JP2001294023A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve driving performance or the like in an advancing direction while suitably securing side skid resistant performance or the like in a width direction by scheming an arrangement of circumferential grooves and circumferential sipes. SOLUTION: Blocks 7 and 8 partitioned by the circumferential grooves 4 and width direction grooves 5 are provided circumferentially aligned in a tread part 2, and circumferential sipes 11 and 12 are formed in the blocks 7 and 8. The circumferential groove 4 has a first groove part 4A, and a second groove part 4B circumferentially adjacent to the first groove 4A and formed offset in the width direction. Circumferential sipes 11B and 12B of the blocks 7 and 8 partitioned by the second groove 4B are formed offset with respect to circumferential sipes 11A and 12B of the blocks 7 and 8 partitioned by the first groove 4A in the same direction as the offset direction of the second groove 4B with respect to the first groove 44.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pneumatic tire,
In particular, the present invention relates to a pneumatic tire having a tread portion having a block pattern such as a studless tire (snow tire).

[0002]

2. Description of the Related Art A pneumatic tire of this type is disclosed, for example, in JP-A-11-342708. This pneumatic tire has a plurality of longitudinal grooves (circumferential grooves) extending in the tire circumferential direction on a tread tread portion.
And a number of transverse grooves (width-direction grooves) intersecting them, and a number of blocks defined by these grooves. Each of the blocks has a sipe extending in the width direction. In addition, a sipe extending in the circumferential direction is also formed in the shoulder block disposed on the widthwise outer portion of the tread portion.

Further, the vertical groove has a bend angle with respect to the equator line (tire center) and is formed in a zigzag shape that is alternately left and right in the tire circumferential direction.

[0004]

In the pneumatic tire of the prior art, the driving performance (traction performance) and braking performance in the straight running direction on ice and snow are ensured by the circumferential side edges of the blocks defined by the lateral grooves. The lateral edges of the blocks separated by the vertical grooves secure the anti-slip performance and maneuvering performance, and the edge effect of the blocks separated by the width sipe enhances the driving performance in the straight direction. In addition, the edge effect of the shoulder block divided by the circumferential sipe enhances the skid resistance and the like in the width direction.

Further, by forming the vertical grooves in a zigzag shape, a traction effect is exerted on the side edges in the width direction of the blocks defined by the vertical grooves, so that the driving performance and the braking performance are improved not only by the horizontal grooves but also by the vertical grooves. Could be done. However, since the flutes are formed in a zigzag shape, the performance in the width direction such as skid resistance, steering performance, etc. may decrease. Even if auxiliary circumferential sipe is formed, sufficient effect is expected. It was hard. Further, although the circumferential groove is formed in a zigzag shape, the circumferential sipe is formed substantially parallel to the equator line, so that a partial area of the shoulder block between the circumferential sipe and the vertical groove is formed. The lateral width expands and contracts in the circumferential direction, and a change in the rigidity may cause uneven wear.

[0006] As another index indicating the running performance of the tire, there is wandering resistance performance (running over a rut), and this performance can be improved by lowering the rigidity of the shoulder block to adapt to the step of the rut. Are known. However, from the perspective of skidding resistance,
If the rigidity of the shoulder block is low, the edge effect due to the circumferential sipe will not be sufficiently exerted, and uneven wear, block breakage and the like may be caused. That is, the anti-skid performance and the wandering resistance have a certain contradictory relationship, and it is important to balance these in improving the running performance of the tire as a whole.

The present invention has been made in view of the above-mentioned circumstances, and by arranging the longitudinal grooves (circumferential grooves) and the circumferential sipe, it is possible to keep the sliding resistance in the width direction and the like in a straight line. It is an object of the present invention to provide a pneumatic tire capable of improving driving performance in directions and the like and preventing uneven wear of a block.

[0008]

The present invention employs the following technical means to achieve the above object. That is, the present invention provides the tread portion 2 with the circumferential groove 4 and the width groove 5.
In a pneumatic tire in which circumferential blocks 11, 12 are provided in blocks 7, 8, which are partitioned in the circumferential direction, the circumferential grooves 4 are formed.
Has a first groove portion 4A and a second groove portion 4B formed adjacent to the first groove portion 4A in the circumferential direction and offset in the width direction, and is partitioned by the second groove portion 4B. 7, 8 circumferential sipe 11B, 12B
With respect to circumferential sipes 11A and 12A of blocks 7 and 8 defined by groove 4A, the first groove
It is characterized by being formed so as to be offset in the same direction as the offset direction with respect to the groove 4A.

