JPH03189207A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To provide a uniformly distributed grounding pressure and enhance the stability in maneuvering by forming a belt reinforcing layer from at least three sub-layers consisting of different organic fiber cords, wherein their widths lie within respective specified ranges, and covering the edges of each belt layer on both sides with such belt reinforcing layers. CONSTITUTION:In a pneumatic radial tire concerned, the edges of an upper and a lower belt layer 4 are covered with belt reinforcing layer 5. Each belt reinforcing layer 5 consists of laminated three sub-layers 5-1 thru 5-3 having the least, medium, and largest width, respectively. Among them the largest sub-layer 5-3 is formed from a left and a right layer having a width not more than 50% of the belt layer max. width W, or one layer having the belt layer max. width W. The least sub-layer 5-1 is formed from a left and a right layer having a width no less than 10mm. The medium sub-layer 5-2 is formed from a left and a right layer having an intermediate width between those of the named sub-layers 5-3, 5-1.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a pneumatic radial tire that has improved high speed and durability by arranging a belt reinforcing layer on the belt layer, and particularly relates to a pneumatic radial tire with a large ground contact width. Related to improvement of flat radial tires.

[Prior art] A pneumatic radial tire for high-speed running has a belt layer made of high-modulus steel cord, aramid fiber cord, etc. in the trend part, and both edge parts of this belt layer are covered with belts made of nylon cord, etc. Coating with a reinforcing layer provides high-speed durability.

In order to improve steering stability in this radial tire, in a flat tire with a larger ground contact width, as the aspect ratio increases, the ground pressure applied to the shoulder part of the tread increases more than the center part of the tread, and the ground contact pressure distribution tends to be uneven. As a result, there has been a problem in that the steering characteristics and effectiveness of the steering wheel during high-speed driving are reduced, and the steering stability feeling is deteriorated.

[Problem to be solved by the invention]

An object of the present invention is to provide a pneumatic radial tire in which at least both edges of the belt layer of the trend part are covered with a belt reinforcing layer, which has uniform ground pressure distribution and improved handling stability. It is about providing.

[Means to solve the problem]

An object of the present invention is to arrange at least two belt layers in the tread portion, the belt cords of which intersect with each other along the circumferential direction of the tire, In a radial tire coated with a belt reinforcing layer made of organic fiber cords having an angle of substantially 0°, the belt reinforcing layer is comprised of at least three different widths: a maximum belt reinforcing layer, a minimum belt reinforcing layer, and an intermediate belt reinforcing layer. The maximum belt reinforcing layer consists of a pair of left and right layers each having a width of 50% or less of the maximum belt layer width W, or one layer having a maximum belt layer width W, and the minimum belt reinforcing layer has a width of 10 mm or more. This can be achieved by comprising a pair of left and right layers having the same width, and the intermediate belt reinforcing layer having a width intermediate between the largest belt reinforcing layer and the smallest belt reinforcing layer.

FIG. 1 is a schematic cross-sectional view showing one example of a belt structure provided on the tread portion of the tire of the present invention.

As shown in the figure, the upper and lower two belt layers 4 are provided with three layers each for a pair of left and right sides so as to cover the edge portions E on both sides.
Belt reinforcing layers 5 of different widths are arranged.

In the belt layer 4, cords having a high elastic modulus such as steel cords or aramid fiber cords are inclined with respect to the tire circumferential direction, and intersect between two adjacent layers. Further, the belt reinforcing layer 5 is constituted by organic fiber cords such as nylon or the like arranged substantially at θ'' in the tire circumferential direction.

As shown in the figure, the three-layer belt reinforcing layer 5 is
From the side in contact with, the minimum belt reinforcing layer 5-1 with the minimum width,
The belt reinforcing layers 5-2 are arranged in such a manner that their widths gradually increase in the order of the intermediate belt reinforcing layer 5-2, which has an intermediate width, and then the largest belt reinforcing layers 5-3, which have the largest width. It is most preferable to arrange these at least three belt reinforcing layers in stages as shown in FIG. 1, but the order is not limited to this. For example, as shown in FIG. Reinforcement layer 5
-2 and the minimum belt reinforcing layer 5-1 may be arranged in the opposite order, and the minimum belt reinforcing layer 5-1 may be arranged in the middle. Further, the maximum belt reinforcing layer 5-3 may have a single layer structure with continuous left and right sides as shown in FIG.

