JP2013032029A - Tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire capable of further preventing a decrease in the durability of a large block, even if increasing the number of widthwise sipes.SOLUTION: The large block 100 is divided into at least three middle blocks 20 by a plurality of widthwise sipes 60. The at least three middle blocks 20 includes edge blocks 30 arranged at both ends in the tire circumferential direction, and at least one central block 40 sandwiched between the edge blocks 30. In the tire circumferential direction, L2 being a length of the central block 40 is longer than L1 being a length of the edge block 30, and a tie bar 150 being in contact with the edge block 30 is arranged in the tire circumferential direction in a groove bottom of the width direction groove 300.

Description

  The present invention relates to a tire including a pair of bead cores and a carcass layer having a toroidal shape straddling between the pair of bead cores.

  Conventionally, a pair of bead cores, a carcass layer having a toroidal shape straddling between a pair of bead cores, a belt layer disposed adjacent to the carcass layer, and a bead core, a carcass layer, and a rubber layer covering the belt layer Tires equipped are known.

  The tire includes a bead portion having a bead core, a tread portion having a tire ground contact surface, a sidewall portion forming a side surface of the tire, and a shoulder portion provided across the sidewall portion and the tread portion.

  The tire ground contact surface is provided with a large block defined by a circumferential groove extending along the tire circumferential direction and a widthwise groove extending along the tread width direction. The large block is provided with a width direction sipe extending along the tread width direction.

  In addition, in order to improve the snow and snow performance while suppressing a decrease in the durability performance of the large block, it has been studied to increase the number of width direction sipes provided in the large block. For example, a technique for partitioning a large block into a plurality of middle blocks by a pair of width-direction sipes having a narrow interval has been proposed (for example, Patent Document 1). In addition, the site | part provided between a pair of width direction sipes may be called a small block.

JP 2008-120174 A

  However, in the above-described technique, although a certain effect can be obtained with respect to suppressing the decrease in the durability performance of the large block, further suppression of the decrease in the durability performance of the large block is desired.

  Therefore, the present invention has been made to solve the above-described problem, and even when the number of width-direction sipes is increased, it is possible to further suppress a decrease in durability performance of the large block. The object is to provide a tire.

  In order to solve the above-described problems, the present invention has the following features. A feature of the present invention is a tire including a tread portion having a tire contact surface, and the tire contact surface is partitioned by a circumferential groove extending along the tire circumferential direction and a width direction groove extending along the tread width direction. A large block is provided, and a plurality of width direction sipes extending along the tread width direction are provided on a ground contact surface of the large block, and the large block is formed by the plurality of width direction sipes. Divided into three or more middle blocks, the three or more middle blocks include end blocks provided at both ends in the tire circumferential direction, and one or more central blocks sandwiched between the end blocks, In the tire circumferential direction, the length of the central block is longer than the length of the end block, and the end block in the tire circumferential direction is formed on the groove bottom of the width direction groove. Tie bars in contact with the click and summarized in that is provided.

  According to the characteristics of the present invention, since the length of the central block is longer than the length of the end block, the central block is less likely to fall than the end block. That is, the rigidity of the central block is improved. A tie bar in contact with the end block in the tire circumferential direction is provided at the groove bottom of the width direction groove. Since the tie bar supports the end block in the tire circumferential direction, the end block can be prevented from falling down. Since the collapse of the center block and the end block can be suppressed, the block rigidity is improved as a whole large block. Therefore, even if the number of width direction sipes is increased, it is possible to further suppress a decrease in durability performance of the large block.

  In the tire radial direction, the depth from the ground contact surface of the large block to the tie bar may be shallower than the depth of the sipe in the width direction.

  The large block is divided into the three or more medium blocks and the one or more small blocks by the plurality of widthwise sipes, and the medium blocks are arranged on both sides of the one or more small blocks in the tire circumferential direction. Are adjacent to each other, and the length of the small block may be shorter than the length of the middle block in the tire circumferential direction.

  A circumferential sipe extending along the tire circumferential direction is provided on the ground contact surface of the large block, and the circumferential sipe is parallel to the tire circumferential direction and a sipe parallel portion parallel to the tire circumferential direction. And the sipe inclined part may be shallower than the sipe parallel part in the tire radial direction.

  According to the present invention, it is an object to provide a tire that can further suppress a decrease in durability performance of a large block even when the number of width direction sipes is increased.

