Measuring device, Electromechanical actuator tip, electromechanical actuator and associated manufacturing method

Abstract

Measuring device, electromechanical actuator tip, electromechanical actuator and associated manufacturing method The present invention relates to a measuring device (15) for an electromechanical actuator (1), in particular for an aircraft, the electromechanical actuator (1) comprising: - an electric motor (3) arranged in a metal structure (5), - a movable member (9) configured to be moved by the electric motor (3), the measuring device (15) is configured to be arranged in the metal structure (5) of the electromechanical actuator (1) and comprises: - a position sensor (25) of the movable member (9), - a force sensor (27) configured to measure the force applied by the electromechanical actuator (1) and, - a processing unit (35) for signals from the position sensor (25) and / or the force sensor (27). Fig.1

Description

Title of the invention: Measuring device, Electromechanical actuator tip, electromechanical actuator and associated manufacturing method

[0001] The present invention relates to a measuring device for an electromechanical actuator and in particular for electromechanical actuators for aircraft. The present invention also relates to an actuator tip and an actuator comprising such a measuring device as well as an associated manufacturing method.

[0002] Aircraft use many actuators. These actuators are used to control the positioning of elements, in particular directional elements such as ailerons or deflectors. Sensors such as position or force sensors are associated with these actuators to enable the desired positioning of the element to be obtained. Some elements may be connected to several actuators acting in parallel, either because of the size of the element or to obtain redundancy of the actuators and thus improve safety. It is then appropriate to control the various actuators in a suitable manner to avoid deformation such as twisting of the elements to be actuated.

[0003] In order to obtain the aforementioned characteristics while ensuring maximum reliability of these actuators, the importance of which is crucial because they directly influence passenger safety, hydraulic actuators have been favored until now by aeronautical manufacturers and equipment manufacturers because the hydraulic parts can be easily put into inactive and passive mode to allow redundancy in the event of a malfunction of one of the two actuators arranged in parallel.

[0004] However, in order to limit the energy consumption of aircraft, the current trend is to reduce the weight of aircraft as much as possible. However, hydraulic actuators have a significant weight so that aircraft manufacturers are looking for solutions to reduce the weight of these actuators.

[0005] One solution is to use electromechanical actuators which must also in certain cases operate in parallel like hydraulic actuators so that it is necessary to be able to accurately measure the force applied by each actuator. In addition, electromechanical actuators use mechanical connections such as screw-nut assemblies which could seize up before reaching the estimated lifetime of the aircraft (generally 25 or 30 years) due to the number of cycles to be applied and the stresses undergone (micro-displacements, vibrations, thermal cycles, humidity).

[0006] In order to make an electromechanical actuator suitable for aeronautical use, it It is therefore necessary to find a solution to maximize the actuator's lifespan and / or maximize the mean time before failure (MTBF), to be able to detect signs of actuator seizure before reaching a malfunction or failure of the actuator and to limit a mechanical overload that the electromechanical actuator could apply to the aircraft's structural element.

[0007] The present invention therefore aims to provide a solution making it possible to obtain a reliable actuator with reduced weight.

[0008] To this end, the present invention relates to a measuring device for an electromechanical actuator, in particular for an aircraft, said electromechanical actuator comprising: - an electric motor placed in a metal structure, - a moving member configured to be moved by the electric motor, the measuring device is configured to be arranged in the metal structure of the electromechanical actuator and comprises: - a position sensor for the moving part, - a force sensor configured to measure the force applied by the electromechanical actuator and, - a unit for processing signals from the position sensor and / or the force sensor.

[0009] The use of a unit for processing signals from the position and / or force sensors integrated into the structure of the electromechanical actuator makes it possible to increase the accuracy of the measurements, to simplify the transmission of the measurements to the outside of the actuator and to limit the number and length of cables necessary for the operation of the electromechanical actuator.

[0010] According to another aspect of the present invention, the measuring device also comprises a temperature sensor and the processing unit is also configured to process signals from the temperature sensor.

