FR3059418A1 - LIQUID STORAGE SYSTEM COMPRISING AN INTEGRATED GAUGE ENCLOSURE, AND AIRCRAFT - Google Patents

Abstract

The present invention relates to a storage system (10) which is provided with an envelope (15) delimiting an internal space (12) for containing a liquid (14), said envelope (15) comprising an inner wall (16). A gauging device (30) comprises at least two flexible capacitive sensors (31) each secured to said inner wall (16), each capacitive sensor (31) emitting a signal (33) representing a level of said liquid in a detection zone of this capacitive sensor (31), said capacitive sensors (31) being distant from each other.

Description

© Publication number: 3,059,418 (only to be used for reproduction orders) © National registration number: 16,01685 ® FRENCH REPUBLIC

NATIONAL INSTITUTE OF INDUSTRIAL PROPERTY

COURBEVOIE © Int Cl ⁸ : G 01 F23 / 26 (2017.01), B 64 D 37/02

A1 PATENT APPLICATION

©) Date of filing: 29.11.16. © Applicant (s): AIRBUS HELICOPTERS — RR. (© Priority: @ Inventor (s): LOLLINI LIONEL, BORNES SYLVAIN and COULONDRES GAUTIER. (43) Date of public availability of the request: 01.06.18 Bulletin 18/22. ©) List of documents cited in the report preliminary research: Refer to end of present booklet (© References to other national documents ® Holder (s): AIRBUS HELICOPTERS. related: ©) Extension request (s): (© Agent (s): GPI & ASSOCIES.

(64) STORAGE SYSTEM FOR LIQUID INCLUDING AN INTEGRATED GAUGE ENVELOPE, AND AIRCRAFT.

FR 3,059,418 - A1 (67) The present invention relates to a storage system (10) which is provided with an envelope (15) delimiting an internal space (12) intended to contain a liquid (14), said envelope (15 ) comprising an internal wall (16). A gauging device (30) comprises at least two flexible capacitive sensors (31) each secured to said internal wall (16), each capacitive sensor (31) emitting a signal (33) representing a level of said liquid in a detection zone of this capacitive sensor (31), said capacitive sensors (31) being distant from each other.

Liquid storage system comprising an integrated gauge casing, and aircraft

The present invention relates to a liquid storage system comprising an integrated gauge casing, a vehicle provided with this tank, and the gauging method applied. In particular, the storage system may include a fuel tank.

The invention relates to the field of fuel gauging systems, and in particular to vehicle gauging systems. Such a vehicle can in particular be an aircraft, and possibly a rotorcraft.

A vehicle having a fuel engine usually comprises a tank containing fuel intended for this engine. In addition, the vehicle may include a gauging system for measuring the quantity of fuel contained in the tank, namely the mass and / or the volume of the fuel contained.

A first gauging system is provided with a float connected to a position sensor.

A second gauging system includes an ultrasonic system with an ultrasonic transmitter and receiver.

A third gauging system includes an optical system.

A fourth gauging system includes a capacitive probe. An aircraft capacitive probe used to assess a quantity of fuel is conventionally known as a “gauging rod”.

A gauging rod is thus inserted into a tank containing fuel and air. The gauging rod comprises a capacitor provided with two metallic armatures. For example, the gauging rod has two concentric metal tubes which respectively form an outer frame surrounding an inner frame. The outer frame and the inner frame are radially separated from each other by an internal space.

In addition, the external frame is provided with at least one opening for communicating the internal space of the gauging rod with the interior of the tank. When the gauging rod is submerged in a tank containing fuel, this fuel enters the internal space via the openings in the external frame.

The electrical capacity of the capacitor varies according to the dielectric permittivity of the medium present in the internal space. This dielectric permittivity therefore depends on the dielectric permittivity of the fuel in the submerged part of the gauging rod and on the dielectric permittivity of the air above this submerged part. The dielectric permittivity of a fuel being much higher than the dielectric permittivity of air, the dielectric permittivity of the medium present in the internal space of the gauging rod varies appreciably when the level of fuel between the armatures varies.

Thus, when the level of fuel between the plates of the capacitor varies, the dielectric permittivity of the medium present in the internal space of the gauging rod varies, and therefore the electrical capacity of the gauging rod varies. The height of the fuel present between the metal reinforcements of the gauging rod can then be deducted from this electrical capacity.

