JP6101053B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire.

  Conventionally, as a pneumatic tire with improved performance on ice, the present applicant has a block group in which a plurality of independent blocks are closely packed together, and the number density of the blocks in the reference area is within a predetermined range. A tire having a tread pattern has been proposed (see, for example, Patent Document 1). According to this tire, it is possible to dramatically improve the performance on ice by ensuring excellent ground contact and edge effect and efficiently removing the water film by the block.

International Publication 2010/032606 Pamphlet

However, the inventors have studied the above tires. However, in the above tires, since the small blocks are densely arranged at a high number density, the rigidity of the blocks alone is low, and particularly the tire rolling. It has been newly found that there is a problem that a large deformation occurs at each input on the kicking side of the block where a large contact pressure is applied during the movement, and there is a possibility that a crack may occur on the wall surface of the block. It was also found that when the block has sipes extending in the tread width direction, the rigidity of the block land portions at both ends in the tread circumferential direction defined by the sipes is lowered, and the probability of occurrence of cracks is increased.
Further, it has been found that such a problem is likely to occur in a block disposed at the center portion in the width direction of the tread surface where the contact length becomes long and the contact pressure becomes high particularly during acceleration / deceleration.

  An object of the present invention is to solve the above-described problem, and to provide a pneumatic tire capable of suppressing the occurrence of cracks while ensuring on-ice performance.

The gist configuration of the present invention is as follows.
The pneumatic tire of the present invention, the tread surface is partitioned by the groove, there is an area of each of the tread in the range of 100 to 200 mm ^2, a plurality of blocks having a tread shape or polygonal pentagonal in the tread circumferential direction A plurality of block rows arranged in the tread width direction are provided,
The blocks are densely arranged in a staggered manner in which the positional relationship between the blocks between adjacent block rows is different from each other in the tread circumferential direction,
When a tread width direction region corresponding to 80% of the tread contact width TW centered on the tire equator plane is a center portion, the block row is provided in at least a part of the center portion, and at least in the center portion, the tread In the groove between the blocks adjacent in the circumferential direction, a connecting portion for connecting the blocks in the tread circumferential direction is provided ,
The length of the groove in the tread width direction of the portion provided with the connecting portion is shorter than the length of the groove in the longitudinal direction of the portion between the blocks adjacent to each other in a staggered manner between the adjacent block rows. And
Thereby, while ensuring on-ice performance, it is possible to increase the rigidity of the block and suppress the occurrence of cracks.
Here, the “tread surface” means that the pneumatic tire is attached to an applicable rim, filled with a specified internal pressure, loaded with a maximum load, and in contact with the road surface in a reference state. It means the outer peripheral surface over the entire circumference. The “tread grounding width TW” refers to the maximum width in the tread width direction of the grounding surface in the reference state.
Here, the “applicable rim” is a rim in which an industrial standard effective for the region where the tire is produced and used is determined for each tire. If it is JATMA (Japan Automobile Tire Association), the standard rim, TRA ( “THE TIRE and RIM ASSOCIATION INC.” Is “Design Rim”, and ETRTO (European Tire and Rim Technical Organization) is “Measuring RIM”. “Maximum load load” refers to the maximum load of a tire defined by the above standards such as JATMA according to the tire size, and “specified internal pressure” refers to the air pressure (maximum air pressure) corresponding to the maximum load load. Point to.

In the tire according to the present invention, it is preferable that the block has at least one sipe extending in the tread width direction.
This is because an edge component in the tread width direction (an edge component with respect to the tread circumferential direction) can be secured, and the on-ice performance of the tire can be further improved.

Furthermore, in the pneumatic tire of the present invention, when the height of the block is H (mm) and the height of the connecting portion is h (mm), the ratio h / H is 10% or more and 70. % Or less is preferable.
This is to prevent the above-mentioned connecting portion from coming into contact with the ground until a certain amount of wear during the progress of wear of the tire while sufficiently exerting the above-described crack suppressing effect.
Here, “the height H (mm) of the block” and “the height h (mm) of the connecting portion” mean the height from the groove bottom of the groove adjacent to the connecting portion, as shown in FIG. For the former, if the height of the block is not constant, the maximum height of the block shall be said. For the latter, if the height of the connecting portion is not constant, the maximum height of the connecting portion. It shall be said.

