JP2001213117A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic radial tire having improved medium frequency load noises. SOLUTION: A belt cover layer 6 having steel cords (s) wound at an angle of substantially zero degree to a tire peripheral direction is provided on the outer peripheries of belt layers 5a, 5b. A distance (d) between the steel cord (s) of the belt cover layer 6 and a reinforcing cord (f) of the outsidemost layer 5b of the belt layer is 0-0.15 mm.

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.
Hz), and a pneumatic radial tire with reduced road noise.

[0002]

2. Description of the Related Art Road noise reduction is one of the measures for improving the riding comfort of passenger cars. In particular, there is a high demand for reduction of middle frequency road noise (hereinafter referred to as middle frequency road noise). Here, the road noise is a resonance sound generated by vibrations generated by the tires picking up irregularities on the road surface during high-speed traveling and resonating in the vehicle interior through the axle.

Conventionally, in a pneumatic radial tire for high-speed running, a belt cover layer in which a nylon cord is wound at substantially 0 ° with respect to the tire circumferential direction is provided on the outer peripheral side of the belt layer. Although the high-speed durability is enhanced by enhancing the tagging effect, the countermeasure also exerts the effect of reducing the intermediate frequency road noise.

However, in recent years, as passenger cars have become more sophisticated,
The reduction of road noise that can be obtained by the measures described above is not satisfied, and the reduction of high-level intermediate frequency road noise is required.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic radial tire in which intermediate frequency road noise is further reduced.

[0006]

A pneumatic radial tire according to the present invention that achieves the above object has a belt in which a steel cord is wound around the outer periphery of a belt layer at an angle of substantially 0 ° with respect to the tire circumferential direction. A cover layer is provided, and the distance between the steel cord of the belt cover layer and the reinforcing cord of the outermost layer of the belt layer is set to 0 to 0.15 mm.

As described above, instead of the nylon cord used for the conventional belt cover layer, a steel cord having a remarkably higher elastic modulus is used, and the steel cord for the belt cover layer and the reinforcing cord for the belt layer are used. The deformation mode (second section mode) in which the vibration of the tire during driving causes the tire section to vibrate in the same phase, especially the tread and sidewalls are in phase and the shoulder vibrates in opposite phase. Is suppressed, and the intermediate frequency road noise can be further reduced.

[0008]

FIG. 1 is a half sectional view showing a pneumatic radial tire according to the present invention.

In FIG. 1, a carcass layer 2 is mounted so as to extend from a tread 4 to left and right bead portions 1, 1, and both end portions in the tire width direction are turned around a bead core 3 from inside to outside of the tire. ing.

On the outer peripheral side of the carcass layer 2, two belt layers 5 in which reinforcing cords f intersect each other between the layers.
a and 5b are arranged. The cord angle of the belt layers 5a and 5b with respect to the tire circumferential direction is set in the range of 10 to 45 °, preferably 15 to 35 °. As the reinforcing cord f, a steel cord is generally used, but an organic fiber cord having a high elastic modulus such as an aromatic polyamide fiber can also be used.

On the outer peripheral side of the belt layers 5a and 5b, a belt cover layer in which a steel cord s is spirally wound at an inclination angle of substantially 0 °, more specifically 5 ° or less with respect to the tire circumferential direction. 6 are provided. The belt cover layer 6 may be in the form of an edge cover that covers only both end portions in the tire width direction of the belt layers 5a and 5b, as shown in FIG. 2, or as shown in FIG. 5b
May be in the form of a full cover that covers the entirety of.

In the above configuration, the outer peripheral side belt layer 5b
Reinforcement cord f and belt cover layer 6 steel cord s
Is set to 0 to 0.15 mm. Since the belt cover layer 6 is made of a steel cord having a large elastic modulus, the tag cover effect of the belt cover layer is further enhanced as compared with the case of the nylon cord, and the movement of the belt layer during high-speed running can be suppressed. Since the thickness d of the rubber layer is 0.15 mm or less, the vibration caused by the deformation of the cross-section secondary mode of the tire during tire running is suppressed, so that the intermediate frequency road noise is further reduced. .

The belt cover layer 6 is formed by arranging one or more steel cords s together and spirally wrapping them in the tire circumferential direction in the state of a rubber-coated strip. 0.15 thickness d
mm or less, it is desirable to minimize the amount of rubber coating on the strip or to wrap a steel cord directly on the belt without rubber coating.

