JP4690098B2 - Pneumatic tires for motorcycles - Google Patents

Description

  The present invention relates to a pneumatic tire for a motorcycle used in a heavy-duty motorcycle having a large output, and particularly excellent in high-speed durability, handling at high speed and low speed, vibration absorption, and maneuvering near a high-speed cornering limit point. The present invention relates to a pneumatic tire for a motorcycle that can improve a sense of stability.

  In conventional pneumatic tires for two-wheeled vehicles in the era of low power-weight ratio (weight per unit horsepower) (for example, 4 kg / PS or more), one or two layers of nylon carcasses with low turn-back height are combined with aromatic polyamide. A wide belt breaker layer called a cap ply using a cord is stacked, and a main belt layer formed by winding a spiral belt using an aromatic polyamide cord in the tire circumferential direction is disposed on the breaker layer.

As another conventional example, the carcass ply is wound up to a position where it overlaps (overlaps with) the belt layer (FIG. 2 and Patent Document 1), and the cap ply is disposed so as to overlap with the wound carcass. (Patent Document 2), a cap ply end portion disposed between a carcass and a bead filler rubber (Patent Document 3), and the like are disclosed.
JP 2000-21113 A Japanese Patent Laid-Open No. 6-16006 JP-A-9-156326

  Pneumatic tires used in high-powered heavy-duty motorcycles in recent years with a significantly improved power-to-weight ratio use the minimum number of components and minimize the increase in weight by combining them to maximize tire performance. It is necessary to draw out to the limit.

  However, in the above-described conventional example, there is no suggestion regarding optimization of a member property selection range and optimization of a structural arrangement combination of these members in order to maximize tire performance.

  In particular, there is no suggestion regarding optimization of the combination of cord strength between the spirally wound main belt layer and the breaker layer, optimization of the thermal characteristic selection range of the breaker cord, and the like.

  Also, in designing pneumatic tires for use in high-power heavy-duty motorcycles, simply combining three or four conventional technologies has a strong structure suitable for high-power and heavy weight, and high-speed durability. Tires with excellent handling characteristics and vibration absorption at high and low speeds, and excellent handling stability near the high-speed cornering limit point are efficient without increasing the number of parts and without excessive weight increase. It was difficult to design.

  Even if we allow a lot of trial and error while allowing a certain amount of weight increase, we can make a tire that meets the requirements of high speed durability and can be cornered at high speed, Obtaining a tire with an easily predictable grip limit point was and would not be within the scope of the prior art.

  In consideration of the above-mentioned facts, the present invention is a pneumatic tire for a motorcycle used for a heavy-duty motorcycle having a large output, and is excellent in high-speed durability, high-speed and low-speed handling properties, vibration absorption, and high-speed cornering limits. The object is to improve the handling stability in the vicinity of the point.

The invention of claim 1 includes a pair of bead portions, a carcass layer disposed between the pair of bead portions in a toroidal shape, and at least one layer disposed on the outer side in the tire radial direction of the carcass layer. In the pneumatic tire for a motorcycle , the carcass layer includes: a breaker of claim 2; and at least one main belt layer formed by spirally winding a rubber-coated belt cord radially outward of the breaker. An up-ply carcass having at least one layer having a carcass body portion straddling between the pair of bead portions and a folded portion wound around a bead core of the bead portion from the inside to the outside, and disposed so as to overlap the up-ply carcass have been and a down ply carcass of at least one layer, the carcass cords in the carcass layer, the JIS L 1017-1982 According Test methods, test temperature 30 ° C., when the tensile elongation of 2%, code 1 real Rino strength is not less than 140 N, the code direction 65 to 85 ° with respect to the tire circumferential direction, with the ply adjacent to the Crossing each other, the number of driving is 25 to 65 per 50 mm, and the folded portion of the upply carcass has a height from the bead portion side reference line of the tire cross-sectional height to the folded end. 50 to 75% of the cross-sectional height, and the folded end overlaps with the breaker, and the end of the down ply carcass is not rolled back on the bead core, and the carcass of the up ply carcass The breaker cord is sandwiched between the main body and the bead core and terminated, and the breaker cord in the breaker is JIS L 1017-198. According to the test method 2, when the test temperature is 30 ° C. and the tensile elongation is 2%, the strength per cord is 300 N or more, the heat shrinkage is 177 ° C. and 3% or less, and the cord direction is in the tire circumferential direction. In contrast, the carcass cords of the carcass layer located at the outermost layer in the tire radial direction intersect with each other at 65 to 85 °, and the number of driving is 30 to 65 per 50 mm, and both ends in the width direction of the breaker are , Extending from the bead portion side reference line of the tire cross-section height to a position of 25 to 60% with respect to the tire cross-section height outward in the tire radial direction, and overlapping with the folded portion of the upply carcass And both end portions in the width direction of the main belt layer extend from the bead portion side reference line of the tire cross-section height to a position of 45 to 70% with respect to the tire cross-section height outward in the tire radial direction. And the overlap portion of the up-ply carcass overlaps, the strength ratio of the belt cord and the breaker cord is 1.1 to 1.4, and the number of driven belt cords is 20 to 50 mm. It is characterized by 110.

