JPH06191226A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To provide a tread pattern enabling compatibility between excellent wet performance and a low noise characteristic. CONSTITUTION:In a pneumatic tire, a land part is partitioned by peripheral grooves 1a, 1b forming a pair on both sides of the equator of the tire, extended along the equator of the tire so as to divide each tread half part on the single side of the equator into a center area and a side area, and numerous inclined grooves 2a, 2b, 3a, 3b forming pairs with the equator of the tire in between, enlarged in mutual spacing from the equator side to both tread end sides and extended being inclined in relation to the equator. These inclined grooves are single-side opened to the peripheral grooves. The inclined grooves 2a, 2b in the center areas are extended from the vicinity of the equator with the inclination of 10-30 deg. to the equator and bent at the intermediate parts so as to be extended with the inclination of 50-80 deg. to the equator. The inclined grooves 3a, 3b in the side areas are extended form the peripheral grooves 1a, 1b with the inclination of 50-80 deg. to the equator and bent at the intermediate parts so as to be extended with the inclination of 10-30 deg. to the equator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire having a tread pattern which has low noise and excellent wet performance.

[0002]

2. Description of the Related Art In order to improve the wet performance of tires, particularly hydroplaning resistance, and to reduce noise, as shown in FIG. 1, a tread has a wide circumferential groove extending along its circumference. It is advantageous to arrange 10 and an inclined groove 20 which extends at a strong inclination with respect to the equator of the tire and intersects the circumferential groove 10. In particular, the ratio of the groove to the tread contact surface,
That is, when the negative ratio is increased, the wet performance is improved, but the noise characteristic is deteriorated. Conversely, when the negative ratio is decreased, the noise characteristic is improved but the wet performance is deteriorated.

[0003]

That is, in order to improve both the wet performance and the noise characteristic, it is not enough to simply adjust the negative ratio, and it is necessary to optimize the groove configuration and the inclination angle. is there. In particular, in the conventional tread pattern, the rigidity of the block end is likely to be insufficient, so this low rigidity part causes vibration,
It was causing tire noise.

Therefore, an object of the present invention is to propose a tread pattern which can achieve both excellent wet performance and low noise characteristics.

[0005]

DISCLOSURE OF THE INVENTION The inventors have studied a tread pattern that can satisfy the above-mentioned object, and have found that the arrangement of inclined grooves extending in the direction intersecting with the circumferential groove, particularly the optimization of the inclination angle of the tire with respect to the equator. Has been found to be advantageous, and the present invention has been completed.

That is, according to the present invention, a pair of tires are formed on both sides of the equator of the tire, and a tread half on one side of the equator is divided into a central region and a side region, and a circumferential groove extending along the equator of the tire, and the central region. In the side area and the side area, a pair of tires are formed with the equator interposed therebetween, and the land portion is formed by a large number of inclined grooves that extend from the equator side to both tread end sides and extend in a direction inclined with respect to the equator. A partitioned pneumatic tire, wherein the inclined groove is a one-sided opening toward the circumferential groove, the inclined groove in the central region extends from near the equator of the tire with an inclination of 10 to 30 ° with respect to this equator, It bends at its middle portion and extends at an inclination of 50 to 80 ° with respect to the equator and opens in the circumferential groove, while the inclined groove in the above-mentioned side region has an inclination of 50 to 80 ° from the circumferential groove to the equator of the tire. 10-30 ° to the equator Wherein the stop in the tread surface extends at an inclination, a pneumatic tire.

Now, FIG. 2 shows a main part of a tread of a pneumatic tire according to the present invention. The tread is arranged on both sides of the equator (circumference in the width center of the tread) O of the tire from the tread end T to the equator O side. In the illustrated example, one side of the equator O is divided into a central region C and a side region S by the circumferential grooves 1a and 1b which are paired at positions close to 1/4 of the tread width. Further, a large number of pairs are formed in the central region C and the side regions S with the equator O sandwiched therebetween, and the mutual distance is expanded from the equator O side to both tread ends T side and extends in a direction inclined with respect to the equator O. Inclined groove 2a, 2b
Place 3a and 3b. These inclined grooves 2a, 2b and
3a and 3b both open with the circumferential grooves 1a and 1b, and the other end with respect to the open end is near the equator O or the tread end T.
It is a groove with one side opening that stops in the vicinity, and therefore the tread tread has circumferential grooves 1a and 1b and inclined grooves 2a, 2b and
Due to the arrangement of 3a and 3b, block-shaped ribs 5a and 5b are similarly defined in the block-shaped ribs 4 continuous in the central area C on both sides of the equator O and the respective side areas S.

