JP2010221767A - Pneumatic tire for motorcycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire 2 for a motorcycle having excellent traction performance and steering stabilizing performance. <P>SOLUTION: The tire 2 includes a tread 4, a pair of sidewalls 6, a pair of beads 8, a carcass 10 laid over one bead 8 and the other bead 8, and a pair of cord groups 14 respectively positioned on the outside in an axial direction of the carcass 10. The cord group 14 is composed of a plurality of cords 36 successively disposed from a part near the beads 8 toward an end 22 of the tread 4 at intervals. Those cords 36 extend in a circumferential direction. The cord 36 positioned on the outermost side in a radial direction is positioned on the outer side in the radial direction than a position of a half of radial direction height to the end 22 of the tread 4. The cord 36 positioned on the innermost side in a radial direction is positioned on the inner side in the radial direction than the half position. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pneumatic tire mounted on a two-wheeled vehicle.

  A tire is configured by combining a number of members. By adjusting the specifications of these members, the rigidity of the tire is adjusted, and improvements in steering stability performance, traction performance, etc. are studied. An example of this study is disclosed in Japanese Patent Laid-Open No. 5-4503. In this publication, the specifications of the bead, carcass, belt and band are adjusted to improve the steering stability performance and durability during high-speed running.

Japanese Patent Laid-Open No. 5-4503

  Insufficient tire stiffness results in insufficient traction performance. Excessive rigidity hinders traction performance. There is an appropriate stiffness range that can exhibit sufficient traction performance. On the other hand, if the rigidity is adjusted with emphasis on traction performance, the rigidity may be insufficient and the steering stability performance may be reduced. It is not easy to achieve both traction performance and steering stability performance.

  An object of the present invention is to provide a pneumatic tire for a motorcycle that is excellent in traction performance and steering stability performance.

  The pneumatic tire for a motorcycle according to the present invention includes a tread whose outer surface forms a tread surface, a pair of sidewalls that extend substantially inward in the radial direction from the end of the tread, and each of which is more radial than the sidewall. A pair of beads positioned substantially inside, a carcass spanned between one bead and the other bead along the inside of the tread and sidewalls, and a pair of each positioned outside the carcass in the axial direction Code group. Each cord group is composed of a plurality of cords arranged in order at intervals from the vicinity of this bead toward the end of the tread. Each cord extends in the circumferential direction. The outermost cord in the radial direction is located radially outside the half of the radial height HT from the bead baseline to the end of the tread, and radially inward of the tread end. Is located. The cord located on the innermost side in the radial direction is located on the inner side in the radial direction from the half position. The number of these codes is 3 or more and 15 or less.

  Preferably, in this pneumatic tire for a two-wheeled vehicle, the ratio of the radial height H1 from the bead base line to the outermost cord in the radial direction to the radial height HT is 0.6 or more and 0.00. 9 or less. Preferably, the ratio of the radial height H2 from the bead base line to the innermost cord in the radial direction to the radial height HT is 0.1 or more and 0.4 or less. Preferably, the ratio of the radial distance H3 from the innermost cord in the radial direction to the outermost cord in the radial direction to the radial height HT is 0.3 or more and 0.7 or less. is there.

  Preferably, the cord is made of steel. The cord may be made of an aramid fiber or a nylon fiber. A cord made of an aramid fiber is particularly preferable. In this case, the configuration of this cord is preferably 1500 dtex / 2.

  In the pneumatic tire for a motorcycle according to the present invention, the cord group provided in the side wall portion can appropriately adjust the rigidity. This tire is excellent in traction performance and steering stability performance.

FIG. 1 is a cross-sectional view showing a part of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view showing a part of the tire of FIG.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

  The pneumatic tire 2 shown in FIG. 1 has a substantially bilaterally symmetric shape around the one-dot chain line CL in FIG. This alternate long and short dash line CL represents the equator plane of the tire 2. The tire 2 includes a tread 4, a sidewall 6, a bead 8, a carcass 10, a band 12, a cord group 14, and an inner liner 16. The tire 2 is a tubeless type. The tire 2 is attached to a two-wheeled vehicle. In FIG. 1, the vertical direction is the radial direction, the horizontal direction is the axial direction, and the direction perpendicular to the paper surface is the circumferential direction.

