Actuation system for aircraft thrust reverser comprising locking hooks

Abstract

The invention relates to an actuation system (6) for actuating a pair of movable parts (4a, 4b) of a thrust reverser (1) of an aircraft (0), comprising: - a main actuator (7); - secondary actuators (8a, 8b); a transmission mechanism (9) configured to simultaneously move the movable elements (8a1, 8b1) of the secondary actuators (8a, 8b) in order to simultaneously move the movable parts (4a, 4b) to their over-retracted positions. The actuation system (6) comprises a locking mechanism (10) comprising a first pair of hooks (10a1, 10a2), a first locking actuator (11a) for simultaneously moving the hooks (10a1, 10a2) and the transmission mechanism (9) counteracting the movement of each of the movable elements (8a1,8b1) whenever at least one of the hooks (10a1, 10a2) in the locking position prevents the movement of all of the movable parts (4a, 4b) via the transmission mechanism.

Description

[0001] ACTUATION SYSTEM FOR AIRCRAFT THRUST REVERSERS COMPRISING LOCKING HOOKS. The invention relates to the field of actuation of aircraft thrust reversers.

[0002] BACKGROUND

[0003] Modern aircraft are therefore increasingly incorporating electrical (and electromechanical) onboard systems which offer many advantages and in particular allow for a reduction in aircraft mass and thus improve the aircraft carbon footprint.

[0004] Improving the carbon footprint is an objective sought by the applicant, this improvement being made possible in particular by using a system allowing a reduction in mass or at least a maintenance of mass but with improved functionalities, such as improved safety and / or an improved lifespan.

[0005] The nacelle of an aircraft turbojet engine is typically equipped with a thrust reverser, which includes moving parts. The simultaneous deployment of these moving parts redirects a portion of the gas flow produced by the turbojet engine forward, thus reducing landing distances by at least partially reversing the direction of the thrust delivered by the engine.

[0006] Traditionally, as illustrated by patent document W002101222A1, moving parts are moved by an actuation system comprising hydraulic cylinders. In document W002101222A1, two hydraulic cylinders are used to move the two moving parts simultaneously. To this end, each of these cylinders is connected to a pair of connecting rods, each of which is connected to one of the two moving parts. Thus, each hydraulic cylinder controls, via the two connecting rods, the simultaneous movement of the two opposing moving parts.

[0007] To function and avoid deforming the moving parts, this hydraulic actuation system requires perfect synchronization of the two hydraulic cylinders.

[0008] Another actuation system, comprising two hydraulic cylinders, is also known from document US5819527A1.

[0009] In this document, each moving part is moved by only one of the hydraulic cylinders that corresponds to it.

[0010] For the moving parts to move together and symmetrically, it is essential that these hydraulic cylinders be perfectly synchronized in their respective movements, which is difficult to guarantee.

[0011] It is also known, for example from document EP861 978B1, to use an electrical actuation system for the thrust reverser, which allows the overall mass of the aircraft to be reduced when it opts for an electrical power distribution.

[0012] We know of a prior art gate thrust inverter, which includes two gates each actuated by an electromechanical actuator, such as an electric cylinder.

[0013] It is known that a failure leading to the in-flight opening of a thrust reverser door is considered a "catastrophic" failure. It is therefore essential to equip the actuation system with an interlocking device to prevent this type of failure, even in the event of simultaneous failure of several components of the actuation system.

[0014] Reliability calculations, safety analyses, and tests have demonstrated that the specified safety objectives are met by equipping each door (moving part) with three independent locks to secure the door in the retracted position, where the door (moving part) is closed so that all the thrust of the engine is directed towards the rear of the turbofan. In the deployed position, a portion of the flow generated by the turbofan is reversed, that is, directed towards the front of the aircraft.

[0015] To avoid the risk of an incident (stall or breakage of parts of the turbojet or nacelle), it is essential that the passage of the thrust reverser doors, hereinafter referred to as the moving parts, from the retracted position to the deployed position only occurs during landing, while the wheels of the aircraft's landing gear are rolling on the ground, and within a given taxiing speed range.

[0016] For this purpose, in some prior art thrust reversers, each door is usually held in the retracted / closed position by two latches directly engaged with the door to hold it in the retracted / closed position, as well as by a tertiary latch acting on the actuator controlling the passage of the door from its retracted position to its deployed position.

[0017] Each tertiary lock is integrated into the electric actuator used to move one of the corresponding doors / moving parts.

[0018] Tertiary locks, for example, are similar to the one described in document EP 3 593 011 B1.

[0019] This results in an actuation system that is as reliable and safe as traditional hydraulic actuation systems, while minimizing the mass of the thrust reverser. However, further efforts are being made to reduce the mass and size of this actuation system while simultaneously improving its safety.

[0020] OBJECT

[0021] The invention aims to reduce the mass of the thrust reverser actuation system, in particular of a thrust reverser of the gate type.

[0022] SUMMARY

[0023] To achieve this goal, an actuation system is proposed, arranged to actuate at least one pair of moving parts of an aircraft thrust reverser, preferably a two-door thrust reverser.

[0024] The actuation system, comprising:

[0025] - a main actuator;

[0026] secondary actuators each comprising a movable element between extreme positions.

[0027] The actuation system according to the invention is essentially characterized in that each moving element is connected to a single corresponding moving part to move it between a retracted position and a deployed position as a function of the movement of the moving element between its extreme positions (a moving part is preferably a door), the actuation system also comprising:

[0028] - a transmission mechanism connected on one side to the main actuator, which includes an electric motor to drive the transmission mechanism, and on the other side to the secondary actuators, the transmission mechanism being configured to, under the effect of the main actuator, simultaneously drive the movement of the moving elements of the secondary actuators between their extreme positions and to simultaneously move the moving parts to their respective over-retracted positions or to their respective deployed positions, the actuation system also includes a locking mechanism comprising a first pair of hooks, each pivotally mounted between a locking position and a release position, and a first locking actuator to simultaneously move each of the hooks of the first pair of hooks from the locking position to the release position,the actuation system selectively adopting: - a flight configuration in which each of said moving parts is in a retracted position situated between the over-retracted position and the deployed position, the hooks of the first pair of hooks each being in a locked position so that each given hook of the first pair of hooks prevents the movement of one of said moving parts corresponding to it from the retracted position to the deployed position; and,

[0029] a thrust reversal configuration in which each of said moving parts is in the deployed position; and

[0030] the transmission mechanism being further arranged to oppose the movement of each of the moving elements as soon as at least one of the hooks in the locked position prohibits said movement of the corresponding moving part from the retracted position to the deployed position and in which each secondary actuator is mechanically connected to the main actuator via the transmission mechanism so that all the moving elements of the secondary actuators are driven and moved together between their over-retracted and deployed positions by said electric motor of the main actuator.

