Diesel Particulate Filter Bridge Network for Backpressure Reduction
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Solution Overview
Problem
Current Diesel particulate filters face challenges in maintaining filtration efficiency, especially after regeneration, due to the passage of small particles and increased backpressure, which does not meet the stringent particle number emission limits, and similar issues exist with gasoline engines where high temperatures prevent particulate cake formation.
Innovation Solution
A porous substrate filter with a bridge network of refractory material deposited as an aerosol on the inlet surfaces, forming a bridge network over the pores, which enhances filtration efficiency while reducing backpressure by allowing gas flow and facilitating particulate cake formation without the need for high temperature processing or interfering with catalyst application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional porous ceramic filters are used, then filtration efficiency is achieved through particulate cake formation, but backpressure increases excessively and small particles pass through unfiltered
Solution Approach 1:
The patent applies a surface layer with different pore characteristics (smaller mean pore size of 0.5-5 μm) specifically at the inlet surfaces where particulate cake forms, while the bulk filter structure maintains larger pores (10-50 μm) for gas flow. This local differentiation allows efficient particle capture at the cake formation zone without creating excessive backpressure throughout the entire filter structure.
Solution Approach 2:
The filter combines multiple materials with complementary properties: porous ceramic substrate for structural integrity and gas flow, and a surface layer of finer porous material (such as alumina, silica, or zeolite) for enhanced particle capture. This composite structure achieves superior filtration efficiency while maintaining acceptable backpressure levels.
2Reliability
If high temperature regeneration is applied to remove trapped PM, then filtration efficiency is restored, but small particles are released into the environment
Solution Approach 1:
The patent modifies the physical parameters of the filter surface by introducing a surface layer with smaller mean pore size (0.5-5 μm) compared to the bulk structure (10-50 μm). This parameter change enhances the capture of small particles during normal operation, reducing the load on the regeneration process and minimizing particle release during temperature cycles.
3Reliability
If pore size is reduced to capture smaller particles, then filtration efficiency improves, but gas flow resistance increases
Solution Approach 1:
The patent implements different pore sizes in different regions: the surface layer at inlet surfaces has smaller pores (0.5-5 μm) for particle capture, while the bulk filter structure maintains larger pores (10-50 μm) for gas flow. This spatial differentiation of pore characteristics allows simultaneous optimization of filtration efficiency and gas flow throughput.
Solution Approach 2:
The filter structure is segmented into two functional zones with distinct pore characteristics. The surface layer handles particle capture with fine pores, while the bulk substrate handles gas flow with coarse pores. This segmentation allows each zone to be optimized for its specific function without compromising the other.
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 improved filtration efficiency and lower backpressure across all operating conditions, maintaining high performance during particulate matter loading and regeneration cycles, and can be used in both Diesel and gasoline engines, effectively addressing the limitations of traditional filters.
Implementation Method 1
A porous substrate filter with a bridge network of refractory material deposited as an aerosol on the inlet surfaces
Implementation Method 2
refractory material deposited as an aerosol on the inlet surfaces, forming a bridge network over the pores
Implementation Method 3
filter for filtering particulate matter from exhaust gas emitted from a lean-burn internal combustion engine
Implementation Method 4
porous substrate having inlet surfaces and outlet surfaces, wherein the inlet surfaces are separated from the outlet surfaces by a porous structure containing pores
Data Source
AI summary
A method of making a filter for filtering particulate matter from exhaust gas emitted from a lean-burn internal combustion engine, which filter comprising a porous substrate having inlet surfaces and outlet surfaces, wherein the inlet surfaces are separated from the outlet surfaces by a porous structure containing pores of a first mean pore size, wherein the inlet surfaces comprise a bridge network comprising interconnected particles of refractory material over the pores of the porous structure, which method comprising the step of contacting inlet surfaces of the filter substrate with an aerosol comprising refractory material in dry powder form. The invention also relates to a filter obtainable by such method.