Pressure sensor for a fluid circuit or a sealed enclosure of a motor vehicle

Abstract

The present application relates to a pressure sensor for a fluid circuit or a sealed enclosure of a motor vehicle. A pressure sensor (10) for a fluid circuit, in particular a fluid circuit of a motor vehicle, the sensor comprising: a main body (12) comprising a fluid inlet (14), a fluid outlet (16) and an internal chamber (18) for connecting the inlet to the fluid outlet to make a fluid flow in the main body; an elastically deformable membrane (20) located in the chamber, the membrane comprising a first face (20a) for being in contact with the fluid flowing in the main body. The sensor further comprises: an RLC type resonant circuit (22) located in the chamber and associated with a readout circuit (23) located outside the chamber (18).

Description

Technical Field

[0001] The present invention relates in particular to pressure sensors for fluid circuits or sealed housings, especially fluid circuits or sealed housings of motor vehicles. Background Technology

[0002] The prior art includes, in particular, the following documents: US-A1-2006 / 144155, US-B1-7,146,861 and US-A1-2014 / 309577.

[0003] Vehicles, especially automobiles, involve multiple fluid circuits whose pressure must be measured and controlled in real time to check the vehicle's proper operation. This is the case, for example, with a vehicle's fuel system.

[0004] Vehicles, particularly electric or hybrid vehicles, may further include a battery pack comprising a sealed housing in which battery cells are housed. The battery pack may be equipped with pressure sensors to detect pressure rises within the housing, particularly those caused by gas release from a faulty cell.

[0005] Various pressure sensor technologies exist. For example, some pressure sensors include strain gauges located on a membrane in contact with a fluid. As the fluid pressure changes, the membrane deforms, and the change in the resistivity of the strain gauge can be correlated with the fluid pressure. This measurement principle is widely used, but it requires wires to read the strain gauge's changing characteristics.

[0006] Other sensors include piezoelectric materials. However, such sensors also require two wires to measure the voltage generated by pressure on the piezoelectric material.

[0007] The other sensors use MEMS (Micro-Electro-Mechanical Systems) technology, and therefore use semiconductor materials.

[0008] This invention provides a wireless pressure sensor technology, particularly suitable for measurements in hazardous or isolated environments such as fuel systems or sealed enclosures, such as battery packs or the like in motor vehicles. Summary of the Invention

[0009] This invention relates to a pressure sensor for a fluid circuit or a sealed housing, the sensor comprising:

[0010] - An elastically deformable membrane comprising two opposing surfaces, the first of which is for contact with a fluid.

[0011] - An RLC-type resonant circuit, comprising a capacitor and a first coil, the capacitor being located on one of the two surfaces of the diaphragm, the capacitance of the capacitor varying with the magnitude of elastic deformation of the diaphragm, the first coil being connected to the capacitor, and the resonant circuit being configured to have a resonant frequency varying according to the capacitance of the capacitor and the elastic deformation of the diaphragm.

[0012] - A readout circuit, biased from the membrane and including a second coil arranged opposite the first coil, and configured to detect the resonant frequency of the resonant circuit and accordingly transmit a readout signal.

[0013] The capacitor is characterized in that it includes two electrodes, which are respectively connected to the terminals of the first coil, and both electrodes are located on the surface of the membrane, such that both electrodes deform with the elastic deformation of the membrane, and the first coil is located on or above the surface of the membrane.

[0014] Therefore, it can be understood that the cooperation between the resonant circuit and the readout circuit is achieved without wires. In other words, not connecting the resonant circuit via wires is advantageous and facilitates the manufacture and maintenance of the sensor. The readout circuit can be connected to other electronic devices, particularly to the vehicle's onboard computer, via wires.

[0015] It is also understandable that the capacitor occupies little space because its two electrodes are located on the membrane, rather than occupying a large amount of space above the membrane. The two electrodes follow the deformation of the membrane, thus being advantageously flexible, and can be, for example, in the form of a thin film or layer. Arranging the first coil on or above the membrane also optimizes the space requirements of the sensor.

