JP2013116725A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire that has a land portion with a sipe such that all of snow performance, dry performance, and wet performance can be simultaneously achieved at a high degree within the single land portion.SOLUTION: The pneumatic tire includes a tread portion having a land portion 2 provided with a sipe 3 extending in a tire width direction while oscillating in a tire circumferential direction. The sipe 3 includes, with respect to a depth direction from a land portion surface S to the inside in a tire radial direction: a land portion surface side portion 3athat is bent in the tire circumferential direction from the land portion surface S; and a land portion bottom side portion 3athat is bent in a direction different from the land portion surface side portion 3aor in the tire circumferential direction with a displacement different from the displacement of the land portion surface side portion 3a.

Description

  The present invention is a pneumatic tire having a land portion in a tread portion and provided with a sipe extending in the tire width direction with an amplitude in the tire circumferential direction on the land portion, in particular, snow performance, dry performance, The present invention relates to a pneumatic tire that realizes all wet performance at the same time at a high level.

  Conventionally, in a tire for traveling on a snowy road surface, in order to improve braking performance and traction performance on a snowy road, a plurality of tires extending along the tire width direction with respect to a land part provided on a tread part are provided. A sipe is formed and an edge component is provided. As such a sipe, there is known a two-dimensional sipe having a zigzag shape or a corrugated shape on the tread surface and a cut extending vertically to the tread surface without changing the shape in the depth direction.

Here, in order to improve the edge effect, it is effective to increase the number of sipes in the land portion. However, if the number of sipes in the land portion is increased too much, the land portion is subdivided and the land portion rigidity is increased. Decreases. As a result, while the snow performance is improved, the ground contact area of the land portion is decreased, and thus the dry performance and the wet performance may be deteriorated.
Therefore, in recent years, a three-dimensional sipe has been proposed in which the shape of the sipe is changed in the depth direction and the inner wall surfaces of the subdivided land portions are brought into contact with each other to suppress the collapse of the land portions (for example, patents). Reference 1).

JP 2008-49971 A

  However, when using a three-dimensional sipe, it is possible to ensure the dry performance and wet performance as described above, but the edge effect is reduced because the deformation of the land portion is suppressed, compared with two-dimensional sipe This time, snow performance tends to decrease.

  In this way, two-dimensional sipe and three-dimensional sipe are in a trade-off relationship, so it is difficult to improve all of snow performance, dry performance, and wet performance at the same time in the same land, and further improvement is eagerly desired. It had been.

  Accordingly, an object of the present invention is to provide a pneumatic tire that can realize snow performance, dry performance, and wet performance at a high level simultaneously in a single land portion in a pneumatic tire provided with a sipe in a land portion. There is.

The inventor has conducted extensive research to achieve the above-mentioned object, and as a result of the tire rotation, the deformation of the land portion subdivided by sipe is on the snow road surface and the dry road surface or the wet road surface (hereinafter referred to as “normal road surface”). I found a big difference. Specifically, when a vehicle equipped with a sipe-equipped tire on the land is run on a snowy road surface, the snow side that becomes the road surface is deformed, so the deformation of the land part subdivided by sipe is As shown to Fig.1 (a), it becomes a bending deformation which draws one convex toward the stepping side. On the other hand, when a vehicle equipped with the tire is run on a normal road surface, the land surface is constrained to the road surface, and the deformation of the land portion subdivided by sipe is shown in FIG. As shown in the figure, from the inside in the tire radial direction to the outside in the tire radial direction, after drawing a convex toward the stepping side, it becomes a bending deformation that passes through the inflection point and this time, the convex toward the kicking side. I found
The inventor pays attention to the difference in bending deformation in the depth direction of the tire described above, and appropriately sets the sipe shape according to the depth position of the sipe. Obtaining knowledge that performance, that is, snow performance, dry performance, and wet performance can be secured, the present invention has been completed.

That is, the gist of the present invention is as follows.
(1) A pneumatic tire having a land portion in a tread portion and provided with a sipe extending in the tire width direction with an amplitude in the tire circumferential direction on the land portion,
The sipe is in the depth direction from the land surface toward the inside in the tire radial direction,
A land surface side portion bent from the land surface toward the tire circumferential direction;
Air having a land portion bottom side portion bent in a direction different from the land portion surface side portion or bent in a tire circumferential direction with a displacement different from the displacement of the land portion surface side portion. Enter tire.

