Airless tire

Abstract

To provide an airless tire that can suppress local deformation when a load is applied in the radial direction of the tire.SOLUTION: An airless tire 1 comprises: a plurality of first spokes 13 arranged radially from an outer periphery of a wheel 11 connected to a vehicle toward an inner periphery of a tread 12 that comes into contact with a road surface; intermediate rings 14 arranged between the wheel 11 and the tread 12 and connecting the plurality of first spokes 13 to each other; and one or more second spokes 15 connecting at least one of between the first spoke 13 and the intermediate ring 14, between the first spoke 13 and the tread 12, and between the intermediate ring 14 and the tread 12.SELECTED DRAWING: Figure 1

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 a base connected to a rigid portion, a deformable structure, and a top that is connected to the tire tread (Patent Document 1). The deformable structure includes a slot that spans the entire width of the tire, a block portion that is inclined relative to the radial direction of the tire and is made up of elements that form a repeating shape in the circumferential direction of the tire, and auxiliary elements that are arranged in the circumferential direction and support one element between two adjacent elements. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 3-208702 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described conventional technology, when a large load is applied in the radial direction of the tire, the block portion deforms significantly, causing a compressive force to act on the auxiliary element in the circumferential direction of the tire, causing the auxiliary element to deform excessively and buckle, resulting in the auxiliary element being unable to transmit the load in the circumferential direction of the tire.

[0005] An object of the present invention is to provide an airless tire that can suppress local deformation when a load is applied in the radial direction of the tire. [Means for solving the problem]

[0006] The present invention solves the above problem by providing, in addition to a plurality of first spokes arranged radially from the outer periphery of the wheel connected to the vehicle toward the inner periphery of the tread that comes into contact with the road surface, and an intermediate ring arranged between the wheel and the tread and connecting the plurality of first spokes to each other, second spokes connecting at least one of the first spokes and the intermediate ring, the first spokes and the tread, and the intermediate ring and the tread. Effect of the Invention

[0007] According to the present invention, it is possible to suppress local deformation when a load is applied in the radial direction of the tire. [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 an enlarged perspective view showing the airless tire of FIG. 1. [Diagram 3] FIG. 2 is an enlarged front view showing a portion A in FIG. [Figure 4] FIG. 2 is a front view illustrating another example of an airless tire according to an embodiment of the present invention. [Diagram 5] FIG. 6 is an enlarged perspective view showing the airless tire of FIG. 5. [Figure 6] 6 is an enlarged front view showing a portion B in FIG. 5. FIG. [Figure 7] FIG. 11 is an enlarged front view showing a modified example of the second spoke of the embodiment. [Figure 8] 5 is an enlarged front view showing the function of the second spoke of the present embodiment. FIG. 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] [First embodiment] Fig. 1 is a front view showing an example of an airless tire according to an embodiment of the present invention, and Fig. 2 is an enlarged perspective view showing the airless tire of Fig. 1. An airless tire is a tire that supports a vehicle body with the reaction force of spokes made of an elastic material (hereinafter also referred to as an elastic material) rather than air pressure. 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 wheels of carts and the like. As shown in Figs. 1 and 2, the airless tire 1 includes a wheel 11, a tread 12, first spokes 13, an intermediate ring 14, and second spokes 15.

[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 materials. As shown in FIG. 2, the wheel 11 is made up of a disk-shaped disc 111 and a cylindrical rim 112. The disc 111 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 111 to the hub of the vehicle. The shape of the wheel 11 can be appropriately set according to the required specifications of the airless tire 1. The disc 111 and the rim 112 may be molded as a single unit, or may be combined after being molded separately.

[0012] The tread 12 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 12 is made of a composite material in which an elastic material such as natural rubber or synthetic rubber is reinforced with a metal or resin tire cord. A tread pattern is formed on the outer periphery of the tread 12, as in conventional pneumatic tires, and forms the contact surface with the road surface. The thickness of the tread 12 and the shape of the tread pattern can be appropriately set according to the required specifications of the airless tire 1.

[0013] The first spokes 13 are members that support a load (e.g., a 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 equivalent to the tire width. The first spokes 13 extend radially from the outer circumferential side of the wheel 11 (specifically, the outer circumferential side of the rim 112) toward the inner circumferential side of the tread 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 first spokes 13 are provided axially symmetrically with respect to the central axis of the airless tire 1. The number of first 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 first spokes 13, vibration resistance, and other required specifications of the airless tire 1.

