Airless tires

Abstract

To provide an airless tire capable of providing excellent riding comfort and simultaneously maintaining a vehicle attitude favorably.SOLUTION: An airless tire 1 comprises: an inner cylinder part 31 connected with the outer peripheral surface of a wheel part 2; an outer cylinder part 33 connected with the inner peripheral surface of an outer peripheral ring part 4; and a connection member 32 elastically connecting the inner cylinder part 31 to the outer cylinder part 33. A load-flexure diagram of the airless tire 1 indicates the relation of a load acting to the wheel part 2 in a direction orthogonal to a tire rotary shaft, to a flexure amount of the airless tire 1 specified as the displacement magnitude of a wheel center 2a. In this airless tire, KC is larger than KB when representing the gradient of a load-flexure diagram of the tire in a first load area as KB, and representing that of the tire in a second load area larger than the first area as KC.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an airless tire. [Background technology]

[0002] For example, Patent Document 1 discloses an airless tire that includes a mounting body attached to an axle, a ring-shaped body surrounding the mounting body from the outside in the tire radial direction, and an elastic connector that supports the mounting body and the ring-shaped body so that they can be displaced. The elastic connector is made of a synthetic resin material, and a metallic reinforcing member is embedded in the elastic connector. Patent Document 1 discloses that the strength of the elastic connector can be adjusted by the reinforcing member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6619552 Summary of the Invention [Problem to be solved by the invention]

[0004] The vertical spring constant of an airless tire is strongly influenced by the mechanical properties of the elastic connectors. However, conventional airless tires have not been able to achieve both of the goals of improving ride comfort in a certain load range and maintaining vehicle posture in a load range larger than this load range.

[0005] The present invention has been made in consideration of the above problems, and has an object to provide an airless tire that can achieve both improved ride comfort and maintenance of vehicle posture. [Means for solving the problem]

[0006] An airless tire according to one embodiment of the present invention has an inner tube portion coupled to an outer peripheral surface of a wheel portion, an outer tube portion coupled to an inner peripheral surface of an outer ring portion, and a connecting member that elastically connects the inner tube portion and the outer tube portion. A tire load-deflection diagram shows the relationship between the load acting on the wheel portion and the tire deflection amount specified as the displacement amount of the wheel center. If the gradient of the tire load-deflection diagram in a first load range is KB and the gradient of the tire load-deflection diagram in a second load range larger than the first load range is KC, KC is larger than KB. Effect of the Invention

[0007] According to the present invention, it is possible to improve the ride comfort while maintaining the vehicle posture. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a side view showing an airless tire. [Diagram 2] FIG. 2 is a perspective cross-sectional view showing a main part of the airless tire shown in FIG. [Diagram 3] FIG. 3 is a cross-sectional view that illustrates a schematic configuration of the elastic connector. [Figure 4] FIG. 4 is an explanatory diagram showing the relationship between the load acting on an airless tire and the amount of deflection. [Diagram 5] FIG. 5 is a diagram showing a load-deflection diagram of an airless tire. [Figure 6] FIG. 6 is a diagram showing a stress-strain diagram of the main member, which shows the relationship between stress and strain when a tensile load acts on the main member. [Figure 7] FIG. 7 is a cross-sectional view showing an elastic connector according to a modified example. [Figure 8] FIG. 8 is a cross-sectional view showing an elastic connector according to a modified example. [Figure 9] FIG. 9 is a cross-sectional view showing the state of stress acting on the elastic connector in a compressed state. [Figure 10] FIG. 10 is a cross-sectional view showing the state of stress acting on the elastic connector in a tensile state. [Figure 11] FIG. 11 is a cross-sectional view showing an elastic connector according to a modified example. [Figure 12] FIG. 12 is a cross-sectional view showing an elastic connector according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the description of the drawings, the same parts are given the same reference numerals and the description will be omitted.

[0010] The configuration of an airless tire 1 according to this embodiment will be described with reference to Fig. 1 and Fig. 2. The airless tire 1 has a wheel portion 2, an elastic connector 3, and an outer circumferential ring portion 4. Note that the wheel portion 2 is omitted in Fig. 2.

