Engine Oil Dilution Estimation via Fuel and Carbon Fractionation

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Solution Overview

Problem

Current methods for estimating the overall dilution of engine oil in internal combustion engines equipped with exhaust gas treatment devices fail to accurately account for the dilution of fuel and the fractionation of carbon chains, leading to incorrect oil change intervals and potential engine reliability issues.

Innovation Solution

A method that estimates the overall dilution rate by combining the dilution rate of fuel and the fractionation of carbon chains in the engine oil, using a kinetic law of order 1 to model the variation of dilution due to fuel introduction, and incorporating a function linking dilution rate by fractionation to the rate of fuel introduced, which is bounded by engine operation modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If fuel post-injection is used for pollutant treatment, then emission treatment effectiveness is improved, but fuel dilution in engine oil increases

Engineering Contradiction:
Improvepollutant emissionVSAvoidfuel dilution in oil
Core Design Contradiction:
Object-generated harmful factorsVSLoss of substance

Solution Approach 1:

The system continuously monitors fuel dilution levels in engine oil and uses this feedback to dynamically adjust the post-injection fuel treatment strategy. When dilution approaches critical thresholds, the system modifies regeneration timing or intensity to prevent excessive dilution while maintaining emission control effectiveness.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The invention changes operational parameters of the post-injection system based on engine oil condition. By adjusting fuel injection timing, duration, or quantity during regeneration phases, the system optimizes the balance between pollutant treatment and fuel dilution prevention, adapting to varying engine operating conditions and oil states.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If oil change interval is extended to reduce maintenance costs, then economic efficiency is improved, but engine reliability deteriorates due to inaccurate dilution estimation

Engineering Contradiction:
Improvemaintenance efficiencyVSAvoidengine reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The invention replaces traditional mechanical/time-based oil change schedules with a model-based estimation system. Using mathematical models that predict fuel dilution and oil degradation, the system determines optimal oil change intervals dynamically, replacing oil based on actual condition rather than fixed time intervals, thereby extending intervals safely and improving maintenance efficiency.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system performs preliminary estimation of oil dilution and degradation trends before critical thresholds are reached. By predicting future oil quality based on current degradation rates and operating conditions, the system proactively schedules oil changes at optimal moments, preventing reliability issues while maximizing interval length.

Inventive Principle:
Principle #10Preliminary action

3Device complexity

If traditional fuel dilution modeling is used, then estimation simplicity is maintained, but measurement precision deteriorates due to unaccounted carbon chain fractionation

Engineering Contradiction:
Improvemodel complexityVSAvoiddilution estimation accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The invention segments the oil degradation process into distinct components: fuel dilution effects and carbon chain fractionation effects. By separating these mechanisms and modeling them independently with appropriate mathematical relationships, the system achieves comprehensive accuracy without excessive complexity, as each segment can be modeled with targeted simplicity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention creates a composite estimation model that combines fuel dilution modeling with carbon chain fractionation modeling. This composite approach integrates multiple degradation mechanisms into a unified framework, achieving high measurement precision by accounting for both phenomena simultaneously while maintaining reasonable complexity through modular structure.

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

This approach provides a more accurate estimation of engine oil dilution, ensuring timely oil changes and maintaining engine reliability while reducing unnecessary maintenance costs, and aligns with evolving pollutant emission standards.

Implementation Method 1

Evaporation refers to the vaporization of fuel into the gases surrounding the engine oil pool

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 2

the dilution of the oil by fractional cracking of some of its carbon chain compounds

Methodology Applied
Scientific EffectFractionation: Fractionation

Data Source

PatentEP3902990B1Method for estimating the overall dilution of the oil of an internal combustion engine
Publication Date: 2022.12.07 RENAULT SA
  • EP3902990B1 patent drawingFigure 1~2
  • EP3902990B1 patent drawingFigure 3
  • EP3902990B1 patent drawingFigure 4

AI summary

The invention relates to a method for estimating the overall dilution ratio of the oil of an internal combustion engine provided with a device for treating combustion gases requiring phases of treatment by post-injection of fuel into the cylinders of the engine, said method comprising steps of estimating the dilution ratio of fuel in oil (T1), characterised in that it also comprises at least one step of estimating the dilution ratio of the oil's own carbonaceous compound fractionation (T2) as a function of the ratio of fuel injected into the oil (T11), the overall dilution ratio (T) of the oil being the sum of at least said ratio of fuel dilution in oil (T1) and said dilution ratio of the oil fractionation.