JP5001623B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that suppresses the occurrence of a phenomenon called stone biting that ensures traction performance and drainage performance and prevents stones from being caught in tire grooves.

  In order to obtain desired performance such as drainage performance, traction performance, braking performance, etc., the tread is engraved with a main groove extending in the tire circumferential direction and a lateral groove extending in the tire width direction. If stones are caught in the groove and cannot be removed, the stone may gradually enter the groove bottom and damage the groove bottom. Furthermore, when stones enter, the belt layer and the auxiliary belt layer may be damaged, causing failure. In particular, the main groove has such a tendency that the deformation of the groove due to tire rotation is small. In order to prevent such stone biting, a pneumatic tire is known in which a protrusion (called a stone ejector) is provided at the center of the bottom of the main groove so that stones do not enter (Patent Document 1).

JP 2002-293110 A

  However, if a protrusion having a height that can sufficiently prevent stone biting is provided at the center of the bottom of the main groove, the drainage of the main groove is greatly impaired. Further, since the protrusion is easily deformed when the stone enters, a crack is likely to occur at the connecting portion between the protrusion and the groove bottom. Therefore, it has been difficult to achieve both drainage performance and prevention of stone biting.

  Accordingly, an object of the present invention is to prevent stone biting while maintaining drainage performance.

In order to solve the above problems, the present invention provides a pneumatic tire in which three or more main grooves extending in the tire circumferential direction are carved and ribs are formed by the main grooves. Linearly extending in the direction, the groove bottom of the main groove extends zigzag in the tire circumferential direction, the side wall of the main groove includes a recess and a protrusion, and the recess in the side wall of at least one of the main grooves A protrusion connected to the groove bottom and the side wall of the main groove; a sipe extending from the recess toward the inside of the rib in the tire width direction; a distance W1 from the protrusion to the opposite side wall at the groove bottom; the groove Of the spacing W2 between the adjacent projections at the bottom, a large value is 2.0 times or less of a small value, and a small value of W1 and W2 is the groove width at the groove bottom when the projection is removed. is 50% to 70% of W It is a pneumatic tire, wherein the door.

In the pneumatic tire in which three or more main grooves extending in the tire circumferential direction are formed and ribs are formed by the main grooves, the ridgeline of the main groove at the time of a new article extends linearly in the tire circumferential direction. The groove bottom of the main groove extends zigzag in the tire circumferential direction, the side wall of the main groove includes a recess and a protrusion, and the groove bottom and the side wall of the main groove are provided in the recess of the side wall of at least one of the main grooves. And a notch extending inward in the tire width direction of the rib from the recess, a distance W1 from the protrusion to the opposite side wall at the groove bottom, and the adjacent protrusion at the groove bottom. The larger value of the interval W2 is 2.0 times or less of the smaller value, and the smaller value of W1 and W2 is 50% to 70% of the groove width W at the groove bottom when the protrusion is removed. pneumatic, characterized in that it is It is hate.

  When new, the main groove extends linearly in the tire circumferential direction, so that the occurrence of uneven wear of the ribs can be suppressed. Since the groove bottom of the main groove extends in a zigzag shape in the tire circumferential direction, the main groove extends in a zigzag shape as wear progresses, so that the traction performance and braking performance of the tire are improved. Further, when wear progresses and protrusions appear on the tread surface, the protrusions improve traction performance and braking performance.

  Even if a stone is caught in the main groove, the protrusion can prevent the stone from entering in the groove bottom direction and can prevent the stone from being bitten. Further, since the protrusions are not continuous and are arranged at intervals, the drainage of the main groove is not impaired. Further, since the protrusion is connected to the side wall, it does not easily deform even when a stone enters, so that a crack does not occur at the connecting portion between the groove bottom and the protrusion.

  The concave portion on the side wall of the main groove is higher in rigidity than the convex portion, and further provided with a projection, so that the rigidity is further increased. Therefore, by cutting a sipe or notch extending from the concave portion toward the inside of the rib in the tire width direction, the rigidity of the concave portion of the side wall is lowered, the difference in rigidity from the convex portion of the side wall is reduced, and uneven wear is suppressed.

Further, from the viewpoint of securing the drainability of the main groove, the distance W1 from the protrusion to the opposite side wall and the interval W2 between the adjacent protrusions are set within a predetermined range.
The present invention is a pneumatic tire provided with the projections on both side walls of the main groove.

  By providing the protrusions on both side walls, the stone biting prevention effect and the traction performance and braking performance during wear progress are improved.

  The present invention is a pneumatic tire in which a height H from the groove bottom of the protrusion is 10% to 40% of a depth D of the main groove.

  If the height H from the groove bottom of the protrusion is less than 10% of the depth D of the main groove, the stone biting suppression effect may be low, and if it exceeds 40%, the drainage performance of the main groove may be impaired.

  The present invention is a pneumatic tire in which a circumferential length L2 on the side farther from the side wall of the protrusion is shorter than a circumferential length L1 on the side closer to the side wall.

