JP3993250B2 - Pneumatic radial tire - Google Patents

Description

【００１６】
また、えぐり溝を、トレッドの接地端側面部に設けることにより、第２トレッドを配置したために低下する発熱耐久性を、従来のタイヤの値近くまで向上することができる。比較例１及び比較例２は、第１トレッド５ａと第２トレッド５ｂを有するが、トレッドの接地端側面部に溝が形成されていないタイヤである。表１から明らかなように、実施例のタイヤは、比較例のタイヤに比べて、直進安定性並びに発熱耐久性が優れたタイヤとなっている。なお、発熱耐久性は、規定最大荷重（上述したサイズのタイヤにおいては１１８０ｋｇｆ）の１３０％荷重にて、ドラム上を速度６５ｋｍ／ｈで走行させた際に、トレッドの一部が、ベルト或いはカーカスから剥離故障するまでの走行距離を、従来のタイヤの剥離故障するまでの走行距離１９７００ｋｍを１００としたときの指数として表したものである。
【００１７】
【発明の効果】
本発明は、以上説明したように構成されているので、以下に記載するような効果を奏する。
【００１８】
空気入りラジアルタイヤのワンダリング現象の発生を抑制することができるとともに、轍の凹凸等の傾斜部分を有する路面での直進安定性及び発熱耐久性を向上させることができる。
【図面の簡単な説明】
【図１】図１は本発明の空気入りラジアルタイヤのタイヤ幅方向の断面図である。
【図２】図２は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３】図３は本発明の空気入りラジアルタイヤが傾斜路面と接地した状態を示すタイヤ幅方向の断面図である。
【図４】図４は従来の空気入りラジアルタイヤのタイヤ幅方向の断面図である。
【符号の説明】
１・・・・・・空気入りラジアルタイヤ
２・・・・・・カーカス
３・・・・・・ビードコア
４・・・・・・ベルト
５・・・・・・トレッド
５ａ・・・・・第１トレッド
５ｂ・・・・・第２トレッド[0001]
[Industrial application fields]
The present invention relates to a pneumatic radial tire, and more particularly to a pneumatic radial tire (hereinafter, also simply referred to as “tire”) used in passenger cars, light trucks, small trucks / buses, trucks / buses, and the like.
[0002]
[Prior art]
Conventionally, a so-called radial tire in which carcass cords are arranged in a direction substantially perpendicular to the tire equatorial plane is known, and has superior wear resistance and steering stability compared to a tire having a bias structure. Therefore, in recent years, it is used not only in passenger cars but also in vehicles such as small trucks and trucks / buses.
[0003]
[Problems to be solved by the invention]
When traveling on a road surface having an inclined portion, for example, a road surface having unevenness such as a saddle, a complicated movement of the vehicle that the driver cannot predict, a so-called phenomenon called wandering may occur. Although the use of radial tires has increased along with the increase in the speed of vehicles, the frequency of occurrence of the above-mentioned wandering phenomenon has increased as the vehicles are driven on a daily basis due to the development and expansion of the road network. This wandering is a dangerous phenomenon that impairs the straightness of the vehicle, and is therefore a major problem as the performance of tires increases.
[0004]
An object of the present invention is to solve the problems of the conventional pneumatic radial tire described above and to provide a pneumatic radial tire with improved straight running stability and heat generation durability.
[0005]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present invention is a pneumatic radial tire in which a belt and a tread are arranged on the outer side in the tire radial direction of a carcass that is straddled between a pair of bead cores. The first tread that fills the internal pressure stipulated in the JATMA standard and contacts the flat road with a load of 70% of the maximum load capacity, and extends outward in the tire width direction from the first tread. The tread end of the second tread is grounded at the mountain side of the sloped road surface, and the tread end of the second tread has a ground contact width when the angle between the tire equator line and the vertical line of the road surface is 10 ° under the above-described state. disposed out tension outward in the tire width direction than, and, is provided with a groove having a depth in the tire width direction to the ground end side portion of the tread.
[0006]
1 is a cross-sectional view of the pneumatic radial tire of the present invention in the tire width direction, FIG. 2 is a schematic diagram showing a state where the tire is in contact with the inclined road surface, and a tire where the tire is in contact with the inclined road surface. The present invention will be described with reference to FIG. 3 which is a sectional view in the width direction.
[0007]
Reference numeral 1 denotes a pneumatic radial tire. The tire 1 includes a carcass 2 including at least one carcass ply in which a cord is substantially orthogonal to the tire equator plane, and a pair of bead cores 3. A belt 4 made of at least two plies in which a cord layer in which cords arranged in parallel to each other are covered with rubber is laminated so that the cords cross each other, and the belt 4 is arranged on the outer side in the tire radial direction. The carcass 2 is arranged across a pair of bead cores 3 in a toroidal shape. In addition, 6 is a tire side part.
[0008]
The tread 5 described above has a tread end 5 ′ protruding outward in the tire width direction, a first tread 5 a that contacts the ground on a flat road, and extends outward in the tire width direction from the first tread 5 a, and is inclined. The second tread 5b is grounded on the mountain side of the road surface. More specifically, the first tread 5a and the second tread 5b described above are configured by a loose curved line having a predetermined radius of curvature, and the internal pressure and the maximum load capacity defined in the JATMA standard. The tread that contacts the flat road is the first tread 5a, and the tread that extends outward in the tire width direction of the first tread 5a and newly contacts the mountain side of the inclined road surface is the second tread. 5b. When the road surface inclination angle at this time, that is, the angle between the tire equator line and the vertical line of the road surface is 10 °, the tread end 5 ′ of the second tread 5b protrudes outward in the tire width direction from the ground contact width. Be placed.
