WO2020090851A1

WO2020090851A1 - Tire

Info

Publication number: WO2020090851A1
Application number: PCT/JP2019/042469
Authority: WO
Inventors: 崇之藏田; 正之有馬
Original assignee: 株式会社ブリヂストン
Priority date: 2018-10-31
Filing date: 2019-10-30
Publication date: 2020-05-07
Also published as: JP7099932B2; JP2020069897A

Abstract

According to the present invention, a bead part (60) has: an annular bead core (61) formed of resin-coated cords (61a) and extending in the tire circumferential direction; and a bead filler (62) arranged adjacent to the outside of the bead core (61) in the tire radial direction and composed of a resin material. A carcass (40) has: a main body section (41); and a folded-back section (42) connected to the main body section (41) and folded back outward in the tire width direction via the bead cores (61). An end portion (42a) of the folded back section (42) is positioned further inward in the tire radial direction than an end portion (62a) on the outside of the bead filler (62) in the tire radial direction.

Description

tire

The present invention relates to a tire.

Generally, a carcass, which is a member that forms a skeleton of a tire, is connected to the main body and a main body that extends in a toroidal shape across a pair of bead cores, and is folded back to the outside in the tire width direction through the bead core. It has a folded portion (Patent Document 1).

The carcass body and the folded portion described in Patent Document 1 are formed so as to sandwich the bead core and the bead filler. That is, the end portion of the folded portion described in Patent Document 1 is formed on the tire radial direction outer side than the tire radial direction outer end portion of the bead filler.

Japanese Unexamined Patent Publication No. 9-300921

In recent years, as the demand for environmental protection has increased, the weight reduction of tires is also required. As a measure for reducing the weight of the tire, it is conceivable to reduce the height of the folded portion in the invention described in Patent Document 1.

However, if the height of the folded-back portion is reduced, the input from the rim wheel concentrates on the end of the folded-back portion, and a large strain occurs at the end of the folded-back portion. As a result, there is a risk that the end of the folded-back portion will break down.

Therefore, the present invention has been made in view of such a situation, and an object thereof is to provide a tire capable of preventing a failure of an end portion of a folded-back portion even when the height of the folded-back portion is reduced. To do.

A tire (tire 10) according to one aspect of the present invention includes a tread portion (tread portion 20) that is in contact with a road surface, and a tire side portion (tire side portion 30) that is continuous with the tread portion and that is located inside the tread portion in the tire radial direction. And a carcass (carcass 40) that forms a skeleton of the tire and a bead portion (bead portion 60) that is continuous with the tire side portion and that is located inside the tire side portion in the tire radial direction. The bead portion is formed of a resin-coated cord (cord 61a), and has an annular bead core (bead core 61) extending in the tire circumferential direction, and a bead made of a resin material, which is arranged adjacent to the outside of the bead core in the tire radial direction. And a filler (bead filler 62). The carcass has a main body portion (main body portion 41) and a folded portion (folded portion 42) that is continuous with the main body portion and is folded back to the outside in the tire width direction via the bead core. The end portion (end portion 42a) of the folded-back portion is located on the tire radial direction inner side with respect to the tire radial direction outer end portion (end portion 62a) of the bead filler.

According to the tire described above, even if the height of the folded-back portion is reduced, it is possible to prevent the failure of the end portion of the folded-back portion.

FIG. 1 is a cross-sectional view of a tire along a tire width direction and a tire radial direction. FIG. 2 is an enlarged cross-sectional view of the bead portion. FIG. 3 is an enlarged cross-sectional view of the bead portion. FIG. 4 is an enlarged cross-sectional view of the bead portion. FIG. 5 is an enlarged cross-sectional view of the bead portion.

Embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings, the same parts are designated by the same reference numerals and the description thereof will be omitted.

(1) Overall Schematic Configuration of Tire FIG. 1 is a cross-sectional view of a tire 10 taken along a tire width direction and a tire radial direction. In FIG. 1, cross-sectional hatching is omitted (the same applies below).

As shown in FIG. 1, the tire 10 includes a tread portion 20, a tire side portion 30, a carcass 40, a belt layer 50, and a bead portion 60.

The tread portion 20 is a portion in contact with the road surface (not shown). The tread portion 20 is formed with a pattern (not shown) according to the usage environment of the tire 10 and the type of vehicle to which the tire 10 is attached.

The tire side portion 30 is connected to the tread portion 20 and is located inside the tread portion 20 in the tire radial direction. The tire side portion 30 is an area from the tire width direction outer end of the tread portion 20 to the upper end of the bead portion 60. The tire side portion 30 is sometimes called a sidewall or the like.

The carcass 40 forms the skeleton of the tire 10. The carcass 40 is a radial structure having carcass cords (not shown) radially arranged along the tire radial direction. However, the carcass 40 is not limited to the radial structure, and may have a bias structure in which the carcass cords are arranged so as to intersect in the tire radial direction.

