JP7290056B2 - tire - Google Patents

Description

The present invention relates to tires.

Patent Literature 1 listed below describes a pneumatic tire for running on rough terrain in which a plurality of blocks are arranged in the tread portion. The block is provided with a cut portion comprising a pair of first sipes extending from the edge of the block and a second sipe connecting the first sipes. Thereby, the block includes a sub-part divided inside the notch and a main part divided outside the notch.

Japanese Patent No. 5890862

In the above pneumatic tire, for example, the edge effect of the main portion and the gripping force of the tread surface of the block tend to be small, and there is room for improvement in terms of traction performance and slide control performance.

The present invention has been devised in view of the actual situation as described above, and a main object of the present invention is to provide a tire with improved traction performance and slide control performance.

The present invention is a tire including a tread portion, the tread portion being formed with first blocks, the first blocks having a pair of ends extending from block edges and terminating in the tread surface. Surrounded by a first sipe, a second sipe joining between the ends of each first sipe, the pair of first sipes, the second sipe, and the block edge extending between the pair of first sipes A first portion and a second portion surrounding the first portion from three sides, the first portion projecting outward in the tire radial direction more than the second portion, and the center portion of the tread surface of the first portion is the peripheral edge. It is located radially inward of the part.

In the tire according to the present invention, it is preferable that the block height of the central portion is 80% or more of the block height of the second portion.

In the tire according to the present invention, it is preferable that the area of the peripheral portion is 30% or less of the area of the first portion.

In the tire according to the present invention, it is preferable that the area of the central portion is 50% or less of the area of the first portion.

In the tire according to the present invention, it is preferable that the central portion is formed with a curved surface.

In the tire according to the present invention, it is desirable that the angle between the central portion and the peripheral portion is 10 to 70° in a cross section perpendicular to the longitudinal direction of the first sipe.

In the tire according to the present invention, it is desirable that the rubber hardness of the first block is 70 or more.

In the tire of the present invention, the first block includes a pair of first sipes extending from the block edge and having ends terminating in the tread, and a second sipe joining between the ends of each of the first sipes. . The first block includes a first portion surrounded by the pair of first sipes, the second sipes, and the block edge extending between the pair of first sipes, and the first portion surrounding the first portion from three sides. Includes a second portion.

The first portion protrudes radially outward from the second portion, and the central portion of the tread surface of the first portion is located radially inward of the peripheral portion. Since such a first portion can be deformed toward the edge of the block, edge effect and grip effect are enhanced. Further, since a large ground contact pressure acts on the peripheral portion positioned radially outward of the central portion, the peripheral portion deforms inward in the tire radial direction, and both the central portion and the peripheral portion contact the ground. Moreover, since the center portion and the peripheral edge portion are crushed inward in the tire radial direction due to the ground contact at this time, the second portion is also grounded. As a result, the grip effect of the tread surface of the first block is maintained at a high level, and the edge effect of the block edge of the second portion is exhibited. Therefore, the tire of the present invention has excellent traction performance and slide control performance.

It is a perspective view of the 1st block of this embodiment. It is a top view of a 1st block. (a) is a cross-sectional view taken along line AA of FIG. 1, and (b) is a cross-sectional view along line BB of FIG. It is a top view of a 1st block. It is a perspective view of the 1st block of other embodiments. (a) to (c) are cross-sectional views of the first block of still another embodiment. FIG. 3 is a development view of the tread portion of the embodiment;

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view of the first block 3 formed on the tread portion 2 of the tire 1 of this embodiment. FIG. 2 is a plan view of the first block 3. FIG. In this embodiment, as a preferred aspect, for example, a first block 3 provided in a tire 1 for an off-road motorcycle used in motocross competitions is shown. Such a tire 1 can run, for example, on asphalt road surfaces in addition to uneven terrain such as muddy ground and gravel roads. It should be noted that the present invention can also be applied to tires 1 of other categories including, for example, passenger car and heavy duty tires.