[0016] The pressure sensor according to this application may include one or more of the features described below, which may be independent of each other or in combination with each other:

[0017] --The shape of the membrane is usually flat, such as a disc;

[0018] - The capacitor includes a stacked structure on the surface of the membrane, the stacked structure including two stretchable conductive layers separated by a dielectric layer, the conductive layers forming electrodes and respectively connected to the terminals of the first coil;

[0019] - The capacitor includes two flat and stretchable electrodes located on the second surface of the membrane, the electrodes being interleaved and connected to the terminals of the first coil, respectively;

[0020] --The outer diameter of the first and second coils is less than or equal to the outer diameter of the membrane or the maximum lateral dimension;

[0021] The sensor includes a body, and the membrane is installed in the body;

[0022] - The body includes an outer annular fastening flange or a peripheral fastening flange, the flange extending around the membrane and including an orifice for the passage of a fastening element;

[0023] - The main body includes a one-piece housing, the housing including a central portion and two extensions, the central portion defining the chamber, and the two extensions forming the inlet and outlet respectively;

[0024] --The central portion of the housing has a generally cylindrical shape, and the extensions are radially opposite to the axis of the central portion;

[0025] - The main body also includes a cover that is attached and secured to the central portion and defines a space for accommodating the resonant circuit with the membrane;

[0026] - The outer periphery of the membrane is clamped by the fastening flange, or clamped between the cover and the central portion, so that the membrane provides a seal;

[0027] --The membrane includes annular or peripherally thickened portions at its outer periphery;

[0028] - The second coil is located on the cover, or the second coil is carried by a cover located above the cover;

[0029] - The first coil and the second coil share a common winding axis;

[0030] --The winding axis coincides with the axis of the central portion;

[0031] - The entire resonant circuit is located on the surface of the membrane, the capacitor of the resonant circuit is located on the central portion of the membrane, and the first coil is located on the annular or peripheral portion of the membrane, the annular or peripheral portion extending around the central portion;

[0032] --The resonant circuit is located on the surface of the membrane exposed to the fluid or on the surface opposite to the surface of the membrane exposed to the fluid;

[0033] - The central portion of the membrane has a constant thickness E1, and the annular or peripheral portion has a constant thickness E2 greater than the thickness E1, and for example, the constant thickness E2 is at least three times the thickness E1 and at most ten times the thickness E1.

[0034] - The membrane also includes an annular or peripheral beaded edge at its outer periphery, the annular or peripheral beaded edge being connected to the annular or peripheral portion of the membrane by an annular or peripheral web of material with a thickness of E3, the thickness of E3 being between the thickness of E1 and the thickness of E2.

[0035] --The web is sandwiched between two coaxial cylindrical rims of the main body;

[0036] - The second coil is connected to an electronic control device, which includes a first module and a second module, the first module being configured to adjust the impedance of the RLC circuit and the second module being configured to analyze the vector frequency;

[0037] --The first coil extends around the axis of the central portion.

[0038] The present invention also relates to a fluid circuit, particularly a fluid circuit for motor vehicles, the fluid circuit comprising at least one sensor as described above.

[0039] The present invention also relates to a sealed housing, such as a battery pack, particularly a battery pack for a motor vehicle, the sealed housing including at least one sensor as described above.

