JP2021041765A - tire - Google Patents

Abstract

To improve wet performance of a three-rib tire while maintaining excellent abrasion resistant performance.SOLUTION: A tire has a tread part 2. The tread part 2 is a three-rib pattern composed of a pair of circumferential grooves 3 continuously extending in a tire circumferential direction on both sides of a tire equator, a crown land part 4, and a pair of shoulder land parts 5. The crown land part 4 is provided with a closed recessed part 10 having a closed shape and a vertical striation 11 extending in the tire circumferential direction. A plurality of closed recessed parts 10 are formed in the tire circumferential direction. The vertical striation 11 has a groove width smaller than the circumferential groove 3, and extends so as to provide communication with the closed recessed parts 10 adjacent in the circumferential direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to a tire.

Various tires (hereinafter, may be referred to as "three-rib tires") in which the tread portion is formed by three land portions divided by two circumferential grooves have been proposed. (For example, see Patent Document 1 below.).

Japanese Unexamined Patent Publication No. 2016-203663

In general, 3-rib tires are expected to have excellent wear resistance due to the large width of each land area. On the other hand, the 3-rib tire tends to be inferior in drainage capacity because it has as few circumferential grooves as two. Further, since the edge length of the circumferential groove is also reduced in the 3-rib tire, the frictional force in the tire axial direction due to these edges tends to be insufficient. For the above reasons, the 3-rib tire is desired to have improved wet performance.

The present invention has been devised in view of the above problems, and a main object of the present invention is to improve wet performance while maintaining good wear resistance in a 3-rib tire.

The present invention is a tire having a tread portion, wherein the tread portion includes a pair of circumferential grooves extending continuously in the tire circumferential direction on both sides of the tire equatorial line, and a crown land portion between the circumferential grooves. It is a 3-rib pattern consisting of a pair of shoulder land portions on both outer sides of the circumferential groove, and the crown land portion has a closed recess having a closed shape in the crown land portion and a vertical narrowness extending in the tire circumferential direction. A groove is provided, and a plurality of the closing recesses are formed in the tire circumferential direction, and the vertical narrow groove has a groove width smaller than the circumferential groove and is adjacent to the tire circumferential direction. It extends so as to communicate with the recess.

In the tire of the present invention, it is desirable that the length of the closed recess in the tire circumferential direction is larger than the length in the tire axial direction.

In the tire of the present invention, it is desirable that the length of the vertical narrow groove in the tire circumferential direction is 21 to 35 mm.

In the tire of the present invention, the length of the closed recess in the tire circumferential direction is larger than the length in the tire axial direction, and the width in the direction orthogonal to the length direction of the closed recess is the groove width of the vertical narrow groove. It is desirable that it is 3.0 to 4.0 times.

In the tire of the present invention, it is desirable that the closed recess and the vertical groove are provided on the equator of the tire.

In the tire of the present invention, it is desirable that the closed recess has a depth smaller than that of the vertical groove.

In the tire of the present invention, the depth of the closed recess is preferably 25% to 40% of the depth of the vertical groove.

In the tire of the present invention, in the land portion of the crown, a plurality of first lateral narrow grooves extending from one of the circumferential grooves to the closed recess and a plurality of second lateral grooves extending from the other of the circumferential grooves to the closed recess. It is desirable that a horizontal narrow groove is provided.

In the tire of the present invention, the length of the closed recess in the tire circumferential direction is larger than the length in the tire axial direction, and the first lateral groove communicates with one end of the closed recess in the tire circumferential direction. It is desirable to do.

In the tire of the present invention, it is desirable that the second lateral groove communicates with the other end of the closed recess in the tire circumferential direction.

In the tire of the present invention, it is desirable that the first lateral groove and the second lateral groove are inclined in the direction opposite to the tire axial direction.

In the tire of the present invention, it is desirable that the first lateral groove and the second lateral groove each have a depth larger than that of the closed recess.

In the tire of the present invention, it is desirable that the first horizontal groove and the second horizontal groove each have a depth smaller than that of the vertical groove.

In the tire of the present invention, it is desirable that the depth of the first lateral groove is 2.0 to 3.0 times the depth of the closed recess.

In the tire of the present invention, it is desirable that the depth of the second lateral groove is 2.0 to 3.0 times the depth of the closed recess.

In the tire of the present invention, the length of the closed recess in the tire circumferential direction is larger than the length in the tire axial direction, and the groove width of the first lateral narrow groove is in a direction orthogonal to the length direction of the closed recess. It is preferably 40% to 50% of the width.

