Pneumatic tire and tire vulcanization mold

Abstract

The invention provides a pneumatic tire and a tire vulcanization mold, which can reduce noise caused by grooves in a tread surface and improve poor road driving performance. A pneumatic tire is provided with a main groove (7) provided in a tread surface (3f). The main groove (7) includes a concave-convex region (70) between a groove edge (74) of the main groove (7) and a groove bottom surface (71) of the main groove (7). In the concave-convex region (70), the protrusions (10) are arranged in the groove length direction and the groove depth direction. The protrusion (10) has: a rising surface (11) rising from a groove wall surface (72) of the main groove (7) and facing the groove length direction; and an inclined top surface (12) extending in the groove length direction and having a protruding height gradually decreasing with respect to the groove wall surface (72).

Description

Technical Field

[0001] The present disclosure relates to a pneumatic tire and a tire vulcanization mold for vulcanization molding of the pneumatic tire. Background Art

[0002] Patent Documents 1 and 2 each describe a pneumatic tire with multiple microprotrusions formed on the groove walls of the tread surface to reduce noise such as columnar resonance and pumping noise generated by the grooves. Furthermore, while the pneumatic tire described in Patent Document 2 claims improved muddy performance, the microprotrusions are shaped only as truncated cones, cylinders, and prisms, suggesting that there is room for improvement in performance on difficult roads such as muddy terrain.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2022-96534

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2022-128121 Summary of the Invention

[0007] The present disclosure has been made in view of the above-mentioned actual situation, and an object thereof is to provide a pneumatic tire and a tire vulcanization mold that can reduce noise caused by grooves on the tread surface and improve poor road performance.

[0008] The pneumatic tire disclosed herein has a groove arranged on the tread surface, and the groove includes a concave-convex area between the groove edge and the groove bottom surface of the groove. In the concave-convex area, protrusions are arranged along the groove length direction and the groove depth direction. The protrusions have: a rising surface, which rises from the groove wall surface of the groove and faces the groove length direction; and an inclined top surface, whose protruding height relative to the groove wall surface gradually decreases and extends along the groove length direction.

[0009] The tire vulcanization mold disclosed herein includes a protrusion for molding a groove provided on the tread surface of the tire. The protrusion includes a concave-convex region between a concave corner edge corresponding to the groove edge of the groove and a top surface corresponding to the groove bottom surface of the groove. In the concave-convex region, recesses are arranged along the groove length direction and the groove depth direction. The recesses include: a recessed surface that is recessed from the side wall surface of the protrusion and faces the groove length direction; and an inclined bottom surface that has a recessed depth gradually decreasing relative to the side wall surface and extends along the groove length direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a tire meridian cross-sectional view showing an example of a pneumatic tire according to the present embodiment.

[0011] Figure 2 It is a planar development view showing an example of a tread pattern.

[0012] Figure 3 This is a tire meridian cross-section view of the main groove.

[0013] Figure 4 This is a diagram showing the main groove wall surface as viewed from the front.

[0014] Figure 5 (A) is a three-dimensional view of the protrusion. Figure 5 (B) is the AA cross-sectional view.

[0015] Figure 6 It is a three-dimensional diagram of the protrusion.

[0016] Figure 7 is an enlarged view showing three protrusion columns included in the concavo-convex region.

[0017] Figure 8 This is a front view of the groove wall surface of the main groove of the modified example.

[0018] Figure 9 This is a front view of the groove wall surface of the main groove of the modified example.

[0019] Figure 10 It is a planar development view showing an example of a tread pattern.

[0020] Figure 11 This is a tire meridian cross-sectional view showing an example of a tire vulcanization mold according to the present embodiment.

[0021] Figure 12 This is a tire meridian cross-sectional view of the protrusion.

[0022] Figure 13 (A) is a view of the side wall of the protrusion viewed from the front. Figure 13 (B) is the XX cross-sectional view.

[0023] Description of Reference Numerals

[0024] 1…bead portion; 2…sidewall portion; 3…tread portion; 3f…tread surface; 7…main groove; 8…lateral groove; 9…protrusion; 10…protrusion; 11…rising surface; 12…inclined top surface; 21…recessed surface; 22…inclined bottom surface; 70…concave-convex area; 71…groove bottom surface; 72…groove wall surface; 73…connecting surface; 74…groove edge; 90…concave-convex area; 91…top surface; 92…sidewall surface; 94…concave corner edge; C10…protrusion row; Ef…end of feather; Er…rear end of feather. DETAILED DESCRIPTION

[0025] Hereinafter, one embodiment of the present disclosure will be described with reference to the drawings.

