Pressure sensor with conductive ink deposited on a deformable surface, and aircraft comprising such a sensor

Abstract

Pressure sensor with conductive ink deposited on a deformable wall, and aircraft comprising such a sensor. The present invention relates to a pressure sensor (10) comprising: - a deformable wall (14) under the effect of pressure; - a magnetic circuit (16) deposited on the deformable wall (14), the circuit (16) having an impedance varying according to the deformation of the wall (14); - an electronic estimation device (18) comprising a measurement module (40) for the impedance of the magnetic circuit and a calculation module (42) for an estimated pressure value from the measured impedance; the magnetic circuit (16) being formed by a conductive ink deposited on the deformable wall (14). Figure for the abstract: Figure 1

Description

Title of the invention: Pressure sensor with conductive ink deposited on a deformable surface, and aircraft comprising such a sensor

[0001] The invention relates to a pressure sensor, as well as an aircraft comprising such a pressure sensor.

[0002] The present invention relates to the field of mono and multifunction anemobaroclinometric probes (static pressure, total pressure, angle of attack, etc.).

[0003] The field of application of the invention is in particular aeronautics.

[0004] US document 8,707,793 B2 describes a pressure sensor comprising two coils and a magneto-elastic deformation element.

[0005] However, this solution is based on the interaction between the two coils, one of which is wound around the deformation element. Thus, the system is not mechanically stable and may be sensitive to mechanical vibrations, increasing measurement uncertainties.

[0006] There is therefore a need for a stable, compact and robust pressure sensor, of simple design, intended for use in the aeronautical field, pressure - whether internal or external to the aircraft - being an important factor to ensure the proper functioning and safety of aircraft.

[0007] To this end, the invention relates to a pressure sensor, comprising:

[0008] - a wall that deforms under the effect of pressure;

[0009] - a magnetic circuit deposited on the deformable wall, the circuit having a impedance varying according to the deformation of the wall;

[0010] - an electronic estimation device comprising a measurement module the impedance of the magnetic circuit and a calculation module for an estimated pressure value from the measured impedance;

[0011] the magnetic circuit being formed by a conductive ink deposited on the deformable wall.

[0012] Thus, with the sensor according to the invention, the conductive ink track printed on the membrane of the deformable element and forming the magnetic circuit makes it possible to retrieve static or total pressure information that is relatively insensitive to measurement errors. The system is therefore less sensitive to mechanical stresses while maintaining good accuracy. Furthermore, the presence of a single conductive ink track increases the compactness and mechanical strength of the sensor.

[0013] According to other advantageous aspects of the invention, the pressure sensor comprises one or more of the following features, taken individually or in any technically possible combination:

[0014] - the pressure sensor comprises a housing having several walls defining an internal volume subject to pressure variation, the deformable wall being formed by one of the walls of the casing;

[0015] - the deformable wall has, from its center, an alternation of hollows and bumps in the form of undulations with respect to a horizontal median plane, parallel to a surface of the deformable wall on which the conductive ink is deposited;

[0016] - when the measured pressure is an internal pressure within the casing, the conductive ink is deposited on the bumps; and 1

[0017] when the measured pressure is an external pressure to the housing, the conductive ink is deposited on the hollows;

[0018] - the magnetic circuit is in the shape of a spiral, and each convolution of the circuit magnetic defines a loop;

[0019] the magnetic circuit preferably comprising at least 10 turns;

[0020] - the spiral formed by the magnetic circuit is in the shape of a boustrophedon;

[0021] - the spiral is crenellated;

[0022] - the wall is deformable from a pressure variation greater than about ten of pascals;

[0023] the wall preferably being resistant to a pressure of up to 2400 pascals; and

[0024] - the calculation module is configured to calculate the estimated pressure value from of a predetermined law defining a relationship between impedance and pressure;

[0025] said law being preferably obtained from a predefined set of pairs of a measured pressure value and an associated impedance value.

[0026] The invention also relates to an aircraft comprising a pressure sensor as defined above.

