JPS59216704A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To improve the uniformity of a tire as well as to reduce vibrations in time of running at a high speed, by forming the plane sight form of an end part in a splice part of a belt cover layer into a jagged form each. CONSTITUTION:This tire is made up of a pair of symmetrical bead parts 1 and 2, a pair of symmetrical sidewall parts 3 leading to the bead part 1 and a tread part 3 situated between these sidewalls. A carcass layer 4 consisting in a cord angle of 70-90 degrees to the tire circumferential direction is installed in position astride between these symmetrically paired beads 1 and 1. Plural belt layers 5 crossed at a cord angle of 10-30 degrees to the tire circumferential direction are arranged on the carcass layer 4 at the tread part 3. In addition, a belt cover layer 6, which sets a heat absorbent cord to a zero degree in the tire circumferential direction is installed on an outermost layer of the belt layer 5 whereby the plane sight form of an end part at the splice part 61 is formed into a jagged form each.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a pneumatic radial tire having a structure in which a single layer of a belt cover is arranged on the outermost layer of a belt layer, and a cord made of a heat-shrinkable material is set at approximately 0° with respect to the circumferential direction of the tire. The present invention relates to a pneumatic radial tire that improves uniformity and reduces vibration, particularly during high-speed running, to improve riding comfort.

Conventionally, radial tires with excellent high-speed performance, especially steel radial tires, have been equipped with a cord made of heat-shrinkable material around the tire circumference on the outermost layer of the belt layer in order to suppress the standing wave phenomenon in the tread during high-speed running. A single layer of the belt cover is arranged at approximately Oo with respect to the direction.

However, when the tire is being manufactured, this single layer belt cover is
Since the splice part 61 exists, and this splice part 61 has locally high rigidity as shown in FIG. As a result of various studies, it has become clear that this poor uniformity is one of the causes of vehicle vibration and worsens ride comfort.

The present invention was developed as a result of studies to solve the above-mentioned problems.

Therefore, an object of the present invention is to improve the uniformity of a tire equipped with a single layer of belt cover by devising the structure of the splice part in the single layer of belt cover, and in particular to reduce vibration during high-speed running and improve riding comfort. An object of the present invention is to provide a pneumatic radial tire that can be obtained.

That is, the present invention comprises a pair of left and right bead portions, a pair of left and right sidewall portions connected to the bead portions, and a tread portion located between the sidewall portions, and a tread portion located between the pair of left and right bead portions in the circumferential direction of the tire. The cord angle is 70
A carcass layer having an angle of 10° to 90° is installed, and a plurality of belt layers intersecting each other at a cord angle of 10° to 30° with respect to the tire circumferential direction are disposed on the carcass layer in the tread portion, and the belt layer In a pneumatic radial tire in which a single layer of belt cover is arranged on the outermost layer of the belt cover, a cord made of a heat-shrinkable material is arranged approximately Oo in the circumferential direction of the tire. The gist of the present invention is a pneumatic radial tire characterized by having a concave and convex shape.

First, the progress that led to the present invention will be explained along with experimental examples.

The inventors of the present invention have devised the structure of the splice portion so that when the stiffness changes locally in the splice portion of the single layer of the belt cover, the amount of change does not change suddenly but smoothly. Focusing on the fact that the uniformity of the tire can be improved, as shown in FIG. The uniformity of each tire was measured by forming each tire into an uneven shape in plan view.

The uniformity measurement was carried out in accordance with JASOC607.
In addition, in each experimental example explained below, 195/7011R
14 steel radial tires were used, and the experimental results were summarized as the average value of 15 tires.

Example In this experiment, the splice portion 61 of the belt cover layer 6 was
Each end of the belt cover layer in , that is, the upper end 6
U and the lower end 6d were each formed into an uneven shape in plan view, and the number of uneven portions A was varied to measure the uniformity of the tire, and the experimental results shown in FIG. 10 were obtained. .

In FIG. 10, the vertical axis represents the uniformity of the tire, and the horizontal axis represents the number of uneven portions A.

Note that in the figure, the ○ mark indicates RFV, and the * mark indicates LFV.

In addition, in this experiment, as shown in FIG. , the splice measurement of the splice portion 6a is
Assuming A/L=0.5, there is C.

As is clear from FIG. 1O, the uniformity of the tire is improved even by arranging only one uneven portion A in the splice portion 61, and as the number of uneven portions A increases, a tendency towards saturation 1 is observed.

As described above, if each end of the belt cover layer in the splice portion 61 of the belt cover N6, that is, the upper end 6u and the lower end 6d, is formed into an uneven shape in plan view, the uneven This is because within the range A, the rigidity of the splice portion 61 of the belt cover layer 6 can be smoothly changed in the circumferential direction as shown in FIGS. 4(C) and 5(C).

