JP2023015874A - airless tire - Google Patents

Abstract

To provide an airless tire capable of improving anti-uneven wear performance and maneuvering stability performance by uniformizing grounding pressure distribution when grounding on a road surface.SOLUTION: An airless tire 1 includes: a tread ring 2 having a grounding surface 2a; a hub 3 arranged on an inner side in a tire radial direction of the tread ring 2 and fixed to a wheel axle; and a spoke 4 for connecting the tread ring 2 and the hub 3. The tread ring 2 includes an outer rubber layer 6 which grounds on a road surface, an inner rubber layer 7 in contact with a spoke 4, and an intermediate rubber layer 8 arranged between the outer rubber layer 6 and the inner rubber layer 7. The intermediate rubber layer 8 includes a first rubber member 8A and a second rubber member 8B different in hardness.SELECTED DRAWING: Figure 3

Description

FIELD OF THE DISCLOSURE The present disclosure relates to airless tires capable of supporting loads by their structure without the use of high pressure air.

Conventionally, various airless tires are known in which a tread ring and a hub are connected with spokes. For example, Patent Literature 1 below proposes an airless tire including a cylindrical tread ring having a contact surface, a hub fixed to an axle, and spokes made of a polymer material.

JP 2016-130071 A

Compared to pneumatic tires, airless tires such as those disclosed in Patent Document 1 tend to have an uneven contact pressure distribution when they contact the road surface, and further improvements are desired in terms of uneven wear resistance performance and steering stability performance. was rare.

The present disclosure has been devised in view of the actual situation as described above, and aims to provide an airless tire capable of improving uneven wear resistance performance and steering stability performance by uniforming the ground contact pressure distribution when grounded on the road surface. Its main purpose.

The present disclosure is an airless tire comprising a tread ring having a ground contact surface, a hub disposed radially inside the tread ring and fixed to an axle, and connecting the tread ring and the hub. The tread ring comprises an outer rubber layer contacting the road surface, an inner rubber layer contacting the spokes, and an intermediate rubber layer disposed between the outer rubber layer and the inner rubber layer. and wherein the intermediate rubber layer includes a first rubber member and a second rubber member having different hardnesses.

In the airless tire of the present disclosure, the tread ring includes an outer rubber layer in contact with the road surface, an inner rubber layer in contact with the spokes, and an intermediate rubber layer disposed between the outer rubber layer and the inner rubber layer. , the intermediate rubber layer includes a first rubber member and a second rubber member having different hardnesses.

In such an airless tire, the hardness of the intermediate rubber layer can be adjusted based on the profile of the tire meridian cross section of the ground contact surface, so that the contact pressure can be adjusted to be uniform when the tire contacts the road surface. Therefore, the heiress tire of the present disclosure can uniformize the ground contact pressure distribution when grounded on the road surface and improve uneven wear resistance performance and steering stability performance.

1 is a perspective view showing an embodiment of an airless tire of the present disclosure; FIG. It is a side view of an airless tire. 1 is a partial cross-sectional perspective view of a tread ring and spokes; FIG. It is a tire meridian sectional view of a tread ring. It is a tire meridian cross-sectional view of a tread ring of another embodiment. It is a contact shape and a contact pressure distribution of a comparative example. It is a contact shape and a contact pressure distribution of an example.

An embodiment of the present disclosure will be described in detail below with reference to the drawings.
FIG. 1 is a perspective view showing an heiress tire 1 of this embodiment, and FIG. 2 is a side view of the heiress tire 1. As shown in FIG. As shown in FIGS. 1 and 2, the heiress tire 1 of the present embodiment includes a tread ring 2 having a ground contact surface 2a, a hub 3 arranged inside the tread ring 2 in the tire radial direction, and the tread ring 2. and spokes 4 for connecting the hub 3.

Hub 3 preferably includes a fixed portion 3a that is fixed to an axle (not shown) of the vehicle. Such an heiress tire 1 can support a load acting on the tread ring 2 by means of the hub 3 and the spokes 4 without using high pressure air. Therefore, the heiress tire 1 of the present embodiment is free from the risk of puncture.

The spokes 4 of this embodiment include a plurality of plate-like spoke plates 5 each having a width in the axial direction of the tire that is greater than a thickness in the circumferential direction of the tire. In such spokes 4, when a load acts on the tread ring 2, a tensile force acts on the spoke plates 5 positioned above the hub 3, and a compressive force acts on the spoke plates 5 positioned below the hub 3. can support the load.

