Tire

Abstract

To provide a tire that can be improved in visibility of a pattern part.SOLUTION: The tire comprises, on a tire surface 5A (3A), a pattern part 4 constituted of a continuous ridge 7 arranged based on a curve line having self-similarity. This enables the pattern part 4 to be arranged so that the ridge 7 is suppressed from being roughly arranged to equalize arrangement densities and the ridge 7 is directed toward a plurality of directions, which enables the ridge 7 to disperse and reflect emitted light. This enables the pattern part 4 to be blackened to improve visibility of the pattern part 4.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to a tire, and more particularly to a tire that can improve the visibility of a pattern portion. [Background technology]

[0002] Some conventional tires have a pattern made up of multiple protrusions on the surface of the tire side to improve the visibility of the pattern. For example, a tire described in Patent Document 1 has a decorative strip formed from protrusions on the sidewall, which has a decorative element formed by repeating repeating elements, and the decorative element extends continuously without interruption, and the repeating element is made up of multiple straight line portions and multiple connecting portions connecting the straight line portions, and the multiple straight line portions have two to six different directions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-013619 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to improve the visibility of the marking, it is conceivable to provide a pattern that makes the marking stand out. Even in such a case, it is desirable to further improve the visibility of the pattern.

[0005] The present invention has been made in view of the above, and has an object to provide a tire that can improve the visibility of a pattern portion. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, a tire according to one aspect of the present invention is provided with a pattern portion on the tire surface consisting of continuous ridges arranged based on self-similar curves. [Effects of the Invention]

[0007] The tire according to the present invention has an effect of improving the visibility of the pattern portion. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view of a pneumatic tire according to an embodiment taken along the tire meridian direction. [Figure 2] FIG. 2 is a plan view showing a tire side portion of the tire shown in FIG. [Figure 3] FIG. 3 is an enlarged view of a part of the marking portion on the tire side shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view of a portion of the marking portion shown in FIG. [Figure 5] FIG. 5 is an enlarged view of a part of the marking portion on the tire side portion shown in FIG. [Figure 6] FIG. 6 is a cross-sectional view of a portion of the marking portion shown in FIG. [Figure 7] FIG. 7 is an enlarged view of a part of the marking portion on the tire side portion shown in FIG. [Figure 8] FIG. 8 is a cross-sectional view of a portion of the marking portion shown in FIG. [Figure 9] FIG. 9 is a plan view of the pattern portion. [Figure 10] FIG. 10 is a detailed view of part D in FIG. [Figure 11] FIG. 11 is a partially enlarged cross-sectional view of the pattern portion. [Figure 12] FIG. 12 is an explanatory diagram of the Sierpinski curve. [Figure 13] FIG. 13 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory diagram showing a pattern portion different from that of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to these embodiments. Furthermore, the components of these embodiments include those that can be substituted and are obvious substitutes while maintaining the identity of the invention. Furthermore, the multiple modifications described in these embodiments can be arbitrarily combined within the scope obvious to those skilled in the art.

[0010] [Embodiment] Fig. 1 is a cross-sectional view in the tire meridian direction of a pneumatic tire 1 according to an embodiment. Fig. 1 shows a cross-sectional view of one side region in the tire radial direction of the pneumatic tire 1 mounted on a rim 20. In the embodiment, a pneumatic tire, that is, a pneumatic radial tire for passenger cars, will be described as an example of a tire.

[0011] The tire meridian cross section shown in Figure 1 is defined as a cross section of the tire cut by a plane including the tire rotational axis (not shown). The tire equatorial plane CL is defined as a plane that passes through the midpoint of the tire section width defined by JATMA and is perpendicular to the tire rotational axis. The tire width direction is defined as the direction parallel to the tire rotational axis, and the inner side in the tire width direction refers to the side toward the tire equatorial plane CL in the tire width direction, and the outer side in the tire width direction refers to the side away from the tire equatorial plane CL in the tire width direction. The tire radial direction is defined as the direction perpendicular to the tire rotational axis, and the inner side in the tire radial direction refers to the side toward the tire rotational axis in the tire radial direction, and the outer side in the tire radial direction refers to the side away from the tire rotational axis in the tire radial direction. The tire circumferential direction refers to the direction around the tire rotational axis as the central axis.

