JP2001225618A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a steel code reinforcing layer from being separated in a radial-directional outer end in an outside area, and to prevent a bead part from being rubbed with a rim. SOLUTION: This tire is provided with a radial carcass 3 arranged to be wound up from an inside to an outside in a periphery of a bead core 2 and comprising a steel code ply, a steel code reinforcing layer 4 arranged ranging over from a tire width-directional inside area to its outside area in a periphery of the bead core 2, a chafer rubber 5 arranged in a contact area contacting with the wheel rim, and a sidewall rubber 6 joined layeredly onto the chafer rubber 5. The radial-directional outer ends A, B of the tire in a portion existing respectively in the tire width-directional outside and inside areas of the reinforcing layer 4 are positioned respectively within 25-40 deg. and 50-70 deg. of angle ranges with respect to a horizontal line segment h passing through a curvature center O using as a reference the curvature center O of a rim flange RF in the rim R, under an attitude where air pressure is filled after assemble to the rim R, in a condition where 100% modulus of the chafer rubber 5 is brought into 02.8-5.0 MPa and where 100% modulus of the sidewall rubber 6 is brought into 1.5-2.7 MPa.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire, and more particularly to a heavy-duty tire applied to off-the-road vehicles such as industrial vehicles and construction vehicles. While preventing, the steel cord reinforcement layer arranged in the bead part,
It is intended to effectively prevent separation of a so-called wire chafer at an outer end portion in a tire radial direction.

[0002]

2. Description of the Related Art In a radial tire of this kind applied to other off-the-road vehicles of industrial vehicles, when a large load or a lateral force acts on the bead portion under the use condition of the tire, the bead portion is changed to the tire. The rim is deformed in the direction of falling outward in the width direction and repeatedly contacts the radially outer end portion of the rim flange of the wheel rim, so that the rim is easily rubbed there.

Conventionally, as shown in FIG. 2, one tire bead portion of a rim-assembled tire filled with air pressure is surrounded by a single bead around a bead core 22 disposed on a bead portion 21 as shown in a cross section in the tire width direction. The radial carcass 23 made of the steel cord ply is wound up from the inner side to the outer side in the tire radial direction, and is arranged around the bead core 22 from the inner area to the outer area in the tire width direction. One or more steel cord reinforcing layers 24 circumscribing 23, in other words, a wire chafer, are disposed, and the radial outer end A of the steel cord reinforcing layer 24 existing in the outer region in the tire width direction is trimmed. Horizontal line segment h passing through the center of curvature of flange RF
And the radial outer end B of the steel cord reinforcing layer 24 existing in the inner region in the tire width direction is 25 to 3 with respect to the horizontal line segment h.
5 ° and the bead portion 21
Chafer rubber 25 disposed in the contact area with the rim R
Is laminated and joined to the sidewall rubber 26 on the outer surface side of the tire.

According to this, the steel cord reinforcing layer 24
In particular, since the outer end A in the outer region radial direction is located at a sufficiently high position to advantageously restrain the bead portion from falling down as described above, it is possible to effectively avoid occurrence of rim rubbing on the bead portion. Can be.

[0005]

However, in such a conventional technique, the outer end A of the steel cord reinforcing layer 24 in the outer region in the radial direction is set too high, so that the radially outer end A of the steel cord reinforcing layer 24 is located at a location where the deformation is large. Since the outer end A exists, there is a problem that separation easily occurs there.

If the outer end A in the radial direction is set too low, the circumferential deformation area of the bead portion 21 reaches the inside in the radial direction, so that rim rubbing on the bead portion 21 is effectively prevented. There was a problem that it could not be prevented.

On the other hand, by joining the chafer rubber 25 to the outer surface side of the sidewall rubber 26, there is a problem that cracks due to rim abrasion easily occur in the high hardness chafer rubber 25.

Accordingly, the present invention can sufficiently prevent separation of the steel cord reinforcing layer at the radially outer end of the outer region, and can also effectively prevent rim rubbing of the bead portion.
More preferably, the present invention provides a pneumatic radial tire that can also advantageously prevent the occurrence of rim rubbing cracks on a bead portion.

