JP2017030564A - Pneumatic tire for motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve durability while maintaining steering stability of a tire.SOLUTION: In a reference state, when a region in a tire width direction in a step face of a tread, sandwiched between a position in the tire width direction of the step face of the tread separated by 50% of a half width of a periphery length of the step face of the tread along the periphery of the step face of the tread from a tire equator surface toward an end of the tread and a position in the tire width direction of the step face of the tread separated by 82% of the half width, is set as an intermediate region, branched grooves, which are constituted of at least one circumferential groove having a circumferential groove part provided in the intermediate region and at least one width-directional groove which has a width-directional groove part provided in the intermediate region and communicates with the circumferential groove in the intermediate region, are intermittently formed along a tire circumference direction in each half part of the tire, where at least one of width-directional grooves extends outward in the tire width direction more than an outer end in the tire width direction of the intermediate region.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire for a motorcycle.

  Conventionally, in pneumatic tires for motorcycles, particularly in running under a relatively high load, deterioration of tire durability due to damage at the belt end or ply end has been a problem. It was.

  The inventor believes that the cause of damage such as the belt end and ply end is that the temperature inside the tire near the ground contact end of the tire where the belt end or ply end can be located is generally high during traveling. And, it was found that promoting heat dissipation in such a portion is effective in improving the durability of the tire.

  Therefore, in order to improve the durability of the tire, it is considered effective to provide a recess such as a heat radiating groove in the vicinity of the ground end to reduce the temperature inside the tire near the ground end. However, if a groove is provided in the vicinity of the ground contact end, pattern noise may occur and the tire noise performance may be impaired.

  Therefore, an object of the present invention is to provide a pneumatic tire for a motorcycle that has improved durability while maintaining the noise performance of the tire.

The configuration of the present invention is as follows.
(1) The pneumatic tire for a motorcycle according to the present invention has a tire mounted on an applicable rim, filled with a specified internal pressure, and in a reference state in which no load is applied, from the tire equator surface to the tread end side, to the tread tread surface periphery. Along the tire width direction of the tread tread, sandwiched between the tire width direction position of the tread tread and the tire width direction position of the tread tread that is also 82% apart. When the region is an intermediate region, at least one circumferential groove provided in the intermediate region with a circumferential groove portion extending at an angle of 30 ° or less with respect to the tire circumferential direction, and in the tire width direction A widthwise groove portion extending at an angle of 30 ° or less with respect to the intermediate region, and at least one widthwise groove communicating with the circumferential groove in the intermediate region; Are formed intermittently along the tire circumferential direction in each of the tire halves, and at least one of the widthwise grooves is wider than the outer end of the intermediate region in the tire width direction. It extends to the outside in the direction.

  According to the pneumatic tire for a motorcycle of the present invention having such a configuration, durability can be improved while maintaining the noise performance of the tire.

The “applicable rim” is an industrial standard that is valid for the region where tires are produced and used. In Japan, JATMA (Japan Automobile Tire Association) JATMA YEAR BOOK, in Europe ETRTO (The European Tire) and Rim Technical Organization, Inc.) STANDARDS MANUAL, and in the United States, TRA (The Tire and Rim Association, Inc.) YEAR BOOK, etc., standard rims for applicable sizes (ETRTO STANDARDS MANUAL, Measuring Rim, TRA "YEAR BOOK" refers to Design Rim).
The “specified internal pressure” refers to the air pressure corresponding to the maximum load capacity in the applicable size and ply rating described in the above JATMA YEAR BOOK, etc. The “maximum load capacity” refers to the tire according to the above standards. The maximum mass allowed to be loaded.
Unless otherwise specified, all dimensions such as the length of the circumferential groove and the width groove are measured along the periphery of the tread surface.

(2) In the pneumatic tire for a motorcycle according to the present invention, it is preferable that a tire width direction length of the width direction groove is not less than 8% and not more than 30% of a half width of a peripheral length of the tread surface.
According to such a configuration, it is possible to further improve the durability of the tire while more reliably maintaining the steering stability and noise performance of the tire.

(3) In the pneumatic tire for a motorcycle of the present invention, it is preferable that a tire circumferential length of the circumferential groove is 20 mm or more and 80 mm or less.
According to such a configuration, it is possible to sufficiently obtain the heat dissipation effect by the circumferential groove while suppressing cracks at the groove bottom, and to further improve the durability of the tire.