[0031] Thanks to the invention, the same first actuator of the locking mechanism makes it possible to act on the respective positions of the two hooks of the same pair of hooks in order to selectively lock or release the two moving parts of the thrust reverser and thus selectively prohibit or allow their movements, under the effect of the movement of the moving elements of the secondary actuators, towards their second positions.

[0032] The actuation system according to the invention is also advantageous because it allows the actuation of the moving parts of the thrust reverser to be secured without having to use: - an additional tertiary lock to selectively lock the transmission mechanism or the main actuator; and / or - a locking actuator for each moving part that one wants to lock in the retracted position.

[0033] In this sense, the actuation system according to the invention makes it possible to limit the number of locks and consequently the number of locks to be ordered, without compromising the critical function of locking the moving parts in the retracted position.

[0034] In their second positions, these moving parts of the thrust reverser allow for a reversal of the direction of the thrust generated by the reactor.

[0035] This unlocking function, using the same actuator acting on both hooks of a given pair of hooks, allows for a reduction in mass without compromising the security of the locking function of the pair of moving parts of the thrust reverser.

[0036] Indeed, even if one of the hooks in the pair of hooks breaks, the other hook in the pair of hooks, which is in the locking position, continues to act on the corresponding moving part to prevent it from moving from the retracted position to the deployed position. The transmission mechanism then opposes the movement of the other moving part, since one of the hooks is still in the locking position and prevents the movement of the corresponding moving part from its retracted position to its deployed position.

[0037] The locking function of the moving parts in their respective retracted positions is thus secured since in the event of breakage of one of the hooks, the other of the hooks acts with the transmission mechanism to maintain the two moving parts in their retracted positions (the moving parts can only move together, from their retracted positions to their deployed positions).

[0038] This avoids a critical risk for the aircraft of having an accidental movement of only one of the moving parts towards the deployed position while the other of these moving parts would remain in the retracted position.

[0039] Such a situation would be critical for aircraft safety since it would induce an accidental loss of thrust on one of the engines with an asymmetric thrust reversal.

[0040] The transmission mechanism prohibits any possibility of movement of a single moving part from its retracted position to its deployed position (the moving parts can only move together / at the same time, from their respective retracted positions to their respective deployed positions).

[0041] Preferably, the actuation system according to the invention comprises a control unit configured to control the main actuator and each locking actuator, the control unit being arranged to control the transition from the flight configuration to the thrust reversal configuration by successively controlling:

[0042] - to the main actuator to move the moving parts from their retracted positions to their over-retracted positions; then (while the moving parts are in their over-retracted positions)

[0043] - each locking actuator moves each of the hooks from its locking position to its release position; then (while the hooks are held in their release positions by the control unit of each locking actuator)

[0044] - to the main actuator to move the moving parts from their respective over-retracted positions to their respective deployed positions while keeping each of the hooks in the release position (keeping the hooks in the release position is controlled by the control unit which controls each locking actuator).

[0045] This embodiment secures the aircraft against the risk of accidental transition from flight configuration to thrust reversal configuration.

[0046] Indeed, when the moving parts are in their retracted positions and the hooks are in their locking positions, i.e., when the actuation system is in flight configuration, then the transition from flight configuration to thrust reversal configuration is only possible if:

[0047] - each moving part is first moved from its retracted position to its over-retracted position; then each hook is moved from its locking position to its release position; then

[0048] - while the hooks are held in the release position, the two moving parts are moved together to their respective deployed positions.

[0049] If one of the hooks had remained stuck in the locked position, then it would have the effect of preventing the corresponding moving part from moving from the retracted position to the deployed position, and the transmission mechanism would then oppose the movement of the two moving parts beyond their retracted positions to their deployed positions.

[0050] The combination of the control unit, hooks, and transmission mechanism of the actuation system according to the invention allows: - passive mechanical protection against the risk of accidental switching to the thrust reversal configuration; and

[0051] - an active securing since only the synchronization of the commands of the main actuator and each locking actuator by the control unit allows the mechanical unlocking necessary for the synchronized movement of the moving parts to their respective deployed positions.

[0052] In another aspect, the invention relates to a thrust reverser comprising an actuation system as defined above. The thrust reverser may, in particular, be a gated thrust reverser.

[0053] The invention also relates, in another aspect, to a turbojet nacelle comprising such a thrust reverser.

[0054] The invention will be better understood in light of the following description of particular, non-limiting embodiments of the invention.

[0055] BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Reference will be made to the attached drawings, among which:

[0057] [Fig. 1] Figure 1 represents an aircraft 0 comprising two turbojet engines 3, each turbojet engine 3 being arranged in a corresponding nacelle 2, each turbine T of turbojet engine 3 being able to rotate in the nacelle 2 to generate a flow to push the aircraft by reaction, each nacelle 2 includes a thrust reverser 1, the thrust reverser 1 comprising a thrust reverser actuation system 6 according to an example of the invention;

[0058] [Fig. 2] Figure 2 represents a nacelle 2 equipped with a thrust reverser 1 equipped with the thrust reverser actuation system 6 according to an example of the invention;

[0059] [Fig. 3] Figure 3 represents a first embodiment of thrust reverser 1 according to the invention equipped with a thrust reverser actuation system 6 having a main actuator 7 comprising an electric motor (electromechanical actuator) and a transmission mechanism 9 of the transmission members 9a, 9b arranged in parallel and each connected on one side to the electric motor 7a and on the other side to one of the secondary actuators 8a, 8b which corresponds to it in order to drive it; [Fig. 4] Figure 4 represents a second embodiment of thrust reverser 1 according to the invention equipped with a thrust reverser actuation system 6 with the transmission mechanism 9 equipped with two transmission members 19a, 19b which are here mounted in series to drive the secondary actuators 8a, 8b;

[0060] [Fig. 5] Figure 5 represents a third embodiment of thrust reverser 1 according to the invention equipped with a thrust reverser actuation system 6 where the main actuator is of the hydraulic type and with a mechanical synchronization device 320 linking the secondary actuators 8a, 8b together so that the moving parts 4a, 4b move together and symmetrically;

[0061] [Fig. 6] Figure 6 represents part of the locking mechanism, with a detail of the first pair of hooks 10a1, 10a2 which are each J-shaped and are each mechanically connected to a sliding rod of the first locking actuator 11a to be simultaneously moved between their release and locking positions.

