tire

Abstract

The present invention provides a tire that improves handling stability on dry roads and performance on ice and snow. The tire has a tread portion. The tread portion includes a plurality of circumferential grooves extending continuously along the circumference of the tire, and a land portion defined by the circumferential grooves. A plurality of inclined sipes are provided on the tread surface of the land portion along the circumference of the tire. The inclined sipes include a first inclined sipe and a second inclined sipe. The first inclined sipe includes: a first deep bottom portion arranged on a first circumferential edge side; and a first shallow bottom portion arranged on a second circumferential edge side and having a depth less than the first deep bottom portion. The second inclined sipe includes: a second deep bottom portion arranged on a second circumferential edge side; and a second shallow bottom portion arranged on the first circumferential edge side and having a depth less than the second deep bottom portion. The second deep bottom portion is arranged at a position overlapping an area obtained by extending the first deep bottom portion parallel to the tire axial direction.

Description

Technical Field

[0001] The present invention relates to tires. Background Art

[0002] Patent Document 1 below proposes a pneumatic radial tire that improves on-snow performance by defining tread pattern elements. Specifically, the tire connects longitudinal and transverse sipes in a substantially L-shape, thereby anticipating improved on-snow cornering and braking performance.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2006-160055

[0004] In recent years, there has been a demand for tires that can cope with various road conditions, and in particular, for tires that have excellent handling stability on dry roads and performance on ice and snow. Summary of the Invention

[0005] The present invention has been made in view of the above-mentioned actual situation, and its main object is to provide a tire having improved handling stability on dry roads and performance on ice and snow.

[0006] The present invention is a tire having a tread portion, the tread portion including a plurality of circumferential grooves extending continuously in the tire circumferential direction, and at least one first land portion defined by the circumferential grooves, the first land portion having a first circumferential edge, a second circumferential edge, and a tread surface therebetween, the tread surface having a plurality of inclined sipes provided circumferentially in the tire, the inclined sipes being inclined in a first direction relative to the tire axial direction, the inclined sipes including a first inclined sipe and a second inclined sipe adjacent to each other in the tire circumferential direction, the first inclined sipe including a first deep bottom portion disposed on the first circumferential edge side, and a first shallow bottom portion disposed on the second circumferential edge side and having a depth less than that of the first deep bottom portion, the second inclined sipe including a second deep bottom portion disposed on the second circumferential edge side, and a second shallow bottom portion disposed on the first circumferential edge side and having a depth less than that of the second deep bottom portion, the second deep bottom portion being disposed at a position overlapping a projection area obtained by extending the first deep bottom portion parallel to the tire axial direction.

[0007] In the tire of the present invention, it is preferable that the first land portion be provided on the tire equator.

[0008] In the tire of the present invention, it is preferable that the angle of the inclined sipe relative to the tire axial direction is 15 to 55 degrees.

[0009] In the tire of the present invention, it is preferred that the oblique sipes extend from the first circumferential edge to the second circumferential edge.

[0010] In the tire of the present invention, a first short groove and a second short groove are provided in the first land portion. The first short groove extends from the first circumferential edge and is interrupted in the first land portion, and the second short groove extends from the second circumferential edge and is interrupted in the first land portion.

[0011] In the tire of the present invention, it is preferable that the first short groove and the second short groove are inclined in a second direction opposite to the first direction.

[0012] In the tire of the present invention, it is preferred that a first short groove, a second short groove, and a connecting sipe are provided in the above-mentioned first land portion, the above-mentioned first short groove extends from the above-mentioned first circumferential edge and is interrupted in the above-mentioned first land portion, the above-mentioned second short groove extends from the above-mentioned second circumferential edge and is interrupted in the above-mentioned first land portion, and the above-mentioned connecting sipe extends from the above-mentioned first short groove to the above-mentioned second short groove.

[0013] In the tire of the present invention, it is preferable that the maximum depth of the connecting sipes is smaller than the maximum depth of the first deep bottom portion and the maximum depth of the second deep bottom portion.

[0014] In the tire of the present invention, the tread portion preferably includes a second land portion adjacent to the first land portion, the second land portion having a first circumferential edge, a second circumferential edge, and a tread therebetween, and a plurality of transverse sipes are provided on the tread of the second land portion, the transverse sipes extending from the first circumferential edge to the second circumferential edge.

[0015] In the tire of the present invention, the above-mentioned transverse sipe pattern preferably includes: a first part, which is connected to the above-mentioned first circumferential edge and is inclined toward a second direction opposite to the above-mentioned first direction; a second part, which is connected to the above-mentioned second circumferential edge and is inclined toward the above-mentioned second direction; and a third part, which is inclined toward the above-mentioned first direction between the above-mentioned first part and the above-mentioned second part.

[0016] The tire of the present invention, by adopting the above-described structure, can improve steering stability on dry roads and performance on ice and snow. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a development view of the tread portion of a tire according to one embodiment of the present invention.

[0018] Figure 2 yes Figure 1 An enlarged view of the first land part.

