JP6788385B2 - tire - Google Patents

Description

The present invention relates to a tire in which a 3D sipe is formed on a tire tread side of a tread land portion, and more particularly to a tire having excellent on-ice performance.

Conventionally, as a tread pattern for a studless tire, in order to improve on-ice performance, a lug groove extending in a direction intersecting the circumferential groove is provided, and a tire width direction is provided on the surface of a block partitioned by the circumferential groove and the lug groove. Many tires have a sipe that extends to the tire.
However, in the above configuration, although the performance on ice is improved, the block is subdivided by sipes, so that the block rigidity is lowered, and as a result, the ground contact property may be lowered.
Therefore, a method has been proposed in which the sipe is a 3D sipe whose shape is changed not only on the tire tread side but also in the tire radial direction to improve the sipe contact force and suppress the decrease in block rigidity (for example). , Patent Document 1).

Japanese Unexamined Patent Publication No. 2008-49971

By the way, since the 3D sipe has a shape that bends in the depth direction, the pull-out resistance when pulling out the vulcanized tire from the mold is large, and as a result, a large pull-out force is required. When the pull-out force becomes large, there arises a problem that shape defects are likely to occur, such as the bent portion of the sipe expanding.
The present invention has been made in view of the conventional problems, and provides a tire provided with a 3D sipe that can secure a sipe contact force at the time of input and reduce a pull-out force at the time of vulcanization. The purpose.

The present invention is a tire provided with a sipe that opens to the tread of the tread, and the sipe is located inside the first sipe portion located on the side of the opening end to the tread portion and the first sipe portion in the radial direction of the tire. A bending portion connecting the second sipe portion, the first turning point which is the inner end of the first sipe portion in the radial direction of the tire, and the second turning point which is the outer end of the second sipe portion in the radial direction of the tire. The radius of curvature of the second sipe portion is larger than the radius of curvature of the bent portion, and the center of curvature of the second sipe portion and the center of curvature of the bent portion are on opposite sides of the sipe. The two sipe portions are characterized in that the radius of curvature becomes larger toward the inside in the radial direction of the tire, and the center of curvature is composed of a curve on one side of the sipe center line.
In this way, the center of curvature is opposite to the center of curvature of the second sipe portion between the first sipe portion located on the opening end side of the sipe and the second sipe portion located inside in the radial direction of the tire. Since the bending part on the side is provided and the radius of curvature of the second sipe part is made larger than the radius of curvature of the bending part, the sipe contact force is secured and the contact force at the time of input is secured, and the brewing pot is removed. The pull-out force at time can be reduced.
Further, the shape of the second sipe portion is formed by forming the second sipe portion with a curve whose radius of curvature becomes larger toward the inside in the radial direction of the tire and whose center of curvature is all on one side of the sipe center line. It becomes smoother, and the pull-out force at the time of pulling out of the vulcanization kettle can be further reduced.
Further, in the present invention, when the straight line connecting the outermost sipe, which is the opening end of the sipe to the tread, and the innermost sipe, which is the innermost in the tire radial direction, is the sipe centerline, the sipe is relative to the sipe centerline. It has a convex portion that bulges to one side in the tire circumferential direction or the tire width direction and a convex portion that bulges to the other side, and the sipe center line and the convex portion on the outer side in the tire radial direction of the convex portions. When the maximum value of the distance is the first amplitude and the maximum value of the distance between the sipe center line and the convex portion on the inner side in the tire radial direction of the convex portion is the second amplitude, the second amplitude is from the first amplitude. Is also small.
As a result, since a convex portion that greatly protrudes from the center line of the sipe is not formed inside the tire radial direction of the sipe, the pulling force at the time of pulling out of the vulcanization kettle can be surely reduced.
Further, in the present invention, the width w2 of the second sipe portion in the direction perpendicular to the tire radial direction in the plane perpendicular to the extension direction of the sipe on the tread surface is the width w2 of the sipe on the tread surface of the first sipe portion. It is characterized in that it is at least twice the width w1 in the direction perpendicular to the tire radial direction in the plane perpendicular to the extension direction.
As a result, the width of the second amplitude can be made appropriate, so that the pull-out force at the time of pulling out of the vulcanization pot can be reduced while ensuring the contact force of the 3D sipe.
When the extension direction of the tire tread of the sipe is the tire width direction, the width w1 and the width w2 are the widths in the tire circumferential direction, and when the extension direction is the tire circumferential direction, the widths w1 and the width w2 are the tire widths. Refers to the width of the direction.
In addition, both the center line of the sipe and the extension direction of the first sipe portion are inclined with respect to the tire radial direction, and the sipe is formed so that the inclined direction is opposite to the tire radial direction. The sipe contact force can be further increased, and the pull-out force at the time of pulling out of the vulcanization kettle can be further reduced.
Also, the size of the center line inclination angle is an acute angle side of the angle formed between the tread surface and the sipe centerline is an acute angle side of the angle formed between the tread surface and the extending direction of the first sipe portion It is characterized in that it is larger than the size of one sipe tilt angle.
As a result, the inclination of the sipe on the inner side in the tire radial direction can be reduced, so that the pull-out force at the time of pulling out of the vulcanization kettle can be further reduced.

It is a figure which shows one Embodiment of the tread pattern of a tire. It is a perspective view of a main part of a tread. It is a figure which shows the detail of a sipe shape. It is a figure which shows the arrangement example of a sipe. It is sectional drawing of the main part of a vulcanization mold. It is a figure for demonstrating the hook pull-out characteristic of the sipe formation at the time of tire molding. It is a figure for demonstrating the operation of a sipe at the time of input. It is a figure which shows the other arrangement example of a sipe. It is a figure which shows the other arrangement example of a sipe. It is a figure which shows the other arrangement example of a sipe. It is a figure which shows another example of a sipe. It is a main part perspective view of the tread according to another embodiment. It is a figure which shows the detail of the sipe shape which concerns on other embodiment. It is a figure for demonstrating the detail of a sipe shape. It is a figure which shows the arrangement example of a sipe. It is sectional drawing of the main part of a vulcanization mold. It is a figure for demonstrating the vulcanization kettle removal characteristic of the tire of this invention. It is a figure for demonstrating the operation of a sipe at the time of input. It is a figure which shows another shape of the sipe by this invention. It is a figure which shows the other arrangement example of a sipe. It is a figure which shows the other arrangement example of a sipe. It is a figure which shows the other arrangement example of a sipe. It is a figure which shows another example of a sipe.

