JP5064869B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire whose pattern changes as wear progresses.

In a typical directional pattern of a conventional pneumatic tire, the inclined groove is substantially V-shaped (for example, Patent Document 1) or W-shaped (for example, Patent Document 2) with respect to the rotation direction. In general, the form does not change from new to worn.
JP 2005-145307 A JP-A-8-324210

  In a pneumatic tire with a minimal groove arrangement, a substantially V-shaped pattern with respect to the rotational direction can achieve excellent drainage performance, but it can be braked when compared with a substantially W-shaped pattern. There is a problem that it is difficult to ensure the performance, and in the case of one substantially W-shaped pattern, it is difficult to ensure the drainage performance especially after wear even though the braking performance can be ensured. was there.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a pneumatic tire that can achieve both a braking performance when new and a drainage performance when worn.

The invention according to claim 1 is a pneumatic tire having a plurality of inclined grooves in the tread portion, wherein the shoulder side of the tread portion is a tread side region, and the tread side region and the tire equatorial plane are between. When the tread central region is used, the side region inclined groove provided in one of the tread side regions and the side region inclined groove provided in the other tread side region are inclined in opposite directions, and the tread central region In the side region inclined groove of the adjacent tread side region, the inclined direction is the reverse direction, the central region first inclined groove that is wide when new and wide when worn, and the first inclined groove of the tread side region The side region inclined groove has the same inclination direction, and is formed with a central region second inclined groove that is narrow when new and wide when worn .

Next, the operation of the pneumatic tire according to claim 1 will be described.
In the pneumatic tire according to claim 1, when the tire is new, the side inclined groove of one tread side region and the inclined groove of the other tread side region are opposite to each other and are provided in the tread central region. When the new product is wide, the first central inclined groove having a wide width is opposite to the side inclined groove in the adjacent tread side region, so that the tread pattern can be formed in a substantially W shape and has high braking performance. Can be obtained.
The reason why high braking performance can be obtained is as follows.
As shown in FIG. 8, the ground contact shape 100 of the pneumatic tire normally has the longest contact length in the circumferential direction of the tire equatorial plane CL, and the contact length in the circumferential direction becomes shorter toward the tread end.
Here, as shown in FIG. 8A, considering the case where the tread pattern is V-shaped, the V-shaped land portion 102 composed of a plurality of blocks is rotated from the circumferential end of the ground contact shape 100 when the tire rotates. When leaving (= away from the road surface), all the blocks constituting the V-shaped land portion 102 are separated from the road surface at substantially the same time.
On the other hand, as shown in FIG. 8B, considering the case where the tread pattern is W-shaped, when the tire rotates and the W-shaped land portion 104 moves away from the circumferential end of the ground contact shape 100, The block (near the tire equator CL) is in contact with the road surface to the end and all the blocks that make up the W-shaped land portion 104 do not leave the road surface at the same time. Thus, high braking performance can be ensured when new.

At the time of wear, one inclined direction from the side area inclined groove and the other side region inclined grooves in the tread side region of the tread side zone are opposite to each other, the central region second inclined groove width provided in the tread central region Since the inclination direction becomes the same direction as the side inclined groove of the adjacent tread side area, the tread pattern can be made substantially V-shaped, and drainage performance is better than the case of the substantially W-shaped. Can be improved.
Therefore, the pneumatic tire according to claim 1 can achieve both the braking performance when new and the drainage performance when worn.

According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, the central region second inclined groove is provided inside the tread portion and exposed to the tread when worn, and the side region inclined groove A first cavity to be connected and a first sipe that connects the first tread surface and the first cavity are formed.

Next, the operation of the pneumatic tire according to claim 2 will be described.
In the pneumatic tire according to claim 2, in the tread central region, a wide central region first inclined groove is exposed on the tread surface when new, and the central region first inclined groove drains water when traveling on a wet road surface. Do.
When the groove width of the first inclined groove in the central area becomes narrower due to wear of the tread portion, the first cavity (cavity) of the second inclined groove in the central area is exposed to the tread surface and inclined in the same direction as the inclined groove in the side area. Since the new inclined groove is connected to the side region inclined groove, drainage can be performed continuously and efficiently from the tire equatorial plane side to the tread end outer side.

