Airless tire and its manufacturing method

Abstract

To provide an airless tire with spokes having high buckling strength, and to provide a manufacturing method of the airless tire.SOLUTION: An airless tire includes: an elastic outer peripheral ring 14 disposed at the inner periphery side of a tread 15 which contacts with a ground surface; multiple elastic spokes 12 which are provided in a radial form from the outer periphery side of a wheel 11 coupled to a vehicle toward the outer peripheral ring 14; and first ribs 21 provided at the spokes 12 and extending in a radial direction of a tire along an extension direction of the spokes 12.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a non-pneumatic tire (also referred to as a non-air pressure tire) and a method for manufacturing the same.

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 a band portion including an inner band and an outer band that is spaced apart from the inner band and is provided so as to surround the outer peripheral surface of the inner band, and a plurality of first spokes provided between the inner band and the outer band and repeatedly provided in the circumferential direction so as to connect the inner band and the outer band. In this prior art, since the first spoke has a shape in which "W" is rotated 90 degrees with respect to the tire radial direction when viewed from the tire side surface, it is said that the load support ability and the shock buffering function are excellent, and the braking and traction performance are improved.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the W-shaped spoke adopted in the above prior art has a problem that when the wheel load increases, the central portion of the spoke greatly bends, easily accompanied by a buckling phenomenon, and cannot hold a large wheel load.

[0005] The problem to be solved by the present invention is to provide a non-pneumatic tire with high buckling strength of the spoke and a method for manufacturing the same.

Means for Solving the Problems

[0006] The present invention relates to an airless tire having a plurality of spokes arranged radially from the outer circumference of a wheel attached to a vehicle toward an outer ring, wherein the spokes are provided with a first rib that extends radially along the direction in which the spoke extends. The first rib is provided on the spoke such that the second moment of area of ​​the first rib in the radial direction of the tire is greater than the second moment of area of ​​the spokes excluding the first rib. This solves the above problems. [Effects of the Invention]

[0007] According to the present invention, by providing a first rib on the spoke, the buckling strength of the spoke can be increased. This makes it possible to hold a large wheel load. [Brief explanation of the drawing]

[0008] [Figure 1] This is a front view showing the basic structure of an airless tire according to an embodiment of the present invention. [Figure 2A] Figure 1 is a perspective view showing the rim of the wheel. [Figure 2B] Figure 2A is an exploded perspective view showing the rim of the wheel in disassembled form. [Figure 2C] This is a perspective view showing another example of a wheel according to an embodiment of the present invention. [Figure 3] This is a perspective view showing an airless tire 1 according to a first embodiment of the present invention. [Figure 4] Figure 3 shows an enlarged perspective view and an enlarged front view of section IV. [Figure 5] This is a cross-sectional view along the VV line in Figure 4(B). [Figure 6] This is a cross-sectional view corresponding to the cross-sectional view along the VV line in Figure 4(B), showing another example of the embodiment shown in Figure 5. [Figure 7A] This is an enlarged perspective view showing a portion of the airless tire according to the second embodiment of the present invention, corresponding to part IV in Figure 3. [Figure 7B] This is a front view of a portion of the spokes of an airless tire according to a second embodiment of the present invention. [Figure 8]Perspective view (A) and front view (B) showing an enlarged part corresponding to part VIII in FIG. 1 of the airless tire according to the third embodiment of the present invention. [Figure 9] Cross-sectional view taken along line IX-IX of FIG. 8(B). [Figure 10] Cross-sectional view corresponding to the cross-sectional view taken along line IX-IX of FIG. 8(B), showing another example of the embodiment shown in FIG. 9. [Figure 11A] Enlarged front view showing an enlarged part corresponding to part IIIV in FIG. 1 of the airless tire according to the first embodiment of the present invention. [Figure 11B] Enlarged front view corresponding to part IIIV in FIG. 1, showing another example of the first embodiment in FIG. 3A. [Figure 11C] Perspective view showing an enlarged part corresponding to part VIII in FIG. 1 of the airless tire according to the third embodiment of the present invention. [Figure 12] Front view and cross-sectional view of a mold including a tire showing an embodiment of the manufacturing method of the airless tire according to the present invention. [Figure 13] Perspective view of a tire showing another embodiment of the manufacturing method of the airless tire according to the present invention. [Figure 14] Plan view of a tire showing still another embodiment of the manufacturing method of the airless tire according to the present invention.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The airless tires according to the embodiments of the present invention described below can be applied not only to four-wheel automobiles, two-wheel automobiles, industrial vehicles, bicycles, and other vehicles, but also to wheels of carts and the like.

[0010] 《Basic Structure of Airless Tire》 FIG. 1 is a front view showing the basic structure of the airless tire 1 according to an embodiment of the present invention. The X-axis in the XYZ space shown in the figure corresponds to the front-rear direction of the vehicle when the tire is mounted on the vehicle, the Y-axis corresponds to the width direction of the vehicle, and the Z-axis corresponds to the vertical direction of the vehicle. Referring to this FIG. 1, the configuration common to the first embodiment, the second embodiment, and the third embodiment described later will be first explained. As shown in FIG. 1, the airless tire 1 of the present embodiment includes a wheel 11, a spoke 12, an intermediate ring 13, an outer peripheral ring 14, and a tread 15. However, since the intermediate ring 13 is not an essential component of the airless tire according to the present invention, it can be omitted as necessary.

[0011] The wheel 11 is fixed to a hub of a vehicle not shown. The wheel 11 is composed of, for example, a disk 111 having a disk shape and a rim 112 having a cylindrical shape, and is made of metal or other high-rigidity materials. The disk 111 of the wheel 11 is shown as a circular member at the center of the airless tire 1 in the front view of FIG. 1, and this disk 111 is fixed to the hub of the vehicle, whereby the airless tire 1 is supported by the axle.