In the pneumatic tire of the present invention, it is preferable that the inclination angle θ (°) of the side wall on both sides in the tread width direction of the connecting portion with respect to the tire radial direction is 0 ° or more and 5 ° or less.
This is because drainage performance and snow drainage performance can be secured while securing the rigidity of the block.
Here, “inclination angle θ (°)” means an angle when a tire is mounted on an applicable rim, filled with a specified internal pressure, and in a no-load state, and when the inclination angle is not constant, The minimum inclination angle of the side wall shall be said.
In the pneumatic tire of the present invention, it is preferable that the width direction groove 3 extends from the tread ground end TCE inward in the tread width direction and extends to a region defined by the tread ground end TCE and the circumferential groove 2. This is because a ground contact area can be ensured and turbulence caused by the communication of these grooves can be suppressed.
Furthermore, in the pneumatic tire of the present invention, the tread shape is a pentagonal or more polygonal block is arranged such that two sides on both ends of the tread circumferential direction extend in the tread width direction,
Of the two sides, the length of the side of the block when the tire is rotated is a (mm), and the length of the block in the tread circumferential direction is b (mm). When doing so, the ratio a / b is preferably greater than 0.5. This is because the crack-proof performance can be improved by increasing the rigidity on the kicking side of the block.
Further, it is more preferable that the ratio c / b is more than 0.5, where c (mm) is the length of the side of the block that is depressed when the tire rotates. This is because the rigidity on the stepping side of the block can be increased and the crack resistance can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which can suppress generation | occurrence | production of a crack can be provided, ensuring the performance on ice.

It is a partial development figure showing a tread pattern of a tire concerning one embodiment of the present invention. It is a figure shown about the height H of a block, and the height h of a connection part. It is a figure shown about inclination-angle (theta) of the tread width direction both side wall of a connection part. It is a figure for demonstrating the tread shape of a block. It is a partial development figure showing the tread pattern of the tire concerning a comparative example. It is a partial development view showing a tread pattern of a tire concerning an example of an invention.

  Hereinafter, a pneumatic tire (hereinafter, also referred to as a tire) according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a partial development view showing a tread pattern of a tire according to an embodiment of the present invention. In addition, about the internal structure of a tire, since it is the same as that of the past, description is abbreviate | omitted.

  As shown in FIG. 1, the tire includes two circumferential main grooves 2 extending in the tread circumferential direction on the tread tread surface 1 in the illustrated example, and a widthwise groove 3 extending inward in the tread width direction TE from the tread end TE. And a plurality of narrow grooves 4 extending in a zigzag shape in the tread circumferential direction. As shown in FIG. 1, these grooves 2, 3, 4 divide and form a plurality of blocks 5 having an octagonal planar shape (except for those adjacent to the circumferential main groove 2) in the illustrated example. Has been. As shown in FIG. 1, a plurality of block rows in which a plurality of blocks 5 are arranged in the tread circumferential direction are provided in the tread width direction. In the illustrated example, the blocks 5 between the block rows adjacent in the tread width direction have a phase difference in the tread circumferential direction (in the illustrated example, a phase difference that is half the tread circumferential length of the block is provided. ) It is densely arranged in a staggered pattern. Further, in the illustrated example, each block 5 is provided with two sipes 6 extending substantially in the tread width direction. In the present embodiment, the planar shape of the block is an octagonal shape, but it may be a polygonal shape that is a pentagon or more, and may be other polygonal shapes such as a hexagonal shape.

Here, the area of the tread of the block 5 is in the range of 100 to 200 mm ² .

Further, when a region corresponding to 80% of the tread contact width TW centered on the tire equatorial plane CL is defined as the center portion C, as shown in FIG. 1, in this tire, at least a partial region of the center portion C is used. The above-described block row is arranged.
In the illustrated example, in the center portion C, except between the blocks 5 in the block row adjacent to the circumferential main groove 2 on both sides in the tread width direction and between the blocks 5 partitioned by the width direction groove 3. A connecting portion 7 is provided between all the blocks 5 adjacent in the tread circumferential direction to connect the blocks 5 in the tread circumferential direction.
Thus, in the tire according to the present invention, at least at the center portion C, at least a part of the blocks 5 adjacent to each other in the tread circumferential direction is provided with a connecting portion 7 that couples the blocks 5 in the tread circumferential direction. It is important.
Hereinafter, the effect of the tire concerning this embodiment is explained.