[0019] Figure 3 yes Figure 2 AA line section view.

[0020] Figure 4 yes Figure 2 BB line cross-sectional view.

[0021] Figure 5 yes Figure 2 An enlarged top view of the first inclined sipe and the second inclined sipe.

[0022] Figure 6 yes Figure 2 CC line cross-sectional view.

[0023] Figure 7 yes Figure 1 An enlarged view of the second land part.

[0024] Figure 8 yes Figure 7 Magnified view of the cross-sipe pattern.

[0025] Figure 9 yes Figure 7 DD line cross-sectional view.

[0026] Figure 10 yes Figure 1 An enlarged view of the third land part.

[0027] Description of Reference Numerals

[0028] 2…tread portion; 3…circumferential groove; 6…land portion; 6a…first circumferential edge; 6b…second circumferential edge; 6s…tread surface; 10…inclined sipes; 11…first inclined sipes; 12…second inclined sipes; 16…first deep bottom portion; 17…first shallow bottom portion; 21…second deep bottom portion; 22…second shallow bottom portion. DETAILED DESCRIPTION

[0029] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

[0030] Figure 1 This is a developed view of a tread portion 2 of a tire 1 according to one embodiment of the present invention. The tire 1 of this embodiment is suitable, for example, as an all-season pneumatic tire for passenger cars. However, the present invention is not limited to this embodiment and may also be applied to winter tires, for example.

[0031] like Figure 1 As shown, the tread portion 2 includes a plurality of circumferential grooves 3 extending continuously in the tire circumferential direction between two tread ends Te, and a plurality of land portions partitioned by the circumferential grooves 3 .

[0032] The two tread ends Te correspond to the outermost ground contact positions in the tire axial direction when a normal load is applied to the tire 1 in a normal state and the tire contacts a flat surface at a camber angle of 0°.

[0033] "Normal condition" refers to the condition of a pneumatic tire with specified specifications, assembled on a specified rim, inflated to a specified internal pressure, and unloaded. For tires without specified specifications or non-pneumatic tires, the "normal condition" refers to the standard usage condition appropriate for the tire's intended use and unloaded. Unless otherwise specified, the dimensions of various tire components in this specification are values measured under this "normal condition."

[0034] "Regular rims" are rims with specifications specified for each tire within the standard system that includes the tire's specifications. For example, they are "standard rims" for JATMA, "design rims" for TRA, and "measuring rims" for ETRTO.

[0035] "Regulated internal pressure" refers to the air pressure specified for each tire within the specification system that includes the tire's specifications. For JATMA, it is the "maximum air pressure." For TRA, it is the maximum value stated in the table "TIRE LOAD LIMITS ATVARIOUS COLD INFLATION PRESSURES." For ETRTO, it is the "INFLATION PRESSURE."

[0036] For pneumatic tires with various specifications, the "normal load" refers to the load specified for each tire within the standard system that includes the tire's specifications. For JATMA, this is the "maximum load capacity," for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, it is "LOAD CAPACITY." Furthermore, for tires without various specifications or non-pneumatic tires, the "normal load" refers to the load acting on a single tire in its standard mounting state. This "standard mounting state" refers to a tire mounted on a standard vehicle appropriate for the tire's intended use, with the vehicle stationary on a flat road surface in a drivable state.

[0037] The circumferential grooves 3 include, for example, two crown circumferential grooves 4 and two shoulder circumferential grooves 5 .

[0038] Two crown circumferential grooves 4 are provided across the tire equator C. Two shoulder circumferential grooves 5 are provided across the two crown circumferential grooves 4. The axial distance L1 from the groove centerline of the crown circumferential groove 4 to the tire equator C is, for example, 5% to 15% of the tread width TW. The axial distance L2 from the groove centerline of the shoulder circumferential groove 5 to the tire equator C is, for example, 20% to 35% of the tread width TW. The tread width TW is the axial distance from one tread end Te to the other tread end Te.

[0039] Each circumferential groove 3 extends in a straight line parallel to the tire circumferential direction, for example. Each circumferential groove 3 may also extend in a zigzag or wavy shape along the tire circumferential direction.

[0040] The groove width W1 of the circumferential groove 3 is preferably 3.0% to 6.0% of the tread width TW, for example. The depth of the circumferential groove 3 (not shown) is preferably 5.0 to 15.0 mm, for example. However, the circumferential groove 3 is not limited to this embodiment.

[0041] The land portion of this embodiment includes a first land portion 6, a second land portion 7, and a third land portion 8. The first land portion 6 is defined between two crown circumferential grooves 4 and is located on the tire equator C. The second land portion 7 is defined between the crown circumferential grooves 4 and the shoulder circumferential grooves 5. In this embodiment, two second land portions 7 are located between the first land portion 6. The third land portion 8 includes the tread end Te and is defined axially outward of the shoulder circumferential grooves 5. In this embodiment, two third land portions 8 are located between one first land portion 6 and two second land portions 7.

