JPH0958229A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To greatly improve run flat durability by reducing a deflection of a side wall part and controlling the separation trouble of a reinforcing layer. SOLUTION: A plurality of carcass layers 4 are disposed inside a belt layer 7 and both ends 4a of the carcass layers are folded back from the inside of the tire to the outside via a bead core 6 provided with a bead filler 5 on the outer periphery and reinforcing liner 8 having crescent cross section is disposed inside the carcass 4 of the side wall part 3. In a pneumatic radial tire of 50% or less in flatness, a fiber reinforcing layer 15 in which fiber codes are arrnaged at a given angle such that they overlap the fiber reinforcing liner 8 in a side view is disposed between carcass layers 4 of the side wall part 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire used as a run-flat tire that enables continuous running even if the internal pressure is reduced due to puncture or the like, and more specifically, it improves run-flat durability. The present invention relates to a pneumatic radial tire.

[0002]

2. Description of the Related Art Conventionally, a reinforcing liner having a crescent-shaped cross section made of rubber is annularly arranged inside a carcass layer in a sidewall portion of a pneumatic radial tire having a low flatness ratio, thereby providing a run flat performance to the tire. It is known that it can be given. An example of such a tire is proposed in Japanese Patent Laid-Open No. 3-176213. In this tire, the rubber characteristics and arrangement of the reinforcing liner and the bead filler are specified, and the run flat performance (durability) is further enhanced.

By the way, in recent years, a tire having more excellent run-flat durability has been demanded, and as one of the measures, a proposal of a run-flat tire in which a reinforcing layer having a reinforcing cord is arranged inside the reinforcing liner is proposed. There is.
As described above, the double structure in which the reinforcing layer is provided in addition to the reinforcing liner suppresses the amount of deflection of the sidewall portion during running of the runflat and improves the runflat durability. However, during run-flat running, a large compression strain acts on the sidewall portion, so that peeling occurs between the reinforcing liner and the reinforcing layer, and the run-flat durability cannot be significantly improved.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the bending of the sidewall portion and suppress the peeling failure of the reinforcing layer, and to greatly improve the run flat durability. To provide tires.

[0005]

Means for Solving the Problems In the present invention to achieve the above object, a plurality of carcass layers are arranged inside a belt layer, and both end portions of the carcass layer are provided with a bead core having bead fillers arranged on the outer periphery thereof. In a pneumatic radial tire having a flatness of 50% or less, in which a circular reinforcing liner having a crescent-shaped cross section is arranged by folding back from the inside of the tire to the inside of the carcass layer of the sidewall portion, between the carcass layers of the sidewall portions An annular fiber reinforcing layer in which the fiber cords are arranged at a predetermined angle so as to overlap with the reinforcing liner in a side view is provided.

As described above, by providing the annular fiber reinforcing layer in which the fiber cords are arranged at a predetermined angle between the carcass layers of the sidewall portion so as to overlap with the reinforcing liner in a side view, the run with reduced air pressure due to puncture or the like. A large load acts on the sidewall during flat running,
Even if the sidewall portion is largely bent, the fiber reinforcement layer effectively supports the carcass layer in addition to the effect of the reinforcing liner, so that the large load can be supported. It can be effectively reduced. Therefore, the load on the reinforcing liner during running of the runflat is reduced, and the runflat durability can be improved.

Moreover, since the fiber reinforcing layer is provided on the outer side of the reinforcing liner, a large compressive strain is less likely to act on the fiber reinforcing layer during run-flat traveling. Since it is firmly sandwiched between the two, it is not easily peeled off, and the failure due to the fiber reinforcing layer can be suppressed, so that the run-flat durability can be greatly improved.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The configuration of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows an example of a pneumatic radial tire having an aspect ratio of 50% or less according to the present invention, where 1 is a tread portion, 2 is a bead portion, and 3 is a sidewall portion. Left and right side wall portions 3 are connected to the right and left bead portions 2 and extend on the tire outer diameter side, and a tread portion 1 extending in the tire circumferential direction is provided between the left and right side wall portions 3.

Two carcass layers 4 are provided inside the tire, and both end portions 4a of the carcass layer 4 are buried in the left and right bead portions 2, respectively. It is folded back from the inside of the tire to the outside. The outer carcass layer 4 has both end portions 4a.
Extends only to the vicinity of the boundary where the bead core 6 and the bead filler 5 come into contact with each other, while the both end portions 4a of the inner carcass layer 4 sandwich the bead filler 5 so that the outer periphery of the bead filler 5 is sandwiched. It extends outside the tire beyond the end 5a. Carcass layer 4 Outer side tread portion 1
A plurality of belt layers 7 are embedded in.

