JP2003159911A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of preventing increase of biased wear and deterioration of pattern noise and improving drainage. <P>SOLUTION: Since a hollow part 22 is formed in a central side land part 16, drainage can be secured. Since the hollow part 22 emerges on the surface of the tire after a wear middle period of the central side land part 16, drainage can be more effectively secured. In addition, rigidity of an outside land part in the radial direction of the tire of the hollow part is lowered by providing the hollow part 22, and since contact of the chamfered part of the land part and a road surface can be avoided, biased wear can be effectively prevented by chamfering and inclining an edge 18 with low rigidity. Furthermore, since the hollow part 22 is provided in only the neighborhood of the bottom part of a central slit 14, increase of an air volume in the slit 14 can be suppressed as much as possible, and deterioration of pattern noise can be prevented as much as possible. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire capable of preventing uneven wear and deterioration of pattern noise and improving drainage.

[0002]

2. Description of the Related Art Generally, a conventional pneumatic tire has a circumferential groove (main groove) extending in the tire circumferential direction and an inclined groove (lug groove) extending in the tire axial direction with an inclination with respect to the tire circumferential direction. , Are provided.

Here, in order to improve the wet high-prevention property, the groove width is widened or the like to form a groove area (negative).
There are possible ways to increase.

However, if the groove width is widened, the drainage property is generally improved. However, if the groove width is simply widened, the rigidity of the block is lowered and uneven wear is increased, or pattern noise is generated due to an increase in the air volume in the groove. There is a problem that gets worse.

Further, it is general that the circumferential groove secures drainage in the tire circumferential direction and the inclined groove secures drainage in the tire axial direction. However, by providing the inclined groove, continuous smoothness is achieved. There is a problem that grounding is impaired and it becomes a source of pattern noise.

On the other hand, in a block row in which cut grooves such as sipes are not formed, not only the wet drainage performance is deteriorated, but also grip on a road having a low friction coefficient (low μ road),
There is a problem that the riding comfort deteriorates due to too high block rigidity.

Further, noise reduction can be achieved by stopping the inclined groove without opening it in the circumferential groove, but this causes a problem that wet drainage performance is deteriorated.

Further, by raising the bottom of at least a part of the inclined groove, the block rigidity can be increased and uneven wear can be suppressed, and the air volume in the groove can be reduced to reduce noise. There is a problem that sex deteriorates. In particular, there is a problem that the wet drainage property of the block after abrasion is significantly deteriorated.

[0009]

In view of the above facts, the present invention provides a pneumatic tire capable of preventing an increase in uneven wear and deterioration of pattern noise and improving drainage. It is an issue.

[0010]

According to the invention of claim 1, a plurality of circumferential grooves extending in the tire circumferential direction and a plurality of land portions defined by the circumferential grooves and continuous in the tire circumferential direction are treaded. In the pneumatic tire having, in the tread, a slit extending in the tire width direction, a chamfer formed at one of the stepping side or the kicking side sandwiching the slit, and near the bottom of the slit. It is characterized in that at least one land portion is provided which has a hollow portion formed toward at least the inside of the land on the edge forming side of the slit.

Next, the function and effect of the pneumatic tire according to claim 1 will be described.

In the pneumatic tire of the present invention, since the hollow portion is formed in the land slit, drainage can be ensured. In particular, after the middle stage of wear of the land portion, the hollow portion appears on the tire surface, so that the drainage property can be more effectively ensured.

On the other hand, by providing the hollow portion in the slit of the land portion, the rigidity of the land portion outside the hollow portion in the tire radial direction is reduced. Due to this decrease in rigidity, there is concern that uneven wear may increase (progress).

Therefore, by chamfering and inclining the land portion having low rigidity, it is possible to avoid contact between the chamfered portion of the land portion and the road surface, so that uneven wear can be effectively prevented.

Since the chamfered portion does not come into contact with the ground, a gap is formed between the road surface and the land surface, so that the drainage property at the initial stage of wear can be further improved.

Further, since the hollow portion is provided in the vicinity of the bottom portion of the slit, it is possible to suppress the increase of the air volume in the slit due to the provision of the hollow portion as much as possible and prevent the deterioration of pattern noise as much as possible. In addition, noise can be reduced by making the land portion continuous in the tire circumferential direction.

As described above, according to the pneumatic tire of the present invention, it is possible to prevent the increase of uneven wear and the deterioration of pattern noise, and to improve the drainage property.

The invention according to a second aspect is the pneumatic tire according to the first aspect, wherein the slit having the chamfer and the hollow portion is formed in the land portion partitioned by a pair of circumferential grooves. It is characterized by

Next, the function and effect of the pneumatic tire of claim 2 will be described.

Near the center of the ground contact area, that is, the tread area on the tire equatorial plane side of the outermost land portion in the tire width direction is
The ground contact area is far from the ground contact edge in the vicinity of both ends in the tire width direction, that is, the tread area near the shoulder portion, and is a region in which drainage is severe.

In the pneumatic tire of the present invention, the tread area on the tire equatorial plane side of the outermost land portion in the tire width direction,
That is, since a slit having a chamfer and a hollow portion is provided in the land portion defined by the pair of circumferential grooves, it is preferable in order to ensure the drainage property more effectively.

According to a third aspect of the present invention, in the pneumatic tire according to the first or second aspect, the outermost land portion in the tire width direction is chamfered to form a hollow portion. The feature is that there is no slit.

Next, the function and effect of the pneumatic tire of claim 3 will be described.

Of the tread, the vicinity of the shoulder portion is a severe portion against wear, and if the hollow portion is provided and the rigidity of the land portion is reduced, uneven wear (heel and toe wear) may occur. Therefore, when uneven wear may occur in the land portion on the outermost side in the tire width direction, only a chamfer is formed in the slit of the land portion without forming a hollow portion, and the rigidity of the land portion is appropriately reduced. Preferably.

The invention according to claim 4 is the pneumatic tire according to any one of claims 1 to 3.
The slit is formed to be inclined with respect to the tire axial direction, and in a plan view of the land portion, an edge near an acute angle end of the land portion is chamfered and inclined.

Next, the function and effect of the pneumatic tire of claim 4 will be described.

In the pneumatic tire of the present invention, the slits are formed so as to be inclined with respect to the tire axial direction, so that the corners of the land portions are acute in plan view. If the corner portion becomes an acute angle, the rigidity of that portion is reduced, and uneven wear may increase.

Therefore, in plan view of the land portion, by chamfering the edge near the acute angle end of the land portion, it is possible to avoid the ground contact between the low rigidity portion of the land portion and the road surface, thus increasing uneven wear. Can be prevented.

According to a fifth aspect of the present invention, in the pneumatic tire according to any one of the first to fourth aspects,
On one side of the slit in the tire axial direction, one of the edges on the stepping side or the kicking side of the land portion sandwiching the slit is chamfered and inclined, and the other side in the tire axial direction of the slit. Then, the edge of the land portion on the opposite side across the slit is chamfered and inclined with respect to the land portion chamfered on one side of the slit in the tire axial direction.

Next, the function and effect of the pneumatic tire according to claim 5 will be described.

On one side of the slit in the tire axial direction, one of the edges of the land portion sandwiching the slit on the stepping side or the kicking side is chamfered and inclined, and on the other side of the slit in the axial direction of the tire. , The edge of the land portion on the opposite side of the slit is chamfered and inclined with respect to the land portion chamfered on one side in the tire axial direction of the slit, so that each land portion divided by the slit is chamfered. Will have both sharp edges and non-chamfered edges.

Therefore, the ground pressure is different between the chamfered edge portion and the non-chamfered edge portion in one land portion, and the so-called impact component (a pattern block edge which is a source of pattern noise (excitation source) is Since the batting input of, and the same applies to the following) are dispersed, it is possible to reduce noise.

Further, since the chamfered portion (edge) does not contact the road surface, a drainage effect can be obtained.

The invention according to claim 6 is the pneumatic tire according to any one of claims 1 to 4, wherein:
The slit is formed in a bent shape having a curved portion in the middle, and with the curved portion of the slit as a boundary, on one side in the tire axial direction, the stepping side edge of the land portion sandwiching the slit is chamfered and inclined. On the other side in the tire axial direction, the edge on the kicking side of the land portion sandwiching the slit is chamfered and inclined.