[0011] The wheel portion 2 has a disk shape. The wheel portion 2 is a member to which an axle of a vehicle is connected, and is fixed to the axle via a hub by fastening means such as a bolt. The axle is fixed to the wheel center of the wheel portion 2. The wheel center corresponds to the rotation axis of the airless tire 1. The wheel portion 2 is made of a metal material such as an aluminum alloy.

[0012] The elastic connector 3 is disposed radially outward of the wheel portion 2 and radially inward of the outer circumferential ring portion 4. The elastic connector 3 serves to connect the wheel portion 2 and the outer circumferential ring portion 4. The elastic connector 3 is formed from an elastically deformable material such as resin or rubber. The elastic deformation of the elastic connector 3 enables the airless tire 1 to support the weight of the vehicle and absorb impacts input from the ground.

[0013] The elastic connector 3 has an inner cylinder portion 31, a plurality of connecting members 32, and an outer cylinder portion 33. The inner cylinder portion 31, the plurality of connecting members 32, and the outer cylinder portion 33 are integrally formed.

[0014] The inner cylinder portion 31 is disposed radially outward of the wheel portion 2. The inner cylinder portion 31 has a cylindrical shape, and an inner peripheral surface of the inner cylinder portion 31 is coupled to an outer peripheral surface of the wheel portion 2.

[0015] The multiple connecting members 32 are arranged at intervals in the tire circumferential direction and extend radially along the tire radial direction. Each connecting member 32 elastically connects the inner tube portion 31 and the outer tube portion 33. The outer end of the connecting member 32 in the tire radial direction is connected to the inner peripheral surface of the outer tube portion 33, and the inner end of the connecting member 32 in the tire radial direction is connected to the outer peripheral surface of the inner tube portion 31.

[0016] A space is formed between a pair of connecting members 32 adjacent in the tire circumferential direction, the inner cylinder portion 31, and the outer cylinder portion 33, and this space communicates in the tire rotation axis direction. The space may be filled with a material different from the material forming the elastic connecting body 3.

[0017] The outer tubular portion 33 is disposed radially inward of the outer circumferential ring portion 4. The outer tubular portion 33 has a cylindrical shape, and an outer circumferential surface of the outer tubular portion 33 is joined to an inner circumferential surface of the outer circumferential ring portion 4.

[0018] When connecting the inner cylindrical portion 31 and the outer cylindrical portion 33, the structure is not limited to a structure in which a plurality of connecting members 32 are provided radially. It may be a cellular type having a honeycomb structure, or a void structure having a non-radial shape.

[0019] The outer circumferential ring portion 4 is concentrically disposed on the outer side of the wheel portion 2 in the tire radial direction, separated by the elastic connecting body 3. The outer circumferential ring portion 4 has a cylindrical shape, and the outer circumferential surface of the outer circumferential ring portion 4 becomes a contact surface that comes into contact with the ground.

[0020] The outer ring portion 4 contains a base material made of a material such as rubber and reinforcing fibers such as steel cords contained within the base material in order to support the load input to the wheel portion 2. A groove pattern called a tread pattern is engraved on the outer circumferential surface of the outer ring portion 4.

[0021] The wheel portion 2 and the inner cylinder portion 31, and the outer cylinder portion 33 and the outer ring portion 4 are joined by, for example, an adhesive. However, the joining method is not limited to this, and may be a mechanical type, a fitting type, or the like.

[0022] The airless tire 1 configured as described above is fixed to an axle via a hub provided on a vehicle. A force (driving force or braking force) generated on the vehicle side is transmitted to the ground via the wheel portion 2, the elastic connector 3, and the outer peripheral ring portion 4. When the airless tire is steered, a deviation between the tire traveling direction and the tire center direction causes the outer peripheral ring portion 4 to generate a force (lateral force) in the tire rotation axis direction (tire width direction).

