JPH04355121A - Ribbonlike reinforcing layer and pneumatic radial tire for which same is used - Google Patents

Abstract

PURPOSE:To improve high-speed durability by preventing generation of an air rich area in overlapped wound-round part of a ribbonlike reinforcing layer. CONSTITUTION:The title radial tire is comprised by coating a plurality of reinforcing cords 1 with rubber and count density of the reinforcing cords 1 in at least one side end part is made lower than that of the central part.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] This invention relates to a ribbon-shaped reinforcing layer wound around the outer circumference of a belt layer, and a pneumatic radial tire using the same, for the purpose of improving high-speed durability of the tire. .

0002

[Prior Art] Conventional tires of this type include organic fiber cords in at least one side region of the belt layer, adjacent to the radial outer circumferential side of the belt layer, which is made of steel cords; The auxiliary layer is constructed by spirally winding a ribbon-shaped reinforcing layer having a width of, for example, 5 to 50 mm, which is formed by rubber-coating and molding a plurality of reinforcing cords, for example, 2 to 20 reinforcing cords extending substantially parallel to the However, there are some tires in which the degree of reinforcement of this auxiliary layer is adjusted by selecting the amount of overlap of the ribbon-shaped reinforcing layer. It is possible to effectively restrain bulging deformation and advantageously avoid belt layer peeling.

0003

However, in this prior art, the ribbon-like reinforcing layer wound in an overlapping manner in at least one side region of the belt layer has a rectangular cross section in the width direction. As shown in FIG. 3, the ribbon-shaped reinforcing layer is placed adjacent to the outer circumferential side of the belt layer, as shown in FIG. When the coating rubber is wound in such an overlapped state, free deformation of the coating rubber is prevented by the reinforcing cord a. Air pockets d and e whose cross-sectional shapes are approximately triangular are generated, and these air pockets d and e
However, particularly in ultra-high-performance tires, there is a problem in that the auxiliary layer f made of the wound ribbon-shaped reinforcing layer and the tread rubber c peel off, significantly impairing high-speed durability.

The present invention advantageously solves the problem of the prior art, and when the ribbon-shaped reinforcing layer is wound in an overlapping manner, the gap between the auxiliary layer and each layer adjacent thereto is The present invention provides a ribbon-shaped reinforcing layer that can sufficiently prevent the formation of air pockets and greatly improve the high-speed durability of the tire, and a pneumatic radial tire using the same.

[0005]

[Means for Solving the Problems] The ribbon-shaped reinforcing layer of the present invention has, for example, a plurality of reinforcing cords extending parallel to each other coated with rubber, and the reinforcing cord implantation density at at least one side end portion is increased. , is smaller than that of the central portion, and more preferably, at least one side edge portion is formed only of rubber, and the thickness is gradually made thinner toward the side edge.

The pneumatic radial tire of the present invention also has a belt layer on the radially outer peripheral side of at least two belt layers each consisting of cords extending at a relatively small angle with respect to the tire equatorial plane and intersecting each other. , the auxiliary layer was constructed by winding the aforementioned ribbon-like reinforcing layer in the side area of at least one of both belt layers with a desired overlap amount, such as 1/2, 2/3 of itself. More preferably, the auxiliary layer is composed of a ribbon-shaped reinforcing layer that covers the entire width direction of at least two belt layers by spiral winding, and the winding pitch of the ribbon-shaped reinforcing layer is set such that the winding pitch of the ribbon-shaped reinforcing layer is , larger in the central area of the belt layer and smaller in the side areas.

[0007]

[Function] In the ribbon-shaped reinforcing layer of the present invention, the driving density of the reinforcing cords is set at at least one side end portion in the width direction, for example, the side end portion in contact with the belt layer, than that of the central portion. By reducing the size, the fluidity of the coating rubber in an unvulcanized state can be greatly improved compared to the conventional technology. With its excellent fluidity, it can be brought into close contact with each of the upper and lower surface members, and as a result, it is possible to effectively prevent the formation of air pockets in the overlapped winding portion. This is even more noticeable when at least one side end portion of the ribbon-shaped reinforcing layer is made of rubber only, and the side end portion is made gradually thinner toward the side edge.

