JP2022088821A - Run-flat tire - Google Patents

Abstract

To provide a run-flat tire capable of not only reducing rolling resistance by reduction of its weight but also having a run-flat function.SOLUTION: A run-flat tire comprises: a pair of beads 10; a pair of side walls 20 extending from the pair of beads 10 to the outside in a tire radial direction respectively; a tread 30 arranged between the pair of side walls 20; a carcass ply 40 bridged between the pair of beads 10; and a reinforcement rubber layer 60, in the side walls 20, arranged on a tire inner cavity side of the carcass ply 40. A metal fiber layer 70 including a metal cord 71 as a metal reinforcement material is arranged inside the reinforcement rubber layer 60.SELECTED DRAWING: Figure 1

Description

The present invention relates to a run-flat tire.

Conventionally, a side-reinforcing type run-flat tire in which a reinforcing rubber layer is arranged on a sidewall is known. In such a run-flat tire, when the internal pressure of the tire decreases, the reinforcing rubber layer suppresses the tire from being completely flattened, and the run-flat running for a certain distance (running in a state where the internal pressure of the tire decreases). ) Is possible.
For example, Patent Document 1 discloses a run-flat tire that improves durability during run-flat running by defining a rubber composition and a composition ratio of a side reinforcing rubber portion corresponding to the reinforcing rubber layer. There is.

Japanese Unexamined Patent Publication No. 2016-35011

The reinforcing rubber layer that reinforces the side of the tire enables run-flat running, but may increase the weight of the tire and cause an increase in rolling resistance. Therefore, there is a demand for a reinforcing structure that ensures a run-flat function while being lightweight.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a run-flat tire capable of achieving both a reduction in rolling resistance due to weight reduction and a run-flat function.

The run-flat tire of the present invention has a pair of beads, a pair of sidewalls extending outward in the tire radial direction from each of the pair of beads, a tread arranged between the pair of sidewalls, and a space between the pair of beads. A carcass ply bridged over the tire, and a reinforcing rubber layer arranged on the tire cavity side of the carcass ply on the sidewall, and the inside of the reinforcing rubber layer is reinforced including a metal reinforcing material. The parts are arranged.

According to the present invention, it is possible to provide a run-flat tire in which a side reinforcing function is ensured while being lightened, and both reduction of rolling resistance and improvement of run-flat durability can be achieved.

It is a figure which shows the half cross section in the tire width direction of the run flat tire which concerns on embodiment of this invention. It is a partially enlarged view of FIG. It is a partial side view of the run-flat tire of an embodiment. It is a half sectional view at the time of the run-flat running of the run-flat tire of an embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a half cross section of a tire 1 which is a run-flat tire according to the present embodiment in the tire width direction. FIG. 2 is an enlarged view of a part of FIG.

Since the basic structure of the tire 1 is symmetrical in the cross section in the tire width direction, the cross section of the right half is shown in FIG. 1. In FIG. 1, reference numeral S1 is a tire equatorial plane. The tire equatorial plane S1 is a plane orthogonal to the tire rotation axis (tire meridian) and is a plane located at the center in the tire width direction.

The cross-sectional view of FIG. 1 is a tire width direction cross-sectional view (tire meridian cross-sectional view) in a no-load state in which a tire is mounted on a specified rim and filled with a specified internal pressure. The specified rim refers to the standard rim specified by JATTA according to the tire size. The specified internal pressure is, for example, 180 kPa when the tire is for a passenger car.

Here, the tire width direction is a direction parallel to the tire rotation axis, and is a paper surface left-right direction in the cross-sectional view of FIG. In FIG. 1, it is shown as the tire width direction X.
The inner side in the tire width direction is the direction approaching the tire equatorial plane S1, and is the left side of the paper in FIG. The outside in the tire width direction is the direction away from the tire equatorial plane S1, and is the right side of the paper in FIG.
Further, the tire radial direction is a direction perpendicular to the tire rotation axis, and is a vertical direction on the paper surface in FIG. In FIG. 1, it is shown as the tire radial direction Y.
The tire radial outer side is a direction away from the tire rotation axis, and in FIG. 1, it is the upper side of the paper surface. The inner side in the tire radial direction is a direction approaching the tire rotation axis, and in FIG. 1, it is the lower side of the paper surface.
The same applies to FIG.

