Electronic unit for a level measurement probe

Abstract

An electronic unit (10, 30) for a level measuring probe (15, 34) for measuring a level of a medium, the electronic unit comprising at least one first excitation electronic unit (11) arranged to emit a first excitation signal and at least one second excitation electronic unit (12) arranged to emit a second excitation signal, wherein the first excitation signal is different from the second excitation signal, and wherein the electronic unit (10, 30) is arranged to emit the first excitation signal and the second excitation signal simultaneously to the level measuring probe (15, 34).

Description

[0001] Cross-references to related applications

[0002] This application claims priority to German patent application 10 2020 200879.5, filed on January 24, 2020, and German patent application 10 2020 200866.3, filed on January 24, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to an electronic unit for a level measuring probe, a level measuring probe having such an electronic unit, and the use of the electronic unit in a level measuring probe. Background Technology

[0004] For example, the filling level or limiting level can be monitored using a conductivity measurement method. For this purpose, conductivity is measured in the filling medium. Alternatively, the filling level or limiting level can be monitored using a capacitance measurement method. Here, the level is determined from the capacitance formed by the measuring electrode and, for example, the container wall or a reference electrode.

[0005] The application scope of these two measurement methods may differ. For example, for conductivity-based measurement methods, a certain minimum conductivity of the filling medium is crucial. Conversely, if the electrodes of the level measurement probe are designed as bare electrodes, very high conductivity may cause problems in capacitive level measurements. Adhesion on the probe will also have different effects.

[0006] It has now been found that there is a need to provide an improved electronic unit for level measurement probes. Summary of the Invention

[0007] Therefore, one object of the present invention is to provide an improved electronic unit for a level measurement probe.

[0008] The present invention provides an electronic unit for a level measuring probe used to measure the level of a medium. The electronic unit includes: at least one first excitation electronic unit configured to transmit a first excitation signal; and at least one second excitation electronic unit configured to transmit a second excitation signal; wherein the first excitation signal and the second excitation signal are different; and wherein the electronic unit is configured to simultaneously transmit the first excitation signal and the second excitation signal to the level measuring probe.

[0009] In other words, the present invention proposes to provide an electronic unit that can simultaneously perform two measurement methods. Here, the excitation signal can be transmitted to the level measuring probe as a single excitation signal or as a combined excitation signal.

[0010] Preferably, the at least one first excitation electronic unit is configured to emit a first excitation signal for conductive level measurement, and preferably, the at least one second excitation electronic unit is configured to emit a second excitation signal for capacitive level measurement. In this case, it should be noted that the invention is not limited to a combination of conductive and capacitive measurements, although such a combination is particularly preferred. Instead, the same or different measurement principles can be used in the invention.

[0011] Advantageously, the first excitation signal and the second excitation signal have different frequencies. Furthermore, preferably, the first excitation electronic unit is configured to emit a square wave signal and / or a sine wave signal as the first excitation signal, preferably for conductive level measurement, wherein, preferably, the square wave signal and / or the sine wave signal is emitted at a frequency of 5 kHz. Furthermore, preferably, the second excitation electronic unit is configured to emit a triangular wave signal and / or a sine wave signal and / or a square wave signal as the second excitation signal, preferably for capacitive level measurement, wherein, preferably, the triangular wave signal and / or the sine wave signal and / or the square wave signal is emitted at a frequency of 355 kHz.

[0012] Preferably, the first excitation electronic unit and / or the second excitation electronic unit includes at least one direct digital synthesis (DDS) unit to provide the first excitation signal and / or the second excitation signal.

[0013] Advantageously, the first excitation electronics unit and the second excitation electronics unit are configured to transmit the first excitation signal and the second excitation signal in such a way that the first excitation signal and the second excitation signal have the same arithmetic mean. Therefore, for example, offset differences can be avoided within the range of the excitation electronics, thus allowing the evaluation electronics to advantageously not have to take this into account.

[0014] Preferably, the electronic unit further includes at least one first evaluation electronic unit for evaluating conductive level measurements and / or at least one second evaluation electronic unit for evaluating capacitive level measurements, wherein the combined output signal of the level measurement probe exists as the input signal of the first evaluation electronic unit and / or the second evaluation electronic unit.

