Honeycomb Structure Porosity Gradient Bonding
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Solution Overview
Problem
Existing honeycomb structures for diesel particulate filters face challenges in achieving sufficient thermal shock resistance during filter regeneration, leading to potential cracks and defects due to inadequate bonding strength and stress relaxation in the bonding material layers.
Innovation Solution
A honeycomb structure with specific porosity gradients in the bonding material layers and controlled compression Young's modulus, combined with inorganic fibers and organic binders, to enhance bonding strength and stress relaxation, ensuring the structure can withstand thermal stress without cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bonding material layers are added to integrate honeycomb segments, then thermal shock resistance is improved, but bonding strength between segments and bonding material layers is insufficient
Solution Approach 1:
The bonding material layer is designed with non-uniform porosity distribution, where the outer portion has lower porosity (higher density) and the central portion has higher porosity. This local quality variation allows the outer portion to provide strong bonding with the honeycomb segment surface while the central portion provides stress relaxation, simultaneously achieving both bonding strength and thermal shock resistance.
Solution Approach 2:
The bonding material layer is formulated as a composite material containing inorganic fibers, inorganic binders, and organic binders. This composite structure combines the high-temperature stability of inorganic components with the bonding and flexibility properties of organic components, enabling both strong adhesion and stress relaxation capabilities.
2Reliability
If bonding material layers are added to integrate honeycomb segments, then thermal shock resistance is improved, but stress relaxation effect of bonding material layers is insufficient
Solution Approach 1:
The bonding material layer is designed with non-uniform porosity distribution, where the outer portion has lower porosity (higher density) and the central portion has higher porosity. This local quality variation allows the outer portion to provide strong bonding with the honeycomb segment surface while the central portion provides stress relaxation, simultaneously achieving both bonding strength and thermal shock resistance.
Solution Approach 2:
The bonding material layer incorporates a porous structure with controlled porosity gradient. The porous central portion can absorb and dissipate thermal stresses through its void space, providing effective stress relaxation while the less porous outer portion maintains structural integrity and bonding strength.
3Quantity of substance
If filter size is enlarged to increase capacity, then particulate matter collection is improved, but thermal stress during regeneration increases leading to defects
Solution Approach 1:
The filter is divided into multiple honeycomb segments that are integrated using bonding material layers. This segmentation allows the large filter to be constructed from smaller, more manageable units that can better accommodate thermal expansion and stress, reducing the risk of defects during regeneration while maintaining the required collection capacity.
Solution Approach 2:
The bonding material layer is formulated as a composite material containing inorganic fibers, inorganic binders, and organic binders. This composite structure combines the high-temperature stability of inorganic components with the bonding and flexibility properties of organic components, enabling both strong adhesion and stress relaxation capabilities.
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 proposed honeycomb structure effectively inhibits cracks and maintains thermal shock resistance during filter regeneration, providing a durable solution for diesel particulate filters by optimizing bonding material properties.
Implementation Method 1
the bonding material layers have a compression Young's modulus along the Z-axis of 5 to 100 MPa... possess an excellent stress relaxation effect
Implementation Method 2
by suppressing migration in the course of drying and curing
Data Source
AI summary
A honeycomb structure 1 comprising a honeycomb segment bonded body 10 having a number of honeycomb segments 2 integrated on each bonding planes via bonding material layers 9 has a structure so that a number of cells 5 providing fluid flow channels are disposed in parallel in the direction of center axis thereof. The honeycomb structure 1 is constructed so that the porosity of an outer portion of the bonding material layers 9 (an area from the interface with the honeycomb segment-bonding plane to a point apart from that interface by a distance equivalent to 20% of the entire layer thickness) is smaller than the porosity of a central portion located inward of the outer portion, and so that the bonding material layers 9 have a compression Young's modulus along the Z-axis of 5 to 100 MPa.