JP2001130230A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire provided with a bead portion capable of ensuring the same level strength as that in the case where a nylon chafer is used for a bead portion without impairing a priority at a cost, i.e., a merit of a rubber chafer. SOLUTION: In the pneumatic tire, a bead wire 9 is buried in a bead portion 5 and a body ply 7 of which an end side is engaged with the bead wire 9 is provided on an inner surface side D of the tire. When a distance from an intersection G of a line segment F passing through a center O of the bead wire 9 and perpendicular to radial directions C, E of the tire to an intersection H of the line segment F and a surface of an inner surface side D of the tire of the bead portion 5 is defined as Z, a dimension of Z is defined as 1.5 mm<=Z<=3.0 mm and when a bead width at a center O position of the bead wire 9 is defined as BW, a relationship of BW and Z is defined as 0.11<=Z/BW<=0.21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a pneumatic tire.

[0002]

2. Description of the Related Art Conventionally, a pneumatic tire generally includes a tread portion which comes into contact with a road surface, a shoulder portion and a sidewall portion extending from both sides of the tread portion (in the tire rotation axis direction), And a bead portion provided on the inner peripheral side in the tire radial direction of the wall portion. FIG. 3 is a cross-sectional view of the bead portion 21 and the like cut along a surface along the tire radial direction. In the drawing, reference numeral 22 denotes a sidewall portion, 23 denotes a body ply (carcass), and 24 denotes a body ply.
Is a bead filler, 25 is an inner liner, 26 is abrasion, and 27 is a bead wire.

[0003] The bead portion 21 is fitted to the rim of the wheel.
The rim fitting portion of the bead portion 21 may bend in the direction indicated by the arrow A, and the portion indicated by the arrow B in FIG. 3 may be damaged. In order to prevent this, a reinforcing member (reinforcing layer) 28 called a nylon chafer or a rubber chafer is provided on the inner side of the inner liner 25 (the side where the air of the tire is filled) in the bead portion 21. It is provided over the entire circumference in the direction.

[0004]

SUMMARY OF THE INVENTION The aforementioned reinforcing member 28
For rubber chafers with the same thickness and width, rubber chafers are cheaper, but nylon chafers are stronger than nylon chafers. Therefore, in the case where the reinforcing member 28 is provided in the bead portion 21, when a rubber chafer is used as the reinforcing member 28, there is a merit in terms of cost as compared with the case where a nylon chafer having substantially the same volume is used. Yes (cheaper)
However, there is a drawback that the bead portion 21 is easily damaged when the bead portion 21 is incorporated into the rim because the strength is inferior.

[0005] In view of the above problems, the present invention secures the same level of strength as when a nylon chafer is used in a bead portion without losing the advantage of cost, which is an advantage of a rubber chafer. An object of the present invention is to provide a pneumatic tire having a bead portion that can be formed.

[0006]

The technical measures taken by the present invention to achieve the above object are as follows: a bead wire 9 is embedded in a bead portion 5;
In a pneumatic tire provided with a body ply 7 whose end portion is engaged with a bead wire 9, the bead wire 9
From the intersection G of a line segment F passing through the center O of the tire and extending perpendicularly to the tire radial directions C and E and a surface of the body ply 7 on the tire inner surface side D, the line segment F and the tire inner surface side of the bead portion 5 Assuming that the distance to the intersection H with the surface of D is Z, the dimension of Z is 1.5 mm ≦ Z ≦ 3.0 mm, and the bead width at the center O position of the bead wire 9 is BW. B
The relationship between W and Z is 0.11 ≦ Z / BW ≦ 0.21
It is characterized by that.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a cross-sectional view of the radial tire 1 (pneumatic tire) cut along a surface along the tire radial direction. In FIG. 1, a tire 1 has a tread portion 2 that comes into contact with a road surface, and a sidewall portion 3 that forms left and right side walls.
A shoulder portion 4 between the left and right sidewall portions 3 and the tread portion 2; and a bead portion provided on the inner side C in the tire radial direction of each of the left and right sidewall portions 3 and fitted to the rim 6 of the wheel. 5 mainly.

A body ply 7 is provided on the inner surface D of the tire 1, and an inner liner 8 is provided on the inner surface D of the tire of the body ply 7. A bead wire 9 is embedded in the bead portion 5 in the tire circumferential direction, and a bead filler 10 is located in the tire radial direction on the outer side E in the tire radial direction of the bead wire 9. . Also, the end side of the body ply 7
A bead wire 9 and a bead filler 10 are wound from the bead toe 5a side to the bead heel 5b side (see FIG. 1).

