Motorcycle tires

Abstract

To provide a two-wheeled motor vehicle tire where straight line stability at high-speed traveling is compatible with turning performance.SOLUTION: A two-wheeled motor vehicle tire 1 includes a tread reinforcement layer 7. The tread reinforcement layer 7 includes a belt layer 8 and a band layer 9. The band layer 9 includes a band ply 9A where band codes 9A are arrayed at an angle θ1 relative to a tire circumferential direction. The belt layer 8 includes: an inner side belt ply 8A which is arranged so as not to overlap with the band ply 9A at both sides of the band ply 9A in a tire axial direction; and an outer side belt ply 8B which is arranged so as to overlap with the band ply 9A outside of the band ply 9A in a tire radial direction. The inner side belt ply 8A includes an inner side belt cord 8a which is arrayed at an angle θ2 different from the angle θ1 relative to the tire circumferential direction, and the outer side belt ply 8B includes an outer side belt cord 8b which is arrayed at an angle θ3 different from the angle θ1 and the angle θ2 relative to the tire circumferential direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a tire for a motorcycle.

Background Art

[0002] Conventionally, a motorcycle tire including a tread reinforcing layer in a tread portion is known. For example, Patent Document 1 below proposes a motorcycle tire in which the tread reinforcing layer is composed of two belt plies arranged on the outer side in the tire radial direction of the carcass and one band ply arranged on the outer side in the tire radial direction of the two belt plies.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, even in the motorcycle tire of Patent Document 1, further improvement has been desired for achieving both straight-line stability and turning performance during high-speed driving.

[0005] The present disclosure has been devised in view of the above actual situation, and the main object thereof is to provide a motorcycle tire capable of achieving both straight-line stability and turning performance during high-speed driving.

Means for Solving the Problems

[0006] This disclosure relates to a motorcycle tire comprising a carcass extending from a tread portion through a pair of sidewall portions to a pair of bead portions, and a tread reinforcing layer disposed on the radially outside of the carcass in the tread portion, wherein the tread reinforcing layer comprises a belt layer and a band layer, the band layer comprises at least one band ply with band cords arranged at an angle of 5° or less with respect to the circumferential direction of the tire, the belt layer comprises a pair of inner belt plies disposed on both sides of the band ply in the axial direction of the tire without overlapping the band ply, and at least one outer belt ply disposed on the radially outside of the band ply so as to overlap the band ply, the inner belt ply has inner belt cords arranged at an angle different from the angle of the band cords with respect to the circumferential direction of the tire, and the outer belt ply has outer belt cords arranged at an angle different from the angle of the band cords and the angle of the inner belt cords with respect to the circumferential direction of the tire. [Effects of the Invention]

[0007] The motorcycle tire of this disclosure, by having the above-described configuration, can achieve both straight-line stability and cornering performance at high speeds. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view showing one embodiment of a motorcycle tire according to the present disclosure. [Figure 2] This is a schematic diagram showing the deployment of the tread reinforcement layer. [Modes for carrying out the invention]

[0009] One form of implementation of this disclosure will be described in detail below with reference to the drawings. Figure 1 is a meridian cross-sectional view of the motorcycle tire 1 (hereinafter sometimes simply referred to as "tire 1") of this embodiment in its normal state.

[0010] Here, "normal condition" refers to a state in which tire 1 is mounted on a normal rim, adjusted to the normal internal pressure, and under no load. Unless otherwise specified in this specification, the dimensions of each part of tire 1 are values ​​measured under the normal condition.

[0011] Furthermore, a "standard rim" is the rim defined for each tire within the standard system that includes the standard on which the tire is based. For example, it is a "standard rim" for JATMA, a "design rim" for TRA, and a "measuring rim" for ETRTO.

[0012] Furthermore, "standard internal pressure" refers to the air pressure specified for each tire by each standard within the standards system, including the standard on which the tire is based. For JATMA, this is the "maximum air pressure," for TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and for ETRTO, it is the "INFLATION PRESSURE."