In such a belt structure, the maximum belt reinforcing layer 5-
When a pair of left and right belt layers is provided, the width of the belt layer 3 needs to be within 50% of the maximum width W of the belt layer 4 on each side. Also, -
When making a full cover with only layers, the width should be equal to the maximum width W of the belt layer. Further, the minimum belt reinforcing layer 5-1 needs to have a width of 10 mm or more per side. Further, the intermediate belt reinforcing layer 5-2 has a width intermediate between the minimum belt reinforcing layer 5-1 and the maximum belt reinforcing layer 5-3.

By covering the belt layer with at least three types of belt reinforcing layers with different widths, the ground pressure, which tends to be low in a part of the center when the ground contact width is increased, is increased, and the ground pressure is increased over the entire tread width. It is possible to make the ground pressure distribution almost uniform.

In other words, in the case of conventional tires, the tread contact pressure shape is E.
-E' is the circumferential direction of the tire, the tire of the present invention has a shape as shown by S' in FIG.
It can be shaped as shown by S in the figure. Further, by making the tread contact pressure uniform in this way, it is possible to improve the feeling of steering stability while ensuring high-speed performance based on the belt reinforcing layer. Such an effect can be particularly noticeable when the aspect ratio is 60 or less.

〔Example〕

Three types of tires of the present invention, I and II, and a conventional tire, each having a belt structure consisting of the following three layers and having different widths of the belt reinforcing layer in this belt structure, were prepared.

Belt structure: Fig. 1 Maximum width of belt layer W = 200mm Minimum belt reinforcement layer 5-1 = 30mm 30mm Medium reinforcement layer 5-2 = 40mm Maximum belt reinforcement layer 5-3 = 50mm Belt structure: Fig. 2 Maximum width of belt layer W = 200mm Minimum belt reinforcement layer 5-1 = 40mm 40mm middle reinforcement layer 5-2 = 30mm Maximum belt reinforcement layer 5-3 = 50mm Belt structure: In Figure 1, the intermediate belt reinforcing layer has the same full cover as the maximum belt reinforcing layer Maximum width W of belt layer = 200 mm Minimum belt reinforcing layer 5-1 = 30 mm Intermediate belt reinforcing layer 5- 2 (Full Cover) = 200 mm Maximum Belt Reinforcement Layer 5-3 (Full Cover) = 200 mm A steel cord was used for the belt layer, and a nylon cord was used for each cord of the belt reinforcement layer.

Also, the size of these tires is the same 225
It was set to 150R1692ν.

These tires are sporty tires with a displacement of 3,000cc.
The steering stability feeling was evaluated by five test drivers using a 10-point scale using a 10-point scale, and the average value is shown in the table.

In addition, when the ground contact shape of the tread portion of each tire was confirmed, the present invention tires f and ■ had the shape shown in FIG. 4, and the conventional tire had the shape shown in FIG. 5.

(Margins below on this page) From the table, it can be seen that the tires of the present invention ■ and ■ both have a more uniform ground pressure distribution on the tread surface than conventional tires, so the feeling of steering stability on dry and wet roads is improved. I can see that you are doing it.

[Effects of the Invention] According to the present invention, the belt reinforcing layer covering at least the artist/knot portion of the belt layer is reinforced with at least three types of organic fiber cords having mutually different widths and defined within a specific range. Since it is composed of layers, the ground pressure distribution can be made uniform, and the steering stability feeling can be improved. Particularly, high effects can be exhibited in flat radial tires with a wide contact width and an aspect ratio of 60% or less.

[Brief explanation of drawings]

1, 2 and 3 are schematic cross-sectional views showing the belt structure in the trend section of the tire of the present invention, respectively. It is a schematic diagram showing a shape. 4...Belt layer, 5...Belt reinforcement layer, 5-1...
- Minimum belt reinforcement layer, 5-2... intermediate belt reinforcement layer,
5-3... Maximum belt reinforcement layer.

Claims (1)

[Claims] At least two belt layers whose belt cords intersect with each other along the tire circumferential direction are arranged in the tread portion, and at least both edge portions of the belt layers are arranged so that the cord angle with respect to the tire circumferential direction is substantially In a radial tire covered with a belt reinforcing layer made of 0° organic fiber cord, the belt reinforcing layer is composed of a maximum belt reinforcing layer, a minimum belt reinforcing layer, and an intermediate belt reinforcing layer having at least three different widths, and The largest belt reinforcing layer consists of a pair of left and right layers having a width of 50% or less of the belt layer maximum width W, or a single layer having a belt layer maximum width W, and the minimum belt reinforcing layer consists of a pair of left and right layers having a width of 10 mm or more. A pneumatic radial tire comprising a pair of left and right layers, wherein the intermediate belt reinforcing layer has a width intermediate between the largest belt reinforcing layer and the smallest belt reinforcing layer.