Compact Inertial Igniter for Munitions with Adjustable Thresholds
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Solution Overview
Problem
Current inertial igniters for thermal batteries in munitions are large, complex, and costly, making them unsuitable for small thermal batteries and applications with low firing setback acceleration or short duration, and they lack mechanisms for independently adjusting safety acceleration thresholds and time delays, which affects reliability and safety.
Innovation Solution
A compact inertial igniter design with a movable impact mass and a release mechanism that adjusts based on acceleration thresholds, minimizing friction and stiction, allowing for independent adjustment of safety and all-fire acceleration profiles, and incorporating a biasing member to ensure reliable ignition with minimal parts and reduced manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional inertial igniters are used in small thermal batteries, then the batteries can be activated, but the igniters are too large and complex for small battery applications
Solution Approach 1:
The igniter is divided into separate functional components: a striker assembly, a pyrotechnic charge, and a housing with separate acceleration threshold adjustment mechanisms. This segmentation allows each component to be optimized independently for small battery applications while maintaining reliable ignition function.
Solution Approach 2:
The igniter incorporates adjustable acceleration thresholds and variable time delays that can be dynamically configured based on specific application requirements. This dynamic adjustability allows the same compact igniter design to reliably adapt to different battery sizes and firing conditions.
2Adaptability or versatility
If inertial igniters are designed for low firing setback acceleration, then they can be used in more applications, but they become more difficult to distinguish between accidental drops and firing events
Solution Approach 1:
The igniter incorporates independently adjustable acceleration threshold parameters and time delay parameters that can be configured to distinguish between accidental drops and legitimate firing events. By adjusting these parameters, the igniter can be adapted to different application ranges while maintaining reliable safety discrimination.
3Reliability
If complex safety mechanisms are added to distinguish accidental drops from firing events, then safety is improved, but device complexity increases
Solution Approach 1:
The safety mechanism is merged with the primary ignition mechanism into a single integrated assembly. The acceleration threshold detection and time delay functions are combined with the striker release mechanism, eliminating the need for separate complex safety systems while maintaining reliable safety discrimination.
4Ease of manufacture
If traditional inertial igniter designs are used, then ignition function is provided, but manufacturing costs are high and manufacturing complexity is increased
Solution Approach 1:
The igniter design incorporates universal components and standardized assembly procedures that can be manufactured using conventional processes. The adjustable thresholds and time delays are achieved through simple mechanical configurations rather than complex electronic systems, reducing manufacturing complexity and cost.
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 design enables reliable ignition in small thermal batteries with low firing setback acceleration and short duration, reduces the range of acceleration for initiation certainty, and lowers manufacturing costs, ensuring high reliability and safety by minimizing accidental ignitions.
Implementation Method 1
a release mechanism configured to be movable between a restrained position for preventing movement of the impact mass and a released position for permitting movement of the impact mass when the release mechanism is subjected to an acceleration greater than a predetermined magnitude and duration; wherein the release mechanism having a release mass movable when subjected to the acceleration
Implementation Method 2
incorporating a biasing member to ensure reliable ignition with minimal parts and reduced manufacturing complexity
Data Source
AI summary
A device including: an impact mass movably restrained relative to a base; and a release mechanism configured to be movable between a restrained position for preventing movement of the impact mass and a released position for permitting movement of the impact mass when the release mechanism is subjected to an acceleration greater than a predetermined magnitude and duration; wherein the release mechanism having a release mass movable when subjected to the acceleration, the movement of the release mass not being influenced by movement of the impact mass.