tire

Abstract

To provide a tire that achieves both peel resistance of sound-absorbing material and vulcanization failure resistance of the tire. [Solution] This tire comprises a pair of bead cores, a carcass layer spanning the pair of bead cores, a pair of cross belts arranged radially outward from the carcass layer, a release agent coating layer formed on the inner surface of the tire, and a sound-absorbing material 20 arranged on the inner surface of the tire. The sound-absorbing material 20 is positioned between a pair of straight lines and attached to the inner surface of the tire. The tire also comprises a plurality of ridges 21, 22 formed on the inner surface of the tire and extending in the width direction of the tire. Furthermore, the maximum value Pc_max of the pitch length Pc of the plurality of ridges 21 in the mounting area Rc of the sound-absorbing material 20 is in the range of 1.50 ≤ Pc_max / Psh_max ≤ 4.00 with respect to the maximum value Psh_max of the pitch length Psh of the plurality of ridges 21, 22 in each of the pair of shoulder areas Rsh, Rsh.

Description

Technical Field

[0001] The present invention relates to a tire, and more particularly to a tire capable of achieving both the peel resistance performance of a sound-absorbing material and the vulcanization failure resistance performance of a tire.

Background Art

[0002] In recent tires, in order to reduce the cavity resonance sound during tire rolling and improve the noise performance of the tire, a technique of providing a sound-absorbing material on the inner surface of the tire has been adopted. Such a sound-absorbing material is attached and installed on the tire after vulcanization molding. As a conventional tire adopting such a structure, the technique described in Patent Document 1 is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the tire provided with the above-described sound-absorbing material, there is a problem of suppressing the peeling of the sound-absorbing material due to repeated deformation during tire rolling. There is also a problem of reducing vulcanization failure during tire vulcanization molding.

[0005] Therefore, the present invention has been made in view of the above, and an object thereof is to provide a tire capable of achieving both the peel resistance performance of a sound-absorbing material and the vulcanization failure resistance performance of a tire.

Means for Solving the Problems

[0006] To achieve the above objective, the tire according to this invention comprises a pair of bead cores, a carcass layer spanning the pair of bead cores, a pair of cross belts arranged radially outside the carcass layer, and a sound-absorbing material arranged on the inner surface of the tire, wherein, in a cross-sectional view in the meridian direction of the tire, a pair of straight lines Le are defined passing through each of the edges of the wide cross belts and perpendicular to the inner surface of the tire, and a pair of shoulder regions are defined as areas of 20% of the belt width Wb2 of the wide cross belts centered on each of the pair of straight lines Le, the sound-absorbing material is arranged between the pair of straight lines Le and attached to the inner surface of the tire, and comprises a plurality of ridges formed on the inner surface of the tire and extending in the width direction of the tire, and the maximum value Pc_max of the pitch length Pc of the plurality of ridges in the mounting region of the sound-absorbing material is in the range of 1.50 ≤ Pc_max / Psh_max ≤ 4.00 with respect to the maximum value Psh_max of the pitch length Psh of the plurality of ridges in each of the pair of shoulder regions. [Effects of the Invention]

[0007] In the tire according to this invention, the pitch length of the ridges in the mounting area of ​​the sound-absorbing material is relatively long, which improves the adhesion of the sound-absorbing material to the inner surface of the tire and suppresses peeling of the sound-absorbing material when the tire rolls. Furthermore, since the pitch length of the ridges in the pair of shoulder areas is relatively short, flexibility of the inner surface of the tire is ensured in areas where the amount of stretch during tire vulcanization molding is large, which suppresses tire vulcanization failure and extends the life of the tire vulcanization bladder. As a result, there is an advantage in achieving both peel resistance of the sound-absorbing material and vulcanization failure resistance of the tire. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a cross-sectional view of a tire in the meridian direction, showing a tire according to an embodiment of this invention. [Figure 2] Figure 2 is a magnified view of the tire shown in Figure 1. [Figure 3] Figure 3 is an enlarged view showing the inner surface of the tire as described in Figure 2. [Figure 4] Figure 4 is a cross-sectional view of the inner surface of the tire as shown in Figure 3, viewed from point A. [Figure 5] Figure 5 is an explanatory diagram showing a modified version of the tire described in Figure 3. [Figure 6] Figure 6 is a diagram showing the results of a performance test of a tire according to an embodiment of this invention. [Modes for carrying out the invention]

[0009] The present invention will be described in detail below with reference to the drawings. However, this embodiment does not limit the present invention. Furthermore, the components of this embodiment include those that are substituted and obvious for substitution while maintaining the identity of the invention. In addition, the various modifications described in this embodiment can be arbitrarily combined within the scope of what is obvious to those skilled in the art.