[0014] The means for attaching the first spokes 13 to the wheel 11 is not particularly limited as long as robustness can be ensured. For example, a groove may be formed in the outer peripheral surface of the rim 112, and the inner peripheral end of the first spoke 13 may be fitted into this groove. The outer peripheral surface of the rim 112 and the inner peripheral end of the first spoke 13 may be bonded with an adhesive, or the outer peripheral surface of the rim 112 and the inner peripheral end of the first spoke 13 may be directly connected with a bolt. Similarly, the means for attaching the first spokes 13 to the tread 12 is not particularly limited as long as robustness can be ensured. For example, the inner peripheral surface of the tread 12 and the outer peripheral end of the first spoke 13 may be bonded with an adhesive.

[0015] The intermediate ring 14 is a member that transmits circumferential deformation of the first spokes 13 to adjacent first spokes 13 in order to support the load with the entire airless tire 1 when the first spokes 13 are deformed due to a radial load. The intermediate ring 14 has a cylindrical shape concentric with the wheel 11 and the tread 12, and is provided between the wheel 11 and the tread 12 to connect the multiple first spokes 13 to each other. The airless tire 1 shown in Figures 1 and 2 has five intermediate rings 14, but the number of intermediate rings 14 provided in one airless tire 1 is not particularly limited.

[0016] Like the first spokes 13, the intermediate ring 14 is made of an elastic material such as an elastic thermoplastic resin or an elastic thermosetting resin. There are no particular limitations on the means for attaching the intermediate ring 14 to the first spokes 13 as long as robustness can be ensured. For example, the intermediate ring 14 may be bonded to the first spokes 13 with an adhesive. Alternatively, the first spokes 13 and the intermediate ring 14 may be integrally molded.

[0017] The second spokes 15 are members that suppress deformation of the intermediate ring 14 due to radial loads, and are made of an elastic material such as an elastic thermoplastic resin or an elastic thermosetting resin, like the first spokes 13 and the intermediate ring 14. The shape (particularly the thickness) of the second spokes 15 can be appropriately set within a range in which deformation of the intermediate ring 14 can be suppressed.

[0018] The second spokes 15 are provided at positions that suppress deformation of the intermediate ring 14 itself or suppress deformation of a member that affects the deformation of the intermediate ring 14. Specifically, the second spokes 15 are provided by connecting at least one of (a) the first spokes 13 and the intermediate ring 14, (b) the first spokes 13 and the tread 12, and (c) the intermediate ring 14 and the tread 12. In addition, when the airless tire 1 includes a plurality of intermediate rings 14, the second spokes 15 may (d) connect the intermediate rings 14 together. The second spokes 15 of (a), (c), and (d) suppress deformation of the intermediate ring 14 itself, and the second spoke 15 of (b) suppresses deformation of the first spokes 13 that affects the deformation of the intermediate ring 14.

[0019] The means for attaching the second spokes 15 to the first spokes 13 and the intermediate ring 14 is not particularly limited as long as robustness can be ensured. For example, the second spokes 15 may be bonded to the first spokes 13 and the intermediate ring 14 with an adhesive. The first spokes 13, the intermediate ring 14, and the second spokes 15 may be integrally molded. The means for attaching the second spokes 15 to the tread 12 is not particularly limited as long as robustness can be ensured. For example, the inner circumferential surface of the tread 12 and the outer circumferential end of the second spoke 15 may be bonded with an adhesive.

[0020] When the airless tire 1 has a single intermediate ring 14, the second spokes 15 may be provided between the intermediate ring 14 and the tread 12, and when the airless tire 1 has a plurality of intermediate rings 14, the second spokes 15 may be provided between the radially outermost intermediate ring 14 and the tread 12. In other words, the second spokes 15 may connect at least one of the first spokes 13 and the tread 12, and the intermediate ring 14 and the tread 12. This makes it possible to suppress deformation of the outermost intermediate ring 14, which is most deformed when a radial load is applied. For example, in the airless tire 1 shown in FIGS. 1 and 2, the second spokes 15 connect the outermost intermediate ring 14 and the tread 12.

[0021] FIG. 3 is an enlarged front view showing an enlarged A portion of FIG. 1, and five intermediate rings 14a, 14b, 14c, 14d, and 14e are provided between the rim 112 and the tread 12. As shown in FIG. 3, the first spoke 13b has a plurality of bent portions 21, 22, 23, 24, and 25 between the end portion 131 on the wheel 11 side and the end portion 132 on the tread 12 side, which are bent (i.e., bent in the circumferential direction) in a direction connecting these two ends 131 and 132 (i.e., in the radial direction). As shown in FIG. 3, the intermediate rings 14a, 14b, 14c, 14d, and 14e may be connected to the bent portions 21, 22, 23, 24, and 25, respectively. In addition, the thickness of the tread 12 may be half or less of the radial distance between the bent portions. For example, in the airless tire 1 shown in FIG. 3, the thickness of the tread 12 is half or less of the radial distance L between the bent portions 21 and 22.

