Device for activating an emergency function of a landing gear

Abstract

The invention relates to a device (100) for activating an emergency function for the deployment of the landing gear of an aircraft, wherein the device comprises: an electric motor; a screw (120) configured to be translated by the electric motor between an extended position and a retracted position, and configured to disengage a holding element that keeps the landing gear in the closed position when it is in the extended position, and to secure the holding element that keeps the landing gear in the closed position when it is in the retracted position; two magnetic field sensors (151, 152); and a finger (160) that comprises a permanent magnet (165) at one of its ends, and which is capable of moving between the two magnetic field sensors, driven by the screw in such a way that the permanent magnet aligns with the magnetic field sensors.

Description

[0001] Description

[0002] Title of the invention: Device for activating a landing gear emergency function

[0003] Technical Field

[0004] The present invention relates to the general field of aircraft landing gear, and more particularly to an electromechanical actuator capable of implementing an emergency function for deploying the landing gear.

[0005] Prior art

[0006] In the aeronautical field, the locking of an aircraft landing gear is generally ensured by a mechanical actuating device (known by the English term "Up-Lock") intended to support the weight of the landing gear during the flight phase of the aircraft by means of a hook and without any other additional source of energy.

[0007] To unlock the landing gear and allow it to deploy, a first hydraulic cylinder is arranged so as to detach said hook from the mechanical actuating device. However, if the integrity of the first hydraulic cylinder is affected or if it finds itself in a non-operational state, i.e. broken down, a second hydraulic cylinder (known as a "Freefall") replaces the first hydraulic cylinder to perform this same function. The use of the second cylinder therefore constitutes an emergency measure (or function) operated by the pilot of the aircraft.

[0008] However, to facilitate maintenance of the second hydraulic cylinder and thus ensure the implementation of this emergency function, it is preferable to replace it with another type of actuator offering the same level of reliability and availability, while minimizing costs. For example, we want to avoid the use of complex electronic circuitry to control this new actuator. In addition, with the rise of hybrid and / or electric aircraft, it is preferable to replace the second hydraulic cylinder with an electric or electromechanical actuator.

[0009] It is therefore desirable to have a new device for activating this emergency function that allows the second hydraulic cylinder to be replaced by an electromechanical actuator with the same levels of reliability and availability, while minimizing costs.

[0010] Statement of the invention

[0011] The invention relates to a device for activating an emergency function for deploying the landing gear of an aircraft, comprising:

[0012] - an electric motor;

[0013] - a screw configured to be driven in translation by the electric motor between an extended position and a retracted position and configured to detach an element for holding the landing gear in the closed position when it is in the extended position and to secure said element for holding the landing gear in the closed position when it is in the retracted position;

[0014] - two magnetic field sensors; and

[0015] - a finger comprising a permanent magnet at one of its ends and capable of moving between the two magnetic field sensors by driving with the screw so that the permanent magnet is opposite the magnetic field sensors.

[0016] The activation device according to the invention proposes activation of the emergency function of the landing gear without a hydraulic circuit and without software for controlling the deployment of the landing gear. It is the position of the finger facing the two magnetic field sensors which makes it possible to control the direction of rotation of the electric motor and therefore the position of the screw. Indeed, in the extended position, the screw makes it possible to detach (uncouple or unlock) the holding element, for example a hook, from the landing gear in the closed position so as to deploy the landing gear; while in the retracted position, the landing gear remains locked, which means that the holding element is integral with the landing gear or coupled to the landing means or in the so-called locked position.

[0017] According to a particular characteristic of the invention, the electric motor is a brushed motor.

[0018] This simplifies the drive system, as a brushed motor does not require additional components compared to a brushless motor. A brushless motor requires the development and use of control electronics.

[0019] According to another particular characteristic of the invention, the screw is a ball screw, a roller screw or a screw with trapezoidal threads.

[0020] The ball screw has the advantage of having a very good efficiency, around 96%, and therefore allows the size of the electric motor to be reduced; while a trapezoidal screw will require a more powerful electric motor, but will be less expensive.

[0021] According to another particular characteristic of the invention, the activation device comprises two reduction stages.

[0022] According to another particular characteristic of the invention, the activation device comprises a stop at the rear of the screw so as to block its translation when placed in the retracted or extended position.

[0023] It should be noted that in the case of a ball screw, there may be two stops at the rear so as to block its translation whether in the retracted or extended position.

[0024] According to another particular characteristic of the invention, the two magnetic field sensors are Hall effect sensors.

[0025] According to another particular characteristic of the invention, the activation device comprises a fixed connector intended to connect the electric motor to a power supply. According to another particular characteristic of the invention, the activation device comprises a first transistor and a first diode, in parallel with the first transistor, connected to one of the two magnetic field sensors and to the electric motor, and a second transistor and a second diode, in parallel with the second transistor, connected to the other magnetic field sensor and to the electric motor.

