JPH09175111A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve uneven wearing resistance and simultaneously enhance a damping effect, in a pneumatic radial tire for a truck from small size to large size required for a high load. SOLUTION: In a pneumatic radial tire having a pair of bead parts, carcass 3 continued in toroidal shape to the bead part and two sheets or more of main belt crossing layers 2 hooping a crown part of the carcass 3, the first belt layer 1 of a 15 to 40 deg. belt angle is arranged between the main belt crossing layer 2 and the carcass 3, with a 0.25mm or less steel filament diameter of the first belt layer 1, 58 to 64 deg. belt angle of the main belt crossing layer and a 4.0kg/cm<2> or more internal pressure at use time are used.

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 for trucks, which has a high damping effect and, at the same time, an improved uneven wear resistance and a long service life, and which has a long life. Regarding

[0002]

2. Description of the Related Art A tire for a truck, which is required to have a high load, is filled with a high internal pressure in order to support the load.
Further, in recent years, such tires have tended to have a lower floor due to an increase in the loading capacity, and accordingly, there has been a tendency to flatten the outer diameter of the tire.

However, when the flatness of the tire is reduced, the damping effect of the tire is reduced, so that the shock when a vehicle passes over a small step on the road is increased, and the steering wheel is easily taken when the vehicle runs on a rutted road. The problem comes out. Such a problem also contributes to a decrease in side portions due to flattening of the tire, that is, uneven wear. In order to solve this problem, attempts have been made to reduce the belt angle of the tire belt to reduce the rigidity of the belt and thereby to enhance the damping effect of the tire.

On the other hand, in recent years, a case in which a belt having a simplified structure made of thick steel filament is applied to the belt layer in order to prevent the propagation of moisture from the cut portion by impregnating the steel cord of the belt with rubber. Is increasing.

[0005]

As in the prior art, if the belt angle of the main interlacing belt layer is lowered to increase the damping effect and the belt rigidity is lowered, the diameter growth of the tire due to the internal pressure filling is increased, so that the main interlacing is increased. Excessive compression force will be applied to the first belt layer between the layer and the carcass ply. As a result, a stress proportional to the filament diameter is generated on the surface of the steel filament used in such a belt layer, causing buckling plastic deformation during running of the tire, causing uneven wear, and eventually shortening the life. Will lead to

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to improve the damping effect and at the same time improve the uneven wear resistance in pneumatic radial tires for trucks of small to large sizes which are required to have a high load.

[0007]

In order to solve the above problems, a pneumatic radial tire of the present invention comprises a pair of beads, a carcass connected to the beads in a toroidal shape, and a crown of the carcass. In a pneumatic radial tire having two or more main belt crossing layers to be tightened, a first belt layer having a belt angle of 15 to 40 ° is provided between the main belt crossing layer and the carcass, and The steel filament diameter of the first belt layer is 0.25 mm or less, and the belt angle of the main belt crossing layer is 58 to 6
It is 4 ° and the internal pressure during use is 4.0 kg / cm ²
The above is the feature.

The pneumatic radial tire of the present invention preferably has an aspect ratio of 70% or less.

The steel cord of the first belt layer preferably has rubber permeability.

Further, a wrapping wire or a wrapping organic fiber is preferably wound around the steel cord of the first belt layer.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the pneumatic radial tire of the present invention, as shown in FIG. 1, a so-called low belt angle between the main belt crossing layer 1 and the carcass ply 3 is 15-40 °. By disposing one belt layer 2 and setting the steel filament diameter of this first belt layer to 0.25 mm or less, strain (stress) generated on the belt cord filament surface is reduced, and thereby buckling plastic deformation is suppressed. The uneven wear due to the abnormal deformation of the tire is prevented.
Here, the belt angle is the angle of the belt cord with respect to the tire radial direction as shown in FIG.

If the outermost layer filament of the steel cord of the first belt layer at a low belt angle has a weak restraining force when a compression force is applied to the tire belt, the filament is likely to be buckled and plastically deformed. The filament can be constrained by impregnating it with rubber, or the constraining force can be increased by winding a wrapping wire or wrapping organic fiber around the outer circumference of the cord. Thereby, it is possible to further prevent plastic deformation due to buckling (compressive) stress.

