Segmented Honeycomb Structure with Angled Bonding Layers
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Solution Overview
Problem
Conventional segmented-honeycomb structures for diesel particulate filters (DPFs) are prone to cracking due to thermal stress and temperature differences, especially when loading catalysts, which affects their durability and filtration efficiency.
Innovation Solution
A honeycomb structure design featuring prismatic columnar segments bonded with specific circumferential and central bonding layers, where the circumferential bonding layers are angled between 25 to 45 degrees to prevent crack formation, and the central segments are arranged in a quadrangle shape to enhance structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a segmented honeycomb structure is used to prevent breakage under thermal stress, then the overall structural strength is improved, but cracks easily occur in the bonding layers of the circumferential portion
Solution Approach 1:
The honeycomb structure is divided into multiple segments that are bonded together with bonding layers. This segmentation allows the structure to flex and distribute thermal stress more evenly, preventing catastrophic failure while maintaining overall strength. The segments can move independently to accommodate thermal expansion and contraction.
Solution Approach 2:
The bonding layers are strategically positioned and configured with specific geometric angles (25-45 degrees) at critical circumferential locations where thermal stress concentrates. This local optimization of bonding layer orientation provides enhanced crack resistance precisely where needed, rather than uniformly throughout the entire structure.
2Power
If high-temperature heat treatment is applied to bake the oxidation catalyst, then the catalytic activity is improved, but cracks occur in the bonding layers during heat treatment
Solution Approach 1:
The bonding layers are pre-configured with optimal geometric angles (25-45 degrees) before the catalyst loading and heat treatment processes. This preliminary structural preparation ensures that when high-temperature heat treatment is later applied to activate the catalyst, the bonding layers are already positioned to withstand the thermal stress without cracking.
3Volume of moving object
If large-sized SiC is used to downsize the DPF, then the DPF size is reduced, but temperature difference between inside and outside increases causing cracks
Solution Approach 1:
The DPF is constructed from multiple segments that can independently respond to thermal gradients. This segmentation reduces the effective thermal mass and allows heat to distribute more uniformly across the structure, minimizing temperature differences between the inside and outside even in compact large-sized SiC configurations.
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 configuration effectively suppresses crack occurrence in the bonding layers, enhancing the durability and filtration efficiency of the DPF by preventing crack extension and maintaining structural integrity under thermal stress and temperature variations.
Implementation Method 1
The segmented-structure honeycomb structure has a problem that the total thermal stress of the honeycomb structure can be absorbed but cracks etc. are easy to occur in the bonding layers of the circumferential portion
Implementation Method 2
the honeycomb structure is coated with slurry including the oxidation catalyst and then is subject to heat treatment at high temperature to be baked
Implementation Method 3
measures to prevent the breakage of the DPF are necessary. Particularly, a passenger car and the like have a tendency to increase the frequency of reproduction process
Implementation Method 4
a purification device that purifies exhaust gas emitted from an automobile that uses a diesel engine as a power source employs a diesel particulate filter (DPF)
Data Source
AI summary
A honeycomb structure includes plugged honeycomb segments, circumferential bonding layers, central bonding layers and a circumferential wall. An angle θ between a first direction of extension of at least one of the circumferential bonding layers and a second direction of extension of a line segment that connects a centroid of the honeycomb structure and an intersection point at which the circumferential bonding layer in the first direction intersects with the circumferential wall is 25 to 45°, and the outermost segment bonded by the circumferential bonding layer in the first direction exists on a parallel line to a direction of extension of the central bonding layer passing through the centroid.