[0013] As shown in Figure 1, the tire 1 of this embodiment includes a tread portion 2, a pair of sidewall portions 3 extending radially inward from both ends of the tread portion 2, and a pair of bead portions 4 located radially inward of the sidewall portions 3. Each of the pair of bead portions 4 is, for example, provided with a bead core 5.

[0014] The tread surface 2s, which is the outer surface of the tread portion 2, extends in a curved arc shape that is convex outward in the radial direction of the tire, for example, from the tire equator C to the tread edge Te. In this embodiment, the position of the tread edge Te is the position of the tire's maximum width. Such a tire 1 can be given a large camber angle for turning.

[0015] Here, the tread edge Te is the axial end of the tread section 2. The tire equator C is the axial center between the tread edges Te. The length measured along the tread surface 2s between the tread edges Te is the tread width TWe.

[0016] The tire 1 of this embodiment includes a carcass 6 that extends from the tread portion 2 through a pair of sidewall portions 3 to a pair of bead portions 4. The carcass 6 includes, for example, a main portion 6a that spans between a pair of bead cores 5 and a folded portion 6b that is connected to the main portion 6a and folded back around the bead cores 5. Preferably, the tire 1 includes a tread reinforcing layer 7 disposed on the radially outer side of the carcass 6 in the tread portion 2.

[0017] The carcass 6 includes at least one carcass ply 6A, 6B arranged with carcass cords, and in this embodiment, two carcass plies 6A, 6B. The carcass plies 6A, 6B include, for example, an inner carcass ply 6A positioned on the inside in the tire radial direction in the tread portion 2, and an outer carcass ply 6B positioned on the outside in the tire radial direction of the inner carcass ply 6A.

[0018] Figure 2 is a schematic diagram of the unfolded tread reinforcement layer 7. As shown in Figures 1 and 2, the tread reinforcement layer 7 of this embodiment includes a belt layer 8 and a band layer 9. The band layer 9 includes at least one band ply 9A in this embodiment, in which band cords 9a are arranged at an angle θ1 of 5° or less with respect to the circumferential direction of the tire. Hereinin this specification, the cord angle is measured as an angle perpendicular or less with respect to the circumferential direction of the tire.

[0019] The belt layer 8 includes a pair of inner belt plies 8A arranged on both sides of the band ply 9A in the tire axial direction, and at least one outer belt ply 8B, in this embodiment one, arranged on the outside of the band ply 9A in the tire radial direction. Preferably, the inner belt plies 8A are arranged so as not to overlap the band plies 9A. Preferably, the outer belt plies 8B are arranged so as to overlap the band plies 9A.

[0020] The inner belt ply 8A of this embodiment has inner belt cords 8a arranged at an angle θ2 different from the angle θ1 of the band cords 9a with respect to the tire circumferential direction. The outer belt ply 8B preferably has outer belt cords 8b arranged at an angle θ3 different from the angle θ1 of the band cords 9a and the angle θ2 of the inner belt cords 8a with respect to the tire circumferential direction.

[0021] By having the band ply 9A in the region that contacts the ground during straight running, such a tread reinforcing layer 7 can suppress the growth of the outer diameter during high-speed running and improve the straight running stability of the tire 1 during high-speed running. Also, by having the inner belt ply 8A in the region that contacts the ground during a sharp turn, this tread reinforcing layer can increase the cornering force during a sharp turn and improve the turning performance of the tire 1 during a sharp turn.

[0022] Moreover, since the outer belt ply 8B having the outer belt cords 8b arranged at an angle θ3 different from the band ply 9A and the inner belt ply 8A is arranged on the outer side in the tire radial direction, the tread reinforcing layer 7 can improve the transient characteristics during turning. Therefore, the tire 1 of this embodiment can achieve both straight running stability and turning performance during high-speed running.

