JP5388118B2 - tire - Google Patents

Description

  The present invention relates to a tire in which a land portion composed of a plurality of blocks is defined in a tread portion, and a plurality of sipes are arranged in the block.

  In large-sized studless tires for trucks and buses, it is important to improve the performance on ice and snow (for example, traction performance and braking performance on ice and snow) to ensure safety on the road surface in winter. Therefore, conventionally, the number of blocks in the ground tread and the number of sipes (open sipes) that open at both ends in the block are increased to increase the edge component, enhancing the edge effect and improving performance on ice and snow. Improvements are being made.

  However, as the number of blocks and sipes increases, the rigidity of each block decreases and wear resistance decreases, or the rigidity of small blocks partitioned by sipes decreases and the block durability tends to decrease. Therefore, simply increasing the number of blocks and sipes cannot achieve both performance on ice and snow and other performance, and it is difficult to secure sufficient required performance for each. In addition, as the sipe increases, the block rigidity decreases, resulting in greater collapse of the block when touching, and the desired edge effect is not exhibited, or the contact area is reduced, affecting the performance on ice and snow. May occur.

On the other hand, conventionally, a pneumatic tire that has improved performance on ice and snow while maintaining wear resistance by, for example, forming two widthwise sipes extending linearly in the tire width direction on the tread block. Is known (see Patent Document 1).
However, in this conventional tire, the amount of the edge component effective in running on ice and snow is still insufficient, and further improvement in performance on ice and snow is demanded while ensuring wear resistance and block durability.

JP 2007-186121 A

  The present invention has been made in view of such a conventional problem, and its purpose is to secure sufficient wear resistance and block durability to a tire having a block in a land portion of a tread portion, This is to improve the performance of tires on ice and snow.

The present invention is a tire in which a tread portion includes a plurality of circumferential grooves extending in the tire circumferential direction and a land portion partitioned by the circumferential groove, and the land portion is partitioned into a plurality of blocks, each block In addition, two width-direction sipes that divide the block in the tire circumferential direction and divide the block into three small blocks, and a pair that is positioned at both ends in the tire circumferential direction and wider in the tire circumferential direction than the other small blocks a wide small block, wide small blocks in each extend to one placed tire width direction possess a closed sipes of three-dimensional shape that both ends are closed, a plurality of blocks of the land portion, the tire circumferential direction There are a plurality of block pairs consisting of a pair of blocks adjacent to each other across the circumferential sipe extending in the tire width direction, and six edges consisting of the width sipe, closed sipe, and both ends of the tire circumferential direction of each block Element is, at block adjacent in the tire width direction, characterized that you have been placed together tire circumferential positions.

  ADVANTAGE OF THE INVENTION According to this invention, the on-ice performance of a tire can be improved, ensuring sufficient abrasion resistance and block durability for the tire which has a block in the land part of a tread part.

It is a top view which expands and shows the tread pattern of the tire of this embodiment. It is a top view which expands and shows one block pair of a central land part. It is sectional drawing which looked at the width direction sipe of the block from the center side circumferential groove side. It is a perspective view which shows a part of closed sipe of a block. It is a top view which expands and shows the tread pattern of the conventional tire.

Hereinafter, an embodiment of a tire of the present invention will be described with reference to the drawings.
The tire of this embodiment is a studless tire for heavy loads such as trucks and buses and passenger cars, for example. In the following, a pneumatic tire will be described as an example, but other tires such as a tire filled with a gas other than air will be described. It may be a tire. The tire also includes a bead core disposed in the pair of bead portions, a carcass extending between the bead portions, a belt disposed on the outer peripheral side of the carcass in the tread portion, and a tread rubber on which a predetermined tread pattern is formed. Etc., having a well-known tire structure.

FIG. 1 is a plan view showing a developed tread pattern of a tire according to the present embodiment, and schematically shows a part in the tire circumferential direction (the arrow R direction in the figure).
As shown in the drawing, the tire 1 includes a plurality of circumferential grooves 10 and 11 extending in the tire circumferential direction and a plurality of land portions 20, 21, and 22 extending in the tire circumferential direction partitioned by the tread portion 2. I have. In addition, the tire 1 is linearly arranged in a direction intersecting with the circumferential grooves 10 and 11 disposed in the land portions 20, 21, and 22, for example, a tire width direction (arrow W direction in the drawing), or inclined or curved. A plurality of lug grooves 30, 31, 40, 41, 50 extending equally are provided. The tire 1 is divided into a plurality of blocks 20B, 21B, and 22B in which the land portions 20, 21, and 22 are divided by the plurality of lug grooves 30, 31, 40, 41, and 50 and arranged in the tire circumferential direction. Has been.