  From the viewpoint of securing the drainability of the main groove, it is preferable that the circumferential length L2 on the side far from the side wall of the protrusion is shorter than the circumferential length L1 on the side near the side wall.

  Hereinafter, an embodiment of a pneumatic tire according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a tread pattern when new. In the figure, a rib 2 is formed by a main groove 1 extending in the tire circumferential direction R. The ridgeline 11 of the main groove 1 at the time of a new article extends linearly in the tire circumferential direction R. On the other hand, the groove bottom 12 of the main groove 1 extends in a zigzag shape in the tire circumferential direction R. As a result, the occurrence of uneven wear of the ribs 2 can be suppressed from the new article to the early stage of wear. Thereafter, since the main groove 1 extends in a zigzag shape, the traction performance and braking performance of the tire are improved.

  FIG. 2 is a perspective view showing a part of the main groove. The side wall 13 of the main groove 1 is provided with concave portions 14 and convex portions 15 alternately. The recess 14 includes a protrusion 3 connected to the groove bottom 12 and the side wall 13 of the main groove 1. Therefore, even if a stone is caught in the main groove 1, the protrusion 3 can prevent the stone from entering in the groove bottom direction and can prevent the stone from biting. Moreover, since the protrusions 3 are not continuous but are arranged at intervals, the drainage performance of the main groove 1 is not impaired.

  Since the protrusion 3 is connected to the side wall 13, no crack is generated at the connecting portion between the groove bottom 12 and the protrusion 3. When the wear progresses and the protrusion 3 appears on the tread surface, the protrusion 3 improves the traction performance and braking performance. The protrusion 3 may be provided on at least one side wall 13, but may be provided on both side walls 13.

  A sipe 4 is engraved from the concave portion 14 of the side wall 13 so as to extend inward in the tire width direction of the rib 2. The sipe 4 reduces the rigidity of the concave portion 14 of the side wall 13 whose rigidity is increased by the protrusion 3. As a result, the difference in rigidity between the concave portion 14 and the convex portion 15 of the side wall 13 is reduced, and uneven wear can be suppressed. In addition, it is preferable that the depth of the sipe 4 is a depth until it reaches the protrusion 3, and the length of the sipe 4 is preferably 5% to 15% of the width of the rib 2. If the length of the sipe 4 is too short, the effect of reducing the difference in rigidity between the concave portion 14 and the convex portion 15 is small. If the length of the sipe 4 is too long, the rigidity of the concave portion 14 becomes too small.

  FIG. 3 is a schematic view showing a tread pattern when new, according to another embodiment, and FIG. 4 is a perspective view showing a part of the main groove. The operational effects of the projection 3 are the same as in FIGS. 1 and 2, but a notch 5 is formed extending from the concave portion 14 of the side wall 13 to the inside of the rib 2 in the tire width direction instead of the sipe. Similar to the sipe 4, the notch 5 reduces the rigidity of the concave portion 14 of the side wall 13 whose rigidity is increased by the protrusion 3. As a result, the difference in rigidity between the concave portion 14 and the convex portion 15 of the side wall 13 is reduced, and uneven wear can be suppressed. Note that the depth of the notch 5 is preferably the depth to reach the protrusion 3, and the length of the notch 5 is preferably 5% to 15% of the width of the rib 2 and opens to the side wall 13 of the notch 5. The width is preferably 2 mm to 8 mm. If the length of the notch 5 is too short or the opening width is too narrow, the effect of reducing the rigidity difference between the concave portion 14 and the convex portion 15 is small. If the length of the notch 5 is too long or the opening width is too wide, the rigidity of the recess 14 becomes too small.

  FIG. 5 is a cross-sectional view taken along line AA in FIGS. 1 and 3. The height H of the protrusion 3 from the groove bottom 12 is preferably 10% to 40% of the depth D of the main groove 1. If the height H is less than 10% of the depth D, the stone biting suppression effect may be low, and if it exceeds 40%, the drainage performance of the main groove 1 may be impaired.

6 is an enlarged view showing the groove bottom of the main groove in FIG. 1, FIG. 7 is an enlarged view showing the groove bottom of the main groove in FIG. 3, and the groove bottom 12 is hatched. W1 is the distance from the protrusion 3 to the opposite side wall 13 at the groove bottom 12. W2 is an interval between adjacent protrusions 3 in the groove bottom 12. In order to ensure sufficient drainage performance, it is necessary that there is no sudden change in the width of the groove bottom 12. Therefore, the larger value needs to be 2.0 times or less than the smaller value of W1 and W2. 6 and 7, W2 is larger than W1, but depending on the size of the protrusion 3, W1 becomes larger or W2 becomes larger.

Further, if the groove width at the groove bottom 12 when excluding the projections 3 is W, a small value of the W1 and W2 is set to 50% to 70% of W. If it is less than 50%, the drainage performance may be impaired, and if it exceeds 70%, the protrusion 3 is small, and stone biting may not be prevented. Furthermore, from the viewpoint of ensuring drainage, if the circumferential length on the side farther from the side wall 13 of the protrusion 3 is L2, and the circumferential length L1 on the side closer to the side wall 13, L1 is preferably shorter than L2.