[0011] According to another aspect of the present invention, the displacement sensor is a variable differential transformer comprising a plurality of coils forming a primary winding and two secondary windings in the center of which is arranged a ferromagnetic core configured to move with the movable member.

[0012] According to another aspect of the present invention, the force sensor comprises a plurality of strain gauges disposed on at least one test body configured to deform as a function of the force applied by the electromechanical actuator.

[0013] According to another aspect of the present invention, the at least one test body is provided directly in the metal structure of the electromechanical actuator.

[0014] According to another aspect of the present invention, the processing unit is configured to apply thermal compensation to the measurements of the position and / or force sensors in order to improve the measurement accuracies.

[0015] According to another aspect of the present invention, the processing unit is disposed in a hermetic or sealed housing of the metal structure to improve reliability.

[0016] According to another aspect of the present invention, the measuring device comprises a hermetic connection or a hermetic connector configured to provide an electrical connection between the processing unit and the exterior of the metal structure, said hermetic connection or said hermetic connector comprising a seal with glass beads.

[0017] According to another aspect of the present invention, the processing unit is configured to digitally calibrate the position and / or force and / or temperature sensors by power line via the power supply wires of the processing unit in order to limit the number of cables between the processing unit and the exterior of the metal structure.

[0018] According to another aspect of the present invention, the processing unit is configured to apply a self-test of the position sensor and / or the force sensor to verify their correct operation in response to the reception of an external command.

[0019] The present invention also relates to an electromechanical actuator tip comprising a first part of the metal structure of the electromechanical actuator in which a measuring device as described above is arranged.

[0020] According to another aspect of the present invention, the first part comprises a hermetic or sealed housing.

[0021] According to another aspect of the present invention, the end piece comprises a metal cover configured to close the housing hermetically or watertight, said metal cover being welded to the first part of the metal structure.

[0022] The present invention also relates to an electromechanical actuator comprising: - an electric motor placed in a metal structure, - a movable member configured to be moved by the electric motor, - an electromechanical actuator tip as described previously, - a second part of the metal structure.

[0023] The present invention also relates to a method of manufacturing an electromechanical actuator tip as described previously comprising a step of machining the metal structure to form one or more zones forming a test body configured to receive the strain gauges.

[0024] Method of manufacturing an electromechanical actuator tip as described above previously comprising a step of welding the metal cover onto the metal structure, in particular by electron beam or laser welding.

[0025] Other advantages and characteristics will appear on reading the description of several illustrative but non-limiting examples of the present invention, as well as the appended drawings in which:

[0026] [Fig-1] [Fig.l] is a sectional view of an electromechanical actuator according to the present invention;

[0027] [Fig.2] [Fig.2] is a first perspective and sectional view of an instrumented tip of an electromechanical actuator according to the present invention;

[0028] [Fig.3] [Fig.3] is a second perspective and sectional view of an instrumented tip of an electromechanical actuator according to the present invention;

[0029] [Fig.4] [Fig.4] is a perspective view of an instrumented tip of an electromechanical actuator according to the present invention;

[0030] [Fig.5] [Fig.5] is a schematic representation of a processing unit of an instrumented tip of an electromechanical actuator according to the present invention;

[0031] [Fig.6] [Fig.6] is a flowchart of the steps of a method of manufacturing an electromechanical actuator tip according to the present invention.

[0032] In these figures, identical elements have the same reference numbers.

[0033] The following embodiments are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the features apply only to a single embodiment. Single features of different embodiments may also be combined or interchanged to provide other embodiments.

[0034] The present invention relates to an electromechanical actuator, in particular for an aircraft, and in particular to a measuring device intended to be arranged in such an electromechanical actuator.

[0035] [Fig.l] represents a sectional view of such an electromechanical actuator 1.

