Fuel Outgassing Compensation in Engine Oil via Lambda Feedback
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Solution Overview
Problem
Internal combustion engines, especially those operating in flex-fuel mode with ethanol and gasoline mixtures, face challenges in accurately accounting for fuel outgassing from engine oil, leading to drivability issues due to mixture deviations, which existing methods partially address with insufficient accuracy and potential aftereffects.
Innovation Solution
A method that uses a mass flow offset determined from deviations in the fuel/air ratio to adjust fuel metering, incorporating a map-based pilot control and integrating the outgassing model to balance lambda controller deviations, allowing for quicker corrections and preventing aftereffects by dynamically adapting to fuel mass flow and air flow changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a map-based pilot control is used to account for fuel outgassing, then the fuel/air mixture control is improved, but control accuracy is insufficient under all operating conditions
Solution Approach 1:
The patent implements a feedback mechanism by determining a mass flow offset from the deviation of the actual fuel/air ratio from its nominal value and using this offset to correct the fuel metering. The lambda controller continuously monitors the exhaust gas composition and feeds this information back to adjust the fuel injection, thereby improving control accuracy under all operating conditions while maintaining reliable fuel/air mixture control.
2Reliability
If the lambda controller is decontrolled to account for evaporated fuel, then the outgassing is taken into account, but drivability problems occur during dynamic operation
Solution Approach 1:
The patent applies dynamics by making the fuel metering correction variable and adaptive rather than fixed. The mass flow offset is dynamically determined based on real-time deviations in the fuel/air ratio and operating conditions, allowing the system to smoothly adapt to changing engine loads and rotational speeds. This dynamic approach maintains drivability during transient operations while effectively compensating for fuel outgassing.
3Reliability
If a characteristic diagram is used to determine expected outgassing quantity, then the outgassing is accounted for, but deviations remain and require further correction
Solution Approach 1:
The patent uses feedback by continuously monitoring the actual fuel/air ratio deviation from its nominal value and using this information to determine a mass flow offset. This offset is then applied to correct the fuel metering, closing the control loop. The characteristic diagram provides an initial estimate, but the feedback mechanism based on lambda sensor data ensures that any remaining deviations are compensated, achieving accurate mixture composition control.
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 effectively compensates for mixture deviations caused by different boiling curves, ensuring accurate fuel/air mixture control across various operating conditions, reducing the risk of control fluctuations and preventing adaptation forgetting, while accurately accounting for fuel outgassing, especially during cold starts and warm-up phases.
Implementation Method 1
When the temperature of the engine oil increases, this fuel evaporates and is added via the crankcase ventilation system to the fresh air supply provided to the engine
Data Source
AI summary
The invention deals with a method for operating an internal combustion engine with engine oil as the lubricant, wherein a fuel mass flow outgassing from the engine oil is ascertained and is taken into account via a map-based pilot control during the metering of a quantity of fuel supplied to the internal combustion engine and wherein a fuel/air ratio supplied to the internal combustion engine is determined. Provision is made in the method according to the invention for a mass flow offset determined from the deviation of the fuel/air ratio supplied to the internal combustion engine from a nominal value to be taken into account when the metering of the quantity of fuel supplied to the internal combustion engine occurs during an effective duration of the map-based pilot control. The mass flow offset takes the deviation into account, which remained after the correction by a map-based pilot control of the quantity of fuel metered, on the basis of the modeled outgassing of fuel from the engine oil, and said mass flow offset balances the lambda controller in this way. The mass flow offset can by way of example have the effect of shortening the duration injection. The mixture deviations as a result of different boiling curves of the components of the fuel blend, which cannot be completely taken into account by the map-based pilot control under all operating conditions of the internal combustion engine, can in this way be compensated.