Pneumatic tire

Abstract

This pneumatic tire comprises: a reinforcement layer comprising at least one ply obtained by coating cords with rubber; and a protective layer covering an end portion of the carcass layer and including a rubber-coated organic fiber cord layer. The organic fiber cord has a strength of 2N to 10 N at 5% elongation.

Description

Technical Field

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

[0002] A pneumatic tire has reinforcing members (such as belts, carcasses, chafer plies, etc.) composed of rubber-coated cords. Since the rigidity of the tire rubber and the cords is different, 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 stress concentration at the ends of the belts, carcasses, chafer plies, etc., some methods have been proposed to cover the ends of the cords of the reinforcing members 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 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 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 reinforcing layer composed of at least one ply formed of rubber-coated cords, wherein

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

[0014] the force when the organic fiber cords are stretched by 5% is 2 N to 10 N.

[0015] As used herein, the "force at 5% elongation of the organic fiber cord" 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 the layer, and then the one organic fiber cord is elongated by 5% (in accordance with JIS L 1095:2010).

[0016] Here, the "distance" shall mean the shortest distance between the cord of the reinforcing layer and the organic fiber cord when measured in a direction perpendicular to the extending direction of the cord of the reinforcing layer in a cross-section in the tire width direction.

[0017] As used herein, the term "applicable rim" means a standard rim of applicable dimensions (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 Japan Automobile Tire Manufacturers Association in Japan, the Standard Manual of the European Tyre and Rim Technical Organization in Europe, and the Yearbook of the 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 industrial standards. An example of the "future dimensions to be listed" is the dimensions listed as "future development" in the 2013 edition of the ETRTO). For dimensions 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 dimensions and ply rating, as described in the above JATMA Yearbook and other industrial standards. In the case where the dimensions are 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.

[0018] Effects of the Invention

[0019] According to the present disclosure, a pneumatic tire having improved durability can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a cross-sectional view in the tire width direction of a pneumatic tire according to an embodiment of the present disclosure.

[0021] Figure 2 is Figure 1 an enlarged view of the vicinity of the bead portion in

[0022] Figure 3 is a view showing a first modification of the present embodiment.

[0023] Figure 4 is a view showing a second modification of the present embodiment.

[0024] Figure 5 It is a schematic view and an enlarged view of a region near an end of a carcass ply.

[0025] Figure 6 It is a graph showing the relationship between the rigidity and strain of a protective layer.

[0026] Figure 7 It is a schematic view illustrating shear deformation caused by the relative positions of cords and organic fiber cords in a reinforcing layer.

[0027] Figure 8 It shows a deformation example when the reinforcing layer is a belt.

[0028] Figure 9 It shows a deformation example when the reinforcing layer is a steel bead filler.

[0029] Figure 10 It is a graph showing the physical properties of two types of organic fiber cords.

[0030] Figure 11 It is a graph showing the relationship between the force when an organic fiber cord is stretched by 5% and the crack length near an end or a folded-back portion of the organic fiber cord.

[0031] Figure 12 It is a graph showing the relationship between the overlapping width of cords and organic fiber cords in a reinforcing layer and the crack length near an end of the reinforcing layer.

[0032] Figure 13 It is a hypothetical plan view of a narrow inclined belt layer and a protective layer seen from the radially outer side of a tire.

[0033] Figure 14 It is a graph showing the relationship between the length along a narrow inclined belt layer of a protective layer and the crack length. Detailed Description of the Embodiments

[0034] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0035] Figure 1 It is a cross-sectional view in the tire width direction of a pneumatic tire (hereinafter simply referred to as a tire) according to an embodiment of the present disclosure. Figure 1 Only one half in the tire width direction of the tire bounded by the tire equatorial plane CL is shown, but the other half has the same structure.

[0036] Figure 1 It shows an example of a heavy-duty tire (for trucks and buses), but the present disclosure can also be applied to tires for various other uses, such as passenger car tires, aircraft tires, and mining tires.

[0037] The internal structure of the tire is not particularly limited. However, 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.

[0038] 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 in the tire. 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).

[0039] 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 at a position in the tire width direction.

[0040] 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 disposed 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.

[0041] 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°.

[0042] 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.

[0043] Figure 2 is Figure 1 an enlarged view near the bead portion in Figure 1 andFigure 2 As shown, the tire 1 is provided with a protective layer 8 formed by a rubber coating of organic fiber cords that covers the end portion 3c of the carcass ply. Figure 5 FIG. is a schematic view and an enlarged view of a region near the end portion 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 in the tire width direction of the ply at the carcass turn-back portion 3b, turns back near the end portion 3c of the carcass ply, and extends from the outer side in the tire radial direction to the inner side in the tire width direction of the ply at the carcass turn-back portion 3b, thereby covering the end portion 3c of the carcass ply and its vicinity. The organic fiber cords may be arranged in the form of a "sudare" pattern, with the warp and weft crossing at approximately 90° within the tire. However, the structure of the organic fiber cords is not limited to the "sudare" pattern.

