Inductive Heater Sensor Layout for Magnetic Noise Cancellation
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Solution Overview
Problem
Determining the temperature of a susceptor in an inductive heater assembly for an aerosol-generating device is challenging due to the high level of noise introduced by the varying magnetic field, making it difficult to accurately measure and control the heating process.
Innovation Solution
An inductive heater assembly with a temperature sensor comprising a first and second resistive sensing element positioned to oppose the magnetic field induced currents, reducing noise and improving temperature measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is used to measure the temperature of the susceptor in an inductive heater assembly, then temperature control capability is improved, but the varying magnetic field introduces high levels of noise into the sensor signal making the measurement inaccurate or unusable
Solution Approach 1:
The patent applies the principle of converting harm into benefit by using the varying magnetic field that normally causes noise to instead induce opposing currents in the sensing elements. The first and second resistive sensing elements are positioned and oriented such that the varying magnetic field induces currents that oppose each other, causing the magnetic field interference to cancel out. This transforms the harmful magnetic field noise into a beneficial self-cancelling effect, allowing accurate temperature measurement in the presence of the inductive heating magnetic field.
2Productivity
If the susceptor is heated using an inductive heater with an inductor coil, then heating efficiency is improved, but determining the temperature becomes challenging due to noise from the varying magnetic field
Solution Approach 1:
The patent resolves this contradiction by designing a temperature sensor where the first and second resistive sensing elements are positioned relative to each other such that currents induced by the varying magnetic field oppose one another. This configuration converts the harmful magnetic field interference into a self-cancelling effect, enabling accurate temperature detection while maintaining efficient inductive heating.
Solution Approach 2:
The patent introduces a intermediary structure - the dual sensing element configuration with opposing current paths - that mediates between the varying magnetic field and the temperature measurement function. This intermediary arrangement allows the sensor to operate in the magnetic field environment without being adversely affected, bridging the gap between efficient inductive heating and accurate temperature measurement.
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 temperature sensor arrangement effectively cancels out magnetic field noise, allowing for precise temperature determination and control of the susceptor, enhancing the heating process accuracy.
Implementation Method 1
The inductor generates a varying magnetic field to generate eddy currents and hysteresis losses in the susceptor element, causing the susceptor element to heat up
Implementation Method 2
The inductor generates a varying magnetic field to generate eddy currents and hysteresis losses in the susceptor element, causing the susceptor element to heat up
Implementation Method 3
The inductor generates a varying magnetic field to generate eddy currents and hysteresis losses in the susceptor element
Implementation Method 4
the resistance of the resistive heating element can be measured and the temperature determined based on a known relationship between temperature and resistance
Implementation Method 5
The first resistive sensing element is positioned relative to the second resistive sensing element such that a current induced in the first resistive sensing element by the varying magnetic field opposes a current induced in the second resistive sensing element by the varying magnetic field
Data Source
AI summary
An inductive heater assembly for an aerosol-generating device is provided, the assembly including: at least one inductor coil configured to generate a varying magnetic field when a varying electric current flows through the coil; at least one susceptor arranged to be penetrated by the magnetic field generated by the coil to heat the susceptor; at least one temperature sensor arranged to determine a temperature of the susceptor, the temperature sensor includes first and second resistive sensing elements, the first element being connected to the second element, and the first element being positioned relative to the second element such that a current induced in the first element by the magnetic field opposes a current induced in the second element by the magnetic field. An aerosol-generating device including the inductive heater assembly, control circuitry, and a power source, is also provided.