JP2003231403A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress both abnormal wear near a tread end 35 and a separation at the end of a belt. <P>SOLUTION: A part of a divided reinforcement layer 36 having a considerable degree of circumferential shearing rigidity is presented by burying tilted reinforcement elements in a tire on the lateral outside of a tilted belt layer 24 and a reinforced belt layer 31 to suppress a shearing deformation near the tread end 35. The divided reinforcement layer 36 is partially overlapped with tilted ply 25 to provide a considerable degree of freedom to the divided reinforcement layer 36. Thus the deformation of the divided reinforcement layer 36 occurring at the lateral outside end 36a can be reduced. <P>COPYRIGHT: (C)2003,JPO

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 layer is composed of an inclined belt layer having an inclined reinforcing element embedded therein and a reinforcing belt layer having a circumferential reinforcing element embedded therein.

[0002]

2. Description of the Related Art Generally, the outer surface of a tread portion of a pneumatic tire is relieved from the fact that the contact pressure near the tread end is increased due to the influence of the rigidity of the sidewall portion, and the contact shape and the distribution of the contact pressure are properly adjusted. In order to hold at, it is composed of an arc with a single radius of curvature or multiple arcs with different radii of curvature, and is formed in a convex shape so that the radius (distance from the rotation axis) increases from both tread ends toward the tire equatorial plane. Has been done.

When the outer surface of the tread portion is formed in a convex shape as described above, the circumferential length in the vicinity of the tire equatorial plane becomes longer than the circumferential length in the vicinity of the tread end due to the aforementioned diameter difference. Due to the difference in circumference, the force toward the front (driving side) in the traveling direction is near the equatorial plane of the tire when rolling, while it is rearward (braking side) in the traveling direction near the tread end.
Is generated on the outer surface of the tread portion in contact with the road surface, which causes the tread rubber to move in the ground contact surface as shown in FIG.
Shear deformation as shown in.

When the shear deformation is performed in this manner, a force that balances the force generated inside the tread rubber is generated on the surface of the tread portion. This force is a force toward the driving side in the vicinity of the equatorial plane of the tire as described above. On the other hand, in the vicinity of the tread end, the force is toward the braking side. Since the force toward the braking side causes the tread rubber to wear earlier than the force toward the driving side, the area near the tread edge is worn more than the area near the tire equatorial plane, and in particular, the pneumatic tire is mounted on the driven wheel of the vehicle. In that case, the above-mentioned wear becomes more remarkable because the force toward the braking side becomes larger.

[0005]

SUMMARY OF THE INVENTION Here, in order to make the diameter growth distribution of the tread portion uniform while suppressing the belt end separation due to the flattening of the tire (oblateness ratio of 0.70 or less) in recent years, JP-A-2000-2000 has been proposed. As disclosed in JP-A-203215, there is proposed a pneumatic tire in which a width of a reinforcing belt layer in which a reinforcing element extends in a circumferential direction is wider than a width of an inclined belt layer in which the reinforcing element is inclined with respect to a tire equatorial plane. However, in such a pneumatic tire, the above-mentioned diameter difference is large, and further, since the reinforcing element extends in the circumferential direction in the vicinity of the tread end, the circumferential shear rigidity has a small value. Since there is only the widthwise outer end portion of the reinforced belt layer, the shear deformation amount of the tread rubber near the tread edge becomes large, and as a result, wear near the tread edge is further increased. There is a problem that uneven wear is generated due to the accelerated running for a long time.

In order to solve such a problem, it is conceivable to make the width of the inclined belt layer wider than the width of the reinforced belt layer, contrary to the pneumatic tire of the above-mentioned publication. There is a problem that strain is concentrated at the widthwise outer end of the inclined belt layer during load rolling of the pneumatic tire, and belt end separation occurs at the widthwise outer end of the inclined belt layer.

An object of the present invention is to provide a pneumatic tire capable of suppressing both abnormal wear near the tread edge and belt edge separation.

