tire

Abstract

To provide a tire that can suppress noise that is generated when the tire is rolled, without deteriorating other performance required for the tire.SOLUTION: A tire comprises: a radial carcass arranged toroidally between a pair of bead cores; an inner liner arranged with a predetermined thickness inside the radial carcass in a tire radial direction; and a tread rubber layer arranged outside the radial carcass in the tire radial direction, and includes a portion where a thickness between an outer peripheral surface of the radial carcass to an inner peripheral surface of the inner line in a crown part of the tire is larger in a range other than a predetermined range than in the predetermined range including at least a center in a tire width direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a tire, and particularly to a tire capable of reducing fuel consumption by weight reduction and rolling resistance reduction, and reducing noise emitted from the tire during rolling.

Background Art

[0002] Conventionally, for the purpose of reducing the weight of a tire and reducing rolling resistance, when the thickness of the tread portion is made thin and the belt layer is configured (thin gauge), when the tire rolls on the road surface, it deforms according to the unevenness of the road surface and the unevenness of the tread surface itself, etc., and it is known that vibrations occur in the tread portion due to this deformation. In particular, when the outer bending rigidity in the width direction plane of the belt disposed in the tread portion is low, "higher order vibration modes" occur in the cross section in the belt width direction. As a technique for suppressing the generated noise during tire rolling, a technique of providing a thick rubber layer between the belt and the carcass ply at the center in the width direction of the tire has been proposed (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the technique shown in Patent Document 1 is applied to a thin gauge tire, it is likely to affect other performances of the tire. Therefore, in arranging the rubber layer, it is necessary to balance with the noise suppression performance without sacrificing other performances of the tire. The present invention has been made in view of the above problems, and an object thereof is to provide a tire capable of suppressing the generated noise during tire rolling without degrading other performances required for the tire.

Means for Solving the Problems

[0005] As a tire configuration to solve the above-mentioned problems, the tire comprises a radial carcass toroidally arranged between a pair of bead cores, an inner liner having a predetermined thickness arranged radially inward of the radial carcass, a belt layer arranged radially outward of the radial carcass, and a tread rubber layer arranged radially outward of the belt layer, wherein 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, and the 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 are ,each Includes a portion that is thicker than the thickness in the area outside the predetermined range, which includes the center in the width direction of the tire. Furthermore, the tread rubber layer has a main groove on the tread surface at the center of the tire width direction within the predetermined range, the thick portion is set to a width that includes the entire main groove formed at the center of the tire width direction, and the thick portion in the 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 is formed by interposing a separate rubber member between the belt layer and the tread rubber layer. This was the structure. This configuration makes it possible to suppress noise generated when the tires are rolling.

[0006] It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention, and each individual configuration constituting the group of features may also constitute an invention. [Brief explanation of the drawing]

[0007] [Figure 1] This is a cross-section of a tire. [Figure 2] This is an enlarged cross-sectional view of the crown. [Figure 3] This is a diagram showing the structure of the belt layer. [Figure 4] This figure shows an example of the formation of a thickened region. [Figure 5] This figure shows other examples of the formation of thick-walled regions. [Modes for carrying out the invention]

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

[0009] [Basic structure of tires] Figure 1 is a cross-sectional view of the tire T in the width direction according to this embodiment. Figure 2 is an enlarged cross-sectional view of the crown portion. In the following description, the directions indicated by the arrows in the figures are identified as the tire width direction and the tire (half) diameter direction. Furthermore, in the tire width direction, the tire center CL is used as the center, and the left and right sides are defined as the left and right sides toward the plane of the paper, with the side of the tire center CL being referred to as the inside and the opposite side as the outside.

[0010] As shown in each figure, the tire T comprises a bead core 12, carcass 14, belt layer 16, bead filler 20, rim cushion rubber 22, belt under rubber 24, side rubber 26, base rubber 28, tread rubber 30, inner liner 32, etc., which are mainly made of cord material. The bead core 12, carcass 14 and belt layer 16 form the skeleton of the tire T, while the inner liner 32, bead filler 20, rim cushion rubber 22, belt under rubber 24, side rubber 26, base rubber 28, and tread rubber 30 are provided as filler members to satisfy the performance requirements of each part of the tire T.

