Eutectic Thermal Ignition for Aerosol Fire Extinguishers
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Solution Overview
Problem
Existing fire extinguishing aerosol devices face issues with igniter placement requiring high container temperatures for ignition, electrical connection reliability, and risk of fuse damage during shipment, leading to potential malfunctions and safety concerns.
Innovation Solution
A thermal ignition unit with a spring-loaded piston held by a eutectic material that deforms at a predetermined temperature, releasing the piston to strike a primer and ignite the pyrotechnic, allowing for mechanical or heat-activated ignition, and a modular design with a restraining clip for easy assembly and use with various canister sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the igniter is positioned inside the housing to be ignited by high temperature, then the ignition can be achieved, but the container itself must reach high temperature which causes safety issues and requires high activation temperature
Solution Approach 1:
A thermal response element is introduced as an intermediary between the heat source and the pyrotechnic charge. This element responds to temperature changes by mechanically releasing the igniter, allowing ignition at lower container temperatures without direct heating of the igniter itself.
Solution Approach 2:
The patent replaces direct thermal ignition of the igniter with a mechanical release system activated by temperature. The thermal response element converts thermal energy into mechanical motion, which then triggers the igniter, separating the heating function from the ignition function.
2Reliability
If electrical ignition units are used, then ignition can be achieved, but connection to detection devices and releasing panels is required which increases cost and maintenance requirements
Solution Approach 1:
The electrical ignition system is extracted and replaced with a purely mechanical/thermal ignition system. The igniter is no longer electrically operated but is mechanically released by thermal expansion of a response element, eliminating the need for electrical connections to detection devices and releasing panels.
Solution Approach 2:
The patent uses a disposable thermal response element that is inexpensive and simple in structure. This single-use component eliminates complex electrical connections and maintenance requirements, as the entire ignition mechanism is designed to be replaced rather than repaired.
3Reliability
If a fuse is used to extend outside the container for ignition, then ignition at desired temperature is achieved, but the fuse is prone to damage and malfunction during shipment and requires high activation temperature
Solution Approach 1:
The ignition system is segmented into separate functional components: a thermal response element that senses temperature, a mechanical release mechanism, and the igniter. This segmentation allows each component to be optimized independently and prevents damage during shipment, as none of the components require high activation temperatures or external connections.
Solution Approach 2:
The patent changes the activation parameter from high temperature (required by traditional fuses) to a lower temperature threshold that can be safely exceeded during normal use but not during shipment. The thermal response element is designed to remain stable at shipping temperatures but activates at the desired fire temperature.
4Reliability
If a bulb is used to hold a spring loaded pin in place that breaks at prespecified temperature, then ignition is achieved, but the bulb breaking may cause unintended activation during handling
Solution Approach 1:
The patent uses a dynamic thermal response element that gradually expands with temperature rather than breaking suddenly. This progressive deformation provides a safer transition state during handling, allowing the system to withstand normal handling stresses while still activating reliably at the desired temperature through complete thermal expansion.
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 reliable and safe ignition of fire extinguishing aerosols without the need for high container temperatures, reduces electrical connection issues, and allows for easy assembly and use with different canister sizes, enhancing the safety and effectiveness of fire extinguishing devices.
Implementation Method 1
a formed eutectic, which deforms at a predetermined temperature. When such temperature is reached, the piston is released
Implementation Method 2
the piston strikes a primer, which ignites an ignition mix, which further ignites the pyrotechnic
Data Source
AI summary
A fire extinguishing assembly includes an ignition unit and an aerosol generating unit. The ignition unit in one embodiment comprises a spring loaded piston that is held under spring tension by a formed eutectic, which deforms at a predetermined temperature. When such temperature is reached, the piston is released, and strikes a primer to ignite a desired pyrotechnic in the aerosol generating unit. In one embodiment, the piston strikes a primer, which ignites an ignition mix, which further ignites the pyrotechnic. The ignition mix may be formed of the same material as the pyrotechnic. The ignition unit may be releasably engaged with the aerosol generating unit that contains the pyrotechnic. In one embodiment, it is formed with threads for mating with threads on the canister.