JP5478241B2 - tire - Google Patents

Description

  The present invention relates to a tire in which a plurality of blocks formed by a circumferential groove extending in the tire circumferential direction and a lateral groove extending in the tread width direction are formed with narrow grooves narrower than the circumferential groove and the lateral groove.

  Conventionally, in a pneumatic tire (hereinafter referred to as a tire) that is mounted on a passenger car or the like, a tread pattern in which a plurality of blocks are formed by a circumferential groove extending in the tire circumferential direction and a lateral groove extending in the tread width direction has been widely adopted. Yes.

  For example, a tire provided with a narrow groove (so-called sipe) that divides a block by extending along the tread width direction is known (see, for example, Patent Document 1). According to this tire, since the blocks are divided by the narrow grooves to form small blocks, the effect of scratching the road surface (so-called edge effect) is increased, and the braking performance is improved.

  However, in such a tire, since the block is divided, the small block located in the rear of the block in the tire rotation direction easily falls (turns over) toward the lateral groove during braking. For this reason, a load, a driving force, etc. concentrate on a part of small block, and uneven wear resistance will fall.

  Therefore, a tire in which a narrow groove extending in a zigzag shape in the tire radial direction is formed is known. According to this tire, at the time of braking, the small blocks adjacent to each other in the tire circumferential direction support each other, and a decrease in uneven wear resistance can be suppressed.

Japanese Patent Laid-Open No. 10-44718 (2nd page, FIGS. 1 to 4)

  However, the conventional tire described above has the following problems. That is, since the narrow grooves are zigzag in the tire radial direction, there is a problem that the mold for manufacturing the tire becomes complicated and the manufacturing cost of the tire increases.

  Accordingly, an object of the present invention is to provide a tire that can achieve both braking performance and uneven wear resistance on a wet road surface while suppressing an increase in manufacturing cost when narrow grooves are formed in a plurality of blocks. .

  In order to solve the above-described problems, the present invention has the following features. First, the first feature of the present invention is that circumferential grooves (a central main groove 10C, an intermediate main groove 10M, and an end-side main groove 10S) extending in the tire circumferential direction (tire circumferential direction TC) and a tread width direction are extended. A tire (pneumatic tire 1) in which a plurality of blocks (block 40) formed by lateral grooves (lateral grooves 30M) are formed with narrow grooves (for example, curved narrow grooves 50) thinner than the circumferential grooves and the lateral grooves. The narrow groove extends along the tire circumferential direction and opens to the lateral groove, and the circumferential position located on the inner side in the tread width direction of the block. The second narrow groove portion (second narrow groove portion 52) that opens in the direction groove, and the first narrow groove portion and the second narrow groove portion are connected to each other.

  According to such a feature, the narrow groove is constituted by a first narrow groove portion that opens to the lateral groove and a second narrow groove portion that opens to the circumferential groove located inside the tread width direction of the block. The first narrow groove portion and the second narrow groove portion are continuous. According to this, since the block is not divided in the tire circumferential direction by the narrow groove, it is possible to suppress a decrease in rigidity of the small block formed by the narrow groove. That is, the small blocks are not easily deformed independently, and the rigidity of the entire block can be secured. For this reason, it is difficult for the small block to fall down (turn over) toward the lateral groove, and it is possible to prevent a load, a driving force, or the like from concentrating on a part of the small block, and thus it is possible to more reliably suppress a decrease in uneven wear resistance.

  In particular, at the time of braking, the lateral force generated in the tire increases in the region outside the tread width direction in the block. However, since the second narrow groove portion opens in the circumferential groove located on the inner side in the tread width direction of the block, the size of the small block formed on the outer side in the tread width direction by the narrow groove is equal to the inner width direction in the tread width It becomes larger than the size of the small block formed in the. For this reason, the rigidity of the small block formed in the tread width direction outer side is ensured, and the rigidity fall of the whole block can be suppressed. Therefore, it is possible to more reliably suppress a decrease in uneven wear resistance. In addition, since the second narrow groove portion opens into the circumferential groove located on the inner side in the tread width direction of the block, rainwater flowing through the circumferential groove can be easily discharged from the second narrow groove portion 52, and drainage performance is also improved. improves.

