JP7138657B2 - tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a tire having blocks in the tread portion.

A tire used on an icy road surface has a tread pattern set according to the performance of the tire on the icy road surface (on-ice performance), and various blocks are formed in the tread portion. Further, conventionally, a pneumatic tire is known in which two sipes are formed in the central portion of a block in the tire circumferential direction to improve performance on ice (see Patent Document 1).

In order to further improve the performance on ice of the pneumatic tire described in Patent Document 1, it is common to increase the number of sipes formed in the block to increase the edge component within the block. However, as the number of sipes increases, the portion of the block partitioned by the sipes (partition block) becomes smaller, and the partition block is more likely to deform when the vehicle is running. Therefore, there is an increased need to deal with missing partition blocks. Therefore, the conventional tire has room for further improvement from the viewpoint of improving both the chipping resistance performance of the block and the performance on ice of the tire.

JP-A-2008-149768

SUMMARY OF THE INVENTION An object of the present invention is to improve the on-ice performance of a tire while suppressing the loss of blocks in the tread portion.

The present invention is a tire having blocks in the tread portion. The block has a central sipe formed along the tire width direction on the block tread surface at the center of the block in the tire circumferential direction, and a block tread surface formed along the tire width direction adjacent to both sides of the central sipe in the tire circumferential direction. and a pair of adjacent sipes. The tire radial depth of the pair of adjacent sipes is smaller than the tire radial depth of the central sipe. The distance in the tire circumferential direction between the end wall of the block in the tire circumferential direction and the adjacent sipe closer to the end wall is equal to or greater than the depth in the tire radial direction of the adjacent sipe.
Further, the present invention is a tire having blocks in the tread portion. The block has a central sipe formed along the tire width direction on the block tread surface at the center of the block in the tire circumferential direction, and a block tread surface formed along the tire width direction adjacent to both sides of the central sipe in the tire circumferential direction. and a side wall extending along the tire circumferential direction between the end walls on both sides in the tire circumferential direction. The tire radial depth of the pair of adjacent sipes is smaller than the tire radial depth of the central sipe. The side wall angle between the tire radial plane and the side wall of the block increases from the center of the block toward the end wall.

ADVANTAGE OF THE INVENTION According to this invention, the on-ice performance of a tire can be improved, suppressing the loss of the block of a tread part.

It is a top view showing the tread pattern of the tire of a 1st embodiment. It is a top view which shows the 1st land part of 1st Embodiment. It is a side view which shows the block of 1st Embodiment. FIG. 4 is a side view showing a state of the block of the first embodiment when grounded; FIG. 4 is a side view showing the block with a part separated from the road surface; It is a perspective view which shows the block of 2nd Embodiment. FIG. 5 is a cross-sectional view of a block of a second embodiment; FIG. 11 is a cross-sectional view showing a state of the block of the second embodiment when it is grounded; FIG. 11 is a plan view showing the tread pattern of the tire of the third embodiment;

One embodiment of the tire of the present invention will be described with reference to the drawings.
The tire of this embodiment is a pneumatic tire for vehicles (for example, a tire for trucks and buses, a tire for heavy loads, and a tire for passenger cars), and is formed into a well-known structure using general tire constituent members. That is, the tire includes a pair of bead portions, a pair of sidewall portions positioned radially outwardly of the pair of bead portions, a tread portion in contact with the road surface, and between the tread portion and the pair of sidewall portions. It has a pair of positioned shoulders. A tire includes a pair of bead cores, a carcass arranged between the pair of bead cores, a belt arranged on the outer peripheral side of the carcass, and a tread rubber having a predetermined tread pattern.

(First embodiment)
FIG. 1 is a plan view showing the tread pattern of the tire 1 of the first embodiment, and schematically shows a portion of the tread portion 2 in the tire circumferential direction S. FIG.
As shown, the tire 1 has a tread portion 2 with a plurality of circumferential grooves 10, 11, a plurality of width direction grooves 13 to 15, a plurality of sipes 20 to 27, a plurality of land portions 30, 40, 50, and , a plurality of blocks 31 , 41 , 51 . When the vehicle is running, the tire 1 rolls in contact with the road surface at a plurality of land portions 30 , 40 , 50 . The outer surfaces in the tire radial direction of the land portions 30, 40, 50 are tread surfaces that come into contact with the road surface.

The plurality of circumferential grooves 10 and 11 are main grooves extending along the tire circumferential direction S, and are arranged side by side in the tire width direction H at intervals. Here, the tire 1 includes four circumferential grooves (two first circumferential grooves 10 and two second circumferential grooves 11) continuously formed in the tire circumferential direction S. As shown in FIG. The first circumferential groove 10 is an inner circumferential groove located on the innermost side (on the tire equatorial plane 3 side) in the tire width direction H among the plurality of circumferential grooves 10 and 11, and is the inner circumferential groove of the second circumferential groove 11. It is formed inside in the tire width direction H. The tire equatorial plane 3 is located at the central portion of the tread portion 2 in the tire width direction H.

The first circumferential grooves 10 are center-side circumferential grooves located on both sides of the tire equatorial plane 3 in the tire width direction H. formed between. The second circumferential groove 11 is an outer circumferential groove located on the outermost side in the tire width direction H (on the side of the shoulder portion 4 ) among the plurality of circumferential grooves 10 and 11 , and is the tire of the first circumferential groove 10 . It is formed outside in the width direction H. The shoulder portion 4 is located outside the tread portion 2 in the tire width direction H. On both sides of the tire equatorial plane 3 , the second circumferential grooves 11 are located inside the shoulder portion 4 in the tire width direction H and are formed between the first circumferential grooves 10 and the shoulder portion 4 .