  The circumferential grooves 10, 11 are arranged in the tread portion 2 with at least two (here, four), two central circumferential grooves 10 arranged with the tire equatorial plane CL interposed therebetween, and the tire width direction thereof. It consists of two outer circumferential grooves 11 respectively arranged on the outer tread end (tire width direction outer end) side. The circumferential grooves 10 and 11 are straight grooves extending linearly in the tire circumferential direction, and the groove width and the depth in the tire radial direction are the same (or similar), and each tire equatorial plane CL Are arranged at symmetrical positions in the tire width direction.

  The land portions 20, 21, 22 are located in an intermediate region defined by the central land portion 20 and the circumferential grooves 10, 11 positioned on the tire equator plane CL defined by the two central circumferential grooves 10. It consists of two middle land parts 21 and two shoulder land parts 22 located in the tire width direction outermost side (shoulder part side). Of these five rows, the central land portion 20 and the intermediate land portion 21 are partitioned by the circumferential grooves 10 and 11 on both sides in the tire width direction, whereas the shoulder land portion 22 has only one outer side circumference. It is divided by the direction groove | channel 11, and is arrange | positioned between tread ends. Further, the width in the tire width direction of each land portion 20, 21, 22 is formed to a width according to the arrangement position of the circumferential grooves 10, 11 that divide them, and here, the central land portion 20 and the intermediate land portion 21 is formed in the same width.

  In addition, the central land portion 20 includes a plurality of first lug grooves 30 and second lug grooves 31 extending in the tire width direction, circumferential sipes 32 and 33 extending in the tire circumferential direction, and in the tire width direction. The extending sipes 34 and 35 are repeatedly arranged in a predetermined pattern in the tire circumferential direction.

  The first and second lug grooves 30 and 31 have one end opened in each of the central circumferential grooves 10 on both sides (in the figure, the first lug groove 30 is on the left side and the second lug groove 31 is on the right center. The other end terminates at the central portion (on the tire equatorial plane CL or in the vicinity thereof) in the central land portion 20. In addition, the plurality of first lug grooves 30 and second lug grooves 31 are spaced at the same interval in the tire circumferential direction and spaced apart from each other in the tire circumferential direction, and the arrangement positions (phases) are arranged in the tire circumferential direction. They are shifted and arranged alternately along the tire circumferential direction.

  In the tire 1, the first and second lug grooves 30, 31 are formed in a straight line inclined in the same direction with respect to the tire width direction and at a predetermined angle from the tire width direction. Further, the first and second intervals are repeated so that the interval between the first lug groove 30 and the second lug groove 31 adjacent in the tire circumferential direction is alternately narrow and wide along the tire circumferential direction. The lug grooves 30 and 31 are sequentially arranged. Furthermore, circumferential sipes 32 and 33 alternately arranged along the tire circumferential direction are opened at the respective end portions of the first lug groove 30 and the second lug groove 31.

  These circumferential sipes 32 and 33 are formed in the central portion of the central land portion 20 in the tire width direction (on the tire equatorial plane CL) and between the first and second lug grooves 30 and 31 adjacent in the tire circumferential direction. Arranged in order, the central land portion 20 is divided into two block rows by dividing the central land portion 20 in the tire width direction. One circumferential sipe 32 is provided on the side where the gap between the lug grooves 30 and 31 is wide, and also functions as a boundary between the blocks 20B adjacent in the tire width direction. The circumferential sipe 32 has a zigzag shape, a wave shape, or a meandering bent shape, and is bent at least once and extends in the tire circumferential direction, and is open to the lug grooves 30 and 31. On the other hand, the other circumferential sipe 33 is provided on the side where the gap between the lug grooves 30 and 31 is narrow, and functions as a connecting sipe for connecting the first and second lug grooves 30 and 31 to each other. Have. The circumferential sipe 33 extends linearly in the tire circumferential direction or inclined or curved (inclined here) at a predetermined angle, and opens to and connects the lug grooves 30, 31. 31 and the central land portion 20 are traversed in the tire width direction as a whole.