[0042] Figure 2 FIG shows an enlarged view of the first land portion 6. Figure 2 As shown, the first land portion 6 includes a first circumferential edge 6a, a second circumferential edge 6b, and a tread surface 6s therebetween.

[0043] A plurality of inclined sipes 10 are provided along the tire circumferential direction on the tread surface 6s of the first land portion 6. The inclined sipes 10 are inclined in a first direction (toward the upper right in the various figures of this specification) relative to the tire axial direction. The inclined sipes 10 include a first inclined sipe 11 and a second inclined sipe 12 adjacent to each other in the tire circumferential direction.

[0044] In this specification, a "sipe" refers to a narrow cutout element, where the width between two facing sipe walls is 1.5 mm or less. The sipe width is preferably 0.3 to 1.2 mm, more preferably 0.5 to 1.0 mm. The sipes of this embodiment have a width within the aforementioned range throughout their entire depth. Sipes may also be connected to chamfered openings or drum bottoms with widths greater than the aforementioned range.

[0045] exist Figure 3 In FIG. 1 , a cross-sectional view of the first inclined sipe 11 is shown. Figure 2 AA line section view. Figure 4 In FIG. 1 , a cross-sectional view of the second inclined sipe 12 is shown. Figure 2 BB line cross-sectional view. Figure 3 As shown, the first inclined sipe 11 includes: a first deep bottom 16 arranged on the first circumferential edge 6a side; and a first shallow bottom 17 arranged on the second circumferential edge 6b side and having a depth smaller than that of the first deep bottom 16. Figure 4 As shown, the second inclined sipe 12 includes a second deep bottom 21 arranged on the second circumferential edge 6 b side and a second shallow bottom 22 arranged on the first circumferential edge 6 a side and having a smaller depth than the second deep bottom 21 .

[0046] Figure 5 FIG shows an enlarged top view of the first inclined sipe 11 and the second inclined sipe 12. Figure 5 In order to facilitate understanding of the features of the invention, the first deep bottom 16 and the second deep bottom 21 are colored. Figure 5 As shown, the second deep bottom portion 21 is positioned so as to overlap with the projection area of the first deep bottom portion 16, which is extended parallel to the tire axial direction. By adopting the above-described structure, the tire 1 of the present invention can improve handling stability on dry roads and performance on ice and snow. The reason for this is presumably the following mechanism.

[0047] The first and second inclined sipes 11, 12 exert frictional forces in the circumferential and axial directions on icy and snowy roads, improving braking and cornering performance on ice and snow. Furthermore, the arrangement of the first deep base 16 and first shallow base 17 of the first inclined sipe 11, and the arrangement of the second deep base 21 and second shallow base 22 of the second inclined sipe 12, help evenly balance rigidity in the circumferential direction of the tire, improving forward stability. The presence of high-rigidity and low-rigidity portions facilitates slip angle formation, enabling smooth cornering. This effect contributes to improved handling stability on dry roads (hereinafter sometimes referred to as "handling stability").

[0048] Furthermore, in the present invention, the second deep bottom portion 21 is positioned so as to overlap with the projection of the first deep bottom portion 16 extending parallel to the tire axial direction. Therefore, when the first oblique sipes 11 and the second oblique sipes 12 contact the ground, the first deep bottom portion 16 and the second deep bottom portion 21 open together, providing a greater frictional force from their edges. This is believed to further improve performance on snow and ice.

[0049] The following further describes the detailed structure of this embodiment. Furthermore, each of the structures described below represents a specific form of this embodiment. Therefore, the present invention can achieve the aforementioned effects even without the structures described below. Furthermore, any of the structures described below can be applied individually to a tire of the present invention having the aforementioned features, and performance improvements corresponding to each structure can be expected. Furthermore, when several of the structures described below are applied in combination, performance improvements corresponding to the combination of each structure can be expected.

[0050] like Figure 2 As shown, the inclined sipe 10 of this embodiment extends from the first circumferential edge 6a to the second circumferential edge 6b, traversing the first land portion 6. However, the present invention is not limited to this, and the inclined sipe 10 may be interrupted within the first land portion 6.

[0051] The oblique sipes 10 extend, for example, in a straight line. Thus, when the facing sipe walls of the oblique sipes 10 contact each other, the first land portion 6 easily undergoes shear deformation in the longitudinal direction of the oblique sipes 10. This deformation prevents snow from clogging the crown circumferential grooves 4 and the interior of the oblique sipes 10.

[0052] The angle of the inclined sipe 10 relative to the tire axial direction is, for example, 15 to 55 degrees, preferably 30 to 50 degrees. In the case where the angle of the inclined sipe 10 is small, the intervals between the inclined sipes 10 arranged along the tire circumference are preferably small, so that the above-mentioned second deep bottom 21 is arranged at a position overlapping with the projection area of the first deep bottom 16. In addition, it is preferred that the first inclined sipe 11 and the second inclined sipe 12 are inclined at angles close to each other. The angle difference between the first inclined sipe 11 and the second inclined sipe 12 is preferably less than 10 degrees, more preferably less than 5 degrees. As a further preferred embodiment, in the present embodiment, the first inclined sipe 11 and the second inclined sipe 12 are arranged parallel to each other. As a result, the braking performance and cornering performance on ice and snow are improved in a balanced manner.