[0036] The electromechanical actuator 1 comprises an electric motor 3 comprising a stator 3a and a rotor 3b. The electric motor 3 is arranged in a metal structure 5 forming a protective casing for the electric motor 3. The metal structure 5 has for example an elongated shape, in particular a cylindrical shape and can be formed of a first part 5a and a second part 5b. The metal structure 5 is for example made of steel or aluminum. The metal structure 5 also comprises a first fixing element 7 arranged for example on the first part 5a of the metal structure 5. The first fixing element 7 comprises for example a pivot connection made by an annular bearing or a ball joint connection made by a spherical bearing 70.

[0037] The electromechanical actuator 1 also comprises a movable member 9 in translation along a longitudinal axis of the electromechanical actuator 1. The movable member 9 projects from a second part 5b of the metal structure 5, on the side opposite the first part 5a.

[0038] The movable member 9 is configured to be moved by the electric motor 3, for example via a ball screw 11 arranged between the rotor 3b of the electric motor 3 and the movable member 9. The ball screw 11 makes it possible to transform the rotational movement of the rotor 3b of the electric motor 3 into a translational movement of the movable member 9 while limiting friction. However, other devices can be used to allow the movement of the movable member 9 from the rotation of the rotor 3b of the electric motor 3, in particular a simple screw-nut assembly.

[0039] The movable member 9 also comprises a second fixing element 13 which may be similar to the first fixing element 7 but may also be different. The first fixing element 7 may for example comprise a pivot connection and the second fixing element 13 comprise a ball joint or vice versa. In the example of [Fig.l] the first fixing element 7 and the second fixing element 13 are identical and each comprise a spherical bearing 70.

[0040] The electromechanical actuator 1 also comprises bearings 12 for guiding the mobile element 9 and bearings 14 for guiding the rotor 3b of the electric motor 3.

[0041] The electromechanical actuator may also comprise stops 16 for stopping the movable element 9.

[0042] The electromechanical actuator 1 also comprises a device 15 for measuring the movements of the movable member 9. This measuring device 15 is for example arranged in an internal housing 17 (visible in FIGS. 2 and 3) of the metal structure 5. The internal housing 17 is for example arranged in the first part 5a of the metal structure 5. The first part 5a of the metal structure and the measuring device 15 form an end piece of the electromechanical actuator 1. The present invention also relates to such an end piece of the electromechanical actuator 1.

[0043] The internal housing 17 is for example closed by a metal cover 19. The metal cover 19 is for example welded, in particular by electron beam or by laser welding, to the metal structure 5 to form an internal housing 17 which is hermetic, that is to say which prevents any passage of air or watertight, that is to say which prevents any passage of water. The passage of the cables 21 connecting the measuring device 15 and the exterior of the metal structure 5 is for example achieved via a connector 23 or a hermetic or watertight connection.

[0044] Obtaining a hermetic connection or connector 23 is for example obtained via sealing with glass beads. Obtaining a connection or connector waterproof is for example obtained by applying around the connector or the cable (in the case of a waterproof connection) a coating formed in particular by an adhesive.

[0045] The measuring device 15 comprises a position sensor 25, for example a linear variable differential transformer (LVDT) as in the various figures. Other types of position sensor can also be used.

[0046] In the example presented, the LVDT type position sensor comprises a plurality of coils forming on the one hand a primary winding configured to be powered by an alternating voltage and on the other hand two secondary windings in the center of which is arranged a ferromagnetic core. The ferromagnetic core is configured to move with the movable member 9 so that the movement of the movable member 9 varies the voltage induced in the secondary windings. This technology allows reliable and contactless position measurement which makes it possible to maximize the service life of the position sensor 25.

[0047] The measuring device 15 also comprises a force sensor 27 configured to measure the force applied by the electromechanical actuator 1.

[0048] The force sensor 27 is for example produced by strain gauges 270 arranged on one or more test bodies 29 arranged in or near the force path, i.e. configured to deform as a function of the force applied by the electromechanical actuator 1.

