JP4305632B2 - Heavy duty pneumatic radial tire - Google Patents

Description

表１より、実施例１，２は従来例に比してベルトセパ耐久性及びエッジセパ性に優れていることを確認した。
【００２４】
【発明の効果】
上述したように、本発明の重荷重用空気入りラジアルタイヤは、第一ベルト層と第二ベルト層との間に、タイヤ周方向に対するコード角度が５°以下のスチールコードからなる補強層を配置するに当り、その補強層をタイヤ幅方向の中央部で分離し間隔を隔てるように配置し、かつ両端部でそれぞれ第二ベルト層の両端部を覆うようにしたので、ベルト層の中央部では層間のセパレーションを抑制し、かつベルト層端部ではせり上がりを抑制してベルト層端部におけるセパレーションを抑制することができる。
【図面の簡単な説明】
【図１】本発明の重荷重用空気入りラジアルタイヤのトレッド部の一例を示す断面図である。
【図２】図１の要部を拡大して示す断面図である。
【図３】（ａ）及び（ｂ）は補強層の形態の一例を示す平面図である。
【図４】従来の重荷重用空気入りラジアルタイヤの変形状態を説明するためのタイヤの半断面図である。
【図５】図４のタイヤの接地形状を説明するための説明図である。
【符号の説明】
１ トレッド部
２ カーカス層
５ 補強層
１Ｂ 第一ベルト層
２Ｂ 第二一ベルト層
３Ｂ 第三ベルト層
４Ｂ 第四ベルト層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heavy-duty pneumatic radial tire. More specifically, even when the tire is flattened, the durability of the tire is improved by suppressing the peeling from the end of the belt layer. The present invention relates to a suitable heavy duty pneumatic radial tire.
[0002]
[Prior art]
A heavy-duty pneumatic radial tire is filled with a larger air pressure than a passenger car tire, and therefore, it rises in the vicinity of the end of the belt layer, which causes a separation of the end of the belt layer. In recent years, flattening of heavy-duty pneumatic radial tires has also progressed, and as the flattening progresses, the load on the belt layer further increases, so that the separation is more likely to occur.
[0003]
In other words, since a heavy-duty pneumatic radial tire generally has three or more belt layers made of steel cord and has high rigidity, as shown in FIG. Since the wall portion W and the shoulder portion S are deformed in the direction of the arrow so as to approach the equilibrium profile shape, the belt edge portion B whose deformation is suppressed at the center portion of the tread moves in the direction of increasing the diameter. When the tire is run in this state, the ground contact shape of the tire becomes a shape projecting in the traveling direction of the tire because the ground contact area of both shoulder portions S increases as illustrated in FIG.
[0004]
Therefore, the shear stress is locally generated in the belt edge portion B, and the shear stress generated by the centrifugal force during running of the tire is added to the belt edge portion B, so that the belt edge portion B is easily separated.
[0005]
As a countermeasure against such a problem, a heavy-duty pneumatic tire is proposed in which the steel cords of the belt layer are arranged in a wavy or zigzag shape in the tire circumferential direction so that the cord end portions are not arranged at the belt layer end portions ( For example, see Patent Document 1.)
[0006]
[Patent Document 1]
JP-A-2-81707 (page 1-6, FIGS. 1 and 4-8)
[0007]
[Problems to be solved by the invention]
However, in the above proposal, it is difficult to stretch the steel cord completely straight even if the belt layer is lifted in the radial direction by the molding vulcanization operation, and it remains in a wave shape after vulcanization. The centrifugal force causes a shear deformation in the tire width direction between the belt layers, and there is a drawback that separation between the belt layers is likely to occur.
[0008]
The object of the present invention is to eliminate such conventional problems and to prevent separation between the belt layers even if the flattening of the tire is advanced, and to suppress the separation of the belt layer end portion. The object is to provide a heavy-duty pneumatic radial tire suitable for a flat tire of 80 or less.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the heavy-duty pneumatic radial tire of the present invention has a first belt layer made of a steel cord having a cord angle of 40 to 60 ° with respect to the tire circumferential direction on the outer periphery of the carcass layer in the tread portion, In the heavy-duty pneumatic radial tire in which at least two second and third belt layers made of a steel cord having a cord angle with respect to a tire circumferential direction of 10-30 ° are arranged on an outer periphery of the first belt layer, the first belt A reinforcing layer made of a steel cord having a cord angle with respect to the tire circumferential direction of 5 ° or less is inserted between the layer and the second belt layer, and the reinforcing layer has a width of the second belt layer at the center in the width direction. In addition to being divided at intervals of 30 to 50%, both end portions in the width direction are folded back toward the tire tread portion so as to cover the edge portion of the second belt layer. To.
[0010]
Thus, when the reinforcing layer made of a steel cord having a cord angle with respect to the tire circumferential direction of 5 ° or less is disposed between the first belt layer and the second belt layer, the reinforcing layer is arranged at the center portion in the tire width direction. In order to prevent separation between the layers at the center of the belt layer and at the end of the belt layer. The rising is suppressed, and separation at the belt layer end can be suppressed.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description is omitted.
[0012]
FIG. 1 is a cross-sectional view showing an example of a tread portion of a heavy duty pneumatic radial tire of the present invention. Reference numeral 1 denotes a tread portion, 2 denotes a carcass layer, 1B denotes a first belt layer, 2B denotes a second belt layer, 3B denotes a third belt layer, 4B denotes a fourth belt layer, and 5 denotes a reinforcing layer.
[0013]
