JP2020104546A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire improving the separation resistance of a belt layer while suppressing excessive inflation.SOLUTION: In an objective pneumatic tire, a belt layer 5 made by laminating plural belt plies including belt plies 6 and 7 is provided at the outer peripheral side of a carcass layer 4. The belt plies 6 and 7 are composed, respectively by belt-like bodies 60 and 70 including as a pair, a meandering cord group comprising arrangement of plural belt cords extending in a tire circumferential direction while meandering in a wavy state. In a pair of the meandering cord groups included in the belt-like bodies 60 and 70, the lamination part laminated mutually in a tire radial direction and the adjacent part mutually adjacent in a tire width direction are alternately formed in the tire circumferential direction and are woven so that physical relationships in the lamination part counterchange mutually. The belt ply 7 is laminated on the outer periphery of the belt ply 6 in such a state as displacing the phase of the belt-like body for the belt ply 6.SELECTED DRAWING: Figure 2

Description

The present invention relates to a pneumatic tire capable of improving the separation resistance of a belt layer while suppressing excessive inflation.

The belt layer of the pneumatic tire restrains the carcass layer by a broom effect and suppresses excessive inflation (expansion deformation) of the tire due to internal pressure filling. The belt layer is composed of a plurality of belt plies that are laminated on each other. The belt ply is formed by arranging a plurality of belt cords extending obliquely with respect to the tire circumferential direction, and an end portion of each belt cord is arranged at a belt end. Since the end of the belt cord has poor adhesion with rubber, when the belt end where the end of the belt cord is arranged is repeatedly subjected to strain due to strain deformation of the tire during running, the belt end is regarded as the starting point. There is concern about the occurrence of separation.

Patent Document 1 describes a pneumatic tire including a reinforcing layer mainly including a detouring cord extending in the tire circumferential direction while curving in a wave shape. However, the reinforcing layer is a member interposed between the carcass layer and the belt layer, and the end of the belt cord in the belt layer is arranged at the belt end, which is the same as in the conventional case. Therefore, there is a concern that separation may occur starting from the belt end, and there is room for improvement in the separation resistance of the belt layer.

Patent Document 2 describes a tire in which the belt cord has a flat coil shape and the end portion of the belt cord is not arranged at the belt end. However, in such a structure of the belt layer in which the belt cord does not extend in the tire circumferential direction, it is considered that the effect of suppressing excessive inflation of the tire is poor. Although Patent Documents 3 and 4 also describe tires in which the ends of the belt cords are not arranged at the belt ends, the former are aircraft tires and the latter are motorcycle tires, both of which are automotive tires. Is different.

JP, 2006-160124, A JP, 10-217716, A JP, 11-48706, A JP, 2018-43748, A

The present invention has been made in view of the above circumstances, and an object thereof is to provide a pneumatic tire capable of improving the separation resistance of a belt layer while suppressing excessive inflation.

The above object can be achieved by the present invention as described below. That is, the pneumatic tire according to the present invention is provided with a belt layer formed by laminating a plurality of belt plies including the first belt ply and the second belt ply on the outer peripheral side of the carcass layer in the tread portion, Each of the first belt ply and the second belt ply is formed of a band-shaped body including a pair of meandering cord groups formed by arranging a plurality of belt cords extending in the tire circumferential direction while meandering in a wavy shape. In the pair of meandering cord groups included in, the laminated portions that are laminated in the tire radial direction and the adjacent portions that are adjacent to each other in the tire width direction are alternately formed in the tire circumferential direction, and the positional relationship in the laminated portions alternates. The second belt ply is laminated on the outer periphery of the first belt ply in a state in which the phase of the belt-shaped body is shifted with respect to the first belt ply.

In this pneumatic tire, since each of the first and second belt plies is composed of a strip-shaped body including a pair of the meandering cord groups as described above, the end portion of the belt cord is not arranged at the belt end. Thereby, the separation resistance of the belt layer can be improved. In addition, since the pair of meandering cord groups included in the belt-like body are woven as described above, and the first belt ply and the second belt ply are laminated by shifting the phases of the belt-like bodies from each other, the tire is excessively Inflation is suppressed.

