Pneumatic tires

Abstract

To provide a pneumatic tire that can prevent a decrease in land stiffness while ensuring snow road surface performance.SOLUTION: In a pneumatic tire, a center land has a plurality of center sipes, all center sipes are connected to a first and second ends of the center land in a tire width direction, respectively, and a first shoulder land has a plurality of first shoulder sipes, all first shoulder sipes are connected to an outer end of the first shoulder land in the tire width direction and are separated from an inner end of the first shoulder land in the tire width direction.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to pneumatic tires. [Background technology]

[0002] Conventionally, for example, a pneumatic tire has a plurality of main grooves extending in the tire circumferential direction, and a plurality of lands defined by the plurality of main grooves and a pair of ground contact edges (for example, Patent Document 1). The lands have a plurality of sipes, and all of the sipes are connected to both ends of the lands in the tire width direction.

[0003] This allows the sipes to easily deform and widen, increasing the traction of the sipe edges on snowy roads. This improves snowy road performance. However, the sipes' tendency to deform easily also reduces the rigidity of the land. This reduces the dry road performance, such as braking performance and steering stability. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-274846 A Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, an object of the present disclosure is to provide a pneumatic tire that can suppress a decrease in rigidity on land while ensuring performance on snowy roads. [Means for solving the problem]

[0006] The pneumatic tire comprises a plurality of main grooves extending in a tire circumferential direction and a plurality of lands defined by the plurality of main grooves and a pair of ground contact edges, the plurality of lands comprising first and second shoulder lands arranged on the outermost sides in a tire width direction and a center land arranged closest to the tire equatorial plane, the center land comprising a plurality of center sipes, all of which are connected to first and second ends of the center land in the tire width direction, respectively, the first shoulder land comprising a plurality of first shoulder sipes, all of which are connected to outer ends of the first shoulder land in the tire width direction and are spaced apart from inner ends of the first shoulder land in the tire width direction. [Brief description of the drawings]

[0007] [Figure 1] Illustrative diagram of the first inclined side [Diagram 2] Illustrative diagram of the second inclined side [Diagram 3] FIG. 1 is a cross-sectional view of a main portion of a pneumatic tire according to an embodiment of the present invention taken along a tire meridian plane. [Figure 4] FIG. 1 is a development view of a main part of a tread surface of a pneumatic tire according to the embodiment; [Diagram 5] An exploded view of the main part of the second shoulder land according to the embodiment [Figure 6] FIG. 1 is an exploded view of a main part of the second mediate land according to the embodiment; [Figure 7] Exploded view of the main part of the center land according to the embodiment [Figure 8] FIG. 1 is a development view of a main part of the first mediate land according to the embodiment; [Figure 9] FIG. 3 is a development view of the main part of the first shoulder land according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, one embodiment of a pneumatic tire will be described with reference to Figures 1 to 9. Note that in each figure, the dimensional ratios in the drawing do not necessarily match the actual dimensional ratios, and the dimensional ratios between the drawings do not necessarily match either.

[0009] The dimensional values, positional relationships, and size relationships described below were measured in a normal unloaded state with a pneumatic tire (hereinafter also simply referred to as "tire") 1 mounted on a normal rim 20 and inflated to normal internal pressure. A normal rim is a rim that is determined for each tire 1 by a standard system that includes the standard on which the tire 1 is based, and is, for example, a standard rim for JATMA and a "Measuring Rim" for TRA and ETRTO.

[0010] In addition, the normal internal pressure is the air pressure set for each tire 1 by each standard in the standard system including the standard on which tire 1 is based, and in the case of JATMA, it is the maximum air pressure, in the case of TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and in the case of ETRTO, it is "INFLATION PRESSURE".

[0011] In each figure, the first direction D1 is the tire width direction D1 which is parallel to the tire rotation axis which is the center of rotation of the tire 1, the second direction D2 is the tire radial direction D2 which is the diameter direction of the tire 1, and the third direction D3 is the tire circumferential direction D3 around the tire rotation axis.

[0012] In the tire width direction D1, the inner side is the side closer to the tire equatorial plane S1, and the outer side is the side farther from the tire equatorial plane S1. In addition, in the tire radial direction D2, the inner side is the side closer to the tire rotation axis, and the outer side is the side farther from the tire rotation axis.

[0013] In the tire width direction D1, the first side D11 is also referred to as the first width direction side D11, and the second side D12 is also referred to as the second width direction side D12. In the tire circumferential direction D3, the first side D31 is also referred to as the first circumferential side D31, and the second side D32 is also referred to as the second circumferential side D32.

[0014] The tire equatorial plane S1 is a plane perpendicular to the tire rotation axis and located at the center in the tire width direction D1 of the tire 1, and the tire meridian plane is a plane that includes the tire rotation axis and is perpendicular to the tire equatorial plane S1. The tire equatorial line is a line where the outer surface of the tire 1 in the tire radial direction D2 (a tread surface 2a described later) and the tire equatorial plane S1 intersect.

[0015] As shown in Fig. 1, the side D4 that approaches the first circumferential side D31 as it approaches the first widthwise side D11 (the side that approaches the second circumferential side D32 as it approaches the second widthwise side D12) is referred to as the first inclined side D4. As shown in Fig. 2, the side D5 that approaches the second circumferential side D32 as it approaches the first widthwise side D11 (the side that approaches the first circumferential side D31 as it approaches the second widthwise side D12) is referred to as the second inclined side D5.

[0016] In addition, "inclined to the same side with respect to the tire circumferential direction D3 (tire width direction D1)" refers to the same inclined side (for example, the first inclined sides D4, D4 and the second inclined sides D5, D5 and the same). In other words, even if the inclination angles with respect to the tire circumferential direction D3 (tire width direction D1) are different, as long as they are the same inclined sides D4, D4 (D5, D5), they are included in "inclined to the same side with respect to the tire circumferential direction D3 (tire width direction D1)".