[0010] [Sound-absorbing tires] Figure 1 is a meridian-direction cross-sectional view of a tire 1 according to an embodiment of this invention. The figure also shows a cross-sectional view of one side region in the radial direction of the tire. In this embodiment, a pneumatic radial tire for passenger cars will be described as an example of a tire.

[0011] In the figure, the tire meridian cross-section is defined as the cross-section obtained when the tire is cut by a plane containing the tire rotation axis (not shown). The tire equatorial plane CL is defined as a plane that passes through the midpoint of the tire cross-sectional width as defined by JATMA and is perpendicular to the tire rotation axis. The tire width direction is defined as the direction parallel to the tire rotation axis, and the tire radial direction is defined as the direction perpendicular to the tire rotation axis. Point T is the tire contact point.

[0012] The tire 1 has an annular structure centered on the tire rotation axis and comprises a pair of bead cores 11, 11, a pair of bead fillers 12, 12, a carcass layer 13, a belt layer 14, a tread rubber 15, a pair of sidewall rubbers 16, 16, a pair of rim cushion rubbers 17, 17, an inner liner 18, and a release agent coating layer 19 (see Figure 1).

[0013] Each pair of bead cores 11, 11 is made by winding one or more bead wires made of steel in a ring-like and multi-layered manner, and is embedded in the bead portion to form the core of the left and right bead portions. Each pair of bead fillers 12, 12 is positioned on the outer circumference of the pair of bead cores 11, 11 in the radial direction of the tire to reinforce the bead portion.

[0014] The carcass layer 13 has a single-layer structure consisting of one carcass ply or a multi-layer structure consisting of multiple carcass plies stacked together, and is stretched in a toroidal manner between the left and right bead cores 11, 11 to form the framework of the tire. The ends of the carcass layer 13 are also wrapped back outward in the tire width direction and secured to enclose the bead cores 11 and bead filler 12. The carcass ply of the carcass layer 13 is constructed by covering multiple carcass cords made of steel or organic fiber material (e.g., aramid, nylon, polyester, rayon, etc.) with a coating rubber and rolling it, and has a cord angle of 80 degrees to 100 degrees (defined as the inclination angle of the carcass cord in the longitudinal direction with respect to the circumferential direction of the tire).

[0015] The belt layer 14 is made up of multiple belt plies 141 to 144 stacked together and arranged around the outer circumference of the carcass layer 13. Each belt ply 141 to 144 includes a pair of cross belts 141 and 142 and a pair of belt covers 143 and 144.

[0016] The pair of crossed belts 141 and 142 are formed by coating a plurality of belt cords made of steel or organic fiber material with coating rubber and subjecting them to rolling processing, and have a cord angle (defined as the inclination angle of the longitudinal direction of the belt cord with respect to the tire circumferential direction) of 15° or more and 55° or less in absolute value. Also, the pair of crossed belts 141 and 142 have cord angles of opposite signs to each other, and the longitudinal directions of the belt cords cross each other and are laminated (a so-called cross ply structure). Further, the pair of crossed belts 141 and 142 are laminated and arranged on the outer side in the tire radial direction of the carcass layer 13.

[0017] The belt covers 143 and 144 are formed by coating belt cover cords made of steel or organic fiber material with coating rubber, and have a cord angle of 0° or more and 10° or less in absolute value. Also, the belt covers 143 and 144 are, for example, strip materials formed by coating one or a plurality of belt cover cords with coating rubber, and this strip material is wound around the outer peripheral surfaces of the crossed belts 141 and 142 a plurality of times in a spiral manner in the tire circumferential direction. Further, the belt covers 143 and 144 are arranged so as to cover the entire area of the crossed belts 141 and 142.

[0018] The tread rubber 15 is arranged on the outer periphery in the tire radial direction of the carcass layer 13 and the belt layer 14 to constitute the tread portion of the tire 1. Also, the tread rubber 15 is made of a rubber material excellent in ground contact characteristics and weather resistance, and is exposed over the entire area of the tire outer peripheral surface to constitute the tread surface. The pair of sidewall rubbers 16 and 16 are respectively arranged on the outer sides in the tire width direction of the carcass layer 13 to constitute the left and right sidewall portions. The pair of rim cushion rubbers 17 and 17 extend from the inner side in the tire radial direction to the outer side in the tire width direction of the left and right bead cores 11 and 11 and the turned-back portion of the carcass layer 13 to constitute the rim fitting surface of the bead portion.