[0023] As a more preferable aspect, the angle θ3 of the outer belt cords 8b with respect to the tire circumferential direction is larger than the angle θ2 of the inner belt cords 8a with respect to the tire circumferential direction. Such a tread reinforcing layer 7 can suppress the shear force acting on the tread surface 2s during turning and improve the turning performance of the tire 1. Also, this tread reinforcing layer 7 can adjust the turning force of the tire 1 by changing the angle difference between the angle θ3 of the outer belt cords 8b and the angle θ2 of the inner belt cords 8a.

[0024] The angle θ3 of the outer belt cord 8b with respect to the tire circumferential direction is preferably 70 to 90°. An angle θ3 of 70° or greater for the outer belt cord 8b suppresses the shear force acting on the tread surface 2s during cornering and also suppresses the change in stiffness between the band ply 9A and the inner belt ply 8A, thereby further improving the cornering performance of the tire 1. From this viewpoint, the angle θ3 of the outer belt cord 8b is more preferably 80° or greater, and even more preferably 85° or greater.

[0025] Although not shown in the diagram, the outer belt ply 8B may be arranged symmetrically with respect to the tire equator C, for example, if the angle θ3 of the outer belt cord 8b is 85° or more. Such a tread reinforcement layer 7 has excellent balance performance between left and right turns, and can further improve the turning performance of the tire 1.

[0026] In this case, the outer belt cords 8b may be arranged in a V-shape around the tire equator C, or in a V-shape. The outer belt cords 8b may also be arranged in an arc shape around the tire equator C, in which case it is desirable that the maximum angle θ3 of the outer belt cords 8b is 85° or more.

[0027] The angle θ2 of the inner belt cord 8a with respect to the tire circumferential direction is preferably 20 to 50°. Such an inner belt ply 8A can exert a hoop effect with the outer belt ply 8B, promoting rubber deformation on the tread surface 2s and helping to increase cornering force. For this reason, the tread reinforcement layer 7 of this embodiment can improve the turning performance of the tire 1 during sharp turns.

[0028] In this embodiment, the outer belt cord 8b and the inner belt cord 8a are inclined in opposite directions with respect to the tire circumferential direction. Such a tread reinforcement layer 7 can exert a stronger binding effect between the inner belt ply 8A and the outer belt ply 8B, thereby further improving the turning performance of the tire 1.

[0029] The inner belt cord 8a in this embodiment is an organic fiber cord. Examples of materials for the inner belt cord 8a include aramid, cellulose fiber, polyester, and nylon. Such an inner belt ply 8A is easy to bend, which promotes the deformation of the tread surface 2s during sharp turns and helps improve the turning performance of the tire 1 during sharp turns.

[0030] The outer belt cord 8b is preferably an organic fiber cord, similar to the inner belt cord 8a. Examples of materials for the outer belt cord 8b include aramid, cellulose fiber, polyester, and nylon. Such an outer belt ply 8B can work in cooperation with the inner belt ply 8A to promote deformation of the tread surface 2s during sharp turns, thereby improving the turning performance of the tire 1 during sharp turns.

[0031] The unfolded width W1 of the outer belt ply 8B should preferably be less than or equal to the tread unfolded width TWe. This prevents the outer belt ply 8B from becoming excessively large and helps to reduce the weight of the tire 1.

[0032] In this embodiment, the deployed width W1 of the outer belt ply 8B is greater than the deployed distance L1 between the outer edges of the pair of inner belt plies 8A in the tire axial direction. Such an outer belt ply 8B can suppress changes in stiffness at the outer edges of the inner belt plies 8A in the tire axial direction, thereby improving the turning performance of the tire 1 during sharp turns.

[0033] The deployed width W2 of the inner belt ply 8A is preferably 10% to 25% of the tread deployed width TWe. Such an inner belt ply 8A helps to increase the cornering force during sharp turns.

