JP2019162989A - tire - Google Patents

Abstract

To provide a tire capable of securing on-snow performance of an abrasion end period of a land part while maintaining abrasion resistance performance of the land part when the tire is new.SOLUTION: A tire comprises a tread part. The tread part comprises a groove and a land part 4 partitioned into the groove. The land part 4 is provided with semi-open siping 20. The semi-open siping 20 comprises a first end 21 communicating with the groove, a second end 22 positioned in the land part 4 and the siping length up to the second end 22 from the first end 21. The semi-open siping 20 includes first siping 25 larger in the siping length L2 at a siping bottom 23 than the siping length L1 on a ground plane of the land part 4.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a tire, and more particularly to a tire having a tread portion provided with a semi-open sipe.

  Conventionally, a tire having a sipe provided on a land portion of a tread portion has been proposed in order to increase a frictional force on an icy and snowy road. On the other hand, the tire has a tendency that the rigidity of the land portion is reduced by sipe and the land portion is easily worn. In particular, SUV and the like have a large vehicle body weight, and tires equipped on this type of vehicle are required to have high wear resistance.

  Patent Document 1 below proposes a pneumatic tire in which a semi-open sipe is provided in a crown land portion. Since one end of the semi-open sipe is located in the land portion, the wear resistance performance of the land portion can be maintained as compared with a full open sipe whose both ends communicate with the groove.

JP 2013-116708 A

  However, even in the semi-open sipe, the performance on ice and snow tended to be greatly impaired at the end of land wear. Further, when the tire is new, the sipe is likely to open excessively and the land portion may be easily worn.

  The present invention has been devised in view of the actual situation as described above, and it is a main object of the present invention to provide a tire that can ensure the performance on land and snow at the end of wear of the land while maintaining the wear resistance when the tire is new. It is said.

  The present invention is a tire having a tread portion, wherein the tread portion has a groove and a land portion divided into the grooves, and the land portion is provided with a semi-open sipe, and the semi-open The sipe has a first end communicating with the groove, a second end located in the land portion, and a sipe length from the first end to the second end, and the semi-open sipe has the land A first sipe in which the sipe length at the sipe bottom is larger than the sipe length at the ground contact surface of the part.

  In the tire of the present invention, it is preferable that the sipe length of the first sipe gradually increases from the ground contact surface of the land portion to the sipe bottom.

  In the tire according to the aspect of the invention, it is preferable that the first sipe is disposed on one side of the land portion in the tire axial direction and on the other side of the land portion in the tire axial direction.

  In the tire of the present invention, it is preferable that the first sipe is inclined in the same direction with respect to the tire axial direction.

  In the tire according to the present invention, it is preferable that the first sipe on the one side is disposed on an extension line of the first sipe on the other side or with a deviation of ± 2 mm from the extension line. .

  In the tire according to the present invention, the semi-open sipe has a change from the sipe length at the ground contact surface of the land portion to the sipe length at the sipe bottom smaller than that of the first sipe, or It is desirable to include a second sipe that is zero.

  In the tire of the present invention, it is preferable that the tire includes a portion where the first sipe and the second sipe are alternately provided.

  In the tire of the present invention, the land portion is a block, the first sipe is disposed on both sides of the block in the tire circumferential direction, and the second sipe is provided between the first sipe. It is desirable.

  In the tire of the present invention, it is preferable that the sipe length of the first sipe at the ground contact surface is smaller than the sipe length of the second sipe at the ground contact surface.

  In the tire according to the present invention, the first sipe is inclined in a first direction with respect to a tire normal line and the second end is with respect to the tire normal line in a front view orthogonal to the sipe center plane. In this case, it is desirable to incline in the second direction opposite to the first direction.

  In the tire of the present invention, the land portion is a block, and the block is provided with a third sipe that crosses the block in the tire axial direction, and the third sipe is a pair disposed on both sides in the tire axial direction. It is preferable that the first portion and a second portion extending obliquely between the pair of first portions have a depth smaller than the maximum depth of the first portion.

  In the tire according to the present invention, the first sipe has a pair of linear portions extending linearly and an arc portion bent in a semicircular shape between the pair of linear portions in a plan view of the tread portion. Is desirable.

  In the tire according to the present invention, the sipe length at a depth of 80% of the maximum depth of the first sipe is 1.50 to 2.50 times the sipe length at the contact surface of the land portion. Is desirable.

