JP4628080B2 - Heavy duty pneumatic radial tire - Google Patents

Description

  The present invention relates to a heavy-duty pneumatic radial tire that is suitable for use mainly in trucks, buses, construction vehicles, and the like, and is particularly intended to effectively increase the durability of a belt.

  Pneumatic radial tires applied to heavy-duty vehicles such as trucks, buses, and construction vehicles generally have a main crossing belt layer embedded with thick steel cords arranged at a relatively large inclination angle with respect to the circumferential direction of the tire. Two or more small inclined belt layers arranged inside the main crossing belt layer and arranged at a small inclination angle with respect to the circumferential direction of the tire, and arranged outside the main crossing belt layer, with respect to the circumferential direction of the tire A belt structure in which cords arranged at a large inclination angle are embedded and a protective layer wider than the main crossing belt layer is employed (see, for example, Patent Document 1).

  JP 2002-362109 A

  In the conventional belt of this type, all adjacent cords are arranged in the opposite direction to the tire circumferential direction in order to ensure the rigidity in the circumferential direction and the width direction of the tire. To ensure the rigidity (transverse rigidity, in-plane bending rigidity) against deformation along the belt, bear the tension in the tread circumferential direction by the small inclined belt layer, suppress the tread diameter growth and change the crown shape during running It has a function-separated belt structure that prevents the damage and breakage of each layer due to the protrusion input from the road surface by the protective layer.

  By the way, in heavy-duty vehicles, such as construction vehicles, vehicles that are used severely on the input surface, such as running on uneven road surfaces, cutting input, etc. There was a major breakdown.

  For example, as shown in FIG. 1, the rubber cracks from the widthwise end position A of the widest layer of the protective layers, which is the width of the widest layer of the main crossing belt layers. Gradually end B and advance toward the inner peripheral side of the tire at a higher speed from the width end B (in the tread width direction starting from the width direction end position A of the widest layer of the protective layer) In this case, when the angle α with respect to the line segment drawn in the direction is set to the angle α, the angle α progresses at an angle of 15 to 20 °).

  The other is, as shown in FIG. 2, a crack occurs in the width direction end of the belt having the narrowest width in the main crossing belt layer, and this crack propagates between the belt layers constituting the main crossing belt layer (the main crossing belt layer). The crossing belt layer group has a function to ensure the lateral rigidity and in-plane bending rigidity of the tire, and it is set to be wider than the high angle layer arranged inside, so when it receives a large input, it is the main crossing A case in which the deformation in the width direction of the belt with the narrowest width of the belt layer is greatly deformed and shear strain occurs, and a crack generated from the position propagates between the layers), resulting in separation and failure. In either case, it has been a cause of hindering the extension of the tire life.

  An object of the present invention is to propose a heavy-duty pneumatic radial tire that improves the durability of the belt and can extend the life of the tire in order to solve the above-described problems of the conventional technology.

The present invention includes a steel radial car mosquito scan made by arranging at least one carcass ply into a toroidal, a steel belt of plural layers disposed on the outer peripheral side of the steel radial carcass,
The steel belt is
At least one layer made more consisting placed scan steel cord just above the steel radial carcass, makes cord angle of 4 to 10 ° with the tire circumferential direction, the small slant belt layer has a width of 22 to 45% of a product tire width When,
At least consists of a pair, form code angles 18 to 35 ° with the circumferential direction of the tire, main cross belt layers have a width of 55 to 72% of a product tire width thereof consisting placed scan steel carcass cord upwards Layers,
A protective layer comprising at least a pair of high elongation steel cords disposed above the cord, the cord angle with the circumferential direction of the tire being 22 to 33 °, and a width of 60 to 82% of the product tire width; Consists of
In the heavy-duty pneumatic radial tire in which the small inclined belt layer, the main crossing belt layer, and all adjacent layers forming the protective layer have a cord direction opposite to the tire circumferential direction,
When the width of the minimum width layer of the layer forming the protective layer is X, the width of the minimum width layer of the layer forming the main crossing belt layer is Y, and the width of the maximum width layer is Z, The width X of the minimum width layer is wider than the width Y of the minimum width layer of the main crossing belt layer, and the X / Y relationship is 105% ≦ X / Y ≦ 112%, and
A heavy-duty pneumatic radial tire characterized in that the width X of the minimum width layer of the protective layer does not exceed the width Z of the maximum width layer of the main crossing belt layer.

