Method for controlling aircraft braking by an eddy current braking device

Abstract

Method for controlling braking of an aircraft comprising at least one control member (11) providing a value of at least one braking control parameter, and an eddy current magnetic braking device (1), comprising the steps of: acquiring the value of the braking control parameter and values ​​of state parameters of the magnetic braking device (1) and determining a braking torque command and an air gap setpoint and / or a supply current setpoint from a model recorded in the electronic processing unit (7) and which relates values ​​of the braking control parameter, values ​​of braking torque, values ​​of air gap and values ​​of supply currents as a function of the state parameters of the magnetic braking device (1). Magnetic braking device implementing this method. FIGURE OF THE ABSTRACT: Fig. 1

Description

Title of the invention: Method for controlling the braking of an aircraft by an eddy current braking device

[0001] The present invention relates to the field of braking and more particularly to the braking of aircraft wheels.

[0002] BACKGROUND OF THE INVENTION

[0003] An aircraft wheel generally comprises a rim connected by a web to a hub mounted to rotate on a wheel support shaft (axle or spindle). A braking device is fitted to the wheel to enable it to be braked at the request of the aircraft pilot, the braking device being sized according to the greatest force that he has to provide, i.e. on landing.

[0004] The most widespread braking devices are friction braking devices comprising a stack of braking discs which is housed in a space extending between the rim and the hub and which comprises an alternation of rotor discs linked in rotation with the wheel and stator discs fixed relative to the wheel support. The braking device also comprises hydraulic or electromechanical actuators mounted on an actuator holder and arranged to apply a controlled braking force to the stack of discs so as to brake the rotation of the wheel.

[0005] It has been proposed, in particular in document FR-A-2953196, to equip such braked wheels with an electromagnetic auxiliary brake ensuring energy dissipation by means other than mechanical friction.

[0006] Eddy current magnetic braking devices are also known, used for braking vehicle wheels and more particularly aircraft wheels. Document WO-A-2014 / 029962 describes such a device comprising a rotor mounted opposite an electromagnetic stator.

[0007] Document US-A-20200300310 also describes an eddy current magnetic braking device.

[0008] Conventionally, an eddy current magnetic braking device comprises a stator and a rotor that is movable in rotation in such a way that the rotor has a main face opposite a main face of the stator. The stator carries magnets emitting a magnetic flux between the main face of the stator and that of the rotor. The rotor is made of an electrically conductive material and, when the rotor is moving in front of the stator, the magnetic flux produced by the stator magnets induces eddy currents in the rotor, creating a torque opposing the rotation of the rotor.

[0009] Generally speaking, the performance of a magnetic braking device Eddy current depend on the power of the magnets used and their dimensions. The braking device is therefore relatively heavy and bulky when the maximum braking power required is high. This is the case, for example, for use on aircraft, even though mass and size are severe constraints for this use. However, the environmental constraints that apply to air transport encourage such use.

[0010] Indeed, climate change has led to the adoption of an ambitious standard, applying both to new types of aircraft but also to those currently in circulation, requiring the implementation of technological solutions in order to make them compliant with the regulations in force. Civil aviation has been mobilizing for several years now to make a contribution to the fight against climate change. To this end, the Applicant takes into consideration the factors that impact all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental impacts with the aim of improving the energy efficiency of aircraft.

[0011] One of the difficulties encountered in eddy current magnetic braking devices concerns the control of the magnetic braking device. There are currently two control modes.

[0012] In the first control mode, the stator and the rotor are mounted to move relative to each other between a free rotation position and a maximum braking position, and the braking device comprises actuators moving the stator relative to the rotor to vary the air gap between the rotor and the stator as a function of the braking setpoint.

[0013] In the second control mode, the magnets comprise electromagnets whose power supply is controlled according to the braking instruction.