  According to the pneumatic tire of the present invention, an edge component (in the tire width direction and the tire circumferential direction) is formed on the surface (tread surface) in contact with the road surface. It can be demonstrated. Moreover, since the sipe near the land surface is bent in the depth direction in the direction (tire circumferential direction) perpendicular to the longitudinal direction of the sipe (tire width direction), the sipe opens and the edge is snow on the road surface. When digging up, the amount of intrusion into the snow in the land increases and snow performance can be further improved. On the other hand, in the depth region (land portion bottom side portion) on the inner side in the tire radial direction from the vicinity of the land surface, the inner wall surfaces of the land portion subdivided by sipe are in contact with each other, and the land portion collapses adjacent to each other. Will be suppressed. As a result, it is possible to ensure a sufficient ground contact area in the land and ensure good dry performance and wet performance.

(2) The pneumatic tire according to (1), wherein the sipe depth at both ends of the sipe in the sipe width direction is shallower than the sipe depth in the center of the sipe width direction.

According to such a configuration, since the land portion rigidity is ensured, it is possible to suppress the falling of the land portion and further improve the dry performance and the wet performance.
In the present invention, “sipe width direction” refers to the longitudinal direction of the sipe, and “both ends in the sipe width direction” refers to both ends in the longitudinal direction of the sipe.

(3) The pneumatic tire according to (1) or (2), wherein the depth of the land surface side portion is 20 to 40% of the maximum depth of the sipe.

  According to such a configuration, the snow performance is improved by sipe near the land surface, and the dry performance and wet performance are improved by suppressing the falling of the land in the depth region inside the tire radial direction from the vicinity of the land surface. Can be achieved most efficiently.

(4) The pneumatic tire according to any one of (1) to (3), wherein the land surface side portion has one bending point.

  By adopting such a configuration, the amount of penetration of the land portion into the snow and the amount of digging are increased, and the snow performance can be further improved by the edge effect.

(5) The sipe has a vertical part extending from the land surface toward the inside in the tire radial direction at at least one end in the sipe width direction. The pneumatic tire according to any one of the above.

With such a configuration, the tire vulcanization mold used for forming the sipe can be easily manufactured, and as a result, the tire can be easily manufactured.
In the present invention, “extends inward in the tire radial direction” means that the vertical portion extends at an angle of 10 ° or less with respect to a direction parallel to the tire radial direction.

(6) The pneumatic tire according to (5), wherein a sipe depth of the vertical portion is shallower than a sipe depth at a sipe width direction center.

  According to such a configuration, it is possible to secure the land portion rigidity to further improve the dry performance and the wet performance, and to sufficiently improve the snow performance.

  According to the present invention, in a pneumatic tire having a sipe in a land portion, a pneumatic tire capable of simultaneously realizing all of snow performance, dry performance, and wet performance in a single land portion at a high level is provided. It becomes possible.

(A) is a figure showing the deformation | transformation state of the land part subdivided by the sipe at the time of driving | running | working on a snowy road surface, (b) is a figure of the land part subdivided by the sipe at the time of driving | running | working on a normal road surface. It is a figure showing a deformation | transformation state. It is a partial expanded view of the tread part of the pneumatic tire according to the present invention. It is a cross-sectional perspective view which shows an example of the state of the depth direction of the sipe 3a shown in FIG. It is an arrow line view at the time of cut | disconnecting the land part 2 shown in FIG.2 and FIG.3 in the tire circumferential direction by the straight line AA. It is a cross-sectional perspective view which shows the other example of the state of the depth direction of the sipe 3a shown in FIG. It is an arrow line view at the time of cut | disconnecting the land part 2 shown in FIG.2 and FIG.5 in the tire circumferential direction by the straight line AA. In the land part 2, it is a figure which shows the example of arrangement | positioning from which the bending direction of a land part surface side part differs between sipes. It is a cross-sectional perspective view which shows the sipe of a conventional example tire. It is a cross-sectional perspective view which shows the sipe of a comparative example tire. (A)-(f) is a figure explaining the planar view shape and position of a sipe in each depth direction position about the sipe 3a shown in FIG. It is a cross-sectional perspective view which shows the modification of the sipe which shows a cross-sectional perspective view in FIG. It is a cross-sectional perspective view which shows the modification of the sipe which shows a cross-sectional perspective view in FIG.

