pneumatic tires

Abstract

To provide a pneumatic tire capable of making unevenness on an outer surface of a side wall less conspicuous and improving an aesthetic property in the side wall.SOLUTION: A pneumatic tire includes a band-shaped decoration pattern formed on an outer surface of a side wall and extending along a tire circumferential direction. The decoration pattern is formed by repeatedly arranging a unit pattern in the tire circumferential direction. The unit pattern includes a concentric arc pattern formed by concentrically arraying an arc having a center in a tire radial inside further than the decoration pattern. An array pitch of the arc becomes larger toward a tire radial outside.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a pneumatic tire having a strip-shaped decorative pattern formed on the outer surface of a sidewall.

Background Art

[0002] A pneumatic tire is manufactured by vulcanizing and molding a green tire formed by combining various tire components. When the pneumatic tire is inflated, a joint portion of a strip-shaped tire component (for example, a carcass) may appear as local irregularities on the outer surface of the sidewall, and such irregularities may cause a decrease in the appearance quality of the tire.

[0003] In order to make such local irregularities less noticeable, it is known to form a strip-shaped decorative pattern on the outer surface of the sidewall, for example, as described in Patent Document 1. However, in recent years, not only making the irregularities less noticeable, but further improvements for enhancing the aesthetic property of the sidewall by the decorative pattern have been desired.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a pneumatic tire that can make irregularities on the outer surface of the sidewall less noticeable and enhance the aesthetic property of the sidewall.

Means for Solving the Problems

[0006] The pneumatic tire of the present disclosure is It features a band-shaped decorative pattern formed on the outer surface of the sidewall, extending along the circumferential direction of the tire. The aforementioned decorative pattern is formed by repeatedly arranging a unit pattern in the circumferential direction of the tire. The aforementioned unit pattern includes a concentric arc pattern in which arcs having their centers located inward in the tire radial direction from the aforementioned decorative pattern are arranged concentrically. The arrangement pitch of the aforementioned arcs increases towards the outer side in the radial direction of the tire. [Brief explanation of the drawing]

[0007] [Figure 1] A schematic meridional cross-sectional view of a tire, illustrating an example of a pneumatic tire according to this embodiment. [Figure 2] Front view of the pneumatic tire according to this embodiment, viewed from the tire axis direction. [Figure 3] Enlarged view showing part of the decorative pattern [Figure 4] Enlarged view showing the unit pattern [Figure 5] Cross-sectional view taken along arrow XX in Figure 4. [Figure 6] Diagram showing variations of decorative patterns [Figure 7] Diagram showing variations of decorative patterns [Figure 8] Diagram showing variations of decorative patterns [Figure 9] Diagram showing variations of decorative patterns [Figure 10] Diagram showing variations of decorative patterns [Figure 11] Diagram showing variations of decorative patterns [Modes for carrying out the invention]

[0008] Embodiments of the pneumatic tire of this disclosure will be described with reference to the drawings.

[0009] As shown in Figure 1, the pneumatic tire T comprises a pair of bead portions 1, a pair of sidewalls 2 extending radially outward from each of the pair of bead portions 1, and a tread 3 connected to the radially outer ends of each of the pair of sidewalls 2. The tire T further comprises a carcass 4 provided between the pair of bead portions 1, a belt layer 5 laminated on the radially outer side of the carcass 4, and an inner liner 6 disposed on the inner surface of the tire.

[0010] Here, the tire radial direction is the direction along the diameter of tire T, and corresponds to the vertical direction in Figure 1. In Figure 1, the upper side is the outer side in the tire radial direction, and the lower side is the inner side in the tire radial direction. The tire axial direction is the direction parallel to the rotation axis of tire T, and corresponds to the left-right direction in Figure 1. The side approaching the tire equatorial plane TE is the inner side in the tire axial direction, and the side moving away from the tire equatorial plane TE is the outer side in the tire axial direction. The tire circumferential direction is the direction around the rotation axis of tire T.

