JPH1016517A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the braking performance and the driving performance on an icy/snowy road without reducing a contact area at the tread surface. SOLUTION: A plurality of blocks 3a, 3b, 4 having block ends of zigzags 9, 10 extending in a step shape are provided on a tire center area CA, a middle area MA, and a shoulder area SA of a tire tread surface 1. A plurality of transverse sipes 11, 13 to be opened in corner parts 12, 14 of a ridge of the zigzags 9, 10 are formed on the blocks 3a, 3b, 4. The transverse sipes 11, 13 have a zigzag part 16 to be opened in a zigzag manner on the block surface. Among the transverse sipes 11, 13, the transverse sipe formed on each end part in the circumferential direction of the tire in a unit block in the tire center are CA and the middle area MA is the transverse sipe 11a with single opening in which one end is opened in the corner part of the zigzag of the block end, and the other end is closed, while the transverse sipe formed in a center part in the circumferential direction of the tire is the transverse sipe 11b with double openings opened at both ends.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pneumatic tire suitable for icy and snowy roads, and more particularly to a studless tire having improved braking and driving performance on icy and snowy roads without reducing the ground contact area.

[0002]

2. Description of the Related Art In recent years, so-called studless tires have adopted various tread patterns in order to provide excellent snow performance and ice performance on icy and snowy roads. Especially on ice and snow roads, the scratching effect, that is, the edge effect is an important factor. To secure this effect, a zigzag main groove is formed on the tread surface, and many sipes are arranged on blocks formed on the tread surface. Measures have been taken.

[0003]

However, when a large number of zigzag-shaped main grooves are formed, the contact area decreases, and as a result, ice performance, wear performance and noise performance deteriorate.

On the other hand, in the conventional sipe arrangement, as shown in FIG. 3, a sipe end opening 17 is opened to a straight block end 18, and an edge formed by the sipe opening is formed on a road surface. On the other hand, the edge effect was not effectively utilized because it was hard to be caught and the sipe was hard to open. In addition, in FIG. 3, 19 is a tire tread surface, and 20 is a block. CA is a tire center area, MA is an intermediate area, SA is a shoulder area, e is a ground end, 21 is a main groove, and 22 is a lateral groove. 23 is a horizontal sipe. In addition, it is desirable that the edge effect is exerted not only in one direction but also in various directions in order to improve snow performance and ice performance, but conventionally, such points have not been sufficiently considered.

An object of the present invention is to provide a pneumatic tire capable of improving braking performance and driving performance on icy and snowy roads without reducing a contact area on a tread surface.

[0006]

As a result of intensive studies to solve the above-mentioned problems, a zigzag block end shape line is formed, and a plurality of horizontal sipes are formed in the block at the corners of the zigzag valley. The present invention is based on the finding that the lateral sipe has a zigzag portion that opens in a zigzag shape on the surface of the block, so that the edge effect on ice and snowy roads can be increased without reducing the ground contact area. Was completed.

That is, according to the first aspect of the present invention, a plurality of blocks having zigzag block ends are provided on the tire tread surface, and a plurality of horizontal sipes are formed in the blocks at the corners of the zigzag valleys. The lateral sipe has a zigzag portion that opens in a zigzag shape on the block surface.

Accordingly, the number of edges can be increased without reducing the contact area on the tread surface, and the edge formed at the sipe end can be more effectively utilized. In addition, since the horizontal sipe has a zigzag portion that opens in a zigzag shape on the surface of the block, the edge effect of the sipe itself is improved, and at the same time, the edge effect having various directions can be given to the sipe itself. In addition, the edge effect can be synergistically improved because it can also be transmitted to the edge effect of the zigzag block end. In addition, since the edge has lower rigidity than other portions, the edge is easily cut into a snowy road, and the edge effect is further improved. Further, since the sipe is opened at the corner of the zigzag valley at the end of the block, the sipe is easily opened, and as a result, there is an effect that snow clogged in the lateral groove is easily removed.

