CN-122016006-A - Material level measuring device

Abstract

The invention relates to a fill level measuring device for determining a fill level of a medium in a container, comprising a signal generating device configured to generate an electrical signal comprising a step function or a pulse function, a measuring line connected (in particular electrically connected) to the signal generating device and extending from a process connection into the medium and into the medium, wherein the measuring line is used for conducting the electrical signal into the container and into the medium, wherein the electrical signal is at least partially reflected at a surface of the medium and the reflected signal influences the electrical signal, and an evaluation unit configured to determine the fill level of the medium on the basis of the influenced electrical signal.

Inventors

• Boris Baldi Schwele
• THOMAS WEBER

Assignees

• 西克股份公司

Dates

Publication Date

20260512

Application Date

20251111

Priority Date

20241111

Claims (20)

1. 1. A level measurement device for determining a level of a medium in a container, the level measurement device comprising: A signal generating device configured to generate an electrical signal comprising a step function or a pulse function; A measuring line connected to the signal generating device and extending from the process connection to the medium and into the medium, wherein the measuring line is used for conducting the electrical signal into the container and towards the medium, wherein the electrical signal is at least partially reflected at the medium surface and the reflected signal influences the electrical signal, and An evaluation unit configured to determine a fill level of the medium based on the influenced electrical signal.
2. 2. The fill level measuring device as claimed in claim 1, wherein, The measurement line is electrically connected to the signal generating means.
3. 3. The fill level measuring device as claimed in claim 1, wherein, The evaluation unit is configured to determine a surrogate variable based on the affected electrical signal and to determine a level of the medium based on the surrogate variable, the surrogate variable being proportional to a time of flight of the electrical signal from the process connection back to the medium surface and/or to a distance between the medium surface and the process connection; The surrogate variable does not correspond to a time of flight of the electrical signal.
4. 4. A fill level measuring device as claimed in claim 3, wherein, The affected electrical signal has a pulse shape; The evaluation unit is configured to generate a square wave signal based on a pulse width of a pulse of the affected electrical signal and to determine the surrogate variable based on the square wave signal, the width of the square wave signal substantially corresponding to the pulse width of the affected electrical signal.
5. 5. The fill level measuring device as claimed in claim 4, wherein, The evaluation unit is configured to generate a square wave signal based on a pulse width of a first pulse of the affected electrical signal.
6. 6. The fill level measuring device as claimed in claim 4, wherein, The evaluation unit is configured to generate the square wave signal based on the affected electrical signal using a threshold filter, wherein the square wave signal takes on a substantially value of 0 if the affected electrical signal is smaller than a predetermined threshold value; The evaluation unit is configured to integrate the square wave signal using an integrator component to determine an integrated value and to determine a level of the medium based on the integrated value.
7. 7. The fill level measuring device as defined in claim 6, wherein, The evaluation unit is configured to define the predetermined threshold value in dependence of an impedance difference between a reference impedance representing an impedance of a portion of the measurement line not extending into the medium and a medium impedance representing an impedance of a portion of the measurement line extending into the medium.
8. 8. The fill level measuring device as defined in claim 6, wherein, The evaluation unit is configured to adjust the predetermined threshold of the threshold filter continuously or at predetermined time intervals.
9. 9. The fill level measuring device of claim 8, wherein, The evaluation unit is configured to decrease the predetermined threshold of the threshold filter continuously or at predetermined time intervals.
10. 10. The fill level measuring device as defined in claim 6, wherein, The evaluation unit includes a plurality of threshold filters having different thresholds.
11. 11. The fill level measuring device as defined in claim 6, wherein, The evaluation unit is configured to sample an integrated signal generated by integration of the square wave signal by means of an ADC with a sampling frequency of less than 10 MHz, less than 1 MHz, less than 100 kHz, less than 10 kHz or less than 1 kHz to determine the integrated value.
12. 12. The fill level measuring device as claimed in claim 1, wherein, The measurement line comprises a coaxial cable.
13. 13. The fill level measuring device as claimed in claim 1, wherein, The electrical signal comprises a plurality of square wave pulses and the affected electrical signal comprises a plurality of pulses; The evaluation unit is configured to determine a DC component of the affected electrical signal and to determine a level of the medium based on the DC component of the affected electrical signal.
14. 14. The fill level measuring device of claim 13, wherein, The affected electrical signal comprises a plurality of pulses of the same type.
15. 15. The fill level measuring device of claim 13, wherein, The signal generating means is configured to generate square wave pulses of the electrical signal at variable time intervals.
16. 16. The fill level measuring device as claimed in claim 1, wherein, The reference impedance is greater than the dielectric impedance.
17. 17. The fill level measuring device of claim 16, wherein, The reference impedance is 5, 10, 12 or 15 times greater than the dielectric impedance.
18. 18. The fill level measuring device as claimed in claim 1, wherein, The measuring line is arranged on the same circuit board together with the evaluation unit and the signal generating device.
19. 19. The fill level measuring device of claim 18, wherein, The measurement line is one of a coplanar line and a microstrip line.
20. 20. A method for determining a level of a medium in a container, comprising the steps of: An electrical signal in the form of a step function is generated by means of a signal generating means, Conducting the electrical signal into the container and into the medium via a measuring line, wherein the measuring line extends into the medium and into the medium, Reflecting a portion of the electrical signal from the surface of the medium, wherein the reflected signal affects the electrical signal, an The fill level of the medium is determined by means of an evaluation unit on the basis of the influenced electrical signals.

