JP3053268B2 - Pneumatic tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire capable of reducing the weight of a tire without deteriorating running performance and reducing fuel consumption of a vehicle.

[0002]

2. Description of the Related Art In recent years, efforts have been made to promote energy saving, and there has been an increasing demand for reducing the weight of a vehicle body in order to reduce fuel consumption even in an automobile.

Conventionally, the weight of tires has been reduced mainly by the tread portion, which occupies the largest weight in the tire weight, particularly the belt layer. For example, an aromatic polyamide is used instead of steel for the cord of the belt layer. Tires using lightweight belt layers, such as those using tough organic fibers such as fibers, have appeared.

[0004]

When the cord of the belt layer is replaced with an aromatic polyamide fiber from steel as described above, the weight of the belt layer is greatly reduced, but the belt layer using a steel cord with a tread surface is used. As a result, there is a problem that the puncture resistance is poor and the steering stability is poor.

The inventor of the present invention has conducted intensive studies to solve the above-mentioned problems, and as a result, by arranging a belt ply using a steel cord at least for a portion occupying most of the tire contact surface, the puncture resistance has been improved. The present inventors have found that the performance and steering stability can be ensured and the weight of the belt layer can be reduced, and the present invention has been completed.

[0006] The present invention is based on the fact that the belt layer is formed by a belt ply using two aromatic polyamide fibers and a belt ply using one narrow steel cord. It is an object of the present invention to provide a pneumatic tire that can reduce the weight of a belt layer while maintaining steering stability, and can contribute to reducing fuel consumption of a vehicle.

[0007]

SUMMARY OF THE INVENTION The present invention provides a carcass comprising one or more carcass plies, which is turned around a bead core of a bead portion from a tread portion through a side wall portion, and a carcass comprising one or more carcass plies and a radial direction of the carcass. A pneumatic tire having a belt layer composed of three belt plies sequentially stacked on the outside, wherein two of the three belt plies have a first layer using an aromatic polyamide cord. The second aromatic polyamide cord ply is formed by a steel cord ply using a steel cord while the other belt ply is formed by the steel cord ply.
The deployment width, which is the width when the aromatic polyamide cord ply is deployed in the tire axial direction, is larger than the deployment width of the second aromatic polyamide cord ply, and the difference is 14 mm or less.
The spread width of the steel cord ply is greater than 0.4 times the spread width of the second aromatic polyamide cord ply and greater than 0.6 times the spread width of the second aromatic polyamide cord ply. The pneumatic tire is characterized in that the development width of the small, second aromatic polyamide cord ply is 0.7 times or more and 0.9 times or less the tire width.

It is desirable that the three belt plies are arranged in the order of a first aromatic polyamide cord ply, a second aromatic polyamide cord ply, and a steel cord ply from the carcass side to the radially outer side.

[0009]

The belt layer is composed of three belt plies, two of which are formed of an aromatic polyamide cord ply. Aromatic polyamide fiber cord has high tensile strength and tensile elasticity almost equivalent to steel cord,
The flexural rigidity of the tread portion can be maintained equal to the case where a steel cord is used. In addition, by employing an aromatic polyamide cord, the weight of the belt ply can be reduced to almost half as compared with a ply formed only of a steel cord, the tread portion can be reduced in weight, and the weight of the entire tire can be reduced.

[0010] Further, the deployment width of the second aromatic polyamide cord ply is regulated to be more than 0.7 times and less than 0.9 times the tire width. If the width is less than 0.7 times the width of the tire, the steering stability at high speeds is reduced. If the width is more than 0.9 times, both sides of the belt ply extend to the sidewalls and the rigidity of the sidewalls is increased, resulting in reduced ride comfort. Let it.

[0011] Further, the development width of the first aromatic polyamide cord ply is larger than the development width of the second aromatic polyamide cord ply, and the difference is 14 mm or less. If the difference between the deployment widths of both plies exceeds 14 mm, the steering stability will be greatly reduced. Moreover, if the difference in deployment width exceeds 15 mm,
The protruding margin of the end of the first aromatic polyamide cord ply becomes large, and the end of the first aromatic polyamide cord ply is repeatedly bent during running, so that peeling is apt to occur, thereby impairing durability.

[0012] Further, the development width of the steel cord ply is set to 0.4 to 0.1 of the development width of the second aromatic polyamide cord ply.
The range is 6 times. The deployment width of the steel cord ply is set to increase the rigidity of the tread surface, increase puncture resistance, and maintain steering stability by arranging the steel cord ply in the tread surface, especially at the position of the ground contact surface. is there. In addition, by using the steel cord ply, the shortage of the bending fatigue resistance, which is a weak point of the aromatic polyamide cord, can be compensated and the durability can be improved.