The plurality of widthwise grooves 13 to 15 are lateral grooves (lug grooves) extending along the tire width direction H, and are formed in the land portions 30 , 40 , 50 . Also, the plurality of widthwise grooves 13 to 15 are formed in a direction intersecting the circumferential grooves 10 and 11 and intersect with the circumferential grooves 10 and 11 . The widthwise grooves 13 to 15 are formed shallower than the circumferential grooves 10, 11, and the groove bottoms of the widthwise grooves 13 to 15 are radially outward of the groove bottoms of the circumferential grooves 10, 11. To position. A plurality of sipes 20 to 27 are cuts formed in the land portions 30, 40, 50 and are formed from the tread surfaces of the land portions 30, 40, 50 toward the inside of the land portions 30, 40, 50.

A plurality of circumferential grooves 10 and 11 partition the tread portion 2 in the tire width direction H, and a plurality of land portions 30 , 40 and 50 are formed in the tread portion 2 . The plurality of land portions 30 , 40 , 50 are convex portions formed outward in the tire radial direction and extend in the tire circumferential direction S along the circumferential grooves 10 , 11 . Moreover, the land portions 30, 40, 50 are block rows having a plurality of blocks 31, 41, 51 arranged in the tire circumferential direction S, and are arranged in parallel in the tire width direction H at intervals.

The tire 1 includes five land portions (one first land portion 30, two second land portions 40, two third land portions 50). The first land portion 30 is a central land portion formed between the two first circumferential grooves 10 and formed in the central region of the tread portion 2 including the tire equatorial plane 3 . The tire equatorial plane 3 is positioned at the center of the first land portion 30 in the tire width direction H. The first land portion 30 is located inside the two second land portions 40 in the tire width direction H.

The first land portion 30 has a plurality of widthwise grooves 13, a plurality of sipes 20 to 23 (divided sipes 20, 21, a central sipe 22, and an adjacent sipe 23), and a plurality of blocks 31 in contact with the road surface. there is On both sides of a center line 32 of the first land portion 30 extending in the tire circumferential direction S, the plurality of width direction grooves 13 are arranged in parallel in the tire circumferential direction S at intervals. A center line 32 of the first land portion 30 is positioned at the center of the first land portion 30 in the tire width direction H and on the tire equatorial plane 3 . One end of the widthwise groove 13 opens into the first circumferential groove 10 , and the other end of the widthwise groove 13 closes within the first land portion 30 .

The width direction grooves 13 on one side of the center line 32 and the width direction grooves 13 on the other side of the center line 32 are formed to be shifted in the tire circumferential direction S. The split sipes 20, 21 are circumferential sipes extending along the tire circumferential direction S, and are formed between the widthwise groove 13 on one side of the center line 32 and the widthwise groove 13 on the other side of the center line 32. there is Both ends of the split sipes 20 and 21 are opened to the width direction grooves 13 , and the first land portion 30 is split in the tire width direction H by the plurality of split sipes 20 and 21 .

A block 31 of the first land portion 30 is a central block located in the central region of the tread portion 2 . A plurality of blocks 31 are partitioned between the two first circumferential grooves 10 by the two first circumferential grooves 10, the plurality of width direction grooves 13, and the plurality of split sipes 20, 21, and the first It is formed in the land portion 30 . A plurality of blocks 31 are arranged in sequence in the tire circumferential direction S on both sides of the center line 32 , and the widthwise grooves 13 are formed between the blocks 31 . The block 31 on one side of the center line 32 and the block 31 on the other side of the center line 32 are shifted in the tire circumferential direction S and formed.

The block 31 has a central sipe 22 formed in a central portion (block central portion 33 ) of the block 31 in the tire circumferential direction S and an adjacent sipe 23 adjacent to the central sipe 22 . The central sipe 22 and the adjacent sipe 23 are width direction sipes extending along the tire width direction H and are adjacent to each other in the tire circumferential direction S. In addition, the central sipe 22 and the adjacent sipes 23 are formed on the block tread surface along the tire width direction H in a state in which they are spaced apart from each other in the tire circumferential direction S, and traverse the block 31 in the tire width direction H. ing. Note that the block center portion 33 is not limited to the center position of the block 31 in the tire circumferential direction S, but is a center region extending in the tire width direction H of the block 31 including the center position in the tire circumferential direction S.

Here the block 31 has a plurality of sipes 22, 23 (one central sipe 22, two adjacent sipes 23) including one central sipe 22; A pair of adjacent sipes 23 are adjacent to both sides of the central sipe 22 in the tire circumferential direction S, and the central sipe 22 is formed between the pair of adjacent sipes 23 . One end of each of the multiple sipes 22 and 23 opens into the first circumferential groove 10 , and the other end of each of the multiple sipes 22 and 23 opens into the split sipe 20 .

The second land portion 40 is an intermediate land portion formed between the first circumferential groove 10 and the second circumferential groove 11, and is located in the intermediate region of the tread portion 2 between the tire equatorial plane 3 and the shoulder portion 4. formed. The second land portion 40 is located between the first land portion 30 and the third land portion 50 on both sides of the tire equatorial plane 3 . The second land portion 40 has a plurality of widthwise grooves 14, a plurality of sipes 24 to 27 (divided sipes 24, 25, a central sipe 26, and an adjacent sipe 27), and a plurality of blocks 41 that come into contact with the road surface. is doing. On both sides of a center line 42 of the second land portion 40 extending in the tire circumferential direction S, the plurality of width direction grooves 14 are arranged in parallel in the tire circumferential direction S at intervals. The center line 42 of the second land portion 40 is positioned at the center of the second land portion 40 in the tire width direction H.