[0040] The present invention also relates to vehicles, particularly automobiles, which include at least one sensor, circuit, or sealed housing as described above. Attached Figure Description

[0041] Other features and advantages of the invention will become apparent from the following detailed description, and this description is facilitated by referring to the accompanying drawings, in which:

[0042] Figure 1 This is a schematic diagram of the pressure sensor according to the present invention;

[0043] Figure 2 This is a schematic diagram illustrating an example of an embodiment of the interleaved electrodes of a variable capacitor for an RLC circuit of a pressure sensor according to the present invention;

[0044] Figure 3 The resonant circuit and readout circuit of the pressure sensor according to the present invention are shown;

[0045] Figure 4 This is a perspective view of an embodiment of the pressure sensor according to the present invention;

[0046] Figure 5 for Figure 4 A schematic axial cross-sectional view of a pressure sensor;

[0047] Figure 6 This is a partial perspective cross-sectional schematic diagram of an alternative embodiment of the pressure sensor according to the present invention;

[0048] Figure 7 This is a partial perspective cross-sectional schematic diagram of an alternative embodiment of the pressure sensor according to the present invention;

[0049] Figure 8 This is a partial perspective cross-sectional schematic diagram of an alternative embodiment of the pressure sensor according to the present invention;

[0050] Figure 9 This is an exploded perspective view of another embodiment of the pressure sensor according to the present invention;

[0051] Figure 10 for Figure 9 A perspective view of the membrane of the sensor;

[0052] Figure 11 For along Figure 9 A cross-sectional view of line IX-IX;

[0053] Figure 12 This is a partial perspective view of a battery pack-type sealed housing equipped with a sensor according to another variation of the present invention.

[0054] Figure 13 for Figure 12 A perspective view of the sensor;

[0055] Figure 14 for Figure 12 Another perspective view of the sensor; and

[0056] Figure 15 for Figure 12 A schematic axial cross-sectional view of the sensor. Detailed Implementation

[0057] This invention relates to pressure sensors equipped with fluid circuits or sealed housings, particularly those for motor vehicles. The fluid circuit is, for example, a fuel system. The sealed housing is, for example, a battery pack type, i.e., a casing housing a battery pack. However, these applications of the sensors according to the invention are not limited to these.

[0058] according to Figures 1 to 11 In the first embodiment shown, the pressure sensor 10 is used to equip a fluid circuit. The sensor 10 includes a body 12 (e.g., made of a plastic material) that includes a fluid inlet 14, a fluid outlet 16, and an internal chamber 18 for connecting the inlet to the fluid outlet, so that fluid flows from the inlet 14 to the outlet 16 within the body 12 (see arrow F).

[0059] The sensor 10 also includes an elastically deformable membrane 20 having a first surface 20a designed to contact fluid flowing through the body 12.

[0060] In this application, "membrane" refers to a substantially flat and elastically deformable element. The membrane is made of an elastically deformable material (e.g., an elastomer). As will be described in more detail below, the properties of the membrane, particularly the magnitude of its elastic deformation, can be used to measure the pressure of the fluid flowing within the body.

[0061] Therefore, the membrane 20 includes a surface 20a (the lower surface in this example) that is in contact with the fluid, and also includes a surface 20b (the upper surface in this example).

[0062] Membrane 20 separates, for example, a chamber 18 located below membrane 20 from a space 19 located above membrane 20.

[0063] Preferably, chamber 18 and space 19 are sealed relative to each other, and this seal is preferably ensured by membrane 20, as described below.

[0064] During deformation, when the fluid is under negative pressure, the membrane 20 moves from a flat state toward the interior of the chamber 18 to a curved state, and when the fluid is under overpressure, the membrane 20 moves from a flat state toward the interior of the space 19 to a curved state.

[0065] The pressure sensor 10 also includes two circuits: a resonant circuit 22 and a readout circuit 23.

[0066] The resonant circuit 22 is housed in space 19, and the readout circuit 23 is located outside space 19.

[0067] The resonant circuit 22 is of type RLC, that is, it can be considered as including a series resistor 22a (letter R-see). Figure 3 A circuit consisting of an inductor or coil 22b (letter L) and a capacitor 22C or a capacitor (letter C).

[0068] In fact, the resonant circuit 22 includes a capacitor 22c mounted on the terminals of the coil 22b, and the resistance of the circuit 22 is formed by the resistance of the coil and the capacitor itself.

