JP5956139B2 - Pneumatic tire - Google Patents

Description

  The present invention includes a plurality of rib-like land portions defined by circumferential grooves and / or block-shaped land portions defined by transverse grooves intersecting the circumferential grooves and the circumferential grooves. The present invention relates to a pneumatic tire provided with a plurality of sipes on a land portion.

  Conventionally, in a tire for running on a snowy road surface, in order to improve braking force 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. A sipe is formed and an edge component is provided. As such a sipe, there is known a two-dimensional sipe that is zigzag or corrugated on the tread surface and that has a notch perpendicular to the tread surface without changing its 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 decreases. To do. 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, Patent Document 1 proposes a three-dimensional sipe in which the shape of the sipe is changed even 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. .

  However, when using a three-dimensional sipe, it is possible to ensure 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. Thus, since the two-dimensional sipe and the three-dimensional sipe are in a trade-off relationship, it has been difficult to improve all of the snow performance, the dry performance, and the wet performance at the same time.

  On the other hand, Patent Document 2 proposes arranging both a two-dimensional sipe and a three-dimensional sipe in the tread portion. According to such a configuration, it is shown that the entire performance of snow performance, dry performance, and wet performance can be ensured in the entire tread portion.

JP 2008-49971 A Japanese Patent No. 4677498

  However, in recent years, further improvement has been eagerly desired to provide a pneumatic tire that simultaneously realizes snow performance, dry performance, and wet performance at a high level.

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

  The inventor has conducted extensive research to achieve the above 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 on the dry road surface or wet road surface (hereinafter referred to as a normal road surface). ) I found a big difference in the above. Then, it has been found that various shapes, that is, snow performance, dry performance, and wet performance can be simultaneously secured in one land portion by devising the sipe shape in consideration of the difference in the land portion deformation. In addition, the inventor has found that the performance of the pneumatic tire as a whole can be further improved by adding a device for appropriately arranging the land portion where such a sipe is disposed in the tread portion. The invention has been completed.

That is, the gist of the present invention is as follows.
(1) The tread portion includes a plurality of rib-like land portions defined by circumferential grooves and / or block-shaped land portions defined by lateral grooves intersecting the circumferential grooves and the circumferential grooves. In the pneumatic tire provided with a plurality of sipes in the land portion,
The sipe extends in the tire width direction with an amplitude in the tire circumferential direction, and bends in the tire circumferential direction with the land surface as a bending start position in the depth direction from the land surface to the inside in the tire radial direction. a land portion surface portion, and a land portion bottom portion that is bent toward the tire circumferential direction with a different displacement from the displacement of the land portion surface portion,
The displacement of the land portion bottom side portion in the tire circumferential direction is larger than the displacement of the land portion surface side portion in the tire circumferential direction,
The bending direction toward the tire circumferential direction of each land portion surface side portion of the plurality of sipes is in the same land portion continuous in the circumferential direction and in the row of the same land portion arranged in the circumferential direction. A pneumatic tire characterized by being all in the same direction.

  According to the pneumatic tire of the present invention, it is possible to simultaneously realize all of snow performance, dry performance, and wet performance at a high level.

(2) The bending direction of the land portion surface side portion of the sipe of the shoulder side land portion on the tread end side, and the land portion surface side of the sipe of the center side land portion located on the tire equator side from the shoulder side land portion The pneumatic tire according to (1), wherein the bending directions of the portions are different directions.

  According to such a configuration, it is possible to more effectively improve the performance that is particularly desired to be improved among the snow performance, the dry performance, and the wet performance, by appropriately setting and using the rotation direction of the tire. In particular, it is possible to further improve the snow performance at the center side land portion and the dry performance and wet performance at the shoulder side land portion.

(3) The bending direction of the land portion surface side portion of the sipe of the shoulder side land portion located on the tread end side, and the land portion surface side of the sipe of the center side land portion located on the tire equator side from the shoulder side land portion. The pneumatic tire according to (1), wherein the bending direction of the portion is the same direction.

According to such a configuration, since the bending direction of the land portion surface side portion of the sipe is the same in the entire region of the tread portion, among the snow performance or the wet performance and the dry performance, the performance to be particularly improved is improved over the entire tread portion. Can be ensured over the entire range.
(4) In the sipe, the sipe depth at both ends of the sipe width direction is shallower than the sipe depth at the center of the sipe width direction.
The pneumatic tire according to claim 1.

(5) In a pneumatic tire having a plurality of block-shaped land portions partitioned by a circumferential groove and a transverse groove intersecting the circumferential groove in the tread portion, and having a plurality of sipes on the land portion,
The sipe extends in the tire width direction with an amplitude in the tire circumferential direction, and bends in the tire circumferential direction with the land surface as a bending start position in the depth direction from the land surface to the inside in the tire radial direction. a land portion surface portion, and a land portion bottom portion that is bent toward the tire circumferential direction with a different displacement from the displacement of the land portion surface portion,
The displacement of the land portion bottom side portion in the tire circumferential direction is larger than the displacement of the land portion surface side portion in the tire circumferential direction,
The bending direction toward the tire circumferential direction of each land portion surface side portion of the plurality of sipes is opposite to each other in the tire circumferential direction one side region and the tire circumferential direction other side region in the same land portion. A pneumatic tire characterized by being.