[0012] The pneumatic tire 1 has an annular structure centered on the tire rotation axis, and as shown in FIG. 1, includes a pair of bead cores 11, a pair of bead fillers 12, a carcass layer 13, a belt layer 14, a tread rubber 15, a pair of sidewall rubbers 16, and a pair of rim cushion rubbers 17.

[0013] The pair of bead cores 11 are formed by winding one or more bead wires made of steel in an annular and multiply fashion, and are embedded in the bead portions to form the cores of the bead portions on both sides in the tire width direction.

[0014] The pair of bead fillers 12 are respectively arranged on the outer periphery of the pair of bead cores 11 in the tire radial direction to reinforce the bead portion.

[0015] The carcass layer 13 has a single-layer structure consisting of one carcass ply or a multi-layer structure consisting of multiple carcass plies stacked together. The carcass layer 13 is toroidally laid between the bead cores 11 on both sides in the tire width direction to form the tire framework. Both ends of the carcass layer 13 are wrapped around and secured to the outside in the tire width direction so as to enclose the bead cores 11 and the bead fillers 12. The carcass ply of the carcass layer 13 is formed by coating multiple carcass cords made of steel or organic fiber material (e.g., aramid, nylon, polyester, rayon, etc.) with coating rubber and rolling them. The carcass cords of the carcass layer 13 have a cord angle (defined as the inclination angle of the carcass cord in the longitudinal direction with respect to the tire circumferential direction) of 80 degrees or more and 100 degrees or less in absolute value.

[0016] The belt layer 14 is formed by laminating, for example, a plurality of belt plies 141 to 143, and is disposed by being wound around the outer periphery of the carcass layer 13. The belt plies 141 to 143 include, from the inner side in the tire radial direction, a pair of cross belts 141, 142 and a belt cover 143.

[0017] The pair of cross belts 141, 142 are formed by coating a plurality of belt cords made of steel or organic fiber material with coating rubber and rolling them. The cross belts 141, 142 have belt cords with an absolute cord angle (defined as the inclination angle of the belt cords in the longitudinal direction with respect to the tire circumferential direction) of 15 degrees or more and 55 degrees or less. The cross belts 141, 142 have belt cords with cord angles of opposite signs, and are layered with the longitudinal directions of the belt cords crossing each other (so-called cross-ply structure). The cross belts 141, 142 are layered and arranged on the outer side of the carcass layer 13 in the tire radial direction.

[0018] The belt cover 143 is formed by covering a belt cover cord made of steel or organic fiber material with coating rubber. In the belt cover 143, the belt cover cord has a cord angle (defined as the inclination angle of the belt cord in the longitudinal direction with respect to the tire circumferential direction) of 0 degrees or more and 10 degrees or less in absolute value. The belt cover 143 is, for example, a strip material formed by covering one or more belt cover cords with coating rubber, and is formed by spirally winding this strip material multiple times around the outer circumferential surfaces of the cross belts 141, 142 in the tire circumferential direction. The belt cover 143 is arranged to cover the entire area of ​​the cross belts 141, 142.

[0019] The tread rubber 15 is disposed on the outer periphery of the carcass layer 13 and the belt layer 14 in the tire radial direction to form the tread portion of the pneumatic tire 1. The tread rubber 15 is made of a rubber material that has excellent ground contact characteristics and weather resistance, and is exposed over the entire outer periphery of the tire to form the tread surface.

[0020] The pair of sidewall rubbers 16 are disposed on the outer sides of the carcass layer 13 in the tire width direction, and form sidewall portions on both sides in the tire width direction.

[0021] The pair of rim cushion rubbers 17 extend from the inner side in the tire radial direction to the outer side in the tire width direction of each bead core 11 and each turned-up portion of the carcass layer 13, and form the rim fitting surface of the bead portion.

[0022] FIG. 2 is a plan view showing the tire side portion 18 of the tire shown in FIG.

[0023] As shown in FIG. 2, the pneumatic tire 1 of the embodiment includes a marking portion 2 and a peripheral region 3 in a tire side portion 18.