Example In this experiment, the size of the above-mentioned uneven portion A, that is, the value of l/ was varied, and the uniformity of the tire was measured.

FIG. 11 shows the experimental results, with the vertical axis representing the uniformity of the tire and the horizontal axis representing the value of N/L.

Is the O mark in the diagram R1? ν is shown, and the * mark shows LFV.

In addition, in this experiment, as shown in FIG.
=l.

As is clear from FIG. 11, the uniformity of the tire is determined by the size of the uneven portions formed at each end of the belt cover layer 6 at the splice portion 61, that is, the upper end portion 6u and the lower end portion 6d. The larger the value, the better it tends to be.

As mentioned above, the splice portion 61 of the belt cover layer 6
Each end of the belt cover layer in , that is, the upper end 6
When an uneven portion is formed on u and the lower end 6d, the unevenness dimension l of the uneven portion A is set to 25 with respect to the splice scale.
% or more, the rigidity of the splice portion 61 of the belt cover N6 can be changed smoothly in the circumferential direction, and the uniformity of the tire can be improved.

Furthermore, when β/L is set to 1 or more, the stiffness no longer exceeds 2.0 times as shown in Figure 5 (cl) in any radial cross section of the splice part. The more the splice becomes, the smaller the maximum stiffness of the splice portion becomes (approaching 1.0 times) and the change in stiffness becomes smoother, so that the effect of improving uniformity can be further enhanced.

On the other hand, considering the ease of handling and productivity of the belt cover layer in the molding process, the number of uneven portions is preferably 1 to 3, and the l/L value is also preferably in the range of 0.25 to 2.

After all, the value of β/L is 0.2 when the number of uneven portions A formed on the splice portion 61 is small, for example, 1 to 2.
It is preferable to set it in the range of 5 to 2.0, and when the number of uneven parts A is large, for example, when the number of uneven parts is 20 to 40, It/L is set in the range of 0.1 to 0.2. It is preferable to set it to .

Hereinafter, the present invention will be specifically described by way of examples with reference to the drawings.

3 to 9 show embodiments of the present invention, FIG. 3 is a partially cutaway perspective explanatory view of a pneumatic radial tire according to the embodiment of the present invention, and FIGS. 4(a) to (C) ) shows the main part of the first embodiment, that is, the splice part of one layer of the belt cover,
(a) is a plan view explanatory diagram, (b) is a side view explanatory diagram of the same as above, (
C) is a rigidity distribution diagram of the same as above, FIGS. 5(a) to (C1 are main parts of the second embodiment, that is, the splice part of one layer of belt cover), (a) is an explanatory plan view, and (b) is a side view of same as above. (C1 is the same stiffness distribution diagram as above, FIG. 6 is a plan view explanatory view showing the main part of the third embodiment, that is, the splice part of the single layer of the belt cover, and FIG. 7 is the main part of the fourth embodiment, that is, the splice part of the single layer of the belt cover. FIG. 8 is an explanatory plan view showing the main part of the fifth embodiment, that is, the splice part of one layer of belt cover. FIG. 9 is an explanatory plan view of the main part of the sixth embodiment, that is, the splice part of one layer of belt cover. FIG.

In the figure, E denotes a pneumatic radial tire according to an embodiment of the present invention, which includes a pair of left and right bead parts, a pair of left and right sidewall parts 2 connected to the bead parts 1, and a space between the sidewall parts 2. It consists of a tread portion 3 located at
A carcass layer 4 in which the angle of the cord 4a with respect to the tire circumferential direction is substantially 90° is installed between the pair of left and right bead portions 1, and a cord with respect to the tire circumferential direction is disposed on the carcass layer 4 in the trend portion 3. The angle of 5a is 10”~3
A plurality of belt layers 5 intersecting each other at 0° are arranged, and a belt cover layer 6 is further provided on the outermost layer of the belt layers 5, with cords 6a made of a heat-shrinkable material set at approximately Oo with respect to the tire circumferential direction. It is configured by arranging.

In the present invention, particularly, the belt cover N
The ends of the belt cover single layer in the splice portion 61 of No. 6, that is, the upper end 6u and the lower end 6d, are each formed into an uneven shape in plan view.

Further, to explain this structure, in this embodiment, the carcass layer 4 is composed of two layers: an outer carcass layer 4u and an inner carcass N4d. Rayon cord is used for the cord 4a of each carcass layer,
The cord angles with respect to the tire circumferential direction are each 90''.

