Washing Machine Spinning Speed Control Using Motor Current Feedback
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Solution Overview
Problem
Existing washing machine methods for spinning or dry-spinning laundry after washing are inefficient, consuming excessive time and energy due to prolonged processes that do not account for the actual water content in the laundry, leading to unnecessary limitations on rotational speed to avoid vibrations.
Innovation Solution
A method that monitors the motor current to detect changes in laundry weight during spinning, adjusting rotational speed in incremental steps based on the motor current envelope and its derivative, optimizing the spinning process by increasing speed when water loss is minimal, and using projections inside the drum to enhance mixing and force distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional washing machines use fixed rotational speeds for spinning, then the structure is simple, but water removal efficiency is poor and drying time is prolonged
Solution Approach 1:
The patent implements dynamic speed adjustment during the spinning cycle based on real-time motor current monitoring. The control unit continuously monitors motor current and adjusts rotational speed in multiple stages (first spinning speed, second spinning speed, third spinning speed) according to detected laundry characteristics and water removal progress, transforming the fixed-speed system into an adaptive dynamic system that optimizes water removal efficiency.
Solution Approach 2:
The patent employs feedback control by monitoring motor current characteristics during spinning and using this information to adjust rotational speed. The control unit detects changes in motor current that indicate water removal progress and laundry characteristics, then feeds this information back to adjust the spinning speed accordingly, creating a closed-loop control system that improves water removal efficiency.
2Productivity
If rotational speed is continuously increased to improve water removal, then water removal efficiency improves, but energy consumption increases
Solution Approach 1:
The patent uses dynamic speed adjustment to match rotational speed with actual water removal needs. Instead of maintaining high speed throughout, the system adjusts speed in stages based on monitoring data, using higher speeds only when necessary to remove remaining water after initial water is expelled at lower speeds, thereby reducing overall energy consumption while maintaining water removal efficiency.
Solution Approach 2:
The patent changes operational parameters (rotational speed) based on process stage and detected conditions. The system transitions through different speed parameters (first, second, third spinning speeds) as the water removal process progresses, optimizing energy efficiency by using appropriate speed levels for each stage of water removal rather than maintaining maximum speed throughout.
3Productivity
If high rotational speeds are used from the beginning, then water removal is faster, but laundry distribution becomes uneven and mechanical stress increases
Solution Approach 1:
The patent applies preliminary action by using a first spinning speed at a lower level before progressing to higher speeds. This initial lower-speed phase allows laundry to be evenly distributed and settled in the drum before high-speed water removal begins, preventing mechanical stress and uneven distribution that would occur if high speeds were applied immediately to wet laundry.
Solution Approach 2:
The patent implements a dynamic speed progression that adapts to laundry condition changes. The system transitions from lower to higher speeds as laundry becomes drier and more stable, allowing gradual adaptation to mechanical stress and maintaining uniform distribution while progressively improving water removal efficiency.
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 significantly reduces the time and energy consumption required for dry-spinning laundry by dynamically adjusting rotational speed based on real-time water loss detection, ensuring efficient water removal without causing vibrations.
Implementation Method 1
The spinning of the laundry is performed at different and in particular increasing rotational speeds
Implementation Method 2
a drive control for the drive motor, which controls and supplies power to the drive motor... the drive control monitors the motor current and records the variation over time of this motor current
Data Source
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AI summary
A washing machine (11) comprises a rotatable drum (15) for receiving laundry, a drive motor (19) for the drum, a drive control for the drive motor and a washing machine control (24), the washing machine control being connected to the drive control. In a method of operating the washing machine for dry-spinning laundry at different and increasing speeds, wherein a certain speed is kept constant for a certain time in the manner of speed steps, the drum is at first rotated at a certain constant speed for spinning the laundry. The drive control monitors the motor current and records the variation over time of the motor current as well as an envelope curve (E) of the motor current and an average of this envelope. The envelope of the motor current or its average is derived once after the time. As soon as the first derivative of the envelope or the average falls below a certain predetermined threshold value (V) or becomes zero, the condition is defined that the spun laundry in the drum no longer loses any or sufficient water. Then the rotational speed of the drum is increased to a higher rotational speed, until the first derivative again falls below a certain predetermined threshold value or becomes zero.