JP2009101719A - Pneumatic tire for motorcycle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire for a motorcycle having excellent transient characteristics and grounding feeling even during turning at a relatively large camber angle. <P>SOLUTION: A carcass 10 of a tire 2 has a carcass ply 28. The carcass ply 28 has a carcass cord 34. An absolute value of an angle θ1 of the carcass cord 34 with respect to the equatorial plane is set to be ≥60° and ≤90°. A belt 12 has a belt layer 38. The belt layer 38 has a belt cord 40. An absolute value of an angle θ2 of the belt cord 40 with respect to the equatorial plane is set to be ≥60° and ≤90°. A band 14 has a band layer 44. The band layer 44 has a band cord 46. An absolute value of an angle θ3 of the band cord 46 with respect to the equatorial plane is set to be ≤5°. A ratio (W2/W1) of the width W2 of the band layer 44 to the width W1 of the belt layer 38 is set to be ≥0.9 and <1.0. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention mainly relates to a pneumatic tire mounted on a motorcycle.

  Motorcycles are greatly tilted when turning. For this reason, motorcycle tires are required to have turning stability in addition to straight running stability. Furthermore, in recent years, motorcycles are also required to have high-speed running performance.

A conventional motorcycle tire includes a carcass, a belt, and a band. The band includes a band layer, and the band cord of the band layer is spirally wound around the tire equatorial plane. This band has a so-called jointless structure. This band suppresses kickback and shimmy. In this tire, the influence of centrifugal force during travel is suppressed. In this tire, no band joint appears in the running direction. This tire has excellent maneuverability and high speed durability for straight running.
Japanese Patent Laid-Open No. 5-4503

  In the tire, it is difficult to obtain a smooth turn-back or tilt-down movement at the time of transition between straight traveling and turning. In particular, when the camber angle becomes large, it is difficult to obtain a smooth turn-back or tilting movement. That is, this tire is inferior in excessive characteristics when the camber angle is increased. In addition, when turning with a large camber angle, the tire is inferior to the road surface. That is, this tire is also inferior in a grounding feeling.

  As a method for improving the transient characteristics and the feeling of ground contact, there is a method of increasing the gauge of the tread. For tires with a jointless belt, it is difficult to change the gauge by changing the design value. For this reason, it is difficult to improve the excessive characteristics and the feeling of grounding with the tread gauge. As another improvement method, a method by changing a tread surface pattern and a tire profile can be considered. These methods require modification of the mold, are expensive, and the modification period is long. These methods increase the development cost of the tire.

  An object of the present invention is to provide a pneumatic tire for a motorcycle that is excellent in excessive characteristics and a feeling of grounding even when turning at a relatively large camber angle.

  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 extending substantially inward in the radial direction from the end of the tread, and substantially radially inward of the sidewall. A pair of positioned beads, a carcass spanned between the beads along the inside of the tread and the sidewall, a belt laminated with the carcass on the radially outer side of the carcass, and between the belt and the tread And a band laminated on the outer side in the radial direction of the belt. The carcass has a carcass ply bridged between both beads. The carcass ply includes a carcass cord. The absolute value of the angle θ1 formed with respect to the equator plane of the carcass cord is 60 ° or more and 90 ° or less. The belt includes a belt layer. The belt layer includes a belt cord. The absolute value of the angle θ2 formed with respect to the equator plane of the belt cord is not less than 60 ° and not more than 90 °. The band includes a band layer. The band layer includes a band code. The band cord is spirally wound and extends substantially in the circumferential direction. The ratio (W2 / W1) of the width W2 of the band layer to the width W1 of the belt layer is 0.9 or more and less than 1.0.

  Preferably, in this tire, the ratio (W2 / W1) of the width W2 of the band layer to the width W1 of the belt layer is 0.97 or less. Preferably, the ratio (W2 / W1) is 0.93 or more.

  This tire provides a smooth turning or tilting movement between turning and rectilinear movement at a relatively large camber angle. That is, this tire is excellent in excessive characteristics and a feeling of ground contact at a relatively large camber angle.