[0026] Figure 1 This is a tire meridian cross-sectional view showing an example of a pneumatic tire T according to this embodiment. The pneumatic tire T is a pneumatic tire for automobiles and includes: a pair of bead portions 1; a pair of sidewall portions 2 extending radially outward from the bead portions 1; and a tread portion 3 connected to the radially outer ends of each of the sidewall portions 2. A tread pattern adapted to the required tire performance and usage conditions is formed on a tread surface 3f constituting the outer circumference of the tread portion 3.

[0027] Here, a tire meridian cross section is a cross section cut along a plane including the central axis (tire rotation axis) of the tire T. The tire radial direction is a direction along the diameter of the tire T. The side closer to the central axis of the tire T is the tire radial inner side, and the side farther from the central axis of the tire T is the tire radial outer side. The tire width direction is a direction parallel to the central axis of the tire T. The side closer to the tire equator TC located at the center of the tire T in the tire width direction is the tire width direction inner side, and the side farther from the tire equator TC is the tire width direction outer side. The tire circumferential direction is a direction surrounding the central axis of the tire T.

[0028] An annular bead core 1a and a bead filler 1b are embedded in the bead portion 1. The bead core 1a is formed from a bundle of rubber-coated steel wires. The bead filler 1b is formed from rubber with a substantially triangular cross-section and is located radially outward of the bead core 1a.

[0029] The carcass layer 4 is arranged in a toroidal shape between the pair of bead portions 1. The ends of the carcass layer 4 are wound up so as to sandwich the bead core 1a and the bead outer rubber 1b. The carcass layer 4 is composed of a carcass cord fabric formed by covering a carcass cord extending approximately at right angles to the tire circumference with rubber. As the carcass cord, organic fiber cords such as polyester, rayon, nylon, and aramid are preferably used. The belt layer 5 is stacked on the tire radially outer side of the carcass layer 4, and the belt reinforcement layer 6 is stacked on the tire radially outer side of the belt layer 5.

[0030] The belt layer 5 is composed of multiple (two in this embodiment) belt cords. Each belt cord is formed by covering belt cords extending obliquely with respect to the tire circumferential direction with rubber. The belt cords are stacked so that they intersect in opposite directions. Stainless steel cords are preferably used for the belt cords. The belt reinforcement layer 6 is composed of reinforcing cords extending in the tire circumferential direction with rubber. Organic fiber cords such as polyester, rayon, nylon, and aramid are preferably used as the reinforcing cords.

[0031] Figure 2This is a planar development diagram showing an example of a tread pattern formed on the tread surface 3f. The tire T includes a main groove 7 extending along the tread surface 3f in the tire circumferential direction. While the main groove 7 extends in a straight line, this is not limited to this configuration. For example, the main groove 7 may include a portion inclined at an angle of 5 degrees or less relative to the tire circumferential direction. Thus, a zigzag groove extending in the tire circumferential direction may also be provided. In the case of a zigzag groove, it preferably includes a see-through area (an area that is not obscured by the groove wall surface 72 of the main groove 7 when viewed in the tire circumferential direction and is visible through the groove).

[0032] Figure 3 It is a tire meridian cross-sectional view of the main groove 7. Figure 4 This is a diagram showing the groove wall surface 72 of the main groove 7 as viewed from the front. Figure 5 (A) is a three-dimensional view of the protrusion 10 described later. Figure 5 (B) is a cross-sectional view taken along line AA. The shapes of the cross sections BB and CC are the same as those of the cross section AA, and therefore are omitted from the illustration. Figure 6 1 is a perspective view of the protrusion 10. The structure of the main groove 7 described below can be applied to any one of the plurality of main grooves 7 provided on the tread surface 3f, or can be applied to all of the main grooves 7.

[0033] like Figure 2 As shown, in this embodiment, a tread pattern is employed that is symmetrical about the tire equator TC. This tread pattern is a so-called block pattern, but is not limited thereto. The tire T includes main grooves 7 and lateral grooves 8, which are grooves provided on the tread surface 3f. The main grooves 7 extend continuously in the tire circumferential direction, while the lateral grooves 8 extend in a direction intersecting the main grooves 7.

