Capacitive Fluid Sensor for Deep Fryer Heat Interlock Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing control systems for heat sources in cooking environments, such as deep fryers, face challenges with fluid level sensing due to debris and viscosity issues, leading to inaccurate float-based sensors and capillary sensor failures, which can result in unsafe operation or unsanitary conditions.
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 interlock control, ensuring reliable and sanitary operation across a wide range of fluid viscosities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If float-based level sensors are used to detect fluid level, then the sensor structure is simple, but the sensor becomes stuck due to debris in the fluid creating impediments to the float riding freely along the shaft
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 interactions with the fluid, eliminating mechanical moving parts that can become stuck on debris. This substitution maintains simplicity while dramatically improving reliability in debris-containing environments.
Solution Approach 2:
The patent introduces a capacitive sensor as an intermediary detection mechanism that senses fluid level through electrical capacitance changes rather than direct mechanical contact. The sensor measures the dielectric properties of the fluid to determine level, using the fluid itself as part of the capacitive circuit rather than requiring mechanical float movement.
2Measurement precision
If capillary sensors are used to detect fluid level, then the sensor can sense fluid level through capillary action, but the sensor fails when fluid viscosity is high or fluid is in partially solid phase
Solution Approach 1:
The patent changes the sensing parameter from capillary action (which depends on fluid viscosity and surface tension) to electrical capacitance measurement. The capacitive sensor detects changes in dielectric constant and capacitance values as the fluid level changes, which are not affected by viscosity or phase state. This allows the sensor to accurately measure fluid levels across a wide range of viscosities including partially solid phases.
3Measurement precision
If capillary sensors are used to detect fluid level, then the sensor can determine fluid presence, but fluid is retained in the capillary creating unsanitary conditions that are difficult to clean
Solution Approach 1:
The patent replaces the capillary tube structure with a capacitive sensing element that detects fluid level through electrical field interactions. The sensor does not require fluid to enter or fill a physical tube, eliminating the creation of hard-to-clean cavities. The sensing element can be easily wiped or rinsed without retaining fluid in internal passages.
4Measurement precision
If capillary sensors are used to detect fluid level, then the sensor can measure fluid presence, but air pockets or bubbles retained within the capillary are subject to temperature changes causing sensor failure
Solution Approach 1:
The patent uses the fluid's dielectric properties as an intermediary for detection rather than requiring physical fluid contact in a confined space. The capacitive sensor detects changes in the electrical field caused by the presence or absence of fluid, without trapping air pockets in capillary spaces. This eliminates the temperature-induced expansion/contraction problems that cause sensor failure in capillary-based systems.
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, preventing unsafe heating conditions and maintaining sanitation by reliably distinguishing between fluid and air, enabling safe operation and easy cleaning.
Implementation Method 1
A capacitive sensor system that determines fluid presence and level by measuring capacitance between the sensor and the container walls
Implementation Method 2
The sensor is configured to detect the presence of oil within the frypot when a level of oil within the frypot is at or above the level of the sensor
Data Source
AI summary
A capacitive sensor and control system is configured to detect the presence (or absence) of fluid within a container. Configured in a vat or frypot of a deep fryer, the sensor determines when a level of liquid within the frypot is at or above the level of the sensor. The sensor is in communication with the control system and the sensor sends a signal to the control system representative of the presence or absence of liquid within the frypot and at the level of the sensor. The controller receives the signal from the sensor, and allows operation of the one or more heat sources for heating the frypot when the signal received from the sensor is representative of liquid being disposed within the frypot at or above the level of the sensor, and prevents operation of the one or more heat sources when the signal received from the sensor indicates that liquid is not disposed within the frypot at or above the level of the sensor.