  According to the pneumatic tire of the present invention, it is possible to simultaneously realize all of snow performance, dry performance, and wet performance at a high level.

(6) The pneumatic tire according to (5) , wherein a land portion provided with the sipe is disposed over the entire tread portion.

According to such a configuration, the land portions having sipes in the same land portion where the bending directions of the land surface side portions of the sipe are opposite to each other are arranged in the entire region of the tread portion. In addition, it is possible to ensure snow performance, wet performance, and dry performance.
(7) In the sipe, the sipe depth at both ends of the sipe width direction is shallower than the sipe depth at the center of the sipe width direction.
The pneumatic tire according to claim 5.

  ADVANTAGE OF THE INVENTION According to this invention, in the pneumatic tire which provided the sipe in the land part, it becomes possible to provide the pneumatic tire which can implement | achieve all of snow performance, dry performance, and wet performance simultaneously with a high dimension.

It is a partial expanded view of a tread part of an example of a pneumatic tire according to the present invention. (A) is a figure showing the deformation | transformation state of the land part subdivided by the sipe at the time of snowy road surface driving | running | working, (b) is the deformation state of the land part subdivided by the sipe at the time of normal road surface driving | running | working. FIG. It is a cross-sectional perspective view which shows an example of the state of the depth direction of the sipe 5a shown in FIG. It is arrow sectional drawing at the time of cut | disconnecting the land part 2 shown in FIG.1 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 5a shown in FIG. It is arrow sectional drawing at the time of cut | disconnecting the land part 2 shown in FIG.1 and FIG.5 in the tire circumferential direction by the straight line AA. It is a partial expanded view of a tread part of an example of a pneumatic tire according to the present invention. (A) is arrow sectional drawing at the time of cut | disconnecting the land part 2B shown in FIG. 7 in the tire circumferential direction by the straight line BB. (B) is arrow sectional drawing at the time of cut | disconnecting the land part 2A shown in FIG. 7 in the tire circumferential direction by the straight line CC. (A) is arrow sectional drawing at the time of cut | disconnecting the land part 2B shown in FIG. 7 in the tire circumferential direction by the straight line BB. (B) is arrow sectional drawing at the time of cut | disconnecting the land part 2A shown in FIG. 7 in the tire circumferential direction by the straight line CC. (A) is arrow sectional drawing at the time of cut | disconnecting the land part 2B shown in FIG. 7 in the tire circumferential direction by the straight line BB. (B) is arrow sectional drawing at the time of cut | disconnecting the land part 2A shown in FIG. 7 in the tire circumferential direction by the straight line CC. It is arrow sectional drawing at the time of cut | disconnecting the land part 2 shown in FIG. 7 in a tire circumferential direction by the straight line BB. It is arrow sectional drawing at the time of cut | disconnecting the land part 2 shown in FIG. 7 in the tire circumferential direction by the straight line CC. It is a figure which shows the conventional two-dimensional sipe and three-dimensional sipe provided in the land part of a conventional example tire.

  Hereinafter, a pneumatic tire according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a partial development view of a tread portion 1 of an example of a pneumatic tire (hereinafter referred to as “tire”) according to the present invention.
The tread portion 1 has a rib-like or block-like land portion 2. Here, the block-shaped land portion 2 is formed by a circumferential groove 3 that extends in the tire circumferential direction (Y direction shown in FIG. 1) and a lateral groove 4 that intersects this and extends in the tire width direction (X direction shown in FIG. 1). A plurality of sections are formed, and these block-like land portions 2 are arranged in the tire circumferential direction, thereby forming four rows of land portion rows in the tire width direction.
In addition, although the block-shaped land part divided by the horizontal groove 4 is shown in the example of illustration, the land part 2 may be a rib which is formed only by the circumferential groove 3 and is continuous in the tire circumferential direction. .
In addition, the circumferential groove 3 is linear in the illustrated example, but may be non-linear such as zigzag, sawtooth, or wave.

