Crown Reinforcement For An Airplane Tire

Abstract

Airplane tire comprises working reinforcement (2) radially inside of tread (3) and radially outside of carcass reinforcement (4). working reinforcement (2) comprises working biply (21). The radially innermost working biply (21) has the greatest axial width (L.sub.T) and comprises two axial ends (E). Carcass reinforcement (4) comprises carcass layer (41). Distance (D) between axial end (E) of the radially innermost working biply (21) and its orthogonal projection (I) onto the radially outermost carcass layer (41) is at least equal to 8 mm. Distance (D) between point (F) of radially innermost working biply (21), axially inside of axial end (E) at a distance (L) equal to 25 mm, and its orthogonal projection (J) onto the radially outermost carcass layer (41) is at most equal to the distance (D) and is such that angle (A) equal to atan[(DD)/L] is at least equal to 12.

Claims

1. An airplane 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 biply having two radially superposed working layers; each of said working layers comprising reinforcers coated in an elastomeric material, positioned circumferentially along a periodic curve and forming, with the circumferential direction of the tire and in the equatorial plane of the tire, an angle at least equal to 8 and at most equal to 30%; the radially innermost working biply having the greatest axial width (L.sub.T) and comprising two axial ends (E) each one corresponding to the axially outermost and radially innermost point of the working biply; the carcass reinforcement comprising at least one carcass layer comprising reinforcers which are coated in an elastomeric material, forming, with the circumferential direction of the tire, an angle at least equal to 80 and at most equal to 100; wherein the distance (D) between an axial end (E) of the radially innermost working biply and its orthogonal projection onto the radially outermost carcass layer is at least equal to 8 mm and wherein the distance (D) between the point (F) on the radially innermost working biply, axially on the inside of the axial end (E) at a distance (L) equal to 25 mm, and its orthogonal projection onto the radially outermost carcass layer is at most equal to the distance (D) between an axial end (E) of the radially innermost working biply and its orthogonal projection onto the radially outermost carcass layer and is such that an angle (A) equal to atan[(DD)/L] is at least equal to 12.

2. The airplane tire according to claim 1, wherein the distance (D) between the axial end (E) of the radially innermost working biply and its orthogonal projection onto the radially outermost carcass layer is at most equal to 16 mm.

3. The airplane tire according to claim 1, wherein the distance (D) between the point (F) on the radially innermost working biply, axially on the inside of the axial end (E) at a distance (L) equal to 25 mm, and its orthogonal projection onto the radially outermost carcass layer is such that the angle (A) equal to atan[(DD)/L] is at least equal to 15.

4. The airplane tire according to claim 1, wherein the distance (D) between the point (F) on the radially innermost working biply, axially on the inside of the axial end (E) at a distance (L) equal to 25 mm, and its orthogonal projection onto the radially outermost carcass layer is such that the angle (A) equal to atan[(DD)/L] is at most equal to 30.

5. The airplane tire according to claim 1, wherein the reinforcers of the working layers of any working biply are made of a textile material.

6. The airplane tire according to claim 1, wherein the reinforcers of the working layers of at least the radially innermost working biply are hybrid reinforcers made up of a combination of an aliphatic polyamide and an aromatic polyamide.

7. The airplane tire according to claim 1, wherein the tire comprises a hoop reinforcement comprising at least one hooping layer comprising reinforcers which are coated in an elastomeric material, forming, with the circumferential direction of the tire, an angle at most equal to 5, at least one hooping layer being radially on the inside of the radially innermost working biply and having an axial width (L.sub.F) at most equal to 0.8 times the axial width (L.sub.T) of the radially innermost working biply.

8. The airplane tire according to claim 1, wherein the tire comprises a protective reinforcement comprising at least one protective layer.

9. The airplane tire according to claim 8, wherein at least one protective layer comprises metal reinforcers coated in an elastomeric material.

Description

[0043] The features and other advantages of the invention will be better understood with the aid of the following FIGS. 1 to 5 which are not drawn to scale:

[0044] FIG. 1: A half-view in cross section of the crown of an aeroplane tire of the prior art, the section being in a radial plane (YZ) passing through the axis of rotation (YY) of the tire.

[0045] FIG. 2: A half-view in cross section of the crown of an aeroplane tire according to the invention, the section being in a radial plane (YZ) passing through the axis of rotation (YY) of the tire.

[0046] FIG. 3: A detailed view in cross section of the axial end of the working reinforcement of an aeroplane tire according to the invention, the section being in a radial plane (YZ) passing through the axis of rotation (YY) of the tire.

