Plugged Honeycomb Structure with Mixed Cell Sizes
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Solution Overview
Problem
Conventional plugged honeycomb structures experience increased pressure loss when particulate matter (PM) is not deposited or in low amounts, which is a challenge for diesel engines with reduced PM emissions and stricter exhaust gas regulations.
Innovation Solution
A plugged honeycomb structure with a combination of large and small cells, where large cells are formed with inflow side plugged portions and small cells with outflow side plugged portions, specifically arranged in the outer peripheral portion to maximize open areas and minimize pressure loss while maintaining high PM collection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional plugged honeycomb structure with uniform cell size is used, then the structure is simple to manufacture, but the pressure loss increases when PM is not deposited or in low amounts
Solution Approach 1:
The honeycomb structure is segmented into two distinct cell types: large capacity cells and small capacity cells. This segmentation allows the structure to optimize flow distribution, with large cells handling bulk flow to reduce pressure loss and small cells providing sufficient filtration surface area for PM collection, thereby resolving the contradiction between manufacturing simplicity and pressure loss reduction.
Solution Approach 2:
Different regions of the honeycomb structure have different cell sizes tailored to specific functional requirements. Large capacity cells are strategically positioned to maximize open area and minimize pressure drop in high-flow regions, while small capacity cells provide adequate filtration surface area where needed, achieving local optimization of both pressure loss and filtration performance.
2Loss of energy
If large capacity cells are used to reduce pressure loss, then the open area increases and pressure loss decreases, but the PM collection capacity may be reduced
Solution Approach 1:
The structure is divided into large capacity cells for pressure loss reduction and small capacity cells for PM collection. The large cells (with greater cross-sectional areas) provide low resistance flow paths that minimize pressure drop, while the small cells (with smaller cross-sectional areas) provide sufficient surface area through their porous walls for effective PM filtration, thus resolving the contradiction between pressure loss and collection capacity.
Solution Approach 2:
The invention merges two previously separate functions into a single honeycomb structure: pressure loss reduction (achieved through large capacity cells with high open area) and PM collection (achieved through small capacity cells with sufficient filtration surface area). This combination allows the structure to simultaneously achieve low pressure loss and high PM collection capacity.
3Quantity of substance
If the number of large capacity cells is increased to maximize PM collection, then the collection capacity increases, but the pressure loss increases
Solution Approach 1:
The honeycomb structure is segmented into a balanced composition of large capacity cells and small capacity cells. The large cells are optimized for low pressure loss with high open area, while the small cells are optimized for PM collection with sufficient surface area. This segmentation creates a synergistic effect where the large cells minimize pressure drop and the small cells maximize collection capacity without either compromising the other.
Solution Approach 2:
The invention changes the parameter of cell capacity (size) to create two distinct cell types with different functional characteristics. By adjusting the capacity parameter, large cells provide low resistance flow paths that minimize pressure drop, while small cells provide adequate filtration surface area for effective PM collection, thus resolving the contradiction between collection capacity 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
The structure effectively suppresses initial pressure loss and enhances PM collection capacity, allowing for efficient filtration even with low PM deposition, suitable for engines with reduced PM emissions and stricter exhaust regulations.
Implementation Method 1
a plugged honeycomb structure having porous partition walls with which a plurality of cells are formed to become through channels of fluids (an exhaust gas and a purified gas)
Data Source
Figure 1
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AI summary
There is disclosed a plugged honeycomb structure which can collect particulate matter (PM) in large amounts and in which an increase of a pressure loss is suppressed. The plugged honeycomb structure includes a honeycomb structure section 11 having porous partition walls 5 with which a plurality of cells 4 extending from an inflow side end surface to an outflow side end surface are formed to become through channels of a fluid, the plurality of cells 4 including large cells 4a and small cells 4b having different open areas in a cross section perpendicular to an extending direction of the cells 4; inflow side plugged portions 8a arranged in inflow side end portions of the predetermined cells including the large cells 4a and the small cells 4b among the plurality of cells 4; and outflow side plugged portions 8b arranged in outflow side end portions of the remaining cells including the large cells 4a and the small cells 4b among the plurality of cells 4. The predetermined cells are outflow cells having the plugged inflow side end portions and the open outflow side end portions in the honeycomb structure section 11, and the remaining cells are inflow cells having the plugged outflow side end portions and the open inflow side end portions in the honeycomb structure section 11.