JP2003326914A - Pneumatic radial tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic radial tire which supports reduction in rolling resistance, improvement of tire motion performance and lowered price and can improve waterproof high-speed durability and workability at rubber coating. <P>SOLUTION: This pneumatic radial tire comprises a plurality of first steel element wires for which a steel chord 8 of a belt layer 7 is formed and aligned, and a second steel element wire 10 formed and arranged around its outer circumference side. The diameters d1 and d2 of the first and the second steel element wires 9 and 10 are 0.15 to 0.40 mm, forming widths h1 and h2 are h1=1.2d1 to 5.0d1, h2=1.2d2 to 5.0d2, and forming pitch λ1 and λ2 are 3.0 to 20.0 mm. The second steel element wire 10 has the winding pitch P of 40 to 100 mm and wound around the outer circumference of the first steel element wire 9 in the spiral state. <P>COPYRIGHT: (C)2004,JPO

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 pneumatic radial tire which is improved in water resistance and high speed durability and workability during rubber coating.

[0002]

2. Description of the Related Art In recent years, pneumatic radial tires, especially pneumatic radial tires for passenger cars, have been used in belt layers in response to market needs such as reduction of rolling resistance (fuel efficiency), improvement of tire dynamic performance, and price reduction. The development of the steel cord to be used is progressing.

As part of this, instead of the conventional twisted cord, a non-twisted steel cord formed by aligning a plurality of steel strands and one steel strand further spirally wound around the outer circumference of the steel cord. Steel cords with different configurations have been proposed.

However, since the steel strands of these cords are not twisted with each other, the shape stability of the cords is poor, and as a result, the spacing between the steel strands is increased by the cord tension applied in the step of coating the rubber. It easily closes and the permeability of rubber to the steel cord deteriorates. Therefore, the corrosion fatigue resistance of the steel wire decreases,
Water resistance High-speed durability is adversely affected. In addition, the workability is unavoidably deteriorated because the steel wires are likely to disperse during rubber coating.

On the other hand, there is also a proposal of a so-called long pitch steel cord in which the twist pitch is significantly increased as compared with the conventional one. However, there is still a problem that the steel wires forming the steel cord are scattered, and improvement in the shape stability of the cord cannot be expected so much.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to reduce rolling resistance, improve tire dynamic performance, and reduce cost while improving water resistance and high speed durability and workability during rubber coating. It is to provide a pneumatic radial tire.

[0007]

Means for Solving the Problems The present invention, which achieves the above object, is to provide a steel cord extending obliquely in the tire circumferential direction on the outer peripheral side of the carcass layer in the tread portion at a predetermined interval in the tire circumferential direction. In a pneumatic radial tire in which a belt layer arranged inside is arranged, the steel cord is
It is composed of a plurality of first steel strands which are shaped and aligned at a predetermined pitch and a second steel strand which is arranged on the outer peripheral side thereof and which is shaped at a predetermined pitch. The diameter d1 of the first steel strand. And the diameter d2 of the second steel wire is 0.15 to 0.40 mm, respectively, and the molding width h1 of the first steel wire and the molding width h2 of the second steel wire.
Where h1 = 1.2d1 to 5.0d1 and h2 = 1.2d2 to
5.0d2, the pitch for forming the first steel wire λ1
And a pitch for forming the second steel wire λ2 is 3.0 to 20.0 mm, and a pitch for winding the second steel wire is 40 to 100 mm. It is characterized by being wound into a shape.

By thus constructing the steel cord of the belt layer from the first steel strand and the second steel strand defined as described above, the steel strands bite into each other and it is difficult for the steel strands to disperse. Shape stability is increased, and as a result, workability in coating rubber can be improved.

Further, since it becomes difficult to close the interval between the steel wires, it is possible to facilitate the permeation of rubber into the steel cord, so that the corrosion resistance of the steel wires is improved and the water resistance high speed durability is enhanced. be able to. Since the No. 1 steel wire has an aligned structure without being twisted, it responds to market needs such as reduced rolling resistance, improved tire dynamic performance, and lower prices in the same way as steel cords using the conventional aligned structure. can do.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The configuration of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an example of a pneumatic radial tire of the present invention, in which 1 is a tread portion, 2 is a sidewall portion, 3 is a bead portion, and CL is a tire center line.

