EP2841752A1

EP2841752A1 - Actuating device for moving a mobile cap of a thrust reverser

Info

Publication number: EP2841752A1
Application number: EP13719783.6A
Authority: EP
Inventors: Mickael WERQUIN; David CHARRIER; Oleg GOMOLKO; Pascal OMNES
Original assignee: Sagem Defense Securite SA
Current assignee: Safran Electronics and Defense SAS
Priority date: 2012-04-23
Filing date: 2013-04-23
Publication date: 2015-03-04
Also published as: US20150082927A1; US10883446B2; FR2989740A1; WO2013160308A1; US20170138305A1; US9422888B2; FR2989740B1

Abstract

The invention relates to an actuating device (1) for moving a mobile cap of a thrust reverser, comprising: - an actuator comprising a first element (3), such as a screw, and a second element (4), such as a nut, collaborating with the first element in such a way that turning the first element causes the second element to move in a translational movement, - a locking piece (18) rotationally mobile between a locked position in which the locking piece prevents the first element (3) from turning, and an unlocked position in which the locking piece (18) allows the first element (3) to turn, and - an unlocking piece (25) rotationally mobile between an active position in which the unlocking piece (25) urges the locking piece (18) towards the unlocked position and a passive position in which the unlocking piece (25) allows the locking piece (18) to return to the locked position.

Description

ACTUATING DEVICE FOR MOVING

A MOBILE HOOD OF A PUSH INVERTER

FIELD OF THE INVENTION

The invention relates to an actuating device for moving a movable cowl of a thrust reverser.

STATE OF THE ART

Power plant systems (PPS) generally comprise a nacelle and a turbojet engine attached to a pylon of a wing or to a fuselage of the aircraft. In the case of a turbojet turbofan, the turbojet includes a gas generator (high pressure body or CoHP), a low pressure body (or CoBP), a blower and nozzles. The blower makes it possible to accelerate a secondary air flow circulating in an air duct of the blower, to generate the thrust necessary for the propulsion of the aircraft.

Aircraft propulsion units generally include a thrust reversal (TR) system (Thrust Reverse) for reversing the thrust in the landing phases to improve the braking capability of the aircraft. Such a system comprises a set of movable hoods actuated by a set of associated actuators or TR ("Thrust Reverse") for temporarily blocking the air stream and deflecting the secondary air flow to the outside and towards the outside. the front of the nacelle, thereby generating a counter-thrust which is added to the braking of the wheels.

In the case of a thrust reverser system called "doors", the platform is equipped with movable covers (called "doors") which pivot relative to the structure of the platform between a retracted position in which they allow a circulation of the secondary flow in the vein of air to the nozzle and an extended position in which the shutters obstruct the air flow and reorient the air flow to the outside and towards the front of the nacelle.

In the case of a "grids" or "cascade" thrust reversal system, the nacelle is equipped with movable cowlings that slide by relative to the structure of the nacelle along rails between a retracted position in which they allow circulation of the secondary flow in the airstream and towards the nozzle and an extended position in which they discover deflection vanes arranged in the thickness of the nacelle and obstruct the air stream through flaps whose actuation is linked to the movement of the covers.

In general, in either case, the movable covers are actuated by a set of dedicated actuators. Mechanical synchronization of the movement of the actuators is provided by a synchronization system comprising flexible shafts for mechanically connecting the actuators to each other.

In addition, the thrust reversal systems necessarily include several locking devices to prevent inadvertent deployment of the hoods in phase of flight. Among the locking devices fitted to the thrust reversal systems, certain locking systems called "primary" or PLS ("Primary Lock System") act on the flexible shaft to lock the flexible shaft in rotation.

US 6,786,039 discloses a thrust reverser operating system comprising a driven actuator moving between a retracted configuration and an expanded configuration through a drive shaft connected to a flexible shaft. The system includes a locking device that can be controlled to engage or disengage the drive shaft to prevent or allow rotation of the drive shaft. The system further includes a lock inhibitor for holding the latch in the disengaged position until the actuator is in a retracted configuration.