The structure of the steel cord used in the first belt layer may be the structure used in the belt layer of the conventional pneumatic radial tire for trucks, and it should be particularly limited except for the filament wire diameter. Not a thing. The twist structure of the belt cord may be a so-called closed twist structure with no gaps between filaments, but as a so-called open twist structure with gaps between filaments, it enhances the permeability of rubber inside the cord and also enhances the binding force. Therefore, it is preferable to wrap. Specifically, FIG.
As shown in (a) to (c), a 1 × 5 closed twist structure, a 1 × 5 open twist structure, a 1 × 5 + 1 structure with a wrapping wire and the like can be mentioned. The number of cords driven into the belt layer is preferably 20 to 40 cords / 5
cm.

When the belt angle of the first belt layer exceeds 40 °, the shear strain between the carcass ply and the first belt layer becomes large, so that peeling occurs between the carcass ply and the first belt layer. It will be easier. On the other hand, when the angle is less than 15 °, the shear strain between the main crossing layer (second belt layer) and the first belt layer becomes large, and similarly peeling easily occurs.

If the diameter of the steel cord filament of the first belt layer exceeds 0.25 mm, it becomes difficult to enhance the damping effect of the tire. That is, it becomes difficult to reduce the shock when overcoming a small step on the road, such as a seam of a bridge, and to reduce the behavior of the vehicle when traveling on a road with a rut.

In the present invention, the main crossing layer of the belt has a belt angle of 58 to 64 °. When the belt angle is smaller than 58 °, the rigidity in the circumferential direction is lowered, and the steering stability and the wear resistance are lowered. On the other hand, if it is larger than 64 °, the circumferential rigidity becomes too high, and it becomes difficult to enhance the damping effect. The steel cord used in this belt layer may be the steel cord having the wire diameter and structure used in the belt layer of a conventional pneumatic radial tire for trucks, and the number of cords to be driven is preferably 20 to 32 / It is 5 cm.

Further, the pneumatic radial tire of the present invention has an internal pressure of 4.0 kg / cm ² or more during use. This is because if the pressure is less than 4.0 kg / cm ² , the tire diameter growth due to the internal pressure filling does not increase so much, and therefore the compression input to the first belt layer is hardly generated.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. A pneumatic radial tire for a light truck having a first belt layer having a cord structure shown in Table 1 below (size:
205 / 60R17.5) was prototyped. The number of steel cords driven into the first belt layer was selected so that the total strength of the first belt layer treat would be constant. The main crossing layer is composed of two belt layers, both of which are 3 × 0.17.
The number of driven steel cords having a structure of 5 + 6 × 0.30 (mm) was 28.4 lines / 5 cm, and the belt angle was 60 °.

For these prototype tires, a constant volume load of 4
The amount of uneven wear when traveling 10,000 km was measured. As shown in FIG. 4, the uneven wear amount is the residual groove amount D at the center of the tread.
It was obtained as a difference (Dc-Ds) between c and the residual groove amount Ds of the shoulder portion. The results obtained are also shown in Table 1 below.

[0020]

[Table 1]

[0021]

[Table 2] * A wrapping wire with a wire diameter of 0.15 mm is applied.

[0022]

As described above, in the pneumatic radial tire of the present invention, the damping effect is enhanced and the behavior of the vehicle when traveling on a road with a shock or a rut when riding over a small step on the road. At the same time, the effect that the uneven wear resistance is improved can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an example pneumatic tire of the present invention.

2A and 2B are plan views showing belt angles of the main belt intersecting layer, respectively. (C) is a plan view showing the belt angle of the first belt layer.

3A to 3C are cross-sectional views of belt steel cords.

FIG. 4 is an explanatory diagram showing an uneven wear amount.

[Explanation of symbols]

 1 Main belt crossing layer 2 1st belt layer 3 Carcass ply

Claims (4)

[Claims] 1. A pneumatic radial tire having a pair of bead portions, a carcass connected in a toroidal shape to the bead portions, and two or more main belt intersecting layers for tightening the crown portion of the carcass, A first belt layer having a belt angle of 15 to 40 ° is arranged between the main belt intersecting layer and the carcass, and a steel filament diameter of the first belt layer is 0.25 mm or less. A pneumatic radial tire having a layer belt angle of 58 to 64 ° and an internal pressure of 4.0 kg / cm ² or more during use. 2. The pneumatic radial tire according to claim 1, which has a flatness of 70% or less. 3. The pneumatic radial tire according to claim 1, wherein the steel cord of the first belt layer has rubber permeability. 4. The pneumatic radial tire according to claim 1, wherein a wrapping wire or a wrapping organic fiber is wound around the steel cord of the first belt layer.