Honeycomb Filter Plugging Pore Distribution for Thermal Shock Resistance
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Solution Overview
Problem
Honeycomb structures used in filters for removing particulate matter from exhaust gases face issues with increased pressure loss and reduced strength due to deposits, especially when plugging portions have high porosity, leading to potential cracks and bonding strength deficiencies.
Innovation Solution
A honeycomb structure with plugging portions having a porosity of 50 to 90% and a thickness of 3 to 30 mm, featuring pores with a sectional area of 0.15 mm² or more occupying 30% or more of the total pore area, centered around the central axis, which enhances thermal shock resistance and bonding strength while maintaining low pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the porosity of plugging material is increased to reduce pressure loss and improve thermal shock resistance, then the resistance to thermal shock is improved, but the bonding strength of the plugging portion becomes insufficient
Solution Approach 1:
The patent applies local quality by creating a gradient in pore characteristics within the plugging portion. Specifically, it ensures that pores with a sectional area of 0.15 mm² or more (which provide thermal shock resistance) occupy 30% or more of the total pore area, while controlling the overall porosity to be 50-90%. This selective control of pore size distribution allows the plugging portion to simultaneously achieve excellent thermal shock resistance through large pores and sufficient bonding strength through controlled overall porosity and pore distribution.
2Reliability
If deposits accumulate in the opening end portion of the cell, then the filtering capability is improved, but the pressure loss increases and output decreases
Solution Approach 1:
The patent applies preliminary action by pre-designing the plugging portion with specific pore characteristics (porosity of 50-90% and large pores occupying 30% or more of total pore area) before deposits accumulate. This pre-configuration ensures that even when deposits accumulate during operation, the structured pore distribution maintains adequate flow paths, preventing excessive pressure loss while still allowing deposits to form for filtering purposes.
3Strength
If the thickness of plugging portion is increased to improve bonding strength, then the bonding strength is improved, but the pressure loss increases
Solution Approach 1:
The patent applies parameter changes by optimizing the thickness of the plugging portion to be within 3-30 mm and controlling the porosity to be 50-90%, with large pores (0.15 mm² or more sectional area) occupying 30% or more of the total pore area. This parameter optimization achieves sufficient bonding strength without excessive thickness, thereby maintaining low pressure loss while ensuring adequate structural integrity.
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 prevents crack generation and maintains sufficient bonding strength even with high porosity plugging portions, reducing pressure loss and optimizing exhaust gas capturing efficiency.
Implementation Method 1
a resistance to thermal shock is achieved (to prevent crack generation or dissolved loss due to the thermal shock during regeneration of the filter)
Implementation Method 2
the partition wall 2 functions as a filter to capture the PM and the like
Data Source
Figure 1(a)~1(c)
Figure 2
AI summary
There is provided a honeycomb structure which is excellent in such a resistance to thermal shock as to prevent generation of cracks or dissolved losses in partition wall intersections as critical damages for a filter and which is capable of securing a sufficient bonding strength to partition walls even in a case where plugging portions have a high porosity. A honeycomb structure includes: porous partition walls arranged to define cells connecting two end faces to each other; and plugging portions arranged to plug the cells in either end face. A porosity of each plugging portion is 50 to 90%, and an area of pores each having a sectional area of 0.15 mm2 or more is 30% or more of a total pore area, the sectional area occupying an arbitrary section including a central axis of the plugging portion.