Airless tire

Abstract

To provide an airless tire capable of suppressing a change in a performance of a tire along with rotation.SOLUTION: An outer peripheral ring 12 includes a first reinforcing layer 21 extending in a width direction of the outer peripheral ring 12, and having a product of a shearing elastic coefficient and a thickness that varies depending on a position in the width direction of the outer peripheral ring 12 in a cross section perpendicular to a circumferential direction of a wheel 11.SELECTED DRAWING: Figure 4A

Description

[Technical field]

[0001] The present invention relates to an airless tire (also called a non-pneumatic tire or a non-pneumatic tire). [Background technology]

[0002] An airless tire is known that includes fins that radially connect annular outer peripheral member and inner peripheral member, and a spoke structure in which the fins are arranged intermittently in the circumferential direction and are joined to the inner peripheral side of a tread ring, with multiple spoke structures arranged in the tire width direction so that the positions of the fins on adjacent spoke structures are staggered in the circumferential direction (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-055928 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned conventional technology, the fins are arranged intermittently in the circumferential direction, which causes a problem in that the contact pressure of the tire changes with rotation, affecting tire performance such as tread wear.

[0005] The problem to be solved by the present invention is to provide an airless tire that can suppress changes in tire performance that occur during rotation. [Means for solving the problem]

[0006] The present invention solves the above problem by providing an outer ring having a first reinforcing layer extending in the width direction of the outer ring and in a cross section perpendicular to the circumferential direction of the wheel, the product of the shear modulus and the thickness of which varies depending on the position in the width direction of the outer ring. Effect of the Invention

[0007] According to the present invention, changes in tire performance caused by rotation can be suppressed. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a front view illustrating an example of an airless tire according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a front view illustrating another example of an airless tire according to an embodiment of the present invention. [Diagram 3] FIG. 3 is a perspective view of a main part showing the cross section AA of FIG. 2. [Figure 4A] 3 is a cross-sectional view of a main part of the airless tire of FIG. 2 taken along a plane perpendicular to the circumferential direction. [Figure 4B] 3 is a cross-sectional view showing a main part of another example of the outer circumferential ring of FIG. 2. [Diagram 5] 1 is a cross-sectional view showing a main portion of an example of an outer circumferential ring according to an embodiment of the present invention. [Figure 6] 13 is a cross-sectional view showing a main portion of another example of an outer circumferential ring according to an embodiment of the present invention. FIG. [Figure 7] 13 is a cross-sectional view showing a main portion of yet another example of an outer circumferential ring according to an embodiment of the present invention. FIG. [Figure 8] 13 is a cross-sectional view showing a main portion of yet another example of an outer circumferential ring according to an embodiment of the present invention. FIG. [Figure 9] 1 is a cross-sectional view showing a main part of an example of an outer circumferential ring according to a comparative example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. For ease of explanation, the side (or outer side) of a vehicle on which an airless tire is mounted is defined as the front side. In addition, in the drawings, "front" indicates the front of the vehicle, "rear" indicates the rear of the vehicle, "right" indicates the right side of the vehicle, "left" indicates the left side of the vehicle, "up" indicates the top of the vehicle, and "down" indicates the bottom of the vehicle. Furthermore, in the following explanation, the radial direction of the airless tire will be simply referred to as the radial direction, and the circumferential direction of the airless tire will be simply referred to as the circumferential direction. It is assumed that the radial direction of the airless tire is the same direction as the radial direction of the wheel, and the circumferential direction of the airless tire is the same direction as the circumferential direction of the wheel.

[0010] [Airless tire configuration] Fig. 1 is a front view showing an example of an airless tire according to an embodiment of the present invention. An airless tire is a tire that supports a vehicle body not by air pressure but by the reaction force of spokes made of an elastic material (hereinafter also referred to as an elastic material). The airless tire of this embodiment can be applied to wheels of four-wheeled automobiles, two-wheeled automobiles, industrial vehicles, bicycles, and other vehicles, as well as carts and the like. As shown in Fig. 1, the airless tire 1 of this embodiment includes a wheel 11, an outer peripheral ring 12, spokes 13, and a tread 14.

