Run-flat tire

Abstract

To provide a run-flat tire of a side-reinforcement type capable of simultaneously achieving run-flat traveling performance and normal-time riding comfort at a high dimension.SOLUTION: This run-flat tire comprises side-reinforcement rubber crescent-shaped in section in a wide wall part. In an unloaded state, at least a part of the side-reinforcement rubber is composed of a plurality of columnar blocks. The adjacent blocks are connected to each other. A cavity is formed between the adjacent blocks. When the inner pressure of the tire drops below a prescribed inner pressure during rim assembling, the columnar blocks rotate around the extending direction of the blocks, causing reduction of the area of the cavity compared with that in the unloaded state in a plan view in a tire width direction. Thus, the adjacent blocks are tightly bonded to each other.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a run-flat tire, and more particularly to a side-reinforced run-flat tire having a side-reinforcement rubber on the sidewall portion. [Background technology]

[0002] A side-reinforced run-flat tire with a crescent-shaped side-reinforcement rubber on the sidewall is known as a tire that can be driven even in the event of an abnormality such as a puncture (for example, Patent Document 1). With such a tire, for example, in the event of a puncture, the side-reinforcement rubber takes over the load and supports it, allowing the tire to be driven for a certain distance.

[0003] In such a side-reinforced run-flat tire, the elastic modulus of the sidewall of the tire increases due to the placement of the side-reinforcement rubber, and the vertical spring constant increases, which becomes a factor in deteriorating the ride comfort during normal use. In this way, there is usually a trade-off between run-flat driving performance and ride comfort under normal conditions.

[0004] In particular, when tires become larger, the height of the sidewall increases, and at the same time, the vehicle generally becomes larger, so the load also increases. Therefore, the side reinforcing rubber becomes thicker to support the larger load, and the above-mentioned trade-off tendency becomes stronger. Due to such factors, trying to avoid a deterioration in ride comfort can be an obstacle to the realization of larger run-flat tires. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2023-89362 A Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a run-flat tire which achieves both high levels of run-flat driving performance and high levels of ride comfort under normal conditions. [Means for solving the problem]

[0007] The gist and configuration of the present invention are as follows. (1) A run-flat tire having a side reinforcing rubber with a crescent-shaped cross section on the sidewall portion, In a no-load state, at least a part of the side reinforcing rubber is composed of a plurality of columnar blocks, adjacent blocks are connected to each other, and a gap is formed between the adjacent blocks, This is a run-flat tire characterized in that, when the internal pressure of the tire drops below a specified internal pressure when assembled onto a rim, the columnar blocks rotate about the extension direction of the blocks, thereby reducing the area of ​​the gap portions in a plan view seen from the tire width direction compared to the no-load state, thereby bringing adjacent blocks into close contact with each other.

[0008] (2) The run-flat tire according to (1), wherein at least some of the blocks are prismatic.

[0009] (3) The run-flat tire according to (2), wherein at least some of the blocks are square in plan view in the tire width direction.

[0010] (4) The run-flat tire according to any one of (1) to (3), wherein the blocks are arranged in a staggered manner in a plan view seen in the tire width direction.

[0011] (5) The blocks are arranged in a staggered manner in a plan view seen from the tire width direction, Adjacent blocks are connected to each other at corners of the blocks, The run-flat tire according to any one of (1) to (4), wherein at least a part of the void portions has a square shape in a plan view seen from the tire width direction.

[0012] (6) In the unloaded state, The run-flat tire according to (5) above, wherein the sides of the blocks are inclined at an inclination angle of 1° or more with respect to the tire radial direction in a plan view seen from the tire width direction.

[0013] (7) A run-flat tire as described in any one of (1) to (6), wherein, when assembled to a rim, as the internal pressure of the tire decreases from a specified internal pressure, the columnar blocks rotate about the extension direction of the blocks, so that the area of ​​the gap portions in a plan view seen from the tire width direction gradually decreases compared to the no-load state, and adjacent blocks are brought closer to each other. Effect of the Invention

[0014] According to the present invention, it is possible to provide a run-flat tire which achieves both high levels of run-flat driving performance and high levels of ride comfort under normal conditions. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing a run-flat tire having a side reinforcing rubber on a sidewall portion. [Diagram 2] FIG. 2 is a perspective view of a side reinforcing rubber of a run-flat tire according to one embodiment of the present invention. [Diagram 3] 4 is a diagram showing a part of a side reinforcing rubber in a plan view seen from the tire width direction when no load is applied; FIG. [Figure 4] FIG. 13 illustrates the filling pattern in a structure under load. [Diagram 5] 1 is a diagram showing a part of a side reinforcing rubber in a plan view seen in the tire width direction when the internal pressure of the tire drops below a specified internal pressure when assembled to a rim. FIG. [Figure 6] FIG. 1 shows the results of Example 1. [Figure 7] FIG. 1 shows the results of Example 2. [Figure 8] FIG. 1 shows the results of Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0017] Fig. 1 is a diagram showing a run-flat tire having a side reinforcing rubber on a sidewall portion. As shown in Fig. 1, a run-flat tire 1 according to an embodiment of the present invention has a side reinforcing rubber 2 having a crescent-shaped cross section on the sidewall portion.

