Pneumatic tire

Abstract

To provide a pneumatic tire suppressing unintended exposure of colored rubber on the side surface of a projection part forming a mark display part.SOLUTION: A pneumatic tire comprises a bead 10, a sidewall 20, and a tread 30, wherein the sidewall 20 is provided with a mark display part 22A including a projection part projecting outward in the tire axial direction from a profile line 24 of the sidewall 20 in the tire meridional plane G, the mark display part 22A is provided with a colored rubber 22b and a colored rubber 22a in which at least a part covered by the cover rubber 22b is exposed on the surface corresponding to the colored rubber 22a. The mark display part 22A is further provided with a recess in the cross-sectional view of the tire meridional plane G and the recess bottom of the recess is arranged outside the profile line 24 of the sidewall 20 in the tire axial direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] It is known that in order to improve the appearance of pneumatic tires, the emblem display portion displayed on the sidewall portion is displayed by colored rubber. The colored rubber is vulcanized and molded onto the sidewall portion with the surface covered by a thin cover rubber, and then the cover rubber in the portion corresponding to the emblem display portion is ground off to expose the colored rubber on the surface of the sidewall portion. (Patent Document 1) [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-103849 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been an increasing demand for markings on pneumatic tires with small tire section heights. In pneumatic tires with small tire section heights, the length of the markings in the tire radial direction is short, and the size of the markings is small. When the size of the marking portion of a pneumatic tire becomes smaller, the cover rubber that covers the colored rubber on the side of the protruding portion that forms the marking portion after the tire is vulcanized and molded may be torn, exposing the colored rubber in unintended places and degrading the design of the marking portion.

[0005] The present invention has been made in consideration of the above circumstances, and has an object to provide a pneumatic tire that suppresses unintended exposure of the colored rubber on the side surface of the protruding portion that forms the emblem display portion. [Means for solving the problem]

[0006] The pneumatic tire of the present invention is a pneumatic tire comprising a pair of beads each having a bead core, a pair of sidewalls each extending radially outward from the pair of beads, and a tread disposed between the pair of sidewalls, wherein the sidewalls have a marking portion including a plurality of protrusions protruding axially outward from a profile line of the sidewall in a cross-sectional view of the tire meridian plane, the marking portion comprises a cover rubber and a colored rubber, at least a portion of which is covered by the cover rubber and exposed on the surface corresponding to the marking portion, and the marking portion further comprises a recess in a cross-sectional view of the tire meridian plane, and a bottom of the recess is disposed axially outward of the profile line of the sidewall. Effect of the Invention

[0007] According to the present invention, it is possible to provide a pneumatic tire that suppresses unintended exposure of the colored rubber on the side surface of the protruding portion that forms the emblem display portion. [Brief description of the drawings]

[0008] [Figure 1] 1 is a view showing a half cross section of a tire according to a first embodiment of the present invention in the tire axial direction (tire meridian plane). [Diagram 2] FIG. 2 is an enlarged cross-sectional view of a sidewall of the tire according to the first embodiment. [Figure 3A] 1. FIG. 2 is a view seen from the direction E in FIG. 1, showing the periphery of the emblem display portion. [Figure 3B] FIG. 2 is a view seen from the direction E in FIG. 1, showing the minimum rectangle that circumscribes the outline of the mark display portion. [Figure 4A] 1, showing the periphery of another example of the mark display portion. FIG. [Figure 4B] 4B is a view seen from the direction of the arrow E in FIG. 1, showing the minimum rectangle that circumscribes the outline of the mark display portion in FIG. 4A. [Diagram 5] FIG. 6 is an enlarged cross-sectional view of a sidewall of a tire according to a second embodiment. [Figure 6A] 5. FIG. 6 is a view taken along the arrow E in FIG. 5, showing the periphery of the emblem display portion. [Figure 6B] 5. This is a view seen from the direction E in FIG. 5, and shows the minimum rectangle that circumscribes the outer edge of the emblem display portion. [Figure 7A] 5, showing the periphery of another example of the mark display portion. FIG. [Figure 7B] 7B is a view seen from the direction of the arrow E in FIG. 5, and shows the minimum rectangle circumscribing the outer edge of the emblem display portion in FIG. 7A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (First embodiment) Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 is a diagram showing a cross section in the tire axial direction (tire meridian plane) of a tire 1 which is a pneumatic tire according to a first embodiment of the present invention. FIG. 2 is a diagram showing an enlarged cross section of a sidewall in the tire 1 according to the embodiment. FIG. 3A is an arrow view seen from the E direction in FIG. 1, showing the periphery of the emblem display part. FIG. 3B is an arrow view seen from the E direction in FIG. 1, showing the minimum rectangle circumscribing the outline of the emblem display part. FIG. 4A is an arrow view seen from the E direction in FIG. 1, showing the periphery of another example of the emblem display part. FIG. 4B is an arrow view seen from the E direction in FIG. 1, showing the minimum rectangle circumscribing the outline of the emblem display part in FIG. 4A.

[0010] The cross-sectional view of FIG. 1 is a cross-sectional view in the axial direction of a tire (cross-sectional view of the tire meridian) in an unloaded state in which a tire 1 is mounted on a regular rim (not shown) and inflated to a regular internal pressure. The regular rim is a rim that is determined for each tire by a standard system including the standard on which the tire is based, for example, a standard rim for JATMA, and a "Measuring Rim" for TRA and ETRTO. The regular internal pressure is an air pressure that is determined for each tire by each standard in a standard system including the standard on which the tire is based, and in the case of tires for trucks and buses and tires for light trucks, it is the maximum air pressure for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "INFLATION PRESSURE" for ETRTO. For tires for passenger cars, it is usually 180 kPa, but for tires marked "Extra Load" or "Reinforced", it is 220 kPa.

