Capacitance Sensor Probe With Segmented Electrodes
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Solution Overview
Problem
Current capacitance-type liquid level sensors face challenges in achieving accurate, repeatable, and economical measurements due to limitations in sensor probe design, including part-to-part variation leading to measurement errors, susceptibility to bending and sloshing, and complex, costly arrangements.
Innovation Solution
A sensor probe design featuring two or more angularly arranged plate sections for each electrode, with spacers and fasteners to secure them in position, ensuring a thickness of less than 10 mm and electrical isolation to reduce noise and enhance sensitivity, while maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If concentric tube sensor probes are used to increase capacitance per unit height, then sensitivity in level measurements is improved, but manufacturing precision deteriorates due to part-to-part variation in tube dimensions
Solution Approach 1:
The sensor probe is divided into multiple discrete plate sections (first plate sections and second plate sections) that can be independently manufactured and then assembled. This segmentation allows each plate to be manufactured with standard tolerances rather than requiring tight tolerances on continuous tube dimensions, thereby improving manufacturing precision while maintaining the capacitance-based sensitivity.
Solution Approach 2:
A spacer component is introduced as an intermediary element between the first and second electrodes. The spacer maintains a consistent, controlled distance between the plate sections, eliminating the need for tight dimensional tolerances on the electrode plates themselves. This mediator component simplifies manufacturing while ensuring repeatable capacitance measurements.
2Ease of manufacture
If parallel plate-type sensor probes are used to reduce manufacturing cost, then ease of manufacture is improved, but reliability deteriorates due to bending and deformation from fuel sloshing
Solution Approach 1:
The electrode structure is segmented into multiple plate sections that are spaced apart and secured with fasteners. This segmented arrangement with mechanical fastening provides structural rigidity to resist bending from fuel sloshing, while each plate can still be manufactured using simple, cost-effective processes.
Solution Approach 2:
The plate sections are arranged in an angular relationship rather than being perfectly flat or curved. This angular arrangement with spacers creates a structured, rigid framework that resists deformation from sloshing forces while maintaining the capacitance measurement capability.
3Stability of the object's composition
If baffle plates are used to suppress liquid fuel movement, then stability of liquid fuel is improved, but device complexity increases and measurement accuracy deteriorates due to redirecting sloshing fuel flow
Solution Approach 1:
The plate sections serve dual functions: they act as both the electrode structure for capacitance measurement and as baffles to suppress fuel sloshing. By making the electrode structure itself serve the baffle function, the design eliminates the need for separate baffle components, thereby reducing device complexity while maintaining both measurement capability and fuel stability.
Solution Approach 2:
The electrode plates and baffle structures are merged into a single integrated component system. The first and second plate sections are arranged to serve both as measurement electrodes and as structural elements that prevent fuel sloshing, combining two functions into one structure to reduce overall complexity.
4Ease of manufacture
If electrode plates are made thinner to reduce cost, then ease of manufacture is improved, but strength deteriorates limiting resistance to bending
Solution Approach 1:
The electrode structure is divided into multiple plate sections that are spaced apart and mechanically fastened together. This segmentation allows each individual plate to be made thin and inexpensive while the assembled structure with fasteners provides the necessary strength and rigidity to resist bending from fuel sloshing.
Solution Approach 2:
The angular arrangement of plate sections with spacers creates a three-dimensional structured framework that provides structural strength without requiring each plate to be thick. The geometric arrangement itself contributes to the overall rigidity while allowing thin, cost-effective plate materials.
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 design provides improved sensitivity and accuracy in liquid level measurements, reduces manufacturing costs, and minimizes errors caused by sloshing and electrical noise, while maintaining structural integrity and reducing the impact of part-to-part variation.
Implementation Method 1
The sensor probe comprises a pair of electrodes that form a capacitor having the liquid and/or air between them acting as a dielectric. As the level of the liquid in the container varies the effective dielectric constant between the electrodes changes, which changes the capacitance of the sensor probe.
Implementation Method 2
a capacitor having the liquid and/or air between them acting as a dielectric
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Sensor probes for capacitance-type liquid level sensors do not comprise an acceptable balance between cost, performance and durability for mobile applications. An improved sensor probe is provided. A first electrode comprises two or more first plate sections arranged in angular relationship with respect to each other. A second electrode comprises two or more second plate sections arranged in angular relationship with respect to each other. Spacers are located between the first and second electrodes such that each first plate section is spaced apart in parallel and substantially overlapping relationship with respective second plate sections. Fasteners securely fix the first and second electrodes in position.