pneumatic tires

Abstract

To make concavities and convexities of bulges, dents, bears and the like unnoticeable to improve an appearance of a side wall part.SOLUTION: In a pneumatic tire, a concave-convex region 10 is formed in a side wall part 3. The concavo-convex region 10 includes a plurality of reference surface parts 11, a plurality of first convex surface parts 12 and a plurality of first concave surface parts 13. In a front view of the side wall part 3, the first convex surface parts 12 and the first concave surface parts 13 are formed in a quadrilateral shape. Portions of first partition regions K1 between pairs P1 of the first convex surface parts 12 and the first concave surface parts 13 arranged adjacently to each other in a tire circumferential direction are formed of the reference surface parts 11. Portions of second partition regions K2 between pairs P2 of the first convex surface parts 12 and the first concave surface parts 13 arranged adjacently to each other in a tire radial direction are formed of the reference surface parts 11. Intersection parts Kc between the first partition regions K1 and the second partition regions K2 are formed of second surface parts 14.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a pneumatic tire.

Background Art

[0002] Patent Document 1 below describes a pneumatic tire having a serration pattern including a plurality of grooves extending in the tire radial direction on the surface of the sidewall portion and ridges formed between adjacent grooves. The groove depth of the grooves becomes smaller as it goes toward the outer side in the tire radial direction.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] On the outer surface of the sidewall portion of the tire, irregularities such as bulges, dents, and bare spots may be formed. Although these irregularities do not affect the original running performance of the tire, they tend to deteriorate the appearance of the sidewall portion.

[0005] In view of the above situation, the present invention has been devised, and an object thereof is to provide a pneumatic tire capable of improving the appearance of the sidewall portion by making irregularities such as bulges, dents, and bare spots less noticeable.

Means for Solving the Problems

[0006] The present invention relates to a pneumatic tire comprising a tread portion and a pair of sidewall portions extending radially inward from the tread portion, wherein an uneven region is formed on the outer surface of at least one of the pair of sidewall portions, the uneven region comprising a plurality of reference surface portions, a plurality of first convex portions projecting outward in the tire axial direction from the reference surface portions, and a plurality of first concave portions recessed inward in the tire axial direction from the reference surface portions, wherein in a front view of the sidewall portion, the plurality of first convex portions and the plurality of first concave portions are each quadrangular in shape, and the plurality of first convex portions and the plurality of first concave portions alternate in the tire circumferential direction and tire radial direction. The pneumatic tire is formed by repeating arrangements of the first convex and first concave portions, with a first compartmentalized region extending in the tire radial direction between each pair of adjacent first convex and first concave portions in the tire radial direction, a second compartmentalized region extending in the tire radial direction between each pair of adjacent first convex and first concave portions in the tire radial direction, a part of the first compartmentalized region being formed by the reference surface portion, a part of the second compartmentalized region being formed by the reference surface portion, and the intersection between the first compartmentalized region and the second compartmentalized region being formed by a second surface portion having an outer surface at a different position in the tire axial direction from the reference surface portion, the first convex portion, and the first concave portion. [Effects of the Invention]

[0007] By adopting the above configuration, the pneumatic tire of the present invention can reduce the visibility of irregularities such as bulges, dents, and bares, thereby improving the appearance of the sidewall. [Brief explanation of the drawing]

[0008] [Figure 1] A partial side view showing one embodiment of the pneumatic tire of the present invention. [Figure 2] This is an enlarged front view of the sidewall portion of this embodiment. [Figure 3] (A) is a cross-sectional view along line AA in Figure 2, (B) is a cross-sectional view along line CC in Figure 2, and (C) is a cross-sectional view along line EE in Figure 2. [Figure 4]This is an enlarged view of the uneven region in Figure 2. [Figure 5] Figure 2 is a partial perspective view of the uneven region. [Figure 6] (A) is a front view of the uneven region of another embodiment, and (B) is a cross-sectional view of (A). [Figure 7] This is a partial side view of a pneumatic tire according to an embodiment. [Figure 8] (A) is a front view of the uneven region of yet another embodiment, and (B) is a cross-sectional view of (A) at HH. [Figure 9] This is a front view of the uneven region of yet another embodiment. [Figure 10] This is a front view of the uneven region of yet another embodiment. [Modes for carrying out the invention]

[0009] One embodiment of the present invention will be described below with reference to the drawings. Figure 1 is a partial side view showing one embodiment of the pneumatic tire (hereinafter sometimes simply referred to as "tire") 1 of the present invention. Figure 1 shows a pneumatic tire 1 for a passenger car as a preferred embodiment. However, the present invention may also be used, for example, for motorcycles or heavy-duty tires 1.

[0010] In this specification, unless otherwise specified, the dimensions of each part of tire 1 are measured under normal conditions. "Normal conditions" means that tire 1 is mounted on a normal rim (not shown), filled with normal internal pressure, and under no load.

[0011] A "standard rim" is the rim defined for each tire within the standards system that the tire is based on. For example, it is the "standard rim" for JATMA, the "Design Rim" for TRA, and the "Measuring Rim" for ETRTO.

