Honeycomb Filter Thermal Shock Resistance via Cell Sealing Ratios
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Solution Overview
Problem
Conventional honeycomb structured filters for capturing particulates in exhaust gases face issues with thermal shock during the regenerating process, leading to damage of the plugged portions and their periphery due to uneven heat distribution.
Innovation Solution
The honeycomb unit is designed with a specific weight ratio of unsealed to sealed regions and an aspect ratio that satisfies the inequality 100 / 3 ⋅ X + 5 ≤ Y ≤ 100 / 3 ⋅ X + 40, where X is the aspect ratio and Y is the weight ratio, to minimize heat deviation and prevent damage during regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the filter is used to capture particulates in exhaust gases, then the filtering function is improved, but thermal shock during regenerating process damages the plugged portions and periphery
Solution Approach 1:
The patent applies parameter changes by establishing specific mathematical relationships between geometric parameters (length ratio L/W between 0.06-0.15, width ratio W/H between 0.35-0.65) and physical parameters (porosity 30-70%, thickness ratios) of the honeycomb structure. These parameter optimizations ensure uniform heat distribution during regeneration, reducing thermal stress on plugged portions while maintaining effective particulate capture functionality.
2Productivity
If the burned-out particulates are removed by regenerating process, then the filtering capacity is restored, but the temperature rise causes thermal shock to the filter structure
Solution Approach 1:
The patent applies local quality by creating non-uniform porosity distribution within the honeycomb structure, with different porosity values in different regions (e.g., higher porosity near plugged portions, lower porosity in central regions). This localized property variation enables controlled heat distribution during regeneration, protecting thermally sensitive plugged portions while allowing effective burn-off of accumulated particulates.
Solution Approach 2:
The patent achieves equipotentiality by designing the honeycomb cell dimensions and wall thicknesses to create uniform thermal potential distribution throughout the structure during regeneration. The specific geometric ratios (L/W, W/H) and uniform material properties ensure that temperature rises evenly across all cells, eliminating thermal gradients that would cause shock and damage to the plugged portions.
3Area of stationary object
If the plugged portion is made larger to improve filtration, then the filtering area increases, but the thermal stress concentration increases
Solution Approach 1:
The patent applies segmentation by dividing the filter into multiple small honeycomb cells with uniform dimensions rather than using a single large filtering structure. This segmentation distributes thermal stress across many small plugged portions rather than concentrating it in one large area, while the cumulative filtering surface area remains sufficiently large to maintain effective particulate capture capacity.
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 design effectively reduces the occurrence of cracks and enhances the durability of the honeycomb structured body by maintaining even heat distribution and preventing thermal stress, thereby improving its structural integrity during the regenerating process.
Implementation Method 1
the thermal shock caused upon burning the PM should be suppressed; namely, the rise in temperature at the plugged portion of the cells should be suppressed
Implementation Method 2
A thermal shock which occurs due to this rise in temperature of the filter tends to damage the plugged portion and the periphery thereof
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(b)
Figure 3
AI summary
The present invention relates to a honeycomb unit which has a high thermal shock resistance at the plugged portions of the cells and the periphery thereof; is not susceptible to damage such as cracks during a regenerating process; and has a superior durability, and the honeycomb unit of the present invention is a honeycomb unit comprising a plurality of cells which are allowed to penetrate in a longitudinal direction with a wall portion therebetween, each of the cells having either one end portionbeing sealed, wherein supposing that: a ratio of a weight of an unsealed region in the cells to a weight of a sealed region in the cells is Y, and a ratio of a length in the longitudinal direction of the honeycomb unit to an area of a cross-section perpendicular to the longitudinal direction of the honeycomb unit is X, these X and Y are allowed to satisfy the following inequality (1): 100/3⋅X+5≤Y≤100/3⋅X+40 (wherein 0.1 ≤ X ≤ 0.26).