JP7271069B2 - pneumatic tire - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pneumatic tire capable of improving separation resistance of belt layers while suppressing excessive inflation.

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

Patent Literature 1 describes a pneumatic tire provided with a reinforcing layer mainly composed of curved cords extending in the tire circumferential direction while winding in a wavy shape. However, this reinforcing layer is a member interposed between the carcass layer and the belt layer, and the point that the ends of the belt cords in the belt layer are arranged at the ends of the belt is the same as in the conventional belt. Therefore, there is concern about the occurrence of separation starting from the belt edge, and there is room for improvement in the separation resistance of the belt layer.

Patent Literature 2 describes a tire in which the belt cord has a flat coil shape and the end of the belt cord is not arranged at the belt end. However, such a belt layer structure in which the belt cords do not extend along the tire circumferential direction is considered to be less effective in suppressing excessive inflation of the tire. Although Patent Documents 3 and 4 also describe tires in which belt cord ends are not arranged at the belt ends, the former is an aircraft tire and the latter is a two-wheeled vehicle tire, both of which are automobile tires. is different.

JP 2006-160124 A JP-A-10-217716 JP-A-11-48706 Japanese Unexamined Patent Application Publication No. 2018-43748

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

The above object can be achieved by the present invention as described below. That is, in the pneumatic tire according to the present invention, 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, Each of the first belt ply and the second belt ply is composed of a belt-like body including a pair of meandering cord groups each formed by arranging a plurality of belt cords extending in a tire circumferential direction while meandering in a wave shape, and the belt-like body In the pair of meandering cord groups included in the above, laminated portions laminated to each other in the tire radial direction and adjacent portions 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 is alternate. and the second belt ply is laminated on the outer periphery of the first belt ply in a state in which the phase of the band-shaped body is shifted with respect to the first belt ply, and the tire width direction Both ends of the belt layer in (1) are covered with a pair of belt reinforcing layers in which a plurality of reinforcing cords extending substantially in the tire circumferential direction are arranged.

In this pneumatic tire, each of the first and second belt plies is composed of a belt-like body including a pair of meandering cord groups as described above, so that the ends of the belt cords are not arranged at the ends of the belt. can improve the separation resistance of the belt layer. In addition, since the pair of meandering cord groups included in the strip are woven as described above, and the first belt ply and the second belt ply are laminated while shifting the phases of the strip, inflation is suppressed. Furthermore, since both ends of the belt layer are covered with the pair of belt reinforcing layers as described above, the unevenness of the belt cords at the belt ends is reduced, and the effect of suppressing inflation and improving the separation resistance is enhanced. be able to.

It is preferable that the belt reinforcing layer has a jointless structure. As a result, deterioration of uniformity due to the belt reinforcing layer can be suppressed.

The belt layer includes a third belt ply interposed between the carcass layer and the first belt ply, and the third belt ply extends obliquely at a predetermined angle with respect to the tire circumferential direction. It is preferable to arrange belt cords. As a result, shear strain generated between the carcass layer and the first belt ply can be reduced.

The belt layer includes a fourth belt ply that is laminated on the outer periphery of the second belt ply and arranged in the central portion of the belt layer in the tire width direction, and the fourth belt ply is arranged in the tire circumferential direction. It is preferable that a plurality of belt cords extending obliquely at a predetermined angle are arranged, and the belt reinforcing layer is arranged outside the fourth belt ply in the tire width direction with a distance of 10 mm or more. This protects the second belt ply from traumatic agents such as stones and nails, and increases the durability of the second belt ply (and the first belt ply). Further, by arranging the belt reinforcing layer apart from the fourth belt ply, it is possible to suppress the concentration of strain in the vicinity of the ends thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a tire meridian sectional view schematically showing an example of a pneumatic tire according to the present invention; A plan view showing a carcass layer, a belt layer, and a belt reinforcing layer A plan view showing a belt-shaped body constituting a first belt ply and a pair of meandering cord groups included in the belt-shaped body. A plan view showing a belt-shaped body constituting a second belt ply and a pair of meandering cord groups included in the belt-shaped body. Schematic diagram showing first and second belt plies viewed from the axial direction of the tire Schematic diagram showing a modification of the first and second belt plies viewed from the tire axial direction FIG. 4 is a cross-sectional view schematically showing a ply material constituting a belt reinforcing layer; FIG. 4 is a cross-sectional view schematically showing a ply material constituting a belt reinforcing layer; Enlarged view of main part showing belt layer and belt reinforcing layer Enlarged view of main part showing belt layer and belt reinforcing layer

