Capacitive Sensor Probe for Debris-Resistant Fluid Level Detection
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Solution Overview
Problem
Existing fluid level sensors in cooking systems, such as deep fryers, face issues with debris interference and viscosity changes, leading to inaccurate readings and unsanitary conditions, particularly with capillary sensors.
Innovation Solution
A capacitive sensor system that determines fluid presence and level by measuring capacitance between the sensor and the container walls, using a capacitive sensor probe and electronics to communicate with a microcontroller for controlling heating systems, ensuring reliable and sanitary operation across various viscosities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a float-based level sensor is used to directly sense fluid level, then the sensor can provide continuous level indication, but debris in the fluid causes the float to stick on the shaft, leading to inaccurate readings
Solution Approach 1:
The patent replaces the mechanical float-based level sensing system with a capacitive sensing system. The capacitive sensor detects fluid level through electrical field interaction with the fluid, eliminating mechanical components that are susceptible to debris interference and sticking. This substitution of mechanical detection with electrical field-based detection resolves the reliability issue while maintaining measurement capability.
Solution Approach 2:
The capacitive sensor acts as an intermediary between the fluid and the measurement system. Instead of direct mechanical contact between the float and fluid, the capacitive sensor measures changes in capacitance caused by the fluid's presence and properties, providing indirect but reliable measurement that is not affected by debris in the fluid.
2Measurement precision
If a capillary sensor is used to sense fluid level, then the sensor can determine level based on fluid location in the tube, but differences in fluid viscosity prevent capillary action from working effectively, especially with partially solid fluids
Solution Approach 1:
The patent replaces the capillary action-based mechanical sensing mechanism with an electrical field-based capacitive sensing mechanism. Capacitive sensors measure fluid presence and properties through changes in electrical capacitance, which is not dependent on fluid viscosity or capillary action. This allows the sensor to accurately measure fluid levels and properties across a wide range of viscosities, including partially solid fluids that would not work with capillary sensors.
Solution Approach 2:
The patent changes the measurement parameter from mechanical capillary rise (which depends on viscosity) to electrical capacitance (which is affected by fluid dielectric properties). By measuring capacitance changes rather than relying on capillary action, the sensor can detect fluid presence and characteristics regardless of viscosity variations, enabling operation with fluids of any consistency.
3Measurement precision
If a capillary sensor is used in a cooking environment, then the sensor can measure fluid level, but fluid retention in the capillary creates unsanitary conditions that are difficult to clean
Solution Approach 1:
The patent replaces the capillary tube structure with a capacitive sensor design that does not require fluid to enter or fill internal passages. The capacitive sensor measures fluid properties through electrical field interaction from the outside, eliminating internal cavities where fluid could be retained. This design allows for easy sanitation and cleaning, as the sensor surface can be readily wiped or washed without trapping fluid inside complex internal structures.
4Temperature
If a capillary sensor is exposed to extreme temperature changes, then the sensor can operate in cooking environments, but air pockets or bubbles retained within the capillary are subject to temperature changes that cause sensor failure
Solution Approach 1:
The patent replaces the capillary tube structure with a capacitive sensor that does not trap air pockets or bubbles within its structure. The capacitive sensor measures fluid properties through electrical field interaction without requiring fluid to fill internal passages, eliminating the source of temperature-related failures. This design maintains reliability across extreme temperature ranges by removing the vulnerable air-filled capillary structure.
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 capacitive sensor system provides accurate fluid level detection and prevents heating system operation when insufficient fluid is present, ensuring safe and efficient cooking or cleaning processes while maintaining a clean environment.
Implementation Method 1
A capacitive sensor system that determines fluid presence and level by measuring capacitance between the sensor and the container walls
Data Source
AI summary
A capacitive sensor includes a metal radiator disposed at an extreme end of a sensor assembly. A coaxial electrode is electrically interconnected to the metal radiator. The coaxial electrode has a center conductor, a dielectric around the center conductor, and an outer conductor, the center conductor being in electrical continuity with the metal radiator. An insulator configured to fit adjacent the metal radiator is configured to electrically and thermally isolate the metal radiator from selected electrical and thermal properties in an environment wherein the capacitive sensor probe is disposed. A connector is disposed distal from the metal radiator on the coaxial electrode, a portion of the connector being in electrical continuity with the metal radiator.