  In the present embodiment, a plurality of sets of the circumferential sipe 33 and a pair of first and second lug grooves 30 and 31 connected to each other are arranged at a predetermined interval in the tire circumferential direction, and the central land portion 20 is a tire. Divide in the circumferential direction. In addition, the divided central land portion 20 is divided in the tire width direction by a circumferential sipe 32 that is bent and extended in the tire circumferential direction, and the central land portion 20 is partitioned into a plurality of blocks 20B having a substantially rectangular shape in plan view. Thereby, a plurality of blocks 20B are alternately arranged across the tire equatorial plane CL, and a plurality of blocks 20B are arranged in the tire circumferential direction on both sides of the central land portion 20 across the tire equatorial plane CL. Forming a column. Further, a pair of blocks 20B adjacent to each other in the tire width direction with the circumferential sipe 32 interposed therebetween are arranged shifted in the tire circumferential direction, and a plurality of block pairs including the pair of blocks 20B are arranged in the tire circumferential direction, The unit 20 and a plurality of blocks 20B are configured.

  In FIG. 1, one block pair of the central land portion 20 is hatched with diagonal lines, and the pair of blocks 20B are hatched with diagonal lines inclined in opposite directions. Further, in the central land portion 20, the plurality of block pairs are sequentially arranged in the tire circumferential direction with a part of them adjacent to each other with a sipe (here, the circumferential sipe 33) interposed therebetween.

FIG. 2 is an enlarged plan view showing a range including one block pair of the central land portion 20.
As shown in the figure, the tire 1 is divided into each block 20B, a width-direction sipe 34 that divides the block 20B in the tire circumferential direction and divides the block 20B into at least three small blocks 20S and 20T, and both sides in the tire circumferential direction across the blocks. The closed sipe 35 is provided.

  The width-direction sipe 34 is a both-end opening sipe whose both ends open to the circumferential sipe 32 and the center-side circumferential groove 10 that define each block 20B, and is linear or inclined or curved in the tire width direction. Extending across the block 20B. Here, at least two (in this case, two) width-direction sipes 34 are arranged on the center side in the tire circumferential direction of the block 20B, and they are inclined in the same direction with respect to the tire width direction and spaced apart from each other by a predetermined distance. Open and formed. The blocks 20B are narrow-width blocks 20T having a narrow width in the tire circumferential direction located in the middle portion in the tire circumferential direction between the sipe 34 in the width direction, and the inner and other blocks 20B. Are divided into a pair of wide and small blocks 20S that are wider in the tire circumferential direction than the small blocks (the narrow and narrow blocks 20T).

  At least one (here, one) closed sipe 35 is disposed in each of the wide and small blocks 20S, and is formed at the center in the tire circumferential direction between the widthwise sipes 34 and the lug grooves 30 or 31 on both sides thereof. Has been. Further, the closed sipe 35 is bent one or more times and extends in the tire width direction as a whole, both ends do not open in the central circumferential groove 10 and the like, and terminate and close in the wide block 20S, which will be described later. In this way, the shape is formed in a three-dimensional shape that changes three-dimensionally in the wide and small block 20S.

  Here, both blocks 20B of the block pair are arranged in a position shifted in the tire circumferential direction, and the narrow block sandwiched between the tire circumferential direction position of the closed sipe 35 on one end side and the opposite wide block 20S. The tires are arranged together with the 20T tire circumferential direction position. In addition, six edge elements composed of the four sipes 34 and 35 of each block 20B and both ends (edges) in the tire circumferential direction are arranged with the tire circumferential direction positions aligned with each other in the block 20B adjacent in the tire width direction. Has been. Thereby, each edge component in the central land part 20 is provided at equal intervals by matching the phase in the tire circumferential direction. In addition, the depth in the tire radial direction of all the sipes 32 to 35 is formed to be more than half (50 to 100%) of the depth in the tire radial direction of the circumferential grooves 10 and 11, The sipes 34 and 35 in the block 20B are formed in different shapes.

