JP7283201B2 - tire - Google Patents

Description

The present invention relates to tires.

Patent Literature 1 listed below describes a pneumatic tire for running on all terrain in which a plurality of blocks are provided in a tread portion. The blocks include high blocks having the greatest height and low blocks having a smaller height than the high blocks.

Japanese Patent Application Laid-Open No. 2007-131111

The pneumatic tire of Patent Document 1 has room for improvement, for example, 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 invention according to claim 1 of the present invention is a tire including a tread portion, wherein the tread portion is formed with first blocks, and the first blocks divide the tread and intersect each other. a pair of sipes that extend without a line, a first portion formed between the pair of sipes, and a pair of second portions formed on both outer sides of the pair of sipes, the block height of the first portions The height is a tire that is different from the block height of said pair of second portions.

In the tire according to the present invention, it is desirable that the block height of the first portion is greater than the block height of the pair of second portions.

In the tire according to the present invention, it is preferable that the tread surface of the first portion protrudes from the pair of second portions in a plan view of the first block.

In the tire according to the present invention, it is preferable that the tread surface of the first portion protrudes from only one of the pair of second portions.

In the tire according to the present invention, it is preferable that the tread surface of the first portion protrudes from both sides of the pair of second portions.

In the tire according to the present invention, it is preferable that the maximum length of the tread surface of the first portion is 1.5 times or less the length of the sipe along the direction of the maximum length.

In the tire according to the present invention, it is desirable that the shortest distance between the pair of sipes is 2 mm or more.

In the tire according to the present invention, it is desirable that the sipe extends along the tire circumferential direction.

In the tire according to the present invention, it is desirable that the sipe extends along the tire axial direction.

In the tire according to the present invention, it is desirable that the sipe extends linearly.

In the tire according to the present invention, it is desirable that the sipe includes a bent portion.

A first block is formed in the tire of the present invention. The first block includes a pair of sipes that divide the tread and extend without intersecting each other, a first portion formed between the pair of sipes, and a pair of sipes formed on both outer sides of the pair of sipes. and a second portion. The block height of the first portion is different than the block height of the pair of second portions.

Thus, since the first portion and the second portion are formed of the sipe that divides the tread, they can effectively deform to each other when the first block touches the ground. Further, at the time of ground contact, the first portion or the second portion, whichever has the greater block height, deforms inward in the tire radial direction, and both the first portion and the second portion contact the ground. Become. Furthermore, the sipe suppresses excessive decrease in rigidity of the first block. Therefore, the first portion and the second portion have a high edge effect, and increase the frictional force with respect to the road surface in the tire circumferential direction and the tire axial direction. 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. (a) is a plan view of a first block, and (b) is a cross-sectional view taken along the line AA of (a). 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 plan views of the first block of still another embodiment. FIG. 3 is a development view of the tread portion of the embodiment; FIG. 4 is an exploded view of a tread portion of another 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. 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 FIG. 1, 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, and a block wall 3b that connects the tread surface 3a and the block wall 3b. and block edges 3c formed as boundaries and edges.

FIG. 2(a) is a plan view of the first block 3, and FIG. 2(b) is a sectional view taken along the line AA of (a). The vertical direction in FIG. 2(a) is the tire circumferential direction, and the horizontal direction in FIG. 2(a) is the tire axial direction. As shown in FIGS. 1 and 2, the tread surface 3a of the first block 3 is formed in a rectangular shape in this embodiment. The tread surface 3a of the first block 3 can adopt various shapes such as a hexagonal shape, a trapezoidal shape, and a circular shape.

The first block 3 of this embodiment includes a pair of sipes 4, 4 that divide the tread surface 3a and extend without intersecting each other, a first portion 5 formed between the pair of sipes 4, 4, and a pair of and a pair of second portions 6,6 formed on opposite sides of the sipes 4,4. Thus, since the first portion 5 and the second portion 6 are formed of the sipe 4 that divides the tread surface 3a, they can be effectively deformed to each other when the first block 3 touches the ground. Moreover, the sipe 4 suppresses an excessive decrease in rigidity of the first block 3 .

The block height H1 of the first portion 5 differs from the block height H2 of the second portion 6 . Therefore, at the time of ground contact, the larger block height of the first portion 5 or the second portion 6 deforms inward in the tire radial direction, and both the first portion 5 and the second portion 6 touch the ground. Become. Therefore, since the first portion 5 and the second portion 6 have a high edge effect and increase the frictional force against the road surface, the tire 1 of the present embodiment has improved traction performance and slide control performance.

