JP6949649B2 - tire - Google Patents

Description

The present invention relates to a tire capable of achieving both braking performance on an ice-snow road surface and a dry road surface.

Conventionally, a peripheral groove and a lateral groove are formed in the tread tread portion, and the land portion is divided by these peripheral grooves and the lateral groove, and a sipe extending in the tire width direction is formed in the land portion. It is known that a tire is divided into a plurality of divided land areas in the tire circumferential direction by a sipe.

JP-A-2017-128230

However, in the conventional tire, the drainage property is improved and the edge effect is exhibited by the sipe, and while the braking performance is exhibited on the icy and snowy road surface, the rigidity of the land portion is lowered, so that the braking on the dry road surface is exhibited. Performance may deteriorate.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a tire capable of achieving both braking performance on an ice-snow road surface and a dry road surface.

In order to solve the above problems, the present invention proposes the following means.
In the tire according to the present invention, a peripheral groove and a lateral groove are formed in the tread tread portion, a land portion is divided by these peripheral grooves and the lateral groove, and a sipe extending in the tire width direction is formed in the land portion. A tire in which the land portion is divided into a plurality of divided land portions in the tire circumferential direction by the sipes, and the elastic coefficient at 23 ° C. is applied to the peripheral end surface of the outer surface of the divided land portion facing the tire circumferential direction. An end rubber formed of a material having an elasticity of 3 times or more and 15 times or less of the elasticity of the material forming the land portion at 23 ° C. is arranged, and the end rubber is at least a tire on the peripheral end surface of the divided land portion. The thickness of the end rubber, which is arranged at the outer end portion in the radial direction , is the total of the divided land portion and the two end rubbers separately arranged on both peripheral end faces of the divided land portion. It is characterized in that it is 5% or more and 20% or less of the size in the tire circumferential direction.

According to the present invention, since the sipe is formed in the land portion, the rigidity of the land portion is reduced, so that the split land portion collapses at the time of touchdown, and the outer end portion in the tire radial direction in the split land portion, that is, the tread side. It is possible to generate a large stress at the corners of the tire, improve drainage and exhibit an edge effect, and it is possible to exert braking performance on icy and snowy road surfaces.
On the peripheral end surface of the divided land portion, an end rubber formed of a material having an elastic modulus at 23 ° C. of 3 times or more and 15 times or less of the elastic modulus of the material forming the land portion at 23 ° C. is arranged. Therefore, it is possible to increase the bending rigidity of the divided land portion, suppress the decrease in the rigidity of the entire land portion due to the formation of the sipe, and secure the braking performance on the dry road surface.
Since the end rubber is arranged at least at the outer end portion in the tire radial direction on the peripheral end surface of the split land portion, the stress generated at the corner portion on the tread side of the split land portion is increased, and the division is performed as described above. By increasing the bending rigidity of the land portion, the edge effect can be reliably exhibited even though the split land portion is less likely to fall when touching down.
If the elastic modulus of the material forming the end rubber at 23 ° C is less than three times the elastic modulus of the material forming the land portion at 23 ° C, the flexural rigidity of the split land portion becomes insufficient and the material on the dry road surface becomes insufficient. Braking performance cannot be ensured. If the elastic modulus of the material forming the end rubber at 23 ° C exceeds 15 times the elastic modulus of the material forming the land portion at 23 ° C, the split land portion will not easily fall over when touching down, and braking will occur on ice and snow road surfaces. It becomes difficult to demonstrate the performance.

The thickness of the end rubber is 5% or more of the size of the entire tire circumferential direction of the divided land portion and the two end rubbers separately arranged on both peripheral end faces of the divided land portion. Since it is less than% , the above-mentioned action and effect are surely achieved.
When the thickness of the end rubber becomes less than 5% of the size of the two end rubbers separately arranged on both peripheral end faces of the split land portion and the split land portion in the tire circumferential direction, the split land portion is bent. The rigidity is insufficient, and braking performance on a dry road surface cannot be ensured. If the thickness of the end rubber exceeds 20% of the size of the two end rubbers separately arranged on both peripheral end faces of the split land portion and the split land portion in the tire circumferential direction, the split land portion at the time of touchdown Not only does it become difficult for the tires to fall over, but the ground contact area of the slippery end rubber that does not easily melt the ice and snow becomes too large, making it difficult to exert braking performance on the ice and snow road surface.

Further, the end rubber may be arranged over a range of half or more in the tire radial direction on the peripheral end surface of the divided land portion.

