Airless tires

Abstract

The body of the airless tire is manufactured using relatively small equipment. [Solution] The present invention relates to an airless tire comprising a wheel 10 for coupling to a vehicle, a plurality of spokes 22 which are elastic members and are periodically arranged in the circumferential direction on the outer circumference of the wheel, an intermediate ring 24 which is an elastic member and is arranged in the circumferential direction and connects adjacent spokes in the circumferential direction, and a body portion 20 which consists of spokes and an intermediate ring, and a tread ring 30 which is an elastic support member and is arranged on the outermost circumference of the spokes, wherein the body portion is formed from divided body portions 21 which are divided in the circumferential direction, and a connecting portion 27 which connects the divided body portions to each other is provided near the intersection of the spokes and the intermediate ring.

Description

Technical Field

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[0001] The present invention relates to a non-pneumatic tire.

Background Art

[0002] As an example of a non-pneumatic tire that does not use air, the tire described in Patent Document 1 is known. This prior art tire includes an annular outer surface, an annular inner surface, and a plurality of spokes extending between the outer surface and the inner surface in a plurality of spoke rings including a first spoke ring adjacent to a second spoke ring. The first spoke ring has a first rigidity, the second spoke ring has a second rigidity different from the first rigidity, and includes a tread layer extending circumferentially around the annular outer surface of the plurality of spoke rings.

Prior Art Documents

Patent Documents

[0007] According to the above-mentioned airless tire, the body of the airless tire can be manufactured using relatively small equipment. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing an airless tire according to an embodiment. [Figure 2] This is a schematic diagram showing the segmented body sections that make up an airless tire. [Figure 3] Figure 2 is a schematic diagram showing the divided body section. [Figure 4] This is a schematic enlarged view showing the divided body section. [Figure 5] This is a schematic diagram showing the forces acting on the segmented body. [Figure 6] This is a schematic diagram showing the forces acting on the segmented body. [Figure 7] This is a schematic diagram showing a divided body portion according to the second embodiment. [Figure 8] This is a schematic diagram showing the connection between the wheel and the body. [Figure 9] This is a schematic diagram showing a segmented body portion according to a modified example of the second embodiment. [Figure 10] This is a schematic diagram showing a segmented body portion according to a modified example of the second embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the attached drawings. In the drawings, the same reference numerals are used for identical components, and redundant descriptions are omitted. In the drawings, the size and proportions of each component are exaggerated to facilitate understanding of the embodiments and may differ from the actual size and proportions.

[0010] (First Embodiment) Figure 1 is a schematic diagram showing an airless tire according to an embodiment. Figure 2 is a schematic diagram showing the segmented body portion 21 that constitutes the airless tire. Figure 3 is a schematic diagram showing the segmented body portion 21 according to Figure 2. Figure 4 is an exploded enlarged view showing the segmented body portion 21. Figures 5 and 6 are schematic diagrams showing the forces acting on the segmented body portion 21.

[0011] The airless tire according to this embodiment can be used for passenger car tires. As shown in Figure 1 and other figures, the airless tire according to this embodiment has a wheel 10, a body portion 20, and a tread ring 30. The body portion 20 can be integrated with the wheel 10 by press-fitting it into the wheel 10. The tread ring 30 can also be integrated with the body portion 20 by press-fitting it into the body portion 20. Each component will be described in detail below.

[0012] (wheel) The wheel 10 is fixed to the hub of a vehicle (not shown) (see part P in Figure 1 for the connection point with the vehicle). The wheel 10 is composed of, for example, a disc-shaped disc and a cylindrical rim, and is made of metal or other highly rigid material. In the front view of Figure 1, the wheel disc is shown as a circular member in the center of the airless tire, and this disc is fixed to the hub of the vehicle, thereby supporting the airless tire on the axle. The airless tire is positioned on the outer circumference of the wheel 10. The outer circumference of the wheel 10 is made of a curved surface, and is joined to the body portion 20 of the airless tire by adhesive or the like. However, the airless tire may be joined or connected to the wheel 10 by providing grooves on the outer surface of the wheel 10 or by providing a bolt fixing mechanism.

[0013] (Body part) The body portion 20 is the area between the wheel 10 and the tread ring 30, and includes a divided body portion 21 that is divided in the circumferential direction. For convenience, the divided body portion 21 is not shown in Figure 1. As shown in Figure 2, the divided body portion 21 includes spokes 22, spoke inner rings 23, intermediate rings 24, and spoke outer rings 25. The divided body portion 21 is made of an elastically deformable material and holds the wheel load, mitigates the impact on the vehicle due to road surface irregularities, and generates a lateral load on the tire as the tire deforms due to the tire's side slip angle. In this embodiment, the divided body portion 21 is configured with a central angle of approximately 45 degrees.