[0011] The wheel 11 is a member that is fixed to a hub (not shown) of the vehicle to connect with the vehicle, and is made of metal or other highly rigid material. The wheel 11 is made up of, for example, a disk-shaped disc and a cylindrical rim. The disc is shown in FIG. 1 as a circular member in the center of the airless tire 1, and the airless tire 1 is supported on the axle by fixing the disc to the hub of the vehicle. The shape of the wheel 11 can be set appropriately according to the required specifications of the airless tire 1. The disc and rim may be molded as a single unit, or may be combined after being molded separately.

[0012] The outer circumferential ring 12 is a cylindrical member having the tire width, and is a member for reinforcing the tread 14 made of an elastic material. The outer circumferential ring 12 is made of a composite material made of an elastic material such as natural rubber or synthetic rubber, and a reinforcing material such as a tire cord made of metal or resin. The outer circumferential side of the outer circumferential ring 12 is joined to the tread 14 on the inner circumferential side of the tread 14. Specifically, the outer circumferential surface of the outer circumferential ring 12 and the inner circumferential surface of the tread 14 are bonded to each other by an adhesive. The outer circumferential ring 12 may be integrally molded with the tread 14. The shape (thickness) and strength of the outer circumferential ring 12 can be appropriately set according to the required specifications of the airless tire 1.

[0013] The spokes 13 are members that support a load (e.g., the vehicle weight) applied to the airless tire 1, and are plate-like members made of an elastic material such as an elastic thermoplastic resin or an elastic thermosetting resin, and have a width corresponding to the tire width. The spokes 13 extend radially from the outer periphery side of the wheel 11 (specifically, the outer periphery side of the rim) toward the inner periphery side of the outer periphery ring 12, and are provided in plurality at equal intervals and spaced apart from each other along the circumferential direction of the airless tire 1. The plurality of spokes 13 are provided axially symmetrically with respect to the central axis of the airless tire 1. The number of spokes 13 provided on one airless tire 1 is not particularly limited, and can be set appropriately depending on the ground contact length of the airless tire 1, the load bearing capacity of the spokes 13, vibration resistance, and other required specifications of the airless tire 1.

[0014] The means for attaching the spokes 13 to the wheel 11 is not particularly limited as long as robustness can be ensured. For example, grooves may be formed in the outer peripheral surface of the rim of the wheel 11, and the inner peripheral ends of the spokes 13 may be fitted into the grooves. The outer peripheral surface of the rim of the wheel 11 and the inner peripheral ends of the spokes 13 may be bonded with an adhesive, or the outer peripheral surface of the rim and the inner peripheral ends of the spokes 13 may be directly connected with bolts. Similarly, the means for attaching the spokes 13 to the outer peripheral ring 12 is not particularly limited as long as robustness can be ensured. For example, the inner peripheral surface of the outer peripheral ring 12 and the outer peripheral ends of the spokes 13 may be bonded with an adhesive.

[0015] The tread 14 is a cylindrical member having a tire width, and is disposed on the outermost periphery of the airless tire 1 to come into contact with the road surface. The tread 14 is made of an elastic material such as natural rubber or synthetic rubber, and may include a reinforcing material such as a metal or resin tire cord. A tread pattern is formed on the outer periphery of the tread 14 in the same manner as in conventional pneumatic tires, and serves as the contact surface with the road surface. The thickness of the tread 14 and the shape of the tread pattern can be appropriately set according to the required specifications of the airless tire 1.

[0016] Fig. 2 is a front view showing another example of an airless tire according to an embodiment of the present invention, and Fig. 3 is a perspective view of a main part showing a cross section taken along line AA of the airless tire shown in Fig. 2. The airless tire 1a shown in Figs. 2 and 3 includes a wheel 11, an outer peripheral ring 12, spokes 13, and a tread 14, as well as a first spoke ring 15 and a second spoke ring 16. Note that the first spoke ring 15 and the second spoke ring 16 are not essential components of the present invention, and may be omitted as necessary, as in the airless tire 1 shown in Fig. 1.

