JPH04271905A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve the operation stability on a dry road surface, and while improve the wetting performance, and reduce the pattern noise by devising shape of a cross directional channel to be extended to the cross direction of a tread, and raising a degree of freedom of angular change of a central part of the tread. CONSTITUTION:A pair of circumferential main channels 3 are formed in a central part 2 of a tread surface 1, and while multiple cross directional main channels 4 are formed over the whole of the tread width with a space in the tire circumferential direction. Block lines 7, 8 are thereby formed in a central block 5 and each side block 6 positioned in the end sides from the circumferential main channels 3. In this case, an extension part of each cross directional main channel 4 in the side blocks 6 are inclined to the same direction against a tire circumferential line segment, and a crossing angle theta, against the tire circumferential line segment is set at 60-80 deg.. Extending direction of each cross directional main channel 4 near the tread center among the extension parts thereof in the central block 5 is directed reversely to the described direction, and a crossing angle theta2 thereof is set at 5-25 deg..

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION This invention relates to a general high-performance pneumatic tire with an aspect ratio of about 60%, and in particular, it is intended to achieve both improved wet performance and reduced pattern noise at a high level.

0002

[Prior Art] Conventionally, this type of tire has improved handling stability on dry roads, improved wet performance including hydroplaning resistance, braking performance, handling stability, etc. on wet roads. In particular, tread patterns are designed to achieve a good balance between reducing pattern noise and improving cabin comfort, and in many cases, tread patterns are designed to have a circumferential main groove that extends linearly in the circumferential direction of the tire, and a width A tread pattern that combines directional grooves is adopted.

[0003] In addition to the widthwise groove extending in a substantially S-shape or inverted S-shape from one tread edge to the other tread edge, there are also widthwise grooves extending at each boundary position between the tread center area and each side edge area. Generally, grooves that are bent and extended into an almost N-shape are widely used.
By reducing the intersection angle with the circumferential line of the tire, and gradually increasing the intersection angle of the widthwise groove toward the tread edge, the company aims to both improve wet performance and reduce pattern noise. .

0004

[Problems to be Solved by the Invention] By the way, in such conventional tires, the tread pattern of the tire is
In other words, it is composed of a simple combination of a linear circumferential main groove and a general width direction groove.
For each width direction groove, the intersection angle with the tire circumferential line segment of the portion extending in the tread center area is made small, while the same intersection angle of the width direction groove is gradually increased toward the tread edge. Since this is just a contrivance, the pitch length is limited after securing the number of pitches to obtain a sufficient pitch variation effect, so setting the intersection angle small will reduce the rigidity of the block surrounded by the groove. The degree of freedom in changing the inclination angle of the width direction grooves, especially in the central part of the tire, is low, such as the inability to secure the groove angle, which is particularly effective in reducing pattern noise. It was not possible to clearly distinguish between the parts having functional groove angles, and as a result, it was not possible to achieve both improvement in wet performance and reduction in pattern noise at a high level.

[0005] Therefore, with the main purpose of reducing pattern noise, it has been proposed to separate the portions of each width direction groove, for example, located across the tread center, by a predetermined distance in the tire circumferential direction. According to the above, there was a problem in that the wet performance deteriorated significantly because the drainage water did not flow continuously through each width direction groove.

The present invention advantageously solves the problem of the prior art by devising the shape of the widthwise groove and increasing the degree of freedom in changing the angle of the widthwise groove at the center of the tread. In particular, by specifying the extending direction of each part in the tread width direction of the width direction groove extending from one tread end to the other tread end, as well as the intersection angle of those parts with the tire circumferential line segment. The present invention provides a pneumatic tire that not only provides excellent handling stability on dry road surfaces, but also achieves both improved wet performance and reduced pattern noise at a sufficiently high level.

[0007]

[Means for Solving the Problems] The pneumatic tire of the present invention is provided with at least one pair of circumferential main grooves forming a pair in the center of the tread, and which extend from one tread end to the other tread end. A plurality of widthwise main grooves are provided at intervals in the tire circumferential direction, with a central area defined between a pair of circumferential main grooves, and each area located closer to the tread end than the circumferential main grooves. A tire in which a row of blocks is formed in a side area of the tire, wherein the extending portions of each widthwise main groove in each side area are both inclined in the same direction with respect to a line segment in the circumferential direction of the tire. and the intersection angle of each of these extending portions with respect to the tire circumferential line segment is in the range of 60 to 80°, and among the extending portions of each width direction main groove in the central area, the vicinity of the tread center The extending direction of the part is opposite to the extending direction of the width direction main groove in the side area, and the intersection angle with the tire circumferential line segment of the neighboring part is in the range of 5 to 25 degrees. It is.

