JP2857485B2 - 15 ゜ taper tubeless tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention determines the ratio of the inner and outer rubber thicknesses at the winding end of a carcass, and comprises a steel cord inside and outside a carcass. The durability of the bead portion can be improved by providing the second reinforcing layer and regulating the height position thereof and overlapping the inner portion of the first reinforcing layer with the lower portion of the second reinforcing layer. The present invention relates to a tapered ubreless tire.

[Conventional technology]

For example, for heavy duty tires such as trucks and buses, tubeless tires that do not use tubes are becoming widespread. Such tubeless tires are tightly fitted to the rim compared to commonly used tubed tires, and when a load is applied to the tire, the bead portion is formed as shown in FIG. At a, a bending force is generated in which tension is applied inward and compressive stress is applied outward. When the carcass b receives the above-mentioned acting force, there arises a problem that the winding portion c of the carcass b is pulled out of the carcass b around the bead core d toward the main body e of the carcass b and comes out.

In order to prevent such movement of the carcass b, as shown in FIG. 5 (b), the leading end of the winding portion c of the carcass b is positioned on the bending neutral line of the bead portion a, and the organic fiber cord is placed outside the carcass b. The carcass b was reinforced by covering the outside of the carcass b with the used filler f. Further, as a prior art of a reinforcing structure of a 15 ° taper bead, there are JP-A-60-94806, JP-A-54-13108, and JP-B-60-6803. Various proposals have been made on suitable hardness and the like.

In this case, when reinforcing the winding portion of the carcass ply with only the nylon filler, the strength is insufficient with one sheet, and the desired reinforcing effect cannot be obtained. (Fig. 5a). Also, when a steel filler is used, a certain reinforcing effect can be obtained even with one sheet, and usually one sheet is arranged (Fig. 5c). The combination of two fillers and one steel filler is most often employed.

Further, according to JP-A-63-87304, a rubber stock is disposed between a carcass main body, a winding section, and a bead core, and a first reinforcing layer of a steel filler is disposed between the rubber stock and the carcass main body. In addition, a method has been proposed in which a second reinforcing layer of a steel filler is disposed inside the tire of the carcass body portion so as to overlap with the first reinforcing layer with a carcass ply interposed therebetween.

[Problems to be solved by the invention]

However, while the method of reinforcing the bead portion using only the nylon filler has an increase in weight and an increase in productivity with an increase in the number of sheets used, it also involves an increase in the thickness of the bead portion. There is a limit from the point of view.

In addition, the reinforcement of the bead portion by using the steel filler and the nylon filler as described above has a limit in improving the durability due to an increase in weight and productivity.

Furthermore, when only a steel filler is used, as described above, a certain reinforcing effect can be obtained even with one sheet, and there is no problem in terms of weight and productivity. As a result, it is difficult for the steel filler or the carcass ply to be concentrated at the winding end of the steel filler or carcass ply. is there.

Therefore, as shown in FIG. 5 (c), the height HE of the upper end SE inside the tire of the steel filler SF is increased to prevent the bead portion from falling down, so that the bead portion at the time of internal pressure filling and at the time of load is increased. The movement is suppressed to improve the durability, but this measure is also taken if the height HE of the upper terminal SE is made too high, the upper end SE of the tire inside the tire with steel filler SF
There is a risk that the crack may reach the inner liner and the air may invade to cause a failure, and there is a limit to this measure.

FIG. 5 (d) shows the reinforcing method in which the carcass main body is sandwiched from both sides with a steel filler inside the bead portion (Japanese Patent Laid-Open No. 63-87304).
In the structure shown in FIG. 5, since the wound portion c of the carcass ply is not reinforced by the steel filler, a failure due to a rim shift is likely to occur, and the structure shown in FIG.
-2 is arranged in a loop from the inside to the outside of the bead portion, so that the rim shift failure is prevented,
While the second reinforcing layer SF-2 is pulled radially downward inside the tire, the carcass ply body e adjacent thereto is pulled radially upward, so that shear strain is likely to occur at the interface between the two. As a result, a separation failure occurs between the second reinforcing layer and the carcass ply main body. The fifth
In the structure shown in FIG. 1F, rim chafing damage is easily induced on the bead base side. Further, the structure disclosed in Japanese Patent Application Laid-Open No. 60-94806 can be expected to have improved durability as compared with the related art, but the "high elastic rubber band" still cannot sufficiently suppress the expansion of the cord gap under a high load. The present invention has been achieved as a result of intensive studies to solve the above problems.