  Here, in the carcass layer, the strength of the carcass cord is set to 140 N or more because the tire case body has a desired strength even if the carcass layer is only two layers, for example, the up ply carcass and the down ply carcass. This is to make it possible.

  Note that the strength of the cord (tensile strength, unit N) is as per cord when the test temperature is 30 ° C. and the tensile elongation is 2% by Shimadzu Autograph according to the test method of JIS L 1017-1982. Value.

  Moreover, the reason why the angle of the carcass cord is set to 65 to 85 ° with respect to the tire circumferential direction is that if the angle is less than 65 °, the rigidity in the tire circumferential direction is inferior. Because it is inferior.

  The reason why the number of driven carcass cords is 25 to 65 per 50 mm is that when the number is less than 25, it is difficult to ensure the rigidity of the tire case without adding a reinforcing layer or the like. This is because the cord interval is too narrow to easily induce cord fretting and the like, and the durability of the carcass layer is inferior.

  In the folded portion of the up-ply carcass, the height from the bead portion side reference line of the tire cross-section height to the turn-up end is set to 50 to 75% with respect to the tire cross-section height. This is because the reinforcing effect is inferior. If it exceeds 75%, the folded end is too close to the contact center region of the tread, and the durability (separation resistance, etc.) of the folded end is inferior.

  The tire cross-sectional height here refers to the maximum load in the applicable size / ply rating specified in the YEAR BOOK when the tire is assembled to a standard rim in the applicable size specified in the 2004 YEAR BOOK issued by JATMA. It refers to the height of the cross section in an unloaded state filled with 80% of the air pressure.

  When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards are followed.

  In the pneumatic tire for a motorcycle according to claim 1, the member physical property selection range in the carcass layer is optimized and the structural arrangement combination of the members is optimized as described above. Even if this increase is suppressed, the tire case body can have a desired strength.

  In particular, the folded end of the carcass layer is raised and sandwiched between the breaker and the carcass main body, and the folded end is restrained to suppress variations in the tire radial direction, thereby increasing the rigidity of the tire case. And the number of plies from the end of the main belt layer to the bead portion is substantially equalized, the case rigidity step in the region can be reduced, and steering stability during cornering (camber running) when the tire is tilted Can be improved.

  Next, in the breaker, the reason why the strength of the breaker cord is set to 300 N or more is to allow the crown portion of the tire to be reinforced so as to have a desired strength even if the breaker has at least one layer.

  Further, the reason why the thermal contraction amount of the breaker cord is set to 3% or less at 177 ° C. is that if it exceeds this, the main belt layer is disturbed and the durability of the crown portion is inferior.

  The reason why the angle of the breaker cord is set to 65 to 85 ° with respect to the tire circumferential direction is that when the angle is less than 65 °, the rigidity in the tire axial direction is lowered and the handling characteristics at high speed and low speed are inferior. This is because, if it exceeds °, the rigidity in the tire circumferential direction is lowered and the high-speed durability is inferior.

