JPH07149113A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve rectilinear running stability on an inclined road surface to control wandering by arranging the lateral central tread of a tread part so as to earth radially inside than a tread imaginary profile under the charge of specified inner pressure, and onto the road surface when a specific load is loaded. CONSTITUTION:A radial tire 1 is composed of two layers of belts 5 on the radial outside of the crown part 4 of a carcass 3, reinforcing layers 6,7 and a tread part 8. The tread 13 of a lateral central part 10 of the tread part 8 is arranged radially inside than a tread imaginary profile 16 and moreover the treads 14, 15 of lateral side parts 11, 12. In addition the tread 13 of the lateral central part 10 is composed so as to earth the road surface in a state where a specific load is loaded. Thus in a high performance tire having a reduced flatness rate, wandering on the road surface having an inclined part can be restrained, and rectilinear running stability can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention suppresses complicated movement of a tire, which is unpredictable by a driver, that is, so-called wandering, which occurs when a vehicle runs at high speed 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 tire having improved straight running stability.

[0002]

2. Description of the Related Art High-performance tires have a large lateral rigidity for generating a lateral force that can counter the centrifugal force generated when turning due to the increase in the output of a vehicle. Since it is required to have excellent braking performance, steering stability, etc., it has a tire shape with a low flatness ratio and a wide tire contact width.

[0003]

High-performance tires have excellent steering stability on a flat road surface, but when running at a high speed on a road surface having an inclined portion such as ruts on the ruts, the road surface shape is high. The non-uniform force corresponding to the unevenness of the part partially acts to cause a complicated behavior. For example, a tire having a reduced flatness ratio, particularly a tire for a passenger car having a flatness ratio of 60% or less, generally has a camber thrust received from the sloped road surface 23 when traveling on the sloped road surface 23 as shown in FIG. The effect of a large lateral force Fy resulting from Fc impairs the straight running stability.

That is, as shown in FIG. 5B, the tire is strongly pressed against the road surface 23 on the upper side 21 of the road surface by the applied load W, and the lower side 2 of the road surface 23.
At 2, the road surface 23 is lifted. Therefore, on the upper side 21 of the tire, due to the load W, the carcass ply collapses and deforms in the direction of the arrow due to the bending deformation of the side portion 24, and the belt 5 also bends and deforms in the direction of the arrow. Therefore, shear deformation occurs in the tread rubber. As a result, the tread rubber of the tire
A shearing force is generated in the direction of rising the road surface (arrow), and the resultant force of the shearing force on the entire ground contact surface becomes the canvas last Fc.

Therefore, when a force in the direction (arrow) for ascending the inclined road surface acts on the tire as described above, wandering occurs and the straight running stability of the vehicle is impaired.
It was necessary to develop means to prevent this wandering.

Therefore, an object of the present invention is to develop a pneumatic tire having improved straight running stability on the sloped road surface and suppressed wandering, particularly a high performance tire having a small flatness.

[0007]

According to the first aspect of the present invention, there is provided a pneumatic tire having a belt and a tread portion radially outside a crown portion of a carcass extending in a toroidal shape between a pair of beads. The widthwise central tread surface of the section is arranged radially inward of the tread virtual contour of the tread portion under the prescribed internal pressure filling, and further radially inwardly so as to contact the tread surface under a prescribed load. It is a pneumatic tire characterized by being arranged. Here, the virtual contour of the tread surface is a curve having a curvature of 1 or 2 that is convex outward in the radial direction such that the curvature is the smallest among the curves that are in contact with the tread surface in the lateral direction in the widthwise cross section of the tread portion. Is.

According to a second aspect of the present invention, in a pneumatic tire having a belt and a tread portion radially outside a crown portion of a carcass extending in a toroidal shape between a pair of beads, a tread surface in a width direction central portion of the tread portion is A pneumatic tire characterized by being divided by a plurality of lateral grooves or lateral sipes. Here, the lateral groove or lateral sipe may be inclined at least 30 ° with respect to the equatorial plane of the tire.

