JP3405610B2 - Pneumatic radial 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 radial tire capable of improving lateral flow of a vehicle and enhancing straight running performance.

[0002]

2. Description of the Related Art With the recent improvement of vehicle performance and maintenance of road networks, tires are required to have a predetermined performance in addition to various performances such as durability, steering stability and riding comfort. While traveling a distance, it is desired to further improve the driving comfort such as shifting to one side with respect to the straight traveling direction line and causing lateral flow, reducing so-called vehicle lateral flow and improving straight running stability. There is.

Conventionally, the lateral flow of this vehicle is caused by what is called a conicity, which is a cone shape due to the difference in the circumferential length of the belt layer on the left and right in the tire axial direction of the tread portion. Various measures have been taken to increase the uniformity of the.

[0004]

However, it has been found that the improvement of the conicity cannot sufficiently prevent the lateral flow of the vehicle.

On the other hand, due to the recent progress in tire measurement technology, when a small slip angle is applied to the tire traveling direction, the cornering force generated in the tire lateral direction, that is, the lateral force and the vertical axis passing through the tire center Self-aligning torque (S
AT) and can be measured with high accuracy.

As a result of intensive studies conducted by the present inventor based on such measurement, the residual CF, which is the lateral force generated in the tire when the self-aligning torque is zero when the steering wheel is released, is reduced. Has been found to be effective in preventing lateral flow of the vehicle.

Further, as a result of various studies to reduce the residual CF, the present inventor has found that the residual CF greatly varies depending on the structure of the belt layer in addition to the tread pattern of the tire and the like.

That is, FIG. 3 shows only the belt layer a.
In a developed plan view of FIG. 1, a belt layer a conventionally used in a radial tire for a light truck, for example, has a belt cord made of steel, and a plurality of belt plies, for example, three belt plies, which are arranged inward and outward in the radial direction, are stacked. b1, b2,
b3 is provided, and the inclination of the belt cord of the inner belt ply b1 is increased to the right by 65 degrees with respect to the tire equator c.
The inclination of the belt cord of the intermediate belt ply b2 is upward to the left by 17 ° to the tire equator c, and the inclination of the belt cord of the outer belt ply b3 is upward to the right at 17 ° to the tire equator c, that is, 65 ° R / 17 ° L / 17 °
Although a triangle configuration with R is performed, the orientation of the outermost belt ply b3 in only one direction has an extremely large effect on the residual CF, and its value can be increased. I was able to find out.

Generally, when the residual CF is set to an extremely small value close to 0, although the lateral flow of the vehicle is greatly improved, the vehicle is apt to wobble when the steering wheel is released without self-aligning torque. It is also known that it is therefore desirable to equip the vehicle with tires having a small residual CF in a balanced manner, that is, in consideration of the lateral flow direction, in order to improve straight running stability.

The present invention is based on the fact that the outer belt ply is divided into two ply pieces in the tire axial direction and the belt cord of each ply piece is inclined in the opposite direction to the tire equator. CF remaining without compromising performance
It is an object of the present invention to provide a pneumatic radial tire that can reduce the vehicle lateral flow and improve the straight running performance by suppressing the lateral flow of the vehicle.

[0011]

The invention according to claim 1 of the present invention (the invention of the present application) is a carcass of a radial structure in which a tread portion passes through a sidewall portion and is folded back around a bead core of a bead portion, and inside the tread portion and 2-3 with steel belt cords on the outside of the carcass in the radial direction
And a belt layer in which the belt cords are overlapped with each other and the belt cords are inclined so as to be opposite to each other with respect to the tire equator, and the belt layer is
At least the outermost belt ply in the radial direction, and
The inner belt ply is divided into two in the tire axial direction.
By a pneumatic tire with two ply pieces each
is there.

Further, according to the present invention, the two ply pieces of the belt ply arranged on the outermost side in the radial direction have their belt cords oriented at an angle of 15 to 30 ° with respect to the tire equator, and at the same angle to each other. And the two ply pieces of the inner belt ply of the belt ply are arranged at an angle of 15 to 30 ° with respect to the tire equator, at the same angle in opposite directions, and at the outermost side. The ply piece of the belt ply to be tilted is also reversed.

Further, in the present invention, the two ply pieces of the belt ply arranged on the outermost side and the two ply pieces of the belt ply inside the outermost ply are the two ply pieces of each belt ply in the tire axial direction. Ply width WB
Width WA in the tire axial direction of the other ply piece with respect to
The ratio WA / WB of 3/7 or more and 0.95 or less, or 1.05 or more and 7/3 or less, and
The position is the same in the tire axial direction .

