JPH01282004A - Pneumatic tyre - Google Patents

Abstract

PURPOSE:To prevent the degradation of uniformity due to splicing by splitting the central part of the tyre crown of a belt layer, providing a specific reinforcing layer on this part part and dispersing the spliced part of the reinforcing layer around the tyre periphery. CONSTITUTION:Among a plural number of belt layers 51-53, for example, the first belt strengthening layer 51 counted from the carcass direction of a tyre toward the tread direction is formed in a split structure and in the central part of its crown, a reinforcing layer 5c made of organic fiber cord is provided. The reinforcing layer 5CL is set in the same width as that of the first belt strengthening layer 51 split in its width, formed with a plural number of layers 5a and 5b divided in the width direction and at the same time, those layers are wound around while they are mutually shifted in the tyre peripheral direction so that the spliced part S of each of the layers 5a and 5b may be dispersed on the tyre periphery. Also the organic fiber cord is positioned at a cord angle of almost 0 deg. against the tyre peripheral direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a pneumatic tire in which deterioration in uniformity and uniformity of the tire due to splice portions of a belt reinforcing layer is prevented.

[Conventional technology]

In recent years, the performance required of tires has widened.
Accordingly, various types of tire belt structures have been adopted.

For example, for radial tires for passenger cars, Figure 4A
As shown in the figure, a belt tension layer 5 made of cords inclined in the tire circumferential direction E-E' is arranged on the carcass layer side between the carcass layer 4 and the tread 3, and a belt tension layer 5 made of cords inclined in the tire circumferential direction E-E' is arranged on the tread 3 side and mutually with the belt tension layer 5. A belt structure in which a heald tension layer 5° having an intersecting cord arrangement is arranged with its both ends bent inward, and a belt tension belt having a mutually intersecting cord arrangement with one end bent inward as shown in Fig. 4B. 1!5
．． Furthermore, as shown in FIG. A belt structure wrapped in a reinforcing layer has been proposed.

Adopting this structure prevents the shoulder of the heald layer from rising when driving at high speeds, and by providing a separation section in the belt layer at the center of the tire, the rigidity of the center is reduced, improving steering stability. is ensured. and,
In a tire with this type of structure, a reinforcing layer 6 made of organic fiber cord is arranged at an angle of approximately 0° with respect to the tire circumferential direction in order to maintain a certain degree of rigidity in the tire circumferential direction in the spaced apart part of the heald layer. It is common to do so.

In addition, in the case of a heavy-duty tire that is used under particularly severe running conditions, as shown in FIG. There is a radial tire with a so-called sprint structure in which the belt layers are separated at the center of the tire crown, the belt layer is divided into two parts on both shoulders, and belt tension layers 5□ and 53 are further arranged on the outside thereof.

The reinforcing layer 6 of the former radial tire has the function of increasing the rigidity in the tire circumferential direction in combination with the belt layer 5.5 degrees. In addition, in the latter radial tire, in order to suppress the deterioration of the belt reinforcement effect caused by the split structure and improve the separation length at the end of the belt layer, an organic material with a cord angle of 06 to 106 is placed in the center of the crown. A structure in which a reinforcing layer 5CL made of fiber cord is arranged has been proposed (for example, Japanese Patent Laid-Open No. 63-22702).

For example, when manufacturing the radial tire shown in FIG. 5, belt reinforcing layers 5. A reinforcing layer 5 having a width approximately corresponding to the distance between the carcass layer 4 and the belt tension layer 5 □ at the center of the crown of the belt.
It is normal to wind the CL and overlap its terminal parts,
This end chamber portion forms a splice S as shown in FIG. Further, on the reinforcing layer 5CL having such a splice portion S, another belt tension layer 5□, 5
It is common to prepare a green tire by arranging tire constituent members such as 3 and a tread portion, and heat and pressurize this green tire in a vulcanization mold to produce a product tire.

In such a radial tire manufacturing process, the green tire before vulcanization is molded with a smaller outer circumference than the vulcanization mold, and the tire is grown by applying pressure from the inside of the green tire in the vulcanization mold. The outer circumference is brought into close contact with the inner circumferential surface of the vulcanization mold (called a lift).
, molded and vulcanized. However, when this lift is applied, the belt reinforcement layer 5. and belt tension layer 5□, 53
The outer circumferential length of the reinforcing layer 5cL, which is arranged at an angle of approximately 0° with respect to the tire circumferential direction, can grow due to the arrangement structure of its constituent cords, whereas the reinforcing layer 5cL, which is arranged at an angle of approximately 0° with respect to the tire circumferential direction, either stretches itself or grows at the splice portion. Unless the overlapping cord terminals in S are shifted from each other, they cannot grow. Actually, compared to the tensile strength of the cord, the splice S
Since the adhesion of the splice is small, the growth during tire molding is due to the misalignment of the splice. As a result, the belt layer and tread also grow in the area adjacent to the splice, and the uneven portions of the tire, which cause vehicle vibration during high-speed running and reduced high-speed durability, are caused by the splice (= This phenomenon will particularly increase the disorder of the cords in the belt reinforcing layer 5, and when a durability test is carried out with the tire mounted on a vehicle, the splice This is also supported by the fact that there is abnormal wear around the splice part, and that peeling failures occur mostly from the splice part during indoor high-speed durability tests.

