WO2019220889A1

WO2019220889A1 - Pneumatic tire

Info

Publication number: WO2019220889A1
Application number: PCT/JP2019/017257
Authority: WO
Inventors: 誓志今; 好秀河野
Original assignee: 株式会社ブリヂストン
Priority date: 2018-05-14
Filing date: 2019-04-23
Publication date: 2019-11-21
Also published as: JP2019199106A

Abstract

A pneumatic tire according to the present invention is provided with: a pair of bead cores; a carcass which is formed so as to extend across the pair of bead cores; a belt layer which is formed by spirally winding a covered cord (a rubber-covered cord) in the tire circumferential direction, said covered cord being formed by covering a cord (a reinforcement cord) with a rubber (a covering rubber), and which is arranged on the outside of the carcass in the tire radial direction; a resin reinforcement layer which is arranged on the outside or inside of the belt layer in the tire radial direction; and a tread which is arranged on the outside of the belt layer and the resin reinforcement layer in the tire radial direction.

Description

Pneumatic tire

This disclosure relates to a pneumatic tire provided with a belt layer.

Japanese Unexamined Patent Application Publication No. 2016-193725 describes an automobile tire in which a working reinforcing material is formed by winding a plurality of reinforcing rubber strips formed using a steel cord in the tire circumferential direction.

In the automobile tire disclosed in Japanese Patent Laid-Open No. 2016-193725, the end surfaces of a plurality of steel cords are exposed at the end portion of the actual reinforcing material in the tire width direction. Generally, the end surface of the steel cord is not plated. For this reason, it is difficult to bond the place where the end surface of the steel cord is exposed in the actual reinforcing material and the rubber forming the tread. Thereby, the actual reinforcing material (belt layer) and the rubber forming the tread are easily peeled off.

Also, the steel cord is cut along a direction inclined with respect to the extending direction of the steel cord. For this reason, the tip of the steel cord is formed sharper than, for example, the tip of the steel cord cut along a direction orthogonal to the extending direction. For this reason, the rubber forming the tread is easily damaged. As a result, the actual reinforcing material (belt layer) and the rubber forming the tread are more easily separated.

The present disclosure provides a pneumatic tire in which a belt layer and a member covering the belt layer are hardly peeled off.

The pneumatic tire according to the first aspect includes a pair of bead cores, a carcass formed across the pair of bead cores, and a coated cord formed by covering the cord with rubber on the outer side in the tire radial direction of the carcass. A belt layer formed by being spirally wound in the circumferential direction, a resin reinforcing layer disposed on the outer side or the inner side in the tire radial direction of the belt layer, and provided on the outer side in the tire radial direction of the belt layer and the resin reinforcing layer. Tread.

According to the pneumatic tire of the first aspect, the resin reinforcing layer is arranged on the outer side or the inner side of the belt layer in the tire radial direction. Thereby, the tread is reinforced by the resin reinforcing layer. The tread reinforced by the resin reinforcing layer has higher ring rigidity than the non-reinforced tread. For this reason, it becomes difficult for the tread to be deformed out of the plane of the annular surface along the tire circumferential direction and the tire width direction, and deformation of the pneumatic tire is suppressed.

Further, when the resin reinforcing layer is arranged, in-plane (in the annular plane along the tire circumferential direction and the tire width direction) shear rigidity is higher than when the resin reinforcing layer is not arranged. For this reason, for example, during turning, the tread is difficult to be deformed in-plane due to the shearing force acting in the tire width direction. As a result, the crossing belt layer can be omitted, so that the weight of the tire is reduced, and the steering stability during running under internal pressure is increased.

Furthermore, the belt layer is formed by spirally winding a coated cord formed by coating the cord with rubber in the tire circumferential direction. For this reason, it is difficult to expose the end face of the cord at the end of the belt layer in the tire width direction. Thereby, the belt layer and the tread or the resin reinforcing layer covering the belt layer are hardly peeled off.

On the other hand, for example, when a belt layer is formed by arranging a plurality of cords inclined with respect to the tire circumferential direction, the end surface of the cord is likely to be exposed at the end of the belt layer in the tire width direction. The end surface of the cord is less likely to adhere to members around the cord layer as compared to the outer peripheral surface of the cord. For this reason, a belt layer and the tread which covers a belt layer, or a resin reinforcement layer becomes easy to peel.

