JPH09123714A - Tubeless tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tubeless tire wherein rim assembling work is improved while the air sealing and durability of a bead part is maintained to the same level as that of a conventional tire when the force of a horizontal direction is applied to the tire and toe cutting is prevented. SOLUTION: The bead base of the bead part 1 of a tire meridian section is composed of a bead heel side portion 21 having a tapered angle β sufficient for adhesion to a rim and a bead toe side portion 22 having a tapered angle αof 4 to 6 deg. up to a point in a position away from a bead toe Q by a distance (m) equivalent to that from the bead heel side end 3 of a bead core width L vertically projected from a bead heel tire shaft to 55 to 65% of the bead core width L. The inner diameter (d) of the bead toe is set to 96.9 to 97.3% of a rim nominal diameter D.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tubeless tire, and more specifically, to a bead portion having an air-sealing property and durability comparable to those of a conventional tire when a large lateral force is applied to the tire such as cornering during high speed running. The present invention relates to a tubeless tire which is improved in workability of assembling a rim while maintaining the rim, and which prevents a toe chipping.

[0002]

2. Description of the Related Art FIGS. 2 (a) to 2 (d) show a conventional bead shape, but as shown in FIGS. 2 (a) and 2 (d), a two-stage structure with improved air inflatability is shown. The taper type has a small bead toe inner diameter and a large rubber volume of the toe portion, which deteriorates rim assembly workability and easily causes toe chipping during assembly work. Further, as shown in FIGS. 2 (b) and 2 (c), even with a single taper for improving the workability of assembling the rim, no improvement in toe chipping is observed.

[0003]

DISCLOSURE OF THE INVENTION The inventor of the present invention has made the following detailed studies on the deformed state of the bead portion of a conventional tubeless tire, and has found the following. That is,
When observing the bead portion of the tubeless tire after traveling a considerable distance, as shown in FIG. 3, the bead toe Q is lifted up and there is no trace of contact with the rim 10. The area actually in contact with the rim 10 is from the bead heel 4 to a region m of 50 to 60% of the bead core width L projected perpendicularly to the tire axis.

FIG. 3 shows a deformed state of the bead portion of the heavy load tubeless tire. Therefore, it was found that the bead toe is effective only when the new tire mounted on the rim is inflated, and has little air sealability and durability after traveling a certain distance.

However, in the case where a large lateral force acts on the tire such as cornering during high speed running, considering the air sealability and durability, a certain amount of toe is used to suppress the lateral movement of the bead portion. Part rubber volume is required. The present invention has been made on the basis of such findings, and its object is to:
While maintaining the air sealability and durability of the bead part at the same level as conventional tires when a large lateral force acts on the tire such as cornering at high speed, improve the rim assembly workability and prevent toe chipping To provide a tubeless tire that has

[0006]

That is, in the tubeless tire of the present invention, a bead heel side portion having a bead base shape of a bead portion in a meridional section of the tire and a bead heel side having a taper angle β sufficient for closely adhering to a rim and a bead toe Q. From the bead heel side end of the bead core width L projected perpendicularly to the tire axis to a point P located at a position m apart by a distance m corresponding to 55 to 65% of the bead core width L, a taper angle α of 4 to 6 °. It has a bead toe side portion, and the bead toe inner diameter d is 9 of the rim nominal diameter D.
It is comprised between 6.9 and 97.3%.

As described above, the bead base shape of the bead portion in the meridional section of the tire is projected from the bead heel side portion having the taper angle β sufficient to be in close contact with the rim and the bead toe Q so as to project perpendicularly to the tire axis. From the bead heel side end of the width L to the bead core width L of 55 to 65
% To a point P located at a position separated by a distance m corresponding to%, the bead toe side portion having a taper angle α of 4 to 6 °, and the bead toe inner diameter d of the rim nominal diameter D of 96.9 to. By setting it to 97.3%, the inner diameter of the bead toe becomes a little larger than that of the conventional tire, and there is a certain amount of toe rubber bolus, so a large lateral force is exerted on the tire such as cornering at high speed. While maintaining the air-sealing property and durability of the bead portion when they act, the workability of assembling the rim can be improved and the toe chipping can be prevented.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A tubeless tire according to the present invention will be described below with reference to the drawings. In FIG. 1, 1
Is a bead portion of a heavy load tubeless tire, and the bead portion 1 is adapted to be incorporated into a rim (not shown) having a 15 ° taper.

