JPH0426242Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a pneumatic radial tire that prevents bead damage. Conventionally, radial tires such as radial tires and semi-radial tires, especially radial tires for heavy loads such as radial tires for trucks and buses specified in JISD4202, have a reinforcing layer made of metal cord adjacent to the outside of the folded part of the carcass. As a result, even though the bead portion is reinforced, since it is used under severe conditions where heavy loads are applied, the bead portion is subject to large distortions and is likely to cause so-called bead damage at an early stage. For this reason, a reinforcing layer made of an organic fiber cord such as a nylon cord is used for heavy loads, but this is also not sufficient as a reinforcing structure, and the metal cord is Damage often occurs starting from the upper end of the reinforcing layer or the upper end of the folded part of the carcass ply. This idea is based on the inside of the bead in the axial direction of the tire.
A pneumatic radial that prevents bead damage by increasing the rigidity of the bead part and reducing bead damage, based on the provision of a first reinforcing layer made of a metal cord and a second reinforcing layer made of an organic fiber cord. The purpose is to provide tires. The present invention provides a reinforcing layer made of a metal cord that surrounds the folded part of the carcass and is wound from the outside of the tire to the inside of the tire. This is a pneumatic radial tire that prevents bead damage and is characterized by having a first reinforcing layer made of cords and a second reinforcing layer made of organic fiber cords. An embodiment of a pneumatic radial tire (hereinafter referred to as tire) according to the present invention that prevents bead damage will be described below with reference to the drawings. In FIGS. 1 and 2, the tire is moved from one bead portion 6 to the other bead portion (not shown) at an angle of approximately 90 degrees or 70 to 85 degrees with respect to the tire equatorial plane Y-Y.
A folded part 2 which extends from the inside to the outside and whose end is folded back around the bead core 9 from the inside to the outside.
The carcass 1 is made of a metal cord having a diameter. The folded part 2 is made of metal, which is provided with a rolled-up part that wraps the bead core 9 radially inward in the tire axial direction and surrounds the folded part 2, in a vertically extending part of the folded part 2 along the outside in the axial direction of the tire. A reinforcing layer 3 made of cord is arranged adjacently. This metal cord is 15 to 30 mm in the circumferential direction of the tire.
arranged at an angle of
The height HR from the bead baseline L is the second
As shown in the figure, the upper end P- of the folded part 2 of the carcass 1
The height of E is set smaller than HP. Note that, as shown in FIG. 3, the height HR can also be set larger than the height HP of the upper end PE of the folded portion 2. Note that in this specification, the height hereafter refers to the distance in the radial direction from the bead base line L, as described above. As shown in FIGS. 2 and 3, the reinforcing layer 3 has an upper end 3-E of the winding portion terminated at a height h1 of 14 to 28% of the cross-sectional height H of the tire. If the height h1 of the reinforcing layer 3 inside the tire is smaller than 14% of the cross-sectional height H of the tire, the lateral rigidity of the bead portion will be insufficient and carcass damage will likely occur. or
If it is larger than 28%, the upper end 3-E will be located close to the maximum width part of the tire where the deflection is large, so delamination will occur at the upper end 3-E where the adhesive strength is poor. Note that when the tire usage conditions become higher internal pressure and load, the upper end 3-E is moved to 14 of the tire cross-sectional height H.
Even if it is located in the range of ~28%, delamination may occur at this upper end 3-E. For this reason, adjacent to the inner side of the winding part in the tire axial direction, so as to protect the upper end 3-E of the reinforcing layer 3,
A first auxiliary layer 11 made of a metal cord having a height h2 whose upper end 11-E exceeds the upper end 3-E of the reinforcing layer 3 in the radial direction is provided. Note that the metal cords of the first auxiliary layer 11 are inclined in a direction that intersects with the cords of the reinforcing layer 3 or in the same direction. Further, on the inside of the first auxiliary layer 11 in the tire axial direction, an upper end 12-E has a height h3 exceeding the upper end 11-E of the first auxiliary layer 11 in the radial direction. A second auxiliary layer 12 made of an organic fiber cord such as a nylon cord is provided to protect E. Note that the direction of the cords is inclined in a direction that intersects with the cords of the first auxiliary layer 11 or in the same direction. The height h2 of the second auxiliary layer 11 is greater than the height h1 of the winding portion (h2>h1). Thereby, the upper end 1 of the first auxiliary layer 11 of the metal cord
By making the height h2 of the reinforcing layer 3 higher than the height h1 of the upper end 3-E of the reinforcing layer 3, the upper end 3-E of the reinforcing layer 3 can be protected. Further, the height h3 of the second auxiliary layer 12 is 0.35 times or less of the tire cross-sectional height H, and the height h3 of the second auxiliary layer 12 is 0.35 times or less
(0.35H≧h3>
h2). In addition, a second cord made of organic fiber cord with low elastic modulus
By making the height h3 of the auxiliary layer 12 larger than h2, delamination of the upper end 11-E of the first auxiliary layer 11 can be prevented. Furthermore, by setting the height h3 of the second auxiliary layer 12 to 35% or less of the tire cross-sectional height H, the sidewall portion 7 where the end of the organic fiber cord is severely bent when it is greater than 0.35H.
This prevents the tire from being located near the maximum width of the tire and eliminates the causes of delamination. Furthermore, the buttrest part 1 above the sidewall part 7
A belt layer 5 is disposed in the tread portion 8 connected to the tire 0, adjacent to the outside in the radial direction of the carcass 1, and this belt layer 5 is arranged at an angle of 10 with respect to the tire equatorial plane Y-Y.
The truss structure is composed of a plurality of plies of metal cords arranged at an angle of ~70 degrees, preferably three layers of belt ply cords. [Example] Test tires were sampled with the specifications shown in Table 1, and compared with conventional products, and the bead durability test results shown in Table 1 were obtained. All specifications other than those shown in Table 1 are the same. In this way, the tire of the present invention has a taper at the bead.

