JP7099932B2 - tire - Google Patents

Description

The present invention relates to a tire.

Generally, the carcass, which is a member forming the skeleton of a tire, is connected to a main body portion extending in a toroid shape straddling between a pair of bead cores and is connected to the main body portion, and is folded outward in the tire width direction via the bead core. It has a folded portion (Patent Document 1).

The main body portion and the folded portion of the carcass 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 outer side from the tire radial 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, tires are also required to be lighter. 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, when the height of the folded portion is lowered, the input from the rim wheel is concentrated on the end portion of the folded portion, and a large strain is generated at the end portion of the folded portion. This may cause the end of the folded portion to fail.

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

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

According to the tire described above, even when the height of the folded portion is lowered, it is possible to prevent the end portion of the folded portion from failing.

FIG. 1 is a cross-sectional view taken along the tire width direction and the tire radial direction of the tire. 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.

Hereinafter, embodiments of the present invention will be described 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 the tire 10 along the tire width direction and the tire radial direction. In FIG. 1, the cross-sectional hatching is not shown (the same applies hereinafter).

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). A pattern (not shown) is formed on the tread portion 20 according to the usage environment of the tire 10 and the type of vehicle to be mounted.

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 a region from the outer end of the tread portion 20 in the tire width direction 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) arranged radially along the tire radial direction. However, the carcass 40 is not limited to the radial structure, and may be 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 inside the tread portion 20 in the tire radial direction. As shown in FIG. 1, the belt layer 50 is a resin-coated single-layer spiral belt. As the resin material constituting the belt layer 50, a resin material described later is used. 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 crossed belt.

The bead portion 60 is connected to 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 inside in the tire width direction to the outside in the tire width direction 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 outward in the tire width direction via the bead portion 60. Specifically, the carcass 40 includes a main body portion 41 and a folded portion 42.

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

The folded-back portion 42 is a portion connected to the main body portion 41 and folded outward in the tire width direction via the bead core 61.

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

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

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

Examples of the thermoplastic elastomer include polyolefin-based thermoplastic elastomer (TPO), polystyrene-based thermoplastic elastomer (TPS), polyamide-based thermoplastic elastomer (TPA), polyurethane-based thermoplastic elastomer (TPU), and polyester-based thermoplastic elastomer (TPC). , Dynamic cross-linked thermoplastic elastomer (TPV) and the like.

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 (at 0.45 MPa load) specified in ISO75-2 or ASTM D648 is 78 ° C or higher, and the tensile yield strength specified in JIS K7113 is 10 MPa. As described above, those having a tensile fracture elongation (JIS K7113) specified in JIS K7113 of 50% or more and a Bikat softening temperature (method A) specified in JIS K7206 of 130 ° C. or more can be used.

The bead filler 62 has a triangular shape in which the thickness gradually decreases toward the outside in the tire radial direction. Further, 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 inside the tire radial direction with respect to the tire radial 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 outer surface of the bead filler 62 in the tire width direction.

(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 inside the tire radial direction from the end portion 62a outside the tire radial direction of the bead filler 62. That is, the height of the folded-back portion 42 (tire cross-sectional height) in the present embodiment is lower than that of the prior art. As a result, the amount of material forming the carcass 40 is reduced, so that the weight of the tire 10 can be reduced. Further, in the present embodiment, the bead core 61 is formed of a resin material, and the bead filler 62 adjacent to the bead core 61 is also formed of a resin material. As described above, the elastic modulus of the resin material is higher than the elastic modulus of the rubber material, so that the rotation of the bead core 61 is suppressed. This point will be described below in comparison with the prior art.

When the bead part collapses when the side part is deformed due to the tire contact load, or when the lateral force toward the inside of the turn acts on the tire from the road surface when the car turns, the outer part of the bead part in the tire width direction turns. When the sidewall portion slides inward on the rim wheel and the sidewall portion is greatly collapsed inward due to the moment based on the lateral force, a force in the rotation direction of the bead core is generated. When the bead core (excluding the cord part) is made of a rubber material as in the prior art, the rotational rigidity of the bead core is lower than when the bead core (excluding the cord part) is made of a resin material. The bead core is easy to rotate. The rotation of the bead core pulls the rubber around the bead core, so that stress is concentrated around the bead core. As described above, in the prior art, when the height of the folded portion is lowered, the stress including the input from the rim wheel is concentrated on the end of the folded portion, and a large strain is generated at the end of the folded portion. The end of the folded part may break down.

On the other hand, in the present embodiment, since the bead core 61 is made of a resin material, the rotational rigidity is higher than that of the prior art, so that 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 being concentrated on the end portion 42a of the folded portion 42. As a result, the strain generated at the end portion 42a of the folded portion 42 can be reduced, and the failure of the end portion 42a of the folded portion 42 can be prevented. As described above, according to the present embodiment, even if the height of the folded-back portion 42 is lowered, the failure of the end portion 42a of the folded-back portion 42 can be prevented. Therefore, according to the present embodiment, the weight of the tire 10 can be reduced, and the failure of the end portion 42a of the folded-back portion 42 can be prevented.

As mentioned above, embodiments of the invention have been described, but the statements and drawings that form part of this disclosure should not be understood to limit the invention. This disclosure will reveal to those skilled in the art various alternative embodiments, examples and operational techniques.

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 tire radial inner end 62b of the bead filler 62 to the tire radial outer end 62a of the bead filler 62. Further, L2 shown in FIG. 3 is the tire cross-sectional height from the end portion 62b on the inner side in the tire radial direction of the bead filler 62 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-back 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 inside the end portion 62a of the bead filler 62 in the tire radial direction. Further, even 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 toward the outer side in the tire width direction and may be formed along the inner side surface 63c in the tire width direction of the bead filler 62. Of course, even in this case, the end portion 42a of the folded-back portion 42 is located inside the end portion 62a of the bead filler 62 in the tire radial direction. Further, even in this case, the same effect as the above-mentioned effect can be obtained.

10 Tire 20 Tread part 30 Tire side part 40 Carcass 41 Main body part 42 Folded part 42a, 62a, 62b End part 50 Belt layer 60 Bead part 61 Bead core 61a Code 62 Bead filler 63c Tire width direction inner side surface 100 Rim wheel

Claims (4)

The tread part that touches the road surface and
A tire side portion that is connected to the tread portion and is located inside the tread portion in the tire radial direction.
A bead portion that is connected to the tire side portion and is located inside the tire side portion in the tire radial direction.
A tire that includes a carcass that forms the 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, which is arranged adjacent to the outer side of the bead core in the tire radial direction,
Have,
The carcass is
With the main body
It has a folded portion that is connected to the main body portion and is folded outward in the tire width direction via the bead core.
A tire characterized in that the end portion of the folded portion is located inside the tire radial direction from the end portion of the bead filler on the outer side in the tire radial direction. The tire cross-sectional 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 the relationship of L1 / 2 ≧ L2, where L2 is the cross-sectional height of the tire to the end of the tire. The tire according to claim 1, wherein the folded portion is bent inward in the tire width direction and inserted between the bead core and the bead filler. The tire according to claim 3, wherein the folded portion is further bent toward the outside in the tire width direction and is formed along the inner side surface of the bead filler in the tire width direction.

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