The tire 1 is, for example, a run-flat tire for a passenger car. As shown in FIG. 1, the tire 1 includes a pair of beads 10 provided on both sides in the tire width direction, a pair of sidewalls 20 extending outward in the tire radial direction from each of the pair of beads 10, and a pair of sidewalls. It includes a tread 30 arranged between 20 and a carcass ply 40 arranged between a pair of beads 10 and an inner liner 50 arranged on the tire lumen side of the carcass ply 40.

The bead 10 has a bead core 11, a bead filler 12 extending outward in the tire radial direction of the bead core 11, a chainer 13, and a rim protector 15.

The bead core 11 is an annular member formed by winding a metal bead wire coated with rubber a plurality of times, and is a member that serves to fix the air-filled tire 1 to the rim.
The bead filler 12 is a rubber member having a tapered shape as it extends outward in the tire radial direction. The bead filler 12 is a member provided for increasing the rigidity of the peripheral portion of the bead 10 and ensuring high maneuverability and stability. The bead filler 12 is made of rubber having a hardness higher than that of the surrounding rubber member, for example.

The checker 13 is provided inside the carcass ply 40 provided around the bead core 11 in the tire radial direction.
The rim protector 15 includes a rim strip rubber 14. The rim strip rubber 14 is arranged outside the chaher 13 and the carcass ply 40 in the tire width direction. A top portion 14a along the tire circumferential direction is formed on the outer surface of the rim strip rubber 14. The rim strip rubber 14 comes into contact with the rim on which the tire 1 is mounted. The rim protector 15 is continuous in an annular shape in the tire circumferential direction. The rim protector 15 has a function of protecting the rim (not shown) from trauma.

The sidewall 20 includes a sidewall rubber 21 arranged on the outer side of the carcass ply 40 in the tire width direction, and a reinforcing rubber layer 60.
The sidewall rubber 21 constitutes the outer wall surface of the tire 1. The sidewall rubber 21 is a portion that bends most when the tire 1 acts as a cushion, and a flexible rubber having fatigue resistance is usually adopted.
The reinforcing rubber layer 60 will be described later.

The tread 30 includes an endless belt 31, a cap ply 32, and a tread rubber 33.

The belt 31 is arranged outside the carcass ply 40 in the tire radial direction. The cap ply 32 is arranged outside the tire radial direction of the belt 31.
The belt 31 is a member that reinforces the tread 30. The belt 31 of the present embodiment has a two-layer structure including an inner belt 311 and an outer belt 312. Both the inner belt 311 and the outer belt 312 have a structure in which a plurality of cords such as steel cords are covered with rubber.

In the two-layer structure belt 31 of the present embodiment, the inner belt 311 is wider than the outer belt 312, so that the outer end 31A of the belt 31 in the tire width direction is the outer end of the inner belt 311 in the tire width direction. It is composed. By providing the belt 31, the rigidity of the tire 1 is ensured, and the ground contact property of the tread 30 with respect to the road surface is improved.
The belt 31 is not limited to the two-layer structure, and may have a one-layer structure or a three-layer or more structure.

The cap ply 32 is a member that reinforces the tread 30 together with the belt 31. The cap ply 32 has a structure in which a plurality of insulating organic fiber cords such as polyamide fibers are covered with rubber.
In the present embodiment, the outer end 32A in the tire width direction of the cap ply 32 extends outward in the tire width direction from the outer end 31A in the tire width direction of the belt 31. By providing the cap ply 32, it is possible to improve the durability and reduce the road noise during traveling.

An endless rubber pad 35 is arranged between both ends of the inner belt 311 and the outer belt 312 on the outer side in the tire width direction and both ends of the cap ply 32 on the outer side in the tire width direction.

The tread rubber 33 is arranged on the outer side of the cap ply 32 in the tire radial direction. The tread rubber 33 is a member constituting a ground contact surface 331 that comes into contact with the road surface during traveling. The ground plane 331 of the tread rubber 33 is provided with, for example, a tread pattern 34 composed of a plurality of grooves. The tread pattern 34 has a plurality of main grooves 341 arranged in the tire width direction. Each of the plurality of main grooves 341 extends along the tire circumferential direction.