Next, the function and effect of the pneumatic tire according to claim 6 will be described.

With the curved portion of the slit as a boundary, the edge on the stepping side of the land portion sandwiching the slit is chamfered and inclined on one side in the tire axial direction, and the land sandwiching the slit is formed on the other side in the tire axial direction. Since the edge on the kicking side of the portion is chamfered and inclined, one slit in each land portion has both a chamfered edge portion and an edge portion without chamfering.

Therefore, the ground pressure is different between the chamfered edge portion and the non-chamfered edge portion in one land portion, and so-called impact components are dispersed, so that noise reduction can be achieved.

Further, since the chamfered edge portion does not contact the road surface, a drainage effect can be obtained, and
By forming the slit in a bent shape, the rigidity of each land portion can be improved and uneven wear can be prevented as much as possible.

The invention according to claim 7 is the pneumatic tire according to any one of claims 1 to 4, wherein:
The slit is formed across a plurality of land portions adjacent to each other in the tire axial direction with the circumferential groove interposed therebetween, and the land with the slit sandwiched on one side in the tire axial direction with the circumferential groove as a boundary. The edge on the stepping side of the part is chamfered and inclined, and on the other side in the tire axial direction, the edge on the kicking side of the land portion that sandwiches the slit is chamfered and inclined, It is characterized by that.

Next, the function and effect of the pneumatic tire according to claim 7 will be described.

With the circumferential groove as a boundary, on the one side in the tire axial direction, the edge on the stepping side of the land portion sandwiching the slit is chamfered and inclined, and on the other side in the tire axial direction, the land portion sandwiching the slit is formed. By chamfering and inclining the edge on the kick-out side, noise reduction can be achieved for the same reason as in claims 3 and 4.

At the same time, since the chamfered edge portion does not contact the road surface, a drainage effect can be obtained.

The invention according to claim 8 is the pneumatic tire according to any one of claims 1 to 7, wherein:
The slit width of the slit is formed so as to widen toward the circumferential groove or the end portion in the tire axial direction.

Next, the function and effect of the pneumatic tire according to claim 8 will be described.

Since the slit width of the slit is formed so as to widen toward the circumferential groove or the tire axial end portion, the water component easily flows into the circumferential groove or the tire axial end portion. Therefore, the drainage effect can be further improved.

The slit width of the slit means the width (shortest width) measured substantially perpendicular to the axial direction of the slit.

The invention according to claim 9 is the pneumatic tire according to any one of claims 1 to 8.
The wall surface of the slit is characterized in that it has flat portions that come into contact with each other when the slit faces the road surface immediately below a load.

Next, the function and effect of the pneumatic tire according to claim 9 will be described.

When the slit is directly under the load facing the road surface,
The flat surfaces of the wall surfaces of the slits contact each other. By this contact, the rigidity of the land portion partitioned by the slit in the tire circumferential direction is improved. Therefore, uneven wear can be effectively prevented.

Further, the braking performance can be improved by bringing the flat surfaces of the wall surfaces of the slits into contact with each other.

Further, since the flat portions of the wall surfaces of the slits are in contact with each other, land contact in the tire circumferential direction divided by the slits is continuous, so that so-called impact component can be reduced and pattern noise can be reduced. it can.

Since the hollow portion is formed, the drainage performance does not deteriorate even if the flat portions of the wall surfaces of the slits contact each other.

A tenth aspect of the present invention is the pneumatic tire according to any one of the first to ninth aspects, wherein the chamfered width of the edge is 2 times or more and 7 times the slit width of the slit. It is characterized by the following.

Next, the function and effect of the pneumatic tire according to claim 10 will be described.

If the chamfered width of the edge is less than twice the slit width of the slit, the drainage property is not effectively improved and it is inappropriate.

On the other hand, if the chamfered width of the edge is greater than 7 times the slit width of the slit, pattern noise is likely to occur, which is inappropriate.

The chamfered width of the edge means the width (shortest width) measured substantially perpendicular to the axial direction of the slit.

The slit width of the slit means the width (shortest width) measured substantially perpendicular to the axial direction of the slit.

An eleventh aspect of the present invention is the pneumatic tire according to any one of the first to tenth aspects, wherein the chamfering depth of the edge in the slit depth direction is equal to that of the circumferential groove. It is characterized in that it is 10% or more and 30% or less of the groove depth.

Next, the function and effect of the pneumatic tire according to claim 11 will be described.

If the chamfered depth of the edge in the slit depth direction is less than 10% of the groove depth of the circumferential groove, the drainage property is not effectively improved, which is inappropriate.

On the other hand, if the chamfer depth of the edge in the slit depth direction is larger than 30% of the groove depth of the circumferential groove, pattern noise is likely to occur, which is inappropriate.

A twelfth aspect of the invention is the pneumatic tire according to any one of the first to eleventh aspects, wherein the chamfer is 10 ° to 4 ° with respect to the tread of the land portion.
It is characterized in that it is inclined within a range of 5 °.

Next, the function and effect of the pneumatic tire according to claim 12 will be described.

When the chamfering angle is less than 10 °, the drainage property is not improved effectively and is inappropriate.

On the other hand, when the chamfering angle exceeds 45 °,
Pattern noise is likely to occur, which is inappropriate.

According to a thirteenth aspect of the present invention, in the pneumatic tire according to any one of the first to twelfth aspects, the hollow portion is the groove bottom from the groove bottom with reference to the groove bottom. It is characterized in that it is provided in a region of 30% or more and 70% or less of the groove depth of the slit.

Next, the function and effect of the pneumatic tire according to claim 13 will be described.

If the region in which the hollow portion is provided is less than 30% of the groove depth of the slit from the groove bottom with respect to the groove bottom of the slit, drainage is not effectively improved, which is inappropriate. .

On the other hand, the region in which the hollow portion is provided has a groove depth of 7 from the groove bottom with respect to the groove bottom of the slit.
If it is greater than 0%, pattern noise is likely to occur, and the land surface is largely moved to cause uneven wear, which is inappropriate.

A fourteenth aspect of the present invention is the pneumatic tire according to any one of the first to thirteenth aspects, wherein the expanded width of the hollow portion is at least twice the slit width of the slit. It is 5 times or less and less than or equal to the sum of the chamfer width of the edge and the slit width of the slit.

Next, the function and effect of the pneumatic tire according to claim 14 will be described.

If the expanded width of the hollow portion is less than twice the slit width of the slit, a sufficient drainage effect cannot be obtained, which is inappropriate.

On the other hand, if the expanded width of the hollow portion is larger than 5 times the slit width of the slit, the volume of the hollow portion becomes too large. For this reason, when the slit is directly under the load facing the road surface, the surface of the land portion largely moves and uneven wear easily occurs, which is inappropriate.

Further, when the expanded diameter of the hollow portion becomes wider than the sum of the chamfer width of the edge and the slit width of the slit, the edge of the land portion is chamfered so as not to come into contact with the road surface. Is not appropriate and is inappropriate.

The diameter expansion width of the hollow portion means the maximum diameter of the hollow portion measured substantially perpendicular to the axial direction of the slit.

Further, the meaning of the chamfer width of the edge and the slit width of the slit are the same as described in the operation of claim 8.

According to a fifteenth aspect of the present invention, in the pneumatic tire according to any one of the first to fourteenth aspects, in the slit having the hollow portion, the hollow portion forms an edge of the slit. It is characterized in that it is formed only inside the land portion on the side, and is not formed toward the inside of the land portion in the direction opposite to the edge forming side.

Next, the operation of the pneumatic tire according to claim 15 will be described.

As described in the operation of the first aspect, by providing the hollow portion in the slit of the land portion, the rigidity of the land portion outside the hollow portion in the tire radial direction is lowered. When providing a hollow portion in the slit, if the hollow portion is formed both on the inside of the land portion on the chamfer forming side and on the inside of the land portion in the opposite direction to the chamfer forming side,
There is a concern that uneven wear may occur in the land portion on the side opposite to the chamfer forming side.