(4) In the pneumatic tire for a motorcycle of the present invention, a value obtained by dividing the interval between the branch grooves adjacent in the tire circumferential direction by the pattern pitch length in the tire circumferential direction is 0.15 or more and 0.8 or less. Preferably there is.
According to such a configuration, it is possible to sufficiently obtain the heat dissipation effect by the branch groove while maintaining the steering stability, and to further improve the durability of the tire.

  In addition, "pattern pitch" means the tire circumferential direction length per unit of the tread pattern repeated in the tire circumferential direction, and when the tire circumferential direction length per unit changes in the tire circumferential direction, It shall mean the average length.

(5) In the pneumatic tire for a motorcycle of the present invention, the tire width direction position spaced from the tire equatorial plane to the tread end side by 50% of the half width of the peripheral length of the tread surface along the periphery of the tread surface; It is preferable that a negative rate in a tire width direction region between the tread end is 15% or more and 35% or less.
According to such a configuration, the durability of the tire can be further improved while more reliably maintaining the steering stability.

  The “negative rate” refers to the tire width direction position of the tread tread that is spaced from the tire equatorial plane to the tread end side by 50% of the peripheral width of the tread tread along the periphery of the tread tread. The ratio of the groove area in the tire width direction region to the area of the tread surface sandwiched between the tread ends {(groove area / tread surface area) × 100 (%)}.

(6) In the pneumatic tire for a motorcycle of the present invention, it is preferable that the number of the branch grooves formed on the tread surface is 20 or more and 60 or less.
According to such a configuration, the durability of the tire can be further improved while more reliably maintaining the steering stability.

(7) In the pneumatic tire for a motorcycle according to the present invention, the branch groove includes two widthwise grooves extending outwardly in the tire width direction from one end and the other end of the circumferential groove. It is preferably a U-shaped groove.
According to such a configuration, it is possible to further improve the durability of the tire while more reliably maintaining the steering stability and noise performance of the tire.

  According to the present invention, it is possible to provide a pneumatic tire for a motorcycle with improved durability while maintaining the noise performance of the tire.

1 is a sectional view in the tire width direction of a pneumatic tire for a motorcycle according to an embodiment of the present invention. Fig. 2 is a partial development view of a tread surface of the motorcycle pneumatic tire of Fig. 1. FIG. 3 is a partial development view of a tread surface of a pneumatic tire for a motorcycle according to another embodiment of the present invention.

Hereinafter, a pneumatic tire for a motorcycle (hereinafter, also simply referred to as “tire”) of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a cross section in the tire width direction of the tire according to an embodiment of the present invention in the above-described reference state (a state in which the tire is mounted on an applied rim, filled with a specified internal pressure, and is unloaded). This tire has a carcass 5 straddling between a pair of bead portions 11 as a skeleton, a pair of sidewall portions 12 on the outer side in the tire radial direction of the bead portions 11, and a tread portion 13 straddling between the sidewall portions 12. It has. In addition, although the carcass in this embodiment consists of one layer of plies, two or more layers of plies can be arranged. In the present embodiment, the inclined belt 3 including the two inclined belt layers 3a and 3b is disposed on the outer side in the tire radial direction of the carcass 5 in the tread portion 13. However, another belt structure may be used. . In the two inclined belt layers 3a and 3b, the respective cords are inclined with respect to the tire circumferential direction and extend so as to intersect each other.

FIG. 2 shows a part of the tread tread 6 of the tire of FIG. 1 according to the present embodiment. A part of the tread surface 6 is shown expanded. In the present embodiment, patterns that are line-symmetric with respect to the equator plane CL are arranged on the one side and the other side of the tread tread 6 with the tire equator plane CL as a boundary, and are shifted from each other in the tire circumferential direction X. ing. Therefore, the configuration of the tread tread 6 of this embodiment will be described as a representative of the left half of the tire toward the paper.
First, in this embodiment, the tire width direction position of the tread tread that is 50% apart from the tire equatorial plane CL toward the tread end TE side along the periphery of the tread tread 6 along the half width Lp of the peripheral length of the tread tread 6. Similarly, when the region in the tire width direction on the tread tread that is 82% apart and sandwiched between the tread treads in the tire width direction is an intermediate region A, at least one circumferential groove 1 ( In the illustrated example, a branch groove Br including one circumferential groove 1) and at least one width direction groove 2 (in the illustrated example, two width direction grooves 2a and 2b) is provided in each of the tire halves. It is formed intermittently along the tire circumferential direction. More specifically, the circumferential groove 1 includes a circumferential groove portion extending at an angle of 30 ° or less with respect to the tire circumferential direction in the intermediate region A, and the widthwise grooves 2a and 2b are tire widths. A widthwise groove portion extending at an angle of 30 ° or less with respect to the direction is provided in the intermediate region and communicated with the circumferential groove 1 in the intermediate region A.
The branch groove Br in the present embodiment has a width direction groove 2a extending from one end portion of the circumferential groove 1 toward the outer side in the tire width direction, and the other end portion of the circumferential groove 1 in the same direction. The width direction groove 2b extends, and both the width direction grooves 2a and 2b extend to the outer side in the tire width direction of the intermediate region A from the outer end in the tire width direction.

