Tire sets and tricycles

Abstract

To provide a tire set that is able to efficiently improve the turning performance of a tricycle, and to provide a tricycle equipped with the tire set.SOLUTION: A tire set for a tricycle has one wheel at one of the front and the rear and two wheels at the other. The tire set includes a first tire mounted on the one-wheel side and two second tires mounted on the two-wheel side. The cornering power Cp2 of each of the second tires is 50% or more and less than 100% of the cornering power Cp1 of the first tire.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a set of tires for a tricycle. [Background technology]

[0002] Various tires have been proposed for tricycles, whose front and rear wheels tilt relative to the road surface as the vehicle leans during cornering. For example, Patent Document 1 below proposes a tire that stabilizes the behavior of a motor tricycle by mounting a tire with a specific land ratio to the unicycle side, thereby improving the rigidity of the tread portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-070109 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the tire in Patent Document 1 only specifies the tire for one wheel and does not compare it with the tire for two wheels, so it may not be possible to propose an optimal tire that is well-balanced overall.

[0005] The present invention was devised in light of the above-described circumstances, and its main object is to provide a tire set that can efficiently improve the turning performance of a tricycle, and a tricycle equipped with such a tire set. [Means for solving the problem]

[0006] The present invention is a tire set for a tricycle having one front wheel and one rear wheel and two rear wheels, the tire set including one first tire mounted on the one-wheel side and two second tires mounted on the two-wheel side, characterized in that the cornering power of each of the second tires is 50% or more and less than 100% of the cornering power of the first tire.

[0007] In the tire set of the present invention, it is desirable that the cornering power of each of the second tires is 60% or more and 90% or less of the cornering power of the first tire.

[0008] In the tire set of the present invention, it is desirable that the land ratio of the second tire is smaller than the land ratio of the first tire.

[0009] In the tire set of the present invention, it is desirable that the land ratio of the second tire is 80% or more and 95% or less of the land ratio of the first tire.

[0010] In the tire set of the present invention, it is desirable that the first tire and the second tire each have a tread reinforcing layer in which a plurality of reinforcing cords are arranged inside a tread portion, and that a second strength expressed as the product of the number of the reinforcing cords per 5 cm of ply width of the tread reinforcing layer of the second tire and the breaking strength of the reinforcing cords is smaller than a first strength expressed as the product of the number of the reinforcing cords per 5 cm of ply width of the tread reinforcing layer of the first tire and the breaking strength of the reinforcing cords.

[0011] In the tire set of the present invention, the second strength is preferably 70% or more and 90% or less of the first strength.

[0012] In the tire set of the present invention, it is preferable that the second tire includes a carcass disposed across a pair of bead portions, and the carcass is configured by two or less carcass plies.

[0013] In the tire set of the present invention, the carcass is preferably formed of one carcass ply.

[0014] In the tire set of the present invention, the carcass ply preferably has carcass cords arranged at an angle of 70° or more with respect to the tire equator.

[0015] In the tire set of the present invention, the second tire is preferably a radial tire.

[0016] The present invention is a tricycle having two front wheels and one rear wheel, and having a mechanism that causes the front and rear wheels to tilt relative to the road surface as the vehicle body banks during cornering, and is characterized by being equipped with the tire set described above. [Effects of the Invention]

[0017] The tire set of the present invention includes one first tire mounted on one wheel side and two second tires mounted on two wheel sides, and the cornering power of each of the second tires is 50% or more and less than 100% of the cornering power of the first tire. This tire set allows for a good balance between the cornering power of the one wheel side and the cornering power of the two wheel side, thereby efficiently improving the turning performance of the tricycle. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a cross-sectional view showing one embodiment of a tire of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The tire set of this embodiment is suitable for mounting on a tricycle with one front wheel or one rear wheel and two wheels. The tricycle of this embodiment has a mechanism that allows the front and rear wheels to tilt relative to the road surface as the vehicle body bank during cornering. For example, the tricycle may have two front wheels and one rear wheel. This type of tricycle has a good balance of cornering ability and maneuverability.