[0015] In this configuration, preferably, the first evaluation electronic unit is equipped with a first filter unit configured to filter out a first output signal for conductive level measurement from the combined output signal; and / or wherein the second evaluation electronic unit is equipped with a second filter unit configured to filter out a second output signal for capacitive level measurement from the combined output signal. In this configuration, it is also preferable that the first filter unit is a digital filter unit comprising at least one bandpass filter unit having a center frequency corresponding to the first excitation signal; and / or wherein the second filter unit is a digital filter unit comprising at least one bandpass filter unit having a center frequency corresponding to the second excitation signal. Therefore, in this evaluation configuration, a switching device for switching back and forth between conductive and capacitive signals is not required in the receiving branch. However, the evaluation is not limited to this configuration and can also be performed, for example, by a processor unit and / or an analog-designed evaluation electronic unit. Furthermore, alternatively or additionally, units for performing continuous Fourier transform on the analog combined output signal of the level measurement probe and / or for performing discrete Fourier transform on the digital combined output signal may also be provided. Advantageously, the electronic unit includes at least one first analog-to-digital converter (ADC) configured to convert at least one digital excitation signal from the electronic unit into an analog excitation signal that can be transmitted as an analog excitation signal to the level measuring probe. Depending on the structure of the level measuring probe, two independent excitation signals can be transmitted to the level measuring probe, or a single combined excitation signal can be transmitted to the level measuring probe. In this case, it should be noted that the invention is not limited to a specific analog-to-digital structure. Rather, the entire signal operation can be analog or digital. Analog-to-digital combinations can also be used when using a corresponding ADC. Here, such a conversion unit generally converts the signal from analog to digital form and vice versa; therefore, without excluding a particular conversion direction, the terms "analog-to-digital conversion unit" and "digital-to-analog conversion unit" will be used hereinafter.

[0016] Preferably, the electronic unit includes at least one second analog-to-digital converter (ADC) unit configured to convert at least one combined analog output signal of the level measurement probe into a digital combined output signal that can be transmitted as a digital combined output signal to the two evaluation electronic units.

[0017] Preferably, the electronic unit includes a weighting unit configured to weight the measurement results of conductive and capacitive level measurements based on the medium-specific properties of the medium being measured, wherein the medium-specific properties are preferably the conductivity and / or dielectric constant of the medium being measured. Therefore, the measurement results of the electronic unit can be adjusted within a range where measurement methods more suitable for specific media and / or specific environmental conditions are given greater influence on the measurement results. In this case, it is particularly preferred that one or more medium-specific properties are determined from test signals and / or calibration signals. For example, such test signals and / or calibration signals can be periodically emitted and evaluated, allowing the electronic unit to automatically adapt to potentially changing environmental conditions and / or different media. Such test signals can also be provided through periodic measurements. If the evaluation of the test signals and / or calibration signals indicates that one of the two measurement methods cannot provide meaningful measurement results, for example, because the conductivity of the filling medium is too low or too high, making conductive or capacitive measurements meaningless, then one of the two excitation signals can be deactivated, and if necessary, the corresponding component of the electronic unit required for this measurement method can also be deactivated. In this situation, under certain circumstances or after a certain period of time, the deactivated measurement method can be restarted (trialed) to subsequently determine whether the conditions have changed and whether the measurement method can be performed again in a meaningful manner. This saves energy and time because if one of the two measurement methods cannot provide meaningful measurement results, it is unnecessary to evaluate both measurement methods. In this case, the operator can also manually deactivate one of the two measurement methods, so that the electronic unit performs measurements using only one method under these circumstances.

[0018] Furthermore, the present invention relates to a level sensor or level measuring device for measuring level, comprising at least one electronic unit as described above. In the present context, the term "level measuring sensor" should be interpreted broadly, and it includes all devices capable of detecting the filling level and / or limiting level of a medium in a container, pipe, tank, or the like.

