Refractory Powder Coated Exhaust Filter for Low Back Pressure
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Solution Overview
Problem
Vehicular exhaust filters face challenges in maintaining filtration efficiency over the life of the filter, particularly during initial use and regeneration, due to the buildup of particulate matter which can lead to decreased performance and increased emissions of small particles.
Innovation Solution
A vehicular exhaust filter with a porous substrate loaded with a refractory powder having a tapped density less than 0.10 g/cm3, where greater than 40% of the powder is located within the porous structure, enhancing filtration efficiency and maintaining low back pressure across various soot loadings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a ceramic wall-flow filter is used with pore sizes of 5-50 μm, then the filter structure is simple and manufacturing is easy, but the filtration efficiency for small particulate matter (10-200 nm) is insufficient
Solution Approach 1:
The patent applies porous refractory powder materials with specific pore size distributions (bimodal or multimodal) to the filter substrate. The porous structure enables efficient capture of fine particulate matter (10-200 nm) while maintaining manufacturing feasibility through coating processes on existing ceramic substrates
Solution Approach 2:
The patent creates a composite filter structure by coating refractory powder (such as alumina, silica, or titania) onto the ceramic wall-flow substrate. This composite approach combines the structural benefits of ceramic with the filtration capabilities of refractory materials, achieving both high filtration efficiency and manufacturing simplicity
2Reliability
If the filter operates continuously without regeneration, then filtration efficiency is maintained, but back pressure increases and engine performance deteriorates
Solution Approach 1:
The patent enables periodic regeneration cycles where accumulated particulate matter is burned off at elevated temperatures. The refractory powder coating facilitates this by providing catalytic surfaces and maintaining structural integrity during thermal cycling, allowing the filter to reset and maintain low back pressure while preserving filtration efficiency
Solution Approach 2:
The patent utilizes changes in operational parameters (temperature, oxygen concentration) to switch between filtration mode and regeneration mode. The refractory powder coating allows the filter to withstand and utilize these parameter changes, enabling efficient particulate oxidation during regeneration without damaging the filter structure
3Productivity
If regeneration is performed to remove trapped PM, then back pressure is reduced, but filtration efficiency decreases during and after regeneration
Solution Approach 1:
The refractory powder coating acts as a protective layer that prevents direct exposure of the ceramic substrate to high-temperature regeneration conditions and particulate matter. This pre-established protective barrier maintains filtration efficiency during regeneration by preventing damage to the underlying substrate and reducing particulate release
4Reliability
If the porous structure is loaded with soot, then filtration efficiency increases due to cake formation, but back pressure increases excessively
Solution Approach 1:
The refractory powder coating provides a controlled porous structure with specific surface area and pore size distribution that allows soot to be captured and held without forming dense cakes. The porous structure distributes particulate matter throughout the coating layer, maintaining filtration efficiency while minimizing back pressure increases
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 filtration efficiencies greater than 90% at low soot loadings and maintains a stable back pressure response, improving the filter's performance throughout its life and reducing emissions.
Implementation Method 1
a vehicular exhaust filter with a porous substrate loaded with a refractory powder... greater than 40% of the powder is located within the porous structure... enhancing filtration efficiency
Data Source
AI summary
A vehicular exhaust filter comprising a porous substrate having an inlet face and an outlet face with the porous substrate comprising inlet channels extending from the inlet face and outlet channels extending from the outlet face is disclosed. The inlet channels and the outlet channels are separated by a plurality of filter walls having a porous structure. The vehicular exhaust filter is loaded with a refractory powder having a tapped density before loading of less than 0.10 g/cm3 and the vehicular exhaust filter has a mass loading of the refractory powder of less than 10 g/l.