EP1601541A1

EP1601541A1 - Mounted sets for a plane, wheels and tyres

Info

Publication number: EP1601541A1
Application number: EP04702316A
Authority: EP
Inventors: Christian Monnerie
Original assignee: Michelin Recherche et Technique SA Switzerland; Michelin Recherche et Technique SA France; Societe de Technologie Michelin SAS
Current assignee: Compagnie Generale des Etablissements Michelin SCA; Michelin Recherche et Technique SA France
Priority date: 2003-01-17
Filing date: 2004-01-15
Publication date: 2005-12-07
Also published as: EP2384910A2; BRPI0406773B1; US20090178749A1; US20050252593A1; BRPI0406773A; EP2384910A3; CA2512840A1; WO2004065141A1; US9027618B2; JP5106846B2; JP2006517164A

Abstract

The invention relates to mounted sets for a plane and wheels and tyres making up said sets. The mounted sets for a plane are characterised by a combined tyre pressure of more than 9 bars and a relative tyre crown of more than 30%. The wheel comprises a rim for receiving a tyre and more specifically seats receiving the beads of said tyre. According to the invention, the rim is provided with a hollow base functionality and is advantageously of the single-piece variety.

Description

MOUNTED ASSEMBLIES FOR AIRCRAFT, WHEELS AND TIRES

The invention relates to mounted assemblies for aircraft and the wheels and tires which constitute them. The assembled assemblies for aircraft concerned by the invention are characterized in particular by the combination of inflation pressure greater than 9 bars and a relative deflection of the tire greater than 30%.

The deflection of a tire is defined by the radial deformation of the tire, or variation of the radial height, when the latter passes from an unloaded state, to a static loaded state, under nominal load and pressure conditions. .

It is expressed in the form of a relative arrow, defined by the ratio of this variation in the radial height of the tire to half the difference between the outside diameter of the tire and the maximum diameter of the rim measured on the hook. The outside diameter of the tire is measured statically in an unloaded state at nominal pressure.

The reinforcement or reinforcement of tires and in particular aircraft tires is currently - and most often - consists of a ply or a stack of several plies conventionally designated “carcass plies”, “ summit tablecloths, etc. This way of designating the reinforcing reinforcements comes from the manufacturing process, consisting in producing a series of semi-finished products in the form of plies, provided with often longitudinal wire reinforcements, which are then assembled or stacked in order to make a blank of pneumatic. The sheets are made flat, with large dimensions, and are then cut according to the dimensions of a given product. The plies are also assembled, initially, substantially flat. The blank thus produced is then shaped to adopt the toroidal profile typical of tires. The semi-finished products called "finishing" are then applied to the blank, to obtain a product ready for vulcanization. Such a “conventional” type of process involves, in particular for the manufacturing phase of the tire blank, the use of an anchoring element (generally a bead wire), used to anchor or maintain carcass reinforcement in the tire bead area. Thus, for this type of process, a portion of each of the plies making up the carcass reinforcement (or only a part) is turned around a bead wire disposed in the bead of the tire. This creates an anchoring of the carcass reinforcement in the bead.

The generalization in the industry of this type of conventional process, in spite of numerous variants in the way of making the sheets and the assemblies, led the person skilled in the art to use a vocabulary modeled on the process; hence the terminology

. generally accepted, including in particular the terms "tablecloths", "carcass", "rod",

"Conformation" to designate the transition from a flat profile to a toroidal profile, etc.

Today there are tires which do not, strictly speaking, have "plies" or "rods" according to the preceding definitions. For example, document EP 0 582 196 describes tires produced without the aid of semi-finished products in the form of plies. For example, the reinforcing elements of the various reinforcing structures are applied directly to the adjacent layers of rubber mixtures, the whole being applied in successive layers to a toroidal core whose shape allows a profile to be obtained directly resembling the final profile. tire - during production. Thus, in this case, there are no more "semi-finished", nor "tablecloths", nor "rod". The basic products such as rubber mixes and reinforcing elements in the form of threads or filaments are applied directly to the core. This core being of toroidal shape, we no longer have to form the blank to pass from a flat profile to a profile in the form of a torus. Furthermore, the tires described in this document do not have the

"traditional" turning of the carcass ply around a rod. This type of anchoring is replaced by an arrangement in which there is disposed adjacent to said flank reinforcement structure of the circumferential wires, the whole being joined together by a rubbery mixture of anchoring or connecting. There are also methods of assembly on a toroidal core using semi-finished products, such as strips, specially adapted for rapid, efficient and simple installation on a central core. Finally, it is also possible to use a composite comprising both certain semi-finished products to produce certain architectural aspects (such as tablecloths, rods, etc.), while others are produced from direct application. mixtures and / or reinforcing element.

In this document, in order to take account of recent technological developments both in the field of manufacturing and for product design, the conventional terms such as "tablecloths", "rods", etc., are advantageously replaced by neutral terms or independent of the type of process used. Thus, the term “carcass-type reinforcement” or “sidewall reinforcement” is valid for designating the reinforcing elements of a carcass ply in the conventional process, and the corresponding reinforcing elements, generally applied at the sidewalls, d '' a tire produced using a semi-finished process. The term “anchoring zone” for its part, can designate just as much the "traditional" turning of the carcass ply around a rod of a conventional process, as the assembly formed by the circumferential reinforcing elements, the rubbery mixture and the adjacent flank reinforcement portions of a lower zone produced with a method with application to a toroidal core.

In what follows, the term "axial" means a direction parallel to the axis of rotation of the tire; this direction can be “axially interior” when it is directed towards the interior of the tire and “axially exterior” when it is directed towards the exterior of the tire.

“Radial” is understood to mean a direction perpendicular to the axis of rotation of the tire and passing through this axis of rotation. This direction can be “radially inside” or “radially outside” depending on whether it is directed towards the axis of rotation or towards the outside of the tire.

The term "a radially oriented reinforcing element" means a reinforcing element contained substantially in the same axial plane. The term “a circumferentially oriented reinforcing element” means a reinforcing element oriented substantially parallel to the circumferential direction of the tire, that is to say making an angle with this direction not deviating by more than five degrees from the circumferential direction. The term “reinforcing element” means both monofilaments and multifilaments, or assemblies such as cables, plies or any other equivalent type of assembly, whatever the material and the treatment of these reinforcing elements, for example surface treatment or coating or pre-gluing to promote adhesion to the rubber. The term "contact" between a reinforcing element and a rubber anchoring mixture means that at least part of the outer circumference of the reinforcing element is in intimate contact with the rubber anchoring mixture; if a reinforcing element comprises a coating or a coating, the term contact means that it is the outer circumference of this coating or of this coating which is in intimate contact with the rubbery anchoring mixture.

The term “modulus of elasticity” of a rubbery mixture is understood to mean a secant module of extension at 10% deformation and at room temperature; the measurement is carried out after a first accommodation cycle up to 10% deformation:

- E _w = - - ie E _l0 = - ^ - and E _lQ = - - - in which ε ₁₀ is equal to

OX? ₁₀ ύ _j) X “-. _[ g JJ XU. I 0.1; with Eio: secant extension module at 10% deformation; Fio: extension force at 10% extension; So: initial section of the test specimen; S: section of the test specimen at the extension deformation ε, in the case of rubber material, it is known that:

S S = - -; and εio: extension deformation at 10%. The elasticity modulus 1 + ε measurements of a rubbery mixture are carried out in tension according to the AFNOR-NFT standard.

46002 of September 1988: in second elongation (ie, after an accommodation cycle), the nominal secant module (or apparent stress, in MPa) is measured at 10% elongation (normal conditions of temperature and hygrometry according to standard AFNOR-NFT-40101 of December 1979).

The term “Tg” of an elastomer is understood to mean the glass transition temperature thereof measured by differential thermal analysis. “Static creep test” means a test in which test pieces are prepared, the useful part of which has a length of 70 mm, a width of 5 mm and a thickness of 2.5 mm (these test pieces are cut from vulcanized plates 2.5 mm thick); the test pieces are placed in an oven at 150 ° C. and a mass of 3 kg is immediately attached to them; the test is thus carried out with an initial constraint of:

σ _Q ≈ ^ - = 2.35MPa

with M: applied mass, g: acceleration of gravity and So initial section of the measuring cylinder; the elongation of the useful part of the test piece is measured as a function of time; the “static fogging rate” corresponds to the variation in deformation in a given time, for example between 3 and 5 hours of testing:

^{T ~} Δt with: Δε = ε (t ₂ ) - ε (tι) variation of the deformation measured during Δt = t ₂ - tj in minutes (mn).