Accordingly, an object of the present invention is to improve the structure of the bead portion, thereby suppressing the bead portion from falling down during running without increasing the weight of the tire and without impairing the productivity of the tire. An object of the present invention is to provide an excellent heavy-load pneumatic tubeless radial tire capable of greatly improving the durability of a tire.

Furthermore, the reinforcing structure according to Japanese Patent Application Laid-Open No. 60-94806, the tire is accompanied by a convex deformation protruding outward in the tire axial direction from the side wall to the bead portion under load,
The upper portion of the beam undergoes bending deformation such that it overhangs the rim flange portion. At this time, the cord gap between the cords of the carcass ply body (the gap between adjacent cords) is forced to be widened. . In conjunction with this movement, the winding portion of the carcass ply and the steel filler reinforcing layer are pushed outward in the tire axial direction. In addition, since the bending is periodically repeated, the temperature of the bead increases. That is, the rubber in the bead portion is constantly exposed to dynamic and thermal fatigue.

Therefore, as a measure to prevent the cord gap of the carcass ply main body from widening and to suppress a rise in the temperature of the bead portion, a `` high elasticity rubber band '' is provided outside the carcass ply main body portion in the tire axial direction, that is, with the bead apex. A structure has been proposed which is attached to a boundary to suppress the width of the cord gap and to suppress heat generation by using a rubber layer having a small hysteresis loss in the bead apex, thereby improving the durability of the bead portion.

[Means for solving the problem]

In order to achieve the above object, the present invention relates to a tube having a base surface which is connected to a heel end and has a taper of 15 ° inward in the tire axial direction to reduce the inner diameter and has a base surface seated on a bead seat portion of a rim. A carcass having a body portion extending from the tread portion to the bead core of the bead portion through the sidewall portion and extending from the inside of the tire to the outside of the tire, and a winding portion rising up in the tire radial direction, A first reinforcing layer formed of a steel cord, wherein an inner portion provided on the bead portion and rising along the body portion of the carcass and an outer portion rising along the winding portion of the carcass are connected to each other;
A second reinforcing layer using a steel cord having a lower portion interposed between the inner portion of the reinforcing layer and the body portion of the carcass and rising from the height of the bead heel end along the body portion of the carcass inside the tire. The width (l) of the overlapping portion between the inner portion of the first reinforcing layer and the second reinforcing layer is 0.3 to less than the radial height (H3) of the tip of the second reinforcing layer from the heel end. The height (H1) of the leading end of the winding portion of the carcass from the heel end is not less than 2.7 times and not more than 4.0 times the height (HF) of the rim flange of the rim, and the first reinforcing layer The height (H2) of the tip of the inner portion from the heel end in the tire radial direction is 1.5 times or more and 2.4 times or less the height of the flange (HF), and the height of the tip of the second reinforcing layer in the radial direction from the heel end is The ratio (H3 / H1) of the height (H3) to the radial height (H1) of the tip of the winding portion of the carcass (H3 / H1) is 1.2 or more. And 1.6 or less,
And the intermediate portion rubber thickness (G1), which is the length in the direction perpendicular to the winding portion between the tip of the winding portion of the carcass and the main body portion, is at least 0.9 times the height (HF) of the rim flange and 1.1 times or less, and the intermediate rubber thickness (G1) of the intermediate rubber thickness (G1) and the outer rubber thickness which is the length in the direction perpendicular to the winding portion from the tip of the winding portion to the outer surface of the bead portion. (G2) and the ratio G1 / (G1 + G2) to 0.50 or more and 0.60 or less.