3 is a partial sectional perspective view of the tread ring 2 and the spokes 4, and FIG. 4 is a tire meridian sectional view of the tread ring 2. As shown in FIG. As shown in FIGS. 3 and 4, the tread ring 2 of this embodiment includes an outer rubber layer 6 contacting the road surface, an inner rubber layer 7 contacting the spokes 4, an outer rubber layer 6 and an inner rubber layer 7. and an intermediate rubber layer 8 disposed between.

The intermediate rubber layer 8 of this embodiment includes a first rubber member 8A and a second rubber member 8B having different hardnesses. In such an heiress tire 1, the hardness of the intermediate rubber layer 8 can be adjusted based on the profile of the tire meridian cross section of the ground contact surface 2a. can be done. Therefore, the heiress tire 1 of the present embodiment can uniformize the ground contact pressure distribution when it contacts the road surface, and can improve uneven wear resistance performance and steering stability performance.

As a more preferable aspect, the first rubber member 8A and the second rubber member 8B are distributed in the intermediate rubber layer 8 in the axial direction of the tire. With such an intermediate rubber layer 8, it is easy to adjust the hardness of the intermediate rubber layer 8 based on the profile of the tire meridian cross section of the ground contact surface 2a.

The intermediate rubber layer 8 of the present embodiment includes a pair of first rubber members 8A arranged outside in the axial direction of the tire and a second rubber member 8B arranged between the first rubber members 8A. The axial width of the second rubber member 8B is preferably 20% to 50% of the width W of the tread ring 2 . Such a tread ring 2 has good balance in the tire axial direction, and can improve the steering stability performance of the heiress tire 1 .

The intermediate rubber layer 8 is not limited to such a mode, and for example, it may include a third rubber member 8C (not shown) having hardness different from that of the first rubber member 8A and the second rubber member 8B. good. In this case, the third rubber member 8C has a hardness intermediate between that of the first rubber member 8A and the second rubber member 8B, and is preferably arranged between the first rubber member 8A and the second rubber member 8B. .

Further, the intermediate rubber layer 8 includes, for example, in addition to the third rubber member 8C, more rubber members having different hardness such as a fourth rubber member, a fifth rubber member, and a sixth rubber member are used to change the hardness stepwise. may In this case, the intermediate rubber layer 8 can more finely adjust the hardness of the intermediate rubber layer 8 based on the profile of the tire meridian cross section of the ground contact surface 2a.

The tread ring 2 of this embodiment includes an outer reinforcing layer 9 arranged between the intermediate rubber layer 8 and the outer rubber layer 6, and an inner reinforcing layer arranged between the intermediate rubber layer 8 and the inner rubber layer 7. 10. Such outer reinforcing layer 9 and inner reinforcing layer 10 can increase the rigidity of the tread ring 2 and improve the uneven wear resistance performance and steering stability performance of the heiress tire 1 .

Preferably, the outer reinforcing layer 9 and the inner reinforcing layer 10 each include at least one reinforcing ply 11 having reinforcing cords disposed thereon. The reinforcing cords are made of, for example, metal cords, organic fiber cords, or the like. It is desirable that the reinforcing cords be arranged obliquely with respect to the tire circumferential direction.

The outer reinforcing layer 9 and the inner reinforcing layer 10 of this embodiment each include two reinforcing plies 11 . The two reinforcing plies 11 of the outer reinforcing layer 9 are desirably arranged so as to be inclined in opposite directions to each other with respect to the tire circumferential direction. The two reinforcing plies 11 of the inner reinforcing layer 10 are desirably arranged so as to be inclined in opposite directions to each other with respect to the tire circumferential direction.

The tread ring 2 includes sidewall rubbers 12 connecting the outer rubber layer 6 and the inner rubber layer 7 on at least one side of the intermediate rubber layer 8 in the tire axial direction, both sides in this embodiment. Such a tread ring 2 can improve the durability of the heiress tire 1 without the risk of the intermediate rubber layer 8 coming into contact with external obstacles or the like.

The tread ring 2 is formed with a plurality of circumferential grooves 13 extending in the tire circumferential direction, two in this embodiment, on a ground contact surface 2a that contacts the road surface during running. The ground plane 2a is not limited to such an aspect, and may be, for example, block-shaped, or may be formed with a plurality of recesses.

