JP2002331810A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent early damage of a bead part without absorbing shearing force when importance is attached to the prevention of rubbing with the rim. SOLUTION: In the structure of the bead part 4, a rise part 7 of abrasion rubber 8 for preventing rubbing with the rim 1 is set to be higher than a rim flange part 3, the rise part 7 is set to be lower than a shearing region A, and soft rubber 14 for absorbing shearing distortion is held by bonding rubber 11 and the rise part 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire used for heavy loads such as trucks and buses, and more specifically to a pneumatic radial tire which prevents bead damage due to shear strain of a carcass ply edge. It is about.

[0002]

2. Description of the Related Art FIGS. 6 and 7 show pneumatic radial tires used for heavy loads such as trucks and buses. 6 and 7, a seating portion 6 along the rim base portion 2 and a rising portion 7 along the rim flange portion 3.
An abrasion rubber 8 having a substantially L-shaped cross section is provided in the bead portion 4 in which the bead core 5 is embedded, and the end of the radial carcass ply 9 is folded back from inside to outside around the bead core 5 and radially outwardly extended. A folded portion 10 is formed, and an edge of the folded portion 10 is bonded to a bonding rubber 11.
Surrounded by

[0003] A bead filler rubber (also referred to as bead abex) 12 is provided on the bead core 5, and the rubber 12 is a first bead filler rubber 12 having a substantially triangular cross section.
A and the second bead filler rubber 12B joined to the outside of the rubber. Further, the folded portion 10 of the carcass ply 9 has a steel filler 1 having a U-shaped cross section.
The rising portion 7 of the abrasion rubber 8 is sandwiched between the bonding rubber 11 and the side rubber 14. In the example of FIG. 7, a relief rubber 15 is interposed between the bonding rubber 11 and the rising portion 7.

[0004]

The pneumatic radial tire shown in FIGS. 6 and 7 has an abrasion rubber in order to prevent damage due to chafing at the rim base 2 and the rim flange 3 of the rim 1. 8 has a high hardness (Hd: 65 to 85), and the rising portion 7 is extended in a radially outward direction.
In addition, due to the structure of the tire, a ply 9 for supporting the internal pressure and load is provided.
7 is surrounded by a bonding rubber 11 having a hardness of 60 to 80 because a large shear strain acts on the surrounding rubber, and in the example shown in FIG.
5 prevents bead damage due to shearing force generated at the ply edge.

However, since the rising portion 7 of the abrasion rubber 8 is located at a position outside the diameter of the ply edge, it is difficult to sufficiently absorb the shearing force generated at the edge because of high rubber hardness. Bead damage was caused. Further, since the abrasion rubber 8 is a rubber having a high hardness and a small amount of an antioxidant, a weather crack (ozone crack) is induced in the bead portion 4. Therefore, the present invention prevents damage to the bead portion by using a rubber material that can remove the position of the rising portion of the rubber from the shearing region and sufficiently absorb the shearing force while preventing damage due to rubbing with the rim by the abrasion rubber. It is an object of the present invention to provide a pneumatic radial tire.

[0006]

According to the present invention, a seating portion 6 along a rim base portion 2 and a rising portion 7 along a rim flange portion 3 are provided.
An abrasion rubber 8 having a substantially L-shaped cross section is provided in the bead portion 4 in which the bead core 5 is embedded, and the end of the radial carcass ply 9 is folded back from inside to outside around the bead core 5 and radially outwardly extended. A folded portion 10 is formed, and an edge of the folded portion 10 is bonded to a bonding rubber 11.
In order to achieve the above-mentioned object, the following technical measures are taken for the pneumatic radial tire surrounded by.

That is, in the pneumatic radial tire according to the first aspect, the height of the rim flange portion 3 is H1, and the height of the rising portion 7 of the abrasion rubber 8 is H.
2. When the height of the edge of the folded portion 10 is H3, H
1 <H2 <H3, and a soft rubber 14 for absorbing the shear strain generated between the bonding rubber 11 and the rising portion 7 of the abrasion rubber 8 is sandwiched therebetween. It is characterized by the following. With such a configuration, the seating portion 6 and the rising portion 7 which are the contact portions with the rim 1 reliably prevent damage due to rubbing with the rim 1.

On the other hand, the rising portion 7 is deviated from the shearing region A generated at the ply edge as a radial position, and a soft rubber 14 is interposed in this portion to sufficiently absorb the shearing strain. Even under heavy load conditions, damage to the bead portion 4 is reliably prevented. 2. The bonding rubber 11 according to claim 1, wherein the rising portion 7 of the abrasion rubber 8 has a rubber hardness of 65 to 85. 3.
It is recommended that the rubber hardness of the soft rubber 14 is set to 50 to 65, respectively (claim 2).