A carcass layer 4 is mounted between the left and right bead portions 3, and both ends 4a of the carcass layer 4 are sandwiched around a bead core 5 embedded in the bead portion 3 from the inside of the tire to the outside thereof. It is folded back. Tread section 1
On the outer peripheral side of the carcass layer 4, two belt layers 7 in which steel cords 8 that are inclined and extend in the tire circumferential direction are arranged in the rubber layer G at predetermined intervals in the tire circumferential direction are arranged.

The steel cord 8 is, as shown in FIG.
Non-twisted multiple (N
The first steel strand 9 and one spirally shaped second steel strand 10 arranged on the outer peripheral side of the first steel strand 9 have an N + 1 structure.

The diameter d1 of the first steel wire 9 and the diameter d2 of the second steel wire 10 are 0.15 to 0.4, respectively.
It is in the range of 0 mm. Also, the first steel wire 9
Width h1 of the second steel wire 10 and width h2 of the second steel wire 10
Is h1 = 1.2d1 to 5.0d1, h2 = 1.2d2
It is set to ~ 5.0d2. Further, as shown in FIG. 3, the molding pitch λ 1 of the first steel wire 9 and the molding pitch λ 2 of the second steel wire 10 are 3.0 to 20.
It is set in the range of 0 mm.

The second steel element wire 10 shaped as described above is spirally wound around the outer circumference of the plurality of first steel element wires 9 aligned with the winding pitch P of 40 to 100 mm. .

According to the present invention described above, the steel cord 8 of the belt layer 7 is constituted by the first steel wire 9 and the second steel wire 10 specified as described above, whereby the steel wire 9, Since it is difficult for the 10 pieces to bite into each other, it is possible to improve the shape stability of the cord and thus improve the workability when coating the rubber.

Further, since it becomes difficult to close the interval between the steel wires, it is possible to enhance the rubber permeability into the steel cord 8, and as a result, the corrosion fatigue resistance of the steel wires is improved and the water resistance and high speed durability are improved. The sex can be improved.

Moreover, since the first steel strands 9 are not twisted but have the aligned structure, it is possible to meet market needs such as reduction of rolling resistance, improvement of tire dynamic performance, and price reduction.

If the diameters d1 and d2 of the steel strands 9 and 10 are less than 0.15 mm, the belt flexural rigidity is lowered and the water resistance high speed durability and steering stability (tire dynamic performance) are deteriorated. On the other hand, if it exceeds 0.40 mm, the strain applied to the steel wire becomes too large and belt breakage occurs, resulting in deterioration of water resistance, high speed durability.

Molding widths h1 and h of the steel wires 9 and 10
When 2 is smaller than 1.2d1 or 1.2d2, the rubber permeability is lowered and the water resistance and high speed durability are deteriorated. On the other hand, if it is larger than 5.0d1 or 5.0d2, the expansion and contraction of the steel cord 8 becomes too large and the tensile strength of the belt is lowered. The embossing widths h1 and h2 are preferably h1
= 1.5d1 to 3.0d1, h2 = 1.5d2 to 3.0
It should be d2.

Molding pitch λ1 of steel wires 9 and 10
, Λ2 is less than 3.0 mm, the belt tensile rigidity decreases, and conversely, if it exceeds 20.0 mm, the rubber permeability deteriorates.

If the winding pitch P of the second steel wire 10 is less than 40 mm, the tensile strength of the belt is lowered due to the reduction of the tension share of the second steel wire 10, and conversely 100
If it is larger than mm, the shape stability of the cord is lowered and the rubber permeability is deteriorated.

In the present invention, it is preferable to form the steel wires 9 and 10 of the steel cord 8 in a spiral shape as described above, because it is possible to increase the amount of bite between the steel wires and to prevent the steel wires from becoming more uneven. However, it may be shaped in a wavy shape or the like as long as it is shaped at a predetermined pitch.