In the pneumatic tire of the second aspect, the inclination angle of the covering cord with respect to the tire circumferential direction is 10 ° or less on the tire equatorial plane.

According to the pneumatic tire of the second aspect, the inclination angle of the covering cord is closer to the circumferential direction on the tire equatorial plane than when the inclination angle of the covering cord with respect to the tire circumferential direction is larger than 10 °. As a result, the covering cord exhibits a function as a gutter and can suppress out-of-plane deformation of the tread.

In the pneumatic tire of the third aspect, the end portion in the tire width direction of the resin reinforcing layer is disposed on the outer side in the tire width direction from the end portion in the tire width direction of the belt layer.

According to the pneumatic tire of the third aspect, since the resin reinforcing layer is formed wider than the belt layer, the belt layer is hardly deformed. Specifically, when the resin reinforcing layer is located on the inner side in the tire radial direction from the belt layer, the belt layer is stiffened by the resin reinforcing layer even if it is deformed inward in the tire radial direction by receiving an external force, and the belt layer is deformed. Is suppressed. Further, when the resin reinforcing layer is on the outer side in the tire radial direction from the belt layer, the resin reinforcing layer suppresses the input of external force to the belt layer, so that deformation of the belt layer is suppressed. This makes it difficult for the belt layer to break.

According to the pneumatic tire according to the present disclosure, the belt layer and the member covering the belt layer are difficult to peel off.

It is a half sectional view showing the state where a pneumatic tire concerning an embodiment of this indication was cut along a tire width direction and a tire radial direction. It is a perspective view showing composition of a belt layer in a pneumatic tire concerning an embodiment of this indication. It is sectional drawing which shows the belt layer in the pneumatic tire which concerns on embodiment of this indication. FIG. 6 is a cross-sectional view illustrating a modification in which a plurality of reinforcing cords are embedded in one rubber-coated cord in a pneumatic tire according to an embodiment of the present disclosure. It is the elements on larger scale which showed the inclination-angle in the tire equatorial plane of the rubber coating cord in the belt layer which concerns on embodiment of this indication. FIG. 6 is a half cross-sectional view illustrating a modification in which a resin reinforcing layer is formed wider than a belt layer in a pneumatic tire according to an embodiment of the present disclosure. FIG. 6 is a half cross-sectional view showing a modification in which a resin reinforcing layer is disposed on the inner side in the tire radial direction of a belt layer in a pneumatic tire according to an embodiment of the present disclosure. In the pneumatic tire concerning the embodiment of this indication, it is a key map showing the angle of inclination in the case of making a rubber covering cord wind only 1 turn around a carcass. It is a conceptual diagram which shows the inclination angle in the case of forming a belt layer with one rubber-coated cord in the pneumatic tire according to the embodiment of the present disclosure. It is an expanded view of the belt layer which concerns on a comparative example. FIG. 8B is a sectional view taken along line BB in FIG. 8A.

FIG. 1 shows a cut surface (that is, a direction along a tire circumferential direction) cut along a tire width direction and a tire radial direction of a pneumatic tire (hereinafter referred to as “tire 10”) according to an embodiment of the present disclosure. One side of the cross section viewed from FIG. In the figure, an arrow W indicates the width direction of the tire 10 (tire width direction), and an arrow R indicates the radial direction of the tire 10 (tire radial direction). The tire width direction here refers to a direction parallel to the rotation axis of the tire 10. Further, the tire radial direction refers to a direction orthogonal to the rotation axis of the tire 10. Reference sign CL indicates the equator plane of the tire 10 (tire equator plane).

In the present embodiment, the side closer to the rotation axis of the tire 10 along the tire radial direction is “inner side in the tire radial direction”, and the side farther from the rotation axis of the tire 10 along the tire radial direction is “outer side in the tire radial direction”. It describes. On the other hand, the side close to the tire equator plane CL along the tire width direction is described as “inner side in the tire width direction”, and the side far from the tire equator plane CL along the tire width direction is described as “outer side in the tire width direction”.

(tire)
FIG. 1 shows a tire 10 when it is assembled to a rim 30 that is a standard rim and filled with standard air pressure. Here, the “standard rim” refers to a rim defined in the Year Book 2017 version of JATMA (Japan Automobile Tire Association). The standard air pressure is an air pressure corresponding to the maximum load capacity of Year Book 2017 version of JATMA (Japan Automobile Tire Association).

