Purely Pyrotechnic Hand Grenade Fuze System Design

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Solution Overview

Problem

Existing hand grenade fuze systems face challenges in reliability, price, environmental adaptability, hazardous material usage, and mass explosion safety, with pyrotechnic-mechanical systems being complex and expensive, and electronic systems lacking reliability.

Innovation Solution

A purely pyrotechnic detonator system with two independent ignition delay devices, where a safety element with a shorter delay time ignites a gas charge to open shut-off elements, and a delay element with a fire charge only activates the detonator after the shut-off elements are open, ensuring a simple, safe, and cost-effective functional principle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If pyrotechnic-mechanical ignition systems are used, then reliability and safety are improved, but device complexity and price increase

Engineering Contradiction:
Improveignition reliabilityVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical clockwork mechanism with a purely pyrotechnic timing system. Two pyrotechnic delay elements with different burn rates create a timing mechanism that eliminates complex mechanical moving parts while maintaining reliable ignition sequencing. The faster-burning element triggers the detonator after a short delay, while the slower-burning element provides a longer safety delay, achieving reliable ignition without mechanical complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The ignition system is segmented into two independent pyrotechnic delay elements with distinct functions. The first element (faster burn rate) provides the primary ignition timing, while the second element (slower burn rate) provides a safety delay mechanism. This segmentation allows each element to be optimized for its specific function, improving overall reliability while keeping the system simple and modular.

Inventive Principle:
Principle #1Segmentation

2Reliability

If pyrotechnic-mechanical ignition systems are used, then safety is improved, but price increases

Engineering Contradiction:
Improveignition safetyVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

By replacing expensive mechanical clockwork mechanisms with pyrotechnic delay elements, the patent achieves high safety standards at lower manufacturing costs. Pyrotechnic elements are simpler to manufacture, require fewer precision-machined parts, and can be produced more efficiently while maintaining reliable safety delays.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses consumable pyrotechnic delay elements that are designed to be used once and then discarded. These elements are inexpensive to manufacture compared to mechanical mechanisms, and their single-use nature ensures consistent performance without the need for maintenance or adjustment, reducing overall system cost while maintaining safety.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Device complexity

If electronic detonation systems are used, then device complexity is reduced, but reliability decreases

Engineering Contradiction:
Improvesystem complexityVSAvoidignition reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent avoids electronic systems entirely by using pyrotechnic delay elements that provide inherently reliable timing through controlled combustion rates. This pyrotechnic approach eliminates electronic components that are susceptible to failure from moisture, temperature extremes, and manufacturing defects, achieving both simplicity and high reliability in harsh environmental conditions.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 system provides a reliable, safe, and cost-effective ignition mechanism that is operational in all environmental conditions, preventing premature ignition and ensuring the detonator is securely transitioned from a safety to an ignition position, enhancing safety standards.

Implementation Method 1

Heat is generated when the ignition retarder burns through. This melts a solder fuse after two seconds.

Methodology Applied
Scientific EffectHeat generation through combustion: Combustion

Implementation Method 2

the gas of which opens shut-off elements

Methodology Applied
Scientific EffectGas pressure generation: Pressure Increase

Implementation Method 3

the delay element contains a fire charge and only after the shut-off elements have been opened the fire charge is in operative connection with the detonator

Methodology Applied
Scientific EffectPyrotechnic ignition: Combustion

Data Source

PatentEP3230682B1Fuze system for hand grenades
Publication Date: 2019.01.30 RUAG AMMOTEC AG
  • EP3230682B1 patent drawingFigure 1
  • EP3230682B1 patent drawingFigure 2a~2c
  • EP3230682B1 patent drawingFigure 3a

AI summary

The invention relates to an igniter system for hand grenades with an igniting element (1), which after initiation triggers a delay and safety device, which with a time delay after the initiation fires a detonator (7), which subsequently ignites an ignition booster (8), wherein the delay and safety device comprises a dual safety device of two independent parts. In order that the igniter system according to the invention for hand grenades comprises a purely pyrotechnical igniter system instead of a pyrotechnical-mechanical system, it is proposed that the delay and safety device consists of two pyrotechnic ignition delays with different delay times, that is to say a safety element (3) and a delay element (4), wherein the delay time of the safety element (3) is shorter than the delay time of the delay element (4) and the safety element (3) comprises a timer which carries out ignition after the burning off of a gas charge (9), the gas of which opens blocking elements (5), and the delay element (4) comprises a firing charge, and the firing charge is only in operative connection with the detonator (7) after the opening of the blocking elements (5).