  Further, the second narrow groove portion opens in a circumferential groove located on the inner side in the tread width direction of the block, that is, toward the inner side in the tread width direction. That is, the second narrow groove portion extends along the tread width direction. Therefore, the effect of scratching the road surface (so-called edge effect) can be ensured, and the braking performance (driving performance) on the wet road surface can be ensured.

  In this way, compared with conventional narrow grooves that are complex in the tire radial direction, the shape of the narrow grooves is simple, and while suppressing increase in tire manufacturing costs, both braking performance and uneven wear resistance on wet road surfaces are achieved. it can.

A second feature of the present invention is according to the first feature of the present invention, wherein the circumferential groove includes an inner circumferential groove (intermediate main groove 10M) located on the inner side in the tread width direction of the block, and the inner circumferential groove. Including an outer circumferential groove (end-side main groove 10S) positioned on the outer side in the tread width direction of the block, the depth of the inner circumferential groove (intermediate groove depth D _10M ) The gist is that it is shallower than the depth of the outer circumferential groove (end groove depth D _10s ).

  A third feature of the present invention is related to the first or second feature of the present invention, wherein a rib-like land portion (center side land portion) extending along the tire circumferential direction is formed on the inner side in the tread width direction of the inner circumferential groove. The summary is that the columns 20C) are adjacent.

  A fourth feature of the present invention relates to the first to third features of the present invention, and is summarized in that the first narrow groove portion and the second narrow groove portion are connected in a curved shape in a tread surface view. And

A fifth feature of the present invention relates to the second to fourth features of the present invention, wherein the lateral groove is formed on the inner side in the tread width direction of the block and is deeper than the depth of the inner circumferential groove. and (deep lateral grooves region 31), the first formed in the tread width direction outer side than the lateral groove area, the depth of the first lateral groove region shallower than the (deep lateral groove depth D ₃₁₎ a second transverse groove region (shallow lateral groove area 32), and the block is divided by the fine groove and the first small block (first small block 41) having the predetermined surface area on the tread surface among the small blocks divided by the fine groove. Among the small blocks, a second small block (second small block 42) having a surface area larger than the predetermined surface area on the tread surface is provided, and the first small block is a surface in contact with the road surface (block table). 41a), side surfaces (circumferential side surface 41b and width side surface 41c) along the circumferential groove and the lateral groove, a chamfered portion (chamfered portion) that is continuous with the surface and the side surface and is inclined with respect to the tread normal. 41d).

  According to a feature of the present invention, there is provided a tire capable of achieving both braking performance and uneven wear resistance on a wet road surface while suppressing an increase in manufacturing cost when narrow grooves are formed in a plurality of blocks. Can do.

FIG. 1 is a plan development view showing a tread pattern of a pneumatic tire 1 according to the present embodiment. FIG. 2 is a perspective view showing a part of the pneumatic tire 1 according to the present embodiment. FIG. 3 is a cross-sectional view in the tread width direction showing a part of the pneumatic tire 1 along F3-F3 in FIG. FIG. 4 is a cross-sectional view showing a part of the pneumatic tire 1 along F4-F4 of FIG. FIG. 5 is a cross-sectional view showing a part of the pneumatic tire 1 along F5-F5 of FIG.

  Next, an embodiment of a pneumatic tire according to the present invention will be described with reference to the drawings. Specifically, (1) Pneumatic tire configuration, (2) Intermediate main groove configuration, (3) Intermediate land section configuration, (4) Comparative evaluation, (5) Action and effect, (6) Others The embodiment will be described.

  In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones.

  Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings may be contained.

(1) Configuration of Pneumatic Tire First, the configuration of the pneumatic tire 1 according to the present embodiment will be described with reference to the drawings. FIG. 1 is a plan development view showing a tread pattern of a pneumatic tire 1 according to the present embodiment. The pneumatic tire 1 may be filled with an inert gas such as nitrogen gas instead of air. The tread pattern of the pneumatic tire 1 is symmetric (so-called point symmetry) with respect to a point on the tire equator line CL.

