Washing Machine Clutch Control Using AC-Synchronized Cam Switch Pulses
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Solution Overview
Problem
Conventional washing machines face issues with the clutch unit's coupling being damaged due to incorrect positioning of the cam switch in poor power supply environments, leading to errors in pulse measurement and incomplete coupling changes between washing and dewatering modes.
Innovation Solution
A washing machine design that includes a cam switch which outputs pulses synchronized with the AC power frequency, allowing for precise control of the clutch unit's operation modes by counting pulses and determining elapsed times to ensure accurate positioning of the cam switch, preventing coupling damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the clutch motor stops after a predetermined time based on rated voltage and frequency, then the control method is simple, but the cam stop position becomes inaccurate in poor power supply environments
Solution Approach 1:
The cam switch provides real-time feedback by outputting pulses synchronized with AC power frequency. The controller counts these pulses to determine cam position and controls the clutch motor to stop when the cam reaches the correct position, rather than using a fixed time delay that doesn't account for power supply variations.
Solution Approach 2:
The patent replaces the mechanical timing method (based on rated voltage and frequency) with an electrical pulse counting method. The cam switch generates electrical pulses that are counted by the controller to precisely track cam position, substituting mechanical timing assumptions with electrical measurement.
2Device complexity
If the cam switch output pulses are not synchronized with AC power frequency, then the pulse counting method is simpler, but the cam position determination becomes inaccurate
Solution Approach 1:
The cam switch outputs pulses with a period synchronized to the AC power frequency. This periodic action at a known frequency allows the controller to accurately determine time elapsed and cam position by counting pulses, since each pulse corresponds to a known time interval based on the AC frequency.
3Productivity
If the clutch motor stops without precise cam positioning, then the operation speed is faster, but the coupling becomes damaged
Solution Approach 1:
The controller uses feedback from the cam switch pulses to determine when the cam has reached the correct stop position. The clutch motor is controlled to stop only when the pulse count indicates proper positioning, preventing premature stopping that would damage the coupling while still enabling rapid mode switching.
Data Source
AI summary
A washing machine includes a main body; a washing tub provided inside the main body to receive washing water; a dewatering tub rotatably provided inside the washing tub; a driving device configured to supply a rotational force; a clutch unit to operate in a first mode in which the rotational force generated in the driving device is transmitted to the dewatering tub and a second mode in which the rotational force is not transmitted to the dewatering tub; a clutch motor to switch an operation mode of the clutch unit; and a cam switch switched from a switch-off state to a switch-on state, wherein the cam switch outputs pulses having the same period as a frequency of AC power supplied to the clutch motor in the switch-on state, and when the cam switch is switched from the switch-off state to the switch-on state, the clutch unit is stopped.