[0011] The bead core 12 is an assembly of steel cords formed in a ring shape, and is a pair of members provided separated in the width direction of the tire T. The steel cords forming the bead core 12 are formed in a ring shape by winding bead cords, which are formed by twisting or multi-twisting steel strands, a predetermined number of times. The contour shape of the bead core 12 in cross-section is formed in a polygonal shape such as a square or hexagon, or a circle, for example.

[0012] The carcass 14 is folded back from the inside to the outside of the bead cores 12 provided on the left and right sides, and is provided to extend in a toroidal shape between the left and right bead cores 12;12. The ends of the folded carcass 14 may terminate inside the tire radius beyond the maximum width of the tire T, outside the tire radius, or coincide with the maximum width. The carcass 14 is made up of, for example, one or more carcass plies stacked on top of each other. Each carcass ply is formed by arranging fiber cords or steel cords called ply cords in a curtain-like manner and bonding them to the carcass rubber, and is arranged so that the carcass cords extend in the tire radius direction in the tire T.

[0013] The belt layer 16 is wrapped around the tire circumferentially so as to overlap with the outer circumference of the crown portion of the carcass 14, at a position corresponding to the tread portion of the tire T. This suppresses the protrusion of the tread portion of the tire T due to rotation and provides a restraining effect while the vehicle is in motion.

[0014] The belt layer 16 is composed of, for example, one or more belt plies. As shown in Figure 3, the belt layer 16 in this embodiment is composed of three belt plies 17;18;19 stacked on top of each other. Each belt ply 17;18;19 is formed as a sheet-like member in which belt cords made of chemical fibers or steel are arranged in a curtain-like manner and covered with belt rubber to maintain that arrangement.

[0015] When the belt plies 17 and 18 are positioned on the outer circumference of the carcass 14, the belt cords 17A and 18A are formed to extend inclined with respect to the tire width direction. When the belt ply 19 is positioned on the outer circumference of the belt ply 18, the belt cord is formed to extend along the tire circumference. Hereinafter, the belt plies 17 and 18 will be referred to as inclined belts 17 and 18, and the belt ply 19 will be referred to as the circumferential belt 19.

[0016] The inclined belts 17 and 18 are provided in a stacked manner such that the belt cords 17A and 18A cross each other. For the belt cords 17A and 18A constituting the inclined belts 17 and 18, for example, those made of steel may be used, and for the belt cords constituting the circumferential belt 19, those made of materials other than steel may be used.

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

[0018] By setting the inclination angles of the belt cords 17A and 18A of the inclined belts 17 and 18 in this way, it is possible to reduce the input from the tread surface that causes noise while ensuring wear resistance and handling stability performance. Also, by setting a lower limit value for the inclination angles α17 and α18 of the belt cords 17A and 18A, it is possible to reduce the input from the tread surface that causes noise while ensuring wear resistance and handling stability performance.

[0019] [Rubber composition of the tire] The bead filler 20 is arranged to be filled in the space formed between the carcasses 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 side in the tire radius direction of the carcass 14. Thereby, the adhesion to the applicable rim when the tire T is mounted on the rim and the structure of the bead portion are protected.

[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, extends radially outward along the outer circumference of the carcass 14, and covers the side of the belt under rubber 24.

