JP2001191739A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To assure sufficient draining performance and greatly improve driving performance and braking performance on snow and ice. SOLUTION: A tread portion 2 is provided with a plurality of peripheral grooves 3, 4, 5 extending to the peripheral direction in a zigzag pattern and slope grooves 6 extending from tread ends toward a tread center in an almost stepwise form in mutual opposite directions. A directional tread pattern has a plurality of block trains 7, 8, 9 formed on the tread portion 2 with the peripheral grooves 3, 4, 5 and the slope grooves 6. Blocks 10, 11 of the block trains 7, 8 formed between the peripheral grooves have hexagonal contours and all corner of the blocks 10, 11 have obtuse angles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire for winter and, more particularly, to a tread pattern for achieving both high performance on ice and high performance on snow.

[0002]

2. Description of the Related Art As a tread pattern of a conventional pneumatic radial tire for a passenger car which can exhibit both performance on ice and performance on snow, there is a tread pattern illustrated in FIG. This is achieved by providing circumferential grooves 32 and 33 extending linearly at substantially the center position of the tread tread portion 31 and at positions near each side end, and circumferentially between the linear circumferential grooves. A zigzag bent circumferential groove 34 is provided on the tread portion 31. The tread 31 has a lateral groove 35 extending substantially linearly in the width direction from the tread ground end to the bent circumferential groove position. A communication groove 36 is provided at a portion of the direction groove 34 adjacent to the linear circumferential groove 32, and a communication groove 36 for communicating the two is provided, and each block defined by these respective grooves tends to extend in the width direction. Four zigzag sipes 37 are formed at substantially equal intervals.

In such a tread pattern, the edge of each block contributes to the performance on snow and on ice, and the edge of each sipe 37 improves the performance on ice, in particular, and the linear circumferential direction. Grooves 32, 33
Improves the drainage performance, so that the performance on ice and the performance on snow can be exhibited in a well-balanced manner.

[0004]

However, in such prior art, the linear circumferential grooves 32, 33 for improving drainage performance do not have an edge component extending in the width direction of the tread tread portion. This is disadvantageous for the driving and braking performance on snow and ice, which becomes more significant as the number of linear circumferential grooves increases.

Accordingly, the present invention provides a pneumatic tire capable of sufficiently improving both the driving performance and the braking performance on snow and ice, while ensuring sufficient drainage performance of the tread tread.

[0006]

According to the pneumatic tire of the present invention, a plurality of circumferential grooves extending circumferentially in a zigzag manner are provided in a tread tread portion, and each tread tread edge is directed toward the center of the tread surface. In the pneumatic tire having a directional tread pattern formed by forming a plurality of block rows on the tread tread portion by providing inclined grooves extending substantially stepwise in opposite directions to each other, by the circumferential grooves and the inclined grooves, The outline shape of each block of the block row partitioned between the circumferential grooves is a pentagon or more polygonal shape, and all corners of each block are obtuse.

In this tire, by forming two or more circumferential grooves, in addition to the drainage performance on a wet road surface, it is possible to ensure the skid resistance on snow, and the circumferential grooves are formed. In addition, by extending in a zigzag manner, in addition to driving and braking performance on snow and ice, turning performance can also be advantageously improved. And here,
By making the tread pattern directional, it is possible to achieve improvement in drainage performance and further improvement in driving performance on snow.

[0008] In addition, in this tire, the outline of each block of the block row defined between the circumferential grooves is formed into a polygonal shape of a pentagon or more, and edge components in various directions are given to each block, so that With the block, in addition to the driving and braking performance on ice and snow, the skid resistance, the turning performance can also be advantageously improved, and all the corners of each block are made obtuse to provide sufficient block rigidity. By increasing the height, it is possible to effectively prevent the deformation of the block and to improve the performance on snow and ice. Moreover, according to these, the rigidity of the block can be effectively increased, and the steering stability on a dry road surface and a wet road surface can be improved.

Preferably, the outline of the block is substantially hexagonal, and a plurality of sipes are formed in the block. Nearly hexagonal shaped blocks can provide better turning performance on snow and ice under more edge components, and due to the high rigidity of the block itself, increased performance on snow and ice. The improvement can be provided, and the plurality of sipes in the block can effectively contribute to the improvement of the on-ice performance as the basic performance of the studless tire.

