Aircraft provided with emergency landing-gear extension means

Abstract

The invention relates to an aircraft landing-gear system (100, 200, 300), comprising actuators associated with the landing gear and supplied with pressurized hydraulic fluid by a hydraulic circuit (10; 15), the hydraulic circuit including at least uplock boxes (106, 109, 206, 209, 306, 309) for the hatches and the landing gear, the aircraft comprising emergency extension means (20) capable of ensuring release of the hatches and of the landing gear in order to cause the landing gear to extend under the effect of gravity in the event of failure of the hydraulic circuit. According to the invention, the emergency extension means comprise a pyrotechnic device (50) suitable for generating, in a controlled manner, pressurized gas that acts on a first face of a piston (40) which slides in a sealed manner inside a chamber (30) such that a second face of the piston, in contact with the hydraulic fluid, transmits the pressure of the gas thus produced at least to the uplock boxes via the hydraulic fluid.

Description

[0001] DESCRIPTION

[0002] TITLE OF THE INVENTION: AIRCRAFT EQUIPPED WITH LANDING RESORT EXTENSION MEANS

[0003] The present invention relates to the field of aeronautics.

[0004] BACKGROUND OF THE INVENTION

[0005] We know of aircraft equipped with a landing gear comprising one or more landing gear, and more particularly aircraft equipped with a hydraulic circuit with a main source of hydraulic pressure supplying various actuators, including operating cylinders for said landing gear, operating cylinders for hatches, latching boxes to lock the landing gear in the retracted position and the hatches in the closed position...

[0006] Safety considerations dictate that aircraft be equipped with emergency extension systems capable of opening hatches and extending landing gear in the event of a failure of the aircraft's hydraulic system, and in particular its pressure source, for example, following the loss of an engine. These emergency extension systems can take various forms:

[0007] - An auxiliary pressure source capable of pressurizing the hydraulic circuit, replacing the main pressure source. This auxiliary pressure source could, for example, be an electric pump, which assumes that a power supply can be maintained even when the aircraft is operating under degraded conditions. The auxiliary source could also be a hydraulic accumulator, although the pressurized gas is susceptible to leaks, requiring regular monitoring and refilling. These solutions are complex and bulky;

[0008] - Electric actuators capable of supplementing the hydraulic actuators to at least release the hatches and landers, so that they can deploy by gravity. This arrangement is complex and also requires that a power supply can be ensured under already degraded operating conditions;

[0009] - A pneumatic pressure source in the form of a pressurized gas cylinder capable of injecting pressurized gas into the hydraulic circuit to pressurize it sufficiently to allow the hatches to open and the landers to be released. However, such technology requires regular monitoring and refilling of the cylinder, and necessitates a complete purging of the hydraulic fluid each time these pneumatic means are used.

[0010] SUBJECT OF THE INVENTION

[0011] The invention aims in particular to provide simple, easy-to-maintain emergency extension means that do not require significant power for their operation.

[0012] SUMMARY OF THE INVENTION

[0013] To this end, an aircraft landing system is proposed, comprising actuators associated with the landing gear and supplied with pressurized hydraulic fluid by a hydraulic circuit, including at least hatch and landing gear attachment boxes, the aircraft having emergency extension means capable of ensuring the release of the hatches and landing gear to cause the extension of the landing gear under the effect of gravity in the event of failure of the aircraft's hydraulic circuit, characterized in that these emergency extension means include a pyrotechnic device adapted to generate pressurized gas in a controlled manner acting on a first face of a sliding piston sealed in a chamber so that a second face of the piston in contact with the hydraulic fluid transmits the pressure of the gas thus produced at least to the attachment boxes via the hydraulic fluid.

[0014] Thus, the pyrotechnic device can be activated by a simple electrical pulse, requiring minimal power. This pulse can, for example, be generated by the aircraft's batteries. The pyrotechnic device requires no monitoring or maintenance other than the regular replacement of the cartridge(s). The separation performed by the piston between the gas produced by the pyrotechnic device and the hydraulic fluid prevents contamination of the latter by the gas, thereby eliminating the need for a complete purging of the hydraulic circuit each time the emergency extension equipment is used.

[0015] Preferably, the pyrotechnic device includes one or more gas-generating cartridges adapted to generate pressurized gas in response to an electrical impulse.