[0062] In each of the following embodiments of the actuation system 6 (see in particular the three embodiments illustrated in Figures 3 to 5), the actuation system 6 is arranged to actuate at least one pair of moving parts 4a, 4b of a thrust reverser 1 of an aircraft 0.

[0063] The actuation system 6 comprises:

[0064] - a main actuator 7;

[0065] - secondary actuators 8a, 8b each comprising a moving element 8al, 8bl between extreme positions, each moving element 8al, 8bl being connected to a corresponding moving part 4a, 4b to move it between an over-retracted position and a deployed position according to the displacement of the moving element 8al, 8bl between its extreme positions.

[0066] In other words, each given moving part 4a, 4b is connected to a corresponding moving element 8al, 8bl such that the movement of this moving element between its extreme positions causes the movement of the moving part 4a, 4b between its over-retracted and deployed positions via the retracted position.

[0067] The over-retracted position of a given moving part 4a, 4b is a position adopted by the moving parts to promote the evacuation of the Ex flow from the reactor 13 integrated in the nacelle 2 towards the rear of the aircraft 0 and to minimize / prohibit the evacuation of the reverse flow Fr towards the front of the aircraft 0.

[0068] The retracted position of each given moving part 4a, 4b is close to the over-retracted position, this retracted position is illustrated in figure 6, the moving parts 4a, 4b illustrated in solid lines are in their respective retracted positions.

[0069] The retracted positions are adopted during the aircraft's flight.

[0070] Each retracted position of a given moving part 4a, 4b is far from the deployed position of that given moving part, which is adopted when thrust reversal is activated. In Figure 6, the deployed positions of the moving parts are shown as dashed lines.

[0071] When the moving parts 4a, 4b are in the over-retracted position, the flow Fx generated by the turbojet 3 is entirely evacuated towards the rear of the aircraft 0 (to maximize rearward thrust) and the evacuation of flow from the reactor towards the front of the reactor / nacelle is prohibited.

[0072] The deployed position of each moving part 4a, 4b is chosen to allow the evacuation of a reverse flow Fr generated by the turbojet 3 towards the front of the nacelle / aircraft. This reverse flow Fr allows at least a partial reversal of the thrust generated by the turbojet 3.

[0073] The movable parts 4a, 4b are placed in their respective deployed positions during the landing phase, while the wheels of the aircraft's landing gear are rolling on the ground and the aircraft is decelerating and is within a speed range compatible with the deployment of movable parts (to avoid the admission to the turbine of debris present on the ground, the deployment of movable parts 4a, 4b is avoided when the aircraft is at rest).

[0074] With reference to the embodiments illustrated in figures 3, 4, 5 and 6, the actuation system 6 also includes a transmission mechanism 9 connected on one side to the main actuator and on the other side to the secondary actuators.

[0075] This transmission mechanism 9 is configured to, under the effect of the main actuator 7, simultaneously drive the movement of the moving elements 8al, 8bl of the secondary actuators 8a, 8b between their extreme positions and simultaneously move the moving parts 4a, 4b towards their respective over-retracted positions or towards their respective deployed positions.

[0076] In other words, under the mechanical (figure 4) or hydraulic (figure 5) effect of the main actuator 7 on the transmission mechanism 9, the transmission mechanism 9 simultaneously moves all the moving parts 4a, 4b between their respective over-retracted and deployed positions.

[0077] The actuation system 6 also includes a locking mechanism 10 comprising a first pair of hooks 10a1, 10a2.

[0078] Each hook is mounted to pivot between a locking position and a release position.

[0079] Each hook here has a "J" shape, the hooked end of the "J" shape being designed to mechanically engage with a complementary hollow form formed in the corresponding moving part 4a, 4b or in a corresponding intermediate piece that is attached to said corresponding moving part. Thus, as long as the hooked end of the J shape is not completely free of its corresponding complementary hollow form, this hook cannot move to its release position.

[0080] The hook 10a1 is associated with the movable part 4a to selectively prevent its movement from the retracted position to the deployed position.

[0081] The hook 10a2 is associated with the movable part 4b to selectively prevent its movement from the retracted position to the deployed position.

[0082] The hook 10b1 is associated with the movable part 4a to selectively prevent its movement from the retracted position to the deployed position.

[0083] The hook 10b2 is associated with the movable part 4b to selectively prevent its movement from the retracted position to the deployed position.

[0084] Thus, the pair of hooks 10a1, 10a2, like the pair of hooks 10b1, 10b2, allows action on two opposing moving parts 4a, 4b. As can be seen from Figure 6, which illustrates the first pair of hooks, the locking mechanism 10 also includes a first locking actuator 11a to simultaneously move each of the hooks 10a1, 10a2 of the first pair of hooks from the locked position to the released position.

[0085] To this end, each J-shaped hook end opposite the hooked end of the J-shape extends into a hollow part of a sliding rod 111a of the first locking actuator 11a so that each hook of the first pair of hooks pivots according to a sliding position of the sliding rod (111a).

[0086] The hooks of the second pair of hooks all have the same "J" shape but they are moved together between their respective locking and release positions by a second locking actuator 11b separate from the first locking actuator 11a.

[0087] Similarly, each hook end of the second pair of hooks that is opposite the hooked end of the J-shape extends into a hollow part of a sliding rod of the second locking actuator 11b so that each hook of the second pair of hooks pivots according to a sliding position of the sliding rod.

[0088] The actuation system 6 selectively adopts: - a flight configuration in which each of said moving parts 4a, 4b is in a retracted position located between the over-retracted position and the deployed position, the hooks of the first pair of hooks 10a1, 10a2 each being in a locked position so that each given hook of the first pair of hooks 10a1, 10a2 prevents the movement of one of said moving parts 4a, 4b corresponding to it from the retracted position to the deployed position; and

[0089] a thrust reversal configuration in which each of said moving parts 4a, 4b is in the deployed position.

[0090] The expression "retracted position located between the over-retracted position and the deployed position" means that when moving a given moving part from one of the over-retracted or deployed positions to the other of these positions, the given moving part necessarily passes through the retracted position.

[0091] The transmission mechanism 9 is further arranged to oppose the movement of each of the moving elements 8al, 8bl as soon as at least one of the hooks lOal, 10a2 in the locking position prohibits said movement of the corresponding moving part 4a, 4b from the retracted position to the deployed position.

[0092] Thus the actuation system according to the invention makes it possible, without having to increase the number of locking actuators and without having to complicate the actuation system, to secure the locking function of the moving parts 4a, 4b, which limits the risk of having an accidental passage of at least one of the moving parts 4a, 4b towards its deployed position.