The central portion in the width direction of the tread portion, which is a feature of both of the above inventions, is 1 / th of the tread width in order to exert the effect.
3 is the maximum width and 1/10 of the tread width is the minimum width.

Further, in both of the above inventions, the widthwise central tread surface of the tread portion is separated from the widthwise lateral tread surface by the main groove extending in the circumferential direction at the tread portion, and the main groove faces the groove bottom. That the groove is a substantially inclined groove that approaches the tire equatorial plane, that a belt reinforcement layer having a narrow width is provided in the widthwise central portion of the tread portion, that the belt is arranged with its widthwise position unevenly distributed, It is preferable that the reinforcing layers are arranged such that their positions in the width direction are unevenly distributed.

[0011]

In the pneumatic tire of the first aspect of the invention, the tread surface at the center of the tread portion in the width direction is located radially inward of the virtual contour of the tread surface of the tread portion in a state where the tread surface has a prescribed air pressure, and
Further, when the specified load is applied, the road and the road surface are in contact with each other. Therefore, on the sloped road surface 23 as shown in FIG. 4, the belt and the tread portion located on the tread surface in the central portion in the width direction have a large deformation amount of the arrow. As a result, a force in the direction of descending the inclined road surface 23 (arrow) is applied to the tire, and the direction of rising the inclined road surface 23 (arrow indicated) is particularly remarkable in a high-performance tire having a small flatness. ) Has the effect of canceling the force.

In the pneumatic tire according to the second aspect of the invention, the tread surface in the widthwise central portion of the tread portion has a lateral groove or lateral sipe that divides into a plurality of blocks at intervals along the circumference thereof. The rigidity of the land portion in the compression direction due to the load in the widthwise central portion is reduced, and the belt and tread portion located on the tread surface in the widthwise central portion has a large amount of deformation in the arrow direction. It has a similar effect.

In each of the pneumatic tires of the first and second inventions, the main groove that divides the tread portion into the tread surface in the central portion in the width direction and the tread surface in the lateral direction in the width direction has a tire equator toward the groove bottom. In the inclined road surface 23 as shown in FIG. 4, since the land portion rigidity in the arrow direction is reduced in the widthwise central portion by having a substantial inclination close to the surface, the widthwise central portion tread surface of the inclined road surface during grounding. The falling-down deformation is likely to occur, and as a result, the camber thrust acting in the ascending road surface rising direction can be further reduced.

In the pneumatic tires of the first and second inventions, by embedding a narrow belt reinforcing layer in the widthwise central portion of the tread portion, the elongation of the belt in the widthwise central portion is suppressed and the tread. The central portion in the width direction of the portion is located further inward in the radial direction than the lateral side portions, and the deformation amount in the arrow direction becomes larger. Has the effect of canceling.

Further, the belt is arranged with its widthwise position unevenly distributed, and the belt reinforcing layer is arranged with its widthwise position unevenly distributed. By being unevenly distributed to the side wall portion located at, the diameter expansion due to the internal pressure filling of the portion reinforced by these is suppressed, so that the action of canceling the force in the direction of rising the sloped road surface 23 is further improved. be able to. The belt reinforcing layer here does not mean the belt reinforcing layer arranged in the widthwise central portion of the tread portion.

[0016]

FIG. 1 shows a typical cross section in the width direction of a pneumatic tire according to the first invention. As shown in this,
The pneumatic tire 1 includes a belt 5 formed by stacking two layers radially outside a crown portion 4 of a carcass 3 extending in a toroidal shape between a pair of beads 2, and a belt reinforcing layer 6 having a width equal to that of the belt. Is a radial tire including a narrow belt reinforcing layer 7 that covers an end portion of the wide belt reinforcing layer 6 and a tread portion 8. In the tread portion 8, 10 is a central portion in the width direction, and 11 and 12 are The width direction side part is shown.