As shown in FIGS. 1 and 2, the first block 3 includes a tread surface 3a that contacts the road surface when grounding, a block wall 3b that connects the tread surface 3a and the groove bottom 2a of the tread portion 2, 3b and a block edge 3c formed as an edge.

The first block 3 of this embodiment includes a pair of first sipes 4, 4 having ends 4e extending from the block edge 3c and terminating in the tread surface 3a, and a and a second sipe 5 that joins.

Thereby, in this embodiment, the first block 3 is surrounded by a pair of first sipes 4, 4, a second sipe 5, and a block edge 3c extending between the pair of first sipes 4, 4. It is formed including a portion 6 and a second portion 7 surrounding the first portion 6 from three sides.

3(a) is a cross-sectional view taken along line AA of FIG. 1, and FIG. 3(b) is a cross-sectional view taken along line BB of FIG. is. As shown in FIG. 3 , the first portion 6 protrudes further outward in the tire radial direction than the second portion 7 in this embodiment. Further, in the tread surface 6 a of the first portion 6 , the central portion 9 is located radially inward of the peripheral edge portion 10 . Since such a first portion 6 can be deformed toward the block edge 3c side, edge effect and grip effect are enhanced. Further, since a large ground contact pressure acts on the peripheral portion 10 positioned radially outward of the central portion 9, the peripheral portion 10 deforms inward in the tire radial direction, and both the central portion 9 and the peripheral portion 10 are grounded. Further, due to the ground contact at this time, the central portion 9 and the peripheral edge portion 10 are crushed inward in the tire radial direction, and the second portion 7 is also grounded. As a result, the gripping force of the tread surface 3a of the first block 3 is maintained high, and the edge effect of the second block edge 7c, which is the block edge of the second portion 7, is exhibited. Therefore, the tire 1 of this embodiment has excellent traction performance and slide control performance.

As shown in FIGS. 1 and 2, the tread surface 3a of the first block 3 is, for example, substantially rectangular, specifically trapezoidal. Note that the tread surface 3a is not limited to such a form, and various forms such as a rectangular shape and a hexagonal shape can be adopted.

The block edge 3 c of the first block 3 includes a first block edge 6 c formed on the first portion 6 and a second block edge 7 c formed on the second portion 7 in this embodiment.

The first block edge 6c of this embodiment includes a pair of first edge portions 11a extending along the first sipe 4, a second edge portion 11b extending along the second sipe 5, and a A third edge 11c is formed. The second edge portion 11b and the third edge portion 11c join the ends of the first edge portion 11a.

The second block edge 7c of the present embodiment includes a pair of fourth edge portions 12a, 12a connected to the first sipe 4, a pair of fifth edge portions 12b, 12b extending from the outer ends of the fourth edge portion 12a, and a pair of and a sixth edge 12c connecting between the fifth edges 12b. The sixth edge 12c extends, for example, along the second edge 11b, specifically parallel to the second edge 11b. Note that the first block edge 6c and the second block edge 7c are not limited to such a form.

The first portion 6 is formed to protrude outward beyond the fourth edge portion 12a. Thereby, the block wall 13a connected to the third edge portion 11c is arranged outside the block wall 13b connected to the fourth edge portion 12a. Such a first block 3 enhances traction on muddy ground.

The first sipe 4 extends, for example, to form a bent portion 4a. In this embodiment, the first sipe 4 has one bent portion 4a that protrudes toward the outside of the first block 3 and extends linearly. Such first sipes 4 exhibit edge effects in different directions. In addition, the first sipe 4 is not limited to such an aspect, and may be, for example, one that extends linearly without having the bent portion 4a, or one that extends in a wavy or zigzag shape.

The second sipe 5 extends linearly, for example. The second sipe 5 may extend in a zigzag or wavy shape. The second sipe 5 is formed with a length smaller than that of the first sipe 4 in this embodiment.

