JPH06143946A - Structure of bead part for pneumatic tire - Google Patents

Abstract

PURPOSE:To achieve both satisfactory controllability and riding quality and facilitate the lightening and molding of a tire for high speed traveling. CONSTITUTION:This tire is provided with a first carcass ply 9 of a high turn-up folded back along the outward surface 6a of a bead apex 6, a second carcass ply 10 having the lower end interrupted in a position spaced above a bead core 5 and a protective layer 13 enveloping a reinforcing layer 11 using steel cords extending vertically outside the outward surface 6a and the bead core.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a bead portion of a pneumatic tire for a tire for high speed running, which has improved steering stability, reduced weight, and is easily molded.

[0002]

2. Description of the Related Art In recent years, with the development of highway networks, passenger cars are becoming faster, and even light vans and light trucks are becoming faster and heavier. Flatness of 60% for tires used for
The following flat tires have become widely used. In such a flat tire, it is necessary to increase the rigidity of the sidewall portion and the bead portion in order to secure the movement performance of the vehicle, and it is difficult to achieve both steering stability and riding comfort.

Conventionally, in a tire aiming at high performance, a carcass a is formed by using two carcass plies b, b as shown in FIG. 4, and each carcass ply is A so-called 2-0 structure in which the bead core c of the bead portion c is wound in the same direction is common.

[0004]

However, when the carcass has the 2-0 structure, it becomes difficult to secure sufficient lateral direction, front-rear direction and torsional rigidity, and to achieve both steering stability and riding comfort. . Further, the carcass structure of 2-0 causes a problem that the weight of the tire increases.

As a result of various trials and experiments conducted by the inventor to solve the above problems, a) a carcass is composed of two carcass plies, one of which is a bead core and is folded up from the inside to the outside to a high position. The so-called 1-that rolls up and lowers the other one
1 configuration,

(B) It was found that the above problems can be solved by further reinforcing the bead portion with a reinforcing layer, and the present invention has been completed.

An object of the present invention is to provide a structure of a bead portion of a pneumatic tire which is lightweight and can maintain steering stability even in a flat tire.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a tread portion is passed through a sidewall portion to be folded back from an inner side to an outer side at a bead core of a bead portion, and is folded back along an outer surface of a bead apex extending upward from the bead core. A first carcass ply having a turn-up portion with a high turn-up structure, passing from the tread portion to the sidewall portion and passing between the turn-up portion and the outward surface of the bead apex, and the lower end is cut off at a position above the bead core. Second carcass ply, between the outward surface of the bead apex and the second carcass ply, between the second carcass ply and the folded portion of the first carcass ply, or the folded portion of the first carcass ply. Reinforcement layer using steel cords arranged on the outer side of the car and extending vertically in the radial direction, and the main body of the first carcass ply A rewind portion that rises between the inward surface of the bead apex and wraps around the bead core and folds back from the inner side to the outer side of the bead apex and rewinds along the outer surface of the bead apex and the upper end of which is interrupted below the lower end of the reinforcing layer. The structure of a bead portion of a pneumatic tire having a protective layer using an organic fiber cord.

[0009]

The first carcass has a turn-up portion having a high turn-up structure that is folded back along the outward surface of the bead apex, and the second carcass ply has the turn-up portion and the outward surface of the bead apex. The lower end is interrupted at a position that passes through the space and is separated upward from the bead portion. Thereby, by forming the carcass of the 1-1 structure by the first and second carcass plies and forming the shell structure, it is possible to optimize the tension distribution of the first and second carcass plies, and It is possible to secure riding comfort while enhancing the rigidity in the lateral direction, the front-back direction, and the twist in the portion.

Further, the total length of the plies is shorter than that of a conventional construction in which two carcass plies as shown in FIG. 4 are folded back in the same direction, and the carcass can be lightened accordingly.

Further, since the second carcass ply is passed between the first carcass ply and the bead apex, the molding is facilitated, and the lower end of the second carcass ply is interrupted at a position separated upward from the bead core, so that the force variation is reduced. Will not be invited.

In addition, since the reinforcing layer using the steel cord is arranged on the outer side of the bead apex, the sidewall portion and the bead portion can be effectively reinforced and the steering stability can be further enhanced.

Further, by providing a protective layer for wrapping the bead core inside the main body of the first carcass ply, the dimensional accuracy of the bead can be increased and the finish of the bead can be improved.

As described above, according to the present invention, by organically integrating and integrating the above-mentioned components, it is possible to achieve both steering stability and riding comfort even for a flat tire, and to reduce the weight. In addition, the molding can be facilitated, and the force variation is good, and the economical production can be achieved.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the structure of the bead portion of the pneumatic tire (hereinafter referred to as the structure of the bead portion) has a flatness of 60% in this example.
The following flat tire 1 includes a tread portion 2 forming a tread surface 2A and a pair of sidewall portions 3 and 3 extending inward in the tire radial direction from both sides thereof.
And a bead portion 4 extending inward of the sidewall portion 3.

Further, in the tire 1, the tread portion 2 extends from the sidewall portion 3 to the inside of the bead core 5 of the bead portion 4 and is folded back from the inner side to the outer side 6a of the bead apex 6 extending upward from the bead core 5. A first carcass ply 9 having a folded-back portion 7 and a tread portion 2 extending from the sidewall portion 3 between the folded-back portion 7 and the outward surface 6a of the bead apex 6 and extending downward. The carcass 8 comprises two carcass plies 10.

In this embodiment, the belt layer 15 is provided inside the tread portion 2 and outside the carcass 8, and the band layer 16 for preventing the lifting of the belt layer 15 is provided outside the belt layer 15. It The bead apex 6 has an elongated triangle shape made of rubber harder than the sidewall rubber 17 forming the outer wall of the sidewall 3.