[0009]

According to the pneumatic radial tire of the present invention, a radial carcass composed of one or more steel cord plies is wound around a bead core from the inside to the outside in the tire radial direction, and is arranged. ,
One or more steel cord reinforcement layers, also around the bead core, from the inner area to the outer area in the tire width direction, adjacent to the radial carcass, and the contact area of the bead part with the wheel rim And the side wall rubber disposed from the buttress portion to the bead portion are joined together at the bead portion under a mutual lamination, so that the 100% modulus of the chafer rubber is 2.8.
When the 100% modulus of the sidewall rubber is 1.5 to 2.7 MPa, the steel cord reinforcing layer is mounted on the rim and filled with air pressure in the tire width direction. The tire radial outer end of the portion present in each of the outer region and the inner region, based on the center of curvature of the rim flange of the wheel rim,
25-40 ° and 50-
It is located in each angle range of 70 °.

[0010] Here, "rim" means JATMA YE.
AR BOOK means the applicable rim specified in the
"Air pressure" means JATMA YEAR BOO
It means the maximum air pressure which is the air pressure corresponding to the maximum load capacity specified in K.

According to this, in particular, the radial outer end of the outer region of the steel cord reinforcing layer is set at a distance of 2 to the horizontal line segment.
By being located within the angle range of 5 to 40 °, the outer end height is greatly reduced as compared with the related art, so that the separation of the radial outer end of the steel cord reinforcing layer and the vicinity thereof can be effectively performed. Lack of circumferential shear stiffness due to lowering the outer end height, on the other hand, may result in the inner radial outer end of the steel cord reinforcement layer being horizontal relative to the horizontal line segment. It can be compensated for by being positioned within the angle range of 50-70 ° and by increasing the outer end height sufficiently compared to the prior art. Accordingly, as a result, the risk of rim rubbing of the bead portion can be effectively removed while preventing the separation of the steel cord reinforcing layer.

[0012] More preferably, in such a tire, the sidewall rubber is laminated on the tire outer surface side with respect to the chafer rubber, and the inner end of the sidewall rubber in the tire radial direction is more radially inner than the outer end of the chafer rubber in the tire radial direction. Preferably, the inner end of the sidewall rubber in the tire radial direction is arranged at a position where the bead portion is separated from the rim flange in a no-load state in which the rim-assembled tire is filled with air pressure.

According to the former, the high hardness chafer rubber, which is liable to cause cracks due to rim rubbing, is covered with the sidewall rubber having excellent rim rubbing cracking resistance, so that the cracks are advantageously generated. Can be prevented.

According to the latter, the radially inner end position of the sidewall rubber, which can be selected as appropriate,
By specifying the position where the bead portion is separated from the rim flange, it is possible to effectively prevent a decrease in the bead portion rigidity and, consequently, the occurrence of cracks due to the reduction.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view in the tire width direction showing one bead portion of a tire in a state in which an embodiment of the present invention is assembled on a rim and filled with air pressure, where 1 is a bead portion, 2 is a bead portion, and FIG. A bead core having a hexagonal cross-sectional profile arranged in part 1
Reference numeral 3 denotes a radial carcass made up of one or more steel cord plies, which is wound around the bead core 2 from the inside to the outside in the tire radial direction and disposed.

The steel cord ply of the radial carcass 3 can be wrapped around the bead core 2 from the inside to the outside in the tire width direction or in the opposite direction, or the radial carcass 3 One ply in the former direction and the other ply in the latter direction.

Here, one or more steel cord reinforcing layers 4 are arranged around the bead core 2 from the inner side to the outer side in the width direction of the tire so as to circumscribe the radial carcass 3. The outer end A in the tire radial direction of the portion existing in the widthwise outer region of the layer 4 is attached to the rim R under a tire attitude filled with air pressure, with the center of curvature O of the rim flange RF as a reference. Is located radially outward in the tire range within an angle range of 25 to 40 ° with respect to a horizontal line h passing through, and a radially outer end B of a portion of the steel cord reinforcing layer 4 existing in the inner region.
Is similarly positioned within an angle range of 50 to 70 ° with respect to the horizontal line h.

Further, in this case, the contact area of the bead portion 1 with the rim R has a 100% modulus of 2.8 to 5.0.
The chafer rubber 5 in the range of MPa is arranged along the steel cord reinforcing layer 4 from the inner region to the outer region in the tire width direction, and the 100% modulus is in the range of 1.5 to 2.7 MPa. Wall rubber 6
Is disposed from the buttress portion to the bead portion, and the radially inner end portion of the sidewall rubber 6 is laminated and joined to the chafer rubber 5 on the outer surface side of the tire. The radially inner end of the rubber 6 is disposed at a position C where the bead portion 1 is separated from the rim flange RF in the unloaded state of the rim-assembled tire filled with air pressure, as shown in the figure.

