JP2019094004A - tire - Google Patents

Abstract

To provide a tire capable of achieving excellent steering stability while controlling uneven wear on a shoulder land part.SOLUTION: A tire comprises a tread part 2. The tread part 2 comprises: a first tread end Te1; a shoulder main groove 3A continuously extending in a tire circumferential direction between the first tread end Te1 and a tire equator C; and a shoulder land part 7A delimited between the first tread end Te1 and the shoulder main groove 3. The shoulder land part 7A is provided with shoulder sipes 10 each having a width less than 1.5 mm and extending in a tire axial direction. The shoulder sipe 10 comprises: a thready sipe 11; and wide sipe 12 having a width greater than that of the thready sipe 11. The wide sipes 12 are arranged on the shoulder main groove 3A side.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tire having a shoulder sipe.

  Patent Document 1 below proposes providing a shoulder sipe extending in the axial direction of the tire on the shoulder land portion in order to suppress uneven wear of the shoulder land portion of the pneumatic tire.

JP, 2016-13820, A

  However, in recent years, along with the enhancement of the performance of vehicles, not only the improvement of the wear resistance performance but also the improvement of the steering stability are also required. As a result of various experiments, the inventors have found that by improving the shoulder sipes, it is possible to improve the steering stability while maintaining the wear resistance of the shoulder land portion.

  The present invention has been made in view of the above-described actual situation, and its main object is to provide a tire capable of exhibiting excellent steering stability while suppressing uneven wear of a shoulder land portion.

  The present invention is a tire having a tread portion, wherein the tread portion includes a first tread end, a shoulder main groove continuously extending in a tire circumferential direction between the first tread end and a tire equator, and The shoulder land portion includes a shoulder land portion divided between the first tread end and the shoulder main groove, and the shoulder land portion is provided with a shoulder sipe extending in the tire axial direction with a width of less than 1.5 mm, The shoulder sipe includes a narrow sipe portion and a thick sipe portion whose width is larger than that of the thin sipe portion, and the thick sipe portion is disposed on the side of the shoulder main groove.

  In the tire according to the present invention, preferably, the thick sipe portion is in communication with the shoulder main groove.

  In the tire according to the present invention, it is desirable that the fine sipe portion is in communication with the first tread end.

  In the tire according to the present invention, it is preferable that a length in the tire axial direction of the fine sipe portion is larger than a length in the tire axial direction of the thick sipe portion.

  In the tire according to the present invention, the depth of the thick sipe portion is preferably larger than the depth of the fine sipe portion.

  In the tire according to the present invention, it is preferable that the tread portion has a direction of attachment to the vehicle specified, and the first tread end be located outside the vehicle when attached to the vehicle.

  In the tire according to the present invention, a plurality of the shoulder sipes are arranged at intervals in the circumferential direction of the tire, and extend inward in the axial direction of the tire from the first tread end between the shoulder sipes adjacent in the circumferential direction of the tire. Preferably, a shoulder lug groove is disposed which terminates without communicating with the shoulder main groove.

  In the tire according to the present invention, it is preferable that an inner end in the tire axial direction of the shoulder lug groove be located axially outward of the outer end in the tire axial direction of the thick sipe portion.

  In the tire according to the present invention, the shoulder land portion is provided with a narrow groove portion having a groove width of 1.5 mm or more and a groove depth of 2.0 mm or less, and the thick sipe portion has a groove bottom of the thin groove portion. Preferably, the tire extends radially inward from the tire.

  In the tire according to the present invention, the narrow groove portion extends outward in the tire axial direction from the shoulder main groove, and terminates between an outer end in the tire axial direction of the thick sipe portion and the first tread end. Is desirable.

  In the tire according to the present invention, the narrow groove portion is chamfered between at least one groove wall and the tread contact surface so that the groove width gradually increases toward the shoulder main groove at the communication portion with the shoulder main groove. It is desirable to be done.

  The shoulder land portion of the tire of the present invention is provided with a shoulder sipe extending in the axial direction of the tire with a width of less than 1.5 mm. The shoulder sipe relieves the distortion at the time of contact with the shoulder land portion and suppresses its uneven wear.

  The shoulder sipe includes a fine sipe portion and a thick sipe portion having a larger width than the fine sipe portion. The thick sipe portion can reduce the rigidity of the land portion around it more than the fine sipe portion. For this reason, the land portion around the thick sipe portion can easily follow the road surface even in the initial state of turning, for example, in which the ground contact load is not sufficiently increased, and excellent initial responsiveness can be obtained. In particular, the thick sipe portion of the present invention is disposed on the side of the shoulder main groove. At the shoulder main groove side of the shoulder land portion, at the initial stage of turning, there is a tendency for a larger contact load to act than the tread end side. Therefore, by providing the thick sipe portion in this region, the initial responsiveness is remarkably improved.

  In addition, the land portion around the narrow sipe portion is disposed closer to the tread end than the thick sipe portion, and provides a higher rigidity than the land portion around the thick sipe portion. A large cornering force can be exerted in the middle stage of turning, which in turn can improve steering stability.

