Exhaust Gas Purification Filter Pore Distribution
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Solution Overview
Problem
Conventional exhaust gas purification filters face challenges in achieving high NOX purification performance due to increased flow path resistance and partial thickening of the catalyst layer when supporting a NOX purification catalyst.
Innovation Solution
The exhaust gas purification filter features a honeycomb structure with partition walls that have a gas permeability coefficient of 0.35×10−12 m2 or greater, a pore volume ratio of pore diameters 9 μm or less of 25% or less, and an average pore diameter of 12 μm or greater, allowing for a thinly and widely formed catalyst layer that efficiently reduces NOX.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the partition wall has high porosity and large pore diameter to reduce pressure loss, then gas permeability is improved, but PM collection efficiency deteriorates
Solution Approach 1:
The partition wall employs a non-uniform pore diameter distribution where smaller pores (9μm or less) are strategically distributed to capture PM particles while larger pores maintain gas permeability. This local differentiation of pore sizes allows simultaneous optimization of PM collection and pressure loss reduction
Solution Approach 2:
The invention changes the pore diameter parameter from a uniform structure to a distributed structure with specific constraints (pore volume ratio of 9μm or less ≤25%, average pore diameter ≥12μm). This parameter optimization resolves the contradiction by balancing PM capture capability with gas flow resistance
2Reliability
If the catalyst layer is made thick to improve NOX purification performance, then purification efficiency is improved, but flow path resistance increases
Solution Approach 1:
The catalyst layer is applied locally on the partition wall surface rather than as a thick uniform layer. The partition wall's porous structure provides sufficient catalyst support area, allowing thin catalyst application that maintains NOX purification while minimizing flow resistance
Solution Approach 2:
The partition wall serves as a porous substrate that supports the catalyst layer. The porous structure provides large surface area for catalyst deposition, enabling effective NOX purification with minimal catalyst thickness and reduced flow path resistance
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 configuration results in high NOX reduction efficiency while minimizing pressure loss and maintaining effective PM collection efficiency, thereby enhancing the overall purification performance of the exhaust gas purification filter.
Implementation Method 1
The partition wall has a gas permeability coefficient that is equal to or greater than 0.35×10−12 m2, a pore volume ratio of pore diameters of 9 μm or less that is equal to or less than 25%, and an average pore diameter that is equal to or greater than 12 μm
Data Source
AI summary
An exhaust gas purification filter is used so as to support a NOX purification catalyst. The exhaust gas purification filter includes a honeycomb structure portion and a plug portion. The honeycomb structure portion includes a partition wall and cells. Numerous pores are formed in the partition wall. The cells are partitioned by the partition walls and form a flow path for an exhaust gas. The plug portion alternately seals an inflow end surface or an outflow end surface for the exhaust gas in the cells. The partition wall has a gas permeability coefficient that is equal to or greater than 0.35×10−12 m2, a pore volume ratio of pore diameters of 9 μm or less that is equal to or less than 25%, and an average pore diameter that is equal to or greater than 12 μm.