[Table] Row test. Running time after bead damage is displayed as an index.
By arranging the first and second auxiliary layers,
The lateral rigidity of the bead part is improved, and stress concentration at the upper end of the reinforcing layer and carcass folding part can be suppressed, reducing crack damage and peeling of the rubber and cord at the upper end of the reinforcing layer and the upper end of the carcass. The durability of the bead portion can be improved.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing an embodiment of the tire of the present invention, and Fig. 2 shows an example of a bead portion with a high turn nap structure in which the folded portion of the carcass ply ends at a higher position than the upper end of the reinforcing layer. FIG. 3 is an enlarged sectional view illustrating a bead portion of a low turn nap structure in which the height of the folded portion of the carcass ply ends at a position lower than the upper end of the reinforcing layer. DESCRIPTION OF SYMBOLS 1... Carcass, 2... Turned part, 3... Reinforcement layer, 5... Belt layer, 6... Bead part, 8... Treaded part, 9... Bead wire, 10... Buttress part, 11... first auxiliary layer, 12...second
Auxiliary layer, P-E...terminal on carcass ply, 1
1-E...Top end of the first auxiliary layer, 12-E...Top end of the second auxiliary layer, h1...Height of the winding part of the reinforcing layer, h2...Height of the first auxiliary layer , h3...height of the second auxiliary layer.

Claims (1)

[Claims for Utility Model Registration] A metal cord that wraps both ends of a radially arranged metal cord around the bead core of a bead portion from the inside to the outside in the axial direction of the tire, surrounding the folded part of the carcass, and winding it from the outside to the inside of the tire. In a pneumatic radial tire having a reinforcing layer, the reinforcing layer has an upper end extending beyond the upper end of the winding part in the radial direction on the inner side of the winding part on the inside of the winding part in the axial direction of the tire, and a lower end thereof. a first auxiliary layer consisting of a metal cord extending to the bottom of the bead; and a first auxiliary layer disposed axially inwardly of the first auxiliary layer and having an upper end extending beyond the upper end of the first auxiliary layer radially outward. A pneumatic radial tire that prevents bead damage, characterized in that the lower end extends to the bottom of the bead part and a second auxiliary layer made of organic fiber cord is disposed.