Tire

Abstract

Tires (10, 10A, 10B, 10C, 10D, 10E) have tread block groups (31, 32, 33) that are divided by a pair of circumferential grooves (41, 42, 43, 44) extending along the tire circumference (TC). Each tread block group includes multiple tread blocks (100, 200, 300) that are divided by multiple width-direction grooves (61, 62, 63) extending along the tire width direction (WD). Each tread block in the tread block group (31, 32, 33) is divided into multiple smaller tread blocks (101, 201, 301, 101A, 201A, 301A, 101B, 201B, 301B, 101C, 201C, 301C, 101D, 301E) by circumferential sipes (120, 220, 320) and multiple width-direction sipes (130, 230, 330). Within each tread block, the circumferential sipes extend in a serrated pattern, and at least the outermost width-direction sipes in the tire circumferential (TC) direction of the multiple width-direction sipes extend parallel to each other.

Description

Technical Field

[0001] This invention relates to a tire that uses a tread pattern with densely arranged tread blocks having a relatively small contact area. Background Technology

[0002] Previously, it was known that a method was used in winter tires (hereinafter referred to as tires) suitable for driving on icy and snowy roads, using a tread pattern with densely arranged tread blocks with a relatively small contact area (Patent Document 1).

[0003] Tread patterns with such densely arranged small tread blocks provide better contact with icy and snowy surfaces compared to tread blocks of normal size, thus improving driving performance on icy and snowy surfaces (the following is about ice performance).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2017-193202 Summary of the Invention

[0007] However, the aforementioned tires still have room for improvement in the following aspects. Specifically, further improvements are needed in ice performance, particularly braking performance on icy and snowy roads when driving straight.

[0008] Therefore, the object of the present invention is to provide a tire that can further improve braking performance on icy and snowy roads when driving straight, when using a tread pattern with densely arranged tread blocks of relatively small contact area.

[0009] One technical solution of the present invention is a tire having a tread block group, which is divided by a pair of circumferential grooves extending along the tire circumference. The tread block group includes a plurality of tread blocks, each divided by a plurality of width-direction grooves extending along the tire width direction. Each of the plurality of tread blocks is further divided into a plurality of smaller tread blocks by circumferential sipes extending along the tire circumference and a plurality of width-direction sipes extending along the tire width direction. Within each of the plurality of tread blocks, the circumferential sipes extend in a serrated pattern, and at least the outermost width-direction sipes in the tire circumferential direction extend parallel to each other.

[0010] In a tire with the above structure, the tread blocks in the tread block group are divided into smaller tread blocks by serrated circumferential sipes and multiple width-direction sipes. In this structure, during braking, each smaller tread block supports itself not only with adjacent smaller tread blocks in the tire circumferential direction but also with adjacent smaller tread blocks in the tire width direction, thus improving the circumferential bending stiffness of each tread block. This improved bending stiffness, in turn, enhances the tire's contact patch during braking.

[0011] Therefore, by using the above-mentioned tires, and with the use of a tread pattern that has densely arranged tread blocks with a relatively small contact area, the braking performance on icy and snowy roads when driving straight can be further improved. Attached Figure Description

[0012] Figure 1 This is a partial planar unfolded view of the tread of the pneumatic tire 10.

[0013] Figure 2 This is a magnified top view of part of the tread 20.

[0014] Figure 3 It is a partial cross-sectional view of the tread block 100 containing circumferential sipes 120 (width direction sipes 130) along the width direction of the sipes and the radial direction TR of the tire.

[0015] Figure 4 This is a partial planar development view of the tread of the pneumatic tire 10A of Modified Example 1.

[0016] Figure 5 This is a partial planar development view of the tread of the pneumatic tire 10B in Modified Example 2.

[0017] Figure 6 This is a partial planar development view of the tread of the pneumatic tire 10C of Modified Example 3.

[0018] Figure 7 This is a partial planar development view of the tread of the pneumatic tire 10D in Modified Example 4.

[0019] Figure 8 This is a partial planar development view of the tread of the pneumatic tire 10E in Modification Example 5. Detailed Implementation

[0020] The embodiments are described below based on the accompanying drawings. Furthermore, descriptions of the same or similar functions and structures are omitted where appropriate.

[0021] (1) Overall general structure of the tire

[0022] Figure 1 This is a partial planar development view of the tread of an inflatable tire 10 according to one embodiment.

[0023] The pneumatic tire 10 of this embodiment is a so-called winter tire, also known as a studless anti-skid tire, capable of driving on icy and snowy roads, specifically ice and snow-covered roads. Alternatively, the pneumatic tire 10 can also be an all-season tire capable of driving on both non-icy and snowy roads (wet and dry roads) and icy and snowy roads. Or, the pneumatic tire 10 can also be a typical summer tire instead of a winter tire, an all-season tire.