According to this, the side edges in the width direction of the blocks 7 and 8 defined by the circumferential groove 4 and the circumferential sipe 1
The edge effect at the divided portion of the blocks 7 and 8 divided by the blocks 1 and 12 can appropriately secure the lateral slip resistance and the like in the width direction, and further, the first and second groove portions 4A mutually offset in the width direction. , 4B, the circumferential side edges of the blocks 7, 8 which are circumferentially adjacent to each other are partially opposed and exposed, so that the portions can be effectively improved to improve the driving performance and the braking performance. It is possible to work.

Further, since the first and second grooves 4A, 4B and the circumferential sipes 11A, 11B, 12A, 12B are offset from each other in the width direction, these grooves 4A, 4B and circumferential sipes 11A, 11B, 12A. , 12B are arranged over a wide area in the width direction, and there is an effect that the skid resistance and the steering performance can be further improved. That is, by the characteristic arrangement of the circumferential groove 4 and the circumferential sipe as described above,
Driving performance and braking performance can be improved while ensuring skid resistance and the like.

The circumferential sipes 11B and 12B of the blocks 7 and 8 defined by the second groove 4B are connected to the second groove 4B.
By offsetting in the same direction as B,
The second grooves 4A, 4B and the respective circumferential sipes 11A, 11B,
The partial lateral width of the blocks 7, 8 sandwiched between the blocks 12A, 12B can be made substantially constant in the circumferential direction, and the rigidity of the portions can be made substantially uniform in the circumferential direction. As a result, uneven wear of the blocks 7 and 8 can be suitably prevented. In order to reliably obtain this effect, the offset amount L1 of the second groove 4B and the offset amounts L2, L3 of the circumferential sipes 11B, 12B of the blocks 7, 8 defined by the second groove 4B are determined. Are preferably set to substantially the same size.

The present invention is characterized in that the block is a tread portion 2
The shoulder blocks 8 are disposed on both outer sides in the width direction. Furthermore, in this case, the widthwise outer surface of the shoulder block 8 and the circumferential sipe 11A,
It is preferable to adopt a configuration in which the intervals α3 and α4 with respect to 11B are alternately enlarged and reduced in the circumferential direction. With such a configuration, the rigidity of the widthwise outer portion of the shoulder block 8 varies alternately in the circumferential direction, and the circumferential sipes 11A and 11B are formed.
By improving the lateral slip resistance and the steering performance, the shoulder blocks 8 having high rigidity at the outer side in the width direction and the low shoulder blocks 8 are alternately arranged in the circumferential direction in a well-balanced manner. It can be secured.

According to the present invention, the first groove 4A or the second groove 4B
A plurality of circumferentially convex portions 15 are formed on the widthwise inner edge of the block 8 disposed on the outer side in the width direction, and are disposed on the inner side in the width direction. The outer edge in the width direction of the block 7 to be provided is formed in a straight shape in the circumferential direction. According to this, the block 7 having a high contribution with respect to the skid resistance is provided.
By forming the widthwise outer edge of the block 8 in a straight shape in the circumferential direction, the skid resistance can be suitably secured, and the widthwise inner edge of the block 8 which contributes less than the widthwise outer edge of the block 7 can be formed. The formation of the plurality of circumferential projections 15 allows the portion to function suitably for driving performance and braking performance.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a tread portion 2 of a pneumatic tire 1 according to an embodiment of the present invention exemplified by a studless tire. The tread portion 2 is formed with a pair of left and right center main grooves 3, 3 extending in the circumferential direction with the equator line (center of the tread portion 2) CL interposed therebetween. A pair of left and right side main grooves (circumferential grooves according to the present invention) 4, 4 are formed, and lateral grooves (width grooves) arranged orthogonal to the equator line CL and extending in the width direction. Are formed at intervals in the tire circumferential direction.

A center block 6 is formed so as to protrude on the equator line CL between the left and right center main grooves 3, 3, and a pair of left and right sides is provided between the center main grooves 3, 3 and the side main grooves 4, 4. The block 7 is formed to be raised, and the side main groove 7 is formed.
A pair of right and left shoulder blocks 8 is formed to protrude outward in the width direction. The blocks 6, 7, 8 are arranged in the circumferential direction by being defined by the lateral grooves 5, 5,.... In FIG. 1 showing the right half of the tread portion 2, the center main groove 3 is formed in a substantially straight line in the circumferential direction, whereas the side main groove 4 is aligned with the equator line CL. 1st groove part 4A arranged substantially parallel
A second groove substantially parallel to and circumferentially adjacent to the first groove portion 4A and further offset outward by the dimension L1 in the width direction.
It has grooves 4B alternately in the circumferential direction. Further, the first and second groove portions 4A and 4B are continuously provided in the circumferential direction via the lateral groove 5.

