JPH09263107A - Pneumatic radial tire for heavy load - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve cut-through resisting characteristics by a method wherein at least three rubber-covered cord layers form a main cross belt layer formed such that the rubber-covered cord layers are laminated at a specified angle so that cords cross each other between the adjoining layers, and the two layers of the three layers form a narrow belt layer. SOLUTION: At least three rubber-covered cord layers 1B-3B wherein a belt B arranged at the outside in the radial direction of the crown part of a carcass ply is formed such that a plurality of cords are embedded in a covering rubber consist of a main cross belt layer laminated at the cord angle of the equator line of a tire with a peripheral direction being 5-40 deg. so that cords cross each other between adjoining layers. The maximum cross width of the main cross belt layer is approximate 70-85% of the section width of a tread. At least two layers 1B and 3B of three belt layers form a narrow belt layer having a section width being 50-65% of the maximum width of the main cross belt layer, and the cord angle thereof is set to 5-15 deg. with a peripheral direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heavy-duty pneumatic tire, and more particularly to a heavy-duty pneumatic radial tire mainly for running on rough terrain.

[0002]

2. Description of the Related Art Generally, heavy-duty pneumatic tires, such as pneumatic tires for construction vehicles, are sometimes used on rough roads or rough terrain where rocks and crushed stones are scattered, in which case cut / separation failure occurs. Is likely to occur. Here, a cut separation failure means that when the tire steps on a protrusion such as rock or crushed stone, the tread rubber receives a deep cut damage that reaches the belt, and eventually the outer circumference of the belt is damaged from this cut damage part. A separation failure that occurs along the surface. In order to prevent such separation failures, conventional heavy-duty pneumatic radial tires have a design method that increases the circumferential bending rigidity of the belt by reducing the arrangement angle of the cords in the belt layer with respect to the circumferential direction. It had been. However, if the arrangement angle of the cords with respect to the circumferential direction is made smaller to increase the bending rigidity in the circumferential direction of the belt, when the tire steps on the protrusion such as rock or crushed stone, the envelope power characteristic that wraps the protrusion decreases. The cut penetration resistance of the tire deteriorates.

[0003]

Therefore, the present applicant has
In order to provide a tire with excellent cut / separation resistance and cut / penetration resistance, the cross-sectional width of the belt layer with a small cord arrangement angle with respect to the circumferential direction is set to about 50 to 60% of the maximum width of the main cross belt layer. It was proposed in Japanese Patent Application No. 6-200847 to narrow the width. With this tire design method, the cut and separation resistance and the cut penetration resistance when stepping on relatively dull projections are compatible at a high level, but the cut penetration resistance when stepping on sharp projections is insufficient. It turned out to be

The object of the present invention is to eliminate the above-mentioned drawbacks of conventional tires, and to provide cut resistance / separation characteristics and cut penetration resistance when stepping on relatively dull projections and stepping on sharp projections. Excellent in cut and penetration resistance,
The purpose of the present invention is to provide a heavy-duty pneumatic radial tire mainly for running on a wasteland.

[0005]