The belt layer 50 is provided on the tire radial inside of the tread portion 20. The belt layer 50 is a resin-coated single-layer spiral belt as shown in FIG. A resin material described below is used as the resin material forming the belt layer 50. However, the belt layer 50 is not limited to the single-layer spiral belt. For example, the belt layer 50 may be a rubber-coated two-layer cross belt.

The bead portion 60 is continuous with the tire side portion 30 and is located inside the tire side portion 30 in the tire radial direction. The bead portion 60 has an annular shape, and the carcass 40 is folded back from the tire width direction inner side to the tire width direction outer side via the bead portion 60.

(2) Configuration of the bead portion 60 Next, a specific configuration of the bead portion 60 will be described. FIG. 2 is an enlarged cross-sectional view of the bead portion 60. Specifically, FIG. 2 is a cross-sectional view of the bead portion 60 along the tire width direction and the tire radial direction.

As shown in FIG. 2, the carcass 40 is folded back to the outside in the tire width direction via the bead portion 60. Specifically, the carcass 40 includes a body portion 41 and a folded portion 42.

The body portion 41 is a portion that is provided over the tread portion 20, the tire side portion 30, and the bead portion 60 and is folded back at the bead portion 60.

The folded-back portion 42 is a portion that is continuous with the main body portion 41 and is folded back to the outside in the tire width direction via the bead core 61.

The bead portion 60 is formed of a resin-coated cord 61a, and has an annular bead core 61 extending in the tire circumferential direction, and a bead filler 62 disposed adjacent to the bead core 61 on the tire radial outer side.

As shown in FIG. 2, the bead core 61 is formed by stacking a plurality of (for example, three) resin-coated cords 61a in the tire circumferential direction (for example, three layers). The cord 61a is made of metal such as steel.

A resin material having a higher tensile elastic modulus than the rubber material forming the tire side portion 30 and the rubber material forming the tread portion 20 is used as the resin coating the cord 61a. As the resin coating the cord 61a, a thermoplastic resin having elasticity, a thermoplastic elastomer (TPE), a thermosetting resin, or the like can be used. Considering elasticity during running and moldability during manufacturing, it is desirable to use a thermoplastic elastomer.

As the thermoplastic elastomer, a polyolefin thermoplastic elastomer (TPO), a polystyrene thermoplastic elastomer (TPS), a polyamide thermoplastic elastomer (TPA), a polyurethane thermoplastic elastomer (TPU), a polyester thermoplastic elastomer (TPC). , Dynamically crosslinkable thermoplastic elastomer (TPV) and the like.

Further, examples of the thermoplastic resin include polyurethane resin, polyolefin resin, vinyl chloride resin, and polyamide resin. Further, as the thermoplastic resin material, for example, the deflection temperature under load (0.45 MPa load) specified by ISO75-2 or ASTM D648 is 78 ° C or more, and the tensile yield strength specified by JIS K7113 is 10 MPa. As described above, it is also possible to use one having a tensile elongation at break (JIS K7113) of 50% or higher and a Vicat softening temperature (A method) of 130 ° C or higher defined by JIS K7206.

The bead filler 62 has a triangular shape whose thickness gradually decreases toward the outside in the tire radial direction. The bead filler 62 is also made of the above-mentioned resin material, like the bead core 61.

The end portion 42a of the folded-back portion 42 is located on the tire radial direction inner side of the tire radial direction outer end portion 62a of the bead filler 62. That is, as shown in FIG. 2, a part of the bead filler 62 is sandwiched between the main body portion 41 of the carcass 40 and the folded portion 42. However, the entire bead filler 62 is not sandwiched between the main body portion 41 and the folded portion 42. In other words, the end portion 42a of the folded-back portion 42 is adjacent to the tire width direction outer side surface of the bead filler 62.

(3) Action / Effect Next, the action and effect of the tire 10 will be described.
In the present embodiment, the end portion 42a of the folded-back portion 42 is located on the tire radial direction inner side of the tire radial direction outer end portion 62a of the bead filler 62. That is, the height of the folded-back portion 42 (tire cross-section height) in this embodiment is lower than that in the conventional technique. As a result, the material forming the carcass 40 is reduced, so that the weight of the tire 10 is reduced. Further, in this embodiment, the bead core 61 is made of a resin material, and the bead filler 62 adjacent to the bead core 61 is also made of a resin material. Since the elastic modulus of the resin material is higher than that of the rubber material as described above, the rotation of the bead core 61 is suppressed. This point will be described below in comparison with the related art.

