JP2009113612A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire excellent in turning performance while maintaining straight advancement stability. <P>SOLUTION: The tire 2 is provided with a tread 4; a side wall 6; a bead 8; a carcass 10; a belt 12; and a reinforcement layer 14. The belt 12 is provided with a helically wound belt cord substantially extending in a circumferential direction. The reinforcement layer 14 is positioned at a shoulder and superposed on the belt 12. The reinforcement layer 14 comprises a cloth knitted with thread and a rubber covering the cloth. In the thread, an angle θ1 formed relative to a circumferential direction is 20°-70°. A ratio (W1/Wb) of the width W1 of the reinforcement layer relative to the width Wb of the belt is 0.10-0.40. In the tire of the other embodiment, the reinforcement layer 14 is positioned at the shoulder and superposed so as to clamp an end of the belt 12. An angle θ1 of the thread is 30°-60°. A ratio (W1/Wb) of the width W1 of the reinforcement layer relative to the width Wb of the belt is 0.05-0.40. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire.

  A pneumatic tire includes a tire including a belt in which a belt cord is spirally wound and extends substantially in the circumferential direction. This belt structure is called a jointless structure. Such a tire is excellent in disturbance absorbing performance during straight traveling. Such tires are excellent in straight running stability and durability during high speed running.

  Centrifugal force acts on the vehicle body when turning automobiles and motorcycles. For cornering, a cornering force that balances this centrifugal force is required. In a motorcycle, the rider tilts the motorcycle inward when turning. Turning is achieved by the camber thrust generated by this inclination. For the purpose of easy turning, motorcycle tires have a tread with a small radius of curvature. When going straight, the center area of the tread is grounded. On the other hand, when turning, the shoulder area of the tread is grounded.

  In a tire including a belt having a jointless structure, a belt cord extends in the circumferential direction. This tire has low tread axial continuity. This tire has low tread axial rigidity. Tires with low tread rigidity are inferior in turning performance. Tires with high tread rigidity are excellent in turning performance, but are inferior in disturbance absorbing performance during straight running.

Japanese Unexamined Patent Publication No. 2001-187514 discloses a tire with improved turning performance while maintaining straight running stability during high-speed running. This tire includes a belt wound in a spiral shape and a tread reinforcing layer in a shoulder region of the tread. The cord of the tread reinforcing layer has an angle of 70 ° to 90 ° with respect to the circumferential direction of the tire.
JP 2001-187514 A

  In the tire provided with the above-mentioned tread reinforcement layer, both turning performance and turning stability are compatible, but further improvement in turning performance is desired. In a tire with improved turning performance, the rigidity of the tread of the tire is increased and the straight running stability is likely to be reduced.

  An object of the present invention is to provide a pneumatic tire excellent in turning performance while maintaining straight running stability.

  A pneumatic tire 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 a pair positioned substantially inward in the radial direction from the sidewall. Bead, a carcass stretched between the beads along the inside of the tread and sidewalls, a belt laminated with the carcass inside the tread in the radial direction, and a belt positioned on the shoulder. And a pair of reinforcing layers. The belt includes a belt cord that is wound spirally and extends substantially in the circumferential direction. This reinforcing layer is made of a cloth formed by knitting yarn and rubber covering the cloth. This yarn has an angle of 20 ° to 70 ° with respect to the circumferential direction. The ratio (W1 / Wb) of the width W1 of the reinforcing layer to the width Wb of the belt is 0.10 or more and 0.40 or less.

  Preferably, the fineness of the yarn of the fabric is 400 dtex or more and 1000 dtex or less.

  Another pneumatic tire according to the present invention is 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 positioned substantially inward in the radial direction from the sidewall. A pair of 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 inner side of the tread, and a belt positioned on the shoulder And a pair of reinforcing layers stacked on the inner side and the outer side in the radial direction of the belt with the end in the axial direction interposed therebetween. This belt includes a belt cord wound in a spiral and extending substantially in the circumferential direction. This reinforcing layer is made of a cloth formed by knitting yarn and rubber covering the cloth. This yarn has an angle of 30 ° or more and 60 ° or less with respect to the circumferential direction. The ratio (W2 / Wb) of the width W2 of the reinforcing layer to the width Wb of the belt is 0.05 or more and 0.40 or less.

  Preferably, the fineness of the yarn of the fabric is 400 dtex or more and 1000 dtex or less.