[0024] The tire side portion 18 is a surface that continues uniformly from the ground contact edge T of the tread surface outward in the tire width direction and from the rim check line R outward in the tire radial direction, and is an annular surface that extends along the tire circumferential direction. The ground contact edges T refer to both outermost ends in the tire width direction in the region where the tread surface of the pneumatic tire 1 comes into contact with the road surface when the pneumatic tire 1 is mounted on a normal rim, inflated to the normal internal pressure, and subjected to 70% of the normal load, and continue in the tire circumferential direction. The rim check line R is a line used to check whether the tire is mounted properly on the rim, and is generally shown as a circular convex line that continues in the tire circumferential direction along the front side of the bead portion 10, radially outward of the rim flange 20a and near the rim flange 20a.

[0025] Here, the normal rim refers to the "applicable rim" defined by JATMA, the "design rim" defined by TRA, or the "measuring rim" defined by ETRTO. The normal internal pressure refers to the "maximum air pressure" defined by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" defined by TRA, or the "inflation pressures" defined by ETRTO. The normal load refers to the "maximum load capacity" defined by JATMA, the maximum value of the "tire load limits at various cold inflation pressures" defined by TRA, or the "load capacity" defined by ETRTO. In the case of the pneumatic tire 1 of the embodiment, the normal load is 88% of the maximum load capacity at the normal internal pressure.

[0026] The mark portion 2 includes a mark consisting of letters, figures, symbols, or a combination thereof, and particularly includes a trademark that functions as an identification sign indicating the tire manufacturer, tire brand, etc. Multiple mark portions 2 are arranged spaced apart in the tire circumferential direction. For example, in the configuration shown in FIG. 2 , a mark consisting of a combination of element 2A of the letters "YOKOHAMA" indicating the tire manufacturer and element 2B of a logo with a stylized "Y," the initial letter of the name, is applied to the surface of the tire side portion 18. A pair of mark portions 2 are arranged in opposing positions in the tire circumferential direction on the annular tire side portion 18.

[0027] The marking portion 2 has a radial height Ha [mm] of each element 2A relative to the tire cross-sectional height SH [mm] (see FIG. 1) in the range of 0.05≦Ha / SH≦0.80, and preferably in the range of 0.10≦Ha / SH≦0.70. This improves the visibility of the marking portion 2. The radial height Ha of the element 2A is measured as the maximum extension dimension of the element 2A in the tire radial direction.

[0028] The tire cross-sectional height SH is half the distance between the tire outer diameter and the rim diameter, and is measured with the pneumatic tire 1 mounted on a specified rim, a specified internal pressure applied, and no load applied.

[0029] The peripheral region 3 is a region surrounding the marking portion 2 and is formed on the surface of the tire side portion 18. The peripheral region 3 may be a smooth surface having a smooth surface, or may be an uneven surface that has been subjected to surface processing. In the embodiment, the peripheral region 3 is formed between a pair of narrow ribs 41, 42 that each extend in the tire circumferential direction and are positioned at different positions in the tire radial direction. This enhances the design of the tire side portion 18 of the pneumatic tire 1. Furthermore, the peripheral region 3 has an annular structure that extends around the entire circumference of the tire side portion 18 in the tire circumferential direction, and thus includes both of the pair of marking portions 2.

[0030] In the pneumatic tire 1 of the embodiment, the marking portion 2 and the peripheral region 3 are disposed radially outward of the tire maximum width position Ac. More specifically, the marking portion 2 and the peripheral region 3 are disposed in an area (see FIG. 1 ) from the tire ground contact edge T to the tire maximum width position Ac, with a pair of narrow ribs 41, 42 extending in the tire circumferential direction to define the peripheral region 3, and the marking portion 2 is disposed between these narrow ribs 41, 42. This increases the visibility of the marking portion 2 in the pneumatic tire 1. The pneumatic tire 1 is not limited to this configuration, and although not explicitly shown in the drawings, the marking portion 2 and the peripheral region 3 may be disposed within the tire side portion 18, including the tire maximum width position Ac, or may be disposed radially inward of the tire maximum width position Ac.

[0031] The tire maximum width position Ac is defined as the maximum width position of the tire section width within the tire side portion 18. The tire section width is measured as the linear distance in the tire width direction between the sidewalls, excluding irregularities such as the marking portion 2, the peripheral region 3, and patterns and letters such as the narrow ribs 41, 42 on the surface of the tire side portion 18, when the tire is mounted on a specified rim, pressurized to a specified internal pressure, and in an unloaded state.

