tire

Abstract

To provide a tire which can exhibit excellent visibility in a concave mark of a side wall part.SOLUTION: A tire includes a pair of side wall parts 3. An outer surface 3s of at least one of the pair of side wall parts 3 includes at least one concave mark 5 recessed from a reference surface. The concave mark 5 includes a bottom surface 6, and an inner wall surface 7. The bottom surface 6 includes a peripheral edge region 10, and a main region 9. The peripheral edge region 10 includes a shadow region 11, and a non-shadow region 12. The shadow region 11 and the non-shadow region 12 are formed of uneven surfaces 15 where a plurality of minute projections 20 are arranged. A width W2 measured in a direction perpendicular to a contour 5o of the uneven surface 15 of the non-shadow region 12 is smaller than a width W1 measured in a direction perpendicular to the contour 5o of the uneven surface 15 of the shadow region 11.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to tires. [Background technology]

[0002] Patent Document 1 below proposes a tire with a recessed mark on the sidewall. In this tire, the bottom surface of the recessed mark includes a shadow area where the wall of the recessed mark is a shadow, and the shadow area has a plurality of minute protrusions. These minute protrusions add contrast to the bottom surface of the recessed mark, thereby improving the visibility of the recessed mark. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-125045 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for further improvement in the visibility of recessed marks on the sidewalls of tires. In particular, the recessed mark in Patent Document 1 sometimes had difficulty in visually recognizing its entire outline depending on the direction of light (viewing direction).

[0005] The present disclosure has been devised in view of the above-described circumstances, and has as its main object to provide a tire that can exhibit excellent visibility of recessed marks on the sidewall portion. [Means for solving the problem]

[0006] The present disclosure relates to a tire including a pair of sidewall portions, wherein the outer surface of at least one of the pair of sidewall portions includes at least one concave mark recessed from a reference plane, the concave mark including a bottom surface and an inner wall surface extending in a depth direction of the concave mark around the bottom surface, the bottom surface including a peripheral region extending along the outline of the concave mark and a main region surrounded by the peripheral region, the peripheral region including a shadow region where a shadow of the inner wall surface is formed when light is irradiated on the concave mark from a first direction, and a non-shadow region where a shadow of the inner wall surface is not formed, the shadow region and the non-shadow region being formed by an uneven surface on which a plurality of minute protrusions are arranged, and a width W2 of the non-shadow region measured in a direction perpendicular to the outline of the uneven surface of the non-shadow region is smaller than a width W1 of the shadow region measured in a direction perpendicular to the outline of the uneven surface of the shadow region. [Effects of the Invention]

[0007] By adopting the above-described configuration, the tire of the present disclosure can exhibit excellent visibility of the recessed mark on the sidewall portion. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is an enlarged perspective view of a sidewall portion of the tire according to the present embodiment. [Figure 2] FIG. 2 is an enlarged plan view of the recessed mark in FIG. 1. [Figure 3] FIG. 3 is an end view taken along line AA in FIG. 2. [Figure 4] FIG. 3 is an enlarged perspective view of an area B in FIG. 2. [Figure 5] FIG. 2 is an enlarged cross-sectional view of the microprotrusions of the present embodiment. [Figure 6] FIG. 10 is an enlarged cross-sectional view of another embodiment of the microprojection. [Figure 7] FIG. 3 is an enlarged plan view of an area B in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present disclosure will now be described with reference to the drawings. FIG. 1 is an enlarged perspective view of a sidewall portion 3 of an embodiment of a tire 1 of the present disclosure. The tire 1 of the present disclosure has a pair of sidewall portions 3, and FIG. 1 shows a portion of the outer surface of one of the sidewall portions 3. As shown in FIG. 1, the tire 1 of the present disclosure is used, for example, as a pneumatic tire for passenger cars. The present disclosure may also be applied, for example, to tires for motorcycles and heavy loads.

[0010] As shown in FIG. 1, the sidewall portion 3 has a visible outer surface 3s. The visible outer surface 3s is a surface that can be seen from the outside when the tire is in use. The outer surface 3s of at least one of the pair of sidewall portions 3 includes at least one recessed mark 5 recessed from a reference plane 3c. In FIG. 1, "Z," "E," and "N" are shown as the recessed marks 5, but the present disclosure is not limited to such an embodiment.

[0011] Fig. 2 shows an enlarged plan view of the recessed mark 5 of Fig. 1. Fig. 3 shows an end view taken along line AA of Fig. 2. As shown in Figs. 2 and 3, the recessed mark 5 includes a bottom surface 6 and an inner wall surface 7 that extends around the bottom surface 6 in the depth direction of the recessed mark 5. As shown in Fig. 3, the depth d1 of the recessed mark 5 is, for example, 1.5 mm or less, preferably 1.0 mm or less, and more preferably 0.4 to 0.7 mm.

