Honeycomb Structure with Stepwise Partition Wall Intervals
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Solution Overview
Problem
Honeycomb structures used as catalyst bodies or filters face challenges in achieving high isostatic strength and thermal shock resistance while maintaining purification performance, due to decreased thickness and increased porosity, which leads to damage under vibration and high-temperature conditions, and are difficult to manufacture with existing dies.
Innovation Solution
A honeycomb structure with varying partition wall intervals and a die design that adjusts raw material flow rates to match interval changes, ensuring the partition walls can withstand pressure and maintain structural integrity, featuring a cell structure with parallel and intersecting partition walls and a die with lattice-shaped slits and varying hole sizes to prevent forming failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the thickness of the partition wall is reduced to increase purification performance, then the catalytic activity and porosity are improved, but the isostatic strength and thermal shock resistance decrease
Solution Approach 1:
The partition wall thickness is varied locally across different regions of the honeycomb structure. Specifically, the thickness increases from the center toward the outer circumference, allowing regions requiring higher strength (outer regions subjected to vibration) to have thicker walls while central regions maintain thinner walls for high porosity and catalytic activity.
2Productivity
If the porosity of the partition wall is increased to improve collection efficiency, then the purification performance is enhanced, but the thermal shock resistance and isostatic strength decrease
Solution Approach 1:
The partition wall structure is optimized locally by controlling porosity distribution. The outer circumferential region has lower porosity and higher density to withstand thermal shock during regeneration, while inner regions maintain higher porosity for efficient soot collection and catalytic activity.
3Productivity
If the partition wall thickness is reduced to increase catalytic activity, then the heat capacity is decreased and catalytic performance is improved, but the structural integrity under vibration decreases
Solution Approach 1:
The honeycomb structure employs spatially varying partition wall thickness where the outer circumferential region has increased thickness to provide mechanical strength against vibration, while the central region maintains reduced thickness for low heat capacity and high catalytic activity. This local differentiation resolves the contradiction between catalytic performance and structural integrity.
4Reliability
If uniform cell density is provided to improve thermal shock resistance, then the heat exchange ratio is improved, but the isostatic strength under vibration is insufficient
Solution Approach 1:
Instead of uniform cell density, the invention implements a gradient cell density distribution where cell density increases from the center toward the outer circumference. This allows the outer regions to have higher cell density for improved thermal shock resistance while the central region maintains lower density for adequate isostatic strength under vibration conditions.
Data Source
AI summary
A honeycomb structure has a cell structure section 3 an outer circumferential wall section 4. The cell structure section 3 includes a first partition wall group having partition walls 1a positioned in parallel and a second partition wall group having partition walls 1b which intersect the partition walls of the first partition wall group at right angles and are positioned in parallel. In this honeycomb structure, the partition wall intervals of the partition walls 1a and 1b of each partition wall group positioned in parallel are varied stepwise in at least a part of the cell structure section 3, and all the partition walls 1a and 1b have such a ratio of the cell side length to the partition wall thickness that the partition wall can withstand pressure during canning. The honeycomb structure has increased isostatic strength and thermal shock resistance and can be manufactured at low cost.