Inductive Heating Assembly for Aerosol Substrate Temperature Control
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Solution Overview
Problem
Existing aerosol-generating systems face challenges in accurately controlling the temperature of aerosol-forming substrates due to difficulties in distinguishing between the Curie temperature of the susceptor material and a user's puff, leading to potential overheating.
Innovation Solution
An inductive heating assembly that includes a DC power supply, an induction source, and a susceptor assembly with a first and second susceptor material, where the controller uses the minimum apparent resistance during pre-heating as a temperature marker, allowing for closed-loop offset control to maintain the operating temperature without misinterpreting it as a user's puff.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the electrical current absorbed by the induction source is monitored to detect Curie temperature, then temperature control is achieved, but it becomes difficult to distinguish between Curie temperature detection and user puff detection
Solution Approach 1:
The patent segments the electrical current signal into two distinct components: a DC component representing the average current and an AC component representing fluctuations. By separating and analyzing these components independently, the system can detect Curie temperature through DC component changes while identifying user puffs through AC component patterns, thus resolving the signal differentiation difficulty.
Solution Approach 2:
The patent introduces an intermediary processing stage that analyzes both DC and AC components of the electrical current signal. This intermediary analysis mechanism acts as a mediator between the raw electrical signal and the final temperature control decision, enabling reliable distinction between Curie temperature detection and user puff detection through multi-component signal analysis.
2Temperature
If controller-induced heating power increase is applied to counteract cool down during user puff, then temperature stability is improved, but erroneous identification of Curie temperature as user puff causes undesired overheating
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors both DC and AC components of the electrical current signal. The controller adjusts heating power based on feedback from the DC component (indicating temperature) and AC component (indicating user puff), enabling stable temperature control while preventing erroneous overheating through multi-signal feedback analysis.
Solution Approach 2:
The patent changes the parameter used for temperature control from monitoring only the AC component to monitoring the DC component of the electrical current. This parameter change enables accurate temperature tracking without misinterpreting user puff signals, thus maintaining temperature stability while eliminating overheating risk.
3Extent of automation
If a second susceptor material with Curie temperature is used as temperature marker, then temperature control capability is improved, but the resistance change pattern overlaps with user puff signal
Solution Approach 1:
The patent adds another dimension to the signal analysis by examining both the DC component (average current indicating resistance changes from Curie temperature) and AC component (fluctuations indicating user puff). This dimensional expansion in signal space eliminates interpretation ambiguity while maintaining automatic temperature control capability.
Solution Approach 2:
The patent uses a composite susceptor assembly comprising a first susceptor for heating and a second susceptor with specific Curie temperature for temperature marking. This composite structure enables automated temperature control while the multi-component electrical signal analysis resolves the information loss caused by overlapping resistance change patterns.
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 ensures precise temperature control of the aerosol-forming substrate, preventing overheating by reliably distinguishing the Curie temperature from a user's puff, resulting in stable and accurate heating.
Implementation Method 1
The induction source is configured for generating an alternating electromagnetic field that induces at least one of heat generating eddy currents or hysteresis losses in the susceptor
Implementation Method 2
The induction source is configured for generating an alternating electromagnetic field that induces at least one of heat generating eddy currents or hysteresis losses in the susceptor
Implementation Method 3
The induction source is configured for generating an alternating electromagnetic field that induces at least one of heat generating eddy currents or hysteresis losses in the susceptor
Implementation Method 4
heating assembly and a method for inductively heating an 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
Data Source
AI summary
There is provided an inductive heating assembly to inductively heat an aerosol-forming substrate to an operating temperature, the assembly including an induction source connected to a DC power supply to generate an alternating electromagnetic field to inductively heat a susceptor assembly including a first susceptor and a second susceptor having a Curie temperature below the operating temperature, and a controller operatively connected to the induction source and the DC power supply, to determine an actual apparent resistance of the susceptor assembly indicative of the actual temperature of the susceptor assembly, to determine a minimum value of the apparent resistance occurring during pre-heating of the susceptor assembly, and to control operation of the induction source such that the actual apparent resistance corresponds to the determined minimum value of the apparent resistance plus a pre-determined offset value of the apparent resistance to control heating of the substrate to the operating temperature.