阅读说明：本技术 充气轮胎 (Pneumatic tire ) 是由 长谷川圭一 曽根直幸 于 2018-06-07 设计创作，主要内容包括：本发明的充气轮胎包括由被包覆树脂包覆的线材构成的树脂包覆带束,在所述树脂包覆带束的轮胎径向内侧设有与所述树脂包覆带束的轮胎宽度方向外侧端接触的底环,所述底环的轮胎宽度方向内侧端位于比所述树脂包覆带束的轮胎宽度方向外侧端靠轮胎宽度方向内侧的位置,并且所述底环的轮胎宽度方向外侧端位于比所述树脂包覆带束的轮胎宽度方向外侧端靠轮胎宽度方向外侧的位置,所述底环在该底环的比所述树脂包覆带束的轮胎宽度方向外侧端靠轮胎宽度方向内侧的部分具有刚度减小部,该刚度减小部的刚度从轮胎宽度方向外侧朝向轮胎宽度方向内侧减小。(The pneumatic tire of the present invention includes a resin coated belt made of a wire material coated with a coating resin, a bottom ring that is provided on the inner side in the tire radial direction of the resin coated belt and contacts the outer end in the tire width direction of the resin coated belt, the inner end in the tire width direction of the bottom ring being located on the inner side in the tire width direction than the outer end in the tire width direction of the resin coated belt, and the outer end in the tire width direction of the bottom ring being located on the outer side in the tire width direction than the outer end in the tire width direction of the resin coated belt, the bottom ring having a rigidity reducing portion whose rigidity is reduced from the outer side in the tire width direction toward the inner side in the tire width direction in a portion of the bottom ring on the inner side in the tire width direction than the outer end in the tire width direction of the resin coated belt.)

1. A pneumatic tire comprising a resin-coated belt made of wire rods coated with a coating resin,

a bottom ring that is in contact with the outer end of the resin coated belt in the tire width direction is provided on the inner side of the resin coated belt in the tire radial direction,

a tire width direction inner end of the bottom ring is located on the tire width direction inner side than a tire width direction outer end of the resin coated belt, and a tire width direction outer end of the bottom ring is located on the tire width direction outer side than the tire width direction outer end of the resin coated belt,

the bottom ring has a stiffness reducing portion whose stiffness is reduced from the tire width direction outer side toward the tire width direction inner side, in a portion of the bottom ring closer to the tire width direction inner side than the tire width direction outer side end of the resin coated belt.

2. The pneumatic tire of claim 1,

the rigidity reducing portion is a tapered portion in which a thickness of the bottom ring in the tire radial direction gradually decreases from the tire width direction outer side toward the tire width direction inner side.

3. The pneumatic tire according to claim 1 or 2,

the resin-coated belt is a spiral belt formed by spirally winding a resin-coated wire material in which the wire material is coated with the coating resin.

Technical Field

The present invention relates to a pneumatic tire.

Background

Conventionally, in a pneumatic tire, in order to exert a hoop effect of fastening a carcass and improve rigidity of a tread, an operation of arranging a belt on an outer side of the carcass in a tire radial direction is generally performed (for example, patent document 1).

In recent years, in the process of increasing the demand for weight reduction of tires, a belt made of a wire material coated with a coating resin has been proposed. When such a resin-coated belt is used, the resin has higher rigidity than the weight, and therefore, the belt can function as a belt while reducing the weight.

Disclosure of Invention

Problems to be solved by the invention

However, when the resin-coated belt is used for the pneumatic tire, since the resin-coated belt has high rigidity, a large rigidity difference is abruptly generated in the tire width direction with the tire width direction end of the resin-coated belt being a boundary. Therefore, strain is likely to increase at the end of the resin-coated belt, and it is desirable to suppress occurrence of failure at the end of the resin-coated belt caused thereby.

Accordingly, an object of the present invention is to provide a pneumatic tire capable of suppressing occurrence of failure at an end portion of a resin-coated belt.

Means for solving the problems

The main structure of the present invention is as follows.

