JP6010884B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire that suppresses air column resonance without impairing wet performance.

Conventionally, a plurality of main grooves extending in the tire circumferential direction are provided on a tread surface of a pneumatic tire. The main groove is provided to remove water adhering to the tread surface and keep the tread surface and road surface in close contact with each other during rainy weather. Wet performance such as braking performance is improved.
On the other hand, there is a demand for a reduction in tire passing noise in accordance with recent upgrades and higher performance of vehicles.
One of the major factors of tire passing noise is air column resonance generated in the air column formed by the road surface and the main groove.
Conventionally, a technique has been proposed in which protrusions are arranged on the bottom surface of the main groove or the wall surface of the main groove to suppress air column resonance and reduce the passing noise of the tire (Patent Document 1).

JP-A-11-105511

However, when the protrusions are arranged on the bottom surface of the main groove or the wall surface of the main groove, depending on the size and shape of the protrusion, the drainage of the main groove is impaired, and there is a problem that affects the wet performance.
The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a pneumatic tire that suppresses air column resonance noise without impairing wet performance.

In order to achieve the above object, according to the present invention, a main groove extending in the tire circumferential direction with a width Rw is provided on a tread surface, and the tire communicates with the main groove at a plurality of positions spaced in the tire circumferential direction. A pneumatic tire is provided with a plurality of lug grooves extending outward in the width direction, and the rotation direction of the tire is specified, and a side portion of the main groove on the inner side in the tire width direction extends in the tire circumferential direction. The side surface of the main groove in the tire width direction outer side is formed by a wall surface facing the wall surface of the ribs of the plurality of blocks arranged at intervals in the tire circumferential direction, The plurality of lug grooves are formed between the wall surfaces of the blocks adjacent to each other in the tire circumferential direction, and are opposed to the wall surfaces of the ribs of one block for each of the plurality of blocks arranged at intervals in the tire circumferential direction. The wall surface is formed as a narrow main groove wall surface located at a position where the full length portion extending in the tire circumferential direction is shifted to the rib side as compared with the wall surface of the other block facing the wall surface of the rib. The narrow main groove portion having a width Rn smaller than the width Rw at a plurality of positions spaced in the extending direction of the main groove includes the narrow main groove portion wall surface and the narrow main groove portion. Formed between the wall surface of the rib facing the wall surface for use, and on both sides of the narrow main groove portion in the extending direction of the main groove, on the side portion of the narrow main groove portion on the ground contact end side, A drainage lateral groove that communicates with the main groove and extends outward in the tire width direction is provided, and the drainage lateral groove is one of the plurality of lug grooves, as compared to the width Ln of the other lug grooves. It is formed as a wide lug grooves having a width Lw of the large dimensions, the narrow main groove wall face is formed The wide inner part of the tire width direction on the wall surface forming the lug grooves of the blocks protrude at an acute angle in the rotational direction of the narrow main groove wall face and the tire to the main groove, the narrow main The groove portion has the width Rn and extends over a full length portion extending in the tire circumferential direction of the wall surface for the narrow main groove portion of the block.

According to the present invention, the narrow main groove portions are provided at a plurality of positions spaced in the extending direction of the main groove, which is advantageous in suppressing air column resonance noise.
In addition, because the drainage lateral groove is provided on the side of the narrow main groove, the water flowing through the main groove when running on a wet road surface is the same as the water flowing through the narrow main groove in the narrow main groove. Since it flows smoothly divided into the water flowing through the lateral groove, it is advantageous in maintaining wet performance.
Therefore, according to the present invention, it is advantageous in achieving both suppression of air column resonance and maintenance of wet performance.

It is a development view of a tread pattern. It is an enlarged view of the principal part of a tread pattern. It is the figure which showed the test result of the Example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the pneumatic tire 10 is a tire in which the rotation direction is specified, and the tread pattern formed on the tread surface 12 is a directional pattern. In FIG. 1, C indicates a tire equator, TW indicates a tread contact width, and an arrow X indicates a rotation direction of the tire during traveling.
More specifically, the tread surface 12 of the pneumatic tire 10 is provided with center main grooves 14 extending in the tire circumferential direction on both sides of the tire equator C, and extends in the tire circumferential direction outside the center main grooves 14. Shoulder main grooves 16 are provided, and vertical narrow grooves 18 extending in the tire circumferential direction are provided between the center main grooves 14 and the shoulder main grooves 16.
Also, a lug groove 20 is provided extending from the center main groove 14 at a position spaced in the tire circumferential direction toward the outer side in the tire width direction while being displaced rearward in the tire rotation direction. The lug groove 20 is a shoulder main groove. 16 is communicated.

