JP2574152B2 - Pneumatic tire - Google Patents

Description

Description: TECHNICAL FIELD [0001] The present invention relates to a pneumatic tire having a belt reinforcing layer on a tread portion and having improved tire uniformity without impairing high-speed durability.

(Prior art)

When a belt layer made of a steel cord is arranged on a tread portion of a tire (for example, two layers), if a centrifugal force acts during high-speed running, the rigidity of the belt layer in a circumferential direction of the tire is insufficient and the tire is largely deformed and broken. Will be reached.

As a countermeasure against this, conventionally, a belt reinforcing layer made of a fiber cord such as nylon is arranged on the tread portion to enhance high-speed durability. In this belt reinforcing layer, the cords are arranged at substantially 0 ° (parallel) with respect to the tire circumferential direction, thereby preventing deformation in the radial direction due to centrifugal force. For example, in many cases, one belt reinforcing layer is disposed in a tire having a speed indication of H class (movable up to 210 km / h), and two belt reinforcing layers are disposed in higher performance tires.

However, a tire having such a belt reinforcing layer has a disadvantage that uniformity (UF) is deteriorated and riding comfort is impaired.

That is, in order to arrange the belt reinforcing layer, an unvulcanized calender material in which the fiber cords are arranged in parallel is prepared as shown in FIG.
As shown in (1), a splice portion 1 is formed by wrapping both ends of the belt layer around the belt layer in the circumferential direction of the tire. The green tire in an unvulcanized state thus formed is put into a mold, and the inner surface of the tire is inflated into a predetermined product shape (2-4% in a circumferential change rate). This expansion increases the circumference of the belt reinforcing layer. In this case, the cord angle of the belt reinforcing layer with respect to the tire circumferential direction is almost 0.
Since it is ゜ (parallel), the circumference is increased by reducing the amount of wrap by displacing the superposed layers in the splice part 1 as shown in FIG. 5 (B). When the superposed layers of the belt reinforcing layer are shifted from each other in the splice portion 1, the belt layer and the cap tread layer are deformed together. For this reason, the splice part 1 and other parts
The thickness of the material and the angle of the material vary, causing the product tire to be non-uniform on the circumference, resulting in poor uniformity.

[Object of the invention]

An object of the present invention is to provide a pneumatic tire having a belt reinforcing layer in a tread portion, which has improved uniformity without impairing high-speed durability.

[Configuration of the invention]

In order to achieve the above object, the present invention provides air in which a belt layer in which steel cords are inclined with respect to the tire circumferential direction and a belt reinforcing layer in which fiber cords are arranged are stacked and arranged outside the carcass layer of the tread portion. For tires containing
The belt reinforcing layer is disposed outside the belt layer, and the fiber cords of the belt reinforcing layer are arranged so as to be inclined with respect to the circumferential direction of the tire. While the inclination angle θ of the fiber cord of the belt reinforcing layer is set to 15 ° ± 5 °, the inclination direction is the same as that of the steel cord of the belt layer adjacent inside, and the belt reinforcing layer has The ratio of the width A to the width B of the belt layer is set to 1.12 to 1.18.

Hereinafter, the configuration of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an explanatory cross-sectional view in the meridian direction of an example of the pneumatic tire of the present invention, and FIG. 2 is an explanatory plan view of an essential part thereof.
In FIG. 1, a carcass layer 3 is mounted between a pair of left and right bead wires 2,2. In the tread portion 4, a belt layer 5 in which steel cords are arranged obliquely with respect to the tire circumferential direction EE 'is arranged on the carcass layer 3 so as to be annular in the tire circumferential direction. A belt reinforcing layer 6 made of a fiber cord such as an organic fiber such as an organic fiber or a carbon fiber or an inorganic fiber such as a glass fiber is annularly disposed in the tire circumferential direction.

