JP2023008258A - Run flat tire - Google Patents

Abstract

To provide a run flat tire capable of facilitating rim assembly and suppress an increase in rolling resistance.SOLUTION: A run flat tire 10 comprises: a tire body 12 having a left and right pair of bead parts 20 in which a bead core 18 is embedded, a side wall part 22 extending outward in a tire radial direction from each of the bead parts 20, and a tread part 24 continuous to the side wall part 22; a core 14 which is provided inside the tire radial direction of the tread part 24 in the tire body 12 and between the pair of bead parts 20, is an annular hollow body in a tire circumferential direction in a state in which an inner pressure is applied thereto, and has a flexibility in a state in which the inner pressure is reduced; and a holding member 16 for holding the core 14 in a state in which the core is separated from a tire inner surface 12A of the tire body 12.SELECTED DRAWING: Figure 1

Description

The present invention relates to runflat tires.

A tire having three tire air chambers is disclosed (see Patent Document 1). Even if some of the tire chambers are punctured, the rest of the tire chambers that are not punctured support the load, allowing the vehicle to run.

JP 2007-106259 A

However, in the above-described conventional example, since the inner bead portion is provided in addition to the outer bead portion corresponding to the bead portion of a general one-chamber tire, it is difficult to assemble the rim. In addition, there are problems that the partition wall deforms every time the tire rolls, which increases the rolling resistance.

SUMMARY OF THE INVENTION An object of the present invention is to facilitate rim assembly and to suppress an increase in rolling resistance in a run-flat tire.

A run-flat tire according to a first aspect includes a pair of left and right bead portions in which bead cores are embedded, sidewall portions extending radially outward from the bead portions, and a tread portion connected to the sidewall portions. and a tire body provided inside the tread portion of the tire body in the tire radial direction and between the pair of bead portions, and becomes an annular hollow body in the tire circumferential direction in a state in which internal pressure is applied, and the internal pressure is reduced. and a flexible core, and a holding member that holds the core away from the tire inner surface of the tire body.

In this run-flat tire, a core is provided radially inside the tread portion of the tire body and between a pair of bead portions, that is, in a hollow portion within the tire. Since the core has flexibility when the internal pressure is reduced, it becomes easier to load the core inside the tire. In addition, since the core is easily deformed during rim assembly, the presence of the core does not interfere with rim assembly. This core becomes an annular hollow body in the tire circumferential direction in a state in which internal pressure is applied. Further, the core is held in a state separated from the tire inner surface of the tire body by the holding member. Therefore, during normal running when the tire body is filled with normal internal pressure, the core does not deform due to contact with the tire inner surface of the tread portion or the tire inner surface of the bead portion. Therefore, an increase in rolling resistance is suppressed.

When the internal pressure of the tire body is lost due to a puncture, a core is interposed between the tread portion and the rim, and the core supports the load acting on the tire, enabling safe run-flat driving. It is possible.

A second aspect is the run-flat tire according to the first aspect, wherein the holding member is a string.

In this run-flat tire, since the holding member is a string, it is possible to hold the core with a simple and lightweight member.

A third aspect is the run-flat tire according to the first aspect or the second aspect, wherein a plurality of cores are provided side by side in the tire width direction.

In this run-flat tire, since a plurality of run-flat tire cores are arranged side by side in the tire width direction, a long nail or the like penetrates the tire body and penetrates a part of the cores, and the internal pressure of the cores is increased. Even if it drops, it is possible to support the load acting on the tire with other cores. Thereby, the cut of the sidewall portion can be suppressed.

A fourth aspect is the run-flat tire according to claim 3, wherein in the run-flat tire according to the third aspect, the adjacent cores are joined together.

In this run-flat tire, since adjacent run-flat tire cores are joined together, random movement of the cores during normal running can be suppressed. Also, during run-flat running, the support state of the tire load by the core can be stabilized.

A fifth aspect is the run-flat tire according to any one of the first to fourth aspects, wherein the internal pressure of the core is set higher than the internal pressure of the tire body.

In this run-flat tire, since the internal pressure of the core is set higher than the internal pressure of the tire body, the shape of the core can be easily maintained. Also, if the pressure difference between the internal pressure of the tire body and the internal pressure of the core is small, the decrease in the internal pressure of the core is very small. Therefore, regarding the management of the tire internal pressure, there is no need to manage anything other than the internal pressure of the tire body. Since the internal pressure of the tire body is managed in the same manner as the normal tire internal pressure, the internal pressure can be easily managed.

ADVANTAGE OF THE INVENTION According to this invention, it is a run-flat tire.