[0093] Thanks to the transmission mechanism 9, the moving part 4a corresponding to a given hook lOal which would be broken remains blocked in its retracted position as long as the other of the moving parts 4b remains blocked by the hook 10a2 which corresponds to it.

[0094] Thus, the actuation system 6 allows, without an increase in mass, the securing of the locking function of the moving parts 4a, 4b in retracted positions, since if a given hook acts directly on the locking of one of the moving parts which corresponds to it, it also acts indirectly on the locking of the other of the moving parts because the transmission mechanism 9 links these two moving parts 4a, 4b together so that they can only be moved simultaneously / together from their retracted positions to the respective second positions of these moving parts 4a, 4b.

[0095] The transmission mechanism 9 is preferably arranged to simultaneously position the moving parts 4a, 4b in their respective retracted positions and to simultaneously position the moving parts 4a, 4b in their respective deployed positions.

[0096] This characteristic of simultaneous positioning of the moving parts in their over-retracted or deployed positions allows the variation of the thrust during the movement of the moving parts 4a, 4b to be as predictable and symmetrical as possible since these moving parts arrive together in their deployed positions and arrive together in their over-retracted positions.

[0097] Preferably, as illustrated in the embodiments of Figures 3, 4, and 5, the locking mechanism 10 further comprises a second pair of hooks 10b1, 10b2, each pivotally mounted between a locking position and a release position, and a second locking actuator 11b for simultaneously moving each of the hooks of the second pair of hooks 10b1, 10b2 from its locking position to its release position. In said flight configuration, the hooks of the second pair of hooks 10b1, 10b2 are each in the locking position such that each given hook of the second pair of hooks 10b1, 10b2 prevents the movement of one of said corresponding movable parts 4a, 4b from the retracted position to the deployed position.

[0098] With this embodiment, each moving part 4a, 4b is locked in the retracted position by means of two hooks which belong to two separate pairs of hooks respectively controlled by separate locking actuators 11a, 11b.

[0099] Thus the hooks lOal and lObl allow the first moving part 4a to be locked in its retracted position, the unlocking of these hooks 10a1, 10b1 being done by actuation of the first and second locking actuators 11a, 11b.

[0100] The hooks 10a2 and 10b2 allow the second moving part 4b to be locked in its retracted position, the unlocking of these hooks 10a2, 10b2 always being done by actuation of the first and second locking actuators 11a, 11b.

[0101] This embodiment is therefore advantageous because it greatly secures the locking function of the moving parts, since unlocking requires, on the one hand, moving all the hooks of all the hook pairs into their release positions (here, 4 hooks) and, on the other hand, a simultaneous actuation of the two secondary actuators 8a, 8b under the effect of the main actuator 7, the transmission mechanism 9 being arranged to oppose the movement of only one of the moving parts and to allow only the simultaneous movement of the two moving parts 4a, 4b. Preferably, one of the hook pairs is called internal ("inboard") because it is located between one side of the turbojet and the aircraft fuselage, while the other hook pair is called external ("outboard") because it is located on the other side of the turbojet, opposite the aircraft fuselage.

[0102] Preferably each given hook of the second pair of hooks 10b1, 10b2 is intended to come into mechanical contact against a second intermediate mechanical part subjected to the corresponding moving part 4a, 4b in order to prevent its movement from the retracted position to the deployed position.

[0103] The hook, mechanically engaged against the second intermediate mechanical part, is arranged to allow movement of the corresponding moving part from the retracted position to the over-retracted position while prohibiting movement from the retracted position to the deployed position.

[0104] Preferably, in said thrust reversal configuration, to avoid a risk of interaction with the hooks:

[0105] - each hook of the first pair of hooks 10a1, 10a2 is preferentially held in the release position; and - each hook of the second pair of hooks 10b1, 10b2 is preferentially held in the release position.

[0106] It should be noted that each given hook of any pair of hooks is arranged so that when it is in the locked position and mechanically engaged against an intermediate mechanical part subjected to the corresponding given moving part, then that given hook prevents the movement of that given moving part from the retracted position to the deployed position while allowing the movement of that given moving part from the retracted position to the over-retracted position.

[0107] In the embodiments illustrated in Figures 3 and 4, the main actuator 7 includes an electric motor 7a to drive the transmission mechanism 9, each secondary actuator 8a, 8b being mechanically connected to the main actuator 7 via the transmission mechanism 9 so that all moving parts 8al, 8bl of the secondary actuators are driven and moved together between their extreme positions by said electric motor 7a of the main actuator 7 (the term electric motor refers to electromechanical actuators).

[0108] The actuation of the two secondary actuators by means of an electric motor 7a of the main actuator is an embodiment favorable to a reduction of the mass of the actuation system 6 of the thrust reverser.

[0109] In the embodiment illustrated in Figure 3, the transmission mechanism 9 comprises, for each secondary actuator 8a, 8b, a separate transmission member 9a, 9b, each secondary actuator 8a, 8b being connected to the main actuator 7 by only one of said transmission members 9a, 9b which corresponds to it.

[0110] In this embodiment of Figure 3, each transmission member 9a, 9b mechanically connects the electric motor 7a of the main actuator 7 to one of the secondary actuators 8a, 8b which corresponds to it in order to drive the moving elements of these secondary actuators according to the displacement induced by the electric motor 7a.

[0111] Thus, the separate transmission components 9a, 9b are mechanically coupled together via the electric motor 7a so that these transmission components 9a, 9b operate exclusively together.

[0112] This parallel arrangement of the transmission components 9a, 9b is favorable to a positioning of the electric motor 7a between the secondary actuators 8a, 8b, which can be useful to facilitate a symmetrical arrangement of the different constituent elements of the actuation system around the turbine T of the turbojet 3.

[0113] This embodiment also allows for transmission components 9a, 9b to be identical to each other, thus limiting the number of part references to be manufactured.

[0114] In the embodiment illustrated in Figure 4, which is an alternative to that of Figure 3, said secondary actuators 8a, 8b comprise a first secondary actuator 8a and a second secondary actuator 8b and the transmission mechanism 9 comprises a first transmission member 19a connecting the main actuator 7 to the second secondary actuator 8b, and a second transmission member 19b connecting the second secondary actuator 8b to the first secondary actuator 8a.

[0115] The moving element 8al of the first secondary actuator 8a is moved here by the main actuator 7 (which includes an electric motor 7a) by transmission of drive forces via the first transmission member 19a and via the second transmission member 19b. In this embodiment of Figure 4, the transmission mechanism 9 has: - a first transmission member 19a for transmitting drive forces generated by the electric motor 7a, from the motor 7a to the second secondary actuator 8b; and - a second transmission member 19b which is mechanically connected to the first transmission member 19a so that drive forces generated by the electric motor 7a are transmitted to the second transmission member 19b via the first transmission member 19a.

