JPH05338418A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To lower rib rigidity and to effectively prevent rib wear from being produced by providing an inclined siping inclined in the depth direction against a flat surface passing a tire rotation axis and the direction from a siping bottom toward the opening end of a tire surface of which matches the positive rotational direction of the tire. CONSTITUTION:On the circumference of a shoulder rib 5 sandwiched by a tire shoulder end part 2 and a longitudinal groove 3, a plural number of inclined sipings 10 crossing between the adjacent longitudinal grooves 3, 3 and between the longitudinal groove 3 and the shoulder end part 2 and dividing ribs 4, 5 into a narrow block 11 and a wide block 12 are formed with an interval. These inclined sipings 10 are constituted to be inclined in the depth direction against a flat surface P passing a tire rotation axis and so that the direction from a siping bottom 10a to a tire surface opening end 10b of the sipings matches a positive rotational direction R of a tire. Additionally, the narrow block 11 is made to be a protruded block protruding from the wide block 12 constituting the tire surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to an improvement in uneven wear prevention which occurs in a peripheral edge portion of a rib sandwiched by vertical grooves in a pneumatic tire having a rib pattern.

[0002]

2. Description of the Related Art In the case of a pneumatic tire having a rib pattern, stepwise abnormal wear may occur at the peripheral end portions on both sides of the rib sandwiched by vertical grooves during running. This is usually called riverware, but conventionally, various technical measures have been taken and proposed to prevent this riverware.

As the most commonly used means, there is a technique in which a large number of sipes, one end of which is open to a longitudinal groove, are formed at the end of the rib at minute intervals in the tire width direction. Further, there is disclosed a technique of forming a continuous or intermittent sipe substantially parallel to the vertical groove at a position slightly apart from the rib end along the rib end. Further, a technique of reducing the zigzag of the vertical groove to form a substantially linear shape is also an effective means.

[0004]

However, when a large number of sipes, one end of which is open to a vertical groove, are formed at the rib end portion at minute intervals in the tire width direction, the rib end portion has a large circumferential rigidity. It is effective in that it can increase the followability to the circumferential force that weakens the sipe and causes uneven wear, but if a large number of sipes are formed at the rib end at minute intervals, this sipe can cause May cause cracks and chipping.

Further, in the prior art in which a sipe is formed along the rib end at a position slightly apart from the rib end, the movement of the rib end in the tire width direction is controlled, whereby slippage in the circumferential direction is suppressed and deviation is caused. I'm trying to prevent wear,
In such a means, the narrow region sandwiched by the sipe and the vertical groove does not contribute to the wear durability and reduces the wear durability of the tire, and this configuration has a drawback that a tear is likely to occur at the rib end.

On the other hand, the conventional technique in which the vertical groove has a linear shape has less problems as compared with the above technique, but is not always sufficient in terms of preventing uneven wear.

An object of the present invention is to provide a pneumatic tire which can effectively prevent river wear which occurs at both circumferential end portions of ribs sandwiched by vertical grooves during running.

[0008]

Means for Solving the Problems In the meantime, uneven wear of the rib pattern is caused by river wear, cupping in which the river wear locally progresses in the width direction of the rib, and further, one rib as a whole wears more than other ribs. There are also rib punches that can quickly make one step, but in any case, the wiping action of the tire and the movement in the tire width direction based on the shearing force of the tire surface generated by the vertical load reduce the frictional force in the circumferential direction. Slip in the tire circumferential direction becomes large at the end portion of the rib having a large degree, which causes wear. Therefore, in order to prevent this, it is effective to weaken the rigidity in the circumferential direction of the ribs so that even if the frictional force becomes weak, the weakened frictional force can be sufficiently followed.