It is preferable that the width of the second belt ply is substantially the same as or larger than the width of the first belt ply. As a result, the width of the second belt ply is sufficiently secured, and the effect of suppressing excessive inflation of the tire is enhanced.

It is preferable that the first belt ply and the second belt ply are formed of the single strip-shaped body that is spirally wound in the tire circumferential direction. According to this structure, the number of joint portions of the belt-shaped body is reduced, so that the uniformity of the tire can be improved.

The belt layer includes a third belt ply interposed between the carcass layer and the first belt ply, and the third belt ply is inclined at an angle of 45±10 degrees with respect to a tire circumferential direction. It is preferable that a plurality of extending belt cords are arranged. This can reduce the shear strain generated between the carcass layer and the first belt ply.

It is preferable that the belt layer includes a fourth belt ply laminated on the outer periphery of the second belt ply. As a result, the second belt ply can be protected from trauma factors such as stones and nails, and the durability of the second belt ply (and the first belt ply) can be enhanced.

A tire meridian sectional view schematically showing an example of a pneumatic tire according to the present invention The top view which shows a carcass layer and a belt layer The top view which shows the strip|belt-shaped body which comprises a 1st belt ply, and a pair of meandering code group contained in the strip|belt-shaped object. The top view which shows the strip|belt-shaped body which comprises a 2nd belt ply, and a pair of meandering code group contained in the strip|belt-shaped object. Schematic which shows the 1st and 2nd belt ply seen from the tire axial direction. Schematic which shows the modification of the 1st and 2nd belt ply seen from the tire axial direction.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the pneumatic tire T includes a pair of bead portions 1, sidewall portions 2 extending outward from each of the bead portions 1 in the tire radial direction, and each of the sidewall portions 2 in the tire radial direction. And a tread portion 3 connected to the outer end. The bead portion 1 is provided with an annular bead core 1a formed by coating a converging body such as a steel wire with rubber. A tread rubber 30 is provided on the tread portion 3, and a tread pattern according to required tire performance and usage conditions is formed on the outer peripheral surface thereof.

The pneumatic tire T further includes a carcass layer 4 that forms the skeleton of the tire, and a belt layer 5 that is provided on the outer periphery of the carcass layer 4 in the tread portion 3. The carcass layer 4 extends from the bead portion 1 to the sidewall portion 2 to the tread portion 3, and is formed in a toroidal shape as a whole. The end portion of the carcass layer 4 is wound up so as to sandwich the bead core 1a. The belt layer 5 restrains the carcass layer 4 by a broom effect and suppresses excessive inflation of the tire T due to internal pressure filling. The belt layer 5 is arranged inside the tread rubber 30 in the tire radial direction.

As shown in FIG. 2, the carcass layer 4 is composed of a carcass ply 40 in which a plurality of carcass cords C4 are arranged. In the present embodiment, the number of the carcass ply 40 that constitutes the carcass layer 4 is one, but it may be two or more. The carcass cords C4 extend in a direction substantially orthogonal to the tire circumferential direction and are arranged in parallel to each other like a blind. The inclination angle θ4 of the carcass cord C4 with respect to the tire circumferential direction is, for example, 90±5 degrees. Steel cords are preferably used for the carcass cord C4 from the viewpoint of durability, but organic fiber cords such as polyester, rayon, nylon, and aramid can also be used.

The belt layer 5 is configured by laminating a plurality of belt plies including a belt ply 6 (first belt ply) and a belt ply 7 (second belt ply). In this embodiment, an example in which the belt layer 5 is composed of four belt plies 6 to 9 will be described. At least one of the belt ply 6 and the belt ply 7 (both in the present embodiment) is the widest of the plurality of belt plies forming the belt layer 5, and the end portion in the tire width direction forms the belt end. There is. The belt ply 6 and the belt ply 7 have the same width, but the width is not limited to this.