[0014] Whatever the control mode chosen, its integration into the braking architecture of current aircraft proves to be relatively delicate, in particular if one wishes to optimize the braking provided by the magnetic braking device while using the control instruments conventionally available to aircraft pilots, which would make it possible to promote the use of magnetic braking devices in aircraft.

[0015] SUBJECT OF THE INVENTION

[0016] The invention aims in particular to enable simplified and optimized control of a magnetic braking device. Summary of the invention

[0017] To this end, the invention provides a method for controlling the braking of an aircraft comprising at least one control member providing a value of at least one braking control parameter, and an eddy current magnetic braking device comprising: an electronic processing unit connected to the control member, at least one stator, at least one rotor, at least one actuator for relative movement of the stator and the rotor between a remote position for minimum braking and a close position for maximum braking, magnets which are carried by the stator and which comprise electromagnets. The method comprises the following steps implemented by the electronic processing unit: - to acquire, when the aircraft is in operation, the value of the braking control parameter and the values ​​of the state parameters of the magnetic braking device; the state parameters of the magnetic braking device comprising a temperature and a supply current of the electromagnets, a temperature of the rotor, a position and a temperature of the actuator; - to determine a braking torque command from a first model which is stored in the electronic processing unit and which relates values ​​of the braking control parameter and braking torque values; - to determine an air gap setpoint and / or a supply current setpoint from at least one second model which is stored in the electronic processing unit and which relates braking torque values ​​with air gap values ​​and supply current values ​​as a function of the state parameters of the magnetic braking device.

[0018] Thus, the control of the magnetic braking device can be easily adapted according to the control members used in the aircraft (for example, cockpit control instruments). This makes it possible, for example by combining the two aforementioned actuation modes, to optimize the braking performance according to the desired braking force by acting on the speed of variation of the braking force obtained by the variation of the supply current of the electromagnets and the amplitude of the braking force obtained by the air gap.

[0019] Advantageously, the electronic processing unit is programmed to: - leave the magnetic braking device inactive as long as the value of the braking control parameter is lower than a first control threshold; - control braking only from the supply current setpoint when the value of the braking control parameter is between the first control threshold and a second control threshold greater than the first control threshold; - control braking from both the supply current setpoint and the air gap setpoint when the value of the braking control parameter is greater than the second control threshold.

[0020] According to optional characteristics, used individually or in whole or in part in combination: - the method comprises the steps of verifying that the electromagnets are in an operational state and, if not, of controlling the braking based solely on the air gap setpoint if the value of the braking control parameter is greater than the first control threshold; - the electromagnets are considered to be in the operational state when the temperature of the electromagnets is below a maximum temperature threshold and the supply current of the electromagnets is below a maximum current threshold; - the method comprises the steps of verifying that the actuators are in an operational state and, if not, of controlling the braking from only the supply current setpoint even if the value of the braking control parameter is greater than the second control threshold; - the actuators are considered to be in the operational state when the temperature of the actuators is below a maximum temperature threshold and an actuator position sensor has a voltage within an authorized range of operating voltages; - the control member comprises an instrument movable between an extreme position of no braking and an extreme position of maximum braking, the braking control parameter comprising an amplitude of movement of the control instrument between its two extreme positions.

[0021] Advantageously, the determination of the air gap setpoint and / or supply current setpoint is carried out from: - a first model which relates braking torque values ​​with supply current values ​​as a function of the state parameters of the magnetic braking device to obtain only a current setpoint and control the braking by means of the electromagnets; - a second model which relates braking torque values ​​with air gap values ​​as a function of the state parameters of the magnetic braking device to obtain only an air gap setpoint and control the braking by means of the actuators; - a third model which relates braking torque values ​​with air gap values ​​and supply current values ​​as a function of the state parameters of the magnetic braking device to obtain a current setpoint and an air gap setpoint and control the braking by means of the electromagnets and actuators.

