Particulate Filter with Upstream Catalyst Coating for Low Backpressure
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Solution Overview
Problem
Particulate filters for gasoline internal combustion engines face issues with high backpressure due to high porosity ceramic structures and catalyst material degradation during regeneration steps, leading to reduced catalytic efficiency and increased pollutant emissions.
Innovation Solution
A particulate filter with a low porosity ceramic structure and a catalyst coating applied only to the upstream portion, extending between 10mm to 80% of the filter's length, ensuring both high filtering capacity and reduced backpressure, while avoiding thermal degradation by omitting catalyst material from the downstream portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a high porosity ceramic structure is used, then the backpressure is reduced, but the filtering capacity decreases
Solution Approach 1:
The patent changes the porosity parameter of the ceramic material to a low value (less than 50%, preferably less than 40%), which is opposite to the conventional high porosity approach. This parameter change enables the ceramic structure to provide both high filtering capacity through the porous walls and acceptable backpressure characteristics through the overall filter design.
2Reliability
If a coating of catalyst material is applied to the entire filter, then the catalytic capacity is maximized, but the catalyst material degrades due to high temperatures during regeneration
Solution Approach 1:
The patent applies the catalyst material coating only to a portion of the ceramic structure, specifically the upstream portion extending for 10% to 50% of the overall filter length. This local quality approach ensures that the catalyst is positioned where it can effectively treat exhaust gases before they enter the channels, while avoiding placement in the downstream high-temperature zones where regeneration occurs, thus preventing thermal degradation.
Solution Approach 2:
The filter is segmented into different functional zones: an upstream portion with catalyst coating for catalytic conversion, and a downstream portion without catalyst for high-temperature regeneration. This segmentation allows each zone to perform its specific function optimally without interfering with the other.
3Stress or pressure
If the average pore size is increased, then the flow resistance is reduced, but the particulate removal efficiency decreases
Solution Approach 1:
The patent specifies that the average pore size of the ceramic material should be less than 15 microns, which is a relatively small pore size that enhances particulate removal efficiency through the porous walls while maintaining acceptable flow resistance through the overall filter structure design.
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 solution achieves a high filtering capacity, reduced backpressure, and maintained catalytic efficiency for pollutant reduction, while preventing catalyst material degradation, resulting in improved filtration and catalytic performance with lower upstream pressure and ash storage capacity.
Implementation Method 1
force the flow of exhaust gases entering the filter to pass from one channel to at least one other channel in order to leave the filter, flowing through the pores of the ceramic material wall defining each channel
Implementation Method 2
a structure of porous ceramic material, having a conformation elongated in a main direction, and defining a plurality of parallel channels
Implementation Method 3
a coating of catalyst material applied to said structure of ceramic material substrate
Data Source
Figure 1
AI summary
A particulate filter for a gasoline internal combustion engine comprises a structure (2) of porous ceramic material, having a conformation elongated in a main direction, and defining a plurality of parallel channels (3) extending from an upstream end (2A) to a downstream end (2B) of the structure of porous ceramic material (2), with reference to a direction of a flow of exhaust gases through said filter. The channels (3) comprise first channels only closed at their upstream end (2A) and second channels only closed at their downstream end (2B), so as to force the flow of exhaust gases entering the filter to pass from one channel (3) to at least one other channel in order to leave the filter, flowing through the pores of the ceramic material wall (W) defining each channel (3). A coating (C) of catalyst material is applied to said ceramic material structure (2), on just an upstream portion (L1) of said ceramic material structure (2), adjacent to said upstream end (2A) and extending in said main direction for a length (L1) not less than 10 mm and not more than 80% of the overall length (L) of said structure (2) of porous ceramic material, in such a way that in said upstream portion (L1) of the ceramic material structure (2), the coating of catalyst material (C) covers both said first channels and said second channels, while in the remaining portion of the ceramic material structure (2), the coating of catalyst material (C) is absent from both said first channels and from said second channels. The ratio between the amount by weight of catalyst material and the volume of the filter is less than 61 g/liter.