[0018] The tire structure of the run-flat tire 1 can be a commonly used configuration except for the side reinforcing rubber 2, so detailed explanation will be omitted, but as an example, the tire can include a tread portion, a pair of sidewall portions connected to both sides of the tread portion, bead portions connected to each sidewall portion, side reinforcing rubber 2 having a crescent cross-section arranged on the sidewall portion, a carcass spanning in a toroidal shape between the pair of bead portions, and a belt arranged on the radially outer side of the crown portion of the carcass.

[0019] Fig. 2 is a perspective view of a side reinforcing rubber of a run-flat tire according to one embodiment of the present invention. Fig. 2 shows the state under no load. As shown in Fig. 2, in this embodiment, at least a part of the side reinforcing rubber 2 (preferably 80% or more of the radially extending region of the tire, and more preferably the entirety) is composed of a plurality of columnar blocks 3. In the illustrated example, each block 3 extends in the tire width direction (the height direction of the columnar block 3 is the tire width direction, and is the thickness direction in the tire width direction of the side reinforcing rubber 2 in the tire width direction cross section).

[0020] Fig. 3 is a diagram showing a part of the side reinforcing rubber in a plan view seen from the tire width direction (from the tire inner side) when no load is applied. As shown in Figs. 2 and 3, in this example, at least some of the blocks 3 (all of them in the illustrated example) are prismatic. At least some of the blocks 3 are quadrangular prism-shaped. Alternatively, the blocks 3 may be cylindrical. The bottom and top surfaces of the blocks 3 are curved in a manner corresponding to the outer and inner arcs in the tire width direction of the crescent shape of the side reinforcing rubber 2 in a cross section seen in the tire width direction. 2 and 3, in this example, at least some of the blocks 3 are square in plan view from the tire width direction. Other blocks 3 are square in shape, defined by the sides of a crescent-shaped cross section. Meanwhile, each block 3 can have various shapes, such as a rectangular shape other than a square, other polygonal shapes, a circular shape, an elliptical shape, etc., in plan view from the tire width direction.

[0021] As described above, the side reinforcing rubber 2 has a crescent-shaped cross section, and the thickness gradually decreases from the tire radial direction position where the thickness in the tire width direction is maximum toward the tire radial inside and outside. Since the length in the extension direction of each block 3 (the height of the columnar block 3) corresponds to the tire width direction thickness of the side reinforcing rubber 2 in the tire width direction cross section, the length in the extension direction of each block 3 (the height of the columnar block 3) gradually decreases from the tire radial direction position where the height is maximum (the position corresponding to the tire radial direction position where the thickness in the tire width direction is maximum) toward the tire radial inside and outside.

[0022] In the illustrated example, the multiple blocks 3 are arranged in a staggered manner in a plan view seen from the tire width direction. That is, an odd-numbered row of multiple blocks 3 and an even-numbered row of multiple blocks 3 adjacent to the odd-numbered row are arranged out of phase with each other (exactly half a pitch in the illustrated example).

[0023] 2 and 3, adjacent blocks 3 are connected to each other. In the illustrated example, adjacent blocks 3 are connected to each other at corners of the blocks 3. Furthermore, gaps 4 are formed between adjacent blocks 3. At least some of the gaps 4 are square in plan view seen from the tire width direction. On the other hand, as long as adjacent blocks 3 are connected to each other and gaps 4 are formed between the adjacent blocks 3, the arrangement of the multiple blocks 3 is not limited to the staggered arrangement described above, and the connection points between adjacent blocks 3 are not limited to corners (even if there are corners, they are not limited to corners, and there may be no corners, such as a circular shape when viewed in a planar view), and the shape of the gaps 4 when viewed in a planar view is not limited to a square, and can be various shapes.

[0024] Figure 4 shows the filling pattern when a load is applied to a structure. As shown in Figure 4, when a load is applied from a state (a) in which gaps 4 are defined by blocks 3, each block 3 rotates (approaching each other around the corners connecting adjacent blocks 3) and the area of ​​gaps 4 gradually decreases, and the blocks 3 come into close contact with each other and support each other ((b)-(d)).

[0025] FIG. 5 is a diagram showing a part of a side reinforcing rubber in a plan view seen in the tire width direction when the internal pressure of the tire drops below a specified internal pressure when assembled to a rim. In tire 1 of this embodiment, when the internal pressure of the tire decreases from the state shown in Figure 3 at the specified internal pressure, the columnar blocks 3 rotate around the extension direction of the blocks 3, and the area of ​​the void portions 4 in a plan view seen from the tire width direction decreases compared to the no-load state (compared to Figure 3), so that adjacent blocks 3 are configured to be in close contact with each other (see Figure 5). More specifically, as the internal pressure of the tire 1 decreases from the specified internal pressure, the columnar blocks 3 rotate around the extension direction of the blocks 3, so that the area of ​​the gap portions 4 in a plan view seen from the tire width direction gradually decreases compared to the no-load state, and adjacent blocks 3 are configured to be closer to each other (see states (a) to (d) in Figure 4 and Figure 5). As a result, when the internal pressure of the tire 1 drops, the blocks 3 come into close contact with each other and support each other, providing the rigidity necessary to support the load of the tire 1. According to the run-flat tire 1 of this embodiment, during normal driving, the side reinforcing rubber 2 has a configuration with multiple voids 4, so that the vertical spring is small and deterioration of ride comfort can be suppressed. Also, during run-flat driving, as described above, the adjacent blocks 3 are in close contact with each other and support each other, increasing rigidity, so that the tire load can be shouldered and supported. Thus, the run-flat tire 1 of this embodiment can achieve both run-flat driving performance and normal ride comfort at a high level.