[0016] Preferably, the emergency extension means include a cylinder in which is made the chamber in which the piston is mounted to slide tightly, the cylinder having an inlet port to receive the pyrotechnic device and admit the gas on the first face of the piston, and an outlet port for its connection to the hydraulic circuit so that the hydraulic fluid comes into contact with the second face of the piston.

[0017] Preferably, the backup extension means include a level sensor to detect the presence of hydraulic fluid in the chamber in which the piston slides.

[0018] Preferably, the emergency extension means include a relief valve to drain the gas from the chamber after the pyrotechnic device has been triggered. In a preferred embodiment, the hydraulic circuit to which the emergency extension means are connected is an auxiliary hydraulic circuit adapted to supply at least the lashing boxes, such that the second face of the piston is in contact with the fluid in the auxiliary hydraulic circuit.

[0019] Preferably, the auxiliary hydraulic circuit defines a closed volume of fluid, with the piston left mobile in the chamber against a spring element acting on the first face of the piston to absorb expansions of the fluid contained in the auxiliary hydraulic circuit.

[0020] Preferably, the auxiliary hydraulic circuit is connected to a main hydraulic circuit equipped with a main pressure source to ensure the filling of the auxiliary hydraulic circuit with hydraulic fluid.

[0021] Preferably, the hydraulic circuit to which the emergency extension means are connected is a main hydraulic circuit equipped with a main pressure source and adapted to supply the landing gear actuators whose attachment boxes, so that the second face of the piston is in contact with the fluid in the main hydraulic circuit.

[0022] Preferably, the main hydraulic circuit includes a non-return valve preventing pressurization of the main pressure source when the backup extension means are activated.

[0023] Other features and advantages of the invention will become apparent from the following description of a particular and non-limiting embodiment of the invention.

[0024] BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Reference will be made to the attached drawings, among which: [Fig. 1] Figure 1 is a schematic view of landing gear and associated actuators equipping an aircraft; [Fig. 2] Figure 2 is a schematic view of part of an emergency hydraulic circuit of the aircraft supplying pressurized fluid to some of the actuators of Figure 1, equipped with emergency extension means according to a preferred embodiment of the invention of which only the cylinder forming the pressurization chamber has been drawn in detail, the rest of the circuit being schematic;

[0026] [Fig. 3] Figure 3 is a schematic view analogous to Figure 2 in which the emergency extension means are associated with a main hydraulic circuit of the aircraft according to a variant of the invention.

[0027] DETAILED DESCRIPTION OF THE INVENTION As illustrated in Figure 1, the invention is described herein in relation to an aircraft comprising two main landing gear 100, 200 and one auxiliary landing gear 300. The main landing gear 100, 200 are operated by cylinders 105, 205 to be deployed or retracted into bays closed by hatches 107, 207 actuated by cylinders 108, 208. The main landing gear 100, 200 are held in the retracted position by latching housings 106, 206, while the hatches are held closed by latching housings 109, 209. The main landing gear 100, 200 are equipped with wheels 101, 201, themselves equipped with brakes 102, 202.

[0028] The auxiliary landing gear 300 is operated by a hydraulic cylinder 305 to be deployed or retracted into a compartment closed by hatches 307 actuated by hydraulic cylinders 308. The auxiliary landing gear 300 is held in the retracted position by a latching housing 306, while the hatches are held closed by a latching housing 309. The auxiliary landing gear 300 also includes a steering cylinder 310 adapted to orient its wheels to steer the aircraft on the ground. This landing gear configuration is given for illustrative purposes only and does not in any way limit the possibility of applying the invention to other configurations.

[0029] These actuators are normally supplied with pressurized hydraulic fluid by a main hydraulic circuit of the aircraft which includes a main pressure source, such as a pump driven by one of the aircraft's engines.

[0030] According to a preferred embodiment illustrated in Figure 2, an auxiliary hydraulic circuit 15 supplies the coupling boxes 106, 109, 206, 209, 306, 309 with pressurized fluid in place of the main hydraulic circuit in the event of a failure of the latter (in particular of its main pressure source), for example via shuttle valves (not shown). Alternatively, it is possible to extend the separation between the two hydraulic circuits to the coupling boxes 106, 109, 206, 209, 306, 309, by providing separate backup actuators on these boxes, supplied by the auxiliary hydraulic circuit 15 and capable of actuating the coupling boxes in place of the actuators supplied by the main hydraulic circuit.

