A measuring device that autonomously and wirelessly detects liquid media in the environment.

Abstract

The present invention relates to a measuring device 1 for detecting at least one property of a liquid medium 2 in an environment 3, comprising at least two electrodes 6 arranged within the environment 3 and spaced apart from each other, and an electrode 6 assembled to measure the capacitance of the intermediate space between the electrodes. The measuring device 1 further comprises, namely, at least one surface acoustic wave (SAW) sensor 7,11,13, a non-conductive support layer 15, at least one antenna 16, and at least one interrogator. The electrodes 6 are attached to the non-conductive support layer 15, and two electrodes 6 are electrically connected to the surface acoustic wave sensors 7,11,13. The antenna 16 is located inside the environment 3 and is electrically connected to an interrogator 19 located outside the environment 3 by an electrical connection part 17 through a through-opening 18 in the environment housing 4. A wireless request signal 30 from the interrogator 19 can be transmitted by the antenna 16 to the surface acoustic wave sensors 7,11,13. Surface acoustic wave sensors 7, 11, and 13 can be activated by a request signal 30, and a wireless response signal 38 can be received by the antenna 16 and transmitted to the interrogator 19. The response signal 38 can be evaluated by the interrogator 19 or a separate evaluation device, the capacitance between the electrodes 6 is measured, and at least one characteristic of the medium in the environment 3 is determined from that capacitance.

Description

Technical Field

[0001] The present invention relates to a measuring device for detecting at least one property of a liquid medium in an environment according to the preamble part of claim 1, comprising at least two electrodes arranged in the environment and spaced apart from each other, the electrodes being assembled for measuring the capacitance / electrical capacitance of the intermediate space between them.

Background Art

[0002] In known measuring devices, a filling level sensor that measures the capacitance inside a tank is electrically connected to electrodes in order to measure properties of a liquid medium, such as the filling level in the tank, and is also connected to an external measuring amplifier outside the tank by means of at least two coaxial connections passing through openings in the wall of the tank. Eventually, for example, for 5 sensors each having 2 electrodes, 10 coaxial connections, and thus 10 openings or 1 correspondingly large opening are required in the wall of the tank. Most of these coaxial connections are realized by means of airtight feed-throughs through the tank housing / tank capsule using special plugs. On the one hand, these plugs must be suitable for low electrical signals for measuring capacitance, and on the other hand, they must be able to be used in a demanding temperature environment with high mechanical loads such as vibrations and mechanical shocks. A further important aspect is the airtightness at the through openings / feed-through openings for the coaxial connections. An important basic requirement for the safe operation of a tank for a liquid medium, for example a tank having liquid cryogenic fuel for a launcher, is the airtightness of these through openings. For the passage of electrical signals, the structural housing of the tank is perforated, and as a result, a reliable seal of the electrical through openings is required. When using liquid hydrogen as fuel for a launcher, the realization of this seal poses a challenge due to the small molecular size of hydrogen.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Therefore, the object of the present invention is to provide a measuring device that enables reliable measurement of the state or characteristics of a medium in an environment and sufficient sealing of the environmental enclosure that defines the environment. [Means for solving the problem]

[0004] This objective is achieved by a measuring device having the features of patent claim 1.

[0005] The present invention relates to a measuring device for a liquid medium in an environment, comprising at least two electrodes placed in the environment and spaced apart from each other, assembled to measure the capacitance of the intermediate space between the electrodes. In this case, the measuring device further comprises at least one surface acoustic wave (SAW) sensor, a non-conductive support layer, at least one antenna, and at least one interrogator, the electrodes being mounted on the non-conductive support layer. The two electrodes are electrically connected to the surface acoustic wave sensor, and the antenna is electrically connected to the interrogator located outside the environment, which is placed inside the environment and through an electrical connection via a through-opening in the environment housing. A wireless request signal / inquiry signal from the interrogator can be transmitted to the surface acoustic wave sensor by the antenna. The surface acoustic wave sensor is activated by the request signal, and a wireless response signal can be received by the antenna and transmitted to the interrogator. The response signal can be evaluated by the interrogator to measure the capacitance between the electrodes and to determine / calculate at least one characteristic of the liquid medium inside the environment from that capacitance.