The width W1 of the first sipe 4 and the second sipe 5 is preferably 0.5 to 3.0 mm, for example. The depth D1 (shown in FIG. 3) of the first sipe 4 and the second sipe 5 is preferably 0.5 to 5.0 mm, for example. Also, the shortest distance La between the first sipe 4 and the fifth edge portion 12b is preferably 3 to 8 mm. Furthermore, the shortest distance Lb between the second sipe 5 and the sixth edge 12c is preferably 3-8 mm. In the first block 3 provided with the first sipe 4 and the second sipe 5, the rigidity of the first portion 6 and the second portion 7 is ensured in a well-balanced manner, so the traction performance and the slide control performance are enhanced. be done.

In this specification, unless otherwise specified, the dimensions and the like of each part of the tire are values specified in a normal state.

The "normal state" is a no-load state in which the tire 1 is mounted on a normal rim and filled with a normal internal pressure. In this specification, unless otherwise specified, the dimensions and the like of each part of the tire are values specified in a normal state.

A "regular rim" is a rim defined for each tire in a standard system including the standard on which the tire 1 is based. For ETRTO, it is "Measuring Rim".

"Regular internal pressure" is the air pressure specified for each tire by each standard in the standard system including the standard that Tire 1 is based on. LIMITS AT VARIOUS COLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO.

The first portion 6 is formed in an elongated hexagonal shape in a plan view in the present embodiment. The first portion 6 has, for example, a maximum width portion 6t where the width W2 is maximum at the central portion of the first block 3, and the width W2 gradually decreases toward the second edge portion 11b and the third edge portion 11c. there is The maximum width portion 6t is formed, for example, sandwiched between the bent portions 4a. Such a first portion 6 suppresses a large decrease in rigidity, thereby enhancing the edge effect.

The length (maximum length) L1 of the first portion 6 is preferably 50% or more of the length (maximum length) Lm of the first block 3 . Such a first portion 6 exerts a large edge effect and suppresses excessive reduction in rigidity of the first block 3 .

In the first portion 6, for example, the width L3 of the third edge portion 11c is formed smaller than the length L2 of the second edge portion 11b. As a result, a large deformation of the first portion 6 on the side of the third edge portion 11c is restrained by the second portion 7 on the side of the third edge portion 11c, so that the grip effect of the first portion 6 is suppressed from being lowered.

The first portion 6 is formed such that, for example, the length L4 from the maximum width portion 6t (bent portion 4a) to the second edge portion 11b is smaller than the length L5 from the maximum width portion 6t to the third edge portion 11c. there is As a result, the rigidity of the first portion 6 arranged outside the fourth edge portion 12a becomes relatively small, and the follow-up performance at the time of contact with the ground is maintained at a high level, so excellent traction performance and slide control performance are exhibited. be done.

4 is a plan view of the first block 3. FIG. As shown in FIG. 4, the peripheral portion 10 is formed along a pair of first sipe 4 and second sipe 5 in this embodiment. The peripheral portion 10 includes, for example, a first edge portion 11a to a third edge portion 11c and has a width W3. In this embodiment, the peripheral portion 10 includes a pair of first peripheral portions 10A extending along the first sipe 4, a second peripheral portion 10B extending along the second sipe 5, and a and a third peripheral portion 10C that joins the The first peripheral portion 10A includes a first edge portion 11a. The second peripheral portion 10B includes a second edge portion 11b. The third circumferential portion 10C includes a third edge portion 11c. The peripheral portion 10 is a portion of the first block 3 having the maximum block height in this embodiment. The peripheral portion 10 is formed, for example, with the same width W3. The peripheral portion 10 is not limited to such an aspect.

The central portion 9 is formed surrounded by the peripheral portion 10 in this embodiment. The central portion 9 has, for example, a shape similar to that of the first portion 6 . It should be noted that the central portion 9 is not limited to this.