The land portion 2 is provided with a plurality of sipes 5 extending in the tire width direction, here, four sipes 5a to 5d.
And each of these sipes 5a-5d is drawing the zigzag shape with the amplitude f of a tire circumferential direction, as shown in FIG. Note that the sipe extending in the tire width direction herein includes a sipe extending from the tire width direction in a range of ± 60 ° with respect to the tire circumferential direction. Accordingly, in the illustrated example, each of the sipes 5a to 5d extends as a whole in a direction completely parallel to the tire width direction, that is, in a direction perpendicular to the tire circumferential direction. The sipe may be inclined so as to rise to the right shoulder in the land portion in the area on the right side of the paper, and tilted to rise in the left shoulder in the land portion in the area on the left side of the paper.
In the illustrated example, the sipe 5 has a zigzag shape. However, the shape of the sipe 5 may be a shape that extends in the tire width direction with an amplitude in the circumferential direction, and may be, for example, a wave shape. Moreover, although the example which provided the four sipes 5a-5d with respect to one land part 2 is shown, the number of the sipes 5 should just be two or more. Further, in the illustrated example, the sipe 5 opens at both ends of the land portion 2, but at least one end of the sipe 5 may be terminated in the land portion 2.

  In addition, the sipe 5 said by this invention means the notch of the opening width 0.3-1.0mm in the non-grounding which at least one part of the groove wall of a sipe closes at the time of the earth | ground part 2 grounding.

In the tire of the present invention, first, in the depth direction from the land surface S to the inside in the tire radial direction, the sipe 5 bends in the tire circumferential direction with the land surface S as the bending start position. a land portion surface portion, possess a land portion bottom portion that is bent toward the tire circumferential direction with a different displacement from the displacement of the land portion surface portion, the tire circumferential direction of the該陸portion bottom portion It is important that the displacement of the sipe is larger than the displacement of the land surface side portion in the tire circumferential direction .

Here, FIGS. 2A and 2B show the deformation state of the land portion when the vehicle equipped with the tire having the land portion 20 formed with the sipe 50 is run on the snow road surface and the normal road surface. It explains using. The land portion 20 is subdivided into small land portions 20 a by the sipes 50.
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. 2 (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, when the deformation state from the inner side to the outer side in the tire radial direction is seen, the small land portion 20a subdivided by the sipe changes after the convex is drawn on the stepping side as shown in FIG. 2 (b). After the bending point, this time it becomes a double bending deformation that draws a convex toward the kicking side. Thus, the deformation state of the small land portion 20a subdivided by sipe is completely different depending on the road surface state.

Therefore, in the present invention, a pneumatic tire that can cope with various road surface conditions by considering the difference in bending deformation of the above-mentioned small land portion that differs depending on the road surface state, and appropriately arranging the sipe shape according to the depth position. It is intended to realize the provision of.
Specifically, when running on a snowy road surface where the deformation of the small land portion 20a is a simple bending deformation (FIG. 2 (a)), 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 6 of the subdivided small land part 20a penetrates into snow by arrange | positioning the sipe concerning a land part surface vicinity area, and can make an edge 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, a sipe that is effective in suppressing the collapse of the small land portion 20a is disposed in a region deeper in the tire radial direction than near the land surface. In other words, since the inner walls of the subdivided small land portions 20a are in contact with each other in the region 7, in particular, by disposing the sipes over the region, the collapse of the small land portions 20a is effectively suppressed. . As a result, it is possible to secure the ground contact area of the entire land portion 20 and improve the traction performance and the brake performance when dry and wet.

  Below, the characteristic structure of the sipe of the present invention in consideration of the bending deformation described above will be specifically described using two embodiments.

<First embodiment of Sipe>
FIG. 3 is a cross-sectional perspective view showing an example of the state of the sipe 5a shown in FIG. 1 in the depth direction.
As described above, the sipe 5a has a zigzag shape having an amplitude f on the land surface S. In the depth direction (Z direction) from the land surface S toward the inside in the tire radial direction, the tire is in the vicinity of the land surface. In a region deeper than that in the circumferential direction (Y direction), it is bent and extended while being displaced in the tire width direction (X direction). At this time, the sipe 5a is displaced while maintaining the same shape as the zigzag shape on the land surface S, and extends in the tire radial direction.
FIG. 3 shows the cross-sectional state of the sipe 5a among the plurality of sipes 5, and all the sipes 5 have the sipe shape described here. Here, the sipes 5a to 5d are provided in parallel to each other in the tire width direction and the tire radial direction, and are all the same sipes.

  Next, FIG. 4 is a cross-sectional view of the land portion 2 shown in FIGS. 1 and 3 taken along the line AA in the tire circumferential direction. More specifically, as shown in FIG. 1, the intersection of the center line L of the amplitude of the zigzag sipe 5a on the land surface S and the sipe 5a (that is, the position of the amplitude 0 of the sipe 5a) is defined as a point P. When the land portion 2 is cut by a plane perpendicular to the land surface S through the point P on the land surface S and perpendicular to the center line L, the land portion 2 An example of a sectional view is shown. Here, the center line L of the amplitude of the sipe 5a refers to a virtual line that represents the average position in the tire circumferential direction of the sipe 5a that oscillates in the tire circumferential direction on the land surface S.