It is an expanded view of a tread part of a tire of one embodiment of the present invention. It is the sectional view on the AA line of FIG. It is an enlarged view of the outer side shoulder land part of FIG. (A) is the BB sectional drawing of FIG. 3, (b) is the CC sectional view shown in FIG. It is an enlarged view of the inside shoulder land part of FIG. It is the DD sectional view taken on the line of FIG. It is an enlarged view of the outer side crown land part of FIG. (A) is a cross-sectional view taken along the line E-E in FIG. 7, (b) is a cross-sectional view taken along the line F-F in FIG. 7, and (c) is a cross-sectional view taken along the line G-G in FIG. . It is an enlarged view of the inner crown land part of FIG. (A) is a cross-sectional view taken along the line HH in FIG. 9, (b) is a cross-sectional view taken along the line I-I in FIG. 9, and (c) is a cross-sectional view taken along the line JJ in FIG. . It is an expanded view of the tread part of the tire of other embodiment of this invention. It is an enlarged view of the outer side shoulder land part of comparative example 1. FIG. FIG. 16 is an enlarged view of an outer shoulder land portion of Comparative Example 2;

Hereinafter, an embodiment of the present invention will be described based on the drawings.
FIG. 1 is a developed view of a tread portion 2 of a tire 1 showing an embodiment of the present invention. The tire 1 of the present embodiment can be used, for example, in various tires such as pneumatic tires for passenger cars and heavy loads, and non-pneumatic tires in which the inside of the tire is not filled with pressurized air. The tire 1 of the present embodiment is suitably used, for example, as a pneumatic tire for a passenger car.

  As shown in FIG. 1, the tire 1 of the present embodiment has, for example, a tread portion 2 in which the direction of mounting on a vehicle is designated. However, the present invention is not limited to such an embodiment. The tread portion 2 has, for example, a first tread end Te1 located on the outer side of the vehicle when the tire 1 is mounted on the vehicle, and a second tread end Te2 located on the inner side of the vehicle when the vehicle is mounted. The direction of attachment to the vehicle is displayed, for example, in the side wall (not shown) as characters or symbols.

  In the case of a pneumatic tire, each tread end Te1 and Te2 is a contact position on the outermost side in the axial direction of the tire when a normal load is applied to the tire 1 in a normal state and the flat surface is grounded at a camber angle of 0 °. The normal state is a state in which the tire is rim-assembled on a normal rim, filled with a normal internal pressure, and unloaded. In the present specification, unless otherwise noted, the dimensions and the like of each part of the tire are values measured in the normal state.

  The “regular rim” is a rim that defines the standard for each tire in the standard system including the standard on which the tire is based, for example, “standard rim” for JATMA, “Design Rim” for ETRA, and “TRA” for TRA If it is, it is "Measuring Rim".

  The “normal internal pressure” is the air pressure specified by each standard in the standard system including the standard on which the tire is based, and in the case of JATMA, the “maximum air pressure”; in the case of TRA, the table “TIRE LOAD LIMITS AT The maximum value described in VARIOUS COLD INFlation PRESSURES, and in the case of ETRTO, it is “INFLATION PRESSURE”.

  "Normal load" is the load defined by each standard in the standard system including the standard on which the tire is based, and if it is JATMA, "maximum load capacity", if it is TRA, the table "TIRE LOAD LIMITS At the time of ETRTO, it is "LOAD CAPACITY".

  The tread portion 2 of the present embodiment is provided with, for example, a main groove continuously extending in the tire circumferential direction. The main groove is adjacent to the shoulder main groove 3 provided between, for example, the first tread end Te1 and the tire equator C, or between the second tread end Te2 and the tire equator C, and the shoulder main groove 3 And a crown main groove 4.

  The shoulder main groove 3 of the present embodiment is provided, for example, between an outer shoulder main groove 3A provided between the first tread end Te1 and the tire equator C, and between the second tread end Te2 and the tire equator C. And an inner shoulder main groove 3B.

  The shoulder main groove 3 desirably has a distance L1 from the tire equator C to the groove center line of 0.20 to 0.30 times the tread width TW, for example. The tread width TW is a distance in the tire axial direction from the first tread end Te1 to the second tread end Te2 in the normal state.

  For example, one crown main groove 4 is provided between two shoulder main grooves 3 and is provided on a tire equator C in the present embodiment. However, the present invention is not limited to such an aspect, and for example, two crown main grooves 4 may be provided so as to sandwich the tire equator C.

  The groove width W1a of the crown main groove 4 is desirably larger than, for example, the groove width W1b of the outer shoulder main groove 3A and the groove width W1c of the inner shoulder main groove 3B. Specifically, the groove width W1a of the crown main groove 4 is desirably 1.25 to 1.35 times the groove width W1b of the outer shoulder main groove 3A. This provides excellent wet performance.

  The groove width W1c of the inner shoulder main groove 3B is preferably, for example, larger than the groove width W1b of the outer shoulder main groove 3A. Specifically, the groove width W1c of the inner shoulder main groove 3B is desirably 1.20 to 1.28 times the groove width W1b of the outer shoulder main groove 3A.

  The groove width W1a of the crown main groove 4, the groove width W1b of the outer shoulder main groove 3A, and the groove width W1c of the inner shoulder main groove 3B are, for example, It is desirable that it is 4.0%-7.0% of tread width TW. In addition, when the dimension of a groove | channel is shown by this specification, the dimension which does not contain a chamfer is shown.

  FIG. 2 is a cross-sectional view taken along the line A-A of FIG. As shown in FIG. 2, the groove depth D1a of the crown main groove 4, the groove depth D1b of the outer shoulder main groove 3A, and the groove depth D1c of the inner shoulder main groove 3B are, for example, 6.0 to 12.0 mm. Is desirable.

  As shown in FIG. 1, the tread portion 2 of the present embodiment is divided into a shoulder land portion 7 and a crown land portion 8 by the above-described main groove. The shoulder land portion 7 is divided between the tread end and the shoulder main groove 3. The shoulder land portion 7 of the present embodiment includes, for example, an outer shoulder land portion 7A and an inner shoulder land portion 7B. The outer shoulder land portion 7A is divided between the first tread end Te1 and the outer shoulder main groove 3A. The inner shoulder land portion 7B is divided between the second tread end Te2 and the inner shoulder main groove 3B.

