Aircraft Tire Crown Reinforcement

Abstract

Crown reinforcement of an aircraft tire with improved mechanical strength in order to increase the burst pressure of the tire, during a standard pressure test. An aircraft tire comprises a working reinforcement made up of a strip (5) wound continuously in a zigzag, from a starting end (51) to an ending end (52), in a circumferential direction (XX) of the tire, along a periodic curve (7) forming a non-zero angle A with the circumferential direction (XX) of the tire and in an equatorial plane (XZ) of the tire. The starting end (51) and the ending end (52) of the strip (5) are positioned axially at a distance (DI, DF) at most equal to 0.25 times the axial width W.sub.T of the working reinforcement from an axial end (E1, E2) of the working reinforcement.

Claims

1. Tire for an aircraft, comprising: a working reinforcement radially inside a tread and radially outside a carcass reinforcement; the working reinforcement being axially bounded by two axial ends, spaced apart by an axial width W.sub.T, and comprising at least two radially superposed working layers; each said working layer being comprised of a juxtaposition of portions of a strip of width W; and the strip being wound continuously in a zigzag, from a starting end to an ending end, in a circumferential direction of the tire, over a cylindrical surface having as its axis of revolution the axis of rotation of the tire, and along a periodic curve forming a non-zero angle A with the circumferential direction of the tire and in an equatorial plane of the tire, wherein the starting end and the ending end of the strip are positioned axially at a distance at most equal to 0.25 times the axial width W.sub.T of the working reinforcement from an axial end of the working reinforcement.

2. The aircraft tire according to claim 1, wherein the starting end and the ending end of the strip are positioned axially at a distance at most equal to 0.1 times the axial width W.sub.T of the working reinforcement from an axial end of the working reinforcement.

3. The aircraft tire according to claim 1, wherein the starting end and the ending end of the strip are positioned axially at a distance at least equal to 0.05 times the axial width W.sub.T of the working reinforcement from an axial end of the working reinforcement.

4. The aircraft tire according to claim 1, wherein the starting end and ending end of the strip are positioned axially from the same axial end of the working reinforcement.

5. The aircraft tire according to claim 1, wherein the starting end and ending end of the strip are positioned axially from two different axial ends of the working reinforcement.

6. The aircraft tire according to claim 1, wherein the starting end and ending end of the strip are positioned axially at an identical distance.

7. The aircraft tire according to claim 1, wherein the angle A formed by the periodic curve with the circumferential direction of the tire and in the equatorial plane of the tire is at least equal to 5.

8. The aircraft tire according to claim 1, wherein the angle A formed by the periodic curve with the circumferential direction of the tire and in the equatorial plane of the tire is at most equal to 20.

9. The aircraft tire according to claim 1, wherein the width W of the strip is at least equal to 2 mm.

10. The aircraft tire according to claim 1, wherein the width W of the strip is at most equal to 20 mm.

11. The aircraft tire according to claim 1, the strip being comprised of reinforcers coated in an elastomeric compound, wherein the strip comprises reinforcers comprised of a textile material.

12. The aircraft tire according to claim 1, the strip being comprised of reinforcers coated in an elastomeric compound, wherein the strip comprises reinforcers comprised of an aromatic polyamide.

13. The aircraft tire according to claim 1, the strip being comprised of reinforcers coated in an elastomeric compound, wherein the strip comprises hybrid reinforcers comprised of a combination of an aliphatic polyamide and an aromatic polyamide.

14. Method for manufacturing an aircraft tire according to claim 1, comprising a step of manufacturing the working reinforcement, wherein the strip is wound continuously in a zigzag, from a starting end to an ending end, 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 along a periodic curve corresponding to the mid-line of the strip and forming a non-zero angle A with the circumferential direction of the tire and in the equatorial plane of the tire, such that the starting end and the ending end of the strip are positioned axially at a distance at most equal to 0.25 times the axial width W.sub.T of the working reinforcement from an axial end of the working reinforcement.

15. The aircraft tire according to claim 1, wherein the width W of the strip is at least equal to 6 mm.

16. The aircraft tire according to claim 1, wherein the width W of the strip is at most equal to 14 mm.

17. The aircraft tire according to claim 1, the strip being comprised of reinforcers coated in an elastomeric compound, wherein the strip comprises reinforcers comprised of a textile material of an aliphatic polyamide.