To this end, the capacitor can be supplied electrically by an alternating electric current to emit a level signal which is a function of the electrical capacity of the capacitor, and therefore of the fuel level.

The volume of fuel present in the tank can then be deduced from this level signal according to various parameters. On an aircraft, a mathematical relation can for example give this volume of fuel as a function of the geometry of the tank, of the angle of pitch of the aircraft, of the angle of roll of the aircraft, and of accelerations undergone by the aircraft. The fuel mass is obtained from the fuel volume and the density of the fluid used.

The gauging rods mounted in the usual tanks have sufficient accuracy with regard to regulatory requirements.

However, depending on the location of the gauging rod and the geometry of the tank, the measurements made by a gauging rod may have degraded precision for certain inclinations in roll and / or in pitching of the tank. A risk of under-gauging or over-gauging is possible with certain tanks and with particular attitudes of this tank.

According to another aspect, as a gauging rod comprises capacitive probes immersed in the tank, each gauging rod is adapted to a particular tank, in particular in terms of fixing in the tank as well as according to the shape of the tank. In addition, each new gauging rod must then be certified by the aeronautical authorities concerned in order to meet safety criteria and measurement accuracy.

In particular, a gauging rod with metal tubes must not damage the tank in the event of a crash. Thus, the tubes of a gauging rod can have a fusible zone intended to break in the event of a crash to reduce the risks of perforation of the tank.

In addition, the arrangement of a gauging rod in a flexible tank can be tricky. Without particular provision, a flexible tank can tend to deform, and risks damaging for example a gauging rod arranged in the tank.

The document FR2672389 describes a gauging system provided with optical sensors.

The document FR2892508 describes a capacitive gauge which is provided with a measurement capacitor as well as a reference capacitor and a standard capacitor.

Document FR2908511 describes a gauging system comprising means indicative of the height of liquid, means indicative of the pitch angle of the tank and / or means indicative of the roll angle of the tank. A calculator calculates the volume of liquid as a function of a predetermined relationship having as parameters at least said height as well as said pitch angle and / or said roll angle.

The object of the present invention is therefore to propose a storage system for containing a liquid, and in particular fuel, this storage system comprising a gauging device tending to limit the risks of over-gauging or under-gauging.

According to the invention, a storage system is provided with an envelope delimiting an internal space intended to contain a liquid, this envelope comprising an internal wall facing the internal space, the storage system comprising a gauging device for estimating the amount of liquid in the envelope.

The gauging device comprises at least two flexible capacitive sensors each secured to said internal wall, each capacitive sensor emitting a signal representing a level of said liquid in a detection zone of this capacitive sensor, said capacitive sensors being distant from each other.

For example, at least three flexible capacitive sensors are each secured to said internal wall, each capacitive sensor emitting a signal representing a level of said liquid in a detection zone of this capacitive sensor, said capacitive sensors being distant from each other.

The detection zone of a capacitive sensor is advantageously distinct from the detection zone of another capacitive sensor.

Optionally, the gauging device comprises a computer connected to each capacitive sensor to make a first estimate of said quantity as a function of said signals.

The term "joined" means that a capacitive sensor is placed in or against the internal wall. A capacitive sensor is thus for example either an integral part of a tank envelope, or carried by the internal wall.

Optionally, the first estimate can be made based on said signals only. The expression "based on said signals only" means that the signals emitted by the capacitive sensors represent the only variables used to determine the amount of liquid, namely the volume and / or mass of the liquid. These variables are injected into a mathematical model by the computer to deduce the quantity of liquid.

This mathematical model can take various forms such as a database providing information on the quantity of liquid as a function of the measurements made by the capacitive sensors, a mathematical law, a series of operations performed by the computer ...

In this context, the gauging device includes capacitive sensors which equip an envelope. Such an envelope can represent a tank pre-equipped with several flexible capacitive sensors.

Such capacitive sensors can for example be of the type known under the brand Kapflex®, or described in document WO 2009/122061 for example.

A capacitive sensor can have the advantage of being traversed by a low intensity electric current. Consequently, such a sensor can be arranged in or near a fuel. In addition, the flexibility of the capacitive sensor also allows it to be folded and therefore to be integrated into a flexible envelope. In addition, these capacitive sensors prove to be light which makes it possible to arrange several without considerably weighing down the storage system.

