Ceramic Honeycomb Structure Pore Diameter Distribution
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Solution Overview
Problem
Ceramic honeycomb filters struggle to effectively capture nano-particles from diesel engine exhaust gases at the early stage of use while maintaining low pressure loss, failing to meet stricter exhaust gas regulations due to insufficient number-based capturing ratio and pressure loss characteristics.
Innovation Solution
A ceramic honeycomb structure with specific porosity and pore diameter distribution, including porosity of 50-63%, pore diameters d2, d5, d10, d50, d85, d90, and d98, and a difference between these diameters, optimized for improved capturing efficiency of nano-particles without significant pressure loss deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If porosity and pore diameter distribution are optimized for high nano-particle capturing ratio, then capturing efficiency improves, but pressure loss increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling porosity (40-60%) and pore diameter distribution (d50: 10-20 μm, d90: 3.5-9 μm, d98: 2.5 μm or less) to achieve optimal balance between capturing efficiency and pressure loss characteristics
Solution Approach 2:
The patent applies local quality by creating different pore size zones within the cell walls - larger pores (d50) for maintaining low pressure loss and gas flow, and smaller pores (d90, d98) for effective nano-particle capture, with each zone serving its specific function
2Reliability
If pore diameter distribution is controlled for improved nano-particle capture, then capturing ratio increases, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise parameter ranges for pore diameters (d50: 10-20 μm, d90: 3.5-9 μm, d98: 2.5 μm or less) and porosity (40-60%) to achieve the desired pore diameter distribution, balancing manufacturing feasibility with performance requirements
Solution Approach 2:
The patent employs preliminary action by pre-forming the green body with controlled pore structure through molding techniques before sintering, ensuring the final product achieves the target pore diameter distribution without requiring complex post-processing
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
The structure effectively captures nano-particles with an improved number-based capturing ratio even before accumulation, maintaining low pressure loss characteristics when particles are captured, thus meeting stricter exhaust gas regulations.
Implementation Method 1
PM is captured, cleaning the exhaust gas
Implementation Method 2
an exhaust gas flows into the outlet-side-plugged flow paths, which are open on the exhaust-gas-inlet-side end surface. While passing through the cell walls, particularly through communicating pores on and in the cell walls, PM is captured
Data Source
Figure 1~2
Figure 3~4
AI summary
A ceramic honeycomb structure having pluralities of flow paths partitioned by porous cell walls, (a) the cell walls having porosity of 50-63%; and (b) in a pore diameter distribution in the cell walls measured by mercury porosimetry, (i) a pore diameter at a cumulative pore volume corresponding to 2% of the total pore volume being more than 180 µm and 250 µm or less, a pore diameter at 5% being 55-150 µm, a pore diameter d10 at 10% being 17-40 µm, a pore diameter d50 at 50% being 10-20 µm, a pore diameter at 85% being 5.5-10 µm, a pore diameter d90 at 90% being 3.5-9 µm, a pore diameter d98 at 98% being 2.5 µm or less, (d10 - d90)/d50 being 1.3-2, (d50 - d90)/d50 being 0.45-0.75, and (d10 - d50)/d50 being 0.75-1.4; (ii) the difference between a logarithm of the pore diameter at a cumulative pore volume corresponding to 20% of the total pore volume and a logarithm of the pore diameter at 80% being 0.39 or less; and (iii) the volume of pores of more than 100 µm being 0.03 cm3/g or less.