Washing Machine Laundry-Amount Detection Using Motor Current Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional washing machines face challenges in accurately determining the amount of laundry, especially with sensorless motors, leading to inefficiencies in spin-drying operations, increased energy consumption, and potential damage due to unbalanced loads during high-speed rotation.
Innovation Solution
The washing machine employs a controller that measures the amount of laundry by analyzing current values during motor operation, dividing them into maintenance, acceleration, and deceleration periods, and using counter-electromotive force to calculate the amount, allowing for precise determination and adaptive rotational speed control from low to high speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current is measured at the time of starting the motor to determine the amount of laundry, then the measurement process is simple, but the measurement precision is poor and cannot accurately determine small amounts of laundry
Solution Approach 1:
The patent applies preliminary action by measuring current during motor operation phases (acceleration, maintenance, deceleration) before the actual spin-drying process. This allows the system to collect multiple current measurements under different operational conditions, enabling more accurate laundry amount determination through comparative analysis rather than relying on a single starting-current measurement.
Solution Approach 2:
The patent implements feedback by continuously monitoring current values during motor operation and using these measurements to adjust and determine the laundry amount. The controller compares current measurements taken at different motor speeds and phases, using the feedback from these measurements to accurately determine the laundry amount and adjust motor rotational speed accordingly.
2Productivity
If the motor is rotated at high speed for spin-drying, then water removal efficiency is improved, but the washing machine may be damaged due to unbalance when laundry is tangled or collected at one side
Solution Approach 1:
The patent applies dynamics by adjusting the motor rotational speed based on the determined laundry amount. The controller dynamically sets the maximum rotational speed during spin-drying according to the laundry characteristics, ensuring safe operation for small amounts of laundry while allowing high-speed operation for larger loads. This dynamic speed adjustment prevents damage from unbalance while maintaining water removal efficiency.
Solution Approach 2:
The patent changes the operational parameter (rotational speed) based on the determined laundry amount. The controller modifies the motor's rotational speed parameter adaptively, setting lower maximum speeds for small laundry amounts and higher speeds for larger amounts, thereby optimizing both safety and efficiency according to the actual load conditions.
3Loss of time
If the amount of laundry is not precisely measured, then the measurement process is simple, but the washing time increases and energy consumption increases due to extended spin-drying operation
Solution Approach 1:
The patent replaces traditional mechanical or sensor-based laundry measurement methods with an electrical measurement approach. By measuring current consumption during motor operation and analyzing it in relation to motor speed and operational phase, the system determines laundry amount electrically, achieving precise measurement without additional mechanical sensors or complex measurement mechanisms.
4Device complexity
If sensorless motor is used to reduce device complexity, then the device complexity is reduced, but positional alignment is difficult at the time of starting the motor, whereby variation in the measured amount of laundry is increased
Solution Approach 1:
The patent applies periodic action by measuring current at multiple distinct phases of motor operation (acceleration, maintenance, deceleration) rather than relying on a single starting measurement. This periodic sampling of current values throughout the motor's operational cycle allows the system to overcome the positional alignment issues of sensorless motors and accurately determine laundry amount through comparative analysis of measurements taken at different operational points.
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 method enables rapid and precise measurement of laundry, reducing washing time and energy consumption, and preventing motor damage by accurately adjusting spin-drying speeds based on load quantity.
Implementation Method 1
a motor 270 connected to the drum 134 to rotate the drum 134
Implementation Method 2
a current-sensing unit 280 to measure current of the motor 270
Implementation Method 3
determine the amount of laundry 1420 based on a current value 2820 received from the current-sensing unit 280, the rotational speed of the motor 270, and counter-electromotive force
Implementation Method 4
a spin-drying operation is performed in the washing cycle and the rinsing cycle as well as in the spin-drying cycle in order to remove water from the laundry. In the spin-drying operation, a motor is rotated at a high speed. As a result, centrifugal force is applied to the laundry in the drum, whereby water is removed from the laundry
Data Source
AI summary
An amount of laundry that is introduced into a washing machine is calculated using gravity and inertia applied during the operation of a motor, whereby the amount of laundry is precisely measured and effects of the initial position of the laundry and the movement of the laundry are minimized. In addition, a measured current of the operated motor is used to determine the amount of laundry without a sensor. Furthermore, the rotational speed of the motor is controlled stepwise from a low speed to eliminate variation due to vibration. Moreover, the characteristics of gravity in the low-speed maintenance period are used to effectively calculate the amount of laundry, and the characteristics of inertia in the acceleration period are also used, whereby it is possible to precisely determine the amount of laundry. Consequently, it is easy to commence the spin-drying operation, thereby reducing washing time and saving energy.