  The tread 4 is made of a crosslinked rubber having excellent wear resistance. The tread 4 has a shape protruding outward in the radial direction. The tread 4 includes a tread surface 18. The tread surface 18 is in contact with the road surface. A groove 20 is carved in the tread surface 18. The groove 20 forms a tread pattern. The groove 20 does not have to be cut into the tread 4.

  The sidewall 6 extends substantially inward in the radial direction from the end 22 of the tread 4. The sidewall 6 is made of a crosslinked rubber. The sidewall 6 absorbs an impact from the road surface by bending. Furthermore, the sidewall 6 prevents the carcass 10 from being damaged.

  The bead 8 is located substantially inward of the sidewall 6 in the radial direction. The bead 8 includes a core 24 and an apex 26 that extends radially outward from the core 24. The core 24 has a ring shape. The core 24 includes a plurality of non-stretchable wires (typically steel wires). The apex 26 is tapered outward in the radial direction. The apex 26 is made of a highly hard crosslinked rubber.

  The carcass 10 includes a first carcass ply 28 and a second carcass ply 30. The first carcass ply 28 and the second carcass ply 30 are spanned between the beads 8 on both sides, and are along the inside of the tread 4 and the sidewall 6. The first carcass ply 28 and the second carcass ply 30 are folded around the core 24 from the inner side to the outer side in the axial direction. The end 32 of the folded first carcass ply 28 is located on the radially outer side than the end 34 of the folded second carcass ply 30.

  Although not shown, the first carcass ply 28 and the second carcass ply 30 are composed of a large number of cords arranged in parallel and a topping rubber. The absolute value of the angle formed by each cord with respect to the equator plane is usually 70 ° to 90 °. In other words, the carcass 10 has a radial structure. The cord is usually made of organic fibers. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers. A carcass 10 having a bias structure may be employed.

  The band 12 is located outside the carcass 10 in the radial direction. The band 12 is located on the inner side in the radial direction of the tread 4. Although not shown, the band 12 is composed of a cord and a topping rubber. The cord extends substantially in the circumferential direction and is wound spirally. In the tire 2, the absolute value of the angle formed by the cord with respect to the equator plane is 5 ° or less, particularly 2 ° or less. In the present invention, the direction in which the absolute value of the angle formed with respect to the equator plane is 5.0 ° or less is the “substantially circumferential direction”. The band 12 has a so-called jointless structure. The band 12 can contribute to the rigidity of the tire 2 in the radial direction. In the tire 2, the influence of the centrifugal force acting during traveling is suppressed. The cord is usually made of organic fibers. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  FIG. 2 is an enlarged cross-sectional view showing a part of the tire 2 of FIG. In FIG. 2, the vicinity of the sidewall 6 of the tire 2 is shown. The cord group 14 is located in the vicinity of the sidewall 6. The cord group 14 is located outside the carcass 10 in the axial direction.

  The cord group 14 is composed of five cords 36. These cords 36 are arranged in order from the vicinity of the bead 8 toward the end 22 of the tread 4 at intervals. In the tire 2, the cord 36 a located on the outermost side in the radial direction is located on the outer side in the radial direction with respect to the end 32 of the folded first carcass ply 28. The cord 36 a is located radially inward from the end 22 of the tread 4. The cord 36b located on the innermost side in the radial direction is located on the radially inner side with respect to the tip 38 of the apex 26 of the bead 8.

  In the tire 2, each cord 36 extends in the circumferential direction. Each cord 36 constitutes a circle. Each circle formed by each cord 36 is concentric. The cord group 14 can effectively contribute to the rigidity of the tire 2.