The term “rheometry test” means an alternating shear test at a deformation of ± 0.2 degrees, a frequency of 100 cycles / min, a temperature of 197 ° C and a duration of 10 min; Monsanto rheometer; the test is carried out on a raw mixing disc, the evolution over the course of 10 min is recorded of the torque resulting from the shearing imposed between the two faces of the disc; the evolution of the torque after the measured maximum is particularly noted here; if the measured torque remains stable, there is no reversion, that is to say a reduction in the stiffness of the test piece, if the measured torque decreases, it is indicated that there is a reversion; the phenomenon of reversion reflects a reduction in the rigidity of the test piece under the conditions of the test; it is a test of the thermal stability of the mixture at high temperature; we notice :

_{r =} maχ - 10 _{χ l 0} Q max the rate of reversion at the end of the test; C _max is the maximum torque measured and Cio is the torque measured after 10 minutes of testing.

With regard to metallic wires or cables, the measurements of breaking strength (maximum load in N), breaking strength (in MPa) and elongation at break (total elongation in%) are carried out in tension according to ISO 6892 standard of 1984.

With regard to textile yarns or cables, the mechanical properties are measured on fibers which have been subjected to prior conditioning. "Pre-conditioning" means storing the fibers for at least 24 hours, before measurement, in a standard atmosphere according to the European standard DIN EN 20139 (temperature of 20 ± 2 ° C; humidity of 65 ± 2%). The mechanical properties in extension (toughness, modulus, elongation and energy at break) are measured in a known manner using a ZWICK GmbH & Co (Germany) type 1435 or type 1445 traction machine. The fibers, after having received a small preliminary protective twist (helix angle of approximately 6 °), undergo a traction over an initial length of 400 mm at a nominal speed of 200 mm / min. All results are an average of 10 measurements.

Tires can, as previously stated, adopt different types of construction.

US Patent 4,832,102 describes for example an airplane tire comprising a crown, two sidewalls and two beads, a carcass reinforcement and a crown reinforcement in which the carcass reinforcement comprises two circumferential alignments of reinforcements of high elasticity modulus , anchored in the two beads, and the crown reinforcement comprises at least one working block with at least one ply of reinforcements of high elasticity modulus. The carcass reinforcement is anchored in the beads by the inversion, around a rod, of the two circumferential alignments of first reinforcements of high elasticity modulus. Patent WO 02/00456 describes another type of tire for aircraft, the carcass reinforcement of which comprises two or three circumferential alignments of reinforcement elements of high elasticity modulus and anchoring means of said reinforcement elements, constituting the carcass reinforcement in each bead. The anchoring means according to this document consist of circumferentially oriented wires axially bordering the circumferential alignments of the reinforcement elements of the carcass reinforcement, said carcass reinforcement elements and the circumferentially oriented wires being separated by a mixture rubbery binding with very high modulus of elasticity. The use of wires makes it possible to obtain satisfactory rigidity with the smallest possible size of the bead; the compactness of the bead is essential for airplane tires in order to reduce the consequences of the heating of said beads.

Aircraft tires must withstand extreme conditions in service, in particular in terms of applied load and speed, given their low mass and size. As a result, despite their very high inflation pressures, greater than 9 bars, their crushing or deflection in service can commonly reach values twice that observed for heavy-duty or passenger car tires.

During take-off, very high speeds, of the order of 350 km / hour or even 450 km / hour, are reached, hence the very severe heating conditions.

All these conditions are particularly penalizing for the endurance of the beads of these tires.

These conditions are also binding as regards the holding of the tires on the rim. Until now, they have led to tires comprising an extremely rigid bead zone or zone of the bead which allows good grip on said rim. This rigidity of the low area of the tire consequently requires rims in several parts which allow the mounting and dismounting of aircraft tires.

Furthermore, the assembled assemblies thus produced for aircraft require strict, rigorous and frequent examinations. These checks may be accompanied by a dismantling of the assembled assembly and a dissociation of the wheel and the tire. These technical operations are long and require the intervention of a highly qualified workforce.

The object of the invention is in particular to provide a mounted assembly for an aircraft which facilitates these technical checks and more particularly which facilitates the disassembly and reassembly of the assembled assemblies during the life of an aircraft tire.

This object has been achieved according to one aspect of the invention by an assembly mounted for an aircraft consisting of a wheel and a tire comprising in particular beads, the inflation pressure of which is greater than 9 bars and whose relative deflection is greater at 30% o, said wheel comprising a rim for receiving the tire and more specifically seats receiving the beads of said tire, said rim comprising a hollow base functionality.

According to a preferred embodiment of the invention, the rim is of the monobloc type.

A hollow base functionality must be understood to mean that the wheel has a structure conferring a functionality comparable to that of a hollow base of a usual monobloc rim for applications other than those of the airplane; the function of a hollow base is in particular to authorize the fitting of a tire in combination with a certain deformation of the beads thereof. This mounting method is entirely conventional in applications other than those of the airplane. In these other applications, it is usual, for mounting a tire on a monobloc wheel, to provide in the part located between the seats of the wheel a recess area or hollow base which makes it possible to successively receive a part of each of the tire beads for mounting.

The beads of the tire of the assembly mounted according to the invention are advantageously ovalizable, that is to say deformable in their plane, preferably under industrially acceptable forces.

More preferably, the beads of the tire of the assembly mounted according to the invention can be warped, that is to say whose perimeter is deformable in the axial direction. The Applicant has found that, by acting on certain criteria, it is also possible to produce mounted assemblies for aircraft, the tires of which are suitable for mounting on a rim comprising a hollow base functionality.

It was thus unexpectedly obtained a mounted assembly for aircraft consisting of a tire and a wheel and more specifically a rim comprising a hollow base functionality advantageously of the monobloc type, without sacrificing in particular the endurance of the tire and the tightening of said tire on the rim. This achievement is particularly surprising if we are to remember that the technology of mounting tires on monobloc rims, classic in all categories of land vehicles for many years, has never been applied in the field of aircraft, despite the considerable extension of this mode of transport.

The assembly and disassembly of the assemblies mounted according to the invention can thus be carried out in a simpler and faster way than when it is a wheel made up of several parts. Indeed, the tools and skills required for these operations are simpler than according to the assemblies and disassembly usually practiced. This of course has economic benefits of various kinds with regard to. the direct means of implementation and the manpower and its necessary training.

In addition, the possibility of mounting an aircraft tire on a one-piece type wheel can make it possible to constitute an assembly assembled according to the invention, the mass of which is substantially less than the mass of a conventional assembly assembled, the wheel of which is made up of several parts. This can also lead to substantial economic advantages, the gain in mass of the assembled assembly being able to result in an increase in the transportable mass or in a reduction in the fuel consumption of the aircraft. The usual method of mounting a tubeless tire on a monobloc rim comprising a hollow base for applications other than aircraft applications consists of different steps which are as follows; we start by passing part of the first bead over the rim flange and we place this part in the hollow base. We can then pass the rest of the bead over the edge with a slight ovalization of the corresponding bead of the tire. The same is true for passing the second bead over the rim flange. The assembly is then terminated by a final step of inflation at a pressure such that it ensures the establishment of the beads on the seats bearing on the rim flanges. During this last step, the beads can cross humps which form an obstacle to the passage of said beads to their respective seats and then prevent the risks of stripping.

The invention provides that this hollow base functionality can be fulfilled for example by a limited recess area on the periphery of the wheel or even by one or more openings limited on the periphery of the wheel. In the latter embodiment, the invention advantageously provides that the braking system is integrated into the wheel by closing off the said opening or openings. This closure of the opening or openings can make it possible to play the role of anti-planing device; closing the opening (s) makes the hollow base functionality necessary for dismantling the tire or removing it disappear. Such a system can therefore possibly make it possible to have no humps.

Likewise, the invention provides that the openings ensuring the hollow base functionality can be closed by any means known to those skilled in the art as soon as they have fulfilled their function during mounting of the tire.

