Aircraft Engine Oil Particle Analysis for Coking Diagnosis

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Solution Overview

Problem

Existing methods for diagnosing engine conditions, such as coking in lubricating fluids, face challenges including lack of repeatability, inability to analyze particles larger than 5 µm, and failure to detect certain phenomena like oil coking.

Innovation Solution

A method involving obtaining a lubricating fluid sample, filtering to obtain particles, directing an excitation beam to detect energy levels, determining the level of coking by analyzing the difference in energy levels and the percentage of surface area covered by coking-related materials, and diagnosing the engine condition based on this analysis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If optical atomic spectroscopy is used for analyzing lubricant, then elemental analysis can be performed, but it cannot detect particles greater than 5 μm and lacks repeatability among different equipment

Engineering Contradiction:
Improveelemental analysis capabilityVSAvoidparticle size detection range
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent combines multiple analysis techniques (optical microscopy for particle imaging, Raman spectroscopy for chemical composition, and energy dispersive X-ray spectroscopy for elemental analysis) into a single integrated system. This merging allows the system to overcome the limitations of individual techniques, enabling detection of particles of all sizes while providing comprehensive characterization including chemical composition and elemental analysis.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The diagnostic system is designed to perform multiple functions: visualizing particles of any size, identifying chemical composition through Raman spectroscopy, analyzing elemental composition through X-ray spectroscopy, and detecting coking phenomena. This multi-functional approach replaces the need for multiple separate analysis instruments, achieving universality in lubricant diagnostics.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Quantity of substance

If optical atomic spectroscopy is used for total oil sample analysis, then elemental composition can be determined, but it cannot characterize individual particles

Engineering Contradiction:
Improveelemental compositionVSAvoidindividual particle characterization
Core Design Contradiction:
Quantity of substanceVSMeasurement precision

Solution Approach 1:

The system segments the analysis process into distinct stages: first capturing individual particle images through optical microscopy, then applying Raman spectroscopy to each particle for chemical composition, and finally using energy dispersive X-ray spectroscopy for elemental analysis. This segmentation allows characterization of individual particles while also providing overall lubricant composition data.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary step of filtering and isolating individual particles from the bulk lubricant sample before analysis. This intermediary process enables each particle to be analyzed separately while still contributing to the overall composition data, bridging the gap between individual particle characterization and bulk material analysis.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If conventional analysis methods are used, then general lubricant condition can be assessed, but they cannot detect coking phenomena

Engineering Contradiction:
Improvelubricant condition assessmentVSAvoidcoking detection capability
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The system utilizes Raman spectroscopy to detect characteristic spectral signatures of coked particles. Coking produces specific molecular structures that exhibit distinct Raman spectral patterns, allowing the system to identify and quantify coking phenomena based on these spectral 'color changes' or shifts in vibrational modes.

Inventive Principle:
Principle #32Color changes

Solution Approach 2:

The patent replaces conventional mechanical or chemical analysis methods with optical and spectroscopic techniques. By using Raman spectroscopy and energy dispersive X-ray spectroscopy, the system can non-invasively detect coking phenomena without requiring physical or chemical alteration of the sample, thereby enabling detection of phenomena that conventional methods cannot detect.

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

This method allows for accurate detection and diagnosis of engine coking conditions, enabling timely maintenance and improving engine efficiency by providing a detailed analysis of particle composition and energy levels.

Implementation Method 1

The analysis of engine oil or other lubricant for the purpose of identifying premature component wearing has been performed for several decades using optical atomic spectroscopy (e.g., atomic emission spectroscopy (AES), as well as atomic absorption spectroscopy (AAS))

Methodology Applied
Scientific EffectOptical atomic spectroscopy: Absorption Spectroscopy

Implementation Method 2

optical atomic spectroscopy (e.g., atomic emission spectroscopy (AES), as well as atomic absorption spectroscopy (AAS))

Methodology Applied
Scientific EffectAtomic emission spectroscopy: Absorption Spectroscopy

Implementation Method 3

directing energy dispersive x-rays

Methodology Applied
Scientific EffectEnergy dispersive x-ray detection: X-Ray

Data Source

PatentEP3751120B1System and method for diagnosing a condition of an engine
Publication Date: 2025.05.21 PRATT & WHITNEY CANADA CORP
  • EP3751120B1 patent drawingFigure 1
  • EP3751120B1 patent drawingFigure 2
  • EP3751120B1 patent drawingFigure 3A

AI summary

A method (300) for diagnosing a condition of an aircraft engine (10) comprises obtaining a sample of lubricating fluid (126) from the engine (10), filtering the sample (126) to obtain a plurality of particles (124) from the lubricating fluid, directing an excitation beam towards the particles (124), detecting an energy level (Qm) emitted from the particles (124) in response to the excitation beam, determining a level of coking in the lubricating fluid based on a difference between the energy level as detected (Qm) and an expected energy level (Qe), and diagnosing a condition of the engine (10) based on the level of coking in the lubricating fluid.