The locking device comprises a movable locking pin in translation, a spring for biasing the rod towards the engaged position and an electromagnet which can be activated to bias the rod towards the disengaged position.

Such a locking device must be designed to operate under significant dynamic loads and despite shocks that may occur produce during the phases of flight and evolution on the ground. In particular, the device must work in case of loss of a fan blade Fan Blade Out that can cause accelerations up to 200G. The locking device must also be insensitive to other sources of excitation (unbalance, rolling shocks, etc.).

Therefore, in locking devices, it is generally necessary to provide a spring having a high stiffness to ensure that the locking rod is not disengaged in case of impact. This has the consequence that it is also necessary to provide a solenoid to generate a large unlocking force to overcome the force exerted by the spring and disengage the locking rod.

It follows that the locking device necessarily has a large footprint because of the large dimensions of the spring and the electromagnet which are provided to prevent inadvertent unlocking.

SUMMARY OF THE INVENTION

An object of the invention is to provide an actuating device which has a small footprint.

This problem is solved in the context of the present invention by means of an actuating device for moving a movable cowl of a thrust reverser, comprising:

an actuator comprising a first element and a second element movably mounted in translation relative to the first element, one of the first element and the second element being a screw, and the other being a nut adapted to cooperate with the screw, so that a rotation of the first element relative to the second element causes a translation of the second element relative to the first element,

a locking device comprising a locking piece movable in rotation between a locked position in which the locking piece prevents the rotation of the first element and a position unlocked in which the locking piece allows rotation of the first member, and

an unlocking device comprising an unlocking part movable in rotation between an active position in which the unlocking piece biases the locking piece towards the unlocked position and a passive position in which the unlocking piece allows a return of the locking piece; in the locked position, and a own drive member to rotate the unlocking part so that the unlocking part moves the locking piece to the unlocked position.

As the locking piece and the unlocking piece are movable in rotation (and not in translation), the unlocking device can be designed so that the locking piece and the unlocking part are very insensitive to sudden accelerations that can exert on the actuating device in case of shock. In particular, the unlocking device may be designed so that the unlocking part is rotatable about an axis of rotation passing through the center of gravity of the unlocking part.

It is thus possible to design a device incorporating a return member of reduced dimensions and mass, and a drive member of reduced dimensions and mass.

The device can furthermore have the following characteristics:

the locking device comprises a tooth mounted to rotate with the first element, the locking piece being clean, in the locked position, to come into engagement with the tooth to prevent rotation of the first element,

the locking piece comprises a clean pawl for engaging the tooth in the locked position,

- The locking device comprises a roller carried by the unlocking part, adapted to maintain the pawl in engagement with the tooth when the pawl is in the locked position, the unlocking piece comprises a pin which, when the unlocking piece is rotated, biases the pawl to pivot the pawl towards the unlocked position,

the locking piece comprises a latch having a convex portion and a concave portion adapted to be selectively positioned facing the tooth, the convex portion being adapted to interfere with the tooth when the convex portion is facing the tooth to prevent rotation; the first element, and the concave portion being adapted to allow rotation of the first element when the concave portion is opposite the tooth,

the tooth is asymmetric so that, in the locked position, the locking piece prevents rotation of the first element in a first direction and allows rotation of the first element in a second direction, opposite to the first direction,

the locking piece is able to mesh with the unlocking piece so that the rotation of the unlocking part controls the rotation of the locking piece;

the drive member comprises a rotary electromagnet,

the unlocking device comprises a return spring capable of urging the unlocking part towards the passive position,

the unlocking device comprises an abutment and a retaining piece integral in rotation with the unlocking piece and movable in translation relative to the unlocking part between a retaining position in which the rotation of the retaining piece is limited by the stop and a release position in which the retaining piece is free to rotate,

the actuating device comprises a return member adapted to urge the retaining piece towards the retaining position,

the actuating device comprises a rod movable in translation relative to the first element and being able to be urged by the second element to move the retaining piece towards the release position, the movable rod extends at least partly inside the first element,

the actuating device further comprises a manual unlocking device for urging the retaining piece in rotation in order to bring the unlocking piece into the active position, without activating the driving member;

- the first element is the screw and the second element is the nut.

