Crown Reinforcement For Airplane Tire

Abstract

Aeroplane tire (1) comprises a working reinforcement (2) radially between tread (3) and carcass reinforcement (4). Working reinforcement (2) includes a working biply (21) comprised of the zigzag circumferential winding of strip (5) of width W onto a cylindrical laying surface (6) of radius R, with its axis of revolution being axis of rotation (YY) of the tire, in a periodic curve (7) with period P and forming angle A with circumferential direction (XX) of the tire in equatorial plane (XZ) of the tire. The winding of strip (5) comprises N periods P of curve (7) over T circumferences 2R of surface (6). N is a whole number which satisfies the following conditions: (a) N*(W/sin A)=2R, (b) N*P=2R*T, where T is a whole number, (c) N*T is the lowest common multiple of N and T,
and the ratio T/N is at least equal to 1.8 and at most equal to 2.2.

Claims

1. A tire for an aeroplane, 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 biply comprised of two radially superposed working layers; the at least one working biply comprised of a zigzag circumferential winding of a strip of width W onto a cylindrical laying surface of radius R, having as its axis of revolution the axis of rotation of the tire, in a periodic curve; the periodic curve having a period P and forming an angle A with the circumferential direction of the tire in the equatorial plane of the tire; the zigzag circumferential winding of the strip comprising N periods P of the periodic curve over a number T of circumferences 2R of the cylindrical laying surface; the number N of periods P of the periodic curve is a whole number which satisfies the following conditions: (a) N*(W/sin A)=2R, (b) N*P=2R*T, where T is a whole number, (c) N*T is the lowest common multiple of N and T, and the ratio T/N between the whole number T of circumferences 2R of the cylindrical laying surface and the whole number N of periods P of the periodic curve which are needed to make up the at least one working biply, is at least equal to 1.8 and at most equal to 2.2.

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

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

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

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

6. The aeroplane tire according to claim 1, the strip being made up of reinforcers coated in an elastomeric compound, wherein the strip comprises reinforcers made up of a combination of an aliphatic polyamide and of an aromatic polyamide.

7. A method of manufacturing an aeroplane tire according to claim 1, comprising a step of manufacturing the working biply, wherein the working biply is obtained by a zigzag circumferential winding of a strip of width W onto a cylindrical laying surface of radius R, having as its axis of revolution the axis of rotation of the tire, in a periodic curve, the periodic curve having a period P and forming an angle A with the circumferential direction of the tire in the equatorial plane of the tire, the zigzag circumferential winding of the strip comprising N periods P of the periodic curve over a number T of circumferences 2R of the cylindrical laying surface, the number N of periods P of the periodic curve being a whole number which satisfies the following conditions: (a) N*(W/sin A)=2R, (b) N*P=2R*T, where T is a whole number, (c) N*T is the lowest common multiple of N and T, and the ratio T/N between the whole number T of circumferences 2R of the cylindrical laying surface and the whole number N of periods P of the periodic curve which are needed to make up the working biply, being at least equal to 1.8 and at most equal to 2.2.

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

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

10. The aeroplane tire according to claim 1, the strip being comprised of reinforcers coated in an elastomeric compound, wherein the strip comprises reinforcers made of an aliphatic polyamide.

Description

[0037] The features and other advantages of the invention will be better understood with the aid of the following figures which have not been drawn to scale:

[0038] FIG. 1: a half view in cross section of an aeroplane tire according to the invention, in a radial plane (YZ) passing through the axis of rotation (YY) of the tire.

[0039] FIG. 2: a perspective view of a strip that makes up a working biply of a tire according to the invention, wound circumferentially in a zigzag in a periodic curve on a cylindrical laying surface.

[0040] FIG. 3: a developed view of a strip that makes up a working biply of a tire according to the invention, wound circumferentially in a zigzag in a periodic curve, after the laying of one period.

[0041] FIGS. 4A to 4D: developed views of a strip that makes up a working biply of a tire according to the invention, wound circumferentially in a zigzag in a periodic curve at various stages in the laying: after the laying of N=1 period (FIG. 4A), of N=4 periods (FIG. 4B), of N=8 periods (FIG. 4C) and of N=16 periods (FIG. 4D).

