JPH09207513A - Air-filled radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air-filled radial tire which improves straight advancing stability on a sloped road surface of a rut or the like by suppressing wondering. SOLUTION: In an air-filled radial tire 1, a belt layer 3 and a tread 4 are successively arranged in the periphery of a crown part of a carcass layer 2 astride in a toroidal shape between a pair of bead cores, a rubber layer 6 having a thickness larger than a tire radial direction thickness of a belt is arranged in a position including a tire equator surface M, the belt layer 3 has a width direction sectional shape protrusive in a tire diametric direction outer side, in the vicinity of a shoulder side end part of the belt layer 3 or in the vicinity of an end part of the rubber layer 6, at least a sheet of 160kgf/mm<2> or more elastic modulus or at least two sheets of 120kgf/mm<2> or more elastic modulus reinforced layers 7, having a width 0.1 to 0.3 times the width of a belt in the broadest width, are arranged, a groove 5 substantially extended in a tire peripheral direction is arranged in the corresponding tread 4 in the vicinity of the end part of the rubber layer 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention suppresses a complicated movement of a vehicle that is unpredictable by a driver, that is, so-called wandering, which occurs when a vehicle travels on a road surface having an inclined portion, for example, a road surface having unevenness such as a rut. The present invention relates to a pneumatic radial tire having improved straight running stability, particularly to a light truck tire and a light truck tire, a truck and bus tire.

[0002]

2. Description of the Related Art In recent years, not only passenger cars but also vehicles such as light trucks, light trucks, trucks and buses, so-called radial tires in which carcass cords are arranged in a direction substantially perpendicular to the tire equatorial plane are bias tires. It has been widely used because it is superior in wear resistance and steering stability compared to.

[0003]

With the increase in speed of vehicles, the adoption of radial tires has increased.
As vehicles have become routinely driven at high speeds due to the expansion and improvement of the road network, the occurrence of the wandering problem has increased. Since this wandering is a dangerous phenomenon that impairs the straight running stability of the vehicle, it has become a serious problem as the performance of tires is improved.

Therefore, an object of the present invention is to propose a pneumatic radial tire which suppresses wandering and improves straight running stability on a sloped road surface such as a rut.

[0005]

Means for Solving the Problems A belt layer and a tread are sequentially arranged on the outer circumference of a crown portion of a carcass layer straddling in a toroidal shape between a pair of bead cores, and the belt layer is a stack of at least two belts. A rubber layer having a thickness greater than the tire radial thickness of the belt is disposed at a position including the tire equatorial plane, and the belt layer has a widthwise sectional shape that is convex outward in the tire radial direction, Near the end of the belt layer on the shoulder side, the width of the widest belt is 0.1
A pneumatic radial tire characterized in that at least one reinforcing layer having an elastic modulus of 160 kgf / mm ² or more having a width of ˜0.3 times is arranged.

When a tire tries to cross an inclined road surface such as a rut or the like in a direction in which the tire rides up with an approach angle, as shown in FIG. 4, a reaction force FR from the road surface occurs on the tire and the inclined road surface. Lateral force F due to camber thrust FC
y works. Here, when the tire is made to be radial, the rigidity of the tire becomes high, and the reaction force F is higher than that of the bias tire.
Since R is large and the camber thrust FC is small, the lateral force Fy is also large, which makes it impossible to smoothly run over the rut and it was found that wandering occurs. Therefore, in order to suppress the wandering in the radial tire, the lateral force Fy can be increased by increasing the camber thrust FC.
It is effective to reduce

The camber thrust FC is generated by the bending deformation in the tire cross section of the tread when the tire is grounded on the inclined road surface and is flexibly deformed. That is, as shown in FIG. 5, the tread bending deformation bS near the tread ground contact end
It can be considered as the resultant force of the lateral force FCS generated by the above and the lateral force FCC generated by the tread bending deformation bc near the tire equatorial plane. Therefore, to increase the camber thrust FC, it is sufficient to increase the FCS and decrease the lateral force FCC.

According to the present invention, since the belt layer has a cross-sectional shape in the width direction that is convex outward in the radial direction of the tire, the bending deformation bs of the tread that tends to become flat with ground contact increases, and as a result, the tread ground contact end. Lateral force F generated near the section
CS can be increased. In order to have the convex widthwise cross-sectional shape, the rubber layer having a thickness greater than the tire radial direction thickness of the belt at a position including the tire equatorial plane has a width of the widest belt layer as BW, 0.1
It is preferably in the range of 5 × BW to 0.50 × BW, and the thickness thereof is usually 1 to 5 mm at least on the tire equatorial plane.