The outside of the bead turns in the tire width direction when the bead collapses when the side is deformed due to the tire ground contact load, or when the lateral force that acts toward the inside of the turn acts on the tire from the road surface when the vehicle turns. When the sidewall part slides inward on the rim wheel and the sidewall part largely falls inward by turning due to the moment based on the lateral force, a force in the rotating direction of the bead core is generated. As in the prior art, when the bead core (excluding the code part) is made of rubber material, the rotational rigidity of the bead core is lower than when the bead core (excluding the code part) is made of resin material. The bead core is easy to rotate. Since the rubber around the bead core is pulled by the rotation of the bead core, stress concentrates around the bead core. As described above, in the conventional technology, when the height of the folded portion is reduced, stress including an input from the rim wheel is concentrated at the end portion of the folded portion, and a large strain occurs at the end portion of the folded portion. There is a risk that the end of the folded portion may break down.

On the other hand, in the present embodiment, the bead core 61 is made of a resin material, so that the rotational rigidity is higher than that in the conventional technique, and thus the rotation of the bead core 61 is suppressed. As a result, the stress including the input from the rim wheel 100 is suppressed from concentrating on the end portion 42a of the folded portion 42. Thereby, the strain generated at the end portion 42a of the folded-back portion 42 is reduced, and the failure of the end portion 42a of the folded-back portion 42 can be prevented. As described above, according to this embodiment, even when the height of the folded-back portion 42 is reduced, the failure of the end portion 42a of the folded-back portion 42 can be prevented. Therefore, according to this embodiment, the weight of the tire 10 can be reduced, and the failure of the end portion 42a of the folded portion 42 can be prevented.

As described above, the embodiments of the present invention have been described, but it should not be understood that the descriptions and drawings forming a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples, and operation techniques will be apparent to those skilled in the art.

For example, the position of the end portion 42a of the folded portion 42 may be set to the position shown in FIG. L1 shown in FIG. 3 is the tire cross-sectional height from the end portion 62b on the tire radial direction inner side of the bead filler 62 to the end portion 62a on the tire radial direction outer side of the bead filler 62. L2 shown in FIG. 3 is the tire cross-sectional height from the end portion 62b of the bead filler 62 on the tire radial inner side to the end portion 42a of the folded portion 42. When L1 and L2 satisfy the relationship of L1 / 2 ≧ L2, the position of the end portion 42a of the folded portion 42 is not limited. Even when the position of the end portion 42a of the folded-back portion 42 is set to the position shown in FIG. 3, the same effect as described above can be obtained. The end portion 62b shown in FIG. 3 may be expressed as the innermost end portion of the bead filler 62 in the tire radial direction.

Further, as shown in FIG. 4, the folded-back portion 42 may be bent inward in the tire width direction and inserted between the bead core 61 and the bead filler 62. Of course, even in this case, the end portion 42a of the folded-back portion 42 is located on the inner side in the tire radial direction with respect to the end portion 62a of the bead filler 62. Also in this case, the same effect as the above-mentioned effect can be obtained.

Further, as shown in FIG. 5, the folded-back portion 42 may be further bent outward in the tire width direction and may be formed along the tire width direction inner surface 63c of the bead filler 62. Of course, even in this case, the end portion 42a of the folded-back portion 42 is located on the inner side in the tire radial direction with respect to the end portion 62a of the bead filler 62. Also in this case, the same effect as the above-mentioned effect can be obtained.

The entire contents of Japanese Patent Application No. 2018-204974 (filing date: October 31, 2018) are incorporated herein by reference.

10 tire 20 tread portion 30 tire side portion 40 carcass 41 body portion 42 folded-

back portions

42a, 62a, 62b end portion 50 belt layer 60 bead portion 61 bead core 61a cord 62 bead filler 63c tire width direction inner side surface 100 rim wheel

Claims

With the tread part in contact with the road surface,
Continuing with the tread portion, a tire side portion located on the tire radial direction inner side of the tread portion,
A bead portion which is continuous with the tire side portion and is located on the tire radial direction inner side of the tire side portion,
A tire including a carcass forming a skeleton of the tire,
The bead portion is
An annular bead core formed by a resin-coated cord and extending in the tire circumferential direction,
A bead filler made of a resin material is disposed adjacent to the tire radial direction outer side of the bead core,
Have
The carcass is
Body part,
Continuing to the main body portion, and having a folded-back portion that is folded back to the outside in the tire width direction via the bead core,
A tire characterized in that an end of the folded-back portion is located on an inner side in the tire radial direction than an end of the bead filler on an outer side in the tire radial direction.
The tire cross-section height from the tire radial inner end of the bead filler to the tire radial outer end of the bead filler is L1, and the folded portion from the tire radial inner end of the bead filler. The tire according to claim 1, wherein L1 and L2 satisfy a relationship of L1 / 2 ≧ L2, where L2 is a tire cross-sectional height up to the end of the tire.
The tire according to claim 1, wherein the folded-back portion is bent inward in the tire width direction and is inserted between the bead core and the bead filler.
The tire according to claim 3, wherein the folded-back portion is further bent toward an outer side in the tire width direction and is formed along an inner side surface in the tire width direction of the bead filler.