Washing Machine Drain Pump Control for Low-Flow Cut-Wave Operation
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Solution Overview
Problem
Existing washing machine control systems waste energy and cause mechanical stress by continuously powering the drainage pump with mains voltage during phases with minimal water flow, leading to reduced motor life and increased vibrations.
Innovation Solution
A control device that applies a constant delay time in each half-cycle of the mains voltage to the drainage pump motor, switching it to cut-wave mode during phases with minimal water flow, reducing power consumption and mechanical stress, and optimizing operation based on the washing program phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the discharge motor is continuously powered with full mains voltage during all washing phases, then the motor can respond immediately to drainage needs, but energy is wasted during low-load phases and mechanical stress increases
Solution Approach 1:
The control system dynamically adjusts the voltage supply mode based on the washing phase and load conditions. During high-load phases, full-wave mode is used for immediate response; during low-load phases, cut-wave mode is applied to reduce energy consumption while maintaining sufficient drainage capability.
Solution Approach 2:
The effective voltage parameter supplied to the discharge motor is changed based on operational requirements. By applying a constant delay time in each half-cycle during cut-wave mode, the RMS voltage is reduced from full mains voltage to an optimized level that balances energy savings with drainage performance.
2Loss of energy
If the discharge motor is switched off completely during phases with minimal water flow, then energy consumption is minimized, but the motor must be restarted frequently causing mechanical stress
Solution Approach 1:
Instead of completely switching off the motor or applying full voltage, a partial action is taken by applying cut-wave mode with reduced effective voltage. This maintains the motor in a ready state without full power, reducing both energy consumption and mechanical stress from frequent starts while keeping drainage capability available.
3Power
If the discharge motor operates with full mains voltage during all phases, then adequate drainage power is ensured, but vibrations increase during low-load phases
Solution Approach 1:
Different voltage supply qualities are applied to different operational phases. During high-load phases, full-wave mode provides adequate drainage power; during low-load phases, cut-wave mode reduces the effective voltage and consequently reduces vibrations while maintaining sufficient drainage capability for the reduced load.
4Loss of energy
If on-off control is used for the discharge motor, then energy is saved by stopping the motor during no-water phases, but the motor experiences sudden mechanical stresses at startup
Solution Approach 1:
The control system provides dynamic voltage adjustment between full-wave mode and cut-wave mode, eliminating the need for complete on-off cycling. This dynamic approach maintains motor readiness while reducing energy consumption, avoiding the mechanical stress of frequent startups that would result from complete shutdowns.
Data Source
AI summary
A device and method for controlling a drainage pump of a washing machine. The drainage pump is powered by a synchronous motor that is connected to a mains voltage bus by a switch. During one or more stages of a washing program the switch is operated to apply in each half cycle of the mains voltage a delay time from the zero setting of the mains voltage to cause the motor to operate in a cut-wave mode.