Fuel Outgassing Detection in Engine Control Units
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Solution Overview
Problem
Conventional methods for checking outgassing of fuel from engine oil in internal combustion engines lead to incorrect fault diagnoses, particularly in short-term operation, due to uncombusted fuel evaporating and enriching the fuel/air mixture, which is misinterpreted as a defect.
Innovation Solution
A two-stage method using a theoretical model to estimate fuel outgassing based on operating parameters, with interventions such as closing the tank venting valve or entering a no-load phase to accurately detect outgassing, and adjusting the operating state to prevent incorrect fault diagnoses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods monitor fuel outgassing by detecting mass flow from crankcase to intake section, then fuel outgassing can be detected, but incorrect fault diagnoses are made during short-term operation due to uncombusted fuel evaporation
Solution Approach 1:
The control unit performs preliminary actions by closing the tank venting valve and entering a no-load phase before conducting fuel outgassing detection. This prepares the system in advance to eliminate interfering factors (external fuel vapor entry and normal operational fuel consumption) so that subsequent measurement of mass flow from crankcase to intake section accurately reflects only fuel outgassing from the lubricant, preventing incorrect fault diagnoses during short-term operation
Solution Approach 2:
The invention extracts and eliminates interfering factors from the measurement system by closing the tank venting valve to prevent external fuel vapor entry and by entering a no-load phase to eliminate normal fuel consumption. This isolation allows the mass flow measurement to exclusively detect fuel outgassing from the lubricant, improving both measurement precision and fault diagnosis reliability
2Measurement precision
If the tank venting valve is closed to prevent external fuel vapor entry, then measurement accuracy improves, but engine operation is interrupted
Solution Approach 1:
The control unit implements periodic action by temporarily closing the tank venting valve and entering a no-load phase only during the fuel outgassing detection period, then resuming normal operation. This time-limited intervention maintains measurement precision during the detection window while preserving engine productivity during normal operational periods, balancing accuracy requirements with operational continuity
3Measurement precision
If a no-load phase is entered to eliminate normal fuel consumption, then fuel outgassing detection accuracy improves, but operational time is consumed
Solution Approach 1:
The invention applies partial action by limiting the no-load phase to only the minimum necessary duration required for accurate fuel outgassing detection. The control unit enters the no-load phase temporarily, performs the mass flow measurement to detect fuel outgassing, then quickly returns to normal operation. This minimized-time intervention achieves measurement precision while reducing the loss of operational time to the extent possible
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 allows for reliable identification of fuel outgassing with reduced operational expenditure, minimizing incorrect fault diagnoses and ensuring accurate engine operation over extended periods.
Implementation Method 1
A mass flow from the crankcase to the intake section, which mass flow is dependent on the operating state of the internal combustion engine, is established on account of a pressure drop from the crankcase to the intake section
Implementation Method 2
Fuel which evaporates from the lubricant and is routed into the intake section via the crankcase venting system enriches the fuel/air mixture in the combustion chamber
Implementation Method 3
the intervention involves making a request for a no-load phase during a stop in a start/stop function
Data Source
AI summary
A control unit and a method for checking the outgassing of fuel from the lubricant of an internal combustion engine are provided, wherein, in a first method step, the outgassing of fuel from the lubricant is estimated on the basis of at least one operating parameter using a theoretical model during the normal operation of the internal combustion engine, and wherein, after the estimation of defined outgassing of fuel on the basis of the model, the outgassing of fuel is estimated in a second method step on the basis of at least one further operating parameter during a defined operating state.