JPH1120421A - 15× tapered radial ply tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent separation at the outer edge of a wire chafer easily generated in a 15 deg. tapered radial ply tire for a truck or a bus, for example. SOLUTION: A 15 deg. tapered radial ply tire has a pair of bead cores 2, a carcass ply 3, a wire chafer 9 having an outer edge 5 on the tire radial outside 7 of an edge position 6 of the carcass ply 3, and a nylon chafer 10 arranged from a position 11 on the tire radial outside 7 of the outer edge position 5 to a position 12 in a range where fastening force of the bead core 2 acts. A wire cord and a nylon cord respectively extended from a wire cord end position and a nylon cord end position obtained by rotatory-moving a wire cord end position of the outer edge 5 and a nylon cord end position of the outer edge 11 on the same cross section in the cross direction of the tire are both positioned on the same surface side of the cross section, and the internal surface width W of the bead core 2 is in a range of 10-20 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a bead portion provided with a wire chafer and a nylon chafer, and is assembled to a 15 ° deep rim to form a tire wheel.
For example, it relates to a 15 ° tapered radial ply tire used for trucks, buses, etc., and more specifically, effectively prevents separation at the outer edge of a wire chafer, which is likely to occur with this tire, and improves durability. Improve.

[0002]

2. Description of the Related Art Heavy-duty pneumatic radial tires used for trucks, buses, etc. are mainly of the tube type having a rim having a bead seat inclined at 5 °, such as a wide flat bottom rim, and a 15 ° deep rim. 15 °, like the bottom rim
It can be broadly classified into two types of tubeless tires that use a rim with an inclined bead seat as an applicable rim.

[0003] Although these types of tires differ in the presence or absence of a tube, there is usually no significant difference in other tire structures. For example, regarding the bead portion, both tires have the purpose of reinforcing the bead portion. It is common to arrange wire chafers and nylon chafers.

[0004]

However, even with such a bead portion in which a wire chafer and a nylon chafer are similarly arranged, a tubeless tire generally has a larger wire chaser than a tube tire. Investigation by the inventor has found that separation at the outer edge of the fur is apt to occur and the bead portion tends to have poor durability.

[0005] In order to clarify the cause of the difference in bead durability between these two types of tires, the inventor examined the deformation state of the tire under load in detail.

As a result, in the case of a tube tire, the bead core tends to float as the bead portion deforms around the rim flange at the time of load, whereas in the case of a tubeless tire, the bead core tends to float when the load is applied. It was found that the bead core tended to sink in the opposite direction.

[0007] It has been found that the difference in behavior of the bead core under such a load greatly affects the bead portion durability.

That is, in the case of a tubeless tire, the bead core sinks under a load, whereby the edge of the carcass ply is pulled inward in the tire radial direction, and accordingly, the outer edge of the wire chafer also follows. Pulling in the same direction and, in addition, synergistic action with the falling down of the tire during rolling of the tire load causes a large shear stress to be concentrated on the outer edge of the wire chafer. Separation is likely to occur at the outer edge of the substrate.

[0009] On the other hand, in the case of a tube tire, the bead core rises instead of sinking when the tire is loaded. As a result, it was found that a large concentration of shear stress that would cause separation at the outer edge of the wire chafer was unlikely to occur.

[0010] Then, the inventor has conducted intensive studies on tubeless tires (specifically, 15 ° taper radial ply tires) in order to effectively improve the bead portion durability.

As a result, the positional relationship between the edge of the carcass ply, the outer edge of the wire chafer and the outer edge of the nylon chafer is optimized, and the wire cord of the wire chafer and the nylon cord of the nylon chafer are arranged. If the relationship is optimized, and the inner edge position of the nylon chafer and the inner surface width of the bead core are optimized, separation at the outer edge of the wire chafer of a 15 ° taper radial ply tire is less likely to occur, and the bead portion It has been found that durability can be effectively improved.

An object of the present invention is to optimize the positional relationship between the edge of a carcass ply, the outer edge of a wire chafer and the outer edge of a nylon chafer, a wire cord of a wire chafer and a nylon cord of a nylon chafer. By optimizing the arrangement of the tires and by adjusting the inner edge position of the nylon chafer and the inner surface width of the bead core, it can be assembled to a 15 ° deep rim to form a tire wheel, such as a truck or bus. An object of the present invention is to effectively prevent separation at an outer edge of a wire chafer, which is likely to occur in a 15 ° tapered radial ply tire used, and to improve durability.