  The semi-open sipe provided in the land portion of the tire of the present invention has a first end communicating with the groove, a second end located in the land portion, and a sipe length from the first end to the second end. ing. The semi-open sipe includes a first sipe in which the sipe length at the sipe bottom is larger than the sipe length at the ground contact surface of the land.

  Since the first sipe has a relatively small sipe length when the tire is new, it is possible to suppress excessive opening of the sipe and maintain the wear resistance performance of the land portion. Further, when the tire is new, a groove having a sufficient depth together with the first sipe can improve the performance on ice and snow. On the other hand, since the first sipe has a large sipe length at the bottom of the sipe, high performance on ice and snow can be exhibited even at the end of wear of the land portion.

It is an expanded view of the tread part of the tire of one embodiment of the present invention. (A) is an enlarged view of the block of FIG. 1, (b) is the sectional view on the AA line of (a). (A) is an enlarged view of the block of other embodiment of this invention, (b) is the BB sectional drawing of (a). (A) is an enlarged view of the block of other embodiment of this invention, (b) is CC sectional view taken on the line of (a). It is an enlarged view of the block of other embodiment of this invention. (A) is an enlarged view of the block provided in the tread part of the tire of a comparative example, (b) is the DD sectional view taken on the line of (a).

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a development view of a tread portion 2 of a tire 1 showing an embodiment of the present invention. The tire 1 of the present embodiment is used, for example, as a winter pneumatic tire, and is particularly preferably used for SUV and the like. However, it is not limited to such an aspect, The tire of this invention may be used as a heavy load tire, for example.

  As shown in FIG. 1, the tread portion 2 of the tire 1 has a groove 3 and a land portion 4 divided into the grooves 3. The groove 3 includes, for example, a plurality of main grooves 5 that continuously extend in the tire circumferential direction, and lateral grooves 6 that extend between the main grooves 5 in the tire axial direction.

  The main groove 5 includes, for example, a shoulder main groove 7 disposed closest to the tread end Te between the tire equator C and the tread end Te, and a crown provided between the shoulder main groove 7 and the tire equator C. Main groove 8 included.

  In the case of a pneumatic tire, the tread end Te is a contact position on the outermost side in the tire axial direction when a normal load is applied to the tire 1 in a normal state and the tire 1 contacts the plane with a camber angle of 0 °. The normal state is a state in which the tire is assembled on the normal rim and is filled with the normal internal pressure, and further, there is no load. In the present specification, unless otherwise specified, the dimensions and the like of each part of the tire are values measured in a normal state.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, “Standard Rim” for JATMA, “Design Rim” for TRA, and “ETRTO” If there is "Measuring Rim".

  “Regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. “JAMATA” is the “highest air pressure”, TRA is the table “TIRE LOAD LIMITS AT” The maximum value described in “VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” for ETRTO.

  “Regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. “JATMA” is “Maximum load capacity”, TRA is “TIRE LOAD LIMITS” The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “LOAD CAPACITY” in the case of ETRTO.

  The groove width W1 of each main groove 5 is preferably 3.0 to 6.0% of the tread width TW, for example. The tread width TW is a distance in the tire axial direction from one tread end Te to the other tread end Te in the normal state. The groove depth of each main groove 5 is preferably 5 to 15 mm, for example.

  The lateral groove 6 includes, for example, a shoulder lateral groove 9 that communicates between the tread end Te and the shoulder main groove, a middle lateral groove 10 that communicates between the shoulder main groove 7 and the crown main groove 8, and both sides of the tire equator C. And a transverse crown groove 11 communicating between the two arranged crown main grooves 8.

  The land portion 4 includes, for example, a plurality of blocks 12 divided into a main groove 5 and a lateral groove 6. The block 12 includes, for example, a shoulder block 13, a middle block 14, and a crown block 15. The shoulder block 13 is divided into shoulder lateral grooves 9 between the shoulder main groove 7 and the tread end Te, for example. The middle block 14 is divided into middle lateral grooves 10 between the shoulder main groove 7 and the crown main groove 8, for example. The crown block 15 is divided into, for example, crown transverse grooves 11 between the two crown main grooves 8.

