Passive Pyrotechnic Triggering for Overcurrent Protection

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Solution Overview

Problem

Conventional electrical switching devices lack effective mechanisms for automatically interrupting circuits in response to overcurrent conditions, which can lead to device malfunction and safety hazards such as electrical fires, especially in advanced electrical systems like those in electric vehicles.

Innovation Solution

The integration of passive triggering mechanisms, including a pyrotechnic feature and a reed switch, which activates in response to a threshold magnetic field strength corresponding to elevated current levels, triggering a pyrotechnic actuator to interrupt the circuit and prevent further current flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional switching devices are used without passive triggering mechanisms, then the device complexity is reduced, but the reliability of overcurrent protection is insufficient

Engineering Contradiction:

Improveovercurrent protection reliabilityVSAvoidswitching device complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The passive triggering mechanism utilizes the overcurrent itself to generate the magnetic field that activates the reed switch, eliminating the need for external power sources or control circuits. The system serves itself by using the harmful overcurrent signal as the activation energy for the protection mechanism.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces complex electronic control systems with a passive magnetic field-based reed switch mechanism. The magnetic field generated by overcurrent directly actuates the reed switch, which then triggers the pyrotechnic feature, substituting elaborate electronic sensing and control circuitry with a simpler magnetic actuation system.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Speed

If passive triggering mechanisms are integrated into switching devices, then the response speed to overcurrent conditions is improved, but the device complexity increases

Engineering Contradiction:

Improveovercurrent response speedVSAvoidswitching device complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The reed switch acts as a passive intermediary component that converts the magnetic field signal from overcurrent into a mechanical activation signal for the pyrotechnic feature. This intermediary enables rapid response by directly coupling the magnetic field detection with the triggering mechanism without requiring complex electronic signal processing.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If the threshold current for triggering is lowered to improve safety, then the protection sensitivity is improved, but the likelihood of false triggering increases

Engineering Contradiction:

Improveovercurrent detection precisionVSAvoidfalse triggering rate

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent enables adjustment of the triggering threshold by modifying the distance between the reed switch and the power terminal, or by adjusting the magnetic field strength characteristics. This parameter adjustment capability allows optimization of the balance between sensitivity and false triggering rate based on specific application requirements.

Inventive Principle:

Principle #35Parameter changes

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 and automatic means to protect electrical devices from overcurrent damage and safety hazards by ensuring circuit interruption, even in high-current conditions, thereby enhancing safety and preventing permanent damage.

Implementation Method 1

The reed switch is arranged to be triggered by an overcurrent condition in the form of an elevated magnetic field generated by current flowing through the power terminal

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

A pyrotechnic actuator is also included that is arranged to be actuated by the trigger to physically interrupt the circuit by actuating the moveable contact

Methodology Applied

Scientific EffectPyrotechnic reaction: Combustion

Data Source

PatentUS11276535B2Passive triggering mechanisms for use with switching devices incorporating pyrotechnic features

Publication Date: 2022.03.15 GIGAVAC INC

AI summary

Disclosed herein are passive triggering mechanisms for activation of pyrotechnic features within electrical switching devices, such as contactor devices and fuse devices. The activation of the pyrotechnic features is configured to change the configuration of the internal components of the switching device and prevent current flow through the device. In some embodiments, the triggering mechanisms comprise features that respond to a magnetic field, such as a reed switch. In some embodiments, the reed switch responds to elevated current flow and can then use the signal with the elevated current flow to activate the pyrotechnic feature. In other embodiments, the reed switch uses a power signal from a secondary power source to activate the pyrotechnic feature.