Washing Drum Unbalance Sensing Using Torque and Speed Signals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing laundry washing machines fail to effectively detect and address dynamic unbalance in the wash drum assembly, leading to potential collisions, severe vibrations, and mechanical stress due to their inability to measure the dynamic unbalance component, which is masked by weak fluctuations in speed or torque.
Innovation Solution
A method and device for sensing the motion of the wash assembly due to dynamic unbalance, utilizing an electronic control system that measures torque and rotation speed to detect the quasi-static and second-harmonic components of dynamic unbalance, preventing excessive spin speeds by redistributing laundry when thresholds are exceeded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If known control devices determine unbalance solely on the basis of static unbalance using speed or torque fluctuations, then the device complexity remains low, but the measurement precision is insufficient to detect dynamic unbalance
Solution Approach 1:
The patent introduces an intermediary computational parameter (derived from torque and speed measurements) that acts as a mediator to detect dynamic unbalance. Instead of directly measuring dynamic unbalance components, the system uses the relationship between torque fluctuations and speed variations as an intermediary indicator, allowing detection of dynamic unbalance effects without requiring direct sensors for each component.
Solution Approach 2:
The patent replaces direct mechanical measurement of dynamic unbalance components with an electronic control system that computes unbalance effects from torque and speed data. This substitution of mechanical measurement systems with electronic computation enables detection of dynamic unbalance while maintaining relatively simple device architecture.
2Productivity
If the spin stage is activated without detecting dynamic unbalance, then the productivity is high, but the reliability decreases due to potential collisions and mechanical stress
Solution Approach 1:
The patent applies preliminary action by detecting and evaluating dynamic unbalance parameters before authorizing the spin stage to activate. The control device computes dynamic unbalance indicators during the acceleration phase and determines whether conditions are safe for high-speed spinning, preventing potential damage before it occurs rather than reacting to problems after they arise.
Solution Approach 2:
The system implements feedback by continuously monitoring torque and speed during acceleration, computing dynamic unbalance parameters, and using this information to control whether the spin stage should proceed. The feedback loop evaluates unbalance conditions and adjusts the operational authorization accordingly, ensuring reliability while maintaining productivity when conditions permit.
Data Source
AI summary
A method of sensing the motion of the wash assembly (3) of a washing machine (1) due to the dynamic unbalance of the laundry drum assembly (6), and which comprises the steps of: increasing the rotation speed (ω) of a laundry drum (6) to a first rotation speed (ωDIST); determining a first parameter (TFRICTION; AHFREF) related to the time pattern of the values of an unbalance function A=T−Jdω/dt; increasing the rotation speed (ω) of the laundry drum (6) by a predetermined value (Δω) determining, at each increase (Δω) in rotation speed (ω), a second parameter (ALF; AHF) related to the time pattern of the values of the unbalance function A=T−Jdω/dt filtered at the predetermined filtration frequency (LF; HF); calculating the difference (TdynLF; TdynHF) between the second parameter (ALF; AHF) and the first parameter (TFRICTION; AHFREF).