FIG. 1 is a development view of a tread pattern of a tire according to the first embodiment. FIG. 2 is a perspective view of the large block 100 according to the first embodiment. FIG. 3 is a plan view of the large block 100 according to the first embodiment. 4 is a cross-sectional view taken along line AA in FIG. FIG. 5 is a plan view of a large block 100 according to a modification of the first embodiment. 6 is a cross-sectional view taken along line BB in FIG. FIG. 7 is a plan development view of the tread portion 1 of the tire according to the second embodiment. FIG. 8 is a plan view of the large block 101 according to the second embodiment. FIG. 9A is a partial perspective view of the large block 101 according to the second embodiment. FIG. 9B is a cross-sectional view taken along the line CC in FIG.

  An example of a tire according to the present invention will be described with reference to the drawings. Specifically, (1) the first embodiment, (2) the second embodiment, (3) comparative evaluation, and (4) other embodiments will be described.

  In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. 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. It goes without saying that the drawings include parts having different dimensional relationships and ratios.

(1) First Embodiment (1.1) Configuration of Tread Pattern A schematic configuration of a tread portion 1 of a tire according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a plan development view of the tread portion 1 of the tire according to the first embodiment. FIG. 2 is a perspective view of the large block 100 of the tire according to the first embodiment.

  The tire according to the present embodiment includes a tread portion 1 having a tire contact surface. As shown in FIG. 1, the tire according to this embodiment includes a large block 100, a tread end block 130, circumferential grooves (circumferential main grooves 200 and circumferential narrow grooves 250), a width direction groove 300, and a tread end width. A directional groove 350 is provided in the tread portion 1.

  The large block 100 is provided on the tire ground contact surface. The large block 100 is partitioned by a circumferential groove and a width direction groove 300. The plurality of large blocks 100 are arranged in the tire circumferential direction. Therefore, a block row is formed by the plurality of large blocks 100.

  The ground contact surface 100a of the large block 100 is provided with a plurality of width direction sipes 60 extending along the tread width direction. The width direction sipe 60 communicates with the circumferential groove. Specifically, the width-direction sipe 60 communicates with the circumferential main groove 200 and the circumferential narrow groove 250. The width direction sipe 60 is a so-called open sipe.

  The large block 100 is divided into three or more medium blocks 20 by a plurality of width direction sipes 60. Specifically, the large block 100 is partitioned into three medium blocks 20. The three middle blocks 20 include an end block 30 and a central block 40.

  The end blocks 30 are provided at both ends of the large block 100 in the tire circumferential direction. Therefore, the end block 30 is adjacent to the width direction groove 300 in the tire circumferential direction. The number of end blocks 30 is two. The central block 40 is sandwiched between the end blocks 30. In the present embodiment, the central block 40 is adjacent to the end block 30 in the tire circumferential direction.

  The tread end block 130 is provided on the outermost side of the tread portion 1 in the tread width direction. The tread end block 130 is partitioned by the circumferential main groove 200 and the tread end width direction groove 350. The plurality of tread end blocks 130 are arranged in the tire circumferential direction. Therefore, a block row is formed by the plurality of tread end blocks 130.

  The circumferential main groove 200 extends along the tire circumferential direction. In the present embodiment, four circumferential main grooves 200 are provided. Two circumferential main grooves 200 provided near the tire equator line CL are sandwiched between the large blocks 100 in the tread width direction. Two circumferential main grooves 200 provided near the tire equator line CL are sandwiched between the large block 100 and the tread end block 130 in the tread width direction.

  The circumferential narrow groove 250 extends along the tire circumferential direction. In the present embodiment, three circumferential narrow grooves 250 are provided. The circumferential narrow groove 250 located in the center in the tread width direction is provided on the tire equator line CL. Adjacent to the large block 100 in the tread width direction of the circumferential narrow groove 250.

  The length of the circumferential main groove 200 in the tread width direction is defined as Wa. The length of the circumferential narrow groove 250 in the tread width direction is defined as Wc. Wc is shorter than Wa. In the tread width direction, it is preferable to set Wc so that the large blocks 100 adjacent to each other across the circumferential narrow groove 250 can come into contact with each other when the tire rolls.

  In addition, at the time of prescribed internal pressure and prescribed load determined by the standards of each country such as JATMA (Japan Automobile Tire Association), TRA (The Tire and Rim Association Inc.), ETRATO (The European Tire and Rim Technical Organization), etc. What is necessary is just to contact the large blocks 100 at the time of rolling.

