JPH01297306A - Pneumatic radial tyre for heavy load - Google Patents

Abstract

PURPOSE:To enhance the rigidity of the sidewall portion of a tyre by disposing a reinforcing layer formed by the lamination of two organic fiber cord layers in mutually intersected relationship inside a carcass ply which goes from the shoulder portion to the bead portion via the sidewall portion of the tyre. CONSTITUTION:A tyre is provided with a carcass 1 formed by turning one piece of turn-up ply from the inside back to the outside in the circumference of a bead core 5 and a belt layer 2 formed by the lamination of plural cord layers of steel cord in mutually intersected relationship. In this case, two pieces of putty formed of organic fiber cord are laminated to each other in such a manner that their respective cords may intersect with each other so as to form a reinforcing layer 3. And the reinforcing layer 3 is disposed along the inner side of the carcass 1 from the shoulder portion including the end of the belt layer 2 to the area in the bead portion where the turn-up portion of the carcass ply is located via the sidewall portion of the tyre. The rigidity of the sidewall portion is thus surely and simply enhanced.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to heavy-duty pneumatic radial tires such as those for trucks or buses, and in particular relates to techniques for improving characteristics on wet road surfaces, so-called wet resistance. I will explain.

In order to improve wet resistance, it is effective to suppress deformation of the sidewall portion of the tire. In other words, it suppresses the deformation of the sidewall part due to the force applied in the tire circumferential direction on the tire contact surface during braking and driving, and improves ground contact by preventing the tire contact surface from being deformed forward or backward in the direction of tire rotation. It will come true.

(Conventional technology) Regarding increasing the rigidity of the sidewall part of a tire,
U.S. Pat. No. 4,231,409 discloses a reinforcing layer placed on the outside of the carcass plies and extending to the ends of the belt layer.

(Problems to be Solved by the Invention) However, in the tire manufacturing process, it is difficult to manufacture because it is necessary to apply a reinforcing layer to the side part of a raw tire that has been formed into a shape similar to the product on a molding drum. When a reinforcing layer is placed outside the ply, a stiffener that extends higher than the ply end is interposed between the carcass ply and the reinforcing layer, separating the reinforcing layer from the ply. cannot be stacked to form the sides of a triangle, and the desired rigidity cannot be obtained;
remains a problem.

Therefore, an object of the present invention is to propose a structure that can suppress deformation of the sidewall portion of a tire and is easy to manufacture.

(Means for Solving the Problems) This invention consists of a ply in which cords are arranged parallel to each other in a direction perpendicular to the equatorial plane of the tire, and at least one ply is arranged around a pair of bead cores from the inside of the tire. A belt layer comprising a toroidal carcass having an outwardly wound folded portion and at least one cord layer in which cords arranged parallel to each other are arranged substantially parallel to the equator of the tire; At least two cord layers in which organic fiber cords are arranged in parallel are placed inside the carcass ply in the area where the folded portion of the carcass ply exists from the shoulder portion of the tire through the sidewall portion and the bead portion, the cords intersecting each other. This is a heavy-duty pneumatic radial tire with reinforcing layers laminated in such an arrangement.

Now, FIG. 1 illustrates the structure of a heavy-duty pneumatic radial tire according to the present invention.

In the figure, 1 is a carcass, 2 is a belt layer, 3 is a reinforcing layer, 4 is a tread, and 5 is a bead core.

In this example, the carcass 1 is a single turn-nap bra that is wound around the bead core 5 from the inside of the tire to the outside.

The belt layer 2 is formed by laminating two cord layers made of steel cords in such a manner that the cords cross each other.

The reinforcing layer 3 is made by laminating two plies made of organic fiber cords in such a way that the cords cross each other.
At least as shown in the illustrated example, it is disposed inside the carcass 1 in the area where the folded part of the carcass ply exists from the shoulder part of the tire including the end part of the belt layer 2, through the sidewall part, and the one end part. Note that the appropriate angle for the cords to intersect is 40° to 65° with respect to the circumferential direction.

Further, the reinforcing layer 3 may be disposed at least in the region from the shoulder portion to the bead portion of the tire (the reinforcing layer 3 may be disposed as shown in FIGS. 2 to 4).