[0014]

[Function] 2-3 using a belt cord made of steel
The belt layer composed of one belt ply has at least the outermost belt ply in the radial direction in the tire axial direction.
It is divided into two ply pieces, and the belt cord of each ply piece is tilted in the opposite direction to the tire equator.
Therefore, since the inclination directions of the belt cords of the outer belt ply that have a great influence on the residual CF are oriented in opposite directions on the left and right, the residual CF caused by each ply piece is
As a result, the residual CF can be reduced,
The lateral flow of the vehicle can be effectively prevented and the straight running stability can be improved.

In the belt layer, at least the outermost belt ply is divided into two in the axial direction of the tire, but there is no change in that the belt cords intersect between the plies.
Therefore, various tire performances such as steering stability can be maintained.

Further, according to the present invention, the two ply pieces of the belt ply arranged on the outermost side in the radial direction have their belt cords oriented at an angle of 15 to 30 ° with respect to the tire equator, and opposite to each other at the same angle. And the two ply pieces of the inner belt ply of the belt ply are arranged at an angle of 15 to 30 ° with respect to the tire equator, at the same angle in opposite directions, and at the outermost side. The ply piece of the belt ply to be tilted is also reversed. As a result, when the belt cords of the two ply pieces are tilted at an angle of 15 ° or more and 30 ° or less with respect to the tire equator and at the same angle in opposite directions, the belt cords tilting in the same and opposite directions are used. , Residual C
F can be reduced more effectively.

If the angle is larger than 30 °, the hoop effect by the belt layer may be reduced and the steering stability may be impaired. On the other hand, if the angle is smaller than 15 °, the deformation of the belt layer may be difficult and the tire strength may be reduced. Lower.

Further, in the present invention, the two belt plies arranged on the outermost sides of the two ply pieces and the belt ply on the inner side of the two ply pieces are the other with respect to the ply width WB of one ply piece in the tire axial direction. The ratio WA / WB of the ply width WA in the tire axial direction of the ply piece is 3/7 or more and 0.95 or less, or 1.05 or more and 7/3
Since the divided positions are set to the same position in the tire axial direction below, it is possible to suppress an excessive decrease in the residual CF and prevent the running vehicle from wobbling.

If the ratio WA / WB is smaller than 3/7, the effect of reducing the residual CF cannot be sufficiently achieved. Again 1
The residual CF becomes smaller as the value approaches to, but the excessive decrease is not so preferable from the viewpoint of the vehicle wobbling as described above, and therefore the ratio WA / WB is more preferably 3/7.
Or more and 0.95 or less, or 1.05 or more and 7 /
It is better to be 3 or less.

Further, in the invention of claim 2 , the inner belt ply adjacent to the carcass of the belt layer consisting of three belt plies is formed from one ply piece continuous in the tire axial direction, and the belt cord is formed. When tilted at an angle of 60 ° or more and 68 ° or less with respect to the tire equator, the divided belt plies can be reliably reinforced on the outside of the carcass by one ply piece, and the tire strength can be maintained.

If the angle is larger than 68 °, the lateral rigidity, especially in the tire axial direction, may become excessively large, which may deteriorate the steering stability. On the other hand, if it is smaller than 60 °, the tire rigidity tends to be insufficient. Will reduce the tire strength.

As described above, according to the present invention, since the above-mentioned constitutions are organically and integrally combined, the residual CF can be appropriately reduced without impairing the steering stability and the tire strength, and the lateral flow of the vehicle can be prevented. Therefore, straight running stability can be improved.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 and 2, a pneumatic radial tire 1 of the present invention includes a carcass 6 which is folded from a tread portion 2 to sidewall portions 3 and 3 and around a bead core 5 of a bead portion 4 from an inner side to an outer side in a tire axial direction, A belt layer 7 disposed inside the tread portion 2 and outside the carcass 6 in the radial direction.

The carcass 6 is a radial or semi-carcass in which carcass cords made of organic fibers such as nylon, rayon, polyester and aromatic polyamide fibers are arranged at an angle of 70 to 90 ° in this example with respect to the tire equator C. The carcass plies 6A and 6B are one or more in a radial arrangement, in this example, two.