  The crown land portion 8 is divided between the two shoulder main grooves 3A and 3B. The crown land portion 8 includes, for example, an outer crown land portion 8A and an inner crown land portion 8B. The outer crown land portion 8A is divided between the outer shoulder main groove 3A and the crown main groove 4. The inner crown land portion 8 B is divided between the inner shoulder main groove 3 B and the crown main groove 4. However, the present invention is not limited to such an aspect, and for example, three crown land portions 8 may be divided between two shoulder main grooves 3.

  In FIG. 3, as an example of the shoulder land portion 7, an enlarged view of the outer shoulder land portion 7 </ b> A is shown. As shown in FIG. 3, the shoulder land portion 7 </ b> A is provided with a shoulder sipe 10 extending in the tire axial direction. In the present specification, “sipe” is a cut having a width of less than 1.5 mm. Further, in the present specification, a shoulder sipe provided in the outer shoulder land portion 7A may be referred to as an outer shoulder sipe. The shoulder sipe 10 relieves the strain at the time of contact with the shoulder land portion 7A and suppresses its uneven wear.

  The shoulder sipe 10 of the present embodiment extends from the shoulder main groove 3A to the first tread end Te1. However, the present invention is not limited to such an aspect, and one or both ends of the shoulder sipe 10 may be interrupted in the shoulder land portion 7A.

  The shoulder sipe 10 includes a narrow sipe portion 11 and a thick sipe portion 12 which is wider than the narrow sipe portion 11. The fine sipe portion 11 has, for example, a width of 0.4 to 0.8 mm. The width of the thick sipe portion 12 is, for example, preferably 1.50 to 1.80 times, more preferably 1.60 to 1.70 times the width of the fine sipe portion 11, and specifically, 0.8 It is desirable to have a width of ~ 1.2 mm.

  The thick sipe portion 12 can further reduce the rigidity of the land portion around it compared to the fine sipe portion 11. For this reason, the land portion around the thick sipe portion 12 can easily follow the road surface, for example, even in the initial state of turning when the ground contact load is not sufficiently increased, and excellent initial responsiveness can be obtained.

  The thick sipe portion 12 of the present invention is disposed on the side of the shoulder main groove 3A. At the shoulder main groove 3A side of the shoulder land portion 7A, a ground contact load that is larger than the tread end Te1 side tends to act at the initial stage of turning. Therefore, by providing the thick sipe portion 12 in this region, the initial responsiveness is significantly improved.

  In addition, the land portion around the narrow sipe portion 11 is disposed closer to the tread end Te1 than the thick sipe portion 12 and provides higher rigidity than the land portion around the thick sipe portion 12, for example, sufficient for a tire It is possible to exert a large cornering force in the middle stage of turning under the influence of the ground contact load, and thus to improve the steering stability.

  It is desirable that the thick sipe portion 12 communicate with, for example, the shoulder main groove 3A. The axial length L2 of the thick sipe portion 12 is preferably, for example, 0.15 to 0.30 times the width W2 of the shoulder land portion 7A. Such a thick sipe portion 12 can enhance the resistance to uneven wear and steering stability in a well-balanced manner.

  It is desirable that the fine sipes 11 communicate with the first tread end Te1, for example. Further, it is desirable that the axial length L3 of the fine sipe portion 11 be larger than the axial length L2 of the thick sipe portion 12. Specifically, the length L3 of the thin sipe portion 11 is preferably 3.0 to 4.5 times the length L2 of the thick sipe portion 12, for example.

  The BB sectional drawing of the thick sipe part 12 of FIG. 3 is shown by Fig.4 (a). In FIG.4 (b), CC sectional drawing of the fine sipe part 11 of FIG. 3 is shown. As shown in FIGS. 4A and 4B, the depth d1 of the thick sipe portion 12 is desirably larger than the depth d2 of the thin sipe portion 11. Specifically, the depth d1 of the thick sipe portion 12 is preferably 1.03 times or more, more preferably 1.06 times or more, preferably 1.15 times or less the depth d2 of the thin sipe portion 11 More preferably, it is 1.12 times or less. The depths d1 and d2 correspond to, for example, the distance along the depth direction of the sipe from the tread surface of the land portion to the bottom of the sipe.

  As shown in FIGS. 3 and 4 (a), the shoulder land portion 7A is provided with a narrow groove portion 13 having a groove width of 1.5 mm or more and a groove depth of 2.0 mm or less. It is desirable that 12 extend radially inward from the groove bottom of the narrow groove portion 13. The depth d3 of the narrow groove portion 13 is, for example, 1.0 to 2.0 mm. Such thin groove portion 13 and thick sipe portion 12 can further enhance uneven wear resistance.

  The narrow groove portion 13 extends, for example, outward in the tire axial direction from the shoulder main groove 3A, and terminates between the outer end in the tire axial direction of the thick sipe portion 12 and the first tread end Te1. desirable. The axial length L4 of the narrow groove portion 13 is preferably 1.5 to 2.5 times the axial length L2 of the thick sipe portion 12, for example.

  Between the outer end of the thick sipe portion 12 and the outer end of the narrow groove portion 13, the narrow sipe portion 11 preferably extends inward in the tire radial direction from the groove bottom of the narrow groove portion 13. Further, in the region between the outer end of the narrow groove portion 13 and the first tread end Te1, as shown in FIG. 4B, the narrow sipe portion 11 extends from the bottom to the tread surface with a constant width.

  As shown in FIG. 3, the narrow groove portion 13 is located between the at least one groove wall and the tread contact surface so that the groove width gradually increases toward the shoulder main groove 3A in the communication portion with the shoulder main groove 3A. Is preferably chamfered. In the narrow groove portion 13 of the present embodiment, for example, only one groove wall (the lower groove wall in FIG. 3) has a chamfered portion 14. Such a fine groove portion 13 can reduce air column resonance noise in the outer shoulder main groove 3A while enhancing resistance to uneven wear.

