JPS62273837A - Pneumatic radial tire for passenger car - Google Patents

Abstract

PURPOSE:To contrive an improvement in uniformity without deteriorating durability at high speed, by providing a plurality of notches on a belt reinforcement layer. CONSTITUTION:A plurality of notches 8 are provided on a belt reinforcement layer 7 by aiming at extension of the belt reinforcement layer 7 uniformly in the circumferential direction to a lifting power to be given during vulcanization, in a pneumatic radial tire where the belt reinforcement layer 7 constituted of a fiber cord and steel cord, etc. is arranged annularly, on a belt layer 4 composed of a metallic cord in the circumferential direction extending over the central region or both end regions of the belt layer or the complete width of the belt layer. The notch 8 may be provided either penetrating the belt reinforcement layer 7 from the surface to the backside, or not. Although the size and number of the notches 8 are not specified, as strength of the belt reinforcement layer 7 is deteriorated excessively when the notches 8 are tool large or too many, they should be decided within a range where the strength is not deteriorated extremely.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a pneumatic radial tire for passenger cars that has improved high-speed durability and tire uniformity.

[Prior art]

Conventionally, radial tires in which a belt layer made of metal cords is placed on the carcass layer in the tread section have excellent wear resistance, but the weight of the tread section is lower than when using a belt layer made of fiber cords. Because it is extremely large, standing waves tend to occur, making it unsuitable for high-speed driving. Here, the standing wave refers to residual flexure on the tire contact surface during high-speed driving. In other words, at relatively low speeds, the deflection that the tire receives on the ground contact surface recovers as soon as the tire leaves the ground contact surface, but as the speed gradually increases, the internal pressure that acts as a restoring force acts on the tread. When the magnitude of the centrifugal force increases and reaches a certain speed, this finally becomes an excitation force, and waves are generated from the portion away from the ground contact surface, propagating along the circumferential direction of the tread portion, and remaining as a result.

When this standing wave begins to occur, heat generation in that part increases rapidly, and separation failure occurs due to this heat.

Therefore, in order to suppress standing waves, that is, to improve high-speed running performance, on top of the belt layer made of metal cords, in the central region or both end regions of the belt layer, or over the entire width of the belt layer. 2. Description of the Related Art A tire structure has been proposed in which a belt reinforcing layer made of nylon cord, steel cord, etc. is arranged in an annular manner in the circumferential direction of the tire to suppress elongation of the belt layer due to high-speed rotation of the tire.

However, because the outer circumference of an unvulcanized tire before vulcanization is smaller than the inner circumference of the vulcanization mold, tires with such a belt reinforcement layer are subjected to lift during vulcanization, and the splice This causes unevenness on the circumference of the tire, deteriorating uniformity (particularly radial force variation (RFV)). In particular, the degree of deterioration is large for 2-split molds with high lift rates.

[Purpose of the invention]

An object of the present invention is to provide a pneumatic radial tire for passenger cars that is equipped with a belt reinforcing layer and has excellent high-speed durability and uniformity.

[Structure of the invention]

For this reason, the present invention provides a tire with a belt reinforcing layer made of fiber cords, steel cords, etc., on the belt layer made of metal cords, in the central region or both end regions of the belt layer, or over the entire width of the belt layer. In a pneumatic radial tire arranged annularly in the circumferential direction, a plurality of cuts are provided in the belt reinforcing layer for the purpose of stretching the belt reinforcing layer uniformly in the circumferential direction against the lift received during vulcanization. This article focuses on pneumatic radial tires for passenger cars, which are characterized by their characteristics.

Hereinafter, the configuration of the present invention will be explained in detail with reference to the drawings.

FIG. 2 is a radial half-sectional explanatory diagram of an example of a pneumatic radial tire for a passenger car according to the present invention.

In Fig. 1, between a pair of left and right bead wires 3°3,
A carcass layer 4 having a cord angle of substantially 90'' with respect to the tire circumferential direction is mounted, and a belt layer 5 made of metal cords is placed on top of this carcass layer 4 in the tread portion l.
are arranged in an annular manner in the circumferential direction of the tire. On both end regions of the belt layer 5, a belt reinforcing layer 7 is arranged annularly in the tire circumferential direction. 2 represents a sidewall portion, and 6 represents a bead filler.

The belt reinforcing layer 7 may be arranged in the central region of the belt layer 5 instead of at both end regions of the belt layer 5, or may be arranged over the entire width of the belt layer 5. The cord angle of the belt reinforcing layer 7 is approximately 0'' (
parallel).

FIG. 2 is an explanatory plan view of the belt reinforcing layer 7. A plurality of cuts 8 are provided in the belt reinforcing layer 7. This cut 8 may or may not penetrate from the front surface to the back surface of the belt reinforcing layer 7. The size and number of the cuts 8 are not specified, but if they are too large or too many, the strength of the belt reinforcing layer 7 will decrease excessively, so care should be taken to determine the size and number within a range that does not reduce the strength too much. be.

〔Effect of the invention〕

As explained above, according to the present invention, since a plurality of cuts are provided in the belt reinforcing layer, it is possible to sufficiently improve the uniformity of a tire having a belt reinforcing layer without reducing high-speed durability. .

[Brief explanation of drawings]

FIG. 1 is a radial half-section wAWWI of an example of a pneumatic radial tire for a passenger car according to the present invention, and FIG. 2 is an explanatory plan view of a belt reinforcing layer of the tire. 1...Tread part, 2...Side wall part, 3...
... Bead wire, 4... Carcass layer, 5... Belt layer, 6... Bead filler, 7... Belt reinforcement layer, 8... Cut, 9... Cord.

Claims (1)

[Claims] On the belt layer made of metal cords, in the central region or both end regions of the belt layer, or over the entire width of the belt layer,
1. A pneumatic radial tire for a passenger car in which a belt reinforcing layer is arranged annularly in the circumferential direction of the tire, the pneumatic radial tire comprising a plurality of cuts in the belt reinforcing layer.