Airless tire structure

Abstract

To provide an airless tire that can avoid a non-uniform contact pressure distribution as in a conventional airless tire structure.SOLUTION: An airless tire includes a structure in which a plurality of spoke sections 6 radially arranged are connected to at least one intermediate ring section 7 forming a concentric circle at the midpoint of the spoke sections 6 with respect to the center of the tire. The spoke sections 6 arranged in the circumferential direction in a plurality of rows are provided in a plurality of rows in the tire width direction, and two rows of the spoke sections 6 adjacent to each other are arranged offset in the circumferential direction, and thus an airless tire structure is achieved, which realizes a uniform contact pressure distribution while ensuring rigidity.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an airless tire structure for use on vehicle wheels. [Background technology]

[0002] Conventionally, an airless tire is disclosed, for example, in Patent Document 1. Patent Document 1 describes a non-pneumatic tire equipped with a support structure. The support structure has an inner annular portion, an intermediate annular portion, and an outer annular portion arranged concentrically, and has a structure including a plurality of inner connecting portions connecting the inner annular portion and the intermediate annular portion, and a plurality of outer connecting portions connecting the intermediate annular portion and the outer annular portion. In this non-pneumatic tire, the inner and outer connecting portions are arranged radially like spokes, making it difficult for stiffness fluctuations to occur depending on the positional relationship between the spoke positions and the center position of the contact patch. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-35050 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the conventional airless tire structure described above, there is a tendency for the ground contact pressure to be relatively high at the spoke positions and relatively low between the spoke positions, resulting in uneven ground contact pressure distribution, and improvements were desired.

[0005] The present invention has been made in consideration of the above-mentioned conventional situation, and has an object to provide an airless tire structure that can achieve uniform ground pressure distribution while ensuring rigidity. [Means for solving the problem]

[0006] The airless tire structure according to the present invention has a structure in which a plurality of radially arranged spoke parts are connected to at least one intermediate ring part that is concentrically arranged at the middle of the spoke parts with respect to the tire center. The airless tire structure is characterized in that it has a plurality of rows of spoke parts aligned in the circumferential direction in the tire width direction, and the spoke parts of two adjacent rows are offset from each other in the circumferential direction. Effect of the Invention

[0007] The airless tire structure according to the present invention ensures a desired rigidity by connecting the spoke portions and the intermediate ring portion to each other, and by arranging the spoke portions of two adjacent rows with an offset from each other in the circumferential direction, the spoke portions of the adjacent rows compensate for the drop in ground pressure between the circumferentially adjacent spoke portions. In this way, the airless tire structure can achieve a uniform ground pressure distribution while ensuring rigidity. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a side view with an enlarged view showing a first embodiment of an airless tire. [Diagram 2] FIG. 2 is a perspective view of the airless tire shown in FIG. [Diagram 3] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 4] FIG. 2 is a side view of a main part of an airless tire in a deformed state. [Diagram 5] FIG. 4 is a cross-sectional view of a main portion of a second embodiment of an airless tire. [Figure 6] FIG. 11 is a cross-sectional view of a main portion of a third embodiment of an airless tire. [Figure 7] FIG. 11 is a cross-sectional view of a main portion of a fourth embodiment of an airless tire. [Figure 8] FIG. 11 is a cross-sectional view of a main portion of a fifth embodiment of an airless tire. [Figure 9] FIG. 11 is a cross-sectional view of a main portion of a sixth embodiment of an airless tire. [Figure 10]FIG. 10 is an enlarged perspective view of a portion of the airless tire shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] First Embodiment The airless tire T shown in FIG. 1 has a structure including a support structure 3 between a wheel 1 connected to an axle and a tread ring 2 for contact with the ground. The wheel 1 is made of a highly rigid material such as metal. The tread ring 2 is preferably a composite structure containing reinforcing fibers such as steel cords. The support structure 3 is mainly made of a material having elasticity such as rubber or resin, and existing materials such as thermoplastic resin or thermosetting resin can be used.

[0010] The support structure 3 has substantially the characteristics of the airless tire structure according to the present invention, and includes an inner connecting ring portion 4 arranged on the outer periphery of the wheel 1, and an outer connecting ring portion 5 arranged on the inner periphery of the tread ring 2. The support structure 3 has a structure in which a plurality of spoke portions 6 arranged radially around the wheel 1 and at least one intermediate ring portion 7 forming a concentric shape at the middle of the spoke portions 6 with respect to the tire center are connected to each other.

[0011] Each spoke portion 6 has an end portion on the tire center side connected to the inner connecting ring portion 4 and an end portion on the anti-center side connected to the outer connecting ring portion 5, and in the illustrated example, is disposed at equal intervals in the circumferential direction and forms a zigzag shape in the radial direction. In addition, the support structure 3 has a plurality of (five in the illustrated example) intermediate ring portions 7 equally spaced between the inner connecting ring portion 4 and the outer connecting ring portion 5.