The pneumatic tire of the present invention is characterized in that,

the pneumatic tire includes a resin-coated belt composed of wire rods coated with a coating resin,

a bottom ring that is in contact with the outer end of the resin coated belt in the tire width direction is provided on the inner side of the resin coated belt in the tire radial direction,

a tire width direction inner end of the bottom ring is located on the tire width direction inner side than a tire width direction outer end of the resin coated belt, and a tire width direction outer end of the bottom ring is located on the tire width direction outer side than the tire width direction outer end of the resin coated belt,

the bottom ring has a stiffness reducing portion whose stiffness is reduced from the tire width direction outer side toward the tire width direction inner side, in a portion of the bottom ring closer to the tire width direction inner side than the tire width direction outer side end of the resin coated belt.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a pneumatic tire capable of suppressing occurrence of a failure at an end portion of a resin-coated belt.

Drawings

Fig. 1 is a schematic partial cross-sectional view in the tire width direction showing a half portion in the tire width direction of a pneumatic tire according to an embodiment of the present invention.

Fig. 2A is a partial cross-sectional view showing another example of the rigidity reducing portion together with a part of the resin-coated belt.

Fig. 2B is a partial cross-sectional view showing another example of the rigidity reducing portion together with a part of the resin-coated belt.

Fig. 2C is a partial cross-sectional view showing another example of the rigidity reducing portion together with a part of the resin-coated belt.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail by way of examples with reference to the accompanying drawings.

Fig. 1 is a schematic partial cross-sectional view in the tire width direction showing a half portion in the tire width direction of a pneumatic tire according to an embodiment of the present invention. In fig. 1, only one half in the tire width direction with the tire equatorial plane CL as a boundary is shown, and the other half is not shown, but the other half has the same configuration. The pneumatic tire 1 of the present embodiment (hereinafter also simply referred to as a tire) includes a resin-coated belt 4 composed of wire rods 4b coated with a coating resin 4a and a tread 5 in this order on the outer side in the tire radial direction of a crown portion of a carcass 3, and the carcass 3 is annularly laid over bead cores 2a embedded in a pair of bead portions 2.

In the present invention, the tire structure other than the belt structure and the structure of the after-mentioned bottom ring is not particularly limited, and can be conventionally constructed using a usual rubber.

For example, in the present embodiment, the bead core 2a formed by binding steel wires is provided, but the material and shape of the bead core are not particularly limited, or a structure without the bead core 2a may be provided. In the present embodiment, the carcass 3 is formed of a single carcass ply made of organic fibers, but the material and number of the carcass plies are not particularly limited.

In the present embodiment, the resin-coated belt 4 is a spiral belt in which a resin-coated wire material in which a coating resin 4a coats a wire material 4b is spirally wound around the tire axis. In the present invention, it is preferable that the resin-coated belt 4 is provided as one layer. This is because the resin containing the wire rods has high rigidity, and therefore, the rigidity of the tread can be sufficiently increased by one layer, and this is preferable from the viewpoint of weight reduction. The width of the resin-coated belt 4 in the tire width direction can be, for example, 90% to 120% of the tire contact width.

The wires 4b can be made of any known material, and for example, steel cords can be used. The steel cord can be, for example, a cord composed of a single filament or a multifilament of steel. In addition, organic fibers, carbon fibers, or the like can be used for the wires 4 b.