[0012] "Regular internal pressure" refers to the air pressure specified for each tire by each standard within the tire standard system, including the standard on which the tire is based. For JATMA, it is the "maximum air pressure," for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, it is the "INFLATION PRESSURE."

[0013] The tire 1 of this embodiment includes a tread portion 2 and a pair of sidewall portions 3 extending radially inward from the tread portion 2. Figure 1 shows one of the sidewall portions 3.

[0014] An uneven region 10 is formed on at least one outer surface 3a of a pair of sidewall portions 3. The uneven region 10 is formed on both of the pair of sidewall portions 3, for example. In this embodiment, the uneven region 10 is formed to be interrupted in the tire circumferential direction. The uneven region 10 may also be formed to be continuous in the tire circumferential direction, for example. The uneven region 10 is also formed to extend inward and outward in the tire radial direction, for example, straddling the tire maximum width position M. The uneven region 10 includes an outer portion 10A located radially outward from the tire maximum width position M, and an inner portion 10B located radially inward of the outer portion 10A. It is desirable that the tire radial length LB of the inner portion 10B is smaller than the tire radial length LA of the outer portion 10A. It is desirable that the uneven region 10 is located in the range of 20% to 100% of the tire radial length Lp between the tread edge Te and the bead baseline BL, for example. Such positions are easily visible. The bead baseline BL is the line that defines the rim diameter of the standard rim (see JATMA, etc.).

[0015] Figure 2 is an enlarged view of the concavo-convex region 10 of the sidewall portion 3 in FIG. 1 as seen from the front. FIG. 3(A) is a cross-sectional view taken along line A-A in FIG. 2, FIG. 3(B) is a cross-sectional view taken along line C-C in FIG. 2, and FIG. 3(C) is a cross-sectional view taken along line E-E in FIG. 2. In the present embodiment, the cross-sectional shape along line A-A in FIG. 2 is the same as the cross-sectional shape along line B-B in FIG. 2, the cross-sectional shape along line C-C in FIG. 2 is the same as the cross-sectional shape along line D-D in FIG. 2, and the cross-sectional shape along line E-E in FIG. 2 is the same as the cross-sectional shape along line F-F in FIG. 2. As shown in FIGS. 2 and 3, the concavo-convex region 10 includes a plurality of reference surface portions 11, a plurality of first convex surface portions 12 that protrude outward in the tire axial direction from the reference surface portions 11, and a plurality of first concave surface portions 13 that are recessed inward in the tire axial direction from the reference surface portions 11. In FIG. 2, the tire radial direction is indicated by the direction of the arrow with the symbol r (in the figure, the vertical direction), and the tire circumferential direction is indicated by the direction of the arrow with the symbol f (in the figure, the horizontal direction). Note that the tire radial direction extends radially around the tire rotation axis (not shown), but in FIG. 2, for the sake of convenience, it is shown as being parallel to the vertical direction in the figure. Also, the tire circumferential direction extends in an arc shape, but in FIG. 2, for the sake of convenience, it is shown as being linear.

[0016] The reference surface portion 11 has an outer surface 11a facing outward in the tire axial direction. The first convex surface portion 12 has an outer surface 12a facing outward in the tire axial direction. The first concave surface portion 13 has an outer surface 13a facing outward in the tire axial direction. Each of the first convex surface portion 12 and the first concave surface portion 13 further has an axial surface 20 that extends in the tire axial direction and is connected to each of the outer surfaces 12a, 13a.

[0017] A first partition region K1 that extends in the tire radial direction is formed between each pair P1 of the first convex surface portion 12 and the first concave surface portion 13 adjacent to each other in the tire circumferential direction. Also, a second partition region K2 that extends in the tire circumferential direction is formed between each pair P2 of the first convex surface portion 12 and the first concave surface portion 13 adjacent to each other in the tire radial direction.

[0018] Furthermore, a portion of the first sectioned area K1 is formed by the reference surface portion 11. Also, a portion of the second sectioned area K2 is formed by the reference surface portion 11. In addition, the intersection Kc between the first sectioned area K1 and the second sectioned area K2 is formed by the second surface portion 14. The second surface portion 14 has an outer surface 14a at a different position in the tire axis direction from the reference surface portion 11, the first convex surface portion 12, and the first concave surface portion 13. Thus, the uneven area 10 has outer surfaces 11a, 12a, 13a, and 14a formed at at least four different positions in the tire axis direction, resulting in at least four levels of brightness. In other words, the uneven area 10 has a reference surface portion 11 and at least three surface portions that have different protrusion heights or depths from the reference surface portion 11, resulting in at least four levels of brightness. The second surface portion 14 further has, for example, an axial surface 20 that extends in the tire axis direction, connected to the outer surface 14a.

