EP3172367A1

EP3172367A1 - Household appliance comprising a recirculating pump system

Info

Publication number: EP3172367A1
Application number: EP15731987.2A
Authority: EP
Inventors: Antonio BARRADO FRANCO; Andreas Bischof; Andreas Hanau; Hartmut Schaub
Original assignee: BSH Hausgeraete GmbH
Current assignee: BSH Hausgeraete GmbH
Priority date: 2014-07-23
Filing date: 2015-07-01
Publication date: 2017-05-31
Also published as: CN106574420B; WO2016012211A1; CN106574420A; DE102014214351A1

Abstract

The invention relates to a household appliance (100) having a recirculating pump system which comprises a first line (105), a second line (111), an outer tub (107) and a wash liquid reservoir (109). The first and second lines (105, 111) connect the outer tub (107) to the wash liquid reservoir (109). The recirculating pump system comprises a pump (113) for pumping wash liquid in order to remove a biofilm from an inner surface of the first and second lines (105, 111), the outer tub (107) and the wash liquid reservoir (109), and household appliance (100) comprises a device for detecting a flow rate of the wash liquid in the recirculating pump system.

Description

Household appliance with a pumping system

The present invention relates to a household appliance with a pumping system. In household appliances, washing liquor is often stored in order to be used for the washing process at a certain time. For this purpose, household appliances usually contain liquor storage in which wash liquor can be stored. The stored wash liquor can be supplied to the washroom for the washing process by means of lines. In certain places in household appliances, which are in contact with wash liquor, wet surfaces form, which are covered after a certain time with biofilms. The biofilms are increasingly forming in places in household appliances, where appropriate living conditions for microorganisms are present and where a diverse entry of germs is possible. The microorganisms can be introduced into the liquor storage by the water supplied to the household appliances. The water can also be subsequently contaminated by microorganisms from the air or from other components of the household appliance.

Microorganisms are microscopically small animals that produce unicellular organisms and multicellular organisms, e.g. Include algae, archaea, amoebae, flagellates, bacteria, protozoa and viruses. The microorganisms present in the water are responsible for the formation of a biofilm in a liquor store in household appliances. A biofilm consists of a mucus layer of matrix structure comprising extracellular polymeric substances which forms hydrogels in conjunction with water. A biofilm may contain, among other things, polysaccharides, proteins, lipids and nucleic acids.

While visible biofilms on household appliances can usually be removed by the user by hand, in home appliances there are many externally inaccessible areas where biofilms can also form. These biofilms are usually only noticed by the perception of unpleasant odors caused by microorganisms in the biofilm. The unpleasant odors and discolorations of surfaces of the household appliance, which are based on the formation of biofilms, the overall hygienic impression of the device in question. Ordinary cleaning methods are usually unsuccessful and not of long duration. Known methods for preventing the formation of biofilms are often based on the treatment of materials and components with biocides. Biocides include various drugs against microorganisms. The use of biocides, however, has proven to be unsuitable to prevent biofilm formation sustainably. Although microorganisms settling on biocidal surfaces are killed. However, other microorganisms settle on the dead microorganisms. Once the layer of dead microorganisms has sufficient thickness, the biocide of the component material can no longer reach the microorganisms on the layer surface. As a result, the biocide becomes ineffective after a certain period of time and the microorganisms continue to grow unhindered.

Alternatively, cleaning agents that can suppress the growth of microorganisms are used. Corresponding detergents, however, often contain environmentally critical substances which, moreover, can be hazardous to the health of the user or cause damage to the components of household appliances. The successful use of cleaning agents depends not only on the active ingredient concentration of the cleaning agent but also on the duration of action. For components, which are installed inside the household appliance, both can not be sufficiently ensured, whereby a sufficient cleaning effect is omitted. It is the object underlying the invention to provide a household appliance in which a biofilm formed on an inner surface of a pumping system can be efficiently removed.

This object is achieved by articles having the features according to the independent claims. Advantageous embodiments of the invention are the subject of the figures, the description and the dependent claims.