  The reason why the number of breaker cords to be driven is 30 to 65 per 50 mm is that if the number is less than 30, the reinforcing effect of the crown portion is inferior. If the number exceeds 65, the cord interval is too narrow and code fretting, etc. This is because the durability of the breaker is inferior.

  The reason why the both ends in the width direction of the breaker are set to 25 to 60% of the tire cross-section height from the bead-side reference line of the tire cross-section height to the tire cross-section height is below 25%, This is because the reinforcing effect is inferior. Moreover, if it exceeds 60%, it will be reinforced too much to the area close to the originally strong bead part, and the balance of the case rigidity in the side wall part area from the width direction both ends of the main belt layer to the bead part will be lost, This is because the feeling of steering stability during cornering (during camber travel) decreases.

  In the pneumatic tire for a motorcycle according to claim 1, the member physical property selection range in the breaker is optimized as described above, and the structural arrangement combination of the members is optimized, so that the crown portion is reinforced to a desired strength. it can. As a result, cornering performance, vibration absorption, and handling stability in the vicinity of the high-speed cornering limit point can be enhanced.

  In particular, by adopting a breaker cord having a heat shrinkage of 177 ° C. of 3% or less, a step at the folded end of the carcass layer during winding of the main belt layer is smoothed, and the main belt layer is disturbed. In addition, the main belt layer can be prevented from being disturbed by the thermal contraction of the breaker cord during high-temperature vulcanization, and the durability of the crown portion can be improved.

  In addition, since both ends in the width direction of the breaker are arranged at appropriate height positions, the number of plies in the sidewall portion region is substantially equalized, and the case rigidity step in the region can be reduced. Steering stability during camber travel can be improved.

  Since the breaker cord and the outermost carcass cord cross each other, the crown portion can have a desired strength.

  Next, in the main belt layer, both end portions in the width direction are 45% to 70% with respect to the tire cross section height outward from the bead portion side reference line of the tire cross section height in the tire radial direction. It is because reinforcement will be excessive when it is less than 70%, and it is inferior to reinforcement when it exceeds 70%. More preferably, the height of both end portions in the width direction of the main belt layer is 55 to 65% with respect to the tire cross section height outward in the tire radial direction from the bead portion side reference line of the tire cross section height. .

  The reason why the strength ratio between the belt cord and the breaker cord is 1.1 to 1.4 is that if it is below 1.1, the grip limit becomes peaky and the handling stability is inferior, and it exceeds 1.4. This is because the reinforcement of the crown portion is inferior.

  The number of belt cords to be driven is set to 20 to 110 per 50 mm. If the number is less than 20, the high-speed durability is inferior. If the number exceeds 110, the cord interval is too narrow and cord fretting is likely to occur. This is because the durability of the main belt layer is inferior.

  In the pneumatic tire for a motorcycle according to claim 1, in addition to the strong tire case structure in which the rigidity difference of the side wall portion is eliminated and the strong crown portion reinforcing structure, the main belt layer is provided with the main tire layer inside. A combination of a belt cord of the belt layer and a breaker having a breaker cord with an appropriate strength ratio (combination type crown reinforcement structure) improves vibration absorption and high-speed and low-speed handling, and limits high-speed cornering It is possible to increase the sense of handling stability in the vicinity.

  In addition, both ends of the main belt layer in the width direction overlap (overlap) the folded end of the upply carcass, so that lifting of the folded end during high-speed rotation of the tire is suppressed and high-speed durability is improved. To do.

  Note that the width of the main belt layer in the tire axial direction is substantially the same as the tread width, for example, 90 to 110% of the tread width.

The invention according to claim 2 is the pneumatic tire for a motorcycle according to claim 1, wherein the belt cord is a cord at a test temperature of 30 ° C. and a tensile elongation of 2% according to a test method of JIS L 1017-1982. It is characterized by a textile cord having a strength of 350N or more per one .

