Multi-Mode Fill Level Sensor for Conductive and Non-Conductive Media
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Solution Overview
Problem
Existing fill level monitoring technologies face challenges with media having low electrical conductivity, as conductive methods struggle with non-conductive media, and capacitive methods face issues with high conductivity and adhering media, leading to measurement inaccuracies and resolution limitations.
Innovation Solution
A multi-sensor device capable of alternating between capacitive and conductive operating modes, using a single electronic unit with square-wave and triangular signals for excitation, and incorporating a guard electrode to prevent deposits, allowing for high measurement resolution and medium property monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If capacitive measuring method is used for non-conductive media, then measurement capability is improved, but measurement resolution deteriorates due to insulation impedance
Solution Approach 1:
The patent applies dynamic switching between two operating modes (conductive and capacitive) based on the electrical conductivity of the medium. The system automatically selects the appropriate measurement mode to optimize both measurement capability and resolution, resolving the contradiction by making the measurement system adaptive rather than static.
Solution Approach 2:
The patent changes the measurement parameters (switching between conductive and capacitive modes) based on the medium's electrical conductivity. By adjusting the measurement approach according to the medium properties, the system achieves high resolution in both conductive and non-conductive scenarios.
2Measurement precision
If conductive measuring method is used for conductive media, then measurement resolution is improved, but measurement capability deteriorates for non-conductive media
Solution Approach 1:
The patent creates a universal measuring device that can operate in both conductive and capacitive modes, making it applicable to both conductive and non-conductive media. This multi-functionality resolves the contradiction by enabling the same device to achieve high resolution across different medium types.
Solution Approach 2:
The system dynamically switches between conductive and capacitive measurement modes based on the medium's conductivity, allowing the device to maintain high measurement capability across varying conditions while preserving resolution in each specific mode.
3Adaptability or versatility
If probe insulation is used for capacitive measurement of conductive media, then measurement capability is improved, but measurement resolution deteriorates due to insulation impedance
Solution Approach 1:
The patent dynamically selects between insulated (capacitive) and non-insulated (conductive) measurement approaches based on medium conductivity. For conductive media, the system switches to conductive mode without insulation, eliminating the resolution-deteriorating effect while maintaining measurement capability.
Solution Approach 2:
The measurement parameters are changed based on medium properties: insulation is applied only when measuring non-conductive media in capacitive mode, while conductive media are measured without insulation in conductive mode, optimizing both capability and resolution.
4Reliability
If guard electrode is used to prevent deposits, then reliability is improved, but device complexity increases due to additional components
Solution Approach 1:
The patent combines the guard electrode function with the existing measurement electrode structure, integrating deposit prevention into the core measurement component rather than adding a completely separate system. This merging approach improves reliability while minimizing the increase in device complexity.
Solution Approach 2:
The measuring electrode serves dual functions: primary level measurement and guard electrode function for deposit prevention. This multi-functionality improves reliability through deposit prevention while avoiding the complexity increase that would result from completely separate systems.
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 independent monitoring of fill levels regardless of medium electrical properties, achieving high measurement resolution and minimizing the impact of deposits, with automatic adjustment to changing media conditions.
Implementation Method 1
The fill level of the medium is determined from the capacitance of the capacitor formed by a probe electrode and the wall of the container or a second electrode. Depending on the conductivity of the medium, either the medium itself or a probe insulation forms the dielectric of the capacitor.
Implementation Method 2
The fill level is monitored by detecting whether there is electrical contact between a sensor electrode and the wall of a conductive container or a second electrode via the conductive medium.
Data Source
Figure 1
Figure 2
Figure 3a~3c
AI summary
A method for monitoring a predetermined filling level of a medium (3) in a container (2) with at least one measuring probe (1) and an electronic unit (7), wherein the measuring probe (1) is operated alternately in the conductive and in the capacitive operating mode, wherein the measuring probe (1) is subjected to an excitation signal, which excitation signal is composed of two different, temporally alternately consecutive periodic partial signals, wherein the first periodic partial signal for the conductive operating mode is generated in a first time interval and the second periodic partial signal for the capacitive operating mode is generated in a second time interval, wherein it is determined from the response signal, which is obtained by the measuring probe (1) and is dependent on the current partial signal, in accordance with the capacitive or conductive operating mode, whether the predetermined filling level has been reached, and a message is generated if the filling level exceeds or falls short of said filling level.