[0023] Fig. 3 shows a schematic cross-sectional structure of the connecting member 32 as viewed from the tire rotation axis direction. The up-down direction of the paper in Fig. 3 corresponds to the tire radial direction, with the upper side of the paper corresponding to the outer side in the tire radial direction and the lower side of the paper corresponding to the inner side in the tire radial direction. Ro indicates the radius from the tire rotation center to the inner circumferential surface 33a of the outer tubular portion 33 (hereinafter referred to as the "inner diameter of the outer tubular portion 33"). Ri indicates the radius from the tire rotation center to the outer circumferential surface 31a of the inner tubular portion 31 (hereinafter referred to as the "outer diameter of the inner tubular portion 31").

[0024] A description will be given of the structure of the connecting member 32 constituting the elastic connector 3. In the following description, one connecting member 32 out of the multiple connecting members 32 constituting the elastic connector 3 will be illustrated, but the same applies to the other connecting members 32.

[0025] The connecting member 32 is composed of a main member 32a and a reinforcing member 32b. In the example shown in Fig. 3, the reinforcing member 32b is included inside the main member 32a and is integrated with the main member 32a. The reinforcing member 32b is disposed so as to be aligned with a neutral line passing through the center of the connecting member 32 when viewed from the tire rotational axis direction.

[0026] The relationship between the load acting on an airless tire and the amount of deflection will be described with reference to FIG. 4. In an airless tire 1, a load acts on the wheel section 2 to which the axle is fixed. A load acts on the wheel section 2 in a direction perpendicular to the tire rotation axis. Typically, a vertical load that presses the wheel section 2 toward the ground acts on the wheel section 2. When the ground is a horizontal surface, a vertical load corresponds to a vertical load. When a load acts on the wheel section 2, the wheel center 2a, which is the center of the wheel section 2, moves vertically downward. The amount of displacement of the wheel center 2a when a load is acting on the wheel section 2 is the amount of deflection D1 of the airless tire 1, based on the wheel center 2a when no load is acting on the wheel section 2.

[0027] The load-deflection diagram of the airless tire 1 will be described with reference to FIG. 5. The load-deflection diagram of the airless tire 1 shows the relationship between the vertical load acting on the wheel portion 2 and the amount of deflection of the airless tire 1, which is specified as the amount of displacement of the wheel center. As shown in FIG. 5, the load-deflection diagram of the airless tire 1 has a different gradient depending on the load range acting on the wheel portion 2. In the load-deflection diagram of the airless tire 1, the gradient in the low load range (third load range) from zero to load F1 is KA, and the gradient in the medium load range (first load range) from load F1 to load F2 is KB. Moreover, the gradient in the high load range (second load range) of loads F2 and above is KC.

[0028] Of the three load ranges mentioned above, the low load range is a load range that includes no load (zero load). The medium load range is a load range that includes the design standard load Fa, and the high load range is a load range that includes the maximum load Fb. The design standard load Fa is a load that is designed in advance assuming that the vehicle is traveling at a constant speed on a flat road surface, and is defined based on the vehicle specifications, etc. The maximum load Fb is a load that is designed in advance assuming the maximum load when the vehicle is used, and is defined based on the vehicle specifications, etc.

[0029] In this way, the load-deflection diagram of the airless tire 1 has nonlinear characteristics and is a curve with at least two bends. The gradients KA, KB, and KC in each load range have a relationship in which KA is larger than KB, and KC is larger than KB. In other words, the following relationship holds for the gradients KA, KB, and KC in each load range. KC>KB, KA>KB

[0030] Since the gradient KB at the design standard load Fa is small, the vertical spring constant at the design standard load Fa is small, and the ride comfort can be improved. On the other hand, since the gradient KC at the maximum load Fb is large, the rigidity of the airless tire 1 at the maximum load Fb is high, and the vehicle posture can be maintained. This makes it possible to achieve both an improvement in ride comfort at the design standard load Fa and maintenance of the vehicle posture at the maximum load Fb.

