JP2017121868A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire 22 in which rigidity in a circumferential direction is secured while suppressing occurrence of ply-steer.SOLUTION: In a tire 22, a reinforcement layer 38 comprises the first and second cut plies 56 and 58, and the first and second bands 60 and 62. The first cut ply 56 includes a first belt cord 72a, and the absolute value of an inclination angle in the first belt cord 72a is 40° or more but 70° or less. The second cut ply 58 includes a second belt cord 72b, and the absolute value of the inclination angle in the second belt cord 72b is equal to that in the first belt cord 72a. The first and second bands 60 and 62 include the first and second bad cords 76a and 76b substantially extending in a circumferential direction, respectively. The first band 60 is positioned outside the first cut ply 56, and the second cut ply 58 is positioned outside the first band 60. The second band 62 is located outside the second cut ply 58.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire.

  FIG. 4 shows an example of a reinforcing layer 38 of a conventional tire. The reinforcing layer 38 includes a belt 4, a band 6, and a pair of edge bands 8. In FIG. 4, an alternate long and short dash line CL represents the equator plane of the tire.

  The belt 4 is laminated with the carcass. The belt 4 includes an inner layer 10 and an outer layer 12. Each of the inner layer 10 and the outer layer 12 includes a number of cords 14 arranged in parallel. Each cord 14 is inclined with respect to the equator plane.

  The band 6 is located on the radially outer side of the belt 4. The band 6 covers the belt 4. The band 6 includes a cord 16 that extends substantially in the circumferential direction. The cord 16 of the band 6 is wound spirally.

  Each edge band 8 is located radially outside the belt 4 and in the vicinity of the end of the belt 4. The edge band 8 is located outside the band 6 in the radial direction. The edge band 8 includes a cord 18 extending substantially in the circumferential direction. The cord 18 of the edge band 8 is wound spirally.

  Tires step on the road. At this time, a contact surface is formed between the tire and the road surface. Depending on the ground contact shape of the tire, a portion having a high contact pressure and a portion having a low contact pressure appear on the contact surface. The height difference of the contact pressure formed on the contact surface affects the wear resistance and rolling resistance of the tire.

  The reinforcing layer 38 is located on the inner side in the radial direction of the tread. The tire steps on the road in the tread. The reinforcing layer 38 faces the road surface through the tread. The tread is more flexible than the reinforcing layer 38. The rigidity of the reinforcing layer 38 affects the ground contact shape of the tire.

  The tire is built into the rim, and the inside of the tire is filled with air. Thereby, the internal pressure of the tire is adjusted. The reinforcing layer 38 extends in the circumferential direction on the radially inner side of the tread. In order to stably maintain the tire form, the reinforcing layer 38 needs to have a certain degree of rigidity.

  In the tire, the reinforcing layer 38 is an important part. From the viewpoint of improving the performance of the tire, various studies have been made on the configuration of the reinforcing layer 38. An example of this study is disclosed in Japanese Patent Laid-Open No. 9-142104.

JP-A-9-142104

  In FIG. 4, the angle α <b> 1 represents the inclination angle of the cord 14 included in the inner layer 10. The angle α2 represents the inclination angle of the cord 14 included in the outer layer 12. As shown in FIG. 4, the inclination direction of the cord 14 of the inner layer 10 is opposite to the inclination direction of the cord 14 of the outer layer 12.

  The inclination angle α1 and the inclination angle α2 affect the coupling rigidity. When the absolute values of the inclination angle α1 and the inclination angle α2 approach 54.7 °, it is considered that the coupling rigidity becomes 0 and the price tear disappears. The fact that the price tear does not occur is advantageous in terms of improving cornering power, reducing rolling resistance, and improving wear resistance because no unnecessary force acts on the tire. However, in the belt 4 in which the absolute values of the inclination angle α1 and the inclination angle α2 are set to 54.7 °, there is a problem that sufficient circumferential rigidity cannot be secured. If sufficient circumferential rigidity cannot be ensured, the ground contact shape of the tire will be rounded, and the contact surface formed between the tire and the road surface will have a high contact pressure part and a low contact pressure part. End up. When the difference in the height of the contact pressure formed on the contact surface is increased, the wear resistance of the tire is lowered or the rolling resistance is increased. If the circumferential rigidity is insufficient, the tire strength may be insufficient.

  An object of the present invention is to provide a pneumatic tire in which circumferential rigidity is secured while suppressing the occurrence of price tear.

