JP7306176B2 - tire - Google Patents

Description

The present invention relates to tires.

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

JP 2016-203663 A

In general, 3-rib tires have large widths in each land portion and are expected to have excellent wear resistance performance. On the other hand, the 3-rib tire tends to be inferior in drainage capacity because it has only two circumferential grooves. In addition, in the three-rib tire, since the length of the edges of the circumferential grooves is also short, there is a tendency that the frictional force in the tire axial direction due to these edges is insufficient. For the reasons described above, it is desired that the three-rib tire have improved wet performance.

SUMMARY OF THE INVENTION The present invention has been devised in view of the problems described above, and a main object of the present invention is to improve wet performance while maintaining good wear resistance performance 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 equator, a crown land portion between the circumferential grooves, It is a three-rib pattern consisting of a pair of shoulder land portions on both outer sides of the circumferential groove. 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 closing recess in 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 closing recess in the tire circumferential direction is greater than the length in the tire axial direction.

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

In the tire of the present invention, the length of the closing recess in the tire circumferential direction is greater than the length in the tire axial direction, and the width of the closing recess in the direction perpendicular to the length direction is the width of the longitudinal narrow groove. 3.0 to 4.0 times is desirable.

In the tire of the present invention, it is preferable that the closed recess and the longitudinal narrow groove are provided on the tire equator.

In the tire of the present invention, it is preferable that the closing recesses have a depth smaller than that of the longitudinal grooves.

In the tire of the present invention, it is desirable that the depth of the closing recess is 25% to 40% of the depth of the longitudinal groove.

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

In the tire of the present invention, the closed recess has a length in the tire circumferential direction that is greater than a length in the tire axial direction, and the first lateral narrow groove communicates with one end of the closed recess in the tire circumferential direction. It is desirable to have

In the tire of the present invention, it is preferable that the second lateral narrow groove communicates with the end portion of the closing recess on the other side in the tire circumferential direction.

In the tire of the present invention, it is preferable that the first lateral narrow groove and the second lateral narrow groove are inclined in opposite directions with respect to the axial direction of the tire.

In the tire of the present invention, it is preferable that each of the first lateral narrow groove and the second lateral narrow groove has a depth greater than that of the closing recess.

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

In the tire of the present invention, it is preferable that the depth of the first lateral narrow 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 narrow 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 greater than the length in the tire axial direction, and the groove width of the first lateral narrow groove is in the direction orthogonal to the length direction of the closed recess. 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 greater than the length in the tire axial direction, and the groove width of the second lateral narrow groove is in the direction orthogonal to the length direction of the closed recess. Preferably 40% to 50% of the width.

The tread portion of the tire of the present invention includes a pair of circumferential grooves continuously extending in the tire circumferential direction on both sides of the tire equator, a crown land portion between the circumferential grooves, and a pair of outer sides of the circumferential grooves. It is a 3-rib pattern consisting of a shoulder land portion of The crown land portion is provided with a closed concave portion having a closed shape inside the crown land portion and a longitudinal narrow groove extending in the tire circumferential direction. Both the closed concave portion and the vertical thin groove prevent excessive reduction in rigidity of the crown land portion, and improve drainage performance while maintaining wear resistance performance.

In the tire of the present invention, a plurality of 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 closing recesses adjacent in the tire circumferential direction. The closed recesses and the vertical thin grooves can take in water from the closed recesses side during wet running and discharge it in the longitudinal direction of the tire through the vertical thin grooves, thereby exhibiting excellent drainage performance. In addition, the closed concave portion and the vertical narrow groove provide frictional force in the axial direction of the tire during wet running, thereby enhancing wet performance.