[0024] Furthermore, there are no particular restrictions on the types of vehicles on which the pneumatic tires 10 can be installed, but they can primarily be passenger cars (and may also include SUVs and minivans).

[0025] The pneumatic tire 10 uses a tread pattern with densely arranged tread blocks that have a relatively small contact area with the ground.

[0026] Specifically, such as Figure 1 As shown, the pneumatic tire 10 has tread block rows 31, 32, 33, 34, and 35 extending along the tire circumferential direction TC. Specifically, the pneumatic tire 10 includes tread block rows 31, 32, and 33, which are respectively groups of tread blocks, divided by a pair of adjacent circumferential grooves 41, 42, 43, and 44, and tread block rows 34 and 35, which are divided by the circumferential grooves 43, 44 and the tread end.

[0027] The tread 20 is the part that contacts the road surface. The tread 20 has a tread pattern that corresponds to the usage environment of the pneumatic tire 10 and the type of vehicle on which it is installed.

[0028] In the tread 20, a tread block row 31 is provided at a position including the tire equator CL, and tread block rows 32 and 33 are provided on the outer side of the tread block row 31 in the tire width direction.

[0029] In addition, tread block row 34 is provided on the outer side of tread block row 32 in the tire width direction, and tread block row 35 is provided on the outer side of tread block row 33 in the tire width direction.

[0030] Pattern block 31 is divided by a pair of circumferential grooves extending along the tire circumference TC, specifically circumferential groove 41 and circumferential groove 42.

[0031] Tread block row 32 is divided by circumferential grooves 42 and 43. Tread block row 33 is divided by circumferential grooves 41 and 44. In addition, since tread block rows 34 and 35 are located in the shoulder area of ​​the tread 20, circumferential grooves are not formed on the outer side in the tire width direction.

[0032] (2) The shape of the patterned blocks

[0033] Figure 2This is a partially enlarged top view of the tread 20. As described above, the tread 20 has multiple rows of tread blocks extending along the tire circumferential direction TC, each row containing multiple tread blocks that contact the road surface.

[0034] Specifically, each tread block row comprises multiple tread blocks divided by a plurality of width-direction grooves extending along the tire width direction (WD). Specifically, tread block row 31 comprises tread block 100. Tread block row 32 comprises tread block 200. Tread block row 33 comprises tread block 300. Tread block row 34 comprises tread block 400. Tread block row 35 comprises tread block 500.

[0035] Pattern block 100 is divided by width direction groove 61. Pattern block 200 is divided by width direction groove 62. Pattern block 300 is divided by width direction groove 63. Pattern block 400 is divided by width direction groove 64. Pattern block 500 is divided by width direction groove 65.

[0036] The width of the tread blocks 100 included in the tread block row 31 in the tire circumferential TC may not all be the same. In this embodiment, the tread blocks 100 divided by the mutually parallel width direction grooves 61 are alternately arranged with tread blocks 1001 that are wider in the tire circumferential direction and tread blocks 1003 that are narrower in the tire circumferential direction.

[0037] Patterned block arrays 32 and 33 have roughly the same shape as patterned block array 31.

[0038] Specifically, in this embodiment, in the tread block array 32, the tread blocks 200 divided by the width direction groove 62 are alternately arranged with tread blocks that are wider and tread blocks that are narrower in the circumferential direction in the tire circumferential direction. Similarly, in the tread block array 33, the tread blocks 300 divided by the width direction groove 63 are alternately arranged with tread blocks that are wider and tread blocks that are narrower in the circumferential direction in the tire circumferential direction.

[0039] The tread block 100 is divided into multiple small tread blocks 101 by the circumferential sipes 120 extending along the tire circumferential direction TC and the width sipes 130 extending along the tire width direction WD.

[0040] Specifically, the pattern block 100 is divided into 9 small pattern blocks 101 by 2 circumferential groove patterns 120 and 2 width-direction groove patterns 130.

[0041] In this embodiment, each end of the width-direction groove pattern 130 is connected to one of the circumferential grooves. Specifically, the ends of the width-direction groove pattern 130 are connected to the circumferential grooves 41 and 42.

[0042] Furthermore, the circumferential groove pattern 120 extends in a serrated shape. The two ends of the circumferential groove pattern 120 are connected to the width-direction groove 61 adjacent to the pattern block 100.

[0043] Furthermore, in this embodiment, the width-direction groove 61 and the width-direction sipe pattern 130 are inclined relative to the tire width direction WD. The width-direction groove 61 and the width-direction sipe pattern 130 are parallel when viewed from above the tire tread. That is, the inclination angle of the width-direction groove 61 relative to the tire width direction WD is the same as the inclination angle of the width-direction sipe pattern 130 relative to the tire width direction WD.