  The land portion 4 is provided with a semi-open sipe 20. In this specification, “sipe” means a notch having a width of less than 1.5 mm. Further, “semi-open sipe” means a sipe having one end communicating with the groove and the other end interrupted in the land.

  FIG. 2A is an enlarged view of the block 12 as a diagram showing an embodiment of the semi-open sipe 20. The block 12 shown in FIG. 2A is a middle block 14. FIG. 2B shows a cross-sectional view taken along line AA of the semi-open sipe 20 of FIG. As shown in FIG. 2A, the semi-open sipe 20 includes a first end 21 communicating with the groove 3 and a second end 22 located in the land portion 4 (in the block 12 in FIG. 2A). Have Further, as shown in FIG. 2B, the semi-open sipe 20 has a sipe length from the first end 21 to the second end 22. The semi-open sipe 20 is not limited to an aspect that extends in the tire axial direction and communicates with the main groove 5, but may be one that communicates with the lateral groove 6 and extends in the tire circumferential direction, for example.

  The semi-open sipe 20 includes a first sipe 25 having a sipe length L2 at the sipe bottom 23 that is larger than the sipe length L1 at the ground contact surface of the land portion 4. Since the first sipe 25 has a relatively small sipe length when the tire is new, it is possible to suppress excessive opening of the sipe and maintain the wear resistance performance of the land portion. Further, when the tire is new, a groove having a sufficient depth together with the first sipe 25 can improve the performance on ice and snow. On the other hand, since the first sipe 25 has a large sipe length at the sipe bottom, the first sipe 25 can exhibit high performance on ice and snow even at the end of wear of the land portion.

  It is desirable that the sipe length of the first sipe 25 is gradually increased from the ground contact surface 4s of the land portion 4 to the sipe bottom 23, for example. Such a first sipe 25 can suppress a sudden change in performance on ice and snow due to the progress of wear.

  In the first sipe 25, for example, in a front view orthogonal to the sipe center plane, the first end 21 is inclined in the first direction with respect to the tire normal, and the second end 22 is in the first direction with respect to the tire normal. It is desirable to incline in the second direction opposite to the above. Accordingly, the second end 22 is inclined in a direction away from the first end 21 from the ground surface 4s toward the sipe bottom 23.

  The second end 22 is preferably inclined at a constant angle from the ground contact surface 4s to the sipe bottom 23, for example. The angle θ1 of the second end 22 with respect to the tire normal is preferably 10 to 20 °, for example. Such a second end 22 can exhibit excellent performance on ice and snow while maintaining wear resistance when a tire is new.

  The sipe length L1 at the ground contact surface 4s of the land portion 4 is preferably 0.15 to 0.30 times the width W2 of the block 12, for example. The sipe length L3 at the depth d3 that is 80% of the maximum depth d2 of the first sipe 25 is preferably, for example, 0.35 to 0.45 times the width of the block 12 at the depth d3. Further, the sipe length L3 at a depth of 80% of the maximum depth of the first sipe 25 is desirably 1.50 to 2.50 times the sipe length L1 at the ground contact surface 4s. Such a first sipe 25 can exhibit excellent performance on ice and snow even when the block 12 is worn. The maximum depth d2 of the first sipe 25 is preferably 0.2 to 0.8 times the depth d1 of the main groove 5.

  As shown in FIG. 2A, the first sipe 25 of the present embodiment is desirably arranged on one side of the block 12 in the tire axial direction and on the other side of the block 12 in the tire axial direction. . Such an arrangement of the first sipe 25 can suppress uneven wear of the block 12. In a more desirable mode, a plurality of first sipes 25 are provided on each of the one side and the other side. In the present embodiment, three first sipes 25 are provided on each of the one side and the other side.

  From the same viewpoint, it is desirable that the first sipes 25 arranged in the block 12 are inclined in the same direction with respect to the tire axial direction. In a desirable mode, the first sipes 25 are arranged in parallel to each other.

  The first sipe 25 on the one side is preferably disposed on an extension line extending in the length direction of the first sipe 25 on the other side or with a deviation of ± 2 mm from the extension line. . Such a first sipe 25 can further suppress uneven wear of the block 12.

  FIG. 3 (a) shows an enlarged view of the block 12 of another embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the element which is common in the above-mentioned embodiment, and description here is abbreviate | omitted. As shown in FIG. 3A, the block 12 of this embodiment is provided with the first sipe 25 described above and a second sipe 26 different from the first sipe 25.

