Resilient tires and wheels – Tires – resilient – Pneumatic tire or inner tube
Patent
1992-12-17
1994-06-28
Ball, Michael W.
Resilient tires and wheels
Tires, resilient
Pneumatic tire or inner tube
152542, 152545, 152552, B60C 15024, B60C 1505
Patent
active
053238303
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a tire with radial carcass reinforcement anchored in each bead with at least one bead ring, each bead having a seat which is inclined with respect to the axis of rotation of the tire by an angle of more than 5.degree., and generally at least equal to 15.degree..+-.1.degree.. Radially on top of the radial carcass reinforcement, there is a crown reinforcement consisting of one or more plies of cords or cables.
In each bead, axially to the outside of the upturn of the carcass ply, there are arranged, in known manner, one or more plies of textile or metal cords or cables oriented at a slight angle with respect to the circumferential direction of the tire, the radially outer end of said ply or plies being located either above or below the end of the upturn of the carcass reinforcement, the radially inner end being possibly located in the toe of the bead.
This reinforcement armature in each bead has the function of stiffening the rubber mix present axially to the outside of the upturn of the carcass reinforcement. It gives rise to separations with ruptures of rubber at its radially outer end. Furthermore, in view of the profile of the base of the bead, which is designed as a function of the profile of the service rim on which the tire is mounted, the contact pressure between the bead and the rim is very high between the inclined portion of the base of the bead and the inclined seat of the rim. The same is true between the flange of the rim and the corresponding portion of the tire, the tire being inflated at its operating pressure but not under load. On the other hand, the part of the bead located immediately above the rim flange, and not in contact with said flange when the tire is inflated, assumes contact with the rim flange under the effect of the load applied to the tire from the contact ellipse between said tire and the ground. The slippage between the tire rubber and the metal of the service rim is substantial, resulting in degradation by resulting rapid wear of the portion of the bead referred to above and which is even greater since foreign bodies, such as grains of sand and dust may enter between the rubber and the metal.
From EP Application 0 168 754, tires are known in which the beads are provided with two bead rings, a main bead ring around which a radial carcass reinforcement can be anchored and an auxiliary bead ring around which a reinforcement ply can be wound. This is, of course, a tire for passenger cars intended to be mounted on a rim provided with a circumferential protrusion on the rim seat so as to counteract the unwedging of the bead. This type of tire generally does not present any damage at the level of the upturn of the carcass reinforcement or at the level of the ends of the reinforcement ply.
SUMMARY OF THE INVENTION
In order to remedy the above-indicated drawbacks, that is to say, in order to improve the resistance of the lower region of the tire to the degradation of the rubber forming it, as well as the resistance of the strengthening reinforcement to separation, a tire, in accordance with the invention, having a radial carcass reinforcement, a crown reinforcement and two beads, each reinforced by at least one bead ring around which the carcass reinforcement is wound and an auxiliary bead ring around which a ply of cords or cables is wound, is provided for use on a rim with seats inclined by an angle of 15.degree..+-.1.degree. with respect to the axis of rotation, having a nominal radius R.sub.N and circular rim flanges of radius .rho..sub.2 and of radius R.sub.J, with respect to the axis of rotation, these flanges being connected to the seats by circular portions of radius .rho..sub.1, is characterized by the fact that:
on the one hand, the base of each bead has, seen in meridian section, a profile comprising a generatrix of variable inclination with respect to the axis of rotation, the axially inner portion forming an angle of between 25.degree. and 30.degree. with respect to said axis and the axially outer portion
REFERENCES:
patent: 2501372 (1950-03-01), Benson
patent: 3111976 (1963-11-01), Delobelle
patent: 4061172 (1977-12-01), Yoshida et al.
patent: 4076066 (1978-02-01), Verdier
patent: 4345634 (1982-08-01), Giron
patent: 4365659 (1982-12-01), Yoshida et al.
patent: 4377193 (1983-03-01), Smith
patent: 4554960 (1985-11-01), Pompier
patent: 4700765 (1987-10-01), Masclaux
Ball Michael W.
Compagnie Generale des Etablissements Michelin - Michelin & Cie
Robey R.
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