Stacking Header Space Configuration for Brazed Joint Fillets
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Solution Overview
Problem
Existing stacking type headers face challenges in forming fillets at intended joint portions between flat tubes and plates, leading to low joining strength and inadequate brazing material distribution, which affects the performance of heat exchangers and heat pump devices.
Innovation Solution
The configuration of spaces around flat tubes, clad members, and bare members is optimized to increase the size of these spaces from contact boundary surfaces towards the flat tubes, allowing for the formation of fillets at intended joint portions, enhancing the joining strength by directing brazing material flow through capillary action.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sectional area of communication holes decreases from the contact boundary surface toward the flat tubes, then positioning of flat tube ends is achieved and entrance of brazing material into tubes is prevented, but molten brazing material flows below the flat tubes and fillets cannot be formed on upper parts
Solution Approach 1:
The patent applies local quality by creating different space configurations in different regions: a first space above the flat tube with larger volume to collect and form fillets, and a second space below the flat tube with smaller volume to prevent excessive brazing material flow. This local differentiation of space characteristics enables simultaneous achievement of fillet formation and prevention of brazing material intrusion.
2Ease of operation
If a tapered shape only in width direction is employed from the contact boundary surface toward the flat tube end, then positioning is achieved, but fillets cannot be formed over the entire circumferential area and joining strength is low
Solution Approach 1:
The patent transitions from a two-dimensional tapered shape (width direction only) to a three-dimensional space configuration by introducing height dimension variations. The first space extends upward from the contact boundary surface with sufficient volume to allow complete circumferential fillet formation, while the second space is constrained downward. This dimensional expansion enables comprehensive fillet coverage around the entire flat tube circumference.
3Ease of operation
If the end of the flat tube and the inclined portions contact at points, then positioning is achieved, but fillets cannot be formed at the contact boundary surfaces
Solution Approach 1:
The patent introduces the first space as an intermediary region between the flat tube end and the upper boundary, and the second space as an intermediary region between the flat tube end and the contact boundary surface. These intermediary spaces ensure continuous contact and heat transfer pathways, enabling fillet formation at the contact boundary surfaces while maintaining precise positioning.
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 ensures the formation of fillets over the entire circumferential area of flat tubes, increasing joining strength and reducing the amount of brazing material required, while preventing excessive material from flowing into the tubes, thus improving the structural integrity and efficiency of heat exchangers and heat pump devices.
Implementation Method 1
allowing for the formation of fillets at intended joint portions, enhancing the joining strength by directing brazing material flow through capillary action
Data Source
Figure 1
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AI summary
In a stacking type header 10, in a state in which flat tubes 20 are inserted into openings 12A in a bare member 12 and in which ends 20A of the flat tubes 20 are in contact with stoppers 12B, spaces 30 are formed at positions surrounded by the flat tubes 20, a clad member 11, and the bare member 12. The spaces 30 each include a first space 30a formed in a vicinity of a contact boundary surface between the flat tube 20 and the clad member 11, a second space 30b smaller than, at least, the first space 30a and formed in a vicinity of a contact boundary surface between the bare member 12 and the clad member 11, and a third space 30c smaller than, at least, the first space 30a and formed in a vicinity of a contact boundary surface between the bare member 12 and the flat tube 20.