[0012] Figure 2A is a perspective view showing the rim 112 of the wheel 11 in Figure 1, and Figure 2B is an exploded perspective view of the rim 112. In Figures 2A and 2B, for ease of understanding, the disc 111 of the wheel 11 connected to the vehicle hub is omitted from the illustration, and only the rim 112 of the wheel 11 into which the spokes 12 are fitted is shown. In this embodiment, the rim 112 of the wheel 11 is structured to be divided into two members 112a and 112b in the width direction of the tire. Multiple grooves 113 are formed on the outer circumferential surface of the rim 112, and the inner circumferential ends of the spokes 12 are fitted into these grooves 113. The grooves 113 are provided substantially evenly along the circumferential direction of the outer circumferential surface of the rim 112, and their cross-section is anchor-shaped. When attaching the spokes 12 to the rim 112, as shown in Figure 2B, the rim 112 is disassembled into two parts 112a and 112b. The inner circumferential end of the spoke 12, which has a cross-sectional shape that matches the anchor shape, is inserted into the groove 113. The inner circumferential end of the spoke 12 is then sandwiched between the two parts 112a and 112b, and the two parts 112a and 112b are joined together with fastening members such as bolts. As a result, multiple spokes 12 are constrained to the wheel 11 in both the radial and circumferential directions.

[0013] The means of attaching the spokes 12 to the wheel 11 are not limited to this example, as long as robustness can be ensured. For example, the outer surface of the rim 112 of the wheel 11 and the inner end of the spoke 12 may be bonded together using an adhesive. Alternatively, the outer surface of the rim 112 of the wheel 11 and the inner end of the spoke 12 may be directly joined together using bolts, without providing a groove 113 on the outer surface of the rim 112 of the wheel 11. Furthermore, an annular inner ring may be provided to connect the inner ends of multiple spokes 12, and this inner ring may be bonded to the outer surface of the rim 112 of the wheel 11 using an adhesive. In this case, a projection that engages with a groove 113 formed in the rim 112 of the wheel 11 may be provided on the inner surface of the inner ring, creating a structure that engages the inner ring and the wheel 11.

[0014] The rim 112 of the wheel 11 shown in Figures 2A and 2C is structured to be divided into two members 112a and 112b in the width direction of the tire, but the wheel 11 of this embodiment is not limited to this. Figure 2C is a perspective view showing another example of a wheel according to an embodiment of the present invention. The wheel 11 of this embodiment may be a single rim 112 that is not divided as shown in Figure 2C.

[0015] Returning to Figure 1, the tread 15 is formed in a cylindrical shape with the width of the tire and is located on the outermost circumference of the airless tire 1. The tread 15 is 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 15, similar to that of a conventional pneumatic tire, and it forms the contact surface with the road surface.

[0016] The outer ring 14 is a cylindrical member having a width equivalent to the tire width, connecting the tread-side ends of the multiple spokes 12, and is fastened to the inner circumferential surface of the tread 15 by means of adhesive or other means. The outer ring 14 is made of an elastic material such as an elastic thermoplastic resin or an elastic thermosetting resin, and may be integrally molded with the spokes 12.

[0017] The above describes the basic structure of the airless tire 1 according to an embodiment of the present invention. Below, embodiments of the configuration of the spokes 12 and intermediate ring 13 provided between the wheel 11 and the tread 15 will be described.

[0018] 《First Embodiment》 Figure 3 is a perspective view showing an airless tire 1 according to the first embodiment of the present invention, Figure 4(A) is an enlarged perspective view showing part IV of Figure 3, and Figure 4(B) is an enlarged front view showing part IV of Figure 3. Figure 5 is a cross-sectional view along the line VV in Figure 4(B). C / L in Figure 5 indicates the center line of the tire width. The airless tire 1 of this embodiment is an example that does not have an intermediate ring 13 and is composed of a wheel 11, spokes 12, outer ring 14 and tread 15.

[0019] The spokes 12 in this embodiment are made of an elastic material such as an elastic thermoplastic resin or an elastic thermosetting resin, and are plate-shaped members having a width corresponding to the tire width. The spokes 12 in this embodiment extend radially from the outer circumference of the wheel 11 toward the inner circumference of the tread 15, and a plurality of spokes 12 are provided at equal intervals, spaced apart from each other, along the circumferential direction of the tire. The plurality of spokes 12 are provided axially symmetric with respect to the central axis of the tire.

[0020] As shown in Figures 4(A) and (B), each spoke 12 has a bent portion 16 formed between the wheel-side end and the tread-side end, which bends in the direction connecting these two ends. As shown in the figures, this spoke 12 is formed in a zigzag shape when viewed in the direction of the tire's rotation axis (Y-axis direction). In the case of the rightmost spoke 12 in Figure 4(B), five bent portions 16 are shown from the wheel-side end to the tread-side end 12b, and the same configuration of bent portions 16 is formed on each spoke 12 around the entire circumference of the tire.

[0021] If the degree of bending of the spoke 12 at the bent portion 16 is extremely small, the spoke 12 will buckle and deform between the bent portions, and will not deform at the bent portion 16, making it impossible to regulate the amount of deformation of the tire in the circumferential direction. Therefore, although there is no particular limit to the lower angle θ of the bent portion 16 shown in the figure, it is desirable to set it to less than 120°.

[0022] The spoke 12 of this embodiment is provided with a first rib 21 that extends radially along the tire along the extending direction of the spoke 12. The first rib 21 of this embodiment extends along the entire length of the spoke 12 and along the extending direction of the spoke 12. The first rib 21 is a reinforcing member or reinforcing portion that protrudes from the surface of the plate-shaped spoke 12, and may be formed integrally with the spoke 12 or may be formed separately and then joined. The first rib 21 may be provided on both the front and back surfaces of the spoke 12 or on only one surface. Figures 5(A) to (C) show the first rib 21 configured to protrude from both the front and back surfaces of the plate-shaped spoke 12. When the first rib 21 is configured to protrude from both the front and back surfaces of the plate-shaped spoke 12, the center of the first rib 21 may be aligned with the center in the thickness direction of the spoke 12, as shown in Figure 5(A) or (B), or the center of the first rib 21 may be eccentrically positioned from the center in the thickness direction of the spoke 12, as shown in Figure 5(C).

[0023] The cross-sectional shape of the first rib 21 in this embodiment is not particularly limited, and may be rectangular in addition to the circular or elliptical shapes shown in Figures 5(A) to (C). Also, although not shown, when the first rib 21 is configured to protrude from one main surface of the plate-shaped spoke 12, the cross-sectional shape of the first rib 21 may be rectangular in addition to a semicircular or semi-elliptical shape. However, forming the first rib 21 with a curved surface that curves and protrudes from the surface of the spoke 12, for example, in a circular or elliptical shape, has the advantage of suppressing stress concentration in the first rib 21.

