Washing Drum Imbalance Prediction Using Tub Deflection Signals
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Solution Overview
Problem
Current methods for predicting imbalances in washing machine drums during spin cycles are inadequate, as they often rely on estimating imbalances based on motor speed and laundry load, which can change due to water being spun out and mass distribution changes, leading to continuous fluctuations and potential mechanical stress.
Innovation Solution
A method and device that predict imbalances by characterizing the movement behavior of the washing machine's oscillating system through measured and controlled variables, such as the average amplitude of the tub's deflection, allowing for early and reliable imbalance forecasting, especially at lower speeds, and correcting for dewatering effects to optimize spin processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If imbalance is estimated using motor speed and laundry load, then prediction can be made early in the spin cycle, but the prediction accuracy deteriorates due to continuous changes from water being spun out and mass distribution changes
Solution Approach 1:
The patent performs preliminary imbalance prediction during the laundry distribution operation at lower speeds before the spin cycle begins. By characterizing the movement behavior of the oscillating system early when mass distribution is more stable, the system establishes a baseline prediction that can be adjusted during the spin cycle, rather than waiting until higher speeds where water extraction causes continuous changes.
Solution Approach 2:
The system continuously monitors the movement behavior of the oscillating system during the spin cycle and uses this feedback to adjust the imbalance prediction. By comparing actual measured values with predicted values, the system can correct for changes caused by water being spun out and mass distribution changes, maintaining prediction accuracy throughout the cycle.
2Productivity
If spin cycle starts immediately after laundry distribution, then productivity is improved, but mechanical stress increases due to uncorrected imbalances
Solution Approach 1:
The patent performs preliminary imbalance characterization during the laundry distribution operation before the spin cycle begins. This allows the system to identify potential imbalance issues in advance and take corrective actions, such as adjusting the spin cycle parameters or redistributing laundry, before the high-speed spin operation starts, thereby preventing mechanical stress while maintaining productivity.
Solution Approach 2:
The system takes preliminary counter-actions to offset potential harmful effects of imbalance before the spin cycle begins. By characterizing the oscillating system's movement behavior early and predicting imbalances, the system can apply counterbalancing measures or adjust operational parameters to prevent excessive mechanical stress during the spin cycle.
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
Enables accurate prediction and correction of imbalances before the spin cycle, reducing mechanical stress and saving time by allowing for improved speed regulation and optimal spin process management.
Implementation Method 1
a movement behavior of an oscillating system of the household appliance is characterized by the measured and/or controlled variable
Implementation Method 2
a path signal which characterizes a deflection of a tub of the household appliance from a rest position
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a method for predicting an unbalance (E800p) which occurs in a drum (2) of a domestic appliance for caring for laundry items (7) and is brought about by a distribution of the laundry items (7) in an interior of the drum (2), in which method the prediction is carried out in a lower value range of a rotational speed (n), in particular in a laundry distribution mode, and a value and/or a profile of the unbalance (E800p) is determined for an upper value range of the rotational speed (n = 800 rpm), in particular for a spin mode, wherein the unbalance (E800p) is predicted as a function of a measured variable and/or control variable (W), wherein a movement behaviour of an oscillating system of the domestic appliance is characterized by the measured variable and/or control variable (W).