[0017] The first spoke ring 15 is an annular member that connects the inner circumferential ends of the multiple spokes 13, and is made of, for example, the same material as the spokes 13. The inner circumferential side of the first spoke ring 15 is joined to the wheel 11 on the outer circumferential side of the wheel 11. Specifically, the first spoke ring 15 may be joined by providing protrusions on its inner circumferential surface and fitting the protrusions of the first spoke ring 15 into grooves formed in the rim of the wheel 11, or the inner circumferential surface of the first spoke ring 15 and the outer circumferential surface of the rim may be bonded with an adhesive. The inner circumferential ends of the spokes 13 are joined to the first spoke ring 15, for example, with an adhesive. The spokes 13 and the first spoke ring 15 may also be molded as a single unit.

[0018] The second spoke ring 16 is an annular member that connects the outer peripheral ends of the multiple spokes 13, and is made of, for example, the same material as the spokes 13. The outer peripheral side of the second spoke ring 16 is joined to the outer peripheral ring 12 on the inner peripheral side of the outer peripheral ring 12. Specifically, the outer peripheral surface of the second spoke ring 16 is bonded to the inner peripheral surface of the outer peripheral ring 12 by an adhesive. The outer peripheral ends of the spokes 13 are joined to the second spoke ring 16 by, for example, an adhesive. Furthermore, the spokes 13 and the second spoke ring 16 may be integrally molded, or the spokes 13, the first spoke ring 15, and the second spoke ring 16 may be integrally molded.

[0019] By providing the first spoke ring 15, the bonding area with the rim of the wheel 11 is increased compared to when the spokes 13 are directly bonded to the wheel 11, improving the load-bearing capacity of the airless tire 1a. Similarly, by providing the second spoke ring 16, the bonding area with the outer peripheral ring 12 is increased compared to when the spokes 13 are directly bonded to the outer peripheral ring 12, improving the load-bearing capacity of the airless tire 1a. The first spoke ring 15 and the second spoke ring 16 have a width equivalent to the tire width (for example, a width within a range of the tire width ±10%) and an appropriate thickness according to the required specifications of the airless tire 1a.

[0020] When the airless tire includes a first spoke ring 15, the spokes 13 extend radially from the outer circumferential side of the first spoke ring 15 toward the inner circumferential side of the outer circumferential ring 12, connecting the first spoke ring 15 and the outer circumferential ring 12. When the airless tire includes a second spoke ring 16, the spokes 13 extend radially from the outer circumferential side of the rim of the wheel 11 toward the inner circumferential side of the second spoke ring 16, connecting the wheel 11 and the second spoke ring 16. When the airless tire includes a first spoke ring 15 and a second spoke ring 16 like the airless tire 1a shown in Figures 2 and 3, the spokes 13 extend radially from the outer circumferential side of the first spoke ring 15 toward the inner circumferential side of the second spoke ring 16, connecting the first spoke ring 15 and the second spoke ring 16.

[0021] [Outer ring configuration] Fig. 4A is a cross-sectional view of a main part showing a cross section perpendicular to the circumferential direction of the airless tire 1a in Fig. 2, and Fig. 4A shows the tread 14 in contact with the road surface, the outer peripheral ring 12, and the second spoke ring 16. As shown in Fig. 4A, the outer peripheral ring 12 of this embodiment has a first reinforcing layer 21 extending in the width direction of the outer peripheral ring 12 (the left-right direction in Fig. 4A). The first reinforcing layer 21 is a reinforcing layer provided in the outer peripheral ring 12 and made of a material having a higher elastic modulus than the elastic material constituting the outer peripheral ring 12, and is made of, for example, hard rubber having higher rigidity than the elastic material constituting the outer peripheral ring 12.

