JPH0438205A - Radial tire - Google Patents

Abstract

PURPOSE:To drastically improve steering stability and high speed durability by means of effectively restraining separation of a tire rubber from a cap layer due to lifting while heightening tread rigidity by forming the cap layer with a high tensile nylon monofilament coated with rubber. CONSTITUTION:A radial tire 1 is equipped with a tread part 2, a side wall part 3 extending from both edges of the tread part 2 inside in the tire radial direction and a bead part 4 positioned at the inner edge in the radial direction. In this case, a toroidal type carcass to lock both edges of a main body part to a bead core 5 around the bead core 5 by way of rewinding from inside to outside is installed over between the bead part 4, and simultaneously, a belt layer 7 and a cap layer 8 are sequentially wound around the outside of the carcass 6 in the radial direction. Then, the cap layer 8 is formed of a rubber coated high tensile nylon filament, for example, of more than one piece of cap plies 8A arrayed at the angle of 0 - 5 deg. in relation to the tire equator.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radial tire with improved high-speed durability.

C. Prior Art] In recent years, as automobiles have become faster, there has been a strong demand for improved high-speed running performance and high-speed durability of tires.

In addition, in order to satisfy such requirements, in the case of radial tires, conventionally, a cap layer in which nylon cords made of multiple nylon filaments twisted together and arranged approximately parallel to each other along the circumferential direction of the tire is placed on the outside of the belt layer. Place it in
By improving the circumferential rigidity of the belt layer and suppressing belt cord breakage, handling stability during high-speed running,
The durability is expected to be improved.

[Problem to be solved by the invention]

However, such a nylon cord has a coiled shape made by twisting a plurality of filaments, so it has poor tensile strength and high elongation, and therefore tends to lift due to centrifugal force caused by tire rotation during high-speed running.

Particularly in shoulder areas where the tension is low during tire molding, the lifting of the cord is significant, causing separation from the surrounding rubber and reducing the high-speed durability of the tire.

Moreover, such lifting causes an increase in the rolling resistance of the tire, and also increases the weight of the tire due to the formation of the cap layer, impairing improvements in running performance and fuel efficiency.

In view of this situation, the present invention is based on the use of high-tensile nylon monofilament, which has excellent tensile strength and low elongation, for the cap layer, thereby suppressing lifting of the cap layer and improving the high-speed durability of the tire. The purpose of the present invention is to provide a radial tire that can improve driving stability and handling stability, as well as reduce the weight of the tire.

[Means to solve the problem]

In order to achieve the above object, the radial tire of the present invention comprises a toroidal carcass that is wound around a pair of left and right bead cores and is locked at both ends, and one or more belt plies in which belt cords are arranged in parallel. and a belt layer disposed radially outwardly of the carcass, while a cap layer comprising one or more cap plies juxtaposed with rubberized high-tensile nylon monofilament is radially outwardly of the belt layer. It is set up.

Further, it is preferable that the high tensile strength nylon monofilament has an oval cross section and is arranged with its longitudinal axis aligned in the axial direction of the tire.

[Effect]

The cap layer of the radial tire configured in this way is 1
It is formed by arranging high tensile nylon monofilaments parallel to each other.

Therefore, by twisting a plurality of filaments (multifilaments) together into a coil, the elongation can be suppressed compared to conventional nylon cords.

Moreover, while a shearing force in the torsion direction acts on each filament of a conventional nylon cord during elongation deformation,
The shearing force does not act on this monofilament, increasing its tensile strength. Therefore, it is possible to increase the rigidity of the tread in the circumferential direction and to effectively suppress lifting caused by centrifugal force throughout the hit, greatly improving high-speed durability and high-speed handling stability while reducing uneven wear. .

In addition, this material can reduce the outer diameter compared to the apparent cord diameter of conventional nylon cords, reduces the cage thickness of the cap layer, and helps reduce the weight of the tire. When the cage is flattened, it is possible to achieve a further reduction in the cage thickness and a more uniform improvement in the trend in-plane rigidity.

(Concrete example〕 An embodiment of the present invention will be described below based on the drawings.

In the figure, a radial tire 1 includes a trend part 2, sidewall parts 3 extending inward in the tire radial direction from both ends of the trend part 2, and a corner part 4 located at the inner end in the radial direction.

In addition, in the bead portion 4.4, both ends of the main body from the tread portion 2, passing through the sidewall portion 3 and reaching the bead core 5 of the bead portion 4 are wound around the bead core 5 from the inside to the outside and locked. A toroidal carcass 6 is placed on the rack, and a belt layer 7 and a cap layer 8 are sequentially wound on the outside of the carcass 6 in the radial direction.

The carcass 6 is made of, for example, polyester, nylon,
In this example, carcass cords made of organic fibers such as rayon and aromatic polyamide are arranged at an angle of 60 to 90 degrees with respect to the tire equator.In this example, two inner and outer carcass plies 6A and 6B are used.
The end of the inner carcass ply 6 covers the end of the outer carcass ply 6B and is interrupted near the maximum middle position of the tire. This helps disperse stress concentrated at the ends of the ply. Also, the carcass 6
A bead apex 10 that tapers up from the bead core 5 toward the outside in the radial direction is interposed between the zero main body part and the turned-up part, and improves the tire lateral rigidity together with the high turn-up structure of the carcass 6.