The invention also provides that the means ensuring the hollow base functionality can constitute a part of the braking device which is integrated inside the wheel.

According to an advantageous embodiment of the invention, the seats of the rim of the wheel of the mounted assembly have a slope of 5 °.

According to another embodiment of the invention, the seats of the rim of the wheel of the mounted assembly have a slope greater than 5 ° and preferably less than 15 °.

According to these latter embodiments of the invention, according to which the seats of the rim have a slope, the endurance of the beads of the tire can be improved. A first alternative embodiment of the invention advantageously provides that, the tire comprising a crown, two sidewalls and two beads, a carcass reinforcement anchored in the two beads and a crown reinforcement, in which the carcass reinforcement comprises at least a circumferential alignment of reinforcement elements and in which the means for anchoring said reinforcement elements in each bead comprise at least one reinforcement element oriented circumferentially, the carcass reinforcement of the tire comprises at least one layer of reinforcement elements having a turning area around at least one circumferentially oriented reinforcement element. According to this first alternative embodiment of the invention, the assembled assembly comprises an airplane tire in which the carcass reinforcement is anchored in the beads by turning around around at least one circumferentially oriented reinforcement element, such as a rod.

A second alternative embodiment of the invention advantageously provides that, the tire comprising a crown, two sidewalls and two beads, a carcass reinforcement anchored in the two beads and a crown reinforcement, in which the carcass reinforcement comprises at least a circumferential alignment of reinforcement elements and in which the means for anchoring said reinforcement elements in each bead comprise at least one circumferentially oriented reinforcement element, the means for anchoring said reinforcement elements in each bead of the tire comprise elements of circumferentially oriented reinforcement axially bordering said circumferential alignments of said reinforcing elements of the carcass reinforcement.

The invention also provides an aircraft wheel comprising a rim for receiving a tire, comprising in particular beads, and more specifically seats receiving the beads of said tire, the inflation pressure of the mounted assembly consisting of the wheel and said tire being greater than 9 bars and having a relative deflection greater than 30%, said rim comprising a hollow base functionality.

Preferably, the rim of the wheel according to the invention is of the one-piece type. As stated previously, according to a first embodiment of the invention, the seats of the wheel rim have a slope of 5 °.

According to another embodiment of the invention, the seats of the rim of the wheel have a slope greater than 5 ° and preferably less than 15 °.

The invention also proposes an aircraft tire, the inflation pressure of which is greater than 9 bars and whose relative deflection is greater than 30%, comprising a crown, two sidewalls and two beads, a carcass reinforcement anchored in the two beads and a crown reinforcement, in which the carcass reinforcement comprises at least one, and preferably at least two, circumferential alignments of reinforcement elements and in which the means for anchoring said reinforcement elements in each bead comprise at least one circumferentially oriented reinforcement element, the beads of the tire being ovalizable, that is to say deformable in their plane, preferably under industrially acceptable forces.

More preferably, the beads of the tire can be warped, that is to say of which the perimeter is deformable in the axial direction.

The invention also provides an aircraft tire, the inflation pressure of which is greater than 9 bars and whose relative deflection is greater than 30%, comprising a crown, two sidewalls and two beads, a carcass reinforcement anchored in the two beads and a crown reinforcement, in which the carcass reinforcement comprises at

20 at least one, and preferably at least two, circumferential alignments of reinforcing elements and in which the means for anchoring said reinforcing elements in each bead comprise at least one circumferentially oriented reinforcing element, and at least one rubbery mixture of anchoring in contact with the circumferential reinforcement and the reinforcing elements of the carcass reinforcement, the

25. rubbery mixture having a modulus of elasticity, at a deformation of 10%), less than 20 MPa.

The tire thus defined according to the invention has beads whose lower rigidity compared to the aircraft tires usually produced makes it easier to assemble and disassemble said aircraft tire. Surprisingly, the Applicant has found that this rubber anchoring mixture makes it possible, despite its rigidity much lower than what was previously recommended, to retain characteristics, particularly in endurance of the beads concerned, which are very satisfactory.

In a preferred embodiment _^ embodiment, the anchoring rubber mix comprises at least one synthetic elastomer included in the group of "SBR" or copolymer butabiène-styrene, and "BR", or polybutadienes with a total proportion of synthetic elastomer greater than 50% of the total mass of elastomers.

Preferably, the total proportion of synthetic elastomer is between 55 and 65% of the total mass of elastomers. Above 65%, the raw tack of the bonding gums becomes insufficient and this poses problems of making tire beads, on the other hand, below 55%>, the resistance of the rubber anchoring mixtures to a stress static fogging at high temperature degrades.

The rubbery anchoring mixture preferably comprises an SBR of Tg of between -70 ° and -25 ° C with a proportion by mass greater than 20%> of the total mass of elastomers.

It can also include a BR of Tg of between -110 ° and -90 ° C with a proportion by mass of less than 40% of the total mass of elastomers.

In fact, the presence of BR improves the thermal stability of the rubber anchoring mixture at high temperature, however, beyond 40% of the total mass of elastomers, the rubber anchoring mixture becomes difficult to produce.

According to an advantageous embodiment, the rubbery anchoring mixture withstands without breaking a static fogging stress at 150 ° C. under an initial stress of .2.35 MPa for at least 5 hours. Preferably, the rubbery anchoring mixture has a static fogging rate at

150 ° C under an initial stress of 2.35 MPa less than 2.10 ^"3 / min between 3 and 5 hours of stress. Preferably, said rubbery anchoring mixture has a rate of reversion after 10 min at 197 ° C of less than 10% and preferably less than 5%.

According to a first embodiment of the invention, it applies to an airplane tire in which the carcass reinforcement of the tire comprises at least one layer of reinforcing elements having a turning area around at least one circumferentially oriented reinforcement element, such as a rod.

According to this first embodiment, it appeared that the rubber mixture according to the invention makes it possible to confer, as previously stated, a certain flexibility on the bead which facilitates the mounting and dismounting of the tire. Advantageously also according to this first embodiment, when the carcass reinforcement is turned around a rod, the rubber mixture is advantageously present, in addition to the area between the rod and the carcass reinforcement, within the rod, between the various reinforcing elements constituting it. For certain types of tire, it can also advantageously be provided to subdivide the bead or bows to increase the proportion of rubber mixture according to the invention relative to the proportion of reinforcing element in a given zone. This can result in the presence of numerous subdivisions of rods arranged in an organized or unorganized manner. The rod (s) can be made up of wires or cables chosen from the group of carbon, tungsten, aramid, glass fiber or steel reinforcements.

According to a second embodiment of the invention, it applies to an aircraft tire in which the carcass reinforcement is anchored in the beads by means of circumferentially oriented reinforcing elements axially bordering said reinforcing elements of the carcass reinforcement. According to this second embodiment, in which the anchoring of the carcass reinforcement and the circumferential reinforcing elements is obtained by a rubber anchoring mixture, it has appeared that said rubber mixture according to the invention provides sufficient flexibility for improve the conditions for mounting and dismounting aircraft tires on their wheels. According to this second embodiment, the invention advantageously provides that the circumferential reinforcing elements are cables.

Preferably, said cables have an ability to penetrate between 80 and 100%), the breaking force of said cables being greater than 150 daN and said cables having an elongation at break greater than 4%.

The use of cables makes it possible to improve and facilitate the manufacture of the tires according to the invention according to manufacturing technologies of the type on toroidal core. The Applicant has found that the fact of replacing, in the tire according to the invention, an anchoring of the carcass reinforcement by means of circumferential wires coupled to the reinforcing elements of the carcass reinforcement by means of a rubber mix of anchoring, by anchoring by means of cables as defined above makes it possible to improve the yield of the manufacturing process. In addition, it appears that the use of the cables defined according to the invention makes it possible to maintain a compactness of the beads of the tire for satisfactory rigidity for the applications considered.

Indeed, it appears that the choice of cables having an aptitude for penetration as described authorizes a raw hooking of the cables in the zone of the bead in a satisfactory manner without risk of seeing the said cables detaching even partially during the manufacturing stages. of the subsequent tire which are produced before the curing of said tire.