  The pneumatic tire according to the present invention includes a tread, a pair of sidewalls, a pair of beads, a carcass, and a reinforcing layer. Each sidewall extends substantially inward in the radial direction from the end of the tread. Each bead is located radially inward of the sidewall. The carcass is stretched between one bead and the other bead along the inside of the tread and the sidewall. The reinforcing layer is laminated with the carcass on the inner side in the radial direction of the tread. The reinforcing layer includes a first cut ply and a second cut ply, and a first band and a second band. The first cut ply includes a first belt cord extending inclined with respect to the equator plane. The absolute value of the inclination angle of the first belt cord is not less than 40 ° and not more than 70 °. The second cut ply includes a second belt cord extending inclined with respect to the equator plane. The inclination direction of the second belt cord is opposite to the inclination direction of the first belt cord. The absolute value of the inclination angle of the second belt cord is equal to the absolute value of the inclination angle of the first belt cord. The first band includes a first band cord extending substantially in the circumferential direction. The second band includes a second band cord extending substantially in the circumferential direction. In the radial direction, the first band is located outside the first cut ply. The second cut ply is located outside the first band. The second band is located outside the second cut ply.

  Preferably, in the pneumatic tire, the first band cord and the second band cord are made of organic fibers. The organic fiber is a nylon fiber or an aramid fiber.

  Preferably, in the pneumatic tire, the position of the end of the second band coincides with the position of the end of the first cut ply in the axial direction, or the end of the second band is the first band. It is located on the axially outer side than the end of the cut ply.

  Preferably, in this pneumatic tire, the distance from the end of the first cut ply to the end of the second band is 10 mm or less.

  In the pneumatic tire according to the present invention, the reinforcing layer includes the first cut ply and the second cut ply, and the first band and the second band. Each of the first cut ply and the second cut ply includes a belt cord extending inclined with respect to the equator plane, and the absolute value of the inclination angle of the belt cord is not less than 40 ° and not more than 70 °. The first cut ply and the second cut ply suppress the occurrence of price tear.

  Further, in this tire, each of the first band and the second band includes a band cord extending substantially in the circumferential direction, the first band is located outside the first cut ply, and the second cut ply is The second band is located outside the first cut band and the second band is located outside the second cut ply. In the conventional reinforcing layer, as shown in FIG. 4, the belt is restrained by a band and a pair of edge bands. In contrast, in the reinforcing layer of the present invention, the first cut ply is directly restrained by the first band, and the second cut ply is directly restrained by the second band. The configuration of the reinforcing layer contributes to the circumferential rigidity.

  Thus, in this tire, circumferential rigidity is ensured while suppressing the occurrence of price tear. In other words, according to the present invention, it is possible to obtain a pneumatic tire that secures circumferential rigidity while suppressing the occurrence of price tear. In the tire having this reinforcing layer, cornering power can be improved, rolling resistance can be reduced, and wear resistance can be improved while maintaining appropriate strength.

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 developed view schematically showing a part of the reinforcing layer of the tire of FIG. 1. FIG. 3 is a cross-sectional perspective view showing a part of the ribbon used for forming the first band of the tire of FIG. 1. FIG. 4 is a developed view schematically showing a part of a reinforcing layer of a conventional tire.

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

  FIG. 1 shows a pneumatic tire 22. In FIG. 1, the vertical direction is the radial direction of the tire 22, the horizontal direction is the axial direction of the tire 22, and the direction perpendicular to the paper surface is the circumferential direction of the tire 22. In FIG. 1, the alternate long and short dash line CL represents the equator plane of the tire 22. The shape of the tire 22 is symmetrical with respect to the equator plane except for the tread pattern.

  The tire 22 includes a tread 24, a pair of sidewalls 26, a pair of clinches 28, a pair of beads 30, a carcass 32, an inner liner 34, a pair of chafers 36, and a reinforcing layer 38. The tire 22 is a tubeless type. The tire 22 is attached to a passenger car.

  The tread 24 has a shape protruding outward in the radial direction. The tread 24 forms a tread surface 40 that contacts the road surface. A groove 42 is carved in the tread 24. The groove 42 forms a tread pattern. The tread 24 has a base layer 44 and a cap layer 46. The cap layer 46 is located on the radially outer side of the base layer 44. The cap layer 46 is laminated on the base layer 44. The base layer 44 is made of a crosslinked rubber having excellent adhesiveness. A typical base rubber of the base layer 44 is natural rubber. The cap layer 46 is made of a crosslinked rubber having excellent wear resistance, heat resistance, and grip properties.

  Each sidewall 26 extends substantially inward in the radial direction from the end of the tread 24. A radially outer portion of the sidewall 26 is joined to the tread 24. A radially inner portion of the sidewall 26 is joined to the clinch 28. The sidewall 26 is made of a crosslinked rubber having excellent cut resistance and weather resistance. This sidewall 26 prevents the carcass 32 from being damaged.

  The tire 22 is further provided with a wing 48 between the tread 24 and the sidewall 26. The wing 48 is joined to each of the tread 24 and the sidewall 26. The wing 48 is made of a crosslinked rubber having excellent adhesiveness.