[0022] If the degree of bending of the bent portions 21, 22, 23, 24, and 25 of the first spoke 13b is extremely small, the first spoke 13b will buckle between the bent portions 21, 22, 23, 24, and 25, making it impossible to restrict the amount of deformation in the circumferential direction. For this reason, it is desirable to set the minor angle θ of the bent portions 21, 22, 23, 24, and 25 shown in Fig. 3 to less than 120°. Note that although the reference numerals for the bent portions 21, 22, 23, 24, and 25 are only attached to the first spoke 13b shown on the right side of Fig. 3, bent portions of the same configuration are formed in each of the first spokes 13 around the entire circumference of the airless tire 1.

[0023] In the airless tire 1 shown in Fig. 3, the bent portions of the first spokes 13 connected to the same intermediate rings 14a, 14b, 14c, 14d, and 14e are formed so as to bend in the same direction relative to the circumferential direction. That is, as shown in Fig. 3, in the intermediate ring 14a provided on the innermost side, the bending directions of the bent portions 21a and 21 of the two first spokes 13a and 13b connected to the intermediate ring 14a are both convex to the left in Fig. 3. Similarly, the bending directions of the bent portions of the two first spokes 13a and 13b connected to the intermediate rings 14c and 14e are both convex to the left in Fig. 3, and the bending directions of the bent portions of the two first spokes 13a and 13b connected to the intermediate rings 14b and 14d are both convex to the right in Fig. 3.

[0024] If the bent portions of the first spokes 13 connected to the same intermediate ring 14 are formed so as to bend in the same direction relative to the circumferential direction of the tire (i.e., the zigzags of the first spokes 13 are set in phase), the direction of deformation in the circumferential direction of the bent portions of the first spokes 13 will be the same for adjacent first spokes 13. This makes the axial force (compressive force and tensile force) acting on the intermediate ring 14 continuous throughout one circumference of the tire, and the load acting on the bent portions of the first spokes 13 can be distributed throughout the entire tire. This has the effect of reducing the rolling resistance coefficient.

[0025] In the case where the second spoke 15 connects the intermediate ring 14 and the tread 12, the first minor angle formed by the adjacent first spoke of the first spoke 13 located to the right or left of the second spoke 15 in the circumferential direction and the intermediate ring 14 or the tread 12 connected to the adjacent first spoke, and the second minor angle formed by the second spoke 15 and the intermediate ring 14 or the tread 12 connected to the second spoke 15 may be acute angles. For example, in the airless tire 1 shown in FIG. 3, the second spoke 15 connects the outermost intermediate ring 14e and the tread 12, and the minor angle α1 formed by the adjacent first spoke 13a of the first spoke 13 located to the left of the second spoke 15 in the circumferential direction and the tread 12 connected to the adjacent first spoke 13a is the first minor angle. Also, the minor angle α2 formed by the second spoke 15 and the tread 12 connected to the second spoke 15 is the second minor angle. In the airless tire 1 shown in Fig. 3, the first minor angle α1 and the second minor angle α2 are both acute angles. Preferably, the second minor angle α2 is smaller than the first minor angle α1.

[0026] When at least one end of the second spoke 15 is connected to the intermediate ring 14, the distance in the circumferential direction between a first connection position between the second spoke 15 and the intermediate ring 14 and a second connection position, which is closer to the first connection position among the two connection positions between the intermediate ring 14 and the first spoke 13, may be 1 / 7 to 1 / 2 times the distance between the two connection positions. For example, in the airless tire 1 shown in FIG. 3, the second spoke 15 is connected to the intermediate ring 14e at the first connection position P2, and the intermediate ring 14e is connected to the first spokes 13a, 13b at two connection positions P1, P3, and the position P1, which is closer to the first connection position P2 among the two connection positions P1, P3, is the second connection position P1. In the airless tire 1 shown in FIG. 3, the circumferential distance D2 between the second connection position P1 and the first connection position P2 is 1 / 3 times the circumferential distance D1 between the connection positions P1, P3. In order to suppress excessive deformation (buckling) of the intermediate ring 14e, it is preferable that the circumferential distance D2 between the second connecting position P1 and the first connecting position P2 is approximately 1 / 3 to 1 / 4 times the distance D1 between the two connecting positions P1 and P3.

