Mechanical control actuator for an aircraft

Abstract

The invention relates to a flight control actuator (11) for providing assistance to aircraft piloting means (10). This flight actuator (11) comprises an electric motor (110), an input shaft (111) adapted to be rotated by the electric motor (110), said input shaft (111) comprising an input clutch device (112), said input clutch device (112) having an active position in which it is capable of coupling the input shaft (111) with an output shaft (113) via an intermediate shaft (118), and an inactive position. The output shaft (113) is capable of being connected to the aircraft piloting means (10), said output shaft (113) being adapted to be coupled with the input shaft (111) when the input clutch device (112) is in the active position.The actuator (11) includes an emergency assist shaft (114), said emergency assist shaft (114) being adapted to be coupled with the output shaft (113) when the input clutch device (112) is in the inactive position. Figure for the abbreviation: Fig. 3.

Description

Title of the invention: Mechanical control actuator for an aircraft technical field

[0001] The present invention relates to a mechanical flight control actuator intended to provide assistance to the piloting means of an aircraft. The technical field is therefore that of mechanical flight controls in aeronautics and of actuators providing force feedback on the control stick or pedal, in particular, for a helicopter. Previous technique

[0002] In an AFCS (Automatic Flight Control System), a helicopter is piloted using equipment that controls and executes the movement of the linkage (Flight Path or Linkage), which is connected to the control surfaces or flight surfaces, according to the helicopter's dimensions, via power amplification, for example, by hydraulic valves. Piloting can be fully automatic using guidance algorithms on the one hand and stabilization algorithms for flight characteristics on the other, or semi-automatic with combined manual action on the control stick / pedals, or disengaged and in manual piloting mode.

[0003] In a helicopter, the avionics control the four steering axes (Roll / Pitch / Yaw) and the collective pitch. A classic AFCS architecture includes, to actuate the linkage travel, low-authority, high-velocity linear series actuators dedicated to flight stabilization and high-authority, low-velocity parallel rotary actuators for compensation (called "Trim" in English) which, in addition, provide force feedback in manual piloting.

[0004] In a reduced architecture, higher speed and bandwidth compensation actuators make it possible to consider stability functions as a backup or during degraded flight control performance.

[0005] In the older generation of electromechanical compensation, in manual piloting, with the force law activated, the actuators required passive friction which was achieved by mechanical devices in the linkage of the helicopter (skid on linkage, for example on collective axis).

[0006] The helicopter's friction includes a component inherent to the linkage (quite limited depending on the helicopter, ranging from 0.5 to 3 Nm, or even 5 Nm on certain axes and types of helicopters), and the compensation adjustment consists of a preload on the order of the linkage friction for pilot comfort in manual flight and slightly beyond, with a margin to guard against unintentional disengagement of the Autopilot. Depending on the type of helicopter and the axes, a localized friction device may also be required, typically up to approximately 6 Nm.

[0007] In this configuration, a passive backup friction in the linkage becomes a limitation due to its variability (underload factor, wear), and becomes a disadvantage for controlling a predetermined thrust law during nominal operation. Furthermore, for a motorized thrust law, maximum reversibility is sought to provide a free-shaft feel and to accurately and faithfully reproduce (non-linearities) a thrust law that can be adapted in flight throughout the entire flight envelope.

[0008] The pads in the linkage remain wear-prone devices, constantly under stress and therefore difficult to manage in relation to the AFCS avionics suite. This leads to periodic checks and recalibrations.

[0009] Such actuators are disclosed in particular in document US5184054 and in document US6325331.

[0010] US20180197385, for its part, mentions the use of a compensating actuator allowing passive friction inserted in a module at the output shaft or located in the linkage. This solution, however, leads to a significant volume: typically, a brake / clutch assuming forces of 20 Nm requires a volume of 80 mm diameter x 45 mm length, i.e., 16% of the targeted compact actuator volume, and with a mass of 700 g, i.e., 35% of the overall targeted mass of 2 kg of the actuator.

[0011] In addition, the mechanical friction power at the actuator output would be significant for the friction dimensioning and for the disengagement of this function which must pass the forces / kinematics of the actuator.

[0012] There is therefore a need to propose a mechanical control actuator for an actuator allowing an optimized backup function (friction, viscous damping) while having a high compactness. Description of the invention

[0013] The present invention aims to remedy at least partially this need.

