Airless tires

Abstract

To provide an airless tire that can improve durability performance by suppressing damage from growing when a spoke is damaged as well.SOLUTION: An airless tire 1 comprises a tread ring 2, a hub 3 and a spoke 4. The spoke 4 includes a plurality of spoke boards 5. Each of the spoke boards 5 has a first end part 6 extending in a tire radial direction on one end side in a tire shaft direction, a second end part 7 extending in the tire radial direction on the other end side in the tire shaft direction, an inner end part 8 that is an end part on the hub 3 side, and an outer end part 9 that is an end part on the tread ring 2 side. The spoke board 5 includes a first spoke board 5A having a protruding part 10 protruding to outside in the tire shaft direction with respect to a virtual line VL1 linearly connecting a first inner end 8a on the one end side in the tire shaft direction of the inner end part 8 to a first outer end 9a on the one end side in the tire shaft direction of the outer end part 9.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an airless tire that can support a load by its own structure without using high-pressure air. [Background technology]

[0002] Conventionally, various airless tires in which a tread ring and a hub are connected by spokes are known. For example, the following Patent Document 1 proposes an airless tire in which the thickness of the spoke plate portion formed in an S-shape of the spoke is specified to suppress damage to the spoke plate portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-130071 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the airless tire of Patent Document 1, if the spoke plate portions come into contact with a bump or protrusion on the road surface and are damaged, the damage will grow as compressive and tensile forces act on the spoke plate portions as the tire is driven, causing vibrations and noise and ultimately leading to breakage.

[0005] The present invention has been devised in consideration of the above-mentioned circumstances, and its main object is to provide an airless tire that can suppress the growth of damage even if a spoke is damaged, thereby improving durability. [Means for solving the problem]

[0006] The present invention is an airless tire comprising a tread ring having a contact surface, a hub disposed radially inside the tread ring and fixed to an axle, and spokes for connecting the tread ring and the hub, wherein the spokes include a plurality of spoke plates, each of which has a first end portion extending in the tire radial direction at one end side in the tire axial direction, a second end portion extending in the tire radial direction at the other end side in the tire axial direction, an inner end portion which is an end portion on the hub side, and an outer end portion which is an end portion on the tread ring side, and the spoke plates include a first spoke plate having a protruding portion that protrudes outward in the tire axial direction further outward in the tire axial direction than an imaginary line connecting in a straight line a first inner end portion at one end side in the tire axial direction of the inner end portion and a first outer end portion at one end side in the tire axial direction of the outer end portion.

[0007] In the airless tire of the present invention, it is preferable that the protruding portion be formed in an arc shape by curving the first end portion of the first spoke plate outward in the tire axial direction.

[0008] In the airless tire of the present invention, it is preferable that the first end portion of the first spoke plate has arc-shaped recesses that curve inwardly in the tire axial direction on both sides of the protruding portion in the tire radial direction.

[0009] In the airless tire of the present invention, it is preferable that a radius of curvature of the protruding portion is larger than a radius of curvature of the recessed portion.

[0010] In the airless tire of the present invention, it is preferable that the second end portion of the first spoke plate has a straight portion extending linearly in a radial direction of the tire.

[0011] In the airless tire of the present invention, it is preferable that the spoke has a specified orientation for mounting to a vehicle, and that the first spoke plate is arranged so that the protrusion is positioned on the outer side of the vehicle when mounted to the vehicle.

[0012] In the airless tire of the present invention, it is desirable that the distance between the axially outermost end portions of a pair of circumferentially adjacent protrusions be smaller than a contact length in the circumferential direction of the tire when a normal load is applied to the tread ring.

[0013] In the airless tire of the present invention, it is preferable that the protruding portion protrudes axially outward beyond an axially outermost end portion of the tread ring and an axially outermost end portion of the hub.

[0014] In the airless tire of the present invention, it is preferable that the spoke plate further includes a second spoke plate not having the protrusion.