[0006] The environment may be, for example, a pipe segment of a liquid distribution system or a tank such as a fuel tank. Another term for the environment is balance space. Characteristics to be detected may include, for example, the fill level, the distribution of the liquid medium in the environment, the portion of the liquid medium in the environment, the type of liquid medium, the temperature of the liquid medium, the flow direction, and the flow velocity. Detection is performed directly, i.e., wirelessly and preferably autonomously.

[0007] This measuring device uses at least one surface acoustic wave (SAW) sensor. A surface acoustic wave (SAW) sensor is a passive radio sensor that converts the electromagnetic waves of a request signal into surface acoustic waves using an interdigital converter (IDT) = piezoelectric substrate antenna, which are then manipulated by the physical variables to be measured. The manipulated surface acoustic waves are converted back into an electromagnetic response signal by the IDT and emitted. This response signal can be received and measured, and the capacitance value of a liquid medium can be determined from the changed response signal.

[0008] In principle, two principles are used to manipulate surface acoustic waves using measurement variables:

[0009] Surface acoustic waves are, for example, resonances generated in a sensor by a request signal, and can be a type of surface acoustic wave (SAW) sensor that utilizes the excitation of a resonance having a corresponding resonance frequency. As soon as the request signal is switched off, the surface acoustic wave sensor transmits a decayed response signal having a specific resonance frequency. This resonance frequency depends, among other things, on the measured variable, in this case capacitance.

[0010] Surface sensors can be, for example, delay-line type surface acoustic wave (SAW) sensors that utilize changes in the velocity or path of surface acoustic waves. For this purpose, a reflector is used in the SAW sensor that reflects the elastic surface after receiving the excitation signal and sends it back to the IDT. The timing of the reflection depends, in particular, on the physical position of the reflector, which is changed by the measured variable, in this case the capacitance of the liquid medium.

[0011] By determining the time difference between the excitation signal and the response signal (caused by reflection), it is possible to determine the measurement variable.

[0012] The activation / excitation and interpretation of response signals resulting from the request signal are performed by a so-called interrogator. This interrogator transmits an electromagnetic request signal having a specific frequency spectrum and power spectrum, and receives a low-power response signal from at least one surface acoustic wave sensor via an antenna.

[0013] Therefore, the measurement variable can generally be measured up to a distance of approximately 10m between the sensor and the interrogator, for example, without any cable connection.

[0014] In this case, at least one surface acoustic wave sensor operates completely passively (a purely mechanical structure without electronic components) and does not require a local energy supply such as a battery. This makes it possible to use at least one surface acoustic wave sensor in demanding environments such as low temperatures, high acceleration, and environments with ionizing radiation. Therefore, this measuring device is particularly suitable for measuring liquid media such as liquid fuel in the tanks of launch vehicles.

[0015] The liquid medium can be a cryogenic liquid fuel for launch vehicles such as LOX and LH2. This liquid medium affects the capacitance inside the tank during filling due to changes in the dielectric constant of the liquid medium, and thus the tank's filling level can be determined, for example, by measuring the capacitance of at least one surface acoustic wave sensor.

[0016] The external interrogator may include a measuring amplifier and / or measuring converter that converts a small response signal into a sufficiently large voltage signal based on capacitance values. This voltage signal may then be obtained from the launch vehicle controller and used, for example, to calculate the launch vehicle's filling level.

[0017] The non-conductive support layer can be made from any desired electrical insulating material, such as Kapton or a glass fiber layer.

[0018] Electrical connections passing through the environmental enclosure may be equipped with seals suitable for sealing liquid media inside the environment, such as cryogenic fuel for a launch vehicle, under low temperature and high pressure conditions.

[0019] Therefore, a wireless request signal is transmitted via an antenna by the interrogator to the surface sensor, which is then excited and activated, and the antenna sends a wireless response signal back to the interrogator. The response signal is evaluated by the interrogator to measure the capacitance between electrodes and then derive, for example, the internal filling level of the environment.

[0020] The determination of at least one characteristic of the liquid medium in that environment, such as the filling level inside the tank, based on the measured capacitance between each electrode, is performed by a questioning machine or by a separate evaluation device.

[0021] The evaluation device may be implemented in the form of an electronic circuit or a programmable computer suitable for evaluating the response signal of a surface acoustic wave sensor, from which the capacitance is determined, and thus at least one characteristic of the liquid medium in that environment is determined.

