Washing Machine Recirculation Control for Load Detection Accuracy
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Solution Overview
Problem
Conventional laundry care appliances face challenges in accurately detecting and controlling the laundry load, leading to inefficient wetting of laundry due to varying amounts of washing liquid, which affects the pumping process and the overall washing efficiency.
Innovation Solution
A laundry care appliance with a controller that activates and deactivates the pumping device based on the duration of the pumping-over period and volume flow threshold, utilizing a pressure detection device and power detection element to determine the laundry load, ensuring effective wetting and efficient liquid circulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pumping device operates continuously to pump washing liquid out of the tub, then the tub can be emptied completely, but the laundry load detection becomes inaccurate and washing liquid is wasted
Solution Approach 1:
The controller performs laundry load detection before activating the pumping device, establishing the initial state of the system. This preliminary detection ensures accurate load measurement is obtained before any washing liquid is removed or circulated, preventing detection errors that would occur during active pumping.
Solution Approach 2:
The system alternates between detection phases and pumping phases. The controller periodically activates the pumping device for controlled intervals, then stops to allow for detection. This periodic operation enables accurate laundry load detection at specific moments while still achieving tub emptying over time, resolving the contradiction between continuous pumping and accurate detection.
2Measurement precision
If the pumping device operates continuously to circulate washing liquid back into the laundry drum, then the laundry can be wetted effectively, but the detection of laundry load becomes impossible and energy is consumed unnecessarily
Solution Approach 1:
The controller implements periodic pumping operations with controlled intervals. The pumping device is activated for specific durations to circulate washing liquid and wet the laundry, then deactivated to allow for laundry load detection. This periodic pattern ensures both effective laundry wetting and accurate detection capability, preventing continuous energy consumption.
Solution Approach 2:
The controller uses feedback from laundry load detection to regulate pumping device operation. Detection results inform the controller when to activate or deactivate the pumping device, creating a closed-loop control system. This feedback mechanism ensures pumping occurs only when necessary for wetting laundry, avoiding unnecessary energy consumption while maintaining detection precision.
3Use of energy by moving object
If the pumping device is deactivated early when volume flow decreases, then energy consumption is reduced, but the tub may not be completely emptied
Solution Approach 1:
The controller continuously monitors volume flow parameters during pumping operation and uses this feedback to determine when to deactivate the pumping device. By analyzing flow rate changes and comparing against predefined thresholds, the controller can accurately determine when tub emptying is complete or when continued pumping would only consume energy without significant additional emptying benefit.
Solution Approach 2:
The system changes operational parameters (volume flow thresholds, pumping duration) based on detection results and operational phase. During different stages of the washing cycle, different flow thresholds are applied to balance energy consumption and emptying completeness. This parameter adaptation allows the system to optimize the trade-off between energy use and emptying effectiveness.
4Productivity
If the pumping device operates at high capacity to wet laundry quickly, then washing time is reduced, but the laundry load detection accuracy deteriorates due to varying washing liquid amounts
Solution Approach 1:
The controller performs laundry load detection before initiating high-capacity pumping operations. This preliminary detection establishes the baseline load state, allowing the system to subsequently operate at high pumping capacity for efficient laundry wetting without compromising the accuracy of the initial load measurement. The detection occurs when washing liquid volume is stable and known.
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 allows for precise detection of the laundry load, enabling effective wetting and efficient liquid circulation, even at lower fill levels, and improves the accuracy of laundry load determination compared to conventional methods.
Implementation Method 1
a pumping device for pumping washing liquid being arranged in the line, the pumping device being designed to pump washing liquid out of the tub through the drain opening
Implementation Method 2
the pumped-out washing liquid through the line and through the inlet nozzle back into the laundry drum arranged in the tub
Implementation Method 3
the controller being designed to deactivate the pumping operation of the pump-over device, to end the pump-over time section and to record the duration of the pump-over time section if the volume flow of the washing liquid pumped through the pump-over device falls below a volume flow threshold value
Implementation Method 4
to supply the pumped-out washing liquid through the line and through the inlet nozzle back into the laundry drum arranged in the tub in order to wet the laundry in the laundry drum again with washing liquid
Data Source
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AI summary
The invention relates to a laundry care appliance (100) with an outer tub (105), an inner tub (107), an outlet opening (111), an inlet nozzle (115), a conduit (113) which fluidically interconnects the outlet opening (111) to the inlet nozzle (115) and a recirculating pump device (117) for pumping wash fluid. A controller (123) is designed to activate, at the beginning of a recirculating period, a conveying operation of the recirculating device (117) in order to pump the wash fluid out through the outlet opening (111) from the outer tub (105), and to guide the pumped out wash fluid back through the conduit (113) and through the inlet nozzle (115) to the inner tub; to deactivate the conveyor operation of the recirculating pump (117), to end the recirculation period and to detect the duration of the recirculation period when the volume flow of the wash fluid pumped through the recirculation device exceeds a volume flow threshold value; and to determine the laundry load in the inner tub in accordance with the detected duration of the recirculating period.