tire

Abstract

To easily provide improved performance on snow road surfaces and dry road surfaces in a compatible manner.SOLUTION: A tread portion includes a plurality of circumferential grooves 3 and 4 extending in a tire circumferential direction, and blocks 10 sectioned by a plurality of lateral grooves 5 and 6 connecting the circumferential grooves 3 and 4. In each of the blocks 10, there are disposed three or more pairs of sipes including first sipes 21 and 31 extending in a tire axial direction from one circumferential groove 3 and terminating within the block 10, and second sipes 22 and 32 extending from the other circumferential groove 4 and terminating within the block 10. The pairs of sipes include a pair of outside sipes 20 located on the outermost side in the tire circumferential direction in the block 10 and a pair of inside sipes 30 located on the inner side of the pair of outside sipes 20 in the tire circumferential direction in the block 10. An overlapping length Li of the pair of inside sipes 30 is longer than an overlapping length Lo of the pair of outside sipes 20.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a tire having a tread pattern. [Background technology]

[0002] 2. Description of the Related Art Tires have been disclosed in which a plurality of sipes extending in the tire axial direction are provided within a block (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-210105 A Summary of the Invention [Problem to be solved by the invention]

[0004] While the technology of creating multiple sipes within a block is effective in improving performance on snowy roads, it is not easy to achieve similar performance on dry roads, and further improvements are needed.

[0005] The present invention has been devised in consideration of the above-mentioned circumstances, and has as its main object to provide a tire that can easily achieve both improved performance on snowy roads and performance on dry roads. [Means for solving the problem]

[0006] The present invention is a tire having a tread portion, the tread portion having blocks divided by a plurality of circumferential grooves extending in the tire circumferential direction and a plurality of lateral grooves connecting the plurality of circumferential grooves, and the blocks are provided with three or more pairs of sipes, each pair including a first sipe extending in the tire axial direction from one circumferential groove and terminating within the block, and a second sipe extending in the tire axial direction from the other circumferential groove and terminating within the block, the sipe pairs including an outer sipe pair positioned outermost in the tire circumferential direction within the block, and an inner sipe pair positioned circumferentially more inward than the outer sipe pair within the block, and in each sipe pair, the first sipe and the second sipe have an overlapping portion that overlaps in the tire axial direction, and a length Li of the overlapping portion of the inner sipe pair is greater than a length Lo of the overlapping portion of the outer sipe pair.

[0007] In the tire according to the present invention, it is preferable that the difference Li-Lo in length of the overlapping portion is 5 to 45% of the length of the block in the tire axial direction.

[0008] In the tire according to the present invention, it is preferable that the difference Li-Lo in length of the overlapping portion is 15 to 35% of the axial length of the block.

[0009] In the tire according to the present invention, it is preferable that the distance in the tire circumferential direction between the outer sipe pair and the inner sipe pair is 1.5 to 5.0 times the distance in the tire circumferential direction between the first sipe and the second sipe.

[0010] In the tire according to the present invention, it is preferable that the block is disposed on the tire equator.

[0011] In the tire according to the present invention, it is preferable that all of the overlapping portions are disposed on the tire equator.

[0012] In the tire according to the present invention, it is preferable that a length of each block in the tire circumferential direction is greater than a length of each block in the tire axial direction.

[0013] In the tire according to the present invention, it is preferable that the one circumferential groove extends linearly and the other circumferential groove extends in a zigzag manner.

[0014] In the tire according to the present invention, it is desirable that in each sipe pair, the distance in the tire circumferential direction between the first sipe and the second sipe is 2 to 4 mm. Effect of the Invention

[0015] In the tire of the present invention, since the length Li of the overlapping portion of the inner sipe pair is greater than the length Lo of the overlapping portion of the outer sipe pair, a good edge effect is obtained in the center of the block where the inner sipe pair is arranged, and traction performance on snowy roads is improved. On the other hand, high rigidity is obtained in the tire circumferential end of the block where the outer sipe pair is arranged, and cornering performance on dry roads is obtained. This makes it possible to easily achieve both improved performance on snowy roads and performance on dry roads. [Brief description of the drawings]

[0016] [Figure 1] 1 is a development view of a tread portion showing one embodiment of a tire of the present invention. [Diagram 2] FIG. 2 is an expanded view showing a block of FIG. 1. [Diagram 3] FIG. 3 is an exploded view showing the blocks in FIG. 2. [Figure 4] FIG. 3 is a development view showing a modified example of the block in FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a development view of a tread portion 2 of a tire 1 of this embodiment. As shown in Fig. 1, in the tire 1 of this embodiment, the tread portion 2 has a block 10 divided by a plurality of circumferential grooves 3, 4 extending in the tire circumferential direction and a plurality of lateral grooves 5, 6 connecting the circumferential grooves 3 and 4.