[0044] In this embodiment, the width-direction groove pattern 130 and the circumferential groove pattern 120 intersect at the bend of the serrated circumferential groove pattern 120.

[0045] The shape of each small tread block 101, divided by the circumferential sipes 120 and the width-direction sipes 130, when viewed from above, can be a polygon formed by at least four sides. In this embodiment, the small tread blocks 101 are quadrilateral. Specifically, the tire circumferential TC of the small tread blocks 101 is divided by multiple parallel width-direction sipes 130 or width-direction grooves 61 formed parallel to the width-direction sipes 130. The tire width-direction WD of the small tread blocks 101 is divided by parallel circumferential sipes 120 or circumferential grooves 41, 42. Therefore, the small tread blocks 101 adjacent to the circumferential grooves 41, 42 become trapezoidal columns when viewed from above, and the small tread blocks 101 divided at both ends of the tire width-direction WD by the circumferential sipes 120 become parallelogram columns.

[0046] At least patterned blocks 200 and 300 have approximately the same shape as patterned block 100.

[0047] Specifically, the pattern block 200 is divided into 9 smaller pattern blocks 201 by 2 circumferential groove patterns 220 and 2 width-direction groove patterns 230.

[0048] The ends of the width-direction groove pattern 230 are connected to the circumferential grooves 42 and 43. Furthermore, the circumferential groove pattern 220 extends in a serrated shape. The circumferential groove pattern 220 is not directly connected to the circumferential grooves 42 and 43 adjacent to the same pattern block 200, but rather its two ends are connected to the width-direction groove 62 adjacent to the same pattern block 200.

[0049] Furthermore, the width-direction groove 62 and the width-direction sipe pattern 230 are inclined relative to the tire width direction (WD). The width-direction groove 62 and the width-direction sipe pattern 230 are parallel when viewed from above the tire tread.

[0050] Furthermore, in this embodiment, the width-direction groove pattern 230 and the circumferential groove pattern 220 intersect at the bends of the serrated circumferential groove pattern 220.

[0051] Pattern block 300 is divided into 9 small pattern blocks 301 by 2 circumferential groove patterns 320 and 2 width-direction groove patterns 330.

[0052] The ends of the width-direction groove pattern 330 are connected to the circumferential grooves 41 and 44. Furthermore, the circumferential groove pattern 320 extends in a serrated shape. The circumferential groove pattern 320 is not directly connected to the circumferential grooves 41 and 44 adjacent to the same pattern block 200, but rather its two ends are connected to the width-direction groove 63 adjacent to the same pattern block 300.

[0053] Furthermore, the width-direction groove 63 and the width-direction sipe pattern 330 are inclined in the opposite direction to the width-direction groove 61 and the width-direction sipe pattern 130 relative to the tire width direction (WD). Also, the width-direction groove 63 and the width-direction sipe pattern 330 are parallel when viewed from above the tire tread.

[0054] Furthermore, in this embodiment, the width-direction groove pattern 330 and the circumferential groove pattern 320 intersect at the bends of the serrated circumferential groove pattern 320.

[0055] like Figure 1 As shown, in the pneumatic tire 10, a tread block array 31 comprising parallelogram-shaped tread blocks 100 having quadrilateral columnar tread blocks 101, a tread block array 32 comprising parallelogram-shaped tread blocks 200 having quadrilateral columnar tread blocks 201, and a tread block array 33 comprising parallelogram-shaped tread blocks 300 having quadrilateral columnar tread blocks 301 are provided only in the central portion CT. The central portion CT is divided by a pair of circumferential grooves 43, 44 located at the outermost position in the tire width direction and arranged across the tire equator CL.

[0056] Pattern block 400 is divided into 6 smaller pattern blocks 401 by one circumferential groove pattern 420 and two width-direction groove patterns 430.

[0057] The inner end of the width-direction sipe 430 is connected to the circumferential groove 43. The end of the circumferential sipe 420 is connected to the width-direction groove 64 formed adjacent to the tread block 400.

[0058] The circumferential sipes 420 formed by the tread blocks 400, including the tread end, extend in a straight line along the tire circumferential direction TC. In addition, the width-direction sipes 430 disposed in the tread blocks 400 bend at the intersection with the circumferential sipes 420.

[0059] Furthermore, the width-direction groove 64 and the width-direction sipe pattern 430 are inclined relative to the tire width direction (WD). Alternatively, as... Figure 1 As shown, a portion of the circumferential groove 43 side of the width direction groove 64 and the width direction grooving pattern 430 is further inclined compared to the other portions.

[0060] Pattern block 500 is also divided into 6 small pattern blocks 501 by one circumferential groove pattern 520 and two width-direction groove patterns 530.

