JP3825893B2 - Pneumatic tire - Google Patents

Description

表１から明らかなように、本発明は、リムから外れた回数が０であり、耐リム外れ性を大きく改善できることが判る。
【００１１】
【発明の効果】
上述したように本発明は、ビード部外側面にリムプロテクトバーを突設した空気入りタイヤにおいて、リムプロテクトバーよりタイヤ径方向内側のビード部外側面に少なくとも１本の周方向溝を設けたので、耐リム外れ性を向上することができる。
【図面の簡単な説明】
【図１】本発明の空気入りタイヤのビード部の一例を示す断面図である。
【図２】図１の作用説明図である。
【図３】従来タイヤの要部を示す作用説明図である。
【符号の説明】
１ ビード部 １ａ，１ｂ 外側面
２ ビードコア ３ ビードフィラー
４ カーカス層 ５ リムプロテクトバー
６ 周方向溝 Ｒ リム
Ｒ１ リムフランジ Ｒ２ リムベース[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire in which a rim protection bar is provided in a bead portion so as to improve rim detachment resistance.
[0002]
[Prior art]
In general, in rally tires and high-performance tires with a large inner diameter, an annular rim protection bar that protrudes outwardly from the rim flange on the outer surface of the bead is used to protect the rim flange and improve the fitting force. Is provided.
Such a pneumatic tire has a large gap between the outer surface 12 of the bead portion 10 on the inner diameter side of the rim protect bar 11 and the rim flange 13 due to lateral force during cornering as shown in FIG. When traveling in a muddy area with many corners, mud enters the open gap, and the gap closes when traveling straight, so the mud that has lost its escape is pressed against the rim flange 13. During running, the soil that has been sandwiched and hardened gradually becomes thicker as a result of the repetition, so that the bead portion 10 falls from the rim base 14 and comes off the rim.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide a pneumatic tire provided with a rim protect bar, in which the rim detachment resistance can be improved.
[0004]
[Means for Solving the Problems]
The present invention that achieves the above object is a pneumatic tire in which a rim protect bar projects from an outer surface of a bead portion on which a bead core is disposed, and the bead portion on the side facing the rim flange on the inner side in the tire radial direction from the rim protect bar. A circumferential groove is annularly formed on the outer surface.
By forming the circumferential groove on the outer surface of the bead portion on the inner side in the tire radial direction of the rim protect bar in this way, when a lateral force is applied during cornering, the portion provided with the circumferential groove is deformed as a bending point. As a result, it is possible to suppress the opening between the outer surface of the bead portion on the inner circumferential side of the circumferential groove and the rim flange. In addition, even if mud enters due to some opening, mud pushed out when it closes can be released into the circumferential groove, so the sandwiched soil does not harden and grow thick, so the bead part It does not fall easily from the rim base.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows an example of a main part of the pneumatic tire according to the present invention, where 1 is a bead portion, 2 is a bead core, 3 is a bead filler, and R is a rim mounted. An end portion 4 a of the carcass layer 4 is folded back from the tire inner side to the outer side so as to sandwich the bead filler 3 around the bead core 2. An annular rim protect bar 5 that protrudes outward from the rim flange R1 is provided on the outer surface 1a of the bead portion 1 on the outer side in the tire radial direction.
[0006]
Two circumferential grooves 6 are annularly arranged on the bead outer surface 1b facing the rim flange R1 on the inner side in the tire radial direction from the rim protect bar 5 and on the outer side in the tire radial direction from the bead core 2. Yes. The end 4a of the carcass layer 4 extends from the circumferential groove 6 to the outer side in the tire radial direction.
In this way, by arranging the circumferential groove 6 on the bead portion outer surface 1b on the inner side in the tire radial direction from the rim protect bar 5, as shown in FIG. Since the provided portion is easily bent, the groove is deformed as a bending point, and the opening between the bead portion outer surface 1b and the rim flange R1 on the inner diameter side of the circumferential groove 6A on the inner side in the tire radial direction is suppressed. Can do. Moreover, even if mud enters by a slight opening, it can be pushed out and released into the groove 6A when it is closed, so that a phenomenon in which the soil that is sandwiched and hardened gradually becomes thicker is not caused. Accordingly, it is possible to prevent the bead portion 1 from falling from the rim base R2 and coming off the rim R.
[0007]
In the present invention, the groove depth and groove width of the circumferential groove 6 can be in the range of 2 to 5 mm, respectively. If it is smaller than 2 mm, it is difficult to obtain the above improvement effect.
As the number of the circumferential grooves 6, two examples are shown in the above embodiment, but three or one may be provided depending on the tire size, and at least one may be provided. Preferably, it can be 2-3.
[0008]
The present invention can be preferably used for a pneumatic tire that travels in a muddy area particularly in a rally, etc., but if a rim protect bar is provided to improve the rim flange protection and fitting force, Any pneumatic tire may be used.
[0009]
【Example】
A pneumatic tire with a common tire size of 195 / 65R15 and a rim protect bar, and a tire according to the present invention with a circumferential groove as shown in FIG. 1 and a conventional tire without a circumferential groove as shown in FIG. did.
When each of these test tires was subjected to an evaluation test of rim detachment resistance under the measurement conditions shown below, the results shown in Table 1 were obtained.
Rim detachment resistance Each test tire is mounted on a rim with a rim size of 15 x 6 1/2 JJ, mounted on a 2000 cc vehicle with an air pressure of 200 kPa, and the number of rim detachments is measured when the lap runs 10 laps on a 1km 2km dirt course. did.
[0010]
[Table 1]

As is apparent from Table 1, it can be seen that the present invention has a zero number of detachment from the rim and can greatly improve the rim detachment resistance.
[0011]
【The invention's effect】
As described above, in the pneumatic tire in which the rim protect bar protrudes on the outer surface of the bead portion, at least one circumferential groove is provided on the outer surface of the bead portion on the inner side in the tire radial direction from the rim protect bar. Further, the rim detachment resistance can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a bead portion of a pneumatic tire according to the present invention.
FIG. 2 is an operation explanatory diagram of FIG. 1;
FIG. 3 is an operation explanatory view showing a main part of a conventional tire.
[Explanation of symbols]
1 Bead part 1a, 1b Outer side surface 2 Bead core 3 Bead filler 4 Carcass layer 5 Rim protect bar 6 Circumferential groove R Rim R1 Rim flange R2 Rim base

Claims (5)

A pneumatic tire which projects the rim protection bar to the outer surface of the bead portion arranged bead cores, a circumferential groove in an annular bead outer side of the side facing the tire radial direction inner side of the rim flange from the rim protection bar Pneumatic tire provided.   The pneumatic tire according to claim 1, wherein a groove depth and a groove width of the circumferential groove are 2 to 5 mm, respectively.   The pneumatic tire according to claim 1, wherein the circumferential groove is provided on the outer side in the tire radial direction from the bead core. The carcass layer having an end folded around the bead core from the inside to the outside of the tire, and the end of the carcass layer extends from the circumferential groove to the outside in the tire radial direction. The described pneumatic tire. The pneumatic tire according to claim 1, wherein the number of circumferential grooves is two to three.

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