JPS6181803A - Pneumatic radial tire for passenger car - Google Patents

Abstract

PURPOSE:To improve high speed performance and comfortability, and reduce weight, by forming a belt layer with a carbon fiber cord belt layer arranged on a carcass layer side and an aromatic polyamide fiber cord belt layer arranged on a tread portion side. CONSTITUTION:A belt layer 5d formed of a carbon fiber cord C is arranged on a carcass layer 4 side, and a belt layer 5U formed of an aromatic polyamide fiber P is arranged on a tread portion 3 side. At least one layer of the belt layer 5U on the tread portion side is folded at one end to the tread portion side. With this arrangement, an impact force from a road surface is absorbed by the belt layer 5U formed of the aromatic polyamide fiber cord P having good anti-flexural fatigue to thereby improve durability of the belt layer 5. Further, it is possible to prevent separation of the belt layer 5d formed of the carbon fiber cord C at the folded portion. Thus, high speed performance and comfortability may be improved, and weight may be reduced.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a pneumatic radial tire for passenger cars, and more specifically, the present invention relates to a pneumatic radial tire for passenger cars. This invention relates to a pneumatic radial tire for passenger cars.

[Conventional technology]

``With the development of expressways, the demands on tires have become increasingly severe, and steel radial tires have emerged as a tire to meet these demands, replacing conventional bias tires.

Steel radial tires have a pair of left and right bead sections,
The carcass layer, in which reinforcing cords are arranged substantially at 90 degrees to the circumferential direction of the tire, is covered with a multi-layered helment 14 reinforced with steel cords, resulting in high speed, handling stability, and wear resistance.

It has various excellent performances as a tire, such as low rolling resistance.

However, on the other hand, there remains a problem in ride comfort due to the strength of the plurality of belt layers reinforced with the steel cords.゛In addition, in terms of weight, although efforts have recently been made to reduce the weight to approximately the same extent as compared to bias tires of equivalent size, the current situation is that they are reaching their limits.

Furthermore, since the multiple belt layers reinforced with steel cords have a large mass, the centrifugal force of the tires due to high-speed rotation may cause the belt layers to heave up, causing separation failure at both ends of the belt layers. It is also reaching its limits in terms of speed.

[Purpose of the invention]

The present invention was developed as a result of experiments and studies to solve the above-mentioned problems.

Therefore, an object of the present invention is to provide an excellent pneumatic radial tire for passenger cars that can improve high speed and ride comfort and also reduce the weight of the tire by devising the structure of the belt layer. It is in.

[Structure of the invention]

That is, the present invention comprises a pair of left and right bead portions, a pair of left and right sidewall portions connected to the bead portions, and a tread portion located between the sidewall portions, and a tread portion located between the pair of left and right bead portions in the circumferential direction of the tire. A carcass layer having a cord angle of 70° to 90° with respect to the tire circumferential direction is mounted, and a plurality of belt layers intersecting each other with a cord angle of 10° to 35° with respect to the tire circumferential direction are arranged on the carcass layer in the tread portion. In the pneumatic radial tire for passenger cars, among the belt layers, a belt layer made of carbon fiber cords is arranged on the carcass part side, and a belt layer made of aromatic polyamide fiber cords is arranged on the tread part side, Further, the present invention provides a pneumatic radial tire for a passenger car, characterized in that the end portion of at least one layer of the tread side belt layer made of the aromatic polyamide fiber cord is bent toward the tread side.

〔Example〕

Hereinafter, the present invention will be specifically described by way of examples with reference to the drawings.

FIGS. 1(a) to 1(d) show pneumatic radial tires for passenger cars according to embodiments of the present invention, FIG. b)～
(d) is a partially cutaway explanatory diagram showing the main parts of the second to fourth embodiments.

In the figure, E indicates a pneumatic radial tire for a passenger car according to an embodiment of the present invention, which includes a pair of left and right bead portions 1, a pair of left and right sidewall portions 2 connected to the bead portions 1,
It consists of a tread part 3 located between each sidewall part 2, and a carcass layer 4 having a cord angle of 70° to 90° with respect to the tire circumferential direction is mounted between the pair of left and right bead parts 1, Further, on the carcass layer 4 in the tread portion 3, the cord angle with respect to the tire circumferential direction is 10° to 3°.
It is constructed by arranging a plurality of belt layers 5 that intersect each other at an angle of 5°.

In the present invention, in particular, a belt layer 5d made of carbon fiber cord C is arranged on the carcass layer 4 side of the belt layer 5, and a belt layer 5u made of aromatic polyamide fiber cord P is placed on the tread portion 3 side. Further, the end portion of at least one layer of the tread portion side belt layer 5u made of the aromatic polyamide fiber cord P is treaded.

It is folded towards the side.

As described above in the present invention, since the carbon fiber cord C is used as the reinforcing cord of the carcass side belt layer 5d, (al) ,
The out-of-plane bending rigidity of the belt layer can be reduced. Therefore, the impact force when riding over a protrusion can be alleviated, and riding comfort can be significantly improved.