  Each clinch 28 is located substantially inside the sidewall 26 in the radial direction. The clinch 28 is located outside the bead 30 and the carcass 32 in the axial direction. The clinch 28 is made of a crosslinked rubber having excellent wear resistance. The clinch 28 contacts the flange of a rim (not shown).

  Each bead 30 is located inside the clinch 28 in the axial direction. The bead 30 is located radially inward of the sidewall 26. The bead 30 includes a core 50 and an apex 52 that extends radially outward from the core 50. The core 50 is ring-shaped and includes a wound non-stretchable wire. A typical material for the wire is steel. The apex 52 is tapered outward in the radial direction. The apex 52 is made of a highly hard crosslinked rubber.

  The carcass 32 includes a carcass ply 54. In the tire 22, the carcass 32 includes a single carcass ply 54. The carcass 32 may be composed of two or more carcass plies 54.

  In the tire 22, the carcass ply 54 is stretched between the beads 30 on both sides, and extends along the tread 24 and the sidewalls 26. The carcass ply 54 is folded around the core 50 from the inner side to the outer side in the axial direction. By this folding, the carcass ply 54 is formed with a main portion 54a and a folding portion 54b.

  Although not shown, each carcass ply 54 includes 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 75 ° to 90 °. In other words, the carcass 32 has a radial structure. The cord is made of organic fiber. Examples of preferable organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  The inner liner 34 is located inside the carcass 32. The inner liner 34 is joined to the inner surface of the carcass 32. The inner liner 34 is made of a crosslinked rubber having excellent air shielding properties. A typical base rubber of the inner liner 34 is butyl rubber or halogenated butyl rubber. The inner liner 34 maintains the internal pressure of the tire 22.

  Each chafer 36 is located in the vicinity of the bead 30. When the tire 22 is incorporated into the rim, the chafer 36 comes into contact with the rim. By this contact, the vicinity of the bead 30 is protected. In this embodiment, the chafer 36 is made of cloth and rubber impregnated in the cloth. The chafer 36 may be integrated with the clinch 28. In this case, the chafer 36 is made of the same material as that of the clinch 28.

  The reinforcing layer 38 is located on the inner side in the radial direction of the tread 24. The reinforcing layer 38 is laminated with the carcass 32. The reinforcing layer 38 includes a first cut ply 56 and a second cut ply 58, and a first band 60 and a second band 62. Specifically, the reinforcing layer 38 includes a first cut ply 56 and a second cut ply 58, and a first band 60 and a second band 62.

  The first cut ply 56 constitutes a radially inner portion of the reinforcing layer 38. In the tire 22, the first cut ply 56 is laminated with the carcass 32. The first cut ply 56 continuously extends in a substantially axial direction from one end side of the tread 24 toward the other end side.

  In the tire 22, the first cut ply 56 is configured such that the axial width thereof is equal to the axial width of the belt in the conventional tire. That is, the axial width of the first cut ply 56 is preferably not less than 0.7 times the cross-sectional width of the tire 22 (see JATMA) and preferably not more than 0.9 times.

  The second cut ply 58 is located outside the first cut ply 56 in the radial direction. The second cut ply 58 extends continuously in a substantially axial direction from one end side of the tread 24 toward the other end side. In the tire 22, the width of the second cut ply 58 is smaller than the width of the first cut ply 56 in the axial direction. That is, the end 64 of the second cut ply 58 is positioned on the inner side in the axial direction than the end 66 of the first cut ply 56. In the tire 22, the length from the end 64 of the second cut ply 58 to the end 66 of the first cut ply 56 is preferably 3 mm or more, and preferably 15 mm or less. This length is more preferably 6 mm or more, and more preferably 9 mm or less.

  The first band 60 is located outside the first cut ply 56 in the radial direction. The first band 60 continuously extends in a substantially axial direction from one end side of the tread 24 toward the other end side. As apparent from FIG. 1, in the tire 22, the width of the first band 60 is larger than the width of the first cut ply 56 in the axial direction. That is, the end 68 of the first band 60 is located on the outer side in the axial direction than the end 66 of the first cut ply 56.

  In the tire 22, the first band 60 is located between the first cut ply 56 and the second cut ply 58 in the radial direction. In other words, the first band 60 is sandwiched between the first cut ply 56 and the second cut ply 58. In the tire 22, the first band 60 is laminated with the first cut ply 56, and the second cut ply 58 is laminated with the first band 60.

  The second band 62 constitutes a radially outer portion of the reinforcing layer 38. In the tire 22, the tread 24 is laminated on the second band 62.

  In the tire 22, the second band 62 is located outside the second cut ply 58 in the radial direction. The second band 62 continuously extends in a substantially axial direction from one end side of the tread 24 toward the other end side. As apparent from FIG. 1, in the tire 22, the width of the second band 62 is larger than the width of the first band 60 in the axial direction. That is, the end 70 of the second band 62 is located on the outer side in the axial direction than the end 68 of the first band 60. In the tire 22, the end 70 of the second band 62 may be located on the inner side in the axial direction than the end 68 of the first band 60.