[0022] The electrodes may be mounted inside the tank or on the internal structure of the tank, for example, on a baffle plate to avoid vortices inside the tank.

[0023] One advantage of the measuring device is that it can use surface acoustic wave sensors to measure the filling level in demanding environments such as low temperatures, high acceleration, high mechanical loads, and ionizing radiation, and thus this measuring device is particularly suitable for measuring at least one characteristic or state of a liquid medium in the launch vehicle environment, for example, to detect the filling level of a launch vehicle's tank.

[0024] A further advantage of the measuring device is that the antenna is arranged inside the tank and excites at least one surface acoustic wave sensor by means of a request signal, so that only a single through-opening having an electrical connection between the antenna and the interrogator is required. Thus, the surface acoustic wave sensor or these surface acoustic wave sensors do not require their own electrical connection to a connection leading outside the tank housing, but are excited wirelessly. Thereby, the tightness of the tank is improved, in particular, in the case of liquid media such as liquid hydrogen due to the small molecule size.

[0025] A further advantage of the measuring device is that the cables do not need to electrically connect these surface acoustic wave sensors outside the tank housing, and thus no further through-opening is required, so that the position, number and size of the surface acoustic wave sensors can be variably selected. For example, in order to determine the filling level in different regions of the internal volume of the tank or the distribution of the liquid medium in the environment, for example, a large number of surface acoustic wave sensors enable a correspondingly high measurement resolution of the capacitance tomography inside the tank.

[0026] A further advantage of the measuring device is that it is possible to integrate passive surface acoustic wave sensors already used inside the environment during production, for example by means of functional printing, which ultimately improves the quality of the operating mode and the production period of the surface acoustic wave sensors and electrical connections inside the tank.

[0027] Advantageously, a plurality of surface acoustic wave sensors each having a set of electrodes can be attached to a non-conductive support layer inside the tank. Each of the surface acoustic wave sensors can be excited by a wireless request signal via the antenna, and each of the surface acoustic wave sensors transmits a wireless response signal back to the antenna and further to the interrogator. For example, in order to calculate the filling level inside the tank, the response signals of each of the surface acoustic wave sensors can be evaluated by the interrogator or by a separate evaluation device.

[0028] Ultimately, a set of electrodes inside the environment is connected to each of the surface acoustic wave sensors, thereby enabling capacitance measurement in different regions of the internal volume of the environment, and thus enabling fill level measurement inside the environment, for example, in different regions. In the case of cryogenic liquid media such as liquid fuels LOX and LH2 for launch vehicles, which are partially liquid and partially gaseous, measurement of the fill level in multiple regions of the internal volume of the environment is particularly advantageous. For example, the topography of the fill level can be determined from individual measurements in order to better report on the fill level of the launch vehicle.

[0029] Advantageously, a set of electrodes for each of the surface acoustic wave sensors can be arranged at a specific defined fill height of the tank, and the response signal of each surface acoustic wave sensor can be evaluated by a interrogator or a separate evaluation device in order to determine at least one characteristic such as the fill level at the defined fill height of the tank.

[0030] Ultimately, the capacitance is measured at specific defined heights in multiple regions of the internal volume of the tank, whereby the fill height can be determined for various regions at this defined height.

[0031] Advantageously, at least two sets of electrodes for each of the surface acoustic wave sensors can be arranged at at least two different defined fill heights of the tank in order to determine the fill level at multiple defined fill heights.

[0032] Ultimately, it becomes possible to measure the capacitance at different fill heights of the tank, and thereby the fill level can be determined at different heights of the tank.

[0033] Advantageously, multiple sets of electrodes for each surface acoustic wave sensor can be arranged at each of at least two different defined fill heights of the tank.

[0034] Ultimately, capacitance measurement becomes possible at different filling heights in different regions of the tank's internal volume, thereby enabling a more accurate determination of the topography of the filling level within the tank's internal volume.

[0035] A further subject of the present invention is a measurement method for measuring at least one characteristic of a liquid medium in an environment, such as the fill level in a tank, using the aforementioned measuring device, wherein a wireless request signal is transmitted from a questioner to a surface acoustic wave sensor via an antenna. The surface acoustic wave sensor is activated by the request signal, receives a wireless response signal, and transmits it to the questioner via an antenna. The response signal is evaluated by the questioner or a separate evaluation device to determine the characteristics of the liquid medium inside the environment.