[0017] Additionally, "inclined on the opposite side with respect to the tire circumferential direction D3 (tire width direction D1)" refers to opposite inclined sides (first inclined side D4 and second inclined side D5). In other words, even if the inclination angle with respect to the tire circumferential direction D3 (tire width direction D1) is the same, if the inclination sides D4 and D5 are opposite, this is included in "inclined on the opposite side with respect to the tire circumferential direction D3 (tire width direction D1)".

[0018] 3, the tire 1 according to this embodiment includes a pair of beads 1a each having a bead core, sidewalls 1b each extending outward in the tire radial direction D2 from each bead 1a, and a tread 2 connected to the outer ends of the pair of sidewalls 1b in the tire radial direction D2, the outer surface (tread surface 2a) of which in the tire radial direction D2 comes into contact with the road surface. In this embodiment, the tire 1 is a pneumatic tire 1 in which air is put, and is mounted on a rim 20.

[0019] The tire 1 also includes a carcass 1c that is bridged between a pair of bead cores, and an inner liner 1d that is disposed inside the carcass 1c and has an excellent function of preventing gas permeation in order to maintain air pressure. The carcass 1c and the inner liner 1d are disposed along the inner circumference of the tire, spanning the beads 1a, the sidewalls 1b, and the tread 2.

[0020] The tire 1 has a structure that is asymmetric with respect to the tire equatorial plane S1. In this embodiment, the tire 1 is a tire for which the mounting direction on a vehicle is specified, and which side of the tire 1 faces the vehicle when mounted on the rim 20 is specified. The tread pattern formed on the tread surface 2a of the tread 2 has a shape that is asymmetric with respect to the tire equatorial plane S1.

[0021] The mounting orientation on the vehicle may be indicated, for example, on the sidewall 1b. Specifically, the sidewall 1b may include a sidewall rubber 1e arranged on the outer side of the carcass 1c in the tire width direction D1 to form the tire outer surface, and the sidewall rubber 1e may have an indication portion (not shown) on the surface thereof that indicates the mounting orientation on the vehicle.

[0022] For example, one sidewall 1b that is disposed on the inside (hereinafter also referred to as the "vehicle inner side") when mounted on a vehicle is marked with a label indicating that it is the vehicle inner side (for example, "INSIDE" or the like). Also, for example, the other sidewall 1b that is disposed on the outside (hereinafter also referred to as the "vehicle outer side") when mounted on a vehicle is marked with a label indicating that it is the vehicle outer side (for example, "OUTSIDE" or the like). Although not particularly limited, for example, as in this embodiment, the first width direction side D11 may be the vehicle inner side D11 and the second width direction side D12 may be the vehicle outer side D12.

[0023] The tread 2 includes a tread rubber 2b having a tread surface 2a that comes into contact with the road surface, and a belt 2c disposed between the tread rubber 2b and the carcass 1c. The tread surface 2a has a contact surface that actually comes into contact with the road surface, and the outer ends of the contact surface in the tire width direction D1 are called contact ends 2d, 2e. The contact surface refers to the tread surface 2a that comes into contact with the road surface when the tire 1 is mounted on a standard rim 20, inflated to a standard internal pressure, placed vertically on a flat road surface, and a standard load is applied.

[0024] The normal load is the load determined for each tire 1 by each standard in the standard system including the standard on which tire 1 is based. For JATMA, it is the maximum load capacity, for TRA, it is the maximum value shown in the table above, and for ETRTO, it is the "LOAD CAPACITY." However, if tire 1 is for passenger cars, it is 85% of the corresponding load at an internal pressure of 180 kPa.

[0025] 3 and 4, the tread rubber 2b includes a plurality of main grooves 3, 4, 5, 6 extending in the tire circumferential direction D3, and a plurality of lands 7, 8, 9, 10, 11 defined by the plurality of main grooves 3, 4, 5, 6 and a pair of ground contact edges 2d, 2e. Although not particularly limited, for example, as in this embodiment, the number of the main grooves 3, 4, 5, 6 may be four, and the number of the lands 7, 8, 9, 10, 11 may be five.

[0026] The main grooves 3, 4, 5, 6 extend continuously in the tire circumferential direction D3. The main grooves 3, 4, 5, 6 may have a portion that is shallower, a so-called tread wear indicator (not shown), which becomes exposed as the grooves wear, to indicate the degree of wear. For example, the main grooves 3, 4, 5, 6 may have a groove width that is 3% or more of the distance between the ground contact ends 2d, 2e (the dimension in the tire width direction D1). For example, the main grooves 3, 4, 5, 6 may have a groove width that is 5 mm or more.

[0027] A pair of main grooves 3, 4 arranged on the outermost sides in the tire width direction D1 are referred to as shoulder main grooves 3, 4. Of the shoulder main grooves 3, 4, the main groove 3 arranged on the first width direction side (vehicle inner side) D11 is referred to as the first shoulder main groove 3, and the main groove 4 arranged on the second width direction side (vehicle outer side) D12 is referred to as the second shoulder main groove 4.

[0028] The main grooves 5, 6 disposed between the pair of shoulder main grooves 3, 4 are referred to as center main grooves 5, 6. Of the center main grooves 5, 6, the main groove 5 disposed on the first width direction side (vehicle inner side) D11 is referred to as the first center main groove 5, and the main groove 6 disposed on the second width direction side (vehicle outer side) D12 is referred to as the second center main groove 6.

