Multi-Layer Metal Foam Particle Filter for Exhaust Gas
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Solution Overview
Problem
Existing diesel particulate filters face challenges due to the high density and brittleness of ceramic materials, increased fuel consumption, and high manufacturing costs of fiber structures, as well as insufficient strength and thermal expansion issues, which hinder effective and cost-effective particle separation in exhaust gases from internal combustion engines.
Innovation Solution
A filter medium composed of multiple layers of open-pore metal foam, made from nickel or iron alloys, with varying thickness, porosity, and pore size, is used to separate particles, where the first layer has a larger mean pore size and porosity, and subsequent layers have progressively smaller sizes, enhancing separation efficiency while minimizing material usage and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ceramic materials are used for the filter medium, then temperature resistance is improved, but mass increases and fuel consumption increases
Solution Approach 1:
The patent changes the material parameter from ceramic to metal foam (nickel or iron alloys), which fundamentally alters the density and strength characteristics. This parameter change reduces mass while maintaining temperature resistance through the inherent thermal stability of metal alloys, thereby resolving the contradiction between temperature resistance and mass.
Solution Approach 2:
The patent employs metal foam as a composite material structure that combines the strength and temperature resistance of metals with a porous architecture. This composite approach allows the filter medium to achieve both thermal stability and reduced mass compared to solid ceramic materials, addressing the contradiction effectively.
2Temperature
If ceramic materials are used for the filter medium, then temperature resistance is improved, but the materials become brittle and prone to destruction
Solution Approach 1:
The patent transitions from ceramic materials to metal foam materials, changing the fundamental material parameter from brittle ceramic to ductile metal. This parameter change eliminates the brittleness issue while maintaining temperature resistance, as metal alloys exhibit ductile behavior and can withstand thermal cycling without fracturing.
Solution Approach 2:
The patent adopts metal foam as a replaceable filter medium that can be easily replaced when worn. This approach accepts that the filter medium has a limited service life but ensures reliability during operation through the ductility and damage tolerance of metal materials, avoiding the catastrophic failure mode of brittle ceramics.
3Manufacturing precision
If fiber structures are used for the filter medium, then separation capability is improved, but manufacturing costs increase
Solution Approach 1:
The patent changes the material parameter from expensive fiber materials to metal foam (nickel or iron alloys). This parameter change maintains the porous structure necessary for particle separation while significantly reducing manufacturing costs, as metal foam can be produced through cost-effective processes like powder metallurgy and extrusion.
Solution Approach 2:
The patent utilizes metal foam as a porous material that provides effective particle separation through its open-cell structure. The porous architecture delivers separation capability comparable to fiber structures while the metal foam material itself is more cost-effective to manufacture, resolving the contradiction between separation capability and manufacturing cost.
4Manufacturing precision
If fiber structures are used for the filter medium, then separation capability is improved, but strength is insufficient
Solution Approach 1:
The patent changes the material parameter from fiber to metal foam, transitioning from a material with adequate separation capability but insufficient strength to a material that provides both strong structural integrity and effective particle separation. The metal foam's inherent strength properties resolve the contradiction while maintaining separation functionality.
5Temperature
If ceramic materials are used for the filter medium, then temperature resistance is improved, but thermal expansion compensation becomes more complex
Solution Approach 1:
The patent changes the material parameter from ceramic to metal foam, selecting materials with thermal expansion characteristics that are more compatible with the housing material. This parameter change reduces the thermal expansion mismatch and simplifies the design requirements for thermal expansion compensation, eliminating the need for complex compensation mechanisms.
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 multi-layer metal foam filter medium effectively separates particles from exhaust gases, reducing fuel consumption and manufacturing costs while providing improved strength and thermal compatibility, ensuring efficient particle removal and compliance with statutory provisions.
Implementation Method 1
exhaust gas of an internal combustion engine containing particles is guided through a filter medium. The filter medium is made of an open-pore metal foam and is made, in this connection of at least two layers of such a foam.
Data Source
AI summary
The invention relates to an apparatus for the separation of particles contained in exhaust gases of internal combustion engines in which the exhaust gas flow is guided through a filter medium in which particles can be absorbed and held back. The invention should improve the separation in a cost effective manner with respect to conventional particle filters. In accordance with the invention, the filter medium (1) is made from a metal open-pore foam having at least two layers (1.1, 1.2, 1.3) which each have a thickness, porosity and/or pore size in the flowthrough direction through the filter medium which differ from one another. In one embodiment, the particle filter includes first and second filter medium layers where the first filter medium has a mean pore size larger than a mean pore size of the second filter medium, and the first filter medium has a thickness that increases in a direction of the exhaust gas flow inlet passage of the filter housing.