  Hereinafter, a pneumatic tire according to the present invention will be described in detail with reference to the drawings. FIG. 1 (a) is a diagram showing a deformed state of a land portion subdivided by sipe when traveling on a snowy road surface, and FIG. 1 (b) is subdivided by sipe when traveling on a normal road surface. It is a figure showing the deformation | transformation state of the land part. FIG. 2 is a partial development view of a tread portion of the pneumatic tire according to the present invention. FIG. 3 is a cross-sectional perspective view showing an example of a state in the depth direction of the sipe 3a shown in FIG. FIG. 4 is an arrow view when the land portion 2 shown in FIGS. 2 and 3 is cut in the tire circumferential direction along a straight line AA. In FIG. 4, sipes are not shown. FIG. 5 is a cross-sectional perspective view showing another example of the depth direction of the sipe 3a shown in FIG. FIG. 6 is an arrow view when the land portion 2 shown in FIGS. 2 and 5 is cut in the tire circumferential direction by a straight line AA. In FIG. 6, sipes are not shown. FIG. 7 is a diagram illustrating an arrangement example in which the bending direction of the land portion surface side portion is different between sipes in the land portion 2. FIG. 8 is a cross-sectional perspective view showing a sipe of a conventional tire. FIG. 9 is a cross-sectional perspective view showing a sipe of a comparative tire. FIG. 10 is a diagram for explaining the shape and position of the sipe in plan view at each position in the depth direction with respect to the sipe 3a shown in FIGS. Further, FIG. 11 is a sectional perspective view showing a modified example of the sipe whose sectional perspective view is shown in FIG. 3, and FIG. 12 is a sectional perspective view showing a modified example of the sipe whose sectional perspective view is shown in FIG. is there.

FIG. 2 is a partial development view of a tread portion 1 of a pneumatic tire (hereinafter referred to as “tire”) according to the present invention.
The tread portion 1 has a block-shaped or rib-shaped land portion 2. In the illustrated example, the block-shaped land portion 2 is formed by a circumferential groove extending in the tire circumferential direction (Y direction shown in FIG. 2) and a transverse groove extending in the tire width direction (X direction shown in FIG. 2) intersecting with the circumferential groove. A plurality of sections are formed, and four block rows are formed in the tire width direction.
The land portion 2 is provided with a sipe 3 extending in the tire width direction, and in the illustrated example, four sipes 3a to 3d, each of which has an amplitude in the tire circumferential direction as shown in FIG. A zigzag shape is drawn. Note that the “sipe extending in the tire width direction” herein includes a sipe extending at an angle of 60 ° or less with respect to a direction parallel to the tire width direction. Therefore, in the example shown in FIG. 2, the sipe extends in a direction that is completely parallel to the tire width direction, that is, a direction orthogonal to the tire circumferential direction. A sipe may be inclined with the line CL as a boundary in a land portion in the right side area of the paper and sloping upward in the land area in the left side area of the paper.
In FIG. 2, the sipe 3 has a zigzag shape, but the shape of the sipe 3 may be a shape that extends in the tire width direction with an amplitude in the tire circumferential direction, and may be, for example, a wave shape. Moreover, although the four sipes 3a-3d are provided with respect to the one land part 2, the number of sipes may be 1-3 or five or more. Further, in the illustrated example, both ends of the sipe 3 are open to the circumferential groove or tread end, but the sipe 3 may be terminated in the land portion 2.

  In the tire according to the present invention, the sipe 3 is bent from the land surface S toward the tire circumferential direction in the depth direction from the land surface S toward the inner side in the tire radial direction. It is important to have a portion and a land bottom side portion that bends in a direction different from the land surface side portion or bends in the tire circumferential direction with a displacement different from the displacement of the land surface side portion. . In the present specification, “bend in the tire circumferential direction (or tire width direction)” includes a case in which it is bent in a direction inclined with respect to the tire circumferential direction (or tire width direction). I mean.

Here, FIGS. 1 (a) and 1 (b) show the deformation of the land portion when the vehicle equipped with the tire having the land portion 20 formed with the sipe 30 is run on the snow road surface and the normal road surface. Will be described again. The land portion 20 is subdivided into small land portions 20 a by the sipe 30.
First, when the vehicle is driven on a snowy road surface, the snow side which is the road surface is deformed, so that the small land portion 20a subdivided by sipe is directed toward the stepping side as shown in FIG. 1 (a). It becomes a simple bending deformation that draws one convex. On the other hand, when the vehicle is driven on a normal road surface, the surface of the land portion is restrained by the road surface without being deformed on the road surface side. Then, as shown in FIG. 1B, the small land portion 20a subdivided by the sipe is deformed after a convex is drawn on the stepping side when the deformation from the inner side to the outer side in the tire radial direction is seen. After the bending point, this time it becomes a double bending deformation that draws a convex toward the kicking side. Thus, the deformation form of the small land portion 20a subdivided by sipes is completely different depending on the road surface condition.