[0022] The invention also relates to a magnetic braking device comprising at least one stator, at least one rotor, at least one actuator for relative movement of the stator and the rotor between a remote position for minimum braking and a close position for maximum braking, magnets which are carried by the stator and which comprise electromagnets, and an electronic processing unit connected to the actuator and to the electromagnets and arranged to control them by implementing this method.

[0023] The invention finally relates to an aircraft comprising such a magnetic braking device.

[0024] Other characteristics and advantages of the invention will emerge from reading the following description of a particular and non-limiting embodiment of the invention. Brief description of the drawings

[0025] Reference will be made to the accompanying drawings, among which:

[0026] [Fig-1] [Fig.l] is a partial schematic view of an aircraft equipped landing gear provided with braked wheels according to the invention;

[0027] [Fig.2] [Fig.2] is a partial schematic view of one of the wheels braked with a magnetic braking device and its communication lines with the aircraft;

[0028] [Fig.3] [Fig.3] is a functional diagram of an electronic control unit of the magnetic braking device equipping the braked wheels;

[0029] [Fig.4] [Fig.4] is a representation of the state machine implemented in the electronic control unit. DETAILED DESCRIPTION OF THE INVENTION

[0030] With reference to Figures 1 and 2, the braking system according to the invention is carried by an aircraft 100 comprising landing gears 101. Each landing gear 101 comprises a leg having one end provided with two coaxial shafts 102 on each of which a wheel 103 is mounted to pivot. Each wheel 103 comprises, in a manner known per se, a hub mounted to pivot on the shaft 102 and a rim connected to the hub by a web.

[0031] According to the invention, the wheels 103 are equipped with an eddy current magnetic braking device, generally designated 1, housed in an annular space defined between the hub and the rim.

[0032] With particular reference to [Fig.2], the magnetic braking device 1 preferably comprises at least two stators 2 and a rotor 3 arranged between the two stators 2. The stators 2 and the rotor 3 are in the form of discs, coaxial with the wheel 103, therefore having collinear central axes.

[0033] The rotor 3 has main faces each extending opposite a main face of each stator 2. The main faces of the rotor 3 are parallel to the main faces of the stators 2 which frame it and are separated from them by an air gap.

[0034] The stators 2 are linked in rotation to the shaft 102 or to the leg of the landing gear 101 while the rotor 3 is linked in rotation to the wheel 103. Thus, the rotor 3 rotates on itself around its central axis relative to the stators 2 which frame it: during this movement of the rotor 3 in a circumferential direction, the main faces of the rotor 3 remain opposite the main faces of the stators 2 and parallel to them.

[0035] The rotor 3 is made of copper or any other electrically conductive material.

[0036] Each stator 2 comprises a plurality of magnets capable of generating eddy currents in the rotor 3 when the rotor 3 pivots opposite the stator 2. The magnets here comprise permanent magnets 4 and electromagnets 5 preferably fixed on a magnetic steel support, or even on a non-magnetic support belonging to the stator.

[0037] The permanent magnets 4 are for example based on rare earths and have a magnetization vector substantially perpendicular to the main face of the stator 2, the magnets being positioned so that the magnetization vectors of two adjacent permanent magnets 4 have opposite directions. It is recalled that the magnetization vector indicates the direction of the magnetic field generated by a magnet and extends in the magnet from the South pole to the North pole.

[0038] The electromagnets 5 are positioned so as to generate a magnetic flux which either reinforces the magnetic flux produced by the permanent magnets 4, or cancels the magnetic flux produced by the permanent magnets 4. Each electromagnet 5 comprises a coil here surrounding one of the magnets 4 having a winding axis perpendicular to the main faces in such a way that each electromagnet 5 has its magnetization vector perpendicular to the main faces.

[0039] Each coil is connected to an electronic power circuit 6 controlled to circulate in said coil an electric current adjustable between extreme positive and negative values ​​so that: - when the electromagnets 5 are supplied with a non-zero current in a first direction, they generate a magnetic flux reinforcing the magnetic flux of the permanent magnets 4; - when the electromagnets 5 are supplied by a non-zero current in a second direction, they generate a magnetic flux canceling the magnetic flux of the permanent magnets 4; - when the supply current is zero, the electromagnets 5 do not generate any magnetic flux so that the magnetic flux generated by the permanent magnets 4 is not disturbed.