[0019] The inner liner 18 is an air-permeation prevention layer disposed on the inner cavity surface of the tire to cover the carcass layer 13, suppressing oxidation due to the exposure of the carcass layer 13 and preventing leakage of the air filled in the tire. Further, the inner liner 18 may be composed of, for example, a rubber composition mainly composed of butyl rubber, or may be composed of a thermoplastic resin or a thermoplastic elastomer composition in which an elastomer component is blended in the thermoplastic resin.

[0020] The release agent coating layer 19 is a coating layer made of a release agent, which is formed over the entire area of the inner surface of the tire and over the entire area of the inner surface of the inner liner 18. Specifically, the release agent coating layer 19 is formed by the release agent applied to the surface of the tire vulcanization bladder remaining on the inner surface of the tire in the tire vulcanization molding process. Such a release agent is used to facilitate peeling of the tire after vulcanization molding from the tire vulcanization bladder, and is mainly composed of, for example, a silicon component, an inorganic component, a surfactant, etc. In the configuration of FIG. 1, since the release agent coating layer 19 is very thin, the release agent coating layer 19 and the inner liner 18 are shown integrally.

[0021] [Sound-absorbing material] FIG. 2 is an enlarged view showing the tire 1 described in FIG. 1. The figure shows the tread portion of one side region bounded by the tire equatorial plane CL.

[0022] The sound-absorbing material 20 is a component that reduces cavity resonance noise during tire rolling, and is made of, for example, a porous material having open cells. The sound-absorbing material 20 is also placed on the inner surface of the tire and extends around the entire circumference of the tire. For example, in the configuration of Figure 1, the sound-absorbing material 20 has a rectangular cross-sectional shape and is placed in the center region of the tire and crosses the tire equatorial plane CL. The sound-absorbing material 20 is also temporarily fixed to the inner surface of the tire using an adhesive or adhesive sheet and then pressed into place. The width Wa of the sound-absorbing material 20 is in the range of 0.30 ≤ Wa / Wb2 ≤ 0.90 relative to the belt width Wb2 of the wide cross belt 141, and preferably in the range of 0.35 ≤ Wa / Wb2 ≤ 0.85. Furthermore, the sound-absorbing material 20 may consist of a pair of sound-absorbing members that are separated from each other and are placed spaced apart from each other in the tire width direction with the tire equatorial plane CL in between (not shown).

[0023] The width Wa of the sound-absorbing material 20 is defined as the maximum width of the area where the sound-absorbing material 20 is placed on the inner surface of the tire. In the configuration described above, where the sound-absorbing material 20 consists of a pair of sound-absorbing members that are separated from each other, the width Wa of the sound-absorbing material 20 is measured using the outermost edge portion in the tire width direction of the pair of sound-absorbing members as the measurement point.

[0024] The belt width Wb2 of the cross belt 141 is the distance in the tire width direction between the left and right edges of the belt ply (more specifically, the outermost belt cord in the tire width direction), and is measured with the tire mounted on a specified rim, with a specified internal pressure applied, and under no-load conditions.

[0025] The specified rim refers to the "applicable rim" specified by JATMA, the "Design Rim" specified by TRA, or the "Measuring Rim" specified by ETRTO. The specified internal pressure refers to the "maximum air pressure" specified by JATMA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or the "INFLATION PRESSURES" specified by ETRTO. The specified load refers to the "maximum load capacity" specified by JATMA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or the "LOAD CAPACITY" specified by ETRTO. However, in JATMA, for passenger car tires, the specified internal pressure is 180 [kPa] air pressure, and the specified load is 88 [%] of the maximum load capacity.

[0026] In Figure 1, a pair of straight lines Le, Le are defined perpendicular to the inner surface of the tire, passing through each edge of the wide cross belt 141 (see Figure 1). Furthermore, as shown in Figure 2, a pair of shoulder regions Rsh are defined as areas representing 20% ​​of the belt width Wb2 of the wide cross belt 141, preferably 10% of the belt width Wb2, centered on each of the pair of straight lines Le. That is, the areas from the pair of straight lines Le, Le in the inner and outer directions in the tire width direction, respectively, up to 10% of the belt width Wb2, are defined as the pair of shoulder regions Rsh. The pair of shoulder regions Rsh are defined as areas in the tire width direction along the inner surface of the tire.

