JP7306163B2 - tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to tires, in particular tires for vehicles.

In order to improve performance on ice, various tires having sipes in blocks have been proposed (see, for example, Patent Document 1 below).

JP 2018-108776 A

In general, when a large shearing force (driving force and braking force) acts on a block provided with sipes in the circumferential direction of the tire, the sipes open, stress is concentrated on the inner portion in the tire radial direction, and damage to the block is caused. tended to.

On the other hand, in order to suppress the opening of the block, it has been proposed to provide the block with a so-called 3D sipe having a sipe wall extending in a wavy shape in the depth direction of the sipe. However, the opening of the 3D sipe is excessively suppressed, the scratching effect of the sipe edge (hereinafter referred to as "edge effect") is reduced, and the on-ice performance tends to be impaired.

SUMMARY OF THE INVENTION The present invention has been devised in view of the problems described above, and a main object of the present invention is to provide a tire capable of suppressing block damage while maintaining performance on ice.

The present invention is a tire having a tread portion, the tread portion including a plurality of blocks, at least one of the blocks being formed with a plurality of sipes, the sipes being perpendicular to the longitudinal direction thereof. The cross section includes a sipe body portion extending in the tire radial direction, and a widening portion disposed radially inside the sipe body portion in the tire radial direction and having a width larger than the sipe body portion, the sipe being a first sipe. a second sipe, wherein the first sipe has a sipe wall extending planarly in the depth direction thereof, and the sipe main body portion is formed of the sipe wall; A wall defines the sipe body.

In the tire of the present invention, it is preferable that the sipe main body portion of the second sipe is formed of the sipe wall extending in a wave shape in the length direction of the second sipe.

In the tire of the present invention, it is desirable that the width of the widened portion is 4.0 times or less the width of the main body portion.

In the tire of the present invention, it is preferable that the first sipe and the second sipe each cross the blocks in the tire axial direction.

In the tire of the present invention, it is desirable that the length of the second sipe in the tire axial direction is greater than the length of the first sipe in the tire axial direction.

In the tire of the present invention, the block comprises a first sipe pair in which two of the first sipes are arranged in the tire circumferential direction, and a second sipe pair in which two of the second sipes are arranged in the tire circumferential direction. preferably included.

In the tire of the present invention, it is preferable that the block includes the first sipe pair and the second sipe pair arranged on both sides of the first sipe pair in the tire circumferential direction.

In the tire of the present invention, the block includes a first block piece partitioned between the first sipe pair and a second block piece partitioned between the second sipe pair, and the second block The axial length of the piece is preferably greater than the axial length of the first block piece.

In the tire of the present invention, the plurality of blocks includes a first block and a second block that are adjacent to each other via longitudinal grooves extending in the tire circumferential direction, and the first block and the second block include: The first sipe and the second sipe are provided to communicate with each other and extend in the axial direction of the tire, and an end portion of the first sipe provided in the first block on the longitudinal groove side is arranged in the second block. It is preferable that the second sipe is opposed to the longitudinal groove-side end of the second sipe through the longitudinal groove.

The sipe provided in the block of the tire of the present invention includes a sipe main body portion extending in the tire radial direction and a sipe main body portion disposed radially inside the sipe main body portion in the tire radial direction in a cross section perpendicular to the longitudinal direction of the sipe main body portion. and a widened portion having a width greater than. As a result, even when a large shearing force acts on the block in the tire circumferential direction, stress concentration on the radially inner portion of the tire including the bottom portion of the sipe is suppressed, and damage to the block can be suppressed.

The sipe includes a first sipe and a second sipe. The first sipe has a sipe body portion formed of a sipe wall extending flat in the depth direction, and the second sipe has a sipe body portion formed of a sipe wall extending in a wave shape in the depth direction. ing. In the second sipe, the sipe walls that face each other are engaged with each other to suppress opening of the sipe and damage to the block. In addition, since the first sipe is also provided in the block, an edge effect is produced by the opening of the first sipe, and excellent performance on ice is exhibited.