[0027] [Second embodiment] Fig. 4 is a front view showing another example of an airless tire according to an embodiment of the present invention, and Fig. 5 is an enlarged perspective view showing the airless tire of Fig. 4. As shown in Fig. 4, the airless tire 1a includes an inner ring 16 and an outer ring 17 in addition to a wheel 11, a tread 12, first spokes 13, an intermediate ring 14, and second spokes 15.

[0028] The inner ring 16 is an annular member that connects the inner ends of the first spokes 13, and is made of, for example, the same material as the first spokes 13 and the second spokes 15. The inner side of the inner ring 16 is joined to the wheel 11 on the outer side of the wheel 11. Specifically, the inner surface of the inner ring 16 may be provided with protrusions, and the protrusions of the inner ring 16 may be fitted into grooves formed in the rim 112 to join them, or the inner surface of the inner ring 16 and the outer surface of the rim 112 may be bonded to each other with an adhesive. The inner ends of the first spokes 13 and the second spokes 15 are joined to the inner ring 16 with, for example, an adhesive. The inner ring 16, the first spokes 13, and the second spokes 15 may be integrally molded.

[0029] The outer circumferential ring 17 is an annular member that connects the outer circumferential ends of the multiple first spokes 13, and is made of, for example, the same material as the first spokes 13 and the second spokes 15. The outer circumferential side of the outer circumferential ring 17 is joined to the tread 12 on the inner circumferential side of the tread 12. Specifically, the outer circumferential surface of the outer circumferential ring 17 is bonded to the inner circumferential surface of the tread 12 by an adhesive. The outer circumferential ends of the first spokes 13 and the second spokes 15 are joined to the outer circumferential ring 17 by, for example, an adhesive. Furthermore, the outer circumferential ring 17, the first spokes 13, and the second spokes 15 may be integrally molded, or the inner circumferential ring 16, the outer circumferential ring 17, the first spokes 13, and the second spokes 15 may be integrally molded.

[0030] By providing the inner ring 16, the bonding area with the rim 112 is increased compared to when the first spokes 13 are directly bonded to the wheel 11, improving the load-bearing capacity of the airless tire 1a. Similarly, by providing the outer ring 17, the bonding area with the tread 12 is increased compared to when the first spokes 13 are directly bonded to the tread 12, improving the load-bearing capacity of the airless tire 1a. The inner ring 16 and the outer ring 17 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.

[0031] In the case where the airless tire includes an inner ring 16, the first spokes 13 extend radially from the outer circumferential side of the inner ring 16 toward the inner circumferential side of the tread 12, connecting the inner ring 16 to the tread 12. In this case, the second spokes 15 connect at least one of (a) the first spokes 13 and the intermediate ring 14, (b) the first spokes 13 and the tread 12, (c) the intermediate ring 14 and the tread 12, (e) the inner ring 16 and the first spokes 13, and (f) the inner ring 16 and the intermediate ring 14.

[0032] Furthermore, in the case where the airless tire includes an outer circumferential ring 17, the first spokes 13 extend radially from the outer circumferential side of the rim 112 toward the inner circumferential side of the outer circumferential ring 17, connecting the wheel 11 to the outer circumferential ring 17. In this case, the second spokes 15 connect at least one of (a) the first spokes 13 and the intermediate ring 14, (b1) the first spokes 13 and the outer circumferential ring 17, and (c1) the intermediate ring 14 and the outer circumferential ring 17.

[0033] 4 and 5, when the airless tire includes an inner ring 16 and an outer ring 17, the first spokes 13 extend radially from the outer circumferential side of the inner ring 16 toward the inner circumferential side of the outer circumferential ring 17, connecting the inner ring 16 and the outer circumferential ring 17. In this case, the second spokes 15 connect at least one of (a) the first spoke 13 and the intermediate ring 14, (b1) the first spoke 13 and the outer circumferential ring 17, (c1) the intermediate ring 14 and the outer circumferential ring 17, (e) the inner ring 16 and the first spoke 13, and (f) the inner ring 16 and the intermediate ring 14.

[0034] The second spokes 15 in (f) suppress the deformation of the intermediate ring 14 itself, and the second spokes 15 in (e) suppress the deformation of the first spokes 13 that affects the deformation of the intermediate ring 14. In addition, the function of the second spokes 15 in (b1) and (c1) is similar to the function of the second spokes 15 in (b) and (c).