The uneven wear generated in the land portion on the side opposite to the chamfer forming side is small, and it should be good if there is no problem in actual use. However, if there is a problem in actual use, the hollow portion should have a slit edge. It is preferable to form only on the inside of the land portion on the formation side and not on the inside of the land portion in the direction opposite to the edge formation side to suppress the cause of uneven wear as much as possible.

[0082]

BEST MODE FOR CARRYING OUT THE INVENTION A pneumatic tire according to a first embodiment of the present invention will be described below with reference to the accompanying drawings. (First Embodiment) As shown in FIGS. 1 and 2, a pneumatic tire 10 of this embodiment has a center block 12 formed in the vicinity of the tire equator line CL.

A bent central slit 14 (slit) having a bent portion is formed in the center block 12, and the center block 12 causes the center block 12 to have a plurality of land portions 16 (hereinafter, It is appropriately divided into the central side land portion 16.).

The bent portion of the central slit 14 is formed substantially at the center of the central slit 14 in the tire axial direction. Further, the axial direction of the central slit 14 is formed so as to be inclined with respect to the tire axial direction.

Here, with reference to the curved portion of the central slit 14, the central side land portion 16 is located on the right side in the tire axial direction (see FIG. 1).
In the middle arrow R direction), the edge 1 on the stepping side (the arrow X direction in FIG. 1) of the center side land portion 16 sandwiching the center slit 14
8 is chamfered and inclined.

As shown in FIG. 2, the central slit 14
The slit width A is preferably set to 0.7 mm or more and 1.2 mm or less.

The chamfer width B of the edge 18 is set to be not less than 2 times and not more than 5 times the slit width A of the central slit 14, and particularly preferably not less than 2 mm and not more than 5 mm.

The chamfering depth C of the edge 18 in the central slit depth direction is set to 10% or more and 30% or less of the groove depth of the first circumferential groove 20 described later, and particularly 1 m.
It is preferably m or more and 2 mm or less.

Further, the chamfering angle θ (with respect to the tread surface) of the edge 18 is preferably within the range of 10 ° to 45 °.

Further, in the vicinity of the groove bottom of the central slit 14, more specifically, in the region of 30% or more and 70% or less of the groove depth Z of the central slit 14 from the groove bottom as a reference, an edge is formed. A hollow portion 22 having an enlarged diameter is formed on the same side as the chamfered side of 18.

The expanded diameter D of the hollow portion 22 is determined by the central slit 1
The slit width A of 4 is set to 2 times or more and 5 times or less, and the chamfer width B of the edge 18 and the central slit 14 are set.
It is set to be equal to or less than the sum of the slit widths A.

As described above, one of the opposing groove walls of the central slit 14 is constituted by the vertical surface 24 formed linearly in the tire radial direction, while the other is chamfered and inclined. The inclined surface 26, the vertical surface 28 that is linearly formed in the tire radial direction, and the curved surface 30 that is curved to form the hollow portion 22.

It is to be noted that the vertical surface 24 of one groove wall and the vertical surface 28 of the other groove wall are configured to come into contact with each other when the central slit 14 is directly under a load facing the road surface.

On the other hand, as shown in FIG. 1, the central slit 1
On the left side in the tire axial direction of the central side land portion 16 (direction of arrow L in FIG. 1) with reference to the curved portion of 4, the kicking side of the central side land portion 16 with the central slit 14 interposed (direction of arrow Y in FIG. 1). Edge 32 is chamfered and inclined.

Further, in the vicinity of the groove bottom of the central slit 14, more specifically, in the region of 30% or more and 70% or less of the groove depth Z of the central slit 14 from the groove bottom as a reference, the edge is formed. A hollow portion (not shown) having an enlarged diameter is formed on the same side as the chamfered side of 32.

The chamfer width of the edge 32 and the edge 3
The dimension of chamfering depth 2 in the slit depth direction is the same as the dimension of the edge 18 located on the right side in the tire axial direction of the central side land portion 16 with reference to the curved portion of the central slit 14.

The chamfering angle θ (with respect to the tread surface) of the edge 32 is preferably in the range of 10 ° to 45 °.

Further, the expanded diameter width of the hollow portion also depends on the central slit 1.
It is the same as the size of the hollow portion 22 located on the right side in the tire axial direction of the central side land portion 16 with reference to the curved portion of 4.

As described above, in the plan view of the tread, the edges 18 and 32 near the acute-angled end of each central side land portion 16 are chamfered and inclined.

Next, on the outer side (both sides) in the tire axial direction of the central side land portion 16, the first circumferential groove 2 extending in the tire circumferential direction is provided.
Two 0s are formed.

On the right (outer) side in the tire axial direction of the first circumferential groove 20 located on the right side in the tire axial direction, a plurality of intermediate land portions 34 are formed along the tire circumferential direction. Intermediate slits 36 that are inclined with respect to the tire axial direction are formed between the intermediate land portions 34 that are adjacent to each other in the tire circumferential direction.

A second circumferential groove 38 extending in the tire circumferential direction is formed on the right side in the tire axial direction of the intermediate land portion 34.

On the right side of the second circumferential groove 38 in the tire axial direction, a plurality of end side land portions 40 are arranged along the tire circumferential direction.
Are formed.

An end slit 42 (slit) extending in the tire axial direction is formed between the end side land portions 40 adjacent to each other in the tire circumferential direction.

The slit width of the end slit 42 is 0.7 mm or more and 1.2 mm or more, like the central slit 14.
It is preferably set to be equal to or less than mm.

Here, each end side land portion 40 is divided in the tire axial direction by the third circumferential groove 44.

That is, each end-side land portion 40 has a first end-side land portion 46 located on the inner side in the tire axial direction and a second end-side land portion 48 located on the outer side in the tire axial direction. It is composed of.

The edge 50 on the kicking side of the first end side land portion 46 is chamfered and inclined.

Also, as shown in FIG. 2, the end slit 4
2 near the groove bottom, specifically, 30% of the groove depth Z from the groove bottom to the end slit 42 with reference to the groove bottom of the end slit 42.
In the region of 70% or less, a hollow portion 52 having a diameter increased on the same side as the chamfered side of the edge 50 is formed.

The dimensions of the chamfer width B of the edge 50 and the chamfer depth C of the edge 50 in the slit depth direction are the same as the dimensions of the chamfered edges 18 and 32 of each central land portion 16.

The chamfering angle θ (with respect to the tread surface) of the edge 50 is preferably in the range of 10 ° to 45 °.

The expanded width D of the hollow portion 52 is also the same as the dimension of the hollow portion 22 formed in the central land portion 16.

Further, the edge 54 on the kicking side of the second end side land portion 48 is chamfered and inclined.

Further, as shown in FIG. 2, the end slit 4
30% or more and 70% or more of the groove depth Z of the end slit 42 with reference to the groove bottom of the end slit 42.
In the following region, a hollow portion 56 having a diameter increased on the same side as the chamfered side of the edge 54 is formed.

The dimensions of the chamfer width B of the edge 54 and the chamfer depth C of the edge 54 in the slit depth direction are the same as the dimensions of the chamfered edges 18, 32 of each central side land portion 16.

The chamfering angle θ (with respect to the tread surface) of the edge 54 is preferably within the range of 10 ° to 45 °.

The expanded diameter D of the hollow portion 56 is also the same as the size of the hollow portion 22 formed in the central land portion 16.

Similarly, the vertical surface 24 of one groove wall and the vertical surface 28 of the other groove wall are configured to come into contact with each other when the end slit 42 is directly under a load facing the road surface. .

In addition, sipes 58 are formed on each of the second end side land portions 48 so as to have a T-shape in a tread plan view.

On the other hand, a plurality of intermediate land portions 34 are formed along the tire circumferential direction on the tire axial left (outer) side of the first circumferential groove 20 located on the tire axial left side. Intermediate slits 36 that are inclined with respect to the tire axial direction are formed between the intermediate land portions 34 that are adjacent to each other in the tire circumferential direction.