[0053] The maximum distance L3 in the tire circumferential direction between adjacent first and second inclined sipes 11, 12 is, for example, 50% or less, preferably 20% to 45%, and more preferably 30% to 40% of the axial width W2 of the first land portion 6. This arrangement of first and second inclined sipes 11, 12 improves both steering stability and performance on snow and ice in a balanced manner.

[0054] like Figure 3As shown, the first inclined sipe 11 includes a first deepening portion 18, the depth of which varies along the longitudinal direction of the sipe between the first deep bottom portion 16 and the first shallow bottom portion 17. Thus, the first deep bottom portion 16 and the first shallow bottom portion 17 each extend at a constant depth.

[0055] The depth d1 of the first deep bottom portion 16 is, for example, 60% to 80% of the depth of the crown circumferential groove 4. The axial length L4 of the first deep bottom portion 16 is the axial width W2 of the first land portion 6 (e.g., Figure 2 35% to 55% of the total cost of production.

[0056] The depth d2 of the first shallow bottom portion 17 is, for example, at least 50% of the depth d1 of the first deep bottom portion 16, preferably 55% to 75%, and more preferably 60% to 70%. Such a first shallow bottom portion 17 can improve performance on snow and ice while maintaining the rigidity of the first land portion 6.

[0057] Axial length L5 of first shallow bottom portion 17 is preferably at least 80%, more preferably at least 90%, and preferably at most 120%, more preferably at most 110%, of axial length L4 of first deep bottom portion 16. Such first deep bottom portion 16 and first shallow bottom portion 17 can improve handling stability and performance on snow and ice while suppressing uneven wear of first land portion 6.

[0058] like Figure 4 As shown, the second inclined sipe 12 includes a second deepening portion 23. The depth of the second deepening portion 23 varies along the length of the sipe, between the second deep base 21 and the second shallow base 22. Consequently, the second deep base 21 and the second shallow base 22 each extend at a constant depth. The structures of the first deep base 16, first shallow base 17, and first deepening portion 18 described above can be applied to the second deep base 21, the second shallow base 22, and the second deepening portion 23, respectively, and therefore their description is omitted here.

[0059] like Figure 5 As shown, the length L12 of the overlapping region between the first deep bottom portion 16 and the second deep bottom portion 21 in the tire circumferential direction is preferably 30% or more, more preferably 50% or more, and in the present embodiment, 60% to 80% of the length L11 of the first deep bottom portion 16 in the tire circumferential direction. This ensures the aforementioned effects.

[0060] like Figure 2As shown, in this embodiment, a plurality of sipe pairs 14 of first oblique sipes 11 and second oblique sipes 12 are arranged in the tire circumferential direction, and third oblique sipes 13 are provided between the sipe pairs 14. The structure of the third oblique sipes 13, as viewed from above the tread, can be applied to the configuration of the first oblique sipes 11 or the second oblique sipes 12 described above.

[0061] Figure 6 In the Figure 2 The CC line cross-sectional view. Figure 6 As shown, the third inclined sipe 13 of this embodiment includes a central shallow bottom 26 provided at the center in the longitudinal direction thereof and an outer deep bottom 27 provided between the central shallow bottom 26 and the crown circumferential groove 4 .

[0062] The central shallow bottom portion 26 is, for example, located in the center of a region dividing the third oblique sipe 13 into three equal parts along its longitudinal direction, including the axial center of the third oblique sipe 13. The axial length L7 of the central shallow bottom portion 26 is, for example, 30% to 45% of the axial width W2 of the first land portion 6. This central shallow bottom portion 26 prevents excessive opening of the third oblique sipe 13, thereby reducing uneven wear of the first land portion 6 and improving steering stability. The length L7 of the central shallow bottom portion 26 is measured, for example, at its height center.

[0063] The depth d3 of the central shallow bottom portion 26 is, for example, 40% to 55% of the depth of the crown circumferential groove 4 .

[0064] In this embodiment, the central shallow bottom portion 26, the first shallow bottom portion 17, and the second shallow bottom portion 22 are formed to have the same depth. This achieves the above-mentioned effects and further suppresses uneven wear of the first land portion 6.

[0065] When the tread is viewed from above, the central shallow bottom portion 26 is preferably arranged at a position overlapping with a projection area obtained by extending the first shallow bottom portion 17 or the second shallow bottom portion 22 parallel to the tire axial direction.

[0066] The depth d4 of the outer deep bottom portion 27 is, for example, 60% to 80% of the depth of the crown circumferential groove 4. In this embodiment, the outer deep bottom portion 27, the first deep bottom portion 16, and the second deep bottom portion 21 are configured to have the same depth.