A first belt layer 1B made of steel cord having a cord angle with respect to the tire circumferential direction of 40 to 60 ° is disposed on the outer periphery of the carcass layer 2 in the tire tread portion 1, and a tension member is disposed on the outer periphery of the first belt layer 1B. The second belt layer 2B and the third belt layer 3B made of the same steel cord are disposed. The cord angles of the steel cords of the second belt layer 2B and the third belt layer 3B with respect to the tire circumferential direction are 10 to 30 °, and are arranged so as to intersect each other between the layers. On the outer periphery of the third belt layer 3B, a fourth belt layer 4B serving to protect damage from the outside of each belt layer is disposed. The fourth belt layer 4B is also made of a steel cord, and the cord angle with respect to the tire circumferential direction is 10 to 30 °.
[0014]
The reinforcing layer 5 is formed of a steel cord disposed between the first belt layer 1B and the second belt layer 2B and arranged at an angle of 5 ° or less with respect to the tire circumferential direction. The reinforcing layer 5 is divided at a central portion in the tire width direction with a gap W1, and both end portions are folded back toward the tread portion 1 so as to cover both end portions in the width direction of the second belt layer 2B. As shown in FIG. 2, the end portion of the reinforcing layer 5 folded back to the tread portion 1 side is sandwiched between the second belt layer 2B and the fourth belt layer 4B, and the terminal 5a is connected to the third belt layer. A space is provided between the terminal 3Ba of the 3B or a face-to-face arrangement without a space. Thus, by dividing the reinforcing layer 5 so as to open the interval W1 at the center of the tread portion 1, interlayer separation at the center portion of the belt layer can be suppressed. Further, the reinforcing layer 5 can suppress the rise at the end portion of the tread portion, and edge separation can be suppressed by covering both ends of the second belt layer 2B.
[0015]
The interval W1 between the reinforcing layers 5 divided at the center of the tread is set to 30 to 50% of the width W0 of the second belt layer 2B. If the interval W1 is less than 30% of the width W0 of the second belt layer 2B, the belt peel resistance decreases with buckling of the tire center portion, and if it exceeds 50%, the contact pressure in the shoulder portion region due to insufficient contact length in the tire traveling direction. Concentration occurs and shoulder wear progresses.
[0016]
In addition, the reinforcing layer 5 is arranged so that the steel cords are arranged at an angle of 5 ° or less with respect to the tire circumferential direction as described above. It is preferable to use one whose elongation is adjusted to 7 to 8%. However, when a normal steel cord having a relative elongation of 2% or less is used, it is preferable that the steel cord is separated in a predetermined direction in the longitudinal direction as shown in FIGS. 3 (a) and 3 (b).
[0017]
That is, as illustrated in FIG. 3A or 3B, the reinforcing layer 5 is divided into a plurality in the tire circumferential direction. FIG. 3 (a) shows a case where the reinforcing layer 5 is continuous in the width direction and divided into the length L1 in the circumferential direction, and FIG. 3 (b) divides the reinforcing layer 5 into two rows in the width direction and surrounds each of them. The case where it divides | segments into length L1 in the direction is shown. The length L1 is not particularly limited, but is preferably in the range of 1.5 to 4.0% of the tire outer diameter L0. When the length L1 is less than 1.5% of the tire outer diameter L0, it is difficult to suppress the outer diameter growth of the tire, and when the length L1 is longer than 4.0%, the separation suppressing action between the belt layers is lowered. In addition, it is preferable to make small the space | interval of the circumferential direction of each divided reinforcement layer 5 in the range which does not inhibit a shaping | molding operation | work.
[0018]
Further, the second belt layer 2B is made of rubber whose 100% modulus is 3.5 to 6.5 MPa, and the thickness of the portion covered by the folded portion of the reinforcing layer 5 is the second belt layer 2B. It is preferable that the diameter is 1.5 times or more of the diameter of the steel cord constituting the wire. If the 100% modulus of the coated rubber is less than 3.5 MPa, the movement of the end of the second belt layer 2B cannot be suppressed, and separation tends to occur, and if it exceeds 6.5 MPa, the second end of the reinforcing layer 3 at the folded terminal 3a is likely to occur. Separation easily occurs between the belt layer 2B and the belt layer 2B. Further, when the thickness of the coat rubber covered by the folded portion of the reinforcing layer 5 is less than 1.5 times the diameter of the steel cord constituting the second belt layer 2B, separation is likely to occur from the end of the second belt layer 2B. Become.
[0019]
The above-described heavy-duty pneumatic radial tire of the present invention is effective regardless of the flatness, but is preferably applied particularly to a tire with a flatness of 80 or less with a large proportion of rising near the end of the belt layer.
[0020]
[Experimental example]
The tire size is 435 / 45R22.5, all the specifications except the presence and absence and form of the reinforcing layer 5 shown in FIG. The experimental tires (Examples 1 and 2 and Comparative Examples 1 and 2) were made different as described above. A steel cord having a relative elongation of 2% was used for the reinforcing layer, and the ratio of L1 / L0 in the longitudinal direction was set to 3.0%.
[0021]
The above five types of tires are mounted on a rim (22.5 × 14.00), filled with air pressure (900 KPa), and measured for belt separation durability and edge separation properties. Described. The larger the value, the better.
[0022]
[Evaluation method of belt separation durability and edge separation properties]
The running distance until the tire broke was measured by an indoor drum running test (speed: 45 km / h, load load: 140% of normal load), and the broken tire was disassembled to measure the length of the edge separator.
[0023]
[Table 1]

