DPTSS Fiber Cable Pressure Blocking Segments
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Solution Overview
Problem
Conventional fiber optic cables with metal sheathing tubes face challenges in accurately measuring pressure distributions due to pinholes, tangles, and non-uniform clearance spaces, which affect pressure and strain measurements, and the use of water-dissolvable resin coats can lead to incomplete dissolution and inconsistent measurement results.
Innovation Solution
A fiber optic cable design featuring an optical fiber sheathing metal tube with a multilayer strand structure and pressure blocking sections with through holes, allowing for uniform clearance and accurate pressure distribution measurement by isolating pressure propagation and eliminating the need for water-dissolvable resins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional fiber optic cable with a sealed metal sheathing tube is used, then the cable has good sealing performance and mechanical strength, but it cannot accurately measure pressure distribution because the optical fiber is not exposed to external pressure
Solution Approach 1:
The metal sheathing tube is segmented into sealed sections and pressure-exposed sections. The sealed sections maintain structural integrity and sealing performance, while the pressure-exposed sections allow optical fibers to contact external pressure. This segmentation resolves the contradiction by spatially separating the functions of sealing and pressure sensing.
Solution Approach 2:
Different sections of the metal sheathing tube have different properties: some sections are sealed to provide mechanical strength and sealing, while other sections are opened to allow pressure exposure for measurement. This local differentiation of properties allows the cable to simultaneously achieve good sealing performance and accurate pressure measurement.
2Measurement precision
If the metal sheathing tube is opened to expose optical fibers to pressure, then pressure measurement becomes possible, but pinholes and structural weaknesses affect measurement accuracy
Solution Approach 1:
The sheathing tube is divided into multiple sealed sections connected by pressure-exposed segments. This segmentation allows the majority of the tube to remain sealed and structurally sound, while only specific segments are opened for pressure sensing, minimizing the impact of pinholes and maintaining overall reliability.
Solution Approach 2:
The design anticipates the presence of pinholes by creating redundant sealed sections. If pinholes exist in pressure-exposed sections, the sealed sections maintain structural integrity and provide backup measurement paths, cushioning against measurement failure and maintaining reliability.
3Manufacturing precision
If water-dissolvable resin is used to create clearance space, then uniform clearance can be achieved, but incomplete dissolution leads to inconsistent measurement results
Solution Approach 1:
The problematic water-dissolvable resin is completely removed by dissolution, extracting the temporary spacing aid after it has served its manufacturing purpose. This complete removal eliminates the source of measurement inconsistency while retaining the benefit of uniform clearance space created during manufacturing.
Solution Approach 2:
The water-dissolvable resin serves as a temporary intermediary substance during manufacturing that creates uniform clearance space, then dissolves completely to leave no residue. This intermediary approach allows precise clearance control during manufacturing without compromising measurement consistency during operation.
4Measurement precision
If pressure blocking sections are added to isolate pressure propagation, then accurate pressure distribution measurement is improved, but device complexity increases
Solution Approach 1:
The cable is segmented into modular sections with standardized sealed and pressure-exposed portions. This segmentation allows pressure blocking to be achieved through simple repetition of modular units rather than complex integrated designs, reducing overall device complexity while maintaining measurement precision.
Solution Approach 2:
Instead of creating continuous pressure isolation barriers throughout the cable, the design inverts the approach by allowing pressure propagation in sealed sections and blocking it only where measurement is not needed. This inversion simplifies the structure by eliminating unnecessary pressure blocking elements while maintaining measurement accuracy.
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 enhances measurement accuracy for pressure, temperature, and strain distributions by preventing pressure interference and ensuring consistent Brillouin scattering frequency measurements, overcoming issues with pinholes and resin incomplete dissolution.
Implementation Method 1
measuring a pressure distribution of a measurement target on the basis of frequency changes of Brillouin scattering of laser light entered into the sensor optical fiber
Implementation Method 2
measuring a temperature distribution along the axial (longitudinal) direction of the optical fiber cable
Implementation Method 3
measuring distributions of temperature, pressure, and strain
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A DPTSS fiber optic cable (100) includes an optical fiber sheathing cylindrical metal tube (3) accommodating a pressure sensor optical fiber (1) and having a plurality of through holes (8) formed therein; and pressure blocking sections (11) formed at intervals in the axial direction of the cable.