  FIG. 2 is a development view schematically showing a part of the reinforcing layer 38 of the tire 22. In FIG. 2, the vertical direction is the circumferential direction of the tire 22, the horizontal direction is the axial direction of the tire 22, and the direction perpendicular to the paper surface is the radial direction of the tire 22.

  In the tire 22, the first cut ply 56 includes a large number of first belt cords 72a and a topping rubber 74a arranged in parallel. Each first belt cord 72a is inclined with respect to the equator plane. That is, the first cut ply 56 includes a first belt cord 72a that extends with an inclination to the equator plane. The density (the number of ends per 5 cm width) of the first belt cord 72a in the first cut ply 56 is set to the same density as that of a conventional tire belt.

  In the tire 22, a preferable material of the first belt cord 72a is steel. An organic fiber may be used for the first belt cord 72a like the cord of the carcass ply 54 described above.

  In FIG. 2, the angle α1 represents the inclination angle of the first belt cord 72a. In the tire 22, the absolute value of the inclination angle α1 of the first belt cord 72a is not less than 40 ° and not more than 70 °.

  In the tire 22, the second cut ply 58 is composed of a large number of second belt cords 72b and a topping rubber 74b arranged in parallel. Each second belt cord 72b is inclined with respect to the equator plane. That is, the second cut ply 58 includes a second belt cord 72b that extends while being inclined with respect to the equator plane. In the tire 22, the inclination direction of the second belt cord 72b is opposite to the inclination direction of the first belt cord 72a. Note that the density of the second belt cord 72b in the second cut ply 58 (number of ends per 5 cm width) is set to the same density as that of a conventional tire belt. In the tire 22, the density of the second belt cord 72b is the same as that of the first belt cord 72a.

  In the tire 22, a preferable material of the second belt cord 72b is steel. An organic fiber may be used for the second belt cord 72b like the cord of the carcass ply 54 described above.

  In the tire 22, the material of the second belt cord 72b is the same as that of the first belt cord 72a described above. A cord made of a material different from the material of the first belt cord 72a may be used for the second belt cord 72b. In the tire 22, a rubber equivalent to the topping rubber used in a conventional tire belt is used for the topping rubber 74 of each of the first cut ply 56 and the second cut ply 58.

  In FIG. 2, the angle α2 represents the inclination angle of the second belt cord 72b. In the tire 22, the absolute value of the inclination angle α2 of the second belt cord 72b is equal to the absolute value of the inclination angle α1 of the first belt cord 72a. As described above, the absolute value of the inclination angle α1 of the first belt cord 72a is not less than 40 ° and not more than 70 °. Therefore, the absolute value of the inclination angle α2 of the second belt cord 72b is also not less than 40 ° and not more than 70 °. In the present invention, when the difference between the absolute value of the inclination angle α2 and the absolute value of the inclination angle α1 is in the range of −2 ° or more and 2 ° or less, preferably the range of −1 ° or more and 1 ° or less. The absolute value of the inclination angle α2 is equivalent to the absolute value of the inclination angle α1.

  In the tire 22, the first band 60 includes a first band cord 76a and a topping rubber 78a. The first band cord 76a is wound spirally. The first band 60 has a so-called jointless structure. In the tire 22, the angle of the first band cord 76a with respect to the circumferential direction is 5 ° or less, and further 2 ° or less. The first band cord 76a extends substantially in the circumferential direction. That is, the first band 60 includes a first band cord 76a extending substantially in the circumferential direction. The density of the first band cord 76a in the first band 60 (the number of ends per 5 cm width) is set to the same density as that of a conventional tire band (full band).

  In the tire 22, the first band cord 76a is made of an organic fiber. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  In the tire 22, the second band 62 includes a second band cord 76b and a topping rubber 78b. The second band cord 76b is wound spirally. The second band 62 has a so-called jointless structure. In the tire 22, the angle of the second band cord 76b with respect to the circumferential direction is 5 ° or less, and further 2 ° or less. The second band cord 76b extends substantially in the circumferential direction. That is, the second band 62 includes a second band cord 76b extending substantially in the circumferential direction. Note that the density (number of ends per 5 cm width) of the second band cord 76b in the second band 62 is set to a density comparable to that of a conventional tire band (full band). In the tire 22, the density of the second band cord 76b is the same as that of the first band cord 76a.

  In the tire 22, the second band cord 76b is made of an organic fiber. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  In the tire 22, the material of the second band cord 76b is the same as that of the first band cord 76a described above. A cord made of a material different from that of the first band cord 76a may be used for the second band cord 76b. In the tire 22, rubber equivalent to the topping rubber used in the conventional tire band is used for the topping rubber 78 of each of the first band 60 and the second band 62.