[0012] In this specification, unless otherwise specified, various dimensions are measured for a tire in its normal state. In the case of a pneumatic tire for which various standards are established, "normal state" refers to a state in which the tire is mounted on a normal rim, inflated to the normal internal pressure, and no load is applied. In the case of a tire for which various standards are not established, the normal state refers to a standard use state according to the intended use of the tire, and no load is applied.

[0013] A "genuine rim" is a rim that is defined for each tire by the standard system that includes the standard on which the tire is based. For example, in the case of JATMA, it is called a "standard rim," in the case of TRA, it is called a "design rim," and in the case of ETRTO, it is called a "measuring rim."

[0014] "Normal internal pressure" is the air pressure specified for each tire by each standard in the 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."

[0015] As shown in Fig. 2, the contour 5o of the recessed mark 5 is formed by the inner wall surface 7. The bottom surface 6 and the inner wall surface 7 have an optical contrast, which enhances the visibility of the recessed mark 5 when observing the tire. In this specification, "when observing the tire" means when the sidewall portion 3 of the tire 1 mounted on a vehicle is observed while the vehicle is stopped.

[0016] The bottom surface 6 includes a peripheral region 10 extending along the contour 5o of the recessed mark 5 and a main region 9 surrounded by the peripheral region 10. The peripheral region 10 includes a shadow region 11 and a non-shadow region 12. The shadow region 11 is a region where a shadow of the inner wall surface 7 is formed when light is irradiated onto the recessed mark 5 from a first direction. The non-shadow region 12 is a region where a shadow of the inner wall surface 7 is not formed under the above assumption. In FIG. 2, the shadow region 11 and the non-shadow region 12 are conceptually illustrated with dots to facilitate understanding of the contents of the present disclosure. The first direction refers to any one direction, and in this embodiment, the direction of arrow C extending from an upper left diagonal position to a lower right diagonal position corresponds to the first direction.

[0017] The shadow region 11 and the non-shadow region 12 are formed by an uneven surface 15. FIG. 4 is an enlarged perspective view of region B in FIG. 2, conceptually illustrating the uneven surface 15. As shown in FIG. 4, the uneven surface 15 is provided with a plurality of minute protrusions 20, which disperse and reflect light in multiple directions. Therefore, when observing the tire, the uneven surface 15 is observed as an area with a high degree of blackness, thereby enhancing the contrast with other parts.

[0018] As shown in FIG. 2, in the present disclosure, the width W2 of the uneven surface 15 in the non-shadowed region 12 is smaller than the width W1 of the uneven surface 15 in the shadowed region 11. Note that the width W1 and the width W2 each refer to a width measured in a direction perpendicular to the outline 5o of the recessed mark 5. By adopting the above-described configuration, the tire of the present disclosure can exhibit excellent visibility of the recessed mark 5 in the sidewall portion 3. The mechanism behind this is as follows.

[0019] Generally, when observing a tire, the position of the concave mark in the tire rotation direction varies. For this reason, it is expected that light will hit the concave mark from various directions. For example, when observing a tire, the direction of light will be opposite when the concave mark is located at the top of the tire in the radial direction (hereinafter, this state may be referred to as "the concave mark is at the 12 o'clock position") and when the concave mark is located at the bottom of the tire in the radial direction (hereinafter, this state may be referred to as "the concave mark is at the 6 o'clock position").

[0020] On the other hand, conventional recessed marks can lose visibility and three-dimensional effect depending on the direction of light. For example, even if a recessed mark has relatively high visibility at the 12 o'clock position, its outline can be difficult to see and the three-dimensional effect can be lost when the mark is at the 6 o'clock position.

[0021] In contrast, in the present disclosure, the shadow region 11 and non-shadow region 12 of the concave mark 5 are formed by an uneven surface 15 on which a plurality of minute protrusions 20 are arranged, and the width W2 of the non-shadow region 12 is smaller than the width W1 of the shadow region 11. This makes it easy to see the outline 5o of the concave mark 5 regardless of the direction from which light hits the concave mark 5. Furthermore, regardless of the position of the concave mark 5 in the tire rotation direction, the shadow region 11 and non-shadow region 12 give the impression that light is being irradiated from a specific direction (the first direction), giving the concave mark 5 a three-dimensional appearance. Due to this mechanism, the tire 1 of the present disclosure can exhibit excellent visibility of the concave mark 5 in the sidewall portion 3.

