Wall-Flow Exhaust Gas Purification with Inflow Catalyst Coverage
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Solution Overview
Problem
Exhaust gas purification devices with catalysts in a wall flow structure face challenges in reducing pressure loss while maintaining effective PM trap performance and purification efficiency, particularly due to the conventional arrangement of catalysts on the inflow side of the partition wall.
Innovation Solution
The catalyst is strategically disposed on both the partition wall surface and inner regions of the inflow cells, with a coverage range of 50% to 95% at a specific reference position along the partition wall, balancing catalyst thickness to allow efficient gas flow and purification without excessive pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the catalyst is arranged on the inflow side of the partition wall to improve PM trap performance and exhaust gas purification performance, then the purification efficiency is improved, but the pressure loss increases significantly
Solution Approach 1:
The catalyst is selectively disposed only in the inflow cell side catalyst region extending from the inflow side end of the partition wall, rather than uniformly across the entire partition wall. This local placement ensures catalyst contact with exhaust gases in the critical inflow region while leaving other regions free to maintain gas flow, thus improving purification efficiency without excessive pressure loss
Solution Approach 2:
The partition wall is segmented into different functional regions: the inflow cell side catalyst region where catalyst is disposed for purification, and other regions where the partition wall structure is maintained for gas flow. This segmentation allows simultaneous optimization of both purification performance and pressure loss characteristics
2Productivity
If the catalyst coverage on the partition wall is increased to improve purification performance, then the exhaust gas contact area is increased, but the pressure loss increases
Solution Approach 1:
The catalyst coverage is precisely controlled within the range of 50% to 95% at the reference position (50% of the catalyst region length from the inflow side end). This parameter optimization ensures sufficient catalyst contact area for effective purification while preventing excessive coverage that would cause high 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 configuration effectively suppresses pressure loss and enhances PM trap performance by ensuring adequate catalyst contact with exhaust gases, improving overall purification efficiency.
Implementation Method 1
The harmful components can be removed from the exhaust gas by a filter over which a catalyst, such as a noble metal catalyst, is applied
Implementation Method 2
When the exhaust gas passes through the partition wall, the PM is accumulated in voids present in the partition wall
Implementation Method 3
the PM is accumulated in voids present in the partition wall
Data Source
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AI summary
Provided is an exhaust gas purification device that can suppress an increase in pressure loss. An exhaust gas purification device of the present disclosure includes a honeycomb substrate and an inflow cell side catalyst. The honeycomb substrate includes a porous partition wall defining a plurality of cells extending from an inflow side end surface to an outflow side end surface. The plurality of cells include an inflow cell and an outflow cell adjacent across the partition wall. The inflow cell has an open inflow side end and a sealed outflow side end. The outflow cell has a sealed inflow side end and an open outflow side end. The inflow cell side catalyst is disposed at least one of on a partition wall surface on the inflow cell side or in a partition wall inner region on the inflow cell side in an inflow cell side catalyst region of the partition wall. When a position at 50% of a length of the inflow cell side catalyst region from the inflow side end of the partition wall along the extending direction is set to a reference position, at the reference position, a proportion of a region of the partition wall covered with the inflow cell side catalyst in a plan view of the partition wall surface on the inflow cell side of the partition wall is in a range of 50% or more and 95% or less.