  As described above, in the tire 22, the reinforcing layer 38 includes the first cut ply 56 and the second cut ply 58, and the first band 60 and the second band 62. Each of the first cut ply 56 and the second cut ply 58 includes a belt cord 72 extending inclined with respect to the equator plane, and the absolute value of the inclination angle of the belt cord 72 is not less than 40 ° and not more than 70 °. is there. The first cut ply 56 and the second cut ply 58 suppress the occurrence of price tear.

  Further, in the tire 22, each of the first band 60 and the second band 62 includes a band cord 76 extending substantially in the circumferential direction, and the first band 60 is located outside the first cut ply 56. The second cut ply 58 is located outside the first band 60 and the second band 62 is located outside the second cut ply 58. In the conventional reinforcing layer 2, the belt 4 is restrained by a band 6 and a pair of edge bands 8 as shown in FIG. 4. In this conventional reinforcing layer 2, the outer layer 12 is directly restrained by the band 6, but it is not the band 6 but the outer layer 12 that directly restrains the inner layer 10. On the other hand, in the reinforcing layer 38 of the present invention, the first cut ply 56 is directly restrained by the first band 60, and the second cut ply 58 is directly restrained by the second band 62. The configuration of the reinforcing layer 38 contributes to the rigidity in the circumferential direction.

  Thus, the first cut ply 56 and the second cut ply 58 suppress the occurrence of price tear, the first band 60 directly restrains the first cut ply 56, and the second band 62 directly restrains the second cut ply 58. By doing so, rigidity in the circumferential direction is ensured. In the tire 22, circumferential rigidity is ensured while suppressing the occurrence of price tear. According to the present invention, it is possible to obtain the pneumatic tire 22 in which the circumferential rigidity is ensured while suppressing the occurrence of price tear. In the tire 22 having the reinforcing layer 38, it is possible to improve cornering power, reduce rolling resistance, and improve wear resistance while maintaining appropriate strength.

  As described above, in the tire 22, the absolute value of the inclination angle α1 of the first belt cord 72a is not less than 40 ° and not more than 70 °, and the absolute value of the inclination angle α2 of the second belt cord 72b is not less than 40 ° and 70. ° or less. From the viewpoint that the first cut ply 56 and the second cut ply 58 effectively suppress the occurrence of price tear, the absolute value of the inclination angle α1 is preferably 45 ° or more, and preferably 65 ° or less. The absolute value of the inclination angle α2 is preferably 45 ° or more, and more preferably 65 ° or less. From the viewpoint that the occurrence of price tear is substantially suppressed, the absolute value of the inclination angle α1 is preferably 50 ° or more, and more preferably 60 ° or less. The absolute value of the inclination angle α2 is preferably 50 ° or more, and more preferably 60 ° or less. In the tire 22, the absolute value of the inclination angle α1 is particularly preferably 54.7 °, and the absolute value of the inclination angle α2 is particularly preferably 54.7 °. By setting the absolute values of the inclination angle α1 and the inclination angle α2 to 54.7, the price tear becomes “0 (zero)”.

  As described above, in the tire 22, examples of preferable organic fibers for the first band cord 76a include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers. From the viewpoint of the rigidity in the circumferential direction of the tire 22, an aramid fiber is more preferable as the organic fiber. Nylon fiber is more preferable as the organic fiber from the viewpoint of having appropriate elongation and excellent versatility.

  As described above, in the tire 22, examples of preferable organic fibers for the second band cord 76b include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers. From the viewpoint of the rigidity in the circumferential direction of the tire 22, the organic fiber is more preferably an aramid fiber. Nylon fiber is more preferable as the organic fiber from the viewpoint of having appropriate elongation and excellent versatility.

  The tire 22 is incorporated in a rim. The inside of the tire 22 is filled with air, and the internal pressure of the tire 22 is adjusted. At this time, the first band 60 and the second band 62 of the tire 22 are extended in the circumferential direction. As a result, tension acts on the first band cord 76 a of the first band 60 and the second band cord 76 b of the second band 62. When a high pressure is set as the internal pressure of the tire 22, the band cord 76 needs to be stretched to some extent in order to suppress breakage of the band cord 76. From the viewpoint of elongation of the band cord 76, nylon fiber is more preferable as the organic fiber for the first band cord 76a. As the organic fiber for the second band cord 76b, nylon fiber is more preferable.

  In FIG. 1, a double-headed arrow L represents the distance from the end 66 of the first cut ply 56 to the end 70 of the second band 62.

