JP2023124165A - tire - Google Patents

Abstract

To provide a tire that can exert excellent wet performance, while maintaining steering stability on a dry road surface.SOLUTION: A tire has a tread part. The tread part includes a crown land part. The crown land part is provided with a plurality of first crown sipes 41 extending from a first vertical edge 15a and having a terminating end 41a in a tread surface 15s, and a plurality of second crown sipes 42 extending from a second vertical edge 15b and having a terminating end 42a in the tread surface 15s. The first crown sipes 41 and the second crown sipes 42 are mutually inclined in the same direction with respect to a tire axial direction. A distance L4 in a tire circumferential direction between an outer end 41b at the first vertical edge 15a side of the first crown sipe 41 and an outer end 42b at the second vertical edge 15b side of the second crown sipe 42 is equal to 10% or less of a first pitch length in the tire circumferential direction of the first crown sipe 41.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to tires.

Patent Literature 1 below proposes a tire in which a plurality of crown sipes are provided in a crown land portion. By improving the crown sipe, the pneumatic tire is expected to improve steering stability on dry road surfaces and wet performance.

JP 2019-094009 A

In recent years, as the performance of vehicles has improved, there has been a demand for further improvements in steering stability and wet performance on dry road surfaces.

The present disclosure has been devised in view of the actual situation as described above, and a main object thereof is to provide a tire capable of exhibiting excellent wet performance while maintaining steering stability on dry road surfaces.

The present disclosure is a tire having a tread portion, the tread portion comprising a first tread end, a second tread end, and a crown land provided between the first tread end and the second tread end. The crown land portion includes a first longitudinal edge extending in the tire circumferential direction on the first tread end side, a second longitudinal edge extending in the tire circumferential direction on the second tread end side, and the first a longitudinal edge and a tread surface between said second longitudinal edge, said crown land portion including a plurality of first crown sipes extending from said first longitudinal edge and having discontinuities in said tread surface; and a plurality of second crown sipes extending from the second longitudinal edge and having discontinuous ends within the tread surface, wherein each of the first crown sipes and each of the second crown sipes extend in the axial direction of the tire. and in the tire circumferential direction between the outer end of the first crown sipe on the side of the first longitudinal edge and the outer end of the second crown sipe on the side of the second longitudinal edge. The tire, wherein the distance is 10% or less of the length of one pitch of the first crown sipe in the tire circumferential direction.

By adopting the above configuration, the tire of the present disclosure can exhibit excellent wet performance while maintaining steering stability on dry road surfaces.

1 is an exploded view of a tread portion showing an embodiment of the present disclosure; FIG. FIG. 2 is an enlarged view of the crown land portion of FIG. 1; 3 is an enlarged view of a first crown sipe, a second crown sipe, a third crown sipe and a fourth crown sipe of FIG. 2; FIG. 3 is a cross-sectional view taken along line EE of FIG. 2; FIG. FIG. 2 is an enlarged view of a first middle land portion of FIG. 1; FIG. 6 is an enlarged view of the first middle lateral groove and the second middle lateral groove of FIG. 5; FIG. 6 is a cross-sectional view taken along line AA of FIG. 5; FIG. 6 is a cross-sectional view taken along line BB of FIG. 5; 6 is a cross-sectional view taken along line CC of FIG. 5; FIG. FIG. 6 is a cross-sectional view taken along line DD of FIG. 5; FIG. 2 is an enlarged view of a second middle land portion of FIG. 1; FIG. 12 is a cross-sectional view taken along line FF of FIG. 11; FIG. 12 is a cross-sectional view taken along line GG of FIG. 11; FIG. 10 is an enlarged view of a second middle land portion of another embodiment of the present disclosure; 4 is an enlarged view of the crown land portion of Example 1. FIG. It is an enlarged view of the crown land part of a comparative example.

An embodiment of the present disclosure 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 an embodiment of the present disclosure. The tire 1 of the present embodiment is, for example, a winter tire and is suitably used as a pneumatic tire for passenger cars. However, the present disclosure is not limited to such an aspect, and may be applied to heavy-duty pneumatic tires and non-pneumatic tires that are not filled with pressurized air.

As shown in FIG. 1 , the tread portion 2 of the present disclosure includes a first tread end T1, a second tread end T2, and a tire circumferentially continuous portion between the first tread end T1 and the second tread end T2. and a plurality of land portions 4 partitioned by the circumferential grooves 3 . As a desirable aspect, the tire 1 of this embodiment is configured as a so-called five-rib tire in which the tread portion 2 is configured by four circumferential grooves 3 and five land portions 4 .

For the tread portion 2 of the present embodiment, for example, the mounting direction to the vehicle is designated. Accordingly, the first tread end T1 is intended to be positioned on the outside of the vehicle when mounted on the vehicle. The second tread edge T2 is intended to be positioned on the inside of the vehicle when mounted on the vehicle. The mounting direction to the vehicle is indicated by letters or symbols on the side wall portion (not shown), for example. However, the tire 1 of the present disclosure is not limited to such an aspect, and may be one in which the mounting direction to the vehicle is not specified.

The first tread edge T1 and the second tread edge T2 are the edges of the contact surface when the tire 1 in the normal state is loaded with 70% of the normal load and the tread portion 2 is grounded on a flat surface with a camber angle of 0°. corresponds to

In the case of pneumatic tires that meet various standards, the term "normal condition" refers to a state in which the tire is mounted on a normal rim, inflated to a normal internal pressure, and unloaded. In the case of tires for which various standards are not defined or non-pneumatic tires, the normal condition means a standard usage condition according to the purpose of use of the tire, which is a condition in which the tire is not mounted on the vehicle and no load is applied. . In this specification, unless otherwise specified, the dimensions of each part of the tire are the values measured in the normal condition.