  A plurality of shoulder sipes 10 are arranged at intervals in the circumferential direction of the tire in the shoulder land portion 7A of the present embodiment, and shoulder lug grooves 15 are disposed between the shoulder sipes 10 adjacent in the circumferential direction of the tire. There is. In the present specification, the shoulder lug groove 15 provided in the outer shoulder land portion 7A may be referred to as an outer shoulder lug groove.

  For example, the shoulder lug groove 15 extends inward in the tire axial direction from the first tread end Te1 and terminates without communicating with the shoulder main groove 3A. Such shoulder lug grooves 15 can enhance the wet performance while maintaining the rigidity of the shoulder land portion 7A.

  It is preferable that the tire axial inner end 15 a of the shoulder lug groove 15 be located on the tire axial direction outer side than the tire axial outer end 12 a of the thick sipe portion 12. The axial length L5 of the shoulder lug groove 15 is, for example, preferably 0.45 times or more, more preferably 0.52 times or more, of the axial width W2 of the shoulder land portion 7A, preferably 0 Preferably, it is not more than .65 times, more preferably 0.58 times.

  In order to exert sufficient drainage performance, the groove width W3 of the shoulder lug groove 15 is preferably 1.5 to 2.5 times the groove width W4 of the narrow groove portion 13, for example.

  FIG. 5 shows an enlarged view of the inner shoulder land portion 7B as a view showing another example of the shoulder land portion 7. As shown in FIG. 5, the inner shoulder land portion 7 </ b> B is provided with, for example, a plurality of inner shoulder lug grooves 16. For example, the inner shoulder lug groove 16 extends inward in the axial direction of the tire from the second tread end Te2 and terminates without communicating with the inner shoulder main groove 3B.

  The axial length L6 of the inner shoulder lug groove 16 is, for example, preferably 0.60 or more, more preferably 0.65 or more, the axial width W5 of the inner shoulder land portion 7B in the axial direction, preferably Is preferably 0.76 times or less, more preferably 0.71 times. Such an inner shoulder lug groove 16 can enhance steering stability and wet performance in a well-balanced manner.

  The axial distance L7 from the inner end of the inner shoulder lug groove 16 to the inner shoulder main groove 3B is, for example, the distance L8 from the inner end of the outer shoulder lug groove 15 to the outer shoulder main groove 3A (shown in FIG. 3) It is desirable to be smaller.

  The inner shoulder lug groove 16 has, for example, a groove width W6 greater than 2 mm. The groove width W6 of the inner shoulder lug groove 16 is preferably 0.40 to 0.60 times the groove width W1c (shown in FIG. 1) of the inner shoulder main groove 3B, for example.

  The inner shoulder land portion 7B is provided with an inner shoulder sipe 18 between a connection sipe 17 extending from the inner shoulder lug groove 16 to the inner shoulder main groove 3B and an inner shoulder lug groove 16 adjacent in the tire circumferential direction. .

  The connecting sipes 17 extend inward in the tire radial direction from the groove bottom of the narrow groove portion 19 having a groove width of 1.5 mm or more and a groove depth of 2.0 mm or less, for example. The connection sipes 17 have, for example, a width of 0.4 to 0.8 mm. The dimension of the narrow groove part 19 can apply the dimension of the narrow groove part 13 distribute | arranged to the outer side shoulder land part 7A, for example.

  FIG. 6 is a cross-sectional view of the connection sipes 17 of FIG. 5 taken along the line D-D. As shown in FIG. 6, the connection sipe 17 includes, for example, a first sipe portion 17a on the inner side shoulder lug groove 16 side and a second sipe portion 17b on the inner side shoulder main groove 3B side. The second sipe portion 17 b has, for example, a smaller depth than the first sipe portion 17 a. The depth d13 of the second sipe portion 17b is preferably 0.35 to 0.55 times the depth d12 of the first sipe portion 17a. Such a connection sipe 17 can suppress the excessive opening of the side of the inner shoulder main groove 3B while improving the initial responsiveness, and can also improve the uneven wear resistance.

  As shown in FIG. 5, the inner shoulder sipe 18 extends, for example, along the inner shoulder lug groove 16. The inner shoulder sipe 18 has, for example, both ends interrupted in the inner shoulder land portion 7B. Such an inside shoulder sipe 18 makes it possible to make the land part follow the road surface while suppressing an excessive decrease in the rigidity of the land part, and thus can exhibit excellent steering stability and initial responsiveness.

  The inner shoulder sipes 18, for example, extend inward in the tire radial direction from the groove bottom of the narrow groove portion, like the connection sipes 17 described above.

  In FIG. 7, as an example of the crown land portion 8, an enlarged view of the outer crown land portion 8 </ b> A is shown. As shown in FIG. 7, the outer crown land portion 8 </ b> A is provided with, for example, a crown sipe 21 extending in the tire axial direction with a width of less than 1.5 mm. In the present specification, the crown sipes 21 provided on the outer crown land portion 8A may be referred to as outer crown sipes.

  The crown sipe 21 includes a first crown sipe 26 traversing the outer crown land portion 8A. The first crown sipe 26 relieves the strain at the time of contact with the outer crown land portion 8A and suppresses its uneven wear. The first crown sipes 26 may be referred to as first outer crown sipes.

  The first crown sipe 26 includes a fine sipe portion 22 and a thick sipe portion 23 which is wider than the fine sipe portion 22. The thick sipe portion 23 communicates with the outer shoulder main groove 3A. The dimensions of the thin sipe portion 11 and the thick sipe portion 12 of the outer shoulder sipe 10 described above can be applied to the thin sipe portion 22 and the thick sipe portion 23 of the first crown sipe 26.