[0029] The lands 7, 8 defined by the shoulder main grooves 3, 4 and the ground contact edges 2d, 2e are called shoulder lands 7, 8, and the lands 9, 10, 11 defined by a pair of adjacent main grooves 3, 4, 5, 6 are called middle lands 9, 10, 11. The middle lands 9, 10 defined by the shoulder main grooves 3, 4 and the center main grooves 5, 6 are also called mediate lands 9, 10, and the middle land 11 defined by a pair of center main grooves 5, 6 is also called center land 11.

[0030] Of the shoulder lands 7, 8, the land 7 arranged on the first width direction side (vehicle inner side) D11 is referred to as the first shoulder land 7, and the land 8 arranged on the second width direction side (vehicle outer side) D12 is referred to as the second shoulder land 8. Also, of the intermediate lands 9, 10, the land 9 arranged on the first width direction side (vehicle inner side) D11 is referred to as the first intermediate land 9, and the land 10 arranged on the second width direction side (vehicle outer side) D12 is referred to as the second intermediate land 10.

[0031] Although not particularly limited, for example, as in this embodiment, the main grooves 3, 4, 5, 6 may include straight main grooves 4, 6 and zigzag main grooves 3, 5. The straight main grooves 4, 6 are main grooves 4, 6 whose edges on the tread surface 2a are parallel to the tire circumferential direction D3, and the zigzag main grooves 3, 5 are main grooves 3, 5 whose edges on the tread surface 2a are inclined with respect to the tire circumferential direction D3.

[0032] The lands 7, 8, 9, 10, 11 each include a plurality of sub-grooves 12, 13, ..., 18, 19. Of the sub-grooves 12, 13, ..., 18, 19, the sub-groove 12 extending along the tire circumferential direction D3 is referred to as the circumferential groove 12, and of the sub-grooves 12, 13, ..., 18, 19, the sub-grooves 13, 14, ..., 18, 19 extending along the tire width direction D1 are referred to as the lateral grooves 13, 14, ..., 18, 19.

[0033] Among the lateral grooves 13, 14, ..., 18, 19, the lateral groove 13 having a groove width of 1.6 mm or more on the tread surface 2a is called a slit 13. Also, among the lateral grooves 13, 14, ..., 18, 19, the lateral grooves 14, 15, ..., 18, 19 having a groove width of less than 1.6 mm on the tread surface 2a are called sipes 14, 15, ..., 18, 19.

[0034] The inclination angle of the circumferential groove 12 with respect to the tire circumferential direction D3 is preferably less than 45°, for example, 30° or less. The inclination angle of the width grooves 13, 14, ..., 18, 19 with respect to the tire width direction D1 is preferably 45° or less, for example, 30° or less.

[0035] Although not particularly limited, for example, as in this embodiment, all the slits 13 may extend over the entire length of the lands 7, 8, 9, 10, 11 in the tire width direction D1. That is, both ends of all the slits 13 may be connected to the main grooves 3, 4, 5, 6 or the ground contact edges 2d, 2e, respectively. As a result, the lands 7, 8, 9, 10, 11 have a plurality of blocks 7a, 8a, 9a, 10a, 11a partitioned by the slits 13 so as to be aligned in the tire circumferential direction D3.

[0036] Although not particularly limited, for example, as in this embodiment, the numbers of blocks 7a, 8a, 9a, 10a, and 11a of each land 7, 8, 9, 10, and 11 may be the same, and the numbers of slits 13 of each land 7, 8, 9, 10, and 11 may be the same. Furthermore, although not particularly limited, for example, as in this embodiment, the groove width of the slit 13 may be constant (including not only the same but also approximately the same with a difference of ±5%) over the entire length.

[0037] Here, the configurations of the sipes 14, 16, 17 of the lands 7, 9 on the vehicle inner side (first width direction side) D11 and the sipes 15, 18 of the lands 8, 10 on the vehicle outer side (second width direction side) D12 will be described with reference to Figs. 5 to 9.

[0038] 5 to 9, for example, the sipes 14, 15, ..., 18, 19 include straight portions 14a, 15a, ..., 18a, 19a that extend straight and zigzag portions 14b, 15b, ..., 18b, 19b that extend zigzag. Note that the sipes 14, 15, ..., 18, 19 may be composed of only the straight portions 14a, 15a, ..., 18a, 19a, or may be composed of only the zigzag portions 14b, 15b, ..., 18b, 19b.

[0039] First, the number of sipes 14 on the first shoulder land 7 is greater than the number of sipes 15 on the second shoulder land 8. Also, the total length of the sipes 14 on the first shoulder land 7 is greater than the total length of the sipes 15 on the second shoulder land 8.

[0040] Also, for example, as in this embodiment, the number of sipes 16, 17 of the first intermediate land 9 may be greater than the number of sipes 18 of the second intermediate land 10. And, for example, the total length of the sipes 16, 17 of the first intermediate land 9 may be greater than the total length of the sipes 18 of the second intermediate land 10.

[0041] In this way, in the lands 7, 9 that are entirely disposed on the first width direction side (vehicle inner side) D11 from the tire equatorial plane S1, the length of the sipes 14, 16, 17 is increased, so that the traction by the edges of the sipes 14, 16, 17 of the lands 7, 9 on the first width direction side (vehicle inner side) D11 can be increased, thereby improving the snowy road surface performance.

[0042] Moreover, by preventing the length of the sipes 15, 18 from becoming too long in the lands 8, 10 that are entirely disposed on the second width direction side (vehicle outer side) D12 of the tire equatorial plane S1, it is possible to prevent the rigidity of the lands 8, 10 on the second width direction side (vehicle outer side) D12 from decreasing, thereby improving the dry road performance (especially the steering stability during cornering).

