JP6228476B2 - Motorcycle tires for running on rough terrain - Google Patents

Description

  The present invention relates to a motorcycle tire for running on rough terrain that exhibits excellent grip performance on soft roads.

  Patent Document 1 below proposes a motorcycle tire for running on rough terrain having a plurality of blocks in a tread portion. Such a tire causes the block to bite into the road surface and obtains a large frictional force.

  However, even the tire of Patent Document 1 has room for further improvement in grip performance on a relatively soft road surface (hereinafter referred to as a soft road) such as muddy ground, sandy ground, or snowy road.

JP 2012-46078 A

  The present invention has been devised in view of the actual situation as described above, and has improved grip performance on a soft road on the basis of providing an auxiliary block between shoulder blocks spaced in the tire circumferential direction. Its main purpose is to provide motorcycle tires for running on rough terrain.

  The present invention is a motorcycle tire for running on rough terrain having a block pattern in which a plurality of blocks are provided in a tread portion, and the blocks are spaced apart in the tire circumferential direction on the most tread end side. Between the shoulder blocks that include shoulder blocks and are adjacent to each other in the tire circumferential direction, an auxiliary block having a block height smaller than that of the shoulder block is provided, and the auxiliary block passes through the tread end and the shoulder It is characterized by extending across the imaginary surface of the tread extending along the tire circumferential direction along the side surface of the block.

  In the motorcycle tire for traveling on rough terrain according to the present invention, the auxiliary block includes a first portion extending in the tire axial direction and a second portion extending in the tire circumferential direction outside the tire axial direction of the first portion. It is desirable to include.

  In the motorcycle tire for running on rough terrain according to the present invention, the auxiliary block is provided without protruding from the inter-block region where the gap between the shoulder blocks adjacent to each other in the tire circumferential direction is projected in the tire axial direction. Is desirable.

  In the motorcycle tire for running on rough terrain according to the present invention, the inner end of the auxiliary block in the tire axial direction is preferably located on the outer side in the tire axial direction of the inner end of the shoulder block in the tire axial direction. .

  In the motorcycle tire for running on rough terrain according to the present invention, the block includes middle blocks spaced in the tire circumferential direction on the inner side in the tire axial direction of the shoulder block, and the middle blocks are mutually connected in the tire circumferential direction. It is preferable that the gap between adjacent shoulder blocks is provided without protruding from the inter-block region projected in the tire axial direction, and the inner end of the auxiliary block in the tire axial direction is continuous with the middle block.

  In the motorcycle tire for running on rough terrain according to the present invention, the tread portion has a tread pattern in which a tire rotation direction is specified, and the auxiliary block extends from the top surface to the groove bottom surface of the tread portion and the tire. A first side surface disposed on a first arrival side in a rotation direction, and the first side surface has an angle of 60 to 90 ° toward a rear arrival side in the tire rotation direction from the groove bottom surface toward the upper surface side. It is desirable to be tilted.

  The motorcycle tire for running on rough terrain of the present invention has a block pattern in which a plurality of blocks are provided in a tread portion. The block includes shoulder blocks that are spaced apart in the tire circumferential direction on the most tread end side. Between the shoulder blocks adjacent to each other in the tire circumferential direction, an auxiliary block having a smaller block height than the shoulder block is provided. As a result, the number of blocks to be grounded when turning on a soft road increases, and the grip performance is enhanced. Moreover, since the height of the auxiliary block is smaller than that of the shoulder block, contact with the road surface on a relatively hard uneven road surface (hereinafter referred to as a hard road) is prevented, and the shoulder block bites into the road surface. Maintains turning performance on hard roads without obstruction. In addition, such an auxiliary block suppresses mud and the like from being held between the shoulder block and the shoulder block during traveling. For this reason, the outstanding soil removal property is obtained and the fall of the grip performance during driving | running | working is suppressed.

  The auxiliary block extends across the virtual tread end surface extending in the tire circumferential direction along the side surface of the shoulder block through the tread end. Such an auxiliary block pierces the road surface more widely on the outer side in the tire axial direction than the road surface when the vehicle body is brought down to the limit on a soft road. For this reason, the grip force at the time of turning on a soft road is enhanced.