[0031] The auxiliary hydraulic circuit 15 is preferably filled with hydraulic fluid from the aircraft's main hydraulic circuit. This filling is carried out under very low pressure, lower than the actuation pressure of the lashing mechanisms. Alternatively, filling can also be carried out via a manual system. A check valve 60 retains the fluid in the auxiliary hydraulic circuit 15, thus enclosing the fluid in a sealed volume. The auxiliary hydraulic circuit 15 includes a safety valve 16 to protect it from potential overpressures, primarily due to the expansion of the fluid within the sealed volume of the auxiliary hydraulic circuit 15. The activation pressure of the safety valve 16 must, of course, be higher than the activation pressure of the lashing mechanisms.

[0032] The invention aims to generate sufficient pressure in the hydraulic fluid of the auxiliary hydraulic circuit 15 to enable the actuation of the latching boxes in order to allow the release of the hatches and the landing gear so that they can extend under the effect of gravity to their deployed position, even if the pressure source of the main hydraulic circuit were to fail.

[0033] As illustrated in Figure 2, the auxiliary hydraulic circuit 15 is, according to the invention, equipped with emergency extension means 20. These means comprise a chamber 30 formed within a cylinder 31 in which a piston 40 is mounted for sealed sliding. A pyrotechnic device 50 is arranged on the chamber 30 to generate, in a controlled manner, pressurized gas (illustrated by small dots) in the portion 30a of the chamber 30 so as to act on a first face 41 of the piston 40. The pyrotechnic device 50 preferably comprises one or more removable pyrotechnic cartridges 51, preferably arranged in a manner easily accessible to maintenance personnel. A second face 42 of the piston 40 is in direct contact with the hydraulic fluid (illustrated by small horizontal lines) of the auxiliary hydraulic circuit 15.For this purpose, the cylinder 31 has an inlet port 32 to receive the pyrotechnic device 50 and allow the action of the gas on the first face 41 of the piston 40 and an outlet port 33 for its connection to the auxiliary hydraulic circuit 15, allowing the arrival of the hydraulic fluid in the part 30b of the chamber 30 in contact with the second face 42 of the piston 40.

[0034] When the pyrotechnic device 50 is not triggered, the piston 40 is in equilibrium in the chamber 30 due to the pressure of the hydraulic fluid exerted on the second face 42 and the action of a spring element 34 acting on the first face 41. The piston 40 is thus free to move in the chamber 30 to absorb the expansions of the fluid volume in the auxiliary hydraulic circuit 15. A level sensor 35 ensures that there is fluid in the part 30b of the chamber 30 connected to the auxiliary hydraulic circuit 15.

[0035] In the event of a failure of the main hydraulic circuit's pressure source, preventing normal operation of the latching mechanisms, the pyrotechnic device 50 is triggered to generate pressurized gas in chamber 30, acting on the first face 41 of piston 40. The pyrotechnic device 50 is preferably triggered by a control 52 in the form of a simple electrical pulse, delivered either by pilot action or by logic implemented by the onboard computers in response, for example, to the detection of a hydraulic failure. The pressure of the gas thus generated is transmitted via piston 40 to the hydraulic fluid, without the gas contaminating the hydraulic fluid.The pressure thus delivered by the pyrotechnic device 50 is calibrated to cause the actuation of the hooking boxes 106, 109, 206, 209, 306, 309 in order to allow the release of the hatches and the landers so that they can extend under the effect of gravity to their deployed position.

[0036] Section 30a of chamber 30 is equipped with a gas relief valve 36, which is calibrated to open automatically when the latches have been actuated, thus venting the gas from chamber 30 and bringing this section of the chamber to atmospheric pressure. This allows maintenance personnel to change the pyrotechnic cartridge 51 without residual overpressure. Once the new pyrotechnic cartridge 51 is installed, the relief valve 36 is operated to close it. Alternatively, the relief valve 36 remains closed and is only opened by maintenance personnel when the pyrotechnic cartridge 51 is replaced.

[0037] Activating the emergency extension means 20 requires only a brief electrical pulse 52 to activate the pyrotechnic device 50. This pulse can be generated using the aircraft's batteries.