[0036] One advantage of this measurement method is that surface acoustic wave sensors are wirelessly excited by a request signal from a questioning machine, and a response signal is wirelessly transmitted back to the questioning machine by an antenna, thereby allowing any desired number of surface acoustic wave sensors to be placed at any desired location inside the tank to determine the filling level in the internal volume of the tank for various regions.

[0037] Advantageously, multiple sets of electrodes for each surface acoustic wave sensor may be positioned at a specific, predetermined filling height of the tank, and the response signals of each surface acoustic wave sensor are evaluated by a questioner or a separate evaluation device to determine the filling level at the predetermined filling height of the tank.

[0038] Ultimately, capacitance and, therefore, the filling level for various regions of the tank's internal volume can be measured at a predetermined filling height.

[0039] Advantageously, at least two sets of electrodes for surface acoustic wave sensors may be positioned at at least two different defined filling heights of the tank, and the response signals of each surface acoustic wave sensor are evaluated by a questioner or a separate evaluation device to determine the filling level at a plurality of defined filling heights.

[0040] Ultimately, the capacitance and, therefore, the filling level can be determined by a number of predetermined filling heights.

[0041] Advantageously, the response signal is influenced by the capacitance value between the electrodes of at least one surface acoustic wave sensor, so that during environment filling, the capacitance value between the electrodes changes due to the dielectric constant of the liquid medium which is different from that of the gas present in the environment, and therefore the change in the response signal is evaluated by a questioner or a separate evaluation device to detect at least one characteristic such as the filling level.

[0042] The gases in the environment may be air, fuel gases / propellant gases such as hydrogen, or gaseous mixtures of air and fuel gas. The capacitance of the gases in the environment can also be measured using a measuring device. Therefore, when filling a tank, the capacitance between each set of electrodes changes due to the different dielectric constants of the liquid medium, thus allowing for the precise determination of the filling level.

[0043] A further subject of the present invention is a method for manufacturing the aforementioned measuring device. At least one surface acoustic wave sensor and at least two electrodes are attached, for example by lamination, to a non-conductive support layer made of Kapton, in the form of at least one pre-assembled and integrated sensor band.

[0044] One example of this manufacturing method is the use of a pre-assembled sensor band including a surface acoustic wave sensor, two electrodes, and the electrical connection between them, which reduces manufacturing time and improves the complexity of the internal assembly of the tank.

[0045] The application of a non-conductive support layer can be similarly carried out by laminating it, for example, onto a film made of Kapton.

[0046] Lamination, on the one hand, refers to a thermal bonding method that is connected by materials without the use of preliminary materials. On the other hand, it refers to the bonding of thin, often film-like layers to a support material with adhesives, and further to the bonding of at least two film layers of thermoplastic material by reaching a glass transition temperature and corresponding pressure.

[0047] Advantageously, to determine the fill level inside the tank for various fill heights, multiple integrated fill level sensor bands may be mounted on the inner wall or inside of the tank at different fill heights.

[0048] For example, by laminating and attaching integrated fill level sensor bands to different fill heights, manufacturing time can be shortened and potential assembly errors can be avoided.

[0049] Advantageously, at least one surface acoustic wave sensor, a support layer, and at least two electrodes can be automatically and directly printed onto the inner wall of the tank by a printing method such as functional printing.

[0050] In functional printing (functional integration through printing technology), typical electrical components such as sensors are automatically mounted on a surface. In this case, a conductive paste is applied to the surface using digital and mask-based printing techniques. Different sensors, in this case surface acoustic wave sensors, can be realized by printing various geometric shapes. Functional printing allows for the printing of not only two-dimensional surfaces, but also three-dimensional curved surfaces using multi-axis equipment (e.g., industrial robots). Thus, functional printing allows piezoelectric elements to be printed from piezoelectric substrates, and conductive elements and electrodes of surface acoustic wave sensors to be printed from conductive paste.

[0051] Therefore, the use of functional printing automates the manufacturing of surface acoustic wave sensors and the mounting of support layers, thus shortening manufacturing time and simplifying complexity, as manual mounting and thus potential errors are avoided.

[0052] Advantageously, a non-conductive support layer can be attached by plasma surface treatment, lamination of a Kapton film, or lamination of a glass fiber layer.

