Strip Electrodes for Magnetic-Inductive Flow Meters

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Solution Overview

Problem

Magnetic-inductive flowmeters face limitations in the design and functionality of their measuring electrodes, particularly in terms of electrical conductivity and adhesion to the insulating cover layer, which affects the accuracy and reliability of flow, conductivity, and fill level measurements.

Innovation Solution

The measuring electrodes are designed as strips with direct galvanic contact to the flowing medium, made from materials with significantly higher electrical conductivity than the cover layer, utilizing extrinsic or intrinsic conductivity enhancements, and integrated into the cover layer for a smooth flow channel, with optional additional reference electrodes and multiple electrode arrangements for improved measurement accuracy and reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the measuring electrodes are made from materials with significantly higher electrical conductivity than the cover layer, then the measurement accuracy is improved, but the manufacturing complexity increases

Engineering Contradiction:
Improveflow measurement accuracyVSAvoidelectrode integration difficulty
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent applies composite materials by integrating measuring electrodes made of highly conductive materials (such as metals or conductive polymers) into the insulating cover layer. This composite structure combines the electrical insulation properties of the cover layer with the high electrical conductivity of the electrodes, enabling accurate flow measurements while maintaining the protective function of the cover layer.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent implements local quality by creating regions of different electrical conductivity within the cover layer structure. The measuring electrodes are positioned at specific locations where high electrical conductivity is required for voltage detection, while the surrounding cover layer maintains its insulating properties. This localized differentiation optimizes measurement accuracy without compromising the overall insulating function.

Inventive Principle:
Principle #3Local quality

2Reliability

If the measuring electrodes are designed as strips with direct galvanic contact to the flowing medium, then the conductivity detection is improved, but the adhesion to the insulating cover layer becomes more challenging

Engineering Contradiction:
Improveconductivity measurement reliabilityVSAvoidelectrode-adhesion strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent uses an intermediary approach by introducing adhesive layers or surface treatment mechanisms between the measuring electrodes and the insulating cover layer. This intermediary layer or treatment enables strong adhesion between the conductive electrodes and the insulating cover, ensuring that the electrodes remain securely positioned while maintaining their electrical conductivity for reliable measurements.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If multiple electrode arrangements are used for improved measurement accuracy, then the measurement robustness is enhanced, but the device complexity increases

Engineering Contradiction:
Improveflow and level measurement accuracyVSAvoidelectrode arrangement complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the measuring system into multiple electrode segments arranged at different positions within the cover layer. These segmented electrodes can be independently positioned and configured to detect flow characteristics at multiple locations, enabling more accurate and robust measurements while allowing modular design and assembly.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements multi-functionality by designing the electrode arrangements to perform multiple measurement functions simultaneously. The same electrode structure can detect both flow rate and fill level, or conductive properties, reducing the need for separate dedicated sensors for each measurement type and thereby managing device complexity.

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

This design enhances the functional and manufacturing advantages of magnetic-inductive flowmeters by ensuring higher electrical conductivity of the electrodes relative to the cover layer and the flowing medium, leading to improved measurement accuracy and robustness, including better conductivity and fill level detection.

Implementation Method 1

According to Faraday's law of induction, an electric field strength perpendicular to the flow direction and perpendicular to the magnetic field is generated in a flowing medium that carries charge carriers and flows through a magnetic field

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the measuring voltage can be tapped galvanically or capacitively at the measuring electrodes

Methodology Applied
Scientific EffectGalvanic contact: Conduction (electrical)

Implementation Method 3

the measuring voltage can be tapped galvanically or capacitively at the measuring electrodes

Methodology Applied
Scientific EffectCapacitive coupling: Capacitance

Data Source

PatentEP2192390B1Magnetic-inductive flow measuring apparatus
Publication Date: 2021.06.16 KROHNE AG
  • EP2192390B1 patent drawingFigure 1
  • EP2192390B1 patent drawingFigure 2
  • EP2192390B1 patent drawingFigure 3

AI summary

The magnetic-inductive flow meter has a measuring line with a magnetic field generating device for generating a magnetic field partially penetrating the measuring line. Two measuring electrodes (3) are provided for detecting and intercepting a measuring voltage induced in a flowing medium. The measuring electrodes are formed like strips, and have electrically conductive and galvanic contact with the flowing medium. The electrodes are made of Teflon (RTM: fluoropolymer) polymer or rubber. An independent claim is included for a method for manufacturing a magnetic-inductive flow meter.