Honeycomb Catalyst and Filter Integration for Exhaust Pressure Drop
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Solution Overview
Problem
Conventional exhaust gas purifying devices for direct injection gasoline engines face issues with increased pressure drop when using wall flow type filters, leading to reduced engine output and inadequate catalyst activation temperatures, especially during engine startup.
Innovation Solution
A honeycomb catalyst with a loaded three-way catalyst is positioned upstream of a honeycomb filter in a cylindrical can member, where the catalyst is on the inflow side and the filter is on the outflow side, with a longer catalyst length compared to the filter to minimize pressure drop and ensure efficient particulate matter collection and purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a wall flow type filter is mounted in addition to a conventional exhaust gas purifying device, then particulate matter can be removed, but pressure drop increases causing engine output to decrease
Solution Approach 1:
The patent combines a flow-through type honeycomb catalyst and a wall flow type honeycomb filter into a single integrated exhaust gas purifying device. The catalyst and filter are positioned in series within the same housing, allowing both functions to work together without requiring separate components. This merging reduces the overall pressure drop compared to having separate filter and catalyst devices, while maintaining effective particulate matter removal and exhaust gas purification.
Solution Approach 2:
The exhaust gas purifying device performs multiple functions simultaneously: the honeycomb catalyst purifies exhaust gas by catalytic conversion, while the honeycomb filter collects particulate matter through wall flow filtration. Both functions are integrated into one device that handles the entire exhaust gas flow path, making the system multi-functional and eliminating the need for separate purification and filtration devices.
2Object-affected harmful factors
If a wall flow type filter is used, then particulate matter collection is improved, but catalyst activation temperature is not reached immediately after engine startup
Solution Approach 1:
The device is segmented into two distinct functional sections: a flow-through type honeycomb catalyst section and a wall flow type honeycomb filter section. The catalyst section is positioned upstream to handle exhaust gas purification, while the filter section is positioned downstream for particulate matter collection. This segmentation allows the catalyst to receive hot exhaust gas first for immediate activation, while the filter processes the gas afterward, solving the temperature activation problem.
Solution Approach 2:
The flow-through type honeycomb catalyst is positioned upstream of the wall flow type honeycomb filter in the exhaust gas flow path. This preliminary positioning ensures that the catalyst receives hot exhaust gas first and can activate its catalytic function before the gas reaches the filter. The catalyst's exothermic reactions further heat the exhaust gas, ensuring optimal conditions for subsequent filter operation and maintaining catalyst activation temperature immediately after engine startup.
3Object-affected harmful factors
If three way catalyst is loaded onto partition walls of wall flow type filter, then purification function is added, but pores are closed causing excessive pressure drop
Solution Approach 1:
The device separates the catalyst loading function from the filter structure. Instead of loading three way catalyst onto the partition walls of the wall flow filter (which would close pores), the catalyst is placed in a separate flow-through type honeycomb structure. This segmentation maintains the porosity and flow characteristics of the filter while providing dedicated catalyst volume for effective exhaust gas purification without excessive pressure drop.
Solution Approach 2:
Different regions of the exhaust gas purifying device have different structural qualities optimized for their specific functions. The honeycomb catalyst region has a flow-through structure with adequate wall thickness for catalyst loading, while the honeycomb filter region has thin-walled porous partition walls optimized for particulate matter collection. This local quality differentiation allows each section to perform its function efficiently without compromising the other.
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 reduces pressure drop and enables high-efficiency exhaust gas purification and particulate matter collection immediately after engine startup, maintaining performance without excessive pressure drop or catalyst activation delays.
Implementation Method 1
a three way catalyst loaded onto the partition walls of the first honeycomb structure
Implementation Method 2
when the exhaust gas passes through the partition walls, the particulate matter contained in the exhaust gas is collected by the partition walls
Data Source
Figure 1~2
Figure 3~4
AI summary
There is disclosed an exhaust gas purifying device which has a less increase of pressure drop and can purify an exhaust gas and collect a particulate matter with a high efficiency even immediately after start of an engine. An exhaust gas purifying device 1 comprises a honeycomb catalyst 10 including a first honeycomb structure and a three way catalyst, a honeycomb filter 20 and a cylindrical can member 30, and the honeycomb catalyst 10 and the honeycomb filter 20 are disposed in the can member 30 so that an inflow side end face 15 of the honeycomb catalyst 10 faces an inflow port 31 of the can member 30, an outflow side end face 26 of the honeycomb filter 20 faces an outflow port 32 of the can member 30. Moreover, a length of the honeycomb catalyst 10 is from 2.0 to 10.0 times a length of the honeycomb filter 20, the length of the honeycomb filter 20 is from 0.1 to 0.5 time an outer diameter of the honeycomb filter 20, and a cell density of the honeycomb catalyst 10 is larger than that of the honeycomb filter 20.