JP2001334809A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic radial tire, capable of lightening a tire and reducing a rolling resistance by suppressing an occurrence of belt end separation and a bending of cord with a good tire performance. SOLUTION: A metal mono-filament or a wire bundle aligned two- dimentionally with a belt layer of tire comprises three belt plies 3, 4 and 5, arranged at an isolated position in parallel to a belt ply direction and buried in a rubber. A diameter of the mono-filament is desirable between 0.10 mm or more and 0.40 mm or less and a desirable thickness of the belt layer is below 2.1 mm.

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 which is reduced in weight without impairing various performances of the tire, and more particularly to a pneumatic radial tire suitable as a radial tire for a passenger car. .

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for reducing the weight of tires in order to improve fuel efficiency of automobiles. As an effective means of reducing weight, steel cords for tire reinforcement belts have been reviewed, and new technologies have been disclosed for their structures and configurations. For example, JP-A-11-
No. 91311 discloses a technique in which a single metal wire is spirally formed in advance and a belt cord having a large attenuation is used, and it is described that the tire can be reduced in weight and riding comfort can be prevented from lowering. Also, in JP-A-10-292275,
A reinforcing belt was proposed in which several metal monofilaments were buried in rubber as a bundle aligned in the width direction without twisting, and it was described that rolling resistance and riding comfort were improved and belt edge separation was also suppressed. I have.

However, it has been found that the above-mentioned prior art has the following problems. That is, in the spirally shaped belt cord of JP-A-11-91311, since the diameter of the metal wire is large, a large strain is generated on the surface of the metal wire when bending deformation is repeatedly applied during traveling, and the There is a disadvantage that the metal wire is easily broken when a large bending deformation is applied during road running.

Further, in a reinforcing belt made of a metal wire bundle aligned in the width direction of Japanese Patent Application Laid-Open No. Hei 10-292275,
Although the separation at the belt end has been improved, the problem of insufficient bending stiffness of the belt still remains and needs to be improved.

[0005]

SUMMARY OF THE INVENTION Accordingly, in order to meet the need for further weight reduction of tires, the present invention uses a non-twisted metal wire as a tire reinforcing belt, and at the same time, breaks the above-mentioned metal wire. It is an object of the present invention to solve problems such as a decrease in durability due to the above.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been devoted to the structure of a metal monofilament, the arrangement in a belt ply, and the construction of a belt layer, typically a steel monofilament. As a result of research, the present invention has been completed.

That is, the pneumatic radial tire of the present invention
A carcass layer comprising at least one radial carcass ply straddling in a toroidal manner between a pair of bead cores, and a tread layer disposed outside the crown region of the carcass layer in the tire radial direction to form a ground contact portion A pneumatic radial tire, comprising: a belt layer formed of a belt ply forming a reinforcing portion disposed between the tread layer and the crown region of the carcass layer. It is characterized by comprising three belt plies arranged in the ply width direction and embedded in the covering rubber.

Here, at least one belt ply of the belt layer is such that a single line of a metal monofilament is arranged substantially uniformly spaced apart in the width direction of the belt ply and embedded in a covering rubber; It is advantageous in implementation that the monofilament single wire driving density is 30 or more per 50 mm width of the belt ply.

At least one belt ply of the belt layer is a metal wire bundle which is aligned in parallel in the width direction of the belt ply without twisting a plurality of metal monofilaments, and is separated from each other in the width direction. It is advantageous in practice to be laid out and arranged in the covering rubber.

[0010] Further, the metal monofilament is preliminarily formed into a spiral or wavy shape, and the angle between the center line of the metal monofilament in the outermost belt ply in the radial direction and the tire equatorial plane is substantially changed. Is preferably 0 ° in order to improve the riding comfort and shock absorption of the tire.

The angle between the metal monofilaments in at least two adjacent belt plies and the equatorial plane of the tire is 15 to 35 °, and the angle between the metal monofilaments in the remaining one belt ply and the equatorial plane of the tire is. Larger values are also preferred.

Further, the diameter of the metal monofilament is
Being not less than 0.10 mm and not more than 0.40 m; and
It is advantageous for the implementation that the total thickness of the belt layer is 2.1 mm or less.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A pneumatic radial tire according to one embodiment of the present invention will be specifically described with reference to FIGS.

