JPH0524416A - Pneumatic radial tire for passenger vehicles - Google Patents

Abstract

PURPOSE:To reduce pattern noise and low frequency noise at the time of bracing by dividing a tread surface with small lateral grooves extending in a tire width direction, dividing a block line which is formed between main grooves on the outermost side and the shoulder edge of a ground contact area with small zig-zag grooves in a prescribed width. CONSTITUTION:A block line 4 which is divided by lateral grooves 3 and small lateral grooves 5, is divided by a small zig-zag groove 6 which has its bent point around both the grooves 3 and 5, and the relation of the ground contact width C of the block line 4 and a tread pattern width W, is set as C/W=0.12-0.15. Besides, the groove width of the lateral groove 3 is set at 1.5-3.5mm, and the amplitude E of the small zig-zag groove 6 is set as E/C=0.28-0.38. Therefore, it is possible to reduce the rigidity of the block line 4 in the tire peripheral direction and width direction for improved rigidity balance and reduction in vibration and low frequency noise at the time of braking.

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 for a passenger vehicle, and more particularly to a pneumatic radial tire for a passenger vehicle that achieves both reduction of pattern noise and reduction of low frequency noise during braking.

[0002]

2. Description of the Related Art Noise generated when a tire travels on a road surface is largely influenced by a tread pattern, and is generally called pattern noise. Conventionally, as a measure for reducing the pattern noise due to the block pattern, generally, the impact sound per block is reduced by increasing the number of pitches, or the lateral groove extending in the tire width direction is thinned to the shoulder portion. Those that reduce the outflow noise of air are used. However, since the former measure reduces the block rigidity,
Another problem is that the block is easily deformed during braking, and the low-frequency sound is increased due to the vibration during the deformation.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic radial tire for a passenger vehicle that achieves both reduction of pattern noise and reduction of low frequency noise during braking.

[0004]

The present invention provides a pneumatic radial tire having three to five main grooves extending in a tire circumferential direction and a plurality of lateral grooves extending in a tire width direction on a tread surface. The blocks of the block row formed between the outermost main groove and the shoulder end portion in the contact area are divided into two by lateral narrow grooves extending in the tire width direction, and the block row is located near the lateral narrow grooves. It is divided into two by zigzag narrow grooves extending in the tire circumferential direction while bending, and the groove width of the zigzag narrow grooves is 0.5 to 1.0 mm width, and the ratio E between the amplitude E and the width C of the block row is E. / C
Is set to 0.28 to 0.38.

Thus, by dividing the block of the block row formed between the outermost main groove of the main groove and the shoulder end portion in the contact area into two by the lateral narrow groove extending in the tire width direction, By increasing the number of pitches in the tire circumferential direction, the impact noise per block is reduced,
Reduce pattern noise. Further, since the groove is divided by the lateral narrow groove, the outflow sound of the air that escapes to the shoulder portion is reduced.

Further, by dividing the block row composed of blocks which are horizontally long by the above-mentioned two divisions into two by zigzag-shaped fine grooves extending in the tire circumferential direction while bending in the vicinity of the horizontal fine grooves, the division is divided into left and right. Since the blocks are balanced by the rigidity in the tire width direction and the rigidity in the circumferential direction, it is possible to reduce the block deformation during braking and reduce the low frequency noise during braking. Further, the groove width of the zigzag-shaped fine groove is set to 0.5 to 1.0 mm, and the ratio E / C between the amplitude E and the width C of the block row is 0.28 to 0.3.
By setting it to 8, the rigidity balance of the divided blocks is further improved, and the low frequency sound during braking is further effectively reduced.

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a main portion in a contact area of one example of a tread pattern of a pneumatic tire for a passenger car according to the present invention with a half of a ground contact width. Reference numeral 1 is a tread surface having a tread contact width W, and this tread surface 1 has a linear 4
A main groove 2 of a book and a plurality of lateral grooves 3 intersecting with the main groove are formed. The block 4a forming the block row 4 between the outermost main groove 2 and the shoulder end among the four main grooves 2 is further divided into two in the tire circumferential direction by the lateral narrow groove 5 which is thinner than the lateral groove 3. ing.