FIG. 3 is a cross-sectional view of the width direction sipe 34 of the block 20B as viewed from the central circumferential groove 10 side.
As shown in the figure, the width direction sipe 34 has an end portion on the inner side in the tire radial direction swelled in a circular cross section with respect to the slit-shaped (thin groove-shaped) tread surface T with parallel wall surfaces, and a bottom 34A in the depth direction. The cross-sectional flask shape is formed throughout.

FIG. 4 is a perspective view showing a part of the closed sipe 35 of the block 20 </ b> B, and schematically showing a part of one side of the opposing wall surface of the closed sipe 35.
As shown in the figure, the closed sipe 35 is bent at least once on the tread surface T of the block 20B and extends in a zigzag shape or a wave shape in the tire width direction (left-right direction in the figure), and in the depth direction (downward direction in the figure). ) Bend more than once. In the closed sipe 35, the bending in the tire width direction and the depth direction is repeated in the same manner over the entire wall surface. By combining the bending in both directions, the concavities and convexities that are symmetrical to each other are formed on the opposing wall surfaces. Sequentially formed at opposing positions. As described above, the closed sipe 35 is formed into a shape that changes three-dimensionally within the block 20B, in which a plurality of irregularities are provided on the wall surface (in the present invention, such a shape is referred to as a three-dimensional shape).

  With respect to the central land portion 20, the intermediate land portion 21 (see FIG. 1) on both outer sides in the tire width direction includes a plurality of lug grooves 40 and 41 extending in the tire width direction, and a circumferential sipe extending in the tire circumferential direction. 42 and 43 and sipes 44 and 45 extending in the tire width direction are repeatedly arranged in a predetermined pattern in the tire circumferential direction. The lug grooves 40, 41, the circumferential sipes 42, 43, and the sipes 44, 45 of the intermediate land portion 21 are the lug grooves 30, 31, the circumferential sipes 32, 33, and the sipes 34 of the central land portion 20, respectively. , 35.

  That is, the lug grooves 40 and 41 are arranged alternately on the left and right along the tire circumferential direction, with one end opening in each of the circumferential grooves 10 and 11 and the other end terminating in the center of the intermediate land portion 21. Yes. Circumferential sipes 42 and 43 are central portions in the tire width direction of the intermediate land portion 21 and are arranged in order between the lug grooves 40 and 41 adjacent to each other in the tire circumferential direction and open to the lug grooves 40 and 41, respectively. The land portion 21 is divided into two block rows by dividing the land portion 21 in the tire width direction. Further, one circumferential sipe 42 has a bent shape, is provided on the side where the gap between the lug grooves 40 and 41 is wide, and functions as a boundary between the blocks 21B adjacent in the tire width direction. On the other hand, the other circumferential sipe 43 is provided on the side where the gap between the lug grooves 40 and 41 is narrow, connects the lug grooves 40 and 41, and the intermediate land portion 21 as a whole together with the lug grooves 40 and 41. Is crossed in the tire width direction.

  The intermediate land portion 21 includes a plurality of circumferential sipe 43 and a pair of lug grooves 40 and 41 that are connected to each other, arranged in the tire circumferential direction, divided in the tire circumferential direction, and bent by a circumferential sipe 42 that is bent. Divided in the direction and partitioned into a plurality of blocks 21B. As a result, a plurality of blocks 21B are alternately arranged on the left and right along the tire circumferential direction, and block pairs (shown with hatching in the figure) including a pair of blocks 21B adjacent to each other across the circumferential sipe 42 in the tire width direction. ) Are formed. Further, in the intermediate land portion 21, the plurality of block pairs are sequentially arranged in the tire circumferential direction in such a manner that a part thereof is adjacent to each other with the circumferential sipe 43 interposed therebetween.

