cross each other between layers, wherein a protective layer formed by a rubber coating of organic fiber cords is arranged to cover the ends of the narrow-width inclined belt layer with a shorter width in the tire width direction among two adjacent inclined belt layers, the protective layer turns back at the ends of the narrow-width inclined belt layer, such that the protective layer extends on the radially outer side and the radially inner side of the narrow-width inclined belt layer of the tire, the organic fiber cords have the smallest diameter among all the cords of the components constituting the pneumatic tire, and with respect to the length of the protective layer along the narrow-width inclined belt layer in a cross-sectional view in the tire width direction, the length on the radially inner side of the narrow-width inclined belt layer of the tire is longer than the length on the radially outer side of the narrow-width inclined belt layer of the tire.

2. The pneumatic tire according to claim 1, wherein the length on the radially inner side of the narrow-width inclined belt layer of the tire is 7 mm or more.

3. The pneumatic tire according to claim 1 or 2, wherein the force when the organic fiber cords are elongated by 5% is 2 N to 10 N.

4. The pneumatic tire according to any one of claims 1 to 3, wherein the number of the organic fiber cords per unit width is greater than the number of the belt cords per unit width, and the spacing between adjacent organic fiber cords is 0.1 mm or more.

5. The pneumatic tire according to any one of claims 1 to 4, wherein under the reference conditions that the pneumatic tire is mounted on an applicable rim, filled with a specified internal pressure and unloaded, the distance between the belt cords and the organic fiber cords is 0.2 mm to 1.0 mm.

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