JPH05139115A - Heavy duty pneumatic tire - Google Patents

Abstract

PURPOSE:To allow the durability on a rough road to be compatible with the durability on a smooth road by inclining belt layer cords on the narrow belt layer side to the equatorial plane at a tilt angle theta1 between the equatorial face and the belt layer end, thereafter bending the belt layer cords to a specified face parallel to the equatorial face at a tilt angle theta2, and making the tilt angle theta1 larger than the tilt angle theta2. CONSTITUTION:Belt layer cords on the narrow belt layer side out of a pair of crossing layers, namely the belt layers 2B, 3B are inclined to the equatorial plan at a tilt angle theta1 between the equatorial plane and the belt layer end, and then bent to a specified face parallel to the equatorial plane at a tilt angle theta2. The respective tilt angles theta1, theta2 of the cords are expressed by: 18 deg.<=theta1<=35 deg., 10 deg.<=theta2<=25 deg. thus, since the tile angle theta1 is constantly larger than the tilt angle theta2, the durability on a smooth road during high speed travel is not reduced, and the durability on a rough road can be compatible with the durability on a smooth road.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heavy-duty radial tire belt structure which has both good road durability and good road durability.

[0002]

2. Description of the Related Art Steel belts of conventional radial tire belts are generally arranged linearly. In addition, increasing the angle of the intersecting layer with respect to the equatorial plane is effective in improving the durability of the tire on rough roads, and lowering the tension applied to the steel cord is also effective in improving the enveloping property. On the other hand, it is generally effective to reduce the angle of the intersection angle with respect to the equatorial plane, increase the tension applied to the steel cord, and suppress diameter growth and running growth in order to improve good road durability. Are known.

[0003]

By the way, when the belt angle of the intersecting layer is changed in the belt structure of such a tire, good road performance and bad road performance are in conflict with each other. That is, when the angle with respect to the equator surface is increased, the belt rigidity is reduced, and the tire's enveloping power and the deformation distortion of the tire on a bad road surface are reduced.
Although the cut resistance and the separation when stepping on the protrusion are improved, the deformation and running growth of the belt at the time of side force input on a good road become large, and the problem that the high speed high-speed durability is deteriorated is a problem. there were.

The present invention was devised to solve the above-mentioned problems, and it is an object of the present invention to provide a heavy-duty radial tire having a belt structure which has both poor road durability and good road durability. To aim.

[0005]

In order to achieve the above object, in the heavy duty radial tire of the present invention, the tread portion of the tire comprises a cord extending at an angle of substantially 90 ° with respect to the circumferential direction of the tire. In a radial tire provided with a carcass layer and a belt layer that is arranged radially outward in the crown area of this carcass layer and that includes at least one pair of intersecting layers formed of cords that intersect with each other, Among them, the belt layer cord on the narrow side is inclined at an inclination angle θ ₁ with respect to the equatorial plane between the equatorial plane and the end of the belt layer, and then is inclined with respect to a predetermined plane parallel to the equatorial plane at an inclination angle θ _2. Bend at, and the inclination angle θ of each of the cords
₁ and θ ₂ have a relationship of θ ₁ > θ ₂ , and of the pair of intersecting belt layers in the above tire, the belt layer cord on the narrow side is connected to the equatorial plane and the belt layer end. Between the equatorial planes at an inclination angle θ ₁ and then bent at an inclination angle θ ₂ with respect to a predetermined plane parallel to the equatorial plane, and the respective inclination angles θ ₁ and θ _{2 of the} cord are , Θ ₁ > θ ₂ , 1
8 ° ≦ θ ₁ ≦ 35 °, 10 ° ≦ θ ₂ ≦ 25 °, and among the belt layers forming the pair of intersecting layers in the tire, the belt layer cord on the narrow side is Inclination angle θ _{1 with} respect to the equatorial plane between the equatorial plane and the belt layer edge
, And then bend at a slant surface θ ₂ with respect to a predetermined plane parallel to the equatorial plane, and each slant angle θ _{1 of} the cord,
θ ₂ has a relationship of θ ₁ > θ ₂ , and the width w from the equatorial plane to a predetermined plane parallel to the equatorial plane forming the angle at which the cord is bent at the inclination angle θ ₂ and the belt layer from the equatorial plane. The relationship between the width W to the edge is 0.2 W ≦ w ≦ 0.6 W, respectively.