[0011] The basic structure of the tire 1 is symmetrical in a cross section in the tire axial direction (tire meridian plane). Fig. 1 shows a half cross section of the right half of the tire 1, and the left half (not shown) has the same structure. In Fig. 1, the symbol S1 indicates the tire equatorial plane. The tire equatorial plane S1 is a plane that is perpendicular to the tire rotation axis (tire meridian) and is located at the center in the tire axial direction.

[0012] Here, the tire axial direction is a direction parallel to the tire rotation axis, and is the left-right direction on the paper in Fig. 1. In Fig. 1, this is illustrated as the tire axial direction X. The tire axially inner side is a direction approaching the tire equatorial plane S1, and is the left side on the paper in Fig. 1. The tire axially outer side is a direction away from the tire equatorial plane S1, and is the right side on the paper in Fig. 1.

[0013] The tire radial direction is a direction perpendicular to the tire rotation axis, and is the up-down direction on the paper in Fig. 1. In Fig. 1, this is illustrated as tire radial direction Y. The outer side in the tire radial direction is a direction away from the tire rotation axis, and is the upper side on the paper in Fig. 1. The inner side in the tire radial direction is a direction approaching the tire rotation axis, and is the lower side on the paper in Fig. 1.

[0014] In addition, the tire circumferential direction is the direction of the arc line Z in FIG. 3A, and the arc line Z is an arc line centered on the tire rotation axis.

[0015] As shown in FIG. 1, the tire 1 includes a pair of beads 10, a pair of sidewalls 20 extending radially outward from each of the pair of beads 10, a tread 30 disposed between the pair of sidewalls 20, a carcass ply 60 disposed spanning between the pair of beads 10, and an inner liner 70 disposed on the tire cavity side of the carcass ply 60.

[0016] The pair of beads 10 are disposed on both axial ends of the tire and on the inner ends in the tire radial direction. The bead 10 includes a bead core 11, a bead filler 12 extending from the bead core 11 to the outer side in the tire radial direction, a chafer 13, and a rim strip rubber 14.

[0017] The bead core 11 is an annular member in which a rubber-coated metal bead wire is wound multiple times in the circumferential direction of the tire. The bead core 11 is a member that serves to fix the tire 1 filled with air to the rim.

[0018] The bead filler 12 has a tapered shape in which the thickness decreases as it extends from the inner side in the tire radial direction to the outer side in the tire radial direction. The bead filler 12 is provided to increase the rigidity of the peripheral portion of the bead 10 and ensure high maneuverability and stability. The bead filler 12 is made of, for example, rubber having a higher hardness than the surrounding rubber members. The inner surface of the bead filler 12 in the tire radial direction is joined to the outer surface of the bead core 11 in the tire radial direction.

[0019] The chafer 13 further surrounds the outside of the carcass ply 60 which surrounds the bead core 11 and the bead filler 12 .

[0020] The rim strip rubber 14 is disposed axially outward of the chafer 13 and the carcass ply 60. The rim strip rubber 14 is a member that comes into contact with a rim on which the tire 1 is mounted.

[0021] The sidewall 20 includes a sidewall rubber 21 disposed axially outward of the carcass ply 60, and a marking display portion 22A. The sidewall rubber 21 and the marking display portion 22A form the outer wall surface of the tire 1. The sidewall 20 is the portion that bends the most when the tire 1 performs its cushioning function. For this reason, the sidewall rubber 21 of the sidewall 20 is usually made of flexible rubber having fatigue resistance. The details of the mark display section 22A will be described later.

[0022] The tread 30 includes an endless belt 31 , a cap ply 32 , and a tread rubber 33 .

[0023] The belt 31 is disposed on the outer side in the tire radial direction of the carcass ply 60. The cap ply 32 is disposed on the outer side in the tire radial direction of the belt 31.

[0024] The belt 31 is a member that reinforces the tread 30. The belt 31 of this embodiment has a two-layer structure including an outer belt 311 and an inner belt 312. Both the outer belt 311 and the inner belt 312 have a structure in which a plurality of cords such as steel cords are covered with rubber. Note that the belt 31 is not limited to a two-layer structure, and may have a one-layer structure or a three-layer or more structure.

[0025] The cap ply 32 is a member that reinforces the tread 30 together with the belt 31. The cap ply 32 has a structure in which a plurality of insulating organic fiber cords, such as polyamide fiber, are covered with rubber. By providing the cap ply 32, it is possible to improve durability and reduce road noise during driving.

[0026] The tread rubber 33 is disposed on the outer side in the tire radial direction of the cap ply 32. The tread rubber 33 is a member that constitutes a tread surface 34 that is the outer surface of the tread 30.

[0027] The carcass ply 60 constitutes a ply that forms the framework of the tire 1. The carcass ply 60 is embedded in the tire 1 in a manner that passes between a pair of beads 10, through a pair of sidewalls 20 and the tread 30. The carcass ply 60 includes a plurality of carcass cords (not shown) that form the framework of the tire 1. The plurality of carcass cords extend, for example, in the axial direction of the tire, and are arranged side by side in the circumferential direction of the tire. The carcass cords are made of insulating organic fiber cords such as polyester or polyamide. The plurality of carcass cords are covered with rubber to form the carcass ply 60.

