JP2682902B2 - Tubeless radial tires for heavy loads - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heavy-duty tubeless radial tire capable of withstanding a large radial tire even under a super-heavy load condition of overload exceeding 200%.

[0002]

2. Description of the Related Art FIG. 2 shows an example of the structure of a general bead portion of a large radial tire such as a radial tire for trucks or buses. The radial tire is a bead core 1
0, bead apex 11, case (ply) 12,
It is composed of a steel filler 14, a side wall 15, a chafer 16, and the like. In the radial tire having such a structure, when generally used, that is, when the load is 150% or less of the maximum load of JIS standard,
It is said that there will be no problem in terms of durability. However, when the above load is used under a heavy load condition of more than 150%, the bead portion is damaged in this structure. Therefore, as shown in FIGS. 3 and 4, the bead portion is prevented from being damaged. Therefore, a special bead structure was adopted to distinguish them as heavy-duty tires. That is, FIG.
Then, the second reinforcing steel filler 20 is added to alleviate the strain concentrated on the edge portion, and the steel filler 14 and the second reinforcing steel filler 20 partially overlap each other in the vicinity of the bead core 10, thereby improving the bead durability. It is designed to withstand heavy loads. Further, in FIG. 4, in addition to the second reinforcing steel filler 20, the outside of the winding edge portion of the case 12 is further reinforced with an organic fiber 21 such as nylon.

[0003]

However, even with such a special structure, the load is 2% of the maximum load of the standard.
When used under a super-heavy load condition of more than 00%, the bead portion was damaged and durability was problematic.

Therefore, an object of the present invention is to solve the above problems, to improve the bead durability, and to endure even under a super heavy load condition in which the load exceeds 200% of the maximum load of JIS standard. It is to provide a heavy-duty tubeless radial tire that can be used.

[0005]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present inventor conducted an indoor durability machine test, reproduced the usage conditions in the market, and evaluated it with various specifications. This special endurance test condition uses a radial tire of 225 / 90R17.5, and the load is 33 which is the maximum load of JIS standard.
6%, speed 20 km / h, rim 6.75 × 17.
5, the internal pressure was set to 10 kg / cm ² , and the tire was rotated under pressure by contacting the tire with a drum driven to rotate, and the tire was rotated to evaluate durability. The tire is as shown in FIG. 3, the case has a carcass cord angle of 90 degrees and one steel ply, and
The belt is composed of three layers, and the cord direction of the first belt is 67 degrees with respect to the tire circumferential direction, and the cord directions of the second to third belts are steel belts with 17 to 21 degrees with respect to the tire circumferential direction. Here, the above terms will be defined with reference to FIG. First, the “carcass hoisting height N” is defined as follows. The "carcass" is a carcass main body portion extending from the tread portion to the axially inner portion of the bead core through the sidewall portion, and a carcass winding portion that is connected to the main body portion and is wound around the bead core from the axially inner side to the outer side, Is to have. Therefore, “carcass hoisting height N” means “the upper end point of the carcass hoisting portion,
Radial distance N ”from the bead reference line.
Next, the "filler entrainment height O" is defined as follows. "First Steel Reinforcing Filler (14)"
Has an inner portion arranged axially inside the bead core (10) and a steel reinforcing filler winding portion which is connected to the inner portion and is wound around the bead core (10) from the inner side to the outer side in the axial direction. It is a thing. Therefore, the "filler winding height O" means "a radial distance O between the upper end point of the steel reinforcing filler winding portion and the bead reference line". Next, "Side gauge J" is
The term "distance J between the upper end point of the carcass hoisting portion and the point where a straight line passing through the upper end point of the carcass hoisting and perpendicular to the tangent to the side surface portion of the tire intersects the side surface portion". Next, "Bead Apex Gauge I" is defined as "the upper end point of the carcass hoisting portion and a straight line passing through the upper end point of the carcass hoisting and perpendicular to the tangent line of the carcass main body to the axial outer surface of the main body. It means the distance I'between the intersecting points. Next, the "bead core gauge M" passes through the "outermost apex which is the uppermost point in the radial direction of the portion where the bead core is placed on the outer side in the axial direction and contacts the carcass, and is perpendicular to the tangent line of the carcass body. A straight line means a distance M ″ between two points that intersect the axially outer side surface of the carcass body and the side surface. Note that, in FIG. 3, the “bead reference line” means “the innermost surface point located on the innermost side in the radial direction on the radially inner surface of the inner portion of the bead core (10) of the second steel reinforcing filler (20). A straight line extending through and extending parallel to the tire axis ”.