In the tire of the present invention, the length of the closed recess in the tire circumferential direction is larger than the length in the tire axial direction, and the groove width of the second lateral narrow groove is in a direction orthogonal to the length direction of the closed recess. It is preferably 40% to 50% of the width.

The tread portion of the tire of the present invention includes a pair of circumferential grooves extending continuously on both sides of the tire equatorial line in the tire circumferential direction, a crown land portion between the circumferential grooves, and a pair of outer sides of the circumferential groove. It is a 3-rib pattern consisting of the shoulder land part of. The land portion of the crown is provided with a closed recess having a closed shape in the land portion of the crown and a vertical narrow groove extending in the tire circumferential direction. Both the closed recess and the vertical groove prevent an excessive decrease in rigidity of the land portion of the crown and enhance drainage performance while maintaining wear resistance.

In the tire of the present invention, a plurality of the closed recesses are formed in the tire circumferential direction. The vertical narrow groove has a groove width smaller than that of the circumferential groove, and extends so as to communicate with the closed recess adjacent to the tire circumferential direction. The closed recess and the vertical narrow groove can take in water from the closed recess side during wet running and discharge it in the front-rear direction in the tire circumferential direction through the vertical narrow groove, and exhibit excellent drainage. In addition, the closed recess and the vertical groove provide frictional force in the tire axial direction during wet running to enhance wet performance.

It is a development view of the tread part of the tire of one Embodiment of this invention. It is an enlarged view of the crown land part of FIG. It is an enlarged view of the shoulder land part of FIG. It is an enlarged view of the crown land part of a comparative example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a developed view of a tread portion 2 of a tire 1 showing an embodiment of the present invention. As shown in FIG. 1, the tire 1 of the present invention is suitably used as, for example, a pneumatic tire for a light truck. However, the present invention is not limited to such usage.

The tread portion 2 is a pair of circumferential grooves 3 extending continuously in the tire circumferential direction on both sides in the tire circumferential direction, a crown land portion 4 between the circumferential grooves 3, and a pair of outer sides of the circumferential groove 3. It is a 3-rib pattern consisting of a shoulder land portion 5. The crown land portion 4 is provided on the tire equator C, and the shoulder land portion 5 includes the tread end Te.

In the case of a pneumatic tire, the "tread end Te" is a flat tire 1 with a normal load applied to a tire 1 in a normal state, which is rim-assembled on a regular rim and filled with a regular internal pressure, at a camber angle of 0 degrees. This is the most outer contact position in the tire axial direction when the tire is grounded. Unless otherwise specified, the dimensions and the like of each part of the tire are values measured in a normal state.

A "regular rim" is a rim defined for each tire in the standard system including the standard on which the tire is based. For example, "standard rim" for JATTA, "Design Rim" for TRA, and ETRTO. If so, it is "Measuring Rim".

"Regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which the tire is based. For JATMA, "maximum air pressure", for TRA, the table "TIRE LOAD LIMITS AT" The maximum value described in "VARIOUS COLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO.

"Regular load" is the load defined for each tire in the standard system including the standard on which the tire is based. For JATMA, "maximum load capacity", for TRA, the table "TIRE LOAD LIMITS" The maximum value described in "AT VARIOUS COLD INFLATION PRESSURES", or "LOAD CAPACITY" for ETRTO.

It is desirable that the distance L1 in the tire axial direction from the tire equator C to the groove center line of the circumferential groove 3 is, for example, 0.13 to 0.20 times the tread width TW. The tread width TW is the distance in the tire axial direction between the tread end Te and Te in the normal state.

The groove width of each circumferential groove 3 is preferably, for example, 6% to 9% of the tread width TW. In the case of the heavy-duty tire of the present embodiment, the depth of each circumferential groove is preferably 5 to 15 mm, for example.

In the circumferential groove 3 of the present embodiment, for example, the groove edge on the crown land portion 4 side extends in a zigzag shape, and the groove edge on the shoulder land portion 5 side extends linearly. Such a circumferential groove 3 can exhibit excellent drainage performance.

FIG. 2 shows an enlarged view of the land portion 4 of the crown. As shown in FIG. 2, the width W1 of the crown land portion 4 in the tire axial direction is, for example, 0.20 to 0.30 times the tread width TW (shown in FIG. 1 and the same applies hereinafter). is there.

The land portion 4 of the crown is provided with a closed recess 10 and a vertical narrow groove 11. The closing recess 10 has a closed shape within the land portion 4 of the crown. Further, a plurality of closed recesses 10 are formed in the tire circumferential direction.