(b) When the total strength is the same, the weight can be reduced compared to a belt layer using steel cord as the reinforcing cord. Therefore, high speed performance can be improved.

The carbon fiber cord C used as the reinforcing cord for the carcass side belt layer 5d has a tensile strength of 100 kg/+u2 or more.

Preferably 200 kg/ws2 or more.

Tensile modulus...5000 kg/x weight 2 or more.

Preferably 15,000 kg/f12 or more.

After applying an adhesive in an amount of 10 to 50% of the weight per unit length of the carbon fiber to carbon fiber having the characteristics of It is preferable to use a cord made by adding twist to the cord.

K=TJD However, K...Twist coefficient T...Number of twists of the cord (twists/10cm) D...Total denier number of the cord and the twist structure are determined by adding first twist to each of several carbon fibers. After that, it may be possible to have a loosely twisted structure in which several of these carbon fibers are further combined and additionally twisted, or it may be a single twisted structure in which a single thread-like carbon fiber is twisted.

Furthermore, in the present invention, as mentioned above, since the aromatic polyamide fiber cord P is used as the reinforcing cord of the tread part side belt layer 5u, the carcass part side belt layer 5d using the carbon fiber cord C as the reinforcing cord mentioned above For similar reasons, it is possible to significantly improve ride comfort compared to conventional steel radial tires, while also increasing high speed.

The aromatic polyamide fiber cord P used as the reinforcing cord for the tread side belt layer 5u has a tensile strength of 150 kg/w2 or more.

Tensile modulus: 3000 kg/tm 2 or more.

It is preferable to use an aromatic polyamide fiber having the following characteristics, which is twisted so that the twist coefficient K expressed by the following formula is in the range of 1000≦≦2500, and then made into a cord and subjected to adhesive heat treatment.

K=T, /D However, K...Twist coefficient T...Number of twists of the cord (twists/10cm) D...Total denier number of the cord In addition, in the present invention, as mentioned above, in particular, the belt Of N5, a belt layer 5d made of carbon fiber cord C is arranged on the carcass layer 4 side, while a belt layer 5d made of carbon fiber cord C is placed on the tread portion 3 side so as to cover the outside of this carcass side belt layer 5d.
A belt layer 5u made of aromatic polyamide fiber cord P is arranged. In other words, the belt layer 5d made of carbon fiber cord C is replaced by the belt layer 5d made of aromatic polyamide fiber cord P which has better bending fatigue resistance than this belt layer 5d.
Covered by 5u.

Therefore, the belt layer 5u made of aromatic polyamide fiber cord P with excellent bending fatigue resistance can absorb the impact force from the tire tread.
Therefore, the durability of the heald layer 5 can be improved.

In addition, if a belt layer made of aromatic polyamide fiber cord P is arranged on both the carcass layer 4 side and the tread portion 3 side, the rigidity in the tire circumferential direction will be insufficient, and in particular, there is a risk that the steering stability will be inferior to that of conventional steel radial tires. I don't like it because it exists.

Further, as described above, the end of at least one layer of the tread side belt layer 5u made of the aromatic polyamide fiber cord P having excellent bending fatigue resistance is bent toward the tread side.

Therefore, the end of the tread side belt layer 5u can be made into two layers, and the protection of the carcass side belt layer 5d made of carbon fiber cord C can be greatly improved. It is also possible to prevent both ends of the belt a from rising due to centrifugal force, and to prevent separation failure from occurring.

The first embodiment of the present invention shown in FIG. This is an example in which one heald layer 5u is arranged.

Note that both left and right ends of the tread section side belt JEi 5 u made of the aromatic polyamide fiber cord P are bent toward the tread section side.

Embodiment 2 of the present invention shown in FIG. This is an example in which one belt layer 5u is arranged.

Note that both left and right ends of the tread portion side belt Fi5u made of the aromatic polyamide fiber cord P are bent toward the tread portion side.

In the third embodiment of the present invention shown in FIG. 1(C), a belt layer 5d made of carbon fiber cord C is arranged on the carcass layer 4 side, and the tread portion 3 is made of aromatic polyamide fiber cord P. This is an example in which two belt layers 5u are arranged.

Note that one end of each tread side belt layer 5u made of the aromatic polyamide fiber cord P is bent toward the tread side while facing each other.

In the fourth embodiment of the present invention shown in FIG. 1(d), a belt layer 5d made of carbon fiber cord C is arranged on the carcass layer 4 side, and a belt layer 5d made of aromatic polyamide fiber cord P is placed on the tread portion 3 side. This is an example in which two belt layers 5u are arranged.

In addition, in each tread portion side belt layer 5u made of the aromatic polyamide fiber cord P, only the upper belt layer is bent at both left and right ends toward the tread portion side, as shown in the figure.

As described above, in the present invention, 1. A plurality of belt layers 5d made of carbon fiber cords C located on the carcass layer 4 side may be arranged, or aromatic polyamide fiber cords located on the tread portion 3 side. Of course, a plurality of belt layers 5u made of P may be arranged.

