Single-Phase Dishwasher Pump Control for Variable Spray Velocity
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Solution Overview
Problem
Single-phase motors in dishwashers are limited by inadequate speed control, low starting torques, lack of feedback, and inefficiency, leading to vibration and noise issues, which hinder advanced wash performance and energy efficiency.
Innovation Solution
Implementing a pump system with a single-phase motor responsive to a variable frequency single-phase alternating current input, coupled with a pump stabilizer and control circuitry to adjust spray velocity and address torque pulsations, while maintaining cost and complexity at a lower level compared to three-phase motor systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single-phase motors are used in pump systems, then cost and complexity are reduced, but speed control capability and starting torque are inadequate
Solution Approach 1:
The patent applies parameter changes by varying the frequency of single-phase AC power supplied to the motor. The control circuit adjusts frequency from 20-120 Hz to achieve different spray velocities (e.g., 20-40 Hz for low velocity, 40-60 Hz for medium, 60-120 Hz for high velocity), enabling speed control comparable to three-phase systems while maintaining single-phase simplicity
Solution Approach 2:
The system implements dynamics by making the motor speed variable through frequency modulation. The pump motor operates at different rotational speeds depending on the required spray velocity, allowing the system to adapt to different wash cycle requirements dynamically rather than operating at fixed speed
2Device complexity
If single-phase motors are used in pump systems, then cost and complexity are reduced, but starting torque is low
Solution Approach 1:
The patent applies preliminary anti-action by using a pump stabilizer that counteracts torque pulsations before they affect the pump operation. The stabilizer includes a flywheel or inertia element that smooths out the pulsating torque from the single-phase motor, providing consistent starting torque without requiring a complex three-phase motor
Solution Approach 2:
The system uses periodic action by operating the single-phase motor at optimized frequency ranges that maximize torque output. The control circuit selects specific frequency bands (e.g., 20-40 Hz, 40-60 Hz, 60-120 Hz) that provide adequate starting torque for different operational requirements
3Device complexity
If single-phase motors are used in pump systems, then simplicity is maintained, but vibration and noise increase
Solution Approach 1:
The patent applies anti-weight by incorporating a pump stabilizer with a flywheel or counterbalancing inertia element. This stabilizer counteracts the vibration and torque pulsations generated by the single-phase motor, reducing noise and vibration transmission to the dishwasher structure without adding complex active vibration control systems
Solution Approach 2:
The system uses beforehand cushioning by placing the pump stabilizer between the motor and the pump/mounting structure. The stabilizer absorbs and dampens vibrations before they propagate through the appliance, reducing noise and harmful vibrations in advance
4Device complexity
If single-phase motors are used in pump systems, then cost is reduced, but energy efficiency and wash performance are limited
Solution Approach 1:
The patent applies feedback by using sensors (e.g., flow sensors, pressure sensors, or motor current sensors) to monitor pump operation and spray characteristics. The control circuit adjusts the motor frequency in response to feedback signals to optimize wash performance for different cycle requirements, enabling sophisticated control comparable to three-phase systems with simpler hardware
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 configuration achieves performance comparable to variable speed and three-phase motor systems without increasing cost or complexity, improving wash efficiency and reducing noise and vibration.
Implementation Method 1
pump motors and control circuitry used to dispense a washing fluid throughout the appliance
Data Source
AI summary
An appliance for washing objects in which is employed a pump system for varying the spray velocity of washing fluid dispensed from spray jets affixed at an angle relative to a spray arm. In one embodiment, the pump system includes a pump having a pump motor such as a synchronous motor responsive to a variable frequency, single-phase alternating current input. The pump system also includes a pump motor control circuit configured to vary the frequency and voltage of the input, which in one example effectuates changes in the rotational speed of the pump motor in accordance with one or more operational cycles. The pump motor control circuit incorporates in one example a rectifier and an inverter that permits operation of the appliance when coupled to supply mains.