[0019] Finally, the present invention relates to the use of the electronic unit described above in a level sensor or level measuring device for measuring level. Attached Figure Description

[0020] The accompanying drawings will be described in detail below.

[0021] Figure 1 A schematic diagram of a preferred embodiment of an electronic unit for a level measurement sensor according to the present invention is shown.

[0022] Figure 2A schematic diagram of another preferred embodiment of the electronic unit according to the present invention is shown. Detailed Implementation

[0023] Figure 1 A schematic diagram of a preferred embodiment of the electronic unit 10 for a level measuring sensor or level measuring device according to the present invention is shown.

[0024] Electronic unit 10 includes a first excitation electronic unit 11 for generating a first excitation signal for conductive level measurement. In a preferred embodiment, the first excitation signal is a digital square wave signal or a digital sine wave signal with a frequency of 5 kHz. Furthermore, the electronic unit also includes a second excitation electronic unit 12 for generating a second excitation signal for capacitive level measurement. In a preferred embodiment, the second excitation signal is a digital triangular wave signal, a sine wave signal, or a square wave signal with a frequency of 355 kHz. For example, the electronic unit can transmit these excitation signals in a manner that gives the first and second excitation signals the same arithmetic mean, wherein this averaging can also be achieved through a corresponding capacitor (e.g., Figure 1 The capacitors 13, 14 or shown Figure 1 The capacitors 20 and 21 shown are used. Particularly preferably, the two excitation signals are transmitted as a combined excitation signal, as this avoids large offset differences.

[0025] For example, excitation electronics units 11 and 12 may include a direct digital synthesis (DDS) unit to provide a digital excitation signal. However, the invention is not limited to digital signal generation. Although excitation electronics units 11 and 12 are designed as separate units in the illustrated embodiment, they can also be combined into a single unit. Figure 1 As shown, current isolation sections in the form of capacitors 13 and 14 can also be placed in the signal path.

[0026] Then, the excitation signals can be simultaneously transmitted to the level measuring probe 15, wherein the excitation signals can be transmitted to the level measuring probe 15 as a combined excitation signal or as a separate excitation signal. Alternatively, the excitation signals can be transmitted to the level measuring probe 15 in digital or analog form.

[0027] Finally, in the preferred embodiment shown, the electronic unit 10 further includes a first evaluation electronic unit 16 for evaluating conductive level measurements and a second evaluation electronic unit 17 for evaluating capacitive level measurements, wherein the combined output signal of the level measuring probe 15 exists as the input signal of the first evaluation electronic unit 16 and the second evaluation electronic unit 17. In principle, the signal from the level measuring probe 15 is emitted by the level measuring probe 15 in analog form. However, the level measuring probe 15 may also have an analog-to-digital conversion unit, and therefore the combined output signal may also be provided in digital form. Figure 1 As shown, the first evaluation electronic unit 16 is equipped with a first filter unit 18, which is configured to filter out a first output signal for conductive level measurement from the combined output signal. The second evaluation electronic unit 17 is equipped with a second filter unit 19, which is configured to filter out a second output signal for capacitive level measurement from the combined output signal.

[0028] For example, the first filter unit 18 can be configured as a digital filter unit including at least one bandpass filter unit whose center frequency corresponds to the first excitation signal. The second filter unit 19 can also be configured as a digital filter unit having at least one bandpass filter unit whose center frequency corresponds to the second excitation signal. However, the evaluation of the output signal of the level measurement sensor 15 is not limited to this configuration and can also be performed, for example, by a processor unit and / or by an analog-designed evaluation electronics unit. Furthermore, alternatively or additionally, units for performing a continuous Fourier transform on the analog combined output signal of the level measurement probe or for performing a discrete Fourier transform on the digital combined output signal can also be provided. The signals from the evaluation electronics units 16, 17 can then be passed to the output unit 22 and / or another processor unit, which, for example, derives the specific level of the container from the signals from the evaluation electronics units 16, 17.

[0029] Furthermore, it should be noted that more than two excitation signals and more than two evaluation electronic units with different filter units may also be provided. Therefore, the present invention is not limited to the two excitation signals and two evaluation electronic units exemplarily given.