In this embodiment, the belt R5 is also composed of two layers: an outer heald layer 5u and an inner belt JW5d. Steel cords are used for the cords 5a of each of these belts H, and the cords intersect with each other at an angle of 24 degrees with respect to the tire circumferential direction.

Furthermore, the outermost layer of the belt layer 5 described above, that is, the outer side (7)
In this embodiment, the single layer 6 of the belt cover disposed on the heald layer 5u is arranged as shown in FIG. °It's Toshishita.

2+8+ (In the first embodiment shown in bl, each end of the belt cover layer 6 at the splice portion 61, that is, the upper end portion 6u and the lower end portion 6d, has a triangular shape in plan view. This is an example in which two uneven portions A are arranged with equal pinching over the entire width of one layer 6 of the belt cover.

Further, in the second embodiment shown in FIG. 5 (al fb), each end of the belt cover single layer at the splice portion 61 of the heald cover single layer 6, that is, the upper end 6u and the lower end 6d,
This is an example in which each of the belt cover layers 6 has a triangular shape in plan view, and one uneven portion A is arranged over the entire width of the belt cover layer 6.

Further, in the third embodiment shown in FIG. 6, each end of the belt cover layer at the splice portion 61 of the heald cover layer 6, that is, the upper end portion 6u and the lower end portion 6d, has a triangular shape in plan view. This is an example in which four uneven portions A are arranged with equal pinching over the entire width of one layer 6 of the belt cover.

In each of the above-mentioned embodiments, the shape in plan view is triangular, and the concave and convex portions A are arranged with equal pinches over the entire width of the belt cover layer 6, but this is illustrated in FIGS. As in the fourth to sixth embodiments shown in FIG.
The splices do not necessarily have to be arranged in an even pinch over the entire width of the bell l-cover N6, and the entire splice portion may be inclined obliquely as in the sixth embodiment shown in FIG.

As described above, in the present invention, the end portions of the splice portion of the single-layer belt cover are each formed into an uneven shape in plan view, so that the uniformity of the tire in which the single-layer belt cover is arranged can be greatly improved, and in particular, It is possible to reduce vibrations during high-speed driving and improve riding comfort.

[Brief explanation of the drawing]

Figures 1 and 2 show the main part of a conventional pneumatic radial tire, that is, the splice part of one layer of the belt cover.
The figure is a perspective explanatory view, Figure 2+8+ is a plan view explanatory view, (bl
is a side view explanatory diagram of the same as above, (C1 is a stiffness distribution diagram of same as above. Fig. 3 to Fig. 9 show an embodiment of the present invention, and Fig. 3 shows a pneumatic radial tire according to an embodiment of the present invention. A perspective explanatory view with a part cut away, FIG. An explanatory diagram, (C) is a rigidity distribution diagram as above, FIGS. FIG. 6 is an explanatory plan view showing the main part of the third embodiment, that is, the splice part of one layer of the belt cover. FIG. 7 is the main part of the fourth embodiment. That is, FIG. 8 is an explanatory plan view showing the splice portion of one layer of the belt cover, FIG. 8 is an explanatory plan view showing the main part of the fifth embodiment, that is, the splice part of the one layer belt cover, and FIG. 9 is the main part of the sixth embodiment, that is, the belt cover. It is a plan view explanatory diagram showing a splice part of one layer.Furthermore, Fig. 10 and Fig. 11 are diagrams showing the results of experiments, respectively.1...Bead part 2...Side wall part 3...Trend Part 4... Carcass layer 5... Belt layer 6... Belt cover first layer 61... Splice department agent Patent attorney Small credit - Patent attorney Kensho Noguchi Patent attorney Kazuhiko Saishita'Kg 1 Figure 3rd day 4L 乃゛50 (G) (b: )(C) Figure 6 Figure 7 Figure 81'J'' Figure 9 Figure 10 Port 12345 Number of uneven parts 110 0 0.5 1.0 1.5 2. Ot/L

Claims (1)

[Claims] Consisting of a pair of left and right bead parts, a pair of left and right sidewall parts connected to the bead parts, and a trend part located between the sidewall parts, the cord angle between the pair of left and right bead parts with respect to the tire circumferential direction is 70. A carcass layer having an angle of 10° to 90° is installed, and a cord angle of 10° to 30° to the tire circumferential direction is mounted on the carcass layer in the trend part.
A pneumatic tire in which a plurality of belt layers intersecting at 0" are arranged, and a single layer of a belt cover is arranged on the outermost layer of the belt layers, and a cord made of a heat-shrinkable material is arranged at approximately 0 degrees with respect to the tire circumferential direction. 1. A pneumatic radial tire, characterized in that the end portions of the splice portion of the single layer of the belt cover are each formed into an uneven shape in plan view.