A second circumferential groove 38 extending in the tire circumferential direction is formed on the left side in the tire axial direction of the intermediate land portion 34.

An end side land portion 40 is formed on the left side in the tire axial direction of the second circumferential groove 38.

An end slit 42 (slit) extending in the tire axial direction is formed between the end side land portions 40 adjacent to each other in the tire circumferential direction.

The slit width of the end slit 42 is 0.7 mm or more and 1.2 mm or more, like the central slit 14.
It is preferably set to be equal to or less than mm.

Here, each end side land portion 40 is divided in the tire axial direction by the third circumferential groove 44.

That is, each end-side land portion 40 has a first end-side land portion 46 located inside the tire axial direction, a second end-side land portion 48 located outside the tire axial direction, and It is composed of.

The edge 60 on the stepping side of the first end side land portion 46 is chamfered and inclined.

Further, in the vicinity of the groove bottom of the end slit 42, specifically, in the region of 30% or more and 70% or less of the groove depth Z of the end slit 42 with reference to the groove bottom of the end slit 42, the edge 60 is provided. A hollow portion (not shown) having an enlarged diameter is formed on the same side as the chamfered side.

The chamfer width of the edge 60 and the edge 6
The dimension of the chamfer depth of 0 in the slit depth direction is the same as the dimension of the chamfered edges 18 and 32 of each central side land portion 16.

The chamfering angle θ of the edge 60 (with respect to the tread surface) is preferably within the range of 10 ° to 45 °.

Further, the diameter expansion width of the hollow part is
The dimensions are the same as the dimensions of the hollow portion 22 formed in.

Further, the edge 62 on the stepping side of the second end side land portion 48 is chamfered and inclined.

Further, in the vicinity of the groove bottom of the end slit 42, specifically, in the region of 30% or more and 70% or less of the groove depth Z of the end slit 42 with reference to the groove bottom of the end slit 42, the edge 62 is formed. A hollow portion is formed on the same side as the chamfered side.

The chamfer width of the edge 62 and the edge 6
The dimension of the chamfering depth in the slit depth direction of 2 is the same as the dimension of the chamfered edges 18 and 32 of each central side land portion 16.

The chamfering angle θ (with respect to the tread surface) of the edge 62 is preferably within the range of 10 ° to 45 °.

Further, the diameter expansion width of the hollow portion also depends on the central side land portion 16
The dimensions are the same as the dimensions of the hollow portion 22 formed in.

Similarly, when the end slit 42 directly under the load facing the road surface, the vertical surface (not shown) of one groove wall and the vertical surface (not shown) of the other groove wall are opposite to each other. Configured to contact.

Further, sipes 58 are formed on each of the second end side land portions 48 so as to have a T-shape in a tread plan view.

Next, the operation and effect of the pneumatic tire 10 will be described.

According to the pneumatic tire 10 of the present invention, in the vicinity of the groove bottoms of the central slit 14 and the end slits 42,
Since the hollow portions 22, 52, and 56 are formed, drainage can be ensured.

In particular, each central side land portion 16 and each end side land portion 4
Since the hollow portions 22, 52, 56 appear on the surface of the tire 10 after the middle wear period of 0, drainage can be more effectively ensured.

On the other hand, by providing the hollow portions 22, 52, 56, the rigidity of the land portions 16, 46, 48 on the tire radial outside of the hollow portions 22, 52, 56 decreases. Due to this decrease in rigidity, there is concern that uneven wear may increase (progress).

However, the edges 18 and 3 of the land portion having low rigidity
Since 2, 50, 54, 60, 62 are chamfered and inclined, contact between the chamfered portion of each land portion 16, 46, 48 and the road surface can be avoided, and uneven wear can be effectively prevented. .

Since the chamfered portion does not come into contact with the ground, a gap is created between the road surface and the land surface, so that the drainage performance can be further improved.

Further, since the hollow portions 22, 52, 56 are provided near the bottom of the central slit 14 and the end slit 42, the central slit 14 and the end slits due to the provision of the hollow portions 22, 52, 56. The increase of the air volume in 42 can be suppressed as much as possible, and the deterioration of pattern noise can be prevented as much as possible.

As described above, the pneumatic tire 10 of the present invention
According to this, it is possible to prevent uneven wear and deterioration of pattern noise and improve drainage.

In particular, in the pneumatic tire 10 of this embodiment, since the central slit 14 is formed to be inclined with respect to the tire axial direction, each central side land portion 16 divided in the tire circumferential direction is It has a corner that is an acute angle in a plan view.

By the way, if the corner portion becomes an acute angle, the volume of the land portion at that portion becomes small, so that the rigidity of the land portion may decrease and uneven wear may increase.

Therefore, in plan view of the central land portion 16, the edges 18, 32 near the acute-angled end of the central land portion 16 are arranged.
By chamfering, it is possible to avoid the ground contact between the low rigidity portion of the central side land portion 16 and the road surface, so that it is possible to effectively prevent an increase in uneven wear.

Further, with the curved portion of the central slit 14 as a boundary, on the right side in the tire axial direction, the edge 18 on the stepping side of the central side land portion 16 sandwiching the slit is chamfered and inclined, and on the left side in the axial direction of the tire. Since the edge 32 on the kicking side of the center side land portion 16 that sandwiches the slit 14 is chamfered and inclined, in one center slit 14 of each center side land portion 16, the chamfered edge portion and the chamfer are formed. Will have both edges that are not present.

For this reason, the ground pressure is different between the chamfered edge portion and the non-chamfered edge portion in one central land portion 16, and so-called impact components are dispersed, so that noise reduction can be achieved.

Further, since the chamfered edge portion does not contact the road surface, a drainage effect can be obtained and
By forming the central slit 14 in a bent shape, the rigidity of each central land portion 16 can be improved and uneven wear can be prevented as much as possible.

Here, each edge 18, 32, 50, 5
The edges 18, 32, 50, 54, 60, 62 are set to have the chamfering width B of 4, 60, 62 not less than 2 times and not more than 5 times the slit width A of the central slit 14 and the end slit 42.
The chamfer width B of the central slit 14 and the end slit 42
If it is less than twice the slit width A, the drainage property is not effectively improved and becomes inappropriate.

On the other hand, each edge 18, 32, 50, 54,
If the chamfer width B of 60, 62 is made larger than 5 times each slit width A of the central slit 14 and the end slit 42,
This is because pattern noise is likely to occur and is inappropriate.

Further, each edge 18, 32, 50, 54,
The chamfering depth C in the slit depth direction of 60, 62 is set to be 10% or more and 30% or less of the groove depth of each circumferential groove 20, 44 because each edge 18, 32, 50, 54, 60, 62. The chamfer depth C in the slit depth direction of each of the circumferential grooves 20, 4 is
This is because if it is less than 10% of the groove depth of 4, the drainage is not effectively improved and it becomes inappropriate.

On the other hand, each edge 18, 32, 50, 54,
This is because if the chamfering depth C of the slit depth direction of 60, 62 is larger than 30% of the groove depth of each circumferential groove 20, 44, pattern noise is likely to occur and it becomes unsuitable.

Further, each edge 18, 32, 50, 54,
The chamfering angle θ of 60, 62 (with respect to the tread) is 10 ° ~
The range of 45 ° is that the chamfering angle θ is less than 10 °, the drainage is not effectively improved, and the chamfering angle θ is 45 °.
This is because if it exceeds the range, pattern noise is likely to occur.

Further, each hollow portion 22, 52, 56 has a groove depth Z of 30 of the central slit 14 and the end slit 42 with reference to the groove bottoms of the central slit 14 and the end slit 42.
% To 70% of the area is 30%
If it is less than, the drainage will not be effectively improved,
Because it will be inappropriate. On the other hand, if it is larger than 70%, pattern noise is likely to occur and the surface of the land portion is largely moved to cause uneven wear, which is unsuitable.

Further, the expanded width D of each hollow portion 22, 52, 56 is not less than 2 times and not more than 5 times the slit width A of the central slit 14 and the end slit 42, and each edge 1
The reason why the sum of the chamfer width B of 8, 32, 50, 54, 60 and 62 and the slit width A of the central slit 14 or the end slit 42 is less than or equal to is the expanded diameter width D of the hollow portions 22, 52 and 56.
Is less than twice the slit width A of the central slit 14 and the end slit 42, a sufficient drainage effect cannot be obtained, which is inappropriate.