[Experiment example]

In order to confirm the effects of the present invention, the following tests were conducted.

(Specifications of tires used in each test) Tire of the present invention> Tire size: 195/70R14° Carcass layer: A 1000 d'/2 polyester cord was used as a reinforcing cord. Two layers were arranged so that the angle was 90' with respect to the tire circumferential direction.

Carcass layer side belt layer...1800 d as reinforcement cord
/2.

Twist coefficient = 600 (Moro-twist structure 10 times/10cm) carbon fiber coat Cord angle is 21° to the tire circumferential direction. I arranged it further so that

Tread side belt layer...1500 d as reinforcement cord
/ 2 aromatic polyamide fiber cords were arranged in a single layer so that the cord angle was 24° with respect to the tire circumferential direction, and both left and right ends were bent toward the tread portion.

<Conventional tire> Tire size: 195/70R14° Carcass layer: A 1000 d/2 polyester cord is used as the reinforcing cord, and the cord angle is 90° with respect to the seven circumferential direction of the tie. I arranged it in two layers so that it would look like this.

Carcass layer side belt layer...1 x 5 as reinforcement cord
(0,:>5) steel cords were arranged in one layer so that the cord angle was 21° with respect to the tire circumferential direction.

Tread side belt layer...3 x 7 as reinforcement cord
(0,15) steel cords were arranged in one layer so that the cord angle was 24° with respect to the tire circumferential direction, and both left and right ends were bent toward the tread portion.

[Experimental Example 1] Using each of the tires described above, a vibration riding comfort performance test was conducted indoors using a protrusion tester.

The protrusion tester described above has a semicircular protrusion with a diameter of 20 mm placed at one location on the circumference of a drum with a diameter of 2500 tm.
The axial force in the longitudinal direction when the test tire passes over this protrusion is detected, and the magnitude of this axial force is used as a representative value of the vibration riding comfort performance.

<Test conditions> Air pressure...2.0 kg/c11° load...
...490 kg.

The speed is 601un/hr, 80km/h
Vibration ride comfort performance tests were conducted at speeds of 1,100 km/hr, and 120 km/hr.

The test results are shown in Figure 2. In addition, in FIG. 2, the test results of conventional tires are expressed as an index, with the test results set as 100.

As is clear from the test results shown in FIG. 2, it can be seen that the tire of the present invention has improved vibration riding comfort performance by about 10% compared to the conventional tire.

[Experimental Example 2] Using each of the tires described above, a high-speed performance test was conducted indoors using a drum tester (diameter: 1707 nm).

<Test conditions> Air pressure...3.0 kg/cI11° load...
...490 kg.

The speed is increased from 170 km/hr to 1Q km/hr every 10 minutes.
A high-speed performance test was conducted by stepping up the speed by hr and driving until the tires broke.

The test results are shown in Figure 3. In addition, FIG. 3 is shown as an index with the test results of conventional tires set as 100.

As is clear from the test results shown in FIG. 2, it can be seen that the tire of the present invention can improve high-speed performance by about 15% compared to the conventional tire.

〔Effect of the invention〕

As described above, in the present invention, a belt layer made of carbon fiber cords is arranged on the carcass side of the belt layer, and a heald layer made of aromatic polyamide fiber cords is arranged on the tread side, and further, Since the end of at least one layer of the tread side belt layer made of aromatic polyamide fiber cord is bent toward the tread side, high speed and riding comfort can be improved, and the weight of the tire can also be reduced. .

[Brief explanation of drawings]

FIGS. 1(a) to 1(d) show pneumatic radial tires for passenger cars according to embodiments of the present invention, and FIG. Figure (bl~
(dl is a partially cutaway explanatory diagram showing the main parts of the second to fourth embodiments, FIG. 2 is a diagram showing the results of a ride comfort test, and FIG. 3 is a diagram showing the results of a high speed test. 1...Bead part, 2...Side wall part, 3...
・Tread part, 4...Carcass layer, 5...Belt layer, 5d...Carcass layer α-rebelt layer, 5u...Tre throat side belt layer, C...Carbon fiber cord, P・・
・Aromatic polyamide fiber cord. - Sou @ cz ') Wisdom, fear, 1, time, Jg,

Claims (1)

[Claims] Consisting of a pair of left and right bead portions, a pair of left and right sidewall portions connected to the bead portions, and a tread portion located between the sidewall portions, the cord angle between the pair of left and right bead portions with respect to the tire circumferential direction is 70. A carcass layer having an angle of 10° to 90° is installed, and a cord angle of 10° to the tire circumferential direction is mounted on the carcass layer in the tread part.
In a pneumatic radial tire for a passenger car, which is formed by arranging a plurality of belt layers intersecting each other at an angle of 35° to 35°, a belt layer made of carbon fiber cord is arranged on the carcass side of the belt layers, and a tread part A passenger car, characterized in that a belt layer made of an aromatic polyamide fiber cord is arranged on the side, and an end of at least one layer of the tread side belt layer made of the aromatic polyamide fiber cord is bent toward the tread side. Pneumatic radial tire.