The first and second carcass plies 9, 10
Has a radial or semi-radial carcass cord in which organic fibers such as nylon, polyester, rayon, and aromatic polyamide are inclined with respect to the tire equator C and arranged in parallel with each other.
Has a so-called high turn-up structure in which the upper end of the folded-back portion 7 is located above the tire maximum width point B. Further, the second carcass ply 10 has its lower end located at a position spaced apart from the bead core 5 above, and the 1-1HTU is formed by these first and second carcass 9, 10.
The carcass 8 having the structure is formed.

A reinforcing layer 11 is disposed on the outside of the outward surface 7 of the bead apex 6. In this embodiment shown in FIG. 1, the reinforcing layer 11 is vertically arranged between the outward surface 6a and the second carcass ply 10, and the upper end thereof is above the tip P of the bead apex 6 and at the upper end of the folded portion. On the other hand, the lower end of the second carcass ply 10 is positioned at substantially the same height as the lower end of the second carcass ply 10. The reinforcing layer 11 is a sheet body formed by arranging steel cords side by side and covering the cords with a topping rubber.

As shown in FIG. 2, the reinforcing layer 11 is provided between the second carcass ply 10 and the folded portion 7 of the first carcass ply 9, and further as shown in FIG. It may be arranged outside the folded-back portion 7 of 9 so as to face the sidewall rubber 17.

The bead portion 4 rises between the main body portion of the first carcass ply 9 and the inward surface 6b of the bead apex 6, wraps the bead core 5 and is folded back from the inside to the outside. The bead apex 6 is provided with a protective layer 13 which is rewound along the outward surface 6a and has a rewound portion 12 whose upper end is interrupted below the lower end of the reinforcing layer 11. The protective layer 13 is a tough and flexible sheet body in which a fabric made of organic fibers such as nylon and aromatic polyamide fibers is covered with a topping rubber, and enhances and reinforces the molding accuracy of the bead portion.

The belt layer 15 comprises a plurality of belt plies 15a in which organic fibers such as nylon, rayon, aromatic polyamide fibers or steel cords are arranged at an angle of 15 to 85 ° with respect to the tire equator C. It is formed by stacking the sheets, and the rigidity of the tread portion 2 is enhanced.

Further, in this embodiment, the band layer 16 is arranged outside the belt layer 15 of the tread portion 2. Band layer 1
Reference numeral 6 includes an inner band ply 16a that covers the entire surface of the belt layer 15 and a small outer band ply 16b that is disposed outside the belt ply 16 and reinforces both end portions of the belt layer 15.

The inner and outer band plies 16a and 16b are long lengths in which a single or plural organic fiber cords such as nylon or aromatic polyamide fibers are covered with a topping rubber,
It is formed by spirally winding a narrow band-shaped ply in the tire circumferential direction, and prevents lifting of the belt layer 15 during high-speed running, which improves high speed and prevents peeling of the end portion of the belt layer 15 so as to withstand high loads. To improve durability and durability.

[0025]

[Specific example] Tire size is 205 / 55R15 87V
And the tire (Example) having the configuration shown in FIG. 1 was tested for its performance. The same size and Fig. 4
A conventional tire (comparative example) having the configuration shown in (1) was also subjected to a running test to compare the performance.

The test tires were mounted on a 2000 cc passenger car and the following tests were conducted. a) Circuit lap time A lap time of about 3.7 km was lapped and the lap time was measured for each lap.

B) Ride Comfort The driver's sensory sensation when traveling on rough asphalt roads, joints, roads with many protrusions, etc. was evaluated on a 5-point scale. Three
Indicates the average, and the larger the number, the better.
The test results are shown in Table 1.

[0028]

[Table 1]

As a result of the test, the circuit lap time of the example is longer than that of the comparative example by about 1.0 second, and the high speed and the steering stability are improved, and at the same time, the riding comfort is secured. I was able to confirm that I was able to do it.

[0030]

As described above, the structure of the bead portion of the present invention is
By providing the above-mentioned configuration, it is possible to secure riding comfort performance while improving steering stability and reduce the weight of the tire, and it is possible to economically produce a tire that is easy to mold and has a good force variation.

[Brief description of drawings]

FIG. 1 is a right half sectional view of a tire showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing another mode of the bead portion.

FIG. 3 is a cross-sectional view showing another mode of the bead portion.

FIG. 4 is a cross-sectional view showing a conventional technique.

[Explanation of symbols]

 2 tread portion 2A tread surface 3 sidewall portion 4 bead portion 5 bead core 6 bead apex 6a outward facing surface 7 folding portion 8 carcass 9 first carcass ply 10 second carcass ply 11 reinforcing layer 12 winding portion 13 protective layer C Tire equator

Claims (1)

[Claims] 1. A folded-back portion having a high turn-up structure which is folded back from the tread portion to the sidewall portion at the bead core of the bead portion from inside to outside and along the outward surface of the bead apex extending upward from the bead core. A first carcass ply having, a second carcass ply having a lower end that is cut off at a position above the bead core, passing from the tread portion to the sidewall portion, between the folded-back portion and the outward surface of the bead apex, and the bead. Between the outward surface of the apex and the second carcass ply,
A reinforcing layer using a steel cord that is arranged between the second carcass ply and the folded-back portion of the first carcass ply or outside the folded-back portion of the first carcass ply and extends vertically in the radial direction, and the first carcass. It rises between the main body of the ply and the inward surface of the bead apex, wraps the bead core and folds back from the inside to the outside, and rewinds along the outward surface of the bead apex and the upper end is below the lower end of the reinforcing layer. A structure of a bead portion of a pneumatic tire having a continuous rewound portion and a protective layer using an organic fiber cord.