Segmented Particulate Filter Coating for PM Collection and Pressure Loss
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Solution Overview
Problem
Existing particulate filters with a wall-flow structure face challenges in achieving high levels of both PM collection performance and pressure loss suppression performance, as increased PM accumulation leads to clogging and reduced gas distributability.
Innovation Solution
The particulate filter is designed with a base material having a wall-flow structure and wash-coating layers with distinct regions: an inlet layer with no noble metal catalyst in the upstream region for enhanced PM collection and an outlet layer with a noble metal catalyst in the downstream region for improved gas distributability and pressure loss suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a noble metal catalyst is supported on the entire wash-coating layer to promote PM combustion, then pressure loss suppression is improved, but PM collection performance deteriorates due to reduced PM accumulation
Solution Approach 1:
The wash-coating layer is divided into two distinct regions: an upstream region (inlet side) without noble metal catalyst for PM accumulation, and a downstream region (outlet side) with noble metal catalyst for PM combustion. This segmentation allows each region to perform its specific function optimally without interfering with the other
Solution Approach 2:
Different functional properties are assigned to different locations within the filter. The upstream region has high PM collection capability (no catalyst), while the downstream region has high PM combustion capability (with catalyst). This local differentiation resolves the contradiction by allowing PM to accumulate in the upstream region without catalyst interference, then combust in the downstream region to maintain gas distributability
2Quantity of substance
If the pore size of partition walls is reduced to enhance PM collection performance, then PM collection efficiency is improved, but gas distributability deteriorates leading to increased pressure loss
Solution Approach 1:
The filter is segmented into an upstream region for PM collection and a downstream region for gas distribution and PM combustion. This allows small pore sizes in the upstream region to maximize PM collection while the downstream region with catalyst maintains gas distributability through combustion-induced pore clearing
Solution Approach 2:
The potential harm of small pore sizes causing clogging and reduced gas distributability is converted into a benefit through the noble metal catalyst. The catalyst promotes PM combustion that clears the pores, transforming the clogging problem into an self-cleaning mechanism that maintains gas flow while preserving high PM collection performance
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 configuration allows for high PM collection performance in the initial stage of operation and effective pressure loss suppression in the intermediate stage, achieving a balance between PM collection efficiency and pressure loss management.
Implementation Method 1
PM is collected in pores having small pore size by priority and that the pore size of partition walls is reduced by an increase in PM accumulation amount
Implementation Method 2
An exhaust gas supplied to the wall flow filter flows into the inlet cells, passes through partition walls of a porous material, and then is discharged to the outside of the filter through the outlet cells. In this process, PM in the exhaust gas is collected in pores of the partition walls
Implementation Method 3
a noble metal catalyst for promoting oxidation (combustion) of PM accumulated in pores is supported on a wash-coating layer
Implementation Method 4
a noble metal catalyst for promoting oxidation (combustion) of PM accumulated in pores
Data Source
AI summary
A particulate filter includes a base material having a wall-flow structure including porous partition walls partitioning inlet and outlet cells, and wash-coating layers held inside partition walls. The wash-coating layers include inlet layers each formed from vicinity of an end portion at exhaust gas inflow side to have predetermined length and thickness and outlet layers each formed from vicinity of end portion at exhaust gas outflow side to have a predetermined length and thickness. The inlet and the outlet layers partially overlap with each other. Inlet layers of particulate filter contain substantially no noble metal catalyst, and outlet layers contain noble metal catalyst. Accordingly, PM collection performance can be easily enhanced in inlet region, and high gas distributability (pressure loss suppression performance) can be maintained in outlet region. Accordingly, it is possible to provide particulate filter capable of achieving high levels of PM collection performance and pressure loss suppression performance.