[0040] The electronic power circuit 6 is controlled via an electronic processing unit 7 to modify the direction of the supply current to the coils of the electromagnets 5 and the intensity of the supply current to the coils of the electromagnets 5.

[0041] Furthermore, the stators 2 are movable in translation parallel to the shaft 102 between a first minimum braking position and a second maximum braking position. In the minimum braking position, the stators 2 are distant from the rotor 3: the air gap has a maximum value such that the magnetic flux generated by the permanent magnets 4 is insufficient to produce a significant braking torque on the rotor 3 regardless of the speed of the latter. In the maximum braking position, the stators 2 are brought closer to the rotor 3: the air gap has a minimum value such that the magnetic flux generated by the permanent magnets 4 produces a maximum braking torque on the rotor 3 when the latter pivots relative to the stators 2. The stators 2 are associated with actuators 8 conventionally comprising an electric motor and a screw / nut type reducer to linearly move the stators 2 relative to the rotor 3.The actuators 8 are connected to an electronic power circuit 9 controlled by the electronic processing unit 7 to modify the supply current of the actuators 8 and move the stators 2 between their two extreme positions.

[0042] The electronic processing unit 7 comprises at least one processor and a memory containing a computer program executable by the processor. Also referring to [Fig. 3], the computer program is arranged to control the magnetic braking device 1 as a function of braking control parameters and as a function of state parameters of the magnetic braking device 1. The signals representative of the braking control parameters and of the state parameters of the magnetic braking device 1 arrive at an acquisition module 71 of the electronic processing unit 7.

[0043] The braking control parameters comprise a braking command from a control member 10 of the aircraft activated directly or indirectly by the pilot of the aircraft, and signals from at least one detector of the aircraft. The control member 10 is here more particularly a control instrument, namely for example a pedal, which is mounted in the cockpit of the aircraft to be movable by the pilot between a first extreme position of no braking, or non-pressed position, and a second extreme position of maximum braking or maximum depression position. The braking control parameter preferably comprises an amplitude of movement of the control instrument between its two extreme positions and a potentiometer is here associated with the pedal to deliver a voltage signal, between 0 and 5 V, representative of the amplitude of movement of the pedal from its first extreme position to its second extreme position. The detector whose signals are taken into account in the braking control parameters is here more particularly an air speed sensor. The signals representative of the braking control parameters pass through a braking control unit 11 of the aircraft which is connected to the electronic processing unit 7.

[0044] The state parameters of the magnetic braking device 1 include: - a current value of supply current of the electromagnets 5, - a temperature of the electromagnets 5, - a rotation speed of rotor 3 (and therefore of wheel 103), - a rotor temperature of 3, - a current air gap value, - a temperature of the actuator motors 8.

[0045] The acquisition module 71 of the electronic processing unit 7 is therefore connected to a certain number of sensors: - a sensor 12 of the supply current of the electromagnets 5, - a temperature sensor 13 such as a thermocouple mounted in one of the less than 5 electromagnets, - a sensor 14 for the rotation speed of the rotor 3, here a tachometer mounted on the shaft 102 of the wheel 103, - a temperature sensor 15 such as a thermocouple mounted in the rotor 3, - a sensor 16 for the position of the actuators 8 making it possible to determine the value air gap current (e.g. a linear sensor of the LVDT type or an angular sensor of the RVDT type or angular encoder associated with the motor output shaft), - a temperature sensor 17 such as a thermocouple mounted in the vicinity of the motor of at least one of the actuators 8.

