TIRES

Abstract

A tire is provided that can offer improved performance on snow without compromising wear resistance. The tread section (1) is provided with a central rib section (12c), intermediate rib sections (12m), and shoulder rib sections (12s), defined by four main grooves (11) extending linearly along the tire's circumference. The central rib section (12c) is subdivided into a plurality of central blocks (14c) by inclined central grooves (13c). The intermediate rib sections (12m) are each subdivided into a plurality of intermediate blocks (14m) by inclined intermediate grooves (13m).The shoulder rib sections (12s) are provided with a narrow shoulder circumference groove (20), a first shoulder transverse groove (21) that connects to the narrow shoulder circumference groove (20) without reaching the main groove (11), and a second shoulder transverse groove (22) that opens towards the main groove (11), crosses the narrow shoulder circumference groove (20), and terminates within the rib section. The main sections of the central blocks (14c), the intermediate blocks (14m), and the shoulder rib sections (12s) are each provided with two or more sipes (16) extending along the tire width direction.

Description

Technical field

[0001] The present invention relates to a tire having a block-based tread pattern, and in particular to a tire that can provide improved performance on snow without compromising wear resistance. State of the art

[0002] For vehicles like SUVs, so-called "highway-terrain tires" are a tire category specifically designed for high-speed driving. Tires in this category must have a block-based tread pattern and be able to handle various road surface conditions (dry, wet, and snowy) (see, for example, patent document 1). In recent years, particular emphasis has been placed on high performance on snow (steering stability on snow-covered surfaces).For example, increasing the groove area increases the likelihood of snow retention, which can improve performance on snow; however, as described above, tires in this category are block-based, so increasing the groove area tends to decrease the stiffness of the rib section, and thus sufficient wear resistance cannot be readily guaranteed. Therefore, measures are needed that improve performance on snow without compromising wear resistance. List of literature on patent literature

[0003] Patent Document 1: JP 2019-137218 A Brief description of the invention: Technical problem

[0004] One object of the present invention is to provide a tire that can provide improved performance on snow without compromising wear resistance. Solution to the problem

[0005] A tire according to one embodiment of the present invention for fulfilling the problem described above is a tire that includes a tread section extending in the circumferential direction and having an annular shape. The tread section includes four main grooves extending linearly along the circumferential direction and five rows of rib sections defined by these four main grooves. These five rows of rib sections include a central rib section located at the tire equator, intermediate rib sections arranged on both sides of the central rib section in the tire width direction, and shoulder rib sections located at the outermost sides in the tire width direction. The central rib section is subdivided into a plurality of central blocks by inclined central grooves formed at intervals in the circumferential direction.The intermediate rib sections are subdivided into a multitude of intermediate blocks by inclined intermediate grooves spaced at intervals along the tire's circumference. A narrow shoulder circumferential groove, extending along the tire's circumference parallel to a main groove located at the outermost sides in the tire's width direction, and a first shoulder transverse groove and a second shoulder transverse groove, also extending in the tire's width direction, are formed within each shoulder rib section. The first shoulder transverse groove has an outer end in the tire's width direction that opens beyond a ground contact edge and an inner end in the tire's width direction that connects to and terminates at the narrow shoulder circumferential groove without reaching the main groove.The second shoulder cross groove has a groove width smaller than that of the first shoulder cross groove, extends inclined in the direction of the tire's width, and has an inner end in the direction of the tire's width that connects to the main groove and an outer end in the direction of the tire's width that crosses the narrow shoulder cross groove and terminates in the shoulder rib sections. Two or more sipes extending in the direction of the tire's width are formed at intervals in the direction of the tire's circumference in each of the central blocks and the intermediate blocks. The two or more sipes extending in the direction of the tire's width are formed at intervals in the direction of the tire's circumference in a specific area surrounded by the narrow shoulder circumferential groove and a pair of the first shoulder cross grooves that are adjacent to each other in the direction of the tire's circumference in the shoulder rib section. Advantageous effects of the invention

[0006] The tire according to one embodiment of the present invention has the tread pattern configured as described above, so that performance on snow can be improved without compromising wear resistance. Since the four main grooves extend linearly, as described above, the stiffness of the end sections of the blocks described below in the lateral direction, as well as wear resistance and resistance to uneven wear, can be ensured. The grooves (the inclined central groove and the inclined intermediate groove) that define the central rib section and the intermediate rib section are inclined with respect to the tire's lateral direction, thus improving performance on snow.Furthermore, the shoulder rib sections incorporate the narrow shoulder circumferential groove, the first shoulder transverse groove, and the second shoulder transverse groove. Performance on snow is ensured by the first shoulder transverse groove. The first shoulder transverse groove does not reach the main groove but connects to and terminates at the narrow shoulder circumferential groove. Thus, a rib section extending continuously across essentially the entire circumference of the tire is formed between the main groove on the outermost side (in the tire width direction) and the narrow shoulder circumferential groove, thereby ensuring block stiffness. Although the second shoulder transverse groove extends beyond the narrow shoulder circumferential groove from the main groove in the tire width direction, its width is narrower than that of the first shoulder transverse groove, and therefore block stiffness is not compromised.Therefore, a further improvement in snow performance can be expected from the second shoulder groove. Since each block also features an appropriate number of sipes extending along the tire's width, snow performance can be enhanced. The interaction of these factors ensures a highly compatible balance between wear resistance and snow performance.