Inside the carcass layer 4 located in the sidewall portion 3, an annular reinforcing liner 8 having a crescent-shaped cross section is arranged. The outer peripheral end 8a of the reinforcing liner 8 on the tire outer diameter side is the belt layer 7 in plan view.
Of the bead filler 5 when viewed from the side.
It has been extended to overlap with. 9 is an inner liner arranged inside the tire.
The reinforcing liner 8 is arranged between the carcass layer 4 and the inner carcass layer 4.

Reference numeral 10 denotes a reinforcing layer around the bead core. The reinforcing layer 10 is interposed between the outer carcass layer 4 and the bead core 6 and extends to the bead filler 5 side. Reference numeral 11 is a reinforcing layer disposed around the bead portion, and CL is a tire center. According to the present invention, in the pneumatic tire having the above-described configuration, the annular fiber reinforcing layer 15 in which the fiber cords are arranged at a predetermined angle is provided between the carcass layers 4 in the sidewall portions 3. The fiber reinforcing layer 15 is extended such that the inner peripheral end 15b on the tire inner diameter side is located between the inner peripheral end 8b of the reinforcing liner 8 and the bead core 6, and the outer peripheral end 1 on the tire outer diameter side.
5a extends in the vicinity of the end 7a of the belt layer 7 so as to overlap with the end 7a in a plan view, and the reinforcing liner 8
It overlaps with the side view.

By arranging the fiber reinforcing layer 15 having the fiber cords arranged at a predetermined angle as described above between the carcass layers 4 of the side wall portions 3 so as to overlap the reinforcing liner 8 in a side view, a puncture or the like may occur. Even if a large load acts on the sidewall portion 3 (a large amount of vertical deflection) during run-flat running with a reduced internal pressure, the reinforcing liner 8
In addition to that, since the fiber reinforcing layer 15 is provided, the load can be supported by both of them, whereby the amount of vertical deflection of the sidewall portion 3 can be reduced,
While the durability during run-flat traveling can be improved, since the fiber reinforcing layer 15 is interposed between the carcass layers 4 outside the reinforcing liner 8, a large compressive strain is less likely to occur during run-flat traveling. , Even if it works
Since the fiber reinforcing layer 15 is not sandwiched between the carcass layers 4 and is not easily peeled off, a failure due to the fiber reinforcing layer unlike the case where the fiber reinforcing layer 15 is arranged inside the conventional reinforcing liner is less likely to occur. , Run flat Durability can be greatly improved.

The fiber reinforcing layer 15 has a structure in which the fiber cords are aligned in one direction and arranged, and the arrangement angle of the fiber cords is inclined by 20 to 70 ° with respect to the tire radial direction. This is preferable in effectively reducing the vertical deflection amount of No. 3. More preferably, it is 30 to 45 °.
The fiber material used for this fiber cord has high tensile strength (5 to 20 MPa) and high modulus (200 to 600 MPa).
(MPa) is preferably used, and examples thereof include aramid fiber.

It is possible to provide a plurality of fiber reinforcing layers 15 between the carcass layers 4 if necessary, but from the viewpoint of weight reduction, at least one layer may be provided. Although the carcass layer 4 has two layers in the above-mentioned embodiments from the viewpoint of reducing the weight of the tire, three or more layers can be provided, and when a plurality of carcass layers 4 are arranged in such a manner, the fiber reinforcing layer is provided. It is preferable to provide 15 adjacent to the innermost carcass layer.

The fiber reinforcing layer 15 has an outer peripheral end 15
Although a may be arranged in the vicinity of the belt layer end portion 7a beyond the outer peripheral end 8a of the reinforcing liner 8, it is preferable that the outer peripheral end of the reinforcing liner 8 in a side view as shown in FIG. It is preferable to set it on the outer side of the tire with respect to 8a, whereby the weight of the fiber reinforcing layer 15 can be suppressed.

The above reinforcing liner 8 and bead filler 5
For example, Japanese Patent Laid-Open No. 3-176213 proposed by the present applicant
Those disclosed in the publication can be preferably used. Immediately
The reinforcing liner 8 has a dynamic elastic modulus E at 20 ° C.^*
₂₀Is more than 16MPa, dynamic elastic modulus E at 100 ℃^*
₁₀₀And the dynamic elastic modulus E^* ₂₀Ratio E^* ₁₀₀/ E^* ₂₀Is 0.
80 or more, 100% modulus 5.8MPa or more, 10
Rubber with loss tangent (tan δ) of 0.35 or less at 0 ℃
It is composed of

The bead filler 5 has a JIS-A hardness of 60 to 60.
The height h in the tire radial direction from the rim base to the outer peripheral end 5a of the bead filler 5 is 15 to 35 mm. Needless to say, in the tire of the present invention, a known holding mechanism such as a bead portion shape and a rim structure for preventing the tire from falling off the rim even if the internal pressure of the tire is lowered is provided.