[0022] The width direction of the outer peripheral ring 12 (hereinafter also simply referred to as the width direction) is the direction from the front side to the back side (or from the back side to the front side) of the airless tires 1, 1a, and is the direction along the axis marked with "right" and "left" in the drawings. Extending means that the first reinforcing layer 21 is continuously present in the width direction within a certain range, for example, that the first reinforcing layer 21 is continuously disposed from one end to the other end of the outer peripheral ring 12 in the width direction. The end of the first reinforcing layer 21 may be present inward in the width direction by a first predetermined distance (for example, a distance of 0.1 to 10% of the tire width).

[0023] Fig. 4B is a cross-sectional view of a main part showing an example of an outer peripheral ring 12 different from the outer peripheral ring 12 shown in Fig. 4A, and is a cross-sectional view of a main part showing the tread 14, the outer peripheral ring 12, and the second spoke ring 16 in a cross section perpendicular to the circumferential direction of the airless tire 1a, as in Fig. 4A. The outer peripheral ring 12 shown in Fig. 4B has, in addition to the first reinforcing layer 21, a second reinforcing layer 22 arranged on the inner circumferential side of the first reinforcing layer 21, and a third reinforcing layer 23 arranged on the outer circumferential side of the first reinforcing layer 21.

[0024] The second reinforcing layer 22 and the third reinforcing layer 23 are reinforcing layers containing reinforcing fiber materials such as steel cords, nylon cords, and aramid cords, have higher rigidity than the first reinforcing layer 21, and reinforce the tread 14 together with the first reinforcing layer 21. The second reinforcing layer 22 and the third reinforcing layer 23 are provided in the outer peripheral ring 12, like the first reinforcing layer 21, and extend in the width direction of the outer peripheral ring 12. The number and arrangement of the reinforcing fiber materials can be appropriately set according to the required specifications of the airless tire 1. Note that the outer peripheral ring 12 may include either the second reinforcing layer 22 or the third reinforcing layer 23.

[0025] As an example of the configuration of the reinforcing layer in the outer peripheral ring, the entire reinforcing layer is made of the same hard rubber, and the thickness in the width direction is set to be uniform. An outer peripheral ring having such a reinforcing layer is shown in Fig. 9. Fig. 9 is a cross-sectional view of a main part showing an example of an outer peripheral ring according to a comparative example of the present invention, and shows the outer peripheral ring in a cross section perpendicular to the circumferential direction of the airless tire. The outer peripheral ring 12x shown in Fig. 9 has a reinforcing layer 21x whose entirety is made of the same hard rubber and has a uniform thickness tx.

[0026] When an airless tire having an outer peripheral ring 12x shown in FIG. 9 is mounted on a standard vehicle, the tire ground pressure (unit: MPa) is measured as shown in the lower part of FIG. 9, for example. The ground pressure shown in FIG. 9 is higher at the ends in the width direction due to the bending moment at the ends of the outer peripheral ring 12x, while it is lower at the center in the width direction than at the ends. In this way, when the ground pressure at the ends of the contact surface becomes higher than the ground pressure at the center of the contact surface, the ends of the tread pattern of the tread 14 wear extremely, resulting in uneven wear. In addition, when the ground pressure at the center of the contact surface is relatively low, rainwater easily enters the contact surface from the center of the contact surface, making hydroplaning more likely to occur.

[0027] The tire contact pressure is determined, for example, by the following formula.

number

[0028] In the above formula 1, P indicates the ground pressure of the tire, G indicates the shear modulus of the material constituting the reinforcing layer, H indicates the thickness of the reinforcing layer, and R indicates the radius of curvature from the center of rotation of the tire to the outer circumferential surface of the reinforcing layer. According to the above formula 1, the desired ground pressure (P) can be obtained for each position in the width direction by appropriately setting the shear modulus of the material (G), the thickness (H) of the reinforcing layer, and the radius of curvature (R) from the center of rotation for each position in the width direction. Therefore, in the first reinforcing layer 21 of this embodiment, in order to suppress uneven wear and hydroplaning, the material and shape of the first reinforcing layer 21 are set so that the product of the shear modulus of the material (G) and the thickness (H) differs depending on the position in the width direction in a cross section perpendicular to the circumferential direction (i.e., the cross section shown in Figs. 4A and 4B).

