JPH068352A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To provide a pneumatic tire enhanced in the insufficient breaking strength and uniformity of a bead part without lowering productivity. CONSTITUTION:A pair of side wall parts are provided along with the tread part stretching over said side wall parts and the bead parts provided to the inner edges of the side wall parts and these parts are reinforced by at least one toroidal carcass covering the bead cores embedded in the bead parts and outwardly folded back around the bead cores. Each of the bead cores is composed of a composite consisting of winding bundle units 6, 7, 8 formed so as to be divided into a plurality of sections. In the respective winding bundle rings 6, 7, 8, a rubber lined strip 2 composed of parallel filaments to position the winding start end 9 and winding completion end 10 on the same radius line of the winding bundle unit rings 6, 7, 8 or in the vicinity thereof and these positions are arranged on a ring circumference at a substantially equal interval between the winding bundle unit rings 6, 7, 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, in particular, a pneumatic radial tire, which has improved bead breaking strength and uniformity by improving a bead core.

[0002]

2. Description of the Related Art Generally, a pneumatic tire has a bead core regardless of the type of vehicle or the type of tire, and the types are roughly classified into three types. That is, it is a bundled bead core, a spiral bead core, or a round bead core (or a bead core). The bundled bead core is formed by arranging a plurality of filaments in parallel, coating the rubber on the filaments, and spirally winding and winding the rubber-impregnated strips. The spiral bead core is a single rubber-coated filament that is wound in a spiral shape up to a predetermined number and then laminated a plurality of times by the same method. A round bead core is a cord that is twisted and braided (cable bead).

[0003]

Each of these bead cores has advantages and disadvantages. The bundled bead core generally has high productivity and high bead rigidity, but on the other hand, it has a drawback in that the strength utilization rate is low and the rim assembly property and uniformity are deteriorated. The round bead core has a high strength utilization rate, good rim assembly and uniformity, but its productivity is significantly lower than that of the bundled bead core. The spiral bead core exhibits an intermediate property between the above two bead cores.

Among the above-mentioned bead cores, a bundled bead core is improved, and the high productivity, which is an advantage thereof, is maintained as much as possible, and further, a pneumatic tire is provided which has the drawbacks of high utilization factor and uniformity. That is the object of the present invention.

[0005]

SUMMARY OF THE INVENTION The present invention comprises a pair of sidewall portions with a tread portion extending between them and a bead portion at the inner edge of the sidewall portion, and a bead core in which each of these portions is embedded in the bead portion is wrapped around the bead portion. In a pneumatic tire reinforced by at least one toroidal carcass that is folded back outward, the bead core is a composite of a plurality of winding unit rings formed in sections, and each winding unit ring is rubberized with parallel filaments. The strip is wound so that the winding start end and the winding end end are located on the same radius line of the winding unit ring or in the vicinity thereof, and this position is substantially between the winding unit rings on the ring circumference. A pneumatic tire characterized by being arranged at equal intervals.

A pair of sidewall portions are provided together with a tread portion extending between them and a bead portion on the inner edge of the sidewall portion, and each of these portions encloses a bead core embedded in the bead portion and is folded outwardly around it to form a toroidal shape. The present invention relates to an improvement of a bead core among pneumatic tires reinforced with at least one carcass.

FIG. 1 shows the outer appearance of the bundled bead core 1. The bundled bead core 1 is widely used because of its high productivity. FIG. 2 shows a cross section of the conventional bundled bead core 1 taken along line AA. Conventional bundled bead core 1
Is a rubberized strip 2 in which a plurality of filaments 3 are juxtaposed and covered with a rubber 4 are spirally wound a plurality of times to form a ring. This bundle of bead cores 1
Although it is excellent in productivity, since the winding start end 9 and the winding end end 10 of the winding bundle are always present, there is a problem that the strength utilization factor decreases, stress concentration occurs, and uniformity deteriorates. .

In order to solve these problems, therefore, in the present invention, the winding start end 9 and the winding end end 10 are evenly arranged on the circumference of the bead core. FIG. 3A shows a sectional view of the bundled bead core 1 of the present invention taken along the line AA. The bead core 1 includes three winding unit rings 6, 7, 8 in which two filaments 3 are juxtaposed and a rubberized strip 2 covered with a rubber 4 is spirally wound a plurality of times.
Are juxtaposed so as to be adjacent to each other with a plane orthogonal to the rotation axis of the tire interposed therebetween.

In FIG. 3B, each winding bundle unit ring 6, 7,
8 shows a side view of these winding unit rings 6, 7,
Each of the windings 8 has a winding start end 9 and a winding end end 10. In FIG. 3B, the both ends are arranged so that the overlap region 11 exists in the vicinity of the same radius line, but they may not be overlapped. Further, when these winding unit rings 6, 7, 8 are integrated into the bead core 1, the winding end ends 10 of the winding unit rings are arranged at equal intervals on the ring circumference. Deploy. For example, in the case of three winding bundle rings as shown in the drawing, the positions of the winding end ends 10 are shifted so that the center angles of the rings are 120 ° and the winding ends are arranged side by side.

These winding unit rings may have the same inner diameter, but in order to firmly fix the bead core to the rim, from the outer side to the inner side in the width direction of the tire,
It is preferable to reduce the inner diameter of the winding unit ring.

