Tire for a two-wheeled motor vehicle

Abstract

The present invention provides a tire for a two-wheeled motor vehicle, which exhibits excellent handling stability during high-speed cornering. The tire (1) for a two-wheeled motor vehicle includes a carcass (6), a belt layer (7), and a chafer ply (8). The chafer ply (8) is a seamless chafer cord ply (8A). The belt cords (13) of the belt layer (7) cross the carcass cords (10) at a crossing angle (θc) in the tread crown region (Cr) and cross the carcass cords (10) at a crossing angle (θs) in the tread shoulder region (Sh). The crossing angle (θc) is larger than the crossing angle (θs).

Description

Technical Field

[0001] The present invention relates to a tire for a two-wheeled motor vehicle. Background Art

[0002] In Patent Document 1 below, a tire for a two-wheeled motor vehicle is described in which a carcass layer, a belt layer, and a belt reinforcing layer are disposed on the tread surface. In the tire for a two-wheeled motor vehicle, the cord angles of the cord forming the carcass layer, the cord forming the belt layer, and the organic fiber cord forming the belt reinforcing layer are specified. Thus, the tire for a two-wheeled motor vehicle of Patent Document 1 has excellent handling stability during turning.

[0003] Patent Document 1: Japanese Patent No. 5179803

[0004] In recent years, it has been desired to further improve the handling stability during turning, particularly during high-speed turning at a speed of 70 km / h or more. Summary of the Invention

[0005] The present invention has been made in view of the above actual situation, and its main object is to provide a tire for a two-wheeled motor vehicle that can improve the handling stability during turning, particularly during high-speed turning.

[0006] The present invention is a tire for a two-wheeled motor vehicle, which includes: a tread surface; a pair of sidewall portions; a pair of bead portions; a ring-shaped carcass extending between the pair of bead portions; and a belt layer and a chafer layer, the belt layer and the chafer layer being disposed outside the carcass in the tire radial direction and inside the tread surface, the carcass including a plurality of carcass cords, the chafer layer being a seamless chafer cord fabric layer including chafer cords spirally arranged at an angle of 5° or less with respect to the tire circumferential direction, the belt layer including a plurality of belt cords arranged in a direction crossing the carcass cords, the belt cords crossing the carcass cords at a crossing angle θc in the tread crown region and crossing the carcass cords at a crossing angle θs in the tread shoulder region, and the crossing angle θc being larger than the crossing angle θs.

[0007] In the tire for a two-wheeled motor vehicle of the present invention, it is preferable that the chafer layer is disposed at a position closer to the inner side in the tire radial direction than the belt layer.

[0008] In the tire for a two-wheeled motor vehicle of the present invention, it is preferable that the width of the chafer layer in the tire axial direction is 0.5 times to 0.9 times the width of the belt layer in the tire axial direction.

[0009] In the tire for a two-wheeled motor vehicle of the present invention, it is preferable that the crossing angle θc and the crossing angle θs are in the range of 20 degrees to 65 degrees.

[0010] In the motorcycle tire of the present invention, it is preferable that the angle of the belt cord with respect to the tire circumferential direction is 85 degrees or more.

[0011] In the motorcycle tire of the present invention, it is preferable that the outer end of the belt layer in the tire axial direction is located at a position of 70% to 100% of the half width of the tread width from the tire equator.

[0012] In the motorcycle tire of the present invention, it is preferable that the angle of the carcass cord with respect to the tire circumferential direction is 25 degrees to 70 degrees.

[0013] In the motorcycle tire of the present invention, it is preferable that the tread shoulder region has a width of 30% or more of the half width of the tread width from the tread end toward the inner side in the tire axial direction.

[0014] By adopting the above structure, the motorcycle tire of the present invention can exhibit excellent handling stability during high-speed cornering. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a cross-sectional view showing an embodiment of the motorcycle tire of the present invention.

[0016] Figure 2 is Figure 1 an expanded view of the inside of the tread portion of

[0017] REFERENCE SIGNS

[0018] 1: Motorcycle tire; 6: Carcass; 7: Belt layer; 8: Crown ply; 8A: Seamless crown ply cord fabric layer; 10: Carcass cord; 13: Belt cord; Cr: Tread crown region; Sh: Tread shoulder region. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described based on the drawings.