If the first cavity is formed independently in the block, the rubber will be torn when the tire is removed from the mold. To prevent the rubber from being torn, a machine such as moving a part of the mold is used. Mechanism is separately required for the mold, and the structure of the mold becomes complicated.
On the other hand, when the first cavity and the tread surface are connected by the first sipe, the first cavity is formed at the end of the blade (thin metal plate) for forming the first sipe. It is only necessary to integrally form a wide portion for the purpose, the wide portion can be easily pulled out through the first sipe without tearing the rubber after vulcanization, and the mold structure is not complicated.

The invention according to claim 3, in the pneumatic tire according to claim 1 or claim 2, in the tread portion, circumferentially extending exposed to the tread surface at the time of wear is provided inside of the tread portion periphery A circumferential tunnel-shaped sipe having a second cavity that forms a directional groove and a second sipe that connects the second tread surface to the second cavity is formed.

Next, the operation of the pneumatic tire according to claim 3 will be described.
At the time of new, the tread of the tread portion is exposed a second sipe in the circumferential direction tunnel-like sipes, the frictional force between the road surface is enhanced.

As the tread portion wears , the second cavity of the circumferential tunnel-shaped sipe is exposed to the tread surface and forms a circumferential groove extending in the circumferential direction, so that the drainage at the time of wear can be improved.

  As described above, according to the pneumatic tire of the present invention, there is an excellent effect that both the braking performance when new and the drainage performance when worn can be achieved.

  A pneumatic tire 10 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG. 1A shows a plan view of a tread 12 when the pneumatic tire 10 of the present embodiment is new. In FIG. 1, the direction of arrow A is the rotational direction.

  With the tread end 12E side of the tread 12 as the boundary between the tread end 12E of the tread 12 and the tire equatorial plane CL (so-called 1/4 point) as a boundary, the tread side area 12S and the tire equatorial plane CL A tread side region 12S is formed with a side region inclined groove 14 that is inclined with respect to the tire circumferential direction. The side region inclined groove 14 is inclined so that the tire equatorial plane side contacts the ground first. Therefore, the inclination direction of the one side side inclined groove 14 and the other side side inclined groove 14 is opposite to each other across the tire equatorial plane CL. The side region inclined groove 14 of the present embodiment is formed in a substantially U-shaped cross section as shown in FIG. 2 so that the change in groove width is small from the new article to the end of wear.

  The tread end 12E in this embodiment is the end in the width direction of the tire contact surface when a tire is mounted on an applicable rim, set to a specified air pressure, placed perpendicular to a flat plate in a stationary state, and a specified mass is added. The tire is mounted on a standard rim in accordance with JATMA YEAR BOOK in 2007 in the JATMA standard, and the maximum load capacity and the corresponding air pressure (maximum air pressure) in the applicable size / ply rating are used as a reference. When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards are followed.

  As shown in FIG. 1, circumferential tread-shaped sipes 16 extending along the circumferential direction are formed on both sides of the tire equatorial plane CL at the tread center 12C, and the side region inclined grooves of the adjacent tread side region 12S are formed. An inclined tunnel-shaped sipe 20 that is inclined in the same direction is formed between the central region first inclined groove 18 inclined in the direction opposite to the direction 14 and the side region inclined groove 14 of the adjacent tread side region 12S. Note that the inclined tunnel-shaped sipe 20 is disposed on an extension line of the side region inclined groove 14 on the tire equatorial plane CL side.

  Here, the end portions of the side region inclined groove 14 and the central region first inclined groove 18 which are adjacent to each other are in contact with each other, and the central region first inclined groove 18 on one side and the other side across the tire equatorial plane CL. The end portions of the central region first inclined groove 18 are close to each other. When new, the side region inclined grooves 14 and the central region first inclined groove 18 are arranged in a substantially W shape as shown in FIG.

  As shown in FIG. 3, the circumferential tunnel sipe 16 has a narrow groove width on the tread surface side (hereinafter referred to as a narrow portion 16A) and a wide groove width on the bottom side (hereinafter referred to as a wide portion 16B). ), The narrow portion 16A is a so-called sipe (groove width that closes at the time of ground contact), and the wide portion 16B is a groove that can secure drainage in the circumferential direction after the tread 12 is worn and opened on the tread surface. The circumferential groove 22 having a width is formed. The wide portion 16B corresponds to the second cavity of the present invention. The circumferential tunnel-shaped sipe 16 is connected to the end portion of the inclined tunnel-shaped sipe 20 on the tire equatorial plane CL side.