  The thick sipe portion 23 can further reduce the rigidity of the land portion around it compared to the fine sipe portion 22. On the other hand, in the crown land portion 8A, the variation of the ground contact load during traveling is larger on the shoulder main groove 3A side than on the crown main groove 4 side, and uneven wear tends to easily occur due to minute slippage of the ground contact surface. In the present embodiment, by providing the thick sipe portion 23 in this region, the land portion around it can easily follow the road surface, and the above-mentioned minute slippage can be suppressed, which further suppresses the partial wear of the crown land portion 8A. be able to.

  In addition, in the outer crown land portion 8A, the land portion around the thick sipe portion 23 can easily follow the road surface even in the initial state of turning, for example, in which the ground contact load is not sufficiently increased. Can.

  Furthermore, in the outer crown land portion 8A, the land portion around the narrow sipe portion 22 is disposed closer to the crown main groove 4 than the narrow sipe portion 22 and provides higher rigidity than the land portion around the large sipe portion 23. Therefore, a large cornering force can be exerted, which in turn can enhance the steering stability.

  Similar to the thick sipe portion 12 of the outer shoulder sipe 10, the large sipe portion 23 desirably extends inward in the tire radial direction from the groove bottom of the narrow groove portion 24. The fine groove portion 24 provided in the crown land portion 8A can apply, for example, the dimension of the thin groove portion 13 provided in the outer shoulder land portion 7A.

  For example, the narrow groove portion 24 is chamfered between at least one groove wall and the tread contact surface so that the groove width gradually increases toward the outer shoulder main groove 3A in the communication portion with the outer shoulder main groove 3A. Is desirable. In the present embodiment, as shown in FIG. 1, the narrow groove portion 13 provided in the outer shoulder land portion 7A has a chamfered portion 14 on the groove wall on one side (lower side in FIG. 1) of the tire circumferential direction. The narrow groove portion 24 provided in the outer crown land portion 8A has a chamfer 25 on the groove wall on the other side (upper side in FIG. 1) of the tire circumferential direction. The chamfered portion 25 provided in the outer crown land portion 8A has a chamfered length in the tire circumferential direction larger than the chamfered portion 14 provided in the outer shoulder land portion 7A. Such an arrangement of the narrow groove portion 24 can improve the resistance to uneven wear, can suppress the generation of standing waves in the outer shoulder main groove 3A, and can reduce air column resonance noise.

  As shown in FIG. 7, the axial length L9 of the thick sipe portion 23 is preferably 0.30 to 0.40 times the width W7 of the outer crown land portion 8A, for example.

  The fine sipes 22 communicate with, for example, the crown main groove 4. It is desirable that the axial length L10 of the fine sipe portion 22 be larger than the axial length L9 of the thick sipe portion 23. The length L10 of the fine sipes 22 is, for example, 1.60 to 1.80 times the length L9 of the thick sipes 23. With such a thick sipe portion 23 and a fine sipe portion 22, a large cornering force can be obtained while exhibiting excellent initial response.

  The fine sipe portion 22 is, for example, chamfered between at least one sipe wall and the tread contact surface so that the width gradually increases toward the crown main groove 4 in the communication portion with the crown main groove. desirable. In the present embodiment, the chamfered portion 28 is provided on the sipe wall on the opposite side (the lower side in FIG. 7) to the chamfered portion 25 provided on the groove wall of the narrow groove portion 24. Such a chamfered portion 28 can reduce air column resonance noise of the crown main groove 4 and thus enhance noise performance.

  FIG. 8A shows a cross-sectional view of the first crown sipes 26 of FIG. 7 taken along the line E-E. As shown in FIG. 8 (a), the first crown sipes 26 include, for example, a first sipe portion 26a on the outer shoulder main groove 3A side and a second sipe portion 26b on the crown main groove 4 side. . The second sipe portion 26 b has, for example, a smaller depth than the first sipe portion 26 a. The depth d5 of the second sipe portion 26b is, for example, 0.45 to 0.55 times the depth d4 of the first sipe portion 26a. Such first crown sipes 26 can maintain the rigidity on the tire equator C side of the outer crown land portion 8A while enhancing the initial responsiveness, and can exhibit further excellent steering stability.

  As shown in FIG. 1, it is desirable for the first crown sipes 26 to have a positional deviation between the outer shoulder sipes 10 in the outer shoulder main groove 3A and the tire circumferential direction of 1.0 mm or less. In the present embodiment, the outer shoulder sipe 10 is disposed to be continuous with the first crown sipe 26 via the outer shoulder main groove 3A, and in the preferred embodiment, the outer shoulder sipe 10 is disposed via the shoulder main groove 3A. And includes a portion which is continuous with the first crown sipes 26. The arrangement of such sipes can make the surrounding land portion follow the road more easily, and can further enhance the initial responsiveness.

  As shown in FIG. 7, the crown sipes 21 provided on the outer crown land portion 8 </ b> A include a second crown sipe 27. The second crown sipe 27 extends, for example, from the crown main groove 4 to the side of the outer shoulder main groove 3A and has a break end 29 in the outer crown land portion 8A. The second crown sipes 27 may be referred to as second outer crown sipes.

  The axial length L11 of the second crown sipe 27 is, for example, 0.35 to 0.55 times the axial width W7 of the outer crown land portion 8A, preferably 0.42 to 0.48. It is a double. Further, it is desirable that the discontinuous end 29 of the second crown sipe 27 be positioned closer to the crown main groove 4 than the end portion on the crown main groove 4 side of the thick sipe portion 23 of the first crown sipe 26. Such second crown sipes 27 can suppress an excessive reduction in the rigidity of the outer crown land portion 8A and provide a large cornering force.

  FIG. 8B is a cross-sectional view taken along the line F-F orthogonal to the second crown sipes 27 in FIG. 7. As shown in FIG. 8 (b), the second crown sipes 27 preferably have, for example, an opening 30 whose width extends outward in the tire radial direction. In the present embodiment, the opening 30 is formed by inclining the sipe wall 31 on one side in the tire circumferential direction of the second crown sipe 27. In the second crown sipes 27, for example, the sipe walls 31 on both sides may be inclined. In addition, the second crown sipes 27 may be provided, for example, at the groove bottom of the above-described narrow groove portion.