[0008]

The object is to provide a carcass layer extending between the beads in a substantially toroidal shape, a belt layer arranged radially outside the carcass layer, and a belt layer radially outside the belt layer. And a tread rubber, the belt layer is arranged so as to overlap the inclined belt layer and an inclined belt layer formed of at least two inclined plies in which reinforcing elements inclined with respect to the tire equatorial plane S are embedded, A pneumatic tire composed of a reinforced belt layer made of at least one reinforced ply in which a reinforcing element extending substantially in the circumferential direction is embedded, wherein a widthwise inner side is provided at both widthwise outer ends of one of the inclined plies. The ends overlap each other in the radial direction while closely contacting each other, and the outer ends in the width direction are positioned outward in the width direction from the outer ends in the width direction of any of the plies, and the plies are closely contacted inside. That inclined plies and reinforcing elements inclined in the same direction can be achieved by providing a pair of divided reinforcing layer made of buried split ply.

As described above, the widthwise inner ends of the inclined plies overlap each other in the widthwise direction while being in close contact with the widthwise outer ends thereof, and the widthwise outer ends thereof are wider than the widthwise outer ends of the plies. Since a pair of split reinforcing layers located outside in the direction is provided, a part of the split reinforcing layers always exists on the outer side in the width direction than the inclined belt layer and the reinforced belt layer. Since the reinforcing element that is inclined in the same direction as the inclined ply is embedded inside the ply, the shear strength in the circumferential direction of the divided reinforcing layer becomes larger than that of the reinforced belt layer.

As a result, the shearing deformation of the tread rubber near the tread edge due to the difference in circumferential length as described above is suppressed by the split reinforcing layer, whereby the braking side near the tread edge due to the shearing deformation is suppressed. The force directed to is reduced, and uneven wear can be effectively suppressed.

Further, as described above, when the widthwise outer end of each of the split reinforcing layers is positioned outside the widthwise outer end of any of the plies, the widthwise outer end of the split reinforcing layer is distorted during load rolling. Is thought to be concentrated, but the divided reinforcing layer is
The width is narrower than the slant ply, and the widthwise inner edge of the slant ply overlaps both outer edges of the slant ply in the width direction. can do.

As a result, the strain generated at the widthwise outer end of the divided reinforcing layer does not have a large value, and the belt end separation is suppressed at that portion. Here, when the reinforcing element embedded inside the divided reinforcing layer is tilted in the direction opposite to the reinforcing element of the slanting ply that is in close contact, the rigidity of these close contacting parts is increased and interlayer separation occurs. However, in the present invention, the situation in which the rigidity is increased is prevented by inclining in the same direction.

Further, according to the second aspect, since the width of the split reinforcing layer itself can be narrowed,
Belt end separation at the widthwise outer end of the split reinforcing layer can be effectively suppressed. Further, according to the third aspect, the separation between the split reinforcing layer and the inclined ply can be effectively suppressed.

Further, according to the present invention, the separation between the split reinforcing layer and the inclined ply is effectively suppressed, while the shear deformation of the tread rubber near the tread edge is effectively suppressed. can do. Furthermore, according to the fifth aspect, it is possible to effectively suppress the strain concentration at the widthwise outer ends of the split reinforcing layer and the inclined ply.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below with reference to the drawings. In FIGS. 1 and 2, 11 is a flat heavy-duty pneumatic radial tire with a flatness ratio of 0.70 or less, which is mounted on a truck, a bus, etc. The pneumatic tire 11 has a pair of bead portions in which beads 12 are embedded.
13, a sidewall portion 14 extending from the bead portion 13 toward the outer side in the substantially radial direction, and a substantially cylindrical tread portion 15 connecting outer ends of the sidewall portion 14 in the radial direction.

The pneumatic tire 11 extends in a substantially toroidal shape between the beads 12 and has a sidewall portion 14,
A carcass layer 18 for reinforcing the tread portion 15 is provided, and both ends of the carcass layer 18 are folded back around the bead 12 from the axially inner side toward the axially outer side. The carcass layer 18 comprises at least one, here one carcass ply 19, in which the non-stretchable reinforcing element 20, e.g. steel cord, extends substantially in the radial direction (meridian direction). Many are buried. A chafer 21 reinforced by, for example, a steel cord is arranged around the carcass layer 18 in the bead portion 13.