  Further, each block 21B has a plurality of (two in this case) width direction sipes that divide the block 21B in the tire circumferential direction and divide the block 21B into at least three small blocks 21S and 21T, as in the block 20B shown in FIG. 44 and closed sipes 45 provided on both sides in the tire circumferential direction are provided. The width direction sipe 44 is a sipe that is open at both ends, and the bottom in the depth direction is formed in a cross-sectional flask shape (see FIG. 3). In addition, the width direction sipe 44 includes the blocks 21B, which are positioned between the narrow and narrow blocks 21T having a narrow width in the tire circumferential direction and the tire circumferential direction than the other small blocks 21T that are positioned at both ends in the tire circumferential direction. It is divided into a pair of wide small blocks 21S having a wide width in the direction. The closed sipes 45 are respectively arranged in the wide and small blocks 21S, and are formed in a three-dimensional shape (see FIG. 4) that extends in the tire width direction while being bent, closes both ends, and changes in shape three-dimensionally. Yes.

  Thus, the intermediate land portion 21 is configured in the same manner as the central land portion 20, and both blocks 21B of the block pair are sandwiched between the tire circumferential direction position of the closed sipe 45 on one end side and the opposite wide small block 21S. The narrow and narrow blocks 21T are arranged together with the tire circumferential direction position. Further, six edge elements composed of the four sipes 44 and 45 of each block 21B and both ends (edges) in the tire circumferential direction are arranged so that the tire circumferential direction positions are aligned with each other in the block 21B adjacent in the tire width direction. Has been. In addition, all the sipes 42 to 45 are formed so that the depth in the tire radial direction is more than half (50 to 100%) of the depth in the tire radial direction of the circumferential grooves 10 and 11. Yes.

  On the other hand, the shoulder land portion 22 includes a plurality of lug grooves 50 extending in the tire width direction, circumferential narrow grooves 51 extending in the tire circumferential direction, and sipes 54 and 55 extending in the tire width direction in the tire circumferential direction. It is repeatedly arranged in a predetermined pattern. The shoulder land portion 22 includes a plurality of blocks 22B arranged in the tire circumferential direction along the outer circumferential groove 11 by the outer circumferential groove 11 and the circumferential narrow groove 51 and the lug grooves 50 opened at both ends thereof. It is partitioned. As in the block 20B shown in FIG. 2, each block 22B includes a plurality (two in this case) of widthwise sipes 54 that are divided into at least three small blocks 22S and 22T by dividing the block 22B in the tire circumferential direction. Closed sipes 55 provided on both sides in the tire circumferential direction are provided.

  The width direction sipe 54 and the closed sipe 55 are configured in the same manner as the width direction sipe 34 (see FIGS. 2 and 3) and the closed sipe 35 (see FIGS. 2 and 4), respectively. That is, the width direction sipe 54 is an open sipe at both ends, and the bottom in the depth direction is formed in a cross-sectional flask shape. In addition, the width direction sipe 54 is configured such that the block 22B includes a narrow width narrow block 22T having a narrow width in the tire circumferential direction at an intermediate portion, and a width in the tire circumferential direction as compared with the other small blocks 22T. Is divided into a pair of wide and small blocks 22S. The closed sipes 55 are respectively arranged in the wide and small blocks 22S, and are formed in a three-dimensional shape that extends in the tire width direction while being bent, closes both ends, and changes in shape three-dimensionally. Both sipes 54 and 55 are formed so that the depth in the tire radial direction is more than half (50 to 100%) of the depth in the tire radial direction of the circumferential grooves 10 and 11.

  As described above, the shoulder land portion 22 is different from the other land portions 20 and 21 having two block rows, and each block 22B having two width-direction sipes 54 and two closed sipes 55 is provided in the tire circumferential direction. Are provided with one row of block rows.

  As described above, in the tire 1 of the present embodiment, a plurality of the width direction sipes 34, 44, 54 and the closed sipes 35, 45, 55 are arranged in each block 20B, 21B, 22B. As a result, the number and length of sipes and edge components in the blocks 20B, 21B, and 22B can be increased, and the edge effect can be enhanced to improve the performance on ice and snow. Further, the blocks 20B, 21B, and 22B are divided into wide and small blocks 20S, 21S, and 22S on both ends and narrow blocks 20T, 21T, and 22T therebetween by the width direction sipes 34, 44, and 54. As a result, since the narrow blocks 20T, 21T, and 22T are supported by the wide blocks 20S, 21S, and 22S on both sides, a decrease in block rigidity due to the formation of the width direction sipes 34, 44, and 54 can be suppressed. At the same time, when rolling the tire, the narrow blocks 20T, 21T, and 22T are in contact with the road surface for a long time, and the effect of improving the performance on ice and snow is also obtained.