The circumferential groove 1 in the present embodiment is linear and extends along the tire circumferential direction. However, the circumferential groove 1 may be bent or curved, or the tire circumferential direction. And extend at an angle of 30 ° or less. Further, the width direction grooves 2a and 2b in the present embodiment are linear, have the same length, and extend while inclining with respect to the tire width direction. It can be bent or curved, or can extend along the tire width direction.
In addition to the branch grooves Br, lug grooves 4 are alternately formed on the tread surface 6 with the branch grooves Br along the tire circumferential direction. Both ends of the lug groove 4 terminate in the tread tread surface 6, but linear groove portions 4a, 4b, and 4c having different inclination angles with respect to the tire width direction are configured to communicate with each other. In other words, the lug groove 4 extends by being bent twice.
The lug groove 4 is a groove having a deeper groove depth than the circumferential groove 1 described above.

  Thus, in the tire according to the present invention, at least one circumferential groove 1 provided in the intermediate region A with a circumferential groove portion extending at an angle of 30 ° or less with respect to the tire circumferential direction; At least one widthwise groove that includes a widthwise groove portion that extends at an angle of 30 ° or less with respect to the tire width direction in the intermediate region A and communicates with the circumferential groove 1 in the intermediate region A. It is important that the branch groove Br consisting of 2 is formed intermittently along the tire circumferential direction in each of the tire halves.

  When such a branch groove Br is provided in the intermediate area A, the groove surface area in the intermediate area A where the amount of heat generated during traveling of the vehicle is maximized is increased in the vicinity of the ground contact TE. Can be promoted, and the temperature inside the tire in the vicinity of the ground contact TE can be lowered. Furthermore, if the groove area in the intermediate region A is increased, the volume of the rubber itself that causes heat generation is also reduced. Therefore, from the viewpoint of reducing the heat generation amount itself, the temperature inside the tire in the vicinity of the ground contact TE is also reduced. Can be reduced. As a result, the occurrence of failure at the belt end and the ply end can be suppressed, and the durability of the tire can be improved.

  However, when the groove provided in the intermediate region A terminates in the intermediate region A, the air taken into the groove during vehicle travel is confined between the tread surface and the road surface. Pattern noise occurs. More specifically, the tread tread surface 6 extends along the periphery of the tread tread surface 6 from the tire equator to the tread end side even when traveling with a relatively large inclination of the vehicle body when traveling under a heavy load. Therefore, the tread tread surface 6 tends to come into contact only with a position 82% apart from the half width Lp of the peripheral length, that is, near the outer end position in the tire width direction of the intermediate region A. Therefore, in the tire according to the present embodiment, the tire width direction end of the width direction groove 2 arranged in the intermediate region A is tire width direction outer side than the tire width direction outer side end of the intermediate region A, that is, the tire is more than the ground contact end. By extending to the outer side in the width direction, the air taken into the circumferential groove 1 and the width direction groove 2 can escape to the outside through the width direction groove 2. The tire width direction end of the width direction groove 2 from the tire equator to the tread end side along the periphery of the tread tread surface 6 from the position spaced 86% of the half width Lp of the peripheral length of the tread tread surface 6 More preferably, it extends to the outside. This 86% -separated position is equal to the ground contact edge when the vehicle body is tilted to the maximum when traveling under a heavy load, and the widthwise groove 2 is extended to the outside in the tire width direction from the position. The above effect 2 can be obtained more reliably.

  As described above, according to the configuration of the embodiment of the present invention, while maintaining the noise performance, the temperature inside the tire near the tread end is lowered as compared with the conventional one, thereby improving the durability of the tire. Can do.

