Latching Thermostat Overheat Protection Redundant Heating

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Redundant heating systems in aircraft, such as drain masts, face failures due to stuck-on conditions where heating circuits continue to raise temperatures beyond safe limits, leading to thermal cutoffs and subsequent inoperability, causing damage or rendering systems inoperative.

Innovation Solution

Incorporating latching thermostats in series with heating elements, which switch to a high-resistance state when reaching an open latch threshold temperature, diverting power to a thermistor and reducing heat output, preventing overheating and allowing systems to recover when temperatures fall below a close latch threshold.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a heating circuit continues to operate after a stuck-on failure, then the heating element remains active, but the temperature exceeds safe limits causing thermal cutoff and system inoperability

Engineering Contradiction:

Improveheating circuit operationVSAvoidoverheating damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A latching thermostat is introduced as an intermediary component between the temperature controller and heating element. The thermostat monitors temperature and acts as a safety mediator that automatically opens the circuit when overheating is detected, preventing damage while allowing continued operation of the heating circuit through recovery mechanisms

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The latching thermostat provides temperature-based feedback control by continuously monitoring the heating region and automatically interrupting power when the open latch threshold is reached. The system includes feedback through temperature sensing that enables automatic recovery when temperatures fall below the close latch threshold, creating a self-regulating safety mechanism

Inventive Principle:

Principle #23Feedback

2Object-affected harmful factors

If a thermal cutoff is used to prevent overheating, then temperature safety is improved, but the heating circuit becomes inoperative until the cutoff resets

Engineering Contradiction:

Improveoverheat protectionVSAvoidsystem operability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The latching thermostat introduces dynamic behavior with two distinct threshold levels (open latch and close latch thresholds). The system transitions between operational and protective states based on temperature conditions, enabling automatic recovery without manual intervention. This dynamic switching maintains system operability while providing robust overheat protection

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system utilizes parameter changes in temperature thresholds to control system state. By establishing different threshold values for opening and closing the circuit, the system adapts its operational parameters based on temperature conditions, allowing automatic recovery and maintaining reliability while preventing damage

Inventive Principle:

Principle #35Parameter changes

3Reliability

If redundant heating circuits are implemented, then system reliability is improved, but device complexity increases

Engineering Contradiction:

Improveheating system redundancyVSAvoidcircuit configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The redundant heating system is segmented into independent heating circuits, each with its own latching thermostat and temperature control. This segmentation allows individual circuit failure without affecting the entire system, maintaining reliability while using simple, modular components that reduce overall system complexity

Inventive Principle:

Principle #1Segmentation

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 robust overheat protection without rendering all heating circuits inoperative, ensuring continued operation and maintaining safe temperature ranges even after a stuck-on failure, thus preventing damage and ensuring system functionality.

Implementation Method 1

The latching thermostat is configured to consume power supplied by the temperature controller to the heating element in response to a temperature of the latching thermostat reaching an open latch threshold temperature

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

A thermistor is coupled in parallel with the temperature responsive latch. The thermistor is configured to dissipate power in the second state to maintain the temperature of the latching thermostat above the close latch threshold

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS11153935B2Latching thermostats for redundant heating

Publication Date: 2021.10.19 GOODRICH CORP

AI summary

Redundant heating systems include a plurality of heating circuits to heat a region. Heating circuits include a temperature sensor to sense a temperature of the region, a heating element, a temperature controller to provide power to the heating element based on the sensed temperature of the region, and a latching thermostat in series with the heating element. The latching thermostat consumes power supplied by the temperature controller to the heating element in response to a temperature of the latching thermostat reaching an open latch threshold temperature.