  Further, since the closed sipes 35, 45, and 55 are formed in the wide and small blocks 20S, 21S, and 22S having higher rigidity than the narrow and narrow blocks 20T, 21T, and 22T, the blocks 20B, 21B, and 22B are increased while increasing the edge components. It is possible to suppress a decrease in rigidity as a whole. At that time, the closed sipes 35, 45, and 55 are closed at both ends within the wide and small blocks 20S, 21S, and 22S, so that, for example, compared to when an open sipe is formed, the opening is less likely to occur during tire rolling. Is reduced. Along with this, a decrease in rigidity of each of the small blocks 20S, 21S, and 22S is suppressed, and sufficient block rigidity can be secured. In addition, since the closed sipes 35, 45, and 55 are formed in a three-dimensional shape, the effect of supporting the unevenness of the opposing wall surfaces to each other when an external force is exerted is exhibited. Compared with, block rigidity can be increased.

  Further, in the tire 1, since high block rigidity is obtained as described above, the performance on ice and snow can be improved without deteriorating wear resistance and block durability. In addition, since the collapse of the blocks 20B, 21B, and 22B at the time of ground contact can be suppressed, the expected edge effect can be exhibited, and the decrease in the contact surface area can also be suppressed, thereby preventing deterioration in performance on ice and snow. .

  Therefore, according to the present embodiment, the tire 1 having the blocks 20B, 21B, and 22B in the land portions 20, 21, and 22 of the tread portion 2 while ensuring sufficient wear resistance and block durability, the tire 1 The performance on ice and snow can be improved. Therefore, it is possible to achieve both the performance on ice and snow and other performances to obtain sufficient required performances, and to ensure the safety of the tire 1 on the road surface in winter. Moreover, in this tire 1, since the bottom part of the width direction sipe 34,44,54 in the depth direction was formed in the cross-sectional flask shape, it can relieve | strain that distortion concentrates on a sipe bottom, and can improve block durability.

  Here, it is preferable that the blocks 20B and 21B of the block pair described above are arranged such that the positions of the closed sipes 35 and 45 and the narrow blocks 20T and 21T in the tire circumferential direction are aligned with each other. By doing so, the rigidity of the land portions 20 and 21 including a plurality of pairs of blocks can be set such that the high rigidity range and the low rigidity range of both blocks 20B and 21B can be shifted in the tire circumferential direction and arranged alternately. It can be adjusted appropriately along the direction. Thereby, the rigidity change of the tire circumferential direction of the land parts 20 and 21 can be made small, and generation | occurrence | production of uneven wear can be suppressed further. In addition, as described above, by arranging a plurality of block pairs continuously in the tire circumferential direction while adjoining a part of each other across the sipe, the effect of mutually suppressing deformation and falling down is exhibited, The block rigidity can be made higher than when they are arranged independently.

  In the tire 1, the circumferential grooves 10 and 11 are formed as straight grooves extending linearly in the tire circumferential direction. However, these may be bent in a zigzag manner with amplitude in the tire width direction, for example. It may be formed so as to extend in the tire circumferential direction. However, if the circumferential grooves 10 and 11 are formed as straight grooves, the snow-removing property becomes higher and the performance on the snow and snow of the tire 1 can be further improved. Therefore, the circumferential grooves 10 and 11 are formed as such. Is more desirable.

(Tire test)
In order to confirm the effect of the present invention, the tire 1 of the example (hereinafter referred to as an example product) provided with the tread pattern (see FIG. 1) described above and the conventional example (comparative example) provided with the conventional tread pattern. A tire (hereinafter referred to as a conventional product) was prototyped and subjected to a comparative test of traction performance on ice, wear resistance and block durability under the following conditions. Both the actual product and the conventional product are radial ply tires for trucks and buses having a tire size of 11R22.5-16PR defined by JATMA YEAR BOOK (2009, Japan Automobile Tire Association Standard).

FIG. 5 is a plan view showing a developed tread pattern of a conventional product, and schematically shows a part in the tire circumferential direction.
In this test, as shown in the figure, the conventional product (tire 100) formed the land portions 20, 21, and 22 without providing the closed sipes 35, 45, and 55 with respect to the implemented product (see FIG. 1). The other configuration of the tread pattern was the same as that of the actual product.

