pneumatic tires

Abstract

The present invention provides a pneumatic tire in which the sidewall markings are formed by recesses, thereby suppressing the reduction in durability and handling stability of the pneumatic tire. [Solution] The pneumatic tire 100 is a pneumatic tire 100 in which the markings on the sidewall 12 are formed by recesses 80, and a reinforcing layer 90 is provided between the carcass plies 15A that make up the carcass 15, or between the carcass plies 15A and the inner liner 16, and the reinforcing layer 90 is arranged so as to overlap at least with the recesses 80 in the tire radial direction when viewed from the tire axial direction.

Description

Technical Field

[0001] The present invention relates to pneumatic tires.

Background Art

[0002] Pneumatic tires (hereinafter simply referred to as tires) may be used for BEVs (Battery Electric Vehicles). A BEV runs by driving a motor. A BEV also mounts a battery that supplies power to the motor. The battery is a heavy object. Therefore, the load on the tires used for electric vehicles increases as compared with the load on the tires used for engine vehicles.

[0003] Therefore, the European Tyre and Rim Technical Organisation (ETRTO), which is a European tire association, has set high load capacity tires (hereinafter referred to as HL tires) that can withstand a larger load than existing XL tires. HL tires are tires designed to support heavier vehicles such as BEVs, HEVs (Hybrid Electric Vehicles), and SUVs (Sport Utility Vehicles). In HL tires, for example, even when filled with the same air pressure at the same size as XL tires, they can support a larger weight (for example, Patent Document 1).

[0004] In the above-described HL tires, the most distortion occurs near the maximum width of the sidewall portion. By the way, on the sidewall portion of the tire, the brand name, size, model number, etc. of the tire are indicated. In recent years, in consideration of the designability of the tire, the indication on the sidewall portion may be formed by a recess. When the indication on the sidewall portion is formed by a recess, the rubber thickness of the portion where the distortion is concentrated becomes thin, and there is a risk that the durability and handling stability will decrease.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-068958 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] As mentioned above, if the markings on the sidewall of an HL tire are formed by a recess, the rubber thickness in the area where the strain is concentrated may be reduced, potentially decreasing durability and handling stability.

[0007] Therefore, the present invention aims to provide a pneumatic tire that can suppress the reduction in durability and handling stability of a pneumatic tire in which the markings on the sidewall are formed by recesses. [Means for solving the problem]

[0008] The pneumatic tire according to the present invention is a pneumatic tire in which the markings on the sidewall are formed by recesses, and a reinforcing layer is provided between the carcass plies constituting the carcass, or between the carcass plies and the inner liner, and the reinforcing layer is arranged so as to overlap at least with the recesses in the tire radial direction when viewed from the tire axial direction. [Effects of the Invention]

[0009] According to the pneumatic tire of the present invention, the reduction in durability and handling stability of the pneumatic tire can be suppressed by the formation of recesses in the sidewall markings. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view showing a pneumatic tire according to an embodiment. [Figure 2] This is a detailed view of section A in Figure 1. [Modes for carrying out the invention]

[0011] An example of an embodiment of the present invention will be described in detail below. In the following description, specific shapes, materials, directions, numerical values, etc., are examples to facilitate understanding of the present invention and can be appropriately modified according to the application, purpose, specifications, etc.

[0012] An embodiment of the pneumatic tire 100 will be described using Figure 1.

[0013] The pneumatic tire 100 comprises a tread 10 which is the part that contacts the road surface, a pair of sidewalls 12 located on both sides of the tread 10, a pair of beads 14 located radially inward of the sidewalls 12, a carcass 15 spanning between the pair of beads 14, and an inner liner 16 located radially inward of the carcass 15.

[0014] The tread 10 is made of tread rubber 11. In this embodiment, the tread 10 has a main groove 30 (center main groove) formed on the tire equator CL, and a pair of main grooves 31 and 32 (shoulder main grooves). The three main grooves 30, 31 and 32 are formed straight along the tire circumferential direction without curving in the tire axial direction.

[0015] The tread 10 has a center block 40 (first center block) demarcated by main grooves 30 and 31, and a center block 50 (second center block) demarcated by main grooves 30 and 32. The tread 10 also has a shoulder block 60 (first shoulder block) positioned opposite the first center block 40 in the tire axial direction, straddling the shoulder main groove 31, and a shoulder block 70 (second shoulder block) positioned opposite the second center block 50 in the tire axial direction, straddling the shoulder main groove 32. Each block is formed straight along the tire circumferential direction. A block is a portion that rises outward in the tire radial direction from a position corresponding to the bottom of a main groove, and is also called a land area.

