JP3623554B2 - Pneumatic radial tire - Google Patents

Description

【００２０】
すなわち、この発明によれば、空気入りラジアルタイヤのワンダリングを抑制して轍路等の傾斜路面上での直進安定性を向上させることができる。
【図面の簡単な説明】
【図１】この発明に従う空気入りラジアルタイヤのタイヤ幅方向断面図である。
【図２】この発明に従う補強層を配置した空気入りラジアルタイヤのタイヤ幅方向断面図である。
【図３】従来例のタイヤ幅方向断面図である。
【図４】タイヤが傾斜路面と接地した状態を示す模式図である。
【図５】タイヤが傾斜路面と接地した状態における変形及び横力を示す模式図である。
【符号の説明】
１ 空気入りラジアルタイヤ
２ カーカス
３ ベルト
４ トレッド
５ 溝
６ ゴム層
７ 補強層
Ｍ タイヤ赤道面[0001]
BACKGROUND OF THE INVENTION
The present invention, road surface having a ramp portion and for example complex movements of the vehicle driver can not be predicted to occur when traveling on a road surface having irregularities such as rutting, improve straight running stability by suppressing a so-called wandering This is a pneumatic radial tire, and particularly relates to light truck tires and light truck tires, truck and bus tires.
[0002]
[Prior art]
In recent years, so-called radial tires in which carcass cords are arranged in a direction substantially perpendicular to the tire equator plane, not only in passenger cars but also in light trucks, light trucks, trucks, buses, and other vehicles, are more resistant to wear than bias tires. Has been widely used because of its excellent performance and steering stability.
[0003]
[Problems to be solved by the invention]
The use of radial tires has increased along with the increase in vehicle speed, but the frequency of occurrence of the wandering problem has increased when vehicles have been running at high speed on a daily basis due to the development and expansion of the road network. I came. This wandering is a dangerous phenomenon that impairs the straight running stability of the vehicle, and has become a major problem as the performance of tires increases.
[0004]
Accordingly, an object of the present invention is to propose a pneumatic radial tire that suppresses wandering and improves straight running stability on an inclined road surface such as a saddle.
[0005]
[Means for Solving the Problems]
In the present invention, a belt and a tread are sequentially arranged on the outer periphery of a crown portion of a carcass straddling a toroidal shape between a pair of bead cores, and the belt has a laminated arrangement of at least two belt layers. The belt layer has a widthwise cross-sectional shape that protrudes outward in the tire radial direction at the center portion of the tread as compared with the carcass shape, and is a pair of grooves that are located closest to the tire equatorial plane and extend substantially in the tire circumferential direction. Compared to the groove depth hc, the pneumatic radial tire is characterized in that the groove depth hs of the pair of grooves located closest to the ground contact end and extending substantially in the tire circumferential direction is larger. .
[0006]
As shown in FIG. 4, when a tire tries to cross an inclined road surface such as an uneven surface of a kite with an approach angle, the tire has a camber thrust FC generated between the reaction force FR from the road surface and the inclined road surface. The lateral force Fy due to works. Here, when the tire is made radial, the rigidity of the tire becomes higher, and the reaction force FR is larger and the camber thrust FC is smaller than that of the bias tire. It was not possible and wandering was found to occur. Therefore, in order to suppress wandering in the radial tire, it is effective to reduce the lateral force Fy by increasing the camber thrust FC.
[0007]
The camber thrust FC is generated by bending deformation in the tire cross section of the tread when the tire contacts the inclined road surface and is deformed by bending. That is, as shown in FIG. 5, it can be considered that the influence of the lateral force FCS generated by the tread bending deformation bS in the vicinity of the tread grounding end is great. Therefore, in order to increase the camber thrust FC, the lateral force FCS may be increased.
[0008]
According to this invention, since the innermost belt layer has a cross-sectional shape that is convex outward in the tire radial direction, the bending deformation bs of the tread that tends to become flat with grounding increases, and as a result, the tread grounding occurs. The lateral force Fcs generated near the end can be increased.
[0009]
Further, as compared with the groove depth hc of the grooves of the pair extending in a substantially circumferential direction of the tire and located closest to the tire equatorial plane, it extends substantially tire circumferential direction and located closest to the ground terminal 1 by groove depth hs of the pair of grooves is large, the belt of the grounding end near the time of vulcanization molding of tire manufacture is, by the groove deep grounding end near the equatorial plane near the tire mold, Since it is pushed down, the convex shape is further strengthened.
[0010]
Further, it is preferable that a rubber layer is interposed between the innermost belt layer in the radial direction and at a position including the tire equatorial plane, and the tread position corresponding to the end of the rubber layer is closest to the tire equatorial plane. and, by placing a substantially groove pair extending in the tire circumferential direction, increases deformation bs Gayori bending of the tread, the lateral force Fcs generated in the vicinity of the tread ground contact end portion can be further increased.
Further, at the time of vulcanization molding, the groove can prevent the rubber layer from flowing out to the outer periphery in the width direction, thereby further strengthening the convex shape.
[0011]
In addition, by arranging at least one reinforcing layer having a width of 0.1 to 0.3 times the groove of the widest belt layer in the vicinity of the end of the belt, the convex shape at the time of internal pressure filling is further increased. Since the strength of the belt can be increased and the rigidity of the belt can be increased, the bending deformation bS of the tread can be significantly increased.
Here, the width of the widest belt layer is set to 0.1 to 0.3 times the width. If the width is smaller than 0.1 times, the convex shape cannot be sufficiently strengthened. although improved, the protruded not be strengthened, because the can not be obtained sufficient improvement effect of both placing the reinforcing layer.
In addition, although the reinforcement layer can be expected to improve the bending deformation bs even if it is disposed at any position outside the belt in the radial direction, inside the belt, or inside the belt in the radial direction, in order to further strengthen the convex shape. It is preferable to arrange the belt radially outside the belt.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
A pneumatic radial tire 1 for small trucks of size 195 / 85R16 114 / 112LT following the structure shown in FIG. 1 was manufactured according to the specifications shown in Table 1 by changing the groove arrangement. In FIG. 1, the carcass 2 is formed by laminating three rubber-coated plies in which a large number of polyester cords are arranged in the radial direction, and a belt 3 and a tread 4 are disposed on the outer periphery of the carcass 2. The belt 3 is composed of three steel belt layers , a belt layer 3-1 (hereinafter also referred to as a first belt layer ) adjacent to the carcass and having a relatively large inclination angle with respect to the tire equatorial plane of the cord, the belt is disposed on the outer periphery of the layers 3-1, the inclination angle is relatively small belt layer 3-2 with respect to the tire equatorial plane of the code (hereinafter, also referred to as a second belt layer) refers 3-3 (hereinafter, also the third belt layer 2) are laminated such that the cords intersect with each other across the tire equator plane.
[0013]
【Example】
Here, an example is shown below.
The first belt layer has a cord inclination angle of 52 ° and a width of 120 mm, the second belt layer has a cord inclination angle of 24 ° and a width of 135 mm, and the third belt layer has a cord inclination angle of 24 ° and a width of 120 mm. Of these three belt layers , the widest belt layer is the second belt layer , and this width is BW.
The tread is provided with four grooves 5 extending substantially continuously in the tire circumferential direction. Further, illustration of the vicinity of the bead core is omitted.
[0014]
Example 1
By arranging the rubber layer 6 between the carcass 2 and the first belt layer 3-1 at a position including the tire equatorial plane M, the belt 3 has a cross section in the width direction that protrudes outward in the tire radial direction at the center of the tread. Has a shape. Here, in the manufactured tire, the rubber layer 6 was disposed so that the center of the width substantially coincided 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 cross-sectional shape of the rubber layer 6 is substantially rectangular, the second and third belt layers have a cross-sectional shape in the width direction that protrudes outward in the tire radial direction with a step.
However, the present invention is not limited thereto, and for example, the cross-sectional shape of the rubber layer 6 may be a convex lens cross-sectional shape. When the convex lens has a cross-sectional shape, a wandering suppressing effect can be expected particularly when the vehicle is empty or when the camper angle is small.
Here, the circumferential groove depth was 9.5 mm for the pair of grooves closest to the tire equatorial plane and 12 mm for the pair of grooves closest to the ground contact edge.
In the case of Figure 1, grooves 5-1 located closest to the tire equatorial plane, located at a distance of 16mm from the tire equatorial plane, is disposed in a corresponding tread located between the end portion of the rubber layer 6 However, the wandering suppressing effect is larger in such an arrangement.
[0015]
Example 2
Example 2 is substantially the same as Example 1 except that the pair of grooves 5-1 located closest to the tire equatorial plane is located at a distance of 25 mm from the tire equatorial plane.
[0016]
Example 3
In Example 3, two nylon reinforcing layers 7 having a width of 20 mm, which is 0.15 times the width of the widest belt layer, are arranged on the outer side in the radial direction of the belt near the end of the belt as shown in FIG. Except for this, the second embodiment is almost the same as the second embodiment.
[0017]
Conventional Example As a conventional example, a tire having the above size according to the structure shown in FIG. 3 was prepared.
The difference from the first embodiment, the circumferential groove depth, a pair and the tire equatorial plane side, together with a pair of ground contact edge side, and 10.5 mm, also by the absence of the rubber layer 6, the belt This is because the layer does not have a cross-sectional shape in the width direction that is convex outward in the tire radial direction at the center portion of the tread as compared with the shape of the carcass 2.
[0018]
After these tires are filled with a specified internal pressure of 6.0kgf / cm ^2, they are mounted on a 2 ton light truck (rear wheel is a multi-wheel type), and a pavement that includes ridges with the specified maximum load applied to the light truck. A test driver drove and sensory evaluated the straight-line stability. The results are also shown in Table 1 by index evaluation (the larger the index is, the better) with the conventional example being 100. 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]