[0018] The circumferential grooves 3, 4 may be inclined with respect to the circumferential direction of the tire, and the lateral grooves 5, 6 may be inclined with respect to the axial direction of the tire.

[0019] Three or more sipe pairs are formed in the block 10. A "sipe pair" is a pair of sipes consisting of two sipes. A "sipe" is a cut having a width of 2 mm or less (preferably 1.5 mm or less) that closes under ground contact conditions when a normal load is applied to the tire, i.e., under high ground contact pressure on the tread.

[0020] In this embodiment, one block 10 is provided with two outer sipe pairs 20 located on the outermost sides in the tire circumferential direction, and one inner sipe pair 30 located circumferentially more inward than the outer sipe pair 20 within the block.

[0021] The outer sipe pair 20 is provided at a position adjacent to the lateral groove 5 or 6. The inner sipe pair 30 is provided in the center of the block 10 so as to be sandwiched between two outer sipe pairs 20. Note that a plurality of inner sipe pairs 30 may be provided in one block 10.

[0022] The outer sipe pair 20 includes a first sipe 21 and a second sipe 22. The first sipe 21 extends in the tire axial direction from one circumferential groove 3 and terminates within the block 10. The second sipe 22 extends in the tire axial direction from the other circumferential groove 4 and terminates within the block 10. The first sipe 21 and the second sipe 22 are disposed adjacent to each other in the tire circumferential direction and constitute the outer sipe pair 20.

[0023] The first sipes 21 may be inclined with respect to the tire axial direction. The second sipes 22 extend parallel to the first sipes 21.

[0024] The outer sipe pair 20, which is composed of a first sipe 21 and a second sipe 22 that terminate within the block 10, improves on-ice performance by increasing the edge component compared to a single sipe extending from one circumferential groove 3 to the other circumferential groove 4. Also, the block 10 in which the first sipe 21 and the second sipe 22 that do not cross in the tire axial direction are formed is more likely to generate resistance against a force from the vehicle acting laterally during cornering compared to a block in which a sipe that crosses in the tire axial direction is formed, improving cornering performance on dry roads.

[0025] The inner sipe pair 30 includes a first sipe 31 and a second sipe 32. The first sipe 31 extends in the tire axial direction from one circumferential groove 3 and terminates within the block 10. The second sipe 32 extends in the tire axial direction from the other circumferential groove 4 and terminates within the block 10. The first sipe 31 and the second sipe 32 are disposed adjacent to each other in the tire circumferential direction and constitute the inner sipe pair 30.

[0026] The inner sipe pair 30, which is formed by the first sipe 31 and the second sipe 32 that terminate within the block 10, improves on-ice performance by increasing the edge component compared to a single sipe extending from one circumferential groove 3 to the other circumferential groove 4. Also, the block 10 in which the first sipe 31 and the second sipe 32 that do not cross in the tire axial direction are formed is more likely to generate resistance against a force from the vehicle acting laterally during cornering compared to a block in which a sipe that crosses in the tire axial direction is formed, improving cornering performance on dry roads.

[0027] The first sipes 31 may be inclined with respect to the tire axial direction. The first sipes 31 in this embodiment extend parallel to the first sipes 21. The second sipes 32 extend parallel to the first sipes 31.

[0028] 2 and 3 show the block 10. In the outer sipe pair 20, the first sipe 21 and the second sipe 22 have overlapping portions 23, 24 that overlap in the tire axial direction. The overlapping portions 23, 24 overlap when viewed in the tire circumferential direction, and the overlapping length is Lo.

[0029] In the inner sipe pair 30, the first sipe 31 and the second sipe 32 have overlapping portions 33, 34 that overlap in the tire axial direction. The overlapping portions 33, 34 overlap each other when viewed in the tire circumferential direction, and the overlapping length is Li.