In this case, the above-mentioned effects are surely achieved.
If the tire radial size of the end rubber is less than half the tire radial size of the peripheral end surface of the split land portion, the flexural rigidity of the split land portion is insufficient and braking performance on a dry road surface is ensured. Can't.

Further, the end rubber may be arranged on a portion of the outer surface of the divided land portion excluding the tread surface facing the outside in the tire radial direction.

In this case, since the end rubber is disposed on the outer surface of the divided land portion except for the tread surface facing outward in the tire radial direction, the above-mentioned action and effect are surely achieved. For example, if the end rubber is arranged on the tread surface of the divided land portion, the divided land portion is less likely to fall when touching down, making it difficult to exert braking performance on an ice-snow road surface, and the tread surface of the divided land portion. When the end rubbers arranged in the above are worn out, the bending rigidity of the split land portion sharply decreases, and it becomes impossible to secure the braking performance on the dry road surface.

According to the present invention, it is possible to achieve both braking performance on an ice-snow road surface and a dry road surface.

It is a plane development view of the tread tread portion of the tire which concerns on one Embodiment of this invention. FIG. 5 is a cross-sectional view taken along the line AA of the tire shown in FIG.

Hereinafter, a tire according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2.
In the present embodiment, the portion of the tread portion other than the tread tread portion 10 is not shown, but the tire 1 has a well-known structure due to general tire components. That is, the tire 1 includes a pair of bead portions, a tread portion, and a pair of sidewall portions located between the bead portion and the tread portion. The tire 1 includes a pair of bead cores, a carcass arranged between the pair of bead cores, a belt arranged on the outer peripheral side of the carcass, and a tread rubber having a tread tread portion 10.

The tread tread portion 10 is formed with a peripheral groove 11 extending in the tire circumferential direction and a lateral groove 12 extending in the tire width direction. A plurality of peripheral grooves 11 are arranged at intervals in the tire width direction, and a plurality of lateral grooves 12 are arranged at intervals in the tire peripheral direction. A plurality of land portions 13 are partitioned on the tread tread portion 10 by these peripheral grooves 11 and lateral grooves 12. The depths of the peripheral groove 11 and the lateral groove 12 are set to, for example, about 10 mm, and are equivalent to each other. The land portion 13 has a rectangular shape in which a pair of sides extend in the tire width direction and the remaining pair of sides extend in the tire circumferential direction in a plan view seen from the outside in the tire radial direction. The size of the land portion 13 in the tire width direction is, for example, about 20 mm, and the size of the land portion 13 in the tire circumferential direction is, for example, about 22 mm.

A sipe 14 extending in the tire width direction is formed on the land portion 13. The depth of the sipe 14 is, for example, about 6 mm, which is shallower than the depths of the peripheral groove 11 and the lateral groove 12. A plurality of sipes 14 are arranged on one land portion 13 at intervals in the tire circumferential direction. The sipe 14 is formed over the entire length of the land portion 13 in the tire width direction. The land portion 13 is divided into a plurality of divided land portions 15 in the tire circumferential direction by the sipe 14. The sizes of the plurality of divided land portions 15 in the tire circumferential direction are the same as each other. The plurality of divided land portions 15 are formed to have the same shape and the same size as each other.

In the present embodiment, the elastic modulus at 23 ° C. on the peripheral end surface of the outer surface of the divided land portion 15 facing the tire circumferential direction is three times or more the elastic modulus at 23 ° C. of the material forming the land portion 13. An end rubber 16 made of a material that is 15 times or less is arranged. The land portion 13 is formed of a rubber material having an elastic modulus of, for example, about 4.0 MPa at 23 ° C., and the end rubber 16 is formed of a rubber material having an elastic modulus of, for example, about 15.0 MPa at 23 ° C. Preferably, the elastic modulus of the material forming the end rubber 16 at 23 ° C. is 5 times or more and 10 times or less the elastic modulus of the material forming the land portion 13 at 23 ° C.

The end rubber 16 is arranged at least at the outer end portion in the tire radial direction on the peripheral end surface of the divided land portion 15. The end rubber 16 is arranged over a range of more than half in the tire radial direction on the peripheral end surface of the divided land portion 15.