[0042] FIG. 1 depicts a half view in cross section, on a radial plane (YZ) passing through the axis of rotation (YY) of the tire, of an aeroplane tire 1 comprising a working reinforcement 2 radially on the inside of a tread 3 and radially on the outside of a carcass reinforcement 4. The working reinforcement 2 comprises a working biply 21, made up at least in part of two radially superposed working layers (211, 212) and obtained by the zigzag circumferential winding of a strip of width W onto a cylindrical laying surface of radius R having as its axis of revolution the axis of rotation (YY) of the tire. In a radial plane (YZ), each working layer (211, 212) is made up of an axial juxtaposition of portions of strip 5 of width W/cos A, where W is the width (not depicted) of the strip 5, measured perpendicular to the mean line of the strip 5, and A is the angle (not depicted) formed by the mean line of the strip 5 with respect to the circumferential direction (XX) in the equatorial plane (XZ).

[0043] FIG. 2 is a perspective view of a strip 5 that makes up a working biply of a tire according to the invention, wound circumferentially in a zigzag in a periodic curve 7 onto a cylindrical laying surface 6 of revolution about the axis of rotation (YY) of the tire, and of a radius R.

[0044] FIG. 3 is a developed view of a strip 5 that makes up a working biply of a tire according to the invention, wound circumferentially in a zigzag in a periodic curve 7 after the laying of one period. The strip 5 is laid on a cylindrical surface 6 of circumference 2R, depicted in developed form. The mean line of the strip 5 follows a periodic curve 7, forming an angle A with the circumferential direction (XX). The periodic curve 7 has a period P equal to 2R+B, where B is the portion of period P beyond the circumference 2R, and an amplitude C which, increased by two half-widths W/2 of the strip 5, namely by the width W of the strip 5, defines the width L=C+W of the working biply. The width of the strip 5, projected onto the circumferential direction (XX), is therefore equal to W/sin A.

[0045] FIGS. 4A to 4D depict developed views of a strip that makes up a working biply of a tire according to the invention, wound circumferentially in a zigzag, in a periodic curve, at various steps in the laying, respectively after the laying of N=1 period (FIG. 4A), of N=4 periods (FIG. 4B), of N=8 periods (FIG. 4C) and of N=16 periods (FIG. 4D). The example depicted corresponds to the creation of a working biply by zigzag circumferential winding of a strip, the winding comprising N=16 periods P of the periodic curve over a number T=21 circumferences 2R of the cylindrical laying surface of radius R. FIG. 4D depicts the developed view of the working biply fully formed, exhibiting a uniform appearance without gaps.

[0046] The inventors have carried out the invention for an aeroplane tire of size 1400X530 R 23 the working reinforcement of which comprises three superposed biplies, these respectively being radially inner, intermediate and radially outer, the geometric and laying characteristics of which are set out in Table 1 below:

TABLE-US-00001 TABLE 1 Working biply Radially inner Intermediate Radially outer biply biply biply Axial width L (mm) 370 mm 347.3 mm 321.5 mm Strip width W (mm) 11.4 mm 11.4 mm 11.4 mm Angle A () 5.1 4.8 4.5 Period P (mm) 8283 mm 8330 mm 8378 mm Laying radius R (mm) 649 mm 652 mm 655 mm Laying circumference 4076 mm 4095 mm 4113 mm 2R (mm) Number of periods N 32 30 28 Number of turns of 65 61 57 winding T Ratio T/N 2.03 2.03 2.03

[0047] In the tire under investigation, the inventors, seeking to obtain three working biplies radially superposed from the inside towards the outside, having respective axial widths substantially equal to 370 mm, 350 mm and 320 mm, and comprising hybrid textile reinforcers forming an angle of approximately 5 with the circumferential direction, created the said working biplies by zigzag circumferential winding of a strip of width 11.4 mm, in which the ratio between the number T of circumferences 2R of the cylindrical laying surface, or number of turns of winding, and the whole number N of periods P of the periodic curve needed to make up each working biply, is equal to 2.03, and therefore comprised between 1.8 and 2.2. The working biplies thus obtained meet the criterion of uniform thickness and therefore of uniform mechanical strength.

[0048] This invention is not restricted to the technical field of aeroplane tires but can also be applied to any tire comprising a crown reinforcement with at least one biply obtained by zigzag winding of a strip such as, for example and non-exhaustively, to a tire for a metro train. It can also be applied to a protective reinforcement where the latter comprises a biply obtained by zigzag winding of a strip.