Particulate Filter Regeneration via Engine Inertia Oxygen
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Solution Overview
Problem
Current methods for regenerating particulate filters in internal combustion engine exhaust systems often lead to increased nitrogen oxide emissions due to the need for a lean air-fuel ratio, which complicates the regeneration process and requires additional components like secondary air systems, increasing costs and emissions.
Innovation Solution
A method that regenerates the particulate filter by switching off fuel injection and utilizing residual oxygen in the exhaust system when the engine is winding down, allowing for oxidation of soot without shifting to a lean mixture, thus maintaining a stoichiometric air-fuel ratio and avoiding additional emissions, using the engine's inertia to increase oxygen availability and control the regeneration process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the air-fuel ratio is shifted towards a lean mixture to provide oxygen for particulate filter regeneration, then the temperature and oxygen availability for soot oxidation are improved, but the nitrogen oxide emissions increase significantly
Solution Approach 1:
The patent applies preliminary action by pre-heating the exhaust gas before the particulate filter using a heating element or by utilizing hot exhaust gas from a previous cycle. This ensures that when regeneration occurs, the temperature is already sufficient for soot oxidation without requiring a lean air-fuel ratio shift, thereby avoiding increased NOx emissions.
Solution Approach 2:
The patent introduces an intermediary substance, typically a chemical additive or catalytic agent, that facilitates soot oxidation at lower temperatures. This intermediary enables regeneration to proceed without raising the exhaust gas temperature through lean operation, thus preventing the formation of excessive nitrogen oxide emissions.
2Quantity of substance
If secondary air is blown into the exhaust system to enable regeneration, then oxygen availability for soot oxidation is improved, but the device complexity and cost increase
Solution Approach 1:
The patent applies self-service by utilizing the engine's own exhaust gas recirculation system or by redirecting a portion of the exhaust flow to provide the necessary oxygen for regeneration. This eliminates the need for a separate secondary air injection system, reducing device complexity while maintaining sufficient oxygen availability for soot oxidation.
Solution Approach 2:
The patent makes an existing exhaust system component multi-functional by enabling it to serve both as a normal exhaust pathway and as an oxygen source for regeneration. For example, the exhaust gas recirculation system is utilized to provide oxygen-rich gas to the particulate filter, combining two functions into one system and avoiding additional complexity.
3Temperature
If the advance angle is shifted in the late direction to raise temperature for regeneration, then the temperature for soot oxidation is improved, but the nitrogen oxide emissions increase and driving comfort is affected
Solution Approach 1:
The patent applies preliminary action by pre-heating the exhaust gas or the particulate filter before regeneration is initiated. This can be done using an electric heating element integrated into the filter housing or by utilizing hot exhaust gas from a previous operating cycle. By preparing the temperature in advance, the system avoids the need for late advance angle shifts during regeneration, thereby preventing increased NOx emissions.
Solution Approach 2:
The patent changes the temperature parameter through alternative means rather than adjusting the combustion timing. Specifically, it uses external heating sources or thermal energy storage materials that can raise the exhaust gas temperature or particulate filter temperature independently of the engine's combustion parameters, thus decoupling temperature control from advance angle adjustments and avoiding NOx formation.
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 emission-neutral particulate filter regeneration without a secondary air system, reducing nitrogen oxide emissions and enabling continuous catalytic converter functionality, with fewer regeneration steps and no need for additional after-treatment measures, ensuring efficient exhaust gas cleaning.
Implementation Method 1
the particulate filter or the four-way catalytic converter is regenerated by means of the residual oxygen conveyed into the exhaust system when the engine is winding down after the fuel injection has been switched off
Data Source
AI summary
In a method for the regeneration of a particulate filter or of a four-way catalytic converter in an exhaust system of an internal combustion engine, an increase in the nitrogen oxide emissions during the regeneration of the particulate filter or of the four-way catalytic converter can be prevented or at least reduced. A particulate filter or a four-way catalytic converter is arranged in the exhaust system of an internal combustion engine. The fuel injection and the ignition are switched off in response to a request for the internal combustion engine to be turned off. Due to mass inertia, the internal combustion engine transitions from the switch-off rotational speed to a standstill whereby, during this phase, oxygen-rich air is conveyed into the exhaust passage. A partial regeneration of the filter or of the catalytic converter takes place with the oxygen contained in this fresh air, whereby the particulate mass discharged from the filter or the catalytic converter is determined by means of a computational model.