  Here, the reason why the belt cord has a strength of 350 N or more is to allow the crown portion to have a desired strength even with only one belt layer, for example.

  In the pneumatic tire for a motorcycle according to claim 2, a textile cord having a strength of 350 N or more is used as a belt cord in the main belt layer, and the main belt layer is disposed under a strong balance with the breaker. As a result, the crown portion can have a desired strength, whereby high-speed durability and vibration absorption can be improved.

According to a third aspect of the present invention, there is provided the pneumatic tire for a motorcycle according to the first aspect, wherein the belt cord is a cord at a test temperature of 30 ° C. and a tensile elongation of 2% according to a test method of JIS L 1017-1982. It is characterized by a steel cord having a strength per 330N or more.

  Here, the reason why the strength of the belt cord is set to 330 N or more is to allow the crown portion to have a desired strength even with only one belt layer, for example.

  In the pneumatic tire for a motorcycle according to claim 3, a steel cord having a strength of 330 N or more is used as a belt cord in the main belt layer, and the main belt layer is disposed under a strong balance with the breaker. Therefore, it is possible to give the crown portion a higher strength than when a textile cord is used, thereby improving high-speed durability and vibration absorption.

  According to a fourth aspect of the present invention, in the pneumatic tire for a motorcycle according to the first aspect, the belt cord is an aromatic polyamide, and the main belt layer is one layer.

  The aromatic polyamide is, for example, aramid.

  In the pneumatic tire for a motorcycle according to claim 4, since the aromatic polyamide is used for the belt cord, high-speed durability and vibration absorption can be improved including weight reduction.

  As the belt cord, for example, an aromatic polyamide cord of 1500 d / 2 is preferably used.

  According to a fifth aspect of the present invention, in the pneumatic tire for a motorcycle according to any one of the first to fourth aspects, the carcass cord is a rayon, and the carcass layer is the two layers of the up-ply carcass. And one layer of the down ply carcass.

  In the pneumatic tire for a motorcycle according to claim 5, since the carcass cord uses rayon having high strength among the textile cords, the number of carcass layers can be reduced.

  For example, a 1680 d / 2 rayon cord is preferably used as the carcass cord.

  According to a sixth aspect of the present invention, in the pneumatic tire for a motorcycle according to any one of the first to fifth aspects, the breaker cord is an aromatic polyamide, and the breaker is a single layer. It is a feature.

  In the pneumatic tire for a motorcycle according to claim 6, since aromatic polyamide is used for the breaker cord and the breaker is made of one layer, high-speed durability and vibration absorption can be improved including weight reduction. As the breaker cord, for example, an aromatic polyamide cord of 1000 d / 2 is preferably used.

  As described above, according to the pneumatic tire for a motorcycle of the present invention, in a pneumatic tire for a motorcycle used in a heavy-duty motorcycle having a large output, high-speed durability, handling performance at high speed and low speed, vibration absorption In addition, it has an excellent effect of improving the handling stability in the vicinity of the high-speed cornering limit point.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. A pneumatic tire 10 for a motorcycle according to the present embodiment is a tire used for a high-power heavy vehicle. In FIG. 1 which is a reference diagram, a pair of bead parts 12, a carcass layer 14, a breaker 16, A main belt layer 18.

  In the pneumatic tire 10, a sidewall portion 28 is formed continuously with the pair of bead portions 12 fitted to the rim 34, and a tread 30 is formed with the sidewall portions 28 on both sides.

  The carcass layer 14 is disposed so as to straddle between the pair of bead portions 12, and is folded around the carcass main body portion 20 </ b> A straddling between the pair of bead portions 12 and the bead core 22 of the bead portion 12 from the inside to the outside. It has at least one layer of up-ply carcass 20 having a portion 20B, and at least one layer of down-ply carcass 24 disposed so as to overlap the up-ply carcass 20.

  In the present embodiment, the carcass layer 14 includes, for example, two layers of up-ply carcass 20 and one layer of down-ply carcass 24.

