EFI Output Charge Sizing for Single-Interface Main Charge Detonation

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Solution Overview

Problem

Conventional explosive firing trains require precise gapping and multiple explosive transfer interfaces to ensure reliable detonation of high explosives, which are costly and complex, especially in military-grade munitions, where safety and reliability are critical.

Innovation Solution

An EFI with an output charge formed from booster explosive material and a diameter greater than the barrel, eliminating one transfer interface and directly detonating the main charge, while incorporating vent holes for safety, enhances detonation energy and reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional explosive firing trains use multiple explosive transfer interfaces with precise gapping, then reliable detonation of main charge is achieved, but device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improvereliable detonationVSAvoidmultiple transfer interfaces

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the intermediate fuze booster and its associated explosive transfer interfaces from the conventional firing train. The EFI directly initiates the main charge, eliminating unnecessary components and interfaces while maintaining reliable detonation through direct coupling of the initiator to the main charge.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the initiator and main charge into a simplified firing train configuration where the EFI directly couples to the main charge. This consolidation eliminates the intermediate booster stage and reduces the number of explosive transfer interfaces from two to one, simplifying the overall device structure.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If conventional explosive firing trains use two explosive transfer interfaces, then detonation energy is transferred through intermediate booster, but manufacturing precision requirements increase

Engineering Contradiction:

Improvedetonation energy transferVSAvoidprecise gapping

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent extracts and removes the intermediate fuze booster component that requires precise gapping at two separate interfaces. By eliminating this intermediate stage, the design reduces manufacturing precision requirements while maintaining effective detonation energy transfer through direct initiation of the main charge.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If EFI output charge diameter is increased to enhance detonation energy, then main charge detonation reliability improves, but EFI device dimensions increase

Engineering Contradiction:

Improvemain charge detonationVSAvoidEFI diameter

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent changes the diameter parameter of the EFI output charge to be greater than the barrel diameter, optimizing the detonation energy output. This parameter adjustment ensures sufficient energy transfer to reliably detonate the main charge while accepting the resulting increase in EFI device dimensions as a necessary trade-off.

Inventive Principle:

Principle #35Parameter changes

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 EFI provides enhanced detonation energy to reliably detonate the main charge, simplifying the firing train and reducing complexity, thus improving safety and reliability in military-grade munitions.

Implementation Method 1

In response to an electric stimulus, the circuit propels a flyer through the barrel's through hole to impact and detonate the output charge

Methodology Applied

Scientific EffectElectrical energy to mechanical energy conversion: Electromagnetic Induction

Implementation Method 2

The detonation wave from the EFI's output charge impacts the single explosive transfer interface with sufficient detonation energy to detonate the main charge

Methodology Applied

Scientific EffectDetonation: Detonation

Data Source

PatentUS12560418B1Explosive firing train with a single explosive transfer interface

Publication Date: 2026.02.24 RAYTHEON CO

AI summary

An EFI or LEEFI provides enhanced detonation energy sufficient to directly detonate a main charge to improve the reliability and ease the qualification of an explosive firing train. This is accomplished by forming the EFI's output charge from an explosive material typically used as a booster explosive (e.g., PBXN-5, CH-6 and Composition A5) rather than a primary explosive and making the diameter of the output charge greater than the diameter of the barrel thus increasing the total mass of the output charge. The explosive firing train now requires only a single explosive transfer interface. For use in military grade munitions, the EFI's casing is formed with one or more vent holes radially adjacent the output charge.