[0029] For example, the shear modulus of elasticity (G) of the material, the thickness (H) of the reinforcing layer, and the radius of curvature (R) from the center of rotation are appropriately set for each position in the width direction, so that the product of the shear modulus of elasticity and the thickness is made larger at the center in the width direction of the first reinforcing layer 21 than at the end of the first reinforcing layer 21. The center is a range from the center in the width direction of the first reinforcing layer 21 to a position that is a second predetermined distance away from the center along the width direction, and the end is a range from the edge of the first reinforcing layer 21 to a position that is a third predetermined distance away from the edge along the width direction. The second predetermined distance and the third predetermined distance can be set as appropriate within a range in which the center and the end do not overlap, and are, for example, distances of 10 to 40% of the tire width.

[0030] As an example, the shear modulus is made larger at the center in the width direction of the first reinforcing layer 21 than at the ends of the first reinforcing layer 21. Fig. 5 is a cross-sectional view of a main part showing an example of the outer peripheral ring 12 according to this embodiment, and shows a cross section perpendicular to the circumferential direction of the airless tire 1a in Fig. 2. The outer peripheral ring 12 shown in Fig. 5 has the first reinforcing layer 21 extending across both ends of the outer peripheral ring 12, and the thickness H1 is uniform in the width direction. The thickness of the first reinforcing layer 21 is the length in the direction perpendicular to the width direction of the first reinforcing layer 21 in a cross section perpendicular to the circumferential direction.

[0031] The first reinforcing layer 21 shown in FIG. 5 is made of two types of hard rubber 21a and 21b, and the shear modulus of the hard rubber 21a is greater than that of the hard rubber 21b. Therefore, the shear modulus is greater in the center of the width direction of the first reinforcing layer 21 (the portion from position P1 to position P2 in FIG. 5) than in the end portions of the first reinforcing layer 21 (the portion from position Pa to position P1 and the portion from position P2 to position Pb). In other words, the product of the shear modulus and the thickness is greater in the portion from position P1 to position P2 than in the portion from position Pa to position P1 and the portion from position P2 to position Pb. Note that positions Pa and Pb shown in FIG. 5 correspond to the edges of the first reinforcing layer 21.

[0032] As another example, the thickness of the first reinforcing layer 21 is made larger at the center in the width direction than at the ends of the first reinforcing layer 21. Fig. 6 is a cross-sectional view of a main part similar to Fig. 5, showing another example of the outer peripheral ring 12 according to this embodiment. The outer peripheral ring 12 shown in Fig. 6 has a first reinforcing layer 21 extending across both ends of the outer peripheral ring 12, and the first reinforcing layer 21 is entirely made of hard rubber 21b. In other words, the shear modulus of elasticity of the first reinforcing layer 21 is uniform in the width direction.

[0033] The first reinforcing layer 21 shown in Fig. 6 has a thickness H2 at the edges (positions Pa and Pb) and a thickness H3 greater than the thickness H2 at the center (position P3). As shown in Fig. 6, the thickness of the first reinforcing layer 21 gradually increases from thickness H2 to thickness H3 between positions Pa and P3, and gradually decreases from thickness H3 to thickness H2 between positions P3 and Pb. Therefore, the product of the shear modulus and thickness is greater at the center of the first reinforcing layer 21 in the width direction than at the ends of the first reinforcing layer 21.

[0034] When the tread 14 has land portions defined by grooves provided along the circumferential direction, the shear modulus of the material (G), the thickness (H) of the reinforcing layer, and the radius of curvature (R) from the center of rotation are appropriately set for each position in the width direction, so that the product of the shear modulus and the thickness is larger at the position corresponding to the center of the width direction of the land portion than at the position corresponding to the end of the land portion. An example of a case where the tread 14 has grooves is shown in FIG. 7. FIG. 7 is a cross-sectional view of a main part similar to FIG. 5, showing yet another example of the outer peripheral ring 12 according to this embodiment. The outer peripheral ring 12 shown in FIG. 7 has a first reinforcing layer 21 extending across both ends of the outer peripheral ring 12, and its thickness H1 is uniform in the width direction.

