JP6438269B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire.

  Race tires are used in situations where high-speed turning, rapid acceleration and braking are repeated. Race tires are required to have high handling stability in these situations. Moreover, high durability is also required for racing tires because high loads are frequently applied.

  In a racing vehicle, a negative camber is employed to improve turning performance. In this vehicle, when traveling straight, both the left and right tires are located on the inner side of the vehicle when the tire is mounted on the vehicle (in the present specification, this is referred to as the “back side”). The outside of the vehicle is called the “front side”). For this reason, the back side portion of the tread surface repeats deformation and restoration particularly frequently during traveling. During traveling, the stress due to this deformation tends to concentrate on the ends of the belt and the band. This can be a cause of looseness (damage) at the belt end or band end on the back side of the tire.

  In order to suppress the looseness at the belt end, a fold structure in which the axial end is folded back may be used. Japanese Patent Application Laid-Open No. 2012-56473 reports a study on a tire having a fold structure belt. In this tire, an attempt is made to reduce uneven wear of the tire while improving durability and steering stability.

JP 2012-56473 A

  The belt is composed of a large number of cords arranged in parallel and a topping rubber. The fold belt is folded around its end. For this reason, it is difficult to use a metal such as steel as the material of the cord. In this belt, an organic fiber is generally used as a cord material. When an organic fiber is used for the cord, it may happen that the rigidity of the tire cannot be made higher than when a metal is used for the cord. In a tire having a fold structure, there may be a case where the improvement effect of steering stability is not sufficiently improved.

  There is a method of providing an edge band in addition to a band in order to suppress the looseness of the belt without using a fold structure. It is the “end” of the belt or band that is likely to be the starting point of looseness. The edge band has an “end”. In this method, the number of “ends” that are likely to be the origin of looseness is increasing. A tire using this method may be required to further improve the loosening suppression performance.

  An object of the present invention is to provide a tire having excellent durability and excellent steering stability.

  The tire according to the present invention includes a tread whose outer surface forms a tread surface, a belt positioned on the inner side in the radial direction of the tread, and a band that covers the belt on the outer side in the radial direction of the belt. When this tire is mounted on the vehicle, the inner side of the vehicle is the back side, and when the tire is mounted on the vehicle, the outer side of the vehicle is the front side, the tire is cut in a plane perpendicular to the circumferential direction. In the cross section, the band is folded around the back end of the belt. Thereby, the center part and the first edge part are formed in the band. The first edge portion is located between the center portion and the belt.

  Preferably, the axial width of the first edge portion is not less than 10 mm and not more than 30 mm.

  Preferably, in a cross section obtained by cutting the tire along a plane perpendicular to the circumferential direction, the band is folded around the front end of the belt. Thereby, the second edge portion is further formed on the band. The second edge portion is stacked on the radially outer side of the center portion.

  In a cross-section obtained by cutting the tire along a plane perpendicular to the circumferential direction, the band is folded around the front end of the belt, whereby a second edge portion is further formed on the band, and the second An edge portion may be located between the center portion and the belt.

  Preferably, the axial width of the second edge is not less than 50 mm and not more than 80 mm.

  Preferably, the belt includes an inner layer and an outer layer laminated on a radially outer side of the inner layer. The front side end of the first edge portion is located on the front side of the back side end of the outer layer. The axial distance between the front side end of the first edge portion and the back side end of the outer layer is 5 mm or more and 10 mm or less.

  Preferably, the belt includes an inner layer and an outer layer laminated on a radially outer side of the inner layer. Each of the inner layer and the outer layer includes a number of cords arranged in parallel. The cord of the inner layer and the cord of the outer layer are inclined with respect to the equator plane. The inclination direction of the inner layer cord with respect to the equator plane is opposite to the inclination direction of the outer layer cord with respect to the equator plane. The absolute values of the inclination angles of the inner layer cord and the outer layer cord with respect to the equator plane are 30 ° or more and 75 ° or less.

  Preferably, the tire further includes a pair of rubber sheets covering the outer ends in the axial direction of the inner layer and the outer layer.

  Preferably, the axial width WR of each rubber sheet is 20 mm or more and 40 mm or less, and the thickness TR of this rubber sheet is 0.3 mm or more and 0.7 mm or less.

  Preferably, the loss tangent LT of the rubber sheet is 0.20 or less.

  Preferably, when the point on the tread surface, where the axial distance from the equator plane CL is 0.8 times the axial distance from the equator plane CL to the tread end 50, is set to P, the point P The tread thickness TS in is from 2.0 mm to 3.0 mm.

  Preferably, the band includes a cord extending substantially in the circumferential direction. This cord is a hybrid fiber having nylon fibers and aramid fibers.

  In the tire according to the present invention, the band is folded back from the back side to the front side in the vicinity of the back side end of the belt, whereby the center part and the first edge part are formed in the band. The first edge portion is located between the center portion and the belt. The center portion and the first edge portion suppress the occurrence of looseness at the back side end of the belt. In addition, since the first edge portion is located between the center portion and the belt, the occurrence of looseness at the end of the first edge portion is suppressed. This tire is excellent in durability. In this tire, the belt need not have a fold structure. The belt cord material can be metal. This tire is excellent in handling stability.

FIG. 1 is a cross-sectional view showing a part of a tire according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing the structure of the belt of the tire of FIG. FIG. 3 is an enlarged cross-sectional view showing a part of the back side of the tire of FIG. 1. FIG. 4 is an enlarged cross-sectional view showing a part of the front side of the tire of FIG. 1. FIG. 5 is an enlarged cross-sectional view showing a part of the front side of a tire according to another embodiment.

