Pneumatic tire

Abstract

The present invention provides a pneumatic tire which suppresses unintended exposure of color rubber forming a side surface of a protruding part of a mark display part. A pneumatic tire is provided with a bead (10), a sidewall (20), and a tread (30), the sidewall (20) being provided with a mark display section (22A) including a protruding section protruding outward in the axial direction of the tire from a contour line (24) of the sidewall (20) in a radial surface (G) of the tire, the mark display section (22A) being provided with a cover rubber (22b) and a color rubber (22a), and the color rubber (22a) being provided between the cover rubber (22b) and the color rubber (22a). The color rubber (22a) is covered by the cover rubber (22b), at least a part of the color rubber (22a) corresponds to the mark display part (22A) and is exposed on the surface, the mark display part (22A) is further provided with a depression in the cross section view of the tire meridian plane (G), and the depression bottom of the depression is arranged at the position closer to the outer side of the tire axial direction than the contour line (24) of the tire side wall (20).

Description

Technical Field

[0001] The present invention relates to pneumatic tires. Background Art

[0002] In the past, in order to improve the aesthetics of pneumatic tires, it is known to display a logo display portion on the sidewall portion using colored rubber. Regarding the colored rubber, the sidewall portion is vulcanized and formed in a state where the surface is covered with a thin-walled cover rubber, and then the cover rubber corresponding to the logo display portion is removed by grinding, thereby exposing the colored rubber on the surface of the sidewall portion. (Patent Document 1)

[0003] [Prior technical literature]

[0004] [Patent Literature]

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-103849 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In recent years, there has been an increasing demand for a logo display portion to be displayed on a pneumatic tire having a small tire cross-sectional height. For a pneumatic tire having a small tire cross-sectional height, the length of the logo display portion in the tire radial direction is shortened, and the size of the logo display portion is reduced.

[0008] If the size of the emblem display portion of the pneumatic tire is reduced, the following situation may occur: the cover rubber covering the colored rubber is torn at the side of the protrusion forming the emblem display portion after the tire is vulcanized and molded, and the colored rubber is exposed in an unintended place, thereby deteriorating the appearance of the emblem display portion.

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pneumatic tire that suppresses unintentional exposure of colored rubber on the side surface of a protrusion forming a mark display portion.

[0010] Solutions to Solve Problems

[0011] The pneumatic tire of the present invention comprises: a pair of beads having a bead core; a pair of sidewalls extending radially outward from the pair of beads, respectively; and a tread arranged between the pair of sidewalls, wherein the sidewalls comprise a badge display portion, the badge display portion comprising a plurality of protrusions protruding axially outward from the contour line of the sidewalls in a cross-sectional view of the tire meridian plane, the badge display portion comprising: a cover rubber; and a colored rubber covered by the cover rubber and at least a portion of which is exposed on the surface corresponding to the badge display portion, the badge display portion further comprising a depression in a cross-sectional view of the tire meridian plane, the bottom of the depression being arranged at a position axially outward of the tire than the contour line of the sidewalls.

[0012] Effects of the Invention

[0013] According to the present invention, it is possible to provide a pneumatic tire in which unintentional exposure of colored rubber on the side surface of the protrusion forming the emblem display portion is suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 1 is a diagram showing a half cross section in the tire axial direction (tire meridian plane) of the tire according to the first embodiment of the present invention.

[0015] Figure 2 It is an enlarged cross-sectional view of a sidewall of the tire according to the first embodiment.

[0016] Figure 3A is from Figure 1 The view viewed from the E direction is a diagram showing the periphery of the mark display portion.

[0017] Figure 3B is from Figure 1 The arrow view viewed in the E direction is a diagram showing the smallest quadrilateral circumscribing the outline of the mark display portion.

[0018] Figure 4A is from Figure 1 The view viewed from the E direction is a diagram showing the periphery of another example of the mark display portion.

[0019] Figure 4B is from Figure 1 The E-direction view is the same as Figure 4A The label shows the figure of the smallest quadrilateral circumscribing the outline of the part.

[0020] Figure 5 It is an enlarged cross-sectional view of a sidewall of a tire according to the second embodiment.

[0021] Fig. 6A is from Figure 5 The view viewed from the E direction is a diagram showing the periphery of the mark display portion.

[0022] Figure 6B is from Figure 5 The arrow view viewed in the E direction is a diagram showing the smallest quadrilateral circumscribing the outer edge of the mark display portion.

[0023] Fig. 7A is from Figure 5 The view viewed from the E direction is a diagram showing the periphery of another example of the mark display portion.

[0024] Figure 7B is from Figure 5 The E-direction view is the same as Fig. 7AThe label shows the smallest quadrilateral circumscribing the outer edge of the part.

[0025] Description of reference numerals:

[0026] 1 Pneumatic tire

[0027] 10 Bead

[0028] 20 Sidewall

[0029] 22 Logo display unit

[0030] 22a Colored Rubber

[0031] 22b Cover rubber

[0032] 23 slots (recessed)

[0033] 24 Contour lines

[0034] 25 Depression

[0035] 30 Tread

[0036] A Depression width, groove width, pit width

[0037] B Depth of depression, groove, or pit

[0038] C Protrusion height

[0039] D Mark display area

[0040] E Minimum quadrilateral area. DETAILED DESCRIPTION

[0041] (First Embodiment)

[0042] Hereinafter, embodiments will be described with reference to the drawings.

[0043] Figure 1 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 the first embodiment of the present invention. Figure 2 It is a diagram showing an enlarged cross-sectional view of a sidewall of the tire 1 according to the embodiment. Figure 3A is from Figure 1 The view viewed from the E direction is a diagram showing the periphery of the mark display portion. Figure 3B is from Figure 1 The view viewed in the E direction shows the smallest quadrilateral circumscribing the outline of the logo display portion. Figure 4A is from Figure 1 The view viewed from the E direction is a diagram showing the periphery of another example of the mark display portion. Figure 4B is from Figure 1 The E-direction view is the same as Figure 4A The label shows the figure of the smallest quadrilateral circumscribing the outline of the part.