  Accordingly, the motorcycle tire for running on rough terrain of the present invention exhibits excellent grip performance on soft roads while maintaining turning performance on hard roads.

1 is a cross-sectional view showing a motorcycle tire for running on rough terrain according to an embodiment. FIG. 2 is a development view of the tread portion of FIG. 1. It is an expansion perspective view of a tire. (A) is an enlarged plan view of an auxiliary block, (b) is BB sectional drawing of (a). It is an expanded view of the tread part of other embodiment of this invention. It is an expanded view of the tread part of other embodiment of this invention. It is an expanded view of the tread part of other embodiment of this invention. It is an expanded view of the tread part of other embodiment of this invention. It is an expanded view of the tread part of other embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In FIG. 1, a motorcycle tire for motocross competition is illustrated as a motorcycle tire (hereinafter simply referred to as “tire”) 1 for traveling on rough terrain of the present embodiment. FIG. 1 is a cross-sectional view of the tire 1 in a normal state.

  The “normal state” is an unloaded state in which a tire is assembled on a normal rim (not shown) and filled with a normal internal pressure. Hereinafter, unless otherwise specified, the dimensions and the like of each part of the tire are values measured in this normal state.

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

  The “regular internal pressure” is an air pressure determined by each standard for each tire in the standard system including the standard on which the tire is based. “JATMA” indicates “maximum air pressure”, and TRA indicates “TIRE LOAD LIMITS”. The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” in the case of ETRTO.

  As shown in FIG. 1, the tire 1 of the present embodiment includes a carcass 6 and a tread reinforcing layer 7.

  The carcass 6 reaches the bead core 5 of the bead part 4 from the tread part 2 through the sidewall part 3. The carcass 6 is constituted by, for example, one carcass ply 6A. The carcass ply 6A includes a main body portion 6a and a folded portion 6b. The main body portion 6 a extends from the tread portion 2 through the sidewall portion 3 to the bead core 5 embedded in the bead portion 4. The folded portion 6 b is continuous with the main body portion 6 a and is folded around the bead core 5.

  The carcass ply 6A has, for example, a carcass cord arranged with an inclination with respect to the tire equator C. The carcass ply 6A of the present embodiment has a radial structure in which carcass cords are arranged at an angle of 65 to 90 ° with respect to the tire equator C. For the carcass cord, for example, an organic fiber cord such as nylon, polyester, or rayon is suitably employed.

  A bead apex rubber 8 is provided between the main body portion 6a and the folded portion 6b. The bead apex rubber 8 extends from the bead core 5 outward in the tire radial direction. The bead apex rubber 8 is formed of, for example, hard rubber. Thereby, the bead part 4 is effectively reinforced.

  The tread reinforcing layer 7 is disposed, for example, on the outer side in the tire radial direction of the carcass 6 and on the inner side of the tread portion 2. The tread reinforcing layer 7 is composed of, for example, one reinforcing ply 7A. In the reinforcing ply 7A, for example, reinforcing cords are arranged to be inclined with respect to the tire equator C. For example, an organic fiber cord such as aramid or rayon is suitably used as the reinforcing cord.

  The outer surface of the tread portion 2 is convex and curved outward in the tire radial direction. A tread width TW which is a distance in the tire axial direction between the tread ends Te and Te of the tread portion 2 forms the maximum tire width.

  The tread end Te means the edge 10e on the outer side in the tire axial direction of the block 10 that is located on the outermost side in the tire axial direction among the blocks 10 that are in contact with the ground when traveling on a paved road (including when the vehicle body is pushed down to the limit).

  FIG. 2 is a development view of the tread portion 2 of the tire 1 of FIG. 1, and an AA sectional view thereof is shown in FIG. 1. As shown in FIG. 2, the tread portion 2 has a tread pattern in which the tire rotation direction R is designated. The tire rotation direction R is displayed by, for example, characters or marks on a sidewall portion or the like.