  In the tire 22, the position of the end 70 of the second band 62 coincides with the position of the end 66 of the first cut ply 56 in the axial direction. It is preferable to be located on the outer side in the axial direction from the end 66 of the cut ply 56. In other words, the distance L from the end 66 of the first cut ply 56 to the end 70 of the second band 62 is preferably 0 mm or more. By setting the distance L to be 0 mm or more, not only the first band 60 but also the second band 62 contributes to the restraint of the first cut ply 56. In the tire 22, sufficient circumferential rigidity is ensured. From this viewpoint, the distance L is more preferably 3 mm or more.

  In the tire 22, the distance L is preferably 10 mm or less. By setting the distance L to 10 mm or less, the influence on the mass by the second band 62 is suppressed. In the tire 22, a small rolling resistance is maintained. In this respect, the distance L is more preferably 7 mm or less.

  As described above, in the tire 22, the end 68 of the first band 60 is positioned on the outer side in the axial direction than the end 66 of the first cut ply 56. In the tire 22, the position of the end 70 of the second band 62 coincides with the position of the end 66 of the first cut ply 56 in the axial direction. If the first band 60 is positioned on the outer side in the axial direction than the end 66 of the cut ply 56, the end 68 of the first band 60 is the end of the first cut ply 56 in order to suppress the influence of the first band 60 on the mass. It may be located on the inner side in the axial direction than 66. In this case, from the viewpoint of restraining the first cut ply 56 by the first band 60, the end 68 of the first band 60 has an end 66 of the first cut ply 56 and an end of the second cut ply 58 in the axial direction. Preferably, it is located between 64. On the other hand, in order to sufficiently restrain the first cut ply 56 by the first band 60, when the end 68 of the first band 60 is arranged on the axially outer side than the end 66 of the first cut ply 56, In order to suppress the influence of the first band 60 on the mass, the end 68 of the first band 60 is preferably located on the inner side in the axial direction than the end 70 of the second band 62.

  In the tire 22, cords made of organic fibers are preferably used for the first band cord 76a and the second band cord 76b. In the present invention, the thickness of the cord made of organic fibers is represented by fineness. This cord may be formed by twisting a plurality of filaments instead of a single filament. For example, when the cord is formed using two filaments having a fineness of 1400 dtex, the configuration of the cord is represented by 1400 dtex / 2. In this case, the thickness of the cord is expressed by the product (1400 × 2 = 2800) of the fineness of the filament and the number of filaments.

  In the tire 22, when the first band cord 76a is made of an organic fiber, the thickness of the first band cord 76a is preferably 800 dtex or more, and preferably 6300 dtex or less. By setting the thickness to 800 dtex or more, the first band 60 including the first band cord 76a effectively restrains the first cut ply 56. In the tire 22, sufficient circumferential rigidity is ensured. By setting the thickness to 6300 dtex or less, the influence on the rolling resistance by the first band 60 is effectively suppressed. In the tire 22, a small rolling resistance is maintained.

  In the tire 22, when the second band cord 76b is made of an organic fiber, the thickness of the second band cord 76b is preferably 800 dtex or more, and preferably 6300 dtex or less. By setting the thickness to 800 dtex or more, the second band 62 including the second band cord 76b effectively restrains the second cut ply 58. In the tire 22, sufficient circumferential rigidity is ensured. By setting the thickness to 6300 dtex or less, the influence on the rolling resistance by the second band 62 is effectively suppressed. In the tire 22, a small rolling resistance is maintained.

  The present inventors have examined the contribution of the reinforcing layer 38 to the circumferential rigidity, and if the first band 60 is directly restrained by the first cut ply 56, the second band cord 76b of the second band 62 is obtained. In this case, sufficient rigidity in the circumferential direction can be obtained even if a cord thinner than the first band cord 76a of the first band 60 is used. In this case, the knowledge that the rolling resistance can be further reduced is obtained. Has reached. The following effects are based on this finding.

  In the tire 22, the ratio of the thickness of the second band cord 76b to the thickness of the first band cord 76a is preferably 90% or less. Thereby, a smaller rolling resistance is achieved while appropriately maintaining the rigidity in the circumferential direction. In this respect, the ratio is more preferably equal to or less than 80%. In the tire 22, this ratio is preferably 50% or more. Thereby, the restraining force of the second cut ply 58 by the second band 62 is appropriately maintained. Since the circumferential rigidity is ensured, the tire 22 has an appropriate strength. In this respect, the ratio is more preferably equal to or greater than 60%.

  The tire 22 described above is manufactured as follows. In manufacturing the tire 22, a plurality of rubber members are assembled to obtain a raw cover (unvulcanized tire 22). This raw cover is put into a mold. The outer surface of the raw cover is in contact with the cavity surface of the mold. The inner surface of the raw cover contacts the bladder or the core. The raw cover is pressurized and heated in the mold. The rubber composition of the raw cover flows by pressurization and heating. The rubber causes a crosslinking reaction by heating, and the tire 22 is obtained.