PRESENTATION OF THE DRAWINGS

Other features and advantages will become apparent from the description which follows, which is purely illustrative and nonlimiting, and should be read with reference to the appended figures among which:

FIG. 1 schematically represents, in longitudinal section, a device according to a first embodiment of the invention,

FIG. 2 schematically represents, in perspective, a part of the device of FIG. 1,

FIG. 3 schematically shows, in a rear view, the locking device of the device of FIG. 1,

FIG. 4 schematically shows, in a rear view, the device for unlocking the device of FIG. 1,

FIG. 5 is a detailed view schematically showing the shape of a locking piece,

FIGS. 6A to 12C schematically represent operating steps of the device according to the first embodiment,

FIG. 13 schematically represents, in perspective, a part of an actuating device according to a second embodiment of the invention,

FIGS. 14A and 14B show schematically in a rear view the locking device of the device of FIG. 1, in the unlocked position and in the locked position, respectively; - Figures 15A and 15B show schematically in cross section, the device for unlocking the device of Figure 1, respectively in the passive position and in the active position. DETAILED DESCRIPTION OF AN EMBODIMENT

In Figure 1, the device 1 shown comprises a housing 2, a screw 3 extending from the housing 2 and a nut 4.

The screw 3 has a body 10 of generally elongate cylindrical shape and is rotatably mounted relative to the casing 2 of the device about an axis of rotation X corresponding to the longitudinal axis of the screw 3 and also corresponding to an axis of deployment of the actuator.

The screw 3 comprises a first end 5 (or receiving end) intended to receive a driving torque and a second end 6 (or free end) extending away from the first end 5. The actuator 1 comprises a conical wheel input 7 mounted integral with the screw 3 at the first end 5 of the screw. The conical input wheel 7 meshes with a gear part 8 of a drive shaft 9, so as to transmit a rotational movement of the drive shaft 9 to the screw 3.

The nut 4 extends around the body 10 of the screw 3 and is intended to be fixed to an actuator tube 55 having an end 56 connected to a moving component of the thrust reverser (a movable cover for example) through a ball joint 57 with anti-rotation stops.

The nut 4 is mounted mobile in translation relative to the screw 3 along the longitudinal axis X of the screw 3 to move the actuator tube between two extreme positions respectively corresponding to a retracted configuration and to an expanded configuration of the actuator.

The body 10 of the screw has a cylindrical outer surface 1 1 in which is formed a helical groove 12. The nut 4 has a cylindrical inner surface 13 in which is formed a helical groove 14. The screw 3 and the nut 4 cooperate between them through the helical grooves 12 and 14 in which are housed balls 15 of so that a rotation of the screw 3 relative to the housing 2 causes a translation of the nut 4 relative to the screw 3 in the direction X.

The device 1 also comprises a drive shaft 9 having a first end 15 and a second end 16. The first end 15 is shaped to be connected to a first drive shaft of a thrust reverser or flexible shaft 58, the first motor shaft being connected to a drive motor arranged at a distance from the actuating device. The second end 16 comprises a conical wheel 8 arranged to mesh with the conical input wheel 7 of the screw 3 in order to drive the screw 3 in rotation.

When the motor is activated, the rotation of the screw 3 concomitantly causes a translation of the nut 4 between a first extreme position (corresponding to a retracted configuration of the device) in which the moving component of the thrust reverser is retracted and a second extreme position (corresponding to an expanded configuration of the device) in which the movable component of the thrust reverser is deployed thus allowing to deflect the flow of air towards the front of the nacelle.

The device 1 also comprises a locking device 17 visible in Figure 3 to lock the screw 3 in rotation when the actuator is in the retracted configuration, and thus prevent unintentional deployment of the actuator, especially in the flight phase.

