Pneumatic tire with annular member instead of bead wire
AssigneeCompagnie Generale des Etablissements Michelin - Michelin & Cie
InventorsMichel Ahouanto, Claude Eynard, Andre Peyrot
Life of this patent
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Abstract
Each bead of a pneumatic tire has the following characteristics: a) it has no bead wire and has an annular element whose tensile strength is ppreciably less than that necessary for a bead wire; b) at least two reinforcing plies are placed in contact with or near this annular element; c) the combination of reinforcing plies has a tensile strength at least equal to that which would be necessary for a bead wire; d) the carcass ply is wrapped around the annular element; e) the outer region of the bead includes a rubber having an elastic loss modulus G" of less than 1 MPa and/or it includes a rubber whose thickness is at most equal to 2 mm.
Claims15
A pneumatic tire which includes a crown, two beads and at least one carcass ply extending from one bead to the other, characterized in that each bead has the following features:
- a) it has no bead wire and includes an annular element whose tensile strength in the longitudinal direction is appreciably less than that which would be necessary for a bead wire in a known tire of the same size, the axis of this annular element being the axis of revolution of the tire;
- b) at least two adjacent plies called reinforcing plies are placed in contact with the annular element, or near this annular element;
- these reinforcing plies each include mutually parallel reinforcing cords, these cords being crossed from one ply to another;
- in each reinforcing ply, the angle .alpha. is the acute angle formed, at any point on a cord, by the direction of this cord and the tangent to a circle having as axis the axis of revolution of the tire and passing through this point on the cord, this angle .alpha. satisfying the relationship 0.degree.<.alpha..ltoreq.10.degree., the measurement being taken in a region where the reinforcing plies are practically oriented in mutually parallel planes;
- c) the combination of the reinforcing plies has a tensile strength, measured in the longitudinal direction, at least equal to that which would be necessary for a bead wire in a known tire of the same size;
- d) the at least one carcass ply is wrapped around the annular element;
- and
- e) that outer region of the bead which is intended to be placed on the side of a standard rim, at least in the area of the top of the rim flange, when the tire is fitted onto this rim, fulfills at least one of the following conditions:
- it is composed of a rubber which, in the vulcanized state, has an elastic loss modulus G" of less than 1, G" being expressed in MPa (megapascals), the measurement of G" being taken at a shear strain of 10%, at 50.degree. C. and at a frequency of 10 Hz;
- it is composed of a rubber whose thickness is at most equal to 2 mm.
Dependencies are inferred from the claim text.