  In the manufacture of the tire 22, the ribbon 80 shown in FIG. 3 is used to form the first band 60 and the second band 62. In the ribbon 80, a plurality of band cords 76 arranged in parallel are covered with a wrapping rubber 78. The width of the ribbon 80 (the double-headed arrow W in FIG. 3) is usually set as appropriate in the range of 5 mm to 30 mm.

  In the manufacture of the tire 22, the first band 60 is formed by winding the ribbon 80 substantially spirally in the circumferential direction. The second band 62 is also formed by winding the ribbon 80 substantially spirally in the circumferential direction. The ribbon 80 for the second band 62 may have the same configuration as the configuration of the ribbon 80 for the first band 60, or may have a different configuration.

  In the manufacture of the tire 22, the ribbon 80 is wound at a constant pitch when the first band 60 or the second band 62 is formed. In order to obtain an appropriate grounding shape, it is preferable that the reinforcing layer 38 has uniform rigidity as a whole. From this point of view, in the formation of the first band 60 or the second band 62, it is preferable that the above-described pitch is set to coincide with the width of the ribbon 80 so that the ribbon 80 can be wound with less density.

  In the manufacture of the tire 22, tension is applied to the ribbon 80 in forming the first band 60 or the second band 62. As described above, in order to obtain an appropriate ground contact shape, it is preferable that the reinforcing layer 38 has uniform rigidity as a whole. From this viewpoint, it is preferable that the tension is kept constant in the formation of the first band 60 or the second band 62. Further, the large tension affects the retention of the raw cover. From this viewpoint, the tension is preferably 200 N or less. With a small tension, it is difficult to form the first band 60 or the second band 62. From the viewpoint of easy formation of the first band 60 or the second band 62, the tension is preferably 10 N or more. This tension is represented by a force applied to one band cord 76 included in the ribbon 80.

  In the present invention, the size and angle of each member of the tire 22 are measured in a state where the tire 22 is incorporated in a regular rim and the tire 22 is filled with air so as to have a regular internal pressure. During the measurement, no load is applied to the tire 22. In the case of the passenger car tire 22, the dimensions and angles are measured in a state where the internal pressure is 180 kPa.

  In the present specification, the normal rim means a rim defined in a standard on which the tire 22 relies. “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 22 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.

  In the present specification, the normal load means a load defined in a standard on which the tire 22 relies. “Maximum value” published in “Maximum load capacity” in the JATMA standard, “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in the TRA standard, and “LOAD CAPACITY” in the ETRTO standard are normal loads.

  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]
The tire shown in FIG. 1-2 was manufactured. The size of this tire is 235 / 50R18. The specifications of this tire are as shown in Table 1 below.

  In Example 1, the first band was formed by winding a ribbon from one end of the first band to the other end with a constant tension (20 N). The second band was also formed by winding a ribbon from one end of the second band to the other end with a constant tension (20 N). This is indicated by “20/20” in the “Tension (Sh / Cr)” column of Table 1. “Sh” represents the tension when the shoulder portion corresponding to the end portion of the first band or the second band is formed, and “Cr” corresponds to the equatorial plane portion of the first band or the second band. It represents the tension when the crown portion is formed. The coupling rigidity obtained based on the inclination angle α1 of the first belt cord and the inclination angle α2 of the second belt cord is an index, and is described in the “Coupling” column of Table 1.

[Comparative Example 1-6]
The tire of Comparative Example 1-6 was obtained in the same manner as in Example 1 except that the reinforcing layer had the configuration shown in FIG. 3 and the inclination angle α1 and inclination angle α2 were as shown in Table 1 below. It was. A cord made of nylon fiber was used for the band cord. The configuration of this band code was 1400 dtex / 2.

  In Comparative Example 1-6, this band was formed by winding a ribbon from one end of the band to the other end with a constant tension (20 N).

[Comparative Example 7-8]
A tire of Comparative Example 7-8 was obtained in the same manner as Comparative Example 5 except that the material of the band cord was changed as shown in Table 2 below. The configuration of the band cord of Comparative Example 7 was “3 × 3 × 0.17”. The configuration of the band cord of Comparative Example 8 was “1670 dtex / 2”.

[Example 2-4]
A tire of Example 2-4 was obtained in the same manner as in Example 1 except that the distance L from the end of the first cut ply to the end of the second band was as shown in Table 2 below.

[Example 5-8]
A tire of Example 5-8 was obtained in the same manner as in Example 1 except that the tension of the ribbon in forming the first band and the second band was changed as shown in Table 3 below.

[Example 9-11]
Example 2 is the same as Example 1 except that the configuration of the second band cord is changed and the ratio of the thickness of the second band cord to the thickness of the first band cord is as shown in Table 4 below. A tire 9-11 was obtained.

[Example 12]
A tire of Example 12 was obtained in the same manner as Example 1 except that a cord made of aramid fibers (configuration = 1670 dtex / 2) was used for the first band cord and the second band cord.