[0044] Figure 1 The cross-sectional view is an axial cross-sectional view (a tire meridian cross-sectional view) of the tire in an unloaded state obtained by mounting the tire 1 on a regular rim (not shown) and filling it with a regular internal pressure. A regular rim refers to a rim whose specifications are determined for each tire in a specification system including the specifications to which the tire is based. For example, in the case of JATMA, it is a standard rim, and in the case of TRA and ETRTO, it is a "measuring rim". The regular internal pressure refers to the air pressure determined for each tire in each specification in a specification system including the specifications to which the tire is based. In the case of truck and bus tires and light truck tires, in the case of JATMA, it is the maximum air pressure, in the case of TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and in the case of ETRTO, it is "INFLATION PRESSURE". In the case of a tire for a passenger car, the pressure is generally set to 180 kPa, but in the case of a tire having Extra Load or Reinforced indicated on the tire, the pressure is set to 220 kPa.

[0045] The basic structure of the tire 1 is bilaterally symmetrical in a cross section along the tire axial direction (tire meridian plane). Figure 1 The half cross section of the right half of the tire 1 is shown, and the left half (not shown) has the same structure. Figure 1 In the figure, reference numeral S1 is the tire equatorial plane. The tire equatorial plane S1 is a plane that is orthogonal to the tire rotation axis (tire meridian) and is located at the tire axial center.

[0046] Here, the tire axial direction is the direction parallel to the tire rotation axis. Figure 1 The left-right direction of the paper. Figure 1 In the figure, the tire axial direction X is shown. The inner side of the tire axial direction is the direction close to the tire equatorial plane S1. Figure 1 The tire axially outward is the direction away from the tire equatorial plane S1. Figure 1 The middle is the right side of the paper.

[0047] In addition, the tire radial direction is the direction perpendicular to the tire rotation axis. Figure 1 The up and down direction of the paper. Figure 1 In the figure, the tire radial direction Y is shown. The radial outer side of the tire is the direction away from the tire rotation axis. Figure 1 The tire radial inner side is the direction close to the tire rotation axis. Figure 1The middle is the lower side of the paper.

[0048] In addition, the tire circumference Figure 3A The center is the arc Z direction, and the arc Z is an arc with the tire rotation axis as the center.

[0049] like Figure 1 As shown, the tire 1 includes a pair of tire beads 10, a pair of sidewalls 20 extending radially outward from the pair of tire beads 10, a tread 30 arranged between the pair of sidewalls 20, a carcass ply 60 arranged to be spanned between the pair of tire beads 10, and an airtight layer 70 arranged on the tire inner cavity side of the carcass ply 60.

[0050] A pair of beads 10 are arranged at both ends of the tire axial direction and the inner side of 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 of the tire radial direction, a chafer 13 and a rim strip rubber 14.

[0051] The bead core 11 is a toroidal member in which a rubber-covered metal bead wire is wound multiple times in the tire circumferential direction. The bead core 11 is a member that plays a role in fixing the tire 1 filled with air to the rim.

[0052] The bead filler 12 has a tapered shape with a thickness decreasing as it extends from the inner side of the tire radial direction to the outer side of 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, a rubber having a higher hardness than the surrounding rubber members. The radially inner surface of the bead filler 12 is joined to the radially outer surface of the bead core 11.

[0053] The chafer 13 also surrounds the outer side of the carcass ply 60 , and the carcass ply 60 surrounds the bead core 11 and the bead filler 12 .

[0054] The rim strip rubber 14 is arranged on the tire axially outer side of the chafer 13 and the carcass ply 60. The rim strip rubber 14 is a member that comes into contact with a rim to which the tire 1 is mounted.

[0055] The sidewall 20 includes a sidewall rubber 21 disposed on the outer side of the tire axial direction of the carcass ply 60, and a logo display portion 22A. The sidewall rubber 21 and the logo display portion 22A constitute the outer wall surface of the tire 1. The sidewall 20 is the most curved portion when the tire 1 plays a cushioning role. Therefore, in general, the sidewall rubber 21 of the sidewall 20 is made of a soft rubber with fatigue resistance.

[0056] The details of the mark display portion 22A will be described later.

[0057] The tread 30 includes an annular belt layer 31 and a cap layer 32 , and a tread rubber 33 .

[0058] The belt layer 31 is arranged outside the carcass ply 60 in the tire radial direction. The band layer 32 is arranged outside the belt layer 31 in the tire radial direction.

[0059] The belt layer 31 is a member for reinforcing the tread 30. The belt layer 31 of the present embodiment is a two-layer structure having an outer belt layer 311 and an inner belt layer 312. The outer belt layer 311 and the inner belt layer 312 both have a structure in which a plurality of steel cords or the like are covered with rubber. It should be noted that the belt layer 31 is not limited to a two-layer structure, and may also have a structure of one layer or more than three layers.

[0060] The cap layer 32 is a member that reinforces the tread 30 together with the belt layer 31. The cap layer 32 has a structure in which a plurality of organic fiber cords having insulating properties such as polyamide fiber are covered with rubber. By providing the cap layer 32, it is possible to improve durability and reduce road noise during running.

[0061] The tread rubber 33 is disposed on the outer side in the tire radial direction of the cap layer 32. The tread rubber 33 is a member constituting a tread 34 which is the outer surface of the tread 30.

