JP2000203215A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively restrain separation in the vicinity of a width-directional outer end of the widest reinforcing ply, while restraining diameter growth of a tread part. SOLUTION: When a width-directional outer end 34 of the widest reinforcing plies 32a, 32b is positioned in a width-directional outer side more outer than a width-directional outer end 35 of the widest belt ply 25a, a rubber in the vicinity of the outer end 34 is separated from the outer end 35 of the ply 25a deformed greately to a circumferential direction to be hardly affected by the deformation hereinbefore. Strain of the rubber positioned in the vicinity of the outer end 34 of the plies 32a, 32b is reduced thereby to effectively restrain separation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire in which a belt reinforcing layer in which a reinforcing element extending in a circumferential direction while bending in a wavy manner is embedded is superposed on the belt layer.

[0002]

2. Description of the Related Art A conventional pneumatic tire provided with a belt reinforcing layer for reinforcing a belt layer is disclosed in
Japanese Patent Application Laid-Open No. 208101 is known. This is a carcass layer extending in a toroidal shape between the beads, and at least two belt plies embedded with a reinforcing cord disposed radially outside the carcass layer and inclined in a direction opposite to the tire equatorial plane. And a reinforcing element that is arranged radially inward of the belt layer so as to overlap with the belt layer, is narrower than the belt layer, and has a reinforcing element that extends in the circumferential direction while being bent in a wavy or zigzag shape. The belt includes a belt reinforcing layer composed of at least one reinforcing ply, and a tread rubber disposed radially outside the belt layer and the belt reinforcing layer.

[0003] The belt reinforcing layer of such a pneumatic tire suppresses radial growth of a tread portion, particularly a shoulder portion, in a radially outward direction caused by filling the tire with an internal pressure. The belt durability is improved by suppressing the separation at the outer end in the width direction.However, since the diameter growth of the tread portion increases with the flattening of the tire, the belt reinforcing layer increases as the tire becomes flatter. Is also wide.

[0004]

However, in such a pneumatic tire, if the width of the belt reinforcing layer is further increased in accordance with the recent flattening of the tire (the flattening ratio is 0.70 or less), There is a problem that separation may occur at the widthwise outer end of the belt reinforcing layer.

[0005]

The inventor of the present invention has conducted intensive studies on such separation of the belt reinforcing layer, and has obtained the following findings. That is, the belt layer in the ground contact area is deformed so as to be flat and the reinforcing cord is inclined toward the tire equatorial plane, so that it is deformed so as to expand in the circumferential direction. Drags the surrounding rubber in the circumferential direction, and the amount of drag of the rubber increases as approaching the widthwise outer end of the belt layer. Here, since a belt reinforcing layer narrower than the belt layer is disposed on the belt layer, the rubber in the vicinity of the width direction outer end of the belt reinforcing layer is pulled toward the width direction outer end of the belt layer. However, even if the belt reinforcing layer is deformed so as to be flat with the belt layer, the inner reinforcing element extends in the circumferential direction, and thus does not expand in the circumferential direction. Large distortion occurs in the rubber near the widthwise outer end of the belt reinforcing layer, and moreover,
Such distortion is repeatedly generated by the rotation of the tire. From such a fact, it has been found that when the belt reinforcing layer becomes wide, a large strain is repeatedly generated in the rubber near the outer end in the width direction and separation occurs early.

Based on such findings, the present inventor has conducted further studies, and if the rubber in the vicinity of the widthwise outer end of the belt reinforcing layer is separated from the widthwise outer end of the belt layer which is largely deformed in the circumferential direction. It has been found that the occurrence of separation can be suppressed.

The present invention has been made on the basis of such findings, and includes a carcass layer extending between beads in a toroidal shape, and a carcass layer disposed radially outside of the carcass layer and inclined in the opposite direction to the tire equatorial plane. A belt layer composed of at least two belt plies having embedded therein reinforcing cords, and at least one embedded reinforcing element disposed inside the belt layer and extending in the circumferential direction while being bent in a wavy or zigzag shape. In a pneumatic tire provided with a belt reinforcing layer composed of two reinforcing plies, and a tread rubber disposed radially outside the belt layer and the belt reinforcing layer, the widthwise outer end of the widest widest reinforcing ply has the largest width. This can be achieved by arranging the widest belt ply, which is the widest in width, outside the widthwise outer end of the widest belt ply.

As described above, if the widthwise outer end of the widest widest reinforcement ply is disposed outside the widthwise outer end of the widest widest belt ply, the width of the widest reinforcement ply can be reduced. The rubber near the outer end in the direction is separated in the width direction from the outer end in the width direction of the widest belt ply that largely deforms in the circumferential direction, so that it is less affected by the deformation,
Thereby, the separation near the widthwise outer end of the widest reinforcement ply is effectively suppressed. Here, the belt reinforcing layer and the belt layer can have three kinds of radial positional relationships as in claims 4, 5 and 6.