The tread surface 12 is provided with a center rib 22 extending on the tire equator C between the two center main grooves 14.
Further, a block row 24 extending in the tire circumferential direction is provided between each center main groove 14 and shoulder main groove 16.
The block row 24 is defined by an inner block 26 which is defined by the center main groove 14, the lug groove 20, and the vertical narrow groove 18, and is formed by the shoulder main groove 16, the lug groove 20, and the vertical narrow groove 18. The outer blocks 28 on the outer side in the tire width direction are arranged in the tire circumferential direction.
A shoulder rib 30 extending in the tire circumferential direction is provided on the outer side of each shoulder main groove 16 in the tire width direction, and the shoulder rib 30 is a lug that communicates with the shoulder main groove 16 and extends outward in the tire width direction. A plurality of grooves 3002 are provided at intervals in the tire circumferential direction.

In the present embodiment, the present invention is applied to the center main grooves 14 on both sides of the center rib 22.
That is, narrow main groove portions 32 in which the width of the center main groove 14 is narrower than those of the other center main grooves 14 are provided at a plurality of positions spaced in the extending direction of the center main groove 14.
In the present embodiment, the narrow main groove portions 32 respectively provided in the center main grooves 14 on both sides of the center rib 22 are provided at locations that are out of phase with each other in the tire circumferential direction.
Out of both side portions of the narrow main groove portion 32 in the extending direction of each center main groove 14, the side portion of the narrow main groove portion 32 on the front contact end side communicates with the center main groove 14 and extends outward in the tire width direction. A draining lateral groove 34 is provided.
The drainage lateral groove 34 is one of the plurality of lug grooves 20 and is formed as a wide lug groove 36 having a larger width than the other lug grooves 20.

More specifically, as shown in FIG. 2, the side portion of the center main groove 14 on the inner side in the tire width direction in the width direction of the center main groove 14 is formed by the wall surface 2202 of the center rib 22 extending in the tire circumferential direction. ing.
The side portions of the center main groove 14 on the outer side in the tire width direction in the width direction of the center main groove 14 are arranged by the wall surfaces 2602 of the plurality of inner blocks 26 arranged at intervals in the tire circumferential direction and facing the wall surfaces 2202 of the center rib 22. Is formed.
The lug grooves 20 including the wide lug grooves 36 are formed between the wall surfaces of the inner blocks 26 and the wall surfaces of the outer blocks 28 that are adjacent to each other in the tire circumferential direction.
One inner block 26 protrudes toward the center rib 22 for each of the plurality of inner blocks 26 arranged at intervals in the tire circumferential direction. That is, the wall surface 2602 facing the wall surface 2202 of the center rib 22 of one inner block 26 for each of the plurality of inner blocks 26 arranged at intervals in the tire circumferential direction is the other wall surface 2602 facing the wall surface 2202 of the center rib 22. It is formed as a narrow main groove wall surface 2602 </ b> A located at a position displaced toward the center rib 22 as compared with the wall surface 2602 of the inner block 26.
The narrow main groove portion 32 is formed between the narrow main groove wall surface 2602A and the wall surface 2202 of the center rib 22 facing the narrow main groove wall surface 2602A.

According to the present embodiment, the narrow main groove portions 32 are provided at a plurality of positions spaced in the extending direction of the center main groove 14, which is advantageous in suppressing air column resonance noise.
Further, since the wide lug groove 36 is provided in the side portion of the narrow main groove portion 32 on the front contact end side, the water flowing in the center main groove 14 (arrow A) as shown in FIG. 2 when traveling on a wet road surface. Is smoothly separated into water flowing in the narrow main groove portion 32 (arrow B) and water flowing in the wide lug groove 36 (arrow C) in the upstream portion of the narrow main groove portion 32. This is advantageous for achieving both suppression of wetness and maintenance of wet performance.
In this case, the wide lug groove 36 is formed into the cross-sectional area of the center main groove 14 cut along a plane orthogonal to the extending direction of the center main groove 14 and the cross-sectional area obtained by cutting the narrow main groove portion 32 along the plane. If the cross-sectional area obtained by adding the cross-sectional area of the wide lug groove 36 cut along a plane orthogonal to the extending direction of the narrow main groove part 32 is equal to the upstream side of the narrow main groove part 32. Since the groove volume is maintained at the same level with the portion of, the water branching indicated by arrows A, B, and C is performed more smoothly, and in order to achieve both suppression of air column resonance noise and maintenance of wet performance More advantageous.
Further, in the present embodiment, the narrow main groove portions 32 respectively provided in the center main grooves 14 on both sides of the center rib 22 are provided at locations that are out of phase with each other in the tire circumferential direction. This makes it more advantageous to suppress the air column resonance by changing the length of the air column formed between the road surface and the road surface.