The belt layer 7 is formed by stacking two to three, in this example, three belt plies 7A, 7B and 7C from the carcass 6 side toward the tread surface 2A. The belt plies 7A, 7B and 7C are formed by cut plies in which an array of belt cords 9A, 9B and 9C made of steel is covered with rubber.

The inner belt ply 7A adjacent to the carcass 6 is a single ply piece 1 continuous in the tire axial direction.
2 and its belt cord 9A ... at tire equator C
In the developed plan view of FIG. 2, they are arranged in an upward direction at an inclination angle α of 60 to 68 °.

Further, the belt ply 7C arranged on the outermost side in the radial direction is divided into two in the tire axial direction by one tire circumferential line L, so that two ply pieces 10A, 10 are formed.
B, and the ratio WA / WB of the ply width WA in the tire axial direction of the other ply piece 10B to the ply width WB in the tire axial direction of one ply piece 10A is 0.95 to
3/7 (7/3 to 1.05), which is 3/7 in this embodiment.

Therefore, the tire circumferential direction line L on which the ply pieces 10A and 10B contact each other is, as shown in FIG.
Located to the left of.

Further, the belt cords 9Ca and 9Cb of the ply pieces 10A and 10B are 15 to 15 degrees with respect to the tire equator C.
At an inclination angle of 30 ° (β1, β2), and at the same angle, but in the opposite direction, in this embodiment, the belt cord 9Ca of the ply piece 10A is moved to the left and the belt cord 9Cb of the ply piece 10B is moved to the right in FIG. Are arranged.

Further, the intermediate belt ply 7B (inner belt ply of the outermost belt ply C) is divided into two in the tire axial direction at the tire circumferential direction line L, similarly to the belt ply 7C. One ply piece 11
A and 11B, and each ply piece 11A, 11
The belt cords 9Ba and 9Bb of B are 15 to 30 ° with respect to the tire equator C, and in the present example, the belt cords 9Ca and 9 have the same inclination angles γ1 and γ2 as the inclination angles β1 and β2.
The belt cords are arranged so as to intersect with Cb, that is, in the direction opposite to the ply piece of the outermost belt ply 7C as shown in FIG. Thus, the intermediate belt ply 7B
Is also divided by the tire circumferential line L, and the outermost bell
The split position of Topry 7C should be the same position in the tire axial direction.
It

Since the intermediate belt ply 7B is configured as described above, the increase of the residual CF can be suppressed more effectively by the orientation of the belt cords 9B and 9C, and
Belt cords 9Ba, 9Ca and 9Bb, 9C intersecting
Since b is inclined at the same inclination angles β1, γ1, β2, γ2, it is possible to effectively exhibit the hoop effect, improve the strength balance of the tire, and maintain the steering stability.

[0032]

SPECIFIC EXAMPLE Regarding tires having a tire size of 215SR15, tires (Examples 1 to 4) having a belt layer according to the configuration of the present application were prototyped based on the specifications of Table 1, and the residual CF, steering stability, tire The strength was investigated. The tires (Comparative Examples 1 and 2) formed of the belt layer having the conventional structure were also investigated and their performances were compared.

[0033]

[Table 1]

The residual CF is 15 × 6-JJ on the tire.
Mounted on the rim of the car and loaded with 2.0 kgf / cm ² of internal pressure, 5
The lateral force when the self-aligning torque measured by a flat belt type tester becomes 0 when a load of 00 kgf is applied is shown.

The steering stability was indicated by an index with Comparative Example 1 being 100, based on a sensory evaluation by a lane change and a circle turning test of an actual vehicle running on a dry asphalt road surface. The larger the value, the better.

The tire strength, as defined by JIS D-4230, is the energy leading to the destruction of the tire, and a hemispherical-shaped blanker (diameter 19φ) is perpendicular to the tire axis at 50.0 / min. The strength was measured by pressing at a speed of ± 2.5 mm, and Comparative Example 1 was
It is indicated by an index of 00. The larger the value, the better.

Here, W is the breaking energy (kgf · cm) F is the pushing force at the time of breaking (kgf · cm) P is the moving amount of the blanker (mm) W = (F × P) / 2 The breaking energy W was calculated by this formula.

As a result of the test, it was confirmed that in the example, the residual CF was reduced while maintaining the steering stability and the tire strength.