The cord 6a of the belt reinforcing layer 6, as shown in FIG.
It is inclined with respect to the tire circumferential direction EE '. This code 6a
Is 15 ° ± 5 °. Belt layer 5
The cords 6a of the belt reinforcing layer 6 arranged on the outside are arranged in the same direction as the steel cords of the upper belt layer 5u adjacent on the inside in the same inclination direction, whereby the belt layers are arranged more than in the case where they are arranged in the opposite direction. Since the shearing force acting between 5u and the belt reinforcing layer 6 can be reduced and the occurrence of edge separation therebetween can be suppressed, higher speed performance can be obtained.

The width A of the belt reinforcing layer is set to be larger than the width B of the belt layer. That is, a belt reinforcing layer 6 laminated on a belt layer 5 on which steel cords are arranged and arranged outside the carcass layer 3 of the tread portion 4 extends in the tire width direction beyond both ends of the belt layer 5. The reason for this is that
Since the belt reinforcing layer terminal is locked in the rubber on the outer side of the belt layer, deformation generated in the belt layer at high speed can be suppressed by pulling resistance of the surrounding rubber against the cord of the belt reinforcing layer locked on the outer side of the belt layer. Because. The ratio of the width A of the belt reinforcing layer to the width B of the belt layer, that is, A / B
Is in the range of A / B = 1.12 to 1.18.

The belt reinforcing layer 6 may be provided in at least one layer. For example, as shown in FIG.
May be arranged in two layers. When two layers are arranged, a higher level of high-speed performance can be obtained as compared with the case of one layer. Further, as shown in FIG. 3 (B), a conventional belt reinforcing layer 7 having a cord angle parallel to the tire circumferential direction may be disposed on the belt reinforcing layer 6, but in this case, the uniformity improving effect is obtained. Decreases slightly. FIG. 3 (C)
As shown in (1), another reinforcing layer 8 may be arranged only on the width direction end (belt edge) of the belt reinforcing layer 6, and in this case, the reinforcing material, shape, angle, etc. are different from those of the belt reinforcing layer 6. May be.

 Examples will be described below.

Examples (1) Uniformity was evaluated for the following tires of the present invention and conventional tires.

(A) The tire of the present invention.

Tire for passenger car of size 185 / 60R14, belt reinforcement layer angle: 10 °, ratio of width A of belt reinforcement layer to width B of belt layer (A / B): 1.12.

(B) Conventional tire.

Tire for passenger car of size 185 / 60R14, belt reinforcement layer angle: 0 °, ratio of width A of belt reinforcement layer to width B of belt layer (A / B): 1.00.

Uniformity: UF waveform was measured based on JASO C 607 "Automobile tire uniformity test method". Regarding the RFV as a result, the conventional tire is shown in FIG.
These are shown in FIG. In the figure, C indicates a splice at the time of forming the belt reinforcing layer, and it can be seen that the conventional tire has a remarkable peak. Table 1 below shows the average values of the ten tires. From Table 1, it can be seen that the tires of the present invention are RFV, LFV
It turns out that both are excellent.

Table 1 RFV LFV Conventional tire 7.9 3.4 Tire of the present invention 5.3 1.7 (2) High-speed performance was tested by variously changing the inclination angle and width of the fiber cord of the belt reinforcing layer. The test was performed using an indoor drum tester, and the breaking speed was determined by increasing the speed by 10 km / h every 30 minutes. The results are shown in Table 2 below. In Table 2, the dashed line If the area enclosed by is a conventional tire, The portions surrounded by the circles indicate the case of the tire of the present invention.

As can be seen from Table 2, in the case of the conventional tire, a speed of about 10 km / h can be obtained as compared with the case where the belt reinforcing layer is not provided, but in order to improve uniformity, the belt reinforcing layer is simply added. However, when the angle is 20 °, the speed is not improved, so that the speed is reduced as compared with the case without the belt reinforcing layer. On the other hand, the tire of the present invention has a high speed of 200 km / h or more, and not only does not impair the high speed durability, but also can secure a higher high speed durability than before.