In the horizontal sipe having the zigzag portion according to the first aspect, at least one of the zigzag valleys at the end of the block is opened. Further, the other end of the horizontal sipe may be opened to the other block end. However, in order to synergistically exert the edge effect of the zigzag block end and the edge effect of the sipe opening at the corner of the zigzag valley while securing the rigidity of each block, in the unit block, It is important to combine a lateral sipe with both openings and a lateral sipe with one opening. In this case, at both ends in the tire circumferential direction in the unit block, one end is opened at a zigzag corner of the block end, and the other end is provided with a single-opened lateral sipes closed at the other end. It is preferable to provide a horizontal sipe having two openings at both ends in the center.

That is, according to a second aspect of the present invention, in the lateral sipes of the first aspect, one end is opened at a zigzag corner portion of the block end and the other end is closed at both ends in the tire circumferential direction within the unit block. 2. The pneumatic tire according to claim 1, further comprising: a single opening lateral sipe; and a double opening horizontal sipe having both ends opened in a center portion of the unit block in the tire circumferential direction. 3. As a result, the rigidity of both ends in the unit block is increased, so that there is an effect of suppressing uneven wear while maintaining ice and snow road performance.

In the present invention, the zigzag at the block end may be any as long as it extends in the tire circumferential direction or the tire width direction. Therefore, a zigzag extending in an oblique direction located in the middle between the tire circumferential direction and the tire width direction, that is, both the tire circumferential direction and the width direction is included. In addition, the “zigzag” of the block end referred to in the present invention
The term “step” is most preferable from the viewpoint of securing the ground contact area and improving the edge action, but is a concept including a saw-tooth shape and a wavy shape. Further, in the present invention, a sipe having at least one opening in the zigzag valley at the block end and having a zigzag portion is an essential component, but a sipe or zigzag portion not opening at the zigzag valley at the block end is provided. It does not exclude the inclusion of sipes that have not been done. Therefore, it is also possible to combine a horizontal sipe that opens in the zigzag valley at the block end with a horizontal sipe that does not open, and a sipe that has a zigzag portion and a sipe that does not have a zigzag portion. They can be combined.

[0012]

FIG. 1 is a schematic view of a tread pattern showing an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a tire tread surface, and reference numeral 2 denotes an inclined lateral groove formed in a substantially N shape so as to cross a block 3a in a tire center area CA and blocks 3b in an intermediate area MA located on both sides thereof. The lateral grooves 2 are blocks 4 and 4 of the shoulder area SA.
It is connected to the end lateral groove 5 which divides each other, and reaches both grounding ends e and e of the tire tread surface 1. The block 3a in the tire center area CA is formed as two blocks partitioned by horizontal grooves 2, 2, vertical grooves 6, and a central inclined groove 7, as shown. Block 3b of the intermediate area MA
Are provided on both sides of the block 3a in the tire center area CA by being partitioned by the lateral grooves 2, 2, the vertical groove 6, and the end inclined groove 8.

The tire center area CA and the intermediate area MA
As shown in the drawing, a zigzag 9 extending stepwise in both the tire width direction and the tire circumferential direction, that is, in an oblique direction, is formed at each block end of the blocks 3a and 3b. Also, as shown in the drawing, the above-mentioned blocks 3a, 3b are also provided at the respective block ends of the block 4 in the shoulder area SA.
A zigzag 10 extending stepwise in the same direction as the above is formed. This step-shaped zigzag 9 and zigzag 10
Are formed along an inclined lateral groove 2 formed in a substantially N-shape. Therefore, the block 3a in the tire center area CA has a zigzag 9 on the side of the inclined horizontal groove 2, and is a linear block end on the side of the vertical groove 6 and the center inclined groove 7. The block 3b of the intermediate area MA also has a zigzag 9 on the side of the inclined horizontal groove 2 and a linear block end on the side of the vertical groove 6 and the end inclined groove 8. The block 4 in the shoulder area SA has a zigzag 1 on the side of the inclined horizontal groove 2.
0, but a linear block end is formed on the side of the end inclined groove 8 and the end lateral grooves 5 and 5.