[0013]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a pair of bead cores each having a polygonal cross section, extending in a toroidal shape therebetween, with both ends extending from the inside to the outside of each bead core. Carcass ply turned back,
A wire chafer having an outer edge located along the outer surface of the folded portion and located radially outside the edge position of the carcass ply, and arranged along the outer surface of the wire chafer, and A nylon chafer arranged from a position radially outside the outer edge of the wire chafer in the tire radial direction to at least a position within a range in which the bead core tightening force acts on the rim, and a nylon chafer disposed outside the wire chafer. The one wire cord end position existing at the end edge and the one nylon cord end position existing at the outer end edge of the nylon chafer are rotated on the same tire width direction cross section with the tire rotation axis as the central axis. When moving, wires extending from the wire cord end position and the nylon cord end position rotated on the cross section, respectively. The yam cord and the nylon cord are both 15 ° tapered radial ply tires, wherein the inner surface width of the bead core facing the bead sheet of the rim is in the range of 10 to 20 mm, which are located on the same surface side of the cross section. .

The term "15 ° tapered radial ply tire" as used herein means a 15 ° tapered radial ply tire referred to in JATMA YEAR BOOK (1997).

Further, in the present invention, the bead core is limited to a quadrilateral or hexagonal polygon when viewed in a cross section in the tire width direction, but the “bead core inner surface width” here is specifically defined as The base length W (see FIG. 1) of the polygon (facing the base sheet of the rim) is referred to. In addition, "within the range in which the bead core tightening force acts on the rim" In the range corresponding to a width of 0.8 times the inner surface width W centered on the midpoint M of the inner surface width W.

Further, if it is necessary to further improve the durability without sacrificing other performances, the wire chafer may be composed of two or more divided chafers and / or a nylon chafer. It is preferable to dispose two or more of them.

In addition, when it is necessary to further reduce the stress concentration at the outer edge of the wire chafer, at least one nylon chafer should be moved beyond the range where the bead core tightening force acts on the rim. Further, it is preferable to further wind up and arrange the carcass ply to a position along the main body of the carcass ply.

Further, when it is necessary to further reduce the stress concentration at the outer edge of the wire chafer during rolling of a tire load and to suppress the occurrence of cracks from the outer edge, the wire chafer may be used. It is preferable that the modulus of the coating rubber constituting 100% is smaller than that of the coating rubber constituting the carcass ply by 100%.

If it is necessary to effectively reduce the growth rate of a crack generated near the outer edge of the wire chafer to further improve the durability, the wire cord of the wire chafer should be a bundle cord. Is preferred.

[0020]

FIG. 1 shows a cross section in the width direction of a bead portion of a 15 ° tapered radial ply tire according to the present invention.
In the figure, reference numeral 1 denotes a bead portion, 2 denotes a bead core, 3 denotes a carcass ply, 4 denotes a folded portion of the carcass ply, 7 denotes a tire radially outer side, 9 denotes a wire chafer, and 10 denotes a nylon chafer.

The tire having the bead portion 1 shown in FIG.
A pair of bead cores 2, and a tread extending in a toroidal shape between the bead cores 2 and reinforced with a belt (not shown) having a plurality of layers on the outer periphery of a crown portion of a carcass ply 3 whose both ends are folded back from inside to outside of each bead core 2 A wire chafer 9 and a nylon chafer 10 are sequentially arranged on the bead portion 1 along the outer surface of the folded portion 4 of the carcass ply 3.

The main features of the present invention are to optimize the positional relationship between the edge of the carcass ply, the outer edge of the wire chafer and the outer edge of the nylon chafer, the wire cord of the wire chafer and the nylon chain. An object of the present invention is to optimize the arrangement of the nylon cords of the fur and to optimize the inner edge position of the nylon chafer and the inner surface width of the bead core.

More specifically, the above-mentioned invention specific matters are as follows:
The wire chafer 9 is arranged along the outer surface of the folded portion 4 of the carcass ply 3, and the wire chafer 9 is
The outer edge 5 of the wire chafer is arranged on the outer side 7 in the tire radial direction from the edge position 6 of the carcass ply 3, and the nylon chafer 10 is arranged along the outer surface of the wire chafer 9. This means that it is arranged on the outer side 7 in the tire radial direction from the outer edge position 5, and by adopting this configuration, the shear stress that tends to concentrate on the outer edge of the wire chafer is also applied to the nylon chafer. This can reduce stress concentration at the outer edge of the wire chafer.

