Fusible Ring Safety Plug for Insensitive Ammunition Pressure Relief

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Solution Overview

Problem

Existing ammunition designs fail to ensure safety at higher temperatures, as they may explode or disintegrate when exposed to fire or high temperatures, necessitating enhanced safety measures for insensitive drive systems.

Innovation Solution

A detachable metal closure plug with a fusible ring or safety fuse is integrated into the cartridge, allowing internal pressure to escape before ignition, preventing explosive conversion of propellant powder through a hole in the propellant charge base, and utilizing a fusible material with a melting temperature below the ignition temperature.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If passages are filled with fusible material to prevent explosion at high temperatures, then safety at elevated temperatures is improved, but the device complexity increases due to additional components and assembly steps

Engineering Contradiction:
Improvesafety at elevated temperaturesVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the fusible material directly into the propellant charge base, merging the safety function with the existing structural component. This eliminates the need for separate passages and fusible material fillings, reducing device complexity while maintaining safety functionality.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The invention extracts the safety function from a separate component and integrates it directly into the propellant charge base. By taking out the need for separate fusible material fillings and passages, the solution simplifies the overall device structure while preserving the temperature-dependent safety mechanism.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If a detachable closure plug with fusible ring is used to relieve pressure before ignition, then bursting protection is improved, but the manufacturing process becomes more complex compared to drilling holes

Engineering Contradiction:
Improvebursting protectionVSAvoidease of manufacture
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the melting parameter of the fusible ring material to be lower than the ignition temperature of the propellant charge. This parameter change allows the ring to automatically open at a specific temperature, providing bursting protection through a simple temperature-dependent mechanism rather than complex manufacturing processes.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The fusible ring automatically opens at its melting temperature without requiring external activation or complex control systems. The material's inherent thermal properties enable it to perform the safety function autonomously, simplifying manufacturing compared to drilled holes that would require precise positioning and additional sealing components.

Inventive Principle:
Principle #25Self-service

3Reliability

If the sealing plug moves outwards without resistance at specified temperature, then pressure relief efficiency is improved, but the structural integrity of the cartridge may be compromised

Engineering Contradiction:
Improvepressure relief efficiencyVSAvoidstructural integrity
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent designs the fusible ring to melt and open the sealing plug at a predetermined temperature before the propellant charge reaches its ignition temperature. This preliminary action allows pressure to escape in advance, preventing catastrophic failure while maintaining structural integrity during normal storage and handling conditions.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The sealing plug is designed with localized fusible material only at the critical opening location, rather than compromising the entire cartridge structure. This localized approach allows the plug to move outwards without resistance at the sealing interface while maintaining the structural integrity of the rest of the cartridge body.

Inventive Principle:
Principle #3Local quality

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

This solution provides cost-effective bursting protection by relieving explosion pressure and ensuring slow combustion, maintaining safety and functionality even at elevated temperatures without drilling holes in the propellant charge case.

Implementation Method 1

The melting temperature of this material is lower than the ignition temperature of the pyrotechnic ignition device and the propellant charge

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 2

which prevents the propellant powder from being explosively converted and, at most, slow combustion

Methodology Applied
Scientific EffectCombustion: Combustion

Data Source

PatentEP2686636B1Non-sensitive ammunition
Publication Date: 2017.06.28 RHEINMETALL WAFFE MUNITION GMBH
  • EP2686636B1 patent drawingFigure 1~2
  • EP2686636B1 patent drawingFigure 3

AI summary

The invention provides cartridge ammunition (1), in particular of medium caliber, having a projectile (2) and a propellant charge casing (3) which is connected to the projectile (2), wherein a propellant charge (7) is provided in a propellant chamber (6) of the propellant charge casing (3) and has a functional connection to an igniting cap (11) of an ignition device, which is placed in a plug (14) that can be introduced into a hole (12) in the bottom (13) of the propellant charge casing (3). An annular gap (17, 17') is incorporated between the plug (14) and the propellant charge casing (3), which annular gap is led to the outside through the base (13) of the casing. The annular gap (17, 17') is sealed off with respect to the propellant charge (7) by a ring (16) and consists of a fusible, solid and pressure-tight material, the melting point of which lies at least below the melting point of the ignition temperature of the ignition device and the propellant charge (7). If the ammunition (1) is subjected to an excessively high temperature during the transport, storage, etc. thereof, the fusible material of the securing ring (16) begins to liquefy and passes through the annular gap (17, 17') to the outside. As a result of said measure, the plug (14) is released and loses the mechanical hold to the propellant charge casing (3). As a result, the plug (14) exposes the hole (12), so that a larger opening is produced in the base (13) of the casing.