In this respect, it is preferable to form a large number of sipes, one end of which is open to the vertical groove, at the rib end portion at minute intervals, but as described above, there is a problem that such means cause cracks and chipping during traveling. .. Therefore, in this invention, in order to achieve the same function and effect as forming a large number of sipes at minute intervals at the rib peripheral end portion while reducing the number of sipes formed as much as possible, the rotation direction of the tire is Select a tire with specified directionality and incline the sipe at the rib end that opens into the vertical groove in the depth direction with respect to the plane including the tire rotation axis, and incline from the sipe bottom to the sipe tire surface. It was constructed as an inclined sipe whose direction coincides with the tire normal rotation direction. As a result, when a vertical load is applied to the tire, the tire tends to move in the direction of rotation, so that the followability is improved and uneven wear prevention is greatly improved.

On the other hand, in order to weaken the rigidity in the circumferential direction of the rib, it can be achieved by cutting the rib from one vertical groove to the other vertical groove by sipes and blocking the rib, and the effect is more remarkable. become. That is, in the circumferential direction of the tire tread portion, ribs in the inner region sandwiched on both sides by a plurality of continuous vertical grooves, and a shoulder in which one end is a tire shoulder end portion and the other end is sandwiched in the vertical groove. In a pneumatic tire having a rib, on the circumference of the rib in at least the inner region, cross between adjacent vertical grooves, and form a plurality of sipes that divide the rib to form a block, and The sipe is an inclined sipe that is inclined in the depth direction with respect to a plane passing through the tire rotation axis, and the direction from the sipe bottom toward the open end of the tire surface of the sipe matches the normal rotation direction of the tire.

However, if the ribs are made into blocks, a circumferential force that causes slippage is generated between the front end portion and the rear end portion in the circumferential direction separated by sipes, though not so much as the lateral groove, due to the relationship with the rotation direction of the tire. Since the combined force distribution of the circumferential shearing force based on the vertical load is different, unsightly uneven wear called so-called toe and heel in which the wear state is different due to the difference in the slip state is likely to occur. Although it can be prevented by setting the width of the sipe to zero, it is technically difficult to set the width to 0.3 mm or less in reality. If the tire is post-processed and knife-cut, the width can be made very close to zero, but there are problems in terms of cost and flexibility in design.

Therefore, according to the present invention, in the circumferential direction of the tire tread portion, the rib of the inner region sandwiched on both sides by a plurality of continuous vertical grooves, one end is the tire shoulder end portion, and the other end is the vertical portion. In a pneumatic tire having a shoulder rib sandwiched between grooves, on the circumference of at least the rib in the inner region described above, crosses between adjacent vertical grooves and divides the rib into a narrow block and a wide block. A plurality of sipes are formed as slanted sipes that are inclined in the depth direction with respect to the plane passing through the tire rotation axis and the direction from the bottom of the sipes toward the open end of the tire surface of the sipes matches the forward rotation direction of the tire. Then, a pneumatic tire in which the narrow block is projected from the wide block forming the tire surface is adopted.

That is, while the ribs are blocked by thin sipes, and the rigidity of the ribs is reduced by the inclined sipes inclined in the tire rotation direction, two or more sipes are arranged in parallel within a narrow range, and the sipes are formed between the sipes. A narrow block that protrudes slightly from the tire surface is used to take advantage of the fact that the narrow convex block that is the protruding portion has less rigidity than the wide block located between the convex blocks when touching down. In accordance with the ground contact pressure, the protruding rubber volume is bent at the tip to close the sipe, and the block is integrated with the rib by forcibly pressing.

The amount of protrusion of the convex blocks varies depending on the applied tire, but is preferably about 0.5 to 3.0 mm. If it is less than 0.5 mm, the rubber deformation at the time of grounding does not reach the point where the sipe is closed, and it becomes difficult to integrate the block with the rib. On the other hand, 3.0 mm
In the above case, the rib rigidity becomes too high and the circumferential flexibility is lost.