The tire according to the present invention comprises:
A bead core provided on a pair of left and right bead parts, and a carcass consisting of a radial cord layer extending from one bead part to the other bead part and wound around the bead core and moored to the bead part. A pneumatic tire comprising a ply, a belt arranged radially outward of a crown portion of the carcass ply, and a tread, wherein: (1) the belt covers a plurality of substantially non-extensible cords; A rubber-laminated cord layer of at least three layers embedded in the tire is laminated so that the cord angle at the equator line of the tire is 5 to 40 degrees with respect to the circumferential direction so that the cords may cross each other between adjacent layers. (2) The maximum cross-sectional width of the main cross-belt layer is 7 times the cross-sectional width of the tread.
0 to 85%, and (3) two layers of at least three belt layers forming the main cross belt layer have a narrow width having a sectional width of 50 to 65% of the maximum width of the main cross belt layer. A belt layer, wherein the cord angle of the two narrow belt layers is 5 to 15 degrees with respect to the circumferential direction, and (4) one of the two narrow belt layers is the main cross belt layer. Any n-th belt layer that forms the first belt layer located on the innermost side in the radial direction, and the other one except the first belt layer and the second belt layer located adjacent to the first belt layer and located on the outer side in the radial direction. (5) the cord angle θ1 of the first belt layer is smaller than the cord angle θn of the nth belt layer, and
The cord angle θ n of the belt layer is smaller than the cord angles of the main cross belt layers other than the first and n-th belt layers,
(6) The sectional width W1 of the first belt layer and the sectional width Wn of the nth belt layer are smaller than the sectional widths of the main cross belt layers other than the first and nth belt layers. Pneumatic radial for heavy loads, which is mainly used for running on wastelands.
Tires.

As used herein, the term "main cross belt layer" means a plurality of rubber-coated cord layers formed by embedding a plurality of substantially inextensible cords in a coated rubber, and cords of adjacent layers. Means a belt layer in which the cord angle at the equator line of the tire is 5 to 40 degrees with respect to the circumferential direction so as to intersect with each other. The belt of the heavy duty pneumatic radial tire according to the present invention may be composed of only the main cross belt layer described above, but if necessary, a protective belt layer for protecting the main cross belt layer on the outer side in the radial direction. May be laminated. The function of the main cross belt layer is to bear the tension in the circumferential direction caused by the filling internal pressure of the tire and maintain the cross section of the tire in a desired shape. Therefore, a plurality of substantially non-extensible cords are covered with rubber. A plurality of rubber-coated cord layers embedded in the tire are laminated so that the cord angles at the equator line of the tire are 5 to 40 degrees with respect to the circumferential direction so that the cords of the adjacent layers intersect with each other.

In a conventional tire, when the protrusions such as rocks and crushed stones are stepped on, the tension applied to the outer layer of the belt is increased due to the input locally applied to the tire, and the cut-through resistance when the sharp protrusions are stepped on. Is reduced. However, in the tire of the present invention, as described above, two of the plurality of belt layers forming the main cross belt layer have a narrow width having a sectional width of 50 to 65% of the maximum width of the main cross belt layer. In the belt layer, the cord angle of the two narrow belt layers is 5 to 15 degrees with respect to the circumferential direction, and one of the two narrow belt layers is on the innermost side in the radial direction of the main cross belt layer. Forming the first belt layer located and the cord angle of this first belt layer being smaller than the cord angles of the other main cross belt layers,
The tension of the belt outer layer portion is relatively lowered, and the cut-through resistance when a sharp protrusion is stepped on is improved. Since the innermost belt layer in the radial direction has the largest degree of tension load due to the internal pressure, in the tire of the present invention, the cord angle of the first belt layer is smaller than the cord angles of the other main cross belt layers as described above. ing.

In the tire of the present invention, as described above, the two narrow belt layers are narrow belt layers having a cross-sectional width of 50 to 65% of the maximum width of the main cross belt layers. Since it is smaller than the cross-sectional width of the main cross belt layers other than the narrow belt layer, the belt easily bends in the width direction when stepping on the protrusions, and it is difficult to bend in the circumferential direction. The belt tension is not increased while ensuring the characteristics. When the width of the narrow belt layer is smaller than 50% of the maximum width of the main cross belt layer, the ability to bear the tension is insufficient, and the cut-through penetration resistance when stepping on a sharp protrusion is deteriorated. On the other hand, when the width of the narrow belt layer is larger than 65% of the maximum width of the main cross belt layer, the envelope power characteristic for wrapping the protrusions, whether sharp or dull, is deteriorated. Further, in the tire of the present invention, as described above, the cord angle of the first belt layer is smaller than the cord angle of the second belt layer which is adjacent to the first belt layer and is located on the outer side in the radial direction. , Second
If the cord angle of the belt layer is made as small as the cord angle of the first belt layer, the interlaminar shear strain between the first belt layer and the second belt layer becomes large and the belt durability is reduced, so avoid this. This is because