[0032] The fine ribs 41, 42 have a width of 0.4 mm to 0.8 mm and a height from the surface of the tire side portion 18 of 0.1 mm to 1.0 mm, and function as a discharge path for residual air during tire vulcanization. This reduces the occurrence of vulcanization defects in the marking portion 2 and the surrounding area 3 of the pneumatic tire 1. In addition, in the pneumatic tire 1 of the embodiment, the fine rib 41 on the outer side in the tire radial direction is located at a mold split position of the tire molding die.

[0033] Furthermore, the marking portion 2 has a radial height Ha [mm] of the element 2A, relative to the spacing Hb [mm] of the fine ribs 41, 42 in the tire radial direction, in the range of 0.30≦Ha / Hb≦0.80, and preferably in the range of 0.40≦Ha / Hb≦0.70. Furthermore, in the pneumatic tire 1 of the embodiment, it is preferable that the marking portion 2 is disposed away from the pair of fine ribs 41, 42, as shown in Fig. 2. As a result, the visibility of the marking portion 2 in the pneumatic tire 1 is improved.

[0034] 3, 5, and 7 are enlarged views of a portion of the marking portion 2 of the tire side portion 18 shown in FIG. 2. FIG. 4 is a cross-sectional view (a cross-sectional view taken along line AA in FIG. 3) of a portion of the marking portion 2 shown in FIG. 3. FIG. 6 is a cross-sectional view (a cross-sectional view taken along line BB in FIG. 5) of a portion of the marking portion 2 shown in FIG. 7. FIG. 8 is a cross-sectional view (a cross-sectional view taken along line CC in FIG. 7) of a portion of the marking portion 2 shown in FIG. 7. In FIGS. 3 to 8, the ridges 7 arranged in the pattern portion 4 are simplified by hatching for convenience.

[0035] In the pneumatic tire 1 shown in Figures 3 and 4, the marking portion 2 (element 2A) is formed as a recessed portion 5 that is recessed into the peripheral region 3 in the tire side portion 18. That is, the marking portion 2 (element 2A) is formed such that the inner wall surface of the recessed portion 5 forms the contour line. In this pneumatic tire 1, the surface that forms the peripheral region 3 is a smooth surface, and a pattern portion 4, which will be described below, is provided on the smooth tire surface 5A that is the inner bottom of the recessed portion 5 of the marking portion 2 (element 2A).

[0036] In the pneumatic tire 1 shown in FIGS. 5 and 6, in the tire side portion 18, the marking portion 2 (element 2A) is formed as a convex portion 6 that protrudes from the surface with respect to the peripheral region 3. That is, the marking portion 2 (element 2A) is formed with the outer wall surface of the convex portion 6 as a contour line. In this pneumatic tire 1, the surface forming the protruding end of the convex portion 6 is a smooth surface, and a pattern portion 4, which will be described below, is provided around the convex portion 6 of the marking portion 2 (element 2A) on the tire surface 3A of the smooth peripheral region 3 (tire side portion 18).

[0037] In the pneumatic tire 1 shown in FIGS. 7 and 8, in the tire side portion 18, the marking portion 2 (element 2A) is formed as a convex portion 6 that protrudes from the surface with respect to the peripheral region 3. That is, the marking portion 2 (element 2A) is formed with the outer wall surface of the convex portion 6 as a contour line. In this pneumatic tire 1, the surface forming the protruding end of the convex portion 6 is a smooth surface, and a pattern portion 4, which will be described below, is provided on the tire surface 3A of the smooth peripheral region 3 (tire side portion 18) around the outer wall surface of the convex portion 6 of the marking portion 2 (element 2A).

[0038] Fig. 9 is a plan view of the pattern section 4. Fig. 10 is a detailed view of part D in Fig. 9. Fig. 11 is a partially enlarged cross-sectional view of the pattern section 4 (cross-sectional view taken along E-E in Fig. 10).

[0039] When the pattern portion 4 is formed on the tire surface 5A, which is the bottom surface of the recessed portion 5 that forms the outline of the marking portion 2 (element 2A) as shown in Figures 3 and 4, the pattern portion 4 is arranged at a position recessed from the peripheral region 3 as shown in Figure 11. When the pattern portion 4 is formed on the tire surface 3A in the peripheral region 3, which is around the protruding portion 6 that forms the outline of the marking portion 2 (element 2A) as shown in Figures 5 to 8, the pattern portion 4 is arranged at a position recessed from the protruding portion 6 as shown in Figure 11.