Regarding the depth h of the inclined sipe divided into blocks, (sipe area / length of sipe on rib surface)
Is the average depth of the sipe, and the vertical groove depth H on both sides of the rib
Is preferably about 50 to 120%. If this is less than 50%, sufficient reduction in circumferential rigidity cannot be obtained,
If it exceeds 120%, it is necessary to secure the thickness of the non-skid base, the amount of rubber increases, and there arises a problem in terms of tire durability, that is, heat resistance, and there is a problem in terms of weight increase and cost increase. . The groove width t of the inclined sipe varies depending on the tire size, but is about 0.3 to 1.
5 mm is a preferable range. The inclination angle θ inclined in the depth direction with respect to the plane passing through the tire rotation axis is preferably 15 to 40 °. These ranges are also preferable for the inclined sipe formed at the peripheral edge of the rib. The sipe length L of the inclined sipe cut in the rib width direction at the peripheral edge of the rib is preferably 3 to 8 mm.

By the way, at the rib end portions of the wide blocks located between the narrow blocks adjacent to each other in the circumferential direction, the followability to the circumferential frictional force of the end portions is further increased,
In order to reduce slippage, a sipe whose one end is open to the vertical groove can be formed, and above all, the above-mentioned inclined sipe can be adopted. Further, sipes can be formed in a narrow block to reduce the rigidity of the block. In this case, it is particularly desirable to form inclined sipes whose both ends do not open to the main groove at a location where it is necessary to reduce the rigidity. ..

On the other hand, the inclined sipe that divides the rib into blocks is closed at the position near the opening end at the time of contact with the ground, but is preferably not closed inside to ensure sufficient circumferential flexibility so that the slidable circumferential direction tends to slip. It is preferable because the ability to follow the force can be exhibited. Therefore, the width of the sipe, that is, the gap between the narrow block and the adjacent wide block may not be a uniform width, but may be increased in the vicinity of the bottom from the beginning. In this case, specifically, the average depth of the sipe from the bottom of the sipe is 1
Approximately 2/3 of the open end of the sipe up to about 3
It is desirable that the thickness is about double.

In each of the above-mentioned inventions, the inclined sipe may be formed at least at the peripheral end of the rib in the inner region, but one end is on the tire shoulder end side and the other end is a shoulder sandwiched by the vertical groove. It may be formed in a rib and is not particularly limited.

[0019]

As described above, according to the present invention, the inclined sipe that is inclined in the depth direction with respect to the plane passing through the tire rotation axis and whose direction from the bottom of the sipe to the open end of the tire surface of the sipe matches the normal rotation direction of the tire, Since it is a pneumatic tire formed at least at the peripheral edge of the rib in the inner region sandwiched between the vertical grooves, or by dividing the rib across adjacent vertical grooves to form a block, the rib rigidity is low. Because you can
Even if the frictional force of the tire in the circumferential direction with respect to the road surface is weakened, a state in which the weakened frictional force can be followed can be revealed at both ends of the rib, and the occurrence of riverwear can be prevented.

In the case of an inclined sipe in which ribs are formed into blocks, the ribs are further divided into narrow blocks and wide blocks, and the narrow blocks are projected from the wide blocks forming the tire surface. In the case of a pneumatic tire with a convex block, the narrow convex block separated by this sipe bends early at the time of contact with the ground to close this sipe, and the block is integrated as a rib, so it is made into a block. It is possible to prevent the toe-and-heel wear caused by.

[0021]

EXAMPLE FIG. 1 is a schematic view of a rib pattern showing an example of a pneumatic tire of the present invention, and FIG. 2 is II-II in FIG.
It is a line sectional view.

In the figure, 1 is a tread surface portion, 2 is a shoulder end portion, and a vertical groove 3 is formed in the tread surface portion 1 so as to be continuous in the circumferential direction. Reference numeral 4 is a rib in the inner region sandwiched between the vertical grooves 3, 3 and 5 is a shoulder rib. A large number of inclined sipes 6 whose one end is open to the vertical groove 3 are formed at small intervals at the peripheral ends of the ribs 4 and shoulder ribs 5 in the inner region.

As shown in the figure, the inclined sipe 6 is inclined in the depth direction with respect to a plane P passing through the tire rotation axis, and the sipe bottom 6
The direction from a toward the tire surface opening end 6b of the sipe is configured to coincide with the normal rotation direction R of the tire. Figure 2
In FIG. 1, h is the depth of the inclined sipe 6, t is the groove width of the inclined sipe, θ is the inclination angle with respect to the plane P passing through the tire rotation axis, and in FIG. 1, L is the sipe length of the inclined sipe 6.