[0016] The sidewall 12 is composed of a different type of sidewall rubber 13 than the tread rubber 11. The sidewall 12 is positioned on both sides of the tread 10 and is formed in an annular shape along the circumferential direction of the tire. The sidewall 12 is the part of the pneumatic tire 100 that protrudes most outward in the tire axial direction and is gently curved so as to be convex outward in the tire axial direction. The sidewall 12 has the function of preventing damage to the carcass 15. The sidewall 12 is the part of the pneumatic tire 100 that flexes the most when it acts as a cushion, and is usually made of a flexible rubber with fatigue resistance.

[0017] The tire brand name, size, model number, etc., are indicated on the sidewall 12. The markings on the sidewall are formed by recesses 80. In the pneumatic tire 100, the part that experiences the greatest distortion when a load is applied is the sidewall 12. In the recesses 80 of the sidewall 12, the rubber thickness is reduced, so when a load is applied to the pneumatic tire 100, the distortion concentrates there. Therefore, the durability and handling stability of the pneumatic tire 100 may decrease. To address this, in the pneumatic tire 100 of this embodiment, the recesses 80 are reinforced by a reinforcing layer 90, which will be described in detail later.

[0018] The bead 14 is the portion of the sidewall 12 located radially inward of the tire and fixed to the rim of the wheel. The bead 14 has a bead core 17 and a bead filler 18. The bead core 17 is made of steel bead wire and is an annular member that extends around the entire circumference in the circumferential direction of the tire and is embedded in the bead 14. The bead filler 18 is an annular hard rubber member that has a tapered shape extending outward radially in the tire and extends around the entire circumference in the circumferential direction of the tire.

[0019] The carcass 15 is stretched between a pair of beads 14 and is locked by being folded around the bead core 17. The carcass 15 is composed of at least one carcass ply 15A (see FIG. 2). A reinforcing layer 90, the details of which will be described later, may be provided between the carcass plies 15A. The carcass ply 15A includes a carcass cord (not shown) made of organic fibers. The carcass cord is arranged substantially perpendicular (e.g., 80° - 90°) to the tire circumferential direction. Examples of the organic fibers used for the carcass cord include polyester fibers, rayon fibers, aramid fibers, and nylon fibers.

[0020] The inner liner 16 covers the inner surface of the tire between the pair of beads 14. The inner liner 16 is made of air-permeability-resistant rubber and has the function of maintaining the air pressure of the pneumatic tire 100. A reinforcing layer 90, the details of which will be described later, is provided between the carcass ply 15A and the inner liner 16 (see FIG. 2).

[0021] The pneumatic tire 100 further includes a belt 19 arranged on the outer side in the tire radial direction of the carcass 15, a cap ply 22 covering the entire outer side in the tire radial direction of the belt 19, and an edge ply 23 arranged on the outer side in the tire radial direction of the cap ply 22 and covering both axial ends of the belt 19 in the tire axial direction. The cap ply 22 and the edge ply 23 have the function of reinforcing the belt 19.

[0022] The belt 19 is arranged on the outer peripheral side of the top of the carcass 15 and is provided overlapping the outer peripheral surface of the carcass 15. The belt 19 is formed of a belt ply in which cords arranged in a direction inclined with respect to the tire circumferential direction are rubber-coated. The material of the cords of the belt 19 is not particularly limited, and examples include organic fibers such as polyester, rayon, nylon, and aramid, or metals such as steel. In the present embodiment, the belt 19 is composed of two belt plies including steel cords. The number of belt plies is not particularly limited and may be one or three or more.

[0023] Between the tread 10 and the belt 19, a cap ply 22 and an edge ply 23 are disposed. In the present embodiment, the cap ply 22 and the edge ply 23 are configured as a single continuous member. The cap ply 22 and the edge ply 23 are obtained by continuously winding an organic fiber cord aligned in the longitudinal direction in a spiral shape with respect to the tire circumferential direction. Examples of the organic fiber used for the cap ply 22 and the edge ply 23 include aramid fiber, polyester fiber, and nylon fiber.

[0024] The end of the cap ply 22 is located outside the end of the belt 19 in the tire axial direction. That is, the cap ply 22 is disposed between the belt 19 and the tread rubber 11 so as to cover the entire outside in the tire radial direction of the belt 19.

[0025] The edge ply 23 is disposed adjacent to the outside in the tire radial direction of the cap ply 22 in the tire radial direction so as to cover both ends of the belt 19. In the present embodiment, both ends in the tire axial direction of the cap ply 22 are folded back, and the folded-back portions are the edge ply 23. The edge ply 23 disposed at both ends of the belt 19 are spaced apart from each other in the tire axial direction.

[0026] [Reinforcement layer] An example of the reinforcement layer 90 in the embodiment will be described using FIG. 2.