[0019] Furthermore, in a front view of the sidewall portion 3, the multiple first convex portions 12 and the multiple first concave portions 13 are each quadrilateral in shape. The "quadrilateral shape" is defined by the shape of the outer surface 12a of the first convex portion 12 (four edges e intersecting the outer surface 12a and the axial surface 20), or the shape of the outer surface 13a of the first concave portion 13 (four edges e intersecting the outer surface 13a and the axial surface 20). In a front view of the sidewall portion 3, the edges e include not only those that extend in a straight line, but also those that extend in an arc shape (curve) with a large radius of curvature due to precision errors in tire manufacturing. It also includes those in which edges e are connected in an arc shape with a small radius of curvature.

[0020] Furthermore, the multiple first convex portions 12 and the multiple first concave portions 13 are arranged alternately in the tire circumferential direction and the tire radial direction. As a result, in a front view of the sidewall portion 3, the multiple first convex portions 12 and the multiple first concave portions 13 form, for example, a grid pattern. Therefore, the uneven region 10 causes, for example, a café wall illusion, making bulges, dents, bares, etc., formed in the uneven region 10 less noticeable, thereby improving the appearance performance of the sidewall portion 3 (hereinafter simply referred to as "appearance performance"). In this specification, the effect of making bulges, dents, bares, etc., less noticeable may be referred to as the "anti-concealment effect".

[0021] The reference surface portion 11 (outer surface 11a) coincides with a surface 3A that extends smoothly from the outer surface 3a of the sidewall portion 3, which determines the tire section width (see JATMA), in the tire meridian cross-section (not shown).

[0022] In a front view of the sidewall portion 3, the multiple reference surface portions 11 are formed in a quadrilateral shape, or in this embodiment, a rectangular shape. The term "rectangular shape" includes not only the case where the outer surface 11a is rectangular, but also the case where, due to precision errors in tire manufacturing, the outer edge of the outer surface 11a extends in an arc shape (curve) with a large radius of curvature, or the case where the bent portion of the outer edge is formed in an arc shape with a small radius of curvature.

[0023] In a front view of the sidewall portion 3, the multiple first convex portions 12 and the multiple first concave portions 13 are each formed in a square shape. As a result, the multiple first convex portions 12 and the multiple first concave portions 13 form, for example, a square grid. Therefore, the uneven area 10 further induces the café wall illusion, enhancing the non-contrasting effect and improving the appearance performance. The "square shape" refers to a configuration in which the outer surfaces 12a and 13a (four edges e) are square, as well as configurations in which the edges e extend in an arc shape with a large radius of curvature due to precision errors in tire manufacturing, or configurations in which the edges e are connected in an arc shape with a small radius of curvature.

[0024] Figure 4 is an enlarged view of the uneven region 10 in Figure 2. Figure 5 is a partial perspective view of the uneven region 10. As shown in Figure 4 or Figure 5, the outer surfaces 12a of the first convex portion 12 and 13a of the first concave portion 13, which are aligned in the circumferential direction of the tire, are formed, for example, with the same shape. The outer surfaces 12a of the first convex portion 12 and 13a of the first concave portion 13, which are aligned in the circumferential direction of the tire, are formed, for example, with the same area. The lengths h1 and h2 of the first convex portion 12 and the first concave portion 13, which are aligned in the circumferential direction of the tire, are the same in the radial direction of the tire. The first convex portion 12 and the first concave portion 13, which are aligned in the circumferential direction of the tire, are formed at the same position in the radial direction of the tire without any displacement in that direction. This further induces the café wall illusion.

[0025] From a similar viewpoint, it is desirable that the outer surfaces 12a of the first convex portion 12 and 13a of the first concave portion 13, which are aligned in the radial direction of the tire, are formed with the same shape. For example, the outer surfaces 12a of the first convex portion 12 and 13a of the first concave portion 13, which are aligned in the radial direction of the tire, are formed with the same area. The lengths t1 and t2 of the first convex portion 12 and the first concave portion 13, which are aligned in the radial direction of the tire, are the same. It is desirable that the first convex portion 12 and the first concave portion 13, which are aligned in the radial direction of the tire, are formed at the same position in the circumferential direction of the tire without any displacement in that direction. In the sidewall portion 3, the circumference centered on the tire rotation axis (not shown) becomes larger towards the outside in the radial direction of the tire. Therefore, the lengths t1 and t2 in the tire circumferential direction of the outer surfaces 12a of the first convex portion 12 and 13a of the first concave portion 13, which are aligned in the tire radial direction, may be larger than the outer surfaces 12a and 13a located on the outside in the tire radial direction.

[0026] The length h1 of the first convex portion 12 in the tire radial direction and the length h2 of the first concave portion 13 in the tire radial direction are preferably, for example, 2.0 mm or more, more preferably 3.0 mm or more, preferably 15.0 mm or less, and even more preferably 10.0 mm or less. The length t1 of the first convex portion 12 in the tire circumferential direction and the length t2 of the first concave portion 13 in the tire circumferential direction are preferably, for example, 2.0 mm or more, more preferably 3.0 mm or more, preferably 15.0 mm or less, and even more preferably 10.0 mm or less.

