Capacitive Fill Level Sensor With Voltage Divider Electrode
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Solution Overview
Problem
Existing capacitive filling level measurement devices require complex structures due to multiple electrical capacitors and often have limited measurement ranges, especially when the permittivity of the filling medium is unknown, necessitating additional reference measuring elements.
Innovation Solution
A device with a first and second measuring element, where the second measuring element is designed as a level-independent voltage divider with a potential gradient, allowing for capacitively measuring the filling level without determining the permittivity of the filling medium, using a capacitor arrangement with a first and second electrode and a voltage generating device to apply alternating electrical voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple electrical capacitors are used to measure filling level when permittivity is unknown, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The patent combines two measuring elements (first and second measuring elements) into a single integrated capacitor arrangement. The first measuring element serves as one electrode while the second measuring element serves as the other electrode, merging what would traditionally be separate capacitor structures into one unified device that can determine both filling level and permittivity simultaneously.
Solution Approach 2:
The capacitor arrangement performs multiple functions: it measures filling level through capacitance changes and simultaneously determines permittivity of the filling medium. This multi-functionality eliminates the need for separate reference measuring elements or additional capacitors that would otherwise be required.
2Measurement precision
If reference measuring elements are added to determine permittivity, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the functions of level measurement and permittivity determination into a single capacitor arrangement with two measuring elements. The evaluation device processes signals from both elements simultaneously to extract both filling level and permittivity information, eliminating the need for separate reference measuring elements.
Solution Approach 2:
The capacitor arrangement uses its own structure (first and second measuring elements) to self-determine both filling level and permittivity without requiring external reference components. The system serves itself by using the interaction between the two measuring elements to extract multiple parameters from the same sensing structure.
3Reliability
If decoupling of electrical capacitors is implemented, then measurement reliability is improved, but device complexity increases
Solution Approach 1:
The evaluation device acts as an intermediary that processes the coupled signals from both measuring elements and extracts accurate filling level information. Rather than physically decoupling the capacitors, the evaluation device mathematically separates the contributions of each measuring element to eliminate mutual interference effects.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate and independent measurement of the filling level across a wide range, regardless of the filling medium's permittivity, simplifying the device structure and expanding measurement capabilities.
Implementation Method 1
Devices and methods for capacitively measuring a filling level of a filling medium in a filling volume that can be filled with a filling medium are known in principle. Corresponding devices or methods are based on the principle of evaluating the electrical capacitance, which changes as a function of the filling level of a filling medium
Implementation Method 2
The complex relative permittivity (hereinafter abbreviated as permittivity) of the filling medium, the real part of which reflects the dielectric constant of the filling medium and the imaginary part of which reflects the (specific) electrical conductivity of the filling medium
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a device (1) for capacitively measuring a fill level of a filling medium (2) in a filling volume (3) that can be filled with a filling medium, comprising: a first measuring element (5), a second measuring element (6), the second measuring element (6) being designed in such a way that a potential gradient is formed between a first portion (6a) of the second measuring element (6) and a second portion (6b) of the second measuring element (6); a voltage-generating apparatus (7), which is associated with the second measuring element (6) and which is designed to generate a first voltage (U1) and a second voltage (U2), which is optionally different from the first voltage (U1), and to apply the same to the second measuring element (6); a control apparatus (8), which is associated with the voltage-generating apparatus (7) and which is designed to control the operation of the voltage-generating apparatus (7) in such a way that the first voltage (U1) and the second voltage (U2) are alternately applied to the first portion (6a) and the second portion (6b) of the second measuring element (6).