Dual Susceptor Assembly for Inductive Aerosol Heating
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Solution Overview
Problem
Existing inductively heatable aerosol-generating systems face challenges in accurately controlling temperature due to similarities in electrical current changes caused by the Curie temperature of the susceptor material and a user's puff, leading to potential overheating.
Innovation Solution
A susceptor assembly comprising a first susceptor with a positive temperature coefficient of resistance and a second susceptor with a negative temperature coefficient of resistance, creating a distinct resistance-over-temperature profile with a minimum value around the Curie temperature of the second susceptor, allowing for reliable temperature control without misinterpretation as a user's puff.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single susceptor material with Curie temperature is used for temperature monitoring, then temperature control is enabled, but electrical current changes during user's puff are misinterpreted as Curie temperature detection leading to overheating
Solution Approach 1:
The susceptor is divided into two distinct materials: a first susceptor material optimized for heating efficiency and a second susceptor material serving as temperature marker. This segmentation allows the temperature monitoring function to be separated from the heating function, enabling more accurate temperature detection without interference from puff-induced current changes.
Solution Approach 2:
Different regions of the susceptor assembly have different material properties tailored to specific functions. The first susceptor material has properties optimized for heat generation and transfer, while the second susceptor material has Curie temperature properties specifically for temperature marking. This local differentiation enables precise temperature control at the target location.
2Temperature
If controller increases heating power to counteract cool down during user's puff, then temperature maintenance is improved, but erroneous Curie temperature detection causes undesired overheating
Solution Approach 1:
The system uses the electrical resistance changes of the second susceptor material at its Curie temperature as feedback signal for temperature control. By monitoring when the resistance changes due to magnetic property transition, the controller can accurately determine when the target temperature is reached and adjust heating power accordingly, preventing both underheating and overheating.
Solution Approach 2:
The system exploits the change in electrical resistance parameter of the second susceptor material at its Curie temperature as a reliable indicator for temperature control. This parameter change is distinct from the resistance changes caused by puff-induced cooling, allowing the controller to differentiate between temperature reach and user activation.
3Productivity
If susceptor assembly uses materials optimized for heating efficiency, then heating performance is improved, but temperature monitoring accuracy deteriorates due to similar electrical current changes from puff cooling
Solution Approach 1:
The susceptor assembly is segmented into two functional materials: the first susceptor material handles heating efficiency with properties optimized for heat generation, while the second susceptor material handles temperature monitoring with Curie temperature properties. This functional segmentation resolves the conflict between heating performance and temperature detection accuracy.
Solution Approach 2:
The susceptor assembly uses a composite structure combining two different susceptor materials with complementary properties. The first material provides efficient heating through its electrical and magnetic properties, while the second material provides accurate temperature marking through its Curie temperature transition. Together they form a composite system that achieves both heating efficiency and precise temperature control.
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 susceptor assembly effectively prevents undesired overheating by using the minimum resistance value as a reliable temperature marker, ensuring accurate heating control of the aerosol-forming substrate.
Implementation Method 1
The first susceptor comprises a first susceptor material having a positive temperature coefficient of resistance
Implementation Method 2
The second susceptor comprises a second ferromagnetic or ferrimagnetic susceptor material having a negative temperature coefficient of resistance
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
Implementation Method 4
The induction source is configured to generate an alternating electromagnetic field that induces at least one of heat generating eddy currents or hysteresis losses in a susceptor
Implementation Method 5
The induction source is configured to generate an alternating electromagnetic field that induces at least one of heat generating eddy currents or hysteresis losses in a susceptor
Implementation Method 6
The induction source is configured to generate an alternating electromagnetic field that induces at least one of heat generating eddy currents or hysteresis losses in a susceptor
Implementation Method 7
aerosol-generating systems—based on inductive heating of an aerosol-forming substrate
Implementation Method 8
The susceptor itself may be integral part of the article and arranged such as to be in thermal proximity or direct physical contact with the substrate to be heated
Data Source
AI summary
There is provided an inductively heatable aerosol-generating article, including an aerosol-forming substrate; and a susceptor assembly configured to inductively heat the aerosol-forming substrate under influence of an alternating magnetic field, the susceptor assembly including a first susceptor and a second susceptor, the first susceptor including a first susceptor material having a positive temperature coefficient of resistance, and the second susceptor including a second ferromagnetic or ferrimagnetic susceptor material having a negative temperature coefficient of resistance. There is also provided an aerosol-generating system including the aerosol-generating article and an aerosol-generating device for the aerosol-generating article.