Exhaust Purifying Filter with Localized Catalyst Distribution
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Solution Overview
Problem
Conventional exhaust purifying filters with integrated three-way catalysts face a trade-off between pressure loss, catalyst purification performance, and particulate matter capturing performance, leading to increased pressure loss and reduced output, especially with the deposition of particulate matters like ashes over time.
Innovation Solution
The exhaust purifying filter design features a filter substrate with a porous partition wall where the three-way catalyst is carried on the surface, with a specific pore distribution and catalyst content rate that minimizes initial pressure loss and allows for high catalyst purification and particulate matter capturing performance without limiting the catalyst amount, by ensuring the catalyst particles are smaller than the pore diameter and are more concentrated on the inflow-side cell side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the three-way catalyst is carried on the GPF with conventional pore distribution and catalyst occupancy, then the catalyst purification performance can be improved, but the pressure loss is increased and the output is lowered
Solution Approach 1:
The patent applies local quality by creating different catalyst occupancy rates in different regions of the filter substrate. The inlet-side region has a first catalyst occupancy rate while the outlet-side region has a second catalyst occupancy rate that is different from the first. This spatial variation in catalyst distribution allows optimization of purification performance in different zones while managing pressure loss characteristics, resolving the contradiction between purification effectiveness and flow resistance.
2Reliability
If the catalyst amount is increased to improve purification performance, then the catalyst purification performance is improved, but the pressure loss is increased due to catalyst particle blockage
Solution Approach 1:
The patent implements local quality through non-uniform catalyst distribution where the inlet-side region and outlet-side region have different catalyst occupancy rates. This allows higher catalyst loading in regions where purification is most needed while maintaining lower catalyst occupancy in regions where flow resistance would be problematic, thereby improving overall purification performance without excessively increasing pressure loss and maintaining output.
3Reliability
If the pore size is reduced to improve particulate matter capturing performance, then the particulate matter capturing performance is improved, but the pressure loss is increased
Solution Approach 1:
The patent applies local quality by varying the catalyst occupancy rate between the inlet-side region and outlet-side region of the filter substrate. This regional differentiation allows optimization of the balance between particulate matter capture and pressure loss characteristics in different zones of the filter, resolving the contradiction between capturing performance and energy loss.
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 design effectively reduces pressure loss while maintaining high catalyst purification and particulate matter capturing performance, even after deposition of particulate matters, by ensuring the catalyst particles are smaller than the pore diameter and are more concentrated on the inflow-side cell side, enhancing contact opportunities and reducing blockage.
Implementation Method 1
a three-way catalyst (for example, a TWC 33 which will be described later) which is carried on the partition wall
Implementation Method 2
a filter substrate (for example, a filter substrate 320 which will be described later) in which a plurality of cells extending from an inflow-side end surface
Data Source
AI summary
Provided is an exhaust purifying filter having high catalyst purification performance and particulate matter capturing performance while reducing pressure loss. A GPF includes a filter substrate in which a plurality of cells extending from an inflow-side end surface to an outflow-side end surface are partitioned and formed by a porous partition wall and an inflow-side cell in which an opening in the outflow-side end surface is sealed and an outflow-side cell in which an opening in the inflow-side end surface is sealed are alternately disposed; and a TWC which is carried on the partition wall, wherein a difference between a total volume of pores having pore diameters within a range of 0.1 μm to 10.7 μm in pore distribution of the GPF and a total volume of pores having pore diameters within a range of 0.1 μm to 10.7 μm in pore distribution of the filter substrate is 0.015 ml/g˜0.06 ml/g.