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A tire according to an embodiment of the present invention will be described with reference to the drawings. FIGS. 1 to 3 show an arrangement of belt layers of a pneumatic radial tire for truck according to an embodiment of the present invention. In a schematic half-section, the tire size is 275 / 80R22.5,
Is a pneumatic radial vehicle for a construction vehicle according to an embodiment of the present invention.
A left half cross-sectional schematic diagram showing the arrangement of the belt layers of the tire, the tire size is 37.00R57. A tire of Example 1 according to the present invention shown in FIG. 1 includes a bead core (not shown) provided in a pair of left and right bead portions, and a bead core extending from one bead portion to the other bead portion and wound around the bead core. A carcass ply (not shown) made of a radial cord layer and moored to the bead portion, and a belt B arranged on the outer side in the radial direction of the crown portion of the carcass ply.
Pneumatic radial with truck and tread T
Tires. Belt B is formed only of a main cross belt layer formed by laminating three layers of rubber-coated cords 1B, 2B and 3B in which a plurality of substantially inextensible steel cords are embedded in a coated rubber. Has been done. The maximum cross-sectional width Wb of the main cross belt layer is 170 mm, which is 81% of the cross-sectional width Wt (210 mm) of the tread T. The cross-sectional widths of the three belt layers 1B, 2B and 3B forming the main cross belt layer are 100 mm, 170 mm and 1 respectively.
Since it is 00 mm, the maximum width Wb of the main intersecting belt layers is 170% in the two layers of the belt layer 1B and the belt layer 3B among the three layers.
a narrow belt layer having a cross sectional width of 59% of mm,
Of the two narrow belt layers 1B and 3B, one belt layer 1B forms the first belt layer located on the innermost side in the radial direction of the main cross belt layer, and the other belt layer 3B forms the third belt layer. Is forming. The cord angle θ1 of the first belt layer 1B is 10 ° to the right with respect to the circumferential direction, and the second belt layer 2B
And the cord angle θ3 of the third belt layer 3B is 15 ° to the right with respect to the circumferential direction. Here, right and left indicate that they are arranged in the direction of rising to the right and the direction of rising to the left, respectively. Therefore, the cord angle θ1 of the first belt layer 1B is smaller than the cord angle θ3 of the third belt layer 3B, and the third belt layer 3
The cord angle θ3 of B is smaller than the cord angle of the main cross belt layers other than the first and third belt layers 1B and 3B (that is, the cord angle θ2 of the second belt layer 2B).

The tire of Example 2 has four rubber-coated cord layers 1B, 2B, 3B and 4B in which the belt B has a plurality of substantially inextensible steel cords embedded in the coated rubber. The main cross belt layers formed by laminating are formed, and the maximum cross sectional width Wb of the main cross belt layers is 175 mm, which is 83% of the cross sectional width Wt (210 mm) of the tread T.
Then, the cross-sectional widths of the belt layers 1B, 2B and 4B are 90 mm, 175 mm and 140 mm, respectively. Of the four layers, the two layers of the belt layer 1B and the belt layer 3B are respectively,
It is a narrow belt layer having a cross sectional width of 51% and 57% with a maximum width Wb = 175 mm of the main cross belt layer, and the cord angle θ1 of the first belt layer 1B is 5 ° to the right with respect to the circumferential direction.
The cord angle θ3 of the third belt layer 3B is 1 to the left with respect to the circumferential direction.
The tire is substantially the same as the tire of Example 1 except that the cord angle θ4 of the fourth belt layer 4B is 5 degrees and is 25 degrees to the right with respect to the circumferential direction.