However, even if the above-mentioned specific features of the invention are satisfied, depending on the arrangement relationship between the wire cord of the wire chafer and the nylon cord of the nylon chafer,
The stress concentration at the outer edge of the wire chafer cannot be sufficiently reduced.

The reason is that the wire chafer and the nylon chafer are deformed with the deformation of the tire when rolling under load, but the wire chafer is easily deformed in the direction in which the wire cords are arranged. If the wire cord of the wire chafer and the nylon cord of the nylon chafer are arranged crosswise across the tire width cross section, the wire chafer moves when the tire is deformed because it is easily deformed in the arrangement direction of the cord. This is because the direction and the moving direction of the nylon chafer are greatly different, and a large shear stress is easily generated between them.

Therefore, in the present invention, in addition to the above-mentioned invention-specifying matter, the above-mentioned invention-specifying matter is required as an essential configuration. More specifically, as shown in FIG. The one wire cord end position 13a existing at the end edge 5 and the one nylon cord end position 14a existing at the outer end edge 11 of the nylon chafer 10 are connected in the same tire width direction with the tire rotation axis as the center axis. When rotating the section 15 in the directions of arrows 18 and 19, respectively,
The wire cord 13 and the nylon cord 14 extending from the wire cord end position 13b and the nylon cord end position 14b (FIG. 5 (b)) rotated upward are both located on the same surface 16 side of the cross section 15. By adopting this configuration, the nylon chafer 10 can follow and deform in the moving direction of the wire chafer 9 when the tire is deformed. As a result, the outer edge of the wire chafer 9 is 5 can be further alleviated.

The cross section 15 and the end position of the wire cord
13b and the angle of intersection of the tangent and drawn respectively to the wire cord 13 and nylon cord 14 extending from each of nylon cord end position 14b (intersection angle was measured at an acute angle side) θ _1, θ
More preferably, ₂ is in the range of 55 to 75 ° and 35 to 55 °, respectively.

Further, the inventor has conducted intensive studies to further reduce the shear stress at the outer edge 5 of the wire chafer 9, and as a result, the nylon chafer 10 exerts a tightening force of the bead core 2 on the rim. If the nylon chafer 10 does not exist within the range, the nylon chafer 10 cannot be restrained by the tightening force of the bead core. Moved in the direction in which no stress was generated, and it was found that the shear stress at the outer edge 5 of the wire chafer 9 could not be effectively reduced. Further, it was also found that a similar result occurs when the inner surface width W of the bead core 2 that exerts a substantial tightening force on the rim is too small.

Therefore, in the present invention, the above-mentioned invention-specifying items and the above-mentioned invention-specifying items are required as an essential configuration. More specifically, the inner edge of the nylon chafer 10 is formed with at least the bead core 2 with respect to the rim. It is also essential to set the bead core at the position 12 within the range where the tightening force acts and to set the inner surface width W of the bead core to a range of 10 to 20 mm. By adopting this configuration, the tightening of the bead core 2 is performed. Force can be effectively applied to the nylon chafer 10, thereby preventing the above-described movement of the nylon chafer 10 and effectively reducing the shear stress at the outer edge 5 of the wire chafer 9. be able to.

The reason why the upper limit of the inner surface width W of the bead core is limited is that if the upper limit is exceeded, it becomes difficult to assemble the rim.

From the above, the present invention has the essential features of the invention as described above, and by satisfying all of them, the outer edge of the wire chafer, which tends to occur in a 15 ° taper radial ply tire, is obtained. The separation was prevented and the durability was effectively improved.

Next, another embodiment will be described. When it is necessary to further suppress the stress concentration at the outer edge 5 of the wire chafer 9, as shown in FIG. 4, the wire chafer is divided into two or more divided chafers.
It is preferable that the structure is composed of 20, 21.

When it is necessary to further suppress the stress concentration at the outer edge 5 of the wire chafer 9 without sacrificing other performances, two or more nylon chafers 10 are provided. And / or at least one nylon chafer 10 is further moved beyond the range in which the bead core 2 clamping force acts on the rim.
(FIG. 1) is preferably wound up to a position along the main body.