[0038] Furthermore, the maintenance of the emergency extension means is limited to the regular replacement of the pyrotechnic cartridge(s) 51. The physical separation provided by the piston 40 between the pressurized gas and the hydraulic fluid eliminates any need to purge the auxiliary hydraulic circuit in the event of the activation of the emergency extension means.

[0039] The emergency extension means 20 are here associated with an auxiliary hydraulic circuit 15 specially dedicated to the emergency actuation of the hooking boxes.

[0040] According to a variant illustrated in Figure 3, the emergency extension means 20 can be directly connected to the main hydraulic circuit 10, which normally supplies the landing gear maneuvering actuators and is equipped with a main hydraulic pressure source 11, for example, a pump driven by one of the aircraft's engines. In the event of a failure of this main source, the emergency extension means 20 are used to apply sufficient pressure to the fluid in the main circuit to actuate at least the docking mechanisms. A check valve 60 prevents the main hydraulic pressure source 11 from being pressurized by the emergency extension means 20 when they are activated. This variant does not require an auxiliary hydraulic circuit.

[0041] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0042] In particular, the hydraulic circuit may have a different structure than described and incorporate more or fewer components.

[0043] Thus, although here we have illustrated only one pyrotechnic device for the entire hydraulic circuit of the aircraft, it is possible to plan for several pyrotechnic devices on the same circuit.

[0044] If an auxiliary hydraulic circuit is planned, an auxiliary hydraulic circuit can be planned for each landing gear, each with its own pyrotechnic device.

Claims

DEMANDS 1. Aircraft landing gear system (100, 200, 300), comprising actuators, associated with the landing gear and supplied with pressurized hydraulic fluid by a hydraulic circuit (10; 15), including at least one set of attachment housings (106, 109, 206, 209, 306, 309) for the landing gear and hatches, the system comprising emergency extension means (20) capable of releasing the hatches and landing gear to cause the landing gear to extend under the effect of gravity in the event of a failure of the hydraulic circuit, characterized in that these emergency extension means comprise a pyrotechnic device (50), adapted to generate pressurized gas in a controlled manner, acting on a first face of a piston (40) sliding in a sealed chamber (30) such that a second face of the piston in contact with the hydraulic fluid transmits the pressure of the gas thus produced at least to the mounting boxes (106, 109, 206, 209, 306,309) via the hydraulic fluid, the emergency extension means being connected to an auxiliary hydraulic circuit (15) adapted to supply at least the latching boxes (106, 109, 206, 209, 306, 309), so that the second face of the piston is in contact with the fluid in the auxiliary hydraulic circuit, the auxiliary hydraulic circuit (15) defining a closed volume of fluid, the piston (40) being left mobile in the chamber (30) against a spring element (34) acting on the first face of the piston to absorb expansions of the fluid contained in the auxiliary hydraulic circuit.

2. Lander system (100, 200, 300) according to claim 1, wherein the pyrotechnic device (50) comprises one or more pyrotechnic gas-generating cartridges (51) adapted to generate pressurized gas in response to an electrical pulse.

3. Landing system (100, 200, 300) according to claim 1, in which the emergency extension means comprise a cylinder (31) in which is formed the chamber (30) in which the piston (40) is mounted to slide tightly, the cylinder comprising an inlet port (32) for receiving the pyrotechnic device (50) and admitting the gas on the first face of the piston, and an outlet port (33) for its connection to the hydraulic circuit so that the hydraulic fluid comes into contact with the second face of the piston.

4. Landing system (100, 200, 300) according to claim 3, wherein the emergency extension means comprise a level sensor (35) for detecting the presence of hydraulic fluid in the chamber (30) in which the piston (40) slides.

5. Landing system (100, 200, 300) according to claim 3, wherein the emergency extension means comprise a discharge valve (36) for draining the gas into the chamber (30) after triggering the pyrotechnic device (50).

6. Landing system (100, 200, 300) according to claim 1, wherein the auxiliary hydraulic circuit (15) is connected to a main hydraulic circuit (10) equipped with a main pressure source (11) to ensure the filling of the auxiliary hydraulic circuit (15) with hydraulic fluid.

7. Landing system (100, 200, 300) according to claim 1, wherein the main hydraulic circuit includes a check valve (60) preventing pressurization of the main pressure source (11) when the emergency extension means (20) are activated.

8. Aircraft comprising a landing gear system (100, 200, 300) according to any one of the preceding claims.

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