1 is a developed view of a tread portion of a tire according to one embodiment of the present invention; FIG. FIG. 2 is an enlarged view of the crown land portion of FIG. 1; 3 is an enlarged view of the blocks of FIG. 2; FIG. 4 is a cross-sectional view taken along line AA of FIG. 3; FIG. 4 is a cross-sectional view taken along the line BB of FIG. 3; FIG. It is an expansion perspective view which shows the sipe wall of a 2nd sipe.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a developed view of a tread portion 2 of a tire 1 showing one embodiment of the present invention. As shown in FIG. 1, the tire 1 of the present invention is suitably used as, for example, a pneumatic tire for heavy loads. However, the present invention is not limited to such a mode of use.

The tread portion 2 is provided with a crown main groove 3 and a shoulder main groove 4 continuously extending in the tire circumferential direction. The crown main groove 3 is arranged on the tire equator C side, for example. In this embodiment, two crown main grooves 3 are provided with the tire equator C interposed therebetween. The shoulder main groove 4 is provided between the crown main groove 3 and the tread edge Te. Note that the grooves are lightly colored in FIG. 1 so that the configuration of each part can be easily understood.

The "tread edge Te" is the maximum when the normal load is applied to the tire 1 in the normal state, which is assembled on the normal rim and filled with the normal internal pressure, and grounded on a flat surface with a camber angle of 0 degrees. This is the ground contact position on the outside in the axial direction of the tire. Unless otherwise specified, the dimensions of each part of the tire are values measured under normal conditions.

A "regular rim" is a rim defined for each tire in a standard system including the standard on which the tire is based. Then it is "Measuring Rim".

"Regular internal pressure" is the air pressure specified for each tire by each standard in the standard system including the standards on which tires are based. Maximum value described in VARIOUS COLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO.

"Normal load" is the load defined for each tire by each standard in the standard system including the standards on which tires are based. AT VARIOUS COLD INFLATION PRESSURES", and for ETRTO, it is "LOAD CAPACITY".

The crown main groove 3 and the shoulder main groove 4 extend, for example, in a zigzag shape in the tire circumferential direction.

The axial distance L1 from the tire equator C to the groove centerline of the crown main groove 3 is preferably 0.08 to 0.15 times the tread width TW, for example. The axial distance L2 from the tire equator C to the groove centerline of the shoulder main groove 4 is preferably, for example, 0.25 to 0.35 times the tread width TW. However, the arrangement of the crown main groove 3 and shoulder main groove 4 is not limited to such a range. The tread width TW is the distance in the tire axial direction between the tread edges Te, Te in the normal state.

It is desirable that the width of each main groove is, for example, 3 to 7% of the tread width TW. From the same point of view, it is desirable that the depth of each main groove is, for example, 10 to 25 mm in the case of the heavy-duty tire of this embodiment.

The tread portion 2 has land portions divided into the above-described main grooves. The land portions of this embodiment include, for example, a crown land portion 6, a middle land portion 7 and a shoulder land portion 8. As shown in FIG. A crown land portion 6 is divided between two crown main grooves 3 . The middle land portion 7 is divided between the crown main groove 3 and the shoulder main groove 4 . The shoulder land portion 8 is divided between the shoulder main groove 4 and the tread edge Te.

FIG. 2 shows an enlarged view of the crown land portion 6 as an example of the land portion. As shown in FIG. 2, the crown land portion 6 is provided with a plurality of lateral grooves 13 extending in the axial direction of the tire and longitudinal grooves 14 extending in the circumferential direction of the tire.

The lateral grooves 13 include a plurality of first lateral grooves 13A extending from one crown main groove 3 and discontinued within the crown land portion 6, and a plurality of second lateral grooves 13B extending from the other crown main groove 3 and discontinuous within the crown land portion 6. include. The first lateral groove 13A and the second lateral groove 13B are provided so as to be displaced in the tire circumferential direction.

The longitudinal groove 14 has, for example, a groove width and depth smaller than those of the crown main groove 3 . The groove width of the longitudinal groove 14 is, for example, 0.10 to 0.30 times the groove width of the crown main groove 3 . The depth of the longitudinal groove 14 is, for example, 0.10 to 0.50 times the depth of the crown main groove.