[0026] Thanks to transistors, electric motor control is simplified. Depending on the position of the finger, that is, facing the first or second magnetic field sensor, the transistors will be in the open or closed position, which allows the electric motor to be powered or not to be able to move the screw between the extended and retracted positions. In addition, depending on the voltage, in particular the polarity, supplied to the transistors, the motor will rotate in one direction or the other. In other words, thanks to transistors, the two magnetic field sensors act as a switch on a transistor when the finger, in particular the permanent magnet, is facing one or the other.

[0027] Another subject of the invention is an aircraft comprising a landing gear and a device for activating an emergency function of said landing gear according to the invention.

[0028] According to a particular characteristic of the invention, the aircraft comprises an emergency power supply configured to electrically power the electric motor of said activation device.

[0029] Thus, the device of the invention does not require a particular power supply to operate, since it can be powered by the aircraft's emergency or basic power supply. This power supply is, for example, +14 V, or +28 V or even +36 V.

[0030] Brief description of the drawings

[0031] Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate exemplary embodiments thereof without any limiting character. [Fig. 1] Figure 1 represents, schematically and partially, a side section of the activation device according to one embodiment of the invention.

[0032] [Fig. 2] Figure 2 represents, schematically and partially, the device of Figure 1 according to a section from above.

[0033] [Fig. 3] Figure 3 shows, schematically and partially, an electrical circuit controlling the electric motor and the position of the finger according to one embodiment of the invention.

[0034] Description of the embodiments

[0035] Figures 1 and 2 represent, schematically and partially, a section of the activation device 100 according to an embodiment of the invention in side view for Figure 1 and in top view for Figure 2.

[0036] The device 100 includes an electric motor 110 which is electrically powered by a power supply via a fixed electrical connector 180.

[0037] The electric motor 110 can also be electrically powered via an electric cable connected to a power supply with or without a cable gland system.

[0038] The electric motor 110 is for example a brushed motor, because this makes it possible to reduce the number of components of the device 100. However, the motor 110 can also be a brushless motor.

[0039] The device 100 comprises a screw 120 driven in translation by the electric motor 110. The screw 120 can move between a retracted position and an extended position. In the extended position, it will be able to unlock the hook (or the up-lock) which holds the landing gear to deploy the landing gear.

[0040] During the translation of the screw 120, it drives a finger 160 which will move between two magnetic field sensors 151 and 152. Other types of sensors can of course be envisaged such as “switch” type sensors.

[0041] The finger 160 comprises at its end, opposite the sensors 151, 152, a permanent magnet 165. The sensors 151, 152 detect the magnetic field generated by the permanent magnet 165 when the latter (and therefore the finger 160) is opposite the sensor 151, 152 detecting this magnetic field.

[0042] The finger 160 is mechanically held to the screw 160. For example, the finger 160 is fixed to the screw 120 by gluing, screwing or welding.

[0043] The sensors 151, 152 are for example Hall effect sensors.

[0044] When the screw 120 is in the retracted position, the finger 160 and its permanent magnet 165 are opposite the sensor 151; whereas when the screw 120 is in the deployed or extended position, the finger 160 and its magnet 165 are opposite the sensor 152. The position of the finger 160 and its magnet 165 opposite one of the sensors 151, 152 makes it possible to serve as a switch in the circuit 300 of FIG. 3 to electrically power or not the electric motor 100, thanks to the detection of the magnetic field, generated by the magnet 165, by the sensors 151, 152.

[0045] In this embodiment, the device 100 comprises two reduction stages. A pinion 141 is fixed to the rotor 112 of the electric motor 110 and constitutes, with the wheel of the shaft 140, the first reduction stage. The second reduction stage consists of the pinion of the shaft 140 which meshes with the wheel of the nut 130 of the screw 120. These two reduction stages make it possible to increase the torque between the electric motor 10 and the screw 120.

[0046] These two reduction stages can be replaced by an elliptical type reducer, which makes it possible to have only one reduction stage and therefore to reduce the mass and volume of the device 100. As an example, such a reducer exists commercially under the name “Harmonie drive ®”.

[0047] The two reduction stages can still be removed and the 130 nut replaced as a motor rotor.

[0048] The 120 screw is advantageously a ball screw, but can also be a screw with trapezoidal threads.

[0049] A stop 122 may also be present to stop the screw 120 when it is in the retracted or extended position. An anti-rotation 135 may also be present to allow the nut 130 to transmit a torque which is transformed into a thrust force at the screw 120. This thrust force is an additional force to unlock the hook locking the landing gear.