The results of the durability machine test are shown in FIG. 1 and Table 1. From this result, the bead apex gauge (I) and the side gauge (J) at the second steel reinforcing filler winding height (P1) and carcass winding height (N) are extremely excellent in bead durability performance under ultra-high load. It turned out to be important. That is, the second steel reinforcing filler winding height (P1) is 4.3Q ≦ P1 ≦ 5.5Q with respect to the rim flange height (Q) (see FIG. 4),
Further, the bead apex gauge (I) and the side gauge (J) at the carcass winding height (N) are 1.1M ≦ I + J ≦ 1.25 with respect to the bead core portion gauge (M).
It has been proved that the bead durability performance under an ultra-high load is remarkably improved when M, preferably 1.12M ≦ I + J ≦ 1.23M, is satisfied. Where (I + J) /
The reason why M is preferably in the range of 1.1 to 1.25 is 1.1
If it is less than the above range, the amount of deflection of the bead increases when a load is applied, and the turn-up edge portion is greatly distorted. On the other hand, if it exceeds 1.25, the amount of flexure is small, but the physical properties of the rubber are likely to deteriorate due to heat, and breakage is likely to occur. The measurement line of the bead core gauge (M) passes through the apex of the bead core, which is the outermost end on the rim flange side, as shown in FIG. 3, and is perpendicular to the case line (tangent line). The measurement line of the bead apex gauge (I) is also perpendicular to the tangent line of the case. Also, the measurement line of the side gauge is perpendicular to the side surface line.

[0007]

[Table 1]P1 / Q (I + J) / M Endurance index  Comparative Example 1 4.0 0.9 100 Example 4.8 1.22 140 Example 4.4 1.15 140 Example 4.9 1.17 150 Example 4.3 1.1 115 Example 5. 5 1.25 110 Example 4.3 1.25 115Comparative Example 2 4.2 1.25 105  Size: 225 / 90R17.5 Case code: Steel. 90 ° 7 x 4 / 0.175

In Table 1, the larger the value of the durability index, the better the durability performance.

Therefore, according to the result of the above test, in order to achieve the above object, the present invention maintains the above-mentioned steel reinforcing filler winding height (P1) and rim flange height (Q) in a predetermined relationship, The bead apex gauge (I) and the side gauge (J) at the carcass winding height (N) are configured to be within a predetermined range with respect to the bead core portion gauge (M). That is, in a pneumatic tubeless tire for a 15-degree tapered rim, a first steel reinforcing filler (14) wound around the bead core (10) to reinforce the bead portion, and inside the case (12) around the bead and A second steel reinforcing filler (20) for reinforcing a bead portion arranged without winding around the bead core inside the tire along the case (12) and having a carcass hoisting height (N) of steel reinforcing filler. While having a bead structure higher than the winding height (O), the steel reinforcing filler winding height (P1) is 4.3Q ≦ P1 ≦ 5.5Q with respect to the rim flange height (Q), and The bead apex gauge (I) and the side gauge (J) at the carcass hoisting height (N) are the core of the bead core part. Against di (M), it is configured to be in a range satisfying 1.1M ≦ I + J ≦ 1.25M.

In the above structure, the end portion of the first steel reinforcing filler (14) is arranged so as to overlap with the inside of the winding edge portion side end portion of the second steel reinforcing filler (20) by a predetermined range. It can also be configured to.

[0011]

Embodiments of the present invention will be described below in detail with reference to FIGS. 1 and 3.