The vertical groove 14, for example, communicates between the first lateral groove 13A and the second lateral groove 13B and extends in a zigzag shape. However, it is not limited to such a mode, and the vertical groove 14 may extend linearly.

The crown land portion 6 includes a plurality of blocks 10 divided into the lateral grooves 13 and longitudinal grooves 14 described above.

An enlarged view of block 10 is shown in FIG. At least one of the blocks 10 is formed with a plurality of sipes 15, as shown in FIG. As used herein, a sipe means a cut with a width of 2.0 mm or less.

The sipe 15 includes a first sipe 16 and a second sipe 17 having different shapes. The first sipe 16 and the second sipe 17 each cross the block 10 in the tire axial direction.

The block 10 of this embodiment includes a first sipe pair 18 in which two first sipes 16 are arranged in the tire circumferential direction, and a second sipe pair 19 in which two second sipes 17 are arranged in the tire circumferential direction. include. Thereby, the block 10 includes a first block piece 18A partitioned between the first sipe pair 18 and a second block piece 19A partitioned between the second sipe pair 19 . However, the present invention is not limited to such an aspect, and one block should include at least one first sipe 16 and at least one second sipe 17 .

FIG. 4 shows a cross-sectional view of the first sipe pair 18 of FIG. 3 taken along the line AA. FIG. 5 shows a cross-sectional view of the second sipe pair 19 of FIG. 3 taken along line BB. As shown in FIGS. 4 and 5 , each sipe 15 includes a sipe main body portion 21 extending in the tire radial direction and a sipe main body portion 21 extending radially inward of the sipe main body portion 21 in a cross section orthogonal to the longitudinal direction. and a widened portion 22 having a width greater than that of the body portion 21 . As a result, even when a large shear force acts on the block 10 in the tire circumferential direction, stress concentration on the tire radially inner portion including the bottom portion of the sipe 15 is suppressed, and damage to the block 10 can be suppressed. . The widened portion 22 also improves the water absorbency of the sipe and helps to improve on-ice performance.

As shown in FIG. 4, the first sipe 16 has a sipe main body portion 21 formed of a sipe wall 20 extending in a plane in the depth direction. As shown in FIG. 5, the second sipe 17 has a sipe main body 21 formed of a sipe wall 20 extending in a wave shape in the depth direction. In addition, the second sipe 17 may extend in a zigzag shape.

In the second sipe 17 , the sipe walls 20 facing each other are engaged with each other to suppress opening of the sipe, and damage to the block 10 can be suppressed. In addition, since the block 10 is also provided with the first sipes 16, edge effects are produced by opening the first sipes 16, and excellent performance on ice is exhibited.

As shown in FIG. 4, in the first sipe 16, the width W1 of the sipe main body 21 is, for example, 0.4 to 1.0 mm. The width W2 of the widened portion 22 is, for example, preferably 1.5 times or more, more preferably 2.0 times or more, and preferably 4.0 times or less, more preferably 3.0 times the width W1 of the sipe body portion 21 . 5 times or less. The same applies to the second sipe 17 as well. As a result, the above effects can be obtained while suppressing molding defects during tire vulcanization.

As for the first sipe 16 , the sipe main body portion 21 and the widened portion 22 are connected by, for example, a curved surface 26 . A curvature radius Ra of the curved surface 26 is, for example, 10 to 25 mm. In a more desirable aspect, the radius of curvature R1 of the curved surface 26A forming the first block piece 18A is larger than the radius of curvature R2 of the opposite curved surface 26B. The radius of curvature R1 is, for example, 15-25 mm, and the radius of curvature R2 is, for example, 10-20 mm. The difference between the radius of curvature R1 and the radius of curvature R2 is, for example, 3-8 mm. This suppresses molding defects of the first block piece 18A during tire vulcanization.