[0011] An annular bead core 1a is embedded in the bead portion 1. The bead core 1a is formed by covering a converging body such as steel wire with rubber. A bead filler 1b is positioned on the radially outer side of the bead core 1a. The bead filler 1b is formed of triangular-shaped rubber extending radially outward from the bead core 1a. Rim strip rubber 7, which forms the outer surface of the bead portion 1, is provided on the axially outer side of the bead core 1a and bead filler 1b.

[0012] The carcass 4 extends in a toroidal shape across a pair of bead portions 1. The carcass 4 is wound from the inside to the outside in the tire axial direction, sandwiching the bead core 1a and the bead filler 1b. The carcass 4 is formed from carcass plies formed by covering carcass cords with rubber. The carcass cords are aligned in a direction substantially perpendicular to the tire circumferential direction (for example, a direction at an angle of 75 to 90 degrees with respect to the tire circumferential direction). Sidewall rubber 8, which forms the outer surface of the sidewall 2, is provided on the tire axial outer side of the carcass 4.

[0013] The belt layer 5 is formed by a plurality of belt plies 5a and 5b laminated on each other. The belt plies 5a and 5b are each formed by rubber-coating belt cords aligned in a direction inclined with respect to the tire circumferential direction. The belt plies 5a and 5b are laminated such that the belt cords cross each other in opposite directions therebetween. A tread rubber 9 is provided on the outer side in the tire radial direction of the belt layer 5. The tread rubber 9 is provided with a groove portion including a circumferential groove 9a, and a tread pattern corresponding to required tire performance and usage conditions is formed.

[0014] As shown in FIG. 2, a belt-like decorative pattern 20 extending along the tire circumferential direction is formed on the outer surface of the sidewall 2. For illustration purposes, in FIG. 2, the decorative pattern 20 is depicted by gray shading, but actually, a pattern as shown in FIG. 3 is applied. In the present embodiment, the decorative pattern 20 extends in an arc shape (non-annular) along the tire circumferential direction, but it is not limited thereto and may extend in an annular shape along the tire circumferential direction. The decorative pattern 20 is formed by an uneven pattern formed on the sidewall rubber 8 by vulcanization molding.

[0015] In the present embodiment, the decorative pattern 20 is formed in a certain region in the tire radial direction including the tire maximum width position 2M. Therefore, the inner peripheral edge 20a of the decorative pattern 20 is disposed on the inner side in the tire radial direction than the tire maximum width position 2M, and the outer peripheral edge 20b of the decorative pattern 20 is disposed on the outer side in the tire radial direction than the tire maximum width position 2M. The tire maximum width position 2M is the position where the profile line of the sidewall 2 in the tire meridian plane is the farthest from the tire equatorial plane TE in the tire axial direction. This profile line is the contour of the sidewall 2 excluding protrusions such as rim protectors.

[0016] FIG. 3 is an enlarged view showing a part of the decorative pattern 20. The decorative pattern 20 is formed by repeatedly arranging unit patterns 30 in the tire circumferential direction. The unit pattern 30 is arranged at a constant pitch angle θ1 along the tire circumferential direction. The pitch angle θ1 is an angle formed by tire radial lines DL adjacent to each other in the tire circumferential direction. The tire radial line DL is a virtual line extending in the tire radial direction through the center C of an arc Ar described later. The pitch angle θ1 is preferably 1 degree or more. The pitch angle θ1 is preferably 5 degrees or less, and more preferably 3 degrees or more. Also, the pitch angle θ1 is preferably smaller than a range angle θ2 described later, but is not limited thereto.

[0017] FIG. 4 is an enlarged view showing the unit pattern 30, and is drawn by extracting one of the plurality of unit patterns 30 forming the decorative pattern 20. The unit pattern 30 is arranged at a constant range angle θ2 along the tire circumferential direction. The range angle θ2 is, for example, 5 to 10 degrees. The unit pattern 30 includes a concentric arc pattern 40 in which arcs Ar having a center C are arranged concentrically inside the decorative pattern 20 in the tire radial direction. FIG. 4 shows an example in which the unit pattern 30 includes only the concentric arc pattern 40. The arrangement pitch of the arcs Ar increases toward the outer side in the tire radial direction (upper side in FIG. 4).

