Stainless Steel Refrigerant Pipe Joint for Fluxless Brazing Strength
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Solution Overview
Problem
Existing refrigerant pipes face strength deterioration issues in high-temperature environments due to furnace brazing of copper tubes, leading to potential deformation during transportation and assembly, and require flux removal to prevent contamination of refrigerant.
Innovation Solution
A refrigerant pipe design featuring a stainless steel pipe body with a copper or copper alloy connecting tube, where the connecting tube is overlapped with the pipe body in the pipe diameter direction to compensate for strength deterioration, and furnace brazing is used without flux to inhibit sensitization and ensure reliable connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If furnace brazing is used to join copper tube and stainless steel tube, then reliable connection is achieved, but strength deterioration and deformation occur during transportation and assembly
Solution Approach 1:
The refrigerant pipe is divided into three distinct segments: stainless steel tube (11), copper tube (12), and intermediate tube (13). This segmentation allows each material to perform its optimal function while reducing overall sensitization. The intermediate tube acts as a buffer zone that prevents direct high-temperature exposure of the copper tube to the furnace brazing process, thereby maintaining strength while achieving reliable connection.
Solution Approach 2:
The intermediate tube (13) made of stainless steel or nickel acts as a mediator between the copper tube (12) and the furnace brazing process. It shields the copper tube from direct high-temperature exposure, preventing strength deterioration and deformation. The intermediate tube enables reliable connection while protecting the copper tube's mechanical properties.
2Reliability
If furnace brazing is used to join copper tube and stainless steel tube, then connection is achieved, but flux must be removed to prevent refrigerant contamination
Solution Approach 1:
The intermediate tube (13) enables the use of fluxless furnace brazing by acting as a barrier that protects the copper tube from flux contamination. This intermediary structure allows reliable connection to be achieved without the need for flux removal operations, simplifying the manufacturing process and preventing refrigerant contamination.
Solution Approach 2:
The intermediate tube creates a protected environment during brazing that eliminates the need for flux. By using fluxless furnace brazing in this controlled configuration, the patent avoids the harmful effects of flux residues on refrigerant purity while maintaining connection reliability.
3Reliability
If copper tube is directly brazed to stainless steel tube, then connection is achieved, but sensitization occurs leading to strength loss
Solution Approach 1:
The direct connection between copper tube and stainless steel tube is segmented by introducing an intermediate tube. This segmentation prevents the copper tube from direct exposure to high-temperature brazing conditions that cause sensitization, thereby maintaining material composition stability while achieving reliable connection.
Solution Approach 2:
The intermediate tube serves as a mediator that isolates the copper tube from the high-temperature brazing environment. This intermediary structure prevents sensitization of the copper tube by blocking direct thermal exposure, thus preserving material composition stability while enabling reliable connection between dissimilar metals.
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 design enhances the strength and reliability of the refrigerant pipe by preventing deformation and ensuring the connecting tube's strength is supported by the pipe body, while eliminating the need for flux, thus maintaining refrigerant purity and reducing manufacturing costs.
Implementation Method 1
This joining method includes joining the stainless steel tube and the copper tube by furnace brazing.
Data Source
AI summary
A refrigerant pipe constituting a refrigerant circuit of a refrigeration apparatus, includes: a pipe body made of stainless steel; and a first connecting tube made of copper or a copper alloy and that is configured to connect a first different refrigerant pipe to the refrigerant pipe. The first connecting tube is connected to an outer circumferential surface of a first end of the pipe body in a pipe axis direction of the pipe body. The first connecting tube overlaps with the pipe body in a pipe diameter direction in an entirety of the first connecting tube in the pipe axis direction.