Aircraft Blade Ice Protection with Isolated Temperature Sensing

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Solution Overview

Problem

Conventional ice protection systems for rotary blades in aircraft often rely on indirect temperature measurement, which can lead to potential damage to the aircraft structure due to overheating, and lack advanced fault detection and isolation capabilities.

Innovation Solution

A rotary blade system featuring a temperature sensing circuit directly connected to the blade body, allowing for independent measurement of actual temperature and enabling precise control of heater elements to prevent overheating, along with a control module that compares actual temperatures to thresholds and provides malfunction indications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional indirect temperature measurement methods are used, then the system structure is simpler, but the measurement precision is insufficient leading to potential overheating and structural damage

Engineering Contradiction:

Improvetemperature measurement accuracyVSAvoidsystem structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

A temperature sensing circuit is introduced as an intermediary component between the heater element and the control system. This circuit includes a temperature sensor (such as a thermocouple or RTD) that directly contacts the blade structure to sense actual temperature, and an isolation circuit that electrically isolates the sensing circuit from the heater circuit while transmitting temperature signals to the controller for accurate temperature measurement and control.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If heater elements are operated to raise temperature above ice accretion threshold, then ice protection effectiveness is improved, but the risk of structural damage from overheating increases

Engineering Contradiction:

Improveice protection effectivenessVSAvoidoverheating damage risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system implements a feedback control mechanism where the temperature sensing circuit continuously monitors the actual temperature of the blade structure and feeds this information back to the controller. The controller compares the sensed temperature with predetermined threshold values (first threshold for ice accretion prevention, second threshold for damage prevention) and automatically adjusts heater element operation accordingly, turning off heating when the second threshold is approached to prevent structural damage.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The control system is designed with predetermined temperature thresholds that act as safety margins before damage occurs. The first threshold provides a buffer zone for effective ice protection, while the second threshold establishes a safety cushion to prevent overheating damage. This beforehand cushioning approach ensures that the blade temperature remains within safe operating limits even during prolonged heating operations.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Device complexity

If temperature sensing circuit is integrated with heater elements, then the device complexity is reduced, but fault detection and isolation capabilities are lost

Engineering Contradiction:

Improvecircuit integration levelVSAvoidfault detection capability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The system is segmented into distinct functional circuits: a heater element circuit for heating, a temperature sensing circuit for measurement, and a control circuit for coordination. The temperature sensing circuit includes separate signal leads that are electrically isolated from the heater element leads, allowing independent operation and fault isolation. This segmentation enables the system to detect and identify failures in individual circuits without affecting the entire system.

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 enhances the safety and reliability of ice protection systems by directly measuring blade temperatures, reducing the risk of structural damage and enabling continuous operation despite potential malfunctions, while maintaining efficient ice accretion control.

Implementation Method 1

The temperature sensing circuit is in thermal communication with the blade body and is electrically isolated from the one or more heater elements for determining actual temperature of the rotary blade independent of operation of the one or more heater elements

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

one or more heater elements connected to the blade body

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS10543926B2Ice protection systems

Publication Date: 2020.01.28 SIKORSKY AIRCRAFT CORP

AI summary

A rotary blade includes a blade body, one or more heater elements, and a temperature sensing circuit. The one or more heater elements are connected to the blade body. The temperature sensing circuit is in thermal communication with the blade body and is electrically isolated from the one or more heater elements for determining actual temperature of the rotary blade independent of operation of the one or more heater elements.