Composite Susceptor Particles for Self-Regulating Induction Heating

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Solution Overview

Problem

Existing susceptor assemblies for inductively heating aerosol-forming substrates face limitations in heating efficiency and temperature control, leading to potential overheating issues.

Innovation Solution

A susceptor assembly comprising composite susceptor particles with a ferromagnetic or ferrimagnetic core and an electrically conductive shell, which utilize high magnetic permeability to enhance heating efficiency and self-regulate temperature through changes in magnetic properties at the Curie temperature, reducing heat generation in the shell and core.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a susceptor assembly uses a single susceptor material optimized for heating efficiency, then heating efficiency is improved, but temperature control capability deteriorates

Engineering Contradiction:

Improveheating efficiencyVSAvoidtemperature control capability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent employs composite susceptor particles consisting of a ferromagnetic or ferrimagnetic core material surrounded by an electrically conductive shell material. The core material provides high magnetic permeability for efficient heating, while the shell material enables temperature monitoring through its electrical resistance changes at the Curie temperature. This composite structure resolves the contradiction by combining materials with complementary properties to achieve both high heating efficiency and reliable temperature control.

Inventive Principle:

Principle #40Composite materials

2Reliability

If a susceptor assembly uses separate susceptor materials for heating and temperature marking, then temperature control capability is improved, but device complexity increases

Engineering Contradiction:

Improvetemperature control capabilityVSAvoidsusceptor assembly structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the heating function and temperature monitoring function into a single composite susceptor particle. The ferromagnetic core material generates heat through magnetic hysteresis losses, while the electrically conductive shell material simultaneously provides temperature indication through resistance changes. This merging eliminates the need for separate susceptor components, reducing device complexity while maintaining temperature control capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The composite susceptor particle integrates multiple functional materials into a unified structure where the core-shell configuration allows both heating and temperature monitoring functions to coexist within a single component, simplifying the overall susceptor assembly design.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If the particle shell is made thinner to reduce material cost, then manufacturing cost is reduced, but heating efficiency deteriorates

Engineering Contradiction:

Improvemanufacturing costVSAvoidheating efficiency

Core Design Contradiction:

Ease of manufactureVSUse of energy by moving object

Solution Approach 1:

The patent specifies that the shell thickness should be between 1 micrometer and 100 micrometers, optimizing this parameter to balance material cost and heating efficiency. The thin shell reduces material consumption and manufacturing cost while maintaining sufficient electrical conductivity for temperature monitoring and adequate coupling with the magnetic field for efficient heating.

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 composite susceptor particles provide improved heating efficiency and self-regulating temperature control, preventing overheating without active control mechanisms, while reducing material and manufacturing costs.

Implementation Method 1

the substrate may be arranged in thermal proximity or direct physical contact with a susceptor which is capable to generate heat due to at least one of eddy currents or hysteresis losses when it is exposed to an alternating magnetic field

Methodology Applied

Scientific EffectMagnetic hysteresis: Magnetic Hysteresis

Implementation Method 2

Methodology Applied

Scientific EffectEddy currents: Eddy Currents

Implementation Method 3

the second susceptor material is chosen such as to have a Curie temperature corresponding to a predefined operating temperature of the susceptor assembly. At its Curie temperature, the magnetic properties of the second susceptor change from ferromagnetic or ferrimagnetic to paramagnetic

Methodology Applied

Scientific EffectCurie temperature transition: Curie Point (ferromagnetic)

Data Source

PatentUS20250280884A1Susceptor assembly comprising one or more composite susceptor particles

Publication Date: 2025.09.11 PHILIP MORRIS PRODUCTS SA

AI summary

A susceptor assembly for inductively heating an aerosol-forming substrate under an influence of an alternating magnetic field is provided, the susceptor assembly including: one or more composite susceptor particles, each one of the one or more composite susceptor particles including a particle core and a particle shell entirely encapsulating the particle core, the particle core including or being made of a ferromagnetic or ferrimagnetic core material, and the particle shell including or being made of an electrically conductive shell material. An aerosol-generating article including at least one aerosol-forming substrate and the susceptor assembly is also provided. An aerosol-generating system comprising the aerosol-generating article and an inductively heating aerosol-generating device is also provided.