[0040] In the pattern portion 4 (4A) shown in Figures 9 and 10, continuous ridges 7 are arranged. That is, in the pattern portion 4 (4A), continuous ridges 7 are arranged in a single stroke. The pattern portion 4A (4) is made up of continuous ridges 7 arranged based on a curve having self-similarity. Self-similarity here means that the overall structure of the pattern portion 4A (4) formed by the continuous ridges 7 is similar to the partial structure. That is, the pattern portion 4A (4) is made up of a so-called fractal curve, in which the parts of the pattern portion 4A (4) are self-similar to the whole.

[0041] In this embodiment, the ridges 7 constituting the pattern portion 4A(4) are arranged based on a Sierpinski curve, which is also configured as a space-filling curve that passes through all unit squares in a two-dimensional plane and can fill the space on the two-dimensional plane, and the ridges 7 of the pattern portion 4A(4) are arranged based on the space-filling curve.

[0042] Here, we will explain the Sierpinski curve, which is an example of a fractal curve. FIG. 12 is an explanatory diagram of the Sierpinski curve. For the Sierpinski curve S, the regression 1 curve S1 shown in FIG. 12(b) can be obtained by performing a recursive process on the Sierpinski curve S once for the initial value S0 shown in FIG. 12(a). Similarly, the regression 2 curve S2 shown in FIG. 12(c) can be obtained by performing the recursive process twice, and the regression 3 curve S3 shown in FIG. 12(d) can be obtained by performing the recursive process three times. In the pattern portion 4A(4), continuous ridges 7 are arranged based on the Sierpinski curve formed by repeating these recursive processes.

[0043] Specifically, the ridge 7 constituting the pattern portion 4A(4) has multiple linear portions 7A extending linearly and multiple bent portions 7B connecting the linear portions 7A. The bent portions 7B are portions where the linearly extending ridge 7 bends in the width direction of the ridge 7. In the ridges 7 arranged based on the Sierpinski curve, the relative angle θ between the linear portions 7A connected by the bent portions 7B is 90° or 135°. That is, the angle θ on the minor angle side of the bent portions 7B is 90° or 135°. Therefore, the ridges 7 constituting the pattern portion 4A(4) are arranged by combining multiple linear portions 7A, multiple bent portions 7B bent at 90°, and multiple bent portions 7B bent at 135°. In the pattern portion 4A(4), the bent angles θ of the bent portions 7B are 90° or 135°, so that the linear portions 7A extend in four directions.

[0044] The straight portions 7A of the ridge 7 do not have to extend strictly straight, and the straight portions 7A may be slightly curved. The bending angle of the bent portions 7B of the ridge 7 does not have to be strictly 90° or 135°, and the bending angle of the bent portions 7B may be approximately 90° or 135°. The bent portions 7B of the ridge 7 do not have to be strictly curved, and may be curved. That is, the bent portions 7B may connect the straight portions 7A in a curved shape. Even when the bent portions 7B are curved, the direction of extension of the ridge 7 gradually changes, so that the relative angle θ between the straight portions 7A connected by the bent portions 7B is 90° or 135°.

[0045] The ridges 7 constituting the pattern portion 4A(4) formed in this manner are rib-like protrusions protruding from the tire surfaces 3A, 5A, and are formed with a triangular cross-sectional shape that narrows from a base 7E of the tire surfaces 3A, 5A toward an apex 7D, as shown in Fig. 11. It is preferable that the apex 7D of the ridges 7 be pointed.

[0046] The ridges 7 constituting the pattern portion 4 preferably have a width W of the largest base 7E in the range of 0.03 mm to 0.5 mm. The width W of the ridges 7 is measured as the width in a cross section perpendicular to the direction in which the ridges 7 extend. Furthermore, the pitch P between the peaks 7D of adjacent ridges 7 is preferably 0.5 mm or less, and more preferably 0.25 mm or less. In this way, the pattern portion 4 in which the width W and pitch P of the ridges 7 are specified can improve the processability of the pneumatic tire 1 without hindering removal from the tire mold.