[0034] The pneumatic tire T in this embodiment is a rotation-direction-specified tire with a designated rotational direction. For example, the rotational direction is specified using markings on the outer surface of the sidewall portion 2. Arrow RD1 indicates the forward side of the tire in the rotational direction, corresponding to the "step-in side" (the side that first contacts the ground when the vehicle is moving forward). Arrow RD2 indicates the rearward side of the tire in the rotational direction, corresponding to the "step-out side" (the side that later contacts the ground when the vehicle is moving forward).

[0035] like Figure 3 and Figure 4As shown, the main groove 7 has: a groove bottom surface 71; and a pair of groove wall surfaces 72, which extend from the groove bottom surface 71 to the outside in the tire radial direction. The groove bottom surface 71 includes a connecting surface 73 with a circular arc cross section that is smoothly connected to the groove wall surface 72. The curvature radius R of the connecting surface 73 is, for example, 1.5 to 2.75 mm. In this embodiment, the groove wall surface 72 extends in a straight line between the groove edge 74 formed by the tread surface 3f and the groove wall surface 72 and the tire radial outer end 75 of the connecting surface 73. The groove width W7 of the main groove 7 in the tire width direction is, for example, 4.0 mm or more, preferably 6.0 mm or more. The groove depth D7 of the main groove 7 in the tire radial direction is, for example, 4.0 mm or more, preferably 6.0 mm or more.

[0036] The main groove 7 includes a concave-convex region 70 between the groove edge 74 and the groove bottom 71 of the main groove 7. The concave-convex region 70 only needs to be formed on at least one groove wall surface 72, but is preferably formed on a pair of groove wall surfaces 72, as in the present embodiment. Preferably, the concave-convex region 70 is not formed on the groove bottom 71. In the concave-convex region 70, the protrusions 10 are arranged along the groove length and groove depth directions. Figure 4 The left-right direction and the up-down direction in φ correspond to the groove length direction (the tire circumferential direction in the case of the main groove 7) and the groove depth direction (the tire radial direction), respectively.

[0037] The protrusions 10 have a rising surface 11 that rises from the groove wall 72 and extends along the groove length; and an inclined top surface 12 that gradually decreases in height relative to the groove wall 72 and extends along the groove length. This configuration allows the protrusions 10 arranged in the concave-convex region 70 to diffusely reflect sound generated within the groove, thereby reducing noise such as air column resonance and pumping noise generated by the grooves on the tread surface 3f. Furthermore, the presence of the rising surface 11 and the inclined top surface 12 facilitates traction against mud and other debris that enters the groove, improving driving performance on difficult roads such as muddy terrain.

[0038] The protrusion 10 protrudes inwardly across the groove width (toward the center of the groove). The protrusion 10's protrusion height relative to the groove wall 72 is greatest at the upper end of the rising surface 11 and decreases as it moves away from the rising surface 11. To minimize resistance to air and water flowing within the main groove 7, the protrusion 10's protrusion height H10 (maximum height) relative to the groove wall 72 is preferably 0.5 mm or less. Furthermore, to ensure the aforementioned noise reduction effect, the protrusion height H10 is preferably 0.1 mm or greater.

[0039] When the protrusion height H10 of the protrusion 10 is relatively small, such as about 0.1 to 0.5 mm, the undulation of the rough surface of the concave-convex area 70 is moderately reduced, thereby helping to suppress the air resistance in the main groove 7 during driving and improve fuel consumption performance. This is because when the air flowing inside the main groove 7 contacts the concave-convex area 70 during driving, a smaller vortex is generated at the top of the protrusion 10, which suppresses the separation of the air or causes the air to separate at a further rear position, thereby reducing the pressure resistance. In view of appropriately exerting the above-mentioned effect, the arrangement pitch P10r of the protrusions 10 in the groove length direction (refer to Figure 7 ) is preferably 2 to 8 times, more preferably 2 to 6 times, the protrusion height H10.

[0040] The length L10 of the protrusions 10 along the groove length is preferably greater than the protrusion height H10. For example, the length L10 is set to 0.8 mm or greater. To ensure the number of protrusions 10 aligned along the groove length, the length L10 is preferably 2.8 mm or less. In the concave-convex region 70, preferably four or more, and more preferably six or more, protrusions 10 are aligned along the groove length.

[0041] It is preferred that the length D10 of the protrusion 10 in the groove depth direction is greater than the protrusion height H10. The length D10 is set to be, for example, 1.0 mm or more. From the perspective of ensuring the number of protrusions 10 arranged in the groove depth direction, the length D10 is preferably 3.0 mm or less. In the concave-convex area 70, preferably 4 or more, more preferably 6 or more, protrusions 10 are arranged in the groove depth direction. In this embodiment, the length D10 is set to be equal to Figure 5 The length E10 and the length F10 are shown to be the same size, but are not limited to this.