Hereinafter, the present invention will be described in detail through embodiments of the invention, but the following embodiments do not limit the invention according to the claims, and all combinations of features described in the embodiments are the inventions. It is not always essential for the solution, but includes a configuration that is selectively adopted.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing an example of a tread pattern of the tire 10 according to the present embodiment, and FIG. 2 is a perspective view of a main part of the tread 11.
The tread 11 is composed of a circumferential groove 12 formed so as to extend along the tire circumferential direction, a lateral groove 13 extending along a direction intersecting the circumferential groove 12, and a circumferential groove 12 and a lateral groove 13. A plurality of partitioned blocks 14 and sipes 15 formed on the tire tread side of each block 14 are provided. The sign CL in FIG. 1 is a center line indicating the center of the tire 10 in the width direction. Further, in the following description, dimensions such as the length and angle of each part are defined by the central surface of the groove width of the sipe 15. The central surface of the sipe 15 in a plan view or a cross-sectional view is shown as a center line 15x, and dimensions such as the length and angle of each part are defined based on this.
The sipe 15 is a 3D sipe that extends in the direction parallel to the tire width direction on the surface (tread surface 14k) of the block 14 and changes its shape in the tire radial direction in the plane perpendicular to the tire width direction.
The surface shape of the tread surface 14k of the sipe 15 may be a straight line parallel to the tire width direction, but in this example, as shown in FIG. 1, the straight line portion 15 m parallel to the tire width direction and the tire width direction It has an inclined portion 15n that is inclined with respect to the other, and a straight portion 15m and an inclined portion 15n are alternately provided to form a trapezoidal wavy shape.

Specifically, as shown in the enlarged view of FIG. 1, the sipe 15 has a shape that opens to the tread surface 14k, one end of which is located on the extending direction center line c of the sipe 15, and the extending direction center line c. A first inclined section 31 that inclines and extends in a direction away from the above, and one end side is connected to the other end side of the first inclined section 31, and is separated by a predetermined distance in the direction along the extension direction center line c, for example, in a straight line. A second separated section 32 to be extended, one end side is connected to the other end side of the separated section 32, and the first inclined section 31 is inclined to the center line c in the extending direction at an angle θ where the separated section 32 intersects. The inclined section 33 is a basic shape, and the basic shape is alternately provided while sandwiching the center line c in the extending direction while being inverted to form a trapezoidal wavy shape. The extension direction center line c is a center line of wave height that swings in the intersecting direction with respect to the extension direction of the sipe 15 when the tread surface 14k is viewed in a plane. In addition, the term "inclined extension" includes vertical, acute, and obtuse angles except for those parallel to the extending direction of the sipe 15. Further, the direction along the extending direction center line c includes a direction parallel to the center line c or a direction toward the extending direction center line c as an inclination angle of ± 20 degrees. Further, none of the first inclined section 31, the second inclined section 33, and the separated section 32 is limited to a straight line, and may have a curved curvature.
Further, at the end portion in the extending direction, an extension portion 34 that is continuous with the first inclined section 31 and the second inclined section 33 and extends linearly along the center line c in the extending direction is provided. Then, the extension portion 34 opens in the groove wall for partitioning the block 14.
The sipe 15 has a one-cycle length L1 having a section length along the extending direction center line c of the first inclined section 31, the separated section 32, and the second inclined section 33 as a half cycle, and the one-cycle length L1 is when the tread 14k is viewed in a plane. It is composed of the first inclined section 31, the separated section 32, the second inclined section 33, the first inclined section 31, the separated section 32, and the second inclined section 33, and the sipe extension direction in each of the sections 31, 32, 33. It is the shortest dimension and is set in the range of 0.8 times to 2.0 times the groove depth D (see FIG. 3) of the sipe 15. Preferably, it may be set in the range of 1.08 times to 1.64 times.

Further, the wave height of the sipe 15 which is the dimension in the direction orthogonal to the extending direction center line c of the separated sections 32 and 32 located on both sides of the extending direction center line c is that of the sipe 15 formed in a trapezoidal shape. It is a dimension that doubles the length in the perpendicular direction from the center line c in the extending direction, which is the amplitude A, to the separation section 32, and is set in the range of 0.2 times to 2.0 times the groove depth D. Orthogonal. It is preferable to set it in the range of 0.3 times to 1.0 times.
The length L3 along the extending direction center line c of the separation section 32 is set in the range of 0.15 times to 0.4 times the groove depth D. It is preferable to set it in the range of 0.2 times to 0.35 times.
The length L3 is set in the range of 0.12 times to 0.28 times the one-cycle length L1. Preferably, it may be set in the range of 0.16 times to 0.24 times.
The length L2 along the extending direction center line c of the first inclined section 31 and the second inclined section 33 is set in the range of 0.2 to 0.6 times the groove depth D. It is preferable to set it in the range of 0.3 times to 0.5 times.
The length L3 is set in the range of 0.35 times to 0.94 times the length L2. It is preferable to set it in the range of 0.5 times to 0.8 times.
The angle θ at which the first inclined section 31 intersects the separated section 32 and the angle θ at which the second inclined section 33 intersects the separated section 32 are set in the range of 90 degrees to 175 degrees. More preferably, it is set in the range of 115 degrees to 160 degrees.

For example, as a preferable example for forming the sipe 15, the sipe 15 has an amplitude A of 1.0 mm ≦ A ≦ 1.2 mm, a length L3 of the separation section 32 of 1.0 mm ≦ L3 ≦ 1.6 mm, and a third. It is preferable that the angle θ at which the 1 inclined section 31 intersects the separated section 32 and the angle θ at which the second inclined section 33 intersects the separated section 32 are formed at 135 degrees ≦ θ ≦ 145 degrees.
As a result, the edge component can be provided not only in the tire circumferential direction but also in the tire width direction, so that the steering stability performance when traveling on ice can be improved.

