JPH05330308A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To provide a pneumatic tire capable of lightening tire weight and also improving a ride comfortableness, by forming a carcass and a belt through using a high strength fiber having low flexural rigidity and large elongation compared with steel. CONSTITUTION:A pneumatic tire 1 is composed with an anular tread part 2, a side wall 3, a bead part 4, a carcass layer 6, bead apexes 7, and a belt layer 8. The carcass layer is formed with a carcass ply using a composite cord of an aromatic polyamide fiber and a nylon fiber; the belt layer is formed by overlapping two belts composed of plural plies in which plural high strength fiber cords are arranged in parallel; belt strength FNP/5cm per unit width is made a range of 5,000-6,500kg/5cm; the number of overlapped belt plies is made 2-4; and the maximum width of the belt layer 8 is formed 0.8-0.9 time of tread width.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an annular tread portion,
A pair of sidewalls extending in the tire radial direction from both ends of the tread portion, a pair of bead portions provided at the sidewall ends and engaging with the rim, and penetrating the tread portion and the sidewalls and locked to the bead portion. The present invention relates to a pneumatic tire having a carcass layer and a belt layer arranged in the tread portion on the outer side in the tire radial direction of the carcass layer, and particularly to a pneumatic tire used under conditions of high internal pressure and high load.

[0002]

2. Description of the Related Art Recently, radial tires are required to have low fuel consumption performance, long life performance (durability performance) and steering stability performance.
It has become a mainstream of pneumatic tires to be used because it has far superior performance to bias tires.

Such a pneumatic tire (radial tire) has an annular tread portion, a pair of sidewalls extending in the tire radial direction from both ends of the tread portion, and a pair of sidewalls provided at the sidewall ends to engage with the rim. A bead portion, a carcass layer composed of cords having both ends locked to the bead portion, arranged in the tire radial direction, and extending through both sidewall portions and the tread portion, and arranged on the tire radial direction outer side of the carcass layer. It has a high-rigidity belt layer made of steel or the like.

[0004]

Generally, the carcass of a radial tire, which is required to have high steering stability, is made of organic fibers, steel cords, etc., and is composed of two plies (particularly organic fiber cords) to increase lateral rigidity. And the belt is made of steel. In recent years, there have been severe demands for weight reduction of tires due to low fuel consumption of vehicles.
If the ply carcass is changed to a one ply carcass, a considerable amount of weight reduction of the tire can be achieved, but at the same time, steering stability, especially turning performance is deteriorated due to the decrease in lateral rigidity.
Also, in order to reduce the weight of the belt layer, if a belt is formed by using a high-strength fiber that is lighter and has a lower strength than steel, for example, an aromatic polyamide fiber, it has the same end number (strike number) and the same overlap as the steel belt. If it is formed with the number of combined sheets, the tire strength (breaking strength by the plunger test) will be insufficient for pneumatic tires used at high internal pressure, such as small truck tires, and the number of laminated sheets must be increased, resulting in an increase in weight. And the ride quality deteriorates. Furthermore, when an aromatic polyamide fiber cord having the same strength as the steel cord is used, the cord diameter becomes large, and the cord is apt to be broken.

An object of the present invention is to reduce the tire weight and improve the riding comfort by forming a carcass and a belt by using a high-strength fiber having a low bending rigidity and a large elongation as compared with steel. It is to provide a pneumatic tire that can be used.

[0006]

A pneumatic tire according to the present invention is provided with an annular tread portion, a pair of sidewalls extending in the tire radial direction from both ends of the tread portion, and sidewall beads provided with bead cores embedded therein. A pair of bead parts, a carcass layer having carcass plies extending at both ends folded back around a bead core and wound up and arranged in the tire radial direction, and penetrating both sidewall parts and a tread part, and a carcass layer tire In a pneumatic tire having a belt layer arranged radially outside,
The carcass layer is formed by one carcass ply composed of a composite cord of aromatic polyamide fiber and nylon fiber, and the belt layer is formed by stacking belt plies using a high-strength fiber cord. The belt strength, which is the product of the number, the cord strength, and the number of plies, is 5,00.
0 to 6,500 kg / 5 cm, the number of belt plies to be overlapped is 2 to 4, and the maximum width of the belt layer is 0.
It is formed in the range of 8 to 0.9 times, and it is possible to reduce the weight of the tire, secure the tire strength and durability, and improve the riding comfort.

[0007]

1 is a sectional view of a pneumatic tire to which the present invention is applied in a tire width direction. A pneumatic tire 1 includes an annular tread portion 2 and a pair of sides extending in the tire radial direction from both ends of the tread portion 2. Wall 3 and sidewall 3
A pair of bead portions 4 provided at the inner ends in the radial direction of the tire, in which an annular bead core 5 is embedded, and both ends folded back around the bead core 5 and penetrating both sidewalls 3 and the tread portion 2, and a tire radius. Carcass layer 6 arranged in the direction
And a JISA hardness of 70-having a tapered shape upward
A bead apex 7 made of hard rubber of 90 degrees and arranged on the outer side of the bead core 5 in the tire radial direction, and a belt layer 8 arranged on the outer periphery of the carcass layer 6 in the tire radial direction.

The carcass layer 6 uses a composite cord composed of aromatic polyamide fiber and nylon fiber as a high-strength fiber cord having a strength of 30 kg or more per cord.
It is formed of a sheet of carcass ply, and both ends are wound around the bead core 5 from the tire inside to the outside.

The belt layer 8 has a plurality of plies in which a plurality of high-strength fiber cords, that is, high-strength fiber cords (aromatic polyamide fiber cords in this embodiment) having a strength of 30 kg or more per cord are arranged in parallel. It is formed of two sheets in FIG. 1.