[0030] The length Lo of the overlapping portions 23, 24 of the outer sipe pair 20 is set to be different from the length Li of the overlapping portions 33, 34 of the inner sipe pair 30. The difference between the length Li and the length Lo causes a difference in the rigidity in the tire axial direction between the inside and outside of the block 10. In this embodiment, the length Li of the overlapping portions 33, 34 of the inner sipe pair 30 is greater than the length Lo of the overlapping portions 23, 24 of the outer sipe pair 20. As a result, when a lateral force is applied from the vehicle during turning, the deformation of the outside of the block 10 is suppressed, and excellent turning performance on a dry road surface is obtained. In addition, the deformation of the inside of the block 10 is promoted, so that the block 10 deforms smoothly, and the block 10 as a whole obtains excellent grip force, and the turning performance is improved. Furthermore, the inner sipe pair 30 having the long length Li of the overlapping portions 33, 34 obtains a good edge effect, and the traction performance on a snowy road surface is improved.

[0031] That is, according to the present invention, by increasing the length Li of the overlapping parts 33, 34 at the center of the block 10, which has a relatively high rigidity, a good edge effect can be obtained without decreasing the rigidity of the entire block 10, and by decreasing the length Lo of the overlapping parts 23, 24 at the ends of the block 10, which has a relatively low rigidity, the rigidity of the block 10 can be increased without decreasing the edge performance. This makes it possible to easily achieve both improved performance on snowy roads and performance on dry roads.

[0032] The length Lo of the overlapping portions 23, 24 and the length Li of the overlapping portions 33, 34 are measured with the tire 1 in a normal state. Here, the normal state refers to a state in which the tire is mounted on a normal rim (not shown) and inflated to a normal internal pressure with no load. Hereinafter, unless otherwise specified, the dimensions of each part of the tire are values ​​measured in this normal state.

[0033] A "genuine rim" is a rim that is defined for each tire by the standard system that includes the standard on which the tire is based. For example, in the case of JATMA, it is called a "standard rim," in the case of TRA, it is called a "Design Rim," and in the case of ETRTO, it is called a "Measuring Rim."

[0034] "Normal internal pressure" is the air pressure set for each tire by each standard in the standard system including the standard on which the tire is based, such as "maximum air pressure" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and "INFLATION PRESSURE" for ETRTO. If the tire is for passenger cars, the normal internal pressure is, for example, 180 kPa.

[0035] "Normal load" refers to the load that each standard specifies for each tire in the standard system that includes the standard on which the tire is based. For example, in the case of JATMA, it is "maximum load capacity." For the TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." For the ETRTO, it is "LOAD CAPACITY." If the tire is for passenger cars, the normal load is, for example, a load equivalent to 88% of the load.

[0036] In the case of racing tires, where no applicable standards exist, the rim, air pressure and load recommended by the manufacturer shall apply.

[0037] In the block 10, the length Lo of the overlapping portions 23, 24 adjacent to the lateral groove 5 and the length Lo of the overlapping portions 23, 24 adjacent to the lateral groove 6 are equal.

[0038] In the block 10, the difference Li-Lo in length between the overlapping portions 23, 24 is preferably 5 to 45% of the length WB of the block 10 in the tire axial direction.

[0039] By making the difference Li-Lo 5% or more of the length WB, the edge effect is easily enhanced and good traction performance on snowy roads is obtained. On the other hand, by making the difference Li-Lo 45% or less of the length WB, the rigidity of the block 10 is easily ensured and good cornering performance on dry roads is obtained.

[0040] From the above viewpoint, it is more desirable for the difference Li-Lo to be 15 to 35% of the length WB of the block 10 in the tire axial direction.

[0041] 3, the tire circumferential distance D between the outer sipe pair 20 and the inner sipe pair 30 is preferably 1.5 to 5.0 times the tire circumferential distance Do between the first sipe 21 and the second sipe 22. Note that the distance D is the shortest distance between the outer sipe pair 20 and the inner sipe pair 30, and is the tire circumferential distance between the second sipe 22 on the lateral groove 5 side and the first sipe 31 in FIG. 3, or the tire circumferential distance between the first sipe 21 and the second sipe 32 on the lateral groove 6 side.

[0042] By making the distance D 1.5 times or more the distance Do, the rigidity of the block 10 is easily ensured, and good turning performance on dry roads is obtained. On the other hand, by making the distance D 5.0 ​​times or less the distance Do, the edge effect is easily enhanced, and good traction performance on snowy roads is obtained.

[0043] Moreover, the distance Do in the outer sipe pair 20 is preferably 2 to 4 mm. When the distance Do is 2 mm or more, the rigidity of the block 10 is easily ensured, and good cornering performance on dry road surfaces is obtained. On the other hand, when the distance Do is 4 mm or less, the edge effect is easily improved, and good traction performance on snowy road surfaces is obtained.