[0067] like Figure 2As shown, in the first land portion 6 of this embodiment, a plurality of inclined sipe groups 15 are provided along the tire circumferential direction. Each inclined sipe group 15 is composed of five inclined sipes 10. Each inclined sipe group 15 includes two sipe pairs 14, each consisting of a first inclined sipe 11 and a second inclined sipe 12, and a single third inclined sipe 13 disposed between the sipe pairs 14. Furthermore, a first short groove 31 and a second short groove 32 are provided between two adjacent inclined sipe groups 15 along the tire circumferential direction. The first short groove 31 extends from the first circumferential edge 6a and is interrupted within the first land portion 6. The second short groove 32 extends from the second circumferential edge and is interrupted within the first land portion 6. Furthermore, a connecting sipe 30 is provided in the first land portion 6, extending from the first short groove 31 to the second short groove 32.

[0068] The first short grooves 31 and the second short grooves 32 are inclined in a second direction (the lower right direction in the figures of this manual) opposite to the first direction. The angle of the first short grooves 31 and the second short grooves 32 relative to the tire axial direction is, for example, 15 to 55 degrees, preferably 30 to 50 degrees. This allows for greater friction on ice and snow in a direction different from that of the inclined sipes 10, thereby improving cornering and braking performance on ice and snow.

[0069] For example, the first short grooves 31 and the second short grooves 32 are interrupted without intersecting the axial center of the first land portion 6. The axial length L8 of the first short grooves 31 and the second short grooves 32 is, for example, 15% to 35% of the axial width W2 of the first land portion 6, and preferably 20% to 30%. These first short grooves 31 and second short grooves 32 improve both steering stability and performance on snow and ice in a balanced manner.

[0070] The depth of the first short groove 31 and the second short groove 32 is, for example, 60% to 80% of the depth of the crown circumferential groove 4. The first short groove 31 and the second short groove 32 of the present embodiment have the same depth as the first deep bottom portion 16.

[0071] The connecting sipes 30 are inclined, for example, in a first direction. The angle of the connecting sipes 30 relative to the tire axial direction is, for example, 15 to 55 degrees, preferably 30 to 50 degrees. In this embodiment, the connecting sipes 30 have an angular difference of 5 degrees or less from the inclined sipes 10. In a more preferred embodiment, the connecting sipes 30 extend parallel to the inclined sipes 10. These connecting sipes 30, together with the inclined sipes 10, enhance braking and cornering performance on ice and snow.

[0072] The maximum depth of the connecting sipe 30 is smaller than the maximum depth of the first deep bottom portion 16 and the maximum depth of the second deep bottom portion 21. The depth of the connecting sipe 30 is, for example, 40% to 55% of the depth of the crown circumferential groove 4. In the present embodiment, it is the same as the depth of the first shallow bottom portion 17 and the second shallow bottom portion 22. This suppresses uneven wear of the first land portion 6.

[0073] Figure 7 FIG shows an enlarged view of the second land portion 7. Figure 7 As shown, the second land portion 7 includes a first circumferential edge 7a, a second circumferential edge 7b, and a tread surface 7s therebetween.

[0074] The tread surface 7s of the second land portion 7 is provided with a first interrupted groove 33, a second interrupted groove 34, a first connecting sipe 37, a second connecting sipe 38, and a transverse sipe 40. The first interrupted groove 33 extends from the first circumferential edge 7a and has an interrupted end 33a within the tread surface 7s. The second interrupted groove 34 extends from the second circumferential edge 7b and has an interrupted end 34a within the tread surface 7s. The first connecting sipe 37 extends from the interrupted end 33a of the first interrupted groove 33 to the second circumferential edge 7b. The second connecting sipe 38 extends from the interrupted end 34a of the second interrupted groove 34 to the first circumferential edge 7a. The transverse sipe 40 extends from the first circumferential edge 7a to the second circumferential edge 7b.

[0075] Figure 8 An enlarged view of the transverse sipe 40 is shown in FIG. Figure 8 As shown, the transverse sipe 40 includes a first portion 41 extending obliquely from the first circumferential edge 7a; a second portion 42 extending obliquely from the second circumferential edge 7b in the same direction as the first portion 41; and a third portion 43 obliquely extending in the opposite direction from the first portion 41 and connecting the first and second portions 41, 42. In this embodiment, the first and second portions 41, 42 are inclined, for example, in the second direction relative to the tire axial direction, while the third portion 43 is inclined in the first direction relative to the tire axial direction. Furthermore, in this embodiment, the first interrupted groove 33, the second interrupted groove 34, the first connecting sipe 37, and the second connecting sipe 38 are inclined in the second direction relative to the tire axial direction.

[0076] When the tread is viewed from above, the first portion 41 is parallel to a projection area 55 (in the plane) obtained by extending the first connecting sipe 37 or the second connecting sipe 38 in parallel with the tire axial direction. Figure 8(The second portion 42 overlaps with a projected area 55 formed by extending the first connecting sipe 37 or the second connecting sipe 38 parallel to the tire axial direction.) In this embodiment, the above-described structure improves performance on ice and snow while suppressing a decrease in handling stability on dry roads. The reason for this is presumably the following mechanism.