[0046] The acquisition module preferably comprises filters to rid the received signals of any interference they contain. Here, low-pass filtering is carried out to attenuate the noise from measuring the wheel speed, for example. This filtering makes it possible to improve the robustness of the control, in particular on the components derived from the PID controllers that may be used (the cut-off frequency will be determined in a manner known per se depending on the controllers used).

[0047] The computer program executed by the electronic processing unit 7 is arranged to consolidate the braking control parameters and the state parameters of the magnetic braking device 1, then to determine an air gap setpoint and / or a supply current setpoint of the electromagnets 5 in depending on the brake control parameters and depending on the status parameters of the magnetic braking device 1.

[0048] The electronic processing unit 7 thus comprises a consolidation module 72 which implements the state machine represented in [Fig.4] to determine a braking strategy consisting of controlling the braking: - either by using only the electromagnets 5, - either by using only the actuators 8, - either by jointly using the electromagnets 5 and the actuators 8.

[0049] The consolidation module is notably arranged to gather all the data received (for example the aircraft speed coming from several aircraft computers) and possibly inhibit or set default values ​​for certain parameters in the event of a detected and confirmed failure of a sensor.

[0050] The program is arranged to verify that the electromagnets 5 are in an operational state from the values ​​of the state parameters of the magnetic braking device 1. The electromagnets 5 are considered to be in the operational state when the temperature of the electromagnets 5 is lower than a maximum temperature threshold (corresponding to the maximum operating temperature of the electromagnets 5) and the current supply current value of the electromagnets 5 is lower than a maximum current threshold (exceeding this threshold risks leading to the deterioration of the electromagnets 5, it would not be possible to control an increase in the magnetic flux supplied by the electromagnets).

[0051] The program is also arranged to verify that the actuators 8 are in an operational state from the values ​​of the state parameters of the magnetic braking device 1. The actuators 8 are considered to be in the operational state when the temperature of the motors of the actuators 8 is lower than a maximum temperature threshold (corresponding to the maximum operating temperature of the actuators 8) and the sensor 16 has a voltage included in an authorized range of operating voltages (without which it is not possible to control the actuators 8).

[0052] The state machine provides for: - leave the braking device 1 inactive (state E0) as long as the amplitude of movement of the pedal from its first extreme position to its second extreme position is less than a first control threshold here of 5% (condition cl); - control braking only from the current setpoint (state El) if the amplitude of movement of the pedal from its first extreme position to its second extreme position is between the first control threshold (i.e. 5%) and a second control threshold (here 30%) greater than the first control threshold OR if the actuators 8 are not in the operational state (condition c2); - control braking only from the air gap setpoint (state E2) if the amplitude of movement of the pedal from its first extreme position to its second extreme position is greater than the second control threshold (i.e. 30%) OR if the electromagnets 5 are not in the operational state (condition c3); - control the braking from both the current setpoint and the air gap setpoint (state E3) if the amplitude of movement of the pedal from its first extreme position to its second extreme position is greater than the second control threshold (i.e. 30%) AND if the actuators 8 and the electromagnets 5 are in the operational state (condition c4).

[0053] The state machine provides, from state El, to: - return to state E0 if the amplitude of movement of the pedal from its first extreme position to its second extreme position is less than the first control threshold (i.e. 5%) OR if the electromagnets 5 are not in the operational state (condition c5); - move to state E2 if the amplitude of movement of the pedal from its first extreme position to its second extreme position is greater than the first control threshold (i.e. 5%) AND if the electromagnets 5 are not in the operational state (condition c6); - move to state E3 if the amplitude of movement of the pedal from its first extreme position to its second extreme position is greater than the second control threshold (i.e. 30%) AND if the actuators 8 are in the operational state (condition c7).