  As shown in FIGS. 1 and 2, land sections are formed in the pneumatic tire 1 by circumferential grooves extending along the tire circumferential direction TC.

  Specifically, the circumferential groove includes a central main groove 10C, a pair of intermediate main grooves 10M (inner circumferential grooves), and a pair of end-side main grooves 10S (outer circumferential grooves).

  The central main groove 10C is formed in the tread width direction TW inside of the intermediate land portion row 20M (a block 40 described later) and on the tire equator line CL. The intermediate main groove 10M is formed on the outer side of the tread width direction TW than the central main groove 10C, and is formed on the inner side of the end side main groove 10S in the tread width direction TW. The end-side main groove 10S is formed on the outer side in the tread width direction TW than the central main groove 10C and the intermediate main groove 10M. Details of the intermediate main groove 10M will be described later.

  On the other hand, the land portion row includes a center side land portion row 20C, a pair of intermediate land portion rows 20M, and a pair of outer end land portion rows 20S.

  The center side land portion row 20C is located inside the intermediate land portion row 20M (block 40 described later) in the tread width direction TW, and is formed by the center main groove 10C and the intermediate main groove 10M. The center side land portion row 20C is formed in a rib shape extending continuously along the tire circumferential direction TC. The center side land portion row 20C constitutes a rib-like land portion.

  The intermediate land portion row 20M is located outside the center side land portion row 20C in the tread width direction TW, and is formed by the intermediate main groove 10M and the end side main groove 10S. The details of the intermediate land portion row 20M will be described later.

  The outer end land portion row 20S is provided outside the intermediate land portion row 20M in the tread width direction TW, that is, outside the end side main groove 10S. A plurality of lateral grooves 30S extending along the tread width direction TW are formed in the outer end land portion row 20S. The lateral groove 30S does not open to the end-side main groove 10S and terminates in the outer end land portion row 20S.

(2) Configuration of Intermediate Main Groove Next, the configuration of the above-described intermediate main groove 10M will be described with reference to FIGS. FIG. 2 is a perspective view showing a part of the pneumatic tire 1 according to the present embodiment. FIG. 3 is a cross-sectional view in the tread width direction showing a part of the pneumatic tire 1 along F3-F3 in FIG.

  As shown in FIGS. 2 and 3, the intermediate main groove 10 </ b> M constitutes an inner circumferential groove formed inside the tread width direction TW of the intermediate land portion row 20 </ b> M (block 40 described later). The above-mentioned center side land portion row 20C is provided inside the intermediate main groove 10M in the tread width direction TW, specifically between the central main groove 10C and the intermediate main groove 10M.

Here, in the present embodiment, the depth along the tire radial direction TR of the central main groove 10C (hereinafter referred to as the central groove depth _D10c ) and the depth along the tire radial direction TR of the end-side main groove 10S. (Hereinafter, the end groove depth D _10s ) is substantially the same.

The depth of the intermediate main groove 10M along the tire radial direction TR (hereinafter, the intermediate groove depth D _10M ) is shallower than the central groove depth D _10c and the end groove depth D _10s . Specifically, the intermediate groove depth D _10M is preferably 45 to 55% of the central groove depth D _10c and the end groove depth D _10s .

The width along the tread width direction TW of the intermediate main groove 10M (hereinafter referred to as intermediate groove width W _10M ) is the width along the tread width direction TW of the central main groove 10C (hereinafter referred to as central groove width W _10c ) and the end portion. The side main groove 10S is narrower than the width along the tread width direction TW (hereinafter, the end groove width W _10s ). That is, the central main groove 10C and the end-side main groove 10S are thicker than the intermediate main groove 10M.

Further, the intermediate groove width _W10M is narrower than the width along the tread width direction TW of the center side land portion row 20C (hereinafter, center side land width _W20C ). Specifically, the intermediate groove width W _10M is preferably ₂₀ to 30% (for example, 25%) of the center side land width W _20C .