The pneumatic radial tire of the present invention has a carcass layer 2 composed of at least one radial carcass ply straddling in a toroidal manner between a pair of bead cores 1 and a tire diameter in a crown region of the carcass layer. A tread layer disposed outside in the direction to form a ground portion, and a belt layer including a belt ply forming a reinforcement portion disposed between the tread layer and the crown region of the carcass layer, FIG. 2 or FIG.
As shown in FIG. 1, metal monofilaments are arranged in the width direction of the belt ply, and are composed of three belt plies (3, 4, 5) embedded in the covering rubber.

Since the belt layer of the present invention is composed of three belt plies, the number of metal monofilaments or metal wire bundles per belt ply may be reduced, or a filament having a small diameter may be used. However, high belt bending rigidity can be maintained. As a result, the distance between the metal monofilaments or the metal wire bundle can be widened, and the generation and propagation of separation (separation) in the belt layer or at the belt end can be effectively suppressed. In addition, since a filament with a fine wire diameter can be applied, the strain on the metal wire surface during repeated bending deformation during tire running can be reduced, and even when large bending strain is applied, the metal wire is hard to break and durable Excellent in nature.
Here, the driving density of the metal monofilament is desirably 30 or more per 50 mm of the width of the belt ply. If it is less than this, the rigidity of the belt layer is insufficient, and the penetration resistance when stepping on a nail or the like is insufficient. There is a risk of going bad.

The diameter of the metal monofilament of the present invention is:
It is preferable that it is not less than 0.10 mm and not more than 0.40 mm. If it is less than 0.10 mm, there may be a shortage of three belt plies to secure the bending rigidity of the belt layer. If the diameter exceeds 0.40 mm, the strain on the surface of the metal wire when repeatedly subjected to bending deformation increases, and there is a concern that the metal wire is easily broken and the durability is reduced.

In practicing the present invention, there are two forms, a form in which a metal monofilament is used as a single wire, and a form in which a metal monofilament is used as a bundle of metal wires aligned in the width direction. Preferably 2 to
The use of a metal wire bundle in which six metal monofilaments are aligned in parallel in the width direction of the belt ply without being twisted allows a wider interval between the bundles,
It is desirable because peeling of the belt layer and its propagation can be more effectively suppressed.

In general, in the case of a tire for a passenger car, there is a concern that the use of three belt plies may increase the weight of the tire. However, in the present invention, by applying a metal monofilament having a small diameter, By reducing the ply thickness per sheet and not increasing the tire weight,
A lightweight belt layer consisting of three belt plies was made possible. Here, the total thickness of the belt layer is preferably 2.1 mm or less to make the tire lighter than the conventional tire.

Since the belt layer of the present invention can be configured in various ways by combining three belt plies of various specifications, it is possible to increase the degree of freedom and flexibly cope with designing a tire having special functions and characteristics. There are advantages.

[0020]

Embodiments of the present invention will be described below with reference to the drawings and tables. In this embodiment, the diameter, the structure or the arrangement, the tensile strength, and the equatorial plane of the metal wires shown in the column 1B to 3B ply of Table 1 are applied to the pneumatic radial tire having the cross-sectional structure shown in FIG. A belt layer produced by bonding belt plies 1B to 3B having specifications such as an angle to be formed and the number of struck pieces in order from the 1B ply in the radial direction is applied. Here, R and L added to the angle
Indicates whether the angle formed by the cord with the tire equator is a right angle or a left angle.

[0021]

[Table 1]

The belt layer of Example 1 is composed of three belt plies in which metal monofilaments of 0.26φ are arranged in the width direction of the belt ply, and the angle between the filaments of the radially inner ply and the equator of the filament is 52 ° (so-called “equator”). Low angle). The belt layer of Example 2 is composed of three belt plies in which metal monofilaments of 0.21φ are arranged in the ply width direction, and the angle between the filaments of the outermost ply in the radial direction and the equator is 52 ° (low angle). is there.

Examples 3 and 4 are examples in which a metal monofilament preliminarily spirally molded is used for the outer 3B ply.
They are arranged substantially parallel to the tire circumferential direction. Example 5
Is a high-strength metal monofilament having a small diameter, a gauge between metal cords of 1B ply and 2B ply, 2B ply and 3B ply.
This is an example in which the gauge between the metal cords of the B ply is thinned. Example 6 is the same as Example 5 except that a large-diameter metal monofilament is used for the 1B ply. Example 7 is an example in which four bundles of monofilaments are applied to each belt ply.