[0062] The carcass ply 60 constitutes a ply layer that becomes the skeleton of the tire 1. The carcass ply 60 is embedded in the tire 1 in the form of a pair of sidewalls 20 and a tread 30 between a pair of beads 10. The carcass ply 60 includes a plurality of carcass cords (not shown) that become the skeleton of the tire 1. For example, the plurality of carcass cords extend along the tire axial direction and are arranged in the tire circumferential direction. The carcass cords are composed of insulating organic fiber cords such as polyester and polyamide. The plurality of carcass cords are covered with rubber to constitute the carcass ply 60.

[0063] The carcass ply 60 includes a ply main body 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 bent portions 602 folded back at the bead core 11 from the ply main body 601, and a pair of folded back portions 603 extending radially outward from the folded portions 602. The ply main body 601, the bent portions 602, and the folded back portions 603 surround the bead filler 12 and the bead core 11. The folded back portions 603 at the outer side of the bead filler 12 in the tire radial direction overlap with the ply main body 601.

[0064] The carcass ply 60 of the embodiment has a two-layer structure, but the carcass ply 60 is not limited to the two-layer structure, and may have a one-layer structure or a three-layer or more structure.

[0065] The chafer 13 of the tire bead 10 is provided so as to surround the end portion of the carcass ply 60 including the bent portion 602 on the inner side of the tire radial direction. In addition, the rim strip rubber 14 is arranged on the outer side of the chafer 13 and the folded portion 603 of the carcass ply 60 in the tire axial direction. The end portion of the rim strip rubber 14 on the outer side of the tire radial direction is covered by the sidewall rubber 21.

[0066] The airtight layer 70 covers the inner surface of the carcass ply main body 601 of the carcass ply 60 and the inner surface of the chafer 13 of the pair of tire beads 10. The airtight layer 70 is made of air-permeable rubber to prevent the air in the tire cavity from leaking to the outside. The inner surface of the airtight layer 70 constitutes the tire inner surface 701 between the pair of tire beads 10. The airtight layer 70 of the tire 1 of this embodiment is composed of two layers: an inner airtight layer 702 and an outer airtight layer 703.

[0067] Figure 1 A cross section in the tire axial direction (tire meridian plane) of a tire 1 which is a pneumatic tire according to the embodiment is shown.

[0068] like Figure 1 As shown, the sidewall 20 includes a sidewall rubber 21 and a logo display portion 22A.

[0069] The emblem display portion 22A includes a colored rubber 22a and a cover rubber 22b. The colored rubber 22a is disposed on the outer side in the tire axial direction of the carcass ply 60. The colored rubber 22a is provided on the sidewall 20 in an annular shape.

[0070] Figure 2 It is an enlarged cross-sectional view of the sidewall of the tire 1 .

[0071] like Figure 2 As shown, the cover rubber 22b is arranged on the tire outer surface side of the color rubber 22a. In addition, the cover rubber 22b is arranged so as to cover the color rubber 22a.

[0072] The logo display portion 22A is formed so that a portion of the sidewall 20 of the tire 1 in the tire circumferential direction protrudes outward in the tire axial direction from the contour line 24 of the sidewall 20 when the tire 1 is vulcanized. After the tire 1 is vulcanized, the cover rubber 22b corresponding to the portion F visually recognized as the logo is removed by grinding, thereby exposing the colored rubber 22a. As a result, the portion F of the logo display portion 22A visually recognized as the logo is exposed on the surface of the sidewall 20.

[0073] like Figure 2As shown in FIG. 1 , the indicia display portion 22A has a groove 23 that is a depression in the cross-sectional view of the tire meridian plane. The mold for vulcanization molding the tire 1 has a depression for forming the indicia display portion 22A. The groove 23 in the cross-sectional view of the tire meridian plane of the indicia display portion 22A is formed by a raised portion of the mold disposed at a part of the depression during vulcanization molding of the tire 1. It should be noted that the tire meridian plane is selected so that the groove width (A) mm of the groove 23 described later in the tire circumferential direction of the indicia display portion 22A becomes the maximum groove width.

[0074] It should be noted that the groove 23 has a concave shape in a cross-sectional view taken along the tire meridian plane, and extends and opens in one direction in a front view of the mark display portion 22A.

[0075] like Figure 2 As shown in the figure, the groove width (A) mm of the groove 23, which is the groove width (A) mm, is defined by the distance between the surfaces of the cover rubber 22b facing each other at the groove upper end of the groove 23 after the colored rubber 22a corresponding to the logo display portion 22A is exposed. The groove depth (B) mm of the groove 23, which is the groove depth (B) mm, is defined by the distance from the groove upper end of the groove 23 to the groove bottom, which is the groove bottom, which is the groove depth (B) mm.

[0076] The cover rubber 22b is arranged on the surface of the groove 23. That is, the cover rubber 22b is pressed by the raised portion arranged in the mold during the vulcanization molding of the tire 1. At this time, the groove 23 is formed along the shape of the raised portion arranged in the mold. The cover rubber 22b pressed by the thin raised portion arranged in the mold is assumed to be subjected to a strong tensile force during the vulcanization molding of the tire 1, and therefore it is considered that the cover rubber 22b is damaged near the mark display portion 22A.

[0077] In recent years, the number of cases where the emblem display portion 22A is displayed on a pneumatic tire having a small tire cross-sectional height has increased. The length of the emblem display portion 22A in the tire radial direction of a pneumatic tire having a small tire cross-sectional height has become shorter. The emblem display portion 22A having a short length in the tire radial direction is molded by a mold having a thin ridge portion, and therefore it is required to suppress the damage of the cover rubber 22b near the emblem display portion 22A.