[0042] The angle θ11 of the rising surface 11 relative to the groove wall surface 72 is set, for example, to be 80 degrees or greater. Considering the ease of demolding the tire T from the mold during vulcanization molding, the angle θ11 is preferably 90 degrees or greater, and more preferably exceeds 90 degrees. The angle θ11 is set, for example, to be 110 degrees or less. The inclined top surface 12 extends linearly between one end located at the upper end of the rising surface 11 and the other end where the protrusion height relative to the groove wall surface 72 is substantially zero. The other end of the inclined top surface 12 may be located at a position separated from the groove wall surface 72 by a lower protrusion height than the rising surface 11.

[0043] In addition to the above-mentioned rising surface 11 and inclined top surface 12, the protrusion 10 also has a pair of side wall surfaces 13 rising from the groove wall surface 72 and facing the groove depth direction. The side wall surface 13 is formed into a triangle when viewed from the groove depth direction. In this embodiment, it is arranged at the side end Es of the arrow-shaped feather described later. The angle θ13 of the side wall surface 13 relative to the groove wall surface 72 is set to 80 to 110 degrees, for example. From the perspective of increasing the arrangement density of the protrusions 10 by reducing the interval G10 (the interval between the side wall surfaces 13) between adjacent protrusions 10 in the groove depth direction, the angle θ13 is preferably substantially 90 degrees.

[0044] like Figure 4 and Figure 6 As shown, adjacent protrusions 10 in the groove depth direction are aligned in the direction of their rising surfaces 11. In this example, protrusions 10 are repeatedly arranged in the groove depth direction, each having a rising surface 11 facing one side in the groove length direction and an inclined top surface 12 whose protrusion height gradually decreases toward the other side. This structure improves the traction of the protrusions 10 in a specific direction, thereby contributing to improved driving performance on poor roads. The spacing G10 between adjacent protrusions 10 in the groove depth direction is, for example, 0.05 to 0.3 mm, and in this embodiment, is set to 0.1 mm.

[0045] In the present embodiment, the upright surface 11 faces the kick-out side (the rear side RD2 in the rotation direction). Therefore, the inclined top surface 12 gradually decreases the protruding height toward the step-in side (the front side RD1 in the rotation direction). According to the above structure, when driving on poor road surfaces such as muddy areas and sandy areas, or wet roads such as puddles, the effect of discharge on the kick-out side can be obtained, so it is easy to improve traction. In addition, the protruding height of the protrusion 10 gradually decreases toward the step-in side, which helps to suppress the resistance of air and water flowing inside the main groove 7. Based on the above viewpoint, the angle θ12 of the inclined top surface 12 relative to the groove wall surface 72 is preferably greater than 120 degrees, and more preferably greater than 150 degrees.

[0046] When observing the groove wall surface 72 from the front, the protrusion 10 is formed into a polygon. In the present embodiment, the protrusion 10 is formed into an arrow-feather shape (an example of a polygon), and has a rising surface 11 on the side of the rear end Er of the arrow-feather. According to the protrusion 10 in the above-mentioned arrow-feather shape, the effect of discharging mud and the like by utilizing the rising surface 11 can be improved, and the traction force can be easily exerted, thereby suppressing the resistance of the air and water flowing in the groove. The arrow-feather shape includes: an arrow-feather rear end Er that is recessed in the groove length direction (in the present embodiment, the front side RD1 of the rotation direction); an arrow-feather end Ef that protrudes in this direction; and a pair of side ends Es that extend along the groove length direction in a manner of connecting the above-mentioned arrow-feather rear end Er and the arrow-feather end Ef.

[0047] like Figure 4As shown, in this embodiment, arrow-shaped protrusions with the same direction are arranged in the groove depth direction to form protrusion rows C10. The protrusion rows C10 extend in a zigzag pattern along the groove depth direction. In the concave-convex area 70, the protrusion rows C10 are repeatedly arranged along the groove length direction. Figure 7 1 is an enlarged view showing three protrusion columns C10 included in the concavo-convex region 70 . Figure 7 (A) is Figure 4 In the embodiment shown, Figure 7 (B) and Figure 7 (C) is a modified example thereof. Figure 7 (A) and Figure 7 (B) is an example in which the protrusions 10 adjacent to each other in the groove length direction are aligned in the direction in which the rising surface 11 faces. Figure 7 (C) is an example where this is not the case.