The locking device 17 comprises a first locking piece 18 in the form of a pawl 46 rotatably mounted relative to the casing 2, and a second locking piece 19 having two teeth 20 and 21, the second locking piece 19 being mounted secured to the screw 3. The pawl 46 is rotatable between a locked position (illustrated in Figure 3) in which the pawl 46 engages with one of the teeth 21, thereby preventing rotation of the screw 3, and an unlocked position (illustrated for example in Figure 7) in which the pawl 46 is spaced from the tooth 21, thus allowing a rotation of the screw 3.

The locking device 17 further comprises a return spring 22 (such as a torsion spring) capable of biasing the pawl 46 into position. rotation to the locked position to maintain the pawl 46 in engagement with the tooth 21.

Furthermore, the device 1 comprises an unlocking device 23 comprising a drive member 24 and an unlocking part 25.

The unlocking part 25 is rotatably mounted relative to the casing 2 by means of a ball bearing 26 mounted between the casing 2 and the unlocking part 25. The unlocking part 25 is rotatable relative to the casing 2 around an axis of rotation coincides with the axis of rotation X of the screw 3, between an active position in which the unlocking part 25 biases the locking piece 18 to the unlocked position and a passive position in which the piece of unlocking 25 allows a return of the locking piece 18 in the locked position.

The unlocking part 25 has a first cylindrical portion 27 of small diameter and a second cylindrical portion 28 of large diameter.

The unlocking part 25 further comprises a pin 29 visible in Figure 3, arranged at the periphery of the cylindrical portion 28 of large diameter. The pin 29 is able to urge the pawl 46 by pivoting it to the unlocked position when the unlocking part 25 is rotated in a first direction (shown in Figure 2 by the arrow A).

The unlocking part 25 also comprises a roller 30 carried by the unlocking piece 25, also arranged at the periphery of the large-diameter portion 28. The roller 30 is able to press the pawl 46 to hold the pawl 46 in place. engagement with the tooth 21 when the pawl 46 is in the locked position and the unlocking part 25 is in the passive position.

The drive member 24 comprises an electromagnet 31 arranged around the small diameter portion 27 of the unlocking member 25. When activated, the electromagnet 31 rotates the workpiece. unlocking 25 in the first direction of rotation (arrow A) to the active position to unlock the pawl 46.

The unlocking device 23 also comprises a return spring 32 capable of urging the unlocking part 25 in a second direction of rotation (represented by the arrow B), opposite to the first direction of rotation towards the passive position, in order to bring back the ratchet 46 in the locked position when the electromagnet 24 is not activated.

Furthermore, the actuating device 1 comprises a retaining device 33 for holding the pawl 46 in the unlocked position as long as the actuator is not in the retracted configuration, even when the electromagnet 24 is not activated.

The retaining device 33 comprises a retaining piece 34 and a stop 35 adapted to cooperate with the retaining piece 34 to selectively prevent or allow rotation of the unlocking part 25.

The retaining piece 34 comprises a pusher 36 extending inside the unlocking part 25 in the direction X, and a retaining finger 37 fixed to one end of the pusher 36 and extending in a radial direction relative to at the pusher 36. More specifically, the pusher 36 extends inside the small diameter portion 27 of the unlocking part 25. The pusher 36 is integral in rotation with the unlocking part 25, but is movable in translation relative to the unlocking part 25, in the direction X. For this purpose, the outer surface 38 of the pusher 36 and the inner surface 39 of the unlocking part 25 are provided with longitudinal grooves, the grooves of the rod 38 being adapted to cooperate with the grooves of the unlocking part 25 to allow a translation of the rod 38 relative to the unlocking part 25 while prohibiting a rotation of the pusher 36 relative the unlocking part 25.

The retaining piece 34 is movable in translation relative to the unlocking part 25 between a retaining position (illustrated for example in FIG. 12A) in which the rotation of the retaining piece 34 is limited by the stop 35 and a position of liberation (illustrated by example in Figure 1) in which the retaining piece 34 is out of reach of the stop 35 and is therefore free to rotate.

