Capacitive Coupling Element for Fill Level Sensor Signal Integrity

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Solution Overview

Problem

Capacitive field devices face challenges in maintaining reliable and durable electrical connections between the housing and electronics unit, leading to potential measurement inaccuracies and electromagnetic compatibility issues due to susceptibility to disturbance signals and wear from contact types like sliding contacts.

Innovation Solution

A capacitive coupling element is introduced to establish a conductive and capacitive connection between the housing and electronics unit, ensuring a short electrical current loop and maintaining signal integrity even if the conductive contact degrades, utilizing a high-frequency exciter signal that enhances capacitive coupling with frequency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional electrical contacts (sliding contacts, plug contacts, soldered connections) are used to connect the housing and electronics unit, then electrical connection is established, but the connection is susceptible to wear, degradation, and disturbance signals leading to measurement inaccuracies

Engineering Contradiction:

Improveconnection reliabilityVSAvoidsusceptibility to disturbance signals

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical electrical contact system (sliding contacts, plug contacts, soldered connections) with an electromagnetic field-based capacitive coupling system. The coupling element creates a capacitive coupling between the housing and electronics unit, eliminating direct mechanical contact and its associated problems of wear, degradation, and susceptibility to disturbance signals.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The coupling element acts as an intermediary component that establishes capacitive coupling between the housing and electronics unit. This intermediary structure enables signal transmission while isolating the electrical components, preventing direct electrical contact and its associated harmful effects.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If conventional electrical contacts are used, then electrical connection is established, but electromagnetic emissions occur affecting electromagnetic compatibility

Engineering Contradiction:

Improveelectrical connection stabilityVSAvoidelectromagnetic emissions

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the mechanical electrical contact system that generates electromagnetic emissions with a capacitive coupling system. The coupling element creates an electric field-based connection that significantly reduces electromagnetic radiation and improves electromagnetic compatibility while maintaining stable signal transmission.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If high-frequency exciter signal is used, then capacitive coupling is enhanced, but the requirement for stable capacitive coupling increases

Engineering Contradiction:

Improvesignal transmission accuracyVSAvoidcapacitive coupling stability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent utilizes the relationship between frequency and capacitive coupling by applying high-frequency exciter signals. The capacitive coupling element is designed to maintain stable coupling at these high frequencies, and the system evaluates response signals at multiple frequencies to optimize measurement precision while ensuring coupling stability.

Inventive Principle:

Principle #35Parameter changes

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

The solution provides a robust, stable, and simple contacting method that reduces electromagnetic interference and ensures accurate signal transmission, maintaining measurement quality and electromagnetic compatibility.

Implementation Method 1

a coupling element (11) which is arranged and embodied in such a manner at least at times to establish a conductive connection between at least one portion of the housing (8) and at least one component of the electronics unit (7) and at least at times to effect a capacitive coupling between the two components

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

utilizing a high-frequency exciter signal that enhances capacitive coupling with frequency

Methodology Applied

Scientific EffectCapacitive coupling enhancement with frequency: Capacitance

Data Source

PatentUS10895488B2Coupling element for a capacitive fill level measuring device

Publication Date: 2021.01.19 ENDRESS & HAUSER GMBH & CO KG

AI summary

Apparatus for capacitive determining and/or monitoring of at least one process variable of a medium in a container, comprising at least one sensor unit with at least one sensor electrode, a housing and an electronics unit, wherein the electronics unit is embodied to supply the sensor unit with a high-frequency exciter signal, to receive a response signal from the sensor unit, and to provide at least from the response signal information concerning the fill level of medium in the container. The apparatus includes, furthermore, a coupling element, which is arranged and embodied in such a manner at least at times to establish a conductive connection between at least one portion of the housing and at least one component of the electronics unit and at least at times to effect a capacitive coupling between the two components.