[0015] In the airless tire of the present invention, it is preferable that the spoke plate further includes a second spoke plate having a second protruding portion that protrudes outward in the tire axial direction beyond a second imaginary line that linearly connects a second inner end on the other end side of the inner end portion in the tire axial direction and a second outer end on the other end side of the outer end portion in the tire axial direction.

[0016] In the airless tire of the present invention, it is preferable that the first spoke plates and the second spoke plates are arranged alternately in the tire circumferential direction. Effect of the Invention

[0017] In the airless tire of the present invention, the spoke plate includes a first spoke plate having a protruding portion that protrudes axially outwardly from an imaginary line that linearly connects a first inner end at one end side of the inner end portion in the tire axial direction and a first outer end at one end side of the outer end portion in the tire axial direction.

[0018] Even if the spoke plate comes into contact with a step or a protrusion on the road surface and is damaged, the damage to the protrusions is prevented from growing to the entire spoke plate, and the spoke plate is prevented from being broken. Therefore, the airless tire of the present invention can improve durability by preventing the growth of damage even if the spoke is damaged. [Brief description of the drawings]

[0019] [Figure 1] 1 is a perspective view showing an embodiment of an airless tire of the present invention. FIG. [Diagram 2] FIG. 1 is a side view of an airless tire. [Diagram 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 1 is a side view of an airless tire in a ground contact state. [Diagram 5] FIG. 3 is a cross-sectional view taken along line BB in FIG. [Figure 6] FIG. 2 is an end view of the spoke plate as seen from the spoke width direction. [Figure 7] FIG. 11 is a cross-sectional view of a spoke of another embodiment as viewed in the tire circumferential direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a perspective view showing an airless tire 1 of this embodiment, and Fig. 2 is a side view of the airless tire 1. As shown in Fig. 1 and Fig. 2, the airless tire 1 of this embodiment includes a tread ring 2 having a ground contact surface 2a, a hub 3 disposed inside the tread ring 2 in the tire radial direction, and spokes 4 for connecting the tread ring 2 and the hub 3.

[0021] The hub 3 desirably includes a fixing portion 3a that is fixed to an axle (not shown) of a vehicle. Such an airless tire 1 can support the load acting on the tread ring 2 by the hub 3 and the spokes 4 without using high-pressure air. Therefore, the airless tire 1 of this embodiment is unlikely to get punctured.

[0022] The spokes 4 of this embodiment include a plurality of spoke plates 5 spaced apart in the tire circumferential direction. The spoke plates 5 are formed, for example, in a plate shape whose width in the tire axial direction is greater than its thickness in the tire circumferential direction. When a load acts on the tread ring 2, such spokes 4 can support the load by applying a tensile force to the spoke plates 5 located above the hub 3 and a compressive force to the spoke plates 5 located below the hub 3.

[0023] Fig. 3 is a cross-sectional view taken along line AA in Fig. 2. As shown in Fig. 3, each of the spoke plates 5 of this embodiment has a first end 6 extending in the tire radial direction from one end side in the tire axial direction, and a second end 7 extending in the tire radial direction from the other end side in the tire axial direction. The spoke plates 5 of this embodiment preferably further have an inner end 8 which is an end on the hub 3 side, and an outer end 9 which is an end on the tread ring 2 side.

[0024] The inner end portion 8 has, for example, a first inner end 8a at one end in the tire axial direction and a second inner end 8b at the other end in the tire axial direction. The outer end portion 9 has, for example, a first outer end 9a at one end in the tire axial direction and a second outer end 9b at the other end in the tire axial direction.

[0025] The spoke plate 5 of this embodiment includes a first spoke plate 5A having a protruding portion 10 that protrudes axially outward from an imaginary line VL1 that linearly connects the first inner end 8a and the first outer end 9a.

[0026] Even if the spoke plate 5 comes into contact with a step or a protrusion on the road surface and is damaged, the damage to the protrusion 10 prevents the damage from growing to the entire spoke plate 5, and prevents breakage of the spoke plate 5. Therefore, the airless tire 1 of this embodiment can improve durability by preventing the damage from growing even if the spoke 4 is damaged.