The tire of Example 3 has belt layers 1B and 3B.
The cross-sectional widths of 4 and 4B are 105 mm and 140, respectively.
mm and 90 mm, two of the four layers, the belt layer 1B and the belt layer 4B, are narrow belt layers having a cross sectional width of 60% and 51% of the maximum width Wb = 175 mm of the main cross belt layer, respectively. , The code angle θ1 of the first belt layer 1B is 5 degrees left with respect to the circumferential direction, the code angle θ2 of the second belt layer 2B is 25 degrees right with respect to the circumferential direction, and the third belt layer 3
The tire is substantially the same as the tire of Example 2 except that the cord angle θ3 of B is 20 degrees left with respect to the circumferential direction and the cord angle θ4 of the fourth belt layer 4B is 15 degrees right with respect to the circumferential direction.

The tire of Conventional Example 1 has belt layers 1B and 2B.
And 3B have cross-sectional widths of 175 mm and 155, respectively.
mm and 125 mm, 100%, 89% and 71% of the maximum width of the main cross belt layer Wb = 175 mm, respectively.
%, The maximum width of the main cross belt layer is Wb = 175 mm
No narrow belt layer having a cross-sectional width of 50 to 65% is provided, the cord angle θ1 of the first belt layer 1B is 25 ° to the right with respect to the circumferential direction, and the cord angle θ2 of the second belt layer 2B is circumferential. On the other hand, it is the same as the tire of Example 1 except that it is 20 degrees left and the cord angle θ3 of the third belt layer 3B is 21 degrees right with respect to the circumferential direction. In the tire of Comparative Example 1, the belt layer 3B has a cross-sectional width of 100 mm, which is 57% of the maximum width Wb of the main cross belt layer = 175 mm.
The tire is the same as the tire of Conventional Example 1 except that the cord angle θ3 is 12 degrees to the right with respect to the circumferential direction.

A tire according to a fourth embodiment of the present invention shown in FIG. 4 is a bead core (not shown) provided on a pair of left and right bead portions, and a bead core extending from one bead portion to the other bead portion. A construction comprising a carcass ply (not shown) wound around the rope and moored to the bead portion, which is composed of a radial cord layer, and a belt B and a tread T arranged radially outside the crown portion of the carcass ply. Pneumatic radial tire for vehicle with tire size 37.00R57. Belt B is a main cross belt layer formed by laminating four rubber-coated cord layers 1B, 2B, 3B and 4B, each of which is formed by embedding a plurality of substantially inextensible steel cords in a coated rubber. The protective belt layer is composed of a single rubber-coated cord layer 5B formed by embedding a plurality of highly extensible steel cords in a coated rubber. The main cross belt layer is a layer having a function of mainly bearing the circumferential tension generated by the filling internal pressure of the tire, and the protective belt layer is a layer having a function of protecting the main cross belt layer from external damage. The maximum cross-sectional width Wb of the main cross belt layer is 620 mm, and the cross-sectional width Wt of the tread T is
It is 74% of (840 mm). The cross-sectional widths of the four belt layers 1B, 2B, 3B and 4B forming the main cross belt layer are 390 mm, 620 mm and 550 mm, respectively.
And 360 mm, the belt layer 1B out of the four layers
And the belt layer 4B are the maximum width Wb of the main cross belt layer.
A narrow belt layer having a cross-sectional width of 63% and 58% of 620 mm, the two narrow belt layers 1B and 4
One of the belt layers 1B of B forms the first belt layer located on the innermost side in the radial direction of the main cross belt layer, and the other belt layer 4B forms the fourth belt layer. The cord angle θ1 of the first belt layer 1B is 10 degrees to the right with respect to the circumferential direction,
The cord angle θ2 of the second belt layer 2B is 2 to the left with respect to the circumferential direction.
At 3 °, the cord angle θ3 of the third belt layer 3B is 20 ° to the right in the circumferential direction, and the cord angle θ4 of the fourth belt layer 4B is 15 ° to the left in the circumferential direction. Here, right and left indicate that they are arranged in the direction of rising to the right and the direction of rising to the left, respectively. Therefore, the cord angle θ1 of the first belt layer 1B is smaller than the cord angle θ4 of the fourth belt layer 4B,
Moreover, the cord angle θ4 of the fourth belt layer 4B is the cord angle of the main cross belt layers other than the first and fourth belt layers 1B and 4B (that is, the cord angle θ2 of the second belt layer 2B and the cord angle θ3 of the third belt layer 3B). The relationship is smaller than the code angle θ 3). The cord angle θ5 of the layer 5B forming the protective belt layer is 22 ° on the left and the cross-sectional width is 720 mm.

