JP2010173459A - Tire for motorcycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress emergence of a cord in a groove bottom positioned in a block train on the outermost side of a tire in the width direction without changing existing block pattern design in a tread. <P>SOLUTION: The tire is provided with: a belt layer 18 having at least one layer, positioned on the outside of a carcass ply in the tire diametrical direction; and a tread 26 positioned on the outside of the belt layer 18 in the tire diametrical direction and having a pattern comprised of a plurality of block trains. An end 18A of the belt layer 18 in the tire width direction is terminated between an end 20A of the block train 20 on the tire equatorial plane CL side and a center 20C of the block train 20 in the width direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a motorcycle tire, and more particularly to a motorcycle tire for motocross and enduro for use on rough terrain including muddy ground.

  A pneumatic tire for motorcycles for traveling on rough terrain is disclosed (see Patent Document 1).

JP 2008-105581 A

  Conventionally, it has been usual to terminate the end portion in the tire width direction of the reinforcing layer (belt layer) provided in the lower layer of the tread at a position where it intersects the perpendicular line extending from the tread end. However, if the tread on the outer side in the tire radial direction of the belt layer has a pattern consisting of a plurality of blocks, the amount of rubber sucked up in the vulcanization process is constant depending on the distance to the adjacent blocks and the number of blocks. In other words, in a block row having a large total volume, the amount of tread rubber sucked up during vulcanization increases, and cords are likely to be generated at the bottom of the groove in the block row.

  Here, the term “cord out” means that the rubber cage from the groove bottom around the tread block to the belt layer becomes thin, and the uneven shape of the cord in the belt layer appears at the groove bottom. When this cord is generated, it is considered that cracks are likely to occur at the groove bottom, and as a result, tire failure is likely to occur.

  In particular, if the end of the belt layer in the tire width direction is set to end beyond the center in the width direction of the outermost block row in the tire width direction, cording occurs at the groove bottom of the block row, and the end of the tread Cracks are likely to occur from the part. In order to prevent the cord from coming out in the vicinity of the outermost block row in the tire width direction, it is conceivable to increase the rubber gauge to increase the amount of rubber remaining on the groove bottom after vulcanization, but this will increase the tire mass. End up.

  In some cases, it was necessary to change the block pattern design in order to prevent code generation.

  In consideration of the above-described facts, the present invention has an object to suppress the occurrence of cording at the groove bottom located in the outermost block row in the tire width direction without changing the current block pattern design in the tread. .

  According to the first aspect of the present invention, at least one layer of carcass ply wound around a bead core disposed between the pair of bead portions in a toroidal shape from the inside to the outside and positioned on the outer side in the tire radial direction of the carcass ply A tire for a motorcycle having at least one belt layer and a tread having a pattern composed of a plurality of block rows located outside the belt layer in the tire radial direction. The end portion terminates between the end portion on the tire equatorial plane side of the block row located on the outermost side in the tire width direction and the center in the width direction of the block row.

  The motorcycle tire according to claim 1, wherein at least one layer of the carcass ply is wound around the bead core disposed between the pair of bead portions in a toroidal shape and wound around from the inside to the outside, and the tire of the carcass ply. An end portion of the belt layer in the tire width direction, the belt layer having at least one belt layer located on the radially outer side and a tread having a pattern composed of a plurality of block rows located on the outer side in the tire radial direction of the belt layer; Is terminated between the end of the block row located on the outermost side in the tire width direction on the tire equatorial plane side and the center in the width direction of the block row, without changing the current block pattern design in the tread. In addition, it is possible to suppress the occurrence of cording at the groove bottom located in the outermost block row in the tire width direction.

  According to a second aspect of the present invention, in the motorcycle tire according to the first aspect, the block row positioned at the outer portion in the tire width direction is more blocked than the block row positioned at the center portion in the tire width direction of the tread. And the total volume of the block is large.

  In the motorcycle tire according to claim 2, the number of blocks in the block row located on the outer side in the tire width direction is larger than that in the block row located in the center portion in the tire width direction of the tread. Since the total volume is large, it is possible to improve the steering stability while suppressing the occurrence of cording at the groove bottom located in the outermost block row in the tire width direction.

  As described above, according to the motorcycle tire of the present invention, it is possible to suppress the occurrence of the belt layer cording at the groove bottom around the block without changing the current block pattern design in the tread. Excellent effect is obtained.

1 is a cross-sectional view showing a motorcycle tire. It is a top view which shows the tread pattern of the tire for motorcycles.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, a motorcycle tire 10 according to the present embodiment is a motorcycle tire for motocross and enduro intended for use on rough terrain including muddy ground, and includes a carcass ply 16 and a belt layer 18. And a tread 26.

  The carcass ply 16 is configured by straddling between a pair of bead portions 12 in a toroidal shape and winding back around the bead core 14 arranged on the bead portion 12 from the inside to the outside, and is provided with at least one layer. The carcass ply 16 has a bias structure or a radial structure. In the illustrated example, the carcass ply 16 is a single layer, but is not limited thereto, and may be a plurality of layers.

  The belt layer 18 is located outside the carcass ply 16 in the tire radial direction, and is provided with at least one layer. An end 18A of the belt layer 18 in the tire width direction terminates between an end 20A on the tire equatorial plane side of the block row 20 located on the outermost side in the tire width direction and a center 20C in the width direction of the block row 20. Yes. The center 20C in the width direction is W / 2 from the end portion 20A on the tire equatorial plane CL side of the block row 20 on the tread tread surface 28, where W is the width of the block row 20 and the end opposite to the tire equatorial plane CL. The position is W / 2 from the portion 20B.

