Honeycomb Structure Crack Resistance via Local Partition Wall Thickness
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Solution Overview
Problem
The existing honeycomb structures used in diesel particulate filters are prone to end face cracks due to thermal stress, which can lead to the separation of plugging portions and a decrease in particulate matter trapping efficiency.
Innovation Solution
A honeycomb structure design with a pillared structure body where the ratio of bending strengths between specific specimens is controlled between 1.1 to 2.0, preventing end face cracks from forming around the plugging portions and ensuring sufficient isostatic strength, using materials like cordierite and silicon carbide, and varying cell shapes and thicknesses to manage stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a plugging portion is disposed at the end face of a cell to trap particulate matter, then trapping efficiency is improved, but the plugging portion may separate from the honeycomb structure when end face cracks occur
Solution Approach 1:
The partition wall thickness is varied locally: it is thicker at the end face side and thinner at the intermediate side. This local quality change reinforces the end face area where cracks are most likely to occur and where the plugging portion is located, preventing separation while maintaining filtration efficiency
Solution Approach 2:
The partition wall thickness parameter is changed along the length of the honeycomb structure. By making the thickness vary from the end face toward the intermediate side, the structure achieves optimal strength distribution to resist thermal stress and prevent crack propagation around plugging portions
2Strength
If the partition wall thickness is increased to prevent crack propagation, then structural strength is improved, but isostatic strength may be compromised
Solution Approach 1:
The partition wall has different thicknesses at different locations: thicker at the end face for crack resistance, and thinner at the intermediate side to maintain isostatic strength. This local differentiation allows the structure to satisfy both requirements simultaneously
Solution Approach 2:
The partition wall thickness is excessive (thicker) only where needed for crack resistance at the end face, and reduced (partial action) at the intermediate side. This partial application of increased thickness prevents over-reinforcement that would compromise isostatic strength
Data Source
AI summary
A honeycomb structure includes a pillar-shaped honeycomb structure body which includes a porous partition wall 1 defining a plurality of cells, and a part of the plurality of cells is an inflow cell of which a portion at the inflow end face side is opened and a portion at the outflow end face side is provided with a plugging portion, the residual cell of the plurality of cells is an outflow cell of which a portion at the inflow end face side is provided with the plugging portion and a portion at the outflow end face side is opened, the inflow cell and the outflow cell are arranged adjacent to each other, and a value of a ratio between a bending strength of a first specimen cut out according to condition (1) and a bending strength of a second specimen cut out according to condition (2) is 1.1 to 2.0.