Hybrid Engine Oil Fuel Dilution Control During Cold Starts

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Solution Overview

Problem

Fuel dilution in engine oil of hybrid electric vehicles leads to decreased viscosity and degradation, causing increased component wear and reduced service intervals due to unburned fuel entering the oil during non-stoichiometric combustion conditions.

Innovation Solution

Implementing methods to detect catalyst and turbine temperatures, limiting engine torque during enrichment phases when temperatures exceed thresholds, inhibiting engine stops under certain conditions, and modifying torque requests to reduce fuel injection, thereby preventing fuel from entering the engine oil.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the engine operates during enrichment phase with lambda value less than 1, then the engine can meet high power demand, but fuel enters the engine oil causing decreased viscosity and degradation

Engineering Contradiction:

Improveengine power outputVSAvoidengine oil quality

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The system performs preliminary heating of the catalyst and turbine before allowing enrichment phase operation. By detecting that the catalyst temperature exceeds a first temperature threshold (e.g., 825-925°C) and turbine temperature exceeds a second temperature threshold (e.g., 725-825°C), the control unit authorizes enrichment phase operation, ensuring fuel evaporates before entering the oil system.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The catalyst and turbine act as intermediary thermal processing elements. The exhaust gases pass through the catalyst and turbine which are maintained at high temperatures, serving as a thermal barrier that evaporates fuel before it can contaminate the engine oil, thus protecting the oil system while allowing rich combustion.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of energy

If the engine is stopped frequently to save fuel, then energy consumption decreases, but fuel accumulates in the engine oil due to insufficient evaporation

Engineering Contradiction:

Improvefuel consumptionVSAvoidfuel in engine oil

Core Design Contradiction:

Loss of energyVSQuantity of substance

Solution Approach 1:

The control unit continuously monitors catalyst temperature and turbine temperature, and based on this feedback, dynamically controls engine operation. When temperatures are sufficient, the engine can stop to save fuel; when temperatures are low, the engine continues running to evaporate fuel, preventing oil contamination while optimizing fuel consumption.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system changes the operational parameters (temperature thresholds) that trigger engine stop/start decisions. By monitoring whether catalyst temperature exceeds the first threshold and turbine temperature exceeds the second threshold, the system dynamically adjusts engine operation to balance fuel savings with fuel evaporation requirements.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If the engine operates at low temperature, then fuel economy improves, but fuel dilution in engine oil increases

Engineering Contradiction:

Improvefuel efficiencyVSAvoidfuel dilution

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The system introduces a new dimensional criterion for engine operation decisions - not just based on fuel efficiency or power demand, but on the thermal state of the exhaust system (catalyst and turbine temperatures). This additional dimension allows the system to permit fuel-rich operation only when the exhaust system is hot enough to evaporate fuel, thereby achieving good fuel economy without fuel dilution.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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

Reduces fuel dilution in engine oil by minimizing fuel introduction and promoting evaporation, maintaining engine operation to prevent wear and extend service intervals.

Implementation Method 1

detecting one or more of a catalyst temperature and a turbine temperature

Methodology Applied

Scientific EffectTemperature detection:

Implementation Method 2

detecting a temperature of engine oil in the engine at the first engine start of the drive cycle

Methodology Applied

Scientific EffectTemperature detection:

Implementation Method 3

maintaining an engine in an on condition for a longer period to encourage the evaporation of fuel from the engine oil

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS12442320B2Method and apparatus for mitigating fuel in oil

Publication Date: 2025.10.14 JAGUAR LAND ROVER LTD

AI summary

A method (500) and apparatus (10-5) for carrying out the method of mitigating fuel in oil in an internal combustion engine of a hybrid electric vehicle, the method comprising: determining an amount of fuel flow into the engine oil during one or more cold start phases of engine operation (505); determining an amount of fuel flow into the engine oil during one or more enrichment phases of engine operation (510); determining an amount of fuel evaporated from the engine oil during one or more phases of vehicle operation with the engine on (515); determining an amount of fuel evaporated from the engine oil during one or more phases of vehicle operation with the engine off (520); determining a percentage of fuel in the engine oil from the amount of fuel flow into the engine oil and the amount of fuel evaporated from the engine oil (525); and modifying vehicle operation based on the percentage of fuel in the engine oil exceeding a first fuel in oil threshold or a second fuel in oil threshold (540).