One end of the widthwise groove 14 opens to the first circumferential groove 10 or the second circumferential groove 11 , and the other end of the widthwise groove 14 closes within the second land portion 40 . The width direction grooves 14 on one side of the center line 42 and the width direction grooves 14 on the other side of the center line 42 are formed to be shifted in the tire circumferential direction S. The split sipes 24, 25 are circumferential sipes extending along the tire circumferential direction S, and are formed between the widthwise groove 14 on one side of the center line 42 and the widthwise groove 14 on the other side of the center line 42. there is Both ends of the split sipes 24 and 25 are open to the width direction grooves 14 , and the second land portion 40 is split in the tire width direction H by the plurality of split sipes 24 and 25 .

The blocks 41 of the second land portion 40 are intermediate blocks positioned in the intermediate region of the tread portion 2 . The first circumferential groove 10, the second circumferential groove 11, the plurality of width direction grooves 14, and the plurality of split sipes 24, 25 allow the plurality of blocks 41 to form the first circumferential groove 10 and the second circumferential groove. 11 and formed in the second land portion 40 . A plurality of blocks 41 are arranged in sequence in the tire circumferential direction S on both sides of the center line 42 , and the widthwise grooves 14 are formed between the blocks 41 . The block 41 on one side of the center line 42 and the block 41 on the other side of the center line 42 are shifted in the tire circumferential direction S and formed.

The block 41 has a central sipe 26 formed in a central portion (block central portion 43 ) of the block 41 in the tire circumferential direction S and an adjacent sipe 27 adjacent to the central sipe 26 . The central sipe 26 and the adjacent sipe 27 are width direction sipes extending along the tire width direction H and are adjacent to each other in the tire circumferential direction S. In addition, the central sipe 26 and the adjacent sipes 27 are formed on the block tread surface along the tire width direction H while being spaced apart from each other in the tire circumferential direction S, and traverse the block 41 in the tire width direction H. ing. Note that the block center portion 43 is not limited to the center position of the block 41 in the tire circumferential direction S, but is a center region extending in the tire width direction H of the block 41 including the center position in the tire circumferential direction S.

Here, block 41 has a plurality of sipes 26, 27 (one central sipe 26, two adjacent sipes 27) including one central sipe 26. FIG. A pair of adjacent sipes 27 are adjacent to both sides of the central sipe 26 in the tire circumferential direction S, and the central sipe 26 is formed between the pair of adjacent sipes 27 . One end of each of the plurality of sipes 26 and 27 opens into the first circumferential groove 10 or the second circumferential groove 11, and the other end of each of the plurality of sipes 26 and 27 opens into the split sipe 24. ing.

The third land portion 50 is an outer land portion formed on the outer side of the second circumferential groove 11 in the tire width direction H, and is formed in the outer region of the tread portion 2 in the tire width direction H (region on the shoulder portion 4 side). It is On both sides of the tire equatorial plane 3 , the third land portions 50 are positioned outside the second land portions 40 in the tire width direction H. Also, the third land portion 50 has a plurality of widthwise grooves 15 and a plurality of blocks 51 that come into contact with the road surface. The plurality of width direction grooves 15 are arranged in parallel in the tire circumferential direction S at intervals. One end of the widthwise groove 15 opens to the second circumferential groove 11 , and the other end of the widthwise groove 15 opens to the shoulder portion 4 side.

The blocks 51 of the third land portion 50 are outer blocks located in the outer region of the tread portion 2 . A plurality of blocks 51 are defined outside the second circumferential grooves 11 in the tire width direction H by the second circumferential grooves 11 and the width direction grooves 15 to form the third land portion 50 . A plurality of blocks 51 are arranged in order in the tire circumferential direction S, and width direction grooves 15 are formed between the blocks 51 . The block 51 also has a narrow groove 52 narrower than the widthwise groove 15 and a plurality of sipes 53 . The narrow grooves 52 and the sipes 53 are formed along the tire width direction H.

The first land portion 30 and the second land portion 40 are similarly configured and have the same features with respect to their respective blocks 31,41 and transverse grooves 13,14. Hereinafter, the block 31 and the width direction groove 13 will be described in detail by taking the first land portion 30 as an example. The blocks 41 and the widthwise grooves 14 of the second land portion 40 are the same as the blocks 31 and the widthwise grooves 13 of the first land portion 30, which will be described below, and thus the description thereof is omitted.

FIG. 2 is a plan view showing the first land portion 30 of the first embodiment, showing an enlarged part of FIG. FIG. 3 is a side view showing the block 31 of the first embodiment, and schematically shows the block 31 as seen from the side in the tire width direction H. As shown in FIG.
As illustrated, the first circumferential grooves 10 partition the blocks 31 on the sides of the blocks 31 in the tire width direction H, and the width direction grooves 13 partition the blocks 31 on both sides of the blocks 31 in the tire circumferential direction S. do. The block 31 includes a tread surface (block tread surface 34) formed along the tire circumferential direction S, a side wall 35 positioned within the first circumferential groove 10, an end wall 36 positioned within the width direction groove 13, and a plurality of edge portions 37A and 37B (first edge portion 37A and second edge portion 37B). The block tread surface 34 is an outer surface of the block 31 in the tire radial direction K, and contacts the road surface when the tire 1 rolls (when the vehicle runs). The side wall 35 and the end wall 36 are part of the wall portion of the block 31 and are formed inward in the tire radial direction K from edge portions 37A and 37B located at the edges of the block tread surface 34 .

