Wireless Passive Strain Sensor for Rotating Shafts
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Solution Overview
Problem
Conventional strain sensors for dynamic rotating shafts require batteries or wireless transmission modules, which occupy space and interfere with the shaft's rotation, causing measurement inaccuracies and complicating installation.
Innovation Solution
A wireless passive strain sensor comprising an outer coil holder, reading inductance coil, capacitance patch, inner coil holder, and sensing inductance coil, where the shaft penetrates through the outer holder, and the capacitance patch is attached to the shaft, allowing for wireless measurement without batteries or shaft modifications, using a bearing structure and interdigital capacitor for resonance frequency scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a sensor with battery or wireless transmission module is mounted on the shaft, then wireless measurement capability is achieved, but the sensor occupies space and interferes with shaft rotation
Solution Approach 1:
The sensor system is divided into two separate parts: a passive sensing element mounted on the shaft (inner coil holder with sensing coil) and an external reading device (outer coil holder with reading coil). This segmentation allows the shaft-mounted component to be minimal and non-interfering while maintaining wireless measurement capability through electromagnetic coupling between the two coils.
Solution Approach 2:
The active electronic components (battery, wireless transmission module) are extracted from the shaft-mounted sensor and relocated to an external reading device. The shaft-mounted sensing element becomes purely passive, consisting only of the inner coil holder and sensing coil, thereby eliminating space occupation and interference with shaft rotation.
2Ease of operation
If a sensor with battery or wireless transmission module is mounted on the shaft, then wireless measurement capability is achieved, but connecting lines become entangled during rotation
Solution Approach 1:
All connecting lines and wiring are extracted from the shaft-mounted sensor and relocated to the external reading device. The shaft-mounted sensing element requires no electrical connections, eliminating the harmful effect of connecting line entanglement during shaft rotation entirely.
Solution Approach 2:
The mechanical connection system (wires and cables) is replaced with an electromagnetic field-based wireless transmission system. The sensing coil on the shaft and reading coil on the external device communicate through electromagnetic induction, eliminating the need for physical connecting lines that would become entangled.
3Ease of manufacture
If the shaft is modified for sensor installation, then sensor mounting is achieved, but the shaft's original structure and properties are altered
Solution Approach 1:
The sensor mounting requirements are extracted from the shaft itself and transferred to a separate, non-intrusive mounting structure (outer coil holder). The shaft remains unmodified, preserving its original structure, material properties, and mechanical integrity, while the sensor system is mounted externally using the holder that can be attached without altering the shaft.
4Measurement precision
If a conventional sensor is mounted on the shaft, then strain measurement is achieved, but measurement accuracy is reduced due to sensor interference
Solution Approach 1:
The sensing element is extracted to be completely passive and non-interfering, mounted on the shaft without adding significant mass or mechanical complexity. The actual measurement function is performed externally by the reading device, eliminating the harmful interference that active sensors would cause on the rotating shaft while maintaining strain measurement capability through electromagnetic coupling.
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 accurate, space-efficient, and easy measurement of shaft strain without tangling or modifying the shaft, allowing for instantaneous data acquisition and reducing operational complexity.
Implementation Method 1
The sensing inductance coil is wrapped around the inner coil holder... The antenna analyzer is configured to scan a resonance frequency of the reading inductance coil corresponding to the sensing inductance coil
Implementation Method 2
a bearing structure includes a plurality of ball bearings... The ball bearings are polyoxymethylene (POM) plastic bearings
Data Source
AI summary
A wireless passive strain sensor is provided. The wireless passive strain sensor includes an outer coil holder, a reading inductance coil, a capacitance patch, an inner coil holder, and a sensing inductance coil. A shaft penetrates through the outer coil holder. The reading inductance coil is disposed on the outer coil holder. The capacitance patch is disposed on the shaft. The inner coil holder is disposed inside the outer coil holder. The inner coil holder is disposed on the shaft. The sensing inductance coil is disposed on the inner coil holder. The sensing inductance coil is electrically connected to the capacitance patch.