[0008] Preferably, at least between the pair of circumferential main grooves, a portion extending from each of the circumferential main grooves in a direction opposite to a portion of the widthwise main groove near the tread center, Widthwise minor grooves are formed that end without intersecting the portion, and the intersection angle of each widthwise minor groove with the tire circumferential line segment is 20° or more larger than the similar intersection angle of the portion near the tread center.

[0009] Also, preferably, the groove width of the portion of the width direction main groove near the tread center is narrower than the groove width of other portions of the width direction main groove, and more preferably, the groove width of that portion is set to the maximum width. The range is 50 to 80% of the groove width.

More preferably, the ratio of the length of the widthwise main groove extending in the vicinity of the tread center to the total length of the widthwise main groove extending in the central area is 50 to 80%. The range shall be .

[0011]

[Function] In this pneumatic tire, the intersection angle of the extending portion of the width direction main groove in the tread side area with the tire circumferential line segment is in the range of 60 to 80°, so that the tread side area is To ensure high lateral rigidity of each block and also to enable smooth and quick drainage outward in the tread width direction. If the intersection angle is less than 60°, the lateral rigidity of the block will decrease, resulting in a decrease in steering stability on dry roads. In the so-called point-symmetric pattern shown in the figure, which differs greatly between turning in the direction and turning to the left, the main groove in the width direction extending in one side area matches the contact profile of the tire and reduces pattern noise. There is a high possibility that this will result in a significant increase. On the other hand, if the intersection angle exceeds 80°, there will be no particular problem with wet drainage performance or block rigidity, but the block rigidity of the widthwise main groove extending in the opposite direction in the central area of the tread will be affected. This increases the possibility that the straight-line performance of the vehicle will be impaired.

[0012] Furthermore, by making the extending direction of the widthwise main groove near the tread center opposite to the extending direction of the widthwise main groove in the tread side area, the vehicle can be driven straight. By ensuring sufficient running performance and by setting the intersection angle of the tread center area with respect to the tire circumferential line segment to be in the range of 5 to 25 degrees, wet drainage performance is effectively improved, and the groove edge portion and It smoothes the collision with the road surface and effectively reduces pattern noise. In other words, if it is less than 5 degrees, it will be difficult to ensure the lateral rigidity of the block divided by the general pitch interval in each width direction main groove, and the If the angle exceeds 25 degrees, the significant wet drainage effect will be diminished and pattern noise will tend to increase.

Further, in this pneumatic tire, between the pair of circumferential main grooves, a portion extending from each circumferential main groove in a direction opposite to a portion near the tread center of the widthwise main groove, When a widthwise minor groove is formed that ends without intersecting the tread center, the straightness of the vehicle can be improved by extending the widthwise minor groove in a direction opposite to the portion near the tread center. ,and,
By not intersecting the width direction minor groove with the portion near the tread center, the discontinuous portion between the two can ensure smooth grounding of the block and advantageously prevent an increase in pattern noise.

[0014] Here, if the intersection angle of the width direction minor groove with the tire circumferential line segment is made larger by 20° or more than the intersection angle of the width direction main groove with the tire circumferential line segment in the vicinity of the tread center, the tread Sufficient rigidity of the side end portions of the blocks in the central area can be ensured to provide excellent handling stability, and at the same time, edge components extending in the tread width direction can be increased to improve wet braking performance.

[0015] Also, in order to keep the circumferential cross-sectional area of the width direction main groove constant, even if the groove width in the vicinity of the tread center is narrower than the groove width in other parts of the width direction main groove,
Drainage can be made extremely smooth and rapid, and this is particularly noticeable when the groove width in the vicinity of the tread center is set in a range of 50 to 80% of the maximum groove width.

Furthermore, the total length of the widthwise main groove near the tread center is 50 to 80% of the same length of the widthwise main groove extending in the tread center area.
By doing so, based on the action of the part of the width direction main groove near the tread center, wet drainage performance is further improved.
Moreover, pattern noise can be further reduced. If it is less than 50%, it will not be possible to sufficiently improve wet drainage and reduce pattern noise in the vicinity of the tread center, and if it exceeds 80%, the vicinity of the tread center will be affected in the circumferential direction. Being too close to the main groove makes it difficult to provide the required rigidity to the circumferentially adjacent end of the block in the tread center area adjacent to the main groove.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 1 shows a tread pattern showing one embodiment of the present invention. Note that the reinforcing structure of the tire is the same as that of a general radial tire, so illustration thereof is omitted here. This tire has a size of 205/60R15
, the width of the tread surface portion 1 is 164 mm, and a pair of circumferential main grooves 3, which form a pair and extend linearly in the circumferential direction of the tire, are arranged in the central portion 2 of the tread surface portion 1 as far as possible. By forming a plurality of width direction main grooves 4 extending substantially continuously from one tread end to the other tread end at intervals in the tire circumferential direction, a pair of circumferential grooves is formed. Block rows 7 and 8 are formed in the central area 5 divided between the directional main grooves, and in the side areas 6 located at the tread end from each circumferential main groove, and here, block rows 7 and 8 are formed in each width. The direction main groove 4 extends upward to the right in a portion 9 near the tread center XX, and extends downward to the right on the tread end side from the portion 9 near the tread center.