[0048] exist Figure 7 In the example of (A), the protrusion rows C10 adjacent in the groove length direction are arranged with the phase (the phase of the sawtooth) staggered in the groove depth direction. Therefore, a cavity 14 surrounded by the upright surface 11 and the inclined top surface 12 is provided between the protrusion rows C10 adjacent in the groove length direction. According to the above structure, the traction can be improved due to the shearing effect of the soil and the like entering the cavity 14, thereby greatly improving the driving performance on poor roads. In addition, the cavity 14 facing the inclined top surface 12 helps prevent the soil in the cavity 14 from being clogged. In this embodiment, the diamond-shaped cavity 14 is provided by staggering the above phase by half the arrangement pitch P10c of the protrusions 10 in the groove depth direction.

[0049] exist Figure 7 In the example (B), the protrusion rows C10 adjacent to each other in the groove length direction are arranged so that the phases in the groove depth direction (the phases of the saw teeth) are aligned. Therefore, the arrangement pitch P10r of the protrusions 10 in the groove length direction is equal to Figure 7 The example (A) is the same as that of FIG. 1 , but the cavity 14 surrounded by the rising surface 11 and the inclined top surface 12 is not provided. Therefore, it is difficult to obtain the above-mentioned effect of improving traction. Although the above-mentioned structure can also be applied, from the perspective of improving the driving performance on bad roads, it is preferred to Figure 7 As shown in (A), the adjacent protrusion rows C10 are arranged with their phases in the groove depth direction shifted.

[0050] exist Figure 7In the example of (C), the protrusion rows C10 adjacent in the groove length direction are configured so that the directions of the arrow feather shapes are opposite to each other and the phases in the groove depth direction (the phases of the saw teeth) are aligned. Therefore, between the protrusion rows C10 adjacent in the groove length direction, there are provided cavities 15 surrounded by the rising surfaces 11 and cavities 16 surrounded by the inclined top surfaces 12. According to the above structure, the traction can be improved due to the shearing effect of the soil and the like entering the cavity 15, thereby making it possible to improve the driving performance on poor roads. Furthermore, the cavity 15 faces the rising surfaces 11 in both directions of the groove length direction, and therefore, the traction can be improved with respect to either groove length direction.

[0051] To ensure effective reduction of noise such as air column resonance, the length L70 of the concave-convex region 70 along the groove length is preferably at least 50% of the length L72 of the groove wall surface 72 along the groove length, and more preferably at least 80%. When the lateral groove 8 opens into the groove wall surface 72 of the main groove 7, the lengths L70 and L72 are measured for adjacent lateral grooves 8 and lateral grooves 8 in the tire circumferential direction. When the lateral groove 8 does not open into the groove wall surface 72 of the main groove 7, the lengths L70 and L72 are measured for a single circumferential lap of the tire. The length L72 is calculated at the groove edge 74.

[0052] In this embodiment, the outer end 76 of the concave-convex region 70 in the tire radial direction is located at the groove edge 74, while the inner end 77 of the concave-convex region 70 in the tire radial direction is located at the outer end 75 of the connecting surface 73, which has an arc-shaped cross section and connects the groove bottom surface 71 and the groove wall surface 72. This configuration makes it easier to ensure the size of the concave-convex region 70 in the groove depth direction, thereby enhancing the effect of reducing noise such as air column resonance and improving poor road performance. The inner end 77 of the concave-convex region 70 is preferably located at or further outward in the tire radial direction than the outer end 75 of the connecting surface 73.

[0053] exist Figure 8 In the modified example shown, the outer end 76 of the concave-convex region 70 in the tire radial direction is configured to be separated from the groove edge 74 of the main groove 7 in the tire radial direction. According to the above structure, the edge component extending in a straight line along the tire circumference appears at the groove edge 74, thereby improving the edge effect of the main groove 7 in the lateral direction. The separation distance D1 of the outer end 76 from the groove edge 74 is set to 1.0 to 2.0 mm, for example. Figure 7 In the example shown in FIG. 5 , the separation distance D1 is constant along the tire circumferential direction, but the present invention is not limited thereto. For example, the separation distance D1 may be changed so as to decrease as approaching the lateral groove 8.