The number N of the first steel wires 9 is 2
It can be ~ 6. When the number N is one, the impact damping characteristic of the cord is deteriorated because the contact points between the wires are lost, and the steering stability performance and riding comfort performance are deteriorated. On the other hand, if the number exceeds 6, the permeability of rubber into the cord will be reduced.

The above-mentioned steel cord 8 ensures the biting of the steel wires 9 and 10 with each other, and in order to make the diameters of the steel cords 8 uniform, the second steel wire 10 is wound and then rolled. It is preferable to make a flat cord having a flat cross section by applying.

The present invention can be preferably used for a pneumatic radial tire for passenger cars, but is not limited thereto.

[0027]

EXAMPLE Inventive cords 1 and 2 in which the tire size is common to 195 / 60R14 and the structure of the steel cord of the belt layer is as shown in Table 1, and the inventive tire 1 having the configuration shown in FIG. 2 (Examples 1 and 2), comparison code 1
8 to Comparative tires 1 to 8 (Comparative Examples 1 to 8), the steel cord of the belt layer has a twist structure, and the twist pitch is 60.
A so-called long pitch conventional cord 1 having a long length of mm, a conventional tire 1 (conventional example 1) using the same, and a non-twisted conventional cord 2 formed by aligning unshaped steel strands and the cord are used. Conventional tire 2 (Conventional example 2)
And were produced respectively.

The total weight of the steel cord of the belt layer in each test tire was the same. Further, the comparative tire 1 has the diameters d1 and d2 of the first and second steel wires smaller than the range of the present invention (less than 0.15 mm), and the comparative tire 2 has the diameters d1 and d2 larger than the range of the present invention. (0.
40 mm), the comparative tire 3 has the first and second steel wire molding widths h1, h2 smaller than the range of the present invention (less than 1.2d1 and less than 1.2d2), and the comparative tire 4 has The widths h1 and h2 were made larger than the range of the present invention (greater than 5.0d1 and more than 5.0d2), and the comparative tire 5 had the first and second steel element wire forming pitches λ1 and λ2.
Is smaller than the range of the present invention (less than 3.0 mm), the comparative tire 6 has a molding pitch λ1, λ2 larger than the range of the present invention (more than 20.0 mm), and the comparative tire 7 is the second steel strand. The winding pitch P of the comparative tire 8 is smaller than the range of the present invention (less than 40 mm), and the winding pitch P of the comparative tire 8 is larger than the range of the present invention (100 mm).
Super).

Each of these test tires was subjected to an evaluation test of water resistance, high speed durability and steering stability by the following test method, and the results shown in Table 1 were obtained.

When each test cord was subjected to an evaluation test of the variability of the cord as an alternative test of the workability at the time of rubber coating, the results shown in Table 1 were obtained. Water resistance and high-speed durability Each test tire was tested in an atmosphere of 70 ° C and 95% humidity.
Rim size 14 x 6 after left for months to deteriorate in water resistance
It is attached to the JJ rim, the air pressure is set to 230 kPa, and it is attached to the drum tester, and the diameter is 170 under the condition of the load of 5 kN.
Running on a rotating drum of 7 mm at an initial speed of 121 km / h, increasing the speed by 8 km / h every 30 minutes, and measuring the running distance until the tire fails. The result is an index with Conventional Example 1 as 100. It was evaluated by. The larger this value, the better the water resistance and high speed durability. Steering stability Each test tire was mounted on a rim with a rim size of 14 × 6JJ, mounted on a front-wheel drive passenger car with a displacement of 1.8 liters, with an air pressure of 230 kPa, and was trained by five trained test drivers on the test course. A ring test was performed, and the results were evaluated by each test driver on a 10-point scale, and the average value (rounded to one decimal place) was shown. The larger this value, the better the steering stability. Variation of code The variation of the code when the terminal portion of each test code was cut with pliers was evaluated according to the following four criteria.