[0007] In one embodiment of the present invention, the first shoulder transverse groove preferably has its inner end (in the direction of tire width) tapered towards the narrow shoulder circumferential groove, with the groove width decreasing. The first shoulder transverse groove, which thus has a tapered shape, can counteract the reduction in stiffness of the shoulder rib sections (particularly near the narrow shoulder circumferential groove) resulting from the design of the first shoulder transverse groove. This is advantageous for ensuring wear resistance.

[0008] In one embodiment of the present invention, a groove depth Dc of the narrow shoulder circumference groove, a groove depth D1 of the first shoulder transverse groove, and a groove depth D2 of the second shoulder transverse groove preferably satisfy a ratio Dc ≤ D2 < D1. This improves the balance between the performance on snow added by the grooves and the block stiffness reduced by the formation of the grooves, and is therefore advantageous for achieving both performance on snow and wear resistance in a compatible manner.

[0009] In one embodiment of the present invention, a flat central groove, extending in the same direction as the inclined intermediate groove and terminating within each of the central blocks without crossing the tire's equator, is preferably formed at an extension position of the inclined intermediate groove in each of the central blocks. By providing the flat central groove, extending in the same direction as the inclined intermediate groove, at the extension position of the inclined intermediate groove, the inclined intermediate groove and the flat central groove function as a continuous groove, thus improving performance on snow.On the other hand, the shallow central groove has a shallower groove depth than the main groove and ends within the central block without crossing the tire equator, and therefore a reduction in block stiffness due to the provision of the shallow central grooves can be suppressed, thus ensuring wear resistance.

[0010] In one embodiment of the present invention, a shallow intermediate groove, opening towards the main groove located on the outermost side in the tire width direction, extending in the same direction as the inclined intermediate groove and terminating within the intermediate block without crossing its center in the tire width direction, is preferably formed between the adjacent sipes in the intermediate block in the tire circumference direction. This adds edge grip through the shallow intermediate groove, further improving performance on snow. Furthermore, the shallow intermediate groove has a shallower groove depth than the main groove and terminates blindly within the intermediate block without crossing its center. Therefore, a reduction in block stiffness due to the shallow intermediate grooves can be suppressed, thus ensuring wear resistance.

[0011] In one embodiment of the present invention, a raised base section is preferably provided at the bottom of each of the inclined central grooves and the inclined intermediate grooves. Providing a raised base section in this way allows the block stiffness to be maintained without reducing the groove area. This is advantageous for achieving both performance on snow and wear resistance.

[0012] In one embodiment of the present invention, preferably an intermediate lamella, formed in each of the intermediate blocks, extends from the lamellae in the same direction as the inclined intermediate grooves; a central lamella, formed in each of the central blocks, extends in the same direction as the inclined central grooves; and a shoulder lamella, formed in each of the shoulder web sections, extends in the same direction as the first transverse shoulder grooves. By inclined the grooves and lamellae in each block in the same direction in this way, block stiffness can be ensured. This is advantageous for maintaining wear resistance.

[0013] The tire according to one embodiment of the present invention is preferably a pneumatic tire, but can also be a non-pneumatic tire. In the case of a pneumatic tire, its interior can be filled with air, an inert gas such as nitrogen, or another gas. Brief description of the drawings Fig. Figure 1 is a meridian cross-sectional view of a tire according to an embodiment of the present invention. Fig. Figure 2 is a front view illustrating a tread surface of a tire according to an embodiment of the present invention. Fig. 3 is an explanatory view that shows an extracted part of Fig. 2 illustrated. Description of embodiments

[0014] Configurations of embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0015] If the tire according to one embodiment of the present invention is a pneumatic tire such as the one described in Fig. As illustrated in Figure 1, it includes a tread section 1 that comes into contact with a road surface, a pair of sidewall sections 2, each arranged on both sides of the tread section 1, and a pair of bead sections 3, each arranged in a tire radial direction on an inside sidewall of the pair of sidewall sections 2. Fig. Reference numeral CL (1) denotes a tire equator, and reference numeral E denotes a ground contact edge. It should be noted that the tread section (1), sidewall section (2), and bead section (3), although in Fig.Figure 1, which is a meridian cross-sectional view, is not illustrated. Each runs in the direction of the tire's circumference and has a ring shape, thus forming a basic annular structure of the pneumatic tire. Although the description using Fig. 1. Essentially based on the illustrated meridian cross-section, all tire components subsequently extend in the direction of the tire's circumference and form a ring shape.