As described above, the block row 4 subdivided by the lateral grooves 3 and the lateral narrow grooves 5 is further divided into two left and right by the zigzag-shaped narrow grooves 6 extending in the tire circumferential direction. The zigzag-shaped narrow groove 6 has a zigzag shape with the vicinity of the lateral groove 3 and the lateral narrow groove 5 as a bending point. In the configuration of the tread pattern described above, the ground contact width C of the block row 4 formed in the shoulder portion in the contact area is such that the ratio C / W to the tread development width W is in the range of 0.12 to 0.15, Moreover, the groove width of the lateral groove 3 is 1.5 to 3.5 mm.
It is desirable that the number of blocks divided by the lateral groove 3 be within the range of 55 to 70.
Further, it is desirable that the lateral narrow groove 5 that divides the block 4a divided by the lateral groove 3 in the tire circumferential direction is thinner than the lateral groove 3 and that the groove width is 1.2 mm or less.

By subdividing the block 4a in this way, the number of pitches in the tire circumferential direction is further increased, and the size of each block is further reduced, so that the impact noise when the block collides with the road surface is reduced. The size of the pattern noise is reduced, and the pattern noise is greatly reduced. Further, by making the horizontal narrow groove 5 thinner than the horizontal groove 3, the outflow sound of the air passing through the shoulder portion can be reduced.

The block 4a is divided into two by the lateral narrow groove 5 in the tire circumferential direction, so that the divided block becomes elongated in the tire width direction. Therefore, if the slender shape is left as it is, the rigidity difference between the tire circumferential direction rigidity and the tire width direction rigidity becomes large, and the balance is lost so that vibration due to deformation during braking is likely to occur and low frequency sound is generated. Become. However, in the above-described tread pattern according to the present invention, since the block row 4 of the shoulder portion is divided into the right and left by the zigzag-shaped narrow groove 6 extending in the tire circumferential direction, the small blocks 4b divided into the left and the right have vertical and horizontal lengths. The ratio becomes smaller, and the difference between the rigidity in the tire circumferential direction and the rigidity in the tire width direction becomes smaller. Therefore, a good rigidity balance can be obtained, and low-frequency noise due to block vibration during braking can be reduced.

In order to improve the effect of reducing the low frequency sound at the time of intimation, which is brought about by the division of the zigzag-shaped narrow groove 6, the groove width d of the zigzag-shaped narrow groove 6 is 0.5 to 1.0 mm.
And the amplitude E of the zigzag in the ratio E / C to the block width C is in the range of 0.28 to 0.38. More preferably, the position A of the amplitude center of the zigzag-shaped narrow groove 6 is set to a position of about 1/3 of the block width C from the shoulder end to the center side.

When the ratio E / C is smaller than 0.28, the low frequency sound during braking is deteriorated, and when it is larger than 0.38, the pattern noise is large. Further, if the width d of the zigzag-shaped narrow groove is smaller than 0.5 mm, the effect of reducing the low frequency noise during braking is reduced, and if it is larger than 1.0 mm, the cornering characteristics are reduced due to the decrease in lateral rigidity. Will start to decline.

[0013]

【Example】

Example 1 A pneumatic radial tire having a tire size of 215 / 65R15 and having a tread pattern shown in FIG. 4, a tread ground contact width W of 141 mm, a shoulder row block width C of 191 mm, (C / W = 0.135), the width of the lateral groove is 2.7 mm, the width of the lateral narrow groove is 1.0 mm, the number of blocks is 60, and the tire and the zigzag narrow groove are not provided. A number of tires in which the amplitude E of the zigzag-shaped narrow groove was variously made by limiting the groove width of 0.7 mm to 0.7 mm were manufactured, and the pattern noise and the low frequency sound during braking under the following conditions were measured for each tire. The measurement results are plotted in a graph as shown in FIG.

