Tire for a motorized two-wheeled vehicle

Abstract

Provided is a motorcycle tire that can balance cornering performance and durability. A motorcycle tire (1) includes a carcass (6) and a tread reinforcing layer (7) disposed on the outer side of the carcass in the tire radial direction in a tread portion (2). The tread reinforcing layer includes a belt layer (8) in which a plurality of belt cords (8a) are arranged and a crown layer (9) in which a plurality of crown cords (9a) are arranged. The belt layer is composed of one inner belt ply (8A) disposed adjacent to the carcass and one outer belt ply (8B) disposed on the outer side of the inner belt ply in the tire radial direction. The crown layer is composed of at least one crown ply (9A) disposed between the inner belt ply and the outer belt ply in the tire radial direction adjacent to the inner belt ply and the outer belt ply. The development width (W1) of the outer belt ply is larger than the development width (W2) of the inner belt ply.

Description

Technical Field

[0001] This disclosure relates to tires for motorized two-wheeled vehicles that can balance cornering performance and durability. Background Technology

[0002] In the past, in order to improve cornering performance, it is known that motor vehicle tires include a tread reinforcement layer in the tread. For example, Patent Document 1 below discloses a motor vehicle tire in which the tread reinforcement layer is composed of two belt ply layers disposed on the outer side of the tire carcass in the tire radial direction and one crown ply layer disposed on the outer side of the two belt ply layers in the tire radial direction.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2018-111375

[0004] However, in the tire for motorized two-wheeled vehicles of Patent Document 1, the large lateral resistance is generated due to the hooping effect of the two belted cord layers. When the centrifugal force is small, such as when transitioning from a straight-line state to a gentle turn, there is a tendency for the force required to lift the motorized two-wheeled vehicle to increase. Therefore, in the tire for motorized two-wheeled vehicles of Patent Document 1, it is desirable to further improve the cornering performance when the centrifugal force is small, and it is also desirable to improve the durability performance. Summary of the Invention

[0005] This disclosure is made in view of the above-mentioned actual situation, and its main purpose is to provide a tire for motorized two-wheeled vehicles that can take into account both cornering performance and durability.

[0006] This disclosure relates to a tire for motorized two-wheeled vehicles, comprising: a carcass extending from the tread portion through a pair of sidewall portions to a pair of bead portions; and a tread reinforcement layer disposed on the outer side of the carcass in the tread portion in the tire radial direction. The tread reinforcement layer comprises a belt layer with a plurality of belt cords arranged therein and a crown belt layer with a plurality of crown cords arranged therein. The belt layer consists of an inner belt cord layer disposed adjacent to the carcass and an outer belt cord layer disposed on the outer side of the inner belt cord layer in the tire radial direction. The crown belt layer consists of... The system comprises at least one crown belt cord layer disposed adjacent to the inner belt cord layer and the outer belt cord layer between the inner belt cord layer and the outer belt cord layer. The belt cords of the inner belt cord layer are arranged at a first angle greater than 5° relative to the tire circumference, the belt cords of the outer belt cord layer are arranged at a second angle greater than 5° relative to the tire circumference, and the crown cords of the crown belt cord layer are arranged at an angle less than 5° relative to the tire circumference. The unfolded width of the outer belt cord layer is greater than the unfolded width of the inner belt cord layer.

[0007] The disclosed tire for motorized two-wheeled vehicles, by having the above-described structure, can balance cornering performance and durability. Attached Figure Description

[0008] Figure 1 This is a cross-sectional view showing one embodiment of the tire for motorized two-wheeled vehicles disclosed herein.

[0009] Figure 2 This is a diagram showing the unfolded structure of the tire tread reinforcement layer.

[0010] Figure 3 This is an enlarged cross-sectional view of the tummy rim.

[0011] Label Explanation

[0012] 1: Tire for motorized two-wheeled vehicles; 2: Tread layer; 6: Tire body; 7: Tread reinforcement layer; 8: Belt layer; 8A: Inner belt ply; 8B: Outer belt ply; 8a: Belt cord; 9: Crown layer; 9A: Crown ply; 9a: Crown cord. Detailed Implementation

[0013] Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings.