The actual load used is about 70% of the maximum load capacity of JATMA standard, and the inclination angle of the uneven slope such as a bottleneck is about 10 ° even if it is too large. It is practically sufficient to have two treads 5b.
[0009]
As shown in FIG. 2, when the tire is going to cross a sloped road surface such as a corrugated surface with a certain approach angle, the tire 1 has a reaction force Fr from the road surface, the tire 1 and the sloped road surface. Lateral force Fy is generated by the camber thrust Fc generated between the two. By the way, when the tire is made radial, the rigidity of the tire becomes high, and the reaction force Fr from the road surface is large and the caber thrust Fc is small as compared with the tire of the bias structure, so that the lateral force Fy becomes large. Therefore, it has been found that in order to ride on an inclined road surface, the approach angle has to be increased, and smooth wandering cannot be carried out and wandering occurs. Therefore, in order to suppress the wandering phenomenon in the radial tire, it is effective to reduce the lateral force Fy by increasing the camber thrust Fc.
[0010]
As shown in FIG. 3, the collapse deformation Bside of the tire side portion 6 that occurs when the tire 1 contacts and bends on an inclined road surface causes a bending deformation Bsho of the tread 5 near the ground contact. It was found that the lateral force Fsho in the direction of climbing the inclined road surface generated by the shear deformation Ssho of the tread 5 caused by the above contributes to the increase of the camber thrust Fc. Therefore, in order to increase the camber thrust Fc, it is only necessary to increase the bending deformation Bsho of the tread 5 in the vicinity of the ground contact by making the collapse side deformation Bside of the tire side portion 6 easily transmitted to the ground contact end portion. The tread 5 in the vicinity of the end may be grounded more widely, particularly when grounded on an inclined road surface.
[0011]
As in the present invention, by providing the second tread 5b extending outward in the tire width direction from the first tread 5a and grounding on the mountain side of the inclined road surface, the contact width on the inclined road surface with an inclination of up to 10 ° can be obtained. Can be enlarged. Further, in a tire having such a wide tread, the thickness of the tread near the end of the tread is increased, and thus the heat generation durability is deteriorated. However, the provision of the heat radiation portion prevents the heat generation durability from being deteriorated. be able to. As shown in FIG. 1, such a heat radiating portion can be formed by providing a concave portion or a groove 7 having a predetermined depth in the tire width direction on the grounded side surface portion of the tread. By providing a heat radiating part, it is possible to improve the heat radiating property in the vicinity of the tread end part and to suppress the heat generation durability.
[0012]
【Example】
Next, a conventional pneumatic radial tire as shown in FIG. 4, which has a first tread 5 a and a second tread 5 b, but a comparative example in which the groove 7 is not provided on the side surface of the ground end of the tread 5, A comparative test with the example of the present invention will be described.
[0013]
The tires are all light truck tires, the size is 195 / 85R16 114/112 LT, and the maximum load capacity is 1180 kgf (JATMA). In the tires of the examples, the tread contour line has a radius of curvature of 300 mm from the tire equatorial plane to the outer side in the tire width direction of 37.6 mm, and from the tire equatorial plane to the outer side in the tire width direction from 37.6 to 80.0 mm. The radius of curvature was 100 mm, and the outer side in the width direction was an arc having a curvature radius of 50 mm. On the other hand, the conventional tire does not have the above-described second tread, and includes only the first tread having a curvature radius of 300 mm. That is, the tread is grounded over a substantially flat area. Moreover, in the Example, the large groove | channel was provided in the side surface part of the grounding end of a tread, and the thickness of the side part part decreased to 2 mm from 9.2 mm by this groove | channel. Thus, the heat radiating part can be provided up to the vicinity of the carcass.
[0014]
After these tires are filled with a specified internal pressure of 6.0 kgf / cm ^2, they are mounted on a 2-ton stacked small truck (rear wheel is a multi-wheel type), and the pavement includes scissors with the specified maximum load applied to the small truck. A test driver drove along the road and sensory evaluated straight running stability. The results are shown in Table 1 by index evaluation with the conventional tire as 100 (the larger the index, the better the straight running stability). As is clear from Table 1, the tires of the examples of the present invention have significantly improved straight running stability as compared with the conventional tires.
[0015]
[Table 1]

