Washer Drum Imbalance Detection for Extraction Speed Selection
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Solution Overview
Problem
Commercial front-loading washer/extractor-type laundry machines face load imbalance issues during water extraction, leading to severe mechanical stress and potential structural damage due to high centrifugal forces and uneven distribution of wet laundry.
Innovation Solution
A control system that detects load imbalance by monitoring the phase angle variation between voltage and current applied to the motor, characterizes the imbalance into predefined zones, and adjusts the rotation speed for extraction to prevent mechanical stress, optionally initiating load redistribution for better balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the drum is rotated at high speed for water extraction, then water removal efficiency is improved, but mechanical stress and structural damage risk increase due to load imbalance
Solution Approach 1:
The system performs a preliminary low-speed rotation phase before the high-speed extraction phase to detect and address load imbalance. During this preliminary phase, the drum rotates at a low speed to allow clothing to redistribute and achieve better balance, preventing severe vibrations and mechanical stress during subsequent high-speed extraction.
Solution Approach 2:
The system dynamically adjusts the extraction speed based on detected load imbalance conditions. The microprocessor monitors phase angle variations and automatically selects appropriate extraction speeds from predefined ranges, allowing the system to optimize between water removal efficiency and mechanical stress prevention in real-time.
2Productivity
If the drum is rotated at high speed for water extraction, then water removal efficiency is improved, but vibrations and mechanical stress increase due to load imbalance
Solution Approach 1:
The system performs a preliminary low-speed rotation phase before the high-speed extraction phase to detect and address load imbalance. During this preliminary phase, the drum rotates at a low speed to allow clothing to redistribute and achieve better balance, preventing severe vibrations and mechanical stress during subsequent high-speed extraction.
Solution Approach 2:
The system converts the harmful effect of load imbalance into useful information by monitoring phase angle variations. The detected phase angle data is used to characterize imbalance severity and automatically adjust extraction parameters, turning what would be a destructive condition into a control input for optimizing extraction while preventing damage.
3Measurement precision
If the phase angle monitoring method is used for load imbalance detection, then detection accuracy is improved, but control system complexity increases
Solution Approach 1:
The system replaces complex mechanical vibration sensors and balance detection mechanisms with an electrical measurement approach. By monitoring the phase angle between voltage and current in the motor drive system, the invention infers load imbalance conditions without requiring additional mechanical sensing equipment, thereby maintaining high detection accuracy while minimizing system complexity.
Solution Approach 2:
The system uses the motor's own electrical characteristics (voltage and current phase angle) to detect load imbalance conditions. This self-service approach eliminates the need for separate detection sensors or complex mechanical monitoring systems, as the motor's electrical signature naturally reveals imbalance information that can be processed by the existing microprocessor.
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
Effectively manages load imbalance by setting optimal rotation speeds for water extraction, reducing mechanical stress and preventing structural damage, while allowing for user intervention and flexible extraction speed selection.
Implementation Method 1
a drive controller for the motor that rotates the drum monitors the variation of a phase angle between the voltage and current applied to the motor
Implementation Method 2
the rotational speed of the drum during the water extraction phase can be quite high, and can generate a centrifugal force of 300 G or higher
Data Source
AI summary
A control system for a laundry washing machine with a horizontal wash drum detects load imbalance in the drum and selects a proper rotation speed for the drum in a water extraction operation. A drive controller for the motor turning the drum detects a phase angle variation in the drive voltage and drive current applied to the motor as an indication of the load imbalance in the drum, and determines whether the detected load imbalance falls in one of a plurality of pre-defined load-imbalance zones. The drive controller then provides a signal indicating the detected imbalance zone to a machine controller of the washing machine. The machine controller selects a proper rotation speed for the extraction operation based on the detected imbalance zone, or alternatively initiates a load-redistribution operation to reduce the load imbalance.