  FIG. 8C shows a cross-sectional view along line G-G along the second crown sipes 27 of FIG. 7. As shown in FIG. 8C, the second crown sipe 27 desirably includes a first sipe portion 27a on the discontinuous end 29 side and a second sipe portion 27b on the crown main groove 4 side. The second sipe portion 27b has, for example, a smaller depth than the first sipe portion 27a. The depth d7 of the second sipe portion 27b is preferably, for example, 0.45 to 0.55 times the depth d6 of the first sipe portion 27a. Such second crown sipes 27 can prevent the side of the crown main groove 4 from being excessively opened, and can improve uneven wear resistance and steering stability.

  In FIG. 9, as an example of another crown land portion 8, an enlarged view of the inner crown land portion 8 </ b> B of the present embodiment is shown. As shown in FIG. 9, the inner crown land portion 8B is provided with a plurality of crown lug grooves 34 having a width of 1.5 mm or more and a plurality of inner crown sipes 35 having a width of less than 1.5 mm. ing.

  The crown lug groove 34 cooperates with, for example, the inner shoulder main groove 3B to enhance drainage near the inner crown land portion 8B.

  The inner crown sipes 35 include, for example, a first inner crown sipe 36, a second inner crown sipe 37 and a third inner crown sipe 38. The first inner crown sipes 36 extend from the respective inner ends of the crown lug grooves 34 to the crown main groove 4. The second inner crown sipes 37 extend from the inner shoulder main groove 3B to the side of the crown main groove 4 and have an inner end in the inner crown land portion 8B. The third inner crown sipe 38 extends from the crown main groove 4 to the side of the inner shoulder main groove 3B and has an outer end within the inner crown land portion 8B. These sipes provide frictional force on the wet road surface with their respective edges. In addition, since a relatively large contact pressure acts on the inner crown land portion 8B, the wet performance is significantly enhanced by the action of these grooves and sipes.

  Since the first inner crown sipes 36, the second inner crown sipes 37 and the third inner crown sipes 38 have a width of less than 1.5 mm, they hardly generate pumping noise when grounded. Furthermore, since the first inner crown sipes 36, the second inner crown sipes 37 and the third inner crown sipes 38 moderately reduce the rigidity of the inner crown land portion 8B, the impact sound when the land portion is in contact with the ground can be reduced. Therefore, excellent noise performance can be obtained.

  The axial axial length L12 of the crown lug groove 34 is larger than the axial axial length L13 of the second inner crown sipes 37. As a result, the frequency band between the hitting sound when the edge of the crown lug groove 34 contacts the ground and the hitting sound when the edge of the second inner crown sipe 37 contacts the ground is dispersed, and thus the noise performance is enhanced. Further, the crown lug groove 34, which is longer than the sipes, can also be expected to have high drainage performance.

  In order to further enhance the above-mentioned effects, the length L12 of the crown lug groove 34 is preferably 105% or more, more preferably 108% or more, of the axial length L13 of the second inner crown sipes 37. Preferably it is 120% or less, more preferably 114% or less.

  The crown lug grooves 34 are inclined, for example, with respect to the tire axial direction. For example, it is desirable that the groove width of the crown lug groove 34 be gradually reduced toward the crown main groove 4 side.

  The crown lug groove 34 is chamfered between at least one groove wall and the tread contact surface so that, for example, the groove width gradually increases toward the inner shoulder main groove 3B at the communication portion with the inner shoulder main groove 3B. Is desirable. In the present embodiment, a chamfered portion 39 is provided on one groove wall of the crown lug groove 34. In a desirable mode, a chamfered portion 39 of the crown lug groove 34 is provided on the same side as the chamfered portion 25 (shown in FIG. 7) provided in the fine sipe portion 22 of the first outer crown sipes 26 in the tire circumferential direction. Such a crown lug groove 34 can suppress the generation of a standing wave in the inner shoulder main groove 3B while improving the partial wear resistance, and can reduce air column resonance noise.

  The circumferential length L14 of the chamfered portion 39 of the crown lug groove 34 is desirably, for example, 0.15 to 0.30 times the one pitch length P1 of the crown lug groove 34. Thereby, the wet performance and the noise performance can be enhanced in a well-balanced manner.

  The first inner crown sipes 36 are inclined, for example, in the same direction as the crown lug grooves 34. In the present embodiment, one edge of the first inner crown sipes 36 extends smoothly and continuously with the edge of the crown lug groove 34.

  For example, the first inner crown sipes 36 are chamfered between at least one sipe wall and the tread contact surface so that the width gradually increases toward the crown main groove 4 in the communication portion with the crown main groove 4 Is desirable. It is desirable that the first inner crown sipes 36 have chamfers 40, for example, on the side opposite to the chamfers 39 of the crown lug grooves 34 in the tire circumferential direction. This makes it easy to disperse the frequency band between the hitting sound when one edge of the first inner crown sipes 36 and the crown lug groove 34 contacts the road surface and the hitting sound when the other edge contacts the road surface. , Noise performance is enhanced.

  As shown in FIG. 1, each of the first outer crown sipes 26 provided in the outer crown land portion 8A is provided in a position smoothly continuous with the first inner crown sipes 36 via the crown main groove 4. Is desirable. This makes it easier for the land portion around the sipe to follow the road surface, and the initial responsiveness is enhanced.

  FIG. 10A shows a cross-sectional view of the crown lug groove 34 and the first inner crown sipe 36 of FIG. 9 taken along the line H-H. As shown in FIG. 10A, the first inner crown sipe 36 includes a first sipe portion 36a on the crown main groove 4 side and a second sipe portion 36b on the crown lug groove 34 side. desirable.

