Laundry Drying Switch-Off Control Using Voltage-Energy Feedback
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Solution Overview
Problem
Existing methods for determining the switch-off time of a care process in domestic appliances, such as tumble dryers, suffer from inaccuracies due to signal deterioration when transitioning from large to small contact area electrodes, leading to high scatter in final moisture content measurements.
Innovation Solution
A method that determines the switch-off time by calculating the sum of total heating energy and instantaneous voltage drop across laundry items, using a processor unit to assess when a predefined voltage-energy cluster is reached, ensuring precise termination of the care process when a specified final moisture content is achieved, thereby optimizing energy usage and ensuring consistent drying results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If end shield electrodes with smaller contact area are used, then the device complexity is reduced, but the measurement precision deteriorates due to signal deterioration and high scatter in final moisture content
Solution Approach 1:
The patent combines multiple measurement parameters (voltage drop, total heating energy, and their derivative relationships) into a unified evaluation system. By merging these parameters and analyzing their interrelationships, the system achieves accurate moisture content determination despite using simplified end shield electrodes with smaller contact area.
2Device complexity
If the care process continues until a fixed time or energy threshold, then the device complexity is reduced, but the loss of energy increases due to unnecessary continued operation after moisture content is reached
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors the relationship between voltage drop and total heating energy during the care process. When the derivative relationship between these parameters indicates that the final moisture content has been reached, the system provides feedback to terminate the heating process, thereby avoiding unnecessary energy consumption while maintaining precise control.
3Loss of time
If the care process is terminated early based on simple time thresholds, then the loss of time is reduced, but the manufacturing precision deteriorates as the laundry may not reach the specified final moisture content
Solution Approach 1:
The patent performs preliminary analysis of the relationship between voltage drop and total heating energy during the care process. By evaluating the derivative relationship between these parameters in advance, the system can predict when the final moisture content will be reached and terminate the process at the optimal moment, ensuring both time efficiency and consistent moisture content results.
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 approach allows for precise determination of the switch-off time, ensuring the laundry reaches the desired moisture content while minimizing unnecessary energy consumption and ensuring consistent drying performance across varying loads and conditions.
Implementation Method 1
the residual moisture content of the laundry items is determined by measuring an electrical resistance of the laundry items
Implementation Method 2
an electrical voltage dropping through an electric current of a predetermined strength across an electrical resistance of the items of laundry is determined
Data Source
AI summary
The invention relates to a method for determining a switch-off moment of a care process for treating items of laundry introduced into a household appliance. A course of a total heat energy (E) for the care of the items of laundry is defined and an electrical voltage dropping against an electrical resistance of the items of laundry is determined during the care process, and the switch-off moment is determined according to the course of the total heat energy (E) during the care process, a total of the pre-defined total heat energy (ETarget) and the actual value of the electrical voltage (Uw) of the items of laundry. The duration (t) of the process can be taken into account instead of the total heat energy (E).