If it is less than 0.4 times, the area covered with the steel cord ply is omitted and the puncture resistance is inferior. On the other hand, if it exceeds 0.6 times, there is no improvement in steering stability corresponding to the increased width. Only weight increases. By setting the deployment width of the steel cord ply within the above range, the steel cord ply can increase the compressive rigidity of the aromatic polyamide cord and enhance the steering stability in cooperation with the two aromatic polyamide cord plies. .

Therefore, in the present invention, the weight of the belt layer can be reduced while maintaining the puncture resistance and the steering stability by organically integrating the structure.

[0015]

An embodiment of the present invention will be described below with reference to the drawings. 1 and 2, a pneumatic tire 1 includes a tread portion 2, a sidewall portion 3 extending inward in the tire radial direction from both ends thereof, and a bead portion 4 located at an inner end of the sidewall portion 3 in the tire radial direction. Further, the pneumatic tire 1 has a structure in which the carcass ply 6A is folded back from the tread portion 2 through the sidewall portion 3 around the bead core 5 of the bead portion 4, and one or more, in this embodiment, one carcass ply 6A. And a belt layer 7 composed of three belt plies 11, 12, and 13 which are sequentially stacked inside the tread portion 2 and radially outside the carcass 6.

In this embodiment, a bead apex 8 is set up in the bead portion 4 radially outward of the bead core 5 and between the main portion of the carcass 7 and the winding portion.

The carcass 6 is made of a carcass cord made of an organic fiber such as nylon, rayon, polyester, or aromatic polyamide fiber.
One or more radial or semi-radial carcass plies arranged at an angle of 90 ° are arranged, and in this example, one carcass ply is formed.

The belt layer 7 is composed of three belt plies 11, 12, and 13 as described above, and two of the three belt plies are made of the first aromatic ply 15 using an aromatic polyamide cord 15. The other belt ply is formed by a steel cord ply 13 using a steel cord 16 while being formed by the polyamide cord ply 11 and the second aromatic polyamide code ply 12.

In this embodiment, the three belt plies are arranged in the order of the first aromatic polyamide cord ply 11, the second aromatic polyamide cord ply 12, and the steel cord ply 13 from the carcass 6 side toward the outside in the radial direction. doing.

First aromatic polyamide cord ply 1
As shown in FIG. 2, the first and second aromatic polyamide cord plies 12 incline the respective aromatic polyamide cords 15 and 15 with respect to the tire equator C, and the first and second aromatic polyamide cord plies 11 and The two cords of the aromatic polyamide cord ply 12 exhibit a tag effect by being arranged in a direction crossing each other, and the tread portion 2
Increase rigidity.

Similarly, the steel cord ply 13 inclines the steel cord 16 with respect to the tire equator C and intersects with the cord of the second aromatic polyamide cord ply 12 located inside the steel cord ply 13 in the radial direction. It is arranged in the direction.

Next, the relationship between the width dimensions of each belt ply will be described. The width dimension, which is the length of each belt ply in the tire axial direction, is as shown in FIG.
1, 12, and 13 are regulated by the developed width which is the width when the tire is deployed in the tire axial direction.

First aromatic polyamide cord ply 11
Of the second aromatic polyamide cord ply 1
2 is larger than the developed width B2, and the width difference L is 14 mm.
On the other hand, the deployment width B2 of the second aromatic polyamide cord ply 12 is the tire width W which is the maximum width of the tire.
T is set to 0.7 times or more and 0.9 times or less.

Further, the development width B3 of the steel cord ply 13
Is 0.4 times or more of the development width B2 of the second aromatic polyamide cord ply 12 and 0.6 times or less of the development width B2.

Second aromatic polyamide cord ply 12
As described above, the development width B2 of the steel cord ply 1 is restricted to a certain range with respect to the tire width BW.
3, the steel cord ply 13 has a predetermined width having a small dimensional difference with respect to the second aromatic polyamide cord ply 12, so that the steel cord ply 13 has a tire contact surface S, as shown in FIG. Can cover almost the majority. Therefore, the steel cord ply 13 can reinforce the contact surface S which receives the highest pressure in the tread surface with the minimum required width, and is formed by the ply using the steel cord 16 having a large weight per unit area. The increase in the weight of the belt layer 7 is small, and the weight of the tire can be effectively reduced.