[0027] In a more preferred embodiment, the protrusion 10 is formed in an arc shape by curving the first end 6 of the first spoke plate 5A outward in the tire axial direction. Such a spoke plate 5 allows the protrusion 10 to be integrally formed, which helps reduce the manufacturing cost of the airless tire 1.

[0028] The protrusion 10 in this embodiment is formed in an arc shape having a single radius of curvature R1. It is preferable that the axially outermost end portion 10a of the protrusion 10 is provided at the center of the first spoke plate 5A in the tire radial direction. Such a protrusion 10 can protect a wide range in the tire radial direction. Note that the protrusion 10 is not limited to this embodiment, and for example, the outermost end portion 10a may be provided toward the outer side of the first spoke plate 5A in the tire radial direction.

[0029] The distance L1 between the outermost end portion 10a and the virtual line VL1 of the protrusion 10 is preferably 1 to 10 mm. By making the distance L1 1 mm or more, the protrusion 10 can be reliably in contact even if the spoke plate 5 comes into contact with a step or a protrusion on the road surface and is damaged. From this viewpoint, the distance L1 is more preferably 3 mm or more.

[0030] By setting the distance L1 to 10 mm or less, the protrusion 10 is prevented from becoming excessively large, which helps to reduce the weight of the airless tire 1 and also reduces air resistance, thereby improving the fuel efficiency performance of the airless tire 1.

[0031] It is preferable that the first end 6 of the first spoke plate 5A has arc-shaped recesses 11 that curve axially inward on both radial sides of the protrusion 10. Such a first spoke plate 5A can prevent damage from growing beyond the recesses 11 even if the protrusion 10 is damaged.

[0032] It is desirable that the radius of curvature R1 of the protrusion 10 is larger than the radius of curvature R2 of the recess 11. In such a first spoke plate 5A, the protrusion 10 can be formed large, and the protrusion 10 can come into contact with a step or a protrusion on the road surface when the first spoke plate 5A comes into contact with the step or a protrusion on the road surface.

[0033] It is desirable for the protrusion 10 to protrude axially outward beyond the axially outermost end portion 2b of the tread ring 2 and the axially outermost end portion 3b of the hub 3. Such a protrusion 10 can prevent the tread ring 2 and the hub 3 from contacting steps or protrusions on the road surface, and can further improve the durability of the airless tire 1.

[0034] The second end 7 of the first spoke plate 5A in this embodiment has a straight portion 12 extending linearly in the tire radial direction. Since such a first spoke plate 5A does not have a protruding portion 10 formed on the side of the second end 7, it is possible to reduce the weight of the airless tire 1 and improve the fuel efficiency performance of the airless tire 1.

[0035] The first spoke plate 5A of the present embodiment has a spoke width w1 measured along the surface 5a of the first spoke plate 5A from the first end 6 to the second end 7 at the same radial position of the tire. The spoke width w1 of the first spoke plate 5A is preferably smaller than the width W1 of the hub 3 and the width W2 of the tread ring 2. Such a first spoke plate 5A can further reduce the weight of the airless tire 1 and improve the fuel efficiency performance of the airless tire 1.

[0036] The spokes 4 of this embodiment have a specified orientation for attachment to a vehicle (not shown). The first spoke plate 5A is desirably arranged so that the protrusions 10 are located on the outer side of the vehicle when attached to the vehicle. Such spokes 4 can protect the outer side of the vehicle that is prone to contact with bumps and protrusions on the road surface without providing a large number of protrusions 10, and can achieve both low fuel consumption performance and durability performance for the airless tire 1.

[0037] The spoke plate 5 of the present embodiment further includes a second spoke plate 5B that does not have a protruding portion 10. That is, the first end portion 6 and the second end portion 7 of the second spoke plate 5B of the present embodiment have straight portions 12. By not forming the protruding portion 10, such a second spoke plate 5B helps to reduce the weight of the airless tire 1 and can improve the fuel efficiency performance of the airless tire 1.