The belt ply 6 is composed of a belt-shaped body 60 as shown in FIG. The band-shaped body 60 includes a pair of meandering code groups G6 and G6 as shown in FIGS. 3B and 3C. The meandering cord group G6 is formed by arranging a plurality of belt cords C6 extending in the tire circumferential direction while meandering in a wave shape. Each belt cord C6 is curved in a sinusoidal shape so that an angular portion is not formed. Each of the pair of meandering cord groups G6 and G6 is covered with rubber and molded as a corrugated ply member. The strip-shaped body 60 is formed in a strip shape as a whole by combining the pair of ply members.

In the pair of meandering cord groups G6 and G6 included in the belt-shaped body 60, a laminated portion 60L laminated in the tire radial direction and an adjacent portion 60S adjacent to each other in the tire width direction are alternately formed in the tire circumferential direction and laminated. It is woven so that the positional relationship in the portion 60L alternates. Therefore, the laminated portion 60L in which one of the pair of meandering cord groups G6 and G6 is located on the outer circumference of the other and the laminated portion 60L of which the other is located on the one outer circumference are arranged in the tire circumferential direction via the adjacent portion 60S. I'm out. As described above, the laminated portion 60L and the adjacent portion 60S are periodically arranged on the strip 60 along the tire circumferential direction.

In the laminated portion 60L, the belt cord C6 included in one of the pair of meandering cord groups G6 and G6 and the belt cord C6 included in the other are inclined with respect to the tire circumferential direction so as to be opposite to each other. There is. In the laminated portion 60L, the inclination angle θ6 of the belt cord C6 with respect to the tire circumferential direction is, for example, 20±5 degrees. In the adjacent portion 60S, a gap 61 is formed between the pair of meandering cord groups G6 and G6. As a result, the deformation of the belt-shaped body 60 is allowed to some extent, and an appropriate inflation of the tire T due to the internal pressure filling is secured. A steel cord is preferably used for the belt cord C6 from the viewpoint of suppressing excessive inflation of the tire T, but the belt cord C6 is not limited to this and may be, for example, an organic fiber cord.

The belt ply 7 is composed of a belt-shaped body 70 as shown in FIG. The strip-shaped body 70 includes a pair of meandering cord groups G7 and G7 as shown in FIGS. 4B and 4C. The meandering cord group G7 is formed by arranging a plurality of belt cords C7 that meander in a wave shape and extend in the tire circumferential direction. The pair of meandering cord groups G7 and G7 are woven in the same manner as the pair of meandering cord groups G6 and G6. Since the band-shaped body 70 has the same configuration as the band-shaped body 60, other duplicate description will be omitted. In FIGS. 3 and 4, the belt cords C6 and C7 are conceptually described, and the actual arrangement pitch may be more dense.

As shown in FIG. 2, the belt ply 7 is laminated on the outer circumference of the belt ply 6 in a state where the phase of the belt-shaped body is shifted with respect to the belt ply 6. As described above, in the belt-shaped body 60, the laminated portion 60L having a relatively high cord density and the adjacent portion 60S having a relatively low cord density are periodically arranged along the tire circumferential direction. The strip 70 is arranged in the same manner. By shifting these phases, the adjacent portion 70S of the strip 70 is arranged on the outer periphery of the laminated portion 60L of the strip 60, and the laminated portion 70L of the strip 70 is arranged on the outer periphery of the adjacent portion 60S of the strip 60. To be done. It is preferable that the strip 60 and the strip 70 have the same wavelength but are out of phase with each other within a range of 180±10 degrees.

In the pneumatic tire T, since the belt ply 6 and the belt ply 7 are each composed of the strip-shaped bodies 60 and 70 including the pair of meandering cord groups as described above, the end portions of the belt cords C6 and C7 are The separation resistance of the belt layer 5 can be improved because it is not arranged at the belt end. Further, since the pair of meandering cord groups included in the strips 60 and 70 are woven as described above, and the belt ply 6 and the belt ply 7 are laminated by shifting the phases of the strips 60 and 70 from each other. Therefore, the density of the belt cords is made uniform, and the excessive inflation of the tire T is suppressed.