  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 2. In FIG. 1, the vertical direction is the radial direction of the tire 2, the horizontal direction is the axial direction of the tire 2, and the direction perpendicular to the paper surface is the circumferential direction of the tire 2. In the present specification, the inside of the vehicle when the tire 2 is mounted on the vehicle is referred to as the “back side”. On the other hand, the outside of the vehicle is referred to as “front side”. In FIG. 1, arrow X represents the back side, and arrow Y represents the front side. In FIG. 1, an alternate long and short dash line CL represents the equator plane of the tire 2. The shape of the tire 2 is symmetric with respect to the equator plane except for a band described later.

  The tire 2 includes a tread 4, a pair of sidewalls 6, a pair of beads 8, a carcass 10, an inner liner 12, a pair of chafers 14, a belt 16, a band 18, and a pair of rubber sheets 20. The tire 2 is a tubeless type. The tire 2 is attached to a four-wheeled vehicle for racing. The tire 2 may be mounted on a four-wheeled vehicle other than the one for racing.

  The tread 4 has a shape protruding outward in the radial direction. The tread 4 forms a tread surface 22 that contacts the road surface. The tread surface 22 has no groove. The tire 2 is a slick tire 2. A groove may be carved in the tread surface 22. The tread 4 is made of a crosslinked rubber having excellent wear resistance, heat resistance, and grip properties.

  Each sidewall 6 extends substantially inward in the radial direction from the end of the tread 4. The radially outer end of each sidewall 6 is joined to the tread 4. This sidewall 6 is made of a crosslinked rubber having excellent cut resistance and weather resistance. The sidewall 6 prevents the carcass 10 from being damaged.

  Each bead 8 is located inside the sidewall 6 in the axial 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 along the circumferential direction of the tire 2. The core 24 includes a wound non-stretchable wire. A typical material for the wire is steel. The apex 26 is tapered outward in the radial direction. The apex 26 is made of a highly hard crosslinked rubber.

  The carcass 10 includes a first ply 10a and a second ply 10b. The first ply 10 a and the second ply 10 b are bridged between the beads 8 on both sides, and extend along the tread 4 and the sidewall 6. The first ply 10a is folded around the core 24 from the inner side to the outer side in the axial direction. By this folding, a main portion and a folded portion are formed in the first ply 10a. The second ply 10b is folded around the core 24 from the inner side to the outer side in the axial direction. By this folding, a main portion and a folded portion are formed in the second ply 10b.

  Although not shown, the first ply 10a and the second ply 10b are composed of a large number of cords arranged in parallel and a topping rubber. The absolute value of the angle formed by each cord with respect to the equator plane CL is 50 ° to 90 °. In other words, the carcass 10 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 carcass 10 may be formed from a single ply.

  The inner liner 12 is located inside the carcass 10. The inner liner 12 is joined to the inner surface of the carcass 10. The inner liner 12 is made of a crosslinked rubber. The inner liner 12 is made of rubber having excellent air shielding properties. A typical base rubber of the inner liner 12 is butyl rubber or halogenated butyl rubber. The inner liner 12 holds the internal pressure of the tire 2.

  Each chafer 14 is located in the vicinity of the bead 8. When the tire 2 is incorporated into the rim, the chafer 14 comes into contact with the rim. By this contact, the vicinity of the bead 8 is protected. The chafer 14 is made of cloth and rubber impregnated in the cloth.

  The belt 16 is located inside the tread 4 in the radial direction. The belt 16 is laminated with the carcass 10. The belt 16 reinforces the carcass 10. FIG. 2 shows a part of the belt 16. In FIG. 2, the vertical direction is the circumferential direction of the tire 2, the horizontal direction is the axial direction of the tire 2, and the direction perpendicular to the paper surface is the radial direction of the tire 2. In FIG. 2, an alternate long and short dash line CL represents the equator plane of the tire 2. As shown in the figure, the belt 16 includes an inner layer 16a and an outer layer 16b. Each of the inner layer 16a and the outer layer 16b includes a large number of cords 28 and a topping rubber 30 arranged in parallel. Each cord 28 is inclined with respect to the equator plane. As shown in the drawing, the inclination direction of the cord 28 of the inner layer 16a with respect to the equator plane is opposite to the inclination direction of the cord 28 of the outer layer 16b with respect to the equator plane. The difference between the absolute value of the inclination angle of the cord 28 of the inner layer 16a with respect to the equator plane and the absolute value of the inclination angle of the cord 28 of the outer layer 16b with respect to the equator plane CL is within 2 °. That is, these absolute values are the same. In the present specification, this absolute value is expressed as α. The absolute value α of the tilt angle is not less than 30 ° and not more than 75 °. In the tire 2, the material of the cord 28 is steel. An organic fiber may be used for the cord 28. The belt 16 may include three or more layers.

  As will be described later, when the absolute value α is set to 30 ° or more and 75 ° or less, the tire 2 contributes to improvement of high-speed durability. The absolute value α is preferably 30 ° or more and 75 ° or less, but this is not an essential component. The absolute value α may be 15 ° or more and less than 30 °.

  The band 18 is located on the radially outer side of the belt 16. In the axial direction, the width of the band 18 is larger than the width of the belt 16. The band 18 covers the belt 16.

  FIG. 3 is an enlarged cross-sectional view showing the vicinity of the tread 4 end on the back side. As shown in the figure, the band 18 is folded back in the vicinity of the back side end 31 of the belt 16 in a cross section obtained by cutting the tire 2 along a plane perpendicular to the circumferential direction. By this folding, a center portion 32 and a first edge portion 34 are formed on the band 18. The first edge portion 34 is located between the center portion 32 and the belt 16. The front side end 36 of the first edge portion 34 is located on the front side of the back side end 38 of the outer layer 16b. In other words, the first edge portion 34 and the outer layer 16b have overlapping portions in the radial direction.