[0020] Figure 1 is a tire meridian cross-sectional view in a normal state of the motorcycle tire 1 (hereinafter, sometimes simply referred to as "tire") of the present embodiment including the tire rotation axis (not shown). The tire 1 of the present embodiment is suitable for road driving on a dry asphalt road surface or the like, for example. However, the tire 1 of the present invention is not limited to such a mode.

[0021] The above "normal state" means a non-loaded state in which the tire 1 is assembled to a normal rim (not shown) and filled with a normal internal pressure. Unless otherwise specified, the dimensions and the like of each part of the tire are values measured in the normal state.

[0022] "Normal rim" refers to the rim determined for each tire in a specification system including the specifications on which Tire 1 is based. For example, if it is JATMA, it is the standard rim; if it is TRA, it is the "Design Rim"; if it is ETRTO, it is the "Measuring Rim".

[0023] "Normal internal pressure" refers to the air pressure determined for each tire in a specification system including the specifications on which Tire 1 is based. If it is JATMA, it is the maximum air pressure; if it is TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; if it is ETRTO, it is the "INFLATION PRESSURE".

[0024] As Figure 1 shown, the tire 1 of the present embodiment includes a tread portion 2, a pair of sidewall portions 3, and a pair of bead portions 4. For example, in the tire meridian cross-section, the outer surface 2a of the tread portion 2 is curved into an arc shape protruding outward in the tire radius direction.

[0025] In the present embodiment, the tread portion 2 includes: a tread crown region Cr, which includes the tire equator C; and a tread shoulder region Sh, which is disposed on both sides of the tread crown region Cr. The tread crown region Cr extends, for example, on both sides of the tire equator C in the tire axial direction. The tread shoulder region Sh has a width Ws of 30% or more of the half width Bw of the tread spread from the tread end Te toward the inside in the tire axial direction. The width Ws of the tread shoulder region Sh is, for example, 40% or less of the half width Bw of the tread spread from the tread end Te toward the inside in the tire axial direction. The "half width Bw of the tread spread" refers to a length that is 0.5 times the length in the tire axial direction between the tread ends Te, Te when the tread portion 2 is flattened.

[0026] A pair of sidewall portions 3 are connected to both ends in the tire axial direction of the tread portion 2 and extend toward the inside in the tire radius direction. A pair of bead portions 4 are respectively connected to the sidewall portions 3, for example, and extend toward the inside in the tire radius direction. A bead core 5 is embedded in each bead portion 4.

[0027] The tire 1 of the present embodiment includes: an annular carcass 6, which extends between a pair of bead portions 4; and a belt layer 7 and a chafer layer 8, which are disposed outside the carcass 6 in the tire radius direction and inside the tread portion 2.

[0028] Figure 2 is an expanded view of the inside of the tread portion 2. As Figure 2As shown, the carcass 6 includes a plurality of carcass cords 10. In addition, the belt layer 8 is a seamless belt ply 8A including belt cords 11 spirally arranged at an angle θa of 5° or less with respect to the tire circumferential direction. Such a belt layer 8 suppresses the growth of the tire outer diameter and improves the high-speed stability performance during straight running. The belt layer 7 includes a plurality of belt cords 13 arranged in a direction intersecting the carcass cords 10.

[0029] In addition, the belt cords 13 intersect the carcass cords 10 at an intersection angle θc in the tread crown region Cr and intersect the carcass cords 10 at an intersection angle θs in the tread shoulder region Sh. The intersection angle θc is larger than the intersection angle θs. Thus, in the tread shoulder region Sh, the shear rigidity is increased, a large hoop effect is exerted, and thus a large centrifugal force can be borne. Therefore, the tire 1 of the present embodiment exhibits excellent handling stability performance during high-speed cornering. In addition, in the tread crown region Cr, the intersection angle θc becomes relatively large, so the shear rigidity does not become too high, and the riding comfort performance and the high-speed stability performance during straight running can be maintained.

[0030] The intersection angle θc and the intersection angle θs are preferably in the range of 20 degrees to 65 degrees. Since the intersection angle θc and the intersection angle θs are 65 degrees or less, a hoop effect can be obtained, and thus the stability performance during straight running and cornering can be ensured. When the intersection angle θc and the intersection angle θs are less than 20 degrees, the hoop effect is not exerted. From this point of view, the intersection angle θc and the intersection angle θs are more preferably 25 degrees or more, further preferably 30 degrees or more, more preferably 60 degrees or less, and further preferably 55 degrees or less.