[0053] The surface is thoroughly cleaned by plasma surface treatment, improving adhesion for subsequent lamination.

[0054] Ultimately, the manufacturing of the non-conductive support layer is automated, and therefore, the manufacturing time is shortened.

[0055] Advantageously, a piezoelectric layer for a surface acoustic wave sensor is attached to a non-conductive support layer and polarized by a dispenser using multi-axis equipment such as an industrial robot. Next, the reflector and electrodes of the interdigital converter and / or surface acoustic wave sensor are attached to the support layer using a conductive paste.

[0056] Industrial robots equipped with dispensers or dispensing devices enable automated and controlled distribution of materials to workpieces, and the distribution process can be controlled in a reliable, exceptionally accurate, and repeatable manner.

[0057] The use of such industrial robots enables the fully automated manufacturing and integration of surface acoustic wave sensors inside tanks.

[0058] Further subject matter of the present invention is an environment, preferably for a spacecraft or launch vehicle, such as a fuel tank, having the aforementioned measuring device, a measuring device for applying the aforementioned measuring method, and / or a measuring device manufactured according to the aforementioned manufacturing method.

[0059] Since the capacitance inside the launch vehicle environment is guaranteed even under high temperature fluctuations, high mechanical loads, and high acceleration, one advantage of this environment, which has the aforementioned measuring device manufactured according to the aforementioned manufacturing method, is that it is particularly suitable for launch vehicles.

[0060] Preferred embodiments of the present invention will be described below with reference to a very simplified schematic drawing. [Brief explanation of the drawing]

[0061] [Figure 1] This figure shows a schematic representation of a measuring device having multiple surface acoustic wave sensors. [Figure 2] This figure shows a schematic diagram illustrating the operating modes of a surface acoustic wave sensor with electrostatic coupling. [Figure 3] This figure shows a schematic representation of pre-integrated sensor bands. [Figure 4] This figure shows a schematic representation of a sensor band attached inside the environment. [Figure 5] This figure shows a schematic diagram illustrating a manufacturing method using industrial robots. [Modes for carrying out the invention]

[0062] In exemplary embodiments, the measuring device according to the present invention is described as a measuring device for directly (wirelessly and autonomously) measuring the filling level of a liquid medium in a tank. However, it should be clearly noted that this measuring device according to the present invention is not limited to detecting the filling level of a liquid medium in a tank. The description as a filling level measuring device is entirely illustrative. The description of the tank is also entirely illustrative. In general, the measuring device according to the present invention can directly detect at least one characteristic / at least one state of a liquid medium in an environment or balance space. In addition to quantitative characteristics such as filling level (amount) and distribution, qualitative characteristics of the liquid medium in the environment such as the type of medium, temperature, flow direction and flow velocity can also be detected. Exemplary environments, in addition to fuel tanks, are generally tanks and pipelines of, for example, liquid distribution systems.

[0063] Figure 1 shows a schematic diagram of a measuring device 1 for a fuel, particularly a liquid medium such as liquid hydrogen, inside the environment of a launch vehicle / launch pad tank 3. Multiple spaced electrodes 6 are mounted on the inner wall or inside 5 of the environment enclosure, in this case the tank enclosure 4, and these electrodes are configured to measure the capacitance in the intermediate space between the electrodes 6 inside the tank 3 (inside the environment). The measuring device further has a first surface acoustic wave sensor 7, which is connected to a first electrode 9 and a second electrode 10 by multiple electrical connections 8, so that the capacitance in the region between the first electrode 9 and the second electrode 10 is measured by the first surface acoustic wave sensor 7. A second surface acoustic wave sensor 11 is electrically connected to the first electrode 9 and the third electrode 12, so that the capacitance in the region between the first electrode 9 and the third electrode 12 is measured. A third surface acoustic wave sensor 13 is electrically connected to the first electrode 9 and the fourth electrode 14 by an electrical connection 8, thereby measuring the capacitance in a third region between the first electrode 9 and the fourth electrode 14. Similarly, additional surface acoustic wave sensors may be connected to the remaining electrodes 6 to cover further areas of the inner volume of the tank 3. Electrodes 6, 9, 10, 12 and 14 are attached to the inner wall 5 of the tank housing 4 by a non-conductive support layer 15. An antenna 16 is located inside the tank 3 and is electrically connected to an interrogator (caller, reader) 19 outside the tank 3 by an electrical connection 17 through a through-opening 18 that passes through the tank housing 4 of the tank 3. The through-opening 18 is sealed in this case using a seal 20 so that the liquid medium 2 cannot be forced outwards. A wireless request signal from the interrogator 19 is transmitted via the antenna 16 inside the tank, activating (exciting) the corresponding surface acoustic wave sensors 7, 11, and 13 via their respective electrode pairs 6, 9, 10, 12, and 14. These surface acoustic wave sensors transmit response signals back to the antenna 16 and further back to the interrogator 19. The response signals are evaluated to measure the capacitance between the electrodes and thereby determine the characteristics or state of the liquid medium, such as the filling level in the tank 3 (from the capacitance).

