Honeycomb Filter Trapping Layer Thickness Optimization
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Solution Overview
Problem
Honeycomb filters face challenges in efficiently trapping and removing solid components from exhaust gases, leading to increased pressure loss and temperature rises due to uneven deposition and clogging, particularly in the downstream region, as existing designs struggle to balance permeation resistance and trapping efficiency.
Innovation Solution
A honeycomb filter design with specific thickness ratios and hydraulic diameters for the partition and trapping layers, along with the use of inorganic materials and a catalyst, is employed to optimize the trapping and removal of solid components, reducing deposition in the downstream region and maintaining low pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a trapping layer with smaller average pore size than the partition is formed on the partition portion, then the capacity to trap solid components is improved, but the permeation resistance of the partition increases and solid components deposit excessively in the downstream region
Solution Approach 1:
The patent applies local quality by creating different trapping layer thicknesses at different axial positions. The trapping layer has a smaller thickness in the axial central region (where permeation resistance is critical) and a larger thickness in the axial upstream and downstream regions (where trapping capacity is needed). This spatial variation in thickness resolves the contradiction between trapping efficiency and permeation resistance.
Solution Approach 2:
The patent introduces axial position as an additional dimension for optimizing trapping layer thickness. Instead of using a uniform thickness throughout, the thickness varies along the axial direction, with specific thickness ratios defined between central region and upstream/downstream regions. This dimensional approach allows simultaneous optimization of trapping capacity and permeation resistance.
2Reliability
If the trapping layer thickness is increased to improve trapping capacity, then more solid components are trapped, but pressure loss increases due to excessive deposition and clogging
Solution Approach 1:
The patent applies local quality by creating different trapping layer thicknesses at different axial positions. The trapping layer has a smaller thickness in the axial central region (where permeation resistance is critical) and a larger thickness in the axial upstream and downstream regions (where trapping capacity is needed). This spatial variation in thickness resolves the contradiction between trapping efficiency and permeation resistance.
Solution Approach 2:
The patent introduces axial position as an additional dimension for optimizing trapping layer thickness. Instead of using a uniform thickness throughout, the thickness varies along the axial direction, with specific thickness ratios defined between central region and upstream/downstream regions. This dimensional approach allows simultaneous optimization of trapping capacity and permeation resistance.
3Stress or pressure
If the trapping layer thickness is decreased in the central region to reduce permeation resistance, then exhaust gas permeability increases, but the trapping capacity in that region decreases
Solution Approach 1:
The patent applies local quality by creating different trapping layer thicknesses at different axial positions. The trapping layer has a smaller thickness in the axial central region (where permeation resistance is critical) and a larger thickness in the axial upstream and downstream regions (where trapping capacity is needed). This spatial variation in thickness resolves the contradiction between trapping efficiency and permeation resistance.
Solution Approach 2:
The patent introduces axial position as an additional dimension for optimizing trapping layer thickness. Instead of using a uniform thickness throughout, the thickness varies along the axial direction, with specific thickness ratios defined between central region and upstream/downstream regions. This dimensional approach allows simultaneous optimization of trapping capacity and permeation 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
The optimized design enhances the trapping efficiency and regeneration limit, decreases pressure loss, and prevents uneven distribution of solid components, thereby improving the filter's performance and extending the interval between regeneration cycles.
Implementation Method 1
a trapping layer for trapping and removing particulate matter (hereinafter also referred to as PM) contained in an exhaust gas formed on the partition portion
Implementation Method 2
the capacity to trap and remove solid components contained in the fluid can be improved
Implementation Method 3
PM is removed by combustion
Data Source
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AI summary
In a honeycomb filter 20, a partition portion 22 has a thickness tp of 150 µm or more and 460 µm or less, a trapping layer constituting a trapping layer 24 has an average thickness tAve of 5 µm or more and 80 µm or less, the film thickness ratio Y1 of a downstream thickness t1 to an up- and mid-stream thickness thm, which is a mean value of an upstream region and a midstream region of the trapping layer 24 of the honeycomb filter 20, satisfies the relationship of the formula (1), the film thickness ratio Y2 of the maximum thickness tmax of a trapping layer of the trapping layer 24 to the average thickness tAve of the trapping layer satisfies the relationship of the formula (2), and a cell 23 has a hydraulic diameter HDin satisfying the relationship of the formula (3).