  In the illustrated example, the end 18A of the belt layer 18 terminates at the position of the center 20C in the width direction of the block row 20, but is not limited thereto, and the tire equatorial plane of the width direction center 20C and the block row 20 You may terminate in other positions between the end portion 20A on the CL side. Moreover, although the belt layer 18 is a single layer, the present invention is not limited to this, and a plurality of layers may be used.

  By setting the position of the end portion 18A in the belt layer 18 as described above, the cord output in the groove bottom 30 located in the outermost block row 20 in the tire width direction can be changed without changing the current block pattern design in the tread 26. Can be suppressed.

  In FIG. 2, the tread 26 includes a pattern (block pattern) that is located on the outer side of the belt layer 18 in the tire radial direction and includes a plurality of block rows 20, 22, and 24. In the groove portions of the block rows 22 and 24 in the tread 26, for example, depressions 34 are appropriately provided.

  The block rows 20 and 22 located on the outer side in the tire width direction have a larger number of blocks than the block row 24 located in the center portion in the tire width direction of the tread 26, and the total volume of the blocks is set larger. Yes.

  As described above, the block rows 20 and 22 located on the outer side in the tire width direction have a larger number of blocks than the block row 24 located on the center portion in the tire width direction of the tread 26, and the total volume of the blocks is larger. Since it is large, it is possible to improve steering stability while suppressing the occurrence of cording at the groove bottom 30 located in the outermost block row 20 in the tire width direction.

  In the example shown in FIG. 2, the block rows 20 and 22 and the block rows 22 and 24 are appropriately connected by the platform 32, but the end portion 18A of the belt layer 18 is disposed as in the present embodiment. In some cases, the platform 32 may not be provided. By not providing the platform 32, the rigidity of the block can be set low, and the depth of the groove 32 can be ensured to be larger, thereby improving the mud repellency and the handling stability such as a feeling of ground contact. Because it can.

  When the block pattern design is not originally provided with the platform 32, by setting the end portion 18A of the belt layer 18 as in the present embodiment, the outermost outermost portion in the tire width direction is not changed without changing the block pattern setting. It is possible to suppress the occurrence of the cord out at the groove bottom 30 located in the block row 20.

  Note that the block pattern of the tread 26 is not limited to the shape shown in FIG.

(Test example)
A tire for a motorcycle in which the end of the belt layer in the tire width direction is extended to the tread hump position is a conventional product, and the tire in a block row in which the end of the belt layer is positioned on the outermost side in the tire width direction A motorcycle tire terminated between the end portion on the equatorial plane side and the center in the width direction of the block row was evaluated as a product of the present invention under the conditions shown below and in Table 1. All of the test types are rear tires having a block pattern on the tread.

The test conditions are as follows.
・ Negative rate 80%
・ Block height 16mm
・ Tire size: 120/80
・ Inch diameter of tire: 19 inches ・ Rim for actual vehicle test: 2.15 × 19
・ Internal pressure for actual vehicle test: 80kPa

  In Table 1, the “bias ply structure” means that two carcass plies having a bias structure (aliphatic polyamide cords arranged in a direction of 30 ° with respect to the tire circumferential direction) are provided, and the carcass ply has an outer side in the tire radial direction. Is provided with a belt layer (monospiral belt using aramid: MSB).

  In addition, the “radial ply structure” means that one radial carcass ply (aliphatic polyamide cord is arranged in a direction of 90 ° with respect to the tire width direction) is provided, and the belt layer on the outer side in the tire radial direction of the carcass ply. (Mono spiral belt using aramid: MSB).

  Further, the tread gauge 1 is a tread thickness aimed at a tread gauge distribution similar to the conventional one, and the tread gauge 2 is a tread thickness when the rubber gauge is thickened so as not to generate a cord.

  As shown in Table 1, after the vulcanization of each tire, cords were found in the conventional test types 1 and 3, but in the present invention and other test types of the conventional products, Was not seen.

  Motorcycle tires related to each test type are mounted on a real vehicle and run on rough terrain by a professional rider. As shown in Table 2, grip feeling, grounding feeling, rigidity feeling and slipping related to steering stability are shown. Feeling evaluation was performed about each evaluation item of controllability. Each evaluation item has a maximum score of 10, and a larger value indicates a better result.

  According to this test example, test type 1 and test type 2, test type 3 and test type 4 have the same steering stability, but for test types 1 and 3, as shown in Table 1, Code out has occurred. Similarly, as shown in Table 1, in the test types 5 to 8, no code is generated, but all of these have large mass and poor steering stability. That is, only the test types 2 and 4 among the test types have no cord output, ensure good steering stability, and have a small mass.

DESCRIPTION OF SYMBOLS 10 Motorcycle tire 12 Bead part 14 Bead core 16 Carcass ply 18 Belt layer 18A End part 20 Block row | line | column located in the tire width direction outermost block (Block row | line | column located in the tire width direction outer side part)
20A End portion on the tire equatorial plane side 20C Center in the width direction 22 Block row located in the outer portion in the tire width direction 24 Block row located in the middle portion in the tire width direction 26 Tread 30 Groove bottom CL Tire equatorial surface

Claims (2)

At least one layer of carcass ply wound around the bead core disposed between the pair of bead portions in a toroidal shape from the inside to the outside, and at least one belt layer located on the outside in the tire radial direction of the carcass ply And a tread with a pattern comprising a plurality of block rows located outside the belt layer in the tire radial direction,
A tire for a motorcycle in which an end portion of the belt layer in the tire width direction terminates between an end portion on the tire equatorial plane side of a block row located on the outermost side in the tire width direction and a center in the width direction of the block row. . The automatic block according to claim 1, wherein the block row located on the outer side in the tire width direction has a larger number of blocks and the total volume of the blocks is larger than that on the tread in the tire width direction central portion. Tires for motorcycles.

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