[0116] This series arrangement of the transmission components 19a, 19b is favorable to a distance of the electric motor 7a from the secondary actuators 8a, 8b.

[0117] This embodiment facilitates the arrangement of the various elements of the actuation system 6 around the turbine T of the turbojet 3 (for example, the location of the electric motor 7a can be moved to an area less exposed to vibrations and / or high temperatures generated by the reactor).

[0118] In any one of the embodiments of the system 6 according to the invention, the transmission mechanism 9 can extend at least in part into a peripheral annular reactor area surrounding a rotating turbine T of the reactor 3.

[0119] One of the moving parts 4a of the pair of moving parts is then located on a first side of the turbine T and the other of the moving parts 4b of the pair of moving parts is located on a second side of the turbine T which is opposite to said first side.

[0120] At least one of the secondary actuators 8a is disposed on the first side of the turbine while the other of said secondary actuators 8b is disposed on the second side of the turbine T, in said peripheral annular zone of the reactor.

[0121] This embodiment allows the movement of the movable parts arranged on either side of the turbine T to be controlled. These movable parts can be doors or buckets mounted pivoting or sliding relative to a support structure of the nacelle 2 between said deployed and over-retracted positions.

[0122] In some embodiments, the transmission mechanism 9 may include one or more preferably rigid, or possibly flexible, shafts mounted for rotation (for example a flexible shaft is mounted for rotation in a corresponding sheath) to transmit a drive force generated by the main actuator 7 to the secondary actuators 8a, 8b to move their respective moving elements 8al, 8bl.

[0123] This method of implementation is simple to implement, but the capacity for transmitting forces proves to be limited.

[0124] To increase the force transmission capacity between main actuator 7 and secondary actuators 8a, 8b, the transmission mechanism 9 can be made to include a first force transmission chain to transmit to at least one of the secondary actuators 8a, a first drive torque generated by the main actuator 7 and a second force transmission chain to transmit to at least one other of said secondary actuators 8b, a second drive torque generated by the main actuator 7.

[0125] The first force transmission chain extends into the peripheral annular zone of the turbine T, on the first side of the turbine, while the second chain extends into the peripheral annular zone of the turbine T on the second side of the turbine.

[0126] The first chain includes at least one first right-angle cardan shaft and at least two rotating shafts connected to each other via the first right-angle cardan shaft to transmit said first drive torque.

[0127] The second chain includes at least one second right-angle cardan shaft and at least two rotating shafts connected to each other via the second right-angle cardan shaft to transmit said second drive torque.

[0128] These shafts connected to the right-angle dial drives are thus shorter and less prone to deformation than a single flexible shaft extending from the main actuator to the secondary actuator.

[0129] These shafts connected to the cardan angle drives can be rigid and possibly telescopic to transmit a greater torque / force while accepting geometric variations inherent in the deformations of the nacelle.

[0130] This method of embodiment is also advantageous because the right-angle cardan shafts allow transmission of drive torques while accepting variations in angles between the shafts connected to each other by the right-angle shafts.

[0131] With this particular embodiment, the geometry and dimensions of the actuation system 6 can be adapted according to the dimensions of the turbine T to be equipped with the thrust reverser and the dimensions and geometries of the nacelle which receives the actuation system 6.

[0132] In this embodiment, the rotating shafts are preferably rigid and connected to cardan shafts, however it could be envisaged that at least some of said rotating shafts are flexible shafts.

[0133] A flexible shaft is a shaft that can bend along its length while maintaining high torsional stiffness to oppose its twisting.

[0134] In each of the embodiments where the main actuator 7 includes an electric motor 7a (for example three-phase), a sensor 110 can be used to measure a current position representative of the position of the transmission mechanism 9 mechanically driven by the electric motor 7a.

[0135] In any one embodiment, the aircraft 0 comprises a set of power sources 120, including a single-phase AC voltage source (e.g., 115VAC), a three-phase AC voltage source (e.g., 115VAC or possibly a DC voltage source), and a DC voltage source (typically 28VDC). The aircraft also comprises an electrical power distribution unit ENU (shown in Figures 3 and 4, which correspond to electrical control modes of the main actuator 7) and / or a hydraulic power distribution unit DCU (shown in Figure 5, which corresponds to the hydraulic control mode of the main actuator 7).

[0136] The actuation system 6 according to the invention includes a control unit Cl which allows the power supply of the main actuator 7 to be controlled: - either via the electrical power distribution unit ENU (in the case of electrical control of a main actuator 7 of electromechanical type as in figures 3 and 4);

[0137] - either via the hydraulic power distribution unit DCU (in the case of hydraulic control of a main actuator 7 as in figure 5).

[0138] Aircraft 0 also includes a FADEC 150 (for Full Authority Digital Engine Control) controller for turbojet engine 3. The FADEC 150 controller includes two channels: channel #A and channel #B.

[0139] The electrical power distribution unit ENU receives DC voltage VDC and three-phase AC voltage VAC 3p (or where applicable another voltage not necessarily three-phase), as well as control signals Sc produced by the two channels of the FADEC 150 controller which are connected to the control unit Cl.

[0140] In the embodiments of figures 3 and 4 (main actuator 7 of electromechanical type), depending on commands generated by the control unit Cl and delivered via the FADEC channels, the electrical power distribution unit ENU generates the pilot currents Ip to drive the electric motor 7a of the main actuator 7.

[0141] In the embodiment of Figure 5 (main actuator 7 of hydraulic type), depending on commands generated by the control unit Cl and delivered via the FADEC channels, the hydraulic power distribution unit DCU, via its hydraulic distributor 70, delivers hydraulic power to the secondary actuators 8a, 8b of hydraulic cylinder type.

[0142] In the electrical embodiments illustrated in Figures 3 and 4, the sensor 110 (which can be integrated into the motor 7a) is functionally linked with the control unit Cl to ensure control of the motor 7a. In the embodiment of Figures 3 and 4, the first locking actuator 11a and the second locking actuator 11b are electrically connected to the actuator power supply assembly 120 so that, according to commands generated by the control unit Cl, they are electrically powered (for example, with 115-volt AC or, for example, with 28-volt DC) to move the corresponding hooks 10a1, 10a2, 10b1, 10b2 to their respective release positions.

[0143] In the embodiments illustrated in Figures 3, 4, and 5, the actuation system 6 also includes sensors 31a, 31b, 32a, and 32b for verifying that the hooks 10a1, 10a2, 10b1, and 10b2 are in the locked position. As previously mentioned, the retention function of the doors 4a and 4b (moving parts 4a and 4b) performed by the hooks is a fundamental function, and it is necessary that the position of each hook be individually monitored.

