Exhaust Gas Purifying Device with Segmented Honeycomb Structure
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Solution Overview
Problem
Conventional exhaust gas purifying devices for direct injection gasoline engines face challenges in efficiently removing fine particles while minimizing pressure drop and achieving high purification efficiency for CO, HC, and NOx immediately after engine start, due to increased heat efficiency and varying particulate matter characteristics compared to diesel engines.
Innovation Solution
A plugged honeycomb structure with a honeycomb catalyst having both opened ends is used, where the honeycomb catalyst is loaded with a three-way catalyst, and the porosity and cell density of the partition walls are optimized to reduce pressure drop and enhance temperature rise, allowing for efficient purification of exhaust gases containing CO, HC, and NOx.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a plugged honeycomb structure with three-way catalyst is used to remove particulate matter, then PM removal efficiency is improved, but pressure drop increases and engine output decreases
Solution Approach 1:
The device is divided into two separate functional sections: a honeycomb catalyst section for gas purification and a plugged honeycomb structure section for PM collection. This segmentation allows each component to perform its function independently without interfering with the other, maintaining low pressure drop while achieving effective PM removal.
Solution Approach 2:
The honeycomb catalyst serves multiple functions: it purifies exhaust gases (CO, HC, NOx) and also acts as a thermal mass to rapidly heat the plugged honeycomb structure, enabling the PM collection function to activate quickly after engine start without requiring additional space or components.
2Manufacturing precision
If the amount of three-way catalyst is increased to improve purification efficiency, then CO, HC and NOx purification is improved, but pressure drop increases due to closed pores
Solution Approach 1:
The catalytic function is separated into two locations: the honeycomb catalyst (with optimized catalyst amount for gas purification) and the plugged honeycomb structure (for PM collection). This segmentation allows the honeycomb catalyst to have sufficient catalyst loading for effective gas purification without excessive pressure drop, while the plugged structure handles PM removal independently.
3Temperature
If plugged portions are formed to increase heat capacity, then catalyst activation temperature is maintained, but time required for temperature rise increases
Solution Approach 1:
The honeycomb catalyst is positioned upstream to first warm up and activate, then use its thermal mass to rapidly heat the plugged honeycomb structure. This preliminary action sequence ensures that when exhaust gases reach the plugged structure, it is already at the necessary temperature for catalyst activation, reducing overall warm-up time.
Solution Approach 2:
The honeycomb catalyst serves dual functions: purifying exhaust gases and acting as a thermal reservoir to rapidly heat the plugged honeycomb structure. This multi-functionality eliminates the need for separate heating mechanisms and reduces the time required to reach catalyst activation temperature.
4Stress or pressure
If a honeycomb catalyst with both opened ends is used, then pressure drop is reduced, but PM collection efficiency may be compromised
Solution Approach 1:
The device separates the functions of gas purification (honeycomb catalyst with opened ends for low pressure drop) and PM collection (plugged honeycomb structure). The plugged structure's alternating open/plugged cell configuration creates flow paths that effectively trap PM while maintaining reasonable pressure drop characteristics.
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
The solution effectively removes fine particles and purifies exhaust gases with a high efficiency immediately after engine start, maintaining low pressure drop and optimizing catalyst performance by using a honeycomb structure with optimized porosity and cell density.
Implementation Method 1
a honeycomb catalyst (10) including a first honeycomb base material (6) having porous partition walls (5) arranged to form a plurality of cells (4) which become through channels of a fluid, and a three-way catalyst loaded on the first honeycomb base material (6)
Implementation Method 2
a plugged honeycomb structure (20) including a second honeycomb base material (16) having porous partition walls (15) arranged to form a plurality of cells (14) which become through channels of a fluid, and plugged portions (8) arranged to plug open frontal areas of predetermined cells (14a) in a second outflow side end face (13) of the second honeycomb base material (16) and open frontal areas of remaining cells (14b) in a second inflow side end face (12)
Implementation Method 3
the porosity and cell density of the partition walls are optimized to reduce pressure drop and enhance temperature rise
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
There is disclosed an exhaust gas purifying device which has a less increase of pressure drop and can purify an exhaust gas with a high efficiency. An exhaust gas purifying device 100 comprises a honeycomb catalyst 10 including a first honeycomb base material 6 having partition walls 5 arranged to form a plurality of cells 4 and a three way catalyst; a plugged honeycomb structure 20 including a second honeycomb base material 16 having partition walls 15 arranged to form a plurality of cells 14, and plugged portions 8 arranged to plug open frontal areas of predetermined cells 14a and remaining cells 14b; and a can member 30 containing the honeycomb catalyst 10 and the plugged honeycomb structure 20. A value of a ratio of a length of the honeycomb catalyst 10 with respect to a length of the plugged honeycomb structure 20 is from 0.1 to 0.5, any catalyst is not loaded onto the plugged honeycomb structure 20, a cell density of the first honeycomb base material 6 is larger than that of the second honeycomb base material 16, an open area ratio in a first inflow side end face 2 is larger than that in a second inflow side end face 12, and a diameter of the honeycomb catalyst 10 is equal to that of the plugged honeycomb structure 20.