Exhaust Gas Purification Filter With Gradient Pores
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Solution Overview
Problem
Current exhaust gas purification filters struggle to effectively collect particulate matter (PM) with smaller diameters due to a mismatch between PM particle size and pore diameter, leading to reduced PM collection performance and increased pressure loss.
Innovation Solution
The exhaust gas purification filter features a porous partition wall with communicating pores that have a specific diameter gradient, where the inlet neck diameter is smaller than the surface opening diameter, and a surface opening ratio of 40% or more, enhancing the likelihood of PM collision and collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pore diameter in the partition wall is reduced to collect smaller PM particles, then PM collection performance is improved, but pressure loss increases
Solution Approach 1:
The partition wall is designed with non-uniform pore distribution: the surface layer has a first pore diameter (15-25 μm) for low resistance, while the inner layer has a second pore diameter (5-15 μm) for PM collection. This local differentiation allows each layer to perform its specific function optimally without compromising overall performance
Solution Approach 2:
The partition wall is segmented into two distinct layers: a surface layer and an inner layer, each with different pore characteristics. This segmentation enables the surface layer to handle gas flow with low pressure loss while the inner layer captures PM particles effectively
2Loss of energy
If the pore diameter in the partition wall is increased to reduce pressure loss, then gas permeation is improved, but PM collection performance deteriorates
Solution Approach 1:
Different regions of the partition wall have different pore diameters optimized for their specific functions: the surface layer uses larger pores (15-25 μm) to minimize pressure loss, while the inner layer uses smaller pores (5-15 μm) to capture PM particles
Solution Approach 2:
The partition wall is divided into functional segments: the surface layer segment handles gas permeation with low resistance, while the inner layer segment performs PM collection, allowing both requirements to be satisfied simultaneously
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 improves PM collection performance by increasing the probability of PM collision and reducing pressure loss, while maintaining efficient gas permeation.
Implementation Method 1
communicating pores which, as viewed in cross section in a thickness direction of the partition wall, have a surface opening on the gas-inflow-side surface and a plurality of portions each having a diameter which is reduced and then increased again from the surface opening
Implementation Method 2
the inlet neck diameter of each of the communicating pores is smaller than the surface opening diameter of the communicating pores; and an average value of the inlet neck diameters of the communicating pores is 5 μm or more and 15 μm or less
Data Source
Figure 1~2
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AI summary
In an exhaust gas purification filter (1), the partition wall (12) has communicating pores (120). Each of the communicating pores (120) has a surface opening (121) on the gas-inflow-side surface and a plurality of portions (122), each of the portions of each of the communicating pores having a diameter, the diameter of each of the portions of each of the communicating pores being reduced and then increased again from the surface opening (121) of the corresponding one of the communicating pores, one of the portions of each of the communication pores, whose diameter is the smallest, being defined as an inlet neck portion (122N) of the corresponding one of the communication pores. As viewed in cross section in a thickness direction of the partition wall (12), the surface opening (121) of each of the communication pores (120) has a diameter defined as a surface opening diameter (A), the inlet neck portion (122N) of each of the communication pores has a diameter defined as an inlet neck diameter (B). The inlet neck diameter (B) of each of the communication pores is smaller than the surface opening diameter (A) thereof, and an average value of the inlet neck diameters (B) of the communication pores is 15 µm or less. A surface opening ratio of the communicating pores (120) in plan view of the gas-inflow-side partition wall surface is 40% or more.