[Action]

In the bead portion, since the first reinforcing layer made of a steel cord continuously reinforces a region extending from the carcass main body portion to the outside of the carcass ply winding upper portion via the bead base portion, damage such as rim chafing occurs. Is prevented. Further, interposed between the carcass ply main body and the first reinforcing layer, along the inside of the carcass ply main body part from the height position of the bead heel, the height of the terminal H on the winding part of the carcass ply is 1.2 to 1.6 times the height H. Since the second reinforcing layer is arranged over the height H3, even if the carcass ply bends so as to overhang on the rim flange, the expansion of the space between cords is suppressed and the conventional structure Delamination due to interlaminar shear strain caused by a difference in the direction in which a force acts between the first reinforcing layer and the carcass ply main body prevents peeling damage by interposing the second reinforcing layer between the two. You. Moreover, since the first and second reinforcing layers use steel hardness, the rigidity of the reinforcing layers is increased, and the movement of the carcass can be more effectively prevented.

Further, since the height H1 of the leading end of the winding portion of the carcass is higher than the leading end of the first reinforcing layer and regulates the inner and outer rubber thicknesses G1 and G2 at the leading end of the winding portion, the bead portion is repeatedly deformed. Can effectively prevent the tip from peeling off.

Further, since the tip height H3 of the second reinforcing layer is greater than the tip height H1 of the winding portion and the ratio thereof is regulated, the tip portion of the winding portion of the carcass in the deformation of the tire by the second reinforcing layer. Movement and fall of the rolled portion can be prevented, and peeling of the leading end of the winding portion can be more effectively prevented.

As described above, by organically combining the above-described configuration of the present application, peeling of the end of the winding portion of the carcass can be prevented, and durability of the bead portion can be increased.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1 which shows a simplified 15 ° tapered tubeless tire 1 and FIG. 2 which shows a bead portion 2 in detail, a 15 ° tapered tubeless tire (hereinafter referred to as a tubeless tire) 1 has a tread portion 3 and a sidewall portion 4. A carcass 6 that turns around the bead cores 5, 5 of the pair of bead portions 2, 2, a first reinforcing layer 10 and a second reinforcing layer 11 disposed outside the carcass 6 of the bead portion 2. A reinforcing layer comprising:

The carcass 6 has carcass cords made of organic fibers such as aromatic polyamide, rayon, nylon, and polyester, metal fibers such as carbon fiber, glass fiber, or steel inclined side by side by 60 to 90 degrees with respect to the tire equator C. A radial array consisting of

In this embodiment, the inside of the tread portion 3 and the carcass 6
Outside of the tire radial direction, a plurality of belt plies 24A, 2
A belt layer 24 made of 4B is provided. Each belt ply 24
A and 24B arrange the belt cords, which are substantially the same quality as the carcass cords of the carcass 6, in a direction crossing the carcass cords of the carcass 6, and reinforce the tread portion 3.

In this embodiment, the bead apex 25 is set up from the bead core 5 outward in the tire radial direction.

The bead portion 2 has a base surface 12 having a taper of 15 degrees from the heel end J toward the inside in the tire axial direction and a reduced inner diameter, and the base surface 12 is a rim flange in contact with the outer surface of the bead portion 2. It sits on a bead seat portion 15 of a rim 14 having 13.

The carcass 6 includes a main body 7 extending from the tread portion 3 to the bead core 5 of the bead portion 3 through the sidewall portion 4.
And a winding portion 9 wound around the bead core 5 from the inside to the outside of the tire and extending outward in the tire radial direction. The height H1 of the tip of the winding portion 9 from the heel end J.
Is not less than 2.7 times and not more than 4.0 times the height HF of the rim flange 13 of the rim 14.

Each of the first reinforcing layer 10 and the second reinforcing layer 11 is formed by juxtaposing cords made of steel, and is arranged so as to cross the carcass cords of the carcass 6, thereby forming the first and second reinforcing layers. Reference numerals 10 and 11 reinforce the carcass 6 and cooperate with the carcass 6 to exert a hoop effect and increase the rigidity of the bead portion 2.

