JP2020093703A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire capable of achieving weight saving while maintaining internal pressure holding performance and durability.SOLUTION: A pneumatic tire according to an embodiment comprises: a carcass ply 22 that leads to a bead core 18 of a bead part 16 through a side wall part 14 from a tread part 12, that is, the carcass ply 22 that includes a carcass cord arrangement body and topping rubber made of butyl rubber for coating both sides of the arrangement body; and an inner liner rubber layer 40 that is made of butyl rubber and provided from the side wall part 14 to the bead part 16 on the tire inner surface side of the carcass ply.SELECTED DRAWING: Figure 2

Description

Embodiments of the present invention relate to a pneumatic tire.

The pneumatic tire includes a carcass ply extending from the tread portion to the sidewall portion to the bead portion, and an inner liner rubber layer on the tire inner surface side of the carcass ply. The inner liner rubber layer is made of air-impermeable butyl rubber for holding the internal pressure, and is conventionally provided over the entire tire inner surface (lumen surface). Therefore, it is a factor of increasing the tire mass, and it is required to reduce the tire mass while maintaining the internal pressure holding performance.

In Patent Document 1, a topping rubber for a carcass ply is an inner topping rubber that forms a tire inner surface and is made of air-impermeable butyl-based rubber, and an outer surface of a sidewall portion that is made of non-butyl-based rubber. It is disclosed to be constituted with an outer topping rubber. Accordingly, Patent Document 1 discloses that the inner liner rubber layer and the sidewall rubber are omitted to reduce the tire mass while maintaining the internal pressure retention performance. However, in the configuration described in Patent Document 1, the interface between the inner topping rubber and the outer topping rubber existing at the position of the array of carcass cords is an interface between different types of rubber, so that the strain deformation of the tire causes the interface to disappear from the interface. Separation occurs, which becomes a factor of impairing durability.

JP, 2010-239958, A

An embodiment of the present invention has an object to provide a pneumatic tire capable of achieving weight reduction while maintaining internal pressure holding performance and durability.

Pneumatic tire according to an embodiment of the present invention is a carcass ply from the tread portion through the sidewall portion to the bead core of the bead portion, from a butyl rubber that covers both the carcass cord array and both surfaces of the array. A carcass ply including the topping rubber, and an inner liner rubber layer made of butyl rubber provided on the tire inner surface side of the carcass ply from the sidewall portion to the bead portion.

With the pneumatic tire according to the above embodiment, it is possible to reduce the weight while maintaining the internal pressure holding performance and the durability.

Half-sectional view of a pneumatic tire according to one embodiment Enlarged sectional view of the main part of FIG. III-III sectional view taken on the line of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The pneumatic tire 10 of the embodiment shown in FIG. 1 is a pneumatic tire for passenger cars, and includes a tread portion 12 that constitutes a ground contact surface, a pair of left and right bead portions 16 fixed to a rim, a tread portion 12 and a bead. It is provided with a pair of left and right side wall portions 14 interposed between the side wall portion 14 and the portion 16. Note that FIG. 1 is a right half cross-sectional view of the tire 10 cut along a meridional section including the tire rotation axis, and in this example, the tire 10 is bilaterally symmetric.

In the figure, reference sign CL indicates a tire equatorial plane corresponding to the center of the tire axial direction. In the present specification, the tire axial direction means a direction parallel to the tire rotation axis, and is indicated by reference numeral WD in FIG. The inner side in the tire axial direction WD is a direction closer to the tire equatorial plane CL, and the outer side in the tire axial direction WD is a direction away from the tire equatorial plane CL. The tire radial direction means a direction perpendicular to the tire rotation axis, and is indicated by reference numeral RD in FIG. The inside of the tire radial direction RD is a direction approaching the tire rotation axis, and the outside of the tire radial direction RD is a direction moving away from the tire rotation axis. The tire circumferential direction refers to the direction of rotation around the tire rotation axis.

In the bead portion 16, an annular bead core 18 made of a bead wire and a bead filler 20 made of hard rubber and having a substantially triangular cross-section with a narrower width toward the tip end installed on the outer periphery of the bead core 18 are embedded. ..