A side wall 35 of the block 31 is a side surface of the block 31 positioned laterally in the tire width direction H, and defines the first circumferential groove 10 . The side wall 35 is also a groove wall of the first circumferential groove 10 and is formed from the groove bottom of the first circumferential groove 10 to the block tread surface 34 . The central sipe 22 is formed along the tire width direction H on the block tread surface 34 of the block central portion 33 and opens to the side wall 35 . A pair of adjacent sipes 23 are formed on the block tread surface 34 parallel to the central sipe 22 and open to the sidewalls 35 on both sides of the central sipe 22 in the tire circumferential direction S. The side walls 35 and the end walls 36 intersect at positions (corners of the blocks 31) where the first circumferential grooves 10 and the widthwise grooves 13 intersect.

An end wall 36 of the block 31 is an end face of the block 31 located at an end of the block 31 in the tire circumferential direction S, and defines the width direction groove 13 . The end wall 36 is also a groove wall of the width direction groove 13 and is formed from the groove bottom of the width direction groove 13 to the block tread surface 34 . Two end walls 36 are located at both end portions of the block 31 in the tire circumferential direction S, and are located in the width direction grooves 13 on both sides of the block 31 in the tire circumferential direction S. As shown in FIG.

The side wall 35 of the block 31 is a circumferential wall extending along the tire circumferential direction S between the end walls 36 on both sides in the tire circumferential direction S. As shown in FIG. The end walls 36 of the block 31 are width direction walls extending along the tire width direction H at both ends of the block 31 in the tire circumferential direction S. As shown in FIG. The first edge portion 37A is a circumferential edge portion extending along the tire circumferential direction S, and is formed at a position (edge) where the block tread surface 34 and the side wall 35 intersect. The second edge portion 37B is a width direction edge portion extending along the tire width direction H, and is formed at a position (edge) where the block tread surface 34 and the end wall 36 intersect.

The first edge portion 37A is inclined toward the lateral side (outer side) of the block 31 in the tire width direction H with respect to the tire circumferential direction S when viewed from the end wall 36 toward the block center portion 33 . As a result, the sidewall 35 is formed in a convex shape from which the block central portion 33 protrudes, and is inclined with respect to the tire circumferential direction S between the end wall 36 and the block central portion 33 . Further, the side wall 35 in the block central portion 33 is formed with an outer end 35A. The outer end 35A is the outermost portion located on the outermost side in the tire width direction H within the side wall 35 . The central sipe 22 opens to the outer end 35A of the side wall 35, and the adjacent sipes 23 open to the side wall 35 on both sides in the tire circumferential direction S of the outer end 35A.

A block 31 is partitioned in the tire circumferential direction S by the central sipe 22 and the pair of adjacent sipes 23, and a plurality of partition blocks 38A to 38D are formed within the block 31. As shown in FIG. The division blocks 38A to 38D are small blocks that constitute the block 31 and are arranged in order in the tire circumferential direction S. As shown in FIG. The two partition blocks 38A and 38B are outer blocks (hereinafter referred to as first outer block 38A and second outer block 38B) located outside in the tire circumferential direction S within the block 31, and are adjacent to the width direction grooves 13, respectively. It is formed between sipes 23 . The two partition blocks 38C and 38D are inner blocks (hereinafter referred to as the first inner block 38C and the second inner block 38D) located inside the block 31 in the tire circumferential direction S, and are the central sipe 22 and the adjacent sipe 22, respectively. 23 are formed.

The inner blocks 38C, 38D are formed between the two outer blocks 38A, 38B and positioned on both sides of the central sipe 22 in the tire circumferential direction S. Adjacent sipes 23 are formed between inner blocks 38C, 38D and outer blocks 38A, 38B, and central sipes 22 are formed between two inner blocks 38C, 38D. The inner blocks 38C, 38D are inter-sipe blocks that are thinner than the outer blocks 38A, 38B, and the dimension (width) of the inner blocks 38C, 38D in the tire circumferential direction S is the dimension of the outer blocks 38A, 38B in the tire circumferential direction S. (width) smaller.

Lr is the depth in the tire radial direction K of the pair of adjacent sipes 23, Lt is the depth in the tire radial direction K of the central sipe 22, Lh is the depth in the tire radial direction K of the width direction groove 13, and the first circumferential groove Let the depth of 10 in the tire radial direction K be Ls (see FIG. 3). In this case, the pair of adjacent sipes 23 have the same depth Lr and are shallower than the central sipe 22 . That is, the depth Lr of the pair of adjacent sipes 23 is smaller than the depth Lt of the central sipe 22 (Lr<Lt). Further, the depth Lh of the width direction groove 13 is more than 1/2 and 3/4 or less of the depth Ls of the first circumferential direction groove 10 ((Ls×1/2)<Lh≦(Ls×3/ 4)). The depth Lt of the central sipe 22 is the same as the depth Lh of the widthwise groove 13 (Lt=Lh), and is more than 1/2 and 3/4 or less of the depth Ls of the first circumferential groove 10 ( (Ls×1/2)<Lt≦(Ls×3/4)). The depth Lr of the pair of adjacent sipes 23 is 1/2 or more of the depth Ls of the first circumferential groove 10 and smaller than the depth Lt of the central sipe 22 ((Ls×1/2)≦Lr <Lt).