[0035] Fig. 6 is an enlarged front view showing part B in Fig. 4, in which five intermediate rings 14a, 14b, 14c, 14d, and 14e are provided between the inner ring 16 and the outer ring 17. The first spokes 13a and 13b shown in Fig. 6 have bent portions similar to the first spokes 13a and 13b shown in Fig. 3. The airless tire 1a shown in Fig. 6 differs from the airless tire 1 shown in Fig. 3 in that it has a plurality of second spokes 15a, 15b, and 15c aligned in the radial direction.

[0036] In the case where the airless tires 1, 1a include a plurality of intermediate rings 14 and the second spokes 15 connect the intermediate rings 14 to each other, as in the airless tire 1 shown in Fig. 3 and the airless tire 1a shown in Fig. 6, a first minor angle formed by an adjacent first spoke, among the first spokes 13, located to the right or left of the second spoke 15 in the circumferential direction, and the intermediate ring 14 connected to the adjacent first spoke, and a second minor angle formed by the second spoke 15 and the intermediate ring 14 connected by the second spoke 15 may be an acute angle. For example, in the airless tire 1a shown in Fig. 6, the second spoke 15a connects the intermediate rings 14c, 14d, and the minor angle β1 formed by the adjacent first spoke 13a, among the first spokes 13a, 13b, located to the left of the second spoke 15a in the circumferential direction, and the intermediate ring 14d connected to the adjacent first spoke 13a is the first minor angle. Also, the minor angle β2 formed by the second spoke 15a and the intermediate ring 14d connected to the second spoke 15a is the second minor angle. In the airless tire 1a shown in Fig. 6, the first minor angle β1 and the second minor angle β2 are both acute angles. Preferably, the second minor angle β2 is smaller than the first minor angle β1.

[0037] Furthermore, in the case where the airless tire 1a has a plurality of second spokes 15 arranged in the radial direction, the second spokes 15 may have a smaller second minor angle as they are closer to the tread 12. For example, in the airless tire 1a shown in FIG. 6, the second spoke 15a has the largest second minor angle β2, the second spoke 15b has the second largest second minor angle β3, and the second spoke 15c closest to the tread 12 has the smallest second minor angle β4. Furthermore, the second spokes 15a, 15b, 15c may have a larger thickness as they are closer to the tread 12. For example, in the airless tire 1a shown in FIG. 6, the second spoke 15a has the smallest thickness t1, the second spoke 15b has the second largest thickness t2, and the second spoke 15c closest to the tread 12 has the largest thickness t3. In this way, by further suppressing deformation of the radially outer intermediate rings 14, excessive deformation of some of the intermediate rings 14 can be suppressed, and the radial load can be supported by the entire airless tire 1a.

[0038] Fig. 7 is an enlarged front view showing a modified example of the second spoke 15 of the airless tire 1a shown in Fig. 6. In the example shown in (A), two second spokes 31, 32 are provided to connect the intermediate ring 14e and the outer peripheral ring 17. That is, two second spokes 31, 32 are present between two adjacent first spokes 13a, 13b. In the example shown in (B), a second spoke 33 is provided to connect the intermediate rings 14d, 14e, and in order to suppress deformation of the intermediate ring 14e, the thickness of the first spokes 13a, 13b on the outer side of the intermediate ring 14e is set to be larger than the thickness of the first spokes 13a, 13b on the inner side of the intermediate ring 14e, and the thickness of the intermediate ring 14e between the first spokes 13a, 13b is set to be larger than the thickness of the portion not between the first spokes 13a, 13b.

[0039] In the example shown in (C), a second spoke 34 is provided to connect the first spoke 13a to the intermediate ring 14e, and a second spoke 35 is provided to connect the first spoke 13b to the intermediate ring 14d. In the example shown in (D), a second spoke 36 is provided to connect the bent portions of the first spokes 13a, 13b to each other and to connect the intermediate ring 14e to the outer peripheral ring 17. In the example shown in (E), in addition to the second spoke 36 shown in (D), a second spoke 37 is provided that connects the bent portions of the first spokes 13a, 13b to each other and to connect the intermediate ring 14e to the outer peripheral ring 17, and that intersects with the second spoke 36.