Further, in claim 1 or 2, the soft rubber 14 is a sidewall rubber 14, and the sidewall rubber 14 extends radially inward between the rising portion 7 of the abrasion rubber 8 and the bead core 5. It is recommended that the stretched rubber 14A be clamped (claim 3). Further, according to claims 1 to 3, a wedge-shaped female portion 14B is formed inside the diameter of the sidewall rubber 14 as the soft rubber 14, and the rising portion 7 of the abrasion rubber 8 is inserted into the female portion 14B. It is recommended to be formed on the male portion 7A of the (claim 4).

Further, a steel filler 13 having a U-shaped cross section is provided on the outer periphery of the radial carcass ply 9 which is turned from the inside to the outside around the bead core 5. It is recommended that the height H4 be larger than the edge height H3 of the folded portion 9 (claim 5). According to this, the bead portion rigidity can be improved by the steel filler 13, the durability is also improved, and the steering stability is also improved. The first bead filler according to claim 1, wherein a first bead filler rubber 12A having a substantially triangular cross section is provided on the bead core 5, and a second bead filler rubber 12B is provided outside the filler rubber 12A. It is recommended that the height H5 of the rubber 12A be larger than the edge height H3 of the folded portion 9 (claim 6).

According to this, the rigidity and the durability of the bead portion can be improved as compared with the conventional example as in the above-mentioned claim 5. Further, it is recommended to combine the above-described claims 5 and 6, whereby the rigidity and durability of the bead portion can be greatly improved (claim 7).

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, first to fifth embodiments (first to fifth embodiments) of the present invention will be described with reference to FIGS. Note that the configuration described above with reference to FIGS. 6 and 7 uses the common reference numerals. In the first embodiment shown in FIG. 1, the height of the rim flange 3 in the rim 1 is H1, the height of the rising portion 7 in the abrasion rubber 8 is H2, and the ply edge of the folded portion 10 in the carcass ply 9 ( H1 <H when height is H3
2 <H3.

The abrasion rubber 8 having the seating portion 6 and the rising portion 7 and having a substantially L-shaped cross section and having a hardness (JIS Shore A hardness; the same applies hereinafter) of 65 to 85 is brought into contact with the rim 1 (rim). By fitting, the bead portion 4 is prevented from being damaged by rubbing with the rim 1, and the rising portion 7 is located below the shearing region A by the carcass ply edge. In addition, the shear area A
Indicates a region having a radius of 2 / 3J of the length I when the thickness from the ply edge to the outer rubber layer is J.

Further, a soft material having a hardness of 50 to 65 for absorbing the shear strain generated between the bonding rubber 11 having a rubber hardness of 60 to 80 and the rising portion 7 of the abrasion rubber 8 is provided. The rubber 14 is sandwiched, and the soft rubber 14 is substantially a side wall rubber. The rubber 14 is stretched so as to be tapered in the radial direction, and the stretched rubber 14 </ b> A is formed between the rising portion 7 and the bead core 5. Are pinched. The rising portion 7 of the abrasion rubber 8 comes off below the shearing region A, and the soft rubber 14
Thus, even if the load is high, the shear force is relaxed and absorbed to secure the rigidity of the bead portion 4 and prevent damage.

FIG. 2 shows a second embodiment. Since the basic structure and operation are common to those of the first embodiment, common parts are denoted by common symbols, and differences will be described. A wedge-shaped female portion 1 tapered outward in a radially inner side (radial inner side) of a soft rubber 14 which is substantially a side wall rubber.
4B are formed, and are formed in a wedge-shaped male portion 7A in which the rising portion 7 is inserted into the female portion 14B and are joined to each other.
According to the second embodiment, the height H2 is slightly higher than that of the first embodiment and approaches the shearing region A, whereby the rigidity of the bead portion 4 is improved and steering stability is secured. On the other hand, since the male portion 7A is sandwiched between the soft female portions 14A, the shearing force is sufficiently relaxed and absorbed.

FIG. 3 shows a third embodiment. Since the basic structure and operation are common to those of the first embodiment, common parts are denoted by common reference numerals, and differences will be described. The inner edge height H4 of the steel filler 13 having a U-shaped cross section disposed on the outer periphery of the folded portion (bent portion) 10 of the radial carcass ply 9 is made higher (larger) than the height H3 of the folded portion 10. (In the first and second embodiments, the cross-sectional height of the steel filler 13 is lower than H3), thereby improving the rigidity of the bead portion 4 and improving the durability and improving the steering stability. It is secured.

FIG. 4 shows a fourth embodiment. Since the basic structure and operation are common to those of the first embodiment, common portions are denoted by common symbols, and differences will be described. The cross section height of the first bead filler rubber 12A having a substantially triangular cross section is substantially the same as the ply edge height H3 in the first to third embodiments. 4th
In the embodiment, the cross-sectional height H5 of the filler rubber 12A is higher (larger) than H3, thereby improving the rigidity of the bead portion 4 and ensuring the steering stability.