Let Tf be the distance in the tire circumferential direction S between the central sipe 22 and the adjacent sipe 23 , and Tg be the distance in the tire circumferential direction S between the end wall 36 and the adjacent sipe 23 closer to the end wall 36 . The distance Tf is the distance in the tire circumferential direction S between the central sipe 22 and one adjacent sipe 23 and the distance in the tire circumferential direction S between the central sipe 22 and the other adjacent sipe 23 . The distance Tg is the distance in the tire circumferential direction S between the one end wall 36 and the adjacent sipe 23 closer to the one end wall 36 (one adjacent sipe 23), and the distance between the other end wall 36 and the other end wall 36. is the distance in the tire circumferential direction S of the adjacent sipe 23 closer to (the other adjacent sipe 23).

In this case, the distance Tf between the central sipe 22 and the adjacent sipe 23 is 1/3 or more and 1/2 or less of the depth Lr of the adjacent sipe 23 ((Lr×1/3)≦Tf≦(Lr×1/ 2)). A distance Tg between the end wall 36 and the adjacent sipe 23 is equal to or greater than the depth Lr of the adjacent sipe 23 (Lr≦Tg). Here (see FIG. 2), the distance Tg between the end wall 36 and the adjacent sipe 23 varies depending on the position of the block 31 in the tire width direction H, but is greater than or equal to the depth Lr of the adjacent sipe 23 throughout the block 31. . Further, even when the distance Tf between the central sipe 22 and the adjacent sipe 23 changes depending on the position of the block 31 in the tire width direction H, the distance Tf is in the range of 1/3 or more and 1/2 or less of the depth Lr of the adjacent sipe 23. is the distance within

FIG. 4 is a side view showing the state of the block 31 of the first embodiment when grounded, and schematically shows the block 31 as viewed from the side in the tire width direction H. As shown in FIG.
As shown in the figure, when the vehicle is running, the tire 1 rotates in the tire rotation direction R, and the block tread surface 34 of the block 31 comes into contact with the road surface G (ice road surface). As a result, the block tread 34 is pressed against the road surface G, and the block 31 is deformed. A plurality of edge portions are formed on the block tread surface 34 by the central sipe 22 and the pair of adjacent sipes 23 . A plurality of edge portions of the block tread surface 34 are edge components of the block 31 in the tire width direction H, and are pressed against the road surface G to exert an edge effect.

The two outer blocks 38A, 38B are deformed so as to protrude toward the inner blocks 38C, 38D and the width direction groove 13. The two inner blocks 38C, 38D are sandwiched between the two outer blocks 38A, 38B, pressed against the road surface G, and compressed inward in the tire radial direction K. This deforms the two inner blocks 38C, 38D so as to buckle between the two outer blocks 38A, 38B. Along with this, the two inner blocks 38C and 38D contact each other and the outer blocks 38A and 38B, respectively.

On the front side in the tire rotation direction R (rear side in the traveling direction of the vehicle) of the central sipe 22, the first inner block 38C is supported by the first outer block 38A and is positioned in the tire rotation direction R by the first outer block 38A. is pushed to the rear side (forward side in the traveling direction of the vehicle). On the rear side in the tire rotation direction R of the central sipe 22, the second inner block 38D pushes the second outer block 38B rearward in the tire rotation direction R while being supported by the first inner block 38C (see arrow J). ). The second inner block 38D pushes the second outer block 38B obliquely upward and applies a force (moment) to the second outer block 38B in the direction of pressing against the road surface G (see arrow M). As a result, the edge portion 38E of the second outer block 38B is pressed against the road surface G, and the ground pressure (edge pressure) at the edge portion 38E increases.

The second outer block 38B is a partition block on the kicking side of the block 31, and the edge portion 38E is a stepping edge portion positioned at the stepping end of the second outer block 38B. Here, the central sipe 22 is deeper than the pair of adjacent sipes 23, thus ensuring that the two inner blocks 38C, 38D deform on either side of the central sipe 22. Therefore, a moment is reliably generated in the second outer block 38B, and the ground contact pressure of the edge portion 38E increases. As a result, the edge effect of the edge portion 38E is improved, and the on-ice performance of the tire 1 is further improved.

FIG. 5 is a side view showing the blocks 31 and 100 in a state where a part of them is separated from the road surface G, and exaggerates the shapes of the sipes 22, 23 and 101. As shown in FIG. FIG. 5A shows an example of a conventional block 100 with two sipes 101 and FIG. 5B shows block 31 of the first embodiment.
As illustrated, when the blocks 31, 100 are grounded, the sipes 22, 23, 101 are deformed as the blocks 31, 100 are deformed, and the bottom portions of the sipes 22, 23, 101 are distorted. In block 31 of the first embodiment, strain is distributed to central sipe 22 and a pair of adjacent sipes 23 . Therefore, even if the central sipe 22 is deeper than the sipe 101 of the conventional block 100, the distortion of the bottoms of the sipes 22 and 23 is reduced, and the block 31 is prevented from being damaged.

Therefore, in the tire 1 of the first embodiment, it is possible to improve the on-ice performance of the tire 1 while suppressing damage to the blocks 31 . In addition, both the chipping resistance performance of the block 31 and the performance on ice of the tire 1 can be improved to achieve both. It is possible to deepen the central sipe 22, and even when the wear of the block 31 progresses, the edge component in the tire width direction H can be secured. As a result, the usage period of the tire 1 can be lengthened.

If the depth Lh of the widthwise groove 13 is less than half the depth Ls of the first circumferential groove 10, the service life of the tire 1 may be affected. On the other hand, if the depth Lh of the width direction groove 13 is larger than 3/4 of the depth Ls of the first circumferential direction groove 10, the chipping resistance performance of the block 31 may be affected. Therefore, the depth Lh of the widthwise groove 13 is preferably more than 1/2 and 3/4 or less of the depth Ls of the first circumferential groove 10 . In this case, it is possible to more reliably suppress damage to the blocks 31 while ensuring the service life of the tire 1 . By setting the depth Lt of the central sipe 22 to be the same as the depth Lh of the widthwise groove 13 , it is possible to ensure the service life of the tire 1 and to more reliably suppress damage to the blocks 31 . Therefore, even when the wear of the blocks 31 progresses, the performance on ice of the tire 1 can be ensured.