In the tire of Example 5, the cross-sectional widths of the belt layers 3B and 4B are 360 mm and 550 mm, and the two layers of the belt layers 1B and 3B among the four layers have the maximum width Wb of the main cross belt layer. It is a narrow belt layer having a cross-sectional width of 620 mm of 58%, the code angle θ3 of the third belt layer 3B is 15 degrees to the right in the circumferential direction, and the code angle θ4 of the fourth belt layer 4B is left to the circumferential direction. The tire is almost the same as the tire of Example 4 except that it is 20 degrees.

The tire of Example 6 has belt layers 1B and 3B.
And 4B have cross-sectional widths of 320 mm and 330, respectively.
mm and 500 mm, two of the four layers, the belt layer 1B and the belt layer 3B, are narrow belt layers having cross-sectional widths of 52% and 53% of the maximum width Wb of the main cross belt layer = 620 mm, respectively. , The code angle θ1 of the first belt layer 1B is 5 degrees to the right in the circumferential direction, the code angle θ3 of the third belt layer 3B is 15 degrees to the left in the circumferential direction, and the code angle θ4 of the fourth belt layer 4B is the circumferential direction. The tire is almost the same as the tire of Example 5 except that it is 20 degrees to the right.

The tire of Conventional Example 2 has belt layers 1B, 2
The cross sectional widths of B, 3B and 4B are 560 m, respectively.
m, 620 mm, 550 mm and 480 mm, respectively, with a maximum width Wb of the main cross belt layer Wb = 620 mm of 90
%, 100%, 89% and 77%, the maximum width Wb of the main cross belt layer is Wb = 620 mm and the narrow belt layer having a cross-sectional width of 50 to 65% is not provided, and the cord angle of the first belt layer 1B is θ1 is 22 degrees to the right with respect to the circumferential direction, the second
The cord angle θ2 of the belt layer 2B is 22 ° left with respect to the circumferential direction, the cord angle θ3 of the third belt layer 3B is 22 ° with respect to the circumferential direction, and the cord angle θ4 of the fourth belt layer 4B is left with respect to the circumferential direction. The tire is the same as the tire of Example 4 except that it is 22 degrees. In the tire of Comparative Example 2, the belt layer 4B has a cross-sectional width of 340 mm and the main cross belt layer has a maximum width Wb = 620.
55% of mm, code angle θ of the fourth belt layer 4B
The tire is the same as the tire of Conventional Example 2 except that 4 is 11 degrees to the left with respect to the circumferential direction.