Therefore, in the present invention, considering the difference in bending deformation of the above-mentioned small land portion, which differs depending on the road surface state, by appropriately arranging the sipe shape according to the depth position, various road surface states can be achieved within one land portion. This is to provide a pneumatic tire that can be used.
Specifically, when running on a snowy road surface in which the deformation of the small land portion 20a is a simple bending deformation (FIG. 1A), the snow performance is effective in the vicinity of the land surface surface where the contact frequency with the road surface is high during tire rotation. Place sipe. It is because the corner | angular part 4 of the subdivided small land part 20a penetrates into snow by arrange | positioning the sipe concerning a land surface vicinity area | region, and an edge can act effectively. On the other hand, when traveling on a normal road surface where the deformation of the small land portion 20a is double bending deformation, the small land portion 20a is prevented from falling into the central region in the depth direction of the land portion, which is inside the tire radial direction from the vicinity of the land surface. Place a working sipe. Since the inner walls of the subdivided small land portions 20a are in contact with each other in the central region 5 in the depth direction of the land portion, the collapse of the small land portion 20a is particularly effective by arranging sipes for the region. Is suppressed. As a result, it is possible to secure a ground contact area of the entire land portion 20 during normal road running and improve traction performance and braking performance.

  Hereinafter, the characteristic configuration of the sipe of the present invention in consideration of the bending deformation described above will be specifically described with reference to some embodiments.

<First embodiment>
FIG. 3 is a cross-sectional perspective view showing an example of a state in the depth direction of the sipe 3a shown in FIG.
As described above, the shape of the sipe 3a in the land surface S is a zigzag shape having an amplitude f. And, in the depth direction (Z direction) from the land surface S toward the inside in the tire radial direction, it is bent and extended while being displaced in the tire circumferential direction (Y direction) and the tire width direction (X direction). At this time, the sipe 3a extends in the tire radial direction while maintaining the same shape as the zigzag shape (amplitude shape) on the land surface S.
FIG. 3 shows a cross-sectional state of the sipe 3a among the plurality of sipe 3, but in the illustrated example, the sipe 3a to 3d are provided in parallel to each other, and all have the same sipe shape. It is.

  Next, FIG. 4 is an arrow view when the land portion 2 shown in FIGS. 2 and 3 is cut in the tire circumferential direction along a straight line AA. More specifically, as shown in FIG. 2, the intersection of the center line L of the amplitude of the zigzag sipe 3a on the land surface S and the sipe 3a (that is, the position of the amplitude 0 of the sipe 3a) is defined as a point P. Shows an example of a cross-sectional view of the land portion 2 when the land portion 2 is cut by a plane perpendicular to the land surface S through the point P and perpendicular to the center line L. It is a thing. Here, the center line L of the amplitude of the sipe 3a refers to a virtual line that represents an average position in the tire circumferential direction of the sipe 3a that is displaced in the tire circumferential direction. That is, it refers to a tire circumferential direction equal dividing line between two straight lines connecting the maximum position in the tire circumferential direction of the sipe 3a (the tire circumferential direction outermost position) in the tire width direction.

  The land portion 2 is subdivided into five small land portions 2a by four sipes 3a to 3d. Here, in FIG. 4, when the land portion 2 is cut along a plane parallel to the land surface S, the reference sign Q indicates the center line of the amplitude of the sipe 3 that draws a zigzag shape on the cross section in the tire radial direction. The connected surface (hereinafter referred to as the sipe center plane Q) is shown. That is, the trajectory of the center line of the amplitude of the sipe 3 extending in the tire radial direction while maintaining the zigzag shape on the land surface S is shown on the AA cross section. A reference symbol R indicated by a dotted line indicates a sipe inflection point, that is, the maximum amplitude position of the sipe when the sipe 3a to 3d are seen through the AA cross section of the land portion 2. Therefore, in the sipe 3 having the amplitude f, the distance from the sipe center plane Q to the dotted line R is f.

And as above-mentioned, in the tire of this invention, the sipe 3a is a land part surface side part bent from the land part surface S toward the tire circumferential direction in the depth direction which goes to the tire radial direction inner side from the land part surface S. It is characterized by having 3a ₁ . In other words, in the cross section of FIG. 4, the center plane Q is displaced so as to protrude rightward or leftward on the paper surface in the vicinity of the land surface (in the illustrated example, rightward on the paper surface). It is characterized by returning to the same position as the position in the tire circumferential direction.
As described above, the tire of the present invention not only has a sipe having a zigzag shape in plan view on the land surface S in the region near the land surface, but also in the longitudinal direction of the sipe (in the illustrated example, the tire). It has a sipe that bends in a direction orthogonal to the width direction (in the illustrated example, the tire circumferential direction). As a result, an edge component is formed on the land surface S and the traction performance in the contact area with the snow road surface is improved. In addition, the snow performance is also improved in the depth direction of the land portion. It becomes possible to make it. That is, according to the above configuration, when the sipe opens and the land portion digs up snow on the road surface, the amount of penetration of the land portion into the snow increases, and the contact area with the snow and the amount of digging increase. become. As a result, it is possible to further improve the snow performance in the vicinity of the land surface.