On the other hand, if it becomes larger than 5 times, the hollow portion 2
The volumes of 2, 52, and 56 become too large, and the surface of the central side land portion 16 and the end side land portion 40 moves largely when the central slit 14 and the end slit 42 face the road surface immediately below the load, and the uneven wear occurs. Is likely to occur and becomes inappropriate.

The expanded width D of each hollow portion 22, 52, 56 is the sum of the chamfer width B of the edges 18, 32, 50, 54, 60, 62 and the slit width A of the central slit 14 or the end slit 42. This is because if it becomes wider, the effect of suppressing uneven wear of the central side land portion 16 and the end side land portion 40 cannot be obtained, which is unsuitable.

Further, the wall surfaces of the central slit 14 and the end slit 42 are the same as those of the central slit 14 and the end slit 4.
Since 2 has the vertical surfaces 24 and 28 that are in contact with each other immediately below the load facing the road surface, the flat surfaces of the wall surfaces of the central slit 14 and the end slit 42 are in contact with each other immediately below the load.

By this contact, the rigidity of each of the center side land portion 16 and the end side land portion 40 divided in the tire circumferential direction by the center slit 14 and the end slit 42 is improved. Therefore, uneven wear can be effectively prevented. Also,
The braking performance can be improved.

Further, when the flat surfaces of the wall surfaces of the central slit 14 and the end slit 42 contact each other, the ground contact of the central side land portion 16 and the end side land portion 40 adjacent to each other in the tire circumferential direction to the road surface continues. The so-called impact component can be reduced and the pattern noise can be reduced.

The slit width A of the central slit 14 and the end slit 42 is 0.7 mm or more and 1.2 mm.
The reason for setting below is that if it is less than 0.7 mm, the central side land portion 16 and the end side land portion 40 become hard and the riding comfort is deteriorated, so that it is not suitable. This is because the impact component is insufficiently reduced and thus becomes inappropriate. (Second Embodiment) Next, a pneumatic tire according to a second embodiment of the present invention will be described.

[0166] The pneumatic tire 10 of the first embodiment.
The same configurations as those of the above are denoted by the same reference numerals, and the description thereof will be appropriately omitted.

As shown in FIG. 3, the pneumatic tire 70 according to this embodiment is the pneumatic tire 10 of the first embodiment.
Compared with, the chamfering method of the edges 72, 74 of the end side land portion 40 is different.

That is, with the third circumferential groove 44 located on the right side in the tire axial direction as a boundary, the edge 72 on the stepping side is chamfered and inclined at the first end side land portion 46 on the inner side in the tire axial direction. There is.

In addition, in the vicinity of the groove bottom of the end slit 42, specifically, in the region of 30% or more and 70% or less of the groove depth of the end slit 42 with reference to the groove bottom of the end slit 42, the edge 72 is formed. A hollow portion (not shown) having an enlarged diameter is formed on the same side as the chamfered side.

Also, with the third circumferential groove 44 located on the right side in the tire axial direction as a boundary, at the second end side land portion 48 on the outer side in the tire axial direction, the edge 74 on the kicking side is chamfered and inclined. ing.

Similarly, a hollow portion (not shown) whose diameter is enlarged is formed on the same side as the chamfered side of the edge 74.

On the other hand, with the third circumferential groove 44 located on the left side in the tire axial direction as a boundary, in the first end side land portion 46 on the inner side in the tire axial direction, the edge 76 on the kicking side is chamfered and inclined. ing.

Similarly, a hollow portion (not shown) whose diameter is enlarged is formed on the same side as the chamfered side of the edge 76.

Further, with the third circumferential groove 44 located on the right side in the tire axial direction as a boundary, the edge 78 on the stepping side is chamfered and inclined at the second end side land portion 48 on the outer side in the tire axial direction. There is.

Further, similarly, a hollow portion (not shown) having an enlarged diameter is formed on the same side as the chamfered side of the edge 78.

According to the pneumatic tire 70 of this embodiment, the edges 72, 74, 76, 78 of the land portions 40 on the respective end portions are provided.
Since the chamfering is performed as described above, the impact component can be dispersed and the noise can be reduced.

In particular, in the pneumatic tire 70 of this embodiment, pattern noise can be greatly reduced as compared with the pneumatic tire 10 of the first embodiment.

At the same time, the chamfered edge portion does not come into contact with the road surface, so that the drainage effect can be obtained. (Third Embodiment) Next, a pneumatic tire according to a third embodiment of the present invention will be described.

[0179] The pneumatic tire 10 of the first embodiment.
The same configurations as those of the above are denoted by the same reference numerals, and the description thereof will be appropriately omitted.

As shown in FIG. 4, in the pneumatic tire 80 according to this embodiment, the edges 86 and 88 of the intermediate land portion 84 divided in the tire circumferential direction by the intermediate slit 82 are also chamfered.

The intermediate land portion 84 corresponds to a land portion formed by combining the intermediate land portion 34 and the first end side land portion 46 (see FIG. 1) of the pneumatic tire 10 of the first embodiment. Therefore, in the pneumatic tire 80 of the present embodiment, the circumferential groove corresponding to the second circumferential groove 38 (see FIG. 1) is not formed.

The intermediate slit 82 is provided on the central side land portion 16
Similar to the central slit 14 formed in the above, the central slit 14 is formed in a bent shape having a bent portion in the approximate center.

Here, on the right side in the tire axial direction (see arrow R in FIG. 4).
Direction) in each of the intermediate land portions 84 located on the right side in the tire axial direction of the intermediate land portion 84 with reference to the curved portion of the intermediate slit 82, the intermediate land portion 84 sandwiching the intermediate slit 82.
The edge 86 on the kicking side (direction of arrow Y in FIG. 4) is chamfered and inclined.

The slit width of the intermediate slit 82 is preferably set to 0.7 mm or more and 1.2 mm or less.

The chamfer width of the edge 86 and the edge 8
The chamfering depth of the intermediate slit 6 in the depth direction of 6 is the edges 18, 32, 50, 5 of the pneumatic tire 10 of the first embodiment.
It is set similarly to 4, 60, and 62.

Further, in the vicinity of the groove bottom of the intermediate slit 82, specifically, in the region of 30% or more and 70% or less of the groove depth of the intermediate slit 82 with reference to the groove bottom of the intermediate slit 82, the chamfered side of the edge 86 is formed. A hollow portion (not shown) whose diameter is expanded is formed on the same side.

It should be noted that the dimension setting of the expanded diameter width of the hollow portion is also the first
Hollow portions 22, 52, 5 of the pneumatic tire 10 of the embodiment
It is similar to 6.

Similarly, the vertical surface of one groove wall and the vertical surface of the other groove wall are configured to come into contact with each other when the intermediate slit 82 is directly under a load facing the road surface.

Further, with reference to the curved portion of the intermediate slit 82, the left side of the intermediate land portion 84 in the tire axial direction (arrow L in FIG. 4).
(Direction), the edge 88 of the intermediate land portion 84 sandwiching the intermediate slit 82 on the stepping side (direction of arrow X in FIG. 4) is chamfered and inclined.

Further, in the vicinity of the groove bottom of the intermediate slit 82, specifically, in the region of 30% or more and 70% or less of the groove depth of the intermediate slit 82 with reference to the groove bottom of the intermediate slit 82, the chamfered side of the edge 88 is formed. A hollow portion (not shown) whose diameter is expanded is formed on the same side.

On the other hand, in each of the intermediate land portions 84 located on the left side in the tire axial direction, on the right side in the tire axial direction of the intermediate land portion 84 with reference to the bending portion of the intermediate slip 82, the intermediate land portion 84 sandwiching the intermediate slit 82 is formed. Edge 90 on the kicking side
Is chamfered and inclined.