The outer surfaces in the width direction of each shoulder block 8 are arranged substantially in a row in the circumferential direction, and the center main groove 3 is formed substantially linearly, so that the first and second groove portions are formed. Side block 7 partitioned by 4A and 4B
The shoulder block 8 is formed such that a wide one and a narrow one are alternately arranged in the circumferential direction. In the above configuration, the driving performance and braking performance in the straight running direction on an icy road or the like are ensured by the circumferential side edges of the blocks 6, 7, and 8 defined by the lateral grooves 5, and the circumferential center main groove 3, the side. The sides in the width direction of each of the blocks 6, 7, 8 separated by the main groove 4 ensure the skid resistance and the steering performance.

At the open ends (circumferential ends) of the first and second grooves 4A and 4B in the side main groove 4, a part of the circumferential side edges of the side block 7 and the shoulder block 8 adjacent thereto is formed. Since these portions are opposed to each other and are exposed in the circumferential direction, the traction effect and the like are more effectively exhibited than the other side edge portions, so that the driving performance and the braking performance can be improved. Each center block 6 has a plurality of sipe 10 extending in the width direction in the circumferential direction (3 in the figure).
A plurality of (two in the illustrated example) sipe 11 extending in the width direction are formed in each shoulder block 8 in the width direction, and one sipe 11 in the width direction is provided in the side block 7 on the outside in the width direction. 12 has a plurality (3
The sipe 13 in the width direction of the book is formed.

Center block 6 and side block 7
Each of the widthwise sipes 10 and 13 formed in each of the blocks 6 and 7 causes the blocks 6 and 7 to bite into ice and snow roads and to suck and suck a water film.
Since the discharge action can be expected, the driving performance in the straight direction,
The braking performance can be enhanced, and the anti-skid performance and the steering performance can be enhanced by the above-described operation of the circumferential sipes 11 and 12 formed in the side block 7 and the shoulder block 8. Here, the circumferential sipe 11B, 12B of the side block 7 and the shoulder block 8 defined by the second groove 4B is the same as the circumferential sipe 11A, 12A of the side block 7 and the shoulder block 8 defined by the first groove 4A. On the other hand, the second groove 4B
The first groove portion 4A is offset in the same direction as the offset direction with respect to the first groove portion 4A, that is, outwardly in the width direction by dimensions L2 and L3.

More specifically, the offset amount L1 of the second groove 4B and the offset amounts L2, L3 of the circumferential sipes 11B, 12B are set to substantially the same size. 4A, 4B and circumferential sipe 11
A, 12A, 11B, 12B, the partial width α1, of the side block 7 and the shoulder block 8 sandwiched between them.
α1 ′ and α2 are substantially constant in the circumferential direction. Therefore, the partial stiffness of the blocks 7 and 8 is made substantially constant in the circumferential direction, and uneven wear is prevented.

The first and second grooves 4 adjacent to each other in the circumferential direction
A, 4B and circumferential sipes 11A, 11B, 12A, 1
2B are offset from each other in the width direction, so that these grooves 4A, 4B and circumferential sipes 11A, 11A,
1B, 12A, and 12B are arranged in a wide range in the width direction, thereby effectively functioning for anti-skid performance, steering performance, and the like. The shoulder block 8 has a circumferential sipe 11 extending from the outer surface in the width direction to the outer side.
The gaps α3 and α4 to A are narrow and wide alternately in the circumferential direction. In other words, the shoulder blocks 8 having a high edge rigidity and the low shoulder blocks 8 are alternately arranged in a well-balanced manner. It has become.

With such a configuration, the circumferential sipe 11
With A, wandering resistance is secured while anti-skid performance is improved, and damage such as uneven wear and chipping of blocks is prevented as much as possible. Also, the wandering resistance can be improved by arranging the wide shoulder blocks 8 and the narrow shoulder blocks 8 alternately in the circumferential direction so as to have a difference in rigidity.
In addition, the width direction sipes 10 and 13 and the circumferential direction sipes 11 and 1
2 are each formed in a wave shape or a zigzag shape, and the driving performance and the braking performance can be improved by the width direction component, and the anti-skid performance and the steering performance can be improved by the circumferential component.

On the inner edge in the width direction of the shoulder block 8, a large number (5 in the example in the figure) of mountain-shaped projections 15 are formed in the circumferential direction, while the outer edge in the width direction of the side block 7 is straight. Is formed. Here, with respect to the skid resistance, since the outer edge contributes more than the inner edge in the width direction of the side block 7 and the shoulder block 8, the outer edge in the width direction of the side block 7 is formed into a circumferential straight shape. Suitable for improving skid resistance,
By forming a large number of protrusions 15 on the widthwise inner edge of the shoulder block 8 whose contribution is lower than this portion, the structure is made to work effectively on the driving performance and the braking performance.