If the depth Lr of the pair of adjacent sipes 23 is smaller than half the depth Ls of the first circumferential groove 10, the service life of the tire 1 may be affected. On the other hand, if the depth Lr of the pair of adjacent sipes 23 is greater than or equal to the depth Lt of the central sipe 22, there is a risk that the fracture resistance performance of the inner blocks 38C and 38D will be affected. Therefore, the depth Lr of the pair of adjacent sipes 23 is preferably half or more the depth Ls of the first circumferential groove 10 and smaller than the depth Lt of the central sipe 22 . In this case, it is possible to more reliably suppress damage to the blocks 31 while ensuring the service life of the tire 1 .

If the distance Tf between the central sipe 22 and the adjacent sipes 23 is smaller than 1/3 of the depth Lr of the adjacent sipes 23, there is a risk that the fracture resistance performance of the inner blocks 38C and 38D will be affected. On the other hand, if the distance Tf between the central sipe 22 and the adjacent sipes 23 is larger than 1/2 of the depth Lr of the adjacent sipes 23, the inner blocks 38C and 38D may become difficult to deform. Therefore, the distance Tf between the central sipe 22 and the adjacent sipe 23 is preferably ⅓ or more and ½ or less of the depth Lr of the adjacent sipe 23 . In this case, while suppressing damage to the inner blocks 38C and 38D, the deformation of the second inner block 38D can more reliably increase the contact pressure of the edge portion 38E. When the distance Tg between the end wall 36 and the adjacent sipe 23 is equal to or greater than the depth Lr of the adjacent sipe 23, the plurality of sipes 22 and 23 are concentrated on the block central portion 33 side, so that the on-ice performance of the tire 1 is effectively improved. improves.

(Second embodiment)
Next, regarding the tire 1 of the second embodiment, the differences from the tire 1 of the first embodiment (see FIG. 1) will be described. Regarding the tire 1 of the second embodiment, the same names and symbols as the tire 1 of the first embodiment are used for the parts corresponding to the tire 1 of the first embodiment, and the same items as the tire 1 of the first embodiment are explained. are omitted. Also, the blocks 31 of the first land portion 30 and the blocks 41 of the second land portion 40 are similarly formed and have the same features with respect to their walls (side walls 35, end walls 36). Hereinafter, the block 31 will be described in detail by taking the block 31 of the first land portion 30 as an example. The block 41 of the second land portion 40 is the same as the block 31 of the first land portion 30, which will be described below, so description thereof will be omitted.

FIG. 6 is a perspective view showing blocks 31 of the second embodiment, and shows one block 31 as seen from the outside in the tire radial direction K. As shown in FIG. 6 shows the portion of the block 31 on the side of the first circumferential groove 10, and the portion of the block 31 on the side of the split sipes 20 and 21 is omitted.
As shown, the sidewall angle P of the block 31 varies between the block midsection 33 and the end walls 36 and the end wall angle Q of the block 31 is constant across the end walls 36 . Here, the angle related to the block 31 is the angle (intersecting angle) (unit:°) of the tire 1 in a prescribed state not on the ground. The specified state is a state in which the tire 1 is mounted on a specified rim, filled with a specified internal pressure, and unloaded.

For example, in the JATMA YEAR BOOK (Japan Automobile Tire Manufacturers Association standard), the specified rim is a standard rim, and the specified internal pressure is the air pressure specified corresponding to the maximum load capacity. When other standards are applied at the place of use or manufacture of the tire 1, the specified conditions of the tire 1 are defined according to each standard. Other standards are, for example, YEAR BOOK of TRA (The Tire and Rim Association Inc.) in the United States and STANDARDS MANUAL of ETRTO (The European Tire and Rim Technical Organization) in Europe. Here, the depth and distance in the first embodiment are also measured under the same conditions as the angle.

FIG. 7 is a cross-sectional view of the block 31 of the second embodiment, showing cross sections of each part of the block 31. As shown in FIG. 7A shows the side wall 35 of the block central portion 33 cut along the line X1-X1 of FIG. 6, and FIG. 7B shows the side wall 35 cut along the line X2-X2 of FIG. FIG. 7C shows an end wall 36 of block 31 cut along line X3-X3 of FIG.
As shown in FIGS. 6 and 7, the angles P and Q are defined based on the tire radial planes (the first tire radial plane K1 and the second tire radial plane K2) including the tire radial direction K, respectively. . The first tire radial plane K1 is a reference plane for the side wall angle P passing through the first edge portion 37A between the block tread 34 and the side wall 35, and the side wall angle P of the block 31 is the first tire radial plane K1. It is the angle formed with the side wall 35 . The second tire radial plane K2 is a reference plane for the end wall angle Q passing through the second edge portion 37B between the block tread surface 34 and the end wall 36, and the end wall angle Q of the block 31 is the second tire radial direction plane. It is the angle formed by the plane K2 and the end wall 36 .

