Rotatable drum laundry machine and control method thereof
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Solution Overview
Problem
Existing washing machine unbalance control methods are inefficient in redistributing laundry load to reduce unbalance, as they rely on fixed redistribution speeds and complex motor control algorithms, leading to potential machine damage and uneven load distribution.
Innovation Solution
A control method that generates a sinusoidal motor speed profile based on estimated unbalance and inertia values, varying the amplitude to automatically redistribute laundry load and adjust motor speed to prevent uncontrolled movement and ensure precise balancing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a fixed high unbalance threshold (greater than 700g) is used to limit redistribution steps, then the time consumed for redistribution is reduced, but the precision of unbalance detection and redistribution effectiveness deteriorates
Solution Approach 1:
The patent applies dynamics by making the unbalance threshold adaptive rather than fixed. The control unit dynamically adjusts the threshold based on the measured unbalance values during different phases of the spin cycle. This allows the system to use a lower threshold initially for precise detection, then raise it later to limit redistribution steps, thereby resolving the contradiction between detection precision and time consumption.
2Ease of operation
If the drum rotational speed is sharply reduced to enable laundry redistribution, then laundry redistribution becomes possible, but laundry may move uncontrolledly causing increasing unbalance
Solution Approach 1:
The patent applies periodic action by implementing a two-phase speed control strategy. In the first phase, the drum rotates at a lower speed to enable laundry redistribution. In the second phase, the speed is increased to a higher value to stabilize the laundry and prevent uncontrolled movement. This periodic speed variation allows the system to achieve both redistribution capability and unbalance control stability.
3Device complexity
If a fixed redistribution speed is used based on prefixed laundry weight, then the control algorithm is simplified, but the method becomes inefficient for varying load weights
Solution Approach 1:
The patent applies parameter changes by making the redistribution speed adaptive based on the actual laundry load weight. The control unit determines the laundry weight and adjusts the redistribution speed accordingly. This allows the system to maintain optimal redistribution efficiency for varying load weights while keeping the control algorithm relatively simple through automated parameter adjustment.
4Manufacturing precision
If complex motor control algorithms are used to stiffen or relax motor control speed for unbalance-based oscillation, then laundry redistribution precision is improved, but device complexity increases
Solution Approach 1:
The patent applies feedback by using the measured unbalance values to automatically adjust the motor control speed. The control unit continuously monitors the unbalance and adjusts the redistribution speed accordingly, eliminating the need for complex stiffening or relaxing algorithms. This feedback mechanism achieves precise laundry redistribution while keeping the control system relatively simple.
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
The method effectively reduces unbalance by automatically adapting to the actual laundry load, preventing machine damage and ensuring precise redistribution without causing unwanted vibrations or walking issues, even with varying load weights.
Implementation Method 1
an electric motor to generate a drive force necessary to rotate the drum
Implementation Method 2
estimating an inertia value indicative of the inertia of the load in the laundry drum, varying the amplitude of said sinusoidal speed profile based on said estimated unbalance value and inertia value
Implementation Method 3
if the drum is rotated at a high speed while laundry is not uniformly distributed along the inner wall of the drum, i.e., the laundry is unbalanced, an eccentric force is applied to a rotary shaft of the drum
Data Source
AI summary
A method for redistributing a laundry load in a drum of a washing machine in order to reduce the unbalance generated to the nonuniform distribution of said laundry load in said drum. The method comprises: generating a sinusoidal motor speed profile (RS(t)), controlling the electric motor based on the sinusoidal motor speed profile (RS(t)), estimating unbalance value indicative of the unbalance of load in the laundry drum, estimating an inertia value indicative of the inertia of the load in the laundry drum, varying the amplitude of the sinusoidal speed profile (RS(t)) based on estimated unbalance value and inertia value, and controlling said electric motor based on modified sinusoidal motor speed profile.