FIG. 3 shows a second embodiment of the present invention. In this embodiment, the widthwise inner edge of the shoulder block 8 and the side block 7 adjacent to each other in the widthwise direction with the second groove 4B interposed therebetween. Many circumferential projections 15 on the outer edge in the width direction
In order to improve the traction performance and the braking performance by forming the first groove portion 4A, the widthwise inner edge of the shoulder block 8 and the widthwise outer edge of the side block 7 adjacent to each other across the first groove 4A are formed in a straight shape. Therefore, consideration has been given to effectively work for the skid resistance.

That is, by alternately disposing the blocks 7 and 8 having the convex portions 15 and the blocks 7 and 8 formed in a straight shape in the circumferential direction, the driving performance and the like can be improved in a well-balanced manner.
The anti-skid performance and the like can be achieved.
The other configuration is the same as that of the above-described first embodiment, and thus the detailed description is omitted. The present invention can be appropriately changed in design without being limited to the above-described embodiment. For example, one or three or more circumferential sipes 11 formed on the shoulder block 8 may be provided. A directional sipe may also be formed. In addition, the side block 7 does not form the circumferential sipe 12 but
A configuration in which only one is formed may be used.

The circumferential and width sipes of each of the blocks 6, 7, 8 can be formed not only in a wave shape or the like but also in a straight line. In the example shown in the figure, a closed type in which both ends of the sipes are terminated in the block. Although it is a sipe, it may be an open type sipe in which both ends of the sipe are open to the width direction groove or the circumferential direction groove, or one end is open to the width direction groove or the circumferential direction groove, and the other end is inside the block. It may be a closed semi-open type sipe. The number of circumferential projections 15 formed on the shoulder block 8 or the side block 7 is as follows.
The present invention is not limited to the example shown in the drawings, and it is sufficient that two or more units are provided.

First and second grooves 4A, 4B of side main groove 4
May be arranged to be inclined with respect to the equator line CL.
In this case, the circumferential sipes 11 and 12 also have the first and second groove portions 4.
It may be inclined with respect to the equator line CL so as to be substantially parallel to A and 4B. Similarly to the side main groove 4, the center main groove 3 may be configured by offsetting the first and second groove portions adjacent in the circumferential direction in the width direction. In this case, the offset amount is determined by the side main groove. 4 and circumferential sipes 11,
It is preferable to set the same size as 12.

[0027]

As described above in detail, according to the present invention, the first and second grooves constituting the circumferential groove are arranged with offset and the circumferential sipes are offset with respect to this. , It is possible to improve the driving performance in the straight running direction while securing the anti-skid performance in the width direction, etc.,
In addition, uneven wear of the block can be prevented.

[Brief description of the drawings]

FIG. 1 is a plan view showing a right half of a tread of a pneumatic tire according to a first embodiment of the present invention.

FIG. 2 is a plan view showing the entire width of the tread.

FIG. 3 is a plan view showing a right half of a tread of a pneumatic tire according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Center main groove 4 Side main groove (circumferential groove) 5 Lateral groove (width direction groove) 6 Center block 7 Side block 8 Shoulder block 11 Circumferential sipe 12 Circumferential sipe

Claims (5)

[Claims] A block (7, 2) defined by a circumferential groove (4) and a width direction groove (5) in a tread portion (2).
In the pneumatic tire in which the blocks (7, 8) are provided with the circumferential sipes (11, 12) in the circumferential direction, the circumferential grooves (4) are formed in the first direction. A groove (4A) and a second groove (4B) circumferentially adjacent to the first groove (4A) and offset in the width direction, and are formed by the second groove (4B). Blocks to be partitioned (7,
The circumferential sipe (11B, 12B) of (8) is arranged on the second groove (4B) with respect to the circumferential sipe (11A, 12A) of the block (7, 8) partitioned by the first groove (4A). The pneumatic tire is formed so as to be offset in the same direction as the offset direction with respect to the first groove portion (4A). 2. An offset amount (L1) of the second groove portion (4B) and an offset amount (L1) of a circumferential sipe (11B, 12B) of a block (7, 8) partitioned by the second groove portion (4B). L2, L3) are set to substantially the same dimensions. 3. The pneumatic tire according to claim 1, wherein the block is a shoulder block disposed on a widthwise outer side of the tread portion. 4. The interval (α3, α4) between the widthwise outer surface of the shoulder block (8) and the circumferential sipe (11A, 11B) formed on the shoulder block (8) is alternately enlarged and reduced in the circumferential direction. 4. The method according to claim 3, wherein
A pneumatic tire according to claim 1. 5. The first groove (4A) or the second groove (4A).
B), and blocks (7, 8) adjacent in the width direction with the plurality of circumferential protrusions (15) being provided on the width-direction inner edge of the block (8) disposed outside in the width direction. Forming
2. The pneumatic tire according to claim 1, wherein an outer edge in the width direction of the block (7) disposed on the inner side in the width direction is formed in a circumferential straight shape. 3.