According to a first aspect of the invention, the object is achieved by a household appliance with a pumping system comprising a first conduit, a second conduit, a tub and a liquor storage, wherein the first and second conduit connects the tub with the liquor storage, and wherein the Umpumpsystem comprises a pump for pumping, in particular for pumping, of washing liquor for removing a biofilm on an inner surface of the first and second line of the tub and the liquor storage, wherein the household appliance comprises means for detecting a flow rate of wash liquor in the pumping system. As a result, the technical advantage is achieved, for example, that a biofilm, which can form over time on an inner surface of the pumped circulation system, is removed by pumping over washing liquor in the pumping system. The detergent components in the detergent mean that the biofilm can be effectively detached from the inner surfaces of the pumped circulation system. As a result, a comparable cleaning effect can be achieved, as with a commercially available washing machine cleaner. The effectiveness of removing the biofilm depends on the flow rate of the wash liquor in the pumping system. With a high flow rate of the wash liquor, a biofilm is more easily removed than at a low flow rate. To regulate the flow rate of the wash liquor in the pumping system, means for detecting a flow rate of wash liquor in the pumping system are required. The device can detect when a change in the flow rate of the wash liquor must be effected by a change in the pump power of the pump. The change in the pumping power as a function of the flow velocity detected by the device can be done automatically. This can ensure effective removal of the biofilm in the pumping system.

It is therefore provided in particular that the domestic appliance comprises the device for detecting a flow rate of wash liquor in the pumping system in order to regulate the flow rate of the wash liquor in the pumping system by means of an automatic change of a pumping capacity of the pump in dependence on the flow velocity detected by the device for detecting a flow velocity So to steer.

This means in particular that, depending on the detected flow rate, a pumping power of the pump is automatically regulated or controlled. By regulating or controlling the pumping power, the flow rate changes, so that the biofilm can be effectively released according to the flow velocity. For example, if it is determined that the sensed flow rate is insufficient to effectively dislodge a biofilm, then according to one embodiment, the pump power is increased from a current pump power by a predetermined value. In particular, according to one embodiment, it is provided that the pumping power is increased to a predetermined pumping power value when, for Example is found that the detected flow rate is insufficient to effectively detach a biofilm

The decision as to whether or not to increase the pumping power, that is, whether or not the pumping power is sufficient to effectively dissipate the biofilm, is made based on a flow rate threshold, in one embodiment. If the detected flow velocity is less than the flow velocity threshold value, according to one embodiment it is provided that the pumping power is increased by a current value from a momentary pump power or increased to a predetermined pump power value.

The predetermined value and / or the Strömungsgeschwindigkeitsschwellwert and / or the predetermined pump power value are determined or determined, for example by means of experiments.

In one embodiment it is provided that a control device is provided, which is designed to control the pump power of the pump in dependence on the detected flow velocity, that is to regulate automatically. For example, the controller includes a memory in which the flow velocity threshold and / or the predetermined value and / or the predetermined pump power value are stored.

In one embodiment of the method, the following step is provided: detecting the flow rate of wash liquor in the pumping system by means of the device for detecting a flow velocity. In a further embodiment of the method, the following step is provided: regulating (ie in particular controlling) the flow rate of the wash liquor in the pumping system by means of an automatic change of a pumping capacity of the pump as a function of the flow velocity detected by the device for detecting a flow velocity. The regulation (ie, in particular the control) is carried out, for example, by means of the control device.

A household appliance is a device that is used for household management. This may be a large household appliance, such as a washing machine, a tumble dryer, a dishwasher, or a refrigerator, such as a refrigerator, a freezer or a Kühlgefrierkombination. But that can also be one Household small appliance, such as a water heater, a coffee machine, a food processor or a vacuum cleaner.

In an advantageous embodiment of the household appliance, the pump is integrated in the first line.

As a result, the technical advantage is achieved that the integrated pump in the first line allows a rapid discharge of the wash liquor from the tub. The pump can also regulate the flow rate of the wash liquor. In addition, the integrated pump conducts the wash liquor into the liquor storage tank at a high pressure and at a high flow rate. A change in the flow rate of wash liquor caused by the pump may be detected by the means for detecting a flow rate of wash liquor. As a result, a sufficient distribution of the wash liquor is achieved on a majority of the inner surfaces of the lines, the liquor storage and the tub, and thus a complete removal of the biofilm is achieved.

In an advantageous embodiment of the household appliance, the pumping system comprises a second pump, which is integrated in the second line. As a result, the technical advantage is achieved that a rapid discharge of the wash liquor from the liquor storage is made possible in the tub by the second pump. The second pump can change the flow rate of wash liquor in the second conduit. The second pump can direct the wash liquor from the liquor storage to the tub at a high pressure and high flow rate. This leads to a splashing of the wash liquor when entering the tub and thereby allows an advantageous distribution of the wash liquor in the tub. Due to the sufficient distribution of the wash liquor on the inner surface of the tub, a complete detachment of the biofilm can be achieved. In an advantageous embodiment of the household appliance, the device for detecting a flow rate of wash liquor, a first level sensor for detecting a first level of wash liquor in the tub, and a second level sensor for detecting a second level of wash liquor in the liquor storage, wherein the means for detecting a flow velocity of Washing liquor is adapted to determine the flow rate of wash liquor based on a comparison between the first and the second level.