[0027] The invention will become clearer upon reading the following description, given solely by way of non-limiting example, and made with reference to the drawings in which:

[0028] [Fig-1] [Fig.1] is an overview of a pressure sensor according to the invention, comprising a deformable wall, a magnetic circuit and a device for estimating a pressure value, according to a first arrangement of the magnetic circuit;

[0029] [Fig.2] [Fig.2] includes a first three-dimensional view, denoted A, analogous to that of [Fig.1] and according to the first arrangement of the magnetic circuit, and a second cross-sectional view according to the cutting plane BB, noted B;

[0030] [Fig.3] [Fig.3] is a view analogous to that of [Fig.1] according to a second arrangement of the magnetic circuit;

[0031] [Fig.4] the [Fig.4] and a view similar to that of the [Fig.1] according to a third arrangement of the magnetic circuit;

[0032] [Fig.5] [Fig.5] is a graph representing pairs of measured pressure and associated impedance values, and a law defining a relationship between the measured impedance and the estimated pressure.

[0033] In [Fig.1], an aircraft 5 includes a pressure sensor 10. The aircraft 5 is, for example, an airplane, a helicopter, or even a remotely piloted drone.

[0034] The pressure sensor 10 comprises a housing 12 including a deformable wall 14 on which a magnetic circuit 16 formed by a conductive ink is deposited. The pressure sensor 10 further comprises an electronic estimation device 18 connected to the magnetic circuit 16.

[0035] The housing 12 is, for example, in the shape of a cylindrical capsule. It comprises several walls 24, such as one or more side walls and substantially horizontal upper and lower walls, defining an internal volume 26 subject to pressure variation. One of the walls 24 is a deformable wall 14, which conforms to the pressure variation within the internal volume 26. The deformable wall 14 is, for example, the upper horizontal wall, and the lower horizontal wall typically forms a base.

[0036] According to a first example of the housing arrangement 12, the deformable wall 14 preferably comprises a cylindrical hole 27 tapped along an axis perpendicular to a surface of the deformable wall 14 on which the conductive ink is deposited. A structural screw 28 is engaged in the cylindrical hole 27 and has a thread corresponding to the tapping of the cylindrical hole 27. The structural screw 28 holds the magnetic circuit 16 in place on the deformable surface 14.

[0037] According to a second example of the arrangement of the housing 12, the cylindrical orifice passes completely through the housing along an axis perpendicular to the surface of the deformable wall 14 on which the conductive ink is deposited.

[0038] The walls 24 are preferably made of stainless steel. More generally, the housing 12 is preferably made of stainless steel. This material allows the deformation of the deformable wall 14 to be measurable from a pressure variation on the order of ten pascals. This material also provides the walls 24 with resistance up to a pressure of up to 2400 Pa.

[0039] The deformable wall 14 is also represented on [Fig.2], in the form of a three-dimensional view A; as well as a schematic sectional view B, corresponding to a cross-section of the wall 14 along the section plane BB.

[0040] As can be seen in cross-sectional view B of [Fig.2], the deformable wall 14 preferably comprises an alternation of hollows 30 projecting towards the internal volume 26 and of bumps 32 projecting outwards from the case 12, in the form of undulations from its centre relative to a horizontal median plane parallel to a surface of the deformable wall 14 on which the conductive ink is deposited.

[0041] The magnetic circuit 16 is formed by a conductive ink arranged on the deformable wall 14. The conductive ink is preferably made of a conductive material, such as graphene or a ferromagnetic element.

[0042] The magnetic circuit 16 deforms as a consequence of the deformation of the wall 14 according to the pressure variation, which modifies its impedance. A greater length of the magnetic circuit 16 increases the impedance variation for the same deformation of the wall 14. Advantageously, a greater impedance variation improves the accuracy of the sensor 10 for a given pressure variation.

[0043] According to a first embodiment of the sensor 10, the measured pressure is that of the air contained in the internal volume 26 of the housing 12. The magnetic circuit 16 is then advantageously deposited at the bumps 32 on the external surface of the deformable wall 14 of the housing 12. In this way, the magnetic circuit 16 undergoes a greater deformation and therefore a greater variation in impedance for the same deformation of the wall 14.