[0014] More particularly, the present invention aims to provide an actuator high integrity mechanical control capable of delivering force feedback to the pilot through integrated control of its motorization.

[0015] To this end, a first object of the invention relates to a flight actuator intended to provide assistance to the piloting means of an aircraft. Said flight actuator comprising: - an electric motor; - an input shaft adapted to be rotated by the electric motor, said input shaft comprising an input clutch device, said device input clutch having an active position in which it is able to couple the input shaft with an output shaft and an inactive position; - the output shaft is suitable for connection to the aircraft's piloting means, said output shaft being adapted to be coupled with the input shaft when the input clutch device is in the active position. The actuator includes: - an emergency assist shaft, said assist shaft being adapted to be coupled with the output shaft when the input clutch device is in the inactive position, said emergency assist shaft being capable of braking and / or damping rotational movements of the output shaft, said emergency assist shaft not being capable of rotating the output shaft.

[0016] The invention consists of a novel adjustable friction and viscous damping backup function of type M = C / / (passive devices), with the particularity of a selectively applied device via an input clutch and a backup assist shaft adapted to act on the output shaft when the input clutch device is in an inactive position. Such an actuator allows for a highly compact design because this device is located in an upstream part of the equipment's transmission with a limited maximum torque on the shaft to which the unit can be activated. In nominal operation, active force feedback is ensured by torque control of the motor and estimation of the resisting torque on the output shaft, which allows for the restoration of dynamic tactile feedback with torque and damping. The intermediate shaft is suitable for carrying or performing a gear train to couple the input shaft with the output shaft.In a fully mechanical configuration, the backup power assist shaft is capable of braking and damping rotational movements of the output shaft. In a reduced configuration, the backup power assist shaft is capable of braking or damping rotational movements of the output shaft. When the backup power assist shaft is not capable of driving the output shaft's rotation, the backup assistance is passive and cannot drive the output shaft's rotation. In this case, the drive is lost. The output shaft's rotation is then induced only by the pilot and aerodynamic reactions (rotations external to the actuator). The assistance function is provided by the main function, for example, under normal operating conditions, when no error is detected by a monitoring unit. This allows the input clutch 112 to remain engaged.

[0017] In a particular embodiment, the emergency assist shaft includes an emergency assist clutch device. This emergency assist clutch device has an active position in which it drives the output shaft and an inactive position. The emergency assist clutch device is in its active position when the input clutch device is in its inactive position. inactive and said emergency assist clutch device is in its inactive position when the input clutch device is in its active position.

[0018] The adjustable friction and damping backup function is applied selectively by means of a first clutch carried by the input shaft and a second clutch carried by the backup assistance shaft. The operations of these clutches are coordinated.

[0019] In a particular embodiment, a failure of the electric motor deactivates the input clutch device and activates the backup assist clutch device. This is made possible by a monitoring unit adapted to detect failures. Thus, a failure of the electric motor is detected by the monitoring unit, which controls the dual-clutch clutch device, deactivating the input clutch device and activating the backup assist clutch device.

[0020] In the event of an error detection, the mechanical actuator switches the output shaft load in a fail-safe configuration between the driven shaft and the shaft of the passive friction / damping device within a few tens of milliseconds. Switching a load (backup assist shaft) is pleasantly perceived due to the damping of the torque transient. Furthermore, the damping on the backup assist shaft has a beneficial effect on the motor input shaft, which may have a transiently established or residual speed after being passively monitored, for example, during a 28V interruption by a circuit breaker at the power point.

[0021] In a particular embodiment, the input clutch device and the emergency assist clutch device are electrically controlled. This electrical control is common for safety reasons and features automatic shaft switching devices with a complementary dual-clutch device with three shafts. This allows for very high integrity with dual electronic and physical monitoring of the emergency assist shaft's rotation. Furthermore, the clutch devices are electrically controlled by a discrete, safe FDR (Force Drive Release).

[0022] In a particular embodiment, the emergency assistance shaft includes a braking device and / or a damping device. In a fail-safe architecture, these devices are deselected during nominal operation to eliminate any parasitic stress, with active assistance provided by the engine control unit. The emergency assistance is applied selectively. The control actuator ensures very high availability of the dual-clutch device. Positioning this actuator upstream of the transmission between the engine pinion and the downstream gear train improves the mass-to-volume ratio.