The actuating device 1 also comprises a rod 40 movable in translation relative to the screw 3, the movable rod 40 extending at least partly inside the screw 3. The movable rod 40 is able to be requested in translation by the nut 4 when the nut 4 reaches the first extreme position corresponding to the retracted configuration of the device 1.

The retaining piece 34 is adapted to be urged by the movable rod 40 to move the retaining piece 34 in a first direction (shown in Figure 1 by the arrow C) to the release position.

Furthermore, the retaining device 33 comprises a return spring 41 able to urge the retaining piece 34 in a second direction (represented by the arrow D), opposite to the first direction, to return the retaining piece 34 to the position of retained when the movable rod 40 no longer solicits the retaining piece 34.

The stop 35 is fixed to the housing 2 and comprises a pin 42 projecting from the housing 2 in a direction substantially parallel to the direction X. The pin 42 is adapted to cooperate with the finger 37 to prevent rotation of the retaining piece 34 (and therefore of the unlocking part 25) relative to the housing 2. More specifically, when the retaining piece 34 is in the retaining position, the finger 37 comes into radial abutment against the pin 42 under the action of the spring 32, the pin 42 preventing the rotation of the retaining piece 34.

As can be seen in FIG. 4, the actuating device 1 further comprises a manual unlocking device 54 for rotating the retaining piece 34 in order to bring the unlocking part into the active position, in the case of assembly or maintenance operations of the actuating device. Specifically, the manual unlocking device 54 includes a manually movable pusher for biasing the finger 37 to pivot the retainer 34, and thereby the unlocking member 25 to the active position. FIG. 5 is a detail view schematically showing the shape of the pawl 46.

As shown in Figure 5, the pawl 46 has a second recessed portion 45 adapted to come into contact with the unlocking pin 29 when the unlocking part 25 urges the pawl 46 to the unlocked position. The shape of the second recessed portion 45 reduces the friction force due to the support of the pawl 46 on the pin 29 at the end of unlocking and when holding the pawl 46 in the unlocked position.

FIGS. 7A to 12C schematically represent operating steps of the actuating device 1.

The actuating device is initially in the retracted configuration (FIG. 6A), the nut 4 being in the first extreme position.

As shown in Figure 6B, the pawl 46 is in the locked position. The free end 43 of the pawl is in abutment against the tooth 21, which prevents any rotation of the screw 3. In addition, the roller 30 holds the pawl 46 in the locked position. In this configuration, the deployment of the actuating device 1 is not possible.

Moreover, as shown in FIGS. 6A and 6C, the retaining piece 34 is in the release position, the finger 37 of the retaining piece being out of reach of the stop 35.

When the pilot controls the deployment of the thrust reverser, a control system triggers the supply of the electromagnet 31 (FIG. 7A). The electromagnet 31 then applies a torque to the unlocking part 25, which has the effect of rotating the unlocking part 25 around the axis X, in the first direction indicated by the arrow A (FIGS. 7B and 7C). .

The rotation of the unlocking part 25 has the effect, at first, to release the roller 30 from the pawl 46 (FIG. 9B) and simultaneously to rotate the finger 37.

While the unlocking member 25 is rotated by the electromagnet 31 (Figure 8A), the pin 29 is, in a second step, bias the pawl 46 (Figure 8B) to separate the pawl 46 of the tooth 21. More specifically, the pin 29 comes to urge the pawl 46 once the roller 30 is no longer in contact with the pawl 46. Furthermore, the finger 37 pivots (FIG. 8C) and passes beyond the abutment 35.

Once the pawl 46 is in the unlocked position (FIGS. 9A and 9B), the actuating device 1 can be deployed. Indeed, the pawl 46 allows a rotation of the screw 3. The screw 3 is rotated so that the nut 4 is translated along the screw 3 in the X direction away from the first extreme position. Moving away from the first extreme position, the nut 4 stops urging the movable rod 40 and therefore the retaining piece 34. The retaining piece 34 is displaced in translation along the X axis in the second direction D under the action of the return spring 41. This has the effect that the finger 37 is positioned behind the stop 35 (FIGS. 9A and 9C), the stop 35 preventing the rotation of the retaining piece 34 (and consequently of the unlocking piece 25) in the second direction ( arrow B).