In the tire according to the present embodiment, a configuration in which the blocks 5 are densely arranged while ensuring a sufficient groove area on the tread surface is adopted, so that the total edge length and edge direction of each block 5 (different directions) The number of edges facing the surface can be increased, and an excellent edge effect can be exhibited. Moreover, since the area of the tread surface of each block 5, ie, the ground contact area, is reduced, the ground contact performance of each block can be improved, and high performance on ice can be exhibited. In addition, since the distance from the central area of the block 5 to the peripheral edge of the block 5 can be reduced by reducing the ground contact area of each block 5, the effect of removing the water film by the block 5 can be improved. Therefore, according to the tire of the present embodiment, it is possible to dramatically improve the performance on ice by ensuring excellent grounding performance and edge effect and efficiently removing the water film by the block 5. . In addition, if the area of the tread surface of the block 5 in the contact surface is in the range of 100 to 200 mm ² , both the block rigidity and the edge effect can be achieved at a higher level, and the performance on ice more effectively. Can be improved.

Furthermore, according to the tire of the present embodiment, in the center portion C, the connecting portions 7 that connect the blocks 5 in the tread circumferential direction are provided between the blocks 5 adjacent to each other in the tread circumferential direction. The rigidity of the end portion in the tread circumferential direction of the block thus increased can suppress the deformation of the block and suppress the occurrence of cracks in the block. As in the present embodiment, the connecting portion 7 is provided between the block 5 in the block row adjacent to the circumferential main groove 2 on both sides in the tread width direction and the block 5 partitioned by the width direction groove 3. It can be set as the structure which does not provide. Thereby, drainage performance and snow drainage performance can be ensured, and grounding performance can also be secured. On the other hand, a connection part can also be provided between all the blocks 5 adjacent to the tread circumferential direction.
In the present invention, as shown in FIG. 1, the block 5 preferably has sipes 6 extending in the tread width direction, and the block 5 preferably has two or three sipes 6 extending in the tread width direction. . This is because the edge component in the tread width direction can be secured by this, and the on-ice performance of the tire can be secured. On the other hand, when such a sipe is provided, the rigidity of the end portion in the tread circumferential direction of the block 5 is lowered, but according to the present invention, the end portion in the tread circumferential direction of the block is connected by the connecting portion 7. This is because the rigidity is increased, and the occurrence of cracks can be effectively suppressed even in such a case.
Note that “sipe” is a thin notch that is cut from the surface of the block to the inside, and that can be closed when grounded. In order to obtain the above effect, the width of the sipe 6 is It is preferable to be 0.2 to 1.0 mm, and the depth of the sipe 6 is preferably 5.5 to 9.0 mm.
Further, in this embodiment, the sipe communicates with the circumferential main groove 2 and the narrow groove 4, but from the viewpoint of improving the crack resistance by maintaining the rigidity of the block, the sipe is connected to the block 5. 6, the sipe 6 can extend so as to remain in the land portion of the block 5 without communicating with the circumferential main groove 2, the width direction groove 3, and the narrow groove 4.

In the present invention, as shown in FIG. 2, the height of the block 5 (equal to the groove depth of the narrow groove 4) is H (mm), and the height of the connecting portion 7 is h (mm). , The ratio h / H is preferably 10% or more and 70% or less. This is because by setting the ratio h / H to 10% or more, the rigidity of the circumferential end of the block can be further increased. In particular, when a so-called cap-and-base structure is adopted for the tread rubber, cracks are likely to occur near the interface between the cap rubber and the base rubber, which is usually located near the groove bottom. The rigidity in the vicinity of the interface can be reliably increased. On the other hand, by setting the ratio h / H to 70% or less, even if the height of the block is reduced due to wear, the connecting portion can be prevented from being grounded until a constant wear.
More specifically, the height H (mm) of the block is preferably 5.0 to 9.0 mm, and the height h (mm) of the connecting portion is 4.0 to 6.0 mm. Is preferred.

  In the present invention, as shown in FIG. 3, the inclination angle θ (°) of the side wall 7a on both sides in the tread width direction of the connecting portion 7 with respect to the tire radial direction is 0 ° or more and 5 ° or less. preferable. By setting the inclination angle θ to 0 ° or more, block rigidity can be secured and cracks can be suppressed. On the other hand, by setting the inclination angle θ to 5 ° or less, drainage performance and snow drainage performance are ensured. This is because the grounding property can be secured.