As shown in FIG. 3, the central portion 9 of this embodiment is formed with a curved surface. Such a central portion 9 deforms to follow the deformation of the peripheral edge portion 10 so as to smoothly contact the ground when it touches the ground. The central portion 9 is formed, for example, by an arc-shaped curved surface that is convex toward the tire radial direction inner side.

The central portion 9 includes, for example, a bottom portion 9a having the smallest block height in the central portion 9 and a wall portion 9b extending from the bottom portion 9a toward the peripheral edge portion 10. As shown in FIG. In this embodiment, the bottom portion 9a is the innermost position in the central portion 9 in the tire radial direction. The bottom portion 9a is formed, for example, in a linear shape having no area between the second peripheral portion 10B and the third peripheral portion 10C. Such a central portion 9 makes the rigidity of the first portion 6 moderately small, and makes smooth contact with the ground.

The angle θ1 between the peripheral portion 10 and the central portion 9 (wall portion 9b) is preferably 10 to 70°. If the angle θ1 is less than 10°, the rigidity of the peripheral portion 10 is small and the peripheral portion 10 deforms excessively, so that the edge effect may not be exhibited. If the angle θ1 exceeds 70°, a decrease in rigidity of the first portion 6 is suppressed, deformation of the peripheral portion 10 is suppressed, and there is a possibility that the central portion 9 will not touch the ground. Therefore, the angle θ1 is more preferably 20° or more, and even more preferably 30° or more. Also, the angle θ1 is desirably 60° or less, and more desirably 50° or less. The angle θ1 is the angle between the normal line n at the position where the peripheral edge portion 10 and the central portion 9 intersect and the extension line 9i extending smoothly from the central portion 9 . When the central portion 9 has a curved surface as in the present embodiment, a tangent line to the central portion 9 at the position where the peripheral portion 10 and the central portion 9 intersect is used as the extension line 9i.

In order to uniformly ground the entire central portion 9, the area Ac of the central portion 9 is preferably 50% or less, more preferably 30% or less, and even more preferably 10% or less of the area A1 of the first portion 6. The area Ac of the central portion 9 is the area of the portion of the central portion 9 with the smallest block height. As described above, the area Ac of the central portion 9 in this embodiment is 0% of the area A1 of the first portion 6 . The area A1 of the first portion 6 is the area of the tread surface 6a of the first portion 6 obtained by filling the central portion 9. As shown in FIG.

The area As of the peripheral portion 10 is desirably 30% or less of the area A1 of the first portion 6 . If the area As of the peripheral edge portion 10 exceeds 30% of the area A1, the rigidity of the peripheral edge portion 10 is large, and the deformation at the time of contact with the ground becomes small, so that the central portion 9 may not be able to contact the ground.

Although not particularly limited, the area A1 of the first portion 6 is desirably 40% to 65% of the area A2 of the second portion . As a result, the rigidity of the first portion 6 is appropriately secured, and the grip effect and edge effect are maintained at a high level.

The block height H1 of the central portion 9 is desirably 80% or more of the block height H3 of the second portion 7 . If the block height H1 of the central portion 9 is less than 80% of the block height H3 of the second portion 7, the bottom portion 9a of the central portion 9 may not touch the ground. The block height H1 of the central portion 9 is the height of the lowest portion of the central portion 9 in the tire radial direction. The block height H3 of the second portion 7 is the portion of the second portion 7 that is positioned furthest outward in the tire radial direction.

From this point of view, the block height H1 of the central portion 9 is more preferably larger than the block height H3 of the second portion 7, and more preferably 110% or more of the block height H3 of the second portion 7. desirable. Further, from the viewpoint of grounding the central portion 9 and the tread surface 7a of the second portion 7 at the same time, the absolute value of the difference between the block height H1 of the central portion 9 and the block height H3 of the second portion 7 |H1−H3 | is more preferably 3.5 mm or less, and even more preferably 2.5 mm or less.

