Motorcycle tires

Abstract

To provide a motorcycle tire which exhibits excellent steering stability in high speed turning.SOLUTION: A motorcycle tire includes a carcass 6, a belt layer 7 and a band layer 8. The band layer 8 is a jointless band ply 8A. A belt cord 13 of the belt layer 7 crosses a carcass cord 10 at an intersection angle θc in a tread crown region Cr, and crosses the carcass cord 10 at an intersection angle θs in a tread shoulder region Ch. The intersection angle θc is larger than the intersection angle θs.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a tire for a motorcycle. [Background technology]

[0002] The following Patent Document 1 describes a motorcycle tire having a carcass layer, a belt layer, and a belt reinforcing layer in the tread portion. In the motorcycle tire, the cord angles of the cords forming the carcass layer, the cords forming the belt layer, and the organic fiber cords forming the belt reinforcing layer are specified. As a result, the motorcycle tire of Patent Document 1 is said to have excellent steering stability during cornering. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5179803 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for further improvement in steering stability during turns, particularly during high-speed turns at speeds of 70 km / h or more.

[0005] The present invention has been devised in view of the above-mentioned circumstances, and has as its main object to provide a motorcycle tire having improved steering stability during cornering, particularly during high-speed cornering. [Means for solving the problem]

[0006] The present invention is a tire for motorcycles, comprising: a tread portion, a pair of sidewall portions, a pair of bead portions, a toroidal carcass extending between the pair of bead portions, and a belt layer and a band layer disposed on the radially outer side of the carcass in the tire radial direction and inside the tread portion, the carcass including a plurality of carcass cords, the band layer being a jointless band ply including band cords spirally disposed at an angle of 5° or less with respect to the tire circumferential direction, the belt layer including a plurality of belt cords disposed in a direction intersecting with the carcass cords, the belt cords intersect with the carcass cords in a tread crown region at a crossing angle θc, and intersect with the carcass cords in a tread shoulder region at a crossing angle θs, the crossing angle θc being greater than the crossing angle θs.

[0007] In the motorcycle tire according to the present invention, it is preferable that the band layer is disposed radially inward of the belt layer.

[0008] In the motorcycle tire according to the present invention, the width of the band layer in the axial direction of the tire is preferably 0.5 to 0.9 times the width of the belt layer in the axial direction of the tire.

[0009] In the motorcycle tire according to the present invention, the crossing angles θc and θs are preferably in the range of 20 to 65 degrees.

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

[0011] In the motorcycle tire according to the present invention, it is preferable that the axially outer end of the belt layer is positioned at a distance of 70% to 100% of the tread development half width from the tire equator.

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

[0013] In the motorcycle tire according to the present invention, it is preferable that the tread shoulder region has a width of 30% or more of the tread developed half width from the tread end toward the axially inner side of the tire. Effect of the Invention

[0014] The motorcycle tire of the present invention, by adopting the above-mentioned configuration, can exhibit excellent steering stability during high-speed cornering. [Brief description of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view showing one embodiment of a motorcycle tire of the present invention. [Diagram 2] FIG. 2 is a development view of the inside of the tread portion of FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a tire meridian cross-sectional view including a tire rotation axis (not shown) of a motorcycle tire 1 (hereinafter, sometimes simply referred to as "tire") according to this embodiment in a normal state. The tire 1 according to this embodiment is suitably used for on-road driving on dry asphalt roads, for example. However, the tire 1 of the present invention is not limited to this embodiment.

[0017] The "normal state" refers to a state in which the tire 1 is mounted on a normal rim (not shown), inflated to normal internal pressure, and unloaded. Unless otherwise specified, the dimensions of each part of the tire are values ​​measured in the normal state.

[0018] A "genuine rim" is a rim that is defined for each tire by a standard system including the standard on which tire 1 is based, such as a standard rim in the case of JATMA, a "Design Rim" in the case of TRA, and a "Measuring Rim" in the case of ETRTO.

[0019] "Normal internal pressure" refers to the air pressure set for each tire by each standard in the standard system including the standard on which tire 1 is based, and is the maximum air pressure in the case of JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" in the case of TRA, and "INFLATION PRESSURE" in the case of ETRTO.

[0020] 1, a tire 1 of this embodiment includes a tread portion 2, a pair of sidewall portions 3, and a pair of bead portions 4. In the tire 1, for example, in a tire meridian cross section, an outer surface 2a of the tread portion 2 is curved in a convex arc shape radially outwardly in the tire.

[0021] In this embodiment, the tread portion 2 includes a tread crown region Cr including the tire equator C, and tread shoulder regions Sh arranged on both sides of the tread crown region Cr. The tread crown region Cr extends, for example, on both sides in the tire axial direction with the tire equator C as the center. The tread shoulder region Sh has a width Ws of 30% or more of the tread development half width Bw from the tread end Te to the inside in the tire axial direction. The width Ws of the tread shoulder region Sh is, for example, 40% or less of the tread development half width Bw from the tread end Te to the inside in the tire axial direction. The "tread development half width Bw" is 0.5 times the length in the tire axial direction between the tread ends Te, Te when the tread portion 2 is developed on a plane.