  The pneumatic tire according to the present invention was prototyped as an example, the pneumatic tire according to the present invention was prototyped as an example, and the evaluation was performed by mounting on a truck with a load capacity of 10 tons (2-D axle configuration). . In addition, the tread pattern of Example 1 is the pattern shown in FIG. 1, and the tread pattern of Example 2 is the pattern shown in FIG. The depth D of the main groove 1 is 14.5 mm, the height H of the protrusion 3 is 3 mm, W, W1, and W2 in FIGS. 6 and 7 are 7 mm, 4.5 mm, 6.5 mm, and L1 and L2 are 23 mm, respectively. It was 17 mm. The width of the rib 2 was 38 mm, the length of the sipe 4 was 2.5 mm, the length of the notch 5 was 4 mm, and the opening width at the side wall 13 was 5.5 mm.

  The tires of Conventional Examples 1 and 2 have the same pattern as Examples 1 and 2, respectively, but do not have protrusions. However, Conventional Example 1 includes the same sipe as Example 1, and Conventional Example 2 includes the same notch as Example 2. The tire of Conventional Example 3 has the same pattern as the Example, but the groove bottom also extends in a straight line, and protrusions having a width of 3 mm, a height of 3 mm, and a circumferential length of 6 mm are arranged at an interval of 2 mm at the center of the groove bottom. Tire. The tire size was 11R22.5, the mounting rim size was 22.5 × 7.50, and the set internal pressure was 700 kPa.

According to Table 1, in the tire of the present invention, it was possible to prevent the occurrence of stone biting while maintaining the drainage performance, and to improve the traction performance during wear. In addition, the evaluation method of each item shown in Table 1 is as follows. Each is an index with the conventional example 1 as 100, and the larger the value, the better the performance.
(1) Drainage performance The speed is gradually increased from 50km / h on a wet road surface with a depth of 3mm. When hydroplaning occurs (when a change in steering response is felt) The average value by the driver.
(2) Traction performance This is the braking distance from 60 km / h on a dry road surface. A short braking distance indicates good traction performance.
(3) Stone biting prevention performance After traveling 10,000 km on a general road, the number of stones caught in the main groove was measured.

It is the schematic which shows the tread pattern at the time of the new article of the pneumatic tire which concerns on this invention. FIG. 2 is a perspective view showing a part of a main groove in FIG. 1. It is the schematic which shows the tread pattern at the time of the new article of the pneumatic tire which concerns on this invention. FIG. 4 is a perspective view showing a part of a main groove in FIG. 3. It is the sectional view on the AA line of FIG.1 and FIG.3. It is an enlarged view which shows the groove bottom of the main groove of FIG. It is an enlarged view which shows the groove bottom of the main groove of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main groove 2 Rib 3 Protrusion 4 Sipe 5 Notch 11 Main groove ridgeline 12 Main groove groove bottom 13 Main groove side wall 14 Main groove side wall concave part 15 Main groove side wall convex part

Claims (5)

In a pneumatic tire in which three or more main grooves extending in the tire circumferential direction are cut and ribs are formed by the main grooves,
The ridgeline of the main groove at the time of a new article extends linearly in the tire circumferential direction, the groove bottom of the main groove extends zigzag in the tire circumferential direction, the side wall of the main groove includes a recess and a projection, and at least one of them A recess connected to the groove bottom and the side wall of the main groove, and a sipe extending from the recess to the inside of the rib in the tire width direction.
Of the distance W1 from the protrusion to the opposite side wall at the groove bottom, and the interval W2 between the adjacent protrusions at the groove bottom, the larger value is 2.0 times the smaller value,
A pneumatic tire characterized in that a small value of W1 and W2 is 50% to 70% of a groove width W at the groove bottom when the protrusion is removed . In a pneumatic tire in which three or more main grooves extending in the tire circumferential direction are cut and ribs are formed by the main grooves,
The ridgeline of the main groove at the time of a new article extends linearly in the tire circumferential direction, the groove bottom of the main groove extends zigzag in the tire circumferential direction, the side wall of the main groove includes a recess and a projection, and at least one of them A recess connected to the groove bottom and side wall of the main groove, and a notch extending inward in the tire width direction of the rib from the recess.
Of the distance W1 from the protrusion to the opposite side wall at the groove bottom, and the interval W2 between the adjacent protrusions at the groove bottom, the larger value is 2.0 times the smaller value,
A pneumatic tire characterized in that a small value of W1 and W2 is 50% to 70% of a groove width W at the groove bottom when the protrusion is removed . The pneumatic tire according to claim 1, wherein the protrusions are provided on both side walls of the main groove. The pneumatic tire according to any one of claims 1 to 3, wherein a height H of the protrusion from the groove bottom is 10% to 40% of a depth D of the main groove. Wherein the circumferential length of the side far from the side walls L2 of the protrusions, the pneumatic tire according to either side of the circumferential length L1 shorter than the claims 1 to 4 close to the side wall.

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