The above-mentioned phenomenon is also observed in the bell I structure of the passenger car tire shown in FIGS. 4A, B, and C.

[Purpose of the invention]

The purpose of the present invention is to prevent the deterioration of tire uniformity and uniformity caused by the splice portion of the reinforcing layer, especially the influence of lift during tire molding and vulcanization, and to further improve ride comfort such as durability and comfort. An object of the present invention is to provide a pneumatic tire with improved performance.

[Structure of the invention]

In the pneumatic tire of the present invention, in a tire in which a plurality of belt layers are arranged between a tread and a carcass layer, the center portion of the tire crown of at least one belt layer among the belt layers is spaced apart, and this separation A reinforcing layer consisting of organic fiber cords arranged at a cord angle of approximately 0@ with respect to the circumferential direction of the tire, having a width approximately corresponding to the spaced interval, and divided into at least two or more parts in the width supplementary area, in the center of the crown. are arranged, and the splice portions of these reinforcing layers are arranged so as to be distributed over the circumference of the tire.

Hereinafter, the tire of the present invention will be explained in detail based on the embodiment of the heavy-duty tire shown in FIG. 5. However, in the case of the passenger car tire shown in FIG. They are substantially the same except that 51 is omitted.

As shown in FIG. 1, in the present invention, among the plurality of belt layers, the first belt reinforcing layer 5° counted in the 1-let direction from the carcass layer of the tire has a split structure,
A reinforcing layer 5 made of organic fiber cord is placed in the center of the crown.
Provide CL (carcass layer 4 and second belt layer 5)
2) and the width of this reinforcing layer 5CL is the same as the space between the splinted first belt reinforcing layers 5I, and the width of the reinforcing layer 5CL is at least 2 in the width direction. The layers are divided into the above, and each reinforcing layer is 5 cL.
It is characterized in that the splice portions S of the tires are wound so as to be shifted from each other in the circumferential direction of the tire so that they are distributed over the same area of the tire.

FIGS. 2A and 2B show the reinforcing layers 5m and 5.0m divided in the width direction in the present invention. This is a schematic plan view of a 5 m splice part, in which the reinforcing layer 5. is attached to the splice S of the reinforcing layer 58. splice S2 (not shown) is not present, reinforcing layer 5. The splices s2 are arranged at substantially symmetrical positions (opposite sides) on the outer circumference of the tire. The splice portion may be formed by cutting the ends of the reinforcing layer diagonally and stacking them as shown in Figure 2A, or by cutting them parallel to each other and stacking them as shown in Figure 2B. Can be shaped.

In the present invention, the splice portion of the reinforcing layer, which is divided into at least two parts in the width direction, is distributed and arranged on the outer circumference of the tire. adjacent to the splice,
The non-splice part (the part where the ends of the reinforcing layer do not overlap) is distributed, and the parts where the splice part and the non-splice part are arranged in parallel are distributed on the outer circumference of the tire. In combination, the splice portion of the reinforcing layer prevents or suppresses abnormal deformation of the belt layer.

In the present invention, it is important that the reinforcing layer is provided at the split portion of the first belt reinforcing layer counting from the carcass layer in the tread direction. This is to prevent the above-mentioned lift during molding and vulcanization of the tire from being directly transmitted to the belt tension layer, and to absorb this lift by the reinforcing layer of the present invention and mold the tire uniformly. This makes it possible to manufacture tires with excellent uniformity.

In the embodiment shown in FIG. 5, the belt 1 tension layer has two layers, but it goes without saying that the present invention also covers cases where the belt tension layer has three or more layers.

The width of the entire reinforcing layer of the present invention needs to approximately correspond to the distance that the first belt reinforcing layer is separated (split). This is undesirable because the split portion will have an asymmetrical structure, making tire performance unstable.Also, depending on the number of parts into which the reinforcing layer is divided in the width direction, the widths of the multiple reinforcing layers should be approximately the same. It is desirable that the number of divisions in the width direction of the reinforcing layer is 2, since as the number increases, the number of splices increases and the productivity of the tire also decreases.
~3 pieces, preferably 2 pieces. The reinforcing layer may be one piece divided along its length, or may be made separately.