A "regular rim" is a rim defined for each tire in a standard system that includes standards on which tires are based. For ETRTO, 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.

In the case of pneumatic tires for which various standards have been established, the "regular load" is the load that each standard defines for each tire in the standard system including the standards that the tire is based on. "LOAD CAPACITY", the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "LOAD CAPACITY" for ETRTO. In addition, in the case of tires for which various standards have not been established, the "normal load" refers to the maximum load that can be applied when using the tire according to the above-mentioned standards.

The circumferential groove 3 includes a first shoulder circumferential groove 5 and a second shoulder circumferential groove 6, and a first crown circumferential groove 7 and a second crown circumferential groove 8 provided therebetween. The first shoulder circumferential groove 5 is provided closest to the first tread end T1 among the plurality of circumferential grooves 3 . The second shoulder circumferential groove 6 is provided closest to the second tread end T2 among the plurality of circumferential grooves 3 . The first crown circumferential groove 7 is provided between the first shoulder circumferential groove 5 and the tire equator C. As shown in FIG. The second crown circumferential groove 8 is provided between the second shoulder circumferential groove 6 and the tire equator C. As shown in FIG.

The axial distance L1 from the tire equator C to the center line of the first shoulder circumferential groove 5 or the second shoulder circumferential groove 6 is preferably 25% to 35% of the tread width TW, for example. A tire axial distance L2 from the tire equator C to the groove center line of the first crown circumferential groove 7 or the second crown circumferential groove 8 is preferably 5% to 15% of the tread width TW, for example. The tread width TW is the distance in the tire axial direction from the first tread end T1 to the second tread end T2 in the normal state.

In this embodiment, the second shoulder circumferential groove 6, the first crown circumferential groove 7, and the second crown circumferential groove 8 extend linearly or parallel to the tire circumferential direction. On the other hand, the groove edge of the first shoulder circumferential groove 5 on the tire equator C side extends in a zigzag shape. However, each circumferential groove 3 is not limited to such a shape.

It is desirable that the groove width W1 of each circumferential groove 3 is at least 3 mm or more. Further, it is desirable that the groove width W1 of each circumferential groove 3 is, for example, 3.0% to 7.0% of the tread width TW. The depth of each circumferential groove 3 is, for example, 5 to 10 mm in the case of a pneumatic tire for passenger cars.

The five land portions 4 of the present disclosure include a crown land portion 15 provided between the first tread edge T1 and the second tread edge T2. The crown land portion 15 of this embodiment is divided between the first crown circumferential groove 7 and the second crown circumferential groove 8 . Thereby, the crown land portion 15 is provided on the tire equator C. As shown in FIG. Also, the land portion 4 of the present embodiment includes a first middle land portion 13 , a second middle land portion 14 , a first shoulder land portion 11 and a second shoulder land portion 12 . The first middle land portion 13 is divided between the first shoulder circumferential groove 5 and the first crown circumferential groove 7 . The second middle land portion 14 is divided between the second shoulder circumferential groove 6 and the second crown circumferential groove 8 . The first shoulder land portion 11 includes a first tread end T1 and is divided axially outward of the first shoulder circumferential groove 5 . The second shoulder land portion 12 includes a second tread end T2 and is divided axially outward of the second shoulder circumferential groove 6 .

FIG. 2 shows an enlarged view of the crown land portion 15 of FIG. As shown in FIG. 2, the crown land portion 15 includes a first longitudinal edge 15a extending in the tire circumferential direction on the first tread end T1 side and a second longitudinal edge 15b extending in the tire circumferential direction on the second tread end T2 side. and a tread 15s between the first longitudinal edge 15a and the second longitudinal edge 15b. In the present disclosure, the crown land portion 15 is provided with a plurality of first crown sipes 41 and a plurality of second crown sipes 42 . Further, the crown land portion 15 of the present embodiment is provided with a plurality of third crown sipes 43 and a plurality of fourth crown sipes 44 .

As used herein, the term "sipe" means a small width incision in which the width between two sipe walls in the sipe body is 1.5 mm or less. Further, the sipe body portion means a portion in which two sipe walls extend substantially parallel to each other in the tire radial direction. "Substantially parallel" means that the angle between two sipe walls is 10° or less. The sipes may include chamfers, as described below. The sipe may also have a so-called flask bottom with an increased width at the bottom.

FIG. 3 shows an enlarged view of the first crown sipe 41, the second crown sipe 42, the third crown sipe 43 and the fourth crown sipe 44. As shown in FIG. As shown in FIG. 3, in the present disclosure, first crown sipe 41 extends from first longitudinal edge 15a and has a discontinuity 41a in tread 15s. A second crown sipe 42 extends from the second longitudinal edge 15b and has a discontinuity 42a in the tread surface 15s.

Each first crown sipe 41 and each second crown sipe 42 are inclined in the same direction with respect to the tire axial direction. The angle of these sipes with respect to the tire axial direction is, for example, 25-35°.

In the present disclosure, the distance L4 in the tire circumferential direction between the outer end 41b of the first crown sipe 41 on the side of the first longitudinal edge 15a and the outer end 42b of the second crown sipe 42 on the side of the second longitudinal edge 15b is It is 10% or less of one pitch length P1 (shown in FIG. 2) of the first crown sipe 41 in the tire circumferential direction. By adopting the above configuration, the tire of the present disclosure exhibits excellent wet performance while maintaining steering stability on dry road surfaces (hereinafter sometimes simply referred to as "steering stability"). can be done. The mechanism is as follows.