At least one reinforcing layer having a width of 0.1 to 0.3 times the width of the widest belt and an elastic modulus of 160 kgf / mm ² or more near the shoulder side end of the belt layer, or ^Two or more reinforcing layers having an elastic modulus of 120 kgf / mm ² or more are arranged. Therefore, in the belt end area,
Great rigidity is obtained by the truss effect of the two belt layers and the reinforcing layer. The elastic modulus here is the stress when a tensile strain of 1% is applied. Therefore, by disposing the reinforcing layer, the convex shape at the time of internal pressure filling can be further strengthened and the belt rigidity of the portion can be increased, so that the bending deformation bS of the tread can be significantly increased. . Here, the elastic modulus of at least one reinforcing layer arranged near the shoulder side end of the belt layer is 160 kgf / mm.
^An elastic modulus of less than ² or even with two or more reinforcing layers
If it is less than 20 kgf / mm ² , sufficient rigidity cannot be ensured in the belt end region, so a sufficient improvement effect cannot be expected. In addition, the reason why the width of the widest belt is 0.1 to 0.3 times the width is that if the width is less than 0.1 times, the rigidity of the convex shape and the belt end area cannot be sufficiently strengthened, and the width is 0.3 times. If it is larger, the bending deformation bS is improved, but the convex shape cannot be strengthened, and in any case, a sufficient improvement effect due to the arrangement of the reinforcing layer cannot be obtained. Further, the reinforcing layer can be expected to improve the bending deformation bS regardless of whether the reinforcing layer is arranged on the outer side in the radial direction of the belt layer, inside the belt layer, or on the inner side in the radial direction of the belt layer, but since the convex shape is further strengthened. It is preferable to arrange it on the outer side in the radial direction of the belt layer. From the above, while maintaining the rigidity of the entire belt moderately, the mutual binding force between the belt layers is relatively weak in the vicinity of the equatorial plane of the tire, and the mutual binding force between the belt layers in the other belt end regions is It becomes possible to increase the strength, and the lateral force FCC generated in the tread can be reduced. The reinforcing layer here is made of an organic fiber such as nylon or polyethylene terephthalate.

By arranging a groove extending substantially in the tire circumferential direction in the tread corresponding to the vicinity of the end portion of the rubber layer, the bending deformation bS of the tread becomes larger and occurs near the tread ground contact end portion. Lateral force FCS can be further increased. Further, at the time of vulcanization molding, the groove can prevent the rubber layer from flowing outward in the width direction, and the convex shape can be further strengthened.

[0011]

DETAILED DESCRIPTION OF THE INVENTION Size according to the structure shown in FIG.
195 / 85R16 114 / 112LT pneumatic radial tire 1 for small trucks was prototyped according to the specifications in Table 1 by changing the groove layout. In FIG. 1, the reinforcing layer 7 is composed of three rubber-coated plies having a large number of polyester cords arranged in the radial direction.
And tread 4 are placed. Carcass 2 consists of 1 sheet. Further, the belt 3 is composed of two steel belts and is adjacent to the carcass and has a relatively small inclination angle of the cord with respect to the tire equatorial plane 3-1 (hereinafter, also referred to as the first belt), 3-2 Two cords (hereinafter, also referred to as a second belt) are laminated so that the cords intersect each other with the tire equatorial plane in between.

[0012]

EXAMPLES Examples will be shown below. The first belt has a cord inclination angle of 24 ° and a width of 120 mm, and the second belt has a cord inclination angle of 24 ° and a width of 105 mm. Of these two belts, the widest belt is the first belt. , This width is BW. The tread is provided with four grooves 5 extending substantially continuously in the tire circumferential direction. Illustration of the vicinity of the bead core is omitted.

Example 1 As shown in FIG. 1, by arranging the rubber layer 6 between the carcass 2 and the first belt 3-1 at a position including the tire equatorial plane M, the belt is moved to the center of the tread. The portion has a width-direction cross-sectional shape that is convex outward in the tire radial direction. Here, in the prototype tire, the width center of the rubber layer 6 was arranged so as to substantially coincide with the tire equatorial plane M. The width of the rubber layer was 50 mm, corresponding to 0.37 × BW, and the thickness was 3 mm. In addition, since the rubber layer 6 has a substantially rectangular cross section,
Further, the second belt ply has a stepped shape in the width direction, which is convex outward in the tire radial direction. However, the cross-sectional shape of the rubber layer 6 is not limited to this, and may be, for example, a convex lens cross-sectional shape. When the convex lens has a cross-sectional shape, a wandering suppressing effect can be expected especially when the vehicle is empty or when the camber angle is small. The elastic modulus of 1 having a width 0.17 times the width of the widest belt near the shoulder side end of the belt layer.
One reinforcing layer of 79 kgf / mm ² has a distance a of 35 from the tire equatorial plane to the inner side of the reinforcing layer in the axial direction of the tire as shown in FIG.
It is arranged at a position of mm. Here, the circumferential groove depth is
9.5 mm near the equatorial plane of the tire and 12 mm near the ground contact edge.
In addition, the groove 5-1 on the tire equatorial side is 16 from the tire equatorial side.
There is shown an example in which the rubber layer 6 is arranged on a tread corresponding to the vicinity of the end of the rubber layer 6 at a distance of mm, but such an arrangement is more effective in suppressing wandering.

