Permittivity Sensing for Cable Sheath Filling Defect Detection
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Solution Overview
Problem
Existing methods fail to reliably ensure that filling material fills the entire space within a sheath in mechanical or civil construction, particularly at locations inaccessible due to embedding in concrete, leading to potential air pockets that can deteriorate the cable.
Innovation Solution
A permittivity sensor with a sleeve containing electrodes in an annular air gap, protected by outer and inner tubes, measures permittivity variations to detect the presence, nature, and level of filling material, using a control unit to convert signals into permittivity values, allowing real-time monitoring and correction of filling defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the sheath is embedded in a concrete solid body, then the structure gains strength and stability, but access to the sheath interior becomes impossible for monitoring filling material
Solution Approach 1:
The patent introduces an intermediary measurement system (electrodes and control unit) that can detect filling material properties through the sheath wall without requiring direct access to the sheath interior. This mediator enables monitoring while the sheath remains embedded in concrete.
Solution Approach 2:
The patent replaces mechanical access methods (physical inspection, sampling) with electromagnetic field-based measurement. The control unit uses electrical signals to detect permittivity changes, substituting mechanical intervention with field-based sensing through the sheath wall.
2Ease of operation
If traditional filling monitoring methods are used, then the pouring operation can be observed at accessible points, but air pockets at inaccessible locations cannot be detected
Solution Approach 1:
The patent introduces an intermediary measurement system (electrodes and control unit) that can detect filling material properties through the sheath wall without requiring direct access to the sheath interior. This mediator enables monitoring while the sheath remains embedded in concrete.
Solution Approach 2:
The patent replaces mechanical access methods (physical inspection, sampling) with electromagnetic field-based measurement. The control unit uses electrical signals to detect permittivity changes, substituting mechanical intervention with field-based sensing through the sheath wall.
3Measurement precision
If electrodes are directly exposed in the filling material, then measurement can be performed, but electrode protection and measurement reliability are compromised
Solution Approach 1:
The patent introduces an intermediary measurement system (electrodes and control unit) that can detect filling material properties through the sheath wall without requiring direct access to the sheath interior. This mediator enables monitoring while the sheath remains embedded in concrete.
Solution Approach 2:
The patent replaces mechanical access methods (physical inspection, sampling) with electromagnetic field-based measurement. The control unit uses electrical signals to detect permittivity changes, substituting mechanical intervention with field-based sensing through the sheath wall.
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
Ensures complete filling of the sheath by detecting air pockets and material quality, preventing cable deterioration, and enabling real-time adjustments during construction, thereby enhancing the reliability and longevity of the structure.
Implementation Method 1
measure a signal between a first electrode and a second electrode of the plurality of electrodes, the second electrode being circumferentially adjacent to the first electrode; and convert the signal into a permittivity value
Data Source
Figure 1~3
Figure 4
Figure 5
AI summary
Methods and sensors for detecting permittivity in an inner cavity (13) of a sleeve (10) with the aim of establishing the quality and quantity of filling material (6) within a sheath (2) of a cable for a bridge construction.