Washer Drum Inertia Estimation for Sensorless Water Extraction
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Solution Overview
Problem
Existing laundry treating appliances face challenges in optimizing water extraction cycles without sensors, which affects efficiency and cost-effectiveness.
Innovation Solution
A method and system that estimate water mass extraction in laundry treating appliances by accelerating the drum to distinct speeds using acceleration ramps, determining torque, acceleration, and angular position to estimate inertia values, and transforming these values based on changing laundry load geometries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors are used to monitor water extraction, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces physical sensors with a parameter estimation algorithm that uses existing motor control data (torque, speed, acceleration) to infer water mass extraction. The controller estimates inertia values by analyzing motor torque requirements during drum rotation, eliminating the need for additional sensors while maintaining measurement capability
Solution Approach 2:
The system uses its own operational parameters (motor torque, drum speed, acceleration) to self-diagnose and monitor water extraction. The controller leverages data already being collected for motor control to derive inertia estimates, making the system self-monitoring without external sensors
2Productivity
If drum rotation speed is increased for water extraction, then productivity is improved, but use of energy increases
Solution Approach 1:
The system dynamically adjusts drum rotation speed based on real-time inertia estimates. When the laundry load is heavy and wet (high inertia), the controller increases rotation speed to maintain effective water extraction. When the load becomes lighter and drier (lower inertia), the controller reduces speed, optimizing energy consumption while maintaining extraction efficiency
Solution Approach 2:
The parameter estimation algorithm provides continuous feedback on water mass extraction by monitoring changes in inertia values. This feedback loop allows the controller to adjust motor power and rotation speed in real-time, increasing speed when extraction is needed and reducing speed when the load is sufficiently dry, thereby optimizing energy usage
3Measurement precision
If inertia estimation is performed at multiple dwell times, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The system performs continuous parameter estimation during the spin cycle by analyzing motor torque and speed data at multiple dwell times without pausing the extraction process. The controller estimates inertia values at different rotation speeds throughout the cycle, maintaining continuous monitoring while the drum keeps rotating and extracting water
Solution Approach 2:
The controller periodically samples inertia data at predetermined dwell times during the spin cycle (e.g., at 100 RPM, 200 RPM, 400 RPM). These periodic measurements are integrated into the continuous extraction process, providing accurate inertia estimation at key intervals without stopping the drum or extending cycle duration
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
This approach allows for efficient water extraction monitoring and optimization of washing machine cycles without the need for sensors, reducing costs while improving performance and energy efficiency.
Implementation Method 1
accelerating rotation of the drum during a water extraction cycle to at least two distinct speeds
Implementation Method 2
estimating with a parameter estimator inertia values of a laundry load in the drum, based on the torque, acceleration, speed, and/or angular position of the drum
Data Source
AI summary
A method of estimating water mass extraction in a laundry treating appliance where the geometry changes in a laundry load affect inertia estimations includes accelerating rotation of the drum during a water extraction cycle to at least two distinct speeds, each for a dwell time, by way of acceleration ramps; determining, during the accelerating rotation, by a controller communicably coupled with the motor, a torque of the motor, an acceleration of the drum, a speed of the drum, and/or an angular position of the drum; and estimating with a parameter estimator inertia values of a laundry load in the drum, based on the torque, acceleration, speed, and/or angular position of the drum at the beginning and the end of each dwell time. The estimated inertia values are transformed based on differing geometries of the laundry load, and water mass extraction is determined based on the transformed estimated inertia values.