[0027] In the uneven region 10, multiple first section regions K1 are provided in the tire circumferential direction. Multiple second section regions K2 are provided in the tire radial direction. As a result, the intersections Kc are aligned in both the tire circumferential and tire radial directions. Also, the second surface portion 14 is aligned in both the tire circumferential and tire radial directions.

[0028] In this embodiment, the first compartmentalized region K1 extends longitudinally through the uneven region 10 in the tire radial direction. In this embodiment, the second compartmentalized region K2 extends transversely through the uneven region 10 in the tire circumferential direction. The first compartmentalized region K1 is formed such that, for example, its length t3 in the tire circumferential direction is the same both inside and outside the tire radial direction. However, the length t3 in the tire circumferential direction of the first compartmentalized region K1 may continuously decrease toward the inside of the tire radial direction (not shown). The second compartmentalized region K2 is formed such that, for example, its length h3 in the tire radial direction is the same along the tire circumferential direction.

[0029] The length t3 of the first compartment region K1 in the tire circumferential direction is preferably 5% or more of the length t1 of the first convex portion 12 in the tire circumferential direction, more preferably 10% or more, preferably 30% or less, and more preferably 25% or less. Since the length t3 of the first compartment region K1 in the tire circumferential direction is 5% or more of the length t1 of the first convex portion 12 in the tire circumferential direction, the brightness due to the reference surface portion 11 and the second surface portion 14 becomes easier to recognize. Since the length t3 of the first compartment region K1 in the tire circumferential direction is 30% or less of the length t1 of the first convex portion 12 in the tire circumferential direction, the inclination of the grid frame due to the café wall illusion is maintained, and the non-contrasting effect is exerted. In order to effectively exert the above effects, the length h3 of the second compartment region K2 in the tire radial direction is preferably 5% or more of the length h1 of the first convex portion 12 in the tire radial direction, more preferably 10% or more, preferably 30% or less, and more preferably 25% or less.

[0030] The second surface portion 14 includes a second convex portion 15 that protrudes outward in the tire axial direction from the first convex portion 12. The second surface portion 14 also includes a second concave portion 16 that is recessed inward in the tire axial direction from the first concave portion 13. The second convex portion 15 and the second concave portion 16 each include outer surfaces 15a and 16a facing outward in the tire axial direction, and axial surfaces 20 that extend in the tire axial direction and are connected to the outer surfaces 15a and 16a, respectively. As a result, the uneven region 10 of this embodiment has outer surfaces 11a to 13a, 15a, and 16a formed at five different positions in the tire axial direction, thus creating at least five levels of brightness. Note that the second surface portion 14 may be formed by only either the second convex portion 15 or the second concave portion 16. In this embodiment, the second convex portion 15, the first convex portion 12, the reference surface portion 11, the first concave portion 13, and the second concave portion 16 are arranged in order of decreasing brightness. In Figures 2 and 4, for convenience, the outer surfaces 11a to 13a, 15a, and 16a are shown in lighter colors in order of decreasing brightness.

[0031] In a front view of the sidewall portion 3, the second surface portion 14 in this embodiment is formed in a cross shape extending from the intersection Kc in the tire radial direction and the tire circumferential direction. This ensures a large area of ​​the second surface portion 14, making the second convex portion 15, which is a particularly bright area, and the second concave portion 16, which is a particularly dark area, clearer, thereby enhancing the café wall illusion and improving the appearance performance. The second surface portion 14 is not limited to being formed in a cross shape; for example, in a front view of the sidewall portion 3, it may be circular, elliptical, or polygonal. The term "cross shape" is specified in the same way as the term "rectangular shape."

[0032] In this embodiment, the uneven region 10 has a second convex portion 15 and a second concave portion 16 formed alternately in the tire circumferential direction and the tire radial direction. This makes the contrast between light and dark in the uneven region 10 clearer, resulting in a more effective café wall illusion.

[0033] As shown in Figures 2 and 3(A) to 3(C), the uneven region 10 of this embodiment includes a first portion 21, a second portion 22, and a third portion 23. In the first portion 21 of this embodiment, the first concave portion 13, the reference surface portion 11, the first convex portion 12, and the reference surface portion 11 are repeated in the tire radial direction and the tire circumferential direction. In the second portion 22 of this embodiment, the first convex portion 12, the second convex portion 15, the first concave portion 13, and the second concave portion 16 are repeated in the tire radial direction and the tire circumferential direction. In the third portion 23 of this embodiment, the reference surface portion 11, the second concave portion 16, the reference surface portion 11, and the second convex portion 15 are repeated in the tire radial direction and the tire circumferential direction.