Further, in the vicinity of the groove bottom of the intermediate slit 82, specifically, in the region of 30% or more and 70% or less of the groove depth of the intermediate slit 82 with reference to the groove bottom of the intermediate slit 82, the chamfered side of the edge 90 is formed. A hollow portion (not shown) whose diameter is expanded is formed on the same side.

Further, on the left side of the intermediate land portion 84 in the tire axial direction with reference to the curved portion of the intermediate slit 82, the edge 92 on the stepping side (the arrow X direction in FIG. 4) of the intermediate land portion 84 sandwiching the intermediate slit 82 is Beveled and inclined.

Further, in the vicinity of the groove bottom of the intermediate slit 82, specifically, in the region of 30% or more and 70% or less of the groove depth of the intermediate slit 82 with reference to the groove bottom of the intermediate slit 82, the chamfered side of the edge 92 is formed. A hollow portion (not shown) whose diameter is expanded is formed on the same side.

As described above, in the pneumatic tire 80 of this embodiment, the edges 86, 88, 90, 92 of the stepping side or the kicking side of the intermediate land portion 84 are also chamfered.

Further, a second circumferential groove 45 is formed on the outer side of the intermediate land portion 84 in the tire axial direction.

An end side land portion 94 is formed on the outer side in the tire axial direction of the second circumferential groove 45.

That is, the end-side land portion 94 is divided in the tire circumferential direction by the end slits 96, and each end-side land portion 94 has two inner circumferential slits 98 and outer portions having different slit widths. The circumferential slits 100 are formed at intervals.

The inner circumferential slit 98 has a narrow slit width, and the outer circumferential slit 100 has a wide slit width.

Further, at each end side land portion 94, sipes 102 connecting the inner circumferential slit 98 and the outer circumferential slit 100 are formed.

Here, at the end side land portion 94 located on the right side in the tire axial direction, the edge 104 on the kicking side of the end side land portion 94 is chamfered and inclined.

Further, in the vicinity of the groove bottom of the end slit 96, specifically, in the region of 30% or more and 70% or less of the groove depth of the end slit 96 with reference to the groove bottom of the end slit 96, the edge 104 is formed. A hollow portion (not shown) having an enlarged diameter is formed on the same side as the chamfered side.

The chamfering width of the edge 104 is formed so as to increase toward the inner side in the tire axial direction. Therefore, the slit width of the end slit 104 becomes wider toward the outer end in the tire axial direction.

On the other hand, in the end side land portion 94 located on the left side in the tire axial direction, the edge 1 on the stepping side of the end side land portion 94 is used.
06 is chamfered and inclined.

Further, in the vicinity of the groove bottom of the end slit 96, specifically, in the region of 30% or more and 70% or less of the groove depth of the end slit 96 with reference to the groove bottom of the end slit 96, the edge 106 is formed. A hollow portion (not shown) having an enlarged diameter is formed on the same side as the chamfered side.

The chamfering width of the edge 106 is formed so as to become wider toward the inner side in the tire axial direction. Therefore, the slit width of the end slit 96 becomes wider toward the outer end in the tire axial direction.

Also in the pneumatic tire 80 of this embodiment, the pneumatic tires 1 of the first and second embodiments are also provided.
Similar to 0 and 70, it is possible to prevent increase of uneven wear and deterioration of pattern noise, and improve drainage.

In particular, in the pneumatic tire 80 of this embodiment, the pattern noise can be further reduced as compared with the pneumatic tires 10 and 70 of the first and second embodiments. (Fourth Embodiment) Next, a pneumatic tire according to a fourth embodiment of the present invention will be described.

The pneumatic tire 80 of the third embodiment
The same configurations as those of the above are denoted by the same reference numerals, and the description thereof will be appropriately omitted.

As shown in FIG. 5, in the pneumatic tire 110 of this embodiment, a center block 112 is formed near the tire equator line CL.

The center block 112 includes the pneumatic tires 10, 70 of the first to third embodiments.
Unlike 80, the central slit 14 (see FIG. 1) is not formed, and the edges are not chamfered.

On the outside of the center block 112 in the axial direction of the tire, first circumferential grooves 20 extending in the tire circumferential direction are formed.

On the outer side of the first circumferential groove 20 in the tire axial direction, a rib-shaped intermediate land portion 114 continuous in the tire circumferential direction is formed.

The intermediate land portion 114 is formed with a sipe 116 which is inclined with respect to the tire axial direction. In addition,
A plurality of the sipes 116 are formed at predetermined intervals in the tire circumferential direction.

Here, on the right side in the tire axial direction (arrow R in FIG. 5)
A circumferential slit 118 extending in the tire circumferential direction is formed in the intermediate land portion 114 located in the (direction).

Further, the inclined slit 120 extends from the end of the circumferential slit 118 to the second circumferential groove 45 described later.
(Slit) is connected. This inclined slit 12
0 is inclined with respect to the tire axial direction.

The circumferential slit 118 and the inclined slit 120 are formed in each region of the intermediate land portion 114 divided by the sipes 116.

Further, the circumferential slit 118 and the inclined slit 120 are formed so as to be convex on the stepping side of the intermediate land portion 114.

The edge of the intermediate land portion 114 facing the inclined slit 120 and facing in the tire circumferential direction,
Edge 1 on the stepping side with reference to the inclined slit 120
22 is chamfered and inclined.

The chamfering width of the edge 122 is formed so as to become narrower toward the second circumferential groove 45. Therefore, the slit width of the inclined slit 120 becomes wider toward the second circumferential groove 45.

Further, in the vicinity of the groove bottom of the inclined slit 120, specifically, in the region of 30% or more and 70% or less of the groove depth of the inclined slit 120 with reference to the groove bottom of the inclined slit 120, the chamfered side of the edge 122 is formed. A hollow portion (not shown) whose diameter is expanded is formed on the same side.

On the other hand, in the intermediate land portion 114 located on the left side in the tire axial direction (the direction of the arrow L in FIG. 5), the circumferential slit 1 is formed.
18 and the inclined slit 120 are formed, the inclined slit 120 is symmetrical with respect to the line extending in the tire axial direction as compared with the inclined slit 120 formed in the intermediate land portion 114 on the right side in the tire axial direction. Has been formed.

That is, the circumferential slits 118 and the inclined slits 120 are formed so as to be convex on the trailing side of the intermediate land portion 114.

Further, the edge of the intermediate land portion 114 facing the inclined slit 120 and facing in the tire circumferential direction,
Edge 1 on the kicking side with reference to the inclined slit 120
24 is chamfered and inclined.

The chamfering width of the edge 124 is formed so as to become narrower toward the second circumferential groove 45. Therefore, the slit width of the inclined slit 120 becomes wider toward the second circumferential groove 45.

Further, in the vicinity of the groove bottom of the inclined slit 120, specifically, in the region of 30% or more and 70% or less of the groove depth of the inclined slit 120 with reference to the groove bottom of the inclined slit 120, the chamfered side of the edge 124 is formed. A hollow portion (not shown) whose diameter is expanded is formed on the same side.

As described above, in the pneumatic tire 110 of this embodiment, the edges 122 and 12 of each intermediate land portion 114 are formed.
4 is chamfered.

A second circumferential groove 45 extending in the tire circumferential direction is formed on the outer side in the tire axial direction of each intermediate land portion 114.

On the right side in the tire axial direction of the second circumferential groove 45, an end side land portion 126 continuous in the tire circumferential direction is formed.

The end side land portion 126 is formed with an end portion slit 128 which is open toward the tire axial direction end portion side.

Further, on the end side land portion 126, an inner circumferential slit 130 and an outer circumferential slit 132 having different slit widths are formed at intervals, and are respectively connected to the end slits 128. ing.

Further, sipes 134 connecting the inner circumferential slits 130 and the outer circumferential slits 132 are formed in each end side land portion 126.

Each end side land portion 126 is formed with a sipe 136 which connects the end portion of the inner circumferential slit 130 and the second circumferential groove 45.

Here, at the end side land portion 126 located on the right side in the tire axial direction, the stepping side edge 138 of the end side land portion 126 sandwiching the end slit 128 is chamfered and inclined.