[0016] If the tire is a pneumatic tire, the ground contact edge E is an end section in the tire's width direction of a ground contact area that forms when the tire is mounted on a normal rim, inflated to normal internal pressure, placed vertically on a flat surface, and subjected to a normal load. A "regular rim" is a rim defined for each tire by a standard according to a system of standards that includes standards met by tires. Examples include a "standard rim" as defined by the Japan Automobile Tyre Manufacturers Association Inc. (JATMA), a "design rim" as defined by the Tire and Rim Association Inc. (TRA), or a "measuring rim" as defined by the European Tyre and Rim Technical Organisation (ETRTO).In the system of standards that includes standards met by tires, "regular inflation pressure" is an air pressure defined by the respective standards for a given tire and is referred to as "maximum air pressure" in the case of JATMA, as the maximum value in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the case of TRA, and as "INFLATION PRESSURE" in the case of ETRTO. However, if a tire is a passenger car tire, the "regular inflation pressure" is 180 kPa."Regular load" is a load defined for each tire by a standard within a system of standards that includes standards on which tires are based. It refers to "maximum load capacity" in the case of JATMA, to the maximum value in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" table in the case of TRA, and to "LOAD CAPACITY" in the case of ETRTO. "Regular load" corresponds to 88% of the loads described above for a tire on a passenger car.

[0017] A carcass layer 4 is arranged between a pair of left and right bead sections 3. The carcass layer 4 encloses a plurality of reinforcing cord threads running in the tire radial direction and is folded back from an inside to an outside around a bead core 5 arranged in each of the bead sections 3. A bead filler 6 is arranged on one circumference of the bead core 5, and the bead filler 6 is enclosed by a body section and a folded-back section of the carcass layer 4. Meanwhile, in the tread section 1, a plurality of belt layers 7 (two layers in Fig.1) embedded on an outer circumferential side of the carcass layer 4. Each of these belt layers 7 encloses a plurality of reinforcing cord threads inclined with respect to the tire's circumferential direction and arranged such that the reinforcing cord threads overlap each other between the layers. In these belt layers 7, the angle of inclination of the reinforcing cord threads with respect to the tire's circumferential direction is set in a range of, for example, 10° to 40°. Furthermore, an outer circumferential side of the belt layer 7 is provided with at least one belt reinforcement layer 8 (in Fig. 1 two). The belt reinforcement layer 8 includes organic fiber cord threads oriented in the tire's circumferential direction. In the belt reinforcement layer 8, the angle of the organic fiber cord relative to the tire's circumferential direction is set, for example, to 0° to 5°.

[0018] The present invention relates to a tread pattern formed on the surface of the tread section 1 of the tire, as described below, and the basic structure (cross-sectional structure) of the tire is not limited to the general structure described above. Although the following description is based on a Fig. As illustrated in Figure 1, the present invention can be applied to various types of tires, including non-pneumatic tires, as long as the tire has a surface (a section corresponding to the surface of the tread section 1 of a pneumatic tire) that is in contact with a road surface.

[0019] The surface of the tread section 1 in the tire according to the embodiment of the present invention is provided with four main grooves 11 which extend linearly along the tire's circumferential direction, as shown in Fig.Figure 2 illustrates this. In the following description, among the four main grooves 11, a pair of main grooves arranged on either side of the tire equator CL are referred to as inner main grooves 11i, and a pair of main grooves arranged on the outer sides of the respective inner main grooves 11i in the tire width direction are referred to as outer main grooves 11o. The depth of each main groove 11, which is not specifically limited, can be specified, for example, between 7.0 mm and 16.0 mm. Since the four main grooves 11 extend linearly, as described above, the stiffness of the end sections of the rib sections 12 (blocks) in the width direction described below, as well as wear resistance and resistance to uneven wear, can be ensured.

[0020] These four main grooves 11 define five rows of rib sections 12 extending along the tire's circumference. Specifically, a central rib section 12c is defined between the pair of inner main grooves 11i, intermediate rib sections 12m are defined between the inner main grooves 11i and the outer main grooves 11o, and shoulder rib sections 12s are defined on the outer surfaces of the outer main grooves 11o in the tire's width direction. In other words, the central rib section 12c is a rib section located at the tire's equator CL, the intermediate rib sections 12m are rib sections adjacent to, i.e.,on both sides of the central rib section 12c in the direction of the tire width, with the inner main grooves 11i provided between them, and the shoulder rib sections 12s are rib sections arranged on the outermost sides in the direction of the tire width including the ground contact edges E.

[0021] The central rib section 12c is subdivided into a plurality of central blocks 14c by inclined central grooves 13c, which are formed at intervals in the circumferential direction of the tire. The intermediate rib section 12m is subdivided into a plurality of intermediate blocks 14m by inclined intermediate grooves 13m, which are formed at intervals in the circumferential direction of the tire. The inclined central groove 13c is a groove that extends inclinedly with respect to the tire width direction; furthermore, both ends are open to the pair of inner main grooves 11i, which are located on both sides of the central rib section 12c. The inclined intermediate groove 13m is a groove that extends inclinedly with respect to the tire width direction; furthermore, both ends are open to the inner main grooves 11i and the outer main groove 11o, which are located on both sides of the intermediate rib section 12m.The inclined central groove 13c and the inclined intermediate groove 13m can be inclined in opposite directions with respect to the tire width direction. Furthermore, as in the illustrated example, the inclined central groove 13c can extend linearly, while the inclined intermediate groove 13m can be curved (in the illustrated example, the inclined intermediate groove 13m has a zigzag shape, comprising a first section opening towards the inner main groove 11i and extending linearly inclined with respect to the tire width direction, a second section extending linearly in the same direction as the first section and opening towards the outer main groove 11o, and a third section connecting the first and second sections and inclined in a direction opposite to the first and second sections).In the following description, the inclined central groove 13c and the inclined intermediate groove 13m are collectively referred to as the "inclined groove". These inclined grooves can improve performance on snow. In particular, if the inclined central groove 13c and the inclined intermediate groove 13m are inclined in opposite directions, or if the inclined intermediate groove 13m has the curved shape described above, the edge effect can be exerted in different directions, and performance on snow can be effectively improved.

