Ceramic Filter Pore Depth Optimization
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Solution Overview
Problem
Current ceramic filters with pillar-shaped honeycomb structures face challenges in achieving both high particulate matter (PM) collection performance and low pressure loss, as existing methods for characterizing partition wall structures using X-ray CT scans, electron microscopes, or mercury intrusion methods are not optimal.
Innovation Solution
The use of a laser microscope to analyze the surface of partition walls, with specific conditions for equivalent circle diameter, pore depth, and number density of pores, such as a slope of 0 to 0.20, average pore depth of 2.5 to 5.0 μm, and number density of 600/mm² to 2450/mm², to optimize PM collection and pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pore path length is increased to improve PM collection performance, then the filtration efficiency is improved, but the pressure loss increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the pore path length distribution within a specific range (5-15 μm) and setting the cumulative frequency distribution to fall within 60-80%. This statistical parameter control allows optimization of both PM collection efficiency and pressure loss characteristics by adjusting the distribution characteristics rather than simply increasing or decreasing all pore paths uniformly.
Solution Approach 2:
The patent implements local quality by creating a non-uniform pore structure where different regions of the partition wall have different pore path lengths. By controlling the distribution so that cumulative frequency reaches 60-80% within the 5-15 μm range, the structure provides varied local filtration paths that balance deep particle capture with acceptable flow resistance.
2Reliability
If the pore density is increased to improve PM collection performance, then the filtration efficiency is improved, but the pressure loss increases
Solution Approach 1:
The patent applies parameter changes by controlling the pore density to fall within a specific range (300-1000 pores/mm²) and managing the opening area ratio within 10-30%. These parameter adjustments optimize the balance between having enough pores to capture particles effectively while maintaining sufficient open area to allow gas flow with minimal pressure loss.
3Loss of energy
If the partition wall porosity is increased to reduce pressure loss, then the gas flow resistance is reduced, but the PM collection performance deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the porosity within the range of 40-60%, which balances the competing requirements of maintaining low pressure loss and achieving high PM collection efficiency. This specific porosity range ensures sufficient open space for gas flow while providing adequate filtering capacity.
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 enables a ceramic filter with improved PM collection efficiency while maintaining low pressure loss by preventing particulate matters from penetrating deep into the partition walls and ensuring sufficient pore density for effective filtration.
Implementation Method 1
when observing a plurality of pores from a surface of the partition walls with a laser microscope
Implementation Method 2
when observing a plurality of pores from a surface of the partition walls with a laser microscope
Implementation Method 3
the exhaust gas passes through air-permeable small-pore partition walls to filtrate PMs such as soot
Data Source
AI summary
A ceramic filter having a pillar-shaped honeycomb structure, wherein when observing a plurality of pores from a surface of partition walls with a laser microscope and plotting an equivalent circle diameter (μm) of each pore on an X-axis and a pore depth (μm) of each pore on a Y-axis on a two-dimensional coordinate system, a slope of a regression line (y/x) obtained by a least squares method in a range of 20≤x≤40 is 0 to 0.20, an average value of the pore depth of the plurality of pores is 2.5 μm to 5.0 μm, and a number density of the plurality of pores is 600/mm2 to 2450/mm2.