  A bead filler 26 made of, for example, hard rubber is disposed in a region surrounded by the bead core 22, the carcass main body 20A, and the folded portion 20B.

  A carcass cord (not shown) in the carcass layer 14 has, for example, a strength of 140 N or more. The reason why the strength of the carcass cord is 140 N or more is that the tire case body can have a desired strength even if the carcass layer 14 is only two layers, for example, the up ply carcass 20 and the down ply carcass 24. It is to do.

  As the carcass cord, for example, a 1680d / 2 cord made of rayon is preferably used.

  The cord direction of the carcass cord intersects each other in each layer of the carcass layer 14 at 65 to 85 ° with respect to the tire circumferential direction. The reason why the angle of the carcass cord is 65 to 85 ° with respect to the tire circumferential direction is that the rigidity in the tire circumferential direction is inferior when the angle is less than 65 °, and the rigidity in the tire radial direction is inferior when the angle exceeds 85 °. Because.

  The number of carcass cords to be driven is 25 to 65 per 50 mm. This is because if the number is less than 25, it is difficult to ensure the rigidity of the tire case without adding a reinforcing layer or the like. If the number exceeds 65, the cord interval is too narrow and induces code fretting and the like. This is because the durability of the carcass layer 14 is inferior.

  The folded portion 20B of the upply carcass 20 has a height CH from the bead portion side reference line BL of the tire sectional height SH to the folded end 20C of 50 to 75% with respect to the tire sectional height SH. This is because the reinforcing effect is inferior when it is less than 50%, and when it exceeds 75%, the folded end 20C is too close to the contact center region of the tread, and the durability (separation resistance, etc.) of the folded end 20C. Because it is inferior.

  Further, the folded end 20C overlaps the breaker 16, and the end portion of the down ply carcass 24 is sandwiched between the carcass body portion 20A of the up ply carcass 20 and the bead core 22 without being wound around the bead core 22. It is terminated.

  At least one breaker 16 is disposed on the outer side of the carcass layer 14 in the tire radial direction, and a breaker cord (not shown) in the breaker 16 has a strength of 300 N or more.

  The reason why the strength of the breaker cord is set to 300 N or more is to allow the crown portion to be reinforced so as to have a desired strength even if the breaker 16 has at least one layer, for example. The breaker cord is preferably a 1000 d / 2 cord made of aromatic polyamide, for example.

  The thermal contraction amount of the breaker cord is 3% or less at 177 ° C. This is because, if it exceeds 3%, the main belt layer 18 is disturbed and the durability of the crown portion is inferior.

  The cord direction of the breaker cord is 65 to 85 ° with respect to the tire circumferential direction, and intersects with the carcass cord of the carcass layer 14 located in the outermost layer in the tire radial direction.

  The reason why the angle of the breaker cord is set to 65 to 85 ° with respect to the tire circumferential direction is that when the angle is less than 65 °, the rigidity in the tire axial direction is lowered and the handling characteristics at high speed and low speed are inferior. This is because, if it exceeds °, the rigidity in the tire circumferential direction is lowered and the high-speed durability is inferior.

  The number of breaker cords to be driven is 30 to 65 per 50 mm. This is because when the number is less than 30, the reinforcing effect of the crown portion is inferior. When the number exceeds 65, the cord interval is too narrow, and it becomes easy to induce cord fretting and the like, and the breaker 16 has poor durability. It is.

  Both end portions 16A in the width direction of the breaker 16 extend from the bead portion side reference line BL of the tire cross-section height SH to a position (height BH) 25 to 60% of the tire cross-section height SH outward in the tire radial direction. It extends and overlaps with the folded portion 20B of the upply carcass 20 (overlaps).

  The reason why the width direction end portions 16A of the breaker 16 are set to 25 to 60% from the bead portion side reference line BL of the tire cross section height SH to the tire radial direction outward with respect to the tire cross section height SH is less than 25%. This is because the reinforcing effect of the crown portion is inferior. Further, if it exceeds 60%, the region close to the originally strong bead portion 12 is excessively reinforced, and the case rigidity in the region of the sidewall portion 28 from the both ends in the width direction of the main belt layer 18 to the bead portion 12 is increased. This is because the balance of the vehicle is lost and the feeling of steering stability during cornering (during camber travel) decreases.