In order to more uniformly ground the central portion 9 and the peripheral portion 10, the block height H1 of the central portion 9 is preferably 90% or more of the block height H2 of the peripheral portion 10. 95% or more of the height H2 is more desirable. When the block height H1 of the central portion 9 exceeds 98% of the block height H2 of the peripheral edge portion 10, the decrease in rigidity of the first portion 6 is suppressed, so that the contact of the central portion 9 may become uneven. be.

The block height H3 of the second portion 7 is preferably about 10 to 20 mm, for example. Although not particularly limited, the difference between the block height H2 of the peripheral portion 10 of the first portion 6 and the block height H3 of the second portion 7 is, for example, approximately 0.3 to 3.0 mm. desirable.

The rubber hardness of the first block 3 is desirably 70 or more. Such a first block 3 digs into the muddy ground and exerts great traction, and also enhances the grip effect on the asphalt road surface, thereby enhancing the traction performance. In this specification, the rubber hardness is the hardness by durometer type A under the environment of 23° C. in accordance with JIS-K6253.

FIG. 5 is a perspective view of the first block 3 of another embodiment. The same reference numerals are given to the same configurations as in the present embodiment, and the description thereof will be omitted. In the first block 3 shown in FIG. 5, the peripheral edge portion 10 is formed only by a pair of first peripheral portions 10A including a first edge portion 11a and a second peripheral portion 10B including a second edge portion 11b, A third circumference is not formed. Such a first portion 6 makes contact with the ground more smoothly than the first portion 6 of the present embodiment, and exhibits a great gripping effect.

6A to 6C are cross-sectional views (the same cross-sectional view as the cross-sectional view taken along line BB in FIG. 1) of the first block 3 of still another embodiment. The same reference numerals are given to the same configurations as in the present embodiment, and the description thereof will be omitted. A first block 3 shown in FIG. 6(a) has a central portion 9 formed of a bottom portion 9a and a wall portion 9b connecting the bottom portion 9a and the peripheral portion 10 in a straight line. The bottom portion 9a of this embodiment has the area Ac of the central portion 9. As shown in FIG.

The first block 3 shown in FIG. 6B is formed such that the peripheral portion 10 does not have the first peripheral portion 10A. The peripheral edge 10 of this embodiment is formed by a pair of first edge 11a, second edge 11b and third edge 11c. Note that the peripheral portion 10 may be formed of, for example, a first peripheral portion 11a, a second peripheral portion 10B, and a third peripheral portion 10C (not shown). The central portion 9 of this embodiment is formed with a curved surface.

The first block 3 shown in FIG. 6(c) has a peripheral edge portion 10 formed without a first peripheral portion 10A, and a central portion 9 formed from a bottom portion 9a and a straight wall portion 9b. It is The peripheral edge 10 of this embodiment is formed by a pair of first edge 11a, second edge 11b and third edge 11c. Note that the peripheral portion 10 may be formed of, for example, a first peripheral portion 11a, a second peripheral portion 10B, and a third peripheral portion 10C (not shown).

7 is a developed view of the tread portion 2. FIG. As shown in FIG. 7, the tread portion 2 of this embodiment is divided into a crown region Cr, a pair of middle regions Md, and a pair of shoulder regions Sh. The crown region Cr is formed including the tire equator C, for example. The shoulder region Sh is formed including the tread edge 2t. Middle region Md is formed between crown region Cr and shoulder region Sh.

Although not particularly limited, for example, the axial width Wc of the crown region Cr is ⅓ of the tread width TW with the tire equator C as the center in the tire axial direction. The width Wd of the middle region Md in the axial direction of the tire and the width Ws of the shoulder region Sh in the axial direction of the tire are each 1/6 of the tread width TW. The tread width TW is the distance in the tire axial direction between the tread ends 2t, 2t when the tread portion 2 is developed on a plane.