A tire Additionally the present invention, the sipes 3a, at the tire radial direction area inside the land portion surface portion 3a _1, land portion surface portion 3a ₁ and different directions, in the first embodiment, the tire width It has a land portion bottom side portion 3a ₂ bent and extending in the direction. In other words, in the cross section shown in FIG. 4, the sipe center plane Q is linear without being displaced in the left-right direction on the paper.
If it demonstrates in detail, the sipe 3a will change the planar view shape seen from the land part surface side as shown to Fig.10 (a)-(f) in the depth direction of the sipe 3a. Specifically, the sipe 3a shows the plan view shape of the sipe 3a at the land surface position in FIG. 10A, and the plan view shape of the sipe 3a at the position II shown in FIG. FIG. 10C shows the plan view shape of the sipe 3a at the position II-II shown in FIG. 3, and FIG. 10D shows the plan view shape of the sipe 3a at the position III-III shown in FIG. FIG. 10E shows a plan view shape of the sipe 3a at the position IV-IV shown in FIG. 3, and FIG. 10F shows a plan view shape of the sipe 3a at the position V-V shown in FIG. , Changes (bends) in the depth direction. In FIG. 10, a line P ′ indicates the position of a virtual plane extending in the tire radial direction through the center line L located on the surface of the land portion.
10 (a) to 10 (c), in the land surface side portion 3a ₁ , the sipe 3a is maintained in a planar view shape (zigzag shape) from the land surface side toward the inside in the tire radial direction, It can be seen that after displacement to one side in the tire circumferential direction (lower side in FIG. 10), the position returns to the original (same as the land surface) tire circumferential position. Further, from FIG. 10 (c) ~ (f), the land portion bottom part 3a _2, toward the land portion surface side in the tire radial direction inner side, the sipe 3a is maintained a plan view shape (zigzag shape) It can be seen that after returning to one side in the tire width direction (right side in FIG. 10), returning to the original position in the tire width direction is repeated. And in the land part bottom side part 3a ₂ , since the sipe 3a is displaced toward the tire width direction one side (right side in FIG. 10), without changing the position of a tire circumferential direction, in the cross section shown in FIG. The sipe center plane Q is linear without being displaced in the left-right direction on the paper.

  When a force is applied to the land portion 2 when traveling on a normal road surface, the small land portion 2a subdivided by the sipe is collapsed. In this case, as described above with reference to FIG. The small land portions will be in contact with each other in the central area. Therefore, at least in this region, the sipe 3a is bent in the tire width direction (that is, the sipe 3a is displaced in the tire width direction at the bottom portion of the land while maintaining the shape in plan view). The bent portions of the land portion 2a are engaged with each other, and the falling of the small land portion can be effectively suppressed. As a result, a sufficient contact area of the land portion is ensured, and it becomes possible to improve the traction performance and the brake performance when traveling on a normal road surface.

Further, as shown in FIG. 3, the sipe 3 preferably has a sipe depth at both ends in the sipe width direction that is shallower than a sipe depth at the center in the sipe width direction. If it demonstrates concretely using the sipe 3a shown in FIG. 3, in the sipe 3a extended in the tire width direction formed in the land part 2, at both ends of the sipe, from the land part surface S toward a tire radial inside, Only the land surface side portion 3a ₁ is formed. On the other hand, at the center of the sipe, from the land surface S toward the inside in the tire radial direction, not only the land surface side portion 3a ₁ but also the land portion bottom side portion on the tire radial direction inside of the land surface side portion 3a _1. 3a ₂ is formed.
As described above, when the sipe is provided in the land portion, the land portion is subdivided, so that the land portion rigidity is reduced as compared with the case where the sipe is not provided. Therefore, by providing sipes having shallow depths at both ends in the width direction of the land portion 2 as described above, the rigidity of the land portion is secured, the collapse of the land portion is suppressed, and the dry performance and wetness during normal road surface traveling are suppressed. The performance can be further improved. Moreover, since the land portion surface side portions 3a ₁ are provided at both ends in the width direction of the land portion, it is possible to simultaneously ensure snow performance when traveling on a snowy road surface.