In addition, the use of cables as circumferential reinforcing elements according to this second embodiment of the invention allows warping of the beads of the tire or deformation of the perimeter in the axial direction. Such a deformation further promotes the mounting and dismounting of aircraft tires according to the invention. Such deformation also allows, under very simple conditions, the mounting and dismounting of tires on one-piece rims, that is to say in a single part.

The use of a rod, according to the first embodiment of the invention, consisting of wires or cables, associated with a rubber mixture according to the invention present in the area between the bead wire and the carcass reinforcement and / or within the bead wire, between the various reinforcing elements constituting it, also allows the mounting and dismounting of tires on one-piece rims. However, such operations require greater efforts than in the case mentioned above according to the second embodiment of the invention.

The ability to penetrate according to the invention is the ability of the rubber to penetrate the free areas of a cable, that is to say the areas containing no material; it is expressed as a percentage of said free areas occupied by gum after cooking and determined by a test of air permeability. This air permeability test measures a relative index of air permeability. It constitutes a simple means of indirect measurement of the penetration rate of the cable by a rubber composition. It is carried out on cables extracted directly, by shelling, from the vulcanized rubber sheets which they reinforce, therefore penetrated by the cooked rubber. The test is carried out on a determined cable length (for example 2 cm) as follows: air is sent to the cable inlet, under a given pressure (for example 1 bar), and the quantity is measured air at the outlet, using a flow meter; during the measurement, the cable sample is locked in a tight seal so that only the quantity of air passing through the cable from one end to the other, along its longitudinal axis, is taken into account by the measurement. The measured flow rate is lower the higher the penetration rate of the cable by the rubber.

The elongation at break values according to the invention allow optimization of the working efficiency of the cables. In fact, according to the manufacturing techniques on a toroidal core, the cables are wound circumferentially to form several radially concentric or helical turns allowing better anchoring between the cables and the reinforcing elements of the carcass reinforcement. The elongation at break values of the cables according to the invention allow a deformation of said cables which leads to a greater efficiency of said turns. In other words, the deformation of said cables according to the invention makes it possible to obtain a more homogeneous, according to the winding length, of the stresses supported by the same winding of such a cable which does not have said elongation characteristics.

. Consequently, the combination of the elongation at break of the cables and their breaking force according to the invention makes it possible to maintain a compactness of the bead which is satisfactory for the applications targeted.

According to a preferred embodiment of the invention, the breaking force of the cables is less than 400 daN. A breaking force greater than such a value can lead, in particular in the case of an overall breaking force value of the fixed bead and of a diameter of imposed cables, to a reduction in the number of turns of said cables and therefore to a reduction in the anchoring height between the reinforcing elements of the carcass structure and the circumferentially oriented cables. Such a reduction in the anchoring height can be detrimental to the quality of said anchoring. Furthermore, if the increase in the breaking strength of the cables is combined with an increase in the diameter of said cables, this can cause problems of bulk, in particular in terms of widening of the lower zone.

More preferably, the elongation at break of the cables is less than 8%. A higher elongation could lead to tires whose stiffness of the beads, for high pressures, is not sufficient to guarantee the holding of said tire on a rim and to guarantee the transmission of braking torques. The elongation at break values of the cables according to the invention are advantageously obtained by heat treatments of cables qualified as "large elongation" treatment. Such treatments known to those skilled in the art are for example described in European patent EP 0 751 015.

According to an advantageous embodiment of the invention, the cables according to the invention comprise a conventional adhesive coating such as a brass coating so as to improve the adhesion between said cables and the rubber mixtures.

The circumferentially oriented cables preferably have an extension module greater than that of the reinforcing elements of the carcass reinforcement. They are preferably chosen from the group of carbon, tungsten, aramid, fiberglass or steel reinforcements.

According to another characteristic of the tire according to the invention, by considering

ΣRi sum of the rigidities of extension of the circumferentially oriented cables arranged axially internally relative to the carcass reinforcement and considering ΣR _E sum of the stiffnesses of extension of the circumferentially oriented cables arranged axially on either side of the carcass reinforcement , we have :

TR 0.6 ≤ ^ - ≤ 1.5

∑_ ^K ε and preferably:

Compliance with these limits for the ratio between the total extension rigidity of the circumferentially oriented cables arranged inside the carcass reinforcement in each bead and the total extension rigidity of the circumferentially oriented cables disposed outside of the carcass reinforcement has the advantage of making the stress of the cables oriented circumferentially in the bead more homogeneous, whatever their position.

According to a preferred embodiment of the invention, the external surface of the bead of the tire according to the invention comprising a seat followed by a frustoconical wall of substantially radial orientation adjacent radially internally to a wall of cross section substantially in an arc of a circle and of center C disposed externally relative to the bead, these walls being intended to bear against the hook and the rim of a suitable rim, considering a line CD, crossing the bead of the tire at an angle α = + 45 ± 5 degrees relative to the axis A of the tire, all of the circumferentially oriented cables are disposed at a radial distance from the axis of the tire less than or equal to this line CD. This line CD substantially defines a very rigid embedding zone, where the deformations are very reduced and a bending zone radially above CD. The fact that all the circumferentially oriented cables are in the embedding area increases the endurance of the bead.

Preferably, the bead of the tire according to the invention having an outer surface intended to come into contact with the corresponding surface of the seat and of the rim hook, after mounting on said rim and inflation of the tire, the contact zone between the surface outside of the bead and the rim extends at least to point B of the hook of maximum radius Rj.

Advantageously, Φ being the diameter of the circumference of the outer surface of the bead intended to come to bear against the circumference of the hook of the rim of maximum radius Rj, we have:

= 2 (Λ, - *) with ε between 0.5 and 2 mm.

This allows the bead to properly “sit” on the seat and the rim hook and has the advantage of limiting the curvature taken by the circumferential alignments of the carcass reinforcement during rolling, particularly in the area of contact.

According to the invention, the reinforcing elements constituting the carcass reinforcement can be any type of reinforcing elements in wire form, capable of reinforcing a determined matrix, for example a rubber matrix. By way of reinforcing elements, mention may be made, for example, of multifilament fibers (“multifilament yarns”), these fibers being able to be twisted or not on themselves, individual threads such as cylindrical or oblong monofilaments, with or without twisting themselves, cords or twists ("cords") obtained by wiring or twisting operations of these unitary threads or of these fibers, such reinforcing elements being able to be hybrid, that is to say composite, comprising elements of different natures.

“Plied yarn” or “folded yarn” is understood to mean a reinforcing element constituted by two strands (“single yarns”) or more assembled together by twisting operations; these strands, generally formed of multifilament fibers, are first individually twisted in one direction (direction of torsion S or Z) during of a first twisting step, then twisted together in the opposite direction (direction of twist Z or S, respectively) during a second twisting step.

According to an advantageous embodiment of the invention, the reinforcing elements constituting the carcass reinforcement are, for example, made of aromatic polyamide or reinforcing elements such as those described in patent application WO 02/085646. It can be wires or cables.

Advantageously also, the carcass reinforcement of the tires according to the invention comprises two or three circumferential alignments of reinforcing elements for example. Advantageously, more specifically with regard to tires produced on a hard core, each circumferential alignment of the carcass reinforcement is, in each bead, bordered axially internally and axially externally by cables oriented circumferentially.

According to an advantageous embodiment, concerning even more specifically the tires produced on a hard core, the reinforcing elements of the carcass reinforcement form back and forth arrangements arranged adjacent, with, at the level of each bead, loops connecting each times a go to a return.

In variant embodiments of the invention, the crown reinforcement of the aircraft tire according to the invention preferably comprises at least one working block with one or more layers of parallel reinforcing elements in each layer, oriented substantially circumferentially ; it is advantageously reinforcing elements consisting of aromatic polyamide, or reinforcing elements such as those described in patent application WO 02/085646.

If necessary, the crown reinforcement comprising a central zone and two lateral zones, the working block further comprises at least two layers of reinforcing elements, oriented substantially circumferentially, arranged axially on either side of the median plane of the pneumatic in the lateral zones of said apex. These layers make it possible to withstand the forces due to centrifugation at high speed. They are preferably arranged radially internally relative to the two layers of elements. circumferentially oriented reinforcement of the working block. These two reinforcing layers have the advantage of increasing the hooping of the lateral zones of the crown without increasing its thickness.

