Telescopic Pull-String Ignition for Munitions

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Solution Overview

Problem

Existing firing units for hand-held signal rockets, particularly those with lever release and rotary ignition mechanisms, suffer from issues such as undirected firing, lack of reversibility, and the risk of unintentional triggering due to permanent spring tensioning, which complicates handling and assembly.

Innovation Solution

A firing unit with a clamping sleeve, axially movable striking element, and a telescopic tensioning element that allows for controlled axial movement and secure locking, ensuring directed firing and reversibility, while preventing unintentional triggering through a telescopic mechanism that secures the tensioning element before release.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a lever release mechanism is used, then the signal rocket can be triggered, but the operator distorts the signal rocket and it shoots in an undirected manner

Engineering Contradiction:
Improvetriggering mechanismVSAvoidfiring direction
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical lever release system with a pull-string ignition system. The pull-string mechanism pulls a cord that triggers the firing pin axially, eliminating the need for manual lever manipulation that causes distortion. This substitution maintains ease of operation while ensuring precise axial firing direction.

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

Solution Approach 2:

Instead of pushing a lever to trigger ignition, the patent uses a pull-string mechanism where pulling the cord in the opposite direction (away from the rocket) triggers the firing. This inversion allows the operator to trigger the rocket without applying force that would distort the rocket body, maintaining both ease of operation and firing precision.

Inventive Principle:
Principle #13The other way round (Inversion)

2Ease of operation

If a rotary ignition mechanism is used, then ignition can be initiated, but there is a risk of tearing and it is comparatively expensive to manufacture

Engineering Contradiction:
Improveignition mechanismVSAvoidmanufacturing cost
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent replaces the complex rotary ignition mechanism with a simpler pull-string system. The pull-cord directly tensions and releases the firing pin through linear motion, eliminating rotary components, reducing manufacturing complexity and cost while maintaining ease of operation.

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

Solution Approach 2:

The patent extracts and removes the rotary movement component from the ignition system, keeping only the essential linear pulling action. This extraction simplifies the mechanism by eliminating unnecessary rotary parts, reducing manufacturing complexity while preserving the core ignition function.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If a spring is permanently tensioned to pre-load the firing pin, then the firing pin is ready to strike, but unintentional triggering is possible and spring force decreases over time

Engineering Contradiction:
Improveignition readinessVSAvoidunintentional triggering
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by pre-tensioning the spring and positioning the firing pin ready to strike, but keeps the system locked until the pull-string is actuated. The pull-string mechanism holds the tensioned spring in a controlled state, ensuring ignition readiness while preventing unintentional release through the locking mechanism.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The pull-string cord acts as an intermediary between the operator's action and the firing pin release. The cord transmits the pulling force through the tensioning mechanism to the firing pin, providing controlled mediation that prevents direct contact and unintentional triggering while maintaining spring tension for reliable ignition.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Ease of operation

If a tear-off fuse system is used, then the signal rocket can be triggered by tearing the cord, but it is not reversible and assembly is difficult

Engineering Contradiction:
Improvetriggering mechanismVSAvoidassembly process
Core Design Contradiction:
Ease of operationVSEase of manufacture

Solution Approach 1:

The patent uses a dynamic pull-string mechanism where the cord can be pulled to trigger ignition and then reset by pushing it back into place. This dynamic system allows the firing unit to transition between armed and disarmed states, enabling reversibility and simplifying assembly compared to permanent tear-off fuse systems.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements discarding and recovering by allowing the pull-string cord to be pulled out for triggering and then pushed back in for resetting and storage. The cord is not discarded after use but can be recovered and the system reset, enabling reversibility and simplifying assembly procedures.

Inventive Principle:
Principle #34Discarding and recovering

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 easy handling, reliable ignition with directed axial firing, and reversibility, preventing undirected pulling and unintentional triggering, while allowing secure stowage and reactivation of the firing unit.

Implementation Method 1

a spring (20) as a tensioning element for tensioning the striking element (90)

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3623741B1Launching unit for a munition
Publication Date: 2021.04.28 RHEINMETALL WAFFE MUNITION GMBH
  • EP3623741B1 patent drawingFigure 1
  • EP3623741B1 patent drawingFigure 2
  • EP3623741B1 patent drawingFigure 3

AI summary

The present invention relates to a launching unit for ammunition, in particular for a signal rocket, comprising a tension sleeve (30), a striking element (90) axially movable within the tension sleeve (30), a spring (20) for tensioning the striking element (90), and a pulling element (2) connected to the striking element (90), wherein the pulling element (2) is designed to be telescopically extendable in two parts.