JP2000043517A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic radial tire to remarkably improve maneuvering stability without substantially lowering durability. SOLUTION: Carcass layers 2 and 3 being two layers of inner and outer layers are mounted between a pair of right and left bead parts 1 and 1. The two end parts of the inner carcass layer 2 are rolled up from the inside to the outside around a bead core 4, a bead filler 5 is wrapped with a turn up part 2a, and the two end parts of the outer carcass layer 3 are arranged at the outside of the turn up part 2a. In a so formed pneumatic radial tire, an inner reinforcing layer 9 formed of an organic fiber cord formed of a plurality of organic fiber cords is arranged between the inner carcass layer 2, the bead core 4, and the bead filler 5 in a state to be rolled up around the bead core 4. An outer reinforcing layer 10 formed of a plurality of steel cords is arranged between the turn up part 2a and the outer carcass layer 3. The wind-up height (CTU) of the turn up part 2a, the upper end height (RU1) of the inner reinforcing layer 9, the upper end height (RU2) of the outer reinforcing layer 10 are set to a relation of CTU>RU1>RU2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire in which a reinforcing layer is inserted from a bead portion to a side portion, and more specifically, to greatly improve steering stability without substantially reducing durability. The present invention relates to a pneumatic radial tire that has made it possible.

[0002]

2. Description of the Related Art Conventionally, in a tire for high-speed running, a reinforcement made of steel cord or organic fiber cord is used for a bead portion in order to improve the steering stability by suppressing deformation from a tire side portion to a bead portion during high-speed running. Inserting layers has been done. However, if a reinforcing layer made of steel cord is used to obtain a greater reinforcing effect, and the width of the reinforcing layer is too wide, the rigidity change at the side part will increase, and stress concentration will occur, resulting in durability. However, there was a problem that was reduced.

[0003] On the other hand, in Japanese Patent Application Laid-Open No. 6-143947, in a pneumatic tire having two carcass layers, two steel cord reinforcing layers are arranged outside the bead filler, and the positional relationship between them is determined. By specifying this, it is trying to achieve both steering stability and durability. However, in the case of a flat tire having a small sectional height, the edges of the two steel cord reinforcing layers are adjacent to each other, and this promotes stress concentration, so that the durability is insufficient.

In addition, when a reinforcing layer made of an organic fiber cord is inserted into a bead portion, the problem of durability due to stress concentration can be avoided, but the effect of improving steering stability is insufficient due to insufficient reinforcing effect. It will be enough.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic radial tire for a flat tire for high-speed running, which can substantially improve the steering stability without substantially lowering the durability. Is to provide.

[0006]

According to the present invention, there is provided a pneumatic radial tire according to the present invention, wherein two inner and outer carcass layers are mounted between a pair of left and right bead portions, and the inner carcass layer has a width in the tire width direction. Both ends are wound up from the inside of the tire to the outside around the bead core, and the turn-up portion wraps the bead filler arranged on the outer peripheral side of the bead core, and the both ends in the tire width direction of the outer carcass layer are respectively formed in the turn-up portion. In the pneumatic radial tire arranged on the outside, an inner reinforcing layer composed of a plurality of organic fiber cords is arranged between the inner carcass layer and the bead core and the bead filler so as to be wound around the bead core from the tire inside to the outside. Along with
An outer reinforcing layer made of a plurality of steel cords is disposed between the turnup portion and the outer carcass layer, and a winding height (CTU) of the turnup portion and an upper end height (RU1) of the inner reinforcing layer. , Wherein the upper end height (RU2) of the outer reinforcing layer has a relationship of CTU>RU1> RU2.

As described above, the outer reinforcing layer is made of a steel cord, and the inner reinforcing layer is made of an organic fiber cord, and the positional relationship between the edges is specified as described above. The reinforcing effect can be obtained. Therefore, in the flat tire for high-speed running, the steering stability can be significantly improved without impairing the durability.

In the present invention, in order to avoid stress concentration more effectively, the upper end height (BF) of the bead filler is set.
T), the lower end height (RL1) of the inner reinforcing layer and the lower end height (RL2) of the outer reinforcing layer are expressed as CTU>RU1> RU.
It is preferable that the relationship of 2>BFT>RL1> RL2 be satisfied. It is preferable that the distance between the upper end of the inner reinforcing layer and the upper end of the outer reinforcing layer is 4 to 10 mm.

