Cold Start Particle Emission Reduction via Cylinder Air Pumping
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Solution Overview
Problem
Internal combustion engines, particularly Otto engines, face high particle emissions during cold starts due to incomplete combustion, low mixture homogenization, and cold combustion chamber walls, leading to soot formation and increased emissions of carbon monoxide and unburned hydrocarbons, which are challenging to manage with existing methods.
Innovation Solution
A method that determines combustion chamber and ambient temperatures to compress and warm the air in the combustion chambers without fuel injection until a defined temperature is reached, then switches on fuel injection, using the engine as an 'air pump' to preheat the chamber walls, reducing soot formation by improving fuel evaporation and mixture homogenization, and optionally increasing injection pressure for better atomization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fuel injection is performed during cold start, then the engine can start and operate, but soot formation increases due to cold combustion chamber walls and incomplete combustion
Solution Approach 1:
The method performs preliminary heating of the combustion chamber walls by operating the engine without fuel injection for a defined number of crankshaft revolutions during cold start. This preliminary action raises the wall temperature before fuel injection begins, preventing the cold wall issues that cause incomplete combustion and soot formation, thereby resolving the contradiction between enabling engine operation and reducing harmful emissions.
2Reliability
If the engine operates with rich combustion air ratio during cold start, then combustion stability is improved, but particle emissions increase
Solution Approach 1:
The method applies preliminary heating of the combustion chamber walls before introducing fuel, which improves fuel evaporation and mixture homogenization. This allows the engine to operate with leaner combustion air ratios during cold start while maintaining combustion stability, thereby reducing particle emissions without sacrificing reliability.
3Object-generated harmful factors
If additional measures are taken to increase exhaust temperature for particle filter regeneration, then soot oxidation is improved, but device complexity increases
Solution Approach 1:
The method enables the exhaust system to serve itself by producing high-temperature exhaust gases through controlled lean combustion and cylinder deactivation strategies. The engine's own combustion process generates sufficient heat for particle filter regeneration without requiring external heating devices or complex additional components, thus improving soot oxidation while avoiding increased device complexity.
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 method effectively reduces soot emissions during cold starts by preheating the combustion chamber walls, allowing for lower fuel enrichment and improved mixture homogenization, thereby reducing particle emissions without requiring additional hardware, making it a cost-effective solution for both gasoline and diesel engines.
Implementation Method 1
dragging the internal combustion engine by a starter when the combustion chamber temperature is below a first threshold temperature and the ambient temperature is below a second threshold temperature, the air in the combustion chambers being compressed and warming up
Implementation Method 2
the air in the combustion chambers being compressed and warming up
Implementation Method 3
improving fuel evaporation and mixture homogenization
Data Source
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AI summary
The invention relates to a method for reducing the particulate emissions of an internal combustion engine (10) during a cold start. The combustion chamber temperature (TBR) and the ambient temperature (TUMG) are determined. If the combustion chamber temperature (TBR) is below a first threshold temperature (TS1) and the ambient temperature (TUMG) is below a second threshold temperature (TS2), a cold start condition is detected. In this case, the internal combustion engine (10) is pulled by the starter, whereby the air in the combustion chambers (12) is compressed and heated. This heat is dissipated to the combustion chamber walls (12), which also heat up. In this operating situation, no fuel injection takes place in the combustion chambers (12) and no ignition occurs, so that no combustion takes place in the combustion chambers (12) and the internal combustion engine (10) merely compresses fresh air.The compression work heats up the combustion chambers (12), resulting in better vaporization of the fuel (56) in the combustion chamber (12). It is provided that a fuel injection system, initially deactivated, is activated in the combustion chambers (12) when the combustion chamber walls (14) have reached a sufficient temperature, thus reducing soot formation caused by unburned fuel coming into contact with the cold combustion chamber walls (14).