[0064] Figure 2 is a schematic diagram illustrating the operating modes of the surface acoustic wave sensors 7, 11, and 13 in Figure 1. The interrogator 19 sends a wireless request signal 30 via its internal antenna 16, as indicated by the arrows. This request signal is transmitted to an interdigital converter (IDT) 32 via multiple antennas 31. The electromagnetic waves of the request signal 30 are converted into surface acoustic waves 34 of the request signal 30 using a piezoelectric substrate 33. The surface acoustic waves 34 of the request signal 30 are again converted into electromagnetic waves by a reflector 35 and transmitted to both electrodes 9 and 10, respectively. A response signal 36 is correspondingly generated depending on the capacitance between the two electrodes 9 and 10, as indicated by the arrows. This response signal is again converted into surface acoustic waves 37 of the response signal 36 by the reflector 35 using the piezoelectric substrate 33. The surface acoustic wave 37 of the response signal 36 is converted into an electromagnetic wave 38 of the response signal 36 by an interdigital converter (IDT) 32 and transmitted by an antenna 31 to the antenna 16 of the interrogator 19. The electromagnetic wave 38 of the response signal 36 is then evaluated (interpreted) by the interrogator 19 to determine the capacitance between electrodes 9 and 10, from which the characteristics or state of the liquid medium, such as the filling level in tank 3, are determined. Similarly, the second surface acoustic wave sensor 11 and the third surface acoustic wave sensor 13 are also activated and excited using the request signal 30, and their response signals are read.

[0065] Figure 3 shows a schematic diagram of a pre-assembled, integrated sensor band 40, including a first electrode 41 and a second electrode 42. Electrodes 41 and 42 are electrically connected to the first surface acoustic wave sensor 7 in Figures 1 and 2 by conductive tracks 8. The two electrodes 41, 42, the first surface acoustic wave sensor 7, and the conductive tracks 8 are mounted to a non-conductive support layer 15, which is made of, for example, a film made from Kapton or a glass fiber layer. The pre-assembled, integrated sensor band 40 can be mounted to the inner wall 5 of the tank 3 in Figure 1 in a simple manner.

[0066] Figure 4 shows a schematic representation of the sensor band 40 of Figure 3, including a first surface acoustic wave sensor 7, a first electrode 41, and a second electrode 42, mounted on a non-conductive support layer 15 attached to the inner wall 5 of the tank housing 4. An internal antenna 16 is connected to an interrogator (not shown) through a through-opening 18 of the tank housing 4, which is sealed by a seal 20.

[0067] Figure 5 shows a schematic diagram illustrating the manufacturing method of the measuring device 1 of Figure 1 using an industrial robot 50. The measuring electrodes 9 and 10 and at least one surface acoustic wave sensor 7 are fully and automatically attached to the inner wall 5 of the tank housing 4 of the tank 3 using a printing method (functional printing). First, a non-conductive support layer 15 is attached using plasma surface treatment and layered on a Kapton film or a glass fiber layer. Next, the piezoelectric layer for the surface acoustic wave sensor 7 of Figure 2 is attached to this non-conductive support layer 15 by a dispenser 51 of the industrial robot 50 and polarized. Next, the interdigital converter (IDT) 32 and / or reflector 35 and electrodes 9 and 10 of Figure 2 are attached to the support layer using conductive paste. As a result, this manufacturing method enables the fully automatic integration of the wireless surface acoustic wave sensor 7 and associated electrodes 9 and 10 to the inner wall 5 of the tank housing 4.

