Tire

Abstract

The present invention improves the visibility of a patterned portion. This tire comprises a patterned portion (4) formed from one continuous ridge (7A), which is disposed on the tire surface on the basis of a space-filling curve.

Description

tire

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

[0002] For example, Patent Document 1 discloses a tire that provides improved visibility of a decorative portion provided on a sidewall portion while the tire is in motion. In this tire, a decorative strip formed from a ridge on the sidewall portion has a decorative element formed by repeating a repeating element, and the decorative element extends continuously without interruption. The repeating element is composed of a plurality of straight portions and a plurality of connecting portions connecting the straight portions, and the plurality of straight portions have two to six different directions.

[0003] Japanese Patent Application Laid-Open No. 2017-013619

[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] An object of the present invention is to provide a tire that can improve the visibility of a pattern portion.

[0006] In order to achieve the above object, a tire according to one aspect of the present invention includes a pattern portion on the tire surface, the pattern portion being made up of a single continuous ridge arranged based on a space-filling curve.

[0007] The present invention can improve the visibility of the pattern portion.

[0008] FIG. 1 is a cross-sectional view of a pneumatic tire according to an embodiment in the tire meridian direction. FIG. 2 is a plan view showing a tire side portion of the tire shown in FIG. 1. FIG. 3 is an enlarged view of a portion of a marking portion of the tire side portion shown in FIG. 2. FIG. 4 is a cross-sectional view of a portion of the marking portion shown in FIG. 3. FIG. 5 is an enlarged view of a portion of a marking portion of the tire side portion shown in FIG. 2. FIG. 6 is a cross-sectional view of a portion of the marking portion shown in FIG. 5. FIG. 7 is an enlarged view of a portion of a marking portion of the tire side portion shown in FIG. 2. FIG. 8 is a cross-sectional view of a portion of the marking portion shown in FIG. 7. FIG. 9 is an explanatory diagram of a pattern portion. FIG. 10 is an explanatory diagram of a pattern portion. FIG. 11 is an explanatory diagram of a pattern portion. FIG. 12 is a partially enlarged cross-sectional view of the pattern portion. FIG. 13 is an explanatory diagram of another example of the pattern portion. FIG. 14 is an explanatory diagram of another example of the pattern portion. FIG. 15 is an explanatory diagram of another example of the pattern portion.

[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] Fig. 1 is a cross-sectional view of a pneumatic tire according to an embodiment in the tire meridian direction. Fig. 1 shows a cross-sectional view of one side region in the tire radial direction of a pneumatic tire 1 mounted on a rim 20. In the embodiment, a pneumatic tire, specifically 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 cross-sectional width defined by JATMA and is perpendicular to the tire rotational axis. The tire width direction is defined as a direction parallel to the tire rotational axis, and the tire width direction inner side refers to the side toward the tire equatorial plane CL in the tire width direction, and the tire width direction outer side refers to the side away from the tire equatorial plane CL in the tire width direction. The tire radial direction is defined as a direction perpendicular to the tire rotational axis, and the tire radial direction inner side refers to the side toward the tire rotational axis in the tire radial direction, and the tire radial direction outer side 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 anchored outward in the tire width direction 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 in 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 belt cords of the cross belts 141, 142 have a cord angle (defined as the inclination angle of the belt cords in the longitudinal direction relative to the tire circumferential direction) of 15 degrees or more and 55 degrees or less in absolute value. The cross belts 141, 142 have belt cords with cord angles of opposite signs, and are layered with the belt cords' longitudinal directions crossing each other (a so-called cross-ply structure). The cross belts 141, 142 are layered 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. The belt cover cord of the belt cover 143 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 wrapping this strip material around the outer peripheral surfaces of the cross belts 141, 142 multiple times 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 a tire side portion 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 uniformly continuous surface extending in the tire circumferential direction 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. 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 are continuous in the tire circumferential direction. The rim check line R is a line used to check whether the tire is properly mounted 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 20 a and near the rim flange 20 a.

[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 marking 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 marking 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 character string "YOKOHAMA" indicating the tire manufacturer and element 2B of a logo with a stylized "Y," the initial letter of the word, is applied to the surface of the tire side portion 18. A pair of marking 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, preferably 0.10≦Ha / SH≦0.70, thereby improving the visibility of the marking portion 2. The radial height H2 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 when the pneumatic tire 1 is mounted on a specified rim, a specified internal pressure is applied, and the tire is in an unloaded state.