  The tread portion 2 is provided with a plurality of blocks 10. Each block 10 protrudes from the groove bottom surface 9 that forms the outer surface of the tread portion 2. The block 10 of the present embodiment includes, for example, a center block 11, a shoulder block 12, and a middle block 13. The center block 11 is provided on the tire equator C, for example. The shoulder block 12 is provided on the most tread end Te side. The middle block 13 is provided between the center block 11 and the shoulder block 12. The center block 11, the shoulder block 12, and the middle block 13 are spaced apart from each other in the tire circumferential direction.

  An auxiliary block 20 is provided between the shoulder blocks 12 adjacent to each other in the tire circumferential direction.

  FIG. 3 is an enlarged perspective view of the auxiliary block 20. As shown in FIG. 3, the auxiliary block 20 has a smaller block height than the shoulder block 12.

  Since such an auxiliary block 20 prevents contact with the road surface on a hard road, the turning performance on the hard road is maintained without inhibiting the biting of the shoulder block into the road surface when turning. On the other hand, on soft roads, tires are buried in the road surface to the vicinity of the sidewalls even when turning with a relatively small camber angle. For this reason, on a soft road, the auxiliary block 20 effectively shears mud and the like, and exhibits a large frictional force in a wider range. Moreover, such an auxiliary block 20 prevents mud and the like from being held between the shoulder block and the shoulder block during traveling. For this reason, the outstanding soil removal property is obtained and the fall of the grip performance during driving | running | working is suppressed.

  As shown in FIG. 2, the auxiliary block 20 extends across the tread end virtual surface 15. That is, the auxiliary block 20 extends from the tread end virtual surface 15 to the inside and the outside in the tire axial direction. The tread end virtual surface 15 is a virtual surface extending in the tire circumferential direction along the side surface 12s of the shoulder block 12 through the tread end Te. Such an auxiliary block 20 pierces the road surface more widely on the outer side in the tire axial direction than the road surface when the vehicle body is pushed down to the limit on a soft road. For this reason, the grip force at the time of turning on a soft road is enhanced.

  In order to further exhibit the above-described effects, it is desirable that the auxiliary block 20 is provided without protruding in the tire circumferential direction from the inter-block region 16 of the shoulder block 12, for example. The inter-block region 16 is a region in which the gap between the shoulder blocks 12 adjacent to each other in the tire circumferential direction is projected in the tire axial direction. As a result, the shoulder block 12 and the auxiliary block 20 cooperate to exert a large frictional force in the tire axial direction.

  As shown in FIG. 1, it is desirable that the auxiliary block 20 be provided on the outer side in the tire radial direction with respect to the outer end 6e of the folded portion 6b. Thereby, the increase in the vertical spring of a tire is suppressed and the outstanding shock absorption performance is obtained.

  As illustrated in FIG. 2, the auxiliary block 20 includes, for example, a first portion 21 and a second portion 22.

  For example, the first portion 21 extends in the tire axial direction. For example, the second portion 22 extends in the tire circumferential direction outside the first portion 21 in the tire axial direction. The first portion 21 and the second portion 22 of the present embodiment are connected in a substantially T shape. Such an auxiliary block 20 exhibits a friction force with a good balance with respect to the tire axial direction and the tire circumferential direction.

  For example, the first portion 21 extends linearly along the tire axial direction. For example, the first portion 21 crosses the tread end virtual surface 15.

  The inner end 21i in the tire axial direction of the first portion 21 is preferably located, for example, on the outer side in the tire axial direction from the inner end 12i in the tire axial direction of the shoulder block 12. Thereby, the reaction force when the block shears mud or the like in the tire circumferential direction is not concentrated on the inner end 21i but is distributed to the shoulder block 12. Therefore, damage to the auxiliary block 20 starting from the inner end 21i is effectively suppressed.

  FIG. 4A shows an enlarged plan view of the auxiliary block 20. As shown in FIG. 4, the width W1 of the first portion 21 is preferably 5 mm or more, more preferably 7 mm or more, preferably 10 mm or less, more preferably 8 mm or less. Such a first portion 21 enhances grip performance while maintaining soil removal. The first portion 21 of the present embodiment has a substantially constant width.