Reference numeral 11 denotes a lateral sipe that opens at the corner 12 of the valley of the zigzag 9 of the blocks 3a and 3b in the tire center area CA and the intermediate area MA. Reference numeral 13 denotes a lateral sipe that opens at the corner 14 of the valley of the zigzag 10 of the block 4 in the shoulder area SA. Each of the horizontal sipes 11 and 13 has a zigzag portion 16 that opens in a zigzag shape on the block surface 15.

Therefore, the edges of both the block and the sipe can be increased without reducing the ground contact area on the tread surface, and the lateral sipe is a sipe opening at the corner of the zigzag valley at the end of the block. And the horizontal sipe edge effect works effectively. Moreover, since the lateral sipe has a zigzag portion which opens in a zigzag shape on the block surface, the sipe length is increased by the zigzag structure, and the edge effect of the sipe itself is improved and various directions are provided. The edge effect can be imparted to the sipe itself, and particularly the edge effect can be transmitted to the edge of the zigzag block end, so that the edge effect is synergistically improved. Therefore, ice performance and snow performance can be improved without deteriorating wear performance, noise performance, and the like.

In particular, in the present embodiment, as shown in FIG. 2, the blocks 3a, 3a in the tire center area CA are located at both ends in the tire circumferential direction in the unit block, and one end is located at the corner of the zigzag of the block end. The tire is provided with a single-sided horizontal sipe 11a which is open and the other end is closed, and a double-sided horizontal sipe 11b which is open at both ends is provided at the center in the tire circumferential direction in the unit block. As a result, the rigidity of both ends in the unit block is increased, so that the effect of suppressing uneven wear and chipping of the block can be achieved while maintaining the performance on ice and snow roads. Also, a lateral sipe 1 that does not open at the zigzag corner of the block end
1c is formed between the horizontal sipe 11a and the horizontal sipe 11b, or between the horizontal sipe 11a and the horizontal sipe 11a, which is opened at the corner of the zigzag at the block end. And chipping of blocks can be prevented. Although FIG. 2 illustrates the blocks 3a and 3a in the tire center area CA, the same applies to the block 3b in the intermediate area MA.

The present invention is not limited to the above embodiment. For example, in FIG. 1, the horizontal sipe has a wavy zigzag portion, but may have a saw blade shape or the like. As described above, a horizontal sipe having no zigzag portion can be further formed. Further, in the above embodiment, the direction of the lateral sipe is parallel to the tire width direction, but may be formed in an intermediate direction between the tire width direction and the tire circumferential direction, that is, in an oblique direction.

Further, in the present embodiment, the present invention is applied not only to the blocks in the tire center area CA and the intermediate area MA but also to the blocks in the shoulder area SA. is there. Also, the shape of the block is not particularly limited, and the lateral grooves are not N-shaped as in the present embodiment, but are divided into V-shaped and W-shaped lateral grooves in addition to a normal lateral groove parallel to the tire width direction. It can be used as a block.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings, taking a preferred embodiment as an example. Note that the present invention is not limited to the present embodiment. In the present Example and Comparative Example, a tire of the present invention and a conventional tire having the following configurations were prepared.

(Tire of the present invention) Tire size: 185 / 70R14 Tread pattern: FIG. 1 Sipe density: 0.159 Tread rubber hardness (JIS A): 55 (conventional tire) Tire size: 185 / 70R14 Tread pattern: FIG. 3 Sipe Density: 0.108 Tread rubber hardness (JIS A): 55

The following ice performance and snow performance were tested on a normal passenger car (1800 cc) equipped with each of the above tires. The test method conforms to JATMA regulations.

(Test on Ice) Feeling of braking effect: Two drivers get on the vehicle, perform the test twice, evaluate the score of the feeling of braking effectiveness by feeling, and take the average. A score of 5.0 out of 8 is a practically acceptable range. Braking distance: It is shown as the distance from 40 km / h to stopping with full brake. The evaluation result is obtained by calculating the reciprocal of the stopping distance, and converting the reciprocal of the stopping distance of the conventional tire to a reference value of 100 and expressing the result by an index. The higher the number,
Ice performance is good. Acceleration time: Evaluated by the time required to reach 0 to 30 km / h. The evaluation result is obtained by calculating the reciprocal of the acceleration time and converting the reciprocal of the acceleration time of the conventional tire to a reference value of 100 and converting it to an index. The higher the value, the better the ice performance.