[0020] The tire set for a tricycle of this embodiment includes one first tire mounted on one wheel and two second tires mounted on the other wheel. The cornering power Cp2 of each of the second tires is preferably 50% or more and less than 100% of the cornering power Cp1 of the first tire. This tire set allows for a good balance between the cornering power Cp1 of the one wheel and the cornering power Cp2 of the two wheels, thereby efficiently improving the turning performance of the tricycle.

[0021] By making the cornering power Cp2 of the second tire 50% or more of the cornering power Cp1 of the first tire, it is possible to prevent the cornering power Cp2 of the two wheels from being excessively insufficient. From this perspective, the cornering power Cp2 of each of the second tires is more preferably 60% or more, and even more preferably 70% or more of the cornering power Cp1 of the first tire.

[0022] By making the cornering power Cp2 of the second tires less than 100% of the cornering power Cp1 of the first tires, it is possible to prevent the cornering power Cp2 of the two wheels from becoming excessive. From this perspective, the cornering power Cp2 of each of the second tires is more preferably 90% or less, and even more preferably 80% or less, of the cornering power Cp1 of the first tires.

[0023] In a more preferred embodiment, the first tire and the second tire may have the same structure or may have different structures. The first tire and the second tire (hereinafter collectively referred to as "tire 1") may have, for example, a well-known structure as appropriate. One embodiment of tire 1 will be described below.

[0024] 1 is a tire meridian cross-sectional view showing a tire 1 of this embodiment in a normal state. Here, the "normal state" refers to a state in which the tire 1 is mounted on a normal rim, adjusted to a normal internal pressure, and no load is applied. In this specification, unless otherwise specified, the dimensions of each part of the tire 1 are values ​​measured in the normal state.

[0025] A "genuine rim" is a rim that is specified for each tire in a standard system that includes the standard on which tire 1 is based, such as a "standard rim" for JATMA, a "design rim" for TRA, or a "measuring rim" for ETRTO. If there is no standard system that includes the standard on which tire 1 is based, a "genuine rim" is a rim that is specified for each tire by the manufacturer, etc.

[0026] "Normal internal pressure" is the air pressure specified for each tire by the standard system, including the standard on which tire 1 is based. For JATMA, it 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." If there is no standard system including the standard on which tire 1 is based, "normal internal pressure" is the air pressure specified for each tire by the manufacturer, etc.

[0027] As shown in Fig. 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. The tread portion 2 is, for example, a portion that comes into contact with the ground by rotating. Both ends of the tread portion 2 in the tire axial direction are tread ends Te. The center position in the tire axial direction between both tread ends Te is the tire equator C.

[0028] In the tire meridian cross section, the tread portion 2 preferably has an arc-shaped profile that is convex radially outward in the tire direction so that a sufficient contact area can be obtained even when cornering with a large camber angle. Such a tread portion 2 is suitable for generating the camber thrust required when cornering.

[0029] The tread portion 2 includes, for example, land portions for contacting the road surface and groove portions for draining water. The tread portion 2 has a land ratio Ld for each tire 1, which is the area of ​​only the land portions of the tread portion 2 divided by the total area including the land portions and groove portions.

[0030] In this embodiment, the land ratio Ld2 of the second tires is smaller than the land ratio Ld1 of the first tires. Such second tires can have lower rigidity than the first tires, which helps to make the cornering power Cp2 of each second tire smaller than the cornering power Cp1 of the first tires.

[0031] The land ratio Ld2 of the second tire is preferably 80% or more of the land ratio Ld1 of the first tire. By making the land ratio Ld2 of the second tire 80% or more of the land ratio Ld1 of the first tire, it is possible to prevent the rigidity of the second tire from becoming excessively insufficient. From this perspective, the land ratio Ld2 of the second tire is more preferably 83% or more of the land ratio Ld1 of the first tire, and even more preferably 85% or more.

[0032] The land ratio Ld2 of the second tire is preferably 95% or less of the land ratio Ld1 of the first tire. By making the land ratio Ld2 of the second tire 95% or less of the land ratio Ld1 of the first tire, the rigidity of the second tire can be reduced, and the cornering power Cp2 of each of the second tires can be made smaller than the cornering power Cp1 of the first tire. From this perspective, the land ratio Ld2 of the second tire is more preferably 92% or less of the land ratio Ld1 of the first tire, and even more preferably 90% or less.