Reference numeral 24 denotes an inclined belt layer arranged on the outer side in the radial direction of the carcass layer 18. The inclined belt layer 24 is constituted by laminating at least two (here, two) inclined plies 25, and A large number of non-stretchable reinforcing elements 26 made of, for example, steel or aramid fiber are embedded inside the inclined ply 25. The reinforcing element 26 embedded in the inclined ply 25 is 10 to 10 with respect to the tire equatorial plane S.
The inclination angle G is 60 degrees, preferably 40 to 60 degrees, and the inclination direction of the at least two inclination plies 25 with respect to the tire equatorial plane S is opposite.

Here, the inner inclined ply 25a located on the radially inner side is wider than the outer inclined ply 25b located on the radially outer side. As a result, in this embodiment, the inner inclined ply 25a is The widest inclined ply.
28 is a tread rubber arranged on the outer side in the radial direction of the carcass layer 18 and the inclined belt layer 24, and 29 is a side rubber arranged on the both outer sides in the axial direction of the carcass layer 18.

Reference numeral 31 denotes a reinforcing belt layer which is arranged radially inward of the inclined belt layer 24 and radially outward of the carcass layer 18, that is, between the inclined belt layer 24 and the carcass layer 18 so as to overlap the inclined belt layer 24. And the reinforced belt layer 31 is at least one, here two reinforced plies 32 laminated together.
It consists of

Inside each reinforcing ply 32, a reinforcing element 33 extending substantially in the circumferential direction and made of steel, aramid fiber or the like is embedded, and the reinforcing element 33 is made of a cord (stranded wire) or a monofilament. At the same time, a large number of reinforced plies 32 appear on the meridional section. The reinforcing element 33 is bent in a wave shape or a zigzag shape in a plane parallel to the front and back surfaces of the reinforcing ply 32, for example, a square wave, a triangular wave, or a sine wave.

Each reinforcing ply 32 is constructed, for example, by winding a plurality of reinforcing elements 33 in a line and a rubber-coated ribbon-like body on the outside of the carcass layer 18 in a spiral manner. The tilted belt layer 24 and the reinforced belt layer 31 described above are arranged as a whole on the outer side in the radial direction of the carcass layer 18, and a plurality of tilted plies 2 in which the reinforcing elements 26 and 33 are embedded.
5. The belt layer 34 including the reinforcing ply 32 is formed.

Here, both reinforcing plies 32 have the same width and are wider than the widest inner slant ply 25a described above, and as a result, the widthwise outer ends of both stiffening plies 32 are inner slant plies. It is located outside the width direction of 25a. Here, since the reinforcing element 33 in the reinforcing ply 32 extends substantially in the circumferential direction and hardly resists the circumferential shearing, the widthwise outer ends of the reinforcing ply 32, that is, in the vicinity of the tread end 35. The circumferential shear rigidity has a considerably small value.

However, in this embodiment,
The widthwise inner ends are in close contact with the widthwise outer ends of the inner slant ply 25a and are radially outwardly overlapped.
32) and a pair of split reinforcing layers 36 located outside in the width direction from the outer ends in the width direction, and each split reinforcing layer 36 is in the same direction as the inner inclined ply 25a that is closely adhered to the inside. It is composed of at least one (in this embodiment, one) split ply 38 in which a reinforcing element 37 inclined to the inside is embedded.

As a result, a part of the split reinforcing layer 36 is always present outside the widthwise outer ends of the inclined belt layer 24 and the reinforcing belt layer 31, but the split reinforcing layer 36 is formed. Since the inclined reinforcing element 37 that resists the circumferential shear to some extent is embedded inside the split ply 38, the circumferential shear rigidity of the split reinforcing layer 36 is the reinforcing belt layer 31.
It becomes a large value compared to both outer ends in the width direction.

As a result, the shearing deformation of the tread rubber 28 near the tread edge 35 due to the difference in circumferential length as described above is suppressed by the split reinforcing layer 36, whereby the shearing deformation near the tread edge 35 is caused. The force directed toward the braking side at is reduced, and uneven wear is effectively suppressed.