[0014] Figure 1 This is a radial cross-sectional view of the tire 1 (hereinafter, sometimes simply referred to as "tire 1") of the motorized two-wheeled vehicle in the present embodiment, in its normal state.

[0015] Here, "normal condition" means that tire 1 is assembled on a normal rim, adjusted to normal internal pressure, and is unloaded. In this specification, unless otherwise specified, the dimensions of tire 1 are values ​​measured under normal conditions.

[0016] In addition, "standard rim" refers to a rim with a specific specification for each tire within a specification system that includes the specification on which tire 1 is based. For example, if it is JATMA, it is "standard rim", if it is TRA, it is "Design Rim", and if it is ETRTO, it is "Measuring Rim".

[0017] In addition, "standard internal pressure" is the air pressure determined for each tire in the specification system, including the specification on which tire 1 is based. If it is JATMA, it is "maximum air pressure". If it is TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITSAT VARIOUS COLD INFLATION PRESSURES". If it is ETRTO, it is "INFLATION PRESSURE".

[0018] like Figure 1As shown, the tire 1 of this embodiment includes a tread portion 2, a pair of sidewall portions 3 extending from both ends of the tread portion 2 inward in the tire radial direction, and a pair of bead portions 4 located inward in the tire radial direction of the sidewall portions 3. For example, bead cores 5 are embedded in each of the pair of bead portions 4.

[0019] The tread surface 2s, which is the outer surface of the tread portion 2, extends in a curved arc shape from the tire equator C to the tread end Te, convex outward in the radial direction of the tire. In this embodiment, the position of the tread end Te forms the position of the maximum tire width. Such a tire 1 can provide a large camber angle for cornering.

[0020] Here, the tread end Te is the axial end of the tread portion 2. The tire equator C is the axial center between the tread ends Te. Furthermore, the length measured along the tread surface 2s between the tread ends Te is the tread width TWe.

[0021] The tire 1 of this embodiment includes a tire body 6 extending from the tread portion 2 through a pair of sidewall portions 3 to a pair of bead portions 4. The tire body 6 includes, for example, a main body portion 6a spanning between a pair of bead cores 5 and a folded portion 6b connected to the main body portion 6a and folded back around the bead cores 5.

[0022] The tire carcass 6 comprises at least one, and in this embodiment, two tire carcass ply layers 6A and 6B. The tire carcass ply layers 6A and 6B each comprise, for example, tire carcass cords arranged at an angle of 75° to 90° relative to the tire circumference.

[0023] The tire 1 of this embodiment includes a tread reinforcement layer 7 located radially outward of the tire carcass 6 disposed in the tread portion 2. The tread reinforcement layer 7 of this embodiment includes a belt layer 8 and a crown belt layer 9.

[0024] Figure 2 This is a developed view of the tread reinforcement layer 7 in this embodiment. Figure 1 and Figure 2 As shown, the belt layer 8 is preferably composed of a plurality of belt cords 8a. The crown layer 9 is preferably composed of a plurality of crown cords 9a.

[0025] In this embodiment, the belt layer 8 is composed of an inner belt ply 8A disposed adjacent to the tire carcass 6 and an outer belt ply 8B disposed outside the inner belt ply 8A in the tire radial direction.

[0026] In this embodiment, the belt cords 8a of the inner belt ply 8A are arranged at a first angle θ1 greater than 5° relative to the tire circumference. In this embodiment, the belt cords 8a of the outer belt ply 8B are arranged at a second angle θ2 greater than 5° relative to the tire circumference. This belt ply 8, through the clamping effect of the inner belt ply 8A and the outer belt ply 8B, helps to improve the rigidity of the tread portion 2 and generates greater lateral resistance.

[0027] Here, the turning of the motorized two-wheeled vehicle is achieved by tilting the vehicle. At this time, the lateral force generated by tire 1 is expressed as the sum of the outward camber lateral force generated by the tilt of tire 1 and the lateral resistance force generated by the slip angle of tire 1. When the lateral force generated by tire 1 is balanced with the centrifugal force of the motorized two-wheeled vehicle, it can be said that the motorized two-wheeled vehicle can turn stably and has excellent turning performance.