Further, in the vicinity of the groove bottom of the end slit 128, specifically, in the region of 30% or more and 70% or less of the groove depth of the end slit 128 with reference to the groove bottom of the end slit 128, the edge 138 is formed. A hollow portion (not shown) having an enlarged diameter is formed on the same side as the chamfered side.

The chamfer width of the edge 138 is formed so as to become wider toward the inner side in the tire axial direction. Therefore, the slit width of the end slit 126 becomes wider toward the outer end in the tire axial direction.

On the other hand, an end side land portion 126 which is continuous in the tire circumferential direction is formed on the left side in the tire axial direction of the second circumferential groove 45. The end side land portion 126 is formed with an end slit 128 that is open to the end side in the tire axial direction.

On the end side land portion 126, inner circumferential slits 130 and outer circumferential slits 132 having different slit widths are formed at intervals in the tire axial direction, and the end slits 128 are respectively formed. Connected.

Further, at each end side land portion 126, a sipe 134 connecting the inner circumferential slit 130 and the outer circumferential slit 132 is formed.

The end side land portion 126 is formed with a sipe 136 which connects the end portion of the inner circumferential slit 130 and the second circumferential groove 45.

The pattern of the end side land portion 126 located on the left side in the tire axial direction and the pattern of the end side land portion 126 located on the right side in the tire axial direction are symmetrical with respect to a line extending in the tire axial direction. Is formed in.

Here, in the end side land portion 126 located on the left side in the tire axial direction, the edge 140 on the kicking side of the end side land portion 126 sandwiching the end portion slit 128 is chamfered and inclined.

Further, in the vicinity of the groove bottom of the end slit 128, specifically, in the region of 30% or more and 70% or less of the groove depth of the end slit 128 with reference to the groove bottom of the end slit 128, the edge 140 is formed. A hollow portion (not shown) having an enlarged diameter is formed on the same side as the chamfered side.

The chamfering width of the edge 140 is formed so as to increase toward the inner side in the tire axial direction. Therefore, the slit width of the end slit 128 becomes wider toward the outer end in the tire axial direction.

According to the pneumatic tire 110 of the present embodiment, the pneumatic tires 1 of the first and second embodiments are provided.
Similar to 0 and 70, it is possible to prevent increase of uneven wear and deterioration of pattern noise, and improve drainage.

In particular, the pneumatic tire 110 of this embodiment.
According to this, since the slit width of the inclined slit 120 is formed so as to widen toward the second circumferential groove 45, the water component easily flows into the second circumferential groove 45. Therefore, the drainage effect can be further improved. Further, similarly, since the slit width of the end slit 128 is formed so as to widen toward the tire axial direction end side, the water component is easily discharged to the tire axial direction end side. Therefore, the drainage effect can be further improved. (Fifth Embodiment) Next, a pneumatic tire according to a fifth embodiment of the present invention will be described.

The pneumatic tire of this embodiment is a modification of the pneumatic tire 10 of the first embodiment. The first
The same components as those of the pneumatic tire 10 of the embodiment are designated by the same reference numerals, and the description thereof will be appropriately omitted.

The pneumatic tire 142 of this embodiment has the same tread pattern (see FIG. 1) as the pneumatic tire 10 of the first embodiment, but as shown in FIG.
The end slit 4 formed in the second end side land portion 48
In No. 2, the hollow portion 56 is not formed.

In the center side land portion 16 and the first end side land portion 46, as shown in FIGS. 11 (A) and 11 (B),
It has the same sectional shape as the pneumatic tire 10 of the first embodiment.

When the hollow portion 56 is provided in the vicinity of the shoulder portion where wear is more severe than in the tread center portion, the rigidity of the land portion of the second end side land portion 48 becomes too low and uneven wear (heel and toe) occurs. Wear).

Therefore, if there is a risk of uneven wear of the second end side land portion 48, it is preferable not to form the hollow portion 56 in the end slit 42 as in the present embodiment.

In the above embodiment, the hollow portion is formed only inside the land portion on the chamfer forming side. However, if uneven wear is small and there is no problem, the inside of the land portion on the opposite side to the chamfer forming side is formed. It may be formed by anyone.

For example, as shown in FIG. 12, in the end slit 42, the hollow portion 56 is formed on the chamfer forming side (the inclined surface 26).
When formed on the land portion on the formation side) and on the land portion on the opposite side to the chamfer formation side, the diameter expansion width D of the hollow portion 56 is
It is preferable to set it to 3 times or less of the slit width A of 2.

The diameter expansion width D of the hollow portion 52 is equal to the end slit 4
When it exceeds 3 times the slit width A of 2, the rigidity of the land portion on the side where the inclined surface 26 is not formed is lowered, and there is a concern that uneven wear may occur near the edge where the inclined surface 26 is not formed.

The same applies to the expanded diameter width D of the hollow portion 22 and the expanded diameter width D of the hollow portion 52. (Test Example) Next, using the pneumatic tire of each of the above-described embodiments and a conventional pneumatic tire, tests were performed on wet high-pre performance (straight line), wet brake performance, dry steering stability test, and pattern noise.

Here, the respective dimensions of the pneumatic tire (invention pattern A) according to the first embodiment used in this test were set as follows.

The respective dimensions are as shown in Table 1 below and FIG. 6 (numerical values in the figures are in mm).

6A is a sectional view taken along the line AA of FIG. 1, FIG. 6B is a sectional view taken along the line BB of FIG. 1, and FIG. 6C is a sectional view taken along the line CC of FIG. Is.

[0259]

[Table 1] Further, the respective dimensions of the pneumatic tire (invention pattern B) according to the second embodiment used in this test were set as follows.

The respective dimensions are as shown in Table 2 below and FIG. 7 (numerical values in the figures are in mm).

7A is a sectional view taken along line AA of FIG. 3, FIG. 7B is a sectional view taken along line BB of FIG. 3, and FIG. 7C is a sectional view taken along line CC of FIG. Is.

[0262]

[Table 2] Further, the respective dimensions of the pneumatic tire (invention pattern C) according to the third embodiment used in this test were set as follows.

The respective dimensions are as shown in Table 3 below and FIG. 8 (numerical values in the figures are in mm).

8A is a sectional view taken along the line AA of FIG. 4, FIG. 8B is a sectional view taken along the line BB of FIG. 4, and FIG. 8C is a sectional view taken along the line CC of FIG. Is.

[0265]

[Table 3] Further, the respective dimensions of the pneumatic tire (invention pattern D) according to the fourth embodiment used in this test were set as follows.

The respective dimensions are as shown in Table 4 below and FIG. 9 (numerical values in the figures are in mm).

FIG. 9A is a sectional view taken along the line AA of FIG. 5, and FIG. 9B is a sectional view taken along the line BB of FIG.

[0268]

[Table 4] Next, the conventional pneumatic tire used in this test will be described.

As shown in FIG. 10, a conventional pneumatic tire 200 has a central side land portion 202 extending in the tire circumferential direction. The central side land portion 202 is formed with a central slit 204 which is inclined with respect to the tire axial direction.

A first circumferential groove 206 extending in the tire circumferential direction is formed outside the center side land portion 202 in the tire axial direction. An intermediate land portion 208 is formed on the outer side of the first circumferential groove 206 in the tire axial direction. Midland part 20
8 is an intermediate slit 2 inclined with respect to the tire axial direction.
10 are formed.

A second circumferential groove 212 extending in the tire circumferential direction is formed on the outer side of the intermediate land portion 208 in the tire axial direction.

An end side land portion 214 is formed on the outer side of the second circumferential groove 212 in the tire axial direction.

The end side land part 214 is formed with an end part slit 216 extending in the tire axial direction, and the end part side land part 214 is divided by the end part slit 216 in the tire circumferential direction.

Further, each end side land portion 214 is formed with an inner circumferential slit 218 extending in the tire circumferential direction, and the inner circumferential slit 218 causes each end side land portion 214 to move in the tire axial direction. It is divided.

Therefore, the end-side land portion 214 includes the first end-side land portion 220 located inside the tire axial direction, the second end-side land portion 222 located outside the tire axial direction, It is composed of.

The second end side land portion 222 is formed with an outer circumferential slit 224 which is open to the end slit 216 and extends in the tire circumferential direction.