In this tire, the tread surface 13 of the central portion 10 in the width direction is arranged radially inward of the virtual contour 16 of the tread surface under the prescribed internal pressure filling, and the tread surfaces 14 of the lateral side portions 11 and 12 are further arranged. And 15 are arranged radially inward. Here, it is preferable that the tire radial direction distance L between the virtual tread surface contour line 16 and the widthwise central tread surface 13 is in the range of 0.5 to 3 mm. If the above L is less than 0.5 mm, a good wandering suppressing effect cannot be obtained, and if the above L exceeds 3 mm, the tread 13 cannot be grounded sufficiently, and the wandering suppressing effect cannot be obtained either. Is.

The tread portion 8 has four main grooves 9a,
9b, 9c, and 9d are arranged, and the main groove 9b and 9c divide the width-direction central portion tread surface 13 of the tread portion and the width-direction side portion tread surfaces 14 and 15 of the tread portion. However, in the invention, the tread surface 13 of the tread portion is not necessarily formed by the main grooves 9b and 9c.
It does not need to be classified as. In addition, in FIG. 1, the main grooves 9b and 9c are inclined grooves that approach the tire equatorial plane toward the groove bottom. Here, the main grooves 9b and 9c may be curved.

Further, the notch groove 17 is arranged over the entire circumference of the shoulder portion of the tire 1. This groove 17 is effective because the flexural deformation (deformation in the direction of the arrow in FIG. 5) of the sidewall portion of the tire is blocked and the lateral force Fy as a reaction to the deformation can be reduced.

Next, FIG. 2 shows a typical sectional perspective view of the pneumatic tire according to the second invention. Similar to the tire shown in FIG. 1, this pneumatic tire also has a belt 5 formed by stacking two layers on the outer side in the radial direction of the crown portion 4 of the carcass 3 extending in a toroidal shape between the pair of beads 2. A radial tire having a belt reinforcing layer 6 having the same width as the above, a narrow belt reinforcing layer 7 covering an end portion of the wide belt reinforcing layer 6, and a tread portion 8.

Here, the tread surface 13 of the widthwise central portion of the tread portion
1 differs from the case of FIG. 1 and coincides with the virtual contour of the tread, and is further divided into a large number of blocks by a plurality of lateral grooves or lateral sipes 19. In FIG. 2, the tread surface on the lateral side in the width direction forms a rib. However, when the tread surface is also divided into a large number of blocks, the width of the lateral groove or lateral sipe 19 that divides the tread surface 13 can be widened or the number of the lateral grooves can be reduced. It is necessary to reduce the rigidity of the land portion of the widthwise central tread 13 by increasing the number. The lateral groove or lateral sipe may be inclined at least 30 ° with respect to the tire equatorial plane 18.

Here, if the lateral groove or lateral sipe is inclined such that the groove bottom or sipe bottom is located in front of the opening in the tire rotation direction, the braking force is further increased, which is effective.

The tread portion 8 has four main grooves 9a,
9b, 9c, and 9d are arranged, and the main groove 9b and 9c divide the width-direction central portion tread surface 13 of the tread portion and the width-direction side portion tread surfaces 14 and 15 of the tread portion. However, in the invention, the tread surface 13 of the tread portion is not necessarily formed by the main grooves 9b and 9c.
Need not be compartmentalized. In FIG. 2, the main grooves 9b and 9c are inclined grooves that approach the tire equatorial plane toward the groove bottom. Here, the main grooves 9b and 9c may be curved.

Further, in FIG. 2, the belt 5 and the belt reinforcing layers 6 and 7 have a symmetrical structure in cross section, and their widthwise positions are arranged symmetrically with respect to the tire equatorial plane. You may make it unevenly distributed like. Further, for the same reason as in FIG. 1, the cutout groove 17 is arranged over the entire circumference of the shoulder portion of the tire 1.