[0018]

EXAMPLE A tire of the present invention having a structure shown in FIG. 1 in which a tire size is common to 255 / 40R17 and a fiber reinforced layer is provided between carcass layers, a conventional tire 1 in which a fiber reinforced layer is not provided in FIG. 1, and In FIG. 1, a conventional tire 2 having a fiber reinforced layer arranged inside a reinforcing liner was manufactured. 1500D / 2 for the fiber cord of the fiber reinforcement layer
Aramid fiber is used, and the arrangement angle of the cord is 45 ° with respect to the tire radial direction.

Each of these test tires was subjected to an evaluation test of the amount of vertical deflection and run flat durability under the measurement conditions shown below, and the results shown in Table 1 were obtained. Vertical deflection amount Each test tire was mounted on a rim with a rim size of 17 × 9JJ (JATMA standard rim), the air pressure was set to 0 kPa, the test tire was attached to the tester, and the vertical deflection amount in the tire radial direction when a load of 4.90 kN was applied. Is measured, and the result is 1 for Conventional Tire 1
The evaluation was performed using an index value of 00. The smaller this value is, the smaller the amount of vertical deflection is. Run-flat endurance A test tire with a load of 4.90 kN and a displacement of 3000 cc was run on the same rim as above so that the tire does not fall off from the rim with an air pressure of 0 kPa. , Measure the mileage until the tire fails,
The result was evaluated by an index value with Conventional Tire 1 being 100. The larger this value, the better the run flat durability.

[0020]

[Table 1]

As can be seen from Table 1, the tire of the present invention has a small amount of vertical deflection, and the run-flat durability is significantly improved. Further, the tire size was the same as that described above, and in the above-mentioned tire of the present invention, test tires 1 to 5 in which the arrangement angles of the fiber cords with respect to the tire radial direction were changed as shown in Table 2 were manufactured.

When each of these test tires was subjected to an evaluation test of the amount of vertical deflection and run flat durability under the above-mentioned measurement conditions, the results shown in Table 2 were obtained.

[0023]

[Table 2] From Table 2, the inclination of the fiber cord with respect to the tire radial direction is 2
It can be seen that it is preferable that the angle is 0 to 70 °, preferably 30 to 45 °.

[0024]

As described above, according to the present invention, a plurality of carcass layers are arranged inside the belt layer, and both end portions of the carcass layer are arranged from the tire inner side to the outer side through the bead core having bead fillers arranged on the outer periphery. In a pneumatic radial tire having a flatness of 50% or less, in which an annular reinforcing liner having a crescent-shaped cross section is arranged inside the carcass layer of the sidewall portion, the reinforcing liner is provided between the carcass layers of the sidewall portions. Since the annular fiber reinforcing layer in which the fiber cords are arrayed at a predetermined angle so as to overlap with each other in a side view is provided, the run-flat durability is significantly improved while suppressing peeling failure of the fiber reinforcing layer. be able to.

[Brief description of drawings]

FIG. 1 is a meridian half cross-sectional view showing an example of a pneumatic tire of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 tread part 2 bead part 3 sidewall part 4 carcass layer 4a end part 5 bead filler 6 bead core 7 belt layer 7a end part 8 reinforcing liner 8a outer peripheral end 8b inner peripheral end 15 fiber reinforcing layer 15a outer peripheral end 15b inner peripheral end

Claims (6)

[Claims] 1. A carcass layer of a sidewall portion in which a plurality of carcass layers are disposed inside a belt layer, and both ends of the carcass layer are folded back from the tire inside to outside through a bead core having a bead filler disposed on the outer periphery. In a pneumatic radial tire having an annular reinforcing liner having a crescent-shaped cross section arranged inside and having a flatness of 50% or less, a carcass layer of the sidewall portion is overlapped with the reinforcing liner in a side view. Pneumatic radial tire having an annular fiber reinforcing layer in which fiber cords are arranged at a predetermined angle. 2. An outer peripheral end of the reinforcing liner extends so as to overlap an end of the belt layer in a plan view, and an inner peripheral end extends so as to overlap with the bead filler in a side view, The pneumatic radial tire according to claim 1, wherein the inner peripheral end of the fiber reinforcing layer is located between the inner peripheral end of the reinforcing liner and the bead core. 3. The fiber cord of the fiber reinforcing layer is inclined by 20 to 70 ° with respect to the tire radial direction.
The pneumatic radial tire according to 1. 4. The pneumatic radial tire according to claim 1, wherein the fiber reinforcing layer is provided adjacent to the innermost carcass layer. 5. The pneumatic radial tire according to claim 1, wherein the fiber cord of the fiber reinforcing layer is made of aramid fiber. 6. The pneumatic radial tire according to claim 1, wherein the carcass layer has two layers.