For example, a thermoplastic elastomer or a thermoplastic resin can be used as the coating resin 4a, and a resin crosslinked by heat or an electron beam or a resin cured by thermal rearrangement can be used. Examples of the thermoplastic elastomer include polyolefin thermoplastic elastomer (TPO), polystyrene thermoplastic elastomer (TPS), polyamide thermoplastic elastomer (TPA), polyurethane thermoplastic elastomer (TPU), polyester thermoplastic elastomer (TPC), and dynamic cross-linked thermoplastic elastomer (TPV). Examples of the thermoplastic resin include a polyurethane resin, a polyolefin resin, a vinyl chloride resin, and a polyamide resin. The thermoplastic resin may be, for example, one having a deflection temperature under load (under a load of 0.45 MPa) of 78 ℃ or higher as defined in ISO 75-2 or ASTM D648, a tensile yield strength of 10MPa or higher as defined in JIS K7113, a tensile elongation at break (JIS K7113) of 50% or higher as defined in JIS K7113, and a vicat softening temperature (method a) of 130 ℃ or higher as defined in JIS K7206. The tensile modulus of elasticity (defined in JIS K7113: 1995) of the coating resin 4a of the coated wire rod 4b is preferably 50MPa or more. The tensile modulus of elasticity of the coating resin 4a coating the wire rod 4b is preferably 1000MPa or less. The coating resin 4a described here does not contain rubber (an organic polymer substance exhibiting rubber elasticity at normal temperature).

The spiral belt can be formed, for example, by: the resin-coated wire rod is formed by coating the outer peripheral side of the wire rod 4b with the coating resin 4a in a molten state and solidifying the coating resin by cooling, and the resin-coated wire rod is joined by welding the resin-coated wire rods adjacent in the axial direction of the annular body formed by winding the resin-coated wire rod while melting the coating resin 4a by hot plate welding or the like. Alternatively, the spiral belt may be formed by bonding resin-coated wires adjacent in the axial direction of the formed annular body with an adhesive or the like.

As shown in fig. 1, in the tire 1 of the present embodiment, a bottom ring 6 (at least a portion of which is located at the same position in the tire width direction as the tire width direction outer end 4c of the resin coated belt 4) that is in contact with the tire width direction outer end 4c of the resin coated belt 4 is provided on the tire radial direction inner side of the resin coated belt 4. In this example, the bottom ring 6 is an annular member (which extends continuously in the tire circumferential direction in this example) made of resin. The resin may be the same as the coating resin 4a of the resin-coated belt 4, or may be a resin different from the coating resin 4a of the resin-coated belt 4. When the resin of the bottom ring 6 is different from the coating resin 4a of the resin-coated belt 4, the thermoplastic elastomer or the thermoplastic resin exemplified above can be used as the material of the coating resin 4 a.

As shown in fig. 1, the tire width direction inner end 6a of the bottom ring 6 is located inward in the tire width direction from the tire width direction outer end 4c of the resin coated belt 4, and the tire width direction outer end 6b of the bottom ring 6 is located outward in the tire width direction from the tire width direction outer end 4c of the resin coated belt 4. In the present invention, it is preferable that the width of the bottom ring 6 in the tire width direction is 7% or more of the width of the resin coated belt 4 in the tire width direction. This is because the resin-coated belt 4 (particularly, when the spiral belt is wound) can be easily arranged at the time of production by setting the ratio to 7% or more. It is also preferable that the tire width direction center position of the bottom ring 6 is set to the tire width direction outer end 4c of the resin coated belt 4 and the tire width direction position in the vicinity thereof. This is because the resin-coated belt 4 (particularly, when a spiral belt is wound) can be easily arranged during production, and the effect of reducing the difference in rigidity between the resin-coated belt 4 and rubber by the bottom ring 6, which will be described later, can be more reliably exhibited. The thickness of the bottom ring 6 may be 0.5mm to 2mm, and the distances in the tire width direction from the tire width direction outer end 4c of the resin coated belt 4 to the tire width direction inner end and outer end of the bottom ring 6 may be 0mm or more, respectively. The "width in the tire width direction" of the ground ring 6 and the resin-coated belt 4 and other dimensions in this specification are measured in a state where the tire is mounted on the application rim and filled with a predetermined internal pressure to be in an unloaded state (where "tire ground contact width" is a distance in the tire width direction between the ground contact ends in a state where the tire is mounted on the application rim and filled with the predetermined internal pressure to be in an unloaded state, with the outermost position in the tire width direction of the ground contact surface in a state where the tire is mounted on the application rim and filled with the predetermined internal pressure to be in a state where a maximum load is applied being set as the ground contact end). In the present specification, the "application Rim" refers to an industrial standard effective in a region where a tire is produced and used, and refers to JATMA YEAR BOOK of JATMA (japan automobile tire association), STANDARDS MANUAL of ETRTO (european tire and Rim technology organization) in europe, and a standard Rim (measurring Rim in STANDARDS MANUAL of ETRTO, and Design Rim in TRA YEAR BOOK) described in the united states or application sizes described in the future, such as the YEAR BOOK of TRA (tire and Rim association). The "rim" includes a dimension that will be included in the industry standard in the FUTURE, in addition to the current dimension, and examples of the "dimension described in the FUTURE" include a dimension described as "fuel DEVELOPMENTS" in STANDARDS MANUAL 2013 edition of ETRTO, and when the dimension that is not described in the industry standard is a rim having a width corresponding to the bead width of the tire. The "predetermined internal pressure" refers to an air pressure (maximum air pressure) corresponding to the tire maximum load capacity of the JATMA standard or the like in the tire of the application size. In the case of a size not described in the above-mentioned industrial standard, "predetermined internal pressure" refers to an air pressure (maximum air pressure) corresponding to a maximum load capacity predetermined for each vehicle on which the tire is mounted. The "maximum load" refers to a load corresponding to the tire maximum load capacity of the JATMA standard or the like among tires of an application size, or, in the case of a size not described in the industrial standard, a load corresponding to the maximum load capacity prescribed for each vehicle on which the tire is mounted.

