Safety Arming Device for Instant Impact Point Fuse
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Solution Overview
Problem
Existing safety and arming devices for instant impact point fuses on gyratory projectiles are inadequate, particularly for medium-caliber munitions, as they do not effectively prevent premature alignment of the primer with the striker, and fail to meet the double safety requirements of standards like STANAG 4187.
Innovation Solution
A safety and arming device for an instant impact point fuse featuring a rotor with a sleeve held out of alignment by a spring, which includes a flyweight that, upon longitudinal acceleration, pushes a lever to separate the sleeve from the rotor, allowing the rotor to pivot and release, ensuring the primer is aligned with the striker only during firing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sleeve blocks the rotor in a non-aligned position, then safety is improved, but the device complexity increases
Solution Approach 1:
The safety device integrates multiple functional elements within a compact nested structure. The sleeve is positioned within the fuse body, the flyweight is nested within the sleeve assembly, and the lever mechanism is integrated into the overall structure. This nesting approach provides comprehensive safety functionality while minimizing the increase in device complexity.
Solution Approach 2:
The device implements preliminary safety actions through the sleeve that pre-blocks the rotor in a non-aligned position before firing. The flyweight is pre-positioned within the sleeve, and the spring is pre-compressed to provide the necessary blocking force. This preliminary arrangement ensures safety is established before the firing sequence begins.
2Reliability
If a double safety mechanism is added, then reliability is improved, but the device complexity increases
Solution Approach 1:
The patent merges the double safety mechanism into a single integrated assembly where the sleeve and flyweight work together as one cohesive unit. The first safety function (blocking) and the second safety function (release upon acceleration) are combined in the same structural arrangement, providing dual safety protection without requiring entirely separate mechanisms.
Solution Approach 2:
The sleeve assembly serves multiple functions: it provides the first safety by blocking the rotor, houses the flyweight for the second safety function, and contains the spring mechanism. This multi-functionality approach allows the device to achieve double safety protection while minimizing the increase in overall device complexity.
3Reliability
If the sleeve is permanently separated from the rotor, then safety is improved, but the ease of operation deteriorates
Solution Approach 1:
The device transitions from a static blocking arrangement to a dynamic system where the flyweight responds to acceleration forces. During normal handling, the spring maintains the blocking position. During firing, the acceleration causes the flyweight to move outward, dynamically releasing the block. This dynamic behavior ensures safety during operation while allowing proper function during firing.
Solution Approach 2:
The device uses changes in acceleration parameters to trigger the safety release. The spring force maintains the blocked state under normal conditions, but when acceleration exceeds a threshold during firing, the flyweight overcomes the spring force and moves to release the rotor. This parameter-based control ensures safety during handling while enabling operation during firing.
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 reliable double safety mechanism that prevents premature ignition by ensuring the primer is not aligned with the striker until the projectile is in flight, meeting the requirements of STANAG 4187 and ensuring safe operation during handling and impact.
Implementation Method 1
a flyweight intended, when it is subjected to the longitudinal acceleration resulting from the shot, to exert a pushing force on a first end of at least one lever
Implementation Method 2
a sleeve pressed against a flat spot of the rotor by a spring
Data Source
AI summary
A safety and arming device for an instant impact point fuse for a gyratory projectile and a fuse equipped with such a device. The device includes a rotor carrying a primer held in a safe, non-aligned position with respect to a striker by a sleeve pressed against a flat spot of the rotor. The device also includes a flyweight that, when subjected to the longitudinal acceleration resulting from the shot, exerts a pushing force on a first end of at least one lever, the second end of the at least one lever being located below a collar of the sleeve. The pushing force of the flyweight causes the lever(s) to pivot about a pivot point, the pivoting of the lever then separates the sleeve from the flat spot of the rotor permanently, releasing the rotor.