[0054] The state machine provides, from state E2, to: - return to state E0 if the amplitude of movement of the pedal from its first extreme position to its second extreme position is less than the first control threshold (i.e. 5%) OR if the actuators 8 are not in the operational state (condition c8); - switch to state El if the amplitude of movement of the pedal from its first extreme position to its second extreme position is greater than the first control threshold (i.e. 5%) OR if the actuators 8 are not in the operational state (condition c9); - move to state E3 if the amplitude of movement of the pedal from its first extreme position to its second extreme position is greater than the second control threshold (i.e. 30%) AND if the electromagnets 5 are in the operational state (condition clO).

[0055] The state machine provides, from state E3, to: - return to state E0 if the amplitude of movement of the pedal from its first extreme position to its second extreme position is less than the first control threshold (i.e. 5%) OR if the electromagnets 5 and the actuators 8 are not in the operational state (condition cil); - switch to state El if the amplitude of movement of the pedal from its first extreme position to its second extreme position is between the first control threshold (i.e. 5%) and a second threshold (i.e. 30%) OR if the actuators 8 are not in the operational state (condition cl2); - move to state E2 if the amplitude of movement of the pedal from its first extreme position to its second extreme position is greater than the first control threshold (i.e. 5%) AND if the electromagnets 5 are not in the operational state (condition cl3).

[0056] Note that priority indexes (1), (2) and (3) are provided on certain transitions between states: - transitions between states El and E2 have a priority (1); - the transition from state El to E3 has a priority (3); - transitions between states El and E0 have a priority (2); - the transition from state E2 to E0 has a priority (2); - the transition from state E2 to E3 has a priority (3); - the transition from state E0 to E3 has a priority (1).

[0057] A transition has a higher priority the lower its priority index. Thus, priority transitions (1), for example between states E1 and E2, have priority over priority transitions (2), for example between states E1 and E0, which themselves have priority over priority transitions (3), for example from state E1 to E3, which have priority over transitions without priority, for example between state E3 and states E1 and E2.

[0058] To determine the air gap setpoint and the supply current setpoint of the electromagnets, the computer program uses at least one model which is stored in the electronic processing unit 7 and which relates braking torque values ​​with air gap values ​​and supply current values ​​as a function of the state parameters of the braking device. The model is for example an eddy current brake model obtained from digital braking simulations relating braking parameters with braking performance.

[0059] To this end, the electronic processing unit 7 comprises a module for determining a braking torque command 73 which uses a model to determine the braking torque command as a function of the amplitude of the braking torque. pedal placement. This model can be relatively simple and can be, for example, a linear control law.

[0060] The electronic processing unit 7 comprises a module for determining the air gap setpoint and the supply current setpoint 74 which here uses three models: - a first model 741 which relates braking torque values ​​with supply current values ​​of the electromagnets 5 as a function of the state parameters of the magnetic braking device 1 to obtain only a current setpoint and control the braking by means of the electromagnets 5; - a second model 742 which relates braking torque values ​​with air gap values ​​as a function of the state parameters of the magnetic braking device 1 to obtain only an air gap setpoint and control the braking by means of the actuators 8; - a third model 743 which relates braking torque values ​​with air gap values ​​and supply current values ​​of the electromagnets 5 as a function of the state parameters of the magnetic braking device 1 to obtain a current setpoint and an air gap setpoint and control the braking by means of the electromagnets 5 and the actuators 8.

[0061] These models (here of the type known as Look-up table) are based on digital simulations 744 estimating the contribution of each of the control components to the braking torque actually produced by exploiting the parameters having an impact on the braking torque produced by the state parameters of the magnetic braking device 1 such as the temperature of the rotor, the speed of the wheel, etc. These digital simulations were for example carried out in the laboratory during the design of the magnetic braking device 1.

[0062] It is understood that: model 741 is used in state El, model 742 is used in state E2, model 743 is used in state E3.

[0063] The supply current setpoint of the electromagnets 5 thus obtained is introduced at the input of a current control loop 75 providing at the output a supply current command transmitted to the electronic power circuit 6. The air gap setpoint is introduced at the input of an air gap control loop 76 providing at the output a speed / torque / position command transmitted to the electronic power circuit 9. The control loops 75, 76 are known per se and implement for example a control of one of the following types: proportional integral, fuzzy logic, state feedback control, optimal control... or any other suitable control.