[Pressure resistance]
The tire was assembled in a rim (size = 18 × 7.5 J), water was poured into the tire so that the internal pressure was 600 kPa in a water tank, and the tire was allowed to stand for 24 hours. After that, water was further injected to measure the pressure at which the tire breaks. The result is an index and is shown in Table 1-4 below. The larger the value, the higher the strength of the tire.

[Plunger test]
The plunger test was performed as follows. First, the tire was assembled in a rim (size = 18 × 7.5 J), and this tire was filled with air so that the internal pressure was 220 kPa. The tire was destroyed by pressing a plunger (plunger diameter = 19 mm) against the tread surface and moving the plunger from the outside toward the inside in the radial direction. In this destruction, the force required for the plunger to push in the tire (hereinafter referred to as pushing force) and the amount of movement of the plunger were measured. Evaluation on the strength of the tire was performed based on the pushing force and the movement amount immediately before the tire broke. The result is an index and is shown in Table 1-4 below. The larger the value, the higher the strength of the tire.

[Cornering power (CP)]
Using a flat belt type tire 6 component force measuring device, cornering power was measured under the following measurement conditions.
Rim used: 18 × 7.5J
Internal pressure: 230 kPa
Load: 5.69kN
Speed: 10km / h
Camber angle: 0 °
Slip angle: 1 °
The result is an index and is shown in Table 1-4 below. The larger the numerical value, the greater the cornering power.

[Rolling resistance coefficient (RRC)]
Using a rolling resistance tester, the rolling resistance coefficient was measured under the following measurement conditions.
Rim used: 18 × 7.5J (made of aluminum alloy)
Internal pressure: 250 kPa
Load: 6.47kN
Speed: 80km / h
The result is an index and is shown in Table 1-4 below. A smaller numerical value is preferable because the rolling resistance coefficient is smaller.

[Wear energy]
About the tire, the shear force and displacement of the tire surface were measured on the following conditions with the sensor embedded in the road surface part of this testing machine using the flat plate testing machine by Showa Denki Seisakusho, and the wear energy was obtained. The result is an index and is shown in Table 1-4 below. The smaller the value, the smaller the wear energy and the better.
Rim used: 18 × 7.5J (made of aluminum alloy)
Internal pressure: 230 kPa
Load: 5.69kN

  As shown in Table 1-4, the tire of the example has a higher evaluation than the tire of the comparative example. From this evaluation result, the superiority of the present invention is clear.

  The technology relating to the reinforcing layer described above can be applied to various types of tires.

2, 38 ... Reinforcement layer 4 ... Belt 6 ... Band 8 ... Edge band 10 ... Inner layer 12 ... Outer layer 14 ... Cord of belt 4 16 ... Band 6 18 ... Cord of edge band 8 22 ... Tire 24 ... Tread 26 ... Side wall 30 ... Bead 32 ... Carcass 56 ... First cut ply 58 ... First Two cut plies 60 ... first band 62 ... second band 64 ... end of second cut ply 58 66 ... end of first cut ply 56 68 ... end of first band 60 70 ... End of second band 62 72a, 72b, 72 ... Belt cord 76a, 76b, 76 ... Band cord

Claims (4)

It has a tread, a pair of sidewalls, a pair of beads, a carcass and a reinforcing layer,
Each sidewall extends radially inward from the end of the tread,
Each bead is located radially inward of the sidewall,
The carcass is stretched between one bead and the other bead along the inside of the tread and the sidewall,
The reinforcing layer is laminated with the carcass inside the tread in the radial direction,
The reinforcing layer includes a first cut ply and a second cut ply, and a first band and a second band,
The first cut ply includes a first belt cord extending inclined with respect to the equator plane, and an absolute value of an inclination angle of the first belt cord is 40 ° or more and 70 ° or less;
The second cut ply includes a second belt cord extending inclined with respect to the equator plane, and the inclination direction of the second belt cord is opposite to the inclination direction of the first belt cord, The absolute value of the inclination angle of the second belt cord is equivalent to the absolute value of the inclination angle of the first belt cord,
The first band includes a first band cord extending substantially circumferentially;
The second band includes a second band cord extending substantially circumferentially;
In the radial direction, the first band is located outside the first cut ply, the second cut ply is located outside the first band, and the second band is the second cut ply. Pneumatic tire located on the outside of the. The first band cord and the second band cord are made of organic fibers,
The pneumatic tire according to claim 1, wherein the organic fibers are nylon fibers or aramid fibers.   The position of the end of the second band coincides with the position of the end of the first cut ply in the axial direction, or the end of the second band is axially outer than the end of the first cut ply. The pneumatic tire according to claim 1, which is located in   The pneumatic tire according to claim 3, wherein a distance from an end of the first cut ply to an end of the second band is 10 mm or less.

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