Hybrid Engine Torque Limiting for Fuel-in-Oil Mitigation
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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 a method to detect catalyst and turbine temperatures, limiting engine torque below a threshold when these exceed certain temperatures to prevent excess fuel from entering the oil, and maintaining engine operation until temperatures decrease to a lower threshold, allowing torque increase when safe to do so, along with inhibiting engine stops under specific conditions to enhance fuel evaporation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine operates in enrichment phase (lambda < 1) to meet power demand, then power output is improved, but fuel enters the engine oil causing degradation and increased wear
Solution Approach 1:
The system performs preliminary action by detecting catalyst and turbine temperatures and proactively limiting engine torque before fuel dilution occurs. When temperatures exceed the first threshold, the control system restricts engine operation to prevent enrichment phase operation, thereby preventing fuel from entering the oil before degradation can occur.
Solution Approach 2:
The system implements feedback by continuously monitoring catalyst and turbine temperatures and using this information to dynamically adjust engine torque limits. The control system compares detected temperatures against thresholds and automatically modifies engine operation parameters to maintain oil quality while allowing power operation when conditions are favorable.
2Loss of energy
If the engine is stopped frequently to improve fuel economy, then energy efficiency is improved, but fuel accumulates in the engine oil when the engine restarts
Solution Approach 1:
The system uses feedback from temperature sensors to determine when to allow engine stops and when to maintain operation. By monitoring catalyst and turbine temperatures, the control system decides whether to permit engine shutdown for fuel economy or maintain operation to prevent fuel accumulation, dynamically adjusting based on real-time conditions.
Solution Approach 2:
The system changes operational parameters by adjusting engine torque limits and stop/start permissions based on temperature conditions. When temperatures are below thresholds, the system allows normal stop/start operation for fuel economy; when temperatures exceed thresholds, it modifies parameters to prevent enrichment operation that would cause fuel dilution.
3Reliability
If engine torque is limited to prevent fuel in oil, then oil quality is maintained, but vehicle performance and power delivery are reduced
Solution Approach 1:
The system applies dynamics by making torque limits variable rather than fixed. Engine torque restrictions are dynamically adjusted based on real-time catalyst and turbine temperature conditions, allowing full performance when temperatures are favorable and applying limits only when necessary to prevent fuel dilution, thereby optimizing both protection and performance.
Solution Approach 2:
The system changes operational parameters dynamically based on temperature conditions. Rather than imposing constant torque limits, the control system adjusts engine operation parameters in real-time, allowing enrichment phase operation and full power delivery when catalyst and turbine temperatures are below thresholds, and applying restrictions only when temperatures indicate risk of fuel dilution.
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 introduction into the engine oil, preventing degradation and maintaining engine health by ensuring fuel evaporation, thus extending service intervals and minimizing wear.
Implementation Method 1
detecting one or more of a catalyst temperature and a turbine temperature
Implementation Method 2
detecting a temperature of engine oil in the engine
Implementation Method 3
maintaining an engine in an on condition for a longer period to encourage the evaporation of fuel from the engine oil
Data Source
AI summary
A method (100) and apparatus (10-1) for carrying out the method of mitigating fuel in oil in an internal combustion engine of a hybrid electric vehicle, the method comprising: detecting one or more of a catalyst temperature and a turbine temperature (110); and when the one or more of the catalyst temperature and the turbine temperature exceeds a first temperature threshold, limiting engine torque below a threshold engine torque required for the operation of an enrichment phase of engine operation (120), wherein the enrichment phase of engine operation provides a lambda value less than 1.