Inductive Aerosol Article With Thermal Valve and Field Shielding
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Solution Overview
Problem
Aerosol generating systems face limitations in heating rate due to safety concerns regarding the strength of the electromagnetic field, which restricts the intensity of the magnetic field that can be generated, leading to suboptimal heating of tobacco substrates in heated tobacco products.
Innovation Solution
An aerosol generating article with an airflow channel, inductively heatable susceptors, a valve that opens at a transition temperature to allow airflow, and a conductive loop generating a reverse magnetic field to prevent ignition and sustained combustion, utilizing shape memory alloys or metals for the valve and loop to control airflow and heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the magnetic field strength is increased to improve heating rate, then the heating efficiency improves, but user safety deteriorates due to excessive electromagnetic field exposure
Solution Approach 1:
A conductive loop is introduced as an intermediary component between the oscillating magnetic field source and the user. The loop generates a reverse magnetic field that opposes and reduces the net electromagnetic field strength in the user exposure zone, while allowing the heating process to continue effectively
Solution Approach 2:
The conductive loop performs preliminary anti-action by generating a counteracting magnetic field before the user is exposed to excessive electromagnetic radiation. This proactive approach prevents harmful field levels from reaching the user while maintaining heating efficiency
2Ease of operation
If the valve opens early to allow airflow, then user convenience improves, but combustion safety deteriorates due to risk of ignition
Solution Approach 1:
The valve's opening state is controlled by temperature parameter changes. The shape memory alloy material undergoes a phase transition at a specific temperature, causing the valve to automatically open only when the substrate has reached the safe operating temperature, thereby preventing ignition while ensuring user convenience
3Object-affected harmful factors
If the magnetic field strength is limited for safety, then user safety improves, but heating efficiency deteriorates due to insufficient heating rate
Solution Approach 1:
The conductive loop acts as a mediator that allows strong magnetic fields to be used for heating while protecting the user. It selectively attenuates the electromagnetic field in the user direction while maintaining field strength sufficient for effective heating of the substrate
Solution Approach 2:
The electromagnetic field distribution is made non-uniform through the conductive loop, creating different field strengths in different spatial zones: strong field intensity is maintained in the heating zone near the substrate, while weak field intensity is provided in the user exposure zone
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 solution ensures the aerosol is released only when the device reaches the optimal operating temperature, preventing ignition and allowing for efficient heating without exposing users to high electromagnetic fields, thus enhancing the heating rate and safety.
Implementation Method 1
the tobacco substrate is heated by one or more inductively heatable susceptors located inside the article. When the article is placed inside an oscillating magnetic field, the susceptors couple to the magnetic field and produce heat
Implementation Method 2
a conductive loop that is spaced from the material part along the first axis and is configured to produce, when in the presence of an oscillating magnetic field aligned substantially along the first axis, a reverse magnetic field aligned oppositely to the oscillating magnetic field
Implementation Method 3
Shape memory alloys are one class of materials suitable for forming the valve. A shape memory alloy can be plastically deformed into a first form while cool, i.e. when below the transition temperature. When heated to the transition temperature (which is a property of the particular alloy), the shape memory alloy reverts to a second form
Implementation Method 4
In other embodiments, as an alternative to a shape memory alloy, the valve could comprise a metal (for example copper or aluminium) configured such that thermal expansion of the metal causes the valve to open when at the transition temperature
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
An aerosol generating article (201) is described. The article (201) comprises an airflow channel (211) that extends along a first axis. A material part (213) is disposed inside the airflow channel (211), wherein the material part (213) comprises a substrate (205) for generating an aerosol and one or more inductively heatable susceptors (207) for heating the substrate (205). A valve (101) is also disposed inside the airflow channel (211) and spaced from the material part (213) along the first axis, the valve (101) having an open state and a closed state, wherein the valve (101) is configured to substantially impede air flow through the airflow channel (211) when in the closed state. The article (201) further comprises a conductive loop (107) that is spaced from the material part (213) along the first axis and is configured to produce, when in the presence of an oscillating magnetic field aligned substantially along the first axis, a reverse magnetic field aligned oppositely to the oscillating magnetic field.