JP2004322782A - Pneumatic radial tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic radial tire capable of attaining both a comfortable riding characteristic and a stable operating characteristic and in particular preferable for a passenger vehicle or a small-sized truck. <P>SOLUTION: This pneumatic radial tire 1 is constructed such that each of bead fillers 3, 3 is arranged at outer circumferential sides of a pair of right and left bead cores 2, 2, respectively, a carcass ply 5 having at least two layers composed of an organic fibrous cord C with a total denier of 4,400 dtex or less is mounted between the bead cores 3, 3 and a belt layer 7 is arranged at the outer circumference side of the carcass ply 5. A cord side clearance t between the carcass plies 5, 5 within a range R ranging from an end part 7a of the belt layer 7 to an upper end 3a of the bead filler 3 is set to be 0.9 to 3.0 times of a diameter d of the organic fibrous cord C. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pneumatic radial tire, and more particularly, to a pneumatic radial tire that is suitable for a passenger car or a small truck that achieves both riding comfort and steering stability.
[0002]
[Prior art]
In general, pneumatic radial tires for passenger cars or light trucks have an organic fiber cord used for the carcass layer, and there are those having two or more carcass layers, but it is difficult to obtain rigidity of the tire side portion, There was a limit to obtaining high steering stability using only the carcass layer. Conventionally, in order to improve this, a reinforcing layer is additionally provided on the side wall portion in addition to the carcass layer (see, for example, Patent Document 1), the height of the bead filler is increased, or the side wall portion is not provided. Attempts have been made to increase rigidity, such as by increasing the amount of rubber. However, none of these attempts has been sufficient to reduce riding comfort and increase tire weight.
[0003]
[Patent Document 1]
JP-A-2002-59715 (pages 1-6, FIGS. 1-3)
[0004]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic radial tire that solves the conventional problems and achieves both ride comfort and steering stability, and is particularly suitable for passenger cars or small trucks.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the pneumatic radial tire of the present invention has a bead filler disposed on the outer peripheral side of a pair of left and right bead cores, and at least two layers of an organic fiber cord having a total fineness of 4400 dtex or less between the bead cores. In a pneumatic radial tire in which a carcass layer is mounted and a belt layer is arranged on an outer peripheral side of the carcass layer, a cord side surface between the carcass layers at least in a range from an end of the belt layer to an upper end of the bead filler. The interval is set to 0.9 to 3.0 times the diameter of the organic fiber cord.
[0006]
As described above, since the cord side surface spacing between the carcass layers at least in the range from the end of the belt layer to the upper end of the bead filler is set to 0.9 to 3.0 times the diameter of the organic fiber cord of the carcass layer, the steering is performed. By increasing the lateral stiffness for improving the stability by increasing only a small amount of material, it is possible to improve the steering stability without reducing the riding comfort.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
[0008]
FIG. 1 is a half sectional view showing an example of a pneumatic radial tire for a passenger car according to the present invention. The pneumatic radial tire 1 has bead cores 2 and 2 buried in a pair of left and right bead portions 4 and 4, and bead fillers 3 and 3 are arranged on the outer peripheral side thereof. The ends of the carcass layers 5, 5 composed of two layers, inner and outer, respectively, are folded back on the bead cores 2, 2 so as to wrap the bead fillers 3, 3 from the inside of the tire to the outside. A belt layer 7 is disposed on the outer peripheral side of the carcass layer 5 of the tread portion 6.
[0009]
Each of the carcass layers 5 and 5 is made of an organic fiber cord C such as nylon having a total fineness of 4400 dtex or less, and is covered with rubber. The interlayer Q between the two carcass layers 5, 5 is thicker with a substantially uniform width than other regions at least in a range R from the end 7 a of the belt layer 7 to the upper end 3 a of the bead filler 3. As shown in FIG. 2, which is a cross section taken along the line XX in FIG. 1, the cord side space t with the thickness of the interlayer Q increased is 0.9 to 3.0 times the diameter d of the organic fiber cord C, preferably. Is adjusted to 1.2 to 2.4 times.
[0010]
If the cord side surface spacing t between the carcass layers in the region R is less than 0.9 times the diameter d of the organic fiber cord C, the effect of increasing the side portion rigidity cannot be obtained, and the purpose of improving maneuverability cannot be achieved. If it exceeds 0.0 times, the ride comfort will be reduced, and the carcass line will have a local change in the radius of curvature, and the durability will be reduced.
[0011]