As an evaluation vehicle, an ordinary vehicle (front engine / rear drive) was used. Pattern noise: Driving at 40, 60, 80 km / h,
(However, the gear is the highest shift speed at which the vehicle can run) The sound pressure level of the vehicle interior noise caused by the tires and the feeling of the timbre were evaluated, and coasting from 100km / h to 20km / h (engine rotation in neutral gear) Feeling evaluation in (stopped) was also performed and the overall result was plotted.

Braking low frequency sound: Braking is performed by coasting from 70 km / h (neutral gear), and the low frequency sound generated at that time is evaluated as a feeling of 0.
The test is conducted at three levels of 1, 0.2, 0.3G. Figure 2
As can be seen from the above, it can be seen that both reduction of pattern noise and reduction of low frequency sound during braking are achieved in the range where the ratio E / C of the amplitude of the zigzag groove to the block width is 0.28 to 0.38.

(Example 2) Tire size is 215/65
R15 is a pneumatic radial tire having a tread pattern shown in FIG.
mm, the width C of the shoulder block row is 191 mm, (C
/W=0.135), the width of the lateral groove is 2.7 mm, the width of the lateral narrow groove is 1.0 mm, and the number of blocks is 60, which is common to the amplitude of the zigzag-shaped narrow groove. Ratio E
/ C was limited to 0.33, and a large number of tires having various groove widths of zigzag-shaped narrow grooves were manufactured, and low frequency noise during braking under the same conditions as in Example 1 and cornering power under the following conditions were produced for each of them. Was measured. The measurement results are plotted in a graph, as shown in FIG. .

Cornering power: Air pressure 20 kgf / cm
² , cornering force per 1 degree of slip angle under load of 490 kgf As can be seen from FIG. 3, the width of the zigzag-shaped narrow groove is 0.5 to
It can be seen that in the range of 1.0, the low frequency sound during braking and the cornering power are both reduced.

[0018]

As described above, according to the present invention, the blocks of the block row formed between the outermost main groove and the shoulder end portion in the contact area are divided into two by lateral narrow grooves extending in the tire width direction. By doing so, it is possible to reduce the pattern noise due to the impact sound of the block and the outflow sound of the air flowing out to the shoulder portion. Further, the block row is divided into two by zigzag-shaped narrow grooves extending in the tire circumferential direction while bending in the vicinity of the lateral narrow grooves, and the zigzag-shaped narrow grooves have a groove width of 0.5 to 1.0 mm, and The ratio E / C of the amplitude E to the width C of the block row is 0.28 to 0.3.
Since it is set to 8, it is possible to improve the rigidity balance by reducing the difference in rigidity between the tire circumferential direction and the width direction of the subdivided block, reduce vibration during braking, and reduce low frequency sound.

[Brief description of drawings]

FIG. 1 is a plan view showing a main part in a contact area of an example of a tread pattern of a pneumatic tire for passenger cars of the present invention.

FIG. 2 is a graph showing the relationship between the ratio E / C of the amplitude of a zigzag groove to the block width, pattern noise, and low frequency sound during braking.

FIG. 3 is a graph showing the relationship between the groove width of a zigzag-shaped fine groove and the low frequency sound during braking and the cornering power.

FIG. 4 is a plan view showing a tread pattern in a contact area of an example tire of the present invention.

[Explanation of symbols]

1 tread surface 2 main groove 2a outermost main groove 3 lateral groove 4 block row 4a block 5 lateral fine groove 6 zigzag fine groove C width of shoulder block row E amplitude

Claims (1)

Claims: 1. A tire having 3 to 3 extending in the tire circumferential direction on the tread surface.
In a pneumatic radial tire having five main grooves and a plurality of lateral grooves extending in the tire width direction, a block row formed between the outermost main groove of the main grooves and the shoulder end portion in the contact area. Block is divided into two by lateral narrow grooves extending in the tire width direction, and the block row is divided into two by zigzag narrow grooves extending in the tire circumferential direction while bending in the vicinity of the lateral narrow grooves. A pneumatic radial tire for a passenger vehicle having a groove width of 0.5 to 1.0 mm and a ratio E / C of the amplitude E to the width C of the block row of 0.28 to 0.38.