[0022] The inclination angle of each inclined groove can be set, for example, to 10° to 50° with respect to the tire width direction. In particular, the inclination angle θc of the inclined central grooves 13c with respect to the tire width direction can preferably be set to 10° to 50° and more preferably to 10° to 30°. An inclination angle θm of the inclined intermediate groove 13m with respect to the tire width direction can preferably be set to -10° to -50° and more preferably to -10° to -30°, if a positive value (+) is used to specify the inclination direction of the inclined central groove 13c described above. Although the inclination angle θc and the inclination angle θm can be equal, with the inclination direction (positive / negative) being reversed, the absolute value of the inclination angle θm is preferably greater than the absolute value of the inclination angle θc.The inclined intermediate groove 13m is, compared to the inclined central groove 13c as described above, steeply inclined relative to the tire width direction, thus effectively improving performance on snow. As in . Fig. As illustrated in Figure 3, the inclination angles θc and θm each represent an angle of a straight line connecting the middle points of the grooves in the width direction at the opening ends of the inclined grooves with respect to the tire width direction.

[0023] The groove depth of each inclined groove is preferably 20% to 100% and more preferably 50% to 100% of the groove depth of the main groove 11.

[0024] A narrow shoulder circumferential groove 20, extending along the tire's circumference, and a first shoulder transverse groove 21 and a second shoulder transverse groove 21, extending along the tire's width, are formed in the shoulder rib section 12s. Specifically, the narrow shoulder circumferential groove 20 extends in the tire's circumference parallel to the main groove 11, which is located on the outermost side in the tire's width direction (i.e., to the outer main groove 11o), and a continuous rib 23, extending continuously over substantially the entire tire circumference, is formed between the outer main groove 11o and the narrow shoulder circumferential groove 20. The first shoulder transverse groove 21 has an outer end in the tire's width direction that opens beyond a ground contact edge E, and an inner end in the tire's width direction that connects to the narrow shoulder circumferential groove 20.The first shoulder cross groove 21 is connected to and terminates at the narrow shoulder circumferential groove 20, and does not reach either the continuous rib 23 or the outer main groove 110. The second shoulder cross groove 22 extends inclined relative to the tire width direction, so that it intersects the narrow shoulder circumferential groove 20, and has an inner end (in the tire width direction) that connects to the outer main groove 110, and an outer end (in the tire width direction) that terminates within the shoulder rib section 12s. Since the narrow shoulder circumferential groove 20 and the second shoulder cross groove 22 have a groove width that is smaller than that of the first shoulder cross groove 21, the section defined by the narrow shoulder circumferential groove 20 and the second shoulder cross groove 22 is not fully subdivided compared to the section defined by the first shoulder cross groove 21, thus maintaining block stiffness.Performance on snow is ensured by the edge effect of each groove formed in the shoulder rib section 12s, but the continuous rib 23, as described above, is formed with the first shoulder transverse groove 21, which does not reach the outer main groove 11o, and therefore block stiffness can be ensured. In this case, the narrow shoulder circumferential groove 20 and the second shoulder transverse groove 22 have a small groove width. Although the rib section thus appears to be defined by these grooves, the block stiffness is not significantly reduced, and therefore wear resistance can be ensured.

[0025] As described above, the narrow shoulder circumference groove 20 and the second shoulder transverse groove 22 each have a groove width that is smaller than that of the first shoulder transverse groove 21, and if the groove widths of the narrow shoulder circumference groove 20, the first shoulder transverse groove 21 and the second shoulder transverse groove 22 are each defined by Gc, G1 and G2 respectively, the groove width G1 of the first shoulder transverse groove 21 is preferably 1.5 to 3.0 times, more preferably 1.8 to 2.7 times, the groove width Gc of the narrow shoulder circumference groove 20 or the groove width G2 of the second shoulder transverse groove 22. In the case of a tapered shape described below, the groove width G1 of the first shoulder transverse groove is considered to be the groove width in a main section excluding a narrow section.

[0026] Furthermore, if the groove depth of the narrow shoulder circumference groove 20, the groove depth of the first shoulder transverse groove 21, and the groove depth of the second shoulder transverse groove 22 are each defined as Dc, D1, and D2, these groove depths preferably satisfy the ratio Dc ≤ D2 < D1. This improves the balance between the performance on snow added by the grooves and the block stiffness reduced by the formation of the grooves, and is thus advantageous for achieving both performance on snow and wear resistance in a compatible manner. While the specific groove depth is not restricted, the groove depth of the first shoulder transverse groove 21 is preferably 60% to 100%, and more preferably 70% to 90%, of the groove depth of the main groove 11.The groove depth Dc of the narrow shoulder circumference groove 20 and the groove depth D2 of the second shoulder transverse groove 22 are preferably 20% to 70%, more preferably 30% to 60% of the groove depth of the main groove 11.