[0038] The second spoke plate 5B of this embodiment has a spoke width w2 measured along the surface 5a of the second spoke plate 5B from the first end 6 to the second end 7 at the same radial position of the tire. The spoke width w2 of the second spoke plate 5B is preferably smaller than the width W1 of the hub 3 and the width W2 of the tread ring 2.

[0039] In this embodiment, the spoke width w2 of the second spoke plate 5B is smaller than the spoke width w1 of the first spoke plate 5A because the second spoke plate 5B does not have the protrusion 10. Such a second spoke plate 5B can further reduce the weight of the airless tire 1 and improve the fuel efficiency performance of the airless tire 1.

[0040] The spokes 4 are, for example, first spoke plates 5A and second spoke plates 5B arranged alternately in the tire circumferential direction. When such spokes 4 are mounted on a vehicle, the first spoke plates 5A and the second spoke plates 5B can be arranged in a balanced manner so that the protruding portions 10 are located on the outer side of the vehicle, and the airless tire 1 can achieve both good steering stability and good ride comfort.

[0041] Fig. 4 is a side view of the airless tire 1 in a ground contact state. As shown in Fig. 4, in the airless tire 1 of this embodiment, the distance L2 between the axially outermost end portions 10a of a pair of circumferentially adjacent protrusions 10 is smaller than the circumferential contact length L3 when a normal load is applied to the tread ring 2. Here, the "normal load" is a load determined for each tire by the manufacturer or the like.

[0042] Such an airless tire 1 can more reliably prevent damage to the spoke plates 5 in the contact area that is likely to come into contact with bumps or projections on the road surface. From this perspective, the distance L2 of the protrusion 10 is preferably 50% or less of the contact length L3.

[0043] Fig. 5 is a cross-sectional view of line BB in Fig. 2. As shown in Fig. 5, the inner end 8 of the spoke plate 5 of this embodiment extends at an incline with respect to the tire axial direction. Although not shown, it is preferable that the outer end 9 of the spoke plate 5 extends at an incline with the same angle as the inner end 8 in the same direction with respect to the tire axial direction.

[0044] The inclination angle of the inner end portion 8 and the outer end portion 9 with respect to the tire axial direction is preferably 2 to 10°. An inclination angle of 2° or more can improve the rigidity in the tire circumferential direction and improve the durability performance of the airless tire 1. An inclination angle of 10° or less can prevent the rigidity in the tire circumferential direction from becoming excessive and can improve the ride comfort performance of the airless tire 1.

[0045] It is desirable that the inner end 8 of the first spoke plate 5A and the inner end 8 of the second spoke plate 5B are inclined in opposite directions relative to the tire axial direction. Such spokes 4 have good balance in the tire axial direction, and can improve the ride comfort performance of the airless tire 1.

[0046] It is desirable that the angle θ1 of the inner end 8 of the first spoke plate 5A relative to the tire axial direction and the angle θ2 of the inner end 8 of the second spoke plate 5B relative to the tire axial direction are equal to each other. Such spokes 4 have good balance in the tire axial direction and can improve the ride comfort performance of the airless tire 1. Note that the angle θ1 of the inner end 8 of the first spoke plate 5A relative to the tire axial direction and the angle θ2 of the inner end 8 of the second spoke plate 5B relative to the tire axial direction may be different from each other, for example.

[0047] 6 is an end view of the spoke plate 5 as viewed in the direction of the spoke widths w1, w2. The end views of the spoke plate 5 of this embodiment are the same for the first spoke plate 5A and the second spoke plate 5B. As shown in FIG. 3 and FIG. 6, the spoke plate 5 of this embodiment has spoke widths w1, w2 and a spoke thickness t perpendicular to the surface 5a of the spoke plate 5.