[0024] In this embodiment, the first rib 21 serves to reinforce the spokes 12, so it is preferable that the second moment of area of ​​the first rib 21 in the radial direction of the tire be greater than the second moment of area of ​​the spokes 12 excluding the first rib 21. This increases the load-bearing capacity of the spokes 12, allowing it to withstand an even larger wheel load.

[0025] In this embodiment, the first rib 21 is preferably formed continuously along the entire length in the extending direction of the spoke 12. However, in the width direction of the spoke 12, as shown in Figure 5, it is preferable to provide multiple first ribs 21 spaced apart from each other, with shorter spacing towards the outside of the tire in the width direction (Y-axis direction) of the spoke 12. Providing multiple first ribs 21 further increases the load-bearing capacity of the spoke 12, allowing it to withstand an even larger wheel load. Furthermore, by providing multiple first ribs 21 spaced apart from each other, with shorter spacing towards the outside of the tire in the width direction of the spoke 12, that is, in driving scenarios where the steering wheel is turned and the vehicle turns, increasing the wheel load, the tire camber angle with respect to the ground often moves away from 0 (a camber angle occurs) due to the characteristics of the vehicle's suspension. In this case, a so-called uneven contact phenomenon occurs on the side of the tire in the width direction, resulting in a larger wheel load on the spokes 12 near the side of the tire. Even in such driving conditions, it is desirable that the first ribs 21 be arranged in greater numbers towards the outer edge of the tire width in order to prevent buckling of the spokes 12.

[0026] The first rib 21 of the present invention is not limited to the example shown in Figure 5, and one first rib 21 may be provided on a spoke 12. Figure 6 is a cross-sectional view corresponding to the cross-sectional view along the VV line in Figure 4(B), showing another example of the embodiment shown in Figure 5. C / L in Figure 6 indicates the center line of the tire width. When one first rib 21 is provided on a spoke 12, the position in the width direction of the spoke 12 is not particularly limited, but it is preferable to provide it at the center of the spoke 12 from the viewpoint of preventing twisting of the tire. Furthermore, the first rib 21 may be provided on both the front and back surfaces of the spoke 12 as shown in Figures 6(A) to (C), or on only one main surface. Moreover, the cross-sectional shape of the first rib 21 is not particularly limited, and examples include the rectangular shape shown in Figure 6(A), the circular shape shown in Figure 6(B), or the elliptical shape shown in Figure 6(C). Furthermore, although not shown in the figures, when the first rib 21 is configured to protrude from one main surface of the plate-shaped spoke 12, the cross-sectional shape of the first rib 21 may be semicircular, semielliptical, or rectangular. In particular, as shown in Figure 6(C), it is more preferable to provide a third rib 23 with a large cross-sectional area.

[0027] 《Second Embodiment》 Figure 7A is an enlarged perspective view of the portion of the airless tire 1 according to the second embodiment of the present invention that corresponds to part IV in Figure 3, and Figure 7B is a front view of a portion of the spoke 12 of the airless tire 1 according to the second embodiment. Figure 7B is a front view of the main surface of a portion of one spoke 12 located between two bent portions 16, and as shown in the figure, the left-right direction of the figure corresponds to the Y-axis direction (width direction of the tire), the up-down direction of the figure corresponds to the Z-axis direction (up-down direction of the tire), and the direction perpendicular to the plane of the paper corresponds to the X-axis direction (front-to-back direction of the tire).

[0028] The airless tire 1 of this embodiment further includes a second rib 22 extending in the width direction of the spoke 12. The second rib 22 of this embodiment is provided on the spoke 12 so as to connect a plurality of first ribs 21. The other configurations are the same as those of the first embodiment described above, so the same description of the configurations will be used here.

[0029] As shown in Figure 7B, the second rib 22 of this embodiment is provided to extend across the entire width of the spoke 12, connecting across the five first ribs 21. Furthermore, the second rib 22 of this embodiment is provided at a position close to the bent portion 16 of the spoke 12. Similar to the first rib 21, the second rib 22 is a reinforcing member or reinforcing portion that protrudes from the plate-shaped surface of the spoke 12, and may be formed integrally with the first rib 21 and / or the spoke 12, or it may be formed separately and then joined. The second rib 22 may be provided on both the front and back surfaces of the spoke 12, or on only one surface. However, since the second rib 22 is a reinforcing member that connects multiple first ribs 21 in the width direction, if it is provided on one main surface of the spoke 12, it must be provided on the main surface where the first rib 21 is provided. The cross-sectional shape of the second rib 22 of this embodiment is not particularly limited and may be circular, elliptical, or rectangular.

[0030] By providing the second rib 22 in this embodiment, the improvement in buckling strength due to the first rib 21 can be made even more uniform across the entire width direction of the tire. This further increases the buckling strength of the tire.

[0031] 《Third Embodiment》 Figure 8 shows an airless tire 1 according to a third embodiment of the present invention, where Figure 8(A) is an enlarged perspective view showing a part of the portion corresponding to part VIII of Figure 1, and Figure 8(B) is a front view. Figure 9 is a cross-sectional view along the line IX-IX in Figure 8(B). C / L in Figure 9 indicates the center line of the tire width. The airless tire 1 of this embodiment is the airless tire 1 of the second embodiment described above with the addition of elements such as an intermediate ring 13 and a third rib 23, and the explanation of the configuration common to the second embodiment will be incorporated herein.

[0032] First, the relationship between the intermediate ring 13 and the spokes 12 of the airless tire 1 according to the third embodiment will be explained. Figure 11A is an enlarged front view showing an enlarged portion of the airless tire according to the third embodiment of the present invention, corresponding to part IIIV in Figure 1.