[0035] The tread 14 shown in Fig. 7 has grooves 31, 32 provided along the circumferential direction, and land portions 41, 42, 43 partitioned by the grooves 31, 32. The grooves 31, 32 do not come into contact with the road surface, so the ground pressure is zero in the portions corresponding to the grooves 31, 32 (i.e., the portion from position P6 to position P7 and the portion from position P10 to position P11). The land portions 41, 42, 43 are portions of the outer circumferential surface of the tread 14 that come into contact with the road surface, and ground pressure is generated in the portions corresponding to the land portions 41, 42, 43 (i.e., the portion from position Pa to position P6, the portion from position P7 to position P10, and the portion from position P11 to position Pb).

[0036] The first reinforcing layer 21 shown in Fig. 7 is made of two types of hard rubber 21a, 21b, similar to the first reinforcing layer 21 shown in Fig. 5, and the shear modulus of the hard rubber 21a is greater than the shear modulus of the hard rubber 21b. In the first reinforcing layer 21 shown in Fig. 7, the hard rubber 21a is disposed at positions corresponding to the centers of the land portions 41, 42, 43 in the width direction (i.e., the portions from position P4 to position P5, the portions from position P8 to position P9, and the portions from position P12 to position P13). Therefore, in the first reinforcement layer 21 shown in Figure 7, the product of the shear modulus and thickness is greater at a position corresponding to the widthwise center of the land portion than at the positions corresponding to the ends of the land portion (i.e., the portion from position Pa to position P4, the portion from position P5 to position P6, the portion from position P7 to position P8, the portion from position P9 to position P10, the portion from position P11 to position P12, and the portion from position P13 to position Pb).

[0037] In addition, when the tread 14 has a plurality of grooves 31, 32 provided along the circumferential direction, the shear modulus at a position corresponding to between the plurality of grooves 31, 32 in the width direction may be made larger than the shear modulus at a position corresponding to the outside of the outermost groove 31, 32 among the plurality of grooves 31, 32. For example, in the first reinforcing layer 21 shown in FIG. 7, by disposing the hard rubber 21a at a position corresponding to between the plurality of grooves 31, 32 (i.e., the portion from position P7 to position P10), the shear modulus at the position corresponding to between the plurality of grooves 31, 32 is made larger than the position corresponding to the outside of the outermost groove 31, 32 among the plurality of grooves 31, 32 (i.e., the portion from position Pa to position P6 and the portion from position P11 to position Pb).

[0038] The thickness of the first reinforcing layer 21 at a position that is on the outer side of the vehicle when the airless tire 1, 1a is mounted on the vehicle may be smaller than the thickness at a position that is on the inner side of the vehicle when the airless tire 1, 1a is mounted on the vehicle. Fig. 8 is a cross-sectional view of a main part similar to Fig. 5, showing yet another example of the outer peripheral ring 12 according to this embodiment. The outer peripheral ring 12 shown in Fig. 8 has a first reinforcing layer 21 that extends across both ends of the outer peripheral ring 12, and the first reinforcing layer 21 is entirely made of hard rubber 21b. In other words, the shear modulus of elasticity of the first reinforcing layer 21 is uniform in the width direction.

[0039] The first reinforcing layer 21 shown in Fig. 8 has a thickness H4 at one edge (position Pa) and a thickness H5 greater than the thickness H4 at the other edge (position Pb). If the position Pa side is the outer side of the vehicle and the position Pb side is the inner side of the vehicle when the airless tire 1, 1a is mounted on a vehicle, the thickness H4 at the position Pa that is the outer side of the vehicle when mounted on the vehicle is smaller than the thickness H5 at the position Pb that is the inner side of the vehicle when mounted on the vehicle in the first reinforcing layer 21 shown in Fig. 8. Therefore, when the airless tire 1, 1a including the outer circumferential ring 12 shown in Fig. 8 is mounted on a vehicle, the radius of curvature is smaller on the outer side of the vehicle than on the inner side of the vehicle by a distance corresponding to the difference between the thickness H5 and the thickness H4.

