Washing Machine Dosing Control for Precise Concentration
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Solution Overview
Problem
Institutional washing machines, particularly dishwashing machines, face challenges in accurately controlling product concentration due to large distances between the dispenser and concentration sensors, leading to significant over- or undershooting, which is economically and ecologically undesirable, and can cause glass corrosion from alkaline detergents.
Innovation Solution
A method that calculates the minimum opening time of the dispenser's solenoid valve and adjusts the dispensing time based on a moving average of previous dispensing events, ensuring precise concentration control without mechanical modifications, by measuring current concentration and feed rate, and preventing overdosing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a simple control function is used that initiates dispensing when concentration drops below setpoint and stops when setpoint is reached, then the control system is simple and easy to operate, but the final concentration becomes 50% or more above the setpoint causing economic loss, ecological harm, and glass corrosion
Solution Approach 1:
The system performs preliminary actions by calculating the minimum opening time of the output device before actual dispensing occurs. It also predicts the final concentration based on current feed rate and minimum opening time, allowing the controller to adjust the dosing time in advance to prevent overshooting the setpoint concentration.
Solution Approach 2:
The control system dynamically adapts by continuously monitoring the current feed rate and adjusting the dosing time accordingly. The system calculates the minimum opening time based on actual operating conditions rather than using fixed predetermined values, making the control dynamic and responsive to changing conditions.
2Adaptability or versatility
If the distance between the product reservoir outlet and the sensor is large, then the dispenser can be positioned flexibly in the washing machine, but the concentration control precision deteriorates due to delayed detection of product dissolution
Solution Approach 1:
The system uses feedback from the sensor to continuously monitor concentration and adjusts the dosing time based on the current feed rate calculated from previous dispensing events. This feedback mechanism compensates for the time delay introduced by the large distance between the dispenser and sensor, maintaining precision despite the extended measurement path.
3Quantity of substance
If the product block size decreases over time, then the detergent is gradually consumed as intended, but the feed rate decreases causing larger distance between spray nozzle and product block and worsening concentration control
Solution Approach 1:
The system dynamically calculates the current feed rate based on a moving average of the last n dispensing events. This allows the controller to adapt to the changing product block size and adjust the dosing time accordingly, maintaining concentration precision even as the feed rate varies during detergent consumption.
Solution Approach 2:
The system performs self-adjustment by automatically calculating the current feed rate from its own operational history and using this information to optimize subsequent dosing operations, eliminating the need for external calibration or manual intervention.
4Device complexity
If conventional dosing methods are used without considering minimum opening time, then the dispenser operation is simple, but significant over- and undershooting occurs leading to economic and ecological undesirable effects
Solution Approach 1:
The controller calculates the minimum opening time and predicts the final concentration before executing the dosing operation. This preliminary calculation allows the system to determine the optimal dosing time that prevents both overdosing and undershooting, reducing product waste while maintaining simple operation through automated calculations.
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 method optimizes product concentration in washing machines, reducing over- and undershooting, enhancing cleaning performance while minimizing economic and ecological impacts without requiring additional mechanical equipment or alterations.
Implementation Method 1
The present invention takes into account the minimum opening time the reversibly closable output device of the dispenser, typically a solenoid valve, has to be opened in order to ensure proper release of the product to be dispensed.
Implementation Method 2
U.S. Pat. No. 5,500,050 describes a detergent dispenser controller which determines the detergent concentration in a dishwasher's water tank by measuring the conductivity therein
Data Source
AI summary
The present invention relates to a method of controlling a dispenser for dosing a product in a washing machine leading to an optimized dosing result, a dispenser controller programmed with an algorithm to execute the method of the present invention as well as to the use of said dispenser for controlling dosing of a product in a washing machine.