The winding height (CTU) of the turn-up portion, the upper end height of the inner reinforcing layer (RU1), the upper end height of the outer reinforcing layer (RU2), the upper end height of the bead filler (BFT), the inner side Both the lower end height (RL1) of the reinforcing layer and the lower end height (RL2) of the outer reinforcing layer are measured in the tire radial direction from the bead base position. The present invention is preferably applied to a tire having a tire section height of 100 mm or less, or a tire having an aspect ratio of 55% or less. By applying the present invention to such a flat tire, remarkable effects can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 illustrates a pneumatic radial tire according to an embodiment of the present invention. In the drawing, two inner and outer carcass layers 2, 3 in which a plurality of reinforcing cords are arranged in a radial direction are mounted between a pair of left and right bead portions 1, 1. The inner carcass layer 2 has both ends in the tire width direction wound around the bead core 4 from the inside to the outside of the tire to form a turn-up portion 2a, and the turn-up portion 2a is used to form a hard rubber disposed on the outer peripheral side of the bead core 4. Bead filler 5 is wrapped. On the other hand, both ends of the outer carcass layer 3 in the tire width direction are disposed below the bead core 4 through the outside of the turn-up portion 2a. That is,
The tire has a so-called 1-1 high-turn-up structure.

On the outer peripheral side of the carcass layers 2 and 3 in the tread portion 6, there are provided two belt layers 7 and 7 each having a plurality of reinforcing cords covered with coat rubber. These belt layers 7, 7 are arranged such that the reinforcing cords are inclined with respect to the tire circumferential direction, and the reinforcing cords intersect each other between the layers. A plurality of reinforcing cords are arranged substantially parallel to the tire circumferential direction on the outer peripheral side of the belt layers 7, 7 in order to prevent the belt layers 7, 7 from rising due to centrifugal force during high-speed running. A belt cover layer 8 is provided so as to cover the belt layers 7.

In the pneumatic tire, an inner reinforcing layer 9 in which a plurality of organic fiber cords are coated with a coating rubber is disposed between the inner carcass layer 2 and the bead core 4 and the bead filler 5. More specifically, the inner reinforcing layer 9 extends from the inner surface side of the bead filler 5 to the outer surface side of the bead filler 5 through the radial inside of the bead core 4. It is preferable to use aromatic polyamide fiber (Kevlar), nylon fiber, rayon fiber or the like as an organic fiber cord constituting the inner reinforcing layer 9. Also,
The inclination angle of the organic fiber cord in the inner reinforcing layer 9 with respect to the tire circumferential direction may be set in a range of 45 ° ± 15 °. By setting the inclination angle of the organic fiber cord within the above range, it is possible to simultaneously satisfy the reinforcing effect and the durability.

On the other hand, between the turnup portion 2a of the inner carcass layer 2 and the outer carcass layer 3, an outer reinforcing layer 10 in which a plurality of steel cords are covered with coat rubber is disposed. In the outer reinforcing layer 10, the inclination angle of the steel cord with respect to the tire circumferential direction may be set in a range of 20 ° ± 10 °. By setting the inclination angle of the steel cord within the above range, it is possible to simultaneously satisfy the reinforcing effect and the durability.

In inserting the inner reinforcing layer 9 and the outer reinforcing layer 10, the winding height (CTU) of the turn-up portion 2 a, the upper end height of the inner reinforcing layer 9 (RU 1), and the upper end height of the outer reinforcing layer 10. (RU2), the upper end height of the bead filler 5 (BFT), the lower end height of the inner reinforcing layer 9 (RL
1) Regarding the lower end height (RL2) of the outer reinforcing layer 10,
The relationship of CTU>RU1> RU2 is satisfied, and more preferably, CTU>RU1>RU2>BFT> RL
1> RL2 is set so as to satisfy the relationship. In the above relational expression, the distance between the edges is preferably 4 mm or more and 10 mm or less, and particularly, the distance between the upper end of the inner reinforcing layer 9 and the upper end of the outer reinforcing layer 10 is 4 mm.
It is preferable that it is not less than 10 mm. By setting the edge of each part to the above positional relationship, it is possible to effectively disperse the stress generated in the tire during running.

