Multistage Thermal Trigger Device for Munitions Safety
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Solution Overview
Problem
Current thermal triggers lack a multistage activation mechanism to safely manage extreme temperature conditions, particularly in environments like solid rocket motors and munitions, where rapid temperature changes can lead to unintended initiation of propellants or explosives, posing hazards to personnel and equipment.
Innovation Solution
A multistage thermal trigger device with a first stage that activates at a lower temperature to arm an arming assembly, and a second stage with an autoignition material capsule that activates at a higher temperature to initiate an output assembly, ensuring safe venting or deflagration in extreme heat scenarios, preventing over-pressurization and detonation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-stage thermal trigger is used, then the device complexity is low, but the reliability is insufficient for managing extreme temperature conditions
Solution Approach 1:
The thermal trigger is divided into two independent stages: a first stage with a first thermal actuator that activates at a first temperature, and a second stage with a second thermal actuator that activates at a second temperature. This segmentation allows each stage to be optimized for its specific temperature threshold, improving overall reliability in extreme temperature conditions while maintaining manageable complexity through modular design.
Solution Approach 2:
The first stage thermal actuator performs preliminary action by activating at a lower temperature to prepare the system before the second stage activates at a higher temperature. This preliminary action creates a staged response that enhances safety by providing intermediate protection measures before catastrophic failure occurs, thereby improving reliability without requiring complete system redesign.
2Reliability
If a multistage activation mechanism is implemented, then the reliability and safety are improved, but the device complexity increases
Solution Approach 1:
The thermal trigger system is segmented into distinct functional modules: first stage thermal actuator, second stage thermal actuator, and output device. Each module operates independently at its designated temperature threshold, allowing for simplified individual component design that collectively achieves high reliability in multistage protection.
Solution Approach 2:
The system utilizes parameter changes by designing thermal actuators with different activation temperatures. The first thermal actuator is calibrated to activate at a first temperature threshold, while the second thermal actuator activates at a second temperature threshold. This parameter differentiation enables the multistage mechanism to provide progressive protection, improving reliability while keeping each individual actuator design relatively simple.
3Reliability
If thermal triggers are used in solid rocket motors, then the productivity and safety are enhanced, but the risk of unintended initiation increases
Solution Approach 1:
The first stage thermal actuator performs preliminary protective action by activating at a lower temperature threshold before the propellants or explosives reach dangerous temperature levels. This preliminary intervention can trigger safety mechanisms or venting systems that prevent the temperature from rising to the point of unintended initiation, thereby enhancing safety while reducing risk.
Solution Approach 2:
The multistage thermal trigger system acts as an intermediary between the thermal environment and the propellants/explosives. The two-stage mechanism provides buffered protection, where the first stage intercepts lower-level thermal threats and the second stage handles higher-level threats, preventing direct exposure of the propellants to extreme temperatures that could cause unintended initiation.
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 multistage thermal trigger device effectively responds to slow and fast cook-off environments, initiating safe venting systems or linear shaped charges to prevent catastrophic failures in solid rocket motors and munitions, enhancing safety by delaying arming and maximizing response time for firefighters.
Implementation Method 1
a first thermal actuator that activates at a first temperature. The first thermal actuator may be coupled with an arming assembly having a disarmed position and an armed position. The first stage may reposition the arming assembly from a disarmed position to an armed position in response to activation of the first thermal actuator.
Implementation Method 2
a second thermal actuator that activates at a second temperature, wherein the second temperature is higher than the first temperature. When the second thermal actuator is activated, it may in turn activate an output assembly via the arming assembly.
Implementation Method 3
an autoignition material disposed inside the hermetically or environmentally sealed capsule; a gas permeable retainer system which retains the autoignition material in position
Data Source
AI summary
Multistage thermal trigger devices disclosed herein may include a first stage and a second stage, wherein the first stage activates at a first temperature, and wherein the second stage activates at a second temperature. The first stage activates an arming assembly so that the second stage is armed. The second stage may then activate the output of the multistage thermal trigger device, via the arming assembly, when the second temperature is reached. An autoignition material (AIM) capsule is also disclosed herein. The AIM capsule may be deployed in connection with the disclosed multistage thermal trigger devices.