[0008] Accordingly, such a ribbon-like reinforcing layer can be applied to at least two belt layers, also in at least the lateral regions.
In a pneumatic radial tire that is wound with its own overlap, air pockets can be prevented from forming in the overlap area, and the risk of peeling of the auxiliary layer and tread rubber can be sufficiently eliminated. The high-speed durability of can be greatly improved.

By the way, when such a pneumatic radial tire is provided with an auxiliary layer formed by winding a ribbon-shaped reinforcing layer over the entire width of the belt layer, the ribbon-shaped reinforcing layer is also formed in the central area of the belt layer. Because of the presence of the ribbon, the central area is prevented from rising, and the end portions of the ribbon-shaped reinforcing layer are easily deformed by the rubber, so that they can be adjoined smoothly and air pockets can be prevented. Moreover, since there is relatively little rise in the central region, weight reduction can be considered by increasing the winding pitch of the ribbon-shaped reinforcing layer.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view in the width direction illustrating the ribbon-shaped reinforcing layer of the present invention. In the example shown in Fig. 1(a), five linear reinforcing cords 1, such as nylon cords, extending parallel to each other are coated with rubber 2, and the cross-sectional shape is also a rectangle with a width of 10 mm, for example. , three of the five reinforcing cords 1 are placed in the center part 3 in the width direction, and each side end part 4 is
By arranging one reinforcing cord 1 at each side, the reinforcing cord implantation density at both end portions 4 of the ribbon-shaped reinforcing layer 5 is made smaller than that at the central portion 3. Note that the width of such a ribbon-shaped reinforcing layer is 5
~15mm, and the thickness is 0.7~1.2m
Each can be selected within the range of m, and the number of cords to be inserted therein can be selected within the range of 4 to 16. Furthermore, when the ribbon-like reinforcing layer is wound in an overlapping state, the distance between both ends of the overlap cord is 1.
It is preferable to carry out the overlap within a range of about 1/4 to 2/3.

According to this ribbon-shaped reinforcing layer 5, when the ribbon-like reinforcing layer 5 is wound in a partially overlapping state, the fluidity of the coating rubber 2 at the side end portions 4 of the ribbon-like reinforcing layer 5 is controlled by the driving of the reinforcing cord 1. Since the density is sufficiently small, each side end portion 4 has its fluidity and comes into close contact with each of the upper and lower adjacent surface members as a whole. , air trapping in the overlapping windings is very effectively prevented.

The ribbon-shaped reinforcing layer 15 shown in FIG. 1(b) has five reinforcing cords arranged at equal intervals in the central portion 3, and the side end portions 4 are made of only rubber. Since the rubber 2 in No. 4 can flow almost unhindered by the reinforcing cord 1, the fluidity of the rubber 2 in the overlapped winding portion can be further increased to more effectively prevent the formation of air pockets there. It can be prevented.

Further, the ribbon-shaped reinforcing layer 25 shown in FIG. 1(c) has all five reinforcing cords 1 disposed in the central portion 3, and both end portions 4 are formed of only the rubber 2.
In addition, the rubber 2 is formed to become gradually thinner toward the side edges, and is tapered in the figure. In this reinforcing layer 25, in addition to the fact that the reinforcing cord 1 is not present at all in the side end portion 4, the side end portion itself has a thin shape similar to the shape of the air pockets d and e in FIG. , the generation of air pockets in each side end portion 4 can be more effectively prevented. In this example, it is preferable that the width of the side end portion/distance between cord centers is 1 or more and 4 or less.

