Pillar-Shaped Honeycomb Filter Porosity Gradient
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Solution Overview
Problem
Existing filters with a pillar-shaped honeycomb structure bonded via a bonding material lack improvement in catalytic performance, as the catalyst slurry tends to fill the bonding material and the outer peripheral side walls, reducing the effectiveness of catalyst support on partition walls.
Innovation Solution
By adjusting the average porosity of the outer peripheral side wall to be lower than that of the partition walls, and setting the average thickness of the outer peripheral side wall to a specific ratio relative to the partition walls, it becomes difficult for the catalyst to be supported on the outer peripheral side wall and the bonding material, thereby increasing the ratio of catalyst supported on the partition walls that contributes to improved catalytic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the outer peripheral side wall and bonding material are made highly porous to maintain structural integrity, then the strength and thermal shock resistance are improved, but the catalyst slurry fills these spaces reducing catalytic performance
Solution Approach 1:
The patent applies different porosity levels to different regions: the outer peripheral side wall is made less porous (30-60% porosity) to prevent catalyst slurry infiltration and maintain structural integrity, while the partition walls maintain high porosity (70-90% porosity) to ensure catalyst support functionality and exhaust gas flow. This local differentiation resolves the contradiction by optimizing each region for its specific function.
Solution Approach 2:
The patent changes the porosity parameter of the outer peripheral side wall from the conventional high porosity (matching partition walls) to a controlled lower porosity range (30-60%). This parameter modification prevents catalyst slurry from filling the outer wall and bonding material, thereby maintaining catalytic performance while preserving structural strength.
2Reliability
If the outer peripheral side wall porosity is reduced to prevent catalyst slurry infiltration, then catalytic performance is improved, but the structural integrity and thermal shock resistance may be compromised
Solution Approach 1:
The patent differentiates the porosity between the outer peripheral side wall and partition walls. The outer peripheral side wall uses lower porosity (30-60%) for structural integrity and preventing slurry infiltration, while partition walls use higher porosity (70-90%) for catalyst support. This local quality differentiation allows each component to be optimized for its primary function without compromising overall performance.
3Reliability
If the catalyst amount is increased to improve catalytic performance, then exhaust gas purification is enhanced, but the catalyst slurry fills the bonding material and outer peripheral side wall reducing effectiveness
Solution Approach 1:
By making the outer peripheral side wall less porous (30-60% porosity), the patent creates a barrier that prevents catalyst slurry from infiltrating this region and the bonding material. This ensures that catalyst is concentrated in the partition walls where it is most effective, improving catalyst distribution efficiency and catalytic performance.
Solution Approach 2:
The porosity parameter of the outer peripheral side wall is modified to a lower range (30-60%), which controls catalyst slurry infiltration. This parameter change ensures that catalyst remains effectively distributed on the partition walls rather than being wasted in the outer wall and bonding material, thereby improving catalyst utilization efficiency.
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 configuration enhances catalytic performance by ensuring a higher proportion of the catalyst is effectively supported on the partition walls, thereby improving exhaust gas purification efficiency while maintaining the same catalyst amount.
Implementation Method 1
side faces of a plurality of pillar-shaped honeycomb structure segments made of porous ceramics are bonded together via a bonding material
Implementation Method 2
filters typified by DPFs and GPFs that pass exhaust gas through air-permeable small-pore partition walls and filtrate PM such as soot
Implementation Method 3
The filter may support various types of catalysts such as an SCR catalyst in order to simultaneously provide an exhaust gas purifying function such as NOx purifying
Data Source
AI summary
A filter including a plurality of pillar-shaped honeycomb structure segments made of porous ceramics, side faces of the segments being bonded together via a bonding material, wherein each of the pillar-shaped honeycomb structure segments includes an outer peripheral side wall, and partition walls partitioning a plurality of cells extending from a first end face to a second end face, and in each of the pillar-shaped honeycomb structure segments, an average porosity of the outer peripheral side wall is lower than that of the partition walls.