[0048] Each of the spoke plates 5 of the present embodiment includes, when viewed from the direction of the spoke widths w1, w2, a first curved portion 13 curved so as to protrude in one direction in the tire circumferential direction on the hub 3 side, and a second curved portion 14 curved so as to protrude in the other direction in the tire circumferential direction on the tread ring 2 side. Such spoke plates 5 can improve the ride comfort performance of the airless tire 1 by the first curved portion 13 and the second curved portion 14.

[0049] In this embodiment, the amplitude a1 of the first curved portion 13 and the amplitude a2 of the second curved portion 14 are different from each other. In such a spoke plate 5, when a large compressive force acts on the spoke plate 5, such as when passing over a step, the direction of deformation can be limited to the side of the first curved portion 13 or the second curved portion 14 with the larger amplitude. This makes it possible to prevent the spoke plates 5 adjacent in the tire circumferential direction from contacting each other due to deformation, even when passing over a step.

[0050] The amplitude a2 of the second curved portion 14 is desirably larger than the amplitude a1 of the first curved portion 13. In this embodiment, the amplitude a2 of the second curved portion 14 is 1 to 3 mm larger than the amplitude a1 of the first curved portion 13. Such spoke plate 5 has a good vibration absorbing effect by increasing the deformation of the second curved portion 14 located on the outer side in the tire radial direction, and can improve the ride comfort performance of the airless tire 1.

[0051] The amplitude a1 of the first curved portion 13 in this embodiment is constant over the entire range of the spoke width w. Moreover, the amplitude a2 of the second curved portion 14 in this embodiment is constant over the entire range of the spoke width w. Such a spoke plate 5 can disperse distortion in the direction of the spoke width w when a compressive force is applied, and can further improve the durability of the airless tire 1.

[0052] It is desirable that the radius of curvature R3 of the first curved portion 13 and the radius of curvature R4 of the second curved portion 14 are equal to each other. Such a spoke plate 5 can limit the direction of change when a compressive force is applied to a direction based on the amplitude. In addition, this spoke plate 5 can distribute distortion when a compressive force is applied to the first curved portion 13 and the second curved portion 14, and can further improve the durability performance of the airless tire 1. Here, the radius of curvature R3 of the first curved portion 13 and the radius of curvature R4 of the second curved portion 14 are the radii of curvature of the center line 5c of the spoke thickness t.

[0053] In this embodiment, the center line 5c of the spoke thickness t at the inner end 8 extends parallel to the tire radial direction. In this embodiment, the center line 5c of the spoke thickness t at the outer end 9 also extends parallel to the tire radial direction, similar to the inner end 8. Such a spoke plate 5 can reduce distortion when a tensile force is applied, and can further improve the durability of the airless tire 1.

[0054] It is desirable that the center line 5c of the spoke thickness t of the inner end 8 and the center line 5c of the spoke thickness t of the outer end 9 are located on the same straight line when viewed from the direction of the spoke width w. Such a spoke plate 5 can limit the direction of change when a compressive force is applied to a direction based on the amplitude. In addition, such a spoke plate 5 can reduce distortion when a compressive force is applied, and can further improve the durability of the airless tire 1.

[0055] 1 and 2, the tread ring 2 is formed in a cylindrical shape from an elastic body such as rubber. The tread ring 2 desirably has a contact surface 2a formed thereon, which contacts the road surface during running, with a plurality of grooves 15. The contact surface 2a is not limited to this form, and may be, for example, block-shaped or may have a plurality of recesses formed thereon.

[0056] The hub 3 is formed of a non-elastic material such as metal. The hub 3 desirably has a disk-shaped fixing portion 3a that is fixed to the axle, and a cylindrical portion 3c that is connected to the spokes 4. The fixing portion 3a of the hub 3 has, for example, a plurality of fixing holes formed therein. The fixing portion 3a of the hub 3 is not limited to this embodiment, and may be, for example, one that can be attached to a dedicated axle with a single touch.

