Aircraft tire with carcass reinforcement including first and second families of carcass layers

Abstract

Aircraft tire comprises carcass reinforcement (5) comprising a first family of carcass layers extending between two beads (3), having at least one carcass layer wrapped, within each bead, from the inside towards the outside of the tire, around a bead wire (6) to form turn-up (511) having free end (E.sub.1) radially outside of radially outermost point (E) of the bead wire. The second family comprises at least two carcass layers, adjacent each to the next, extending, within each bead, from outside towards inside of the tire, as far as their respective ends (E.sub.2) which are radially inside of axial straight line (D.sub.Y) through centre (O) of bead wire (6) and axially inside of a radial straight line (D.sub.Z) through centre (O) at axial distance (d.sub.2) at least equal to 5 mm. The carcass layers of the second family are axially inside of at least one turn-up of a carcass layer of the first family.

Claims

1. An aeroplane tire, comprising: a tread connected by two side walls to two beads, which provide a mechanical connection between the tire and a rim; a crown reinforcement, radially on the inside of the tread, and a carcass reinforcement radially on the inside of the crown reinforcement; the carcass reinforcement comprising a first and a second family of carcass layers extending between the two beads; the first family comprising at least one carcass layer wrapped, within each said bead, from the inside towards the outside of the tire, around a circumferential reinforcing element known as a bead wire to form a turn-up having a free end radially on the outside of the radially outermost point of the bead wire; and the second family comprising at least two carcass layers, adjacent each to the next, extending, within each said bead, from the outside towards the inside of the tire, as far as their respective ends which are radially on the inside of an axial straight line passing through the centre of the bead wire and axially on the inside of a radial straight line passing through the centre of the bead wire at an axial distance at least equal to 5 mm, wherein the carcass layers of the second family are axially on the inside of at least one turn-up of a carcass layer of the first family, wherein each carcass layer comprises mutually parallel reinforcing elements, wherein the reinforcing elements of each carcass layer are made of textile materials, and wherein the textile reinforcing elements of each carcass layer being obtained by twisting, in the clockwise direction, at least two overtwists, each overtwist being obtained by twisting, in the anticlockwise direction, a spun fibre consisting of mutually parallel textile filaments, this twisting being defined by a number of turns per meter referred to as overtwisting, wherein the overtwisting, to obtain the overtwists of the textile reinforcing elements of the carcass layers, is at least equal to 250 turns/meter and at most 290 turns/meter.

2. The aeroplane tire according to claim 1, wherein the carcass layers of the second family are axially on the inside of all the turn-ups of the carcass layers of the first family.

3. The aeroplane tire according to claim 1, wherein the overtwists of the textile reinforcing elements of each carcass layer are made of aliphatic polyamide filaments.

4. The aeroplane tire according to claim 1, wherein the overtwists of the textile reinforcing elements of each carcass layer are made of aromatic polyamide filaments.

5. The aeroplane tire according to claim 1, wherein the overtwists of the textile reinforcing elements of each carcass layer consist of at least one overtwist made of aliphatic polyamide filaments and at least one overtwist made of aromatic polyamide filaments.

6. The aeroplane tire according to claim 1, which comprises an additional reinforcing layer wrapped around the bead wire and separating the bead wire from the carcass layers.

7. An aeroplane tire, comprising: a tread connected by two side walls to two beads, which provide a mechanical connection between the tire and a rim; a crown reinforcement, radially on the inside of the tread, and a carcass reinforcement radially on the inside of the crown reinforcement; the carcass reinforcement comprising a first and a second family of carcass layers extending between the two beads; the first family comprising at least one carcass layer wrapped, within each said bead, from the inside towards the outside of the tire, around a circumferential reinforcing element known as a bead wire to form a turn-up having a free end radially on the outside of the radially outermost point of the bead wire; and the second family comprising at least two carcass layers, adjacent each to the next, extending, within each said bead, from the outside towards the inside of the tire, as far as their respective ends which are radially on the inside of an axial straight line passing through the centre of the bead wire and axially on the inside of a radial straight line passing through the centre of the bead wire at an axial distance at least equal to 5 mm, wherein the carcass layers of the second family are axially on the inside of at least one turn-up of a carcass layer of the first family, wherein each carcass layer comprises mutually parallel reinforcing elements, wherein the reinforcing elements of each carcass layer are made of textile materials, and wherein the textile reinforcing elements of each carcass layer being obtained by twisting, in the clockwise direction, at least two overtwists, each overtwist being obtained by twisting, in the anticlockwise direction, a spun fibre consisting of mutually parallel textile filaments, this twisting being defined by a number of turns per meter referred to as overtwisting, wherein the overtwisting, to obtain the overtwists of the textile reinforcing elements of the carcass layers, of the second family is at least equal to 1.15 times the overtwisting, to obtain the overtwists of the textile reinforcing elements of the carcass layers of the first family.