In addition, an electrical power supply and transmission of measured data equips one end of each capacitive sensor. The beams are then connected to a computer. This calculator comprises a subset of electrical power transmission and a calculator for calculating the level of liquid in the envelope.

Consequently, each capacitive sensor has an electrical capacity which varies as a function of the height of the liquid near this capacitive sensor. When the height of the liquid in the envelope varies, the electrical capacity of the capacitive sensor varies, and the electrical signal transmitted by the capacitive sensor to the computer varies. A capacitive sensor therefore has a mode of operation similar to the operation of a gauging rod.

By providing at least two capacitive sensors on the envelope itself, the gauging device makes it possible to estimate the position of the surface plane of the liquid from measurements made by all of the capacitive sensors, possibly only with these measurements, and d '' deduct the amount of liquid. The surface plane represents the surface of the liquid in contact with the ambient air in the internal space. Such a liquid surface plane is called a "level line" for convenience and by analogy with a swimming pool water line for example.

A rotorcraft often has a relatively small roll angle. Consequently, by arranging two capacitive sensors distant from each other along the roll axis, the invention can make it possible to obtain relatively precise results.

The measurement signals emitted by the capacitive sensors may be sufficient for calculating the volume and / or the mass of the liquid contained in the envelope. The use of pitch and roll angle measurements as well as accelerations is no longer imperative. On a vehicle, the data of the attitude of the vehicle, its acceleration or engine data are no longer essential because the measurements from the capacitive sensors arranged on or in the internal wall become necessary and possibly sufficient by themselves for calculate the volume and / or mass of the liquid on board. Optionally, the gauging device may include a compensator or a density sensor for deducing the mass of the liquid from the volume of liquid.

By using at least three capacitive sensors, the accuracy of the gauging device is increased. The estimated current position of the surface plane is therefore more precise.

By using at least four capacitive sensors, the failure detection of a capacitive sensor is facilitated which makes it possible to secure the gauging device.

Compared to a system using a gauging rod, the invention can have various advantages.

Indeed, an envelope can be pre-equipped with flexible capacitive sensors. Therefore, the arrangement of the gauging device on a vehicle is made easier.

In addition, the capacitive sensors can be integrated into the enclosure. This possible integration of the capacitive sensors in a tank addition itself makes it possible to mount the storage system on a table. The bottles marked out by the envelope can be delivered already equipped with a part of the gauging device. Such a method is absolutely not possible with a gauging rod which risks on the one hand to perforate and / or damage the tank due to its rigidity and, on the other hand, to be itself damaged in because of its rigidity.

These advantages lead to a saving of time in the assembly line of a vehicle, and an optimization of the costs of the storage system.

Furthermore, the arrangement of at least two or even at least three capacitive sensors on or in the internal wall as such, and not in the middle of the internal space, can significantly improve the accuracy of the estimation of the amount of liquid.

According to another aspect, the use of flexible capacitive sensors can tend to reduce the risks of perforation of the envelope in the event of an accident, with regard to a system provided with rigid gauging rods.

In addition, the storage system can be devoid of a plate carrying a gauging rod.

Furthermore, the gauging device optionally includes a display connected to the computer. This display allows you to display the value of the estimated quantity of liquid.

This quantity can take the form of a volume of the liquid possibly expressed in liter (s), or even of a mass possibly expressed in kilogram (s).

The storage system may further include one or more of the following features.

Thus, the envelope can be flexible, the envelope being reversibly foldable by an operator to be mounted in a tank compartment or unfolded to be extracted from said tank compartment.

The envelope can thus represent a flexible flexible tank equipped with gauges, namely capacitive sensors. The invention can in fact make it possible to equip a flexible tank outside of a vehicle, unlike rod solutions which present risks of perforation for example.

According to another aspect, the internal wall possibly comprising several faces, two adjacent faces joining at a corner of the envelope, at least one of said sensors can be arranged on a corner.

The capacitive sensors are thus distributed, for example, in the corners of the envelope to optimize the measurement of the quantity of liquid. This arrangement tends to reduce the risk of over-gauging or under-gauging.

According to another aspect, the envelope possibly comprising a bottom surmounted by the inner wall, at least one of the capacitive sensors can be secured to the bottom and to said inner wall.

A tank usually has a substantially planar bottom, a lateral internal wall which extends in elevation from the bottom and a substantially planar ceiling. A capacitive sensor of the invention can thus extend in elevation on the internal wall and on the bottom.