[0047] As described above, when the ridges 7 constituting the pattern portion 4 are formed on the tire surface 5A, which is the bottom surface of the recessed portions 5 constituting the outline of the marking portion 2 (element 2A), they are arranged in a position recessed from the peripheral region 3 as shown in Fig. 11. Furthermore, when the ridges 7 constituting the pattern portion 4 are formed on the tire surface 3A in the peripheral region 3, which is around the protruding portions 6 constituting the outline of the marking portion 2 (element 2A), as described above, they are arranged in a position recessed from the protruding portions 6 as shown in Fig. 11. In this configuration, as shown in Fig. 11, the height T of the ridges 7 from the tire surface 5A, 3A to the peaks 7D is preferably in the range of 0.1 mm to 1.5 mm, and more preferably in the range of 0.2 mm to 1.3 mm.

[0048] Thus, a pattern portion 4 having a height T of ridges 7 set to the above height T can improve the processability of a pneumatic tire 1 without hindering removal from a tire mold. Furthermore, as shown in FIG. 11 , the height T of ridges 7 from tire surfaces 5A, 3A to peaks 7D is preferably in the range of 0.5≦T / T0<1.0, and more preferably in the range of 0.7≦T / T0≦0.95, relative to the height T0 of recesses 5 and the height T0 of protrusions 6. A pattern portion 4 having this configuration can prevent foreign matter from coming into contact with ridges 7 and thus prevent damage to ridges 7, due to the height T0 of recesses 5 and the height T0 of protrusions 6.

[0049] This pneumatic tire 1 is manufactured using a tire molding die capable of transferring the above-described pattern portion 4 (4A) onto the surface of the tire side portion 18.

[0050] Specifically, the pneumatic tire 1 is manufactured, for example, by the following manufacturing process. First, tire components such as the bead wires that form the bead core 11, the carcass plies that form the carcass layer 13, the belt plies 141 to 143 that form the belt layer 14, the tread rubber 15, the sidewall rubber 16, and the rim cushion rubber 17 are placed in a molding machine to form a green tire (not shown). Next, the green tire of the pneumatic tire 1 is filled into a tire vulcanization mold (not shown) that includes a tire molding die. Next, the green tire of the pneumatic tire 1 is expanded radially outward by a pressure device and abuts against the tire molding die. Next, the tire vulcanization mold is heated, and rubber molecules of the green tire are bonded with sulfur molecules, thereby progressing vulcanization of the pneumatic tire 1. At this time, the shape of the molding surface of the tire molding die is transferred to the outer peripheral surface of the green tire, and the surface of the tire side portion 18 of the pneumatic tire 1 is formed. The tire after vulcanization is then removed from the tire vulcanization mold.

[0051] The pattern portion 4 (4A) on the tire surface 3A, 5A is formed by irregularities formed on the molding surface of the tire molding mold. The irregularities on the molding surface of the tire molding mold are formed, for example, by laser processing. That is, in the tire molding mold, the irregularities on the molding surface are formed by laser processing grooves for forming ridges 7 in the form of Sierpinski curves with multiple straight portions 7A and multiple bent portions 7B. Furthermore, since the pattern portion 4 (4A) is formed in a unicursal shape by the continuous ridges 7, each groove for forming the pattern portion 4 (4A) is formed by continuous laser processing.

[0052] A tire molding die in which grooves are formed by laser processing can mold the pattern portion 4 (4A) having the above-described shape. Furthermore, a tire molding die in which grooves are formed by laser processing has a rougher processed surface than a machined one, so that even the pattern portion 4 (4A) having the above-described shape can be easily demolded, which contributes to improving the productivity of pneumatic tires 1.

[0053] In the pneumatic tire 1 of the embodiment, the pattern portion 4A(4) arranged on the tire surface 3A, 5A is formed by continuous ridges 7 arranged based on self-similar curves. Therefore, the pattern portion 4A(4) can reduce variations in the density of the ridges 7, achieving a uniform arrangement density, and can arrange the ridges 7 so that they face in multiple directions. This allows the pattern portion 4A(4) to disperse and reflect irradiated light using the ridges 7, preventing light irradiated to the pattern portion 4A(4) from being reflected in a uniform direction. By preventing light from being reflected in a uniform direction in this way, the pattern portion 4A(4) is blackened to make it appear black, thereby clarifying the contrast between the pattern portion 4A(4) and other areas without the pattern portion 4A(4). As a result, the visibility of the pattern portion 4A(4) can be improved.