[0061] The inner end of the width-direction sipe 530 is connected to the circumferential groove 44. The end of the circumferential sipe 520 is connected to the width-direction groove 65 formed adjacent to the tread block 500.

[0062] The circumferential sipes 520 formed by the tread blocks 500, including the tread end, extend in a straight line along the tire circumferential direction TC. In addition, the width-direction sipes 530 disposed in the tread blocks 400 bend at the intersection with the circumferential sipes 520.

[0063] Furthermore, the width-direction groove 65 and the width-direction sipe pattern 530 are inclined relative to the tire width direction (WD). Alternatively, as... Figure 2 As shown, a portion of the circumferential groove 43 side of the width direction groove 65 and the width direction grooving pattern 530 is further inclined compared to the other portions.

[0064] In addition, such as Figure 1 As shown, patterned blocks 400 and 500 have point-symmetric shapes.

[0065] (3) Cross-sectional shape of circumferential groove pattern and width direction groove pattern

[0066] Figure 3 It is a partial cross-sectional view of a tread block 100 containing circumferential sipes 120 or width-direction sipes 130 along the width direction of the sipes and the radial direction TR of the tire.

[0067] Furthermore, at least the circumferential groove patterns 220 and 320 formed on the pattern blocks 200 and 300 have the same cross-sectional shape as the circumferential groove pattern 120 formed on the pattern block 100. In addition, the width-direction groove patterns 230 and 330 also have the same cross-sectional shape as the width-direction groove pattern 130.

[0068] like Figure 3As shown, in this embodiment, the circumferential sipe 120 has a constant groove width GW1 from the road surface side to the bottom portion. The width-direction sipe 130 also has a constant groove width GW1 from the road surface side to the bottom portion. Specifically, the cross-sectional shapes of the circumferential sipe 120 and the width-direction sipe 130 in the cross-section along the sipe width direction and the tire radial direction TR are formed such that the sipe wall surfaces have groove wall surfaces that extend linearly along the tire radial direction TR and are substantially parallel to each other.

[0069] In addition, the groove pattern is a narrow groove that closes within the ground plane of the patterned block. The opening width of the groove pattern when not grounded is not particularly limited, but it is preferably 0.1mm to 1.5mm, more preferably 0.4mm to 0.7mm.

[0070] In this embodiment, the depth D1 of the circumferential groove pattern 120 and the width groove pattern 130 is set to about 5.0 mm, and the groove width GW1 is set to about 0.4 mm.

[0071] (4) Dimensions and bending stiffness of the patterned blocks

[0072] As mentioned above, patterned blocks 200 and 300 have approximately the same shape as patterned block 100, therefore, they are referred to here as... Figure 2 The dimensions and bending stiffness of the patterned block are illustrated using the patterned block 100 shown in the figure as an example.

[0073] like Figure 2 As shown, the dimension W1 of the tread block 100 along the tire width direction WD is longer than the dimension L1 of the tread block 100 along the tire circumference direction TC. That is, the tread block 100 is longer in the lateral direction.

[0074] Furthermore, the ratio W2 / W1 of the tire width of the small tread block 101 to the tire width of the tread block 100 is 0.25 or more and 0.50 or less. More preferably, W2 / W1 is 0.30 or more and 0.45 or less. The ratio L2 / L1 of the tire circumferential length of the small tread block 101 to the tire circumferential length of the tread block 100 is 0.1 or more and 0.5 or less, preferably 0.15 or more and 0.45 or less. L2 / L1 is preferably less than W2 / W1.

[0075] In addition, such as Figure 2 As shown, the width W1, width W2, length L1, and length L2 are based on the tire width direction WD and the tire circumferential direction TC. Furthermore, the width W2 of the small tread block 101 can also be based on the distance from the end of the small tread block 101 in the tire width direction to the center of the serrated circumferential sipes 120 in the tire width direction, or the distance between the centers of two adjacent circumferential sipes 120.

[0076] The height of the patterned block 100, that is, the depth of the circumferential grooves 41 and 42 and the width grooves 61 that divide the patterned block 100, can also be not constant, ranging from 6mm to 12mm.

[0077] The moment of inertia of the section of the small patterned block 101 unit, with respect to the height direction, is 150 (mm). 4 ) and above and 2200 (mm) 4 The preferred ranges for the width W2 and length L2 of the individual small patterned block 101 are: width W2 = 9mm to 15mm and length L2 = 6mm to 12mm.

[0078] Furthermore, the moment of inertia of the cross section is preferably 300 (mm). 4 )~1500 (mm) 4 ), more preferably 500 (mm) 4 )~1000 (mm) 4 The small tread blocks 101 adjacent to the circumferential grooves 41 and 42 of the tread block 100 are trapezoidal columnar when viewed from above, and their moment of inertia can be calculated using (Equation 1).