[0027] Furthermore, as shown in Figure 1, the sound-absorbing material 20 is positioned between a pair of straight lines Le, Le. That is, the sound-absorbing material 20 is positioned in the inner region in the tire width direction, demarcated by the pair of straight lines Le, Le, so as not to intersect the pair of straight lines Le, Le. In this case, it is preferable that the entire sound-absorbing material 20 is positioned in a region of 80% of the belt width Wb2 of the wide intersecting belt 141 centered on the tire equatorial plane CL. That is, it is preferable that the outermost edge portion of the sound-absorbing material 20 in the tire width direction is positioned at a distance of 10% or more of the belt width Wb2 from the edge portion of the wide intersecting belt 141 so as not to intersect the pair of shoulder regions Rsh (see Figure 2). This suppresses peeling of the sound-absorbing material 20 caused by repeated deformation during tire rolling.

[0028] Furthermore, as shown in Figure 2, the sound-absorbing material 20 is attached to the inner surface of the tire via a release agent coating layer 19. Specifically, as shown in Figure 3, the release agent coating layer 19 is formed on the inner surface of the inner liner 18, and the sound-absorbing material 20 is attached to the inner surface of the tire via this release agent coating layer 19. In this case, as described above, the sound-absorbing material 20 may be fixed to the inner surface of the tire using an adhesive, or it may be attached detachably from the inner surface of the tire via an intermediate member such as an engagement sheet having a fastener or hook (not shown).

[0029] Furthermore, Figure 2 defines the mounting area Rc of the sound-absorbing material 20 on the inner surface of the tire. In the configuration shown in Figure 2, as described above, the sound-absorbing material 20 has a rectangular cross-section and is bonded to the inner surface of the tire via a release agent coating layer 19 over the entire area of ​​one side thereof. Therefore, the mounting area Rc of the sound-absorbing material 20 is continuous along the inner surface of the tire. In addition, by having the mounting area Rc of the sound-absorbing material 20 intersect the tire equatorial plane CL, and preferably include a region of 20 [mm] centered on the tire equatorial plane CL, peeling of the sound-absorbing material 20 is effectively suppressed.

[0030] However, the configuration is not limited to this. For example, the sound-absorbing material 20 may consist of a pair of sound-absorbing members that are separated from each other, and may be arranged spaced apart in the tire width direction with the tire equatorial plane CL in between (not shown). In such a configuration, a pair of separated mounting regions Rc are defined.

[0031] [Ridges on the inside of the tire] Figure 3 is an enlarged view showing the inner surface of the tire as described in Figure 2. Figure 4 is a cross-sectional view of the inner surface of the tire as described in Figure 3, viewed from point A. These figures highlight the ridges 21 and 22 formed on the inner surface of the tire.

[0032] As shown in Figure 3, tire 1 is provided with multiple ridges 21 and 22 on its inner surface.

[0033] The ridges 21 and 22 have a rib-like structure formed on the inner surface of the tire and extending in the tire width direction. Furthermore, multiple ridges 21 and 22 are arranged at predetermined intervals in the circumferential direction of the tire and are formed around the entire circumference of the tire. These ridges 21 and 22 are formed by transferring grooves formed on the outer surface of a tire vulcanization bladder to the inner surface of the tire, in order to suppress the discharge of residual air during tire vulcanization molding. Although Figure 3 shows only one region bounded by the tire equatorial plane CL, multiple ridges 21 and 22 are similarly formed in the other region as well (not shown). In this case, the multiple ridges 21 and 22 may be formed point-symmetrically with respect to a point on the tire equatorial plane CL, or they may be formed line-symmetrically with respect to the tire equatorial plane CL.

[0034] Furthermore, the pitch length of the ridges 21 and 22 is set to be shorter in the pair of shoulder regions Rsh, Rsh and longer in the mounting region Rc of the sound-absorbing material 20 located between them. Specifically, as shown in Figure 3, the maximum value Pc_max of the pitch length Pc of the ridge 21 in the mounting region Rc of the sound-absorbing material 20 is in the range of 1.50 ≤ Pc_max / Psh_max ≤ 4.00, and preferably in the range of 1.50 ≤ Pc_max / Psh_max ≤ 3.00, with respect to the maximum value Psh_max of the pitch length Psh of the ridges 21 and 22 in each of the pair of shoulder regions Rsh, Rsh.

[0035] The pitch lengths Pc and Psh are measured as the sequence lengths of adjacent ridges 21, 21;21, 22 in each region Rc and Rsh. In addition, in regions Rc and Rsh where no ridges are located (for example, the region near the tire equatorial plane CL in Figure 3), the ridge pitch length is not defined.

