Drum Washing Machine Ball Balancer Control for Tub Oscillation
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Solution Overview
Problem
Existing drum-type washing machines with ball balancers face increased manufacturing costs and imperfect prevention of tub oscillations greater than a predetermined level due to the use of multiple races with different ball sizes and viscosities, which are not calculated precisely to prevent excessive oscillations.
Innovation Solution
A method that maintains the drum's rotational speed at a sustained level until the oscillation frequency reaches a lowest value, then adjusts the ball position to prevent tub oscillations exceeding a predetermined level, allowing the use of a single race with varying ball sizes and viscosities to reduce costs and effectively control oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If at least two races with different ball sizes and viscosities are used to prevent resonant oscillation, then tub oscillation is reduced, but manufacturing cost increases
Solution Approach 1:
The patent merges the functions of multiple races with different ball sizes and viscosities into a single race. The controller coordinates the operation of multiple ball balancers (first and second ball balancers) within one race to achieve the oscillation prevention effect that previously required multiple races, thereby simplifying manufacturing while maintaining performance.
Solution Approach 2:
The patent changes the control parameters by introducing coordinated control of multiple ball balancers with different viscosities within a single race. The controller adjusts the operation timing and parameters of each ball balancer to compensate for laundry imbalance and prevent tub oscillation, replacing the structural parameter change (multiple races) with a control parameter change.
2Reliability
If multiple races are used to reduce oscillation occurrence probability, then tub oscillation is better controlled, but device complexity increases
Solution Approach 1:
The patent combines multiple ball balancer mechanisms into a single race structure. The first and second ball balancers operate within one race, coordinated by a controller, achieving reliable oscillation control without the structural complexity of multiple races. This reduces device complexity while maintaining or improving reliability through coordinated control.
Solution Approach 2:
The patent implements feedback control where the controller monitors the operation status of multiple ball balancers and adjusts their coordination to prevent tub oscillation. This feedback mechanism ensures reliable oscillation control by dynamically adjusting the ball balancer operations based on detected conditions, replacing the need for multiple races with intelligent control.
3Stability of the object's composition
If ball balancer is used to compensate for uneven laundry distribution, then balance is maintained, but resonant oscillation occurs at specific rpm range
Solution Approach 1:
The patent applies preliminary action by having the first and second ball balancers operate in coordination before resonant oscillation can occur. The controller pre-coordinates the ball balancer operations to compensate for potential imbalance issues, preventing the differential rotational speed between drum and balls from causing resonant oscillation in the 205-300 rpm range.
Solution Approach 2:
The patent employs periodic action through the coordinated operation of multiple ball balancers that move with phase differences. This periodic coordination of ball movements compensates for uneven laundry distribution while preventing resonant oscillation, maintaining balance stability without the harmful oscillations that occur with single ball balancer systems.
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 effectively prevents tub oscillations greater than the predetermined level by precise calculation, reducing manufacturing costs and ensuring stable operation, while maintaining the washing machine's balance without excessive oscillation.
Implementation Method 1
balls of the ball balancer move in a predetermined direction due to a differential centrifugal force caused by the unbalanced rotation
Implementation Method 2
balls provided in at least two races move with a phase difference to compensate for the imbalance caused by the uneven distribution of laundry and balls
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A method controls tub oscillation in a drum type washing machine by utilizing a ball balancer. The method includes maintaining an rpm of a drum in a predetermined rpm level for a predetermine period of time during a dehydration operation, thereby reducing a differential rotation speed between the drum and a ball, and re-increasing the rpm, such that the tub is not subject to the oscillation that is greater than a predetermined level. The drum type washing machine adopts a single race having different ball sizes and viscosities, so that the manufacturing cost of the washing machine is reduced. The tub is prevented from being subject to oscillation greater than a predetermined level through precise calculation.