Thus, the bottom of the envelope can also be equipped with flexible capacitive sensors.

By arranging a capacitive sensor on the bottom of the envelope and on its internal wall, the invention can make it possible to measure the level line of the liquid, even when the envelope has angles of attitude which usually makes a good measurement difficult.

The installation of capacitive sensors in the bottom of the tank therefore makes it possible to refine the measurements.

According to another aspect, at least one of said capacitive sensors can be embedded in said internal wall, and possibly if necessary in the bottom of the envelope.

Some capacitive sensors do not necessarily need to be in contact with the liquid to measure a height of this liquid. Such a capacitive sensor can thus be integrated into the envelope, being arranged between two layers of the envelope, at least locally.

Alternatively or additionally, the envelope comprises at least one fixing system for a capacitive sensor, this fixing system holding the associated capacitive sensor against the internal wall in a predetermined position.

The envelope comprises, for example, as many fixing systems as there are capacitive sensors, each fixing system fixing a single capacitive sensor against the internal wall. A fixing system can guarantee the absence of folds of the capacitive sensor on itself, and of course a good reading of the liquid level.

A fixing system can for example comprise a guide integral with the internal wall in which the capacitive sensor is slid. As an example of assembly, each corner of a tank envelope is equipped with a slide, each capacitive sensor being slid in a slide.

Another alternative or complementary fastening system may include at least one link, for example a link provided with a loop and hook system. According to one embodiment, an upper fixing system and a lower fixing system hold a capacitive sensor in position. The upper fixing system and the lower fixing system then ensure that the capacitive sensor is maintained possibly in a strict vertical position when the enclosure is mounted in a compartment.

According to another aspect, the storage system that can comprise a first measurement unit for measuring at least one angle of roll or of pitching of the envelope, the storage system that can comprise a second measurement unit for measuring at least one acceleration of the envelope, the first measurement unit and the second measurement unit are for example connected to the computer. Therefore, the computer can perform at least one verification of the first estimate using said at least one roll or pitch angle and said at least one acceleration, the computer being connected to an alert system to generate a alert based on at least one predetermined criterion applied during said verification.

The storage system can estimate the amount of liquid contained in the envelope by using the capacitive sensors, and for example only the capacitive sensors.

On the other hand, the attitude angles and the accelerations undergone by the envelope can be used to check the accuracy of the first estimate. For example, a verification calculation made from the first estimate of the quantity of liquid associated with the acceleration and the attitude of the helicopter in real time must lead to results which correspond to those obtained by the capacitive sensors. . For example, the position within the envelope of a surface plane of the liquid is determined using capacitive sensors and verification calculation. If a difference between the two positions does not belong to a previously established margin of error, the gauging device deduces therefrom the presence of an error in the measurements made by the capacitive sensors.

According to another aspect, an aircraft can be provided with a storage system according to the invention, in particular for containing fuel.

The invention also relates to a method for gauging an amount of liquid in a storage system according to the invention.

This process includes the following steps:

- measurement of information relating to a height of liquid with each of said capacitive sensors, each capacitive sensor providing information relating to a height of liquid in a measurement area of said internal space,

- determination of a first estimate of the quantity of liquid using said information and a predetermined mathematical model.

The expression "measurement of information relating to a height" refers to the signal emitted by a capacitive sensor, this signal varying as a function of said height.

Each capacitive sensor thus emits a signal relating to the level of the liquid near this capacitive sensor. The gauging device calculator then processes the signals received to estimate the quantity of liquid through a mathematical model, this mathematical model being able to be qualified as the first mathematical model for convenience. The first mathematical model thus makes it possible to deduce the amount of liquid from the information transmitted by the capacitive sensors, with regard to the geometry of the envelope.

This first mathematical model can take various forms such as a database providing the current position of the liquid as a function of the measurements made by the capacitive sensors, a mathematical law, a series of operations performed by the calculator ...

The step of determining said first estimate may include the following steps:

- estimation of a current position of a surface plane in which the surface of said liquid is contained in said envelope using said measured heights and a predetermined mathematical model,

- determination of said first estimate using said current position and a predetermined mathematical model.

For example, each capacitive sensor emits an electrical signal at an electrical voltage which varies as a function of the height of the liquid near the capacitive sensor. The computer deduces therefrom height information used to determine the position of the surface plane known as the "current position".

