tire

Abstract

To improve on-ice performance and on-snow performance by suppressing a sipe from being clogged with snow.SOLUTION: In a tire 1, a plurality of sipes 6 arranged substantially in parallel are formed on a tread 5a of a block 5. The plurality of sipes 6 include a central sipe 6A arranged at a center side of the block 5 and outer sipes 6B arranged closer to outside than the center sipe 6A. On a cross section which is orthogonal to a longitudinal direction of the sipe 6, an angle θb of the outside sipe 6B with respect to a normal line (n) of the tread 5a is larger than an angle θa of the center sipe 6A with respect to the normal line (n), and the outer sipes 6B are inclined from the center side to the outside of the block 5, toward the outside in a tire radial direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This disclosure relates to a tire.

Background Art

[0002] Patent Document 1 below describes a studless tire in which a plurality of outer middle blocks are arranged in the tread portion. The outer middle block is provided with an outer middle main side and an outer middle sub side that extends obliquely in a direction opposite to the outer middle main side and has a smaller depth than the outer middle main side. Such a tire has excellent performance on ice.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Generally, a large force acts on the edge portion of the block when it contacts the ground and when it separates from the ground. Therefore, the side provided at this edge portion is likely to open, and when driving on an icy or snowy road, snow accumulates in this portion, and as a result, the edge of the side does not function effectively.

[0005] This disclosure has been devised in view of the above actual situation, and the main object is to provide a tire that can suppress snow accumulation in the side and improve performance on ice and snow.

Means for Solving the Problems

[0006] This disclosure relates to a tire having a plurality of blocks in the tread portion, wherein the tread surface of at least one of the plurality of blocks has a plurality of substantially parallel sipes formed thereon, the plurality of sipes including a central sipe located on the central side of the block and an outer sipe located outside the central sipe, wherein in a cross section perpendicular to the longitudinal direction of the sipes, the angle θb of the outer sipe with respect to the normal of the tread surface is greater than the angle θa of the central sipe with respect to the normal, and the outer sipes are inclined outward from the central side of the block toward the outward side in the radial direction of the tire. [Effects of the Invention]

[0007] By adopting the above configuration, the tire of this disclosure can suppress snow buildup in the sipes and improve performance on ice and snow. [Brief explanation of the drawing]

[0008] [Figure 1] This is an enlarged plan view of one embodiment of the tread portion of the present disclosure. [Figure 2] This is a cross-sectional view along line AA in Figure 1. [Figure 3] This is a plan view of the tread section. [Figure 4] (a) is a plan view of a block of another embodiment, (b) is a plan view of a block of yet another embodiment, and (c) is a plan view of a block of yet another embodiment. [Figure 5] (a) is a plan view of a block of yet another embodiment, and (b) is a cross-sectional view of (a) along line BB. [Modes for carrying out the invention]

[0009] One form of implementation of this disclosure will be described below with reference to the drawings. Figure 1 is an enlarged plan view of the tread portion 2 of the tire 1 of this disclosure. The tire 1 of this disclosure is used, for example, as a pneumatic tire for winter use. The term "winter use" means tires suitable for driving on ice and snow, including, for example, studless tires and snow tires. However, the tire 1 of this disclosure may also be used, for example, as a pneumatic tire for heavy loads or as a non-pneumatic tire that is not filled with compressed air.

[0010] As shown in Figure 1, the tire 1 of this disclosure has a plurality of blocks 5 on the tread portion 2. A plurality of sipes 6 are formed on the tread surface 5a of at least one of the plurality of blocks 5, which are arranged substantially parallel to each other. "Substantially" means that the difference in angle α of each sipe 6 with respect to the tire axis in the longitudinal direction is 15 degrees or less. In this embodiment, each sipe 6 is formed parallel to the others. Furthermore, a sipe 6 is a notch-like shape with a width of less than 1.5 mm and is clearly distinguished from a groove with a groove width of 1.5 mm or more.