(3) Configuration of Intermediate Land Section Row Next, the configuration of the above-described intermediate land portion row 20M will be described with reference to FIGS. FIG. 4 is a cross-sectional view showing a part of the pneumatic tire 1 along F4-F4 in FIG. FIG. 5 is a cross-sectional view showing a part of the pneumatic tire 1 along F5-F5 of FIG.

  As shown in FIGS. 1 and 2, the intermediate land row 20M is configured by providing a plurality of blocks 40 along the tire circumferential direction TC. The block 40 is formed by the intermediate main groove 10M and the end-side main groove 10S described above, and a plurality of lateral grooves 30M extending in the tread width direction TW.

In block 40, the circumferential grooves and lateral grooves narrower than 30M, and narrow groove having substantially the same depth as the middle groove depth D _10M is formed. The narrow groove includes a curved narrow groove 50 that is curved in a tread surface view, and a linear straight groove 60 that is linear along the tire circumferential direction TC.

(3.1) Configuration of Block The block 40 includes a plurality of small blocks divided by the curved fine groove 50. Specifically, the block 40 includes a first small block 41 and a second small block 42.

  The first small block 41 has a predetermined surface area on the tread surface among the small blocks divided by the curved narrow groove 50. On the other hand, the second small block 42 has a surface area larger than a predetermined surface area (that is, the surface area of the first small block 41) on the tread surface among the small blocks divided by the curved fine groove 50.

  Here, as shown in FIGS. 3 to 5, the first small block 41 includes a block surface 41a, a circumferential side surface 41b, a width direction side surface 41c, and a chamfered portion 41d.

  The block surface 41a contacts the road surface. The block surface 41a is substantially orthogonal to the tread normal line RL along the tire radial direction TR from the tire rotation axis.

  The circumferential side surface 41b is provided along the intermediate main groove 10M. The width direction side surface 41c is provided along the lateral groove 30M. The circumferential side surface 41b and the width direction side surface 41c (hereinafter simply referred to as “block side surface”) are formed along the tread normal RL (that is, the block surface 41a).

  The chamfered portion 41d is connected to the block surface 41a and the block side surface, and is inclined (γ in FIGS. 3 to 5) with respect to the tread normal RL. In particular, the chamfered portion 41d is preferably inclined at an angle of 50 to 75 degrees with respect to the orthogonal line RIL orthogonal to the tread normal line RL.

  Similarly to the first small block 41, the second small block 42 includes a block surface 42a that contacts the road surface, a circumferential side surface 42b along the end-side main groove 10S, and a width direction side surface 42c along the lateral groove 30M. At least.

  A taber portion 44 is provided at at least one corner of the second small block 42. In the taber portion 44, the block surface 42a in contact with the road surface is gradually inclined toward the inner side in the tire radial direction TR. In the present embodiment, the taber portion 44 is provided at an acute angle portion in the second small block 42 in the tread surface view.

The second small block 42 has a notch 45 formed therein. The notch 45 opens into the end-side main groove 10S. The notch 45 is provided on a parallel line L ₁ (see FIG. 1) parallel to the lateral groove 30M through a portion where a first narrow groove portion 51, which will be described later, is opened in the intermediate main groove 10M. The depth of the notch ₄₅ along the tire radial direction TR (hereinafter, notch depth D ₄₅ ) is substantially the same as the intermediate groove depth D _10M .

(3.2) Configuration of transverse groove The transverse groove 30M is inclined (α in FIG. 1) with respect to a straight line L ₂ (see FIG. 1) along the tire circumferential direction TC in the tread surface view. In particular, the transverse grooves 30M are preferably inclined at 60 degrees or less with respect to the straight line L ₂ along the tire circumferential direction. The transverse groove 30M includes a deep transverse groove region 31 (first transverse groove region) and a shallow transverse groove region 32 (second transverse groove region).

  The deep transverse groove region 31 is formed inside the intermediate land row 20M (block 40) in the tread width direction TW. That is, the deep lateral groove region 31 is formed closer to the tire equator line CL (intermediate main groove 10M) than the shallow lateral groove region 32. On the other hand, the shallow lateral groove region 32 is formed outside the deep lateral groove region 31 in the tread width direction TW outside (on the end side main groove 10S side).

