JP6249525B2 - Pneumatic tire for motorcycles - Google Patents

Description

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

  There is a pneumatic tire with a band in which a cord is spirally wound substantially along a circumferential direction. Such a band is called a jointless band (JLB). This tire is excellent in handling stability and ride comfort in straight running. On the other hand, this tire tends to be inferior in rigidity. The motorcycle is tilted when turning. With this tire, it is difficult to obtain a sufficient camber thrust when the vehicle body is tilted and turns. This tire is inferior in turning performance.

  There is a tire including a reinforcing layer in which a belt ply in which a belt cord is inclined in a circumferential direction is stacked in a plurality of layers. This tire has high rigidity. This tire is excellent in turning performance. On the other hand, this tire tends to be inferior in handling stability and riding comfort in straight running. In this way, it is not easy to achieve both steering stability and riding comfort and turning performance.

  Patent Document 1 proposes a tire in which a band spirally wound in the circumferential direction is coarsely wound. In this tire, the rigidity changes in the axial direction. Patent Document 2 proposes a tire including a band spirally wound in the circumferential direction and a reinforcing belt positioned on the shoulder of the tread. In this tire, the rigidity of the tread shoulder is increased by providing the reinforcing belt.

JP-A-9-118109 JP 2010-285107 A

  In the tire of Patent Document 1, it is necessary to further include another reinforcing layer in order to improve turning performance. Further, the tire of Patent Document 2 further includes a reinforcement belt in the jointless band. These tires are difficult to obtain sufficient rigidity with a jointless band alone.

  An object of the present invention is to provide a tire for a two-wheeled vehicle that achieves both the steering stability in straight traveling and the riding comfort and turning performance.

The two-wheeled vehicle tire according to the present invention has a tread whose outer surface forms a tread surface, a pair of sidewalls each extending substantially inward in the radial direction from the end of the tread, and each positioned radially inward of the sidewalls. A pair of beads, a carcass spanned between one bead and the other bead along the inside of the tread and the sidewall, and a band laminated with the carcass on the radially inner side of the tread are provided.
This band consists of a jointless belt. This belt is composed of a band cord and a topping rubber. The belt body includes a plurality of first main parts wound at an angle with respect to the circumferential direction, and a plurality of second main parts wound at an angle opposite to the first main part with respect to the circumferential direction. It has. The plurality of first main portions and the plurality of second main portions intersect with each other to form a net.

  Preferably, the absolute value of the inclination angle θ1 of the band cord of the first main portion and the inclination angle θ2 of the band cord of the second main portion is 1 ° or more and 10 ° or less.

  Preferably, the absolute value of the inclination angle θ1 of the band cord of the first main portion and the absolute value of the inclination angle θ2 of the band cord of the second main portion are the same.

  The end which is the number of band cords driven per 5 cm width of the band is defined as E1 (lines / 5 cm). An end when the band is wound substantially in the circumferential direction and without any gap in the axial direction and without overlapping in the radial direction is defined as E (line / 5 cm). At this time, preferably, the end E1 of this band is 0.5 to 0.7 times that of the end E.

  Preferably, the band has an end. This end is located at the axial end of the band. This end extends in the circumferential direction. The end portion is located between the first main portion and the second main portion. The end portion is continuous with the first main portion and the second main portion.

  Preferably, the band cord is made of a steel cord.

  In the tire according to the present invention, the band is a jointless belt. Since the band is formed in a net shape to form a band, it is excellent in handling stability, riding comfort and turning performance in straight running. Further, compared to a conventional jointless band in which the cord is spirally wound in the circumferential direction, the same or higher rigidity can be exhibited with a small number of cord windings.

FIG. 1 is a cross-sectional view showing a part of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is an explanatory view showing a part of a strip used in the tire of FIG. 1. FIG. 3 is an explanatory view showing a part of the carcass and the band of the tire of FIG. 1. FIG. 4 is a graph showing the relationship between the inclination angles θ1 and θ2 of the tire cord of FIG. 1 and the cornering power value CP.

  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 FIG. 1, an alternate long and short dash line CL represents the equator plane of the tire. The shape of the tire 2 is symmetrical with respect to the equator plane except for the tread pattern.

  The tire 2 includes a tread 4, a sidewall 6, a bead 8, a carcass 10, a band 12, an inner liner 14, and a chafer 16. The tire 2 is a tubeless type. The tire 2 is attached to a motorcycle.

