Multi-Electrode Capacitive Sensor for Adhesion-Resistant Fill Level Measurement

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Solution Overview

Problem

Capacitive level measurement technologies face challenges in accurately measuring fill levels in containers with varying geometries and materials due to adhesion issues, electrostatic effects, and non-linearities, leading to unreliable results and frequent adjustments, especially with highly viscous liquids and bulk materials.

Innovation Solution

A method and device utilizing a sensor with at least three electrically insulated electrodes that can operate in multiple modes, applying different potentials to the electrodes and the container wall to minimize adhesion influences and ensure accurate measurements across various container types and materials, including non-conductive containers, by using a shielding mechanism to protect the measuring field.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single electrode sensor is used for capacitive level measurement, then the device structure is simple, but measurement reliability deteriorates due to adhesion and electrostatic effects

Engineering Contradiction:
Improvesensor structureVSAvoidmeasurement reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The sensor is divided into multiple electrodes (at least three) that are electrically insulated from each other. These electrodes work together in a coordinated manner to create a measurement system that overcomes the limitations of a single electrode, specifically addressing adhesion and electrostatic effects by distributing the measurement function across multiple elements.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements multiple measurement modes that can be dynamically selected based on the application requirements. The system can switch between different operational configurations (e.g., different electrode combinations and potential applications) to adapt to varying measurement conditions, thereby maintaining high reliability across diverse scenarios.

Inventive Principle:
Principle #15Dynamics

2Device complexity

If conventional capacitive measurement is used, then the setup is simple, but measurement precision deteriorates due to non-linearities from container geometry and material properties

Engineering Contradiction:
Improvemeasurement setupVSAvoidlevel measurement precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

By segmenting the measurement function across multiple electrodes, the system can capture more information about the capacitive field distribution. This enables better compensation for non-linear effects caused by container geometry and material properties, as different electrode pairs can be used to cross-validate measurements and reduce systematic errors.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies different potentials to different electrodes and implements multiple measurement modes that vary the electrical parameters of the system. By changing these parameters dynamically, the system can optimize measurements for different container geometries and material properties, thereby improving precision without requiring a completely complex setup.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If frequent adjustments are made to compensate for adhesion and material variations, then measurement precision is maintained, but productivity deteriorates due to operational interruptions

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidoperational efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The system is designed with multiple electrodes and measurement modes configured in advance to handle various measurement conditions. By having these options pre-established, the system can automatically adapt to different materials and container types without requiring frequent manual adjustments, thereby maintaining precision while avoiding operational interruptions.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The multi-electrode system with multiple measurement modes enables automatic compensation for adhesion and material variations. The system self-adjusts by selecting appropriate electrode combinations and measurement configurations based on the detected conditions, eliminating the need for manual intervention and maintaining both precision and productivity.

Inventive Principle:
Principle #25Self-service

4Ease of manufacture

If a robust single-electrode sensor is used, then ease of manufacture is high, but adaptability deteriorates for different container types and materials

Engineering Contradiction:
Improvesensor manufacturingVSAvoidcontainer and material compatibility
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The sensor is manufactured as a modular multi-electrode assembly where each electrode can be independently configured. This segmentation allows the same basic sensor structure to be adapted to different container types and materials by simply changing which electrodes are activated and how they are configured, without requiring complete redesigns for each application.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent creates a universal sensor platform with at least three electrodes that can perform multiple measurement functions. By implementing multiple measurement modes that utilize different electrode combinations, a single sensor design can adapt to various container geometries and material properties, achieving versatility while maintaining manufacturing simplicity through standardized electrode structures.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 flexible and accurate capacitive level measurement in containers of different shapes and materials, reducing the need for frequent adjustments and improving measurement reliability by accounting for container geometry, adhesion, and material characteristics, while allowing for continuous monitoring.

Implementation Method 1

The container wall and the electrode form a capacitor arrangement. The electrical field of this capacitor arrangement fills the entire volume of the container.

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

If there is a linear connection between filling height and volume increase, this statement is easily possible... Since all technical products have a higher dielectric effect than air, which is referred to as permittivity, the capacitance value... continuously increased with the container filling.

Methodology Applied
Scientific EffectDielectric permittivity: Dielectric Permittivity

Implementation Method 3

A method and device utilizing a sensor with at least three electrically insulated electrodes that can operate in multiple modes, applying different potentials to the electrodes and the container wall to minimize adhesion influences and ensure accurate measurements... by using a shielding mechanism to protect the measuring field.

Methodology Applied
Scientific EffectElectromagnetic shielding: Faraday Cage

Data Source

PatentEP2759812B1Method and apparatus for capacitative fill level measurement of liquids or bulk materials
Publication Date: 2018.01.17 RECHNER IND ELEKTRONIK
  • EP2759812B1 patent drawingFigure 1
  • EP2759812B1 patent drawingFigure 2a
  • EP2759812B1 patent drawingFigure 2b

AI summary

The method involves applying different potentials (4, 9, 10) to respective first, second and third electrodes (5, 5', 5'') of a measuring sensor (8) in a measuring mode, where the third electrode is operated as a guard electrode. One of the potentials is applied to one of the electrodes in another measuring mode, and another potential is applied to an electrically conducting container wall or to an auxiliary electrode arranged within a container (2). Fill level measurement of liquids and/or bulk materials in the container is carried out in the former mode or in the latter mode. An independent claim is also included for a device for capacitive fill level measurement of liquids and/or bulk materials in a container.