The vertical groove 11 extends in the tire circumferential direction. The vertical narrow groove 11 has a groove width smaller than that of the circumferential groove 3 and extends so as to communicate with the closed recess 10 adjacent to the tire circumferential direction.

Both the closing recess 10 and the vertical groove 11 prevent the crown land portion 4 from being excessively lowered in rigidity, and enhance the drainage performance while maintaining the wear resistance performance. Further, the closed recess 10 and the vertical narrow groove 11 can take in water from the closed recess 10 side during wet running and discharge the water through the vertical narrow groove 11 in the front-rear direction in the tire circumferential direction, and exhibit excellent drainage. Further, the closed recess 10 and the vertical groove 11 provide a frictional force in the tire axial direction during wet running to enhance wet performance.

The groove width W2 of the vertical narrow groove 11 is, for example, 50% or less, more preferably 30% or less of the groove width of the circumferential groove 3. The groove width W2 of the vertical narrow groove 11 of the present embodiment is 0.5 to 2.0 mm. Such a vertical groove 11 enhances wet performance while maintaining the rigidity of the crown land portion 4.

The vertical narrow groove 11 extends linearly in parallel with the tire circumferential direction, for example. However, the present invention is not limited to such an aspect, and the vertical groove 11 may extend in a wavy shape. The length L2 of the vertical groove 11 in the tire circumferential direction is 21 to 35 mm.

The vertical groove 11 is arranged, for example, in the central portion of the crown land portion 4 in the tire axial direction. The distance L3 in the tire axial direction from the edge of the circumferential groove 3 to the edge of the vertical narrow groove 11 is 40% to 60% of the width W1 in the tire axial direction of the crown land portion 4. As a preferred embodiment, the vertical groove 11 of the present embodiment is provided on the tire equator C.

It is desirable that the depth of the vertical groove 11 is smaller than the depth of the circumferential groove 3, for example. Specifically, the depth of the vertical groove 11 is 70% to 90% of the depth of the circumferential groove 3. Such a vertical groove 11 improves wear resistance and wet performance in a well-balanced manner.

The closing recess 10 is provided, for example, in the central portion of the crown land portion 4 in the tire axial direction. The distance L4 in the tire axial direction from the groove edge of the circumferential groove 3 to the groove edge of the closed recess 10 is, for example, 40% to 60% of the width W1 of the crown land portion 4 in the tire axial direction. The closing recess 10 of the present embodiment is provided on the tire equator C together with the vertical groove 11. As a result, the closed recess 10 and the vertical groove 11 exhibit even higher drainage performance.

The closed recess 10 is, for example, a vertically long groove whose length in the tire circumferential direction is larger than the length in the tire axial direction. In the closed recess 10 of the present embodiment, two vertical edges 10a extending in the tire circumferential direction are inclined at an angle of 10 ° or less with respect to the tire circumferential direction. Further, the two vertical edges 10a are parallel to each other.

The lateral edge 10b at the end of the closed recess 10 in the tire circumferential direction is arranged at 20 to 35 ° with respect to the tire axial direction. Further, the lateral edge 10b at one end and the lateral edge 10b at the other end are inclined in opposite directions with respect to the tire axial direction.

It is desirable that the length L5 of the closing recess 10 in the tire circumferential direction is smaller than, for example, the length L2 of the vertical groove 11 in the tire circumferential direction. Specifically, the length L5 of the closed recess 10 is 30% to 50% of the length L2 of the vertical groove 11. Such a closed recess 10 enhances the wet performance while maintaining the wear resistance performance of the crown land portion 4.

From the same viewpoint, the width W3 of the closed recess 10 (the width in the direction orthogonal to the length direction) is, for example, 2.0 to 6.0 times the groove width W2 of the vertical narrow groove 11, which is desirable. Is 3.0 to 4.0 times.

It is desirable that the closing recess 10 has a depth smaller than that of the vertical groove 11. Specifically, the depth of the closed recess 10 is 25% to 40% of the depth of the vertical groove 11. As a result, the progress of wear becomes uniform around the closed recess 10 and around the vertical narrow groove 11, and uneven wear of the crown land portion 4 is suppressed.

The land portion 4 of the crown includes a plurality of first horizontal grooves 16 extending from one of the circumferential grooves 3 to the closed recess 10, and a plurality of second horizontal grooves 17 extending from the other of the circumferential grooves 3 to the closed recess 10. Is provided. The first lateral groove 16 and the second lateral groove 17 are useful for enhancing wet performance.

The first lateral narrow groove 16 communicates with, for example, one end of the closing recess 10 in the tire circumferential direction. The second lateral groove 17 communicates with, for example, the other end of the closing recess 10 in the tire circumferential direction.