As shown in FIG. 3, the sipe 15 has a first sipe portion 15p located on the opening end side to the tread surface 14k, which is the surface of the block 14, and a second sipe portion 15p located inside the first sipe portion 15p in the tire radial direction. A part 15q is provided. In this example, the first and second sipe portions 15p and 15q are made linear, and the distance dp between the wall surfaces of the first sipe portion 15p and the distance dq between the wall surfaces of the second sipe portion 15q are the same. That is, the distance between the wall surfaces facing each other in the sipe 15 was the same from the opening end side to the innermost side.
For example, the distance dp and the distance dq are set to, for example, 0.1 mm to 0.8 mm. It is preferable to set it to 0.2 mm to 0.5 mm.
Here, the outermost sipe, which is the open end of the sipe 15, is P0, the inner end P1 of the first sipe portion 15p in the radial direction of the tire (hereinafter referred to as the first inflection point P1), and the tire of the second sipe portion 15q. The innermost sipe P3 is the inner end in the radial direction, and the straight line passing through the outermost sipe P0 and the innermost sipe P3 is the sipe centerline m. The end portion P1 is also an end portion P2 (hereinafter referred to as a second inflection point P2) inside the second sipe portion 15q in the tire radial direction.
The sipe center line m of the sipe 15 is inclined toward the end side of the block 14 in the tire circumferential direction with respect to the tire radial direction, and is a straight line passing through the outermost sipe P0 and the first turning point P1. The first sipe inclination line n is inclined to the side opposite to the sipe center line m (the center side in the tire circumferential direction of the block 14).
Hereinafter, the angle formed by the sipe center line m and the tread 14k is the center line inclination angle α, the angle formed by the first sipe inclination line n and the tread 14k is the first sipe inclination angle β, the second sipe inclination line s and the tread 14k. Let the angle formed by be the second sipe inclination angle ω.
In this example, the centerline inclination angle α is set in the range of 60 degrees to 90 degrees, preferably in the range of 67 degrees to 82 degrees. The first sipe inclination angle β of the first sipe portion 15p is set in the range of 60 degrees to 90 degrees, preferably in the range of 70 degrees to 85 degrees. It is preferable that the center line inclination angle α and the first sipe inclination angle β are set so that the center line inclination angle α is larger than the first sipe inclination angle β while satisfying the above range.
Further, the second sipe inclination angle ω of the second sipe portion 15q is preferably set in the range of 30 degrees to 60 degrees, preferably in the range of 37 degrees to 52 degrees.
Further, in the first sipe portion 15p and the second sipe portion 15q, the first sipe inclination angle β and the second sipe inclination angle ω satisfy the above ranges, respectively, and the second sipe inclination angle ω with respect to the first sipe inclination angle β The ratio is preferably set in the range of 0.45 to 0.67. More preferably, it is set in the range of 0.50 to 0.61.
The radial depth d1, which is the length dimension of the first sipe portion 15p in the tire radial direction, is set to 0.25 times to 0.52 times the groove depth D in the tire radial direction of the sipe 15. Preferably, it is preferably set to 0.30 times to 0.44 times.
Further, the radial depth d3, which is the length dimension of the second sipe portion 15q in the tire radial direction, is set to 0.44 times to 0.81 times the groove depth D in the tire radial direction of the sipe 15. The radius. Preferably, it is preferably set to 0.53 times to 0.71 times.
Further, the radial depth d3 of the second sipe portion 15q is set to 0.8 to 5.0 times the radial depth d1 of the first sipe portion 15p. It is preferable to set it to 1.0 times to 3.4 times, more preferably 1.2 times to 2.5 times.
Further, the width of the first sipe portion 15p in the direction orthogonal to the tire radial direction when the sipe 15 is cross-sectionally viewed by a plane perpendicular to the direction in which the sipe 15 is continuous along the tread 14k is w1 and the width of the second sipe portion 15q. When the width is w2, w2 ≧ 2w1.
In the present embodiment, the width w2 of the second sipe portion 15q in the sipe 15 can be regarded as the total width, and is set in a dimension in the range of 0.18 times to 0.44 times the groove depth D, for example. To. It is preferable to set it in the range of 0.25 to 0.38.
Further, the width dimension W1 of the first sipe portion 15p in the cross-sectional view is set in the range of 0.01 times to 0.3 times the groove depth D. It is preferable to set it in the range of 0.05 times to 0.1 times.
Further, the width dimension W4 of the sipe center line m is set in the range of 0.1 times to 0.4 times the groove depth D. It is preferable to set it in the range of 0.2 times to 0.3 times.

In this example, as shown in FIG. 4, four sipes 151 to 154 are arranged so as to be line-symmetric with respect to the center line v of the block 14, and are located on the block end 14p and the block end 14p side. The distance from the sipe 151 and the distance b between the block end 14q and the sipe 154 on the block end 14q side are set to be equal to or greater than the distance a between adjacent sipes.
It is preferable that the interval a and the interval b have a relationship of a ≦ b ≦ 1.3a.
That is, when the interval b is smaller than a, the rigidity of the small blocks 141 and 145 on the block end 14p and 14q sides is reduced, so that the block edge effect is reduced. On the other hand, when the interval b exceeds 1.3a, the small blocks 141 and 145 on the block end 14p and 14q sides are likely to be lifted and the grounding performance is deteriorated. Therefore, it is preferable to set a ≦ b ≦ 1.3a. The distance a between adjacent sipes 15 and 15 is not constant, and may be set to be large on the end 14p and 14q sides of the block 14 and small on the center side. By inclining the sipe in this way, in addition to the deformation at the time of shear input, sipe contact due to the vertical load occurs, and the sipe contact force increases regardless of the input direction, so that the decrease in the ground contact area is suppressed. Can be done.

FIG. 5 is a cross-sectional view of a main part of the vulcanization mold 20 for vulcanizing the tire 10 shown in FIG. 4, and the sipes 151 to 154 are bone portions 21 for forming the circumferential groove 12 and the lateral groove 13. It is formed by a thin metal plate called a blade 24 which is provided so as to project in the direction of the cavity 23 from the groove 22 surrounded by the blade 24.
Each of the blades 24 (241 to 244) includes an embedded portion 24a embedded in the groove portion 22 and a protruding portion 24b having the same shape as the sipe 15. The protruding portion 24b is composed of a flat plate portion 24p corresponding to the first sipe portion 15p, a curved surface portion 24q corresponding to the second sipe portion 15q, and an arc portion 24r corresponding to the bent portion 15r, and the base Q0 of the flat plate portion 24p. Corresponds to the outermost P0 which is the open end of the sipe 15, and the tip Q3 of the curved surface portion 24q corresponds to the innermost P3 of the sipe 15.

In general, a 3D sipe having a bent portion in the middle tends to have a large pull-out force from the vulcanization mold 20 after vulcanization, but the sipe 15 of the present invention has a direction opposite to the tire radial direction. Since the blade 24 also includes a first sipe portion 15p that inclines toward the tire, the blade 24 also includes a flat plate portion 24p and a curved surface portion 24q that incline in directions opposite to each other in the radial direction of the tire. Therefore, when the blade 24 is pulled out, as shown in FIG. 6, the flat plate portion 24p pushes the small block on the center side of the block 14 adjacent to the first sipe portion 15p toward the center side of the block 14, and the curved surface portion 24q is the second. The sipe portion 15q pushes the small block at the end of the adjacent block 14 on the end side of the block 14. Therefore, the pulling force from the vulcanization mold 20 can be further reduced.

On the other hand, the formed sipe 15 has a macroscopic inclination (inclination having a centerline inclination angle α) connecting the tire tread side, which is the outermost sipe P0, and the innermost tire radial direction, which is the innermost sipe P3, and the tire. It has a local inclination (inclination having a first sipe inclination angle β) connecting the tread side and the bending start point (first inflection point P1), and has a macro inclination and a local inclination. Since they are opposite to each other in the tire radial direction, which is a vertical line to the tire tread, the sipe contact force can be increased regardless of the input direction.
Specifically, as shown in FIG. 7, assuming that a force from one end 14q side, which is the end of the block 14, to the other end 14p side, which is the end of the block 14, is input, the entry side (stepping side) At one end 14q side, the effect of the local inclination k acts on the end portion of the small block 146 which is the floating side, so that the floating of the small block 145 is suppressed. On the other hand, on the other end 14p side, which is the exit side (kicking side), the effect of the macro inclination K acts on the end of the small block 141 at the end, which is the floating side, so that the small block 141 at the end is lifted. Is suppressed. This is the same even if the input direction is opposite, so that the sipe contact force can be increased regardless of the input direction.