  FIG. 4 is an enlarged cross-sectional view showing the vicinity of the front tread 4 end. As shown in the figure, the band 18 is folded around the front end 42 of the belt 16 in a cross section of the tire 2 taken along a plane perpendicular to the circumferential direction. By this folding, a second edge portion 40 is further formed on the band 18. The second edge portion 40 is stacked on the outer side in the radial direction of the center portion 32. The shape in which the first edge portion 34 is located on the radially inner side of the center portion 32 and the second edge portion 40 is located on the radially outer side of the center portion 32 in this manner is referred to as “S-shape”. This band 18 is S-shaped.

  Although not shown, the band 18 is composed of a cord and a topping rubber. The cord is wound in a spiral. The band 18 has a so-called jointless structure. The cord extends substantially in the circumferential direction. The angle of the cord with respect to the circumferential direction is 5 ° or less, and further 2 ° or less. Since the end of the belt 16 is restrained by this cord, the lifting of the belt 16 is suppressed. The cord is made of organic fiber. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  Each rubber sheet 20 covers the axially outer end of the belt 16. As shown in FIG. 3, the rubber sheet 20 located on the back side covers the back side end 45 of the inner layer 16a and the back side end 38 of the outer layer 16b. A part of the front side of the rubber sheet 20 is sandwiched between the first edge portion 34 and the belt 16. The end of the back side of the rubber sheet 20 is laminated on the carcass 10. As shown in FIG. 4, the rubber sheet 20 located on the front side covers the front side end 47 of the inner layer 16a and the front side end 49 of the outer layer 16b. A part of the back side of the rubber sheet 20 is sandwiched between the center portion 32 and the belt 16. An end on the front side of the rubber sheet 20 is laminated on the carcass 10.

  As will be described later, the rubber sheet 20 contributes to the improvement of the high speed durability of the tire 2. The tire 2 preferably includes the rubber sheet 20, but the rubber sheet 20 is not an essential component. The tire 2 may not include the rubber sheet 20.

  Hereinafter, the manufacturing method of this tire 2 is shown.

  First, a plurality of cords are extruded together with a topping rubber, and a ribbon for forming the band 18 is obtained. The ribbon is supplied to a former (not shown) together with a sheet for forming the inner liner 12, the carcass 10, the belt 16, and the rubber sheet 20.

  The former includes a cylindrical drum. The drum is rotatable. The inner liner 12, the carcass 10, and the belt 16 are wound around the former in order. A rubber sheet 20 is wound so as to cover the outer end of the belt 16 in the axial direction.

  Next, the ribbon is spirally wound on the outer side in the radial direction of the belt 16. The ribbon starts to be wound outside the belt 16 from a position to be the front end 36 of the first edge portion 34. The ribbon is spirally wound in a substantially circumferential direction from this position toward a position to become the back side end 44 of the first edge portion 34. Thereby, the 1st edge part 34 is formed. Subsequently, the ribbon spirals in a substantially circumferential direction from the outer side in the radial direction of the back side end 44 of the first edge part 34 (the position to be the back side end of the center part 32) to the position to be the front side end of the center part 32. Wrapped around. Thereby, the center part 32 is formed. Subsequently, the ribbon is substantially circumferentially directed from the radially outer side of the front end of the center portion 32 (the position to be the front end 46 of the second edge portion 40) to the position to be the back end 48 of the second edge portion 40. Wound spirally in the direction. Thereby, the second edge portion 40 is formed. Thus, the S-shaped band 18 is formed.

  As described above, the band 18 is formed from a single ribbon. In other words, in the band 18, the end of the ribbon is a front side end 36 of the first edge portion 34 that is the starting point of winding and a back side end 48 of the second edge portion 40 that is the end point of winding. There are two places.

  After the band 18 is formed, the tread 4 is further combined with the outside of the band 18. As a result, a low cover (also referred to as an uncrosslinked tire) is obtained.

  The raw cover is put into a mold (not shown). As a result, the outer surface of the raw cover comes into 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 2 is obtained.

  Hereinafter, the effect by this invention is demonstrated.

  In a vehicle in which a negative camber is adopted, when traveling straight, both the left and right tires are grounded on the back side of the tread surface. For this reason, the back side portion of the tread surface repeats deformation and restoration particularly frequently during traveling. For this reason, looseness tends to occur at the back side end of the belt and the back side end of the band. A fold belt may be used to suppress looseness. However, since this belt is folded in the vicinity of its end, it is difficult to use a metal such as steel as the material of the cord. When metal is not used for the cord, it may happen that the rigidity of the tire cannot be increased as compared with the case where metal is used for the cord. In a tire having a fold structure, there may be a case where the effect of improving the steering stability cannot be sufficiently improved.

  In the tire 2 according to the present invention, the band 18 is folded around the back end 31 of the belt 16. As a result, a center portion 32 and a first edge portion 34 are formed in the band 18. The center portion 32 and the first edge portion 34 protect the vicinity of the back side end 45 of the inner layer 16a and the back side end 38 of the outer layer 16b, which are likely to be loose. Rubber deformation at the back side end 45 of the inner layer 16a and the back side end 38 of the outer layer 16b is reduced. This suppresses the occurrence of looseness starting from the back side end 45 of the inner layer 16a and the back side end 38 of the outer layer 16b. The tire 2 is excellent in durability.

  In the tire 2, the first edge portion 34 is located between the center portion 32 and the belt 16. A front side end 36 of the first edge portion 34 is located between the center portion 32 and the belt 16. This structure suppresses the occurrence of looseness starting from the end of the first edge portion 34. In the tire 2, the occurrence of looseness on the back side of the tire 2 is suppressed.

  As described above, the structure of the band 18 suppresses the occurrence of looseness starting from the back side end 31 of the belt 16. In the tire 2, the belt 16 does not need to have a fold structure. Metal can be used as the material of the cord 28 of the belt 16. The tire 2 can have sufficient rigidity. The tire 2 is excellent in handling stability.