[0044] Figure 3 FIG. is a view showing a first modification of the present embodiment. In this example, the protective layer 8 is disposed 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 portion 3c of the carcass ply.

[0045] Figure 4 FIG. is a view showing a second modification of the present embodiment. In this example, the protective layer 8 is disposed on both the inner and outer sides 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 portion 3c of the carcass ply.

[0046] As shown here, the protective layer 8 may extend from the inner side in the tire radial direction of the end portion 3c of the carcass ply to the tire radial position of the end portion 3c of the carcass ply, or to the outer side in the tire radial direction of the end portion 3c of the carcass ply, on the outer and inner sides in the tire width direction with respect to the carcass turn-back portion 3b. In this way, the end portion 3c of the carcass ply can be covered in various ways.

[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] The force when the organic fiber cords are stretched by 5% is 2 N to 10 N.

[0049] The effects of the pneumatic tire of the present embodiment will be described below.

[0050] The pneumatic tire 1 of the present embodiment includes a carcass 3, which is composed of at least one carcass ply formed by rubber-coated carcass cords, and is provided with a protective layer 8 formed by a rubber coating of organic fiber cords to cover the end 3c of the carcass ply. This protects the end 3c of the carcass ply by means of the protective layer 8 and prevents failures from occurring near the end of the carcass ply. In addition, in the pneumatic tire 1 of the present embodiment, the force when the organic fiber cord elongates by 5% is 2 N to 10 N. Figure 11 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 portion of the organic fiber cord. As Figure 11 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 organic fibers that exert a force of 41 N when elongated) is set to 1, it can be seen that when using organic fiber cords with a force of 4 N when elongated by 5% ( Figure 10 fiber 1 in Figure 10 ) or 10 N ( Figure 2 fiber 2 in Figure 11 ), the crack length decreases. If the force when the organic fiber cord elongates by 5% exceeds 10 N, the strain near the end of the organic fiber cord in the protective layer 8 or

[0051] near the folded-back portion in the example of Figure 3 and Figure 4 cannot be effectively reduced. On the other hand, if the force when the organic fiber cord elongates by 5% is less than 2 N, the strain near the end of the reinforcing layer cannot be effectively reduced. In Figure 2 and Figure 4 , when the force when the organic fiber cord elongates by 5% is 2 N, about 10% of crack suppression is confirmed. Figure 5 As described above, the pneumatic tire of the present embodiment can improve the durability of the tire. The same effect can also be obtained for the modified examples shown in

[0052] Figure 8 . In particular, in the case of the examples shown in

[0053] Figure 2 and Figure 4 , the effect of suppressing the strain near the ends of the reinforcing layers on the inner and outer sides in the tire width direction of the reinforcing layer can be obtained, while in the case of the example shown in Figure 5 , it is advantageous in terms of reducing the number of components.

[0052] Figure 8 shows a modified example when the reinforcing layer is a belt. In the example shown in the figure, the protective layer 8 formed by a rubber coating of organic fiber cords covers the end of the narrow inclined belt layer 4c with a shorter width in the tire width direction among two adjacent inclined belt layers (4b, 4c).

[0053] Also in this case, for the same reasons as described above, by setting the strain to be 2N to 10N when the organic fiber cord elongates by 5%, the strain near the end of the belt layer 4c and the strain near the end and the folded-back portion of the organic fiber cord can be suppressed, and the durability of the tire can be improved.

[0054] In addition, a protective layer 8 can also be arranged to cover the ends of the inclined belt layers 4a, 4b or 4d.

[0055] Figure 9 A deformation example when the reinforcing layer is a steel bead filler is shown. In the example shown in the figure, the protective layer 8 formed by the rubber coating of the organic fiber cord covers the end (on the outer side in the tire width direction of the bead filler 2b) of the steel bead filler 6.

[0056] Also in this case, for the same reasons as described above, by setting the strain to be 2N to 10N when the organic fiber cord elongates by 5%, the strain at and near the end of the steel bead filler 6 and the strain near the end and the folded-back portion of the organic fiber cord can be suppressed, and the durability of the tire can be improved.