[0064] The braking device according to the invention is presently also provided with an anti-lock module 77 (or anti-slip system commonly called anti-skid) to prevent or limit a locking of the wheel 103 during braking: the anti-lock module 77 releases the braking force when the speed of the wheel 103 is zero or less than a predetermined speed threshold compared to the speed of the aircraft. The anti-lock module 77 receives as input the speed of the wheel 103 and an optimal slip coefficient making it possible to determine a gain applied to the supply current control leaving the control loop 75. The anti-lock module 77 acts preferentially on the supply current control of the electromagnets because the variation in braking torque obtained by acting on the supply control of the electromagnets 5 is faster than that obtained by controlling an air gap variation by the actuators 8.For information, the expected response time for the variation of the braking torque is of the order of 50 ms. It is understood that the anti-lock is not available in state E2.

[0065] Of course, the invention is not limited to the embodiments described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0066] In particular, the magnetic braking device 1 may have a structure different from that described.

[0067] The number of rotors and / or the number of stators may be different from those mentioned.

[0068] Alternatively, the plurality of permanent magnets 4 may comprise first magnets and second magnets as follows: the first magnets have a first magnetization vector substantially perpendicular to the main face of the stator 2 and are separated two by two by a second magnet, having a second magnetization vector substantially perpendicular to the first magnetization vectors of the first two magnets between which the second magnet is located. The permanent magnets may be arranged relative to each other in a Halbach pattern and have identical or different dimensions (the first magnets having a width, measured parallel to the main face, greater than the width of the second magnets; and the first magnets optionally having a length, measured parallel to the main face, greater than the length of the second magnets).The electromagnets 5 are preferably arranged around the first magnets.

[0069] The invention can be used with a braking device comprising only electromagnets.

[0070] The actuators 8 can be hydraulic cylinders controlled by solenoid valves.

[0071] The device described is axial flow but the invention is applicable to a function radial flow operation (with tubular drums instead of discs) or operation combining axial and radial flow.

[0072] Optionally, the rotor 3 has a thickness such that a skin effect (otherwise called a skin effect or Kelvin effect) is generated from each face of the rotor 3 over more than half of the thickness of the rotor 3 at least over a range of possible relative speeds of the rotor 3 with respect to the stators 2. The eddy currents generated from the two faces will then circulate in the central part of each rotor 3, which will increase the braking torque. This results in a “superposition of the skin effects”, the thickness of the rotor 3 being sufficiently small to obtain this effect while satisfying the thermal and mechanical constraints.

[0073] The control member may be different from a pedal and comprise, for example, a hand-operated lever, or an automatic landing assistance device or any other computer which would issue a deceleration command used to activate the braking device.

[0074] The operational state corresponds to nominal operation. Among the parameters that can be used to determine the operational state of the electromagnet and / or the actuator are the state of the communication bus with the control / power electronics associated with each of these (interruption, drop in flow rate, etc.), the detection of a blockage of the actuator (increase in the actuator supply current but no movement detected), etc.

[0075] Preferably, the program of the electronic processing unit 7 is arranged to allow modification of the different thresholds, either by an operator in the factory or during a maintenance operation, or automatically during operation, for example by taking into account a particular event (temperature of the landing runway, weather conditions, etc.).

[0076] It will be noted that below a certain rotational speed of the rotor 3, the braking torque is negligible regardless of the power supply to the electromagnets 5. It will then be necessary to consider an additional brake also serving as a parking brake. The magnetic braking device according to the invention can thus be associated with a conventional friction braking device which comprises friction members, for example a stack of carbon discs, and a plurality of electromechanical actuators carried by an actuator holder.