  In FIG. 3, a double-headed arrow W <b> 1 is the axial width of the first edge portion 34. The width W1 is preferably 10 mm or more. By setting the width W1 to 10 mm or more, the first edge portion 34 effectively suppresses the occurrence of looseness at the back side end 31 of the belt 16. In this respect, the width W1 is more preferably equal to or greater than 15 mm. The width W1 is preferably 30 mm or less. By setting the width W1 to 30 mm or less, the rigidity on the back side of the tread 4 can be appropriately maintained. Excessive rigidity on the back side of the tread 4 is suppressed. The tire 2 is excellent in handling stability. In this respect, the width W1 is more preferably equal to or less than 25 mm.

  In FIG. 3, a double-headed arrow S is an axial distance between the front side end 36 of the first edge portion 34 and the back side end 38 of the outer layer 16b. The interval S is preferably 5 mm or more. By setting the interval S to 5 mm or more, the front side end 36 of the first edge portion 34 and the back side end 38 of the outer layer 16b have a sufficient distance. Distortion concentration due to the proximity of the front side end 36 of the first edge portion 34 and the back side end 38 of the outer layer 16b is suppressed. This suppresses the occurrence of looseness starting from the front side end 36 of the first edge portion 34 and the back side end 38 of the outer layer 16b. The tire 2 is excellent in durability. In this respect, the interval S is preferably 6 mm or more. The interval S is preferably 10 mm or less. By setting the interval S to 10 mm or less, the rigidity on the back side of the tread 4 can be appropriately maintained. Excessive rigidity on the back side of the tread 4 is suppressed. The tire 2 is excellent in handling stability. From this viewpoint, the interval S is more preferably 9 mm or less.

  When the vehicle turns, a lateral force is applied to the front side of the outer ring. In the racing tire 2 that often turns at high speed, a particularly large lateral force is applied to the front side of the tire 2. Due to the lateral force, “buckling” that deforms so that the front side of the tread 4 undulates may occur. When buckling occurs, the contact area of the tire 2 decreases. The force transmitted from the tire 2 to the road surface is reduced. This impairs the steering stability of the tire 2. This leads to a decrease in the wear resistance performance of the tire 2.

  In the tire 2 according to the present invention, the band 18 is folded around the front end 42 of the belt 16. As a result, a second edge portion 40 is further formed on the band 18. The second edge portion 40 contributes to the improvement of the rigidity on the front side of the tire 2. The second edge portion 40 suppresses buckling on the front side of the tread 4. In the tire 2, the occurrence of buckling is suppressed. The tire 2 has good steering stability and wear resistance.

  As described above, the second edge portion 40 is stacked on the radially outer side of the center portion 32. This band 18 is S-shaped. The band 18 which is S-shaped can be formed from a single ribbon. In this band 18, the ribbon ends at only two places: the front side end 36 of the first edge portion 34 that is the starting point of winding and the back side end 48 of the second edge portion 40 that is the end point of winding. is there. This can suppress the occurrence of looseness starting from the end of the ribbon. In this band 18, the occurrence of loose is suppressed. Further, in the tire 2, the end of the ribbon is not located in the vicinity of the crown portion of the tire 2. This contributes to the realization of good uniformity. The tire 2 is excellent in uniformity.

  In FIG. 4, the double-headed arrow W <b> 2 is the axial width of the second edge portion 40. The width W2 is preferably 50 mm or more. The second edge portion 40 effectively suppresses the occurrence of buckling by setting the width W2 to 50 mm or more. The tire 2 has good steering stability and wear resistance. In this respect, the width W2 is more preferably equal to or greater than 55 mm. The width W2 is preferably 80 mm or less. By setting the width W2 to 80 mm or less, the rigidity on the front side of the tread 4 can be properly maintained. Excessive rigidity on the front side of the tread 4 is suppressed. The tire 2 is excellent in handling stability. In this respect, the width W2 is more preferably equal to or less than 75 mm.

  Due to the strong ground pressure, the tread surface 22 of the tire 2 is loaded with a force from the shoulder portion toward the equator plane CL. This force causes the tread 4 to be deformed in the direction of the equator plane CL on the ground contact surface. When this part moves away from the road surface, a force called a wiping force works by restoring this deformation. The wiping force can cause a slip on the road surface of the tire 2. The wiping force causes a decrease in the grip performance of the tire 2.

  As described above, the absolute value α of the inclination angle of the cord 28 of the belt 16 with respect to the equator plane CL is preferably 30 ° or more. By setting the absolute value α to 30 ° or more, the belt 16 has good rigidity with respect to a lateral force. The belt 16 contributes to a reduction in wiping force. Further, the belt 16 contributes to suppression of buckling. The tire 2 is excellent in grip power. The tire 2 has good steering stability and wear resistance. The absolute value α is preferably 75 ° or less. By setting the absolute value α to 75 ° or less, deformation at the shoulder portion of the tread 4 due to centrifugal force during high-speed traveling is suppressed. This suppresses heat generation at the shoulder. In the tire 2, separation between the belt 16 and the band 18 due to deformation of the shoulder portion and heat generation is suppressed. The tire 2 maintains good high-speed durability.

  As described above, it is preferable to provide the rubber sheet 20 that covers the outer end of the belt 16 in the axial direction. The rubber sheet 20 relieves stress between the belt 16 and the band 18 when deformation at the shoulder portion occurs due to centrifugal force during high-speed traveling. The rubber sheet 20 effectively contributes to suppression of separation between the belt 16 and the band 18 at the shoulder portion. Further, the rubber sheet 20 suppresses heat generation due to deformation at the shoulder portion during high speed traveling. The tire 2 is excellent in high speed durability.

  3 and 4, the double arrow TR is the thickness of the rubber sheet 20. The thickness TR is preferably 0.3 mm or more. By setting the thickness TR to 0.3 mm or more, the rubber sheet 20 effectively contributes to suppression of separation between the belt 16 and the band 18. The rubber sheet 20 effectively suppresses heat generation due to deformation at the shoulder portion during high speed running. The tire 2 is excellent in high speed durability. The thickness TR is preferably 0.7 mm or less. By setting the thickness TR to 0.7 mm or less, the rigidity in the shoulder portion is appropriately maintained. The tire 2 is excellent in handling stability. From the viewpoint of achieving both high-speed durability and steering stability effectively, the thickness TR is more preferably 0.5 mm.

