Method for operating a household appliance and household appliance
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Solution Overview
Problem
Existing washing machines face issues with detergent loss and contamination during the washing process due to sudden pressure forces and pressure waves, which cause the non-return valve to open prematurely, allowing detergent to escape and contaminated water to re-enter the tub.
Innovation Solution
Operating the pump in a direction opposite to the main direction during specific phases of the washing cycle builds additional pressure to keep the non-return valve closed, reducing detergent loss and preventing contaminated water from re-entering the tub, without requiring additional components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a check valve is used to prevent detergent loss and contamination, then detergent retention and contamination prevention are improved, but the check valve may open prematurely due to pressure forces and pressure waves during washing
Solution Approach 1:
The pump is operated in reverse direction before the main draining phase to generate counter-pressure that actively prevents the check valve from opening prematurely. This preliminary anti-action counteracts the pressure forces and waves that would otherwise cause detergent loss and contamination, ensuring the check valve remains reliably closed during critical washing phases.
Solution Approach 2:
The reverse pump operation is performed in advance of the main draining operation, preparing the system by establishing counter-pressure and ensuring the check valve is securely closed before detergent is added and before the washing cycle begins. This preliminary action prevents harmful effects before they can occur.
2Productivity
If the pump operates only in the main draining direction, then the draining efficiency is improved, but the check valve cannot be kept reliably closed during pressure surges
Solution Approach 1:
The pump operates in a periodic cycle, alternating between reverse direction (to maintain check valve closure with counter-pressure) and main draining direction (to achieve efficient water removal). This periodic switching ensures both reliable check valve closure during pressure surges and high draining efficiency when needed, resolving the contradiction between the two requirements.
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 significantly reduces detergent loss and prevents contamination of laundry items by ensuring the non-return valve remains closed, enhancing washing performance without additional costs or components.
Implementation Method 1
The pumping action moves a column of water acting on the check valve away from it, thus reducing or eliminating the closing forces exerted by the water column on the check valve. This effect is subsequently referred to as pump suction.
Implementation Method 2
the pump is operated in a direction opposite to the main direction, at least during a predetermined time interval during an operating phase of the household appliance, particularly during the washing phase. This generates pump pressure at the check valve, which forces the check valve towards the closed position.
Implementation Method 3
The check valve can be in the form of a flap or a ball, which is pushed towards the closed position by the residual water in the drain line. This occurs due to the water column that forms in the drain line and the buoyant force acting in the closing direction of the check valve.
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a method for operating a household appliance (1) for the care of laundry items (6), in which liquid is filled into a tub (3) of the household appliance, in particular during a washing phase (22) of an operating program, and the liquid and/or detergent solution is pumped out of the tub (3) via a drain line (11) during a subsequent pumping out phase (24), wherein a pump (12) is operated in a main direction (18) for pumping out the liquid and/or detergent solution, and during the pumping out a check valve (16) is moved out of a closed position, in which the drain line (11) is sealed with respect to the tub (3), into an open position in which the drain line (11) is fluidly connected to the tub (3), wherein at least during a predefined time interval (25), in particular during the washing phase (22), the pump (12) is operated in a direction (20) counter to the main direction (18), and by this means, a pump pressure (2) is established at the check valve (16) by means of which the check valve (16) is pushed into the closed position.