Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02K—JET-PROPULSION PLANTS
  • F02K1/00—Plants characterised by the form or arrangement of the jet pipe or nozzle; Jet pipes or nozzles peculiar thereto
  • F02K1/54—Nozzles having means for reversing jet thrust
  • F02K1/64—Reversing fan flow
  • F02K1/70—Reversing fan flow using thrust reverser flaps or doors mounted on the fan housing
  • F02K1/72—Reversing fan flow using thrust reverser flaps or doors mounted on the fan housing the aft end of the fan housing being movable to uncover openings in the fan housing for the reversed flow
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
  • B64D29/00—Power-plant nacelles, fairings or cowlings
  • B64D29/06—Attaching of nacelles, fairings or cowlings
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02K—JET-PROPULSION PLANTS
  • F02K1/00—Plants characterised by the form or arrangement of the jet pipe or nozzle; Jet pipes or nozzles peculiar thereto
  • F02K1/78—Other construction of jet pipes
  • F02K1/82—Jet pipe walls, e.g. liners
  • F02K1/827—Sound absorbing structures or liners
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2220/00—Application
  • F05D2220/30—Application in turbines
  • F05D2220/32—Application in turbines in gas turbines
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2250/00—Geometry
  • F05D2250/20—Three-dimensional
  • F05D2250/28—Three-dimensional patterned
  • F05D2250/283—Three-dimensional patterned honeycomb
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
  • F05D2260/00—Function
  • F05D2260/96—Preventing, counteracting or reducing vibration or noise
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T50/00—Aeronautics or air transport
  • Y02T50/60—Efficient propulsion technologies, e.g. for aircraft

Definitions

• the present invention relates to a thrust reverser for an aircraft turbojet engine nacelle and is more precisely in the field of acoustic attenuation of an aircraft propulsion unit, that is to say the assembly formed by a turbojet engine (in particular a turbojet engine) equipped with a nacelle, the propulsion unit possibly including the engine pylon.
• An airplane is driven by several turbojets each housed in a nacelle for channeling the air flows generated by the turbojet engine which also houses a set of actuators providing various functions when the turbojet engine is in operation or stopped.
• actuating devices may include, in particular, a mechanical thrust reversal system.
• a nacelle generally has a tubular structure comprising an air inlet upstream of the turbojet engine, a median section intended to surround a fan of the turbojet engine, a downstream section housing a thrust reverser means and intended to surround the combustion chamber of the turbojet engine. , and is generally terminated by an ejection nozzle whose output is located downstream of the turbojet engine.
• Modern nacelles are intended to house a turbofan engine capable of generating, by means of the fan blades, an air flow part of which, called a hot or primary flow, circulates in the combustion chamber of the turbojet engine, and of which the other part, called cold or secondary flow, circulates outside the turbojet through an annular passage, also called vein, formed between a shroud of the turbojet engine and an inner wall of the nacelle.
• the two air flows are ejected from the turbojet engine from the rear of the nacelle.
• the role of a thrust reverser is, during the landing of an aircraft, to improve the braking capacity thereof by redirecting forward at least a portion of the thrust generated by the turbojet engine.
• the inverter obstructs the cold flow vein and directs the latter towards the front of the nacelle, thereby generating a counter-thrust which is added to the braking of the wheels of the aircraft.
• the structure of an inverter comprises one or more movable covers movable between a closed position or “direct jet” in which they close this passage and an open position or “reverse jet” in which they open in the nacelle a passage for the deviated flow.
• a thrust reverser with grids also known as a cascade reverser
• the reorientation of the air flow is performed by deflection grids, the hood having a simple sliding function to discover or cover these grids.
• the translation of the movable cowl takes place along a longitudinal axis substantially parallel to the axis of the nacelle.
• Reversed thrust flaps actuated by the sliding of the hood, allow an obstruction of the cold flow vein downstream of the deflection grids, so as to optimize the reorientation of the cold flow to the outside of the nacelle.
• Such a hood can be:
• the sliding of a cover between its "direct jet” and “reverse jet” positions is conventionally performed by a plurality of actuators, of the mechano-electric type (for example: worm gear actuated by an electric motor and moving a nut). or hydraulic (cylinders actuated by pressurized oil).
• actuators of the mechano-electric type (for example: worm gear actuated by an electric motor and moving a nut). or hydraulic (cylinders actuated by pressurized oil).
• acoustic attenuation is generally carried out by means of acoustic attenuation panels.