As shown in FIG. 2, the width of the center main groove 14 in the narrow main groove portion 32 is Rn, the width of the center main groove 14 excluding the narrow main groove portion 32 is uniform and the width is Rw, and the wide lug groove 36 is formed. And the width of the remaining lug groove 20 excluding the wide lug groove 36 is uniform and the width is Ln, and k is a coefficient of 0.9 ≦ k ≦ 1.1, Rw × Ln = It is preferable that the relational expression k · (Rn × Lw) is satisfied.
When the above relational expression is satisfied, the groove volume is maintained at substantially the same level on the upstream side of the narrow main groove portion 32 and the narrow main groove portion 32, so that suppression of air column resonance noise and wet performance are achieved. This is more advantageous in achieving both maintenance.

Further, the width of the center main groove 14 in the narrow main groove portion 32 is Rn, the width of the center main groove 14 excluding the narrow main groove portion 32 is uniform, the width is Rw, and the ratio of Rw / Rn is A. In this case, it is preferable that the relational expression of 2.0 ≦ A ≦ 5.0 is satisfied.
This is because when the ratio A of Rw / Rn is larger than 2, it is advantageous in suppressing air column resonance.
Further, if the ratio A of Rw / Rn is smaller than 5, it is advantageous for maintaining the wet performance.

Further, when the width of the wide lug groove 36 is Lw, the width of the remaining lug groove 20 excluding the wide lug groove 36 is uniform and the width is Ln, and the ratio of Lw / Ln is B, 2.0 ≦ It is preferable that the relational expression of B ≦ 5.0 is satisfied.
This is because when the ratio B of Lw / Ln is larger than 2, it is advantageous for maintaining the wet performance.
Further, if the ratio B of Lw / Ln is smaller than 5, it is advantageous for suppressing air column resonance.

(Example)
An evaluation test of wet performance and passing noise of the pneumatic tire 10 including the narrow main groove portion 32 and the wide lug groove 36 of the present invention was performed under the following conditions.
A tire having the tread pattern of FIG. 1 and having the specifications shown in FIG. 3 was prototyped. The conventional tire is a tire that does not include the narrow main groove portion 32 and the wide lug groove 36.
The center main groove 14 had a depth of 8.0 mm, and the lug groove 20 had a depth of 8.0 mm.
The tire size was 205 / 55R16, mounted on a 16 × 7 JJ wheel, and the air pressure was 210 kPa.
[Wet performance]
A wet road surface with an average depth of water of 4 mm was run on a circumference with a radius of 30 m while increasing the speed, and the generation rate of hydro was measured. The evaluation is indicated by an index with the measured value of the conventional tire as 100, and the larger the index value, the better the wet performance.
[Passing noise]
It traveled on the paved road surface at a speed of 60 km / h, and the sound pressure level was measured with a microphone attached to the window side portion of the driver's seat. The evaluation is indicated by an index with the measured value of the conventional tire as 100, and the larger the index value, the lower the noise.

From Example 1, it is clear that when the coefficient k is 0.9, the wet performance can be ensured similarly to the conventional tire, but the effect of reducing noise is reduced.
From Example 5, it is clear that when the coefficient k is 1.1, the wet performance is slightly lower than that of the conventional tire, but the effect of noise reduction is increased.
Therefore, the coefficient k is between 0.9 and 1.1 from Examples 1 to 5, and the ratio A (Rw / Rn) of the width Rw of the center main groove 14 to the width Rn of the narrow main groove portion 32 is 2. When the ratio B (Lw / Ln) of the width Lw of the wide lug groove 36 to the width Ln of the lug groove 20 is between 2.0 and 5.0, the wet performance is between 0 and 5.0. It is clear that the effect of noise reduction is exhibited while securing the same as in the conventional tire.