FIG. 3 is a sectional perspective view of the pneumatic tire according to the first invention and the second invention. In addition to the tire structure and shape shown in FIG. 1, this tire is further divided into a number of blocks in the widthwise central tread surface 13 of the tread portion by lateral grooves or lateral sipes 19, and in addition, in the widthwise central portion of the tread portion. 2 layers of narrow belt reinforcement layer 6b
Is equipped with.

Test Example Size 235/4 according to the structure and shape shown in FIG.
A 5ZR17 pneumatic radial tire was prototyped as Example 1. The belt 5 embedded in the tire is made of two layers of rubber laminated steel cords inclined at an angle of 22 ° with respect to the equatorial plane of the tire and has a width of about 22.
The belt reinforcing layer 6 disposed on the outer side in the radial direction of the belt is 0 mm, and is a layer made of rubberized nylon cords arranged at a minute angle with respect to the tire equatorial plane and has a width of 236 m.
The belt reinforcing layer 7 covering both ends of the wide belt reinforcing layer was a rubberized layer of nylon cords arranged at minute angles with respect to the equatorial plane of the tire and had a width of 45 mm.

This tire has a tread width of 185 mm, and the widthwise central tread 13 of the tread portion is 1 mm radially inward of the tread virtual contour of the tread (that is, the distance L is 1 mm), and the width of the tread surface 13 was 25 mm. The main grooves 9b and 9c were grooves having an inclination angle of about 15 ° with respect to the tire equatorial plane. In addition, the belt and the belt reinforcing layer were arranged such that their widthwise positions were offset by 10 mm on one sidewall portion side.

In the tire produced as a trial example as Example 2, two belt reinforcing layers rubberized with nylon cords arranged at a minute angle to the tire equatorial plane were used, and the width of the tread was radially outside the wide belt reinforcing layer. The structure and shape were the same as those of the tire of Example 1 except that the belt and the belt reinforcing layer were arranged symmetrically across the width of 90 mm at the central portion in the direction.

In the tire manufactured as a trial example as Example 3, the tread surface in the widthwise central portion of the tread portion coincides with the virtual contour of the tread surface (that is, the distance L is 0 mm), and a lateral sipe having a width of 0.8 mm and a depth of 7 mm is further used. The tire had the same structure and shape as those of the tire of Example 1 except that they were arranged at an angle of 90 ° with respect to the tire equatorial plane and at intervals of about 15 mm in the circumferential direction.

In the tire prototyped as Example 4, two belt reinforcing layers rubberized with nylon cords arranged at a minute angle to the tire equatorial plane were used, and two belt reinforcing layers were formed on the tread portion on the outer side in the radial direction of the wide belt reinforcing layer. The tire had the same structure and shape as those of the tire of Example 3 except that the belt and the belt reinforcing layer were arranged symmetrically across the tire equatorial plane in the widthwise central portion.

In the tire manufactured as a trial example as Example 5, a lateral sipe having a width of 0.8 mm and a depth of 7 mm was provided at the center of the tread in the width direction, and an angle of 90 ° with respect to the equatorial plane of the tire and about 15 mm intervals in the circumferential direction. The tire had the same structure and shape as the tire of Example 1 except that the tires of Example 1 were arranged.

In the tire produced as a trial example 6, two belt reinforcing layers rubberized with nylon cords arranged at a small angle to the tire equatorial plane were used, and the width of the tread was radially outside the wide belt reinforcing layer. Example 5 except that it was arranged over a width of 90 mm at the central portion in the direction, and that the belt and the belt reinforcing layer were arranged symmetrically with the tire equatorial plane sandwiched therebetween.
The tire had the same structure and shape.

As a comparative example, a tire of the same size having the structure shown in FIG. 6 was manufactured as a conventional example. This tire has a belt formed by stacking two layers on the outer side in the radial direction of a crown portion of a carcass extending in a toroidal shape between a pair of beads, a belt reinforcing layer having the same width as the belt, and the wide belt reinforcing layer. It is a radial tire provided with a narrow belt reinforcing layer that covers an end portion of a tread portion and a rib pattern in which four main grooves are arranged in the tread portion. Unlike the above-mentioned embodiment, this conventional example has a normal structure and shape, the widthwise central tread of the tread portion matches the tread virtual contour of the tread portion, and the widthwise central portion. The tread was also ribbed. Further, the belt and the belt reinforcing layer were the same as those used in Example 1, and were arranged symmetrically with the tire equatorial plane sandwiched.

