Honeycomb Unit Brazing Length Variation for Thermal Stress
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Solution Overview
Problem
Honeycomb units for exhaust emission control face challenges in accommodating temperature changes, leading to potential deformation and reduced durability due to inadequate brazing material arrangement, which affects the rigidity and strength of the structure.
Innovation Solution
The honeycomb unit design features a brazing arrangement where the second joining portion, overlapping the joining strip, has a larger brazing length than the first joining portion, enhancing the structure's rigidity and allowing for temperature changes while minimizing the use of brazing material. The joining strip is positioned only on the exhaust outlet side to allow expansion and reduce load on the honeycomb structure, with the rear end located closer to the exhaust outlet to maintain joining strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the brazing material arrangement does not account for temperature change, then the structure is simple to manufacture, but the honeycomb structure deforms due to thermal expansion
Solution Approach 1:
The patent applies local quality by differentiating brazing lengths at different locations. The second joining portion (at the exhaust outlet side) has a longer brazing length than the first joining portion (at the exhaust inlet side), locally enhancing rigidity where thermal expansion stress is highest to prevent deformation while avoiding unnecessary brazing material elsewhere
Solution Approach 2:
The patent changes the parameter of brazing length based on thermal expansion requirements. By making the brazing length variable rather than uniform, the structure accommodates temperature changes more effectively, with longer brazing at the exhaust outlet side providing greater flexibility to handle thermal stress
2Strength
If the joining strip is positioned to maximize joining strength, then the connection is strong, but the honeycomb structure cannot expand freely causing deformation
Solution Approach 1:
The joining strip is positioned locally at the exhaust outlet side rather than uniformly distributed. This localized positioning provides sufficient joining strength where needed while allowing the honeycomb structure to expand freely at the exhaust inlet side, preventing deformation during thermal cycles
Solution Approach 2:
The brazing arrangement is segmented into two distinct portions with different characteristics. The first joining portion has shorter brazing length for flexibility, while the second joining portion has longer brazing length for strength, allowing different functional requirements to be met at different locations
3Quantity of substance
If uniform brazing length is used at all joining portions, then the structure is simple to manufacture, but excessive brazing material is used without necessary strength
Solution Approach 1:
The patent implements local quality by varying brazing length according to functional requirements. Longer brazing length is applied at the second joining portion (exhaust outlet side) where higher strength is needed, while shorter brazing length is used at the first joining portion (exhaust inlet side) where less strength is required, optimizing material usage
Solution Approach 2:
The patent applies partial action by providing brazing material only where and to the extent necessary. Rather than uniform full-length brazing, the design uses shorter brazing at the first joining portion and longer brazing only at the second joining portion, avoiding excessive material usage while maintaining sufficient strength
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 design improves the rigidity and durability of the honeycomb structure by accommodating temperature changes and reducing deformation, while optimizing brazing material usage and maintaining joining strength, as demonstrated by experimental data showing enhanced strength and reduced cell deformation.
Implementation Method 1
the honeycomb structure has a temperature which increases by heat of exhaust gas passing therethrough. This increase in temperature of the honeycomb structure is followed by increase in temperature of the metal outer tube
Implementation Method 2
The metal outer tube is brazed to the honeycomb structure through brazing materials at locations between the metal outer tube and the honeycomb structure
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A metal honeycomb structure (11) includes planar and corrugated sheets (15, 16) brazed together at first and second joining portions (17A, 17B) made of brazing materials applied to the corrugated sheet (16). The first and second joining portions (17A, 17B) are located proximate exhaust inlet and outlet (21, 22) of the honeycomb structure (11). The honeycomb further includes a joining strip (18) joined to a metal outer tube (12). The joining strip (18) is made of a brazing material (25) applied to an inner wall of the metal outer tube (12). The second joining portion (17B) overlaps the joining strip (18) and has a brazing length larger than a brazing length of the first joining portion (17A) which does not overlap the joining strip (18).