1: A state in which each test cord has a cut end held by a hand and cut with pliers, and this is repeated three times, and the test cord disperses once or more. Cut with pliers in the same manner as 2: 1 and repeat this 3 times, and it is not distorted 3 times. 3: Each test code is in a state in which a portion 50 mm away from the cut end of each test cord is held by hand and cut with pliers, and in that state there is no discontinuity in the cut end, but a slight tap causes it to dissipate. As with 4: 3, cut with pliers and tapped lightly to keep it in place. The larger this value is, the more difficult it is to disperse, and thus the workability at the time of rubber coating is excellent.

[0032]

[Table 1] It can be seen from Table 1 that the tire of the present invention can improve the water resistance and high speed durability and the workability at the time of rubber coating while ensuring the same level of steering stability as the conventional tire.

[0033]

As described above, according to the present invention, a plurality of first steel strands obtained by shaping and aligning steel cords,
The second steel element wire is wound around the outer peripheral side in a spiral shape, and the diameter of the first and second steel element wires, the forming width, the forming pitch, and the winding pitch of the second steel element wire are as described above. By satisfying the requirements such as reduction of rolling resistance, improvement of tire dynamic performance, and price reduction, it is possible to improve water resistance and high-speed durability and workability during rubber coating.

[Brief description of drawings]

FIG. 1 is a half sectional view of a tire meridian showing an example of a pneumatic radial tire of the present invention.

FIG. 2 is an enlarged cross-sectional view showing an example of a steel cord used in the belt layer of FIG.

FIG. 3 is a side view of an essential part showing one of the steel wires of FIG. 2 as viewed from the side of FIG.

[Explanation of symbols]

1 Tread Part 2 Sidewall Part 3 Bead Part 4 Carcass Layer 5 Bead Core 6 Bead Filler 7 Belt Layer 8 Steel Code 9 1st Steel Element Wire 10 2nd Steel Element Wire CL Tire Centerline G Rubber Layer d1, d2 Diameter h1, h2 Molding width λ1, λ2 Molding pitch

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Naoki Kanehira             2-1, Oiwake, Hiratsuka-shi, Kanagawa Yokohama Rubber Co., Ltd.             Ceremony Company Hiratsuka Factory F term (reference) 3B153 AA11 AA12 AA13 AA19 AA24                       AA43 AA46 BB13 CC52 FF16                       GG05 GG07 GG13 GG40

Claims (7)

[Claims] 1. A pneumatic radial tire in which a belt layer in which steel cords extending obliquely in the tire circumferential direction are arranged in a rubber layer at a predetermined interval in the tire circumferential direction is arranged on the outer peripheral side of the carcass layer of the tread portion. In the above, the steel cord is composed of a plurality of first steel strands that are modeled at a predetermined pitch and are aligned, and a second steel strand that is modeled at a predetermined pitch and is arranged on the outer peripheral side thereof. The diameter d1 of one steel wire and the diameter d2 of the second steel wire are 0.15 to 0.40 m, respectively.
m, the shaping width h1 of the first steel strand and the shaping width h2 of the second steel strand are h1 = 1.2d1 to 5.0.
d1 and h2 = 1.2d2 to 5.0d2, the molding pitch .lamda.1 of the first steel wire and the molding pitch .lamda.2 of the second steel wire are 3.0 to 20.0 mm, respectively.
Also, the second steel strand is wound around and the pitch is 40 to 10
A pneumatic radial tire having a length of 0 mm and spirally wound around the outer circumference of the first steel strand. 2. The molding widths h1 and h2 are set to h1 = 1.5d.
The pneumatic radial tire according to claim 1, wherein 1 to 3.0d1 and h2 = 1.5d2 to 3.0d2. 3. The pneumatic radial tire according to claim 1, wherein the first steel wire and the second steel wire are shaped in a spiral shape. 4. The pneumatic radial tire according to claim 1, wherein the first steel wire and the second steel wire are wavy shaped. 5. The pneumatic radial tire according to claim 1, wherein the steel cord is formed into a flat cord having a flat cross section by rolling. 6. The pneumatic radial tire according to claim 1, wherein the plurality of first steel strands is 2 to 6. 7. The pneumatic radial tire according to claim 1, wherein the second steel strand is one.