It is a half cross-sectional view showing a state in which the run-flat tire according to the present embodiment is cut along the tire axial direction. (A) is a half cross-sectional view showing the state of a run-flat tire during normal running. (B) is a half cross-sectional view showing the state of the run-flat tire during run-flat running. It is a half cross-sectional view showing a state in which a run-flat tire according to a modification is cut along the tire axial direction.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the present invention will be described based on the drawings. Components shown using the same reference numerals in each drawing mean the same or similar components. It should be noted that redundant descriptions and reference numerals in the embodiments described below may be omitted. Also, the drawings used in the following description are all schematic, and the dimensional relationship of each element, the ratio of each element, etc. shown in the drawings do not necessarily match the actual ones. Moreover, the dimensional relationship of each element, the ratio of each element, etc. do not necessarily match between a plurality of drawings.

In the drawings, the arrow R direction indicates the tire radial direction, and the arrow W direction indicates the tire width direction. A tire radial direction means a direction orthogonal to a tire rotation axis (not shown). The tire width direction means a direction (arrow X direction) parallel to the tire rotation axis. The tire width direction can also be called the tire axial direction.

In FIG. 1 , a run-flat tire 10 according to this embodiment has a tire body 12 , a core 14 and a holding member 16 .

The tire main body 12 includes a pair of left and right bead portions 20 in which the bead cores 18 are embedded, sidewall portions 22 extending radially outward from the bead portions 20, and a tread portion 24 connected to the sidewall portions 22. .

The bead portion 20 is a portion that fits into the rim 26 . The tire body 12 further comprises a carcass 28 . The carcass 28 has a carcass main body portion 28A that straddles the pair of left and right bead portions 20, and a folded portion 28B that folds around the bead core 18 from the inside to the outside in the tire width direction. A belt 30 is provided outside the carcass body portion 28A in the tire radial direction.

The tread portion 24 is a contact portion and is provided outside the belt 30 in the tire radial direction. For example, four circumferential main grooves 24A are formed in the tread portion 24 . A central rib 24B is defined by two circumferential main grooves 24A close to the tire equatorial plane CL. A central land portion 24C is defined by two circumferential main grooves 24A on both sides of the tire equatorial plane CL. A shoulder portion 24D is provided outside the outermost circumferential main groove 24A in the tire width direction.

The core 14 is provided inside the tread portion 24 of the tire body 12 in the tire radial direction and between the pair of bead portions 20, and becomes an annular (for example, toroidal) hollow body in the tire circumferential direction when internal pressure is applied. a support. The core 14 has flexibility when the internal pressure is reduced. Moreover, it is desirable that the core 14 is difficult to expand when the internal pressure is applied. For this reason, as the material for the core 14, a rubber film reinforced with cords made of organic fibers or metal fibers having low stretchability, for example, similar to the ply of a tire, is used.

In this embodiment, a plurality of cores 14, for example, three cores 14 are provided side by side in the tire width direction. The number of cores 14 is at least two, preferably three. If there are two cores 14, the structure is simple, but it becomes difficult for the remaining one core 14 to support the load when the internal pressure of one core 14 is lost. In addition, when the number of cores 14 is four or more, it takes time and effort to fill each core 14 with internal pressure, and the dimension of each core 14 in the tire radial direction becomes small, making it difficult to satisfy performance as a core. .

Adjacent cores 14 are coupled to each other, for example. Any means such as adhesion, welding, and fastening can be used as the connecting means. The dimensions of each core 14 are, for example, the same as each other, but the dimensions may differ depending on the location. The dimension of the core 14 in the tire width direction when the internal pressure is applied is determined in consideration of the allowable amount of approach between the tread portion 24 and the rim 26 and the allowable amount of deformation of the sidewall portion 22 so as to enable run-flat running. set.

As an example, the central core 14 of the three cores 14 is arranged at a position covering from the central rib 24B to part of the central land portion 24C. Further, the cores 14 on both sides of the core 14 are arranged at positions covering from the central land portion 24C to the shoulder portions 24D.

The cross-sectional shape of the core 14 in the tire axial direction cross section is circular, for example. If no reinforcing member is used to constrain the cross-sectional shape, the cross-sectional shape naturally becomes circular, which simplifies the configuration. Other cross-sectional shapes of the core 14 may be achieved using some type of stiffening member.

3, the interior of one flat core 14 may be partitioned into, for example, three air chambers 34, 36, 38 by partition walls 32. As shown in FIG.

In FIG. 1 , the holding member 16 holds each core 14 apart from the tire inner surface 12A of the tire body 12 . The holding member 16 is, for example, a string and has flexibility. The holding members 16 are provided at a plurality of locations, for example, four or more locations in the tire circumferential direction for one core 14 . The holding member 16 extends outward in the tire radial direction from, for example, the outermost portion of the core 14 in the tire radial direction, and is coupled to the tire inner surface 12</b>A on the inner side of the tread portion 24 . The holding member 16 and the tire inner surface 12A are joined by any means such as adhesion or embedding during vulcanization of the tire. The holding member 16 and the core 14 are also connected by any means. In the example shown in FIG. 3, the holding members 16 are provided at, for example, two partition walls 32 in the tire width direction.