The tire 10 is provided with a carcass ply 22 that is bridged in a toroidal shape between the pair of bead portions 16. The carcass ply 22 extends from the tread portion 12 through the sidewall portion 14 to the bead core 18 of the bead portion 16 and is locked at the bead portion 16. More specifically, the carcass ply 22 has both ends folded around the bead core 18 from the inner side to the outer side in the tire axial direction WD and locked. Therefore, the carcass ply 22 includes a toroidal ply body portion 22A extending between the pair of bead cores 18 and a ply folded portion 22B that is folded around the bead core 18 from both ends of the ply body portion 22A. The bead core 18 and the bead filler 20 are arranged between the ply body 22A and the ply folded portion 22B.

The carcass ply 22 is configured to include an array body 24 of carcass cords 24A as a reinforcing material and a topping rubber 26 that covers the array body 24 (see FIG. 3). The array body 24 is formed by arranging carcass cords 24A in parallel with a predetermined number of driving, and the carcass cords 24A are arranged substantially at right angles (for example, 80° to 90°) to the tire circumferential direction, that is, along the meridian direction. Has been done. Examples of the carcass cord 24A include polyester fiber, rayon fiber, aramid fiber, organic fiber cord such as nylon fiber, or steel cord.

In the tread portion 12, a belt layer 28 is provided on the outer periphery of the carcass ply 22 (that is, on the outer side in the tire radial direction RD), and a tread rubber 30 forming a grounding surface is laminated on the outer periphery of the belt 28 layer. The belt layer 28 is provided so as to overlap the outer circumference of the crown portion of the carcass ply 22 and is usually composed of at least two belt plies. In this example, the belt layer 28 is composed of two sheets, a first belt 28A serving as a maximum width belt and a second belt 28B arranged so as to overlap the outer circumference thereof. The first and second belts 28A and 28B are formed by inclining belt cords such as steel cords at a constant angle (for example, 10° to 35°) with respect to the tire circumferential direction and arranged at predetermined intervals in the tire axial direction WD. Become. The belt cords are arranged so as to intersect each other between the two belts 28A and 28B.

A belt reinforcing layer 32 is provided on the outer side of the belt layer 28 in the tire radial direction RD, that is, between the belt layer 28 and the tread rubber 30. The belt reinforcing layer 32 is composed of a cap ply having a cord extending substantially parallel to the tire circumferential direction.

On the tire outer surface side of the carcass ply 22 in the sidewall portion 14, a sidewall rubber 34 forming the tire outer surface is provided. In this example, the sidewall rubber 34 has an outer end 34A in the tire radial direction RD that covers the outer end 30A of the tread rubber 30 in the tire axial direction WD.

A rim strip rubber 36 is provided on the bead portion 16. The rim strip rubber 36 is a rubber member that forms an outer surface of the bead portion 16 and contacts the rim. The rim strip rubber 36 is provided in the bead portion 16 so as to cover the ply body portion 22A and the ply folded portion 22B of the carcass ply 22 from the inside in the tire radial direction RD.

As shown in FIG. 2, the rim strip rubber 36 includes an outer winding portion 36A that is wound outside the bead core 18 in the tire axial direction WD along the outer surface of the ply folded portion 22B, and the bead core 18 along the ply body portion 22A. And an inner winding portion 36B wound inside the tire axial direction WD. The outer end portion 36AE of the outer winding portion 36A in the tire radial direction RD is covered by the inner end portion 34B of the sidewall rubber 34 in the tire radial direction RD, and the joint portion between the side wall rubber 34 and the rim strip rubber 36. Is formed to project as a rim protector 38.

In this embodiment, an air impermeable butyl rubber is used as the topping rubber 26 that covers both the front and back surfaces of the array 24 of the carcass ply 22 (see FIG. 3 ). Specifically, the topping rubber 26 is composed of an inner topping rubber 26A that covers the tire inner surface side of the array 24 and an outer topping rubber 26B that covers the tire outer surface side of the array 24. The inner topping rubber 26A and the outer side Both topping rubbers 26B are made of butyl rubber. The inner topping rubber 26A and the outer topping rubber 26B may have the same composition or different compositions as long as they are butyl rubber.

In the present specification, the butyl rubber is a rubber containing butyl rubber (IIR) and/or its derivative in an amount of 60% by mass or more in 100% by mass of a rubber polymer. Examples of the butyl rubber derivative include halogenated butyl rubber such as chlorinated butyl rubber obtained by reacting butyl rubber with chlorine, bromine and the like, and brominated butyl rubber. The butyl rubber may contain, as the balance of the rubber polymer, one or more diene rubbers such as natural rubber (NR), butadiene rubber (BR) or styrene butadiene rubber (SBR). Further, butyl rubber, as well as general topping rubber, if necessary, various additives, such as reinforcing agents such as carbon black, crosslinking agents such as sulfur, zinc white, vulcanization accelerator, stearic acid, etc. You may add the softening agent of this.