  FIG. 3B shows a cross-sectional view of the second sipe 26 taken along the line BB. As shown in FIG. 3 (b), the second sipe 26 has a change from the sipe length L 1 at the ground contact surface 4 s of the land portion 4 to the sipe length L 2 at the sipe bottom 23. It is smaller or zero. In the present embodiment, the second end 22 extends parallel to the tire normal. In this embodiment, the first sipe 25 is substantially the same as the shape described above. The second sipe 26 can ensure the rigidity of the block without excessively increasing the sipe length when the block is worn to some extent.

  As shown in FIG. 3A, in this embodiment, the first sipe 25 and the second sipe 26 are included alternately. More specifically, the first sipes 25 are disposed on both sides of the block 12 in the tire circumferential direction, and the second sipes 26 are provided between the two first sipes 25. Such a sipe arrangement can suppress wear of the central portion of the block 12 in the tire circumferential direction.

  The sipe length at the ground contact surface of the first sipe 25 is preferably smaller than the sipe length at the ground contact surface of the second sipe 26. As a desirable mode, in this embodiment, when the block is worn to 80% of the maximum depth of the first sipe 25, the sipe length of the first sipe 25 and the sipe length of the second sipe 26 become equal.

  FIG. 4 (a) shows an enlarged view of the block 12 of another embodiment of the present invention. As shown in FIG. 4A, the block 12 is provided with a third sipe 27 that crosses the block in the tire axial direction.

  The third sipe 27 includes, for example, a pair of first portions 28 disposed on both sides in the tire axial direction, and a second portion 29 extending obliquely between the pair of first portions 28. The block 12 is provided with two first sipes 25 on one side or the other side in the tire circumferential direction of each first portion 28. For example, the first portion 28 has the same depth as the first sipe 25 described above.

  The pair of first portions 28 are inclined in the same direction with respect to the tire axial direction. For example, the second portion 29 is inclined in the same direction as the first portion 28 and is inclined at a larger angle than the first portion 28 with respect to the tire axial direction.

  FIG. 4B is a cross-sectional view taken along line CC of the second portion 29 of the first sipe 25 and the third sipe 27 provided in the block 12. As shown in FIG. 4B, the second portion 29 has a depth smaller than that of the first sipe 25, for example. Further, it is desirable that the second portion 29 has a depth smaller than the maximum depth of the first portion 28, for example. Such a third sipe 27 increases the rigidity of the block 12 in a state where the second portion 29 is worn out and the second portion 29 disappears while the second portion 29 exhibits better performance on ice and snow when the tire is new. As a result, excellent wear resistance performance can be exhibited.

  FIG. 5 shows an enlarged view of the block 12 of another embodiment of the present invention. As shown in FIG. 5, the first sipe 25 of this embodiment includes a pair of linear portions 31 extending linearly and an arc portion 32 bent in a semicircular shape between the pair of linear portions 31. The radius of curvature of the arc portion 32 is preferably, for example, 1.0 to 2.5 mm. Such a sipe blade of a vulcanization mold for forming the first sipe 25 has high durability because a portion for forming the arc portion 32 is bent in an arc shape. For this reason, the bending and bending of the sipe blade at the time of vulcanization molding can be suppressed. Further, when the sipe walls facing each other come into contact with each other, the arc portions 32 are engaged with each other and the deformation of the block 12 in the tire axial direction can be suppressed. For this reason, abrasion resistance performance is improved.

  The configuration of the block 12 of each embodiment described above may be applied to any of the crown block 15, the middle block 14, and the shoulder block 13.

  The tire having the first sipe 25 described above can be obtained by hand-cutting each land portion at least. Further, when the angle of the second end 22 is relatively small, the first sipe 25 can be vulcanized with a sipe blade fixed to the vulcanization mold. When the angle of the second end 22 is large, for example, the first sipe 25 can be vulcanized by using a vulcanization mold having a movable sipe blade. The movable sipe blade can be moved to the rib side forming the main groove when the vulcanizing mold is removed from the tire, and the first sipe 25 can be formed without damaging the block.

  As mentioned above, although the tire of one embodiment of the present invention was explained in detail, the present invention is not limited to the above-mentioned specific embodiment, and can be carried out by changing to various modes.