  This tire has excellent disturbance absorbing performance when traveling straight. This tire exhibits high rigidity at the tread shoulder when turning. This tire is excellent in turning performance. This tire has excellent turning performance while maintaining straight running stability.

  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 with a one-dot chain line CL in FIG. 1 as a center line. 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 reinforcing layer 14, an inner liner 16 and a chafer 18. 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 may be carved in the tread surface 20. A tread pattern is formed by the groove being carved.

  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 22 and an apex 24 that extends radially outward from the core 22. The apex 24 is tapered outward in the radial direction. The apex 24 is made of a highly hard crosslinked rubber.

  The carcass 10 includes a carcass ply 26. The carcass ply 26 is stretched between the beads 8 on both sides, and extends along the inside of the tread 4 and the sidewall 6. The carcass ply 26 is folded around the core 22 from the inner side to the outer side in the axial direction. The carcass 10 may be composed of a plurality of carcass plies.

  Although not shown, the carcass ply 26 includes a plurality 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.

  The belt 12 is located on the radially outer side of the carcass 10. The belt 12 is made of a cord and a topping rubber. The cord is spirally wound and extends substantially in the circumferential direction. The angle formed by this cord with respect to the equator plane is 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 ° or less is the “substantially circumferential direction”. The belt 12 has a so-called jointless structure. 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. The belt 12 may be a belt in which a plurality of layers are stacked in the radial direction.

  The inner liner 16 is joined to the inner peripheral surface of the carcass 10. The inner liner 16 is made of a crosslinked rubber. For the inner liner 16, rubber having excellent air shielding properties is used. The inner liner 16 serves to maintain the internal pressure of the tire 2. The chafer 18 is located in the vicinity of the bead 8. When the tire 2 is assembled into a rim (not shown), the chafer 18 comes into contact with the rim. By this contact, the vicinity of the bead 8 is protected. The chafer 18 is usually made of cloth and rubber impregnated in the cloth. A chafer 18 made of a single rubber may be used.

  The reinforcing layer 14 is laminated on the belt 12 and positioned on the shoulder. In a belt in which a plurality of layers are stacked, the reinforcing layer 14 is laminated on any one of the layers.

  FIG. 2 is a cross-sectional view of a part of the reinforcing layer 14 of the tire 2 of FIG. The reinforcing layer 14 includes a cloth 32 formed by knitting a thread 30 and a thread 31 and a rubber 34 covering the cloth 32. Examples of the material of the yarn 30 and the yarn 31 include nylon fiber, polyester fiber, rayon fiber, polyethylene naphthalate fiber, and aramid fiber. The yarn 30 and the yarn 31 are in the form of a plain fabric that is alternately crossed. As shown in FIG. 2, the yarn 30 and the yarn 31 meander between each other. In FIG. 2, for the sake of convenience of explanation, the gap between the yarns 30 and 31 is widened. Has been. The fabric in the form of a plain woven fabric can obtain a substantially uniform rigidity improving effect over the entire surface.

  The yarns 30 and 31 having a large diameter contribute to improving the rigidity of the tire 2. From this viewpoint, the fineness of the yarn 30 and the yarn 31 is preferably 400 dtex or more. More preferably, it is 490 dtex or more.

  The thread 30 and 31 having a small diameter has a smaller meandering amount of the threads 30 and 31. A fabric having a small meandering amount of the yarns 30 and 31 has a small deformation amount. The reinforcing layer 14 provided with the fabric 32 having a small deformation amount contributes to improvement of the rigidity of the tire 2. From this viewpoint, the fineness of the yarns 30 and 32 is preferably 1000 dtex or less. More preferably, it is 800 dtex or less.

  FIG. 3 is a front view showing a part of the cloth 32 of the tire 2 of FIG. 1. The yarn 30 and the yarn 31 are inclined in opposite directions with respect to the circumferential direction. The yarn 30 and the yarn 31 are orthogonal to each other. The straight line L1 is the center line of the cloth 32. The straight line L1 is parallel to the circumferential direction. The straight line L2 is the direction of the yarn 30. The angle θ1 is an angle formed by the straight line L1 and the straight line L2. The angle θ1 is expressed by setting the inclination of the straight line L2 with respect to the straight line L1 as positive in the clockwise direction.

