JP2021091285A - Pneumatic tire - Google Patents

Abstract

To suppress rolling resistance of a pneumatic tire, and suppress occurrence of separation on a belt end.SOLUTION: A pneumatic tire 10 includes a pair of bead parts 12 embedded with bead cores 22, a carcass ply 14 that straddles the pair of bead parts 12 and includes a body part 14A and a folding-back part 14B, a belt 16 that is provided outside in a tire radial direction of the body part 14A, and is composed of an outside belt layer 26 and an inside belt layer 36 in which a plurality of cords 24 are covered with rubber and the cords 24 cross each other when viewed from the tire radial direction, a tread 18 provided outside in the radial direction of the belt 16, and a reinforcing member 20 that is provided between the outside in the tire radial direction of a tire width direction end 26E of the outside belt layer 26 and the tread 18, and is configured so that a resin-coated cord 32 where a cord 28 is coated with a coating resin 30 having higher tensile elastic modulus than rubber of the belt 16 is spirally wound in a tire circumferential direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pneumatic tire.

For pneumatic tires, for the purpose of improving high-speed durability without reducing wear resistance, both ends of the steel belt layer in the tire width direction are separated between the tread tread and the steel belt layer. Disclosed is a structure provided with a pair of left and right belt end reinforcing layers covering the entire circumference in the tire circumferential direction (see Patent Document 1). The steel belt layer is composed of two steel cord layers. The steel cords embedded in the steel cord layers intersect each other in a plan view of the tread tread.

Japanese Unexamined Patent Publication No. 2008-174003

The end of the belt layer in the tire width direction (belt end) is deformed in the direction away from the carcass when internal pressure is applied, and when traveling on the road surface, it receives a load from the road surface and repeatedly expands and contracts. When the tire generates heat due to such movement of the belt end, there is a concern that rolling resistance may increase and a failure may occur at the belt end. In order to suppress such movement of the belt end, a belt end reinforcing layer as in the above-mentioned conventional example is used.

However, in the above-mentioned conventional example, since the organic fiber cord constituting the belt end reinforcing layer is embedded in the rubber of the tire, the belt end may move according to the deformation of the rubber, and the movement of the belt end may occur. There is room for improvement in terms of restraint.

An object of the present invention is to reduce the rolling resistance of a pneumatic tire and to suppress the occurrence of separation at the belt end.

The pneumatic tire according to the first aspect straddles the pair of bead portions in which the bead cores are embedded and the pair of bead portions, and is located between the bead cores and the main body portion and the bead cores from the inside to the outside in the tire width direction. A carcass ply having a folded-back portion and a carcass ply provided on the outer side of the main body of the carcass ply in the tire radial direction, each of which has a plurality of cords covered with rubber and the cords when viewed from the tire radial direction. A belt composed of an outer belt layer and an inner belt layer arranged so as to intersect each other, a tread provided on the radial outer side of the belt, and a tire radial outer side of the tire width direction end of the outer belt layer. A resin-coated cord provided between the tire and the tread and coated with a coating resin having a tensile elasticity higher than that of the rubber is spirally wound in the tire circumferential direction, and the coating resins are wound in the tire width direction. Has reinforcing members joined to each other.

In this pneumatic tire, a resin-coated cord in which the cord is coated with a coating resin having a tensile elastic modulus higher than that of rubber is placed between the tire radial outer side and the tread at the end of the outer belt layer in the tire width direction in the tire circumferential direction. A reinforcing member is provided which is formed by winding in a spiral shape and in which the coating resins are joined to each other in the tire width direction. Therefore, the movement of the belt layer when the internal pressure is applied or when traveling on the road surface is suppressed. Therefore, heat generation due to the movement of the belt end is reduced. This also reduces the rolling resistance of the pneumatic tire and suppresses the occurrence of separation at the belt end.

In the second aspect, in the pneumatic tire according to the first aspect, the reinforcing member is the end side circumferential main groove farthest from the tire equatorial plane among the circumferential main grooves formed in the tread. Is arranged over at least the region from the outer belt layer to the end of the outer belt layer in the tire width direction.

When the internal pressure of a pneumatic tire is applied or when traveling on a road surface, the region of the belt layer outside the end side circumferential main groove in the tire width direction is compared with the region inside the end side circumferential main groove in the tire width direction. Easy to move. In this pneumatic tire, the reinforcing member is arranged over the region from the main groove in the peripheral direction at the end to at least the end of the outer belt layer in the tire width direction, so that the movement of the belt end of the outer belt layer is further increased. Can be suppressed.