[0043] Therefore, it is possible to achieve both snowy road performance by exerting traction and dry road performance by ensuring rigidity. As a result, although not particularly limited, the tire 1 according to the present embodiment can be used as an all-season tire (a tire suitable for dry roads and snowy roads). Note that the length of the sipes 14, 15, ..., 18, 19 (the same applies to the lengths of the respective parts 14a, 14b, 15a, 15b, ..., 18a, 18b, 19a, 19b described later) refers to the length of the groove width center of the sipes 14, 15, ..., 18, 19.

[0044] Also, for example, as in this embodiment, in the sipes 14, 16, 17 of the lands 7, 9 on the first width direction side (vehicle inner side) D11, the length of the zigzag portions 14b, 16b, 17b may be longer than the length of the straight portions 14a, 16a, 17a. This allows the length of the sipes 14, 16, 17 to be longer, thereby increasing the traction by the edges of the sipes 14, 16, 17.

[0045] Also, for example, as in this embodiment, in the sipes 15, 18 of the lands 8, 10 on the second width direction side (vehicle outer side) D12, the length of the straight portions 15a, 18a may be longer than the length of the zigzag portions 15b, 18b. This makes it possible to prevent the length of the sipes 15, 18 from becoming too long, and therefore to prevent the rigidity of the lands 8, 10 from decreasing.

[0046] In this manner, for example, as in the present embodiment, the zigzag ratio of the sipes 14, 16, 17 of the lands 7, 9 on the first width direction side (vehicle inner side) D11 may be greater than the zigzag ratio of the sipes 15, 18 of the lands 8, 10 on the second width direction side (vehicle outer side) D12. The zigzag ratio refers to the ratio of the length of the zigzag portions 14b, 15b, ..., 18b, 19b to the length of the sipes 14, 15, ..., 18, 19.

[0047] For example, as in this embodiment, the zigzag ratio of the sipe 14 of the first shoulder land 7 may be greater than the zigzag ratio of the sipe 15 of the second shoulder land 8. Also, for example, as in this embodiment, the zigzag ratio of the sipes 16, 17 of the first intermediate land 9 may be greater than the zigzag ratio of the sipe 18 of the second intermediate land 10.

[0048] For example, as in this embodiment, the length of the zigzag portion 19b of the sipe 19 of the center land 11 may be longer than the length of the straight portion 19a. Also, for example, as in this embodiment, the zigzag ratio of the sipe 19 of the center land 11 may be greater than the zigzag ratio of the sipe 15 of the second shoulder land 8, and may be greater than the zigzag ratio of the sipe 18 of the second intermediate land 10.

[0049] Next, the configuration of each of the lands 7, 8, 9, 10, and 11 will be described with reference to FIGS.

[0050] First, the configuration of the second shoulder land 8 will be described with reference to FIG.

[0051] As shown in Fig. 5, in the second shoulder land 8, the length of the sipe (also called "second shoulder sipe") 15 can be prevented from becoming too long. This ensures rigidity, but the traction by the edge of the sipe 15 tends to be small.

[0052] Therefore, the first ends 15c (outer ends in the tire width direction D1) of all the sipes 15 are connected to the outer ends 8b in the tire width direction D1 of the second shoulder land 8, and the second ends 15d (inner ends in the tire width direction D1) of all the sipes 15 are connected to the inner ends 8c in the tire width direction D1 of the second shoulder land 8. That is, the first ends 15c of the sipes 15 are connected to the second ground-contact edge 2e, and the second ends 15d of the sipes 15 are connected to the second shoulder main groove 4.

[0053] This allows the sipes 15 to easily deform and widen, increasing the traction on snowy road surfaces by the edges of the sipes 15. Therefore, in the second shoulder land 8, for example, it is possible to achieve both dry road performance by ensuring rigidity and snowy road performance by providing traction.

[0054] For example, as in this embodiment, the straight portion 15a may be arranged in pairs on both sides of the sipe 15 in the tire width direction D1, and the zigzag portion 15b may be arranged between the pair of straight portions 15a, 15a. Also, for example, as in this embodiment, the slits 13 of the second shoulder land 8 and the sipe 15 may be inclined to the same side (second inclined side) D5 with respect to the tire width direction D1.

[0055] Next, the configuration of the second mediate land 10 will be described with reference to FIG.

[0056] As shown in Fig. 6, in the second intermediate land 10, the length of the sipe (also called the "third intermediate sipe") 18 can be prevented from becoming too long. This ensures rigidity, but the traction by the edge of the sipe 15 tends to be small.

[0057] Therefore, for example, as in this embodiment, the first ends 18c (outer ends in the tire width direction D1) of all the sipes 18 may be connected to the outer ends 10b in the tire width direction D1 of the second intermediate land 10, and the second ends 18d (inner ends in the tire width direction D1) of all the sipes 18 may be connected to the inner ends 10c in the tire width direction D1 of the second intermediate land 10. That is, the first ends 18c of the sipes 18 may be connected to the second shoulder main groove 4, and the second ends 18d of the sipes 18 may be connected to the second center main groove 6.

[0058] This allows the sipes 18 to easily deform so as to widen, thereby increasing the traction on snowy road surfaces due to the edges of the sipes 18. Therefore, in the second intermediate land 10, for example, it is possible to achieve both dry road performance by ensuring rigidity and snowy road performance by exerting traction.

[0059] For example, as in this embodiment, the straight portion 18a may be arranged in pairs on both sides of the sipe 18 in the tire width direction D1, and the zigzag portion 18b may be arranged between the pair of straight portions 18a, 18a. Also, for example, as in this embodiment, the slits 13 of the second intermediate land 10 and the sipe 18 may be inclined to the same side (second inclined side) D5 with respect to the tire width direction D1.

