Inductive Susceptor Dry-Run Detection in Aerosol Cartridges
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Solution Overview
Problem
Inductively heated aerosol-generating systems face issues with determining when a liquid aerosol-forming substrate is depleted, leading to unsatisfactory aerosol production and user experience, without increasing the number of electrical components.
Innovation Solution
The system determines the presence of liquid aerosol-forming substrate by monitoring the rate of temperature change of the susceptor using control circuitry, based on the electricity supplied to the inductor coil, without the need for additional sensors, by comparing the rate of temperature change with a dry susceptor threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If inductive heating is used to heat the aerosol-forming substrate, then the electrical components are isolated from the aerosol and the cartridge construction is simplified, but the system cannot determine when the liquid reservoir is depleted
Solution Approach 1:
The susceptor uses its own heating process to generate the detection signal. By monitoring its self-heating rate, the system determines substrate supply status without requiring separate sensors or additional electrical connections in the cartridge. The susceptor's thermal behavior itself becomes the detection mechanism.
Solution Approach 2:
The patent replaces mechanical/electrical sensing mechanisms with a thermal field-based detection method. Instead of using electrical sensors or mechanical switches to detect substrate depletion, the system uses thermal monitoring of the susceptor to infer substrate supply status, leveraging the natural thermal properties of the heating element.
2Reliability
If the liquid reservoir is depleted, then the aerosol production becomes unsatisfactory, but the system has no means to detect this condition
Solution Approach 1:
The system implements feedback by continuously monitoring the susceptor's temperature change rate and using this information to detect substrate supply status. The control circuitry receives thermal information from the susceptor and adjusts system operation accordingly, creating a closed-loop detection system that maintains reliable aerosol production.
Solution Approach 2:
The patent detects substrate depletion by monitoring changes in the susceptor's thermal parameters, specifically the rate of temperature change. When the substrate is depleted, the thermal behavior of the susceptor changes detectably, allowing the system to identify the depleted state through parameter monitoring rather than direct measurement.
3Measurement precision
If additional sensors are added to detect substrate supply status, then the detection accuracy improves, but the number of electrical components increases
Solution Approach 1:
The susceptor serves multiple functions: it acts as both the heating element for aerosol generation and the sensor for substrate supply detection. By making the heating element universal, the system eliminates the need for separate detection components, achieving multi-functionality that reduces overall system complexity while maintaining detection capability.
Solution Approach 2:
The susceptor detects its own substrate supply status through its own thermal behavior. The heating element monitors its own temperature change rate to determine whether substrate is being supplied, making the detection system self-contained and eliminating the need for external sensors or additional electrical components.
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
Accurately detects the supply of liquid aerosol-forming substrate, preventing unsatisfactory aerosol production and ensuring optimal system operation, while maintaining a minimal component count.
Implementation Method 1
an inductor coil configured to generate an alternating magnetic field for heating the susceptor
Implementation Method 2
the susceptor is heated by at least one of Joule heating from induced eddy currents in the susceptor and hysteresis losses
Implementation Method 3
The heated susceptor heats the aerosol-forming substrate causing volatile compounds to be released from the aerosol-forming substrate, which cool to form an inhalable aerosol
Data Source
AI summary
An aerosol-generating system is provided, including: a liquid reservoir configured to store a liquid aerosol-forming substrate; a susceptor configured to receive a supply of liquid aerosol-forming substrate from the liquid reservoir and to heat the liquid aerosol-forming substrate to form an aerosol; an inductor coil configured to generate an alternating magnetic field for heating the susceptor; a power supply configured to supply electricity to the inductor coil; and control circuitry configured to determine a parameter indicative of a rate of temperature change of the susceptor, based on the electricity supplied to the inductor coil, and determine whether the susceptor is supplied with the liquid aerosol-forming substrate, based on a comparison between a dry susceptor threshold and the parameter indicative of the rate of temperature change of the susceptor. A method of controlling an aerosol-generating system is also provided.