  The number of the codes 36 included in the code group 14 is 3 or more and 15 or less. Since the number of the cords 36 is set to 3 or more, the cord group 14 can appropriately contribute to the rigidity, so that the traction performance and the steering stability performance of the tire 2 can be effectively improved. From this viewpoint, the number of the cords 36 is preferably five or more. By setting the number of the cords 36 to 15 or less, excessive rigidity is suppressed. In the tire 2, the traction performance is appropriately maintained. The tire 2 is excellent in traction performance and steering stability performance. In this respect, the number of the cords 36 is preferably 10 or less.

  In the tire 2, from the viewpoint that excessive rigidity can be suppressed and excellent traction performance can be maintained, the distance between one cord 36 and the other cord 36 adjacent to the one cord 36 is 1. 0 mm or more is preferable, 2.0 mm or more is more preferable, and 2.5 mm or more is particularly preferable. From the viewpoint that the cord group 14 appropriately contributes to the rigidity and an improvement in traction performance and steering stability performance is achieved, the distance is preferably 20 mm or less, more preferably 15 mm or less, and particularly preferably 7 mm or less. This interval is obtained by measuring the shortest distance from the outer surface of one cord 36 to the outer surface of another cord 36.

  In the tire 2, the cord 36 may be made of an organic fiber. The material of the cord 36 may be steel. From the viewpoint of weight reduction, the cord 36 made of organic fibers is preferable. Examples of the organic fiber include nylon fiber, polyester fiber, rayon fiber, polyethylene naphthalate fiber, and aramid fiber. Nylon fibers and aramid fibers are preferable from the viewpoint of effectively contributing to the rigidity of the tire 2. Particularly preferably, a cord 36 made of an aramid fiber is preferable. When the cord 36 is made of an aramid fiber, the configuration of the cord 36 is preferably 1500 dtex / 2 from the viewpoint that the cord 36 can effectively contribute to the rigidity of the tire 2.

  In FIG. 2, a solid line BBL represents a bead base line. This bead base line is a line that defines the rim diameter (see JATMA) of the rim on which the tire 2 is mounted. A double-headed arrow HT represents the height in the radial direction from the bead base line to the end 22 of the tread 4 of the tire 2. A solid line LA represents a position at which the radial height HT is halved.

  In the tire 2, the cord 36a located on the outermost side in the radial direction is located on the outer side in the radial direction with respect to the solid line LA. The cord 36b located on the innermost side in the radial direction is located on the inner side in the radial direction with respect to the solid line LA. The cord group 14 including such cords 36 can effectively contribute to the rigidity of the tire 2. The tire 2 is excellent in traction performance and steering stability performance.

  In FIG. 2, the double-headed arrow H1 represents the height in the radial direction from the bead 8 baseline up to the cord 36 located radially outward. A double-headed arrow H2 represents the height in the radial direction from the bead 8 baseline to the cord 36 located radially inward. A double-headed arrow H3 represents the radial height of the cord group 14.

  The ratio of the height H1 to the height HT is preferably 0.6 or more and 0.9 or less. By setting this ratio to be 0.6 or more, the cord group 14 can effectively contribute to the rigidity of the tire 2. The tire 2 is excellent in traction performance and steering stability performance. In this respect, the ratio is more preferably equal to or greater than 0.7. By setting this ratio to 0.9 or less, the rigidity of the tire 2 can be appropriately maintained. In the tire 2, both traction performance and steering stability performance can be maintained. In this respect, the ratio is more preferably equal to or less than 0.8.

  The ratio of the height H2 to the height HT is preferably 0.1 or more and 0.4 or less. By setting this ratio to 0.1 or more, the rigidity of the tire 2 can be appropriately maintained. In the tire 2, both traction performance and steering stability performance can be maintained. In this respect, the ratio is more preferably equal to or greater than 0.2. By setting this ratio to 0.4 or less, the cord group 14 can effectively contribute to the rigidity of the tire 2. The tire 2 is excellent in traction performance and steering stability performance. In this respect, the ratio is more preferably equal to or less than 0.3.