[0044] According to a second embodiment of the sensor 10, the pressure measured is that of the environment external to the housing 12. The magnetic circuit 16 is then advantageously deposited at the level of the hollows 30 on the internal surface of the deformable wall 14 of the housing 12. In this way, the magnetic circuit 16 undergoes a greater deformation and therefore a greater variation in impedance for the same deformation of the wall 14.

[0045] Fig. 1 represents a first arrangement, according to which the magnetic circuit 16 is in the form of a spiral 33, defining a turn 34 at each convolution. A first terminal portion 35A of the magnetic circuit 16 is located at the periphery of the wall 14, while the cylindrical orifice 27 and the structural screw 28 provide a passage within which a second terminal portion 35B of the magnetic circuit 16 is disposed. Preferably, the spiral 33 comprises a minimum of ten turns 34.

[0046] Figure 3 represents a second arrangement in which the magnetic circuit 16 is advantageously in the form of a boustrophedon spiral 33 36 according to the following description. A first terminal portion 35A of the magnetic circuit 16 is located at the end of the deformable wall 14, extending from the loop 34 furthest from the center of the deformable wall 14. A second terminal portion 35B of the magnetic circuit 16 is in the form of a segment extending radially from the center of the deformable wall 14 towards the end of the deformable wall 14. The intermediate portion of the magnetic circuit 16 is arranged in a back-and-forth configuration on the Deformable wall 14: The loop 34 furthest from the center of the deformable wall 14 forms a convolution interrupted by the radial arrangement of the second terminal portion 35B, and is then connected to the next loop 34 towards the center of the deformable wall 14 by a radial portion of the magnetic circuit 16. The next loop 34 forms a convolution in the opposite direction to the previous one. This arrangement is repeated by all the loops 34 up to the center of the deformable wall 14 so as to present a magnetic circuit 16 of greater length than in the first arrangement, for a deformable wall 14 of the same area.

[0047] Figure 4 represents a third arrangement in which the magnetic circuit 16 is in the form of a boustrophedon spiral 36 with the same configuration as the second arrangement. In this third arrangement, each turn 34 is further crenellated and thus comprises slots 38. These slots 38 are advantageously arranged radially on either side of a peripheral direction of extension of the corresponding turn 34. According to this third arrangement, the magnetic circuit 16 is even longer than in the second arrangement, for a deformable wall 14 of the same area.

[0048] In other words, a person skilled in the art will understand that for the same deformable wall area 14, and among the first, second and third arrangements described above, the magnetic circuit 16 of greatest length is that according to the third arrangement, and the magnetic circuit 16 of shortest length is that according to the first arrangement.

[0049] The electronic estimation device 18 comprises a measurement module 40 and a calculation module 42 as shown in [Fig.1].

[0050] The electronic estimation device 18 typically includes an information processing unit formed for example of a memory and a processor associated with the memory, not shown.

[0051] In the example of [Fig. 1], the measurement module 40 and the calculation module 42 are each implemented as a software program, or a software component, executable by the processor. The memory of the estimation device 18 is then capable of storing a measurement program and a calculation program. The processor is then capable of executing either the measurement program or the calculation program.

[0052] In an alternative not shown, the measurement module 40 and the calculation module 42 are each implemented as a programmable logic component, such as an FPGA (Field Programmable Gate Array), or as a dedicated integrated circuit, such as an ASIC (Application-Specific Integrated Circuit).

[0053] When the estimation device 18 is implemented in the form of one or more software programs, i.e., in the form of a computer program, it is also capable of being recorded on a computer-readable medium, not shown. The medium A computer-readable medium is, for example, a medium capable of storing electronic instructions and being connected to a computer system bus. Examples of readable media include optical discs, magneto-optical discs, ROMs, RAM, any type of non-volatile memory (e.g., EPROM, EEPROM, FLASH, NVRAM), magnetic cards, and optical cards. A computer program containing software instructions is then stored on this readable medium.

[0054] The measuring module 40 is configured to obtain at least one impedance value of the magnetic circuit 16.

[0055] When the measuring module 40 is implemented in the form of software, the measuring module 40 is configured to acquire at least one impedance value measured by a sensor, not shown, connected directly to the magnetic circuit 16. The measuring module 40 is then connected to said sensor.

[0056] Alternatively, the measuring module 40 includes said sensor, and is then configured to directly measure at least one impedance value of the magnetic circuit 16.