In this example, as described above, the center line inclination angle α> the first sipe inclination angle β, the center line inclination angle α is in the range of 60 to 90 degrees, and the first sipe inclination angle β is 60 degrees. The range is ~ 90 degrees. This is because when the center line inclination angle α is set to 90 degrees, the angle with respect to the tread surface 14k approaches the direction perpendicular to the tread, so that the pull-out force decreases but the sipe contact force may decrease. Further, when the center line inclination angle α is less than 60 degrees, the sipe contact force increases, but the pull-out force may also increase. Considering this point, the central core inclination angle α is preferably set in the range of 67 degrees to 82 degrees.
The same applies to the first sipe inclination angle β. When the first sipe inclination angle β is set to around 90 degrees, the pull-out force decreases by the amount of the gentle inclination, but the sipe contact force decreases, and the first sipe inclination angle β becomes If it is made smaller than 60 degrees, the sipe contact force increases, but the pull-out force may also increase.
Therefore, in this example, the center line inclination angle α and the first sipe inclination angle β are set in the above ranges, and the width w2 of the second sipe portion 15q is set to be twice or more the width w1 of the first sipe portion 15p. As a result, it is possible to reduce the pull-out force when the vulcanization pot is pulled out while ensuring the contact force of the 3D sipe.

Further, in the above-described embodiment, the center line inclination angle α and the first sipe inclination angle β of the four sipes 151 to 154 are the same, but as shown in FIG. 8, the center line inclination angle α and the first If the sipe inclination angle β is set so as to be large on the end 14p, 14q side of the block 14 and small on the center side, the edge effect of the sipe 151, 154 on the block end 14p, 14q side can be enhanced. At the same time, since the ground contact area can be secured in the small blocks 142 to 145 in the center, both the ground contact performance and the on-ice performance of the tire can be improved.

Further, in the above-described embodiment, the four sipes 151 to 154 are arranged so as to be line-symmetric with respect to the center line v of the block 14, but the number of sipes 15 is not limited to this, and the block 14 is not limited to this. It suffices if a plurality of them are formed in. Further, as for the arrangement, as shown in FIG. 9, all the directions of the sipe center line m may be the tire circumferential direction. The arrangement shown in FIG. 9 is particularly effective when the input from one direction is large, such as giving priority to braking characteristics.
Further, as shown in FIG. 10A, when there is a sipe in the center of the block 14, it is preferable that the sipe 15C located at the center is a 2D sipe. As a result, the same sipe contact force can be obtained even if the input directions are opposite.
Further, as shown in FIG. 10B, even when there is no sipe in the center of the block 14, the sipe 15C and 15C may be set adjacent to the center of the block to form a 2D sipe.
As shown in FIG. 10C, even when the sipe is located at the center of the block 14, the sipe 15C located at the center and the sipe 15C'adjacent to the sipe 15C may be used as a 2D sipe.
As described above, since the blade having a simple structure can be used for the sipe near the center of the block, which contributes less to the lifting of the small block, the tire can be easily manufactured.

Further, in the above-described embodiment, the surface shape of the sipe 15 is trapezoidal and wavy, but it is a 2D sipe having a zigzag shape or a straight portion parallel to the tire width direction and a slope portion inclined with respect to the tire width direction. May be.
Further, in the above embodiment, the sipe 15 is a 3D sipe extending in a direction parallel to the tire width direction, but as shown in FIG. 11A, a sipe extending in a direction parallel to the tire circumferential direction. It may be 18 (181 to 184). In this case, among the sipes 181 to 184, the sipes 181 to 184 are set so that the radial inclination angle of the tire end side sipes 181 and 184 is larger than the radial inclination angle of the central sipes 182 to 184. It may be formed. As a result, when the block 14 receives an input parallel to the tire width direction such as a lateral force, it is possible to effectively suppress the floating of the small blocks partitioned by the sipes 181 to 184 from the road surface.
Further, as shown in FIG. 11B, if a sipe 19 extending in a direction intersecting the tire circumferential direction and the tire width direction is provided, the sipe 19 is partitioned against inputs from multiple directions. It is possible to effectively suppress the lifting of small blocks from the road surface. In this case, the absolute value of the radial inclination angle of one and the other sipes of the sipes 19 located on the tire circumferential end side of the block 14 is that of the sipes other than the one and the other sipes. It may be larger than the absolute value of the radial inclination angle. In FIG. 11B, the shape of the block 14 seen from the tire tread side is shown as two sides 14a and 14c parallel to the tire circumferential direction and two parallel to each other intersecting the tire circumferential direction and the width direction. It was a parallel quadrilateral consisting of sides 14b and 14d.
Further, as shown in FIG. 11C, in the sipe 15 of the above-described embodiment, the rib-shaped land portion 16 (or the rib-shaped land portion 16) that contributes to the edge effect on the front-rear force such as a brake is partitioned by a lateral groove. In the center block), the sipe 18 is in the shoulder block 14C which contributes to the edge effect on the lateral force, and the sipe 19 is in the intermediate block 14B arranged between the ribbed land portion 16 and the shoulder block 14C. It is preferable to provide.
As a result, it is possible to effectively prevent the small blocks of the ribbed land portion 16 and the blocks 14B and 14C, which are partitioned by the sipes 15, 18 and 19, from floating from the road surface. Therefore, it is possible to effectively improve the ground contact performance of the tire while ensuring the performance on ice not only for the front-rear force but also for the lateral force.
Further, in the above-described embodiment, the extension direction of the circumferential groove 12 is parallel to the tire circumferential direction, and the extension direction of the lateral groove 13 is parallel to the tire width direction. The grooves adjacent to each other in the circumferential direction of the tire may have a zigzag shape in which they are inclined in opposite directions. Further, the lateral groove 13 may also be a straight line or a curved line inclined with respect to the tire circumferential direction.
Further, the sipe 15 may extend only in the tire width direction or the tire circumferential direction, or may be inclined with respect to the tire circumferential direction.

Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the embodiments. It will be apparent to those skilled in the art that various changes or improvements can be made to the above embodiments. It is clear from the claims that forms with such modifications or improvements may also be included in the technical scope of the invention.

FIG. 12 is a perspective view of a main part of the tread 11 according to another embodiment. FIG. 13 is a diagram showing details of the sipe shape according to another embodiment.
For example, in the above embodiment, the second sipe portion 15q is linear, but as shown in FIGS. 12 and 13, the second sipe portion 15q is curved and the tire radius of the first sipe portion 15p. The end portion P1 on the inner side in the direction and the end portion P2 on the outer side in the radial direction of the tire of the second sipe portion 15q may be connected by an arc-shaped bent portion 15r.

That is, as shown in FIG. 13A, the sipe 15 according to the present embodiment has an opening end to the tread 14k when the sipe 15 is cross-sectionally viewed by a plane perpendicular to the extending direction of the sipe 15 on the tread 14k. The first sipe portion 15p located on the side, the second sipe portion 15q located inside the first sipe portion 15p in the tire radial direction, and the end portions P1 and the second sipe portion inside the tire radial direction of the first sipe portion 15p. It is provided with an arc-shaped bent portion 15r connecting the end portions P2 on the outer side in the radial direction of the tire of 15q. In the sipe 15 of the present embodiment, the groove walls 15a and 15b facing each other that partition the sipe 15 extend in the depth direction from the tread surface 14k toward the inside in the radial direction of the tire while maintaining the same width. That is, the sipe 15 is molded by the metal thin plate 24 (blade) having a constant thickness provided in the vulcanization mold 20 in FIG.
Further, in the present embodiment, for convenience of explanation, the first sipe portion 15p and the second sipe portion 15q will be described as being directly continuous with the bent portion 15r. That is, the first inflection point P1 is not only one end of the bent portion 15r but also the end of the first sipe portion 15p. The second inflection point P2 is the other end of the bent portion 15r and also the end of the second sipe portion 15q. A straight line or curved line connecting the ends between the first sipe portion 15p and the bent portion 15r, or a straight line or curved line connecting the ends between the second sipe portion 15q and the bent portion 15r. There may be a connection. In this case, both ends of the bent portion 15r are inflection points whose curvature changes from the connecting portion.

