Drum Washing Machine Foam Control During Spin Run-Up
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Solution Overview
Problem
Conventional methods for removing foam in drum washing machines often lead to prolonged washing programs, increased water consumption, and inefficient spinning due to inadequate foam control.
Innovation Solution
A method involving a program-controlled drum washing machine with a sensor to monitor foam levels and adjust drum speed and water supply dynamically, ensuring efficient foam removal by adding a small amount of water continuously or discontinuously and adapting spin speed based on foam levels, with the option to increase or decrease speed accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If foam is detected during spin cycle in conventional washing machines, then the spinning is canceled or stopped, but this results in loss of productivity and extended washing time
Solution Approach 1:
The patent applies preliminary action by detecting foam during the rinse cycle before the spin cycle begins. The control unit monitors foam levels and prepares appropriate responses in advance, preventing foam-related spinning failures rather than reacting after detection during spinning. This resolves the contradiction by maintaining productivity while ensuring reliable foam control.
Solution Approach 2:
The patent implements feedback control by continuously monitoring foam levels during the rinse cycle and adjusting the spin cycle parameters accordingly. The control unit receives foam level signals and automatically adjusts spinning speed or activates foam removal measures, creating a closed-loop system that maintains both reliability and productivity.
2Reliability
If heating device is used to destroy foam as described in DE 41 04 151 A1, then foam removal effectiveness is improved, but energy consumption and treatment time increase significantly
Solution Approach 1:
The patent applies parameter changes by using mechanical parameters (drum rotation speed, water flow rate) instead of thermal parameters (heating temperature) to control foam. The control unit adjusts drum speed and water addition based on foam level detection, achieving effective foam removal without the high energy consumption associated with heating methods.
Solution Approach 2:
The patent replaces the thermal field (heating device) with a mechanical field (drum rotation and water flow control). By using mechanical agitation and water flow to disrupt foam structure, the system achieves foam removal effectiveness comparable to heating but with significantly lower energy consumption.
3Reliability
If large amounts of water are added to remove foam, then foam level is reduced effectively, but water consumption increases and washing program duration is extended
Solution Approach 1:
The patent applies dynamics by implementing dynamic adjustment of water flow rate and drum speed based on real-time foam level detection. Rather than adding large fixed amounts of water, the control unit continuously adapts water addition to match the actual foam generation rate, maintaining effective foam control while minimizing water consumption.
Solution Approach 2:
The patent uses partial action by adding only the necessary amount of water to control foam levels rather than excessive water addition. The control unit monitors foam levels and adds water in controlled increments, achieving sufficient foam removal without the water waste associated with excessive water addition methods.
4Reliability
If drum speed is reduced to control foam formation, then foam generation is minimized, but spinning productivity and water removal efficiency decrease
Solution Approach 1:
The patent applies preliminary action by controlling foam formation during the rinse cycle before spinning begins. The control unit monitors foam levels and adjusts drum speed or water addition in advance, preventing excessive foam accumulation that would require speed reduction during spinning. This maintains high spinning productivity while ensuring reliable foam control.
Solution Approach 2:
The patent implements dynamic adjustment of drum speed based on foam level detection. Rather than maintaining constantly reduced speed, the control unit adjusts speed dynamically - reducing it only when foam levels indicate a risk of excessive foam formation, then restoring higher speeds when foam levels are controlled. This maintains both foam control reliability and spinning productivity.
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 approach allows for quick and efficient foam removal, avoiding reapplication to laundry and minimizing water usage while automatically adapting to foam formation, ensuring effective foam control without lengthening the washing process.
Implementation Method 1
a sensor for determining a foam level hs and/or a negative temporal gradient (i.e. ds /dt) of a liquid-air mixture in the tub
Implementation Method 2
high speed spinning takes place after the main wash and rinse cycles
Data Source
Figure 1
AI summary
The invention relates to a method for eliminating foam in a drum washing machine having a program controller (12) for controlling a program sequence, a drum (2) rotatably supported in a detergent solution tub (1), a water supply system (8, 9, 10), a detergent solution discharge system disposed at the bottom of the detergent solution tub having a detergent solution pump (16), a drive motor (14) for the drum (2), and a sensor (15) for determining a foam level hs and/or a negative time gradient of the foam level (dhs/dt) of a fluid/air mixture present in the detergent solution tub (1), wherein a small amount of water is added continuously or discontinuously, with the detergent solution pump (16) switched on continuously or discontinuously, when foam is detected by the sensor (15) during a spinning run-up of the drum (2), that is, a continuous or continuous increase in the rotational speed of the drum (2). The invention further relates to a drum washing machine suitable for performing said method.