Washing Machine Spin Control for Unbalanced Load Detection
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Solution Overview
Problem
Washing machines experience undesirable vibrations due to unbalanced loads during the spin cycle, which existing technologies fail to effectively detect and prevent, leading to potential damage and inefficiency.
Innovation Solution
A method and apparatus that limit motor torque or power during the spin cycle's acceleration phase, monitoring the clothes basket's rotational speed to determine if it reaches predetermined speeds within a set time, thereby identifying and addressing out-of-balance conditions by limiting power or torque in specific RPM ranges to prevent unbalanced loads from spinning beyond desirable speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the motor applies maximum torque during spin cycle acceleration, then the spin cycle productivity is improved, but unbalanced loads cause excessive vibration and potential damage
Solution Approach 1:
The system performs preliminary detection during the acceleration phase by monitoring whether the basket reaches predetermined rotational speeds within expected timeframes. This early detection allows the system to identify unbalanced loads before they cause severe vibration or damage, enabling corrective action while the spin cycle is still in progress.
Solution Approach 2:
The control system continuously monitors rotational speed during acceleration and compares actual performance against expected parameters. When the basket fails to reach predetermined speeds within expected timeframes, the system detects this deviation as feedback indicating an unbalanced load, and automatically adjusts or terminates the spin cycle to prevent damage.
2Reliability
If existing detection technologies are used, then the system can identify unbalanced loads, but additional sensors and mechanical detectors increase device complexity
Solution Approach 1:
The system uses the motor's own operational characteristics during normal spin cycle acceleration as the detection mechanism. By monitoring whether the basket reaches predetermined rotational speeds within expected timeframes using existing control system components, the method enables unbalanced load detection without requiring separate sensors or mechanical detectors, thus avoiding increased device complexity.
Solution Approach 2:
The control system performs dual functions: it controls the motor during the spin cycle and simultaneously detects unbalanced loads. The same control circuitry and speed monitoring used for normal operation are leveraged to detect anomalies, eliminating the need for dedicated detection hardware and reducing overall system complexity.
Data Source
AI summary
An apparatus and techniques for detecting unbalanced load in a washing machine are provided. A clothes basket containing a load of clothing and rotatable about an axis is accelerated. As the clothes basket passes a first predetermined rotational speed, one of power and torque applied to the clothes basket is limited. It is determined whether the clothes basket accelerates from the first predetermined to a second predetermined rotational speed within a predetermined time. Failure to reach the second predetermined rotational speed within the predetermined time signifies an out-of-balance condition as to the load of clothing. No resonance of the machine lies between the first and second predetermined rotational speeds. In another aspect, a similar technique can be employed, with or without limiting power or torque, wherein a resonance does lie between the first and second predetermined rotational speeds.