[0068] The present invention relates to a measuring device (1) for a liquid medium (2) in an environment (3), comprising at least two electrodes (6) arranged in the environment (3) and spaced apart from each other, the measuring device (1) further comprising at least one surface acoustic wave (SAW) sensor (7,11,13), a non-conductive support layer (15), at least one antenna (16), and at least one interrogator, wherein the electrodes (6) are mounted on the non-conductive support layer (15), the two electrodes (6) are electrically connected to the surface acoustic wave sensor (7,11,13), and the antenna (16) is located inside the environment (3) and has a through-opening through the environment housing (4) The present invention relates to a measuring device (1) characterized in that it is electrically connected to an interrogator (19) located outside the environment (3) by an electrical connection part (17) passing through (18), a wireless request signal (30) from the interrogator (19) can be transmitted to surface acoustic wave sensors (7,11,13) by an antenna (16), the surface acoustic wave sensors (7,11,13) can be activated by the request signal (30), a wireless response signal (38) can be received by the antenna (16) and transmitted to the interrogator (19), and the response signal (38) can be evaluated by the interrogator (19) or a separate evaluation device in order to measure the capacitance between electrodes (6) and determine at least one characteristic of a medium in the environment (3) from that capacitance. [Explanation of symbols]

[0069] 1. Measuring device 2. Liquid media 3. Environment / Balance Space / For example, a tank 4 Tank enclosure 5 Interior wall / inside 6 Multiple electrodes 7. First surface acoustic wave sensor 8. Electrical connection 9 1st electrode 10 Second electrode 11. Second surface acoustic wave sensor 12 Third electrode 13. Third surface acoustic wave sensor 14 4th electrode 15 Non-conductive support layer 16 Antennas 17 Electrical connection 18 Through-opening 19 Questioning machine 20 stickers 30 Wireless request signals 31 Antenna 32 Interdigital Converter (IDT) 33 Piezoelectric Substrate 34. Surface Acoustic Waves 35 Reflector 36 Response signal 37 Surface Acoustic Waves 38 Electromagnetic Waves 40 sensor bands 41 1st electrode 42 2nd electrode 50 Industrial Robots 51 Dispensers

Claims

1. A measuring device (1) for detecting at least one characteristic of a liquid medium (2) in an environment (3), In a measuring device (1) comprising at least two electrodes (6) arranged in the environment (3) and positioned apart from each other, the measuring device (1) includes an electrode (6) assembled to measure the capacitance of the intermediate space between the electrodes, The measuring device (1) further includes at least one surface acoustic wave (SAW) sensor (7, 11, 13), a non-conductive support layer (15), at least one antenna (16), and at least one interrogator. The electrode (6) is attached to the non-conductive support layer (15), The two electrodes (6) are electrically connected to the surface acoustic wave sensors (7, 11, 13), The antenna (16) is located inside the environment (3) and is electrically connected to the interrogator (19) located outside the environment (3) by an electrical connection part (17) that passes through a through-opening (18) that goes through the environment housing (4). The wireless request signal (30) from the interrogator (19) can be transmitted to the surface acoustic wave sensors (7, 11, 13) by the antenna (16). The surface acoustic wave sensors (7, 11, 13) can be activated by the request signal (30), the wireless response signal (38) can be received by the antenna (16), and can be transmitted to the interrogator (19), The measuring device (1) is characterized in that the response signal (38) can be evaluated by the interrogator (19) or a separate evaluation device in order to measure the capacitance between the electrodes (6) and thereby determine at least one characteristic of the medium in the environment (3).

2. Multiple surface acoustic wave sensors (7, 11, 13), each having one set of electrodes (6), are attached to the non-conductive support layer (15) inside the environmental housing. Each of the surface acoustic wave sensors (7, 11, 13) can be activated by the antenna (16) in response to the wireless request signal (30), and each of the surface acoustic wave sensors (7, 11, 13) transmits a wireless response signal (38) to the antenna (16) and then back to the interrogator (19). The measuring apparatus (1) according to claim 1, characterized in that, in order to determine the characteristics of the medium in the environment (3), the response signals (38) of each of the surface acoustic wave sensors (7, 11, 13) can be evaluated by the interrogator (19).