Further, each end side land portion 214 is formed with sipes 226 which connect the inner circumferential slit 218 and the outer circumferential slit 224.

In this way, the conventional pneumatic tire 200
In, the land portions are not chamfered and hollow portions are not formed.

The respective dimensions of the conventional pneumatic tire (conventional pattern) were set as follows.

The respective dimensions are as shown in Table 5 below.

[0281]

[Table 5] The pneumatic tire of each of the above-described embodiments used in this test has a tire size of PSR205 / 65R15 and a tread width of 160 mm.

The inner pressure of each tire is 2.0 kg / cm.
The test was conducted with two persons, a test driver and a measurement operator.

Here, the wet high pre-performance (straight line) is a feeling evaluation of the high pre-production limit speed when passing through a wet road having a water depth of 5 mm.

[0284] The wet braking performance means that the water depth is 2
It means the braking distance when full braking is performed on a straight road surface of mm from a running state of 80 km / h.

The dry steering stability test is an evaluation of the feeling of a test driver when sports driving on a dry circuit course in various driving modes.

Further, the pattern noise is a feeling evaluation of the in-vehicle sound when coasting from 100 km / h on a straight smooth road.

The results of this test are shown in Table 6 below.

The numerical values in Table 6 are index evaluations,
The larger the value, the better.

[0289]

[Table 6] As shown in Table 6 above, each of the tires of the invention patterns A to D, which is the pneumatic tire of the present invention, has a wet high pre-performance (straight line) as compared with the tire of the conventional pattern which is a conventional pneumatic tire. Wet brake performance,
It was found to be good in all dry steering stability tests and pattern noise.

From the above, in the pneumatic tire of the present invention, increase in uneven wear and deterioration of pattern noise are prevented,
It can be said that drainage can be improved.

[0291]

According to the pneumatic tire of the present invention, it is possible to prevent an increase in uneven wear and aggravation of pattern noise, and to improve drainage.

[Brief description of drawings]

FIG. 1 is a plan view showing a tread pattern of a pneumatic tire according to a first embodiment of the present invention.

2A is a sectional view taken along line AA of FIG. 1, FIG. 2B is a sectional view taken along line BB of FIG. 1, and FIG. 2C is a sectional view taken along line CC of FIG.

FIG. 3 is a plan view showing a tread pattern of a pneumatic tire according to a second embodiment of the present invention.

FIG. 4 is a plan view showing a tread pattern of a pneumatic tire according to a third embodiment of the present invention.

FIG. 5 is a plan view showing a tread pattern of a pneumatic tire according to a fourth embodiment of the present invention.

6A is a sectional view taken along line AA of FIG. 1, FIG. 6B is a sectional view taken along line BB of FIG. 1, and FIG. 6C is a sectional view taken along line CC of FIG.

7A is a sectional view taken along line AA of FIG. 3, FIG. 7B is a sectional view taken along line BB of FIG. 3, and FIG. 7C is a sectional view taken along line CC of FIG.

8A is a sectional view taken along line AA of FIG. 4, FIG. 8B is a sectional view taken along line BB of FIG. 4, and FIG. 8C is a sectional view taken along line CC of FIG.

9A is a sectional view taken along line AA of FIG. 5, and FIG. 9B is a sectional view taken along line BB of FIG.

FIG. 10 is a plan view showing a tread pattern of a conventional pneumatic tire.

11A is a cross-sectional view of a central land portion of the fifth embodiment, FIG. 11B is a cross-sectional view of a first end portion land portion of the fifth embodiment, and FIG. It is sectional drawing of the 2nd edge part side land part of 5th Embodiment.

FIG. 12 is a cross-sectional view of a second end side land portion of another embodiment.

[Explanation of symbols]

10 pneumatic tires 14 Central slit (slit) 16 Central side land area (land area) 18 Edge 20 First circumferential groove (circumferential groove) 22 Hollow part 24 Vertical surface (flat surface) 28 Vertical surface (flat surface) 32 edges 38 Second circumferential groove (circumferential groove) 40 Edge side land area (land area) 42 End slit (slit) 44 Third circumferential groove (circumferential groove) 45 Second circumferential groove (circumferential groove) 50 edges 52 hollow 54 Edge 56 hollow 60 edge 62 edge

Claims (15)

[Claims] 1. A pneumatic tire having on a tread a plurality of circumferential grooves extending in the tire circumferential direction and a plurality of land portions defined by the circumferential grooves and continuous in the tire circumferential direction, wherein the tread has: A slit extending in the tire width direction, a chamfer formed on either the stepping side or the kicking side sandwiching the slit, and a land portion inward on the edge forming side of the slit provided near the bottom of the slit. A pneumatic tire having at least one land portion having a hollow portion formed toward the front side. 2. The pneumatic tire according to claim 1, wherein the slit having the chamfer and the hollow portion is formed in the land portion defined by a pair of circumferential grooves. 3. The tire according to claim 1, wherein the outermost land portion in the tire width direction is provided with a chamfer and a slit having no hollow portion. Pneumatic tire. 4. The slit is formed to be inclined with respect to the tire axial direction, and in plan view of the land portion, an edge near an acute angle end of the land portion is chamfered and inclined. The pneumatic tire according to any one of claims 1 to 3. 5. On one side of the slit in the tire axial direction, one of the edge on the stepping side or the side on the kicking side of the land portion sandwiching the slit is chamfered and inclined, and the tire of the slit is formed. On the other side in the axial direction, the edge of the land portion on the opposite side across the slit is chamfered and inclined with respect to the land portion chamfered on one side of the tire axial direction of the slit, that The pneumatic tire according to any one of claims 1 to 4, which is characterized. 6. The slit is formed in a bent shape having a curved portion in the middle thereof, and with the curved portion of the slit as a boundary, on one side in the tire axial direction, an edge on the stepping side of the land portion sandwiching the slit. Is chamfered and inclined, and on the other side in the tire axial direction, the edge on the kicking side of the land portion sandwiching the slit is chamfered and inclined,
The pneumatic tire according to any one of claims 1 to 4, which is characterized by the above. 7. The slit is formed across a plurality of land portions adjacent to each other in the tire axial direction with the circumferential groove sandwiched therebetween, and the slit is provided on one side in the tire axial direction with the circumferential groove as a boundary. The edge on the stepping side of the land portion sandwiching the is chamfered and inclined, and on the other side in the tire axial direction, the edge on the kicking side of the land portion sandwiching the slit is chamfered and inclined. The pneumatic tire according to any one of claims 1 to 4, characterized in that. 8. The slit width of the slit is formed so as to widen toward the circumferential groove or the end portion in the tire axial direction, according to any one of claims 1 to 7. The pneumatic tire according to item. 9. The wall surface of the slit has flat surface portions which come into contact with each other when the slit faces the road surface immediately below a load, and the wall surface of the slit has a flat surface portion. Pneumatic tires. 10. The pneumatic tire according to claim 1, wherein the chamfered width of the edge is 2 times or more and 7 times or less the slit width of the slit. . 11. The chamfering depth of the edge in the slit depth direction is 10% or more and 30% or less of the groove depth of the circumferential groove, according to any one of claims 1 to 10. The pneumatic tire according to item 1. 12. The chamfer according to claim 1, wherein the chamfer is inclined within a range of 10 ° to 45 ° with respect to a tread surface of the land portion. Pneumatic tire. 13. The hollow portion is provided in a region from the groove bottom to 30% or more and 70% or less of the groove depth of the slit with reference to the groove bottom of the slit. The pneumatic tire according to any one of claims 1 to 12. 14. The expanded width of the hollow portion is not less than 2 times and not more than 5 times the slit width of the slit, and is not more than the sum of the chamfer width of the edge and the slit width of the slit. The pneumatic tire according to any one of claims 1 to 13, which is characterized. 15. In the slit having the hollow portion, the hollow portion is formed only inside the land portion on the edge forming side of the slit, and is formed toward the inside of the land portion opposite to the edge forming side. The pneumatic tire according to any one of claims 1 to 14, wherein the pneumatic tire does not exist.