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

As shown in FIG. 1, a pneumatic tire T includes a pair of bead portions 1, sidewall portions 2 extending radially outward from each of the bead portions 1, and sidewall portions 2 extending in the tire radial direction. and a tread portion 3 that continues to the outer end. The bead portion 1 is provided with an annular bead core 1a formed by rubber-coating a bundle of steel wires or the like. A tread rubber 30 is provided on the tread portion 3, and a tread pattern corresponding to the 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 frame of the tire, and a belt layer 5 that is provided on the outer circumference of the carcass layer 4 in the tread portion 3 . The carcass layer 4 extends from the bead portion 1 to the tread portion 3 via the sidewall portion 2 and is formed in a toroidal shape as a whole. The ends of the carcass layer 4 are rolled up so as to sandwich the bead core 1a. The belt layer 5 restrains the carcass layer 4 by a hoop 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 formed by arranging a plurality of carcass cords C4. Although the carcass ply 40 constituting the carcass layer 4 is one in this embodiment, it may be plural. The carcass cords C4 extend in a direction substantially orthogonal to the tire circumferential direction and are arranged in parallel in a blind shape. The inclination angle θ4 of the carcass cords 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 formed 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 is shown. Of the plurality of belt plies forming the belt layer 5, at least one of the belt ply 6 and the belt ply 7 (both in this embodiment) is the widest, and its end portion in the tire width direction constitutes the belt end. there is The belt ply 6 and the belt ply 7 have the same width, but are not limited to this.

The belt ply 6 is composed of a belt-like body 60 as shown in FIG. 3(A). The strip 60 includes a pair of meandering cord groups G6, G6 as shown in FIGS. 3(B) and 3(C). 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 as not to form an angular portion. The pair of serpentine cord groups G6, G6 are each rubber-coated and molded as a wave-like ply member. The belt-like body 60 is formed in a belt shape as a whole by combining the pair of ply members.

In the pair of meandering cord groups G6, G6 included in the belt-like body 60, laminated portions 60L laminated to each other in the tire radial direction and adjacent portions 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 is alternately replaced. Therefore, the laminated portion 60L in which one of the pair of meandering cord groups G6, G6 is positioned on the outer circumference of the other and the laminated portion 60L in which the other is positioned on the outer circumference of the other are arranged in the tire circumferential direction via the adjacent portion 60S. I'm in. In this way, in the band-shaped body 60, the laminated portions 60L and the adjacent portions 60S are periodically arranged along the tire circumferential direction.

In the laminated portion 60L, the belt cords C6 included in one of the pair of meandering cord groups G6, G6 and the belt cords C6 included in the other are inclined with respect to the tire circumferential direction so as to face in opposite directions. 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 adjoining portion 60S, a gap 61 is formed between the pair of meandering cord groups G6, G6. This allows some deformation of the band-shaped body 60, and ensures proper inflation of the tire T due to the filling of the internal pressure. 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 an organic fiber cord, for example.

The belt ply 7 is composed of a belt-like body 70 as shown in FIG. 4(A). The strip 70 includes a pair of meandering cord groups G7, G7 as shown in FIGS. 4(B) and 4(C). The meandering cord group G7 is formed by arranging a plurality of belt cords C7 extending in the tire circumferential direction while meandering in a wave shape. The pair of meandering cord groups G7, G7 are woven in the same manner as the pair of meandering cord groups G6, G6. Since the belt-like body 70 has the same configuration as the belt-like body 60, other redundant descriptions will be omitted. 3 and 4 conceptually describe the belt cords C6 and C7, respectively, and the actual arrangement pitch may be denser.

