JP7154989B2 - pneumatic tire - Google Patents

Description

Embodiments of the present invention relate to pneumatic tires.

A pneumatic tire includes a carcass ply extending from a tread portion to a sidewall portion to a 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 to retain internal pressure, and is conventionally provided over the entire tire inner surface (bore surface). As a result, the tire mass increases, and it is required to reduce the tire mass while maintaining the internal pressure retention performance.

In Patent Document 1, the topping rubber of the carcass ply is composed of an inner topping rubber that forms the inner cavity surface of the tire and is made of air-impermeable butyl rubber, and an outer surface of the sidewall portion that is made of non-butyl rubber. It is disclosed to be constructed 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 carcass cord array is an interface between rubbers of different types. Separation occurs, which is a factor that impairs durability.

JP 2010-239958 A

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

A pneumatic tire according to an embodiment of the present invention is a carcass ply extending from a tread portion to a bead core of a bead portion via a sidewall portion, and is composed of a carcass cord arrangement and a butyl-based rubber covering both surfaces of the arrangement. and an inner liner rubber layer made of butyl-based rubber provided from the sidewall portion to the bead portion on the tire inner surface side of the carcass ply.

With the pneumatic tire according to the above embodiment, weight reduction can be achieved while maintaining internal pressure retention performance and durability.

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

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

A pneumatic tire 10 of the embodiment shown in FIG. 1 is a pneumatic tire for a passenger car, and includes a tread portion 12 forming a contact surface, a pair of left and right bead portions 16 fixed to the rim, and the tread portion 12 and the bead. A pair of left and right side wall portions 14 are interposed between the side wall portion 16 and the side wall portion 16 . Note that FIG. 1 is a right half 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 symmetrical.

In the figure, the symbol CL indicates the tire equatorial plane corresponding to the axial center of the tire. As used herein, the tire axial direction refers to a direction parallel to the tire rotation axis, and is indicated by symbol WD in FIG. The inner side in the tire axial direction WD is the direction toward the tire equatorial plane CL, and the outer side in the tire axial direction WD is the direction away from the tire equatorial plane CL. A tire radial direction means a direction perpendicular to the tire rotation axis, and is indicated by symbol RD in FIG. The inner side in the tire radial direction RD is the direction toward the tire rotation axis, and the outer side in the tire radial direction RD is the direction away from the tire rotation axis. The tire circumferential direction is the direction in which the tire rotates 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-sectional shape, which is set on the outer periphery of the bead core 18 and narrows toward the tip, are embedded. .

The tire 10 is provided with a carcass ply 22 that is toroidally bridged 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 . Specifically, both ends of the carcass ply 22 are folded back 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 main body portion 22A that straddles the pair of bead cores 18 and ply turn-up portions 22B that are turned around the bead cores 18 from both ends of the ply main body portion 22A. A bead core 18 and a bead filler 20 are arranged between the ply body portion 22A and the ply turn-up portion 22B.

The carcass ply 22 includes an arrangement 24 of carcass cords 24A as a reinforcing material and a topping rubber 26 covering the arrangement 24 (see FIG. 3). The array body 24 is formed by arranging a predetermined number of carcass cords 24A in parallel, and the carcass cords 24A are arranged substantially perpendicular to the tire circumferential direction (for example, 80° to 90°), that is, along the meridian direction. It is Examples of the carcass cords 24A include organic fiber cords such as polyester fibers, rayon fibers, aramid fibers, nylon fibers, and steel cords.

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 contact surface is laminated on the outer periphery of the belt 28 layer. The belt layer 28 is superimposed on the outer circumference of the crown portion of the carcass ply 22, and is normally composed of at least two belt plies. In this example, the belt layer 28 is composed of two belts, a first belt 28A as a maximum width belt and a second belt 28B superimposed on the outer periphery thereof. The first and second belts 28A, 28B are belt cords such as steel cords that are inclined 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. Belt cords are arranged to cross each other between the two belts 28A and 28B.

A belt reinforcing layer 32 is provided outside 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 cords extending substantially parallel to the tire circumferential direction.