[0033] The sidewall portions 3 are, for example, portions located on both sides of the tread portion 2 in the tire axial direction and radially inward of the tread portion 2. The bead portions 4 are, for example, portions located radially inward of the sidewall portions 3. It is desirable that a bead core 5 is embedded in each of the bead portions 4.

[0034] The tire 1 of this embodiment includes a carcass 6 disposed across a pair of bead portions 4, and a tread reinforcing layer 7 disposed outside the carcass 6 in the tire radial direction and inside the tread portion 2.

[0035] The carcass 6 is composed of at least one carcass ply 6A, one carcass ply in this embodiment. The carcass ply 6A includes a main body portion 6a that extends from the tread portion 2 through the sidewall portion 3 to the bead cores 5 of the bead portions 4, and a turned-up portion 6b that is continuous with the main body portion 6a and turned up around the bead cores 5.

[0036] It is desirable to provide a bead apex rubber 8 between the main body portion 6a and the folded-back portion 6b. The bead apex rubber 8 is made of, for example, hard rubber. This effectively reinforces the bead portion 4.

[0037] The carcass 6 of the first tire is made up of, for example, one to three carcass plies 6A. Such a first tire can improve the cornering power Cp1 of the single wheel side by improving the rigidity of the single wheel side, which helps to improve the turning performance of the tricycle.

[0038] The carcass 6 of the second tire is preferably composed of two or less carcass plies 6A. In this embodiment, the carcass 6 of the second tire is composed of one carcass ply 6A. Such a second tire can have lower rigidity than the first tire, which helps to make the cornering power Cp2 of each second tire smaller than the cornering power Cp1 of the first tire. Furthermore, such a second tire can reduce the weight of the two wheels, which helps to improve the turning performance of the tricycle.

[0039] The carcass ply 6A preferably has carcass cords arranged at an angle with respect to the tire equator C. For the carcass cords, organic fiber cords such as nylon, polyester, or rayon are preferably used.

[0040] The carcass ply 6A of the second tire has carcass cords arranged at an angle of preferably 70° or more with respect to the tire equator C. By setting the carcass cord angle to 70° or more, the cornering power Cp2 of each of the second tire can be reduced, thereby improving the turning performance and high-speed stability of the tricycle. From this perspective, the angle of the carcass cords of the second tire is more preferably 80° or more, and even more preferably 90°.

[0041] The tread reinforcing layer 7 is made up of at least one reinforcing ply 7A, 7B, two in this embodiment. Each of the reinforcing plies 7A, 7B has a plurality of reinforcing cords arranged inclined at an angle of 5 to 40 degrees with respect to the tire equator C, for example. The tread reinforcing layer 7 is preferably constructed by overlapping the reinforcing cords of the two reinforcing plies 7A, 7B in directions that cross each other. Suitable reinforcing cords are, for example, steel cords, aramid cords, rayon cords, or the like.

[0042] The second strength St2 of the tread reinforcing layer 7 of the second tire is desirably smaller than the first strength St1 of the tread reinforcing layer 7 of the first tire. Such a tread reinforcing layer 7 helps to make the cornering power Cp2 of each of the second tires smaller than the cornering power Cp1 of the first tire.

[0043] Here, the first strength St1 is expressed as the product of the number of reinforcing cords per 5 cm of ply width in the tread reinforcing layer 7 of the first tire and the breaking strength of the reinforcing cords. When the first tire is made up of two reinforcing plies 7A, 7B, the number of reinforcing cords per 5 cm of ply width in the tread reinforcing layer 7 of the first tire is the average number of reinforcing cords per 5 cm of ply width in each of the reinforcing plies 7A, 7B. Note that in this specification, the number of reinforcing cords per 5 cm of ply width in each of the reinforcing plies 7A, 7B refers to the number of reinforcing cords per 5 cm of ply width in the direction perpendicular to the longitudinal direction of the reinforcing cords in each of the reinforcing plies 7A, 7B.

[0044] Furthermore, the second strength St2 is expressed as the product of the number of reinforcing cords per 5 cm of ply width in the tread reinforcing layer 7 of the second tire and the breaking strength of the reinforcing cords. When the second tire is made up of two reinforcing plies 7A and 7B, the number of reinforcing cords per 5 cm of ply width in the tread reinforcing layer 7 of the second tire is the average number of reinforcing cords per 5 cm of ply width in each of the reinforcing plies 7A and 7B.