[0069] The capacitor 22c of the resonant circuit 22 is located directly on the diaphragm 20, particularly on surface 20b of the diaphragm. The capacitor 22c is configured such that its capacitance varies according to the magnitude of elastic deformation of the diaphragm 20. Depending on the configuration of the capacitor 22c, a greater magnitude of deformation results in a larger capacitance, or conversely, a lower capacitance.

[0070] According to the present invention, the capacitor 22c includes two electrodes, which are respectively connected to the corresponding terminals of the first coil 22b, and are both located on the surface 20b of the membrane 20, such that they can deform in accordance with the elastic deformation of the membrane.

[0071] Advantageously, the electrode is flexible and therefore deformable. The electrode may be in the form of a thin film or a layer.

[0072] According to the first configuration, capacitor 22c includes... Figure 1 The visible stacked structure is located on surface 20b and includes two stretchable conductive electrodes or layers 24 and 28 separated by dielectric layer 26. Conductive layers 24 and 28 form electrodes and are respectively connected to the terminals of coil 22b.

[0073] according to Figure 2 In another configuration shown, capacitor 22c includes two flat and stretchable electrodes 30, 32 located on face 20b, the electrodes 30, 32 being interleaved or crossed, and these electrodes being respectively connected to the terminals of the first coil 22b.

[0074] In each of these configurations, preferably, capacitor 22c is protected by a passivation layer deposited on at least a portion of capacitor 22c and face 20b.

[0075] Preferably, the coil 22b has an annular or cylindrical shape and extends around axis A, which is preferably located at the center of membrane 20. In other words, the coil 22b and membrane 20 are coaxial.

[0076] Furthermore, preferably, the outer diameter of the coil 22b is smaller than the outer diameter or the maximum lateral dimension of the membrane 20.

[0077] like Figure 1 As shown, coil 22b can be located on top of membrane 20, but it can also be located on membrane 20, particularly on the surface 20b of membrane.

[0078] The readout circuit 23 includes another coil 23b, preferably arranged opposite to the first coil 22b, and configured to detect the resonant frequency of the resonant circuit 22 and output a readout signal accordingly.

[0079] Preferably, coil 23b has an annular or cylindrical shape and extends around axis A. Therefore, preferably, the axis is located at the center of coil 22b and membrane 20.

[0080] Furthermore, preferably, the outer diameter of coil 23b is smaller than the outer diameter or maximum lateral dimension of membrane 20, and preferably, the outer diameter of coil 23b is the same as the outer diameter of coil 22b.

[0081] Coil 23b is located above coil 22b, and its terminals are connected to an electronic control device comprising a first module 34 and a second module 36. The first module 34 is configured to adjust the impedance of the readout antenna (i.e., coil 23b), and the second module 36 is configured to follow changes in the resonant frequency of circuit 22, such as... Figure 1 and Figure 3 As shown.

[0082] Module 34 enables impedance matching of the readout antenna so that all transmitted energy is emitted (i.e., reflections are minimized). Module 34 can consist of capacitors and inductors connected in series or parallel, as needed.

[0083] Module 36 is a frequency vector analyzer. It performs a frequency scan within a given range, which allows it to follow the evolution of the circuit's resonant frequency.

[0084] The operation of the pressure sensor 10 according to the present invention is described below. Under the influence of deformation of the diaphragm 20, which is associated with the pressure of the fluid, the capacitance of the capacitor 22c changes, thereby causing a change in the resonant frequency of the resonant circuit 22. The shift in the resonant frequency is proportional to the pressure applied by the fluid.

[0085] In practice, it may be necessary to calibrate the pressure sensor 10 to determine the transformation function of pressure change relative to frequency offset.

[0086] Figures 4 to 11 A more specific embodiment of the pressure sensor 10 according to the present invention is shown.

[0087] exist Figure 4 and Figure 5 In the embodiment shown, the main body 12 of the sensor 10 includes an integral housing 38, which includes a central portion 38a defining a chamber 18, and two extensions 38b and 38c forming an inlet 14 and an outlet 16, respectively.

