Electrical measuring assembly
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Solution Overview
Problem
Existing electrical measuring assemblies for capacitive liquid measurement face challenges in maintaining accurate capacitance determination due to material contamination, stray fields, and the need for frequent recalibration, especially in food industry applications where stringent food safety regulations apply.
Innovation Solution
The use of stainless steel electrodes with insulating elements made from food-safe, chip-machineable glass ceramic materials that provide stable electrical insulation, minimize water absorption, and maintain consistent permittivity over temperature ranges, combined with strategically designed inlet and discharge openings to reduce stray fields and prevent contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional insulating materials are used, then manufacturing cost is reduced, but measurement precision deteriorates due to water absorption and permittivity variations
Solution Approach 1:
The patent specifies precise material parameters for the insulating elements: water absorption ≤0.05%, permittivity variation ≤30% (preferably ≤10%) over 20-200°C temperature range. These parameter constraints ensure measurement accuracy while providing clear material selection criteria that simplify the design process.
Solution Approach 2:
The patent employs glass ceramic as the insulating material, which combines the advantages of ceramic (low water absorption, stable permittivity) with the machinability of glass. This composite material approach resolves the contradiction by providing both measurement precision and ease of manufacturing.
2Measurement precision
If frequent recalibration is performed, then measurement precision is maintained, but loss of time increases
Solution Approach 1:
The patent uses glass ceramic insulating elements with exceptionally low water absorption (≤0.05%) and stable permittivity characteristics to pre-cushion against the factors that would require recalibration. This material selection prevents measurement drift before it occurs, eliminating the need for frequent recalibration and reducing time loss.
3Object-affected harmful factors
If additional coatings are applied to electrodes, then food safety is improved, but device complexity increases
Solution Approach 1:
The patent uses food-safe stainless steel (e.g., 1.4404, AISI 316L) for both the inner and outer electrodes, maintaining material homogeneity throughout the electrode structure. This eliminates the need for additional coatings while ensuring food safety compliance, thereby reducing device complexity.
4Ease of manufacture
If manufacturing tolerances are relaxed, then ease of manufacture is improved, but measurement precision deteriorates due to electrode misalignment
Solution Approach 1:
The patent employs glass ceramic insulating elements that provide uniform electrical insulation and mechanical support, creating an equipotential environment that compensates for minor manufacturing tolerances. This allows adequate alignment between electrodes while maintaining measurement precision through the stabilizing effect of the glass ceramic material.
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 configuration enhances the service properties of the measuring assembly by ensuring accurate capacitance measurement, reducing the need for frequent recalibration, and adhering to food safety regulations by using materials that prevent contamination and maintain consistent performance.
Implementation Method 1
the inner electrode is retained at the axial ends by a respective insulating element, wherein the insulating elements are formed of a food-safe material... glass ceramic... associated with good electrical insulation properties
Implementation Method 2
The property is exploited whereby the dielectric constant of frying oil or frying fat changes, the longer the frying oil or frying fat is in use. The dielectric constant thus influences the capacitance of a capacitor constituted by the outer electrode and the inner electrode, which capacitance can be determined electrically and/or electronically.
Implementation Method 3
the dielectric constant of frying oil or frying fat changes... the dielectric constant thus influences the capacitance
Implementation Method 4
the insulating elements are comprised of a material which absorbs no water... any impairment or contamination of the liquid flowing past, for example frying oil or frying fat, is avoidable, or can even be excluded altogether
Data Source
AI summary
In an electrical measuring assembly (1), in which an inner electrode (2) and an outer electrode (3), which form a measuring chamber (4) therebetween for a capacitive examination of a liquid flowing past, are formed from a food-safe stainless steel, the inner electrode (2) is supported at the axial ends (6, 7) thereof on the outer electrode (3) by insulating elements (10, 11), which are produced from a ceramic material or plastic material that can be machined and/or that has a permittivity that is temperature-independent in a working range and/or that is free of pores and/or does not absorb water.