JPH0288309A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To decrease rolling resistance without sacrifice of wear resistance and fatigue resistance in a tread portion by keeping the cross angle of the belt cord of the outside belt ply in a belt layer to the belt cord of the belt ply adjoining to the inside at 30-70 degree. CONSTITUTION:In a belt layer 7 consisting of multiple belt plies arranged along the outer circumference of a carcass 6 in its radial direction belt cords arranged slantwise with regard to the equator of a tire 1 are provided for respective belt plies 12-14, 10. Moreover, the cross angle of the belt cord of the external belt ply 10 positioned on the remotest side in the radial direction, to a middle belt cord 14 adjoining to the inside of the above belt cord is kept at 30-70 degree. This constitution improves the rigidity of a tread 5 and forms a triangle truss structure by the above external and middle belt plies, thus improving the restraint between the belt plies.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention reduces the rolling resistance of the tire without reducing the abrasion resistance and fatigue resistance of the tread, and improves the power consumption of the vehicle by i [L]. Regarding pneumatic radial tires.

[Conventional technology]

In recent years, one of the fuels for power vehicles! FF reduction has become an issue, and there is an increasing demand for tires that can run with low fuel consumption.

Conventionally, in this fuel-efficient tire, rolling resistance has been reduced by using rubber with a small tangential loss, that is, a ratio of the loss modulus of elasticity to the dynamic modulus of elasticity, in the tread portion.

[Problem to be solved by the invention]

However, although rolling resistance is reduced by using a base rubber with low tangent loss in the tread as described above, as a result, the reinforcing properties of the rubber are reduced, and the wear resistance and fatigue resistance of the rubber in the tread are reduced. decreases,
Durability will be reduced.

In order to solve the above-mentioned problem, the inventor conducted extensive research and found that rolling resistance could be reduced by arranging the cords of the belt layer arranged on the outside of the carcass in a specific direction in the tread section. I found it.

In pneumatic tires used for vehicles such as trucks and buses, the bell) arranged on the outside of the carcass in the tread portion is formed by a plurality of belt plies b, c, d, e as shown in Fig. 3. The belt N
The rigidity of a is increased. In addition, in a radial tire for heavy loads, each belt ply b, c, d, e is formed using a high-tensile cord, but usually the outermost belt ply e is formed to improve trauma resistance. is formed so that the inclination of its cord is close to the inclination of the cord of the adjacent belt ply d, and therefore the belt ply e and the belt 754
It has been found that the restraining force between tires 6 and 6 becomes small, and as a result, unnecessary movement occurs in the rubber layer at the ground contact part of the tire, resulting in an increase in rolling resistance.

The present invention is based on regulating the intersection angle between the belt cord of the outer belt ply and the belt cord of the inner belt ply adjacent to the inner side of the outer belt ply.
The purpose of the present invention is to provide a pneumatic radial tire that can reduce rolling resistance without impairing the wear resistance and fatigue resistance of the trend part and can save power and fuel consumption.

[Means to solve the problem]

In order to solve the above problems, the pneumatic radial tire of the present invention includes a carcass that passes from the tread part through the sidewall part and folds around the bead core of the bead part, and a radial outer circumference of the carcass that is attached to the tread part and the outer circumference of the carcass. and a belt layer consisting of a plurality of belt plies, each belt ply having a belt cord inclined with respect to the equator of the tire, and the outermost belt ply located at the outermost side in the radial direction. The belt cord and the belt cord of the inner belt ply adjacent to the inside of the outer belt ply intersect at an angle of 30 degrees to 70 degrees.

[Effect]

In this way, since the pneumatic radial tire includes a belt layer made up of a plurality of belt plies in the tread portion, the rigidity of the tread portion can be increased.

Also, since the belt cord of the outer belt ply located at the outermost side and the belt cord of the adjacent inner belt ply intersect at an angle of 30 degrees to 70 degrees, the outer belt ply and the inner belt ply are This forms a triangular truss structure and increases the binding force between the belt plies. By doing so, it is possible to suppress unnecessary movement at the ground contact part and reduce rolling resistance without reducing the wear resistance and fatigue resistance of the tread part.

〔Example) An embodiment of the present invention will be described below based on the drawings.

In the figure, the pneumatic radial tire 1 of the present invention has bead portions 3.3 on both sides through which the bead core 2 passes, and the bead portions 3.
A sidewall section 4 extends outward in the radial direction of the tire, and a tread section 5 joins the upper end of the sidewall section 4, and a tread section 5 extends from the tread section 5 through the sidewall section 4 and folds around the bead core 2 of the bead section 3. The tire includes a carcass 6 to be returned, and a belt N7 disposed on the tread portion 5 on the outside of the carcass 6 in the tire radial direction.

The carcass 6 is a so-called radial arrangement body in which carcass cords are arranged at an angle of 70 degrees to 90 degrees with respect to the equator C of the tire, and the carcass cords include steel cords as well as fibers such as nylon, polyester, and rayon. code is adopted.