Table 3 shows an example of the high speed when the cord of the belt reinforcing layer and the steel cord of the belt layer are in the same inclined direction and in the opposite direction. The test conditions are the same as described above. In the table,-indicates that the cord of the belt reinforcing layer and the steel cord of the belt layer are in opposite directions.

From Table 3, it is possible to obtain higher high-speed durability when the inclination direction of the fiber cords of the belt reinforcing layer disposed outside the belt layer is the same as that of the steel cord of the belt layer adjacent to the inside thereof. I understand.

[Effects of the Invention] As described above, the present invention laminates a belt layer in which steel cords are arranged inclined with respect to the tire circumferential direction and a belt reinforcing layer in which fiber cords are arranged outside the carcass layer of the tread portion. In the pneumatic tire, the belt reinforcing layer is disposed outside the belt layer, and the fiber cords of the belt reinforcing layer are arranged so as to be inclined with respect to the tire circumferential direction. While extending in the tire width direction beyond both ends of the layer, the inclination angle θ of the fiber cord of the belt reinforcing layer is set to 15 ° ± 5 °, while the inclination direction is the same as that of the steel cord of the belt layer adjacent inside. And the ratio of the width A of the belt reinforcing layer to the width B of the belt layer is set to 1.12 to 1.18, the following excellent effects are obtained.

That is, since the fiber cords of the belt reinforcing layer are arranged to be inclined with respect to the tire circumferential direction, when the green tire is inflated, the belt reinforcement is more enhanced than when the fiber cords are arranged in the tire circumferential direction as before. Since the displacement of the layers can be reduced, the deformation of the belt layer and the cap tread layer together with the displacement can be suppressed, the uniformity can be improved, and as a result, the riding comfort is improved. be able to.

Further, the belt reinforcing layer is extended in the tire width direction beyond both ends of the belt layer, and the inclination angle of the fiber cord of the belt reinforcing layer and the ratio of the width of the belt reinforcing layer to the width of the belt layer are set in the above range. Since the fiber cord of the belt reinforcing layer disposed outside the belt layer is set to have the same inclination direction as the steel cord of the belt layer adjacent to the inside thereof, it acts between the belt layer and the belt reinforcing layer. Shear force can be reduced, and the occurrence of edge separation during that can be suppressed,
Not only does high-speed durability not be impaired, but also higher-speed durability can be ensured as compared with a conventional arrangement in which a belt reinforcing layer in which fiber cords are arranged along the tire circumferential direction is arranged.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view of an example of a pneumatic tire according to the present invention in the meridian direction, FIG. 2 is an explanatory plan view of an essential part of the pneumatic tire, and FIGS. FIG. 4 (A) is an explanatory view showing an arrangement relationship with the conventional tire, and FIG.
FIG. 4 (B) is an explanatory view showing RFV of the tire of the present invention, and FIGS. 5 (A) and 5 (B) are explanatory views showing splicing conditions of a conventional belt reinforcing layer. DESCRIPTION OF SYMBOLS 1 ... Splice part, 2 ... bead wire, 3 ... Carcass layer, 4 ... Tread part, 5 ... Belt layer, 5u ... Upper belt layer, 5d ... Lower belt layer, 6 ... Belt reinforcement layer , 6a ... code.

Claims (1)

(57) [Claims] 1. A pneumatic tire in which a belt layer in which steel cords are arranged obliquely with respect to the tire circumferential direction and a belt reinforcing layer in which fiber cords are arranged are stacked and arranged outside the carcass layer of the tread portion. The belt reinforcing layer is disposed outside the belt layer, and the fiber cords of the belt reinforcing layer are arranged so as to be inclined with respect to the circumferential direction of the tire. While the inclination angle θ of the fiber cord of the belt reinforcing layer is set to 15 ° ± 5 °, the inclination direction is the same as that of the steel cord of the belt layer adjacent inside, and the belt reinforcing layer has A pneumatic tire, wherein a ratio of a width A to a width B of the belt layer is set to 1.12 to 1.18.