Washer Drum Spin Control for Load Imbalance Redistribution
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Solution Overview
Problem
Laundry treating appliances experience undesirable vibrations and movements due to load imbalances during spin cycles, as laundry does not distribute evenly in the drum, leading to centrifugal forces that cause items to be 'satellized' against the drum wall rather than tumbling, resulting in operational imbalances.
Innovation Solution
A method and apparatus that reduce the rotational speed of the treating chamber when an imbalance is detected, allowing for redistribution of the laundry load without stopping rotation, and then increase speed back to spin speed once the imbalance is sufficiently reduced, using motor torque analysis in the frequency domain to monitor and manage the imbalance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the drum is rotated at high spin speeds to extract liquid from the laundry load, then liquid extraction efficiency is improved, but load imbalance causes undesirable vibrations and movements
Solution Approach 1:
The system implements periodic speed reductions during the spin cycle to allow laundry redistribution. The controller periodically reduces drum speed from high spin speed to a lower speed, allowing the laundry load to redistribute and reduce imbalance, then increases speed back to spin speed. This periodic action continues until imbalance is reduced to an acceptable level, eliminating vibrations while maintaining extraction efficiency.
2Stability of the object's composition
If the rotational speed is reduced to redistribute the laundry load, then load balance is improved, but extraction efficiency decreases
Solution Approach 1:
The system dynamically adjusts drum speed based on real-time imbalance detection. Rather than maintaining a fixed speed, the controller continuously monitors vibration levels and motor current, reducing speed only when imbalance is detected and increasing speed when balance is achieved. This dynamic adjustment allows the system to maintain high extraction efficiency while minimizing the time spent at reduced speeds for redistribution.
Solution Approach 2:
The system performs preliminary redistribution actions by reducing speed before the imbalance becomes severe. By detecting early signs of imbalance through vibration sensors and motor current analysis, the controller proactively reduces speed to prevent excessive vibration buildup, then quickly restores spin speed to maintain extraction efficiency.
3Stability of the object's composition
If the drum rotation is completely stopped to redistribute laundry, then load balance is maximized, but cycle time increases and energy consumption increases
Solution Approach 1:
Instead of completely stopping the drum, the system applies partial action by reducing speed to a low but non-zero rotational speed. This partial speed reduction is sufficient to allow laundry redistribution and imbalance correction while maintaining minimal centrifugal force to keep clothes pressed against the drum wall. The drum continues rotating slowly rather than stopping completely, significantly reducing redistribution time and allowing immediate resumption of high-speed spinning once balance is achieved.
4Stability of the object's composition
If the drum rotation is completely stopped to redistribute laundry, then load balance is maximized, but energy consumption increases
Solution Approach 1:
The system uses partial action by maintaining minimal rotation during redistribution rather than complete stoppage. This allows the laundry to redistribute under reduced centrifugal force while the drum continues to rotate slowly, eliminating the need for complete stoppage and restart. The energy savings from avoiding complete stoppage and motor restart are significant, while still achieving effective load redistribution.
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 efficiently redistributes the laundry load, reduces energy consumption by avoiding complete stoppages, and shortens cycle times by allowing the process to continue immediately upon imbalance elimination, minimizing the formation of new imbalances and maintaining operational stability.
Implementation Method 1
monitoring the magnitude of the imbalance during the reduction of the rotational speed
Implementation Method 2
the drum is rotated at speeds high enough to impart a centrifugal force on the load great enough to hold (a/k/a 'plaster' or 'satellize') the load to the peripheral wall of the drum
Data Source
AI summary
An apparatus and method for detecting an imbalance in the laundry load and effecting a redistribution of the imbalance by reducing the rotational speed of the treating chamber such that part of the load may redistribute while part of the load remains satellized, without ceasing rotation, and increasing the rotational speed back to a spin speed after redistribution.