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

  FIG. 1 is a cross-sectional view showing a part of a pneumatic tire 2 according to an embodiment of the present invention. 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 tire 2 has a substantially left-right symmetric shape centered on a 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 belt 12, a band 14, an inner liner 16 and a chafer 18. The tire 2 is a tubeless type. The tire 2 is attached to a motorcycle.

  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 20. The tread surface 20 is in contact with the road surface. A groove 22 is carved in the tread surface 20. The groove 22 forms a tread pattern. The groove 22 may not be cut on the tread surface 20.

  The sidewall 6 extends substantially inward in the radial direction from the end 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 carcass ply 28. The carcass ply 28 is bridged between the beads 8 on both sides, and extends along the inside of the tread 4 and the sidewall 6. The carcass ply 28 is folded around the core 24 from the inner side to the outer side in the axial direction. The carcass ply 28 includes a main body 30 and a pair of folded portions 32 continuous from both ends of the main body 30. The folded portion 32 extends outward in the radial direction. Two or three carcass plies may be used for the carcass 10. Both ends of the other one or two carcass plies of the carcass ply 28 may be bridged between the beats 8 on both sides, may be folded back, or may be stacked on the carcass ply 28 without reaching the beat 8.

  The belt 12 is laminated on the outer side in the radial direction of the carcass 10. The belt 12 reinforces the carcass 10. The belt 12 includes a belt layer 38.

  The band 14 is laminated on the outer side in the radial direction of the belt 12. The band 14 does not cover both ends of the belt 12 in the axial direction. Both ends in the axial direction of the belt 12 are laminated on the inner side in the radial direction of the tread 4. The band 14 includes a band layer 44.

  FIG. 2 is a plan view showing the carcass ply 28, the belt layer 38, and the band layer 44 of the tire 2 of FIG. The straight line L1 is the direction of the carcass cord 34 on the equator plane CL. The angle θ1 is an angle at which the equator plane CL and the straight line L1 intersect. The absolute value of the angle θ1 is not less than 60 ° and not more than 90 °. In other words, the carcass 10 has a radial structure.

  The carcass ply 28 includes a large number of carcass cords 34 and a topping rubber 36 arranged in parallel. The carcass cord 34 is usually made of an organic fiber. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  The belt layer 38 includes a large number of belt cords 40 and a topping rubber 42 arranged in parallel. Examples of the material of the belt cord 40 include nylon fiber, aramid fiber, polyethylene naphthalate fiber, polyester fiber, rayon fiber, glass fiber, carbon fiber, and steel. Preferred materials for the belt cord 40 include aramid fibers and steel.

  The straight line L2 is the direction of the belt cord 40 on the equator plane CL. The angle θ2 is an angle formed by the belt cord 40 with respect to the equator plane CL. The angle θ2 is set to 60 ° or more and 90 or less. By setting the angle θ2 to be large, the rigidity in the cross-sectional direction of the tire 2 in FIG. 1 is improved. By improving the rigidity in the cross-sectional direction, the tire 2 has improved turning stability. In this respect, the angle θ2 is preferably 70 ° or more, and more preferably 72 ° or more.

  The band layer 44 includes a band cord 46 and a topping rubber 48. The band cord 46 extends substantially in the circumferential direction. The band cord 46 is spirally wound. The band 14 has a so-called jointless structure. The band cord 46 is usually made of an organic fiber. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  The band layer 44 is made of a ribbon (not shown). This ribbon extends substantially in the circumferential direction and is wound spirally. It is easy to change the width of the band layer 44 by winding the ribbon spirally. The tire 2 provided with the band 14 of the jointless structure is excellent in straight running stability at high speed running. The straight line L3 is the direction of the band cord 46 on the equator plane CL. An angle θ3 (not shown) is an angle at which the equator plane CL and the straight line L3 intersect. The absolute value of the angle θ3 formed by the band cord 46 with respect to the circumferential direction is 5 ° or less, particularly 2 ° or less. In the present invention, the direction in which the absolute value of the angle θ3 formed with respect to the circumferential direction is 5 ° or less is the “substantially circumferential direction”.

