WO2022123170A1

WO2022123170A1 - Device for locking an electromechanical actuator provided with improved means for protecting against seizing or blocking

Info

Publication number: WO2022123170A1
Application number: PCT/FR2021/052229
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: FR3117089A1; FR3117089B1

Abstract

This locking device for an electromechanical actuator comprising a cylindrical tube (3) which is movable with respect to a fixed outer casing (2), under the action of actuating drive means (4), and first releasable locking means (8) for locking the cylindrical tube in the fixed outer casing. It comprises second complementary releasable locking means (9) for locking the cylindrical tube (3) that operate independently of the first locking means and are interposed between the drive means and the cylindrical tube, the second releasable locking means (9) comprising an intermediate tube (25) able to be moved translationally by the drive means and to cause the translational movement of the cylindrical tube (3), a bearing in which the intermediate tube swivels, and an assembly of at least one hook (30) engaging in an indentation (37), the assembly of hooks and the indentation being placed, for one of them, on the bearing and, for the other, on the casing (2).

Description

DESCRIPTION

TITLE: Device for locking an electromechanical actuator equipped with means of protection against seizures or advanced blockages

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 gears are 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 actuation and locking system of the hydraulic trains has certain drawbacks, such as require 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.

Requirements in terms of reliability and safety require, in addition, to obtain 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 1 49 496 and to document FR 1 756 035 which describes a locking device and an electromechanical actuator for aircraft landing gear, the extended position e of which constitutes an automatic locking position.

This di spositi f uses a set of hooks which fit into a cavity when the train is in the extended position, a retractable lock locking the hooks in the cavity.

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 with respect to a fixed outer casing, under the action of actuating motor means, and first releasable means for locking the tube cylindrical in the fixed outer casing.

This device comprises second releasable means for complementary locking of the cylindrical tube operating independently of the first locking means and interposed between the motor means and the cylindrical tube, the second releasable locking means comprising an intermediate tube able to be moved in translation by the motor means and to cause the movement in translation of the cylindrical tube, a bearing in which is journalled the intermediate tube and a set of at least one hook engaging in a recess, said set of hooks and the recess being placed one on the bearing and the other on the casing. Thus, when the hooks are placed in the cavity, the second locking means ensure the connection between the drive means and the cylindrical tube, during normal operation. In the event of a malfunction, their unlocking allows release of the actuator by releasing the bearing. The second locking means thus constitute an emergency device providing protection against seizures, blockages or other malfunctions, the hooks securing the intermediate tube and the casing in normal operation and disengaging them on demand if necessary, in the event of seizure or failure of the actuator, regardless of its position. When the locking device is used in a landing gear actuator, then the gear can 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 latch into the locking position of the hooks, said spring being interposed between the bearing and the latch. In one embodiment, the intermediate tube is mounted inside the cylindrical tube so as to be driven in rotation by an actuating motor and an external thread cooperating with the cylindrical tube by means of a hollow ball screw.

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

Advantageously, the hooks have a bevelled shape and comprise two inclined faces.

In one embodiment, the hooks are fixed to the casing and the recess is made in the bearing.

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

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

The invention also relates, according to another aspect, to an electromechanical actuator comprising a cylindrical tube movable relative to a fixed outer casing 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 one embodiment of the invention;

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

There is shown in Figure 1 an 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, this does 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 casing 2 and an inner cylindrical tube 3 movable in the fixed outer casing 2 between a fully extended position, which corresponds to an exit position of the train and a retracted position, which corresponds to a retracted position of the train. landing, under action of motor means 4 comprising a rotary drive shaft 5, which may be a splined shaft, for example associated with a motor 6 for actuating the actuator 1, illustrated schematically ue.

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

As can be seen, the outer casing 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 casing 2. The claws

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

11 comprising an elastic arm 12 and an end head 13 comprising an internal face, turned towards 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 casing.

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 casing 2. On the distal side, it is bordered by a ramp 18 for snapping the end head 13 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 casing 2 and extends mainly in the cylindrical tube 3.

The intermediate tube 25 is placed around the drive shaft 5 .