  In the tire 2, the height H1 is preferably 30 mm or greater and 45 mm or less. By setting the height H1 to 30 mm or more, the cord group 14 can effectively contribute to the rigidity of the tire 2. The tire 2 is excellent in traction performance and steering stability performance. From this viewpoint, the height H1 is more preferably 35 mm or more. By setting the height H1 to 45 mm or less, the rigidity of the tire 2 can be appropriately maintained. In the tire 2, both traction performance and steering stability performance can be maintained. In this respect, the height H1 is more preferably 40 mm or less.

  In the tire 2, the height H2 is preferably 5 mm or more and 25 mm or less. By setting the height H2 to be 5 mm or more, the rigidity of the tire 2 can be appropriately maintained. In the tire 2, both traction performance and steering stability performance can be maintained. From this viewpoint, the height H2 is more preferably 10 mm or more, and particularly preferably 15 mm or more. By setting the height H <b> 2 to 25 mm or less, the cord group 14 can effectively contribute to the rigidity of the tire 2. The tire 2 is excellent in traction performance and steering stability performance.

  In the tire 2, the height H3 is preferably 10 mm or greater and 40 mm or less. By setting the height H3 to be 10 mm or more, the cord group 14 can effectively contribute to the rigidity of the tire 2. The tire 2 is excellent in traction performance and steering stability performance. From this viewpoint, the height H3 is more preferably 15 mm or more, and particularly preferably 20 mm or more. By setting the height H3 to 40 mm or less, the rigidity of the tire 2 can be appropriately maintained. In the tire 2, excellent traction performance and steering stability performance can be maintained. In this respect, the height H3 is more preferably equal to or less than 35 mm, and particularly preferably equal to or less than 30 mm.

  In the present invention, the size and angle of each member of the tire 2 are measured in a state where the tire 2 is incorporated in a regular rim and the tire 2 is filled with air so as to have a regular internal pressure. At the time of measurement, no load is applied to the tire 2. In the present specification, the normal rim means a rim defined in a standard on which the tire 2 depends. “Standard rim” in the JATMA standard, “Design Rim” in the TRA standard, and “Measuring Rim” in the ETRTO standard are regular rims. In the present specification, the normal internal pressure means an internal pressure defined in a standard on which the tire 2 relies. “Maximum air pressure” in JATMA standard, “Maximum value” published in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in TRA standard, and “INFLATION PRESSURE” in ETRTO standard are normal internal pressures.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

[Example 1]
A pneumatic tire for a motorcycle according to Example 1 having the basic configuration shown in FIG. 1 and having the specifications shown in Table 2 below was obtained. The size of this tire is “210/60 R420”. In this tire, the cord group is composed of cords made of five aramid fibers. The configuration of this code was 1500 dtex / 2. The distance between the cords was 6 mm. The height HT in the radial direction to the end of the tread was 50 mm. In the cord group, the radial height H1 of the cord located on the outer side in the radial direction was set to 35 mm. The height H2 in the radial direction of the cord located on the inner side in the radial direction was set to 10 mm. The radial height H3 of the cord group was 25 mm.

[Example 2-12 and Comparative Example 4-8]
Number of cords, cord spacing, height H1, height H2, height H3, ratio of height H1 to height HT (H1 / HT), ratio of height H2 to height HT (H2 / HT) and Tires were obtained in the same manner as in Example 1 except that the ratio of the height H1 to the height HT (H3 / HT) was as shown in Tables 1 and 2 below.

[Examples 13 and 14]
A tire was obtained in the same manner as in Example 1 except that the type of cord was changed. The cord of Example 13 is nylon fiber. The configuration of this code is 940 dtex / 2. The material of the cord of Example 14 is steel. The wire diameter of this cord is 0.17 mm.

[Comparative Example 1]
A tire was obtained in the same manner as in Example 1 except that no cord group was provided. This comparative example 1 is a conventional tire used for racing.