[0012] The ring portions 4, 5, and 7 are arranged concentrically about the tire center, and there is space between the ring portions and between the spoke portions 6. The ring portions 4, 5, and 7 and the spoke portions 6 may be connected to each other by being integrated or by bonding separate parts, and may be made of the same material or different materials. Bonding separate parts may be done by mechanical bonding, bonding with an adhesive, or the like.

[0013] Furthermore, the support structure (airless tire structure) 3 has multiple rows of spoke portions 6 aligned in the circumferential direction in the tire width direction, and in this embodiment has four rows of spoke portions 6. As shown in Fig. 2, the support structure 3 has an intermediate ring portion 7 that is divided into multiple (four) split rings 7A equal in number to the number of rows of spoke portions 6, and one row of spoke portions 6 is disposed in each split ring 7A.

[0014] As shown in Fig. 3, the support structure 3 has two rows of spoke portions 6, 6 adjacent to each other in the tire width direction offset from each other in the circumferential direction. In Fig. 3, the up-down direction is the circumferential direction, and the left-right direction is the tire width direction. In the example shown in Fig. 3, the spoke portions 6 are arranged in the same phase on the first and third split rings 7A from the left, and similarly the spoke portions 6 are arranged in the same phase on the second and fourth split rings 7A, and the offset amount between the two rows of spoke portions 6, 6 adjacent to each other in the tire width direction is approximately half the distance between the spoke portions 6 adjacent to each other in the circumferential direction.

[0015] In the above-mentioned support structure 3, at least the spoke portion 6 and the intermediate ring portion 7 are divided in the tire width direction, and the inner and outer connecting rings 4, 5 may be formed into a continuous annular shape in the tire width direction. Since the tread ring 2 is for contact with the ground, it is desirable that it is an integral annular member that is continuous in the tire width direction.

[0016] Furthermore, as described above, in the above-mentioned support structure 3, a row of spoke portions 6 are arranged in each split ring 7A constituting the intermediate ring portion 7, and the dimension W of the split ring 7A in the tire width direction varies periodically in the tire circumferential direction with a maximum Wmax at the position of the spoke portion 6, and a gap S is provided between adjacent split rings 7A, 7A.

[0017] As shown in FIG. 3, the support structure 3 is designed so that when the width dimension of the spoke portion 6 in the tire width direction is I, the width dimension of the tire is L, and the number of rows of the spoke portion 6 in the tire width direction is N, these satisfy the relationship I≧L / N.

[0018] The support structure 3 has a structure in which the split rings 7A, 7A adjacent to each other in the tire width direction have a gap S between them and come into contact with each other under a lateral load of 40% or more of the vehicle wheel load. This structure can be set by adjusting the elasticity and dimensions of the material forming the support structure 3, the size of the gap S, etc.

[0019] In the airless tire structure having the above configuration, when the wheel load of the vehicle is applied, adjacent split rings 7A deform in different modes as shown in FIG. 4. However, by employing split rings 7A whose width dimension changes as shown in FIG. 3, contact and interference between adjacent split rings 7A can be avoided.

[0020] In the above airless tire structure, when the spoke portion 6 is compressed and deformed in the tire radial direction at the contact portion, the split ring 7A also deforms at the same time, and the adjacent spoke portion 6 also deforms in accordance with the deformation of the split ring 7A, thereby propagating the load in the circumferential direction and supporting the load throughout the tire. At this time, if there was no intermediate ring portion, the spoke portion 6 would undergo large buckling deformation. In contrast, in the above airless tire structure, the load propagation action of the intermediate ring portion 7 suppresses large deformation due to buckling of the spoke portion 6.

[0021] Furthermore, in the above airless tire structure, as shown by the solid arrows in the enlarged view in Fig. 1, the ground pressure is relatively high where the spoke portions 6 are arranged, and relatively low where there are no spoke portions 6. The symbol G in the enlarged view indicates the ground. In this case, in the above airless tire structure, the spoke portions 6, 6 in two circumferentially adjacent rows are offset from each other in the circumferential direction, so that the drop in ground pressure between the circumferentially adjacent spoke portions 6, 6 is compensated for by the spoke portions 6 in the adjacent rows, as shown by the dotted arrows in the enlarged view in Fig. 1, and the locations where the spoke portions 6 with high ground pressure are arranged are dispersed over the entire contact patch.

[0022] In this way, the above airless tire structure can ensure rigidity through the spoke portions 6 and the intermediate ring portion 7, while achieving a uniform ground contact pressure distribution through the dispersed arrangement of the spoke portions 6.

