Compact Inertial Igniter for Munitions with Short Duration Firing Setback
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Solution Overview
Problem
Current inertial igniters for thermal batteries in munitions are large, complex, and not suitable for small or low-power applications, particularly those with short duration firing setback acceleration, requiring a compact and reliable ignition solution that distinguishes between firing and accidental acceleration events while ensuring safety and high reliability.
Innovation Solution
A novel miniature inertial igniter design featuring a lever-type striker release element with a preloaded torsion spring and rotating striker mass, which is rotationally hinged to the igniter body, allowing for efficient ignition of pyrotechnic materials with a compact structure and enhanced safety mechanisms to prevent accidental initiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional inertial igniters are used to ensure reliable ignition under firing acceleration, then ignition reliability is improved, but the device volume and height increase making them unsuitable for small or low-power thermal batteries
Solution Approach 1:
The igniter is divided into functionally independent modules: a striker assembly, a pyrotechnic composition, and a housing with acceleration sensing elements. This segmentation allows each component to be optimized for its specific function while reducing overall volume, enabling reliable ignition in compact configurations for small thermal batteries
Solution Approach 2:
The striker assembly is nested within the housing, and the pyrotechnic composition is contained within the striker assembly. This nested configuration maximizes space utilization and minimizes the overall volume of the igniter while maintaining all necessary functional components for reliable ignition under firing acceleration
2Object-affected harmful factors
If conventional inertial igniters are designed to differentiate between firing and accidental acceleration events, then safety is improved, but the device complexity increases
Solution Approach 1:
The igniter uses acceleration magnitude and duration parameters to differentiate between firing events and accidental drops. By monitoring these parameter thresholds, the system can distinguish legitimate ignition conditions from hazardous events, providing safety without requiring complex mechanical safety mechanisms
Solution Approach 2:
The patent replaces complex mechanical safety systems with an acceleration-based sensing mechanism that uses physical principles to detect and respond to different acceleration profiles. This substitution simplifies the overall device complexity while maintaining effective safety functionality
3Adaptability or versatility
If the igniter height is reduced to fit small thermal batteries, then adaptability is improved, but the ability to provide sufficient striking action for ignition may be compromised
Solution Approach 1:
The striker is pre-positioned and pre-loaded within the compact housing, ready to deliver immediate impact force when activation conditions are met. This preliminary preparation ensures that sufficient striking action is available even in the reduced height configuration, maintaining effective ignition capability while adapting to small thermal battery form factors
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 at specified acceleration levels with a significantly reduced height, ensuring safety and reliability, suitable for small thermal batteries and munitions with short duration firing setback acceleration, while maintaining a long shelf life and cost-effectiveness.
Implementation Method 1
a preloaded torsion spring and rotating striker mass
Implementation Method 2
inertial igniters operate based on the firing acceleration
Implementation Method 3
The striker may be akin to a firing pin and the target akin to a standard percussion cap primer
Data Source
AI summary
An inertial igniter including: a body having a base; a striker release element rotatably disposed on the body, the striker release element having a first surface; a first biasing element for biasing the striker release element away from the base; a striker mass rotatably disposed on the base along a second axis, the striker mass having a second surface corresponding to the first surface of the striker release element, the first surface obstructing rotation of the striker mass; and a second biasing element for biasing the striker mass such that the second surface is biased towards the first surface; wherein when the body experiences an acceleration profile of a predetermined magnitude and duration, the striker release element rotates towards the base to release an engagement between the first and second surfaces and allow the striker mass to rotate under a biasing force of the second biasing element.