Tire intended for heavy loads and to be inflated to a high press

Details Tire intended for heavy loads and to be inflated to a high press Tire intended for heavy loads and to be inflated to a high press

1993-06-24

1995-01-10

Ball, Michael W.

Resilient tires and wheels

Tires, resilient

Pneumatic tire or inner tube

152550, 152552, 152554, B60C 902

Patent

active

053798201

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The present invention relates to tires with radial carcass reinforcement intended to bear heavy loads and to be inflated to relatively high pressures, and particularly to tires suited for use as airplane tires.
The radial carcass reinforcements of such tires generally have several plies of textile cables which are anchored in each bead to at least one bead wire and generally to a single bead wire. The reinforcement elements of these tires are wound around said bead wire from the inside to the outside, forming upturns the ends of which are spaced radially from the axis of rotation of the tire. The severe conditions under which airplane tires are used, and, in particular, the overloads imposed, are such that the fatigue strength endurance of the beads is slight, particularly at the place of the ends of the upturns of the carcass reinforcement.
A substantial improvement in performance is obtained by separating the plies of the carcass reinforcement into two groups. The first group comprises the axially inner carcass reinforcement plies in the region of the beads, these plies being then wound around a bead wire in each bead from the inside to the outside of the tire. The second group is formed of at least one axially outer ply in the region of the beads, which ply is generally wound around the bead wire going from the outside to the inside of the tire.
Such arrangements are known and are shown, for instance, in U.S. Pat. No. 4,244,414 (FIG. 2).
The fatigue strength of the beads formed in this manner is, however, still insufficient and this lack of fatigue strength results in separations between the outer plies and/or the last outer ply and the rubber which covers it, this rubber forming the outside of the bead and/or of the side wall; these separations are generally accompanied by fatigue of the cables of these plies.


SUMMARY OF THE INVENTION

The present invention proposes a solution in order to improve the life of the beads of the tires concerned while using bead wires having inside diameters as small as possible, which permits better resting on the flanges of the rim, this solution comprising arranging the edge (edges) of the axially outer ply (plies) between the upturns of the axially inner plies, without winding around the bead wires.
The present invention relates to a tire, intended for heavy loads and to be inflated to high pressures, particularly suited for use as an airplane tire, having a tread, a crown reinforcement, and a radial carcass reinforcement comprising at least two axially inner plies of textile cords, wound around a bead wire in each bead from the inside to the outside of the tire and then forming upturns, and at least one axially outer ply of textile cords superimposed on the inner plies below the crown reinforcement and separating said plies in the beads in order to extend along the upturns in the beads, characterized by the fact that each of the outer plies has its edges arranged between the upturns of two adjacent inner plies and by the fact that the ends of the axially outer ply (plies) are disposed axially to the outside of a straight line perpendicular to the axis of rotation of the tire and tangent to the circle circumscribed on the bead wire, axially on the outer side thereto, while remaining situated radially to the outside of a straight line parallel to the axis of rotation, tangent to the circles circumscribed on the cross sections of the bead wires at their points radially closest to the axis of rotation.
In the case of a plurality of axially outer plies, a uniform distribution of the tensions on these plies is also obtained. For the same purpose, the ends of the upturns of the axially inner plies are preferably spaced from the base of the bead by a height at least equal to 0.25 times the height of the tire mounted on its service rim, inflated to its service pressure, said height being measured at the level of the center line of the radial carcass reinforcement.
In the same way, the said upturns have radially spaced ends, the difference between

REFERENCES:
patent: 1393952 (1921-10-01), Miller
patent: 3386486 (1968-06-01), Kovac et al.
patent: 3638705 (1972-02-01), Devienne et al.
patent: 4029137 (1977-06-01), Suydam
patent: 4177852 (1979-12-01), Merli et al.
patent: 4244414 (1981-01-01), Uemura et al.
Patent Abstracts of Japan, vol. 9, No. 67 (M-366) (1790) 27 Mar. 1985 (54) neumatic Tire (Sumitomo Gomu Kogyo K.K. Appln. No. 58-71953.

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