Washing Machine Motor Direction Switching for Overload Protection
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Solution Overview
Problem
Washing machines with motors designed to draw more current in one direction struggle with operational safety when overloaded or under improper conditions, leading to potential motor strain and overheating, necessitating a solution to prevent overacceleration and energy inefficiency.
Innovation Solution
A control unit that monitors motor operation and switches the rotation direction from high-current to low-current direction when errors are detected, ensuring the motor operates safely by rotating in the direction with lower torque and current draw, thereby preventing overacceleration and overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the motor is designed to draw more current in the first direction to provide greater torque, then the motor can achieve higher acceleration and faster spin-drying, but the motor becomes vulnerable to overacceleration and overheating when errors occur during operation
Solution Approach 1:
When an error is detected during motor operation in the first direction, the control unit inverts the rotation direction by switching to the second direction. This inversion allows the motor to continue operating without stopping, utilizing the lower current draw and torque characteristics of the second direction to prevent harmful effects while maintaining productivity.
Solution Approach 2:
The control unit changes the operational parameters of the motor by switching between two distinct rotation directions with different current and torque characteristics. This parameter change allows dynamic adaptation to error conditions, transforming a potentially dangerous high-torque state into a safe low-torque state while maintaining motor operation.
2Reliability
If the motor is stopped and waited for a while when an error is detected, then the motor can prevent overheating and damage, but the washing program is interrupted and time is lost
Solution Approach 1:
The control unit performs a preliminary direction switch to the second rotation direction before the motor can overheat or be damaged. This preliminary action maintains continuous motor operation and keeps the washing program running, preventing time loss while still protecting the motor from harmful conditions.
Solution Approach 2:
Instead of stopping the motor to prevent overheating, the system inverts the rotation direction to the second direction. This inversion allows the motor to continue running with reduced current draw and torque, thereby preventing overheating without interrupting the washing program or losing time.
3Productivity
If the motor rotates in the first direction again after being stopped, then the motor can resume the spin-drying function, but the motor may suddenly overaccelerate and cause further damage if the error is not corrected
Solution Approach 1:
When an error is detected, the control unit inverts the rotation direction to the second direction instead of resuming the first direction. This inversion prevents overacceleration and harmful effects while maintaining spin-drying functionality, as the motor continues to rotate and drive the drum, albeit in the opposite direction with lower torque.
Solution Approach 2:
The error condition that would normally cause overacceleration and damage in the first direction is converted into a beneficial situation by switching to the second direction. The lower current draw and torque in the second direction transform a potentially harmful high-stress operation into a safe, continuous operation that maintains productivity without causing damage.
Data Source
Figure 1~2
AI summary
The washing machine (1) of the present invention comprises a drum (2) wherein the laundry to be washed is placed, a motor (3) providing the drum (2) to rotate in the rotational speed suitable for the washing program consisting of main washing, rinsing and spin-drying steps and a control unit (4) that controls operation of the motor (3) with respect to the washing program selected by the user.