Ceramic-Cast Heating Cartridge for Deformation-Free Assembly

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Solution Overview

Problem

Existing heating cartridges for spray nozzles require complex processes like plastic deformation of the metal sleeve to achieve high heating outputs, which can damage internal components and are not suitable for all metal sleeve shapes, materials, or coatings.

Innovation Solution

A heating cartridge design that fills the metal sleeve with ceramic casting compound, eliminating the need for plastic deformation and allowing for easy winding of the heating coil around a ceramic core, with a ceramic potting compound forming a core that surrounds the heating coil and fills the space between the core and sleeve, enabling direct temperature sensing and improved thermal coupling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If plastic deformation of the metal sleeve is used to compact ceramic powder, then good thermal coupling between heating coil and metal sleeve is achieved, but the process becomes very complex and requires subsequent grinding of the metal sleeve exterior

Engineering Contradiction:
Improvethermal couplingVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical compaction process (plastic deformation of metal sleeve) with a chemical bonding process (ceramic casting compound that bonds to both heating coil and metal sleeve). The casting compound is poured into the metal sleeve and bonds to the heating coil without requiring mechanical deformation or subsequent grinding operations.

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

Solution Approach 2:

The patent changes the physical state of the bonding material from compacted powder to liquid casting compound. The liquid casting compound flows to fill all gaps and bonds upon setting, eliminating the need for mechanical compaction and subsequent reworking of the metal sleeve exterior.

Inventive Principle:
Principle #35Parameter changes

2Power

If plastic deformation of the metal sleeve is performed to achieve high heating output, then thermal coupling is improved, but components inside the heating cartridge are at risk of damage

Engineering Contradiction:
Improveheating outputVSAvoidcomponent integrity
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The patent replaces the mechanical compaction process with a chemical bonding process using liquid casting compound. This eliminates mechanical stresses that could damage the heating coil, temperature sensor, or other internal components while still achieving excellent thermal coupling for high heating output.

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

Solution Approach 2:

The liquid casting compound acts as a cushioning medium that protects internal components from mechanical damage during assembly. The compound flows around components, providing protective support before final bonding occurs, preventing damage that would occur during mechanical compaction.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Adaptability or versatility

If the metal sleeve is not suitable for plastic deformation (due to shape, material, thickness, or coating), then the heating cartridge cannot be manufactured using conventional methods, but the invention provides a universal solution

Engineering Contradiction:
Improvemetal sleeve compatibilityVSAvoidmanufacturing applicability
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent creates a universal manufacturing method that works with any metal sleeve configuration (different shapes, materials, thicknesses, or coatings). The liquid casting compound can be poured into any metal sleeve and will bond to the heating coil regardless of the sleeve's properties, making the process universally applicable.

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

Solution Approach 2:

By replacing mechanical compaction with liquid casting, the invention removes the constraint that the metal sleeve must be deformable. The liquid casting process adapts to any sleeve geometry or material properties, providing universal manufacturability across different sleeve configurations.

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

4Measurement precision

If a temperature sensor is placed in the ceramic core, then precise temperature measurement is achieved, but mechanical pressure during compaction could damage the sensor

Engineering Contradiction:
Improvetemperature measurement precisionVSAvoidsensor protection
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent replaces mechanical compaction with liquid casting, eliminating mechanical pressure on the temperature sensor. The liquid casting compound flows around the sensor without exerting damaging forces, while still providing thermal coupling for precise temperature measurement at the heating coil.

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

Solution Approach 2:

The liquid casting compound provides protective cushioning around the temperature sensor before bonding occurs. This prevents mechanical damage to the sensor while allowing it to be positioned in the ceramic core for optimal temperature measurement, eliminating the need for protective housings.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 reduces manufacturing complexity, minimizes component damage, and enhances thermal coupling and temperature measurement precision while allowing the cartridge to withstand high pressures, making it suitable for various metal sleeve configurations.

Implementation Method 1

Since the ceramic casting compound is poured into the metal sleeve as a liquid, subsequent compaction through plastic deformation of the metal sleeve is eliminated

Methodology Applied
Scientific EffectFluidity:

Implementation Method 2

a heating coil, wound on a ceramic winding body, is embedded in ceramic powder

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP3993562B1Heating cartridge with ceramic casting compound
Publication Date: 2025.08.27 FRITZ EICHENAUER GMBH & CO KG
  • EP3993562B1 patent drawingFigure 1
  • EP3993562B1 patent drawingFigure 2
  • EP3993562B1 patent drawingFigure 3

AI summary

A heating cartridge is described comprising a ceramic core (11), a heating wire which surrounds the ceramic core (11) as a heating coil (12), and a metal sleeve (13) in which the ceramic core (11) and the heating coil (12) are arranged, wherein the heating coil (12) is embedded in a ceramic potting compound which fills a space between the ceramic core (11) and the inside of the metal sleeve (13).