In the present embodiment, one inner block 26 is protruded toward the center rib 22 for each of the plurality of inner blocks 26 arranged at intervals in the tire circumferential direction, and the protruded narrow main groove wall surface 2602A. Although the case where the narrow main groove portion 32 is formed is described, the wall surface 2202 of the center rib 22 is protruded, or both the wall surface 2202 of the center rib 22 and the wall surface 2602 of the inner block 26 are protruded. Of course, 32 may be formed.
In the present embodiment, the case of having the lug groove 20 communicating with the center main groove 14 has been described, but the present invention is naturally applicable to the center main groove 14 not having the lug groove 20.
Further, in the present embodiment, the case of the pneumatic tire 10 in which the rotation direction of the tire is specified has been described. However, in the pneumatic tire in which the rotation direction of the tire is not specified, the width in the extending direction of the center main groove 14 is narrow. If the lateral grooves 34 for drainage that communicate with the center main groove 14 and extend outward in the tire width direction are provided on both sides of the main groove 32, the same effects as in the embodiment can be obtained.
The main groove to which the present invention is applied is not limited to the center main groove 14 and the shoulder main groove 16, and is widely applied to various main grooves extending in the tire circumferential direction.

  DESCRIPTION OF SYMBOLS 10 ... Pneumatic tire, 12 ... Tread surface, 14 ... Center main groove, 16 ... Shoulder main groove, 18 ... Longitudinal groove, 20 ... Lug groove, 22 ... Center rib, 2202 ... Center Rib wall surface, 24 ...... Block row, 26 ... Inner block, 2602 ... Inner block wall surface, 2602A ... Narrow main groove wall surface, 28 ... Outer block, 30 ... Shoulder rib, 32 ... Width Narrow main groove, 34 …… Drain side groove, 36 …… Wide lug groove.

Claims (5)

A main groove extending in the tire circumferential direction with a width Rw is provided on the tread surface, and a plurality of grooves extending in the tire width direction are communicated with the main groove at a plurality of positions spaced in the tire circumferential direction. The pneumatic tire is provided with a lug groove and the direction of rotation of the tire is specified,
The inner side of the main groove in the tire width direction is formed by a wall surface of a rib extending in the tire circumferential direction,
A side portion on the outer side in the tire width direction of the main groove is formed by a wall surface facing the wall surfaces of the ribs of the plurality of blocks arranged at intervals in the tire circumferential direction,
The plurality of lug grooves are formed between the wall surfaces of the blocks adjacent to each other in the tire circumferential direction,
The wall surface facing the wall surface of the rib of one block for each of a plurality of blocks arranged at intervals in the tire circumferential direction has a full length portion extending in the tire circumferential direction facing the wall surface of the rib. It is formed as a wall surface for a narrow main groove portion located at a position displaced to the rib side compared to the wall surface of the other block,
A narrow main groove portion having a width Rn having a size smaller than the width Rw at a plurality of positions spaced in the extending direction of the main groove includes the narrow main groove portion wall surface and the narrow main groove portion wall surface. Is formed between the rib wall surfaces facing each other,
Out of both side portions of the narrow main groove portion in the extending direction of the main groove, drainage that extends to the outer side in the tire width direction and communicates with the main groove on a side portion of the narrow main groove portion on the front contact end side. A lateral groove is provided,
The drainage lateral groove is one of the plurality of lug grooves, and is formed as a wide lug groove having a width Lw larger than the width Ln of the other lug grooves,
An inner portion in the tire width direction of a wall surface forming the wide lug groove of the block in which the wall surface for the narrow main groove portion is formed forms an acute angle with the wall surface for the narrow main groove portion and the rotation direction of the tire to form the main Protrudes into the groove,
The narrow main groove portion extends over the entire length portion extending in the tire circumferential direction of the wall surface for the narrow main groove portion of the block with the width Rn.
A pneumatic tire characterized by that. The width of the main groove in the narrow main groove portion is Rn, the width of the main groove excluding the narrow main groove portion is Rw, the width of the wide lug groove is Lw, and the remaining width excluding the wide lug groove When the width of the lug groove is Ln, the relational expression of Rw × Ln = k · (Rn × Lw) is satisfied, where k is a coefficient of 0.9 ≦ k ≦ 1.1.
The pneumatic tire according to claim 1. When the width of the main groove in the narrow main groove portion is Rn, the width of the main groove excluding the narrow main groove portion is Rw, and the ratio of Rw / Rn is A, 2.0 ≦ A ≦ 5. Satisfies the relational expression of 0,
The pneumatic tire according to claim 1 or 2, characterized in that. When the width of the wide lug groove is Lw, the width of the remaining lug groove excluding the wide lug groove is Ln, and the ratio of Lw / Ln is B, a relational expression of 2.0 ≦ B ≦ 5.0 Meet,
The pneumatic tire according to any one of claims 1 to 3, characterized in that: The main grooves are provided on both sides of the tire equator,
The narrow main groove portions respectively provided in the main grooves on both sides are provided at locations that are out of phase with each other in the tire circumferential direction.
The pneumatic tire according to any one of claims 1 to 4, characterized in that:

Images