A boundary between the first rubber member 8A and the second rubber member 8B of the present embodiment is located inside the circumferential groove 13 in the tire radial direction. In such a tread ring 2, since the stress transition point due to the difference in hardness between the first rubber member 8A and the second rubber member 8B is not the contact surface 2a, the contact pressure distribution when contacting the road surface is uniform. is easy.

As shown in FIG. 4, the tread ring 2 defines, for example, a profile in the tire meridian cross-section of the ground contact patch 2a. The profile of the ground-contacting surface 2a includes a first region 2b, which is the radially outer region of the first rubber member 8A, and a second region 2c, which is the radially outer region of the second rubber member 8B. is desirable. The second region 2c of this embodiment is the region between the two circumferential grooves 13. As shown in FIG. Such a profile is suitable for making the ground contact pressure distribution uniform.

The first region 2b and the second region 2c of the present embodiment are each formed in a smooth convex curved shape. The radius of curvature R2 of the second region 2c is preferably larger than the radius of curvature R1 of the first region 2b. The radius of curvature R2 of the second region 2c is preferably twice the width W of the tread ring 2 or more. Since the curvature radius R2 of the second region 2c is at least twice the width W of the tread ring 2, it is possible to suppress excessive changes in the ground contact pressure distribution in the second region 2c, and the heiless tire 1 It is possible to improve the uneven wear resistance performance and the steering stability performance of the tire.

Here, the curvature radius R1 of the first region 2b and the curvature radius R2 of the second region 2c are the average values of the curvature radii measured at a plurality of points of the convex curves of the first region 2b and the second region 2c. . In addition, the first region 2b and the second region 2c may each be formed in a single arc shape, for example.

The hardness of the second rubber member 8B of this embodiment is smaller than the hardness of the first rubber member 8A. In such a tread ring 2, the ground contact pressure of the second region 2c protruding in the arc can be relieved by the second rubber member 8B, and the ground contact pressure distribution when grounded on the road surface can be made uniform. Uneven wear resistance performance and steering stability performance can be improved.

The hardness of the rubber member can be evaluated by Young's modulus E of the rubber member, for example. Young's modulus E2 of the second rubber member 8B of the present embodiment is smaller than Young's modulus E1 of the first rubber member 8A. The Young's modulus E2 of the second rubber member 8B is preferably 20% to 80% of the Young's modulus E1 of the first rubber member 8A.

The Young's modulus E2 of the second rubber member 8B is 20% or more of the Young's modulus E1 of the first rubber member 8A, thereby suppressing an excessive hardness difference between the first rubber member 8A and the second rubber member 8B. The ground contact pressure distribution can be made uniform when the ground contact surface 2a contacts the road surface. By setting the Young's modulus E2 of the second rubber member 8B to be 80% or less of the Young's modulus E1 of the first rubber member 8A, the effect of alleviating the contact pressure of the second region 2c can be reliably exhibited.

As shown in FIGS. 1 and 2, the hub 3 is made of a non-elastic material such as metal. The hub 3 preferably has a disk-shaped fixed portion 3 a fixed to the axle and a cylindrical portion 3 b connected to the spokes 4 . The fixing portion 3a of the hub 3 is formed with, for example, a plurality of fixing holes. The fixing portion 3a of the hub 3 is not limited to such a mode, and may be, for example, one that can be attached to a dedicated axle with one touch.

The spokes 4 are made of, for example, an elastic polymeric material. The polymeric material is desirably selected appropriately from a single elastomer, a composite elastomer of two or more kinds, an elastomer containing fibers, and the like. Such spokes 4 have an excellent balance of weight reduction, flexibility, and strength, and are useful for improving the fuel efficiency performance, ride comfort performance, and durability performance of the heiress tire 1 in a well-balanced manner.

The spokes 4 of this embodiment include a plurality of spoke plates 5 , an inner cylindrical portion 14 connected to the hub 3 and an outer cylindrical portion 15 connected to the tread ring 2 . Thereby, each spoke plate 5 is indirectly connected to the tread ring 2 and the hub 3 .