  3 and 4, the double-headed arrow WR is the axial width of the rubber sheet 20. The width WR is preferably 20 mm or more. By setting the width WR to 20 mm or more, the rubber sheet 20 effectively contributes to suppression of separation between the belt 16 and the band 18. The rubber sheet 20 effectively suppresses heat generation due to deformation at the shoulder portion during high speed running. The tire 2 is excellent in high speed durability. The width WR is preferably 40 mm or less. By setting the width WR to 40 mm or less, the rigidity in the shoulder portion is appropriately maintained. The tire 2 is excellent in handling stability. From the viewpoint of achieving both high-speed durability and steering stability effectively, the width WR is more preferably 30 mm.

  The loss tangent LT of the rubber sheet 20 is preferably 0.2 or less. By setting the loss tangent LT to 0.2 or less, the rubber sheet 20 effectively suppresses heat generation due to deformation at the shoulder portion during high-speed traveling. The tire 2 is excellent in high speed durability. The loss tangent LT is preferably 0.05 or more.

In the present invention, the loss tangent LT of the rubber sheet 20 is a viscoelastic spectrometer (trade name “VESF-3” manufactured by Iwamoto Seisakusho Co., Ltd.) according to the following measurement conditions in accordance with the provisions of “JIS K 6394”. It is measured using. In this measurement, a plate-shaped test piece (length = 45 mm, width = 4 mm, thickness = 2 mm) is formed from the rubber composition of the rubber sheet 20. This test piece is used for measurement.
Initial strain: 10%
Amplitude: ± 2.0%
Frequency: 10Hz
Deformation mode: Tensile
Measurement temperature: 70 ° C

  In FIG. 1, a double arrow WT represents an axial width from the equator plane CL to the tread end 50. Point P is a point on the tread surface 22 and is a point where the axial distance WP from the equator plane CL is 0.8 times the width WT. That is, the point P is a point on the tread surface 22 where the ratio (WP / WT) of the distance WP to the width WT is 0.8. In the tire 2, the thickness of the shoulder portion means the thickness of the tread 4 measured at the point P. In the figure, the double arrow TS is the thickness of the shoulder portion. Specifically, the thickness TS of the shoulder portion is the distance between the outer surface and the inner surface of the tread 4 measured along the normal line V drawn from the point P. The thickness TS is preferably 3.0 mm or less. By setting the thickness TS to 3.0 mm or less, heat generation due to deformation at the shoulder portion is effectively suppressed. The tire 2 is excellent in high speed durability. The thickness TS is preferably 2.0 mm or more. By setting the thickness TS to 2.0 mm or more, good wear resistance is maintained in this shoulder portion.

  As described above, the preferable range of the thickness TS has been described in the figure on the back side of the tire 2. This preferable range is the same also on the front side of the tire 2. Also on the front side of the tire 2, the thickness TS is preferably 2.0 mm or greater and 3.0 mm or less.

  In the tire 2, the cord 18 of the band 18 is preferably a hybrid fiber having an aramid fiber and a nylon fiber. The cord material of the band 18 is preferably a hybrid fiber made of an aramid fiber and a nylon fiber. In this cord, an aramid fiber and a nylon fiber are twisted together. The hybrid fiber having an aramid fiber and a nylon fiber is excellent in adhesiveness with the rubber composition. By using this hybrid fiber as the cord material, the separation of the rubber from the cord in the band 18 is effectively suppressed. In the tire 2, separation due to deformation at the shoulder portion during high-speed traveling is effectively suppressed. Furthermore, aramid fiber and nylon fiber are excellent in durability. The tire 2 is excellent in high speed durability.

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

  FIG. 5 shows a pneumatic tire 52 according to another embodiment of the present invention. This figure is an enlarged cross-sectional view showing the vicinity of the tread end on the front side. In FIG. 5, the vertical direction is the radial direction of the tire 52, the horizontal direction is the axial direction of the tire 52, and the direction perpendicular to the paper surface is the circumferential direction of the tire 52.

  The tire 52 includes a tread 54, a pair of sidewalls, a pair of beads, a carcass 56, an inner liner 58, a pair of chafers, a belt 60, a band 62, and a pair of rubber sheets 64. The tire 52 has the same structure as the tire 2 of FIG.

  The band 62 is located on the radially outer side of the belt 60. In the axial direction, the width of the band 62 is larger than the width of the belt 60. The band 62 covers the belt 60. The back side of the band 62 of the tire 52 has the same structure as the band 18 of the tire 2 in FIG.

  As shown in FIG. 5, the band 62 is folded in the vicinity of the front end 66 of the belt 60 in a cross section obtained by cutting the tire 52 along a plane perpendicular to the circumferential direction. By this folding, a center portion 68 and a second edge portion 70 are formed on the band 62. The second edge portion 70 is located between the center portion 68 and the belt 60. The back side end 72 of the second edge portion 70 is located on the back side of the front side end 74 of the outer layer 60 b of the belt 60. In other words, the second edge portion 70 and the outer layer 60b have overlapping portions in the radial direction. The shape in which the first edge portion and the second edge portion 70 are located on the radially inner side of the center portion 68 in this manner is referred to as “C-shape”. This band 62 is C-shaped.

  Hereinafter, a method for manufacturing the tire 52 will be described.

  First, a plurality of cords are extruded together with a topping rubber, and a first ribbon and a second ribbon for forming the band 62 are obtained. The first ribbon and the second ribbon are supplied to a former (not shown) together with sheets for forming the inner liner 58, the carcass 56, the belt 60, and the rubber sheet 64.