[0079] (Equation 1) Moment of inertia of section I = {(a 2 +4ab+b 2 )×h 3} / (36a+36b)

[0080] Here, as Figure 2 As shown, the length of the upper base of the trapezoidal tread block 101 when viewed from above is set as a, the length of the lower base is set as b, and the height in the direction perpendicular to the width direction sipe 130 is set as h.

[0081] Furthermore, the small pattern blocks 101 at both ends, which are divided by the circumferential grooving pattern 120, are parallelogram-shaped columns when viewed from above. The moment of inertia of the cross section is calculated using (Equation 2).

[0082] (Equation 2) Moment of inertia of section I = (W² × L²) 3 ) / 12

[0083] The preferred relationship between the length L2 and width W2 of the individual small patterned block 101 is 1.0 ≤ W2 / L2 ≤ 1.5. By setting W2 / L2 to 1.0 or higher, grounding performance is improved, and ice performance is enhanced. Furthermore, by setting W2 / L2 to 1.5 or lower, water generated on the surface of the road surface R can be removed, further improving ice performance.

[0084] (5) Functions and effects

[0085] According to the above-described implementation, the following effects can be achieved. Specifically, the pattern block 100 (and other pattern blocks as well) is divided into multiple small pattern blocks 101 by the circumferential groove pattern 120 and the width-direction groove pattern 130. The circumferential groove pattern 120 and the width-direction groove pattern 130 have a constant groove width GW1 from the ground surface side to the bottom portion.

[0086] In other words, since the circumferential sipes 120 and the width-direction sipes 130, each with a constant groove width GW1 up to the bottom portion, extend along the tire circumferential direction TC and the tire width direction WD respectively, the edge pressure at the ends of the tread block 100 in the tire circumferential direction TC and the tire width direction WD can be ensured. Furthermore, since the edge portion of the tread block 100 is divided (divided) by the circumferential sipes 120, the water-repellent performance of the contact surface of the tread block 100 can also be ensured.

[0087] Furthermore, as described above, sufficient edge pressure is ensured in the small tread blocks 101 at the ends of the tire circumferential TC constituting the tread blocks 100, thus significantly improving grip on icy and snowy roads and effectively enhancing braking performance. Additionally, other small tread blocks 101 located behind the small tread blocks 101 at the ends of the tire circumferential TC constituting the tread blocks 100 are able to maintain close contact with the road surface.

[0088] In this way, instead of multiple small patterned blocks 101 each having the objectives of "grounding", "edge effect" and "water removal (drainage)" respectively, each small patterned block 101 shares the functions of "grounding", "edge effect" and "water removal (drainage)" as described above.

[0089] Thus, by using pneumatic tires 10, and with a tread pattern that is densely packed with tread blocks that have a relatively small contact area, performance on ice can be improved.

[0090] Furthermore, in this embodiment, the size ratio W2 / W1 between the small patterned block 101 and the patterned block 100 is 0.25 or more and 0.50 or less, and the moment of inertia of the section of the individual patterned block 100 with respect to the height direction is 150 (mm). 4 ) and above and 2200 (mm) 4 )the following.

[0091] Therefore, the performance of "grounding", "edge effect" and "water removal (drainage)" can be achieved at a high level. By having W2 / W1 of 0.25 or higher, the size of the small patterned block 101 is not too small, thus ensuring sufficient grounding and edge effect. Furthermore, by having W2 / W1 of 0.50 or lower, the size of the small patterned block 101 is not too large, thus ensuring sufficient grounding.

[0092] By using a pneumatic tire 10 and setting the bending stiffness of W2 / W1 and the individual tread blocks 100 within the aforementioned range, it is possible to improve braking performance, handling stability, and other dynamic performance, not only on icy and snowy roads but also on dry roads. In other words, by using a pneumatic tire 10 and employing a tread pattern with densely packed tread blocks having a relatively small contact patch, higher dynamic performance can be achieved.

[0093] In this embodiment, the small tread blocks 101 (and other tread blocks and small tread blocks are substantially the same) are prism-shaped quadrilaterals when viewed from above. Therefore, adjacent small tread blocks 101 can efficiently support each other using the circumferential sipes 120 and the width-direction sipes 130. Especially for braking performance on icy and snowy roads during straight-line driving, this structure ensures that each small tread block 101 supports not only the small tread blocks 101 adjacent in the tire circumferential direction TC but also the small tread blocks 101 adjacent in the tire width direction WD during braking. Therefore, the flexural stiffness of each tread block 100 in the tire circumferential direction TC is improved. By thus improving the flexural stiffness of the tire circumferential direction TC, the tire's contact patch during braking is further improved.