In the heavy-duty pneumatic radial tire configured as described above, the end A of the maximum width layer of the main crossing belt layer and the end B of the maximum width layer of the protective layer are along the width direction of the tire. Having a separation distance d1 of 90-120 mm,
The angle θ formed by the straight line connecting the points A and B and the horizontal line in the width direction of the tire is preferably 0 to 15 °.

  The width X of the minimum width layer of the protective layer is made wider than the width Y of the minimum width layer of the main crossing belt layer, and the X / Y relationship is set to 105% ≦ X / Y ≦ 112%. By making the width X of the minimum width layer not to exceed the width Z of the maximum width layer of the main crossing belt layer, the development of rubber cracks starting from the width direction end position of the widest layer of the protective layer Separation between layers in the main crossing belt layer is suppressed.

Hereinafter, the present invention will be described more specifically with reference to the drawings.
FIG. 3 is a cross-sectional view in the width direction of a tread portion showing a half portion of a tire in which a heavy-duty pneumatic tire according to the present invention is mounted on an applicable rim and filled with a specified air pressure, and FIG. 4 shows a belt plane. It is a figure.

  Here, the applicable rim and the prescribed air pressure refer to a standard determined by an industrial standard effective in the region where the tire is produced or used (for example, “JATMA YEAR BOOK” of the Japan Automobile Tire Association, "STANDAEDS MANUAL" from THE TIRE and RIM ASSOCIATION Inc. in the United States or "STANDARDS MANUAL" from The European Tire and Rim Technical Organization in Europe).

  In the figure, reference numeral 1 denotes a steel radial carcass in which carcass plies are disposed in a toroidal manner between bead cores (not shown), and 2 denotes a steel belt composed of a plurality of layers disposed outside the carcass 1.

  This steel belt 2 is composed of two layers having a high-strength steel cord disposed immediately above the steel radial carcass 2. The cord angle formed with the tire circumferential direction is 4 to 10 °, and the product tire width W (product tire width). Refers to the pattern or character on the side of the tire from the straight distance (total width) between the side walls including all the pattern or character on the side of the tire that is loaded with the specified air pressure and filled with the specified air pressure Of the small inclined belt layers 2a and 2b having the widths W1 and W2 of 22 to 45% and the high-tensile steel carcass cords disposed thereon, and the circumferential direction of the tire. The main crossing belt layers 2c and 2d having an angle of 18 to 35 ° with each layer having a width W3 and W4 of 55 to 72% of the product tire width W, and further disposed above Protective layers 2e and 2f having a pair of high elongation steel cords placed thereon, the cord angle with the circumferential direction of the tire being 22 to 33 °, and the widths W5 and W6 of 60 to 82% of the product tire width For all adjacent layers forming the small inclined belt layers 2a, 2b, the main crossing belt layers 2c, 2d and the protective layers 2e, 2f, the direction of the cord is opposite to the tire circumference. It is arranged to be. Reference numeral 3 denotes a tread rubber disposed outside the steel belt 2.

In the tire having the above-described configuration , the width W6 of the minimum width layer 2f among the layers forming the protective layers 2e and 2f is wider than the width W4 of the minimum width layer of the main crossing belt layers 2c and 2d, and is W6 / W4. The relationship is 105% ≦ X / Y ≦ 112%, and the width W6 of the minimum width layer 2f of the protective layers 2e and 2f does not exceed the width W5 of the maximum width layer 2c of the main crossing belt layers 2c and 2d. It has become.

  The end A of the maximum width layer 2c of the layers forming the main crossing belt layers 2c and 2d and the end B of the maximum width layer 2e of the protective layers 2e and 2d are 90 to 90 along the tire width direction. The distance d1 is set to 120 mm, and the angle θ between the straight line L connecting the points A and B and the horizontal line H in the width direction of the tire is set to 0 to 15 °.