As shown in FIG. 13B, assuming that the straight line passing through the outermost sipe P0, which is the open end of the sipe 15, and the innermost sipe P3, which is the innermost in the radial direction of the tire, is the sipe center line m, the sipe center of the sipe 15. The line m is inclined with respect to the tire radial direction. Hereinafter, the angle formed by the tread surface 14k and the sipe center line m is referred to as the center line inclination angle α.
On the other hand, the first sipe portion 15p is linear. Here, assuming that the straight line passing through the outermost sipe P0 and the first inflection point P1 is the first sipe slope line n, the first sipe slope line n of the sipe 15 is on the opposite side (block) from the sipe center line m. It is inclined toward the center side of the tire circumference of 14. Further, the first sipe inclination angle β, which is the angle formed by the tread surface 14k and the first sipe inclination line n, is smaller than the center line inclination angle α.
The center line inclination angle α is set in the range of 60 degrees to 90 degrees, preferably in the range of 67 degrees to 82 degrees. The first sipe inclination angle β of the first sipe portion 15p is set in the range of 60 degrees to 90 degrees, preferably in the range of 70 degrees to 85 degrees. As will be described later, the fact that the first sipe inclination line n is inclined to the side opposite to the sipe center line m and that the first sipe inclination angle β is larger than the center line inclination angle α is the present invention. It is not an essential requirement of the invention.

The radius of curvature R of the second sipe portion 15q is larger than the radius of curvature r of the bent portion 15r so that the inclination angle of the tangent to the tread 14k gradually increases from the outer end in the tire radial direction to the inner end in the tire radial direction. The center of curvature of the bent portion 15r is on the end side of the block 14 in the tire circumferential direction, and the center of curvature of the second sipe portion 15q is on the side of the center of the block 14 in the tire circumferential direction. That is, the center of curvature of the second sipe portion 15q and the center of curvature of the bent portion 15r are on opposite sides of the sipe 15. It is desirable that the inclination angle of the tangent line of the sipe 15 at the innermost sipe P3 is formed so as to extend perpendicularly to, for example, the tread 14k. Further, the innermost P3 side of the sipe may include a straight line portion, and the radius of curvature of the second sipe portion may be increased to asymptotic to a straight line having an infinite radius of curvature.
If it is a straight line, the hook can be easily pulled out, and the ground contact area can be secured by sufficiently suppressing the block from collapsing due to sipe contact at the portion outside the straight line portion in the radial direction of the tire.
The inclination angle of the outer end of the second sipe portion 15q in the radial direction of the tire is set to 30 degrees to 60 degrees, preferably 37 degrees to 52 degrees.

The radial depth d1, which is the length dimension of the first sipe portion 15p in the tire radial direction, is set to 0.25 times to 0.52 times the groove depth D in the tire radial direction of the sipe 15. Preferably, it is set to 0.30 times to 0.44 times.
Further, the radial depth d3, which is the length dimension of the second sipe portion 15q in the tire radial direction, is set to 0.44 times to 0.81 times the groove depth D in the tire radial direction of the sipe 15. The radius. Preferably, it is set to 0.53 times to 0.71 times. Further, the radial depth d3 of the second sipe portion 15q is set to 0.8 to 5.0 times the radial depth d1 of the first sipe portion 15p. It is preferable to set it to 1.0 times to 3.4 times, more preferably 1.2 times to 2.5 times.

Further, the width dimension W3 of the sipe 15 as a whole in the cross-sectional view is set in the range of 0.18 times to 0.44 times the groove depth D. It is preferable to set it in the range of 0.25 to 0.38. This width dimension W3 is approximately the width of the second sipe portion 15q except for the bent portion 15r.
Further, the width dimension W1 of the first sipe portion 15p in the cross-sectional view is set in the range of 0.01 times to 0.3 times the groove depth D. It is preferable to set it in the range of 0.05 times to 0.1 times.
Further, the width dimension W4 of the sipe center line m is set in the range of 0.1 times to 0.4 times the groove depth D. It is preferable to set it in the range of 0.2 times to 0.3 times.
The width dimensions W1, W3, and W4 are measured in a direction orthogonal to the tire radial direction when the sipe 15 is viewed in cross section by a plane perpendicular to the continuous direction of the sipe 15 along the tread surface 14k.
The sipe 15 is the thickness dimension of the first sipe portion 15p, the bent portion 15r, and the second sipe portion 15q.
The distance dp between the wall surfaces of the first sipe portion 15p, the distance dr between the wall surfaces of the bent portion 15r, and the distance dq between the wall surfaces of the second sipe portion 15q were set to be the same. That is, the distance between the wall surfaces facing each other in the sipe 15 was the same from the opening end side to the innermost side. For example, the distances dp, dr, and dq are set to, for example, 0.1 mm to 0.8 mm. It is preferable to set it to 0.2 mm to 0.5 mm.

Further, as shown in FIG. 13C, the sipe 15 has a convex portion 15u swelling toward the center side of the block 14 and a convex portion 15v bulging toward the end side of the block 14 with respect to the sipe center line m. ing. Here, the convex portion 15u on the outer side in the radial direction of the tire is the convex portion on the tread side, the convex portion 15v on the inner side in the radial direction of the tire is the inner convex portion, and the maximum value of the distance between the sipe center line m and the convex portion 15u on the tread side is the first. When the maximum value of the distance between one amplitude Wp and the sipe center line m and the inner convex portion 15v is the second amplitude Wq, Wq <Wp and as shown in FIG. 13D, along the tread 14k. When the width of the first sipe portion 15p in the direction orthogonal to the tire radial direction when the sipe 15 is viewed in cross section by a plane perpendicular to the continuous direction of the sipe 15 is W1, and the width of the second sipe portion 15q is W2. , W2 ≧ 2 W1. The first amplitude Wp is the maximum value of the shortest distance from each point of the tread side convex portion 15u to the sipe center line m, and the second amplitude Wq is the shortest value from each point of the inner convex portion 15v to the sipe center line m. The maximum value of the distance. In FIG. 13C, the first amplitude Wp is set to almost 0. Further, the inner convex portion 15v'in which Wq'> Wp shown by the broken line in the figure does not satisfy the above condition.