8. The aeroplane tire according to claim 7, wherein the carcass layers of the second family are axially on the inside of all the turn-ups of the carcass layers of the first family.

9. The aeroplane tire according to claim 7, wherein the overtwists of the textile reinforcing elements of each carcass layer are made of aliphatic polyamide filaments.

10. The aeroplane tire according to claim 7, wherein the overtwists of the textile reinforcing elements of each carcass layer are made of aromatic polyamide filaments.

11. The aeroplane tire according to claim 7, wherein the overtwists of the textile reinforcing elements of each carcass layer consist of at least one overtwist made of aliphatic polyamide filaments and at least one overtwist made of aromatic polyamide filaments.

12. The aeroplane tire according to claim 7, which comprises an additional reinforcing layer wrapped around the bead wire and separating the bead wire from the carcass layers.

Description

BRIEF DESCRIPTION OF THE SINGLE DRAWING

(1) FIG. 1 shows a meridian cross section through a tire bead according to an embodiment of the invention.

(2) FIG. 1 has not been drawn to scale. Not all of the elements have necessarily been depicted. In particular, not all of the ends of the carcass layers have necessarily been referenced.

DETAILED DESCRIPTION OF THE SINGLE DRAWING

(3) FIG. 1 shows a meridian cross section of a tire 1 according to the invention, mounted on a mounted rim 4, in the side wall 2 and bead 3 region.

(4) The carcass reinforcement comprises a plurality of carcass layers distributed between a first family of carcass layers (51) and a second family of carcass layers (52).

(5) The first family consists of two carcass layers (51) wrapped, within each bead (3), from the inside towards the outside of the tire, around a bead wire (6) to form a turn-up (511) of which the end (E.sub.1) is radially on the outside of the radially outermost point (E) of the bead wire (6). The turn-up (511) is that portion of the carcass layer (51) that is comprised between the radially innermost point of the carcass layer, directly in line with the radially innermost point (I) of the bead wire (6), and the end (E.sub.1) of the turn-up (511). The carcass layers (51) of the first family are the carcass layers closest to the interior cavity of the tire and therefore axially innermost within the side wall (2).

(6) The second family consists of two carcass layers (52) extending, within each bead (3), from the outside towards the inside of the tire, as far as an end (E.sub.2) radially on the inside of the radially outermost point (E) of the bead wire (6). The carcass layers (52) of the second family are the carcass layers closest to the exterior surface of the tire and therefore axially outermost, within the side wall (2).

(7) The two carcass layers (52) of the second family are adjacent to one another and axially on the inside of all the turn-ups (511) of the carcass layers (51) of the first family. Moreover, the ends (E.sub.2) of the carcass layers (52) of the second family are radially on the inside of the axial straight line (D.sub.Y) passing through the centre (O) of the bead wire (6) and axially on the inside of the radial straight line (D.sub.Z) passing through the centre (O) of the bead wire (6).

(8) The invention has been studied more particularly for an aeroplane tire of radial carcass reinforcement and size 4617.0R20, used on an airliner, and the nominal pressure of which is 15.9 bar, the nominal load of which is 20642 daN and the maximum speed of which is 378 km/h.

(9) In the example studied, the carcass reinforcement comprises two carcass layers of the first family, two carcass layers of the second family and one additional reinforcing layer in contact with the bead wire. In the reference tire, representing the state of the art, the turn-ups of the layers of the first family are axially on the inside of the carcass layers of the second family. In the tire according to the invention, the turn-ups of the layers of the first family are axially on the outside of the carcass layers of the second family. The reinforcing elements of the carcass layers of the first and of the second family are identical and made of aliphatic polyamide or nylon.

(10) In the above configurations, numerical simulations by finite element calculation demonstrated that the maximum compression in the carcass layer of the second family which is axially outermost is equal to 1.6%, for the reference tire, and drops to practically zero for a tire according to the invention, hence demonstrating the hoped-for gain in bead endurance.