Pyrotechnic Switch Cylindrical Contact Segmentation

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Solution Overview

Problem

Existing electrical switches actuated by pyrotechnic devices face issues with high force requirements, manufacturing complexity, and unsuitable contact interfaces for high-intensity currents, leading to potential arcing and reliability concerns.

Innovation Solution

A switch design featuring elongated flat ends with cylindrical openings and parallel contact surfaces, a combustion chamber, and a pyrotechnic device generating pressurizing gas to move a moveable body for connection, ensuring reliable and low-friction contact without additional parts maintaining the connection, and using sealing means to isolate the pressurizing gas from conductive components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a slider is used to connect terminals with biased surfaces, then the switch can maintain connecting position, but the manufacturing tolerances become extremely important and the cost increases

Engineering Contradiction:
Improvereliable functioningVSAvoidcomplexity of shapes
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The switch is divided into separate functional components: a moveable body with contact surfaces, terminals with contact portions, and a combustion chamber. This segmentation allows each part to be manufactured independently with standard tolerances, eliminating the need for extremely tight tolerances on assembled biased surfaces while maintaining reliable electrical connection.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The complex mechanical biased surface guidance system is replaced with a simpler cylindrical contact portion design. The cylindrical geometry provides inherent alignment and connection without requiring precision-machined biased surfaces, reducing manufacturing complexity while ensuring reliable electrical contact.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If biased surfaces are used to maintain connecting position, then the slider can be held in position, but the contact interface is insufficient for high intensity currents causing electric arcs

Engineering Contradiction:
Improvemaintaining connecting positionVSAvoidelectric arcs
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The contact portions and contact surfaces are designed with cylindrical geometry rather than flat biased surfaces. This curved surface design increases the contact area between moving and stationary contacts, distributing the current density and preventing electric arcs and overheating while maintaining reliable positional connection.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The contact interface parameters are changed from line contact (biased surfaces) to surface contact (cylindrical surfaces). This parameter change increases the contact area, reducing current density and eliminating electric arcs for high intensity current applications while maintaining the holding function.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If a pyrotechnic device is made powerful to push the slider, then reliable actuation is ensured, but the cost increases

Engineering Contradiction:
Improvereliable actuationVSAvoidpowerful pyrotechnic device
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The guidance and connection function is extracted from the pyrotechnic device and assigned to the cylindrical contact portions and surfaces. This allows the use of a less powerful, simpler, and cheaper pyrotechnic device since it only needs to move the moveable body along the cylindrical path, not overcome complex biased surface friction and misalignment forces.

Inventive Principle:
Principle #2Taking out (Extraction)

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 switch that is easy to manufacture, reliable, and capable of handling high-intensity currents without arcing or overheating, while reducing costs and ensuring the electrical pyrotechnic device's safety from conductive gases.

Implementation Method 1

an electrical pyrotechnic device arranged to generate pressurizing gas in the combustion chamber to move the moveable body from the first position to the second position

Methodology Applied
Scientific EffectCombustion: Combustion

Data Source

PatentEP2901467B1Electrical pyrotechnic switch
Publication Date: 2017.08.30 AUTOLIV DEV AB
  • EP2901467B1 patent drawingFigure 1~3

AI summary

Electrical switch comprising: - a first conductive terminal comprising a first contact portion, - a second conductive terminal comprising a second contact portion, - a moveable body moveable from a first position, in which the first and second contact portions are electrically disconnected, to a second position, in which the first and second contact portions are electrically connected, characterized: - in that said first and second contact surfaces are cylinders parallel to respectively said first and second contact portions, - in that the second contact surface freely goes through the first contact portion, - in that the first contact surface enters in connection with the first contact portion simultaneously to the moment when the second contact surface enters in connection with the second contact portion, - and in that at least one of said first and second surfaces and the corresponding one of the first and second contact portions are arranged so that the moveable body is maintained in the second position.