Water-Corroding Electrical Protection Device for Safe Power Cutoff

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Solution Overview

Problem

Existing protective devices for electrical devices do not effectively and safely switch off the power supply when water enters, potentially causing uncontrolled failures due to electrolysis, and existing solutions are not non-toxic or ROHS-compatible.

Innovation Solution

A protective device made from rapidly corroding materials like magnesium, aluminum, or lanthanide metals, which interrupt the current-conducting cross-section upon corrosion, with optional surface coatings to control the response to water exposure, ensuring safe and reliable power cutoff.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a rapidly corroding material is used to interrupt current upon water exposure, then reliability of power cutoff is improved, but device complexity increases due to material selection and coating requirements

Engineering Contradiction:
Improvepower cutoff reliabilityVSAvoidprotective device structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the chemical composition parameters of the protective device by using rapidly corroding materials like magnesium, aluminum, or their alloys instead of conventional fuse materials. This parameter change enables the device to react quickly to water exposure through accelerated corrosion, ensuring reliable power cutoff while maintaining a simple structural design.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material structures by combining rapidly corroding base metals with protective coatings (such as lacquer or oxide layers). This composite approach allows the device to remain stable under normal conditions while rapidly corroding when exposed to water, thus achieving reliable power cutoff without requiring complex mechanical structures.

Inventive Principle:
Principle #40Composite materials

2Speed

If a metal with high corrosion sensitivity is used, then response speed to water exposure is improved, but manufacturing difficulty increases due to handling and assembly constraints

Engineering Contradiction:
Improvecorrosion response speedVSAvoidassembly ease
Core Design Contradiction:
SpeedVSEase of manufacture

Solution Approach 1:

The patent applies preliminary protective actions by pre-coating the rapidly corroding metal with protective layers such as lacquer, oxide films, or phosphate coatings during manufacturing. This preliminary protection allows the metal to be handled and assembled like conventional materials without premature corrosion, while still maintaining rapid corrosion response capability when the protective layer is compromised by water exposure.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent modifies the surface parameters of the metal by applying various coatings that control the corrosion rate. These coating parameters can be adjusted during manufacturing to balance corrosion sensitivity with ease of handling and assembly, allowing standard manufacturing processes to be used while achieving rapid response when needed.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If surface coating is applied to control corrosion sensitivity, then selectivity of water response is improved, but manufacturing complexity increases due to additional coating processes

Engineering Contradiction:
Improvewater response selectivityVSAvoidmanufacturing process complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent uses surface coating parameters (thickness, composition, porosity) to control and tune the corrosion sensitivity of the protective device. By adjusting these parameters, the device can be made selectively responsive to different levels or types of water exposure, enabling adaptability without requiring complex multi-component structures or multiple separate devices.

Inventive Principle:
Principle #35Parameter changes

4Object-affected harmful factors

If non-toxic and ROHS-compatible materials are used, then environmental compatibility is improved, but corrosion sensitivity may be reduced

Engineering Contradiction:
Improveenvironmental compatibilityVSAvoidcorrosion response reliability
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent uses composite material structures combining environmentally compatible base metals (magnesium, aluminum, or their alloys) with protective coatings. This composite approach maintains the non-toxic and ROHS-compatible nature of the materials while ensuring reliable corrosion response through the synergistic interaction between the reactive base metal and the protective layer that controls corrosion kinetics.

Inventive Principle:
Principle #40Composite materials

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 ensures a safe and reliable power cutoff upon water exposure, preventing uncontrolled failures and meeting non-toxic and ROHS-compatibility requirements, while maintaining electrical functionality.

Implementation Method 1

the protective device consists of a rapidly corroding material which, in the event of corrosion, interrupts a current-conducting cross-section in the electrical device

Methodology Applied
Scientific EffectCorrosion: Crevice Corrosion

Implementation Method 2

The water that has penetrated the electrical device can then cause uncontrolled failures as a result of electrolysis

Methodology Applied
Scientific EffectElectrolysis: Electrolysis

Implementation Method 3

water gets through the electrical plug connection to the electrical device, in particular a cable harness, through leaky cables into the strands of the connecting cable and flows via capillary action along the strand into the device plug

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Data Source

PatentEP2476131B1Protection device for an electric unit
Publication Date: 2016.07.27 ROBERT BOSCH GMBH
  • EP2476131B1 patent drawingFigure 1~4

AI summary

The invention relates to a protection device (10; 30; 40; 50) for an electric unit (52), wherein the protection device (10; 30; 40; 50) is disposed in a current-carrying line (13; 35; 46; 54) for the electric unit (52) and brings about a disconnection of the power supply to the electric unit (52) when a critical operating state occurs. According to the invention, at least one section of the protection device (10; 30; 40; 50) is made, across the entire cross-sectional area thereof, of a material that corrodes under the influence of water, and the current-carrying cross-sectional area of the protection device (10; 30; 40; 50) is disconnected in case of corrosion.