[0094] In this embodiment, the end of the width-direction groove pattern 130 is connected to the circumferential groove 41 and circumferential groove 42, and the end of the circumferential groove pattern 120 is connected to the width-direction groove 61 formed adjacent to the pattern block 100. Therefore, sufficient water removal performance can be achieved while ensuring the rigidity of the pattern block 100 (pattern block rigidity).

[0095] In this embodiment, the width W2 of the tread block 100 is greater than the length L2 of the tread block 100, and the tread block 100 is longer in the lateral direction. As a result, the edge effect (also known as the edge component) of the end of the tread block 100 in the tire circumferential TC can be improved, and in particular, the braking performance, which is very important on icy and snowy roads, can be effectively improved.

[0096] In this embodiment, the width-direction groove 61 and the width-direction sipe pattern 130 are inclined relative to the tire width direction WD, and the width-direction groove 61 and the width-direction sipe pattern 130 are parallel. As a result, uneven wear of the tread block 100 and noise (tread vibration noise) generated when the tread block 100 contacts the road surface can be suppressed.

[0097] (6) Other implementation methods

[0098] The above describes the implementation method, but is not limited to the description of this implementation method. Various modifications and improvements can be made, which is self-evident to those skilled in the art.

[0099] For example, the tread pattern of the pneumatic tire 10 described above can also be changed as follows. Figure 4 This is a partial planar development view of the tread 20A of the pneumatic tire 10A in Modified Example 1.

[0100] like Figure 4 As shown, the pneumatic tire 10A has tread block rows 31A, 32A, and 33A, which are respectively grouped as tread block groups. Tread block row 31A includes tread block 100A, tread block row 32A includes tread block 200A, and tread block row 33A includes tread block 300A.

[0101] The following explanation uses patterned block 100A as an example. Figure 4 As shown, the pattern block 100A is divided into 9 small pattern blocks 101A by 2 circumferential groove patterns 120A and 2 width-direction groove patterns 130A.

[0102] Compared to the tread block 100 of the embodiment, in Modification 1, the two ends of the tread block 100A in the tire width direction WD are formed into a serrated shape parallel to the circumferential sipes 120A when viewed from above. In Modification 1, the small tread blocks 101A adjacent to the circumferential grooves 41A and 42A are also parallelogram-shaped columns when viewed from above. In Modification 1, since the ends of the tread block 100A in the width direction are serrated, the tread 20A has circumferential grooves 41A and 42A extending in a serrated shape with the width direction end faces of the tread block 100A as groove walls, which is also different from the tread 20 of the embodiment where the circumferential grooves extend in a straight line.

[0103] like Figure 4 As shown, in the pneumatic tire 10A, the tread blocks 31A, 32A, and 33A are only provided in the central CTA, which is divided by a pair of circumferential grooves 43A and 44A located on the outermost side in the tire width direction and arranged across the tire equator CL.

[0104] Figure 5 This is a partial planar development view of the tread 20B of tire 10B in modified example 2.

[0105] like Figure 5 As shown, the pneumatic tire 10B has tread block rows 31B, 32B, and 33B, which are respectively grouped as tread block groups. Tread block row 31B includes tread block 100B, tread block row 32B includes tread block 200B, and tread block row 33B includes tread block 300B.

[0106] The following explanation uses patterned block 100B as an example. Figure 5 As shown, the pattern block 100B is divided into 7 small pattern blocks 101B by 2 circumferential groove patterns 120B and 4 width-direction groove patterns 130B.

[0107] Compared with the tread block 100 of the embodiment, in the modified example 2, the small tread block 101B includes hexagonal prism-shaped (hexagonal when viewed from above) small tread blocks, which is different.

[0108] Specifically, such as Figure 5 As shown, the pattern block 100B is divided by a circumferential groove pattern 120B that extends in a serrated shape and whose two ends communicate with adjacent width-direction grooves 61B, and multiple width-direction groove patterns 130B that terminate at least one end within the pattern block 100B. Furthermore, the ends of the width-direction groove patterns 130B that terminate within the pattern block 100B communicate with the circumferential groove pattern 120B at the bend point of the circumferential groove pattern 120B.

[0109] In addition, in the modified example 2, the two ends of the width-direction sipe 130B are connected to the nearest bending position of the two circumferential sipes 120B in the tire width direction, or to the nearest bending position of the circumferential grooves 41B, 42B and the circumferential sipe 120B in the tire width direction from the circumferential grooves 41B, 42B, thereby making each small tread block 101B into a hexagonal prism shape.

[0110] Compared with the tread block 100 of the embodiment, in the modified example 2, since the small tread block 101B located at the end in the tire width direction WD is hexagonal prism, it has circumferential grooves 41B and 42B extending in a serrated shape in the tread 20B, which is also different from the tread 20 of the embodiment.