The block height H1 of the first portion 5 is greater than the block height H2 of the second portion 6 in this embodiment. A large contact pressure is likely to act on the first portion 5 arranged on the central side of the first block 3 when it comes into contact with the road surface. Therefore, the first portion 5 is easily deformed inward in the tire radial direction, and the first portion 5 and the second portion 6 can more uniformly contact the ground. Therefore, the tire 1 of this embodiment has excellent traction performance and slide control performance.

The sipe 4 extends linearly in this embodiment. Such a sipe 4 suppresses an excessive decrease in rigidity of the first block 3 .

The sipe 4 extends, for example, along the tire circumferential direction. As a result, the frictional force acting in the axial direction of the tire is increased, so particularly the slide control performance is improved. The above-mentioned "along the tire circumferential direction" includes not only a mode parallel to the tire circumferential direction but also a mode in which the angle θ1 with respect to the tire circumferential direction is 10 degrees or less.

The sipe 4 may extend, for example, along the tire axial direction (not shown). Such a sipe 4 enhances the frictional force acting in the tire circumferential direction, and thus particularly improves the traction performance. In order to effectively exhibit such action, the sipe 4 may be formed at an angle θ1 of 80 degrees or more with respect to the tire circumferential direction.

The pair of sipes 4 includes a first sipe 8 (left side in the drawing) and a second sipe 9 (right side in the drawing) extending along the first sipe 8 . Since such a sipe 4 reduces the difference in rigidity in the longitudinal direction of the first portion 5, the edge effect of the first portion 5 is highly exhibited. The above-mentioned "along the first sipe 8" means that the second sipe 9 and the first sipe 8 are parallel to each other, and the difference in the angle θ1 between the second sipe 9 and the first sipe 8 is 10 degrees or less. It is intended to include certain aspects. In this embodiment, the first sipe 8 extends parallel to the second sipe 9 .

The shortest distance L1 between the pair of sipes 4, 4 is desirably 2 mm or more. Thereby, a high rigidity of the first portion 5 is ensured. If the shortest distance L1 is excessively large, the rigidity of the second portion 6 is reduced. Therefore, the shortest distance L1 is desirably 0.6 times or more the width W1 of the sipe 4, and more desirably 1 time or more. The shortest distance L1 is desirably 40 times or less the width W1 of the sipe 4, and more desirably 15 times or less.

In this specification, unless otherwise specified, the dimensions and the like of each portion of the tire 1 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.

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 width W1 of the sipe 4 is desirably, for example, 0.5 mm or more, and more desirably 1.0 mm or more. Also, the width W1 of the sipe 4 is desirably 2.0 mm or less, more desirably 1.5 mm or less. For example, the depth D1 of the sipe 4 is desirably 0.3 mm or more, and more desirably 1.0 mm or more. The depth D1 of the sipe 4 is desirably 30 mm or less, more desirably 15 mm or less. In this embodiment, the width W1 and the depth D1 of the first sipe 8 and the second sipe 9 are the same.

The tread surface 5a of the first portion 5 is formed in a rectangular shape in this embodiment. The tread surface 6a of each second portion 6 is formed in a rectangular shape in this embodiment. The shape of the tread surface 5a of the first portion 5 and the tread surface 6a of the second portion 6 is not limited to such an aspect.

The block edge 5c of the first portion 5 includes, for example, a pair of first edges 11a, 11a formed along each sipe 4, and a second edge 11b connecting both ends of each first edge 11a (in the figure, upper side) and a third edge 11c (lower side in the figure). In this embodiment, the block edge 6c of each second portion 6 includes a fifth edge 12a formed by the sipe 4, a sixth edge 12b extending from both ends of the fifth edge 12a (upper side in the figure), and a third edge 12b. 7 edge portions 12c and an eighth edge portion 12d joining the sixth edge portion 12b and the seventh edge portion 12c. Each edge 11a-11c and 12a-12d in this embodiment extends linearly.

A tread surface 5 a of the first portion 5 protrudes from the second portion 6 . Such a first portion 5 increases the frictional force with the road surface, thereby improving traction performance and slide control performance.