[0036] In the above configuration, the pitch length Pc of the ridges 21 in the mounting area Rc of the sound-absorbing material 20 is relatively long, which improves the adhesion of the sound-absorbing material 20 to the inner surface of the tire and suppresses peeling of the sound-absorbing material 20 when the tire rolls. In addition, the pitch length Psh of the ridges 21 and 22 in the pair of shoulder areas Rsh is relatively short, which ensures flexibility of the inner surface of the tire in areas where the amount of stretch during tire vulcanization molding is large, suppresses tire vulcanization failures, and extends the lifespan of the tire vulcanization bladder.

[0037] Furthermore, the pitch length Pc of the ridges 21 in the mounting area Rc of the sound-absorbing material 20 (see Figure 3) is in the range of 5.0 [mm] ≤ Pc ≤ 20 [mm], preferably in the range of 10 [mm] ≤ Pc ≤ 20 [mm]. The lower limit ensures the peel resistance of the sound-absorbing material 20 due to the long pitch length Pc of the ridges 21. The upper limit ensures the peelability of the tire from the tire vulcanization bladder during tire vulcanization molding. Note that in the configuration of Figure 3, there are no ridges in the region near the tire equatorial plane CL, so the pitch length Pc of the ridges 21 is not defined.

[0038] Furthermore, the pitch length Psh (see Figure 3) of the ridges 21 and 22 in each of the pair of shoulder regions Rsh is in the range of 3.0 [mm] ≤ Psh ≤ 15 [mm], preferably in the range of 5.0 [mm] ≤ Psh ≤ 10 [mm]. The above lower limit ensures the exhaust action of the ridges 21 and 22 during tire vulcanization molding, thereby ensuring the tire's vulcanization failure resistance. The above upper limit ensures the flexibility of the inner surface of the tire during tire vulcanization molding, thereby suppressing tire vulcanization failure.

[0039] For example, in the configuration shown in Figure 3, the multiple ridges 21 and 22 extend in the tire width direction so as not to intersect each other in the shoulder region Rsh and the sound-absorbing material 20 placement region Rc. Furthermore, the multiple ridges 21 and 22 penetrate the shoulder region Rsh in the tire width direction and terminate between the shoulder region Rsh and the tire equatorial plane CL. As a result, the multiple ridges 21 and 22 do not intersect with respect to the tire equatorial plane CL. These features improve the exhaust action of the ridges 21 and 22 during tire vulcanization molding.

[0040] Furthermore, the first ridge 21 terminates at one end within the placement area Rc of the sound-absorbing material 20, extends in the tire width direction, crosses the shoulder area Rsh, and extends to the tire bead. Multiple first ridges 21 are arranged in the circumferential direction of the tire. The second ridge 22 terminates at one end between the placement area Rc of the sound-absorbing material 20 and the shoulder area Rsh, extends in the tire width direction, crosses the shoulder area Rsh, and terminates at the buttress portion of the tire without exceeding the maximum tire width. Therefore, the second ridge 22 does not extend into the placement area Rc of the sound-absorbing material 20. Also, one second ridge 22 is positioned between adjacent first ridges 21, 21. Therefore, in the shoulder region Rsh, the first ridge 21 and the second ridge 22 are arranged alternately in the circumferential direction of the tire, and the pitch length Psh of the first and second ridges 21 and 22 is shorter than the pitch length Pc of the first ridge 21 in the sound-absorbing material 20 arrangement region Rc.

[0041] Furthermore, in the configuration shown in Figure 3, the first and second ridges 21 and 22 are inclined with respect to the tire width direction. Also, the inclination angle θc of ridge 21 with respect to the tire width direction in the mounting area Rc of the sound-absorbing material 20 is equal to the inclination angle θsh of ridge 22 with respect to the tire width direction in the shoulder area Rsh. In addition, the inclination angles θc and θsh of ridges 21 and 22 are in the range of 10 degrees to 35 degrees, preferably in the range of 15 degrees to 30 degrees. This improves the exhaust effect of ridges 21 and 22 during tire vulcanization molding.

[0042] The inclination angles θc and θsh of the ridges 21 and 22 in each region are measured as the angles between the tire width direction and a virtual straight line connecting the ends of the ridges 21 and 22 in each region, viewed in plan on the inner surface of the tire.