[0111] like Figure 5 As shown, in the pneumatic tire 10B, the tread blocks 31B, 32B, and 33B are only provided in the central portion CTB, which is divided by a pair of circumferential grooves 43B and 44B located on the outermost side in the tire width direction and arranged across the tire equator CL.

[0112] In the pneumatic tire 10B of Modified Example 2, each tread block supports the two adjacent small tread blocks 101B in the tire width direction WD when turning. Therefore, it can not only improve the bending stiffness of each tread block 100B in the tire circumferential direction TC, but also improve the bending stiffness in the tire width direction WD.

[0113] Figure 6 This is a partial planar development view of the tread 20C of tire 10C in modified Example 3.

[0114] like Figure 6 As shown, the pneumatic tire 10C has tread block rows 31C, 32C, and 33C, which are respectively grouped as tread block groups. Tread block row 31C includes tread block 100C, tread block row 32C includes tread block 200C, and tread block row 33C includes tread block 300C.

[0115] The following explanation uses patterned block 100C as an example. Figure 6 As shown, the pattern block 100C is divided into 8 small pattern blocks 101C by 2 circumferential groove patterns 120C and 5 width-direction groove patterns 130C.

[0116] Compared with the tread block 100 of the embodiment, in the modified example 3, the small tread block 101C includes small tread blocks with a shape in which the width of the tread block at both ends of the tire circumferential TC when viewed from above is wider than the width of the tread block at the center.

[0117] Specifically, such as Figure 6 As shown, each tread block 100C is formed into a parallelogram shape when viewed from above. Furthermore, each tread block 100C is divided by a circumferential sipe 120C extending in a serrated shape and connected at both ends to adjacent width-direction grooves 61C, and multiple width-direction sipes 130C terminating at least one end within the tread block 100C. The ends of the width-direction sipes 130C terminating within the smaller tread blocks 101C are connected to the circumferential sipes 120C at the bend point of the circumferential sipes 120C.

[0118] In Modification Example 3, the two ends of the width-direction sipe 130C, which terminates within the tread block 100C, are connected to the furthest bends of the two circumferential sipes 120C in the tire width direction. Furthermore, only one end of the width-direction sipe 130C, which terminates within the tread block 100C, is connected to the circumferential grooves 41C and 42C, while the other end is connected to the furthest bend of the circumferential sipe 120C in the tire width direction from the circumferential grooves 41C and 42C.

[0119] Therefore, compared to the case in Modified Example 2 where the tread block 100B includes hexagonal prism-shaped small tread blocks 101B, the tread block 100C of the tread block row 31C formed in Modified Example 3 includes small tread blocks in the shape where, when viewed from above, the width of the tread blocks at both ends of the tire circumferential TC is wider than the width of the tread blocks at the center.

[0120] like Figure 6 As shown, in the pneumatic tire 10C, the tread blocks 31C, 32C, and 33C are only provided in the central part CTC, which is divided by a pair of circumferential grooves 43C and 44C located on the outermost side in the tire width direction and arranged across the tire equator CL.

[0121] The pneumatic tire 10C of Modified Example 3 has a larger moment of inertia of the section of the small tread block 101C with respect to the height direction, which can suppress the collapse of the small tread block 101C and improve the friction on ice.

[0122] Figure 7 This is a partial planar development view of the tread 20D of tire 10D in modified Example 4.

[0123] like Figure 7 As shown, the pneumatic tire 10D has a tread block group 31D in its central portion CTD, which is divided by a pair of circumferential grooves 41D and 42D arranged across the tire equator CL. The tread block group 31D includes a plurality of tread blocks 100D, which are divided by a plurality of width-direction grooves 61D that are inclined relative to the tire width direction WD and communicate with the circumferential grooves 41D but not with the circumferential grooves 42D, and a plurality of width-direction grooves 62D that are inclined relative to the tire width direction WD in the opposite direction to the width-direction grooves 61D and communicate with the circumferential grooves 42D but not with the circumferential grooves 41D.

[0124] like Figure 7 As shown, the pattern block 100D, which is not adjacent to the circumferential grooves 41D and 42D, is divided into 9 small pattern blocks 101D by 4 circumferential groove patterns 120D and 4 width-direction groove patterns 130D.

[0125] The pattern block 100D adjacent to the circumferential grooves 41D and 42D is divided into 12 small pattern blocks 101D by 4 circumferential groove patterns 120D and 7 width-direction groove patterns 130D.