In the present embodiment, from the viewpoint of obtaining a sufficient heat dissipation effect by the branch groove Br, the groove depths of the circumferential groove 1 and the width direction groove 2 constituting the branch groove Br are preferably 2 mm or more and 8 mm or less. .
When the thickness is 2 mm or more, a sufficient heat dissipation effect can be obtained, and when the thickness is 8 mm or less, steering stability can be maintained.
The “groove depth” in the present embodiment is the maximum depth from the groove opening position of the tread surface in the reference state.

  In the present embodiment, from the viewpoint of sufficiently reducing pattern noise, the tread tread 6 between the tire width direction outer end of the intermediate region A and at least one tire width direction outer end of the width direction groove 2 is used. The length in the tire width direction along the peripheral is preferably 15 mm or more.

  In the present embodiment, the traction performance of the tire can be improved by providing the lug grooves 4 described above. From the viewpoint of sufficiently improving the traction performance, the depth of the lug groove 4 is preferably 4 mm or more and 8 mm or less.

In the tire according to the present embodiment, the length in the tire width direction along the periphery of the tread surface 6 of the tread surface 6 of the width direction groove 2 is preferably 8% or more and 30% or less of the half width of the periphery length of the tread surface 6.
By setting the ratio to 8% or more, the durability of the tire can be further improved while maintaining the noise performance more reliably. By setting the ratio to 30% or less, the steering stability can be more reliably maintained. .

In the tire according to the present embodiment, the tire circumferential length along the peripheral of the tread surface 6 of the circumferential groove 1 is preferably 20 mm or more and 80 mm or less.
By setting it to 20 mm or more, a sufficient heat dissipation effect by the circumferential groove 1 can be obtained, and by setting it to 80 mm or less, generation of cracks at the groove bottom of the circumferential groove 1 can be suppressed.

In the tire according to the present embodiment, the value obtained by dividing the distance L between the branch grooves Br adjacent in the tire circumferential direction by the pattern pitch length in the tire circumferential direction may be 0.15 or more and 0.8 or less. preferable.
If it is 0.15 or more, the heat dissipation effect by the branch groove Br can be further improved, and if it is 0.8 or less, the steering stability of the tire can be more reliably maintained.

In the tire according to the present embodiment, the tire width direction position spaced from the tire equatorial plane CL toward the tread end TE side by 50% of the half width of the peripheral length of the tread tread surface 6 along the periphery of the tread tread surface 6; The negative rate in the tire width direction region between the tread end TE is preferably 15% or more and 35% or less.
If it is 15% or more, a sufficient heat dissipation effect can be obtained and the durability of the tire can be further improved, and if it is 35% or less, steering stability can be more reliably maintained.

In the tire according to this embodiment, the number of branch grooves Br formed on the tread surface 6 is preferably 20 or more and 60 or less.
If the number is 20 or more, a sufficient heat dissipation effect can be obtained by the branch groove Br, and the durability of the tire can be further improved. If the number is 60 or less, the steering stability can be more reliably maintained. . The number of branch grooves Br can be set as appropriate within the range of 20 to 60, for example, according to the length of the circumferential groove 1 described above.

  As described above, the branch groove Br in the present embodiment includes two width direction grooves 2a and 2b extending from one end and the other end of the circumferential groove 1 toward the outer side in the tire width direction. It is a U-shaped groove. According to this configuration, it is possible to further improve the durability of the tire while more reliably maintaining the steering stability and noise performance of the tire. However, in the tire according to the present invention, the branch groove Br is different from the other configurations. You can also

  For example, FIG. 3 shows another embodiment of the present invention. In the present embodiment, the same components as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted. In the tire according to the present invention, as shown in FIG. 3, the branch groove 3Br is divided into a circumferential groove 31, one end of the circumferential groove 31, the other end, and the outside in the tire width direction. It can also be comprised from three width direction groove | channels 32a, 32b, 32c extended toward.

  Examples of the present invention will be described below, but the present invention is not limited thereto. Invention tires and comparative tires (both tire sizes are 180 / 60R16M / C) were prototyped according to the specifications shown in Table 1, and the durability, noise performance and steering stability of the tires were evaluated.