[0034] In this embodiment, the deployed width W3 of the band ply 9A is smaller than the deployed width W1 of the outer belt ply 8B. Such a band ply 9A can suppress outer diameter growth during high-speed driving and improve the straight-line stability of the tire 1 during high-speed driving. In addition, this tread reinforcement layer 7 suppresses changes in rigidity at the ends of the band ply 9A and can improve the cornering performance of the tire 1.

[0035] The deployed width W3 of the band ply 9A is preferably 40% to 65% of the tread deployed width TWe. By having a deployed width W3 of the band ply 9A of 40% or more of the tread deployed width TWe, the band ply 9A can be reliably present in the area that makes contact with the ground during straight-line driving, thereby improving the straight-line stability of the tire 1 during high-speed driving.

[0036] By ensuring that the band ply 9A's deployed width W3 is 65% or less of the tread deployed width TWe, deformation of the tread surface 2s is promoted during cornering, generating a force due to the difference in outer diameter between the inner and outer sides of the contact patch, thereby improving the cornering performance of the tire 1. Such a band ply 9A increases the camber thrust due to the deformation of the tread surface 2s, which helps improve the cornering performance of the tire 1 during sharp turns.

[0037] The distance L2 between the inner belt ply 8A and the band ply 9A is preferably 0 to 5 mm. Such a tread reinforcement layer 7 helps to reduce the change in stiffness between the inner belt ply 8A and the band ply 9A, thereby improving the turning performance of the tire 1.

[0038] While particularly preferred embodiments of this disclosure have been described in detail above, this disclosure can be implemented in various forms without being limited to the embodiments described above. [Examples]

[0039] A motorcycle tire with the basic structure shown in Figure 1 was prototyped based on the specifications in Table 1. The prototype tire was mounted on the front and rear wheels of a test motorcycle, and its straight-line stability at high speeds and its cornering performance during sharp turns were evaluated subjectively by a test driver. The results are expressed as an index with Comparative Example 1 set to 100, where a higher value indicates superior straight-line stability and cornering performance. The main common features are as follows:

[0040] <Common matters> Front tire size: 120 / 70R17 Front tire pressure: 250kPa Front wheel rim size: 17×3.50MT Rear tire size: 200 / 60R17 Rear tire pressure: 290kPa Rear wheel rim size: 17×6.00MT Test motorcycle: Large motorcycle

[0041] The test results are shown in Table 1. [Table 1]

[0042] The test results showed that the tire in the example improved cornering performance while maintaining straight-line stability at high speeds at a level equal to or better than the comparative example, confirming that it is possible to achieve both straight-line stability and cornering performance at high speeds.

[0043] [Note] This disclosure is as follows:

[0044] [Disclosure 1] A motorcycle tire comprising a carcass extending from a tread portion through a pair of sidewall portions to a pair of bead portions, and a tread reinforcing layer disposed on the radially outside of the carcass in the tread portion, wherein the tread reinforcing layer comprises a belt layer and a band layer, the band layer comprises at least one band ply with band cords arranged at an angle of 5° or less with respect to the circumferential direction of the tire, the belt layer comprises a pair of inner belt plies disposed on both sides of the band ply in the axial direction of the tire without overlapping the band ply, and at least one outer belt ply disposed on the radially outside of the band ply so as to overlap the band ply, the inner belt ply having inner belt cords arranged at an angle different from the angle of the band cords with respect to the circumferential direction of the tire, and the outer belt ply having outer belt cords arranged at an angle different from the angle of the band cords and the angle of the inner belt cords with respect to the circumferential direction of the tire.

[0045] [Disclosure 2] The motorcycle tire according to Disclosure 1, wherein the angle of the outer belt cord with respect to the tire circumferential direction is 70 to 90°.

[0046] [Disclosure 3] A motorcycle tire according to disclosure 1 or 2, wherein the angle of the inner belt cord with respect to the tire circumferential direction is 20 to 50°.