[0040] [Action of the second spoke] The action of the second spoke 15 in the airless tire 1 will be described with reference to FIG. 8. FIG. 8 is an enlarged front view showing the second spoke 15 shown in FIG. 3. When a load (e.g., the vehicle weight) is applied to the airless tire 1 in a direction toward the bottom of the vehicle, a reaction force F1 corresponding to the vehicle weight is applied to the airless tire 1 from the road surface. The first spokes 13a, 13b are deformed by the reaction force F1 so as to be crushed in the vertical direction of the vehicle, and due to this deformation of the first spokes 13a, 13b, forces F2, F3 are applied to the intermediate ring 14e in a direction compressing the intermediate ring 14e. The intermediate ring 14e is deformed by the forces F2, F3, and, for example, the portion Z1 moves radially upward on the vehicle (i.e., in the direction of the arrow X), and the portion Z2 tries to move radially downward on the vehicle (i.e., in the direction of the arrow Y).

[0041] If the second spokes 15 were not provided, the portion Z1 would move in the direction of arrow X and the portion Z2 would move in the direction of arrow Y, causing the intermediate ring 14e to deform (buckle) into an S-shape. In contrast, the airless tire 1 shown in Fig. 8 is provided with the second spokes 15, which suppresses deformation of the portion Z1 and prevents the intermediate ring 14e from deforming (buckling) into an S-shape. This makes it possible to suppress impairment of the function of the intermediate ring 14e of transmitting the circumferential deformation of the first spokes 13 to the adjacent first spokes 13.

[0042] Furthermore, by providing the second spokes 15 in the airless tire 1, it is possible to suppress an increase in the rolling resistance coefficient (RRC) of the airless tire 1. The rolling resistance coefficient can be calculated using the following formula.

number

number

[0043] In the above formula 1 and formula 2, EN t indicates the energy loss in the tire, and L t is the effective circumference of the tire, and F z indicates the wheel load, and Si indicates the strain energy of each part, and tan δ i is the loss factor of the material, and V i indicates the volume of each part.

[0044] The structure of the airless tire 1 was modeled, a structural analysis was performed, and the strain energy S of each part of the tire was calculated. i Derive tan δ of the material. i The total energy loss of the tire, EN t can be derived, thereby allowing the rolling resistance coefficient to be calculated. When the rolling resistance coefficient was calculated by applying this method to the results of the structural analysis, the rolling resistance coefficient of the airless tire 1 according to the first embodiment shown in FIGS. 1 to 3 was reduced by about 10 to 30% compared to an airless tire not provided with second spokes 15. A similar effect of reducing the rolling resistance coefficient was also confirmed in the airless tire 1a according to the second embodiment shown in FIGS. 4 to 6.

[0045] In addition, the strain energy S in the above formula 2 i can also be considered as follows:

number

[0046] In the above formula 3, σ i indicates the stress in each part, and E i indicates the longitudinal elastic modulus of the material of each part.

[0047] In the above formula 3, the strain energy S i is the stress σ i Since the stress is proportional to the square of , a reduction in the stress contributes greatly to the strain energy, which also leads to a reduction in the rolling resistance coefficient in the above formulas 1 and 2. The second spokes 15 maintain the function of the intermediate ring 14e, and the circumferential deformation of the first spokes 13 is transmitted to the adjacent first spokes 13, thereby supporting the load with the entire airless tire 1, thereby suppressing the concentration of the load in the vicinity where the tread 12 contacts the ground. This reduces the stress (i.e., the peak value of the stress) in the vicinity of the contact point, which leads to a reduction in the rolling resistance coefficient.

[0048] [Embodiments of the present invention] According to this embodiment, an airless tire 1 is provided, which includes a plurality of elastic first spokes 13 radially arranged from an outer periphery of a wheel 11 coupled to a vehicle toward an inner periphery of a tread 12 that comes into contact with the road surface, an elastic intermediate ring 14 arranged between the wheel 11 and the tread 12 and connecting the plurality of first spokes 13 to each other, and elastic second spokes 15 connecting at least one of the first spokes 13 and the intermediate ring 14, the first spokes 13 and the tread 12, and the intermediate ring 14 and the tread 12. This makes it possible to suppress local deformation when a load is applied in the radial direction.

[0049] In the airless tire 1 of the present embodiment, the second spokes 15 include a plurality of the second spokes 15 arranged in the radial direction of the wheel 11. This makes it possible to further suppress local deformation when a load is applied in the radial direction.

[0050] In the airless tire 1 of the present embodiment, the second spokes 15 include the second spokes 15 provided between the intermediate ring 14, which is provided on the outermost side in the radial direction of the wheel 11, and the tread 12. This makes it possible to suppress loss of deformation balance between the inner and outer circumferential sides of the airless tire 1.