As shown in FIG. 5, the depth along the tire radial direction TR of the deep transverse groove region 31 (hereinafter, deep transverse groove depth D ₃₁ ) is deeper than the intermediate groove depth D _10M . The depth along the tire radial direction TR of the shallow transverse groove region 32 (hereinafter, shallow transverse groove depth D ₃₂ ) is shallower than the deep transverse groove depth D ₃₁ . In the present embodiment, the shallow lateral groove depth D ₃₂ is substantially the same as the middle groove depth D _10M.

  Here, the length along the tread width direction TW of the deep lateral groove region 31 (hereinafter referred to as the deep lateral groove length L31) is the length along the tread width direction TW of the shallow lateral groove region 32 (hereinafter referred to as the shallow lateral groove length L32). ) (See FIG. 5). The deep lateral groove length L31 is longer than the length of the first small block 41 along the tread width direction TW (hereinafter referred to as the first small length L41).

(3.3) Configuration of Curved Fine Groove The curved fine groove 50 includes a first fine groove portion 51 and a second fine groove portion 52. The first narrow groove portion 51 extends along the tire circumferential direction TC and opens into the lateral groove 30M. The second narrow groove portion 52 is continuous with the first narrow groove portion 51 and opens into the intermediate main groove 10M. Further, the first narrow groove portion 51 and the second narrow groove portion 52 are connected in a curved shape in the tread surface view.

  The second narrow groove portion 52 is formed at a position that does not overlap the first narrow groove portion 51 in the tread width direction TW. That is, the second narrow groove portion 52 is continuous with the first narrow groove portion 51 along the tire circumferential direction TC.

The second narrow groove portion 52 is inclined (β in FIG. 1) with respect to a straight line L ₂ (see FIG. 1) along the tire circumferential direction TC in the tread surface view. In particular, the second narrow groove portion 52 is preferably inclined at 60 degrees or less with respect to the straight line L ₂ along the tire circumferential direction TC.

(4) Comparative Evaluation Next, in order to further clarify the effect of the present invention, comparative evaluation performed using pneumatic tires according to the following comparative examples and examples will be described. Specifically, (4.1) Test method and (4.2) Evaluation result will be described. In addition, this invention is not limited at all by these examples.

(4.1) Test method In the comparative evaluation, tests for uneven wear resistance and braking performance were performed.

  In the uneven wear resistance test, the level difference of heel and toe wear in each pneumatic tire was comparatively evaluated after running 10,000 km on a test vehicle equipped with each pneumatic tire. In addition, the smaller the index, the smaller the wear amount and the better the uneven wear resistance.

  In the test of the braking performance, a comparative evaluation was made on the braking distance until the vehicle stopped at a sudden braking after running on a wet road surface at 60 km / h with a test vehicle equipped with each pneumatic tire. The larger the index, the shorter the braking distance and the better the braking performance.

(4.2) Evaluation Results Data regarding each pneumatic tire was measured under the following conditions.

・ Tire size: 195 / 65R15
・ Vehicle conditions: Sedan type passenger car (displacement: 1500cc)
Table 1 shows the evaluation results of the pneumatic tire with the narrow groove shape changed. Table 2 shows the evaluation results of the pneumatic tire changing its angle to the straight line L ₂ of the second narrow groove portion 52. Table 3 shows the evaluation results of the pneumatic tire in which the ratio of the intermediate groove width W _{10M to} the center side land width W _20C is changed. Table 4 shows the evaluation results of the pneumatic tire in which the angle of the chamfered portion 41d with respect to the orthogonal line RIL is changed.

As shown in Table 1, it can be seen that when the narrow groove opens into the central main groove 10C, both the partial wear resistance and the braking performance can be achieved.

As shown in Table 2, by an angle β relative to the straight line L ₂ of the second narrow groove portion 52 is less than 60 degrees, it can be seen that both uneven wear resistance and the braking performance.

