Annular Inductor Radial Passage for Temperature Monitoring

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Solution Overview

Problem

Conventional inductors used for inductive heat treatment of components result in inhomogeneous temperature distributions, leading to varying structural strengths within the microstructure of the treated components.

Innovation Solution

An inductor design featuring an approximately annular coil with a radial passage that allows electromagnetic radiation to pass from the inside to the outside, enabling the measurement of heat radiation and providing access to the process zone for temperature monitoring and control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a conventional inductor is used for inductive heat treatment, then the heating process can be performed, but the temperature distribution becomes inhomogeneous leading to varying structural strengths

Engineering Contradiction:
Improvetemperature distribution uniformityVSAvoidstructural strength uniformity
Core Design Contradiction:
TemperatureVSManufacturing precision

Solution Approach 1:

The inductor coil is segmented into multiple independent heating zones along its length. Each zone can be controlled separately to compensate for the natural temperature gradients, allowing homogeneous temperature distribution across the entire component surface while maintaining uniform structural strength.

Inventive Principle:
Principle #1Segmentation

2Area of stationary object

If the inductor coil is made compact, then the device size is reduced, but access to the process zone for temperature monitoring becomes impossible

Engineering Contradiction:
Improveinductor sizeVSAvoidprocess zone accessibility
Core Design Contradiction:
Area of stationary objectVSDifficulty of detecting and measuring

Solution Approach 1:

A radiation window or transparent barrier is introduced as an intermediary between the compact inductor coil and the external measurement system. This allows thermal radiation from the process zone to pass through to external sensors while maintaining the compact configuration and protecting the internal heating zone.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If the inductor is designed with a passage for radiation measurement, then temperature monitoring becomes possible, but the coil structure becomes more complex

Engineering Contradiction:
Improvetemperature measurement capabilityVSAvoidcoil structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The passage structure serves multiple functions: it allows thermal radiation to pass through for temperature measurement while also acting as a structural support element and potentially serving as a cooling channel. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in overall device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

This design achieves more homogeneous temperature distributions, allowing for the production of components with uniformly enhanced structural strengths, and enables real-time monitoring and adjustment of the heat treatment process.

Implementation Method 1

Such an inductor generates eddy currents via a magnetic field in the component or workpiece, which lead to an increase in the temperature in the component

Methodology Applied
Scientific EffectEddy currents: Eddy Currents

Implementation Method 2

Such an inductor generates eddy currents via a magnetic field in the component or workpiece

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 3

generates eddy currents via a magnetic field in the component or workpiece, which lead to an increase in the temperature in the component

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 4

allowing electromagnetic radiation to pass from the inside to the outside via the passage and be measured. This makes it possible to measure heat radiation, which escapes from a component held in the interior of the ring-shaped induction coil

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 5

a pyrometer is arranged relative to the passage such that a lens of the pyrometer faces the exit opening of the passage. The thermal radiation emerging through the passage can then enter the lens of the pyrometer and be imaged onto the pyrometer sensor for detection

Methodology Applied
Scientific EffectThermal radiation detection: Thermal Radiation

Data Source

PatentEP3881649B1Inductor and apparatus for inductively heating components and method therefor
Publication Date: 2025.06.04 ROBERT BOSCH GMBH
  • EP3881649B1 patent drawingFigure 1A~1B
  • EP3881649B1 patent drawingFigure 2~3
  • EP3881649B1 patent drawingFigure 4

AI summary

An inductor (10) serves for inductively heating metal components and has an induction coil (10'), wherein the induction coil (10'), which is of approximately annular design, has a passage (13) which passes through the induction coil (10') from its inner circumferential surface (12) to its outer circumferential surface (11) as a cutout in order to allow electromagnetic radiation (17) to pass from the inside to the outside via the passage (13) and to be able to be detected by measurement. In this case, the passage (13) extends in an approximately radial direction. In the apparatus (100) which comprises an inductor of this kind, provision is made for a pyrometer (16) to be arranged in relation to the passage (13) in such a way that a lens (16') of the pyrometer (16) faces the outlet opening (13') of the passage (13) and, by way of its optical axis, is oriented coaxially in relation to the direction of longitudinal extent of the passage (13). The radiation (17) which is detected by the pyrometer (16) across the passage (13) and the temperature ascertained therefrom provides information about the development of process heat as a measurement variable.