Since the first crown sipe 41 and the second crown sipe 42 have discontinuous ends in the crown land portion 15, the rigidity of the crown land portion 15 can be maintained and frictional force can be provided during wet running. In addition, since the first crown sipe 41 and the second crown sipe 42 are inclined in the same direction with respect to the tire axial direction, they cooperate to provide a frictional force also in the tire axial direction, thereby improving wet performance. Further improve.

In addition, since the distance between the outer end 41b of the first crown sipe 41 and the outer end 42b of the second crown sipe 42 is 10% or less of the one pitch length P1, during wet running, The water displaced by the sipes is easily guided to the outer end side of one of the sipes, thereby improving the wet performance. Due to such a mechanism, the tire 1 of the present disclosure can exhibit excellent wet performance while maintaining steering stability.

A more detailed configuration of the present embodiment will be described below. Each configuration described below represents a specific aspect of the present embodiment. Therefore, it goes without saying that the present disclosure can exhibit the above effects even if it does not have the configuration described below. Further, even if any one of the configurations described below is applied alone to the tire of the present disclosure having the features described above, an improvement in performance according to each configuration can be expected. Furthermore, when some of the respective configurations described below are applied in combination, it is possible to expect a combined improvement in performance according to each configuration.

The axial length L6 of the first crown sipe 41 is, for example, 40% to 60% of the axial width W5 of the tread surface 15s of the crown land portion 15 (shown in FIG. 2 and the same applies hereinafter). %. In addition, in this specification, the length of a sipe shall be measured by the centerline of a sipe.

The second crown sipe 42 preferably crosses the center position of the tread surface 15s of the crown land portion 15 in the tire axial direction. The discontinuous end 42a of the second crown sipe 42 is located closer to the first vertical edge 15a than the discontinuous end 41a of the first crown sipe 41 is. The axial length L7 of the second crown sipe 42 is preferably greater than the axial length L6 of the first crown sipe 41 . Specifically, the length L7 of the second crown sipe 42 is 65% to 85% of the width W5 of the tread surface 15s of the crown land portion 15. As shown in FIG. Such a second crown sipe 42 can improve performance on snow and wet performance while maintaining steering stability.

In this embodiment, the third crown sipe 43 extends from the first longitudinal edge 15a and has a discontinuity 43a in the tread 15s. The third crown sipe 43 has a shape different from that of the first crown sipe 41 in a tread plan view. A fourth crown sipe 44 also extends from the second longitudinal edge 15b and has a discontinuity 44a within the tread surface 15s. The fourth crown sipe 44 has a shape different from that of the second crown sipe 42 in a tread plan view. The third crown sipe 43 and the fourth crown sipe 44 are inclined in the same direction as the first crown sipe 41 and the second crown sipe 42 with respect to the tire axial direction. The angle of these sipes with respect to the tire axial direction is, for example, 25 to 35°.

A distance L5 in the tire circumferential direction between the outer end 43b of the third crown sipe 43 on the side of the first vertical edge 15a and the outer end 44b of the fourth crown sipe 44 on the side of the second vertical edge 15b is equal to the distance L5 of the third crown sipe. It is desirable to be 10% or less of one pitch length P2 (shown in FIG. 2) of 43 in the tire circumferential direction. This further improves the wet performance.

The axial length L8 of the third crown sipe 43 is smaller than the length L7 of the second crown sipe 42 and smaller than the length L6 of the first crown sipe 41 . Further, the interrupted end 43a of the third crown sipe 43 is located closer to the first vertical edge 15a than the interrupted end 44a of the fourth crown sipe 44 is. In a more desirable aspect, the interrupted end 43a of the third crown sipe 43 is located closer to the second vertical edge 15b than the interrupted end 42a of the second crown sipe 42 is. The length L8 of the third crown sipe 43 is 25% to 45% of the width W5 of the tread surface 15s of the crown land portion 15. As shown in FIG. Such a third crown sipe 43 serves to improve steering stability, snow performance and wet performance in a well-balanced manner.

From a similar point of view, the axial length L9 of the fourth crown sipe 44 is, for example, smaller than the length L7 of the second crown sipe 42 and longer than the length L6 of the first crown sipe 41. small. Specifically, the length L9 of the fourth crown sipe 44 is 25% to 45% of the width W5 of the tread surface 15s of the crown land portion 15. As shown in FIG.

FIG. 4 shows a cross-sectional view taken along line EE of FIG. 2 as a diagram showing the cross-sectional shape of the above-described sipe. As shown in FIG. 4 , the first crown sipe 41 , the second crown sipe 42 , the third crown sipe 43 and the fourth crown sipe 44 are each opened at the tread surface 15 s via the chamfered portion 45 . The chamfered portion 45 includes an inclined surface 45s cut between the tread surface 15s and the sipe wall. 45 s of inclined surfaces of this embodiment are slightly curved in the direction which becomes convex to the tire radial direction outer side. The inclined surface 45s may be planar, for example. Such a chamfered portion 45 equalizes ground contact pressure acting on the tread surface 15s of the crown land portion 15, thereby improving steering stability and uneven wear resistance.

As shown in FIG. 2, each of the first crown sipe 41 and the second crown sipe 42 preferably has a chamfered portion 45 interposed between the first crown sipe 41 and the second crown sipe 42 so that the entire length thereof is open at the tread surface. Moreover, it is desirable that the chamfer width W6 of the chamfered portion 45 of the first crown sipe 41 and the chamfered width W7 of the chamfered portion 45 of the second crown sipe 42 are constant in the sipe longitudinal direction. The chamfered width W7 of the chamfered portion 45 of the second crown sipe 42 is 80% to 120% of the chamfered width W6 of the chamfered portion 45 of the first crown sipe 41, and in this embodiment, these are substantially the same. be done. This suppresses uneven wear around these sipes.