It is desirable that the first lateral groove 16 and the second lateral groove 17 are inclined in the opposite directions to the tire axial direction. In the present embodiment, the direction of inclination of the first horizontal fine groove 16 is the same as the direction of inclination of the horizontal edge 10b at the end of the closed recess 10 with which the first horizontal fine groove 16 communicates. Further, the direction of inclination of the second horizontal fine groove 17 is the same as the direction of inclination of the horizontal edge 10b at the end of the closing recess 10 with which the second horizontal fine groove 17 communicates. In a more preferred embodiment, one of the edges of the first lateral groove 16 is continuous with the lateral edge 10b at the end of the closure recess 10. The same applies to the second horizontal narrow groove 17. As a result, uneven wear around the closed recess 10 is suppressed.

By arranging the first horizontal narrow groove 16 and the second horizontal fine groove 17 in the above-mentioned inclined directions, the angle between the first horizontal fine groove 16 and the closing recess 10 is an acute angle, and the second horizontal groove 16 is an acute angle. The angle between the groove 17 and the closing recess 10 is an acute angle. The first lateral groove 16 and the second lateral groove 17 are inclined at an angle θ1 of, for example, 20 to 35 ° with respect to the tire axial direction. Such a first horizontal fine groove 16 and a second horizontal fine groove 17 can exert a frictional force in the tire axial direction during wet running.

It is desirable that the first horizontal groove 16 and the second horizontal groove 17 each have a depth larger than that of the closed recess 10. The depth of the first lateral groove 16 is 2.0 to 3.0 times the depth of the closed recess 10. The depth of the second lateral groove 17 is 2.0 to 3.0 times the depth of the closed recess 10. Such a first horizontal fine groove 16 and a second horizontal fine groove 17 enhance the wear resistance performance and the wet performance in a well-balanced manner.

From the same viewpoint, the first horizontal groove 16 and the second horizontal fine groove 17 each have a depth smaller than that of the vertical fine groove 11.

The groove width W4 of the first lateral narrow groove 16 is, for example, 10% to 70%, preferably 40% to 50% of the width W3 of the closed recess 10. Similarly, the groove width W5 of the second lateral narrow groove 17 is, for example, 10% to 70%, preferably 40% to 50% of the width W3 of the closed recess 10.

FIG. 3 shows an enlarged view of the shoulder land portion 5. As shown in FIG. 3, the width W6 of the shoulder land portion 5 in the tire axial direction is, for example, 0.25 to 0.35 times the tread width TW. Further, the shoulder land portion 5 of the present embodiment is, for example, a rib that continuously extends in the tire circumferential direction. Such a shoulder land portion 5 has high rigidity and is useful for improving steering stability.

The shoulder land portion 5 is provided with a plurality of inner grooves 21, outer recesses 22, inner fine grooves 23, and outer fine grooves 24, respectively.

The inner groove 21 communicates with, for example, the circumferential groove 3 and is interrupted in the shoulder land portion 5. The groove width W7 of the inner groove 21 is larger than the width W3 of the closing recess 10 (shown in FIG. 2 and the same applies hereinafter). The inner groove 21 of the present embodiment has a groove width that expands toward the circumferential groove 3 side. Such an inner groove 21 enhances wet performance while maintaining the rigidity of the shoulder land portion 5.

The outer recess 22 is opened at the tread end Te. It is desirable that the length L6 of the outer recess 22 in the tire axial direction is larger than the width W3 of the closing recess 10. Further, it is desirable that the length L7 of the outer recess 22 in the tire circumferential direction is smaller than the length L5 of the closed recess 10 in the tire circumferential direction. As a result, the progress of wear of the crown land portion 4 and the shoulder land portion 5 tends to be uniform, and uneven wear is suppressed.

The inner narrow groove 23 extends from the circumferential groove 3 and is interrupted in the shoulder land portion 5, for example. The outer groove 24 extends from the tread end Te and is interrupted in the shoulder land portion 5. Such an inner groove 23 and an outer groove 24 are useful for exhibiting excellent steering stability.

The length L7 of the inner groove 23 in the tire axial direction and the length L8 of the outer groove 24 in the tire axial direction are, for example, 5% to 20% of the width W6 of the shoulder land portion 5 in the tire axial direction. .. It is desirable that the length L9 of the outer groove 24 is larger than the length L8 of the inner groove 23.

Although the tire of one embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment described above, and may be modified to various embodiments.