The bead base 2 of the bead portion 1 includes a bead heel side portion 21 having a taper angle β sufficient to fit the rim, and a bead heel side having a bead core width L projected from the bead toe Q perpendicularly to the tire axis. Distance m from the end 3 corresponding to 55 to 65% of the bead core width L
Up to a point P, which is separated by a distance, is composed of a bead toe side portion 22 having a taper angle α of 4 to 6 °.

Further, the inner diameter d of the bead toe Q is 96.9 to 97.3% of the nominal rim diameter D. In FIG. 1, reference numeral 4 indicates a bead heel, and 5 indicates a bead core.
With the above configuration, the inner diameter d of the bead toe Q becomes slightly larger than that of the conventional tire and there is a certain amount of toe rubber volume, so a large lateral force acts on the tire such as cornering. In this case, while maintaining the air sealability and durability of the bead portion in the same manner as the conventional tire, it is possible to improve rim assembly workability and prevent toe chipping.

In the above description, the shape of the bead portion of the heavy load tubeless tire incorporated in the rim with a 15 ° taper has been described. It can also be applied to the bead portion of a flat tire.

[0012]

【Example】

(Example 1) Tires of the present invention (tubeless tires) 1 to 3 and comparative tires (tubeless tires) 1 to 14 having the bead portion shape shown in FIG. 1 were produced, and the conventional bead portion shape of FIG. Tire (tubeless tire)
The results of comparison with Table 1 and Table 2 are shown.

From Tables 1 and 2, the tires 1 to 3 of the present invention are
It has been found that while maintaining the air sealability, rim displacement, and durability comparable to those of conventional tires, the workability of rim assembly is improved and toe chipping can be prevented. On the other hand, in Comparative tires 1 to 7, no improvement effect was observed. Further, it was found that the comparative tires 8 to 14 were inferior to the conventional tire in air sealability, rim dislocation property, and durability.

In Tables 1 and 2, the rim assembly workability is represented by a feeling index with the rim assembly workability of the conventional tire being 100. Further, the toe chipping is indicated by an index with the toe chipping occurrence rate of the conventional tire in the rim detachment work after the running test being 100. Further, the decrease in air pressure after the running test was expressed as an index with the conventional tire being 100.

Further, the rim dislocation property is represented by an index with the conventional tire being 100 in the amount of occurrence in the rapid acceleration / deceleration test. Lastly, the durability is the same as that of conventional tires with the incidence of bead failure.
It was indicated by an index of 00.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

As described above, according to the present invention, the bead base shape of the bead portion in the meridian section of the tire has a bead heel side portion having a taper angle β sufficient to make close contact with the rim, a bead toe Q, and a tire shaft. From the edge of the bead heel side of the bead core width L projected perpendicularly to the bead core width L
To a point P located at a position separated by a distance m corresponding to 55 to 65% of the bead toe side having a taper angle α of 4 to 6 °, and the bead toe inner diameter d is equal to the rim nominal diameter D. Since 96.9-97.3%, the rim assembly work is performed while maintaining the air sealability and durability of the bead portion at the same level as the conventional tire when a large lateral force acts on the tire such as cornering at high speed. It is possible to improve toughness and prevent toe chipping.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a bead portion in a tubeless tire according to the present invention.

FIG. 2 (a) is a cross-sectional view of a conventional two-step tapered bead portion. (b) A sectional view of a conventional single-tapered bead portion. (c) A sectional view of a conventional single-tapered bead portion. (d) It is sectional drawing of the conventional bead part with 2 steps taper.

FIG. 3 is an explanatory diagram showing a contact state with a rim of a bead portion of a heavy load tubeless tire.

[Explanation of symbols]

1 bead part 2 bead base part 3 bead heel side end part 4 bead heel 5 bead core 10 rim 21 bead heel side part 22 bead toe side part d bead toe inner diameter D rim nominal diameter L bead core width P point Q bead toe

Claims (1)

[Claims] 1. A bead base shape of a bead portion in a meridional section of a tire, a bead heel side portion having a taper angle β sufficient to adhere to a rim, and a bead core width L projected from a bead toe Q perpendicularly to a tire axis. 4 to 4 from a bead heel side end to a point P located at a distance m corresponding to 55 to 65% of the bead core width L.
The bead toe inner diameter d has a rim nominal diameter D of 96.
A tubeless tire with 9 to 97.3%.