Thereby, the technical advantage is achieved that a determination of the flow rate of wash liquor is made possible in the pumping system via the indirect measurement of two levels without an additional component is required in the household appliance. When a pump conveys the wash liquor in the pumping system at a high flow rate from the tub through the first conduit into the liquor storage, then the first fill level of the wash liquor in the tub decreases and the second fill level of the wash liquor in the liquor store increases. By comparing the first and the second fill level, it is possible to deduce the flow rate of the wash liquor in the pump-around system.

In an advantageous embodiment of the household appliance, the device for detecting a flow rate of wash liquor, a power detection unit for detecting a power of at least one pump, wherein the means for detecting a flow rate of wash liquor is formed, the flow rate of wash liquor on the basis of the detected power of at least to determine a pump.

Thereby, the technical advantage is achieved that a determination of the flow rate of the wash liquor in the pumping system can be determined solely by the performance of the pump, without an additional component in the household appliance is needed. When the pump pumps the wash liquor at a high pumping rate, the wash liquor is moved at a high flow rate in the pumping system. Thus, the pumping power of the pump is directly related to the flow rate of wash liquor in the pumping system. Thereby, by means of the power detection unit, which detects the performance of a pump, a flow rate of wash liquor in the pumping system can be determined and the pump power optionally changed to cause a change in the flow velocity in the pumping system.

In an advantageous embodiment of the household appliance, the device for detecting a flow rate of wash liquor, a flow rate sensor, which is integrated into the first or second line. As a result, the technical advantage is achieved that a determination of the flow rate of the wash liquor can be performed precisely by a flow sensor located in one of the lines. The flow sensor also has the advantage that the flow velocity can be determined at a precisely defined point of the pumping system. This is particularly advantageous if no uniform flow velocity in the pumping system can be determined by projections or unevenness in the pumping system.

In an advantageous embodiment of the domestic appliance, at least one of the first and second pumps is designed to change the flow velocity or flow direction of wash liquor in the pump-over system.

Thereby, the technical advantage is achieved that a flexible regulation of the flow velocity or flow direction depending on the flow resistance, the amount of existing in the circulating pump liquor, or the amount of existing biofilm is possible. If biofilm deposits clog one of the lines in the pumping system, a change in the flow rate or a change in the flow direction of the wash liquor may be sufficient to remove the clogging.

In an advantageous embodiment of the household appliance, the first line and the second line open at the same point in the tub.

As a result, the technical advantage is achieved that the wash is splashed when entering the tub. The wash liquor is carried out at the same location from the tub into the first conduit and flows at the same location from the second conduit into the tub. Thus, the tub has a common discharge and inflow for wash liquor. Due to the different flow directions of the discharged and the incoming washing liquor in the tub to strong turbulence of the wash liquor. The turbulences lead to a splashing of the wash liquor in the tub. As a result, the wash liquor reaches a majority of the inner surface of the tub, so that an effective and effective removal of the biofilm is ensured. In an advantageous embodiment of the household appliance, the first line and the second line open at different locations in the tub.

As a result, the technical advantage is achieved that the flow rate of the wash liquor in the pumping system can be increased. Since the wash liquor flows out of the tub into the first conduit at one point and flows back into the tub at a different location from the second conduit, there is no strong swirling of the wash liquor upon entry into the tub. As a result, the flow rate of the wash liquor in the pumping system can be increased. Due to the rapid flow of the wash liquor in the pumping system, the wash liquor in the pumping system reaches a large part of the inner surface of the tub so that an effective and effective removal of the biofilm is ensured.

In an advantageous embodiment of the household appliance, the tub comprises a rotatably mounted washing drum, which is designed to rotate at a rotational frequency of 2 revolutions per minute to 2500 revolutions per minute.

As a result, the technical advantage is achieved that a wash liquor located in the tub is effectively distributed by the rotational movement of the washing drum in the tub and thus reaches as large as possible of the inner surface of the tub. The washing drum is stored in the tub and is thus in direct contact with the wash. Thus, a sufficient wetting of the laundry can be ensured by the washing liquor located in the tub. Due to the high frequency of rotation of the washing drum, mechanical energy is transferred to the wash liquor in the tub, whereby an effective separation of the biofilm is ensured.

