Laundry washing machine and control method thereof
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Solution Overview
Problem
Laundry washing machines face challenges in accurately controlling water temperature during the initial wetting phase and subsequent phases due to the temperature sensor not being submerged in water, leading to potential damage to delicate items and prolonged correction times.
Innovation Solution
A method that determines the immersion status of the temperature sensor and performs different control procedures to accurately control the hot and cold water valves, ensuring reliable temperature management by adjusting the water supply based on the sensor's immersion status and selected washing program parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the temperature sensor is arranged at a prefixed height above the bottom surface of the washing tub, then the sensor is protected from damage and easier to install, but the sensor cannot provide correct temperature control during the initial wetting phase when water level is low
Solution Approach 1:
The control device determines the water level and sensor immersion status in advance before initiating full water supply. By checking whether the sensor is submerged and predicting the wetting phase timing, the system prepares appropriate control strategies proactively, avoiding temperature control errors during the critical initial filling period
Solution Approach 2:
The control device continuously monitors the sensor immersion status and uses this feedback to dynamically adjust valve control strategies. When the sensor is not submerged, the system activates alternative control logic that accounts for the lack of accurate temperature data, thereby maintaining reliable temperature control throughout all washing phases
2Measurement precision
If the temperature sensor is not submerged in water, then the sensor remains dry and protected, but the control device cannot accurately determine water temperature leading to wrong valve control
Solution Approach 1:
The control device applies preliminary protective actions by detecting when the sensor is not submerged and anticipating potential temperature control errors. It activates preventive control strategies during the wetting phase to avoid supplying excessively hot water that could damage delicate laundry, addressing the problem before it occurs
Solution Approach 2:
The control device introduces an intermediary decision-making layer that interprets sensor immersion status and translates it into appropriate valve control actions. This intermediary logic layer bridges the gap between the dry sensor condition and safe water supply control, preventing harmful effects on laundry
3Productivity
If hot water is supplied during the wetting phase without accurate temperature sensing, then the washing process can proceed faster, but delicate laundry may be damaged by hot water
Solution Approach 1:
The valve control strategy dynamically adapts based on sensor immersion status and washing phase timing. During the wetting phase when the sensor is not submerged, the system applies restricted control logic that limits hot water supply, while transitioning to normal dynamic control once the sensor is submerged, thereby balancing speed and safety throughout the washing process
Data Source
AI summary
A laundry treatment machine (1) has an outer casing (2), and a washing tub (3) which is arranged inside the outer casing (2). A rotatable washing drum (4) is arranged in axially rotating manner inside the washing tub (3) and is structured to receive the laundry to be treated. A liquid supplying system is provided for supplying hot liquid and/or cold liquid into the washing tub (3). A temperature sensor (22) is arranged in the washing tub (3) and is designed for sensing the temperature of the liquid contained in the washing tub (3). An electronic control device (23) is configured to: determine whether the temperature sensor (22) is immersed in liquid; and perform a first or a second control procedure, different from one another, to control the water supplying system based on a determined immersion status of the temperature sensor (22).