• Such panels may take the form of a sandwich structure, comprising a cellular core framed between two skins, one full and the other perforated so as to be acoustically porous.
• the perforated skin generally called acoustic skin, is intended to be in contact with the cold air flow passing through the nacelle and / or with the flow of hot gases ejected by the turbojet engine.
• SDOF acoustic panels Sound attenuation panels with a degree of freedom of acoustic waves, known as SDOF acoustic panels (for "Single Degree Of Freedom"), are known. Such panels take the form of a sandwich structure as described above.
• DDOF-type panels include a two-storey honeycomb structure. stages being separated by an acoustically porous wall commonly called septum. As for the previously described panels, this honeycomb structure is sandwiched between an acoustically reflecting skin and an acoustically porous skin.
• the DDOF panels have the advantage of attenuating the acoustic waves over a wider frequency band than an SDOF panel.
• the height of the honeycomb structure (and therefore the height of the cavities that it comprises) and the porosity of the acoustic skin and, where appropriate, the septum are optimized so as to maximize the acoustic attenuation and to target the right sound frequency range.
• the manufacturers thus deploy permanent efforts to increase the acoustically treated surface, including equipping the inversion flaps of acoustic panels.
• FIG. 1a shows the nacelle 1 in "direct jet” configuration, that is to say with the thrust reversal system in the retracted position
• Figure lb shows the nacelle in "reverse jet” configuration, that is to say with the thrust reversal system in the deployed position.
• a movable cowl 20 of the rear section 4 is in the retracted position, revealing a set of reversing gates 21.
• Figures 2a and 2b show a section of the rear section 4 of the nacelle 1, respectively when the reverse thrust system is in the retracted position (or direct jet) and deployed position (or reverse jet).
• the thrust reverser system comprises a movable hood 20, which forms the outer surface of the rear section 4 of the nacelle.
• the thrust reversal system further comprises reversing gates 21 and flaps 21 for reversing thrust or locking, rotatable and associated with connecting rods 23.
• the thrust reverser system comprises actuators (Not shown), including electromechanical actuators, for sliding the movable cowl between a retracted position ( Figure 2a) and an extended position ( Figure 2b), and vice versa. This translation takes place along a longitudinal axis of the nacelle, corresponding to the longitudinal axis of the engine.
• the movable cowl 20 is in the retracted position, corresponding to an advanced position in which it provides aerodynamic continuity with the median section of the nacelle;
• the thrust reversing flaps 22 are in retracted position, in which position they are aligned with the inner surface of the movable cowl 20, and housed in a housing 27 of the movable cowl 20;
• the movable cowl is in the extended position, corresponding to a retracted position, in which it discovers the reversing gates 21;
• the thrust reversing flaps 22 are in the deployed position, in which position they at least partially obstruct the vein 24 of cold flow.
• the action of the thrust reverser flaps 22 and the inversion gates 21 makes it possible to redirect the cold flow outside the nacelle forwardly in order to create a counter-thrust.
• the passage in the deployed position of the flaps 22 of thrust reversal is in the example obtained by the action of connecting rods 23 attached to an internal fixed structure 25 of the nacelle.
• FIGS. 3a and 3b show a thrust reversal flap 15 equipped with an acoustic attenuation panel 26, respectively with a single degree of freedom and with a double degree of freedom.
• the acoustic attenuation panel 26 with a degree of freedom comprises a full back skin 28 and a front skin 29, these two skins framing a cellular core 30.
• the front skin 29 is multi-perforated and therefore acoustically porous.
• the front skin 29 forms the outer surface of the thrust reversal shutter.
• the acoustic attenuation panel 26 with two degrees of freedom, is formed by a solid skin 28 and a perforated skin 29 surrounding a cellular core 30.
• the cellular structure comprises two stages separated by a septum 31. This thus makes it possible to improve the acoustic attenuation performance, especially in medium and high sound frequencies, but leads to expensive and heavy acoustic panels.
• the acoustic attenuation panel 26 being installed in the housing 27, it must be sized to accommodate the thrust reversal flaps (and therefore the sound attenuation panel 26), when the flaps reverse thrust are in the retracted position.
• the bulk of the acoustic attenuation panel thus constitutes a disadvantage because it requires in this example to increase the dimensions of the housing, generating discontinuities in the structure of the translating cover.
• the structure of the translating cover to the housing of the thrust reversal flaps has a reduced thickness given the thickness of said flap, which is generally made of a monolithic skin.