If it is necessary to further reduce the stress concentration at the outer edge 5 of the wire chafer 9 during rolling of the tire load and to suppress the occurrence of cracks from the outer edge 5, the wire chafer 9 may be used. It is preferable that the coating rubber forming the fur 9 has a smaller 100% modulus than the coating rubber forming the carcass ply 3. Specifically, the difference in the 100% modulus between them is 0.6%.
More preferably, it is set to 0.9.

In addition, the outer edge 5 of the wire chafer 9
If it is necessary to further improve the durability by reducing the growth rate of cracks generated in the vicinity as much as possible, it is preferable that the wire cords 15 and 16 of the wire chafer 9 be bundled cords 25.

[0036] That is, since in the case of using a single wire cord 22 to the wire cord of the wire chafer 9 as shown in FIG. 6 (a), adjacent wires code 22a, the interval x ₁ and 22b is small, Cracks generated at one wire cord end are easily propagated to the adjacent wire cord end, and as a result,
As shown in FIG. 6 (b), a crack was easily developed along the outer edge 5 of the wire chafer 9, and the crack deteriorated the durability.

[0037] Therefore, by using the flux code 23 to the wire cord of the wire chafer 9 as shown in FIG. 7 (a), adjacent bundles code 23a, the interval x ₂ and 23b is increased,
The crack generated at one bundle cord end is difficult to propagate to the other bundle cord end adjacent thereto, and as a result, as shown in FIG. The rate of growth of the cracks along the outer edge 5 of the fur 9 is reduced, so that the durability can be further improved.

The above is only an example of the embodiment of the present invention, and various changes can be made within the scope of the claims.

[0039]

EXAMPLES Next, a 15 ° tapered radial ply tire according to the present invention was prototyped and its performance was evaluated. The prototype tire had a tire size of 11 / 70R22.5, and a hexagonal bead was used for the bead core. In addition, the numbers of the drawings schematically illustrating the bead structure of each prototype tire, the inner edge position of the wire chafer, the inner edge position of the nylon chafer, the arrangement direction of the wire cord of the wire chafer and the nylon of the nylon chafer. Table 1 shows the relationship between the arrangement direction of the cords and the inner surface width W of the bead core. As shown in FIG. 2, the edge positions of the wire chafer and the nylon chafer are located on the outer side in the tire width direction among the both end edges forming the inner surface width W of the bead core as viewed in the cross section in the tire width direction. Edge position P
From the reference line m, the radial outside 7 in the tire radial direction is defined as a positive value, and the radial inner side 8 is defined as a negative value from the reference line m.
Shown inside. The carcass is composed of one ply, the ply is a steel cord arranged in the radial direction, and the belt is composed of four steel cord rubberized layers, and the arrangement direction of the cords in each rubberized layer is , The angle to the tire equatorial plane is R20 °, R20 °, L20 °, L from the tread side
52 ° (R means rising to the right and L means rising to the left.) Other tire structures used were almost the same as those of a normal 15 ° tapered radial ply tire.

For comparison, as shown in FIG. 9, the inner edge position of the nylon chafer does not exist within the tightening range of the bead core (conventional example 1), and the conventional 5 ° taper radial ply tire (conventional example 2) A tire in which the arrangement direction of the wire cord of the wire chafer and the nylon cord of the nylon chafer are in different directions (Comparative Example 1), a tire in which the inner surface width W of the bead core is out of an appropriate range (Comparative Example 2), and A 5 ° taper radial ply tire having a bead core inner surface width W within an appropriate range (Comparative Example 3) was also prototyped and its performance was evaluated. In all the tires used in this test, the edge position of the carcass ply was +15 mm, the outer edge position of the wire chafer was +35 mm, and the outer edge position of the nylon chafer was +50 mm.

[0041]

[Table 1]

(Test Method) For each of the above test tires,
The bead durability was evaluated. The bead durability is
Fit the above tires to the compatible rims (22.5 x 7.50;
After the tire wheel assembly to the × 8.00V), the rotational speed of the wheel, tire pressure 8.5 kgf / cm ^2, under the condition of the tire load mass 5000 kg, speed 60 km / h equivalent on a rotating drum having a diameter of 1.7m , And the running distance until separation occurred in the bead portion was measured and evaluated from the measured value. Table 1 shows the evaluation results. The numerical values in Table 1 are shown as index ratios with Conventional Example 2 being 100, and the larger the value, the better.