In the third aspect, in the pneumatic tire according to the second aspect, the end of the inner belt layer in the tire width direction is located on the outer side of the outer belt layer in the tire width direction with respect to the end of the outer belt layer in the tire width direction. The outer end of the reinforcing member in the tire width direction is located between the end of the outer belt layer in the tire width direction and the end of the inner belt layer in the tire width direction.

In this pneumatic tire, the outer end of the reinforcing member in the tire width direction is located between the end of the outer belt layer in the tire width direction and the end of the inner belt layer in the tire width direction. Not only the movement of the belt end but also the movement of the belt end of the inner belt layer can be suppressed.

In the fourth aspect, in the pneumatic tire according to any one of the first to third aspects, a belt protective layer covering the belt is provided on the outer side in the tire radial direction of the belt, and the reinforcing member comprises the reinforcing member. The belt protective layer is provided on the outer side in the tire radial direction.

Since this pneumatic tire is provided with a belt protective layer that covers the belt, it is possible to protect the belt from foreign matter and improve the puncture resistance performance.

According to the present invention, it is possible to reduce the rolling resistance of a pneumatic tire and suppress the occurrence of separation at the belt end.

It is a half cross-sectional view which shows one side of the tire equatorial plane about an example of a pneumatic tire which concerns on this embodiment. It is a partial fracture perspective view which shows the structure near the belt end. It is a half cross-sectional view which shows one side of the tire equatorial plane about another example of a pneumatic tire which concerns on this embodiment.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The arrow W shown in the figure indicates the tire width direction (hereinafter, “tire width direction”), and the arrow R indicates the tire radial direction (hereinafter, “tire radial direction”). Here, the tire width direction is a direction parallel to the tire rotation axis, and the tire radial direction is a direction orthogonal to the tire rotation axis. The reference numeral CL indicates the equatorial plane of the tire.

In FIGS. 1 and 2, the pneumatic tire 10 according to the present embodiment is, for example, a so-called radial tire used in a passenger car, and includes a pair of bead portions 12, a carcass ply 14, a belt 16, and a tread 18. It has a reinforcing member 20. A bead core 22 is embedded in the bead portion 12.

The carcass ply 14 straddles a pair of bead portions 12 and has a main body portion 14A located between the bead cores 22 and a folded-back portion 14B of the bead core 22 wound from the inside to the outside in the tire width direction. The tip of the folded-back portion 14B extends, for example, to the inside of the belt 16 in the tire radial direction, and is sandwiched between the belt 16 and the main body portion 14A. The folded-back portion 14B may not be sandwiched between the belt 16 and the main body portion 14A.

The carcass ply 14 is formed by coating a plurality of cords (not shown) extending in the radial direction of the pneumatic tire 10 with coated rubber (not shown). The material of the cord of the carcass ply 14 is, for example, PET, but other conventionally known materials may be used.

A bead filler 40 is provided in a portion surrounded by the carcass ply 14 and the bead core 22. Further, as an example, a reinforcing member 42 is provided inside the bead filler 40 in the tire width direction along the main body portion 14A of the carcass ply 14.

The belt 16 is provided on the outer side of the main body portion 14A of the carcass ply 14 in the tire radial direction. As shown in FIG. 2, in the belt 16, a plurality of cords 24 are each covered with rubber, and the outer belt layer 26 and the inner belt 36 are arranged so that the cords 24 intersect with each other when viewed from the tire radial direction. It is composed of. That is, the belt 16 is a rubber belt having a so-called two-layer interlaced structure. In the illustrated example, the end of the inner belt 36 in the tire width direction (hereinafter referred to as "belt end 36A") is the end of the outer belt layer 26 in the tire width direction (hereinafter referred to as "belt end 26A"). It is located on the outside in the tire width direction. In other words, the inner belt 36 is configured to be wider than the outer belt layer 26.

The tread 18 is a portion provided on the radial outer side of the belt 16 and mainly constitutes a ground contact portion. For example, two main grooves 38 in the circumferential direction are formed on both sides of the tire equatorial plane CL of the tread 18 in the tire width direction. In the present embodiment, the circumferential main groove 38 close to the tire equatorial plane CL is referred to as the central circumferential main groove 38A, and the circumferential main groove 38 farthest from the tire equatorial plane CL is referred to as the end side circumferential main groove 38B. Call.