[0023] In a particular embodiment, the braking device comprises a disc friction brake, said brake being calibrated by means of spring washers. These spring washers are of the Belleville spring washer type. The braking device is thus adjustable during maintenance.

[0024] In a particular embodiment, the braking device includes a system for adjusting the calibration of the brake discs.

[0025] In a particular embodiment, the adjustment system includes a return device. This return device is located on the most accessible front face of the actuator in the aircraft installation, i.e., the output shaft side.

[0026] In a particular embodiment, the damping device includes an eddy current damper.

[0027] In a particular embodiment, the flight actuator includes an intermediate shaft disposed between the input shaft, the backup assist shaft, and the output shaft. This makes it possible to achieve a compact volume / mass objective for the passive assist unit designed between the upstream reduction stage of the engine and the downstream gear train.

[0028] In a particular embodiment, the control actuator includes dual electronic and physical monitoring of the rotation of the backup assist shaft.

[0029] Another object of the invention relates to an automatic flight control system for an aircraft comprising a mechanical flight control actuator having an emergency assist shaft, said emergency assist shaft being adapted to be coupled with the output shaft when the input clutch device is in the inactive position. The assist shaft is capable of braking and / or damping rotational movements of the output shaft, said emergency assist shaft not being capable of rotating the output shaft.

[0030] The present invention will be better understood upon reading the detailed description of embodiments taken by way of non-limiting examples and illustrated by the accompanying drawings, in which:

[0031] [Fig.1] [Fig.1] illustrates an automatic flight control system for an aircraft comprising a mechanical flight control actuator according to the invention engaged with the linkage;

[0032] [Fig.2] [Fig.2] schematically illustrates the mechanical control actuator of flight of the [Fig.l];

[0033] [Fig.3] [Fig.3] illustrates in more detail a part of the actuator of mechanical flight control of the [Fig.2];

[0034] [Fig.4] Fig.4 schematically illustrates a braking device and a device damping of the mechanical flight control actuator of the [Fig.3];

[0035] [Fig.5] [Fig.5] schematically illustrates adjustment means on the emergency assistance shaft of [Fig.4], according to a first variant;

[0036] [Fig.6] [Fig.6] schematically illustrates adjustment means on the emergency assist shaft of [Fig.4], according to a second variant.

[0037] The invention is not limited to the embodiments and variants shown and other embodiments and variants will be obvious to a person skilled in the art.

[0038] Fig. 1 illustrates an automatic flight control system 1 of an aircraft.

[0039] The automatic flight control system 1 comprises: - a control handle 10; - a mechanical flight control actuator 11; - a linear actuator 12; - a hydraulic actuator 13; - a controllable flight surface 14; - an on-board computer 15 or "Flight Control Computer FCC".

[0040] The control stick 10 is used to be held by the pilot. This stick 10 allows the pilot to control all the aircraft's linkages.

[0041] The mechanical flight control actuator 11 is adapted to provide force feedback to the control stick 10. This mechanical flight control actuator 11 is a parallel rotary actuator. It thus allows for the precise reproduction, within the flight envelope, of a force law that can be adapted in flight. This force law is a function of the angular deflection of the control stick 10. It is a digitizable force law that can be adapted in flight. In this force feedback mode for the pilot, this actuator thus assists the pilot in their control operations. In a second "autotrim" mode, the mechanical flight control actuator 11 is capable of receiving movement commands from the linear actuator 12 and the onboard computer 15.

[0042] The linear actuator 12 is coupled in series linkage to the hydraulic actuator or amplifier 13, which pushes the controllable flight surface 14. The linear actuator thus creates linear movement over a stroke on the order of millimeters to several hundred millimeters. The linear actuator 12 receives position commands and sends the current position back to the onboard computer 15, which can be responsible for the PA algorithms. In one embodiment, the PA algorithms are implemented in the processor of the linear actuator 12. Thus, the linear actuator is adapted to transform a pilot command into a specific command for the hydraulic actuator 13. More specifically, the linear actuator 12 is adapted to create straight-line movement. It receives data from the onboard computer 15.