  The land portion 2 is subdivided into five small land portions 2a by four sipes 5a to 5d. Here, in FIG. 4, reference numeral 8 denotes the amplitude center line of the sipe 5 that draws a zigzag shape on the cross section when the land portion 2 is cut in a plane parallel to the land surface S, in the tire radial direction. A connected surface (hereinafter referred to as a sipe center surface 8) is shown. That is, the trajectory of the center line of the amplitude of the sipe 5 extending in the tire radial direction while maintaining the zigzag shape on the land surface S is shown on the AA cross section. Reference numeral 9 indicated by a dotted line indicates a sipe bending point, that is, the maximum amplitude position of the sipe when the sipe 5a to 5d is seen through the AA cross section of the land portion 2. Therefore, in the sipe 5 having the amplitude f, the distance from the sipe center plane 8 to the dotted line 9 is f.

As described above, in the tire of the present invention, the sipe 5a bends in the tire circumferential direction with the land surface S as the bending start position in the depth direction from the land surface S toward the inside in the tire radial direction. It has a land portion surface side portion 5a ₁ . In other words, in the cross section of FIG. 4, the sipe center plane 8 starts to be displaced immediately from the land surface S, and in the region near the land surface rightward or leftward (in the illustrated example, rightward on the paper). It is characterized by being displaced so as to be convex and returning to the same position as the tire circumferential direction position on the land surface S.
Thus, the tire of the present invention has not only a zigzag sipe on the land surface S in the region near the land surface, but also the sipe with the land surface S as the bending start position in the depth direction. A sipe that bends in a direction perpendicular to the longitudinal direction of As a result, an edge component is formed on the land surface S, and the braking force and traction performance in the contact area with the snow road surface are improved. Snow performance can be improved in the vicinity of the part surface. In other words, a surface that is inclined with respect to the snow road surface is formed at the time of ground contact, so that 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 contact with the snow The area and the amount of digging will be increased. As a result, it is possible to further improve the snow performance in the vicinity of the land surface.

On the other hand, in the tire radial direction area inside the land portion surface side portion 5a _1, sipes 5a may land portion surface side portion 5a ₁ and different directions, for example, as shown in the first embodiment, bent in the tire width direction It has a land portion bottom side portion 5a ₂ . In other words, in the cross section shown in FIG. 4, the sipe center surface 8 draws a straight line in the land bottom side portion 5a ₂ without being displaced in the left-right direction on the paper surface.

  When a force is applied to the land portion 2 during normal road surface traveling, the small land portion 2a subdivided by the sipe is collapsed. In this case, as described above with reference to FIG. In the area deeper than the area, the small land parts contact each other. Therefore, by bending the sipe 5a in the tire width direction at least in the region, the bent portions of the adjacent small land portions 2a can be engaged with each other, and the falling of the small land portions 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.

<Second embodiment of sipe>
FIG. 5 is a cross-sectional perspective view showing another example of the state of the sipe 5a shown in FIG. 1 in the depth direction.
As described above, the sipe 5a 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, the tire circumferential direction (Y direction). It bends and extends while being displaced. At this time, the sipe 5a is displaced while maintaining the same shape as the zigzag shape on the land surface S, and extends in the tire radial direction.
FIG. 5 shows the cross-sectional state of the sipe 5a among the plurality of sipes 5, and all the sipes 5 have the sipe shape described here. Here, the sipes 5a to 5d are provided in parallel to each other in the tire width direction and the tire radial direction, and are all the same sipes.

  Next, FIG. 6 shows an arrow view when the land portion 2 shown in FIGS. 1 and 5 is cut in the tire circumferential direction by a straight line AA. More specifically, as shown in FIG. 1, the land portion 2 is cut by a plane perpendicular to the land surface S so as to pass through the point P on the land surface S and to be orthogonal to the center line L. The other example of the cross-sectional view of the land portion 2 is shown.

Similar to the first embodiment, the sipe 5a includes a land portion surface side portion 5a ₁ that is bent from the land portion surface S toward the tire circumferential direction in the depth direction from the land portion surface S toward the inside in the tire radial direction. It is characterized by that. According to this configuration, as described above, the braking force and traction performance on snowy roads can be improved, and the amount of land penetration into the snow and the amount of digging are increased, further improving snow performance. Can be made.

And in the second embodiment, in the tire radial direction area inside the land portion surface side portion 5a _1, sipes 5a is in the tire circumferential direction with a different displacement n the displacement m of the land portion surface side portion 5a ₁ It has a land portion bottom side portion 5a ₂ that is bent, and this point is different from the first embodiment. In other words, in the cross section shown in FIG. 4, the sipe center surface 8 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 5 a _1. The displacement n of the land portion bottom side portion 5a _{2 in} the tire circumferential direction is different from the displacement m of the land portion surface side portion 5a _{1 in} the tire circumferential direction. Even in 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. Therefore, the fall of the small land portion is effectively prevented as in the first embodiment. Can be 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.

At this time, the displacement n in the tire circumferential direction of the land bottom side portion 5a ₂ is preferably larger than the displacement m in the tire circumferential direction of the land surface side portion 5a ₁ (m <n). This is because the degree of meshing between the small land portions 2a, that is, the support effect between the land portions can be increased.