[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 extends in the tire circumferential direction and is formed between a pair of narrow ribs 41, 42 that 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 thereby includes both of the pair of marking portions 2.

[0030] In the pneumatic tire 1 of this embodiment, the marking portion 2 and the peripheral region 3 are positioned radially outward of the tire maximum width position Ac. More specifically, the marking portion 2 and the peripheral region 3 are formed by a pair of narrow ribs 41, 42 extending in the tire circumferential direction so as to define the peripheral region 3 in the region from the tire ground contact edge T to the tire maximum width position Ac (see FIG. 1 ), with the marking portion 2 being positioned 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 positioned within the tire side portion 18, including the tire maximum width position Ac, or may be positioned 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 thin 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 the pneumatic tire 1 of the embodiment, the thin 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 radial height Ha [mm] of the element 2A of the marking portion 2 is in the range of 0.30≦Ha / Hb≦0.80, and preferably 0.40≦Ha / Hb≦0.70, relative to the arrangement interval Hb [mm] of the fine ribs 41, 42 in the tire radial direction. Furthermore, in the pneumatic tire 1 of the embodiment, it is preferable that the marking portion 2 is arranged 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] Figures 3, 5, and 7 are enlarged views of a portion of the marking portion on the tire side shown in Figure 2. Figure 4 is a cross-sectional view (A-A cross-sectional view in Figure 3) of a portion of the marking portion shown in Figure 3. Figure 6 is a cross-sectional view (B-B cross-sectional view in Figure 5) of a portion of the marking portion shown in Figure 5. Figure 8 is a cross-sectional view (C-C cross-sectional view in Figure 7) of a portion of the marking portion shown in Figure 7.

[0035] 3 and 4 , in the tire side portion 18, the marking portion 2 (element 2A) is formed as a recessed portion 5 that is recessed relative to the peripheral region 3. That is, the marking portion 2 (element 2A) is formed such that the inner wall surface of the recessed portion 5 forms a 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] 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] 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 relative 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] 9 to 11 are explanatory diagrams of the pattern portion. Fig. 12 is a partially enlarged cross-sectional view of the pattern portion (cross-sectional view taken along line D-D in Fig. 10). Fig. 9 shows one section 71 described below, while Figs. 10 and 11 show multiple sections 71, with Fig. 11 showing a wider area than 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 12. When the pattern portion 4 is formed on the tire surface 3A in the peripheral region 3 that 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 12.

[0040] The pattern portion 4A(4) shown in FIGS. 9 to 11 has a section 71.

[0041] The section 71 has a ridge 7A.

[0042] As shown in Fig. 12, the ridges 7A are rib-like protrusions that protrude from the tire surfaces 3A and 5A and are formed with a triangular cross-sectional shape that narrows from a base 7Ab on the tire surfaces 3A and 5A toward an apex 7Aa. The apex 7Aa of the ridges 7A is preferably pointed. As shown in Figs. 9, 10, and 12, the width W of the ridges 7A at their widest point, at their base 7Ab, is preferably in the range of 0.03 mm to 0.5 mm. The width W of the ridges 7A is measured as the width in a cross section perpendicular to the direction in which the ridges 7A extend.

[0043] As described above, when the ridges 7A constituting the pattern portion 4A 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 positioned at a position recessed from the peripheral region 3 as shown in FIG. 12 . Furthermore, when the ridges 7A 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 positioned at a position recessed from the protruding portions 6 as shown in FIG. 12 . In this configuration, as shown in FIG. 12 , the height T of the ridges 7A from the tire surface 5A, 3A to their peaks 7Aa 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. In this way, the pattern portion 4 with the ridges 7A having the height T can improve the processability of the pneumatic tire 1 without interfering with the release of the pneumatic tire from a tire mold. 12 , the height T of the ridge 7A from the tire surface 5A, 3A to the peak 7Aa 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 the recessed portions 5 and the height T0 of the protruding portions 6. In the pattern portion 4 configured in this manner, the height T0 of the recessed portions 5 and the height T0 of the protruding portions 6 can prevent foreign matter from coming into contact with the ridge 7A and prevent damage to the ridge 7A.