From the results shown in Table 1, Comparative Example 1 in which at least one of the invention-specifying matters of the present invention is not appropriate
In Examples 1 to 3, the bead durability was equal to or lower than that of Conventional Examples 1 and 2, but in Examples 1 to 6, the bead durability was superior to that of Conventional Examples 1 and 2. .

[0044]

According to the present invention, it is possible to effectively prevent the separation at the outer edge of the wire chafer, which tends to occur in a conventional 15 ° tapered radial ply tire used for trucks and buses. Thus, it has become possible to provide a 15 ° tapered radial ply tire having excellent bead portion durability.

[Brief description of the drawings]

FIG. 1 is a typical sectional view of a bead portion of a 15 ° tapered radial ply tire according to the present invention.

FIG. 2 is a diagram showing another embodiment.

FIG. 3 is a diagram showing another embodiment.

FIG. 4 is a diagram showing another embodiment.

FIG. 5 is a view for showing an arrangement relationship between a wire cord 13 of the wire chafer 9 and a nylon cord 14 of the nylon chafer 10; A portion of the fur 10 is shown cut away.

FIGS. 6A and 6B are diagrams for explaining the state of crack propagation when a single wire cord 22 is used as the wire cord of the wire chafer 9;

FIGS. 7 (a) and 7 (b) are diagrams for explaining the state of crack propagation when a bundle cord 23 is used as the wire cord of the wire chafer 9. FIG.

FIG. 8 is a cross-sectional view of a bead portion of Conventional Example 2 (5 ° tapered radial ply tire).

FIG. 9 is a cross-sectional view of a bead portion of Conventional Example 1.

[Explanation of symbols]

 1 Bead portion 2 Bead core 3 Carcass ply 4 Turnback portion of carcass ply 3 5 Outer edge of wire chafer 6 Edge of carcass ply 3 7 Tire radial outside 8 Tire radial inside 9 Wire chafer 10 Nylon chafer 11 Nylon Outer edge of chafer 10 12 Inner edge of nylon chafer 10 13 Wire cord of wire chafer 9 14 Nylon cord of nylon chafer 10 15 Cross section in tire width direction 16 One surface side of cross section in tire width direction 17 Tire Other surface side of width direction section 15 18,19 Arrow 20,21 Split chafer 22,22a, 22b Single wire cord 23,23a, 23b Bundle cord

Claims (6)

[Claims] 1. A pair of bead cores each having a polygonal cross section, a carcass ply extending in a toroidal shape between the bead cores and having both ends folded from the inside to the outside of each bead core, and an outer surface of the folded portion. A wire chafer having an outer edge positioned radially outside of the edge position of the carcass ply, and an outer edge positioned along the outer surface of the wire chafer; and an outer edge position of the wire chafer A nylon chafer arranged at least from a position radially outside the tire to a position within a range in which the bead core tightening force acts on the rim, and one wire present at an outer edge of the wire chafer The position of the cord end and the position of one nylon cord at the outer edge of the nylon chafer are centered on the tire rotation axis, respectively. When rotating on the same cross section in the tire width direction, the wire cord and the nylon cord extending from the wire cord end position and the nylon cord end position rotated on the cross section respectively have the same cross section. Located on the front side, the inner surface width of the bead core facing the rim bead seat is 10 ~
A 15 ° tapered radial ply tire having a range of 20 mm. 2. The 15 ° tapered radial ply tire according to claim 1, wherein the wire chafer is composed of two or more divided chafers. 3. The 15 ° tapered radial ply tire according to claim 1, wherein two or more nylon chafers are provided. 4. The 15 ° taper according to claim 3, wherein at least one nylon chafer is wound up to a position along the body of the carcass ply beyond a range in which the bead core tightening force acts on the rim. Radial ply tire. 5. The 15 ° tapered radial ply tire according to claim 1, wherein the coating rubber constituting the wire chafer has a modulus 100% smaller than that of the coating rubber constituting the carcass ply. 6. The 15 ° tapered radial ply tire according to claim 1, wherein the wire cord of the wire chafer is a bundle cord.