[0011] The multiple sipes 6 include a central sipe 6A located on the central side of the block 5 and an outer sipe 6B located further out than the central sipe 6A. The term "central side" refers to the side closest to the centroid G of the tread surface 5a of the block 5.

[0012] Figure 2 is a cross-sectional view taken along line AA in Figure 1. Figure 2 shows a cross-section perpendicular to the longitudinal direction of the sipe 6. As shown in Figure 2, the angle θb of the outer sipe 6B with respect to the normal n of the tread surface 5a is formed to be larger than the angle θa of the central sipe 6A with respect to the normal n. Furthermore, the outer sipe 6B is inclined outward from the center of the block 5 toward the outside in the radial direction of the tire. This increases the rigidity of the root side of the end portion of the block 5 separated by the outer sipe 6B, and consequently suppresses the opening of the outer sipe 6B. Therefore, in the tire 1 of this disclosure, snow clogging of the sipe 6 (outer sipe 6B) is suppressed when driving on icy or snowy roads, so that the edges of the sipe function effectively and improve performance on icy or snowy roads.

[0013] Figure 3 is a plan view of the tread portion 2 of this embodiment. As shown in Figure 3, the tread portion 2 of this embodiment is provided with a plurality of main grooves 3 that extend continuously in the circumferential direction of the tire and a plurality of transverse grooves 4 that extend in the axial direction of the tire.

[0014] The main groove 3 includes a pair of crown main grooves 3A adjacent to the tire equator C, and a pair of shoulder main grooves 3B located outside the crown main grooves 3A in the tire axial direction. Each main groove 3 extends, for example, in a straight line along the tire circumferential direction. The main grooves 3 may extend in a zigzag or wavy pattern.

[0015] The lateral groove 4 includes a crown lateral groove 4A connecting a pair of crown main grooves 3A, a middle lateral groove 4B connecting the crown main groove 3A and the shoulder main groove 3B, and a shoulder lateral groove 4C connecting the shoulder main groove 3B and the tread edge Te. Each lateral groove 4 extends linearly, for example, along the tire axis. The lateral groove 4 may extend in a zigzag pattern or a wavy pattern. Also, each lateral groove 4 may be inclined with respect to the tire axis.

[0016] The tread edge Te is the outermost contact point in the tire's axial direction when a tire 1 in its normal state is subjected to a normal load and placed on a flat surface with a camber angle of 0 degrees. The "normal state" refers to the unloaded state in which the tire 1 is mounted on a normal rim (not shown) and filled with the normal internal pressure. Unless otherwise specified, the dimensions of each part of the tire 1 are values ​​measured in the normal state.

[0017] A "standard rim" is a rim defined for each tire within the standard system that includes the standard on which the tire is based. For example, it is a "standard rim" for JATMA, a "design rim" for TRA, and a "measuring rim" for ETRTO.

[0018] The "normal internal pressure" is the air pressure defined for each tire in the standard system including the standards on which Tire 1 is based. In the case of JATMA, it is the "maximum air pressure"; in the case of TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; and in the case of ETRTO, it is the "INFLATION PRESSURE".

[0019] The "normal load" is the load defined for each tire in the standard system including the standards on which Tire 1 is based. In the case of JATMA, it is the "maximum load capacity"; in the case of TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; and in the case of ETRTO, it is the "LOAD CAPACITY".

[0020] The block 5 of the present embodiment includes a crown block 5A, a middle block 5B, and a shoulder block 5C. The crown block 5A is adjacent to the tire equator C most closely and is divided by a pair of crown main grooves 3A and crown transverse grooves 4A. The middle block 5B is adjacent to the outside of the crown block 5A in the tire axial direction and is divided by the crown main groove 3A, the shoulder main groove 3B, and the middle transverse groove 4B. The shoulder block 5C is adjacent to the outside of the middle block 5B in the tire axial direction and is divided by the shoulder main groove 3B, the tread end Te, and the shoulder transverse groove 4C. The tread surfaces 5a of the crown block 5A, the middle block 5B, and the shoulder block 5C are formed in a rectangular shape, for example. Note that the tread surfaces 5a of the crown block 5A, the middle block 5B, and the shoulder block 5C are not limited to such a mode and various modes can be adopted.

