Particulate Filter with Micropore and Macropore Zones
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Solution Overview
Problem
The particulate filter in internal combustion engine exhaust purification systems is prone to cracking due to large temperature differences between micropore and macropore zones, caused by uneven particulate matter oxidation, leading to potential damage and increased pressure loss.
Innovation Solution
An exhaust purification system with a particulate filter having alternately arranged exhaust gas inflow and outflow passages separated by porous partition walls with micropore and macropore zones, where PM removal control is executed when the trapped particulate matter difference exceeds a threshold, maintaining the filter in an oxidizing atmosphere and adjusting pore sizes to manage ash and particulate matter trapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PM removal control is executed to remove trapped particulate matter, then the particulate matter is oxidized and removed from the filter, but a large temperature difference occurs between micropore zones and macropore zones causing the filter to crack
Solution Approach 1:
The partition walls are designed with spatially varying pore sizes: micropore zones at upstream sides with smaller pores that trap particulate matter, and macropore zones at downstream sides with larger pores that allow ash to pass through. This local differentiation controls where oxidation occurs and how heat is distributed during PM removal control, preventing excessive temperature differences that would cause cracking.
2Reliability
If pore size at micropore zones is set to trap particulate matter, then PM trapping efficiency is improved, but a relatively large amount of PM accumulates there causing excessive heat generation during oxidation
Solution Approach 1:
The partition walls incorporate micropore zones with smaller pore sizes (e.g., 5-20 μm) at upstream sides optimized for trapping particulate matter, while macropore zones with larger pore sizes (e.g., 20-50 μm) are positioned at downstream sides. This spatial differentiation ensures PM is trapped efficiently at micropore zones but can be oxidized and removed more uniformly when PM removal control is executed, as the oxidizing atmosphere can penetrate more effectively through the macropore zones.
Solution Approach 2:
The partition walls are segmented into functionally distinct micropore zones and macropore zones along the exhaust gas flow direction. This segmentation allows different regions to perform different functions: micropore zones for initial PM trapping and macropore zones for facilitating oxidizing atmosphere penetration and ash passage, thereby distributing heat generation more evenly during PM removal operations.
3Loss of energy
If pore size at macropore zones is set to allow ash passage, then ash accumulation is reduced and pressure loss is kept low, but particulate matter can also pass through reducing trapping efficiency
Solution Approach 1:
The partition walls are designed with micropore zones at upstream sides having smaller pore sizes that effectively trap particulate matter, while macropore zones at downstream sides have larger pore sizes that allow ash to pass through freely. The sequential arrangement ensures that PM is trapped at the micropore zones before exhaust gas reaches the macropore zones, so the larger pores in macropore zones do not compromise overall PM trapping efficiency while effectively reducing ash accumulation and pressure loss.
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 solution reduces the risk of filter damage while maintaining low pressure loss by controlling the temperature and particulate matter distribution across the filter, preventing excessive heat generation and ash accumulation.
Implementation Method 1
a pore size of the partition walls in the micropore zones is set so that particulate matter and ash can be trapped by the partition walls at the micropore zones, a pore size of the partition walls in the macropore zones is set so that ash can pass through the partition walls at the macropore zones
Implementation Method 2
PM removal control, which increases the temperature of the particulate filter to a PM removal temperature and maintains the same to the PM removal temperature while maintaining the particulate filter in an oxidizing atmosphere in order to remove the particulate matter on the particulate filter
Data Source
AI summary
The risk of a particulate filter from being damaged is reduced while an increase in pressure loss of the particulate filter due to ash is suppressed. Micropore zones are defined at upstream sides of partition walls of a particulate filter and macropore zones are defined at downstream sides of partition walls. The pore size of the partition walls at the micropore zones is set so that the particulate matter and the ash can be trapped by the partition walls at the micropore zones, while the pore size of the partition walls at the macropore zones is set so that the ash can pass through the partition walls at the macropore zones. When the difference dQPM between the quantity of the particulate matter which is trapped at the micropore zones and the quantity of particulate matter which is trapped at the macropore zones exceeds a predetermined threshold value, PM removal control is executed.