  In the first embodiment and the second embodiment, as shown in FIGS. 3 and 5, in the sipe 5, the sipe depth at both ends of the sipe width direction is preferably shallower than the sipe depth at the center of the sipe width direction. . Thus, by providing shallow sipes at both ends in the width direction of the land portion 2, the land portion rigidity is secured, the land portion is prevented from falling down, and the dry performance and the wet performance when traveling on a normal road surface. Can be further improved. Moreover, since land surface side portions are provided at both ends in the width direction of the land portion, snow performance during running on a snowy road surface can be ensured at the same time.

The maximum depth H of the sipes is 60 to 90% of the circumferential groove depth, the depth _{H 1} of the land portion surface side portion 5a ₁ is 20 to 40% of the maximum depth H of the sipe It is preferable.
By arranging the land surface side portion 5a 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 region 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.2 (b), the small land parts subdivided by the sipe contact each other in the deep area | region of a land part. Therefore, by disposing the land portion bottom side portion 5a 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 surface side portion 5a ₁ in the above range, the functions of both the land surface side portion 5a ₁ and the land bottom side portion 5a ₂ can be exhibited most efficiently. Become.

Further, in sipes 5a, land portion surface side portion 5a _1, as shown in FIGS. 3 and 4, it is preferable to have one inflection point.
Thus, when the sipe 5a is greatly bent only once in the land surface vicinity region, the resistance to the road surface of the land surface side portion 5a 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 land portion surface side portion 5a ₁ of the sipe center plane 8, the tire circumferential direction displacement m the starting point bending point on the land portion surface S is the land portion surface side portion 5a ₁ it is preferably 0.2 to 0.4 times the depth distance _{H 1.}
The degree of bending of the land portion surface side portion 5a ₁ in the above range, penetration amount and digging amount into the snow of the small land portions 2a is increased. As a result, the snow performance can be further improved.

  In the pneumatic tire of the present invention, in addition to having the above-mentioned characteristic sipe, the sipe is further considered in consideration of the bending direction of the land surface side portion in the tire circumferential direction. It is characterized by being disposed on land.

Hereinafter, the sipe arrangement pattern in the tread portion having a plurality of land portions will be specifically described with reference to some pattern examples.
In the example of the pneumatic tire shown here, as shown in FIG. 1, block-like land portions are arranged in the tire circumferential direction to form a land portion row, and four rows of land portions are arranged in the tire width direction. Substrings are arranged (see FIG. 7). Further, this pneumatic tire is a tire whose rotational direction is the arrow direction shown in FIG. 7 when the tire rotates forward. Moreover, the sipe provided in each land part consists of the land part surface side part bent in the tire circumferential direction, and the land part bottom side part bent in the tire width direction, and shown in FIG. 3 and FIG. Is a sipe.

<First arrangement pattern>
In the first arrangement pattern, first, the bending direction toward the tire circumferential direction of each land portion surface side portion of the plurality of sipes is all the same direction in the same land portion row of the land portions arranged in the circumferential direction. Thus, it is important that the sipe 5 is disposed with respect to the land portion 2. That is, in the cross-sectional views (FIGS. 8A and 8B) when the land portion 2 in FIG. 7 is cut in the tire circumferential direction, the sipe center plane 8 is on the left side of the page in the vicinity of the land surface. It is important to bend only in one direction on the right side.

And in a 1st arrangement | positioning pattern, the land part which exists in the tread end TE side among the several land parts 2 arrange | positioned at the tread part 1 is made into shoulder side land part _RS , From this shoulder side land part _RS When the land portion on the tire equator line CL side is the center side land portion _RC , the bending direction toward the tire circumferential direction of the land portion surface side portion of the sipe of the shoulder side land portion _RS , and the center side land The bending direction toward the tire circumferential direction of the land portion surface side portion of the sipe of the portion _RC is a different direction.
The shoulder-side land portion _RS is at least the land portion on the tread end side, in the example shown in FIG. 7, all of the land portions constituting the same land portion row as the land portion 2A, and the same land portion as the land portion 2D All of the land that makes up the line. On the other hand, the center side land portion _RC is a land portion that is closer to the tire equator than the shoulder side land portion _RS, and in the example shown in FIG. 7, all the land portions that constitute the same land portion row as the land portion 2B. And all the land portions that constitute the same land portion row as the land portion 2C.

  Here, since the start acceleration is important for the snow performance, the rigidity of the land portion in the tread center region greatly affects. On the other hand, in dry performance and wet performance, since braking performance is important, the land portion rigidity in the tread shoulder region is greatly affected. Therefore, according to the sipe arrangement according to the first arrangement pattern, it is possible to improve the snow performance particularly in the center region, while improving the dry performance and the wet performance particularly in the shoulder region.