In the illustrated example, the end rubber 16 is arranged over the entire peripheral end surface of the divided land portion 15. The end rubber 16 is arranged over the entire area of both peripheral end faces in one land portion 13. That is, of the plurality of end rubbers 16 arranged on one land portion 13, the two end rubbers 16 located at the outer ends in the tire circumferential direction have the depth of the sipe 14 as compared with the other end rubbers 16. , The length in the tire radial direction is increased by the difference between the depths of the peripheral groove 11 and the lateral groove 12. The sizes of the plurality of end rubbers 16 arranged on one land portion 13 in the tire width direction are the same as each other. Of the plurality of end rubbers 16 arranged on one land portion 13, the two end rubbers 16 located at the outer ends in the tire circumferential direction have a larger volume than the other end rubbers 16.

Here, the elastic modulus is a measured value at 23 ° C. specified in JIS K 7244. The elastic modulus is obtained by measuring the dynamic tensile storage elastic modulus E'at 23 ° C. under the conditions of an initial strain of 2%, a dynamic strain of 1%, and a frequency of 52 Hz, for example, using a spectrometer manufactured by Ueshima Seisakusho Co., Ltd. It is the value that was given.

The thickness of the end rubber 16 is 5% or more and 20% or less of the size of the entire two end rubbers 16 separately arranged on both peripheral end faces of the divided land portion 15 and the divided land portion 15 in the tire circumferential direction. It has become. For example, the thickness of the end rubber 16 is set to about 0.5 mm, and the size of the entire two end rubbers 16 separately arranged on both peripheral end faces of the divided land portion 15 and the divided land portion 15 in the tire circumferential direction. Is about 5.0 mm. The volume of the end rubber 16 is 5% or more and 20% or less of the total volume of the two end rubbers 16 separately arranged on both peripheral end faces of the divided land portion 15 and the divided land portion 15.
In one land portion 13, the gap between the end rubbers 16 facing each other in the tire circumferential direction is, for example, about 0.4 mm.

The end rubber 16 is arranged on the outer surface of the divided land portion 15 except for the tread surface 15a facing the outside in the tire radial direction. In the illustrated example, the end rubber 16 is arranged only on the peripheral end surface of the outer surface of the divided land portion 15. The end rubber 16 is connected to the side surface 15b facing the tire width direction and the tread surface 15a of the outer surface of the divided land portion 15 without a step.
The end rubber 16 may be arranged on the side surface 15b or the tread surface 15a of the divided land portion 15.

As described above, according to the tire 1 according to the present embodiment, since the sipe 14 is formed on the land portion 13, the rigidity of the land portion 13 is reduced, so that the divided land portion 15 collapses at the time of touchdown. It is possible to generate a large stress at the outer end portion in the tire radial direction of the divided land portion 15, that is, the corner portion on the tread surface 15a side, and the improvement of drainage property and the edge effect are exhibited, and the braking performance on the ice and snow road surface is exhibited. Can be demonstrated.

An end rubber 16 formed of a material having an elastic modulus at 23 ° C. of 3 times or more and 15 times or less of the elastic modulus of the material forming the land portion 13 at 23 ° C. is arranged on the peripheral end surface of the divided land portion 15. Therefore, it is possible to increase the bending rigidity of the divided land portion 15, the decrease in the rigidity of the entire land portion 13 due to the formation of the sipe 14 is suppressed, and the braking performance on the dry road surface is ensured. Can be done.
Since the end rubber 16 is arranged at least at the outer end portion in the tire radial direction on the peripheral end surface of the divided land portion 15, the stress generated at the corner portion on the tread surface 15a side of the divided land portion 15 is increased, and the stress generated in the corner portion on the tread surface 15a side of the divided land portion 15 is increased. By increasing the bending rigidity of the split land portion 15 as described above, the edge effect can be reliably exhibited even though the split land portion 15 is less likely to fall when touching down.

The thickness of the end rubber 16 is 5% or more and 20% or less of the size of the entire two end rubbers 16 separately arranged on both peripheral end faces of the divided land portion 15 and the divided land portion 15 in the tire circumferential direction. Therefore, the above-mentioned action and effect are surely achieved.
When the thickness of the end rubber 16 becomes less than 5% of the size of the two end rubbers 16 separately arranged on both peripheral end faces of the divided land portion 15 and the divided land portion 15 in the tire circumferential direction, the divided rubber 16 is divided. The bending rigidity of the land portion 15 is insufficient, and the braking performance on a dry road surface cannot be ensured. When the thickness of the end rubber 16 exceeds 20% of the size of the two end rubbers 16 separately arranged on both peripheral end faces of the divided land portion 15 and the divided land portion 15 in the tire circumferential direction, the ground contact is made. Not only is it difficult for the split land portion 15 to fall down, but also the ground contact area of the slippery end rubber 16 that is difficult to melt the ice and snow becomes too wide, making it difficult to exert braking performance on the ice and snow road surface.

