Apertured Capacitive Sensor for Rotary Machine Air Gap Measurement
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Solution Overview
Problem
Capacitive sensors in rotating machines face challenges in fitting within limited spaces and minimizing ventilation obstruction, which affects their signal-to-noise ratio and measuring range, particularly in applications where the sensor's presence hinders cooling gas flow through stator ventilation slots.
Innovation Solution
The capacitive sensor design incorporates apertures across its thickness, allowing for improved ventilation while maintaining or enhancing the signal-to-noise ratio, thereby increasing the measuring range and remoteness distance of electronic hardware without excessive obstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a capacitive sensor with a flat sensing body is used to fit into limited space, then the sensor can be installed on the stator surface, but it obstructs ventilation slots and reduces cooling gas flow efficiency
Solution Approach 1:
The sensing body is designed with multiple apertures distributed across its surface, creating a porous structure that allows cooling gas to pass through. This enables the sensor to maintain its flat configuration for space efficiency while minimizing obstruction to ventilation slots, as gas can flow through the apertures rather than being completely blocked.
Solution Approach 2:
The sensing body is divided into multiple segments by creating apertures that split the continuous structure. This segmentation allows the sensor to maintain electrical functionality while creating pathways for cooling gas flow, resolving the contradiction between occupying space and hindering ventilation.
2Productivity
If the sensing area of the capacitive sensor is reduced to minimize ventilation obstruction, then cooling gas flow is improved, but the signal to noise ratio decreases and measuring range is reduced
Solution Approach 1:
The apertures are strategically positioned and sized to minimize impact on both ventilation and signal quality. The local quality of the sensing body is optimized by creating apertures that allow gas flow while preserving sufficient conductive material for maintaining an adequate signal to noise ratio, thus resolving the contradiction between ventilation efficiency and measurement precision.
3Reliability
If the remoteness distance of electronic hardware from the rotating machine is increased to protect from harsh environment, then hardware protection is improved, but cable length increases and electromagnetic accuracy deteriorates
Solution Approach 1:
The capacitive sensor utilizes the dielectric properties of the air gap as a parameter to extend the measuring range. By optimizing the sensor's electrical characteristics and utilizing the apertured structure to maintain signal quality over longer distances, the system can achieve both increased remoteness distance for hardware protection and maintained electromagnetic accuracy through proper parameter selection and optimization.
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 apertured capacitive sensor design reduces ventilation hindrance and can improve signal-to-noise ratio, allowing for increased measuring range and longer cable lengths without compromising cooling gas flow efficiency.
Implementation Method 1
Capacitive sensors, sometimes referred to as dielectric sensors, use capacitance to measure the dielectric permittivity of a surrounding medium. An oscillating electrical field can be generated between conductive elements of a sensing body, and changes in dielectric constant of surrounding media can be detected by changes in the operating frequency.
Implementation Method 2
Capacitive sensors, sometimes referred to as dielectric sensors, use capacitance to measure the dielectric permittivity of a surrounding medium.
Implementation Method 3
forming apertures across the thickness of a sensing body of a capacitive sensor could allow not only to reduce the hindrance to ventilation caused by its presence by allowing ventilation through the apertures
Data Source
AI summary
The capacitive sensor can have a sensing body having two flat conductor elements positioned parallel to one another and held spaced apart from one another, and having a thickness normal to the flat conductor elements, the sensing body having at least one aperture formed across its thickness. The capacitive sensor can be used to measure an air gap between a stator and rotor of a rotary electric machine, and the presence of the apertures can facilitate ventilation and/or improve linearization process of capacitive sensor through redistribution of its current vs distance signal along the measuring range, thus potentially increasing signal to noise ratio where it is the challenging to do so.