As described above, in this embodiment, the belt ply 6 and the belt ply 7 have the same width. The width W7 of the belt ply 7 is preferably substantially the same as or larger than the width W6 of the belt ply 6. If the width W7 is within the range of 100±3% of the width W6, it is assumed that they are substantially the same. As a result, the belt ply 7 becomes wider than the ordinary belt layer, and the effect of suppressing excessive inflation is enhanced. Since the end of the belt cord C7 is not arranged at the belt end, there is no problem in widening the belt ply 7 in this way. Such a configuration is particularly useful for a tire having a low flatness (%) (=section height/section width×100), for example, a tire having a flatness of 75% or less.

The width of the widest belt ply among the belt plies forming the belt layer 5, that is, the widths W6 and W7 of the belt plies 6 and 7 in this embodiment is preferably 85 to 95% of the ground contact width CW. .. The ground contact end CE is the outermost position in the tire axial direction of the ground contact surface when the internal pressure and load based on JASO-C607 are applied, and the tire axial direction distance between the ground contact ends CE is the ground contact width CW.

In the present embodiment, as schematically shown in FIG. 5, the belt ply 6 and the belt ply 7 are composed of a single strip 60 wound in a spiral shape along the tire circumferential direction. The belt ply 6 is formed by winding the belt-shaped body 60 once around the tire circumferential direction, and the belt ply 7 is formed by further winding the belt-shaped body 60 once around the tire. The belt-shaped body 70 forming the belt ply 7 is the same member as the belt-shaped body 60. By constructing the belt plies 6 and 7 with the belt-like body 60 that is wound twice, the effect of suppressing excessive inflation of the tire T is enhanced. In order to prevent the deterioration of uniformity, it is preferable that both end portions 60e, 60e of the strip-shaped body 60 have their circumferential positions aligned with each other or are slightly separated from each other and do not overlap each other.

The belt plies 6 and 7 are not limited to the configuration shown in FIG. 5 and may have the configuration illustrated in FIG. However, in the configuration of FIG. 5, as compared with the configuration of FIG. 6, the number of joint portions of the belt-shaped body 60 forming the belt plies 6 and 7 is reduced, and thus the uniformity of the tire T can be improved. In the modified example shown in FIG. 6, the belt ply 6 is formed by winding the belt-shaped body 60 once around the tire circumferential direction, and the belt ply 7 is provided with a belt-shaped body 70 that is a member separate from the belt-shaped body 60. It is made to wind once around the tire circumferential direction. Although not shown conceptually in FIG. 6, it is preferable that both end portions 60e and 60e of the belt-shaped body 60 overlap with each other so as not to be opened by inflation, and the both end portions 70e and 70e of the belt-shaped body 70 are also overlapped with this. The same is true.

The pneumatic tire according to the present invention can improve the separation resistance of the belt layer while suppressing the excessive inflation of the tire by exerting the above-mentioned effects, and thus the weight of the vehicle such as trucks, buses, industrial vehicles, and construction vehicles. It is useful as a heavy-duty pneumatic tire used in heavy vehicles. The tire T of the present embodiment is an example of such a heavy duty pneumatic tire in which the belt layer is formed by laminating four belt plies 6 to 9, and the second and third sheets functioning as working belts. Belt plies 6 and 7 are used for the eye belt ply. The remaining belt plies 8 and 9 will be described below.

In the present embodiment, the belt layer 5 includes a belt ply 8 (third belt ply) interposed between the carcass layer 4 and the belt ply 6. As shown in FIG. 2, the belt ply 8 is formed by arranging a plurality of belt cords C8 extending at an angle of 45±10 degrees with respect to the tire circumferential direction. That is, the inclination angle θ8 of the belt cord C8 with respect to the tire circumferential direction is 45±10 degrees, and is set to, for example, 50 to 55 degrees. A steel cord is preferably used for the belt cord C8 from the viewpoint of durability, but an organic fiber cord can also be used, and this point is the same for the belt cord C9 described later.

Since the belt cord C6 meandering in a wave shape is substantially orthogonal to the carcass cord C4 around the peaks (or valleys) of the wave, a large shear strain may occur between them. Especially when the carcass cord C4 and the belt cord C6 are steel cords, the tendency is large. On the other hand, in the present embodiment, by interposing the belt ply 8 between them, it is possible to reduce the shear strain generated between the carcass layer 4 and the belt ply 6. The belt ply 8 is formed to be narrower than the belt ply 6, but the width is not limited to this.