[0034] The outer surface 12a of the first convex portion 12 preferably protrudes 0.2 mm or more outward in the tire axial direction relative to the outer surface 11a of the reference surface portion 11, more preferably 0.3 mm or more, more preferably 0.6 mm or less, and more preferably 0.5 mm or less. The outer surface 13a of the first concave portion 13 preferably recesses 0.2 mm or more inward in the tire axial direction relative to the outer surface 11a of the reference surface portion 11, more preferably 0.3 mm or more, more preferably 0.6 mm or less, and more preferably 0.5 mm or less. Furthermore, the outer surface 15a of the second convex portion 15 preferably protrudes 0.4 mm or more outward in the tire axial direction relative to the outer surface 11a of the reference surface portion 11, more preferably 0.6 mm or more, more preferably 1.0 mm or less, and more preferably 0.8 mm or less. Furthermore, the outer surface 16a of the second concave portion 16 is preferably recessed 0.4 mm or more inward in the tire axial direction relative to the outer surface 11a of the reference surface portion 11, more preferably 0.6 mm or more, preferably 1.0 mm or less, and most preferably 0.8 mm or less. This enhances the contrast in brightness between the reference surface portion 11, the first convex portion 12, the first concave portion 13, the second convex portion 15, and the second concave portion 16, thereby further improving the appearance performance. Also, if the outer surface 12a of the first convex portion 12 and the outer surface 15a of the second convex portion 15 are located excessively outward in the tire axial direction, the amount of work required to cut the mold (not shown) for manufacturing the tire 1 will increase, which may worsen the mold machinability. If the outer surface 13a of the first concave portion 13 and the outer surface 16a of the second concave portion 16 are located excessively inward in the tire axial direction, the amount of work required to excavate the tire 1 will increase, which may worsen the tire's workability.

[0035] In order to effectively exert the above-mentioned effects, it is desirable that the outer surface 15a of the second convex portion 15 protrudes 0.2 mm or more outward in the tire axial direction relative to the outer surface 12a of the first convex portion 12, and more preferably protrudes 0.3 mm or more. It is desirable that the outer surface 16a of the second concave portion 16 is recessed 0.2 mm or more inward in the tire axial direction relative to the outer surface 13a of the first concave portion 13, and more preferably recessed 0.3 mm or more.

[0036] It is desirable that the area A4 of one of the second convex portions 15 and the area A5 of one of the second concave portions 16 are smaller than the respective areas A2 of the multiple first convex portions 12 and the respective areas A3 of the multiple first concave portions 13. It is also desirable that the area A4 of one of the second convex portions 15 and the area A5 of one of the second concave portions 16 are larger than the respective areas A1 of the multiple reference surfaces 11. The second convex portions 15 are the parts with the highest brightness. The second concave portions 16 are the parts with the lowest brightness. Therefore, by making the area A4 of the second convex portions 15 and the area A5 of the second concave portions 16 larger than the area A1 of the reference surfaces 11, the contrast of the uneven region 10 can be increased. Furthermore, because the area A4 of the second convex portion 15 and the area A5 of the second concave portion 16 are smaller than the area A2 of the first convex portion 12 and the area A3 of the first concave portion 13, the grid-like appearance effect created by the first convex portion 12 and the first concave portion 13 is maintained to a high degree. As a result, the café wall illusion is effectively manifested, and the effect of making it less noticeable is ensured to a high degree.

[0037] Each area A1 to A5 is the area at the same height position in the tire axial direction as the reference surface 11. The area of ​​the axial surface 20 is not included in each area A1 to A5. Figure 5 illustrates the area A1 of the reference surface 11, the area A2 of the first convex surface 12, and the area A3 of the first concave surface 13.

[0038] As shown in Figure 4, it is desirable that the length t4 of the reference surface portion 11 formed in the second partitioned region K2 in the tire circumferential direction is smaller than the lengths t1 and t2 of the adjacent first convex portion 12 and first concave portion 13 in the tire circumferential direction. This makes the grid pattern formed by the first convex portion 12 and first concave portion 13 more prominent, and thus a greater café wall illusion effect can be expected. From a similar viewpoint, it is desirable that the length h4 of the reference surface portion 11 formed in the first partitioned region K1 in the tire circumferential direction is smaller than the lengths h1 and h2 of the adjacent first convex portion 12 and first concave portion 13 in the tire circumferential direction.

[0039] While not particularly limited, the length t4 of the reference surface portion 11 formed in the second compartment region K2 in the tire circumferential direction is preferably 1.5 mm or more, more preferably 2.0 mm or more, preferably 8.0 mm or less, and even more preferably 7.5 mm or less. The length h4 of the reference surface portion 11 formed in the first compartment region K1 in the tire radial direction is preferably 1.5 mm or more, more preferably 2.0 mm or more, preferably 8.0 mm or less, and even more preferably 7.5 mm or less.

[0040] Figure 6(A) is an enlarged front view of the uneven region 10 of another embodiment, and Figure 6(B) is a cross-sectional view of the GG line in Figure 6(A). Components identical to those in this embodiment may be denoted by the same reference numerals and their descriptions may be omitted. As shown in Figure 6, at least one outer surface 13a, 16a of at least one of the multiple first concave portions 13 or multiple second concave portions 16 has a plurality of micro-protrusions 25 that rise from each outer surface. In this embodiment, the micro-protrusions 25 are provided on the outer surface 13a of the first concave portion 13 and the outer surface 16a of the second concave portion 16, respectively. The micro-protrusions 25 further reduce the brightness of the first concave portion 13 and the second concave portion 16, increasing the contrast with the first convex portion 12 and the second convex portion 15, thereby improving the inconspicuous effect.