[0057] It should be noted that even in Figure 8 and Figure 9 cases, the protective layer 8 can also be configured to extend on the outer side and / or the inner side in the tire radial direction of the belt layer (as a structure without a folded-back portion), as exemplified in Figure 3 and Figure 4 in the case of the carcass, or can be configured to extend on the outer side and / or the inner side in the tire width direction of the steel bead filler 6.

[0058] Here, preferably, the organic fiber cord has the smallest diameter among all the cords of the components constituting the pneumatic tire. For example, 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 predictive calculations). As Figure 6 shown, the higher the rigidity of the protective layer 8, the smaller the strain near the carcass cord ends of the reinforcing layer (the carcass in the present embodiment) 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 the strain near the ends of the organic fiber cords in the protective layer 8 and Figure 2In the example of [], a large strain is generated near the folded-back 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 can lead to tire failure. Therefore, the optimal rigidity value of the organic fiber cord can be determined as the rigidity corresponding to the point where the strain in the area near the end of the cord in the reinforcing layer is smaller than the larger of the strains in the area near the end of the organic fiber cord in the protective layer, and the range around this point can be set as an appropriate rigidity range. Here, among all the cords of the components constituting 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 near the folded-back portion in the example of [].

[0059] In particular, by setting the diameter of the organic fiber cord in the protective layer 8 to 0.04 mm or more, it is possible to reduce the strain near the end of the carcass cord to be protected. On the other hand, by setting the diameter of the organic fiber cord in the protective layer 8 to 0.60 mm or less, it is possible to reduce the strain near the end of the organic fiber cord in the protective layer 8 and Figure 2 near the folded-back portion in the example of []. Therefore, by making the diameter of the organic fiber cord of the protective layer 8 between 0.04 mm 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 near the folded-back portion in the example of [] in a balanced manner, and it is possible to more reliably suppress the occurrence and progression of cracks.

[0060] In addition, it is preferable that the number of organic fiber cords per unit width is greater than the number of cords in the reinforcing layer 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 cords in the reinforcing layer per unit width, it is possible to further reduce the strain near the end of the reinforcing layer. 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 showing the shear deformation caused by the relative positions of the cords in the reinforcing layer and the organic fiber cords. As Figure 7 schematically shown, the greater the distance between the cords of the reinforcing layer and the organic fiber cords, 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 cords of the reinforcing layer and the organic fiber cords 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 the manufacturing perspective, the above distance is preferably 0.2 mm or more. It should be noted that when the above 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 applies a force of 41 N when stretched.

[0063] In addition, as Figure 7 shown, the longer the overlapping width (the overlapping width along the extending direction of the cords of the reinforcing layer) between the cords of the reinforcing layer and the organic fiber cords, the smaller the shear deformation. Therefore, under the above-mentioned reference conditions, the overlapping width between the cords of the reinforcing layer and the organic fiber cords 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 12 is a graph showing the relationship between the overlapping width of the cords in the reinforcing layer and the organic fiber cords and the crack length near the end of the reinforcing layer. As Figure 12 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 when 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 cords, from the manufacturing perspective, preferably, the angle formed between the cords of the reinforcing layer and the organic fiber cords 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 cords 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] When the reinforcing layer is the carcass 3, the organic fiber cords of the protective layer 8 have the smallest diameter among the cords of the components constituting the pneumatic tire, and at least a part of the organic fiber cords preferably extends beyond the end of the carcass ply to the radially outer side of the tire.

[0066] 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 the rolling of the tire. As a result, there is a concern that sufficient tire life will not be obtained. On the other hand, in the area closer to the radially outer side of the tire, the bending deformation of the contact area of ​​the bead portion 2 during the rolling of the tire 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.

[0067] 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.

[0068] Here, the minimum distance between the end of the organic fiber cord or the vertex position of the folded portion of the organic fiber cord and the end of the carcass ply is preferably 5 mm to 37 mm. By making the minimum distance 5 mm or more and 37 mm or less, the end 3c of the carcass ply can be brought 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 moved away from the rim flange portion, thereby effectively obtaining the above-mentioned effect.

[0069] When the reinforcing layer is a belt layer, it is preferred to arrange a protective layer 8 formed by a rubber coating of an organic fiber cord to cover the ends of a narrow width inclined belt layer having a shorter width in the tire width direction in two adjacent inclined belt layers; the protective layer 8 is folded back at the ends of the narrow width inclined belt layer so that the protective layer extends to the tire radial outside and inside of the narrow inclined belt layer; the organic fiber cord has the smallest diameter among all the cords constituting the components of the pneumatic tire; and, with respect to the length of the protective layer 8 along the narrow inclined belt layer in a cross-sectional view in the tire width direction, the length on the tire radial inside of the narrow inclined belt layer (along the narrow inclined belt layer) is longer than the length on the tire radial outside of the narrow inclined belt layer (along the narrow inclined belt layer).