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

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

[0025] Multiple circumferential main grooves are formed in the tread rubber 30, extending in the circumferential direction of the tire. For example, as shown in Figure 1, one of the multiple circumferential main grooves, 31A, is formed so as to be located in the center of the tire width direction (including the tire center CL), or, although not shown, two or more circumferential main grooves are provided in the center region, for example, two or more on both sides of the tire center CL. The circumferential main groove 31A is, for example, a recess where a wear indicator indicating the wear limit of the tire T is set, and refers to the deepest recess formed in the tire T. The center region refers to a range of at least 25 to 75% of the tread width, with the center of the tread width at the 50% position. For example, in the case of a tire with a tread width of 160 mm, the range corresponding to 80 mm corresponds to the tire center CL as the symmetrical position. If the above range includes multiple main grooves, the range corresponding to only the center main groove located closest to the tire center CL corresponds to the range covering only the center main groove. Tread width refers to the distance in the tire width direction between the ends of the tread when the tire is mounted on the applicable rim, filled to the specified internal pressure, and under no load. Here, "applicable rim" refers to the industrial standard valid in the region where the tire is produced and used, and in Japan, it is the JATMA (Japan Automobile Tire Manufacturers Association) YEAR standard. BOOK, in Europe, is called ETRTO (European Tyre and Rim Technical Organisation) STANDARD MANUAL, known in the US as TRA (THE TIRE This refers to rims as defined in the RIM ASSOCIATION INC. YEAR BOOK, etc. Furthermore, "specified internal pressure" refers to the air pressure corresponding to the maximum load (maximum load capacity) of a single wheel in the applicable size as described 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, covering the entire inner circumference of the carcass 14. The inner liner 32 provides airtightness as a pneumatic tire.

[0027] [Changes in wall thickness (rubber thickness) from the inner surface of the carcass to the inner surface of the inner liner] Figures 4(a) to 4(c) show several examples of the formation of thickened regions according to this embodiment. In each figure, the members shown in gray indicate the members that form the thickened regions. As shown in Figure 4, in a cross-sectional view in the tire width direction, the tire T is formed such that the thickness t from the outer circumferential surface 14a of the carcass 14 to the inner circumferential surface 32a of the inner liner 32 is thicker than other parts in a predetermined range including at least the center in the tire width direction of the crown portion of the tire T. Hereinafter, this predetermined range will be referred to as the thickened region 40. Note that, considering that it is a molded rubber product, the thickness t in the thickened region 40 does not need to be uniform along the width direction.

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

[0029] When an interlayer rubber 34 is interposed to form a thickened region 40, there is an advantage in that a rubber material with different properties from the carcass rubber and inner liner 32 can be used. That is, by setting the tanδ of the interlayer rubber 34 to be larger or smaller than the tanδ of the carcass rubber and inner liner 32, it is possible to suppress vibrations by changing the mass distribution in the tire T while maintaining other properties required of the tire T. For example, by using a rubber with high hardness as the interlayer rubber 34, vibrations in the center of the tire in the width direction can be reduced, and noise performance can be improved.

[0030] Furthermore, in order to improve noise performance, if it is necessary to set the thickness of the thickened region 40 to be thicker, or to set the range in the tire width direction to be wider, or both, the thickened region 40 can be formed by changing the mass distribution in the tire T, thereby suppressing vibration and improving noise performance. This is achieved by changing the thickness of the carcass rubber that forms the carcass 14 or the rubber that forms the inner liner 32.

[0031] The width W40 of the thickened area 40 should be set to include at least the entire width of the circumferential main groove 31A formed in the center of the tire width direction of the tread portion. As mentioned above, when the belt layer 16 is configured in such a way that the thickness of the tread portion 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 tread portion is thin and vibrations are more easily amplified. Therefore, by forming a thickened region 40 that includes the tire center CL, vibrations caused by the structure can be suppressed. This is especially effective when the circumferential main groove 31A is formed on the tire center CL. Also, as mentioned 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, the width of the thickened region 40 may include all the circumferential main grooves formed in the center region, or it may be formed to correspond to each circumferential main groove.

[0032] Figure 5 shows another example of forming a thickened region. In order to improve noise performance, a wide width and thickness are required for the thickened region 40. For example, if a significant increase in the weight of the tire T is expected with the formation of the thickened region 40, it is preferable to form a thickened region 50 such that the width of the thickened region 40 on the inner liner 32 side is narrowed or the thickness is reduced, and in addition, 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 in the crown portion of the tire T is at least greater than the thickness in the area outside the predetermined range, including the center in the tire width direction.