[0041] It is desirable that the protruding ends 25e of the multiple micro-protrusions 25 in the tire axial direction be located inward in the tire axial direction from the reference surface portion 11 (outer surface 11a). If the protruding ends 25e are located outward in the tire axial direction from the reference surface portion 11, the light irradiated onto the protruding ends 25e of the micro-protrusions 25 may be reflected, increasing the brightness of the first concave portion 13 or the second concave portion 16, reducing the contrast of the uneven region 10, and potentially diminishing the effect of the café wall illusion. Although not particularly limited, it is desirable that the protruding ends 25e of the micro-protrusions 25 of the first concave portion 13 be recessed by 0.1 mm or more than the reference surface portion 11, and more preferably by 0.2 mm or more. It is desirable that the protruding ends 25e of the micro-protrusions 25 of the second concave portion 16 be recessed by 0.1 mm or more than the outer surface 13a of the first concave portion 13, and more preferably by 0.2 mm or more.

[0042] As shown in Figure 6, the minute protrusions 25 in this embodiment are formed as linear protrusions 26 that extend linearly on the outer surfaces 13a and 16a. The linear protrusions 26 are provided, for example, at the same pitch. The linear protrusions 26 may extend to the edges of the outer surfaces 13a and 16a at both ends in the longitudinal direction, or they may be interrupted on the outer surfaces 13a and 16a without extending to the edges of the outer surfaces 13a and 16a.

[0043] The longitudinal direction of the linear projection 26 is not particularly limited and can extend in any direction: in the circumferential direction of the tire, the radial direction of the tire, or inclined with respect to the radial direction of the tire. Figure 7 is a partial side view and an enlarged view thereof of the tire 1 of this embodiment. As shown in Figure 7, it is desirable that the longitudinal direction of all linear projections 26 be aligned in the same direction with respect to the tire radial line n passing through the tire rotation axis (not shown). In this embodiment, the direction of light reflection becomes the same, and the difference in brightness within the first concave portion 13 can be eliminated (reduced). The linear projection 26 shown in Figure 7 extends in a direction perpendicular to the tire radial line n, for example.

[0044] Figure 8(A) is an enlarged front view of the uneven region 10 of yet another embodiment, and Figure 8(B) is a cross-sectional view of Figure 8(A) along line HH. Components identical to those in this embodiment may be given the same reference numerals and their descriptions may be omitted. As shown in Figure 8, a plurality of minute protrusions 25 are provided on the outer surface 13a of the first concave portion 13. In this embodiment, the minute protrusions 25 are configured as conical protrusions 27 that are convex outward in the tire axial direction.

[0045] Multiple conical protrusions 27 are, for example, composed of the same size and shape. In this embodiment, the top portion 27a of the conical protrusions 27 is rounded. Compared to the linear protrusions 26, the conical protrusions 27 have a larger total surface area per first concave portion 13, so they absorb more irradiated light, making the first concave portion 13 appear darker and enhancing the inconspicuous effect.

[0046] The diameter D1 of the conical projection 27 is, for example, 0.2 to 0.6 mm, preferably 0.3 to 0.5 mm. Note that diameter D1 refers to the diameter of the base portion of the conical projection 27. 1 mm of the outer surface 13a 2 The average number of conical protrusions 27 per surface is, for example, 2 to 8. However, the shape of the conical protrusions 27 is not limited to this configuration.

[0047] Figure 8(C) is an enlarged cross-sectional view of the conical projection 27 of another embodiment. As shown in Figure 8(C), in this embodiment, a minute recess 27b is formed at the top 27a of the conical projection 27. The conical projection 27 having such a recess 27b can disperse and reflect light in various directions, increasing the blackness of the first concave portion 13 and lowering its brightness. The conical projection 27 may be provided, for example, on the outer surface 16a of the second concave portion 16. The shape of the minute projection 25 is not limited to the linear projection 26 or the conical projection 27, but can be formed in various shapes.

[0048] Figure 9 is a front view of the uneven region 10 in yet another embodiment. Figure 9 is a front view of the sidewall portion 3. Components identical to those in this embodiment may be given the same reference numerals and their descriptions may be omitted. As shown in Figure 9, in this embodiment, a plurality of first compartmentalized regions K1 are arranged inclined with respect to the tire circumferential direction, and a plurality of second compartmentalized regions K2 are arranged inclined in the opposite direction to the first compartmentalized regions K1. In this embodiment, the first convex portion 12 and the first concave portion 13 are formed in a rhomboid shape. Even in the uneven region 10 of this embodiment, the anti-contact effect is achieved and the appearance performance is improved.

