Particulate Filter Regeneration During Engine Shutdown
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Turbocharged direct-injection engines face challenges in particulate filter regeneration due to increased soot generation, particularly at high speeds and loads, which can lead to elevated NOx emissions when excess oxygen is used for regeneration, saturating the oxygen storage capacity of three-way catalysts.
Innovation Solution
Regenerating the particulate filter during engine shutdown or rest conditions, rather than during engine operation, to reduce NOx emissions by controlling exhaust constituents and adjusting engine parameters such as air-fuel ratio and throttle opening to manage excess oxygen levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If excess oxygen is directed to the particulate filter for regeneration during engine operation, then soot is reduced, but NOx emissions increase due to saturation of three-way catalyst oxygen storage capacity
Solution Approach 1:
The system performs particulate filter regeneration during engine shutdown conditions, before the engine starts again. This preliminary action during shutdown allows oxygen to be directed to the filter without competing with the three-way catalyst's oxygen storage needs during active operation, thereby reducing soot while avoiding NOx emissions that would result from catalyst saturation during engine running conditions
Solution Approach 2:
The invention extracts the regeneration process from the engine operation phase and relocates it to the engine shutdown phase. By separating the regeneration function from the operational phase, the system can provide excess oxygen to the particulate filter without interfering with the three-way catalyst's ability to store oxygen during normal operation, thus preventing NOx formation
2Loss of substance
If regeneration is performed during engine operation, then soot is reduced, but oxygen storage capacity of three-way catalyst is saturated
Solution Approach 1:
The system performs regeneration as a preliminary action during engine shutdown, before the engine resumes operation. This timing allows the three-way catalyst to maintain its oxygen storage capacity for use during subsequent operation, while still achieving soot reduction through regeneration during the shutdown interval
Solution Approach 2:
The invention segments the engine operation into distinct phases: operation phase where the three-way catalyst stores oxygen, and shutdown phase where regeneration occurs using excess oxygen. This temporal segmentation allows both functions—oxygen storage and regeneration—to occur without competing for the same oxygen resources
3Object-generated harmful factors
If engine parameters are adjusted to control excess oxygen levels, then emission control integrity is maintained, but system complexity increases
Solution Approach 1:
The system uses periodic engine shutdown conditions to perform regeneration, leveraging the natural periodic operation of the engine. During these periodic shutdown intervals, the control system adjusts parameters to direct excess oxygen to the particulate filter, while during operation intervals, normal emission control applies. This periodic approach maintains emission integrity without requiring continuously complex control mechanisms
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 effectively reduces NOx emissions by avoiding the saturation of three-way catalysts during regeneration, maintaining emission control integrity while addressing accumulated compounds in the exhaust system.
Implementation Method 1
a particulate filter downstream of a three-way catalyst
Implementation Method 2
downstream of an engine in a vehicle with a three-way catalyst and a particulate filter in an exhaust passage
Implementation Method 3
sufficient excess oxygen for regeneration in the exhaust may result in increased NOx emissions
Data Source
AI summary
Systems and methods for controlling regeneration of a particulate filter downstream of an engine in a vehicle are provided herein. One exemplary method includes, during an engine shutdown, increasing a throttle opening and regenerating a particulate filter downstream of a three-way catalyst. The method also includes, during an engine start following an engine shutdown, setting one or more engine parameters based on whether the particulate filter was regenerated during a last engine shutdown before the engine start.