[0088] The central portion 38a of the housing 38 is generally cylindrical with an axis A, and the extensions 38b and 38c are radially opposite each other with respect to the axis A.

[0089] The main body 12 also includes a cover 40, which is attached and fixed to the central portion 38a and defines a space 19 therein where the resonant circuit 22 is located.

[0090] Membrane 20 separates chamber 18 from space 19, and the outer periphery of the membrane is clamped between cover 40 and central portion 38a. Thus, membrane 20 provides a seal between chamber 18 and space 19. The outer periphery of membrane 20 may include an annular overthickness 20c, which is designed to be axially compressed to ensure that the seal reaches a sufficient pressure exceeding the maximum pressure that fluid can reach through chamber 18.

[0091] Preferably, the membrane 20 has a generally flat, for example, disc-shaped shape, and its outer diameter or lateral dimension can be between 10 mm and 50 mm, preferably between 20 mm and 40 mm. Alternatively, the membrane may have other shapes.

[0092] The minimum thickness of the membrane is between 1 mm and 3 mm, and the maximum thickness at the outer periphery of the membrane is between 3 mm and 8 mm, preferably between 4 mm and 7 mm.

[0093] Figures 6 to 8 An alternative embodiment of the pressure sensor 10 is shown.

[0094] exist Figure 6 In this circuit, the coil 23b of the readout circuit is supported by a cover 42, which is positioned above and at a distance from the cover 40. The coil 23b is housed in a recess of the cover and is thus protected by it.

[0095] The coil 22b of the resonant circuit 22 is positioned above the diaphragm 20 and is supported by the cover 40 of the body 12 of the sensor 10. A wire 44 connects the terminals of the coil 22b to a capacitor 22c located on the surface 20b of the diaphragm 20.

[0096] In the following text, the term "ring" may refer to a generally disc-shaped element or portion of the membrane. If the membrane is not precisely of such a shape, "ring" should be interpreted, for example, as "periphery".

[0097] The annular overthick portion 20c of the membrane 20 is sandwiched between the cover 40 and the housing 38 of the body 12. The housing 38 and the cover 40 include cylindrical edges 38d and 40d that extend about axis A and face each other, and the membrane 20 is sandwiched between these edges.

[0098] Figure 7 Alternative embodiments and Figure 5 The difference in the embodiment is that the cover 42 directly mates with the cover 40 and can be fixed to the cover 40. Therefore, there is no distance or gap between the cover 42 and the cover 40.

[0099] Figure 8 The alternative embodiments shown are similar to Figure 5 and 6 The difference in the illustrated embodiment is that it does not include a cover. The coil 23b is carried by the cover 40, and in the illustrated example, a cylindrical extension 40a surrounding the cover 40 extends along axis A.

[0100] Now for reference Figures 9 to 11 This illustrates another alternative embodiment of the pressure sensor 10 according to the present invention.

[0101] The essential difference between this alternative embodiment and the previous embodiment lies in the membrane 20 and the resonant circuit 22.

[0102] The entire resonant circuit 22 is located on surface 20b of the diaphragm 20. The capacitor 22c of the resonant circuit 22 is located on the central portion 46 of the diaphragm 20, and the coil 22b is located on the annular portion 48 of the diaphragm 20 extending around the central portion 46.

[0103] The central portion 46 of the membrane 20 has a constant thickness E1, and the annular portion 48 has a constant thickness E2 greater than E1, and for example, the constant thickness E2 is at least three times or even five times E1. Preferably, E2 is at most ten times E1.

[0104] The membrane 20 also includes an annular beaded edge 50 at its outer periphery, which is connected to the annular portion 48 of the membrane 20 by an annular web 52 of material with a thickness of E3. E3 is between E1 and E2.

[0105] like Figure 9 As shown, the web plate 52 is respectively sandwiched between the two cylindrical edges 38d and 40d of the shell 38 and the cover 40 (edge ​​40d of the cover 40 is not shown).