[0049] Figure 10 is a front view of the uneven region 10 of yet another embodiment. Figure 10 is a front view of the sidewall portion 3. Components identical to those in this embodiment may be given the same reference numerals and their descriptions may be omitted. As shown in Figure 10, in this embodiment, a plurality of first partitioned regions K1 are arranged inclined with respect to the tire circumferential direction, and a plurality of second partitioned regions K2 are arranged to extend in the tire circumferential direction. In this embodiment, the first convex portion 12 and the first concave portion 13 are formed in a parallelogram shape including a rhombic shape. Even in the uneven region 10 of such embodiments, the anti-contact effect is achieved and the appearance performance is improved.

[0050] Although particularly preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the illustrated embodiments and can be implemented in various modified forms.

[0051] [Note] The present invention includes the following embodiments.

[0052] [Invention 1] It is a pneumatic tire, It includes a tread portion and a pair of sidewall portions extending radially inward from the tread portion, An uneven region is formed on the outer surface of at least one of the pair of sidewall portions. The aforementioned uneven region includes a plurality of reference surface portions, a plurality of first convex surface portions that protrude outward in the tire axial direction from the reference surface portions, and a plurality of first concave surface portions that are recessed inward in the tire axial direction from the reference surface portions. In a front view of the sidewall portion, the plurality of first convex portions and the plurality of first concave portions are each quadrilateral in shape. The plurality of first convex portions and the plurality of first concave portions are arranged alternately in the tire circumferential direction and the tire radial direction. Between each pair of adjacent first convex and first concave portions in the circumferential direction of the tire, a first partitioned region extending in the radial direction of the tire is formed. Between each pair of the first convex and first concave portions adjacent in the tire radial direction, a second partitioned region extending in the tire circumferential direction is formed. A portion of the first partitioned area is formed by the reference surface portion, A portion of the second partitioned area is formed by the reference surface portion, The intersection between the first partitioned area and the second partitioned area is formed by a second surface having an outer surface at a different position in the tire axial direction from the reference surface, the first convex surface, and the first concave surface. Pneumatic tires. [Invention 2] The pneumatic tire according to the present invention 1, wherein the second surface portion includes a second convex portion that protrudes outward in the tire axial direction from the first convex portion. [Invention 3] The pneumatic tire according to invention 1 or 2, wherein the second surface portion includes a second concave portion that is recessed inward in the tire axial direction compared to the first concave portion. [4th Invention] The pneumatic tire according to the present invention 1, wherein the second surface portion includes a second convex portion that protrudes outward in the tire axial direction from the first convex portion and a second concave portion that is recessed inward in the tire axial direction from the first concave portion, and these are formed alternately in the tire circumferential direction and the tire radial direction. [5th ​​Invention] In a front view of the sidewall portion, the second surface portion is formed in a cross shape extending from the intersection in the tire radial direction and the tire circumferential direction, as described in invention 1 or 2. [Invention 6] The outer surface of the first convex portion protrudes 0.2 to 0.6 mm outward in the tire axial direction relative to the outer surface of the reference surface portion. The outer surface of the first concave portion is recessed 0.2 to 0.6 mm inward in the tire axial direction relative to the outer surface of the reference surface portion. The outer surface of the second convex portion protrudes 0.4 to 1.0 mm outward in the tire axial direction relative to the outer surface of the reference surface portion. The pneumatic tire according to the present invention, wherein the outer surface of the second concave portion is recessed 0.4 to 1.0 mm inward in the tire axial direction relative to the outer surface of the reference surface portion. [7th Invention] The outer surface of the second convex portion protrudes 0.2 mm or more outward in the tire axial direction relative to the outer surface of the first convex portion. The pneumatic tire according to claim 4 or 6 of the present invention, wherein the outer surface of the second concave portion is recessed by 0.2 mm or more inward in the tire axial direction relative to the outer surface of the first concave portion. [8th Invention] The pneumatic tire according to invention 1 or 2, wherein the length of the first compartment region in the tire circumferential direction is 30% or less of the length of the first convex portion in the tire circumferential direction. [Invention 9] The pneumatic tire according to invention 1 or 2, wherein the length of the second compartment region in the tire radial direction is 30% or less of the length of the first convex portion in the tire radial direction. [Invention 10] A pneumatic tire according to the present invention, wherein a plurality of micro-protrusions are formed on at least one of the outer surfaces of at least one of the plurality of first concave portions or the plurality of second concave portions. [Invention 11] The pneumatic tire according to the present invention 10, wherein the protruding ends of the plurality of minute protrusions in the tire axial direction are located inward in the tire axial direction from the reference surface portion. [Invention 12] The pneumatic tire according to the present invention, wherein the area of ​​one of the second convex portions and the area of ​​one of the second concave portions are smaller than the respective areas of the plurality of first convex portions and the respective areas of the plurality of first concave portions, and larger than the respective areas of the plurality of reference surfaces. [Invention 13] In a front view of the sidewall portion, the plurality of first convex portions and the plurality of first concave portions are each formed in a square shape, as described in invention 1 or 2 of the present invention. [Invention 14] The pneumatic tire according to invention 1 or 2, wherein the length of the reference surface portion formed in the second partitioned region in the tire circumferential direction is smaller than the length of the first convex portion and the first concave portion adjacent to each other in the tire radial direction. [Invention 15] The pneumatic tire according to invention 1 or 2, wherein the length of the reference surface portion formed in the first partitioned region in the tire radial direction is smaller than the length of the adjacent first convex portion and first concave portion in the tire radial direction in the tire circumferential direction. [Explanation of symbols]

