JP4513232B2 - Pneumatic radial tire - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic radial tire, and more particularly, to a pneumatic radial tire that improves the wavy phenomenon of a belt layer.
[0002]
[Prior art]
The groove on the tread surface is formed by grooving the unvulcanized tire in the mold while the groove forming protrusion on the inner surface of the mold bites into the tread surface and pushes away the rubber on the tread portion. In particular, in the case of a circumferential groove having a groove width wider than that of other grooves and a deep groove depth, the amount of biting of the groove forming protrusion is large. Therefore, the circumferential groove inner circumferential side portion of the belt layer embedded in the tread portion is partially pushed down to the inner circumferential side by the groove forming projection, and a wave phenomenon occurs in the belt layer.
[0003]
Such waviness of the belt layer adversely affects high-speed durability and uneven wear resistance of the tire. Since a large force is applied to both shoulders of the tread when turning left and right, the circumferential groove located on the outer side increases uneven wear around it, and from the belt layer portion on the outermost circumferential groove inner circumference side Destruction is likely to occur.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a pneumatic radial tire that can reduce the amount of corrugation of a belt layer and improve high-speed durability and uneven wear resistance.
[0005]
[Means for Solving the Problems]
The present invention to achieve the above object, embedded a plurality of belt layers on the carcass layer outer peripheral side of the tread portion, the pneumatic radial tire provided with a plurality of circumferential grooves in the tread surface, among the plurality of circumferential grooves A reinforcing layer is arranged on the circumferential side and on the inner circumferential side of the outermost belt layer, and the reinforcing layer is formed of a reinforcing cord spirally wound in the tire circumferential direction, and the reinforcing cord is disposed between the circumferential grooves. The reinforcing layer is wound in a sparser state than the winding density of the reinforcing layer, and adjacent reinforcing layers are continuously formed of the same reinforcing cord .
[0006]
Corresponding to a plurality of circumferential grooves, the reinforcing layer is arranged on the inner circumferential side from the outermost belt layer as described above to increase the rigidity on the inner circumferential side of the circumferential groove. Even if the molding protrusions bite into the tread surface greatly, the belt layer is not greatly pushed down. Such an effect is effective when the reinforcing layer is disposed on the inner side of the outermost peripheral belt layer, and a sufficient effect cannot be obtained if it is disposed on the outer side of the outermost peripheral belt layer. Therefore, the waviness of the belt layer can be suppressed, and high-speed durability and uneven wear resistance can be improved.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
[0008]
FIG. 1 shows an essential part of the pneumatic radial tire of the present invention, where 1 is a tread portion, 2 is a carcass layer, and 3 is a belt layer. The carcass layer 2 is mounted between left and right bead portions (not shown), and both end portions thereof are folded around the bead core from the tire inner side to the outer side. A plurality (two layers in the figure) of belt layers 3 are embedded on the outer peripheral side of the carcass layer 2 of the tread portion 1. The tread surface 1A is provided with a plurality of circumferential grooves 4 that extend straight or zigzag in the tire circumferential direction.
[0009]
On the inner peripheral side of each circumferential groove 4, a rubber-coated reinforcing cord x is spirally formed in the tire circumferential direction between the innermost first belt layer (innermost peripheral belt layer) 3 </ b> A and the carcass layer 2. A reinforcing layer 5 wound continuously is provided.
[0010]
As the reinforcing cord x of the reinforcing layer 5, an organic fiber cord such as a nylon cord or an aramid cord, or a metal cord such as a steel cord can be used.
[0011]
In this way, the reinforcing layer 5 is disposed on the inner peripheral side of the outermost second belt layer 3B so as to be sandwiched between other layers, and the inner peripheral side of the circumferential groove 4 is reinforced, thereby performing vulcanization molding. In addition, it is possible to effectively suppress the belt layer 3 from being pushed down when the circumferential groove-forming projections on the inner surface of the mold are greatly sunk into the tread surface 1A, and the undulation amount of the belt layer 3 can be greatly reduced. Therefore, high-speed durability and uneven wear resistance can be improved.
[0012]
In particular, by sandwiching the reinforcing layer 5 between the belt layer 3 and the carcass layer 2, as possible out to further enhance the effect described above.