The carcass ply 40 constitutes a ply that is the skeleton of the tire 1. The carcass ply 40 is embedded in the tire 1 so as to pass between the pair of beads 10 and the pair of sidewalls 20 and the tread 30.
The carcass ply 40 includes a plurality of carcass cords that form the skeleton of the tire 1. The plurality of carcass cords extend in the tire width direction, for example, and are arranged side by side in the tire circumferential direction. The carcass cord is composed of an insulating organic fiber cord such as polyester or polyamide. A plurality of carcass cords are covered with rubber to form a carcass ply 40.

The carcass ply 40 has a ply body 401 extending from one bead core 11 to the other bead core 11 and extending between the tread 30 and the bead 10, and a pair of bent portions 402 folded back from the ply body 401 by the bead core 11. And a pair of folded portions 403 extending outward in the tire radial direction from each of the bent portions 402. The ply main body portion 401, the bent portion 402, and the folded portion 403 are continuous.

The ply main body 401 is arranged inside the bead core 11 and the bead filler 12 in the tire width direction inside the tire radial direction. The folded-back portion 403 is arranged on the inner side in the tire radial direction and on the outer side in the tire width direction of the bead core 11 and the bead filler 12. In the portions other than the bead core 11 and the bead filler 12, the folded-back portion 403 is overlapped with the ply main body portion 401. The bent portion 402 constitutes the innermost portion in the tire radial direction in the carcass ply 40.

The carcass ply 40 of the present embodiment is composed of two layers of carcass plies in which the first carcass ply 410 and the second carcass ply 420 are stacked, but the carcass ply 40 may be one layer. It may have three or more layers.

As in the present embodiment, it is preferable that the carcass ply 40 composed of at least two or more plies is sandwiched between the bead filler 12 and the reinforcing rubber layer 60 described later. As a result, it is possible to more effectively suppress the occurrence of local deformation in the vicinity of the rim mounting portion, and further improve the run-flat durability.

The chaher 13 of the bead 10 described above is provided so as to surround the end portion of the carcass ply 40 including the bent portion 402 on the inner side in the tire radial direction. Further, the rim strip rubber 14 is arranged outside the folded portion 403 of the chaher 13 and the carcass ply 40 in the tire width direction. The tire radial outer end of the rim strip rubber 14 is covered with the sidewall rubber 21 described above.

The inner liner 50 covers the inner surface of the tire between the pair of beads 10 and constitutes the inner wall surface of the tire 1. In the tread 30, the inner liner 50 covers the inner surface of the ply main body portion 401 of the carcass ply 40, and in the region extending from the tread 30 to the pair of sidewalls 20, covers the inner surface of the reinforcing rubber layer 60, and is paired with the pair of sidewalls 20. In the region extending over the bead 10, the inner surface of the reinforcing rubber layer 60 and the chaher 13 is covered.
The inner liner 50 is made of air-permeable rubber to prevent air in the tire lumen from leaking to the outside.

The reinforcing rubber layer 60 constituting the sidewall 20 is arranged so as to be sandwiched between the carcass ply 40 and the inner liner 50.

The reinforcing rubber layer 60 is a side reinforcing rubber having a substantially crescent shape in a cross-sectional view in the tire width direction (cross-sectional view of the tire meridian). The reinforcing rubber layer 60 is provided in an annular shape over the entire circumference of the tire 1. The reinforcing rubber layer 60 has a function of preventing the tire 1 from being completely flattened even when the internal pressure of the tire 1 is reduced.

Here, as shown in FIG. 1, on the tire outer surface side of the carcass ply 40 in the transition region between the tread 30 and the sidewall 20, the sidewall rubber 21 extends toward the tread 30, and the tread rubber 33 is on the side. The tread rubber 33 extends toward the wall 20 and covers the outer surface side of the sidewall rubber 21.

Further, on the tire outer surface side of the carcass ply 40 in the transition region between the bead 10 and the sidewall 20, the sidewall rubber 21 extends toward the bead 10, and the rim strip rubber 14 extends toward the sidewall 20. , The sidewall rubber 21 covers the outer surface side of the rim strip rubber 14.