After the run-flat tire 10 is attached to the rim 26, the tire body 12 is filled with internal pressure. At this time, the internal pressure of the core 14 may be set higher than the internal pressure of the tire body 12 . In addition, the internal pressure filling to the tire main body 12 can be performed like a general tire. The internal pressure filling of the core 14 may be performed before rim assembly, or may be performed from a dedicated filling port (not shown) after rim assembly.

(Action)
This embodiment is configured as described above, and the operation thereof will be described below. In FIGS. 2A and 2B, in the run-flat tire 10 according to the present embodiment, the tread portion 24 of the tire body 12 is located radially inside the tread portion 24 and between the pair of bead portions 20, that is, in the hollow portion of the tire. A child 14 is provided. Since the core 14 has flexibility when the internal pressure is reduced, it becomes easier to load the core 14 inside the tire. Moreover, since the core 14 is easily deformed during rim assembly for assembling the run-flat tire 10 to the rim 26, the presence of the core 14 does not hinder the rim assembly.

This core 14 becomes an annular hollow body in the tire circumferential direction in a state in which internal pressure is applied. Further, the core 14 is held in a state separated from the tire inner surface of the tire body 12 by the holding member 16 . Therefore, as shown in FIG. 2A, during normal running with the tire main body 12 filled with normal internal pressure, the core 14 comes into contact with the tire inner surface of the tread portion 24 and the tire inner surface of the bead portion 20. Child 14 is not deformed. Therefore, an increase in rolling resistance is suppressed.

As shown in FIG. 2(B), when the internal pressure of the tire body 12 is lost due to puncture, the core 14 is interposed between the tread portion 24 and the rim, and the core 14 acts on the tire. By supporting the , it is possible to safely run-flat.

If the holding member 16 is a string, the core 14 can be held with a simple and lightweight member.

When a plurality of cores 14 are arranged side by side in the tire width direction, a long nail or the like (not shown) penetrates the tire body 12 and penetrates a part of the cores 14, and the internal pressure of the cores 14 increases. Even if it drops, it is possible for other cores 14 to support the load acting on the tire. As a result, the deflection of the sidewall portion 22 increases, and the sidewall portion 22 is prevented from being cut by being sandwiched between the road surface and the rim flange.

When the adjacent cores 14 are connected to each other, random movement of the cores 14 during normal running can be suppressed. Further, during run-flat running, the support state of the tire load by the core 14 can be stabilized.

When the internal pressure of the core 14 is set higher than the internal pressure of the tire body 12, the shape of the core can be easily maintained. Also, if the pressure difference between the internal pressure of the tire body and the internal pressure of the core is small, the decrease in the internal pressure of the core is very small. Therefore, regarding the management of the tire internal pressure, there is no need to manage anything other than the internal pressure of the tire body 12 . Since the internal pressure management of the tire body 12 is the same as that of a normal tire internal pressure, the internal pressure management is easy.

Thus, according to the present embodiment, it is possible to facilitate rim assembly and suppress an increase in rolling resistance in a run-flat tire.

[Other embodiments]
An example of the embodiment of the present invention has been described above, but the embodiment of the present invention is not limited to the above, and can be modified in various ways without departing from the spirit of the present invention. Of course there is.

Although a string is given as an example of the holding member 16, the holding member 16 is not limited to a string, and may be a member such as a wire, a membrane, or a net.

Although the internal pressure of the core 14 is set higher than the internal pressure of the tire body 12 , the internal pressure of the tire body 12 may be equal to or higher than the internal pressure of the core 14 .

DESCRIPTION OF SYMBOLS 10... Run-flat tire, 12... Tire main body, 12A... Tire inner surface, 14... Core, 16... Holding member, 18... Bead core, 20... Bead part, 22... Side wall part, 24... Tread part

Claims (5)

a tire body comprising a pair of left and right bead portions in which bead cores are embedded, sidewall portions extending radially outward from the bead portions, and a tread portion connected to the sidewall portions;
Provided between the pair of bead portions and inside the tread portion in the tire body in the tire radial direction, it becomes an annular hollow body in the tire circumferential direction when internal pressure is applied, and becomes flexible when the internal pressure is reduced. a core having
a holding member that holds the core away from the tire inner surface of the tire body;
A run-flat tire with A run-flat tire according to claim 1, wherein said retaining member is a string. The run-flat tire according to claim 1 or 2, wherein a plurality of said cores are provided side by side in the tire width direction. 4. The run-flat tire according to claim 3, wherein said cores adjacent to each other are joined together. The run-flat tire according to any one of claims 1 to 4, wherein the internal pressure of the core is set higher than the internal pressure of the tire body.

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