[0018] Due to the arrangement pitch of the arcs Ar increasing toward the outer side in the tire radial direction, in the region on the inner side in the tire radial direction of the decorative pattern 20, a complex pattern is formed by relatively fine elements, and the unevenness of the outer surface of the sidewall 2 caused by the joint portion of tire components such as the carcass 4 can be made less noticeable. Also, in the region on the outer side in the tire radial direction of the decorative pattern 20, since the extending direction of the elements forming the pattern becomes closer to the tire circumferential direction, the unevenness of the outer surface of the sidewall 2 that tends to appear along the tire radial direction can be made less noticeable.

[0019] In the area of ​​the decorative pattern 20 on the inner side in the tire radial direction, the relatively small arrangement pitch of the arcs Ar reduces the gaps between the protrusions 31 (described later), changing the degree of diffuse reflection of light and making it appear relatively darker (blacker). Conversely, in the area of ​​the decorative pattern 20 on the outer side in the tire radial direction, the relatively large arrangement pitch of the arcs Ar makes it appear relatively brighter. As a result, it is easier to create variations in shade of black within the decorative pattern 20, enhancing the aesthetic appeal of the sidewall 2.

[0020] When the pitch angle θ1 is smaller than the range angle θ2, adjacent unit patterns 30 in the tire circumferential direction overlap each other, as shown in Figure 3. This increases the number of intersections between arcs Ar, making the pattern more complex and thus enhancing the effect of making the irregularities on the outer surface of the sidewall 2 less noticeable. Furthermore, the areas around these intersections appear relatively darker (blacker), making it easier to create variations in shade of black within the decorative pattern 20, thereby improving the aesthetic appeal of the sidewall 2. From the viewpoint of enhancing these improvements, in this embodiment, the pitch angle θ1 is made smaller than half of the range angle θ2. As a result, adjacent unit patterns 30 in the tire circumferential direction overlap each other beyond the tire radial line DL passing through the center C of the arc Ar.

[0021] As shown in Figure 4, in this embodiment, one concentric arc pattern 40 is formed by five arcs Ar. In this specification, each arc is individually referred to as "arc Ar1 to Ar5," but they are collectively referred to as "arc Ar." The number of arcs Ar forming one concentric arc pattern 40 is preferably 3 or more, and more preferably 5 or more. Furthermore, the number of arcs Ar forming one concentric arc pattern 40 is preferably 20 or less, and more preferably 10 or less. Note that although arc Ar5 reaching the outer edge 20b is divided into two, their centers and radii coincide, so it is counted as one arc Ar (arc Ar5).

[0022] In this embodiment, the concentric arc pattern 40 is formed only by arcs Ar extending from the inner peripheral edge 20a of the decorative pattern 20. Each of the arcs Ar1 to Ar5 that form the concentric arc pattern 40 has both ends connected to the inner peripheral edge 20a. However, it is not limited to this, and arcs that terminate within the decorative pattern 20 without being connected to the inner peripheral edge 20a, or arcs whose ends are connected to other adjacent arcs, etc., may also be included. It is preferable that the concentric arc pattern 40 includes arcs Ar, such as arc Ar5, that reach the outer peripheral edge 20b. It is preferable that the number of arcs Ar that reach the outer peripheral edge 20b in a single concentric arc pattern 40 is 3 or less.

[0023] As previously mentioned, the arrangement pitch of the circular arcs Ar increases toward the outer side in the radial direction of the tire. The arrangement pitches P1 to P4 of the circular arcs Ar shown in Figure 4 are, for example, P1=3.0mm, P2=4.0mm, P3=5.0mm, and P4=6.0mm. In this case, the difference between adjacent arrangement pitches is constant at 1.0mm, but it is not limited to this and may be variable. To ensure the effect of enhancing the aesthetic appearance of the sidewall 2, the difference between adjacent arrangement pitches is preferably 0.5mm or more, and more preferably 1.0mm or more. Furthermore, to ensure the effect of making the irregularities on the outer surface of the sidewall 2 less noticeable, the difference between adjacent arrangement pitches is preferably 8.0mm or less, and more preferably 6.0mm or less.