[0043] The hydraulic actuator 13 is capable of receiving information from the actuator linear 12 in order to control the controllable flight surface 14. For the context of mechanical flight controls (as opposed to electric flight controls) the hydraulic actuator 13 amplifies the force / displacement over the stroke of the linear actuator 12 in order to control or move the controllable flight surface 14. The hydraulic actuator 13 is, for example, a hydraulic cylinder.

[0044] The controllable flight surface 14 is moved to control the flight of the aircraft. Controlling this controllable flight surface 14 contributes to the stabilization of the aircraft (four axes of control on a helicopter). The controllable flight surface 14 is thus adapted to influence the movement of the aircraft. It allows interaction between the outside air and the aircraft. This controllable flight surface 14 is here controlled around an axis of rotation X.

[0045] The on-board computer 15 is adapted to control the flight of the aircraft (Autopilot function). To this end, it acts on the control of the parallel rotary actuator (mechanical flight control actuator 11) and on the linear actuator 12.

[0046] Figure 2 schematically illustrates the mechanical flight control actuator 11 of Figure 1. This mechanical flight control actuator 11 comprises: - an electric motor 110; - an input tree 111; - an input clutch device 112; - an output tree 113; - a 114 emergency assistance tree; - an emergency assistance clutch device 115; - a braking device 116; - a damping device 117; - an intermediate tree 118; - a 120 monitoring device; - a control device 121; - a device for a logical operation 122; - a 123 gear; - a 125 protection device; - a first detector 126; - a second detector 127; - a third detector 128; - a fourth detector 129; - a fifth detector 130.

[0047] The electric motor 110 is adapted to rotate the input shaft 111. This motor 110 is a brushless DC motor which offers high reliability and allows for an optimized compromise in terms of electromagnetic density. and inertia and "cogging" torque characteristics.

[0048] The input shaft 111 is adapted to be rotated by the motor 110 via the gear 123. This input shaft 111 includes the input clutch device 112, which can also be referred to as the EM1 clutch. This clutch device 112 can be in an active position in which it couples the input shaft 111 to the output shaft 113 via the intermediate shaft 118, which carries a gear train. The input clutch device 112 can also be in an inactive position in which it does not couple the input shaft 111 to the output shaft 113. The input clutch device 112 is a friction / slip clutch.

[0049] The output shaft 113 is adapted to be coupled with the input shaft 111 when the input clutch device 112 is active via the intermediate shaft which carries a gear train. When this input clutch device 112 is inactive, the output shaft 113 is braked and / or damped by the braking device 116 and / or the damping device 117 belonging to the backup assist shaft 114.

[0050] The emergency assist shaft 114 is adapted to brake and / or dampen rotational movements of the output shaft 113, depending on the mechanical configuration mounted. This emergency assist shaft 114 includes the emergency assist clutch device 115, the braking device 116, and / or the damping device 117.

[0051] The emergency assist clutch device 115 is adapted to couple the emergency assist shaft 114 with the output shaft 113. This emergency assist clutch device 115 has an active position in which it couples the emergency assist shaft 114 with the output shaft 113. The emergency assist clutch device 115 also has an inactive position in which the emergency assist shaft 114 and the output shaft 113 are not coupled. The emergency assist clutch device 115 is in its active position when the input clutch device 112 is in its inactive position, and the emergency assist clutch device 115 is in its inactive position when the input clutch device 112 is in its active position. The input clutch device 112 and the emergency assistance clutch device 115 are therefore based on complementary logic.

[0052] The assist clutch device 112 is a friction / slip type. Alternatively, this assist clutch device 112 uses dog clutch technology.

[0053] A failure of the electric motor deactivates the input clutch device 112 and activates the backup assist clutch device 115. It should also be noted that the input clutch device 112 and the backup assist clutch device 114 are electrically controlled via the use of coils. The input clutch device 112 is current-activated, which requires, by For example, applying a voltage of 28V to the coil of said device activates it. The emergency assist clutch device 115 is fail-safe. This device is therefore active when there is no power to its coil.

[0054] The braking device 116 is adapted to brake the output shaft 113 in its rotation when the emergency assist clutch device 115 is active. This braking device 116 is a passive braking device. Advantageously, the braking device 116 is an adjustable friction device.