  In the present invention, the width W6 of the minimum width layer 2f of the layers forming the protective layers 2e and 2f is wider than the width W4 of the minimum width layer of the main crossing belt layers 2c and 2d, and the relationship of W6 / W4 is 105%. ≦ X / Y ≦ 112%, and the width W6 of the minimum width layer 2f of the protective layers 2e and 2f is set not to exceed the width W5 of the maximum width layer 2c of the main crossing belt layers 2c and 2d. The reason is that if these conditions are not satisfied, the protective layers 2e, 2d can be used to suppress movement in the tire circumferential direction at the width ends of the main crossing belt layers 2c, 2d when the tire receives a large input. Is wider as compared to the small inclined belt layers 2a, 2b and the main crossing belt layers 2c, 2d, but instead, at the width ends of the protective layers 2e, 2f, the tire circumferential direction, the width direction The deformation in the case becomes large, and cracks occur at the width end of the protective layer 2f. Raw, this crack leads to a failure of the tire and causes a decrease in tire life. The tendency is that the width W6 of the protective layer 2f, which is the smallest of the protective layers 2e and 2f, is the main crossing belt. When the width W3 of the main crossing belt layer 2c, which is the maximum width of the layers 2c and 2d, is exceeded, the restraint force is lost at the width end of the protective layer 2f, and the deformation becomes large, and the increase in cracks at the width end is further increased. This is because it becomes prominent.

  In the present invention, the end A of the maximum width layer 2c of the layers forming the main crossing belt layers 2c and 2d and the end B of the maximum width layer 2e of the protective layers 2e and 2d are the width of the tire. The distance d1 is set to 90 to 120 mm along the direction, and the angle θ between the straight line L connecting the points A and B and the horizontal line M in the width direction of the tire is set to 0 to 15 ° for the following reason. It is.

  If the separation distance d1 is less than 90 mm, the width direction of the main crossing belt layer 2c having the maximum width may be close to the crack propagation direction, whereas if it exceeds 120 mm, the width of the protective layer 2e becomes too wide. Shear strain becomes excessive and cracks are more likely to occur.

  By setting the separation distance d1 in the range of 90 to 120 mm, the width of the main crossing belt layer 2c having the maximum width is sufficiently separated from the distance and from the width end of the protective layer 2e having the maximum width. Thus, it is possible to suppress an increase in the crack growth rate.

  When the angle θ formed by the straight line L connecting the points A and B and the horizontal line M of the tire is 0 ° to 15 °, if the angle θ is less than 0 °, the protective layers 2e and 2f are too close to the carcass ply and are protected. Cracks having the fulcrums of the layers 2e and 2f reach the carcass ply and easily cause a failure. On the other hand, when the angle exceeds 15 °, the width end of the main crossing belt layer 2c having the maximum width becomes too close to the crack propagation path. It will be.

  A straight line L connecting an end A of the maximum width layer 2c of the layers forming the main crossing belt layers 2c and 2d, an end B of the maximum width layer 2e of the protective layers 2e and 2d, and a horizontal line M of the tire in the width direction; By making the angle θ formed by 0 to 15 °, the main crossing bell and the width end of 2c can be sufficiently separated from the progress direction of the crack extending from the width end of the protective layer 2e, and the crack propagation speed is increased. It can prevent speeding up.

  Since the tire according to the present invention progresses in the state shown in FIG. 5 and does not go through the width end of the main crossing belt layer 2c even if a crack occurs, the progress speed does not increase.

6-layer belt structure as shown in Table 1 (2a to 2f are displayed as 1B to 6B from the inside to the outside, and the belt angle R is ascending to the right when the belt layer is viewed in plan, and L is ascending to the left. Tires (maximum width of 1300mm) with size 53 / 80R63, which are embedded in regular rims (TRA standard) and filled with regular internal pressure (TRA standard), then 150% LOAD is added. Drum straight running durability test (run for 200 hours). After the test, each tire was cut and dissected at four places on the circumference, and the belt width end (width end of the minimum width layer of the protective layer (6B), main crossing belt layer) The occurrence of cracks at the width edge (4B) of the minimum width layer was investigated. The results are shown in Table 2, and the results of Table 2 are graphed in FIG.
In Table 2, CONTROL4B end crack length is set to 100.

  As apparent from Table 2 and FIG. 6, the tire according to the present invention has a reduced crack length at the width end of 4B, and it was confirmed that the tire life can be extended.

7-layer belt structure as shown in Table 3 (indicated from 1B to 7B from the inside to the outside, the belt angle R means a right-up when the belt layer is viewed in plan, and L means a left-up) Each tire (maximum width 1470mm) of size 59 / 80R63 is manufactured and incorporated into a regular rim (TRA standard) and filled with regular internal pressure (TRA standard), and then 150% LOAD is added and a straight running durability test for the drum is performed. After running the test, each tire was cut and dissected at four locations on the circumference, and the width of the belt (the width of the minimum width of the protective layer (7B), the width of the minimum width of the main crossing belt layer) The state of occurrence of cracks at the width edge (5B) was investigated. The results are shown in Table 2, and the results of Table 2 are graphed in FIG.
In Table 2, CONTROL5B end crack length is set to 100.