[0144] We therefore monitor that, when the thrust reverser 1 is in flight configuration, the hooks are in the locking position, and therefore that the doors 4a, 4b are locked in the retracted position.

[0145] These sensors include, for each door 4a, 4b, a sensor 31a, 31b located on the fuselage side (inboard) and a sensor 32a, 32b located on the outside (outboard). Sensor 31a is associated with hook lOal. Sensor 32a is associated with hook lObl. Sensor 31b is associated with hook 10a2. Sensor 32b is associated with hook 10b2.

[0146] These sensors 31a, 31b, 32a, 32b are, for example, switches or inductive proximity sensors. Each sensor 31a, 31b, 32a, 32b has a sensing cell, which cooperates with the associated hook to detect its presence in the locked position. Each sensor also includes an electronic device comprising two redundant electronic units 35, 36. Each electronic unit 35, 36 acquires the measurements produced by the sensing element of the sensor and transmits these measurements to a separate channel of the FADEC 150 controller (to channel #A of the FADEC 150 for unit 35 and to channel #B of the FADEC 150 for unit 36), which communicates with the control unit Cl. The control unit Cl thus receives information from the sensors 31a, 31b, 32a, 32b regarding their respective current positions.

[0147] The actuation system 6 also includes sensors 41a, 41b designed to verify that the moving parts / doors 4a, 4b are in their respective deployed positions. Each door 4a, 4b is associated with a corresponding sensor 41a, 41b.

[0148] Each sensor 41a, 41b is, for example, a discrete sensor if only a single position (deployed position) of the gate 4a, 4b needs to be captured, or a continuous sensor if a range of variation in the position of the gate 4a, 4b is desired. These sensors 41a, 41b are, for example, switches or inductive proximity sensors for a single position, or variable linear sensors (differentiated or not) for continuous measurement.

[0149] Each sensor 41a, 41b also includes an electronic device comprising two electronic units 35, 36 of the type previously described for the other sensors 31a, 31b, 32a, 32b. The electronic units 35 of sensors 41a or 41b transmit the measurements to channel #A of the FADEC 150 and the electronic units 36 of sensors 41a or 41b transmit the measurements to channel #B of the FADEC 150.

[0150] These measurements are received by the control unit Cl of the actuation system which communicates with or is integrated into the FADEC 150.

[0151] The control unit Cl monitors the positions of the main actuator 7 / transmission mechanism 9, hooks and moving parts 4a, 4b in order to detect possible failures of the control system 6. This can be useful for example to inform maintenance operators of possible disjunctions which can facilitate maintenance.

[0152] Thus, the door hooks are monitored in such a way that the loss of a hook (breakage or failure to engage in the complementary intermediate part) is detectable during a flight cycle.

[0153] This detection can be carried out before takeoff by sizing the inverter with this in mind.

[0154] Thus, it is possible to ensure the engagement of the hooks before takeoff and thus avoid having several dormant failures on the thrust reverser locking.

[0155] It is also possible to add a monitoring element for the force transmission chain going from the main actuator 7 to the gates 4a, 4b via the secondary actuators 8a, 8b in order to monitor that the force path is not lost / interrupted.

[0156] The risk of loss of force path or loss of locking function by the hooks is identified at the control unit level. Additional force or locking function loss measurement interfaces communicating with the control unit Cl can be used to measure these force path and / or locking function losses.

[0157] For example, sensors that measure electrical continuity are used to ensure the mechanical integrity of the interface. Alternatively, laser or ultrasonic sensors could be used to monitor the topology of the interfaces.

[0158] We will now describe the particular embodiment of the invention illustrated in Figure 5, in which the main actuator 7 comprises a hydraulic distribution element of the solenoid valve type 70 and the secondary actuators 8a, 8b are of the hydraulic cylinder type.

[0159] The transmission mechanism 9 includes a hydraulic circuit 330 and a mechanical synchronizing device 320 linking the secondary actuators 8a, 8b together so that the moving elements 8al, 8bl of the secondary actuators 8a, 8b move exclusively together (i.e. exclusively simultaneously and in a synchronized manner) under the effect of a hydraulic pressure delivered by the main actuator 7 to the secondary actuators 8a, 8b, via the hydraulic circuit 330 of the transmission mechanism 9.

[0160] In this hydraulically controlled embodiment of Figure 5, the mechanical synchronization device 320 is arranged to connect all the secondary actuators 8a, 8b together so as to have a constant motion transmission ratio between each pair of two moving elements 8al, 8bl of the secondary actuators 8a, 8b connected together via the mechanical synchronization device 320.

[0161] This mechanical synchronization mechanism 320 can include a pair of gear trains each driven to rotation in response to the movement of one of the moving elements 8al, 8bl of the secondary actuators 8a or 8b of the hydraulic cylinder type to which it is connected (a cylinder rod here constituting a moving element of a secondary actuator).

[0162] Thus, a first gear train is driven in rotation by a moving element of the first secondary actuator 8a of the hydraulic cylinder type.

[0163] Similarly, a second gear train is driven in rotation by a moving element of the second secondary actuator 8b of the hydraulic cylinder type.

[0164] The first and second gear trains are mechanically linked together, so that one of the gears in the first gear train is rotationally indexed with one of the gears in the second gear train so that they necessarily rotate together.

[0165] Rotational indexing between the gears of the first and second gear trains can be achieved via one or more rotating shafts and possibly via one or more right-angle cardan shafts which transmit the rotational motion from one gear train to the other gear train.

[0166] Thus, even though the cylinders are hydraulically controlled by the hydraulic distributor 70 of the main actuator 7, the mechanical synchronization mechanism 320 ensures that these cylinders move together with a constant ratio of motion throughout this movement. Therefore, the moving parts 4a, 4b necessarily move together because the mechanical synchronization mechanism 320 prevents any variation in the ratio of displacement between the moving elements 8a1, 8b1 of the hydraulic cylinders.

[0167] The hydraulic circuit 330 in Figure 5 includes a high-pressure supply and a low-pressure supply.

[0168] An ICU (Isolation Control Unit) hydraulic isolation valve is arranged between high and low pressure supplies to selectively supply or isolate the part of the hydraulic circuit 330 allowing the hydraulic supply of the main actuator 7 (here integrated into the DCU) and consequently the hydraulic supply of the secondary actuators 8a, 8b which are supplied by the main actuator.