It is desirable that the chamfered width of the chamfered portion 45 of the third crown sipe 43 continuously decreases from the first longitudinal edge 15a toward the interrupted end 43a. It is desirable that the chamfered width of the chamfered portion 45 of the fourth crown sipe 44 continuously decreases from the second longitudinal edge 15b toward the interrupted end 44a. As a result, a sufficient contact area can be secured in the central portion of the crown land portion 15, and steering stability can be reliably maintained. In the third crown sipe 43 of the present embodiment, the chamfered portion has substantially disappeared at the interrupted end 43a, but the chamfered portion 45 remains at the interrupted end 43a. Anything you do is fine. The fourth crown sipe 44 is also the same.

The maximum chamfered width W8 of the chamfered portion 45 of the third crown sipe 43 is smaller than the chamfered width W6 of the chamfered portion 45 of the first crown sipe 41 . Specifically, the chamfered width W8 of the third crown sipe 43 is 75% to 90% of the chamfered width W6 of the first crown sipe 41. As shown in FIG. Similarly, the maximum chamfer width W9 of the chamfered portion 45 of the fourth crown sipe 44 is smaller than the chamfered width W7 of the chamfered portion 45 of the second crown sipe 42 . Specifically, the chamfered width W9 of the fourth crown sipe 44 is 75% to 90% of the chamfered width W7 of the second crown sipe . The third crown sipe 43 and the fourth crown sipe 44 as described above serve to improve steering stability and on-snow performance in a well-balanced manner.

FIG. 5 shows an enlarged view of the first middle land portion 13. As shown in FIG. As shown in FIG. 5, the first middle land portion 13 includes a first longitudinal edge 13a extending in the tire circumferential direction on the first tread end T1 side and a second longitudinal edge 13a extending in the tire circumferential direction on the second tread end T2 side. It includes an edge 13b and a tread surface 13s between the first longitudinal edge 13a and the second longitudinal edge 13b. A plurality of middle lateral grooves 20 are provided in the first middle land portion 13 . The middle lateral groove 20 is, for example, inclined in the same direction as the first crown sipe 41 (shown in FIG. 2) with respect to the tire axial direction.

An enlarged view of the two middle lateral grooves 20 is shown in FIG. 6 is an enlarged view of a first middle lateral groove 21 and a second middle lateral groove 22, which will be described later. At least one of the middle lateral grooves 20 includes a first groove portion 26 and a second groove portion 27, as shown in FIG. The first groove portion 26 extends axially from the first longitudinal edge 13a. The second groove portion 27 extends axially from the second longitudinal edge 13b.

In the present embodiment, the first groove portion 26 and the second groove portion 27 are displaced in the tire circumferential direction, so that the gap between the groove edge 26e of the first groove portion 26 and the groove edge 27e of the second groove portion 27 is the tire A longitudinal groove edge 28e extending in the circumferential direction is formed. Also, the maximum depth of the first groove portion 26 is different from the maximum depth of the second groove portion 27 . The middle lateral grooves 20 provide a large reaction force (hereinafter, such reaction force may be referred to as "snow column shear force") by strongly compressing the snow inside and shearing it when traveling on snow. do. In addition, since the maximum depth of the first groove portion 26 and the second groove portion 27 are different, the groove portion with the smaller depth maintains the rigidity of the first middle land portion 13, thereby maintaining steering stability. Grooves with a larger width can provide a larger snow shear force, improving on-snow performance.

The above-mentioned flute edges 28e also provide frictional forces in the axial direction of the tire, helping to improve turning performance on snow. Furthermore, by combining the longitudinal groove edge 28e with the above-described first groove portion 26 and second groove portion 27, the snow that has entered the deeper groove portion is easily compacted in the axial direction of the tire. A snow column shear force is exerted.

As shown in FIGS. 5 and 6, in this embodiment each middle lateral groove 20 has the features described above. Further, in a tread plan view, the first groove portion 26 and the second groove portion 27 extend in the tire axial direction with a constant groove width W3 (shown in FIG. 5). The groove width W3 of the first groove portion 26 and the second groove portion 27 is, for example, 15% to 25% of the width W2 of the contact surface of the first middle land portion 13 (shown in FIG. 5). The angle of the first groove portion 26 and the second groove portion 27 with respect to the tire axial direction is, for example, 25 to 35 degrees.

The middle lateral grooves 20 include a plurality of first middle lateral grooves 21 and a plurality of second middle lateral grooves 22 having different depth distributions. For example, the first middle lateral grooves 21 and the second middle lateral grooves 22 are provided alternately in the tire circumferential direction.

FIG. 7 shows a cross-sectional view taken along line AA of FIG. FIG. 7 is a cross-sectional view of the first middle lateral groove 21 along the groove longitudinal direction. FIG. 8 shows a cross-sectional view taken along line BB of FIG. FIG. 8 is a cross-sectional view of the second middle lateral groove 22 along the groove longitudinal direction. As shown in FIGS. 7 and 8, the first groove portion 26 and the second groove portion 27 of the first middle lateral groove 21 and the first groove portion 26 and the second groove portion 27 of the second middle lateral groove 22 of this embodiment are Each extends in the longitudinal direction of the groove at a constant depth.

As shown in FIG. 7 , in the first middle lateral groove 21 , the maximum depth d1 of the first groove portion 26 is smaller than the maximum depth d2 of the second groove portion 27 . In the first middle lateral groove 21, the depth d2 of the second groove portion 27 is 60% to 80% of the depth dc of the first crown circumferential groove 7, for example. Further, in the first middle lateral groove 21, the depth d1 of the first groove portion 26 is 40% to 60% of the depth dc of the first crown circumferential groove 7. As shown in FIG. Accordingly, the depth d1 of the first groove portion 26 is preferably 60% to 70% of the depth d2 of the second groove portion 27. FIG.

