Vacuum Insulated Structure Fitting Attachment Using Intermediary Hub
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Solution Overview
Problem
Vacuum insulated structures with thin tube and jacket walls face challenges in affixing fittings without damaging the vacuum seal or perforating the walls, as traditional welding or soldering methods risk destroying the seal and the thin walls cannot support threaded or compression-type fittings.
Innovation Solution
A method involving a two-step brazing process to form a seal and affix a fitting to a vacuum insulated structure, where a first brazing process seals the vent to preserve the vacuum, and a second process attaches the fitting to the tube or jacket using a flux-free braze material to prevent acid erosion and ensure structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional welding or soldering is used to affix a fitting to the tube wall or jacket wall, then the fitting can be attached, but the thin wall is perforated and the vacuum seal is destroyed
Solution Approach 1:
A thickened section or hub is provided on the jacket or tube that serves as an intermediary structure. This hub has a thickness greater than the standard wall thickness, providing a robust attachment surface for the fitting while maintaining the thin-walled vacuum insulation elsewhere. The fitting is affixed to this intermediary hub rather than directly to the thin wall, thus preventing wall perforation and preserving the vacuum seal.
2Ease of manufacture
If acid-containing solder material is used to attach the fitting, then the fitting can be affixed, but the acid erodes into and eventually perforates the thin outer jacket wall
Solution Approach 1:
The thickened hub acts as a physical barrier and intermediary between the fitting attachment area and the thin jacket wall. By providing this intermediate structure with greater thickness, the harmful acid from soldering or brazing materials is contained and its erosive effect is limited to the hub area, preventing it from reaching and perforating the thin outer jacket wall that maintains the vacuum seal.
3Use of energy by moving object
If the tube and jacket walls are made thin to reduce weight and improve insulation, then insulation efficiency increases, but the walls cannot support threaded or compression-type fittings without sustaining damage
Solution Approach 1:
The structure is segmented into two distinct zones: the thin-walled vacuum insulation section (tube and jacket) for optimal thermal insulation, and a localized thickened hub section for structural support. This segmentation allows each part to be optimized for its specific function - the thin walls for insulation efficiency and the thick hub for fitting support - without compromising either requirement.
Solution Approach 2:
The wall thickness is not uniform throughout the structure but varies locally. The majority of the tube and jacket maintains thin walls for optimal insulation, while a specific localized region (the hub) has increased thickness to provide the necessary structural strength for supporting fittings. This local quality change allows the structure to meet both insulation and strength requirements simultaneously.
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
Enables the secure attachment of fittings to vacuum insulated structures without compromising the vacuum seal, allowing for effective mounting and support while preventing damage to the thin walls, thus maintaining the structural integrity and insulation efficiency.
Implementation Method 1
A seal is formed between the end of the jacket and the outer wall of the tube to preserve a vacuum within the insulating space. In one variation, the seal is formed by a first brazing process
Implementation Method 2
the fitting is affixed by a second brazing process. Alternatively, the two brazing processes may be performed sequentially, first sealing the vent and then affixing the fitting
Data Source
AI summary
A vacuum insulated structure including a tube having an outer wall, a jacket surrounding the tube to enclose an annular insulating space, the jacket having an end that terminates at the outer wall of the tube, a seal formed between the end of the jacket and the tube to preserve a vacuum within the insulating space, and a fitting affixed to one of the tube and the jacket for coupling the vacuum insulated structure to an external device. A method of making a vacuum insulated structure including forming a tube and a jacket, positioning the jacket over the tube to form an annular insulating space, with an end of the jacket being positioned adjacent to an outer wall of the tube to form a vent, causing air to escape through the vent, sealing the vent, and affixing a fitting to one of the tube and the jacket.