JP3412892B2 - Pneumatic tire - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire which can achieve weight reduction without impairing tire strength and is useful for reducing tire noise.

[0002]

2. Description of the Related Art Generally, a bead portion of a tire is provided with an annular bead core in which steel cords are wound in multiple stages in order to fix an end portion of a carcass and keep a tight fit with a rim.

On the other hand, with the recent improvement in vehicle performance and fuel efficiency, there is a strong demand for reduction (weight reduction) of tire weight, and improvement in bead core is also required.

In recent years, as a bead cord which replaces the steel cord, filaments f of organic / inorganic fiber other than metal such as glass fiber and aromatic polyamide are aligned in parallel as shown in FIG. Some cords and cords having a single twist structure in which these are twisted as shown in FIG. 6 have been proposed.

[0005]

However, since the filaments are poorly united, it is difficult to form them on the bead core. Therefore, at the time of forming the cord, each filament f is coated with a resin such as hard polyurethane, or For example, resorcin-formalin-latex system (RFL) which is used to enhance the adhesion between the cord and the rubber.
It was necessary to immerse the cord itself in a (type) resin and harden the cord itself with a large amount of resin. For this reason, the strength of the cord is greatly reduced to lower the bead strength, and the rigidity of the bead core becomes excessive, impairing the rim assembling property and causing a problem of insufficient tightening force to the rim. .

[0006] The present invention has a basic that also regulates the twist multiplier of the adopted and encodes the filtrate twisted structure as bead wires, fillers without fixing a code with a large amount of resin
It is an object of the present invention to provide a pneumatic tire capable of improving the cohesiveness of the ment and solving the above problems.

[0007]

In order to achieve the above object, the pneumatic tire of the present invention comprises an annular bead core using a bead cord in a bead portion, and the bead cord has an elastic modulus of 3000 kgf. / mm ² or more bundles of filaments of organic fibers at least two further another direction strands of the same size made to fit twisted in one direction, the lower
It has the same number of twists as the number of twists , and it has a structure that is entangled, and the square root of the total number of denier of the bead cord is √D.
Twisting coefficient K (= T multiplied by the number T of cord twists per 0 cm)
· √D) with a 500 to 1300, and processing of resin
The coating amount of the resin is beaded while coating the physical fluid.
It is characterized by being 5 to 12% by weight with respect to the weight of the cord .

[0008]

[Function] The bead cord has a twisted structure. In this case, since the directions of the lower twist and the upper twist are different, the friction between the filaments is further increased. Furthermore, since the twisting coefficient K is greatly increased to 500 to 1300 , the mutual effect of these increases the cohesiveness of each filament even when a highly elastic organic filament is used, so that a large amount of resin can be fixed. May be unnecessary.

Therefore, the characteristics of the cord material itself can be sufficiently exhibited, the bead strength can be enhanced, the bead rigidity can be relaxed to enhance the rim assembly property, and the rim can be effectively tightened. Even when a high twist coefficient in the above range is used, the elastic modulus of the filament is 3000 kgf / mm ² or more, so that the required tightening force can be obtained.

Further, the relaxation of the bead rigidity and the improvement of the tightening force to the rim can reduce the transmission rate of the noise vibration transmitted from the tread to the rim through the bead portion, and suppress the tire noise.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the figure, a tire 1 includes a pair of sidewall portions 3 extending inward in the tire radial direction from both ends of a tread portion 2.
And a bead portion 5 located at the radially inner end of each sidewall portion 3, and in this example, the tire size is 195 /
It is formed as a 65R15 radial tire for passenger cars.

As shown in an enlarged view in FIG. 2, the bead portion 5 is provided with an annular bead core 7 having a plurality of wound cords 6 wound around it. A carcass 9 folded from the inside of the tire to the outside of the tire around the bead core 7 from the tread portion 2 to the sidewall portion 3 is bridged between the bead cores 7 and at the outer side in the radial direction of the carcass 9. A belt layer 10 is wound around the inside of the tread portion 2 in the circumferential direction.