Furthermore, the inclination angles of the inclined grooves 2a, 2b and 3a, 3b with respect to the equator O of the tire change, that is, the groove portion C ₁ near the equator O of the inclined grooves 2a, 2b.
And the groove portion S ₂ of the inclined grooves 3a, 3b near the tread end is
The inclination angle α with respect to the equator O extends at 10 to 30 °, and the groove portions C ₂ and the inclination grooves of the inclination grooves 2a and 2b which are continuous to this extend respectively.
The groove portion S ₁ of 3a, 3b has an inclination angle β with respect to the equator O of 50-
In the illustrated example, the pattern extends symmetrically with respect to the equator O and extends at an inclination of 80 °.

Another tread pattern according to the present invention is shown in FIG. The tread pattern shown in FIG. 3 is shown in FIG.
In the tread pattern shown in Fig. 2, a central circumferential groove 1c is further arranged on the equator O of the tire, and a phase difference is provided between the inclined grooves 2a and 3a or 2b and 3b respectively arranged in the central area C and the lateral area S. Further, a large number of sipes 6a, 6b and 7a, 7b are arranged in the central area C and the side area S to further reduce noise.

Another structure of the tire according to the present invention is
Conventional tires may be used. For example, a carcass is at least one (up to three) turn-up ply that is wound around the bead core from the inside of the tire to the outside, and the ply is a fiber cord typified by rayon, nylon and polyester. The belt layer is arranged in a direction substantially perpendicular to the equatorial plane (radial direction), and the belt layer is made of non-stretchable cords such as steel cords and aromatic polyamide fiber cords at 10 to 35 ° with respect to the equatorial plane of the tire. Over the entire width of the main belt layer, where at least two layers of the belt arranged at an angle of
At least one auxiliary belt layer, in which heat-shrinkable cords represented by nylon cords are arranged substantially parallel to the equatorial plane of the tire, is formed by forming a plurality of cords along the circumference of the main belt layer. Each of the spirally wound ribbons is used. And on this belt layer,
Arrange the treads that form the tread pattern described above.

[0011]

In the present invention, on the tread tread, from each tread end, preferably 1/4 of the tread contact width
Sufficient drainage is first secured by the pair of circumferential grooves arranged at the positions separated from each other.

On the tread surface, the inclination angle of the inclined groove extending in the direction intersecting with the circumferential groove with respect to the equator of the tire is restricted to different inclination angles within the central region or side regions of the tread with the bending portion as a boundary. , Then depending on the reason.

That is, as shown in FIG. 2, the same is true for the groove portion C ₁ of the inclined groove in the central region C of the tread near the equator of the tire and the groove portion S ₂ of the inclined groove in the side region S near the tread end. The inclination angle α: The arrangement of 10 to 30 °, more preferably 15 to 25 ° is provided so that the inclination of less than 10 ° and more than 30 ° makes the water flow smooth in the central region C and the lateral region S of the tread. This is because it is not possible to lead to

The same inclination angle β: 50 to 80 °, more preferably 60, in the groove portion C ₂ of the inclined groove in the central region C of the tread and the groove portion S ₁ of the inclined groove in the side region S near the tread end. First, when the angle is less than 50 °, the rigidity at the corner P of the land defined by the inclined groove portion C ₂ or S ₁ and the circumferential groove is lowered to give the arrangement of ˜75 °. When is separated from the contact area, vibration with the corner P as a core is generated and causes pattern noise.
This is because the wear on the surface is given priority and causes uneven wear. By the way, uneven wear, such as heel and toe wear,
Although not fully clarified theoretically, it is considered to be one of the causes of pattern noise.

On the other hand, if the inclination angle β exceeds 80 °, the angle with respect to the circumferential groove becomes too large, and especially in the side area S, the water flow from the circumferential groove can be smoothly carried to the outside of the tread end. The drainage is hindered. In addition, the ground contact shape of the tread is usually closer to an ellipse than a rectangle, and the inclination of the contour line of the ground contact end shape is synchronized with the inclination of the groove portions C ₂ and S ₁ opening to the circumferential groove. Then, when the contact area separates from the road surface, the air in the groove is expelled at once, and pattern noise due to so-called pumping occurs, so the inclination angle β is set to less than 80 °.

Further, in the present invention, it is important that the end of the inclined groove in the side region S in the tread width direction is stopped within the tread tread without being opened at the tread end. This structure is necessary in relation to pattern noise because the ground contact pressure of the tire is generally larger in the side area than in the central area.