[0023] Furthermore, in the above airless tire structure, by setting the relationship between the width dimension I of the spoke portion 6, the width dimension L of the tire, and the number of rows N of the spoke portion 6 to be I≧L / N, in addition to the above effects, the airless tire structure can ensure a large width dimension I of the spoke portion 6. This enables the airless tire structure to improve the tire lateral rigidity, which contributes to handling performance.

[0024] Furthermore, by making the gap S between adjacent split rings 7A and spoke portions 6 in the width direction about 10% of the width dimension I of the spoke portion 6, a structure is obtained in which the split rings 7A come into contact with each other and improve lateral rigidity when a lateral force of 40% or more of the ground load is applied. Such a structure is preferable from the viewpoint of cornering performance.

[0025] Furthermore, in the above airless tire structure, the intermediate ring portion 7 is composed of a plurality of split rings 7A divided into the same number as the number of rows of spoke portions 6, and one row of spoke portions 6 is arranged in each split ring 7. The split rings 7A equipped with the spoke portions 6 can be integrated, for example, by resin molding or the like. As a result, in the above airless tire structure, it is possible to manufacture the airless tire 1 by producing a plurality of split rings 7A equipped with the spoke portions 6 and combining these so that the spoke portions 6, 6 are arranged offset from each other, which can contribute to reducing the number of steps and costs in manufacturing.

[0026] Furthermore, the above-described airless tire structure is configured so that the split rings 7A, 7A adjacent to each other in the tire width direction come into contact with each other under a lateral load of 40% or more of the vehicle's wheel load. This increases the tire's lateral rigidity when the vehicle turns with a lateral acceleration equal to or greater than a certain level, thereby improving cornering performance.

[0027] Figures 5 to 10 are diagrams showing second to sixth embodiments of the airless tire structure according to the present invention, and Figures 5 to 9 are diagrams showing cross sections of essential parts based on line AA in Figure 1. In the following embodiments, the same components as in the first embodiment are given the same reference numerals, and detailed explanations will be omitted.

[0028] <Second embodiment> The airless structure shown in FIG. 5 has a basic configuration equivalent to that of the first embodiment (see FIG. 3), and has a configuration in which the width dimension I of the spoke portion 6 is I=L / N×1.1. That is, the airless tire structure can improve the lateral rigidity and cornering performance by increasing the width dimension I of the spoke portion 6. In the airless tire structure shown in FIG. 5, the width dimension of the split ring 7A is smaller than that of the first embodiment (see FIG. 3), so that the load transmission action in the circumferential direction of the split ring 7A is smaller, and the ground contact pressure distribution tends to become non-uniform. If this ground contact pressure distribution is uniform, the maximum lateral force during steering, which is one of the tire cornering performance factors, increases. Also, if the rigidity is higher, the tire's responsiveness until the generation of lateral force improves.

[0029] Therefore, in the above airless tire structure, the balance between rigidity and uniformity of ground pressure distribution can be adjusted by changing design variables such as the width dimension of the spoke portion 6 to match the required tire characteristics.

[0030] In the airless tire structure, the spoke portion 6 has the role of supporting the load and ensuring tire rigidity, and the intermediate ring portion 7 (split ring 7A) has the role of transmitting the load in the tire circumferential direction. When the width dimension I of the spoke portion 6 is large, the tire lateral rigidity is improved. It is desirable that the ratio of the width dimension I of the spoke portion 6 to the tire width dimension L and the number of rows N in the width direction is N·I / L=100% to 120%.

[0031] <Third embodiment> The airless tire structure shown in Fig. 6 is a structure in which the width dimension of the spoke portions 6 differs between the outer side and the inner side of the vehicle, with the width dimension Io of the spoke portions 6 arranged on the outer side of the vehicle, which is the left side in Fig. 6, being larger than the width dimension Ii of the spoke portions 6 arranged on the inner side of the vehicle. In the case of a structure in which there are four rows of spoke portions 6 as in the illustrated example, the width dimension I of the spoke portions 6 of each row may be gradually reduced in the direction from the outer side to the inner side of the vehicle, or a larger-smaller relationship may be set only for the width dimensions of selected rows.

[0032] When a vehicle turns, a lateral load is applied to the tire, and in particular, tires on the outer side in the turning direction tend to deform more on the outer side than on the tire center. In response to this, the above airless tire structure increases the width dimension I of the spoke portion 6 on the outer side of the vehicle, thereby improving the section modulus of the spoke portion 6 against the lateral load, effectively increasing the tire's lateral rigidity and contributing to improved tire durability. The above airless tire structure can also be applied to a configuration of an intermediate ring portion 7 that is continuous in the tire width direction (see FIG. 7).

[0033] <Fourth embodiment> In the airless tire structure shown in FIG. 7, the intermediate ring portion 7 is not divided in the tire width direction but is continuous in the tire width direction, and all rows of spoke portions 6 are arranged in the intermediate ring portion 7.