The first reinforcing layer 10 wraps the carcass 6 and
An inner portion 16 rising along the winding portion 9 and an outer portion 17 rising along the winding portion 9 are continuous, and a height H2 of the tip of the inner portion 16 from the heel end J in the tire radial direction is the flange height HF. 1.5 times or more and 2.4 times or less.

In the present embodiment, the tip of the outer portion 17 is lower than the tip of the winding portion 9 of the carcass 6 and the difference is about 5 to 15 mm.

In a conventional tire, when a reinforcing layer is provided outside the carcass, the reinforcing layer is higher than the leading end of the winding portion of the carcass, that is, the leading end of the winding portion is wrapped by the reinforcing layer. In the embodiment, the leading end of the winding portion 9 is
Is projected from the reinforcing layer 10.

The second reinforcing layer 11 rises from the height of the bead heel end J along the main body 7 of the carcass 6 and has a lower portion 19 having an overlapping portion of at least 10 mm with the inner portion 16 of the first reinforcing layer 10. Equipped.

The height H3 of the tip of the second reinforcing layer 11 from the heel end J and the height H1 of the winding portion 9 of the carcass 6 in the radial direction and the ratio H3.
/ H1 is 1.2 or more and 1.6 or less.

If the ratio H3 / H1 exceeds 1.6, the leading end of the second reinforcing layer 11 peels off before the leading end of the winding portion 9 separates. On the other hand, if the ratio is less than 1.2, peeling is likely to occur at the tip of the winding portion 9 and the durability of the bead portion 2 is not improved.

Further, the thickness of the rubber on both sides at the end of the winding portion 9 of the carcass 6 is regulated.

The intermediate portion rubber thickness G1 between the tip of the winding portion 9 and the body portion 7 in the direction orthogonal to the winding portion 9 is set to be 0.9 times or more and 1.1 times the height HF of the rim flange, and The ratio G1 / () of the intermediate rubber thickness G1 to the sum of the intermediate rubber thickness G1 and the outer rubber thickness G2 which is the length in the direction orthogonal to the winding portion 9 from the tip of the winding portion 9 to the bead outer surface 20. G1 + G
2) is set to 0.50 or more and 0.60 or less.

Therefore, the leading end of the winding portion 9 is located at a substantially middle position of the distance from the main body portion 7 of the carcass 6 to the bead portion outer surface 20, and a rubber layer having substantially the same thickness is provided on the outside of the leading end of the winding portion 9. It will intervene.

If the ratio is less than 0.50 and exceeds 0.60, peeling occurs at the leading end of the winding portion 9 and the durability of the bead portion is reduced.

In the present invention, a filler 26 made of an organic fiber cord such as a nylon cord may be provided on the outside of the first reinforcing layer 10 if necessary, as shown by a dashed line in FIG. However, the weight of the tire increases.

〔Concrete example〕

Attach a tire of size 11R22.5 to a rim of 7.50 x 22.5, apply a load of 250% of the maximum load specified in JIS under an internal pressure of 120% of the normal internal pressure, and set the rim flange to 115
The second reinforcing layer 11 is heated under a temperature of
Ratio H3 / H1 between the height H3 of the carcass and the height H1 of the tip of the winding part of the carcass
Was tested for durability. The test was performed with the ratio K between the intermediate rubber thickness G1 and (G1 + G2) being 0.6 and 0.5.

 H2 / HF = 2.0 The test results are shown graphically in FIG.

The test was conducted using an indoor durability tester, and the time until the bead portion was broken was determined.
Is indicated by an index with the conventional product of 1.0 as 100.

It was found that the larger the numerical value, the better, and that the configuration in the range of the present application is superior to the configuration outside the range.

[Specific Example 2] The intermediate rubber thickness G1 and the outer rubber thickness G2 of the intermediate rubber thickness G1 which are mounted on the same rim and the same rim as the specific example 1 and under the same test conditions as the specific example 1. And the ratio G1 /
(G1 + G2) and durability were tested.

In the test, the height ratio H3 / H1 = h was fixed at an upper level of 1.2 and 1.6, and until the bead was broken. And the H2 / H1 is 1.6 and G1 / (G1 + G
The value of 2) is shown as an index with the value of 0.7 as 100.