[0022] As described above, the present disclosure can improve the visibility of the recessed mark 5 without increasing the depth d1 (shown in FIG. 3) of the recessed mark 5. This allows the depth d1 to be set smaller than conventional depths, which is expected to improve tire durability. Furthermore, by setting the depth d1 to a small value, the air resistance experienced by the sidewall portion 3 when the tire 1 rotates is reduced, which is expected to reduce the rolling resistance of the tire.

[0023] The following describes the configuration of this embodiment in more detail. Note that each configuration described below represents a specific aspect of this embodiment. Therefore, it goes without saying that the present disclosure can achieve the above-described effects even if it does not include the configurations described below. Furthermore, even if any one of the configurations described below is applied alone to a tire of the present disclosure having the above-described characteristics, performance improvement corresponding to each configuration can be expected. Furthermore, when several of the configurations described below are applied in combination, combined performance improvement corresponding to each configuration can be expected.

[0024] 2 and 3, the main region 9 and the inner wall surface 7 of the bottom surface 6 of this embodiment are not provided with minute protrusions 20 and are formed as flat surfaces. This increases the contrast with the uneven surface 15, improving visibility. However, this is not limited to this, and the main region 9 and the inner wall surface 7 may have minute protrusions 20 arranged in a manner that creates a contrast with the peripheral region 10.

[0025] 2, in this embodiment, as a desirable aspect, the uneven surface 15 is formed in an area that is preferably 50% or more, and more preferably 80% or more of the area where the shadow of the inner wall surface 7 is formed when light is irradiated onto the recessed mark 5 from a first direction. As an even more desirable aspect, in this embodiment, the uneven surface 15 is formed in the entire area where the shadow of the inner wall surface 7 is formed. However, the present disclosure is not limited to such an aspect, and the uneven surface 15 may be formed in only a part of the area where the shadow of the inner wall surface 7 is formed.

[0026] The smaller the variation in the width W1 of the uneven surface 15 of the shadow region 11 in the longitudinal direction of the contour 5o, the more the three-dimensional effect of the concave mark 5 can be enhanced. Therefore, the difference between the maximum and minimum values ​​of the width W1 is preferably 20% or less of the maximum value. More preferably, in this embodiment, the width W1 is substantially constant in the longitudinal direction of the contour 5o. Furthermore, the width W1 is preferably 5% to 15% of the length L1 (shown in FIG. 1) of the concave mark 5 in the tire radial direction.

[0027] To ensure improved visibility, the uneven surface 15 of width W2 is configured over preferably 50% or more, and more preferably 80% or more of the entire length (length along the contour 5o) of the non-shadow region 12. In this embodiment, the uneven surface 15 of width W2 is configured over substantially the entire non-shadow region 12.

[0028] The smaller the variation in the width W2 of the uneven surface 15 of the non-shadow region 12 in the longitudinal direction of the contour, the greater the three-dimensional effect of the concave mark 5. For this reason, the difference between the maximum and minimum values ​​of the width W2 is preferably 20% or less of the maximum value. As a more preferable aspect, in this embodiment, the width W2 is substantially constant in the longitudinal direction of the contour 5o. The width W2 of the uneven surface 15 of the non-shadow region 12 is, for example, 20% to 70% of the width W1 of the uneven surface 15 of the shadow region 11, and preferably 30% to 50%. This makes it possible to improve the visibility of the contour 5o in the non-shadow region 12 while maintaining the three-dimensional effect of the concave mark 5 when observing the tire.

[0029] In the present disclosure, the shape of the microprotrusions 20 is not limited as long as they are effective in dispersing and reflecting light on the uneven surface 15. As shown in Fig. 4, in a preferred embodiment, the multiple microprotrusions 20 are configured to have the same size and shape.

[0030] Fig. 5 shows an enlarged cross-sectional view of the microprotrusions 20 of this embodiment. As shown in Fig. 5, the microprotrusions 20 of this embodiment are, for example, conical in shape with rounded tops 21. As a result, in a front view of the recessed mark 5, each of the multiple microprotrusions 20 has a circular outline.

[0031] The diameter D1 of the micro-projections 20 is, for example, 0.2 to 0.6 mm, and preferably 0.3 to 0.5 mm. The diameter D1 means the diameter of the base of the micro-projections 20. The height h1 of the micro-projections 20 is, for example, 0.2 to 0.6 mm, and preferably 0.3 to 0.5 mm. 2 The average number of microprotrusions 20 per unit is, for example, 2 to 8. However, the present disclosure is not limited to such an embodiment.