[0055] The damping device 117 is adapted to dampen shocks during dynamic transients induced by the linkage (aerodynamic effect on controllable flight surfaces). The damping device 117 is a passive damping device. Advantageously, the damping device 117 is a viscous device, for example, a device in which the resisting torque is proportional to the angular velocity of the supported shaft.

[0056] The braking device 116 and the damping device 117 are illustrated in particular in [Fig. 4]. The braking device 116 here comprises a disc friction brake 1161 calibrated by means of spring washers 1162. These spring washers 1162 provide an adjustable contact force between 0 and 6 Nm.

[0057] The damping device 117 is of the eddy current type and comprises a metallic disk 1171 rotating in or in front of a magnetic circuit 1172. The magnetization of the magnetic circuit 1172 can be adjusted by duplicating magnets, increasing the intercepted area of ​​the rotating disk 1171, or by treating the disk 1171, thus enabling an increase factor of approximately 30. Alternatively, the magnets can be replaced by a powered winding with a damping increase capacity of a factor of 60. The damping device 117 provides damping in the range of 1.5 to 4.5 Nm / rad / s at the output shaft 113.

[0058] The mechanical flight control actuator (parallel rotary actuator) 11 also includes the intermediate shaft 118. This intermediate shaft 118 is disposed between the input shaft 111, the backup assist shaft 114 and the output shaft 113. This intermediate shaft 118 is adapted to mechanically connect the input shaft 111 with the output shaft 113 or to mechanically connect the backup assist shaft 114 with the output shaft 113. This intermediate shaft is adapted to carry a gear train which enables a reduction ratio to be achieved.

[0059] The mechanical flight control actuator 11 includes the monitoring device 120. The monitoring device 120 monitors the transmission control chain and controls two complementary clutch devices by forcing the disengagement of the input clutch device and the backup clutch. In the event of an error detected on the drive and transmission chain, the 120 monitoring device, in the event of an error, switches the output shaft load to a fail-safe configuration between the driven shaft and the shaft of the passive friction / damping device within a few tens of milliseconds. This 120 monitoring device is suitable for transmitting a control signal to auxiliary clutch devices. The 120 monitoring device includes "HW elec" and "SW".

[0060] The control device 121 is adapted to control voltages / currents in the coils belonging to the input clutch device 112 and the backup assist clutch device 115. More particularly, this control device 121 provides supervision of the actuator modes and high-level control of the actuator as well as high-frequency motor control (servo loops).

[0061] The logic operation device 122 performs an OR logic operation. This device 122 is thus adapted to receive an FDR (For "Force Drive release") signal, and signals from the monitoring device 120 and potentially from the control device 121. This device 122 is adapted to deliver signals to the input clutch device 112 and the emergency assist clutch device 115.

[0062] The protection device 125 includes a torque limiter or fuse on the output shaft 113. This device 125 protects the mechanical chain up to the output of the output shaft 113 in the event of even a very unlikely failure related to the electromechanical components and bearing of the transmission leading to a blockage of said output shaft 113.

[0063] A monitoring device comprises a first detector 126, a second detector 127, a third detector 128, a fourth detector 129, and a fifth detector 130. These detectors allow, in particular, monitoring of the rotation of the output shaft 113. These detectors are, for example, Hall effect sensors facing a magnet mounted on a nearby disk. The principle is based on an assembly of a reducer or any other bellows-type coupling means along the axis of the output shaft 113, to couple a position / speed sensor. It should be noted that the third detector 128 is typically an independent speed sensor.

[0064] It should also be noted that the system is designed for maximum safety, allowing for high integrity in the Catastrophic class (regulatory according to CS-29, CS-25 at a probability of 10⁻⁹ / FH) or, better, for a case of error detection in the force law, with a force lower than expected or excessive, and in the absence of passivation. Indeed, the common control circuit via the Monitoring unit (an independent and segregated unit) controls the coils of both clutches. The process is also monitored. by acquiring current / voltage signals from each of the coils. In particular, beyond this monitoring, the invention enables the detection of a potential clutch fault in the passive unit, which would lead to an overload on the drive chain due to this incorrectly engaged friction. Detection is achieved through robust speed measurement by the monitoring unit via a Hall effect sensor opposite a magnet on a disc. Beyond current / voltage monitoring of the control stage of the two clutches, the invention incorporates specific rotation monitoring to ensure that the friction / damping unit is not abnormally engaged with rotation of its axis in relation to the rotation of the upstream engine-side shaft. The monitoring device 120 monitors the switching logic of the dual clutch and detects, via two different measurement circuits, the consistency of the state of the two clutches.

