JPH0558121A - Radial tire - Google Patents

Abstract

PURPOSE:To increase the rigidity of a bead part of a radial tire and enhance the performance of wandering phenomenon in a track. CONSTITUTION:A radial tire includes a plurality of carcass plies 3, 4 and a bead part having a bead wire 1 and bead filler 2 outside in the radial direction of the bead wire 1. One of the carcass plies 4 shall be a down-ply enclosing the outer surface of the bead filler 2, and the other carcass ply 3 is wound up around the bead wire 1 from inside to the outside and detained with the outside of the down-ply. Outside of the carcass ply 3 wound up, chafer 7 is wound up to the tire outside while enclosing the bead part from the inside, and the chafer height NOH on the outside shall be related to the tire section height H so that N0H>=0.4H, while the chafer height NIH on the inside be related as NIH<=0.6H.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial tire, and more particularly to a radial tire having improved wandering performance and suitable for small trucks.

[0002]

2. Description of the Related Art A radial tire having a plurality of carcass plies, a bead portion having a bead wire, and a bead filler radially outward of the bead wire is well known, and is widely used for small trucks.

2 to 4 are known examples of this type of radial tire. The radial tire of FIG. 2 has a bead filler (2) having a wedge-shaped cross section from the upper end of the bead wire (1).
Extends outward in the radial direction of the tire, and its upper end reaches the height of the maximum tire width (W). And there are two carcass plies, the first on the inner liner.
A ply (3) and a second ply (4) are laminated outside the first ply (3), and both carcass plies (3) and (4) are arranged along the inner surface of the bead filler (2). After coming down, it is wound up from the inside to the outside around the bead wire (1) to form a so-called turn-up ply. At this time, the rolled-up portion of the second ply (4) is locked to the outer surface of the bead filler (2), the ply end portion (5) is located near the upper end of the bead filler (2), and the first ply (3) is located. The wound-up part of the second ply contacts the outer surface of the second ply (4) and terminates on the bead filler (2) at a position (6) higher than the end (5). And further, these carcass plies (3),
The outside of the rolled-up portion of (4) is completely covered with a chafer (7) made of a material in which a nylon cord is topped with rubber. As shown, the chafer (7) has a lower end (8) at substantially the same height as the lower end of the bead wire (1) and an upper end (9) higher than the end (6) of the first ply (3). Located in position.

FIG. 3 shows another known radial tire,
It has the same two carcass plies (3) and (4), bead filler (2) and nylon chafer (7) as the tire shown in FIG. 2, but the first ply (3) has a bead filler (2). After descending along the inner surface of the bead, the bead wire (1) is wound up from the inner side to the outer side to form a turn-up ply, while the second ply (4) is a down-ply outer surface of the bead filler (2). Completely covering the remaining portion of the first ply (3) and the outer surface of the winding portion of the first ply (3), and the former winding portion is locked to the outer surface of the bead filler (2) and terminates at a relatively high position, while the latter, That is, the end of the second ply (4) is terminated at substantially the same height as the lower end of the bead wire (1). Also in this configuration, the nylon chafer (7) is arranged outside the second ply (4), and the lower end (8) thereof is at the same height as the end portion (5) of the second ply (4). And the upper end (9) has the maximum tire width (W).
It is almost the same height as.

The radial tire shown in FIG. 4 is a tire proposed by the applicant of the present invention in which the above tires are further improved. In the tire shown in FIG. 2, both ply end portions (5),
(6) but also the first ply (3) in the tire shown in FIG.
Since the end portions (6) of the bead are in contact with the outer surface of the bead filler (2) respectively, the separation at the cut end portion of the carcass cord damages the bead filler (2), which is relatively brittle, and causes the bead filler (2) to crack. In some cases, the required bead rigidity was reduced and the tire running was hindered. However, the carcass ply arrangement method was modified so that the carcass ply reaching the bead wire (1), here the second ply (4 ) Covers the outer surface of the bead filler (2) to form a down ply, and the remaining carcass ply, here the first ply (3), is wound up from the inside to the outside around the bead wire (1), and the ply end ( In 6), the down ply (4) is locked to the outer surface.

[0006]

By the way, the above-mentioned known tires, in particular, the radial tire shown in FIG. 4 has a large bead filler (2), and both sides of the bead filler (2) further have carcass plies (3), ( Since it is covered with 4), the bead rigidity is high, and although it is a radial tire, it has the advantage that it can prevent the wandering phenomenon on the rut, but it is arranged on the outside of the carcass ply. All of the nylon chafers (7) have the same upper edge as the maximum tire width,
The lower end (8) thereof has substantially the same height as the end portion (5) of the second ply (4), and is still sufficient to increase the rigidity of the bead portion,
There is room for that.

The present invention addresses the above situation and attempts to further improve the radial tire of the present applicant,
It is intended to further increase the rigidity of the bead portion in the radial tire by extending the chafer in each of the above examples and wrapping the bead portion so as to wind up the bead portion, and to further improve the wandering phenomenon in the rutted road. ..

[0008]

That is, the feature of the radial tire of the present invention that meets the above object is that it has a plurality of carcass plies, the bead portion has a bead wire, and a bead filler radially outward thereof. In a radial tire, one carcass ply reaching the bead wire covers the outer surface of the bead filler to form a down ply, and the other carcass ply is wound around the bead wire from the inside to the outside, and its end is engaged with the outside of the down ply. While stopping, a chafer is arranged on the outer side of the rolled up carcass ply, the bead portion is wrapped from the inner side and rolled up to the outside, and the chafer height NOH on the outer side is NOH ≧ NOH with respect to the tire cross-section height H. 0.
4H, the inner chafer height NIH is NIH ≦ 0.6H with respect to the tire cross-section height H. here,
For the chafer, the same nylon cord as the conventional one is usually used with nylon toppings, but it is possible to place more than one, but at least one should wrap the bead part as described above. Is. The filler height FH in the radial tire of the present invention is FH ≧ 0.5 H with respect to the tire sectional height H.
Is preferred.

