Honeycomb Segments Bonding Layer Thermal Stress
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Solution Overview
Problem
Honeycomb structures used as diesel particulate filters face defects such as cracks due to thermal stress, which are exacerbated by uneven temperature rises and thermal expansion, leading to increased pressure loss and reduced effectiveness over time.
Innovation Solution
A honeycomb structure with integrally joined segments using a bonding material layer, where the thickness of the bonding material layer is optimized to reduce thermal stress, with a specific ratio between end and central thicknesses to manage temperature distribution and prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a honeycomb structure uses silicon carbide as raw material to achieve excellent heat resistance, then heat resistance is improved, but thermal expansion coefficient increases and thermal shock resistance decreases leading to crack formation
Solution Approach 1:
The honeycomb structure is divided into multiple honeycomb segments that are integrally joined together. This segmentation allows each segment to expand and contract independently under thermal stress, reducing the overall thermal shock resistance problem while maintaining excellent heat resistance of silicon carbide material
Solution Approach 2:
The invention uses composite construction by joining multiple honeycomb segments together to form a integrated structure. This composite approach combines the high heat resistance of silicon carbide with reduced thermal stress through the segmented architecture, preventing crack formation
2Reliability
If the bonding material layer thickness is increased to reduce thermal stress influence, then thermal stress resistance is improved, but pressure loss increases due to thicker bonding layers
Solution Approach 1:
The bonding material layer thickness is optimized to achieve local quality balance - thick enough to provide thermal stress resistance and structural integrity, but thin enough to minimize pressure loss. This local optimization resolves the contradiction between thermal stress resistance and pressure loss
3Productivity
If the honeycomb structure is enlarged to increase filtration capacity, then productivity is improved, but thermal stress increases remarkably leading to more frequent cracks
Solution Approach 1:
The enlarged honeycomb structure is divided into multiple segments that are integrally joined. This segmentation allows the large-scale structure to accommodate thermal expansion and contraction, preventing crack formation even as filtration capacity increases through enlargement
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 optimized bonding material layer effectively inhibits the formation of cracks, allowing for higher particulate matter accumulation without significant pressure loss, thereby enhancing the durability and performance of diesel particulate filters.
Implementation Method 1
a honeycomb structure having a plurality of honeycomb segments integrally joined at joint faces by means of a bonding material layer... capable of effectively inhibiting a defect such as a crack due to thermal stress from being caused by lightening the influence of thermal stress generated upon use or upon regeneration
Implementation Method 2
the bonding material layer has a thermal conductivity of 0.1 W/mK - 10 W/mK... thickness of the bonding material layer satisfies the relation of (T2) = (1.2 to 10.0) × (T1) between an average thickness (T1) at positions located at both the end portions... and a maximum thickness (T2)
Data Source
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AI summary
A honeycomb structure useful as exhaust gas trapping filter, particularly, as a diesel particulate filter (DPF) for trapping particulate matter, etc. in diesel engine exhaust gas and capable of effectively inhibiting defects such as cracks due to thermal stress, by reducing influence of thermal stress generated upon use or regeneration. The honeycomb structure includes: an integrally joined body constituted of plural honeycomb segments at joint faces with a bonding material layer, and an outer peripheral coat layer. Thickness of the bonding material layer satisfies the relation: (T2) = (1.2 to 10.0) X (T1) between an average thickness (T1) at positions (X1) and (X2) located at the both ends in the central axis direction of segments and a maximum thickness (T2) between positions (Y1) and (Y2) apart from respective ends in 3 to 40% of the whole length of the honeycomb segment.