[0024] As the arrangement pitch of arcs Ar increases toward the outer radial side of the tire, the change in the radius of arc Ar increases toward the outer radial side of the tire. In one example, the radii of arcs Ar1 to Ar5 are 5.0 mm, 8.0 mm, 12.0 mm, 17.0 mm, and 23.0 mm, respectively. In this case, the change in the radius of arc Ar gradually increases to 3.0 mm, 4.0 mm, 5.0 mm, and 6.0 mm.

[0025] In this embodiment, the curvature of the arcs Ar1 to Ar5 that form the concentric arc pattern 40 decreases toward the outer side in the tire radial direction. However, this is not limited to this, and for example, when comparing the curvature of a certain arc Ar with the curvature of an arc Ar located inside that arc Ar in the tire radial direction, the curvature of the arc Ar located on the outer side in the tire radial direction may be greater.

[0026] In this embodiment, the concentric arc pattern 40 (including the unit pattern 30) is formed by protrusions 31 projecting outward in the tire axial direction, as illustrated in Figure 5. The width W31 of the protrusions 31 is, for example, 0.1 to 0.8 mm. The projection height H31 of the protrusions 31 is, for example, 0.2 mm or more. The pitch P31 of the protrusions 31, which corresponds to the arrangement pitch of the arcs Ar, is, for example, 0.5 to 8.0 mm. The cross-sectional shape of the protrusions 31 is triangular, but is not limited to this, and may be other shapes such as rectangles, trapezoids, or triangles with rounded vertices.

[0027] In this embodiment, a recess 22 is provided in a band shape on the outer surface of the sidewall 2, recessed from the profile line, and a decorative pattern 20 is formed within the recess 22. This protects the decorative pattern 20 from dirt and damage, and maintains the improved appearance for as long as possible. In Figure 5, the outer surface along the profile line is shown by a dashed line. The protrusion 31 projects from the bottom surface 22a of the recess 22. The inner peripheral edge 20a and the outer peripheral edge 20b are formed by the wall surface of the recess 22, respectively. The depth D22 of the recess 22 is, for example, 0.2 to 1.5 mm. The projection height H31 of the protrusion 31 is smaller than the depth D22, but is not limited to this, and may be the same as or greater than the depth D22. The protrusion 31 may project from the outer surface of the sidewall 2 along the profile line, rather than from the bottom surface 22a of the recess 22.

[0028] Figures 6-11 show variations of the decorative pattern. These variations, apart from the configuration described below, have the same configuration as the decorative pattern 20 described with reference to Figures 3-5. Therefore, we will omit the commonalities and focus mainly on the differences. Components identical to those already described are denoted by the same reference numerals, and redundant explanations are omitted.

[0029] In the above-described embodiment, an example was shown in which each of the arcs Ar forming the concentric arc pattern 40, when viewed from the tire axis direction, is an arc of a perfect circle (a circle consisting of the locus of points equally distanced from the center C). However, it is not limited to this, and may also be an elliptical arc (i.e., an elliptical arc). Therefore, for example, the concentric arc pattern 40 may be in a form in which arcs Ar, which are elliptical arcs with their major axes oriented in the tire radial direction, are arranged concentrically, as shown in Figure 6. Alternatively, for example, the concentric arc pattern 40 may be in a form in which arcs Ar, which are elliptical arcs with their minor axes oriented in the tire radial direction, are arranged concentrically, as shown in Figure 7.

[0030] As shown in Figures 6 and 7, by forming a concentric arc pattern 40 with an elliptical arc Ar, it is easy to form a concentric arc pattern 40 of an appropriate size in light of the width, length, pitch angle θ1, and range angle θ2 of the decorative pattern 20. Furthermore, according to the configuration in Figure 6, the pitch angle can be set small while maintaining the overlap ratio of the unit patterns 30, which is convenient for increasing the number of elements that make up the decorative pattern 20. According to the configuration in Figure 7, the effect of making the irregularities on the outer surface of the sidewall 2, which tend to appear along the tire diameter direction, less noticeable is enhanced by increasing the number of elements that extend in the circumferential direction of the tire.