The tubeless tire according to this embodiment is
As shown in FIG. 3, in a pneumatic tubeless tire for a 15-degree taper rim, a first steel reinforcing filler 14 wound around the bead core 10 to reinforce the bead portion, and inside the case 12 around the bead and the case. 12 and a second steel reinforcing filler 20 for reinforcing the bead portion, and the inner end portion of the first steel reinforcing filler 14 is within a predetermined range inside the winding edge portion side end portion of the second steel reinforcing filler 20. The bead durability can be endured even under heavy load conditions by overlapping only. The carcass hoisting height (N) of the edge portion of the case 12 is higher than the steel reinforcing filler hoisting height (O). Further, as described above, the height at which the steel reinforcing filler is wound (P1)
Is 4.3Q ≦ P1 ≦ for the rim flange height (Q)
The bead apex gauge (I) and the side gauge (J) at 5.5Q and the carcass winding height (N) are 1.1 with respect to the bead core portion gauge (M).
It should be in a range that satisfies M ≦ I + J ≦ 1.25M. The case 12 is a ply of at least one layer of steel or organic fiber having a carcass cord angle of 70 to 90 degrees with respect to the tire circumferential direction, and the belt is made of at least three layers of steel or organic fiber. It is preferable that the cord direction of the first belt is 67 degrees with respect to the tire circumferential direction, and the cord direction of the second to fourth belts is 17 to 21 degrees with respect to the tire circumferential direction.

According to the above embodiment, the second steel reinforcing filler winding height (P1) is 4.3Q ≦ P1 ≦ 5.5Q with respect to the rim flange height (Q), and the carcass winding is The bead apex gauge (I) and the side gauge (J) at the height (N) are 1.1M ≦ I + J ≦ 1.25 with respect to the bead core gauge (M).
Within the range of M, preferably 1.12M ≦ I + J ≦ 1.23M, the bead durability performance under an extremely high load can be remarkably improved. Therefore, the durability performance in the market can be improved, and it becomes unnecessary to add the reinforcement with the organic fiber such as nylon as shown in FIG. 4 in addition to the second steel reinforcing filler 20.

[0014]

According to the structure of the present invention, the second steel reinforcing filler winding height (P1) is 4.3Q ≦ P1 ≦ 5.5Q with respect to the rim flange height (Q), and , The bead apex gauge (I) and the side gauge (J) at the carcass winding height (N) are 1.1M ≦ I + J ≦ 1.25 with respect to the bead core portion gauge (M).
Within the range of M, preferably 1.12M ≦ I + J ≦ 1.23M, the bead durability performance under an extremely high load can be remarkably improved. Therefore, the durability performance in the market can be improved, and it becomes unnecessary to add reinforcement with organic fibers such as nylon in addition to the second steel reinforcing filler.

[Brief description of the drawings]

FIG. 1 is a diagram showing a result of a durability machine test.

FIG. 2 is a sectional view showing a conventional standard bead structure.

FIG. 3 is a sectional view of a reinforced bead structure for explaining a radial tire according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a conventional reinforced bead structure.

[Explanation of symbols]

10 Bead Core, 11 Bead Apex, 12
Case, 14 1st steel reinforcing filler, 15 sidewall, 16 chafer, 20 2nd steel reinforcing filler, 21 Nylon filler.

Continuation of front page (56) Reference JP-A-1-317814 (JP, A) JP-A-2-267012 (JP, A) JP-A-60-61316 (JP, A) JP-A-63-43805 (JP , A) JP 63-87304 (JP, A) JP 61-16106 (JP, A) JP 61-268507 (JP, A) JP 59-63207 (JP, A) JP 61-275010 (JP, A) JP-A-62-113610 (JP, A)

Claims (2)

(57) [Claims] 1. In a pneumatic tubeless tire for a 15-degree taper rim, a first steel reinforcing filler (14) wound around a bead core (10) to reinforce a bead portion, and an inside of a case (12) around the bead. And a second steel reinforcing filler (20) that reinforces the bead portion arranged without winding around the bead core inside the tire along the case (12), and the carcass hoisting height (N) is While having a bead structure higher than the rolled-up height (O) of the steel reinforcing filler, the rolled-in height (P1) of the steel reinforcing filler
Is 4.3Q ≦ P1 ≦ for the rim flange height (Q)
The bead apex gauge (I) and the side gauge (J) at 5.5Q and the carcass winding height (N) are 1.1 with respect to the bead core portion gauge (M).
A tubeless radial tire for heavy loads, characterized in that it is in a range that satisfies M ≦ I + J ≦ 1.25M. 2. The first steel reinforcing filler (14)
2. The tubeless radial tire for heavy load according to claim 1, wherein the end portion of the second steel reinforcing filler (20) is arranged so as to overlap with the inside of the end portion on the winding edge side of the second steel reinforcing filler (20) by a predetermined range.