  Examples of the material of the band cord 46 include nylon fiber, aramid fiber, polyethylene naphthalate fiber, polyester fiber, rayon fiber, glass fiber, carbon fiber, and steel. The band cord 46 having a high elastic modulus and high strength contributes to the straight running stability of the tire 2. From this viewpoint, the material of the band cord 46 is preferably aramid fiber or steel. Thereby, straight running stability and turning stability can be improved.

  A double arrow W <b> 1 in FIG. 1 indicates the width of the belt layer 38. Both ends of the belt layer 38 in the width direction are located at both ends in the axial direction. The width W1 of the belt layer 38 is an axial length along the surface of the belt layer from one end to the other end in the cross section of FIG. A double arrow W <b> 2 indicates the width of the band layer 44. The width W2 of the band layer 44 is an axial length along the surface of the band layer from one end to the other end in the cross section of FIG. In the tire 2, the width W <b> 2 of the band layer 44 is narrower than the width W <b> 1 of the belt layer 38.

  In the tire 2, kickback and shimmy are suppressed by the band layer 44. In this tire, no band joint appears in the running direction. Excellent maneuverability and high speed durability for straight running. From this viewpoint, the ratio (W2 / W1) is set to 0.9 or more. Preferably, the ratio (W2 / W1) is 0.93 or more.

  In general, in a conventional tire, both ends in the axial direction of the belt layer 38 are covered with a band layer 44 for the purpose of preventing belt lifting. In the tire 2, both axial ends of the belt layer 38 are not covered with the band layer 44. The tire 2 is excellent in excessive characteristics and a feeling of grounding when the camber angle is relatively large. The tire 2 is particularly excellent in excessive characteristics with a camber angle of 20 ° or more and a feeling of grounding. From this viewpoint, the ratio (W2 / W1) is set to less than 1.0. Preferably, the ratio (W2 / W1) is 0.97 or less.

  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 the JATMA standard, “maximum value” published in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in the TRA standard, and “INFLATION PRESSURE” in the 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 of Example 1 having the basic configuration shown in FIG. 1 and having the specifications shown in Table 1 below was obtained. The tire size is 180 / 55ZR17. In this tire, the angle θ1 formed by the carcass cord with respect to the equator plane is 82 °. The angle θ2 formed by the belt cord with respect to the equator plane is 82 °. The carcass cord and the belt cord are inclined symmetrically with respect to the equator plane. This tire has a band layer wound in the circumferential direction. The band layer band cord has an angle θ3 substantially 0 ° with respect to the equator plane. The material of the carcass cord is nylon fiber. The material of the belt cord and the band cord is aramid fiber.

[Examples 2 to 4]
Tires of Examples 2 to 4 were obtained in the same manner as in Example 1 except that the width W1 of the belt layer and the width W2 of the band layer were as shown in Table 1. The specifications of this tire are shown in Table 1 below.

[Comparative Example 1]
The angle θ1 formed by the carcass cord with respect to the equator plane was 90 °. The width W1 of the belt layer was 185 mm, and the width of the band layer was 200 mm. Others were the same as Example 1, and the tire of Comparative Example 1 was obtained. The specifications of this tire are shown in Table 1 below.

[Comparative Example 2]
The tire of Comparative Example 2 was obtained in the same manner as in Comparative Example 1 except that the width W1 of the belt layer was 215 mm and the width W2 of the band layer was 190 mm. The specifications of this tire are shown in Table 1 below.

