Draining Pump Cycling for Air Bubble Removal in Laundry Machines
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Solution Overview
Problem
Laundry washing machines experience inefficiencies and incorrect alarm notifications due to air or air bubbles at the pump inlet, leading to prolonged draining phases and potential false interpretations of pump malfunctions.
Innovation Solution
A method involving the activation and deactivation of the draining pump with varying off-time periods based on drainage flow rates, allowing for the expulsion of air and ensuring proper priming, thus maintaining nominal flow rates without interrupting the washing program or displaying false alarms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the draining pump operates continuously to drain liquid, then the draining function is maintained, but air bubbles accumulate at the pump inlet causing reduced flow rate and prolonged draining time
Solution Approach 1:
The draining pump operates in periodic cycles with alternating on-periods and off-periods. During on-periods, the pump drains liquid; during off-periods, air bubbles can escape from the pump inlet. This periodic operation prevents air accumulation that would otherwise reduce flow rate and extend draining time, thereby maintaining high productivity without excessive time loss.
Solution Approach 2:
The pump performs preliminary draining operations to remove liquid before air bubbles become problematic. By operating in cycles, the system proactively prevents air accumulation rather than reacting to it, maintaining optimal flow rates throughout the draining process.
2Reliability
If the draining pump operates continuously, then liquid is drained efficiently, but air bubbles cause false low flow rate detection leading to incorrect alarm notifications
Solution Approach 1:
The periodic on/off operation of the draining pump allows air bubbles to escape during off-periods, preventing the false low flow rate conditions that trigger incorrect alarm notifications. This ensures reliable operation without spurious alarms.
Solution Approach 2:
The off-periods, which might seem to reduce draining efficiency, actually serve the beneficial function of allowing air bubbles to escape. This converts what would be a harmful condition (air accumulation causing false alarms) into a beneficial outcome (air removal preventing false alarms).
3Productivity
If the draining pump is stopped frequently to remove air bubbles, then air is expelled and flow rate is maintained, but the draining phase becomes more complex with multiple activation cycles
Solution Approach 1:
The control unit implements a systematic periodic operation pattern with defined on-periods and off-periods. This structured approach manages the complexity of multiple activation cycles through automation, maintaining draining efficiency without requiring complex manual intervention or overly complicated control logic.
Solution Approach 2:
The control unit monitors flow rate conditions and automatically adjusts pump operation cycles accordingly. This feedback mechanism simplifies control by allowing the system to self-regulate the number and duration of activation cycles based on actual draining conditions, preventing excessive complexity.
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 reduces the total draining time and prevents incorrect alarm notifications, ensuring the washing program completes efficiently without false malfunctions detected.
Implementation Method 1
a rotating element, or impeller, which increases the pressure and flow of the liquid towards an outlet of the pump itself
Implementation Method 2
the presence of air, or air bubbles, at the pump inlet... Air or air bubbles, in fact, may be easily found at the bottom of the washing tub where the pump is connected
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present invention relates to a method for washing laundry in a laundry washing machine (1) of the type comprising a washing tub (3) external to a rotatable washing drum (4) adapted to receive laundry and a draining device (25) comprising a draining pump (26) for draining liquid from the washing tub (3). The method comprises at least a draining phase (148) for draining liquid from the washing tub (3) by means of said draining device (25). The draining phase (148) comprises the steps of: a) activating (182) the draining pump (26); b) checking (185) the drainage flow rate (FR) of the liquid flowing through the draining pump (26); if the drainage flow rate (FR) is above or equal to a minimum flow rate threshold, then d) operating (199) the draining pump (26) and de-activating (186) the draining pump (26) when an end-draining condition is reached (194), if the drainage flow rate (FR) of the liquid flowing through the draining pump (26) is below a minimum flow rate threshold, then: e1) operating (184) the draining pump (26) for an on-time period (TON); e2) de-activating (186) the draining pump (26); e3) stopping (188) the draining pump (26) for an off-time period (TOFF; TOFF(n)); and e4) going back to step a).