Tire

Abstract

To provide a tire capable of suppressing noise generated during rolling without deteriorating other performances.SOLUTION: A tire comprising a radial carcass, an inner liner, a belt layer, and a tread rubber layer, wherein a thickness from an outer circumferential surface of the radial carcass to an inner circumferential surface of the inner liner in a crown portion of the tire and a thickness from an outer circumferential surface of the belt layer to an outer circumferential surface of the tread rubber layer in the crown portion include a portion thicker than a thickness in a predetermined range including a center in a tire width direction and a thickness in a range outside the predetermined range, the thick portion in the thickness from the belt layer outer peripheral surface to the tread rubber layer outer peripheral surface in the crown portion is formed by changing only the thickness of the rubber member between the belt layer and the tread rubber layer outer peripheral surface, and the thick portion in the predetermined range in the thickness from the radial carcass outer peripheral surface to the inner liner inner peripheral surface in the crown portion is formed by changing only the thickness of the rubber member between the radial carcass and the inner liner inner peripheral surface.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a tire, and more particularly to a tire that can reduce noise emitted from the tire when it rolls while achieving fuel economy through weight reduction and reduced rolling resistance. [Background technology]

[0002] Conventionally, when a tire is constructed with a thin belt layer in the tread (thin gauge) to reduce the tire's weight and rolling resistance, it is known that when the tire rolls on the road, it deforms in response to the unevenness of the road surface and the unevenness of the tread itself, and this deformation causes vibration in the tread. In particular, when the external bending rigidity of the belt disposed in the tread is low in the width direction, a "higher-order vibration mode" occurs in the cross section of the belt in the width direction. As a technology for suppressing noise generated when the tire rolls, a technology has been proposed in which a thick rubber layer is provided between the belt and carcass ply in the width direction center of the tire (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-201126 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the technology disclosed in Patent Document 1 is applied to a thin-gauge tire, it is likely to affect other tire performance characteristics. For this reason, the arrangement of the rubber layer needs to strike a balance between noise suppression performance and the tire's other performance characteristics without sacrificing them. The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a tire that can suppress noise generated when the tire rolls without degrading other performance required of the tire. [Means for solving the problem]

[0005] A tire configuration for solving the above-described problems includes a radial carcass toroidally disposed between a pair of bead cores, an inner liner disposed with a predetermined thickness on the radially inner side of the radial carcass in the tire radial direction, a belt layer disposed on the radially outer side of the radial carcass, and a tread rubber layer disposed on the radially outer side of the belt layer in the tire radial direction, wherein a thickness from an outer peripheral surface of the radial carcass to an inner peripheral surface of the inner liner in a crown portion of the tire and a thickness from an outer peripheral surface of the belt layer to an outer peripheral surface of the tread rubber layer in the crown portion of the tire are set to a value smaller than the predetermined value. The tire includes a portion that is thicker than a predetermined range including the center in the tire width direction than a thickness in a range outside the predetermined range, and the thick portion in the thickness from the outer peripheral surface of the belt layer in the crown portion of the tire to the outer peripheral surface of the tread rubber layer is formed by changing only the thickness of the rubber member interposed between the belt layer and the outer peripheral surface of the tread rubber layer, and the thick portion in the predetermined range in the thickness from the outer peripheral surface of the radial carcass in the crown portion of the tire to the inner peripheral surface of the inner liner is formed by changing only the thickness of the rubber member interposed between the radial carcass and the inner peripheral surface of the inner liner. According to this configuration, noise generated when the tire is rolling can be suppressed.

[0006] It should be noted that the above summary of the invention does not list all of the necessary features of the present invention, and the individual configurations that make up the group of features can also be inventions. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view of a tire. [Figure 2] FIG. [Figure 3] FIG. 2 is a diagram showing the configuration of a belt layer. [Figure 4] 10A and 10B are diagrams illustrating an example of forming a thick region. [Figure 5] 10A and 10B are diagrams showing other examples of forming thick regions. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present invention will be described in detail below through embodiments of the invention, but the following embodiments do not limit the invention according to the claims, and not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0009] [Basic tire structure] Fig. 1 is a widthwise cross-sectional view of a tire T according to this embodiment. Fig. 2 is an enlarged cross-sectional view of a crown portion. In the following description, the directions indicated by the arrows in the drawings are specified as the tire width direction and the tire (semi)radial direction. The tire width direction is defined as the left and right sides of the paper, with the tire center CL as the center, and the left and right sides of the tire center CL may be referred to as the inner side and the opposite side as the outer side.

