PNEUMATIC TIRE

Abstract

Pneumatic tire which has: a decorative area (11) on a side wall surface (10); and a first reference surface (21) and a plurality of projections (130) projecting from the first reference surface (21) on the decorative area (11), wherein each of the projections (130) has a rib line (131) extending in a first direction and slopes (132), the slopes (132) extending from the rib line (131) to the first reference surface (21) on both sides in a second direction, and the rib line (131) is arranged therebetween, while the slopes (132) are inclined with respect to the first reference surface (21), wherein a length of the rib line (131) is shorter than a length of the projection (130) in the second direction, wherein a plurality of projection lines (23) are formed, in each of which the plurality of projections (130) are connected while contacting each other in the second direction, wherein positions of the projections (130) are shifted in the second direction in the projection lines (23) adjacent to each other, and wherein the heights of both ends of the rib line (131) from the first reference surface (21) are different.

Description

[Technical Field]The present invention relates to a pneumatic tire.[Prior Art]A pneumatic tire having a pattern on a sidewall as described in, for example, JP 2003 / 175707 A is known. Most of the patterns in the near art are formed by arranging many protrusions extending in straight lines at equal intervals. Such a pattern increases the shapeability of the surface of the side wall.KR 10 2016 / 0092068 A describes a sidewall of a tire for a vehicle that is disposed between a shoulder connected to an edge of a tread and a bead, and that has a carbon unit in which three-dimensional carbon grids are alternately and repeatedly disposed on an outer surface of the sidewall. According to this configuration, by applying the three-dimensional grids of the carbon unit to the sidewall of the vehicle tire, the strength of the sidewall block, the riding comfort, the air permeability, and the sound absorbing function thereof can be improved.[Summary of the Invention][Object to be Achieved by Invention]Incidentally, fine patterns have already been widely proposed, but an innovative pattern producing novel optical effects has not yet been widely proposed.In view of the above, it is an object of the present invention to provide a pneumatic tire in which new optical effects can be produced.[Means for Achieving Object]According to an aspect of the invention, there is provided a pneumatic tire having a decorative portion on a sidewall surface, a first reference surface, and a plurality of protrusions protruding from the first reference surface on the decorative portion, each of the protrusions including a rib line extending in a first direction and slopes, the slopes extending from the rib line to the first reference surface on both sides in a second direction, the rib line being interposed therebetween while the slopes are inclined with respect to the first reference surface, a length of the rib line being shorter than a length of the protrusion in the second direction, a plurality of protrusion lines each connected to the plurality of protrusions while contacting each other in the second direction being formed, wherein positions of the protrusions are shifted in the second direction in the protrusion lines adjacent to each other, and wherein the heights of both ends of the rib line are different from the first reference surface.[Advantage of the Invention]In the pneumatic tire according to this embodiment, new optical effects are produced by the reflection of the light on the plurality of slopes.[Brief Description of Drawings]FIG. 1 is a half cross-sectional view of a pneumatic tire in an axial direction.FIG. 2 is a view of a decorative portion on a sidewall surface viewed from an axial direction of the tire.Figure 3 is a perspective view of a portion of a pattern not according to the invention useful for understanding the invention.FIG. 4 is a cross-sectional view of the pattern in a circumferential direction of the tire.FIG. 5 is a view of the pattern viewed from a direction perpendicular to a first reference surface.FIG. 6 is a perspective view of protrusions according to an example of the present invention in which heights of both ends of a rib line are different.FIG. 7 is a cross-sectional view of the pattern in the circumferential direction of the tire according to a modification example showing an example in which the rib lines of the protrusions are lower than a second reference surface.FIG. 8 is a cross-sectional view of the pattern in the circumferential direction of the tire according to a modification example showing an example in which the first reference surface is higher than the second reference surface.