Underground Detection Device Shielding with Metal Sheet

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Solution Overview

Problem

Existing devices for detecting electrically conductive objects in underground substrates are influenced by electrically conductive foreign and interfering objects, such as operator-worn items, which affect measurement accuracy.

Innovation Solution

A device with a metal sheet in its housing separates the magnetic coil device from the control and evaluation devices, using the metal sheet to reduce the influence of electrically conductive foreign and interfering objects by spatially arranging the components in a way that the magnetic coil is on the underside and the control and evaluation devices are on the top side, with the metal sheet's conductivity and permeability selected to minimize interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the magnetic coil device is spatially separated from the control and evaluation devices (as in the Profometer PM-6), then the influence on measurement results from electrically conductive materials within the magnetic field is reduced, but the measurement results are still influenced by electrically conductive foreign objects such as wristwatches or rings worn by the operator

Engineering Contradiction:
Improvemeasurement results accuracyVSAvoidinfluence from electrically conductive foreign objects
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

A metal sheet is introduced as an intermediary element between the magnetic coil device and the operator's body. This metal sheet acts as a shield that interferes with the magnetic field interaction between the measurement probe and electrically conductive foreign objects on the operator's body, thereby reducing their harmful influence on measurement results

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If all device components are arranged in one housing, then the device structure is simplified and compact, but electrically conductive components within the housing may influence measurement results

Engineering Contradiction:
Improvedevice structureVSAvoidmeasurement results accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The housing interior is segmented into different regions by the metal sheet. The metal sheet creates distinct zones: one containing the magnetic coil device and another containing the control and evaluation devices. This segmentation prevents electrically conductive components in the control and evaluation sections from interfering with the magnetic field in the measurement section

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The metal sheet serves as a mediating structure that physically separates and electrically isolates different device components within the single housing. It acts as a barrier that prevents electromagnetic interference between the control/evaluation electronics and the magnetic coil measurement system

Inventive Principle:
Principle #24Intermediary (Mediator)

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 effectively reduces the impact of electrically conductive foreign and interfering objects on measurement results, allowing for more accurate detection of conductive objects in the substrate by weakening the resulting magnetic field and using a difference signal to eliminate interference effects.

Implementation Method 1

Current pulses are periodically sent through several transmitter coils so that the transmitter coils build up a magnetic field

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

Electrical currents (eddy currents) are induced by induction in electrically conductive materials located in the magnetic field

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 3

The secondary magnetic field generates measurement signals in the receiving coils of the magnetic coil device

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3607360B1Device and method for detecting electrically conductive measurement objects in an underground
Publication Date: 2022.08.17 HILTI AG
  • EP3607360B1 patent drawingFigure 1
  • EP3607360B1 patent drawingFigure 2A
  • EP3607360B1 patent drawingFigure 2B

AI summary

The invention relates to a device (10) for detecting electrically conductive measurement objects in a substrate, the device comprising: a housing (21); a magnetic coil unit (34) which is located in the housing (21) and has an emitter coil unit (38) and a receiver coil unit (39); a control unit (36); and an evaluation unit (37). A metal sheet (35) is provided in the housing (21), wherein the magnetic coil unit (34) is mounted on a lower side (53) of the metal sheet (35) facing the substrate during the measurement operation, and the control unit (36) is mounted on an upper side (54) of the metal sheet (35) facing away from the substrate during the measurement operation.