As shown in FIG. 8 , the second middle lateral grooves 22 have substantially the inverted shape of the first middle lateral grooves 21 . That is, in the second middle lateral groove 22 , the maximum depth d1 of the first groove portion 26 is greater than the maximum depth d2 of the second groove portion 27 . In the second middle lateral groove 22, the depth d1 of the first groove portion 26 is 60% to 80% of the depth dc of the first crown circumferential groove 7, for example. In the second middle lateral groove 22, the depth d2 of the second groove portion 27 is 40% to 60% of the depth dc of the first crown circumferential groove 7. As shown in FIG. Therefore, the depth d2 of the second groove 27 is preferably 60% to 70% of the depth d1 of the first groove 26. FIG.

In this embodiment, the first middle lateral grooves 21 and the second middle lateral grooves 22 are provided alternately in the tire circumferential direction, thereby improving steering stability and on-snow performance in a well-balanced manner.

FIG. 9 shows a cross-sectional view taken along line CC of FIG. FIG. 9 is a cross-sectional view of the second groove portion 27 of the first middle lateral groove 21 or the first groove portion 26 of the second middle lateral groove 22 (hereinafter collectively referred to as deep groove portion 37). . FIG. 10 shows a cross-sectional view taken along line DD of FIG. FIG. 10 is a cross-sectional view of the first groove portion 26 of the first middle lateral groove 21 or the second groove portion 27 of the second middle lateral groove 22 (hereinafter collectively referred to as shallow groove portion 36 in some cases). .

As shown in FIGS. 9 and 10, the deep groove portion 37 and the shallow groove portion 36 are preferably opened through the chamfered portion 25, respectively. The chamfered portion 25 includes an inclined surface 25s cut between the tread surface of the land portion and the groove wall. 25 s of inclined surfaces of this embodiment are slightly curved in the direction which becomes convex to the tire radial direction outside. The inclined surface 25s may be planar, for example. Such a chamfered portion 25 serves to equalize ground contact pressure acting on the tread surface 13s and improve uneven wear resistance performance.

As shown in FIG. 9, the deep groove portion 37 includes, for example, a flat groove bottom portion 37d. On the other hand, as shown in FIG. 10, the shallow groove portion 36 has a groove bottom sipe 38 that opens at a groove bottom portion 36d and extends in the tire radial direction. Such a groove bottom sipe 38 facilitates opening of the shallow groove portion 36 appropriately and serves to enhance performance on snow. The depth d1 of the first groove portion 26 of the first middle lateral groove 21 and the depth d2 of the second groove portion 27 of the second middle lateral groove 22 are depths not including the groove bottom sipe 38. . 7 and 8, the groove bottom sipe 38 is omitted. In a desirable aspect, the total depth from the tread surface of the land portion to the bottom of the groove bottom sipe 38 is also smaller than the depth of the deep groove portion 37 . As a result, steering stability and on-snow performance are improved in a well-balanced manner.

As shown in FIG. 6, in this embodiment, each of the groove edges on both sides of one middle lateral groove 20 includes a vertical groove edge 28e. These two longitudinal groove edges 28e are arranged, for example, in the central area when the tread surface 13s of the first middle land portion 13 is divided into three equal parts in the axial direction of the tire. As a result, the two longitudinal groove edges 28e are arranged so as to sandwich the center position of the tread surface 13s of the first middle land portion 13 in the tire axial direction. Also, the two flute edges 28e each extend along the tire circumferential direction, and in a preferred embodiment they extend parallel to each other. The angle of the longitudinal groove edge 28e with respect to the tire circumferential direction is, for example, 10° or less, preferably 5° or less. It is desirable that the length L3 of the longitudinal groove edge 28e in the tire circumferential direction is smaller than the maximum groove width of the first groove portion 26 and the second groove portion 27 . Specifically, the length L3 is 75% to 95% of the groove width. Such vertical groove edges 28e can improve turning performance during driving on snow while suppressing uneven wear.

Middle lateral groove 20 includes vertical groove portion 28 provided between first groove portion 26 and second groove portion 27 . In this embodiment, for example, the region between one vertical groove edge 28e and its imaginary extension line extending in the length direction and the other vertical groove edge 28e and its imaginary extension line extending in its length direction is the vertical groove portion 28.

As shown in FIGS. 7 and 8, the maximum depth d3 of the vertical groove 28 is smaller than the maximum depth d1 of the first groove 26 and the maximum depth d2 of the second groove 27. As shown in FIGS. Specifically, the maximum depth d3 of the vertical groove portion 28 is 20% to 30% of the depth dc of the first crown circumferential groove 7 . Such vertical grooves 28 increase the rigidity of the central portion of the first middle land portion 13 and improve uneven wear resistance.

As shown in FIG. 5, the first middle land portion 13 is preferably provided with at least one vertical sipe 30 extending in the tire circumferential direction. A plurality of vertical sipes 30 are spaced apart in the tire circumferential direction in the first middle land portion 13 of the present embodiment. Further, the vertical sipe 30 of this embodiment extends from the tread surface 13s of the first middle land portion 13 to the bottom with a constant width. Such vertical sipes 30 can provide a large frictional force in the axial direction of the tire during wet driving or driving on snow.

The vertical sipe 30 is desirably arranged, for example, in the central area when the tread surface 13s of the first middle land portion 13 is divided into three equal parts in the axial direction of the tire. The angle of the vertical sipe 30 with respect to the tire circumferential direction is, for example, 10° or less, preferably 5° or less. Such vertical sipes 30 can provide a large frictional force in the axial direction of the tire when traveling on snow.