[0047] FIG. 4: A perspective view of a strip, that makes up a working biply of an aeroplane tire, circumferentially wound in a zigzag along a periodic curve on a cylindrical laying surface.

[0048] FIG. 5: A developed view of a strip that makes up a working biply of an aeroplane tire, wound circumferentially in a zigzag along a periodic curve after one period has been laid.

[0049] FIG. 1 depicts, in a radial plane YZ passing through the axis of rotation YY of the tire, a half-view in cross section of the crown of an aeroplane tire 1 according to the prior art, comprising a working reinforcement 2 radially on the inside of a tread 3 and radially on the outside of a carcass reinforcement 4. In the example given, the working reinforcement 2 comprises five working biplies 21, the radially innermost working biply having the greatest axial width L.sub.T, measured between its two axial ends. FIG. 1 shows only a half-width L.sub.T/2 between an axial end E of the radially innermost working biply 21 and the equatorial plane XZ. Each working biply 21 is made up at least in part of two radially superposed working layers (211, 212) (see FIG. 3). Each working layer (211, 212) comprises textile reinforcers of the aliphatic polyamide type, coated in an elastomeric material. The carcass reinforcement 4 comprises a superposition of carcass layers 41. Each carcass layer 41 comprises textile reinforcers of the aliphatic polyamide type, coated in an elastomeric material and forming, with the circumferential direction XX of the tire, an angle at least equal to 80 and at most equal to 100. Furthermore, radially on the inside of the tread 3, the tire 1 comprises a protective reinforcement 8 made up of a protective layer.

[0050] FIG. 2 shows, in a radial plane YZ passing through the axis of rotation YY of the tire, a half-view in cross section of the crown of an aeroplane tire 1 according to the invention, comprising a working reinforcement 2 radially on the inside of a tread 3 and radially on the outside of a carcass reinforcement 4. In the example given, the working reinforcement 2 comprises three working biplies 21, the radially innermost working biply having the greatest axial width L.sub.T, measured between its two axial ends E. FIG. 2 depicts only a half-width L.sub.T/2, between an axial end E of the radially innermost working biply 21 and the equatorial plane XZ. Each working biply 21 is made up at least in part of two radially superposed working layers (211, 212) (see FIG. 3). Each working layer (211, 212) comprises hybrid reinforcers made up of a combination of an aliphatic polyamide and of an aromatic polyamide. The carcass reinforcement 4 comprises a radial superposition of carcass layers 41. Each carcass layer 41 comprises hybrid reinforcers made up of a combination of an aliphatic polyamide and of an aromatic polyamide and forming, with the circumferential direction XX of the tire, an angle at least equal to 80 and at most equal to 100. Furthermore, the tire 1 comprises a hoop reinforcement 7 comprising a hooping layer comprising reinforcers coated in an elastomeric material forming, with the circumferential direction (XX) of the tire, an angle at most equal to 5. The hooping layer is radially on the inside of the radially innermost working biply 21 and has an axial width L.sub.F at most equal to 0.8 times the axial width L.sub.T of the radially innermost working biply 21. FIG. 2 depicts only an axial half-width L.sub.F/2 of the hooping layer. According to the invention, the geometric profile of the radially innermost working biply 21, at its axial end E, is not pressed as firmly against the carcass reinforcement as is the case in the tire of the prior art depicted in FIG. 1. Finally, radially on the inside of the tread 3, the tire 1 comprises a protective reinforcement 8 made up of a protective layer.

[0051] FIG. 3 is a detailed view in cross section of the axial end of the working reinforcement 2 of an aeroplane tire 1 according to the invention, in a radial plane YZ passing through the axis of rotation YY of the tire. In the example given, the working reinforcement 2 comprises three working biplies 21, the respective axial ends of which have overthicknesses. Each working biply 21 is made up of two radially superposed working layers (211, 212) in the main section and of three working layers in the axial end zone. Each working layer (211, 212) is made up of the axial juxtaposition of strips 9, each strip itself being an axial juxtaposition of textile reinforcers 5 coated in an elastomeric compound. In this instance, the textile reinforcers 5 are hybrid reinforcers made up of a combination of an aliphatic polyamide and of an aromatic polyamide. The carcass reinforcement 4 comprises a radial superposition of carcass layers 41, each carcass layer 41 comprising hybrid reinforcers made up of a combination of an aliphatic polyamide and of an aromatic polyamide and forming, with the circumferential direction XX of the tire, an angle at least equal to 80 and at most equal to 100. According to the invention, the distance D between an axial end E of the radially innermost working biply 21 and its orthogonal projection I onto the radially outermost carcass layer 41 is at least equal to 8 mm and the distance D between the point F of the radially innermost working biply 21, axially on the inside of the axial end E at a distance L equal to 25 mm, and its orthogonal projection J onto the radial outermost carcass layer 41 is at most equal to the distance D and is such that the angle A equal to atan[(DD)/L] is at least equal to 12. The angle A is the angle formed by the straight line passing through the axial end E of the radially innermost working biply 21 and through the point F of said biply, positioned 25 mm axially on the inside, and the straight line passing through their respective orthogonal projections I and J onto the radially outermost carcass layer 41.