3. A set of electrodes (6) for each of the surface acoustic wave sensors (7, 11, 13) is placed at a specific defined filling height in the environment (3). The measuring device (1) according to claim 2, characterized in that, in order to determine the filling level at the defined filling height in the environment (3), the response signals (38) of each of the surface acoustic wave sensors (7, 11, 13) can be evaluated by the interrogator (19) or the separate evaluation device.

4. The measuring device (1) according to claim 2, characterized in that, in order to determine the filling level at a plurality of predetermined filling heights, at least two sets of electrodes (6) for each of the surface acoustic wave sensors (7, 11, 13) are positioned at at least two different predetermined filling heights in the environment (3).

5. The measuring device (1) according to claim 4, characterized in that multiple sets of electrodes (6) for each of the surface acoustic wave sensors (7, 11, 13) are arranged in each of the at least two different defined filling heights of the environment (3).

6. A method for measuring at least one property of a liquid medium in an environment (3) using a measuring device (1) according to any one of claims 1 to 5, The wireless request signal (30) is transmitted by the antenna (16) from the interrogator (19) to the surface acoustic wave sensors (7, 11, 13). The surface acoustic wave sensors (7, 11, 13) are activated by the request signal (30), the wireless response signal (38) is received and transmitted to the interrogator (19) by the antenna (16), A measurement method characterized in that the response signal (38) is evaluated by the interrogator (19) or the separate evaluation device in order to determine at least one characteristic of the medium in the environment (3).

7. Multiple sets of electrodes (6) for each of the surface acoustic wave sensors (7, 11, 13) are arranged at a specific defined filling height in the environment (3). The measurement method according to claim 6, characterized in that, in order to determine the filling level at the defined filling height in the environment (3), the response signals (38) of each of the surface acoustic wave sensors (7, 11, 13) are evaluated by the interrogator (19) or the separate evaluation device.

8. At least two sets of electrodes (6) for the surface acoustic wave sensors (7, 11, 13) are arranged at at least two different defined filling heights in the environment (3), The measurement method according to claim 6, characterized in that, in order to determine the filling level at multiple predetermined filling heights, the response signals (38) of each of the surface acoustic wave sensors (7, 11, 13) are evaluated by the interrogator (19) or the separate evaluation device.

9. The measurement method according to any one of claims 6 to 8, characterized in that the response signal (38) is influenced by the capacitance value between the electrodes (6) of the at least one surface acoustic wave sensor, so that during the filling of the environment (3), the capacitance value between the electrodes (6) changes due to the dielectric constant of the liquid medium (2) which is different from that of the gas located in the environment (3), and therefore, in order to detect the filling level, the change in the response signal (38) is evaluated by the interrogator (19) or the separate evaluation device.

10. A method for manufacturing the measuring device (1) according to any one of claims 1 to 5, A manufacturing method characterized in that at least one surface acoustic wave sensor (7) and at least two electrodes (41, 42) are attached to the non-conductive support layer (15), made of, for example, Kapton, in the form of at least one pre-assembled and integrated sensor band (40), for example by lamination.

11. The manufacturing method according to claim 10, characterized in that, in order to determine the filling level in the environment (3) for various filling heights, a plurality of integrated filling level sensor bands (40) are attached to the inside of the environment housing at different filling heights.

12. The manufacturing method according to any one of claims 1 to 5, characterized in that the at least one surface acoustic wave sensor (7), the support layer (15), and the at least two electrodes (9, 10) are automatically and directly printed on the inside of the environmental housing by a printing method such as functional printing.

13. The manufacturing method according to claim 12, characterized in that the non-conductive support layer (15) is attached by surface treatment with plasma, lamination of a film made of Kapton, or lamination of a glass fiber layer.

14. A multi-axis device such as an industrial robot (50) uses a dispenser (51) to attach the piezoelectric layer (33) for the surface acoustic wave sensor (7) onto the non-conductive support layer (15), and polarize it. Next, the manufacturing method according to claim 12 or 13, characterized in that the reflector (35) and electrodes (9, 10) of the interdigital converter (IDT) (32) and / or the surface acoustic wave sensor (7) are attached to the support layer (15) using conductive paste.

15. Preferably, an environment (3) for a spacecraft or launch vehicle having a measuring device (1) according to any one of claims 1 to 5, a measuring device (1) for applying a measuring method according to any one of claims 6 to 9, and / or a measuring device (1) manufactured using a manufacturing method according to any one of claims 10 to 14.

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