[0006]

[Function] By changing the so-called central part cord angle from the equatorial plane of the crossing layer of the belt structure to a predetermined plane parallel to the equatorial plane and the so-called shoulder cord angle from the predetermined plane parallel to the equatorial plane to the belt end By lowering the belt tension in the central part and raising the tension in the shoulder part, the rigidity of the central part of the belt, which has a high cut damage rate, is reduced to ensure the enveloping property, which is useful for running growth and belt deformation during side force operation. The contributing shoulders increase the rigidity of the belt and suppress its deformation. In this case, the strain is larger in the layer on the narrower side of the two intersecting layers, so that particular attention is paid to that point.

In the above relation, the number of cuts reached is measured for a bad road, and the separation at the end of the belt is measured for a good road. The belt inclination angle θ for the envelopability E _p and the good road durability is measured. If you look at the relationship between, E _p and the inclination angle θ is small, well, show the E _p becomes worse trend in accordance with the inclination angle is increased. On the other hand, as for the good road durability, according to the result of measuring the occurrence of the separation at the belt end, the good road durability is poor when the cord inclination angle of the belt is close to 0 °, and becomes good as it increases. As for the angle at which the both are compatible, the range of the inclination angle θ of 15 ° ≦ θ ≦ 35 ° is suitable for the E _p property, and the inclination angle θ of 10 ° ≦ θ ≦ 25 ° is suitable for the good road durability. The range was found to be suitable.

Further, the cord angle at the shoulder portion is made smaller to raise the cord to secure a distance between the cord at the belt end and the cord, whereby a crack at the cord end is connected between the cords. Since there is no such thing, the progress toward separation can be delayed.

[0009]

EXAMPLES Examples will be described with reference to the drawings. According to the tire belt structure shown in FIG. 1, tire size 1
A 1R22.5 pneumatic radial tire was prototyped. The belt structure in the tread portion 1 is composed of four belt layers, which are layers 1B, 2B, 3B, and 4B sequentially from the innermost layer, and are arranged symmetrically with respect to the equatorial plane. The innermost layer 1B has a hollow structure and is disposed on the carcass 2 with a certain distance from the equatorial plane. The width is 55 mm, and the cord angle is the inclination angle θ _{1B with} respect to the equatorial plane. It is 52 ° on the right. The belt layer 2B has a width of 200 mm and is located on the upper right side, and the inclination angle θ _2B is also 22 °. The belt layer 3B has a width 2W of 180 mm, its cord is at the upper left, and the inclination angle θ _3B1 is 22 ° in the range of the width w = 35 mm from the equatorial plane, and the range from the outside to the belt end, that is, the shoulder portion. θ _3B2 is 16 °.
Further, the belt layer 4B has a width of 110 mm, the cord is inclined to the upper left, and the cord inclination angle θ _4B is 18 °. The test tire has a belt structure having the above structure and dimensions. Therefore, the angle of inclination of the cords of the test tires and belts with respect to the equatorial plane was 16 ° and 2
For 3 tires of 2 °, the actual vehicle test was
5 under the condition of load 2.8 ton and internal pressure 7.25 kg / cm ^2.
After running 10,000 km, the following results were obtained. Tables 1 and 2 show the results of the evaluation of these test tires.

[0010]

[0011]

(Note) The cord inclination angles of 16 ° and 22 ° indicate the inclination angles with respect to the equatorial plane. In the present invention, the belt layer 3B is used.
The cord inclination angle with respect to the equatorial plane at the center of is 22
Shows the case where the cord inclination angle at the shoulder portion is 16 °. As can be seen from the two comparison results, the inclination angle of the belt cord in the belt layer 3B is 22 ° in the central portion and 1 in the shoulder portion as in the present invention.
It was revealed that the test tire of the example having the belt structure in which the cord was bent so that the angle was 6 ° had good envelopeing property and crack resistance at the belt end portion, and consequently good durability. ..

