Dishwasher Fill Control Using Pump Motor Feedback
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Solution Overview
Problem
Dishwashers face inefficiencies in energy consumption due to excessive water usage, with limited user control over liquid amounts and unreliable measurement devices, leading to variations in liquid pressure and component degradation.
Innovation Solution
A closed-loop feedback control system is implemented, using a monitoring device to track the pump motor's operating current and speed, which controls the water valve to optimize water fill levels during wash cycles, ensuring adequate liquid without overfilling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If liquid is provided for a predetermined duration through a conduit, then the dishwasher can complete the fill operation, but excessive liquid is consumed due to pressure variations and component degradation
Solution Approach 1:
The patent implements a feedback control system using a flowmeter to monitor the actual volume of liquid provided to the dishwasher. The controller receives feedback from the flowmeter and adjusts the fill duration dynamically, closing the loop between measurement and control action. This resolves the contradiction by enabling precise liquid quantity control while maintaining fill operation reliability through continuous monitoring and adjustment.
Solution Approach 2:
The system changes the control parameter from fixed predetermined time to variable time based on actual liquid flow measurement. The controller modifies the fill duration parameter dynamically according to feedback from the flowmeter, allowing adaptation to pressure variations and component degradation while maintaining consistent liquid volume delivery.
2Measurement precision
If flowmeters and water level sensors are used to monitor liquid amount, then measurement accuracy improves, but device complexity and cost increase
Solution Approach 1:
The flowmeter serves multiple functions: it measures liquid flow rate, determines total liquid volume provided, and provides feedback for control decisions. This multi-functionality achieves precise measurement without adding separate dedicated measurement devices, thereby limiting the increase in system complexity while improving measurement accuracy.
Solution Approach 2:
The flowmeter provides continuous feedback to the controller about liquid volume, enabling closed-loop control. This feedback mechanism achieves precise measurement accuracy by using the same measurement device for both monitoring and control purposes, avoiding the need for additional complex measurement systems.
3Reliability
If liquid is provided for an excessive duration to ensure sufficient amount, then fill reliability improves, but energy consumption increases
Solution Approach 1:
The feedback control system using the flowmeter enables the controller to stop liquid supply precisely when the required volume is achieved, rather than using excessive predetermined duration. This maintains fill sufficiency reliability through accurate volume monitoring while eliminating the energy waste associated with overfilling and extended pump operation.
Solution Approach 2:
The system uses the flowmeter's measurement capability to automatically determine when sufficient liquid has been provided, enabling self-regulating control without requiring external intervention or conservative overfilling. This achieves fill reliability through intelligent self-adjustment while minimizing energy consumption by avoiding excessive operation.
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 system reduces energy consumption by precisely controlling water usage, minimizing power surges and oscillations, and adapting to varying wash cycle demands, thereby enhancing water conservation and efficiency.
Implementation Method 1
The monitoring device generates an output relating to at least one of an operating current and a speed of the pump motor
Implementation Method 2
a pump motor driving the pump
Implementation Method 3
a valve for controlling the flow of water to the dishwasher
Data Source
AI summary
A control system for controlling a fill operation of a dishwasher having a pump and a pump motor driving the pump, and the dishwasher having a valve for controlling the flow of water to the dishwasher includes a monitoring device configured to be coupled to at least one of the pump and the pump motor. The monitoring device generates an output relating to at least one of an operating current and a speed of the pump motor. The control system also includes a controller configured to be operatively coupled to the valve, wherein the controller receives the output and is configured to operate the valve based on the output. The output relates to a fill condition of the dishwasher.