  The width direction groove 300 extends along the tread width direction. The width direction groove 300 defines the large block 100. Therefore, it is adjacent to the large block 100 in the tire circumferential direction of the widthwise groove 300.

  A tie bar 150 is provided at the groove bottom of the width direction groove 300. The tie bar 150 contacts the end block 30 in the tire circumferential direction. The tie bar 150 connects the side surface 105 in the tire circumferential direction of one large block 100 and the side surface 105 in the tire circumferential direction of another large block 100 adjacent to the one large block 100 in the tire circumferential direction. The tie bar 150 has an upper surface 150a facing in the tire radial direction.

  The tread end width direction groove 350 extends along the tread width direction. The tread end width direction groove 350 defines the tread end block 130. Accordingly, the tread end width direction groove 350 is adjacent to the large block 100 in the tire circumferential direction.

  The block row formed by the plurality of large blocks 100 constitutes a set of block rows with the circumferential narrow groove 250 interposed therebetween. In this embodiment, three sets of block rows are provided in the tread portion 1. That is, a center block row composed of a set of block rows is provided at the center in the tread width direction. The center block row is provided on the tire equator line CL. A second block row composed of a set of block rows is provided adjacent to the center block row with the circumferential main groove 200 interposed therebetween. The block row formed by the tread end block 130 is adjacent to the second block row with the circumferential main groove 200 interposed therebetween.

(1.2) Configuration of Large Block 100 A schematic configuration of the large block 100 will be described with reference to FIGS. FIG. 3 is a plan view of the large block 100 according to the present embodiment. That is, it is a plan view of the large block 100 in the tread surface view. 4 is a cross-sectional view taken along line AA in FIG. Specifically, FIG. 4 is a cross-sectional view of the large block 100 along the tread width direction and the tire radial direction.

  In the present embodiment, the large block 100 is constituted by the end block 30 and the central block 40. As shown in FIG. 3, let L be the length of the large block 100 in the tire circumferential direction. A length L1 of the end block 30 in the tire circumferential direction is set. The length L2 of the central block 40 in the tire circumferential direction is set. L2 is longer than L1. L2 is preferably 105% or more of L1 and 125% or less of L1. If L2 is 105% or more of L1, the block rigidity of the central block 40 is further increased, so that the block rigidity of the large block 100 can be improved. If L2 is longer than 125% of L1, the number of sipes is greatly reduced with respect to the length of the tire in the tire circumferential direction, and the ice / snow performance deteriorates.

  As shown in FIG. 4, the depth from the ground contact surface 100a of the large block 100 to the tie bar 150 in the tire radial direction is Dt. Dt is the height along the tire radial direction from the ground contact surface 100a of the large block 100 to the upper surface 150a of the tie bar 150. When the height of the upper surface 150a of the tie bar 150 changes in the tire radial direction, Dt is the length from the contact surface 100a to the position of the outermost upper surface 150a in the tire radial direction. Therefore, the height of the upper surface 150a of the tie bar 150 is higher than the groove bottom 200a of the circumferential main groove 200 in the tire radial direction.

  The depth of the width direction sipe 60 is defined as Ds. Ds is the height along the tire radial direction from the groove bottom of the width direction sipe 60 to the ground contact surface 100a.

  In this embodiment, Dt is shallower than Ds. That is, the groove bottom of the sipe 60 in the width direction is located on the inner side in the tire radial direction than the upper surface 150a of the tie bar 150. Dt is preferably 75% or more of Ds and 95% or more of Ds. If Dt is 75% or more of Ds, it is possible to suppress the concentration of strain on the groove bottom of the width-direction sipe 60 that partitions the end block 30 and the central block 40. As a result, since cracks are less likely to occur at the groove bottom of the width direction sipe 60, it is possible to further suppress a decrease in durability performance of the large block 100. In addition, the groove volume of the width direction groove 300 can be ensured. Thereby, since the snow column shear force effect can be obtained effectively, the performance on snow can be improved. If Dt is 95% or less of Ds, since the tie bar 150 supports the end block 30, the end block 30 can be prevented from falling. As a result, since the block rigidity of the large block 100 is improved, even if the number of the width direction sipes 60 is increased, it is possible to further suppress a decrease in the durability performance of the large block 100.