[0169] When the ICU valve is open and the DCU is distributing the fluid, then the various hydraulic lines supplying the secondary actuators 8a, 8b are supplied with pressurized hydraulic fluid to move the doors 4a, 4b.

[0170] Each secondary actuator 8a, 8b comprises an extension chamber and a retraction chamber.

[0171] The extension chambers are supplied together (via circuit 315) with pressurized fluid delivered by the hydraulic distributor 70 and the cylinder retraction chambers are put together with the return fluid together (via circuit 319) to control a simultaneous deployment of the two doors 4a, 4b.

[0172] The retraction chambers are supplied together with pressurized fluid (via circuit 319) delivered by the hydraulic distributor 70 and the extension chambers of the cylinders 8a, 8b are put together at the return of fluid (via circuit 315) to control a simultaneous movement of the two doors 4a, 4b to their over-retracted positions.

[0173] We will now present the operation of the actuation system according to the invention.

[0174] In flight configuration, each moving element of each secondary actuator 8a, 8b is disposed between its extreme positions which are the first and second extreme positions of the moving element and the moving parts 4a, 4b of the thrust reverser are then in their respective retracted positions.

[0175] In this case, in flight configuration each moving element 8al, 8bl of a given secondary actuator 8a, 8b is closer to a first of said extreme positions, called the extreme retraction position of the secondary actuator than to a second of said extreme positions called the extreme extension position of the secondary actuator.

[0176] As in flight configuration, the moving elements 8al, 8bl of the secondary actuators 8a, 8b are between their extreme configurations and the moving parts of the thrust reverser are in their retracted positions, to switch to thrust reverser configuration the control unit Cl commands the movement of the moving elements of the different secondary actuators 8a, 8b to force the movement of the moving parts 4a, 4b of the thrust reverser from their respective retracted positions to their over-retracted positions which has the effect of relieving the mechanical stresses supported by the hooks lOal, 10a2, lObl, 10b2 and thus facilitate their actuation from their locking positions to their release positions under the effect of the locking actuators 11a, 11b.The control unit Cl is configured to control the main actuator 7 and each locking actuator lia, 11b so that the transition from the flight configuration to the thrust reversal configuration is made: - by moving the moving parts 4a, 4b first from their retracted positions to their over-retracted positions; then.

[0177] - by moving the hooks lOal, 10a2 from their locking positions to their release positions; and finally - by moving the moving parts 4a, 4b from their respective over-retracted positions to their respective deployed positions.

[0178] Thus, the hooks move from their locking positions to their release positions while the moving parts 4a, 4b of the thrust reverser have been moved to the over-retracted positions, i.e. after reducing / eliminating the forces exerted by the moving parts 4a, 4b on the hooks lOal, 10a2.

[0179] It should be noted that compressible seals are preferably placed between each moving part and a frame of the reactor through which part of the flow generated by the reactor passes when the moving part 4a, 4b is in the deployed position. These seals are arranged to provide a seal between the moving parts in their retracted positions and the frames. Thus, the compressible seals provide a seal between the frames and the moving parts in the retracted position to prevent the passage of flow through the frames and thereby maximize the thrust of the reactor towards the rear of the reactor. In this embodiment, the moving part 4a, 4b can be a sliding door or a door pivoting relative to the frame.In summary, when switching from flight configuration to thrust reversal configuration, the control unit Cl initially forces the moving parts of the secondary actuators to their extreme over-retracted positions. This compresses the seals and limits the mechanical forces transmitted between the moving parts and the hooks, which remain in their locked positions. This then allows the hooks to move to their respective release positions. The locking actuators lia, 11b are controlled to induce the movement of the hooks.

[0180] In the embodiments of figures 3 and 4, these controls of the locking actuators lia, 11b are all electrical.

[0181] In the electrohydraulic embodiment of Figure 5, one of the locking actuators lia is hydraulically controlled (here the hydraulic control is via the DCU) while the other of the locking actuators 11b (EHPL) is controlled both hydraulically and electrically.

[0182] Finally, in a third step, the movement of the moving elements is carried out towards the other of their extreme positions in order to move the moving parts 4a, 4b towards their respective deployed positions where they allow a reversal of thrust of the reactor (a part of the flux Fr being able to pass through the frame freed from the presence of the moving part).

[0183] In thrust reversal configuration, each moving element of each secondary actuator 8a, 8b is disposed in the second of said extreme positions which corresponds to it (in this case a second extreme position is an extreme extension position of the secondary actuator).

[0184] The transition of the actuation system from the thrust reversal configuration to the flight configuration is done via a command delivered by the control unit Cl such that the main actuator 7 moves the secondary actuators 8a, 8b to force the moving parts 4a, 4b from their respective deployed positions to their respective over-retracted positions while maintaining the hooks of the pairs in their respective release positions, then once the moving parts are in their retracted position, the control unit Cl delivers a command to the locking actuator so that the hooks are moved into their locking positions.

[0185] Once the hooks are in the locked position and the moving parts are retracted, the control unit Cl sends a command to the main actuator 7 so that the secondary actuators move the moving parts to their retracted positions where the moving parts are locked by the hooks in the locked position. The actuation system is then in its flight configuration.

[0186] In all embodiments of the actuation system 6 according to the invention, each of the sensors used to measure primary actuator positions and / or secondary actuators and / or locking actuator and / or hook position and / or moving part position 4a, 4b and / or mechanical connection state between a given hook and a part subjected to a moving part 4a, 4b is functionally connected to a control unit Cl of the actuation system 6 to enable it to collect current position information of each of these elements.

[0187] Returning to the particular case illustrated in Figure 5, where the first actuator 7 is a hydraulically controlled system named "DCU" for "Direction Control Unit", the control unit Cl is represented here in a remote manner with respect to the hydraulic part noted "DCU".

[0188] With reference to the hydraulic embodiment illustrated in Figure 5, the secondary actuators 8a, 8b are here linear hydraulic cylinders but they could be hydraulic cylinders of another type.

[0189] The control unit Cl is here an electronic computer arranged to control the main actuator 7, noted "DCU", which is of the hydraulic type, in order to move the secondary actuators 8a, 8b and thus move the moving parts 4a, 4b.

[0190] Still on figure 5, the first locking actuator lia is noted "HPL" for "Hydraulic Primary Lock", that is, hydraulic locking actuator because it is hydraulically controlled via a part of the hydraulic circuit of the main actuator 7 here noted "DCU" under the effect of a command generated by the control unit Cl.