The reinforcing member 20 is provided between the tire radial outer side of the tire width direction end portion 26E of the outer belt layer 26 and the tread 18. The reinforcing member 20 is configured by spirally winding a resin-coated cord 32 in which the cord 28 is coated with a coating resin 30 having a tensile elastic modulus higher than that of rubber in the tire circumferential direction. The coating resins 30 are joined to each other in the tire width direction by, for example, heat welding. In the illustrated example, two cords 28 are used for one resin-coated cord 32, but the number of cords 28 is not limited to this. The cross-sectional shape of the coating resin 30 is, for example, a parallelogram, but other cross-sectional shapes may be used.

The reinforcing member 20 is arranged over a region from the end-side circumferential main groove 38B formed in the tread 18 to at least the belt end 26A of the outer belt layer 26. That is, this region corresponds to the end portion 26E of the outer belt layer 26 in the tire width direction. Although not shown, the outer end 20A of the reinforcing member 20 in the tire width direction may be located between the belt end 26A of the outer belt layer 26 and the belt end 36A of the inner belt 36. In other words, the outer end 20A of the reinforcing member 20 in the tire width direction may protrude further outward in the tire width direction than the belt end 26A of the outer belt layer 26.

Here, as the resin used for the coating resin 30, a thermoplastic resin can be used, and a resin material having a tensile elastic modulus higher than that of the rubber constituting the belt 16 and the rubber constituting the tread 18 is used. .. As this resin, a thermoplastic resin having elasticity and a thermoplastic elastomer (TPE or the like can be used. Considering elasticity during running and moldability during production, 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 more, and the tension specified in JIS K7113. The yield strength is 10 [MPa] or more, the tensile fracture elongation specified in JIS K7113 is 50% or more, and the deflection temperature (A method) specified in JIS K7206 is 130 [° C] or more. be able to.

The tensile elastic modulus (specified in JIS K7113: 1995) of the resin used for the coating resin 30 is preferably 100 [MPa] or more. The upper limit of the tensile elastic modulus of the resin used for the coating resin 30 is preferably 1000 [MPa] or less, and particularly preferably in the range of 200 to 700 [MPa].

An adhesive resin (not shown) is provided between the cord 28 and the coating resin 30. As the resin used for the adhesive resin, a thermoplastic resin can be used, and a resin that is more difficult for water to permeate than the coating resin 30, in other words, a resin that is harder to absorb water is used. Examples of the adhesive constituting the resin material used for the adhesive resin include modified olefin resins (modified polyethylene resins, modified polypropylene resins, etc.), polyamide resins, polyurethane resins, polyester resins, and modified polyester resins. , Ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer and the like containing one or more kinds of thermoplastic resins as a main component (main agent).

Among these, from the viewpoint of adhesiveness to the metal member (code 28) and the resin layer (coating resin 30), modified olefin resin, polyester resin, modified polyester resin, ethylene-ethyl acrylate copolymer, and A hot melt adhesive containing at least one selected from the group consisting of ethylene-vinyl acetate copolymers is preferable, and a hot melt adhesive containing at least one selected from a modified olefin resin and a modified polyester resin is more preferable. Among them, a hot melt adhesive containing at least one selected from an acid-modified olefin resin (modified olefin resin acid-modified with an unsaturated carboxylic acid) and a modified polyester resin is more preferable, and the acid-modified polyester resin is included. Hot melt adhesives are particularly preferred.

Here, the "modified olefin resin acid-modified with an unsaturated carboxylic acid" means a modified olefin resin obtained by graft-copolymerizing an unsaturated carboxylic acid with a polyolefin.

As shown in FIG. 3, a belt protective layer 34 covering the belt 16 may be provided on the outer side of the belt 16 in the tire radial direction. The belt protective layer 34 is formed, for example, by coating organic fibers with rubber to form a sheet. In this case, the reinforcing member 20 is provided, for example, on the outer side of the belt protective layer 34 in the tire radial direction. That is, the belt protection layer 34 is arranged between the outer belt layer 26 and the reinforcing member 20. The belt protection layer 34 may be arranged outside the belt 16 and the reinforcing member 20 in the tire radial direction.

(Action)
This embodiment is configured as described above, and its operation will be described below. In FIGS. 1 and 2, in the pneumatic tire 10 according to the present embodiment, a coating having a tensile elastic modulus higher than that of rubber is formed between the tire radial outer side of the tire width direction end portion 26E of the outer belt layer 26 and the tread 18. A reinforcing member 20 is provided, which is formed by spirally winding a resin-coated cord 32 coated with a resin 30 in the tire circumferential direction, and the coated resins 30 are joined to each other in the tire width direction.