[0034] The above airless tire structure can obtain the same effects as the first embodiment, and in addition, because the split rings do not come into contact with or interfere with each other, it is possible to achieve uniform ground pressure while ensuring rigidity, and the tire can be manufactured by additive manufacturing using a 3D printer, for example.

[0035] <Fifth embodiment> The airless tire structure shown in FIG. 8 has a configuration similar to that of the third embodiment (see FIG. 6), in which the width dimension of the spoke portion 6 differs between the outside and inside of the vehicle, and the width dimension Io of the spoke portion 6 located on the outside of the vehicle, which is the left side in FIG. 8, is larger than the width dimension Ii of the spoke portion 6 located on the inside of the vehicle.

[0036] In the above airless tire structure, the width dimension W of the split ring 7A varies periodically in the tire circumferential direction with a maximum Wmax at the position of the spoke portion 6, and there is a gap S between adjacent split rings 7A, 7A. Moreover, in the above airless tire structure, the width dimension W of the split ring 7A differs between the vehicle outer side and the vehicle inner side, and the width dimension Wo of the split ring 7A arranged on the vehicle outer side, which is the left side in Fig. 8, is larger than the width dimension Wi of the split ring 7A6 arranged on the vehicle inner side.

[0037] As with the previous embodiment, the above airless tire structure can improve the section modulus of the spoke portion 6 and the split ring 7A against a lateral load and effectively increase the lateral rigidity of the tire, thereby contributing to improved durability of the tire.

[0038] In the above airless tire structure, in the case where there are four rows of spoke portions 6 as shown in Fig. 8, the width dimensions I, W of the spoke portions 6 and split rings 7A of each row may be gradually reduced in the direction from the outer side to the inner side of the vehicle, or a larger or smaller relationship may be set for the width dimensions of only selected rows. The above airless tire structure is also applicable to a configuration of an intermediate ring portion 7 that is continuous in the tire width direction (see Fig. 7).

[0039] Sixth Embodiment The airless tire structure shown in Figures 9 and 10 has a basic configuration equivalent to that of the first embodiment, and is configured such that split rings 7A adjacent to each other in the tire width direction have thick ribs R at their widthwise ends.

[0040] In an airless tire structure, when adjacent split rings 7A come into contact with each other, if the dimension in the thickness direction is small, the contact is unstable and it is difficult to ensure sufficient rigidity. In contrast, in the above airless tire structure, by providing a rib R having a dimension in the thickness direction at the end in the width direction of the split ring 7A, when a lateral load of a certain level or more is applied, adjacent split rings 7A come into stable contact with each other, and it is possible to effectively improve rigidity in the tire width direction.

[0041] The configuration of the airless tire structure according to the present invention is not limited to the above-described embodiments, and may be modified as appropriate without departing from the gist of the present invention, and the configurations of the respective embodiments may be combined. [Explanation of symbols]

[0042] 3 Support structure 6 Spoke section 7 Intermediate ring section 7A Split Ring R Rib T Tire

Claims

1. The tire has a structure in which a plurality of radially arranged spoke parts and at least one intermediate ring part that is concentric with the spoke parts and is connected to each other at the middle of the spoke parts with respect to the tire center, An airless tire structure comprising a plurality of rows of spoke portions aligned in a circumferential direction in a tire width direction, and wherein the spoke portions of two adjacent rows are offset from each other in the circumferential direction.

2. 2. The airless tire structure according to claim 1, wherein when a width dimension of the spoke portion in the tire width direction is I, a width dimension of the tire is L, and a number of rows of the spoke portion in the tire width direction is N, the relationship between these is I≧L / N.

3. 2. The airless tire structure according to claim 1, wherein the intermediate ring portion is composed of a plurality of split rings divided into the same number as the number of rows of the spoke portions, and each of the split rings has one row of the spoke portions arranged therein.

4. 4. The airless tire structure according to claim 3, wherein a dimension of the split ring in the tire width direction is maximum at the position of the spoke portion and varies in the tire circumferential direction, and a gap is provided between adjacent split rings.

5. 2. The airless tire structure according to claim 1, wherein the intermediate ring portion is continuous in the tire width direction, and all rows of the spoke portions are disposed on the intermediate ring portion.

6. The width dimension of the spoke portion differs between the outer side and the inner side of the vehicle, 6. The airless tire structure according to claim 3, wherein a width dimension of the spoke portion arranged on an outer side of the vehicle is larger than a width dimension of the spoke portion arranged on an inner side of the vehicle.

7. 5. The airless tire structure according to claim 3, wherein split rings adjacent in the tire width direction are structured to come into contact with each other under a lateral load of 40% or more of a vehicle wheel load.

8. 5. The airless tire structure according to claim 3, wherein the split rings adjacent to each other in the tire width direction have thick ribs at their ends in the tire width direction.

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