Capacitive Adhesive Level Sensor for Precision Control

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Solution Overview

Problem

Existing methods for monitoring and regulating adhesive levels in storage containers are not precise enough for small changes and often require contact or lengthy warm-up phases, leading to unproductive waiting times and high energy consumption.

Innovation Solution

A capacitive level sensor that determines adhesive levels through a variable electric field, allowing for accurate measurement without contact and reducing preparation times by adjusting its immersion depth or distance from the adhesive, using two concentrically arranged electrodes with a galvanically isolated air gap to generate a uniform capacitive field.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If contact-based sensors are used to determine adhesive levels, then measurement reliability is improved, but preparation time increases due to required warm-up phases

Engineering Contradiction:
Improvemeasurement reliabilityVSAvoidpreparation time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces contact-based mechanical/sensor systems with a capacitive field-based measurement system. The capacitive sensor determines adhesive level through a variable electric field without physical contact, eliminating the need for warm-up phases while maintaining measurement reliability. This substitution of measurement principle directly resolves the contradiction between reliable measurement and preparation time.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Quantity of substance

If large amounts of adhesive are maintained in storage containers, then sufficient adhesive is available for production, but energy consumption increases for heating and preparation

Engineering Contradiction:
Improveadhesive quantityVSAvoidenergy consumption
Core Design Contradiction:
Quantity of substanceVSUse of energy by moving object

Solution Approach 1:

The capacitive level sensor provides continuous feedback on the actual adhesive level in the storage container. This feedback enables the control system to monitor adhesive quantity in real-time and trigger refilling operations at optimal moments. By maintaining adhesive levels based on actual consumption rather than keeping large reserves, the system reduces the quantity of adhesive that requires continuous heating, thereby lowering energy consumption while ensuring sufficient adhesive availability for production.

Inventive Principle:
Principle #23Feedback

3Measurement precision

If sensors dip into the filling level for calibration, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improvefilling level measurement precisionVSAvoidsensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex calibrated contact sensors with a simpler capacitive field-based sensor that determines adhesive level without physical immersion. The capacitive sensor measures the dielectric properties of the adhesive through the air gap, eliminating the need for mechanical calibration procedures and complex sensor positioning systems. This substitution maintains measurement precision while significantly reducing device complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Stability of the object's composition

If adhesive is heated for extended periods to ensure liquidity, then adhesive flow properties are improved, but productivity decreases due to unproductive waiting times

Engineering Contradiction:
Improveadhesive liquidityVSAvoidproduction productivity
Core Design Contradiction:
Stability of the object's compositionVSProductivity

Solution Approach 1:

The capacitive level sensor enables preliminary detection of adhesive levels before critical situations arise. By continuously monitoring the adhesive level and predicting when refilling will be needed, the system can plan refilling operations during optimal moments rather than during production interruptions. This preliminary action allows the system to maintain adhesive liquidity through targeted heating only when needed, rather than continuous extended heating, thereby improving productivity while ensuring adequate adhesive flow properties.

Inventive Principle:
Principle #10Preliminary action

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 quick and precise determination of adhesive levels, reducing preparation times and energy consumption by allowing only the necessary adhesive to be maintained, and facilitating efficient refilling and heating processes.

Implementation Method 1

capacitive level sensor that determines adhesive levels through a variable electric field

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

two concentrically arranged electrodes with a galvanically isolated air gap to generate a uniform capacitive field

Methodology Applied
Scientific EffectElectric Field: Electric Field

Data Source

PatentEP2503425B1Method and device for controlling/regulating a fill level
Publication Date: 2020.10.28 HOMAG GMBH
  • EP2503425B1 patent drawingFigure 1
  • EP2503425B1 patent drawingFigure 2

AI summary

The method involves using a metering device for application of an adhesive (10) by a roller on the surface of workpiece or a strip-shaped sheet. A sensor (15) projected in a container has end immersed in the adhesive or end projecting into the container by the adhesive. A variable electric field (23) is stored at end of adhesive immersed sensor or the adhesive spaced apart end of sensor corresponding to distance with respect to adhesive, for maintaining predetermined level of adhesive and appropriate filling of container. An independent claim is included for apparatus for controlling/regulating filling level of adhesive used for adhering strip paths or surfaces of workpieces.