Washing Tub Temperature Control When the Sensor Is Not Submerged
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Solution Overview
Problem
Laundry washing machines face challenges in accurately controlling water temperature due to the temporary immersion status of temperature sensors, leading to incorrect water temperature supply, potentially damaging delicate items and requiring longer correction times.
Innovation Solution
Implementing a control method that determines the immersion status of the temperature sensor to perform different control procedures for the water supply system, ensuring reliable control of hot and cold water valves based on immersion status, user-selected programs, and sensed temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the temperature sensor is arranged at a prefixed height above the bottom surface of the washing tub, then the device structure is simplified and easier to manufacture, but the temperature measurement accuracy deteriorates when the sensor is not submerged in water
Solution Approach 1:
The control device dynamically selects between two different control procedures based on the immersion status of the temperature sensor. When the sensor is submerged, standard temperature-based control is used. When not submerged, an alternative control procedure is activated that relies on pre-stored temperature values corresponding to different water levels, ensuring accurate temperature control regardless of sensor position.
Solution Approach 2:
The system changes the control parameter from direct sensor measurement to pre-stored temperature values when the sensor is not submerged. The control device stores multiple temperature values in memory that correspond to different water levels, and selects the appropriate stored value based on the current water level detection, effectively changing how temperature information is obtained.
2Ease of operation
If the temperature sensor is not submerged in water during initial filling, then the device can operate with simpler water level management, but the temperature control reliability deteriorates causing wrong water temperature supply
Solution Approach 1:
The control device performs preliminary detection of the temperature sensor's immersion status before initiating the main temperature control process. Based on this preliminary detection, it pre-selects the appropriate control procedure (standard sensor-based control or alternative stored-value control), ensuring reliable temperature control from the beginning of the washing cycle without requiring complex real-time adjustments.
Solution Approach 2:
The system implements feedback by continuously monitoring the water level and comparing it with the temperature sensor position. When the water level rises to submerge the sensor, the system transitions from alternative control mode to standard sensor-based control mode, ensuring continuous reliable temperature control throughout the filling process.
3Device complexity
If standard temperature control is used when the sensor is not immersed, then the control system remains simple, but the time required to correct temperature deviations increases beyond available program time
Solution Approach 1:
The control device performs preliminary detection of the temperature sensor's immersion status before initiating the main temperature control process. Based on this preliminary detection, it pre-selects the appropriate control procedure, ensuring immediate correct temperature control from the start of water filling, eliminating the need for time-consuming corrections later in the washing program.
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 method prevents damage to delicate items by accurately controlling water temperature, even when the sensor is not submerged, and reduces the time required to correct temperature deviations during washing cycles.
Implementation Method 1
a temperature sensor which is arranged into the washing tub and is designed for sensing the temperature of the liquid contained in said washing tub
Implementation Method 2
a water supplying system provided with two valves for supplying hot water and cold water into the washing tub
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Laundry treatment machine (1) comprising an outer casing (2), a washing tub (3) which is arranged inside the outer casing (2), a rotatable washing drum (4), which 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 for supplying hot liquid and/or cold liquid into said washing tub (3), a temperature sensor (22) which is arranged into 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) configured to: determine whether the temperature sensor (22) is immersed into liquid; perform a first or a second control procedure, different one another, to control the water supplying system based on a determined immersion status of the temperature sensor (22).