Since the end rubber 16 is arranged over a range of more than half in the tire radial direction on the peripheral end surface of the divided land portion 15, the above-mentioned action and effect are surely achieved.
If the tire radial size of the end rubber 16 is less than half the tire radial size of the peripheral end surface of the split land portion 15, the bending rigidity of the split land portion 15 is insufficient and the braking performance on a dry road surface is insufficient. Cannot be secured.

Since the end rubber 16 is disposed on the outer surface of the divided land portion 15 except for the tread surface 15a facing outward in the tire radial direction, the above-mentioned action and effect are surely achieved. For example, if the end rubber 16 is arranged on the tread surface 15a of the split land portion 15, the split land portion 15 is less likely to fall down at the time of touchdown, and it becomes difficult to exert braking performance on an ice-snow road surface, and the split land portion 15 is also divided. When the end rubber 16 arranged on the tread surface 15a of the land portion 15 is worn out, the bending rigidity of the split land portion 15 sharply decreases, and the braking performance on the dry road surface cannot be ensured.

Next, the verification test of the action and effect described above will be described.

As an embodiment, the tire 1 shown in FIG. 1 is adopted, as a conventional example 1, a configuration in which the tire 1 of the embodiment does not have the sipe 14 and the end rubber 16 is adopted, and as the conventional example 2, the tire 1 of the embodiment is adopted. In, a configuration having a sipe 14 and no end rubber 16 was adopted.
In both Examples 1 and 2, the size was 195 / 65R15, the vehicle was mounted on a vehicle with an air pressure of 200 kPa, and the braking performance was evaluated on a dry road surface, an ice road surface, and a snow road surface, respectively.
The evaluation measures the braking distance (L) when the road surface is fully braked while traveling straight at speeds (v) of 100 km / h, 40 km / h, and 30 km / h, and the traveling speed (v) and braking are measured. ^{The average deceleration (v 2} / 2L) calculated from the distance (L) was used. Specifically, it is evaluated by an index with the average deceleration obtained when the tire of the conventional example 1 having no sipe 14 and the end rubber 16 is mounted and the vehicle travels straight on a dry road surface at a speed of 100 km / h as 100. bottom. In this case, the larger the value, the better the braking performance.
As a result, as shown in Table 1, it was confirmed that the tire 1 of the embodiment can achieve both braking performance on an ice-snow road surface and a dry road surface.

The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, in the above-described embodiment, the land portion 13 is configured to have a rectangular shape when viewed from the outside in the tire radial direction, but the present invention is not limited to this, and the land portion 13 may be appropriately changed, for example, to have a triangular shape.
In the above embodiment, the plurality of divided land portions 15 are formed to have the same shape and the same size as each other, but the plurality of divided land portions may have different shapes and different sizes.
In the above embodiment, the sipe 14 is formed over the entire length of the land portion 13 in the tire width direction, but the end portion of the sipe 14 in the tire width direction may be located inside the land portion 13 in the tire width direction.

In addition, it is possible to replace the components in the embodiment with well-known components as appropriate without departing from the spirit of the present invention, and the above-mentioned modifications may be appropriately combined.

1 Tire 10 Tread tread 11 Circumferential groove 12 Horizontal groove 13 Land 14 Sipe 15 Divided land 15a Tread 16 End rubber

Claims (3)

A peripheral groove and a lateral groove are formed on the tread tread, a land portion is divided by these peripheral grooves and the lateral groove, a sipe extending in the tire width direction is formed on the land portion, and the land portion is tired by the sipe. A tire that is divided into multiple land areas in the circumferential direction.
A material having an elastic modulus at 23 ° C. of the outer surface of the divided land portion facing the tire circumferential direction, which is 3 times or more and 15 times or less the elastic modulus at 23 ° C. of the material forming the land portion. The end rubber formed by
The end rubber is arranged at least at the outer end portion in the tire radial direction on the peripheral end surface of the divided land portion .
The thickness of the end rubber
With the divided land area
A tire characterized in that the size of the two end rubbers separately arranged on both peripheral end surfaces of the divided land portion and the overall tire circumferential size is 5% or more and 20% or less. The tire according to claim 1, wherein the end rubber is arranged over a range of more than half in the tire radial direction on the peripheral end surface of the divided land portion. The tire according to claim 1 or 2 , wherein the end rubber is disposed on a portion of the outer surface of the divided land portion excluding a tread surface facing outward in the tire radial direction.

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