As shown in Table 3, when the intermediate groove width W _10M is ₂₀ to 25% of the center side land width W _20C , it can be seen that both uneven wear resistance and braking performance can be achieved.

  As shown in Table 4, it can be seen that when the angle γ of the chamfered portion 41d with respect to the orthogonal line RIL is 50 to 75 degrees, both uneven wear resistance and braking performance can be achieved.

(5) Action / Effect In the embodiment, the curved narrow groove 50 includes a first narrow groove portion 51 that opens to the lateral groove 30M and a second narrow groove portion 52 that opens to the intermediate main groove 10M. Further, the first narrow groove portion 51 and the second narrow groove portion 52 are continuous. According to this, since the block 40 is not divided in the tire circumferential direction TC by the curved fine groove 50, it is possible to suppress a decrease in rigidity of the small block formed by the curved fine groove 50. That is, the small blocks are not easily deformed independently, and the rigidity of the entire block 40 can be secured. For this reason, the small block is unlikely to fall (turn over) toward the lateral groove 30M, and it is possible to prevent a load, a driving force, etc. from concentrating on a part of the small block, and thus it is possible to more reliably suppress a decrease in uneven wear resistance.

  In particular, at the time of braking, the lateral force generated in the pneumatic tire 1 becomes large in the region outside the tread width direction TW in the block 40. However, when the second narrow groove portion 52 opens into the intermediate main groove 10M, the size of the second small block 42 formed outside the tread width direction TW by the curved narrow groove 50 is reduced by the curved narrow groove 50. It becomes larger than the size of the first small block 41 formed inside the tread width direction TW. For this reason, the rigidity of the 2nd small block 42 is ensured, and the rigidity fall of the block 40 whole can be suppressed. Therefore, it is possible to more reliably suppress a decrease in uneven wear resistance. Further, since the second narrow groove portion 52 opens into the intermediate main groove 10M, rainwater or the like flowing through the intermediate main groove 10M formed near the tire equator line CL can be easily discharged from the second narrow groove portion 52. Performance is also improved.

  Further, the second narrow groove portion 52 opens into the intermediate main groove 10M, that is, toward the inside of the tread width direction TW. That is, the second narrow groove portion 52 extends along the tread width direction TW. Therefore, the effect of scratching the road surface (so-called edge effect) can be ensured, and the braking performance (driving performance) on the wet road surface can be ensured.

  As described above, the curved narrow groove 50 has a simpler shape than the conventional narrow grooves complicated in the tire radial direction, and suppresses an increase in the manufacturing cost of the tire, while maintaining braking performance and resistance to uneven wear on the wet road surface. Both sexes can be achieved.

In the embodiment, the intermediate groove depth D _10M is shallower than the central groove depth D _10c . According to this, the volume of the intermediate main groove 10M is not excessively reduced.

In particular, the intermediate groove depth D _10M is preferably 45 to 55% of the central groove depth D _10c and the end groove depth D _10s . When the intermediate groove depth D _10M is smaller than 45% of the central groove depth D _10c and the end groove depth D _10s , the volume of the intermediate main groove 10M is excessively reduced, and the drainage performance cannot be ensured. There is. On the other hand, if the intermediate groove depth D _10M is larger than 55% of the central groove depth D _10c and the end groove depth D _10s , it is difficult to secure the rigidity of the block 40 and the braking performance may be deteriorated. .

Further, the intermediate groove width W _10M is preferably ₂₀ to 30% of the center side land width W _20C . If the intermediate groove width W _10M is smaller than 20% of the center side land width W _20C , the volume of the intermediate main groove 10M is excessively reduced, and the drainage performance may not be ensured. On the other hand, if the intermediate groove width W _10M is larger than 30% of the center side land width W _20C , it is difficult to secure the rigidity of the block 40, and the braking performance may be deteriorated.

  In the embodiment, the above-described center-side land portion row 20C is provided inside the intermediate main groove 10M in the tread width direction TW, specifically, between the central main groove 10C and the intermediate main groove 10M. According to this, the rigidity of the block 40 (particularly, the first small block 41 adjacent to the intermediate main groove 10M) can be secured. For this reason, it is possible to prevent the contact pressure of the entire pneumatic tire 1 from becoming uneven, and to more reliably suppress a reduction in braking performance.