As shown in FIG. 1, the tire 10 includes a pair of bead portions 12, a carcass 14 having an end portion locked to the bead core 12 </ b> A embedded in each bead portion 12, and a bead portion 12. A bead filler 12B that is buried and extends along the outer surface of the carcass 14 from the bead core 12A to the outer side in the tire radial direction, a belt layer 40 provided on the outer side in the tire radial direction of the carcass 14, and a outer side in the tire radial direction of the belt layer 40. The resin reinforcing layer 50 and a tread 60 provided on the outer side in the tire radial direction of the resin reinforcing layer 50 are provided. In FIG. 1, only the bead portion 12 on one side is shown.

(Bead part)
In the pair of bead portions 12, bead cores 12A as wire bundles are respectively embedded. A carcass 14 straddles these bead cores 12A. The bead core 12A can employ various structures such as a circular cross section and a polygonal cross section. Further, for example, a hexagon can be adopted as the polygon, but in the present embodiment, it is a quadrangle.

A bead filler 12B extending from the bead core 12A to the outer side in the tire radial direction is embedded in a region surrounded by the carcass 14 locked to the bead core 12A in the bead portion 12.

(Carcass)
The carcass 14 is a tire frame member formed by coating a plurality of cords with a covering rubber. The carcass 14 extends in a toroidal shape from one bead core 12A to the other bead core 12A to form a tire skeleton. Further, the end portion side of the carcass 14 is locked to the bead core 12A. Specifically, the end of the carcass 14 is folded and locked around the bead core 12A from the inner side in the tire width direction to the outer side in the tire width direction.

In the present embodiment, the carcass 14 is a radial carcass. The material of the carcass 14 is not particularly limited, and rayon, nylon, polyethylene naphthalate (PEN), polyethylene terephthalate (PET), aramid, glass fiber, carbon fiber, steel, or the like can be used. From the viewpoint of weight reduction, an organic fiber cord is preferable. In addition, the number of carcass shots is in the range of 20 to 60 pieces / 50 mm, but is not limited to this range.

Side rubber 16 is provided on the outer side of the carcass 14 in the tire width direction. The side rubber 16 extends from the bead portion 12 to the outer side in the tire radial direction to form the side portion 10A of the tire 10 and is joined to the tread 60. Further, the side rubber 16 is formed so that the thickness gradually decreases in the shoulder portion 10B. The end portion 16E of the side rubber 16 is on the inner side in the tire radial direction of the belt layer 40, which will be described later, and on the inner side in the tire width direction from the tire width direction end portion 40EW of the belt layer 40 and the tire width direction end portion 50EW of the resin reinforcing layer 50. Has been placed.

The end 16E of the side rubber 16 may be disposed outside the end 40EW in the tire width direction of the belt layer 40. In this case, the tire width direction end portion 40EW of the belt layer 40 is disposed so as to contact the outer peripheral surface of the carcass 14 instead of the side rubber 16.

(Belt layer)
A belt layer 40 is disposed outside the carcass 14 in the tire radial direction. As shown in FIG. 2, the belt layer 40 is a ring-shaped ridge formed by a single rubber-coated cord 42 spirally wound around the outer circumferential surface of the carcass 14 in the tire circumferential direction. is there. Both end portions 42E1 and 42E2 of the rubber-coated cord 42 are arranged at different positions in the tire circumferential direction. Note that “spiral” indicates a state in which one rubber-coated cord 42 is wound at least one turn around the carcass 14.

As shown in FIG. 3A, the rubber-coated cord 42 is configured by covering a reinforcing cord 42C with a coated rubber 42S, and has a substantially square cross section. The covering rubber 42S is joined to the outer peripheral surfaces of the carcass 14 and the side rubber 16 disposed on the inner side in the tire radial direction via rubber or an adhesive.

Further, the rubbers 42S that are adjacent to each other in the tire width direction are joined to each other during tire vulcanization. As a result, a belt layer 40 (rubber-coated belt layer) in which the reinforcing cord 42C is covered with the covering rubber 42S is formed. As shown in FIG. 2, at the end portions 42E1 and 42E2 of the rubber-coated cord 42, the end surface of the reinforcing cord 42C is exposed. The end portions 42E1 and 42E2 of the rubber-coated cord 42 are formed substantially at right angles to the longitudinal direction of the rubber-coated cord.