[0057] The measured impedance is for example an inductance of the magnetic circuit 16, and the sensor is then typically an inductance meter.

[0058] Alternatively, the measured impedance is a capacitance of the magnetic circuit 16, and the sensor is then typically a capacitance meter.

[0059] The calculation module 42 is connected to the measurement module 40.

[0060] The calculation module 42 is configured to calculate the estimated pressure value at starting from a predetermined law defining a relationship between impedance and pressure.

[0061] The law is preferably obtained by interpolation from a predefined set of pairs of measured values ​​of pressure and associated impedance.

[0062] According to an example of a protocol for obtaining such a law, a plurality of pressure values ​​are generated within the internal volume 26. For each pressure value, a measurement of the impedance of the magnetic circuit 16 is obtained by the measuring module 40. A plurality of pairs of pressure values ​​44 within the internal volume 26 and the associated impedance of the magnetic circuit 16 are thus determined. As shown in [Fig. 5], the pairs of values ​​44 are arranged on a graph associating the impedance of the magnetic circuit 16 obtained by the measuring module 36 with the pressure generated within the internal volume 26. A straight line 46 is obtained by linear interpolation, representing the law defining the relationship between the impedance of the magnetic circuit 16 and the pressure within the internal volume 26. In the example of [Fig.[5], impedance values ​​are inductance values, denoted IND and expressed in microhenries or pH, pressure being denoted P and expressed in hectopascals or hPa.

[0063] Alternatively, the predetermined law is non-linear. For example, the determined law is obtained from a polynomial interpolation of the pairs of values ​​obtained.

[0064] It is thus understood that the pressure sensor 10 according to the invention is compact, resistant, and less sensitive to mechanical vibrations than the pressure sensor of the prior art.

Claims

Demands

1. Pressure sensor (10) comprising: - a deformable wall (14) under the effect of pressure; - a magnetic circuit (16) deposited on the deformable wall (14), the circuit (16) having an impedance varying according to the deformation of the wall (14); - an electronic estimation device (18) comprising a measurement module (40) of the impedance of the magnetic circuit and a calculation module (42) of an estimated pressure value from the measured impedance; characterized in that the magnetic circuit (16) is formed by a conductive ink deposited on the deformable wall (14).

2. Pressure sensor (10) according to claim 1, characterized in that it comprises a housing (12) having several walls (24) defining an internal volume (26) subject to a pressure variation, the deformable wall (14) being formed by one of the walls (24) of the housing (12).

3. Pressure sensor (10) according to any one of the preceding claims, characterized in that the deformable wall (14) has, from its center, an alternation of hollows (30) and bumps (32) in the form of undulations with respect to a horizontal median plane, parallel to a surface of the deformable wall (14) on which the conductive ink is deposited.

4. Pressure sensor (10) according to claims 2 and 3, characterized in that: - when the measured pressure is an internal pressure in the housing (12), the conductive ink is deposited on the bumps (32); and - when the measured pressure is an external pressure in the housing (12), the conductive ink is deposited on the hollows (30).

5. Pressure sensor according to any one of the preceding claims, characterized in that the magnetic circuit is in the form of a spiral (33), and each convolution of the magnetic circuit (16) defines a turn (34); the magnetic circuit (16) preferably comprising at least 10 turns (34).

6. Pressure sensor (10) according to claim 5, characterized in that the spiral (33) formed by the magnetic circuit (16) is in the shape of a boustrophedon (36).

7. Pressure sensor (10) according to claim 5 or 6, characterized in that the spiral (33) is crenellated.

8. Pressure sensor (10) according to any one of the preceding claims, characterized in that the wall (14) is deformable from a pressure variation greater than ten pascals; the wall (14) preferably being resistant to a pressure of up to 2400 pascals.

9. Pressure sensor (10) according to any one of the preceding claims, characterized in that the calculation module (42) is configured to calculate the estimated pressure value from a predetermined law defining a relationship between impedance and pressure; said law preferably being obtained from a predefined set of pairs of a measured pressure value and an associated impedance value.

10. Aircraft (5) characterized in that it comprises a pressure sensor (10) according to any one of the preceding claims.

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