[0030] Figure 2A second preferred exemplary embodiment of the electronic unit 30 according to the invention is shown. In this exemplary embodiment, the electronic unit 30 further includes a first digital-to-analog converter 33, which converts the two excitation signals 32 generated in the excitation evaluation electronic unit 31 shown herein into a combined analog excitation signal and transmits it to the level measurement probe 34. For example, the excitation evaluation electronic unit 31 may include a microcontroller with corresponding peripheral devices and software. Here, the excitation evaluation electronic unit 31 may, for example, be as follows: Figure 1 The structure is shown. Furthermore, the electronic unit 30 may, for example, have another electronic unit 35 for performing Fourier transforms, which converts the analog combined output signal of the level measurement probe 34, then inputs the converted signal to, for example, a second analog-to-digital converter 36, and then to the excitation evaluation electronic unit 31 for further evaluation.

[0031] In this context, it should be noted that the invention is not limited to a specific analog-to-digital structure. Instead, the entire signal operation can be either analog or digital. An analog-to-digital combination can also be used when employing a suitable analog-to-digital conversion unit. Figure 2 The embodiment shown is primarily designed in digital form, but it is also possible to filter only the output signal of the level measurement probe or to form the excitation signal only in digital form.

[0032] However, the present invention is not limited to the preferred exemplary embodiments described above, as long as it is covered by the subject matter of the appended claims. Furthermore, it should be noted that the terms "comprising" and "having" do not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. Moreover, the term "unit" should be interpreted broadly; in particular, it should not be construed as meaning that the corresponding unit must be designed as a single, integral component. The individual units may also be positioned differently. Finally, different units may also be combined in a single component. Furthermore, it should be noted that features or steps described with reference to one of the above exemplary embodiments may also be used in conjunction with other features or steps of the other exemplary embodiments described above.

[0033] List of reference numerals

[0034] 10. A first exemplary embodiment of the electronic unit according to the present invention

[0035] 11 First Excitation Electronic Unit

[0036] 12 Second Excitation Electronic Unit

[0037] 13 capacitors

[0038] 14 capacitors

[0039] 15 Level Measurement Probe

[0040] 16 First Evaluation Electronic Unit

[0041] 17 Second Evaluation Electronic Unit

[0042] 18 First Filter Unit

[0043] 19 First Filter Unit

[0044] 20 capacitors

[0045] 21 capacitors

[0046] 22 output units

[0047] 30. A second exemplary embodiment of the electronic unit according to the present invention

[0048] 31 Incentive Evaluation Electronic Unit

[0049] 32 stimulus signals

[0050] 33 Analog-to-Digital Conversion Unit / Digital-to-Analog Conversion Unit

[0051] 34 level measurement probe

[0052] 35-electron unit (Fourier transform)

[0053] 36 analog-to-digital converter units / digital-to-analog converter units

Claims

1. An electronic unit (10, 30) for a level measuring probe (15, 34), the level measuring probe being used to measure the level of a medium, the electronic unit comprising: At least one first excitation electronic unit (11) is configured to emit a first excitation signal; and At least one second excitation electronic unit (12) is configured to emit a second excitation signal. Wherein, the first excitation signal is different from the second excitation signal, and The electronic units (10, 30) are configured to simultaneously transmit the first excitation signal and the second excitation signal to the level measuring probes (15, 34). The electronic units (10, 30) further include at least one first evaluation electronic unit (16) for evaluating conductive level measurements and at least one second evaluation electronic unit (17) for evaluating capacitive level measurements. The combined output signal of the level measurement probes (15, 34) serves as the input signal for both the first evaluation electronic unit (16) and the second evaluation electronic unit (17). The first evaluation electronic unit (16) is equipped with a first filter unit (18), which is configured to filter out a first output signal for conductive level measurement from the combined output signal. The second evaluation electronic unit (17) is equipped with a second filter unit (19), which is configured to filter out a second output signal for capacitive level measurement from the combined output signal.

2. The electronic unit (10, 30) according to claim 1, in, The at least one first excitation electronic unit (11) is configured to emit the first excitation signal for first level measurement, and The at least one second excitation electronic unit (12) is configured to emit the second excitation signal for the second level measurement.