The vertical sipes 30 cross the middle lateral grooves 20 in the tire circumferential direction, for example. In a preferred embodiment, the vertical sipes 30 are arranged across the first middle lateral grooves 21 and do not communicate with the second middle lateral grooves 22 . More specifically, the vertical sipe 30 crosses the vertical groove portion 28 of the first middle lateral groove 21 . As a result, a vertical sipe 30 is formed as a groove bottom sipe at the groove bottom of the vertical groove 28 . On the other hand, the second middle lateral groove 22 does not have such a structure. As a result, steering stability, performance on snow, and resistance to uneven wear are improved in a well-balanced manner.

As shown in FIG. 5 , the first middle land portion 13 is provided with a plurality of first middle sipes 31 and a plurality of second middle sipes 32 . A first middle sipe 31 extends from the first longitudinal edge 13 a and communicates with the longitudinal sipe 30 . A second middle sipe 32 extends from the second longitudinal edge 13 b and communicates with the longitudinal sipe 30 . In a desirable aspect, the end of the first middle sipe 31 within the tread surface 13s communicates with the end of the vertical sipe 30 on one side in the tire circumferential direction. The end of the second middle sipe 32 within the tread surface 13s communicates with the end of the vertical sipe 30 on the other side in the tire circumferential direction. The first middle sipe 31 and the second middle sipe 32 cooperate with the vertical sipe 30 to provide frictional force in multiple directions, further improving on-snow performance.

The first middle sipe 31 and the second middle sipe 32 are, for example, inclined in the same direction as the middle lateral groove 20 with respect to the tire axial direction. The angle of these sipes with respect to the tire axial direction is, for example, 25-35°. In a preferred embodiment, the first middle sipe 31 and the vertical sipe 30 communicate with each other so that the corners between them form an acute angle. Similarly, the second middle sipe 32 and the vertical sipe 30 communicate with each other so that the corners between them form an acute angle. This makes it easier for the corners to bite into the road surface when traveling on snow, thereby exhibiting excellent on-snow performance.

The first middle sipe 31 and the second middle sipe 32 are opened at the tread surface 13s via the chamfered portion 35, respectively. The configuration of the crown sipe chamfer 45 (shown in FIG. 4) can be applied to these sipe chamfers 35, and the description thereof is omitted here. Such a chamfered portion 35 serves to equalize ground contact pressure acting on the tread surface 13s and improve steering stability and uneven wear resistance performance.

As shown in FIG. 5, it is desirable that the chamfered width of the chamfered portion 35 of the first middle sipe 31 decreases toward the vertical sipe 30 side. Similarly, it is desirable that the chamfered width of the chamfered portion 35 of the second middle sipe 32 decreases toward the vertical sipe 30 side. As a result, the ground contact area of the central portion of the first middle land portion 13 is ensured, and steering stability can be maintained. The chamfer width is the opening width of the chamfer in the tread plan view. Further, the opening width means the width in the direction perpendicular to the sipe longitudinal direction.

FIG. 11 shows an enlarged view of the second middle land portion 14. As shown in FIG. As shown in FIG. 11 , third middle lateral grooves 23 and fourth middle lateral grooves 24 are alternately provided in the second middle land portion 14 in the tire circumferential direction. The third middle lateral groove 23 and the fourth middle lateral groove 24 have a common shape in a tread plan view, and completely cross the second middle land portion 14 in the tire axial direction. The third middle lateral groove 23 and the fourth middle lateral groove 24 are inclined in the same direction as the middle lateral groove 20 (shown in FIG. 2) with respect to the tire axial direction. The angle of the third middle lateral groove 23 and the fourth middle lateral groove 24 with respect to the tire axial direction is smaller than the angle of the middle lateral groove 20 (shown in FIG. 2) with respect to the tire axial direction. less than the angle of each sipe with respect to the axial direction of the tire. Specifically, the angle of the third middle lateral groove 23 and the fourth middle lateral groove 24 with respect to the tire axial direction is, for example, 10 to 20 degrees. On the other hand, the third middle lateral groove 23 and the fourth middle lateral groove 24 are different in internal configuration.

FIG. 12 shows a cross-sectional view taken along line FF of FIG. As shown in FIG. 12, the third middle lateral groove 23 has a shallow groove portion 46 on the second crown circumferential groove 8 side and a deep groove portion 47 on the second shoulder circumferential groove 6 side. FIG. 13 shows a cross-sectional view taken along line GG of FIG. As shown in FIG. 13 , the fourth middle lateral groove 24 has substantially the reverse shape of the third middle lateral groove 23 . That is, the fourth middle lateral groove 24 has a deep groove portion 47 on the second crown circumferential groove 8 side and a shallow groove portion 46 on the second shoulder circumferential groove 6 side. In this embodiment, the third middle lateral grooves 23 and the fourth middle lateral grooves 24 are alternately provided in the tire circumferential direction, thereby improving uneven wear resistance and steering stability.

For the shallow groove portions 46 of the third middle lateral groove 23 and the fourth middle lateral groove 24, the structure of the shallow groove portion 36 (shown in FIG. 10) of the middle lateral groove 20 described above can be applied. Similarly, the configuration of the deep groove portion 37 (shown in FIG. 9) of the middle lateral groove 20 described above can be applied to the deep groove portions 47 of the third middle lateral groove 23 and the fourth middle lateral groove 24 .

