JP2002356104A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic radial tire improvable in both high-speed durability and road noise without causing the increase of weight. SOLUTION: In this pneumatic radial tire, a belt layer 3 is arranged on the outer peripheral side of a carcass layer 2 of a tread part 1, and a belt edge reinforcing layer 4 with a reinforcing cord wound in the circumferential direction of the tire is disposed in the end region of the belt layer 3. The belt edge reinforcing layer 4 is arranged inside the belt layer 3 and outside the carcass layer 2, and a reinforcing cord forming the belt edge reinforcing layer 4 is monofilament m.

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, and more particularly, to a pneumatic radial tire having improved high-speed durability and road noise.

[0002]

2. Description of the Related Art In a pneumatic radial tire, a belt edge cover layer in which a reinforcing cord is continuously spirally wound in the circumferential direction of the tire is disposed on the outer peripheral side of an end portion of an outer belt layer, so that the endurance during high-speed running is provided. There are proposals for technologies that enhance the performance. The belt edge cover layer suppresses the lifting of the belt layer end caused by the centrifugal force during high-speed rotation of the tire, so that the edge separation of the belt layer is suppressed and the high-speed durability is improved.

In recent years, it has been found that by appropriately reinforcing the end portion of the belt layer, the natural frequency of the tire accompanying the deformation of the portion can be increased, and the road noise around 300 Hz can be reduced. Therefore, a technique has been proposed in which the belt edge cover layer of the above-described pneumatic radial tire has a two-layer structure to further improve high-speed durability and to improve road noise at around 300 Hz.

However, if the belt edge cover layer is formed as a two-layer structure in order to improve both high-speed durability and road noise of about 300 Hz, the weight is increased. There was a problem of doing.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic radial tire capable of improving both high-speed durability and road noise without increasing weight.

[0006]

According to the present invention for achieving the above object, a belt layer is arranged on the outer peripheral side of a carcass layer of a tread portion, and a reinforcing cord is wound around an end region of the belt layer in a tire circumferential direction. In a pneumatic radial tire provided with a belt edge reinforcement layer, the belt edge reinforcement layer is disposed inside the belt layer and outside the carcass layer,
The reinforcing cord constituting the belt edge reinforcing layer is a monofilament.

[0007] By thus forming the belt edge reinforcing layer from a monofilament having higher rigidity than the twisted cord instead of the cord having the twisted structure, a high tag at the end region of the belt layer without increasing the amount of cord used. Since the effect can be exhibited, it is possible to further suppress the lifting of the edge portion of the end portion of the belt layer due to the centrifugal force at the time of high-speed running, and it is possible to increase the natural frequency of the tire accompanying the deformation of the portion. . Therefore, it is possible to improve high-speed durability and road noise around 300 Hz without increasing the tire weight.

Further, since the belt edge reinforcing layer is disposed inside the belt layer and outside the carcass layer and is not disposed on the outer peripheral side of the end portion of the belt layer, a highly rigid monofilament is formed at the end portion of the belt layer. Since the step to be formed can be reduced, even if a monofilament having high rigidity is used, adverse effects on high-speed durability can be suppressed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a main part of a pneumatic radial tire according to the present invention, wherein 1 is a tread portion, 2 is a carcass layer, and 3 is a belt layer. A carcass layer 2 is mounted between left and right bead portions (not shown), and both ends of the carcass layer 2 are turned around the bead core (not shown) from the inside to the outside of the tire. Two belt layers 3 are arranged on the outer peripheral side of the carcass layer 2 of the tread portion 1.

The belt layer 3 is composed of a wide first belt layer 3A on the inner peripheral side and a narrow second belt layer 3 laminated on the outer peripheral side thereof.
B, a single-layer belt continuously wound spirally in the tire circumferential direction between the end 3a of the first belt layer 3A and the carcass layer 2 using the rubber-coated monofilament m as a reinforcing cord. An edge reinforcing layer 4 is provided.

The belt edge reinforcing layer 4 has an outer end 4a of 1
Extending from the edge x of the third belt layer 3A to the outside of the tire,
The winding density of the monofilament m is increased toward the outside of the tire. The monofilament m is formed in a flat cross section as shown in FIG. 2, and is arranged straight in the tire circumferential direction such that the long axis direction of the flat cross section is parallel to the surface direction of the belt layer 3. As shown in FIG. 3, the cut end m2 at both ends m1 in the longitudinal direction of the monofilament m is:
The monofilament m is formed on a slope inclined at an acute angle to the longitudinal direction.

