DPF PM Accumulation Estimation with Sensor Failure Handling
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Solution Overview
Problem
Conventional PM accumulation amount estimation devices inaccurately estimate PM accumulation in diesel particulate filters (DPFs) when the airflow meter fails, leading to frequent active regeneration, deteriorated fuel economy, and oil dilution.
Innovation Solution
A PM accumulation amount estimation device that computes the PM regeneration amount separately for oxygen and nitrogen dioxide, using alternative means such as pressure/temperature measurements or engine rotation speed and fuel injection data to estimate the airflow volume when the airflow meter is abnormal, ensuring accurate PM accumulation amount estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the airflow meter is used to compute PM regeneration amount, then the PM accumulation amount estimation is accurate under normal conditions, but the system becomes unreliable when the airflow meter fails or shows abnormalities
Solution Approach 1:
The system changes the parameters used for computation based on sensor status. When the airflow meter is normal, it uses airflow volume data; when the airflow meter shows abnormality, it switches to using engine rotation speed and fuel injection amount data instead, thereby maintaining estimation accuracy under different operating conditions
Solution Approach 2:
The system prepares alternative computation methods in advance for when the airflow meter fails. By pre-establishing backup calculation paths using other sensor data, the system cushions against the potential failure impact and ensures continuous reliable operation without interruption
2Measurement precision
If PM accumulation amount is overestimated due to disregarding PM regeneration amount, then the system avoids underestimation errors, but active regeneration is performed more frequently causing fuel economy deterioration
Solution Approach 1:
The system segments the PM regeneration process into two distinct components: regeneration by oxygen and regeneration by nitrogen dioxide. This segmentation allows separate computation and more precise tracking of each regeneration mechanism, preventing overestimation while maintaining accuracy
Solution Approach 2:
The system dynamically adjusts computation parameters based on sensor status. By switching between different parameter sets (airflow meter data versus engine rotation speed and fuel injection data), the system maintains accurate PM accumulation estimation without unnecessary overestimation that would trigger excessive regeneration
3Reliability
If the airflow meter is frequently monitored and replaced to ensure accuracy, then measurement reliability improves, but device complexity and maintenance cost increase
Solution Approach 1:
The system makes the PM accumulation estimation computation universal by implementing multiple computation paths that can handle both normal and abnormal sensor conditions. The control device automatically selects the appropriate computation method based on sensor status, eliminating the need for separate systems for different failure modes
Solution Approach 2:
The control device acts as an intermediary that mediates between the airflow meter and the PM accumulation estimation. It monitors sensor status and intelligently switches between different computation methods, shielding the overall system from sensor failures without requiring complex hardware modifications
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
Enables accurate PM accumulation amount estimation in DPFs even with airflow meter abnormalities, preventing issues like fuel economy deterioration and oil dilution by continuing PM regeneration amount computation through alternative means.
Implementation Method 1
The DPF is a PM collecting device using a filter and is arranged in an exhaust path. The DPF is configured to collect PM such as soot exhausted from the engine by a filter
Implementation Method 2
a PM regeneration amount of PM regenerated by oxygen in the exhaust gas
Implementation Method 3
A part of the PM collected by the DPF is combusted by exhaust gas of high temperature exhausted from the engine (natural regeneration)
Implementation Method 4
a PM regeneration amount of PM regenerated by nitrogen dioxide in the exhaust gas
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A PM accumulation amount estimation device 50 is provided with an exhaust amount computation means 51 for computing PM exhaust amount which is discharged in an exhaust gas passage 3, and a passive regeneration amount computation means 52 for computing a PM regeneration amount in a DPF 7, and is configured to estimate the PM accumulation amount in the DPF 7 from the difference between the PM exhaust amount computed by the exhaust amount computation means 51 and the PM regeneration amount computed by the passive regeneration amount computation means 52. The PM accumulation amount estimation device 50 is further configured such that, when an abnormality is found in an airflow meter 31, the PM regeneration amount from NO2 is computed, and the PM accumulation amount in the DPF is estimated, without using the airflow amount measured by the airflow meter 31.