[0028] The carcass ply 60 has a ply body portion 601 extending from one bead core 11 to the other bead core 11 and extending between the tread 30 and the bead 10, a pair of bend portions 602 folded back from the ply body portion 601 at the bead core 11, and a pair of turn-up portions 603 extending outward in the tire radial direction from each of the bend portions 602. The ply body portion 601, the bend portions 602, and the turn-up portions 603 surround the bead fillers 12 and the bead cores 11. The turn-up portions 603 in the portion on the outer side of the bead fillers 12 in the tire radial direction are overlapped with the ply body portion 601.

[0029] Although the carcass ply 60 in the embodiment has a two-layer structure, the carcass ply 60 is not limited to a two-layer structure, and may have a one-layer structure, or a three-layer or more structure.

[0030] The chafer 13 of the bead 10 described above is provided so as to surround the radially inner end of the carcass ply 60 including the bent portion 602. The rim strip rubber 14 is disposed axially outward of the chafer 13 and the folded-up portion 603 of the carcass ply 60. The radially outer end of the rim strip rubber 14 is covered with the sidewall rubber 21 described above.

[0031] The inner liner 70 covers the inner surface of the ply body portion 601 of the carcass ply 60 and the inner surface of the chafer 13 of the pair of beads 10. The inner liner 70 is made of air-permeable rubber and prevents air in the tire cavity from leaking to the outside. The inner surface of the inner liner 70 forms the tire inner surface 701 between the pair of beads 10. The inner liner 70 of the tire 1 of this embodiment is made up of two layers, an inner inner liner 702 and an outer inner liner 703.

[0032] FIG. 1 shows a cross section in the tire axial direction (tire meridian plane) of a tire 1 which is a pneumatic tire according to an embodiment. As shown in FIG. 1, the sidewall 20 has a sidewall rubber 21 and a marking portion 22A. The marking display portion 22A has a colored rubber 22a and a cover rubber 22b. The colored rubber 22a is disposed on the axially outer side of the carcass ply 60. The colored rubber 22a is provided on the sidewall 20 in an annular shape.

[0033] FIG. 2 is an enlarged cross-sectional view of a sidewall of the tire 1. As shown in FIG. 2, the cover rubber 22b is disposed on the tire outer surface side of the color rubber 22a. Also, the cover rubber 22b is disposed so as to cover the color rubber 22a.

[0034] The mark display portion 22A is formed on a part of the sidewall 20 of the tire 1 in the tire circumferential direction so as to protrude axially outward from the profile line 24 of the sidewall 20 when the tire 1 is vulcanized. After the tire 1 is vulcanized, the cover rubber 22b of the part corresponding to the part F visually recognized as the mark is ground and removed to expose the colored rubber 22a. As a result, the part F visually recognized as the mark of the mark display portion 22A is exposed on the surface of the sidewall 20.

[0035] As shown in Fig. 2, the emblem display portion 22A has a groove 23 as a recess in a cross-sectional view of the tire meridian plane. A mold for vulcanizing and molding the tire 1 has a recess for forming the emblem display portion 22A. A protrusion disposed in a part of the recess of the mold forms the groove 23 in a cross-sectional view of the tire meridian plane of the emblem display portion 22A during vulcanization and molding of the tire 1. The tire meridian plane is selected so that the groove width (A) mm of the groove 23 described below is the maximum groove width in the tire circumferential direction of the emblem display portion 22A. The groove 23 has a recessed shape in a cross-sectional view of the tire meridian plane, and extends and opens in one direction in a front view of the emblem display portion 22A.

[0036] As shown in Fig. 2, the groove width (A) mm of the groove 23 as the recess width (A) mm of the recess is defined by the distance between the surfaces of the cover rubber 22b facing at the groove upper end of the groove 23 after the color rubber 22a corresponding to the symbol display portion 22A is exposed. The groove depth (B) mm of the groove 23 as the recess depth (B) mm of the recess is defined by the distance from the groove upper end of the groove 23 to the groove bottom as the recess bottom.

[0037] The cover rubber 22b is disposed on the surface of the groove 23. That is, the cover rubber 22b is pressed by the raised portion disposed in the mold during vulcanization molding of the tire 1. At this time, the groove 23 is formed along the shape of the raised portion disposed in the mold. It is assumed that a strong tensile force is applied to the cover rubber 22b pressed by the thin raised portion disposed in the mold during vulcanization molding of the tire 1, and therefore it is considered that the cover rubber 22b will break in the vicinity of the marking display portion 22A. In recent years, the marking display portion 22A is increasingly being displayed on pneumatic tires with small tire cross-sectional heights. In pneumatic tires with small tire cross-sectional heights, the length of the marking display portion 22A in the tire radial direction is short. The marking display portion 22A with a short length in the tire radial direction is molded using a mold having a thin protruding portion, so it is necessary to suppress the occurrence of tearing of the cover rubber 22b in the vicinity of the marking display portion 22A.

[0038] 3A is an arrow view of the tire 1 according to the embodiment seen from the E direction, and is a diagram showing an example of the mark display portion 22A. In FIG. 3A, the alphabet letter "E" is illustrated as an example of the portion F in the mark display portion 22A that is visually recognized as a mark. In the arrow view of FIG. 1 seen from the E direction, which is a side view of the tire 1, the portion F in the mark display portion 22A that is visually recognized as a mark is formed by the color rubber 22a corresponding to the mark display including letters, figures, and symbols protruding from the surface of the sidewall 20, and the outer frame 26 made of the cover rubber 22b arranged to surround the outer periphery of the color rubber 22a. The outline of the portion F in the mark display portion 22A that is visually recognized as a mark is the exposed surface of the color rubber 22a at a protruding height (C) described later in the tire axial direction, and is formed by the outer periphery of the outer frame 26 made of the cover rubber 22b arranged to surround the outer periphery of the color rubber 22a. 1 is a side view of the tire 1, ie, a front view of the marking display portion 22A.

