Projectile Fuze Safety Device Using Acceleration Sensor

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Solution Overview

Problem

Existing safety devices for projectile detonators require manual intervention to unlock, leading to potential unintentional activation issues, as they rely on mechanical pins or launch-related parameters, which can be forgotten or misinterpreted.

Innovation Solution

A safety device that utilizes a sensor unit to detect a state of weightlessness or low acceleration, independent of launch parameters, to output a release signal for unlocking the ignition process, ensuring secure ignition only during flight phases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a manual locking pin is used to secure the detonator, then the safety device can prevent unintentional activation, but the locking pin may be forgotten or left in place, causing the mortar shell to become a dud

Engineering Contradiction:

Improveprevention of unintentional activationVSAvoidmanual pin removal

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The safety device automatically determines whether to unlock based on detected acceleration patterns, eliminating the need for manual intervention. The system serves itself by autonomously deciding when the projectile is ready for firing based on physical motion characteristics

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The manual mechanical pin system is replaced with an electronic control system that uses acceleration sensors and a microcontroller to automatically control the locking mechanism, substituting mechanical operation with electronic automation

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If launch shock detection is used to unlock the safety device, then the detonator can be activated after firing, but the detection may be misinterpreted or unreliable

Engineering Contradiction:

Improveunlocking after launchVSAvoidacceleration detection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The safety device unlocks in advance based on detected acceleration patterns indicating launch, rather than waiting for shock detection. The system prepares the ignition system before the actual firing moment by recognizing the acceleration signature of launch

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses dynamic acceleration patterns over time to determine launch status, analyzing the temporal characteristics of motion rather than relying on a single static threshold. This allows reliable distinction between launch conditions and other acceleration events

Inventive Principle:

Principle #15Dynamics

3Reliability

If a sensor unit detects weightlessness or low acceleration state to unlock the safety device, then security against unintentional ignition is improved, but the device complexity increases

Engineering Contradiction:

Improvesecurity against unintentional ignitionVSAvoidsensor unit and control system

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The acceleration sensor system serves multiple functions: it detects launch conditions for unlocking, monitors flight status, and provides data for ignition timing decisions. This multi-functionality justifies the added complexity by eliminating separate sensor systems

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system monitors changes in acceleration parameters over time to detect specific states (launch, flight, impact). By analyzing temporal variations in acceleration rather than single values, the system achieves reliable state detection with relatively simple threshold-based logic

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

This solution provides a high level of security against unintentional ignition by using the weightlessness state as an arming parameter, ensuring the detonator remains secure until it reaches a predetermined low-acceleration state, characteristic of flight, thereby preventing accidental activation.

Implementation Method 1

a sensor unit which is prepared for, when the igniter is accelerating, which is at least a specified acceleration value below the acceleration due to gravity, to output a release signal

Methodology Applied

Scientific EffectGravitation: Gravitation

Data Source

PatentEP2513594B1Safety device for a fuze of a projectile

Publication Date: 2017.01.04 JUNGHANS MICROTEC

AI summary

The invention relates to a safety device (2) for a fuse (4) of a projectile, which comprises a detonating device for detonating the fuse (4), comprising a safety unit having a processing means (34) for safeguarding a detonation process of the detonating device. According to the invention, the safety unit contains a sensor unit (38) which is set up to output a disengagement signal at a predetermined acceleration state, wherein the processing means (34) is set up to output a control signal to release the safety unit in accordance with the presence of the disengagement signal. A low-acceleration state of the flight of the projectile can thus be detected and used as release parameter.