[0049] The test body or bodies 29 are for example directly formed or machined in the metal structure 5 and in particular in the housing 17 of the first part 5a of the metal structure 5. As shown in [Fig. 4], the metal structure 5 is for example machined to form a central element 31 connected to a peripheral zone 33 via a plurality of arms or beams 29 extending radially and forming the different test bodies. Alternatively, the test body or bodies may be formed by cavities formed directly in the metal structure 5.

[0050] The measuring device 15 also comprises a processing unit 35 configured to process the signals from the position sensor 25 and / or the force sensor 27. The processing unit 15 is also configured to be arranged in the housing 17.

[0051] In the case where the processing unit 35 only processes the signals from the position sensor 25, the signals from the force sensor 27 are transmitted directly to the outside of the electromechanical actuator 1, for example via the hermetic connector 23.

[0052] In the case where the processing unit 35 only processes the signals from the force sensor 27, the signals from the position sensor 25 are transmitted directly to the outside of the electromechanical actuator 1, for example via the connector hermetic 23.

[0053] The measuring device 15 may also comprise a temperature sensor 39. The temperature sensor is for example a thermocouple or a thermistor.

[0054] [Fig. 5] represents an exemplary embodiment of a processing unit 35.

[0055] In the case of [Fig.5], the temperature sensor 39 is arranged in the processing unit 35 but the temperature sensor 39 can also be external with respect to the processing unit 35. The processing unit 35 is configured to apply a temperature compensation of the measurements of the position sensor 25 and / or the force sensor 27.

[0056] The processing unit 35 comprises means 41 for shaping a power supply signal for the position sensor 25, for example to power the primary winding of the position sensor 25, for example by a sinusoidal voltage and / or means 43 for shaping a power supply signal for the force sensor 27, for example to power a Wheatstone bridge in which the strain gauges 270 are arranged by a direct voltage. These power supply signals can be generated from a common power supply 45, for example a 15V DC power supply.

[0057] The common power supply 45 is obtained via an electrical cable connected to the hermetic connector 21 and configured to transmit an electrical power supply current. In addition, in order to reduce the number of cables between the processing unit 35 and the exterior of the metal structure 5, the electrical potential associated with the electrical power supply current may be a carrier current whose modulation makes it possible to digitally calibrate the output signals from the position sensors 25 and / or force sensors 27 and / or temperature sensors 39.

[0058] The processing unit 35 may also comprise means 47 for demodulating the signals from the position sensor 25, digital-to-analog converters 49 intended for calibration, filters, in particular low-pass filters 51 or filters 53 for interference and electromagnetic compatibility (“ElectroMagnetic Interference (EMI) and Electromagnetic Compatibility (EMC) filters” in English) or other electronic components useful for supplying or processing the signals from the position sensors 25 and / or force sensors 27.

[0059] The processing unit 35 can also be configured to perform self-test functions on the various sensors 25, 27 and 39. The self-test is for example performed when a self-test command from outside the electromechanical actuator 1 is received by the processing unit 35. The self-test consists for example in putting the electromechanical actuator into a predefined state (or a succession of predefined states) and in verifying that the measurements provided by the sensors in this or these predefined state(s) are included in a predefined measurement interval. The performance of a This self-test allows verification of the correct functioning of the position and / or force and / or temperature measurement chain via an external command.

[0060] The processing unit 35 can also be configured to apply functions for monitoring the correct operation of the position sensor 25 and / or force sensor 27 and / or temperature sensor 39 via self-tests at predetermined times (for example when the electromechanical actuator 1 is powered up or at regular or predefined time intervals.

[0061] The processing unit 35 can be arranged on a single printed circuit board (PCB) to limit its size.

[0062] Thus, the measuring device 15 comprising the position sensors 25 and / or force sensors 27 and / or temperature sensors 39 and / or the processing unit 35 is arranged in the internal housing 17, which makes it possible to improve the immunity of the electromechanical actuator 1 to electromagnetic disturbances.