[0070] Near the end of the narrow inclined belt layer 4c having a shorter width in the tire width direction in adjacent inclined belt layers, strain that causes fracture cracks occurs on the tire radial inner side of the end of the narrow inclined belt layer 4c. Therefore, by making the length (along the narrow inclined belt layer 4c) on the tire radial inner side relatively long, the occurrence and development of cracks can be effectively suppressed. Figure 13 It is a hypothetical plan view of the narrow 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 inclined belt layer 4c is large, the extending direction of the organic fiber cord of the protective layer 8 is preferably along the extending direction of the belt cord of the narrow inclined belt layer 4c. On the other hand, when such an organic fiber cord turns back at the end of the narrow inclined belt layer 4c, as Figure 13 schematically shown, the organic fiber cord and the belt cord cross each other. During the tire manufacturing process, when assembling various components with the protective layer already in place on the narrow inclined belt layer 4c, a tool such as a cutter is used to cut the narrow 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 13 an example of the cutting surface is shown by the symbol A in ). Therefore, by making the length of the protective layer (along the narrow inclined belt layer) on the tire radial outer side of the narrow 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 inclined belt layer 4c in the tire width direction cross-section, the length on the tire radial inner side of the narrow inclined belt layer 4c is greater than the length on the tire radial outer side of the narrow 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 tire radial outer side, the extending direction of the organic fiber cord in the protective layer 8 can be made to be the same as the extending direction of the belt cord in the narrow inclined belt layer 4c, which is the same as the case on the tire radial inner side. However, this will increase the manufacturing cost.

[0071] Preferably, the length of the protective layer 8 (along the narrow inclined belt layer 4c) on the tire radial inner side of the narrow inclined belt layer is 7 mm or more. Figure 14 It is a graph showing the relationship between the length of the protective layer along the narrow inclined belt layer (on the tire radial inner side) and the crack length. It can be seen from the test results 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 travels 100,000 km, the protective layer is effective when the length along the narrow inclined belt layer is 7 mm or more.

[0072] It should be noted that the "length of the protective layer along the narrow 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 inclined belt layer in the cross-sectional view in the tire width direction. Here, the above-mentioned "width" or "length" in the tire width direction should refer to the size of the inflated tire when the tire is mounted on the applicable rim, filled with the specified internal pressure and without load. 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 circumferential direction of the tire between two inclined belt layers, these two inclined belt layers are regarded as adjacent to each other.

[0073] 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 multiple same-type or different-type components that make up 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 that makes up the tire. Compared with arranging the RF tag by sandwiching between multiple components that make up 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 the 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 in the cross-sectional view in the tire width direction and the component adjacent to the carcass end (such as sidewall rubber). 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 can also be used.

[0074] 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, for example, within 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 for communicating 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, for example, within a range of 1 / 4 of the tread width in the tire width direction with the tread end as the outer end.

[0075] 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 the other 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, the RF tag can be easily attached to the tire, and the RF tag can be inspected and replaced. 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 a plurality of carcass plies and there is a position where the plurality of carcass plies overlap each other, the RF tag can be arranged between the overlapping carcass plies.

[0076] For example, the RF tag may be disposed in the tread portion 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 reinforced belt layer is provided, the RF tag may be disposed radially outside of the reinforced 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 portion 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. Thus, the radially outside of the RF tag is covered by the belt, and thus the RF tag is less likely to be damaged by an impact on the tread surface or a nail insertion. 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 portion of the tire. Thus, the radially outside of the RF tag is covered by one or more belt plies, and thus the RF tag is less likely to be damaged by an impact on the tread surface or a nail insertion.

[0077] 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. Thus, 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.

[0078] 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 capable of communicating 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 with 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.

[0079] 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 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.

[0080] For truck and bus tires, the RF tag can be arranged between the reinforcing member and the member adjacent to the reinforcing member. In this way, the RF tag can be arranged at a position where strain concentration is less likely to occur due to the placement of the reinforcing member. 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 reinforcing member and the sidewall rubber. Alternatively, the RF tag can also be arranged by being sandwiched between the reinforcing member and the carcass. The portion of the carcass that holds the RF tag and the reinforcing member in place can be located outside the tire width direction with respect to the reinforcing member or inside the tire width direction with respect to the reinforcing member. When the portion of the carcass that holds the RF tag and the reinforcing member in place is located outside the tire width direction with respect to the reinforcing member, the load applied to the RF tag due to 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 reinforcing member can also include a portion disposed adjacent to the rubber bead filler. In this case, the RF tag can be arranged by being sandwiched between the reinforcing member and the rubber bead filler. The reinforcing member 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 arranged by being sandwiched between the reinforcing member and the crown rubber. The reinforcing member can be composed of a plurality of rubber members with different hardnesses. In this case, the RF tag can be arranged by being sandwiched between the plurality of rubber members that make up the reinforcing member. The RF tag can be arranged by being sandwiched between the crown rubber and the member adjacent to the crown rubber. For example, the RF tag can be arranged 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.