The bead apex 10 is reinforced by, for example, a bead fin 9 folded back from the bottom surface of the bead core 5, thereby increasing the bead rigidity and preventing the carcass 6 from wearing against the bead core 5, which moves as the tire deforms.

Furthermore, a chafer 1 for preventing the rim from slipping is provided at the end portion 4.
1 is provided.

In addition to the Naori-cascord, inorganic fiber cords such as steel can also be used depending on the required tire performance.

In this example, the belt layer 7 is composed of two inner and outer belt plies 7A and 7B, and the ply width W7A of the inner belt ply 7A is 1.01 to 1. By making it about 20 times wider, it is possible to prevent the concentration of the difference in rigidity from the surrounding rubber due to the coincidence of the edges A and B.

In this example, each belt ply 7A, 7B is a cord array body in which steel belt cords are arranged parallel to each other at an angle of about 10 to 30 degrees with respect to the tire equator. A cross-ply structure in which the plies intersect with each other enhances the hoop effect and improves the uniformity of the tire.

Note that the outer belt ply 7B can be made wider than the inner belt ply 7A, and other suitable belt cords include polyester cord, nylon cord, aromatic polyamide fiber cord, carbon fiber cord, etc. In addition, the belt layer 7 may include a mixture of belt plies made of different belt cord materials.

In the present invention, a cap layer 8 is formed outside the belt layer 7 in the radial direction and inside the trend portion 2.

The cap layer 8 is composed of one or more cap plies 8A, usually one or two cap plies 8A, in which rubberized high-tensile nylon monofilaments 13 are arranged at an angle of 0 to 5 degrees with respect to the tire equator.
The both edges C of the belt layer 7 are formed from the edge A of the belt layer 7.
, B extend outward in the axial direction of the tire to cover the belt layer 7.

As the cap ply 8A, it is preferable to use a blind-like woven fabric in which high-tensile nylon monofilaments 13 parallel to each other are woven by weft threads, or one or more high-tensile nylon monofilaments 13 continuously spirally arranged in the circumferential direction of the tire. It can be formed as a multi-filament wound body.

In addition, in the case of such a wound body, cap ply 8A
has an endless shape and has substantially equal tension between the edges C and C to reinforce the trend portion 2.

Further, the high tensile strength nylon monofilament 13 is a single nylon filament obtained by further drawing and strengthening a thread material obtained by thread-proofing linear polyamide, and in this example, the cross section thereof is formed into an oval shape. Note that the elliptical shape includes, for example, an oval shape, which is a flattened perfect circle, as well as an ellipse shape, as shown in FIG. 2(a) to...). The axles are arranged in alignment with the tire axis direction. The high-tensile nylon monofilament 13 has a ratio a/b of the major axis to the minor axis of 1.
．． It is preferably 2.0 to 3.0, more preferably 2.0 to 3.0.

In this way, the cap layer 8 uses the high-tensile nylon monofilament 13 to increase its tensile strength and low elongation, so it can improve the circumferential rigidity of the trend part and effectively prevent lifting due to centrifugal force. can be suppressed to
High-speed steering stability and high-speed durability can be greatly improved while reducing uneven wear. Moreover, since the cap layer 8 is made of high-tensile nylon monofilament 13 that has been rubberized in advance,
It can prevent poor adhesion with tire rubber and further reduce separation during driving.

Furthermore, by making the cross-sectional shape of the high-tensile nylon monofilament 13 oblong, it is possible to greatly reduce the cage thickness in the radial direction of the cap layer 8 while maintaining high tensile strength and low elongation. , which can promote tire weight reduction.

Furthermore, the in-plane rigidity of the tread can be made uniform, which helps improve tire running performance.

〔Concrete example〕

It has the structure shown in Figure 1 and the tire size is 185/7.
A prototype 0R14 tire was manufactured based on the specifications shown in Table 1. t
The wear resistance, handling stability, high-speed durability, transferability, and weight of J Tire were compared with conventional tires based on the ECE30 standard, and the comparison results are listed in Table 1 as an index with Conventional Tire 1 set as 100. The physical properties and specifications of the nylon cord used in conventional tires and the high-tensile nylon monofilament used in example tires are shown in Table 2.The smaller the index value, the lighter the weight. The larger the index value, the better.

〔Effect of the invention〕

The radial tire of the present invention uses rubberized high-tensile nylon monofilament to form the cap layer, so it can effectively suppress separation from the tire rubber due to lifting while increasing tread rigidity, making it easier to maneuver. Stability and high-speed durability can be greatly improved. Moreover, the cage thickness of the cap layer can be reduced, making it possible to reduce the weight of the tire.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a tire showing one embodiment of the present invention, and FIG.
Figures (al and b) are cross-sectional views illustrating cross sections of high tensile strength nylon monofilament. 5- bead core, 7- belt layer, 8- cap layer, 13-- high tensile strength nylon monofilament.

Claims (1)

[Scope of Claims] 1. A toroidal carcass that is wound around a pair of left and right bead cores and locked at both ends thereof, and one or more belt plies in which belt cords are arranged in parallel, and that is radially outward of the carcass. 1. A radial tire comprising a belt layer disposed on the belt layer, and a cap layer using one or more cap plies arranged in parallel with rubberized high-tensile nylon monofilaments on the radial outer side of the belt layer. 2. The radial tire according to claim 1, wherein the high tensile strength nylon monofilament has an oval cross section, and the cap ply is arranged with the longitudinal axis of the high tensile strength nylon monofilament aligned in the tire axial direction. .