Here, in the present embodiment, the bottom ring 6 has a stiffness reducing portion 6c in a portion of the bottom ring 6 on the inner side in the tire width direction than the tire width direction outer end 4c of the resin coated belt 4, and the stiffness of the stiffness reducing portion 6c is reduced from the tire width direction outer side toward the tire width direction inner side. Specifically, in the present embodiment, as shown in fig. 1, the rigidity reducing portion 6c is a tapered portion in which the thickness of the bottom ring 6 in the tire radial direction gradually decreases from the tire width direction outer side toward the tire width direction inner side. In the present embodiment, the stiffness reduced portion 6c is a tapered portion whose tire radial inner circumferential surface is linear in a cross-sectional view.

The operation and effect of the pneumatic tire of the present embodiment will be described below. In addition, in the present embodiment, the resin-coated belt 4 is formed by coating a steel wire with a coating resin 4a, and has higher rigidity than the bottom ring 6 made of resin (having no wire).

In the pneumatic tire according to the present embodiment, first, the bottom ring 6 that contacts the tire width direction outer end 4c of the resin coated belt 4 is provided on the tire radial direction inner side of the resin coated belt 4, and therefore, the rigidity step that is bounded by the tire width direction outer end 4c of the resin coated belt 4 can be relaxed, as compared with a case where a sharp rigidity step occurs between the resin coated belt 4 and rubber in the tire width direction (a case where the bottom ring 6 is not provided). On the other hand, in the case of only this structure, a large force may be applied to the resin coated belt 4 in the vicinity of the tire width direction inner end 6a of the bottom ring 6, resulting in a failure of the resin coated belt 4. In contrast, in the present embodiment, the stiffness reducing portion 6c is provided in the portion of the bottom ring 6 on the inner side in the tire width direction than the tire width direction outer end 4c of the resin coated belt 4, and the stiffness of the stiffness reducing portion 6c is reduced from the tire width direction outer side toward the tire width direction inner side (in the present embodiment, a tapered portion in which the thickness of the bottom ring 6 in the tire radial direction is gradually reduced from the tire width direction outer side toward the tire width direction inner side), so that it is possible to suppress a situation in which a large force is applied to the resin coated belt 4. In particular, in the present embodiment, since the resin coated belt 4 is a spiral belt, a failure easily occurs starting from a joint portion between adjacent resin coated wires in the axial direction of the annular body forming the spiral belt, but since a situation in which a large force is applied to the resin coated belt 4 is suppressed by the stiffness reducing portion 6c, such a failure can be suppressed.

As described above, according to the present embodiment, it is possible to suppress the occurrence of failure in the vicinity of the end portion of the resin coated belt 4 and also to suppress the occurrence of failure of the resin coated belt 4.