[0043] Furthermore, in the configuration shown in Figure 3, the heights H1 and H2 (see Figure 4) of the first and second ridges 21 and 22 are equal and constant along the longitudinal direction of the ridges 21 and 22. Also, the height Hc (not shown) of the ridge 21 in the mounting area Rc of the sound-absorbing material 20 is equal to the height Hsh (not shown) of the ridge 22 in the shoulder area Rsh. In addition, the heights Hc and Hsh of the ridges 21 and 22 are in the range of 0.2 [mm] to 1.5 [mm], preferably in the range of 0.2 [mm] to 1.0 [mm]. This improves the exhaust action of the ridges 21 and 22 during tire vulcanization molding.

[0044] [Differentiation] Figure 5 is an explanatory diagram showing a modified example of tire 1 as described in Figure 3. In this figure, components identical to those described in Figure 3 are denoted by the same reference numerals, and their descriptions are omitted.

[0045] In the configuration shown in Figure 3, as described above, the inclination angle θc of the ridge 21 with respect to the tire width direction in the mounting area Rc of the sound-absorbing material 20 is equal to the inclination angle θsh of the ridge 22 with respect to the tire width direction in the shoulder area Rsh.

[0046] In contrast, in the configuration shown in Figure 5, as described above, the inclination angle θc of the ridge 21 with respect to the tire width direction in the mounting region Rc of the sound-absorbing material 20 is smaller than the inclination angle θsh of the ridges 21 and 22 with respect to the tire width direction in the shoulder region Rsh (θc < θsh), preferably in the range of 5 [deg] ≤ θsh - θc ≤ 20 [deg]. This configuration is preferable in that, in the mounting region Rc of the sound-absorbing material 20, the progression of peeling of the sound-absorbing material 20 from the inner surface of the tire is suppressed, and in the shoulder region Rsh, the exhaust effect of the ridges 21 and 22 during tire vulcanization molding is enhanced.

[0047] In addition, in the configuration of FIG. 4, the height Hc (not shown) of the ridge 21 in the attachment region Rc of the sound-absorbing material 20 is equal to the height Hsh (not shown) of the ridge 22 in the shoulder region Rsh, as described above.

[0048] However, it is not limited to this, and the maximum value Hc_max of the height Hc of the ridge 21 in the attachment region Rc of the sound-absorbing material 20 may be smaller than the maximum value Hsh_max of the height Hs of the ridges 21 and 22 in the shoulder region Rsh (Hc_max < Hsh_max). Preferably, it is in the range of 0.2 [mm] ≤ Hsh - Hc. Thereby, in the attachment region Rc of the sound-absorbing material 20, the adhesion of the sound-absorbing material 20 to the inner surface of the tire is improved, and in the shoulder region Rsh, the exhaust effect of the ridges 21 and 22 during tire vulcanization molding is improved. The above configuration can be realized, for example, by having a structure (not shown) in which the first ridge 21 gradually reduces the height H1 toward the tire equatorial plane CL.

[0049] In addition, uneven portions having a height lower than that of the ridges 21 and 22 may be formed in the regions between the adjacent ridges 21, 21; 21, 22 in FIG. 3 (not shown). Thereby, the exhaust effect of the ridges 21 and 22 during tire vulcanization molding is improved.

[0050] [Tire Manufacturing Method] In the tire manufacturing process, first, each member such as the bead wire constituting the bead core 11, the carcass ply constituting the carcass layer 13, the belt plies 141 to 143 constituting the belt layer 14, the tread rubber 15, the sidewall rubber 16, and the rim cushion rubber 17 (see FIG. 1) is subjected to a molding machine to form a green tire.

[0051] Next, the green tire is mounted and held on the molding surface of the tire vulcanization molding die. At this time, a release agent is applied to the molding surface of the tire vulcanization molding die and the outer surface of the tire vulcanization bladder. At this time, the film thickness Gs' (not shown) of the release agent in the region corresponding to each of at least a pair of shoulder regions Rsh, Rsh is adjusted.

[0052] Next, the green tire is vulcanized. Specifically, the tire vulcanization mold is heated, and the tire vulcanization bladder expands to press the green tire against the molding surface of the mold. As the green tire is heated, the rubber molecules and sulfur molecules in the tread combine, and vulcanization takes place. Then, the molding surface of the tire vulcanization mold is transferred to the green tire, and the tire's tread pattern is formed. After that, the vulcanized tire is removed from the tire vulcanization mold.

[0053] Next, the sound-absorbing material 20 is attached to the tire. Specifically, the sound-absorbing material 20 is temporarily fixed to the inner surface of the tire using adhesive or adhesive tape, and then the sound-absorbing material 2 is pressed against the inner surface of the tire.