  The main belt layer 18 is formed by winding a rubber-coated belt cord 32 spirally outward in the tire radial direction of the breaker 16, and is provided with at least one layer.

  The belt cord 32 has a strength of 350 N or more, and is preferably a 1500 d / 2 textile cord made of aromatic polyamide, for example.

  The reason why the strength of the belt cord 32 is set to 350 N or more is to allow the crown portion to have a desired strength even with only one belt layer, for example.

  Both end portions 18A in the width direction of the main belt layer 18 are positioned 55% to 65% from the bead portion side reference line BL of the tire cross-section height SH with respect to the tire cross-section height SH, for example, 55% to 65% (high). To BEH). This is because the rigidity of the crown portion is insufficient when it is less than 55%, and the rigidity of the sidewall portion 28 is insufficient when it exceeds 65%.

  Both end portions 18 </ b> A in the width direction of the main belt layer 18 overlap the folded portion 20 </ b> B of the upply carcass 20.

  The strength ratio between the belt cord 32 and the breaker cord is 1.1 to 1.4. This is because if it is below 1.1, the grip limit becomes peaky and the steering stability is poor, and if it exceeds 1.4, the reinforcement of the crown portion is inferior.

  The number of driven belt cords 32 is 20 to 110 per 50 mm. This is because when the number is less than 20, the high-speed durability is inferior, and when the number is more than 110, the cord interval is too narrow to easily induce cord fretting and the like, and the durability of the main belt layer 18 is inferior.

  For example, a 1680 d / 2 rayon cord is used as the carcass cord, an aromatic polyamide cord of 1000 d / 2 is used as the breaker cord, and an aromatic polyamide cord of 1500 d / 2 is used as the belt cord, for example. Most preferably used in combination. This is because an increase in the number of members in the pneumatic tire 10 for motorcycles and an excessive increase in weight can be suppressed by using a material that is lightweight but strong.

As described above, in the pneumatic tire 10 for a motorcycle according to the present embodiment, the width direction both ends 18A of the main belt layer 18, the width direction both ends 16A of the breaker 16, the down ply carcass 24, and the up ply carcass 20 (carcass body portion 20A and turn-up portion 20B) partially overlap each other (OL range shown in FIG. 1).
(Function)
In the pneumatic tire 10 for a motorcycle, the member physical property selection range in the carcass layer 14 is optimized as described above, and the structural arrangement combination of the members is optimized, thereby suppressing an increase in the number of members due to the addition of a reinforcing layer or the like. Even so, the tire case body can have a desired strength.

  In particular, the folded end 20C of the carcass layer 14 is raised and sandwiched between the breaker 16 and the carcass main body 20A, and the folded end 20C is restrained to suppress variations in the tire radial direction. Rigidity can be increased, and the number of plies from the end of the main belt layer 18 to the bead portion 12 can be substantially equalized, the case rigidity step in the region can be reduced, and cornering when the tire is tilted (camber) The driving stability during driving can be improved.

  Further, in the pneumatic tire 10 for a motorcycle, since the member physical property selection range in the breaker 16 is optimized and the structural arrangement combination of the members is optimized as described above, the crown portion can be reinforced to a desired strength. As a result, cornering performance, vibration absorption, and handling stability in the vicinity of the high-speed cornering limit point can be enhanced.

  In particular, by adopting a breaker cord having a heat shrinkage of 177 ° C. and 3% or less, a step at the folded end 20C of the carcass layer 14 during winding of the main belt layer 18 is smoothed, and the main belt layer 18 is suppressed, and also the main belt layer 18 is prevented from being disturbed by the thermal contraction of the breaker cord during high-temperature vulcanization, so that the durability of the crown portion can be improved.