[0051] In the airless tire 1 of this embodiment, the second spokes 15 connect the intermediate ring 14 and the tread 12, and a first minor angle α1 formed between an adjacent first spoke among the first spokes 13 located to the right or left of the second spoke 15 in the circumferential direction of the wheel 11 and the intermediate ring 14 or the tread 12 connected to the adjacent first spoke, and a second minor angle α2 formed between the second spoke 15 and the intermediate ring 14 or the tread 12 connected to the second spoke 15 are acute angles. This makes it possible to suppress excessive deformation (buckling) of the intermediate ring 14.

[0052] The airless tire 1 of this embodiment includes a plurality of the intermediate rings 14, the second spokes 15 connect the intermediate rings 14 together, and a first minor angle β1 formed between an adjacent first spoke among the first spokes 13 located to the right or left of the second spoke 15 in the circumferential direction of the wheel 11 and the intermediate ring 14 connected to the adjacent first spoke, and a second minor angle β2 formed between the second spoke 15 and the intermediate ring 14 connected by the second spoke 15 are acute angles. This makes it possible to suppress excessive deformation (buckling) of the intermediate ring 14.

[0053] In the airless tire 1 of the present embodiment, the second minor angles α2, β2 are smaller than the first minor angles α1, β1, which makes it possible to further suppress excessive deformation (buckling) of the intermediate ring 14.

[0054] In the airless tire 1 of the present embodiment, the second spokes 15 include a plurality of the second spokes 15 arranged in the radial direction of the wheel 11, and the plurality of second spokes 15 have the second minor angle that decreases as they approach the tread 12. This makes it possible to suppress the deformation balance between the inner circumferential side and the outer circumferential side of the airless tire 1 from being lost.

[0055] In the airless tire 1 of this embodiment, at least one end of the second spoke 15 is connected to the intermediate ring 14, and a distance D1 in the circumferential direction of the wheel 11 between a first connection position P2 between the second spoke 15 and the intermediate ring 14 and a second connection position P1, of two connection positions P1, P3 between the intermediate ring 14 and the first spoke 13, which is closer to the first connection position P2, is 1 / 7 to 1 / 2 times the distance D2 between the two connection positions P1, P3. This makes it possible to further suppress excessive deformation (buckling) of the intermediate ring 14.

[0056] In the airless tire 1 of the present embodiment, the second spokes 15 include a plurality of the second spokes 15 arranged in the radial direction of the wheel 11, and the thickness of the plurality of second spokes 15 increases as they approach the tread 12. This makes it possible to suppress imbalance in deformation between the inner and outer circumferential sides of the airless tire 1.

[0057] In the airless tire 1 of this embodiment, the first spoke 13 has a plurality of bent portions 21, 22, 23, 24, and 25 between the end portion on the wheel 11 side and the end portion on the tread 12 side, and the thickness of the tread 12 is equal to or less than half the distance L between the bent portions 21, 22, 23, 24, and 25 in the radial direction of the wheel 11. This makes it possible to suppress the distortion energy of the tread 12 and to suppress an increase in rolling resistance.

[0058] The airless tire 1 of this embodiment includes an outer circumferential ring 17 that is joined to the tread 12 on the inner circumferential side of the tread 12 and is made of the same material as the second spokes 15, the first spokes 13 connect the wheel 11 and the outer circumferential ring 17, and the second spokes 15 connect at least one of the first spokes 13 and the intermediate ring 14, the first spokes 13 and the outer circumferential ring 17, and the intermediate ring 14 and the outer circumferential ring 17. This makes it possible to suppress breakage of the ends of the second spokes 15 on the outer circumferential side.

[0059] The airless tire 1 of this embodiment includes an inner ring 16 that is joined to the wheel 11 on the outer circumferential side of the wheel 11 and is made of the same material as the second spokes 15, the first spokes 13 connect the inner ring 16 and the outer circumferential ring 17, and the second spokes 15 connect at least one of the inner ring 16 and the first spokes 13, the inner ring 16 and the intermediate ring 14, the first spokes 13 and the intermediate ring 14, the first spokes 13 and the outer circumferential ring 17, and the intermediate ring 14 and the outer circumferential ring 17. This makes it possible to suppress breakage of the end portion on the inner circumferential side of the second spokes 15.

