Particulate Filter Regeneration Timing Optimization
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Solution Overview
Problem
Existing methods for regenerating particulate filters in vehicles often lead to reduced ammonia storage capacity in SCR catalysts, causing increased ammonia slip and decreased NOx reduction capabilities, which affects emissions quality and can result in urea injector degradation due to high temperatures during regeneration.
Innovation Solution
The method involves opportunistically scheduling the regeneration of diesel particulate filters based on predicted vehicle drive cycles, ammonia storage levels, and soot loads, adjusting urea injection limits and ammonia storage set points to optimize regeneration timing and reduce ammonia slip, and terminating regeneration when ammonia levels or urea injector temperatures become critical.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PF regeneration is performed to burn off soot particles, then soot removal efficiency is improved, but ammonia storage capacity in SCR catalyst decreases and ammonia slip increases
Solution Approach 1:
The system performs preliminary actions by predicting the time to reach destination and predicting ammonia levels before regeneration occurs. The controller proactively adjusts urea injection limits and ammonia storage set points in advance to ensure adequate ammonia remains in the SCR catalyst after regeneration, preventing ammonia slip while still allowing effective soot removal.
Solution Approach 2:
The system dynamically adjusts regeneration parameters based on real-time conditions. The controller modifies urea injection limits, ammonia storage set points, and regeneration timing based on predicted drive cycles, current ammonia levels, and soot load conditions to optimize the balance between soot removal and ammonia preservation.
2Productivity
If PF regeneration is scheduled to terminate at end of drive cycle, then soot removal is maximized, but ammonia remaining in SCR catalyst is insufficient for subsequent engine start
Solution Approach 1:
The system calculates predicted ammonia levels at the end of the drive cycle in advance and uses this prediction to determine optimal regeneration termination timing. By acting beforehand, the controller ensures that regeneration terminates at the right moment to maximize soot removal while preserving sufficient ammonia for the subsequent engine start.
Solution Approach 2:
The system continuously monitors actual ammonia levels and compares them against predicted values and threshold criteria. This feedback mechanism allows the controller to adjust regeneration termination timing based on real-time ammonia consumption, ensuring adequate ammonia remains in the catalyst while maximizing soot removal effectiveness.
3Productivity
If higher exhaust temperature is maintained during PF regeneration, then soot oxidation is enhanced, but urea injector temperature increases causing degradation
Solution Approach 1:
The system monitors urea injector temperature in real-time during regeneration and uses this feedback to control the regeneration process. When the injector temperature approaches the degradation threshold, the controller adjusts or terminates regeneration to protect the injector while still achieving adequate soot removal.
Solution Approach 2:
The system establishes temperature thresholds and protective measures in advance. By predicting temperature rises and preparing termination criteria beforehand, the system prevents urea injector degradation before it occurs, while still allowing sufficient regeneration time for effective soot oxidation.
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 improves fuel efficiency, emissions quality, and protects urea injector hardware by optimizing regeneration timing and ammonia management, ensuring adequate ammonia storage for subsequent engine starts and reducing the risk of injector degradation.
Implementation Method 1
selective catalytic reduction (SCR) catalysts, may reduce the amount of soot and NOx emissions from an engine by trapping soot particles and reducing NOx to nitrogen and water, respectively
Implementation Method 2
reducing NOx to nitrogen and water
Implementation Method 3
ensuring that exhaust gas entering the PF is of a certain composition in order to burn or oxidize the particulate matter
Implementation Method 4
Regeneration may be achieved by raising a temperature of the PF to a predetermined level, maintaining the temperature at the predetermined level, and ensuring that exhaust gas entering the PF is of a certain composition in order to burn or oxidize the particulate matter
Data Source
AI summary
Methods and systems are provided for regenerating an exhaust particulate filter based on a projected vehicle drive cycle and catalyst ammonia storage level. In one example, a method may include scheduling a PF regeneration during a regeneration window to maintain a threshold ammonia level in an exhaust catalyst, at the end of the drive cycle.