[0044] As shown in FIG. 9 , in the pattern portion 4A, one section 71 is composed of line segments 71A and curved portions 71B formed by the above-described ridges 7A. The line segments 71A are primarily formed as straight lines, but may also be formed as curved portions. The curved portions 71B are formed as bending points between two line segments 71A where the direction of extension of each line segment 71A changes. The bending of the curved portions 71B is not limited to being angular, and may also be formed as arcs. Specifically, in the pattern portion 4A, one section 71 is composed of five line segments 71A and four curved portions 71B. When viewed in a plane toward the tire surfaces 3A and 5A (planar view), one line segment 71A divides the plane into multiple squares 61 and is positioned so as to straddle two adjacent squares 61. The curved portions 71B are positioned as bending points between two line segments 71A that change direction within one square 61. In section 71, curved portion 71B is positioned as a bending point between two line segments 71A that change direction at a right angle. Section 71 is positioned in the nine-divided square 61, with five line segments 71A and four curved portions 71B arranged in a shape that combines two U-shaped shapes that open in opposite directions. The shape of this section 71 is called a Peano curve, which is a space-filling curve that is a single continuous curve.

[0045] As shown in FIG. 10 , the pattern portion 4A is formed by connecting multiple sections 71, with their ends aligned, rotated, or inverted, via connecting portions 71C, forming a single continuous curve. In this pattern portion 4A, the pitch P between the peaks 7Aa of adjacent ridges 7A is preferably 0.5 mm or less, and more preferably 0.25 mm or less. Thus, the pattern portion 4, with the width W and pitch P of the ridges 7A defined as described above, is formed as grooves in a tire molding die, improving the processability of the pneumatic tire 1 without hindering the escape of rubber from the grooves. As shown in FIGS. 10 and 11 , the pattern portion 4A is formed with the same pitch P at each position of the adjacent ridges 7A, resulting in a large number of continuous sections 71, with no spacing between the ridges 7A.

[0046] The pattern portion 4B(4) shown in FIGS.

[0047] The section 72 has a ridge 7A. The ridge 7A is configured in the same manner as the pattern section 4A, and therefore a description thereof will be omitted.

[0048] As shown in FIG. 13 , in the pattern portion 4B, one section 72 is composed of line segments 72A and curved portions 72B formed by the above-described ridges 7A. The line segments 72A are primarily formed as straight lines, but may also be formed as curved portions. The curved portions 72B are formed as bending points between two line segments 72A where the direction of extension of each line segment 72A changes. The bending of the curved portions 72B is not limited to being angular, and may also be formed as arcs. Specifically, in the pattern portion 4B, one section 72 is composed of three line segments 72A and two curved portions 72B. When viewed in a plane toward the tire surfaces 3A and 5A (planar view), one line segment 72A divides the plane into multiple squares 61 and is positioned so as to straddle two adjacent squares 61. The curved portions 72B are positioned as bending points between two line segments 72A that change direction within one square 61. In section 72, curved portion 72B is positioned as a bending point between two line segments 72A that change direction at a right angle. Section 72 is positioned in the square 61 divided into four, with three line segments 72A and two curved portions 72B combined to form a single U-shape. The shape of section 72 is called a Hilbert curve, which is a space-filling curve that is a single continuous curve.

[0049] As shown in Figure 14, the pattern portion 4B is formed by connecting multiple sections 72, with their ends aligned, rotated, or inverted, via connecting portions 72C, to form a single continuous curve. In this pattern portion 4B, the pitch P between the peaks 7Aa of adjacent ridges 7A is preferably 0.5 mm or less, and more preferably 0.25 mm or less. Thus, the pattern portion 4, with the width W and pitch P of the ridges 7A defined as described above, is formed as grooves in a tire molding die, improving the processability of the pneumatic tire 1 without hindering the escape of rubber from these grooves. As shown in Figures 14 and 15, the pattern portion 4A is formed with the same pitch P at each position of the adjacent ridges 7A, resulting in a large number of continuous sections 72, with no density variation between the ridges 7A.

[0050] The pneumatic tire 1 is manufactured using a tire molding die that can transfer the above-described pattern portion 4 onto the surface of the tire side portion 18 .

[0051] 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 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 bond 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.

[0052] Furthermore, the pattern portion 4 on the tire surface 3A, 5A described above is formed by irregularities formed on the molding surface of the tire mold. The irregularities on the molding surface of the tire mold are formed, for example, by laser processing. That is, in the tire mold, the irregularities on the molding surface are formed by laser processing to form grooves corresponding to the ridges 7A. A tire mold in which grooves are formed by laser processing can mold the ridges 7A having the above-described shape. Furthermore, a tire mold in which grooves are formed by laser processing has surface roughness on the processed surface compared to a machined tire mold, which improves the mold release properties of the ridges 7A and contributes to improving the productivity of the pneumatic tire 1. Furthermore, a configuration in which sections 71 of the same shape are continuous, as in the pattern portion 4 of the embodiment, also improves mold release properties and contributes to improving the productivity of the pneumatic tire 1.