[0052] FIG. 4 is a perspective view of a strip 9 that makes up a working biply of an aeroplane tire, circumferentially wound in a zigzag, along a periodic curve 6, onto a cylindrical laying surface 10 exhibiting symmetry of revolution about the axis of rotation (YY) of the tire, having a radius R.

[0053] FIG. 5 is a developed view of a strip 9 that makes up a working biply of a tire according to the invention, circumferentially wound in a zigzag, along a periodic curve 6, after one period has been laid. The strip 9 is laid on a cylindrical surface 10 of circumference 2R, depicted in developed form. The midline of the strip 9 follows a periodic curve 6, forming an angle B with the circumferential direction XX. The periodic curve 6 has a period P equal to 2R and an amplitude C which, increased by the width W of the strip 9, defines the width L.sub.T=C+W of the working biply.

[0054] The inventors carried out the invention for an aeroplane tire of size 46X17 R 20 the working reinforcement of which comprises 3 radially superposed working biplies. They compared a reference tire and a tire according to the invention, both having a working reinforcement comprising 3 radially superposed working biplies the reinforcers of which are hybrid reinforcers. The two tires, respectively the reference tire and the tire according to the invention, differ in terms of the geometric profile of the radially innermost working biply at its axial end, said profile being said to be pronounced in the case of the tire according to the invention.

[0055] The geometric characteristics of the tires under investigation are given in Table 1 below:

TABLE-US-00001 TABLE 1 Reference Invention Difference Distance D (mm) 5 mm 9 mm 4 mm Distance D (mm) 2 mm 2.5 mm 0.5 mm Distance L (mm) 25 mm 25 mm A = atan[(D-D)/L] () 6.8 12.4 5.6

[0056] The distances D, D and L are measured on a radial cross section of the tire.

[0057] The distance D is measured, at right angles to the radially outermost carcass layer, between the radially innermost point of the penultimate reinforcer of the radially innermost working biply and the radially outermost point of the first reinforcer encountered in the radially outermost carcass layer.

[0058] The distance D is measured, perpendicular to the radially outermost carcass layer, between the radially innermost point of the reinforcer of the radially innermost working biply, axially on the inside of the axially outermost reinforcer of the radially innermost working biply at a distance of 25 mm, and the radially outermost point of the first reinforcer encountered in the radially outermost carcass layer.

[0059] The distance L is measured as being the radius equal to 25 mm of the circle centred on the axially outermost reinforcer of the radially innermost working biply.

[0060] The respective performance of the tires of the prior art, considered by way of reference, and according to the invention, were measured against three criteria: the temperature in the vicinity of the axial end of the radially innermost working biply, the maximal tensile load in the reinforcers at the axial end of the radially innermost working biply over one revolution of the wheel, and the maximum number of cycles achieved without damage during a TSO test. The first two criteria came from a finite element numerical simulation on the assumption of steady-state running of the tire at a speed of 10 km/h. The number of cycles without damage were determined by TSO tests.

[0061] The performance criteria for the tires studied are given in Table 2 below:

TABLE-US-00002 TABLE 2 Reference Invention Difference Temperature at the axial end 93 C. 88 C. 5 C. under steady-state running at 10 km/h ( C.) Maximum tensile load at the axial 20 daN 18 daN 2 daN end, over one revolution of the wheel, in steady-state running at 10 km/h (daN) Number of cycles in TSO test base 100 103 3

[0062] This invention is applicable not only to an aeroplane tire but also to any tire comprising a crown reinforcement with at least one biply obtained by a zigzag winding of a strip such as, for example and nonexhaustively, a pneumatic tire for a metro train.