[0191] Of course, the invention is not limited to the embodiments described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0192] The term "main actuator" refers to an object that transforms the energy supplied to it into a physical phenomenon that performs work, modifies the behavior, or changes the state of a system. For example, the main actuator can, using an energy source which, according to the embodiment of the invention, be electrical and / or hydraulic and / or mechanical energy, actuate the transmission mechanism that simultaneously moves all the moving parts of the secondary actuators.

[0193] The thrust reverser is not necessarily a gated thrust reverser. It could, for example, be a grid-type thrust reverser. In this case, the moving parts of the thrust reverser are covers.

[0194] The number of moving parts can be arbitrary, as can the number of secondary actuators.

[0195] The various sensors mentioned here could be different types of sensors. For example, the hook presence sensors could be force sensors, optical sensors, or electrical continuity sensors.

[0196] Furthermore, the aircraft thrust reverser actuation system according to the invention is compatible with multiple aircraft configurations, such as thrust reversers of wing-mounted engines (twin-engine or four-engine or other) and / or on an engine mounted on the fuselage (possibly integrated into the fuselage) and / or on an engine mounted at the rear of the aircraft, possibly integrated into the tail assembly.

Claims

DEMANDS 1. Actuation system (6), arranged to actuate at least one pair of moving parts (4a, 4b) of a thrust reverser (1) of an aircraft (0), comprising: - a main actuator (7); - secondary actuators (8a, 8b), each comprising a moving element (8al, 8bl) between extreme positions, characterized in that each moving element (8al, 8bl) is connected to a single corresponding moving part (4a, 4b) to move it between a fully retracted position and a fully extended position as a function of the displacement of the moving element (8al, 8bl) between its extreme positions; the actuation system also comprising: - a transmission mechanism (9) connected on the one hand to the main actuator (7) which includes an electric motor (7a) for driving the transmission mechanism (9) and on the other hand to the secondary actuators, the transmission mechanism (9) being configured to, under the effect of the main actuator, simultaneously drive the movement of the moving elements (8a1, 8b1) of the secondary actuators (8a, 8b) between their extreme positions and to simultaneously move the moving parts (4a, 4b) towards their respective over-retracted positions or towards their respective deployed positions, the actuation system (6) also includes a locking mechanism (10) comprising a first pair of hooks (10a1, 10a2), each pivotally mounted between a locking position and a release position, and a first locking actuator (1a1) for simultaneously moving each of the hooks (10a1,10a2) of the first pair of hooks from the locking position to the release position, the, actuation system (6) selectively adopting: - a flight configuration in which each of said moving parts (4a, 4b) is in a retracted position situated between the over-retracted position and the deployed position, the hooks of the first pair of hooks (10a1, 10a2) each being in a locked position such that each given hook of the first pair of hooks (10a1, 10a2) prevents the movement of one of said moving parts (4a, 4b) corresponding to it from the retracted position to the deployed position; and - a thrust reversal configuration in which each of said moving parts (4a, 4b) is in the deployed position; and the transmission mechanism (9) being further arranged to oppose the movement of each of the moving elements (8al, 8bl) as soon as at least one of the hooks (10al, 10a2) in the locked position prohibits said movement of the corresponding moving part (4a, 4b) from the retracted position to the deployed position and in which each secondary actuator (8a, 8b) is mechanically connected to the main actuator (7) via the transmission mechanism (9) so that all the moving elements (8al, 8bl) of the secondary actuators are driven and moved together between their over-retracted and deployed positions by said electric motor (7a) of the main actuator (7).

2. Actuation system (6) according to claim 1, wherein the transmission mechanism (9) is arranged to simultaneously position the moving parts (4a, 4b) in their respective over-retracted positions and to simultaneously position the moving parts (4a, 4b) in their respective deployed positions.

3. Actuation system (6) according to any one of claims 1 or 2, wherein said locking mechanism (10) comprises a second pair of hooks (10b1, 10b2), each pivotally mounted between a locking position and a release position, and a second locking actuator (11b) for simultaneously moving each of the hooks of the second pair of hooks (10b1, 10b2) from its locking position to its release position, in said flight configuration the hooks of the second pair of hooks (10b1, 10b2) each being in the locking position so that each given hook of the second pair of hooks prevents the movement of one of said moving parts (4a, 4b) corresponding to it from the retracted position to the deployed position.

4. Actuation system (6) according to any one of claims 1 to 3, wherein the transmission mechanism (9) comprises, for each secondary actuator (8a, 8b), a separate transmission member (9a, 9b), each secondary actuator (8a, 8b) being connected to the main actuator (7) by a single one of said transmission members (9a, 9b) corresponding to it.

5. An actuation system according to any one of claims 1 to 4, wherein said secondary actuators (8a, 8b) comprise a first secondary actuator (8a) and a second secondary actuator (8b), the transmission mechanism (9) comprising a first transmission member (19a) connecting the primary actuator (7) to the second secondary actuator (8b), and a second member transmission (19b) linking the second secondary actuator (8b) to the first secondary actuator (8a), the moving element (8al) of the first secondary actuator (8a) being moved by the main actuator (7) by transmission of drive forces via the first transmission member (19a) and via the second transmission member (19b).

6. An actuation system according to any one of claims 1 to 5, wherein the actuation system comprises a control unit (Cl) configured to control the main actuator (7) and each locking actuator (11a, 11b), the control unit (Cl) being arranged to control the transition from the flight configuration to the thrust reversal configuration by successively controlling: - to the main actuator (7) to move the moving parts (4a, 4b) from their retracted positions to their over-retracted positions; then - to each locking actuator (1a1a, 11b) to move each of the hooks (10a1a, 10a2) from its locking position to its release position; then - to the main actuator (7) to move the moving parts (4a, 4b) from their respective over-retracted positions to their respective deployed positions while maintaining each of the hooks (10a1, 10a2) in the release position.

7. Thrust reverser (1) comprising the actuation system (6) according to any one of claims 1 to 6 and said pair of moving parts, the actuation system being connected to the moving parts to move them between their retracted and extended positions, the moving parts being preferentially doors.

8. Nacelle (2) of turbojet (3) comprising a thrust reverser (1) according to claim 7.

9. Nacelle (2) of turbojet (3) according to claim 8, containing a rotary turbine (T) of the reactor, the transmission mechanism (9) extending at least in part into a peripheral annular zone of the reactor which surrounds said rotary turbine (T) of the reactor, one of the moving parts (4a) of the pair of moving parts being located on a first side of the turbine (T) and the other of the moving parts (4b) of the pair of moving parts being located on a second side of the turbine (T) which is opposite said first side, at least one of the secondary actuators (8a) being disposed on the first side of the turbine while the other of said secondary actuators (8b) is disposed on the second side of the turbine (T), in said peripheral annular zone of the reactor.

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