1 is a developed view of a tread portion of a tire according to one embodiment of the present invention; FIG. FIG. 2 is an enlarged view of the crown land portion of FIG. 1; FIG. 2 is an enlarged view of a shoulder land portion in FIG. 1; It is an enlarged view of the crown land part of a comparative example.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a developed view of a tread portion 2 of a tire 1 showing one embodiment of the present invention. As shown in FIG. 1, the tire 1 of the present invention is suitably used as a pneumatic tire for small trucks, for example. However, the present invention is not limited to such a mode of use.

The tread portion 2 includes 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 grooves on both outer sides of the circumferential grooves 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 edge Te.

In the case of a pneumatic tire, the "tread edge Te" is a flat surface with a camber angle of 0 degrees when a regular load is applied to the tire 1 in a regular state, which is mounted on a regular rim and filled with regular internal pressure. This is the outermost grounding position in the axial direction of the tire when grounded. Unless otherwise specified, the dimensions of each part of the tire are values measured under normal conditions.

A "regular rim" is a rim defined for each tire in a standard system including the standard on which the tire is based. Then it is "Measuring Rim".

"Regular internal pressure" is the air pressure specified for each tire by each standard in the standard system including the standards on which tires are based. Maximum value described in VARIOUS COLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO.

"Normal load" is the load defined for each tire by each standard in the standard system including the standards on which tires are based. AT VARIOUS COLD INFLATION PRESSURES", and for ETRTO, it is "LOAD CAPACITY".

The axial distance L1 from the tire equator C to the groove centerline of the circumferential groove 3 is preferably 0.13 to 0.20 times the tread width TW, for example. The tread width TW is the distance in the tire axial direction between the tread edges Te, Te in the normal state.

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

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 circumferential grooves 3 can exhibit excellent drainage performance.

An enlarged view of the crown land portion 4 is shown in FIG. 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). be.

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

The longitudinal narrow groove 11 extends in the tire circumferential direction. The vertical thin grooves 11 have a groove width smaller than that of the circumferential grooves 3 and extend so as to communicate with closed recesses 10 adjacent in the tire circumferential direction.

Both the closed concave portion 10 and the vertical thin groove 11 prevent excessive reduction in rigidity of the crown land portion 4 and improve drainage performance while maintaining wear resistance performance. In addition, the closed recess 10 and the vertical thin groove 11 can take in water from the closed recess 10 side during wet running and discharge it in the longitudinal direction of the tire through the vertical thin groove 11, thereby exhibiting excellent drainage performance. In addition, the closed recess 10 and the vertical thin groove 11 provide frictional force in the axial direction of the tire during wet running, thereby enhancing wet performance.

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

The vertical narrow groove 11 extends linearly parallel to the tire circumferential direction, for example. However, it is not limited to such a mode, and the vertical thin grooves 11 may extend in a wavy shape. The length L2 of the longitudinal narrow groove 11 in the tire circumferential direction is 21 to 35 mm.

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

The depth of the vertical thin grooves 11 is preferably smaller than the depth of the circumferential grooves 3, for example. Specifically, the depth of the vertical thin grooves 11 is 70% to 90% of the depth of the circumferential grooves 3 . Such vertical thin grooves 11 improve wear resistance performance and wet performance in a well-balanced manner.

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

The closing recess 10 is, for example, a vertically elongated groove whose length in the tire circumferential direction is greater than its length in the tire axial direction. The closed recessed portion 10 of the present embodiment has two longitudinal edges 10a extending in the tire circumferential direction inclined at an angle of 10° or less with respect to the tire circumferential direction. Also, the two vertical edges 10a are parallel to each other.

A lateral edge 10b at the end of the closing recess 10 in the tire circumferential direction is arranged at an angle of 20 to 35° to the axial direction of the tire. Further, the lateral edge 10b at one end and the lateral edge 10b at the other end are inclined in opposite directions to the axial direction of the tire.

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

From a similar point of view, the width W3 of the closing recess 10 (the width in the direction perpendicular to the length direction) is, for example, 2.0 to 6.0 times the groove width W2 of the vertical narrow groove 11, and is preferably is 3.0 to 4.0 times.