[0033] The spokes 12 in this embodiment are made of an elastic material such as an elastic thermoplastic resin or an elastic thermosetting resin, and are plate-shaped members having a width corresponding to the tire width. The spokes 12 in this embodiment extend radially from the outer circumference of the wheel 11 toward the inner circumference of the tread 15, and a plurality of spokes are provided at equal intervals, spaced apart from each other, along the circumferential direction of the tire. The plurality of spokes 12 are provided axially symmetric with respect to the central axis of the tire. In the enlarged front view of the figure, three spokes 121, 122, and 123 are shown from right to left. The number of spokes 12 provided on a single airless tire 1 is not particularly limited and can be set appropriately according to the tire's contact length, the load capacity of the spokes 12, vibration resistance, and other required specifications of the tire.

[0034] Each spoke 12 has a bent portion 16 formed between the wheel-side end 12a and the tread-side end 12b, as indicated by the reference numerals 12a and 12b on the rightmost spoke 121 in Figure 11A. This bent portion 16 bends in the direction connecting these two ends 12a and 12b. As shown in the figure, this spoke 12 is formed in a zigzag shape when viewed in the direction of the tire's rotation axis (Y-axis direction). Specifically for the rightmost spoke 121 in the figure, five bent portions 161, 162, 163, 164, and 165 are formed from the wheel-side end 12a to the tread-side end 12b. Although the reference numerals for the bent portions 16 are only given to the rightmost spoke 121 in the figure, the same configuration of bent portions 16 is formed on each spoke 12 around the entire circumference of the tire.

[0035] If the degree of bending of the spoke 12 at the bent portion 16 is extremely small, the spoke 12 will buckle and deform between the bent portions, and will not deform at the bent portion 16, making it impossible to regulate the amount of deformation of the tire in the circumferential direction. Therefore, although there is no particular limit to the lower angle θ of the bent portion 16 shown in the figure, it is desirable to set it to less than 120°.

[0036] The intermediate ring 13 in this embodiment is made of an elastic material such as a thermoplastic resin or a thermosetting resin that has elasticity, similar to the spokes 12, and is provided between the wheel 11 and the tread 15, connected to a plurality of spokes 12. The intermediate ring 13 is cylindrical in shape, concentric with the wheel 11 and the tread 15, and having a width corresponding to the tire width. In the front view showing the basic configuration of Figure 1, two intermediate rings 13 are provided, but in the airless tire 1 of the third embodiment shown in Figure 11A, five intermediate rings 13 are provided. The number of intermediate rings 13 provided in one airless tire 1 is not particularly limited, but by setting the number of intermediate rings 13 to two, four, six, or other even numbers, the balance of forces in the circumferential direction of the tire is maintained. Therefore, the axial force (compressive force and tensile force) acting on the intermediate ring 13 becomes continuous throughout the circumference of the tire, and the load acting on the bent portion 16 of the spokes 12 can be distributed throughout the entire tire. As a result, the rolling resistance coefficient (RRC) is reduced.

[0037] As shown in Figure 1, one intermediate ring 13 is provided in an annular shape between the wheel 11 and the tread 15, and therefore intersects with multiple spokes 12. In the airless tire 1 of this embodiment, each intermediate ring 13 is connected to each spoke 12 at each bend 16. That is, as shown in the enlarged front view of Figure 11A, the intermediate ring 131 provided on the innermost circumference is connected to the bend 161 on the innermost circumference of each spoke 121, 122, 123, the intermediate ring 132 on the next inner circumference is connected to the bend 162 on the next inner circumference of each spoke 121, 122, 123, and the intermediate ring 135 provided on the outermost circumference is connected to the bend 165 on the outermost circumference of each spoke 121, 122, 123.

[0038] Furthermore, in the airless tire 1 of this embodiment, the bent portions 16 of the spokes 12 connected to the same intermediate ring 13 are formed to bend in the same direction with respect to the circumferential direction of the tire. That is, as shown in the enlarged front view of Figure 11A, looking at the intermediate ring 131 provided on the innermost circumference, the bending direction of the bent portions 161 of the three spokes 121, 122, and 123 connected to this intermediate ring 131 is convex to the left in the figure. Similarly, looking at the intermediate ring 132 provided on the next inner circumference, the bending direction of the bent portions 162 of the three spokes 121, 122, and 123 connected to this intermediate ring 132 is convex to the right in the figure.

[0039] As in this embodiment, if the bent portions 16 of the spokes 12 connected to the same intermediate ring 13 are formed to bend in the same direction with respect to the circumferential direction of the tire (i.e., the zigzag of the spokes 12 is set in phase), then the deformation direction of the bent portion 16 of the spokes 12 toward the circumferential direction will be the same for adjacent spokes 12. Looking at the intermediate ring 131 provided on the innermost circumference as shown in Figure 11A, the bending direction of the bent portions 161 of the three spokes 121, 122, and 123 connected to this intermediate ring 131 is all to the left, as indicated by the white arrows in the figure. Next, looking at the intermediate ring 132 provided on the inner circumference, the bending direction of the bent portions 162 of the three spokes 121, 122, and 123 connected to this intermediate ring 132 is all to the right, as indicated by the white arrows in the figure. Therefore, the axial force (compressive and tensile force) acting on the intermediate ring 13 becomes continuous throughout the entire circumference of the tire, and the load acting on the bent portion 16 of the spoke 12 can be distributed across the entire tire. As a result, the rolling resistance coefficient is reduced.

[0040] However, the spokes 12 according to the present invention are not limited to forming the bent portions 16 of the spokes 12 connected to the same intermediate ring 13 so that they bend in the same direction with respect to the circumferential direction of the tire (i.e., setting the zigzag of the spokes 12 in phase), as shown in Figure 11A. Figure 11B is an enlarged front view corresponding to part IIIV of Figure 1, showing another example of the airless tire 1 according to the third embodiment of Figure 11A.

[0041] In the airless tire 1 of the embodiment shown in Figure 11B, two adjacent spokes (for example, spokes 121 and 122, spokes 123 and 124 in Figure 11B) form a pair of spokes, and these pairs of spokes 12, 12 are provided at equal intervals around the entire circumference of the tire. In the airless tire 1 of this embodiment, as shown in Figure 11B, looking at the intermediate ring 131 provided on the innermost circumference, of the bent portions 161 of the four spokes 121, 122, 123, and 124 connected to this intermediate ring 131, the bending direction of the bent portion 161 of spokes 121 and 123 is convex to the left in Figure 11B, and the bending direction of the bent portion 161 of spokes 122 and 124 is convex to the right in Figure 11B. Similarly, looking at the intermediate ring 132 provided on the inner circumference, of the three spokes 121, 122, and 123 connected to this intermediate ring 132, the bending direction of the bending portion 161 of spokes 121 and 123 is convex to the right in Figure 11B, while the bending direction of the bending portion 161 of spokes 122 and 124 is convex to the left in Figure 11B.