[0039]

INDUSTRIAL APPLICABILITY As described above, the pneumatic radial tire of the present invention uses a belt cord made of steel for 2-3.
A belt ply, which is arranged at least on the outermost side in the radial direction of a belt layer composed of a number of belt plies, is divided into two ply pieces in the tire axial direction, and the belt cord of each ply piece is oriented in the opposite direction to the tire equator. I'm leaning. Therefore, since the inclination directions of the belt cords of the outer belt ply, which have a great influence on the residual CF, are oriented in the opposite directions on the left and right, the residual CF caused by each ply piece can be offset, and the residual CF can be reduced. As a result, the lateral flow of the vehicle can be effectively prevented and the straight running stability can be improved.

In the belt layer, at least the outermost belt ply is divided into two in the tire axial direction, but there is no change in that the belt cords intersect between the plies.
Therefore, various tire performances such as steering stability can be maintained.

[0041] Further, the respective belt cords of the two plies pieces 15 ° or more and 30 ° or less an angle with respect to the tire equator, yet when tilted in opposite directions at the same angle to each other, inclined to the same and opposite Residual C due to belt code
F can be reduced more effectively.

Further, the ratio WA / WB of the ply widths of the two divided ply pieces can be set to suppress the excessive reduction of the residual CF, and to prevent the vehicle from wandering while running.

At this time, the ratio WA / WB is set to 3/7 or more and 0.95 or less, or 1.05 or more and 7/3 or less .

Further, in the invention of claim 2, the inner belt ply adjacent to the carcass of the belt layer composed of three belt plies is formed from one ply piece continuous in the tire axial direction, and the belt cord is formed. When tilted at an angle of 60 ° or more and 68 ° or less with respect to the tire equator, the divided belt plies can be reliably reinforced on the outside of the carcass by one ply piece, and the tire strength can be maintained.

As described above, according to the present invention, since the above-mentioned constitutions are organically and integrally combined, the residual C can be maintained without impairing various tire performances such as steering stability and tire strength.
F can be reduced appropriately, lateral flow of the vehicle can be prevented, and straight running stability can be improved.

[Brief description of drawings]

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

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

FIG. 3 is a developed plan view showing a configuration of a conventional belt layer.

FIG. 4 is a developed plan view showing a configuration of a belt layer of Comparative Example 2.

[Explanation of symbols]

2 tread part 3 sidewall part 4 bead part 5 bead core 6 carcass 7 belt layers 7A, 7B, 7C belt plies 9A, 9B, 9Ba, 9Bb, 9C, 9Ca, 9Cb
Belt cord 10A, 10B Ply piece 12 Ply piece C Tire equator

─────────────────────────────────────────────────── --Continued from the front page (56) Reference JP-A-4-163210 (JP, A) JP-A-3-121906 (JP, A) JP-A-61-81204 (JP, A) JP-A-3- 344719 (JP, A) JP-A 1-148604 (JP, A) JP-A 6-16009 (JP, A) JP-A 6-156015 (JP, A) Actual development Sho 61-24203 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B60C 9 / 18,9 / 20,9 / 30

Claims (2)

(57) [Claims] 1. A carcass having a radial structure which folds from a tread part through a sidewall part and around a bead core of a bead part, and a belt cord made of steel 2-3 inside the tread part and radially outside the carcass. A belt layer in which a plurality of belt plies are superposed and belt cords between the plies are inclined so as to be opposite to each other with respect to the tire equator, and the belt layers are arranged at least on the outermost side in the radial direction. belt plies and belt plies of the inner, as well as having each two ply pieces by being divided into two in the tire axial direction, and the two ply piece of belt plies disposed radially outermost, the belt 15 cords to tire equator
The two ply pieces of the inner belt ply have their belt cords at an angle of 15 to 30 ° with respect to the tire equator, while being inclined in the opposite directions at an angle of -30 ° and at the same angle. in opposite directions at the same angle to each other, yet the causes are inclined in opposite with ply piece of belt plies disposed on the outermost side, two ply pieces of the belt ply disposed on the outermost side,
And two ply pieces of the inner belt ply, each base
In the rut ply, the ratio WA / WB of the ply width WA in the tire axial direction of the other ply piece to the ply width WB in the tire axial direction of the other ply piece is 3/7 or more and 0.95 or more.
The pneumatic radial tire is characterized in that it is equal to or less than 1.05 and equal to or less than 7/3, and the division positions are the same in the tire axial direction . 2. The belt layer comprises three belt plies, and the inner belt ply adjacent to the carcass has a belt cord of 60 to 68 with respect to the tire equator.
The pneumatic radial tire according to claim 1 , wherein the pneumatic radial tire comprises one ply piece inclined at an angle of ° and continuous in the tire axial direction.