In the tire provided with the two carcass layers as described above, these carcass layers have a 1-1 high turn-up structure, and two reinforcing layers are used. By arranging them inside and outside the vehicle, a decrease in durability can be suppressed to some extent while improving the steering stability. However, when the two reinforcing layers are simply inserted outside the bead filler 5,
The edges (upper ends or lower ends) of the two reinforcing layers are arranged close to each other outside the bead filler 5, which causes a decrease in durability. In addition, if an attempt is made to secure the edge interval of the reinforcing layer, the edge will be disposed near the height of the rim flange, and the durability will be reduced.

Therefore, in the present invention, the inner reinforcing layer 9 on the bead filler side is arranged so as to be wound up around the bead core 4 from the inside to the outside of the tire, thereby dispersing the edge. However, if the inner reinforcing layer 9 is made of a steel cord, a change in rigidity inside the bead is increased, and durability is reduced due to stress concentration. Therefore, the inner reinforcing layer 9 needs to be made of an organic fiber cord. . The use of the organic fiber cord for the inner reinforcing layer 9 not only avoids stress concentration inside the bead but also prevents deterioration of the formability when the inner reinforcing layer 9 is rolled up together with the carcass layer 2. Can be.

Further, regarding the arrangement of the edges near the maximum width of the tire, the upper edge of the inner reinforcing layer 9 made of an organic fiber cord is connected to the upper end of the outer reinforcing layer made of a steel cord in order to prevent a decrease in durability due to stress concentration. Raising the outer side of the tire in the radial direction of the tire, and making the interval between these edges 4 mm or more and 10 mm or less enables rigidity to be secured and a smooth change in rigidity to improve steering stability and durability. And can be compatible.

In the present invention, the belt structure, the carcass structure, and the reinforcing structure are not limited to the above-described embodiments, but may be variously changed as necessary. For example, as shown in FIG. 2, a structure may be employed in which the inner reinforcing layer 9 made of an organic fiber cord forms an upper end inside the bead filler 5. However, it is preferable to arrange the upper end of the inner reinforcing layer 9 outside the bead filler 5 as shown in FIG. 1 from the viewpoint of durability.

[0019]

EXAMPLE The tire size is common to 205 / 50R16, the roll-up height of the turn-up portion (CTU), the top height of the inner reinforcement layer (RU1), and the top height of the outer reinforcement layer (R).
U2), the upper end height of the bead filler (BFT), the lower end height of the inner reinforcing layer (RL1), and the lower end height of the outer reinforcing layer (R
L2), and the conventional tire 1 having the following configuration
-3, comparative tires and inventive tires 1-2.

As the organic fiber cord of the inner reinforcing layer, an aromatic polyamide fiber cord (1500 d / 2) was used, the driving density was 50 fibers / 50 mm, and the inclination angle with respect to the tire circumferential direction was 45 °. . On the other hand, as the steel cord of the outer reinforcing layer, 2 + 2 (0.2
5) Use steel cord and set the driving density to 4
0/50 mm, and the inclination angle with respect to the tire circumferential direction was 20 °.

Conventional tire 1 Tire structure: FIG. 3 Inner reinforcing layer: none Outer reinforcing layer: steel cord Positional relationship: CTU> RU1> BFT> RL1

Conventional tire 2 Tire structure: FIG. 4 Inner reinforcing layer: steel cord Outer reinforcing layer: steel cord Positional relationship: CTU>RU2>RU1>BFT>RL2>
RL1

Conventional tire 3 Tire structure: FIG. 5 Inner reinforcing layer: steel cord Outer reinforcing layer: steel cord Positional relationship: CTU>RU1>RU2>BFT>RL2>
RL1

Comparative tire Tire structure: FIG. 6 Inner reinforcing layer: organic fiber cord Outer reinforcing layer: steel cord Positional relationship: CTU>RU2>RU1>BFT>RL1>
RL2

Tire 1 of the present invention Tire structure: FIG. 1 Inner reinforcing layer: organic fiber cord Outer reinforcing layer: steel cord Positional relationship: CTU>RU1>RU2>BFT>RL1>
RL2

Tire structure 2 of the present invention Tire structure: FIG. 2 Inner reinforcing layer: organic fiber cord Outer reinforcing layer: steel cord Positional relationship: CTU>RU1>RU2>BFT>RL1>
RL2 For these test tires, steering stability, durability, and ride comfort were evaluated by the following test methods, and the results are shown in Table 1.

Driving stability: Test tires were inflated to 200k
It was mounted on a passenger car with a displacement of 1800 cc as Pa, and the feeling was evaluated by running on a circuit course with five test drivers. The evaluation result was 10 for the conventional tire 1.
The index was set to 0. The larger the index value, the better the steering stability.