And in the center side land part _RC , as shown in FIG. 8 (a) in the cross-sectional view BB when the land part 2B is cut in the tire circumferential direction, particularly in the center side land part _RC . This is conspicuous when the sipe 5 is arranged so that the bending direction of the land surface side portion is opposite to the tire rotation direction, that is, the kicking side. On the other hand, in the shoulder side land portion _RS , as shown in FIG. 8 (b), the bending direction of the land portion surface side portion is as shown in FIG. 8 (b) when the land portion 2A is cut in the tire circumferential direction. This is remarkable when the sipe 5 is arranged so as to be on the tire rotation direction side, that is, on the stepping side.
According to this arrangement, in the center area that is effective for snow performance, when the tire is stepped forward during forward rotation, the sipe of the land surface side part opens and the edge digs up snow on the road surface, and the amount of penetration of the land into the snow Will increase. On the other hand, in the shoulder region effective for dry performance and wet performance, the bent convex portion on the land surface side is the stepping side, so that lifting deformation at the time of braking input is suppressed, and it is possible to secure a ground contact area. It is.

FIG. 7 shows an example in which only the land portion closest to the tread end is the shoulder-side land portion _RS and the center two rows of land portions are the center-side land portion _RC. When there are five rows, the land portion of the land portion row on the tread end side is the shoulder side land portion _RS and the land portion of the central three rows is the center side land portion _RC , Only the land part may be the center side land part _RC , and the other land part may be the shoulder side land part _RS .

  Moreover, although the case where the land part 2 is a block-shaped land part was shown in FIG. 7, the said 1st arrangement pattern is applicable also when the land part 2 is a rib-shaped land part. In this case, that is, the sipe 5 is such that the bending direction in the tire circumferential direction of each land portion surface side portion of the plurality of sipes is all the same in the same rib-shaped land portion continuous in the circumferential direction. However, it is important to be disposed with respect to the land portion 2.

<Second arrangement pattern>
In the second arrangement pattern, as in the first arrangement pattern, first, the bending direction toward the tire circumferential direction of each land portion surface side portion of the plurality of sipes is the same as the land portion arranged in the circumferential direction. It is important that the sipes 5 are arranged with respect to the land portion 2 so that they all have the same direction in the land portion row.

And in a 2nd arrangement | positioning pattern, the land part which exists in the tread end TE side among the some land parts 2 arrange | positioned at the tread part 1 is made into shoulder side land part _RS , From this shoulder side land part _RS When the land part on the tire equator line CL side is the center side land part _RC , the bending direction toward the tire circumferential direction of the land part surface side part of the sipe of the shoulder side land part _RS , and the center side land part The bending direction toward the tire circumferential direction of the land portion surface side portion of the _RC sipe is the same direction.
In other words, in the second arrangement pattern, the bending directions of the surface portions of the land portions of the sipe 5 in the tread portion 1 are all the same direction.

  According to this arrangement pattern, the bending direction of the land portion surface side portion of the sipe is the same in the entire region of the tread portion, so that the performance to be particularly improved among the snow performance, the dry performance, and the wet performance is improved. It is possible to ensure over the whole.

Accordingly, the bending direction of the land portion surface side portion of the center side land portion _RC is the tire rotation direction side (FIG. 9A), and the bending direction of the land portion surface side portion of the shoulder side land portion _RS is also the tire rotation direction. When the sipe is arranged so as to be on the side (FIG. 9B), the dry performance and wet performance can be particularly improved.
This is because, over the entire region of the tread portion, floating deformation at the time of braking input of the bent convex portion on the surface portion of the land portion is suppressed, and a ground contact area can be further secured.

On the contrary, the bending direction of the land surface side portion of the center side land portion _RC is opposite to the tire rotation direction (FIG. 10A), and the land surface surface portion of the shoulder side land portion _RS is When the sipe is arranged so that the bending direction is also opposite to the tire rotation direction (FIG. 10B), snow performance can be particularly improved.
When the land touches the road surface over the entire area of the tread, the sipe on the surface side of the land opens and the edge digs up snow on the road surface, and the amount of intrusion into the snow in the land increases. Because it becomes.

  In addition, although the case where the land part 2 was a block-shaped land part was shown in FIG. 7, the said 2nd arrangement | positioning pattern is applicable also when the land part 2 is a rib-shaped land part. In this case, the sipe 5 is in relation to the land portion 2 so that the bending direction toward the tire circumferential direction of each land portion surface side portion of the plurality of sipes is the same direction in all the rib-shaped land portions. It is important to be arranged.