[Mode for Carrying Out the Invention]FIG. 1 shows a cross-sectional structure of a pneumatic tire 1 according to an exemplary embodiment. Fig. 1 shows only one half of the structure in an axial direction of the tire, and the pneumatic tire 1 proper is approximately right-left symmetrical with respect to a center line C. The axial direction of the tire is represented by an arrow A in Fig. 1, and a radial direction of the tire is represented by an arrow B in Figs. 1 and 2.The pneumatic tire 1 is provided with bead portions 9 on both sides in the tire axial direction. Each bead part 9 includes a bead core formed of circularly wound steel wire and a rubber bead filler provided on an outer side in a radial direction of the bead core.One or two carcass plies 2 are suspended transversely to the bead portions 9 on both sides in the tire axial direction. The carcass ply 2 is a sheet-shaped member in which many ply cords oriented orthogonally to the circumferential direction of the tire are coated with rubber. The carcass plies 2 form a frame shape of the pneumatic tire 1 between the bead parts 9 on both sides in the tire axial direction and wrap the bead parts 9 by being turned up from the inside to the outside in the tire axial direction and wound around the bead parts 9. Moreover, a rubber chafer 3 is provided at a location on an outer side in the tire axial direction of a turned-up portion 2a in the carcass plies 2.One or more belts 4 are provided on an outer side in the radial direction of the tire of the carcass plies 2, and a belt reinforcing layer 5 is provided on an outer side in the radial direction of the tire of the belts 4. The belt 4 is a member formed of many steel cords coated with rubber. The belt reinforcing layer 5 is a member formed of many organic fiber cords coated with rubber. A tread rubber 6 is provided on an outer side in the radial direction of the belt reinforcing layer 5. On the tread rubber 6, many grooves forming a tread pattern are formed.Sidewall rubbers 7 are provided on both sides of the carcass plies 2 in the tire axial direction. The tread rubber 6 and the sidewall rubber 7 overlap on a support. However, each of the tread rubber 6 and the sidewall rubber 7 may overlap on a tire surface side. A portion of the sidewall rubber 7 on an inner side in the tire radial direction extends near the bead part 9 and covers a part of the rubber chafer 3.A rim line 8 which is a small protrusion having a height of about 1 mm is formed at a boundary between the sidewall rubber 7 and the rubber chafer 3 on the tire surface. The rim line 8 extends circumferentially in the circumferential direction of the tire. Preferably, at the same position as the rim line 8, instead of the rim line 8, a rim protector is provided which protrudes to have an approximately triangular shape in cross section. A range from the rim line 8 or the rim protector to a tread end in the tire radial direction is determined as a sidewall surface 10. Here, the tread end denotes an end in the tire axial direction of a ground contacting surface in the tread rubber 6 when the pneumatic tire 1 contacts a road surface.A sheet-shaped inner liner made of rubber having low air permeability is bonded to the inside of the carcass ply 2. In addition to these members, members such as a belt base and a chafer are provided depending on the functional requirements of the tire.As shown in FIGS. 1 and 2, a decorative portion 11 is provided on at least one of the sidewalls 10 on both sides in the tire axial direction. The decorative portion 11 is in the form of a ring centered on the rotation axis of the tire. The decorative portion 11 is a fixed width portion surrounded by an inner diameter-side line 12 having a circular shape with a small diameter and an outer diameter-side line 13 having a circular shape with a large diameter. The inner diameter side line 12 and the outer diameter side line 13 may be lines formed by recesses / protrusions or steps on the tire surface, or may be virtual lines that do not actually exist.The location of the decorative portion 11 in the tire radial direction may be a location on an outer side in the tire radial direction as the maximum width position of the pneumatic tire 1, and may be a location including the maximum width position of the pneumatic tire 1. Here, the maximum width position of the pneumatic tire 1 is a position at which the length in the tire axial direction is the largest from the surface of the one sidewall 10 in the tire axial direction to the surface of the other sidewall 10 in the tire axial direction.In FIG. 1, the decorative portion 11 is provided to include a location where an interface between the tread rubber 6 and the sidewall rubber 7 appears on