(1.3) Effects According to the tire according to the present embodiment, the large block 100 is partitioned into the three middle blocks 20 by the plurality of width-direction sipes 60, and the three middle blocks 20 have the tire circumference. L2 which is the length of the center block 40 is the length of the end block 30 in the tire circumferential direction, including the end block 30 provided at both ends in the direction and the center block 40 sandwiched between the end blocks 30. Longer than L1. For this reason, the central block 40 is less likely to fall than the end block 30. That is, the block rigidity of the central block 40 is improved. A tie bar 150 in contact with the end block 30 in the tire circumferential direction is provided at the groove bottom of the width direction groove 300. Since the tie bar 150 supports the end block 30 in the tire circumferential direction, the end block 30 can be prevented from falling down. Since the fall of the central block 40 and the end block 30 can be suppressed, the block rigidity of the large block 100 as a whole is improved. Therefore, even if two width direction sipes 60 are formed on the large block 100, it is possible to suppress a decrease in durability performance of the large block.

  According to the tire according to the present embodiment, the depth Dt from the ground contact surface 100a of the large block 100 to the tie bar 150 in the tire radial direction is shallower than the depth Ds of the widthwise sipe 60. Thereby, since the block rigidity of the end block 30 improves, the fall of the durable performance of a large block can further be suppressed.

(1.4) Modification A modification according to the present embodiment will be described with reference to FIGS. FIG. 5 is a plan view of a large block 100 according to a modification of the present embodiment. That is, it is a plan view of the large block 100 in the tread surface view. 6 is a cross-sectional view taken along line BB in FIG. Specifically, FIG. 5 is a cross-sectional view of the large block 100 along the tread width direction and the tire radial direction. Note that parts similar to those of the above-described embodiment are omitted as appropriate.

  As shown in FIG. 5, the large block 100 according to the modification is partitioned into three or more medium blocks 20 and one or more small blocks 50 by a plurality of width direction sipes 60. Specifically, the large block 100 is divided into three medium blocks 20 and two small blocks 50. The middle block 20 is adjacent to both sides of the small block 50 in the tire circumferential direction. Specifically, the end block 30 is adjacent to one side of the small block 50 in the tire circumferential direction. The central block 40 is adjacent to the other side of the small block 50 in the tire circumferential direction.

  The length of the small block 50 in the tire circumferential direction is L1. L3 is shorter than L1 and L2. That is, the length L1 of the small block 50 is shorter than the lengths L1 and L2 of the middle block 20. By shortening the length L1 of the small block 50, the length of the end block 30 and the central block 40 can be secured without increasing the length of the large block 100. Therefore, even if the number of the width direction sipes 60 is increased, the block rigidity of the end block 30 and the central block 40 can be secured.

  In order to divide the large block 100 into the medium block 20 and the small block 50, a plurality of width direction sipes 60 are formed in the large block 100. That is, the number of the width direction sipes 60 can be increased. Since the small block 50 is adjacent to the end block 30 and the central block 40, the small block 50 is prevented from falling. As a result, even if the number of the width direction sipes 60 is increased, a decrease in the block rigidity of the large block 100 as a whole can be suppressed, so that a decrease in the durability performance of the large block can be further suppressed.

  As shown in FIG. 6, also in this modification, the depth Dt from the ground contact surface 100a of the large block 100 to the tie bar 150 in the tire radial direction is shallower than the depth Ds of the width direction sipe 60. Thereby, since the block rigidity of the end block 30 improves, the fall of the durable performance of a large block can further be suppressed.

(2) Second Embodiment (2.1) Configuration of Tread Pattern A schematic configuration of the tread portion 1 of the tire according to the present embodiment will be described with reference to FIGS. 7 and 8. FIG. 7 is a plan development view of the tread portion 1 of the tire according to the second embodiment. Portions similar to those in the first embodiment and the modifications thereof are omitted as appropriate.

  The tire according to this embodiment includes a large block 101, a circumferential main groove 200, and a width direction groove 300 in the tread portion 1. The large block 101 is partitioned by the circumferential main groove 200 and the width direction groove 300. The plurality of large blocks 101 are arranged in the tire circumferential direction. Therefore, a block row is formed by the plurality of large blocks 101. In the present embodiment, the block row includes a center block row and a pair of second block rows. The center block row is provided on the tire equator line CL. The second block row is adjacent to the center block row across the circumferential main groove 200 in the tread width direction.