[0033] Thus, in order to form a thickened region 50 in which 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 at least thicker than the thickness u in a predetermined range including the center in the tire width direction, the same method as for forming the thickened region 40 can be used. That is, as shown in Figure 5(a), a rubber member 38 formed in the shape of a sheet as a separate member may be interposed between the belt layer 16 and the base rubber 28, or as shown in Figure 5(b), the thickness may be directly changed by the rubber members that make up the base rubber 28.

[0034] In this way, by providing thickened regions 40;50 on both 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 belt layer 16 of the tire skeletal members in the tread portion is improved. As a result, the widths W40;W50 of the thickened regions 40;50 formed on the inner liner 32 side and the tread rubber 30 side, respectively, can be made narrower or thinner. Therefore, a more desirable contact shape can be achieved while suppressing an increase in the weight of the tire T. As a result, it is possible to improve noise performance while ensuring the wear resistance and handling performance of the tire T.

[0035] As explained above, by configuring the thickness of the tire T from the outer circumferential surface of the radial carcass to the inner circumferential surface of the inner liner in the crown portion of the tire, such that a portion is thicker than the thickness in a range outside of a predetermined range that includes at least the center in the tire width direction, it is possible to reduce the amplitude of noise in the frequency range that constitutes the structural vibration band while ensuring wear resistance and handling stability, thereby improving noise performance. Furthermore, compared to cases where thickness changes are made 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, especially in the high-frequency range that constitutes the slip band during tire rotation. In addition to the above configuration, by ensuring that the thickness from the outer surface of the belt layer to the outer surface of the tread rubber layer in the crown portion of the tire is at least greater than the thickness in a predetermined range including the center in the width direction of the tire, noise performance can be improved while ensuring wear resistance and handling stability by sandwiching the belt layer and carcass, which are the skeletal members of the tire. Furthermore, noise can be effectively reduced 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. Furthermore, by configuring the tire to include an inclined belt, which consists of multiple cords covered in rubber and extending at an angle with respect to the tire width direction, and a circumferential belt, which is positioned on the radially outer side of the inclined belt layer and extends in the circumferential direction of the tire, noise performance can be improved while maintaining tire 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 positioned between a pair of bead cores, An inner liner having a predetermined thickness is disposed on the radially inner side of the radial carcass, A belt layer positioned on the radially outer side of the radial carcass, A tread rubber layer is arranged on the outer side of the belt layer in the radial direction of the tire, A tire equipped with, The thickness from the outer circumferential surface of the radial carcass to the inner circumferential surface of the inner liner in the crown portion of the tire, And, The thickness from the outer circumferential surface of the belt layer to the outer circumferential surface of the tread rubber layer in the crown portion of the tire is: Each includes a portion that is thicker than the thickness in the area outside the predetermined range, which includes the center in the width direction of the tire. The tread rubber layer has a main groove on the tread surface at the center in the tire width direction within the predetermined range, The aforementioned thick portion is set to have a width that includes the entire main groove, but only with respect to the main groove formed on the center in the width direction of the tire. A tire characterized in that the thick portion of the crown portion of the tire, from the outer peripheral surface of the belt layer to the outer peripheral surface of the tread rubber layer, is formed by interposing a separate rubber member between the belt layer and the tread rubber layer.

2. The tire according to claim 1, characterized in that the thick portion within the predetermined range of thickness from the outer circumferential surface of the radial carcass to the inner circumferential surface of the inner liner in the crown portion of the tire is formed by interposing a separate rubber member between the radial carcass and the inner liner.

3. The tire according to claim 1, characterized in that the belt layer comprises an inclined belt made of a plurality of cords extending inclined with respect to the tire width direction and covered with rubber, and a circumferential belt arranged on the radial side of the inclined belt layer and made of a plurality of cords extending in the circumferential direction of the tire and covered with rubber.

Images