the tire surface. The decorative portion 11 may be provided to include a location where a step appears on the surface of the side wall 10 as described above. The location at which the step occurs on the surface of the sidewall 10 typically includes locations at the ends of the elements forming the tire. Such typical locations are, for example, the location of a wound end 2 bof the carcass plies 2 (an end of the wound part 2 aof the carcass plies 2) in the tire axial direction and the like, in addition to the location where the boundary surface between the tread rubber 6 and the sidewall rubber 7 appears on the tire surface as described above.As shown in FIG. 2, labels 15 are provided at two opposing positions in the annular decorative portion 11. The label 15 is formed by arranging a plurality of letters 16 in the circumferential direction of the tire. The plurality of letters 16 may include the name of a manufacturer, a product, a trademark, or the like. These letters 16 are also surrounded by recessed or protruding lines.Figs. 3 to 5 show embodiments useful for understanding the invention.A pattern 14 is provided at a position between the two labels 15. The pattern 14 is formed from certain figures. As shown in FIG. 4, the pattern 14 is provided on a first reference surface 21 which is offset from the second reference surface 22 when a tire surface around the pattern 14 is a second reference surface 22. A contour of the pattern 14 is formed by a step between the first reference surface 21 and the second reference surface 22.Within the contour 17 forming the pattern 14 there are provided a number of protrusions 30 projecting from the first reference surface 21. As shown in FIG. 3 to FIG. 5, each of the protrusions 30 is formed by a rib line 31 extending in a first direction, two slopes 32 extending from the rib line 31 to both sides in a second direction, and two side surfaces 33 descending from both ends in an extending direction of the rib line 31 so as to be perpendicular to the first reference surface 21. The first direction and the second direction are orthogonal to each other in this embodiment. The first direction is represented by an arrow C and the second direction is represented by an arrow D in FIGS. 3 and 5. In FIG. 5, the protrusions 30 are respectively represented by solid lines and the ridge lines 31 by broken lines.The rib line 31 is a straight line extending in the first direction C. The height of the ridge line 31 from the first reference surface 21 is fixed. Accordingly, the heights of both ends of the rib line 31 from the first reference surface 21 are equal. The rib line 31 is the highest portion protruding from the first reference surface 21 in the protrusion 30 located at a higher position than the second reference surface 22 as shown in FIG. 4.The slopes 32 extend from the ridge line 31 to the first reference surface 21 while being inclined with respect to the first reference surface 21. The two slopes 32 on both sides of the rib line 31 have the same inclination angle θ with respect to a direction perpendicular to the first reference surface 21 (see FIG. 4 ). Accordingly, the protrusion 30 has the shape of an isosceles triangle when viewed from the first direction C. An opening angle of the two slopes (namely, 2×θ) is preferably 30 to 150 degrees, and more preferably is 90 to 150 degrees.The slope 32 does not have a rectangular shape including the rib line 31 as one side according to the present invention. A line opposite to the ridge line 31 in the slope 32 is a line of intersection between the slope 32 and the first reference surface 21, and the line of intersection between the slope 32 and the first reference surface 21 corresponds to a second direction end 34 of the protrusion 30.The side surface 33 is an isosceles triangle surface in which an end of the rib line is an apex. The intersecting lines 35 between the side surface 33 and the slopes 32 (see FIG. 3 not according to the invention) are two equal sides of the isosceles triangle, and an intersecting line 36 between the side surface 33 and the first reference surface 21 is a base of the isosceles triangle.The length of the rib line 31 is shorter than the length of the protrusion 30 in the second direction D. However, the length of the protrusion 30 in the second direction D is preferably 30 times or less the length of the rib line 31, and more preferably 20 times or less thereof. Here, the length of the protrusion 30 in the second direction D is also a length of the cut line 36 between the side surface 33 and the first reference surface 21, and the length of the rib line 31 is, for example, 0.8 mm or more to 1.2 mm or less. The height of the protrusion 30 (i.e., the length from the first reference surface 21 to the rib