Aircraft tire with specified zigzag working reinforcement
View Patent ↗The working reinforcement ( 2 ) of an aircraft tire is made by the zigzag winding of a strip ( 5 ) having width W, with a periodic curve ( 7 ), corresponding to the mid-line of the strip, forming, with the circumferential direction (XX), a non-zero angle A. The circumferential distance (c) between the extrema (S 51 , S 52 , S 53 ) of the respective mid-lines of two consecutive strip portions ( 51, 52, 53 ) is equal to the ratio W/sin A. For any set of three consecutive strip portions ( 51, 52, 53 ), made up of a first, a second and a third portion, the respective mid-lines of the first and third strip portions ( 51, 53 ) intersect at an intersection point (I), axially aligned with the extremum (S 52 ) of the mid-line of the second strip portion ( 52 ) and axially on the inside of said extremum (S 52 ) at an axial distance (a) at least equal to the width W.
1. An aircraft tire comprising:
a working reinforcement radially on the inside of a tread and radially on the outside of a carcass reinforcement;
the working reinforcement comprising at least one working bi-ply made at least in part of two radially superposed working layers;
each working layer being made up of a juxtaposition of portions of a strip of width W;
the strip being wound in a zigzag, in the circumferential direction of the tire, onto a cylindrical laying surface of radius R, having as its axis of revolution the axis of rotation of the tire, and with a periodic curve;
the periodic curve corresponding to the mid-line of the strip and forming, with the circumferential direction of the tire and in the equatorial plane of the tire, a non-zero angle A; and
two consecutive strip portions, each having respective mid-lines comprising extrema,
wherein the circumferential distance (c) between the extrema of the respective mid-lines of the two consecutive strip portions is equal to the ratio W/sin A between the width W of the strip and the sine of the angle A, and wherein, for any set of three consecutive strip portions, made up of a first, a second and a third portion having respective mid-lines comprising extrema, the respective mid-lines of the first and third strip portions intersect at an intersection point, axially aligned with the extremum of the mid-line of the second strip portion and axially on the inside of said extremum at an axial distance (a) at least equal to the width W of the strip, and
wherein any portion of the periodic curve, extending axially inwards from one extremum of the periodic curve to a point on the equatorial plane of the tire, comprises a first, concave circular portion of radius R 1 , extending axially inwards from the extremum to a second, convex circular portion of radius R 2 , the second, convex circular portion of radius R 2 extending axially inwards to a third, rectilinear portion forming an angle A with the circumferential direction, the third, rectilinear portion extending axially inwards to the point on the equatorial plane of the tire.
2. The aircraft tire according to claim 1 , wherein the intersection point between the respective mid-lines of the first and third strip portions is positioned axially on the inside of the extremum of the mid-line of the second strip portion at an axial distance (a) at most equal to twice the width W of the strip.
3. The aircraft tire according to claim 1 , wherein the intersection point between the respective mid-lines of the first and third strip portions is positioned axially on the inside of the extremum of the mid-line of the second strip portion at an axial distance (a) equal to R 1 *(1−cos B) with B=a sin((W/sin A)/R 1 ).
4. The aircraft tire according to claim 3 , wherein the ratio R 1 /W between the radius R 1 of the concave circular portion of the periodic curve and the width W of the strip is at least equal to 10.
5. The aircraft tire according to claim 1 , wherein the radius R 2 of the second, convex circular portion of the periodic curve is equal to the radius R 1 of the first, concave circular portion of the periodic curve.
6. A method for manufacturing an aircraft tire according to claim 1 , comprising a step of manufacturing the at least one working bi-ply and a step of manufacturing the aircraft tire such that the working reinforcement comprises the manufactured at least one working bi-ply.