Further, on the tire lumen side of the carcass ply 40 of the bead 10, the tire radial inner end 60B of the reinforcing rubber layer 60 is covered by the tire radial outer end of the chaher 13.
The inner liner 50 further covers the tire lumen side of these rubber members.

Here, as the rubber used for the bead filler 12 and the reinforcing rubber layer 60, at least rubber having a hardness higher than that of the sidewall rubber 21 and the inner liner 50 is used.
The hardness of the rubber is a value (durometer hardness) measured by a type A durometer in a 23 ° C atmosphere in accordance with JIS K6253.

For example, when the hardness of the sidewall rubber 21 is used as a reference, it is more preferable to use a rubber having a hardness of about 1.2 to 2.3 times the hardness of the sidewall rubber 21 as the hardness of the bead filler 12. Further, it is more preferable to use a rubber having a hardness of about 1.1 times to 1.9 times the hardness of the sidewall rubber 21 for the hardness of the reinforcing rubber layer 60.
Further, it is more preferable to use a rubber having a hardness of about 1 to 1.6 times the hardness of the sidewall rubber 21 for the hardness of the rim strip rubber 14.
By setting such hardness, it is possible to maintain a balance between flexibility as a tire and rigidity in the vicinity of the bead 10, and to secure run-flat durability.

In the tire 1 of the present embodiment, the metal fiber layer 70 as a reinforcing portion is embedded and arranged inside the reinforcing rubber layer 60. As a result, the rigidity of the reinforcing rubber layer 60 can be effectively improved, the compression strain of the tire is sufficiently suppressed even during run-flat running, and excellent run-flat durability is realized.

As shown in FIG. 1, the metal fiber layer 70 is a strip-shaped layer having a curved shape substantially along the cross-sectional shape of the reinforcing rubber layer 60 in a cross-sectional view in the tire width direction. The metal fiber layer 70 is provided in an annular shape over the entire circumference of the tire 1. The metal fiber layer 70 has a bending direction length of, for example, about 50 to 70% of the bending direction length of the reinforcing rubber layer 60 in a cross-sectional view in the tire width direction, and the tire diameter inside the reinforcing rubber layer 60. It is located closer to the inside of the direction. The metal fiber layer 70 is arranged inside the reinforcing rubber layer 60 at substantially the center of the thickness of the reinforcing rubber layer 60.

As shown in FIG. 3, the metal fiber layer 70 of the present embodiment is configured to include a plurality of metal cords 71 as reinforcing materials and a rubber 72 that covers and integrates the plurality of metal cords 71. .. FIG. 3 is a virtual view of the metal fiber layer 70 embedded inside the reinforcing rubber layer 60 of the tire 1 when viewed from the outside in the tire width direction toward the inside in the tire width direction, that is, when viewed from the side. Is.

As shown in FIG. 3, the plurality of metal cords 71 extend at an angle with respect to the tire radial direction Y, and are arranged at intervals in the tire circumferential direction C in the inclined state. The angle θ formed by the radial direction Y of the tire 1 and the extending direction of the metal cord 71 is preferably, for example, 10 ° or more and 40 ° or less. Since the plurality of metal cords 71 extend at an angle with respect to the tire radial direction and are arranged at intervals in the tire circumferential direction in the inclined state, the interval between the plurality of metal cords 71 arranged in the tire circumferential direction is large. , It is a mode that spreads toward the outside in the radial direction of the tire.

As the metal constituting the metal cord 71, a metal cord material having high strength, flexibility, and high fatigue resistance is preferable, and for example, a steel cord is more preferably used. In the case of steel cords, for example, several to dozens of strands made of high carbon steel with a diameter of 0.1 to φ0.5 mm are twisted together, and if necessary, plating is applied to improve the adhesiveness with rubber. Things are used. The metal cord 71 of the present embodiment preferably has an outer diameter (cord diameter) of 0.5 to 1.2 mm or less.