[0032] Various shapes can be adopted for the microprotrusions 20. Fig. 6 shows an enlarged cross-sectional view of a microprotrusion 20 according to another embodiment of the present disclosure. As shown in Fig. 6, in this embodiment, minute recesses 22 are formed on the tops 21 of the microprotrusions 20. The microprotrusions 20 having such recesses 22 can disperse and reflect light in various directions, further increasing the blackness of the textured surface 15.

[0033] 7 is an enlarged plan view of region B in FIG. 2, showing the arrangement of the minute protrusions 20 in a front view of the recessed mark 5. As shown in FIG. 7, it is desirable that the shadowed region 11 and the non-shadowed region 12 each include an area where the plurality of minute protrusions 20 are arranged in a close-packed manner. In a more desirable embodiment, the plurality of minute protrusions 20 are arranged in a close-packed manner in 80% or more of the shadowed region 11 and the non-shadowed region 12. This further improves the blackness of the shadowed region 11 and the non-shadowed region 12, thereby improving the visibility of the recessed mark 5.

[0034] 2, the peripheral region 10 includes a boundary 23 between the uneven surface 15 and an area where the multiple microprotrusions 20 are not arranged. Also, as shown in FIG. 4, the shadowed region 11 and the non-shadowed region 12 each include a boundary protrusion row 25 in which the microprotrusions 20 are arranged to form the boundary 23.

[0035] The boundary protrusion array 25 has a plurality of microprotrusions 20 arranged such that the contours of the microprotrusions 20 are in contact with each other. As shown in FIG. 7 , in a front view of the concave mark 5, an imaginary line 27 connecting the centroids 20c of the contours of the microprotrusions 20 included in the boundary protrusion array 25 is non-zigzag and does not include any bends at angles of 120° or less. Such a boundary protrusion array 25 can make the boundary portion 23 closer to a straight line, which helps to further increase the contrast between the uneven surface 15 and the area where the microprotrusions 20 are not arranged. In this embodiment, the contours of the microprotrusions 20 are circular, and the centroid 20c corresponds to the center of the circular contour.

[0036] If the imaginary line 27 is bent, it is desirable that the imaginary line 27 bend at an angle of 150° or more. In a more desirable embodiment, the imaginary line 27 is a straight line. This can further enhance the above-mentioned effects.

[0037] Although a tire according to one embodiment of the present disclosure has been described in detail above, the present disclosure is not limited to the above-described specific embodiment and can be modified and implemented in various aspects. [Example]

[0038] A tire of size 245 / 40ZR18 having the recessed mark shown in Figure 1 was prototyped based on the specifications in Table 1. Additionally, as a comparative example, a tire was prototyped in which the shaded area had an uneven surface but the non-shaded area did not have an uneven surface. The comparative tire was substantially the same as the tire shown in Figure 1, except for the above-mentioned points. The visibility of each test tire was tested by checking the visibility of the recessed mark at the 12 o'clock position or the 6 o'clock position, and the three-dimensional effect of the recessed mark. The common specifications and test methods for each test tire are as follows: Length of the recessed mark in the radial direction of the tire L1: 20 mm Depth of concave mark d1: 0.6 mm

[0039] <Visibility of the concave mark at the 12 o'clock or 6 o'clock position> The test tire was mounted on a vehicle, and the visibility of the concave mark (mainly the clarity of the contour of the concave mark) was evaluated when the concave mark was at the 12 o'clock or 6 o'clock position. The results are shown as a score with each visibility of the comparative example being 100 points, with a higher score indicating better visibility at each position.

[0040] <Three-dimensional effect of concave mark> A rectangular rubber sample (40 x 200 mm) containing a concave mark was cut from the tire, and the three-dimensional effect of the concave mark was evaluated comprehensively when observed from various directions. The results are shown as a score with the three-dimensional effect of the comparative example being 100 points, and the higher the score, the better the three-dimensional effect of the concave mark. The test results are shown in Table 1.

[0041] [Table 1]

[0042] As shown in Table 1, the recessed marks of the examples have improved visibility at each position and also have improved three-dimensional effect. In other words, it has been confirmed that the recessed marks of the sidewall portion of the present disclosure exhibit excellent visibility.

[0043] [Note] The present disclosure includes the following aspects.