[0027] An angle θ1 of the first lateral shoulder groove, relative to the tire width direction, can preferably be set to 0° ± 15° and more preferably to 0° ± 10°. An inclination angle θ2 of the second transverse shoulder groove, relative to the tire width direction, can preferably be set to 10° to 50° and more preferably to 10° to 30° (if a positive value (+) is used to specify the inclination direction of the aforementioned inclined central groove 13c, preferably -10° to -50°, and more preferably -10° to -30°). These angles θ1 and θ2 are measured as angles of a straight line connecting the center of the groove in width at the opening end with the main groove 11 and the narrow shoulder circumference groove 20 with the center of the groove in width at the position of the ground contact edge E and the terminal end section, in relation to the tire width direction, as in the case of the inclination angles θc and θm.

[0028] In each of the central blocks 14c and the intermediate blocks 14m, two or more, preferably two to four, sipes 16 are formed at intervals in the circumferential direction of the tire, extending along the tire width direction. In the shoulder rib section 12s, two or more, preferably two to four, sipes 16, extending along the tire width direction, are formed at intervals in the circumferential direction of the tire in each of the areas surrounded by a pair of first shoulder transverse grooves 21, which are adjacent to each other in the circumferential direction of the tire, and the narrow shoulder circumferential groove 20. While the shape of each sipe 16 is not limited, the sipe 16 preferably has a zigzag shape on the tread surface of each block and rib section, as illustrated in the drawing.The groove width of these lamellae 16 can be set, for example, to 1.5 mm or less, and the groove depth of the lamellae 16 can be set, for example, to 50% to 100% of the groove depth of the main groove 11. Thus, the appropriate provision of the lamellae 16 in each block and rib section can effectively improve performance on snow.

[0029] Since the tire according to the embodiment of the present invention has a tread pattern configured as described above, the effects of the respective elements described above (ensuring wear resistance by the four straight main grooves 11, improving performance on snow by the inclined central groove 13c and the inclined intermediate groove 13m, maintaining wear resistance and improving performance on snow by the narrow shoulder circumferential groove 20, the first shoulder transverse groove 21 and the second shoulder transverse groove 22 provided in the shoulder rib section 12s, and improving performance on snow by the sipes 16) work together so that wear resistance and performance on snow can be achieved in a highly compatible manner.

[0030] The groove width of the first shoulder transverse grooves 21 need not be constant, and at least some, and preferably all, of the plurality of first shoulder transverse grooves 21 have an inner end (in the direction of tire width) that tapers towards the narrow shoulder circumference groove 20, with the groove width decreasing. The tapered shape can be a structure in which the groove width converges towards the tip of the groove (V-shaped end section), or a shape that includes a narrow-width section with a narrow groove width at a section connected to the narrow shoulder circumference groove 20 and a connecting section with a groove width that gradually decreases from the main section of the first shoulder transverse groove 21 to the narrow-width section, as in the illustrated example.When the narrow-width section is provided as in the illustrated example, the groove width of the narrow-width section is preferably 0.5 to 2.0 times the groove width of the shoulder circumferential groove 20. The length of the narrow-width section is preferably 0% to 30% of the tire width direction length from the shoulder circumferential groove 20 to the ground contact edge E. By thus having a tapered shape, the reduction in stiffness of the shoulder rib section 12s (particularly near the narrow shoulder circumferential groove 20) due to the design of the first shoulder transverse groove 21 can be suppressed. This is advantageous for ensuring wear resistance. The narrow-width section of the first shoulder transverse groove 21 described above may be raised from the main section of the first shoulder transverse groove 21.

[0031] At an extension position of the inclined intermediate groove 13m in the central block 14c, a flat central groove 15c can be formed, extending in the same direction as the inclined intermediate groove 13m and terminating within the central block 14c without crossing the tire equator CL. The flat central groove 15c is a groove with a shallower depth than the main groove 11 or the inclined groove (especially the inclined intermediate groove 13m), and its depth is preferably set to 10% to 80%, more preferably 30% to 60%, of the groove depth of the main groove 11. The extension position of the inclined intermediate groove 13m is a position of overlap between an area (hatched section in Fig. 3) between extension lines (dashed lines in Fig.3) the groove walls of the inclined intermediate groove 13m and at least part of the opening end. By providing the flat central groove 15c in this way, the inclined intermediate groove 13m and the flat central groove 15c function as a continuous groove, thus improving performance on snow. On the other hand, the flat central groove 15c has a shallower groove depth than the main groove 11 and ends within the central block 14c without crossing the tire equator CL, and therefore a reduction in block stiffness due to the provision of the flat central grooves 15c can be suppressed, thus ensuring wear resistance.

[0032] Although the shape of the flat central groove 15c is not restricted, at least some and preferably all of the plurality of flat central grooves 15c taper, preferably towards the narrow shoulder circumference groove, with the groove width decreasing. The tapered shape can be a structure in which the groove width converges towards the tip of the groove (V-shaped end section), or a shape that includes a narrow-width section with a narrow groove width at the terminal end section and a connecting section with a groove width that gradually decreases from the main section of the flat central groove 15c to the narrow-width section, as in the illustrated example. Thus, providing the flat central groove 15c with a tapered shape can counteract the reduction in stiffness of the central block 14c due to the formation of the flat central groove 15c.This is advantageous for ensuring wear resistance.

