Wall-Flow Honeycomb Structure for PM Detection and Low Pressure Loss
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Solution Overview
Problem
Existing honeycomb structures in diesel particulate filters face issues with excessive pressure loss due to PM accumulation, leading to frequent filter regeneration and cleaning, increased fuel consumption, and maintenance costs, while current pressure sensors struggle to accurately detect PM levels.
Innovation Solution
A pillar-shaped honeycomb structure with specific cell density, opening diameter ratios, and partition wall properties that reduce initial pressure loss and enhance the pressure loss gradient, allowing for easier detection of PM accumulation and minimizing excessive temperature rises during regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the pressure loss remains low after a large amount of PM has accumulated in the filter, then the filter can operate longer without regeneration, but it becomes increasingly difficult to predict the amount of PM accumulation due to the pressure loss, resulting in excessive PM accumulation and possible damage to the filter
Solution Approach 1:
The patent changes the geometric parameters of the honeycomb structure by controlling the opening diameter ratio between inlet and outlet cells (0.78≤Din/Dout≤0.94) and cell density (35-47 cells/cm²). This modifies the pressure loss characteristics to create a more linear relationship between pressure loss and PM accumulation, enabling accurate detection throughout the filter's operating life.
Solution Approach 2:
The patent replaces the conventional pressure sensor-based detection system with a structurally optimized honeycomb design that inherently provides detectable pressure loss signals. The specific geometric configuration ensures that pressure loss remains proportional to PM accumulation, making the mechanical flow resistance a reliable indicator of filter status.
2Loss of energy
If the opening diameter of inlet cells is made smaller than outlet cells to reduce initial pressure loss, then pressure loss gradient increases, but the initial pressure loss becomes excessively large
Solution Approach 1:
The patent precisely controls the opening diameter ratio parameter (0.78≤Din/Dout≤0.94) to achieve an optimal balance. This specific range ensures that inlet cells have smaller openings than outlet cells, creating sufficient pressure loss gradient for detection while preventing excessively large initial pressure loss that would hinder filter operation.
Solution Approach 2:
The patent applies different opening diameter characteristics to different cell types (inlet vs. outlet cells) to optimize local flow properties. The asymmetric opening design creates targeted pressure loss characteristics in specific locations within the honeycomb structure, improving detection capability without compromising overall filter performance.
3Stress or pressure
If filter regeneration and cleaning treatment are performed frequently to remove ash accumulation, then pressure loss is reduced, but fuel consumption and maintenance costs increase
Solution Approach 1:
The patent replaces frequent mechanical cleaning operations with a structurally optimized filter that maintains stable pressure loss characteristics. The controlled opening diameter ratio and cell density configuration ensure that pressure loss remains proportional to PM accumulation, allowing for less frequent regeneration and cleaning cycles, thereby reducing fuel consumption and maintenance costs.
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 reduces the frequency of filter regeneration and cleaning, lowers maintenance costs, and enables precise PM detection, thereby preventing filter damage and optimizing fuel efficiency.
Implementation Method 1
a wall-flow type filter designed such that exhaust gas passes through porous partition walls is effective. Specifically, the wall-flow type filter has a large number of inlet cells and a large number of outlet cells adjacent to each other via porous partition walls, and can be configured with a honeycomb structure that captures PM while the exhaust gas passes through the partition walls.
Implementation Method 2
efforts have been made to reduce the pressure loss due to PM accumulation by modifying the arrangement and size of the inlet cells and the outlet cells
Implementation Method 3
an extra fuel is injected every time a certain amount of PM accumulates in the filter, thereby increasing the exhaust gas temperature and burning the soot (filter regeneration)
Data Source
AI summary
A pillar-shaped honeycomb structure includes an outer peripheral side wall, a plurality of inlet cells, and a plurality of outlet cells, wherein at least a part of the plurality of inlet cells are adjacent to at least a part of the plurality of outlet cells with each of partition walls interposed therebetween, wherein a cell density based on a total number of the plurality of inlet cells and the plurality of outlet cells is 35 to 47 cells/cm2, and wherein assuming an average value of opening diameters of the plurality of outlet cells except for those adjacent to the outer peripheral side wall is Dout, and an average value of opening diameters of the plurality of inlet cells except for those adjacent to the outer peripheral side wall is Din, 0.78≤Din/Dout≤0.94 is satisfied.