[0042] As in this example, if the bent portion 16 of the spoke 12 connected to the same intermediate ring 13 is formed to bend in the opposite direction to the circumferential direction of the tire (i.e., the zigzag of the spoke 12 is set to an opposite or opposite phase), when a wheel load (vehicle weight) is applied to the tire, in addition to the load distribution effect due to load transmission by the intermediate ring 13, the radial rigidity of the spoke 12 near the center point of contact with the ground increases. As a result, the thickness of the spoke 12 and the intermediate ring 13 can be reduced, which has the advantage of achieving a lighter tire.

[0043] Next, we will return to Figures 8 and 9 and describe the characteristic configuration of the third embodiment. The intermediate ring 13 of this embodiment is provided with a third rib 23 that extends in the circumferential direction of the intermediate ring 13.

[0044] The third rib 23 in this embodiment extends along the circumferential direction of the intermediate ring 13, over its entire circumference (strictly speaking, excluding the bent portion 16 which is the connection portion with the spoke 12). The third rib 23 is a reinforcing member or reinforcing portion that protrudes from the surface of the plate-shaped intermediate ring 13, and may be formed integrally with the intermediate ring 13, or it may be formed separately and then joined. The third rib 23 may be provided on both the front and back surfaces of the intermediate ring 13, or on only one surface. Figures 9(A) to (C) show the third rib 23 configured to protrude from both the front and back surfaces of the plate-shaped intermediate ring 13. When the third rib 23 is configured to protrude from both the front and back surfaces of the plate-shaped intermediate ring 13, the center of the third rib 23 may be aligned with the center in the thickness direction of the intermediate ring 13, as shown in Figure 9(A) or (B), or the center of the third rib 23 may be eccentric to the center in the thickness direction of the intermediate ring 13, as shown in Figure 9(C).

[0045] The cross-sectional shape of the third rib 23 in this embodiment is not particularly limited, and may be rectangular in addition to the circular or elliptical shapes shown in Figures 9(A) to (C). Also, although not shown, when the third rib 23 is configured to protrude from one main surface of the plate-shaped intermediate ring 13, the cross-sectional shape of the third rib 23 may be rectangular in addition to a semicircular or semi-elliptical shape. However, forming the third rib 23 with a curved surface that curves and protrudes from the surface of the intermediate ring 13, for example, in a circular or elliptical shape, has the advantage of suppressing stress concentration in the third rib 23.

[0046] In this embodiment, the third rib 23 serves to reinforce the intermediate ring 13. Therefore, it is preferable that the second moment of area of ​​the third rib 23 in the circumferential direction of the tire be greater than the second moment of area of ​​the intermediate ring 13 excluding the third rib 23. This increases load transmission by the intermediate ring 13, thereby further enhancing the rigidity of the tire in the longitudinal direction.

[0047] In this embodiment, the third rib 23 is preferably formed continuously around the entire circumference of the intermediate ring 13, but in the width direction of the intermediate ring 13, it is preferable to provide multiple third ribs 23 spaced apart from each other at equal intervals, as shown in Figure 9. Providing multiple third ribs 23 further increases load transmission by the intermediate ring 13, thereby further increasing the rigidity of the tire in the longitudinal direction. In addition, providing multiple third ribs 23 spaced apart from each other at equal intervals suppresses the occurrence of a lateral slip angle in the tire. As a result, when the tire is deformed vertically due to wheel load (such as in straight-line driving), the third rib 23 does not generate lateral force on the tire or moment in the steering direction of the tire, resulting in excellent straight-line stability of the vehicle (residual lateral force can be reduced to zero).

[0048] The third rib 23 of the present invention is not limited to the example shown in Figure 9, and one third rib 23 may be provided on the intermediate ring 13. Figure 10 is a cross-sectional view corresponding to the cross-sectional view along the line IX-IX in Figure 8(B), showing another example of the embodiment shown in Figure 9. C / L in Figure 10 indicates the center line of the tire width. When one third rib 23 is provided on the intermediate ring 13, the position of the intermediate ring 13 in the width direction is not particularly limited, but it is preferable to provide it at the center of the intermediate ring 13 from the viewpoint of preventing twisting of the tire. Furthermore, the third rib 23 may be provided on both the front and back surfaces of the intermediate ring 13 as shown in Figures 10(A) to (C), or on only one main surface. Moreover, the cross-sectional shape of the third rib 23 is not particularly limited, and examples include the rectangular shape shown in Figure 10(A), the circular shape shown in Figure 10(B), or the elliptical shape shown in Figure 10(C). Furthermore, although not shown in the figures, when the third rib 23 is configured to protrude from one main surface of the plate-shaped intermediate ring 13, the cross-sectional shape of the third rib 23 may be semicircular, semielliptical, or rectangular. In particular, as shown in Figure 10(C), it is more preferable to provide a single third rib 23 with a large cross-sectional area.

[0049] The airless tire 1 of this embodiment includes a first rib 21 provided on the spoke 12, a second rib 22 provided on the intermediate ring 13, and a third rib 23 also provided on the intermediate ring 13. The relationship between these three ribs is not particularly limited, but it is more preferable that the cross-sectional area S2 of the section perpendicular to the extension direction of the second rib 22 is set to be larger than the cross-sectional area S1 of the section perpendicular to the extension direction of the first rib 21 and the cross-sectional area S3 of the section perpendicular to the extension direction of the third rib 23 (S2>S1, S2>S3). Figure 11C is a perspective view showing an enlarged portion of the airless tire 1 of this embodiment, corresponding to part VIII of Figure 1, where the first rib 21, the second rib 22, and the third rib 23 all have a circular cross-sectional shape, and their diameters (corresponding to the height of the ribs) are ds, dw, and dr, respectively.