Tires of Examples 1 to 3 and Conventional Example 1 and truck tires of Comparative Example 1, tires of Examples 4 to 6 and Conventional Example 2 and Comparative Example 2
In order to test the construction vehicle tires in comparison,
Tests were conducted on the separation characteristics, the cut-through penetration resistance when stepping on a relatively dull projection, and the cut-through penetration resistance when stepping on a sharp projection. Cut / separation characteristics are measured by inserting a cut that reaches the belt in the center of the tread of each test tire, and measuring the length of separation after running for a certain time under the conditions of normal internal pressure and load with an indoor drum tester. And to compare. The cut-through resistance when hitting a blunt protrusion is as follows: Each test tire is assembled into a regular rim with regular internal pressure, and a hemispherical protrusion with a diameter of about 15% of the tread width is pressed against the tire. Is a plunger test in which the strength of the tire is broken by breaking the tire, and the breaking energy is calculated and evaluated from the load at the time of breaking and the depth at which the protrusion bites into the tire. The cut-through resistance when stepping on a sharp protrusion is as follows.
This is a test for investigating the cut resistance of the tread of a tire using a regular triangular prism-shaped cutter having a width of about 15% of the tread width, and is evaluated by the energy before breaking.
The test results are shown in Table 1 (truck tires) and Table 2 (construction vehicle tires) in index notation with the result of the tire of the conventional example being 100. Higher numbers indicate better results.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

From the results shown in Tables 1 and 2, according to the present invention, cut resistance / separation characteristics, cut resistance when stepped on a relatively dull projection, and cut resistance when stepped on a sharp projection. It has become possible to provide a heavy-duty pneumatic radial tire that has excellent penetration characteristics, mainly for running on rough terrain.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of the left half showing the arrangement of a belt layer of a tire of the present invention.

FIG. 2 is a schematic sectional view of the left half showing the arrangement of the belt layers of the tire of the present invention.

FIG. 3 is a schematic sectional view of the left half showing the arrangement of the belt layers of the tire of the present invention.

FIG. 4 is a schematic sectional view of the left half showing the arrangement of the belt layers of the tire of the present invention.

FIG. 5 is a schematic sectional view of the left half showing the arrangement of the belt layers of the tire of the present invention.

FIG. 6 is a schematic sectional view of the left half showing the arrangement of the belt layers of the tire of the present invention.

[Explanation of symbols]

 1B 1st belt layer (main cross belt layer) 2B 2nd belt layer (main cross belt layer) 3B 3rd belt layer (main cross belt layer) 4B 4th belt layer (main cross belt layer) 5B 5th belt layer ( Protective belt layer) B Belt layer T Tread Wb Cross section width of main cross belt layer Wt Tread width

Claims (1)

[Claims] 1. A bead core provided on a pair of left and right bead portions, and a radial cord extending from one bead portion to the other bead portion, wound around the bead core and anchored to the bead portion. Carcass ply consisting of layers,
A pneumatic tire comprising a belt and a tread arranged radially outward of a crown portion of the carcass ply, wherein (1) the belt has a plurality of substantially inextensible cords embedded in a coated rubber. A main cross belt layer formed by laminating at least three rubber-coated cord layers formed by the above method so that the cords intersect with each other between adjacent layers so that the cord angle at the equatorial line of the tire is 5 to 40 degrees with respect to the circumferential direction. (2) the maximum cross-sectional width of the main cross belt layer is 70 to 85% of the cross-sectional width of the tread, and (3) at least three of the three belt layers forming the main cross belt layer.
The layer is a narrow belt layer having a cross-sectional width of 50 to 65% of the maximum width of the main cross belt layer, and the cord angle of the two narrow belt layers is 5 to 15 degrees with respect to the circumferential direction. Yes,
(4) One of the two narrow belt layers forms a first belt layer located on the innermost side in the radial direction of the main cross belt layer, and the other forms the first belt layer and the first belt layer. Forming an arbitrary nth belt layer excluding the second belt layer which is adjacent and located on the outer side in the radial direction, (5) the code angle θ 1 of the first belt layer is smaller than the code angle θn of the nth belt layer, And the cord angle θn of the nth belt layer is smaller than the cord angles of the main intersecting belt layers other than the first and nth belt layers, and (6) the cross-sectional width W1 of the first belt layer and the nth belt layer. A heavy-duty pneumatic radial tire mainly used for running on rough terrain, characterized in that the belt layer has a cross-sectional width Wn smaller than that of the main cross belt layers other than the first and n-th belt layers.