JPH0642307U - Radial tires for heavy loads - Google Patents

Abstract

(57) [Abstract] [Purpose] It is intended to provide a heavy duty radial tire in which the occurrence of cracks at the side marking base is suppressed by controlling the marking position of the side marking. [Structure] In a heavy-duty radial tire that engraves side markings on the sidewall surface, the engraving prohibited area of the side marking is set from the rim flange height RL to the height h ₁ outward in the tire radial direction to increase the height of the engraving prohibited area. H ₁
Rim flange height R, which is the range of large tensile strain
More than 0.09h and less than 0.29h from L (0.09h <h ₁ <0.29
By setting it in the range of h), the starting point of crack generation disappears, crack generation is suppressed, and structural durability and rehabilitation are improved.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a heavy-duty radial tire that is used in a heavy vehicle such as a large truck and receives a large load.

[0002]

[Prior art]

 Recently, the proportion of radial tires in tires used for heavy vehicles such as large trucks is increasing, but the structural characteristics of radial tires are that the vertical rigidity of the side wall is lower than that of bias tires. However, the amount of deformation of the side wall to approach the equilibrium state during inflation is large, and the side wall is further deformed when the load rolls under load, and this tendency tends to occur in tires with low flatness. It is even more prominent. Conventionally, side markings such as brand name, tread pattern name, tire size, maximum internal pressure, load, tire material, tubeless, etc. have been engraved in an embossed manner in place on the sidewall of a tire. Due to the deformation, there is a problem that cracks are likely to occur at the base portion of the side marking, that is, the transition portion between the side marking and the sidewall.

In order to solve the above problem, for example, JP-A-61-184101 discloses that a tire flatness is 0.65 or less, and a relief-shaped side marking is provided in an annular region directly below a buttress portion on a sidewall surface. At the base of the side marking, a fillet (shaping part) is provided at the transition part from the protruding part to the side wall surface so that the cross-section has a curvature, and the cross-section curvature of the fillet is the outermost position in the tire radial direction. The radius of the cross-section contour curve of the inner fillet in the radial direction is 0.1 to 0.4 mm, and the radius of the cross-section contour curve of the fillet is the outermost position in the radial direction of the tire. Is 1.5 times or more of the inner side to prevent stress concentration on the outermost site marking base in the radial direction of the tire, that is, side marking of the outermost side in the tire radial direction. Since stress concentration on the part is large small illusion curvature of the cross section profile curve of the fillet, the pneumatic radial tire has a size comb curvature of the cross section profile curve of the fillet from the stress concentration is small in inner is described.

[0004]

[Problems to be solved by the device]

 However, as specified in JIS standard, normal side markings, except for brand name and tread pattern name, must be engraved on the bead side, that is, the tire radial direction inner side than the tire maximum width position. With conventional pneumatic radial tires, no measures were taken for side marking other than the brand name and tread pattern name, and inflating from the tire maximum width position to the bead portion caused deformation due to inflation. There is a tendency that tensile strain is generated on the side wall surface and cracks are easily generated on the bead side base of the side marking, and this crack may have a serious adverse effect on structural durability and rehabilitation. there were.

An object of the present invention is to provide a heavy-duty radial tire in which the occurrence of cracks in the side marking base is suppressed by controlling the marking position of the side marking.

[0006]

[Means for Solving the Problems]

The radial tire for heavy loads of the present invention is a radial tire for heavy loads in which side markings are engraved on the sidewall surface. The engraving prohibited area for prohibiting engraving of the side markings is located outward from the rim flange height RL in the radial direction of the tire. By setting it to h ₁ and setting the range of height h ₁ of the marking prohibited area to more than 0.09h and less than 0.29h (0.09h <h ₁ <0.29h) from the rim flange height RL, cracks will occur. It is possible to improve the structural durability and rehabilitation property by eliminating the starting point of cracks and suppressing the occurrence of cracks.

[0007]

【Example】

 An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a heavy duty radial tire to which the present invention is applied. The radial tire 1 includes a tread 2 and a belt layer 3, and the tread 2 and both ends of the tread 2 are extended radially inward. It consists of a one-ply steel cord that penetrates through a pair of side walls 4 and is wound from the inside to the outside around a bead core 6 embedded in a bead portion 5 formed at the inner end of the side wall 4. The carcass 7 has a carcass 7. The winding end 71 of the carcass 7 ends at a position lower than the upper end of a substantially triangular bead apex 8 extending radially outward from the bead core 6, that is, a position radially inward. . Further, a chafer 9 made of steel cord is arranged outside the winding portion of the carcass 7 so that both ends thereof are located at positions radially inward of the winding end 71 of the carcass 7.

In FIG. 2, the magnitude of the tensile strain (hereinafter referred to as inflation strain) on the surface of the sidewall caused by the air pressure when inflated is expressed as the radial direction outward from the rim flange height RL of the rim 10. When measured according to the height, in a tire having a height h between the rim flange height RL and the tire outer diameter, it is small in the vicinity of the tire maximum width height h _{m and in} the vicinity of the rim 10, and is 0.09 from the rim flange height RL. It was found that the inflation strain exceeds 5% within the range of more than h and less than 0.29 h. It should be noted that such a distribution of the inflation strain becomes more remarkable as the tire internal pressure increases when the tire is mounted on a vehicle and a load is applied.

When the side marking is engraved in the range of more than 0.09h and less than 0.29h from the rim flange height RL with a large inflation strain, a crack is generated at the base of the side marking due to the inflation strain (tensile strain). To do. Therefore, the marking forbidden areas of the side marking set from the rim flange height RL to the height h ₁ in the tire half radially outward, the height h ₁ of the engraved prohibition area beyond 0.09h from the rim flange height RL By setting the range to be less than 0.29h (0.09h <h ₁ <0.29h), the starting point of crack generation disappears.

[0010] In tires of size 285 / 75R24.5, in the embodiment of the present invention engraved with side markings Except insofar engraved prohibition area h ₁ side marking, side marking within the scope of the engraved prohibition area h ₁ Using the comparative example marked with “2.D. D-4.4 was installed on a truck, a fixed load (36 t) was loaded, and a test was performed on an actual vehicle to check for the occurrence of cracks after running 100,000 km. There was no crack, and the tire of the comparative example cracked at the edge of the marking font.

[0011]

[Effect of device]

 Since the present invention is configured as described above, it has the following effects. By controlling the marking position of the side marking, the starting point of the crack generation can be eliminated, the crack generation at the side marking base can be suppressed, and the crack generation can be suppressed to improve the structural durability and rehabilitation property.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a heavy duty radial tire to which the present invention is applied.

FIG. 2 is a distribution diagram of inflation strain of a radial tire.

[Explanation of symbols]

1 radial tires, 2 treads, 3 belt layers, 4
Side wall 5 bead part, 6 bead core, 7 carcass, 8 bead apex 9 chafer, 10 rim, RL rim flange height

Claims (1)

[Scope of utility model registration request] 1. In a heavy-duty radial tire for engraving side markings on the sidewall surface, the engraving prohibited area of the side marking is set to a height h ₁ outward in the tire radial direction from the rim flange height, and the engraving prohibited area is set. The height h ₁ range of the rim flange exceeds 0.09h and the range is 0.
A heavy-duty radial tire characterized by having a length of less than 29 h (0.09 h <h ₁ <0.29 h).