As shown in FIG. 11 , the second middle land portion 14 is provided with a plurality of middle sipe groups 55 in which a plurality of bent sipes 56 are arranged in the tire axial direction in the tire circumferential direction. In this embodiment, the middle sipe group 55 is configured by arranging a plurality of bent sipes 56 so as to overlap each other in the tire axial direction. The bent sipe 56 includes a portion that protrudes on one side or the other side in the tire circumferential direction. Since the middle sipe group 55 is difficult to open during braking and driving, snow and ice are less likely to clog inside during driving on snow, and excellent on-snow performance can be maintained.

The present disclosure is not limited to the second middle land portion 14 shown in FIG. 11 . FIG. 14 shows an enlarged view of the second middle land portion 14 in another embodiment of the present disclosure. As shown in FIG. 14, the second middle land portion 14 of this embodiment includes a plurality of third middle sipes 33 and a plurality of fourth middle sipes 34 in addition to the third middle lateral grooves 23 and the fourth middle lateral grooves 24 described above. is provided. The third middle sipe 33 extends from the second crown circumferential groove 8 and is discontinued within the tread surface of the second middle land portion 14 . The fourth middle sipe 34 extends from the second shoulder circumferential groove 6 and is discontinued within the tread surface. The third middle sipe 33 and the fourth middle sipe 34 are, for example, inclined in the same direction as the third middle lateral groove 23 and the fourth middle lateral groove 24 with respect to the tire axial direction. The angle of these sipes with respect to the tire axial direction is, for example, 10-20°. The configuration of the first middle sipe 31 or the second middle sipe 32 described above can be applied to the third middle sipe 33 and the fourth middle sipe 34 .

In the second middle land portion 14 of still another embodiment, for example, the above-described middle sipe group 55 (shown in FIG. 11) is placed between the third middle lateral groove 23 and the fourth middle lateral groove 24 adjacent in the tire circumferential direction. , the third middle sipe 33 and the fourth middle sipe 34 shown in FIG. 14 may be arranged (not shown). Such an arrangement of sipes helps to further improve on-snow performance.

As shown in FIG. 1 , the first shoulder land portion 11 is provided with a plurality of first shoulder lateral grooves 51 and first shoulder sipes 52 . The first shoulder lateral grooves 51 and the first shoulder sipes 52, for example, extend from the first shoulder circumferential grooves 5 to at least the first tread edge T1. The second shoulder land portion 12 is also provided with a shoulder sipe group 60 in which a plurality of second shoulder lateral grooves 53 and a plurality of bent sipes 61 are arranged in the tire axial direction. The shoulder sipe group 60 has substantially the same configuration as the middle sipe group 55 described above. These lateral grooves and sipes help further improve on-snow performance.

Although the tire according to one embodiment of the present disclosure has been described in detail above, the present disclosure is not limited to the above-described specific embodiments, and can be implemented with various modifications.

As a comparative example and Examples 1 and 2, pneumatic tires of size 245/40ZR18 were prototyped. The tire of Example 1 has a crown land portion 15 shown in FIG. The crown land portion 15 shown in FIG. 15 is obtained by extracting the features of the present disclosure. is about 4% of one pitch length of the first crown sipe in the tire circumferential direction. Also, the tire of Example 2 has the crown land portion 15 shown in FIG. 2, and the distance is approximately 4% of the length of one pitch.

On the other hand, the tire of the comparative example has a crown land portion a shown in FIG. In this crown land portion a, the distance in the tire circumferential direction between the outer end of the first crown sipe b and the outer end of the second crown sipe c is the length of one pitch length P1 of the first crown sipe b in the tire circumferential direction. It is about 27%. The crown land portion of the comparative example is substantially the same as the crown land portion 15 of Example 1, except for the matters described above. Moreover, Comparative Example and Examples 1 and 2 have the basic pattern shown in FIG.

The comparative example and Examples 1 and 2 were tested for steering stability and wet performance on a dry road surface. Common specifications and test methods for each test tire are as follows.
Mounting rim: 18 x 8.5J
Tire pressure: 240kPa for all wheels
Test vehicle: 2000cc displacement, rear-wheel drive Tire mounting position: All wheels

<Driving stability on dry road surface>
The steering stability of the test vehicle was evaluated by the driver's sensory perception when the test vehicle was driven on a dry road surface. The results are scored with the steering stability of the comparative example being 100, and the larger the numerical value, the better the steering stability.

<Wet Performance>
The wet performance when the test vehicle was run on a wet road surface was evaluated by the driver's senses. The results are scored with the wet performance of the comparative example being 100, and the larger the number, the better the wet performance.
The results of the tests are shown in Table 1.

As a result of the test, it was confirmed that Example 1 exhibited excellent wet performance while maintaining steering stability on dry road surfaces. In addition, it was confirmed that the performance of Example 2 was further improved as compared with Example 1.

[Appendix]
The present disclosure includes the following aspects.