[0010] As shown in each drawing, the tire T includes a bead core 12 formed mainly of a cord member, a carcass 14, a belt layer 16, a bead filler 20 formed mainly of a rubber member, a rim cushion rubber 22, a belt under rubber 24, a side rubber 26, a base rubber 28, a tread rubber 30, and an inner liner 32. The bead core 12, the carcass 14, and the belt layer 16 form the skeleton of the tire T, and the inner liner 32, the bead filler 20, the rim cushion rubber 22, the belt under rubber 24, the side rubber 26, the base rubber 28, and the tread rubber 30 are provided as members to add bulk to the skeleton in order to satisfy the performance required for each part of the tire T.

[0011] The bead cores 12, 12, are an assembly of steel cords formed in an annular shape, and are a pair of components spaced apart in the width direction of the tire T. The steel cords forming the bead cores 12 are formed into an annular shape by winding a bead cord formed by, for example, layer-twisting or multi-twisting steel wires a predetermined number of times. The contour shape of the bead cores 12 in a cross-sectional view is, for example, a polygonal shape such as a square or a hexagon, or a circle.

[0012] The carcass 14 is folded back so as to wrap from the inside to the outside of the bead cores 12 provided on the left and right sides, and is provided so as to extend in a toroidal shape between the left and right bead cores 12, 12. The end of the wrapped carcass 14 may terminate radially inward of the maximum width portion of the tire T, radially outward of the tire, or coincident with the maximum width portion. The carcass 14 is formed, for example, by stacking one or more carcass plies. Each carcass ply is formed by arranging fiber cords or steel cords called ply cords in a blind pattern and bonding them to carcass rubber, and is arranged so that the carcass cords extend radially in the tire T.

[0013] The belt layer 16 is wound around the tire circumferential direction at a position corresponding to the tread portion of the tire T, i.e., so as to overlap the outer circumferential side of the crown portion of the carcass 14. This prevents the tread portion of the tire T from protruding due to rotation, and exerts a hoop effect while the vehicle is running.

[0014] The belt layer 16 is composed of, for example, one or more belt plies. As shown in Fig. 3, the belt layer 16 in this embodiment is composed of three overlapping belt plies 17, 18, and 19. Each of the belt plies 17, 18, and 19 is formed as a sheet-like member in which belt cords made of chemical fiber, steel, or the like are arranged in a blind pattern and covered with belt rubber to maintain the arrangement.

[0015] The belt ply 17 and the belt ply 18 are formed so that the belt cords 17A, 18A extend at an angle relative to the tire width direction when arranged on the outer circumferential side of the carcass 14. The belt ply 19 is formed so that the belt cords extend along the tire circumferential direction when arranged on the outer circumferential side of the belt ply 18. Hereinafter, the belt ply 17 and the belt ply 18 will be referred to as inclined belts 17, 18, etc., and the belt ply 19 will be referred to as a circumferential belt 19.

[0016] The inclined belts 17 and 18 are provided overlapping each other so that the belt cords 17A and 18A intersect with each other. The belt cords 17A and 18A constituting the inclined belts 17 and 18 may be made of, for example, steel, and the belt cord constituting the circumferential belt 19 may be made of a material other than steel.

[0017] The angle α17 of the belt cord 17A constituting the inclined belt 17 with respect to the tire width direction and the angle α18 of the belt cord 18A constituting the inclined belt 18 with respect to the tire width direction are preferably set to 60° or more, preferably in the range of 60° to 64°, more preferably in the range of 60° to 62°.

[0018] In this way, it is possible to reduce input from the tread, which causes noise, while ensuring wear resistance and steering stability, by setting the inclination angle of the belt cords 17A:18A of the inclined belts 17;18. Also, by setting a lower limit value for the inclination angle α17;α18 of the belt cords 17A:18A, it is possible to reduce input from the tread, which causes noise, while ensuring wear resistance and steering stability.