• a structure does not offer optimum stiffness.
• the object of the invention is to propose a thrust reverser configured to guarantee an appropriate acoustic attenuation and which makes it possible to gain stiffness and structural strength.
• the invention relates to a thrust reverser for a turbojet engine nacelle comprising at least one movable cowl mounted on a fixed structure of the inverter between a closed position, in which it ensures the aerodynamic continuity of the nacelle and an opening position in which it opens a passage in the nacelle, the thrust reverser further comprising thrust reversing flaps actuated by the sliding of the hood, and movable between: a retracted position, position in which they are aligned with an inner wall of the movable cowl, and housed in a housing of said movable cowl, when the movable cowl is in the closed position, and
• the thrust reverser being remarkable in that the housing of the movable cowl is delimited by a wall of said movable cowl formed at least in part by an acoustic attenuation panel.
• the wall of the movable hood delimiting the housing is formed by a continuous extension of the inner wall of the movable cowl with which the thrust reversal flap is aligned when in the retracted position.
• the wall of the movable hood delimiting the housing is formed by an acoustic attenuation panel in the extension of the acoustic attenuation panel of the inner wall of the movable hood.
• Such continuity of the inner wall which extends to delimit the housing provided to receive the thrust reversing flaps in the closed position can further improve the structural strength of the movable hood and limit any point of weakness and discontinuities in the structure of the translatant cover on the contrary for example of an insert.
• the wall of the movable hood delimiting the housing is formed by an acoustic attenuation panel extending continuously from said housing which it delimits to the inner wall.
• the inner wall of the movable hood is formed by an acoustic panel which extends continuously upstream so as to form the housing by delimiting it.
• the acoustic panel has a downstream portion of the inner wall, which is arranged to be licked by the secondary flow when the turbojet engine is in operation and the thrust reverser is in the closed position, the acoustic panel extending. from the downstream part to an upstream part, upstream of the downstream part, to delimit the housing provided to receive the thrust reversing flaps in the closed position.
• the acoustic panel forming an internal wall has a hook between the upstream portion forming the housing and the downstream portion forming an internal wall so that, in the retracted position of the thrust reversal flaps, the latter are aligned with the inner wall of the hood. mobile, in particular aligned with an inner surface of the inner wall adapted to be licked by the secondary flow in operation.
• the acoustic panels are sound attenuation panels with one degree of freedom of acoustic waves (SDOF) and / or acoustic attenuation panels with two degrees of freedom (2DOF or DDOF).
• the thrust reversal flaps are generally acoustically transparent.
• the wall of the movable cowl defining the housing of the thrust reversal flaps being treated acoustically, it is possible to minimize the acoustic treatment of the flaps themselves. In addition, and surprisingly, it is possible to remove them without significantly deteriorating the acoustic balance of the thrust reverser. Moreover, it increases the overall acoustic surface of the nacelle.
• the thrust reversal flaps have a pierced and / or porous surface.
• the thrust reversal flaps are formed by a monolithic wall, preferably reinforced by stiffeners.
• the invention also relates to a remarkable nacelle in that it comprises a thrust reverser as described above.
• Figure 4 illustrates a schematic sectional view of a thrust reverser according to one embodiment
• Figure 5 illustrates a schematic sectional view of an inner panel of a movable cover of the thrust reverser shown in Figure 4;
• FIG. 6 illustrates a schematic sectional view of an inner panel of a movable cowl of a thrust reverser according to another embodiment
• FIG. 7A illustrates an exploded perspective view of a flap and a portion of the movable cowl provided with a corresponding housing provided for accommodating said flap
• Figure 7B illustrates a sectional view AA of Figure 7A, in assembled position.
• Figure 4 shows a section of a portion of a rear section 4 of a nacelle when the thrust reverser 6 is in the closed position (direct jet).
• upstream and downstream as well as “before” and “back” refer to the direction of flow of the air flow through the nacelle.
• the thrust reverser system 6 comprises a movable hood 20, which forms the outer surface of the rear section 4 of the nacelle.
• the thrust reversal system 6 further comprises reversing grids 21 and thrust reversing flaps 22, rotatable, and associated with connecting rods (not shown).
• the thrust reverser system 6 comprises actuators (not shown), in particular electromechanical actuators, for sliding the movable cowl 20 mounted on a fixed structure of the inverter between a closed position, in which it ensures continuity. aerodynamic of the nacelle 1 and an open position in which it opens a passage 61 in the nacelle 1, and vice versa.