During a first calculation, the computer is then able to estimate the position of the surface plane of the liquid on board in the envelope. The architecture of the envelope deployed in the vehicle being recorded in a memory unit of the computer, a second calculation then makes it possible to estimate with the same precision the volume and / or the mass of the liquid via a predetermined mathematical model. This predetermined mathematical model can be called "second mathematical model". In addition, the second mathematical model can take various forms such as a database providing information on the quantity of liquid as a function of the current position of the liquid, a mathematical law, a series of operations performed by the calculator ...

Furthermore, the method can include the following verification steps:

- measure at least a roll or pitch angle of the envelope,

- measure at least one acceleration of the envelope,

- determination of a theoretical position of the surface plane using said at least one measured roll or pitch angle as well as said at least one measured acceleration.

By way of example, the capacitive sensors make it possible to estimate that the surface plane is in a current position in the aircraft reference system and that the envelope contains 300 liters of fuel.

During the verification step, the computer determines a theoretical position of the surface plane reached by a fuel volume of 300 liters with the measured roll and / or pitch angle and the measured accelerations. This calculation can be carried out using a predetermined and stored mathematical model. For example, the surface plane in the theoretical position has a non-zero angulation with the current position which can possibly mean the presence of a malfunction.

If the acceptable margin of error is respected, the avionics system of the helicopter therefore benefits from a more secure measurement of the fuel level than that obtained by the prior art because it will have been not only calculated but verified by an algorithm additional.

According to an alternative, if a difference between said current position and said theoretical position is not included in a predetermined range of measurements, the method may include a step of issuing an alert.

The difference can be estimated in different ways, for example across an angle and / or a distance.

According to the example, if said inclination is not present in the memorized range, an alert is generated.

Alternatively or additionally, if a difference between said current position and said theoretical position is not within a predetermined range of measurements, the method may include a step of searching for a malfunction for each capacitive sensor.

According to the example, if said inclination is not present in the stored range, a step of searching for a malfunction is implemented for each sensor.

This step of looking for a malfunction can for example be undertaken if the gauging device comprises more than two capacitive sensors, or even more than three capacitive sensors.

The step of finding a malfunction of a capacitive sensor may include the following steps:

- measurement of information relating to a height of liquid with each of the capacitive sensors not the subject of the verification step,

- estimation of an alternative position of a surface plane of said liquid in the envelope using said liquid heights measured with each of the capacitive sensors not the subject of the verification step

- if a difference between said alternative position and said theoretical position is not included in said predetermined range of measurements, the capacitive sensor being the subject of the verification step is considered to be defective.

According to this variant, an additional step is implemented to estimate which capacitive sensor is malfunctioning. If the gauging device makes it possible to make an estimate of the correct quantity of fuel without using a particular capacitive sensor, the gauging device indicates that this capacitive sensor was at the origin of the problem encountered.

In addition, the measurements from the capacitive sensors can for example be used to estimate the attitude of a vehicle, and determine if these estimates are correlated with the avionics system of the vehicle.

The invention and its advantages will appear in more detail in the context of the description which follows with examples given by way of illustration with reference to the appended figures which represent:

FIG. 1, a diagram showing a storage system,

FIG. 2, a diagram showing a capacitive sensor arranged on an internal wall and a bottom,

FIG. 3, a diagram illustrating various organs of the gauging device, and

- Figure 4, a diagram illustrating the process applied by the invention.

The elements present in several separate figures are assigned a single reference.

Three directions X, Y and Z orthogonal to each other are shown in some figures.

The first direction X is said to be longitudinal. The term "longitudinal" relates to any direction parallel to the first direction X. A roll axis of the envelope shown may be parallel to this first direction

The second direction Y is said to be transverse. The term "transverse" relates to any direction parallel to the second direction Y. A pitch axis of the envelope shown can be parallel to this second direction Y.

Finally, the third direction Z is said to be in elevation. The expression "in elevation" relates to any direction parallel to the third direction Z. A yaw axis of the envelope shown may be parallel to this third direction Z.

Figure 1 shows a storage system 10 according to the invention. This storage system 10 is intended to contain a liquid 14, such as fuel supplying an engine 5 for example. The storage system 10 can for example be arranged on a vehicle, and in particular on an aircraft 1. Such an aircraft 1 can in particular be a rotorcraft.

The storage system 10 is provided with a tank 11. This tank 11 can be arranged in a tank compartment 2 of a vehicle.