When this tire is used, when the tire comes into contact with the road surface, the peripheral end of the rib 4 is prone to fall in the forward rotation direction R of the tire, so that the rib rigidity can be lowered and even if the frictional force in the peripheral direction is reduced. Even if it becomes weak, a state in which it can follow the weakened frictional force can appear at both ends of the rib, and it is possible to prevent the occurrence of river wear.

On the other hand, FIG. 3 is a schematic view of a rib pattern showing one embodiment of the pneumatic tire of the present invention related to the block type, and FIG. 4 is a sectional view taken along line IV-IV in FIG.

In this embodiment, the ribs 4 and the shoulder ribs 5 in the inner region sandwiched between the vertical grooves 3 and 3 are cut across adjacent vertical grooves 3 and 3 and between the vertical groove 3 and the shoulder end 2.
A plurality of inclined sipes 7 that divide the ribs 4 and 5 into blocks are formed at intervals. As shown in FIG. 4, the inclined sipe 7 is inclined in the depth direction with respect to the plane P passing through the tire rotation axis as in the above-described embodiment, and the direction from the sipe bottom 7a to the tire surface opening end 7b of the sipe is the tire. This is a configuration that matches the normal rotation direction R of. Reference numeral 8 is a block formed by being divided by the ribs 4 and shoulder ribs 5 in the inner region.

Therefore, even when the tire of this embodiment is in contact with the ground, the ribs 4 themselves easily fall in the forward rotation direction R of the tire, so that the rib rigidity at the peripheral edge of the rib can be lowered, and even if friction occurs in the circumferential direction. Even if the force becomes weak, a state in which the weakened frictional force can be followed can appear at the peripheral end portions of both the ribs 4 and the shoulder ribs 5 in the inner region, and the occurrence of riverwear can be prevented. ..

As shown in FIG. 5, if the width of the inclined sipe 9 is not made uniform but the sipe bottom 9a is made larger than the tire surface opening end 9b, it is closed at the position near the tire surface opening end 9a at the time of grounding. On the other hand, since they are not closed inside, sufficient flexibility in the circumferential direction can be secured, and the ability to follow the circumferential force trying to slip can be further exerted.

FIG. 6 is a schematic view of a rib pattern showing an embodiment of the pneumatic tire of the present invention relating to the convex block type, and FIG. 7 is a sectional view taken along line VII-VII in FIG.

In this embodiment, as shown in the drawing, the ribs 4 and shoulder ribs 5 in the inner region are circumferentially traversed between the adjacent vertical grooves 3 and between the vertical grooves 3 and the shoulder end portions 2, and the ribs 4,
This is the same as the above-described embodiment in that a plurality of inclined sipe 10 that divides 5 into blocks are formed at intervals. Further, the inclined sipe 10 is inclined in the depth direction with respect to a plane P passing through the tire rotation axis, and the direction from the sipe bottom 10a to the tire surface opening end 10b of the sipe is a sipe that matches the forward rotation direction R of the tire. But the same is true. However, particularly in this embodiment, the inclined sipe 10 that divides the ribs 4 and the shoulder ribs 5 in the inner region is divided into a narrow block 11 and a wide block 12, and the narrow block 11 is The difference is that it is a convex block projecting from the wide block 12 forming the tire surface.

Since this embodiment has the above-described structure, when the road surface G is grounded and a load is applied, as shown in FIG. 8, in addition to the bending of the rubber of the tread portion 1 due to the load, a convex width is applied. As a result of the narrow block 11 being strongly compressed and pushed back by a certain volume, the pushed back rubber fills the narrow groove of the sipe 10 with a strong compressive force CF. The presence of the inclined sipe 10 lowers the rigidity in the circumferential direction, whereby the followability can be improved even if the frictional force is reduced, and slippage can be prevented by the reduced frictional force.
It is possible to prevent the occurrence of river wear. In addition, since the compressive force CF of the convex narrow block 11 acts strongly even under load, the blocks 11 and 12 are integrated as a rib, the opening of the sipe 10 is prevented, and toe-and-heel wear is also prevented at the same time. be able to.