  The tread 4 has a shape protruding outward in the radial direction. The tread 4 forms a tread surface 18 that contacts the road surface. Although not shown, the tread 4 has a groove. A tread pattern is formed by this groove. The tread 4 has a base layer 20 and a cap layer 22. The cap layer 22 is located on the radially outer side of the base layer 20. The cap layer 22 is laminated on the base layer 20. The base layer 20 is made of a crosslinked rubber having excellent adhesiveness. A typical base rubber of the base layer 20 is natural rubber. The cap layer 22 is made of a crosslinked rubber having excellent wear resistance, heat resistance, and grip properties.

  The sidewall 6 extends substantially inward in the radial direction from the end of the tread 4. A radially outer end of the 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.

  The bead 8 is located inside the sidewall 6 in the radial direction. The bead 8 includes a core 24 and an apex 26 that extends radially outward from the core 24. The core 24 has a ring shape and 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 28 and a second ply 30. The first ply 28 and the second ply 30 are bridged between the beads 8 on both sides, and extend along the tread 4 and the sidewall 6. The first ply 28 is folded around the core 22 from the inner side to the outer side in the axial direction. By this folding, the main portion 28a and the folding portion 28b are formed in the first ply 28. The second ply 30 is folded around the core 22 from the inner side to the outer side in the axial direction. By this folding, the main portion 30a and the folding portion 30b are formed in the second ply 30. The end of the folded portion 28b of the first ply 28 is located outside the end of the folded portion 30b of the second ply 30 in the radial direction.

  The first ply 28 and the second ply 30 are each composed of a large number of cords and topping rubbers arranged in parallel. 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 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 may be formed from a single ply.

  The band 12 is located outside the carcass 10 in the radial direction. The band 12 is located on the inner side in the radial direction of the tread 4. In the tire 2, the band 12 reinforces the carcass 10. In the tire 2, the band 12 constitutes a reinforcing layer.

  Although not shown, a belt may be provided. The belt is located on the radially inner side of the tread 4. The belt is laminated with the carcass 10. The belt reinforces the carcass. A reinforcing layer may be formed from the band 12 and the belt. The belt is composed of a large number of cords arranged in parallel and a topping rubber. Each cord extends with an inclination to the equator plane. A general absolute value of the tilt angle is set to 10 ° to 35 °. A preferred material for the cord is steel. An organic fiber may be used for the cord. The axial width of the belt is preferably 0.7 times or more the maximum width of the tire. The belt may comprise two or more layers. In the axial direction, the width of the band 12 is made larger than the width of the belt.

  The inner liner 14 is located inside the carcass 10. In the vicinity of the equator plane CL, the inner liner 14 is joined to the inner surface of the carcass 10. The inner liner is made of a crosslinked rubber. The inner liner is made of a crosslinked rubber having excellent air shielding properties. A typical base rubber for the inner liner is butyl rubber or halogenated butyl rubber. The inner liner maintains the internal pressure of the tire.

  The chafer 16 is located in the vicinity of the bead 8. When the tire 2 is assembled into a rim (not shown), the chafer 16 comes into contact with the rim. By this contact, the vicinity of the bead 8 is protected. The chafer 16 is made of, for example, a cloth and rubber impregnated in the cloth.

  FIG. 2 shows a strip 32 forming this band 12. The band 12 includes a cord 34 as a band cord and a rubber member 38 that is vulcanized to form a topping rubber 36. The strip 32 is an example of a strip used for the tire 2. The width of the strip 32 is, for example, 4.2 mm. In the strip 32, three cords 34 are driven. The cord 34 is a steel cord. The cord 34 may be made of an organic fiber. Examples of preferable organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

  FIG. 3 shows a part of the carcass 10 and the band 12 of the tire 2. FIG. 3 shows a diagram in which the carcass 10 and the band 12 are projected onto a cylindrical surface. The vertical direction in FIG. 3 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. An arrow Wb in FIG. 3 indicates the axial width of the band 12.

  The band 12 is superimposed on the outer peripheral surface 10 a of the carcass 10. The outer peripheral surface 12 a of the band 12 is overlaid on the base layer 20 of the tread 4.

  The band 12 is obtained by vulcanizing the strip 32. The band 12 includes a band body 40. The band body 40 includes a first main portion 42, a second main portion 44, and an end portion 46. The first main portion 42 extends from the one end of the band 12 to the other end while being inclined with respect to the circumferential direction. The second main portion 44 extends from the other end of the band 12 to one end while being inclined with respect to the circumferential direction. The end portions 46 are positioned at one end and the other end of the band 12 and extend in the circumferential direction. The 1st main part 42 and the 2nd main part 44 incline in the reverse direction with respect to the circumferential direction.