Description

Material level measuring device Technical Field The invention relates to a fill level measuring device for determining a fill level (FILLING LEVEL) of a medium in a container. Background In various industrial applications, it is a common requirement to accurately determine the level of a tank. In this regard, there are different techniques available to address this problem. For example, the level may be determined using an optical, radar-based, capacitive or conductive sensor, tuning fork, float or wired TOP (time-of-flight) method. In the wired TOF direction, the electrical pulse is sent out through a cable that extends into the tank liquid. Since the cable has different effective impedances in the part not extending into the liquid and in the part extending into the liquid, the electrical pulse transmitted through the cable will be reflected at the liquid level, i.e. at the boundary between the two different impedances, so that the level of the tank can be deduced based on the time of flight of the electrical pulse from the process connection to the liquid level and the time of flight of the reflected signal from the liquid level back to the process connection. However, the evaluation of pulses in the wired TOF method places high demands on the transmitting and receiving devices, as they have to provide high resolution (typically in the picosecond range), which increases complexity and cost. A further disadvantage is that a number of excitation signals in succession are often required to record the time of flight, which will have a negative impact on the energy consumption. Furthermore, the existing methods will cause high-frequency interference of a large number of emissions, since a part of the high-frequency pulse signal will radiate out through the measurement probe acting as an antenna. Thus, such applications are generally limited to use in metal containers. Disclosure of Invention The object of the present invention is to remedy the above-mentioned drawbacks and to provide an improved level measuring device for determining the level of a medium in a container and a corresponding method. This object is met by the subject matter of the independent claims. A first aspect of the invention relates to a level measurement device for determining a level of a medium in a container, the level measurement device comprising: A signal generating device configured to generate an electrical signal comprising a step function or a pulse function; A measuring line which is connected (in particular electrically connected) to the signal generating device and extends or can extend from the process connection into the medium and into the medium, wherein the measuring line serves for conducting an electrical signal into the container and into the medium, wherein the electrical signal is preferably at least partially reflected at the medium surface and the reflected signal influences the electrical signal; An evaluation unit configured to determine a level of the medium based on the influenced electrical signal. The invention is based on the insight that the reflection of an electrical signal at the surface of the medium affects or alters the original electrical signal and that this change is reflected in the form of the affected electrical signal, so that the time of flight of the electrical signal and thus the level of the medium can be determined on the basis of the affected electrical signal, in particular indirectly. In particular, the fill level of the medium can thus be determined without directly measuring or determining the time of flight (time of flight) of the electrical signal to the surface of the medium and back. The affected electrical signal is in particular the step response or impulse response of the system to the applied input signal. When referring herein to the time of flight of an electrical signal, unless otherwise indicated, it refers to the time of flight of the electrical signal from the process connection (or from the signal generating device) to the surface of the medium, as well as the time of flight of the reflected signal from the surface of the medium back to the process connection (and thus to the evaluation unit). For example, the signal generating means is a voltage source which generates a voltage which has at least partly the form of a step function or a pulse function and which is fed to the level measuring means. In particular, the signal generating device is capable of rapidly switching on or feeding an electrical signal to the system, i.e. with rise times shorter than 10 ns, 1 ns or 100 ps. For example, it is thereby ensured that the fill level measuring device can perform measurements with a suitable measurement accuracy and resolution. For example, a rapid increase in the electrical signal may also be generated by switching a switch to feed a constant electrical signal to the system "suddenly". For example, the switch may be configured as part of the signal generating means and m