[0033] In the intermediate block 14m, a shallow intermediate groove 15m can be formed between the adjacent sipes 16 in the circumferential direction of the tire. This groove opens towards the main groove 11 (outer main groove 11o) located on the outermost side in the tire width direction, extends in the same direction as the inclined intermediate groove 13m, and terminates within the intermediate block 14m without crossing the center of the intermediate block in the tire width direction. The shallow intermediate groove 15m is a groove with a shallower depth than the main groove 11 or the inclined groove (especially the inclined intermediate groove 13m), and its depth is preferably set to 10% to 80%, more preferably 30% to 60%, of the depth of the main groove 11. The shallow groove provided (15m) complements the edge effect through the shallow intermediate groove (15m) and further improves performance on snow.On the other hand, the shallow intermediate groove 15m has a shallower groove depth than the main groove 11 and ends within the intermediate block 14m without crossing the center of the intermediate block 14m, and therefore a reduction in block stiffness due to the provision of the shallow intermediate grooves 15m can be suppressed, thus ensuring wear resistance.

[0034] The lamellae 16 formed in the blocks (the central block 14c and the intermediate block 14m) and the bridge section (shoulder bridge section 12s) preferably extend in the same direction as the grooves (the inclined central groove 13c, the inclined intermediate groove 13m, and the first shoulder transverse groove 21) that define the blocks or the bridge section. In particular, the intermediate lamella 16m formed in the intermediate block 14m can extend in the same direction as the inclined intermediate groove 13m, the central lamella 16c formed in the central block 14c can extend in the same direction as the inclined central lamella 13c, and a shoulder lamella 16s formed in the shoulder bridge section 12s can extend in the same direction as the first shoulder transverse groove 21.Thus, the block stiffness is ensured by the fact that the grooves extending in the width direction and the lamellae 16 in each block or web section extend substantially parallel to each other. This is advantageous for maintaining wear resistance. If the inclination directions of these grooves and the lamellae 16 are opposite to each other, it becomes difficult to effectively maintain the block stiffness. In each block, the angular difference between the groove extending in the width direction (the inclined central groove 13c, the inclined intermediate groove 13m, the first shoulder transverse groove 21) and the lamella (the central lamella 16c, the intermediate lamella 16m, the shoulder lamella 16s) can preferably be 0° to 10° and more preferably 0° to 5°.

[0035] In the embodiment of the present invention, a raised bottom section A can be provided at the bottom of each of the inclined central groove 13c, the inclined intermediate groove 13m, and the first shoulder transverse groove 21. The raised bottom section A is a section in which the groove bottom is raised compared to the other section in a portion of each groove. The raised bottom section A can be provided at a position where each groove connects with a groove (the main groove 11 or the narrow shoulder circumferential groove 20) that extends along the tire's circumferential direction. When the raised bottom section A is provided at the position of connection with the main groove 11, the elevation of the raised bottom section A can preferably be 20% to 80%, and more preferably 40% to 60%, of the depth of the main groove 11.When the raised bottom section A is positioned where it interacts with the narrow shoulder circumference groove 20, the groove depth of the raised bottom section A can be equal to or less than that of the narrow shoulder circumference groove 20, and in particular, the raised section can preferably be 10% to 50%, more preferably 20% to 30%, of the depth of the main groove 11. The raised section is the height from the bottom of the groove in which the raised bottom section A is formed to the upper surface of the raised bottom section A. Providing the raised bottom section A in this way can maintain block stiffness without reducing the groove area. This is advantageous for achieving both snow performance and wear resistance.If the elevation falls below the range specified above, there is no significant difference compared to the case where the raised soil section A is not present, and sufficient effectiveness of the raised soil section A cannot be expected. If the elevation exceeds the range specified above, the groove depth in the area where the raised soil section A is provided can no longer be adequately guaranteed, and therefore, ensuring sufficient performance on snow becomes difficult.

[0036] The present invention is further described below with reference to examples, but the scope of the present invention is not limited to these examples. Example

[0037] Eight types of pneumatic tires were manufactured according to the prior art example 1, comparative example 1 and examples 1 to 6, each of which had the size 265 / 70R17 115H, which in Fig.1 illustrated basic structure (cross-sectional structure), and in which the inclination angle θc of the inclined central groove, the inclination angle θm of the inclined intermediate groove, the presence of a narrow shoulder circumference groove, the presence of a first shoulder transverse groove, the presence of a second shoulder transverse groove, the number of lamellae in each bridge section (central block, intermediate block, shoulder bridge section), the groove depth of each groove formed in the shoulder bridge section (narrow shoulder circumference groove, first shoulder transverse groove, second shoulder transverse groove), the shape of the first shoulder transverse groove, the presence of a shallow central groove, the presence of a shallow intermediate groove, the presence of a raised bottom section in each inclined groove (inclined central groove, inclined intermediate groove), and the angle difference between the groove (inclined central groove, inclined intermediate groove,first shoulder transverse groove) and the lamella in each block or bridge section as specified in Table 1.