Further, here, each of the tread side regions 6 is formed with a circumferential narrow groove 10 extending linearly in the tire circumferential direction, and each of the widthwise main grooves 4 mentioned above is formed in each circumferential direction. By cutting the trace over a small distance from the direction narrow groove 10 at the center of the tread, it is possible to increase the rigidity of the block, improve steering stability on dry roads, and wet braking performance. By making the grooves 4 alternately discontinuous in the circumferential direction, pattern noise can be dispersed and reduced.

In addition, in this tire, a line segment in the tire circumferential direction of the extending portion 4b of the width direction groove in the tread side region 6,
Here, the intersection angle θ1 with respect to the circumferential narrow groove 10 is 60 to 8
0°, and the intersection angle θ2 of the tread center vicinity portion 4a of the width direction main groove 4 with respect to the tire circumferential direction line segment, here the tread center XX, is 5 to 2.
5° range, and furthermore, between the pair of circumferential main grooves, extending from each circumferential main groove 3 in the opposite direction to the tread center vicinity portion 4a of the width direction main groove 4, the tread center A width direction minor groove 11 that ends without intersecting the vicinity portion 4a is formed, and the intersection angle θ3 of the width direction minor groove 11 with respect to the tire circumferential direction line segment, here the circumferential direction main groove 3, is set to the tread center vicinity portion 4a. 20 from the intersection angle θ2
Increase by more than °. In addition, here, tread center
Each of the width direction minor grooves 11 located apart from each other by -X intersects each of the circumferential direction main grooves 3 and extends to the tread end without being cut.

Furthermore, the groove width d of the portion 4a near the tread center of the width direction main groove 4 is made narrower than the groove width of other portions of the width direction main groove 4, and more preferably, the groove width d is made narrower than the groove width of other portions of the width direction main groove 4. , is in the range of 50 to 80% of the maximum groove width of the width direction main groove 4, and preferably, the width direction main groove 4 is in the range of 50 to 80% of the maximum width of the width direction main groove 4. The similar length ratio of the portion 4a of the groove 4 near the tread center is in the range of 50 to 80%.

According to the tire constructed as described above,
The above-mentioned effects can be brought about, and excellent handling stability on dry road surfaces can be ensured, while improving wet performance and reducing pattern noise can be achieved extremely effectively.

FIG. 2 is a tread pattern showing another embodiment of the present invention, which has a tread pattern as compared to the previous embodiment.
The width of the tread center area 5 is made somewhat wider, and the tips of the widthwise minor grooves 11 located across the tread center vicinity portion 4a of the widthwise major grooves 4 intersect with the two widthwise major grooves 4. The extending sipes 12 smoothly communicate with each other, and the respective ends of the tread center vicinity portion 4a in the tire circumferential direction are connected to each other by the sipes 13 extending across one circumferential main groove 4. It is a communication.

FIG. 3 shows a tread pattern showing still another embodiment, which has a tread pattern in which the intervals between the circumferential main grooves 3 are narrowed compared to the embodiment shown in FIG. The main groove 4 is completely continuous from one tread end to the other tread end, and the tips of the circumferential sub-grooves 11 protruding from each circumferential main groove 3 toward the tread center are connected to one width-direction main groove. The grooves 4 are located apart from each other.

[0024] The tires of these examples also provide
By meeting the angle requirements and other requirements essential to the present invention, it is possible to effectively improve steering stability on dry roads and wet performance, and reduce pattern noise, similar to the tire shown in FIG. Can be done.

[Comparative Example] Comparative tests between the invention tire and the conventional tire regarding wet drainage performance, wet braking performance, and low pattern noise will be described below. ◎Test tire size 205/60R15 Tread width 164mm

- Invention Tire I A tire having a tread pattern shown in FIG.
The groove width of the circumferential main groove 3 is 11.0 mm, the groove width of the circumferential narrow groove 10 is 4.0 mm, the width of the tread center area 5 is 48 mm, the width of the side area 6 is 47 mm, and the width of the tread center area 5 is 48 mm. The groove width d of the portion 4a near the tread center of the main groove 4 is 3.5 to 4.0 mm, the intersection angle θ2 of that portion 4a with respect to the tread center XX is 10 to 15 degrees, and the width direction main groove with respect to the circumferential narrow groove 10 is The intersection angle θ1 of the groove 4 is set to 60~
80°, the groove width D of the width direction minor groove 11 in the tread side area 6 is 5.0 to 6.0 mm, and the width direction minor groove 1
1, the groove width E in the tread central area 5 is 4.5 mm.
, its intersection angle θ3 with respect to the circumferential main groove 3 is 45°.
Further, the total length of the width direction main groove 4 extending in the tread center area 5 is 112 mm, and the similar length of the width direction main groove 4 near the tread center portion 4a is 76 mm.
What was said.