  The length L1 of the first portion 21 in the tire axial direction is preferably 20 mm or more, more preferably 30 mm or more, preferably 50 mm or less, more preferably 40 mm or less. Such a first portion 21 exhibits excellent traction performance while suppressing damage to the block.

  The second portion 22 is provided, for example, on the outer side in the tire axial direction than the tread end virtual surface 15 (shown in FIG. 2). For example, the second portion 22 extends linearly along the tire circumferential direction. In the present embodiment, the width W <b> 2 of the second portion 22 is determined within the same range as the width W <b> 1 of the first portion 21. For example, the second portion 22 has a substantially constant width.

  The length L2 in the tire circumferential direction of the second portion 22 is desirably smaller than the width W3 of the shoulder block 12 in the tire axial direction. The length L2 of the second portion 22 in the tire circumferential direction is preferably 0.65 times or more, more preferably 0.70 times or more, the width W3 (shown in FIG. 2) of the shoulder block 12 in the tire axial direction. Is 0.80 times or less, more preferably 0.85 times or less. Such a second portion 22 enhances the grip performance during turning while maintaining the soil removal property.

  FIG. 4B shows a cross-sectional view of the auxiliary block 20 in FIG. As shown in FIG. 4 (b), the height h1 of the auxiliary block 20 is preferably 0.2 times or more, more preferably 0.3 times or more the height h2 (shown in FIG. 1) of the shoulder block 12. It is preferably 0.5 times or less, more preferably 0.4 times or less. Thereby, the outstanding grip performance is exhibited, suppressing the damage of the auxiliary block 20.

  The height h1 of the auxiliary block 20 is desirably at least 3 mm. Such an auxiliary block 20 effectively shears mud and the like on the road surface and improves grip performance.

  The auxiliary block 20 has a first side surface 25 extending from the upper surface 24 to the groove bottom surface 9 of the tread portion.

  For example, the side surface 25 is preferably inclined toward the rear arrival side of the tire rotation direction R from the groove bottom surface 9 toward the upper surface 24 side. Thereby, damage to auxiliary block 20 is controlled.

  The angle θ1 of the first side surface 25 with respect to the virtual bottom surface 20d of the auxiliary block 20 along the groove bottom surface 9 is preferably 60 ° or more, more preferably 70 ° or more, preferably 90 ° or less, more preferably Is 80 ° or less. Such an auxiliary block 20 improves traction performance while suppressing damage to the block.

  5 to 9 are developed views of the tread portion 2 according to another embodiment of the present invention. Reference numerals shown in FIGS. 5 to 9 indicate the respective configurations described above.

  In the embodiment of FIG. 5, the middle block 13 is provided without protruding into the inter-block region 16 of the shoulder block 12. Moreover, the inner end 20 i of the auxiliary block 20 in the tire axial direction is connected to the middle block 13. Thereby, damage to the block starting from the inner end 20i of the auxiliary block 20 is suppressed. Moreover, such an auxiliary block 20 shears mud and the like in a wide range in the tire axial direction and exhibits excellent traction performance.

  The auxiliary block 20 of the embodiment of FIG. 6 has a first portion 21 extending in the tire axial direction and a second portion 22 connected to the first portion 21 in a substantially L shape. The second portion 22 extends from the outer end portion 21 o of the first portion 21 in the tire axial direction toward the first arrival side in the tire rotation direction R. Such an auxiliary block 20 captures mud and the like at the corner 27 between the first portion 21 and the second portion 22 and exhibits excellent traction performance.

  In the auxiliary block 20 of the embodiment of FIG. 7, the second portion 22 connected to the outer side in the tire axial direction of the first portion 21 is inclined inward in the tire axial direction toward the first arrival side in the tire rotation direction R. In such an auxiliary block 20, the corner portion 27 between the first portion 21 and the second portion 22 presses mud and the like and a large shearing force is obtained. For this reason, the grip performance at the time of turning on a soft road is improved.