[0060] Next, the configuration of the first shoulder land 7 will be described with reference to FIG.

[0061] 9, in the first shoulder land 7, the length of the sipes (also called "first shoulder sipes") 14 is long, so that the traction by the edges of the sipes 14 can be increased, but the rigidity is likely to decrease. Therefore, the second ends 14d (inner ends in the tire width direction D1) of all the sipes 14 are separated from the inner ends 7c of the first shoulder land 7 in the tire width direction D1. That is, the second ends 14d of the sipes 14 are separated from the first shoulder main groove 3.

[0062] This makes it possible to prevent the rigidity of the first shoulder land 7 from decreasing, thereby improving the dry road performance (especially the braking performance). Therefore, in the first shoulder land 7, it is possible to achieve both the snow road performance by exerting the traction and the dry road performance by ensuring the rigidity.

[0063] When the vehicle is traveling, the position of the actual ground contact edge changes in the tire width direction D1. For example, when the load is heavy, the actual ground contact edge is located outside the first and second ground contact edges 2d, 2e in the tire width direction D1, and when the load is light, the actual ground contact edge is located inside the first and second ground contact edges 2d, 2e in the tire width direction D1.

[0064] In contrast, the sipes 14 are spaced apart from the inner end 7c of the first shoulder land 7, not from the outer end 7b of the first shoulder land 7. This ensures that the second ends 14d of the sipes 14 are spaced apart from the inner end 7c of the first shoulder land 7, even if the position of the actual ground contact edge changes in the tire width direction D1. This ensures that the rigidity of the first shoulder land 7 is prevented from decreasing.

[0065] The first ends 14c (outer ends in the tire width direction D1) of all the sipes 14 are connected to the outer ends 7b in the tire width direction D1 of the first shoulder land 7. That is, the first ends 14c of all the sipes 14 are connected to the first ground-contact ends 2d.

[0066] This ensures that the sipes 14 can easily spread, thereby preventing a decrease in traction due to the edges of the sipes 14. The length of the sipes 14 in the tire width direction D1 is preferably, for example, 67% (= 2 / 3) or more of the length (for example, the maximum length) of the blocks 7a in the tire width direction D1, and more preferably, for example, 75% (= 3 / 4) or more.

[0067] Also, for example, as in this embodiment, the straight portion 14a may be disposed on the inside of the sipe 14 in the tire width direction D1, and the zigzag portion 14b may be disposed on the outside of the sipe 14 in the tire width direction D1. Also, for example, as in this embodiment, the slit 13 of the first shoulder land 7 and the sipe 14 may be inclined to the same side (second inclined side) D5 with respect to the tire width direction D1.

[0068] Next, the configuration of the center land 11 will be described with reference to FIG.

[0069] For example, when a vehicle travels straight, the contact length (length in the tire circumferential direction D3) of the inner region in the tire width direction D1, particularly the center land 11, becomes long. As a result, many sipes (also called "center sipes") 19 of the center land 11 come into contact with the ground.

[0070] 7, in the center land 11, the first ends 19c of all the sipes 19 are connected to the first ends 11b of the center land 11 in the tire width direction D1, and the second ends 19d of all the sipes 19 are connected to the second ends 11c of the center land 11 in the tire width direction D1. That is, the first ends 19c of the sipes 19 are connected to the first center main groove 5, and the second ends 19d of the sipes 19 are connected to the second center main groove 6.

[0071] As a result, the sipes 19 on the center land 11, which has a long contact length, can easily deform to widen, effectively increasing the traction on snowy road surfaces by the edges of the sipes 19. Therefore, in the center land 11, for example, the snowy road performance due to the exertion of traction can be effectively improved.

[0072] For example, as in this embodiment, the straight portion 19a may be arranged in pairs on both sides of the sipe 19 in the tire width direction D1, and the zigzag portion 19b may be arranged between the pair of straight portions 19a, 19a. Also, for example, as in this embodiment, the slit 13 of the center land 11 and the sipe 19 may be inclined to the same side (second inclined side) D5 with respect to the tire width direction D1.

[0073] Next, the configuration of the first mediate land 9 will be described with reference to FIG.

[0074] 8, in the first intermediate land 9, the first ends 16c, 17c of all the sipes 16, 17 are connected to the side ends 9b, 9c of the first intermediate land 9 in the tire width direction D1. That is, the first ends 16c, 17c of all the sipes 16, 17 are connected to the main grooves 3, 5. This ensures that the sipes 16, 17 can easily expand.

[0075] On the other hand, the second ends 16d, 17d of all the sipes 16, 17 are spaced apart from the side ends 9c, 9b of the first intermediate land 9 in the tire width direction D1. That is, the second ends 16d, 17d of all the sipes 16, 17 are spaced apart from the main grooves 5, 3. This makes it possible to suppress a decrease in the rigidity of the first intermediate land 9. In this way, in the first intermediate land 9, for example, it is possible to achieve both snowy road performance by exerting traction and dry road performance by ensuring rigidity.

[0076] Moreover, an outer end 9b of the first intermediate land 9 is connected to a first sipe (also referred to as a "first intermediate sipe") 16, but is separated from a second sipe (also referred to as a "second intermediate sipe") 17, and an inner end 9c of the first intermediate land 9 is connected to the second sipe 17, but is separated from the first sipe 16. This makes it possible to suppress the occurrence of a stiffness difference in the first intermediate land 9 in the tire width direction D1.

