Bistable Switch Power Supply Circuit for Aeroengine Thermal Cutoff

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Solution Overview

Problem

Existing power supply circuits for aeroengine computers are unreliable in preventing unwanted engine restarts due to unpredictable behavior during overheating, and irreversible cutoffs restrict pilot control over engine operation.

Innovation Solution

A power supply circuit with a bistable switch controlled by magnetic fields induced by coils and a thermal resistor, allowing reversible cutoff of power to electronic cards during overheating, enabling safe shutdown and potential restart based on temperature conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an irreversible cutoff is implemented using non-volatile memory to store overheating detection information, then the reliability of engine shutdown is improved, but the adaptability of the system is worsened because the pilot cannot restart the engine

Engineering Contradiction:

Improvereliability of engine shutdownVSAvoidpilot control over engine restart

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system transitions from a static irreversible cutoff to a dynamic reversible cutoff by using a bistable switch that can change states based on control signals. The switch maintains its state (either cutoff or powered) until actively changed by a control signal, enabling both reliable shutdown and controlled restart capabilities

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the state parameter of the power supply circuit from irreversible to reversible by modifying the cutoff mechanism. Instead of permanently storing cutoff status in non-volatile memory, the system uses a bistable switch whose state can be changed by control signals, allowing the cutoff condition to be reversed when needed

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If a simple cutoff mechanism is used without thermal memory, then the ease of operation is improved, but the reliability is worsened because unwanted commands may be issued during unpredictable overheating behavior

Engineering Contradiction:

Improvesimplicity of cutoff mechanismVSAvoidprevention of unwanted engine restart

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The bistable switch acts as an intermediary element between the simple cutoff mechanism and the thermal memory function. It provides the necessary reliability by maintaining its state based on thermal conditions while keeping the overall mechanism relatively simple through the use of standard electromagnetic components

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If non-volatile memory is used to store overheating detection, then the reliability of preventing unwanted restart is improved, but the device complexity increases due to additional memory components

Engineering Contradiction:

Improveprevention of unwanted engine restartVSAvoidcomplexity of power supply circuit

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system replaces complex electronic memory storage with a simpler electromagnetic bistable switch mechanism. Instead of using non-volatile memory components to store cutoff status, the system uses the magnetic properties of coils and a bistable switch to maintain state information, reducing device complexity while maintaining reliability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Ensures reliable engine shutdown during overheating while allowing pilot-controlled restarts, preventing unwanted engine reactivation and ensuring safe operation.

Implementation Method 1

a first switch controlled by a cutoff signal that is connected between the input terminal and a series circuit comprising a thermal resistor and a first coil, said series circuit lying between said first switch and a ground terminal

Methodology Applied

Scientific EffectMagnetic field induction: Electromagnetic Induction

Implementation Method 2

a second switch controlled by a reinitialization signal and a second coil in series with between the input terminal and the ground terminal

Methodology Applied

Scientific EffectMagnetic field induction: Electromagnetic Induction

Implementation Method 3

a series circuit comprising a thermal resistor and a first coil

Methodology Applied

Scientific EffectThermal resistance effect: Thermistor

Implementation Method 4

the bistable switch being configured to switch to the first state when the magnetic field induced by the second coil is greater than the magnetic field induced by the first coil, and to switch to the second state when the magnetic field induced by the first coil is greater than the magnetic field induced by the second coil

Methodology Applied

Scientific EffectMagnetic field interaction: Magnetic Field

Data Source

PatentUS9887058B2Power supply circuit

Publication Date: 2018.02.06 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A power supply circuit for electronic equipment that might be affected by overheating or by a fire, the power supply circuit including a bistable switch switchable between a first state in which the input terminal is connected to the output terminal, and a second state in which the input terminal is not connected to the output terminal, a first coil, and a second coil, the bistable switch being configured to switch to the first state when the magnetic field induced by the second coil is greater than the magnetic field induced by the first coil, and to switch to the second state when the magnetic field induced by the first coil is greater than the magnetic field induced by the second coil.