Double-Sheath Coaxial Cable Hermetic Sealing Against Moisture Noise
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Solution Overview
Problem
Coaxial cables with a double sheath structure are prone to moisture ingress in humid environments, leading to reduced insulation resistance and signal noise, especially when the gap between the sheaths is open, which can persist until moisture is removed.
Innovation Solution
Incorporating a second airtight portion that hermetically seals between the inner and outer sheaths, using metal mounting portions and an insulating portion made of inorganic materials like Al2O3 or SiO2, to prevent moisture entry and maintain insulation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gap between the first sheath and the second sheath is left open, then electrical floating is realized and signal noise is reduced, but moisture may enter the gap in humid environments, lowering insulation resistance and causing signal noise
Solution Approach 1:
A second airtight portion is introduced as an intermediary element between the first sheath and the second sheath. This airtight portion fills the gap that would otherwise be left open, preventing moisture ingress while maintaining the electrical floating configuration. The airtight portion acts as a mediator that allows both the open electrical state and moisture protection to coexist.
2Reliability
If a second airtight portion is added to prevent moisture ingress, then insulation resistance is maintained, but device complexity increases
Solution Approach 1:
The second airtight portion is designed to serve multiple functions simultaneously: it provides moisture protection, maintains electrical floating between sheaths, and seals the powdered insulating material in place. By making this single component multi-functional, the patent reduces the need for additional separate elements, thereby limiting the increase in device complexity.
3Ease of manufacture
If the coaxial cable uses a double sheath structure with open gap, then manufacturing is simplified, but signal noise generation increases in humid environments
Solution Approach 1:
The second airtight portion is incorporated during the manufacturing process to pre-prevent moisture ingress before the cable is deployed in humid environments. This preliminary protective action ensures that the cable maintains its insulation resistance and does not generate signal noise due to moisture, while still allowing the manufacturing process to follow the simplified double sheath structure.
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 second airtight portion effectively prevents external moisture from entering the insulating material, reducing signal noise and maintaining insulation resistance, and can be enhanced by vacuuming or replacing the gas inside to further improve insulation.
Implementation Method 1
a second airtight portion that hermetically seals between an inner sheath and a sheath on an outer side of the inner sheath
Implementation Method 2
a powdered insulating material that is filled between the core wire and an innermost sheath and between the plurality of sheaths
Data Source
AI summary
According to one embodiment, a coaxial cable includes a core wire, a plurality of sheaths which are tubular and made of metal and coaxially cover the core wire, a powdered insulating material which is filled between the core wire and an innermost sheath and between the plurality of sheaths, respectively, a first airtight portion which hermetically seals between the core wire and an inner sheath, and a second airtight portion which hermetically seals between the inner sheath and the sheath on an outer side of the inner sheath.