[0038] In each example, four linear main grooves were provided. The angle of the first shoulder cross groove with respect to the tire width direction was 0°, and the angle, in the case of the provision of the second shoulder cross groove, was the same as the angle θm of the inclined intermediate groove. The groove width of the narrow shoulder circumference groove was 2 mm, the groove width of the first shoulder cross grooves was 5 mm, and the groove width of the second shoulder cross groove was 2 mm. The groove width of the narrow-width section of the first shoulder cross groove with a tapered shape was 2 mm. Prior art example 1 is a pattern in which the narrow shoulder circumference groove and the second shoulder cross groove are not provided, and the shoulder rib section is divided into a plurality of blocks by the first shoulder cross groove and has a structure that constitutes the "continuous rib" as in Fig. does not include 2.

[0039] In the rows “Angle θc of inclined central groove” and “Angle θm of inclined intermediate groove” in Table 1, the angle θc of the inclined central groove is indicated by a positive (+) value (a negative (-) value means that the inclined central groove is inclined in the opposite direction to the inclined central groove). The row “Number of sipes in shoulder rib section” shows the number of sipes in each block when the shoulder rib section is divided into a plurality of blocks (Example of the State of the Art 1), and in Examples 1 to 6 shows the number of sipes enclosed in an area surrounded by a pair of first transverse shoulder grooves adjacent to each other in the circumferential direction of the tire and a narrow circumferential shoulder groove.Comparative Example 1 does not include the first shoulder transverse groove and therefore does not include the area defined as in Examples 1 to 6, but the arrangement of the lamellae is the same as in Examples 1 to 6, except that no first shoulder transverse groove is provided. Therefore, the values ​​corresponding to Examples 1 to 6 are provided in parentheses for reference. The "Groove Depth" row indicates a ratio (%) to the depth of the main groove. The "First Shoulder Transverse Groove Shape" row indicates "Constant Width" if the groove width is constant and "Tapered" in the case of a tapered shape. Regarding the "Presence of a Raised Bottom Section" row, "Yes" in an example means that the raised bottom section and the narrower section are provided in each groove, as shown in [reference missing]. Fig. 2 illustrated.

[0040] The pneumatic tires were evaluated for their performance on snow and their wear resistance using an evaluation procedure described below, the results of which are shown in Table 1. Performance on snow

[0041] The respective test tires were mounted on wheels with a rim size of 17 × 8J and fitted to a test vehicle (SUV with all-wheel drive) with a tire pressure of 230 kPa in both the front and rear tires. A test driver then performed a sensory evaluation of the steering stability on a test track with a snow-covered surface. Evaluation results are expressed as index values, with the state-of-the-art example 1 being assigned an index value of 100. Higher index values ​​indicate excellent performance on snow. Wear resistance

[0042] The respective test tires were mounted on wheels with a rim size of 17 × 8J and fitted to a test vehicle (SUV with all-wheel drive) with a tire pressure of 230 kPa in both the front and rear tires. A test driver then performed a driving test on a test track to measure the distance traveled (unit: km) until complete wear. Evaluation results are expressed as index values, with the state-of-the-art example 1 being assigned an index value of 100. A higher index value indicates a longer mileage until complete wear and signifies better wear resistance. [Table 1-I] State of the art example 1 Comparative example 1 Example 1 Example 2 Angle θc of the inclined central groove +20° +15° +15° +15° Angle θm of the inclined intermediate groove -20° -25° -25° -25° Presence of a narrow shoulder circumference groove No Yes Yes Yes Presence of the first shoulder transverse groove Yes No Yes Yes Presence of the second shoulder transverse groove No Yes Yes Yes Number of slats Central block 0 2 2 2 Intermediate block 0 4 4 4 Shoulder strap section 0 (3) 3 3 Groove depth Narrow shoulder groove - 70 % 70 % 70 % First shoulder groove 100 % - 100 % 100 % Second shoulder groove - 100 % 100 % 100 % Shape of the first transverse shoulder groove Constant width - Constant width Rejuvenated Presence of the flat central groove No No No No Presence of the flat intermediate groove No No No No Presence of an elevated section of ground Inclined central groove No No No No Inclined intermediate groove No No No No Angle difference between each groove and lamella Central block - 20° 20° 20° Intermediate block - 20° 20° 20° Shoulder strap section - 20° 20° 20° Performance on snow (index value) 100 96 106 105 Wear resistance (index value) 100 102 100 103 [Table 1-II] Example 3 Example 4 Example 5 Example 6 Angle θc of the inclined central groove +15° +15° +15° +15° Angle θm of the inclined intermediate groove -25° -25° -25° -25° Presence of a narrow shoulder circumference groove Yes Yes Yes Yes Presence of the first shoulder transverse groove Yes Yes Yes Yes Presence of the second shoulder transverse groove Yes Yes Yes Yes Number of slats Central block 2 2 2 2 Intermediate block 4 4 4 4 Shoulder strap section 3 3 3 3 Groove depth Narrow shoulder groove 30 % 30 % 30 % 30 % First shoulder groove 90 % 90 % 90 % 90 % Second shoulder groove 70 % 70 % 70 % 70 % Shape of the first transverse shoulder groove Rejuvenated Rejuvenated Rejuvenated Rejuvenated Presence of the flat central groove No Yes Yes Yes Presence of the flat intermediate groove No Yes Yes Yes Presence of an elevated section of ground Inclined central groove No No Yes Yes Inclined intermediate groove No No Yes Yes Angle difference between each groove and lamella Central block 20° 20° 20° 0° Intermediate block 20° 20° 20° 0° Shoulder strap section 20° 20° 20° 0° Performance on snow (index value) 104 105 104 104 Wear resistance (index value) 106 105 106 107