[0014] The spokes 22 are arranged radially outward and periodically in the circumferential direction on the outer circumference of the wheel 10. The spokes 22 are made of an elastic material such as an elastic thermoplastic resin such as urethane or an elastic thermosetting resin, and are plate-shaped members having a width corresponding to the tire width. In this embodiment, the spokes 22 extend substantially radially (in a direction intersecting the circumferential direction) from the outer circumference of the wheel 10 toward the inner circumference of the tread ring 30, although the center of the circle does not pass through it, and are configured to be provided in multiples at equal intervals, spaced apart from each other along the circumferential direction of the tire. The multiple spokes 22 are provided axially symmetric with respect to the central axis of the tire. The number of spokes 22 provided on one airless tire is not particularly limited and can be set appropriately according to the tire's contact length, the load capacity of the spokes 22, vibration resistance, and other tire requirements. The load supported by the body portion 20 is mainly due to the deformation of the spokes 22, and the intermediate ring 24 suppresses the deformation of circumferentially adjacent spokes 22, distributing the load throughout the entire tire.

[0015] As shown in FIG. 3, one spoke 22 forms a bent portion 26 that bends in a direction connecting the wheel-side end and the tread-side end between these two ends (see FIG. 2). The bent portion 26 is formed at the end of the spoke 22 of the divided body portion 21 adjacent in the circumferential direction. As shown in FIG. 2, the spoke 22 is formed in a zigzag shape when viewed in the tire rotation axis direction. In the present embodiment, as shown in FIG. 2, five bent portions 26 are formed from the wheel-side end toward the tread-side end. Due to the wheel load, a pressing force acts on the bent portion 26 in the vertical direction (see the arrow in FIG. 4).

[0016] The spoke inner peripheral ring 23 is provided adjacent to the wheel 10 on the radially outer side of the wheel 10. The spoke outer peripheral ring 25 is provided adjacent to the tread ring 30 on the radially inner side of the tread ring 30. The spoke 22, the intermediate ring 24, the spoke inner peripheral ring 23, and the spoke outer peripheral ring 25 can be formed by bonding the same material or different materials. In particular, if they are of the same material, their interfaces can be made stronger than in the case of different materials. In that case, by using a material such as urethane resin (TPU), elastic deformation is possible, and a material with a low tanδ characteristic of the material can be used, realizing vibration reduction and rolling resistance reduction by the tire.

[0017] The intermediate ring 24 is arranged in the circumferential direction and is configured to connect the spokes 22 that are circumferentially adjacent between the wheel 10 and the tread ring 30. The intermediate ring 24 is made of an elastic material such as a thermoplastic resin having elasticity or a thermosetting resin having elasticity, similar to the spokes 22, and is provided to connect with a plurality of spokes 22 between the wheel 10 and the tread ring 30. The intermediate ring 24 has a cylindrical shape with a tire width concentric with the wheel 10 and the tread ring 30. The number of intermediate rings 24 provided in one airless tire is not particularly limited, but by setting the number of intermediate rings 24 to an even number such as 2 or 4, the balance of the forces in the circumferential direction of the tire is maintained. Therefore, the axial forces (compressive force and tensile force) acting on the intermediate ring 24 throughout one circumference of the tire become continuous, and the load acting on the bent portion 26 of the spoke 22 can be dispersed over the entire tire. As a result, there is an effect of reducing the rolling coefficient. The spoke 22 and the intermediate ring 24 intersect at the bent portion 26.

[0018] If the degree of bending of the bent portion 26 is extremely small, the spoke 22 will undergo buckling deformation between the bent portions 26 and will not deform at the bent portion 26, so the amount of deformation in the circumferential direction of the tire cannot be regulated. Therefore, although the inferior angle of the bent portion 26 shown in FIG. 3 is not particularly limited, it is desirable to set it to less than 120°. A connecting portion 27 of the adjacent divided body portions 21 is provided at the bent portion 26 where the spoke 22 and the intermediate ring 24 intersect. The connecting portion 27 connects the adjacent divided body portions 21 that are divided in the circumferential direction. In this embodiment, as an example, the adjacent divided body portions 21 are connected using an adhesive such as a urethane-based adhesive, but they may also be connected using only the connecting portion 27 without using an adhesive.

