JP2001277823A - Pneumatic tire with tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bead shape improving efficiency in tire rim detaching work by preventing the bead toe section of a pneumatic tire with tube from deforming caused while a vehicle runs. SOLUTION: A bead section can be prevented from deforming by setting the relation among bead base width BW, the total width DW of the bead section and the effective width AW of the bead section to DW>BW>AW. By setting the relation to 0.97>=BW/DW and BW/AW>=1.01, if possible, even for a pneumatic tire with tube for heavy loads used under sever operation conditions, the bead section can be prevented effectively from deforming.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bead shape of a pneumatic tire with a tube, and more particularly, to preventing deformation of a tire bead toe portion due to running of a vehicle.
An object of the present invention is to provide a bead shape for improving the rim attaching / detaching workability when changing tires.

[0002]

2. Description of the Related Art In a conventional pneumatic tire with a tube, particularly a pneumatic tire with a heavy load tube, as shown in FIG. 3, the tip P1 of a bead toe portion 9 on the inner surface side of the tire is located on the inner surface side of the tire from the tire bead portion full width DW. Because
The angle θ between the bead base and the inner surface of the tire (the top angle of the bead toe) is an acute angle. In addition, the bead toe portion 9 is pressed against the rim flange 10a under the influence of the deformation force due to the tire internal pressure and the repetitive deformation force LF due to the load rolling, which are received through the tube flap 11.
As a result, as shown by the deformation mark 9a in FIG. 4, the tire was deformed like a bird's beak on the inner surface side of the tire, making it difficult to attach and detach the tire, especially to remove the bead portion from the rim flange.

[0003] That is, it is necessary to remove the tire from the rim when the tire is completely worn or the like. After releasing the filling air, the ring of the rim is removed, and then the rim flange side of the tire is replaced with the bead breaker 13 or the tire shown in FIG. The tire bead portion is dropped from the rim 10 by crushing the inner surface of the tire with a lever or the like. At this time, when the tire bead toe portion 9 is not deformed, the tire bead portion moves so as to move in parallel with the rim base when the tire side portion is crushed inward, and can be easily removed from the rim 10. But,
As shown in FIG. 4, the tire having the deformation mark 9a in the bead portion has a rotational force MF of the tire bead portion with the deformation mark 9a as a fulcrum.
As a result, the tire bead portion moves so as to rotate in the direction of arrow MF in FIG. 4, and the tire bead portion does not fall off the rim. When the crushed force is released, the tire returns to the original state, and the tire is detached. The work was hindered.

Therefore, various attempts have been made to simply reduce the bead base width BW. For example, it has been attempted to extremely narrow the width of a bead ring of a mold. However, in a bead core obtained by simply winding one piano wire used around a bead of a conventional pneumatic tire with a tube (hereinafter referred to as a single wound bead core), the rigidity of the uncured bead core portion when not vulcanized Is low, and when pressed uniformly from the inside of the tire with a rubber vulcanization bladder at the time of vulcanization, the bead part itself will be deformed to the narrow bead ring width,
On the contrary, it was difficult to attach and detach the rim, which had an adverse effect.

[0005]

On the other hand, there is a strong desire from the market to improve the workability when attaching and detaching tires. In particular, small and medium-sized tire dealers rely on manual labor to supply pneumatic tire mounting rims with tubes. Such a request is urgent because of the desorption work. Therefore, an object of the present invention is to propose a bead portion shape of a pneumatic tire with a tube, which prevents deformation of a bead toe portion due to running of a vehicle, thereby improving workability at the time of attaching and detaching the tire.

[0006]

According to the present invention, a tire including a tire rotation axis of a tube-mounted pneumatic tire having a pair of sidewalls and a pair of beads extending inward in the tire radial direction from both ends of a cap tread. In the bead section, bead base width BW and bead section full width DW
And the effective width AW of the bead portion is DW>BW> A
By setting W, the deformation mark 9a of the bead toe portion 9 of the pneumatic tire with a tube can be effectively prevented.

According to another aspect of the present invention, the relationship between the bead base width BW, the entire bead portion width DW, and the effective bead portion width AW is 0.97 ≧ BW / DW and BW / AW ≧ 1.01. Accordingly, even in the case of a pneumatic tire with a tube for heavy load under more severe use conditions, it is possible to effectively prevent deformation of the bead portion shape and also prevent separation of the edge of the carcass turn-up portion.

According to another aspect of the present invention, the cross section of the bead core 5 constituting the bead portion is formed by molding, for example, a hexagon or a cable bead, so that a stronger cross section is obtained as compared with the conventional single wound bead wire. Therefore, the bead portion itself can be effectively prevented from being deformed even in the case of a pneumatic tire with a heavy load tube, which has particularly severe use conditions. When the bottom of the bead core is a single wire, such as a cable bead, the point at which the point is lowered to the bead base parallel to the tire equatorial plane is P2.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of a detailed study of the mode of deformation of a tire bead portion during running of a vehicle, the present inventor has found that, as shown in FIG. Attention was paid to repeating the deformation in which the bead toe portion 9 is pressed against the rim flange 10a under the influence of the repetitive deformation force LF due to the movement. In this repetitive deformation mode, the contraction force of the flap 11 repeats the movement of pressing the tire bead toe portion 9 toward the rim side, and the tire bead toe portion 9
I knew that a deformation mark 9a would be formed.