[0028] The centrifugal force of a motorized two-wheeled vehicle is relatively small during a gentle turn, but larger during a sharp turn, starting from a straight-ahead state. Therefore, tire 1 can suppress the generation of lateral resistance when transitioning from a straight-ahead state to a gentle turn, and increase the lateral resistance during a sharp turn, thereby improving the turning performance when transitioning from a straight-ahead state to a sharp turn.

[0029] In this embodiment, the tire 1 can increase the lateral resistance through the belt layer 8, thus increasing the lateral force acting on the tire 1 and improving the cornering performance when the centrifugal force is large, such as in a sharp turn.

[0030] In this embodiment, the unfolded width W1 of the outer belt ply 8B is greater than the unfolded width W2 of the inner belt ply 8A. Such a belt ply 8 can suppress belt edge loosening, where the belt cords 8a peel off at the ends of the ply, thus improving durability. Here, the unfolded width of the ply is the length measured along the outer surface of the ply between the ends of the ply in the tire axial direction.

[0031] The crown belt layer 9 is composed of at least one crown belt ply 9A (in this embodiment, one sheet) formed by arranging crown belt cords 9a at an angle θ3 of 5° or less relative to the tire circumference. In this embodiment, the crown belt ply 9A is disposed adjacent to the inner belt ply 8A and the outer belt ply 8B in the tire radial direction between the inner belt ply 8A and the outer belt ply 8B.

[0032] Such a tire 1 can mitigate the clamping effect between the inner belt ply 8A and the outer belt ply 8B, and can suppress the generation of excessive lateral resistance when the centrifugal force is small, such as when transitioning from a straight driving state to a gentle turning state. Therefore, the tire 1 of this embodiment can balance cornering performance and durability.

[0033] As a more preferred embodiment, the second angle θ2 of the belt cord 8a of the outer belt ply 8B relative to the tire circumference is different from the first angle θ1 of the belt cord 8a of the inner belt ply 8A relative to the tire circumference. Such a belt ply 8 can more reliably exert the clamping effect of the inner belt ply 8A and the outer belt ply 8B.

[0034] In this embodiment, the second angle θ2 is larger than the first angle θ1. The angle of the belt cord 8a of the outer belt ply 8B near the tread surface 2s of such a belt layer 8 is larger relative to the tire circumference, thus improving the rigidity of the tread portion 2 and contributing to greater lateral resistance.

[0035] The difference (θ2-θ1) between the second angle θ2 and the first angle θ1 is preferably 10° to 40°. When the difference (θ2-θ1) is 10° or more, the hoop effect brought about by the inner banding fabric layer 8A and the outer banding fabric layer 8B can be utilized. When the difference (θ2-θ1) is 40° or less, the difference in lateral resistance caused by the presence or absence of the coronary banding fabric layer 9A can be reduced, and the transition characteristics at the boundary position of the coronary banding fabric layer 9A can be improved.

[0036] The first angle θ1 is preferably 50° to 80°. By making the first angle θ1 50° or higher, excessive hoop effect can be suppressed, good lateral resistance can be generated, and turning performance can be improved. By making the first angle θ1 80° or lower, an angle difference can be reliably set between the belt cords 8a of the outer belt cord layer 8B, and the hoop effect can be utilized.

[0037] The second angle θ2 is preferably 70° to 90°. By making the second angle θ2 70° or higher, excessive hoop effect can be suppressed, good lateral resistance can be generated, and turning performance can be improved. By making the second angle θ2 90° or lower, since the direction of inclination of the belt cord 8a of the inner belt cord layer 8A is the same, configuration errors during manufacturing can be reduced.

[0038] In this embodiment, the unfolded width W3 of the crown cord ply 9A is smaller than the unfolded width W2 of the inner belt cord ply 8A. This tread reinforcement layer 7 can mitigate the clamping effect between the inner belt cord ply 8A and the outer belt cord ply 8B during gentle cornering, starting from a straight-line driving state, and exerts a clamping effect during sharp cornering.

[0039] Therefore, the tire 1 of this embodiment can suppress the generation of excessive lateral resistance in a gentle turning state from a straight-going state, and generate large lateral resistance in a sharp turning state, thereby improving the turning performance from a straight-going state to a sharp turning state.