From this moment, the electromagnet 31 can be deactivated, without the pawl 46 returning to the locked position. Indeed, the retaining piece 34 holds the unlocking part 25 in the active position, that is to say a position in which the unlocking part 25 holds the pawl 46 in the unlocked position.

This has the consequence that the actuating device 1 can not be locked until the nut 4 has returned to the first extreme position, that is to say as long as the actuating device is not returned in retracted configuration.

When the thrust reverser is retracted, the screw 3 is rotated so that the nut 4 is translated along the screw 3 in the direction X to the first extreme position. Approaching the first extreme position, the nut 4 comes to urge the movable rod 40 and therefore the retaining piece 34. The retaining piece 34 is displaced in translation along the X axis in the first direction C (FIG. 10A) under the effect of the thrust of the rod 40. This has the effect of moving the finger 37 out of reach of the stop 35. Once the finger 37 is out of reach of the stop 35 (Figures 1 1A and 9C), the stop 35 no longer prevents the rotation of the retaining piece 34 (and therefore the unlocking part 25). The retaining piece 34 (and consequently the unlocking part 25) is rotated in the second direction (arrow B) under the effect of the return spring 32 (Figure 1 1 B). The unlocking part 25 releases the pawl 46 which pivots towards the locked position under the action of the return spring 22.

The rotation of the unlocking part 25 also has the effect of bringing the roller 30 into contact with the pawl 46 (FIG. 12B) and simultaneously of rotating the finger 37. The free end of the pawl 46 abuts against the tooth 21 and the roller 30 bears on the ratchet

46 to maintain the pawl 46 in engagement with the tooth 21.

Thus, the complete retraction of the actuating device causes an automatic return of the locking device in the locked position. Once the locking device is in the locked position, the locking device can no longer be unlocked unless the pilot again controls the deployment of the thrust reverser, which triggers the activation of the electromagnet.

Figure 13 shows schematically an actuating device 1 according to a second embodiment of the invention.

The actuating device 1 according to the second embodiment is identical to the device of the first embodiment, with the exception that the locking piece 18 is a cylindrical lock.

47 rotatably mounted relative to the housing 2 about an axis X 'parallel to the axis X.

The cylindrical lock 47 comprises on the one hand a locking portion 48 and on the other hand a driving portion 49.

As shown in Figures 16A and 16B, the locking portion 48 has a half moon shape. More specifically, the locking portion 48 comprises a convex portion 50 engagement and a concave portion 51 (or substantially flat) disengagement adapted to be selectively positioned facing the tooth 21 when the latch 47 is rotated.

When the latch 47 is in the unlocked position (FIG. 14A), the concave portion 51 is positioned facing the tooth 21 so as to allow the rotation of the second locking piece 19 (and consequently of the screw). When the latch 47 is in the locked position (FIG. 14B), the convex portion 50 is positioned facing the tooth 21 so as to interfere with the tooth 21 and thus prevent rotation of the screw 3.

As illustrated in FIGS. 15A and 15B, the drive portion 49 comprises a toothed sector 52. The unlocking part 25 also comprises a toothed sector 53 arranged to mesh with the toothed sector 52 of the lock 47. Thus, the rotation latch 47 is controlled by the rotation of the unlocking part 25.

The rotation of the unlocking part 25 in the first direction of rotation (arrow A) has the effect of pivoting the latch 47 to the unlocked position (illustrated in Figure 15B).

Conversely, the rotation of the unlocking part 25 in the second direction (arrow B), opposite to the first direction, has the effect of pivoting the latch 47 to the locked position (illustrated in Figure 15A).

The operation of the actuating device 1 according to the second embodiment is identical to the operation of the actuating device 1 according to the first embodiment.

