JP2002274126A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve both draining performance and ice performance concerning a tire for winter. SOLUTION: A pair of peripheral direction main grooves 3, a peripheral direction auxiliary groove 4 and a plurality number of inclined grooves 7 are provided, block rows are respectively divided between the peripheral direction auxiliary groove 4 and each of the peripheral direction main grooves 3, two rows of center block rows 5 are formed, shoulder block rows 6 are respectively formed on tire cross direction outside of both of the peripheral direction main grooves 3, a plurality number of sipes are respectively provided on blocks 5a, 5b, 6a constituting each of the block rows 5, 6, each of the blocks 5a, 5b constituting the respective center block rows 5 are made roughly hexagonal and each of the blocks 6a constituting the shoulder block rows 6 is made slender and constricted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly to a winter tire, and particularly to a technique for improving drainage performance together with performance on ice and snow.

[0002]

2. Description of the Related Art As a conventional tire capable of exerting good performance on ice and snow in a well-balanced manner, there is a tire having a tread pattern as illustrated in a development view in FIG. 2, and a snow tire is continuous in a circumferential direction. Conventionally, a combination of a zigzag groove and a linear groove and a block having a lateral groove extending in the tire width direction is used.

[0003]

However, all of such conventional tires have a point-symmetric tread pattern, and the extending angle of the lateral groove with respect to the tread center is naturally limited. Since the circumferential zigzag grooves are unavoidable in order to ensure the driving performance and braking performance of the vehicle, there is a problem that it is difficult to ensure high drainage performance on wet road surfaces.

An object of the present invention is to solve such problems of the prior art, and an object of the present invention is to adopt a so-called directional pattern to achieve high drainage performance. It is still another object of the present invention to provide a pneumatic tire capable of further improving performance on ice and snow.

[0005]

A pneumatic tire according to the present invention has a pair of circumferential main grooves extending in a zigzag manner in a tire circumferential direction, and a pair of circumferential main grooves. A circumferential sub-groove extending in the tire circumferential direction at the inner side in the width direction and extending in a direction away from the tread center from below to above in a front view of the tire in a mounting posture to the vehicle from the circumferential sub-groove. Then, a plurality of inclined grooves that are open at the tread tread edge are provided, and a block row is partitioned between the circumferential sub-groove and each circumferential main groove to form two rows of center block rows. The shoulder block rows are formed on the outer side in the tire width direction of both circumferential main grooves, and a plurality of sipes are provided in each of the blocks constituting each block row, and each block constituting each center block row. , Together with the generally hexagonal shape, the blocks constituting the shoulder block row, is obtained by an elongated constricted shape.

[0006] In the pneumatic tire of the present invention, a pair of circumferential main grooves and circumferential sub-grooves are provided in the central region in the tire width direction to form two center block rows, whereby each center block row is formed. Each of the constituent blocks plays a role of securing a sufficient contact area in the center area in the tire width direction, so that they exhibit excellent driving performance and braking performance both on a dry road surface and on a road surface with a low friction coefficient. As well as the two center block rows serve to separate the left and right treads in the tire width direction, water can be diverted left and right on wet road surfaces,
Thereby, excellent drainage performance can be exhibited.

In addition, since both the pair of circumferential main grooves and the circumferential sub grooves extend in a zigzag manner in the tire circumferential direction, a conventional circumferential main groove extending linearly in the tire circumferential direction. In comparison with the grooves, the block edge component which is dominant with respect to the tire longitudinal force can be increased in each of the blocks located on the left and right of the circumferential main groove and the circumferential sub groove, and thereby, on the icy and snowy road surface. , Driving performance and braking performance, that is, performance on ice and snow can be secured at a high level.

By providing a plurality of inclined grooves,
It is possible to sufficiently secure a dominant block edge component with respect to the tire front-rear force of each block constituting each of the two rows of the center block row and the shoulder block row, thereby achieving excellent braking performance on ice and snow and Not only driving performance, that is, performance on ice and snow can be realized, but also water in the center block row is more efficiently discharged to the outside in the tire width direction of the tread tread edge due to the extending direction of the inclined groove. This makes it possible to realize high drainage performance, which is difficult with the conventional zigzag groove and lateral groove.

In addition, by providing a plurality of sipes in each of the blocks forming the center block row and the respective blocks forming the shoulder block row, it is possible to securely grip the icy and snowy road surface. Performance on ice and snow.