The crown reinforcement may also further comprise at least two layers of reinforcing elements, mutually parallel in each layer and crossed from one layer to the next, making with the circumferential direction an angle α, between 5 ° and 35 ° to reinforce the rigidity of the tire drift. The reinforcing elements are, for example, reinforcing elements such as those described in patent application WO 02/085646. The crown reinforcement may also include, disposed radially outward relative to the working block, a protective crown layer. This protective layer preferably extends axially beyond the axial width of the layers of reinforcement elements of circumferential orientation.

As stated above, the aircraft tire according to the invention is particularly advantageous for constituting an assembly mounted with a one-piece type wheel. Indeed, the possible deformation of the beads of the tire makes it possible in particular to mount and dismount the tire on such a wheel. In addition, these assembly and disassembly can be carried out in a simpler and faster way than when it is a wheel made up of several parts. This has economic advantages of various kinds, in particular with regard to the direct means of implementation and the manpower and its necessary training as mentioned above.

The invention thus proposes the use of a tire as it has just been described in an assembly mounted for an aircraft as described above, the rim of which is of the one-piece type comprising a hollow base functionality.

The invention also proposes the use of a tire in a mounted assembly for an aircraft as described above, the wheel of which is of the monobloc type comprising a hollow base functionality, said tire comprising at least one any of the characteristics of the tire according to the invention as described above.

The invention also proposes a use of a tire as it has just been described in a mounted assembly for an airplane whose inflation pressure is greater than 9 bars and whose relative deflection is greater than 30%, consisting of a wheel and the tire, said wheel comprising a rim for receiving the tire and more specifically seats receiving the beads of said tire, said wheel being of the multi-part type.

The invention also proposes the use of a tire in a mounted assembly for an airplane whose inflation pressure is greater than 9 bars and whose relative deflection is greater than 30%, consisting of a wheel and the tire, said wheel comprising a rim for receiving the tire and more specifically seats receiving the beads of said tire, said wheel being of the multi-part type, said tire comprising at least any one of the characteristics of the tire according to the invention as described above.

The invention also provides an assembled assembly for an airplane, the inflation pressure of which is greater than 9. bars and the relative deflection of which is greater than 30%), consisting of a wheel and a tire as described above, comprising in particular beads, said wheel comprising a rim for receiving the tire and more specifically seats receiving the beads of said tire, said wheel being of the multi-part type.

The tire according to the invention also has advantages with regard to the mounting and dismounting of the assembly assembled in the case of a wheel in several parts. In fact, the flexibility of the beads of the aircraft tire according to the invention will make it possible to facilitate the positioning of the tire during mounting by reducing the risks of degradation of the latter.

Furthermore, the tire according to the invention makes it possible to facilitate the dismantling operations of such mounted assemblies. The extreme conditions of use of these mounted assemblies lead to a very strong connection between the tire and the rim which requires exerting on said tire significant forces; these must be exerted very homogeneously on the periphery of the sidewall of the tire when the latter has rigid beads at the risk of blocking the assembled assembly as soon as the bead is positioned at an angle relative to the rim of the wheel. In the case of the invention, this operation is simplified due to the flexibility of the beads of the tire. The tools and the qualification of the workforce may thus be less specialized in the case of the invention.

Other details and advantageous characteristics of the invention will emerge below from the description of examples of embodiments of the invention with reference to FIGS. 1 to 7 which represent:

FIG. 1, a schematic view in axial section of a tire according to the invention,

- Figure 2, a schematic representation of a sectional view of a cable according to the invention, - Figure 3, a schematic perspective view showing the arrangement of part of the reinforcements of the carcass reinforcement,

FIG. 4, a schematic representation of a bead according to a second embodiment of the invention,

FIG. 5, a schematic view in axial section of a tire according to an alternative embodiment of the invention shown in FIG. 1,

FIG. 6, a schematic view in axial section of a tire according to another alternative embodiment of the invention shown in FIG. 1,

- Figure 7a, 7b, 7c, the steps of mounting a tire on a rim to form an assembly mounted according to the invention. Figures 1 to 7 are not shown to scale to simplify understanding.

The airplane tire 1 shown diagrammatically in axial half-section in FIG. 1 comprises a crown 2, two sidewalls 3 and two beads 4. A carcass reinforcement 5 extends from one bead 4 to the other and is formed of two circumferential alignments 6 and 7 of reinforcing elements. The circumferential alignments of reinforcing elements 6 and 7 are oriented radially in the sidewalls 3 and consist of reinforcing elements made of aromatic or ara ide polyamide. The reinforcing elements are arranged in parallel and are separated by a mixture layer 8, the nature and module of which are adapted as a function of their position in the tire. The two circumferential alignments 6 and 7 are anchored in the beads

3 by alignments or “stacks” 9 of circumferentially oriented wound cables and axially arranged on either side of each circumferential alignment of the reinforcing elements 6 and 7. Each alignment or stack 9 of circumferentially oriented cables can be obtained by helical winding a cable. The radial reinforcing elements of the carcass reinforcement and the circumferentially oriented cables are separated from each other by a rubbery mixture of binding or anchoring 10 to avoid direct contact of one reinforcing element with another. This rubbery anchoring mixture according to the invention has a rigidity such that its extension module at 10%> deformation is between 10 and 20 MPa. The rubber anchoring mixture according to the invention has, as other mechanical characteristics, excellent resistance to creep at high temperature and very good stability at high temperature. The rigidity chosen gives the bead structures described sufficient flexibility to allow easy mounting and dismounting of the tires, without degrading endurance performance; the resistance to creep is essential to obtain a solid and durable anchoring of the carcass reinforcements in the beads and the thermal stability at high temperature is also important because of the very severe thermal conditions which the tires can undergo in service.

The tension which develops in the radial reinforcing elements during inflation of the tire 1 is taken up in particular by the lateral adhesion between each circumferential alignment 6 and 7 and the stacks 9 of cables circumferentially oriented. This bead structure provides excellent anchoring which remains very effective even for the very high inflation pressures of aircraft tires, greater than 9 bars and which can reach 25 bars in certain particular applications. The tires have shown an ability to withstand four times the operating pressure as required by TSO C62. The stacks 9 of circumferentially oriented cables are divided into three groups, two stacks 11 arranged axially outside the carcass reinforcement 5 on the outside of the tire, two stacks 13 arranged axially internally relative to the carcass reinforcement 5, on the inside of the tire and 4 piles 12 arranged between the two circumferential alignments 6 and 7 of the carcass reinforcement 5.

The invention may also provide for the placement of cones of rubber mixes axially between the carcass reinforcement and the stacks 9 of circumferentially oriented cables to allow the placement of circumferentially oriented cables such that the axial distance between them and the carcass reinforcement ^' increases in the radial direction. This variant embodiment is not illustrated in the figures. Such placement of the cables has been described in French application FR 0209355.

In the case of the tire described, considering the number of turns arranged internally and externally relative to the carcass reinforcement, we obtain:

ΣRI / ΣRE ≤. 1.24.

This has the advantage of homogenizing the mechanical stress of the cables oriented circumferentially in the bead.

It can also be noted that the number of turns of the batteries decreases progressively with the distance relative to the axis of rotation A of the tire 1. This results in a substantially conical shape in the arrangement of the cables oriented circumferentially. This has the advantage of strongly stabilizing the beads 4 during inflation of the tire and when passing through the contact area in service.

All the turns of the batteries 9 are embedded in the rubbery mixture 10 of extension module with 10% deformation of between 10 and 20 MPa to ensure good recovery of the forces due to the inflation pressure and thus an excellent anchoring of the carcass reinforcement in the beads 4.