[0047] [Disclosure 4] The motorcycle tire according to any one of disclosures 1 to 3, wherein the outer belt cord and the inner belt cord are inclined in opposite directions with respect to the circumferential direction of the tire.

[0048] [Disclosure 5] The motorcycle tire according to any one of disclosures 1 to 3, wherein the outer belt cords are arranged symmetrically with respect to the tire equator.

[0049] [Disclosure 6] A motorcycle tire according to any one of disclosures 1 to 5, wherein the deployed width of the band ply is smaller than the deployed width of the outer belt ply.

[0050] [Disclosure 7] The motorcycle tire according to any one of disclosures 1 to 6, wherein the band ply's deployed width is 40% to 65% of the tread's deployed width.

[0051] [Disclosure 8] The motorcycle tire according to any one of disclosures 1 to 7, wherein the unfolded width of the outer belt ply is less than or equal to the unfolded width of the tread.

[0052] [Disclosure 9] A motorcycle tire according to any one of disclosures 1 to 8, wherein the unfolded width of the outer belt ply is greater than the unfolded distance between the outer edges of the pair of inner belt plies in the tire axial direction.

[0053] [Disclosure 10] A motorcycle tire according to any one of disclosures 1 to 9, wherein the distance between the inner belt ply and the band ply is 0 to 5 mm.

[0054] [Disclosure 11] The motorcycle tire according to any one of disclosures 1 to 10, wherein the inner belt cord is an organic fiber cord. [Explanation of symbols]

[0055] 1. Motorcycle tires 7. Tread reinforcement layer 8 Belt Layer 8A Inner Belt Ply 8B Outer Belt Ply 8a Inner belt cord 8b Outer belt cord 9-band layer 9A Bandply 9a Bandcode

Claims

1. Motorcycle tires, The carcass includes a tread portion, a pair of sidewall portions, and a pair of bead portions, and a tread reinforcing layer disposed on the radially outer side of the carcass in the tread portion. The tread reinforcement layer includes a belt layer and a band layer, The band layer includes at least one band ply in which band cords are arranged at an angle of 5° or less with respect to the circumferential direction of the tire. The belt layer includes a pair of inner belt plies arranged on both sides of the band ply in the tire axial direction so as not to overlap the band ply, and at least one outer belt ply arranged on the outside of the band ply in the tire radial direction so as to overlap the band ply. Each of the pair of inner belt plies has an inner belt cord arranged at an angle different from the angle of the band cord with respect to the circumferential direction of the tire. The outer belt ply has outer belt cords arranged at an angle different from the angle of the band cord and the angle of the inner belt cord with respect to the circumferential direction of the tire, The outer belt cord and the inner belt cords of the pair of inner belt plies are inclined in opposite directions with respect to the circumferential direction of the tire. Motorcycle tires.

2. The motorcycle tire according to claim 1, wherein the angle of the outer belt cord with respect to the tire circumferential direction is 70° or more.

3. The motorcycle tire according to claim 1 or 2, wherein the angle of the inner belt cord with respect to the tire circumferential direction is 20 to 50°.

4. The motorcycle tire according to any one of claims 1 to 3, wherein the deployed width of the band ply is smaller than the deployed width of the outer belt ply.

5. The motorcycle tire according to any one of claims 1 to 4, wherein the deployed width of the band ply is 40% to 65% of the deployed width of the tread.

6. The motorcycle tire according to any one of claims 1 to 5, wherein the unfolded width of the outer belt ply is less than or equal to the unfolded width of the tread.

7. The motorcycle tire according to any one of claims 1 to 6, wherein the unfolded width of the outer belt ply is greater than the unfolded distance between the outer edges of the pair of inner belt plies in the tire axial direction.

8. A motorcycle tire according to any one of claims 1 to 7, wherein the distance between the inner belt ply and the band ply is 0 to 5 mm.

9. The motorcycle tire according to any one of claims 1 to 8, wherein the inner belt cord is an organic fiber cord.

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