WO2022123171A1

WO2022123171A1 - Device for locking an electromechanical actuator provided with means for protecting against seizures or blockages

Info

Publication number: WO2022123171A1
Application number: PCT/FR2021/052230
Authority: WO
Inventors: Daniel Hors
Original assignee: Safran Electronics & Defense Actuation
Priority date: 2020-12-09
Filing date: 2021-12-07
Publication date: 2022-06-16
Also published as: FR3117090A1; FR3117090B1

Abstract

Said device for locking an electromechanical actuator comprises a cylindrical tube (3) which is movable relative to a fixed outer cylinder (2) by the action of drive means, and first releasable means (8) for locking the cylindrical tube in the fixed outer cylinder. It comprises second releasable means (9) for complementary locking of the cylindrical tube (3) which operate independently of the first locking means and are positioned between the drive means and the cylindrical tube, the second releasable locking means (9) comprising an intermediate tube (25) suitable for being driven by the drive means and an assembly of at least one hook (30) engaging in a recess. Said assembly of hooks and the recess are located on the intermediate tube and the cylindrical tube, respectively.

Description

DESCRIPTION

TITLE: Device for locking an electromechanical actuator equipped with means of protection against seizing or jamming

The present invention relates to electromechanical actuators and relates more particularly to the protection of actuators against malfunctions.

The invention relates in particular to an electromechanical actuator provided with means of protection against seizing or jamming, intended to be used in avionics.

In a particularly advantageous application, the invention relates to an electromechanical actuator for an aircraft landing gear.

Claw-locking jacks are already known that can be used for maneuvering and bracing members equipping aircraft landing gear, and locking them in the low position.

Retractable landing gear is usually hydraulically activated by hydraulic pressure.

Landing gear architectures comprising one or more external or internal locks to the hydraulic actuator are known.

These locks can be coupled with one or more indicators to indicate that the gear is in the extended and locked position or in the retracted and locked position.

In particular, claw locking devices have been developed adapted to architectures comprising actuators in direct drive on hydraulic landing gears and supporting all the forces applied to the gears.

However, the system for actuating and locking hydraulic trains has certain drawbacks, such as requiring additional equipment, such as pumps and high pressure circuits. In addition, the system for actuating and locking the landing gear must comply with regulations which impose locking by form complementarity, or “positive”, in the extended position.

Reliability and safety requirements also require obtaining reliable "gear extended and locked" or "gear retracted and locked" information.

Electromechanical actuators thus tend to replace hydraulic actuators.

Reference may be made to document EP 2 149 496 and to document ER 1 756 035 which describes a locking device and an electromechanical actuator for aircraft landing gear, the extended position of which constitutes an automatic locking position.

This device uses a set of hooks which fit into a recess when the gear is in the extended position, a retractable lock locking the hooks in the recess.

Although advantageous in many respects, this locking device is not intended to provide an emergency mode to release the actuator and allow the extension of the train, for example under the effect of gravity, in particular in the event of seizure, when using an electromechanical actuator.

The object of the invention is therefore to propose a locking device for an electromechanical actuator allowing the extension of the actuator in emergency mode in the event of failure of one or more constituent elements of the actuator.

The subject of the invention is therefore a locking device for an electromechanical actuator, comprising a cylindrical tube which is movable relative to a fixed external cylinder, under the action of drive means, and first releasable means for locking the tube cylinder in the fixed outer cylinder.

This device comprises second releasable means for complementary locking of the cylindrical tube operating independently of the first locking means and interposed between the drive means and the cylindrical tube, the second means releasable locking devices comprising an intermediate tube capable of being driven by the motor means and a set of at least one hook engaging in a recess, said set of hooks and the recess being placed one on the intermediate tube and the another on the cylindrical tube.

Thus, when the claws are placed in the cavity, the second locking means ensure the connection between the motor means and the cylindrical tube, during normal operation. In the event of a malfunction, their unlocking allows the actuator to be released.

The second locking means thus constitute an emergency device providing protection against seizures, blockages or other malfunctions, the claws securing the intermediate tube and the outer cylindrical tube in normal operation and disengaging them on demand if necessary, in the event of seizing or failure of the actuator, whatever its position.

When the locking device is used in a landing gear actuator, the gear can then be freely extended, under the action of gravity or manually, even in the event of malfunction of the motor means, the intermediate tube being freed from these last.

According to another characteristic, the second locking means comprise a sliding lock between a locking position of the hooks in the recess and an unlocking position in which the hooks are released from the recess.