[0106] Figures 12 to 15 Another embodiment of the sensor 110 according to the invention is shown, which is used herein for mounting a sealed housing of the battery pack type.

[0107] The casing or battery pack is in Figure 12 As shown in the middle section, the casing or battery pack includes a housing 112, in which battery cells 114 are housed. For clarity, only two battery cells are shown.

[0108] Battery cell 114 is enclosed in a sealed housing 112. If at least one of the cells 114 fails, it will generate heat and produce gas inside the housing 112. Due to the sealed nature of the housing, this gas will increase the internal pressure of the housing, and a pressure sensor 110 is designed to detect this pressure rise, thereby detecting the cell failure.

[0109] The housing 112 includes a wall 112a, which includes a through-hole 116 at which a sensor 110 is mounted. In the example shown, the hole 116 and the sensor 110 are located substantially in the middle of the wall 112a. The sensor 110 is externally mounted to the hole 116 to seal the hole.

[0110] Sensor 110 is similar to the sensor described above, and it also includes a diaphragm 20 equipped with a resonant circuit 22. However, unlike sensor 10, the resonant circuit 22 of sensor 110 is located on the surface 20a that will be exposed to the fluid (gas), and is therefore located on the inner side of the housing.

[0111] The sensor 110 is fixed to the wall 112a by a suitable fastening device.

[0112] Here, sensor 110 includes a body 118, which includes an outer annular fastening flange 120. The flange 120 extends around membrane 20 and includes an aperture 122 aligned with an aperture in wall 112a for passage of screw-nut type fastening element 124.

[0113] The body 118 and the membrane 20, with the surface 20b opposite to the surface 20a, define a space for accommodating the readout circuit 23.

[0114] The body 118 includes a plug-in electrical connector 126 that enables the readout circuit 23 to be electrically connected to electronic control devices (particularly modules 34, 36).

[0115] Preferably, the material of the membrane 20 is an elastomer, and for example, hydrogenated nitrile butadiene rubber (HNBR).

[0116] Membrane 20 may have one or more of the following properties:

[0117] - Tensile strength is between 10MPa and 40MPa

[0118] - The International Rubber Hardness Index (IRHD) ranges from 50 to 100.

[0119] The elongation at break is between 100% and 600%, preferably between 200% and 500%.

Claims

1. A pressure sensor (10, 110) for a fluid circuit or hermetically sealed housing, the sensor comprising: - An elastically deformable membrane (20), the membrane comprising two opposing surfaces (20a, 20b), one of the opposing surfaces being in contact with a fluid. - An RLC-type resonant circuit (22) comprising a capacitor (22c) and a first coil (22b), the capacitor being located on one of the surfaces (20a, 20b) of the membrane, the capacitance of the capacitor varying with the amplitude of elastic deformation of the membrane, the first coil being connected to the capacitor, and the resonant circuit being configured to have a resonant frequency varying according to the capacitance of the capacitor and the elastic deformation of the membrane, and - A readout circuit (23), biased from the membrane and including a second coil (23b), the second coil being arranged opposite to the first coil (22b), and the second coil being configured to detect the resonant frequency of the resonant circuit and accordingly transmit a readout signal. The resonant circuit (22) is located on the surface of the membrane (20), the capacitor (22c) of the resonant circuit is located on the central portion (46) of the membrane, the capacitor (22c) includes two electrodes, the two electrodes are respectively connected to the terminals of the first coil (22b), and the two electrodes are located on the surface of the membrane (20) such that the two electrodes deform with the elastic deformation of the membrane (20), and the first coil (22b) is located on or above the surface of the membrane (20) and on the annular or peripheral portion (48) of the membrane, the annular or peripheral portion extending around the central portion of the membrane.