[0040] [Function of the outer ring] When the airless tire 1, 1a having the outer peripheral ring 12 shown in Figures 5 and 6 is mounted on a standard vehicle, the tire ground contact pressure is measured as shown in the lower part of Figures 5 and 6. As shown in Figures 5 and 6, by making the product of the shear modulus and thickness larger in the central part of the first reinforcing layer 21 than at the ends of the first reinforcing layer 21, the ground contact pressure becomes higher in the central part in the width direction (for example, the part between position P1 and position P2 in Figure 5) than at the ends (for example, the part from position Pa to position P1 and the part from position P2 to position Pb in Figure 5), and the hydroplaning phenomenon can be suppressed.

[0041] When the airless tire 1, 1a having the outer circumferential ring 12 shown in FIG. 7 is mounted on a standard vehicle, the tire ground pressure as shown in the lower part of FIG. 7 is measured. As shown in FIG. 7, the difference in ground pressure between the center and the end of each land portion 41, 42, 43 can be suppressed from increasing, and uneven wear at the end of the land portion 41, 42, 43 can be suppressed. The center of the land portion 41, 42, 43 is a range from the center in the width direction of the land portion 41, 42, 43 to a position that is a fourth predetermined distance away from the center along the width direction, and the end is a range from the edge of the land portion 41, 42, 43 to a position that is a fifth predetermined distance away from the edge along the width direction. The fourth predetermined distance and the fifth predetermined distance can be set as appropriate within a range in which the center and the end do not overlap, and are, for example, 10 to 40% of the width of the land portion.

[0042] When an airless tire 1, 1a having an outer peripheral ring 12 shown in Fig. 8 is mounted on a standard vehicle, the tire ground contact pressure is measured as shown in the lower part of Fig. 8, for example. As shown in Fig. 8, when the airless tire 1, 1a is mounted on a vehicle, the radius of curvature is smaller at position Pa on the outer side of the vehicle than at position Pb on the inner side of the vehicle, and therefore the ground contact pressure is higher. Therefore, even if a camber angle is imparted to the airless tire 1, 1a and the contact area is smaller at position Pa on the outer side of the vehicle than at position Pb on the inner side of the vehicle, the airless tire 1, 1a can reliably come into contact with the road surface.

[0043] [Embodiments of the present invention] According to this embodiment, an airless tire 1 is provided, which includes a plurality of elastic spokes 13 arranged radially from the outer periphery of a wheel 11 coupled to a vehicle toward the inner periphery of an outer periphery ring 12 arranged on the outside of the wheel 11, and the outer periphery ring 12 extends in the width direction of the outer periphery ring 12 and has a first reinforcing layer 21 in which the product of the shear modulus and the thickness varies depending on the position in the width direction in a cross section perpendicular to the circumferential direction of the wheel 11. This makes it possible to suppress changes in tire performance accompanying rotation.

[0044] In the airless tires 1, 1a of the present embodiment, in the width direction, the area of ​​the central portion of the first reinforcing layer 21 is larger than the area of ​​the end portions of the first reinforcing layer 21. This makes it possible to suppress the occurrence of hydroplaning.

[0045] The airless tire 1, 1a of this embodiment includes a tread 14 that is joined to the outer circumferential side of the outer circumferential ring 12 and comes into contact with the road surface, the tread 14 has land portions 41, 42, 43 partitioned by grooves 31, 32 provided along the circumferential direction, and the area at positions corresponding to the centers of the land portions 41, 42, 43 in the width direction is larger than the area at positions corresponding to the ends of the land portions 41, 42, 43. This makes it possible to suppress uneven wear of the land portions 41, 42, 43.

[0046] In the airless tires 1, 1a of the present embodiment, the shear modulus of the central portion of the first reinforcing layer 21 in the width direction is greater than the shear modulus of the end portions of the first reinforcing layer, thereby making it possible to suppress the occurrence of hydroplaning.