Further, the shortest distance W3 from the end Pu that protrudes most toward the block center side of the tread side convex portion 15u to the innermost P3 of the sipe is preferably 1.2 mm ≦ W3 ≦ 2.2 mm. Further, the radial depth d2 from the end Pu to the innermost P3 of the sipe is preferably 4.0 mm ≦ d2 ≦ 5.5 mm.
Further, in the sipe 15, the maximum width W5 in the cross-sectional region z is set in a range of 0.4 to 1.2 times the groove depth D up to the innermost sipe P3. It is preferable to set it in the range of 0.6 times to 1.0 times.
The cross-sectional region z refers to a portion surrounded by the groove walls 15a and 15b and the groove bottom 15c forming the sipe 15 in the cross-sectional view, and the maximum width W5 in the cross-sectional region z is from one groove wall 15a to the tread 14k. It refers to the dimension that maximizes the length dimension of the straight line extending in the radial direction of the tire and the straight line extending in the radial direction of the tire from the other groove wall 15b toward the tread 14k.

As shown in FIG. 14A, the sipe 15 includes a first sipe portion 15p located on the tread 14k side, a second sipe portion 15q located inside the first sipe portion 15p in the tire radial direction, and a first sipe portion 15. It has a bent portion 15r connecting a first turning point P1 which is an inner end in the tire radial direction of the sipe portion 15p and a second turning point P2 which is an outer end in the tire radial direction of the second sipe portion 15q. A straight line f1 connecting the innermost sipe P3 and the second turning point P2, which is the inner end of the sipe 15 in the tire radial direction shown in FIG. 14B, and a tangent line f2 at the outer end of the second sipe portion in the tire radial direction. With respect to the area S1 surrounded by the tangent line f3 at the inner end of the second sipe portion 15q in the tire radial direction, the tangent line f2 at the outer end of the second sipe portion 15q in the tire radial direction shown in FIG. 14C. The ratio of the area S2 surrounded by the tangent line f3 and the second sipe portion 15q at the inner end of the second sipe portion 15q in the tire radial direction is preferably 0.05 or more and less than 1.0.

In the present embodiment, as described above, the first sipe portion 15p and the second sipe portion 15q are directly continuous with the bent portion 15r, so that the area S1 is inside the second sipe portion 15q in the tire radial direction. The straight line f1 connecting the inflection point P2 and the innermost sipe P3 in the radial direction of the tire, the tangent line f2 at the inflection point P2 outside the radial direction of the tire, and the tangent line f3 at the innermost sipe P3 inside the radial direction of the tire. The enclosed portion, the area S2, is formed by the extension center line 15x of the second sipe portion 15q, the tangent line f2 at the inflection point P2 outside the tire radial direction, and the tangent line f3 at the innermost sipe P3 inside the tire radial direction. It is an enclosed part.

Further, in the sipe 15, the area S2 shown in FIG. 14 (c) is tangent to the end of the bent portion 15r on the first sipe portion 15p side shown in FIG. 14 (d), and the second sipe portion 15q of the bent portion 15r. It is preferably larger than the area S3 surrounded by the tangent line at the side end and the bent portion 15r. That is, the area S2 is bent by the tangent line f4 at the inflection point P1 which is the outer end point of the bent portion 15r in the tire radial direction and the tangent line f2 at the inflection point P2 which is the inner end point of the bent portion 15r in the tire radial direction. It is formed so as to be larger than the area S3 surrounded by the portion 15r.
Further, the sipe 15 has an end on the tread surface 14k side of the first sipe portion 15p shown in FIG. 14 (e) (P0 in the present embodiment) and an inner end in the tire radial direction of the second sipe portion 15q (P3 in the present embodiment). The ratio of the area S2 to the area S4 surrounded by the straight line connecting the) and the sipe 15 is preferably in the range of 0.1 or more and 0.9 or less.

Further, as shown in FIG. 14A, in the sipe 15, the inclination angle γ1 at the tread-side end (P0 in the present embodiment) of the first sipe portion 15p with respect to the tread 14k is the second inflection point P2. It is preferable that the inclination angle is larger than γ2. The inclination angle γ1 is an acute-angled angle between the tangent line f5 and the tread surface 14k at the tread side end (P0 in this embodiment) of the first sipe portion 15p. When the first sipe portion 15p is a straight line and is directly connected to the bent portion 15r, the inclination angle γ1 is equal to the inclination angle β of the first sipe inclination line n.
Further, in the sipe 15, the inclination angle γ3 at the inner end (P3 in the present embodiment) of the second sipe portion 15q in the tire radial direction with respect to the tread 14k is larger than the inclination angle γ2 at the second inflection point P2. Is preferable. The inclination angle γ2, which is the outer end of the second sipe portion 15q in the tire radial direction, is set in the range of, for example, 30 degrees to 60 degrees. Preferably, it is set in the range of 37 degrees to 52 degrees. The inclination angle γ2 is set in the range of 0.45 times to 0.67 times the first sipe inclination angle β. Preferably, it may be set in the range of 0.5 times to 0.61 times.

FIG. 14 (f) is a view in which the sipe 15 is projected on a plane perpendicular to the tread 14k parallel to the extending direction of the sipe 15. As shown in the figure, as described above, in setting the angle and length of each part, the sipe 15 extends when projected onto a plane perpendicular to the tread 14k parallel to the extending direction of the sipe 15. The area Sp and the second sipe occupied by the first sipe portion 15p with respect to the total area Sa (extension direction length L x groove depth D) when the sipe 15 is projected on a plane perpendicular to the tread surface 14k parallel to the direction. The area Sq occupied by the portion 15q is set so as to have the following relationship.
The area Sp of the first sipe portion 15p is set in the range of 0.22 times to 0.54 times the total area Sa. It is preferable to set it in the range of 0.3 times to 0.46 times.
The area Sq of the second sipe portion 15q is set in the range of 0.48 times to 0.82 times the total area Sa. Preferably, it may be set in the range of 0.52 times to 0.72 times.

In this example, as shown in FIG. 15, four sipes 151 to 154 are arranged so that the extending directions of the sipes on the tread are parallel to each other and line-symmetrical with respect to the center line v of the block 14. The distance between the block end 14p and the sipe 151 on the block end 14p side and the distance b between the block end 14q and the sipe 154 on the block end 14q side are set to be equal to or greater than the distance a between adjacent sipes. In addition to being completely parallel, the term "parallel" includes an inclination of ± 20 degrees or less.
It is preferable that the interval a and the interval b have a relationship of a ≦ b ≦ 1.3a. That is, when the interval b is smaller than a, the rigidity of the small blocks 141 and 145 on the block end 14p and 14q sides is reduced, so that the block edge effect is reduced. On the other hand, if the interval b exceeds 1.3a, the small blocks 141 and 145 on the block end 14p and 14q sides are likely to be lifted, and the grounding performance is deteriorated. Therefore, it is preferable to set a ≦ b ≦ 1.3a.