From Table 1, it was confirmed that Examples 1 and 2 were superior in belt separation durability and edge separation properties compared to the conventional example.
[0024]
【The invention's effect】
As described above, in the heavy-duty pneumatic radial tire of the present invention, a reinforcing layer made of a steel cord having a cord angle with respect to the tire circumferential direction of 5 ° or less is disposed between the first belt layer and the second belt layer. The reinforcing layer is separated at the center part in the tire width direction and arranged so as to be spaced from each other, and the both end parts of the second belt layer are respectively covered at both end parts. The separation at the end of the belt layer can be suppressed and the rise at the end of the belt layer can be suppressed to suppress the separation at the end of the belt layer.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a tread portion of a heavy duty pneumatic radial tire of the present invention.
FIG. 2 is an enlarged cross-sectional view showing a main part of FIG.
FIGS. 3A and 3B are plan views showing an example of a form of a reinforcing layer. FIGS.
FIG. 4 is a half sectional view of a tire for explaining a deformation state of a conventional heavy-duty pneumatic radial tire.
5 is an explanatory diagram for explaining a ground contact shape of the tire of FIG. 4;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tread part 2 Carcass layer 5 Reinforcement layer 1B 1st belt layer 2B 2nd 1st belt layer 3B 3rd belt layer 4B 4th belt layer

Claims (4)

A first belt layer made of a steel cord having a cord angle of 40 to 60 ° with respect to the tire circumferential direction is disposed on the outer periphery of the carcass layer in the tread portion, and a cord angle with respect to the tire circumferential direction of the first belt layer is 10 to 30 In a heavy-duty pneumatic radial tire in which at least two layers of second and third belt layers made of steel cord of ° are arranged,
A reinforcing layer made of a steel cord having a cord angle with respect to the tire circumferential direction of 5 ° or less is inserted between the first belt layer and the second belt layer, and the reinforcing layer is inserted into the second belt at the center in the width direction. A heavy-duty pneumatic radial tire that is divided at intervals of 30 to 50% of the width of the layer, and that both end portions in the width direction are folded back toward the tire tread so as to cover the edge portion of the second belt layer. The heavy-duty pneumatic radial tire according to claim 1, wherein the reinforcing layer is divided into a length of 1.5 to 4.0% of a tire outer diameter in a tire circumferential direction. The cover rubber of the second belt layer has a 100% modulus of 3.5 to 6.5 MPa, and the thickness of the portion covered with the folded portion of the reinforcing layer is the thickness of the steel cord constituting the second belt layer. The heavy-duty pneumatic radial tire according to claim 1 or 2, wherein the radial tire is at least 1.5 times the diameter. 4. The heavy-duty pneumatic radial tire according to claim 1, wherein the flat load of the heavy-duty pneumatic radial tire is 80 or less.

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