  The auxiliary block 20 of the embodiment of FIG. 8 is, for example, a first portion 21 that extends linearly in the tire axial direction, and a gentle curve toward the first arrival side in the tire rotation direction R outside the first portion 21 in the tire axial direction. And a second portion 22 to be included. Thereby, the outstanding traction performance is obtained, maintaining the durability of the auxiliary block 20.

  The auxiliary block 20 of the embodiment of FIG. 9 is curved in an arc shape, for example. The auxiliary block 20 extends from the inner end 20i in the tire axial direction toward the first arrival side in the tire rotation direction R toward the outer side in the tire axial direction. In addition, the angle θ2 of the auxiliary block 20 with respect to the tire axial direction gradually increases toward the outer side in the tire axial direction. Such an auxiliary block 20 compresses mud and the like while guiding it inward in the tire axial direction during traveling. For this reason, the traction performance and the grip performance at the time of turning can be improved in a balanced manner.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

A motorcycle tire for traveling on rough terrain having the tread pattern of FIG. 1 was prototyped based on the specifications shown in Table 1. As Comparative Example 1, a tire without an auxiliary block was manufactured as a prototype. These test tires were mounted on the rear wheels of the test vehicle and tested for performance. The common specifications and test methods for each test tire are as follows.
Vehicle used: Displacement 450cc Motorcycle Tire size: 120 / 80-19
Rim size: 2.15 × 19
Internal pressure: 80 kPa

<Grip performance, traction performance, shock absorption performance when turning>
Under the above conditions, the “grip performance during turning”, “traction performance”, and “shock absorption performance” when running on a rough course including soft roads were evaluated based on the driver's sensuality. A result is a score which sets the value of the comparative example 1 to 100, and shows that it is so favorable that a numerical value is large.
The test results are shown in Table 1.

  As a result of the test, it was confirmed that the tires of the examples exhibited excellent grip performance on soft roads.

2 Tread part 10 blocks 12 Shoulder block 15 Tread end virtual surface 20 Auxiliary block

Claims (6)

A motorcycle tire for running on uneven terrain having a block pattern in which a plurality of blocks are provided in a tread portion,
The block includes a shoulder block spaced in the tire circumferential direction on the most tread end side,
Between the shoulder blocks adjacent to each other in the tire circumferential direction, an auxiliary block having a smaller block height than the shoulder block is provided,
A motorcycle tire for running on rough terrain, wherein the auxiliary block extends across a virtual tread end surface extending in the tire circumferential direction along the side surface of the shoulder block through the tread end.   2. The automatic for rough terrain travel according to claim 1, wherein the auxiliary block includes a first portion extending in a tire axial direction and a second portion extending in the tire circumferential direction outside the first portion in the tire axial direction. Tires for motorcycles.   The motorcycle for traveling on rough terrain according to claim 1 or 2, wherein the auxiliary block is provided without protruding from a region between the blocks in which a gap between the shoulder blocks adjacent to each other in the tire circumferential direction is projected in the tire axial direction. Tires.   4. The automatic for rough terrain travel according to claim 1, wherein an inner end in the tire axial direction of the auxiliary block is located on an outer side in the tire axial direction with respect to an inner end in the tire axial direction of the shoulder block. Tires for motorcycles. The block includes a middle block spaced in the tire circumferential direction on the inner side in the tire axial direction of the shoulder block,
The middle block is provided without protruding from the area between the blocks projected in the tire axial direction of the gap between the shoulder blocks adjacent to each other in the tire circumferential direction,
The tire for motorcycles for rough terrain travel according to any one of claims 1 to 3 , wherein an inner end of the auxiliary block in the tire axial direction is continuous with the middle block. The tread portion has a tread pattern in which a tire rotation direction is designated,
The auxiliary block extends from the top surface to the groove bottom surface of the tread portion and has a side surface on the first arrival side arranged on the first arrival side in the tire rotation direction,
The rough terrain according to any one of claims 1 to 5, wherein the side surface on the first arrival side is inclined at an angle of 60 to 90 ° toward the rear arrival side in the tire rotation direction from the groove bottom surface toward the upper surface side. Motorcycle tires for running.

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