[0057] The spokes 4 are formed, for example, from a polymeric material having elasticity. The polymeric material is desirably selected from a single elastomer, two or more types of composite elastomers, or a fiber-reinforced elastomer. Such spokes 4 have an excellent balance of light weight, flexibility, and strength, and are useful for improving the fuel efficiency, ride comfort, and durability of the airless tire 1 in a well-balanced manner.

[0058] The spokes 4 of this embodiment include a plurality of spoke plates 5, an inner cylindrical portion 16 connected to the hub 3, and an outer cylindrical portion 17 connected to the tread ring 2. As a result, each of the spoke plates 5 is indirectly connected to the tread ring 2 and the hub 3.

[0059] Such spokes 4 can be firmly connected to the hub 3 and the tread ring 2, and can improve the durability performance of the airless tire 1. Note that the spokes 4 may, for example, omit the inner cylindrical portion 16 and the outer cylindrical portion 17, and each of the spoke plates 5 may be directly connected to the tread ring 2 and the hub 3.

[0060] 3, the straight portion 12 of the spoke plate 5 has, for example, an inner end 8 formed integrally with the inner cylindrical portion 16 via a curved portion 5b. Also, the spoke plate 5 has, for example, an outer end 9 formed integrally with the outer cylindrical portion 17 via a curved portion 5b.

[0061] When the inner cylindrical portion 16 and the outer cylindrical portion 17 are omitted, it is preferable that the inner end portion 8 and the outer end portion 9 of the spoke plate 5 are connected to the tread ring 2 and the hub 3 via the curved surface portion 5b, respectively. Such a curved surface portion 5b can reduce distortion occurring at the inner end portion 8 and the outer end portion 9, and can further improve the durability performance of the airless tire 1.

[0062] 7 is a cross-sectional view of a spoke 20 of another embodiment as seen from the tire circumferential direction. The same components as those of the above-mentioned embodiment are given the same reference numerals, and their description will be omitted. The spoke 20 of this embodiment includes a plurality of spoke plates 21, an inner cylindrical portion 22 connected to the hub 3, and an outer cylindrical portion 23 connected to the tread ring 2, similar to the above-mentioned spoke 4.

[0063] 7, the spoke plate 21 of this embodiment includes a first spoke plate 21A and a second spoke plate 21B. Similar to the above-mentioned first spoke plate 5A, the first spoke plate 21A has a first end 6 extending in the tire radial direction from one end side in the tire axial direction, and a second end 7 extending in the tire radial direction from the other end side in the tire axial direction. The spoke plate 21 of this embodiment preferably further has an inner end 8 which is the end on the hub 3 side, and an outer end 9 which is the end on the tread ring 2 side.

[0064] The first spoke plate 21A of this embodiment, like the first spoke plate 5A described above, has a protrusion 10 that protrudes outward in the tire axial direction beyond the imaginary line VL1 that linearly connects the first inner end 8a of the inner end portion 8 and the first outer end 9a of the outer end portion 9.

[0065] With such a first spoke plate 21A, even if the first spoke plate 21A comes into contact with a step or protrusion on the road surface and is damaged, the damage to the protrusion 10 prevents the damage from spreading to the entire first spoke plate 21A, and prevents the spoke plate 21 from being broken.

[0066] Similar to the above-described first spoke plate 5A, the first end 6 of the first spoke plate 21A preferably has arc-shaped recesses 11 that curve axially inward on both radial sides of the protrusion 10. Such a first spoke plate 21A can prevent damage from growing beyond the recesses 11 even if the protrusion 10 is damaged.

[0067] The second end 7 of the first spoke plate 21A in this embodiment has a straight portion 12 extending linearly in the tire radial direction, similar to the above-described first spoke plate 5A. Since such a first spoke plate 21A does not have a protruding portion 10 formed on the side of the second end 7, it is possible to reduce the weight of the airless tire 1 and improve the fuel efficiency performance of the airless tire 1.