Further, according to the second aspect of the present invention, while preventing separation at the widthwise outer end of the widest reinforcing ply, the diameter growth of the tread portion is effectively suppressed to make the distribution uniform. can do. further,
According to the third aspect of the invention, the influence of the circumferential deformation of the widest belt ply on the vicinity of the outer end in the width direction of the widest reinforcing ply is almost eliminated, so that the separation at the portion is more strongly suppressed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. 1 and 2, reference numeral 11 denotes a heavy-duty pneumatic radial tire having an aspect ratio of 0.70 or less, which is mounted on a truck, a bus, or the like.
Are respectively buried, a pair of bead portions 13, sidewall portions 14 each extending substantially radially outward from these bead portions 13, and a substantially cylindrical shape connecting radially outer ends of these sidewall portions 14. A tread portion 15 is provided. And this pneumatic tire 11 is
12 has a carcass layer 18 extending in a toroidal shape between the side walls 14 and the tread portion 15, and both end portions of the carcass layer 18 extend around the bead 12 from the inside in the axial direction to the outside in the axial direction. It is folded. The carcass layer
18 is at least one, here one carcass ply 19
In the carcass ply 19, a number of non-extensible cords 20, for example, steel cords extending in the radial direction (meridian direction) are embedded. A chafer 21 reinforced with, for example, a steel cord is arranged around the carcass layer 18 in the bead portion 13.

Reference numeral 24 denotes a belt layer disposed radially outside the carcass layer 18. The belt layer 24 is formed by laminating at least two (here, two) belt plies 25. A large number of non-extensible reinforcing cords 26 made of, for example, steel or aramid fiber are buried inside the 25. The reinforcing cords 26 buried in the belt plies 25 correspond to the tire equatorial plane S.
It is inclined at 10 to 70 degrees, and at least two belt plies 25 have opposite inclination directions. Here, the inner belt ply 25a located on the radially inner side is wider than the outer belt ply 25b located on the radially outer side. As a result, in this embodiment, the inner belt ply 25a is Ply, outer belt ply
25b is the next width belt ply. The widthwise outer end of the widest belt ply 25a and the next width belt ply 25
A cushion rubber 27 for relieving the distortion between them is interposed between the outer end of the b in the width direction.

Reference numeral 28 denotes a tread rubber disposed radially outside the carcass layer 18 and the belt layer 24, and 29 denotes a carcass layer 18
The side rubbers are arranged on both outer sides in the axial direction.

Reference numeral 31 denotes a belt reinforcing layer disposed radially inside the belt layer 24 and radially outside the carcass layer 18, that is, between the belt layer 24 and the carcass layer 18 so as to overlap with the belt layer 24. At least one belt reinforcing layer 31;
Here, it is composed of two laminated reinforcing plies 32. The interior of each reinforcing ply 32 extends substantially circumferentially,
A reinforcing element 33 made of a non-extensible material such as steel or aramid fiber is embedded, and the reinforcing element 33 is made of cord (stranded wire) or monofilament,
Many appear in the meridian section of each reinforcement ply 32. And
The reinforcing elements 33 are bent in a wave shape or a zigzag shape, for example, in a square wave, a triangular wave, or a sine wave shape in a plane parallel to the front and back surfaces of the reinforcing ply 32, and are arranged in the same phase. Here, the inner reinforcing ply located on the radially inner side
The outer reinforcement ply 32b adjacent to the widest belt ply 25a and located radially outward has the same width, and as a result, both reinforcement plies 32a and 32b are the widest reinforcement plies. Further, each reinforcing ply 32 is configured by, for example, arranging a small number of reinforcing elements 33 in a spiral manner around the outside of the carcass layer 18 many times around a rubber-coated ribbon-shaped body.

The widest reinforcing plies 32a, 32b
Are located outside the widthwise outer end 35 of the widest belt ply 25a in the widthwise direction. As a result, the rubber near the widthwise outer ends of the widest wide reinforcing plies 32a and 32b is deformed greatly in the circumferential direction.
Since the widthwise distance from the widthwise outer end 35 of the 25a is less affected by the deformation, distortion of the rubber located in the vicinity of the widthwise outer ends 34 of the widest reinforcing plies 32a and 32b is reduced. The separation is effectively suppressed. Reference numeral 36 denotes a cushion rubber layer interposed between the widthwise outer end of the belt reinforcing layer 31 and the carcass layer 18.

