Honeycomb Filter Catalyst Depth for Soot Peeling
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Solution Overview
Problem
Conventional honeycomb filters used in diesel particulate filters face issues with soot clogging due to peeling off from the partition wall, leading to reduced purification efficiency and increased pressure loss, especially when loaded with catalysts for continuous regeneration.
Innovation Solution
A honeycomb filter design with a pillar-shaped structure, where the partition wall loading of the exhaust-gas purifying catalyst is strategically controlled, with a higher loading on outflow cells and minimal loading on inflow cells, preventing soot peeling and maintaining regeneration efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If catalyst is loaded on the partition wall surface for continuous regeneration, then regeneration efficiency is improved, but soot peeling off and cell clogging occurs
Solution Approach 1:
The patent applies local quality by creating a catalyst-loaded layer only in the deep interior region of the partition wall (at a depth of 5 μm or more from the surface), while keeping the surface region (0-5 μm depth) free of catalyst. This localized catalyst placement enables continuous regeneration through the deep soot layer without causing surface soot peeling, as the catalyst does not directly contact the soot at the partition wall surface.
2Reliability
If catalyst is loaded deeply in the partition wall, then soot peeling is suppressed, but regeneration efficiency may decrease
Solution Approach 1:
The patent transitions from conventional surface-level catalyst loading to deep interior catalyst loading by introducing a depth dimension parameter. The catalyst is placed at a depth of 5 μm or more from the partition wall surface, utilizing the third dimension (depth) to resolve the contradiction between soot peeling prevention and regeneration efficiency. This dimensional shift allows the catalyst to burn soot effectively without causing surface peeling.
3Productivity
If catalyst loading area ratio on inflow cell partition wall is high, then purification efficiency is improved, but pressure loss increases due to soot clogging
Solution Approach 1:
The patent applies local quality by controlling the catalyst loading area ratio on the partition wall defining inflow cells to be 10% or less. This limited catalyst placement prevents excessive soot accumulation and peeling at the inflow end, thereby reducing cell clogging and pressure loss while maintaining sufficient purification efficiency through the deep interior catalyst loading in outflow 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
Effectively suppresses soot peeling and clogging, maintaining purification efficiency and preventing pressure loss increases, ensuring continuous effective regeneration.
Implementation Method 1
continuous regeneration with the catalyst loaded at the partition wall burns the soot accumulated on the surface of the partition wall
Data Source
AI summary
A honeycomb filter includes a pillar-shaped honeycomb structure body having a porous partition wall disposed to surround a plurality of cells and a plugging portion. The partition wall defining outflow cells includes an exhaust-gas purifying catalyst at least at a part of a region of 0 to 80% of a thickness of the partition wall and includes a portion that does not include the exhaust-gas purifying catalyst in a region of exceeding 80% and being 100% or less of the thickness of the partition wall, and the partition wall defining the inflow cells is not loaded with the exhaust-gas purifying catalyst on the surface, or is loaded with the exhaust-gas purifying catalyst so that a percentage of a ratio of an area of a range loaded with the exhaust-gas purifying catalyst to a surface area of the partition wall defining the inflow cells is 10% or less.