[0031] Figure 8 shows an example in which an array of unit patterns 50, repeated in the circumferential direction of the tire, is placed on the radially outer side of the array of unit patterns 30. The concentric arc patterns 40 included in the unit patterns 30 and the concentric arc patterns 60 included in the unit patterns 50 are arranged in a staggered pattern along the circumferential direction of the tire. This creates a more complex pattern, enhancing the effect of making the irregularities on the outer surface of the sidewall 2 less noticeable. In the concentric arc patterns 60 as well, the arrangement pitch of the arcs increases toward the radially outer side of the tire. The arcs forming the concentric arc patterns 60 have their centers at the intersections of the outermost arcs of the concentric arc patterns 40, but are not limited to this.

[0032] Figure 9 shows an example in which the unit pattern 30 further includes a radial pattern 70 formed by multiple straight lines 71 that extend radially from the center C of the arc and pass through the intersections of the arcs Ar. By combining the radial pattern 70 formed by straight lines 71 with the concentric arc pattern 40 formed by curves, the pattern becomes more complex, improving the effect of making the irregularities on the outer surface of the sidewall 2 less noticeable. In addition, since the straight lines 71 extend from the center C, overlapping patterns can be efficiently generated. The fact that the straight lines 71 pass through the intersections of the arcs Ar is useful in dividing the area into appropriately sized sections and increasing the complexity of the pattern. From the viewpoint of generating many overlapping patterns, it is preferable that the straight lines 71 reach the outermost arc (arc Ar5 in Figure 4) or the outer edge 20b of the arc pattern 40.

[0033] In Figure 9, a single unit pattern 30 containing a radial pattern 70 is depicted. However, each of the unit patterns 30 arranged in the circumferential direction of the tire may contain a radial pattern 70, or the unit patterns 30 may contain a radial pattern 70 at predetermined intervals (for example, one or two). For the sake of explanation, the elements of the radial pattern 70 are shown inside the inner circumference 20a in the radial direction of the tire (below in Figure 9), but these are not actually visible. Also, to facilitate distinction, the radial pattern 70 is drawn with thicker lines than the concentric arc pattern 40, but their relative sizes are not particularly limited and they may be of similar thickness. The same applies to the radial patterns 80 and 90 described later.

[0034] Figure 10 shows an example in which the unit pattern 30 further includes a radial pattern 80 formed by multiple curves 81 that extend radially from the center C of the arc and pass through the intersections of the arcs Ar. This increases the complexity of the pattern, making the irregularities on the outer surface of the sidewall 2 less noticeable. The curves 81 are formed by arcs (or elliptical arcs) that are convex outward in the radial direction of the tire, but are not limited to this. The rest of the structure and function are the same as those of the radial pattern 70 shown in Figure 9, so a redundant explanation will be omitted.

[0035] Figure 11 shows an example in which the unit pattern 30 further includes a radial pattern 90 formed by multiple bent lines 91 that extend radially from the center C of the arc and pass through the intersections of the arcs Ar. This reduces monotony and increases complexity, thereby making the irregularities on the outer surface of the sidewall 2 less noticeable. The rest of the structure and function are the same as those of the radial pattern 70 shown in Figure 9, so redundant explanations are omitted. The number of lines (straight lines 71, curves 81, or bent lines 91) forming one radial pattern is preferably 4 or more, more preferably 8 or more, and even more preferably 12 or more.

[0036] [1] As described above, the pneumatic tire of this disclosure has a strip-shaped decorative pattern 20 formed on the outer surface of the sidewall 2 and extending along the circumferential direction of the tire. The decorative pattern 20 is formed by repeatedly arranging unit patterns 30 in the circumferential direction of the tire, and the unit patterns 30 include a concentric arc pattern 40 in which arcs Ar having their center C located inward in the radial direction of the tire from the decorative pattern 20 are arranged concentrically, and the arrangement pitch of the arcs Ar increases toward the radial side of the tire. With this configuration, the irregularities on the outer surface of the sidewall 2 can be made less noticeable and the aesthetic appearance of the sidewall 2 can be enhanced.