Here, of the tread portion 15, the portion where the diameter grows the largest when the internal pressure is filled is the carcass layer 18.
Assuming that the maximum carcass width is L, the carcass is generally located between a point R 0.325 times the carcass maximum width L and a point P 0.375 times away from the tire equatorial plane S in the width direction. Therefore, in order to strongly restrain such diameter growth and to make the diameter growth uniform at the tread portion 15, the widest reinforcing ply 32 is required.
It is preferable that the widthwise outer ends 34 of a and b are located outside the point P in the widthwise direction. However, when the widthwise outer ends 34 of the widest width reinforcing plies 32a and 32b are positioned outwardly in the widthwise direction from the tire equatorial plane S and 0.45 times the maximum width L of the carcass, the widest width reinforcement is obtained. Ply 32
Since the separation may occur at the widthwise outer ends 34 of a and b, it is preferable that the widthwise outer ends 34 of the widest widening reinforcing plies 32a and b are located inward of the point Q in the widthwise direction. For these reasons, the widest widening ply 32
The widthwise outer ends 34 of a and b are preferably located between points P and Q.

Assuming that the entire width of the widest belt ply 25a is N, the outer ends 34 in the width direction of the widest reinforcing plies 32a and 32b are the outer ends 35 in the width direction of the widest belt ply 25a.
Is preferably located on the outer side in the width direction from a point U separated outward by 0.05 times the width N from the width direction. The reason for this is that, in this case, the widthwise outer ends 34 of the widest reinforcing plies 32a and 32b are located at the widthwise outer ends of the widest belt ply 25a.
Since it is largely separated in the width direction from 35, the influence of the circumferential deformation of the widest belt ply 25a on the rubber in the vicinity of the width direction outer end 34 is almost eliminated, and thereby the separation at the portion can be more strongly suppressed. Because you can.

Here, of the belt plies 25 constituting the belt layer 24, the belt plies arranged on the outermost side in the radial direction, in this embodiment, the tire of the reinforcing cord 26 embedded in the next width belt plies 25b When the inclination angle with respect to the equatorial plane S is less than 30 degrees (22 degrees in this case), the belt ply 25b bears a considerable tension. The reinforcing cord 26 in the ply 25b may be cut. For this reason, in this embodiment, a protective layer comprising at least one protective ply 38 is provided radially outside the next width belt ply 25b.
39 is arranged to suppress the cutting of the reinforcing cord 26 described above. Here, in order to suppress the cutting of the reinforcing cord 26 in this manner, the protective layer 39 is, for example, made to have a cord inclination angle equal to or greater than the cord inclination angle of the belt ply 25, and the tension load of the protection layer 39 itself is reduced as much as possible. It may be configured as follows. In the protective ply 38 constituting the protective layer 39, a large number of non-extensible cords 40 made of, for example, steel or aramid fiber, which are inclined with respect to the tire equatorial plane S, are embedded. The total width B of the protective layer 39 is 0.3 times the maximum width L of the carcass to the widest reinforcing ply 32a,
It is preferable that the width be equal to b. The reason is the protective layer
If the width B of 39 is less than 0.3 times the maximum width L of the carcass, it may not be possible to cover the region where the tension of the belt layer 24 is high. On the other hand, if the width B of the widest reinforcement ply 32a, b is exceeded, This is because separation occurs at the outer end in the width direction of the protective layer 39.

In the above-described embodiment, the belt reinforcing layer 31 is disposed radially inside the belt layer 24. However, in the present invention, between the belt plies constituting the belt layer, for example, the next largest belt ply A belt reinforcement layer may be arranged between the belt ply and the width belt ply,
The belt reinforcing layer may be arranged radially outside the belt layer. Here, in the case of the latter, since the reinforcing element in the reinforcing ply extending in the circumferential direction may be cut by a projection input, the same protective layer as the above-described protective layer may be provided radially outside the belt reinforcing layer. Is preferably arranged.

[0019]

Next, test examples will be described. In this test, a belt reinforcing layer was disposed between the carcass layer and the belt layer, and the widthwise outer end of the widest reinforcing ply of the belt reinforcing layer was positioned inside the widthwise outer end of the widest belt ply in the widthwise direction. And a belt reinforcing layer disposed radially outward of the belt layer, and the widthwise outer end of the widest reinforcing ply of the belt reinforcing layer is wider than the widthwise outer end of the widest belt ply. The conventional tire 2 positioned on the inner side in the direction, the belt reinforcing layer is disposed between the carcass layer and the belt layer, and the widthwise outer end of the widest reinforcing ply of the belt reinforcing layer is set in the width direction of the widest belt ply. Test tires 1 to 15 positioned outside in the width direction from the outer end
A belt reinforcing layer disposed radially outward of the belt layer, and the widthwise outer end of the widest reinforcing ply of the belt reinforcing layer is positioned outside the widthwise outer end of the widest belt ply. A belt reinforcing layer is arranged between the test tires 16 and 17 and a belt ply constituting the belt layer, and a widthwise outer end of the widest reinforcing ply of the belt reinforcing layer is wider than a widthwise outer end of the widest belt ply. Test tires 18 to 22 positioned outside in the direction were prepared. Here, the radial outside of the belt layer of the conventional tire 1, the radial outside of the belt reinforcing layer of the conventional tire 2, the test tires 1 to 1
A protective layer for protecting the belt layer or the belt reinforcing layer is provided on the outer side in the radial direction of the first belt layer, the outer side of the belt reinforcing layer of the test tires 16 and 17 and the outer side of the outermost belt ply of the test tire 18. Is arranged.