[0031] 5, the airless tire 1 of this embodiment is designed so that the deflection amount Da corresponding to the maximum load Fb satisfies the following relationship with respect to the maximum deflection amount Db of the airless tire 1. Here, the maximum deflection amount Db of the airless tire 1 corresponds to a value obtained by subtracting the outer diameter Ri of the inner tube portion 31 from the inner diameter Ro of the outer tube portion 33 when no load is applied. Da < 0.5 × Db = 0.5 × (Ro-Ri)

[0032] The nonlinear characteristics of the load-deflection diagram of the airless tire 1 have been described above, but the factors that cause such nonlinear characteristics will now be described. Because the wheel portion 2 and the outer peripheral ring portion 4 have high rigidity, the deflection of the airless tire 1 can be considered as the deflection of the connecting members 32. When a load is applied to the wheel portion 2, the wheel portion 2 moves vertically downward, that is, toward the road surface. At this time, of the multiple connecting members 32, the connecting members 32 located near the contact surface of the outer peripheral ring portion 4 are in a state where a compressive load is applied, while the other connecting members 32 are in a state where a tensile load is applied.

[0033] Therefore, the characteristics of the non-pneumatic tire 1 are strongly reflected in the mechanical characteristics when a load acts on the connecting member 32. In the present embodiment, by configuring the connecting member 32 with the main member 32a and the reinforcing member 32b, a load-deflection diagram of the non-pneumatic tire 1 having the non-linearity characteristics shown in FIG. 5 is realized. Hereinafter, details of the main member 32a and the reinforcing member 32b will be described.

[0034] The main member 32a and the reinforcing member 32b have different longitudinal elastic coefficients from each other, and the longitudinal elastic coefficient of the reinforcing member 32b is set to be larger than the longitudinal elastic coefficient of the main member 32a. Further, the reinforcing member 32b has a characteristic that the rigidity against a compressive load is lower than the rigidity against a tensile load, and more preferably, the rigidity on the compression side is substantially zero.

[0035] Specifically, the main member 32a is composed of a material having a longitudinal elastic coefficient smaller than that of the reinforcing member 32b and having non-linearity characteristics. For example, the main member 32a is composed of a resin such as an elastomer such as urethane resin or rubber.

[0036] FIG. 6 is a diagram showing a stress-strain diagram of the main member 32a showing the relationship between stress and strain when a tensile load acts on the main member 32a. The stress-strain diagram of the main member 32a reflects the material characteristics of the main member 32a. When the stress is near zero, the gradient is EA, and when the stress becomes larger than σ1, the gradient changes from EA to EB. Comparing EA and EB, EA is larger than EB (EB < EA). Further, when the stress becomes larger than σ2, the gradient changes from EB to EC. Comparing both EB and EC, EC is larger than EB (EB < EC). When the stress becomes even larger, the main member 32a finally breaks.

[0037] The connecting member 32 utilizes such mechanical properties of the main member 32a. As a result, a relationship in which EA is greater than EB (EA>EB) can be obtained in the stress-strain diagram of the connecting member 32 as well. Then, by setting the gradient of the stress-strain diagram of the connecting member 32 when a load in the small load range acts as a tensile load as EA and the gradient of the stress-strain diagram of the connecting member 32 when a load in the medium load range acts as a tensile load as EB, a gradient relationship in which KA is greater than KB (KA>KB) can be realized in the load-deflection diagram of the airless tire 1. In other words, the gradient relationship (KA>KB) in the load-deflection diagram of the airless tire 1 is realized by using the tensile side rigidity of the connecting member 32.

[0038] Next, the stiffness of the reinforcing member 32b against a compressive load is lower than that against a tensile load, and more specifically, the stiffness on the compression side is approximately zero. For example, a fiber material such as glass fiber or carbon fiber can be used as the reinforcing member 32b having such characteristics. The reinforcing member 32b is configured, for example, in a sheet shape, and its thickness in the tire circumferential direction is smaller than that of the main member 32a. The reinforcing member 32b generates a reaction force only on the tensile side without generating a reaction force on the compression side. If there is no reaction force action on the tensile side of the reinforcing member 32b, the airless tire 1 will continue to bend until it reaches the maximum deflection amount Db. In this case, the vehicle posture will be lost and it will not be able to run.

