JP5038679B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire provided with uneven wear sacrifice protrusions for suppressing uneven wear of adjacent land portions in a circumferential groove.

In a pneumatic tire, particularly a heavy duty pneumatic tire in which a circumferential groove along the circumferential direction is formed on the shoulder side of the tread portion, in order to prevent uneven wear in the land portion on the shoulder side, A partial wear sacrificial protrusion (so-called BCR) is provided at the bottom of the circumferential groove on the shoulder side so as to prevent the wear generated in the land portion from progressing toward the center side (see Patent Document 1).
Japanese Patent Laid-Open No. 2-169305

The main function of the uneven wear sacrificial protrusion is to suppress the uneven wear of the adjacent rib or block by wearing itself to replace a part of the wear of the adjacent rib or block. The sacrificial protrusion was set parallel to the groove.
For example, when the circumferential groove has a zigzag shape, the uneven wear sacrificial protrusions are also formed in a zigzag shape in parallel to the circumferential groove (see FIG. 14 of Patent Document 1).

By the way, if the distance between the uneven wear sacrificial projection and the land portion is shorter, the function of the uneven wear sacrificial projection is more effective. The relative movement with the part is lost, and the function of the uneven wear sacrifice protrusion is lost.
The reason why the uneven wear sacrificial projection and the land part contact each other is that the land part is crushing deformed by a load at the ground contact part (the land part is compressed in the vertical direction, and the side of the land part bulges in the lateral direction), Thereby, it contacts with a partial wear sacrifice protrusion.

Until now, these have been controlled at the position of the uneven wear sacrificial projection while being parallel to the groove.
However, when the circumferential groove has a zigzag shape, even if the uneven wear sacrificial protrusion is arranged in the groove, the uneven wear is still generated from the apex portion of the zigzag shape of the rib. In some cases, uneven wear such as river wear may occur without fully exhibiting.

  In order to suppress the river wear, a method of reducing the swing width has been conventionally used. However, in this method, the edge component (component in the tire width direction) of the circumferential groove that is zigzag-shaped simultaneously is also reduced. There was a problem that wet performance deteriorated.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a pneumatic tire that can effectively suppress uneven wear of a land portion adjacent to a circumferential groove having an amplitude.

  In order to achieve the above object, the invention according to claim 1 is characterized in that a tread includes a circumferential groove extending along a circumferential direction with an amplitude, and a side wall that repeats unevenness in the circumferential direction adjacent to the circumferential groove. A pneumatic tire in which the position of the top is set lower than the tread surface, and a sacrificial wear sacrificial projection that contacts the road surface at the time of ground contact is provided on the groove bottom of the circumferential groove, An interval between the adjacent land portion and the uneven wear sacrifice protrusion is set to a minimum at a portion of the land portion side wall that is convex in a tread plan view.

Next, the operation of the pneumatic tire according to claim 1 will be described.
In the tread plan view, the distance between the land adjacent to the circumferential groove and the sacrificial wear sacrificial projection is minimized at the portion where the land side wall is convex (the top of the mountain), so the tread is grounded and the land is Even when the crushing is deformed, it is possible to avoid that the entire side wall of the land portion contacts the uneven wear sacrifice protrusion.

In addition, even if the land portion comes into contact with the uneven wear sacrificial projection, only the convex portion comes into contact, so the relative movement between the uneven wear sacrificial projection and the land portion is ensured, and the functional deterioration of the uneven wear sacrificial projection can be prevented. .
Furthermore, since the convex part of a land part comes closest to the uneven wear sacrifice protrusion, the partial wear which generate | occur | produces from the convex part of a land part can be suppressed effectively.

Moreover, since it is not necessary to reduce the amplitude of the circumferential groove, an edge component (component in the tire width direction) is ensured, and wet performance can be maintained.
The circumferential groove and the uneven wear sacrificial protrusion may be in the same phase or in opposite phase. Further, the uneven wear sacrificial protrusions may extend linearly in the tire circumferential direction.

As described above, according to the present invention, there is an excellent effect that uneven wear of a land portion adjacent to a circumferential groove having an amplitude can be effectively suppressed.
Further, since it is not necessary to reduce the amplitude of the circumferential groove, the wet performance can be maintained.