The present invention is not limited to the above embodiment.

[0033]

As described above, according to the present invention, the inclined sipes are formed at least at the peripheral end portions of the ribs in the inner region sandwiched by the vertical grooves, or the ribs are divided across adjacent vertical grooves to form a block. Since the pneumatic tire is formed with the rib, the rib rigidity can be reduced and the occurrence of river wear can be effectively prevented. In the case of a pneumatic tire that adopts an inclined sipe that divides the rib into a narrow block and a wide block, and the narrow block is a convex block protruding from the wide block that forms the tire surface Then, it is possible to effectively prevent the generation of riverwear, and at the same time, it is possible to prevent the toe-and-heel wear due to the block formation, which is a particularly remarkable effect.

[Brief description of drawings]

FIG. 1 is a schematic view of a rib pattern showing an embodiment of a pneumatic tire of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a schematic view of a rib pattern showing an example according to a block type.

4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a cross-sectional view of essential parts showing another embodiment in which the width of the bottom of the sipe is increased.

FIG. 6 is a schematic view of a rib pattern showing an example relating to a convex block type.

7 is a sectional view taken along line VII-VII in FIG.

FIG. 8 is a ground contact state diagram when a braking force is applied to the tire of the example.

[Explanation of symbols]

 1 Tread Surface 2 Shoulder End 3 Vertical Groove 4 Inner Area Rib 5 Shoulder Rib 6 Tilt Sipe 6a Sipe Bottom 6b Tire Surface Opening Edge P Plane Passing through Tire Rotation R R Positive Rotation Direction of Tire 7 Tilt Sipe 7a Sipe Bottom 7b Tire Surface open end 8 Block 10 Inclined sipe 10a Sipe bottom 10b Tire surface open end 11 Narrow block 12 Wide block

Claims (4)

[Claims] 1. A rib in an inner region sandwiched on both sides by a plurality of continuous vertical grooves in a circumferential direction of a tire tread portion, one end being a tire shoulder end, and the other end being a vertical groove. In a pneumatic tire having shoulder ribs, at least a plurality of sipes, one end of which opens into a longitudinal groove, are formed at a circumferential end portion of the rib in at least the inner region, and the sipes pass through the tire rotation axis. A pneumatic tire characterized in that it is an inclined sipe that is inclined in the depth direction with respect to a plane, and that the direction from the bottom of the sipe to the open end of the tire surface of the sipe is the same as the normal rotation direction of the tire. 2. A rib in an inner region sandwiched on both sides by a plurality of continuous vertical grooves in the circumferential direction of a tire tread portion, one end on the tire shoulder end, and the other end on the vertical groove. In the pneumatic tire having the shoulder ribs formed above, at least a plurality of sipes are formed on the circumference of at least the inner region on the circumference of the ribs that cross between adjacent vertical grooves and divide the ribs to form blocks. And, the sipe is inclined sipe inclined in the depth direction with respect to a plane passing through the tire rotation axis, and the direction from the sipe bottom toward the tire surface open end of the sipe is a sloping sipe that matches the forward rotation direction of the tire. Pneumatic tires. 3. A rib in an inner region sandwiched on both sides by a plurality of continuous vertical grooves in the circumferential direction of a tire tread portion, one end on the tire shoulder end portion, and the other end on the vertical groove. In a pneumatic tire having a shoulder rib, the sipe that crosses between adjacent vertical grooves on at least the circumference of the rib in the inner region described above and divides the rib into a narrow block and a wide block. , Inclined at a depth direction with respect to a plane passing through the tire rotation axis and formed at a plurality of intervals as inclined sipe in which the direction from the sipe bottom toward the tire surface opening end of the sipe matches the positive rotation direction of the tire, A pneumatic tire characterized in that a block having a narrow width is a convex block projecting from a block having a wide width which constitutes a tire surface. 4. Convex blocks are more than 0.
The pneumatic tire according to claim 3, which projects from the tire surface by 5 to 3 mm.