  Further, according to the tire of the present embodiment, since the blocks 5 are densely arranged in a zigzag shape in the tread circumferential direction, each edge is caused to act sequentially while forming more blocks 5 when the tire rolls. More effective edge effect. In addition, since the ground contact timing to the road surface can be shifted between the blocks 5 adjacent in the tread width direction, pattern noise can also be reduced.

By the way, in this invention, it is preferable that the negative rate N of the tread surface is 5% to 50%. This is because when the negative rate N of the tread surface is less than 5%, the groove area is too small and the drainage performance becomes insufficient. On the other hand, when it exceeds 50%, the ground contact area becomes too small and steering stability is lowered. It is because there is a possibility of doing. Further, when the ground contact area of each block 5 exceeds 200 (mm ² ), it is difficult to achieve a high edge effect. On the other hand, if the ground contact area of each block 5 is less than 100 (mm ² ), the ground contact area of block 3 Is too small to achieve the required block rigidity.
The “negative ratio N of the tread surface” means the ratio of the groove area to the ground contact area in the reference state.

Moreover, in this invention, it is preferable to provide the circumferential direction main groove 2 and the width direction groove | channel 3 as shown in FIG. This is because drainage can be secured.
Here, the circumferential groove 2 refers to a groove extending substantially in the tread circumferential direction and having a groove width of 2.0 mm or more, and the shape is not particularly limited, and includes a linear shape, a zigzag shape, a bent shape, and the like. . Moreover, it is preferable that the groove width of the circumferential groove | channel 2 shall be 3.5-15.0 mm. This is because the ground contact area can be ensured by ensuring that the negative rate does not become too large while ensuring drainage. Moreover, it is preferable that the depth of the circumferential groove | channel 2 shall be 8.0-10.5 mm. This is to ensure the rigidity of the block while ensuring drainage.
Moreover, the width direction groove | channel 3 shall extend in a tread width direction substantially, and shall mean the groove | channel whose groove width is 1.5 mm or more. It is preferable that the width direction groove | channel 3 inclines and extends at an angle of 0-60 degrees with respect to the tread width direction. Furthermore, it is preferable that the groove width of the width direction groove | channel 3 shall be 2-15 mm. This is because the ground contact area can be ensured by ensuring that the negative rate does not become too large while ensuring drainage. Moreover, it is preferable that the depth of the width direction groove | channel 3 shall be 8.0-10.5 mm. This is to ensure the rigidity of the block while ensuring drainage.
In the present invention, as shown in FIG. 1, the width direction groove 3 extends from the tread ground end TCE inward in the tread width direction, and is defined by the tread ground end TCE and the circumferential groove 2. It is preferable to extend to. In other words, it is preferable that the circumferential main groove 2 having an opening width to the tread surface 1 of 3 mm or more and the width direction groove 3 having an opening width to the tread surface 1 of 2 mm or more do not directly communicate with each other.
This is because a ground contact area can be ensured and turbulence caused by the communication of these grooves can be suppressed.
Furthermore, in this case, as shown in FIG. 1, it is more preferable that the circumferential main groove 2 and the width direction groove 3 communicate with each other through the narrow groove 4.
This is because the snow column shear force can be effectively exhibited.

  Furthermore, as shown in FIG. 1, when the narrow groove 4 is provided, it is preferable that the narrow groove 4 has a width that allows the blocks to be individually movable without being constrained by each other. Specifically, the thickness is preferably 0.7 to 3 mm.

Here, in the present invention, as shown in FIG. 4, the shape of the block is such that the length of the four sides of the oblique side e1 (side inclined with respect to the tread circumferential direction and the tread width direction) is the other four. It is preferable that the octagonal shape is longer than the length of the side e2 (side extending along the tread circumferential direction or the tread width direction). This is because, for example, a length component in the tread circumferential direction can be ensured compared to a regular octagon, and the occurrence of cracks in the block can be further suppressed.
Further, in the pneumatic tire of the present invention, the polygonal block 5 having a tread shape of a pentagon or more is arranged such that two sides on both ends of the tread circumferential direction extend in the tread width direction, and the two sides Among them, when the length of the side of the block 5 on the kicking side during rotation of the tire is a (mm) and the length in the tread width direction at the tread circumferential center position is b (mm), the ratio a / B is preferably greater than 0.5. It is possible to secure the length in the width direction of the edge of the block's kick-out side, and it is possible to improve the crack resistance performance by increasing the rigidity of the block's kick-out side end, especially when the contact pressure is large is there.
Further, it is more preferable that the ratio c / b is more than 0.5, where c (mm) is the length of the side of the block 5 at the time of depression of the two sides when the tire rotates. This is because the rigidity on the stepping side of the block can be increased and the crack resistance can be improved.