[0019] [Tire rubber composition] The bead filler 20 is arranged so as to fill a space formed between the carcass 14 wound around the bead core 12 .

[0020] The rim cushion rubber 22 extends a predetermined length along the outside of the carcass 14 wound up from the innermost part in the tire radial direction of the carcass 14. This protects the adhesion of the tire T to the applicable rim when the tire T is mounted on the rim, and the structure of the bead portion.

[0021] The belt under-rubber 24 is provided between the end side of the belt layer 16 located on the outer side in the tire width direction and the carcass 14, and protects the structure of the end side of the belt layer 16.

[0022] The side rubber 26 is adjacent to the rim cushion rubber 22 and extends radially outward along the outer periphery of the carcass 14 to cover the sides of the belt under rubber 24 .

[0023] The base rubber 28 forms a tread rubber layer together with the tread rubber 30. The base rubber 28 extends in the tire width direction on the outer side of the belt layer 16 in the tire radial direction, and is provided so as to cover the left and right belt under rubbers 24 and the side rubbers 26.

[0024] The tread rubber 30 is provided overlapping the radially outer side of the base rubber 28, and together with the base rubber 28 constitutes the tread portion of the tire T. A predetermined tread pattern is formed in the tread rubber 30, and its surface becomes the contact surface of the tire T.

[0025] The tread rubber 30 is formed with a plurality of circumferential main grooves extending in the tire circumferential direction. For example, as shown in FIG. 1 and elsewhere, one of the plurality of circumferential main grooves, circumferential main groove 31A, may be formed so as to be located in the center of the tire width direction (so as to include the tire center CL). Alternatively, although not shown, two or more circumferential main grooves may be provided in the center region, for example, two or more circumferential main grooves on both sides of the tire center CL. Note that the circumferential main groove 31A is, for example, a recessed portion in which a wear indicator indicating the service life limit of the tire T is set, and refers to the deepest recessed portion among the recessed portions formed in the tire T. Furthermore, the center region refers to at least a range of 25 to 75% of the tread width, with the center of the tread width at least being the 50% position. For example, in the case of a tire with a tread width of 160 mm, this corresponds to a range of 80 mm symmetrically about the tire center CL. Note that, when multiple main grooves are included in the above range, this corresponds to a range covering only the center main groove located closest to the tire center CL. Tread width refers to the distance in the tire width direction between the tread edges when the tire is mounted on an applicable rim, inflated to the specified internal pressure, and under no load. Here, "applicable rim" refers to a rim specified in the industrial standards valid in the region where the tire is produced and used, such as the JATMA (Japan Automobile Tire Manufacturers Association) Year Book in Japan, the ETRTO (European Tire and Rim Technical Organization) Standard Manual in Europe, and the TRA (The Tire and Rim Association Inc.) Year Book in the United States. Furthermore, "specified internal pressure" refers to the air pressure corresponding to the maximum load (maximum load capacity) of a single wheel for the applicable size specified in the specified industrial standards.

[0026] The inner liner 32 extends between the rim cushion rubbers 22, 22 provided on the left and right bead portions, and covers the entire inner periphery of the carcass 14. The inner liner 32 provides airtightness to the pneumatic tire.

[0027] [Change in thickness (rubber thickness) from the inner surface of the carcass to the inner surface of the inner liner] 4(a) to 4(c) are diagrams showing a number of examples of thick-walled regions according to this embodiment, in which the gray parts in each diagram indicate the parts that form the thick-walled regions. 4, in a cross-sectional view in the tire width direction, the tire T is formed so that a thickness t from the outer peripheral surface 14a of the carcass 14 to the inner peripheral surface 32a of the inner liner 32 is thicker in a predetermined range including at least the center in the tire width direction of the crown portion of the tire T than in other portions. Hereinafter, this predetermined range will be referred to as a thick region 40. Note that the thickness t in the thick region 40 does not need to be uniform along the width direction, considering that the tire is a molded rubber product.