FIG. 2 illustrates a cable 80 used, according to the invention, in circumferential winding as a means of anchoring the reinforcing elements of the carcass reinforcement. Cable 80 is a layered cable of formula 9.35, i.e. consisting of 9 elementary wires of diameter equal to 35/100 mm; the cable 80 corresponds to the formula 2 + 7 with 2 wires 81, constituting the first layer, twisted together to form a plied, and 7 wires 82, forming the outer layer, wound together in a helix around the first layer. FIG. 2 illustrates this winding by representing the 7 wires 82 in contact with the circle 83 diagramming the space occupied by the plied formed by the 2 wires 81 of the first layer. The wires 81, 82 are made of steel with a carbon content of between 0.7 and 0.9%). The wires have been previously treated to have a brass coating promoting the adhesion of the wire to the rubber. The wires have a work hardening rate of less than 3.5. The cable has a total diameter D ′, corresponding to the diameter of the circumscribed circle 84 at the outer layer, equal to 1.35 mm. The measurement of the penetration ability of this cable made according to the method described above resulted in a value of 100%. The cable breaking force is 198 daN and its elongation at break is 5.4%. The elongation at break is obtained after a heat treatment such as that mentioned above; the heat treatment makes it possible to increase the elastic and plastic elongations which are added to the structural elongation. The latter is equal to 0.1% o for cable 80 of formula 9.35.

Another layered cable, of formula 13.35, was tested; this cable is made up of 13 elementary wires of diameter equal to 35/100 mm and of formula 4 + 9, with 4 wires, constituting the first layer, twisted together to form a plied, and 9 wires, forming the outer layer, wound together helically around the first layer. The elementary wires are the same as in the previous case. The measurement of the penetration ability of this cable made according to the method described above. led to a value of 80%>. The breaking force of the cable is equal to 282 daN and its elongation at break of 6.4%. Note that the structural elongation of this cable of formula 13.35 is 0.2%.

Figure 3 is a perspective view of one of the circumferential alignments of the reinforcing elements, alignment 6, in which only the reinforcing elements are shown. In this FIG. 3, we can see the circumferential alignment 6 of the reinforcing elements of the carcass reinforcement which is made up of portions of reinforcing elements 17. At their radially lower ends, the portions of reinforcing elements 17 form juxtaposed loops 18 located in the bead 4. These loops 18 are adjacent and do not overlap. On both sides axially of the circumferential alignment 6 of the reinforcing elements of the carcass reinforcement, only the stacks 11 and 12 are shown, of circumferentially oriented reinforcing elements, directly adjacent to this alignment 6. For the clarity of the drawing, only the alignment circumferential ^" 6 of reinforcing elements and two stacks have been shown, but, the circumferential alignment 7 of reinforcing elements of the carcass reinforcement has the same arrangement of the reinforcing portions 17.

FIG. 4 illustrates a bead 21 and a sidewall 22 of a second embodiment of a tire 20 according to the invention in which the carcass reinforcement 23 consists of two circumferential alignments, 24, 25 of reinforcing elements in aromatic or aramid polyamide. In the bead 21 are disposed stacks 27 of cables of circumferential orientation. These stacks 27 are here separated into three groups. There are successively axially from the inside of the bead towards the outside, two stacks 28 arranged internally relative to the circumferential alignment of reinforcing elements of the carcass reinforcement 24, three stacks 29 disposed between the circumferential alignments of reinforcement of the carcass reinforcement 24 and 25, and two stacks 30 arranged externally relative to the circumferential alignment of reinforcing elements of the carcass reinforcement 25.

As before, the number of turns of circumferentially oriented cables is such that it is verified that the sum of the extension rigidities of the stacks arranged externally relative to the carcass reinforcement is substantially of the same order as the sum of the extension rigidities stacks arranged internally relative to the carcass reinforcement 23.

The outer surface of the bead 21 comprises a seat 32, a frustoconical wall of substantially radial orientation 33 adjacent radially internally to a wall 34 whose section is an arc of a circle EF with center C. C is disposed outside of the bead 21 Considering the line CD which crosses the bead at an angle Ω: = +45 + 5 degrees relative to the axis of rotation A of the tire (this angle is determined when the tire is mounted on its rim), it can be seen that all of the circumferentially oriented reinforcing elements 27 are disposed at a radial distance from the axis A less than or equal to this line CD. This CD line substantially defines an area very rigid installation where the deformations are very reduced and a bending zone radially above CD. The fact that all the circumferentially oriented reinforcing elements are in the embedding zone increases the endurance of the bead. This outer surface of the bead is intended to come to bear against the wall of a rim 35, the outer profile of which is also shown in FIG. 4. This profile comprises the seat 36 and the substantially radial wall of the hook 37 followed by the rim 38 The rim 38 has a cross section in an arc of a circle with a center C. The point of greatest diameter is B, of radius Rj. The point E disposed on the axially outer surface of the bead 21 is intended to come into contact with substantially the point B. When the tire is mounted on the rim 35, the surfaces 34 and 38 are homocentric, that is to say that their centers C and C are combined. The point E is arranged on a circumference of diameter Φ. We have the relation:

Φ = 2 (R _j - ε) with ε between 0.5 and 2 mm.

This slight offset from point E between its free position and its position mounted on the rim, in contact with B, allows the bead to be slightly extended during its mounting on the rim and promotes the quality of the contact obtained. This contact up to point E reinforces the stability of the bead when the tire is pressurized and when it passes through the contact area in service. Consequently, it can be seen that the circumferential alignments of the carcass reinforcement are much less stressed in compression when passing through the contact area, unlike what happens for aircraft tires of conventional architecture.

Also shown in FIG. 1 is a first example of crown reinforcement 14. This consists of a working block comprising two layers of reinforcing elements 15 and 16 of substantially circumferential orientation obtained by helical winding of at least one reinforcing element. The number of reinforcing layers as well as the laying pitch are adapted according to the size of the tire and its conditions of use. This embodiment of a crown reinforcement has the advantage of providing a very effective hooping which minimizes the variation of the dimensions of the tire during inflation as well as at high speed. It can be seen that the evolution of the profile can be three to four times lower than for a common aircraft tire such as an AIRX 30x8.8R15. This excellent hooping also has the advantage of not greatly expanding the mixtures constituting the tread of the top of the tire. Cracks on the surface of the tread due to ozone in the air are greatly reduced.

The crown reinforcement 41 of the tire 40 presented in FIG. 5 comprises, as before, two layers of reinforcement elements of substantially circumferential orientation 15 and 16 and is completed by two layers 42 and 43 of reinforcement elements, oriented substantially circumferentially arranged axially on either side of the median plane of the tire in the lateral zones of the crown. They make it possible to reinforce the hooping of the lateral zones L of the top. The layers 42 and 43 are arranged radially between the layers 15 and 16 and the carcass reinforcement 5.

The frame 41 is also completed by a protective top layer 44 disposed radially outwardly relative to the other layers of the top frame 41. This protective top layer may be made up of corrugated metal reinforcing elements so as not to be stressed in normal running. It should be noted that this protective layer extends axially beyond the layers 15 and 16 on either side of the median plane P of the tire by an axial distance a.

FIG. 6 shows a tire 50 with a crown reinforcement 51 additionally comprising two layers 52, 53 of reinforcing elements, mutually parallel in each layer and crossed from one layer to the next, making an angle with the circumferential direction α, between 5 ° and 35 °. These two layers are arranged radially below the layers of circumferential reinforcing elements 15 and 16. They increase the drift thrust of the tire 30 relative to that of the tire 40. FIGS. 7a, 7b, 7c illustrate by sectional diagrams the steps for mounting a tire according to the invention on a wheel 72 of the one-piece type comprising a hollow base functionality represented by the recesses 73. The figures schematically represent only the beads 70, 71 of the tire according to the invention. In FIG. 7a, it can be seen that part of the first bead 70 has passed over the rim 74 and is now placed in the recess or hollow base 73. It is then possible to pass the rest of the bead 70 through- above the rim 74 thanks to a slight ovalization of the corresponding bead of the tire. The necessary deformation of the bead 70 to perform this step must make it possible to obtain a diametrically opposite edge-to-edge distance from the bead 70 equivalent to the length N. This deformation of the bead is also accompanied by warping of the bead 70 making it possible to make pass the bead 70 over the rim 74 of the rim gradually. The diameter of the bead 70 corresponds substantially to the diameter W of the rim seat which is to receive the bead. FIG. 7b shows that it is the same for passing the second bead 71 over the rim 74 of the rim 72. Part of the second bead 71 is passed over the rim 74 and is now placed in the area in recess or hollow base 73. As previously for the bead 70, it is then possible to pass the rest of the bead 71 over the rim 74 by slightly ovalizing the corresponding bead of the tire, accompanied by warping of this one.