As shown in FIG. 4, the central region first inclined groove 18 of the present embodiment is formed in a substantially V-shaped cross section so that the groove width becomes narrow at the end of wear.
As shown in FIG. 5, the inclined tunnel-shaped sipe 20 is also provided with a narrow portion 20A and a wide portion 20B, similar to the circumferential tunnel-shaped sipe 16, and the wide portion 20B is opened after the tread 12 is worn and opened to the tread surface. The central region second inclined groove 24 having a groove width substantially equal to the side region inclined groove 14 is formed. The wide portion 20B corresponds to the first cavity of the present invention.

(Function)
Next, the effect | action of the pneumatic tire 10 of this embodiment is demonstrated.
The pneumatic tire 10 of the present embodiment has a substantially W-shaped tread pattern having a directivity as shown in FIG. 1 when it is new, and the ground contact state is good compared to the V-shaped tread pattern, so that high braking is achieved when new. Performance can be ensured.
Further, when new, the narrow portion 16A (sipe portion) of the circumferential tunnel-shaped sipe 16 is exposed on the tread surface of the tread 12, and the frictional force with the road surface is enhanced.

  When this pneumatic tire 10 is used for traveling and wear of the tread 12 progresses to some extent, as shown in FIG. 1 (B), the central region first inclined groove 18 almost disappears and the central region second inclined groove 24 appears. By connecting with the side region inclined groove 14, a substantially V-shaped pattern is formed, and the circumferential groove 22 also appears and is connected to the central region second inclined groove 24. In addition to being discharged in the circumferential direction via 22 and drained to the outside of the tread end via the central region second inclined groove 24 and the side region inclined groove 14, high drainage performance can be obtained even during wear.

  In the inclined tunnel-shaped sipe 20, the wide portion 20B and the tread surface are connected by the narrow portion 20A. For this reason, in the vulcanization mold, the wide portion for forming the wide portion 20B (first cavity) is integrated with the end portion of the blade for forming the narrow portion 20A (first sipe). The wide portion can be easily pulled out through the narrow portion 20A without tearing the rubber after vulcanization, and the structure of the mold is not complicated. The same applies to the circumferential tunnel-shaped sipe 16.

[Other Embodiments]
In the said embodiment, although the cross-sectional shape of the center area 1st inclination groove | channel 18 was substantially V shape, other cross-sectional shapes, such as U shape, may be sufficient. The same applies to the cross-sectional shapes of other inclined grooves.

(Test example)
In order to confirm the effect of the present invention, one type of pneumatic tire according to an embodiment to which the present invention was applied and two types of pneumatic tires according to the conventional example were produced, and each test tire was run at a new time and 10000 km. Later, dry road braking performance evaluation and hydroplaning performance evaluation were performed.
In the test, the test tire is a summer tire with a tire size of 205 / 55R16, a rim width of 6.5J-16, mounted on a domestic car sedan, and under a load condition in which 600 N is added to the weight of the driver. Performed by filling specified internal pressure.

  Pneumatic tire of Example: The tire according to the embodiment described above, and the tread pattern changes from a substantially W shape to a substantially V shape.

  Pneumatic tire of conventional example 1 (substantially V-shaped pattern): A pneumatic tire 100 of a conventional example will be described based on FIG. As shown in FIG. 6 (A), in the new tread 102, circumferential grooves 104 are formed on both sides of the tire equatorial plane CL, and inclined grooves 106 are formed outside the circumferential grooves 104 in the tire width direction. In addition, a sipe 108 that is inclined in a direction opposite to the inclined groove 106 is formed. The inclined groove 106 on one side of the tire equatorial plane CL is inclined in the opposite direction to the inclined groove 106 on the other side. As shown in FIG. 6B, the tread 102 after wear of the pneumatic tire 100 has the same pattern (see FIG. 6A) as when it was new.

