Washing Machine Freeze Detection Using Water Level Variation
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Solution Overview
Problem
Existing washing machines face issues with accurately determining whether water drainage ports are frozen, leading to potential overheating and fire risks due to misjudgment by temperature sensors, especially when the washing machine is installed at an angle or when residual water is present.
Innovation Solution
A washing machine system that includes a tub, a drum, a driving unit, a water level sensor, and a control unit to determine freeze or non-freeze conditions based on water level variation during drum rotation, eliminating the need for temperature sensors and ensuring accurate detection regardless of installation position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a temperature sensor is disposed adjacent to a heater to determine freeze or non-freeze, then the freeze protection operation can be implemented, but the temperature sensor may completely sink under water when the washing machine is installed inclined or when residual water exists, causing misjudgment and potential overheating
Solution Approach 1:
The patent removes the temperature sensor from the system and replaces it with a water level sensor. This extraction eliminates the problem of temperature sensor misplacement and submersion, as the water level sensor is positioned to detect water levels in the tub without being affected by inclination or residual water conditions.
Solution Approach 2:
The water level sensor serves multiple functions: it detects both the presence of water and the freeze state indirectly through water level variation during drum rotation. This multi-functionality replaces the specialized temperature sensor while providing more reliable operation across different installation conditions.
2Adaptability or versatility
If the washing machine is installed at an angle with respect to the ground, then installation flexibility is improved, but the temperature sensor may not accurately sense the water temperature due to its position relative to the water level
Solution Approach 1:
The patent replaces the thermal sensing mechanism (temperature sensor) with a mechanical/water-based sensing mechanism (water level sensor). The water level sensor detects freeze conditions through water level changes during drum rotation, which are independent of the washing machine's installation angle, thus maintaining measurement accuracy across different installation configurations.
3Reliability
If a heater is operated based on temperature sensor readings, then freeze protection is provided, but a part of the heater may not sink under water and become overheated causing fire risk
Solution Approach 1:
The system uses feedback from the water level sensor to control heater operation. By detecting water level variations during drum rotation, the control unit accurately determines freeze conditions and activates the heater only when necessary and when water is present, preventing both freeze damage and overheating hazards.
Solution Approach 2:
The water level sensor acts as an intermediary between the drum rotation and the heater control. It indirectly detects freeze conditions through water level changes, providing safe and accurate information for heater operation without the risks associated with direct temperature sensing in inclined or partially-filled conditions.
Data Source
AI summary
Provided are a washing machine and a method for controlling the same. The method for controlling a washing machine includes supplying water to a tub, driving a driving unit to perform tumbling to rotate a drum disposed in the tub, calculating a water level variation in the tub, and displaying freeze state information on a display unit when the calculated water level variation is less than a reference water level variation.