EGR Control via Exhaust Back-Pressure Feedback
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Solution Overview
Problem
The accumulation of soot in diesel particulate filters (DPFs) affects the efficiency of exhaust gas recirculation (EGR) control in diesel engines, leading to variations in engine performance due to changing trapping efficiency and regeneration cycles, which have not been fully addressed by existing technologies.
Innovation Solution
A processor-based engine control system processes data to adjust EGR volumetric efficiency and develop flow control data, accounting for soot accumulation in the DPF, thereby correcting the total mass flow through the engine and optimizing EGR system operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If soot accumulates in the DPF during normal operation, then the DPF trapping efficiency decreases and EBP fluctuates, but the EGR control accuracy deteriorates
Solution Approach 1:
The control system continuously monitors EBP fluctuations and uses this feedback to dynamically adjust EGR control strategies. The processor detects changes in EBP caused by soot accumulation and modifies EGR valve positioning accordingly, creating a closed-loop control system that maintains accuracy despite DPF aging
Solution Approach 2:
The system changes operational parameters by adjusting EGR volumetric efficiency values based on detected EBP fluctuations. When soot accumulation causes EBP to change, the control system modifies EGR control parameters to compensate, maintaining optimal EGR flow control throughout the DPF's service life
2Reliability
If forced regeneration is performed to burn off accumulated soot, then DPF trapping efficiency is restored, but engine operating conditions must be significantly altered
Solution Approach 1:
The control system performs preliminary adjustments to EGR control before regeneration is needed. By continuously adapting EGR control to EBP fluctuations during normal operation, the system prevents excessive soot accumulation that would force aggressive regeneration cycles, maintaining smoother engine operation
Solution Approach 2:
The system transitions from static EGR control to dynamic EGR control that adapts in real-time to DPF conditions. The processor continuously adjusts EGR parameters based on EBP fluctuations, allowing the system to respond flexibly to changing DPF states without requiring extreme operating condition changes
3Device complexity
If the EGR control system does not account for soot accumulation, then the control system remains simple, but EGR volumetric efficiency data becomes inaccurate
Solution Approach 1:
The system introduces EBP as an intermediary parameter that links DPF soot accumulation status to EGR control adjustments. Rather than directly measuring soot accumulation, the system uses EBP fluctuations as a mediator to infer DPF state and adjust EGR control accordingly, adding minimal complexity while improving accuracy
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 stabilizes EGR control, improving engine performance by compensating for soot accumulation and maintaining efficient exhaust gas recirculation, even during varying soot accumulation and regeneration cycles.
Implementation Method 1
An exhaust system of a diesel engine that comprises a DPF is capable of physically trapping diesel particulate matter (DPM) in engine exhaust gas passing through the exhaust system
Implementation Method 2
The organic constituents of trapped DPM, i.e. carbon and SOF, are oxidized within the DPF at appropriate times and under appropriate conditions to form CO2 and H2O
Implementation Method 3
Control of recirculated exhaust gas is performed by an exhaust gas recirculation (EGR) system that typically includes an EGR valve that is controlled by the engine control system
Data Source
AI summary
An engine (10) uses a method for counteracting the effect of soot accumulation in a diesel particulate filter (DPF 38) in a diesel engine exhaust system (16) on the control of exhaust gas recirculation (EGR) through an EGR system (40). Engine speed (N) and indicated engine torque (TQI) data are processed to select from a map (62) a data value for present EGR volumetric efficiency. The selected data value and certain other data, including data that accounts for present soot accumulation in the DPF, are processed to develop a data value indicative of present total mass flow. The data value indicative of present total mass flow and still other data are processed to develop flow control data for controlling flow of exhaust gas through the EGR system.