[Present Disclosure 1]
A tire having a tread portion,
the tread portion includes a first tread edge, a second tread edge, and a crown land portion provided between the first tread edge and the second tread edge;
The crown land portion includes a first longitudinal edge extending in the tire circumferential direction on the first tread end side, a second longitudinal edge extending in the tire circumferential direction on the second tread end side, and the first longitudinal edge and the second longitudinal edge. a tread between two longitudinal edges;
The crown land portion includes a plurality of first crown sipes extending from the first longitudinal edge and having discontinuities within the tread surface, and a plurality of first crown sipes extending from the second longitudinal edge and having discontinuities within the tread surface. a plurality of second crown sipes having
each of the first crown sipes and each of the second crown sipes are inclined in the same direction with respect to the axial direction of the tire;
The distance in the tire circumferential direction between the outer end of the first crown sipe on the side of the first vertical edge and the outer end of the second crown sipe on the side of the second vertical edge is the tire 10% or less of the length of one pitch in the circumferential direction,
tire.
[Disclosure 2]
The tire according to the present disclosure 1, wherein the interrupted end of the second crown sipe is located closer to the first longitudinal edge than the interrupted end of the first crown sipe.
[Disclosure 3]
3. The tire according to the present disclosure 1 or 2, wherein the axial length of the second crown sipe is greater than the axial length of the first crown sipe.
[Disclosure 4]
4. The tire according to any one of the present disclosures 1 to 3, wherein each of the first crown sipe and the second crown sipe is open at the tread surface through a chamfered portion in the entire length direction thereof.
[Disclosure 5]
The crown land portion includes a plurality of third crown sipes extending from the first longitudinal edge and having discontinuities within the tread surface, and a plurality of third crown sipes extending from the second longitudinal edge and having discontinuities within the tread surface. a plurality of fourth crown sipes having
In a tread plan view, each of the third crown sipes and each of the fourth crown sipes has a shape different from that of the first crown sipe and the second crown sipe,
The distance in the tire circumferential direction between the outer end of the third crown sipe on the side of the first vertical edge and the outer end of the fourth crown sipe on the side of the second vertical edge is the tire 5. A tire according to any one of the present disclosures 1 to 4, which is 10% or less of one pitch length in the circumferential direction.
[Disclosure 6]
6. The tire according to the present disclosure 5, wherein the axial length of the third crown sipe is smaller than the axial length of the first crown sipe.
[Present Disclosure 7]
7. The tire according to 5 or 6 of the present disclosure, wherein the axial length of the fourth crown sipe is smaller than the axial length of the second crown sipe.
[Disclosure 8]
8. Any one of 5 to 7 of the present disclosure, wherein the third crown sipe and the fourth crown sipe are inclined in the same direction as the first crown sipe and the second crown sipe with respect to the tire axial direction, respectively. Tires listed.
[Disclosure 9]
9. The tire according to any one of the present disclosure 5 to 8, wherein the discontinuous end of the third crown sipe is located closer to the first longitudinal edge than the discontinuous end of the fourth crown sipe.
[Disclosure 10]
10. The tire according to any one of present disclosures 5 to 9, wherein the third crown sipe and the fourth crown sipe are each open at the tread surface via a chamfer.
[Present Disclosure 11]
The tread portion is specified in the mounting direction to the vehicle,
11. The tire according to any one of the present disclosures 1 to 10, wherein the first tread end is positioned on the vehicle outer side when mounted on the vehicle.

2 tread portion 15 crown land portion 15a first longitudinal edge 15b second longitudinal edge 15s tread surface 41 first crown sipe 41a interrupted edge 41b outer edge 42 second crown sipe 42a interrupted edge 42b outer edge T1 first tread edge T2 second tread end

Claims (11)

A tire having a tread portion,
the tread portion includes a first tread edge, a second tread edge, and a crown land portion provided between the first tread edge and the second tread edge;
The crown land portion includes a first longitudinal edge extending in the tire circumferential direction on the first tread end side, a second longitudinal edge extending in the tire circumferential direction on the second tread end side, and the first longitudinal edge and the second longitudinal edge. a tread between two longitudinal edges;
The crown land portion includes a plurality of first crown sipes extending from the first longitudinal edge and having discontinuities within the tread surface, and a plurality of first crown sipes extending from the second longitudinal edge and having discontinuities within the tread surface. a plurality of second crown sipes having
each of the first crown sipes and each of the second crown sipes are inclined in the same direction with respect to the axial direction of the tire;
The distance in the tire circumferential direction between the outer end of the first crown sipe on the side of the first vertical edge and the outer end of the second crown sipe on the side of the second vertical edge is the tire 10% or less of the length of one pitch in the circumferential direction,
tire. The tire according to claim 1, wherein said interrupted end of said second crown sipe is located closer to said first longitudinal edge than said interrupted end of said first crown sipe. The tire according to claim 1 or 2, wherein the axial length of the second crown sipe is greater than the axial length of the first crown sipe. The tire according to any one of claims 1 to 3, wherein each of the first crown sipe and the second crown sipe is open at the tread surface via a chamfered portion in the entire length direction. The crown land portion includes a plurality of third crown sipes extending from the first longitudinal edge and having discontinuities within the tread surface, and a plurality of third crown sipes extending from the second longitudinal edge and having discontinuities within the tread surface. a plurality of fourth crown sipes having
In a tread plan view, each of the third crown sipes and each of the fourth crown sipes has a shape different from that of the first crown sipe and the second crown sipe,
The distance in the tire circumferential direction between the outer end of the third crown sipe on the side of the first vertical edge and the outer end of the fourth crown sipe on the side of the second vertical edge is the tire 5. The tire according to any one of claims 1 to 4, which is 10% or less of the length of one pitch in the circumferential direction. The tire according to claim 5, wherein the axial length of the third crown sipe is smaller than the axial length of the first crown sipe. The tire according to claim 5 or 6, wherein the axial length of the fourth crown sipe is smaller than the axial length of the second crown sipe. 8. The third crown sipe and the fourth crown sipe according to any one of claims 5 to 7, wherein the third crown sipe and the fourth crown sipe are inclined in the same direction as the first crown sipe and the second crown sipe with respect to the tire axial direction. Tires as specified in paragraph. The tire according to any one of claims 5 to 8, wherein the interrupted end of the third crown sipe is located closer to the first longitudinal edge than the interrupted end of the fourth crown sipe. The tire according to any one of claims 5 to 9, wherein each of said third crown sipe and said fourth crown sipe opens at said tread surface via a chamfered portion. The tread portion is specified in the mounting direction to the vehicle,
11. The tire of any one of claims 1 to 10, wherein the first tread edge is located on the vehicle outer side when mounted on the vehicle.

Images