[0050] The second rib 22 transmits the effects of the first rib 21 and the third rib 23 to the entire tire, preventing localized stress loads and deformations, and enhancing the effects of the first rib 21 and the third rib 23. Therefore, by making the diameter dw of the second rib 22 larger than the diameter ds of the first rib 21 and the diameter dr of the third rib 23, and by making the cross-sectional area S2 of the second rib 22 larger than the cross-sectional area S1 of the first rib 21 and the cross-sectional area S3 of the third rib 23, the effect is further enhanced.

[0051] In addition, in the airless tire 1 according to the third embodiment, the second rib 22 may be omitted, and the airless tire 1 may be configured to have a first rib 21 provided on the spoke 12 and a third rib 23 provided on the intermediate ring 13.

[0052] 《Embodiment for Manufacturing Airless Tires》 When the airless tire 1 according to the first to third embodiments described above is mainly composed of resin material, it can be manufactured by injection molding using an injection molding apparatus or by a manufacturing method using an additive manufacturing apparatus.

[0053] In particular, at least the spokes 12 including the first rib 21 and the intermediate ring 13 including the third rib 23 can be manufactured using an injection molding apparatus including a mold, and the portion including the first rib 21 and the third rib 23 can be manufactured using a movable mold that is movable in the radial and widthwise directions of the tire. Figure 12 is a diagram showing an embodiment of the method for manufacturing an airless tire according to the present invention, where Figure 12(A) is a front view of the mold including the tire, and Figure 12(B) is a cross-sectional view along the BB line of Figure 12(A). Here, a method for manufacturing an airless tire in which only the first rib 21 is provided on the spokes 12 will be described.

[0054] In a structure having multiple rib shapes that protrude from the surface of the plate-shaped spokes 12, it is not possible to remove the mold from the molding die, and therefore, injection molding cannot be performed using two molding dies that clamp and unclamp from both sides of the tire, as in the conventional method. For this reason, in this embodiment, in order to enable removal of the first rib 21 portion, injection molding is performed using a molding die that can move in the width direction or the radial direction of the tire.

[0055] As shown in Figure 12(B), the mold of this embodiment comprises a fixed mold J1 and a first movable mold J2 that moves in the width direction of the tire, approaching and moving away from the fixed mold J1, and further comprises a second movable mold J3 provided on the first movable mold J2, which moves in the radial direction of the tire. As shown in Figure 12(A), the fixed mold J1 and the first movable mold J2 are molds for forming cavities in the portion to be formed into the spoke 12 and the portion to be formed into the outer ring 14, respectively, while the second movable mold J3 is a mold for forming a cavity in the portion to be formed into the first rib 21.

[0056] To integrally injection mold the spoke 12 having the first rib 21 and the outer ring 14, a fixed mold J1, a first movable mold J2, and a second movable mold J3 are positioned at the molding position of the injection molding apparatus. Then, the injection molding material M, fixed mold J1, first movable mold J2, and second movable mold J3 are heated to predetermined temperatures. When injection molding is ready, the heated and pressurized injection molding material M1 is injected from the gate of the fixed mold J1 into the cavity. Once the molding material M in the cavity has cooled and hardened, the first movable mold J2 is opened relative to the fixed mold J1. At this time, the molded product is held by the first movable mold J2, so the molded product is demolded by opening the second movable mold J3. At this point, the fixed mold J1 shown in Figure 12(A) is detached from the molded product, making it possible to move the second movable mold J3 in the radial direction of the tire. Thus, an airless tire having the first rib 21 can be manufactured by injection molding.

[0057] Furthermore, airless tires 1 with a second rib 22 on the spoke 12 or airless tires 1 with a third rib 23 on the intermediate ring 13 can also be manufactured in the same manner by providing a second movable J3 corresponding to the second rib 22 or third rib 23.

[0058] As in the airless tire 1 according to the third embodiment described above, when the first rib 21 and the second rib 22 are provided on the spoke 12, and the third rib 23 is provided on the intermediate ring 13, the structure of the molding die becomes complex even when a movable die is used because there are many possible demolding directions. For this reason, it is not easy to manufacture by injection molding. In such cases, it is preferable to manufacture the airless tire 1 by a manufacturing method using an additive manufacturing apparatus. Figure 13 is a perspective view of a tire showing another embodiment of the method for manufacturing an airless tire according to the present invention.

[0059] An additive manufacturing device, although not shown in the diagram, is a so-called three-dimensional manufacturing device (also called a 3D printer), which extrudes thermosetting resin or photocurable resin from a nozzle and repeatedly forms layers by controlling the ON / OFF state of the resin while moving the nozzle along the shape of the airless tire 1 to be molded. It comprises a nozzle that extrudes the molding material while controlling the ON / OFF state, and a manipulator that moves the nozzle in three-dimensional space.

[0060] In the manufacturing example shown in Figure 13, the spokes 12 including the first rib 21 and the second rib 22, the intermediate ring 13 including the third rib 23, and the outer ring 14 are manufactured using this type of additive manufacturing apparatus. The process of sequentially moving the nozzle in the circumferential direction of the airless tire 1 to form layers is repeated, thereby stacking multiple layers in the direction of the tire's rotation axis. By forming layers by moving the nozzle in the circumferential direction in this way, the radial accuracy of the tire (e.g., vertical runout RRO = Radial Run Out) is improved, and vibrations when the tire rotates can be suppressed.

[0061] Figure 14 is a plan view of a tire showing yet another embodiment of the method for manufacturing an airless tire according to the present invention. In the manufacturing method shown in Figure 13, layers were formed by sequentially moving the nozzle of the additive manufacturing apparatus in the circumferential direction of the airless tire 1 (see "direction of nozzle movement" in Figure 13). However, as shown in Figure 14, layers may be formed by moving the nozzle in a linear direction within the circumferential plane of the tire, and multiple layers may be stacked in the direction of the rotation axis of the tire. In this case, as shown in Figures 14(A) and (B), if the linear direction is different for the Nth layer and the N+1th layer, the directivity of strength caused by the manufacturing direction during production is eliminated, and the occurrence of areas with locally inferior strength can be prevented. As a result, variations in radial stiffness of the tire can be reduced, and vibrations when the tire rotates can be suppressed.