Further, the sipe 151 to 154 are set in a range in which the shortest sipe distance x, which is the shortest distance from the adjacent sipe, is 0.4 to 1.2 times the groove depth D. It is preferable to set it in the range of 0.6 times to 1.0 times. The shortest sipe distance x means, for example, when the sipe center line m is provided so as to be inclined in the same direction as in sipe 151, 152, the groove wall 151a for partitioning the small block 142 and the groove wall 152b It refers to the shortest distance, and when the sipe center lines m are provided so as to intersect each other as in sipe 152 and 153, it means the shortest distance between the groove wall 152a and the groove wall 153a that partition the small block 143.
The distance a between the sipes 151 to 154 set by the shortest sipes distance x is preferably 2.4 mm ≦ a ≦ 7.0 mm. By setting the interval a of the sipes 15 in this way, the block rigidity of the small blocks 142 to 144 can be secured.
The distance a between adjacent sipes 15 and 15 is not constant, and may be set to be large on the block end 14p and 14q sides and small on the center side.
By inclining the sipe 15 in this way, in addition to the deformation at the time of shear input, the sipe contact occurs due to the vertical load, and the sipe contact force increases regardless of the input direction, so that the decrease in the ground contact area is suppressed. can do.

FIG. 16 is a cross-sectional view of a main part of the vulcanization mold 20 for vulcanizing the tire 10 shown in FIG. 15, and the sipes 151 to 154 are bone portions 21 for forming the circumferential groove 12 and the lateral groove 13. It is formed by a thin metal plate called a blade 24 which is provided so as to project in the direction of the cavity 23 from the groove 22 surrounded by the blade 24.
Each of the blades 24 (241 to 244) includes an embedded portion 24a embedded in the groove portion 22 and a protruding portion 24b having the same shape as the sipe 15. The protruding portion 24b is composed of a flat plate portion 24p corresponding to the first sipe portion 15p, a curved surface portion 24q corresponding to the second sipe portion 15q, and an arc portion 24r corresponding to the bent portion 15r, and the base Q0 of the flat plate portion 24p. Corresponds to the outermost P0 which is the open end of the sipe 15, and the tip Q3 of the curved surface portion 24q corresponds to the innermost P3 of the sipe 15.

In general, a 3D sipe having a bent portion in the middle tends to have a large pull-out force from the vulcanization mold 20 after vulcanization. However, as shown in FIG. 13A, the sipe 15 of the present invention has a sipe 15 of the present invention. Since the bent portion 15r has an arc shape and the second sipe portion 15q located inside in the radial direction of the tire has a gentle curve (arc shape with a large radius of curvature), the first sipe portion 15p and the second sipe portion 15q As a result, the pull-out force when the vulcanization pot is pulled out can be significantly reduced while ensuring the sipe contact force.
Further, since the blade 24 includes a flat plate portion 24p and a curved surface portion 24q that are inclined in opposite directions with respect to the tire radial direction, the flat plate portion 24p is as shown in FIG. 17 when the blade 24 is pulled out. The small block on the center side of the block 14 adjacent to the first sipe portion 15p is pushed toward the center side of the block 14, and the curved surface portion 24q pushes the small block at the end of the block 14 adjacent to the second sipe portion 15q to the end of the block 14. You will push the part side. Therefore, the pulling force from the vulcanization mold 20 can be further reduced.

On the other hand, the formed sipe 15 has a macroscopic inclination (inclination having a centerline inclination angle α) connecting the tire tread side, which is the outermost sipe P0, and the innermost tire radial direction, which is the innermost sipe P3, and the tire. It has a local inclination (inclination having a first sipe inclination angle β) connecting the tread side and the bending start point (first inflection point P1), and the macro inclination and the local inclination are Since they are opposite to each other in the tire radial direction, which is a vertical line to the tire tread, the sipe contact force can be increased regardless of the input direction.
Specifically, as shown in FIG. 18, assuming that a force from one end side (14q side) to the other end side (14p side) of the block 14 is input, a local inclination is made on the one end 14q side, which is the input side. Since the effect of k acts on the end portion of the small block 145 on the floating side, the floating of the small block 145 is suppressed. On the other hand, on the other end side, which is the exit side, the effect of the macro inclination K acts on the end portion of the small block 141 at the end portion, which is the floating side, so that the floating of the small block 141 at the end portion is suppressed. This is the same even if the input direction is opposite, so that the sipe contact force can be increased regardless of the input direction.

As described above, the center line inclination angle α is preferably set in the range of 60 degrees to 90 degrees. When the center line inclination angle α is set to 90 degrees, the angle with respect to the tread surface 14k approaches in the direction perpendicular to the tread surface, so that the pull-out force decreases but the sipe contact force may decrease. Further, when the center line inclination angle α is less than 60 degrees, the sipe contact force increases, but the pull-out force may also increase. Considering this point, the central core inclination angle α is preferably set in the range of 67 degrees to 82 degrees.
The same applies to the first sipe inclination angle β, but as shown in FIG. 13A, the sipe 15 of the present invention has a radius of curvature R larger than the radius of curvature r of the bent portion 15r and the bent portion 15r. Since the 2 sipe portion 15q is provided, even if β> 90 (the first sipe portion 15p is inclined in the same direction as the sipe center line m), the vulcanization kettle can be removed while ensuring the sipe contact force. The pull-out force at time can be reduced.
Further, as shown in FIG. 13 (c), it is preferable that the second amplitude Wq is smaller than the first amplitude Wp. This is because, as shown by the broken line in FIG. 13C, when the second amplitude Wq is made larger than the first amplitude Wp, a convex portion that greatly protrudes from the sipe center line m is formed inside the 15 tire radial directions of the sipe. This is because the pull-out force when the vulcanizing pot is pulled out increases.
On the other hand, if the second amplitude Wq is narrowed in order to improve the hook removal property, the contact force of the 3D sipe is reduced. Therefore, in this example, Wq <Wp and, as shown in FIG. 13D, the width W2 of the second sipe portion 15q is set to be twice or more the width W1 of the first sipe portion 15p. While ensuring the contact force of the 3D sipe, the pull-out force at the time of pulling out of the vulcanization pot can be reduced.

For example, in the above embodiment, the second sipe portion 15q has an arc shape having a radius of curvature of R, but it may have a curved shape (the curvature also includes a straight line having a very large radius of curvature). Further, as shown in FIG. 19A, it may be a curved shape composed of a plurality of arcs Ck (k = 1 to n) having different radii of curvature R1, R2, ..., Rn. In this case, it goes without saying that the centers of curvature of each arc Ck are all located on the opposite side of the center of curvature of the first sipe portion 15p.
Further, when the arc on the bent portion 15r side is C1 and the arc on the innermost P3 side of the sipe is Cn, the radius of curvature Rk of each arc Ck (k = 1 to n) is increased toward the inside in the tire radial direction. For example, the shape of the second sipe portion 15q becomes smoother, and the distance from the sipe center line m becomes smaller toward the inside in the radial direction of the tire, so that the pull-out force at the time of pulling out the brewing pot can be further reduced. ..
Further, as shown in FIG. 19B, the deepest portion of the second sipe portion 15q may be a straight line (Rn = ∞).
The radius of curvature Rk and Rk + 1 of two adjacent arcs Ck and Ck + 1 do not necessarily satisfy the relationship of Rk <Rk + 1, but it is better to set Rk <Rk + 1 as in this example. It is preferable because the shape of 15q can be made smoother.
The bent portion 15r may also be curved and may not be arcuate.