On the premise of the above configuration, by forming each block constituting each center block row into a substantially hexagonal shape, it is possible to secure high block rigidity which cannot be achieved by the conventional directional pattern. Therefore, in the form having a large number of sipes in the block, optimal block rigidity will be achieved,
By the block rigidity and the edge component of many sipes,
Excellent performance on ice and snow can be demonstrated, and by forming each block constituting the shoulder block row into a narrow and narrow shape, compared to the case of adopting a directional pattern that simply forms a hexagonal block, Since the shapes of the inclined grooves located above and below the elongated narrow block are smoothly set, more excellent drainage performance can be realized.

More preferably, in such a pneumatic tire, the width of the circumferential sub-groove is made smaller than the width of the circumferential main groove, and the amplitude of the circumferential main groove is reduced by the amplitude of the circumferential sub-groove. Smaller than. Here, the amplitude of each of the circumferential main groove and the circumferential sub groove means the amplitude of the center line of each groove in the tire width direction. By making the circumferential main groove relatively wide, excellent drainage performance can be realized, and by making the amplitude of the circumferential main groove relatively small, more excellent drainage performance can be realized. Not only that, it is possible to sufficiently secure a dominant block edge component with respect to the tire lateral force of each block located on the left and right sides of the circumferential main groove, so that it is possible to realize excellent ice and snow performance. . On the other hand, by making the circumferential sub-grooves relatively narrow, the block rigidity of each block constituting each center block row is reduced based on the mutual support between the blocks on the dry road surface and on the wet road surface. Since it is possible to secure a sufficient degree in both, in the form having a large number of sipes in the block, the optimal block rigidity will be achieved, so that the block rigidity and the edge components of the numerous sipes, Excellent performance on ice and snow, and by making the amplitude of the circumferential sub-groove relatively large, the blocks dominant in the tire longitudinal force of each block located on the left and right of the circumferential sub-groove The edge component can be increased, so that the performance on ice and snow can be secured at a higher level.

Preferably, the inclined groove has a linear shape inside the circumferential main groove in the tire width direction and a curved shape outside the circumferential main groove in the tire width direction. According to such a pneumatic tire, in the inner region in the tire width direction of each circumferential main groove, based on the shape of the inclined groove, a block edge component that is dominant with respect to the tire longitudinal force of blocks located above and below the inclined groove. It is possible to increase the performance on ice and snow to a higher level, and in the outer region in the tire width direction of each circumferential main groove, based on the shape of the inclined groove, Water can be quickly and smoothly discharged to the edge of the tread tread, thereby achieving excellent drainage performance.

[0013] Preferably, the groove width of the inclined groove is made larger in the outer region in the tire width direction of each circumferential main groove than in the tire width direction inner region of each circumferential main groove. On the outer side in the tire width direction of each circumferential main groove, it is composed of two curves each having one inflection point and projecting to the opposite side. By making the inclined groove relatively wide in the outer region in the tire width direction of each circumferential main groove, a so-called snow column shearing force generated when traveling on a snowy road can be sufficiently secured. By forming the groove from two curves each having a convex point on the opposite side having one inflection point, the block edge component and the tire longitudinal force dominant with respect to the tire lateral force of each block located above and below the inclined groove are reduced. In contrast, the dominant block edge component can be increased together,
As a result, the snow column shearing force required when the tire operates in the width direction and the circumferential direction can be exerted in a well-balanced manner, so that excellent on-ice performance can be realized as a whole.

[0014] In addition, preferably, a plurality of sipes provided in each of the blocks constituting each block row are provided substantially in parallel with the stepping side edge of the tire contact surface shape. The sipe provided almost in parallel with the stepping side edge of the tire tread surface allows each block to have enough caught on the road surface at the stepping edge of the tire, improving driving performance especially on ice and snow performance Can be done.