The belt layer 8 has a belt strength FNP represented by the product of the number of ends N, the cord strength F, and the number of plies P per 5 cm width of 5,000 to 6,500 kg / 5 cm, and the maximum width of the belt is tread width. 0.8 to 0.9 times the number of plies and the number of plies to be overlapped is 2 to 4. This is because when the maximum width (WB) of the belt layer 8 is less than 0.8 times the tread width (WT), the rigidity at both side edges of the tread becomes low,
Induces uneven wear. On the other hand, if it exceeds 0.9 times, the end of the belt ply will be located close to the end of the tread where the movement is the most vigorous, which will be the starting point of the ply loose. That is, by setting the maximum width of the belt layer 8 within the range of 0.8 to 0.9 times the tread width, uneven wear of the tread is less likely to occur, and peeling of the belt ply is prevented to improve durability.

Next, Tables 1 and 2 below show experimental results of tires to which the present invention is applied and tires having other structures. The conventional example is a tire having a conventional structure, which includes a carcass layer in which two polyester fiber cords are superposed and a belt layer formed of two steel belts. Examples 1, 2,
3 is a tire to which the present invention is applied, which is a belt layer formed by stacking a plurality of 1-ply carcass layers made of a composite cord of aromatic polyamide fiber and nylon fiber and a belt made of an aromatic polyamide fiber cord. It is equipped with and. In Comparative Example 1, a one-ply carcass layer composed of a composite cord of aromatic polyamide fiber and nylon fiber, and an aromatic polyamide fiber cord was used. More than twice the number of laminated sheets (6 sheets) is provided and the belt layer is provided.

In Tables 1 and 2, the rolled-up structure is shown. For example, in the 2-0 structure, the first number 2, which is the number of carcass plies, passes from the inside to the bottom of the bead core and is wound outside. The number of inner plies is shown. Further, the next numeral 0 indicates the number of plies (outer plies) that pass from the outside below the bead core and are wound inside. In addition, the tire size of each of the above tires is 195 / 70R17.5, the tire weight and the belt strength are shown in parentheses with the index of the conventional example being 100, and the durability and riding comfort are 100 of the conventional example. It is indicated by an index.

[0013]

[Table 1] Conventional example Comparative example 1 Carcass 2 / 1500d (PE) 2000dk / 1680dN (* 1) Winding structure 2-0 1-0 Belt cord material Steel Aromatic polyamide Fineness 1 × 3 / .175 + 6 / .32 2 / 1500d End number N (this / 5cm) 26 26 Number of belt plies P 2 6 Belt maximum width / tread width 0.80 0.78 Tire weight 100 102 Belt strength FNP / 5cm 7,020 4,770 Durability 100 95 Ride comfort 100 115 115 Uneven wear resistance 100 95 (the following margin)

[0014]

[Table 2] Example 1 Example 2 Example 3 Carcass 2000dk / 1680dN (* 1) ← ← Winding structure 1-0 ← ← ← Belt cord material Aromatic polyamide ← ← Fineness 2 / 1500d 2 / 3000d 3 / 3000d End number N (book / 5cm) 35 35 29 Number of belt plies P 4 2 2 Belt maximum width / tread width 0.80 0.90 0.95 Tire weight 97 91 93 Belt strength FNP / 5cm 6,500 5,000 6,500 Durability 110 100 95 95 Ride comfort 110 115 105 Uneven wear resistance 100 100 100 100 In the above Tables 1 and 2, (* 1) indicates that one strand of 2000d made of aromatic polyamide fiber filament and one strand of 1680d made of nylon fiber filament are twisted together. Shows a composite code consisting of:

As is clear from Tables 1 and 2, the pneumatic tires (Examples 1 to 3) to which the present invention is applied
The tire with more than four belt plies forming the belt layer (see Comparative Example 1) has a belt strength of less than 5,000 kg / 5 cm and a steel belt. Compared with the tire used (see the conventional example), the weight of the tire increases and the durability deteriorates.
So far, only the fiber using aromatic polyamide fiber as the high-strength fiber has been described, but it goes without saying that the high-strength fiber is not limited to the aromatic polyamide fiber.

[0016]

Since the present invention is configured as described above, it has the following effects. The carcass can be formed with one carcass ply using high-strength fiber to reduce the tire weight, and a belt is also formed using high-strength fiber to form a belt layer. By reducing the number of belts to less than twice the number of used tires and making the belt strength 70% to 90% of the steel belt, the tire weight can be reduced, the tire strength and durability can be secured, and the riding comfort is improved. Can be made Further, by setting the maximum width of the belt within the range of 0.8 to 0.9 times the tread width, uneven wear of the tread is less likely to occur, and peeling of the belt ply is prevented to improve durability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view in a width direction of a radial tire to which the present invention has been applied.

[Explanation of symbols]

 1 Radial tire 2 Tread part 3 Sidewall part 4 Bead part 5 Bead core 6 Carcass layer 7 Bead apex 8 Belt layer 9 Rubber layer

Claims (1)

[Claims] 1. An annular tread portion, a pair of sidewalls, a pair of bead portions in which a bead core is embedded, and both ends are folded back around the bead core and wound up to be arranged in the tire radial direction. In a pneumatic tire including a carcass layer formed of a carcass ply extending through the tread portion and a tread portion, and a belt layer arranged on the tire radial outside of the carcass layer, the carcass layer is composed of an aromatic polyamide fiber and a nylon fiber. The carcass ply is made of a composite cord, and the belt layer is formed by stacking belt plies using high-strength fiber cords, which is the product of the number of ends, the cord strength, and the number of plies. Belt strength from 5,000 to 6,500 kg
Pneumatic tire characterized in that the maximum width of the belt layer is formed in a range of 0.8 to 0.9 times the tread width, and the belt ply has a number of overlapping layers of 2 to 4.