Further, as described above, if the widthwise outer end 36a of the split reinforcing layer 36 is positioned further outward than the widthwise outer ends of the reinforced plies 25 and 32 by any inclination, the split reinforcing layer 36 will be split when the load rolls. Although it is considered that the strain is concentrated on the widthwise outer end 36a of the reinforcing layer 36, the divided reinforcing layer 36 is narrower than the widest inner slant ply 25a, and the inner end in the width direction thereof is an inner slant ply. Since the outer edges of the width direction 25a are overlapped with each other, they can be deformed more freely than the inclined belt layer 24 while receiving some restraint from the inclined belt layer 24.

As a result, the widthwise outer end 36 of the split reinforcing layer 36
The strain generated in a does not take a large value, and the belt end separation is suppressed from occurring at the portion.
Here, the reinforcing element 37 embedded inside the divided reinforcing layer 36 is attached to the reinforcing element of the inner inclined ply 25a which is in close contact.
If it is tilted in the opposite direction to 26, the rigidity of these contact parts may increase and interlayer separation may occur, but in this embodiment, the reinforcing elements 37 and 26 are tilted in the same direction as described above. The layer separation is suppressed by preventing a situation where the rigidity becomes high.

Further, as described above, the divided reinforcing layer 36 is provided in the inner inclined ply having the widest width among the plurality of inclined plies 25.
By arranging the split reinforcing layer 36 in close contact with each other, the width of the split reinforcing layer 36 itself can be narrowed, so that the belt end separation at the widthwise outer end 36a of the split reinforcing layer 36 can be effectively suppressed.

Here, the split ply 38 of the split reinforcing layer 36.
The reinforcing element 37 embedded in the same as the reinforcing element 26 in the inclined ply 25 is made of a non-stretchable material such as steel or aramid fiber. The reinforcing element 37 of the divided reinforcing layer 36 is parallel to the reinforcing element 26 embedded in the inner inclined ply 25a with which the divided reinforcing layer 36 is in close contact,
Alternatively, it is preferable that the intersections are within the range of +10 degrees to −10 degrees. Here, + means the direction in which the inclination angle with respect to the tire equatorial plane S becomes large.

The reason is that when the crossing angle K exceeds +10 degrees or -10 degrees, the split ply 38 and the inner inclined ply 25
There is a possibility that interlayer strain will concentrate in the area where it adheres to a,
As described above, when the layers are parallel or in the range of +10 degrees to −10 degrees, such concentration of interlayer strain can be relaxed.

The width L of the contact portion between the split reinforcing layer 36 (split ply 38) and the inner inclined ply 25a is tread width W.
It is preferable to set it within the range of 0.03 to 0.10 times. The reason is that if the value of L / W is less than 0.03, the inner inclined ply is
The split reinforcing layer 36 may not be restrained sufficiently by 25a to effectively suppress the shear deformation of the tread rubber 28 in the vicinity of the tread edge 35. On the other hand, when it exceeds 0.10, the split reinforcing layer 36 and Distortion may be concentrated between the inner inclined ply 25a and the separation, which may cause separation. However, if it is within the above range, such separation between the divided reinforcing layer 36 and the inner inclined ply 25a is effectively suppressed. However, shear deformation of the tread rubber 28 near the tread edge 35 can be effectively suppressed.

Further, it is preferable that the width M of the inclined ply, in this case the inner inclined ply 25a to which the split reinforcing layer 36 is in close contact, be 0.40 to 0.85 times the tread width W. The reason is that when the value of M / W is less than 0.40, the width of the split reinforcing layer 36 becomes wider and the strain is concentrated on the widthwise outer end 36a, while when it exceeds 0.85, the inclined ply, here. Although the strain may be concentrated on the widthwise outer end of the inner inclined ply 25a to cause separation, if it is within the above range, the strain concentration at the widthwise outer end of the split reinforcing layer 36 and the inner inclined ply 25a is effective. It can be suppressed.