Advantageously, a spring urges the lock into the locking position of the hooks.

In one embodiment, the intermediate tube is placed inside the cylindrical tube and comprises a first end provided with a thread cooperating with a threaded rod driven by an actuation motor and an opposite second end fitting into the cylindrical tube.

Advantageously, said set of hooks is fixed to the second end of the intermediate tube and the cylindrical tube internally comprises an axial head comprising a peripheral indentation in which said set of hooks engages.

In another embodiment, said set of hooks is fixed to the first end of the cylindrical tube, the intermediate tube comprising a peripheral cavity in which said set of hooks engages.

For example, the hooks comprise at least one inclined face capable of cooperating with a complementary ramp of the cavity.

In various embodiments, the first locking means comprise a set of at least one hook and an indentation in which said set of hooks engages so as to lock the cylindrical tube in the end-of-travel position, said set of hooks and the cavity being carried one by the outer cylinder and the other by the movable cylindrical tube, and a lock sliding relative to said hook and to the cavity between a position for holding said hooks in the locking position and a position releasing the hooks.

For example, the lock is connected in movement to the intermediate tube.

The invention also has as object and, according to another aspect, an electromechanical actuator comprising a cylindrical tube movable relative to a fixed outer cylinder in which the movable tube is placed, and comprising a locking device as defined above.

Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the indexed drawings on which:

[Fig 1] is a schematic sectional view of an actuator provided with a locking device and an emergency extension device according to a first embodiment of the invention;

[Fig 2] illustrates the actuator of Figure 1 in the extended position and locked in normal operation; [Fig 3] shows the actuator of Figure 1 in the extended position and locked in emergency mode;

[Fig 4] illustrates another embodiment of a locking device according to the invention;

[Fig 5] shows the actuator of Figure 4 in the extended position and locked in normal mode;

[Fig 6] shows the actuator of Figure 4 in the extended and locked position, in emergency mode.

There is shown in Figure 1 a first embodiment of an actuator according to the invention, designated by the general reference numeral 1.

In the exemplary embodiment envisaged, this actuator constitutes a landing gear actuator for an aircraft, the extended position of which constitutes an automatic locking position.

Of course, we do not depart from the scope of the invention when such an actuator is intended to be used in other applications.

This actuator is an electromechanical actuator.

It comprises a fixed outer cylinder 2 and an inner cylindrical tube 3 movable in the fixed outer cylinder 2 between a fully deployed position, which corresponds to an exit position from the train and a retracted position, which corresponds to a retracted position of the train. landing, under the action of motor means 4 comprising a motorized screw 5, for example associated with a motor 6 for actuating the actuator 1, illustrated schematically.

In Figure 1, the cylindrical tube 3 is shown in a retracted position of the landing gear in which the tube 3 is retracted in the fixed outer cylinder.

As can be seen, the outer cylinder 2 is provided with an end cap 7 which is provided with a central passage for the cylindrical tube 3. The actuator 1 is provided with first locking means 8 which act on the tube cylindrical 3 to lock it at the end of its travel, in the exit position. In the embodiment of Figure 1, the first locking means act on the cylindrical tube 3 when the latter is in the fully extended position.

These first locking means 8 are automatically activated when the cylindrical tube comes out.

The actuator is further provided with second locking means 9 which are interposed between the motor means and the cylindrical tube 3.

These second locking means are intended to be unlocked in the event of malfunction of the motor means, in particular in the event of seizure or in the event of a drop in performance of the motor means, to release the actuator and allow the landing gear to be extended manually or under the action of gravity.

They are active by default and ensure the connection between the cylindrical tube 3 and the motor means 4, in the absence of a malfunction.

As regards the first locking means, these comprise a set of claws 10 each provided with a foot, or a common foot, fixed in translation to the outer cylinder 2. The claws

10 are each provided at their free end with an elastic hook

1 1 comprising an elastic arm 12 and an end head 13 comprising an inner face, facing the cylindrical tube 3, bevelled so as to delimit surfaces in proximal 14 and distal 15 ramp.

The elastic arm 12 is here fixed on the cover 7 of the outer cylinder.

Cylindrical tube 3 is provided with an indentation 16 made on the outer peripheral surface of tube 3.