[0031] The difference (θc - θs) between the intersection angle θc and the intersection angle θs is preferably 3 degrees to 20 degrees. Since the difference (θc - θs) is 3 degrees or more, the stability performance during straight running and cornering can be improved. Since the difference (θc - θs) is 20 degrees or less, the difference in shear rigidity between the tread crown region Cr and the tread shoulder region Sh becomes smaller, and the steering wheel operation from straight running to cornering and the steering wheel operation from cornering to straight running become smooth, and the stability performance is improved. Therefore, the difference (θc - θs) is more preferably 5 degrees or more and more preferably 15 degrees or less.

[0032] In the present embodiment, the intersection angle θc is the angle on the tire equator C. In addition, the intersection angle θs is the position P that is 30% of the half width Bw of the tread developed toward the inner side in the tire axial direction from the tread end Te. Further, in the case where the carcass 6 or the belt layer 7 is composed of a plurality of plies, the intersection angles θc and θs are determined by the cords of the ply of the carcass 6 arranged on the outermost side in the tire radial direction and the cords of the ply of the belt layer 7 arranged on the innermost side in the tire radial direction.

[0033] The carcass 6 is formed, for example, to include at least one carcass ply obtained by covering carcass cords 10 with coated rubber. In the present embodiment, the carcass 6 is formed of two carcass plies 6A and 6B overlapping each other inside and outside in the tire radial direction. Each of the carcass plies 6A and 6B extends, for example, in a manner spanning between the two bead cores 5, 5 ( Figure 1 as shown).

[0034] In the present embodiment, the inner carcass ply 6A and the outer carcass ply 6B are arranged in such a manner that the carcass cords 10 cross each other inside and outside in the tire radial direction. Each of the carcass cords 10 is formed of, for example, organic fiber cords.

[0035] The angle θ1 of the carcass cords 10 of the present embodiment with respect to the tire circumferential direction increases from the tire equator C toward the tread ends Te on both sides. Such carcass cords 10 increase the rigidity in the tire axial direction at the tread ends Te side and increase the rigidity in the tire circumferential direction at the tire equator C side. The angle θ1 of the carcass cords 10 gradually increases, for example, from the tire equator C toward the tread ends Te on both sides.

[0036] The angle θ1a of the carcass cords 10 with respect to the tire circumferential direction is preferably, for example, 25 degrees to 70 degrees. Since the angle θ1a is 25 degrees or more and 70 degrees or less, an effective hoop effect can also be exerted in the two carcass plies 6A and 6B. Therefore, the angle θ1a is more preferably 30 degrees or more and more preferably 65 degrees or less. The angle θ1a is the angle on the tread crown region Cr, and more specifically, on the tire equator C.

[0037] In addition, the angle θ1b of the carcass cords 10 with respect to the tire circumferential direction at the tread shoulder region Sh, and more specifically, at the position P is preferably 35 degrees or more, further preferably 40 degrees or more, preferably 80 degrees or less, and further preferably 75 degrees or less. Thereby, the above-described effects are effectively exerted.

[0038] As Figure 1 shown, the outer end 8e in the tire axial direction of the belt layer 8 is located, for example, at a position closer to the inner side in the tire axial direction than the outer end 7e in the tire axial direction of the belt layer 7. In addition, the belt layer 8 of the present embodiment is arranged at a position closer to the inner side in the tire radial direction than the belt layer 7. In other words, the belt layer 8 is sandwiched between the carcass 6 and the belt layer 7 in the present embodiment. Thereby, when the camber angle changes, the impact transmitted to the vehicle's steering wheel when the outer end 8e in the tire axial direction of the belt layer 8 contacts the ground can be absorbed by the belt layer 7. Thereby, the handling stability during high-speed cornering is further improved.

[0039] The axial width Wb of the crown belt layer 8 is preferably 0.5 to 0.9 times the axial width Wa of the belt layer 7. Since the width Wb of the crown belt layer 8 is more than 0.5 times the width Wa of the belt layer 7, the high-speed stability performance during straight running is improved. Since the width Wb of the crown belt layer 8 is less than 0.9 times the width Wa of the belt layer 7, the handling stability performance during high-speed cornering is improved.

[0040] In order to effectively exert the above effects, the outer end 7e in the tire axial direction of the belt layer 7 is preferably located at a position 70% to 100% of the half-width Bw of the tread development along the outer surface 2a of the tread surface 2 from the tire equator C.