A size 195 / 75R15 pneumatic tire having the basic pattern of FIG. 1 was prototyped based on the specifications in Table 1. As a comparative example, a tire having a crown land portion a shown in FIG. 4 was prototyped. As shown in FIG. 4, the crown land portion a of the comparative example is provided with a plurality of lateral grooves b extending in the tire axial direction, and is not provided with the closing recess and the vertical narrow groove of the present invention. Further, the tire of the comparative example is the same as the tire shown in FIG. 1 except for the above-described configuration. The wet performance and wear resistance of each test tire were tested. The common specifications and test methods for each test tire are as follows.
Mounting rim: 15 x 5.0
Tire internal pressure: 600kPa
Test vehicle: 2t truck Tire mounting position: All wheels

<Wet performance>
With the above test vehicle, the time when traveling on a circuit course consisting of a wet road surface was measured. The result is the reciprocal of the time, and is shown by an exponent with the value of the comparative example as 100. The larger the value, the better the wet performance.

<Abrasion resistance>
After running the test vehicle for a certain distance, the depth of the remaining circumferential groove was measured. The result is a score with the depth of the comparative example as 100, and the larger the value, the better the wear resistance performance.
The test results are shown in Tables 1-2.

As a result of the test, it was confirmed that the tire of the example exhibited excellent wet performance while maintaining wear resistance.

2 Tread part 3 Circumferential groove 4 Crown land part 5 Shoulder land part 10 Closing recess 11 Vertical narrow groove

Claims (17)

A tire with a tread
The tread portion includes a pair of circumferential grooves extending continuously on both sides of the tire equatorial line in the tire circumferential direction, a crown land portion between the circumferential grooves, and a pair of shoulder land portions on both outer sides of the circumferential groove. It is a 3-rib pattern consisting of
The land portion of the crown is provided with a closed recess having a closed shape in the land portion of the crown and a vertical narrow groove extending in the tire circumferential direction.
A plurality of the closed recesses are formed in the tire circumferential direction.
The vertical narrow groove has a groove width smaller than that of the circumferential groove and extends so as to communicate with the closed recess adjacent to the tire circumferential direction.
tire. The tire according to claim 1, wherein the closed recess has a length in the tire circumferential direction larger than a length in the tire axial direction. The tire according to claim 1 or 2, wherein the length of the vertical narrow groove in the tire circumferential direction is 21 to 35 mm. The length of the closed recess in the tire circumferential direction is larger than the length in the tire axial direction.
The tire according to any one of claims 1 to 3, wherein the width in the direction orthogonal to the length direction of the closed recess is 3.0 to 4.0 times the groove width of the vertical narrow groove. The tire according to any one of claims 1 to 4, wherein the closed recess and the vertical groove are provided on the equator of the tire. The tire according to any one of claims 1 to 5, wherein the closed recess has a depth smaller than that of the vertical groove. The tire according to any one of claims 1 to 6, wherein the depth of the closed recess is 25% to 40% of the depth of the vertical groove. The land portion of the crown is provided with a plurality of first transverse grooves extending from one of the circumferential grooves to the closed recess, and a plurality of second transverse grooves extending from the other of the circumferential grooves to the closed recess. The tire according to any one of claims 1 to 7. The length of the closed recess in the tire circumferential direction is larger than the length in the tire axial direction.
The tire according to claim 8, wherein the first lateral groove communicates with one end of the closed recess on one side in the tire circumferential direction. The tire according to claim 9, wherein the second lateral groove communicates with the other end of the closed recess in the tire circumferential direction. The tire according to any one of claims 8 to 10, wherein the first lateral groove and the second lateral groove are inclined in a direction opposite to the tire axial direction. The tire according to any one of claims 8 to 11, wherein the first lateral groove and the second lateral groove each have a depth larger than that of the closed recess. The tire according to any one of claims 8 to 12, wherein the first horizontal groove and the second horizontal groove each have a depth smaller than that of the vertical groove. The tire according to any one of claims 8 to 13, wherein the depth of the first lateral groove is 2.0 to 3.0 times the depth of the closed recess. The tire according to any one of claims 8 to 14, wherein the depth of the second lateral groove is 2.0 to 3.0 times the depth of the closed recess. The length of the closed recess in the tire circumferential direction is larger than the length in the tire axial direction.
The tire according to any one of claims 8 to 15, wherein the groove width of the first lateral narrow groove is 40% to 50% of the width in the direction orthogonal to the length direction of the closed recess. The length of the closed recess in the tire circumferential direction is larger than the length in the tire axial direction.
The tire according to any one of claims 8 to 16, wherein the groove width of the second lateral narrow groove is 40% to 50% of the width in the direction orthogonal to the length direction of the closed recess.

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