In an advantageous embodiment of the household appliance, the household appliance comprises a filter unit for filtering wash liquor. As a result, the technical advantage is achieved that a part of the biofilm is removed by the filter from the pumping system and the functioning of the pump is not affected by the dirt particles in the wash liquor. The filter unit may comprise a column filter, pore filter or any other filter system available to those skilled in the art. The filter unit can be integrated in the tub, the liquor storage, or in the first or second line. The filter unit may be formed so that the in the wash liquor existing dirt particles and resulting from the washing process particles are retained. In addition, a reduced number of dirt particles leads to a smaller amount of detergent components that bind to the dirt particles. This can reduce the amount of detergent used. By removing biofilm through the filter unit, an additional cleaning effect of the wash liquor can be achieved.

In an advantageous embodiment of the household appliance, the household appliance comprises a temperature detection device for detecting a temperature of wash liquor. This achieves the technical advantage that regulation of the wash liquor temperature by the temperature detection device can also increase the effectiveness of the detergent components present in the wash liquor. At a wash liquor temperature of greater than 40 ° C, the effect of certain detergent components is increased, or only caused, which in turn results in effective delamination of the biofilm from an interior surface of the pump-around system. The temperature detection device may be a common device in all technical devices for detecting water and liquid temperatures. The temperature sensing device may also include a component that regulates the temperature of the wash liquor in the pumping system.

In an advantageous embodiment of the household appliance, the household appliance comprises a detergent dosing system for dosing a quantity of washing liquor.

This achieves the technical advantage that the amount of detergent added can be precisely regulated to achieve sufficient washing success and to prevent the formation of a biofilm on an inner surface of the pumping system. In addition, an excessive addition of detergent is prevented, which prevents wastage of detergent and the resulting environmental impact. By means of the detergent dosing system it can be ensured that, in addition to the amount of detergent needed for the washing process, a sufficient amount of detergent for removing the biofilm from the pumping system is also present in the washing liquor. The detergent dosing system can detect the amount of detergent present in the wash liquor and, if the amount of detergent is too small, add further detergent to the wash liquor. The detergent dosing system can be any standard in washing devices for detecting Detergent components or a decisive for the detergent concentration size in liquid and for further addition of detergent.

According to a second aspect of the invention, the object is achieved by a method for removing a biofilm from an inner surface of the conduits, the tub and the liquor storage of a domestic appliance, wherein the household appliance a Umpumpsystem with a pump for pumping wash liquor from a tub via a first Line via a liquor storage by a second line in the tub, and a means for detecting a flow rate of wash liquor in the pumping system comprises.

Thereby, the technical advantage is achieved that a biofilm, which can form over time on an inner surface, can be removed by washing liquor. The detergent components in the detergent mean that the biofilm can be effectively detached from the inner surfaces of the pumped circulation system. As a result, a comparable cleaning effect can be achieved, as with a commercially available washing machine cleaner.

In an advantageous embodiment of the method, the pump moves the wash liquor at a flow rate of 0.5 m / s to 1, 0 m / s in the pumping system.

As a result, the technical advantage is achieved that effective removal of the biofilm is achieved by the high flow rate of the wash liquor.

The pumping capacity is thus increased according to an embodiment such that the increased pumping power causes a flow rate of the wash liquor in the pumping system in the above exemplary flow rate range of 0.5 m / s to 1, 0 m / s.

In an advantageous embodiment of the method, the wash liquor is prepared in a previous wash cycle of the household appliance.

This achieves the technical advantage that a wash liquor prepared in a previous wash cycle of the domestic appliance can be used to remove the biofilm on an inner surface of the pumped circulation system. Thus, the generated wash liquor can be reused for biofilm removal. This becomes the Removing the biofilm requires no additional detergent, resulting in a time and cost saving cleaning of an inner surface of the pumping system.

In an advantageous embodiment of the method, the wash liquor has a temperature between 40 ° C and 90 ° C.

As a result, the technical advantage is achieved that the effectiveness of the laundry detergent components present in the wash liquor can be increased by regulating the wash liquor temperature. At a wash liquor temperature of greater than 40 ° C, the detergent components have a higher efficacy than at 25 ° C, which in turn results in effective delamination of the biofilm from an interior surface of the pumped circulation system.

Embodiments of the invention are illustrated in the drawings and will be described in more detail below.

Show it:

Fig. 1 is a schematic view of a household appliance; Figure 2 is a schematic view of a pumping system with a tub and with a liquor storage.

