Honeycomb Filter Cell Geometry for Pressure Loss and Strength
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Solution Overview
Problem
Honeycomb filters used in diesel particulate filters face issues where particulates deposited on the inflow side can close the cells, leading to increased pressure loss and structural weakness at intersection points, especially when the sectional areas of inflow-side and outflow-side cells differ, causing stress concentration and potential breakage.
Innovation Solution
A honeycomb filter design with alternately arranged cells having different sectional areas, where the ratio of hydraulic diameters is 1.2 or more, and the shape of the larger section is quadrangular with circular corner portions, maintaining a minimum thickness ratio of intersection points to partition walls between 0.7 and 1.3, preventing cell closure and ensuring high strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sectional area of the inflow-side cell is set to be different from that of the outflow-side cell to inhibit cell closure, then the pressure loss increases, but the partition wall thickness at intersection portions decreases causing structural weakness
Solution Approach 1:
The patent applies local quality by making the corner portions of the cell sectional shape circular rather than sharp-angled. This local geometric modification distributes stress more evenly at the intersection portions of partition walls, preventing stress concentration while maintaining the different sectional areas needed to inhibit cell closure. The circular corners create a gradual transition that strengthens the partition walls without compromising the flow distribution function.
Solution Approach 2:
The patent employs asymmetry by designing cells with different sectional areas at the inflow side compared to the outflow side. The inflow-side cells have larger sectional areas with circular corner portions, while outflow-side cells maintain different dimensions. This asymmetric design optimizes flow distribution to prevent particulate accumulation and cell closure at the inflow side, while the circular corners compensate for the thinned partition walls created by the area difference.
2Object-affected harmful factors
If the sectional area of inflow-side cells is increased to prevent particulate deposition and cell closure, then the pressure loss is reduced, but the partition walls become thinner and more prone to breaking
Solution Approach 1:
The circular corner portions are applied locally at the intersection portions of partition walls where stress concentration occurs. This local geometric feature strengthens the partition walls by distributing stress evenly, preventing breakage even when the overall partition wall thickness is reduced to enable larger cell sectional areas that resist particulate deposition and cell closure.
Solution Approach 2:
The patent replaces sharp corners with circular (curved) corners at the cell intersections. This curvature eliminates stress concentration points that would occur at sharp angles, allowing the partition walls to maintain strength despite being thinner. The curved geometry smoothly transitions the flow and distributes mechanical stresses, preventing partition wall breakage while enabling larger cell areas.
3Productivity
If post injection is performed to combust and remove deposited PM, then the cell closure is relieved, but stress concentrates on thinned intersection portions causing breakage
Solution Approach 1:
The circular corner portions provide localized structural reinforcement at the intersection portions of partition walls. This local geometric feature distributes stress evenly throughout the intersection area, preventing stress concentration that would occur during PM combustion and removal operations. The strengthened intersection portions can withstand the thermal and mechanical stresses of post-injection regeneration without breaking.
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 design effectively inhibits particulate deposition at the inflow side from closing the cells and maintains high strength by distributing stress evenly, reducing pressure loss and enhancing the durability of the honeycomb filter.
Implementation Method 1
the porous partition walls constituting the cells perform functions of filters by alternately plugging the cells
Implementation Method 2
at least a sectional shape of the cell having the large sectional area is a quadrangular shape whose portion corresponding to at least one corner portion is circular
Data Source
AI summary
In a honeycomb filter in which a plurality of cells are formed by porous partition walls, and a predetermined cell whose one end portion is plugged, and a remaining cell whose other end portion is plugged are alternately arranged in such a manner as to form checked patterns in the opposite end portions. In a section of the filter, a sectional area of the predetermined cell is different from that of the remaining cell, a value of a ratio of a channel hydraulic diameter of the cell having a large sectional area to that of the cell having a small sectional area is 1.2 or more, at least a sectional shape of the cell having the large sectional area is a quadrangular shape whose portion corresponding to at least one corner portion is circular, and a value of a ratio of minimum thickness of a portion (intersection portion) in which the partition walls cross one another to a thickness of each partition wall 2 is 0.7 or more and less than 1.3. The honeycomb filter is capable of inhibiting a fluid inflow-side end face (opening of an inflow-side cell) from being closed by particulates and the like, and maintaining high strength.