  In the embodiment, the first narrow groove portion 51 and the second narrow groove portion 52 are continuous in a curved shape in the tread surface view. According to this, rainwater or the like flowing through the intermediate main groove 10M can be easily discharged from the second narrow groove portion 52 while ensuring braking performance on the wet road surface, so that the drainage performance is further improved.

In the embodiment, the deep transverse groove depth D ₃₁ is deeper than the intermediate groove depth D _{10 M} , and the shallow transverse groove depth D is shallower than the deep transverse groove depth D. According to this, the rigidity of the block 40 (particularly, the second small block 42 adjacent to the end-side main groove 10S) can be secured, so that the ground pressure of the entire pneumatic tire 1 is further prevented from becoming uneven. Thus, it is possible to more reliably suppress a decrease in braking performance.

Further, transverse grooves 30M and a second narrow groove portion 52, the tread surface view, inclined with respect to the straight line _{L 2} along the tire circumferential direction TC (in FIG. 1 alpha, beta) is. According to this, rainwater or the like flowing through the intermediate main groove 10M is easily discharged from the second narrow groove portion 52 while ensuring the edge effect, so that both braking performance and drainage performance on the wet road surface can be achieved at a high level. .

In particular, the transverse grooves 30M and a second narrow groove portion 52 is preferably inclined at 60 degrees or less with respect to the straight line _{L 2.} Incidentally, the transverse grooves 30M and the second narrow groove portion 52 is greater than 60 degrees with respect to the straight line L _2, the input along the tire circumferential direction TC than when driving block 40 (first small block 41 and the second small block 42) It becomes easy to concentrate on the edge. For this reason, at the time of braking, the block 40 is likely to fall down (turn over) toward the lateral groove 30M, and deterioration of uneven wear resistance may not be suppressed.

  The second small block 42 has a surface area larger than a predetermined surface area on the tread surface among the small blocks divided by the curved narrow groove 50. That is, the second small block 42 is provided outside the tread width direction TW where the lateral force generated in the pneumatic tire 1 in the block 40 is large during braking. For this reason, the rigidity of the 2nd small block 42 is ensured, and the fall of uneven wear resistance can be suppressed more reliably.

  The first small block 41 includes a chamfered portion 41d in addition to the block surface 41a and the block side surface. According to this, the volume of the intermediate main groove 10M increases while securing the rigidity of the first small block 41. For this reason, uneven wear resistance and drainage performance can be achieved at a high level.

  In particular, the chamfered portion 41d is preferably inclined at an angle (γ) of 50 to 75 degrees with respect to the orthogonal line RIL. If the chamfered portion 41d is inclined with respect to the orthogonal line RIL at an angle smaller than 50 degrees, the contact area of the first small block 41 (that is, the area of the block surface 41a) is excessively reduced, and the braking performance is improved. There are cases where it is not possible. On the other hand, if the chamfered portion 41d is inclined with respect to the orthogonal line RIL at an angle larger than 75 degrees, the volume of the intermediate main groove 10M is difficult to increase, and the drainage performance may be deteriorated.

(6) Other Embodiments As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. However, it is understood that the description and drawings constituting a part of this disclosure limit the present invention. Should not. From this disclosure, various alternative embodiments, examples, and operational techniques will be apparent to those skilled in the art.

  For example, the embodiment of the present invention can be modified as follows. Specifically, the tire has been described as the pneumatic tire 1 filled with air, nitrogen gas, or the like, but is not limited thereto, and may be a solid tire (no puncture tire).

  Also, it goes without saying that the configuration and tread pattern of the pneumatic tire 1 can be appropriately set according to the purpose. For example, the tread pattern of the pneumatic tire 1 may be symmetric (so-called line symmetry) with respect to the tire equator line CL. Further, a lateral groove may be formed in the center side land portion row 20C, and the narrow groove described in the embodiment may be provided.