The belt layer 7 is arranged in this order from the carcass 6 side toward the outside in the radial direction of the tire: the inner belt ply 12, the inner belt ply 9, and the outer belt ply 10 at the outermost position. Further, in this embodiment, the inner belt ply 9 has a first inner belt ply 13 disposed on the inner side in the radial direction of the tire;
Therefore, in this embodiment, the belt layer 7 is formed by the inner belt ply 12, the first inner belt ply 13, and the second inner belt ply 14 from the carcass 6 side. It is formed by four belt plies including the inner belt ply 14 and the outer belt ply 10 disposed on the outermost side.

In this embodiment, the width of the first belt ply 13 is made the largest compared to the widths of the other belt plies.

Furthermore, the belt 717 has a respective belt ply 12.13.
．． 14.10 is provided with a belt cord arranged in an inclined manner,
As shown in FIG. 2, in the inner belt ply 12,
The belt cords are arranged at an angle of 15 to 70 degrees upward to the right with respect to the equator C of the tire. Matauchi belt ply 1
In the first inner belt ply 13 adjacent to the outside of the second belt ply,
The belt cords are arranged upward to the right, which is the same direction as the inner belt ply 12, and at a cord angle inclined at an angle of 12 degrees to 30 degrees with respect to the equator C of the tire, while the second inner belt ply 14 In this case, the belt cord is arranged upward to the left and at an angle of 12 degrees to 30 degrees with respect to the equator C of the tire.

The belt cords of the outer belt ply 10 are arranged in a direction that intersects the belt cord of the second inner belt ply adjacent to the inner side of the outer belt ply 10 at an angle of 30 degrees to 70 degrees.

Furthermore, in this embodiment, each belt ply 12.13.14
．． The belt cord 10 is made of a plurality of cords made of high modulus steel and is formed by cutting out a rubberized ply.

In this embodiment, the tread portion 5 is located inside the belt layer 7 in the radial direction, and the breaker cushion layer 21 is disposed on the outside thereof, and the tread N22 is disposed thereon. It is buried between the kutsushiran layers 21. Further, near both ends of the inner belt ply 9 and the outer belt ply 10, low heat generating shoulder gaskets 23 having a substantially triangular cross section are arranged. Shoulder rose bald 23 has inner belt ply 9 and outer belt ply 1
Helps prevent peeling of the edges of the 0.

[Specific Example 1] A trial tire with a tire size of 10.0OR2014PR having the configuration shown in FIG. 1 and with the belt cords of each belt ply arranged in the direction shown in Table 1 was manufactured, and compared with a conventional tire.

Regarding Example 1 and Comparative Example 1 shown in Table 1, the rubber layers forming the cap tread and sidewall were both extracted from the same lot. The test was conducted using a drum running tester under the following conditions.

Device rim 7.0OTx20 Internal pressure 7.25 K S C Load: 2.425kgf Speed 80h/min The test results are shown in Table 1.

[Specific Example 2] A cap tread and a sidewall were prototyped using rubber having a composition different from that of Specific Example 1, and the running resistance of the Example and Comparative Example was compared. The test was conducted under the same conditions as in Example 1 except for the rubber composition. The test results are shown in Table 2.

As a result of the test, it was found that the running resistance of both Examples 1 and 2 was lower than that of the Comparative Example.

(Effects of the Invention) As described above, the pneumatic radial tire of the present invention has a low running resistance as low as the number 41!fi Show that.

Indicates that it is small.

Because the belt cord of the outer belt ply and the belt cord of the inner belt ply adjacent to it intersect at an angle of 30 to 70 degrees, there is no need to use materials with low tangent loss in the tread. By regulating the inclination angle of the belt cord within a certain range, the rolling resistance of the tire can be reduced without reducing the wear resistance and fatigue resistance of the tread, reducing running resistance and reducing power and heat costs. It can save money.

[Brief explanation of drawings]

Fig. 1 is a right half sectional view showing one embodiment of the present invention, Fig. 2 is a plan view showing the developed structure of the belt cord, and Fig. 3
The figure is a plan view showing the structure of a conventional tire belt cord. 2... Bead core, 3-... Bead part, 4...
Sidewall section, 5...Tread section, 6.
-Carcass, 7--Belt layer, 9--Inner belt ply, 10--Outer belt ply. Patent applicant Sumitomo Rubber Industries Co., Ltd. Agent
Patent Attorney Tadashi Naemura 42B

Claims (1)

[Claims] 1. A carcass that passes from a tread portion through a sidewall portion and folds around a bead core of a bead portion, and a belt layer that is disposed on the tread portion and on the outer periphery of the carcass in the radial direction and is composed of a plurality of belt plies, Each of the belt plies has a belt cord inclined with respect to the equator of the tire, and the belt cord of the outer belt ply located at the outermost position in the radial direction and the belt ply of the inner belt ply adjacent to the inner side of the outer belt ply. A pneumatic radial tire made by intersecting the belt cord at an angle of 30 to 70 degrees.