[0050] The device 100 may also comprise an electronic card 170 on which the two magnetic field sensors 151, 152 are soldered and on which the electrical circuit 300 of FIG. 3 may be implemented.

[0051] Figure 3 shows, schematically and partially, an electrical circuit 300 which makes it possible to control the electric motor 110 and the position of the screw 120 and therefore of the finger 160 according to one embodiment of the invention.

[0052] Each transistor 171, 172 is in the open position when the finger 160 and its permanent magnet 165 are opposite the sensor 151 or 152 detecting the magnetic field generated by the magnet 165.

[0053] When the finger 160 is therefore in front of the sensor 152, the latter opens the transistor 172. The transistor 172 therefore does not allow the electric current to pass through it; while the transistor 171 is closed and therefore allows the electric current to pass because the sensor 151 does not detect any magnetic field.

[0054] By applying a positive electrical voltage V, for example + 28 V, to the connector 180, an electrical current will be able to flow through the diode 182, the electric motor 110 and the transistor 171. The electric motor 110 being supplied positively, it will rotate the reducer, formed by the pinion 141, the shaft 140 and the nut 130, and translate the screw 120 into the extended position to unlock the hook holding the landing gear. The finger 160 will therefore also move towards the sensor 151.

[0055] When the finger 160 and the magnet 165 reach the sensor 151, the latter opens the transistor 171, which blocks the passage of the electric current through the diode 181. This therefore stops the translation of the screw 120 which then remains in the extended position. The landing gear of the aircraft is therefore deployed, because the element holding the landing gear in the closed (non-deployed) position, here the hook, is now detached (or unlocked) from a mechanical actuating device intended to support the weight of the landing gear during the flight phase of the aircraft.

[0056] In order for the screw 120 to return to the retracted position, a negative voltage V, for example - 28 V, is applied to the connector 180. The electric current will be able to flow through the diode 181, the electric motor 110 and the transistor 172. The transistor 172 is now closed because the sensor 152 no longer detects the magnetic field generated by the magnet 165 since the finger 160 is no longer in front of the sensor 152.

[0057] Due to the negative voltage, the electric motor 110 rotates in the opposite direction and therefore retracts the screw 120 so that it returns to the retracted position. When the finger 160 and the magnet 165 are in front of the sensor 152, the latter will open the transistor 172 again, thus blocking the passage of electric current through the electric motor 110 by the effect of the diode 181. The device for activating the emergency function for deploying the landing gear is thus reset.

[0058] Thus the device for activating the emergency deployment function of the invention can be activated and controlled simply using the polarity of the voltage applied to the terminals of the electric motor 110; and the sensors 151 and 152 are used as electrical stops and allow the device to be actuated. It does not require any software or complex electronics to be controlled and activated.

[0059] Diodes 301 and 302 may also be present to protect the device against lightning and to be able to discharge the electric current from the coils of the motor 110.

[0060] Current limiters 161, 162 can also be added to prevent thermal effects and variations in electrical voltage of the electrical network supplying the device of the invention.

Claims

Claims

1. Aircraft comprising a landing gear and a device (100) for activating an emergency function for deploying the landing gear, comprising: - an electric motor (110); - a screw (120) configured to be driven in translation by the electric motor between an extended position and a retracted position and configured to detach an element for holding the landing gear in the closed position when it is in the extended position and secure said element for holding the landing gear in the closed position when it is in the retracted position; - two magnetic field sensors (151, 152); and - a finger (160) comprising a permanent magnet (165) at one of its ends and capable of moving between the two magnetic field sensors by driving with the screw so that the permanent magnet is opposite the magnetic field sensors.

2. An aircraft according to claim 1, wherein the electric motor is a brushed motor.

3. An aircraft according to any one of claims 1 or 2, wherein the screw is a ball screw, a roller screw or a trapezoidal thread screw.

4. An aircraft according to any one of claims 1 to 3, comprising two reduction stages.

5. Aircraft according to any one of claims 1 to 4, comprising a stop (122) at the rear of the screw so as to block its translation when placed in the retracted or extended position.

6. An aircraft according to any one of claims 1 to 5, wherein the two magnetic field sensors are Hall effect sensors.

7. An aircraft according to any one of claims 1 to 6, comprising a fixed connector (180) for connecting the electric motor to a power supply.

8. An aircraft according to any one of claims 1 to 7, comprising a first transistor (171) and a first diode (181), in parallel with the first transistor, connected to one of the two magnetic field sensors (151) and to the electric motor, and a second transistor (172) and a second diode (182), in parallel with the second transistor, connected to the other magnetic field sensor (152) and to the electric motor.

9. An aircraft according to any one of claims 1 to 8, comprising an emergency power supply configured to electrically power the electric motor of said activation device.

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