As the monofilament m constituting the belt edge reinforcing layer 4, for example, a monofilament made of an organic fiber such as nylon or polyester can be preferably used.

As described above, the carcass layer 2 and the first belt layer 3
By arranging a belt edge reinforcing layer 4 in which a monofilament m having higher rigidity than a conventional cord having a twisted structure is continuously spirally wound in the tire circumferential direction between the end 3a of the belt A and the end 3a of the belt A, Since the edge reinforcing layer 4 can be attracted to lift the edge region of the belt layer 3 at the time of high-speed running via the adhesive layer, the edge separation can be suppressed, and the edge separation can be prevented and the rigid monofilament m can suppress the edge separation. Thus, even if the amount is small, it is possible to increase the natural frequency of the tire accompanying deformation of the portion.
Therefore, high-speed durability and 30%
Road noise around 0 Hz can be improved together.

Further, by increasing the winding density of the monofilament m toward the outside of the tire, a larger rebound effect can be exerted at the edge portion of the end portion 3X of the belt layer without unnecessarily increasing the usage of the monofilament m. Therefore, the above-described effects can be further enhanced.

A monofilament m having a flat cross section is used, and the long axis direction of the flat cross section is set to the belt layer 3.
When arranged so as to be parallel to the plane direction of, than when using a monofilament of circular cross section,
Since a higher tagging effect can be obtained while using the same amount of the monofilament m, the high-speed durability and the road noise improving effect can be further enhanced.

When the cut m2 at both ends m1 in the longitudinal direction of the monofilament m is formed on a slope inclined at an acute angle, the stress generated at the interface with the rubber at the edge of the monofilament m is dispersed to the wide cut m2. Therefore, the durability of the tire caused by the separation at the edge of the monofilament m can be improved.

In the present invention, the outer edge 4a of the belt edge reinforcing layer 4 is located at a distance of 10 from the belt edge x in the tire width direction.
It is preferred that the position be less than mm. If it is 10 mm or more, the durability in the end region of the tread portion 1 with large distortion is deteriorated. When the outer end 4a extends 10 mm or more from the belt edge x, the winding density is preferably gradually reduced from the edge x in order to avoid deterioration in durability in the end region.

It is preferable to extend the belt edge reinforcing layer 4 to the outside of the tire from the belt edge x as described above in order to enhance the effect described above. Is also good.

The winding density of the monofilament m can be in the range of 20 filaments / 50 mm to 40 filaments / 50 mm as an average density. The average winding density is 20 strands / 50mm
If it is lower, the reinforcing effect cannot be obtained.
Conversely, if it is higher than 40 filaments / 50 mm, it becomes difficult to secure a sufficient amount of rubber covering the monofilament m.

When forming the belt edge reinforcing layer 4 in the tire manufacturing process, the belt edge reinforcing layer 4 preferably increases the winding tension of the monofilament m toward the outside of the tire, thereby further enhancing the above-described effects. it can.

In the above embodiment, the belt edge reinforcing layer 4 is provided between the carcass layer 2 and the end 3a of the first belt layer 3A, but the end 3a of the first belt layer 3A is connected to the second belt layer. It may be arranged between the end 3b and the end 3b.
On the outer peripheral side of the end 3b of the second belt layer 3B, the monofilament m having high rigidity is arranged stepwise at the ends 3a and 3b of the first and second belt layers 3A and 3B, and therefore, from the viewpoint of high-speed durability. Not preferred.

The belt edge reinforcing layer 4 may have a structure in which the winding density of the above-described monofilament m is substantially constant. In the drawing, a single type of monofilament m is continuously wound. However, a plurality of different types of monofilaments m (for example, monofilaments made of nylon and monofilaments made of polyester) may be wound.