The tread surface 5 a of the first portion 5 protrudes from both sides of the second portion 6 . As a result, the above effects are exhibited more effectively. In the present embodiment, the second edge 11b is located outside (upper in the figure) of the first block 3 than the sixth edges 12b of both second portions 6. As shown in FIG. In addition, the third edge 11c is located outside the first block 3 (lower in the drawing) than the seventh edges 12c of the two second portions 6. As shown in FIG.

The tread surface 5a of the first portion 5 may protrude from only one side of the second portion 6 (not shown). Even in such a mode, a large frictional force is exerted by the first portion 5 to improve slide control performance and traction performance.

The difference (H1-H2) between the block height H1 of the first portion 5 and the block height H2 of the second portion 6 is preferably 0.4% or more of the block height H2 of the second portion 6, for example. % or more is more desirable. Also, the difference (H1-H2) is preferably 70% or less, more preferably 20% or less, of the block height H2 of the second portion 6, for example. As a result, the rigidity of the first block 3 is ensured, and the rigidity of the first portion 5 or the second portion 6 is moderately reduced, so that the contact pressure between the first portion 5 and the second portion 6 is uniform. can be As a result, a higher edge effect is exhibited, and slide control performance and traction performance are effectively enhanced.

FIG. 3 is a plan view of the first block 3. FIG. As shown in FIG. 3, the maximum length L3 of the tread surface 5a of the first portion 5 is preferably 1.5 times or less the length L4 of the sipe 4 along the direction of the maximum length L3. When the maximum length L3 exceeds 1.5 times the length L4, the rigidity of the projecting portion of the first portion 5, which in this embodiment includes the second edge portion 11b and the third edge portion 11c, is reduced, Since cracks and chipping occur, there is a risk that the frictional force cannot be increased sufficiently. From this point of view, the maximum length L3 is preferably 1.1 to 1.4 times the length L4. The maximum length L3 of the tread 5a of the first portion 5 is the distance between the midpoints of the farthest block edges 5c of the first portion 5. As shown in FIG. In this embodiment, the maximum length L3 is the length of the imaginary straight line 13 passing through the midpoint 11f of the second edge portion 11b and the midpoint 11h of the third edge portion 11c. The maximum length direction is the direction in which the virtual straight line 13 extends.

From a similar point of view, the protruding length L5 of the first portion 5 is preferably 30% or less, more preferably 20% or less, and even more preferably 15% or less of the length L4 of the sipe 4 . The projecting length L5 of the first portion 5 is desirably 5% or more of the length L4 of the sipe 4 . The protruding length L5 is the distance between the imaginary block edge 14 smoothly connecting the block edges 6c, 6c of the pair of second portions 6 and the protruding end 5e of the first portion 5, which is the third edge 11c in this embodiment. is the shortest length between

The ratio (A1/A2) between the area A1 of the tread surface 5a of the first portion 5 and the total area A2 of the tread surfaces 6a of both second portions 6 is preferably 20% or more, more preferably 40% or more. The ratio (A1/A2) is desirably 80% or less, more desirably 60% or less. As a result, the traction performance and the slide control performance can be improved in a well-balanced manner.

FIG. 4 is a perspective view of the first block 3 of another embodiment. The same configuration modes as those of the first block 3 of the present embodiment are denoted by the same reference numerals, and descriptions thereof are omitted. The first block 3 of this embodiment has a block height H1 of the first portion 5 smaller than a block height H2 of the second portion 6 . In such a mode, when the first block 3 is grounded, the pair of second portions 6 are grounded first. Effective. Even in such a mode, the second portion 6 deforms inward in the tire radial direction, and the first portion 5 and the second portion 6 come into contact with the ground. In this aspect, the difference (H2-H1) between the block height H2 of the second portion 6 and the block height H1 of the first portion 5 is 0.4% or more of the block height H1 of the first portion 5. is desirable, and 5% or more is more desirable. The difference (H2-H1) is desirably 70% or less of the block height H1 of the first portion 5, and more desirably 20% or more.

FIGS. 5(a) to 5(c) are plan views 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. As shown in FIG. 5( a ), the first block 3 is formed such that each sipe 4 extends linearly while being inclined with respect to the tire circumferential direction. In such a first block 3, the block edge 3c has an edge component in the tire circumferential direction and an edge component in the tire axial direction. Further, in this embodiment, the maximum length L3 of the tread surface 5a of the first portion 5 is formed longer than the maximum length L3 of the first portion 5 of this embodiment, thereby exhibiting a high edge effect.