  The width direction groove 300 opens on one side surface in the tread width direction of the large block 101 and does not open on the other side surface. The positions in the tire circumferential direction of the width direction groove 300 opened on one side surface in the tread width direction of the large block 101 and the width direction groove 300 opened on the other side surface in the tread width direction of the large block 101 are They are offset from each other.

  In the first embodiment described above, the length of the tie bar 150 is equal to the length of the width direction groove 300 in the tread width direction. In the present embodiment, the length of the tie bar 150 in the tread width direction is shorter than the length of the width direction groove 300.

  Other configurations are the same as those of the above-described embodiment.

(2.2) Configuration of Large Block 101 A schematic configuration of the large block 101 will be described with reference to FIGS. FIG. 8 is a plan view of the large block 101 according to the second embodiment. That is, it is a plan view of the large block 101 in the tread surface view. FIG. 9A is a partial perspective view of the large block 101 according to the second embodiment. FIG. 9B is a cross-sectional view taken along the line CC in FIG. The CC line is a line along the circumferential sipe 80.

  A circumferential sipe 80 is provided on the ground contact surface 101a of the large block 101 according to the present embodiment. The circumferential sipe 80 extends along the tire circumferential direction. The shape of the large block 101 is a shape in which the large block 100 of the first embodiment described above is adjacent in the tread width direction. Specifically, a pair of large blocks 100 adjacent in the tread width direction are adjacent to each other with the circumferential sipe 80 interposed therebetween. Further, the pair of large blocks 100 are displaced in the tire circumferential direction. Therefore, the central block 40 of one large block 100 is adjacent to the end block 30 of the other large block 100 with the circumferential sipe 80 interposed therebetween.

  The circumferential sipe 80 includes a sipe parallel part 80a and a sipe inclined part 80b. The sipe parallel part 80a is parallel to the tire circumferential direction. The sipe inclined part 80b is inclined with respect to the tire circumferential direction.

  An auxiliary width direction sipe 65 is provided on the ground contact surface 101 a of the large block 101. The auxiliary width direction sipe 65 extends in the tread width direction. The auxiliary width direction sipe 65 is provided in the end block 30. The auxiliary width direction sipe 65 communicates only with one circumferential main groove 200.

  In the tire circumferential direction, the large blocks 101 are adjacent to each other with the communication sipe 90 and the tie bar 150 interposed therebetween. The communication sipe 90 communicates with a width direction groove 300 provided on one side in the tread width direction and a width direction groove 300 provided on the other side.

  As shown in FIGS. 9A and 9B, a protrusion 85 protruding in the tire radial direction is provided on the groove bottom of the sipe inclined portion 80b.

  As shown in FIG. 9B, the depth of the sipe parallel part 80a in the tire radial direction is defined as Dc1. Dc1 is the height along the tire radial direction from the ground contact surface 101a of the large block 101 to the groove bottom of the sipe parallel part 80a. The depth of the sipe inclined part 80b in the tire radial direction is defined as Dc2. Dc2 is the height along the tire radial direction from the ground contact surface 101a of the large block 101 to the protrusion 85. Since the protrusion 85 is provided at the groove bottom of the sipe inclined portion 80b, the depth of the sipe inclined portion 80b is shallower than the depth of the sipe parallel portion 80a in the tire radial direction.

  In the present embodiment, the depth relationship in the tire radial direction is Dc2> Dc1> Ds> Dt. That is, the depth of the sipe parallel part 80a is deeper than the depth of the sipe inclined part 80b. The depth of the sipe inclined part 80 b is deeper than the depth of the width direction sipe 60. The depth of the width direction sipe 60 is deeper than the depth from the ground contact surface 100a of the large block 100 to the tie bar 150 in the tire radial direction.

  The depth relationship in the tire radial direction is not limited to the above-described relationship, and can be changed as appropriate. For example, the depth of the sipe inclined part 80 b may be shallower than the depth of the width-direction sipe 60.

(2.3) Effects The sipe inclined portion 80b has an inclination with respect to the tire circumferential direction as compared with the sipe parallel portion 80a, and thus is easy to open in the tire circumferential direction. According to the tire according to the present embodiment, the depth of the sipe inclined portion 80b is shallower than the depth of the sipe parallel portion 80a in the tire radial direction. Thereby, since the sipe inclination part 80b becomes difficult to open rather than the sipe parallel part 80a, the block rigidity of the large block 101 can be improved.

  Since the circumferential sipe 80 has not only the sipe parallel part 80a but also the sipe inclined part 80b, the large block 101 has not only an edge component along the tire circumferential direction but also an edge component along the tread width direction. Therefore, the snow and ice performance is improved.