The sidewall 35 of the block 31 is formed along the tire radial direction K, or extends in the tire radial direction K when viewed from the outside (block tread 34 side) toward the inside (groove bottom side) in the tire radial direction K. On the other hand, it is inclined inward in the groove width direction of the first circumferential groove 10 (toward the outside of the block 31). Specifically, the side wall angle P of the block 31 increases from the block central portion 33 (see FIG. 7A) toward the end walls 36 (see FIG. 7B) on both sides in the tire circumferential direction S. In addition, in the side wall 35 of the block 31 , the minimum portion with the smallest side wall angle P is provided at the block central portion 33 , and the maximum portion with the largest side wall angle P is provided at the end of the side wall 35 in the circumferential direction. The circumferential end of the side wall 35 is the end of the side wall 35 in the tire circumferential direction S (the end on the end wall 36 side). Further, the outer edge 35A of the side wall 35 at the block central portion 33 is the minimum portion of the side wall angle P. Thus, sidewall angle P of block 31 is smallest at outer edge 35A of sidewall 35 and increases progressively from outer edge 35A toward end wall 36. As shown in FIG.

Here, the side wall angle P of the block 31 is 0 degrees or more and 12 degrees or less (0 degrees ≤ P ≤ 12 degrees). The sidewall angle P is 0 degrees at the block central portion 33 (outer end 35A, which is the minimum portion), and 12 degrees at the circumferential end (maximum portion) of the sidewall 35 . The sidewall 35 is formed along the tire radial direction K in the portion where the sidewall angle P is 0 degrees (see FIG. 7A). In a portion where the side wall angle P is greater than 0 degrees (see FIG. 7B), the side wall 35 is the groove of the first circumferential groove 10 with respect to the tire radial direction K when viewed from the outside to the inside in the tire radial direction K. It is slanted inward in the width direction. The sidewall angle P of block 31 is the same angle (here, 12 degrees) at both circumferential ends of sidewall 35 .

The side wall angle P of block 31 increases continuously from block center 33 toward end wall 36 (see FIG. 6). As a result, the side wall 35 of the block 31 is formed with two wall surfaces 35B and 35C. The two wall surfaces 35B and 35C are formed on both sides of the outer end 35A in the tire circumferential direction S so as to face in different directions, and are connected at the outer end 35A of the side wall 35 . The angle E between the block tread 34 and the side wall 35 of the block 31 is 90 degrees or more (see FIGS. 7A and 7B), and gradually increases from the block central portion 33 toward the end wall 36 .

The end wall angle Q of the block 31 is the same as the side wall angle P of the block 31 at the circumferential end of the side wall 35 located on the end wall 36 side (see FIG. 7C). Therefore, the end wall 36 of the block 31 is located inside the widthwise groove 13 in the tire radial direction K (on the outside of the block 31) when viewed from the outside in the tire radial direction K toward the inside. Inclined. Also, the end wall angle Q of the block 31 is greater than 0 degrees and less than or equal to 12 degrees, and is 12 degrees corresponding to the side wall angle P here. The angle F formed between the block tread 34 of the block 31 and the end wall 36 is greater than 90 degrees and is the same as the angle E formed between the block tread 34 and the side wall 35 at the circumferential end of the side wall 35 .

FIG. 8 is a cross-sectional view showing the state of the block 31 of the present embodiment when it is grounded, and shows cross-sections of each part of the block 31 when the tire 1 is rolling (while the vehicle is running). In FIG. 8, the solid line indicates the shape of the block 31 that is deformed by the ground, and the broken line indicates the shape of the block 31 that is not deformed. 8A shows the side wall 35 of the block central portion 33 corresponding to FIG. 7A, and FIG. 8B shows the side wall 35 corresponding to FIG. 7B. 8A and 8B show part of the first circumferential groove 10 positioned between the first land portion 30 and the second land portion 40 (see FIG. 1). FIG. 8C shows the end wall 36 of the block 31 corresponding to FIG. 7C. FIG. 8C shows end walls 36 located on both sides of the widthwise groove 13 .

As shown in the figure, when the vehicle is running, as the tire 1 rotates, the block tread 34 of the block 31 comes into contact with the road surface G (icy road surface). As a result, the block tread 34 is pressed against the road surface G, and the block 31 is deformed. At the block central portion 33 (see FIG. 8A), the side wall angle P of the block 31 is relatively small, so the side wall 35 of the block 31 is deformed so as to protrude along the road surface G (see arrow N1). On the other hand, as the sidewall angle P of the block 31 increases (see FIG. 8B), the projection direction of the sidewall 35 inclines toward the road surface G, and the sidewall 35 of the block 31 deforms so as to project toward the road surface G (arrow See N2). In the end wall 36 (see FIG. 8C), the projecting direction of the end wall 36 is inclined toward the road surface G, and the end wall 36 of the block 31 is deformed so as to project toward the road surface G (see arrow N3).

As a result, the ground pressure increases from the block central portion 33 toward the end wall 36 at the first edge portion 37A (and its peripheral portion) on the side wall 35 side of the block 31 . As a result, the ground contact pressure is suppressed from increasing at the first edge portion 37A of the block central portion 33 and the ends of the sipes 22 and 23, avoiding concentration of the contact pressure and preventing damage to the block 31. suppressed from occurring. Further, the ground contact area at the block central portion 33, the length of the central sipe 22, and the edge component in the tire width direction H by the central sipe 22 are ensured. At the second edge portion 37</b>B on the end wall 36 side of the block 31 , the ground pressure is increased, so water is suppressed from entering toward the block central portion 33 .

Therefore, in the tire 1 of the second embodiment, it is possible to further improve the on-ice performance of the tire 1 while suppressing damage to the blocks 31 . In addition, both the chipping resistance performance of the block 31 and the performance on ice of the tire 1 can be improved to achieve both. When the side wall angle P of the block 31 increases from the outer end 35A in the block central portion 33 toward the end wall 36, the concentration of the ground contact pressure at the outer end 35A is avoided, and breakage of the block 31 is more reliably suppressed. be able to. By forming the plurality of sipes 22 and 23 in the block 31, the ice performance of the block 31 can be further improved.