In the first to fourth embodiments, the hardness of the bead filler rubber 12 is preferably such that the first rubber 12A is hard and the second rubber 12B is soft. In addition, in the fifth embodiment shown in FIG. 5, the basic configuration and operation are common to those of the first embodiment. In the fifth embodiment, the third and fourth embodiments are combined, and H3 <H4 <H5, and the rigidity of the bead portion 4 is increased.

It should be noted that the above-described second embodiment is modified from third to fifth embodiments.
It is also possible to combine the above embodiments. In the first to fifth embodiments, the soft rubber 14 is the same as that shown in FIG.
May be used as the cushioning rubber 15, or the cushioning rubber 15 may be added to the soft rubber 14.
Next, in order to confirm the durability of the bead portion, a drum test was performed under conditions of high load and high internal pressure, and the bead durability was measured by the time until the bead portion was damaged. Table 1 also shows the conventional example (2) shown in FIG. 7 and the embodiments (1) to (5) shown in FIGS.

[0020]

[Table 1]

In Table 1, the index of the conventional example (1) is set to 100, and it is understood that the durability of each of the examples (1) to (5) is greatly improved. Further, in order to confirm the weather cracking performance of the bead portion, a weather crack test was performed on Conventional Examples (1) and (2) and Examples (1) to (5). Here, the weather crack test refers to a test in which a certain amount of gaseous ozone is continuously blown onto a bead portion to evaluate the degree of crack generation. When the result of this test was evaluated by an index, the result of Example (1) was 100, while that of Conventional Examples (1) and (2) was 100.
-(5) was 160, and it was confirmed that the weather cracking performance of the bead portion was also improved.

The reference for the heights H1 to H5 is the center of the axle or the rim base.

[0023]

As described in detail above, according to the present invention, a pneumatic tire for heavy load which can greatly improve the durability of the bead portion and has excellent steering stability can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part showing a second embodiment of the present invention.

FIG. 3 is a sectional view of a main part showing a third embodiment of the present invention.

FIG. 4 is a sectional view of a main part showing a fourth embodiment of the present invention.

FIG. 5 is a sectional view of a main part showing a fifth embodiment of the present invention.

FIG. 6 is a cross-sectional view of one main part of a conventional example.

FIG. 7 is a cross-sectional view of two main parts of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rim 2 Rim base part 3 Rim flange part 4 Bead part 5 Bead core 6 Seating part 7 Rise part 8 Ablation rubber 9 Carcass ply 10 Folding part 11 Bonding rubber 12 Bead filler rubber 13 Steel filler 14 Soft rubber

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

Claims (7)

[Claims] 1. A seat (6) along a rim base (2).
A radial carcass ply (9) is provided with an abrasion rubber (8) having a substantially L-shaped cross section and a rising portion (7) along a rim flange portion (3) in a bead portion (4) in which a bead core (5) is embedded. Of the bead core (5)
A pneumatic radial tire having a folded portion (10) that is folded from the inside to the outside and extends in the radially outward direction, and the edge of the folded portion (10) is surrounded by bonding rubber (11). The height of the rim flange portion (3) is (H1), the height of the rising portion (7) in the abrasion rubber (8) is (H2), and the edge height of the folded portion (10) is (H3).
In this case, the relationship of (H1) <(H2) <(H3) is established, and is generated between the bonding rubber (11) and the rising portion (7) of the abrasion rubber (8). Soft rubber for absorbing shear strain (1
4) A pneumatic radial tire characterized in that 4) is clamped. 2. The rubber hardness of the rising portion (7) of the abrasion rubber (8) is 65 to 85, the rubber hardness of the bonding rubber (11) is 60 to 80, and the soft rubber (14) The pneumatic radial tire according to claim 1, wherein the rubber hardness is set to 50 to 65, respectively. 3. The soft rubber (14) is a sidewall rubber (14), and the sidewall rubber (14) is located between a rising portion (7) and a bead core (5) in the abrasion rubber (8). The pneumatic radial tire according to claim 1 or 2, wherein the stretched rubber (14A) is stretched in a radial direction and the stretched rubber (14A) is sandwiched. 4. A wedge-shaped female part (14B) is formed inside the diameter of the side wall rubber (14), which is the soft rubber (14), and a rising part (7) of the abrasion rubber (8) is formed by the female part. The wedge-shaped male portion (7A) inserted into the (14B) is formed.
3. The pneumatic radial tire according to any one of 3. 5. A steel filler (13) having a U-shaped cross section is provided on an outer periphery of a radial carcass ply (9) folded from inside to outside around a bead core (5), and the inside of the steel filler (13) is provided. The pneumatic radial tire according to claim 1, wherein the edge height (H4) is larger than the edge height (H3) of the folded portion (9). 6. A first bead filler rubber (12A) having a substantially triangular cross section is provided on a bead core (5), and a second bead filler rubber (12B) is provided outside the filler rubber (12A). The pneumatic device according to claim 1, wherein a height (H5) of the first bead filler rubber (12A) is larger than an edge height (H3) of the folded portion (9). Radial tire. 7. The pneumatic radial tire according to claim 1, wherein claims 5 and 6 are combined.