Wall-flow filter with pore-deposited powder aerosol
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Solution Overview
Problem
Existing particulate filters for internal combustion engines face challenges in achieving high filtration efficiency while minimizing exhaust-gas back pressure, which is crucial for meeting emission standards and maintaining engine performance.
Innovation Solution
A wall-flow filter is treated with a dry powder-gas aerosol, where the powder is deposited within the filter's pores rather than forming a contiguous layer on the walls, creating a concentration gradient that enhances filtration efficiency while keeping back pressure low by ensuring the powder fills only a portion of the pores, typically less than 50 g/l, and is designed to optimize the balance between filtration and back pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a powder coating is applied to the filter walls to increase filtration efficiency, then filtration efficiency is improved, but exhaust-gas back pressure increases
Solution Approach 1:
The patent applies a porous powder coating (metal oxide particles with 0.1-5 μm diameter) to the filter walls. The coating maintains porosity rather than forming a dense layer, allowing exhaust gases to pass through while still capturing particulates. This resolves the contradiction by providing filtration enhancement without creating excessive flow resistance.
Solution Approach 2:
The powder coating is applied selectively to specific regions of the filter walls, particularly concentrating on the inlet side where particulate capture is most critical. This localized application provides enhanced filtration efficiency where needed while minimizing overall back pressure increase across the entire filter structure.
2Reliability
If the powder fills more of the pores to increase filtration efficiency, then filtration efficiency is improved, but the amount of powder required increases
Solution Approach 1:
The patent applies powder at a controlled loading level (0.5-50 g/l, preferably 1-20 g/l) that partially fills the pores rather than completely saturating them. This partial filling approach achieves sufficient filtration efficiency improvement while avoiding excessive powder consumption and the associated costs and processing complexity.
Solution Approach 2:
The patent optimizes powder particle size (0.1-5 μm diameter) to match the pore structure of the filter walls. This parameter optimization ensures that the powder effectively fills and modifies the pore architecture for enhanced filtration without requiring excessive amounts of material.
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 results in a significant increase in filtration efficiency, often by 20% or more, with a moderate increase in exhaust-gas back pressure, effectively addressing the need for improved particulate filtration without compromising engine performance.
Implementation Method 1
a powder-gas aerosol is impinged on the input side of a wall-flow filter, by which the powder is deposited in the pores of the filter walls
Data Source
AI summary
The present invention relates to a wall-flow filter, to a method for the production and the use thereof in order to reduce harmful exhaust gases of an internal combustion engine. The wall-flow filter was produced by applying a powder-gas aerosol to the filter, whereby the powder was deposited in the pores of the wall-flow filter.