[0013]

As described above, a carcass layer formed of a cord extending at an angle of substantially 90 ° with respect to the circumferential direction of the tire is provided in the tire tread portion, and the carcass layer is arranged radially outward in the crown region of the carcass layer. , In a heavy duty pneumatic radial tire having at least one pair of intersecting belt layers composed of cords intersecting each other, among the pair of intersecting belt layers, the belt layer cord on the narrow side is an equatorial plane. Angle of inclination θ _{1 with} respect to the equatorial plane at the belt layer end
And then bend at a slope θ ₂ with respect to a predetermined plane parallel to the equatorial plane, and the relationship between the inclination angles θ ₁ and θ ₂ of the cord is such that θ ₁ and θ _{2 are} larger than θ _2. In the above tire, the relation between the inclination angles θ ₁ and θ ₂ of the cords is θ ₁ > θ ₂ , 18 ° ≦ θ ₁ ≦ 35 °, 10 ° ≦ θ ₂
≦ 25 °, and in the same tire, the relationship between the inclination angles θ ₁ and θ ₂ of the cords is θ.
₁ > θ ₂ and the cord has an inclination angle θ from the equatorial plane.
The relationship between the width w from the equatorial plane to the end of the belt layer and the width W to a predetermined plane parallel to the equatorial plane forming an angle of ₂ is 0.2.
Since it is configured to satisfy W ≦ w ≦ 0.6W, the tire enveloping power and the deformation distortion of the tire on a bad road surface are appropriately small. Therefore, the cut resistance, the separation when stepping on the protrusions, etc. are moderate. On the other hand, on the other hand, it is possible to considerably suppress the deformation and running growth of the belt at the time of inputting the side force on the good road, and as a result, the high-speed durability on the good road does not decrease, and the durability performance on the bad road and the good road It is possible to provide a tire suitable for heavy loads such as for trucks and construction vehicles as well as for trucks.

[Brief description of drawings]

FIG. 1 is a plan view showing a belt structure of a tread portion of a tire of the present invention.

FIG. 2 is a sectional view showing a belt structure of a tread portion of a tire of the present invention.

FIG. 3 is a plan view of belt layers 2B and 3B of the belt structure of the tire of the present invention.

[Explanation of symbols]

1 tread part 2 carcass 1B innermost belt layer 2B second from the bottom belt layer 3B third from the bottom belt layer 4B outermost belt layer θ _1B angle formed with equatorial plane of belt layer 1B θ _2B belt layer Angle formed with the equatorial plane of 2B θ _3B1 Angle formed with the equatorial plane of the belt layer 3B θ _3B2 Angle formed with faces separated by a predetermined width parallel to the equatorial plane of the belt layer 3B θ _4B Angle formed with the equatorial plane of the belt layer 4B

Claims (3)

[Claims] 1. A carcass layer, which comprises cords extending at an angle of substantially 90 ° with respect to the circumferential direction of the tire in the tread portion of the tire, and is arranged radially outward in the crown region of the carcass layer and intersects with each other. In a radial tire provided with a belt layer forming at least a pair of intersecting layers made of cords, among the belt layers forming the pair of intersecting layers,
The belt layer cord on the narrow side is inclined at an inclination angle θ ₁ with respect to the equatorial plane between the equatorial plane and the belt layer end, and then bent at an inclination angle θ ₂ with respect to a predetermined plane parallel to the equatorial plane. However, the pneumatic tires for heavy loads are characterized in that the respective inclination angles θ ₁ and θ _{2 of the} cord have a relationship of θ ₁ > θ ₂ . 2. The respective inclination angles θ ₁ and θ _{2 of the} cord are:
The heavy-duty pneumatic tire according to claim 1, which has a relationship of 18 ° ≤ θ ₁ ≤ 35 ° and 10 ° ≤ θ ₂ ≤ 25 °. 3. The relationship between the width w from the equatorial plane to a predetermined plane parallel to the equatorial plane forming an angle at which the cord is bent at an inclination angle θ ₂ and the width W from the equatorial plane to the end of the belt layer is as follows. The heavy duty pneumatic tire according to claim 1, which satisfies the condition. 0.2W ≦ w ≦ 0.6W