For example, this imprint 16 is an annular imprint. It forms a housing of complementary shape to that of the head 13 of the claws. It is made in the vicinity of the proximal end 17 of the tube 3, through which this tube is inserted into the outer cylinder 2. On the distal side, it is bordered by a ramp 18 for the latching of the end head 13 of the claws and, on the proximal side, a flat cylindrical surface 19.

The actuator is also provided with first means 20 for unlocking the first locking means 8 which comprise a bolt 21 sliding on the cylindrical surface 19 of the proximal end of the cylindrical tube 3, this bolt 21 comprising a cylindrical extension 22.

A spring 23 is interposed between an end shoulder 24 of the proximal end of the tube 3 and the lock 21.

As regards the second locking means, these comprise a cylindrical intermediate tube 25, comprising a proximal end 26 and a distal end 27.

This intermediate tube 25 is placed in the outer cylinder 2 and extends mainly into the cylindrical tube 3.

The proximal end 26 of the intermediate tube 25 comprises a thread 28 which cooperates with the motorized screw 5 and an annular shoulder 20 on which the proximal end 17 of the cylindrical tube 3 rests. Alternatively, the intermediate tube is driven by the screw 5 by a hollow ball screw mechanism.

The distal end 27 of the intermediate tube 25 is provided with a set of end claws 29 similar to the claws 10 of the first locking means.

They each comprise at their free end an elastic hook 30 comprising an elastic arm 31 fixed to the distal end of the intermediate tube 25 and an end head 32 comprising a bevelled radially internal face delimiting two ramped surfaces, proximal 33 and distal 34.

The distal end of the cylindrical tube 3 is internally provided with an axial head 36 provided with an annular indentation 37 which forms a housing of complementary shape to that of the head 32 of the claws.

In normal operation, that is to say in the absence of malfunction of the motor means, the claws fit into the annular cavity 37. Second locking means 38, consisting of a sliding lock, hold the claws in the cavity.

While the first lock 21 is activated and deactivated under the action of the motorized screw 5, the second unlocking means are activated by an external actuator, for example a cable actuator 39, or by any other appropriate means, such as a motor or an electromagnet.

A spring R is interposed between the distal end of the cylindrical tube 3 and the lock 38 to urge the latter into a position for locking the claws in the cavity.

This embodiment operates as follows.

As shown in Figure 2, when the motorized screw 5 is actuated, the intermediate tube 25 is moved in translation. The cylindrical tube 3, which is linked to the intermediate tube 25 under the action of the claws inserted in the cavity 37, is locked by the lock 38 and simultaneously moved in translation to its exit position.

In this position, the first locking means snap into recess 16. The deployed position of the actuator is locked by lock 21.

When the actuator must be retracted, the motorized screw 5 is actuated in the opposite direction. The lock 21 is first unlocked so as to allow the elastic hooks 10 to come out under the action of the distal ramp 15.

When a malfunction appears, such as a seizure, the lock 38 is retracted. When the claws 30 are released from the lock 38, these are spontaneously released from the recess 37 under the action of the ramp or pan 34 and the complementary shape of the recess. The cylindrical tube 3 is then released, allowing the output of the cylindrical tube 3 under the action of gravity or manually.

In the embodiment described with reference to Figures 1 to 3, the second locking means are carried by the distal end of the intermediate tube 25.

Another embodiment of an actuator according to the invention has been presented in FIGS. 4 to 6. In these figures, in which elements identical to those described previously bear the same numerical references, the outer cylinder 2, the cylindrical tube 3, the first locking means, the first unlocking means, the second locking means, the second unlocking means as well as the intermediate tube 25.

In this embodiment, the second locking means comprise a set of claws 30 identical to the claws described above with reference to Figures 1 to 3.

These claws also comprise an elastic hook 31 comprising an elastic arm 32 and an end head 33 comprising a beveled internal face so as to delimit two proximal and distal ramped surfaces, respectively 34 and 35. The bevelled internal face is turned towards the proximal end of the cylindrical tube 3.

The external cylindrical surface of the proximal part of the intermediate tube 25 comprises an indentation 40 which forms a housing of complementary shape to that of the head of the claws.

During normal operation of the actuator, the heads snap into place in the recess of the proximal end of the intermediate tube. The impression 40 is bordered, on the proximal side, by a cylindrical surface 41 and on the distal side by a ratchet ramp 42.

Lock 38 includes a cylindrical extension 43 which covers the claws and holds them in recess 40. A spring 44 urges the lock into this unlocked position.

An external actuator, for example with a cable (not shown), makes it possible to unlock the claws.