line 31 in the direction perpendicular to the first reference surface 21) is, for example, 0.1 mm or more to 1.5 mm or less.Many (for example, 50 or more) of the protrusions 30 described above are arranged without clearance within the contour 17 of the pattern 14. These protrusions 30 are arranged such that the first direction C corresponds to the radial direction of the tire and the second direction D corresponds to the circumferential direction of the tire.A plurality of protrusions 30 are connected in the circumferential direction of the tire as the second direction D to form a protrusion line 23. In the projection line 23, adjacent projections 30 contact each other. In particular, the second direction ends 34 of two adjacent projections 30 correspond to one another. A boundary of two protrusions 30 adjacent in the second direction D (namely, the second direction end 34) lies on the first reference surface 21.In the pattern 14, a plurality of protrusion lines 23 are provided in parallel with each other. No space is present between adjacent projection lines 23, and the projections 30 in one projection line 23 and the projections 30 in the other projection line 23 adjacent to each other contact each other.Then, the positions of the ridge lines 31 in the second direction D are shifted in the adjacent protrusion lines 23. A displacement distance is a half pitch (namely, half a pitch) in the projection line 23, at which time a pitch in the projection line 23 corresponds to a length of a projection 30 in the second direction D. The displacement distances in the second direction D are equal between all the adjacent projection lines 23. Since the protrusion lines 23 are shifted in this manner, the rib lines 31 of the protrusions 30 and the second direction ends 34 of the protrusions 30 are alternately arranged on straight lines in the first direction C as shown in FIG. 5. A plurality of lines in which the ridge lines 31 and the second direction ends 34 are alternately arranged are formed in the pattern 14.These protrusions 30 may be formed by a mold used at the time of vulcanization of the pneumatic tire 1. On the mold surface of the mold used in vulcanization, irregularities corresponding to the shapes of the protrusions 30 are formed. Such irregularities may be formed by cutting or laser machining.As described above, the protrusion 30 provided in the decorative region 11 has the rib line 31 extending in the first direction C and the slopes 32 while being inclined to the rib line 31 toward the first reference surface 21 on both sides of the rib line 31 in the second direction in the pneumatic tire 1 according to the embodiment. Here, the length of the rib line 31 is shorter than the length of the protrusion 30 in the second direction D. Then, the plurality of protrusion lines 23 are formed in which the plurality of protrusions 30 are connected in the second direction D while contacting each other, and the positions of the rib line 31 of the protrusions 30 are shifted in the second direction D in the protrusion lines 23 adjacent to each other.According to the configuration, a plurality of slopes 32 having a small area without clearance are provided, and the light is reflected on each of the slopes 32. Since the light is reflected at a plurality of slopes 32, the pattern 14 in the decorative region 11 looks luminous and three-dimensional. Accordingly, the pattern 14 becomes excellent in appearance and appearance in the decorative portion 11. When a person views the projection 30 from one of the two slopes 32 with the ridge line 31 therebetween, the one slope 32 looks glossy and the other dark. Since there are many protrusions 30 in the pattern 14, fine patterns of light and dark are seen in the pattern 14, making the pattern 14 nice. The reflection of the light on the multiple slopes 32 described above generates new optical effects.When the pneumatic tire 1 is inflated, a thin depression may be formed on the sidewall surface 10 extending in the radial direction of the tire. However, this depression is made to be non-noticeable by a plurality of projections 30 on the pattern 14 in the decorative region 11.Since such a depression is more conspicuous on the outer side in the tire radial direction than at the maximum width position of the pneumatic tire 1, the effect of making the depression conspicuous is enhanced when the decorative portion 11 is disposed on the outer side in the tire radial direction than at the maximum width position. When the decorative portion 11 is disposed at an end of the member constituting the tire, the effect that the step appearing on the surface of the sidewall surface 10 is not noticeable can be achieved by the end.The inclination angles θ of the two slopes 32 are equal with respect to