Durability: Test tires are inflated at an air pressure of 180 kPa.
And running at a speed of 81 km / h, while gradually increasing the load from the initial condition of 463 kg, and measuring the traveling distance until a failure occurs in the bead portion or the side portion. The evaluation result was 10 for the conventional tire 1.
The index was set to 0. The greater the index value, the better the durability.

Ride comfort: Test tires were inflated to 200 kP
As a, it was mounted on a passenger car with a displacement of 1800 cc, and the feeling was evaluated by running on a circuit course with five test drivers. The evaluation result was 100 for the conventional tire 1.
And the index. The larger the index value, the better the ride comfort.

[0030]

[Table 1]

As is clear from Table 1, the tires 1 and 2 of the present invention were able to greatly improve the steering stability while suppressing the decrease in durability as compared with the conventional tire 1. Further, the tires 1 and 2 of the present invention also had good riding comfort. On the other hand, although the conventional tires 2 and 3 and the comparative tire obtained the effect of improving the steering stability, the durability was greatly reduced accordingly.

[0032]

As described above, according to the present invention, 1
In a pneumatic radial tire having a high turn-up structure of -1 configuration, an inner reinforcing layer composed of a plurality of organic fiber cords is wound up from the inside of the tire to the outside around the bead core between the inner carcass layer and the bead core and the bead filler. And an outer reinforcing layer composed of a plurality of steel cords is disposed between the turnup portion of the inner carcass layer and the outer carcass layer, and the winding height (CTU) of the turnup portion and the upper end of the inner reinforcing layer The height (RU1) and the upper end height (RU2) of the outer reinforcing layer are determined by CT.
By satisfying the relationship of U>RU1> RU2, an excellent reinforcing effect can be obtained while avoiding stress concentration. Therefore, even in the case of a flat tire for high-speed running, the durability is not impaired, and the moldability is improved. The steering stability can be greatly improved without causing deterioration.

[Brief description of the drawings]

FIG. 1 is a meridian half sectional view showing a pneumatic radial tire according to an embodiment of the present invention.

FIG. 2 is a meridian half sectional view showing a pneumatic radial tire according to another embodiment of the present invention.

FIG. 3 is a meridian half sectional view showing a conventional pneumatic radial tire.

FIG. 4 is a meridian half cross-sectional view showing another conventional pneumatic radial tire.

FIG. 5 is a meridian half cross-sectional view showing still another conventional pneumatic radial tire.

FIG. 6 is a meridian half-sectional view showing a pneumatic radial tire of a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bead part 2 Inner carcass layer 2a Turn-up part 3 Outer carcass layer 4 Bead core 5 Bead filler 6 Tread part 7 Belt layer 8 Belt cover layer 9 Inner reinforcing layer 10 Outer reinforcing layer

Claims (3)

[Claims] 1. An inner and outer carcass layer is mounted between a pair of left and right bead portions, and both end portions in the tire width direction of the inner carcass layer are wound around a bead core from the inside of the tire to the outside, respectively. In the pneumatic radial tire in which the bead filler arranged on the outer peripheral side of the bead core is wrapped and both ends in the tire width direction of the outer carcass layer are arranged outside the turn-up portion, respectively, the inner carcass layer, the bead core and the bead filler are provided. An inner reinforcing layer made of a plurality of organic fiber cords is arranged between the bead core so as to be wound up from the inside of the tire to the outside, and a plurality of steel layers are provided between the turn-up portion and the outer carcass layer. An outer reinforcing layer made of a cord is arranged, and a winding height (CTU) of the turn-up portion is provided. Upper end height (RU) of the inner reinforcing layer
1) The upper end height (RU2) of the outer reinforcing layer is determined by CTU
A pneumatic radial tire having a relationship of>RU1> RU2. 2. An upper end height (BF) of the bead filler.
T), the lower end height (RL1) of the inner reinforcing layer and the lower end height (RL2) of the outer reinforcing layer are expressed as CTU>RU1> RU.
The pneumatic radial tire according to claim 1, wherein a relationship of 2>BFT>RL1> RL2 is satisfied. 3. The pneumatic radial tire according to claim 1, wherein a distance between an upper end of the inner reinforcing layer and an upper end of the outer reinforcing layer is 4 to 10 mm.