Ammunition Firing Pin With Centrifugal Locking Mechanism

Solution Overview

Problem

Existing ammunition firing devices with mechanical firing pins are complex, costly, and unreliable, as they require precise machining and the self-destruct spring to be kept tensed during storage and transport, which can lead to unintended percussion and reduced performance over long storage periods and varying temperatures.

Innovation Solution

A simplified ammunition firing device with a sliding rod that is locked in its deployed position by centrifugal locks, where the percussion function is disassociated from the energy supply, allowing only firing stresses to prime the device, and utilizing MEMS technology to create a compact, reliable, and easy-to-manufacture design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a self-destruct spring is kept tensed during storage and transport, then the device can achieve self-destruction function, but the device complexity increases and reliability decreases due to risk of inadvertent percussion

Engineering Contradiction:

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The rod is pre-positioned inside the tip during assembly, with the tip already in place. The spring is compressed during firing rather than being pre-tensed during storage. This preliminary positioning of components in a safe state eliminates the need for maintaining spring tension during storage, reducing complexity and improving safety.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of keeping the spring tensed during storage and releasing it during firing, the invention inverts this sequence by keeping the spring relaxed during storage and compressing it during firing. The rod is initially inside the tip (safe state) and protrudes during firing (operational state), reversing the traditional approach.

Inventive Principle:

Principle #13The other way round (Inversion)

2Device complexity

If the firing pin is permanently aligned with the primer, then the device structure is simplified, but inadvertent percussion may occur during storage and transport

Engineering Contradiction:

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The rod dynamically changes position relative to the tip based on operational state. During storage, the rod is retracted inside the tip, preventing inadvertent percussion. During firing, the rod protrudes from the tip to strike the primer. This dynamic positioning maintains simple alignment structure while ensuring safety.

Inventive Principle:

Principle #15Dynamics

3Use of energy by moving object

If a substantial stroke is provided for the firing pin, then sufficient energy for ignition is ensured, but the device volume increases

Engineering Contradiction:

Core Design Contradiction:

Use of energy by moving objectVSVolume of moving object

Solution Approach 1:

The tip acts as an intermediary that amplifies the energy transfer. By positioning the rod inside the tip and having the hammer strike the rod, the tip concentrates and transmits the impact force efficiently to the primer. This intermediary mechanism enables sufficient ignition energy with a shorter stroke, reducing device volume.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Reliability

If precise machining is used for mechanical parts, then the device reliability is improved, but manufacturing cost and complexity increase

Engineering Contradiction:

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The centrifugal locks automatically engage and disengage based on rotational speed, without requiring precision-machined locking mechanisms or complex control systems. The simple geometric features (grooves, protrusions, ramps) perform the locking function through inertia alone, reducing manufacturing complexity and cost while maintaining reliability.

Inventive Principle:

Principle #25Self-service

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 enables a compact, reliable, and efficient firing device that maintains performance over long storage and varying temperature conditions without the need for a tensed spring, ensuring safe storage and reliable ignition, while reducing manufacturing complexity and costs.

Implementation Method 1

a firing pin incorporating a rod which slides under the effect of the firing acceleration from a starting position to a deployed position

Methodology Applied

Scientific EffectInertia: Inertia

Implementation Method 2

such rod being locked in the deployed position by at least one centrifugal lock

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 3

a hammer to strike the rod during the impact of the ammunition on a target to cause the ignition of the composition

Methodology Applied

Scientific EffectImpact force: Impact Force

Data Source

PatentUS8104405B2Ammunition firing device incorporating a firing pin

Publication Date: 2012.01.31

AI summary

An ammunition firing device incorporating a firing pin intended to impact a pyrotechnic composition to activate its ignition, wherein said firing pin incorporates a rod that slides when said ammunition is fired through the effect of the firing acceleration from a starting position to a deployed position, able to be locked in said deployed position, said rod being integral with a percussion tip occupying a fixed position in contact with said pyrotechnic composition, said rod being located fully inside said tip in said starting position and protruding from said tip in its deployed position, said device further incorporating a hammer to strike said rod during the impact of said ammunition on a target to cause the ignition of said composition.