  Each test tire has a carcass straddling between a pair of bead portions as a skeleton, and includes a pair of sidewall portions on the outer side in the tire radial direction of the bead portions, and a tread portion straddling the sidewall portions. More specifically, a carcass made of two layers of plies having nylon cords is provided, and two belt layers formed by rubber coating aramid cords on the outer side in the tire radial direction of the carcass, and on the outer side in the tire radial direction. A belt layer made of rubber coated nylon cord. The cord angle of the carcass ply with respect to the tire width direction is 15 °, the cord angle of each belt layer with respect to the tire circumferential direction is 15 °, and the cords of the two belt layers made of aramid cords cross each other between the layers. Yes.

Each test tire was assembled to an applicable rim (MT5.00-16 M / C), filled with an internal pressure of 280 kPa, and loaded with a STEP load, and run on a test drum at a speed of 81 km / h.
The durability of the tire was evaluated by the load until cracks occurred in the above test.
Tire noise performance evaluation and steering stability evaluation were performed by a test run with a professional test driver and feeling evaluation.

All the lengths shown in the table are the lengths along the periphery of the tread surface 6.
In the table, “the length (mm) of the outer end in the tire width direction of the width direction groove” is the length in the tire width direction of the end of the width direction groove 2 extending from the intermediate region A to the outer side in the tire width direction. That's it.
Further, “the length in the width direction groove in the tire width direction (%)” indicates the ratio of the length of the tread surface 6 of the width direction groove 2 to the half width Lp of the peripheral length of the tread surface 6.
Further, the “negative rate (%)” means the tread tread surface that is 50% apart from the tire equatorial plane CL toward the tread end TE side along the periphery of the tread tread surface 6 by a half width Lp of the peripheral length of the tread tread surface 6. The negative rate in the tire width direction region sandwiched between the tire width direction position and the tread end TE is shown.

  The results in Table 1 are indicated by an index with each result of Comparative Example Tire 1 being 100. The larger the index, the better the performance.

  1, 31: circumferential groove, 2, 2a, 2b, 2c, 32, 32a, 32b, 32c: width direction groove, 3: inclined belt, 3a, 3b: inclined belt layer, 4: lug groove, 5: carcass, 6: Tread surface, 7: Applicable rim, A: Intermediate region, Br, 3Br: Branch groove, CL: Tire equator surface, L: Tire circumferential interval between branch grooves, TE: Tread edge

Claims (7)

In the standard state where the tire is attached to the applicable rim, filled with the specified internal pressure, and no load is applied,
From the tire equator surface to the tread edge side, along the periphery of the tread surface, the tire width of the tread surface that is spaced by 50% of the half width of the peripheral length of the tread surface and the tire width direction position of the tread surface that is also 82% apart When the tire width direction area on the tread surface sandwiched between the directional positions is the intermediate area,
At least one circumferential groove provided in the intermediate region with a circumferential groove portion extending at an angle of 30 ° or less with respect to the tire circumferential direction, and at an angle of 30 ° or less with respect to the tire width direction. Each of the tire halves has a branch groove that includes a widthwise groove portion extending in an inclined manner in the intermediate region, and at least one widthwise groove communicating with the circumferential groove in the intermediate region. In, in the tire circumferential direction is formed intermittently,
A pneumatic tire for a motorcycle, wherein at least one of the widthwise grooves extends to the outer side in the tire width direction than the outer end in the tire width direction of the intermediate region.   The pneumatic tire for a motorcycle according to claim 1, wherein a length in the tire width direction of the width direction groove is 8% or more and 30% or less of a half width of a peripheral length of the tread surface.   The pneumatic tire for a motorcycle according to claim 1 or 2, wherein a tire circumferential length of the circumferential groove is 20 mm or more and 80 mm or less.   The value which remove | divided the space | interval between the said branching grooves adjacent to a tire circumferential direction by the pattern pitch length of a tire circumferential direction is 0.15 or more and 0.8 or less. The pneumatic tire for motorcycles described.   From the tire equatorial plane to the tread end side, the tire width direction position of the tread tread that is separated by 50% of the half width of the peripheral length of the tread tread along the periphery of the tread tread, and the tread end, The pneumatic tire for a motorcycle according to any one of claims 1 to 4, wherein a negative rate in a tire width direction region on a tread surface is 15% or more and 35% or less.   The pneumatic tire for a motorcycle according to any one of claims 1 to 5, wherein the number of the branch grooves formed on the tread surface is 20 or more and 60 or less.   The branching groove is a U-shaped groove including two widthwise grooves extending outward in the tire width direction from one end and the other end of the circumferential groove. The pneumatic tire for a motorcycle according to any one of claims 6.

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