Catalytically Active Wall Flow Filters with Segmented Coating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wall flow filters face challenges in achieving optimal performance in the requirement triangle of catalytic activity, filtration efficiency, and exhaust back pressure, particularly in stoichiometrically burning spark ignition engines.
Innovation Solution
A method for producing catalytically coated ceramic wall flow filters involves introducing an excess coating suspension, reversing the pressure difference to remove excess, and then introducing a second coating suspension without excess, allowing for the creation of filters with optimized filtration efficiency, reduced exhaust back pressure, and sufficient catalytic activity by controlling the distribution of catalytically active materials within the filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wall flow filter is coated with catalytically active material to achieve sufficient catalytic activity, then catalytic activity is improved, but exhaust back pressure increases
Solution Approach 1:
The filter is divided into different zones with varying catalytic material distribution. The inlet side has a first catalytic material distribution while the outlet side has a second catalytic material distribution, creating local quality differences that optimize both catalytic activity and back pressure characteristics in different regions of the filter
Solution Approach 2:
The catalytic coating is segmented into at least two different zones along the flow direction. This segmentation allows each zone to have optimized catalytic material content and distribution, balancing the trade-off between catalytic activity and back pressure by having different material densities in different sections
2Reliability
If the filter walls are made highly porous to improve particle filtration efficiency, then filtration efficiency is improved, but structural strength decreases
Solution Approach 1:
The filter substrate is made from cordierite ceramic material with controlled porosity of 40-60%. This porous structure enables effective particle filtration while the ceramic material itself provides the necessary structural strength to maintain integrity under operating conditions
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 method results in wall flow filters with improved filtration efficiency, reduced exhaust back pressure, and enhanced catalytic activity, making them suitable for various exhaust gas treatment applications.
Implementation Method 1
an excess of a first coating suspension is introduced into the first end face by applying a pressure difference via the wall flow filter
Implementation Method 2
with a pressure difference reversal, an excess of the first coating suspension is removed from the wall flow filter
Implementation Method 3
The catalyst promotes the chemical reaction of various exhaust gas components to form harmless products, such as carbon dioxide and water
Implementation Method 4
The particles are retained when the exhaust gas passes through the wall
Data Source
AI summary
The present invention relates to a wall flow filter, to a method for the production and the use of the filter for reducing harmful exhaust gases of an internal combustion engine. Particle filters are commonly used for filtering exhaust gases from a combustion process. Also disclosed are novel filter substrates and their specific use in exhaust gas aftertreatment.