Claims

1. An actuating device (1) for moving a movable cowl of a thrust reverser, comprising:

an actuator comprising a first element (3) and a second element (4) mounted mobile in translation relative to the first element, one of the first element and the second element being a screw, and the other being a nut adapted to cooperating with the screw, so that a rotation of the first element (3) relative to the second element (4) causes a translation of the second element (4) with respect to the first element (3),

a locking device (17) comprising a locking piece (18) rotatable between a locked position in which the locking piece (18) prevents rotation of the first member (3), and an unlocked position in which the piece locking mechanism (18) allows rotation of the first element (3), and

- an unlocking device (23) comprising an unlocking part (25) movable in rotation between an active position in which the unlocking part (25) biases the locking piece (18) towards the unlocked position and a passive position in which the unlocking part (25) allows a return of the locking piece (18) in the locked position, and a drive member (24) capable of rotating the unlocking piece (25) so that the unlocking piece ( 25) moves the locking piece (18) to the unlocked position.

2. Device according to claim 1, wherein the locking device (17) comprises a tooth (20, 21) mounted to rotate with the first member (3), the locking piece (18) being clean, in the locked position, to come into engagement with the tooth (20, 21) to prevent rotation of the first member (3).

3. Device according to claim 2, wherein the locking piece (18) comprises a ratchet (46) adapted to come into engagement with the tooth (20, 21) in the locked position.

4. Device according to claim 3, wherein the locking device (17) comprises a roller (30) carried by the unlocking part (25), adapted to maintain the pawl (46) in engagement with the tooth (20, 21). ) when the pawl (46) is in the locked position.

5. Device according to one of claims 3 or 4, wherein the unlocking part (25) comprises a pin (29) which when the unlocking part (25) is rotated urges the pawl (46) to rotate the pawl (46) to the unlocked position.

6. Device according to claim 2, wherein the locking piece (18) comprises a latch (47) having a convex portion (50) and a concave portion (51) adapted to be selectively positioned facing the tooth (20, 21), the convex portion (50) being proper to interfere with the tooth (20, 21) when the convex portion (50) is facing the tooth (20, 21) to prevent rotation of the first member (3), and the concave portion (51) being adapted to allow rotation of the first element (3) when the concave portion (51) is opposite the tooth (20, 21).

7. Device according to one of claims 2 to 6, wherein the tooth (20, 21) is asymmetrical so that in the locked position, the locking piece (25) prohibits a rotation of the first member (3) in a first direction (A) and allows a rotation of the first element (3) in a second direction (B), opposite the first direction.

8. Device according to one of claims 1 to 7, wherein the locking piece (18) is adapted to mesh with the unlocking part (25) so that the rotation of the unlocking part (25) controls the rotation the locking piece (18).

9. Device according to one of claims 1 to 8, wherein the drive member (24) comprises a rotary electromagnet (31).

10. Device according to one of claims 1 to 9, wherein the unlocking device (23) comprises a return spring (32) adapted to urge the unlocking part (25) to the passive position.

1 1. Device according to one of the preceding claims, wherein the unlocking device (23) comprises a stop (35) and a retaining piece (34) integral in rotation with the unlocking part (25) and movable in translation relative to to the unlocking piece (25) between a retaining position in which the rotation of the retaining piece (34) is limited by the stop (35) and a release position in which the retaining piece (34) is free in rotation.

12. Device according to claim 1 1, comprising a return member (41) adapted to bias the retaining piece (34) to the retaining position.

13. Device according to one of claims 1 1 or 12, comprising a rod (40) movable in translation relative to the first member (3) and being adapted to be urged by the second member (4) to move the retaining piece (34) to the release position.

14. Device according to claim 13, wherein the movable rod (40) extends at least partly inside the first element (3).

15. Device according to one of claims 1 1 to 14, further comprising a manual unlocking device (54) for urging in rotation the retaining piece (34) to bring the unlocking part (25) in the active position without activating the drive member (24).

16. Device according to one of the preceding claims, wherein the first element (3) is the screw and the second element (4) is the nut.