In the pneumatic tire having the above-described structure, more preferably, the tread center is formed narrow and linear near the constriction position of each of the blocks constituting the shoulder block row, and extends upward from below. Is provided, and each block is divided into two sub-blocks. According to such a pneumatic tire, each sub-block located on the left and right sides of the division groove is based on a hexagonal shape substantially similar to each block constituting the center block row due to the extending direction of the division groove. Since the rigidity of each sub-block can be secured at a high level, the optimal sub-block rigidity is achieved in a form having a large number of sipes in the sub-block. Excellent rigidity on ice and snow can be ensured by the block rigidity and the numerous sipe edge components.In addition, due to the split groove, each sub-block has an increased block edge component that is dominant to the tire lateral force. As a result, the vehicle can be sufficiently caught on the road surface at the time of cornering, and therefore, excellent on-ice and snow performance can be realized. In the case where the dividing groove is widened, in each of the sub-blocks, the rigidity in the tire width direction is higher than the rigidity in the tire circumferential direction, and the block rigidity is unbalanced in those directions. According to the above configuration, the rigidity of each sub-block can be set in a well-balanced manner in the tire circumferential direction and the tire width direction.

Preferably, the distance of each of the circumferential main grooves from the tread center is set to 10 to 10 of the tread tread width.
25%. Here, the distance of the circumferential main groove from the tread center means the distance from the center position of the center line of the circumferential main groove in the tire width direction to the tread center C. Also, here, the tread tread width means the tread tread width, in other words, the load width, the tire pressure, the maximum width in the width direction of the tread when the rim is under the following conditions, and the load load is The maximum load (maximum load capacity) of a single wheel in the applicable size described in the JATMA Year Book, and the tire pressure is the maximum load (maximum load capacity) of a single wheel in the applicable size described in the above standard. Refers to the corresponding air pressure, and the rim refers to the standard rim in the applicable size described in the above standard. When the distance from the tread center of each circumferential main groove is set to less than 10% of the tread tread width, the width of the center block row is too small, and there is only a concern about uneven wear of each block constituting the portion. In addition, it is not possible to realize excellent performance on ice and snow, and if it exceeds 25%, on the contrary, the width of the shoulder block row is too small, and there is a concern that uneven wear of each block constituting the relevant portion may be caused. However, according to the above configuration of the present invention, there is no concern about uneven wear of each of the blocks constituting the block rows, and therefore, excellent performance on ice and snow can be realized.

In the pneumatic tire having the above-described structure, the lowermost vertex of the sub-block defined by the circumferential main grooves, the inclined grooves, and the divided grooves, and the sub-parts defined by the inclined grooves and the divided grooves. When the straight line connecting the uppermost vertex of the tread edge of the block with the tread tread edge is in the range of 30 to 50 degrees with respect to the tire circumferential direction, both the braking performance on snow and the drainage performance are compatible. be able to. That is, if the angle between the straight line and the circumferential direction of the tire is less than 30 °, the shape of the sub-block becomes too elongated, and there is a concern that the driving performance and the abrasion resistance of the sub-block may be deteriorated. If it exceeds, the drainage performance deteriorates because the inclined groove extends substantially in the tire width direction.

The lowermost one of the corners of each block constituting the center block row is defined as:
When the angle is in the range of 70 to 110 °, since extremely low rigidity does not occur at the corners of each block, excellent block rigidity can be ensured, so that excellent snow performance and handling performance on paved roads can be obtained. Etc. can be secured.

In the case where the lowermost one of the sub-angles of the sub-blocks constituting each block of the shoulder block row is within the range of 60 to 100 °, As in the center block area, excellent block rigidity can be ensured, so that excellent snow performance and handling performance on pavement roads can be ensured. In some cases, a portion having a small protruding corner may occur, but excellent drainage performance in the shoulder block region can be realized.

According to the pneumatic tire described above, each of the blocks constituting each center block row and each of the sub-blocks constituting each block of the shoulder block row are all formed in a hexagonal shape. , While securing sufficient block rigidity over the entire tread tread, increasing the dominant block edge component with respect to the tire longitudinal force of each of the above blocks and sub-blocks, which could not be achieved by the conventional directional pattern The performance on ice and snow can be realized, and each block constituting the shoulder block row is elongated and narrow, so that it is positioned above and below the block compared to a pattern in which hexagonal blocks are simply arranged. The shape of the inclined groove can be set smoothly, which results in excellent drainage It can be realized.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded view of a tire tread showing an embodiment of the present invention in a tire front view in a mounting posture on a vehicle. When the vehicle is running forward, as shown by arrows in FIG. It rotates downward.