[0027] As described above, the reinforcement layer 90 is provided between the carcass plies 15A or between the carcass ply 15A and the inner liner 16. In the example of FIG. 2, the reinforcement layer 90 is provided between the carcass ply 15A and the inner liner 16. The reinforcement layer 90 is disposed so as to at least overlap the recess 80 in the tire radial direction when viewed from the tire axial direction.

[0028] Here, "the reinforcing layer 90 and the recess 80 overlap when viewed from the tire axial direction" means that, in a cross-section along the tire radial direction, the reinforcing layer 90 and the recess 80 overlap when viewed from the direction normal to the center point of the arc-shaped bottom surface 80A of the recess 80.

[0029] In other words, "the reinforcing layer 90 and the recess 80 overlap when viewed from the tire axis direction" means that when the arc-shaped bottom surface 80A of the recess 80 is slid to the arc-shaped reinforcing layer 90 in a cross-section along the tire radial direction, the bottom surface 80A and the reinforcing layer 90 are approximately coincident. Furthermore, "sliding the bottom surface 80A of the arc-shaped recess 80" means sliding the bottom surface 80A of the recess 80 along the normal direction from the center point of the arc of the bottom surface 80A of the recess 80.

[0030] The reinforcing layer 90 can reduce the distortion of the recess 80 in the sidewall 12 by reinforcing it. This can improve the durability and handling stability of the pneumatic tire 100.

[0031] It is preferable that the reinforcing layer 90 is positioned so as to straddle one end (the stepped portion) of the recess 80 in the tire radial direction when viewed from the tire axial direction. Here, "positioned so as to straddle one end (the stepped portion) of the recess 80 in the tire radial direction" means that the outer or inner end (the stepped portion) of the recess 80 in the tire radial direction overlaps with the reinforcing layer 90. This concentrates the edges (the stepped portion) of the recess 80 and the edges (the stepped portion) of the reinforcing layer 90, thereby reducing the occurrence of process defects.

[0032] The reinforcing layer 90 is positioned so as to overlap with 50% or more of the recess 80 in the tire radial direction when viewed from the tire axial direction. Here, "the reinforcing layer 90 overlaps with 50% or more of the recess 80 in the tire radial direction" means that 50% or more of the recess 80 in the tire radial direction must overlap with the reinforcing layer 90. For example, 50% or more of the outer part of the recess 80 in the tire radial direction may overlap with the reinforcing layer 90. Alternatively, 50% or more of the central part of the recess 80 in the tire radial direction may overlap with the reinforcing layer 90. Furthermore, 50% or more of the inner part of the recess 80 in the tire radial direction may overlap with the reinforcing layer 90.

[0033] As a result, in the process of placing the reinforcing layer 90, it is sufficient to visually position the center or one end of the reinforcing layer 90 in the center of the recess 80 in the radial direction of the tire when viewed from the tire axis direction. Consequently, work efficiency can be improved.

[0034] The reinforcing layer 90 is positioned around the entire circumference of the tire in the circumferential direction. In other words, the reinforcing layer 90 is not positioned in a location corresponding to the recess 80 of the sidewall 12 in the circumferential direction of the tire.

[0035] The reinforcing layer 90 is made of rubber with a JIS hardness of 60 to 100, for example. The thickness of the reinforcing layer 90 is preferably 0.3 mm to 1.0 mm.

[0036] The axle-side end of the reinforcing layer 90 is preferably positioned to overlap with the winding end of the carcass 15. The overlapping area between the axle-side end of the reinforcing layer 90 and the winding end of the carcass 15 is preferably 45 mm or less.

[0037] Furthermore, it is preferable that the axle-side end of the reinforcing layer 90 overlaps with the tip of the bead filler 18. The overlapping area between the axle-side end of the reinforcing layer 90 and the tip of the bead filler 18 is preferably 25 mm or less. [Examples]

[0038] The present invention will be further described below with reference to examples, but the present invention is not limited to these examples.

[0039] <Example 1> Reinforcement layer (hardness 50, thickness 0.5 mm, Poisson's ratio 0.49, tensile strength 0.374 kgf / mm²) 2 A pneumatic tire A1 (tire size: 215 / 55R17, rim size: 17×7.0J) was manufactured with a reinforcement layer. The reinforcement layer was positioned so that it overlapped with 50% of the recess in the radial direction of the tire when viewed from the tire axial direction. The reason why the reinforcement layer overlapped with 50% of the recess in the radial direction of the tire when viewed from the tire axial direction was that it was possible to position the center or one end of the reinforcement layer at the center of the recess in the radial direction of the tire when viewed from the tire axial direction was the easiest method of manufacturing, and this was used as the standard.