FIG. 3 is a diagram showing a second embodiment of the present invention. In this embodiment, the inner ends in the width direction of the split reinforcing layer 36 are superposed on the inner sides in the radial direction while being in close contact with both outer ends in the width direction of the inner sloped ply 25a having the widest width. Even in this case, it is possible to obtain substantially the same effect as that of the first embodiment. The other configurations and operations are the same as those in the first embodiment.

FIG. 4 is a diagram showing a third embodiment of the present invention. In this embodiment, the width of the inner inclined ply 25a, which is the widest, and the width of both the reinforcing plies 32 are opposite to those of the first embodiment, and the former is wider than the latter.
In the case of this embodiment, the widthwise outer end of the inner inclined ply 25a is covered with the split reinforcing layer 36 which is deformable to some extent, so that the separation at these ply ends is effectively suppressed. be able to. The other configurations and operations are the same as those in the first embodiment.

In the above-described embodiment, the inner reinforcing ply 25a having the widest width is superposed on the divided reinforcing layer 36 while being in close contact with each other.
You may make it overlap | superpose, making a division | segmentation reinforcement layer contact | adhere to the inclination ply narrower than the widest inclination ply.

Further, in the above-mentioned embodiment, the reinforcing belt layer 31 is arranged on the inner side in the radial direction of the inclined belt layer 24. However, in the present invention, the reinforcing belt layer is arranged between the inclined plies constituting the inclined belt layer. You may choose to
Further, the reinforcing belt layer may be arranged on the outer side in the radial direction of the inclined belt layer. Here, in the case of the latter, since the reinforcing element in the reinforcing ply extending substantially in the circumferential direction may be cut by the projection input, the protective layer may be arranged on the outer side in the radial direction of the reinforcing belt layer. preferable.

[0037]

EXAMPLES Next, test examples will be described. In this test, the conventional tire in which the split reinforcing layer was omitted from the pneumatic tire described in the first embodiment, and the inner inclined ply of the conventional tire were widened, and both reinforcing plies were narrowed. A comparative tire in which the inner inclined ply is wider than both the reinforcing plies (the split reinforcing layer is omitted), and a reinforcing element in the inner inclined ply and a reinforcing element in the split reinforcing layer having the same configuration as in the first embodiment. Of the embodiment tires 1 to 7 different from each other only in the intersection angle K, and the execution tires 8 to 13 different from the execution tire 1 only in the value of the ratio L / W of the width L of the contact portion and the tread width W, and the inner inclined ply. Implementation tires 14 to 19 that differ from the implementation tire 1 only in the value of the ratio M / W between the width M and the tread width W, an implementation tire 20 having the same configuration as the second embodiment, and the same as the third embodiment. Implementation of configuration It was prepared and the ear 21.

Here, the size of each tire is 435 /
45R22.5, tread width W is 390 mm, and the inclination angle G of the reinforcing element in the inclined ply with respect to the tire equatorial plane S is 52 degrees.
In addition, the distance between the outer ends in the width direction of both the split reinforcing layers in the practical tires 1 to 21 is 400 mm (the same as the inner inclined ply width of the comparative tire). Other specifications of each tire, namely,
The intersection angle K (degree) between the reinforcing element in the inner inclined ply and the reinforcing element in the divided reinforcing layer, the ratio L / W of the contact portion width L and the tread width W, the width M of the inner inclined ply and the tread width W The values of the ratio M / W of are shown in Tables 1 and 2 below.

Next, each of such tires is tested with 14.00 × 22.5
The rim-assembled tire was mounted on the driving wheel of a 2-D shaft type large-sized bus after being mounted on the rim of the vehicle and being filled with an internal pressure of 900 kPa. After that, the tires were driven at a speed of 80 km / h on an expressway for 10,000 km while applying a load of 49.0 kN to the tires, and the wear amount on the equatorial plane S and the wear amount near the tread end were measured. Then, the wear amount difference C (mm) was obtained.