Referring to Figures 5 and 6, this second embodiment includes a similar operation to that described above.

Indeed, with reference to Figure 5, in normal operation, the cylindrical tube 3 is locked in translation on the intermediate tube 25. The rotation of the motorized screw 5 causes the simultaneous translational movement of the intermediate tube and of the cylindrical tube 3. At the end of travel, the first locking means are activated.

With reference to FIG. 6, in the event of a malfunction, the second unlocking means are activated so as to separate the cylindrical tube 3 and the intermediate tube 25 in translation, causing the cylindrical tube 3 to be released under the action of gravity, or even manually.

In the embodiments which have just been described, the drawer can be associated with a switch indicating the unlocked state of the second locking device and, therefore, providing an indication that an emergency mode has been implemented,

Furthermore, thanks to the beveled shape of the claws and the corresponding shape of the indentations, when the drawer of the second locking means is moved, the claws are automatically released.

The locking can again be carried out automatically by driving the motorized screw 5 in rotation until the intermediate tube joins the cylindrical tube 3 and the claws 30 snap into the corresponding recess.

The locking device which has just been described, which comprises releasable locking means ensuring a disengageable coupling of the cylindrical tube, makes it possible to release the output rod of the actuator in the event of seizure or in the event of a significant loss of performance of the actuator. ' actuator.

In other words, this device makes it possible to completely free the output rod when manual or emergency operation is necessary without the seizing or a significant loss of efficiency of the actuator being able to have any consequences.

In addition, the locking of the cylindrical tube on the intermediate tube by hook and drawer actuated by a spring allows a reliable and robust automatic locking, the force of the spring being exerted on the drawer being such that the maintenance in position is guaranteed whatever the environmental conditions (vibration, shocks, load factor, etc.) It also has the following advantages:

- low friction after unlocking;

- no risk of failure;

- very high availability of the unlocking device; - very high mechanical resistance of the unlocking device.

Claims

1. Locking device for an electromechanical actuator comprising a cylindrical tube (3) which is movable relative to a fixed outer cylinder (2), under the action of drive means (4) for actuation, and first releasable means (8 ) for locking the cylindrical tube in the fixed outer cylinder, characterized in that it comprises second releasable means (9) for complementary locking of the cylindrical tube (3) operating independently of the first locking means and interposed between the motor means and the cylindrical tube, the second releasable locking means (9) comprising an intermediate tube (25) capable of being driven by the motor means and a set of at least one hook (30) engaging in a recess (37), said set of hooks and the footprint being placed one on the intermediate tube and the other on the cylindrical tube.

2. Locking device according to claim 1, wherein the second locking means comprise a latch (38) sliding between a locking position of the hooks (30) in the cavity and an unlocking position in which the hooks are released from the imprint.

3. Locking device according to claim 2, comprising a spring (40) urging the lock into the locking position of the hooks.

4. Locking device according to any one of claims 1 to 3, wherein the intermediate tube (25) is placed inside the cylindrical tube and comprises a first end provided with a thread cooperating with a threaded rod driven by an actuator motor and a second opposite end fitting into the cylindrical tube.

5. Locking device according to claim 4, wherein said set of hooks (30) is fixed on the second end of the intermediate tube (25) and the cylindrical tube comprises internally an axial head (36) comprising a peripheral cavity in which said set of hooks engages.

6. Locking device according to claim 4, wherein said set of hooks (30) is fixed to the first end of the cylindrical tube, the intermediate tube comprising a peripheral indentation (37) into which said set of hooks engages.

7. Locking device according to any one of claims 1 to 6, wherein the hooks (30) comprise at least one inclined face capable of cooperating with a complementary ramp of the footprint.

8. Locking device according to any one of claims 1 to 7, wherein the first locking means comprise a set of at least one hook (1 1) and an indentation (16) in which engages said set of hooks ( 1 1) so as to lock the cylindrical tube (3) in the end position, said set of hooks (1 1) and the cavity (16) being carried one by the outer cylinder and the other by the cylindrical tube (3) movable, and a latch (21) sliding relative to said hooks and to the recess between a position for holding said hooks in the locking position and a position for releasing the hooks.

9. Locking device according to claim 8, wherein the latch (21) is connected in movement to the intermediate tube.

10. Electromechanical actuator, comprising a cylindrical tube (3) movable relative to a fixed outer cylinder, in which the movable tube is placed, characterized in that it comprises a locking device (1) according to any one of claims 1 to 9.