Recursive Kalman Filter for Diesel Particulate Filter Soot Loading
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Solution Overview
Problem
Existing diesel particulate filter (DPF) regeneration systems struggle with non-uniform soot distribution, leading to potential 'runaway' regeneration and increased engine backpressure, as they rely on pressure drop measurements that may underestimate actual soot loading, especially during high flow velocities and passive regeneration.
Innovation Solution
A method using a recursive Kalman filter to update soot loading estimates based on pressure drop measurements, allowing for precise triggering and stopping of active regeneration, accounting for non-uniform soot distribution and adjusting for exhaust gas flow velocity and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure drop measurement is used to trigger active regeneration, then the regeneration can be controlled, but the soot loading may be underestimated when soot distribution is non-uniform, leading to potential runaway regeneration
Solution Approach 1:
A recursive filter is introduced as an intermediary between the pressure drop measurement and the soot loading estimate. The filter processes the pressure drop signal and combines it with a soot generation model to produce a corrected soot loading estimate that accounts for non-uniform distribution, thereby resolving the underestimation problem while maintaining measurement-based control
Solution Approach 2:
The system uses feedback from the pressure drop measurement continuously updated through recursive filtering to adjust the soot loading estimate. This feedback mechanism allows the system to adapt to changing operating conditions and correct for non-uniform soot distribution in real-time, preventing runaway regeneration
2Device complexity
If active regeneration is triggered based on uniform soot distribution assumption, then the control system is simple, but it may miss localized high soot areas that could cause runaway regeneration
Solution Approach 1:
The system changes the parameter used for regeneration triggering from direct pressure drop threshold to a recursively filtered soot loading estimate. This parameter transformation allows the system to maintain simplicity while incorporating correction for non-uniform soot distribution, preventing localized runaway events
3Reliability
If regeneration is performed frequently to prevent runaway, then DPF integrity is maintained, but fuel consumption increases
Solution Approach 1:
The system replaces the simple mechanical pressure drop threshold trigger with a sophisticated recursive filtering algorithm that processes the same pressure drop signal. This substitution enables more accurate determination of actual soot loading, allowing regeneration to be performed only when truly necessary, thus reducing fuel consumption while maintaining DPF integrity
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 ensures accurate estimation of soot loading, preventing damage to the DPF and optimizing engine operation by triggering regeneration only when necessary, thereby maintaining DPF integrity and reducing fuel consumption.
Implementation Method 1
a pressure drop across the DPF is measured
Implementation Method 2
An initial estimate of soot loading in the DPF is provided to a recursive filter. Using the recursive filter, the initial estimate of soot loading is updated in view of the measured pressure drop to provide an updated estimate of soot loading in the DPF
Implementation Method 3
burning off the soot, through a so-called active regeneration by O2 oxidation, in a controlled manner
Implementation Method 4
Active regeneration typically occurs at temperatures greater than 550 °C
Implementation Method 5
so-called passive regeneration, which occurs when NO2 in the exhaust gas oxidizes the soot. Passive regeneration typically occurs at temperatures of about 250 °C to 450 °C
Data Source
Figure 1
AI summary
A method and apparatus for maintaining a diesel particulate filter (DPF) is provided. A pressure drop across the DPF is measured and an initial estimate of soot loading in the DPF is provided to a recursive filter. Using the recursive filter, the initial estimate of soot loading is updated in view of the measured pressure drop to provide an updated estimate of soot loading in the DPF. Active regeneration of the DPF is triggered when an earliest one of at least one triggering condition occurs, the updated estimate of soot loading reaching a predetermined value being one of the at least one triggering condition.