<Third arrangement pattern>
In the following third arrangement pattern, first, the bending direction of each land portion surface side portion of a plurality of sipes is a region on one side in the tire circumferential direction and a tire circumferential direction on the other side in one block-like land portion. It is important that the sipe 5 is disposed with respect to the land portion 2 so as to be opposite to each other in the region.
11 and 12 show an arrow sectional view CC when the land portion 2A is cut in the tire circumferential direction, or an arrow sectional view BB when the land portion 2B is cut in the tire circumferential direction. Is. If it demonstrates concretely using FIG. 11, when the land part 2 is cut | disconnected by the width direction so that it may be equally divided by the tire circumferential direction, the sipe center plane 8 of the land part surface vicinity area of the tire circumferential direction one side is demonstrated. Is bent to the right side of the page, and the sipe center plane 8 on the other side in the tire circumferential direction is bent to the left side of the page. In other words, the bent convex portion on the land surface side portion is directed toward the center of the land portion 2. Or as shown in FIG. 12, the bending convex part of the land part surface side part has the structure which goes to the tire circumferential direction both ends side of the land part 2. As shown in FIG.

According to such an arrangement pattern, since the sipe 5 in which the bending direction of the land surface side portion is opposite to each other is provided in the same land portion, snow performance, wet performance, It becomes possible to ensure all performances equally.
And in particular, as shown in FIG. 12, the bent convex portion of the land surface side portion is directed to both ends in the tire circumferential direction of the land portion, so that the small block on the input / output side is smaller than the small block group on the input side. The contribution of the group to each performance increases. In this case, the edge on the input / output side easily penetrates into the snow on the snow road surface, and the floating deformation on the input / output side is suppressed on the dry / wet road surface. Snow performance, wet performance, and dry performance can be improved evenly.

And in the 3rd arrangement pattern, it is preferred that land part 2 which has the sipe shown in Drawing 11 or Drawing 12 in the whole tread part 1 is arranged.
This is because all the snow performance, dry performance, and wet performance can be ensured uniformly in the entire region of the tread portion 1 according to such a configuration.

  Next, inventive tires 1 to 5 according to the present invention and conventional tires according to the prior art were prototyped, and the snow performance, dry performance, and wet performance of each tire were evaluated.

  Specifically, the inventive tires 1 to 5 are 195 / 65R15 in size, applied rim 6J × 15, applied tread pattern shown in FIG. 7 with applied internal pressure 200 kPa, and the first embodiment shown in FIGS. 3 and 4. This is a radial tire for passenger cars having the sipe.

Invention Example Tire 1 is a pneumatic tire in which sipes are arranged on the entire tread portion in accordance with the first arrangement pattern. At this time, the sipe is arranged so that the bending direction of the land portion surface side portion of the center side land portion _RC is opposite to the tire rotation direction, that is, the kicking side (FIG. 8 ( a)). On the other hand, the sipe is disposed so that the bending direction of the land portion surface side portion of the shoulder side land portion _RS is the tire rotation direction side, that is, the stepping side (FIG. 8B).
Note that the depth H _{1 of} the land surface side portion 5a ₁ is 2.0 mm, the maximum sipe depth H is 7.0 mm, and the displacement m = 0.5 mm of the sipe center plane of the land surface side portion 5a ₁ . the displacement n = 0 mm sipe center plane of the land portion bottom portion 5a _2.

Invention example tire 2 is a pneumatic tire in which sipes are arranged on the entire tread portion in accordance with the second arrangement pattern. At this time, the bending direction of the land portion surface side portion of the center side land portion _RC and the bending direction of the land portion surface side portion of the shoulder side land portion _RS are both on the tire rotation direction side (FIG. 9). (A), (b)) Sipes are arranged. Other configurations are the same as those of the tire 1 of the invention.

The invention example tire 3 is a pneumatic tire in which sipes are arranged in the entire tread portion in accordance with the second arrangement pattern, similarly to the example tire 2. At this time, the bending direction of the land portion surface side portion of the center side land portion _RC and the bending direction of the land portion surface side portion of the shoulder side land portion _RS are both opposite to the tire rotation direction ( 10 (a) and 10 (b)) sipes are arranged. Other configurations are the same as those of the tire 1 of the invention.

  The invention example tire 4 is a pneumatic tire in which sipes are arranged on the entire tread portion in accordance with the third arrangement pattern. At this time, a plurality of sipes are arranged so that the bending direction of the land portion surface side portion of the sipe is directed toward the center of the land portion 2 with respect to one land portion (FIG. 11). Other configurations are the same as those of the tire 1 of the invention.

  Inventive tire 5 is a pneumatic tire in which sipes are arranged in the entire tread portion in accordance with the third arrangement pattern, similarly to the inventive tire 4. At this time, a plurality of sipes are arranged with respect to one land portion such that the bending direction of the land portion surface side portion of the sipe is directed toward both ends in the tire circumferential direction of the land portion 2 (FIG. 12). . Other configurations are the same as those of the tire 1 of the invention.

On the other hand, the conventional example tire is provided with a conventional two-dimensional sipe shown in FIG. 13 (a) that is zigzag on the land tread surface and extends linearly in the tire radial direction on the center side land portion _RC . The shoulder side land portion _RS has a zigzag shape on the land portion tread surface, and extends linearly in the region near the surface of the land portion in the tire radial direction, and is displaced in the tire width direction in a region deeper than that. This is a radial tire for passenger cars provided with a conventional three-dimensional sipe shown in FIG. 13 (b). Other configurations are the same as those of the tire of the invention example.

