Particulate Filter Catalyst Layer Gradient for Pressure Loss
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Solution Overview
Problem
The wall-flow type particulate filter faces a trade-off between pressure loss suppression and toxic gas purifying performance, where increasing the catalyst layer's formation region improves purifying performance but increases pressure loss, and conventional designs with catalyst layers over 80% of the base material length fail to adequately suppress pressure loss.
Innovation Solution
A particulate filter design with a wall-flow type base material and a catalyst layer where the first catalyst layer is formed over 80% of the base material length, with a thickness that decreases from 20% to 80% of the length, and a second catalyst layer on the pore surface, along with a catalyst non-formation region, to reduce pressure loss while maintaining high purifying performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the catalyst layer formation region is increased to improve toxic gas purifying performance, then the purifying performance is improved, but the pressure loss increases
Solution Approach 1:
The catalyst layer thickness is varied locally along the base material length. The thickness increases from the exhaust gas entry side toward the exit side, with the thicker region positioned in the downstream area where exhaust gas flow rate and PM concentration are lower. This local variation optimizes catalytic activity where needed while minimizing pressure loss in upstream regions with higher flow resistance.
Solution Approach 2:
The invention transitions from a uniform catalyst layer design to a gradient thickness design, adding a dimensional variation along the length of the base material. This dimensional change allows the catalyst layer to have different thicknesses at different positions, enabling simultaneous optimization of purifying performance and pressure loss suppression through spatially differentiated catalytic activity.
2Reliability
If the catalyst layer thickness is increased to enhance catalytic activity, then the toxic gas conversion efficiency is improved, but the pressure loss due to PM capture increases
Solution Approach 1:
The catalyst layer thickness is varied locally along the base material length. The thickness increases from the exhaust gas entry side toward the exit side, with the thicker region positioned in the downstream area where exhaust gas flow rate and PM concentration are lower. This local variation optimizes catalytic activity where needed while minimizing pressure loss in upstream regions with higher flow resistance.
Solution Approach 2:
The invention changes the physical parameter of catalyst layer thickness from a constant value to a gradient distribution. By controlling the thickness parameter to increase progressively from entry to exit side, the system achieves higher catalytic activity in downstream regions while maintaining lower thickness in upstream regions to reduce flow resistance and pressure 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 toxic gas purifying performance by minimizing deep layer deposition of particulate matter and ensuring sufficient contact between the catalyst layer and exhaust gas, achieving a balance between pressure loss suppression and purifying efficiency.
Implementation Method 1
The PM is captured in the porous partition wall
Implementation Method 2
the toxic gas substance is purified by the catalyst layer formed on the partition wall
Data Source
AI summary
According to the present invention, a wall-flow type particulate filter in which pressure loss is suppressed despite a large formation region of a catalyst layer is provided. The particulate filter disclosed herein includes a wall-flow type base material and a catalyst layer formed on the base material. The base material includes an inlet side cell whose only end part on an exhaust gas entry side is open, an outlet side cell whose only end part on an exhaust gas exit side is open, and a partition wall that sections between the inlet side cell and the outlet side cell and includes a plurality of pores communicating between the inlet side cell and the outlet side cell. A first catalyst layer is formed on a surface of the partition wall that is in contact with the inlet side cell. The first catalyst layer is provided in a region over 80% of a total length of the base material from an end part of the base material on the exhaust gas entry side toward an end part thereof on the exhaust gas exit side. In at least a region from a position corresponding to 20% of the total length of the base material to a position corresponding to 80% thereof, from the end part of the base material on the exhaust gas entry side, the first catalyst layer is inclined so that a thickness of the first catalyst layer decreases from the end part on the exhaust gas entry side toward the end part on the exhaust gas exit side.