The reservoir 11 comprises an envelope 15 which delimits an internal space 12. For this purpose, the envelope 15 comprises multiple walls. For example, the casing 15 is provided with a wall called the “internal wall 16” which extends in elevation from a bottom 17 towards a top 18.

The internal wall 16 faces laterally from the internal space. This internal wall 16 can comprise several faces 161 to laterally delimit the internal space 12. Two adjacent faces 161 join for example by forming a corner 162 of the envelope 15.

The internal space 12 is then delimited in elevation by the bottom 17 and the top 18. For example, the top 18 is substantially planar. The bottom 17 may have several inclined facets directed towards a low point of the envelope 15. Optionally, the storage system 10 comprises a fuel plate 20 at this low point. Such a fuel plate 20 can comprise, for example, a drain valve, a purge valve, a pump 21, a pipe 22 directed to an engine

5 ....

Therefore, a liquid 14 and a gas 13 can be contained in the internal space 12. The interface surface between the gas 13 and the liquid 14 is called the surface plane 100 for convenience. Such a gas 13 can be air, the envelope possibly comprising a usual venting system.

In this context, the envelope 15 can be made with a rigid material, for example plastic. However, the envelope can be flexible in the form of a flexible skin. The envelope 15 can thus be folded to be introduced into the tank compartment 2, or to be extracted outside this tank compartment 2.

Furthermore, the storage system 10 comprises a gauging device 30 for estimating the quantity of liquid 14 contained in the envelope 15. This quantity can be expressed in the form of a mass or a volume.

The gauging device 30 comprises at least two capacitive sensors 31, and for example two or at least three or even at least four capacitive sensors 31. These capacitive sensors are flexible, unlike a gauging rod, and can therefore be if necessary folded on themselves.

Each capacitive sensor 31 is moreover secured at least to the internal wall 16. For example, at least one capacitive sensor 31 or even all the capacitive sensors 31 extend vertically along a corner 162 of the internal wall 16.

According to the first variant of FIG. 1, the capacitive sensors are only integral with the internal wall 16.

On the other hand, according to the second variant of FIG. 2, at least one of the capacitive sensors 31 or even all the capacitive sensors are secured to the bottom 17 and to the internal wall 16. This arrangement can optimize the gauging when the surface plane is in a position 101 or when this surface plane touches the bottom, for example with a small quantity of liquid and a non-negligible roll or pitch angle Ω.

Regardless of the variant and with reference to FIG. 1, at least one of the capacitive sensors 31 can be secured to the internal wall 16 or even to the bottom 17, by being embedded in this internal wall 16 or even to the bottom 17.

According to another approach, the casing 15 can be equipped with at least one fixing system 35 which is fixed to the internal wall 16 or even to the bottom 17. A fixing system 35 makes it possible to hold the capacitive sensor 31 against the internal wall , or even against the bottom, in a predetermined position. A fastening system 35 can for example take the form of a link or a slide. By way of illustration, an upper fixing system 36 as well as a lower fixing system 37 or even at least one intermediate fixing system 38 hold in position a capacitive sensor 31 against the side wall.

According to another aspect, the capacitive sensors 31 are distant from each other. Each capacitive sensor 31 then emits a signal 33 relating to the height of the liquid 14 in a predetermined detection zone of this capacitive sensor 31.

With reference to FIG. 3, the gauging device 30 comprises a computer 40 for processing these signals 33. For example, the computer 40 comprises a unit which is fixed to the fuel plate 20 and connected to each capacitive sensor by links 32 .

The calculator 40 can comprise for example a processor, an integrated circuit, a programmable system, a logic circuit, these examples not limiting the scope given to the expression "calculator".

By way of illustration, the computer 40 may include at least one processor 42 communicating with a memory unit 43. The memory unit 43 may include one or more memory modules for example.

In addition, the computer 40 can include input / output interfaces 41. For example, input interfaces are connected to the capacitive sensors 31 to receive information relating to the height of the liquid at various measurement points, for example in the form of an electrical voltage.

Likewise, input interfaces can be connected to a first measurement unit 60 which measures at least a roll or pitch angle of the envelope. Such a first measurement unit 60 can take the form of an inertial unit, of inclinometers, etc. The first measurement unit 60 then transmits to the computer information relating to a roll angle and / or a pitch angle of the 'envelope.