[0065] Finally, it should be noted that the electronics are adapted here to allow for a self-test of the drive track, using the friction backup track to load the main track's drive. In predictive maintenance, this makes it possible to calibrate the upstream transmission / drive to the predefined load and to identify an equivalent model of the loaded motor and any potential aging.

[0066] Fig. 3 illustrates in more detail a part of the mechanical flight control actuator 11 (parallel rotary actuator) comprising an electromechanical part with motor, clutches, shafts, bearings, gear trains, a friction device and a damping device.

[0067] The control state logic of the input clutch device 112 and the emergency assist clutch device 115 is as follows: - In an initialization state, the input clutch device 112 is inactive and the backup assist clutch device 115 is active. No current is injected into the clutch device coils. - In a nominal state, the input clutch device 112 is active and the backup assist clutch device 115 is inactive. A nominal current is injected into each coil. - In the event of an erroneous state following fault detection by monitoring device 120, this monitoring device 120 commands the input clutch device 112 to be inactive and the backup assist clutch device 115 to be active. No current / voltage is applied to the coils of clutch devices 112 and 115.

[0068] For ergonomic reasons and to facilitate the transition to an emergency in-flight function, the switchover between the input clutch device 112 and the emergency assist clutch device 115 is performed quickly and with compatible responsiveness of both devices. Preferably, the disengagement time of the clutch device The input 112 is faster (by approximately 5 ms) than the engagement time of the emergency clutch 115 (by approximately 10 ms). Damping on the passive unit shaft can be advantageous in the event of an emergency clutch 115 with a shaft / transmission from the engine that has a transiently established speed or a residual speed after passivation by the monitoring device 120.

[0069] In addition, the damping on the emergency assist shaft 114 is improved in the event of clutching the emergency assist clutch device 115 with the input shaft 111 which would have transiently an established speed or a residual speed after passivation by the monitoring device 120.

[0070] It will also be noted that the braking device 116 of the emergency assist shaft 114 advantageously includes a system for adjusting the calibration of the brake discs 1161 in order not to overload the emergency assist clutch device 115.

[0071] Figure 5 illustrates a first variant in which the adjustment system is a screw adjustment system. This [Fig.5] also presents a more detailed view of the braking device 116.

[0072] As already specified, the braking device 116 includes a disc 1161 and spring washers 1162. This braking device 116 further includes: - friction linings 1163; - a 1165 push button; - a screw 1166; - a lock nut 1167.

[0073] The friction linings 1163 are adapted to clamp the disc 1161 in order to brake its rotation. This disc 1161 is rotationally connected to the rest of the emergency assist shaft 114, but is free to move linearly, for example, via a keyway. In an embodiment where the emergency assist shaft 114 has sufficient axial play, the disc 1161 is rigidly fixed to this emergency assist shaft 114. The friction linings 1163 are bonded to flanges 1164.

[0074] The pusher 1165 is adapted to transmit a setting force from the screw 1166 to the spring washers 1162. The screw 1166 thus sets the spring washers 1162 and adjusts accordingly the torque and the slip of the friction assembly.

[0075] The locknut 1167 secures the screw 1166 against a cover 1168 that closes the mechanism. This cover 1168 is itself positioned on the frame 1169. This frame 1169 forms a sealed cover. It also includes an EMC seal.

[0076] Figure 6 illustrates a second variant in which the adjustment system comprises a referral mechanism.

[0077] The reference device comprises: - a return lever 1170, - a pivot 1171.

[0078] The adjustment system further comprises: - a screw 1172; - a lock nut 1173; - a spring 1174; - a push rod 1175; - disc 1161; - a push button 1176.

[0079] The push rod 1175 serves as a guide for the spring 1174 and transmits a force to the return lever 1170. The spring 1174 generates a pressure force between a lining (not shown) and the disc 1161. The push is transmitted by the rod 1175, the return lever 1170 and the pusher 1176.

[0080] The return lever 1170 is movable around the pivot 1171. This pivot is linked to the frame 1169.