  This angle θ1 is set to 20 ° or more and 70 ° or less. Thereby, the rigidity of the tread 4 of the tire 2 is high. From this viewpoint, the angle θ1 is preferably 30 ° or more, and more preferably 40 ° or more. Similarly, from the viewpoint of increasing the rigidity of the tread 4, the angle θ1 is preferably 60 ° or less, and more preferably 50 ° or less.

  The straight line L3 is the direction of the yarn 31. The angle θ2 is an angle formed by the straight line L1 and the straight line L3. The angle θ2 is expressed with the inclination of the straight line L3 with respect to the straight line L1 as a positive counterclockwise direction.

  A double arrow Wb in FIG. 1 is a width from one end 36 of the belt 12 to the other end (not shown). The width Wb is measured along the surface of the belt 12 in a cross section perpendicular to the circumferential direction of the tire 2. A double-headed arrow W1 is a width from one end of the reinforcing layer 14 to the other end. The width W <b> 1 is measured along the surface of the reinforcing layer 14 in a cross section perpendicular to the circumferential direction of the tire 2. The ratio (W1 / Wb) of the width W1 of the reinforcing layer 14 to the width Wb of the belt 12 is 0.10 or more and 0.40 or less. By setting the ratio (W1 / Wb) to 0.10 or more, the effect of improving the rigidity of the shoulder region of the tread 4 can be obtained. In this respect, the ratio (W1 / Wb) is more preferably equal to or greater than 0.25. On the other hand, in the tire 2 in which the width W1 of the reinforcing layer 14 is narrow, the straight running stability is excellent. From this viewpoint, this ratio (W1 / Wb) is set to 0.40 or less. This ratio (W1 / Wb) is preferably 0.35 or less, and more preferably 0.30 or less.

  FIG. 4 is an enlarged cross-sectional view of a part of a pneumatic tire 38 according to another embodiment of the present invention. In FIG. 4, the reinforcing layer 14 is laminated on the inner side in the radial direction of the belt 12. In a motorcycle, the center region of the tread 4 is grounded when traveling straight ahead. When turning, the shoulder region of the tread 4 is grounded. In the tire 38, when the ground contact surface moves between the center region and the shoulder region, the discomfort given to the rider is alleviated. Other configurations are the same as those of the above-described one embodiment, and the description thereof is omitted.

  FIG. 5 is an enlarged cross-sectional view of a part of a pneumatic tire 40 according to still another embodiment of the present invention. Here, a configuration different from the tire 2 shown in FIG. 1 will be described. In the tire 40, as shown in FIG. 5, the reinforcing layer 14 sandwiches the end of the belt 12 in the axial direction. The reinforcing layer 14 is laminated on the inner side and the outer side of the belt 12 in the radial direction.

  In the tire 40, the angles θ <b> 1 and θ <b> 2 are measured by the reinforcing layer 14 positioned on the inner side in the radial direction of the belt 12. This angle θ1 is 30 ° or more and 60 ° or less. In the tire 40 having the angle θ1 of 30 ° or more, the reinforcing layer 14 can be easily folded back. From this viewpoint, the angle θ1 is preferably 35 ° or more, and more preferably 40 ° or more. Similarly, by setting the angle θ1 to 60 ° or less, the angle θ2 becomes 30 ° or more, and the reinforcing layer 14 can be easily folded back. From this viewpoint, the angle θ1 is preferably 55 ° or less, and more preferably 50 ° or less. On the radially outer side where the reinforcing layer 14 is folded back, the inclination of the yarn 30 is symmetric with respect to the inclination of the yarn 30 on the inner side in the radial direction and the circumferential direction. In the reinforcing layer 14, the radially inner yarn 30 and the radially outer yarn 30 are inclined in opposite directions at an angle θ 1 with respect to the circumferential direction. Similarly, the radially inner yarn 31 and the radially outer yarn 31 are inclined in opposite directions at an angle θ2 with respect to the circumferential direction.

  A double arrow W2 shown in FIG. 5 is the width of the belt 12 on which the reinforcing layer 14 is laminated. The width W2 is the width of the belt 12 in which the reinforcing layer 14 is laminated on the inner side and the outer side in the radial direction. The width W <b> 2 is measured along the surface of the belt 12 in a cross section perpendicular to the circumferential direction of the tire 40. The ratio (W2 / Wb) of the width W2 to the width Wb of the belt 12 is 0.05 or more and 0.40 or less. By making this ratio (W1 / Wb) 0.05 or more, it contributes to the rigidity improvement of the shoulder region of the tread 4. In this respect, the ratio (W2 / Wb) is preferably 0.10 or higher, and more preferably 0.20 or higher. On the other hand, the tire 40 having a narrow width W2 is excellent in straight running stability. From this viewpoint, the ratio (W2 / Wb) is set to 0.40 or less. This ratio (W2 / Wb) is preferably 0.35 or less,. 030 or less is more preferable.