[0054] exist Figure 9In the illustrated variation, the radially inner end 77 of the concave-convex region 70 is configured to be separated radially outward relative to the radially outer end 75 of the connecting surface 73. The groove bottom 71, which is less likely to come into contact with mud and the like, contributes less to traction. Furthermore, if mud comes into contact with the protrusion 10 near the groove bottom 71, mud clogging may occur. Therefore, it is preferable to keep the inner end 77 away from the groove bottom 71. The separation distance D2 between the inner end 77 and the outer end 75 of the connecting surface 73 is set, for example, to 1.0 to 2.0 mm. Separation distance D2 is not limited to a uniform setting and may vary along the tire circumference. Separation distance D2 may also be set in conjunction with separation distance D1 described above.

[0055] In this embodiment, the pneumatic tire T is shown as an example of a tire with a designated rotation direction, but it is not limited to this and can also be a tire with no designated rotation direction. Figure 10 The tread pattern shown is asymmetric about the tire equator TC. This tread pattern is a so-called rib pattern, but is not limited to this. For tires with no designated rotation direction, when the concave-convex area 70 formed by arranging the arrow-shaped protrusions 10 is applied, it can be considered to be Figure 7 The method shown in (C).

[0056] In this embodiment, the main groove 7 includes the above-mentioned concave-convex area 70, but the lateral groove 8 provided on the tread surface 3f may include the above-mentioned concave-convex area instead of or in addition to it. Figure 8 ) is set to about 50% of the groove depth of the transverse groove 8 (for example, 40 to 60%), the edge effect of the groove edge of the transverse groove 8 can be exerted until the middle stage of wear, and in the stage of functioning as a summer tire thereafter, the poor road driving performance can be improved due to the concave and convex areas of the groove wall surface.

[0057] Figure 11 1 is a tire meridian cross-sectional view of a tire vulcanization mold M for vulcanization molding of a pneumatic tire T. Figure 11 In the figure, a tire T is shown by a dotted line, and the tire T is placed in a mold M with the tire width direction facing the vertical direction. The mold M includes a pair of bead rings Mb, into which the bead portion 1 of the tire T is fitted; a pair of sidewall mold portions Ms, which mold the sidewall portion 2 of the tire T; and a tread mold portion Mt, which molds the tread portion 3 of the tire T.

[0058] The mold M includes a tire molding surface Mf that contacts the outer surface of a tire T placed in the mold M. The tire molding surface Mf includes the inner surfaces of a pair of sidewall mold portions Ms and the inner surface of a tread mold portion Mt. The inner surface of the tread mold portion Mt is provided with a concave and convex surface for forming the tread pattern. The tread mold portion Mt is composed of a plurality of sector-shaped pieces divided in the circumferential direction of the tire, which are gathered together and connected in an annular shape. The mold M is a flexible mold having a tread mold portion Mt with the above-described segmented structure, but is not limited to this. For example, it may also be a two-piece mold with the center portion of the tread mold portion divided into two parts in the vertical direction.

[0059] The mold M includes protrusions for forming grooves provided on the tread surface 3f of the tire T. Specifically, the mold M includes: protrusions 9 for forming the main grooves 7; and protrusions 89 for forming the lateral grooves 8 (see FIG. Figure 13 During vulcanization molding, the tire molding surface Mf including the protrusions 9 and 89 is pressed against the tread surface of the unvulcanized tire, thereby forming a tread pattern including the main grooves 7 and the lateral grooves 8.

[0060] Figure 12 It is a tire meridian cross-sectional view of the protrusion 9 . Figure 13 (A) is a view of the side wall surface 92 of the protrusion 9 as viewed from the front. Figure 13 (B) is the XX cross-sectional view. The shapes of the YY and ZZ sections are the same as those of the XX section, and therefore are omitted from the illustration. The protrusion 9 has: a top surface 91; and a pair of side wall surfaces 92, which extend radially outward from the top surface 91 to the tire. The top surface 91 includes a connecting surface 93 with an arc-shaped cross section that is smoothly connected to the side wall surface 92. The protrusion 9 includes a concave-convex area 90 between a concave corner edge 94 corresponding to the groove edge 74 of the main groove 7 and a top surface 91 corresponding to the groove bottom surface 71 of the main groove 7. In the concave-convex area 90, the recesses 20 are arranged along the groove length direction (the length direction of the protrusion) and the groove depth direction (the protruding direction of the protrusion).