FIG. 2 is a cross-sectional view in the width direction of a pneumatic radial tire showing an example in which an auxiliary layer is formed using the ribbon-like reinforcing layer shown in FIG. 1(c). In the figure, 31 indicates a pair of left and right bead rings, 32 indicates a radial carcass extending toroidally between both bead rings, and 33 indicates a belt consisting of at least two belt layers. In this example, the belt 33 is composed of two belt layers 33a and 33b, and the respective belt layers 33a and 33b extend at a relatively small angle with respect to the tire equatorial plane XX and are mutually connected to each other. In each of the intersecting cords, for example, steel cords, the auxiliary layer 34 is formed by spirally winding the ribbon-shaped reinforcing layer 25 at a position adjacent to the outer circumferential side of the belt 33 so as to cover the entire width of the belt. form,
Only the portion of this auxiliary layer 34 located in the belt side region is formed with a winding portion of the ribbon-like reinforcing layer 25 in an overlapping state, for example, with a 1/2 overlap between the ends of the cord.

[0015] Therefore, here, the winding pitch of the ribbon-like reinforcing layer 25 is small in the side regions of the belt 33, and large in the central region. Note that here, the ribbon-shaped reinforcing layer 2
The winding pitch of 5 extends from the central area to the side areas, insofar as it is smaller in the side areas and larger in the central area;
It is of course possible to change the winding pitch gradually or abruptly as required, but in particular the winding pitch in the central region of the belt should not be increased beyond that shown in the illustrated example, i.e. ribbon-like reinforcement. It is preferable to select a pitch that does not create a gap between layers, in order to prevent air pockets due to differences in level between adjacent ribbon-shaped reinforcing layers.

By the way, in the overlapping winding portion 35 in the belt side region, each side end portion 4 flows smoothly based on the rubber fluidity inherent to the ribbon-shaped reinforcing layer 25. As is clear from FIG. As a result, the risk of peeling of the auxiliary layer 34 and the tread rubber 36 can be sufficiently eliminated, and the high-speed durability of the tire can be greatly improved. Incidentally, when the above-mentioned tire and the tire according to the prior art were inspected for the presence or absence of air pockets after vulcanization, it was found that in the above-mentioned invention tire, the overlap winding portion 35, the belt 33, and the tread rubber were particularly damaged. 36, no air pocket could be detected between the two.
In the conventional tire, several small air pockets were detected in similar locations.

[0017]

Thus, according to the present invention, it is possible to sufficiently prevent the formation of air pockets in the overlapped winding portion of the ribbon-shaped reinforcing layer, and to greatly improve the high-speed durability of the tire.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view in the width direction illustrating a ribbon-shaped reinforcing layer of the present invention.

FIG. 2 is a cross-sectional view in the width direction illustrating the pneumatic radial tire of the present invention.

FIG. 3 is a cross-sectional view in the width direction illustrating a conventional ribbon-shaped reinforcing layer.

FIG. 4 is a cross-sectional view showing a state in which the ribbon-shaped reinforcing layer shown in FIG. 3 is wound in an overlapping manner.

[Explanation of symbols]

1 Reinforcement cord 2 Rubber 3 Central part 4 Side end part 5, 15, 25 Ribbon-shaped reinforcement layer 31 Bead core 32 Radial carcass 33 Belt 33a, 33b belt layer 34 Auxiliary layer 35 Overlap winding part 36 Tread rubber

Claims (4)

[Claims] 1. A ribbon-shaped reinforcing layer formed by rubber-coating a plurality of reinforcing cords, the reinforcing cord implantation density at at least one side end portion being smaller than that at the central portion. 2. The ribbon-shaped reinforcing layer according to claim 1, wherein at least one side edge portion is formed only of rubber, and the thickness becomes gradually thinner toward the side edge. 3. On the radially outer peripheral side of at least two belt layers each consisting of cords that extend at a relatively small angle to the tire equatorial plane and intersect with each other, at least one side of both belt layers. A pneumatic radial tire comprising a ribbon-shaped reinforcing layer according to claim 1 or 2 wound around the area in an overlapping manner to constitute an auxiliary layer. 4. The auxiliary layer is composed of a ribbon-shaped reinforcing layer that covers the entire widthwise direction of at least two belt layers, and the winding pitch of the ribbon-shaped reinforcing layer is set at a central area of the belt layer. 4. A pneumatic radial tire according to claim 3, which is larger and smaller in the side regions.