Inductive Heating Susceptor Assembly with Dual Resistance Coefficients
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Solution Overview
Problem
Existing inductively heating aerosol-generating devices face challenges in accurately controlling the temperature of the aerosol-forming substrate due to difficulties in distinguishing between the Curie temperature of the susceptor material and a user's puff, leading to potential overheating.
Innovation Solution
The use of 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, which provides a distinct minimum resistance value at 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 the Curie temperature can be detected, but it becomes difficult to distinguish between Curie temperature reach and user puff events
Solution Approach 1:
The susceptor is divided into two separate materials: a first susceptor material optimized for heating efficiency and a second susceptor material serving as a temperature marker with a specific Curie temperature. This segmentation allows the temperature monitoring function to be separated from the heating function, enabling more reliable temperature detection without interference from user puff events.
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 properties specifically tailored for temperature monitoring at the Curie point. This local differentiation enables simultaneous optimization of heating efficiency and temperature control accuracy.
2Temperature
If controller increases heating power to counteract cool down during user puff, then temperature maintenance is improved, but overheating occurs when Curie temperature detection is erroneous
Solution Approach 1:
By segmenting the susceptor into heating-optimized material and temperature-marker material, the system can accurately detect Curie temperature without false positives from puff-induced resistance changes. This reliable detection prevents erroneous overheating corrections while maintaining proper temperature stability through appropriate heating power adjustment.
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 solution enables precise temperature control of the aerosol-forming substrate, preventing undesired overheating by reliably identifying the Curie temperature of the susceptor material, thus ensuring consistent and safe aerosol generation.
Implementation Method 1
an induction source which is configured to generate an alternating electromagnetic field
Implementation Method 2
induces at least one of heat generating eddy currents or hysteresis losses in the susceptor
Implementation Method 3
induces at least one of heat generating eddy currents or hysteresis losses in the susceptor
Implementation Method 4
susceptor assembly which is configured and arranged to inductively heat the aerosol-forming substrate
Implementation Method 5
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
Implementation Method 6
The first susceptor comprises a first susceptor material having a positive temperature coefficient of resistance
Implementation Method 7
The second susceptor comprises a second ferromagnetic or ferrimagnetic susceptor material having a negative temperature coefficient of resistance
Data Source
AI summary
There is provided an inductively heating aerosol-generating device configured to generate an aerosol by heating an aerosol-forming substrate, the device including a receiving cavity configured to receive the aerosol-forming substrate; an induction source configured to generate an alternating electromagnetic field; and a susceptor assembly configured and arranged to inductively heat the aerosol-forming substrate within the receiving cavity under influence of the alternating magnetic field generated by the induction source, 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 device and an aerosol-generating article for the aerosol-generating device, the article including an aerosol-forming substrate.