Multi-Stage Inertial Igniter with Nested Locking Elements
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Solution Overview
Problem
Current inertial igniters for thermal batteries are too large and unsuitable for small, low-power applications, particularly in miniaturized fuzing and smart munitions, due to their volume and susceptibility to accidental ignition, and they are not sealed, making them prone to damage from environmental factors.
Innovation Solution
A multi-stage inertial igniter design with a housing and a movable striker supported by first and second stages, featuring common cross-sectional volume locking elements that release upon predetermined accelerations, reducing the overall axial length and volume while enhancing safety and fire/no-fire characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional single-stage inertial igniters are used, then the igniter can provide sufficient delay mechanism, but the axial length and volume become too large for miniaturized applications
Solution Approach 1:
The igniter is divided into multiple stages (first stage, second stage, third stage) with each stage containing locking elements and delay mechanisms. This segmentation allows the total delay stroke to be distributed across multiple smaller components arranged in series, reducing the axial length and volume while maintaining the required safety delay characteristics.
Solution Approach 2:
The locking elements of different stages are positioned to occupy common cross-sectional volumes along the longitudinal axis. The first stage locking elements, second stage locking elements, and third stage locking elements are nested within the same cylindrical envelope, allowing compact arrangement and minimizing the overall igniter volume.
2Volume of moving object
If the igniter is miniaturized to fit small thermal batteries, then the volume is reduced, but the susceptibility to accidental ignition increases
Solution Approach 1:
Multiple locking elements are engaged in advance before firing. The first stage locking elements, second stage locking elements, and third stage locking elements all must be simultaneously engaged for the igniter to function. This preliminary engagement of multiple safety mechanisms reduces the probability of accidental ignition while maintaining compact dimensions.
Solution Approach 2:
The multi-stage design with distributed locking elements provides redundant safety protection. Each stage acts as a cushion against accidental activation, requiring multiple independent events to occur simultaneously to trigger ignition, thereby protecting against harmful accidental ignition in miniaturized applications.
3Reliability
If the igniter components are distributed across larger volume, then safety delay is improved, but the axial length increases making it unsuitable for miniaturized fuzing
Solution Approach 1:
Instead of distributing locking elements along the axial direction, the invention distributes them in the radial dimension by having multiple stages occupy common cross-sectional volumes. The locking elements are arranged concentrically or in overlapping radial positions, maintaining short axial length while providing extended safety delay through multiple stages.
Solution Approach 2:
The locking elements of different stages are nested within common cross-sectional volumes, with each stage's locking mechanism positioned within the same cylindrical envelope. This nesting allows the safety delay to be extended through multiple stages without increasing the axial length, making the igniter suitable for miniaturized fuzing applications.
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 multi-stage design reduces the axial length and volume of the igniter, making it suitable for small thermal batteries and improving safety by distributing the delay stroke across multiple stages, thereby preventing accidental ignition and maintaining igniter integrity.
Implementation Method 1
a movable striker supported by first and second stages, the first stage having a first locking element for releasing the second stage upon a first predetermined acceleration of the housing and the second stage having a second locking element for releasing the striker upon a second predetermined acceleration of the housing greater than the first predetermined acceleration
Data Source
AI summary
An inertia igniter including: a housing; and a movable striker supported by first and second stages, the first stage having a first locking element for releasing the second stage upon a first predetermined acceleration of the housing and the second stage having a second locking element for releasing the striker upon a second predetermined acceleration of the housing greater than the first predetermined acceleration. Wherein the first and second locking elements of the first and second stages occupy a common cross-sectional volume along a longitudinal axis of the housing.