Since the main purpose of the bead core of the present invention is to alleviate stress concentration and improve uniformity, at least two or more winding unit rings are required. In addition, at least two or more winding unit rings may be a bead core that is fitted with winding unit rings of different diameters that are concentric with the rotation axis of the tire and that are adjacent inside and outside. FIG. 4 shows, as an example, two winding bundle unit rings 1 having different ring diameters.
The bead core which integrated 2 and 13 is shown.

The rubber and the filaments of the rubberized strip used for each winding unit ring constituting the bead core may or may not have the same material or physical properties. Further, the number of filaments, the arrangement interval of the filaments, the different rubber, etc. can be appropriately changed according to the application.

[0013]

In the present invention, the winding start end and the winding end end are inevitably present due to the structure of the bundled bead core. However, by forming this bundled bead core into a composite of a plurality of winding bundle unit rings, By arranging the ends and the end of winding between the winding unit rings and distributing them as much as possible on the ring circumference, the stress concentration on the bead core can be relieved, and the strength reduction of the bead core can be suppressed as much as possible. it can. Uniformity can also be improved by arranging the winding end points evenly on the circumference, which also improves vibration and steering stability during high-speed traveling.

[0014]

[Examples] The tires of the present invention and conventional tires are described below.
The productivity, the bead breaking strength, and the uniformity test were conducted. ◎ Test tire The tire size is 31 × 10.50 R15 LT 6PR, and the carcass has polyester (1500 d / 2) cords arranged 90 ° with respect to the plane including the tire's peripheral line, and rubber coated 2
Ply was used. The belt used two rubber-coated steel cords (cord structure: (2 + 6) × 0.23) intersecting each other at 22 ° with respect to the plane including the center line of the tire.

Example This tire has a bead core shown in FIG. In this bead core, three winding unit rings are juxtaposed and integrated. In addition, each winding unit ring 6,
Nos. 7 and 8 were produced by arranging two wires (0.96 mmφ) as filaments 3 side by side, and winding the rubberized strip 2 covered with the rubber 4 in a spiral shape 7 times. At this time, the width of the overlap region in the vicinity of the same radius line of the winding start end 9 and the winding end end 10 of the strip was 70 mm. Further, the positions of the winding end ends 10 between the winding unit rings 6, 7, and 8 were shifted by 120 ° on the ring circumference and integrated. The winding unit rings had the same inner diameter (385.1 mm).

Comparative Example As shown in FIG. 2, an example other than the conventional bundled bead core in which six wires were juxtaposed and a rubberized strip 2 covered with a rubber 4 was spirally wound 7 times. It is the same conventional tire as.

◎ Test Method The productivity, the bead breaking strength, and the uniformity were tested and evaluated. The bead breaking strength is size 15
A test tire was mounted on a rim of × 7 JJ to perform a hydraulic test and evaluate. Uniformity: drum diameter 63in, rim 8 1/2 JJ, tire internal pressure 3.0 kgf / cm ² , load load 835 kg
f, tire rotation speed was tested and evaluated under JASO conditions of 60 rpm. Table 1 shows the results of these tests. In addition,
The numerical values in the table are expressed as index ratios with the value of the conventional tire as 100, and the larger the numerical value, the better the performance.

[0018]

[Table 1]

As described above, the productivity is comparable to that of the conventional product, and the bead breaking strength and uniformity are superior to those of the tire using the conventional bundled bead core.

[0020]

According to the present invention, by improving the bead core, productivity, which is an advantage of the bundled bead core, is hardly reduced, and the breaking strength and uniformity of the bead portion can be significantly improved. .

[Brief description of drawings]

FIG. 1 is a perspective view of a bundled bead core that is a reinforcing member of a pneumatic tire.

FIG. 2 is a cross-sectional view of a conventional bundled bead core taken along the line AA of FIG.

3 (a) is a cross-sectional view of the bundled bead core of the present invention taken along the line AA in FIG. 1, and FIG. 3 (b) is a plan view of each winding bundle unit ring.

4 is a cross-sectional view of the bundled bead core of the present invention taken along the line AA of FIG.

[Explanation of symbols]

 1 Bundled bead core 2 Rubberized strip 3 Filament 4 Rubber 6,7,8 Winding unit ring 9 Winding end 10 Winding end 11 Overlap area 12,13 Winding unit ring

Claims (5)

[Claims] 1. A toroid comprising a pair of sidewall portions together with a tread portion extending between them and a bead portion at an inner edge of the sidewall portion, each of these portions enclosing a bead core embedded in the bead portion and folded outwardly around the bead core. In a pneumatic tire reinforced by at least one layer of carcass, the bead core is a composite of winding unit rings formed in a plurality of sections, and each winding unit ring is wound with a rubberized strip of parallel filaments at a winding start end. And the end of winding are located on the same radius line of the winding unit ring or in the vicinity thereof, and this position is a dispersive arrangement at substantially equal intervals on the ring circumference between the winding unit rings. Pneumatic tire characterized by. 2. The pneumatic tire according to claim 1, wherein the composite of the winding bundle unit rings is a juxtaposition of adjacent winding bundle unit rings with a plane orthogonal to the rotation axis of the tire being sandwiched therebetween. 3. The pneumatic tire according to claim 1, wherein the composite of the winding unit rings is a juxtaposition of the winding unit rings having different inner diameters. 4. The pneumatic tire according to claim 1, wherein the composite of the winding unit rings is fitted with winding unit rings of different diameters which are concentric with the rotation axis of the tire and are adjacent to the inside and outside. 5. The pneumatic tire according to claim 1, wherein the parallel filaments are made of metal.