[0061] The recessed portion 20 includes a recessed surface 21 that is recessed from the sidewall surface 92 of the protrusion 9 and extends in the groove length direction, and an inclined bottom surface 22 that gradually decreases in depth relative to the sidewall surface 92 and extends in the groove length direction. The main groove 7 of the pneumatic tire T obtained by vulcanization molding using the mold M described above includes a concave-convex region 70 corresponding to the concave-convex region 90 of the protrusion 9. Furthermore, the protrusions 10 arranged in the concave-convex region 70 include a rising surface 11 corresponding to the recessed surface 21 and an inclined top surface 12 corresponding to the inclined bottom surface 22. For details regarding the preferred dimensions, shapes, and configurations of the protrusion 9 and recessed portion 20, refer to the above description of the main groove 7 and protrusion 10.

[0062] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples of the following aspects.

[0063] [1] The pneumatic tire disclosed herein has a groove provided on the tread surface, wherein the groove includes a concave-convex area between the groove edge and the groove bottom surface of the groove, wherein protrusions are arranged along the groove length direction and the groove depth direction, and the protrusions have: a rising surface, which rises from the groove wall surface of the groove and faces the groove length direction; and an inclined top surface, whose protruding height relative to the groove wall surface gradually decreases and extends along the groove length direction.

[0064] According to the above structure, the protrusions arranged in the concave and convex areas diffusely reflect the sound generated within the grooves, thereby reducing noise caused by the grooves on the tread surface, such as air column resonance and pumping noise. Furthermore, the protrusions have the above-mentioned raised surfaces and inclined top surfaces, which facilitate traction against mud and other debris that enter the grooves, thereby improving driving performance on poor roads such as muddy terrain.

[0065] [2] In the pneumatic tire of [1], the protrusions adjacent to each other in the groove depth direction may be aligned in the direction in which the upright surface faces. This configuration can improve the traction of the protrusions 10 in a predetermined direction, thereby contributing to improved driving performance on poor roads.

[0066] [3] The pneumatic tire of [1] or [2] may be configured such that the upright surface faces the kick-out side when the rotation direction is specified. With this configuration, when the tire is driven on muddy or sandy surfaces or wet surfaces such as puddles, the tire can be discharged on the kick-out side, thereby easily improving traction.

[0067] [4] In the pneumatic tire according to any one of [1] to [3] above, the protrusion may be formed in an arrow-feather shape, with the raised surface at the rear end of the feather. This configuration improves the effect of discharging mud and the like using the raised surface, facilitates traction, and reduces resistance to air and water flowing in the groove.

[0068] [5] Based on the pneumatic tire of [4] above, the following structure can be adopted: the arrow-shaped protrusions with the same direction are arranged in the groove depth direction to form a protrusion row, and the protrusion rows adjacent to each other in the groove length direction are arranged with their phases staggered in the groove depth direction. According to the above structure, a cavity surrounded by the upright surface and the inclined top surface is provided, so that the traction can be improved due to the shearing effect of mud and the like entering the cavity, thereby significantly improving the driving performance on poor roads. In addition, the cavity faces the inclined top surface, which helps prevent the cavity from being clogged with mud.

[0069] [6] Based on the pneumatic tire of [4] above, the following structure may be adopted: the protrusions with the same arrow-shaped orientation are arranged in the groove depth direction to form a protrusion row, and the protrusion rows adjacent to each other in the groove length direction are arranged so that the arrow-shaped orientations are opposite to each other and the phases in the groove depth direction are aligned. According to the above structure, a cavity surrounded by the rising surface is provided, so that the traction can be improved due to the shearing effect of mud and the like entering the cavity, thereby effectively improving the driving performance on poor roads. Furthermore, the cavity faces the rising surface on both sides of the groove length direction, so that the traction can be improved in either groove length direction.

[0070] [7] In the pneumatic tire of any one of [1] to [6] above, the tire may be configured as follows: the outer end of the concave-convex region in the tire radial direction is located at the groove edge, and the inner end of the concave-convex region in the tire radial direction is located at the outer end of the connecting surface having an arc-shaped cross section connecting the groove bottom surface and the groove wall surface, or at a position further outward in the tire radial direction than the connecting surface. According to the above configuration, it is easy to ensure the size of the concave-convex region in the groove depth direction, thereby improving the effect of reducing noise such as air column resonance and improving poor road performance.

[0071] [8] In the pneumatic tire according to any one of [1] to [7] above, the interval between adjacent protrusions in the groove depth direction may be 0.3 mm or less. This configuration contributes to increasing the arrangement density of the protrusions.

[0072] [9] In the pneumatic tire according to any one of [1] to [8] above, the protrusion may have a protrusion height of 0.5 mm or less relative to the groove wall surface. Protrusions having such a height are preferred in terms of suppressing resistance of air or water flowing in the groove.