[0062] 《Effects and Functions of the Embodiment》 As described above, in this embodiment, the airless tire 1 is provided with a first rib 21 on the spoke 12 that extends radially along the direction in which the spoke extends, thereby increasing the load-bearing capacity of the spoke 12. As a result, the buckling strength against radial loads on the tire is increased, and it can withstand large wheel loads.

[0063] Furthermore, in the airless tire 1 of this embodiment, the first rib 21 is provided on the spokes 12 such that the second moment of area of ​​the first rib 21 in the radial direction of the tire is greater than the second moment of area of ​​the spokes 12 excluding the first rib 21. This increases the buckling strength against radial loads on the tire, allowing it to withstand even larger wheel loads.

[0064] Furthermore, in the airless tire 1 of this embodiment, the first rib 21 has a curved cross-section that protrudes from the surface of the spoke 12, so that stress concentration on the first rib 21 can be suppressed.

[0065] Furthermore, in the airless tire 1 of this embodiment, since the first ribs 21 are provided in multiple locations spaced apart in the width direction of the spokes 12, the buckling load of the spokes is increased, and the entire tire can share the wheel load.

[0066] Furthermore, in the airless tire 1 of this embodiment, the first rib 21 is provided at shorter intervals towards the outside of the tire with respect to the width direction of the spokes 12, so that even if a camber angle occurs in the tire, a large load can be received on the outside of the tire.

[0067] Furthermore, the airless tire 1 of this embodiment is provided with a second rib 22 that is attached to the spoke 12 to connect a plurality of first ribs 21 and extends in the width direction of the spoke 12. This allows the improvement in buckling strength by the first ribs 21 to be made even more uniform across the entire width direction of the tire. As a result, the buckling strength of the tire can be further increased.

[0068] Furthermore, the airless tire 1 of this embodiment is further equipped with an elastic intermediate ring 13 that is provided between the wheel 11 and the tread 15, concentrically with the outer ring 14 and connected to a plurality of spokes 12. Therefore, when the spokes 12 deform radially due to the wheel load of the tire, they are held in place by the intermediate ring 13, and the entire tire can deform vertically to hold the wheel load.

[0069] Furthermore, in this embodiment, the airless tire 1 is provided with a third rib 23 extending in the circumferential direction of the intermediate ring 13. This increases the rigidity of the intermediate ring 13, and increases the circumferential load transmission by the intermediate ring 13 when the spokes 12 near the contact patch deform in the circumferential direction. As a result, local deformation, including buckling deformation of the tire, can be suppressed, and the vertical rigidity of the tire can be reduced. In addition, since the entire tire deforms in the circumferential direction in response to a longitudinal load on the contact patch, the effect of increasing the circumferential rigidity of the tire is increased. This makes it possible to increase the longitudinal rigidity of the tire while simultaneously optimizing the vertical rigidity of the tire.

[0070] Furthermore, in the airless tire 1 of this embodiment, the cross-sectional area S2 of the section perpendicular to the extension direction of the second rib 22 is larger than the cross-sectional area S1 of the section perpendicular to the extension direction of the first rib 21 and the cross-sectional area S3 of the section perpendicular to the extension direction of the third rib 23. The second rib 22 transmits the effects of the first rib 21 and the third rib 23 to the entire tire, prevents localized stress loads and deformations, and is responsible for increasing the effects of the first rib 21 and the third rib 23. Therefore, by making the cross-sectional area S2 of the second rib 22 larger than the cross-sectional area S1 of the first rib 21 and the cross-sectional area S3 of the third rib 23, the effect is further enhanced.

[0071] Furthermore, in the airless tire 1 of this embodiment, the third rib 23 is provided on the intermediate ring 13 such that the second moment of area of ​​the third rib 23 in the circumferential direction of the tire is greater than the second moment of area of ​​the intermediate ring 13 excluding the third rib 23. As a result, the load transmission by the third rib 23 is greater than the load transmission by the intermediate ring 13 excluding the third rib 23. Consequently, the load transmission by the intermediate ring 13 is further increased, and the rigidity of the tire in the longitudinal direction can be further enhanced.

[0072] Furthermore, in the airless tire 1 of this embodiment, the third rib 23 has a curved cross-section that protrudes from the surface of the intermediate ring 13, which helps to suppress stress concentration on the third rib 23.

[0073] Furthermore, in the airless tire 1 of this embodiment, since the third ribs 23 are provided in multiple locations spaced apart in the width direction of the intermediate ring 13, the load transmission by the intermediate ring 13 is further increased, and the rigidity of the tire in the longitudinal direction can be further enhanced.

[0074] Furthermore, in the airless tire 1 of this embodiment, the third rib 23 is provided at equal intervals in the width direction of the intermediate ring 13, which suppresses the occurrence of a lateral slip angle in the tire. As a result, when the tire is deformed vertically due to the wheel load (such as in straight-line driving), the third rib 23 prevents the generation of lateral forces on the tire and moments in the steering direction of the tire, resulting in excellent straight-line stability of the vehicle (residual lateral force can be reduced to zero).

[0075] Furthermore, in the airless tire 1 of this embodiment, the spokes 12 are formed in a zigzag shape when viewed in the direction of the tire's rotation axis. Therefore, when the spokes 12 deform in the radial direction, an effect is created that causes the intermediate ring 13 to rotate in the circumferential direction, thus allowing the entire tire to share the wheel load.

[0076] Furthermore, in the airless tire 1 of this embodiment, the bent portion 16 of the spoke 12 connected to the same intermediate ring 13 is formed to bend in the same direction with respect to the circumferential direction of the tire. As a result, the radial deformation of the spoke 12 increases the rotational effect of the intermediate ring 13 in the same circumferential direction, allowing the entire tire to share the wheel load more effectively.

[0077] Furthermore, in the airless tire 1 of this embodiment, the bent portions 16 of two adjacent spokes 12 connected to the same intermediate ring 13 in the circumferential direction of the tire are formed to bend in opposite directions to the circumferential direction of the tire. As a result, the radial rigidity of the spokes 12 near the ground appears to be higher, and the load can be held even under large wheel loads.

[0078] Furthermore, the manufacturing method of the airless tire 1 in this embodiment uses at least a spoke 12 including a first rib 21 and an intermediate ring 13 including a third rib 23, and an injection molding apparatus including a mold, so it can be manufactured in a short time and at low cost.

