Plugged Honeycomb Structure for Diesel Filters
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Solution Overview
Problem
Conventional honeycomb structures used in diesel particulate filters face challenges in maintaining effective filtration area and mechanical strength while minimizing labor and trouble in forming plugged parts, especially in partial cells of the outermost peripheral portion, which often result in large pressure loss and reduced productivity.
Innovation Solution
A plugged honeycomb structure is designed where partial cells of the outermost peripheral portion are plugged either in their entirety or only at one end based on specific cell area ratios, with the material for plugged parts being aluminum titanate or its composite and partition walls being cordierite or its composite, ensuring lower rigidity, higher heat capacity, and reduced thermal conductivity compared to the partition walls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If plugged parts are formed in all partial cells of outermost peripheral portion, then effective filtration area is maximized, but labor and trouble increase significantly
Solution Approach 1:
The patent applies different plugging strategies to different regions: partial cells with area ratio ≤30% are plugged in entire length with outer wall, while partial cells with area ratio >30% have plugged parts only at one end. This local differentiation optimizes both filtration area and manufacturing ease by adapting the plugging method to the specific characteristics of each cell region.
2Strength
If partial cells of outermost peripheral portion are plugged in entire length and formed integrally with outer wall, then mechanical strength increases, but effective filtration area is reduced
Solution Approach 1:
The patent selectively applies integral plugging (plugged in entire length with outer wall) only to partial cells whose area ratio is 30% or less, while other partial cells receive plugged parts only at one end. This localized approach ensures mechanical strength is enhanced where most needed (smaller, more irregular cells) while preserving filtration area in larger cells.
3Productivity
If not only partial cells but also part of complete cells are plugged and formed integrally with outer wall, then productivity increases, but pressure loss increases excessively
Solution Approach 1:
The patent restricts integral plugging (which improves productivity) to only those partial cells with area ratio ≤30%, and explicitly avoids plugging complete cells integrally. Instead, complete cells and larger partial cells receive plugged parts only at one end, maintaining lower pressure loss while still achieving productivity benefits in the most problematic regions.
4Quantity of substance
If plugged parts are formed in partial cells with very small area (less than 5% of complete cell), then filtration area is optimized, but formation difficulty and labor increase much
Solution Approach 1:
The patent identifies partial cells with area ratio ≤30% as requiring special handling and applies integral plugging with outer wall formation to these cells. This automatically includes the very small cells (≤5% of complete cell area) and handles them through a standardized integral forming process, reducing the complexity and labor associated with forming plugged parts in these difficult-to-access small cells.
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 prevents significant reduction in effective filtration area and excessive pressure loss, reduces the difficulty and labor in forming plugged parts, and enhances productivity without compromising the mechanical strength and thermal performance of the honeycomb structure.
Implementation Method 1
the material for plugged parts being aluminum titanate or its composite and partition walls being cordierite or its composite, ensuring lower rigidity, higher heat capacity, and reduced thermal conductivity compared to the partition walls
Implementation Method 2
the material for plugged parts being aluminum titanate or its composite and partition walls being cordierite or its composite, ensuring lower rigidity, higher heat capacity, and reduced thermal conductivity compared to the partition walls
Data Source
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AI summary
A honeycomb structure comprising porous partition walls which form, by surrounding, a plurality of cells extending between the two ends faces of the honeycomb structure, and an outer wall formed integrally with the partition walls. The cells consist of partial cells of outermost peripheral portion, having incomplete cell sections, which are located at the outermost peripheral portion of the honeycomb structure and are in partial contact with the outer wall, and complete cells having a complete cell section, other than the partial cells of outermost peripheral portion. In the complete cells, a plugged part is formed at one end of each complete cell so that each end face of the honeycomb structure shows a checkerwise plugging pattern. In the partial cells of outermost peripheral portion to be plugged according to the above-mentioned plugging pattern, part of them is plugged in the entire length and formed integrally with the outer wall and remaining cells have each a plugged part only at one end.