The depth H1 of the land portion surface portion 3a ₁ is preferably 20 to 40% of the maximum depth H of the sipe, even more preferably 25 to 35%.
By arranging the land surface side portion 3a ₁ in such a range, the land portion easily penetrates into snow when traveling on a snowy road surface, so that the sipe function in the area near the land surface can be sufficiently exhibited. This is because the snow performance can be improved. On the other hand, as shown in FIG.1 (b), the small land parts subdivided by the sipe mutually contact in the center area of the land part in the depth direction at the time of a normal road surface driving | running | working. Therefore, by placing the land portion bottom side portion 3a ₂ in a region deeper than 20 to 40% of the maximum sipe depth H from the land surface S, the collapse of the land portion is sufficiently suppressed, and the dry performance and wetness are reduced. This is because the performance can be improved. Thus, by arranging the land portion surface side portion 3a ₁ in the above range, the functions of both the land portion surface side portion 3a ₁ and the land portion bottom side portion 3a ₂ can be exhibited most efficiently. Become.
The maximum sipe depth H can be 60 to 90% of the circumferential groove depth.

Further, in sipes 3a, land portion surface portion 3a _1, as shown in FIGS. 3 and 4, it is preferable to have one inflection point.
Thus, when the sipe 3a is greatly bent only once in the tire circumferential direction in the region near the land surface, the resistance to the road surface of the land surface side portion 3a ₁ penetrating into the snow increases. As a result, the amount of intrusion into the snow in the land and the amount of digging are increased, and it is possible to further improve the snow performance.

Further, as shown in FIG. 4, the sipe center plane Q of the land portion surface portion 3a _1, displacement m the tire circumferential direction between the starting point and the bending point on the land portion surface S is, land portion surface portion 3a ₁ It is preferably 0.2 to 0.4 times the distance (dimension) H1 in the depth direction.
By setting the degree of bending of the land portion surface side portion 3a ₁ within the above range, the amount of penetration of the small land portion 2a into snow and the amount of digging are increased. As a result, the snow performance can be further improved.

<Second embodiment>
FIG. 5 is a cross-sectional perspective view showing another example of the depth direction of the sipe 3a shown in FIG.
The sipe 3a has a zigzag shape having an amplitude f on the land surface S. And, in the depth direction (Z direction) from the land surface S toward the inside in the tire radial direction, it is bent and extended while being displaced in the tire circumferential direction (Y direction). At this time, the sipe 3a extends in the tire radial direction while maintaining the same shape as the zigzag shape on the land surface S.
FIG. 5 shows the cross-sectional state of the sipe 3a among the plurality of sipe 3 shown in FIG. 2, and in the illustrated example, the sipes 3a to 3d are provided in parallel to each other. Sipe with the same shape.

  Next, FIG. 6 shows an arrow view when the land portion 2 shown in FIGS. 2 and 5 is cut in the tire circumferential direction by a straight line AA. More specifically, as shown in FIG. 2, the land portion 2 when the land portion 2 is cut by a plane perpendicular to the land surface S through the point P and perpendicular to the center line L. It shows another example of the cross-sectional view.

In the tire of the present embodiment, the sipe 3a is bent from the land surface S to the tire circumferential direction in the depth direction from the land surface S to the inside in the tire radial direction (as in the first embodiment). It is characterized by having a land surface side portion 3a ₁ that is displaced). In other words, in the cross section shown in FIG. 6, the center plane Q is displaced so as to protrude rightward or leftward on the paper surface in the vicinity of the land surface (in the illustrated example, rightward on the paper surface). It is characterized in that it returns to the same position as the position in the tire circumferential direction.
According to this configuration, as described above, the traction performance on snowy roads can be improved, and the amount of intrusion into the snow and the amount of digging can be increased, so that the snow performance is further improved. be able to.

Then, in the second embodiment, the sipe 3a is at the tire radial direction area inside the land portion surface portion 3a _1, tire circumferential with a different displacement n the displacement m of the land portion surface portion 3a ₁ It has the land part bottom side part 3a ₂ bent in the direction, and this point is different from the first embodiment. In other words, in the cross section shown in FIG. 6, the sipe center plane Q in the tire radial direction inner region from the land surface vicinity region is bent in the left-right direction on the paper surface in the same manner as the land surface side portion 3 a _1. As shown, the displacement n of the land bottom side portion 3a _{2 in} the tire circumferential direction is different from the displacement m of the land surface side portion 3a _{1 in} the tire circumferential direction. The “displacement” is equal to twice the amplitude of the sipe center plane Q in the tire circumferential cross section (that is, the vibration width).
According to such a configuration, when the small land portion 2a falls, the bent portions engage with each other in a region where the small land portions contact each other, so that the fall of the small land portion can be effectively suppressed. Further, both the land portion surface side portion 3a ₁ and the land portion bottom side portion 3a ₂ are bent in the tire circumferential direction, and the displacements thereof are made different to achieve both performance on the snow road surface and the normal road surface. Can do. As a result, it is possible to secure a sufficient land area on the land and improve traction performance and braking performance during normal road running.

