Inductive Foil Detector Damping Thresholds

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Solution Overview

Problem

In the manufacturing of accumulators, existing technologies face challenges in accurately detecting the number of foils using inductive sensors, leading to undefined situations during automated production, particularly when one or multiple foils stick together, which is critical for high quantities and low costs.

Innovation Solution

An inductive foil detector with an oscillating circuit generating an electromagnetic alternating field, causing eddy currents in foils, and an evaluation device that determines damping thresholds to differentiate between the presence of one, two, or no foils, outputting digital signals for easy processing by a programmable logic controller.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If inductive sensors are used to detect the number of foils, then foil detection is possible, but accurate determination of the number of foils is difficult leading to undefined situations

Engineering Contradiction:
Improvefoil detection accuracyVSAvoidproduction process reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent changes the evaluation parameters by introducing multiple threshold values (first threshold, second threshold) for damping values. Instead of using a single threshold, the system compares damping values against multiple thresholds to accurately determine the number of foils. This parameter change enables reliable distinction between one foil, multiple foils, and no foil scenarios, resolving the measurement precision and reliability contradiction.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If analog measurement signals are used for foil detection, then foil presence can be detected, but evaluation and further processing is complex and expensive

Engineering Contradiction:
Improvefoil detection capabilityVSAvoidevaluation system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent transforms the complex analog measurement evaluation into a simple digital threshold comparison system. By changing from continuous analog signal processing to discrete digital threshold comparisons (comparing damping values against first and second thresholds), the system achieves accurate foil counting with minimal computational complexity. This parameter change from analog to digital evaluation methodology resolves the contradiction between detection capability and system complexity.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces complex analog signal processing mechanisms with a simpler digital evaluation approach. Instead of using expensive analog cards for signal evaluation, the system uses a programmable logic controller with digital threshold comparisons. This substitution of evaluation methodology reduces device complexity while maintaining detection precision.

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

3Ease of operation

If vacuum gripper bends the film to detach second film, then single film gripping is improved, but additional mechanical complexity is introduced

Engineering Contradiction:
Improvesingle film grippingVSAvoidgripper mechanism complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent replaces mechanical bending mechanisms with an inductive detection system. Instead of relying on mechanical bending to detach films, the system uses electromagnetic induction to detect the number of foils gripped. The oscillating circuit generates an electromagnetic field that interacts with the conductive layers of the foils, providing non-contact detection. This substitution eliminates the need for complex mechanical bending mechanisms while achieving the same operational goal.

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

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 simple and inexpensive evaluation of foil detection, preventing incorrect accumulator assembly by accurately determining the number of foils, ensuring proper handling and reducing errors in automated production lines.

Implementation Method 1

An inductive foil detector according to the invention has an oscillating circuit for generating an electromagnetic alternating field. If there is a foil with a metallic layer in this electromagnetic alternating field generated by the oscillating circuit, then an eddy current is excited in this foil by the electromagnetic alternating field of the oscillating circuit

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

an eddy current is excited in this foil by the electromagnetic alternating field of the oscillating circuit, which in turn causes a field that opposes the exciting electromagnetic alternating field of the oscillating circuit. The oscillating circuit is accordingly damped by the presence of the foil

Methodology Applied
Scientific EffectEddy current: Eddy Currents

Data Source

PatentEP2921853B1Inductive foil detector
Publication Date: 2016.09.28 SICK AG
  • EP2921853B1 patent drawingFigure 1~3
  • EP2921853B1 patent drawingFigure 4~5

AI summary

An inductive film detector for detecting the number of adjacent films, comprising a resonant circuit for generating an alternating electromagnetic field and an evaluation device for determining the damping of the resonant circuit, configured such that, upon exceeding a first predetermined damping threshold, it assumes the presence of a single film at a predetermined detection distance; upon falling below the first threshold, it assumes the presence of two films at the predetermined detection distance; and upon falling below a second predetermined threshold, which is smaller than the first threshold, it assumes a state without any film at the detection distance. The invention further relates to a method for determining the number of adjacent films.