  These inventive example tires 1 to 5 and conventional example tires were respectively mounted on a vehicle and subjected to various evaluation tests. At this time, the inventive tires 1 to 3 were mounted on the vehicle so that the bending direction of the land surface side portion of each region in the tire circumferential direction is the above-described arrangement with respect to the tire rotation direction.

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 a vehicle was placed on a wet road surface and a braking distance was measured from when the initial speed was 80 km / h until full braking was applied until the vehicle became stationary. The dry performance was evaluated by performing a dry braking test in which the vehicle was placed on a dry road surface and the braking distance was measured until the vehicle became stationary when full braking was applied from the initial speed of 100 km / h.
The results are shown in Table 1. 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 1, it was found that all of the inventive tires 1 to 5 improved in snow performance, wet performance, and dry performance as compared with the conventional tires.
Especially, it turned out that the example tire 1 improves snow performance, wet performance, and dry performance markedly.
Moreover, it turned out that especially the invention example tire 2 can improve dry performance and wet performance notably. It was found that the inventive example tire 3 can significantly improve the snow performance.
Furthermore, it turned out that invention example tires 4 and 5 can improve all of snow performance, wet performance, and dry performance equally.

  According to the present invention, it is possible to provide a pneumatic tire in which all of snow performance, dry performance, and wet performance can be realized at a high level at the same time in a pneumatic tire provided with a sipe in a land portion.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Land part 2a Small land part 3 Circumferential groove | channel 4 Transverse groove 5 Sipe 5a ₁ Land part surface side part 5a ₂ Land part bottom side part 6 Corner part of the small land part 2a 7 Land part vicinity area of land part 2 Deeper region 8 Sipe center plane 9 Maximum sipe amplitude position P Intersection of center line L on sipe surface S and sipe 3 S Land surface L Center line of sipe amplitude f Maximum amplitude m Land surface side 3a ₁ tire circumferential direction displacement n tire circumferential direction displacement of land portion bottom side portion 3a ₂

Claims (7)

The tread portion includes a plurality of block-like land portions defined by rib-shaped land portions defined by circumferential grooves and / or lateral grooves intersecting the circumferential grooves and the circumferential grooves. In the pneumatic tire with multiple sipes in the part,
The sipe extends in the tire width direction with an amplitude in the tire circumferential direction, and bends in the tire circumferential direction with the land surface as a bending start position in the depth direction from the land surface to the inside in the tire radial direction. a land portion surface portion, and a land portion bottom portion that is bent toward the tire circumferential direction with a different displacement from the displacement of the land portion surface portion,
The displacement of the land portion bottom side portion in the tire circumferential direction is larger than the displacement of the land portion surface side portion in the tire circumferential direction,
The bending direction toward the tire circumferential direction of each land portion surface side portion of the plurality of sipes is in the same land portion continuous in the circumferential direction and in the row of the same land portion arranged in the circumferential direction. A pneumatic tire characterized by being all in the same direction. Bending direction of the land portion surface side portion of the sipe on the shoulder side land portion located on the tread end side, and bending of the land portion surface side portion of the sipe portion of the center side land portion located on the tire equator side from the shoulder side land portion The pneumatic tire according to claim 1, wherein the directions are different directions. Bending direction of the land portion surface side portion of the sipe on the shoulder side land portion located on the tread end side, and bending of the land portion surface side portion of the sipe portion of the center side land portion located on the tire equator side from the shoulder side land portion The pneumatic tire according to claim 1, wherein the directions are the same direction. 2. The pneumatic tire according to claim 1, wherein the sipe has a sipe depth at both ends of the sipe width direction that is shallower than a sipe depth at the center of the sipe width direction. In a pneumatic tire having a plurality of block-shaped land portions defined by a circumferential groove and a transverse groove intersecting the circumferential groove in the tread portion, and having a plurality of sipes on the land portion,
The sipe extends in the tire width direction with an amplitude in the tire circumferential direction, and bends in the tire circumferential direction with the land surface as a bending start position in the depth direction from the land surface to the inside in the tire radial direction. a land portion surface portion, and a land portion bottom portion that is bent toward the tire circumferential direction with a different displacement from the displacement of the land portion surface portion,
The displacement of the land portion bottom side portion in the tire circumferential direction is larger than the displacement of the land portion surface side portion in the tire circumferential direction,
The bending direction toward the tire circumferential direction of each land portion surface side portion of the plurality of sipes is opposite to each other in the tire circumferential direction one side region and the tire circumferential direction other side region in the same land portion. A pneumatic tire characterized by being.   The pneumatic tire according to claim 5, wherein a land portion provided with the sipe is disposed on the entire tread portion. The pneumatic tire according to claim 5, wherein the sipe 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.

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