Preferably, a sub-block defined by a sipe is provided in the block, and the density of the sub-block is increased at a central portion of the block. According to this, by extending a plurality of sipes in a block so as to intersect in a substantially lattice-like manner, the edges of the sipes can function sufficiently in the respective directions such as the front-rear direction and the lateral direction. In particular, the turning performance on ice can be greatly improved. In addition, by increasing the density of the sub-blocks, and thus the sipe density, in the central part of the block where melting water is particularly likely to occur during braking on ice, etc., the braking performance on ice, etc., under the water absorption of the sipe, is advantageously enhanced be able to.

By the way, the circumferential grooves extending in a zigzag manner are formed by three wide circumferential grooves extending substantially at the center position and each side position of the tread tread portion, and extending between these wide circumferential grooves. Then, in the case where it is composed of the sub-circumferential groove composed of the narrow portion and the wide portion alternately located in the circumferential direction, the three wide circumferential grooves provide excellent wet drainage performance, snow turning performance, etc. Under the action of the sub-circumferential groove, the edge components in the circumferential direction and the width direction of the block can be effectively increased while maintaining the rigidity of the block high. Can further improve the turning performance.

In this tire, the block is formed into a flat hexagonal shape that is long in the direction in which the inclined groove extending in a substantially step-like manner extends. It is possible to sufficiently secure the performance of the drainage function.

Preferably, the groove width of the narrow portion of the sub circumferential groove is in the range of 0.5 to 8.0 mm, more preferably in the range of 1.5 to 6 mm. That is, when the groove width is 0.5
If it is less than mm, it will be equivalent to the width of the sipe, and it will not be able to effectively contribute to the division of the block and the drainage function. If it exceeds 8.0 mm, it will be the same width as the wide circumferential groove. However, the negative rate becomes too large, and there is a possibility that the performance may be deteriorated due to a decrease in block rigidity.

[0014] More preferably, the sipe in each block is given the same direction as the inclined groove, so that the overall extending mode of each sipe is the inclined direction of the inclined groove. According to this, the inclination of the sipe can be approximately adjusted to the protruding shape of the tread's ground contact shape, and it can be effectively contributed to the improvement of traction on snow.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a development view of a tread pattern showing an embodiment of the present invention, in which 1 indicates a tread portion, and 2 indicates a tread tread portion.

Here, three wide circumferential grooves 3 and 4 having a substantially uniform width and extending in a circumferential direction in a zigzag manner are provided at substantially the center position and each side position of the tread tread portion 2, respectively. , Which also extend in a zigzag manner between the wide circumferential grooves and are alternately located in the circumferential direction, and the opening width is 0.5 to 8.0 mm, more preferably 1.5 to 6.0 m.
m, and two sub-circumferential grooves 5 each having a wide portion that can make the opening width equal to those of the wide circumferential grooves 3 and 4 are provided. At the end, in the figure, there is provided a respective inclined groove 6 extending substantially stepwise from the tread end toward the center of the tread in the opposite direction to each other and ending with the wide groove 3 at the center of the tread. The grooves 3, 4, 5, and 6 define a directional tread pattern composed of six block rows 7, 8, and 9 on the tread tread portion 2.

As shown in the drawing, in each of the inclined grooves 6 having a substantially step shape, both the tread surface equivalent portion and the depression equivalent portion have a downward slope from the tread tread edge toward the tread center. In particular, each of the blocks 10 and 11 of the block rows 7 and 8 between the circumferential grooves forms a flat hexagonal shape that is long in the direction in which the inclined grooves 6 extend. Each corner of the blocks 10 and 11 has an obtuse angle.

By the way, as shown in the drawing, each block 12 of the block row 9 partitioned on the side of the tread surface from the outermost circumferential groove 4 also has a substantially hexagonal shape which is flat under the same tendency as shown in the figure. It can be formed into a shape.

Each of the blocks 10, 11 and 12 partitioned in this manner has a block 10, 1 respectively.
A plurality of, for example, four sipes 13 extending substantially parallel to the circumferential edges of the blocks 1, 12 are formed linearly at substantially equal intervals, and are substantially aligned with any other edge of the blocks 10, 11, 12. A plurality of other sipes 14 extending in parallel and intersecting with the sipes 13 are also formed linearly, preferably,
The formation density of these sipes 14 is set to each block 10, 1
By increasing in the central area of 1,12, each sipe 1
The arrangement density of the sub-blocks 15 divided by 3 and 14 is increased in the central area.