Here, on the tread surface 2 of the tread 1, a pair of circumferential main grooves 3 extending zigzag in the tire circumferential direction with a tread center C interposed therebetween, And a circumferential sub-groove 4 extending in a zigzag manner in the tire circumferential direction, and extending in a direction away from the tread center C from below to above in a front view of the tire in a mounting posture to the vehicle from the circumferential sub-groove 4. Then, a plurality of inclined grooves 7 that are open at the tread tread edge E are provided, and a block row is partitioned between the circumferential sub-groove 4 and each circumferential main groove 3 to form two center block rows. 5 and two circumferential main grooves 3
The shoulder block rows 6 are respectively formed on the outer side in the tire width direction, and the blocks 5 forming the respective block rows 5 and 6
a, 5b, 6a are provided with a plurality of sipes, each of the blocks 5a, 5b forming the center block row 5 is made substantially hexagonal, and each of the blocks 6a forming the shoulder block row 6 is formed as an elongated neck. Shape.

Here, the groove width of the circumferential sub-groove 4 is made smaller than the groove width of the circumferential main groove 3, and the amplitude of the circumferential main groove 3 is reduced to the amplitude of the circumferential sub-groove 4. In addition, the inclined groove 7 has a linear shape inside the circumferential main groove 3 in the tire width direction, and a curved shape outside the circumferential main groove 3 in the tire width direction. In the tire width direction outer region of each circumferential main groove 3, the circumferential groove is made larger than the tire width direction inner region of each circumferential main groove 3, and the inclined groove 7 is formed in the tire width direction of each circumferential main groove 3. On the outer side, a plurality of sipes provided on the blocks 5a, 5b, 6a constituting the respective block rows 5, 6 are constituted by two curves each having an inflection point and convex on the opposite side. It is provided almost parallel to the stepping side edge of the ground shape.

Here, the shoulder block row 6
In the vicinity of the constricted position of each of the blocks 6a, a dividing groove 8 which is narrow and linear and extends upward from the bottom toward the tread center is provided. It is divided into sub-blocks 6b and 6c, and the distance of each circumferential main groove 3 from the tread center C is set to 10 to 25% of the tread tread width T.

In addition, here, the lowermost vertex of the sub-block 6b defined by the circumferential main grooves 3, the inclined grooves 7, and the dividing grooves 8, and the inclined grooves 7 and the dividing grooves 8 are defined. Tread edge E of the sub-block 6c
The straight line l connecting the uppermost apex of the tread center with respect to the tread center is in the range of 30 to 50 °, and the lowermost of the protruding corner angles of the blocks 5a and 5b constituting the center block row 5 The protruding corner angle located is in the range of 70 to 110 °, and the lowermost protruding corner angle among the protruding corner angles of each of the sub-blocks 6 b and 6 c constituting each block 6 a of the shoulder block row 6. From 60 to 100
° range.

According to the pneumatic tire configured as described above, each block 5 forming the center block row 5
The sub-blocks 6b and 6c constituting the respective blocks 6a of the shoulder block row 6 are formed in a hexagonal shape so as to secure sufficient block rigidity over the entire tread tread surface.
a, 5b and the sub-blocks 6b, 6c, by increasing the dominant block edge components with respect to the tire longitudinal force,
A performance on ice and snow that could not be achieved by the conventional directional pattern can be realized, and each block 6a constituting the shoulder block row 6 is formed into an elongated narrow shape, so that a pattern in which hexagonal blocks are simply arranged. The shape of the inclined grooves 7 located above and below the block 6a can be set more smoothly than that of the block 6, so that excellent drainage performance can be realized.

[0027]

EXAMPLES Next, a pneumatic tire according to the present invention was prototyped, and its driving performance, braking performance, performance on ice and snow, and drainage performance were evaluated.
Example tires and conventional example tires have the configurations shown in FIGS. 1 and 2, respectively, and have the specifications shown in Table 1, respectively.

[0028]

[Table 1] * Here, the distance of the circumferential main groove 3 from the tread center C was the distance from the center position in the tire width direction of the dashed line of the circumferential main groove 3 shown in FIG.

Each test tire is filled with a predetermined air pressure,
Mounted on a four-wheeled vehicle,
Driving performance, braking performance, on-snow performance and drainage performance were each evaluated by the rider's feeling. Here, the driving performance is evaluated based on a lap time when a distance of 50 m is accelerated from a stationary state, and the braking performance is 40 km / h.
From snow, the braking performance when fully braking from is measured, the performance on ice and snow is comprehensively evaluated for driving performance, braking performance, straight running performance, and cornering performance, and the drainage performance is for passing a wet road surface at a depth of 5 mm. Evaluation was made by measuring the critical speed at which the so-called hydroplaning phenomenon occurred. In addition, all the evaluation results used the conventional tire as a control, and the larger the value, the better the result. Table 2 shows the results.