Description

[0045] The features and other advantages of the invention will be better understood with the aid of the following FIGS. 1 to 5, which have not been drawn to scale:

[0046] FIG. 1: a half-view in section of an aircraft tire according to the invention, in a meridian or radial plane (YZ) passing through the axis of rotation (YY) of the tire.

[0047] FIG. 2: a perspective view of a strip circumferentially wound in a zigzag, along a periodic curve, over a cylindrical surface.

[0048] FIG. 3: a developed view of a strip circumferentially wound in a zigzag, with the starting end and ending end of the strip positioned in the equatorial plane of the tire, according to the prior art.

[0049] FIG. 4: a developed view of a strip circumferentially wound in a zigzag, with the starting end and ending end of the strip positioned on one and the same side of the equatorial plane of the tire, according to a first embodiment variant of the invention.

[0050] FIG. 5: a developed view of a strip circumferentially wound in a zigzag, with the starting end and ending end of the strip positioned on either side of the equatorial plane of the tire, according to a second embodiment variant of the invention.

[0051] FIG. 1 shows a half-view in section, in a radial plane (YZ), of a prior art aircraft tire 1, comprising a working reinforcement 2 radially inside a tread 3 and radially outside a carcass reinforcement 4. In the example shown, the working reinforcement 2 comprises a working bi-ply made up of two radially superposed working layers (21, 22) and obtained by circumferentially winding (see FIG. 2) a strip of width W in a zigzag over a cylindrical laying surface 6 of radius R, having as its axis of revolution the axis of rotation (YY) of the tire. The axial end overthicknesses of the working bi-ply 21 are not shown for the sake of simplicity. In a radial plane, each working layer (21, 22) is made up of an axial juxtaposition of strip portions 5 of width W/cos A, where W is the width of the strip 5, measured perpendicularly to its mid-line, and A is the angle (see FIG. 3) formed by the mid-line of the strip 5 with the circumferential direction (XX) in the equatorial plane (XZ). Since the width of the working reinforcement is equal to W.sub.T, its half-width W.sub.T/2 is shown in FIG. 1.

[0052] FIG. 2 is a perspective view of a strip 5 that makes up a working reinforcement of a prior art tire, wound circumferentially in a zigzag, along a periodic curve 7, over a cylindrical laying surface 6, which is rotationally symmetrical about the axis of rotation (YY) of the tire, having a radius R. Only three winding turns of the strip 5 are shown in FIG. 2, that is to say one working layer in the course of being produced.

[0053] FIG. 3 is a developed view showing the start and end of winding of a strip 5 having a width W in a zigzag, the mid-line 7 of said strip 5 forming an angle A with the circumferential direction XX and in the equatorial plane XZ, the intermediate part of the winding not being shown here. The amplitude of the zigzag defines the axial width W.sub.T of the working reinforcement, that is to say the axial distance between the two axial ends E1 and E2 of the working reinforcement. The prior art winding, shown in FIG. 3, is characterized by the strip starting end and ending end being positioned in the equatorial plane XZ, it being possible for this to be more generally in the vicinity of the equatorial plane XZ.

[0054] FIG. 4 is a developed view showing the start and end of winding of a strip 5 in a zigzag, according to a first embodiment variant of the invention. In this case, the starting end 51 and the ending end 52 of the strip 5 are positioned axially at respective distances DI and DF at most equal to 0.25 times the axial width W.sub.T of the working reinforcement from the same axial end E2 of the working reinforcement.

[0055] FIG. 5 is a developed view showing the start and end of winding of a strip 5 in a zigzag, according to a second embodiment variant of the invention. In this case, the starting end 51 is positioned at a distance DI at most equal to 0.25 times the axial width W.sub.T of the working reinforcement from the axial end E2 of the working reinforcement, and the ending end 52 is positioned at a distance DF at most equal to 0.25 times the axial width W.sub.T of the working reinforcement from the opposite axial end E1 of the working reinforcement.

[0056] The inventors produced an aircraft tire of size 50x20R22 according to the prior art and according to the second embodiment variant of the invention, respectively. The tire according to the second embodiment variant of the invention is characterized by the starting end and ending end of the strip being positioned axially on either side of the equatorial plane of the tire at axial distances with respect to the axial ends of the working reinforcement that are identical and equal to DI=DF=0.1 W.sub.T.

[0057] These tires were subjected to a pressure test using water according to standard TSO C62-e. The two tires burst as a result of their working reinforcement breaking. The burst pressure measured for the tire of the invention is 0.2 Pn greater than that measured for the prior art tire, Pn being the nominal inflation pressure of the tire.