[0040] The unfolded width W3 of the crown belt ply 9A is preferably 30% to 90% of the tread unfolded width TWe. By making the unfolded width W3 of the crown belt ply 9A 30% or more of the tread unfolded width TWe, even if the tread portion 2 deforms during braking in a straight-line state, the crown belt ply 9A can be reliably contained in the contact patch, thereby reducing lateral resistance. From this point of view, the unfolded width W3 of the crown belt ply 9A is more preferably 35% or more of the tread unfolded width TWe, and even more preferably 40% or more.

[0041] By making the unfolded width W3 of the crown belt ply 9A less than 90% of the tread unfolded width TWe, the hoop effect during sharp turns can be reliably exerted, and the lateral resistance can be increased. From this point of view, the unfolded width W3 of the crown belt ply 9A is more preferably less than 85% of the tread unfolded width TWe, and even more preferably less than 80%.

[0042] The difference (W1-W2) between the unfolded width W1 of the outer belt ply 8B and the unfolded width W2 of the inner belt ply 8A is preferably 10 mm or more. That is, in this embodiment, the distance L1 between the tire axial end of the outer belt ply 8B and the tire axial end of the inner belt ply 8A is 5 mm or more on both sides of the tire axial direction. Such a belt ply 8 can more reliably suppress the occurrence of belt edge peeling and improve durability.

[0043] Figure 3 This is an enlarged cross-sectional view of the tread portion 2 in this embodiment. (See attached image.) Figures 1 to 3 As shown, the tread portion 2 of this embodiment includes a rubber layer 10 disposed on the outer side of the crown cord ply 9A in the tire axial direction. The rubber layer 10 is preferably disposed on both sides of the crown cord ply 9A in the tire axial direction. Each rubber layer 10 is composed of at least one (in this embodiment, one) rubber sheet 10A.

[0044] Here, the state including the rubber layer 10 composed of rubber sheet 10A indicates that the distance between the components disposed between the rubber layer 10 and the rubber layer 10 remains approximately constant. Furthermore, in this specification, "approximately constant distance" means that the deviation from the average value of this distance is within ±15%.

[0045] The torsional stiffness of the tread 2 is improved by the rubber sheet 10A, which increases the lateral resistance during sharp turns. Therefore, the tire 1 of this embodiment can improve the cornering performance during sharp turns. In addition, when the rubber layer 10 is composed of a plurality of rubber sheets 10A, each rubber sheet 10A can be arranged along the radial direction of the tire, and each rubber sheet 10A can also be arranged along the axial direction of the tire.

[0046] In this embodiment, the rubber layer 10 is disposed between the inner belted fabric layer 8A and the outer belted fabric layer 8B. The distance t between the inner belted fabric layer 8A and the outer belted fabric layer 8B at the location where the rubber layer 10 is disposed is preferably 0.5 mm to 3.0 mm and is approximately constant. Here, the distance t between the inner belted fabric layer 8A and the outer belted fabric layer 8B is the shortest distance between the outer surface 8As of the inner belted fabric layer 8A and the inner surface 8Bs of the outer belted fabric layer 8B.

[0047] By setting the distance t to 0.5 mm or more, the torsional effect can be reliably achieved, and the lateral resistance during sharp turns can be increased. By setting the distance t to 3.0 mm or less, excessive increase in lateral resistance can be prevented, and the transition characteristics with the area having the crown cord fabric layer 9A can be improved.

[0048] In this embodiment, the sum of the unfolded width W4 of the rubber layers 10 on both sides and the unfolded width W3 of the crown cord layer 9A (W3+2×W4) is smaller than the unfolded width W2 of the inner belt cord layer 8A. Such rubber layers 10 can further improve the torsional stiffness of the tread portion 2.

[0049] The complex elastic modulus G* of the rubber layer 10 at 70°C is preferably 500 kPa or higher. Such a rubber layer 10 can more reliably exert torsional effects and further increase lateral resistance during sharp turns.

[0050] Here, the complex elastic modulus G* of rubber layer 10 at 70°C is the value measured using a dynamic viscoelasticity measuring device (Iplexer series) manufactured by GABO under the following conditions, according to JIS-K6394.