[0079] Furthermore, in the manufacturing method of the airless tire 1 of this embodiment, the portion including the first rib 21 and the third rib 23 is manufactured using a movable mold that can move in the radial direction and the width direction of the tire, so that an airless tire 1 having multiple ribs can be manufactured.

[0080] Furthermore, in this embodiment, at least the spokes 12 including the first rib 21 and the intermediate ring 13 including the third rib 23 are manufactured using an additive manufacturing apparatus that extrudes material M from a nozzle. The process of sequentially moving the nozzle in the circumferential direction of the tire to form layers is repeated, and multiple layers are stacked in the direction of the tire's rotation axis. This makes it possible to manufacture an airless tire 1 with complex and fine ribs. In addition, by moving the nozzle in the circumferential direction to form layers, the radial accuracy of the tire (e.g., vertical runout RRO = Radial Run Out) is improved, and vibrations when the tire rotates can be suppressed.

[0081] Furthermore, in this embodiment, at least the spokes 12 including the first rib 21 and the intermediate ring 13 including the third rib 23 are manufactured using an additive manufacturing apparatus that extrudes material M from a nozzle. The process of forming layers by moving the nozzle in a linear direction within the circumferential surface of the tire is repeated, with each layer having a different linear direction. Multiple layers are then stacked in the direction of the tire's rotation axis, making it possible to manufacture an airless tire 1 with complex and fine ribs. In addition, the directionality of strength caused by the manufacturing direction is eliminated, preventing the occurrence of areas with locally inferior strength. As a result, variations in radial stiffness of the tire are reduced, and vibrations when the tire rotates can be suppressed. [Explanation of Symbols]

[0082] 1…Airless tires 11... Wheels 111…Disk 112... Rim 113...Groove 12 spokes 12a... Wheel-side end 12b...Tread side end 13…Intermediate ring 14…Outer ring 15...Tread 16...Bend 21…First rib 22…2nd rib 23…Third Rib

Claims

1. An elastic outer ring is positioned on the inner circumference of the tread that contacts the road surface, Multiple elastic spokes are arranged radially from the outer circumference of the wheel attached to the vehicle toward the outer ring, The spoke is provided with a first rib that extends radially along the direction in which the spoke extends, An airless tire in which the first rib is provided on the spoke such that the second moment of area of ​​the first rib in the radial direction of the tire is greater than the second moment of area of ​​the spokes excluding the first rib.

2. The airless tire according to claim 1, wherein the first rib has a curved cross-section that protrudes from the surface of the spoke.

3. The airless tire according to claim 1, wherein the first ribs are provided in multiple locations spaced apart in the width direction of the spokes.

4. The airless tire according to claim 1, wherein the first ribs are provided at shorter intervals on the outer side of the tire with respect to the width direction of the spokes.

5. The airless tire according to claim 3, further comprising a second rib provided on the spoke to connect a plurality of the first ribs and extending in the width direction of the spoke.

6. The airless tire according to claim 1, further comprising an elastic intermediate ring provided between the wheel and the tread, concentrically with the outer ring and connected to the plurality of spokes.

7. Between the wheel and the tread, an elastic intermediate ring is provided concentrically with the outer ring and connected to the plurality of spokes, The intermediate ring is further provided with a third rib that extends in the circumferential direction of the intermediate ring, The airless tire according to claim 5, wherein the area of ​​the cross-section perpendicular to the extension direction of the second rib is greater than the area of ​​the cross-section perpendicular to the extension direction of the first rib and the area of ​​the cross-section perpendicular to the extension direction of the third rib.

8. The intermediate ring is provided with a third rib that extends in the circumferential direction of the intermediate ring, The airless tire according to claim 6, wherein the third rib is provided on the intermediate ring such that the second moment of area of ​​the third rib in the circumferential direction of the tire is greater than the second moment of area of ​​the intermediate ring excluding the third rib.

9. The intermediate ring is provided with a third rib that extends in the circumferential direction of the intermediate ring, The airless tire according to claim 6, wherein the third rib has a curved cross-section that protrudes from the surface of the intermediate ring.

10. The intermediate ring is provided with a third rib that extends in the circumferential direction of the intermediate ring, The airless tire according to claim 6, wherein the third ribs are provided in multiple locations spaced apart in the width direction of the intermediate ring.

11. The airless tire according to claim 10, wherein the third ribs are provided at equal intervals in the width direction of the intermediate ring.

12. The airless tire according to any one of claims 1 to 11, wherein the spokes are formed in a zigzag shape when viewed in the direction of the rotation axis of the tire.

13. The airless tire according to claim 12, wherein the bent portion of the spoke connected to the same intermediate ring is formed to bend in the same direction with respect to the circumferential direction of the tire.

14. The airless tire according to claim 12, wherein the bent portions of two adjacent spokes in the circumferential direction of the tire, which are connected to the same intermediate ring, are formed to bend in opposite directions with respect to the circumferential direction of the tire.

15. A method for manufacturing an airless tire according to any one of claims 7 to 11, A method for manufacturing an airless tire, wherein at least the spoke including the first rib or the intermediate ring including the third rib is manufactured using an injection molding apparatus including a mold.

16. The method for manufacturing an airless tire according to claim 15, wherein the portion including the first rib and the third rib is manufactured using a movable mold that is movable in the radial direction and the width direction of the tire.

17. A method for manufacturing an airless tire according to any one of claims 7 to 11, At least the spoke including the first rib and the intermediate ring including the third rib are manufactured using an additive manufacturing apparatus that extrudes material from a nozzle. A method for manufacturing an airless tire, comprising repeatedly moving the nozzle sequentially in the circumferential direction of the tire to form layers, thereby stacking multiple layers in the direction of the tire's rotation axis.

18. A method for manufacturing an airless tire according to any one of claims 7 to 11, At least the spoke including the first rib and the intermediate ring including the third rib are manufactured using an additive manufacturing apparatus that extrudes material from a nozzle. A method for manufacturing an airless tire, comprising repeatedly moving the nozzle in a linear direction within the circumferential surface of the tire to form layers, varying the linear direction for each layer, and stacking multiple layers in the direction of the tire's rotation axis.

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