[0054] Furthermore, because the ridges 7 that make up the pattern portion 4A(4) are arranged based on a space-filling curve, the density of the ridges 7 per unit area can be increased. This allows the light irradiated onto the pattern portion 4A(4) to be more dispersed and reflected by the ridges 7 arranged at a high density. Therefore, the pattern portion 4A(4) can be blackened to clearly contrast with other areas where the pattern portion 4A(4) is not present. As a result, the visibility of the pattern portion 4A(4) can be improved.

[0055] Furthermore, the ridges 7 constituting the pattern portion 4A(4) have multiple straight portions 7A and multiple bent portions 7B, and the relative angles between the straight portions 7A connected by the bent portions 7B are 90° or 135°, so the orientation of the ridges 7 can be more reliably arranged to face multiple directions. This allows light irradiated onto the pattern portion 4A(4) to be more reliably dispersed and reflected by the ridges 7 arranged facing multiple directions. Therefore, the pattern portion 4A(4) can be blackened to clearly contrast with other areas where the pattern portion 4A(4) is not present. As a result, the visibility of the pattern portion 4A(4) can be improved.

[0056] Furthermore, because the ridges 7 that make up the pattern portion 4A(4) are arranged based on the Sierpinski curve, the ridges 7 can be arranged at an equal density and oriented in multiple directions regardless of the size of the pattern portion 4A(4). This allows the ridges 7 to disperse and reflect irradiated light regardless of the size of the pattern portion 4A(4), turning the pattern portion 4A(4) black and creating a clear contrast with other areas where the pattern portion 4A(4) is not present. As a result, the visibility of the pattern portion 4A(4) can be improved.

[0057] Furthermore, in the pattern portion 4A(4), the width W of the ridges 7 is within a range of 0.03 mm to 0.5 mm, and the pitch P between adjacent ridges 7 is 0.5 mm or less. Therefore, as shown in FIG. 11 , in the pattern portion 4A(4), light L incident between adjacent ridges 7 is absorbed by multiple reflections from the apex 7D of the ridge 7 toward the base 7E and toward the tire surface 5A, 3A, causing the pattern portion 4A(4) to appear black. This clarifies the contrast between the pattern portion 4A(4) and other areas where the pattern portion 4A(4) is not present. As a result, the visibility of the pattern portion 4A(4) is improved, and the visibility of the marking portion 2 applied to the tire side portion 18 is also improved.

[0058] Furthermore, when the pattern portion 4A(4) is provided on the inner bottom of the recess 5 of the marking portion 2 recessed from the peripheral region 3 formed on the surface of the tire side portion 18, the pattern portion 4A(4) can make the marking portion 2 recessed from the peripheral region 3 stand out. As a result, the visibility of the marking portion 2 provided on the tire side portion 18 can be improved.

[0059] Furthermore, when the pattern portion 4A(4) is provided around the protrusion 6 of the mark portion 2 protruding from the peripheral region 3, the mark portion 2 protruding from the peripheral region 3 can be made to stand out by the highly visible pattern portion 4A(4) that is arranged around the mark portion 2. As a result, the visibility of the mark portion 2 provided on the tire side portion 18 can be improved.

[0060] Furthermore, when the pattern portion 4A(4) is provided to outline the protrusion 6 of the marking portion 2 protruding from the peripheral region 3, the marking portion 2 protruding from the peripheral region 3 can be made to stand out by being outlined with the highly visible pattern portion 4A(4). As a result, the visibility of the marking portion 2 provided on the tire side portion 18 can be improved.

[0061] [Variations] In the above-described embodiment, the ridges 7 constituting the pattern portion 4 are arranged based on the Sierpinski curve, but the ridges 7 of the pattern portion 4 may be arranged in a form other than the Sierpinski curve.

[0062] Fig. 13 is an explanatory diagram showing a pattern portion 4B that is a modified example of the pneumatic tire 1 according to the embodiment and is different from the embodiment. The ridges 7 that make up the pattern portion 4B(4) may be arranged in a form similar to a Sierpinski curve, for example, as shown in Fig. 13. In the pattern portion 4B(4) shown in Fig. 13, the ridges 7 have multiple straight portions 7A and multiple bent portions 7B with bend angles of 90° or 135°, and are arranged in a form similar to a Sierpinski curve.