3. The electronic unit (10, 30) according to claim 2, in, The first level measurement is a conductive level measurement, and The second level measurement is a capacitive level measurement.

4. The electronic unit (10, 30) according to any one of claims 1 to 3, wherein, The first excitation signal and the second excitation signal have different frequencies.

5. The electronic unit (10, 30) according to any one of claims 1 to 3, wherein, The first excitation electronic unit (11) is configured to emit a square wave signal and / or a sine wave signal as the first excitation signal.

6. The electronic unit (10, 30) according to claim 5, wherein, The square wave signal and / or the sine wave signal are used for conductive level measurement.

7. The electronic unit (10, 30) according to claim 5, wherein, The square wave signal and / or the sine wave signal are transmitted at a frequency of 5 kHz.

8. The electronic unit (10, 30) according to any one of claims 1 to 3, wherein, The second excitation electronic unit (12) is configured to emit a triangular wave signal and / or a sine wave signal and / or a square wave signal as the second excitation signal.

9. The electronic unit (10, 30) according to claim 8, wherein, The triangular wave signal and / or the sine wave signal and / or the square wave signal are used for capacitive level measurement.

10. The electronic unit (10, 30) according to claim 8, wherein, The triangular wave signal and / or the sine wave signal and / or the square wave signal are transmitted at a frequency of 355 kHz.

11. The electronic unit (10, 30) according to any one of claims 1 to 3, wherein, The first excitation electronic unit (11) and / or the second excitation electronic unit (12) include at least one direct digital synthesis unit to provide the first excitation signal and / or the second excitation signal.

12. The electronic unit (10, 30) according to any one of claims 1 to 3, wherein, The first excitation electronic unit (11, 31) and the second excitation electronic unit (12, 31) are configured to transmit the first excitation signal and the second excitation signal in such a way that the first excitation signal and the second excitation signal have the same arithmetic mean.

13. The electronic unit (10, 30) according to claim 1, in, The first filter unit (18) is configured as a digital filter unit and includes at least one bandpass filter unit having a center frequency corresponding to the first excitation signal, and / or The second filter unit (19) is configured as a digital filter unit and includes at least one bandpass filter unit having a center frequency corresponding to the second excitation signal.

14. The electronic unit (10, 30) according to claim 1, in, The first filter unit (18) is configured as a digital filter unit and includes at least one bandpass filter unit having a center frequency corresponding to the first excitation signal, and / or The second filter unit (19) is configured as a digital filter unit and includes at least one bandpass filter unit having a center frequency corresponding to the second excitation signal.

15. The electronic unit (10, 30) according to any one of claims 1 to 3, wherein, The electronic unit (10, 30) includes at least one first digital-to-analog converter (33), which is configured to convert at least one digital excitation signal of the electronic unit (10, 30) into an analog excitation signal, which can be transmitted as an analog excitation signal to the level measuring probe (15, 34).

16. The electronic unit (10, 30) according to claim 1, wherein, The electronic units (10, 30) include at least one second analog-to-digital converter (36), which is configured to convert the analog output signal of the level measuring probe (15, 34) into a digital output signal, which can be transmitted as a digital output signal to the evaluation electronic units (16, 17, 31).

17. The electronic unit (10, 30) according to any one of claims 1 to 3, wherein, The electronic units (10, 30) include a weighting unit configured to weight the measurement results of conductive level measurement and capacitive level measurement according to the medium-specific properties of the medium in which the level is being detected.

18. The electronic unit (10, 30) according to claim 17, wherein, The specific properties of the medium are the conductivity and / or dielectric constant of the medium at which the level is detected.

19. The electronic unit (10, 30) according to claim 17, wherein, One or more of the media-specific properties are determined from test signals and / or calibration signals.

20. A level measuring probe (15, 34) for measuring level, comprising at least one electronic unit (10, 30) according to any one of claims 1 to 19.

21. Use of the electronic unit (10, 30) according to any one of claims 1 to 19 in a level measuring sensor for measuring level.

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