Bypass Flow Filter Guide Vanes Pressure Loss
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Solution Overview
Problem
Existing bypass flow filters in exhaust gas aftertreatment systems for motor vehicles face challenges in achieving high efficiency while maintaining low pressure loss and withstanding thermal and dynamic stresses, and in effectively converting and retaining pollutants, particularly particulates, to comply with future legislation.
Innovation Solution
A bypass flow filter design featuring a structured wall layer with projecting guide vanes and passages, where the passages have a narrowing cross section directed towards adjacent guide vanes, enhancing dynamic pressure reduction and even loading of the filter layer, and utilizing a metallic wall layer and catalytically active coatings for improved pollutant conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the filter layer is completely closed on alternate sides, then the filter efficiency is improved, but the pressure loss increases significantly
Solution Approach 1:
The filter body is divided into multiple channels with structured wall layers containing vanes that segment the flow path. This segmentation allows the exhaust gas to be divided into multiple streams, each passing through filter layers while maintaining bypass flow capabilities, thus improving filtration efficiency without causing excessive pressure loss in any single channel.
Solution Approach 2:
Different regions of the filter body have different structures: some channels have closed filter layers for high efficiency, while others have open bypass flow paths for low resistance. The vanes in the structured wall layers create local variations in flow characteristics, allowing each region to optimize for its specific function (filtration or bypass).
2Reliability
If the vane height is increased to improve pollutant conversion, then the filter efficiency improves, but the pressure loss increases
Solution Approach 1:
The vanes are designed with specific height ratios (100%-60% of structure height) and orientations that dynamically interact with the exhaust gas flow. The oblique positioning of guide vanes creates dynamic flow patterns that enhance pollutant conversion while the bypass flow capability allows the system to adapt to varying load conditions, maintaining low pressure loss even when vane height is optimized for conversion.
Solution Approach 2:
The patent optimizes the vane height parameter within a specific range (100%-60% of structure height) rather than maximizing it completely. This parameter optimization, combined with the freedom of flow parameter (at least 20% bypass capability), creates a balanced design where pollutant conversion is improved without excessive pressure loss.
3Loss of energy
If the filter body is designed as an open system with bypass flow, then the pressure loss is reduced, but the filter efficiency decreases
Solution Approach 1:
The structured wall layers with vanes serve multiple functions simultaneously: they guide the exhaust gas flow, create pressure differential for filtration, enable bypass flow for low resistance, and enhance pollutant conversion through oblique positioning. This multi-functionality allows the open system to maintain both low pressure loss and high filter efficiency.
Solution Approach 2:
The vanes in the structured wall layers act as intermediaries between the exhaust gas flow and the filter layers. They redirect and condition the flow before it reaches the filter media, enhancing the interaction between gas and filter material, thus improving efficiency while maintaining the benefits of the open bypass system.
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 design increases filter efficiency by nearly 10% and ensures long-term low pressure loss, effective pollutant retention, and resistance to thermal and dynamic stresses, while maintaining the advantages of reduced pressure loss compared to closed systems.
Implementation Method 1
The passages have a narrowing cross section with a narrowing part directed towards an adjacent guide vane
Implementation Method 2
utilizing a metallic wall layer and catalytically active coatings for improved pollutant conversion
Implementation Method 3
a bypass flow filter which has a plurality of channels that are formed by at least one structured wall layer and a filter layer
Data Source
AI summary
A bypass flow filter includes a plurality of channels which are formed of at least one structured wall layer and a filter layer. Projecting guide vanes and passages, which are formed by the wall layer and lead to a different channel, are provided in at least a majority of the channels. The passages have a narrowing cross section and a narrowing part of the cross section is directed towards an adjacent guide vane. An exhaust system and a vehicle having a bypass flow filter, are also provided.