Honeycomb Filter Porous Body Surface Layer Optimization
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Solution Overview
Problem
Existing porous bodies used in honeycomb filters for exhaust gas cleaning have limited trapping capability and increased pressure loss after particulate matter (PM) deposition, as larger surface layer thicknesses allow PM to penetrate deeper into the filter, reducing trapping efficiency and increasing pressure loss.
Innovation Solution
A method involving three-dimensional scanning to determine the surface layer thickness and porosity of the porous body, where the surface layer thickness is optimized to a small value satisfying the formula P≥0.54 Ts or P≥0.63 Ts, to enhance trapping capability and reduce pressure loss, by identifying surface layer straight-pore voxels and deriving the surface layer thickness using imaginary reference planes with specific opening ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the surface layer thickness is increased to allow deeper PM penetration, then the trapping capability is improved, but the pressure loss after PM deposition increases
Solution Approach 1:
The patent applies local quality by creating a surface layer with specific porosity and thickness characteristics that differ from the inner layer. The surface layer has optimized pore structure (porosity P and thickness Ts satisfying P≥0.54Ts) to enhance PM trapping at the inlet, while the inner layer provides additional filtration capacity. This localized structural differentiation allows the surface layer to capture PM efficiently before it penetrates deeper, thereby improving trapping capability while controlling pressure loss.
Solution Approach 2:
The patent utilizes parameter changes by establishing a specific quantitative relationship between surface layer porosity P and thickness Ts (P≥0.54Ts). By optimizing these parameters within this relationship, the patent achieves the desired balance between trapping capability and pressure loss. The formula provides a design guideline that allows adjustment of both parameters while maintaining optimal performance, enabling flexible adaptation to different application requirements.
2Reliability
If the surface layer thickness is increased to extend straight pores deeper, then the filtering capacity is improved, but the PM deposition amount in the surface layer increases leading to higher pressure loss
Solution Approach 1:
The patent applies segmentation by dividing the porous body into distinct surface layer and inner layer regions with different structural characteristics. The surface layer (with thickness Ts and porosity P satisfying P≥0.54Ts) is segmented from the inner layer, with the surface layer containing straight pores extending from the inlet for enhanced PM capture. This segmentation allows each layer to perform its specific function: the surface layer for initial PM trapping and the inner layer for additional filtration, thereby improving overall filtering capacity while controlling PM deposition in the surface layer.
Solution Approach 2:
The patent applies local quality by giving the surface layer distinct structural properties (specific porosity P and thickness Ts relationship) compared to the inner layer. The surface layer is designed with optimized local characteristics to maximize PM trapping efficiency at the inlet region, while the inner layer provides complementary filtration. This localized structural optimization ensures that PM deposition is distributed appropriately, preventing excessive accumulation in the surface layer and thereby controlling pressure loss.
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 optimized surface layer thickness and porosity configuration significantly increases the trapping capability of PM while minimizing pressure loss after deposition, making the porous body more effective in filtering exhaust gases.
Implementation Method 1
a porous body in a member, such as a honeycomb filter, for cleaning exhaust gas
Implementation Method 2
porous-body data in which positional information providing a position of a voxel is associated with voxel type information including information that allows determination as to whether the voxel is a spatial voxel representing a space or an object voxel representing an object is prepared through three-dimensional scanning
Data Source
AI summary
In a porous body, a surface layer thickness Ts takes a relatively small value satisfying P≥0.54 Ts (formula (1)), the surface layer thickness Ts being derived by a microstructure analysis using the porous-body data that is prepared through three-dimensional scanning of a region including a surface (inflow plane 61) of the porous body. Here, P denotes a porosity [%] of the porous body, and 0%<P<100% and 0 μm<Ts are assumed. The surface layer thickness Ts is derived as a distance in a thickness direction (X direction) between a surface-layer region start plane 92 in which a straight-pore opening ratio becomes 98% or less for the first time and a surface-layer region end plane 93 in which the straight-pore opening ratio becomes 1% or less for the first time.