[0073]

[10] The tire vulcanization mold disclosed herein has a protrusion for molding a groove provided on the tread surface of the tire, wherein the protrusion includes a concave-convex area between a concave corner corresponding to the groove edge of the groove and a top surface corresponding to the groove bottom surface of the groove, wherein the concave portions are arranged along the groove length direction and the groove depth direction in the concave-convex area, and the concave portions have: a concave surface that is concave from the side wall surface of the protrusion and faces the groove length direction; and an inclined bottom surface that gradually decreases in depth relative to the side wall surface and extends along the groove length direction. According to the above structure, a tire can be obtained that can reduce noise caused by the groove on the tread surface and improve poor road performance.

[0074] The pneumatic tire of the present disclosure can be configured similarly to a conventional pneumatic tire except for configuring the grooves on the tread surface as described above, and any conventionally known materials, shapes, structures, manufacturing methods, etc. can be employed.

[0075] The tire vulcanization mold of the present disclosure can be configured similarly to a conventional tire vulcanization mold except for the protrusions for forming the grooves on the tread surface in the above-described manner, and any conventionally known materials, shapes, structures, mechanisms, etc. can be employed.

[0076] Although the embodiments of the present disclosure are described based on the drawings, it should be understood that the specific structure is not limited to the embodiments. The scope of the present disclosure is indicated not only by the description of the above embodiments but also by the claims, and includes all changes within the meaning and scope equivalent to the claims.

[0077] The pneumatic tire and tire vulcanization mold disclosed herein are not limited to any of the aforementioned embodiments, nor are they limited to the aforementioned effects. Various modifications and improvements can be made to the pneumatic tire and tire vulcanization mold disclosed herein without departing from the spirit and scope of the present invention. Furthermore, any combination of the various structures employed in the aforementioned embodiments can be employed.

Claims

1. A pneumatic tire, wherein: The pneumatic tire has grooves provided on the tread surface. The groove includes a concave-convex area between the groove edge and the groove bottom surface of the groove, In the concave-convex area, the protrusions are arranged along the groove length direction and the groove depth direction. The protrusion has a rising surface rising from the groove wall surface of the groove and facing the groove length direction; and an inclined top surface, the protruding height of which relative to the groove wall surface gradually decreases and extends along the groove length direction.

2. The pneumatic tire according to claim 1, wherein The protrusions adjacent to each other in the groove depth direction are arranged to be aligned in the direction in which the rising surface faces.

3. The pneumatic tire according to claim 1, wherein The pneumatic tire specifies a direction of rotation, The rising surface faces the kick-out side.

4. The pneumatic tire according to claim 1, wherein The protrusion is formed in a feather shape and has the rising surface on the rear end side of the feather.

5. The pneumatic tire according to claim 4, wherein The arrow-shaped protrusions with the same direction are arranged in the groove depth direction to form a protrusion row. The protrusion rows adjacent to each other in the groove length direction are arranged with their phases shifted in the groove depth direction.

6. The pneumatic tire according to claim 4, wherein: The arrow-shaped protrusions with the same direction are arranged in the groove depth direction to form a protrusion row. The protrusion rows adjacent to each other in the groove length direction are arranged so that the directions of the arrow-shaped feathers are opposite to each other and the phases in the groove depth direction are aligned.

7. The pneumatic tire according to claim 1, wherein The outer end of the concave-convex region in the tire radial direction is arranged at the groove edge. The inner end of the concavo-convex region in the tire radial direction is located at or further outward in the tire radial direction than the outer end of the connecting surface having an arcuate cross section connecting the groove bottom surface and the groove wall surface.

8. The pneumatic tire according to claim 1, wherein The interval between the adjacent protrusions in the groove depth direction is 0.3 mm or less.

9. The pneumatic tire according to any one of claims 1 to 8, wherein A protrusion height of the protrusion relative to the groove wall surface is 0.5 mm or less.

10. A tire vulcanization mold, wherein: The tire vulcanization mold includes a protrusion for molding a groove provided on the tread surface of the tire. The protrusion includes a concave-convex area between a concave corner edge corresponding to the groove edge of the groove and a top surface corresponding to the groove bottom surface of the groove. In the concave-convex area, the concave portions are arranged along the groove length direction and the groove depth direction. The recess has a recessed surface that is recessed from the side wall surface of the protrusion and extends in the groove length direction; and an inclined bottom surface that has a gradually decreasing recessed depth relative to the side wall surface and extends in the groove length direction.

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