Miniature Inertial Igniter for Thermal Battery
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Solution Overview
Problem
Current inertial igniters for thermal batteries are too large and unsuitable for small, low-power applications, requiring external power sources and lacking safety mechanisms to prevent accidental ignition, with a need for compact, reliable, and cost-effective designs that can withstand high accelerations and long storage periods.
Innovation Solution
Development of miniature inertial igniters that are scalable, sealed, and integrated directly into thermal batteries, using a nested safety and striker system to ensure reliable ignition only at specified acceleration levels, eliminating the need for intermediate ignition materials and external housings, and utilizing standard percussion cap primers for simplicity and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional inertial igniters are used in thermal batteries, then reliable ignition at high acceleration is achieved, but the igniter volume is too large for small and miniaturized thermal batteries
Solution Approach 1:
The patent applies nesting by placing the striker mechanism inside a compact cylindrical housing that integrates with the thermal battery structure. The safety mechanism is nested within the same housing, allowing both functions to share space. The striker rod, spring, and locking balls are arranged concentrically within the housing, maximizing space utilization and minimizing overall igniter volume while maintaining reliable high-acceleration ignition.
2Object-affected harmful factors
If inertial igniters are designed for low impact levels, then safety against accidental ignition is improved, but the igniter becomes more complex requiring additional safety mechanisms
Solution Approach 1:
The patent implements preliminary anti-action through a safety mechanism that prevents the striker rod from moving unless a specific high-acceleration threshold is exceeded. Locking balls engage with notches in the housing to restrain the striker assembly during normal handling and accidental drops. The spring is pre-compressed but cannot release the striker unless the acceleration force overcomes the locking mechanism, thereby preventing accidental ignition while maintaining simple overall structure.
3Reliability
If electrical igniters are used to provide controlled pyrotechnic reaction, then reliable ignition is achieved, but onboard batteries or power sources are required increasing volume and complexity
Solution Approach 1:
The patent replaces the electrical ignition system with a purely mechanical inertial ignition system. Instead of using an electrical battery and ignition circuit, the invention uses a striker rod that physically impacts pyrotechnic material when accelerated by high-G forces during munitions firing. This mechanical substitution eliminates all electrical power source requirements, reducing volume and complexity while maintaining reliable ignition for the intended application.
4Volume of stationary object
If miniature inertial igniters are developed for small thermal batteries, then volume is reduced, but manufacturing precision and assembly difficulty increase
Solution Approach 1:
The patent achieves miniaturization while managing manufacturing precision through a standardized cylindrical housing design that serves multiple functions: containing the striker mechanism, providing structural support, and integrating with the thermal battery assembly. The locking balls and notches use simple geometric features that are easy to manufacture with standard tolerances. The spring and striker rod dimensions are optimized for the compact scale while maintaining functional reliability, balancing miniaturization with manufacturability.
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 miniature inertial igniters are significantly shorter and smaller in volume, ensuring safe and reliable ignition at high accelerations while preventing accidental ignition, with enhanced reliability and reduced manufacturing costs, allowing for extended storage and use in small thermal batteries.
Implementation Method 1
the striker mass is free to move in response to a high acceleration event, such that the striker mass converts the kinetic energy gained during the high acceleration event into mechanical impact energy to ignite a pyrotechnic compound
Implementation Method 2
the striker mass converts the kinetic energy gained during the high acceleration event into mechanical impact energy to ignite a pyrotechnic compound
Implementation Method 3
A setback spring is provided in compression between the collar and the base
Implementation Method 4
Two setback locking balls are provided in holes formed in the posts and in engagement with a concave portion on the striker mass
Data Source
AI summary
An ignition system for a thermal battery where the ignition system includes: a base plate for connection to the thermal battery; and two or more inertial igniters formed on the base plate, each of the two or more inertial igniters having a striker mass which ignites one or more pyrotechnic materials upon a predetermined acceleration profile, the base plate having an opening corresponding to each of the two or more inertial igniters for allowing a generated spark to pass into the thermal battery.