[0039] For example, as shown in Fig. 3A, when the letter "E" of the alphabet is arranged as the emblem display portion 22A with the lower side of the letter facing the tire rotation axis and the upper side of the letter facing outward in the tire radial direction, three horizontal lines constituting the letter "E" protrude as three protrusions outward in the tire axial direction from the profile line 24 of the sidewall 20 in a cross-sectional view of the tire meridian plane G. Also, two grooves 23 are provided between each of the three protrusions protruding outward in the tire axial direction in a cross-sectional view of the tire meridian plane G. In other words, the emblem display portion 22A has grooves 23 as recesses between a plurality of protrusions in a cross-sectional view of the tire meridian plane G.

[0040] FIG. 4A is an arrow view of the tire 1 according to the embodiment as seen from the E direction, and is a diagram showing an example of another mark display portion 22A. In FIG. 4A, the letter "O" of the alphabet is illustrated as an example of the portion F that is visually recognized as a mark in the mark display portion 22A. For example, as shown in FIG. 4A, when the letter "O" of the alphabet is arranged as the mark display portion 22A with the lower side of the letter facing the tire rotation axis and the upper side of the letter facing the tire radial direction outer side, in a cross-sectional view of the tire meridian plane G, two horizontal lines constituting the letter "O" will protrude as two protruding parts outward in the tire axial direction from the profile line 24 of the sidewall 20. In addition, in a cross-sectional view of the tire meridian plane G, a depression 25 as a recess that is arranged to be surrounded by a plurality of protruding parts protruding outward in the tire axial direction is provided. In this case, the recess width (A) as the recess width (A) of the recess corresponds to the groove width (A), the recess depth (B) as the recess depth (B) of the recess corresponds to the groove depth (B), and the recess bottom as the recess bottom corresponds to the groove bottom.

[0041] Here, the area (D) of the mark display portion is formed by the outline of the portion F of the mark display portion 22A that is visually recognized as the mark. Note that, in the case of a mark such as the alphabet letter "O" that has a depression 25 arranged so as to be surrounded by multiple protrusions, the area (D) of the mark display portion is the area excluding the area of ​​the depression 25 on the exposed surface of the color rubber 22a when viewed from the front of the mark display portion 22A.

[0042] As shown in Fig. 3B, the mark display portion 22A has a minimum rectangular area (E) that is a rectangle circumscribing the outline of the portion F of the mark display portion 22A that is visually recognized as a mark, and is formed so that its area is the smallest. Fig. 3B is an example of the mark display portion 22A of the alphabet letter "E". As shown in Fig. 4B, the mark display portion 22A has a minimum rectangular area (E) that is a rectangle circumscribing the outline of the portion F that is visually recognized as a mark in the mark display portion 22A and is formed so that its area is the smallest. Fig. 4B is an example of the mark display portion 22A of the alphabet letter "O".

[0043] In this embodiment, in order to prevent a strong pulling force from being applied to the cover rubber 22b on the surface of the groove 23, the groove bottom as the bottom of the recess is disposed axially outward of the profile line 24 of the sidewall 20. As a result, the groove 23 is formed by a mold having a gently shaped protuberance. Therefore, it is possible to suitably prevent the tearing of the cover rubber 22b covering the colored rubber 22a in the groove 23, which is the side surface of the protruding portion forming the mark display portion 22A after the tire 1 is vulcanized. Therefore, it is possible to prevent the colored rubber 22a from being unintentionally exposed in the mark display portion 22A.

[0044] In this embodiment, in a front view of the mark display portion 22A, which is a tire side view, the relationship between the mark display portion area (D) formed by the outline of the mark display portion 22A and the minimum rectangle area (E) that is a rectangle circumscribing the outline of the mark display portion 22A and is formed so that the area is the smallest is preferably mark display portion area (D)÷minimum rectangle area (E)≧70%. This allows the tire 1 to more effectively prevent unintended exposure of the colored rubber 22a in the grooves 23 that are the side surfaces of the protruding portions of the mark display portion 22A.

[0045] In addition, in this embodiment, in order to more effectively prevent unintended exposure of the colored rubber 22a, the length of the recess depth (B) of the recess in the marking display portion 22A is preferably 80% or less of the protrusion height (C), and more preferably 50% or more and 80% or less. EXAMPLES

[0046] Examples will be described below. As shown in Table 1, tires of Examples 1 to 8 were manufactured having the same configuration as tire 1 of the above-mentioned embodiment having the marking display portion 22A, and in which the groove bottom of groove 23 as the bottom of the recess was positioned axially outboard of profile line 24 of sidewall 20. Also, tires of Comparative Examples 1 to 4 were manufactured in which the groove bottom of groove 23 as the bottom of the recess was positioned on profile line 24 of sidewall 20.

[0047] In each of the examples and comparative examples, the protruding height (C) of the emblem display portion 22A was set to 1.5 mm. In the examples 1 to 4, the raised amount of the emblem display portion 22A was set to 0.3 mm. In the examples 5 to 8, the raised amount of the emblem display portion 22A was set to 0.7 mm. The raised amount is defined as the distance from the profile line 24 of the sidewall 20 to the groove bottom of the groove 23 of the emblem display portion 22A. That is, the recess depth (B) mm of the emblem display portion 22A in the examples 1 to 4 was 1.2 mm, and the recess depth (B) mm of the emblem display portion 22A in the examples 5 to 8 was 0.8 mm. In the examples 1 to 4, the raised amount ratio of the emblem display portion 22A was set to 20%. In the examples 5 to 8, the raised amount ratio of the emblem display portion 22A was set to 47%. The raising ratio is the ratio of the raising amount to the protruding height (C) of the emblem display portion 22A. That is, the recess depth (B) of the recess in the emblem display portion 22A of Examples 1 to 4 is 80% of the protruding height (C). Also, the recess depth (B) of the recess in the emblem display portion 22A of Examples 5 to 8 is 53% of the protruding height (C).