[0078] Figure 3A This is a view viewed from the E direction of the tire 1 according to the embodiment, and is a view showing an example of the mark display portion 22A. Figure 3A In FIG. 1 , as an example of a portion F in the mark display portion 22A that is visually recognized as a mark, the Latin letter "E" is shown. Figure 1In the arrow view observed in the E direction, the portion F of the logo display portion 22A that is visually identified as a logo is formed by a colored rubber 22a corresponding to the logo display including text, graphics, and symbols protruding from the surface of the sidewall 20, and an outer frame 26 obtained based on a cover rubber 22b configured in a manner to surround the outer periphery of the colored rubber 22a. The outline of the portion F of the logo display portion 22A that is visually identified as a logo is formed by the exposed surface of the colored rubber 22a at a position of a protrusion height (C) described later in the axial direction of the tire, and the outer periphery of the outer frame 26 obtained based on the cover rubber 22b configured in a manner to surround the outer periphery of the colored rubber 22a. It should be noted that, from Figure 1 The arrow view viewed from the E direction is a side view of the tire 1, that is, a front view of the mark display portion 22A.

[0079] For example, Figure 3A As shown in FIG. 1 , when the Latin letter "E" is arranged as the marking display portion 22A in such a manner that the lower side of the letter faces the tire rotation axis and the upper side of the letter faces the tire radially outer side, the three transverse lines constituting the letter "E" protrude as three protrusions to the tire axially outer side from the contour line 24 of the sidewall 20 in the cross-sectional view of the tire meridian plane G. In addition, two grooves 23 are provided between each of the three protrusions protruding to the tire axially outer side in the cross-sectional view of the tire meridian plane G. That is, the marking display portion 22A has the grooves 23 as recesses between the plurality of protrusions in the cross-sectional view of the tire meridian plane G.

[0080] Figure 4A 2 is a view viewed from the E direction of the tire 1 according to the embodiment, and is a view showing another example of the mark display portion 22A. Figure 4A In FIG. 1 , as an example of a portion F in the mark display portion 22A that is visually recognized as a mark, the Latin letter “O” is illustrated. Figure 4A As shown in FIG. 1 , when the Latin letter "O" is arranged as the mark display portion 22A in such a manner that the lower side of the letter faces the tire rotation axis and the upper side of the letter faces the tire radially outward, in the cross-sectional view of the tire meridian plane G, the two transverse lines constituting the letter "O" protrude as two protrusions to the tire axially outward from the contour line 24 of the sidewall 20. In addition, in the cross-sectional view of the tire meridian plane G, there is a dimple 25 as a depression arranged in such a manner that it is surrounded by a plurality of protrusions protruding to the tire axially outward. It should be noted that, in this case, the dimple width (A) as the dimple width (A) of the dimple is equivalent to the groove width (A), the dimple depth (B) as the dimple depth (B) of the dimple is equivalent to the groove depth (B), and the dimple bottom as the dimple bottom is equivalent to the groove bottom.

[0081] Here, the mark display area (D) is formed by the outline of the portion F of the mark display portion 22A that is visually recognized as a mark. It should be noted that, in the case where a part of the mark such as the Latin letter "O" has a dimple 25 arranged so as to be surrounded by a plurality of protrusions, the mark display area (D) is an area obtained by removing the area of ​​the dimple 25 on the exposed surface of the colored rubber 22a in the front view of the mark display portion 22A.

[0082] like Figure 3B As shown, the logo display portion 22A has a minimum quadrilateral area (E) which is a quadrilateral circumscribing the outline of a portion F of the logo display portion 22A that is visually recognized as a logo and is formed so that its area becomes minimum. Figure 3B This is an example of the mark display portion 22A of the Latin letter "E".

[0083] like Figure 4B As shown, the logo display portion 22A has a minimum quadrilateral area (E) which is a quadrilateral circumscribing the outline of a portion F of the logo display portion 22A that is visually recognized as a logo and is formed so that its area becomes minimum. Figure 4B This is an example of the mark display portion 22A of the Latin letter "O".

[0084] In this embodiment, in order to avoid applying a strong tensile force to the cover rubber 22b on the surface of the groove 23, the groove bottom of the groove 23, which is a concave bottom, is arranged at a position closer to the tire axial outside than the contour line 24 of the sidewall 20. Thus, the groove 23 is formed by a mold having a gently shaped bulge. Therefore, it is possible to appropriately suppress the tearing of the cover rubber 22b covering the colored rubber 22a at the groove 23 on the side of the protrusion forming the logo display part 22A after the tire 1 is vulcanized and molded. Therefore, it is possible to suppress the unintentional exposure of the colored rubber 22a at the logo display part 22A.

[0085] In addition, in the present embodiment, in the tire side view, i.e., in the front view of the logo display portion 22A, the relationship between the logo display portion area (D) formed by the outline of the logo display portion 22A and the minimum quadrilateral area (E) is preferably such that the logo display portion area (D) ÷ the minimum quadrilateral area (E) ≥ 70%, and the minimum quadrilateral is a quadrilateral circumscribed with the outline of the logo display portion 22A and formed in such a way that its area is minimized. Thus, the tire 1 can further effectively suppress the unintended exposure of the colored rubber 22a at the groove 23 on the side of the protruding portion of the logo display portion 22A.

[0086] In addition, in the present embodiment, from the point that unintentional exposure of the colored rubber 22a can be more appropriately suppressed, the length of the depression depth (B) of the depression in the mark display portion 22A is preferably 80% or less of the protrusion height (C), and more preferably 50% or more and 80% or less.

[0087] [Example]

[0088] The following describes the examples. Examples 1 to 8 were produced as shown in Table 1. The tires of Examples 1 to 8 had the same structure as the tire 1 of the above-mentioned embodiment having the indicia display portion 22A, and the groove bottom of the groove 23 as the concave bottom was arranged at a position axially outward of the tire relative to the contour line 24 of the sidewall 20. In addition, Comparative Examples 1 to 4 were produced in which the groove bottom of the groove 23 as the concave bottom was arranged on the contour line 24 of the sidewall 20.