• This translation operates along a longitudinal axis X of the nacelle 1, corresponding to the longitudinal axis of the engine.
• the thrust reverser 6 is configured so that in its retracted position position:
• the movable cowl 20 is in the closed position, corresponding to an advanced position in which it ensures the aerodynamic continuity of the nacelle 1, in particular with the median section of the nacelle 1;
• the thrust flaps 22 are in the retracted position, in which position they are aligned with the inner wall 40 of the movable cowl 20, and housed in a housing of the movable cowl 20, when the movable cowl is in the closed position.
• the movable cowl 20 is in the open position, corresponding to a retracted position, that is to say displaced back or downstream, in which it opens the passage 61 in the nacelle 1 and in particular discovers the grids d inversion 21;
• the flaps 22 of thrust reverser are in the deployed position, in which position they are arranged to obstruct at least paretiellement a vein 24 of cold flow of the nacelle 1 to deflect at least a portion of the flow to the passage 61 open in the nacelle 1, more precisely through the inversion grids 21, when said movable cover 20 is in the open position.
• the action of the thrust reverser flaps 22 and the inversion gates 21 makes it possible to redirect the cold flow outside the nacelle 1, towards the front AV in order to create a counter-thrust.
• the passage in the deployed position of the thrust reverser flaps 22 is in the example obtained by the action of connecting rods attached to an internal fixed structure of the nacelle (not shown).
• the housing 27 of the movable cover 20 arranged to receive the shutters 22 of thrust reversal in the closed position is defined by a wall 41 of said movable cover 20 formed at least in part, and preferably constituted by an acoustic attenuation panel , that is to say that the wall 41 at said housing 27 is treated acoustically.
• flaps 22 of thrust reverser so that they are less bulky. Indeed, the acoustic treatment of flaps 22 of inversion can be reduced accordingly, the acoustic treatment being deported flaps 22 of thrust reversal to the wall 41 which delimits the housing 27 in the closed position.
• the wall 41 of the movable cowl defining the housing has a composite sandwich structure forming an acoustic attenuation panel and is formed more precisely by a continuous extension of the acoustic attenuation panel of the inner wall 40 of the movable cowl 20 with which the cowl thrust reversal is aligned when in the retracted position.
• This wall 41 of the housing is more precisely composed of an acoustic attenuation panel extending continuously from said housing 27 which it delimits to the inner wall 40, in particular to a downstream end 44 of the movable hood 20 forming trailing edge.
• the inner wall 40 of the movable cover 20 is formed by an acoustic composite panel and extends from the downstream end 44 forming trailing edge upstream so as to form the housing 27 by delimiting it.
• the acoustic composite panel extends upstream to an upstream end 45 of the movable cover 20 which comes into substantial contact with the fixed structure 46 of the rear section 4 of the the basket in the closed position.
• This contact is preferably indirect, hereby an interface defined by a seal 50.
• the flaps 22 of thrust reversal are integral with the movable cover 20 by a pivot connection 51 located substantially at the level of the upstream end. 45.
• the acoustic composite panel comprises a downstream portion arranged to be licked by the secondary flow when the turbojet engine is in operation and the thrust reverser is in the closed position.
• the acoustic panel extends from the downstream portion to the upstream portion, upstream of the downstream portion, to delimit the housing 27 provided to receive the flaps 22 of thrust reversal in the closed position.
• Such longitudinal continuity of the acoustic attenuation panel between the upstream and downstream ends of a so-called "bottom" wall of the movable cover 20 forming the wall 41 delimiting the housing 27 and forming an internal wall 40 makes it possible to gain stiffness and structural strength. .
• An off-hook 42 of the acoustic panel separates the upstream part of the downstream part so that, in the retracted position of the thrust reversal flaps 22, the latter are aligned with the inner wall 40 of the movable cowl, in particular aligned with a internal surface 43 of the inner wall 40 provided to be licked by the secondary flow in operation.
• this droche 42 of the inner wall 40 is oriented towards the inside of the mobile cowl and towards the a so that the upstream portion of the acoustic panel is recessed towards the inside of the mobile cowl with respect to the downstream portion. which is licked by the secondary flow in the closed position. In this closed position, it is this withdrawal of the upstream portion 41 of the acoustic panel which creates a recess in the movable cover 20 delimiting the housing 27.