The higher the elastic modulus of the steel cord s, the better for the above-mentioned reasons.
Use the above.

Here, the elastic modulus of the steel cord refers to the inclination (load / strain) of the linear portion of the load-strain curve obtained when a tensile test is performed on a steel cord collected from a tire, and the filament constituting the cord. Divided by the sum of the cross-sectional areas of Further, in order to enhance the effect of reducing the above-mentioned medium frequency road noise, the product of the cross-sectional area of the steel portion of the steel cord s constituting the belt cover layer and the number of drivings per 50 mm width is 0.4 to 1.5 mm ² /. 50
mm is preferable. The product is 1.5mm ² / 50m
If m is exceeded, the effect of reducing road noise is saturated, and the disadvantage is that the tire weight is rather increased.

In the present invention, the belt cover layer 6 of the steel cord s must be provided so as to be in contact with at least the belt layer 5b. In addition to this steel cord layer, an organic fiber cord such as nylon is further provided in the tire circumferential direction. A cover layer wound at an angle of substantially 0 ° may be used in combination.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Belt cover layers except that the tire size is 195 / 65R15, the tire structure is as shown in FIG. 1, the belt layer is made of steel cord, and the width of the belt cover layer is 30 mm are common. The pneumatic radial tires for passenger cars of Examples 1 to 3, the conventional example, and the comparative example in which the cord material, cord structure, elastic modulus, and inter-cord distance d were different as shown in Table 1 were produced.

Table 1 shows the results of measuring the medium frequency road noise at a frequency of 315 Hz for these five types of tires under the following measurement conditions.

Measuring method of medium frequency road noise: A test tire assembled into a rim with a rim size of 15 × 6JJ at an internal pressure of 210 kPa is mounted on a 2.5-liter FR car,
By driving on a road noise measuring road surface at a speed of 50 km / h, a sound collecting microphone was installed inside the window of the driver's seat to measure road noise sound pressure at a frequency of 315 Hz. The evaluation results are shown as differences using the sound pressure level of the conventional tire as a reference (0 dB). The larger the negative value, the better the effect of reducing mid-frequency road noise.

[0020]

[Table 1]

[0021]

As described above, the pneumatic radial tire of the present invention has a belt cover layer in which a steel cord is wound at an angle of substantially 0 ° with respect to the tire circumferential direction on the outer peripheral side of the belt layer. Since the distance d between the steel cord and the reinforcing cord of the outermost layer of the belt layer was set to 0 to 0.15 mm, the tightening action of the steel cord having a high modulus of elasticity and the remarkably small distance d synergistically produced a cross section of the tire. In order to reduce the vibration caused by the deformation of the second mode,
Medium frequency road noise can be further reduced.

[Brief description of the drawings]

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

FIG. 2 shows an example of a belt structure of the tire of the present invention,
(A) is an explanatory sectional view, and (b) is an explanatory plan view.

FIG. 3 shows another example of the belt structure of the tire of the present invention,
(A) is an explanatory sectional view, and (b) is an explanatory plan view.

FIG. 4 is an enlarged explanatory view of a portion surrounded by a circle X in FIG. 1;

[Explanation of symbols]

 1 bead portion 2 carcass layer 4 tread portion 5a, 5b belt layer 6 belt cover layer f reinforcing cord s steel cord

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B60C 9/20 B60C 9/20 EC

Claims (5)

[Claims] 1. A belt cover layer in which a steel cord is wound at an angle of substantially 0 ° with respect to the tire circumferential direction on the outer peripheral side of the belt layer, and the steel cord of the belt cover layer and the belt cover The distance from the outer layer reinforcement cord is 0 to
A pneumatic radial tire set to 0.15 mm. 2. The pneumatic radial tire according to claim 1, wherein the belt cover layer is arranged at least at both ends in the width direction of the belt layer. 3. The steel cord has an elastic modulus of 175 G.
The pneumatic radial tire according to claim 1, wherein the pressure is Pa or more. 4. A product of the number of implanted per 50mm wide cross-sectional area and said steel cord steel part of the steel cord according to claim 1, 2 or 3 which is 0.4 to 1.5 mm ² / 50mm Pneumatic radial tire. 5. A cover layer in which an organic fiber cord is wound at an angle of substantially 0 ° with respect to the tire circumferential direction in addition to the belt cover layer. The pneumatic radial tire according to 1.