[0019] The body portion 20, consisting of the spokes 22, spoke inner rings 23, intermediate rings 24, and spoke outer rings 25 described above, is divided in the circumferential direction to form divided body portions 21. The connecting portions 27 that connect the divided body portions 21 are configured to be provided near the intersection of the spokes 22 and the intermediate rings 24. In this way, it is possible to construct a cylindrical body portion 20 from the circumferentially divided body portions 21, and the mold used to mold the body portion 20 for the entire circumference of the tire can be made using a mold with a limited area. This reduces the manufacturing cost of the mold and thus the cost of the airless tire. In addition, by providing the connecting portions 27 near the intersection of the intermediate rings 24 and spokes 22, buckling of the intermediate rings 24 can be prevented or suppressed. Note that since the divided body portions 21 are divided in the circumferential direction, a circumferential force acts on the connecting portions 27 when the divided body portions 21 are connected by the connecting portions 27 (see arrow in Figure 6).

[0020] Furthermore, bent portions 26 are formed at the ends of the spokes 22 of adjacent segmented body portions 21 in the circumferential direction. The bent portions 26 of adjacent spokes 22 in the circumferential direction are bent in the same direction relative to the circumferential direction, and the intermediate ring 24 is configured to connect with the vicinity of the spokes 22. This structure, in which the spokes are bent in the same direction relative to the circumferential direction, allows the intermediate ring 24 to transmit the radial deformation of the tire caused by the wheel load to the entire tire, thereby suppressing localized tire loads.

[0021] Furthermore, the connecting portion 27 formed on the bent portion 26 is configured to be formed on the side with the smaller angle between the bent portion 26 and the spokes. This configuration allows a compressive force to act on the spokes 22 in the radial direction of the tire, creating an effect that encloses the connecting portion 27 provided on the intermediate ring 24, making it difficult for the intermediate ring 24 to detach from the connecting portion 27. In addition, the force that suppresses the convex shape increases the bonding force of the connecting portion 27, allowing the wheel load to be distributed across the entire tire.

[0022] Furthermore, the length L between spokes of the intermediate ring 24 is configured such that the portion without the connecting portion 27 is shorter than the portion with the connecting portion 27 (L') (see Figure 5). This configuration allows a compressive force to act on the intermediate ring 24 when the divided body portions 21 are connected via the connecting portion 27. This makes it less likely for the connected intermediate ring 24 to come off the spokes 22.

[0023] Furthermore, a spoke inner ring 23 is provided on the inner circumference side of the spoke 22, and a spoke outer ring 25 is provided on the outer circumference side, with a connecting portion 27 between the spoke inner ring 23 and the spoke outer ring 25. This configuration strengthens the connection of the divided body parts 21 so that the entire body part 20 does not fall apart.

[0024] (Treadring) The tread ring 30 is formed in a cylindrical shape with the width of the tire and is located on the outermost circumference of the airless tire. The tread ring 30 can be made of a composite material in which an elastic material such as natural rubber or synthetic rubber is reinforced with metal or resin tire cords. A tread pattern is formed on the outer surface of the tread ring 30, similar to that of a conventional pneumatic tire, and it becomes the contact surface with the road surface.

[0025] When mounted on a vehicle, the wheel load held by the tire is supported by the elastic deformation of the body section 20 and the tread ring 30. The load supported by the body section 20 is mainly due to the deformation of the spokes 22, while the intermediate ring 24 suppresses the deformation of adjacent spokes 22 in the circumferential direction, distributing the load across the entire tire. In order to hold the wheel load in an airless tire, the circumferential rigidity (not deforming even when a load is applied in the circumferential direction) of the tread ring 30 should not be excessively high, nor should the radial rigidity (not deforming even when a load is applied in the radial direction) be excessively high in order to mitigate road surface irregularities and ensure contact with the ground.

[0026] When the tread ring 30 is constructed from a single material, increasing the circumferential rigidity requires using a harder material or increasing its thickness, which also increases the radial rigidity. To avoid this, it is preferable to adopt a composite structure in which reinforcing fibers such as metal or capillaries are embedded in the rubber or resin tread ring 30.

[0027] (Second Embodiment) Figure 7 is a schematic diagram showing the segmented body portion 21a that constitutes the body portion of the airless tire according to the second embodiment. Figure 8 is a schematic diagram showing the connection between the wheel 10a and the segmented body portion 21a that constitutes the body portion. In the first embodiment, it was explained that the spoke inner circumferential ring 23 is adjacent to the wheel 10 in the radial direction, but it can be configured as follows.

