JPH11217006A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise in a vehicle by reducing a higher-order component of a radial force variation and a tractive force variation. SOLUTION: In a pneumatic radial tire arranging a plurality of block lines 3b, 3c in which many blocks 5 are arranged in the circumferential direction of a tire on a tread surface 1, or a plurality of rib lines 3a in which many side grooves 4 are provided on a rib in the circumferential direction of the tire, the number of block lines or rib lines, having a cycle which is the minimum repetition unit in which a plurality of the blocks 5 or the side grooves 4 having a different pitch are continuously arranged, is made to differ each other every block line 3b, 3c, provided at least from the center to a shoulder end of one side, or rib line 3a.

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 having improved noise performance, and more particularly, to a method for reducing a vehicle interior noise by reducing a higher order component of a radial force variation and a tractive force variation. A pneumatic radial tire.

[0002]

2. Description of the Related Art A pneumatic radial tire has a structure that is not always uniform over the entire circumference of the tire. The force fluctuates in the direction and the front-back direction. This fluctuation in the force becomes an exciting force on the axle of the automobile, and causes the cabin noise such as a muffled sound and a beat sound.

In particular, among the measures of tire uniformity, radial force variation (RFV: fluctuation of the force in the vertical direction of the tire) and tractive force variation (TFV: fluctuation of the force in the rotation direction of the tire)
Is amplified during high-speed running and interferes with the sound of a drive system such as an engine, which may generate a large vehicle interior noise.

Therefore, it is desired to reduce the high-order components of RFV and TFV in order to further reduce the cabin noise during high-speed running.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic radial tire capable of reducing vehicle interior noise by reducing higher order components of a radial force variation and a tractive force variation. It is in.

[0006]

According to the present invention, there is provided a pneumatic radial tire according to the present invention, wherein a plurality of blocks are arranged on a tread surface in a circumferential direction of the tire or a plurality of lateral grooves are formed in ribs in the circumferential direction of the tire. In a pneumatic radial tire in which a plurality of rib rows provided with a plurality of rows are arranged, the number per block row or rib row of a minimum repeating unit in which a plurality of blocks or lateral grooves having different pitches are continuously arranged is at least a center. From one to the shoulder end of each of the block rows or rib rows.

The inventor of the present invention makes the radial force variation and the tactical force different by making the number of periods of the pitch of the block or the lateral groove different from each other at least for each block row or rib row provided from the center to one shoulder end. It has been found that higher order components of the variation can be reduced. Therefore, with the above-described configuration, it is possible to reduce vehicle interior noise caused by higher-order components of RFV and TFV.

[0008]

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 illustrates a tread pattern of a pneumatic radial tire according to an embodiment of the present invention. In the figure, tread surface 1
Are provided with a plurality of main grooves 2 extending in the tire circumferential direction and a plurality of lateral grooves 4 extending in the tire width direction. The main groove 2 and the lateral groove 4 define a rib row 3 a and a block row 3.
b, a plurality of rows of the block row 3c are divided and formed. Further, the tread patterns are shifted from each other in the tire circumferential direction on both sides of the tire equator C.

In the rib row 3a located on the center side, the lateral groove 4 crosses while leaving a part of the rib. The block row 3b located outside the rib row 3a and the block row 3c located on the shoulder side have a configuration in which a number of blocks 5 divided by the lateral grooves 4 are arranged in the tire circumferential direction. In the rib row 3a, the pitch (arrangement interval) of the lateral grooves 4 changes periodically in the tire circumferential direction.
In the block rows 3b and 3c, the pitch (arrangement interval) of the blocks 5 changes periodically in the tire circumferential direction. The blocks 5 or the lateral grooves 4 having different pitches constitute a cycle composed of the minimum repeating unit, and the number of the cycles is set to be different for each row of the rib row 3a or the block rows 3b and 3c. This cycle number must be different for each row of the rib row 3a or the block rows 3b and 3c provided at least on the tread half face from the center to one shoulder end, and further, the inner tread half face when the vehicle is mounted. The number of cycles may be different between the tread and the outer half of the tread, or the number of cycles may be different for each row of the rib row 3a or the block rows 3b and 3c over the entire tread.