FIG. 4 shows a partially enlarged view of the belt layer 40 as seen from the direction along the tire radial direction. As shown in FIG. 4, the rubber-coated cord 42 is wound at an angle θ1 with respect to the tire circumferential direction (the direction indicated by the arrow S in FIG. 4) on the tire equatorial plane. The angle θ1 is 10 ° or less in the present embodiment, but is more preferably 2 ° or less.

Further, the reinforcing cord 42C in the belt layer 40 of the present embodiment is a steel cord whose outer peripheral surface is plated with cobalt. The steel cord is mainly composed of steel and can contain various trace contents such as carbon, manganese, silicon, phosphorus, sulfur, copper, and chromium. The plating material is not limited to cobalt, and nickel or the like can be used. The end surface of the reinforcing cord 42C is not plated, and the solid steel is exposed.

The embodiment of the present disclosure is not limited to this, and the reinforcing cord 42C in the belt layer 40 may be a monofilament cord or a cord in which a plurality of filaments are twisted instead of the steel cord. Further, organic fibers such as aramid, carbon, and the like may be used. Various designs can be adopted for the twist structure, and various cross-sectional structures, twist pitches, twist directions, and distances between adjacent filaments can be used. Furthermore, a cord in which filaments of different materials are twisted can be adopted, and the cross-sectional structure is not particularly limited, and various twisted structures such as single twist, layer twist, and double twist can be adopted.

(Resin reinforcement layer)
As shown in FIG. 1, a resin reinforcing layer 50 is disposed outside the belt layer 40 in the tire radial direction. The resin reinforcing layer 50 is a rigidity imparting member in the tire 10. The width direction end portion 50EW of the resin reinforcing layer 50 is disposed on the inner side in the tire width direction than the width direction end portion 40EW of the belt layer 40. Therefore, both end portions 42E1 and 42E2 (see FIG. 2) of the rubber-coated cord 42 are not covered with the resin reinforcing layer 50 but are covered with the tread rubber 60G that forms the tread 60.

The belt layer 40 and the resin reinforcing layer 50 and the resin reinforcing layer 50 and the tread 60 are bonded with an adhesive or rubber.

The resin material used for the resin reinforcing layer 50 is a thermoplastic resin. However, the embodiment of the present disclosure is not limited thereto, and examples of the resin material include thermoplastic elastomers, thermosetting resins, (meth) acrylic resins, EVA resins, vinyl chloride resins, fluorine resins, and silicone resins. In addition to general-purpose resins, engineering plastics (including super engineering plastics) can be used. The resin material here does not include vulcanized rubber.

Thermoplastic resin (including thermoplastic elastomer) refers to a polymer compound that softens and flows as the temperature rises and becomes relatively hard and strong when cooled. In the present specification, among these, the material softens and flows as the temperature rises, and when cooled, the material becomes relatively hard and strong and has a rubber-like elasticity as a thermoplastic elastomer. Further, when the material softens and flows as the temperature rises, it becomes relatively hard and strong when cooled, and a high molecular compound having no rubber-like elasticity is distinguished from a thermoplastic elastomer as a non-elastomer thermoplastic resin.

Thermoplastic resins (including thermoplastic elastomers) include polyolefin-based thermoplastic elastomers (TPO), polystyrene-based thermoplastic elastomers (TPS), polyamide-based thermoplastic elastomers (TPA), polyurethane-based thermoplastic elastomers (TPU), and polyesters. Thermoplastic thermoplastic elastomer (TPC), dynamically crosslinked thermoplastic elastomer (TPV), polyolefin thermoplastic resin, polystyrene thermoplastic resin, polyamide thermoplastic resin, polyester thermoplastic resin, etc. Can be mentioned.

The thermosetting resin refers to a polymer compound that forms a three-dimensional network structure as the temperature rises and cures, and examples thereof include a phenol resin, an epoxy resin, a melamine resin, and a urea resin.