[0044] Similarly, the circumferential distance D between the outer sipe pair 20 and the inner sipe pair 30 is preferably 1.5 to 5.0 times the circumferential distance Di between the first sipe 31 and the second sipe 32. The distance Di in the inner sipe pair 30 is preferably 2 to 4 mm.

[0045] In the block 10, the distance Do in the tire circumferential direction between the first sipe 21 and the second sipe 22 adjacent to the lateral groove 5 is equal to the distance Do in the tire circumferential direction between the first sipe 21 and the second sipe 22 adjacent to the lateral groove 6.

[0046] It is desirable that the block 10 is disposed on the tire equator CL. By disposing the block 10 on the tire equator CL where the ground contact pressure tends to be high, the traction performance on snowy roads and the cornering performance on dry roads are further improved.

[0047] Furthermore, it is preferable that all overlapping portions 23, 24, 33, 34 are disposed on the tire equator CL. By disposing all overlapping portions 23, 24, 33, 34 on the tire equator CL where the ground pressure tends to be high, the traction performance on snowy roads and the cornering performance on dry roads are further improved.

[0048] It is desirable that the circumferential length LB of the block 10 is greater than the axial length WB of the block 10. The block 10 having such an elongated shape has high rigidity in the circumferential direction of the tire, which contributes to improving the steering stability on dry road surfaces.

[0049] Fig. 4 is a development view of the tread portion 2 including a block 10A which is a modified example of the block 10 in Figs. 1 to 3. For the portion of the block 10A not described below, the configuration of the block 10 described above may be adopted.

[0050] In the block 10A, one of the circumferential grooves 3A extends linearly, and the other circumferential groove 4A extends in a zigzag pattern while being inclined relative to the tire circumferential direction. The zigzag-extending circumferential groove 4A further improves traction performance on snowy road surfaces. In the block 10A, one of the circumferential grooves 3A may also extend in a zigzag pattern.

[0051] Although the tire 1 of the present invention has been described in detail above, the present invention is not limited to the above specific embodiment and may be modified in various ways. For example, in the block 10 and the block 10A, the first sipe 21, the second sipe 22, the first sipe 31, and the second sipe 32 may be formed in a wavy shape. EXAMPLES

[0052] A pneumatic tire of size 195 / 65R15 having the basic pattern of Fig. 1 was prototyped based on the specifications of Table 1, and the traction performance on snowy roads and the cornering performance on dry roads were tested. As Comparative Example 1, a tire was prepared in which three sipes extending from one circumferential groove to the other circumferential groove were formed in one block. The test method was as follows.

[0053] <Snow performance> A 2WD vehicle with an engine displacement of 1800cc and tires of each specification mounted on all wheels was brought to a test course with a snowy road surface, and the traction performance was evaluated by the test driver's senses. The results are expressed as an index with Comparative Example 1 set at 100, and the higher the value, the better the performance.

[0054] <Dry performance> The vehicle was brought to a test course with a dry road surface, and the cornering performance was evaluated by the test driver. The results are expressed as an index with Comparative Example 1 being 100, and the higher the value, the better the performance.

[0055] [Table 1]

[0056] As is clear from Table 1, it was confirmed that the tires of the examples had significantly improved traction performance on snowy road surfaces and cornering performance on dry road surfaces compared to the comparative example.

[0057] A pneumatic tire of the above size having the basic pattern shown in Fig. 1 was prototyped based on the specifications in Table 2, and the traction performance on snowy roads and the cornering performance on dry roads were tested. The test method was as follows.

[0058] <Snow performance> The vehicle was brought to a test course with a snowy road surface, and the traction performance was evaluated by a test driver. The results are expressed as an index with Example 5 being 100, and the higher the value, the better the performance.

[0059] <Dry performance> The vehicle was brought to a test course on a dry road surface, and the cornering performance was evaluated by a test driver. The results are expressed as an index with Example 5 being 100, and the higher the value, the better the performance.

[0060] [Table 2]

[0061] A pneumatic tire having the basic pattern shown in FIG. 1 and the above-mentioned size was prototyped based on the specifications in Table 3, and the traction performance on snowy roads and the cornering performance on dry roads were tested. The test method was as follows.

[0062] <Snow performance> The vehicle was brought to a test course with a snowy road surface, and the traction performance was evaluated by a test driver. The results are expressed as an index with Example 11 being 100, and the higher the value, the better the performance.

[0063] <Dry performance> The vehicle was brought to a test course on a dry road surface, and the cornering performance was evaluated by a test driver. The results are expressed as an index with Example 11 being 100, and the higher the value, the better the performance.