[0077] In this embodiment, the first interrupted grooves 33 and first communicating sipes 37, as well as the second interrupted grooves 34 and second communicating sipes 38, provide edge components while suppressing a decrease in the rigidity of the second land portion 7. This improves performance on ice and snow while suppressing a decrease in steering stability on dry roads.

[0078] Furthermore, the transverse sipes 40 provide friction in multiple directions through their edge components, thereby maintaining performance on ice and snow. Furthermore, when the sipe walls come into contact, the transverse sipes prevent the land portion from tipping over, thereby improving braking performance on dry roads.

[0079] Moreover, in this embodiment, the first portion 41 and the second portion 42 of the transverse sipe 40 overlap with the above-mentioned projected area 55, so the sipes cooperate with each other to provide greater friction in the tire axial direction, thereby improving the cornering performance on ice and snow.

[0080] like Figure 7 As shown, the angle of the first interrupted groove 33 and the first connected sipe 37 relative to the tire axial direction is, for example, 15 to 55 degrees, preferably 30 to 50 degrees. Such first interrupted groove 33 and first connected sipe 37 can improve the braking performance and cornering performance on ice and snow in a balanced manner.

[0081] First interrupted groove 33, for example, is interrupted without intersecting the axial center of second land portion 7. The axial length of first interrupted groove 33 is shorter than the axial length of first portion 41 of transverse sipe 40. Axial length L9 of first interrupted groove 33 is, for example, 25% to 45% of axial width W3 of second land portion 7, preferably 30% to 40%. This first interrupted groove 33 helps to balance braking performance on dry roads and on ice and snow.

[0082] The depth of the first interrupted groove 33 is, for example, 60% to 80% of the depth of the crown circumferential groove 4. This improves the steering stability on dry roads and the performance on ice and snow in a balanced manner.

[0083] From the same viewpoint, the depth of the first communicating sipe 37 is preferably smaller than the depth of the first interrupted groove 33. The depth of the first communicating sipe 37 is, for example, 40% to 55% of the depth of the crown circumferential groove 4.

[0084] The second interrupted groove 34 has substantially the same structure as the first interrupted groove 33, and the structure described above for the first interrupted groove 33 can be applied to the second interrupted groove 34. The second connecting sipe 38 has substantially the same structure as the first connecting sipe 37, and the structure described above for the first connecting sipe 37 can be applied to the second connecting sipe 38.

[0085] The transverse sipe 40 is located between the first interrupted groove 33 and the second interrupted groove 34. More specifically, the transverse sipe 40 is provided between the first cutout element 28 formed by the first interrupted groove 33 and the first connecting sipe 37, and the second cutout element 29 formed by the second interrupted groove 34 and the second connecting sipe 38.

[0086] Transverse sipe 40, for example, an imaginary straight line connecting its ends, is inclined in a second direction relative to the tire axial direction. The angle between first portion 41 and second portion 42 relative to the tire axial direction is, for example, 15 to 55 degrees, preferably 40 to 50 degrees. In this embodiment, the angle difference between first portion 41 and first interrupted groove 33 is 5 degrees or less, and the angle difference between second portion 42 and second interrupted groove 34 is 5 degrees or less. This prevents uneven wear of second land portion 7.

[0087] Third portion 43 intersects, for example, the axial center of second land portion 7. Axial length L10 of third portion 43 is 10% to 25% of axial width W3 of second land portion 7. The angle of third portion 43 relative to the tire axial direction is, for example, 40 to 60°, preferably 45 to 55°.

[0088] The angle between the first portion 41 and the third portion 43, and the angle between the second portion 42 and the third portion 43, are each preferably 80° or greater, more preferably 90° or greater, and preferably 120° or less, more preferably 110° or less. Such transverse sipes 40 can suppress uneven wear of the second land portion 7 while effectively suppressing deformation of the second land portion 7 when the sipe walls contact each other.

[0089] Figure 9 Shown in Figure 7 DD line cross-sectional view. Figure 9 As shown, third portion 43 of transverse sipe 40 has a smaller depth than first portion 41 and second portion 42. Depth d6 of third portion 43 is, for example, 55% to 75%, and preferably 60% to 70%, of the maximum depth d5 of transverse sipe 40. This third portion 43 can improve handling stability and performance on snow and ice while suppressing excessive opening of transverse sipe 40 and uneven wear of second land portion 7.

[0090] In a more preferred embodiment, the maximum depth d7 of the first portion 41 is greater than the maximum depth of the first connecting sipe 37. The maximum depth d7 of the first portion 41 is 140% to 160% of the maximum depth of the first connecting sipe 37. Similarly, the maximum depth d8 of the second portion 42 is greater than the maximum depth of the second connecting sipe 38. The maximum depth d8 of the second portion 42 is 140% to 160% of the maximum depth of the second connecting sipe 38. As a result, the edges of the first and second portions 41, 42 can provide greater friction, improving performance on ice and snow.