FIG. 7c illustrates the end of the assembly by an inflation step at a pressure such that it will ensure the establishment of the beads 70, 71 on the seats 75, 76 bearing on the flanged edges.

Experiments concerning the rubber anchoring mixture have shown that to obtain good endurance results, a rubber anchoring mixture containing a synthetic “SBR” elastomer, or butadiene-styrene copolymer, of Tg between −70 can be used. ° and -30 ° C, used alone or in combination with "BR", or polybutadiene. Preferably the BR has a Tg of between -110 ° and -90 ° C. The synthetic elastomer (s) are used in a totalized proportion of at least 50% of the mass total of elastomer, the balance consists of natural rubber ("NR"). The rubber anchoring mixture additionally contains reinforcing fillers such as carbon black and a vulcanization system suitable for obtaining the desired rigidity. The circumferential reinforcing elements are in the examples presented brass plated metal cables. It is therefore necessary that the rubbery anchoring mixture has a high sulfur content and contains additives which promote adhesion with brass (for example metal salts of cobalt or nickel). For example, a sulfur content of between 5 and 8% of the total mass of elastomer is used and a carbon black content of between 60 and 70% of the total mass of elastomer. N347 carbon black can be used preferentially.

Four mixtures were produced and tested to illustrate the characteristics of the rubber anchor mixes according to the invention.

The main characteristics of the formulation of these mixtures are found in the table below.

These four mixtures were tested as follows: rigidity: determination of the modulus of elasticity at 10%> of extension and ambient temperature, - fogging: static fogging test at 150 ° C for 5 hours as described above, and

- thermal stability: rheometry test at 197 ° C for 10 min as described above.

The four mixtures have satisfactory rigidity.

The mixture 1, based on natural rubber only, has a completely insufficient resistance to static creep at high temperature. A rupture of the test pieces is observed after 30 minutes of testing. Its thermal stability is also unsatisfactory since the mixture has a very marked rate of reversion.

Mixture 2 has improved results relative to the former but is also not satisfactory.

Mixtures 3 and 4 pass the static creep and rheometry tests. Their creep resistance is quite correct and their thermal stability at high temperature too. The mixture 3, which comprises three elastomers, presents a slightly more satisfactory result in reversion than the mixture 4.

Pneumatic tests were also carried out with rubber mixtures for anchoring formulations similar to mixtures 1 to 4 of the test. A tire of dimension 30x8.8 R 15/16/225 was tested, comprising:

- As carcass reinforcement two circumferential alignments of reinforcing elements;

- as cables circumferentially oriented steel cables such as those described in FIG. 2, of formula 9.35, and distributed in 7 piles 27 (as illustrated in FIG. 4): • 2 axially innermost piles with 12 and 15 turns ,

• 3 piles between the circumferential alignments 24 and 25 with 17, 14 and 16 turns,

• 2 axially outermost batteries with 11 and 7 turns.

- A crown reinforcement with two layers of reinforcing elements oriented substantially circumferentially made of plies. The tires have shown a suitable suitability for mounting and dismounting operations, but only those comprising a rubber anchoring mixture corresponding to the formulations of mixtures 3 and 4 have shown sufficient endurance resistance of the anchoring of the carcass ply in the beads. Furthermore, the tires corresponding to mixtures 3 and 4 have undergone burst resistance tests and the maximum pressures measured have been of the order of 58 bars. They are also characterized by a rate of elongation of their development between the zero pressure and their operating pressure of 15 bars of the order of 1.5%. These tires have also successfully undergone takeoff tests similar to the standardized tests for the approval of aircraft tires.

The making of such a tire according to the invention can advantageously be carried out on a rigid core imposing the shape of its internal cavity, such as those described by EP 242 840 or EP 822 047, incorporated by reference in the present application. All the constituents of the tire are applied to this core, in the order required by the final architecture, which are arranged directly in their final place, without undergoing any shaping at any time during manufacture. Cooking takes place on a core, which is only removed after the vulcanization phase.

This manufacturing method has the advantage of greatly reducing or even eliminating the prestresses imposed on the reinforcements, particularly those oriented at 0 °, during the traditional phases of conformation.

One can also partially cool the bandage on the core to keep the reinforcing elements in the deformation state imposed during installation.

It is also possible, equivalently, to manufacture the tire on a drum as described in WO 97/47463 or EP 0 718 090, provided that the blank of the tire is shaped before carrying out the laying of the circumferentially oriented cables. .

It is also possible to lay the cables oriented circumferentially on a shape with a geometry identical to the shape targeted in the baking mold. The crown block is then assembled with the complementary tire blank according to transfer techniques known to those skilled in the art, then, still according to known principles, the tire is fitted and pressurized by deployment of a membrane inside the tire.

This embodiment also guarantees the absence of prestresses due to conformation in the vulcanization press.

Whatever the manufacturing method chosen for producing a tire according to the invention in which the means for anchoring the reinforcing elements of the carcass reinforcement in each bead are circumferentially oriented cables axially bordering the circumferential alignments of said said reinforcing elements of the carcass reinforcement, it appears that the combination of cables laid in a circumferential orientation and the rubber anchoring mixture according to the invention allows the production of tires which can be mounted on rims of monoblock type wheels .

In addition, the choice of cables laid in a circumferential orientation in the zone of the bead to ensure the anchoring of the reinforcing elements of the carcass reinforcement makes it possible to obtain satisfactory manufacturing yields; in fact, the choice of these cables allows them to be hooked enough when laid bare enough that they will not come off or simply move before the cooking phase.

The description of the figures has been limited to the case of tires in which the means for anchoring the reinforcing elements of the carcass reinforcement in each bead are circumferentially oriented cables axially bordering the circumferential alignments of said reinforcing elements of the carcass reinforcement. carcass but as stated above, it also relates to tires in which the carcass reinforcement comprises at least one layer of reinforcing elements having a turning area around at least one reinforcing element oriented circumferentially such as a bead wire.

The invention should also not be understood as being limited to the case of mounted assemblies consisting in particular of a one-piece type wheel comprising a hollow base functionality; as explained above, the invention also relates to mounted assemblies consisting of a tire according to the invention and of a standard wheel for aircraft applications consisting of several parts.

Claims

1 - Mounted assembly for an aircraft consisting of a wheel and a tire comprising in particular beads, the inflation pressure of which is greater than 9 bars and whose relative deflection is greater than 30%, said wheel comprising a rim for receiving the tire and more specifically seats receiving the beads of said tire, and said rim comprising a hollow base functionality.

2 - Mounted assembly for aircraft according to claim 1, characterized in that the rim is of the one-piece type. 3 - Mounted assembly for aircraft according to claim 1 or 2, characterized in that the rim seats have a slope greater than 5 °, and preferably less than 15 °.

4 - assembled assembly for aircraft according to one of claims 1 to 3, characterized in that the beads of the tire are ovalizable.

5 - Mounted assembly for aircraft according to one of claims 1 to 4, characterized in that the beads of the tire can be warped.

6 - Mounted assembly for "aircraft according to one of claims 1 to 5, the tire comprising a crown, two sidewalls and two beads, a carcass reinforcement anchored in the two beads and a crown reinforcement, in which the reinforcement of carcass comprises at least one circumferential alignment of reinforcement elements and in which the means for anchoring said reinforcement elements in each bead comprise at least one reinforcement element oriented circumferentially, the carcass reinforcement of the tire comprising at least one layer of reinforcement elements having a turning zone around at least one circumferentially oriented reinforcement element 7. An assembly mounted for aircraft according to claim 6, characterized in that the circumferentially oriented reinforcement element is a rod.

8 - assembly mounted for aircraft according to one of claims 1 to 5, comprising a top, two sides and two beads, a carcass reinforcement anchored in the two beads and a crown reinforcement, in which the carcass reinforcement comprises at least one circumferential alignment of reinforcement elements and in which the means for anchoring said reinforcement elements in each bead comprise at least one circumferentially oriented reinforcement element, the means for anchoring said reinforcement elements in each bead of the tire comprising circumferentially oriented reinforcement elements axially bordering said circumferential alignments of said reinforcement elements of the carcass reinforcement.

9 - assembly mounted for aircraft according to claim 8, characterized in that the circumferentially oriented reinforcing elements are cables. 10 - assembly mounted for aircraft according to one of the preceding claims, the tire comprising in particular a carcass reinforcement, characterized in that the reinforcing elements of the carcass structure of the tire are arranged in a radial orientation.

