Piezoelectric Igniter for Munitions with LC Resonant Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current igniters for thermal batteries in munitions are either large and unsuitable for small applications or require external power sources and circuitry, lacking programmable delay capabilities and safety features to differentiate between intended firing and accidental acceleration events.
Innovation Solution
Development of miniature electrically initiated inertial igniters that use piezoelectric materials to generate electrical power from firing acceleration, eliminating the need for external power sources and incorporating programmable logic for safe and delayed initiation of pyrotechnic materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional igniters are used for thermal batteries, then reliable ignition is achieved, but the device size becomes large and external power sources are required
Solution Approach 1:
The patent combines the power generation function and ignition function into a single integrated piezoelectric igniter device. The piezoelectric element generates electrical energy from mechanical impact, which directly powers the pyrotechnic ignition, eliminating the need for separate power sources and reducing overall device volume.
Solution Approach 2:
The piezoelectric igniter is self-powered through the impact mechanism itself. The mechanical energy from the impact that would otherwise be wasted is converted by the piezoelectric element into electrical energy to trigger the pyrotechnic charge, making the device self-sufficient without external power requirements.
2Volume of moving object
If externally powered electrical igniters are used, then smaller size is achieved, but external power sources and decision circuitry are required
Solution Approach 1:
The patent extracts and eliminates the external power source and complex decision circuitry from the system. The piezoelectric element directly converts impact energy to electrical energy, removing the need for batteries, power management circuits, and complex control logic while maintaining compact size.
Solution Approach 2:
The patent replaces complex electrical control systems with a direct mechanical-to-electrical conversion mechanism. The piezoelectric element provides a simple, direct path from mechanical impact to electrical ignition signal, eliminating the need for complex electronic decision-making circuitry.
3Use of energy by moving object
If inertial igniters are used, then no external power is needed, but they cannot differentiate between firing acceleration and accidental impact
Solution Approach 1:
The piezoelectric igniter incorporates threshold-based feedback control. The electrical energy generated by the piezoelectric element must exceed a predetermined threshold to activate the pyrotechnic charge, allowing the system to distinguish between sufficient firing impacts and insufficient accidental impacts, thereby providing safety discrimination.
Solution Approach 2:
The patent changes the activation parameter from simple acceleration detection to electrical energy threshold detection. By measuring the electrical energy output of the piezoelectric element rather than directly detecting acceleration, the system can set energy thresholds that reliably differentiate between intentional firing and accidental impacts.
4Power
If thermal batteries are activated immediately, then power is available for munitions flight, but shelf life is reduced due to electrolyte degradation
Solution Approach 1:
The piezoelectric igniter enables preliminary preparation of the thermal battery system during manufacturing and storage. The battery can be pre-assembled with all components in place, remaining inert during shelf storage, and then activated only when needed through impact-triggered pyrotechnic initiation, thereby extending shelf life while ensuring power availability.
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 solution provides a compact, reliable, and safe ignition system for thermal batteries in small munitions, enabling programmable initiation and differentiation between intended firing and accidental events, with the ability to withstand high-G accelerations and maintain functionality over extended shelf life.
Implementation Method 1
An electrical energy generating element, such as a piezoelectric element, is provided to generate an electrical charge in response to an acceleration
Implementation Method 2
The electrical charge is used to initiate a pyrotechnic material to provide a controlled pyrotechnic reaction
Data Source
AI summary
An electrical energy harvesting device for harvesting electrical energy from a pulsed impact loading event. The device including: a piezoelectric element configured to be loaded and unloaded to a first load level by the pulsed impact loading event; and a first inductor coupled to the piezoelectric element configured to be loaded and unloaded to a second load level by the pulsed impact loading event, wherein the piezoelectric element and the first inductor together operate as a first inductor/capacitor (LC) resonant circuit having a first resonance frequency and wherein the loading of the first inductor lags in time the loading of the piezoelectric element.