- Invention Tire II A tire having a tread pattern shown in FIG.
The width of the tread central region 5 is 56 mm, the width of the tread side regions is 44 mm, the total length of the width direction main groove 4 extending in the tread center region 5 is 136 mm, and the portion of the width direction main groove 4 near the tread center. The similar length of 4a is 10
The groove width, groove angle, etc. are the same as those shown in Fig. 1, except that the groove width is 0 mm. Note that the sipes 12 and 13 in this example have a groove width of 0.7 mm.

- Invention Tire III A tire having a tread pattern shown in FIG.
The width of the tread center area 5 is 48 mm, the width of the tread side area 6 is 48 mm, the total length of the width direction main groove 4 extending in the tread center area 5 is 86 mm, and the width direction main groove 4 is 48 mm.
The same length of the tread center vicinity portion 4a is 50 m.
m.

- Conventional Tire A tire having the tread pattern shown in FIG. 4 and the various dimensions indicated therein.

◎Test method Tires filled with the internal pressure specified by JIS were installed on an actual vehicle, and under the load condition of two passengers, the wet drainage performance was tested to determine the occurrence of hydroplaning when driving on a wet road with a water depth of 5 mm. Speed is detected and evaluated. Wet braking performance is evaluated by measuring the coefficient of friction during braking on a wet road surface with a water depth of 0 mm. Pattern noise is evaluated by measuring the coefficient of friction during braking on a wet road surface with a water depth of 0 mm.
The interior noise during driving was evaluated based on feeling.

◎Test Results The results of each of the above tests are shown in Table 1 with index values. The index value is assumed to be 100 for each test result of conventional tires, and the larger the index value, the better the result.

[0032]

According to Table 1, it is clear that all of the invention tires can effectively improve wet drainage performance, wet braking performance, and low pattern noise over those of the conventional tires.

[0034]

Thus, according to the present invention, it is possible to simultaneously improve wet performance and reduce pattern noise at a high level while improving steering stability on dry road surfaces.

[Brief explanation of the drawing]

FIG. 1 is a tread pattern showing an embodiment of the invention.

FIG. 2 is a tread pattern showing another embodiment of the invention.

FIG. 3 is a tread pattern showing still another embodiment of the invention.

FIG. 4 is a tread pattern showing a conventional example.

[Explanation of symbols]

1 Tread surface 2 Central part 3 Circumferential main groove 4 Width direction main groove 4a Part near tread center 4b Extension part 5 Central area 6 Side area 7, 8 Block row 10 Circumferential thin groove 11 Width direction sub width 12, 13 Sipe

Claims (4)

[Claims] Claim 1: At least one pair of two circumferential main grooves is provided in the center of the tread, and a plurality of width main grooves extending from one tread end to the other tread end are provided in the tire circumferential direction. Block rows are formed at intervals at intervals in a central area defined between the pair of circumferential main grooves and in respective side areas located closer to the tread end than the circumferential main grooves. The tire is characterized in that the extending portions of the widthwise main grooves in the respective side areas are both inclined in the same direction with respect to the tire circumferential line segment, and the extending portions of the respective extending portions in the tire circumferential direction are The intersection angle with the direction line segment is 60
~80°, and the extending direction of the portion near the tread center of the extending portion of each widthwise main groove in the central region is set at the side region of the widthwise main groove. A pneumatic tire in which the direction is opposite to the extending direction of the pneumatic tire, and the angle of intersection with the tire circumferential line segment in the vicinity thereof is in the range of 5 to 25 degrees. Claim 2: At least between a pair of circumferential main grooves, extending from each of the circumferential main grooves in a direction opposite to the portion of the widthwise main groove near the tread center and intersecting the portion near the tread center. Claim 1: forming widthwise minor grooves that end without a tread, and having an intersection angle of each widthwise minor groove with respect to a line segment in the circumferential direction of the tire that is 20 degrees or more larger than a similar intersection angle in the vicinity of the tread center. Pneumatic tires listed. 3. The pneumatic tire according to claim 1, wherein the groove width of a portion of the width direction main groove near the tread center is narrower than the groove width of other portions of the width direction main groove. 4. The ratio of the length of the widthwise main groove extending in the vicinity of the tread center to the total length of the widthwise main groove extending in the central area is in the range of 50 to 80%. The pneumatic tire according to any one of claims 1 to 3.