In the present embodiment, the belt layer 5 includes a belt ply 9 (fourth belt ply) laminated on the outer periphery of the belt ply 7. As a result, the belt ply 7 can be protected from trauma factors such as stones and nails, and in turn, the belt plies 6 and 7 functioning as working belts can be protected and durability can be improved. The belt ply 9 is formed by arranging a plurality of belt cords C9 that extend at a predetermined angle with respect to the tire circumferential direction. The inclination angle θ9 of the belt cord C9 with respect to the tire circumferential direction is, for example, 20±5 degrees. The belt ply 9 is formed narrower than the belt ply 7, and the steps (distance between the end portions in the tire width direction) are, for example, 20 mm, but are not limited thereto.

On the outer periphery of the belt layer 5, a belt reinforcing layer formed by arranging a plurality of reinforcing cords substantially extending in the tire circumferential direction may be laminated in order to improve high-speed durability. Such a belt reinforcing layer can be formed by spirally winding one or a plurality of rubber-coated reinforcing cords. An organic fiber cord is preferably used as the reinforcing cord. However, in the present invention, the belt reinforcing layer is not an essential configuration and can be omitted as in the present embodiment. In this way, if the belt reinforcing layer is omitted and the tread rubber 30 is directly laminated on the outer periphery of the belt layer 5, it is possible to avoid the weight increase due to the belt reinforcing layer and reduce the rolling resistance.

The pneumatic tire of the present invention can be configured in the same manner as a normal pneumatic tire except that the belt layer is configured as described above, and any conventionally known material, shape, structure, manufacturing method or the like is adopted in the present invention. be able to.

The pneumatic tire of the present invention can be manufactured in the same manner as in the conventional tire manufacturing process, except that the belt layer is modified as described above. The ply member obtained by coating the meandering cord group with rubber as described above uses, for example, a belt cord topped with unvulcanized rubber by using the manufacturing apparatus described in JP-A-2002-127711 by the present applicant. It can be manufactured by arranging one by one or plural ones sequentially and changing the angle of the belt cord.

The present invention is not limited to the embodiments described above, and various improvements and modifications can be made without departing from the spirit of the present invention.

3 Tread Part 4 Carcass Layer 5 Belt Layer 6 Belt Ply (First Belt Ply)
7 Belt ply (2nd belt ply)
8 Belt plies (3rd belt ply)
9 Belt ply (4th belt ply)
60 Belt 60L Laminated part 60S Adjacent part 70 Belt C4 Carcass cord C6 Belt cord C7 Belt cord G6 Meandering cord group G7 Meandering cord group

Claims (5)

A belt layer formed by laminating a plurality of belt plies including a first belt ply and a second belt ply is provided on the outer peripheral side of the carcass layer in the tread portion,
The first belt ply and the second belt ply are each formed of a band-shaped body including a pair of meandering cord groups formed by arranging a plurality of belt cords extending in the tire circumferential direction while meandering in a wavy manner,
The pair of meandering cord groups included in the band-shaped body, the laminated portions laminated in the tire radial direction and the adjacent portions adjacent to each other in the tire width direction are alternately formed in the tire circumferential direction, and the position in the laminated portion. It is woven so that the relationships alternate with each other,
A pneumatic tire in which the second belt ply is laminated on the outer periphery of the first belt ply in a state in which the phase of the belt-shaped body is shifted with respect to the first belt ply. The pneumatic tire according to claim 1, wherein the width of the second belt ply is substantially the same as or larger than the width of the first belt ply. The pneumatic tire according to claim 1 or 2, wherein the first belt ply and the second belt ply are configured by the single strip-shaped body that is spirally wound along a tire circumferential direction. The belt layer includes a third belt ply interposed between the carcass layer and the first belt ply,
The pneumatic tire according to any one of claims 1 to 3, wherein the third belt ply has a plurality of belt cords arranged to extend at an angle of 45 ± 10 degrees with respect to the tire circumferential direction. The pneumatic tire according to any one of claims 1 to 4, wherein the belt layer includes a fourth belt ply laminated on the outer circumference of the second belt ply.

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