That is, the pattern noise, particularly the pumping noise, is partly due to the air discharged from the groove opening portion of the tread end. Since the end of the inclined groove is not opened to the tread end, this air is not discharged and the pumping noise does not occur. Is suppressed. In addition, the noise caused by the collision of the tire with the tread, so-called hitting noise, is also one of the causes of the pattern noise.The greater the change in the rigidity of the tread tread, the more discontinuous the shock propagation and the more pronounced the noise. By stopping the groove edge within the tread tread, the rigidity of the tread land portion is prevented from decreasing, and thus the shock propagation is continuous and the noise is suppressed. Furthermore, the noise caused by slippage between the tread and the tire is also a cause of the pattern noise, but since the end of the inclined groove does not open to the tread end, the block end is not formed on the tread side part, so the above slip is surely suppressed. , This is also effective as a pattern noise countermeasure. Here, the distance t between the tread width direction end of the inclined groove of the side region S and the tread end is preferably about 15 to 5 mm in view of expecting the above operation.

In the tire of the present invention, the same inclined groove in the load rolling direction is such that the contact area moves sequentially from near the equator of the tire to the tread end direction.
It is mounted on a vehicle and used.

[0019]

EXAMPLE A pneumatic radial tire with a tire size of 205/65 R15 (tread width: 160 mm) was used according to the tread pattern shown in FIG. 2, and the circumferential grooves 1a and 1b had a width of 6 mm and a depth of 8.5 mm. The inclined grooves 2a, 2b and 3a, 3b have a width of 5 mm on average and a depth of 7 mm on average, and the length of each groove portion is C ₁ :
35 mm, C ₂ : 12 mm, S ₁ : 15 mm and S ₂ : 35 mm, extending at an inclination angle α: 15 ° and an inclination angle β: 65 °, and the tread widthwise end and tread end of the inclined groove in the side area S. The prototype was made under the condition that the distance t was 10 mm.

For comparison, the tread pattern shown in FIG. 1 also has tires of the same size. The circumferential groove 10 has a width of 6 mm and a depth of 8.5 mm, and the inclined groove 20 has a width of 5 mm.
mm and depth: 7 mm, and prototyped under an arrangement extending at an inclination angle of 65 °.

Each of these prototype tires was mounted on a specified rim, and then the internal pressure was set to 1.9 kgf / cm ² and then mounted on an ordinary passenger car, and with two passengers riding, accelerating on a waterway with a water depth of 5 mm. The speed at which the tire started to float after the hydroplaning phenomenon occurred was measured. Also, after installing the tires on the actual vehicle under the same conditions, a feeling evaluation regarding noise when running at 40 to 100 km / h and 50, 80 km / h
A noise measurement with an instrument at h was performed.

The results of each of the above tests are shown in Table 1. In the table, the larger the index of drainage performance and the smaller the index of pattern noise, the better the results. As shown in the table,
The tire according to the present invention provided good results in both drainage performance and pattern noise.

[0023]

[Table 1]

[0024]

According to the present invention, a tread pattern having both excellent wet performance and low noise characteristics, which has been difficult to achieve by only improving the tread pattern in the past, can be provided, and the tread pattern can be improved. With this, high performance of the tire can be realized.

[Brief description of drawings]

FIG. 1 is a development view of a conventional tread pattern.

FIG. 2 is a development view of another tread pattern according to the present invention.

FIG. 3 is a development view of another tread pattern according to the present invention.

[Explanation of symbols]

 1a Circumferential groove 1b Circumferential groove 1c Circumferential groove 2a Inclined groove 2b Inclined groove 3a Inclined groove 3b Inclined groove 4 Rib 5a Rib 5b Rib 6a Sipe 6b Sipe 7a Sipe 7b Sipe

Claims (1)

[Claims] 1. A circumferential groove that is paired on both sides of the equator of a tire and divides a tread half on one side of the equator into a central region and a lateral region and extends along the equator of the tire, and the central region and the lateral region. In, a pair is formed with the equator of the tire sandwiched therebetween, and the land portion is divided by a large number of inclined grooves that extend from the equator side to both tread end sides and extend in a direction inclined with respect to the equator, In a pneumatic tire, the inclined groove is one side opening toward the circumferential groove, and the inclined groove in the central region extends from near the equator of the tire with an inclination of 10 to 30 ° with respect to the equator, and an intermediate portion thereof. Bend at and against the equator
The groove extends at an angle of 50 to 80 ° and opens in the circumferential groove, while the inclined groove in the side region extends at an angle of 50 to 80 ° from the circumferential groove to the equator of the tire, and bends in the middle portion thereof to bend at the equator. Against
A pneumatic tire characterized by extending at an inclination of 10 to 30 ° and stopping within the tread tread.