The tread portion 2 includes crown blocks 20 arranged in the crown region Cr, middle blocks 21 arranged in the middle region Md, and shoulder blocks 22 arranged in the shoulder region Sh. The first block 3 of this embodiment is formed of a middle block 21 and shoulder blocks 22 . The first block 3 is not limited to such an aspect, and may be formed only in the crown block 20 or only in the middle block 21, for example. Also, the first block 3 may be formed in the crown block 20 , the middle block 21 and the shoulder block 22 . Thus, the first block 3 can be formed into various blocks.

Although the particularly preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the illustrated embodiments and can be modified in various ways.

A motorcycle tire for off-road running having the tread pattern shown in FIG. 7 was manufactured, and the performance of each tire was tested. Common specifications for test methods and tires are as follows. The specifications of the tires for the front wheels were unified, and the tires for the rear wheels with different specifications were evaluated.
Tire size: 80/100-21 (front wheel), 120/80-19 (rear wheel)
Rim size: 1.60 x 21 (front wheel), 2.15 x 19 (rear wheel)
Internal pressure: 80kPa (all wheels)
Second part block height H3: 17mm
Hardness of first block: 70
Angle θ1: 45°
Carcass structure: Bias

<Traction performance, slide control performance>
A test rider drove a test vehicle equipped with the above tire on a test course including a muddy ground, a gravel road, and a dry asphalt road. The test riders sensoryly evaluated the traction performance related to the driving force during running and the slide control performance related to the stability during turning using a 10-point scale. The higher the number, the better the result.
Test vehicle: Motocross competition vehicle with a displacement of 450cc The results of the tests are shown in Table 1.

As a result of the test, it was confirmed that the tire of Example had excellent traction performance and slide control performance.

2 tread portion 3 first block 3c block edge 4 first sipe 5 second sipe 6 first portion 6a tread surface 7 second portion 9 central portion 10 peripheral portion

Claims (6)

A tire including a tread portion,
A first block is formed in the tread portion,
The first block is
a pair of first sipes having ends extending from the block edge and terminating in the tread;
a second sipe connecting between the ends of each of the first sipes;
a first portion surrounded by the pair of first sipes, the second sipes, and the block edge extending between the pair of first sipes; and a second portion surrounding the first portion from three sides,
In the tread surface of the first portion, the central portion is located radially inward of the peripheral portion, and
the peripheral edge portion of the first portion protrudes further outward in the tire radial direction than the second portion;
the block height of the central portion is greater than the block height of the second portion;
tire. A tire including a tread portion,
A first block is formed in the tread portion,
The first block is
a pair of first sipes having ends extending from the block edge and terminating in the tread;
a second sipe connecting between the ends of each of the first sipes;
a first portion surrounded by the pair of first sipes, the second sipes, and the block edge extending between the pair of first sipes; and
including a second portion surrounding the first portion from three sides;
In the tread surface of the first portion, the central portion is located radially inward of the peripheral portion, and
the peripheral edge portion of the first portion protrudes further outward in the tire radial direction than the second portion;
The area of the peripheral portion is 30% or less of the area of the first portion,
tire. A tire including a tread portion,
A first block is formed in the tread portion,
The first block is
a pair of first sipes having ends extending from the block edge and terminating in the tread;
a second sipe connecting between the ends of each of the first sipes;
a first portion surrounded by the pair of first sipes, the second sipes, and the block edge extending between the pair of first sipes; and
including a second portion surrounding the first portion from three sides;
In the tread surface of the first portion, the central portion is located radially inward of the peripheral portion, and
the peripheral edge portion of the first portion protrudes further outward in the tire radial direction than the second portion;
In a cross section perpendicular to the longitudinal direction of the first sipe, the angle between the central portion and the peripheral portion is 10 to 70°,
tire. 4. The tire according to claim 1 or 3 , wherein the area of said central portion is 50% or less of the area of said first portion. The tire according to any one of claims 1 to 4, wherein the central portion is formed with a curved surface. The tire according to any one of claims 1 to 5 , wherein said first block has a rubber hardness of 70 or more .

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