Wall Flow Honeycomb Filter Coating Uniformity
Solution Overview
Problem
Existing wall flow filters face challenges in maintaining uniform coating depositions and controlling pressure drop variability during emissions treatment, particularly in gasoline particulate filters used in conjunction with gasoline direct injection engines, which emit more particulates than conventional engines.
Innovation Solution
The implementation of a plugged honeycomb filter body with intersecting porous walls, where a hydrophobic material is applied to one side and a catalytic material to the opposite side, followed by removal of the hydrophobic material during a calcining process, to create a uniform and predictable coating deposition and reduce pressure drop variability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hydrophobic material is applied to one side of porous ceramic base portions and catalytic material to the opposite side, then uniform coating deposition is achieved and pressure drop variability is reduced, but the manufacturing process complexity increases
Solution Approach 1:
The honeycomb filter body is segmented into treated sides (with hydrophobic material) and non-treated sides (with catalytic material), allowing different materials to be applied to different regions. This segmentation enables precise control over coating deposition uniformity while managing process complexity through systematic material placement
Solution Approach 2:
The hydrophobic material serves as an intermediary layer applied to one side of the porous ceramic base portions before catalytic material application. This intermediary layer prevents washcoat penetration into treated regions, ensuring uniform coating deposition and reducing pressure drop variability
2Reliability
If washcoat is applied to catalytic material, then catalytic activity is enhanced, but pressure drop increases due to washcoat penetration into porous structure
Solution Approach 1:
The hydrophobic material is applied preliminarily to treated sides before catalytic material deposition. This preliminary application creates a protective barrier that prevents washcoat penetration into the porous ceramic structure, thereby maintaining low pressure drop while still allowing catalytic activity to function effectively
Solution Approach 2:
Different regions of the porous ceramic base portions are given different properties: treated sides have hydrophobic material for washcoat prevention, while non-treated sides have catalytic material for emissions treatment. This local differentiation optimizes both catalytic activity and pressure drop characteristics
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 approach ensures high permeability and uniformity of the coating process, maintaining the filter's performance by preventing washcoat penetration into treated regions and preserving the porous structure, thereby enhancing filtration efficiency and reducing pressure drop.
Implementation Method 1
treated sides comprising hydrophobic material deposits disposed at one of the inlet sides or the outlet sides of the porous ceramic base portions
Implementation Method 2
non-treated sides comprising a catalytic material disposed at opposite sides of the porous ceramic base portions
Implementation Method 3
exhaust gas to be filtered enters inlet cells and passes through the cell walls to exit the filter via outlet channels, with the particulates being trapped on or within the inlet cell walls
Data Source
AI summary
Method of making and filtration article comprising a plugged honeycomb filter body comprising: intersecting porous walls extending an axial length in an axial direction from a proximal end to a distal end of the honeycomb filter body and defining a plurality of axial channels comprised of inlet channels, which are plugged at the distal end of the plugged honeycomb filter body, and outlet channels, which are plugged at the proximal end of the plugged honeycomb filter body, the porous walls comprising: porous ceramic base portions with a plurality of pores and an average thickness and having inlet sides and outlet sides; inlet surfaces defining the inlet channels; outlet surfaces defining the outlet channels; and treated sides comprising hydrophobic material deposits disposed at one of the inlet sides or the outlet sides of the porous ceramic base portions.