Particulate Filter Regeneration via Engine Shutdown Segmentation
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Solution Overview
Problem
Turbocharged direct-injection engines face challenges in particulate filter regeneration due to increased soot generation, particularly at high speeds and loads, leading to elevated NOx emissions when excess oxygen is used for regeneration, as it can saturate the oxygen storage capacity of three-way catalysts.
Innovation Solution
Implementing a method to regenerate the particulate filter during engine shutdown or rest, reducing engine running regeneration to minimize NOx emissions, and regenerating during engine combustion when more particulate is stored, allowing for more flexible and efficient regeneration processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If particulate filter regeneration is performed during engine running with excess oxygen, then regeneration effectiveness is improved, but NOx emissions increase due to saturation of oxygen storage capacity in three-way catalysts
Solution Approach 1:
The patent segments the regeneration process into two distinct phases: (1) engine running regeneration with controlled oxygen levels, and (2) engine shutdown regeneration with excess oxygen. This segmentation allows the system to achieve complete regeneration by combining both approaches while avoiding NOx emissions during the excess oxygen phase since the engine is not running.
Solution Approach 2:
The patent performs preliminary regeneration during engine running before shutdown, removing a portion of accumulated particulates. Then, during engine shutdown, excess oxygen is introduced to complete the regeneration process. This preliminary action during engine operation reduces the overall regeneration burden during shutdown while minimizing NOx emissions.
2Reliability
If engine running regeneration is used to remove particulates, then regeneration is achieved, but engine emissions increase due to excessive lean operation
Solution Approach 1:
The patent divides the regeneration process into engine running phase and engine shutdown phase. During engine running, regeneration is performed with controlled oxygen to remove some particulates. During engine shutdown, the remaining particulate removal is accomplished with excess oxygen, eliminating the need for excessive lean operation during engine running and thereby reducing engine running emissions.
Solution Approach 2:
The patent converts the typically harmful condition of excess oxygen (which causes high NOx emissions when engine is running) into a beneficial condition by introducing it during engine shutdown. During shutdown, excess oxygen enables complete regeneration without the harmful side effect of engine running emissions, thus converting a potential harm into a benefit.
3Reliability
If excess oxygen is introduced during engine shutdown for regeneration, then regeneration is enhanced, but oxygen storage capacity of three-way catalysts is saturated
Solution Approach 1:
The patent segments the oxygen introduction strategy into two phases: controlled oxygen during engine running to maintain catalyst oxygen storage capacity, and excess oxygen during engine shutdown to enhance regeneration efficiency. This segmentation allows the system to utilize excess oxygen when it won't harm catalyst performance (during shutdown) while preserving catalyst functionality during engine operation.
Solution Approach 2:
The patent performs preliminary regeneration during engine running with controlled oxygen, removing some particulates before shutdown. This preliminary action reduces the particulate load, allowing the excess oxygen introduced during shutdown to be more effective without completely saturating the catalyst's oxygen storage capacity, as some capacity is preserved from the controlled running phase.
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 reduces engine running NOx emissions by minimizing excessive lean operation and ensures effective particulate filter regeneration while maintaining emission control, even when excess oxygen is present during shutdown.
Implementation Method 1
utilize a particulate filter in the exhaust
Implementation Method 2
regeneration of the filter
Implementation Method 3
oxygen storage capacity of three-way catalysts
Data Source
AI summary
Systems and methods for controlling regeneration of a particulate filter downstream of an engine having a plurality of cylinders are provided. One exemplary method includes, during first conditions, spinning down the engine to non-combusting engine rest, and regenerating the particulate filter at least during engine rest. The method also includes, during second conditions, regenerating the particulate filter during combustion of at least one cylinder of the engine. By regenerating the particulate filter during engine shutdown and/or engine rest in some conditions, it is possible to reduce engine running regeneration, which can thereby lead to reduced engine running emissions.