[0020]
That is, according to the present invention, it is possible to improve the straight running stability on an inclined road surface such as a rutted road by suppressing wandering of the pneumatic radial tire.
[Brief description of the drawings]
FIG. 1 is a sectional view in the tire width direction of a pneumatic radial tire according to the present invention.
FIG. 2 is a sectional view in the tire width direction of a pneumatic radial tire provided with a reinforcing layer 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 an inclined road surface.
FIG. 5 is a schematic diagram showing deformation and lateral force when the tire is in contact with an inclined 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 equator

Claims (3)

A belt and a tread are sequentially arranged on the outer periphery of the crown portion of the carcass that is formed in a toroidal shape between a pair of bead cores, and the belt is a laminated arrangement of at least two belt layers. Groove depth of a pair of grooves that have a cross-sectional shape that protrudes outward in the tire radial direction at the center portion of the tread compared to the carcass shape, and that is closest to the tire equatorial plane and extends substantially in the tire circumferential direction A pneumatic radial tire characterized in that the groove depth hs of the pair of grooves that are located closest to the ground contact end and extend substantially in the tire circumferential direction is larger than hc. The rubber layer is disposed radially inward of the innermost belt layer, and a pair of grooves closest to the tire equatorial plane is disposed at a tread position corresponding to an end of the rubber layer. Pneumatic radial tire. Near the end of the belt, pneumatic radial tire according to claim 1 or 2 arranged at least one reinforcing layer having a 0.1 to 0.3 times the width of the widest belt layer.

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