  As apparent from Table 4 and FIG. 7, the tire according to the present invention has a reduced crack length at the width end of 5B, and it was confirmed that the tire life can be extended.

8 to 11 show another embodiment of the tire according to the present invention.
FIG. 8 shows a size 4000R57 having a belt structure of 6 layers (applicable rim: 29.00 / 6.0, product tire width: 1100 mm, internal pressure: 700 kPa), and belt widths and angles as shown in Table 5 were set. At this time, the 6B width / 4B width is 108%, and the angle θ is 5 °. Further, the tire having the structure as shown in FIG. 9 is set to the belt width and angle as shown in Table 6. At this time, the 6B width / 4B width is 107% and the angle θ is 7 °.

FIG. 10 shows a belt width and cord angle as shown in Table 7 in a size 53 / 80R63 (applicable rim: 36.00 / 5.0, product tire width: 1300 mm, internal pressure: 600 kPa) having a seven-layer belt structure. In this case, the 7B width / 5B width is 109%, and the angle θ is 13 °. Further, the tire having the structure as shown in FIG. 11 having a 6-layer belt structure can be set to the belt width and angle as shown in Table 8, and at this time, the 6B width / 4B width is 107%, angle θ is Ru 14 ° der.

  By improving the belt durability, it is possible to stably supply a heavy-weight pneumatic radial tire with an extended tire life.

It is the figure which showed typically the generation | occurrence | production state of the crack about the cross section of the conventional belt structure. It is the figure which showed typically the generation | occurrence | production state of the separation about the cross section of the conventional belt structure. It is the figure which showed embodiment of the tire according to this invention. It is the figure which showed the plane of the belt of the tire shown in FIG. It is the figure which showed the progress condition of the crack of the tire according to this invention. It is the figure which showed the relationship between crack length and 6B / 4B. It is the figure which showed the relationship between crack length and 7B / 5B . It is the figure which showed the belt structure of the tire according to this invention. It is the figure which showed the belt structure of the tire according to this invention. It is the figure which showed the belt structure of the tire according to this invention. It is the figure which showed the belt structure of the tire according to this invention.

Explanation of symbols

1 Steel radial carcass 2 Steel belt 3 Tread rubber

Claims (2)

Comprising a steel radial car mosquito scan made by arranging at least one carcass ply into a toroidal, a steel belt of plural layers disposed on the outer peripheral side of the steel radial carcass,
The steel belt is
At least one layer made more consisting placed scan steel cord just above the steel radial carcass, makes cord angle of 4 to 10 ° with the tire circumferential direction, the small slant belt layer has a width of 22 to 45% of a product tire width When,
At least consists of a pair consisting of arranged scan steel cord in its upper, forms the code angles 18 to 35 ° with the circumferential direction of the tire, the main intersecting belt layers each layer having a width of 55 to 72% of a product tire width When,
A protective layer comprising at least a pair of high elongation steel cords disposed above the cord, the cord angle with the circumferential direction of the tire being 22 to 33 °, and a width of 60 to 82% of the product tire width; Consists of
In the heavy-duty pneumatic radial tire in which the small inclined belt layer, the main crossing belt layer, and all adjacent layers forming the protective layer have a cord direction opposite to the tire circumferential direction,
When the width of the minimum width layer of the layer forming the protective layer is W6, the width of the minimum width layer of the layer forming the main crossing belt layer is W4, and the width of the maximum width layer is W3, The width W6 of the minimum width layer is wider than the width W4 of the minimum width layer of the main crossing belt layer, and the relationship of W6 / W4 is 105% ≦ W6 / W4 ≦ 112%, and
A heavy-duty pneumatic radial tire characterized in that the width W6 of the minimum width layer of the protective layer does not exceed the width W3 of the maximum width layer of the main crossing belt layer. The end A of the maximum width layer of the layers forming the main crossing belt layer and the end B of the maximum width layer of the protective layers have a separation distance d1 of 90 to 120 mm along the tire width direction. And
2. The heavy-duty pneumatic radial tire according to claim 1, wherein an angle θ formed by a straight line connecting the points A and B and a horizontal line in the width direction of the tire is 0 to 15 °.