Incidentally, the displacement n in the circumferential direction of the tire land portion bottom part 3a ₂ is greater than the displacement m in the circumferential direction of the tire land portion surface portion 3a ₁ (m <n) is preferable. This is because the degree of meshing between the small land portions 2a, that is, the support effect between the small land portions can be increased.

  Other configurations and other configurations of the sipe 3 in the second embodiment are the same as the configurations described in the first embodiment, and thus description thereof is omitted.

In the first embodiment and the second embodiment, as shown in FIGS. 4 and 6, in the land portion 2, the bending directions of the land surface side portions 3 a ₁ of the plurality of sipes 3 are all the same direction. Although an arrangement example has been shown, it is important for the tire of the present invention to have the above-described sipe shape. For example, as shown in FIG. 7, the bending direction of the land surface side portion 3 a _{1 in} the land portion 2. May be arranged differently.

In the first embodiment and the second embodiment, as shown in FIGS. 3 and 5 for the sipe 3a, the sipe depth at both ends in the sipe width direction is made shallower than the sipe depth at the center in the sipe width direction, At both ends in the direction, only the land surface side portion 3a ₁ was formed from the land surface S toward the inside in the tire radial direction. However, in the tire of the present invention, a vertical portion extending from the land surface S toward the inside in the tire radial direction may be formed at at least one end in the sipe width direction. In addition, the angle which a perpendicular | vertical part and the land part surface S comprise can be 80-90 degrees.
Specifically, FIG. 11 shows a modification of a sipe whose sectional perspective view is shown in FIG. 3, and FIG. 12 shows a modification of a sipe whose sectional perspective view is shown in FIG. The vertical portions 6 may be formed at both ends in the width direction of the sipe, and the vertical portions 6 may be opened at the circumferential grooves or tread ends. If the vertical portion 6 is formed, when forming a sipe using a sipe forming blade provided on the inner peripheral surface (tread molding surface) of the vulcanization mold, the sipe is formed on the inner peripheral surface of the vulcanization mold. It is because arrangement | positioning (planting) of the blade for this can be performed easily.
In addition, from the viewpoint of further improving dry performance and wet performance by ensuring the rigidity of the land portion and sufficiently improving snow performance, the depth of the vertical portion 6 should be shallower than the sipe depth in the center of the sipe width direction. Is preferred. Further, from the viewpoint of ensuring sufficient snow performance while facilitating the manufacture of the vulcanization mold, the width of the vertical portion 6 in the sipe extending direction is preferably 0.1 m to 0.5 mm. Furthermore, from the viewpoint of sufficiently ensuring snow performance, the tire of the present invention has a vertical portion 6 having a sipe depth shallower than the sipe width direction center and a sipe width direction center, as shown in FIGS. Further, it is preferable that the sipe depth is shallow and the land portion surface side portion 3a ₁ is provided at both ends in the sipe width direction.

  Next, inventive tires 1 to 6 according to the present invention, conventional tires according to the prior art, and comparative tires were prototyped, and the snow performance, dry performance, and wet performance of each tire were evaluated.

The invention example tire 1 has a tread pattern shown in FIG. 2 having a size of 195 / 65R15, an applied rim 6J × 15, an applied internal pressure of 200 kPa, a sipe cross section shown in FIG. 3, and a sipe center plane Q shown in FIG. 1 is a radial tire for a passenger car according to the first embodiment. Each specification is as shown in Table 1 below.
The invention example tire 2 is a radial tire for a passenger car according to the second embodiment, including a land portion having the tread pattern shown in FIG. 2, the sipe cross section shown in FIG. 5, and the sipe center plane Q shown in FIG. These are the same as those of the tire 1 of the invention except that the respective specifications are as shown in Table 1 below.
The invention example tire 3 includes a land portion in which sipes are arranged so that the bending direction of the land portion surface side portions of the sipes 3a and 3b is opposite to the bending direction of the land portion surface side portions of the sipes 3c and 3d. This is a radial tire for passenger cars, and is the same as the tire 1 of the invention except that each specification is as shown in Table 1 below.
The invention example tire 4 is a radial tire for passenger cars having a sipe whose sipe depth at the both ends of the sipe width direction is the same as the sipe depth at the center of the sipe width direction. Each specification is shown in Table 1 below. It is the same as that of the invention example tire 1 except being as shown.
The invention example tire 5 is a radial tire for a passenger car including a sipe in which the depth H1 of the land surface side portion 3a ₁ is less than 20% of the maximum sipe depth H. The invention example tire 6 is a land tire. A radial tire for a passenger car having a sipe in which the depth H1 of the part surface side portion 3a ₁ is greater than 40% of the maximum sipe depth H, except that each specification is as shown in Table 1 below. These are the same as those of the tire 1 of the invention.