Specifically, when the internal pressure of the pneumatic tire is applied or when the tire is running on the road surface, the region of the belt 16 outside the end side circumferential direction main groove 38B to the tire width direction is the tire from the end side circumferential direction main groove 38B. It is easier to move than the area inside in the width direction. In the present embodiment, the reinforcing member 20 is arranged in a region from the end side circumferential main groove 38B to at least the belt end 26A of the outer belt layer 26. Therefore, the movement of the belt 16 when the internal pressure is applied or when traveling on the road surface is suppressed. Therefore, heat generation due to the movement of the belt end is reduced. Further, this reduces the rolling resistance of the pneumatic tire 10 and suppresses the occurrence of separation at the belt end.

Although not shown, when the outer end 20A of the reinforcing member 20 in the tire width direction is located between the belt end 26A of the outer belt layer 26 and the belt end 36A of the inner belt 36, the outer belt layer 26 Not only the movement of the belt end but also the movement of the belt end of the inner belt 36 can be suppressed.

As described above, according to the present embodiment, it is possible to reduce the rolling resistance of the pneumatic tire 10 and suppress the occurrence of separation at the belt end.

Further, as shown in FIG. 3, when a belt protective layer 34 covering the belt 16 is provided on the outer side of the belt 16 in the tire radial direction, the belt 16 is protected from foreign matter and the puncture resistance is improved. Can be done.

[Other Embodiments]
Although an example of the embodiment of the present invention has been described above, the embodiment of the present invention is not limited to the above, and other than the above, various modifications can be made within a range not deviating from the gist thereof. Of course there is.

It is assumed that the reinforcing member 20 is arranged over a region from the end side circumferential main groove 38B formed in the tread 18 to at least the belt end 26A of the outer belt layer 26, but the reinforcing member 20 is not limited to this. 20 may be located in a narrower area in the area.

Although the belt 16 is a rubber belt having a two-layer interlaced structure, the structure of the belt 16 is not limited to this, and various known belt structures can be used.

10 ... Pneumatic tire, 12 ... Bead part, 14 ... Carcass ply, 14A ... Main body part, 14B ... Folded part, 16 ... Belt, 18 ... Tread, 20 ... Reinforcing member, 20A ... Outer end in tire width direction, 22 ... Bead core, 24 ... cord, 26 ... outer belt, 26A ... belt end (end in tire width direction), 26E ... tire width direction end, 28 ... cord, 30 ... coating resin, 32 ... resin coating cord, 34 ... belt protection Layer, 36 ... Inner belt, 36A ... Belt end (end in tire width direction), 38 ... Circumferential main groove, 38B ... End side circumferential main groove

Claims (4)

A pair of bead parts with embedded bead cores,
A carcass ply that straddles the pair of bead portions and has a main body portion located between the bead cores and a folded portion that is wound from the inside to the outside in the tire width direction of the bead core.
An outer belt layer and an inner side provided on the outer side of the main body of the carcass ply in the tire radial direction, each of which has a plurality of cords covered with rubber and arranged so that the cords intersect each other when viewed from the tire radial direction. A belt composed of a belt layer and
A tread provided on the radial outer side of the belt and
A resin-coated cord provided between the tire radial outer end of the outer belt layer in the tire width direction and the tread and coated with a coating resin having a tensile elastic modulus higher than that of the rubber is spiraled in the tire circumferential direction. Reinforcing members that are wound around in a shape and the coating resins are joined to each other in the tire width direction.
Pneumatic tires with. The reinforcing member extends from the peripheral main groove formed on the tread to the end side peripheral main groove farthest from the tire equatorial plane to at least the end of the outer belt layer in the tire width direction. The pneumatic tire according to claim 1, which is arranged. The end of the inner belt layer in the tire width direction is located outside the end of the outer belt layer in the tire width direction in the tire width direction.
The pneumatic tire according to claim 2, wherein the outer end of the reinforcing member in the tire width direction is located between the end of the outer belt layer in the tire width direction and the end of the inner belt layer in the tire width direction. A belt protective layer covering the belt is provided on the outer side of the belt in the tire radial direction.
The pneumatic tire according to any one of claims 1 to 3, wherein the reinforcing member is provided on the outer side of the belt protective layer in the tire radial direction.

Images