The bottom of the first sipe 16 includes, for example, a first curved bottom surface 27A connected to the sipe wall forming the first block piece 18A and a second curved bottom surface 27B on the opposite side. The radius of curvature Rb of the first curved bottom surface 27A and the second curved bottom surface 27B is, for example, 0.4-0.8 mm. In a desirable aspect, the radius of curvature R3 of the first curved bottom surface 27A is smaller than the radius of curvature R4 of the second curved bottom surface 27B. The radius of curvature R3 is, for example, 0.4 to 0.6 mm, and the radius of curvature R4 is, for example, 0.6 to 0.8 mm. The difference between the radius of curvature R3 and the radius of curvature R4 is, for example, 0.2-0.4 mm. As a result, stress concentration on the bottom portion of the sipe 15 is further suppressed, and especially damage to the first block piece 18A is suppressed.

An enlarged perspective view showing the sipe wall 20 of the second sipe 17 is shown in FIG. As shown in FIG. 6 , the sipe body portion 21 of the second sipe 17 of this embodiment is formed of a sipe wall 20 that extends in a wavy shape in the longitudinal direction of the second sipe 17 . In other words, the second sipe 17 is configured as a so-called 3D sipe. Such a second sipe 17 allows the sipe walls facing each other to mesh firmly, and in addition to the above effects, helps reduce the rolling resistance of the tire.

As shown in FIG. 3, the second sipe 17 includes a plurality of inclined pieces 25 of 2.0 to 4.0 mm in the longitudinal direction of the second sipe 17 in the tread plan view. Further, the amplitude A1 of the second sipe 17 in a plan view of the tread (peak-to-peak amplitude, hereinafter the same) is, for example, 0.5 to 3.0 mm, preferably 1.0. ~2.0 mm. As a result, opening of the second sipe 17 is suppressed while molding defects during tire vulcanization are suppressed.

As shown in FIG. 5, the amplitude A2 of the second sipe 17 in the cross section perpendicular to the length direction of the second sipe 17 is, for example, 0.5 to 3.0 mm, preferably 1.0 to 1.0 mm. 2.0 mm.

As shown in FIG. 3, the first sipe pair 18 is provided in a portion of the block 10 where the width in the axial direction of the tire is small. In the present embodiment, the first block piece 18A between the first sipe pair 18 forms the smallest portion of the block 10 in the axial direction of the tire.

The second sipe pair 19 is provided in a portion of the block 10 having a greater width in the tire axial direction than the first sipe pair 18 . Thus, the length of the second sipe in the axial direction of the tire is greater than the length of the first sipe in the axial direction of the tire. In addition, the length L4 of the second block piece 19A in the axial direction of the tire is greater than the length L3 of the first block piece 18A in the axial direction of the tire. The axial length L4 of the second block piece 19A is 1.20 to 1.40 times the axial length L3 of the first block piece 18A. As a result, deformation of the wide portion of the block 10 is suppressed, and damage to the block is effectively suppressed. Such sipe placement also helps reduce the rolling resistance of the tire.

In order to further enhance the above effect, the blocks 10 of this embodiment are provided with one first sipe pair 18 arranged in the center in the tire circumferential direction and on both sides of the first sipe pair 18 in the tire circumferential direction. and second sipe pair 19 .

In the first sipe pair 18 and the second sipe pair 19, the distance L5 between two adjacent sipes is, for example, 3.0-5.0 mm, preferably 3.5-4.5 mm. As a result, the durability of the block and the performance on ice are improved in a well-balanced manner.

As shown in FIG. 2, the block 10 includes a first block 11 and a second block 12 that are adjacent to each other with a longitudinal groove 14 therebetween. The first block 11 and the second block 12 are provided with a first sipe 16 and a second sipe 17 that communicate with the longitudinal groove 14 and extend in the tire axial direction.

In a preferred embodiment, the end portion of the first sipe 16 provided in the first block 11 on the side of the flute 14 is aligned with the end portion of the second sipe 17 provided on the second block 12 on the side of the flute 14 and the end portion of the flute 14 side. facing through. Thereby, the above-mentioned effects can be further enhanced. In addition, the fact that the ends of the two sipes face each other through the longitudinal groove 14 includes a mode in which when one sipe is extended in its length direction, it partially overlaps with the end of the other sipe. .

