Pyrotechnic Circuit Breaker Piston Rotation Prevention

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Solution Overview

Problem

Conventional pyrotechnic circuit breakers face reliability issues due to the piston's tendency to rotate and improperly cut soft or thin bus bars, leading to reduced effectiveness in disconnecting electrical circuits.

Innovation Solution

The design incorporates a piston with a second protrusion that engages the bus bar before the cutting edge, preventing rotation and ensuring accurate cutting by maintaining the bus bar in position until it is fully severed, utilizing a drawer system and elongated protrusions and apertures to enhance guidance and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the piston is propelled by the pyrotechnic igniter to cut the bus bar, then the circuit breaker can open the circuit, but the piston may rotate around its axis and bend or improperly cut the bus bar

Engineering Contradiction:
Improvereliability of circuit breakerVSAvoidproper cutting of bus bar
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent introduces a guiding structure consisting of guide slots in the body and guide protrusions on the piston that act as intermediary elements. These guide components constrain the piston's movement path, preventing rotation around its axis during the cutting operation. The guide slots and protrusions work together to ensure the piston moves only in the intended linear direction, thereby eliminating the harmful rotation while maintaining the cutting function.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If the bus bar material is soft or the bus bar is thin, then the piston may bend the bus bar instead of cutting it properly, but increasing piston force may damage the bus bar

Engineering Contradiction:
Improvecutting precision of bus barVSAvoidintegrity of bus bar
Core Design Contradiction:
Manufacturing precisionVSStrength

Solution Approach 1:

The patent positions the cutting edge of the piston to engage the bus bar at a predetermined location before the piston completes its full stroke. This preliminary positioning ensures that the cutting action begins at the correct point, allowing the bus bar to be severed cleanly without excessive force. The guide structure also ensures the cutting edge approaches the bus bar perpendicular to its length, optimizing the cutting action for both soft and thin materials.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If the piston rotates during cutting, then the cutting accuracy decreases and the circuit breaker reliability is reduced, but preventing rotation requires additional guiding structures

Engineering Contradiction:
Improvecutting accuracyVSAvoidcomplexity of piston guidance system
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent integrates the guiding function directly into the existing piston and body structures by incorporating guide slots into the body housing and guide protrusions onto the piston surface. This merging of guidance features with the primary components eliminates the need for separate, additional guiding mechanisms. The guide slots and protrusions are formed as integral parts of the assembly, maintaining cutting accuracy while avoiding excessive complexity.

Inventive Principle:
Principle #5Merging (Combining)

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 configuration significantly improves the reliability of the pyrotechnic circuit breaker by ensuring precise cutting and maintaining the bus bar's position during the cutting process, reducing the risk of rotation and enhancing electrical insulation.

Implementation Method 1

Upon activation of the pyrotechnic igniter, the piston quickly starts moving from the first position to the second position

Methodology Applied
Scientific EffectPyrotechnic combustion: Combustion

Implementation Method 2

the cutting edge comes into contact with the bus bar to break it into two distinct parts, thereby stopping the electrical conductivity of the bus bar

Methodology Applied
Scientific EffectMechanical cutting: Fracture Mechanics

Data Source

PatentEP3401940B1Pyrotechnic circuit breaker
Publication Date: 2021.06.23 ARIANEGRP SAS
  • EP3401940B1 patent drawingFigure 1A
  • EP3401940B1 patent drawingFigure 1B
  • EP3401940B1 patent drawingFigure 2A

AI summary

The invention related to a pyrotechnic circuit breaker (1) comprising: a body (10), a piston (40) slidably mounted in said body along a first direction (Z), said piston having a first protrusion (42) comprising a cutting edge (42a), a pyrotechnic igniter (30), and a bus bar (50). The piston is adapted to move from a raised position to a lowered position to cut the bus bar into two distinct portions (50a, 50b) upon activation of the pyrotechnic igniter (30). The piston further comprises a second protrusion (44a) extending from the lower face (43) over a greater distance (dl) than the first protrusion (d2). The bus bar (50) comprises an aperture (52a) aligned along the first direction (Z) with said second protrusion (44a), the second protrusion and the aperture being adapted to cooperate such that the second protrusion is engaged in the aperture when the piston moves from the first position to the second position.