  In addition, since both end portions 16A in the width direction of the breaker 16 are arranged at appropriate height positions, the number of plies in the sidewall portion 28 region is substantially equalized, and the case rigidity step in the region is reduced. This can improve the handling stability during camber travel.

  Since the breaker cord and the outermost carcass cord cross each other, the crown portion can have a desired strength.

  Further, in the pneumatic tire 10 for a motorcycle, in addition to a strong tire case structure in which the rigidity difference of the sidewall portion 28 is eliminated and a strong crown portion reinforcing structure, the main belt is disposed inside the main belt layer 18. Since the belt cord 32 of the layer 18 and the breaker 16 having a breaker cord having an appropriate strength ratio are disposed in combination (combination type crown portion reinforcing structure), vibration absorption and high-speed and low-speed handling properties are improved, and high-speed cornering is performed. It is possible to enhance the handling stability in the vicinity of the limit point.

  For this reason, when the pneumatic tire 10 for a motorcycle is mounted on a motorcycle (not shown), it becomes possible to enter the corner at a higher speed than ever before, so that cornering time can be shortened particularly in a race.

  Further, since both end portions 18A in the width direction of the main belt layer 18 overlap (overlap) the folded end 20C of the upply carcass 20, lifting of the folded end 20C during high-speed rotation of the tire is suppressed, High speed durability is improved.

  As the belt cord 32 in the main belt layer 18, a textile cord having a strength of 350 N or more is used, and the main belt layer 18 is disposed under a strong balance with the breaker 16. Thus, high-speed durability and vibration absorption can be improved.

In the pneumatic tire 10 for a motorcycle, since the aromatic polyamide is used for the belt cord 32, high-speed durability and vibration absorption can be improved including weight reduction.
(Test example)
The pneumatic tires according to Example 1, Example 2 and the conventional example (FIG. 2) manufactured under the conditions shown in Table 1 are attached to the rear wheel of the motorcycle with a power-weight ratio of 3.2 kg / PS, and high-speed durability is achieved. The test was conducted on the performance, cornering performance, vibration absorption, and steering stability at high speed cornering.

The test vehicle is Vulcan 2000 manufactured by Kawasaki Heavy Industries, Ltd., which has a displacement of 2000 cc, a dry weight of 340 kg, and an output of 103 PS.
The tire size was 200 / 60R16M / C for the rear wheels and 150 / 80R16M / C for the front wheels, and the front wheels were fitted with the pneumatic tires for motorcycles according to the present invention.

  In FIG. 2, 100 is a pneumatic tire according to a conventional example, 102 is a carcass layer, 104 is a main belt layer, 106 is a bead portion, 108 is a bead core, 110 is a bead filler, 112 is a down ply carcass, and 114 is an up ply carcass. , 116 is a tread, and 118 is a rim.

  In Table 1, “2pUp-1pDown” in the structure of the carcass layer indicates that the upply carcass has two layers and the downply carcass has one layer, and “1pUp-1pDown” It shows that the carcass is one layer and the down ply carcass is one layer.

  Further, “SH” in the folded height of the carcass layer and the end portion height of the breaker is the tire cross-sectional height. The folded height of the carcass layer is the height from the bead side reference line of the tire cross section height to the outer side in the tire radial direction, and the end height of the breaker is from the bead side reference line of the tire cross section height. It is the height outward in the tire radial direction.

  Each test was performed by assembling each tire on a standard rim at an applicable size defined in JATMA YEAR BOOK issued in 2004 and filling the air pressure for the maximum load in the applicable size / ply rating.

  For high-speed durability, on a drum tester with a diameter of 1.7 m, a load of 65% of the maximum load is applied, the vehicle is continuously run at a speed of 210 km / h, and the time to tire failure is 100 times the conventional example. It is shown by the index. The larger the value, the better the result.

  The cornering performance, vibration absorption, and handling stability during high-speed cornering were tested on the actual vehicle and evaluated by the occupant feeling. These are also shown by an index with the conventional example being 100, and the larger the value, the better the result.