In the present embodiment, the carcass cords constituting the carcass ply 40 are arranged radially (in the radial direction) from the center of the tire 1, and the tire diameter is arranged in the sidewall 20 in which the reinforcing rubber layer 60 is arranged. It extends in the direction. Therefore, in the present embodiment, the angle between the extending direction of the carcass cord of the carcass ply 40 and the extending direction of the metal cord 71 of the metal fiber layer 70 is 10 ° or more and 40 ° or less. In this way, by making the carcass cord of the carcass ply 40 and the metal cord 71 of the metal fiber layer 70 different in extending direction with respect to the radial direction, the rigidity of the portion where the carcass ply 40 and the metal fiber layer 70 overlap can be increased. can.

For example, in the middle of the manufacturing process of the reinforcing rubber layer 60, a divided body of the reinforcing rubber layer 60 in a raw rubber state divided into two in the thickness direction is prepared, a metal fiber layer 70 is sandwiched between the divided bodies, and then vulcanization is performed. By processing the reinforcing rubber layer 60 by performing treatment or the like, the reinforcing rubber layer 60 in which the metal fiber layer 70 is embedded can be obtained.

According to FIG. 2, as described above, the metal fiber layer 70 has a bending direction length of, for example, about 50 to 70% of the bending direction length of the reinforcing rubber layer 60 in a cross-sectional view in the tire width direction, and is reinforced. Inside the rubber layer 60, it is arranged closer to the inner side in the tire radial direction. A preferred embodiment of the positional relationship between the reinforcing rubber layer 60 and the metal fiber layer 70 arranged inside the tire 1 in the present embodiment is as follows.

The distance L1 from the tire radial outer end 60A of the reinforcing rubber layer 60 to the tire radial outer end 70A of the metal fiber layer 70 is preferably 10 mm or more. The distance L1 referred to here is the shortest distance from the tire radial outer end 60A of the reinforcing rubber layer 60 to the tire radial outer end 70A of the metal fiber layer 70.
The distance L2 from the tire radial inner end 60B of the reinforcing rubber layer 60 to the tire radial inner end 70B of the metal fiber layer 70 is preferably 10 mm or more. The distance L2 referred to here is the shortest distance from the tire radial inner end 60B of the reinforcing rubber layer 60 to the tire radial inner end 70B of the metal fiber layer 70.

The tire radial outer end 70A of the metal fiber layer 70 is located outside the tire radial position with respect to the tire maximum width position 1A. The tire radial distance L3 from the tire radial outer end 70A of the metal fiber layer 70 to the tire maximum width position 1A is preferably 20 mm or more.
The tire radial inner end 70B of the metal fiber layer 70 is located inside the tire radial position with respect to the tire maximum width position 1A. The tire radial distance from the tire radial inner end 70B of the metal fiber layer 70 to the tire maximum width position 1A is preferably 20 mm or more.

The tire radial inner end 70B of the metal fiber layer 70 is located inside the tire radial outer end 12A of the bead filler 12. The tire radial distance L5 from the tire radial inner end 70B of the metal fiber layer 70 to the tire radial outer end 12A of the bead filler 12 is preferably 10 mm or more.

According to the tire 1 of the present embodiment, the following effects are obtained.

(1) The tire 1 according to the present embodiment has a pair of beads 10, a pair of sidewalls 20 extending outward in the tire radial direction from each of the pair of beads 10, and a tread 30 arranged between the pair of sidewalls 20. A carcass ply 40 bridged between the pair of beads 10 and a reinforcing rubber layer 60 arranged on the tire cavity side of the carcass ply 40 on the sidewall 20 are provided inside the reinforcing rubber layer 60. , A metal fiber layer 70 including a metal cord 71 as a metal reinforcing material is arranged.

Since the metal cord 71 as a metal reinforcing material is included, the reinforcing rubber layer 60 can be made thinner as long as it has the same reinforcing function as the sidewall 20 as compared with the case where the reinforcing material is only rubber. Therefore, the side reinforcement function is secured while being reduced in weight. Rolling resistance is reduced as the weight is reduced. That is, according to the present embodiment, the side reinforcement function is secured while the weight is reduced, and both reduction of rolling resistance and improvement of run-flat durability can be achieved.

FIG. 4 shows a deformation state of the tire 1 during run-flat running in which the internal pressure of the tire 1 of the vehicle traveling on the road surface H becomes almost zero. In FIG. 4, the road surface H side, that is, the lower side of the paper surface is the outer side in the tire radial direction. During the run-flat running, the reinforcing rubber layer 60 reinforced by the metal fiber layer 70 suppresses the compression strain of the sidewall 20, which enables the run-flat running.