[0021] In this embodiment, the side 6, which consists of the central side 6A and the outer side 6B of the present disclosure, is formed on each crown block 5A and each middle block 5B. Further, in the shoulder block 5C of the present embodiment, only the side 6 with an angle of 0 degrees (not shown in the figure) with respect to the normal line n of the tread surface 5a is formed. Note that the side 6, which consists of the central side 6A and the outer side 6B, may be provided only on each crown block 5A, or may be provided only on each middle block 5B. Further, the side 6, which consists of the central side 6A and the outer side 6B, may be provided on each shoulder block 5C.

[0022] As shown in FIGS. 1 and 2, the outer side 6B of the present embodiment includes a first outer side 6a adjacent to the central side 6A and a second outer side 6b arranged outside the first outer side 6a. The angle θb2 of the second outer side 6b with respect to the normal line n is formed larger than the angle θb1 of the first outer side 6a with respect to the normal line n. Therefore, by being arranged at a more end portion, snow clogging on the second outer side 6b where snow clogging is relatively likely to occur is suppressed, so that the performance on ice and snow is further improved. The difference (θb2 - θb1) between the angle θb2 of the second outer side 6b and the angle θb1 of the first outer side 6a is preferably greater than 0 degrees and preferably less than 3 degrees.

[0023] In this embodiment, the side 6 includes one central side 6A, a pair of first outer sides 6a arranged on both sides of the central side 6A, and a pair of second outer sides 6b arranged outside the first outer sides 6a. The side 6 is not limited to such a mode.

[0024] The angle θb1 of the first outer side 6a is preferably larger than the average value ((θa + θb2) / 2) of the angle θa of the central side 6A and the angle θb2 of the second outer side 6b. Thereby, the rigidity on the root side can also be increased at the first outer side 6a, so that the opening of the outer side 6B can be further suppressed.

[0025] While not particularly limited, the angle θa of the central sipe 6A is preferably 5 degrees or less, and more preferably 3 degrees or less. The most desirable angle θa of the central sipe 6A is 0 degrees. The angle θb1 of the first outer sipe 6a is preferably 3 degrees or more, more preferably 4 degrees or more, preferably 9 degrees or less, and more preferably 8 degrees or less. The angle θb2 of the second outer sipe 6b is preferably 4 degrees or more, more preferably 5 degrees or more, preferably 10 degrees or less, and more preferably 9 degrees or less.

[0026] In this embodiment, the longitudinal direction of the sipe 6 is inclined with respect to the respective longitudinal directions of the pair of lateral grooves 4 located on both sides of the block 5 on which the sipe 6 is provided, in the tire circumferential direction. Such a sipe 6 can function as an edge in a direction different from that of the block edge 5e that contacts the lateral grooves 4, thereby improving ice and snow performance. To effectively exert this effect, the angle β between the longitudinal direction of the sipe 6 and the longitudinal direction of the lateral grooves 4 is preferably 20 degrees or more and preferably 45 degrees or less.

[0027] In this embodiment, sipe 6 is an open sipe whose ends are connected to the block edge 5e. Since such sipe 6 has a large edge component, it can improve performance on ice and snow.

[0028] The spacing P between each sipe 6 should preferably be the same. "Same" means not only when the difference between the maximum and minimum spacing P is 0 mm, but also when the difference between the maximum and minimum spacing P is 20% or less of the minimum. The spacing P should preferably be 2.0 mm or more, more preferably 4.0 mm or more, more preferably 10.0 mm or less, and more preferably 8.0 mm or less.

[0029] The depth d of sipe 6 is preferably 75% or more of the block height h of block 5, more preferably 78% or more, preferably 98% or less, and more preferably 95% or less. Since the depth d of sipe 6 is 75% or more of the block height h of block 5, ice and snow performance can be maintained over a long period of time. Since the depth d of sipe 6 is 98% or less of the block height h of block 5, the opening of sipe 6 is suppressed, and the edge of the sipe can function effectively.

