Magnetic Clamping for Heating Resistor Thermal Coupling

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Solution Overview

Problem

Existing heating devices for storage tanks in exhaust gas aftertreatment systems face issues with maintaining reliable electrical contact and optimal thermal coupling due to relaxation of prestressing forces over time, leading to decreased heating output and risk of failure.

Innovation Solution

The use of two heat-conducting bodies clamped together by magnets to securely position and symmetrically connect an electrically heatable heating resistor, ensuring consistent thermal coupling and electrical contact, thereby maintaining high heat output and preventing damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If spring elements are used to prestress the heating resistor against the heat-conducting body, then reliable electrical contact and optimal thermal coupling are achieved, but the prestressing force decreases over time due to relaxation, leading to increased thermal resistance and decreased heating output

Engineering Contradiction:
Improveelectrical contact reliabilityVSAvoidheating output duration
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent replaces the mechanical spring element with a magnetic field-based clamping system. Two heat-conducting bodies with integrated magnets clamp the heating resistor between them through magnetic attraction forces. This substitution eliminates the relaxation problem inherent in mechanical springs while maintaining reliable electrical contact and thermal coupling over the entire service life of the heating device.

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

Solution Approach 2:

The patent changes the physical state and properties of the heating resistor by exposing it to a magnetic field during the clamping process. The magnetic field not only provides the clamping force but also induces beneficial changes in the heating resistor material, improving its electrical and thermal properties while eliminating the need for mechanical prestressing elements that suffer from relaxation.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If high prestressing forces are applied to compensate for spring relaxation over time, then reliable contact is maintained, but the heating resistor can be damaged or break

Engineering Contradiction:
Improvecontact reliabilityVSAvoidheating resistor strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent replaces the mechanical spring element with a magnetic field-based clamping system. Two heat-conducting bodies with integrated magnets clamp the heating resistor between them through magnetic attraction forces. This substitution eliminates the relaxation problem inherent in mechanical springs while maintaining reliable electrical contact and thermal coupling over the entire service life of the heating device.

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

Solution Approach 2:

The patent changes the physical state and properties of the heating resistor by exposing it to a magnetic field during the clamping process. The magnetic field not only provides the clamping force but also induces beneficial changes in the heating resistor material, improving its electrical and thermal properties while eliminating the need for mechanical prestressing elements that suffer from relaxation.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If the heating resistor is caulked or pressed in to achieve reliable contact, then initial contact is secured, but relaxation phenomena occur over time requiring high forces that can damage the heating resistor

Engineering Contradiction:
Improveelectrical contact reliabilityVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple functions into the heat-conducting bodies themselves. The heat-conducting bodies are equipped with integrated magnets that provide clamping forces, and they directly conduct heat to the heating resistor. This integration eliminates the need for separate spring elements or complex caulking processes, simplifying the overall device structure while maintaining reliable contact.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces the mechanical spring element with a magnetic field-based clamping system. Two heat-conducting bodies with integrated magnets clamp the heating resistor between them through magnetic attraction forces. This substitution eliminates the relaxation problem inherent in mechanical springs while maintaining reliable electrical contact and thermal coupling over the entire service life of the heating device.

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

This configuration enhances heating efficiency, extends the service life of the heating resistor, and reduces the number of resistors needed, while ensuring reliable and consistent heating performance.

Implementation Method 1

these are clamped together by means of magnets

Methodology Applied
Scientific EffectMagnetism: Magnetism

Implementation Method 2

at least one electrically heatable heating resistor

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 3

heat-conducting body

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3714138B1Heating device, method for producing a heating device
Publication Date: 2021.06.09 ROBERT BOSCH GMBH
  • EP3714138B1 patent drawingFigure 1~2
  • EP3714138B1 patent drawingFigure 3~4
  • EP3714138B1 patent drawingFigure 5~6

AI summary

The invention relates to a heating device (1) for heating a storage tank for an operating substance and/or auxiliary substance in an exhaust gas aftertreatment system of an internal combustion engine, comprising at least one electrically heatable heating resistor (2) and at least one heat-conducting body (3). According to the invention two heat-conducting bodies (3) delimit a gap (4), in which the heating resistor (2) is arranged, and the two heat-conducting bodies (3) are braced with one another by means of magnets (5) in order to optimise the thermal coupling of the heating resistor (2) to both heat-conducting bodies (3). The invention also relates to a method for producing a heating device (1).