[0044] [Disclosure 1] 1. A tire including a pair of sidewall portions, an outer surface of at least one of the pair of sidewall portions includes at least one recessed mark recessed from a reference plane; the concave mark includes a bottom surface and an inner wall surface extending in a depth direction of the concave mark around the bottom surface, the bottom surface includes a peripheral region extending along the contour of the recessed mark and a main region surrounded by the peripheral region; the peripheral region includes a shadow region where a shadow of the inner wall surface is formed when light is irradiated onto the recessed mark from a first direction, and a non-shadow region where a shadow of the inner wall surface is not formed, the shadowed area and the non-shadowed area are formed by an uneven surface on which a plurality of minute protrusions are arranged, a width W2 of the non-shadowed region measured in a direction perpendicular to the contour of the uneven surface is smaller than a width W1 of the shadowed region measured in a direction perpendicular to the contour of the uneven surface; tire. [Disclosure 2] The tire according to Disclosure 1, wherein the width W2 of the uneven surface of the non-shadowed region is 20% to 70% of the width W1 of the uneven surface of the shadowed region. [Disclosure 3] The tire according to Disclosure 1 or 2, wherein the width W1 of the uneven surface of the shadow region is 5% to 15% of the length of the recessed mark in the tire radial direction. [Disclosure 4] When viewed from the front of the recessed mark, each of the plurality of minute protrusions has a circular outline, The tire according to any one of Disclosures 1 to 3, wherein the shadowed region and the non-shadowed region each include a region in which the plurality of microprotrusions are arranged in a close-packed manner. [Disclosure 5] the peripheral region includes a boundary between the uneven surface and a region where the plurality of microprotrusions are not arranged, the shadow area and the non-shadow area each include a boundary protrusion row in which the microprotrusions are arranged to form the boundary portion, A tire described in any one of Disclosures 1 to 4, wherein, in a front view of the recessed mark, an imaginary line connecting the centroids of the contours of the minute protrusions included in the boundary protrusion row is non-zigzag and does not include any portions bent at an angle of 120° or less. [Disclosure 6] The tire described in Disclosure 5, wherein the imaginary line is a straight line or bent at an angle of 150° or more. [Disclosure 7] When viewed from the front of the recessed mark, each of the plurality of minute protrusions has a circular outline, The tire according to Disclosure 5 or 6, wherein the boundary projection row has a plurality of the minute projections arranged so that the contours are in contact with each other. [Explanation of symbols]

[0045] 3 Sidewall 3s outer surface 5 Concave mark 5o Contour 6 Bottom 7 Inner wall surface 9 Main area 10 Peripheral Regions 11 Shadow area 12 Non-shadow area 15 Uneven surface 20 Microprotrusions W1 Width of the uneven surface of the shadow area W2 Width of the uneven surface in the non-shadowed area

Claims

1. 1. A tire including a pair of sidewall portions, an outer surface of at least one of the pair of sidewall portions includes at least one recessed mark recessed from a reference plane; the concave mark includes a bottom surface and an inner wall surface extending in a depth direction of the concave mark around the bottom surface, the bottom surface includes a peripheral region extending along the contour of the recessed mark and a main region surrounded by the peripheral region; the peripheral region includes a shadow region in which a shadow of the inner wall surface is formed when light is irradiated onto the recessed mark from a first direction, and a non-shadow region in which a shadow of the inner wall surface is not formed, the shadowed area and the non-shadowed area are formed by an uneven surface on which a plurality of minute protrusions are arranged, a width W2 of the non-shadowed region measured in a direction perpendicular to the contour of the uneven surface is smaller than a width W1 of the shadowed region measured in a direction perpendicular to the contour of the uneven surface; tire.

2. 2. The tire of claim 1, wherein the width W2 of the uneven surface of the non-shadowed region is 20% to 70% of the width W1 of the uneven surface of the shadowed region.

3. 3. The tire according to claim 1, wherein the width W1 of the uneven surface of the shadow region is 5% to 15% of the length of the recessed mark in the tire radial direction.

4. When viewed from the front of the recessed mark, each of the plurality of minute protrusions has a circular outline, The tire according to claim 1 , wherein the shadowed area and the non-shadowed area each include an area in which the plurality of microprotrusions are arranged in a close-packed manner.

5. the peripheral region includes a boundary between the uneven surface and a region where the plurality of microprotrusions are not arranged, the shadow area and the non-shadow area each include a boundary protrusion row in which the microprotrusions are arranged to form the boundary portion, 5. The tire according to claim 1, wherein, in a front view of the concave mark, an imaginary line connecting the centroids of the contours of the minute protrusions included in the boundary protrusion row is non-zigzag and does not include any portion bent at an angle of 120° or less.

6. The tire according to claim 5 , wherein the imaginary line is a straight line or bent at an angle of 150° or more.

7. When viewed from the front of the recessed mark, each of the plurality of minute protrusions has a circular outline, The tire according to claim 5 or 6, wherein the boundary projection row includes a plurality of the minute projections arranged so that the contours are in contact with each other.

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