[0089] With respect to each embodiment and each comparative example, the protruding height (C) of the label display portion 22A is set to 1.5 mm. With respect to embodiments 1 to 4, the heightening amount of the label display portion 22A is set to 0.3 mm. With respect to embodiments 5 to 8, the heightening amount of the label display portion 22A is set to 0.7 mm. The so-called heightening amount is defined by the distance from the contour line 24 of the sidewall 20 to the bottom of the groove 23 of the label display portion 22A. That is, the recessed depth (B) mm of the label display portion 22A of embodiments 1 to 4 is 1.2 mm, and the recessed depth (B) mm of the label display portion 22A of embodiments 5 to 8 is 0.8 mm. With respect to embodiments 1 to 4, the heightening amount ratio of the label display portion 22A is set to 20%. With respect to embodiments 5 to 8, the heightening amount ratio of the label display portion 22A is set to 47%. The heightening amount ratio is the ratio of the heightening amount to the protruding height (C) of the label display portion 22A. That is, the recessed depth (B) of the mark display portion 22A in Examples 1 to 4 is 80% of the protruding height (C). In addition, the recessed depth (B) of the mark display portion 22A in Examples 5 to 8 is 53% of the protruding height (C).

[0090] In addition, in the following (Formula 1) which represents the relationship between the area of ​​the emblem display portion (D) formed by the outline of the emblem display portion 22A and the area of ​​the minimum quadrilateral (E), a Latin alphabetic character is used whose Y value is in the range of 75.9% to 83.4%, and the minimum quadrilateral is a quadrilateral circumscribed with the outline of the emblem display portion 22A and formed in a manner in which its area is minimized. For each tire produced, it is evaluated whether the cover rubber 22b is damaged. It should be noted that, in the case where the cover rubber 22b is almost not damaged and the unintentional exposure of the color rubber 22a cannot be confirmed, the evaluation result is set to "○", and in the case where damage occurs but the exposure of the color rubber 22a from the damaged portion is not conspicuous, the evaluation result is set to "Δ", and in the case where damage occurs and the exposure of the color rubber 22a is conspicuous, the evaluation result is set to "×". More specifically, when the ratio of the exposed length to the protruding height (C) is less than 10%, the evaluation result is set to "○", when the ratio of the exposed length to the protruding height (C) is 10% to 30%, the evaluation result is set to "Δ", and when the ratio of the exposed length to the protruding height (C) exceeds 30%, the evaluation result is set to "○". The exposed length is the length of the color rubber 22a exposed from the damaged portion of the cover rubber 22b.

[0091] The area of ​​the logo display (D) ÷ the area of ​​the smallest quadrilateral (E) = Y% (Formula 1)

[0092]

Table 1

[0093]

[0094] As shown in Table 1, in Comparative Examples 1 to 4 where the groove bottom of the groove 23 as the concave bottom is arranged on the contour line 24 of the sidewall 20, the cover rubber 22b is damaged and the exposure of the color rubber 22a is conspicuous. On the other hand, in Examples 1 to 4 where the height ratio is 20%, damage occurs, but the exposure of the color rubber 22a is not conspicuous. In Examples 5 to 8 where the height ratio is 47%, the cover rubber 22b is almost not damaged and unintentional exposure of the color rubber 22a is not confirmed.

[0095] From the results of Table 1, it can be confirmed that by arranging the groove bottom of the groove 23 as the bottom of the depression at a position closer to the tire axial outer side than the contour line 24 of the sidewall 20, the cover rubber 22b covering the color rubber 22a at the logo display part 22A after the tire 1 is vulcanized and molded can be appropriately suppressed. Therefore, the unintentional exposure of the color rubber 22a at the logo display part 22A can be suppressed. From the results of Examples 5 to 8, it can be confirmed that when the depression depth (B) of the depression in the logo display part 22A is 53% of the protrusion height (C), the exposure length can be suppressed to less than 0.1 mm.

[0096] In addition, the value of Y in (Formula 1) is preferably 70% or more. Thus, the cover rubber 22b covering the color rubber 22a at the label display portion 22A after the tire 1 is vulcanized and molded can be more appropriately suppressed. In addition, the value of Y in (Formula 1) can also be 75% or more and 85% or less. Even in such a tire 1, the cover rubber 22b covering the color rubber 22a at the label display portion 22A after the tire 1 is vulcanized and molded can be appropriately suppressed.

[0097] The thickness of the cover rubber 22b is preferably 0.08 mm to 0.20 mm. For example, if the cover rubber 22b is 0.08 mm to 0.20 mm, even if it is pressed by the raised portion of the mold, damage caused by the tensile force can be appropriately suppressed.

[0098] In order to suppress the damage caused by the tensile force in the cover rubber 22b, it is also considered to make the groove bottom of the groove 23 shallower. However, when the distance between the groove bottom of the groove 23 and the exposed surface of the color rubber 22a corresponding to the logo display part 22A is close, the visual recognition of the outline of the logo display part 22A is poor, and the appearance is poor. Therefore, when considering the relationship between suppressing the damage caused by the tensile force and the appearance, the groove depth (B) is preferably the distance between the outline line 24 of the sidewall 20 and the exposed surface of the color rubber 22a, that is, the protruding height (C) of the logo display part 22A ( Figure 2 ) is more than 50% of the length.

[0099] This makes it possible to clearly see the outline of the mark display portion 22A and improve the appearance, while suppressing unintentional exposure of the colored rubber 22 a due to damage of the cover rubber 22 b.

[0100] Even if the protruding height (C) of the label display portion 22A protrudes significantly from the contour line 24 of the sidewall 20, the aesthetics deteriorates and the distance between the mold pit and the ridge increases, so the tensile force generated in the cover rubber 22b also increases, and the possibility of damage also increases. In addition, when the protruding amount is extremely small, the contour of the label display portion 22A is not easy to be seen thoroughly, so the protruding height (C) of the label display portion 22A is preferably greater than 1 mm and less than 3 mm.

