Lean Idle Operation Reduces Engine Particle Emissions
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Solution Overview
Problem
Internal combustion engines, particularly gas engines, experience high emissions of fine dust particles during idling due to oil accumulation in the combustion chamber, which is exacerbated by reverse blow-by and insufficient oxygen, leading to increased particle emissions when load is applied.
Innovation Solution
Switching to lean operation during idling reduces the pressure difference between the crankcase and combustion chamber, minimizing oil entry and using adaptive lambda control, advanced ignition systems, and quick transitions to stoichiometric operation to manage emissions and load changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the engine operates in stoichiometric operation during idling, then the combustion process maintains normal pressure differential, but oil accumulates in the combustion chamber leading to high particle emissions
Solution Approach 1:
The patent changes the operational parameter from stoichiometric to lean operation during idling. This parameter change modifies the combustion characteristics to reduce oil accumulation in the combustion chamber, thereby lowering particle emissions while maintaining reliable operation through controlled air-fuel ratio adjustment
2Loss of energy
If the throttle valve is closed during idling to reduce air intake, then fuel consumption is reduced, but vacuum is created in the intake manifold causing reverse blow-by and oil entry into combustion chamber
Solution Approach 1:
The patent changes the air-fuel ratio parameter to lean operation during idling, which allows the throttle valve to remain slightly more open. This prevents vacuum formation in the intake manifold and eliminates reverse blow-by, thereby preventing oil entry into the combustion chamber while maintaining acceptable fuel economy
3Object-generated harmful factors
If lean operation is used during idling to reduce particle emissions, then oil accumulation is minimized, but air requirement increases significantly
Solution Approach 1:
The patent implements lean operation by adjusting the air-fuel ratio parameter, which increases air intake requirements. This is achieved by opening the throttle element wider during lean-burn operation, allowing sufficient air to enter the combustion chamber to prevent oil accumulation while managing the increased air requirement through controlled throttle positioning
4Quantity of substance
If the throttle element is opened wider in lean-burn operation to increase air intake, then pressure in intake manifold increases, but this must be coordinated with lambda control to maintain emissions compliance
Solution Approach 1:
The patent employs feedback control through lambda control to coordinate the throttle element positioning with air-fuel ratio management. The system continuously monitors and adjusts the lambda value to ensure emissions compliance while maintaining the desired air intake for lean operation, reducing the complexity of manual coordination
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 significantly reduces particle emissions, maintains low NOx emissions, and allows for compliance with stringent EURO VI emission regulations by optimizing lambda control and ignition strategies, while also improving fuel efficiency.
Implementation Method 1
switches to lean operation when idling and is operated in lean operation, so that preferably a vacuum is generated in the crankcase and/or the pressure difference between the crankcase and the combustion chamber can be reduced
Implementation Method 2
Due to the combustion process in the Otto engine, a throttle valve, via which charge air can be fed from an intercooler to a combustion chamber, is closed except for a small gap when idling. A vacuum is created in the intake manifold compared to the environment.
Implementation Method 3
If the load increases after a long period of idling, the accumulated oil is burned off within a short period of time by the increased flame intensity
Data Source
Figure 1
AI summary
The invention relates to an operating method for a device (V) comprising an internal combustion engine capable of operating in lean and stoichiometric modes, a crankcase (1), at least one combustion chamber (4) and preferably a throttle element (11) through which charge air from an intercooler can be supplied to the combustion chamber (4), wherein the internal combustion engine is switched to lean operation at idle and operated in lean mode, so that in particular the pressure difference between the crankcase (1) and the combustion chamber (4) is reduced.