[0030]

[Table 2]

As a result of the above evaluation, it can be seen that the example tire shows superior results in both on-ice and snow performance and drainage performance as compared with the conventional tire.

[0032]

Thus, according to the present invention, it is possible to propose a technique for improving the drainage performance together with the performance on ice and snow in winter tires.

[Brief description of the drawings]

FIG. 1 is an expanded view of a tire tread showing an embodiment of the present invention in a tire front view in a mounting posture of a vehicle.

FIG. 2 is a development view of a tire tread showing a conventional embodiment in a tire front view in a mounting posture on a vehicle.

[Explanation of symbols]

Reference Signs List 1 tread 2 tread tread 3 circumferential main groove 4 circumferential sub groove 5 center block row 5a, 5b block 6 shoulder block row 6a block 6b, 6c sub block 7 inclined groove 8 split groove C tread center E tread tread edge T tread tread edge Width l The lowest vertex of the sub-block defined by each circumferential main groove, the inclined groove, and the dividing groove, and the uppermost vertex of the sub-block defined by the inclined groove and the dividing groove. Connecting straight line

Claims (10)

[Claims] A pair of circumferential main grooves extending in a tire circumferential direction in a zigzag manner, and a pair of circumferential main grooves extending in a tire width direction inside both circumferential main grooves in a tire circumferential direction. Existing circumferential sub-grooves, and a plurality of tires extending from the circumferential sub-groove in a direction away from the tread center from below to above in a front view of the tire in a mounting posture to the vehicle and opening to the tread tread edge. An inclined groove is provided, and a block row is partitioned between the circumferential sub-groove and each circumferential main groove to form two rows of center block rows. In the pneumatic tire in which each shoulder block row is formed and each of the blocks constituting each block row is provided with a plurality of sipes, each block constituting each of the center block rows is substantially hexagonal. With the Jo, pneumatic tire according to the blocks constituting the shoulder block row, as an elongated constricted shape. 2. The method according to claim 1, wherein the width of the circumferential sub-groove is made smaller than the width of the circumferential main groove, and the amplitude of the circumferential main groove is made smaller than the amplitude of the circumferential sub-groove. Claim 1
A pneumatic tire according to claim 1. 3. The pneumatic tire according to claim 1, wherein the inclined groove has a linear shape inside the circumferential main groove in the tire width direction, and has a curved shape outside the circumferential main groove in the tire width direction. 4. The groove width of the inclined groove is made larger in the outer region in the tire width direction of each circumferential main groove than in the tire width direction inner region of each circumferential main groove. An outer side in the tire width direction of the direction main groove is constituted by two curves each having one inflection point and convex on opposite sides.
A pneumatic tire according to any one of claims 1 to 3. 5. The sipe according to claim 1, wherein a plurality of sipes provided in each of the blocks constituting each block row are provided substantially in parallel with a stepping side edge of a tire contact surface shape. Pneumatic tire. 6. A narrow, linear shape near the constriction position of each block constituting the shoulder block row,
The pneumatic tire according to any one of claims 1 to 5, wherein a dividing groove extending from a lower portion to an upper portion in a direction approaching the tread center is provided, and each of the blocks is divided into two sub-blocks. 7. The pneumatic tire according to claim 1, wherein a distance between each of the circumferential main grooves from a tread center is 10 to 25% of a tread tread width. 8. A tread edge of a tread of a lowermost vertex of a sub-block defined by the circumferential main grooves, the inclined grooves, and the divided grooves, and a sub-block defined by the inclined grooves and the divided grooves. The pneumatic tire according to claim 6 or 7, wherein a straight line connecting the uppermost apex in (3) is in a range of 30 to 50 ° with respect to the tire circumferential direction. 9. The lowermost one of the corners of each block constituting the center block row is defined as:
The pneumatic tire according to any one of claims 1 to 8, which has a range of 70 to 110 °. 10. The lowermost one of the sub corners of each of the sub-blocks constituting each block of the shoulder block row is in the range of 60 to 100 °. 10. The pneumatic tire according to any one of 9 above.