[0009]

In the radial tire of the present invention, the down ply does not terminate on the outer surface of the bead filler, reaches the bead wire, and the end of the turn-up ply is located on the outer surface of the down ply. Since it does not directly contact the bead filler, the bead filler will not be damaged even if separation occurs at the cut end of the carcass ply.

Further, a chafer is arranged on the outside of the turn-up ply, and the chafer is wrapped around the bead portion so that the bead filler having a relatively high hardness is wrapped with the carcass ply and the chafer. As a result, the bead part is reliably protected, the durability is enhanced, the rigidity of the part is further enhanced, and the wandering performance is further enhanced.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of a bead portion which is a main part of a radial tire according to the present invention. A bead wire (1) is arranged on the bead portion, and a bead filler having a wedge-shaped cross section from the upper end of the wire (1). 2) extends outward in the radial direction of the tire, and its upper end reaches an upper part of the height of the tire maximum width (W), and the outermost of the two carcass plies (3) and (4) The two-ply (4) completely covers the outer surface of the bead filler (2) as a down-ply with its lower end (5) reaching the bead wire (1) part, while the other first ply (3) is the bead filler. It descends along the inner surface of (2) and is wound up from the inner side to the outer side around the bead wire (1) to form a turn-up ply, which terminates at the outer surface of the second ply (4), at a relatively high position (6). And a nylon chafer (7) formed by topping rubber on the nylon cord so as to cover the outer surface of the wound portion of the first ply (3) and a part of the outer surface of the second ply (4). Is the same as the invention according to the applicant's proposal shown in FIG. 4, and there is no particular difference.

However, according to the present invention, in the tire structure described above, the layered chafer (7) can be arranged from the inside without stopping the lower end of the chafer (7) at the end (5) of the second ply (4). The bead portion is wrapped and wound up to the outer surface side of the tire, and the end portion (10) terminates at a relatively high position inside the tire. This chafer (7)
The winding structure of No. 1 is an important feature of the present invention. At this time, the outer chafer height NOH and the inner chafer height NIH are NOH ≧ 0.
It is effective that 4 H and the latter have NIH ≦ 0.6 H. Of course, the inner and outer chafer heights are not critical and are for practical reasons. And, in this case, usually the height FH of the bead filler (2)
Is generally FH ≧ 0.5 H with respect to the tire sectional height H.

The number of chafers (7) may be one or more, but at least one is required to be wound up from the outside of the tire to the inside to wrap the bead portion.

Table 1 shows the results of comparison of the wandering performance of the radial tire according to the present invention with the known tires shown in FIGS. 2, 3 and 4. In the table, the larger the number, the better. The actual vehicle feeling evaluation was carried out on a road surface with a rut on a highway. If there are 6 points or more, it is at a level where general users do not have a problem. Also, since the camber thrust value is widely used as a bench characteristic value for evaluating the wandering performance, the values are shown at the same time.

[0016]

[Table 1]

From Table 1 above, the conventional structure is a level at which wandering occurs and causes a problem in driving, but the structure of FIG. 4 presented by the applicant of the present invention is at a level acceptable to almost all users. In particular, it can be seen that the tire of the present invention is at a level without any problem. Also,
The camber thrust value is also greatly improved as shown in Table 1.

Therefore, it can be seen that the tire of the present invention has significantly improved wandering performance as compared with the conventional tire.
Durability was also evaluated by performing a drum test, and the performance was higher than that of the conventional product, which was at a level without problems. It is considered that these are due to the higher rigidity of the bead portion due to the winding structure of the chafer.

[0019]

As described above, in the radial tire of the present invention, the outside of the bead filler is covered with the down ply and then the turn-up ply is wound up. Further, the chafer on the outside is wrapped around the bead portion and wound up from the inside to the outside of the tire. Since the chafer end height inside the bead filler and the outside chafer end are each within a specific range, the ply end does not come into direct contact with the bead filler, so the separation at the cut end of the carcass cord is prevented. Even if occurs, the bead filler will not be damaged, of course, since the bead filler is wrapped not only by the carcass ply but also by the chafer, the rigidity of the same part will be even higher,
It is possible to remarkably improve the wandering performance and the durability of the bead portion than ever before.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a bead portion that is a main part of a radial tire according to an embodiment of the present invention.

FIG. 2 is a sectional view of a bead portion of a known radial tire.

FIG. 3 is a sectional view of a bead portion of another known radial tire.

FIG. 4 is a cross-sectional view of a bead portion of a known radial tire of the applicant of the present invention.

[Explanation of symbols]

 (1) Bead wire (2) Bead filler (3) Carcass ply (first ply) (4) Carcass ply (second ply) (5) Second ply end (6) First ply end (7) Chafer (8) Lower edge of chafer (9) Upper edge of chafer (10) Rolling edge of chafer (W) Maximum tire width

Claims (1)

[Claims] 1. In a radial tire having a plurality of carcass plies, a bead wire having a bead wire, and a bead filler radially outward of the bead wire, a carcass ply reaching the bead wire covers the outer surface of the bead filler to form a down ply. Then, the other carcass ply is rolled up from the inner side to the outer side around the bead wire, the end part is locked to the outer side of the down ply, and the chafer is arranged on the outer side of the rolled up carcass ply. The bead portion is wrapped from the inner side and rolled up to the outer side of the tire. The outer chafer height NOH is NOH ≧ 0.4 H for the tire section height H, and the inner chafer height NIH is NIH ≦ 0.6 for the tire section height H. A radial tire characterized by being H.