[0091] like Figure 7 and Figure 8 As shown, the transverse sipe 40 includes first transverse sipes 40A and second transverse sipes 40B alternating along the tire circumferential direction. At least 50% of the length of the first portion 41 of the first transverse sipe 40A overlaps with the projected area 55, and at least 50% of the length of the second portion 42 overlaps with the projected area 55. At least 50% of the length of the first portion 41 of the second transverse sipe 40B overlaps with the projected area 55, and less than 50% of the length of the second portion 42 overlaps with the projected area 55. This improves both steering stability and performance on snow and ice in a balanced manner.

[0092] To reliably exhibit the above-described effects, in this embodiment, the first transverse sipe 40A preferably has at least 60% of the length of the first portion 41, more preferably at least 80%, overlap with the projected area 55. The same applies to the second portion 42 of the first transverse sipe 40A. Furthermore, the second transverse sipe 40B preferably has at most 40% of the length of the first portion 41, more preferably at most 30% overlap with the projected area 55. The same applies to the second portion 42 of the second transverse sipe 40B.

[0093] like Figure 7 As shown, in this embodiment, a first interrupted sipe 46 and a second interrupted sipe 47 are provided between the first notch element 28 and the second notch element 29. The first interrupted sipe 46 extends from the first circumferential edge 7a and has an interrupted end 46a within the tread 7s. The second interrupted sipe 47 extends from the second circumferential edge 7b and has an interrupted end 47a within the tread 7s. This arrangement of first and second interrupted sipes 46, 47 helps improve performance on ice and snow while maintaining handling stability.

[0094] The first interrupted sipe 46 is arranged on one side of the first portion 41 of the transverse sipe 40 in the tire circumferential direction, while the second interrupted sipe 47 is arranged on the other side of the second portion of the transverse sipe 40 in the tire circumferential direction. The first interrupted sipe 46 and the second interrupted sipe 47 are inclined, for example, in a second direction relative to the tire axial direction. The angles of the first interrupted sipe 46 and the second interrupted sipe 47 relative to the tire axial direction are, for example, 15 to 55 degrees. The angular difference between the first interrupted sipe 46 and the first portion 41 of the transverse sipe 40 is 5 degrees or less, and in this embodiment, they extend parallel to each other. The angular difference between the second interrupted sipe 47 and the second portion 42 of the transverse sipe 40 is 5 degrees or less, and in this embodiment, they extend parallel to each other. This arrangement of the first interrupted sipe 46 and the second interrupted sipe 47 can suppress uneven wear of the second land portion 7 while also improving traction and cornering performance on ice and snow in a balanced manner.

[0095] When viewing the tread from above, first interrupted sipe 46 overlaps with the projection of first portion 41 extended parallel to the tire's axial direction. Furthermore, second interrupted sipe 47 overlaps with the projection of second portion 42 extended parallel to the tire's axial direction. On the other hand, second interrupted sipe 47 does not overlap with the projection of first interrupted sipe 46 extended parallel to the tire's axial direction. Thus, while maintaining the rigidity of second land portion 7, the sipes cooperate to provide high friction on ice and snow.

[0096] The axial length of the first interrupted sipe 46 is, for example, less than the axial length of the first portion 41 of the transverse sipe 40, and preferably less than the axial length of the first interrupted groove 33. Similarly, the axial length of the second interrupted sipe 47 is, for example, less than the axial length of the second portion 42 of the transverse sipe 40, and preferably less than the axial length of the second interrupted groove 34. Specifically, the axial length L13 of the first interrupted sipe 46 or the second interrupted sipe 47 is 20% to 35% of the axial width W3 of the second land portion 7. These first interrupted sipes 46 and second interrupted sipes 47 effectively maintain the rigidity of the second land portion 7, and particularly, effectively maintain braking performance on dry roads.

[0097] To improve performance on snow and ice while maintaining handling stability, the maximum depth of the first interrupted sipe 46 is greater than the depth of the third portion 43 of the transverse sipe 40, and is 90% to 110% of the maximum depth of the transverse sipe 40. Furthermore, the maximum depth of the first interrupted sipe 46 is less than the maximum depth of the first connecting sipe 37 and the maximum depth of the second connecting sipe 38.

[0098] Similarly, the maximum depth of the second interrupted sipe 47 is greater than the depth of the third portion 43 of the transverse sipe 40 and is 90% to 110% of the maximum depth of the transverse sipe 40. Furthermore, the maximum depth of the second interrupted sipe 47 is less than the maximum depth of the first connecting sipe 37 and the maximum depth of the second connecting sipe 38.

[0099] Figure 10 FIG shows an enlarged view of the third land portion 8. Figure 10 As shown, the third land portion 8 is provided with a plurality of lateral grooves 49 that traverse the third land portion 8 and a plurality of zigzag sipes 50 that extend in a zigzag shape.

