Internal Combustion Engine Fuel Evaporation Management
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Solution Overview
Problem
Internal combustion engines operating in flex-fuel mode with ethanol-rich fuels face challenges in managing fuel evaporation from engine oil, leading to rich fuel mixtures and increased exhaust emissions, particularly during cold starts and low-load conditions.
Innovation Solution
The method involves detecting a low air-fuel ratio and transitioning to an operating state with higher fuel consumption by increasing fuel injection, potentially through retarded ignition timing and divided injection events, to combust fuel ingressed into the engine oil, thereby reducing exhaust emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the air-fuel mixture is enriched to account for fuel evaporation from engine oil, then exhaust gas emissions (hydrocarbons and carbon monoxide) increase, but if the mixture is kept lean, then fuel evaporation from engine oil cannot be combusted efficiently
Solution Approach 1:
The invention dynamically adjusts the air-fuel mixture composition based on real-time detection of fuel evaporation from engine oil. The control system monitors the amount of evaporated fuel and continuously enriches or leans the air-fuel mixture accordingly, allowing the system to adapt to varying operating conditions and temperature profiles, thus optimizing both emission control and fuel efficiency
Solution Approach 2:
The invention implements a closed-loop feedback control system that detects the actual fuel evaporation from engine oil and uses this information to adjust the air-fuel mixture. The control unit receives feedback on the evaporated fuel amount and modifies the injection strategy or air intake accordingly, ensuring that the air-fuel ratio is continuously optimized to combust evaporated fuel while minimizing harmful emissions
2Reliability
If more fuel is injected during cold starting with ethanol, then fuel ingress into engine oil increases, but if less fuel is injected, then cold starting performance deteriorates
Solution Approach 1:
The invention performs preliminary detection of fuel evaporation from engine oil during the cold start phase and pre-adjusts the air-fuel mixture composition before the evaporation problem becomes severe. By anticipating the fuel ingress issue and preparing the combustion system in advance, the system can handle the evaporated fuel effectively without compromising cold starting performance
Solution Approach 2:
The invention changes the air-fuel ratio parameter dynamically during cold start based on detected fuel evaporation levels. When fuel evaporation is detected, the system enriches the mixture temporarily to ensure complete combustion of the additional fuel, then gradually leans the mixture as the engine warms up and evaporation decreases, optimizing both starting reliability and emission 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 allows for efficient combustion of fuel ingressed into the engine oil, maintaining torque and reducing hydrocarbon and carbon monoxide emissions without compromising driving comfort or exceeding component temperature limits.
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 by way of the intake manifold
Implementation Method 2
when cold starting with ethanol and during the subsequent warm-up phase, considerably more fuel is wiped from the cylinder walls into the engine oil by the piston rings
Implementation Method 3
this fuel evaporates and is added via the crankcase ventilation system to the fresh air supply provided to the engine by way of the intake manifold
Implementation Method 4
the fuel, which exited the engine oil into the intake air of the internal combustion engine, can be combusted
Data Source
AI summary
The invention deals with a method for operating an internal combustion engine with engine oil as the lubricant and a fuel supply by means of direct injection, wherein an air number (lambda) of a fuel-air mixture supplied to the internal combustion engine is determined. Provision is made in the method according to the invention for the internal combustion engine to be transferred to an operating state with higher fuel consumption, when a low air number (lambda) is detected in driving conditions with a high percentage of fuel ingress from a crankcase ventilation system into the fuel-air mixture. By means of this increase in the fuel requirement, the fuel, which exited the engine oil into the intake air of the internal combustion engine, can be combusted; and an increase in the exhaust gas emissions by means of incompletely combusted fuel, in which typically hydrocarbons and carbon dioxide arise, can be avoided. In a warm-up phase of the internal combustion engine, the fuel, which ingressed into the engine oil, can thus likewise be combusted, even if under certain temperature-time conditions, particularly in the partial load operating mode and during idling, more fuel is present in the fuel-air mixture than is actually required for operating the internal combustion engine.