JPH04118307A - Radial tire - Google Patents

Abstract

PURPOSE:To improve the straight advance performance of a vehicle by reducing the torsional deformation of a belt layer by forming the belt layer between a tread and a carcass layer by attaching a single layer plate consisting of steel cords in S-twist direction and a single layer plate consisting of steel cords in Z-twist direction, keeping a prescribed cord angle. CONSTITUTION:As for a radial tire, a belt layer 14 is installed between a tread 10 and a carcasss layer 12. In this case, the belt layer 14 is formed by attaching single layer plates 16 and 18. The single layer plate 16 is formed from steel cords 20 having the twisting direction in S-twist, and the single layer plate 18 is formed from steel cords 22 having the twist direction in Z-twist. The S-twist means the twist in which the twist direction of steel cords is directed from the left upper part to the right lower part, drawing S figure shape. Further, the Z-twist means the twist in which the twist direction is directed from the right upper part to the left lower part, drawing Z figure form. Both the single layer plates 16 and 18 are attached, keeping a cord angle of 40-80 deg., and the belt layer 14 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radial tire for passenger cars.

[Prior Art and Problems to be Solved by the Invention] Conventionally, radial tires for passenger cars have been provided with a belt layer between a tread and a carcass layer. This belt layer is provided to ensure rigidity to suppress heat generation, improve grip between the tread and the road surface, and prevent damage sustained by the tread from directly reaching the carcass layer.

As shown in FIG. 5, this belt layer 114 is made by laminating two single-layer plates 116 and 118, and these single-layer plates 118 and 118 are made up of bundles of twisted steel cords 120 and 118.
These two single-layer plates 116 and 118 are bonded together so that the cord angle of the steel cord 120 has a predetermined angle.

By the way, when vertical stress is applied to this belt layer 114,
Shearing deformation occurs, and as shown in FIG. 6, torsional deformation occurs. Then, when the radial tire is pressed against a flat road surface, this twisting occurs at the contact surface, causing a deviation with respect to the direction of travel of the tire, and when the radial tire rotates, a minute slip angle occurs. Because of this slip angle,
There is a problem in that lateral force is generated and the vehicle moves in a direction different from the direction intended by the driver.

In particular, the steel cord 120 used in the belt layer 114
Since the direction of twist is the same for both single-layer boards,
There was a problem in that the torsional deformation of the belt layer 114 became larger.

[Object of the Invention] In view of the above problems, the present invention provides a radial tire that improves the straight running performance of a vehicle.

[Means for Solving the Problems] The radial tire of the present invention is a radial tire including a belt layer between a tread and a carcass layer, wherein the belt layer is made of steel cords made of east-twisted steel cords in the S-twist direction. A single-layer board made of steel cord and a single-layer board made of steel cord twisted in bundles in the Z-twisting direction are bonded together so as to have a predetermined cord angle.

[Function] With the radial tire having the above configuration, the twisting directions of the steel cords forming the two single-layer plates constituting the belt layer are different, so that torsional deformation can be reduced.

Therefore, by reducing the torsional deformation of the belt layer, the straightness of the vehicle is improved.

[Example] Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a partially cutaway radial cross-sectional perspective view of a radial tire showing one embodiment of the present invention.

Reference numeral 10 is a tread, and reference numeral 12 is a carcass layer.

Reference numeral 14 is a belt layer provided between the tread IO and the carcass layer 12. This belt layer 14 is a single layer plate I6
and a single layer plate 18 are bonded together.

The single layer board 16 is made of steel cord 20 with an S twist direction.
The single layer board 18 is formed from steel cords 22 with a Z-twisting direction.

Here, S-twist and Z-twist refer to the way in which the steel cord is twisted, and S-twist means that the steel cord is twisted in the direction from the upper left to the lower right, as shown in Figure 2. It is twisted in a way that makes it look like a figure eight. In addition, Z-twisting means that the steel cord is twisted in the direction from the upper right to the lower left, as shown in Figure 3, as if it were twisted in a two-letter pattern.

Then, as shown in FIG. 4, the single layer board 16 and the single layer board 8 are bonded together with a cord angle of 40' to 80' to form the belt layer 14.

Three types of radial tires were used in this experiment, the results of which will be described below, using the radial tires configured as described above to determine the straight running performance of the vehicle. One is a conventional radial tire, in which the two single-layer plates are each formed from S-twisted steel cord. The radial tire of Example 1 is an example of the present invention, in which the single layer plate on the surface side of the belt layer is formed of S-twisted steel cord 20, and the second layer single layer plate 18 is made of S-twisted steel cord 20. It is formed from two-stranded steel cord 22. In the radial tire of Example 2, the single layer plate 16 on the surface side of the belt layer 14 was formed from two-stranded steel cord 22, and the second layer single layer plate 18 was formed from S-twisted steel cord 20. It is.

The experimental conditions were that when a vehicle traveling at 100 kIIl/h traveled 100 m, the amount of deviation in the lateral direction with respect to the traveling direction was measured four times.

The results are shown in Table 1.

(The following is a blank space.) From the results in the table above, it can be seen that with the radial tire of the present invention, the amount of lateral deviation of the vehicle is smaller than with conventional radial tires, and the straight-line running performance of the vehicle is better. . This is because the twisting directions of the steel cords of the two single-layer plates forming the belt layer are different from each other, which reduces torsional deformation of the belt layer.

[Effects of the Invention] As described above, in the radial tire of the present invention, since the directions of twisting of the steel cords of the two single-layer plates constituting the belt layer are different, the straight-line running performance of one vehicle can be sufficiently improved. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway radial cross-sectional perspective view of a radial tire showing an embodiment of the present invention, FIG. 2 shows a steel cord with an S twist direction, and FIG. Fig. 4 is an exploded perspective view of the belt layer, Fig. 5 is a perspective view of the belt layer of a conventional radial tire, and Fig. 6 is a steel cord with two twists in the same direction. FIG. 2 is a perspective view of the belt layer in a state where the belt layer is torsionally deformed. [Explanation of symbols] 10...Tread 12...Carcass layer 14...Belt layer 16...Single layer plate 18...Single layer Plate 20...Steel cord 22...Steel cord Patent applicant: Toyo Rubber Industries, Ltd. Figure 2 Figure 1 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. A radial tire comprising a belt layer between a tread and a carcass layer, wherein the belt layer is a single-layer plate formed from steel cords twisted in bundles in the S-twist direction. , a radial tire characterized in that a single-layer plate formed from steel cords twisted in bundles in the Z-twisting direction is laminated so as to have a predetermined cord angle.