Washing Machine Lid Switch Redundancy for Reliable Motor Shutdown
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Solution Overview
Problem
Existing washing machine mode shifter systems are mechanically complex, costly, and unreliable, posing safety concerns due to potential failure to shut down when the washer lid is opened during operation.
Innovation Solution
A motor controller with a primary microprocessor and a secondary redundancy processor is used to automatically halt the washing machine operation, reducing wiring complexity and ensuring safe shutdown by monitoring the lid switch and motor RPM, with a pulse width modulated direct current voltage to prevent overheating of the mode shifter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional mode shifter system is used, then the washing machine can switch between agitation and spin modes, but the system becomes mechanically complex and less reliable
Solution Approach 1:
The patent replaces the conventional mechanical mode shifter system with an electronically controlled system. The motor controller receives signals from the control board and directly controls the motor to switch between agitation and spin modes, eliminating complex mechanical components while maintaining mode shifting functionality.
Solution Approach 2:
The motor controller serves multiple functions: it controls both agitation and spin modes, monitors motor RPM, detects lid switch status, and manages braking operations. This multi-functional electronic controller replaces what would otherwise require separate mechanical components for each function.
2Device complexity
If a single microprocessor is used to control washing machine operations, then the control system is simple, but reliability decreases due to potential processor failure
Solution Approach 1:
The patent implements a secondary microprocessor that stands by ready to take over control if the primary microprocessor fails. This backup processor is pre-configured with the same control logic and monitoring capabilities, providing a safety net before actual failure occurs.
Solution Approach 2:
The secondary microprocessor is essentially a copy of the primary microprocessor's functionality. It has identical control logic, monitoring capabilities, and can execute the same control algorithms, allowing it to seamlessly replace the primary processor if needed.
3Reliability
If the primary microprocessor fails to halt motor operation within a prescribed time window, then the system responds quickly to safety hazards, but control complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the secondary microprocessor continuously monitors the primary microprocessor's response to lid switch signals. If the primary processor fails to respond within a predetermined time window, the secondary processor detects this through the feedback loop and automatically intervenes to halt motor operation.
Solution Approach 2:
The secondary microprocessor is pre-programmed with the exact control logic needed to take over from the primary processor. It has ready-made routines for monitoring the primary processor, detecting failures, and executing the shutdown sequence, allowing immediate action without requiring complex real-time decision-making.
4Temperature
If pulse width modulated direct current voltage is applied to the mode shifter, then overheating is prevented, but energy control complexity increases
Solution Approach 1:
The patent applies pulse width modulated (PWM) direct current voltage to the mode shifter, delivering power in periodic pulses rather than continuous DC. By adjusting the duty cycle of these pulses, the system controls the average power delivered to the mode shifter, preventing overheating while maintaining effective operation.
Solution Approach 2:
The motor controller dynamically changes the voltage parameter delivered to the mode shifter using PWM technology. By varying the pulse width (duty cycle) and frequency, the system precisely controls the average power and heat generation in the mode shifter, allowing temperature management without complex cooling systems.
Data Source
AI summary
A method and control system for automatically halting operation of a washing machine by stopping operation of the washing machine motor is provided. The washing machine that implements the method includes a motor controller having a primary microprocessor and a secondary microprocessor which serves as a backup redundancy processor in the event there is a malfunction with the primary microprocessor or the primary microprocessor fails to halt washing machine operation within a prescribed window of time. The primary microprocessor controls operation of all of the washing machine electrically controlled components. The secondary microprocessor is electrically connected to a lid switch and the washing machine motor and is configured to halt operation of the motor in response to the primary microprocessor failing to halt motor operation after the lid is open.