A first embodiment of the pneumatic tire of the present invention will be described with reference to FIG.
FIG. 1 shows a pattern (a part) of the tread 12 of the pneumatic tire 10 according to the present embodiment.
The tread 12 is formed with a center circumferential main groove 14 extending in a zigzag shape along the tire circumferential direction (arrow A direction) at the center, and the tire circumferential direction outer side of the center circumferential main groove 14 is also the tire circumferential direction. A shoulder circumferential main groove 16 extending in a zigzag shape along the direction is formed.

Further, the tread 12 is formed with a plurality of crank-shaped lateral grooves 18 between the center circumferential main groove 14 and the shoulder circumferential main groove 16, so that on both sides of the center circumferential main groove 14, A substantially Z-shaped center block 20 is defined.
Further, the tread 12 is formed with a plurality of lateral grooves 22 extending toward the shoulder circumferential main groove 16 and the tread end 12E, whereby a shoulder block 24 is defined on the outer side of the center block 20 in the tire width direction. Yes.

As shown in FIGS. 1 and 2, a rib-shaped uneven wear sacrificial protrusion 26 is formed at the bottom of the shoulder circumferential main groove 16 at a position where the top is set lower than the tread and is in sliding contact with the road surface during ground contact. Are provided continuously.
Here, the uneven wear sacrificial protrusion 26 of the present embodiment extends in a zigzag shape in the circumferential direction in the same phase as the shoulder circumferential main groove 16, but the zigzag amplitude is set smaller than that in the shoulder circumferential main groove 16. Has been.

  Accordingly, the distance between the center block 20 and the uneven wear sacrificial projection 26 is such that the tip of the convex portion of the side wall of the center block 20 in the tread plan view is closest to the uneven wear sacrificial projection 26, and the shoulder block 24. Similarly, the tip of the portion of the side wall of the shoulder block 24 that is convex in the plan view of the tread is closest to the uneven wear sacrificial projection 26 in the interval between the sacrificial wear sacrificial projection 26 and the uneven wear sacrificial projection 26.

(Function)
In the pneumatic tire 10 of the present embodiment, high drainage performance is ensured by the center circumferential main groove 14, the shoulder circumferential main groove 16, the lateral groove 18, and the lateral groove 22 that extend along the tire circumferential direction in the tread 12. .
When the pneumatic tire 10 rotates, due to the difference in diameter between the tread 12 tread surface diameter and the top wear sacrificial projection 26 diameter, the uneven wear sacrificial projection 26 comes into sliding contact with the road surface during contact with the uneven wear sacrificial projection 26. The adjacent shoulder block 24 wears in place of the uneven wear that should occur.

  In particular, by providing the uneven wear sacrificial projection 26 in the shoulder circumferential main groove 16 that divides the shoulder block 24 that is prone to uneven wear, the uneven wear of the shoulder block 24 can be effectively suppressed. Can also be prevented from progressing toward the tire equatorial plane CL.

  Since the distance between the center block 20 and the uneven wear sacrificial projection 26 is minimized at the portion of the block side wall that is convex (the top of the mountain), even if the tread 12 contacts the ground and the center block 20 is crushing deformed, It can be avoided that the entire side wall of the block 20 contacts the uneven wear sacrificial protrusion 26.

Even if the center block 20 comes into contact with the uneven wear sacrificial projection 26, only the vicinity of the tip of the convex portion comes into contact, so that the relative movement between the uneven wear sacrificial projection 26 and the center block 20 is secured, and the uneven wear sacrificial projection 26. Can prevent functional degradation.
Furthermore, since the tip of the convex portion of the center block 20 comes closest to the uneven wear sacrificial protrusion 26, the uneven wear generated from the convex portion of the center block 20 can be effectively suppressed.

Moreover, the uneven wear which generate | occur | produces from the convex part of the shoulder block 24 can be effectively suppressed also about the shoulder block 24 by the same principle.
Moreover, since it is not necessary to reduce the amplitude of the shoulder circumferential direction main groove 16, an edge component (component in the tire width direction) is ensured, and wet performance can be maintained.