The thickness T1 of the carcass ply 22 (the total thickness including the front and back topping rubbers 26A and 26B; see FIG. 3) is not particularly limited, but is preferably 0.8 to 1.3 mm, and is as much as possible from the viewpoint of weight reduction. It is preferably formed thin.

An inner liner rubber layer 40 made of air impermeable butyl-based rubber is provided on the tire inner surface side of the carcass ply 22. As shown in FIG. 1, the inner liner rubber layer 40 forms a tire cavity surface from the sidewall portion 14 to the bead portion 16, and is provided so as to overlap with the tire inner surface side of the ply body portion 22A of the carcass ply 22. ing. As the butyl rubber of the inner liner rubber layer 40, the same butyl rubber as the topping rubber 26 can be used, and may have the same composition as the topping rubber 26 or a different composition.

The inner liner rubber layer 40 has a hollow structure omitted in the tread portion 12, extends from the bead portion 16 to the sidewall portion 14, and is a boundary portion between the sidewall portion 14 and the tread portion 12. The shoulder portion 13 terminates.

In this example, as shown in FIG. 2, the inner liner rubber layer 40 extends to the outside of the tire radial direction RD from the side of the bead portion 16, more specifically, the bead core 18, which is the lower end portion of the bead portion 16, and It ends at a position where it overlaps with the end portion 28E of the belt layer 28 via the ply 22.

That is, it is preferable that the lower end (end inside the tire radial direction RD) 40AE of the inner liner rubber layer 40 be located inside the outer peripheral surface 18A of the bead core 18 in the tire radial direction RD. In this case, the inner end portion 40A of the inner liner rubber layer 40 in the tire radial direction RD has a portion overlapping the bead core 18 in the tire radial direction RD. The lower end 40AE of the inner liner rubber layer 40 may be within the range of the cross-sectional height of the bead core 18 in the tire radial direction RD.

Further, the upper end (end outside the tire radial direction RD) 40BE of the inner liner rubber layer 40 is located inside the end 28AE of the belt layer 28 in the tire axial direction WD and in the tire axial direction WD, and Ends within a range corresponding to the end portion 28E of the. Therefore, the outer end 40B of the inner liner rubber layer 40 in the tire radial direction RD overlaps the end 28E of the belt layer 28.

Here, the end 28AE of the belt layer 28 is an end in the tire axial direction of the first belt 28A that is the maximum width belt. The end portion 28E of the belt layer 28 is a range from the end 28AE to 15% of the total width W0 (see FIG. 1) of the belt layer 28 in the tire axial direction WD, and more preferably 10% of the total width W0 from the end 28AE. The range is up to.

The inner end portion 40A of the inner liner rubber layer 40 in the tire radial direction RD is provided so as to overlap with the inner surface of the inner winding portion 36B of the rim strip rubber 36 on the tire inner surface side. Therefore, in the bead portion 16, the inner winding portion 36B is laminated on the tire inner surface side of the ply body portion 22A, and the inner end portion 40A of the inner liner rubber layer 40 is laminated on the tire inner surface side.

In the pneumatic tire 10 according to the present embodiment, the carcass ply 22 can have a function as an inner liner for maintaining the tire internal pressure by using the butyl rubber for the topping rubber 26 of the carcass ply 22. it can. Therefore, the inner liner rubber layer 40 can be omitted in the tread portion 12 where air is difficult to penetrate due to the large thickness and the large number of members. That is, since the inner liner rubber layer 40 can be provided from the side wall portion 14 to the bead portion 16 and can be omitted in most of the tread portion 12, the rubber amount of the inner liner rubber layer 40 can be reduced while maintaining the internal pressure holding performance. It is possible to reduce the weight and reduce the weight of the tire.

In addition, the carcass ply 22 has an inner topping rubber 26A and an outer topping rubber 26B that cover the front and back sides thereof, both of which are made of butyl-based rubber, and are made of the same kind of rubber. Therefore, the adhesion between the inner topping rubber 26A and the outer topping rubber 26B is improved. Excellent and can suppress the separation.

As described above, with the pneumatic tire 10 according to the present embodiment, it is possible to reduce rolling resistance due to weight reduction while maintaining the internal pressure retention performance and durability.