The second narrow groove portion 52 is not necessarily inclined at 60 degrees or less with respect to the straight line L ₂ along the tire circumferential direction TC, may be greater than 60 degrees with respect to the straight line L _2. Further, the first narrow groove portion 51 and the second narrow groove portion 52 do not necessarily have to be connected in a curved shape in the tread surface view, and may be bent. Further, the lateral groove 30M does not necessarily include the deep lateral groove region 31 and the shallow lateral groove region 32, and may be only one of them. Further, the block 40 is not necessarily provided with the chamfered portion 41 d and the taber portion 44.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is determined only by the invention specifying matters according to the scope of claims reasonable from the above description.

DESCRIPTION OF SYMBOLS 1 ... Pneumatic tire, 10C ... Central side main groove, 10S ... End side main groove, 20C ... Central land part row | line | column, 20M ... Middle land part row | line | column, 20S ... Outer end land part row | line | column, 30M, 30S ... Cross groove, 31 ... deep lateral groove region (first lateral groove region), 32 ... shallow lateral groove region (second lateral groove region), 40 ... block, 41 ... first small block, 41a ... block surface, 41b ... circumferential side surface, 41c ... width side surface , 41d ... chamfered portion, 42 ... second small block, 42a ... block surface, 42b ... circumferential side surface, 42c ... width side surface, 44 ... taber portion, 45 ... notch portion, 50 ... curved narrow groove, 51 ... First narrow groove portion, 52 ... second narrow groove portion, 60 ... straight narrow groove

Claims (6)

A tire in which a plurality of blocks formed by a circumferential groove extending in the tire circumferential direction and a lateral groove extending in the tread width direction are formed with narrow grooves narrower than the circumferential groove and the lateral groove,
The narrow groove is
A curved thin line formed by a first narrow groove portion extending along the tire circumferential direction and opening in the transverse groove and a second narrow groove portion opening in the circumferential groove located inside the tread width direction of the block. Groove,
And linear straight grooves along the tire circumferential direction,
The first narrow groove portion and the second narrow groove portion are continuous ,
One end of the linear narrow groove opens to the lateral groove, and the other end of the linear narrow groove terminates in the block,
The tire in which the linear narrow groove is opened on one side of the lateral groove in the tire circumferential direction, and the first narrow groove portion is opened on the other side of the lateral groove in the tire circumferential direction . The circumferential groove is
An inner circumferential groove located inside the tread width direction of the block;
An outer circumferential groove that is thicker than the inner circumferential groove and is located on the outer side in the tread width direction of the block;
The tire according to claim 1, wherein a depth of the inner circumferential groove is shallower than a depth of the outer circumferential groove. The tire according to claim 2, wherein a rib-like land portion extending along the tire circumferential direction is adjacent to an inner side in the tread width direction of the inner circumferential groove.   The tire according to any one of claims 1 to 3, wherein the first narrow groove portion and the second narrow groove portion are connected in a curved shape in a tread surface view. The lateral groove is
A first lateral groove region formed on the inner side in the tread width direction of the block and deeper than the depth of the inner circumferential groove;
A second lateral groove region that is formed outside the first lateral groove region in the tread width direction and is shallower than a depth of the first lateral groove region;
The block is
Among the small blocks divided by the narrow groove, a first small block having a predetermined surface area on the tread surface,
Among the small blocks divided by the narrow groove, a second small block having a surface area larger than the predetermined surface area on the tread surface,
The first small block is:
A surface in contact with the road surface;
Side surfaces along the circumferential grooves and the lateral grooves;
The tire according to any one of claims 2 to 4, further comprising a chamfered portion that is continuous with the surface and the side surface and is inclined with respect to a tread normal.   The circumferential groove has an intermediate main groove located on the inner side in the tread width direction of the block, and an end side main groove located on the outer side in the tread width direction of the block,
  The second small block has a notch,
  The first narrow groove portion opens into the intermediate main groove,
  The notch is open to the end-side main groove,
The tire according to claim 5, wherein the notch portion is provided on a parallel line passing through a portion where the first narrow groove portion is opened in the intermediate main groove and parallel to the lateral groove.

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