Metal Detection via Superimposed Magnetic Fields and Voltage Minimization

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Solution Overview

Problem

Existing metal detectors are not simple or accurate enough for detecting metallic objects within workpieces during machining, and they often suffer from susceptibility to malfunctions and high manufacturing costs.

Innovation Solution

A measuring device with two transmission coils generating superimposed magnetic fields and a reception coil, controlled to minimize clock-synchronous AC voltage induced in the reception coil, allowing for differential and field-compensated measurements with reduced susceptibility to interference, using phase-shifted AC voltages for sensitive detection and potentially including multiple receiving coils for directional and size determination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If coil-based metal detectors with multiple transmitting coils are used to generate magnetic fields for detecting metallic objects, then the detection capability is improved, but the device complexity and manufacturing cost increase

Engineering Contradiction:
Improvedetection capabilityVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines the functions of multiple transmitting coils and a receiving coil into a single integrated measuring device. The control device coordinates the transmitting coils to generate magnetic fields that cancel each other out in the absence of a metallic object, while a receiving coil detects disturbances caused by metallic objects. This merging of multiple components into a coordinated system improves detection capability while managing device complexity through functional integration.

Inventive Principle:
Principle #5Merging (Combining)

2Measurement precision

If multiple transmitting coils are used to generate superimposed magnetic fields for field-compensated measurement, then the measurement accuracy is improved, but the manufacturing cost increases

Engineering Contradiction:
Improvemeasurement accuracyVSAvoidmanufacturing cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The control device in the patent implements a feedback mechanism that monitors the magnetic field generated by the transmitting coils and adjusts their operation to maintain field compensation. By using the receiving coil to detect the magnetic field environment and feeding this information back to the control device, the system achieves high measurement accuracy through dynamic adjustment, reducing the need for expensive precision components and simplifying manufacturing.

Inventive Principle:
Principle #23Feedback

3Reliability

If the measuring device is designed to minimize the AC voltage induced in the receiving coil through control of transmitting coils, then the susceptibility to malfunction is reduced, but the device complexity increases

Engineering Contradiction:
Improvesusceptibility to malfunctionVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The measuring device employs a self-service mechanism where the control device automatically adjusts the transmitting coils to minimize the AC voltage induced in the receiving coil. This self-regulating system uses the receiving coil's output to control the transmitting coils, creating a closed-loop system that reduces susceptibility to malfunction without requiring external intervention or complex additional components.

Inventive Principle:
Principle #25Self-service

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 cost-effective, high-sensitivity metal detector capable of accurately detecting metallic objects with reduced susceptibility to interference and manufacturing costs, enabling precise detection of metallic objects in workpieces during machining.

Implementation Method 1

two transmission coils (125, 130) for generating superimposed magnetic fields (B1, B2), a reception coil (135) in the area of the two magnetic fields

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

If there is a metallic object in the measuring range, the object is recognized due to its influence on the generated magnetic field

Methodology Applied
Scientific EffectMagnetic field interaction with metallic objects: Magnetic Field

Data Source

PatentEP2567264B1Detection of a metal or magnetic object
Publication Date: 2014.06.11 ROBERT BOSCH GMBH
  • EP2567264B1 patent drawingFigure 1
  • EP2567264B1 patent drawingFigure 2~4

AI summary

The invention relates to a measuring device for detecting a metal object, comprising two emission coils for producing superimposed magnetic fields, a receiving coil in the region of both magnetic fields and a control device for controlling the emission coils such that the value of a voltage, which is clock synchronised with the alternating voltages and which is induced in the emission coils, is minimised. Said control device is configured to detect the object when the ratio of the alternating voltages does not correspond to the ratio of the distances between the receiving coils and the emission coils.