Here, the size of each tire is 285 / 60R2
2.5. In Tables 1 and 2 below, the half width (half width of the inner belt ply / half width of the outer belt ply) of the two belt plies constituting the belt layer of each tire is expressed in units of mm.
The inclination angle of the reinforcement cord embedded in each belt ply with respect to the tire equatorial plane (the inclination angle of the reinforcement cord in the inner belt ply / the inclination angle of the reinforcement cord in the outer belt ply) is expressed in units of the widest reinforcement ply. The half width of the unit in mm,
The value F obtained by dividing the half width of the widest reinforcement ply by the maximum width L of the carcass, the value G obtained by subtracting the half width of the widest belt ply from the half width of the widest reinforcement ply by the full width of the widest belt ply, and the value of the protective layer The half width is shown in units of mm.

[0021]

[Table 1]

[Table 2]

Next, each of these tires has a size of 9.00 × 2
It was mounted on a 2.5 rim and filled with an internal pressure of 9.0 kgf / cm ² , and the maximum diameter growth in the tread portion was measured. The results are shown in Tables 1 and 2 in percent. Next, 50
The belt was run on a drum at a speed of 60 km / h under a load of 00 kg until separation occurred at the widthwise outer end of the belt reinforcing layer. Tables 1 and 2 show the results for Conventional Tire 1
As an index. Here, the index 100 was 18700 km.

[0023]

As described above, according to the present invention, it is possible to effectively suppress the separation in the vicinity of the widthwise outer end of the widest reinforcing ply while suppressing the radial growth of the tread portion.

[Brief description of the drawings]

FIG. 1 is a meridional section of a tire showing one embodiment of the present invention.

FIG. 2 is a partially broken plan view of a tread portion.

[Explanation of symbols]

11 ... pneumatic tire 12 ... bead 18 ... carcass layer 24 ... belt layer 25 ... belt ply 25a ... widest belt ply 26 ... reinforcement cord 28 ... tread rubber 31 ... belt reinforcement layer 32 ... reinforcement ply 32a, b ... widest width reinforcement Ply 33 ... Reinforcing element 34 ... Outside edge in width direction 35 ... Outside edge in width direction

Claims (6)

[Claims] 1. A carcass layer extending in a toroidal shape between beads, and at least two reinforcing cords disposed radially outside of the carcass layer and sloping in a direction opposite to the tire equatorial plane S are embedded. A belt layer composed of a belt ply, a belt reinforcement layer composed of at least one reinforcement ply in which a reinforcement element that is arranged to overlap the belt layer and that extends in the circumferential direction while being bent in a wavy or zigzag shape is embedded therein; Layer and a tread rubber disposed radially outside of the belt reinforcing layer, the widthwise outer end of the widest widest reinforcing ply having the widest width is outside the widest belt ply having the widest width. A pneumatic tire, wherein the pneumatic tire is disposed outward in a width direction from an end. 2. When the maximum carcass width of the carcass layer is L, a point P at which the widthwise outer end of the widest reinforcing ply is 0.375 times the maximum carcass width L outward from the tire equatorial plane S in the width direction. Point Q separated by 0.45 times the maximum width L of the carcass
The pneumatic tire according to claim 1, wherein the pneumatic tire is positioned between the tire and the tire. 3. Assuming that the width of the widest belt ply is N, a point U at which the widthwise outer end of the widest reinforcement ply is separated from the widthwise outer end of the widest belt ply by 0.05 times the width N. The pneumatic tire according to claim 1 or 2, further positioned outside in the width direction. 4. The pneumatic tire according to claim 1, wherein the belt reinforcing layer is disposed radially inside the belt layer. 5. The pneumatic tire according to claim 1, wherein the belt reinforcing layer is disposed between belt plies constituting the belt layer. 6. The pneumatic tire according to claim 1, wherein the belt reinforcing layer is disposed radially outside the belt layer.