[0100] The zigzag sipes 50 include first zigzag sipes 51 extending from the shoulder circumferential groove 5 and interrupted within the third land portion 8; and second zigzag sipes 52 extending from the tread end Te and interrupted within the third land portion. These first zigzag sipes 51 and second zigzag sipes 52 contribute to increasing the apparent rigidity of the third land portion 8 when the facing sipe walls contact each other, thereby improving both steering stability and performance on snow and ice in a balanced manner.

[0101] As mentioned above, the pneumatic tire according to one embodiment of the present invention has been described in detail. However, the present invention is not limited to the above-described specific embodiment, and can be implemented in various modified forms.

[0102] [Example]

[0103] Trial-produced Figure 1 The basic pattern of the pneumatic tire is 215 / 60R16. In addition, the first deep bottom and the second deep bottom of each embodiment are formed with the same depth, and the first shallow bottom and the second shallow bottom are formed with the same depth. As a comparative example, a tire with Figure 1 Pneumatic tires with a basic tread pattern and a constant sipe depth (5.5 mm) along their length were tested for braking and cornering performance on ice and snow, as well as handling stability on dry roads. The general specifications and testing methods for each test tire are as follows.

[0104] Installed rim: 16×6J

[0105] Tire internal pressure: 240kPa

[0106] Test vehicle: 2400cc displacement, front-wheel drive

[0107] Tire installation position: all wheels

[0108] Braking and cornering performance on ice and snow

[0109] The driver's sensory perception was used to evaluate braking and cornering performance on ice and snow. The results were scored, with the comparative example set to 100. Higher scores indicate superior braking or cornering performance on ice and snow. The sum of the braking and cornering scores represents the overall performance on ice and snow.

[0110] <Handling stability on dry roads>

[0111] The steering stability when traveling on a dry road was evaluated using the driver's senses. The results are shown as scores, with the comparative example being 100, and larger values indicate better steering stability on a dry road.

[0112] The test results are shown in Tables 1 and 2.

[0113]

Table 1

[0114]

[0115]

Table 2

[0116]

[0117] The test results confirmed that the tires of the examples improved handling stability on dry roads and performance on ice and snow.

Claims

1. A tire having a tread portion, The tire is characterized in that The tread portion includes a plurality of circumferential grooves extending continuously in the tire circumferential direction and at least one first land portion defined by the circumferential grooves. The first land portion includes a first circumferential edge, a second circumferential edge, and a tread surface therebetween. A plurality of inclined sipes are provided on the tread along the circumferential direction of the tire, wherein the inclined sipes are inclined in a first direction relative to the axial direction of the tire. The inclined sipes include a first inclined sipe and a second inclined sipe adjacent to each other in the tire circumferential direction. The first inclined sipes include: a first deep bottom portion disposed on the first circumferential edge side; and a first shallow bottom portion that is disposed on the second circumferential edge side and has a depth smaller than that of the first deep bottom portion, The second inclined sipe includes: a second deep bottom portion disposed on the second circumferential edge side; and a second shallow bottom portion that is disposed on the first circumferential edge side and has a depth smaller than that of the second deep bottom portion, The second deep bottom portion is arranged at a position overlapping with a projection area obtained by extending the first deep bottom portion parallel to the tire axial direction.

2. The tire according to claim 1, wherein The first land portion is disposed on the tire equator.

3. The tire according to claim 1 or 2, characterized in that The angle of the inclined sipe relative to the tire axial direction is 15 to 55 degrees.

4. The tire according to claim 1 or 2, characterized in that The oblique sipes extend from the first circumferential edge to the second circumferential edge.

5. The tire according to claim 1 or 2, characterized in that A first short groove and a second short groove are provided in the first land portion. The first short groove extends from the first circumferential edge and is interrupted in the first land portion. The second short groove extends from the second circumferential edge and is interrupted in the first land portion.

6. The tire according to claim 5, characterized in that The first short groove and the second short groove are inclined toward a second direction opposite to the first direction.

7. The tire according to claim 1 or 2, characterized in that A first short groove, a second short groove, and a connecting sipe are provided in the first land portion. The first short groove extends from the first circumferential edge and is interrupted in the first land portion. The second short groove extends from the second circumferential edge and is interrupted in the first land portion. The connecting sipe extends from the first short groove to the second short groove.

8. The tire according to claim 7, characterized in that The maximum depth of the connecting sipe is smaller than the maximum depth of the first deep bottom and the maximum depth of the second deep bottom.

9. The tire according to claim 1 or 2, characterized in that The tread portion includes a second land portion adjacent to the first land portion, The second land portion includes a first circumferential edge, a second circumferential edge, and a tread surface therebetween. A plurality of transverse sipes are provided on the tread surface of the second land portion, and the transverse sipes extend from the first circumferential edge to the second circumferential edge.

10. The tire according to claim 9, characterized in that The transverse sipe includes a first portion connected to the first circumferential edge and inclined in a second direction opposite to the first direction; a second portion connected to the second circumferential edge and inclined in the second direction; and a third portion inclined in the first direction between the first portion and the second portion.

Images