(Test on a snow covered road) Feeling of braking effect: The same as in the test on ice. Braking distance: Shown as the distance from 30 km / h to the stop with full brake. The evaluation result is obtained by calculating the reciprocal of the stopping distance, and converting the reciprocal of the stopping distance of the conventional tire to 100, and displaying the result as an index. The larger the value, the better the snow performance. Acceleration time: Evaluated by the time required to reach 0 to 20 km / h. The evaluation result is obtained by calculating the reciprocal of the acceleration time and converting the reciprocal of the acceleration time of the conventional tire to a reference value of 100 and converting it to an index. The higher the value, the better the snow performance

(General Road Test) DRY Driving Stability: Shown by the driver's feeling evaluation during normal road running. Two drivers each perform a test,
The average of the scores of the two persons is shown. A score of 5.0 out of 8 is a practically acceptable range. WET steering stability: It is shown by feeling evaluation of a driver traveling on a normal road surface in a watered state (a road surface simulated after rain). The test was conducted by two drivers, respectively, and the average of the scores of the two drivers is shown. On a perfect score of 8
5.0 or more is a practically acceptable range. Pattern noise: Normally, noise during traveling on the road is indicated by the driver's feeling evaluation. The test was conducted by two drivers, respectively, and the average of the scores of the two drivers is shown. On a perfect score of 8
5.0 or more is a practically acceptable range. Abrasion resistance: A tire whose groove depth has been measured in advance is mounted on an automobile, and the vehicle travels with two passengers. After traveling 12000 km while changing the mounting position every 2000 km, the groove depth is measured, and the amount of wear is determined from the difference between the groove depths before and after traveling. The evaluation result is obtained by calculating the reciprocal of the amount of wear, and converting the reciprocal of the amount of wear of the conventional tire to a reference value of 100 and converting the result to an index. The larger the value, the better the wear resistance performance. Note that the tire pressures are all specified by the vehicle.

[0025]

[Table 1]

As shown in Table 1, the tire of the present invention has improved ice performance and snow performance as compared with conventional tires while ensuring steering stability, noise performance, and wear resistance.
It can be seen that the synergistic edge effect of zigzag blocks and lateral sipes works well.

[0027]

According to the present invention, the edge effect on snowy and snowy roads can be increased without reducing the ground contact area, so that the braking and braking on the snowy and snowy roads can be performed while the block rigidity is reduced, wear is easy, and pattern noise is avoided. Driving performance can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic view of a tread pattern showing one embodiment of the present invention.

FIG. 2 is a plan view showing a unit block in the tire center area.

FIG. 3 is a schematic view of a tread pattern showing an embodiment of the related art.

[Explanation of symbols]

 Reference Signs List 1 tire tread surface 2 lateral groove 3a block 3b block 4 block 5 end lateral groove 6 vertical groove 7 center inclined groove 8 end inclined groove 9 zigzag 10 zigzag 11 lateral sipes 12 corners 13 lateral sipes 14 corners 15 block surface 16 zigzag parts CA Tire center area MA Intermediate area SA Shoulder area e Grounding end

Claims (2)

[Claims] 1. A tire tread surface includes a plurality of blocks having zigzag block ends.
A pneumatic tire, wherein a plurality of horizontal sipes are formed at the corners of the zigzag valleys, and the horizontal sipes have zigzag portions that open in a zigzag shape on the block surface. 2. The lateral sipe of claim 1, wherein one end is opened at a zigzag corner of the block end and the other end is closed at both ends in the tire circumferential direction within the unit block. 2. The pneumatic tire according to claim 1, further comprising: a central portion in the tire circumferential direction within the unit block, and a lateral sipe having both openings opened at both ends.