Pyrotechnic Switch Contact Segmentation for High-Current Arc Interruption
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Solution Overview
Problem
Existing pyrotechnic switches for high current applications require large and costly actuators to break thicker conductors, leading to bulky and expensive switch arrangements, and struggle with effective arc interruption.
Innovation Solution
A switch design using three separate conductors with a temporary joint supported by a resilient member, where the pyrotechnic actuator applies smaller forces to break the joint, and optional arc extinguishing media and gas-generating elements enhance arc interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If large pyrotechnic actuators are used to break thicker conductors in high current applications, then the conductor breaking capability is improved, but the switch size and cost increase
Solution Approach 1:
The continuous conductor is divided into three separate conductor pieces (first, second, and third conductors) that are joined only at the contact interface. This segmentation allows the pyrotechnic actuator to break the electrical connection by separating the third conductor from the first and second conductors, rather than breaking a thick continuous conductor, significantly reducing the required actuator size and switch overall size while maintaining high current breaking capability.
2Strength
If large pyrotechnic actuators are used to break thicker conductors in high current applications, then the conductor breaking capability is improved, but the switch cost increases
Solution Approach 1:
The continuous conductor is divided into three separate conductor pieces (first, second, and third conductors) that are joined only at the contact interface. This segmentation allows the pyrotechnic actuator to break the electrical connection by separating the third conductor from the first and second conductors, rather than breaking a thick continuous conductor, significantly reducing the required actuator size and switch overall size while maintaining high current breaking capability.
3Reliability
If the third conductor is resiliently supported between the first and second conductors, then electrical contact is maintained in the closed position, but the force required to open the switch increases
Solution Approach 1:
The resilient member provides sufficient force to maintain reliable electrical contact in the closed position, but the pyrotechnic actuator generates excessive force (through gas expansion) to overcome this resilient support and rapidly separate the conductors in the open position. This partial/excessive action approach ensures both reliable contact closure and effective arc interruption through rapid separation.
Solution Approach 2:
The pyrotechnic actuator uses gas expansion (pneumatic principle) to generate the force needed to overcome the resilient member's holding force and rapidly separate the third conductor from the first and second conductors. The ignitable composition burns to produce expanding gas that pushes the piston, converting chemical energy to mechanical work for rapid conductor separation and arc extinction.
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 design results in smaller, cheaper switches with improved arc interruption and safety by reducing the force required for contact breakage and utilizing arc extinguishing media and gas-generating elements to increase arc resistance and extinguish arcs effectively.
Implementation Method 1
a pyrotechnic actuator arranged to release gas into the ignition chamber upon ignition
Implementation Method 2
a pyrotechnic actuator arranged to release gas into the ignition chamber upon ignition
Implementation Method 3
In the first position the third conductor is resiliently supported between, and in electrical contact with, the first and second conductors
Implementation Method 4
the movement of the moveable third conductor, relative to the first and second conductors, in response to the actuation (i.e. the linear translation of the third conductor) can rapidly stretch the arc, increasing the arc resistance
Implementation Method 5
The gas-generating element is formed of a material arranged to generate gas when exposed to the heat generated by the electrical arc
Data Source
Figure 1A
Figure 1B~1C
Figure 2
AI summary
A switch for opening a current conduction path is provided. The switch comprises an ignition chamber and a pyrotechnic actuator arranged to release gas into the ignition chamber upon ignition. The switch comprises first and second conductors, each comprising connection contacts. In a first position, a third, moveable, conductor of the switch is resiliently supported between, and in electrical contact with, the first and second conductors to define a current conduction path; in a second position, the third conductor is arranged to be electrically separate from the first and second conductors. The third conductor is moveable in a direction from the first position towards the second position in response to actuation by the pyrotechnic actuator. The switch may comprise at least one resilient member arranged to resiliently support the third conductor in the first position until actuation of the pyrotechnic actuator. A vehicle comprising the switch, and a method of operating the switch, are also provided.