[0030] The depth d2 of the outer sipe 6B is the same as the depth d1 of the central sipe 6A. This reduces the rigidity step within the block 5, thereby suppressing uneven wear and a decrease in handling stability. In this specification, "the same" includes not only cases where the absolute difference |d1-d2| between the depth d2 of the outer sipe 6B and the depth d1 of the central sipe 6A is 0 mm, but also cases where it is 2 mm or less.

[0031] When the depth d1 of the central sipe 6A and the depth d2 of the outer sipe 6B are different, it is desirable that the depth d1 of the central sipe 6A be greater than the depth d2 of the outer sipe 6B. Since the central sipe 6A tends to have a smaller opening than the outer sipe 6B, even if the depth is relatively larger, snow clogging is suppressed and the edge function is improved. In this case, it is desirable that the difference between the depth d1 of the central sipe 6A and the depth d2 of the outer sipe 6B (d1-d2) be less than 2 mm.

[0032] Figure 4(a) is a plan view of block 5 in another embodiment. Components identical to those in block 5 of this embodiment are denoted by the same reference numerals, and their descriptions may be omitted. As shown in Figure 4(a), block 5 of this embodiment also has sipes 6, including a central sipe 6A and an outer sipe 6B. In this embodiment, each sipe 6 is a closed sipe, with both ends 6e terminating within the tread surface 5a of block 5. Such sipes 6 have an even smaller opening. In the case of such closed sipes, the shortest distance La between the end 6e of sipe 6 and the block edge 5e adjacent to the end 6e is preferably 0.5 mm or more, more preferably 1.0 mm or more, more preferably 2.0 mm or less, and more preferably 1.5 mm or less.

[0033] Figure 4(b) is a plan view of block 5 in yet another embodiment. Components identical to those in block 5 of this embodiment are denoted by the same reference numerals, and their descriptions may be omitted. As shown in Figure 4(b), block 5 of this embodiment also has sipes 6, including a central sipe 6A and an outer sipe 6B. In this embodiment, each sipe 6 is a semi-open sipe, with one end 6e terminating within the tread surface 5a of block 5 and the other end 6i connected to the block edge 5e. Such a sipe 6 prevents snow buildup by suppressing opening at one end 6e, while maintaining the length of the sipe 6 at the other end 6i, allowing the edge to function effectively. In this embodiment, each sipe 6 has one end 6e formed in the first tire axis direction (left side in the figure) and the other end 6i formed in the second tire axis direction (right side in the figure).

[0034] Figure 4(c) is a plan view of block 5 in yet another embodiment. Components identical to those in block 5 of this embodiment are denoted by the same reference numerals, and their descriptions may be omitted. As shown in Figure 4(c), block 5 of this embodiment also has sipes 6, including a central sipe 6A and an outer sipe 6B. In this embodiment, each sipe 6 is a semi-open sipe, with one end 6e terminating within the tread surface 5a of block 5 and the other end 6i connected to the block edge 5e. In this embodiment, sipes 6 are formed with first communicating sipes 6s and second communicating sipes 6t arranged alternately in the tire circumferential direction. For example, the first communicating sipe 6s has its first axial end 6h connected to the block edge 5e and its second axial end 6k terminating within the tread surface 5a. For example, the second communicating sipe 6t has its first axial end 6h terminating within the tread surface 5a and its second axial end 6k connected to the block edge 5e.

[0035] Figure 5(a) is a plan view of block 5 in yet another embodiment. Figure 5(b) is a cross-sectional view of block 5 in Figure 5(a) along line BB. Components identical to those in block 5 of this embodiment are denoted by the same reference numerals, and their descriptions may be omitted. As shown in Figure 5, block 5 of this embodiment also has sipes 6, including a central sipe 6A and an outer sipe 6B. Each of the sipes 6 in this embodiment is a three-dimensional sipe that extends in a zigzag pattern in the longitudinal and tire radial directions. Such sipes 6 have a pair of sipe walls that interlock in the longitudinal direction of the sipe 6, which further suppresses opening.