[0039] The reinforcing member 32b can limit elongation when a tensile load acts on the connecting member 32. By providing the connecting member 32 with the reinforcing member 32b, the rigidity of the tensile side of the connecting member 32 when a tensile load acts on the connecting member 32 can be increased. In other words, if the ratio of the deflection amount of the connecting member 32 when a tensile load acts on the connecting member 32 to the tensile load is defined as the equivalent Young's modulus, the equivalent Young's modulus when a load in the large load range acts as a tensile load can be made larger than the equivalent Young's modulus when a load in the medium load range acts as a tensile load.

[0040] In this embodiment, by utilizing the rigidity of the tensile side of the connecting member 32, a gradient relationship (KC>KB) is realized in which KC is greater than KB in the load-deflection diagram of the airless tire 1. In other words, the vehicle posture can be maintained by limiting the allowable deflection amount of the airless tire 1 with the reinforcing member 32b.

[0041] As described above, according to the airless tire 1 according to this embodiment, the gradient KB in the load-deflection diagram of the airless tire 1 is relatively smaller than the gradient KC. Therefore, in the medium load range, the vertical spring constant of the airless tire 1 is small, and vertical flexibility can be obtained. Since the impact from the road surface is easily absorbed, the ride comfort can be improved. On the other hand, the gradient KC in the load-deflection diagram of the airless tire 1 is relatively larger than the gradient KB. Therefore, when a load in the heavy load range acts, the vertical spring constant of the airless tire 1 is large, and high rigidity can be obtained. As a result, even if a large load such as in the heavy load range acts, the amount of deflection of the airless tire 1 can be suppressed, and the vehicle posture can be maintained. As a result, it is possible to achieve both improved ride comfort and maintenance of the vehicle posture.

[0042] According to the airless tire 1 according to this embodiment, the gradient KB is smaller than the gradient KA of the load-deflection diagram of the airless tire 1. For this reason, in a situation where a certain vertical load acts on the airless tire 1, the vertical spring constant of the airless tire 1 is small, and vertical flexibility can be obtained. As a result, the airless tire 1 can more easily absorb shocks received from the road surface, thereby improving ride comfort.

[0043] In the airless tire 1 according to this embodiment, the gradient EA in the stress-strain diagram of the connecting member 32 is larger than the gradient EB. For this reason, by utilizing the mechanical properties of the connecting member 32, it is possible to reduce the gradient KB in the load-deflection diagram of the airless tire 1. This makes it easier to absorb shocks from the road surface, thereby improving the ride comfort.

[0044] According to the airless tire 1 according to this embodiment, the connecting member 32 is composed of a main member 32a and a reinforcing member 32b. This reinforcing member 32b has low rigidity against a compressive load. Therefore, even if a load is input to the wheel portion 2, the connecting member 32 located near the ground contact surface of the outer circumferential ring portion 4 does not exert a reaction force, so that the airless tire 1 can obtain flexibility in the vertical direction. On the other hand, the reinforcing member 32b has high rigidity against a tensile load. Therefore, when a load is input to the wheel portion 2, the connecting member 32 other than the ground contact surface of the outer circumferential ring portion 4 exerts a reaction force. This makes it possible to suppress the airless tire 1 from bending significantly. As a result, it is possible to achieve both improved ride comfort and maintenance of the vehicle posture.

[0045] According to the airless tire 1 according to this embodiment, the equivalent modulus of longitudinal elasticity of the connecting member 32 when a load in the heavy load range acts as a tensile load is greater than the equivalent modulus of longitudinal elasticity of the connecting member 32 when a load in the medium load range acts as a tensile load. Since the rigidity of the connecting member 32 in the heavy load range is increased, the vehicle posture can be maintained. This makes it possible to achieve both improved ride comfort and maintenance of the vehicle posture.

[0046] Moreover, according to the airless tire 1 according to the present embodiment, the deflection amount Da corresponding to the maximum load Fb satisfies a predetermined relationship (Da<0.5×Db) with respect to the maximum deflection amount Db of the airless tire 1. Since the maximum deflection amount Db at the maximum load Fb can be set, the vehicle posture at the maximum load Fb can be maintained.