  The former includes a cylindrical drum. The drum is rotatable. The inner liner 58, the carcass 56, and the belt 60 are wound around the former in order. A rubber sheet 64 is wound so as to cover the outer end of the belt 60 in the axial direction.

  Next, the first ribbon and the second ribbon are spirally wound outside the belt 60 in the radial direction. The first ribbon starts to be wound outside the belt 60 from a position to be the front side end of the first edge portion. The first ribbon is spirally wound in a substantially circumferential direction from this position toward a position to be the back side end of the first edge portion. Thereby, the first edge portion is formed. Subsequently, the first ribbon is spirally wound in a substantially circumferential direction toward the equatorial plane CL from the outside in the radial direction of the back side end of the first edge portion (position to be the back side end of the center portion 68). Thereby, the back side of the center part 68 is formed.

  In parallel with the winding of the first ribbon, the second ribbon is also wound. The second ribbon starts to be wound outside the belt 60 from a position where it should become the back side end 72 of the second edge portion 70. The second ribbon is spirally wound in a substantially circumferential direction from this position toward a position to become the front side end 76 of the second edge portion 70. Thereby, the 2nd edge part 70 is formed. Subsequently, the second ribbon is spirally wound in a substantially circumferential direction toward the equatorial plane CL from the outside in the radial direction of the front side end 76 of the second edge portion 70 (position to be the front side end of the center portion 68). Thereby, the front side of the center part 68 is formed. As described above, the C-shaped band 62 is formed.

  As described above, the band 62 is formed from two ribbons. In other words, in the band 62, the ribbon end is the front side end of the first edge portion which is the starting point of the first ribbon winding, and the equator plane of the center portion 68 which is the end point of the first ribbon winding. CL, four points on the back side end 72 of the second edge portion 70 that is the starting point of winding of the second ribbon, and the equatorial plane CL of the center portion 68 that is the end point of winding of the second ribbon.

  After the band 62 is formed, the tread 54 is further combined with the outside of the band 62. Thereby, a raw cover is obtained.

  The raw cover is put into a mold (not shown). As a result, the outer surface of the raw cover comes into 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 52 is obtained.

  Hereinafter, the effect by this invention is demonstrated.

  In the tire 52 according to the present invention, the band 62 is folded back in the vicinity of the back side end of the belt 60, whereby a center portion 68 and a first edge portion are formed on the band 62. The center portion 68 and the first edge portion protect the vicinity of the back side ends of the inner layer 60a and the outer layer 60b where looseness is likely to occur. Rubber deformation at the back side end of the inner layer 60a and the back side end of the outer layer 60b is reduced. This suppresses the occurrence of loose starting from the back side end of the inner layer 60a and the back side end of the outer layer 60b. The tire 52 is excellent in durability.

  In the tire 52, the first edge portion is located between the center portion 68 and the belt 60. The end of the first edge portion is located between the center portion 68 and the belt 60. This structure suppresses the occurrence of loose starting from the front side end of the first edge portion. In the tire 52, the occurrence of looseness at the back side end of the band 62 is suppressed.

  As described above, the structure of the band 62 suppresses the occurrence of looseness starting from the back side end of the belt 60. In the tire 52, the belt 60 does not need to have a fold structure. A metal can be used as the material of the cord of the belt 60. The tire 52 is excellent in handling stability.

  In the tire 52, the band 62 is folded around the front end 66 of the belt 60. As a result, the second edge portion 70 is formed on the band 62. The second edge portion 70 contributes to improving the rigidity on the front side of the tire 52. The second edge portion 70 suppresses buckling on the front side of the tread 54. In the tire 52, occurrence of buckling is suppressed. The tire 52 has good steering stability and wear resistance.

  In the tire 52, the second edge portion 70 is located between the center portion 68 and the belt 60. The back side end 72 of the second edge portion 70 is located between the center portion 68 and the belt 60. This structure suppresses the generation of loose starting from the back side end 72 of the second edge portion 70. In the tire 52, the occurrence of looseness on the front side is suppressed.

  In FIG. 5, a double arrow W <b> 2 is the axial width of the second edge portion 70. The width W2 is preferably 50 mm or more. By setting the width W2 to 50 mm or more, the second edge effectively suppresses the occurrence of buckling. The tire 52 has good steering stability and wear resistance. In this respect, the width W2 is more preferably equal to or greater than 55 mm. The width W2 is preferably 80 mm or less. By setting the width W2 to 80 mm or less, the rigidity on the front side of the tread 54 can be appropriately maintained. Excessive rigidity on the front side of the tread 54 is suppressed. The tire 52 is excellent in handling stability. In this respect, the width W2 is more preferably equal to or less than 75 mm.

  Although not shown, there is a tire including a band whose front side is not folded as still another embodiment of the present invention. The back side of this band has the same structure as the tire 2 of FIG. In other words, this band has a first edge portion and does not have a second edge portion. Such a shape is referred to as a “J-shape”. This J-shaped band suppresses the occurrence of looseness starting from the back side end of the inner layer of the belt and the back side end of the outer layer. In this band, the occurrence of loose starting from the front side end of the first edge portion is suppressed. In this tire, the occurrence of looseness at the back side end of the band is suppressed. This tire is excellent in durability. Further, with this tire, the belt need not have a fold structure. The belt cord material can be metal. This tire is excellent in handling stability.

  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.

[Experiment 1]
[Example 1]
A tire of Example 1 having the configuration shown in FIG. 1 was obtained except that no rubber sheet was provided. The tire size was 265 / 35R18. Table 1 shows the specifications of the tire. This band is S-shaped. This is represented as "S" in the band shape column. The absolute value α of the inclination angle of the belt cord with respect to the equator plane CL is 30 °. The band cord material is aramid fiber. In this tire, the thickness TS is 0.3 mm.

