Plugged Honeycomb Structure End-Surface Polishing
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Solution Overview
Problem
Conventional plugged honeycomb structures used in diesel particulate filters suffer from variations in cell lengths, leading to increased inflow resistance and soot deposition, which results in pressure loss and decreased fuel efficiency, due to surface undulations and recess portions generated during firing.
Innovation Solution
A plugged honeycomb structure with end-surface polishing in regions covering 35% or more of the total area to reduce recess portion depth and uniform cell lengths, preventing soot deposition and pressure loss increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the plugged honeycomb structure is obtained by extrusion-forming followed by firing, then the structure can be manufactured, but surface undulations are generated and cell length variations occur
Solution Approach 1:
The invention applies a smoothing treatment to the end surfaces of the honeycomb structured body before plugging the cells. This preliminary action removes surface undulations and ensures uniform cell lengths before the plugging process, preventing the generation of inflow resistance variations and soot deposition issues that would otherwise occur during firing and plugging.
2Ease of manufacture
If plugged portions are formed by charging cells with constituent material and firing, then the plugged portions are created, but recess portions (shrinkage cavities) are generated at the ends
Solution Approach 1:
The invention smooths the end surfaces of the honeycomb structured body before charging the cells with plugging material. This preliminary smoothing ensures that when the plugged portions are formed by firing, the recess portions (shrinkage cavities) are minimized or eliminated, preventing soot deposition at the ends of plugged portions and subsequent regeneration issues.
3Manufacturing precision
If cell lengths vary due to surface undulations, then inflow resistance varies among cells, but smoothing the surface requires additional processing
Solution Approach 1:
The invention incorporates a smoothing treatment as a preliminary step before plugging, which ensures uniform cell lengths and eliminates surface undulations. This single preliminary action prevents multiple subsequent problems including inflow resistance variations, soot deposition, and pressure loss, making the overall process more efficient despite the added smoothing step.
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
The smoothing treatment effectively suppresses cell clogging and pressure loss, maintaining filter layer area and fuel efficiency by reducing soot deposition and uniforming cell lengths, while preventing rapid pressure loss and fuel efficiency deterioration.
Implementation Method 1
the partition walls 7 become filter layers, and the soot in the exhaust gas is caught by the partition walls 7, and deposited on the partition walls 7
Implementation Method 2
the plugged portions 4 are usually formed by charging the cells with a constituent material of the plugged portions in a slurried state or the like, followed by firing
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
There is disclosed a plugged honeycomb structure which does not decrease an area of a filter layer, but suppresses the variations of lengths of cells and the deposition of soot at ends of plugged portions, and does not easily increase a pressure loss, when the structure is used as a filter such as a DPF. A plugged honeycomb structure 1 includes a honeycomb structured body where a plurality of cells communicating between an inlet end surface which becomes an inlet side of a fluid and an outlet end surface which becomes an outlet side of the fluid are partitioned by porous partition walls; and plugged portions to plug open frontal areas of the predetermined cells on the side of the inlet end surface and open frontal areas of the remaining cells on the side of the outlet end surface. The plugged portions are formed by charging the cells with a constituent material of the plugged portions, followed by firing, and in a region A having an area which is 35% or larger of the total area of the inlet end surface and the outlet end surface, a smoothing treatment by end-surface polishing is performed so that a depth of a recess portion generated at an end of each of the plugged portions during the firing becomes small.