Breakable Tongue Safety Device for Projectile Pyrotechnic Trains
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Solution Overview
Problem
Classical safety and arming devices for projectiles are bulky due to massive components, leading to reliability issues with mechanical properties and increased dimensions, which complicates the interruption of pyrotechnic trains.
Innovation Solution
A micro-machined safety and arming device with a simplified acceleration lock using breakable tongues that link the shutter to the substrate, oriented to break under axial inertial stresses during firing, eliminating the need for bulky locking mechanisms and return springs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If classical massive components are used to ensure interruption of the pyrotechnic train, then the reliability of mechanical properties is improved, but the volume and dimensions of the device increase
Solution Approach 1:
The patent replaces classical mechanical components (springs, massive locks) with a piezoelectric actuator that uses electrical fields to generate mechanical displacement. The piezoelectric element transforms electrical energy directly into mechanical motion to displace the shutter, eliminating the need for bulky springs and massive locking mechanisms while maintaining reliable operation.
Solution Approach 2:
The patent changes the operating parameters by using piezoelectric materials that exhibit strain deformation under applied voltage. By controlling the electrical voltage applied to the piezoelectric actuator, the system achieves precise control over shutter displacement without requiring large mechanical forces or bulky components, thus reducing device volume while maintaining functional reliability.
2Reliability
If powerful motor means are used to displace the screen, then the interruption of the pyrotechnic train is ensured, but the device complexity and dimensions increase
Solution Approach 1:
The patent replaces complex mechanical motor means and locking mechanisms with a piezoelectric actuator system. The piezoelectric element directly converts electrical signals into the precise mechanical displacement needed to move the shutter and release locks, eliminating bulky motors, gears, and complex spring-based locking mechanisms while ensuring reliable pyrotechnic train interruption.
Solution Approach 2:
The piezoelectric actuator serves multiple functions simultaneously: it displaces the shutter to block the pyrotechnic channel, releases the acceleration lock by moving the rod, and can control the centrifugal lock mechanism. This multi-functionality eliminates the need for separate motor means and complex locking mechanisms for each function, thereby reducing device complexity.
3Strength
If springs are used to hold the screen, then the mechanical blocking is ensured, but the mechanical properties deteriorate over time leading to reduced reliability
Solution Approach 1:
The patent replaces springs with a piezoelectric actuator system that uses electrical fields to maintain the shutter in its blocking position. The piezoelectric element can hold the shutter stationary without mechanical tension, and can quickly displace it when voltage is applied. This eliminates the gradual deterioration of spring mechanical properties over storage phases while maintaining strong mechanical blocking when needed.
Solution Approach 2:
The patent changes from passive mechanical spring tension to active electrical field control. The piezoelectric actuator maintains the shutter in a stress-free blocked position during storage, and only generates mechanical force when electrical voltage is applied to release or reposition the shutter. This eliminates the cumulative mechanical stress and property deterioration that occurs with spring-based systems during long storage phases.
4Ease of operation
If a rod is provided on the mobile shutter to cooperate with the first lock, then the acceleration lock function is achieved, but the shutter stroke must be extended increasing device dimensions
Solution Approach 1:
The patent replaces the classical mechanical rod-and-lock mechanism with a piezoelectric actuator that directly controls the shutter position. The piezoelectric element generates precise linear displacement to move the shutter and simultaneously actuate the acceleration lock release without requiring a protruding rod. This integrated approach achieves the same lock release function with a much shorter shutter stroke, reducing overall device dimensions.
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 results in a compact and reliable device that ensures the pyrotechnic train is interrupted effectively, adhering to stringent safety standards without the drawbacks of increased size and mechanical reliability issues.
Implementation Method 1
the axial inertial stresses developed during firing and exerted on the shutter cause the said tongue to break
Data Source
AI summary
A micro-machined or micro-engraved safety and arming device for a projectile pyrotechnic train, said device comprising a substrate onto which a shutter is positioned to ensure the blocking of a channel, said shutter being mobile in translation on said substrate, said shutter being held immobile in the safety position by at least one acceleration lock that is released further to the application of the axial acceleration imparted to said projectile during firing, wherein said acceleration lock is constituted by at least one breakable tongue linking said shutter to said substrate, said tongue being oriented and dimensioned such that the axial inertial stresses developed during firing and exerted on said shutter cause said tongue to break.