On the other hand, as shown in FIG. 8, the conventional example tire has a zigzag shape extending in the tire width direction with an amplitude in the tire circumferential direction and a land portion having a two-dimensional sipe extending linearly in the tire radial direction. A radial tire for a passenger car equipped with
Furthermore, as shown in FIG. 9, the comparative example tire has a zigzag shape that extends in the tire width direction with an amplitude in the tire circumferential direction, in the tire 1 of the invention example, in the tire 1 of the invention, located in the region of the depth H1 from the land surface. This is a radial tire for a passenger car having a two-dimensional sipe having a linear shape extending in the tire radial direction.

  The inventive tires 1 to 6, the conventional tires, and the comparative tires were each mounted on a vehicle and subjected to various evaluation tests. At this time, the invention example tires 1, 2, 4 to 6 and the comparative example tires are such that the bending direction of the sipe in the tire circumferential direction (the direction in which the bending point is located) is the kicking side direction of the land portion. Tires were mounted on the vehicle.

Snow performance was evaluated by performing an on-snow acceleration test in which the vehicle was installed on a snowy road surface, the accelerator was fully opened from the stationary state of the vehicle, and the time (acceleration time) until traveling 50 m was measured. Wet performance was evaluated by performing a wet braking test in which the vehicle was placed on a wet road surface and the control distance until the vehicle became stationary when full braking was applied from the initial speed of 80 km / h. The dry performance was evaluated by performing a dry braking test in which the vehicle was placed on a dry road surface and the control distance until the vehicle became stationary when full braking was applied from the initial speed of 100 km / h.
The results are shown in Table 2. Both are values expressed as indices with the measured value of the conventional tire as 100 (reference), and the larger the value, the better each performance.

From the results in Table 2, it was found that all of the inventive example tires 1 to 6 were significantly improved in snow performance, wet performance, and dry performance as compared with the conventional tire.
Moreover, it turned out that the invention example tire 1 can improve not only wet performance and dry performance but also snow performance at the same time as compared with the comparative example tire.

  According to the present invention, in a pneumatic tire provided with a sipe in a land portion, a pneumatic tire capable of simultaneously realizing all of snow performance, dry performance, and wet performance in a single land portion at a high level is provided. It became possible.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Land part 2a Small land part 3 Sipe 3a ₁ Land part surface side part 3a ₂ Land part bottom side part 4 Corner part of small land part 2a 5 Depth center area 6 Vertical part P Land part Intersection point of center line L on surface S and sipe 3 Q Sipe center plane R Maximum amplitude position of sipe S Land surface L Center line of amplitude of sipe f Maximum amplitude m Displacement of land surface side portion 3a ₁ in tire circumferential direction n Tire circumferential direction displacement of the land bottom side portion 3a ₂

Claims (6)

In a pneumatic tire having a land portion in a tread portion and provided with a sipe extending in the tire width direction with an amplitude in the tire circumferential direction on the land portion,
The sipe is in the depth direction from the land surface toward the inside in the tire radial direction,
A land surface side portion bent from the land surface toward the tire circumferential direction;
Air having a land portion bottom side portion bent in a direction different from the land portion surface side portion or bent in a tire circumferential direction with a displacement different from the displacement of the land portion surface side portion. Enter tire. 2. The pneumatic tire according to claim 1, wherein a sipe depth at both ends of the sipe in the sipe width direction is shallower than a sipe depth at a center in the sipe width direction. 3. The pneumatic tire according to claim 1, wherein a depth of the land surface side portion is 20 to 40% of a maximum depth of the sipe. The pneumatic tire according to any one of claims 1 to 3, wherein the land surface side portion has one bending point. The said sipe has a perpendicular | vertical part extended toward the tire radial inside from the said land part surface in the at least one edge part of a sipe width direction, The Claim 1 characterized by the above-mentioned. Pneumatic tires. The pneumatic tire according to claim 5, wherein the sipe depth of the vertical portion is shallower than the sipe depth in the center of the sipe width direction.

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