[0101] The number of cases where the emblem display portion 22A is displayed on a pneumatic tire with a small tire cross-sectional height is increasing. For a pneumatic tire with a small tire cross-sectional height, the length of the emblem display portion 22A in the tire radial direction becomes shorter, and the size of the emblem display portion 22A also becomes smaller. In this case, when the length of the emblem display portion 22A in the tire radial direction is too small, the appearance becomes poor. Therefore, the length of the emblem display portion 22A in the tire radial direction is preferably 15 mm or more and 25 mm or less when the emblem display portion 22A is viewed from the front.

[0102] When the length of the indicia display portion 22A in the tire radial direction in the front view of the indicia display portion 22A is 15 mm to 25 mm, the tire cross-sectional height is preferably 155 mm or less. More preferably, the tire cross-sectional height is 130 mm or less.

[0103] According to the tire 1 according to the above-described first embodiment, the following effects are achieved.

[0104] (1) The tire 1 involved in the first embodiment is a pneumatic tire, which includes: a pair of beads 10, which have a bead core 11; a pair of sidewalls 20, which extend radially outward from the pair of beads 10; and a tread 30, which is arranged between the pair of sidewalls 20, wherein the sidewalls 20 include a logo display portion 22A, which includes a protrusion that protrudes axially outward from the contour line 24 of the sidewalls 20 in a cross-sectional view of the tire meridian plane G, and the logo display portion 22A includes: a cover rubber 22b; and a colored rubber 22a, which is covered by the cover rubber 22b and at least a portion is exposed on the surface, and the logo display portion 22A has a depression in a cross-sectional view of the tire meridian plane G, and the bottom of the depression is arranged at a position closer to the outside of the tire axial direction than the contour line 24 of the sidewalls 20.

[0105] This can suppress unintended exposure of the colored rubber 22 a in the mark display portion 22A.

[0106] (2) Based on the tire 1 described in (1), when viewed from the side of the tire, i.e., when viewing the logo display portion 22A from the front, the relationship between the logo display portion area (D) formed by the outline of the logo display portion 22A and the minimum quadrilateral area (E) is: logo display portion area (D) ÷ minimum quadrilateral area (E) ≥ 70%, wherein the minimum quadrilateral is a quadrilateral circumscribed with the outline of the logo display portion 22A and is formed in such a way that its area is minimized.

[0107] Thus, the tire 1 can further effectively suppress unintended exposure of the colored rubber 22 a in the mark display portion 22A.

[0108] (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.

[0109] Thus, the tire 1 can further effectively suppress the unintended exposure of the colored rubber 22a at the mark display portion 22A. In addition, at the mark display portion 22A, the exposed portion of the colored rubber 22a can be visually recognized sufficiently wider than the thickness of the cover rubber 22b, thereby improving the appearance of the mark display portion 22A.

[0110] (4) In the tire 1 described in (1) to (3), the length of the recessed depth (B) is a length that is not more than 80% of the protruding height of the indicia display portion protruding from the contour line 24 of the sidewall 20 .

[0111] Thus, the tire 1 can further effectively suppress unintended exposure of the colored rubber 22 a in the mark display portion 22A.

[0112] (5) In the tire 1 described in (4), the depth (B) of the depression is equal to or greater than 50% of the protruding height (C) of the mark display portion 22A protruding from the contour line 24 of the sidewall 20 .

[0113] Thus, the outline of the logo display portion 22A can be clearly seen to ensure the appearance, while preventing the unintentional exposure of the colored rubber 22a due to damage of the cover rubber 22b. In addition, in the logo display portion 22A, the exposed portion of the colored rubber 22a can be visually recognized sufficiently wide compared to the thickness of the cover rubber 22b, thereby improving the appearance of the logo display portion 22A.

[0114] (6) In the tire 1 described in (1) to (5), a protruding height (C) of the mark display portion 22A protruding from the outline 24 of the sidewall 20 is 1.0 mm or more and 3.0 mm or less.

[0115] This reduces the tensile force generated in the cover rubber 22b of the tire 1, and reduces the possibility of damage. In addition, the light and dark of the surface of the colored rubber 22a of the mark display portion 22A and the outline 24 become clear, and the appearance is improved.

[0116] (7) In the tire 1 described in (1) to (6), the length of the mark display portion 22A in the tire radial direction is 15 mm or more and 25 mm or less.

[0117] In such a tire 1 as well, unintentional exposure of the colored rubber 22 a can be suppressed while ensuring the external appearance.

[0118] (8) In the tire 1 described in (1) to (7), the tire cross-sectional height is 155 mm or less.

[0119] In such a tire 1 as well, unintentional exposure of the colored rubber 22 a can be suppressed while ensuring the external appearance.

[0120] (9) In the tire 1 described in (1) to (8), the tire cross-sectional height is 130 mm or less.

[0121] In such a tire 1 as well, unintentional exposure of the colored rubber 22 a can be suppressed while ensuring the external appearance.

[0122] (10) In the tire 1 described in (1) to (9), the depression is a groove 23 .

[0123] In such a tire 1, the effects (1) to (9) are also achieved.

[0124] (11) In the tire 1 described in any of (1) to (9), the depressions are dimples 25 .

[0125] In such a tire 1, the effects (1) to (9) are also achieved.

[0126] (Second Embodiment)

[0127] Next, refer to Figures 5 to 7B The second embodiment of the present invention will be described. In the second embodiment, the shape of the label display unit 22B involved in the present invention is different from the label display unit 22A of the first embodiment, and the other structures are the same or similar. Therefore, in the following description, the same reference numerals are marked on the same components as the first embodiment, and the description thereof is omitted or simplified, and the description is mainly about the differences.