[0016]
Further, by providing the countersunk groove on the side surface portion of the contact end of the tread, it is possible to improve the heat generation durability that is lowered due to the arrangement of the second tread to a value close to that of the conventional tire. The comparative example 1 and the comparative example 2 are tires having the first tread 5a and the second tread 5b, but having no groove formed on the side surface portion of the contact end of the tread. As is clear from Table 1, the tires of the examples are excellent in straight running stability and heat generation durability compared to the tires of the comparative examples. The heat generation durability is determined by the fact that a part of the tread is belt or carcass when running on the drum at a speed of 65 km / h with a 130% load of the specified maximum load (1180 kgf for the tire of the above-mentioned size). The distance traveled until the failure of peeling is expressed as an index when the traveling distance 19700 km until the failure of the conventional tire is defined as 100.
[0017]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
[0018]
The occurrence of the wandering phenomenon of the pneumatic radial tire can be suppressed, and the straight running stability and the heat generation durability on the road surface having the inclined portion such as the unevenness of the ridge can be improved.
[Brief description of the drawings]
FIG. 1 is a sectional view of a pneumatic radial tire of the present invention in the tire width direction.
FIG. 2 is a schematic view showing a state in which a tire is in contact with an inclined road surface.
FIG. 3 is a cross-sectional view in the tire width direction showing a state in which the pneumatic radial tire of the present invention is in contact with an inclined road surface.
FIG. 4 is a cross-sectional view of a conventional pneumatic radial tire in the tire width direction.
[Explanation of symbols]
1 .... Pneumatic radial tire 2 .... Carcass 3 .... Bead core 4 ... Belt 5 ... Tread 5a ... No. 1 tread 5b ... 2nd tread

Claims (1)

A pneumatic radial tire in which a belt and a tread are arranged on the outer side in the tire radial direction of a carcass straddling a pair of bead cores, and the tread is filled with an internal pressure defined in JATMA standards. The first tread that contacts the flat road with a load of 70% of the maximum load capacity, and the second tread that extends outward in the tire width direction from the first tread and contacts the mountain side of the inclined road surface. the tread end of the second tread, under the condition, when the angle between the vertical line of the tire equator line and the road surface and 10 °, are disposed out tension outward in the tire width direction than the contact width And the pneumatic radial tire characterized by providing the groove | channel which has a depth in the tire width direction in the side surface part of the contact end of a tread.

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