  The belt 12 may be a belt in which a plurality of layers are stacked in the radial direction. In the tire in which the belt 12 is composed of a plurality of layers, the reinforcing layer 14 is laminated with the end of at least one of the layers sandwiched between the pair of reinforcing layers. The reinforcing layer 14 may be laminated by sandwiching the ends of a plurality of stacked layers with a pair of reinforcing layers.

  Here, a motorcycle tire has been described as an example, but the present invention can be similarly applied to a passenger car tire. The tire according to the present invention is excellent in the rigidity of the shoulder of the tread 4. This tire is excellent in turning performance. Since the tire includes the belt 12 having a jointless structure and the reinforcing layer 14, both linear stability and turning performance are achieved.

  In the present invention, unless otherwise specified, the size and angle of each member of the tire are measured in a state where the tire is incorporated in a normal rim and the tire is filled with air so as to have a normal internal pressure. During the measurement, no load is applied to the tire. In this specification, the normal rim means a rim defined in a standard on which a tire depends. “Standard rim” in the JATMA standard, “Design Rim” in the TRA standard, and “Measuring Rim” in the ETRTO standard are regular rims. In this specification, the normal internal pressure means an internal pressure defined in a standard on which the tire depends. “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. In the case of passenger car tires, the dimensions and angles are measured with an internal pressure of 180 kPa.

  Hereinafter, the effects of the 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 radial tire for a motorcycle of Example 1 having the basic structure shown in FIG. 1 and having the specifications shown in Table 1 below was obtained. The tire size is 120 / 70ZR17. The carcass consists of a single carcass ply. The cord used for the carcass ply is made of nylon fiber. The angle formed with respect to the equator plane of this cord is 90 °. The belt has a so-called jointless structure. The material of the belt cord is aramid fiber. The cord of the belt extends substantially in the circumferential direction. The material of the reinforcing layer yarn is nylon fiber. A pair of reinforcing layers are laminated on the outer side in the radial direction of the belt. The angle θ1 formed by the yarn with respect to the circumferential direction is 40 °.

[Examples 2 and 4 and Comparative Examples 1 and 2]
Tires of Examples 2 and 4 and Comparative Examples 1 and 2 were obtained in the same manner as Example 1 except that the angle θ1 of the reinforcing layer yarn was changed to the angle shown in Table 1.

[Example 3]
A tire of Example 3 was obtained in the same manner as in Example 1 except that a pair of reinforcing layers were laminated on the inner side in the radial direction of the belt, and the yarn angle θ1 of the reinforcing layer was changed to the angle shown in Table 1. .

[Examples 5 and 6 and Comparative Examples 3 and 4]
Tires of Examples 5 and 6 and Comparative Examples 3 and 4 in the same manner as in Example 1 except that the ratio (W1 / Wb) of the reinforcing layer width W1 to the belt width Wb is as shown in Table 2. Got.

[Comparative Example 5]
A tire of Comparative Example 5 was obtained in the same manner as in Example 1 except that the fineness of the reinforcing layer was 1400 dtex.

[Comparative Example 6]
As Comparative Example 6, a tire of Comparative Example 6 was obtained in the same manner as Example 1 except that no reinforcing layer was provided.

[Examples 7 to 9 and Comparative Examples 7 and 8]
The pair of reinforcing layers were configured to sandwich the belt as shown in FIG. The angle θ1 of the yarn of the reinforcing layer was set to the angle shown in Table 3. The ratio of the reinforcing layer width W2 to the belt width Wb (W2 / Wb) was as shown in Table 3. Other specifications were the same as in Example 1, and tires of Examples 7 to 9 and Comparative Example 8 were obtained. In Comparative Example 7 in which the angle θ1 was 25 °, it was difficult to reverse the reinforcing layer by sandwiching the belt, and a tire could not be manufactured.

[Examples 10 to 12 and Comparative Example 9]
The tires of Examples 10 to 12 and Comparative Example 9 were obtained in the same manner as in Example 7, except that the ratio (W2 / Wb) of the reinforcing layer width W2 to the belt width Wb was as shown in Table 4. It was.