As shown in FIG. 2, the belt ply 7 is laminated on the outer circumference of the belt ply 6 in a state in which the phase of the belt-shaped body is shifted with respect to the belt ply 6 . As described above, in the band-shaped body 60, laminated portions 60L having a relatively high cord density and adjacent portions 60S having a relatively low cord density are periodically arranged along the tire circumferential direction. , and the band 70 is similarly configured. By shifting these phases, the adjacent portion 70S of the belt-shaped body 70 is arranged around the outer circumference of the laminated portion 60L of the belt-shaped body 60, and the laminated portion 70L of the belt-shaped body 70 is arranged around the outer circumference of the adjacent portion 60S of the belt-shaped body 60. be done. It is preferable that the strips 60 and 70 have the same wavelength, but have a phase shift of 180±10 degrees.

In this pneumatic tire T, each of the belt ply 6 and the belt ply 7 is composed of the band-shaped bodies 60 and 70 each including a pair of meandering cord groups as described above, so that the ends of the belt cords C6 and C7 are It is not arranged at the belt edge, thereby improving the separation resistance of the belt layer 5. - 特許庁Moreover, since the pair of meandering cord groups included in the belt-like bodies 60 and 70 are woven as described above, and the belt plies 6 and 7 are laminated while shifting the phases of the belt-like bodies 60 and 70, , the density of the belt cords is made uniform, and 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 greater than the width W6 of the belt ply 6 . If the width W7 is within 100±3% of the width W6, they are considered substantially the same. As a result, the width of the belt ply 7 becomes wider than that of a normal belt layer, the width of the belt ply 7 is sufficiently secured, and the effect of suppressing excessive inflation is enhanced. Since the ends of the belt cords C7 are not arranged at the ends of the belt, there is no problem even if the belt ply 7 is widened in this way. Such a configuration is particularly useful for tires with a low aspect ratio (%) (=section height/section width×100), such as tires with an aspect ratio of 75% or less.

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

In this embodiment, as schematically shown in FIG. 5, the belt ply 6 and the belt ply 7 are composed of a single belt-like body 60 spirally wound along the tire circumferential direction. The belt ply 6 is formed by winding a belt-like body 60 one round along the tire circumferential direction, and the belt ply 7 is formed by further winding the belt-like body 60 one round. The strip 70 forming the belt ply 7 is the same member as the strip 60 . By configuring the belt plies 6 and 7 with the belt-like body 60 wound twice in this manner, the effect of suppressing excessive inflation of the tire T is enhanced. In order to prevent the uniformity from deteriorating, it is preferable that both ends 60e, 60e of the band-shaped body 60 are aligned in the circumferential direction or are slightly spaced apart from each other so as not to overlap each other.

The belt plies 6 and 7 are not limited to the configuration shown in FIG. 5, and may be configured as shown in FIG. However, in the configuration of FIG. 5, compared with the configuration of FIG. 6, the number of joints of the band-shaped bodies 60 forming the belt plies 6 and 7 is reduced, so the uniformity of the tire T can be improved. In the modification shown in FIG. 6, the belt ply 6 is formed by winding a belt-shaped body 60 one round along the tire circumferential direction, and the belt ply 7 has a belt-shaped body 70 that is a separate member from the belt-shaped body 60. It is wound one round along the tire circumferential direction. Although conceptually depicted in FIG. 6, the ends 60e, 60e of the strip 60 preferably overlap each other so as not to open due to inflation, and the ends 70e, 70e of the strip 70 also overlap. It is the same.

As shown in FIGS. 1 and 2, in this tire T, both ends of the belt layer 5 in the tire width direction are paired with a pair of belt reinforcing layers 10 formed by arranging a plurality of reinforcing cords C10 substantially extending in the tire circumferential direction. , 10. At the belt edge, an area A1 where the belt cords are arranged relatively sparsely and an area A2 where the belt cords are arranged relatively densely appear alternately in the tire circumferential direction. The belt reinforcing layer 10 can reduce the unevenness of the belt, thereby enhancing the effect of suppressing inflation and the effect of improving separation resistance. Moreover, compared with the case where the entire belt layer 5 is covered with a single belt reinforcing layer, the increase in weight is suppressed, which contributes to weight reduction of the tire T.