(3) Comparative evaluation In order to confirm the effect of the tire according to the present invention, the performance on ice and the block durability performance were evaluated. Needless to say, the present invention is not limited to the following examples.

(3.1) Examples and Comparative Examples In evaluating the performance on ice and the block durability performance, tires according to Examples and Comparative Examples shown in Table 1 were used.

  In Comparative Example 1, two width direction sipes were provided. The large block was divided into a central block and an end block by a sipe in the width direction. The width direction sipe was provided so that the length L2 of the central block was shorter than the length L1 of the end block. In Comparative Example 1, no tie bar was provided.

  In Comparative Example 2, four sipes in the width direction were provided. A large block was divided into a central block, an end block, and a small block by a sipe in the width direction. The width direction sipes were provided so that the length L2 of the central block was equal to the length L1 of the end block. In Comparative Example 2, no tie bar was provided.

  In Comparative Example 3, four sipes in the width direction were provided. A large block was divided into a central block, an end block, and a small block by a sipe in the width direction. The width direction sipe was provided so that the length L2 of the central block was larger than the length L1 of the end block. In Comparative Example 3, no tie bar was provided.

  In Comparative Example 4, four sipes in the width direction were provided. A large block was divided into a central block, an end block, and a small block by a sipe in the width direction. The width direction sipes were provided so that the length L2 of the central block was equal to the length L1 of the end block. In Comparative Example 4, a tie bar was provided. The depth Dt from the contact surface to the tie bar was set to be deeper than the depth Ds of the width direction sipe.

  In Example 1, four width direction sipes were provided. The large block was divided into a central block, an end block, and a small block by the width direction sipe. The width direction sipe was provided so that the length L2 of the central block was larger than the length L1 of the end block. In Example 1, a tie bar was provided. The depth Dt from the contact surface to the tie bar was set to be deeper than the depth Ds of the width direction sipe.

  In Example 2, four width direction sipes were provided. A large block was divided into a central block, an end block, and a small block by a sipe in the width direction. The width direction sipe was provided so that the length L2 of the central block was larger than the length L1 of the end block. In Example 2, a tie bar was provided. The depth Dt from the contact surface to the tie bar was set to be shallower than the depth Ds of the width direction sipe.

  For each tire, a tire size of 11R22.5 was used. The tread pattern was the same as the tread pattern shown in FIG. 1 except for the differences between the above-described examples and comparative examples.

(3.2) Performance on ice A vehicle equipped with each tire was suddenly accelerated from a stopped state on an icy road surface. The on-ice performance was evaluated using the time required for the vehicle to travel a predetermined distance. The numerical value of the comparative example 1 was made into the reference | standard (100), and the other numerical value was displayed with the index | exponent. The results are shown in Table 1. The larger the value, the better the performance on ice.

(3.3) Block durability performance The block durability performance was obtained by running a vehicle equipped with each tire for a predetermined distance. At the time when the wear rate of the block reached 40%, it was visually confirmed whether cracks occurred at the groove bottom of the width direction sipe. The block durability was evaluated based on the occurrence rate of cracks. The results are shown in Table 1. Based on Comparative Example 1, the evaluation was based on “◎”, “◯”, “Δ”, and “×” depending on the occurrence rate of cracks. The rate of occurrence of cracks is higher in the order of “」 ”,“ ◯ ”,“ Δ ”,“ × ”. That is, the block durability performance decreases in the order of “◎”, “◯”, “Δ”, “×”. Note that “◎” and “◯” are less cracked than Comparative Example 1. In “Δ”, cracks are generated to the same extent as in Comparative Example 1. “X” is cracked more than Comparative Example 1.

(3.4) Results

  As shown in Table 1, compared with Comparative Example 1, Examples 1 and 2 and Comparative Examples 2 to 4 have improved performance on ice. This is because the edge effect is increased by increasing the number of width direction sipes.

  In Example 1 and Example 2, compared with Comparative Examples 1-4, block durability performance is excellent. This is because the block rigidity of the central block is improved by making the length of the central block longer than the length of the end block. In addition, since the end block is supported by the tie bar, the block rigidity of the end block can be secured. As a result, the block rigidity of the large block is improved, so that the block durability performance is improved.