The inventors of the present invention have made various investigations, and as a result, FIG.
As in the present invention described above, the relationship between the bead base width BW, the total width DW of the bead portion, and the effective width AW of the bead portion is DW> B.
It has been found that when W> AW, the deformation mark 9a can be significantly reduced. That is, when the tire is rolling, the tire bead toe portion 9 of the tire contact portion is
With the rim flange 10a serving as a fulcrum, the rim is pressed against the rim base via the flap 11 and repeatedly rises up to a portion other than the tire contact portion, so that the flap 11 acts to press the bead toe 9 against the rim 10. However, in the pneumatic tire with a tube of the present invention, the DW is larger than the BW, as shown in FIG. 2, so that the bead toe angle θ becomes obtuse, so that the flap 11 and the bead toe portion 9 easily slip and are pressed against the rim. Such movement is alleviated, and it is possible to significantly reduce deformation marks such as bird's beak.

Here, the bead base width BW is defined as JATM.
In the cross section of the tire bead portion including the standard rim specified in the A99 version and the tire rotation axis filled with the maximum air pressure, the tire and the rim flange 10a are started from the tip P1 of the bead toe portion 9.
Means the width perpendicular to the tire equatorial plane up to the contact portion, and the total bead portion width DW is the height of the center of the bead core 5 in the direction perpendicular to the tire equatorial plane from the tire inner surface to the contact portion between the tire and the rim flange 10a. It means the entire width of the bead portion, and the effective width AW of the bead portion is the point P2 where the position of the bead wire closest to the toe side at the bottom (the rim side of the tire) of the bead core 5 is lowered to the bead base portion in parallel with the tire equatorial plane. It means the width perpendicular to the tire equatorial plane up to the contact portion between the tire and the rim flange 10a.

Further, the BW is closer to the AW than the deformation mark 9a.
Can be reduced, but BW is AW
If it is less than the predetermined value, the bead core 5 cannot sufficiently secure the tightening force of the rim 10, and the movement of the tire bead portion becomes large. Under extreme conditions of use, the car caster nap edge may be separated. Yes.

Further, under severe operating conditions such as a heavy-duty pneumatic tire, the relationship between the bead base width BW, the total width DW of the bead portion and the effective width AW of the bead portion is 0.9.
By satisfying 7 ≧ BW / DW and BW / AW ≧ 1.01, it is possible to more effectively prevent the deformation of the bead portion shape and significantly reduce the deformation mark 9a. Separation can also be prevented.

Further, since the bead core constituting the bead portion is formed of a molded hexagonal cross section or a cable bead, the rigidity of the bead portion is increased. For example, the bead is vulcanized by a mold having a bead ring narrower than the entire width DW of the bead portion. However, unnecessary bead core deformation can be reduced, and good vulcanization can be performed.

[0015]

EXAMPLE An indoor drum durability test was conducted between an example of the present invention and a conventional tire in an indoor drum durability test. After running 20,000 km, the rim was easily attached / detached and the bead toe deformation was compared. Tire size: 1000R20 14PR Air pressure: 725kPa Rim used: 20 × 7.50V Load: 39.72KN (150% of single maximum load) Speed: 45km / hr Drum diameter: 1707mm Tire measurement value after running indoor drum durability test Conventional tire The bead breaker was removed with the help of an L-shaped iron member and a hammer because it was deformed like a bird's beak and it was difficult to remove the rim. The tire of the present invention; easily detached with a bead breaker. Therefore, it was confirmed that the rim attaching / detaching workability of the tire of the example of the present invention and the deformation of the bead toe portion were small and good.

[0016]

The bead shape of the pneumatic tire with a tube according to the present invention makes it possible to prevent deformation of the bead toe portion due to running of the vehicle, and as a result, it is possible to remarkably improve the workability at the time of attaching and detaching the tire. .

[Brief description of the drawings]

FIG. 1 is a half sectional view of an embodiment of the present invention.

FIG. 2 is a partially enlarged view of a cross section of a bead portion according to an embodiment of the present invention.

FIG. 3 is a partially enlarged view of a cross section of a rim mounting bead portion of a conventional tire.

FIG. 4 is an explanatory view of bead toe deformation of a conventional tire.

FIG. 5 is a simplified explanatory diagram of a bead breaker.

[Explanation of symbols]

 Reference Signs List 1 tire tread 2 belt 3 side tread 4 carcass 5 bead core 6 bead filler 7 finishing 8 rim cushion 9 bead toe 9a deformation mark 10 rim 10a rim flange 11 flap 12 tube 13 bead breaker AW bead effective width BW bead base width DW bead Width of MF tire bead

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B60C 15/06 B60C 15/06 G

Claims (5)

[Claims] 1. A bead base width BW in a tire bead section cross section including a tire rotation axis of a pneumatic tire with a tube having a pair of sidewalls and a pair of beads extending inward in a tire radial direction from both ends of a cap tread.
And a relation between a bead portion full width DW and a bead portion effective width AW is DW>BW> AW. 2. The relation between the bead base width BW, the entire bead portion width DW, and the effective bead portion width AW is 0.97 ≧ BW / DW BW / AW ≧ 1.01. Pneumatic tire with tube for heavy loads. 3. The pneumatic tire with a tube according to claim 1, wherein the shape of a bead core constituting a bead portion of the pneumatic tire with a tube has a molded cross-sectional shape. 4. The pneumatic tire with a tube according to claim 1, wherein a bead core constituting a bead portion of the pneumatic tire with a tube has a molded hexagonal cross-sectional shape. . 5. The pneumatic tire with a tube according to claim 1, wherein a bead core constituting a bead portion of the pneumatic tire with a tube comprises a cable bead.