[0063] This integration of the processing unit 35 within the electromechanical actuator 1 near the position sensor 25 and the force sensor 27 makes it possible to eliminate the connecting cables between the sensors 25 and 27 and an external processing unit, which in particular makes it possible to reduce the size of these sensors 25 and 27 and in particular the diameter of the position sensor 25, which makes it possible to reduce the diameter of the electromechanical actuator 1. The elimination of the connecting cables between the sensors 25 and 27 and the processing unit 35 also makes it possible to reduce the losses linked to the transmission of the signals, which makes it possible to improve the accuracy of the measurements.

[0064] Thus, the integration of a measuring device 15 comprising a position sensor 25, a force sensor 27 and a processing unit 35 in an electromechanical actuator 1 makes it possible not only to provide an electromechanical actuator 1 usable in an aircraft since it provides precise position and force measurements but also to protect the measuring device 15 from the environment due to the positioning of the measuring device 15 in a hermetic or sealed internal housing 17. This also makes it possible to reduce the size of the electromechanical actuator 1, in particular the external diameter of the electromechanical actuator 1.

[0065] The integrated position 25 and force 27 or even temperature 39 sensors also make it possible to effectively detect a problem or a breakdown in the electromechanical actuator 1 and in particular a seizure, for example of the screw-nut system 11, leading to an abnormal force variation for a given position variation or an abnormal temperature rise. The self-test function also makes it possible to detect a breakdown of the position sensor 25 or of the force sensor 27 or of the temperature sensor 39.

[0066] Such integration of the measuring device 15 and in particular of the processing unit 35 makes it possible to reduce the number of connecting wires between the inside and the outside of the electromechanical actuator 1, to simplify the interface with the sensors 25 and 27, to simplify the acquisition of measurements linked to the sensors 25 and 27 and to reduce the overall consumption of the electromechanical actuator 1.

[0067] The present invention is not limited to the embodiment described but can also be applied to other types of electromechanical actuators, in particular rotary electromechanical actuators. In the case of a rotary electromechanical actuator, the torque supplied by the electric motor can be used directly or via a reducer, the position sensor is for example a rotary variable differential transformer (RVDT) and the torque sensor can also be made from strain gauges arranged in the force path and configured to deform under the action of a torque supplied by the electric motor. Other types of position or force sensors can also be used.

[0068] The present invention also relates to a method of manufacturing a tip of an electromechanical actuator 1 as described previously.

[0069] [Fig.6] represents the different stages of this manufacturing process.

[0070] The first step 101 concerns a step of machining a part 5a of a metal structure 5, for example made of steel, of the electromechanical actuator 1, to form an end piece of the electromechanical actuator 1.

[0071] This first step 101 comprises a first sub-step 1011 of producing an internal housing 17 arranged in the first part 5a of the metal structure 5. The internal housing 17 is configured to receive a measuring device 15 as described previously.

[0072] The first step 101 also comprises a second sub-step 1012 of producing one or more test bodies directly in the metal structure 5. The test body is for example produced by a central element 31 connected to a peripheral zone 33 via a plurality of beams 29 extending radially to form different test bodies intended to receive the strain gauges 270 of the force sensor 27. Alternatively, one or more cavities can be provided to form the test body(ies).

[0073] The second step 102 concerns a step of machining a metal block, for example made of steel, to provide a metal cover 19 comprising a base 19a, for example in the form of a disc, and a tube 19b corresponding to the external body of the position sensor 25 extending perpendicular to the plane of the base 19a on a first side of the base 19a.

[0074] The third step 103 concerns the assembly of a sliding rod projecting from the end of the tube 19b of the metal cover 19. This sliding rod comprises the ferromagnetic core of the position sensor 25 and is configured to be connected to the moving organ 9.

[0075] The fourth step 104 concerns the mounting of the measuring device 15, i.e. the position sensors 25 and force sensors 27, or even temperature sensors 39, as well as the processing unit 35 in the internal housing 17. A part of the internal housing 17 is located in the metal cover 19.