• this unhooked part 42 has an oblique wall 47 connecting the upstream and downstream parts of the acoustic panel, that is to say connecting upstream the wall 41 which delimits the housing 27 in the closed position and, downstream, the inner wall 40 of the movable cover 20.
• the oblique wall 47 is connected to:
• the slope formed by the wall oblique 47 has an angle a less than or equal to 45 degrees relative to the walls 40, 41, at least locally at the drop 42.
• the acoustic panel is formed of a sandwich structure, comprising a honeycomb core, for example of honeycomb type, which is framed between two skins, one full and the other perforated so as to be acoustically porous.
• the perforated skin is intended to be in contact with the cold air flow passing through the nacelle and / or with the flow of hot gases ejected by the turbojet engine.
• acoustic skin acoustic attenuation panel forming the wall 41 of the housing 27, it is intended to be in contact with the cold air flow passing through the nacelle, when the movable cover 20 is in position d opening and flaps 22 in the deployed position of course.
• this acoustic skin is not licked by the cold air flow when the flap 22 is in the retracted position but it still provides a noise attenuation function.
• the acoustic panel is here a sound attenuation panel with one degree of freedom of the acoustic waves (SDOF) but it can be completed or be replaced, as needed by sound attenuation panels with two degrees of freedom (2DOF or DDOF).
• SDOF sound attenuation panel with one degree of freedom of the acoustic waves
• a moving cowl 20 can indeed be of quasi-annular shape, extending without interruption from one side to the other of a suspension pylon of the assembly formed by the turbojet engine and its nacelle, such a cowl being designated by the Anglo-Saxon terms "O-duct", by allusion to the ferrule form of such a hood.
• the movable cover 20 may also comprise two half-covers each extending over a half-circumference of the nacelle, such a cover being designated by the Anglo-Saxon terms "D-duct”.
• the lower wall acoustic attenuation panel 45, 41, 42, 40, 44 of the movable hood 20 extends:
• the acoustic attenuation panel in the form of a sandwich structure as described is intended to form the bottom wall of the associated movable cowl in one piece.
• the sandwich structure has been formed and preferably manufactured by soldering, and in particular after soldering, it forms a unitary unit, thus without any insert, forming a bottom wall 45, 41, 42, 40, 44 of the movable cover 20. Note that other manufacturing processes can be used to obtain the bottom wall of the movable cowl as described.
• the thrust reversal flaps 22 are acoustically transparent, that is to say that they are permeable to the sound frequencies. In other words, this means that the flaps 22 of thrust reversal are not treated acoustically which is possible insofar as the acoustic treatment is offset on the wall 41 defining the housing 27 where the flaps 22 are positioned. closing position.
• This configuration is particularly advantageous for the noise attenuation function by the zone of the acoustic attenuation panel forming the wall 41 of the housing 27 is also effective when the flaps 22 are in the retracted position, because they are acoustically transparent.
• the thrust reversal flaps have a pierced and / or porous surface 220 thus making the flaps 22 of thrust reversal generally acoustically transparent.
• An acoustic path is thus defined from the cold flow vein towards the wall 41 delimiting the housing 27, this through the shutters 22.
• the thrust reversal flaps 22 are formed by a monolithic wall 221, for example made of metal material (s), composite (s), thermoplastic (s), etc. .
• the monolithic wall is reinforced by stiffeners 222.
• the mobile cowl 20 according to the invention therefore has a homogeneous structure unlike the prior art whose lower wall is heterogeneous since it has an acoustically treated inner wall and a housing of the doors which is formed of attached partitions.
• the invention also makes it possible to homogeneity of the bottom wall of the translating cover, to optimize the acoustically treated surfaces and to simplify both the manufacture of the movable cover and the avoidance of manufacturing and fixing stages. reported, that the manufacture of thrust reversing flaps that have a simplified structure.
• the invention is described in the foregoing by way of example. It is understood that the skilled person is able to achieve different embodiments of the invention without departing from the scope of the invention.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Aviation & Aerospace Engineering (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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• 2017
  • 2017-11-10 FR FR1760589A patent/FR3073571A1/fr not_active Withdrawn
• 2018
  • 2018-11-09 CN CN201880071121.1A patent/CN111315977A/zh active Pending
  • 2018-11-09 EP EP18827157.1A patent/EP3707363A1/de not_active Withdrawn
  • 2018-11-09 WO PCT/FR2018/052800 patent/WO2019092383A1/fr not_active Ceased
• 2020
  • 2020-05-11 US US16/871,271 patent/US20200386184A1/en not_active Abandoned

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