Laundry treatment appliance
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Solution Overview
Problem
Existing solutions for monitoring the load of Permanent Split Capacitor Motors (PSCM) in laundry treatment appliances, which rotate in both directions, are inefficient and complex, failing to effectively prevent locked rotor conditions and motor damage due to excessive load.
Innovation Solution
A laundry treatment appliance with a control unit that assesses overload conditions by sensing voltages at specific terminals and using TRIACs to manage motor direction, allowing for efficient detection and prevention of overload by quantifying torque and load based on voltage amplitude and RMS calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal protection systems with dedicated temperature sensors are used to prevent motor damage, then motor reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses voltage sensing at motor terminals as an intermediary method to indirectly monitor motor load conditions. Instead of directly measuring temperature with dedicated sensors, the system senses voltage amplitude and RMS values at the motor terminals, which correlate with load and thermal stress conditions. This intermediary approach provides protection while avoiding complex temperature sensing hardware.
Solution Approach 2:
The patent replaces the thermal protection system with an electrical monitoring approach. By substituting dedicated temperature sensors and thermal protection circuits with voltage sensing and computational analysis of voltage amplitude and RMS values, the system achieves motor protection functionality through electrical measurements and digital processing rather than thermal sensing hardware.
2Measurement precision
If voltage sensing and computational methods are used to assess motor load, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The control unit leverages existing voltage sensing infrastructure and computational resources already present in the washing machine control system. The method uses standard voltage measurement capabilities and basic computational operations (amplitude detection, RMS calculation) that the control unit can perform using its existing processors and sensors, rather than requiring dedicated specialized hardware for load measurement.
Solution Approach 2:
The patent transforms the physical quantity of interest (motor load) into measurable electrical parameters (voltage amplitude, voltage RMS values) that can be sensed and processed. By changing the measurement approach from direct mechanical or thermal load sensing to electrical parameter analysis, the system achieves precise load assessment using standard electrical measurement techniques and computational methods.
Data Source
Figure 1
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Figure 3A~3B
AI summary
A laundry treatment appliance (100) is provided. The laundry treatment appliance (100) comprises a cabinet (110) and a drum (107) rotatably accommodated within said cabinet for housing laundry to be treated. The laundry treatment appliance (100) further comprises a permanent split capacitor motor (160) selectively operable to rotate the drum clockwise and counterclockwise. The permanent split capacitor motor is configured to be supplied by a supply voltage provided across a first supply terminal (250) and a second supply terminal (255) of an AC power supply. The permanent split capacitor motor comprises a main terminal (235), a first control terminal (240), and a second control terminal (245). The main terminal is coupled with the first supply terminal. The laundry treatment appliance (100) further comprises a switching apparatus (262, 264, 266, 268) configured to selectively couple: - the first control terminal with the second supply terminal, while decoupling the second control terminal from the second supply terminal, for rotating the drum clockwise, or - the second control terminal with the second supply terminal, while decoupling the first control terminal from the second supply terminal, for rotating the drum counterclockwise. The laundry treatment appliance (100) further comprises a voltage sensing unit (270, 272) configured to sense the voltage at the first control terminal to produce a corresponding first sensed voltage and to sense the voltage at the second control terminal to produce a corresponding second sensed voltage. The laundry treatment appliance (100) further comprises a control unit (280) configured to assess an overload condition of the drum based on: a) the first sensed voltage when the second control terminal is coupled with the second supply terminal, and b) the second sensed voltage when the first control terminal is coupled with the second supply terminal.