(tread)
A tread 60 is provided outside the resin reinforcing layer 50 in the tire radial direction. The tread 60 is a part that contacts the road surface during traveling, and a plurality of circumferential grooves 62 extending in the tire circumferential direction are formed on the tread surface of the tread 60. The shape and number of the circumferential grooves 62 are appropriately set according to the performance such as drainage performance and steering stability required for the tire 10.

(Function)
According to the tire 10 according to the present embodiment, the resin reinforcing layer 50 is disposed on the outer side in the tire radial direction of the belt layer 40. Thereby, the tread 60 is reinforced by the resin reinforcing layer 50. The tread 60 reinforced by the resin reinforcing layer 50 has higher ring rigidity than a tread that is not reinforced. For this reason, it becomes difficult for the tread 60 to be deformed outside the annular surface along the tire circumferential direction and the tire width direction, and deformation of the tire 10 is suppressed.

Also, the tire 10 has higher shear rigidity in the plane of the tread 60 (that is, in the annular plane along the tire circumferential direction and the tire width direction) than when the resin reinforcing layer 50 is not disposed. For this reason, for example, during turning, the tread 60 is unlikely to be deformed in-plane due to the shearing force acting in the tire width direction. As a result, the crossing belt layer can be omitted, so that the weight of the tire is reduced, and the steering stability during running under internal pressure is increased.

Further, the belt layer 40 is formed by spirally winding a single rubber-coated cord 42 formed by coating the reinforcing cord 42C with the covering rubber 42S in the tire circumferential direction. For this reason, the end surface of the reinforcing cord 42C is exposed at the tire width direction end portion 40EW of the belt layer 40 only at the two ends 42E1 and 42E2 of one rubber-coated cord 42. Thereby, the belt layer 40 and the tread rubber 60 </ b> G covering the belt layer 40 are difficult to peel off.

On the other hand, the belt layer 400 according to the comparative example shown in FIG. 8A is formed by arranging a plurality of rubber-coated cords 420 inclined at an angle θ2 with respect to the circumferential direction (the direction indicated by the arrow S in FIG. 8A). Yes. In FIG. 8A, a plan view in which the belt layer 400 is developed is shown. In a state where the belt layer 400 is wound around the tire, the side surface 420A of the rubber-coated cord 420 shown at the bottom of FIG. 8A and the side surface 420B of the rubber-coated cord 420 shown at the top are bonded to each other. .

Further, each rubber-coated cord 420 is laid between both end portions 400EW of the belt layer 400 in the tire width direction. As shown in FIG. 8B, each rubber covered cord 420 is formed by covering a reinforcing cord 420C with a covering rubber 420S. For this reason, the end surface of the reinforcement cord 420C is exposed at the tire width direction end portion 400EW of the belt layer 400.

The reinforcement cord 420C is plated with cobalt on the outer peripheral surface in the same manner as the reinforcement cord 42C. The end surface of the reinforcing cord 42C is not plated, and the steel is exposed in a solid state. For this reason, the end surface of the reinforcing cord 42C is less likely to adhere to the tread rubber that covers the belt layer 400 as compared to the outer peripheral surface. For this reason, the belt layer 400 and the tread rubber covering the belt layer 400 are easily peeled off.

That is, the belt layer 40 in the tire 10 according to the present embodiment has a smaller number of locations that serve as a starting point for separation from the tread rubber 60G than the belt layer 400 in the comparative example.

Further, in the tire 10 according to the present embodiment, the inclination angle of the rubber-coated cord 42 with respect to the tire circumferential direction is 10 ° or less on the tire equatorial plane. For this reason, compared with the case where the inclination angle of the covering cord with respect to the tire circumferential direction is larger than 10 °, for example, the inclination angle of the covering cord becomes closer to the circumferential direction. As a result, the rubber-coated cord 42 exhibits a function as a gutter and can suppress out-of-plane deformation of the tread 60.

In the present embodiment, both end portions 42E1 and 42E2 of the rubber-coated cord 42 are disposed at different positions in the tire circumferential direction. For this reason, compared with the case where both end portions 42E1 and 42E2 of the rubber-coated cord 42 are arranged at the same position in the tire circumferential direction, the location that becomes the base point of separation from the tread rubber 60G in the tire circumferential direction can be dispersed.