[0053] 1. Pneumatic tire 3. Sidewall section 10 Uneven area 11 Reference plane section 12 First convex part 13 First concave part 14 Second surface section K1 First Section Area K2 Second Section Area Kc intersection P1 Pair P2 pair

Claims

1. It is a pneumatic tire, It includes a tread portion and a pair of sidewall portions extending radially inward from the tread portion, An uneven region is formed on the outer surface of at least one of the pair of sidewall portions. The uneven region includes a plurality of reference surface portions, a plurality of first convex surface portions that protrude outward in the tire axial direction from the reference surface portions, and a plurality of first concave surface portions that are recessed inward in the tire axial direction from the reference surface portions. In a front view of the sidewall portion, the plurality of first convex portions and the plurality of first concave portions are each quadrilateral in shape. The plurality of first convex portions and the plurality of first concave portions are arranged alternately in the tire circumferential direction and the tire radial direction. Between each pair of adjacent first convex and first concave portions in the circumferential direction of the tire, a first partitioned region extending in the radial direction of the tire is formed. Between each pair of the first convex and first concave portions adjacent in the tire radial direction, a second partitioned region extending in the tire circumferential direction is formed. A portion of the first partitioned area is formed by the reference surface portion, A portion of the second partitioned area is formed by the reference surface portion, The intersection between the first partitioned area and the second partitioned area is formed by a second surface having an outer surface at a different position in the tire axial direction from the reference surface, the first convex surface, and the first concave surface. Pneumatic tires.

2. The pneumatic tire according to claim 1, wherein the second surface portion includes a second convex portion that protrudes outward in the tire axial direction from the first convex portion.

3. The pneumatic tire according to claim 1 or 2, wherein the second surface portion includes a second concave portion that is recessed inward in the tire axial direction compared to the first concave portion.

4. The pneumatic tire according to claim 1, wherein the second surface portion includes a second convex portion that protrudes outward in the tire axial direction from the first convex portion and a second concave portion that is recessed inward in the tire axial direction from the first concave portion, and these are formed alternately in the tire circumferential direction and the tire radial direction.

5. In a front view of the sidewall portion, the second surface portion is formed in a cross shape extending from the intersection portion in the tire radial direction and the tire circumferential direction, as described in claim 1 or 2.

6. The outer surface of the first convex portion protrudes 0.2 to 0.6 mm outward in the tire axial direction relative to the outer surface of the reference surface portion. The outer surface of the first concave portion is recessed 0.2 to 0.6 mm inward in the tire axial direction relative to the outer surface of the reference surface portion. The outer surface of the second convex portion protrudes 0.4 to 1.0 mm outward in the tire axial direction relative to the outer surface of the reference surface portion. The pneumatic tire according to claim 4, wherein the outer surface of the second concave portion is recessed 0.4 to 1.0 mm inward in the tire axial direction relative to the outer surface of the reference surface portion.

7. The outer surface of the second convex portion protrudes 0.2 mm or more outward in the tire axial direction relative to the outer surface of the first convex portion. The pneumatic tire according to claim 4 or 6, wherein the outer surface of the second concave portion is recessed by 0.2 mm or more inward in the tire axial direction relative to the outer surface of the first concave portion.

8. The pneumatic tire according to claim 1 or 2, wherein the length of the first compartment region in the tire circumferential direction is 30% or less of the length of the first convex portion in the tire circumferential direction.

9. The pneumatic tire according to claim 1 or 2, wherein the length of the second compartment region in the tire radial direction is 30% or less of the length of the first convex portion in the tire radial direction.

10. The pneumatic tire according to claim 4, wherein a plurality of micro-protrusions are formed on at least one of the outer surfaces of at least one of the first concave portion or the second concave portion.

11. The pneumatic tire according to claim 10, wherein the protruding ends of the plurality of minute protrusions in the tire axial direction are located inward in the tire axial direction from the reference surface portion.

12. The pneumatic tire according to claim 4, wherein the area of ​​one of the second convex portions and the area of ​​one of the second concave portions are smaller than the respective areas of the plurality of first convex portions and the respective areas of the plurality of first concave portions, and larger than the respective areas of the plurality of reference surfaces.

13. In a front view of the sidewall portion, the plurality of first convex portions and the plurality of first concave portions are each formed in a square shape, as described in claim 1 or 2.

14. The pneumatic tire according to claim 1 or 2, wherein the length of the reference surface portion formed in the second partitioned region in the tire circumferential direction is smaller than the length of the first convex portion and the first concave portion adjacent to each other in the tire radial direction.

15. The pneumatic tire according to claim 1 or 2, wherein the length of the reference surface portion formed in the first partitioned region in the tire radial direction is smaller than the length of the adjacent first convex portion and first concave portion in the tire radial direction in the tire circumferential direction.

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