  According to this test example, the results of Example 1 and Example 2 are better than the conventional example for each evaluation item, and the performance of Example 1 is well balanced with each evaluation item. In Example 2, it was found that the improvement in handling stability at the time of high-speed durability and high-speed cornering was remarkable.

It is a reference figure showing the section of the pneumatic tire for motorcycles. It is sectional drawing of the pneumatic tire for two-wheeled vehicles which concerns on a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Pneumatic tire for two-wheeled vehicles 12 Bead part 14 Carcass layer 16 Breaker 16A Both ends in the width direction 18 Main belt layer 18A End part in the width direction 20 Up ply carcass 20A Carcass body part 20B Turned part 20C Turned end 22 Bead core 24 Down ply carcass 30 Tread 32 Belt cord SH Tire cross section height BL Tire cross section height bead side reference line

Claims (6)

A pair of bead portions, a carcass layer disposed between the pair of bead portions in a toroidal shape, at least one breaker disposed outward in the tire radial direction of the carcass, and rubber-coated In a pneumatic tire for a motorcycle , comprising: at least one main belt layer formed by spirally winding a belt cord outward in the tire radial direction of the breaker;
The carcass layer includes at least one layer of an up-ply carcass having a carcass body portion straddling between the pair of bead portions and a folded portion wound around a bead core of the bead portion from the inside to the outside. Having at least one layer of down ply carcass arranged to overlap,
The carcass cord in the carcass layer has a strength per cord of 140 N or more at a test temperature of 30 ° C. and a tensile elongation of 2% according to the test method of JIS L 1017-1982 , and the cord direction is the tire circumferential direction. The adjacent plies cross each other at 65 to 85 ° with respect to each other, and the number of driving is 25 to 65 per 50 mm,
The folded portion of the upply carcass has a height from the bead portion side reference line of the tire cross section height to the folded end of 50 to 75% of the tire sectional height, and the folded end is Overlaps with the breaker,
The end portion of the down ply carcass is terminated by being sandwiched between the carcass main body portion of the up ply carcass and the bead core without being rewound in the bead core,
The breaker cord in the breaker is in accordance with the test method of JIS L 1017-1982. When the test temperature is 30 ° C. and the tensile elongation is 2%, the strength per cord is 300 N or more and the heat shrinkage is 177 ° C. and 3%. The cord direction is 65 to 85 ° with respect to the tire circumferential direction, intersects with the carcass cord of the carcass located in the outermost layer in the tire radial direction, and the number of driving is 30 to 65 per 50 mm. Yes,
Both end portions in the width direction of the breaker extend from the bead portion side reference line of the tire cross-section height to a position of 25 to 60% with respect to the tire cross-section height outward in the tire radial direction, and the upply It overlaps with the folded part of the carcass,
Both end portions in the width direction of the main belt layer extend from the bead portion side reference line of the tire cross-section height to a position 45 to 70% of the tire cross-section height outward in the tire radial direction, and It overlaps with the folded portion of the upply carcass,
A pneumatic tire for a motorcycle, wherein a strength ratio between the belt cord and the breaker cord is 1.1 to 1.4, and the number of driven belt cords is 20 to 110 per 50 mm. . The belt cord is a textile cord having a strength per cord of 350 N or more at a test temperature of 30 ° C and a tensile elongation of 2% according to a test method of JIS L 1017-1982. The pneumatic tire for motorcycles according to 1. The belt cord is a steel cord having a strength per cord of 330 N or more at a test temperature of 30 ° C and a tensile elongation of 2% according to a test method of JIS L 1017-1982. The pneumatic tire for motorcycles according to 1. The belt cord is an aromatic polyamide,
The pneumatic tire for a motorcycle according to claim 1, wherein the main belt layer is a single layer. The carcass cord is rayon,
5. The motorcycle air according to claim 1, wherein the carcass layer has two layers of the up-ply carcass and one layer of the down-ply carcass. Enter tire. The breaker cord is an aromatic polyamide,
The pneumatic tire for a motorcycle according to any one of claims 1 to 5, wherein the breaker has one layer.

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