[0028] As shown in Figure 4(a), the thick region 40 may be configured, for example, by interposing a rubber member 34 formed in a sheet shape as a separate member between the carcass 14 and the inner liner 32 (hereinafter referred to as interlayer rubber).Also, as shown in Figures 4(b) and 4(c), the thick region 40 may be formed by directly changing the thickness of the carcass rubber forming the carcass 14 or the rubber member forming the inner liner 32, without interposing a separate member.

[0029] Forming the thick region 40 by interposing the interlayer rubber 34 has the advantage of being able to use a rubber material with different properties from the carcass rubber and the inner liner 32. That is, by setting the tan δ of the interlayer rubber 34 to be larger or smaller than the tan δ of the carcass rubber and the inner liner 32, it is possible to change the mass distribution in the tire T and suppress vibration while maintaining other properties required of the tire T. For example, by using rubber with a high hardness as the interlayer rubber 34, vibration in the center portion in the tire width direction can be reduced, and noise performance can be improved.

[0030] Furthermore, when it is necessary to increase the thickness of the thick region 40, to widen the range in the tire width direction, or to do both to improve noise performance, the thick region 40 can be formed by adjusting the thickness of the carcass rubber that forms the carcass 14 or the rubber that forms the inner liner 32, thereby changing the mass distribution in the tire T, suppressing vibration, and improving noise performance.

[0031] The width W40 of the thick region 40 is preferably set to a width that includes at least the entire circumferential main groove 31A formed in the center of the tread portion in the tire width direction. As described above, when the belt layer 16 is configured so that the thickness of the tread portion of a tire is thin, structural vibrations are likely to occur at the tire center CL. In particular, when a circumferential main groove 31A is formed on the tire center CL, the thickness is thin in the tread portion, and vibrations are more likely to be amplified. Therefore, by forming the thick region 40 so that it includes the tire center CL, vibrations caused by the structure can be suppressed. This effectiveness is particularly pronounced when the circumferential main groove 31A is formed on the tire center CL. Furthermore, as described above, when two or more circumferential main grooves are provided on both sides of the tire center CL in the center region of the tread portion, the width of the thick region 40 may be set to include all of the circumferential main grooves formed in the center region, or may be set to correspond to each of the circumferential main grooves.

[0032] 5 is a diagram showing another example of forming a thick region. In order to improve noise performance, if a wide width or thickness is required for the thick region 40 and, for example, forming the thick region 40 is expected to significantly increase the weight of the tire T, it is advisable to narrow the width or reduce the thickness of the thick region 40 on the inner liner 32 side, and additionally form a thick region 50 so that, for example, the thickness u from the outer peripheral surface 16a of the belt layer 16 in the crown portion of the tire T to the outer peripheral surface 30a of the tread rubber layer includes a portion that is thicker than the thickness in a predetermined range including at least the center in the tire width direction than in a range outside the predetermined range.

[0033] In this way, to form the thick region 50 including a portion where the thickness u from the outer peripheral surface 16a of the belt layer 16 to the outer peripheral surface 30a of the tread rubber layer is thicker than the thickness u in a range outside a predetermined range including at least the center in the tire width direction, a method similar to that for forming the thick region 40 can be used. That is, as shown in Fig. 5(a), a rubber member 38 formed in a sheet shape as a separate member may be interposed between the belt layer 16 and the base rubber 28, or as shown in Fig. 5(b), a change in thickness may be directly imparted by the rubber member constituting the base rubber 28.

[0034] In this way, by providing the thick regions 40, 50 on the inner liner 32 side and the tread rubber 30 side, sandwiching the carcass 14 and the belt layer 16 laminated thereon, the rigidity of the carcass 14 and the belt layer 16 of the tire frame members in the tread portion is improved, and therefore the widths W40, W50 of the thick regions 40, 50 formed on the inner liner 32 side and the tread rubber 30 side, respectively, can be narrowed or thinned. Therefore, it is possible to realize a more preferable ground contact shape while suppressing an increase in the weight of the tire T. As a result, the noise performance of the tire T can be improved while ensuring the wear resistance and handling stability.