[0060] In the airless tire 1 of this embodiment, the first spoke 13 has a plurality of bent portions 21, 22, 23, 24, 25 between the end portion on the wheel 11 side and the end portion on the tread 12 side, the bent portions 21, 22, 23, 24, 25 are bent in a direction connecting the end portion on the wheel 11 side and the end portion on the tread 12 side, the intermediate ring 14 is connected to the bent portions 21, 22, 23, 24, 25, and the bent portions 21, 22, 23, 24, 25 connected to the same intermediate ring 14 are formed so as to be bent in the same direction with respect to the circumferential direction of the wheel 11. This allows a radial load to be transmitted in the circumferential direction by the intermediate ring 14, and the airless tire 1 as a whole can support the load. [Explanation of symbols]

[0061] 1,1a…Airless tires 11…Wheels 111...Disc 112…Rim 12…Tread 13,13a,13b…1st spoke 131, 132...End 14, 14a, 14b, 14c, 14d, 14e...Middle ring 15,15a,15b,15c…2nd spoke 16…Inner ring 17...Outer ring 21, 22, 23, 24, 25...Bends 31,32,33,34,35,36,37…2nd spoke D1,D2…distance F1…Reaction force F2,F3…force L…Distance P1,P2,P3…Position t1, t2, t3…Thickness α1,α2,β1,β2,β3,β4…Angle X,Y...Arrows

Claims

1. a plurality of elastic first spokes provided radially from an outer periphery of a wheel coupled to a vehicle toward an inner periphery of a tread that comes into contact with a road surface; an elastic intermediate ring provided between the wheel and the tread and connecting the first spokes to each other; An airless tire comprising: second spokes having elasticity, the second spokes connecting at least one of the first spokes and the intermediate ring, the first spokes and the tread, and the intermediate ring and the tread.

2. The airless tire according to claim 1 , wherein the second spokes include a plurality of the second spokes arranged in a radial direction of the wheel.

3. 3. The airless tire according to claim 1, wherein the second spokes include the second spokes provided between the intermediate ring provided on the outermost side in a radial direction of the wheel and the tread.

4. the second spoke connects the intermediate ring and the tread; 2. The airless tire according to claim 1, wherein a first minor angle formed between an adjacent first spoke among the first spokes located to the right or left of the second spoke in the circumferential direction of the wheel and the intermediate ring or the tread connected to the adjacent first spoke, and a second minor angle formed between the second spoke and the intermediate ring or the tread connected to the second spoke are acute angles.

5. A plurality of said intermediate rings, The second spokes connect the intermediate rings to each other, 2. The airless tire according to claim 1, wherein a first minor angle formed by an adjacent first spoke among the first spokes located to the right or left of the second spoke in the circumferential direction of the wheel and the intermediate ring connected to the adjacent first spoke, and a second minor angle formed by the second spoke and the intermediate ring connected by the second spoke are acute angles.

6. The airless tire according to claim 4 or 5, wherein the second minor angle is smaller than the first minor angle.

7. The second spokes include a plurality of the second spokes arranged in a radial direction of the wheel, The airless tire according to claim 4 or 5, wherein the second spokes have the second minor angle which decreases as they become closer to the tread.

8. The second spoke has at least one end connected to the intermediate ring, 3. The airless tire according to claim 1, wherein a distance in a circumferential direction of the wheel between a first connection position between the second spoke and the intermediate ring and a second connection position, of two connection positions between the intermediate ring and the first spoke, that is closer to the first connection position, is 1 / 7 to 1 / 2 times the distance between the two connection positions.

9. The second spokes include a plurality of the second spokes arranged in a radial direction of the wheel, The airless tire according to claim 1 , wherein the second spokes have a thickness that increases as they approach the tread.

10. the first spoke has a plurality of bent portions between the wheel side end and the tread side end, 3. The airless tire according to claim 1, wherein the tread thickness is equal to or less than half the distance between the bends in the radial direction of the wheel.

11. an outer circumferential ring joined to the tread on an inner circumferential side of the tread and made of the same material as the second spokes; the first spoke connects the wheel and the outer ring; The airless tire according to claim 1 or 2, wherein the second spokes connect at least one of the first spokes and the intermediate ring, the first spokes and the outer ring, and the intermediate ring and the outer ring.

12. an inner circumferential ring joined to the wheel on the outer circumferential side of the wheel and made of the same material as the second spokes; the first spoke connects the inner ring and the outer ring; 12. The airless tire of claim 11, wherein the second spoke connects at least one of the inner ring and the first spoke, the inner ring and the intermediate ring, the first spoke and the intermediate ring, the first spoke and the outer ring, and the intermediate ring and the outer ring.

13. the first spoke has a plurality of bent portions between the wheel side end and the tread side end, the bent portion is bent in a direction connecting the wheel side end portion and the tread side end portion, The intermediate ring is connected to the bent portion, The airless tire according to claim 1 or 2, wherein the bent portions connected to the same intermediate ring are formed so as to bend in the same direction relative to a circumferential direction of the wheel.

Images