A sidewall rubber 34 constituting the tire outer surface is provided on the tire outer surface side of the carcass ply 22 in the sidewall portion 14 . 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 the outer surface of the bead portion 16 and contacts the rim. The rim strip rubber 36 is provided so as to cover the ply body portion 22A and the ply turn-up portion 22B of the carcass ply 22 at the bead portion 16 from the inside in the tire radial direction RD.

As shown in FIG. 2 , the rim strip rubber 36 includes an outer rolled-up portion 36A rolled up along the outer surface of the ply turn-up portion 22B to the outside of the bead core 18 in the axial direction WD of the tire, and an outer rolled-up portion 36A rolled up along the outer surface of the ply turn-up portion 22B, and a bead core 18 along the ply body portion 22A. and an inner roll-up portion 36B rolled up on the inner side in the tire axial direction WD. An outer end portion 36AE of the outer roll-up portion 36A in the tire radial direction RD is covered with an inner end portion 34B of the sidewall rubber 34 in the tire radial direction RD. is formed as a rim protector 38.

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

As used herein, butyl rubber is rubber containing 60% by mass or more of butyl rubber (IIR) and/or derivatives thereof in 100% by mass of rubber polymer. Derivatives of butyl rubber include halogenated butyl rubber such as chlorinated butyl rubber and brominated butyl rubber obtained by reacting butyl rubber with chlorine, bromine, or the like. The butyl-based rubber may contain, as the remainder of the rubber polymer, one or more diene-based rubbers such as natural rubber (NR), butadiene rubber (BR), or styrene-butadiene rubber (SBR). As with general topping rubbers, butyl rubber may contain various additives, such as reinforcing agents such as carbon black, cross-linking agents such as sulfur, zinc white, vulcanization accelerators, stearic acid, etc., if necessary. A softening agent or the like may be added.

The thickness T1 of the carcass ply 22 (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 preferable to form it thinly.

An inner liner rubber layer 40 made of air impermeable butyl 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 the inner cavity surface of the tire from the sidewall portion 14 to the bead portion 16, and is provided overlapping the tire inner surface side of the ply body portion 22A of the carcass ply 22. ing. As the butyl-based rubber of the inner liner rubber layer 40, the same rubber as the topping rubber 26 can be used, and the same compound as the topping rubber 26 or a different compound can be used.

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. It terminates at a shoulder portion 13 .

In this example, as shown in FIG. 2, the inner liner rubber layer 40 extends outward in 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 the carcass. It terminates at a position overlapping the end portion 28E of the belt layer 28 via the ply 22 .

That is, it is preferable that the lower end (the inner end in the tire radial direction RD) 40AE of the inner liner rubber layer 40 is 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 that overlaps 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.

In addition, the upper end 40BE of the inner liner rubber layer 40 (outer end in the tire radial direction RD) is positioned inside in the tire axial direction WD of the end 28AE of the belt layer 28 in the tire axial direction WD. is terminated within a range corresponding to the end 28E of. Therefore, the outer end portion 40B of the inner liner rubber layer 40 in the tire radial direction RD overlaps with the end portion 28E of the belt layer 28 .

Here, the end 28AE of the belt layer 28 is the axial end of the first belt 28A, which 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, more preferably 10% of the total width W0 from the end 28AE. The range is up to

An inner end portion 40A of the inner liner rubber layer 40 in the tire radial direction RD is provided overlapping the tire inner surface side of the inner rolled-up portion 36B of the rim strip rubber 36 . Therefore, in the bead portion 16, the inner roll-up 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 use of butyl-based rubber for the topping rubber 26 of the carcass ply 22 allows the carcass ply 22 to function as an inner liner for maintaining the internal pressure of the tire. can. Therefore, the inner liner rubber layer 40 can be omitted in the tread portion 12, which has a large thickness and a large number of members, so that it is difficult for air to pass therethrough. That is, since the inner liner rubber layer 40 is provided from the sidewall portion 14 to the bead portion 16 and can be omitted from most of the tread portion 12, the amount of rubber of the inner liner rubber layer 40 can be reduced while maintaining the internal pressure retention performance. It can be reduced to make the tire lighter.