[0040] <Example 2> A pneumatic tire A2 was manufactured in the same manner as in Example 1, except that the reinforcing layer was positioned so as to overlap 70% of the recess in the tire radial direction when viewed from the tire axial direction.

[0041] <Example 3> A pneumatic tire A3 was manufactured in the same manner as in Example 1, except that the reinforcing layer was positioned so as to overlap 100% of the recess in the radial direction of the tire when viewed from the tire axial direction.

[0042] <Comparative Example 1> A pneumatic tire B1 was manufactured in the same manner as in Example 1, except that the reinforcing layer was positioned so as to overlap (or not overlap) with 0% of the recess in the tire radial direction when viewed from the tire axial direction.

[0043] <Comparative Example 2> A pneumatic tire B2 was manufactured in the same manner as in Example 1, except that the reinforcing layer was positioned so as to overlap 30% of the recess in the tire radial direction when viewed from the tire axial direction.

[0044] [distorted] For pneumatic tires A1-A3 and B1-B2, the strain energy in the area where the recess and the reinforcing layer overlap was evaluated with an air pressure of 230 kPa and a load of 900 kgf, using pneumatic tire A1 from Example 1 as a baseline of 100. The evaluation results are shown in Table 1. In the evaluation, a larger value indicates lower strain energy, and a smaller value indicates higher strain energy.

[0045] [Table 1]

[0046] Compared to Example 1, Examples 2-3, where the overlap with the recess was greater than in Example 1, showed a decrease in strain energy. On the other hand, Comparative Examples 1-2, where the overlap with the recess was less than in Example 1, showed an increase in strain energy compared to Example 1.

[0047] [summary] The present invention is further described by the following embodiments. Configuration 1: A pneumatic tire in which the markings on the sidewall are formed by a recess, A reinforcing layer is provided between the carcass plies that make up the carcass, or between the carcass plies and the inner liner. The reinforcing layer is arranged such that it at least overlaps with the recess in the radial direction of the tire when viewed from the tire axial direction. Pneumatic tires. Configuration 2: The pneumatic tire described in Configuration 1, The reinforcing layer is positioned such that, when viewed from the tire axis, it straddles one end of the recess in the tire radial direction. Pneumatic tires. Configuration 3: The pneumatic tire described in configuration 2, The reinforcing layer is arranged so as to overlap with 50% or more of the recess in the tire radial direction when viewed from the tire axial direction. Pneumatic tires. Configuration 4: The pneumatic tire described in configuration 3, The reinforcing layer has a rubber hardness of JIS hardness 60 to 100 and a thickness of 0.3 mm to 1.0 mm. Pneumatic tires. Configuration 5: The pneumatic tire described in configuration 4, The inner end of the reinforcing layer in the tire radial direction overlaps with the winding end of the carcass. Pneumatic tires. Configuration 6: The pneumatic tire described in configuration 5, The inner end of the reinforcing layer in the tire radial direction overlaps with the tip of the bead filler. Pneumatic tires.

[0048] It should be noted that the present invention is not limited to the embodiments and their modifications described above, and various changes and improvements are possible within the scope of the claims of this application. [Explanation of Symbols]

[0049] 10 Tread, 11 Tread rubber, 12 Sidewall, 13 Sidewall rubber, 14 Bead, 15 Carcass, 15A Carcass ply, 16 Inner liner, 17 Bead core, 18 Bead filler, 19 Belt, 19A End, 20 Belt ply, 20A End, 21 Belt ply, 22 Cap ply, 23 Edge ply, 80 Recess, 80A Bottom, 90 Reinforcement layer, 100 Pneumatic tire

Claims

1. A pneumatic tire in which the markings on the sidewall are formed by a recess, A reinforcing layer is provided between the carcass plies that make up the carcass, or between the carcass plies and the inner liner. The reinforcing layer is arranged such that it at least overlaps with the recess in the radial direction of the tire when viewed from the tire axial direction. Pneumatic tires.

2. A pneumatic tire according to claim 1, The reinforcing layer is positioned such that, when viewed from the tire axis, it straddles one end of the recess in the tire radial direction. Pneumatic tires.

3. A pneumatic tire according to claim 2, The reinforcing layer is arranged so as to overlap 50% or more of the recess in the tire radial direction when viewed from the tire axial direction. Pneumatic tires.

4. A pneumatic tire according to claim 3, The reinforcing layer has a rubber hardness of JIS hardness 60 to 100 and a thickness of 0.3 mm to 1.0 mm. Pneumatic tires.

5. A pneumatic tire according to claim 4, The inner end of the reinforcing layer in the tire radial direction overlaps with the winding end of the carcass. Pneumatic tires.

6. A pneumatic tire according to claim 5, The inner end of the reinforcing layer in the tire radial direction overlaps with the tip of the bead filler. Pneumatic tires.

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