  In the test, first, edge components and block rigidity per block formed in these practical products and conventional products were obtained, and then each actual vehicle test described later was performed. In the actual vehicle test, a new implementation product and a conventional product were mounted on a rim of size 7.50, the air pressure was set to 900 kPa, each was attached to a 2-D vehicle (tractor), and a normal load (maximum load capacity) was applied. Went in state. In the traction performance test on ice, on the test course (ice road surface), the vehicle was started from a stopped state and the acceleration was measured, and the measurement result was evaluated based on the conventional product. On the other hand, in the wear resistance test, the test course (dry road surface) was run under the same conditions, the wear life (lifetime) at that time was measured, and the measurement result was evaluated based on the conventional product. In the block durability test, a general road (dry road surface) was run under the same conditions, the block durability at that time was measured, and the measurement result was evaluated based on the conventional product.

  Table 1 shows the results of each of these tests and the like, all of which are expressed as an index with the conventional product as 100, and the larger the value, the better the characteristics and results and the higher the performance.

  As a result, as shown in Table 1, the edge component and block stiffness were 120 and 100 in the actual product, respectively, compared to 100 and 100 in the conventional product, and it was found that the edge component can be increased while maintaining the block stiffness. . The starting acceleration index was as large as 120 for the actual product compared to 100 for the conventional product, and it was found that the traction performance on ice was significantly improved and the performance on ice and snow could be improved. In addition, the wear life index and the block durability index are 100 and 100 in the actual product compared to 100 and 100 in the conventional product, and it was found that the wear resistance and the block durability can be maintained at the same level.

  From this, it was proved that the tire 1 having a block in the land portion of the tread portion 2 can improve the performance on the snow and snow of the tire 1 while ensuring sufficient wear resistance and block durability.

  DESCRIPTION OF SYMBOLS 1 ... Tire, 2 ... Tread part, 10 ... Center side circumferential groove, 11 ... Outer circumferential groove, 20 ... Central land part, 20B ... Block, 20S, 20T ..Small block, 21 ... Middle land, 21B ... Block, 21S, 21T ... Small block, 22 ... Shoulder land, 22B ... Block, 22S, 22T ... Small block , 30, 31 ... lug groove, 32, 33 ... circumferential sipe, 34 ... width sipe, 35 ... closed sipe, 40, 41 ... lug groove, 42, 43 ... Circumferential sipe, 44 ... Width sipe, 45 ... Closed sipe, 50 ... Lug groove, 51 ... Circumferential narrow groove, 54 ... Width sipe, 55 ... Closed sipe, CL: Tire equator surface, T: Tread surface.

Claims (4)

The tread portion includes a plurality of circumferential grooves extending in the tire circumferential direction and a land portion partitioned by the circumferential grooves, and the land portion is a tire partitioned into a plurality of blocks,
Each block, two in the width direction sipes of which partitioned into three small blocks by dividing the block in the tire circumferential direction, a width in the tire circumferential direction than the other small blocks located in the tire circumferential direction at both ends possess a broad and a pair of wide small block, and closed sipes of three-dimensional shape that both ends are closed extend each one arranged in the tire width direction wider small block, and
A plurality of blocks in the land portion have a plurality of block pairs each consisting of a pair of blocks adjacent to each other in the tire width direction across a circumferential sipe extending in the tire circumferential direction,
Widthwise sipes and closed sipes and the tire circumferential direction six consisting of the two ends of the edge elements of each block, the block adjacent in the tire width direction, and characterized that you have been placed together tire circumferential position to each other Tire. In the tire according to claim 1,
Closed sipes extending in the tire width direction is bent at least once at the tread surface of the block, and characterized that you also bent at least once in the depth direction the tire. In the tire according to claim 1 or 2,
A tire characterized in that a plurality of block pairs are continuously arranged in the tire circumferential direction while partly adjoining each other across a sipe. In the tire according to any one of claims 1 to 3,
The width-direction sipe is a tire characterized in that the inner end in the tire radial direction swells in a circular cross section with respect to the slit-shaped tread surface side .

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