At this time, the tread rubber of each tire was peeled off, and the crack length N at the widthwise outer end of the ply was measured.
(Mm) was measured. Here, the ply at which the maximum crack occurs varies depending on the tire, but the crack length N is a measured value of the maximum crack. The results are shown in Tables 1 and 2 below. Here, the smaller the wear amount difference C, the better the uneven wear resistance and the crack length N.
The smaller the value of, the better the separation resistance (durability).

[0041]

[Table 1]

[0042]

[Table 2]

From Tables 1 and 2 above, in the practical tires 1 to 20, it is possible to improve the uneven wear resistance while substantially maintaining the separation resistance as compared with the conventional tire. It can be understood that, compared with the comparative tire, the separation resistance is improved while substantially maintaining the uneven wear resistance.

Further, from the results of the practical tires 1 to 7, when the value of the intersection angle K is within the range of +10 degrees to -10 degrees, cracking can be effectively suppressed, but the range of the above values When it is outside, the effect of suppressing the occurrence of cracks becomes insufficient, and from the results of the implemented tires 8 to 13, the L / W value is 0.03.
When it is within the range of 0.10, the uneven wear resistance can be effectively improved while effectively suppressing the crack generation, but when it is out of the range of the above value, the crack generation is suppressed and the uneven wear resistance is suppressed. It can be understood that the effect of improving the sex is not sufficient. Further, from the results of the practical tires 14 to 19, when the value of M / W is within the range of 0.40 to 0.85, it is possible to effectively suppress the occurrence of cracks. It can be understood that the suppression effect is not sufficient.

[0045]

As described above, according to the present invention, both abnormal wear and belt edge separation near the tread edge can be suppressed.

[Brief description of drawings]

FIG. 1 is a meridian sectional view of a tire showing a first embodiment of the present invention.

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

FIG. 3 is a meridian sectional view of a tire showing a second embodiment of the present invention.

FIG. 4 is a meridian sectional view of a tire showing a third embodiment of the present invention.

FIG. 5 is an explanatory diagram illustrating a deformed state of a tread portion within a ground contact surface.

[Explanation of symbols]

11 ... Pneumatic tire 12 ... Bead 18 ... Carcass layer 24 ... Slanted belt layer 25 ... Inclined ply 26 ... Reinforcing element 28 ... Tread rubber 31 ... Reinforced belt layer 32 ... Reinforcement ply 33 ... Reinforcing element 34 ... Belt layer 36 ... Divided reinforcement layer 36a ... Outer end in the width direction 37 ... Reinforcing element 38… Split ply

Claims (5)

[Claims] 1. A belt layer provided with a carcass layer extending between the beads in a substantially toroidal shape, a belt layer arranged radially outside the carcass layer, and a tread rubber arranged radially outside the belt layer. Is disposed so as to overlap the inclined belt layer and an inclined belt layer composed of at least two inclined plies in which a reinforcing element inclined with respect to the tire equatorial plane S is embedded, and the reinforcing element extending substantially in the circumferential direction inside. In a pneumatic tire composed of a reinforced belt layer composed of at least one reinforced ply in which is embedded,
The width-direction inner ends are in close contact with the width-direction outer ends of either of the inclined plies, and the width-direction outer ends are positioned outward of the width-direction outer ends of any of the plies. A pneumatic tire, characterized in that a pair of split reinforcing layers made of split plies in which reinforcing elements that are tilted in the same direction as the closely attached tilted plies are embedded are provided in the. 2. The pneumatic tire according to claim 1, wherein the split reinforcing layer is disposed in close contact with the widest widest inclined ply, which is the widest of the inclined plies. 3. The reinforcing element embedded in the divided reinforcing layer is parallel to or intersects with the reinforcing element embedded in the inclined ply in close contact with the reinforcing element in the range of +10 degrees to −10 degrees. Item 1. The pneumatic tire according to Item 1 or 2. 4. The pneumatic tire according to any one of claims 1 to 3, wherein a width L of a contact portion between the split reinforcing layer and the inclined ply is within a range of 0.03 to 0.10 times a tread width W. 5. The pneumatic tire according to claim 1, wherein a width M of the inclined ply with which the split reinforcing layer is in close contact is within a range of 0.40 to 0.85 times a tread width W.