[0028] The spoke inner circumference ring 23a is configured to be adjacent to the outermost circumference of the wheel 10 in the axial direction. In the first embodiment, the wheel 10 and the body portion 20 are integrated by press-fitting the body portion 20 onto the wheel 10. However, in the second embodiment, the wheel 10a and the body portion 20 can be integrated by inserting a bolt bt or the like through the hole 28 of the spoke inner circumference ring 23a and tightening the bolt bt and nut nt (see Figures 7 and 8).

[0029] Figures 9 and 10 are schematic diagrams showing divided body sections 21b and 21c according to a modified example of the second embodiment. In Figure 7, the body section is divided into divided body sections 21a at approximately 45-degree intervals with a central angle. However, the division of the body section 20 is not limited to Figure 7. In addition to the above, as shown in the divided body sections 21b and 21c of Figures 9 and 10, the division of the body section 20 may be configured at any angle as appropriate, for example, with a central angle of approximately 30 degrees.

[0030] Furthermore, in the first embodiment, the connecting portion 27 connects the divided body portion 21 by fitting a concave shape and a convex shape together, and the same configuration is shown in Figures 7 and 9. However, the shape of the connecting portion 27c is not limited to this, and as shown in Figure 10, one side may have a shape in which the inner circumference partially protrudes in the circumferential direction from the circumference of the divided body portion 21c, while the outer circumference portion that abuts the inner circumference portion of the other side may partially protrude in the circumferential direction.

[0031] Furthermore, in the first embodiment, the connecting portion 27 is provided on the bent portion 26, and is similarly configured in Figure 9. However, as shown in Figures 7 and 10, the connecting portions 27a and 27c may be provided at locations other than the bent portion 26.

[0032] Furthermore, in Figures 7, 9, and 10, the wheel 10, spokes 22, intermediate ring 24, spoke outer ring 25, bent portion 26, and tread ring 30 are the same as in the first embodiment, so their description is omitted.

[0033] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. In the above description, the outer circumference of the wheel 10 is connected to the body portion 20 via the spoke inner circumference ring 23, but the spokes may be directly connected to the wheel 10. Also, the tread ring 30 is connected to the body portion 20 via the spoke outer circumference ring 25, but the spokes may be directly connected to the tread ring 30.

[0034] Furthermore, the following embodiments are also included in the scope of the present invention: an airless tire according to claim 1 having the features of claim 2; an airless tire according to claim 2 having the features of claim 3; an airless tire according to any one of claims 1 to 3 having the features of claim 4; an airless tire according to any one of claims 1 to 4 having the features of claim 5; an airless tire according to any one of claims 1 to 4 having the features of claim 6. [Explanation of Symbols]

[0035] 10 wheels, 20 Body section, 21, 21a, 21b, 21c Divided body section, 22 spokes, 23 spoke inner circumference ring, 24 intermediate rings, 25 spoke outer ring, 26. Bending section, 27 Connecting part, 30 tread rings, L, L' length.

Claims

1. Wheels for connecting to the vehicle, Multiple spokes, which are elastic members, are periodically arranged in the circumferential direction on the outer circumference of the wheel. It has an intermediate ring which is an elastic member, which is arranged in the circumferential direction and connects adjacent spokes in the circumferential direction, and a body portion which consists of the spokes and the intermediate ring, In an airless tire comprising a tread ring, which is an elastic support member, positioned on the outermost circumference of the spokes, The airless tire is formed from circumferentially divided body sections, and connecting sections for connecting the divided body sections are provided near the intersection of the spokes and the intermediate ring.

2. In the circumferential direction, in adjacent divided body portions, the spokes have bent portions formed. The bent portions of the spokes adjacent to each other in the circumferential direction are bent in the same direction with respect to the circumferential direction. The airless tire according to claim 1, wherein the intermediate ring is connected to the vicinity of the spokes.

3. The airless tire according to claim 2, wherein the connecting portion is configured on the side with the smaller angle between the bent portions.

4. The airless tire according to any one of claims 1 to 3, wherein the length L between the spokes of the intermediate ring is shorter in the portion without the connecting portion than in the portion with the connecting portion.

5. The airless tire according to claim 1, wherein a spoke inner ring is provided on the inner circumference side of the spoke, and the spoke inner ring also has the connecting portion.

6. The airless tire according to claim 1, wherein a spoke outer ring is provided on the outer circumference of the spoke, and the spoke outer ring also has the connecting portion.

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