It was found that the larger the numerical value, the better, and that the composition range of the present application is superior to those outside the range.

Table 1 shows the durability of the bead of the tire of the present invention (Examples 1 to 4) and the tire of the present invention (Comparative Examples 1 to 10). To the exponent. 200 or more passed.

〔The invention's effect〕

As described above, the tubeless tire of the present invention is provided with first and second reinforcing layers using steel cords arranged on the outside and inside of the carcass in the bead portion, and the overlapping width of the first and second reinforcing layers. The ratio of the height of the winding portion of the carcass to the height of the second reinforcing layer, the ratio of the height of the winding portion tip and the height of the first reinforcing layer to the flange height, and Since the gist is to regulate the ratio of the outer rubber thickness, peeling at each interface of the bead portion can be prevented, and the durability of the bead portion can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention, FIG. 2 is a cross-sectional view showing the bead portion in an enlarged manner, and FIG. 3 is a graph showing the relationship between the height of the tip of the carcass winding portion and the height of the second reinforcing layer. FIG. 4 is a graph showing the relationship between the ratio of the bead durability to the ratio, and FIG. 4 is a graph showing the relationship between the inner and outer rubber thicknesses at the tip of the winding portion of the carcass and the durability of the bead portion, and FIGS. f)
FIG. 6 is a sectional view of a bead portion showing the prior art, and FIG. 6 is a sectional view showing the operation thereof. 2 ... bead part, 3 ... tread part, 4 ... side wall part, 5 ... bead core, 6 ... carcass, 7 ... body part, 9 ... winding part, 10 ... first reinforcing layer, 11 ... second reinforcing layer, 12 ... base surface, 13 ... rim flange, 14 ... rim, 15 ... bead seat part, 16 ... ... inner part, 17 ... ... outer part, 19 ... ... lower part , 20 ... Bead outer surface, G1 ... Intermediate rubber thickness, G2 ... Outer rubber thickness, H1 ... Hole end height, H2 ... Inner end height of first reinforcing layer, H3: Height of the tip of the second reinforcing layer, HF: Height of the flange.

Claims (1)

(57) [Claims] 1. A tubeless tire connected to a heel end and tapered inward in the axial direction of the tire by a taper of 15 ° to reduce the inner diameter, and having a base surface seated on a bead seat portion of a rim in the bead portion. A carcass having a main body extending from the tread portion through the sidewall portion to the bead core of the bead portion, and a winding portion wound around the bead core from the inside of the tire to the outside and rising outward in the tire radial direction, the bead portion; A first reinforcing layer using a steel cord, wherein an inner portion rising along the body portion of the carcass and an outer portion rising along the winding portion of the carcass are connected to each other; A lower part is interposed between the inner part and the carcass main body, and rises inside the tire from the height of the bead heel end along the carcass main body. And a width (l) of an overlapping portion between the inner portion of the first reinforcing layer and the second reinforcing layer is in a radial direction from a heel end of a tip of the second reinforcing layer. The height (H3) of the carcass is 0.3 to 0.5 times the height (H3), and the height (H
1) is 2.7 times or more and 4.0 times or less the height (HF) of the rim flange of the rim, and the radial height (H2) of the first reinforcing layer from the heel end of the inner end of the rim is the flange. 1.5 times or more and 2.4 times or less of the height (HF), the radial height (H3) of the tip of the second reinforcing layer from the heel end and the radial height (H1) of the tip of the winding portion of the carcass. Ratio (H3 / H
1) is not less than 1.2 and not more than 1.6, and the intermediate rubber thickness (G1), which is the length between the leading end of the carcass winding portion and the main body in the direction perpendicular to the winding portion, is defined as the thickness of the rim flange. 0.9 times or more and 1.1 times or less of the height (HF), and the intermediate rubber thickness (G1) of the intermediate rubber thickness (G1)
And the ratio G1 / (G1 + G2) to the sum of the outer rubber thickness (G2), which is the length in the direction perpendicular to the winding portion from the tip of the winding portion to the outer surface of the bead portion, is 0.50 or more and 0.60 or less. Taper Ubeless tire.