[0048] In addition, in the following (Formula 1) showing the relationship between the area (D) of the mark display portion formed by the outline of the mark display portion 22A and the area (E) of the minimum rectangle circumscribing the outline of the mark display portion 22A and formed so that the area is the smallest, alphabet characters with a value of Y in the range of 75.9% to 83.4% were used. Each tire produced was evaluated for whether or not the cover rubber 22b had been torn. If there was almost no tear in the cover rubber 22b and no unintended exposure of the colored rubber 22a was confirmed, the evaluation result was "◯", if there was a tear but the exposure of the colored rubber 22a from the tear was not noticeable, the evaluation result was "△", and if there was a tear and the exposure of the colored rubber 22a was noticeable, the evaluation result was "X". More specifically, when the ratio of the exposed length to the protruding height (C) is less than 10%, the evaluation result is "◯", when the ratio of the exposed length to the protruding height (C) is 10% to 30%, the evaluation result is "△", and when the ratio of the exposed length to the protruding height (C) is more than 30%, the evaluation result is "◯". The exposed length is the length of the color rubber 22a exposed from the tear in the cover rubber 22b. Mark display area (D) ÷ minimum rectangular area (E) = Y% (Formula 1)

[0049] [Table 1]

[0050] As shown in Table 1, in Comparative Examples 1 to 4 in which the groove bottom of the groove 23 as the recess bottom is positioned on the profile line 24 of the sidewall 20, tears occurred in the cover rubber 22b and the exposure of the color rubber 22a was noticeable. On the other hand, in Examples 1 to 4 in which the raised amount ratio is 20%, tears occurred but the exposure of the color rubber 22a was not noticeable. In Examples 5 to 8 in which the raised amount ratio is 47%, there was almost no tearing of the cover rubber 22b and no unintended exposure of the color rubber 22a was confirmed.

[0051] From the results in Table 1, it was confirmed that by locating the groove bottom of the groove 23 as the bottom of the recess axially outward of the profile line 24 of the sidewall 20, it is possible to suitably suppress the breakage of the cover rubber 22b covering the colored rubber 22a in the marking display portion 22A after the tire 1 is vulcanized and molded. Therefore, it is possible to suppress unintended exposure of the colored rubber 22a in the marking display portion 22A. From the results of Examples 5 to 8, it was confirmed that when the recess depth (B) of the recess in the marking display portion 22A is 53% of the protruding height (C), the exposed length can be suppressed to less than 0.1 mm.

[0052] The value of Y in (Equation 1) is preferably 70% or more. This makes it possible to more suitably prevent breakage of the cover rubber 22b covering the colored rubber 22a in the marking display portion 22A after the tire 1 is vulcanized. The value of Y in (Equation 1) may be 75% or more and 85% or less. Even with such a tire 1, it is possible to suitably prevent breakage of the cover rubber 22b covering the colored rubber 22a in the marking display portion 22A after the tire 1 is vulcanized.

[0053] The thickness of the cover rubber 22b is preferably 0.08 mm or more and 0.20 mm or less. In the condition of (Formula 2), if the cover rubber 22b is, for example, 0.08 mm or more and 0.20 mm or less, even if the cover rubber 22b is pressed against the protruding portion of the mold, breakage due to a tensile force generated in the cover rubber 22b can be suitably suppressed.

[0054] In order to prevent the cover rubber 22b from breaking due to the tensile force, it is possible to make the groove bottom shallower. However, if the distance between the groove bottom and the exposed surface of the colored rubber 22a corresponding to the emblem display portion 22A is short, the visibility of the outline of the emblem display portion 22A will be poor, and the design will be deteriorated. Therefore, considering the relationship between the prevention of breakage due to the tensile force and the design, it is preferable that the groove depth (B) is 50% or more of the protruding height (C) of the emblem display portion 22A (FIG. 2), which is the distance between the profile line 24 of the sidewall 20 and the exposed surface of the colored rubber 22a. This allows the outline of the emblem display portion 22A to be clearly visible, improving the design, while preventing unintended exposure of the colored rubber 22a due to tearing of the cover rubber 22b.

[0055] If the protruding height (C) of the emblem display portion 22A protrudes too far from the profile line 24 of the sidewall 20, it will not look good, and the distance between the depression and the protrusion of the mold will be large, which will increase the tensile force generated in the cover rubber 22b and increase the possibility of tearing. Also, if the protruding amount is extremely small, it will be difficult to see the outline of the emblem display portion 22A clearly, so the protruding height (C) of the emblem display portion 22A is preferably 1 mm or more and 3 mm or less.

[0056] The marking display portion 22A is increasingly being displayed on pneumatic tires with a small tire cross-sectional height. In pneumatic tires with a small tire cross-sectional height, the length of the marking display portion 22A in the tire radial direction is short, and the size of the marking display portion 22A is also small. In this case, if the length of the marking display portion 22A in the tire radial direction is too small, the design is deteriorated. Therefore, it is preferable that the length of the marking display portion 22A in the tire radial direction is 15 mm or more and 25 mm or less when viewed from the front of the marking display portion 22A.