[0064] [Table 3]

[0065] A pneumatic tire having the basic pattern shown in Fig. 1 and the above-mentioned size was prototyped based on the specifications in Table 4, and the traction performance on snowy roads and the cornering performance on dry roads were tested. The test method was as follows.

[0066] <Snow performance> The vehicle was brought to a test course with a snowy road surface, and the traction performance was evaluated by the test driver. The results are expressed as an index with Example 16 being 100, and the higher the value, the better the performance.

[0067] <Dry performance> The vehicle was brought to a test course on a dry road surface, and the cornering performance was evaluated by a test driver. The results are expressed as an index with Example 16 being 100, and the higher the value, the better the performance.

[0068] [Table 4] [Explanation of symbols]

[0069] 1 Tire 2 Tread section 3 Circumferential groove 4 Circumferential groove 5 Yokomizo 6 Yokomizo 10 Blocks 20 Outer sipe pair 21 First sipe 22 2nd sipe 23 Overlap 24 Overlap 30 Inner sipe pair 31 First sipe 32 Second sipe 33 Overlap 34 Overlap CL Tire Equator Li Length of overlap of inner sipe pair Lo Length of overlap of outer sipe pair

Claims

1. A tire having a tread portion, The tread portion has blocks divided by a plurality of circumferential grooves extending in a tire circumferential direction and a plurality of lateral grooves connecting the plurality of circumferential grooves, The block is provided with three or more sipe pairs, each of which includes a first sipe extending in the tire axial direction from one circumferential groove and terminating within the block, and a second sipe extending in the tire axial direction from the other circumferential groove and terminating within the block; The sipe pairs include an outer sipe pair located outermost in the tire circumferential direction within the block, and an inner sipe pair located more inward in the tire circumferential direction than the outer sipe pair within the block, In each sipe pair, the first sipe and the second sipe have an overlapping portion that overlaps in the tire axial direction, A length Li of the overlapping portion of the inner sipe pair is greater than a length Lo of the overlapping portion of the outer sipe pair, The shortest distance in the tire circumferential direction between the pair of outer sipes and the pair of inner sipes adjacent to each other in the tire circumferential direction is 1.5 to 5.0 times the distance in the tire circumferential direction between the first sipe and the second sipe. tire.

2. A tire having a tread portion, The tread portion has blocks divided by a plurality of circumferential grooves extending in a tire circumferential direction and a plurality of lateral grooves connecting the plurality of circumferential grooves, The block is provided with three or more sipe pairs, each of which includes a first sipe extending in the tire axial direction from one circumferential groove and terminating within the block, and a second sipe extending in the tire axial direction from the other circumferential groove and terminating within the block; The sipe pairs include an outer sipe pair located outermost in the tire circumferential direction within the block, and an inner sipe pair located more inward in the tire circumferential direction than the outer sipe pair within the block, In each sipe pair, the first sipe and the second sipe have an overlapping portion that overlaps in the tire axial direction, A length Li of the overlapping portion of the inner sipe pair is greater than a length Lo of the overlapping portion of the outer sipe pair, The block is disposed on the tire equator. All of the overlapping portions are disposed on the tire equator. tire.

3. A tire having a tread portion, The tread portion has blocks divided by a plurality of circumferential grooves extending in a tire circumferential direction and a plurality of lateral grooves connecting the plurality of circumferential grooves, The block is provided with three or more sipe pairs, each of which includes a first sipe extending in the tire axial direction from one circumferential groove and terminating within the block, and a second sipe extending in the tire axial direction from the other circumferential groove and terminating within the block; The sipe pairs include an outer sipe pair located outermost in the tire circumferential direction within the block, and an inner sipe pair located more inward in the tire circumferential direction than the outer sipe pair within the block, In each sipe pair, the first sipe and the second sipe have an overlapping portion that overlaps in the tire axial direction, A length Li of the overlapping portion of the inner sipe pair is greater than a length Lo of the overlapping portion of the outer sipe pair, The one circumferential groove extends linearly, and the other circumferential groove extends zigzag. tire.

4. A tire as described in any one of claims 1 to 3, wherein the difference in length Li-Lo of the overlapping portion is 5 to 45% of the axial length of the block.

5. A tire as described in claim 4, wherein the difference in length Li-Lo of the overlapping portion is 15 to 35% of the axial length of the block.

6. A tire as described in any one of claims 1 to 5, wherein the circumferential length of the block is greater than the axial length of the block.

7. A tire as described in any one of claims 1 to 6, wherein in each sipe pair, the circumferential distance between the first sipe and the second sipe is 2 to 4 mm.

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