  In Example 2, since the depth Dt from the contact surface to the tie bar is shallower than the depth Ds of the width direction sipe, the collapse of the width direction sipe is further suppressed. Therefore, since block rigidity of the end block can be further ensured, block durability performance is improved.

  In Example 1 and Example 2, since block durability performance is improving, even if the number of width direction sipes increases, the fall of the durability performance of a large block can be suppressed.

(4) Other Embodiments Although the contents of the present invention have been disclosed through the embodiments of the present invention, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. The present invention includes various embodiments not described herein.

  For example, in the tire described above, the large block 100 is divided into the three middle blocks 20 by the width direction sipes 60, but is not limited thereto. The large block 100 may be divided into four or more medium blocks 20 by the width direction sipe 60. Therefore, for example, the large block 100 may be divided into two end blocks 30 and two central blocks 40. In this case, the small block 50 may be provided between the end block 30 and the central block 40, or the small block 50 may be provided between the central block 40 and the central block 40.

  The width direction sipe 60 is a straight line, but is not limited thereto. The width direction sipe 60 may extend along the tread width direction in a zigzag manner. Moreover, although the depth Ds of the width direction sipe 60 is the same, the width direction sipe 60 may be different.

  In the present invention, the sipe has a groove width that can be closed when the block is grounded. Specifically, the sipe has a groove width of 1.5 mm or less. However, in a tire used for a large bus or truck such as a TBR tire, the groove width of the sipe may be 1.5 mm or more.

  In addition, at the time of the specified internal pressure and specified load determined by the standards of each country such as JATMA (Japan Automobile Tire Association), TRA (The Tire and Rim Association Inc.), ETRATO (The European Tire and Rim Technical Organization), etc. It is only necessary that the sipe can be closed when grounded.

  In addition, extending along the tire circumferential direction or the tread width direction may not extend in parallel with the tire circumferential direction or the tread width direction. What is necessary is just to extend toward a tire peripheral direction or a tread width direction.

  The tire according to the present invention may be a pneumatic tire or a tire filled with rubber. Moreover, a gas-filled tire other than air containing a rare gas such as argon may be used.

  The above-described embodiments and modified examples can be used by appropriately combining the respective features as long as the effects of the present invention are not impaired.

  As described above, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the description of the present specification.

  DESCRIPTION OF SYMBOLS 1 ... Tread part, 20 ... Medium block, 30 ... End block, 40 ... Center block, 50 ... Small block, 60 ... Width direction sipe, 65 ... Auxiliary width direction sipe, 80 ... Circumferential direction sipe, 80a ... Sipe parallel part, 80b: Sipe inclined part, 85 ... Projection part, 90 ... Communication sipe, 100, 101 ... Large block, 100a, 101a ... Grounding surface, 105 ... Side surface of (large block), 130 ... Tread end block, 150 ... Tie bar, 150a ... upper surface (of tie bar), 200 ... circumferential main groove, 250 ... circumferential thin groove, 300 ... width groove, 350 ... tread end width groove

Claims (4)

A tire including a tread portion having a tire contact surface,
The tire ground contact surface is provided with a large block defined by a circumferential groove extending along the tire circumferential direction and a width groove extending along the tread width direction,
The ground contact surface of the large block is provided with a plurality of width direction sipes extending along the tread width direction,
The large block is divided into three or more medium blocks by the plurality of widthwise sipes,
The three or more middle blocks include end blocks provided at both ends in the tire circumferential direction, and one or more central blocks sandwiched between the end blocks,
In the tire circumferential direction, the length of the central block is longer than the length of the end block,
A tire having a tie bar in contact with the end block in the tire circumferential direction provided at a groove bottom of the width direction groove.   2. The tire according to claim 1, wherein in a tire radial direction, a depth from the ground contact surface of the large block to the tie bar is shallower than a depth of the width-direction sipe. The large block is partitioned into the three or more medium blocks and the one or more small blocks by the plurality of widthwise sipes.
The middle block is adjacent to both sides of the one or more small blocks in the tire circumferential direction,
2. The tire according to claim 1, wherein a length of the small block is shorter than a length of the middle block in the tire circumferential direction. A circumferential sipe extending along the tire circumferential direction is provided on the ground contact surface of the large block,
The circumferential sipe has a sipe parallel portion parallel to the tire circumferential direction, and a sipe inclined portion that is inclined with respect to the tire circumferential direction.
2. The tire according to claim 1, wherein a depth of the sipe inclined portion is shallower than a depth of the sipe parallel portion in the tire radial direction.

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