a rib line 31 in the direction perpendicular to the first reference surface 21. Therefore, the gradation of light and shade can be seen similarly when a person views the pattern 14 from an arbitrary side of the two slopes 32 of the protrusion 30.Since the second direction D in the protrusion 30 is the circumferential direction of the tire, unique optical effects can be generated when the pneumatic tire 1 rotates.The first reference surface 21 is recessed to be lower than the second reference surface 22, and the protrusions 30 are provided on the first reference surface 21. However, the ridge lines 31 of the protrusions 30 are higher than the second reference surface 22, and according to the configuration, much light is applied to the portions of the protrusions 30 in the vicinity of the ridge lines 31 to generate high reflection, and the light is not sufficiently applied to the portions of the protrusions 30 in the vicinity of the first reference surface 21 to generate low reflection. Therefore, the portions of the protrusions 30 near the ridge lines 31 look bright and the portions of the protrusions 30 near the first reference surface 21 look dark, producing optical effects in which the contrast of bright and dark is emphasized.Since the heights of both ends of the ridge line 31 in the protrusion 30 are not equal from the first reference surface 21 according to the present invention, a mold for forming the protrusions 30 can be easily manufactured.When the opening angle of the two slopes 32 of the protrusion 30 is 30 degrees or more, the irregularities for forming the protrusions 30 in the mold used at the time of vulcanization are not too deep. Accordingly, the air flow in the irregularities in the mold at the time of vulcanization is good. Therefore, occurrence of air entrapment is reduced and defects are hardly caused in the pneumatic tire 1. When the opening angle of the two slopes 32 of the protrusion 30 is 90 degrees or more, the above-mentioned effects become more remarkable. When the opening angle of the two slopes 32 is 150 degrees or less, the height of the protrusions 30 is secured to some extent. Therefore, the effects obtained by the presence of the protrusions 30 become more remarkable.<Change Example 1>The directions of arrangement of the protrusions 30 are not limited to the directions of the embodiment. For example, the first direction C that is an extending direction of the rib line 31 may be the circumferential direction of the tire, and the second direction D that is orthogonal to the first direction C may be the radial direction of the tire. When the protrusions 30 are arranged such that the first direction C is the circumferential direction of the tire, the appearance of the pattern 14 changes as compared with the above embodiment.Moreover, within the pattern 14, a region where the protrusions 30 where the first direction C is the tire radial direction and a region where the protrusions 30 where the first direction C is the tire circumferential direction are combined may be formed. In addition, the protrusions 30 in which the first direction C is the radial direction of the tire and the protrusions 30 in which the first direction C is the circumferential direction of the tire are mixed in the pattern 14.< Modification Example 2>As shown in FIG. 6, the heights of the both ends 131 a, 131 bof the rib line 131 deviate from each other in a protrusion 130 from the first reference surface 21. Such a protrusion 130 may preferably be disposed such that the first direction C, which is an extending direction of the rib line 131, is set to the radial direction of the tire. In the preferred arrangement, it does not matter whether the upper end 131a or the lower end 131b is disposed on an inner side in the radial direction of the tire or on an outer side in the radial direction of the tire.The inclination angles of the two slopes 132 on both sides of the rib line 131 are equal with respect to the direction perpendicular to the first reference surface 21. In the case of FIG. 6, the opening angle of the two slopes 132 of the protrusion 130 at the upper end 131 aand at the lower end 131 bdiffers. The opening angle at which the upper end 131 ais an apex is larger than the opening angle at which the lower end 131 bis an apex. As specific numerical values, the opening angle at which the upper end 131 ais the apex is preferably 40 to 160 degrees, and the opening angle at which the lower end 131 bis the apex is preferably 30 to 150 degrees.Conversely, the opening angle at which the upper end 131 ais the apex may be smaller than the opening angle at which the lower end 131 bis the apex. It is also preferable that the opening angle at which the higher end 131 ais the apex and the opening angle at which the lower end 131 bis the apex are the same.When the heights of the both ends 131 a, 131 bof the rib line 131 are different from the first reference surface 21 as described in this modification example, the pattern 14 becomes fine, which is different from the case where the heights of the both ends of the rib line 31 are the same from the first reference surface 21 and is useful for understanding the invention.