[0126] Specifically, such as Figure 7 As shown, the pattern block 100D is divided by a circumferential groove pattern 120D that extends in a serrated shape and is connected at both ends to the adjacent width-direction grooves 61D and 62D, and by multiple width-direction groove patterns 130D that terminate at at least one end within the pattern block 100D, in either the case where it is not adjacent to the circumferential grooves 41D and 42D or in the case where it is adjacent to the circumferential grooves 61D and 62D. Moreover, the two ends of the width-direction groove pattern 130D that terminate within the small pattern block 101D are connected to the circumferential groove pattern 120D at the bending position of the circumferential groove pattern 120D.

[0127] In the modified example 4, the two ends of the width-direction sipe 130D are connected to the nearest bending position of the two circumferential sipe 120D in the tire width direction, so that each small tread block 101D becomes a hexagonal prism.

[0128] Comparing the tread 20 of the embodiment and the tread 20D of the modification example 4, in the tread 20 of the embodiment, multiple tread block groups (tread block rows 31, 32, 33) are arranged in the central CTD, but in the tread 20D of the modification example 4, a single tread block group 31D is arranged in the central CTD, which is different.

[0129] Furthermore, the pattern block group 31D is divided into multiple pattern blocks 100D by multiple intersecting width direction grooves 61D and 62D, which is different from the pattern block columns 31, 32, and 33 in the embodiment where the pattern block column 31 is divided into multiple pattern blocks 100 by the mutually parallel width direction grooves 61.

[0130] The pneumatic tire 10D of Modified Example 4 supports each tread block with two adjacent small tread blocks 101D in the tire width direction WD when turning. Therefore, it can not only improve the bending stiffness of each tread block 100D in the tire circumferential direction TC, but also improve the bending stiffness in the tire width direction WD.

[0131] like Figure 7 As shown, in the pneumatic tire 10D, the tread block group 31D is only provided in the central part CTD, which is divided by a pair of circumferential grooves 41D and 42D located on the outermost position in the tire width direction and arranged across the tire equator CL.

[0132] Furthermore, the pneumatic tire 10D of Modified Example 4 has multiple intersecting width direction grooves 61D and 62D in the tread block group 31D located in the center CTD, which ensures high drainage performance when driving straight.

[0133] Figure 8 This is a partial planar development view of the tread 20E of the pneumatic tire 10E in Modified Example 5.

[0134] like Figure 8 As shown, the pneumatic tire 10E has tread block rows 31 and 32, which are respectively grouped as tread block sets. Tread block row 31 includes tread block 100, and tread block row 32 includes tread block 200.

[0135] like Figure 8 As shown in Modification Example 5, the pneumatic tire 10E may also have tread blocks 300E in the tread block row 33E, which are divided into multiple small tread blocks 301E by circumferential sipes 320E extending parallel to the tire circumferential direction TC and multiple width direction sipes 330E including first width direction sipes and second width direction sipes extending in different directions, instead of the tread blocks 300 included in the tread block row 33 of the pneumatic tire 10 in the embodiment.

[0136] The entire contents of Japanese Special Appeal No. 2021-101627 (application date: June 18, 2021) are incorporated herein by reference.

[0137] The present disclosure has been described in detail above, but it will be clear to those skilled in the art that the present disclosure is not limited to the embodiments described herein. The present disclosure can be implemented in modified and altered forms without departing from the spirit and scope of the present disclosure as defined by the claims. Therefore, the description in this disclosure is for illustrative purposes and is not intended to be restrictive.

Claims

1. A tire comprising a tread block group, the tread block group being divided by a pair of circumferential grooves extending along the circumference of the tire, wherein, The tread block group comprises multiple tread blocks, each defined by multiple width-direction grooves extending along the tire width direction. Each of the multiple tread blocks is divided into multiple smaller tread blocks by multiple circumferential sipes extending along the tire circumference and multiple width sipes extending along the tire width. Within each of the plurality of tread blocks, the circumferential sipes extend in a serrated pattern, and at least the outermost width-direction sipes in the tire circumferential direction of the plurality of width-direction sipes extend parallel to each other. The plurality of small tread blocks include a first small tread block whose width at both ends of the tire circumferential direction is wider than the width of the tread block at the center when viewed from above. Within each of the plurality of tread blocks, the two ends of the width-direction sipes terminating within the tread block are respectively connected to the furthest bends of two of the plurality of circumferential sipes in the tire width direction. Furthermore, only one end of the width-direction sipe terminated within the tread block is connected to the plurality of circumferential grooves, and this one end is connected to the furthest bend of one of the two circumferential sipes in the tire width direction from that circumferential groove.

2. The tire according to claim 1, wherein, The tire has the tread block group only in the center, which is divided by a pair of circumferential grooves located on the outermost side in the tire width direction and arranged across the tire equator.

3. The tire according to claim 1 or 2, wherein, The circumferential groove pattern has a constant groove width from the contact surface side to the bottom portion. The multiple groove patterns in the width direction each have a constant groove width from the ground surface to the bottom portion.

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