[0035] As described above, by configuring the thickness from the outer peripheral surface of the radial carcass in the crown portion of the tire T to include a portion that is thicker than the thickness in a range outside of a predetermined range including at least the center in the tire width direction, it is possible to reduce the amplitude of noise in a frequency range that is a structural vibration band while ensuring wear and handling performance, thereby improving noise performance. Furthermore, compared to a case where thickness changes are provided only between the tread rubber layer and the belt layer or between the belt layer and the carcass, it is possible to significantly reduce the amplitude of noise, particularly in a high-frequency range that is a slip band during tire rotation. In addition to the above configuration, the thickness from the outer peripheral surface of the belt layer in the crown portion of the tire to the outer peripheral surface of the tread rubber layer is configured to include a portion that is thicker than the thickness in a range outside of a predetermined range that includes at least the center in the tire width direction, thereby sandwiching the belt layer and carcass, which are tire frame members, and thereby improving noise performance while ensuring wear resistance and handling stability. Furthermore, by forming main grooves on the tread surface of the tread rubber layer within a predetermined range including the center in the tire width direction, noise can be effectively reduced. Furthermore, by configuring the tire to include an inclined belt formed by rubber-coating a plurality of cords that extend in a belt layer at an angle with respect to the tire width direction, and a circumferential belt that is disposed radially outside the inclined belt layer and is formed by rubber-coating a plurality of cords that extend in the tire circumferential direction, it is possible to improve noise performance while maintaining the tire's weight reduction and rolling resistance performance. [Explanation of symbols]

[0036] 12 bead core, 14 carcass, 16 belt layer, 28 base rubber, 30 tread rubber, 32 inner liner, 34 interlayer rubber, CL Tire Center, T Tire.

Claims

1. a radial carcass toroidally disposed between a pair of bead cores; an inner liner having a predetermined thickness and disposed on the tire radial direction inner side of the radial carcass; a belt layer disposed on the outer side of the radial carcass in the tire radial direction; a tread rubber layer disposed radially outward of the belt layer; A tire comprising: a thickness from the outer peripheral surface of the radial carcass to the inner peripheral surface of the inner liner in a crown portion of the tire; and a thickness from the outer peripheral surface of the belt layer to the outer peripheral surface of the tread rubber layer in the crown portion of the tire, a portion having a thickness greater than a predetermined range including the center in the tire width direction and a thickness greater than a thickness in a range other than the predetermined range; a thick portion in a crown portion of the tire from an outer peripheral surface of the belt layer to an outer peripheral surface of the tread rubber layer is formed by changing only the thickness of a rubber member interposed between the belt layer and the outer peripheral surface of the tread rubber layer, A tire characterized in that the thick portion within the specified range in the thickness from the outer peripheral surface of the radial carcass to the inner peripheral surface of the inner liner in the crown portion of the tire is formed by changing only the thickness of the rubber member interposed between the radial carcass and the inner peripheral surface of the inner liner.

2. The rubber member interposed between the belt layer and the outer peripheral surface of the tread rubber layer is 2. The tire according to claim 1, wherein a rubber material having different properties from the rubber constituting the belt layer and the rubber constituting the tread rubber layer is used.

3. The rubber member interposed between the radial carcass and the inner circumferential surface of the inner liner is 3. The tire according to claim 1, wherein a rubber material having properties different from those of the rubber constituting the radial carcass and the rubber constituting the inner liner is used.

4. the tread rubber layer has a main groove on a tread surface within the predetermined range including the center in the tire width direction, The thick portion is When the main groove is formed on the center in the tire width direction, the tread groove is provided at the position where the main groove is formed, The tire according to claim 1, characterized in that, when two or more circumferential main grooves are provided on both sides of the tire width center in a range of 25 to 75% of the tread width when the tire width center is considered to be the 50% position in the tire width direction, the main grooves include all of the circumferential main grooves, or are provided at each position where each main groove is formed.

5. the belt layer is an inclined belt formed by rubber-coating a plurality of cords extending inclined with respect to the tire width direction; a circumferential belt disposed radially outward of the inclined belt layer and including a plurality of rubber-coated cords extending in the circumferential direction of the tire; 2. The tire of claim 1, comprising:

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