The bead core 7 is formed by continuously winding one or a plurality of long cords 6 in the circumferential direction, and the cords 6 are entangled structure using filaments f of organic fibers. The thing of is adopted.

More specifically, as shown in FIGS. 3 and 4, the cord cord 6 has at least two strands 13 of the same size , which are formed by twisting a bundle of filaments f in one direction. It is formed by twisting in two directions, and in this example, a so-called two-strand twist structure using two strands 13 is formed.

Further, in the moly-twist structure, the number of twists on one side (the number of lower twists) and the number of twists on the other side (the number of upper twists) are the same, and the square root of the total denier number D of the cord √ The twist coefficient K (= T · √D) obtained by multiplying D by the twist number T of the cord per 10 cm is 500 to 1300.
The range is greatly increased.

As described above, by adopting the loose twist structure having a high twist coefficient K, it is possible to enhance the restraining force between the filaments f and obtain sufficient cohesiveness of the filaments. When the twisting coefficient K is less than 500, the filaments are not sufficiently united to form a bead core, and when the twisting coefficient K is more than 2000, the elastic modulus of the cord is excessively reduced, and the necessary tightening force to the rim is required. Cannot be secured.
Therefore, the twist coefficient K is preferably in the range of 850 to 1300.

The filament f has an elastic modulus of 30.
It is necessary to use organic fibers of 00 kgf / mm ² or more, preferably 4000 kgf / mm ² or more. For example, aromatic polyamide fibers and aromatic polyester fibers can be used. In this example, fragrances whose strength is less dependent on temperature are used. Group polyamide fibers are used. The elastic modulus is 3000 kgf / mm
^{When it is} less than ² , the tightening force of the bead core 7 becomes insufficient.

Further, the bead cord 6 may be coated with a treatment liquid made of, for example, a resorcin-formalin-latex type (RFL type) resin in order to enhance the adhesion with the rubber of the tire. At this time, the adhesion amount of the resin is regulated within the range of 5 to 12% by weight with respect to the weight of the bead cord 6 to which the resin is attached. That is, the characteristics of the cord itself are maintained by restricting it to the minimum range necessary for adhesion with rubber.

(Concrete example) Using the bead core described in the specifications of Table 1, a tire with a tire size of 195 / 65R15 was prototyped, and the tire weight, tire breaking pressure, bead tightening force and noise novel of this prototype tire were measured. Each was measured and compared with a conventional tire.

[0020]

[Table 1]

[0021]

As described above, since the pneumatic tire of the present invention adopts the loose twist structure as the bead cord and the twist coefficient of the cord is greatly increased, the cohesiveness of the filament can be improved, It is possible to achieve weight reduction without reducing tire strength and reduce tire noise.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a tire showing an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing an enlarged bead core.

FIG. 3 is a diagram illustrating the structure of a hide code.

FIG. 4 is a schematic cross-sectional view of a cord.

FIG. 5 is a diagram illustrating a conventional code.

FIG. 6 is a diagram illustrating a conventional code.

[Explanation of symbols]

5 bead part 6 Hed code 7 bead core 13 strands f filament

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-56-43010 (JP, A) JP-A-50-82705 (JP, A) JP-A-49-85705 (JP, A) JP-A-6- 262911 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B60C 15 / 04,9 / 00

Claims (3)

(57) [Claims] 1. A bead portion is provided with an annular bead core using a bead cord, and this bead cord is formed by twisting a bundle of organic fiber filaments having an elastic modulus of 3000 kgf / mm ² or more in one direction. Two same size
Other direction strands further twisted over as many as the number of twists
It has a twisted structure in which the number of denier is 10 cm.
Twist coefficient K (= T · √
D) is set to 500 to 1300, and the resin treatment liquid is coated, and the coating adhesion amount of the resin
Be 5 to 12% by weight based on the weight of the bead cord.
Pneumatic tire characterized by. 2. The organic fiber comprises an aromatic polyamide
The treatment liquid is RFL type.
Pneumatic tire described. 3. The pneumatic tire according to claim 1, wherein the twist coefficient K is 850 to 1300.