[0022] The pair of sidewall portions 3 are connected to both axial ends of the tread portion 2 and extend radially inwardly of the tire. Each of the pair of bead portions 4 is connected to, for example, each sidewall portion 3 and extends radially inwardly of the tire. A bead core 5 is embedded in each bead portion 4.

[0023] The tire 1 of this embodiment includes a toroidal carcass 6 extending between a pair of bead portions 4, and a belt layer 7 and a band layer 8 arranged radially outside the carcass 6 and inside the tread portion 2.

[0024] Fig. 2 is a development view of the inside of the tread portion 2. As shown in Fig. 2, the carcass 6 includes a plurality of carcass cords 10. The band layer 8 is a jointless band ply 8A including band cords 11 arranged in a spiral shape at an angle θa of 5° or less with respect to the tire circumferential direction. Such a band layer 8 suppresses the growth of the tire outer diameter and improves high-speed stability during straight running. The belt layer 7 includes a plurality of belt cords 13 arranged in a direction intersecting the carcass cords 10.

[0025] In addition, the belt cord 13 intersects with the carcass cord 10 at a crossing angle θc in the tread crown region Cr, and intersects with the carcass cord 10 at a crossing angle θs in the tread shoulder region Sh. The crossing angle θc is larger than the crossing angle θs. As a result, the shear rigidity is increased in the tread shoulder region Sh, and a large hoop effect is exhibited, making it possible to withstand a large centrifugal force. Therefore, the tire 1 of this embodiment exhibits excellent steering stability performance during high-speed cornering. In addition, in the tread crown region Cr, the crossing angle θc is relatively small, so that the shear rigidity does not become excessively high, and ride comfort performance and high-speed stability performance during straight driving are maintained.

[0026] The crossing angles θc and θs are preferably in the range of 20 to 65 degrees. Since the crossing angles θc and θs are 65 degrees or less, a hoop effect is obtained, and stability in straight running and cornering is ensured. If the crossing angles θc and θs are less than 20 degrees, the hoop effect is not exerted. From this viewpoint, the crossing angles θc and θs are more preferably 25 degrees or more, even more preferably 30 degrees or more, more preferably 60 degrees or less, and even more preferably 55 degrees or less.

[0027] The difference (θc-θs) between the crossing angles θc and θs is preferably 3 to 20 degrees. Since the difference (θc-θs) is 3 degrees or more, the stability performance during both 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 is reduced, and the steering operation from straight running to cornering and from cornering to straight running becomes smooth, improving the stability performance. For this reason, the difference (θc-θs) is more preferably 5 degrees or more, and more preferably 15 degrees or less.

[0028] In this embodiment, the crossing angle θc is an angle on the tire equator C. The crossing angle θs is a position P that is 30% of the tread developed half width Tw from the tread end Te to the inside in the tire axial direction. Furthermore, when the carcass 6 or the belt layer 7 is composed of a plurality of plies, the crossing angles θc and θs are determined by the cord of the ply of the carcass 6 arranged on the outermost side in the tire radial direction and the cord of the ply of the belt layer 7 arranged on the innermost side in the tire radial direction.

[0029] The carcass 6 is formed, for example, including at least one carcass ply in which the carcass cords 10 are covered with a topping rubber. In this embodiment, the carcass 6 is formed of two carcass plies 6A, 6B overlapped on the inside and outside in the tire radial direction. Each carcass ply 6A, 6B extends, for example, so as to straddle both bead cores 5, 5 (shown in FIG. 1).

[0030] In this embodiment, the inner carcass ply 6A and the outer carcass ply 6B are arranged such that the carcass cords 10 cross each other on the inside and outside in the tire radial direction. Each carcass cord 10 is made of, for example, an organic fiber cord.

[0031] The carcass cord 10 of this embodiment has an angle θ1 with respect to the tire circumferential direction that increases from the tire equator C toward both tread ends Te. Such a carcass cord 10 increases the rigidity in the tire axial direction on the tread end Te side, and increases the rigidity in the tire circumferential direction on the tire equator C side. For example, the angle θ1 of the carcass cord 10 gradually increases from the tire equator C toward both tread ends Te side.

[0032] The angle θ1a of the carcass cord 10 with respect to the tire circumferential direction is preferably, for example, 25 to 70 degrees. Since the angle θ1a is 25 degrees or more and 70 degrees or less, an effective hoop effect is exhibited in both carcass plies 6A, 6B. Therefore, the angle θ1a is more preferably 30 degrees or more and more preferably 65 degrees or less. The angle θ1a is an angle on the tread crown region Cr, more specifically, on the tire equator C.

[0033] In addition, the angle θ1b of the carcass cord 10 in the tread shoulder region Sh, more specifically, at the position P with respect to the tire circumferential direction is preferably 35 degrees or more, more preferably 40 degrees or more, and is preferably 80 degrees or less, and even more preferably 75 degrees or less. This allows the above-mentioned effects to be effectively exhibited.