Claims

Claims

1. Method for controlling the braking of an aircraft comprising at least one control member (11) providing a value of at least one braking control parameter, and an eddy current magnetic braking device (1) comprising: an electronic processing unit (7) connected to the control member (11), at least one stator (2), at least one rotor (3), at least one actuator (8) for relative movement of the stator (2) and the rotor (3) between a remote position for minimum braking and a close position for maximum braking, magnets which are carried by the stator and which comprise electromagnets (5); the method comprising the following steps implemented by the electronic processing unit (7): - to acquire, when the aircraft is in operation, the value of the braking control parameter and the values ​​of state parameters of the magnetic braking device (1); the state parameters of the magnetic braking device (1) comprising a temperature and a supply current of the electromagnets (5), a temperature of the rotor (7), a position and a temperature of the actuator (8); - to determine a braking torque command from a first model which is stored in the electronic processing unit (7) and which relates values ​​of the braking control parameter and braking torque values; - to determine an air gap setpoint and / or a supply current setpoint from at least one second model which is stored in the electronic processing unit (7) and which relates braking torque values ​​with air gap values ​​and supply current values ​​as a function of the state parameters of the magnetic braking device (1).

2. Method according to claim 1, in which the electronic processing unit (7) is programmed to: leave the magnetic braking device (1) inactive as long as the value of the braking control parameter is less than at a first control threshold; - controlling the braking only from the supply current setpoint when the value of the braking control parameter is between the first control threshold and a second control threshold greater than the first control threshold; - controlling the braking from both the supply current setpoint and the air gap setpoint when the value of the braking control parameter is greater than the second control threshold.

3. Method according to claim 2, comprising the steps of verifying that the electromagnets (5) are in an operational state and, if not, of controlling the braking from only the air gap setpoint if the value of the braking control parameter is greater than the first control threshold.

4. A method according to claim 3, wherein the electromagnets (5) are considered to be in the operational state when the temperature of the electromagnets (5) is below a maximum temperature threshold and the supply current of the electromagnets (5) is below a maximum current threshold.

5. Method according to any one of claims 2 to 4, comprising the steps of verifying that the actuators (8) are in an operational state and, if not, of controlling the braking from only the supply current setpoint even if the value of the braking control parameter is greater than the second control threshold.

6. A method according to claim 5, wherein the actuators (8) are considered to be in the operational state when the temperature of the actuators is below a maximum temperature threshold and a position sensor of the actuators (8) has a voltage within an allowed range of operating voltages.

7. Method according to any one of the preceding claims, in which the determination of the air gap setpoint and / or supply current setpoint is carried out from: - a first model (741) which relates braking torque values ​​with current values supply according to the state parameters of the magnetic braking device (1) to obtain only a current setpoint and control the braking by means of the electromagnets (5); - a second model (742) which relates braking torque values ​​with air gap values ​​according to the state parameters of the magnetic braking device (1) to obtain only an air gap setpoint and control the braking by means of the actuators (8); - a third model (743) which relates braking torque values ​​with air gap values ​​and supply current values ​​according to the state parameters of the magnetic braking device (1) to obtain a current setpoint and an air gap setpoint and control the braking by means of the electromagnets (5) and the actuators (8).

8. Method according to any one of the preceding claims, in which the control member (10) comprises an instrument movable between an extreme position of no braking and an extreme position of maximum braking, the braking control parameter comprising an amplitude of movement of the control instrument (10) between its two extreme positions.

9. Eddy current magnetic braking device (1), comprising at least one stator (2), at least one rotor (3), at least one actuator (8) for relative movement of the stator (2) and the rotor (3) between a remote position for minimum braking and a close position for maximum braking, magnets which are carried by the stator (2) and which comprise electromagnets (5), and an electronic processing unit (7) connected to the actuator (8) and to the electromagnets (5) and arranged to control them by implementing the method according to any one of the preceding claims.

10. Aircraft comprising a magnetic braking device (1) according to claim 9 and at least one landing gear (101) in which the magnetic braking device (1) is housed.

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