JP3205396B2 - Pneumatic tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, especially a heavy duty pneumatic tire having a low flatness, used for trucks, buses, and the like, and relates to an improvement in a belt structure thereof.

[0002]

2. Description of the Related Art A belt structure of a pneumatic tire of this type has a cord layer in which cords are arranged at an angle of 15 to 25 degrees with respect to the equatorial plane of the tire, and the cord layers intersect each other across the equator. At least two layers, that is, a so-called cross belt layer are used as main reinforcing means.

[0003] This cross belt layer maintains the toroidal shape of the carcass, and has a crouching action for ensuring a relatively flat tread surface and appropriately resists the lateral force generated when the tire corners. For securing the shear stiffness for the purpose.

By the way, not only passenger car tires, but also truck and bus tires tend to decrease the flattening rate. With this flattening, the above-mentioned belts strengthen the crouching action, that is, It is necessary to increase the circumferential rigidity. However, the conventional belt structure is
Since the cords of the adjacent cord layers are inclined with respect to the equatorial plane of the tire, it is not possible to give the flat tire a necessary and sufficient crouching force.

[0005]

On the other hand, according to the belt layer, a high-rigidity steel cord or the like is used and this cord is arranged along the equator of the tire. be able to. However, when the steel cord is arranged along the equator of the tire, the diameter of the tire cannot be changed from molding to vulcanization, especially during tire production, making the production difficult, and the belt on the carcass surface becomes difficult. The desired effect cannot be obtained due to the ripples and the joints being exposed.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic tire having a belt structure improved so as to advantageously satisfy the performance required of the belt.

[0007]

SUMMARY OF THE INVENTION The present invention obtains two performances required for a belt structure of a pneumatic tire, namely, a circumferential rigidity for maintaining a toroidal shape of a carcass and a resistance to a lateral force. Out of shear stiffness
By arranging a reinforcing member that particularly bears the circumferential rigidity, which tends to be insufficient, both rigidities are increased.

That is, the present invention relates to a belt comprising a carcass straddling in a toroidal manner between a pair of bead cores and a rubberized layer of a reinforcing element comprising a plurality of cords or filaments surrounding a crown portion of the carcass. The belt comprises at least two rubberized layers in which reinforcing elements arranged in parallel with each other are arranged at an angle to the equatorial plane of the tire, and the belts are arranged so that the reinforcing elements intersect with each other. Crossed belt layer, laminated
At least one corrugated belt layer using reinforcing elements arranged in a waved pattern in the same rubberized layer and oriented along the equator of the tire, and a parallel arrangement with each other arranged at an angle to the equatorial plane of the tire. At least one protective belt layer using a reinforcing element to be formed is sequentially laminated outward in the tire radial direction of the carcass, and the width of the corrugated belt layer is the maximum width of the cross belt layer and the maximum width of the protective belt layer. It is a pneumatic tire characterized by being narrower than that.

Here, the waveform applied to the reinforcing element of the corrugated belt layer may be a zigzag shape that bends and changes in addition to a shape that changes sinusoidally.

FIG. 1 illustrates a specific example of a tire 1 according to the present invention.
Is a protective belt layer, 5 is a carcass, and 6 is a bead core. The cross belt layer 2, the corrugated belt layer 3, and the protective belt layer 4 form a laminated structure shown in FIG.
It functions as a belt that contributes to the strengthening of the crown. In the figure, reference numeral 7 denotes a reinforcing element made of cords or filaments of the cross belt layer 2 having two layers in this example and the protective belt layer 4 having one layer in this example. It is not necessarily required, and the inclination angle of the cross belt layer is preferably 15 to 30 °, and the inclination angle of the protection belt layer is 10 ° to 50 ° with respect to the equatorial plane of the tire 1. Reference numeral 8 denotes a reinforcing element arranged in a corrugated manner in the corrugated belt layer 3 having two layers in this example and oriented in a direction along the equator of the tire 1.

The laminated structure of the belt is such that a cross belt layer 2, a corrugated belt layer 3, and a protective belt layer 4 are sequentially disposed outside the carcass 5 in the tire radial direction, and the width of the corrugated belt layer 3 is reduced.
It is important that the width is smaller than the maximum width of the cross belt layer 2 and the maximum width of the protection belt layer 4.

[0012]

By using a reinforcing element oriented in the direction along the equator of the tire, the corrugated belt layer can give a strong crouching action, making it possible to flatten the tire. Here, since the reinforcing element of the corrugated belt layer is corrugated, it hardly hinders the expansion of the belt diameter at the time of tire production, so that the tire can be easily produced by the molding and vulcanizing technique according to the conventional practice.