[0013]
In addition, a plurality of reinforcing layers 5 are formed with the same reinforcing cord x, and the reinforcing cord x is wound between the circumferential grooves 4 so as to be sparser than the winding density of the reinforcing layer 5, and the adjacent reinforcing layers 5 are the same. the Rukoto forming continuously form the reinforcement cords x, in addition to the effects mentioned above, it is possible to improve the productivity in forming a plurality of reinforcing layers 5.
[0014]
In the present invention, when an organic fiber cord is used as the reinforcing cord x of the reinforcing layer 5, the winding angle with respect to the tire circumferential direction is preferably 15 degrees or less and more than 0 degrees. When the reinforcing cord x of the reinforcing layer 5 is formed of a metal cord, the winding angle with respect to the tire circumferential direction is preferably 15 degrees or less and more than 5 degrees. If the winding angle exceeds the above angle, the winding density of the reinforcing cord x becomes too sparse and the effect of suppressing the undulation of the belt layer 3 becomes insufficient, so that high-speed durability and uneven wear resistance are effectively improved. I can't.
[0015]
The width A of the reinforcing layer 5 is preferably 1.2 times to 4.0 times the groove width B of the circumferential groove 4. If the width A of the reinforcing layer 5 is smaller than 1.2 times the groove width B, the effect of suppressing the undulation of the belt layer 3 is insufficient, so that it is difficult to effectively improve the high-speed durability and uneven wear resistance. . Conversely, even if it is larger than 4.0 times, the improvement effect does not change.
[0016]
In the present invention, the groove width B of the circumferential groove refers to the opening width in the tread width direction on the tread surface. When the circumferential groove 4 is formed in a zigzag shape, the runout width is referred to as the groove width B. To do.
[0017]
In particular, the present invention can be suitably used for a pneumatic radial tire including a circumferential groove 4 having a groove width B of 6 mm or more and a groove depth of 8 mm or more that greatly affects the undulation of the belt layer 3.
[0018]
【The invention's effect】
As described above, the present invention provides a pneumatic radial tire in which a plurality of belt layers are embedded on the outer circumferential side of the carcass layer of the tread portion, and a plurality of circumferential grooves are provided on the tread surface, and the inner circumferential side of the plurality of circumferential grooves. In addition, the reinforcing layer is disposed on the inner peripheral side of the outermost peripheral belt layer, and the reinforcing layer is formed of a reinforcing cord spirally wound in the tire circumferential direction, and the reinforcing cord is interposed between the circumferential grooves. Winding with a density less than the winding density, and adjacent reinforcing layers were continuously formed with the same reinforcing cord , reducing the wavy amount of the belt layer and improving high-speed durability and uneven wear resistance it can.
[Brief description of the drawings]
FIG. 1 is a tire meridian cross-sectional view showing a main part of a pneumatic radial tire of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Tread part 1A Tread surface 2 Carcass layer 3 Belt layer 3A 1st belt layer 3B 2nd belt layer (outermost belt layer)
4 Circumferential groove 5 Reinforcement layer
A Reinforcement layer width B Groove width x Reinforcement cord

Claims (6)

In a pneumatic radial tire in which a plurality of belt layers are embedded on the outer circumferential side of the carcass layer of the tread and a plurality of circumferential grooves are provided on the tread surface, the inner circumferential side of the plurality of circumferential grooves and the outermost belt layer A reinforcing layer is disposed on the inner peripheral side, and the reinforcing layer is formed of a reinforcing cord spirally wound in the tire circumferential direction. The reinforcing cord is less dense than the winding density of the reinforcing layer between the circumferential grooves. A pneumatic radial tire which is wound in such a state that adjacent reinforcing layers are continuously formed of the same reinforcing cord .   The pneumatic radial tire according to claim 1, wherein the reinforcing layer is disposed between the innermost peripheral belt layer and the carcass layer.   The pneumatic radial tire according to claim 1 or 2, wherein a width of the reinforcing layer is 1.2 times to 4.0 times a groove width of the circumferential groove.   The pneumatic radial tire according to claim 1, 2, or 3, wherein the reinforcing layer has an organic fiber cord wound in a tire circumferential direction, and a winding angle of the organic fiber cord with respect to the tire circumferential direction is set to 15 degrees or less.   The pneumatic radial tire according to claim 1, 2, 3, or 4, wherein the circumferential groove has a groove width of 6 mm or more and a groove depth of 8 mm or more.   The pneumatic radial tire according to claim 1, 2, 3, 4, or 5, wherein a belt reinforcing layer is disposed on an outer peripheral side of the outermost peripheral belt layer.