Inductive Sensor Coil Positioning for High-Temperature Accuracy

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Solution Overview

Problem

Existing inductive sensors face issues with precise coil positioning due to thermal expansion, leading to mechanical strains and inaccuracies, and require harmful casting materials and lengthy curing processes.

Innovation Solution

The inductive sensor employs a vertical positioning element, such as a spring element, and a lateral positioning element, like a centering pin, to maintain the coil system's position, eliminating the need for adhesives and resins, and using materials with low thermal expansion coefficients.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If standard casting resins and adhesives are used to secure the coil system, then the coil system can be positioned and secured, but the temperature resistance is insufficient and thermal expansion causes mechanical strains and displacements

Engineering Contradiction:
Improvetemperature resistanceVSAvoidcoil system positioning precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the material parameter by using a thermally conductive adhesive instead of standard casting resins or adhesives. This thermally conductive adhesive has superior temperature resistance and thermal conductivity, allowing the coil system to maintain precise positioning while withstanding high operating temperatures without thermal expansion-induced displacement.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite material solution by combining the thermally conductive adhesive with the coil system and housing structure. This composite approach creates a unified assembly that simultaneously provides mechanical bonding and thermal management, resolving the contradiction between positioning precision and temperature resistance.

Inventive Principle:
Principle #40Composite materials

2Temperature

If silicone-based casting materials are used for higher operating temperatures, then temperature resistance is improved, but long waiting times for curing and special casting machines are required

Engineering Contradiction:
Improveoperating temperature resistanceVSAvoidmanufacturing cycle time
Core Design Contradiction:
TemperatureVSProductivity

Solution Approach 1:

The patent replaces the mechanical casting system (vibrating plates, special casting machines) with a simpler adhesive bonding system. The thermally conductive adhesive can be applied using standard adhesive application methods, eliminating the need for specialized casting equipment and significantly reducing manufacturing cycle time while maintaining high temperature resistance.

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

Solution Approach 2:

The patent changes the curing time parameter by using a fast-curing thermally conductive adhesive formulation. This adhesive achieves full strength and thermal conductivity much faster than silicone-based casting materials, eliminating long waiting times and improving manufacturing productivity without sacrificing temperature resistance.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If adhesives and casting materials are used to secure the coil system, then the coil system can be fixed in position, but environmental harm and complicated assembly process result

Engineering Contradiction:
Improvecoil system positioningVSAvoidenvironmental harm
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical composition parameter of the bonding material by selecting a thermally conductive adhesive with environmentally friendly formulation. This adhesive eliminates or reduces harmful substances while maintaining effective bonding strength and thermal conductivity, thus achieving precise coil system positioning without environmental harm.

Inventive Principle:
Principle #35Parameter changes

4Manufacturing precision

If the coil system is secured with rigid bonding materials, then positioning is achieved, but thermal expansion causes mechanical strains and displacement

Engineering Contradiction:
Improvecoil system positioningVSAvoidmechanical stability under thermal stress
Core Design Contradiction:
Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent changes the mechanical property parameters of the bonding material by using a thermally conductive adhesive with appropriate elasticity and thermal expansion characteristics. This adhesive can accommodate thermal expansion and contraction of the coil system and housing, maintaining stable mechanical bonding and precise positioning under thermal stress without causing displacement.

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 design ensures accurate detection of metallic objects at high temperatures by preventing lateral displacement and maintaining contact with the housing, reducing manufacturing time and environmental impact while enhancing sensor reliability and cost-effectiveness.

Implementation Method 1

a vertical positioning element, such as a spring element, that exerts a force on the coil system in the direction of the active surface of the sensor

Methodology Applied
Scientific EffectSpring force: Spring

Implementation Method 2

These sensors operate based on the principle of detecting a change of the impedance or the impulse response of a coil system or a change of the inductive coupling between multiple coil systems when a metallic object is in proximity to the sensor

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4600704A1Inductive sensor
Publication Date: 2025.08.13 PEPPERL & FUCHS SE
  • EP4600704A1 patent drawingFigure 1
  • EP4600704A1 patent drawingFigure 2A~2B
  • EP4600704A1 patent drawingFigure 2C~2D

AI summary

An inductive sensor (1) for detecting metallic objects, comprising: - a sensor housing (4) having a first housing surface (41), which represents the active surface of the sensor (1); - coil system (2) having a front face (21), wherein the front face (21) is positioned rearwardly in front of the first housing surface (41) facing a rearward housing surface (44); - a vertical positioning element (5), wherein the vertical positioning element (5) is configured and arranged to exert a force on the coil system (2) in the direction of, and preferably perpendicular to, the active surface (41) and the rearward housing surface (44), such that the front face (21) of the coil system (2) remains in direct contact with the rearward housing surface (44) of the sensor (1), wherein the vertical positioning element (5) is formed by and/or attached to the sensor housing (4).