JPH1044713A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve trail wandering resistance by arranging edge cover layers with single steel wires wound being individually arranged parallel to the circumfernetial direction of a tire, at both end parts on the outermost side of a belt layer. SOLUTION: A belt layer 7 formed of two plies that are an inner belt ply 7a and an outer belt ply 7b is provided at the periphery of a carcass layer 4 in a tread part 1. These belt plies 7a, 7b are arranged intersecting each other at a cord angle of 15-30 deg. to the circumferntial direction of a tire. Edge cover layers 9 are respectively arranged at the peripheries of both end parts of the outer belt ply 7b. In these edge cover layers 9, single steel wires formed in corrugated or spiral shape in a longitudinal direction are individually wound in spiral shape so as to be arranged parallel to the circumferential direction. A layout angle of the single steel wires to the circumferential direction of the tire is to be practically 0 deg. and 10 deg. or less at the maximum.

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, and more particularly, to a pneumatic radial tire capable of improving rut wandering resistance even when a steel wire is used for an edge cover layer of a steel cord belt layer. Regarding tires.

[0002]

2. Description of the Related Art In general, a pneumatic radial tire is provided with two belt layers made of a steel cord on the outer periphery of a carcass layer for passenger cars and three or more belt layers for large vehicles. When such a radial tire having a belt structure runs at high speed, the end of the belt layer rises due to centrifugal force, causing a separation failure with rubber, and an increase in the contact pressure of the shoulder portion, causing uneven wear. Was.

[0003] For this reason, in a high-speed pneumatic radial tire for a passenger car, the belt layer is required to prevent the belt layer from rising due to centrifugal force during high-speed running, to prevent uneven wear, and to increase durability. An edge cover layer made of a synthetic fiber cord made of heat-shrinkable nylon or the like is disposed at both ends of the cover. Further, in the case of large radial tires for heavy loads, it has been proposed to dispose an edge cover layer made of a steel cord in place of a synthetic fiber cord because the strength of the synthetic fiber cord is insufficient. 5
-69702).

However, since the steel wire cord has a structure in which a plurality of single wires are twisted, there is a problem that the edge cover layer is thick, the rigidity of the shoulder portion is increased, and the rutting wandering resistance is reduced. . That is, the rut wandering property is essential for a high-load radial tire having three or more steel cord belt layers, and various other avoidance measures are taken. Even in a radial tire for a light truck having a two-layered cord belt layer, there is a problem that the wandering resistance is reduced.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic radial tire having two steel cord belt layers as a means for suppressing the belt edge from rising due to centrifugal force. An object of the present invention is to provide a pneumatic radial tire that can improve rudder wandering resistance while using layers.

[0006]

According to the present invention, there is provided a pneumatic radial tire in which a belt layer made of two steel cords is arranged on the outer periphery of a carcass layer. An edge cover layer in which a single wire of a corrugated or helically shaped steel wire is individually wound around the portion so as to be arranged substantially in parallel to the tire circumferential direction is arranged.

[0007] As described above, since the edge cover layer is formed by arranging the single wires of the steel wire independently in parallel, the thickness of the edge cover layer can be reduced and the rigidity of the shoulder portion can be reduced. Performance can be improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on an embodiment shown in the drawings. FIG. 1 shows a radial tire for a light truck. A sidewall portion 2 and a bead portion 3 are respectively connected to left and right sides of a tread portion 1, and a carcass layer having a cord angle of substantially 90 ° with respect to the tire circumferential direction is provided inside the sidewall portion. The carcass layer 4 is folded back so that both ends surround a bead filler 6 having a substantially triangular cross section from the inside to the outside of the tire around left and right bead cores 5.

As shown in FIG. 1 and FIG. 2, a belt layer 7 composed of two plies, an inner belt ply 7a and an outer belt ply 7b, is arranged on the outer periphery of the carcass layer 4 in the tread portion 1. These belt plies 7a, 7
b are arranged so as to cross each other between the plies at a cord angle of 15 to 30 ° with respect to the tire circumferential direction, and the edge cover layers 9 are arranged on the outer periphery of both ends of the outer belt ply 7b.

