Honeycomb Structure with Low Young's Modulus Outer Wall
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Solution Overview
Problem
Existing honeycomb structures used as catalyst carriers and heaters in exhaust gas treatment face issues with heat shock resistance, excessive current flow due to low electrical resistance, and difficulty in integrating catalysts, leading to electrode deterioration and structural damage.
Innovation Solution
A honeycomb structure with a tubular design featuring porous partition walls and a low Young's modulus outer peripheral wall, where the electrical resistivity of the partition walls is between 1 to 200 Ωcm, and the Young's modulus ratio of the low Young's modulus portion to the partition walls is from 2 to 95%, allowing for effective heat generation and stress alleviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the honeycomb structure is heated by energization or by a metal heater, then the catalyst temperature is raised to a predetermined temperature, but cracks are easily generated in the outer peripheral wall due to heat shock
Solution Approach 1:
The patent applies local quality by creating a low Young's modulus portion specifically in the outer peripheral wall, while the partition walls maintain their original mechanical properties. This localized modification allows the outer peripheral wall to flexibly accommodate thermal expansion and contraction during heating, preventing crack generation while maintaining the overall structural integrity needed for catalyst support.
Solution Approach 2:
The patent changes the mechanical parameter (Young's modulus) of the outer peripheral wall material to be lower than that of the partition walls. This parameter change enables the outer peripheral wall to better withstand thermal stress during heating operations, resolving the contradiction between achieving high catalyst temperature and maintaining outer peripheral wall strength.
2Ease of operation
If the honeycomb structure is simply disposed under an engine and exposed to high-temperature exhaust gas, then the structure is positioned for exhaust treatment, but the outer peripheral wall is damaged by heat shock
Solution Approach 1:
The patent applies local quality by creating a low Young's modulus portion specifically in the outer peripheral wall, while the partition walls maintain their original mechanical properties. This localized modification allows the outer peripheral wall to flexibly accommodate thermal expansion and contraction during heating, preventing crack generation while maintaining the overall structural integrity needed for catalyst support.
Solution Approach 2:
The patent changes the mechanical parameter (Young's modulus) of the outer peripheral wall material to be lower than that of the partition walls. This parameter change enables the outer peripheral wall to better withstand thermal stress during heating operations, resolving the contradiction between achieving high catalyst temperature and maintaining outer peripheral wall strength.
3Temperature
If a metal heater with low electric resistance is used, then high-temperature exhaust gas can be generated, but excessive current flows through the heater when a high-voltage power source is used
Solution Approach 1:
The patent changes the electrical parameter (resistivity) of the heating portions to be within a specific range (10-1000 μΩm). This parameter change allows the heater to generate sufficient heat for high-temperature exhaust treatment while limiting excessive current flow when connected to high-voltage power sources, resolving the contradiction between temperature generation and current control.
4Strength
If the honeycomb structure is made with uniform high strength materials, then structural integrity is maintained, but heat shock resistance is reduced
Solution Approach 1:
The patent applies local quality by creating a low Young's modulus portion specifically in the outer peripheral wall, while the partition walls maintain their original mechanical properties. This localized modification allows the outer peripheral wall to flexibly accommodate thermal expansion and contraction during heating, preventing crack generation while maintaining the overall structural integrity needed for catalyst support.
Solution Approach 2:
The patent creates a composite structure where the outer peripheral wall has different mechanical properties (lower Young's modulus) compared to the partition walls. This composite approach combines the flexibility needed for heat shock resistance in the outer wall with the structural strength needed in the internal partition walls, resolving the contradiction between overall strength and heat shock resistance.
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 functions as an efficient heater with improved heat shock resistance, preventing excessive current flow and structural damage, while allowing for effective catalyst integration and prolonged durability.
Implementation Method 1
the electrical resistivity of the partition walls is from 1 to 200 Ωcm... when a voltage is applied thereto... functions as a heater
Implementation Method 2
at least a part of the outer peripheral wall is formed by a low Young's modulus portion configured to have a Young's modulus lower than that of the partition walls... stress alleviation
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A honeycomb structure 100 including a tubular honeycomb structure portion 4 having: porous partition walls 1 with which a plurality of cells 2 extending from one end surface 11 to the other end surface 12 are formed topartition through channels of a fluid; and an outer peripheral wall 3 positioned on an outermost periphery, an electrical resistivity of the partition walls 1 is from 1 to 200 Ωcm, at least a part of the outer peripheral wall 3 is formed by a low Young's modulus portion 6 configured to have a Young's modulus lower than that of the partition walls 1, and a ratio of the Young's modulus of the low Young's modulus portion 6 to the Young's modulus of the partition walls 1 is from 2 to 95%. Provided is a honeycomb structure which is a catalyst carrier and also functions as a heater when a voltage is applied thereto and which furthermore has an excellent heat shock resistance.