[0047] In addition, when the stiff reinforcing member 32b is enclosed in the flexible main member 32a, it is preferable to take measures to prevent peeling at the interface between the main member 32a and the reinforcing member 32b. For example, it is preferable to coat the reinforcing member 32b with an intermediate member that can tolerate shear deformation. A method of sandwiching the reinforcing member 32b with a sheet-like material and coating it may be used, or the surface of the reinforcing member 32b may be coated in advance with a spray or the like.

[0048] The above-described configuration of the connecting member 32 is one example, and various other configurations can be adopted for the connecting member 32. For example, as shown in Fig. 7, the reinforcing member 32b may be independently disposed outside the main member 32a, rather than being configured to be contained within the main member 32a.

[0049] 8, the connecting member 32 may have a curved shape such that the member length L1 is greater than the radial length L0. Here, the member length L1 is the length of the connecting member 32 from the inner tube portion 31 to the outer tube portion 33 along the connecting member 32 when viewed from the tire rotational axis direction. The radial length L0 is the length (straight-line distance) of the connecting member 32 from the inner tube portion 31 to the outer tube portion 33 along the tire radial direction.

[0050] According to the airless tire 1 configured as described above, when the wheel portion 2 is displaced vertically by a certain amount or more, a tensile load acts on the reinforcing member 32b. Therefore, until the wheel portion 2 is displaced vertically by a certain amount, no reaction force is generated in the connecting member 32, and flexibility in the vertical direction can be obtained. On the other hand, when the wheel portion 2 is displaced vertically by a certain amount or more, a tensile load acts on the connecting member 32. This generates rigidity in the connecting member 32, making it possible to maintain the vehicle posture.

[0051] 9 and 10, the main member 32a is divided into a first region 32a1 and a second region 32a2 when viewed from the tire rotational axis direction. The first region 32a1 is a region on the left side of the neutral line of the connecting member 32 in the figure, and is a curved outer region with a convex outer surface. On the other hand, the second region 32a2 is a region on the right side of the neutral line of the connecting member 32 in the figure, and is a curved inner region with a concave outer surface.

[0052] The radial length of the connecting member 32 when no load is applied is defined as L0 (see FIG. 8). When a load is applied to the wheel portion 2 and the connecting member 32 is compressed, the radial length changes from L0 to L2. In this case, in the main member 32a, compressive stress occurs in the second region 32a2, which is the inner region of the bend, and tensile stress occurs in the first region 32a1, which is the outer region of the bend.

[0053] 10, when a load is applied to the wheel portion 2 and the connecting member 32 is in a tensile state, the radial length changes from L0 to L3. In this case, compressive stress is generated in the first region 32a1, which is the outer bend region, and tensile stress is generated in the second region 32a2, which is the inner bend region.

[0054] Considering such a stress state, it is preferable to dispose the reinforcing member 32b in the second region 32a2. This causes the connecting member 32 to generate no reaction force in a compressed state, but generates a tensile reaction force in a tensile state. As a result, the tensile rigidity of the connecting member 32 can be increased. In particular, by disposing the reinforcing member 32b on the outermost side of the second region 32a2, the tensile rigidity can be further increased.

[0055] With the airless tire 1 configured in this way, the reinforcing member 32b can be disposed at an appropriate position. Also, the intersection of the gradient KB of the load-deflection diagram of the airless tire 1 and the gradient KC of the load-deflection diagram of the airless tire 1 moves to the side of larger deflection. This widens the range of the medium load area where the gradient KB is located, and therefore the load area where a comfortable ride is achieved can be expanded.

[0056] 11 and 12, the connecting member 32 may have a composite curved shape having two or more bent portions. In this case, as shown in Fig. 11, focusing on only one bent portion, the reinforcing member 32b may be disposed in a second region (one region bordered by the neutral line of the connecting member 32) corresponding to the bent inner region of the bent portion. Also, as shown in Fig. 12, the reinforcing member 32b may be disposed transversely to the first region and the second region bordered by the neutral line of the connecting member 32 so as to be located in the bent inner region at each bent portion.