[Cornering Force Evaluation]
The cornering forces generated by the tires of Examples 1 to 12 and Comparative Examples 1 to 6 and Comparative Examples 8 to 9 were measured. The cornering force generated when going straight and turning was measured. These tires were mounted on a motorcycle interior maneuverability tester. The tire air pressure is 290 kPa. The cornering force generated by applying a load of 1 kN was measured in a state where the tire inclination angle was 0 °. A cornering force with an inclination angle of 0 ° is a cornering force when going straight. Similarly, a cornering force with an inclination angle of 40 ° was measured. A cornering force with an inclination angle of 40 ° is a cornering force during turning. The measurement results are shown in Tables 1 to 4.

  As is apparent from the evaluation results, in the tires of Examples 1 to 12, the cornering force generated during turning is larger than that of the tire of Comparative Example 6 that is a commercially available tire. On the other hand, the cornering force of the tires of Examples 1 to 12 when traveling straight was equal to the cornering force of the tire of Comparative Example 6. The tires of Examples 1 to 12 have excellent maneuverability during turning and excellent disturbance absorption performance when traveling straight. The tire of Comparative Example 4 is excellent in maneuverability during turning, but is inferior in disturbance absorbing performance when traveling straight.

  As shown in Tables 1 to 4, the tires of the examples achieve both straight running stability and turning performance. From this evaluation result, the superiority of the present invention is clear.

  The radial tire according to the present invention can be mounted on various motorcycles and passenger cars.

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 a cross-sectional view of a part of the reinforcing layer of the tire of FIG. FIG. 3 is a front view showing a part of the tire cloth of FIG. 1. FIG. 4 is an enlarged cross-sectional view of a part of a pneumatic tire according to another embodiment of the present invention. FIG. 5 is an enlarged cross-sectional view of a part of a pneumatic tire according to still another embodiment of the present invention.

Explanation of symbols

2 ... Tire 4 ... Tread 6 ... Sidewall 8 ... Bead 10 ... Carcass 12 ... Belt 14 ... Reinforcement layer 16 ... Inner liner 18 ... Chafer 20 ... Tread surface 22 ... Core 24 ... Apex 26 ... Carcass ply 30 ... Thread 31 ... Thread 32 ... Cloth 34 ... Rubber 36 ... End 38 ...・ Tire 40 ... Tire

Claims (4)

A tread whose outer surface forms a tread surface,
A pair of sidewalls extending substantially inward in the radial direction from the ends of the tread;
A pair of beads positioned substantially radially inward of the sidewalls;
A carcass bridged between both beads along the inside of the tread and sidewall;
A belt laminated with the carcass on the inner side in the radial direction of the tread;
A pair of reinforcing layers positioned on the shoulder and stacked on the belt,
The belt includes a belt cord wound in a spiral and extending substantially in the circumferential direction;
This reinforcing layer consists of a fabric made of knitted yarn and rubber covering the fabric,
The angle formed by this thread with respect to the circumferential direction is 20 ° or more and 70 ° or less,
A radial tire in which the ratio (W1 / Wb) of the width W1 of the reinforcing layer to the width Wb of the belt is 0.10 or more and 0.40 or less.   The tire according to claim 1, wherein the fineness of the yarn of the cloth is 400 dtex or more and 1000 dtex or less. A tread whose outer surface forms a tread surface,
A pair of sidewalls extending substantially inward in the radial direction from the ends of the tread;
A pair of beads positioned substantially radially inward of the sidewalls;
A carcass bridged between both beads along the inside of the tread and sidewall;
A belt laminated with the carcass on the inner side in the radial direction of the tread;
A pair of reinforcing layers that are positioned on the shoulder and sandwiched between the inner side and the outer side in the radial direction of the belt with the axial end of the belt sandwiched therebetween,
The belt includes a belt cord wound in a spiral and extending substantially in the circumferential direction;
This reinforcing layer consists of a fabric made of knitted yarn and rubber covering the fabric,
The angle formed by this thread with respect to the circumferential direction is 30 ° or more and 60 ° or less,
A radial tire in which the ratio (W2 / Wb) of the width W2 of the reinforcing layer to the width Wb of the belt is 0.05 or more and 0.40 or less.   The tire according to claim 3, wherein the fineness of the yarn of the fabric is 400 dtex or more and 1000 dtex or less.

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