[Comparative Example 2]
A tire was obtained in the same manner as in Example 1 except that the number of carcass plies constituting the carcass was two and no cord group was provided.

[Comparative Example 3]
A tire was obtained in the same manner as in Example 1 except that a reinforcing layer made of a crosslinked rubber was used instead of the cord group. The thickness of this reinforcing layer was 0.8 mm. The height in the radial direction from the bead base line to the end located on the radially outer side of the reinforcing layer was set to 35 mm. The radial height from the bead base line to the end located radially inward of the reinforcing layer was 10 mm. The complex elastic modulus of the reinforcing layer was 5 MPa. The complex elastic modulus was measured using a viscoelastic spectrometer (manufactured by Iwamoto Seisakusho Co., Ltd.) in accordance with the provisions of “JIS K 6394”. As measurement conditions, initial strain was 10%, amplitude was ± 1%, frequency was 10 Hz, deformation mode was tensile mode, measurement temperature was 70 ° C., and the length of the displacement part of the test piece was 30 mm. The test piece was cut out from the tire and had a length of 45 mm, a width of 4 mm, and a thickness of 2 mm.

[Running test]
A prototype tire was mounted on the rear wheel of a commercially available two-wheeled vehicle (4-cycle) with a displacement of 1000 cc. The rim was MT17 × 6.00, and the air pressure inside the tire was 200 kPa (cold). A commercially available conventional tire is mounted on the front wheel. The tire size of this front wheel is “125/80 R420”. The rim is MT17 × 3.50, and the tire air pressure is 140 kPa (cold). On a circuit course composed of dry asphalt roads, a ride test (sensory evaluation) on traction performance and steering stability performance by riders was conducted. The result is shown as an exponent value. Larger values indicate better results. The results are shown in Tables 1 and 2 below.

  As shown in Tables 1 and 2, the tires of the examples have a higher evaluation than the tires of the comparative examples. From this evaluation result, the superiority of the present invention is clear.

  The pneumatic tire described above can be applied to various vehicles.

2 ... tyre 4 ... tread 6 ... side wall 8 ... bead 10 ... carcass 12 ... band 14 ... cord group 24 ... core 26 ... apex 28. ..First carcass ply 30 ... Second carcass ply 36 ... Cord

Claims (7)

A tread whose outer surface forms a tread surface, a pair of sidewalls each extending substantially inward in the radial direction from an end of the tread, a pair of beads each positioned substantially inward in the radial direction from the sidewall, and the tread And a carcass spanned between one bead and the other bead along the inside of the sidewall, and a pair of cord groups each positioned on the outside in the axial direction of the carcass,
Each cord group consists of a plurality of cords arranged in order at intervals from the vicinity of this bead toward the end of the tread,
Each cord extends in the circumferential direction,
The outermost cord in the radial direction is located radially outside the half of the radial height HT from the bead baseline to the tread edge, and radially inward from the tread edge. Located in the
The innermost cord in the radial direction is located radially inward from the half position,
A pneumatic tire in which the number of these cords is 3 or more and 15 or less.   2. The pneumatic device according to claim 1, wherein a ratio of a radial height H <b> 1 from a bead base line to the outermost cord in the radial direction to a radial height HT is 0.6 or more and 0.9 or less. tire.   The ratio of the radial height H2 from the bead baseline to the innermost cord in the radial direction to the radial height HT is 0.1 or more and 0.4 or less. Pneumatic tire.   The ratio of the radial distance H3 from the innermost cord in the radial direction to the outermost cord in the radial direction to the radial height HT is 0.3 or more and 0.7 or less. The pneumatic tire according to any one of 1 to 3.   The pneumatic tire according to any one of claims 1 to 4, wherein a material of the cord is steel.   The pneumatic tire according to any one of claims 1 to 4, wherein the cord is made of an aramid fiber or a nylon fiber. The cord is made of aramid fiber,
The pneumatic tire according to claim 6, wherein the configuration of the cord is 1500 dtex / 2.

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