In addition, according to the present embodiment, the strain deformation of the tire 10 is suppressed by terminating the outer end portion 40B of the inner liner rubber layer 40 in the tire radial direction RD so as to overlap with the end portion 28E of the belt layer 28. The durability can be improved.

Further, since the inner end portion 40A of the inner liner rubber layer 40 in the tire radial direction RD is provided so as to overlap with the tire inner surface side of the inner winding portion 36B of the rim strip rubber 36, the joint surface of the two in the tire radial direction RD is formed. Secured for a long time. Therefore, the separation at the interface between the both can be suppressed, and the air permeation resistance of the bead portion 16 can be improved.

Further, in this embodiment, the inner liner rubber layer 40 provided on the side portion of the tire 10, that is, from the sidewall portion 14 to the bead portion 16 is made thin by providing the carcass ply 22 with an internal pressure holding function. You can For example, the maximum thickness T2 (see FIG. 3) of the inner liner rubber layer 40 can be set to 0.5 to 1.0 mm. By thus thinning the inner liner rubber layer 40 at the side portions, the amount of rubber can be further reduced, and the weight of the tire can be reduced.

In addition, in the said embodiment, although the case where the number of carcass plies was one was demonstrated, you may provide two or more carcass plies. That is, the present invention can be applied to a pneumatic tire including at least one carcass ply. When the carcass ply has a plurality of carcass plies, it is preferable that the carcass ply located on the innermost side of the tire is formed of butyl rubber as the topping rubber on both the front and back surfaces thereof. That is, in one embodiment, the pneumatic tire includes at least one carcass ply, and the carcass ply located on the innermost side of the tire among the at least one carcass ply is the carcass cord array and the array. It is preferable to include a topping rubber made of butyl rubber that covers both surfaces of the. In that case, for the other carcass plies, the topping rubber may be formed of butyl rubber, but it is preferable to form the normal non-butyl rubber other than butyl rubber.

In the above-described embodiment, not only the ply body portion 22A of the carcass ply 22 but also the whole of the ply folded portion 22B, the topping rubbers 26A and 26B on the front and back sides thereof are formed of butyl rubber, but the ply folded portion 22B is It is not always necessary to form the butyl rubber, and for example, the ply folded portion 22B may be formed of the non-butyl rubber.

The dimensions and the like of each part of the pneumatic tire are values measured with the pneumatic tire mounted on the regular rim and filled with the regular internal pressure. The regular rim is a rim that is defined for each tire in the standard system including the standard on which the tire is based. For example, JATMA is a standard rim, TRA is "Design Rim", and ETRTO is " Measuring Rim". The regular internal pressure is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. For JATMA, the maximum air pressure is used, and for TRA, the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION" is used. The maximum value described in "PRESSURES" is "INFLATION PRESSURE" for ETRTO.

Although some embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. The embodiments and their modifications are included in the scope of the invention and the scope thereof, and are included in the invention described in the claims and the scope of equivalents thereof.

10... Pneumatic tire, 12... Tread part, 14... Side wall part, 16... Bead part, 18... Bead core, 22... Carcass ply, 24... Array, 24A... Carcass cord, 26... Topping rubber, 26A... Inner topping Rubber, 26B... Outer topping rubber, 28 Belt layer, 28E... End of belt layer, 36... Rim strip rubber, 36B... Inner winding portion, 40... Inner liner rubber layer, 40A... Inner liner rubber layer inner side in tire radial direction End part, 40B... Tire radial direction outer end part of inner liner rubber layer, WD... Tire axial direction, RD... Tire radial direction

Claims (4)

A carcass ply from the tread portion through the sidewall portion to the bead core of the bead portion, a carcass ply including an array of carcass cords and a topping rubber made of butyl rubber that covers both surfaces of the array,
An inner liner rubber layer made of butyl rubber provided from the sidewall portion to the bead portion on the tire inner surface side of the carcass ply,
Pneumatic tire equipped with. The pneumatic tire according to claim 1, wherein the inner liner rubber layer extends outward from the bead portion in the tire radial direction and ends at a position where the inner liner rubber layer overlaps the end portion of the belt layer via the carcass ply. The rim strip rubber provided in the bead portion includes an inner winding portion that is wound inside the bead core in the tire axial direction, and a tire radial inner end of the inner liner rubber layer is a tire inner surface side of the inner winding portion. The pneumatic tire according to claim 1, which is provided so as to be overlapped with the pneumatic tire. The pneumatic tire according to any one of claims 1 to 3, wherein the maximum thickness of the inner liner rubber layer is 0.5 to 1.0 mm.

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