[0077] In addition, while the first end 19c and the second end 19d of the center sipe 19 are connected to the side ends 11b, 11c of the center land 11, only the first end 14c of the first shoulder sipe 14 is connected to the side end 7b of the first shoulder land 7, so the rigidity of the center land 11 tends to be lower than the rigidity of the first shoulder land 7. In contrast, the number of second sipes 17 is smaller than the number of first sipes 16.

[0078] This makes it possible to suppress a decrease in the rigidity of the inner region in the tire width direction D1 of the first intermediate land 9, i.e., the region on the center land 11 side. Therefore, for example, it is possible to improve the balance of the rigidity of the center land 11, the first intermediate land 9, and the first shoulder land 7. Note that the length of the sipes 16, 17 in the tire width direction D1 is preferably, for example, 67% (= 2 / 3) or more of the length (for example, the maximum length) of the block 9a in the tire width direction D1, and more preferably, for example, 75% (= 3 / 4) or more.

[0079] Also, for example, as in this embodiment, in the first sipe 16, the straight portion 16a may be arranged on the outer side of the sipe 16 in the tire width direction D1, and the zigzag portion 16b may be arranged on the inner side of the sipe 16 in the tire width direction D1. Also, for example, as in this embodiment, in the second sipe 17, the straight portion 17a may be arranged on the inner side of the sipe 17 in the tire width direction D1, and the zigzag portion 17b may be arranged on the outer side of the sipe 17 in the tire width direction D1.

[0080] That is, in the sipes 16, 17 of the first intermediate land 9, the straight portions 16a, 17a are connected to the side ends 9b, 9c of the first intermediate land 9, and the zigzag portions 16b, 17b are spaced apart from the side ends 9c, 9b of the first intermediate land 9. Also, for example, as in this embodiment, the slits 13 of the first intermediate land 9 and the sipes 16, 17 may be inclined to the same side (second inclined side) D5 with respect to the tire width direction D1.

[0081] 5 to 9, for example, as in this embodiment, the slits 13 of each land 7, 8, 9, 10, 11 may be inclined to the same side (second inclined side) D5 with respect to the tire width direction D1. Also, for example, as in this embodiment, the sipes 14, 15, ..., 18, 19 of each land 7, 8, 9, 10, 11 may be inclined to the same side (second inclined side) D5 with respect to the tire width direction D1.

[0082] As described above, in the present embodiment, the pneumatic tire 1 includes a plurality of main grooves 3, 4, 5, 6 extending in the tire circumferential direction D3, and a plurality of lands 7, 8, 9, 10, 11 defined by the plurality of main grooves 3, 4, 5, 6 and a pair of ground contact edges 2d, 2e. The plurality of lands 7, 8, 9, 10, 11 include first and second shoulder lands 7, 8 disposed on the outermost sides in the tire width direction D1, and a center land 11 disposed closest to the tire equatorial plane S1. The center land 11 includes a plurality of It is preferable that the first shoulder land 7 has a plurality of first shoulder sipes 14, and all of the first shoulder sipes 14 are connected to the outer ends 7b of the first shoulder land 7 in the tire width direction D1 and are spaced apart from the inner ends 7c of the first shoulder land 7 in the tire width direction D1.

[0083] With this configuration, when the vehicle travels straight, the contact length of the inner region in the tire width direction D1 becomes longer, but all of the center sipes 19 are connected to the first end 11b and the second end 11c of the center land 11. This makes it easier for the numerous center sipes 19, which come into contact with the ground, to deform so as to widen, thereby increasing traction by the edges of the center sipes 19 on snowy road surfaces.

[0084] In addition, since the first shoulder sipes 14 are connected to the outer end 7b of the first shoulder land 7, it is possible to ensure that the first shoulder sipes 14 can easily expand. Moreover, since the first shoulder sipes 14 are separated from the inner end 7c of the first shoulder land 7, it is possible to suppress a decrease in the rigidity of the first shoulder land 7.

[0085] Furthermore, since the first shoulder sipes 14 are located away from the inner end 7c of the first shoulder land 7, rather than the outer end 7b, the first shoulder sipes 14 can be located away from the inner end 7c of the first shoulder land 7 even if the actual ground contact edge position changes in the tire width direction D1. This reliably prevents the rigidity of the first shoulder land 7 from decreasing. Therefore, it is possible to prevent the rigidity of the land 7 from decreasing while ensuring snow road performance.

[0086] Furthermore, as in this embodiment, in the pneumatic tire 1, the second shoulder land 8 is preferably configured so that the sum of the lengths of the plurality of first shoulder sipes 14 is greater than the sum of the lengths of the plurality of second shoulder sipes 15, and all of the second shoulder sipes 15 are connected to the outer end 8b and the inner end 8c of the second shoulder land 8 in the tire width direction D1, respectively.

[0087] According to this configuration, the edge length of the sipes 14 of the first shoulder land 7 can be increased, thereby increasing the traction provided by the edges of the sipes 14 of the first shoulder land 7. On the other hand, since the first shoulder sipes 14 are located away from the inner end 7c of the first shoulder land 7, a decrease in the rigidity of the first shoulder land 7 can be suppressed.

[0088] Also, since the length of the sipes 15 of the second shoulder land 8 can be prevented from becoming too long, a decrease in the rigidity of the second shoulder land 8 can be prevented. Meanwhile, the second shoulder sipes 15 are connected to both the outer end 8b and the inner end 8c of the second shoulder land 8. This allows the second shoulder sipes 15 to easily deform so as to widen, thereby increasing the traction provided by the edges of the second shoulder sipes 15 on a snowy road surface.