In the present embodiment, the zigzag shape of the shoulder circumferential main groove 16 and the zigzag shape of the uneven wear sacrificial protrusion 26 are in the same phase. However, the present invention is not limited to this. However, it suffices that the tip of the convex portion is closest to the uneven wear sacrificial projection 26, and the uneven wear sacrificial projection 26 may extend linearly with respect to the circumferential direction. 16 may extend in a zigzag shape in the circumferential direction with a phase opposite to that of 16.
Furthermore, the land portion arranged on the side of the uneven wear sacrifice protrusion 26 is not limited to the block but may be a rib.

  In the shoulder block 24 that is prone to heel and toe wear, the tread surface of the shoulder block 24 has a substantially arc shape when viewed in a cross section perpendicular to the tire rotation axis, and the stepping end and the kicking end are surrounded by a circle. If set lower than the central part in the direction, the maximum position of the ground pressure when new and at the beginning of wear is the central part in the circumferential direction. As a result, the progress of wear near the stepping end increases, and the progress of heel and toe wear after the initial wear can be delayed.

(Test example)
In order to confirm the effect of the present invention, two types of conventional tires and one type of tire according to the present invention were prepared, and actual vehicle tests were conducted to compare wet performance and uneven wear resistance performance. It was.

Example tire: having the tread pattern described in the above embodiment.
Tire of Conventional Example 1: As shown in FIG. 3, the amplitude of the shoulder circumferential main groove is the same as that of the example, and the interval between the uneven wear sacrificial protrusion and the adjacent block is constant.
Tire of Conventional Example 2: As shown in FIG. 4, the amplitude of the shoulder circumferential main groove is smaller than that of the example, and the distance between the uneven wear sacrifice protrusion and the adjacent block is constant.

(1) Wet performance Road surface: Steel plate surface with water depth of 2 mm Vehicle: 2-D4
Loading: Fixed volume Initial speed: 30 km / h
The braking distance during full braking was measured under the above conditions.
The evaluation is an index display in which the braking distance of Conventional Example 1 is set to 100, and the larger the value, the lower the wet performance.

(2) Uneven wear resistance Vehicle: 2-D4
A test tire was mounted on an actual vehicle, and a general road surface was actually operated, and the volume of uneven wear generated along the shoulder circumferential main groove 16 of the center block at the same travel distance was measured.
The evaluation is represented by an index with the uneven wear volume of the conventional example as 100, and the larger the numerical value, the lower the uneven wear resistance performance.

試験の結果、本発明の適用された実施例のタイヤは、ウエット性能を維持しつつ、耐偏摩耗性能が大幅に向上しているのが分かる。

As a result of the test, it can be seen that the tires of the examples to which the present invention is applied have significantly improved uneven wear resistance while maintaining wet performance.

It is a top view of the tread of the pneumatic tire concerning a 1st embodiment. It is sectional drawing of a shoulder circumferential direction main groove. It is a top view of the tread of the pneumatic tire which concerns on the prior art example 1. It is a top view of the tread of the pneumatic tire which concerns on the prior art example 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Pneumatic tire 12 Tread 16 Shoulder circumferential direction main groove 18 Lateral groove 20 Center block 22 Lateral groove 24 Shoulder block 26 Uneven wear sacrifice protrusion

Claims (4)

The tread is provided with a circumferential groove extending along the circumferential direction with an amplitude, and a land portion having a side wall that repeats unevenness in the circumferential direction adjacent to the circumferential groove, and the position of the top is set lower than the tread. A pneumatic tire provided with uneven wear sacrificial protrusions in contact with the road surface at the time of contact on the groove bottom of the circumferential groove,
The pneumatic tire according to claim 1, wherein an interval between the land portion adjacent to the circumferential groove and the uneven wear sacrificial protrusion is set to a minimum at a convex portion of the land portion side wall in a tread plan view.   The pneumatic tire according to claim 1, wherein the circumferential groove and the uneven wear sacrifice protrusion are in phase.   The pneumatic tire according to claim 1, wherein the circumferential groove and the uneven wear sacrificial protrusion are in opposite phases.   The pneumatic tire according to claim 1, wherein the uneven wear sacrificial protrusion extends linearly in the tire circumferential direction.

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