For example, five types of pitches A, B, C, D,
In the case where E is set so that A becomes the maximum and gradually becomes smaller gradually to E, the pitch of at least one lateral groove 4 in the rib row 3a and the pitch of the block 5 in the block rows 3b and 3c are as shown in Table 1 below for one circumference of the tire.
It can be set as follows.

[0011]

[Table 1]

As shown in Table 1, in each row of the rib row 3a or the block rows 3b and 3c, the pitch of the lateral groove 4 or the block 5 changes in the circumferential direction of the tire, and the inflection point where the pitch changes from increasing to decreasing is determined. A period, which is the minimum repeating unit, is configured as a delimiter. That is, the pitch is as shown in FIG.
As shown in (a) and (b), it changes in three cycles in the rib row 3a, changes in four cycles in the block row 3b,
It changes in five cycles in the block row 3c.

As described above, the pitch of the block 5 or the lateral groove 4 is periodically changed in the tire circumferential direction, and the cycle number of the pitch is made different for each row of the rib row 3a or the block rows 3b and 3c. Higher order components of the radial force variation and the tractive force variation can be reduced. Therefore, these RFV
In addition, it is possible to reduce vehicle interior noise caused by higher-order components of TFV.

In the above embodiment, the case where five rib rows or block rows are provided on the tread surface has been described. However, in the present invention, the number of rib rows or block rows is not particularly limited. The present invention is also applicable to a case in which only one of a rib row and a block row is provided on the tread surface.

[0015]

EXAMPLE A tire of the present invention in which the tire size was 195 / 65R15, the total pitch number in the tire circumferential direction was 60 in the tread pattern shown in FIG. Conventional tires were manufactured in which the pitch was changed in three cycles for all rows of the block rows. In the test tire, the pitch was A = 3.
9.9 mm, B = 36.3 mm, C = 33.1 mm, D
= 30.2 mm and E = 27.3 mm.

The noise performance and the high-speed uniformity of these test tires were evaluated by the following test methods. Noise performance: Each test tire was set to an air pressure of 200 kPa, and tire noise measurement in an anechoic room was performed as a substitute for vehicle interior noise. The result is shown in FIG.

High-speed uniformity: Each test tire was mounted on a drum tester at an air pressure of 200 kPa, and a speed of 2
At 0 to 120 km / h, the fifth and sixth order components of the radial force variation and the tractive force variation were measured. Table 2 shows the evaluation results. In Table 2, the difference between the measured value of the tire according to the present invention and the measured value of the conventional tire and the reduction ratio with respect to the conventional tire are also shown.

[0018]

[Table 2]

As is clear from Table 2, the fifth and sixth order components of the TFV and RFV of the tire of the present invention were significantly reduced as compared with the conventional tire.

Further, as shown in FIG. 3, the noise level of the tire of the present invention was reduced by about 1 to 2 dB (A) as compared with the conventional tire in the entire measurement speed range (20 to 120 km / h).

[0021]

As described above, according to the present invention, a plurality of block rows in which a number of blocks are arranged on the tread surface in the circumferential direction of the tire or a plurality of horizontal rows are provided in ribs in the circumferential direction of the tire are arranged. In a pneumatic radial tire, the number of blocks per block row or rib row that is the minimum repeating unit in which a plurality of blocks or lateral grooves having different pitches are continuously arranged is provided at least from the center to one shoulder end. Since the high-order components of the radial force variation and the tactical force variation are reduced by making each of the rows or the rib rows different from each other, the vehicle interior noise caused by the high-order components of these RFV and TFV is reduced. be able to.

[Brief description of the drawings]

FIG. 1 is a development view illustrating a tread pattern of a pneumatic radial tire according to an embodiment of the present invention.

FIGS. 2 (a) and 2 (b) are development views showing one circumference of the tire of the tread pattern of FIG. 1 divided by XX line.

FIG. 3 is a diagram showing noise performance of a test tire.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tread surface 2 Main groove 3a-3c Land part 4 Side groove 5 Block C Tire equator

Claims (1)

[Claims] 1. A pneumatic radial tire having a plurality of blocks arranged on a tread surface in which a large number of blocks are arranged in a tire circumferential direction or a plurality of ribs provided with a large number of lateral grooves in a tire circumferential direction rib. The number of blocks per row or rib row, which is the minimum repeating unit in which blocks or horizontal grooves are continuously arranged, is different from each other at least for each row of block rows or rib rows provided from the center to one shoulder end. Pneumatic radial tires.