The three belt plies 11, 12, 13
Can be arbitrarily combined. For example, as shown in FIG. 3, a steel cord ply 13 is disposed between a first aromatic polyamide cord ply 11 and a second aromatic polyamide cord ply 12. And a first aromatic polyamide cord ply 11 as shown in FIG.
A steel cord ply 13 may be interposed between the steel cord ply and the carcass 6. However, as shown in FIG. 1, the first aromatic polyamide cord ply 11, the second aromatic polyamide cord ply 12, and the steel cord ply 13 are arranged in the order from the carcass 6 side to the outside, that is, from the one having the largest development width to the smallest. By overlapping, the accumulation of air inside the end of the belt ply during vulcanization of the tire was eliminated, cracks originating from the air accumulation were prevented, and the durability of the tread portion 2 could be further improved. .

[0027]

[Specific Examples] Tires (Examples 1 to 3) having a tire size of 225 / 50R16 and a belt layer 7 formed in the configuration shown in FIGS. Performance tested. FIG. 5 formed by two steel cord plies s1 and s2.
Conventional tire shown in (Comparative Example 1 ) , two polyamide tires
A test was also conducted on the tire formed by the dry ply (Comparative Example 2) to compare the performance.

[Table 1]

The test was performed under the following conditions. 1) Riding reaction force of a single projection Mount the sample tire on an 8JJ x 16 rim and 2.0kg
Attach internal pressure of f / cm ² and mount it on a test car.
The reaction force applied to the tire when the test vehicle climbs over a 10 mm × 10 mm timber placed on the road at a speed of 60 km / H under a load of 350 kgf per tire is determined by the gravitational acceleration G when the vehicle is climbed. It measured and the measured value was shown by the index | index which makes the comparative example 100. The smaller the numerical value, the smaller the riding reaction force and the better.

2) Cornering power Measured using a bench tester under the same rim and internal pressure as in 1). The speed is set at 10km / H,
The measured value was indicated by an index using Comparative Example 100. Numerical indicating that a large <br/> indeed good.

3) Weight of Belt Layer The weight was expressed as an index with the comparative example as 100. The smaller the value, the lighter the weight.

The performance of Examples 1 to 3 is intermediate between Comparative Examples 1 and 2.
(Single protrusion riding reaction force, cornering power) is located,
The performance differs depending on the position of the steel cord ply.
You. However, Examples 1-3 are from Comparative Example 1 (2 steel)
Achieved weight reduction and improved the performance of Comparative Example 2 (2 polyamide)
Supplements.

[0032]

As described above, the pneumatic tire of the present invention has the following features.
The belt layer is formed by laminating two aromatic polyamide cord plies and one steel cord ply, and regulates the development width of each belt ply. The development width of the polyamide cord ply is regulated. In particular, since the development width of the steel cord ply is set to 0.4 to 0.6 times the development width of the second aromatic polyamide cord ply, the steel cord ply is The tread portion is reinforced only at a minimum necessary portion, and can maintain running performance and reduce tire weight, which greatly contributes to energy saving of the vehicle, as compared with a conventional one formed only of steel cord plies.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention.

FIG. 2 is a developed plan view showing a belt ply of the belt layer.

FIG. 3 is a cross-sectional view showing another example of the superposition of the belt plies of the belt layer.

FIG. 4 is a cross-sectional view showing another example of the superposition of the belt plies of the belt layer.

FIG. 5 is a sectional view showing a belt layer of a conventional tire.

[Explanation of symbols]

 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 6A Carcass ply 7 Belt layer 11 First aromatic polyamide cord ply 12 Second aromatic polyamide cord ply 13 Steel cord ply 15 Aromatic polyamide cord 16 Steel cord B1 Deployment width of the first aromatic polyamide cord ply B2 Deployment width of the second aromatic polyamide cord ply B3 Deployment width of the steel cord ply WT Tire width

[Table 1]

Claims (2)

(57) [Claims] 1. A carcass comprising at least one carcass ply, which is turned around a bead core of a bead portion from a tread portion through a side wall portion, and three carcasses which are sequentially stacked inside the tread portion and radially outside the carcass. A pneumatic tire having a belt layer composed of a belt ply, wherein two of the three belt plies are a first and a second aromatic polyamide cord ply using an aromatic polyamide cord. The other belt ply is formed by a steel cord ply using a steel cord, and the first aromatic polyamide cord ply has a second aromatic The development width of the steel cord ply is larger than the development width of the polyamide cord ply and the difference is 14 mm or less. Aromatic polyamide cord ply of the deployment than 0.4 times the width of the large and the second aromatic polyamide cord ply the developing width of 0.6 times smaller than the,
Further, the pneumatic tire is characterized in that the deployment width of the second aromatic polyamide cord ply is 0.7 times or more and 0.9 times or less the tire width. 2. The three belt plies are arranged radially outward from the carcass side in the order of a first aromatic polyamide cord ply, a second aromatic polyamide cord ply, and a steel cord ply. The pneumatic tire according to claim 1, wherein