On the other hand, as a method of suppressing the deformation of the tire sidewall, there is a method of setting the ply end position of the folded part of the carcass ply near the maximum middle position of the carcass ply or higher than that. A structure of a pneumatic radial tire according to the present invention is shown in FIG.

The belt layer 2 is the same as that shown in FIG. Reinforcement layer 3
is made by laminating two plies made of organic fiber cords in such a way that the cords intersect with each other, and at least as shown in the example shown, the ply is formed by laminating two plies made of organic fiber cords, and at least as shown in the example shown in the figure, from the shoulder part of the tire including the two ends of the belt layer through the sidewall part. It is arranged inside the carcass l in the area where the folded part of the carcass ply exists.

(Function) By arranging the reinforcing layer inside the carcass, the laminated shape of the carcass ply and the reinforcing layer can be maintained at any position.
It can be triangular, as shown by , thus ensuring the necessary stiffness.

By disposing the reinforcing layer on the inside of the carcass, pasting during manufacturing is easy and can be done on a conventional molding drum.

The reason why the reinforcing layer is arranged in the area from the shoulder part to the bead part of the tire is to prevent separation from occurring at the end of the reinforcing layer. In other words, the region where the belt layer exists (shoulder part) and the region where the braai folding part exists (bead part) have high rigidity and deformation during transfer is small, so if the end of the reinforcing layer is placed within these regions, the end of the reinforcing layer It can reduce stress concentration on.

However, when the reinforcing layer extends to the folded portion side of the carcass (see FIG. 4), the end of the reinforcing layer may be arranged higher than the ply end. This is because the end of the reinforcing layer is not in close contact with the folded braai, so a triangular laminated shape is not formed and stress concentration on the end of the reinforcing layer is small.

(Example) Heavy-duty tires of size 10.00R20 with a radial structure carcass using plies of steel cord were manufactured with the structures shown in Figures 1 to 4 and Figures 7 and 8, and each tire was The results of evaluation regarding wet resistance and durability are shown in the table below. Regarding durability evaluation, tires with structures shown in FIGS. 9 and 10 were also manufactured and evaluated for comparison. The tread-side end of the reinforcing layer 3 of the tire shown in FIG. 9 is not located in the shoulder area of the tire including the belt layer end. On the other hand, the end of the reinforcing layer 3 of the tire shown in FIG. 10 near the bead portion does not reach the area where the folded portion of the carcass ply exists. In addition, wet resistance is evaluated by the braking distance on a wet road surface, and durability is evaluated by measuring the kilometers traveled until separation occurs while driving on the drum.In both cases, the measurement results are A conventional tire to which the structure shown in Figure 6 is applied is 1
It is shown as an index when it is set to 00. The smaller the index of wet resistance, the larger the index of durability, the better the properties.

(Effects of the Invention) According to the present invention, the rigidity of the sidewall portion required for improving the wet resistance of heavy-duty pneumatic radial tires used for trucks and buses can be achieved with an easy-to-manufacture structure. Ru.

[Brief explanation of the drawing]

1 to 5 are cross-sectional views showing the bead structure according to the present invention; FIG. 6 is an explanatory view showing the laminated shape of the carcass ply and the reinforcing layer; FIGS. 7 and 8 are cross-sectional views of the conventional bead portion; and 1
Figure 0 is a cross-sectional view of a comparative example. 1...Carcass 1a...Ply end 2...
・Belt layer 3... Reinforcement layer 4... Tread 5... Bead core Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1. Consisting of a ply in which cords are arranged parallel to each other in a direction perpendicular to the equatorial plane of the tire, at least one
The ply consists of a toroidal carcass having a folded part wound from the inside to the outside of the tire around a pair of bead cores, and at least one cord layer having cords arranged in parallel to each other substantially parallel to the equator of the tire. organic fiber cords are arranged in parallel inside the carcass ply in the region where the folded part of the carcass ply exists from the shoulder part of the tire including the end of the belt layer, through the sidewall part, and the bead part. A heavy-duty pneumatic radial tire comprising a reinforcing layer in which at least two cord layers are laminated in such a manner that the cords cross each other.