11 - Wheel for aircraft comprising a rim for receiving a tire comprising in particular beads, and more specifically seats receiving the beads of said tire, the inflation pressure of the mounted assembly consisting of the wheel and said tire being greater than 9 bars and whose relative deflection is greater than 30%), characterized in that said rim has a hollow base functionality.

12 - Wheel for aircraft according to claim 11, characterized in that the rim is of the monobloc type.

13 - Wheel for aircraft according to claim 11 or 12, characterized in that the rim seats have a slope greater than 5 °, and preferably less than 15 °.

14 - Aircraft tire, the inflation pressure of which is greater than 9 bars and the relative deflection of which is greater than 30%, comprising a crown, two sidewalls and two beads, a carcass reinforcement anchored in the two beads and a reinforcement crown, in which the carcass reinforcement comprises at least one circumferential alignment of reinforcing elements and in which the means for anchoring said reinforcing elements in each bead comprise at least one circumferentially oriented reinforcement element, and at least one rubber mix anchor in contact with the circumferential reinforcement and the reinforcing elements of the carcass reinforcement, the beads of the tire being ovalizable.

15 - A tire according to claim 14, characterized in that the beads of the tire can be warped. 16 - Aircraft tire, the inflation pressure of which is greater than 9 bars and the relative deflection of which is greater than 30%, comprising a crown, two sidewalls and two beads, a carcass reinforcement anchored in the two beads and a reinforcement crown, in which the carcass reinforcement comprises at least one circumferential alignment of reinforcing elements and in which the means for anchoring said reinforcing elements in each bead comprise at least one circumferentially oriented reinforcement element, and at least one rubber anchor mixture in contact with the circumferential reinforcement and the reinforcing elements of the carcass reinforcement, said rubber anchor mixture having a modulus of elasticity at a deformation of 10% of less than 20 MPa. 17 - A tire according to claim 16, characterized in that the rubber anchoring mixture comprises at least one synthetic elastomer included in the group of SBR and BR with a total proportion of synthetic elastomer greater than 50% of the total mass d elastomers.

18 - A tire according to claim 16 or 17, characterized in that the rubber anchoring mixture comprises an SBR of Tg between -70 ° and -25 ° C with a proportion by mass greater than 20% of the total mass of elastomers.

19 - A tire according to claim 16 or 17, characterized in that the rubbery anchoring mixture comprises a BR of Tg of between -110 ° and -90 ° C with a proportion by mass of less than 40% of the total mass of elastomers. 20 - A tire according to one of claims 16 to 19, characterized in that the rubbery anchoring mixture withstands without breaking a static creep stress at 150 ° C under an initial stress of 2.35 MPa for at least five hours. 21 - A tire according to claim 20, characterized in that the rubbery anchoring mixture has a static creep rate at 150 ° C under an initial stress of 2.35 MPa less than 2.10 ^"3 min ^{" 1} between three and five hours.

22 - A tire according to one of claims 16 to 21, characterized in that the rubber anchoring mixture has a rate of reversion after 10 min at 197 ° C less than 10% and preferably less than 5%.

23 - A tire according to one of claims 14 to 22, characterized in that the carcass reinforcement comprises at least one layer of reinforcing elements having a turning area around at least one reinforcing element oriented circumferentially.

24 - A tire according to claim 23, characterized in that the circumferentially oriented reinforcement element is a bead wire.

25 - A tire according to one of claims 14 to 22, characterized in that the means for anchoring said reinforcing elements in each bead comprise circumferentially oriented reinforcing elements axially bordering said circumferential alignments, said reinforcement reinforcing elements carcass.

26 - A tire according to claim 25, characterized in that the circumferentially oriented reinforcement elements are cables.

27 - A tire according to claim 26, characterized in that said cables have an aptitude for penetration between 80 and 100%, in that the breaking force of the cables is greater than 150 daN and in that said cables have an elongation at rupture greater than 4%.

28 - A tire according to one of claims 26 or 27, characterized in that the breaking force of the circumferentially oriented cables is less than 400 daN. 29 - A tire according to one of claims 26 to 28, characterized in that the elongation at break of the circumferentially oriented cables is less than 8%.

30 - A tire according to any of claims 26 to 29, characterized in that said circumferentially oriented cables of said anchoring means consist of wires chosen from the group of reinforcements of carbon, tungsten, aramid, fiberglass, or steel.

31 - A tire according to one of claims 26 to 30, the circumferentially oriented cables being metallic, characterized in that said circumferentially oriented cables are heat treated.

32 - A tire according to one of claims 26 to 31, characterized in that the surface of the circumferentially oriented cables comprises an adherent coating, such as a brass coating.

33 - A tire according to claim 14 to 32, characterized in that the reinforcing elements of the carcass structure are arranged in a radial orientation.

34 - A tire according to one of claims 25 to 33, in which, considering ΣRi sum of the extension stiffnesses of the second reinforcements disposed axially internally relative to the carcass reinforcement and considering ΣR _E sum of the extension stiffnesses second reinforcements disposed axially on either side of the carcass reinforcement, we have:

35 - A tire according to claim 34, in which:

36 - A tire according to one of claims 14 to 35, in which, the external surface of the beads comprising a seat, a frustoconical wall of substantially radial orientation adjacent radially inside to a wall whose cross section is an arc of a circle EF of center C and considering a line CD crossing the bead at an angle a = +45 + 5 degrees relative to Tax A of the tire, all of the second reinforcements are disposed at a radial distance from the axis A less than or equal to said CD line. 37 - A tire according to one of claims 14 to 36, in which said bead having an outer surface intended to come into contact with the corresponding surface of the seat and of the hook of said rim, after mounting on said rim and inflation of said tire, the area contact between said outer surface of said bead and said rim extends at least to point B of the hook of maximum radius Rj.

38 - A tire according to claim 37, in which, Φ being the diameter of the circumference of the outer surface of the bead intended to bear against the circumference of the hook of the rim of maximum radius Rj, we have:

Φ = 2 (R _J - ε) with ε between 0.5 and 2 mm.

39 - A tire according to one of claims 14 to 38, wherein said first reinforcements of the carcass reinforcement form back and forth arranged adjacent, with, at each bead, loops connecting each time a go to a return.

40 - A tire according to one of claims 14 to 39, in which said crown reinforcement comprises at least one working block with at least two layers of parallel reinforcements in each layer, oriented substantially circumferentially and of high modulus of elasticity.

41 - A tire according to claim 40, in which said crown comprising a central zone and two lateral zones, said working block further comprises two layers of reinforcing elements of high elastic modulus, oriented substantially circumferentially, axially arranged on either side of the median plane of the tire in the lateral zones of said crown.

42 - A tire according to claim 41, wherein said two layers of reinforcing elements of high modulus of elasticity of said working block are arranged radially inside said two layers of reinforcements oriented circumferentially of said working block.

43 - A tire according to one of claims 40 to 42, in which said working block further comprises two layers of reinforcements, mutually parallel in each layer and crossed from one layer to the next, making an angle α with the circumferential direction, between 5 ° and 35 °, said reinforcements having a high modulus of elasticity.

44 - A tire according to one of claims 40 to 43, wherein said crown reinforcement further comprises, disposed radially outwardly relative to said working block, a protective layer extending axially beyond the axial width of said layer or layers reinforcements with high modulus of elasticity.

45 - Use of a tire as described according to one of claims 14 to 44 in a mounted assembly for aircraft as described according to one of claims 1 to 3.

46 - Use of a tire as described according to one of claims 14 to 44 in an assembly mounted for an airplane whose inflation pressure is greater than 9 bars and whose relative deflection is greater than 30%, consisting of a wheel and tire, said wheel comprising a rim for receiving the tire and more specifically seats receiving the beads of said tire and said wheel being of the multi-part type.

47 - Mounted assembly for an airplane, the inflation pressure of which is greater than 9 bars and the relative deflection of which is greater than 30%, consisting of a wheel and a tire as described according to one of claims 9 to 36, comprising in particular beads, said wheel comprising a rim for receiving the tire and more specifically seats receiving said beads of the tire and said wheel being of the multi-part type.