Dual Particulate Filter with Segmented Channels
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Solution Overview
Problem
Conventional exhaust treatment systems for internal combustion engines are large and costly due to multiple separate modules, and combined DPF and SCR modules face clogging issues due to competition for NO2, necessitating active regeneration, which increases size and cost and has drawbacks like increased fuel consumption and emissions.
Innovation Solution
A dual-particulate filter system where the first filter with an oxidation catalyst filters a portion of the exhaust stream and converts NO to NO2, while the second filter uses the generated NO2 for passive regeneration, reducing soot accumulation and eliminating the need for separate DOC and active regeneration devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple separate exhaust treatment modules (DOC, DPF, SCR) are used, then treatment effectiveness is improved, but system size and cost increase
Solution Approach 1:
The patent combines the DOC and DPF functions into a single integrated filter assembly. The filter body contains both oxidation catalyst coating (for DOC function) and wall-flow channels (for DPF function), eliminating the need for separate modules and reducing overall system size while maintaining treatment effectiveness.
Solution Approach 2:
The integrated filter assembly performs multiple functions simultaneously: it oxidizes NO to NO2 (DOC function), traps particulate matter (DPF function), and enables passive regeneration through the interaction of NO2 with trapped soot. This multi-functionality in a single component reduces system complexity and space requirements.
2Volume of stationary object
If combined DPF and SCR module is used, then system size is reduced, but clogging occurs due to competition for NO2
Solution Approach 1:
The patent segments the filter channels into two distinct types: wall-flow channels for trapping particulate matter and flow-through channels for allowing exhaust gas to pass. This segmentation prevents competition for NO2 between DPF and SCR functions, as the SCR catalyst is positioned downstream where regenerated exhaust flows through the flow-through channels, while wall-flow channels are dedicated to particle trapping and passive regeneration.
Solution Approach 2:
The patent introduces an intermediary mechanism where NO2 generated in the wall-flow channels during passive regeneration is transported through the filter structure to the downstream SCR catalyst via the flow-through channels. This intermediary transport path ensures that NO2 is available for both passive regeneration in the DPF section and for enhancing SCR conversion efficiency downstream, eliminating the competition problem.
3Reliability
If active regeneration is implemented, then soot accumulation is removed, but fuel consumption and emissions increase
Solution Approach 1:
The patent implements passive regeneration that operates automatically using the exhaust gas itself as the regenerating agent. NO2 present in the exhaust stream (or generated by the oxidation catalyst) reacts with trapped soot in the wall-flow channels at operating temperatures, eliminating the need for external fuel injection or active heating systems required by conventional active regeneration methods.
Solution Approach 2:
The patent converts the typically harmful NO2 component in exhaust gas into a beneficial regenerating agent. Instead of treating NO2 as a pollutant to be eliminated, the system utilizes its strong oxidizing properties to burn off trapped soot particles, transforming a harmful substance into a useful resource for maintaining filter 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 reduces system size and cost, maintains continuous passive regeneration, and lowers the balance point of the filters, preventing clogging and minimizing fuel consumption and emissions.
Implementation Method 1
The first filter body defines a first plurality of flow-through channels between the first inlet side and the first outlet side and a first plurality of wall-flow channels between the first inlet side and the first outlet side
Implementation Method 2
combines a gaseous or liquid reductant (e.g., urea or ammonia) with the exhaust stream and then reacts the combined stream with a catalyst to convert NOx in the exhaust stream into diatomic nitrogen (N2) and water (H2O)
Implementation Method 3
The first filter body defines a first plurality of flow-through channels between the first inlet side and the first outlet side and a first plurality of wall-flow channels between the first inlet side and the first outlet side
Data Source
AI summary
In one aspect, an exhaust treatment system includes a first particulate filter that has an oxidation catalyst and receives an exhaust stream from an engine. The first particulate filter has a first filter body that defines a plurality of flow-through channels, each open on the inlet and outlet sides of the first filter body. The first filter body also defines a plurality of wall-flow channels, each open on one of the inlet and outlet sides and closed on the other of the inlet and outlet sides. The system also has a second particulate filter that receives the exhaust stream from the first particulate filter. The second particulate filter has a second filter body that defines a plurality of wall-flow channels, each open on one of the inlet and outlet sides of the second particulate filter and closed on the other of the inlet and outlet sides of the second particulate filter.