GB2578204A

GB2578204A - High-lift system for an aircraft

Info

Publication number: GB2578204A
Application number: GB1912256.3A
Authority: GB
Inventors: Schievelbusch Bernd; Kohlöffel Christian; Trenkle Christian
Original assignee: Liebherr Aerospace Lindenberg GmbH
Current assignee: Liebherr Aerospace Lindenberg GmbH
Priority date: 2018-09-07
Filing date: 2019-08-27
Publication date: 2020-04-22
Anticipated expiration: 2039-08-27
Also published as: FR3085665A1; DE102018121856A1; GB2578204B; GB201912256D0; FR3085665B1

Abstract

A high-lift system for an aircraft with flaps installed on the aerofoils of the aircraft, comprises at least one central drive 11 and drive shafts 12 of which one each extend out of the central drive into one of the aerofoils. Each of the drive shafts are in communication with drive stations which are driven by the drive shafts and are in communication with the flaps for the activation thereof. Load sensors 13 are attached on the drive stations, which sensors are in communication with a central control unit. The central drive unit includes at least one hydraulic motor 15 connected with a hydraulic supply 17 via at least one continuously actuatable electrohydraulic servo-valve 19. The control unit is in communication with the control input of the servo-valve, to actively control/regulate the hydraulic motor depending the incoming sensor signals of the load sensors.

Description

Liebherr Aerospace Lindenberg GmbH Lindenberg High-Lift System for an Aircraft The invention relates to a high-lift system for an aircraft with flaps installed on the airfoils of the aircraft, as well as with at least one central drive and drive shafts, of which one each extends into one of the airfoils out of the central drive, wherein each of the drive shafts is in communication with drive stations which are driven by the drive shafts, and which are in communication with the flaps for the activation of said shafts, wherein load sensors are attached on the drive stations, which are in communication with a central control unit.

In nearly all aircrafts in the category of "transport aircraft" popular today, the high-lift systems are driven with a central drive system. The central drive unit is connected, over the entire wingspan of the aircraft, with corresponding drive stations of the individual segments of the landing flap systems or slat flap systems, by means of a rotary shaft system.

Malfunctions can occur in the activation of these flaps, on the one hand through jamming or blockage of the flap kinematics, or due to a mechanical rupture at a location of the drive train or inside the structure of one of the flap segments. If a blockage of an individual segment or a drive station occurs, the blocked segment would have to receive the further applied entire drive energy of the central drive as reaction energy. In such case, these -2 -flaps would have to be constructed solidly and heavily in order to resist such load peaks. Instead, however, it is more pragmatic to install mechanical load limiters, as a protection device, on each individual drive station, which limiters, in the defined overload case, instead make a redirecting of the drive energy in the wing structure possible in order to avoid damages at the blocked flap body/flap kinematics.

Recent developments in the field of such high-lift systems use sensor-based electronic systems instead of the mechanical load limiters, however. A sensorially detected overload situation is here counteracted through corresponding actuation of the central drive. High torque peaks, among other things, are thereby to be mitigated, which peaks, in the event of a jamming, can arise in the load paths. The inventors have, however, recognized that the advantage of such sensor-based systems can only then be fully reaped if the necessary regulating of the central drive is simultaneously optimized, in if particular the dynamics of the resulting regulating is improved.

This object is achieved by a high-lift system according to the features of the claim 1. Advantageous configurations of the system are the subject-matter of the dependent claims.

According to the invention, for the generic high-lift system, the energy supply of the at least one hydraulic motor of the central drive unit is controlled or regulated by means of a continuously actuatable electrohydraulic servo-valve for the generic high-lift system. The electric actuation of this servo-valve occurs via the control unit, which is in communication with the electric control inputs of the servo-valve provided to that end.

The control unit is, for this purpose, configured such that this unit, through corresponding actuation of the servo-valve, actively regulates the hydraulic motor depending on the incoming control signals of the load sensors.

The control of the volumetric flow to the hydraulic motor by means of the servo-valve permits, in case of error (overload), a reduction of the drive power of the central drive with a high dynamicity directly after the error detection, whereby the disadvantageous -3 -occurrence of high torque peaks can effectively be prevented. In particular, a reversal of the direction of rotation can be implemented with fast reaction.