[0089] Furthermore, as in this embodiment, in the pneumatic tire 1, the multiple lands 7, 8, 9, 10, 11 further include an intermediate land (in this embodiment, the first intermediate land) 9 arranged between the first shoulder land 7 and the center land 11, and the intermediate land 9 has multiple intermediate sipes 16, 17, and first ends 16c, 17c of all the intermediate sipes 16, 17 are connected to the side ends 9b, 9c of the intermediate land 9 in the tire width direction D1, and second ends 16d, 17d of all the intermediate sipes 16, 17 are separated from the side ends 9b, 9c of the intermediate land 9 in the tire width direction D1.

[0090] According to this configuration, the first ends 16c, 17c of the intermediate sipes 16, 17 are connected to the side ends 9b, 9c of the intermediate land 9, so that the ease of spreading of the intermediate sipes 16, 17 can be ensured. On the other hand, the second ends 16d, 17d of the intermediate sipes 16, 17 are separated from the side ends 9c, 9b of the intermediate land 9, so that the rigidity of the intermediate land 9 can be prevented from decreasing.

[0091] In addition, as in this embodiment, in the pneumatic tire 1, the multiple intermediate sipes 16, 17 include multiple first intermediate sipes 16 and multiple second intermediate sipes 17, and the first ends 16c of all the first intermediate sipes 16 are connected to the outer ends 9b of the mediate land (in this embodiment, the first mediate land) 9 in the tire width direction D1, the second ends 16d of all the first mediate sipes 16 are separated from the inner ends 9c of the mediate land 9 in the tire width direction D1, the first ends 17c of all the second mediate sipes 17 are connected to the inner ends 9c of the mediate land 9 in the tire width direction D1, and the second ends 17d of all the second mediate sipes 17 are separated from the outer ends 9b of the mediate land 9 in the tire width direction D1.

[0092] According to this configuration, the outer end 9b of the intermediate land 9 is connected to the first intermediate sipe 16 while being separated from the second intermediate sipe 17, and the inner end 9c of the intermediate land 9 is connected to the second intermediate sipe 17 while being separated from the first intermediate sipe 16. This makes it possible to suppress the occurrence of a stiffness difference in the intermediate land 9 in the tire width direction D1.

[0093] In addition, in the pneumatic tire 1 as in this embodiment, it is preferable that the number of the second intermediate sipes 17 is smaller than the number of the first intermediate sipes 16.

[0094] According to this configuration, while the rigidity of the center land 11 tends to be lower than the rigidity of the first shoulder land 7, the number of intermediate sipes 17 connected to the inner end 9c of the intermediate land 9 is smaller than the number of intermediate sipes 16 connected to the outer end 9b of the intermediate land 9. This makes it possible to suppress a decrease in the rigidity of the inner region of the intermediate land 9 in the tire width direction D1, i.e., the region on the center land 11 side.

[0095] The pneumatic tire 1 is not limited to the configuration of the above-described embodiment, and is not limited to the above-described action and effect. Of course, various modifications can be made to the pneumatic tire 1 without departing from the gist of the present invention. For example, it is of course possible to arbitrarily select one or more of the configurations, methods, etc. of the various modified examples described below and adopt them in the configurations, methods, etc. of the above-described embodiment.

[0096] (1) In the pneumatic tire 1 according to the above embodiment, the total length of the sipes 14 in the first shoulder land 7 is greater than the total length of the sipes 15 in the second shoulder land 8. However, the pneumatic tire 1 is not limited to this configuration.

[0097] For example, the total length of the sipes 14 on the first shoulder land 7 may be smaller than the total length of the sipes 15 on the second shoulder land 8. Also, for example, the total length of the sipes 14 on the first shoulder land 7 may be the same as the total length of the sipes 15 on the second shoulder land 8.

[0098] (2) In the pneumatic tire 1 according to the above embodiment, all of the sipes 15 of the second shoulder land 8 are connected to the side ends 8b, 8c of the second shoulder land 8. However, the pneumatic tire 1 is not limited to this configuration. For example, at least one of the sipes 15 of the second shoulder land 8 may be separated from at least one of the side ends 8b, 8c of the second shoulder land 8.

[0099] (3) In addition, in the pneumatic tire 1 according to the above embodiment, the first ends 16c, 17c of all the sipes 16, 17 of the first intermediate land 9 are connected to the side ends 9b, 9c of the intermediate land 9, and the second ends 16d, 17d of all the sipes 16, 17 of the first intermediate land 9 are separated from the side ends 9c, 9b of the intermediate land 9. However, the pneumatic tire 1 is not limited to such a configuration.

[0100] For example, at least one sipe 16, 17 of the first intermediate land 9 may be connected to the outer end 9b and the inner end 9c of the first intermediate land 9. Also, for example, at least one sipe 16, 17 of the first intermediate land 9 may be separated from both the outer ends 9b and the inner ends 9c of the first intermediate land 9.

[0101] (4) In the pneumatic tire 1 according to the above embodiment, the outer end 9b of the first intermediate land 9 is connected to a sipe 16 that is a part of the first intermediate land 9, and the inner end 9c of the first intermediate land 9 is connected to a sipe 17 that is a part of the first intermediate land 9. However, the pneumatic tire 1 is not limited to such a configuration.

[0102] For example, the outer end 9b of the first mediate land 9 may be connected to all the sipes 16, 17 of the first mediate land 9, and the inner end 9c of the first mediate land 9 may be separated from all the sipes 16, 17 of the first mediate land 9. Also, for example, the inner end 9c of the first mediate land 9 may be connected to all the sipes 16, 17 of the first mediate land 9, and the outer end 9b of the first mediate land 9 may be separated from all the sipes 16, 17 of the first mediate land 9.

[0103] (5) In addition, in the pneumatic tire 1 according to the above embodiment, the number of the second sipes 17 in the first intermediate land 9 is smaller than the number of the first sipes 16 in the first intermediate land 9. However, the pneumatic tire 1 is not limited to such a configuration.