In order to confirm the effects of the present invention, tires according to Invention Examples 1 to 7 and tires according to Comparative Examples were made as trials, and the following evaluations on ice performance and crack resistance were performed.
The specifications and evaluation results of each tire are shown in Table 1 below.
In Table 1, the “octagonal shape” of the block means an octagonal shape in which the four sides of the oblique side are longer than the other four sides, as shown in FIGS. 1 and 4.

<Performance on ice>
Each of the tires having a tire size of 195 / 65R15 was assembled on a rim having a rim size of 15 × 6.0 J, an internal pressure was set to 240 kPa, and evaluation was performed by performing a braking test on an icy road surface.
In Table 1, the evaluation result is shown as an index when the evaluation result of the tire according to the comparative example is set to 100, and a larger numerical value indicates better performance on ice.
<Crack resistance>
The above tires having a tire size of 195 / 65R15 were assembled on a rim having a rim size of 15 × 6.0 J, the internal pressure was set to 240 kPa, and a constant input was applied to travel a certain distance to evaluate the occurrence of cracks.
In Table 1, the evaluation result is shown as an index when the evaluation result of the tire according to the comparative example is set to 100, and a larger numerical value indicates better crack resistance performance.

As shown in Table 1, it can be seen that the tires according to Invention Examples 1 to 7 can improve the crack resistance performance while securing the performance on ice as compared with the comparative example.
In particular, a comparison between Invention Example 1 and Invention Example 2 shows that the present invention can effectively suppress the occurrence of cracks even when the block has sipes. Moreover, it turns out that the tire concerning invention example 1 in which a block has a sipe has improved on-ice performance compared with the invention example 2 in which a block does not have a sipe.
Moreover, it can be seen from comparison between Invention Example 1 and Invention Examples 3 and 4 that Invention Example 1 and 4 in which the ratio h / H is optimized have improved crack resistance compared to Invention Example 3.
Furthermore, it can be seen from comparison between Invention Example 1 and Invention Examples 5 to 7 that Invention Examples 1, 5, and 6 in which the inclination angle θ is optimized have better crack resistance performance than Invention Example 7.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which can suppress generation | occurrence | production of a crack can be provided, ensuring the performance on ice.

1 tread surface 2 circumferential main groove 3 width direction groove 4 narrow groove 5 block 6 sipe 7 connecting portion CL tire equatorial surface TE tread edge

Claims (4)

A block row formed by arranging a plurality of blocks having a polygonal tread shape of a pentagon or more in the tread circumferential direction, which is partitioned by grooves on the tread tread, the area of each tread being in the range of 100 to 200 mm ² , Provide multiple rows in the tread width direction,
The blocks are densely arranged in a staggered manner in which the positional relationship between the blocks between adjacent block rows is different from each other in the tread circumferential direction,
When a tread width direction region corresponding to 80% of the tread contact width TW centered on the tire equator plane is a center portion, the block row is provided in at least a part of the center portion, and at least in the center portion, the tread In the groove between the blocks adjacent in the circumferential direction, a connecting portion for connecting the blocks in the tread circumferential direction is provided ,
The length of the groove in the tread width direction of the portion provided with the connecting portion is shorter than the length of the groove in the longitudinal direction of the portion between the blocks adjacent to each other in a staggered manner between the adjacent block rows. And pneumatic tires.   The pneumatic tire according to claim 1, wherein the block has at least one sipe extending in a tread width direction.   The ratio h / H is 10% or more and 70% or less when the height of the block is H (mm) and the height of the connecting portion is h (mm). Pneumatic tire.   The pneumatic tire according to any one of claims 1 to 3, wherein an inclination angle θ (°) with respect to a tire radial direction of side walls on both sides in the tread width direction of the connecting portion is 0 ° or more and 5 ° or less.

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