[0057] When the length of the marking display portion 22A in the tire radial direction in a front view of the marking display portion 22A is 15 mm or more and 25 mm or less, the tire cross-sectional height is preferably 155 mm or less. More preferably, the tire cross-sectional height is 130 mm or less.

[0058] The tire 1 according to the first embodiment described above provides the following advantages.

[0059] (1) The tire 1 according to the first embodiment is a pneumatic tire including a pair of beads 10 each having a bead core 11, a pair of sidewalls 20 each extending radially outward from each of the pair of beads 10, and a tread 30 disposed between the pair of sidewalls 20, wherein the sidewalls 20 are provided with a marking display portion 22A including a protrusion that protrudes axially outward from a profile line 24 of the sidewalls 20 in a cross-sectional view of the tire meridian plane G, the marking display portion 22A is provided with a cover rubber 22b and a colored rubber 22a, at least a portion of which is covered by the cover rubber 22b and exposed on the surface, and the marking display portion 22A has a recess in a cross-sectional view of the tire meridian plane G, and the bottom of the recess is disposed axially outward from the profile line 24 of the sidewalls 20.

[0060] This makes it possible to prevent the color rubber 22a from being unintentionally exposed at the mark display portion 22A.

[0061] (2) In the tire 1 described in (1), in a front view of the marking portion 22A, which is a side view of the tire, the relationship between the marking portion area (D) formed by the contour of the marking portion 22A and the minimum rectangle area (E) that is a rectangle circumscribing the contour of the marking portion 22A and is formed so that its area is the smallest is marking portion area (D) ÷ minimum rectangle area (E) ≧ 70%.

[0062] This makes it possible for the tire 1 to more effectively prevent unintended exposure of the colored rubber 22a at the marking portion 22A.

[0063] (3) In the tire (1) described in (1) or (2), the cover rubber (22b) has a thickness of 0.08 mm or more and 0.20 mm or less.

[0064] This makes it possible to more effectively prevent unintended exposure of the colored rubber 22a at the mark display portion 22A of the tire 1. Also, in the mark display portion 22A, the exposed portion of the colored rubber 22a can be seen sufficiently widely compared to the thickness of the cover rubber 22b, thereby improving the design of the mark display portion 22A.

[0065] (4) In the tire 1 described in (1) to (3), the recess depth (B) of the recess is 80% or less of the protruding height of the marking portion protruding from the profile line 24 of the sidewall 20.

[0066] This makes it possible for the tire 1 to more effectively prevent unintended exposure of the colored rubber 22a at the marking portion 22A.

[0067] In the tire 1 described in (5)(4), the recess depth (B) of the recess is 50% or more of the protruding height (C) of the marking portion 22A protruding from the profile line 24 of the sidewall 20.

[0068] This makes it possible to ensure the design by making the outline of the emblem display portion 22A look neat, while preventing the colored rubber 22a from being unintentionally exposed due to the tearing of the cover rubber 22b. Also, in the emblem display portion 22A, the exposed portion of the colored rubber 22a can be seen sufficiently widely compared to the thickness of the cover rubber 22b, improving the design of the emblem display portion 22A.

[0069] (6) In the tire 1 described in (1) to (5), the protruding height (C) of the marking portion 22A protruding from the profile line 24 of the sidewall 20 is 1.0 mm or more and 3.0 mm or less.

[0070] This reduces the tensile force generated in the cover rubber 22b of the tire 1, lowering the possibility of tearing, and also improves the design by clearly defining the light and dark of the surface of the colored rubber 22a of the emblem display portion 22A and the profile line 24.

[0071] (7) In the tire 1 described in (1) to (6), the length of the marking display portion 22A in the tire radial direction is 15 mm or more and 25 mm or less.

[0072] In such a tire 1 as well, unintended exposure of the colored rubber 22a can be suppressed while ensuring the design.

[0073] (8) In the tire 1 according to any one of (1) to (7), the tire section height is 155 mm or less.

[0074] In such a tire 1 as well, unintended exposure of the colored rubber 22a can be suppressed while ensuring the design.

[0075] (9) In the tire 1 described in (1) to (8), the tire section height is 130 mm or less.

[0076] In such a tire 1 as well, unintended exposure of the colored rubber 22a can be suppressed while ensuring the design.

[0077] (10) In the tire (1) described in (1) to (9), the recess is a groove (23).

[0078] In this type of tire 1 as well, the effects (1) to (9) are achieved.

[0079] (11) In the tire (1) described in (1) to (9), the recess is a depression (25).

[0080] In this type of tire 1 as well, the effects (1) to (9) are achieved.

[0081] Second embodiment Next, a second embodiment of the present invention will be described with reference to Figures 5 to 7B. In this second embodiment, the shape of the emblem display unit 22B according to the present invention is different from that of the emblem display unit 22A of the first embodiment, but other configurations are the same or similar. Therefore, in the following description, the same components as those in the first embodiment are given the same reference numerals, and their description is omitted or simplified, and the differences will be mainly described.

[0082] Fig. 5 is an enlarged cross-sectional view of a sidewall in a tire according to a second embodiment. Fig. 6A is an arrow view seen from the E direction in Fig. 5, showing the periphery of the emblem display part. Fig. 6B is an arrow view seen from the E direction in Fig. 5, showing the minimum rectangle circumscribing the outer edge of the emblem display part. Fig. 7A is an arrow view seen from the E direction in Fig. 5, showing the periphery of another example of the emblem display part. Fig. 7B is an arrow view seen from the E direction in Fig. 5, showing the minimum rectangle circumscribing the outer edge of the emblem display part in Fig. 7A.

[0083] As shown in FIG. 5, the emblem display portion 22B has grooves 23 as recesses of different sizes in a cross-sectional view of the tire meridian plane.