Such spokes 4 can be firmly connected to the hub 3 and the tread ring 2, and the durability performance of the heiress tire 1 can be improved. In addition, the spokes 4 may, for example, omit the inner cylindrical portion 14 and the outer cylindrical portion 15 and each of the spoke plates 5 may be directly connected to the tread ring 2 and the hub 3 .

Each of the spoke plates 5 is preferably curved in a substantially S-shape when viewed from the tire axial direction. Such spokes 4 can reduce strain when a compressive force is applied by bending deformation of the two curved portions, and can improve the durability performance of the heiress tire 1 .

The spoke plates 5 include, for example, a first spoke plate 5A arranged on one side in the tire axial direction and a second spoke plate 5B arranged on the other side in the tire axial direction when viewed from the thickness direction of the spoke plate 5. and The first spoke plates 5A and the second spoke plates 5B are arranged alternately in the tire circumferential direction, for example. Such spoke plates 5 can achieve both weight reduction and balance in the axial direction of the tire, and can achieve both low fuel consumption performance and steering stability performance of the heiress tire 1 .

Each of the spoke plates 5 preferably extends obliquely with respect to the tire axial direction. Such spokes 4 can improve the rigidity in the tire circumferential direction and improve the durability performance of the heiress tire 1 .

FIG. 5 is a tire meridional cross-sectional view of a tread ring 20 of another embodiment. The same reference numerals are given to the same components as those of the above-described embodiment, and the description thereof is omitted. As shown in FIG. 5, the profile of the ground-contacting surface 20a of this embodiment consists of a first region 20b, which is the outer region of the first rubber member 8A in the tire radial direction, and a radially outer region of the second rubber member 8B. 2nd area|region 20c which is an outer area|region.

The profile of the ground plane 20a in this embodiment is arcuate in the first region 20b and straight in the second region 20c. The hardness of the second rubber member 8B of this embodiment is greater than the hardness of the first rubber member 8A. Such a tread ring 20 can reduce the contact pressure of the first region 20b, which is higher than that of the second region 20c, by the first rubber member 8A.

The Young's modulus E1 of the first rubber member 8A of this embodiment is smaller than the Young's modulus E2 of the second rubber member 8B. The Young's modulus E1 of the first rubber member 8A is preferably 20% to 80% of the Young's modulus E2 of the second rubber member 8B.

The Young's modulus E1 of the first rubber member 8A is 20% or more of the Young's modulus E2 of the second rubber member 8B, thereby suppressing an excessive difference in hardness between the first rubber member 8A and the second rubber member 8B. The ground contact pressure distribution can be made uniform when the ground contact surface 2a contacts the road surface. By setting the Young's modulus E1 of the first rubber member 8A to be 80% or less of the Young's modulus E2 of the second rubber member 8B, the effect of alleviating the contact pressure of the first region 2b can be reliably exhibited.

Although the particularly preferred embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the above-described embodiments, and can be implemented in various modifications.

Airless tires of comparative examples and examples having the basic structure shown in FIGS. 1 to 4 were produced as prototypes, and the contact shape and contact pressure distribution were tested when the experimentally produced airless tires were in contact with the road surface. Main common specifications, specifications of comparative examples, specifications of examples, and test methods are as follows.

<Common specifications>
Tread ring width: 145mm
Hub outer diameter: 14 inches Curvature radius of the second area: 350mm

<Comparative example specifications>
Young's modulus of the second rubber member/Young's modulus of the first rubber member: 100%

<Specifications of Example>
Young's modulus of second rubber member/Young's modulus of first rubber member: 50%

The results of the tests are shown in FIGS. 6 and 7. FIG. FIG. 6 shows the ground shape and ground pressure distribution of a comparative example, and FIG. 7 shows the ground shape and ground pressure distribution of an example.

As a result of the test, the airless tire of the example had a larger contact shape when contacting the road surface, a more uniform contact pressure distribution, and improved uneven wear resistance and steering stability performance compared to the comparative example. It was confirmed that

[Appendix]
The present disclosure includes the following aspects.

The present disclosure (1) is an airless tire comprising a tread ring having a ground contact surface, a hub arranged inside the tread ring in the tire radial direction and fixed to an axle, and the tread ring and the hub. The tread ring comprises an outer rubber layer contacting the road surface, an inner rubber layer contacting the spokes, and an intermediate rubber disposed between the outer rubber layer and the inner rubber layer. and the intermediate rubber layer includes a first rubber member and a second rubber member having different hardnesses.