  The first sipe portion 36 a has, for example, the same depth d 8 as the depth d 14 of the crown lug groove 34. The second sipe portion 36b preferably has a depth d9 smaller than, for example, the first sipe portion 36a. The depth d9 of the second sipe portion 36b is, for example, 0.40 to 0.60 times the depth d8 of the first sipe portion 36a. Such a first inner crown sipe 36 makes it easy to appropriately deform the side of the crown main groove 4 of the inner crown land portion 8B, and can suppress generation of a standing wave in the crown main groove 4, so the crown main The column resonance noise of the groove 4 can be reduced.

  As shown in FIG. 9, the second inner crown sipes 37 and the third inner crown sipes 38 are each disconnected without crossing the center position of the inner crown land portion 8 </ b> B in the tire axial direction. The second inner crown sipes 37 and the third inner crown sipes 38 according to this embodiment have, for example, a smaller axial length than the first inner crown sipes 36. The axial axial length L13 of the second inner crown sipes 37 and the axial axial length L16 of the third inner crown sipes 38 are respectively the axial axial length L15 of the first inner crown sipes 36. Preferably, it is 0.60 to 0.75.

  The second inner crown sipes 37 and the third inner crown sipes 38 are preferably inclined in the same direction as the first inner crown sipes 36 with respect to the tire axial direction, for example. The angle θ1 of the second inner crown sipes 37 with respect to the tire axial direction is desirably, for example, 0 to 20 °. The angle θ2 of the third inner crown sipes 38 with respect to the tire axial direction is desirably larger than the above angle θ1, and is, for example, 20 to 40 °. Such second inner crown sipes 37 and third inner crown sipes 38 serve to whiten noise when the respective edges contact the road surface.

  FIG. 10 (b) shows an I-I line cross-sectional view orthogonal to the second inner crown sipes 37 of FIG. 9. As shown in FIG. 10 (b), it is desirable that the second inner crown sipes 37 have, for example, an opening 41 whose width extends outward in the tire radial direction. In the present embodiment, the opening 41 is formed by the sipe wall 42 on one side in the tire circumferential direction of the second inner crown sipe 37 being inclined. In the second inner crown sipes 37, for example, the sipe walls 42 on both sides may be inclined. Further, the second inner crown sipes 37 may be provided, for example, at the groove bottom of the above-mentioned narrow groove portion.

  As shown in FIG. 1, in the present embodiment, the sloped sipe wall 31 of the second outer crown sipe 27 is disposed on one side (lower side in FIG. 1) of the tire circumferential direction, and the second inner crown sipe 37 Preferably, the inclined sipe wall 42 is disposed on the other side (upper side in FIG. 1) of the tire circumferential direction.

  FIG. 10C shows a JJ cross-sectional view of the second inner crown sipes 37 and the third inner crown sipes 38 of FIG. 9. As shown in FIG. 10 (c), the second inner crown sipes 37 extend at a constant depth and gradually decrease in depth near the inner end. The third inner crown sipe 38 includes a first sipe portion 38 a on the second inner crown sipe 37 side and a second sipe portion 38 b on the crown main groove 4 side. The first sipe portion 38a has, for example, the same depth d10 as the depth d15 of the second inner crown sipe 37. The second sipe portion 38 b has, for example, a depth d11 smaller than that of the first sipe portion 38 a. The depth d11 of the second sipe portion 38b is preferably, for example, 0.45 to 0.55 times the depth d10 of the first sipe portion 38a. Such second inner crown sipes 37 and third inner crown sipes 38 in combination with the above-described first inner crown sipes 36 can improve the wet performance and the noise performance in a well-balanced manner.

  As shown in FIG. 1, it is desirable that each of the second outer crown sipes 27 be provided in a smoothly continuous position with the third inner crown sipes 38 via the crown main groove 4. This makes it easier for the land portion around the sipe to follow the road surface, and the initial responsiveness is enhanced.

  As shown in FIG. 2, it is desirable that the inner edge 43a on the side of the crown main groove 4 of the inner crown land portion 8B and the outer edge 43b on the side of the inner shoulder main groove 3B be chamfered. Similarly, it is desirable that both the inner edge 43a on the side of the crown main groove 4 of the outer crown land portion 8A and the outer edge 43b on the side of the outer shoulder main groove 3A be chamfered. Such land portions can mitigate the hitting noise when the edge contacts the road surface.

  The inner crown land portion 8B and the outer crown land portion 8A desirably have a tread radius of curvature R1 of 560 mm or less. Specifically, it is desirable that the curvature radius R1 be 400 to 500 mm. As a result, the contact pressure acting on the inner crown land portion 8B and the outer crown land portion 8A is enhanced, while the contact pressure acting on the outer shoulder land portion 7A and the inner shoulder land portion 7B is relaxed, and each shoulder land portion 7A, Sound when 7B rolls can be reduced.

  As shown in FIG. 1, the land ratio Lr1 of the region between the tire equator C and the first tread end Te1 is from the land ratio of the land ratio Lr2 of the region between the tire equator C and the second tread end Te2. Is also desirable. Specifically, the land ratio Lr1 is preferably 1.05 to 1.10 times the land ratio Lr2. As a result, the response at the time of steering can be made linear, and excellent steering stability can be exhibited. In the present specification, the “land ratio” is the ratio Sb / Sa of the actual total ground area Sb to the total area Sa of the virtual ground plane where all the grooves and sipes are completely filled.

  FIG. 11 shows a development view of the tread portion 2 of the tire 1 according to another embodiment of the present invention. As shown in FIG. 11, in this embodiment, an outer crown main groove 4A and an inner crown main groove 4B are provided on both sides of the tire equator C. The outer crown main groove 4A is provided between the tire equator C and the outer shoulder main groove 3A. The inner crown main groove 4B is provided between the tire equator C and the inner shoulder main groove 3B.