[0084] In Fig. 6A, the letter "E" is illustrated as an example of the portion F in the mark display portion 22B that is visually recognized as a mark. In the side view of the tire 1, seen from the direction of the arrow E in Fig. 5, the portion F in the mark display portion 22B that is visually recognized as a mark is formed by a colored rubber 22a that corresponds to the mark display including letters, figures, and symbols protruding from the surface of the sidewall 20, and an outer frame 26 and an inner frame 27 made of a cover rubber 22b that is arranged to surround the colored rubber 22a. The outer periphery of the portion F in the mark display portion 22B that is visually recognized as a mark forms an outer edge H of the portion F.

[0085] For example, as shown in FIG. 6A, when the letter "E" is positioned as the emblem display portion 22B with the bottom side facing toward the tire rotation axis and the top side facing radially outward in the tire, in a cross-sectional view of the tire meridian plane G, the three horizontal lines that make up the letter "E" protrude as six protrusions corresponding to the three horizontal lines axially outward from the profile line 24 of the sidewall 20. In addition, five grooves 23 as recesses are provided between each of the six protruding portions protruding axially outward in the cross section of the tire meridian plane G. In other words, the marking display portion 22B has the grooves 23 as recesses between a plurality of protruding portions in the cross section of the tire meridian plane G.

[0086] Here, in a front view of the emblem display portion 22B, of the five grooves 23, the first groove 23 from the top, the third groove 23, and the fifth groove 23 from the top are formed by opposing surfaces of the cover rubber 22b of the inner frame 27. In other words, in a front view of the emblem display portion 22B, of the five grooves 23, the first groove 23 from the top, the third groove 23, and the fifth groove 23 are present inside the outer edge H of the portion F that is visually recognized as the emblem in the emblem display portion 22B.

[0087] In addition, in a front view of the emblem display portion 22B, of the five grooves 23, the second groove 23 from the top and the fourth groove 23 are formed by the outer edges H of the portion F visually recognized as the emblem in the emblem display portion 22B. In other words, in a front view of the emblem display portion 22B, of the five grooves 23, the second groove 23 from the top and the fourth groove 23 are present outside the outer edge H of the portion F visually recognized as the emblem in the emblem display portion 22B.

[0088] Here, the area (D) of the mark display portion is formed by the inside of the outer edge H of the portion F that is visually recognized as the mark in the mark display portion 22B.

[0089] As shown in Fig. 6B, the mark display portion 22B has a minimum rectangular area (E) that is a rectangle circumscribed around an outer edge H of a portion F that is visually recognized as a mark in the mark display portion 22B and is formed so that the area of ​​the rectangle is the smallest. Fig. 6B is an example of the mark display portion 22B of the alphabet letter "E".

[0090] The groove bottom of the groove 23, which is the bottom of the recess existing outside the outer edge H of the portion F visually recognized as the mark in the mark display portion 22B, is preferably positioned outside the profile line 24 of the sidewall 20 in the tire axial direction. This makes it possible to prevent the color rubber 22a from being unintentionally exposed at the emblem display portion 22B, and also makes it possible to clearly show the outer edge H of the emblem display portion 22B.

[0091] In addition, preferably, in a front view of the marking display portion 22B, which is a side view of the tire, the relationship between the marking display portion area (D) formed by the inside of the outer edge H of the marking display portion 22B and the minimum rectangle area (E) which is a rectangle circumscribing the outer edge H of the marking display portion 22B and is formed so that its area is the smallest is marking display portion area (D) ÷ minimum rectangle area (E) ≧ 70%. This makes it possible for the tire 1 to more effectively prevent unintended exposure of the colored rubber 22a in the grooves 23 that are the protruding portions of the marking display portion 22B.

[0092] More preferably, the groove bottom of the groove 23 as the bottom of the recess existing inside the outer edge H of the portion F visually recognized as the mark in the mark display portion 22B is positioned axially outboard of the profile line 24 of the sidewall 20. This makes it possible to prevent unintended exposure of the color rubber 22a at the emblem display portion 22B. Also, the inner circumference formed by the inner frame 27 of the emblem display portion 22B can be clearly seen.

[0093] In Fig. 7A, the letter "O" is illustrated as an example of the portion F in the mark display portion 22B that is visually recognized as a mark. In the side view of the tire 1, seen from the direction of the arrow E in Fig. 5, the portion F in the mark display portion 22B that is visually recognized as a mark is formed by a colored rubber 22a corresponding to the mark display including letters, figures, and symbols protruding from the surface of the sidewall 20, and an outer frame 26 and an inner frame 27 made of a cover rubber 22b arranged to surround the colored rubber 22a. The outer periphery of the portion F in the mark display portion 22B that is visually recognized as a mark forms an outer edge H of the portion F.

[0094] For example, as shown in FIG. 7A, when the letter "O" is positioned as the emblem display portion 22B with the bottom side facing toward the tire rotation axis and the top side facing radially outward in the tire, in a cross-sectional view of the tire meridian plane G, two horizontal lines constituting the letter "O" protrude as four protrusions axially outward from the profile line 24 of the sidewall 20. In addition, in a cross-sectional view of the tire meridian plane G, one depression 25 as a recess and two grooves 23 as recesses are provided, which are arranged so as to be surrounded by multiple protrusions protruding axially outward.

[0095] Here, in a front view of the emblem display portion 22B, the two grooves 23 are formed by opposing surfaces of the cover rubber 22b of the inner frame 27. In other words, in a front view of the emblem display portion 22B, the two grooves 23 are present inside the outer edge H of the portion F that is visually recognized as the emblem in the emblem display portion 22B.