[0054] [effect] As described above, [1] the tire 1 comprises a pair of bead cores 11, 11, a carcass layer 13 spanning the pair of bead cores 11, 11, a pair of cross belts 141, 142 positioned radially outward from the carcass layer 13, a release agent coating layer 19 formed on the inner surface of the tire, and a sound-absorbing material 20 positioned on the inner surface of the tire (see Figure 1). In addition, in a cross-sectional view in the meridian direction of the tire, a pair of straight lines Le, Le are defined perpendicular to the inner surface of the tire, passing through each of the edges of the wide cross belt 141. Furthermore, a pair of shoulder regions Rsh, Rsh (see Figure 2) are defined as areas representing 20% ​​of the belt width Wb2 of the wide cross belt 141, centered on each of the pair of straight lines Le, Le. The sound-absorbing material 20 is positioned between the pair of straight lines Le, Le and attached to the inner surface of the tire. The tire 1 also comprises a plurality of ridges 21, 22 formed on the inner surface of the tire and extending in the tire width direction (see Figure 3). Furthermore, the maximum value Pc_max of the pitch length Pc of the multiple ridges 21 in the mounting area Rc of the sound-absorbing material 20 is in the range of 1.50 ≤ Pc_max / Psh_max ≤ 4.00 with respect to the maximum value Psh_max of the pitch length Psh of the multiple ridges 21 and 22 in each of the pair of shoulder areas Rsh.

[0055] In the above configuration, the pitch length Pc of the ridges 21 in the mounting area Rc of the sound-absorbing material 20 is relatively long, improving the adhesion of the sound-absorbing material 20 to the inner surface of the tire and suppressing peeling of the sound-absorbing material 20 during tire rolling. Furthermore, since the pitch length Psh of the ridges 21 and 22 in the pair of shoulder areas Rsh is relatively short, flexibility of the inner surface of the tire is ensured in areas with large stretch amounts during tire vulcanization molding, suppressing tire vulcanization failures and extending the life of the tire vulcanization bladder. This has the advantage of achieving both peel resistance of the sound-absorbing material and vulcanization failure resistance of the tire.

[0056] Furthermore, [2] in this tire 1, the multiple ridges 21 and 22 do not intersect each other in the shoulder region Rsh and the sound-absorbing material 20 placement region Rc (see Figure 3). This has the advantage of improving the exhaust action of the ridges 21 and 22 during tire vulcanization molding.

[0057] Furthermore, [3] in this tire 1, in the tire 1 described in [1] or [2] above, a plurality of ridges 21, 22 include ridges 21, 22 whose ends are on the tire equatorial plane CL side of the shoulder region Rsh (see Figure 3). This has the advantage of improving the exhaust action of the ridges 21, 22 during tire vulcanization molding.

[0058] Furthermore, [4] in this tire 1, in the tire 1 described in any one of [1] to [3] above, the multiple ridges 21, 22 include ridges 21, 22 that penetrate the shoulder region Rsh in the tire width direction (see Figure 3). This has the advantage of improving the exhaust action of the ridges 21, 22 during tire vulcanization molding.

[0059] Also, in this tire 1, among the tires 1 described in any one of [1] to [4] above, the maximum value Hc_max of the heights Hc of the plurality of ridges 21 and 22 in the attachment region Rc of the sound-absorbing material 20 has a relationship of Hc_max < Hsh_max with respect to the maximum value Hsh_max of the heights Hsh of the plurality of ridges 21 and 22 in the pair of shoulder regions Rsh and Rsh (not shown). Thereby, in the attachment region Rc of the sound-absorbing material 20, the adhesion of the sound-absorbing material 20 to the inner surface of the tire is improved, and in the shoulder region Rsh, there is an advantage that the exhaust effect of the ridges 21 and 22 during tire vulcanization molding is improved.

[0060] Also, in this tire 1, among the tires 1 described in any one of [1] to [5] above, the inclination angle θc of the plurality of ridges 21 in the tire width direction in the attachment region Rc of the sound-absorbing material 20 has a relationship of θc < θsh with respect to the inclination angle θsh of the plurality of ridges 21 and 22 in the tire width direction in the pair of shoulder regions Rsh and Rsh (see FIG. 5). In such a configuration, in the attachment region Rc of the sound-absorbing material 20, the progress of peeling of the sound-absorbing material 20 from the inner surface of the tire is suppressed, and in the shoulder region Rsh, there is an advantage that the exhaust effect of the ridges 21 and 22 during tire vulcanization molding is enhanced.