[0043] As can be seen from Table 1, the pneumatic tires of Examples 1 to 6 exhibited improved snow performance and wear resistance compared to the prior art example 1, and provided these performance levels in a balanced and compatible manner. On the other hand, in comparison example 1, where the shoulder rib section includes the narrow shoulder circumferential groove and the second shoulder transverse groove, but not the first shoulder transverse groove, snow performance was impaired. List of reference symbols 1 tread section 2 Side wall section 3 bead section 4 Carcass layer 5 bead core 6 bead fillers 7th belt layer 8 Belt reinforcement layer 11 Main groove 11i inner main groove 11o outer main groove 12 Bridge section 12c central bridge section 12m intermediate walkway section 12s shoulder strap section 13c inclined central groove 13m inclined intermediate groove 14c Central block 14m intermediate block 15 flat groove 16 lamellae 16c Central lamella 16m intermediate slat 16s shoulder plate 20 narrow shoulder groove 21 first transverse shoulder groove 22 second shoulder transverse groove 23 continuous rib A raised section of ground B narrow section CL tire equator E Ground contact edge QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2019-137218 A

[0003]

Claims

A tire comprising a tread section extending in a circumferential direction and having an annular shape, wherein the tread section comprises four main grooves extending linearly along the circumferential direction of the tire and five rows of rib sections defined by these four main grooves, wherein these five rows of rib sections comprise a central rib section located at a tire equator, intermediate rib sections located on both sides of the central rib section in the tire width direction, and shoulder rib sections located at the outermost sides in the tire width direction, wherein the central rib section is subdivided into a plurality of central blocks by inclined central grooves formed at intervals in the circumferential direction of the tire, wherein the intermediate rib sections are each divided by inclined intermediate grooves formed at intervals in the tire circumference direction.are divided into a multitude of intermediate blocks, wherein a narrow shoulder circumferential groove extends along the tire circumferential direction parallel to a main groove of the main grooves, which is arranged at the outermost sides in the tire width direction, and wherein a first shoulder transverse groove and a second shoulder transverse groove extend along the tire width direction and are formed in a shoulder rib section of the shoulder rib sections, wherein the first shoulder transverse groove has an outer end in the tire width direction that opens beyond a ground contact edge, and an inner end in the tire width direction that is connected to and terminates at the narrow shoulder circumferential groove without reaching the main groove, wherein the second shoulder transverse groove has a groove width that is smaller than that of the first shoulder transverse groove, extends inclined with respect to the tire width direction, and has an inner end in the tire width direction.which is connected to the main groove, and has an outer end in the tire width direction that crosses the narrow shoulder transverse groove and terminates in the shoulder rib section, wherein two or more sipes extending along the tire width direction are formed at intervals in the tire circumferential direction in each of the central blocks and the intermediate blocks, wherein the two or more sipes extending along the tire width direction are formed at intervals in the tire circumferential direction in an individual area surrounded by the narrow shoulder circumferential groove and a pair of the first shoulder transverse grooves that are adjacent to each other in the shoulder rib section in the tire circumferential direction. Tire according to claim 1, wherein the first shoulder transverse groove has the inner end in the tire width direction that tapers towards the narrow shoulder circumferential groove, wherein the groove width decreases. Tires according to claim 1 or 2, wherein a groove depth Dc of the narrow shoulder circumference groove, a groove depth D1 of the first shoulder transverse groove and a groove depth D2 of the second shoulder transverse groove satisfy a ratio Dc ≤ D2 < D1. Tires according to one of claims 1 to 3, wherein a flat central groove extending in the same direction as the inclined intermediate groove and ending within each of the central blocks without crossing the tire equator is formed at an extension position of the inclined intermediate groove in each of the central blocks. Tires according to one of claims 1 to 4, wherein a flat intermediate groove is formed between the sipes adjacent to each other in the intermediate block in the circumferential direction of the tire, which opens towards the main groove arranged on the outermost side in the tire width direction, extends in the same direction as the inclined intermediate groove and ends within the intermediate block without crossing a center of each of the intermediate blocks in the tire width direction. Tires according to one of claims 1 to 5, wherein a raised floor section is provided on each of the inclined central grooves and the inclined intermediate grooves at a groove bottom. Tires according to one of claims 1 to 6, wherein an intermediate sipe formed in each of the intermediate blocks extends in the same direction as the inclined intermediate grooves, a central sipe formed in each of the central blocks extends in the same direction as the inclined central grooves, and a shoulder sipe formed in each of the shoulder rib sections extends in the same direction as the first shoulder transverse grooves.

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