[0051] Initial strain: 10%

[0052] Amplitude of dynamic strain: ±1%

[0053] Frequency: 10Hz

[0054] Deformation mode: Stretch

[0055] Measurement temperature: 70℃

[0056] The preferred embodiments of this disclosure have been described in detail above, but this disclosure is not limited to the above embodiments and can be implemented in various ways.

[0057] [Example]

[0058] Based on the specifications in Table 1, a prototype with... Figure 1A basic structure for a motorized two-wheeled vehicle tire was developed. As Comparative Example 1, a motorized two-wheeled vehicle tire with a crown belt layer positioned outside the belt layer in the radial direction was prototyped. The prototype tire was mounted on the front and rear wheels of a test motorized two-wheeled vehicle to test cornering performance, and the durability performance was tested using a prototype tire for the rear wheels. The main commonalities and test methods are as follows.

[0059] <Common Matters>

[0060] Front tire size: 120 / 70R17

[0061] Front tire pressure: 250 kPa

[0062] Rear tire size: 200 / 60R17

[0063] Rear tire pressure: 290 kPa

[0064] Experimental motorized two-wheeler: Large motorized two-wheeler

[0065] Cornering performance

[0066] Using a test two-wheeled motorized vehicle equipped with prototype tires, the driver's sensory evaluation was conducted to assess the smooth cornering performance from an upright position to a gentle turn, the sharp cornering performance from a sharp turn, and the transition characteristics from a gentle turn to a sharp turn. The results were expressed using an index of 100 (Comparative Example 1), with higher values ​​indicating better smooth cornering performance, sharp cornering performance, and transition characteristics. The sum of smooth cornering performance, sharp cornering performance, and transition characteristics was expressed as cornering performance.

[0067] <Durability>

[0068] The prototype tires for the rear wheels were mounted on a rotary drum testing machine. Under conditions of a load of 5.5 kN, a speed of 80 km / h, and a camber angle of 0°, it was determined whether belt edge peeling occurred after 7000 km of driving. The results showed that tires exhibiting belt edge peeling were "unqualified," while tires without belt edge peeling were "qualified." Qualified tires indicate excellent durability.

[0069] The test results are shown in Table 1.

[0070] [Table 1]

[0071]

[0072] The test results confirmed that the tires of the embodiment improved cornering performance compared to the comparative example, and also had excellent durability, thus achieving a balance between cornering performance and durability.

[0073] [Postscript]

[0074] This disclosure is as follows.

[0075] [This disclosure 1]

[0076] A tire for a motorized two-wheeled vehicle, comprising: a carcass extending from the tread portion through a pair of sidewall portions to a pair of bead portions; and a tread reinforcement layer disposed on the outer side of the carcass in the tread portion in the tire radial direction, the tread reinforcement layer comprising a belt layer with a plurality of belt cords arranged thereon and a crown belt layer with a plurality of crown cords arranged thereon, the belt layer consisting of an inner belt cord layer disposed adjacent to the carcass and an outer belt cord layer disposed on the outer side of the inner belt cord layer in the tire radial direction, the crown belt layer consisting of a belt cord layer disposed on the outer side of the inner belt cord layer in the tire radial direction. The inner belt ply and the outer belt ply are disposed adjacently between at least one crown belt ply. The belt cords of the inner belt ply are arranged at a first angle greater than 5° relative to the tire circumference, the belt cords of the outer belt ply are arranged at a second angle greater than 5° relative to the tire circumference, and the crown belt cords of the crown belt ply are arranged at an angle less than 5° relative to the tire circumference. The unfolded width of the outer belt ply is greater than the unfolded width of the inner belt ply.

[0077] [This disclosure 2]

[0078] According to the tire for motorized two-wheeled vehicles described in this disclosure 1, wherein...

[0079] The difference between the unfolded width of the outer belted fabric layer and the unfolded width of the inner belted fabric layer is more than 10 mm.

[0080] [This disclosure 3]

[0081] According to the tire for motorized two-wheeled vehicles described in disclosure 1 or 2, wherein...

[0082] The unfolded width of the crown belt fabric layer is smaller than the unfolded width of the inner belt fabric layer.