In the carcass ply 22, the inner topping rubber 26A and the outer topping rubber 26B that cover the front and back sides are both made of butyl rubber, and are made of the same type of rubber. It is excellent and can suppress separation.

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

Further, according to the present embodiment, 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 while overlapping the end portion 28E of the belt layer 28. durability can be improved.

In addition, since the inner end portion 40A of the inner liner rubber layer 40 in the tire radial direction RD is overlapped with the tire inner surface side of the inner rolled-up portion 36B of the rim strip rubber 36, the joint surface of the two in the tire radial direction RD is aligned. secured for a long time. Therefore, separation at the interface between the two can be suppressed, and air permeation resistance at the bead portion 16 can be improved.

In addition, in the present embodiment, the inner liner rubber layer 40 provided from the side wall portion 14 to the bead portion 16 of the tire 10, that is, from the sidewall portion 14 to the bead portion 16, can be made thinner by giving the carcass ply 22 an internal pressure retaining function. can be done. For example, the maximum thickness T2 (see FIG. 3) of the inner liner rubber layer 40 can be set to 0.5-1.0 mm. By thinning the inner liner rubber layer 40 at the side portions in this manner, the amount of rubber can be further reduced, and the weight of the tire can be reduced.

In addition, although the case where the number of carcass plies is one has been described in the above embodiment, a plurality of carcass plies may be provided. That is, the present invention can be applied to pneumatic tires with at least one carcass ply. When the tire has a plurality of carcass plies, it is preferable that the topping rubbers on both the front and back surfaces of the carcass ply located on the innermost side of the tire are made of butyl-based rubber as described above. That is, in one embodiment, the pneumatic tire includes at least one carcass ply, and the carcass ply located closest to the inner surface of the tire among the at least one carcass ply is an array of carcass cords and the array of carcass cords. It is preferable to include a topping rubber made of butyl-based rubber covering both surfaces of the . In that case, the other carcass plies may be made of a butyl-based rubber as the topping rubber, but are preferably made of a normal non-butyl-based rubber other than the butyl-based rubber.

In the above embodiment, not only the ply body portion 22A of the carcass ply 22 but also the ply turn-up portion 22B as a whole includes the front and back topping rubbers 26A and 26B made of butyl rubber. The ply turn-up portion 22B need not necessarily be made of butyl-based rubber, and may be made of non-butyl-based rubber, for example.

The dimensions and the like of each part of the pneumatic tire are values measured with the pneumatic tire mounted on a regular rim and filled with regular internal pressure. A regular rim is a rim defined for each tire in a standard system that includes the standard on which the tire is based. Measuring Rim". The regular internal pressure is the air pressure determined for each tire by each standard in the standard system including the standard that the tire is based on. PRESSURES", or "INFLATION PRESSURE" for ETRTO.

Although several embodiments of the invention have been described above, these embodiments are presented by way of example 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 modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

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

Claims (3)

a carcass ply extending from the tread portion to the bead core of the bead portion through the sidewall portion, the carcass ply including a carcass cord array and a topping rubber made of butyl rubber covering both surfaces of the array;
an inner liner rubber layer made of butyl-based rubber provided from the sidewall portion to the bead portion on the tire inner surface side of the carcass ply;
with
The pneumatic tire, wherein the inner liner rubber layer extends outward in the tire radial direction from the bead portion and terminates at a position overlapping an end portion of the belt layer via the carcass ply . a carcass ply extending from the tread portion to the bead core of the bead portion through the sidewall portion, the carcass ply including a carcass cord array and a topping rubber made of butyl rubber covering both surfaces of the array;
an inner liner rubber layer made of butyl-based rubber provided from the sidewall portion to the bead portion on the tire inner surface side of the carcass ply;
with
A pneumatic tire , wherein the inner liner rubber layer has a maximum thickness of 0.5 to 1.0 mm. The rim strip rubber provided on the bead portion has an inner rolled-up portion rolled up axially inward of the bead core, and the inner liner rubber layer has an inner end portion in the tire radial direction on the inner surface side of the inner rolled-up portion. 3. The pneumatic tire according to claim 1 or 2, provided in an overlapping manner.

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