[0045] The second strength St2 is preferably 70% or more of the first strength St1. By making the second strength St2 70% or more of the first strength St1, an excessive decrease in the cornering power Cp2 on the two-wheel side can be suppressed, and the turning performance of the tricycle can be improved. From this perspective, the second strength St2 is more preferably 72% or more of the first strength St1, and even more preferably 75% or more.

[0046] The second strength St2 is preferably 90% or less of the first strength St1. By making the second strength St2 90% or less of the first strength St1, the cornering power Cp2 on the two-wheel side is prevented from becoming excessive, and the turning performance of the tricycle can be improved. From this perspective, the second strength St2 is more preferably 88% or less of the first strength St1, and even more preferably 85% or less.

[0047] The tire 1 of this embodiment may be either a radial tire or a bias tire. The second tire is preferably a radial tire. The first tire is more preferably a radial tire. Such a tire 1 has excellent high-speed stability.

[0048] Although a particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment and can be modified and practiced in various ways. [Example]

[0049] A set of first and second tires with the basic structure shown in Figure 1 was prototyped based on the specifications in Table 1. These prototype tires were mounted on all wheels of a test vehicle, and cornering performance and high-speed stability were tested. The common specifications and test methods for each test tire are as follows:

[0050] <Common specifications> Test vehicle: Three-wheeled vehicle with two front wheels and one rear wheel Front tire size: 120 / 70ZR15 Rear tire size: 190 / 55ZR17

[0051] <Turnability> A test rider drove a test vehicle fitted with the prototype tires and evaluated the stability during cornering based on his or her senses. The results were displayed on a 5-point scale, with a higher score indicating better cornering.

[0052] <High-speed stability> Test riders rode test vehicles fitted with prototype tires and evaluated the stability at high speeds based on their senses. The results were displayed on a 5-point scale, with higher scores indicating better high-speed stability.

[0053] The test results are shown in Table 1. [Table 1]

[0054] As a result of the test, it was confirmed that the tire set of the example had superior cornering characteristics and equal or better high-speed stability than the comparative example. [Explanation of symbols]

[0055] Cp1 Cornering Power Cp2 Cornering Power

Claims

1. A tire set for a tricycle having one front wheel and one rear wheel and two wheels, a first tire mounted on the first wheel side and two second tires mounted on the second wheel side, the cornering power of each of the second tires is equal to or greater than 50% and less than 100% of the cornering power of the first tires; The first tire and the second tire each include a tread reinforcing layer in a tread portion, the tread reinforcing layer including a plurality of reinforcing cords arranged therein, a second strength expressed by the product of the number of the reinforcement cords per 5 cm of a ply width of the tread reinforcing layer of the second tire and the breaking strength of the reinforcement cords is smaller than a first strength expressed by the product of the number of the reinforcement cords per 5 cm of a ply width of the tread reinforcing layer of the first tire and the breaking strength of the reinforcement cords; Tire set.

2. The set of tires of claim 1 , wherein the second tire has a land ratio that is less than the land ratio of the first tire.

3. The tire set according to claim 2 , wherein a land ratio of the second tire is equal to or greater than 80% and equal to or less than 95% of a land ratio of the first tire.

4. The tire set according to claim 1 , wherein the second strength is equal to or greater than 70% and equal to or less than 90% of the first strength.

5. the second tire includes a carcass disposed across a pair of bead portions, The tire set according to claim 1 , wherein the carcass is composed of two or less carcass plies.

6. The tire set according to claim 5 , wherein the carcass is constituted by one carcass ply.

7. The tire set according to claim 5 or 6, wherein the carcass ply has carcass cords arranged at an angle of 70° or more with respect to the tire equator.

8. The tire set according to claim 1 , wherein the second tire is a radial tire.

9. a tricycle having two front wheels and one rear wheel, the tricycle having a mechanism that allows the front wheels and the rear wheels to tilt with respect to a road surface as the vehicle body bank during cornering, A tricycle equipped with the tire set according to any one of claims 1 to 8.

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