[0104] For example, the number of the second sipes 17 of the first intermediate land 9 may be greater than the number of the first sipes 16 of the first intermediate land 9. Also, for example, the number of the second sipes 17 of the first intermediate land 9 may be the same as the number of the first sipes 16 of the first intermediate land 9.

[0105] (6) In the pneumatic tire 1 according to the above embodiment, the number of land 11 intersecting with the tire equatorial plane S1 is one, and the center land 11 disposed closest to the tire equatorial plane S1 is the land. However, the pneumatic tire 1 is not limited to such a configuration.

[0106] For example, the number of lands intersecting the tire equatorial plane S1 may be zero, or may be two. In these configurations, two center lands 11 are provided that are located closest to the tire equatorial plane S1, but it is sufficient that the first center land 11 and the first shoulder land 7, which are located on the first width direction side D11, among the first and second center lands 11 and the first and second shoulder lands 7, 8, have a predetermined configuration.

[0107] The specified configuration means that all sipes 19 of the first center land 11 are connected to the first end 11b and the second end 11c of the first center land 11, respectively, and all sipes 14 of the first shoulder land 7 are connected to the outer end 7b of the first shoulder land 7 and are spaced apart from the inner end 7c of the first shoulder land 7.

[0108] (7) Furthermore, the pneumatic tire 1 according to the above embodiment is configured as a tire for which the mounting orientation on a vehicle is specified. However, the pneumatic tire 1 is not limited to such a configuration. For example, the pneumatic tire 1 may be configured as a tire for which the mounting orientation on a vehicle is not specified. Specifically, the tread pattern may be a tread pattern that is point-symmetric with respect to an arbitrary point on the tire equator line, or a tread pattern that is line-symmetric with respect to the tire equator line. [Explanation of symbols]

[0109] 1...pneumatic tire, 1a...bead, 1b...sidewall, 1c...carcass, 1d...inner liner, 1e...sidewall rubber, 2...tread, 2a...tread surface, 2b...tread rubber, 2c...belt, 2d...first ground contact edge, 2e...second ground contact edge, 3...first shoulder main groove, 4...second shoulder main groove, 5...first center main groove, 6...second center main groove, 7...first shoulder land, 7a,8a,9a,10a,11a...block, 7b,8b,9b,10b...outer end, 7c,8c,9c,10c...inner end, 8...second shoulder land, 9...first mediate land, 10...second mediate land, 11...center land, 11b...first end, 11c...second end, 12...circumferential groove, 13...slit, 14...first shoulder sag 14a, 15a, 16a, 17a, 18a, 19a...straight portion, 14b, 15b, 16b, 17b, 18b, 19b...zigzag portion, 14c, 15c, 16c, 17c, 18c, 19c...first end, 14d, 15d, 16d, 17d, 18d, 19d...second end, 15...second shoulder sipe, 16...first intermediate sipe, 17...second Mediate sipe, 18...third mediate sipe, 19...center sipe, 20...rim, D1...tire width direction, D2...tire radial direction, D3...tire circumferential direction, D4...first inclined side, D5...second inclined side, D11...first width direction side (vehicle inner side), D12...second width direction side (vehicle outer side), D31...first circumferential side, D32...second circumferential side, S1...tire equatorial plane

Claims

1. The tire has a plurality of main grooves extending in a circumferential direction of the tire, and a plurality of lands defined by the plurality of main grooves and a pair of ground contact edges, The plurality of lands include first and second shoulder lands arranged on the outermost sides in the tire width direction, and a center land arranged closest to a tire equatorial plane, The center land has a plurality of center sipes, All of the center sipes are connected to a first end and a second end of the center land in the tire width direction, The first shoulder land includes a plurality of first shoulder sipes, All of the first shoulder sipes are connected to outer ends of the first shoulder land in the tire width direction and are spaced apart from inner ends of the first shoulder land in the tire width direction. The second shoulder land includes a plurality of second shoulder sipes, A total length of the first shoulder sipes is greater than a total length of the second shoulder sipes, all of the second shoulder sipes are connected to outer ends and inner ends of the second shoulder land in the tire width direction, respectively.

2. A tire comprising a plurality of main grooves extending in a circumferential direction, and a plurality of lands defined by the plurality of main grooves and a pair of ground contact edges, The plurality of lands include first and second shoulder lands arranged on the outermost sides in the tire width direction, and a center land arranged closest to a tire equatorial plane, The center land has a plurality of center sipes, All of the center sipes are connected to a first end and a second end of the center land in the tire width direction, The first shoulder land includes a plurality of first shoulder sipes, All of the first shoulder sipes are connected to outer ends of the first shoulder land in the tire width direction and are spaced apart from inner ends of the first shoulder land in the tire width direction. The plurality of lands further includes a mediate land disposed between the first shoulder land and the center land, The mediate land includes a plurality of mediate sipes, A first end of each of the mediate sipes is connected to a side end of the mediate land in the tire width direction, and a second end of each of the mediate sipes is separated from the side end of the mediate land in the tire width direction, The plurality of mediate sipes includes a plurality of first mediate sipes and a plurality of second mediate sipes, First ends of all the first intermediate sipes are connected to outer ends of the mediate lands in the tire width direction, and second ends of all the first intermediate sipes are spaced apart from inner ends of the mediate lands in the tire width direction, First ends of all the second intermediate sipes are connected to inner ends of the intermediate lands in the tire width direction, and second ends of all the second intermediate sipes are separated from outer ends of the intermediate lands in the tire width direction, The number of the second intermediate sipes is less than the number of the first intermediate sipes.

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