[Comparative Example 1]
A tire of Comparative Example 1 was obtained in the same manner as in Example 1 except that the band structure was composed of a single full band and a pair of single edge bands. The fact that the band is composed of one full band and a pair of one edge band is represented as “1FB + 1EB” in the band shape column. This is a conventional tire.

[Example 2]
A tire of Example 2 was obtained in the same manner as Example 1 except that the band was C-shaped.

[Comparative Example 2]
A tire of Comparative Example 2 was obtained in the same manner as in Example 1 except that the band was inverted S-shaped. Here, the inverted S shape means a structure in which the first edge portion is located radially outside the center portion and the second edge portion is located radially inside the center portion. The fact that the band is inverted S-shaped is represented as “inverted S-shaped” in the band shape column.

[Example 3-6]
A tire of Example 3-6 was obtained in the same manner as in Example 1 except that the structure of the band was changed and the width W1 and the interval S were changed as shown in Table 2.

[Example 7-10]
Tires of Examples 7-10 were obtained in the same manner as Example 1 except that the width W2 was as shown in Table 3.

[Examples 11-14]
Tires of Examples 11-14 were obtained in the same manner as Example 1 except that the band structure was changed and the interval S was changed as shown in Table 4.

[lap time]
A prototype tire was incorporated into a standard rim (size = 18 × 9.5 J), and the tire was filled with air to adjust the internal pressure to 180 kPa. This tire was mounted on the rear wheel of a rear-driven automobile having a displacement of 2600 cc. A commercially available tire (size: 265 / 35R18) was attached to the front wheel and filled with air so that the internal pressure was 180 kPa. The car was driven on a circuit course with asphalt on the road surface. The lap time was measured by running 10 laps on a 4.5 km course. The reciprocal of the average value of the measurement results is shown in Tables 1 to 4 below as an index with the value of Comparative Example 1 being 100. Larger values are preferred.

[Steering stability]
The car was run under the same conditions as the above lap time, and the sensory evaluation was performed by the driver on the handling stability. The results are shown in the following Tables 1 to 4 as indices with the result of Comparative Example 1 as 100. Larger values are preferred.

[Loose length]
The prototype tire was incorporated into a regular rim (size = 18 × 9.5 J), and the tire was filled with air to adjust the internal pressure to 120 kPa. This tire was mounted on a drum-type running test machine, and a vertical load of 7.0 kN was applied to the tire. The slip angle was set to 1.5 °. The camber angle was set to 2.8 °. This tire was run on a drum having a radius of 1.7 m for 60 minutes at a speed of 200 km / h. The cross section of the tire was photographed with an X-ray inspection apparatus, and the length of the looseness generated at the end of the belt and the end of the band was visually measured. The longest loose lengths are shown in Tables 1 to 4 below. The smaller the value, the better.

[Abrasion resistance]
A prototype tire was incorporated into a standard rim (size = 18 × 9.5 J), and the tire was filled with air to adjust the internal pressure to 180 kPa. This tire was mounted on the rear wheel of a rear-driven automobile having a displacement of 2600 cc. A commercially available tire (size: 265 / 35R18) was attached to the front wheel and filled with air so that the internal pressure was 180 kPa. The car was driven 150 km on a circuit course with asphalt on the road surface. The tire was disassembled and the amount of wear of the tread 54 was measured. The reciprocal of the amount of wear is shown in Tables 1 to 4 below as an index with the result of Comparative Example 1 taken as 100. Larger values are preferred.

[Experiment 2]
[Example 15]
A tire of Example 15 having the configuration shown in FIG. 1 was obtained except that no rubber sheet was provided. The tire size was 280 / 680R18. Table 5 shows the specifications of the tire. This band is S-shaped. This is represented as "S" in the band shape column. In this tire, the width W1 was 20 mm, the width W2 was 60 mm, and the interval S was 7 mm. The band cord material is aramid fiber. This is represented as “alamide” in the band material column. In this tire, the thickness TS is 0.3 mm.

[Comparative Example 3]
Comparative Example 3 is the same as Example 15 except that the band structure is composed of one full band and the absolute value α of the inclination angle of the belt cord with respect to the equator plane CL is as shown in Table 5. Tires. The fact that the band is composed of one full band is represented as “1FB” in the band shape column. This is a conventional tire.

[Examples 16-19]
Tires of Examples 16-19 were obtained in the same manner as Example 15 except that the absolute value α was set as shown in Table 5.

[Examples 20-23]
Tires of Examples 20-23 were obtained in the same manner as Example 15 except that a rubber sheet having a thickness TR as shown in Table 6 was provided. The rubber sheet has a width WR of 30 mm.

[Example 24]
A tire of Example 24 was obtained in the same manner as Example 15 except that the material of the band cord was a hybrid fiber composed of aramid fiber and nylon fiber. The material of the cord of the band is a hybrid fiber, which is represented as “hybrid” in the band material column.

[Example 25]
Implementation was performed in the same manner as in Example 15 except that the material of the band cord was a hybrid fiber composed of aramid fiber and nylon fiber and had a rubber sheet having a thickness TR as shown in Table 6 The tire of Example 25 was obtained.

[grip]
A prototype tire was incorporated into a standard rim (size = 18 × 9.5 J), and the tire was filled with air to adjust the internal pressure to 200 kPa. This tire was mounted on the rear wheel of a rear-driven automobile having a displacement of 3000 cc. A commercially available tire (size: 280 / 680R18) was attached to the front wheel and filled with air so that its internal pressure was 200 kPa. The car was run on a circuit course with asphalt on the road surface, and the sensory evaluation of the grip force was performed by the driver. The results are shown in Tables 5 and 6 below as indices with the result of Comparative Example 3 as 100. Larger values are preferred.

