Honeycomb Filter Trapping Layer Structure Against Peeling and Pressure Loss
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Solution Overview
Problem
Existing honeycomb filters face issues with trapping layers peeling off due to stresses like vibration and thermal shock, despite improvements in trapping performance leading to increased pressure loss.
Innovation Solution
A honeycomb filter design with a trapping layer composed of non-oxide particles bonded via an oxide, where the thickness of the oxide satisfies a specific relation (R≤1.0609e^(4.7057×T), enhancing bonding strength and resistance to stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of partition wall is increased or pore size is reduced to improve trapping performance, then trapping efficiency is improved, but pressure loss increases due to PM clogging in pores
Solution Approach 1:
The partition wall is segmented into two functional layers: a porous partition wall for structural support and gas flow, and a separate trapping layer with finer pores for PM capture. This segmentation allows each layer to optimize its function without the trade-off present in single-layer designs.
Solution Approach 2:
The trapping layer is applied locally on the inner surface of the partition wall in the inflow cell region, where PM concentration is highest. This localized application provides enhanced trapping performance where needed most while minimizing overall pressure loss.
2Reliability
If heat treatment is performed to bond membrane material to form trapping layer, then trapping performance is improved, but the bonding site structure is insufficient to withstand vibration and thermal shock loads
Solution Approach 1:
The oxide layer thickness is controlled within a specific range (0.03 μm to 0.2 μm) to optimize both bonding strength and resistance to thermal shock. This parameter optimization ensures the bonding site can withstand various loads while maintaining trapping performance.
Solution Approach 2:
The bonding site is formed as a composite structure consisting of oxide and non-oxide components. This composite material structure provides enhanced mechanical strength and thermal shock resistance compared to a single-material bonding layer.
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 design effectively prevents the trapping layer from peeling off, maintaining excellent trapping performance while minimizing pressure loss under stressful conditions.
Implementation Method 1
a trapping layer for trapping particulate matter in exhaust gas on the inner surface of a partition wall surrounding an inflow cell, the trapping layer being a porous layer in which a plurality of non-oxide particles are bonded via an oxide
Data Source
AI summary
A honeycomb filter includes a honeycomb structure having a porous partition wall disposed to surround a plurality of cells and a plugging portion provided to seal either one end of the cells, wherein the cells having the plugging portion at ends on the outflow end face side and open on the inflow end face side are inflow cells, the honeycomb structure further includes a trapping layer for trapping particulate matter in exhaust gas on the inner surface of the partition wall surrounding the inflow cells, the trapping layer is a porous layer in which a plurality of non-oxide particles are bonded via an oxide, a thickness of the oxide that bonds adjacent non-oxide particles is 0.077 μm or more, and when an average particle diameter of the non-oxide particles constituting the trapping layer is R(μm) and a thickness of the oxide is T(μm), a relation of R≤1.0609e{circumflex over ( )} (4.7057×T) is satisfied.