[0068] The second spoke plate 21B in this embodiment has a second protruding portion 24 that protrudes outward in the tire axial direction from a second imaginary line VL2 that linearly connects a second inner end 8b at the other end side in the tire axial direction of the inner end portion 8 and a second outer end 9b at the other end side in the tire axial direction of the outer end portion 9.

[0069] With such a second spoke plate 21B, even if the second spoke plate 21B comes into contact with a step or protrusion on the road surface and is damaged, the damage to the second protrusion 24 prevents the damage from spreading to the entire second spoke plate 21B, thereby preventing breakage of the spoke plate 21.

[0070] The second protruding portion 24 is formed in an arc shape by curving the second end portion 7 of the second spoke plate 21B outward in the tire axial direction. Such a second spoke plate 21B allows the second protruding portion 24 to be integrally formed, which helps reduce the manufacturing cost of the airless tire 1.

[0071] The second protruding portion 24 of the present embodiment is formed in an arc shape having a single radius of curvature R5. The radius of curvature R5 of the second protruding portion 24 is preferably equal to the radius of curvature R1 of the protruding portion 10. Such a second protruding portion 24 can protect a wide range in the tire radial direction.

[0072] The second end 7 of the second spoke plate 21B desirably has arc-shaped second recesses 25 that curve axially inward on both radial sides of the second protruding portion 24. Such second spoke plate 21B can prevent damage from growing beyond the second recesses 25 even if the second protruding portion 24 is damaged.

[0073] The first end 6 of the second spoke plate 21B of this embodiment has a straight portion 12 extending linearly in the tire radial direction, similar to the above-described second spoke plate 5B. Since such a second spoke plate 21B does not have a second protruding portion 24 on the side of the first end 6, it is possible to reduce the weight of the airless tire 1 and improve the fuel efficiency performance of the airless tire 1.

[0074] The spokes 20 of this embodiment have first spoke plates 21A and second spoke plates 21B arranged alternately in the tire circumferential direction, similar to the above-described spokes 4. Such spokes 20 have good weight balance in the tire axial direction, and can improve the steering stability of the airless tire 1.

[0075] Although a particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment and can be modified in various ways. EXAMPLES

[0076] Airless tires having the basic structures shown in Figures 1 to 6 were prototyped based on the specifications in Table 1, and their durability and fuel economy performance were tested. The main common specifications and test methods are as follows:

[0077] <Common specifications> Tread ring width: 165mm Tread ring outer diameter: 502mm Tread ring inner diameter: 489mm Hub outer diameter: 304mm Number of spokes: 20 pairs Spoke inclination angle: 2°

[0078] <Durability> The prototype tire was mounted on a test vehicle and run on a road surface with the protrusions shown in Table 1, and the presence or absence of damage to the spoke plate was confirmed. The airless tire in which damage occurred was run using a drum testing machine under conditions of a load of 3.8 kN and a speed of 60 km / h, and after 24 hours, the length by which the damage to the spoke plate had grown inward in the tire axial direction from the imaginary line was measured. The results are expressed as an index, with the comparative example being set to 100 and the case where there was no growth inward in the tire axial direction from the imaginary line being set to 50, and the smaller the value, the smaller the growth of the damage and the more excellent the durability performance.

[0079] <Durability> The weight of the prototype tire was measured. The result is expressed as an index with the comparative example being 100, with a smaller value indicating a lighter weight and better fuel economy.