[0026] Here, in a no-load state, it is preferable that the sides of the blocks 3 are inclined at an inclination angle of 1° or more with respect to the tire radial direction in a plan view seen from the tire width direction. This is because the direction in which the blocks 3 rotate in response to a radial load is determined, and the above-mentioned effects can be obtained more reliably.

[0027] Here, in a no-load state, the sides of the blocks 3 are preferably inclined at an angle of 40° to 50° with respect to the tire radial direction in a plan view seen from the tire width direction, and most preferably at an angle of 45° with respect to the tire width direction as shown in Fig. 3. This is because, when the internal pressure is reduced, rubbing between the blocks 3 can be suppressed by having the sides of the blocks 3 align with the tire width direction and radial direction.

[0028] Examples of the present invention will be described below, but the present invention is not limited to the following examples in any way. EXAMPLES

[0029] Example 1 A model simulating a part of a tire was created using a 3D printer, and the vertical spring was measured. Invention Example 1 was composed of multiple columnar blocks, with adjacent blocks connected to each other, and a gap was formed between the adjacent blocks. When the internal pressure of the tire drops from the specified internal pressure when assembled to a rim, the columnar blocks rotate around the extension direction of the blocks, reducing the area of ​​the gap in a plan view from the tire width direction compared to the no-load state, and as a result, the adjacent blocks are configured to be in close contact with each other. Comparative Example 1 is a case in which there is no side reinforcing rubber. As shown in FIG. 6, in Example 1, when the radial displacement was small, the vertical spring was close to that of Comparative Example 1, but when the radial displacement was large, the vertical spring increased.

[0030] Example 2 Side reinforcement rubber made by a 3D printer was attached to a quarter of the circumference of an actual tire, and the vertical spring was measured during normal use and when the tire was run-flat. Invention Example 2 was composed of multiple columnar blocks, with adjacent blocks connected to each other and gaps formed between adjacent blocks, and when the internal pressure of the tire drops from the specified internal pressure when assembled to a rim, the columnar blocks rotate around the extension direction of the blocks, reducing the area of ​​the gaps in a plan view seen from the tire width direction compared to the no-load state, thereby causing adjacent blocks to come into close contact with each other. Comparative Example 2 was a case in which the side reinforcement rubber was not included. As shown in Figures 7 and 8, the vertical springs are less affected during normal use (Figure 8), but support the load during run-flat (Figure 7).

[0031] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)] The SDGs have been proposed to realize a sustainable society. One embodiment of the present invention is thought to be a technology that can contribute to "No. 12 Responsible Consumption and Production". [Explanation of symbols]

[0032] 1: Run-flat tires, 2: Side reinforcement rubber, 3: Block, 4:Void part

Claims

1. A run-flat tire having a side reinforcing rubber having a crescent-shaped cross section on a sidewall portion, In a no-load state, at least a part of the side reinforcing rubber is composed of a plurality of columnar blocks, adjacent blocks are connected to each other, and a gap is formed between the adjacent blocks, This is a run-flat tire characterized in that, when the internal pressure of the tire drops below a specified internal pressure when assembled onto a rim, the columnar blocks rotate about the extension direction of the blocks, thereby reducing the area of ​​the gap portions in a plan view seen from the tire width direction compared to the no-load state, thereby bringing adjacent blocks into close contact with each other.

2. The run-flat tire according to claim 1 , wherein at least some of the plurality of blocks are prismatic.

3. The run-flat tire according to claim 2 , wherein at least some of the plurality of blocks are square in plan view seen in the tire width direction.

4. 3. The run-flat tire according to claim 1, wherein the blocks are arranged in a staggered manner in a plan view seen in the tire width direction.

5. The plurality of blocks are arranged in a staggered manner in a plan view seen from the tire width direction, Adjacent blocks are connected to each other at corners of the blocks, The run-flat tire according to claim 3 , wherein at least a portion of the void portion has a square shape in a plan view seen in the tire width direction.

6. In the unloaded state, 6. The run-flat tire according to claim 5, wherein the sides of the blocks are inclined at an inclination angle of 1° or more with respect to the tire radial direction in a plan view seen from the tire width direction.

7. 3. The run-flat tire according to claim 1, wherein as the internal pressure of the tire decreases from a specified internal pressure when assembled to a rim, the columnar blocks rotate around the extension direction of the blocks, so that the area of ​​the gap portions in a plan view seen from the tire width direction gradually decreases compared to the no-load state, and adjacent blocks are brought closer together.

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