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

The crown land portion 4 has a plurality of first horizontal narrow grooves 16 extending from one of the circumferential grooves 3 to the closed recess 10 and a plurality of second horizontal narrow grooves 17 extending from the other of the circumferential grooves 3 to the closed recess 10. is provided. The first horizontal narrow grooves 16 and the second horizontal narrow grooves 17 help improve 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 narrow groove 17 communicates with, for example, the end of the closing recess 10 on the other side in the tire circumferential direction.

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

By arranging the first horizontal thin groove 16 and the second horizontal thin groove 17 in the direction of inclination described above, the angle between the first horizontal thin groove 16 and the closing recess 10 is an obtuse angle and the second horizontal thin groove 17 is obtuse. The angle between the groove 17 and the closing recess 10 is acute. The first lateral narrow groove 16 and the second lateral narrow groove 17 are inclined at an angle θ1 of 20 to 35° with respect to the axial direction of the tire, for example. Such first lateral narrow grooves 16 and second lateral narrow grooves 17 can exhibit frictional force also in the axial direction of the tire during wet running.

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

From a similar point of view, the first horizontal narrow groove 16 and the second horizontal narrow groove 17 each have a depth smaller than that of the vertical narrow 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 closing recess 10. As shown in FIG. 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. As shown in FIG. 3, the axial width W6 of the shoulder land portion 5 is, for example, 0.25 to 0.35 times the tread width TW. Moreover, the shoulder land portion 5 of the present embodiment is, for example, a rib continuously extending in the tire circumferential direction. Such a shoulder land portion 5 has high rigidity and is useful for enhancing steering stability.

A plurality of inner grooves 21 , outer recesses 22 , inner thin grooves 23 and outer thin grooves 24 are provided in the shoulder land portion 5 .

The inner groove 21 , for example, communicates with the circumferential groove 3 and is interrupted within the shoulder land portion 5 . The groove width W7 of the inner groove 21 is greater than the width W3 of the closed recess 10 (shown in FIG. 2, and so on). The width of the inner groove 21 of the present embodiment increases 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 opens at the tread edge Te. The axial length L6 of the outer recess 22 is preferably greater than the width W3 of the closing recess 10 . Moreover, 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 closing 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 , for example, extends from the circumferential groove 3 and is discontinued within the shoulder land portion 5 . The outer narrow groove 24 extends from the tread edge Te and is discontinued within the shoulder land portion 5 . Such inner thin grooves 23 and outer thin grooves 24 help to exhibit excellent steering stability.

The axial length L7 of the inner narrow groove 23 and the axial length L8 of the outer narrow groove 24 are, for example, 5% to 20% of the axial width W6 of the shoulder land portion 5. . It is desirable that the length L9 of the outer thin groove 24 is greater than the length L8 of the inner thin 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 can be implemented in various ways.

A pneumatic tire of size 195/75R15 having the basic pattern shown in FIG. As a comparative example, a prototype tire having a crown land portion a shown in FIG. 4 was produced. 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 recesses and longitudinal narrow grooves of the present invention. Moreover, the tire of the comparative example is the same as the tire shown in FIG. 1 except for the above configuration. Each test tire was tested for wet and wear performance. 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>
The above test vehicle was used to measure the time when it ran on a circuit course consisting of wet road surfaces. The result is the reciprocal of the time, and is indicated by an index with the value of the comparative example being 100. A higher value indicates better wet performance.

<Abrasion resistance performance>
After driving the test vehicle for a certain distance, the depth of the remaining circumferential groove was measured. The results are scored with the depth of the comparative example being 100, and the larger the number, the better the wear resistance performance.
The results of the tests are shown in Tables 1-2.

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

2 Tread Portion 3 Circumferential Groove 4 Crown Land Portion 5 Shoulder Land Portion 10 Closed Recess 11 Longitudinal Groove

Claims (17)

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

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