According to the tread pattern configured as described above, under the action of the five circumferential grooves 3, 4, 5 extending in the circumferential direction in a zigzag manner and the inclined grooves 6 for specifying the directional pattern. Each block 1 has a substantially hexagonal shape while ensuring high drainage performance on wet road surfaces.
In combination with the action of the respective edge components 0, 11, and 12, the driving and braking performance, the skid resistance, and the turning performance on snow and ice can be greatly improved. , 12, the various performances, especially on ice, can be further enhanced.

[0021]

EXAMPLE In the example tire having a size of 195/65 R15, the negative ratio was 38.7%, and the average width of the wide circumferential groove 3 located at the center of the tread 2 was 8.5 m.
m, the average groove width of the other wide circumferential grooves 4 is 7.5 mm, the groove width of the narrow portion of the sub circumferential grooves 5 is 2.5 mm, and the groove width of the inclined groove 6 in the center area of the tread surface is reduced. 7.8 mm, 8.0 mm at the end of the tread surface, and the angle of the stepped inclined groove 6 corresponding to the tread surface with respect to the circumferential direction is about 7 mm.
5 °, the angle of the inclined groove itself with respect to the circumferential direction is set to about 45 °, and each sipe 1
When the opening width of 3, 14 is set to 0.5 mm, the feeling on snow and on ice, the braking performance on snow and on ice, the driving performance on snow, and the hydroplaning resistance on wet road surfaces are determined. The results of the index evaluation were as shown in Table 1.

Here, the conventional tire had the tread pattern shown in FIG. 2, and both the tire size and the negative rate were the same as those of the example tire. In addition, the index values in the table indicate large and excellent results.

[0023]

[Table 1]

Here, the feeling on snow is determined by comprehensively evaluating the braking performance, starting performance, straight running performance, and turning performance of the test coat on a snow-covered road surface. / H is determined by measuring the braking distance when the vehicle is fully braked, and the on-snow driving performance is determined by measuring the time required to travel a distance of 50 m on compacted snow.
The braking performance, starting performance, straight running performance, and turning performance of the test track on the icy road surface were determined by comprehensively evaluating the feeling. The braking performance on ice was determined by the braking distance when the icy ice was fully braked from 20 km / h. Was measured. The hydroplaning resistance performance on a wet road surface was determined by feeling evaluation of a critical speed at which a hydroplaning phenomenon occurred when the vehicle passed a wet road surface having a depth of 5 mm.

[0025]

Thus, according to the present invention, as is apparent from the above-described embodiment, excellent drainage performance is realized, and high driving and braking performances on snow and ice, respectively, are obtained. The turning performance on snow and ice can be greatly improved.

[Brief description of the drawings]

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

FIG. 2 is a development view of a tread pattern showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tread part 2 Tread tread part 3,4 Wide circumferential groove 5 Secondary circumferential groove 6 Inclined groove 7,8,9 Block row 10,11,12 block 13,14 Sipe 15 sub-block

Claims (7)

[Claims] 1. A plurality of circumferential grooves extending in a zigzag shape in a circumferential direction are provided in a tread tread portion, and inclined grooves extending substantially stepwise in opposite directions from respective tread tread ends toward the center of the tread surface. In the pneumatic tire having a directional tread pattern formed by forming a plurality of block rows on the tread tread portion by the circumferential grooves and the inclined grooves, each of the block rows partitioned between the circumferential grooves While making the outline shape of the block of a pentagon or more a polygon,
A pneumatic tire in which all corners of each block are made obtuse. 2. The pneumatic tire according to claim 1, wherein the outline of the block is substantially hexagonal, and a plurality of sipes are formed in the block. 3. The pneumatic tire according to claim 2, wherein sub-blocks defined by sipes are provided in the block, and the density of the sub-blocks is increased at a central portion of the block. 4. Three wide circumferential grooves are provided at substantially the center position and each side position of the tread tread portion, and the narrow circumferential grooves are alternately located in the circumferential direction between the wide circumferential grooves. The pneumatic tire according to any one of claims 1 to 3, wherein a sub-circumferential groove including a portion and a wide portion is provided. 5. The pneumatic tire according to claim 1, wherein the block has a flat hexagonal shape extending in a direction in which the inclined groove extends. 6. The groove width of the narrow portion of the sub circumferential groove is set to 0.5 to
The pneumatic tire according to claim 4 or 5, which has a range of 8.0 mm. 7. The pneumatic tire according to claim 2, wherein the sipe in each block is provided with a directionality in the same direction as the inclined groove.