[0063] In this way, by arranging the ridges 7 of the pattern portion 4B(4) in a form similar to a Sierpinski curve, it is possible to equalize the arrangement density of the ridges 7 and arrange the ridges 7 so that they face in multiple directions. This allows the ridges 7 to disperse and reflect light irradiated onto the pattern portion 4B(4), turning the pattern portion 4B(4) black, thereby improving the visibility of the pattern portion 4B(4).

[0064] Furthermore, in the above-described embodiment, the ridges 7 constituting the pattern portion 4 are arranged based on the Sierpinski curve, which is an example of a curve having self-similarity, but the ridges 7 may be arranged based on a curve other than the Sierpinski curve. The ridges 7 may be arranged based on, for example, a Peano curve, a Hilbert curve, or a Gosper curve. By arranging the ridges 7 constituting the pattern portion 4 based on a fractal curve having self-similarity, the density of the arrangement of the ridges 7 is reduced and the ridges 7 can be arranged to face in multiple directions. This allows the ridges 7 to disperse and reflect irradiated light, thereby improving the visibility of the pattern portion 4.

[0065] In the present embodiment, as described above, a pneumatic tire 1 has been described as an example of a tire. The pneumatic tire 1 can be filled with air, an inert gas such as nitrogen, or other gases. However, the configuration of the pattern portion of the pneumatic tire 1 described in the present embodiment can be arbitrarily applied to other tires within the scope of what is obvious to those skilled in the art. Examples of other tires include airless tires and solid tires.

[0066] The present disclosure includes the following inventions. Invention[1] A tire characterized by having a pattern portion on the tire surface, the pattern portion being made up of continuous ridges arranged based on self-similar curves. Invention[2] the ridge has a plurality of linear portions extending linearly and a plurality of bent portions connecting the linear portions, The tire according to the invention [1], wherein the relative angle between the straight portions connected by the bent portions is 90° or 135°. Invention[3] The tire according to the invention [1] or [2], wherein the ridges are arranged based on a Sierpinski curve. Invention[4] The pattern portion is A tire according to any one of inventions [1] to [3], wherein the width of the ridge is 0.03 mm or more and 0.5 mm or less, and the pitch between adjacent ridges is 0.5 mm or less. Invention[5] The pattern portion is A tire according to any one of inventions [1] to [4], wherein the marking is provided on the inner bottom of a recess in the tire sidewall that is recessed from the surface of the tire sidewall. Invention[6] The pattern portion is A tire according to any one of inventions [1] to [4], which is provided around the convex portion of the marking portion protruding from the surface of the tire side portion. Invention[7] The pattern portion is A tire according to any one of inventions [1] to [4], wherein the marking is provided around a convex portion of the marking portion that protrudes from the surface of the tire side portion. [Explanation of symbols]

[0067] 1 pneumatic tire 2. Emblem Section 2A, 2B elements 3. Surrounding Areas 3A, 5A tire surface 4(4A, 4B) Pattern section 5 recess 6 Convex part 7 Ridge 7A Straight section 7B Bent part 7D Top 7E base 10 Bead section 11 Bead core 12 Bead filler 13 Carcass layer 14 Belt Layer 15 Tread rubber 16 Sidewall rubber 17 Rim cushion rubber 18 Tire side 20 rims 20a rim flange 41, 42 Thin rib

Claims

1. A tire characterized by having a pattern portion on the tire surface, the pattern portion being made up of continuous ridges arranged based on self-similar curves.

2. the ridge has a plurality of linear portions extending linearly and a plurality of bent portions connecting the linear portions, The tire according to claim 1 , wherein the relative angle between the straight portions connected by the bent portion is 90° or 135°.

3. 10. The tire of claim 1, wherein the ridges are arranged according to a Sierpinski curve.

4. The pattern portion is 2. The tire according to claim 1, wherein the width of the ridge is 0.03 mm or more and 0.5 mm or less, and the pitch between adjacent ridges is 0.5 mm or less.

5. The pattern portion is 2. The tire according to claim 1, wherein the marking is provided on the inner bottom of a recessed portion recessed from the surface of the tire side portion.

6. The pattern portion is The tire according to claim 1, wherein the marking is provided around a protrusion of the marking protruding from the surface of the tire side portion.

7. The pattern portion is 2. The tire according to claim 1, wherein the marking is provided by edging a convex portion of the marking that protrudes from the surface of the tire side portion.

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