[0128] Figure 5 It is an enlarged cross-sectional view of a sidewall of a tire according to the second embodiment. Fig. 6A is from Figure 5 The view viewed from the E direction is a diagram showing the periphery of the mark display portion. Figure 6B is from Figure 5 The arrow view viewed in the E direction is a diagram showing the smallest quadrilateral circumscribing the outer edge of the mark display portion. Fig. 7A is from Figure 5 The view viewed from the E direction is a diagram showing the periphery of another example of the mark display portion. Figure 7B is from Figure 5 The E-direction view is the same as Fig. 7A The label shows the smallest quadrilateral circumscribing the outer edge of the part.

[0129] like Figure 5 As shown, the mark display portion 22B has grooves 23 serving as depressions of different sizes in a cross-sectional view taken along the tire meridian plane.

[0130] exist Fig. 6A In FIG. 1 , as an example of a portion F in the mark display portion 22B that is visually recognized as a mark, the Latin letter "E" is shown. Figure 5 In the arrow view viewed from the E direction, the portion F of the mark display portion 22B that is visually recognized as a mark is formed by the colored rubber 22a corresponding to the mark display including characters, graphics, and symbols protruding from the surface of the sidewall 20, and the outer frame 26 and the inner frame 27 obtained by the cover rubber 22b arranged so as to surround the colored rubber 22a. The outer periphery of the portion F of the mark display portion 22B that is visually recognized as a mark forms the outer edge H of the portion F.

[0131] For example, Fig. 6A As shown, when the Latin letter "E" is arranged as the marking display portion 22B in a manner such that the lower side of the letter is toward the tire rotation axis and the upper side of the letter is toward the radially outer side of the tire, in a cross-sectional view of the tire meridian plane G, the three transverse lines constituting the letter "E" protrude axially outward of the tire more than the contour line 24 of the sidewall 20 as six protrusions corresponding to the three transverse lines.

[0132] In addition, five grooves 23 are provided between each of the six protrusions protruding outward in the tire axial direction in a cross-sectional view along the tire meridian plane G. That is, the indicia display portion 22B has grooves 23 as recesses between the plurality of protrusions in a cross-sectional view along the tire meridian plane G.

[0133] Here, in the front view of the logo display portion 22B, the first groove 23, the third groove 23, and the fifth groove 23 from the top of the five grooves 23 are formed by the opposing surfaces of the cover rubber 22b of the inner frame 27. In other words, in the front view of the logo display portion 22B, the first groove 23, the third groove 23, and the fifth groove 23 from the top of the five grooves 23 are present on the inner side of the outer edge H of the portion F of the logo display portion 22B that is visually recognized as the logo.

[0134] In addition, in the front view of the logo display portion 22B, the second groove 23 and the fourth groove 23 from the top of the five grooves 23 are formed by the outer edge H of the portion F in the logo display portion 22B that is visually recognized as the logo. In other words, in the front view of the logo display portion 22B, the second groove 23 and the fourth groove 23 from the top of the five grooves 23 are present outside the outer edge H of the portion F in the logo display portion 22B that is visually recognized as the logo.

[0135] Here, the mark display portion area (D) is formed by the inner side of the outer edge H of the portion F of the mark display portion 22B that is visually recognized as a mark.

[0136] like Figure 6BAs shown, the logo display portion 22B has a minimum quadrilateral area (E) which is a quadrilateral circumscribing the outer edge H of a portion F of the logo display portion 22B that is visually recognized as a logo and is formed so that its area becomes minimum. Figure 6B This is an example of the mark display portion 22B of the Latin letter "E".

[0137] The groove bottom of the groove 23 as a concave bottom existing outside the outer edge H of the portion F of the mark display portion 22B visually recognized as the mark is preferably arranged axially outward from the contour line 24 of the sidewall 20 .

[0138] This can suppress unintended exposure of the colored rubber 22a in the mark display portion 22B. In addition, the outer edge H of the mark display portion 22B can be clearly seen.

[0139] In addition, preferably, when viewed from the side of the tire, that is, when viewing the logo display portion 22B from the front, the relationship between the logo display portion area (D) formed by the inner side of the outer edge H of the logo display portion 22B and the minimum quadrilateral area (E) is: logo display portion area (D) ÷ minimum quadrilateral area (E) ≥ 70%, and the minimum quadrilateral is a quadrilateral circumscribed to the outer edge H of the logo display portion 22B and is formed in such a way that its area is minimized.

[0140] Thus, the tire 1 can further effectively suppress unintended exposure of the colored rubber 22 a in the groove 23 of the protruding portion of the mark display portion 22B.

[0141] More preferably, the groove 23 having a concave bottom inside the outer edge H of the portion F of the mark display portion 22B that is visually recognized as a mark has its groove bottom disposed axially outward from the contour line 24 of the sidewall 20 .

[0142] This can suppress unintended exposure of the colored rubber 22a in the mark display portion 22B. In addition, the inner periphery formed by the inner frame 27 of the mark display portion 22B can be clearly seen.

[0143] exist Fig. 7A In FIG. 1 , as an example of a portion F in the mark display portion 22B that is visually recognized as a mark, the Latin letter "O" is shown. Figure 5In the arrow view viewed from the E direction, the portion F of the mark display portion 22B that is visually recognized as a mark is formed by the colored rubber 22a corresponding to the mark display including characters, graphics, and symbols protruding from the surface of the sidewall 20, and the outer frame 26 and the inner frame 27 obtained by the cover rubber 22b arranged so as to surround the colored rubber 22a. The outer periphery of the portion F of the mark display portion 22B that is visually recognized as a mark forms the outer edge H of the portion F.

[0144] For example, Fig. 7A As shown, when the Latin letter "O" is arranged as the marking display portion 22B in a manner such that the lower side of the letter is toward the tire rotation axis and the upper side of the letter is toward the radially outer side of the tire, in a cross-sectional view of the tire meridian plane G, the two transverse lines constituting the letter "O" serve as four protrusions that protrude axially outward from the contour line 24 of the sidewall 20 of the tire.