As shown in FIG. 5(b), each sipe 4 of the first block 3 is formed including a bent portion 15. As shown in FIG. The sipe 4 is formed, for example, in a horizontal V shape including a first bent portion 15A that bends to one side (right side in the drawing) with respect to the tire axial direction. The block edge 3c of such a first block 3 also has an edge component in the tire axial direction and an edge component in the tire circumferential direction. Although not particularly limited, the inclination angle θ2 of the first bent portion 15A is desirably formed at about 60 to 120 degrees.

As shown in FIG. 5( c ), each sipe 4 of the first block 3 is also formed including a bent portion 15 . The sipe 4 includes, for example, a first bent portion 15A and a second bent portion 15B bent in the opposite direction to the first bent portion 15A. The sipe 4 of this embodiment is formed in a wavy shape with a curved portion 15 forming a smooth arc. In such a first block 3, the block edge 3c has edge components in multiple directions.

FIG. 6 is a developed view of the tread portion 2 on which the first blocks 3 as described above are arranged. As shown in FIG. 6, 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 only in the middle block 21 . 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 shoulder block 22, for example. Also, the first block 3 may be formed in blocks of any two regions, or may be formed in blocks of all regions.

FIG. 7 is an exploded view of the tread portion 2 of another embodiment. The same reference numerals are given to the same configurations as in the embodiment of FIG. 6, and the description thereof will be omitted. In the tread portion 2 of this embodiment, the first block 3 is formed on the middle block 21 . The first block 3 has, for example, a sipe 4 extending linearly. In the tread portion 2, for example, a first block group 18 including a plurality of first blocks 3 arranged in the tire circumferential direction is formed. In the first block group 18, the angle θ1 (shown in FIG. 2(a)) of the sipe 4 is larger or smaller toward the first block 3 on one side in the tire circumferential direction. In the present embodiment, in the first block group 18, the angle θ1 of the sipe 4 increases (the sipe 4 rotates clockwise) toward the first block 3 on one side (lower side in the figure) in the tire circumferential direction. there is Such a first block group 18 has edge components in multiple directions. In addition, the sipes 4 arranged in the first blocks 3 of the tread portion 2 of this embodiment are not limited to those extending linearly. Sipe 4 may be employed. Further, in the first block group 18, the angle θ1 of the sipe 4 may be smaller (the sipe 4 is rotated counterclockwise) toward the first block 3 on one side in the tire circumferential direction.

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. 6 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)
Area ratio A1/A2: 55%
H1: 10mm
W1: 1.2mm
D1: 1.5mm

<Slide control performance, traction performance and grip 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. Test riders sensory evaluated slide control performance, traction performance and grip performance on a 10-point scale. Slide control performance is an evaluation of the ease of vehicle control and vehicle stability during cornering. Traction performance is an evaluation of smooth acceleration during running. Grip performance is an evaluation of smooth braking performance during straight running and stable braking performance during cornering. 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. In addition, the tires of Examples are excellent in grip performance.

1 tire 2 tread portion 3 first block 4 sipe 5 first portion 6 second portion H1 block height of first portion H2 block height of second portion

Claims (10)

A tire including a tread portion,
A first block is formed in the tread portion,
The first block includes a pair of sipes that divide the tread and extend without intersecting each other, a first portion formed between the pair of sipes, and a pair of sipes formed on both outer sides of the pair of sipes. a second portion;
The block height of the first portion is different from the block height of the pair of second portions,
In a plan view of the first block,
The tread surface of the first portion protrudes from the pair of second portions,
tire. 2. The tire of claim 1, wherein the block height of said first portion is greater than the block height of said pair of second portions. The tire according to claim 1 or 2 , wherein the tread surface of the first portion protrudes from only one of the pair of second portions . The tire according to claim 1 or 2 , wherein the tread surface of the first portion protrudes from both sides of the pair of second portions . 5. Tire according to any one of claims 1 to 4 , wherein the maximum length of the tread of said first portion is no more than 1.5 times the length of said sipe along said maximum length direction. The tire according to any one of claims 1 to 5 , wherein the shortest distance between said pair of sipes is 2 mm or more . The tire according to any one of claims 1 to 6 , wherein the sipe extends along the tire circumferential direction . The tire according to any one of claims 1 to 6 , wherein said sipe extends along the tire axial direction . The tire according to any one of claims 1 to 8 , wherein said sipe extends linearly . 9. A tire according to any one of the preceding claims, wherein the sipe includes bends .

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