[0047] The airless tire 1, 1a of this embodiment includes a tread 14 that is joined to the outer circumferential side of the outer ring 12 and comes into contact with the road surface, the tread 14 has a plurality of grooves 31, 32 provided along the circumferential direction, and the shear modulus at positions corresponding to between the plurality of grooves 31, 32 in the width direction is greater than the shear modulus at positions corresponding to the outside of the outermost groove 31, 32 among the plurality of grooves 31, 32. This increases the ground contact pressure in the center in the width direction, making it possible to suppress the occurrence of hydroplaning.

[0048] In the airless tires 1, 1a of the present embodiment, the thickness of the central portion of the first reinforcing layer 21 in the width direction is greater than the thickness of the end portions of the first reinforcing layer, thereby making it possible to suppress the occurrence of hydroplaning.

[0049] In the airless tires 1, 1a of the present embodiment, the outer ring 12 has a second reinforcing layer 22 disposed on the inner circumferential side of the first reinforcing layer 21, and a third reinforcing layer 23 disposed on the outer circumferential side of the first reinforcing layer 21. This makes it possible to further reinforce the tread 14.

[0050] In the airless tire 1, 1a of the present embodiment, the thickness at a position that is on the outer side of the vehicle when mounted on the vehicle is smaller than the thickness at a position that is on the inner side of the vehicle when mounted on the vehicle. This allows the airless tire 1, 1a to reliably make contact with the road surface even when a camber angle is applied to the airless tire 1, 1a. [Explanation of symbols]

[0051] 1,1a…Airless tires 11…Wheels 12...Outer ring 13…Spokes 14…Tread 15…1st spoke ring 16…2nd spoke ring 21…First reinforcing layer 21a, 21b...Hard rubber 22…Second reinforcing layer 23…Third reinforcing layer 12x…Outer ring (comparison example) 21x: Reinforcement layer (comparison example) 31,32…Groove 41,42,43…Land department H1, H2, H3, H4, H5, Hx…Thickness P1,P2,P3,P4,P5,P6,P7,P8,P9,P10,P11,P12,P13,Pa,Pb...Position

Claims

1. The wheel has a plurality of elastic spokes arranged radially from an outer periphery of a wheel coupled to a vehicle toward an inner periphery of an outer periphery ring disposed on the outside of the wheel, The outer ring has a first reinforcing layer extending in a width direction of the outer ring, and in a cross section perpendicular to a circumferential direction of the wheel, the product of a shear modulus and a thickness varies depending on a position in the width direction.

2. The airless tire according to claim 1 , wherein the area of ​​a central portion of the first reinforcing layer is larger than the area of ​​an end portion of the first reinforcing layer in the width direction.

3. A tread is joined to an outer peripheral side of the outer ring and comes into contact with a road surface, The tread has land portions defined by grooves provided along the circumferential direction, The airless tire according to claim 1 or 2, wherein the product at a position corresponding to a center portion of the land portion in the width direction is larger than the product at a position corresponding to an end portion of the land portion.

4. 3. The airless tire according to claim 1, wherein the shear modulus of elasticity of a central portion of the first reinforcing layer is greater than the shear modulus of elasticity of an end portion of the first reinforcing layer in the width direction.

5. A tread is joined to an outer peripheral side of the outer ring and comes into contact with a road surface, The tread has a plurality of grooves provided along the circumferential direction, 3. The airless tire according to claim 1, wherein the shear modulus at positions corresponding to spaces between the plurality of grooves in the width direction is greater than the shear modulus at positions corresponding to positions outside an outermost groove among the plurality of grooves.

6. 3. The airless tire according to claim 1, wherein the thickness of a central portion of the first reinforcing layer is greater than the thickness of an end portion of the first reinforcing layer in the width direction.

7. 3. The airless tire according to claim 1, wherein the outer ring has a second reinforcing layer disposed on an inner peripheral side of the first reinforcing layer, and a third reinforcing layer disposed on an outer peripheral side of the first reinforcing layer.

8. 3. The airless tire according to claim 1, wherein the thickness at a position that is on an outer side of the vehicle when mounted on the vehicle is smaller than the thickness at a position that is on an inner side of the vehicle when mounted on the vehicle.

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