The bead portion 5 is provided with an abrasion 11 made of rubber having heat resistance and abrasion resistance from the bead toe 5a to the side wall portion 3 through the bead bottom 5c and the bead heel 5b. FIG. 1 is an enlarged view of the bead portion 5. In FIG. 1, a line segment F passing through the center O of the bead wire 9 and orthogonal to the tire radial directions C and E and a tire inner surface D of the body ply 7 are shown. The dimension of the distance (gauge) Z from the intersection G with the surface to the intersection H between the line segment F and the surface of the abrasion 11 on the tire inner side D is 1.5 mm ≦ Z ≦ 3.0 mm. I have.

The bead width BW at the center O of the bead wire 9 (the distance between the intersections H and K between the line segment F and the surfaces D and J on the tire inner and outer surfaces of the bead portion 5 (ablation 11)) And the relationship between the gauge Z is 0.11 ≦ Z /
BW ≦ 0.21. Thus, the dimension of the gauge Z is set to 1.5 mm to 3.0 mm, and Z / BW is set to 0.1 mm.
By setting the ratio to 1 to 0.21, the same level of strength as when a nylon chafer is provided can be ensured, and it can be provided at a lower cost than when a nylon chafer is provided.

If the dimension of the gauge Z is less than 1.5 mm or Z / BW is less than 0.11, the bead portion 5
Is insufficient in strength, and the probability of causing damage when incorporated into the rim 6 is higher than when a nylon chafer is provided. If the dimension of the gauge Z is larger than 3.0 mm or Z / BW is a numerical value exceeding 0.11, there is a problem that cost merit is lost and a defect is easily caused in a production process. . In the present embodiment, an example in which the chafer 12 is provided on the tire inner surface D of the inner liner 8 of the bead portion 5 has been described.
In some cases, the chafer 12 is not provided in the bead portion 5. Although the bead wire has a square cross section, the bead wire has a hexagonal cross section or another cross section.

[0012]

According to the present invention, the bead wire 9 is embedded in the bead portion 5 and the tire inner surface D is
In a pneumatic tire provided with a body ply 7 whose end portion is engaged with a bead wire 9, the bead wire 9
From the intersection G of a line segment F passing through the center O of the tire and extending perpendicularly to the tire radial directions C and E and a surface of the body ply 7 on the tire inner surface side D, the line segment F and the tire inner surface side of the bead portion 5 Assuming that the distance to the intersection H with the plane of D is Z, the dimension of Z is 1.5 mm ≦ Z ≦ 3.0 mm, and the bead width at the center O position of the bead wire 9 is BW.
By setting the relationship between Z and Z to be 0.11 ≦ Z / BW ≦ 0.21, the same level of strength as when a nylon chafer is provided can be secured, and the cost can be provided at low cost.

[Brief description of the drawings]

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

FIG. 2 is a sectional view of a pneumatic tire.

FIG. 3 is a sectional view of a conventional bead portion.

[Explanation of symbols]

5 Bead 7 Body ply 9 Bead wire C Inward in tire radial direction D Tire inner surface side F Line passing through center of bead wire and orthogonal to tire radial direction G Line passing through center of bead wire and orthogonal to tire radial direction From the intersection of a line segment passing through the center of the bead wire and orthogonal to the tire radial direction and the surface of the body ply on the tire inner surface. Distance between the line passing through the tire and the line perpendicular to the tire radial direction and the surface of the bead portion on the inner side of the tire BW Bead width at the center position of the bead wire

Claims (1)

[Claims] 1. A bead wire (9) in a bead portion (5).
And a body ply (7) whose end is engaged with the bead wire (9) on the inner surface side (D) of the tire, the center of the bead wire (9) ) And a line segment (F) orthogonal to the tire radial directions (C) and (E), and an intersection (G) between the surface of the body ply (7) on the tire inner surface side (D).
, The distance from the line segment (F) to the intersection (H) between the bead portion (5) and the surface on the tire inner surface side (D) is Z,
Assuming that the dimension of Z is 1.5 mm ≦ Z ≦ 3.0 mm, and the bead width at the center (O) position of the bead wire (9) is BW, the relationship between this BW and Z is 0. 11
A pneumatic tire characterized by satisfying ≦ Z / BW ≦ 0.21.