  In this embodiment, it is desirable for the shoulder main groove 3 to have, for example, a distance L1a from the tire equator C to the groove center line 0.20 to 0.30 times the tread width TW. The crown main groove 4 preferably has a distance L1b from the tire equator C to the groove center line of 0.05 to 0.15 times the tread width TW, for example.

  The tread portion 2 of this embodiment is provided with the above-described main groove, so that the outer shoulder land portion 7A, the inner shoulder land portion 7B, the outer crown land portion 8A, the inner crown land portion 8B, and the central crown The land portion 8C is included. The configuration described above can be applied to the outer shoulder land portion 7A, the inner shoulder land portion 7B, the outer crown land portion 8A, and the inner crown land portion 8B.

  The central crown land portion 8C is divided between the outer crown main groove 4A and the inner crown main groove 4B. For example, a first central crown sipe 45 and a second central crown sipe 46 are provided in the central crown land portion 8C of the present embodiment. The first central crown sipe 45 crosses, for example, the central crown land portion 8C. For example, the second central crown sipes 46 extend from the inner crown main groove 4B toward the tire equator C side, and are interrupted before the tire equator C.

  As mentioned above, although the tire of one embodiment of the present invention was explained in detail, the present invention can be changed and carried out in various modes, without being limited to the above-mentioned specific embodiment.

A tire of size 195 / 65R15 having the basic pattern of FIG. 1 was prototyped based on the specifications of Table 1. As Comparative Example 1, as shown in FIG. 12, a tire having an outer shoulder land portion a in which an outer shoulder sipe b extending with a constant width is disposed was manufactured. As Comparative Example 2, as shown in FIG. 13, a tire in which a thick sipe portion is disposed on the side of the first tread end was manufactured on a trial basis. The outer shoulder sipe b of Comparative Example 1 extends with the same width as the fine sipe portion of the outer shoulder sipe of the embodiment shown in FIG. The thick sipe part and the fine sipe part of Comparative Example 2 each have the same width as that of the embodiment shown in FIG. The tires of Comparative Examples 1 and 2 are substantially the same as the tread portion shown in FIG. 1 except for the configuration of the outer shoulder sipe. The steering stability of each test tire and the uneven wear resistance of the shoulder land were tested. The common specification and test method of each test tire are as follows.
Mounting rim: 15 × 6.5 J
Tire internal pressure: front wheel 250kPa, rear wheel 240kPa
Test vehicle: front wheel drive, displacement 1800cc
Tire installation position: All wheels The test method is as follows.

Steering stability
The steering stability including the initial response when traveling on a dry road surface with the above test vehicle was evaluated by the driver's sense. A result is a score which sets a comparative example to 100, and it shows that steering stability is excellent, so that a numerical value is large.

<Uneven wear resistance>
A wear energy measurement device was used to measure the wear energy of the outer shoulder land. The result is an index based on the abrasion energy of the comparative example being 100. The smaller the numerical value, the smaller the abrasion energy and the better the uneven wear resistance.
The results of the test are shown in Table 1.

  As a result of the test, it was confirmed that the tires of the examples had excellent steering stability and that the uneven wear resistance of the shoulder land portion was enhanced.

2 tread portion Te1 first tread end C tire equator 3A shoulder main groove 7A shoulder land portion 10 shoulder sipe 11 fine sipe portion 12 thick sipe portion

Claims (11)

A tire having a tread portion,
The tread portion includes a first tread end, a shoulder main groove continuously extending in the tire circumferential direction between the first tread end and the tire equator, and a portion between the first tread end and the shoulder main groove Including sectioned shoulder lands,
The shoulder land portion is provided with a shoulder sipe extending in the axial direction of the tire with a width of less than 1.5 mm,
The shoulder sipe includes a fine sipe portion and a thick sipe portion having a width larger than that of the fine sipe portion,
The thick sipe portion is disposed on the side of the shoulder main groove,
tire.   The tire according to claim 1, wherein the thick sipe portion is in communication with the shoulder main groove.   The tire according to claim 1, wherein the fine sipe portion is in communication with the first tread end.   The tire according to any one of claims 1 to 3, wherein a length in the tire axial direction of the fine sipe portion is larger than a length in the tire axial direction of the thick sipe portion.   The tire according to any one of claims 1 to 4, wherein a depth of the thick sipe portion is larger than a depth of the fine sipe portion.   The tire according to any one of claims 1 to 5, wherein the tread portion has a direction of attachment to the vehicle specified, and the first tread end is located outside the vehicle when attached to the vehicle.   A plurality of the shoulder sipes are arranged at intervals in the tire circumferential direction, and extend inward in the tire axial direction from the first tread end between the shoulder sipes adjacent in the tire circumferential direction and in the shoulder main groove The tire according to any one of the preceding claims, wherein shoulder lug grooves are arranged which terminate without communication.   The tire according to claim 7, wherein an inner end in the tire axial direction of the shoulder lug groove is located axially outward of the outer end in the tire axial direction of the thick sipe portion.   The shoulder land portion is provided with a narrow groove portion having a groove width of 1.5 mm or more and a groove depth of 2.0 mm or less, and the thick sipe portion is inward in the tire radial direction from the groove bottom of the narrow groove portion. A tire according to any of the preceding claims, which extends in   The narrow groove portion extends outward in the tire axial direction from the shoulder main groove, and terminates between an outer end in the tire axial direction of the large sipe portion and the first tread end. Tire described.   In the communication with the shoulder main groove, the narrow groove portion is chamfered between at least one groove wall and the tread contact surface so that the groove width gradually increases toward the shoulder main groove. The tire of 10.

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