  A one-dot chain line L <b> 1 in FIG. 3 indicates the center line of the first main portion 42. An alternate long and short dash line L <b> 2 indicates a center line of the second main portion 44. A double-headed arrow θ1 indicates an angle formed by the center line L1 and the equator plane CL. This angle θ1 indicates the inclination angle of the first main portion 42. This angle θ1 is also the inclination angle of the cord 34 of the first main portion 42. A double arrow θ2 indicates an angle formed by the center line L2 and the equator plane CL. This angle θ <b> 2 indicates the inclination angle of the second main portion 44. This angle θ2 is also the inclination angle of the cord 34 of the second main portion 44. A double-headed arrow D indicates the length of the end portion 46 in the circumferential direction. A double-headed arrow P indicates the winding pitch of the band 40.

  The first main portion 42 of the band 40 extends in an inclined manner from one end of the band 12 in the axial direction to the other end. At the other end of the band 12, an end portion 46 extends in the circumferential direction continuously to the first main portion 42. Continuing from the end portion 46, the second main portion 44 extends in an inclined manner from the other end to the one end. At one end of the band 12, the other end 46 extends in the circumferential direction continuously to the second main portion 44. Further, the other first main portion 42 extends in an inclined manner from one end of the band 12 to the other end, following the other end portion 46. As described above, in the belt body 40, the portion including the first main portion 42, the end portion 46, the second main portion 44, and the other end portion 46 is continuously repeated in the circumferential direction. The band 40 is wound around the tire 2 in the circumferential direction. The band 12 is a so-called jointless band.

  As shown in FIG. 3, the first main portion 42 and the second main portion 44 intersect to form an intersecting portion 48. At the intersection 48, the first main portion 42 and the second main portion 44 overlap each other. By the vulcanization, the first main portion 42 and the second main portion 44 are integrated. In the intersecting portion 48, the cord 34 of the first main portion 42 and the cord 34 of the second main portion 44 intersect and extend.

  In this band 12, the band 40 extends in a lattice shape. The band 12 is formed by forming the band 40 into a net shape. The band 12 has a diamond-shaped gap (mesh). The diamond-shaped gap is formed with a long diagonal line in the circumferential direction and a short diagonal line in the axial direction. In the band 12, the band body 40 repeatedly forms the diamond-shaped gaps (mesh) at a pitch P in the circumferential direction.

  In the band 12, the cord 34 of the first main portion 42 restrains the cord 34 of the second main portion 44. The cord 34 of the second main portion 44 restrains the cord 34 of the first main portion 42. The cord 34 of the first main portion 42 and the cord 34 of the second main portion 44 are constrained to each other, and the band 12 has high rigidity. Further, since the jointless belt body 40 is formed by being wound in the circumferential direction, the band 12 can obtain a wrinkle effect. From the viewpoint of obtaining high rigidity and a high wrinkle effect, the cord 34 is preferably made of a steel cord.

  Since this highly rigid band 12 is provided, the tire 2 can obtain a high cornering power. The tire 2 contributes to improving the turning performance of the two-wheeled vehicle.

  FIG. 4 shows the relationship between the angles θ1 and θ2 of the cord 34 and the Corning power value CP of the tire 2. As shown in FIG. 4, the cornering power value CP increases as the absolute values of the angle θ1 and the angle θ2 increase from 0 °. When the angles θ1 and θ2 are 15 °, the cornering power value CP is maximized. Furthermore, as the angles θ1 and θ2 increase, the cornering power value CP gradually decreases.

  As shown in FIG. 4, the tire 2 having a large angle θ <b> 1 and θ <b> 2 has a large cornering power value. The tire 2 having a large cornering power value CP is excellent in turning performance. From this viewpoint, the angle θ1 and the angle θ2 are preferably 1 ° or more, more preferably larger than 3 °, and particularly preferably larger than 5 °.

  On the other hand, the tire 2 having a small cornering power value CP is excellent in steering stability during straight traveling. Moreover, this tire 2 is excellent in the absorbency of the shock received from the unevenness | corrugation of a road surface. In other words, the tire 2 is excellent in ride comfort. Furthermore, the tire 2 is also excellent in durability. From these viewpoints, the angle θ1 and the angle θ2 are preferably 10 ° or less, more preferably 9 ° or less, and particularly preferably 8 ° or less.

  The tire 2 having an absolute value of the angle θ1 and an absolute value of θ2 that are different from each other is likely to cause a left-right difference in turning. There is a tendency for a difference in turnability between left turn and right turn. From this point of view, the angle θ1 and the angle θ2 are preferably set to the same size.

