Magnetic Float Detergent Level Sensing in Washing Machines
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Solution Overview
Problem
Conventional washing machines face issues with accurately sensing the surface level of liquid detergent in the reservoir tank due to corrosion and reduced sensing ability caused by contact between the level sensor and liquid detergent, as well as scale accumulation, leading to potential detergent shortages and inaccurate warnings.
Innovation Solution
A liquid additive supply device with a buoyancy body and non-contact magnetic sensing system, where a buoyancy body with a magnetic field is used to detect the surface level of liquid additives, allowing the sensor to operate without direct contact and maintaining accuracy despite scale accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a level sensor is used to detect liquid detergent level in the reservoir tank, then the liquid detergent level can be sensed, but the sensor suffers from corrosion and scale accumulation that reduces sensing ability and accuracy
Solution Approach 1:
The patent introduces a magnetic field as an intermediary between the sensor and the liquid detergent. The level sensor detects the position of a magnetic float through magnetic field interaction rather than direct contact with the liquid detergent. This intermediary magnetic field transmission mechanism allows the sensor to accurately measure liquid level while avoiding corrosion and scale accumulation that would otherwise degrade sensor performance
Solution Approach 2:
The patent replaces the conventional direct-contact mechanical level sensing system with a magnetic field-based non-contact sensing system. Instead of using electrodes or mechanical floats that physically contact the liquid detergent, the system uses a magnetic float detected by a Hall effect sensor or similar magnetic sensor, substituting mechanical contact with magnetic field interaction to eliminate corrosion and scaling issues
2Ease of operation
If liquid detergent is stored in the reservoir tank, then detergent supply is enabled, but scale accumulation occurs on the level sensor electrode
Solution Approach 1:
The magnetic field acts as an intermediary that transmits level information from the float to the sensor without requiring the sensor to contact the liquid detergent. This eliminates the direct interaction between the sensor electrode and liquid detergent that causes scale accumulation, while maintaining the detergent supply function in the reservoir tank
Solution Approach 2:
The patent extracts the sensing function from the liquid detergent environment by using a magnetic float that moves with the liquid level but is detected by a non-contact sensor. The harmful interaction between the sensor and liquid detergent is removed, allowing the detergent to be stored and supplied without causing scale accumulation on the sensing components
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 enables reliable and accurate detection of liquid additive levels, preventing degradation in sensing ability and ensuring timely notifications of shortages, even after prolonged use.
Implementation Method 1
a buoyancy body installed in the reservoir tank so that the vertical position of the buoyancy body varies with the surface level of the liquid additive
Implementation Method 2
a sensor unit installed at one side of the reservoir tank in a position facing the buoyancy body and configured to sense its distance from the buoyancy body
Data Source
AI summary
A washing machine with a liquid additive supply device capable of sensing an amount of liquid additive contained therein. A buoyancy body and a sensing unit are disposed in a reservoir tank of the liquid additive supply device. The vertical position and therefore the distance between the buoyancy body and a sensing unit vary with the surface level of liquid additive in the reservoir tank due to buoyancy effect. The buoyancy body may include a magnetic body and the sensing unit can detect the intensity of the magnetic body. The surface level of the liquid additive is too low, the sensing unit can generate a signal indicative of liquid additive shortage.