Example 2 In Example 2, the elastic modulus 139 having a width 0.17 times the width of the widest belt near the shoulder side end of the belt layer.
Two reinforcing layers of kgf / mm ² or more are arranged.

Example 3 Example 3 is substantially the same as Example 2 except that the groove 5-1 on the tire equatorial plane side is located at a distance of 25 mm from the tire equatorial plane.

Example 4 Example 4 is substantially the same as Example 2 except that the distance a from the equatorial plane of the tire to the inner side of the reinforcing layer in the axial direction of the tire is 20 mm.

Conventional Example As a conventional example, a tire of the above size having the structure shown in FIG. 3 was prepared. The difference from the first embodiment is that the carcass is 2
The end of the folded-back part is located inside the tire maximum width in the tire radial direction.Because of the absence of the rubber layer 6, the belt is located radially outside in the tire tread center part compared to the carcass 2 shape. That is, it does not have a convex cross-sectional shape in the width direction.

After filling these tires with a specified internal pressure of 6.0 kgf / cm ² , a small truck of 2 tons loading (rear wheel is a double-wheel type)
The test driver was run on a paved road including a rut in a state where the specified maximum load was applied to the small truck, and straight running stability was sensory evaluated. The results are also shown in Table 1 in the index evaluation with the conventional example being 100 (the larger the index, the better). From the table, it is clear that the straight running stability of the tire according to the present invention is remarkably improved.

[0019]

[Table 1]

That is, according to the present invention, it is possible to suppress the wandering of the pneumatic radial tire and improve the straight running stability on an inclined road surface such as a rutted road.

[Brief description of drawings]

FIG. 1 is a tire width direction sectional view of a pneumatic radial tire according to the present invention.

FIG. 2 is a sectional view in the tire width direction of the pneumatic radial tire according to the present invention.

FIG. 3 is a sectional view in the tire width direction of a conventional example.

FIG. 4 is a schematic view showing a state in which a tire is in contact with a sloped road surface.

FIG. 5 is a schematic diagram showing deformation and lateral force when a tire is in contact with a sloped road surface.

[Explanation of symbols]

 1 Pneumatic radial tire 2 Carcass 3 Belt 4 Tread 5 Groove 6 Rubber layer 7 Reinforcement layer M Tire equatorial plane

Claims (4)

[Claims] 1. A belt layer and a tread are sequentially arranged on the outer periphery of a crown portion of a carcass layer straddling in a toroidal shape between a pair of bead cores, and the belt layer is formed by laminating at least two belts. A rubber layer having a thickness greater than the tire radial direction thickness of the belt is arranged at a position including the tire equatorial plane between the carcass layer and the belt layer, and the belt layer has a width direction convex outward in the tire radial direction. At least one elastic fiber made of organic fibers having a cross-sectional shape and having a width of 0.1 to 0.3 times the width of the widest belt near the end of the belt layer and having an elastic modulus of 160 kgf / mm ² or more. A pneumatic radial tire having a reinforcing layer. 2. A belt layer and a tread are sequentially arranged on the outer circumference of a crown portion of a carcass layer straddling in a toroidal shape between a pair of bead cores, and the belt layer is formed by laminating at least two belts. A rubber layer having a thickness greater than the tire radial direction thickness of the belt is arranged at a position including the tire equatorial plane between the carcass layer and the belt layer, and the belt layer has a width direction convex outward in the tire radial direction. At least one elastic member made of an organic fiber having a cross-sectional shape and having a width of 0.1 to 0.3 times the width of the widest belt near the end of the rubber layer and having an elastic modulus of 160 kgf / mm ² or more. A pneumatic radial tire having a reinforcing layer. 3. The pneumatic radial tire according to claim 1, wherein the reinforcing layer is provided with at least two reinforcing layers made of organic fibers having an elastic modulus of 120 kgf / mm ² or more. 4. The pneumatic radial tire according to claim 1, wherein a groove substantially extending in the tire circumferential direction is arranged in a tread corresponding to an end portion of the rubber layer.