Comparative Examples 1 and 2 are each composed of two belt plies, Comparative Example 1 uses a (1 × 3) twisted cord, and Comparative Example 2 is an example using a thick monofilament. is there.

Test tires were manufactured using the above nine belt layers. The lower part of FIG. 1 shows the evaluation results of the tire durability, which were evaluated based on the thickness and weight of the belt layer and the belt breakability of each prototype tire. In each case, the performance of Comparative Example 1 was 10
A relative evaluation index of 0 indicates that the lower the belt weight index and the higher the durability index, the better the performance. The tire of the present invention is composed of three belt plies, the total thickness of the belt layer is 1.98 mm or less, and the weight of the belt is 16 to 40% lighter than that of Comparative Example 1. The durability index is also improved by 3 to 25% as compared with Comparative Example 1. The tire of the present invention was found to be lightweight and excellent in durability, despite being composed of three belt plies.

The method of testing for belt breakage performed in the present embodiment is as follows.

<Belt Breaking Test> In this test, the test tire was mounted on an actual vehicle, and after traveling 30,000 km at a speed of 60 km / h on a curved road, the test tire was dissected, and the test tire was dissected. Reinforcing members (wire bundles or cords) were sampled, the number of the reinforcing members in a broken state was investigated, and the reciprocal thereof was indicated as an index with the conventional tire as 100. The higher the index, the better the belt refraction resistance.

[0028]

As described above, the pneumatic radial tire according to the present invention improves various problems caused by weight reduction, that is, various tire performances such as separation resistance and belt break resistance at a belt end. It was found that the tire was a lightweight pneumatic radial tire with low rolling resistance.

[Brief description of the drawings]

FIG. 1 is a left half sectional view of a pneumatic radial tire according to the present invention.

FIG. 2 is an example of three belt plies on which a metal monofilament according to the present invention is uniformly driven.

FIG. 3 is an example of three belt plies in which four metal monofilaments according to the present invention are arranged in a bundle.

[Explanation of symbols]

 1 Bead core 2 Carcass layer 3 1B ply of belt layer 4 2B ply of belt layer 5 3B ply of belt layer

Claims (9)

[Claims] 1. A carcass layer comprising at least one radial carcass ply straddling in a toroidal manner between a pair of bead cores, and a ground contact portion disposed outside a crown region of the carcass layer in a tire radial direction. A pneumatic radial tire comprising: a tread layer that forms a belt layer; and a belt layer that is disposed between the tread layer and the crown region of the carcass layer and that is formed of a belt ply that forms a reinforcing portion. A pneumatic radial tire comprising three belt plies in which metal monofilaments are arranged in the width direction of the belt ply and embedded in a covering rubber. 2. The at least one belt ply of the belt layer according to claim 1, wherein a single line of a metal monofilament is arranged substantially uniformly spaced apart in the width direction of the belt ply and embedded in the covering rubber. Pneumatic radial tire. 3. The pneumatic radial tire according to claim 2, wherein the density of the single filament of the metal monofilament is 30 or more per 50 mm width of the belt ply. 4. The at least one belt ply of the belt layer is a metal wire bundle that is arranged in parallel in the width direction of the belt ply without twisting a plurality of metal monofilaments, and is separated between the bundles in the width direction. The pneumatic radial tire according to any one of claims 1 to 3, wherein the pneumatic radial tire is arranged and buried in a covering rubber. 5. The pneumatic radial tire according to claim 1, wherein the metal monofilament is formed into a spiral or wavy shape in advance. 6. The pneumatic radial tire according to claim 5, wherein an angle formed by a center line of the metal monofilament in a radially outermost belt ply with a tire equatorial plane is substantially 0 °. 7. The angle between the metal monofilaments in at least two adjacent belt plies and the tire equatorial plane is 15 to 35 °, and the angle between the metal monofilaments in the remaining one belt ply and the tire equatorial plane is The pneumatic radial tire according to any one of claims 1 to 4, which is larger than the above. 8. The diameter of the metal monofilament is:
The pneumatic radial tire according to any one of claims 1 to 7, wherein the diameter is not less than 0.10 mm and not more than 0.40 mm. 9. The pneumatic radial tire according to claim 1, wherein a total thickness of the belt layer is 2.1 mm or less.