Pneumatic tire of conventional example 2 (substantially W-shaped pattern): A conventional pneumatic tire 200 will be described with reference to FIG.
As shown in FIG. 7A, in the tread 202, first inclined grooves 204 are formed on both sides of the tire equatorial plane CL, and the first inclined grooves 204 are adjacent to the outer sides of the first inclined grooves 204 in the tire width direction. A second inclined groove 206 that is inclined in the opposite direction to the inclined groove 204 is formed. The first inclined groove 204 on one side of the tire equatorial plane CL is inclined in the opposite direction to the first inclined groove 204 on the other side. In the tread 202, a sipe 208 is formed on the extended line of the second inclined groove 206, and sipe 210 extending in the circumferential direction is formed on both sides of the tire equatorial plane CL. As shown in FIG. 7 (B), the tread 202 after wear of the pneumatic tire 200 has the same pattern (see FIG. 7 (A)) as when it is new.

  Braking performance: On a dry road, the deceleration from 100 km / h was measured in a state where the ABS function was exhibited. The evaluation was expressed as an index with the deceleration of the conventional example as 100. In addition, the one where a numerical value is large represents that it is excellent in braking performance.

  Hydroplaning performance: Hydroplaning generation speed during acceleration was measured on a road surface having a water depth of 10 mm. The evaluation is represented by an index with the hydroplaning occurrence speed of the conventional example as 100, and a larger numerical value indicates that the hydroplaning occurrence speed is higher and the performance is excellent.

試験結果から、本発明の適用された実施例の空気入りタイヤは、制動性能、及びハイドロプレーニング性能を両立できていることが分かる。

From the test results, it can be seen that the pneumatic tire of the example to which the present invention is applied can achieve both braking performance and hydroplaning performance.

(A) is a top view of the tread which shows the pattern at the time of the new article of the pneumatic tire concerning the embodiment of the present invention, and (B) is a top view of the tread which shows the pattern at the time of wear. It is sectional drawing of a side area inclination groove | channel. It is sectional drawing of the circumferential direction tunnel-shaped sipe. It is sectional drawing of a center area 1st inclination groove | channel. It is sectional drawing of an inclined tunnel-like sipe groove. (A) is a top view of the tread which shows the pattern at the time of the new article of the pneumatic tire which concerns on the prior art example 1, (B) is a top view of the tread which shows the pattern at the time of wear. (A) is a top view of the tread which shows the pattern at the time of the new article of the pneumatic tire which concerns on the prior art example 2, (B) is a top view of the tread which shows the pattern at the time of wear. (A) is explanatory drawing which shows the relationship between a V-shaped tread pattern and a grounding shape, (B) is explanatory drawing which shows the relationship between a W-shaped tread pattern and a grounding shape.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Pneumatic tire 12 Tread 12S Tread side area 12E Red end 12C Tread center area 14 Side area inclined groove 16 Circumferential tunnel-shaped sipe 16A Narrow part (2nd sipe)
16B Wide part (second cavity)
18 Inclined groove (Center area inclined groove)
20 Inclined tunnel-shaped sipe 20A Narrow part (first sipe)
20B Wide part (first cavity)
22 circumferential groove 24 inclined groove

Claims (3)

A pneumatic tire having a plurality of inclined grooves in the tread portion,
When the shoulder side of the tread portion is the tread side region, and the tread side region and the tire equatorial plane are the tread central region,
The inclination direction of the side region inclined groove provided in one of the tread side regions and the side region inclined groove provided in the other tread side region are opposite to each other,
The tread central region has a first central inclined groove that is opposite in inclination direction to the side region inclined groove of the adjacent tread side region, and is wide when new and narrow when worn, and the tread. Pneumatically characterized in that the side area inclined groove is in the same direction as the side area inclined groove, and is formed with a central area second inclined groove that is narrow when new and wide when worn. tire. The central region second inclined groove is provided inside the tread portion and is exposed to the tread surface when worn and connected to the side region inclined groove, and the new tread surface and the first cavity. The pneumatic tire according to claim 1, wherein a first sipe that connects the two is formed. Said tread portion includes a second cavity forming an internal circumferential groove extending in the circumferential direction is exposed to the tread surface during wear provided of the tread portion, said a tread surface at the time of a new second cavity The pneumatic tire according to claim 1, wherein a circumferential tunnel-shaped sipe including a second sipe that connects the two is formed.

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