The test is to attach a safety walk,
Using a flat belt tester with a speed of 50 km / h and a road surface inclination angle of 5 °, the tire internal pressure was 2.4 k.
The lateral force Fy was measured under the conditions of gf / cm ² and a tire load of 650 kgf, and was measured in the direction of rising the inclined surface. Table 1 shows the test results. The numbers in the table are
The lateral force Fy is 67 kgf, and the conventional example is shown as an index ratio with 100, and the smaller the better, the better.

[0035]

[Table 1]

From the test results, in each of Examples 1 to 6, the lateral force Fy was significantly smaller than that of the conventional example.

In addition, each test example is an F of 3000 cc class.
Mounted on an R-drive type passenger car, the rut road surface is 100 km / h
The vehicle was run at h and a feeling evaluation was performed. When the conventional example was given 5.0 points in the 10-point evaluation, the examples were all 6.6.
It was above the point, and considerable straight running stability was recognized.

[0038]

According to the present invention, it is possible to improve straight running stability on a road surface having an inclined portion, for example, a road surface having unevenness such as a rut, in a pneumatic tire, particularly a high performance tire having a reduced flatness. it can.

[Brief description of drawings]

FIG. 1 is a widthwise sectional view of a typical pneumatic tire according to a first invention.

FIG. 2 is a cross-sectional perspective view of a typical pneumatic tire according to the second invention.

FIG. 3 is a cross-sectional perspective view of the pneumatic tire according to the first and second aspects of the invention.

FIG. 4 is a view for explaining the action of the invention tire when it is in contact with the inclined surface.

FIG. 5A is a front view of a general pneumatic tire in a state where it is in contact with an inclined surface, and FIG. 5B is a cross-sectional view in the width direction of the tire.

FIG. 6 is a sectional view in the width direction of a conventional example.

[Explanation of symbols]

1 Pneumatic tire 2 Bead 3 Carcass 5 Belt 6,6a, 6b, 7 Belt reinforcement layer 9a, 9b, 9c, 9d Main groove 13 Width center tread 14,15 Width side tread 16 Virtual tread tread Contour 17 Notched groove 19 Lateral groove or lateral sipe L Tire radial distance between virtual contour of tread and center tread in width direction

Claims (6)

[Claims] 1. A pneumatic tire having a belt and a tread portion radially outside a crown portion of a carcass extending in a toroidal shape between a pair of beads, wherein a tread surface in a widthwise central portion of the tread portion is under a prescribed internal pressure filling. The pneumatic tire is arranged radially inward of the virtual contour of the tread portion of the tread portion, and radially inward so as to be in contact with the road surface when a prescribed load is further applied. 2. A pneumatic tire having a belt and a tread portion radially outside a crown portion of a carcass extending in a toroidal shape between a pair of beads, wherein a tread surface in the width direction central portion of the tread portion has a plurality of lateral grooves or A pneumatic tire characterized by being divided by lateral sipes. 3. A tread portion in the widthwise central portion of the tread portion is divided from a tread portion in the widthwise side portion by a circumferentially extending main groove, and the main groove extends toward the groove bottom toward the tire equatorial plane. The pneumatic tire according to claim 1 or 2, wherein the groove is a substantially inclined groove that is close to. 4. The pneumatic tire according to claim 1, further comprising a belt reinforcing layer having a narrow width at a widthwise central portion of the tread portion. 5. The pneumatic tire according to any one of claims 1 to 4, wherein the belt is arranged with its widthwise position unevenly distributed. 6. The pneumatic tire according to any one of claims 1 to 4, wherein the belt reinforcing layer is arranged such that its widthwise positions are unevenly distributed.