Engine-Out NOx Estimation for Diesel Aftertreatment Control
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Solution Overview
Problem
Current methods for reducing NOx emissions from diesel engines, such as NOx reduction catalysts and diesel particulate filters, face challenges in accurately estimating the amount of NOx emissions and determining the need for regeneration, leading to inefficiencies in emission control.
Innovation Solution
A system and method for estimating engine-out NOx emissions using engine speed, fuel injection quantity, cylinder pressure, intake O2 concentration, and effective temperature, which are modeled into a mathematical algorithm to provide real-time data for controlling the regeneration of NOx reduction devices like lean NOx traps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If NOx reduction catalysts are used to reduce NOx emissions, then NOx emissions are reduced, but accurate estimation of NOx emissions and determination of regeneration need becomes challenging
Solution Approach 1:
The patent introduces an intermediary estimation system that uses readily measurable parameters (intake air flow, coolant temperature, EGR valve position, fuel injection quantity, engine speed) to calculate and estimate NOx emissions. This intermediary calculation bridge connects measurable engine operating parameters to the difficult-to-measure NOx emissions, enabling accurate estimation without direct NOx measurement equipment.
Solution Approach 2:
The patent replaces complex direct measurement systems with a mathematical calculation model. Instead of using sophisticated sensors to directly measure NOx emissions, the system substitutes a computational approach that uses standard engine sensors and pre-established relationships between operating parameters and NOx formation to estimate emissions accurately.
2Object-generated harmful factors
If lean NOx traps are used for NOx reduction, then NOx emissions are reduced, but the device requires periodic regeneration which complicates the emission control system
Solution Approach 1:
The patent implements a feedback mechanism where the estimated NOx emissions are continuously fed back to the control system. This feedback enables the controller to monitor the accumulation of NOx in the lean NOx trap and determine when regeneration is needed, creating a closed-loop control system that automatically manages the regeneration process based on actual emission conditions.
Solution Approach 2:
The estimation system enables the emission control system to self-manage its own maintenance needs. By continuously estimating NOx emissions and monitoring trap loading, the system can autonomously determine when regeneration is required and initiate the appropriate control actions, reducing the need for external intervention or complex manual monitoring systems.
3Loss of time
If real-time NOx estimation is implemented, then timely regeneration of NOx reduction devices can be achieved, but additional sensors and computational resources are required
Solution Approach 1:
The patent performs preliminary estimation of NOx emissions using readily available sensor data from the engine management system. By calculating NOx emissions in advance based on operating parameters before the actual regeneration event is needed, the system can proactively determine when regeneration should occur, ensuring timely maintenance without requiring complex real-time measurement systems.
Data Source
AI summary
A method and system for estimating engine-out NOx from a diesel engine. The estimation is calculated from a mathematical model that expresses engine-out NOx as functions of cylinder pressure, intake oxygen, and effective temperature, respectively. Input data for each of these functions may be obtained from fuel quantity data and from measured data, the latter including intake pressure, cylinder pressure, intake oxygen concentration, coolant temperature, and intake manifold temperature.