Level sensor for a bulk dispense tank in a washing machine appliance
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Solution Overview
Problem
Existing washing machine systems face challenges in accurately measuring the remaining level of fluid additives like detergents and fabric softeners due to interference with optical, conductivity, and traditional float sensors, leading to inaccurate readings and operational inefficiencies.
Innovation Solution
A washing machine design incorporating a bulk dispense tank with a level sensor system that includes a tether, float body, and circuit board with accelerometer and gyroscope chips, allowing for precise measurement of fluid additive levels without the limitations of traditional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional float sensors are used to measure fluid additive levels, then the structure is simple and easy to manufacture, but the float can clog with detergent and fabric softener such that the float is immobile, leading to inaccurate readings
Solution Approach 1:
The patent replaces the traditional mechanical float sensor with a magnetic field-based sensing system. A magnet is attached to the float, and a reed switch or Hall effect sensor detects the magnetic field position to determine fluid level. This substitution eliminates mechanical contact with the fluid, preventing clogging while maintaining the float mechanism's simplicity.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the float and the sensor. The magnet on the float creates a magnetic field that acts as a mediator, allowing the reed switch or Hall effect sensor to detect float position without direct physical contact with the fluid, thus avoiding clogging issues.
2Ease of operation
If optical sensors are used to measure fluid additive levels, then non-contact measurement is achieved, but detergent and fabric softener create a film over the sensor that causes false readings
Solution Approach 1:
The patent replaces optical sensors with magnetic field-based sensors (reed switches or Hall effect sensors). The magnetic field penetrates the tank wall and is not affected by films created by detergent or fabric softener, eliminating the measurement errors caused by optical interference while maintaining non-contact measurement capability.
Solution Approach 2:
The patent changes the detection parameter from optical properties (which are affected by films) to magnetic field properties (which are not affected by films). The magnet on the float generates a magnetic field that can be detected through the tank wall by magnetic sensors, providing accurate readings regardless of fluid composition or film formation.
3Measurement precision
If conductivity sensors are used to measure fluid additive levels, then electrical measurement is achieved, but a film of detergent or fabric softener can bridge the probes and such sensors are susceptible to electrical noise
Solution Approach 1:
The patent replaces conductivity sensors with magnetic field-based sensors. The magnetic field detection method is not susceptible to electrical noise and is not affected by conductive films formed by detergent or fabric softener, eliminating the harmful electrical interference issues while maintaining precise measurement capability.
4Ease of operation
If capacitive sensors are used to measure fluid additive levels, then contactless measurement is achieved, but a precise wall thickness is required to measure the level accurately and tank wall thickness is difficult to control
Solution Approach 1:
The patent replaces capacitive sensors with magnetic field-based sensors (reed switches or Hall effect sensors). The magnetic field method is less sensitive to variations in tank wall thickness compared to capacitive sensing, as magnetic fields penetrate materials more predictably and are not as strongly affected by the dielectric properties and thickness variations of tank walls.
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
This solution provides accurate and reliable measurement of fluid additive levels, ensuring optimal washing machine operation by avoiding false readings and sensor malfunctions, thus maintaining cleaning efficacy.
Implementation Method 1
A level sensor is positioned within the bulk dispense tank. The level sensor includes a tether, a float body and a circuit board. The tether is mounted within the bulk dispense tank such that a distal end portion of the tether is movable relative to the bulk dispense tank. The float body is positioned at the distal end portion of the tether.
Implementation Method 2
The circuit board includes a gyroscope chip configured to measure movement of the float body on the tether.
Data Source
AI summary
A washing machine appliance includes a level sensor positioned within a bulk dispense tank. The level sensor includes a tether, a float body and a circuit board. The tether is mounted within the bulk dispense tank such that a distal end portion of the tether is moveable relative to the bulk dispense tank. The float body is positioned at the distal end portion of the tether. The circuit board is positioned within the float body and has one or more of an accelerometer chip and a gyroscope chip.