[Running test]
The tire according to each of the above examples was attached to the rear wheel of a commercially available motorcycle. In this running test, a motorcycle with a displacement of 600 cc was used. The front wheel rim was set to “17 × MT3.50”. The air pressure of the front tire was 250 kPa. The tires of Examples 1 to 4 and Comparative Examples 1 and 2 were mounted on the rear wheel. The tire size of this rear wheel is 180 / 55ZR17. The rear wheel rim was set to “17 × MT5.50”. The air pressure of the rear tire was 290 kPa. Sensory evaluation by riders was performed on the asphalt road of the circuit course. Turning and straight running at a speed of 120 km / h were performed, and excessive characteristics and a feeling of ground contact were evaluated. The evaluation values are shown in Table 1 below. This evaluation shows that it is so favorable that a numerical value is high. An evaluation score of 4.0 is an acceptable limit.

[Measurement of spring constant]
FIG. 3 is a graph showing the relationship between the camber angle and the tire spring constant. The tires of Example 1 and Comparative Example 1 were incorporated into a regular rim of 17 × MT5.50, and the tire was filled with air to adjust the internal pressure to 290 kPa. The tire was grounded and the spring constant was measured by changing the camber angle from 0 ° to 45 ° every 9 °. In the measurement, a load of 5 kN was applied. The amount of vertical deflection of the tire due to the load was measured, and the spring constant was measured by dividing the load by the amount of deflection. The result is shown in FIG.

  It is not clear why the band layer width W2 is narrower than the belt layer width W1 to improve the excessive characteristics and the grounding feeling at a relatively large camber angle. As shown in FIG. 3, the tire of Example 1 has a larger spring constant with a measured value of a camber angle of 18 ° or more than the tire of Comparative Example 1. From this, it is presumed that this spring constant contributes to the improvement of the transient characteristics and the feeling of grounding at a relatively large camber angle.

  As shown in Table 1, the tires of the examples are excellent in excessive characteristics and a feeling of grounding. From this evaluation result, the superiority of the present invention is clear.

  The tire according to the present invention can be mounted on various motorcycles.

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 view showing a carcass ply, a belt layer, and a band layer of the tire of FIG. FIG. 3 is a graph showing the relationship between the camber angle and the constant of the spring tire.

Explanation of symbols

2 ... tyre 4 ... tread 6 ... side wall 8 ... bead 10 ... carcass 12 ... belt 14 ... band 16 ... inner liner 18 ... chafer 20 ... ..Tread surface 22 ... groove 24 ... core 26 ... apex 28 ... carcass ply 30 ... main body 32 ... folded portion 34 ... carcass cord 36 ... topping rubber 38 ... Belt layer 40 ... Belt cord 42 ... Topping rubber 44 ... Band layer 46 ... Band cord 48 ... Topping rubber

Claims (3)

A tread whose outer surface forms a tread surface, a pair of sidewalls extending substantially inward in the radial direction from the end of the tread, a pair of beads positioned substantially inward in the radial direction from the sidewall, and a tread and sidewalls A carcass stretched between the beads along the inside, a belt laminated with the carcass radially outside the carcass, and laminated between the belt and the tread and laminated radially outside the belt With a band,
The carcass has a carcass ply bridged between both beads,
This carcass ply has a carcass cord,
The absolute value of the angle θ1 formed with respect to the equator plane of the carcass cord is 60 ° or more and 90 ° or less,
The belt is provided with a belt layer;
This belt layer is equipped with a belt cord,
The absolute value of the angle θ2 formed with respect to the equator plane of the belt cord is 60 ° or more and 90 ° or less,
The band has a band layer,
This band layer has a band cord,
This band cord is spirally wound and extends substantially in the circumferential direction,
A pneumatic tire for a motorcycle, wherein a ratio (W2 / W1) of a width W2 of the band layer to a width W1 of the belt layer is 0.9 or more and less than 1.0.   The pneumatic tire for a motorcycle according to claim 1, wherein a ratio (W2 / W1) of the width W2 of the band layer to the width W1 of the belt layer is 0.97 or less.   The pneumatic tire for a motorcycle according to claim 1 or 2, wherein a ratio (W2 / W1) of the width W2 of the band layer to the width W1 of the belt layer is 0.93 or more.

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