[High-speed durability]
The tire was assembled in a rim (size = 18 × 9.5 J), and the tire was filled with air to adjust the internal pressure to 200 kPa. This tire was mounted on a drum-type running test machine, and a longitudinal load of 6 kN was applied to the tire. The slip angle was 1.5 °. The camber angle was 2.8 °. This tire was run on a drum having a diameter of 1.7 m. The evaluation was performed based on the speed at which the tire broke down by gradually increasing the speed. The results are shown in Tables 5 and 6 below, with an index based on Comparative Example 3 being 100. The larger the value, the better the high-speed durability.

  As shown in Tables 1 to 6, the tires of the examples have higher evaluation than the tires of the comparative examples. From this evaluation result, the superiority of the present invention is clear.

  The tire according to the present invention can be applied to a racing vehicle.

2 ... Tire 4, 54 ... Tread 6 ... Sidewall 8 ... Bead 10, 56 ... Carcass 10a ... First ply 10b ... Second ply 12, 58 ... Inner liner 14 ... Chafer 16, 60 ... Belt 16a, 60a ... Inner layer 16b, 60b ... Outer layer 18, 62 ... Band 20, 64 ... Rubber sheet 22 ... Tread surface 24 ... Core 26 ... Apex 28 ... Cord 30 ... Topping rubber 31 ... Back side end 32, 68 ... Center part 34 ... First edge part 36. .... Front side end of first edge part 38 ... Back side end of outer layer 40, 70 ... Second edge part 42, 66 ... Front side end of belt 44 ... Back side end of first edge part 45 ... Back side of inner layer 46, 76 ... front end of the second edge 47 ... front side end of the inner layer 48, 72 ... back side end of the second edge part 49, 74 ... front side end of the outer layer 50 ... Tread edge

Claims (11)

It has a tread whose outer surface forms a tread surface, a belt located on the inner side in the radial direction of the tread, and a band that covers the belt on the outer side in the radial direction of the belt,
When the inside of the vehicle when this tire is attached to the vehicle is the back side, and when the outside of the vehicle when this tire is attached to the vehicle is the front side,
In the cross section of the tire cut by a plane perpendicular to the circumferential direction, the band is folded back near the back side end of the belt, thereby forming a center portion and a first edge portion on the band,
The first edge portion is located between the center portion and the belt ;
In the cross section of the tire cut in a plane perpendicular to the circumferential direction, the band is folded back near the front side end of the belt, thereby further forming a second edge portion on the band,
A pneumatic tire in which the second edge portion is laminated on the radially outer side of the center portion . It has a tread whose outer surface forms a tread surface, a belt located on the inner side in the radial direction of the tread, and a band that covers the belt on the outer side in the radial direction of the belt,
When the inside of the vehicle when this tire is attached to the vehicle is the back side, and when the outside of the vehicle when this tire is attached to the vehicle is the front side,
In the cross section of the tire cut by a plane perpendicular to the circumferential direction, the band is folded back near the back side end of the belt, thereby forming a center portion and a first edge portion on the band,
The first edge portion is located between the center portion and the belt;
The belt includes an inner layer and an outer layer laminated on the outer side in the radial direction of the inner layer, the front side end of the first edge portion is located on the front side of the back side end of the outer layer,
Air-filled tire axial distance Ru der least 10mm or less 5mm and rear end of the front end and the outer layer of said first edge portion. It has a tread whose outer surface forms a tread surface, a belt located on the inner side in the radial direction of the tread, and a band that covers the belt on the outer side in the radial direction of the belt,
When the inside of the vehicle when this tire is attached to the vehicle is the back side, and when the outside of the vehicle when this tire is attached to the vehicle is the front side,
In the cross section of the tire cut by a plane perpendicular to the circumferential direction, the band is folded back near the back side end of the belt, thereby forming a center portion and a first edge portion on the band,
The first edge portion is located between the center portion and the belt;
The belt comprises an inner layer and an outer layer laminated radially outward of the inner layer;
Each of the inner layer and the outer layer comprises a number of cords arranged in parallel,
The cord of the inner layer and the cord of the outer layer are inclined with respect to the equator plane CL,
The inclination direction of the inner layer cord with respect to the equator plane CL is opposite to the inclination direction of the outer layer cord with respect to the equator plane CL,
Absolute value, der Ru pneumatic tire 30 ° or 75 ° or less angle of inclination with respect to the equatorial plane CL of the code in the code and the outer layer of the inner layer. The pneumatic tire according to claim 3 , further comprising a pair of rubber sheets that cover axially outer ends of the inner layer and the outer layer. The pneumatic tire according to claim 4 , wherein an axial width WR of each rubber sheet is 20 mm or more and 40 mm or less, and a thickness TR of the rubber sheet is 0.3 mm or more and 0.7 mm or less. The pneumatic tire according to claim 4 or 5 , wherein the loss tangent LT of the rubber sheet is 0.2 or less. In the cross section obtained by cutting the tire along a surface perpendicular to the circumferential direction, the band is folded back near the front end of the belt, whereby a second edge portion is further formed on the band.
The pneumatic tire according to claim 2 , wherein the second edge portion is located between the center portion and the belt. The pneumatic tire according to any one of claims 1 to 7, wherein an axial width of the first edge portion is not less than 10 mm and not more than 30 mm. In the cross section of the tire cut in a plane perpendicular to the circumferential direction, the band is folded back near the front end of the belt, whereby a second edge portion is further formed on the band,
The pneumatic tire according to any one of claims 1 to 8, wherein an axial width of the second edge is 50 mm or more and 80 mm or less. When a point on the tread surface where the axial distance from the equator plane CL is 0.8 times the axial distance from the equator plane CL to the tread edge 50 is P, the tread at the point P The pneumatic tire according to any one of claims 1 to 9 , wherein the thickness TS is 2.0 mm or more and 3.0 mm or less. The band includes a cord extending substantially in a circumferential direction;
The pneumatic tire according to any one of claims 1 to 10 , wherein the cord is a hybrid fiber having a nylon fiber and an aramid fiber.

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