Radial Washcoat Distribution in Particulate Filters for Low Backpressure
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Solution Overview
Problem
Existing particulate filters for gasoline engines face challenges in achieving high filtration efficiency while maintaining low backpressure, especially under stringent emission standards like China 6, due to the finer and lesser quantities of particulates produced by gasoline engines, which lack the soot cake formation seen in diesel engines.
Innovation Solution
A particulate filter with a centralized-distributed functional material layer in the radial direction, optimized to have a specific volume and weight percentage of inorganic materials, combined with a catalytic washcoat, to enhance filtration efficiency and reduce backpressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a higher washcoat loading is used to meet fresh filtration efficiency requirements, then filtration efficiency is improved, but pressure drop across the filter increases
Solution Approach 1:
The patent applies different washcoat loadings to different radial regions of the filter. The central region (within radius R1) has a higher washcoat loading (G1) to provide sufficient filtration efficiency, while the outer region (between radius R1 and R2) has a lower washcoat loading (G2) to reduce pressure drop. This local differentiation resolves the contradiction by optimizing each region's contribution to filtration while minimizing overall flow resistance.
2Reliability
If a higher washcoat loading is used to achieve high filtration efficiency for gasoline engines, then fresh filtration efficiency is improved, but backpressure increases
Solution Approach 1:
The patent implements local quality by specifying different washcoat loadings for different radial positions. The central region (radius ≤ R1) receives a higher washcoat loading (G1) to ensure adequate filtration efficiency, while the outer region (R1 < radius ≤ R2) receives a lower washcoat loading (G2) to minimize backpressure. This spatial differentiation allows the filter to meet fresh filtration efficiency requirements without excessive backpressure penalty.
3Ease of manufacture
If the functional material layer is uniformly distributed, then manufacturing is simplified, but filtration efficiency and backpressure performance are compromised
Solution Approach 1:
The patent specifies a non-uniform washcoat distribution with different loadings in different radial regions, which requires more complex manufacturing processes such as zoned coating or multi-step application. However, this complexity is justified by the significant improvement in performance, achieving both high filtration efficiency and acceptable backpressure characteristics that cannot be obtained with uniform distribution.
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 filter achieves excellent filtration efficiency with low backpressure, meeting stringent emission standards by effectively capturing particulates and reducing pressure drop across the engine.
Implementation Method 1
The wall-flow filter is designed to provide for nearly complete filtration of soot without significantly hindering the exhaust flow
Implementation Method 2
passing the PM-containing exhaust gas through a particulate filter
Implementation Method 3
combined with a catalytic washcoat, to enhance filtration efficiency and reduce backpressure
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3
AI summary
The disclosure relates to a particulate filter for the treatment of exhaust gas from an internal combustion engine, wherein the particulate filter comprises a functional material layer, and the amount of the functional material layer in the region which is around the whole central axis of the particulate filter and accounts for 11.1 vol. % of the total volume of the particulate filter, is in the range from 13 to 40 wt.%, based on the total weight of the functional material layer, relates to the process for preparing the particulate filter and relates to a method for the treatment of exhaust gas from an internal combustion engine. The particulate filter according to the present invention has a centralized-distributed functional material layer in the radial direction, shows excellent filtration efficiency and low backpressure.