The present disclosure (2) is the heiress tire according to the present disclosure (1), wherein the first rubber member and the second rubber member are distributed in the tire axial direction of the intermediate rubber layer.

In the present disclosure (3), the tread ring includes an outer reinforcing layer disposed between the intermediate rubber layer and the outer rubber layer, and an inner reinforcing layer disposed between the intermediate rubber layer and the inner rubber layer. The heiress tire according to (1) or (2) of the present disclosure, including a reinforcing layer.

The present disclosure (4) is the heiress tire according to the present disclosure (3), wherein the outer reinforcing layer and the inner reinforcing layer each include at least one reinforcing ply having reinforcing cords arranged thereon.

The present disclosure (5) is the heiress tire according to the present disclosure (4), wherein the outer reinforcing layer and the inner reinforcing layer each include two reinforcing plies.

The present disclosure (6) is the present disclosure (1), wherein the tread ring includes sidewall rubber connecting the outer rubber layer and the inner rubber layer on at least one side of the intermediate rubber layer in the tire axial direction. The heiress tire according to any one of (5).

In the present disclosure (7), the intermediate rubber layer includes a pair of the first rubber members arranged outside in the axial direction of the tire, and the second rubber member arranged between the first rubber members. , the heiress tire according to any one of the present disclosure (1) to (6).

In the present disclosure (8), the profile of the tire meridian cross section of the ground contact surface of the tread ring is formed in a convex curved shape in the outer region in the tire radial direction of the second rubber member, and the hardness of the second rubber member is is the heiress tire according to (7) of the present disclosure, having a hardness lower than that of the first rubber member.

In the present disclosure (9), the profile of the tire meridian cross-section of the ground contact surface of the tread ring is formed linearly in the outer region in the tire radial direction of the second rubber member, and the hardness of the second rubber member is , the heiress tire according to (7) of the present disclosure, wherein the hardness is greater than that of the first rubber member.

REFERENCE SIGNS LIST 1 airless tire 2 tread ring 2a tread 3 hub 4 spoke 6 outer rubber layer 7 inner rubber layer 8 intermediate rubber layer 8A first rubber member 8B second rubber member

Claims (9)

It is an airless tire,
A tread ring having a ground contact surface, a hub arranged inside the tread ring in the tire radial direction and fixed to an axle, and spokes for connecting the tread ring and the hub,
The tread ring includes an outer rubber layer in contact with the road surface, an inner rubber layer in contact with the spokes, and an intermediate rubber layer disposed between the outer rubber layer and the inner rubber layer,
The intermediate rubber layer includes a first rubber member and a second rubber member having different hardnesses,
airless tires. The heiress tire according to claim 1, wherein the first rubber member and the second rubber member are distributed in the tire axial direction of the intermediate rubber layer. The tread ring includes an outer reinforcing layer arranged between the intermediate rubber layer and the outer rubber layer, and an inner reinforcing layer arranged between the intermediate rubber layer and the inner rubber layer. 3. The heiress tire according to Item 1 or 2. The heiress tire according to claim 3, wherein the outer reinforcing layer and the inner reinforcing layer each include at least one reinforcing ply having reinforcing cords arranged thereon. The heiress tire according to claim 4, wherein the outer reinforcing layer and the inner reinforcing layer each include two reinforcing plies. 6. The tread ring according to any one of claims 1 to 5, wherein the tread ring includes sidewall rubber connecting the outer rubber layer and the inner rubber layer on at least one side of the intermediate rubber layer in the tire axial direction. airless tires. The intermediate rubber layer of any one of claims 1 to 6, wherein the intermediate rubber layer includes a pair of the first rubber members arranged outside in the axial direction of the tire, and the second rubber member arranged between the first rubber members. The heiress tire according to any one of the items. A profile of the ground contact surface of the tread ring in a tire meridian cross section is formed in a convex curved shape in an outer region of the second rubber member in the tire radial direction,
The heiress tire according to claim 7, wherein hardness of said second rubber member is lower than hardness of said first rubber member. A profile of the tire meridian cross section of the ground contact surface of the tread ring is formed linearly in an outer region of the second rubber member in the tire radial direction,
The heiress tire according to claim 7, wherein hardness of said second rubber member is higher than hardness of said first rubber member.

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