[0083] [This disclosure 4]

[0084] The motorized two-wheeled vehicle tire according to any one of disclosures 1 to 3, wherein...

[0085] The unfolded width of the crown belt ply is 30% to 90% of the unfolded width of the tread.

[0086] [This disclosure 5]

[0087] The motorized two-wheeled vehicle tire according to any one of disclosures 1 to 4, wherein...

[0088] The second angle is different from the first angle.

[0089] [This disclosure 6]

[0090] According to the tire for motorized two-wheeled vehicles described in this disclosure 5, wherein...

[0091] The second angle is larger than the first angle.

[0092] [This disclosure 7]

[0093] According to the tire for motorized two-wheeled vehicles described in this disclosure 6, wherein...

[0094] The difference between the second angle and the first angle is 10° to 40°.

[0095] [This disclosure is 8]

[0096] According to the tire for motorized two-wheeled vehicles described in this disclosure 7, wherein...

[0097] The first angle is 50° to 80°, and the second angle is 70° to 90°.

[0098] [This disclosure is number 9]

[0099] The motorized two-wheeled vehicle tire according to any one of disclosures 1 to 8, wherein...

[0100] The tread portion includes a rubber layer disposed on the outer side of the crown belt ply along the tire axial direction. The rubber layer is disposed between the inner belt ply and the outer belt ply. The distance between the inner belt ply and the outer belt ply at the location where the rubber layer is disposed is 0.5 mm to 3.0 mm and is approximately constant.

[0101] [This disclosure is number 10]

[0102] According to the tire for motorized two-wheeled vehicles described in this disclosure 9, wherein...

[0103] The rubber layer has a complex elastic modulus of over 500 kPa at 70°C.

Claims

1. A tire for a motorized two-wheeled vehicle, wherein, The tires for this motorized two-wheeled vehicle include: Fetal face; A pair of tire sidewalls; A pair of bead portions, each having a bead core; The tire carcass extends between the bead cores; and A tread reinforcement layer disposed on the outer side of the tire carcass in the tire tread portion in the tire radial direction. The tread reinforcement layer includes a belt layer and a crown belt layer with multiple crown belt cords arranged in a row. The belt layer consists of only two parts: an inner belt ply disposed adjacent to the tire carcass and an outer belt ply disposed outside the inner belt ply in the tire radial direction. The crown belt layer is composed of at least one crown belt ply disposed adjacent to the inner belt ply and the outer belt ply in the tire radial direction between the inner belt ply and the outer belt ply, and the crown belt cords of the crown belt ply are arranged at an angle of less than 5° relative to the tire circumference, thereby mitigating the hooping effect of the inner belt ply and the outer belt ply. The inner belt ply has a first unfolded width and has a plurality of belt cords arranged at a first angle greater than 5° relative to the tire circumference. The outer belt ply has a second spread width and a plurality of belt cords arranged at a second angle greater than 5° relative to the tire circumference. The second angle is larger than the first angle, and the difference between the second angle and the first angle is 10° to 40°. The second unfolded width is larger than the first unfolded width. The tread portion includes rubber layers disposed on both sides of the tire axial direction of the crown belt ply. In the radial direction of the tire, the rubber layer is disposed between the inner belt ply and the outer belt ply. The distance between the inner belted fabric layer and the outer belted fabric layer at the location where the rubber layer is located is 0.5 mm to 3.0 mm and remains approximately constant. The sum of the unfolded width of the rubber layer disposed on both sides of the tire axial direction of the crown belt ply and the unfolded width of the crown belt ply is smaller than the first unfolded width of the inner belt ply.

2. The tire for motorized two-wheeled vehicles according to claim 1, wherein, The difference between the second unfolded width and the first unfolded width is 10 mm or more.

3. The tire for motorized two-wheeled vehicles according to claim 1, wherein, The crown cord ply has a third spread width of 30% to 90% of the tread spread width.

4. The tire for motorized two-wheeled vehicles according to claim 1, wherein, The first angle is 50° to 80°. The second angle is 70° to 90°.

5. The tire for motorized two-wheeled vehicles according to claim 1, wherein, The rubber layer has a complex elastic modulus of over 500 kPa at 70°C.

Images