In addition, the angle of the cord constituting the reinforcing layer is preferably Oo with respect to the tire circumferential direction from the viewpoint of tire durability as described above, but it does not have to be strictly Oo.
It is sufficient if the cord angle is .

The organic fiber cords constituting the reinforcing layer of the present invention include nylon 6, nylon 66, polyester fibers, aromatic polyamide fibers, etc., but are not particularly limited.゛Hereinafter, the effects of the present invention will be specifically explained using Examples and Comparative Examples.

The tire uniformity is JASOC607.
Evaluation was made by radial runout (RRO) and radial force variation (IIFV), which measure tire irregularities around the tire circumference, in accordance with the ``Uniformity Test Method for Automotive Tires''.

Examples and Comparative Examples A reinforcing layer consisting of two nylon coats with a width of 300 ffl111 was created, and these two reinforcing layers were placed at the center of the first heald reinforcing layer 5I having a split structure (with an interval of 6
00 mm), at a spaced apart position of the belt reinforcing layer 51,
As shown in Figure 2A, the splice parts of the reinforcing layer divided into two in the width direction are arranged in parallel so that they are located at approximately opposite positions on the outer circumference of the tire, and the tire size is 100O.
An R2014PR tire (tire of the present invention) was created.

On the other hand, a reinforcing layer made of one piece of the above-mentioned nylon cord having a width of 600 mm was created, and this reinforcing layer was similarly applied to the central part of the first belt reinforcing layer 51 having the splint structure (with an interval of 600 mm>). , located at a distance from the belt reinforcing layer 51, and the tire size is 1000R2014PR.
Comparative tires were prepared (the circumferential length of each splice portion during tire molding was 50 mm).

Regarding these two types of tires, the RI? O and IIFV were measured. The results are shown in the table.

Further, Char 1 of the RRO measurement is shown in FIG.

(Hereinafter, blank spaces) As mentioned above, the above explanation is based on the example of the heavy-duty tire shown in Fig. 5, but
The same applies to the passenger car tire shown in FIG. 4, where the reinforcing layer 6 of the passenger car tire shown in FIG. By doing so, it is possible to prevent the cords of the belt layers located on both sides of the separated position in the width direction from being disturbed, and it is possible to obtain a tire that is uniform and has excellent durability.

〔Effect of the invention〕

According to the present invention, at least one of the plurality of belt layers is separated at the center of the crown, and organic fibers are arranged at the center of the separated crown at a cord angle of approximately 0° with respect to the tire circumferential direction. By arranging a reinforcing layer made of a cord, having a width approximately corresponding to the above-mentioned distance, and divided into at least two parts in the width direction, and distributing the splice portions of these reinforcing layers over the circumference of the tire, the splice can be formed. It is possible to prevent the deterioration of uniformity and uniformity during tire molding caused by this, and to obtain a tire with less vibration during running and excellent comfort and durability.

[Brief explanation of the drawing]

FIG. 1 is a developed plan view showing the laminated state of the belt layer and reinforcing layer of the tire of the present invention, FIGS. 2A and B are partial plan views of the reinforcing layer of the tire of the present invention developed, and FIG. 3 is a conventional tire. 4A, B, and C are partial cross-sectional views of the tread portion showing an embodiment of the passenger car tire of the present invention, and FIG. 5 shows that the first heald layer has a splint structure. FIG. 6 is a partial cross-sectional view of a main part of a tread portion showing an embodiment of a heavy-duty tire of the present invention having a tire uniformity, and is a chart of RRO measurement without showing tire uniformity. 4... carcass layer, 5. ...belt reinforcement layer, 5CL
... Reinforcement layer, 5. ．． 5b...Divided reinforcement layer, S.
・Splice part. Agent Patent Attorney Nobuo Ogawa −

Claims (4)

[Claims] (1) In a tire in which a plurality of belt layers are arranged between a tread and a carcass layer, the center portion of the tire crown of at least one belt layer among the belt layers is separated, and the center portion of the crown of the tire is separated from the center portion of the crown. , consisting of organic fiber cords arranged at a cord angle of approximately 0° with respect to the circumferential direction of the tire, having a width approximately corresponding to the spaced interval, and having a reinforcing layer divided into at least two parts in the width direction, and A pneumatic tire characterized in that the splice portions of these reinforcing layers are arranged so as to be distributed over the circumference of the tire. (2) The pneumatic tire according to claim 1, wherein the spaced apart belt layers are formed of a single ply with both ends bent inward, and the tire is for a passenger car. (3) The pneumatic tire according to claim 1, wherein the pneumatic tire is for a passenger car, and the belt layer is formed by combining two plies with one end bent inward. (4) The pneumatic tire according to claim 1, wherein the spaced apart belt layer is a belt reinforcement layer adjacent to the carcass layer, and the tire is for heavy loads.