[0145] In addition, in a cross-sectional view along the tire meridian plane G, one dimple 25 as a depression is provided so as to be surrounded by a plurality of protrusions protruding outward in the tire axial direction, and two grooves 23 as depressions are provided.

[0146] Here, in the front view of the logo display portion 22B, the two grooves 23 are formed by the opposing surfaces of the cover rubber 22b of the inner frame 27. In other words, in the front view of the logo display portion 22B, the two grooves 23 exist inside the outer edge H of the portion F of the logo display portion 22B that is visually recognized as a logo.

[0147] In addition, when the logo display portion 22B is viewed from the front, one dimple is formed by the outer edges H of the portion F of the logo display portion 22B that is visually recognized as the logo. In other words, when the logo display portion 22B is viewed from the front, one dimple exists outside the outer edges H of the portion F of the logo display portion 22B that is visually recognized as the logo.

[0148] Here, the mark display area (D) is formed by the inner side of the outer edge H of the portion F of the mark display portion 22B that is visually recognized as a mark. It should be noted that, in the case where a portion of a mark such as the Latin letter "O" has a dimple 25 arranged so as to be surrounded by a plurality of protrusions, the mark display area (D) is an area obtained by removing the area of ​​the dimple 25 on the exposed surface of the colored rubber 22a in the front view of the mark display portion 22B. That is, the mark display area (D) is formed by the inner side surrounded by the outer edge H of the portion F.

[0149] like Figure 7BAs shown, the logo display portion 22B has a minimum quadrilateral area (E) which is a quadrilateral circumscribing the outer edge H of a portion F of the logo display portion 22B that is visually recognized as a logo and is formed so that its area becomes minimum. Figure 7B This is an example of the mark display portion 22B of the Latin letter "O".

[0150] The dimples 25 that are recessed outside the outer edge H of the portion F that is visually recognized as a mark in the mark display portion 22B preferably have their bottoms disposed axially outward from the contour line 24 of the sidewall 20 .

[0151] This can suppress unintended exposure of the colored rubber 22a in the mark display portion 22B. In addition, the outer edge H of the mark display portion 22B can be clearly seen.

[0152] In addition, preferably, when viewed from the side of the tire, that is, when viewing the logo display portion 22B from the front, the relationship between the logo display portion area (D) formed by the inner side of the outer edge H of the logo display portion 22B and the minimum quadrilateral area (E) is: logo display portion area (D) ÷ minimum quadrilateral area (E) ≥ 70%, and the minimum quadrilateral is a quadrilateral circumscribed to the outer edge H of the logo display portion 22B and is formed in such a way that its area is minimized.

[0153] Thus, the tire 1 can further effectively suppress unintended exposure of the colored rubber 22 a in the groove 23 of the protruding portion of the mark display portion 22B.

[0154] More preferably, the groove 23 having a concave bottom inside the outer edge H of the portion F of the mark display portion 22B that is visually recognized as a mark has its groove bottom disposed axially outward from the contour line 24 of the sidewall 20 .

[0155] This can suppress unintended exposure of the colored rubber 22a in the mark display portion 22B. In addition, the inner periphery formed by the inner frame 27 of the mark display portion 22B can be clearly seen.

[0156] According to the tire 1 according to the second embodiment described above, the same effects as (1) to (8) described in the first embodiment are achieved.

[0157] Although specific embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and modifications and improvements made within the scope of achieving the object of the present invention are also included in the scope of the present invention.

[0158] The structure according to the embodiment can be applied to pneumatic tires for various vehicles such as light trucks, trucks, and buses in addition to pneumatic tires for passenger vehicles including light vehicles and SUVs.

Claims

1. A pneumatic tire comprising: a pair of beads having a bead core; a pair of sidewalls extending from the pair of beads toward outer sides in the tire radial direction, respectively; and a tread disposed between the pair of sidewalls, in, The sidewall has a marking display portion, the marking display portion including a protrusion that protrudes from the contour line of the sidewall toward the outer side of the tire axial direction in a cross-sectional view of the tire meridian plane. The badge display unit comprises: Cover rubber; and a colored rubber, which is covered by the cover rubber and at least a portion of which is exposed on the surface, The insignia display portion has a depression in a cross-sectional view of the tire meridian plane. The bottom of the depression is arranged on the outside in the tire axial direction relative to the contour line of the sidewall.

2. The pneumatic tire according to claim 1, wherein: In the tire side view, that is, the main view of the logo display portion, the relationship between the logo display portion area (D) formed by the outline of the logo display portion and the minimum quadrilateral area (E) is: The area of ​​the logo display (D) ÷ the area of ​​the smallest quadrilateral (E) ≥ 70% The minimum quadrilateral is a quadrilateral circumscribing the outline of the emblem display portion and is formed so that its area becomes the minimum.

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. The pneumatic tire according to claim 1, wherein: The length of the depression depth (B) of the depression is a length that is not more than 80% of the protruding height of the emblem display portion protruding from the contour line of the sidewall.

5. The pneumatic tire according to claim 4, wherein: The length of the depression depth (B) of the depression is a length that is 50% or more of the protruding height of the emblem display portion protruding from the contour line of the sidewall.

6. The pneumatic tire according to claim 1, wherein: A protruding height of the emblem display portion protruding from the outline of the sidewall is 1.0 mm or more and 3.0 mm or less.

7. The pneumatic tire according to claim 1, wherein: The length of the indicia display portion in the tire radial direction is not less than 15 mm and not more than 25 mm.

8. The pneumatic tire according to claim 1, wherein: The tire section height is less than 155mm.

9. The pneumatic tire according to claim 1, wherein: The tire section height is less than 130mm.

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

11. The pneumatic tire according to any one of claims 1 to 8, wherein: The depressions are dimples.

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