[0080] The test results are shown in Table 1. [Table 1]

[0081] As a result of the test, it was confirmed that the airless tires of the examples had less damage growth and improved durability performance compared to the comparative example. In addition, it was confirmed that the airless tires of the examples had a limited increase in weight compared to the comparative example, and had excellent overall performance evaluated as the sum of durability performance and fuel efficiency performance. [Explanation of symbols]

[0082] 1. Airless tires 2 Tread Ring 3. Hub 4 spokes 5 spoke plate 6 1st end 7 Second end 8 Inner end 8a 1st inner end 9 Outer end 9a 1st outer end 10 Protrusion

Claims

1. An airless tire, The tire comprises a tread ring having a ground contact surface, a hub disposed radially inward of the tread ring and fixed to an axle, and spokes for connecting the tread ring and the hub, The spokes include a plurality of spoke plates; Each of the spoke plates has a first end portion extending in a radial direction of the tire from one end side in the tire axial direction, a second end portion extending in the radial direction of the tire from the other end side in the tire axial direction, an inner end portion which is an end portion on the side of the hub, and an outer end portion which is an end portion on the side of the tread ring, the spoke plate includes a first spoke plate having a protruding portion protruding outward in the tire axial direction beyond an imaginary line linearly connecting a first inner end on one end side in the tire axial direction of the inner end portion and a first outer end on one end side in the tire axial direction of the outer end portion, The protruding portion is formed in an arc shape by curving the first end portion of the first spoke plate outward in the tire axial direction, The first end portion of the first spoke plate has an arc-shaped recess portion that curves inward in the tire axial direction on both sides of the protruding portion in the tire radial direction, The radius of curvature of the protrusion is greater than the radius of curvature of the recess. Airless tires.

2. An airless tire, The tire comprises a tread ring having a ground contact surface, a hub disposed radially inward of the tread ring and fixed to an axle, and spokes for connecting the tread ring and the hub, The spokes include a plurality of spoke plates; Each of the spoke plates has a first end portion extending in a radial direction of the tire from one end side in the tire axial direction, a second end portion extending in the radial direction of the tire from the other end side in the tire axial direction, an inner end portion which is an end portion on the side of the hub, and an outer end portion which is an end portion on the side of the tread ring, the spoke plate includes a first spoke plate having a protruding portion protruding outward in the tire axial direction beyond an imaginary line linearly connecting a first inner end on one end side in the tire axial direction of the inner end portion and a first outer end on one end side in the tire axial direction of the outer end portion, the protruding portion protrudes axially outward beyond an axially outermost end portion of the tread ring and an axially outermost end portion of the hub, Airless tires.

3. 3. The airless tire according to claim 1 or 2, wherein the spoke plate further includes a second spoke plate having a second protruding portion that protrudes outward in the tire axial direction beyond a second imaginary line that linearly connects a second inner end on the other end side in the tire axial direction of the inner end portion and a second outer end on the other end side in the tire axial direction of the outer end portion.

4. An airless tire, The tire comprises a tread ring having a ground contact surface, a hub disposed radially inward of the tread ring and fixed to an axle, and spokes for connecting the tread ring and the hub, The spokes include a plurality of spoke plates; Each of the spoke plates has a first end portion extending in a radial direction of the tire from one end side in the tire axial direction, a second end portion extending in the radial direction of the tire from the other end side in the tire axial direction, an inner end portion which is an end portion on the side of the hub, and an outer end portion which is an end portion on the side of the tread ring, The spoke plates include a first spoke plate having a protruding portion protruding outward in the tire axial direction beyond an imaginary line linearly connecting a first inner end of the inner end portion on one end side in the tire axial direction and a first outer end of the outer end portion on one end side in the tire axial direction, and a second spoke plate not having the protruding portion. Airless tires.

5. The airless tire according to claim 3 or 4, wherein the first spoke plates and the second spoke plates are arranged alternately in the tire circumferential direction.

6. The airless tire according to claim 1 , wherein the second end portion of the first spoke plate has a straight portion extending linearly in a radial direction of the tire.

7. The spokes have a specified orientation for attachment to the vehicle, The airless tire according to claim 1 , wherein the first spoke plate is disposed such that the protruding portion is positioned on an outer side of the vehicle when the airless tire is mounted on the vehicle.

8. 8. The airless tire according to claim 1, wherein a distance between axially outermost end portions of a pair of the protrusions adjacent to each other in the tire circumferential direction is smaller than a contact length in the tire circumferential direction when a normal load is applied to the tread ring.

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