[0034] As shown in FIG. 1, the axially outer end 8e of the band layer 8 is located, for example, axially inward of the axially outer end 7e of the belt layer 7. The band layer 8 of this embodiment is disposed radially inward of the belt layer 7. In other words, the band layer 8 is sandwiched between the carcass 6 and the belt layer 7 in this embodiment. This allows the belt layer 7 to absorb the impact transmitted to the vehicle handlebars when the axially outer end 8e of the band layer 8 touches the ground when the camber angle is changed. This further improves the steering stability during high-speed cornering.

[0035] The width Wb of the band layer 8 in the tire axial direction is preferably 0.5 to 0.9 times the width Wa of the belt layer 7 in the tire axial direction. Since the width Wb of the band layer 8 is 0.5 times or more the width Wa of the belt layer 7, high-speed stability during straight driving is improved. Since the width Wb of the band layer 8 is 0.9 times or less the width Wa of the belt layer 7, handling stability during high-speed cornering is improved.

[0036] In order to effectively exert the above-mentioned action, it is desirable that the axially outer end 7e of the belt layer 7 be located along the outer surface 2a of the tread portion 2 at 70% to 100% of the tread development half width Bw from the tire equator C.

[0037] As shown in Fig. 2, the belt cord 13 of the belt layer 7 extends linearly in this embodiment. For example, the angle θ2 of the belt cord 13 with respect to the tire circumferential direction may be gradually increased from the tire equator C toward the tread end Te. The angle θ2 of the belt cord 13 with respect to the tire circumferential direction is preferably 85 degrees or more. This allows the tire 1 to have high axial rigidity. The angle θ2 of the belt cord 13 is more preferably 88 degrees or more, and even more preferably 90 degrees.

[0038] Although the motorcycle tire according to one embodiment of the present invention has been described in detail above, the present invention is not limited to the above-mentioned specific embodiment and can be modified and carried out in various aspects. EXAMPLES

[0039] Motorcycle tires with the basic structure shown in Fig. 1 were prototyped. Each sample tire was then tested for steering stability during high-speed driving, steering stability during low-speed driving (less than 70 km / h), and high-speed stability during straight driving. The common specifications and test methods for each sample tire are as follows:

[0040] <Handling stability during high-speed driving, handling stability during low-speed driving, and high-speed stability during straight driving> A test rider drove a test vehicle equipped with a sample tire on a test course with a dry asphalt surface. After the drive, the test rider evaluated each test item by sensory evaluation. The evaluation was done on a 10-point scale with 10 being the maximum score. The higher the numerical value, the better the test item. Note that "position 7e" in Table 1 refers to the tread development length / half tread development width between the axial outer end of the belt layer and the tire equator. Front tire (size, rim, internal pressure): 110 / 70-13M / C, 13×3.00MT, 200kPa Rear tire (size, rim, internal pressure): 130 / 70-13M / C, 13×3.50MT, 220kPa Test vehicle: 1000cc motorcycle The test results are shown in Table 1.

[0041] [Table 1]

[0042] As a result of the test, it was confirmed that the tire of the embodiment exhibited excellent steering stability performance during high-speed driving. In addition, it was confirmed that the tire of the embodiment also had improved steering stability performance during low-speed driving and high-speed stability performance during straight driving. [Explanation of symbols]

[0043] 1. Motorcycle tires 6. Carcass 7 Belt layer 8 Band Layer 8A Jointless Band Ply 10 Carcass Cord 13 Belt cord Cr Tread crown area Sh Tread shoulder area

Claims

1. A tire for a motorcycle, A tread portion; A pair of sidewall portions; A pair of bead portions; a toroidal carcass extending between the pair of bead portions; A belt layer and a band layer are disposed on the outer side of the carcass in the tire radial direction and inside the tread portion, The carcass includes a plurality of carcass cords, the band layer is a jointless band ply including a band cord arranged in a spiral shape 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 cord intersects with the carcass cord at a crossing angle θc in a tread crown region, and intersects with the carcass cord at a crossing angle θs in a tread shoulder region, The crossing angle θc is larger than the crossing angle θs, The carcass cord has an angle θ1 with respect to the tire circumferential direction increasing from the tire equator toward both tread ends. Tires for motorcycles.

2. The motorcycle tire according to claim 1 , wherein the band layer is disposed radially inward of the belt layer.

3. 3. The motorcycle tire according to claim 1, wherein the width of the band layer in the tire axial direction is 0.5 to 0.9 times the width of the belt layer in the tire axial direction.

4. The motorcycle tire according to any one of claims 1 to 3, wherein the crossing angles θc and θs are in a range of 20 to 65 degrees.

5. The motorcycle tire according to claim 1 , wherein an angle of the belt cord with respect to a circumferential direction of the tire is equal to or greater than 85 degrees.

6. The motorcycle tire according to any one of claims 1 to 5, wherein an axially outer end of the belt layer is located at a distance from the tire equator that is 70% to 100% of a half-width of a developed tread.

7. The motorcycle tire according to any one of claims 1 to 6, wherein an angle of the carcass cord with respect to the tire circumferential direction is 25 to 70 degrees.

8. 8. The motorcycle tire according to claim 1, wherein the tread shoulder region has a width that is 30% or more of a half-developed tread width from a tread end to an axially inner side of the tire.

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