It is connected in rotation to the rotational drive shaft 5 but can translate freely on this shaft. It constitutes a hollow screw which has externally a thread 28 which cooperates with a hollow ball screw sleeve 29 fixed to the proximal end of the cylindrical tube so that the rotation of the drive screw 5 and the subsequent rotation of the intermediate tube 25 causes the translational movement of the cylindrical tube 3.

The locking device is also provided with a bearing 30 in which the intermediate tube 25 swirls, via a roller or bearings 31 .

In normal operation, that is to say in the absence of seizing of the motor means or in the absence of a drop in the efficiency of the actuator, the bearing 30 is linked to the casing 2.

To do this, the second locking means comprise a set of claws 32 similar to the claws 10 of the first locking means, each comprising at their free end an elastic hook 33 comprising an elastic arm 34 fixed to the casing 2 and a head end 35 comprising a bevelled radially inner face delimiting two ramp surfaces proximal e 36 and distal 37.

The peripheral surface of the bearing 30 comprises for its part an annular indentation 38 (FIG. 3), of complementary shape to the end head 35 which forms a housing for receiving the head 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 38. Second locking means 40, consisting of a sliding lock maintain the claws in the cavity.

While the first lock 21 is activated and deactivated under the action of the rotation drive shaft 5, the second unlocking means are activated by an external actuator (not shown), for example a cable actuator, or by any other suitable means, such as a motor or an electromagnet.

A spring 41 is interposed between the bearing 30 and the lock 40 to urge the latter into a position for locking the claws in the recess.

This embodiment operates as follows.

As shown in Figure 2, when the motorized screw 5 is actuated, the intermediate tube 25 is driven in rotation, causing a subsequent movement in translation of the cylindrical tube 3 to its output position.

In this position, the first locking means snap into recess 16. The deployed position of the actuator is locked by latch 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 seizure, the lock 40 is retracted. When the claws 32 are released from the lock 40, these are spontaneously released from the recess 38 under the action of the ramp or slope 36 and the complementary shape of the recess. The cylindrical tube 3 is then released, authorizing the exit of the cylindrical tube 3 under the action of gravity or manually.

At the end of the stroke of the cylindrical tube 3, the first locking means are activated.

The actuator thus comprises two holding bearings on the proximal side, namely a main bearing which is always hooked to the casing, and a secondary bearing which is kept linked to the casing by a claw. It is the release of this claw in emergency mode, which frees the whole comprising this secondary bearing, the cylindrical tube 3 and the intermediate tube 25, with its secondary bearing and the complete ball screw 29. This is made possible by the hollow ball screw and the drive shaft 5 which authorizes the transaction of all this crew.

In the embodiment which has 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 performed automatically by rotating the rotational drive shaft 5 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 release the output rod when manual or emergency operation is necessary without 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 casing (2), under the action of drive means (4) for actuation, and first releasable means (8 ) for locking the cylindrical tube in the fixed outer casing, 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) able to be driven in rotation by the motor means and to cause the translational movement of the cylindrical tube (3), a bearing in which the tube is journalled intermediate and a set of at least one hook (30) engaging in a recess (38), said set of hooks and the recess being placed one on the bearing and the other su r the housing (2).

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 footprint.

3. Locking device according to claim 2, comprising a spring (41) urging the latch into the locking position of the hooks, said spring being interposed between the bearing and the latch (38).

4. Locking device according to any one of claims 1 to 3, wherein the intermediate tube (25) is mounted inside the cylindrical tube so as to be rotated by an actuating motor and an external thread cooperating with the cylindrical tube (3) by means of a hollow ball screw.

5. Locking device according to any one of claims 1 to 4, wherein the hooks (30) comprise at least an inclined face capable of cooperating with a complementary ramp of the cavity.

6. Locking device according to claim 5, wherein the hooks have a bevelled shape and comprise two inc lined faces.

7. Locking device according to any one of claims 1 to 6, wherein the hooks are fixed to the housing and the recess is formed in the bearing.

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 (11) and an indentation (16) in which said set of hooks engages ( 11) so as to lock the cylindrical tube (3) in the end position, said set of hooks (11) and the recess (16) being carried one by the outer casing 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 linked in movement to the intermediate tube.

10. Electromechanical actuator, comprising a cylindrical tube (3) movable relative to a fixed outer casing, 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.