Tires of size 275 / 55R20 having the basic pattern of FIG. 1 and having the blocks shown in FIGS. 2 to 5 as crown blocks and middle blocks were made on the basis of the specifications in Table 1. As a comparative example, as shown in FIGS. 6A and 6B, a block a in which a semi-open sipe b having a sipe length c on the ground plane larger than a sipe length d on the sipe bottom is arranged. A tire with a prototype was made. Each tire has substantially the same specifications except for the configuration shown in Table 1. Each tire was tested for performance on snow and ice and new wear resistance when the tire was new and worn. The common specifications and test methods for each tire are as follows.
Block width: 40mm
Main groove depth: 12mm
Wearing rim: 20 × 9J
Tire internal pressure: 250kPa
Test vehicle: 4600cc four-wheel drive vehicle Test tire mounting position: All wheels

<Performance on ice and snow when tires are new and worn>
When the tire was new and the tire was worn, the performance when the test vehicle was running on an icy and snowy road was evaluated based on the driver's sensuality. In this test, when the tire is worn, the land portion is worn down to a depth of 80% of the first sipe. A result is a score which makes a comparative example 100, and shows that performance on ice and snow is excellent, so that a numerical value is large.

<Abrasion resistance>
After running 12,000 miles on the test vehicle, the block height from the bottom of the main groove to the ground contact surface of the block was measured. A result is an index which makes the block height of a comparative example 100, and shows that abrasion resistance performance is excellent, so that a numerical value is large.

  As a result of the test, it was confirmed that the tires of the examples improved the performance on ice and snow when the tires were worn while maintaining the wear resistance performance of the land portion.

2 Tread part 3 Groove 4 Land part 20 Semi-open sipe 21 1st end 22 2nd end 23 Sipe bottom 25 1st sipe L1 Sipe length in the ground plane L2 Sipe length in sipe bottom

Claims (13)

A tire having a tread portion,
The tread portion has a groove and a land portion divided into the grooves,
In the land part, a semi-open sipe is provided,
The semi-open sipe has a first end communicating with the groove, a second end located in the land portion, and a sipe length from the first end to the second end,
The semi-open sipe includes a first sipe in which the sipe length at the sipe bottom is larger than the sipe length at the ground contact surface of the land portion.
tire.   The tire according to claim 1, wherein the sipe length of the first sipe gradually increases from a contact surface of the land portion to the sipe bottom.   The tire according to claim 1 or 2, wherein the first sipes are arranged on one side of the land portion in the tire axial direction and on the other side of the land portion in the tire axial direction.   The tire according to claim 3, wherein the first sipes are inclined in the same direction with respect to the tire axial direction.   The said 1st sipe of the said one side is arrange | positioned with the deviation | shift of +/- 2mm with respect to the extension line of the said 1st sipe of the said other side, or the said extension line. tire.   The semi-open sipe is a second sipe in which the change from the sipe length at the land contact surface to the sipe length at the bottom of the sipe is smaller or zero than that of the first sipe. The tire according to claim 1, comprising:   The tire according to claim 6, including a portion in which the first sipe and the second sipe are alternately provided.   The land portion is a block, the first sipe is disposed on both sides of the block in the tire circumferential direction, and the second sipe is provided between the first sipe. The described tire.   The tire according to claim 8, wherein a sipe length of the first sipe at the contact surface is smaller than the sipe length of the second sipe at the contact surface.   The first sipe is inclined in a first direction with respect to a tire normal, and the second end is in the first direction with respect to the tire normal in a front view perpendicular to the sipe center plane. The tire according to any one of claims 1 to 9, which is inclined in a reverse second direction. The land portion is a block, and the block is provided with a third sipe that crosses the block in the tire axial direction,
The third sipe includes a pair of first portions disposed on both sides in the tire axial direction, and a second portion extending obliquely between the pair of first portions,
The tire according to any one of claims 1 to 10, wherein the second portion has a depth smaller than a maximum depth of the first portion.   The first sipe has a pair of linear portions extending linearly and an arc portion bent in a semicircular shape between the pair of linear portions in a plan view of the tread portion. The tire according to any one.   13. The sipe length at a depth of 80% of the maximum depth of the first sipe is 1.50 to 2.50 times the sipe length at a ground contact surface of the land portion. The tire according to any one of the above.

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