It is preferable if different software algorithms for controlling the servo-valve are stored within the control unit. A corresponding algorithm is executed in the error-free operation (no overload). If, based on the control signal, a malfunction/overload is recognized in the control unit, the control unit switches over to an error management which correspondingly controls the hydraulic motor, in particular reduces the drive power thereof.

For example, the torque at the affected load sensor increases in the arising of a case of jamming in the rotary shaft system. If the sensorially detected torque exceeds a defined threshold value, the control unit switches over to the error management, and the hydraulic motor is reversed via targeted counter-regulating of the servo-valve, whereby the drive torque of the drive unit, as well as the torque resulting from mass inertias are significantly reduced.

According to a preferred configuration of the invention, the employed hydraulic motor of the central drive unit is characterized by a constant displacement volume. Rotational speed and/or the rotational direction of the hydraulic motor consequently permit themselves to only be set through the electrohydraulic servo-valve. Here, the upstream servo-valve makes a continuous or constant adjustment of the rotational speed and/or of the rotational direction of the hydraulic motor possible. Consequently, the control unit is suited to address the servo-valve with continuous control signals.

According to a further preferred configuration of the invention, the central drive can provide at least one further motor, which is connected or connectable, via a dedicated coupling element, with at least one drive shaft of the central drive. The at least one additional motor can e.g. be connected with the output shaft of the hydraulic motor or with an input drive-or output side of a downstream gear mechanism. E.g. such a gear mechanism includes multiple drives and/or outputs, wherein hydraulic motor and the at least one further motor are coupled to different drives of the gear mechanism. The at least -4 -one further motor is ideally an electric motor, theoretically, however, alternative drive types can find use, e.g. a further hydraulic motor.

The coupling element is preferably activatable via control inputs, in particular via the control unit. According to a preferred embodiment, an actuation of the coupling element, via the control unit, is possible in such a way, so as to activate the coupling depending on the sensor signals of the load sensors. Through the coupling element, the second motor can be connected in an error case of the first motor. The second motor constitutes, so to speak, a backup motor.

Along with the high-lift system according to the invention, the present invention likewise concerns an aircraft with such a manner of high-lift system. Consequently, the aircraft is characterized by the same advantages and features as were already demonstrated based on the high-lift system. A repetitious description can be forgone for this reason.

Further advantages and features of the inventions are meant to be explained in greater detail in the following based on exemplary embodiments represented in the figures. Shown are in: Figure 1: a functional schematic of the high-lift system according to the invention, Figure 2: a hydraulic circuit diagram of an implemented electrohydraulic servo-valve for the regulating of the hydraulic motor and Figure 3: a simplified representation of the primary components of the central drive unit of the high-lift system according to the invention.

Figure 1 exemplarily discloses the functions of the high-lift system according to the invention. The central drive unit (PDU) 10 consists of a gear mechanism 11 with the shafts and associated seals 11a, 11b, as well as the gear mechanism housing 11c. Via separate outputs of the gear mechanism 11, the respective drive shafts 12a, 12b of the different -5 -airfoils are attached. Each of the drive shafts 12a, 12b extends along one of the airfoils. Via individual drive stations, not shown here, the torque for the activation of individual flap segments, e.g. for the flaps of the landing flap system and/or the slat flap system can then be tapped.

Electronic torque sensors 13a, 13b are integrated into the drive shafts 12a, 12b. These can preferably be embodied as magneto-restrictive sensors. The sensor signals are transferred to the central control unit 18 via electrical signal connections. A position sensor 13c is integrated into the gear mechanism 11 or attached to this, in order to o measure the current shaft position. This sensor 13c delivers its measurement results to the control unit 18 as well.

The drive performance of the central drive 10 is generated via a hydraulic motor 15 with constant displacement volume as well supplementarily through an electric motor 16. Both motors 15, 16 are connected to the gear mechanism 11 via separated drives. The latter is, in addition, coupled with the gear mechanism drive via a coupling element, so that this motor can, as needed, be coupled to the drive train or be separated from this train.

The volumetric flow out of the hydraulic supply 17 to the hydraulic motor 15 is set by means of the electrohydraulic servo-valve 18, whereby the rotational direction and rotational speed of the hydraulic motor 15 can continuously be set. An example for such a servo-valve is represented in Figure 2. The servo-valve 19 includes electrical control inputs 19a, 19b, in order to constantly be able to set the flow direction as well as the flow rate. The control inputs 19a, 19b are in communication with the control unit 18 via electric signal lines.