[0096] In addition, in a front view of the emblem display portion 22B, one depression is formed by the outer edges H of the portions F that are visually recognized as a mark in the emblem display portion 22B. In other words, in a front view of the emblem display portion 22B, one depression exists outside the outer edge H of the portions F that are visually recognized as a mark in the emblem display portion 22B.

[0097] Here, the area (D) of the mark display portion is formed by the inside of the outer edge H of the portion F of the mark display portion 22B that is visually recognized as a mark. Note that the area (D) of the mark display portion is the area excluding the area of ​​the recess 25 on the exposed surface of the colored rubber 22a in the front view of the mark display portion 22B, in the case of a mark such as the alphabet letter "O" that has a recess 25 arranged so as to be surrounded by multiple protrusions. In other words, the area (D) of the mark display portion is formed by the inside surrounded by the outer edge H of the portion F.

[0098] As shown in Fig. 7B, the mark display portion 22B has a minimum rectangular area (E) that is a rectangle circumscribed around an outer edge H of a portion F that is visually recognized as a mark in the mark display portion 22B and is formed so that the area of ​​the rectangle is the smallest. Fig. 7B is an example of the mark display portion 22B of the alphabet letter "O."

[0099] The bottom of the recess 25, which is the bottom of a recess that exists outside the outer edge H of the portion F that is visually recognized as a mark in the mark display portion 22B, is preferably positioned outside the profile line 24 of the sidewall 20 in the tire axial direction. This makes it possible to prevent the color rubber 22a from being unintentionally exposed at the emblem display portion 22B, and also makes it possible to clearly show the outer edge H of the emblem display portion 22B.

[0100] In addition, preferably, in a front view of the marking display portion 22B, which is a side view of the tire, the relationship between the marking display portion area (D) formed by the inside of the outer edge H of the marking display portion 22B and the minimum rectangle area (E) which is a rectangle circumscribing the outer edge H of the marking display portion 22B and is formed so that its area is the smallest is marking display portion area (D) ÷ minimum rectangle area (E) ≧ 70%. This makes it possible for the tire 1 to more effectively prevent unintended exposure of the colored rubber 22a in the grooves 23 that are the protruding portions of the marking display portion 22B.

[0101] More preferably, the groove bottom of the groove 23 as the bottom of the recess existing inside the outer edge H of the portion F visually recognized as the mark in the mark display portion 22B is positioned axially outboard of the profile line 24 of the sidewall 20. This makes it possible to prevent unintended exposure of the color rubber 22a at the emblem display portion 22B. Also, the inner circumference formed by the inner frame 27 of the emblem display portion 22B can be clearly seen.

[0102] According to the tire 1 according to the second embodiment described above, the same effects as those (1) to (8) described in the first embodiment are achieved.

[0103] Although specific embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and even if modifications and improvements are made within the scope of the present invention, they will still be included in the scope of the present invention.

[0104] The configuration according to the embodiment can be applied to pneumatic tires for passenger cars including light cars and SUVs, as well as pneumatic tires for various vehicles such as light trucks, trucks, and buses. [Explanation of symbols]

[0105] 1. Pneumatic tires 10 Beads 20 Sidewall 22 Mark display section 22a Colored Rubber 22b Cover rubber 23 Groove (dent) 24 Profile Lines 25 Depression 30 Tread A Depression width, groove width, depression width B. Dent depth, groove depth, depression depth C Projection height D Mark display area E minimum rectangular area

Claims

1. A pair of beads having bead cores; a pair of sidewalls extending radially outward from each of the pair of beads; A pneumatic tire having a tread disposed between the pair of sidewalls, the sidewall includes a marking display portion including a protruding portion protruding axially outward from a profile line of the sidewall in a cross-sectional view of a tire meridian plane, The mark display unit is Cover rubber and and a color rubber, at least a part of which is exposed on the surface and is covered by the cover rubber. The marking display portion has a recess in a cross-sectional view of the tire meridian plane, A pneumatic tire, wherein a bottom of the recess is disposed axially outboard of a profile line of the sidewall.

2. In a front view of the marking portion, which is a side view of the tire, the relationship between the marking portion area (D) formed by the outline of the marking portion and the minimum rectangular area (E) that is a rectangle circumscribing the outline of the marking portion and is formed so that the area is the smallest is as follows: Mark display area (D) ÷ minimum square area (E) ≧70% The pneumatic tire according to claim 1 .

3. The pneumatic tire according to claim 1 , wherein the cover rubber has a thickness of 0.08 mm or more and 0.20 mm or less.

4. 2. The pneumatic tire according to claim 1, wherein a recess depth (B) of the recess is 80% or less of a protruding height of a marking portion protruding from a profile line of the sidewall.

5. 5. The pneumatic tire according to claim 4, wherein a recess depth (B) of the recess is 50% or more of a protruding height of a marking portion protruding from a profile line of the sidewall.

6. 2. The pneumatic tire according to claim 1, wherein a protruding height of the marking portion protruding from a profile line of the sidewall is equal to or greater than 1.0 mm and equal to or less than 3.0 mm.

7. The pneumatic tire according to claim 1 , wherein the length of the marking portion in the tire radial direction is equal to or greater than 15 mm and equal to or less than 25 mm.

8. 2. The pneumatic tire of claim 1, wherein the tire section height is 155 mm or less.

9. 2. The pneumatic tire of claim 1, wherein the tire section height is 130 mm or less.

10. The pneumatic tire according to any one of claims 1 to 8, wherein the recess is a groove.

11. The pneumatic tire according to any one of claims 1 to 8, wherein the recess is a depression.

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