(2) In the tire 1 according to the present embodiment, the metal fiber layer 70 includes a plurality of metal cords 71 and a rubber 72 that covers the plurality of metal cords 71.

As a result, the reinforcing portion of the reinforcing rubber layer 60 can be made thin, so that the reinforcing rubber layer 60 itself can be made thin, and the rolling resistance associated with the weight reduction can be reduced more effectively.

(3) In the tire 1 according to the present embodiment, the plurality of metal cords 71 are arranged so as to be inclined and extend in the tire radial direction in the side view of the tire.

As a result, the resistance force, that is, the rigidity of the metal fiber layer 70 to the flattening (buckling) of the tire 1 is increased during the run-flat running. Therefore, it is possible to sufficiently suppress the compression distortion of the tire 1 and improve the run-flat durability.

(4) In the tire 1 according to the present embodiment, the metal fiber layer 70 is arranged substantially at the center of the thickness of the reinforcing rubber layer 60.

As a result, even if the metal fiber layer 70 is deformed, the metal fiber layer 70 is less likely to be exposed from the reinforcing rubber layer 60, and the function of the metal fiber layer 70 that reinforces the reinforcing rubber layer 60 is maintained.

(5) The tire 1 according to the present embodiment includes a mode in which the distance from the tire radial outer end 60A of the reinforcing rubber layer 60 to the tire radial outer end 70A of the metal fiber layer 70 is 10 mm or more.

As a result, a sufficient distance from the tire radial outer end 60A of the reinforcing rubber layer 60 to the tire radial outer end 70A of the metal fiber layer 70 is sufficiently secured, and the tire radial outer end 70A of the metal fiber layer 70 is thinned. It is possible to suppress exposure of the reinforcing rubber layer 60 in the vicinity of the tire radial outer end 60A.

(6) The tire 1 according to the present embodiment includes a mode in which the distance from the tire radial inner end 60B of the reinforcing rubber layer 60 to the tire radial inner end 70B of the metal fiber layer 70 is 10 mm or more.

As a result, a sufficient distance from the tire radial inner end 60B of the reinforcing rubber layer 60 to the tire radial inner end 70B of the metal fiber layer 70 is sufficiently secured, and the tire radial inner end 70B of the metal fiber layer 70 is thinned. Exposure of the reinforcing rubber layer 60 near the inner end 60B in the tire radial direction is suppressed.

(7) In the tire 1 according to the present embodiment, the tire radial outer end 70A of the metal fiber layer 70 is located outside the tire radial position from the tire maximum width position 1A, and the metal fiber layer 70 is located in the tire radial direction. It includes a form in which the tire radial distance from the outer end 70A to the tire maximum width position 1A is 20 mm or more.

As a result, the metal fiber layer 70 sufficiently covers the vicinity of the tire maximum width position 1A, which is the region where the compression strain is most generated, so that the compression strain of the tire 1 is sufficiently suppressed during normal running and run-flat running.

(8) In the tire 1 according to the present embodiment, the tire radial inner end 70B of the metal fiber layer 70 is located inside the tire radial position with respect to the tire maximum width position 1A, and the metal fiber layer 70 is located in the tire radial direction. It includes a form in which the tire radial distance from the inner end 70B to the tire maximum width position 1A is 20 mm or more.

As a result, the metal fiber layer 70 sufficiently covers the vicinity of the tire maximum width position 1A, which is the region where the compression strain is most generated during normal running, so that the compression strain of the tire 1 is sufficiently suppressed during normal running and run-flat running. Will be done.

When the tire radial outer end 70A or the tire radial inner end 60B of the metal fiber layer 70 is located at the same level as the tire maximum width position 1A, the tire radial outer end 70A or the tire radial inner end 60B becomes the starting point. There is a risk that stress will be concentrated and compressive strain will increase. However, as in the present embodiment, the tire radial outer end 70A of the metal fiber layer 70 is arranged at a position 20 mm or more outside the tire radial position from the tire maximum width position 1A, and the tire radial inner end of the metal fiber layer 70 is arranged. By arranging the 70B at a position of 20 mm or more inside the tire maximum width position 1A in the tire radial direction, the reinforcing effect of the metal fiber layer 70 is sufficiently exhibited, and the compression strain of the tire 1 is sufficiently suppressed.