[0057] As described above, the embodiment of the present invention has been described, but the description and drawings forming a part of this disclosure should not be understood as limiting this invention. From this disclosure, various alternative embodiments, examples and operating techniques will become apparent to those skilled in the art. [Explanation of symbols]

[0058] 1. Airless tires 2 Wheel section 2a Wheel center 3 Elastic Link 31 Inner cylinder 32 Connecting members 32a Main member 32b Reinforcement member 33 External cylinder 4 Outer ring

Claims

1. a wheel portion to which an axle of a vehicle is fixed relative to a wheel center; An outer circumferential ring portion is disposed radially outward of the wheel portion in the tire radial direction and has a contact surface that comes into contact with the ground; an elastic connector disposed radially outward of the wheel portion and radially inward of the outer circumferential ring portion, the elastic connector connecting the wheel portion and the outer circumferential ring portion, The elastic connector is an inner cylinder portion coupled to an outer circumferential surface of the wheel portion; an outer cylinder portion coupled to an inner peripheral surface of the outer peripheral ring portion; a plurality of connecting members arranged along the tire circumferential direction and elastically connecting the inner tubular portion and the outer tubular portion; The connecting member is composed of a main member and a reinforcing member having different moduli of longitudinal elasticity, The Young's modulus of the reinforcing member is greater than the Young's modulus of the main member, The reinforcing member has a lower rigidity against a compressive load than against a tensile load, In a stress-strain diagram of the main member showing the relationship between stress and strain when a tensile load acts on the main member, if a gradient of the stress-strain diagram of the main member when a load in a third load region smaller than the first load region acts as a tensile load is defined as EA, and a gradient of the stress-strain diagram of the main member when a load in the first load region acts as a tensile load is defined as EB, EA is larger than EB, the reinforcing member limits elongation of the connecting member when a tensile load is applied thereto such that, when the ratio of the amount of deflection of the connecting member when a tensile load is applied to the connecting member and the tensile load is defined as the equivalent longitudinal elastic modulus, the equivalent longitudinal elastic modulus when a load in a second load region larger than that in the first load region acts as a tensile load is greater than the equivalent longitudinal elastic modulus when a load in the first load region acts as a tensile load; a tire load-deflection diagram showing a relationship between a load acting on the wheel portion in a direction perpendicular to a tire rotation axis and a tire deflection amount specified as a displacement amount of the wheel center, wherein, assuming that a gradient of the tire load-deflection diagram in the first load range is KB and a gradient of the tire load-deflection diagram in the second load range is KC, KC is larger than KB; If the gradient of the load-deflection diagram of the tire in the third load range is KA, KA is greater than KB. Airless tires.

2. The thickness of the main member in the tire circumferential direction is greater than the thickness of the reinforcing member in the tire circumferential direction. The airless tire according to claim 1.

3. When viewed from the tire rotational axis direction, a member length of the connecting member from the inner cylinder portion to the outer cylinder portion along the connecting member is greater than a radial length of the connecting member from the inner cylinder portion to the outer cylinder portion along the tire radial direction. The airless tire according to claim 1 or 2.

4. When the connecting member is divided into two regions with a neutral line passing through the center of the connecting member as viewed in the tire rotational axis direction, and when a load is applied to the wheel portion and the radial length of the connecting member is shortened, the region on the side where a compressive stress acts is defined as the second region, and the region on the side where a tensile stress acts is defined as the first region, the reinforcing member is disposed in the second region. The airless tire according to claim 3.

5. The reinforcing member is disposed on the outermost side of the second region. The airless tire according to claim 4.

6. the second load range includes a maximum load defined by specifications of the vehicle, In the load-deflection diagram of the tire, when the deflection amount corresponding to the maximum load is Da, the radius to the outer peripheral surface of the inner cylinder portion when no load is applied to the wheel portion is Ri, and the radius to the inner peripheral surface of the outer cylinder portion is Ro, the following relationship is satisfied: Da < 0.5 × (Ro-Ri) The airless tire according to any one of claims 1 to 5.

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