2. The sensor (10, 110) according to claim 1, wherein, The capacitor (22c) includes a stacked structure on the surface of the membrane, the stacked structure including two stretchable conductive layers (24, 28) separated by a dielectric layer (26), the conductive layers (24, 28) forming the electrodes.

3. The sensor (10, 110) according to claim 1, wherein, The electrodes (30, 32) are flat and stretchable on the surface of the membrane and are interleaved with each other.

4. The sensor (10, 110) according to any one of the preceding claims, wherein, The sensor also includes a body (12, 118) in which the membrane (20) is mounted.

5. The sensor (110) according to claim 4, wherein, The body (118) includes an outer annular fastening flange or a peripheral fastening flange (120) that extends around the membrane (20) and includes an aperture (122) for the passage of a fastening element (124).

6. The sensor (10) according to claim 4, wherein, The body (12) includes a fluid inlet (14), a fluid outlet (16) and an internal chamber (18), the internal chamber being used to connect the inlet to the fluid outlet so that fluid can flow in the body, and the readout circuit (23) being located outside the chamber (18) and separated from the chamber by the membrane (20).

7. The sensor (10) according to claim 6, wherein, The main body (12) includes an integral housing (38) including a central portion (38a) and two extensions (38b, 38c), the central portion (38a) defining the chamber (18), and the two extensions (38b, 38c) forming the inlet (14) and outlet (16), respectively.

8. The sensor (10) according to claim 7, wherein, The main body (12) also includes a cover (40) which is attached and fixed to the central portion (38a) of the housing and defines a space (19) with the membrane for accommodating the resonant circuit (22).

9. The sensor (10) according to claim 8, wherein, The second coil (23b) is located in the body (118) and on the cover (40), or the second coil is carried by a cover (42) located above the cover.

10. The sensor (10, 110) according to claim 5, wherein, The outer periphery of the membrane (20) is clamped by the fastening flange (120), thereby providing a seal.

11. The sensor (10, 110) according to any one of claims 1 to 3, wherein, The first coil (22b) and the second coil (23b) share a common winding axis.

12. The sensor (10, 110) according to any one of claims 1 to 3, wherein, The central portion (46) of the membrane (20) has a constant thickness E1, and the annular or peripheral portion (48) has a constant thickness E2 that is greater than the thickness E1.

13. The sensor (10, 110) according to any one of claims 1 to 3, wherein, The membrane (20) also includes an annular or peripheral beaded edge (50) at its outer periphery, which is connected to the annular or peripheral portion (48) of the membrane (20) by an annular or peripheral web (52) of material with a thickness of E3, the thickness of E3 being between thickness E1 and thickness E2.

14. The sensor (10, 110) according to any one of claims 1 to 3, wherein, The second coil (23b) is connected to an electronic control device, which includes a first module (34) and a second module (36), the first module being configured to adjust the impedance of the RLC circuit and the second module being configured to analyze the vector frequency.

15. The sensor according to claim 1, wherein, The fluid circuit or sealing housing is the fluid circuit or sealing housing of a motor vehicle.

16. The sensor (10, 110) according to claim 8 or 9, wherein, The outer periphery of the membrane (20) is clamped between the cap (40) and the central portion (38a) of the housing, thereby providing a seal.

17. The sensor according to claim 12, wherein, The constant thickness E2 is at least three times the thickness E1 and at most ten times the thickness E1.

18. A fluid circuit comprising at least one sensor (10) according to any one of the preceding claims.

19. The fluid circuit according to claim 18, wherein, The fluid circuit is used in motor vehicles.

20. A sealed housing comprising at least one sensor (110) according to any one of claims 1 to 17.

21. The sealed housing according to claim 20, wherein, The sealed outer casing is a battery pack.

22. The sealed housing according to claim 21, wherein, The battery pack is used in motor vehicles.

23. A vehicle comprising at least one sensor (10) according to any one of claims 1 to 17, a circuit according to claim 18, or a sealed housing according to claim 20.

24. The vehicle according to claim 23, wherein, The vehicle in question is a car.

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