Further, in the above-described embodiment, the center line inclination angle α and the first sipe inclination angle β of the four sipes 151 to 154 are the same, but as shown in FIG. 20, the center line inclination angle α and the first If the sipe inclination angle β is set to be large on the block end 14p, 14q side and small on the center side, the edge effect of the sipe 151, 154 on the block end 14p, 14q side can be enhanced. Since the ground contact area can be secured in the small blocks 142 to 144 in the center, both the ground contact performance of the tire and the on-ice performance can be improved.

Further, in the above-described embodiment, the four sipes 151 to 154 are arranged so as to be line-symmetric with respect to the center line v of the block 14, but the number of sipes 15 is not limited to this, and the block 14 is not limited to this. It suffices if a plurality of them are formed in. Further, as for the arrangement, as shown in FIG. 21, all the directions of the sipe center line m may be the tire circumferential direction. The arrangement shown in FIG. 21 is particularly effective when the input from one direction is large, such as giving priority to braking characteristics.
Further, as shown in FIG. 22A, when there is a sipe in the center of the block 14, it is preferable that the sipe 15C located at the center is a 2D sipe. As a result, the same sipe contact force can be obtained even if the input directions are opposite.
Further, as shown in FIG. 22B, even when there is no sipe in the center of the block 14, the sipe 15c and 15c may be set adjacent to the center of the block to form a 2D sipe.
As shown in FIG. 22C, even when there is a sipe in the center of the block 14, the sipe 15C located at the center and the sipe 15C'adjacent to the sipe 15C may be used as a 2D sipe. ..
As described above, since the blade having a simple structure can be used for the sipe near the center of the block, which contributes less to the lifting of the small block, the tire can be easily manufactured.

Further, in the above-described embodiment, the surface shape of the sipe 15 is trapezoidal and wavy, but as a 2D sipe having a zigzag shape or a straight portion parallel to the tire width direction and an inclined portion inclined with respect to the tire width direction. May be good.
Further, in the above-described embodiment, the sipe 15 is a 3D sipe that extends in a direction parallel to the tire width direction, but as shown in FIG. 23A, a sipe extending in a direction parallel to the tire circumferential direction. It may be 18 (181 to 184). In this case, among the sipes 181 to 184, the sipes 181 to 184 so that the inclination angle in the tire radial direction of the tire end side sipes 181 and 184 is larger than the radial inclination angle of the central sipes 182 and 183. 184 may be formed. As a result, when the block 14 receives an input parallel to the tire width direction such as a lateral force, it is possible to effectively suppress the floating of the small blocks partitioned by the sipes 181 to 184 from the road surface.
Further, as shown in FIG. 23B, if a sipe 19 extending in a direction intersecting the tire circumferential direction and the tire width direction is provided, the sipe 19 is used for input from multiple directions. It is possible to effectively suppress the lifting of small blocks from the road surface. In this case, the absolute value of the radial inclination angle of one and the other sipes of the sipes 19 located on the tire circumferential end side of the block 14 is that of the sipes other than the one and the other sipes. It may be larger than the absolute value of the radial inclination angle. In FIG. 23B, the shape of the block 14 viewed from the tire tread side is shown as two sides 14a and 14c parallel to the tire circumferential direction and two parallel to each other intersecting the tire circumferential direction and the width direction. It was a parallel quadrilateral consisting of sides 14b and 14d.
Further, as shown in FIG. 23 (c), in the sipe 15 of the above-described embodiment, the rib-shaped land portion 16 (or the rib-shaped land portion 16) that contributes to the edge effect on the front-rear force of the brake or the like is partitioned by a lateral groove. In the center block), the sipe 18 is in the shoulder block 14C which contributes to the edge effect on the lateral force, and the sipe 19 is in the intermediate block 14B arranged between the ribbed land portion 16 and the shoulder block 14C. It is preferable to provide.
As a result, it is possible to effectively prevent the small blocks of the ribbed land portion 16 and the blocks 14B and 14C, which are partitioned by the sipes 15, 18 and 19, from floating from the road surface. Therefore, it is possible to effectively improve the ground contact performance of the tire while ensuring the performance on ice not only for the front-rear force but also for the lateral force.
Further, in the above-described embodiment, the extension direction of the circumferential groove 12 is parallel to the tire circumferential direction, and the extension direction of the lateral groove 13 is parallel to the tire width direction. The grooves adjacent to each other in the circumferential direction of the tire may have a zigzag shape in which they are inclined in opposite directions. Further, the lateral groove 13 may also be a straight line or a curved line inclined with respect to the tire circumferential direction.
Further, the sipe 15 may extend only in the tire width direction or the tire circumferential direction, or may be inclined with respect to the tire circumferential direction.

10 tires, 11 treads, 12 circumferential grooves, 13 lateral grooves, 14 blocks,
15,151-156 sipes, 15m straight part, 15n inclined part,
15p 1st sipe part, 15q 2nd sipe part, 15r bent part,
16 Ribbed land area.

Claims (5)

A tire with a sipe that opens to the tread of the tread.
The sipe is
The first sipe portion located on the opening end side to the tread surface,
The second sipe portion located inside the tire radial direction of the first sipe portion and
It has a bent portion connecting a first inflection point which is an inner end in the tire radial direction of the first sipe portion and a second inflection point which is an outer end in the tire radial direction of the second sipe portion.
The radius of curvature of the second sipe portion is larger than the radius of curvature of the bent portion.
And the center of curvature of the center of curvature of the second sipe portion the bent portion, Ri opposite near each other across the sipe,
It said tire second sipe portion is greater as the radius of curvature goes to the inner side in the tire radial direction, and that from the curve center of curvature is on one side of all the sipes centerline, wherein forming Rukoto. When the straight line connecting the outermost sipe, which is the opening end of the sipe to the tread, and the innermost sipe, which is the innermost in the tire radial direction, is the sipe center line.
The sipe has a convex portion that bulges toward one side in the tire circumferential direction or the tire width direction and a convex portion that bulges toward the other side with respect to the sipe center line.
The maximum value of the distance between the sipe center line and the convex portion on the outer side in the tire radial direction among the convex portions is set as the first amplitude.
When the maximum value of the distance between the sipe center line and the convex portion on the inner side in the tire radial direction of the convex portion is the second amplitude,
The tire according to claim 1, wherein the second amplitude is smaller than the first amplitude. The width of the second sipe portion in the direction perpendicular to the tire radial direction in the plane perpendicular to the extension direction of the sipe on the tread is perpendicular to the extension direction of the sipe on the tread of the first sipe portion. The tire according to claim 1 or 2, wherein the width is at least twice the width in the direction perpendicular to the tire radial direction in a plane. Inclined with respect to the extending direction are both tire radial direction before Symbol sipe centerline and the first sipe portion, and the inclination direction is formed to be in the opposite direction to the tire radial direction The tire according to any one of claims 1 to 3 , wherein the tire is characterized by. The sipe size of centerline inclination angle is an acute angle side of the angle formed by the center line and said tread surface, wherein the first sipe is acute side of the angle formed by the extending direction and the tread surface of the first sipe portion The tire according to any one of claims 1 to 4, wherein the tire is larger than the size of the inclination angle.