[0036] Although a tire according to one embodiment of the present disclosure has been described in detail above, the present disclosure is not limited to the specific embodiment described above and can be implemented in various modified forms. [Examples]

[0037] A prototype tire with the basic pattern shown in Figure 3 was manufactured based on the specifications in Table 1, and the snow-clogging performance and ice / snow performance of each test tire were tested. The test method and common specifications are as follows. Tire size: 195 / 60R15 Rim size: 15×6J Internal pressure: 230kPa

[0038] <Snow-clogging performance and performance on ice and snow> Each test tire was mounted on all wheels of the following vehicle and driven on a test course that included snow and ice surfaces. Snow-filling performance was evaluated subjectively by the test driver based on the condition of the snow packed into the sipes. Ice and snow performance was evaluated subjectively by the test driver based on steering response during cornering, rigidity, and grip. The results are shown on a scale where Comparative Example 1 is set to 100, with higher numbers indicating better performance. Vehicle: Front-wheel drive passenger car with an engine displacement of 1800cc The test results are shown in Table 1.

[0039] [Table 1]

[0040] The test results confirmed that the tires in the example had improved ice and snow performance due to reduced snow clogging of the sipes.

[0041] [Note] This disclosure includes the following aspects:

[0042] [Disclosure 1] A tire having multiple blocks on the tread, The tread surface of at least one of the aforementioned multiple blocks has a plurality of sipes that are arranged substantially parallel to each other. The plurality of sipes include a central sipe located on the central side of the block and an outer sipe located outside the central sipe. In a cross-section perpendicular to the longitudinal direction of the sipe, the angle θb of the outer sipe with respect to the normal of the tread surface is greater than the angle θa of the central sipe with respect to the normal, and the outer sipe slopes outward from the center of the block toward the outside in the radial direction of the tire. tire. [Disclosure 2] The outer sipe includes a first outer sipe adjacent to the central sipe and a second outer sipe positioned further outward than the first outer sipe. The tire according to Disclosure 1, wherein the angle θb2 of the second outer sipe with respect to the normal is greater than the angle θb1 of the first outer sipe with respect to the normal, and the second outer sipe is inclined outward from the center of the block toward the outward side in the radial direction of the tire. [Disclosure 3] The tire according to Disclosure 2, wherein the difference (θb2-θb1) between the angle θb2 of the second outer sipe and the angle θb1 of the first outer sipe is greater than 0 degrees and less than 3 degrees. [Disclosure 4] The tire according to disclosure 2 or 3, wherein the angle θb1 of the first outer sipe is greater than the average value of the angle θa of the central sipe and the angle θb2 of the second outer sipe. [Disclosure 5] A pair of transverse grooves are provided on both sides of the aforementioned block in the circumferential direction of the tire. The tire according to any one of disclosures 1 to 4, wherein the longitudinal direction of the sipe is inclined with respect to the respective longitudinal directions of the pair of transverse grooves. [Disclosure 6] The tire according to disclosure 5, wherein the angle between the longitudinal direction of the sipe and the longitudinal direction of the transverse groove is 20 to 45 degrees. [Disclosure 7] The plurality of blocks include a crown block that is closest to the tire equator, a middle block adjacent to the outer side of the crown block in the tire axial direction, and a shoulder block adjacent to the outer side of the middle block in the tire axial direction. The sipe is arranged on the crown block or the middle block, as described in any one of disclosures 1 to 6. [Disclosure 8] The depth d1 of the central sipe is greater than the depth d2 of the outer sipe. The tire according to any one of disclosures 1 to 7, wherein the difference (d1-d2) between the depth d1 of the outer sipe and the depth d2 of the central sipe is less than 2 mm. [Disclosure 9] The tire according to any one of disclosures 1 to 8, wherein the sipe is a three-dimensional sipe extending in a zigzag pattern in the longitudinal direction and the radial direction of the tire. [Disclosure 10] The tire according to any one of disclosures 1 to 9, wherein the depth of the sipe is 75% to 98% of the block height of the block. [Explanation of Symbols]