In the present embodiment, the width direction end portion 50EW of the resin reinforcing layer 50 is disposed on the inner side in the tire width direction than the width direction end portion 40EW of the belt layer 40, but the embodiment of the present disclosure is not limited thereto. . For example, as shown in FIG. 5, the width direction end portion 50EW of the resin reinforcing layer 50 may be disposed outside the width direction end portion 40EW of the belt layer 40 in the tire width direction. In the present embodiment, the resin reinforcing layer 50 is formed of a thermoplastic resin. For this reason, the resin reinforcing layer 50 is formed in close contact with the width direction end portion 40EW of the belt layer 40 in the vulcanization step in forming the tire 10.

By doing in this way, the outer side in the tire radial direction of the belt layer 40 is covered with the resin reinforcing layer 50, so that the belt layer 40 is hardly deformed. That is, the resin reinforcing layer 50 suppresses the input of external force to the belt layer 40, and thus the deformation of the belt layer 40 is suppressed. In particular, since both end portions 42E1 and 42E2 of the rubber-coated cord 42 in the belt layer 40 are covered with the resin reinforcing layer 50, the both end portions 42E1 and 42E2 are the starting points of the separation between the belt layer 40, the resin reinforcing layer 50, and the tread rubber 60G. Can be suppressed.

In the present embodiment, the resin reinforcing layer 50 is disposed on the outer side in the tire radial direction of the belt layer 40, but the embodiment of the present disclosure is not limited thereto. For example, as shown in FIG. 6, the resin reinforcing layer 50 may be disposed on the inner side in the tire radial direction of the belt layer 40. In this case, it is preferable that the end portion 50EW in the width direction of the resin reinforcing layer 50 is disposed on the outer side in the tire width direction from the end portion 40EW in the width direction of the belt layer 40. By doing in this way, even if the belt layer 40 receives an external force and tries to deform inward in the tire radial direction, it is stiffened by the resin reinforcing layer 50 and the deformation is suppressed.

In the present embodiment, the belt layer 40 is formed by winding a substantially square rubber-coated cord 42 formed by coating one reinforcing cord 42C with a coating rubber 42S around the outer peripheral surface of the carcass 14, The embodiment of the present disclosure is not limited to this.

For example, as shown in FIG. 3B, a rubber-coated cord 44 having a substantially parallelogram cross section formed by coating a plurality of (for example, six) reinforcing cords 44C with a coating rubber 44S is formed on the outer peripheral surface of the carcass 14. It may be formed by winding.

Further, if the rubber-coated cord 42 is wound at least one turn around the carcass 14 (that is, if it is wound spirally), the number of the rubber-coated cord 42 is not limited to one, for example, two or more. It may be used.

As shown in FIG. 2, when the width of the belt layer 40 is (W1) and the circumferential length of the carcass 14 on the tire equatorial plane is (L1), the rubber-coated cord 42 is wound around the carcass 14 by one or more rounds. In order to rotate, as shown in FIG. 7A, the angle θ1 (see FIG. 4) of the rubber-coated cord 42 with respect to the tire circumferential direction may be set to (θ1 ≦ tan ⁻¹ (W1 / L1)).

Further, in order to form the belt layer 40 with one rubber-coated cord 42, when the width of the rubber-coated cord 42 is (W2), as shown in FIG. The angle θ1 (see FIG. 4) may be (θ1 ≦ tan ⁻¹ (W2 / L1)). Thus, the present disclosure can be implemented in various ways.

The entire disclosure of Japanese Patent Application No. 2018-093000 filed on May 14, 2018 is incorporated herein by reference. All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually described to be incorporated by reference, Incorporated herein by reference.

Claims

A pair of bead cores;
A carcass formed across the pair of bead cores;
On the outer side of the carcass in the tire radial direction, a belt layer formed by spirally winding a covering cord formed by covering the cord with rubber in the tire circumferential direction;
A resin reinforcing layer disposed on the outer side or the inner side in the tire radial direction of the belt layer; and
A tread provided on the outer side in the tire radial direction of the belt layer and the resin reinforcing layer;
Pneumatic tire with
The pneumatic tire according to claim 1, wherein an inclination angle of the covering cord with respect to a tire circumferential direction is 10 ° or less on a tire equator plane.
The pneumatic tire according to claim 1 or 2, wherein an end portion in the tire width direction of the resin reinforcing layer is disposed on an outer side in the tire width direction from an end portion in the tire width direction of the belt layer.