[0037] [2] In the pneumatic tire described in [1] above, it is preferable that adjacent unit patterns 30 in the circumferential direction of the tire overlap each other beyond the tire radial line DL passing through the center C of the arc Ar. With this configuration, the irregularities on the outer surface of the sidewall 2 can be made less noticeable, and the aesthetic appearance of the sidewall 2 can be further enhanced.

[0038] [3] In the pneumatic tire described in [1] or [2] above, it is preferable that the number of arcs Ar that form a single concentric arc pattern 40 is 20 or less. This makes it easier to form a relatively bright and visible area, which is useful in improving the aesthetics of the sidewall 2.

[0039] [4] In any one of the above [1] to [3] pneumatic tires, it is preferable that the concentric arc pattern 40 is formed only by arcs Ar extending from the inner peripheral edge 20a of the decorative pattern 20. With this configuration, the effect of making the irregularities on the outer surface of the sidewall 2 less noticeable is enhanced by efficiently creating overlaps of patterns and increasing complexity.

[0040] [5] In any one of the pneumatic tires described in [1] to [4] above, the unit pattern 30 may further include a radial pattern (radial pattern 70, radial pattern 80, or radial pattern 90) formed by multiple lines (straight lines 71, curves 81, or bent lines 91) that extend radially from the center C of the arc Ar and pass through the intersections of the arcs Ar. This enhances the effect of making the irregularities on the outer surface of the sidewall 2 less noticeable.

[0041] While embodiments of this disclosure have been described above, it should be understood that the specific configurations are not limited to these embodiments. The scope of this disclosure is indicated not only by the above-described embodiments but also by the claims, and further includes all modifications within the meaning and scope of equivalence to the claims.

[0042] The pneumatic tire of this disclosure is not limited in any way to the embodiments described above, and various improvements and modifications are possible without departing from the spirit of the disclosure. The various components used in the embodiments described above may be used in any combination. [Explanation of Symbols]

[0043] 2 sidewalls 20 Decorative patterns 20a Inner periphery 30 Unit Pattern 40 Concentric arc pattern 70 Radial pattern 71 straight line 80 Radial pattern 81 curve 90 Radial pattern 91 Bent line Ar arc Center of arc C DL Tire Radial Direction Line

Claims

1. It features a band-shaped decorative pattern formed on the outer surface of the sidewall, extending along the circumferential direction of the tire. The aforementioned decorative pattern is formed by repeatedly arranging a unit pattern in the circumferential direction of the tire. The aforementioned unit pattern includes a concentric arc pattern in which arcs having their centers located inward in the tire radial direction from the aforementioned decorative pattern are arranged concentrically. The arrangement pitch of the aforementioned arcs increases toward the outer radial direction of the tire. A pneumatic tire in which adjacent unit patterns in the circumferential direction of the tire overlap each other, beyond the radial line of the tire passing through the center of the arc.

2. A band-shaped decorative pattern formed on the outer surface of the sidewall and extending along the circumferential direction of the tire, The aforementioned decorative pattern is formed by repeatedly arranging a unit pattern in the circumferential direction of the tire. The aforementioned unit pattern includes a concentric arc pattern in which arcs having their centers located inward in the tire radial direction from the aforementioned decorative pattern are arranged concentrically. The arrangement pitch of the aforementioned arcs increases toward the outer radial direction of the tire. A pneumatic tire, wherein the unit pattern further includes a radial pattern formed by a plurality of straight lines, curves, or bent lines that extend radially from the center of the arc and pass through the intersections of the arcs.

3. The pneumatic tire according to claim 1 or 2, wherein the number of arcs forming one of the concentric arc patterns is 20 or less.

4. The pneumatic tire according to claim 1 or 2, wherein the concentric arc pattern is formed only by the arcs extending from the inner periphery of the decorative pattern.

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