[0024]

EXAMPLE 1 The tire 1 of the present invention having a tire size common to 195 / 65R15 91H and a flat cross-section monofilament made of nylon for the belt edge reinforcing layer, and the belt of the tire 1 of the present invention having the structure shown in FIG. The tire 2 of the present invention in which the edge reinforcing layer is disposed between the ends of the first and second belt layers,
A comparative tire in which a belt edge reinforcing layer is disposed on the outer peripheral side of the end of the second belt layer in the tire 1 of the present invention, and a twisted cord of nylon multifilament yarn is replaced with the second belt layer in place of the belt edge reinforcing layer in the tire 1 of the present invention. A conventional tire 1 in which a belt edge cover layer having a one-layer structure wound around the outer peripheral portion of the end was disposed, and a conventional tire 2 in which the belt edge cover layer in the conventional tire 1 had a two-layer structure.

The test tires were subjected to evaluation tests for high-speed durability, road noise, and tire weight under the following measurement conditions, and the results shown in Table 1 were obtained.

High-speed durability According to the 2001 JATMA Yearbook, each test tire was JIS D-423 with a drum diameter of 1707 mm.
0, 10km every 30 minutes after JIS high-speed durability test
The test was continued at a rate of / hr until the tire was broken. The result was evaluated by an index value with the comparative tire being 100. The higher the value, the better the high-speed durability.

Road Noise Each test tire was mounted on an actual vehicle, and sensory evaluation was performed on five trained panelists, and the evaluation values were averaged. The result was expressed as an index value with the comparative tire as 100. The larger this value, the lower the road noise around 300 Hz.

Tire Weight The weight of each test tire was measured, and the result was evaluated as an index value with the comparative tire as 100. The larger the value, the larger the tire weight.

[0029]

[Table 1] From Table 1, it is understood that the tires 1 and 2 of the present invention can improve the high-speed durability and the road noise at around 300 Hz while maintaining the tire weight equivalent to that of the conventional tire 1 having a single-layered belt edge cover layer.

[0030]

As described above, according to the present invention, the belt edge reinforcing layer is made of a monofilament having higher rigidity than the twisted cord, instead of the twisted cord.
Since a high lugging effect can be exerted in the end region of the belt layer without increasing the amount of cord used, lifting of the edge portion of the belt layer end due to centrifugal force during high-speed running can be further suppressed. Thus, the natural frequency of the tire accompanying the deformation of the portion can be increased. Therefore, it is possible to improve high-speed durability and road noise around 300 Hz without increasing the tire weight.

Further, since the belt edge reinforcing layer is disposed inside the belt layer and outside the carcass layer and is not disposed on the outer peripheral side of the end portion of the belt layer, a highly rigid monofilament is formed at the end portion of the belt layer. Since the step to be formed can be reduced, even if a monofilament having high rigidity is used, adverse effects on high-speed durability can be suppressed.

[Brief description of the drawings]

FIG. 1 is a tire meridian sectional view showing a main part of a pneumatic radial tire of the present invention.

FIG. 2 is an enlarged sectional view of the monofilament of FIG.

3 is an enlarged view of a main part showing both longitudinal ends of a monofilament used for a belt edge reinforcing layer in FIG. 1. FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Tread part 2 Carcass layer 3 Belt layer 3A 1st belt layer 3B 2nd belt layer 3X, 3a, 3b
End 4 Belt edge reinforcing layer 4a Outer edge m Monofilament x Belt edge

Claims (4)

[Claims] 1. A pneumatic radial tire in which a belt layer is disposed on an outer peripheral side of a carcass layer in a tread portion, and a belt edge reinforcing layer in which a reinforcing cord is wound in a tire circumferential direction is disposed in an end region of the belt layer. Inside the belt layer,
A pneumatic radial tire in which the belt edge reinforcing layer is arranged outside the carcass layer, and a reinforcing cord constituting the belt edge reinforcing layer is a monofilament. 2. The pneumatic radial tire according to claim 1, wherein the winding density of the monofilament of the belt edge reinforcing layer is increased toward the outside of the tire. 3. The pneumatic radial according to claim 1, wherein the monofilament of the belt edge reinforcing layer has a flat cross section, and a long axis direction of the flat cross section is arranged to be parallel to a surface direction of the belt layer. tire. 4. The pneumatic radial according to claim 1, wherein the cut edges at both ends in the longitudinal direction of the monofilament of the belt edge reinforcing layer are formed on a slope inclined at an acute angle with respect to the longitudinal direction of the monofilament. tire.