Input interfaces can be connected to a second measurement unit 70 which measures at least one acceleration of the envelope 15. Such a second measurement unit 70 can take the form of accelerometers ... The second measurement unit 70 transmits for example to the computer information relating to an acceleration along a pitch axis of the envelope, and / or an acceleration along a roll axis of the envelope, and / or an acceleration along a yaw axis of the envelope .

In addition, the gauging device 30 may include a display 50 and an alert system 80 integrated into the computer 40 or in communication with the computer via wired or non-wired links and output interfaces.

A display 50 can for example comprise a screen displaying the quantity of liquid. An alert system 80 may include a visual, audible or even tactile alert means for generating an alert.

Consequently, the computer injects the information received into at least one mathematical model, to deduce the amount of liquid therefrom or even to generate an alert if a malfunction is detected.

Each mathematical model used can take various forms such as a database providing data according to input information, a mathematical law, a series of operations performed by the calculator ...

In particular, the computer makes a first estimate of the quantity of liquid contained in the envelope as a function of the signals 33 emitted by the capacitive sensors 31. In addition, the computer checks the first estimate using the roll angle and / or of the measured pitch angel (s) and of each measured acceleration, the computer 40 generating an alert as a function of at least one predetermined criterion applied during said verification.

Figure 4 illustrates the process that can be applied.

During a first measurement step STP1, each capacitive sensor 31 measures information relating to a height of the liquid in a measurement area of the associated internal space of the capacitive sensor.

During a step of estimating the amount of liquid STP2, the computer 40 determines a first estimate of the amount of liquid using the information from the capacitive sensors 31 and a predetermined mathematical model.

For example, during a preliminary step STP 2.1, the computer 40 estimates the position of the surface plane 100, called "current position" for convenience. A first mathematical model taking into account the geometry of the envelope 15 makes it possible to determine this current position using at least two pieces of liquid height information given by said at least two capacitive sensors 31.

During a step of calculating the first STP estimate

2.2, the computer 40 calculates the first estimate by injecting the current position into a second predetermined mathematical model. The second mathematical model can be predetermined based on the geometry of the envelope.

Optionally, the computer 40 can then implement verification steps to verify the first estimate.

During a second measurement step STP3, the first measurement means 60 estimates a roll and / or pitch angle of the envelope.

During a third measurement step STP4, the second measurement means 70 estimates at least one acceleration of the envelope.

During an intermediate stage STP5, the computer determines a theoretical position of the surface plane 100 by injecting into a third mathematical model the first estimate, the angle of roll and / or the angel of pitch measured, and each measured acceleration .

The third mathematical model can be predetermined based on the geometry of the envelope.

During an STP6 consistency verification step, the computer determines whether a difference between the current position and the theoretical position is within a predetermined range of measurements.

If so, no malfunction is detected and the quantity of liquid can be displayed on the display during a first display step STP7.

If not, a step of issuing an alert is implemented. For example, the calculator communicates with the display to display the quantity of liquid corresponding to the first estimate. However, the computer communicates with the alert system to generate an alert.

Optionally and in particular in the presence of at least three or four capacitive sensors, during a step of searching for an STP8 malfunction, the computer tests the capacitive sensors one after the other.

For each capacitive sensor tested, the computer 40 requests a measurement of information relating to a height of liquid with each of the capacitive sensors 31 not being the subject of the test. Consequently, the computer estimates an alternative position of the surface plane 100 in the envelope 15 using these heights.

If a difference between the alternative position and said theoretical position is not included in said predetermined range of measurements, the capacitive sensor 31 being tested is considered to be defective.

Optionally and during a step of estimating a minimum quantity STP9, the computer 40 determines the quantity of liquid using the alternative position inducing the smallest quantity of liquid.

This quantity of liquid is then displayed on the display during a second STP10 display step, at the same time as an alert is generated.

Naturally, the present invention is subject to numerous variations as to its implementation. Although several embodiments have been described, it is understood that it is not conceivable to identify exhaustively all the possible modes. It is of course conceivable to replace a means described by an equivalent means without departing from the scope of the present invention.