(9) In the tire 1 according to the present embodiment, the bead 10 includes a bead core 11 and a bead filler 12 extending outward in the tire radial direction of the bead core 11, and the inner end in the tire radial direction of the metal fiber layer 70. 70B is located inside the tire radial outer end 12A of the bead filler 12 in the tire radial direction, and is a tire from the tire radial inner end 70B of the metal fiber layer 70 to the tire radial outer end 12A of the bead filler 12. Includes a form in which the radial distance is 10 mm or more.

As a result, the end portion of the metal fiber layer 70 on the inner side in the tire radial direction overlaps with the bead filler 12, so that the rigidity of the bead 10 is improved.

The tire of the present invention can be used as various tires for passenger cars, light trucks, trucks, buses and the like.

The present invention is not limited to the above embodiment, and is included in the scope of the present invention even if it is modified or improved to the extent that the object of the present invention can be achieved.
For example, in the metal fiber layer 70 of the above embodiment, a plurality of metal cords 71 are adopted as the metal reinforcing material, but the reinforcing material may be a metal member and can exert a reinforcing effect. However, the mode is not limited.
The structure of the reinforcing portion of the present invention is not limited as long as it includes a reinforcing material made of metal, and the reinforcing material may be a single body or a combination of the reinforcing material and other materials. ..

1 tire (run flat tire)
1A Tire maximum width position 10 Bead 11 Bead core 12 Bead filler 20 Side wall 30 Tread 40 Carcasply 60 Reinforcing rubber layer 60A Tire radial outer end of reinforcing rubber layer 60B Tire radial inner end of reinforcing rubber layer 70 Metal fiber layer (reinforcement) Department)
70A Tire radial outer end of metal fiber layer 70B Tire radial inner end of metal fiber layer 71 Metal cord (reinforcing material)

Claims (9)

A pair of beads and
A pair of sidewalls extending outward in the tire radial direction from each of the pair of beads,
The tread placed between the pair of sidewalls and
The carcass ply spanned between the pair of beads,
The sidewall is provided with a reinforcing rubber layer disposed on the tire lumen side of the carcass ply.
A run-flat tire in which a reinforcing portion including a metal reinforcing material is arranged inside the reinforcing rubber layer. The run-flat tire according to claim 1, wherein the reinforcing portion is composed of a metal fiber layer including a plurality of metal cords as the reinforcing material and rubber covering the plurality of metal cords. The run-flat tire according to claim 1 or 2, wherein the plurality of metal cords are arranged so as to be inclined and extend in the tire radial direction in a tire side view. The run-flat tire according to any one of claims 1 to 3, wherein the reinforcing portion is arranged substantially at the center of the thickness of the reinforcing rubber layer. The run-flat tire according to any one of claims 1 to 4, wherein the distance from the tire radial outer end of the reinforcing rubber layer to the tire radial outer end of the reinforcing portion is 10 mm or more. The run-flat tire according to any one of claims 1 to 5, wherein the distance from the tire radial inner end of the reinforcing rubber layer to the tire radial inner end of the reinforcing portion is 10 mm or more. The tire radial outer end of the reinforcing portion is located on the tire radial outer side of the tire maximum width position.
The run-flat tire according to any one of claims 1 to 6, wherein the tire radial distance from the tire radial outer end of the reinforcing portion to the tire maximum width position is 20 mm or more. The tire radial inner end of the reinforcing portion is located inside the tire radial direction with respect to the tire maximum width position.
The run-flat tire according to any one of claims 1 to 7, wherein the tire radial distance from the tire radial inner end of the reinforcing portion to the tire maximum width position is 20 mm or more. The bead comprises a bead core and a bead filler extending outward in the tire radial direction of the bead core.
The tire radial inner end of the reinforcing portion is located on the tire radial inner side of the tire radial outer end of the bead filler.
The run-flat tire according to any one of claims 1 to 8, wherein the tire radial distance from the tire radial inner end of the reinforcing portion to the tire radial outer end of the bead filler is 10 mm or more.

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