The edge cover layer 9 is spirally wound with a predetermined width so that the steel wire single wires 8 formed in a wavy or spiral shape in the longitudinal direction are arranged independently and substantially parallel to the tire circumferential direction. And is embedded in a rubber sheet. The arrangement angle of the single steel wire 8 with respect to the tire circumferential direction is substantially 0 °, and the maximum is 10 °.
° or less. If the arrangement angle exceeds 10 °, the effect of suppressing the rise of the edge of the belt layer at the time of high-speed running cannot be sufficiently achieved.

The single steel wire 8 is inextensible, but is shaped in a wavy or spiral shape in the longitudinal direction, so that it can follow the lift during vulcanization of the tire. The lift rate during tire vulcanization (the ratio of the diameter at which the outer diameter of the green tire expands to the inner diameter of the mold) is usually 1 to
Since it is 5%, the elongation rate of a single steel wire is 5
% Is preferable. With such an elongation ratio, smooth vulcanization molding can be performed even when a steel wire is used for the edge cover layer.

As described above, in the pneumatic radial tire of the present invention, when a steel wire is used for the edge cover layers disposed at the outermost ends of the belt layer, a single wire of a steel wire formed in a wavy or spiral shape is used. Since the edge cover layer is thinly wound so as to be arranged in parallel alone, the rigidity of the shoulder portion can be reduced, and the rudder wandering resistance can be improved. The above-described present invention has a remarkable effect when applied to a light truck or a passenger car having two steel cord belt layers.

[0013]

FIG. 1 shows a tire size of 205 / 70R16.
Having a common structure in which the belt layer is made of steel cord, and the edge cover layer has a diameter of 0.3 mm.
The tire of the present invention configured to be wound at 0 ° with respect to the tire circumferential direction from a single steel wire of φ, and a diameter of 0.20 mm
Conventional tires having a configuration in which a steel cord in which a single steel wire of φ had a 2 + 2 twist structure was wound at 0 ° with respect to the tire circumferential direction were manufactured.

These two types of tires were evaluated for rut wandering resistance, high-speed durability, and uneven wear resistance by the following test methods. Table 1 shows the results of the evaluation. Test method: Rutting resistance: Wear tires on 2t truck,
Feeling evaluation was performed by three drivers while actually traveling on a rutted general road, and the index was expressed as an index with the evaluation of the conventional tire being 100. The larger the index value is, the better the rut wandering resistance is. High-speed durability: JIS D-4230, after completion of the JIS high-speed durability test, the running distance was measured every 30 minutes until the tire was broken by accelerating at 10 km / hr. The measured value of the conventional tire is represented by an index value with 100 being set. The higher the index value, the higher the high-speed durability. Uneven wear resistance: 100% with tire mounted on 2t truck
After traveling 50,000 km on the pavement, the amount of uneven wear was measured by a laser displacement meter. The evaluation was performed using the reciprocal of the measured value, and was represented by an index with the measured value of the conventional tire being 100. The larger the index value, the better the uneven wear resistance.

[0015] From the results shown in Table 1, it can be seen that the tire of the present invention has the same high-speed durability and uneven wear resistance as the conventional tire, and has improved rut wandering resistance.

[0016]

As described above, the pneumatic radial tire of the present invention is constituted by winding a single wire of a steel wire in which the edge cover layers disposed at the outermost ends of the belt layer are formed in a wavy or spiral shape. Therefore, by reducing the thickness of the edge cover layer, the rigidity of the shoulder portion can be reduced, and the rutting wandering resistance can be improved.

[Brief description of the drawings]

FIG. 1 is a half sectional view showing an example of a pneumatic radial tire of the present invention.

FIG. 2 is a partially enlarged schematic plan view showing the inside of a tread of the tire of FIG. 1;

[Explanation of symbols]

 Reference Signs List 4 Carcass layer 7 Belt layer 7a Inner belt ply 7b Outer belt ply 8 Steel wire single wire 9 Edge cover layer

Claims (1)

[Claims] 1. A pneumatic radial tire in which a belt layer made of two steel cords is arranged on an outer periphery of a carcass layer, a steel wire formed in a wavy or spiral shape at each of outermost ends of the belt layer. A pneumatic radial tire having an edge cover layer in which single wires are wound so as to be arranged substantially in parallel in the tire circumferential direction.