[0043] 1 tire 5 blocks 5a Tread 6 sipes 6A Central Sipe 6B Outer sipe n normal vector

Claims

1. A tire having multiple blocks on the tread, The tread surface of at least one of the aforementioned multiple blocks has a plurality of sipes that are arranged substantially parallel to each other. The plurality of sipes include a central sipe located on the central side of the block and an outer sipe located outside the central sipe. In a cross-section perpendicular to the longitudinal direction of the sipe, the angle θb of the outer sipe with respect to the normal of the tread surface is greater than the angle θa of the central sipe with respect to the normal, and the outer sipe is inclined outward from the center of the block toward the outside in the radial direction of the tire. The outer sipe includes a first outer sipe adjacent to the central sipe and a second outer sipe positioned further outward than the first outer sipe. The angle θb2 of the second outer sipe with respect to the normal is greater than the angle θb1 of the first outer sipe with respect to the normal, and the second outer sipe is inclined outward from the center of the block toward the outer side in the radial direction of the tire. The difference (θb2 - θb1) between the angle θb2 of the second outer sipe and the angle θb1 of the first outer sipe is greater than 0 degrees and less than 3 degrees. tire.

2. A tire having a plurality of blocks on the tread portion, The tread surface of at least one of the aforementioned multiple blocks has a plurality of sipes that are arranged substantially parallel to each other. The plurality of sipes include a central sipe located on the central side of the block and an outer sipe located outside the central sipe. In a cross-section perpendicular to the longitudinal direction of the sipe, the angle θb of the outer sipe with respect to the normal of the tread surface is greater than the angle θa of the central sipe with respect to the normal, and the outer sipe is inclined outward from the center of the block toward the outside in the radial direction of the tire. The depth d1 of the central sipe is greater than the depth d2 of the outer sipe. The difference between the depth d1 of the central sipe and the depth d2 of the outer sipe (d1-d2) is less than 2 mm. tire.

3. The outer sipe includes a first outer sipe adjacent to the central sipe and a second outer sipe positioned further outward than the first outer sipe. The tire according to claim 2, wherein the angle θb2 of the second outer sipe with respect to the normal is greater than the angle θb1 of the first outer sipe with respect to the normal, and the second outer sipe is inclined outward from the center of the block toward the outward side in the radial direction of the tire.

4. The tire according to claim 3, wherein the difference (θb2 - θb1) between the angle θb2 of the second outer sipe and the angle θb1 of the first outer sipe is greater than 0 degrees and less than 3 degrees.

5. The tire according to claim 3 or 4, wherein the angle θb1 of the first outer sipe is greater than the average value of the angle θa of the central sipe and the angle θb2 of the second outer sipe.

6. A pair of transverse grooves are provided on both sides of the block in the circumferential direction of the tire, The tire according to any one of claims 1 to 5, wherein the longitudinal direction of the sipe is inclined with respect to the respective longitudinal directions of the pair of transverse grooves.

7. The tire according to claim 6, wherein the angle between the longitudinal direction of the sipe and the longitudinal direction of the transverse groove is 20 to 45 degrees.

8. The plurality of blocks include a crown block that is closest to the tire equator, a middle block adjacent to the outer side of the crown block in the tire axial direction, and a shoulder block adjacent to the outer side of the middle block in the tire axial direction. The tire according to any one of claims 1 to 7, wherein the sipes are arranged on the crown block or the middle block.

9. The tire according to any one of claims 1 to 8, wherein the sipe is a three-dimensional sipe extending in a zigzag pattern in the longitudinal direction and the radial direction of the tire.

10. The tire according to any one of claims 1 to 9, wherein the depth of the sipe is 75% to 98% of the block height of the block.

Images