[0081] The RF tag can be arranged, for example, between the rubber bead filler and the sidewall rubber. In this way, the RF tag can be arranged at a position where strain concentration is less likely to occur due to the arrangement of the rubber bead filler. This reduces the load applied to the RF tag and improves the durability of the RF tag. The RF tag can be arranged, for example, by being sandwiched between the rubber bead filler and the carcass. In this way, the load applied to the RF tag due to impact or damage to the rim can be reduced. This improves the durability of the RF tag.

[0082] 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 in the tire width direction of the RF tag is covered with the nylon chafer, the load applied to the RF tag due to impact or damage on the outer side in the tire width direction of the tire can be further reduced. This makes it possible to further improve the durability of the RF tag.

[0083] 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.

[0084] 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 by cords made of polyethylene terephthalate continuously wound in a spiral along the tire circumference. The cords are passed 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 may be arranged to cover the entire belt or may be arranged to cover only both ends of the belt. Further, the winding density per unit width of the belt reinforcing layer may 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.

[0085] Examples

[0086] 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 reinforcing layer and a protective layer. The reinforcing layer was composed of at least one ply formed of rubber-coated cords, and the protective layer was formed of a rubber coating of organic fiber cords and covered the ends of the ply of the reinforcing layer. The specifications and evaluation results of each tire are provided in Table 1 below. The indoor durability test was conducted as follows: When the reinforcing layer was a belt layer, a tire with a size of 275 / 80R22.5, a load of 37.19 kN, and a driving distance of 100,000 km was used; when the reinforcing layer was a carcass ply, a tire with a size of 275 / 80R22.5, a load of 43.95 kN, and a driving distance of 50,000 km was used; when the reinforcing layer was a steel bead filler, a tire with a size of 445 / 50R22.5, a load of 43.95 kN, and a driving distance of 50,000 km was used. Regardless of the type of the reinforcing layer, the internal pressure was 900 kPa and the rim was 22.5×7.5J. As a comparative example, a test tire was manufactured, which was provided with a protective layer formed of an organic fiber that applied a force of 41 N when stretched. The evaluation results were 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.

[0087] [Table 1]

[0088]

[0089] As can be seen from Table 1, it is obvious that the tire durability of Examples 1 to 5 is improved compared to the comparative example. In addition, when the protective layer has a folded-back portion, cracks do not appear near the ends of the protective layer and its folded-back portion.

[0090] [Contributing to the United Nations-led Sustainable Development Goals (SDGs)]

[0091] 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".

[0092] List of Reference Numerals

[0093] 1 Tire

[0094] 2 Bead

[0095] 3 Carcass

[0096] 4 Belt

[0097] 5 Tread

[0098] 6 Steel Bead Flipper

[0099] 7 Sidewall

[0100] 8 Protective Layer

[0101] 100 Communication Device

[0102] CL Tire Equatorial Plane

Claims

1. An inflatable tire comprising a reinforcing layer composed of at least one ply formed of rubber-coated cords, wherein a protective layer formed of a rubber coating of organic fiber cords is disposed to cover an end portion of the ply, and a force when the organic fiber cords are stretched by 5% is 2 N to 10 N.

2. The pneumatic tire according to claim 1, wherein, The organic fiber cords have the smallest diameter among the cords of the components constituting the inflatable tire.

3. The inflatable tire according to claim 1 or 2, wherein a number of the organic fiber cords per unit width is larger than a number of the cords of the reinforcing layer per unit width, and a spacing between the adjacent organic fiber cords is 0.1 mm or more.

4. The inflatable tire according to any one of claims 1 to 3, wherein, under reference conditions where the inflatable tire is mounted on a suitable rim, filled with a prescribed internal pressure, and unloaded, a distance between the cords of the reinforcing layer and the organic fiber cords is 0.2 mm to 1.0 mm.

5. The inflatable tire according to any one of claims 1 to 4, wherein, under reference conditions where the inflatable tire is mounted on a suitable rim, filled with a prescribed internal pressure, and unloaded, an overlapping width between the cords of the reinforcing layer and the organic fiber cords is 10 mm or more.

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