In the figure, reference numeral 7 denotes a beadillar disposed on the outer peripheral side of the bead core 2 between the main body portion and the winding portion of the radial carcass 3, and 8 and 9 respectively denote the steel cord reinforcing layer 4. Shows an organic fiber cord cover layer covering the radially outer end B of the tire width direction inner area, wherein one organic fiber code cover layer 8 directly circumscribing the steel cord reinforcing layer 4 is a width direction outer area. Extend over a wide range up to the width-wise outer region so as to cover the radially outer end A.

According to the pneumatic radial tire configured as described above, in particular, the steel cord reinforcing layer 4
By specifying the respective outer ends A and B in the tire radial direction of the portions existing in the outer region and the inner region in the tire width direction as described above, the outer ends A and B of the steel cord reinforcing layer 4 and Rim abrasion of the bead portion 1 can be effectively prevented without occurrence of separation near the outer end.

In addition, here, the side wall rubber 6 is laminated and joined to the chafer rubber 5 on the outer surface side of the tire, and the radially inner end of the side wall rubber 6 is separated from the bead portion 1 from the rim flange RF. Position C
With this arrangement, the occurrence of cracks due to rim rubbing can be advantageously prevented by the sidewall rubber 6, and the rigidity of the bead portion can be kept high.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example tire having an ORR 16.00 R25 and having a bead structure shown in FIG. 1 and a conventional tire having a bead structure shown in FIG. The rim was assembled with the rim and filled with air pressure of 900 kPa, and was subjected to a load of 16.5 ton by an indoor drum tester.
After running at a speed of 0 km / h for 192 hours (3840 km), the presence or absence of separation of the steel cord reinforcing layer, the rim abrasion resistance and the rim abrasion crack resistance were examined. Was.

The evaluation of the rim rub resistance and the rim rub resistance was carried out every 24 hours (480 km).
It was performed by checking the size and depth of the rim scratches and cracks. The larger the index value in the table, the better the results.

[0024]

[Table 1]

According to Table 1, it can be seen that in the example tire, both the separation resistance and the rim rub resistance are effectively improved.

[0026]

As is apparent from the above description, according to the present invention, in particular, the radially outer end of the outer region of the steel cord reinforcing layer is appropriately reduced as compared with the prior art. By appropriately increasing the radially outer end of the inner region as compared with the prior art, it is possible to effectively prevent rim rubbing of the bead portion without separation of the steel cord reinforcing layer.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view in the tire width direction showing an embodiment of the present invention for one bead portion.

FIG. 2 is a cross-sectional view in the tire width direction showing a conventional example with respect to one bead portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bead part 2 Bead core 3 Radial carcass 4 Steel cord reinforcement layer 5 Chafer rubber 6 Sidewall rubber A, B Outer end C Position R Rim RF Rim flange O Center of curvature h Horizontal line

Claims (3)

[Claims] 1. A bead core, a radial carcass made of a steel cord ply wound and disposed around the bead core from the inside to the outside in the tire radial direction, and a bead core and an outside from an inner region in a tire width direction around the bead core. A steel cord reinforcement layer disposed adjacent to the radial carcass, a chafer rubber disposed in the contact area of the bead portion with the wheel rim, and a bead portion disposed from the buttress portion to the bead portion. A sidewall rubber laminated and joined to the chafer rubber, and the 100% modulus of the chafer rubber is 2.8 to
A pneumatic radial tire having a side wall rubber with a 100% modulus of 1.5 to 2.7 MPa at 5.0 MPa, wherein the steel cord reinforcing layer is mounted on a rim and filled with air pressure. The tire radially outer end of the portion present in each of the tire width direction outer side region and the inner side region is located at 25 to 40 ° and 50 to 50 ° with respect to a horizontal line passing therethrough with reference to the center of curvature of the rim flange of the wheel rim. 70 °
Pneumatic radial tires located in the respective angle ranges. 2. The pneumatic radial tire according to claim 1, wherein the sidewall rubber is laminated on the outer surface side of the tire with respect to the chafer rubber. 3. The tire according to claim 1, wherein the inner end of the sidewall rubber in the tire radial direction is disposed at a position where the bead portion is separated from the rim flange in a no-load state in which the rim-assembled tire is filled with air pressure. Pneumatic radial tire.