In this embodiment, the above-described organic fiber cords such as nylon are used as the reinforcing cords C10. Not limited to this, for example, steel cords may be used to enhance the effect of suppressing inflation. Steel cords are preferably used as the reinforcing cords C10 in a tire having a low aspect ratio, for example, a tire having an aspect ratio of 70% or less, from the viewpoint of appropriately controlling the ground contact shape. Although the same type of reinforcing cords C10 are used for the pair of belt reinforcing layers 10, 10, it is also possible to use different types of reinforcing cords. For example, when the tread pattern is left-right asymmetrical, steel cords may be applied to one of the pair of belt reinforcing layers 10, 10, and nylon cords may be applied to the other.

In this embodiment, the belt reinforcing layer 10 has a jointless structure, and the ends thereof in the tire circumferential direction are not joined to each other. As shown in FIG. 1, the belt reinforcing layer 10 is double formed, and the reinforcing cords C10 are stacked in the tire radial direction. When the reinforcing cords C10 are organic fiber cords (for example, nylon cords), as shown in FIG. 7, the ply material 10a narrower than the belt reinforcing layer 10 is partially overlapped and spirally formed along the tire circumferential direction. The belt reinforcing layer 10 can be formed by winding. On the other hand, when the reinforcing cords C10 are steel cords, the belt reinforcing layer 10 is formed by winding a ply material 10b having a width corresponding to the belt reinforcing layer 10 two times in the tire circumferential direction, as shown in FIG. can.

The pneumatic tire according to the present invention can improve the separation resistance of the belt layer while suppressing excessive tire inflation by exerting the above effects. It is useful as a heavy-duty pneumatic tire used for 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 configured by laminating four belt plies 6 to 9, and the second and third plies function as working belts. Belt plies 6 and 7 are employed for the belt plies of the stitches. The remaining belt plies 8 and 9 will be described below.

In this 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 obliquely at a predetermined angle with respect to the tire circumferential direction. The inclination angle θ8 of the belt cord C8 with respect to the tire circumferential direction is, for example, 45±10 degrees, preferably set to 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.

Since the wavy meandering belt cords C6 are substantially perpendicular to the carcass cords C4 around the crests (or troughs) of the crests (or troughs) of the crests (or troughs) of the crests (or troughs) of the belt cords C6, there is a risk of large shear strain occurring between them. Especially when the carcass cords C4 and the belt cords C6 are steel cords, this tendency is significant. On the other hand, in the present embodiment, interposing the belt ply 8 between them makes it possible to reduce the shear strain generated between the carcass layer 4 and the belt ply 6 . The belt ply 8 is formed narrower than the belt ply 6, but 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 and arranged in the central portion of the belt layer 5 in the tire width direction. This protects the belt ply 7 from traumatic agents such as stones and nails, and furthermore protects the belt plies 6 and 7 functioning as working belts, thereby improving durability. The belt ply 9 is formed by arranging a plurality of belt cords C9 extending obliquely 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 their steps (the distance between the ends in the tire width direction) are, for example, 20 mm, but are not limited to this.

As shown in an enlarged view in FIG. 9, the belt reinforcing layer 10 is preferably arranged outside the belt ply 9 in the tire width direction (left side in FIG. 9) with a distance of 10 mm or more. That is, the distance D1 between the tire width direction inner end of the belt reinforcing layer 10 and the tire width direction outer end of the belt ply 9 is preferably 10 mm or more. As a result, it is possible to suppress the strain from concentrating in the vicinity of the ends of the belt reinforcing layer 10 and the belt ply 9 . This point is the same when the reinforcing cords 10C are steel cords. The width W10 of the belt reinforcing layer 10 is, for example, 20-40 mm.