Example

[0061] FIG. 6 is a chart showing the results of a performance test of a tire according to an embodiment of the present invention.

[0062] In this performance test, evaluations were made on a plurality of types of test tires regarding (1) the peel resistance performance of the sound-absorbing material and (2) the resistance to vulcanization failure performance. Also, a test tire of tire size 235 / 45ZR18 98Y was prototyped.

[0063] (1) In evaluating the peel resistance performance of the sound-absorbing material, each test tire was mounted on a wheel with a standard rim specified by JATMA, and a running test was conducted on a drum testing machine under the conditions of a temperature of 20°C, a running speed of 81 km / h, an air pressure of 160 kPa, a load of 5 kN, and a running distance of 6,480 km. After that, the presence or absence of rupture of the sound-absorbing material was visually confirmed. An index evaluation was then performed, with a value of 100 if the amount of detachment and peeling of the sound-absorbing material was between 1 / 8 and 1 / 4 of the total sound-absorbing material. In this evaluation, a higher value indicates less detachment and peeling of the sound-absorbing material, which is preferable.

[0064] (2) In the evaluation of vulcanization failure resistance, the appearance defects on the inner surface of 100 test tires were visually observed and evaluated. This evaluation was performed using an index evaluation with the comparative example as the baseline (100), and a higher value is preferable.

[0065] The test tires of the comparative example and the example have the configuration shown in Figures 1 and 2, and are equipped with a rectangular cross-sectional sound-absorbing material 20 on the inner surface of the tire. The belt width Wb2 of the wide cross belt 141 is 210 [mm], and the width Wa of the sound-absorbing material 20 is 140 [mm]. The height H1 (=Hc) of the first ridge 21 in the placement area Rc of the sound-absorbing material 20 is 0.3 [mm], and the inclination angle θc with respect to the tire width direction is 30 [deg].

[0066] As the test results show, the test tire in this example demonstrates that both the peel resistance of the sound-absorbing material and the vulcanization failure resistance of the tire are achieved. [Explanation of Symbols]

[0067] 1 Tire; 11 Bead core; 12 Bead filler; 13 Carcass layer; 14 Belt layer; 141, 142 Cross belts; 143 Belt cover; 15 Tread rubber; 16 Sidewall rubber; 17 Rim cushion rubber; 18 Inner liner; 19 Release agent coating layer; 20 Sound absorbing material; 21, 22 Ridge

Claims

1. A tire comprising a pair of bead cores, a carcass layer spanning the pair of bead cores, a pair of cross belts arranged radially outward of the carcass layer, and a sound-absorbing material arranged on the inner surface of the tire, In a cross-sectional view along the tire meridian, a pair of straight lines Le are defined that pass through each of the edges of the wide intersecting belt and are perpendicular to the inner surface of the tire. A pair of shoulder regions are defined, each centered on one of the pairs of straight lines Le and representing 20% ​​of the belt width Wb2 of the wide intersecting belt. The sound-absorbing material is placed between the pair of straight lines Le and attached to the inner surface of the tire. It has multiple ridges formed on the inner surface of the tire and extending in the width direction of the tire, and A tire characterized in that the maximum value Pc_max of the pitch length Pc of the plurality of ridges in the mounting area of ​​the sound-absorbing material is in the range of 1.50 ≤ Pc_max / Psh_max ≤ 4.00 with respect to the maximum value Psh_max of the pitch length Psh of the plurality of ridges in each of the pair of shoulder areas.

2. The tire according to claim 1, wherein the plurality of ridges do not intersect each other in the shoulder region and the arrangement region of the sound-absorbing material.

3. The tire according to claim 1, wherein the plurality of ridges include ridges whose ends are on the tire equatorial plane side of the shoulder region.

4. The tire according to claim 1, which includes a plurality of ridges that penetrate the shoulder region in the tire width direction.

5. The tire according to claim 1, wherein the maximum value Hc_max of the heights Hc of the plurality of ridges in the mounting area of ​​the sound-absorbing material has the relationship Hc_max < Hsh_max with respect to the maximum value Hsh_max of the heights Hsh of the plurality of ridges in the pair of shoulder areas.

6. The tire according to claim 1, wherein the inclination angle θc of the plurality of ridges in the mounting area of ​​the sound-absorbing material with respect to the tire width direction is such that θc < θsh with respect to the inclination angle θsh of the plurality of ridges in the pair of shoulder areas with respect to the tire width direction.

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