< Example 3>As shown in FIG. 7, the ridge lines 31 located at the highest position of the protrusions 30 may be deeper than the second reference surface 22 when the first reference surface 21 is recessed from the second reference surface 22. The protrusions 30 are protected by the second reference surface 22 in this modification example, which can prevent damage to the protrusions 30.< Example 4>As shown in FIG. 8, it is preferable that the first reference surface 21 protrudes from and around the second reference surface 22, and the protrusions 30 are provided on the first reference surface 21. In this modification example, the light is applied to the slopes 32 of the protrusions 30, so that the protrusions 30 are more bright.< Example 5>The pattern provided in the decorative region 11 is not limited to the pattern shown in FIG. 2. It is also preferable that marks (for example, formed of letters, symbols, or numbers) and the like are provided instead of the pattern 14, and the plurality of protrusions 30 may be provided within a contour of the mark or the like.It is preferable that no protrusion 30 is provided inside the contour 17 of the pattern 14 (or the contour of the mark), and that the plurality of protrusions 30 are provided outside the contour. In this case, the pattern 14 (or the mark or the like) is provided as a region in which no protrusion 30 is provided within the region in which the plurality of protrusions 30 are provided.< Example 6>The distance of the displacement to the second direction D in adjacent projection lines 23 is not limited to half the pitch of the projection line 23, but may be a 2 / 3 pitch or the like. Preferably, the distances of displacement are the same in all adjacent projection lines 23.< Example 7>It is not always necessary that the inclination angles θ of the two slopes 32 of a protrusion 30 are equal with respect to the first reference surface 21.[List of Reference Numerals]C center line 1 pneumatic tire 2 carcass ply 2 aturned part 2 bcoiled end 3 rubber chafer 4 belt 5 belt reinforcing layer 6 tread rubber 7 sidewall rubber 8 rim rim 9 bead part 10 sidewall surface 11 decorative portion 12 inner diameter side line 13 outer diameter side line 14 pattern 15 label 16 letter 17 contour 21 first reference surface 22 second reference surface 23 protrusion line 30 protrusion 31 rib line 32 slope 33 lateral surface 34 end of second direction 35 cut line 36 cut line 130 protrusion 131 rib line 131 aend 131 bend 132 slope

Claims

A pneumatic tire, comprising: a decorative portion (11) on a sidewall surface (10); and a first reference surface (21) and a plurality of protrusions (130) protruding from the first reference surface (21) on the decorative portion (11), wherein each of the protrusions (130) includes a rib line (131) extending in a first direction and slopes (132), wherein the slopes (132) extend from the rib line (131) to the first reference surface (21) on both sides in a second direction, and wherein the rib line (131) is interposed therebetween while the slopes (132) are inclined with respect to the first reference surface (21), wherein a length of the rib line (131) is shorter than a length of the protrusion (130) in the second direction, wherein a plurality of protrusion lines (23) are formed, wherein the plurality of protrusions (130) are connected while contacting each other in the second direction, positions of the protrusions (130) in the second direction are shifted adjacent to each other in the protrusion lines (23), and heights of both ends of the rib line (131) are different from the first reference surface (21).The pneumatic tire according to claim 1, wherein the inclination angles of the two slopes (132) with respect to a rib line (131) are equal in a direction perpendicular to the first reference surface (21).The pneumatic tire according to claim 1 or 2, wherein the second direction is a circumferential direction of the tire.The pneumatic tire according to any one of claims 1 or 2, wherein the second direction is a radial direction of the tire.The pneumatic tire according to any one of claims 1 to 4, wherein the first reference surface (21) is recessed to be lower than the second reference surface (22) around it, and wherein the rib line (131) is higher than the second reference surface (22).

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