As shown in FIG. 1, each block 10 divided into the middle land portion 7 is also provided with the first sipe 16 and the second sipe 17 described above. Moreover, the above-described configuration of the blocks 10 and the sipes 15 can be applied to the blocks 10 divided into the middle land portion 7 and the sipes 15 arranged in these blocks 10 . The tire of this embodiment is expected to further improve block durability and ice performance by applying the sipes 15 to the crown land portion 6 and the middle land portion 7 where a relatively large ground contact pressure acts. there is

Each block divided into the shoulder land portions 8 is preferably provided with only the above-described first sipes 16 . As a result, the rigidity of the blocks near the tread edge Te is moderately reduced, and the wandering performance on ice is improved.

Although the tire of one embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment described above, and can be implemented in various ways.

A heavy-duty pneumatic tire of size 11R22.5 having the basic pattern shown in FIG. As a comparative example, a tire was prototyped in which each sipe did not include a widened portion. The tire of the comparative example has the same basic pattern as shown in FIG. 1 in a tread plan view. Each test tire was tested for ice performance and block durability. Common specifications and test methods for each test tire are as follows.
Mounting rim: 7.50 x 22.5
Tire internal pressure: 800kPa
Test vehicle: 10t truck (2-D vehicle) loaded with 5t Tire mounting position: All wheels

<Ice Performance>
The time required to travel 200m on an S-intersection road consisting of continuous curves with a radius of curvature of 30m was measured. The results are indexed with the reciprocal of the time of the comparative example set to 100, and the larger the number, the better the performance on ice.

<Block durability>
The degree of damage to the block was visually evaluated when the land portion of the test vehicle was worn by 40%. The results are scored with the comparative example being 100, and the larger the number, the better the durability of the block.
The results of the tests are shown in Tables 1 and 2.

As a result of the test, it was confirmed that the tire of the example suppressed block damage while maintaining performance on ice.

2 tread portion 10 block 15 sipe 16 first sipe 17 second sipe 21 sipe body portion 22 widening portion

Claims (8)

A tire having a tread portion,
The tread portion includes a plurality of blocks,
at least one of the blocks is formed with a plurality of sipes;
The sipe has a sipe main body portion extending in the tire radial direction and a widened portion disposed radially inside the sipe main body portion in the tire radial direction and having a width larger than that of the sipe main body portion in a cross section perpendicular to the length direction of the sipe. including
The sipe includes a first sipe and a second sipe,
The first sipe has a sipe body portion formed of a sipe wall that extends planarly in the depth direction,
The second sipe has a sipe body portion formed of a sipe wall extending in a wave shape in its depth direction ,
The first sipe and the second sipe each cross the block in the tire axial direction,
tire. 2. The tire according to claim 1, wherein said sipe body portion of said second sipe is formed of said sipe wall extending in a wave shape in the length direction of said second sipe. The tire according to claim 1 or 2, wherein the width of the widened portion is 4.0 times or less the width of the sipe body portion . The tire according to any one of claims 1 to 3, wherein the axial length of the second sipe is greater than the axial length of the first sipe. 3. The block includes a first sipe pair in which two of the first sipes are arranged in the tire circumferential direction, and a second sipe pair in which two of the second sipes are arranged in the tire circumferential direction. 5. The tire according to any one of 4. The tire according to claim 5, wherein the block includes the first sipe pair and the second sipe pair arranged on both sides of the first sipe pair in the tire circumferential direction. The block includes a first block piece partitioned between the first sipe pair and a second block piece partitioned between the second sipe pair,
The tire according to claim 5 or 6, wherein the axial length of the second block piece is greater than the axial length of the first block piece. The plurality of blocks includes a first block and a second block that are adjacent to each other via longitudinal grooves extending in the tire circumferential direction,
The first block and the second block are provided with the first sipe and the second sipe that communicate with the longitudinal groove and extend in the tire axial direction,
The longitudinal groove side end of the first sipe provided in the first block faces the longitudinal groove side end of the second sipe provided in the second block via the longitudinal groove. 8. The tire of claim 7, wherein:

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