[0081] The screw 1172 ensures the spring rate of the spring 1174 and consequently adjusts the slip torque of the friction assembly. The lock nut 1173 secures the screw 1172 against the frame 1169.

[0082] The invention thus provides the following advantages: - an emergency friction switch activated automatically and only in case of loss of motor control, thus optimizing reversibility and tactile feedback via motor control, natively secured in case of power loss; - a more robust selective application with long-term, reliable characteristics; - an opportunity to add amortization to the switched arrangement; - a so-called "fail-safe" switching even in the event of a loss of power to the device, with a short time; - a reduction in mass with a more compact device; - an alternative to the known and available off-the-shelf dual-clutch solution by means of an integrated and miniaturized two-state switching device with fewer parts; - an opportunity to eliminate the friction devices mounted in the linkage; - the implementation, in nominal operation, of programmable friction and damping by motor torque control, this device being easily configurable and contactless; - internal selective switching to a backup friction / damping system only in case of loss of motor control; - a negligible impact on the main function of the actuator (absence of localized friction in the linkage due to the backup function, the latter being disengaged in nominal operation; - high integrity and availability; - stable performance guaranteed over time; - high availability of the passive unit thanks to selective application; - a secure friction / damping device designed for a very high integrity "Smart Trim" action.

[0083] The invention advantageously allows, in an evolution, for the coupling of a second transmission / motorization chain to increase the availability of the actuator in a solution integrated into a single actuator housing.

Claims

Demands

1. A mechanical flight control actuator intended to provide assistance to aircraft piloting means (10), said flight actuator (11) comprising: - an electric motor (110); - an input shaft (111) adapted to be rotated by the electric motor (110), said input shaft (111) comprising an input clutch device (112), said input clutch device (112) having an active position in which it is capable of coupling the input shaft (111) with an output shaft (113) via an intermediate shaft (118) and an inactive position; - the output shaft (113) being capable of being connected to the aircraft piloting means (10), said output shaft (113) being adapted to be coupled with the input shaft (111) when the input clutch device (112) is in the active position;characterized in that said actuator (11) comprises: - an emergency assist shaft (114), said emergency assist shaft (114) being adapted to be coupled with the output shaft (113) when the input clutch device (112) is in the inactive position, said assist shaft (114) being capable of braking and / or damping rotational movements of the output shaft (113), said emergency assist shaft (114) not being capable of driving the output shaft (113) in rotation.;

2. A control actuator according to claim 1, wherein the emergency assist shaft (114) comprises an emergency assist clutch device (115), said emergency assist clutch device (115) having an active position in which it allows coupling of the emergency assist shaft (114) with the output shaft (113) and an inactive position and in that said emergency assist clutch device (115) is in the active position when the input clutch device (112) is in its inactive position and said emergency assist clutch device (114) is in its inactive position when the input clutch device (112) is in its active position.

3. Control actuator according to claim 2, wherein a failure of the electric motor (110) deactivates the input clutch device (112) and activates the clutch device emergency assistance (115).

4. Control actuator according to claim 2 or claim 3, wherein the input clutch device (112) and the backup assist clutch device (115) are electrically controlled.

5. Control actuator according to any one of claims 1 to 4, wherein the backup assist shaft (114) includes a braking device (116) and / or a damping device (117).

6. Control actuator according to claim 5, wherein the braking device (116) comprises a disc friction brake, said brake being calibrated by means of spring washers.

7. Control actuator according to claim 6, wherein the braking device (116) includes a system for adjusting the calibration of the brake discs.

8. Control actuator according to claim 7, wherein the adjustment system is a screw adjustment system.

9. Control actuator according to claim 7, wherein the adjustment system includes a return device.

10. Control actuator according to any one of claims 5 to 9, wherein the damping device (117) comprises an eddy current damper.

11. Control actuator according to any one of claims 1 to 10, wherein said flight actuator (11) comprises an intermediate shaft (118) disposed between the input shaft (111), the backup assist shaft (114) and the output shaft (113).

12. Control actuator according to any one of claims 1 to 11, said actuator comprising dual electronic and physical rotation monitoring of the backup assist shaft (114).

13. Automatic flight control system for an aircraft, the system comprising a mechanical flight control actuator (11) according to any one of claims 1 to 11.

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