The control unit 18 continually evaluates the continuously received sensor signals of the torque sensors 13a, 13b. If a measured load value/torque value of a sensor 13a, 13b exceeds a pre-defined threshold value, the servo-valve 19 is thus correspondingly actuated via the control inputs 19a, 19b, in order to limit or, if necessary, to reverse the volumetric flow to the hydraulic motor 15, whereby the generated drive torque of the -6 -hydraulic motor 15 can be reduced with fast reaction or can be adapted to the load case. Aside from the actuation of the servo-valve 16, the control unit 18 can, in addition, activate the coupling of the electric motor 16 in order decouple this, when necessary, from the input shaft of the gear mechanism 11.

In the arising of a case of jamming in the rotary shaft system, the torque at the affected torque sensor 13a, 13b increases until the torque exceeds a defined threshold value. An algorithm is thereby started in the electronic control unit 18, which algorithm switches over the hydraulic motor 15 through counter-regulating of the electrohydraulic servo-valve 19, and therewith significantly reduces the drive torque of the drive unit 10, as well as the torque resulting from mass inertia. Simultaneously, the electric motor 16 is separated, via the coupling, from the drive train, so that this motor can neither feed a drive torque nor a mass inertia torque.

The interplay of the respective components is again clarified through Figure 3. The individual components for a high-lift system, employed in a manner according to the invention bring about a central drive unit 10 which is characterized by a control path with comparatively high dynamicity. The advantage of the topology according to the invention lies with that, in the case of jamming, a reactively fast, significant reduction of the error loads can now be achieved. Low threshold values thereby permit themselves to be set for the error detection (torque threshold values). The reduced error loads in principle make a certain material savings possible, as the construction merely for maximum loads lower in terms of amount can be developed. In total, a reduced complexity of the mechanical and hydraulic components results, and thereby a better availability of the overall system.

The combination of load measurement, hydraulic motor with constant displacement volume and electrohydraulic servo-valve leads to a very high dynamicity of the control path, and thus serves to reduce the loads through error count in case of jamming. Swift counter-regulating of the motor (in the opposite direction) serves to mitigate the mass inertial effects (in particular of the motor) in the system. -7 -

Claims

Liebherr-Aerospace Lindenberg GmbH Lindenberg High-Lift System for Aircraft Claims 1. High-lift system for an aircraft with flaps installed on the airfoils of the aircraft, as well as with at least one central drive and drive shafts, of which one each extends out from the central drive into one of the airfoils, wherein each of the drive shafts is in communication with drive stations which are driven by the drive shafts, and which are in communication with the flaps for the activation thereof, wherein load sensors are attached on the drive stations, which sensors are in communication with a central control unit, characterized in that the central drive unit includes at least one hydraulic motor, the hydraulic connection of which is, via at least one continuously actuatable electrohydraulic servo-valve, in communication with the hydraulic supply, and wherein the control unit is in communication with the control input of the servo-valve in order to actively control/regulate the hydraulic motor depending upon the incoming control signals of the load sensors. -8 -
High-lift system according to claim 1, characterized in that, through the electrohydraulic servo-valve, the rotational speed and/or the rotational direction of the hydraulic motor can continuously be set.
High-lift system according to claim 1 or 2, characterized in that the control unit is configured to compare the incoming measurement values of the load sensors against threshold values and, in an exceeding of a threshold value, actuates the servo-valve in such a manner that the drive torque of the hydraulic motor is reduced or, if necessary, reversed.
4. High-lift system according to one of the preceding claims, characterized in that the hydraulic motor provides a constant displacement volume.
5. High-lift system according to one of the preceding claims, characterized in that the central drive provides at least one further motor which, as required, is connectable with at least one drive shaft via a coupling, the hydraulic motor and/or the at least one further motor are in particular connected with the drive shafts of the airfoils via a gear mechanism.
6. High-lift system according to claim 4, characterized in that the at least one further motor is an electric or hydraulic motor.
High-lift system according to one of the preceding claims, characterized in that the load sensors are electrical torque sensors, preferably magneto-restrictive sensors.
High-lift system according to one of the preceding claims, characterized in that the control unit is suited to address the servo-valve with continuous control signals.
9. Aircraft with at least one high-lift system according to one of the preceding claims.