[0041] As Figure 2 shown, the belt cords 13 of the belt layer 7 extend linearly in the present embodiment. The angle θ2 of the belt cords 13 with respect to the tire circumferential direction may also gradually increase from the tire equator C toward the tread end Te side, for example. The angle θ2 of the belt cords 13 with respect to the tire circumferential direction is preferably 85 degrees or more. Thereby, the rigidity in the tire axial direction of the tire 1 can be increased. The angle θ2 of the belt cords 13 is more preferably 88 degrees or more, and further preferably 90 degrees.

[0042] The above has described in detail a motorcycle tire according to an embodiment of the present invention. However, the present invention is not limited to the above specific embodiment and can be implemented in various modified forms.

[0043] [Examples]

[0044] A motorcycle tire having the Figure 1 basic structure was trial-produced. And the handling stability performance during high-speed cornering, the handling stability performance during low-speed running (less than 70 km / h) and the high-speed stability performance during straight running of each test tire were tested. The common specifications and test methods of each test tire are as follows.

[0045] <Handling stability performance during high-speed cornering, handling stability performance during low-speed running, and high-speed stability performance during straight running>

[0046] The test driver drove a test vehicle equipped with a test tire on a test route on a dry asphalt road surface. After driving, the test driver evaluated each test item by sensory evaluation. The evaluation was performed by a 10-point method with a full score of 10. The larger the value, the better each test item. In addition, the "position of 7e" in Table 1 refers to the tread development length between the outer end in the tire axial direction of the belt layer and the tire equator / half-width of the tread development.

[0047] Front-wheel tire (size, rim, internal pressure): 110 / 70-13M / C, 13×3.00MT, 200 kPa

[0048] Tire for rear wheel (size, rim, internal pressure): 130 / 70-13M / C, 13×3.50MT, 220 kPa

[0049] Test vehicle: Motorized two-wheeler with a displacement of 1000 cc

[0050] The test results are shown in Table 1 below.

[0051] [Table 1]

[0052]

[0053] It was confirmed from the test results that the tires of the examples exhibited excellent handling stability during high-speed cornering. In addition, it was also confirmed that the handling stability of the tires of the examples during low-speed driving and the high-speed stability during straight-line driving were also improved.

Claims

1. A tire for a motorized two-wheeler, comprising: A tread surface portion; A pair of sidewall portions; A pair of bead portions; An annular carcass extending between the pair of bead portions; and A belt layer and a chafer layer, the belt layer and the chafer layer being disposed outside the carcass in the tire radial direction and inside the tread surface portion, The carcass includes a plurality of carcass cords, The chafer layer is a seamless chafer ply, the seamless chafer ply including chafer cords spirally arranged at an angle of 5° or less with respect to the tire circumferential direction, The belt layer includes a plurality of belt cords arranged in a direction intersecting the carcass cords, The belt cords intersect the carcass cords at an intersection angle θc in the tread crown region and intersect the carcass cords at an intersection angle θs in the tread shoulder region, The intersection angle θc is larger than the intersection angle θs, The angle θ1 of the carcass cords with respect to the tire circumferential direction gradually increases from the tire equator toward the tread ends on both sides.

2. The tire for a motorized two-wheeler according to claim 1, wherein The chafer layer is disposed at a position radially inward of the belt layer.

3. The tire for a motorized two-wheeler according to claim 1 or 2, wherein The axial width of the chafer layer in the tire axial direction is 0.5 to 0.9 times the axial width of the belt layer in the tire axial direction.

4. The tire for a motorized two-wheeler according to claim 1 or 2, wherein The intersection angle θc and the intersection angle θs are in the range of 20 degrees to 65 degrees.

5. The tire for a motorized two-wheeler according to claim 1 or 2, wherein The angle of the belt cords with respect to the tire circumferential direction is 85 degrees or more.

6. The tire for a motorized two-wheeler according to claim 1 or 2, wherein The outer ends of the belt layer in the tire axial direction are located at positions along the outer surface of the tread surface portion at 70% to 100% of half the width of the tread development from the tire equator.

7. The tire for a motorized two-wheeler according to claim 1 or 2, wherein The angle of the carcass cords with respect to the tire circumferential direction is 25 degrees to 70 degrees.

8. The tire for a motorized two-wheeler according to claim 1 or 2, wherein The tread shoulder region has a width of 30% or more of half the width of the tread development from the tread end along the outer surface of the tread surface portion toward the inner side in the tire axial direction.

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