[0053] A feature of the pneumatic tire 1 of the embodiment is that it includes a pattern portion 4 on the tire surfaces 3A, 5A, which is made up of a single continuous ridge 7A arranged based on a space-filling curve (sections 71, 72). Therefore, as shown in Fig. 12 , in this pneumatic tire 1, light L incident between the ridges 7A is absorbed as it travels toward the tire surfaces 5A, 3A while being reflected multiple times from the peaks 7Aa toward the bases 7Ab, causing the pattern portion 4 to appear black, thereby clarifying the contrast, which is the difference in light and dark between the pattern portion 4 and other parts without the pattern portion 4, and improving the visibility of the marking portion 2 applied to the tire side portion 18.

[0054] Furthermore, in the pneumatic tire 1 of the embodiment, the density variation between the ridges 7A is reduced by arranging them based on a space-filling curve, so that the contrast is made clearer by blackening in response to light L incident from different directions, thereby improving visibility.

[0055] Moreover, in the pneumatic tire 1 of the embodiment, the pattern portion 4 is made up of a single continuous ridge 7A, so that the entire pattern portion 4 can be easily formed.

[0056] In the pneumatic tire 1 of the embodiment, the ridges 7A are arranged based on a Peano curve or a Hilbert curve. Therefore, the pneumatic tire 1 can achieve a single continuous configuration with reduced variation in density between the ridges 7A.

[0057] In the pneumatic tire 1 of the embodiment, the width W of the ridges 7A in the pattern portion 4 is 0.03 mm or more and 0.5 mm or less, and the pitch P between adjacent ridges 7A is 0.5 mm or less. Therefore, the pneumatic tire 1 has a remarkable effect of clarifying contrast and improving visibility by the black color.

[0058] Furthermore, in the pneumatic tire 1 of the embodiment, the pattern portion 4 is provided on the inner bottom of the recessed portion 5 of the marking portion 2. Furthermore, in the pneumatic tire 1 of the embodiment, the pattern portion 4 is provided around the convex portion 6 of the protruding marking portion 2. Furthermore, in the pneumatic tire 1 of the embodiment, the pattern portion 4 is provided to frame the convex portion 6 of the protruding marking portion 2. Therefore, in this pneumatic tire 1, the effect of clarifying contrast and improving visibility by using black can make the marking portion 2 stand out in various ways.

[0059] In the present embodiment, as described above, the 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.

[0060] The present disclosure includes the following inventions. [Invention 1] A tire comprising, on its surface, a pattern portion consisting of a single continuous ridge arranged based on a space-filling curve. [Invention 2] The tire according to Invention 1, in which the ridges are arranged based on a Peano curve or a Hilbert curve. [Invention 3] The tire according to Invention 1 or 2, in which the ridge width of the pattern portion 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 4] The tire according to any one of Inventions 1 to 3, in which the pattern portion is provided on the inner bottom of a recess in a recessed marking portion. [Invention 5] The tire according to any one of Inventions 1 to 3, in which the pattern portion is provided around a convex portion of a protruding marking portion. [Invention 6] The tire according to any one of Inventions 1 to 3, in which the pattern portion is provided to frame the convex portion of the protruding marking portion.

[0061] REFERENCE SIGNS LIST 1 pneumatic tire (tire) 2 marking portion 3A, 5A tire surface 4 (4A, 4B) pattern portion 5 recessed portion 6 protruding portion 7A ridge

Claims

1. A tire having a pattern on its surface consisting of a continuous ridge arranged based on a space-filling curve.

2. The tire according to claim 1, wherein the ridges are arranged based on a Peano curve or a Hilbert curve.

3. A tire according to claim 1, wherein the pattern portion has a width of the ridges of 0.03 mm or more and 0.5 mm or less, and the pitch between adjacent ridges is 0.5 mm or less.

4. A tire as set forth in claim 1, wherein the pattern portion is provided on the inner bottom of a recess in a recessed marking portion.

5. A tire as set forth in claim 1, wherein the pattern portion is provided around a convex portion of a protruding marking portion.

6. A tire as set forth in claim 1, wherein the pattern portion is provided by edging the periphery of a convex portion of a protruding marking portion.

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