[0076] The fifth step 105 concerns the fixing of the metal cover 19 on the metal structure 5 by welding to close the internal housing 17. The welding is for example carried out by electron beam or by laser.

[0077] The order of the steps of the manufacturing process may be different from the order shown and certain steps of the manufacturing process shown may be optional or replaced by other manufacturing steps.

Claims

Claims

1. Electromechanical actuator tip (1), in particular for aircraft, comprising a first part (5a) of a metal structure (5) of an electromechanical actuator (1) in which a measuring device (15) is arranged, the electromechanical actuator (1) comprising: - an electric motor (3) arranged in the metal structure (5), - a movable member (9) configured to be moved by the electric motor (3), characterized in that the measuring device (15) comprises: - a position sensor (25) of the movable member (9), - a force sensor (27) configured to measure the force applied by the electromechanical actuator (1) and comprising a plurality of strain gauges (270) arranged on at least one test body (29) configured to deform as a function of the force applied by the electromechanical actuator (1), the at least one,test body is arranged directly in the metal structure (5) of the electromechanical actuator (1), - a processing unit (35) for signals from the position sensor (25), and / or the force sensor (27).,

2. Electromechanical actuator tip (1) according to the preceding claim in which the measuring device (15) also comprises a temperature sensor (39) and in which the processing unit (35) is also configured to process signals from the temperature sensor (39).

3. Electromechanical actuator tip (1) according to claim 1 or 2 wherein the displacement sensor (25) is a variable differential transformer comprising a plurality of coils forming a primary winding and two secondary windings in the center of which is arranged a ferromagnetic core configured to move with the movable member (9).

4. Electromechanical actuator tip (1) according to one of the preceding claims in combination with claim 2 in which the processing unit (35) is configured to apply thermal compensation to the measurements of the position (25) and / or force (27) sensors.

5. Electromechanical actuator tip (1) according to one of the preceding claims in which the processing unit (35) is arranged in a hermetic or sealed housing (17) of the metal structure (5).

6. An electromechanical actuator tip (1) according to claim 4 or 5 comprising a hermetic connection or a hermetic connector (21) configured to provide an electrical connection between the processing unit (35) and the exterior of the metal structure (5), said hermetic connection or said hermetic connector (21) comprising a seal with glass beads.

7. Electromechanical actuator tip (1) according to one of the preceding claims in which the processing unit (35) is configured to digitally calibrate the position (25) and / or force (27) and / or temperature (39) sensors by carrier current via the power supply wires of the processing unit (35) in order to limit the number of cables between the processing unit (35) and the exterior of the metal structure (5).

8. Electromechanical actuator tip (1) according to one of the preceding claims wherein the processing unit (35) is configured to apply a self-test of the position sensor (25) and / or the force sensor (27) to verify their correct operation in response to the reception of an external command.

9. Electromechanical actuator tip (1) according to one of the preceding claims in which the first part (5a) comprises a hermetic or sealed housing (17).

10. Electromechanical actuator tip (1) according to the preceding claim comprising a metal cover (19) configured to close the hermetic or sealed housing (17), said metal cover (19) being welded to the first part (5a) of the metal structure (5).

11. Electromechanical actuator (1) comprising: - an electric motor (3) arranged in a metal structure (5), - a movable member (9) configured to be moved by the electric motor (3), - an electromechanical actuator tip according to one of the preceding claims, - a second part (5b) of the metal structure (5).

12. Method of manufacturing an electromechanical actuator tip (1) according to one of claims 1 to 10, comprising a step of machining (1012) the metal structure (5) to form one or more zones (29) forming a test body configured to receive the strain gauges (270).

13. Method of manufacturing an electromechanical actuator tip (1) according to claim 10 comprising a step (105) of welding the metal cover (19) onto the metal structure (5), in particular by electron beam or laser welding.

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