Further, in the present embodiment, since the bottom ring 6 is provided, when the resin-coated wire material is wound to manufacture the spiral belt, the bottom ring 6 can be wound on both sides of the winding start end side and the winding end side, and the resin-coated belt 4 can be more easily arranged, and the winding process can be more easily performed.

In the present invention, it is preferable that the rigidity reducing portion 6c is a tapered portion in which the thickness of the bottom ring 6 in the tire radial direction gradually decreases from the tire width direction outer side toward the tire width direction inner side, as in the above-described embodiment. This is because the rigidity reducing portion 6c can be formed by a simple method that facilitates molding and processing, and thus occurrence of failure in the resin-coated belt 4 can be suppressed.

On the other hand, in the present invention, the stiffness reducing portion 6c is not limited to the above example, and various stiffness reducing portions can be provided. Fig. 2A to 2C are partial cross-sectional views showing other examples of the stiffness reduced portion 6C together with a part of the resin coated belt 4. As shown in fig. 2A and 2B, the rigidity reducing portion 6c may be a tapered portion as follows: the thickness of the under ring 6 in the tire radial direction is gradually reduced from the tire width direction outer side toward the tire width direction inner side with circularity so that the tire radial direction inner peripheral surface has a (limited) curvature in section. At this time, the roundness may be formed so as to project inward in the tire radial direction as shown in fig. 2A, or may be formed so as to project outward in the tire radial direction as shown in fig. 2B. The rigidity reducing portion 6c may be formed such that the thickness of the bottom ring 6 in the tire radial direction decreases from the tire width direction outer side toward the tire width direction inner side in a stepwise manner in cross section. It is also preferable that the tire width direction outer end of the stiffness reduction portion 6c is located further outward in the tire width direction than the tire width direction outer end 4c of the resin coated belt 4.

In another embodiment, the stiffness reducing portion 6c may be formed of two or more annular members having different stiffness, and the annular member having the smaller stiffness may be disposed on the inner side in the tire width direction. In this case, the ring-shaped members having different rigidities can be joined to each other by, for example, welding or adhesion.

Further, although it is preferable that the tire width direction half portion, not shown, is also configured in the same manner, it is also possible to configure such that the bottom ring 6 is provided only in one tire width direction half portion, and it is also possible to provide the rigidity reducing portion 6c only in one tire width direction half portion of the bottom ring 6.

In the present invention, as in the above-described embodiment, the resin-coated belt 4 may be a spiral belt in which a resin-coated wire material in which a wire material 4b is coated with a coating resin 4a is spirally wound. This is because the resin-coated belt 4 can be formed by a simple method, and as described above, in the case of a spiral belt, a failure easily occurs starting from the joint between the resin-coated wires adjacent in the axial direction of the annular body, and the failure can be suppressed particularly effectively.

The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments at all. For example, in the example shown in fig. 1 and 2A to 2C, the bottom ring 6 has a shape in which the thickness is substantially constant at the outer side in the tire width direction than the tire width direction outer end 4C of the resin coated belt 4. In particular, the rigidity of the portion of the bottom ring 6 on the outer side in the tire width direction than the tire width direction outer end 4c of the resin coated belt 4 is preferably reduced from the inner side in the tire width direction toward the outer side in the tire width direction, and is preferably, for example, a tapered portion having a thickness gradually reduced from the inner side in the tire width direction toward the outer side in the tire width direction. This is because the difference in rigidity between the bottom ring 6 and the rubber can be alleviated.

Description of the reference numerals

1. A pneumatic tire; 2. a bead portion; 2a, a bead core; 3. a carcass; 4. coating a belt with resin; 4a, coating resin; 4b, wire rods; 4c, resin-coated outer ends of the belt strips in the tire width direction; 5. a tread; 6. a bottom ring; 6a, the tire width direction inner end of the bottom ring; 6b, the tire width direction outer end of the bottom ring; 6c, a rigidity reducing portion; CL, tire equatorial plane.