  Since this band 12 has high rigidity, the number of turns in the circumferential direction is reduced compared to a conventional band having a jointless band (JLB) structure in which the cord is spirally wound in the circumferential direction. The rigidity equal to or better than that of the band can be obtained. In the band 12 of the tire 2, the end, which is the number of cords 34 driven per 5 cm in the axial width, is E1 (5/5 cm). The band 40 is wound substantially in the circumferential direction, and the end when the belt 40 is wound without any gap in the axial direction and without overlapping in the radial direction is defined as E (5/5 cm). At this time, with the end E1 (line / 5 cm) smaller than the end E (line / 5 cm), the tire 2 can obtain equal or higher rigidity. In the tire 2, this E1 (lines / 5 cm) is obtained as an average value in the band width Wb.

  The tire 2 having a small ratio E1 / E between the ends E1 (lines / 5 cm) and the ends E (lines / 5 cm) is excellent in handling stability and riding comfort. Further, since the number of windings of the strip 32 (band body 40) is small, the tire 2 is excellent in productivity and weight reduction. From these viewpoints, the ratio E1 / E is preferably 0.7 or less.

  On the other hand, the tire 2 having a large ratio E1 / E has high rigidity. The tire 2 is excellent in turning performance and durability. From these viewpoints, the ratio E1 / E is preferably 0.5 or more.

  In the tire 2, the end portion 46 is located between the first main portion 42 and the second main portion 44. The end portion 46 is continuous with the first main portion 42 and the second main portion 44, and functions as a folded portion between the first main portion 42 and the second main portion 44. The end 46 extends in the circumferential direction with a length D. By providing the end portion 46, the carcass 10 and the strip 32 can be easily bonded to each other at the folded portion of the strip 32 in the molding step before vulcanization. Since the tire 2 includes the end portion 46, the tire 2 is excellent in productivity. From this viewpoint, the length D is preferably 10 mm or more.

  In the present invention, the size and angle of each member of the tire 2 are measured in a state where the tire is incorporated in a regular rim and the tire is filled with air so as to have a regular internal pressure. In the present specification, the normal rim means a rim defined in a standard on which the tire 2 depends. “Standard rim” in the JATMA standard, “Design Rim” in the TRA standard, and “Measuring Rim” in the ETRTO standard are regular rims. In the present specification, the normal internal pressure means an internal pressure defined in a standard on which the tire 2 relies. “Maximum air pressure” in JATMA standard, “Maximum value” published in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in TRA standard, and “INFLATION PRESSURE” in ETRTO standard are normal internal pressures.

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

[Example 1]
A tire having the structure shown in FIGS. 1 and 3 was obtained. The front tire size was 120 / 70ZR17. The rear tire size was 180 / 55ZR17. The absolute value of the band cord inclination angle θ1 and the absolute value of θ2 of these tires were both 5 °. The tire end is E1 (pieces / 5 cm), and the end when the tire strip is wound substantially circumferentially without any gap in the axial direction and without overlapping in the radial direction is E ( Book / 5 cm). The ratio E1 / E at this time was 0.5.

[Comparative Example 1]
A tire was prepared in which the belt body of Example 1 was wound substantially in the circumferential direction in the circumferential direction. Other configurations were the same as in Example 1. This tire is a commercially available tire.

[Example 2-4]
A tire was obtained in the same manner as in Example 1 except that the ratio E1 / E was as shown in Table 1 below.

[Example 5-9]
A tire was obtained in the same manner as in Example 1 except that the absolute value of the band cord inclination angle θ1 and the absolute value of θ2 were as shown in Table 2 below.

[Example 10]
A tire was obtained in the same manner as in Example 1 except that the ratio E1 / E, the absolute value of the inclination angle θ1, and the absolute value of θ2 were as shown in Table 2 below.

[Evaluation of longitudinal spring constant]
The longitudinal spring constant of the front tire was measured under the following conditions.
Rim used: Regular rim Internal pressure: 250 kPa
Load: 1.5kN
The indexes when the spring constant of the tire of Comparative Example 1 is 100 are shown in Tables 1 and 2 below. The larger this index is, the larger the longitudinal spring constant is.

[Measurement of cornering power]
Using a flat belt type tire 6 component force measuring device, the cornering power value CP was measured with the front tire under the following measurement conditions.
Rim used: Regular rim Internal pressure: 250 kPa
Load: 1.5kN
Speed: 30km / h
Camber angle: 0 °
Slip angle: 1 °
The indexes when the cornering power value CP of the tire of Comparative Example 1 is set to 100 are shown in Tables 1 and 2 below. As this index increases, the cornering power value CP increases.