The tire width direction outer end of the belt reinforcing layer 10 is located at the belt end or at the tire width direction outer side thereof. A distance D2 between the tire width direction outer end of the belt reinforcing layer 10 and the belt end is, for example, 0 to 10 mm, and is 0 mm in this embodiment. Accurately positioning the tire width direction outer end of the belt reinforcing layer 10 is useful for enhancing the effect of suppressing inflation. From this point of view, when forming the belt reinforcing layer 10 by winding the ply material 10a as shown in FIG. 7, it is preferable to set the winding start, which is easy to position accurately, at the outer end in the tire width direction. It is preferable to wind the ply material 10a from the outside to the inside in the tire width direction.

When the reinforcing cords 10C are steel cords, it is preferable to dispose the tire width direction outer end of the belt reinforcing layer 10 apart from the belt end as shown in FIG. 10 in an enlarged manner. Thereby, it is possible to suppress the strain from concentrating in the vicinity of those end portions. In the example of FIG. 10, the tire width direction outer end of the belt reinforcing layer 10 is separated from the belt edge toward the tire width direction inner side (right side in FIG. 10). In this case, the distance D3 between the tire width direction outer end of the belt reinforcing layer 10 and the belt end is preferably 10 mm or more.

The pneumatic tire of the present invention can be constructed in the same manner as a normal pneumatic tire except that the belt layer is constructed as described above, and any of the conventionally known materials, shapes, structures, manufacturing methods, etc. are 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. A ply member formed by coating a group of meandering cords as described above with rubber is produced by, for example, using a manufacturing apparatus described in Japanese Patent Application Laid-Open No. 2002-127711 by the applicant of the present invention to produce belt cords topped with unvulcanized rubber. It can be produced by arranging belt cords one by one or a plurality of belt cords sequentially while changing the angle of the belt cords.

The present invention is by no means limited to the above-described embodiments, and various modifications and improvements are possible without departing from the scope of the present invention.

3 tread portion 4 carcass layer 5 belt layer 6 belt ply (first belt ply)
7 belt ply (second belt ply)
8 belt ply (third belt ply)
9 belt ply (4th belt ply)
10 Belt reinforcing layer 60 Strip 60L Laminated portion 60S Adjacent portion 70 Strip C4 Carcass cord C6 Belt cord C7 Belt cord C10 Reinforcing cord G6 Meandering cord group G7 Meandering cord group

Claims (4)

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,
Each of the first belt ply and the second belt ply is formed of a belt-like body including a pair of meandering cord groups each formed by arranging a plurality of belt cords extending in the tire circumferential direction while meandering in a wave shape,
In the pair of meandering cord groups included in the belt-like body, laminated portions laminated to each other in the tire radial direction and adjacent portions adjacent to each other in the tire width direction are alternately formed in the tire circumferential direction, and are positioned in the laminated portions. The relationship is woven so that it alternates,
wherein the second belt ply is laminated on the outer periphery of the first belt ply in a phase-shifted state of the strip with respect to the first belt ply,
A pneumatic tire in which both ends of the belt layer in the tire width direction are covered with a pair of belt reinforcing layers in which a plurality of reinforcing cords extending substantially in the tire circumferential direction are arranged. The pneumatic tire according to claim 1, wherein the belt reinforcing layer has a jointless structure. The belt layer includes a third belt ply interposed between the carcass layer and the first belt ply,
3. The pneumatic tire according to claim 1 or 2, wherein the third belt ply has a plurality of belt cords arranged at a predetermined angle with respect to the tire circumferential direction. The belt layer includes a fourth belt ply that is laminated on the outer periphery of the second belt ply and arranged in the central portion of the belt layer in the tire width direction,
The fourth belt ply is formed by arranging a plurality of belt cords extending obliquely at a predetermined angle with respect to the tire circumferential direction,
The pneumatic tire according to any one of claims 1 to 3, wherein the belt reinforcing layer is arranged outside the fourth belt ply in the tire width direction at a distance of 10 mm or more.

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