Claims (16)

1. Storage system (10) provided with an envelope (15) delimiting an internal space (12) intended to contain a liquid (14), said envelope (15) comprising an internal wall (16) facing said internal space ( 12), said storage system (10) comprising a gauging device (30) for estimating the quantity of liquid (14) contained in the envelope (15), characterized in that said gauging device (30) comprises at least two flexible capacitive sensors (31) each secured to said internal wall (16), each capacitive sensor (31) emitting a signal (33) representing a level of said liquid in a detection zone of this capacitive sensor (31), said capacitive sensors (31) being distant from each other. 2. Storage system according to claim 1, characterized in that said gauging device (30) comprises at least three flexible capacitive sensors (31) each secured to said internal wall (16), said capacitive sensors (31) being spaced apart each other. 3. Storage system according to any one of claims 1 to 2, characterized in that said envelope (15) is flexible, said envelope (15) being reversibly foldable by an operator to be mounted in a tank compartment (2 ) or unfolded to be extracted from said tank compartment (2). 4. Storage system according to any one of claims 1 to 3, characterized in that said internal wall (16) comprising several faces (161), two adjacent faces (161) meeting at a corner (162) of the envelope (15), at least one of said capacitive sensors (31) is arranged on a corner (162). 5. Storage system according to any one of claims 1 to 4, characterized in that said envelope (15) comprising a bottom (17) surmounted by said internal wall (16), at least one of said capacitive sensors (31) is secured to the bottom (17) and said internal wall (16). 6. Storage system according to any one of claims 1 to 5, characterized in that at least one of said capacitive sensors (31) is embedded in said internal wall (16). 7. Storage system according to any one of claims 1 to 5, characterized in that said envelope (15) comprises at least one fixing system (35) for a capacitive sensor (31), this fixing system (35) maintaining the capacitive sensor (31) associated against the internal wall (16) in a predetermined position. 8. Storage system according to any one of claims 1 to 7, characterized in that said gauging device (30) comprises a computer (40) connected to each capacitive sensor (31) to make a first estimate of said quantity in function of said signals (33). 9. Storage system according to claim 8, characterized in that said storage system (10) comprising a first measurement unit (60) for measuring at least a roll or pitch angle of the envelope, said storage system (10) comprising a second measurement unit (70) for measuring at least one acceleration of the envelope (15), said first measurement unit (60) and said second measurement unit (70) are connected to the computer (40) , said computer (40) performing at least one verification of the first estimate using said at least one roll or pitch angle and said at least one acceleration, said computer (40) being connected to an alert system (80) to generate an alert based on at least one predetermined criterion applied during said verification. 10. Aircraft (1) provided with a storage system (10), characterized in that said storage system (10) is according to any one of claims 1 to 9. 11. Method for gauging an amount of liquid in a storage system (10), characterized in that the storage system (10) being according to any one of claims 1 to 10, said method comprises the following steps: - measurement of information relating to a height of liquid with each of said capacitive sensors (31), each capacitive sensor (31) providing information relating to a height of liquid in a measurement area of said internal space (12), - determination of a first estimate of the quantity of liquid using said information and a predetermined mathematical model. 12. Method according to claim 11, characterized in that the step of determining said first estimate comprises the following steps: - estimation of a current position of a surface plane (100) in which the surface of said liquid (14) is contained in said envelope (15) using said measured heights and a predetermined mathematical model, - determination of said first estimate using said current position and a predetermined mathematical model. 13. Method according to claim 12, characterized in that said method comprises the following verification steps: - measure at least a roll or pitch angle of the envelope - measure at least one acceleration of the envelope (15), - determination of a theoretical position of said surface plane (100) using said at least one measured roll or pitch angle as well as said at least one measured acceleration. 14. Method according to claim 13, characterized in that, if a difference between said current position and said theoretical position is not included in a predetermined range of measurements, said method comprises a step of issuing an alert. 15. Method according to any one of claims 13 to 14, characterized in that, if a difference between said current position and said theoretical position is not included in a predetermined range of measurements, the gauging device comprising at least three capacitive sensors said method comprises a step of searching for a malfunction for each capacitive sensor (31). 16. Method according to claim 14, characterized in that said step of searching for a malfunction of a capacitive sensor (31) comprises the following steps: - measurement of information relating to a height of liquid with each of the capacitive sensors (31) not the subject of the verification step, - estimation of an alternative position of a surface plane (100) of said liquid in the envelope (15) using said liquid heights measured with each of the capacitive sensors (31) not the subject of the step of verification, - if a difference between said alternative position and said theoretical position is not included in said predetermined range of measurements, the capacitive sensor (31) subject to the verification step is considered to be defective. 112