The adjustment of the cord side surface distance t between the carcass layers as described above is usually performed by adjusting the thickness of the covering rubber covering the organic fiber cord C. Thereby, without causing delamination of the carcass layers 5, 5, the interlayer distance is widened, rigidity as a composite material is secured, and rigidity of the tire side portion is increased. The above-described expansion of the interlayer distance can be performed by inserting a sheet different from the rubber covering the carcass layer as described below.
[0012]
That is, as illustrated in FIG. 2, it can be performed by inserting a sheet 8 made of rubber or thermoplastic resin having a JIS hardness of 50 to 80, preferably 55 to 65 between the carcass layers 5 and 5. .
[0013]
In the present invention, the carcass layer is composed of at least two layers, but preferably two or three layers. If the number of layers is four or more, the rigidity itself increases and the weight increases, so that it is difficult to achieve the object of the present invention.
[0014]
When the carcass layer 5 is composed of three layers, the position between the layers for widening the cord side surface spacing is not particularly limited, but it is most preferable to configure the cord side surface spacing between the innermost layer and its outer layer as described above. In addition to this, the cord side gap with the outer layer may be simultaneously described above.
[0015]
The carcass cord is made of an organic fiber such as nylon or polyester, and the organic fiber cord used has a total fineness of 4400 dtex or less. In particular, a general-purpose 1100 dtex / 2 or 1670 dtex / 2 organic fiber cord is preferably used. When the total fineness is more than 4400 dtex, the organic fiber cord becomes too rigid and disadvantageous in terms of ride comfort. The lower limit is preferably 1500 dtex.
[0016]
The radial tire of the present invention configured as described above is particularly preferably applied as a tire for a passenger car, and can be applied to a light truck.
[0017]
Further, the above-described cord side surface interval t is at least between the end 7a of the belt layer 7 and the upper end 3a of the bead filler 3 so that the shape of the carcass layers 5 and 5 does not deviate from the ideal carcass line. It is preferable to make adjustments so as to be substantially equal in the range R.
[0018]
[Experimental example]
A tire size is 195 / 80R15 107/105 LLT and a fineness is 1670 dtex / 2. The cord side surface spacing t between the carcass layers 5 and 5 in the region R in the structure of FIG. As shown in FIG. 3, 15 different pneumatic radial tires were manufactured.
[0019]
When the steering stability and ride comfort were evaluated for these 15 types of pneumatic radial tires, the results shown in FIG. 3 were obtained.
[0020]
From FIG. 3, it can be seen that the steering stability and ride comfort are improved in a well-balanced manner by setting the cord side surface interval t between the carcass layers to 0.9 to 3.0 times the carcass cord diameter d.
[0021]
【The invention's effect】
As described above, the pneumatic radial tire of the present invention has a cord side surface interval between the carcass layers at least in the range from the end of the belt layer to the upper end of the bead filler, which is 0.9% of the diameter of the organic fiber cord of the carcass layer. Since it is 3.0 times, the steering rigidity can be improved without lowering the riding comfort by increasing the lateral rigidity for improving the steering stability by increasing only a small amount of material.
[Brief description of the drawings]
FIG. 1 is a half sectional view showing an example of a pneumatic radial tire of the present invention.
FIG. 2 is a sectional view taken along line XX of FIG.
FIG. 3 is a graph for explaining the results of an experiment performed to confirm the effects of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pneumatic radial tire 2 Bead core 3 Bead filler 4 Bead part 5 Carcass layer 6 Tread part 7 Belt layer 8 Sheet

Claims (3)

A bead filler is arranged on the outer peripheral side of the pair of left and right bead cores, and at least two carcass layers made of an organic fiber cord having a total fineness of 4400 dtex or less are mounted between the bead cores, and a belt is provided on the outer peripheral side of the carcass layer. In a pneumatic radial tire with layers arranged,
A pneumatic radial tire in which a space between cord side surfaces between the carcass layers at least in a range from an end portion of the belt layer to an upper end portion of the bead filler is 0.9 to 3.0 times a diameter of the organic fiber cord. 2. The pneumatic radial tire according to claim 1, wherein side intervals between cords between the carcass layers are made substantially uniform at least within a range from an end of the belt layer to an upper end of the bead filler. 3. The sheet according to claim 1 or 2, wherein a sheet made of rubber or a thermoplastic resin different from the covering rubber of the carcass layer is inserted between the carcass layers at least in a range from an end of the belt layer to an upper end of the bead filler. The described pneumatic radial tire.

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