[Swivel, handling stability and ride comfort]
A tire was incorporated into a regular rim, and this tire was filled with air so as to have a regular internal pressure (front tire 250 kPa, rear tire 290 kPa). This tire was mounted on a motorcycle having a displacement of 1000 cm ³ (cc). The driver was allowed to drive the motorcycle on the racing circuit to evaluate the turning performance, the straight driving stability and the ride comfort. The results are shown in Table 1 below as an index. This index was evaluated in 10 steps, with Comparative Example 1 as the reference value of 5. A larger value is preferable.

[durability]
A front tire was incorporated into a regular rim, and the tire was filled with air to adjust the internal pressure to 235 kPa. This tire was mounted on a drum type traveling tester, and a longitudinal load of 2.86 kN was applied to the tire. This tire was run on a drum having a radius of 1.7 m at a speed of 80 km / h. The distance traveled until the tire broke was measured. The results are shown in Tables 1 and 2 below as indices. This index was evaluated in 10 steps, with Comparative Example 1 as the reference value of 5. A larger numerical value is preferable.

[Puncture resistance]
A plunger fracture test according to JIS-D4230 was performed under the condition that the tire was incorporated into a regular rim and filled with air of regular internal pressure. The breaking energy at that time was evaluated using Comparative Example 1 as a reference level. The fracture resistance equal to or higher than that of Comparative Example 1 was “good”, and the fracture resistance inferior to that of Comparative Example 1 was “bad”. The results are shown in Tables 1 and 2.

[Production cost]
The length of the strip forming the band was evaluated. This length correlates with the winding time of the strip. The indexes when the length of the strip of Comparative Example 1 is 100 are shown in Tables 1 and 2 below. The smaller the index, the shorter the strip length and the shorter the winding time.

  As shown in Table 1 and Table 2, in the example, the evaluation is higher than that in the comparative example. From this evaluation result, the superiority of the present invention is clear.

  The tire 2 described above can be widely applied as a tire for a motorcycle. The tire 2 can be applied to a radial tire that employs a jointless band (JLB). For example, the present invention can be applied to a rear tire of a motorcycle, a touring type front tire, and the like.

2 ... tyre 4 ... tread 6 ... side wall 8 ... bead 10 ... carcass 12 ... band 14 ... inner liner 16 ... chafer 18 ... tread surface 20 ... Base layer 22 ... Cap layer 24 ... Core 26 ... Apex 28 ... First ply 30 ... Second ply 32 ... Strip 34 ... Cord 36 ... Topping rubber 38 ... Rubber member 40 ... Band 42 ... First main part 44 ... Second main part 46 ... End part 48 ... Intersection

Claims (5)

A tread whose outer surface forms a tread surface, a pair of sidewalls each extending substantially inward in the radial direction from the end of the tread, a pair of beads each positioned radially inward of the sidewalls, and a tread and sidewalls A carcass spanned between one bead and the other bead along the inner side, and a band laminated with the carcass on the inner side in the radial direction of the tread,
This band consists of a jointless belt,
This belt consists of a band cord and topping rubber,
A plurality of first main parts wound around the belt in an inclined direction with respect to the circumferential direction, and a plurality of second main parts wound in an inclined direction opposite to the first main part with respect to the circumferential direction. Has
The band is formed in a net shape by crossing the plurality of first main portions and the plurality of second main portions ,
The end, which is the number of band cords driven per 5 cm width of the band, is E1 (lines / 5 cm). When the ending is set to E (5 / 5cm),
A tire for a two-wheeled vehicle in which the end E1 of this band is 0.5 to 0.7 times that of the end E.   2. The tire according to claim 1, wherein an absolute value of an inclination angle θ <b> 1 of the first main part band cord and an inclination angle θ <b> 2 of the second main part band cord is 1 ° or more and 10 ° or less.   The tire according to claim 1 or 2, wherein the absolute value of the inclination angle θ1 of the band cord of the first main portion and the absolute value of the inclination angle θ2 of the band cord of the second main portion are the same. The band has an end,
This end is located in the axial end of the band and extends in the circumferential direction,
The tire according to any one of claims 1 to 3 , wherein the end portion is located between the first main portion and the second main portion and is continuous with the first main portion and the second main portion. The tire according to any one of claims 1 to 4 , wherein the band cord is made of a steel cord.

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