Further, since there is no cord end at the belt end portion in the radial cross section of the tire as in the conventional cross belt, even if circumferential tension is applied to the belt, shear strain is not generated at the belt end portion. Separation is avoided because it does not occur.

On the other hand, the crossed belt layer plays a role as a means for securing the shear rigidity of the tire. Therefore, it is necessary to form the reinforcing element from at least two layers that are stacked in an intersecting arrangement. In particular, in the case of tires for large trucks and buses, since the lateral force generated by heavy load is large, it is necessary to use at least two layers because the shear rigidity is insufficient if the cross belt layer is a single layer. No.

Here, in the above-mentioned laminated structure of the cross belt layer, the corrugated belt layer and the protective belt layer, it is necessary to regulate the lamination order and the width of each belt layer. That is, when the corrugated belt layer is disposed between the carcass and the cross belt layer, the cord (or filament) constituting the carcass is caused by the displacement (wave amplitude change) of the corrugated reinforcing element in the belt width direction. An input along the longitudinal direction is generated, fretting fatigue is given to the cord, and the cord is broken. Therefore, it is necessary to arrange the corrugated belt layer outside the cross belt layer in the tire radial direction.

However, if the corrugated belt layer is simply disposed outside the cross belt layer in the tire radial direction, a large shear strain is generated between the tread and the tread due to the displacement of the corrugated reinforcing element in the belt width direction. Separation occurs with the corrugated belt layer. Therefore, the corrugated belt layer is arranged on the outer side in the tire radial direction of the crossed belt layer, and a protective belt layer is arranged between the crossed belt layer and the tread to divide the two, and each movement of the corrugated belt layer and the tread is controlled. Cut off.

The width end of the corrugated belt layer is formed of a cross belt layer and a protective belt layer in order to avoid the adverse effect of the corrugated reinforcing element due to the displacement of the reinforcing element in the belt width direction, that is, to cut off the corrugated belt from the tread and the carcass. In other words, it is necessary that the width of the corrugated belt layer be smaller than the maximum width of the cross belt layer and the maximum width of the protection belt layer.

[0018]

EXAMPLE A tire having a tire size of 11/70 R 22.5 was prototyped in accordance with the structure shown in FIGS. 1 and 3, and the results of evaluating the carcass residual strength and durability are shown in Table 1 in comparison. The belt structure of each test tire is as shown in Table 1.

The remaining strength of the carcass is determined by an internal pressure of 8.0 kgf / c.
After running a tire with m ² and a load of 2725 kg for 50,000 km,
The cord of the carcass ply was subjected to a tensile test, the stress at break was measured, and the result was expressed as an index with the stress of the new tire as 100. In the durability test, the tire is run under the accelerated drum test conditions (internal pressure: 8.0 kgf / cm ² , load 4000 kg), and the inflated portion generated by the separation on the belt is detected by a sensor, and the occurrence of the inflated portion is detected. At the same time, the running was stopped, and the running distance at that time was measured. Although the example shown in the embodiment has two corrugated belts, one corrugated belt may be used depending on the tire size.

[0020]

[Table 1]

[0021]

According to the present invention, the belt performance required for a pneumatic tire can be advantageously achieved, and in particular, the flattening effect of the belt can be enhanced because the belt crouching action is enhanced. Can be.

[Brief description of the drawings]

FIG. 1 is a sectional view of a tire according to the present invention.

FIG. 2 is a schematic diagram showing a layering procedure of a belt.

FIG. 3 is a sectional view of a tire.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tire 2 Cross belt layer 3 Corrugated belt layer 4 Protective belt layer 5 Carcass 6 Bead core

Claims (1)

(57) [Claims] 1. An air comprising a carcass straddling in a toroidal manner between a pair of bead cores, and a belt comprising a rubberized layer of a reinforcing element comprising a plurality of cords or filaments surrounding a crown portion of the carcass. A tire, wherein the belt has at least two rubberized layers in which reinforcing elements arranged in parallel to each other are arranged at an angle to the equatorial plane of the tire, and the reinforcing elements are laminated in an arrangement in which the reinforcing elements cross each other. A crossed belt layer, at least one corrugated belt layer using reinforcing elements arranged in a corrugated manner in the same rubberized layer and arranged along the equator of the tire, and arranged at an angle to the equatorial plane of the tire, At least one protective belt layer using reinforcing elements arranged in parallel to each other is sequentially laminated outward in the tire radial direction of the carcass. A pneumatic tire, wherein the width of the layer is narrower than the maximum width of the cross belt layer and the maximum width of the protection belt layer.