Hybrid Engine Stop Control to Mitigate Fuel Dilution in Oil
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Solution Overview
Problem
Fuel dilution in engine oil of hybrid electric vehicles occurs due to non-stoichiometric combustion, leading to decreased viscosity and degradation, which increases component wear and reduces service intervals.
Innovation Solution
Implementing methods to detect catalyst and turbine temperatures, limiting engine torque during enrichment phases, inhibiting engine stops under certain conditions, and modifying torque requests to minimize fuel introduction and enhance evaporation from the engine oil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine operates under non-stoichiometric fuel-to-air ratio conditions, then power output is improved, but fuel transfers into engine oil causing degradation and increased component wear
Solution Approach 1:
The system performs preliminary detection of catalyst and turbine temperatures to predict fuel dilution risk before it occurs. Based on these temperature readings, the control system proactively limits engine torque to prevent enrichment phase operation that would cause fuel to transfer into the oil, thereby preventing oil degradation before it happens.
Solution Approach 2:
The system continuously monitors catalyst temperature and turbine temperature as feedback parameters. When these temperatures exceed predetermined thresholds, the system adjusts engine torque limits in real-time to prevent fuel dilution, creating a closed-loop control system that balances power output with oil quality protection.
2Use of energy by moving object
If the engine is stopped frequently to save fuel, then energy consumption is reduced, but fuel accumulates in engine oil when the engine restarts
Solution Approach 1:
Before allowing engine stop events, the system checks catalyst and turbine temperatures to determine if fuel dilution risk exists. When temperatures indicate potential fuel accumulation, the system preemptively prevents engine shutdown, ensuring the engine remains running long enough to evaporate fuel from the oil before stopping.
Solution Approach 2:
The system uses temperature feedback from catalyst and turbine sensors to dynamically control engine shutdown decisions. When temperatures are within safe ranges, normal stop/start operation is permitted; when temperatures exceed thresholds, the system adjusts shutdown timing to prevent fuel accumulation in the oil.
3Reliability
If engine torque is limited to prevent fuel in oil, then oil degradation is reduced, but vehicle performance and productivity decrease
Solution Approach 1:
The system dynamically adjusts torque limits based on real-time temperature conditions rather than applying fixed restrictions. When catalyst and turbine temperatures are within safe ranges, full torque is available; when temperatures exceed thresholds, torque limits are temporarily applied only during enrichment phases, creating a dynamic balance between protection and performance.
Solution Approach 2:
The system changes operational parameters (torque limits) based on temperature parameter thresholds. By monitoring catalyst and turbine temperatures and adjusting torque accordingly, the system modifies engine operation parameters to prevent fuel dilution only when necessary, maintaining optimal performance during normal operation.
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 engine oil, prevents degradation, and maintains engine operation to facilitate fuel evaporation, thereby extending service intervals and ensuring reliable vehicle performance.
Implementation Method 1
detecting one or more of a catalyst temperature and a turbine temperature
Implementation Method 2
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 (200) and apparatus 10-2 for carrying out the method of mitigating fuel in oil in an internal combustion engine of a hybrid electric vehicle, the method comprising: detecting a first engine start of a drive cycle when the vehicle speed is greater than zero (210); detecting a temperature of engine oil in the engine at the first engine start of the drive cycle (220); determining if the temperature of the engine oil is below an engine oil temperature threshold (230); when the temperature of the engine oil is determined to be below the engine oil temperature threshold, inhibiting an engine stop for a first predetermined time period unless the vehicle speed reaches zero (240).