Side wall angle P of block 31 increases continuously from block center 33 toward end wall 36 . As a result, the ground pressure continuously changes at the first edge portion 37A of the block 31, and the ground pressure is easily dispersed. When the end wall angle Q of the block 31 is the same as the side wall angle P of the block 31 at the circumferential end of the side wall 35, the ground pressure of the second edge portion 37B of the block 31 is the same throughout the second edge portion 37B. to more reliably suppress the intrusion of water toward the block central portion 33 .

The side wall 35 of the block 31 is inclined outward in the groove width direction of the first circumferential groove 10 (toward the inside of the block 31) with respect to the tire radial direction K when viewed from the outside in the tire radial direction K toward the inside. The side wall angle P of the block 31 is assumed to be less than 0 degrees when In this case, shear deformation increases at the first edge portion 37</b>A of the block 31 , which may affect the chipping resistance performance of the block 31 . Also, if the side wall angle P of the block 31 is larger than 12 degrees, there is a possibility that the shape of the first circumferential groove 10 including the shape of the groove bottom will be affected. Therefore, the side wall angle P of the block 31 is preferably 0 degrees or more and 12 degrees or less. In this case, it is possible to prevent the shape of the first circumferential groove 10 from being affected, and prevent the block 31 from being chipped.

Note that the side wall angle P of the block central portion 33 may be larger than 0 degrees. Moreover, the side wall angle P of the block 31 may be increased continuously, or the side wall angle P of the block 31 may be increased discontinuously. The end wall angle Q of the block 31 may be different from the side wall angle P at the circumferential ends of the side walls 35 . The sidewall 35 of the second embodiment may be applied to one sidewall of the block 31 in the tire width direction H, or may be applied to both sidewalls of the block 31 in the tire width direction H.

A block similar to the block 31 of the first embodiment or the second embodiment may be provided on one land portion of the tread portion 2 or may be provided on a plurality of land portions of the tread portion 2 . Blocks 31 can be applied to various tread patterns with blocks.

(Third embodiment)
FIG. 9 is a plan view showing the tread pattern of the tire 1 of the third embodiment, and schematically shows a portion of the tread portion 2 in the tire circumferential direction S. As shown in FIG.
Here, the widthwise grooves 15 of the third land portion 50 are different from the widthwise grooves 15 of the third land portion 50 shown in FIG. The widthwise groove 15 is a narrow groove similar to the narrow groove 52 of the block 51 and is narrower than the circumferential grooves 10 and 11 and the other widthwise grooves 13 and 14 .

DESCRIPTION OF SYMBOLS 1... Tire, 2... Tread part, 3... Tire equatorial surface, 4... Shoulder part, 10... First circumferential groove, 11... Second circumferential groove, 13. ... width direction groove, 14 ... width direction groove, 15 ... width direction groove, 20 ... divided sipe, 21 ... divided sipe, 22 ... central sipe, 23 ... adjacent sipe, 24... Split sipe, 25... Split sipe, 26... Central sipe, 27... Adjacent sipe, 30... First land portion, 31... Block, 32... Central line, 33... Block center part, 34... Block tread, 35... Side wall, 36... End wall, 40... Second land part, 41... Block, 42... Center line, 43... Block central part, 50... Third land part, 51... Block, 52... Thin groove, 53... Sipe, G... Road surface, H... Tire width direction, K... Tire radial direction, P... Side wall angle, Q... End wall angle, R... Tire rotation direction, S... Tire circumferential direction.

Claims (5)

A tire having blocks in the tread,
The block has a central sipe formed along the tire width direction on the block tread surface at the center of the block in the tire circumferential direction, and a block tread surface formed along the tire width direction adjacent to both sides of the central sipe in the tire circumferential direction. a pair of adjacent sipes;
The tire radial depth of the pair of adjacent sipes is smaller than the tire radial depth of the central sipe,
A tire in which a circumferential distance between an end wall of a block and an adjacent sipe closer to the end wall in the tire circumferential direction is greater than or equal to the depth of the adjacent sipe in the tire radial direction . A tire having blocks in the tread,
The block has a central sipe formed along the tire width direction on the block tread surface at the center of the block in the tire circumferential direction, and a block tread surface formed along the tire width direction adjacent to both sides of the central sipe in the tire circumferential direction. a pair of adjacent sipes and side walls extending along the tire circumferential direction between end walls on both sides in the tire circumferential direction ,
The tire radial depth of the pair of adjacent sipes is smaller than the tire radial depth of the central sipe,
A tire in which the side wall angle formed by the tire radial direction surface and the side wall of the block increases from the center of the block toward the end wall . In the tire according to claim 1 or 2 ,
Circumferential grooves extending along the tire circumferential direction partitioning the blocks, and width direction grooves extending along the tire width direction partitioning the blocks,
The depth of the width direction groove in the tire radial direction is more than 1/2 and 3/4 or less of the depth of the circumferential groove in the tire radial direction,
A tire in which the radial depth of the central sipe is the same as the radial depth of the transverse grooves. In the tire according to claim 3 ,
A tire in which a pair of adjacent sipes have a tire radial depth that is equal to or more than half the tire radial depth of a circumferential groove and smaller than the tire radial depth of a central sipe. In the tire according to any one of claims 1 to 4 ,
A tire in which the distance in the tire circumferential direction between the central sipe and adjacent sipes is 1/3 or more and 1/2 or less of the depth of the adjacent sipes in the tire radial direction.

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