Fig. 3 is a schematic view of a pumping system with a tub; and FIG. 4 shows a schematic view of a pump-around system with a tub and with a liquor store with filter element;

Fig. 1 shows a schematic view of a washing machine representative of a general household appliance 100. The household appliance 100 comprises a door 103 for loading the household appliance 100 with laundry. The household appliance 100 comprises a storage container 101, into which detergent or other liquid substances can be introduced.

Fig. 2 shows a view of a pumping system with a tub 107 and a liquor storage 109. A first line 105 connects the tub 107 with the Lye storage 109 and includes a first pump 1 13, which is integrated into the first line 105. The pump 1 13 pumps liquor from the tub 107 to the liquor storage 109. A second line 1 1 1 connects the liquor storage 109 with the tub 107 and includes a second pump 1 15, which is integrated into the second line 1 1 1. The second pump 15 pumps wash liquor from the liquor storage 109 to the tub 107. The wash liquor moved by the pump can remove a biofilm on an inner surface of the first and second conduits 105, 111, the tub 107, and the liquor storage 109.

The use of wash liquor produces an equally good cleaning effect by the removal of biofilm on an inner surface of the pumping system, such as washing machine cleaners commonly used.

So that the wash solution reaches the entire inner surface of the pumped circulation system as far as possible, a special hydraulic connection is necessary. The interconnection shown in Figure 2 allows pumping the wash liquor. The wash liquor is conveyed out of the tub 107 and returned to the tub 107 at another or at the same location. This allows an optimal distribution of the wash liquor in the tub 107, as it comes especially with heavy pumping and an associated high flow rate of the wash liquor to a strong splashing of the wash liquor. The flow rate may be detected by a means for detecting a flow rate of wash liquor. If necessary, the flow rate can be regulated with the pump. A high flow rate ensures that the wash liquor reaches a large part of the inner surface of the pumped circulation system. This effect can be supported by the fact that in the tub 107 a rotatably mounted washing drum is introduced. The rotation of the washing drum results in an even better distribution of the washing liquor in the tub 107. In addition, the increased mechanical energy of the washing liquor moved through the washing drum supports the detachment of the biofilm from the inner surface.

In a special cleaning cycle of the household appliance 100, the wash liquor may optionally be generated only for the cycle of cleaning the household appliance. For this purpose, the detergent is added by the user in the dispenser and mixed at the start of the cleaning cycle with water and rinsed the mixture into the tub 107. During the cleaning cycle, there is no laundry in the washing machine. In the tub 107, which may comprise a washing drum, the wash liquor may optionally be better mixed by rotating the washing drum. In addition, the wash liquor can be heated to enhance the cleaning effect. Since some of the components of the wash liquor begin to act only from certain temperatures, such as 40 ° C, an elevated temperature may assist the detachment of the biofilm from the inner surface. By circulating the wash liquor in the household appliance 100, a sufficient distribution of the wash liquor in the pumping system can be ensured.

In a further special cleaning cycle of the household appliance 100, a wash liquor already prepared in a previous wash cycle of the household appliance 100 can be used for the cycle of cleaning the household appliance 100. During the previous wash cycle of the household appliance 100 inevitably results in a wash, which is usually discarded after the wash cycle. By means of the hydraulic interconnections according to the invention, however, the wash liquor can be pumped around, so that effective cleaning of the pumped circulation system can be achieved with the active surfactants and other detergent components still present in the wash liquor. The surfactants and other detergent components present in the wash liquor can clean all wash-liquor-carrying parts, in particular the liquor container 107, the liquor store 109 and the first and second lines 105, 11. This special cleaning cycle can be done after each wash cycle. Alternatively, this cleaning cycle may be performed at certain intervals after selected wash cycles, or this cleaning cycle may be specifically selected by the user of the home appliance 100. Alternatively, the pumping system can also be switched off in order to allow the substances present in the wash liquor to act in a stationary manner in the tub 107.

The system for recirculating wash liquor for equipment cleaning can be combined with a detergent dosing system. This can be done for example by a detergent sensor. By means of the detergent sensor, it can be determined exactly how much detergent is still available in the wash liquor for cleaning the appliance after the washing process. If too little detergent is available in the wash liquor, can be automatically replenished if necessary, so that an optimal sequence of equipment cleaning program is guaranteed. The pumping system according to the invention can be used in addition to the use in washing machines as well for washer-dryers and dishwashers.

By cleaning the household appliance 100, a biofilm generated on an inner surface of the pumping system can be effectively removed, leaving the domestic appliance 100 in a sanitary condition. There are no additional detergents used, but only the detergent needed anyway for cleaning the device. This leads to a cost reduction and a simplification of the use and increases the acceptance for the consumer. If the wash liquor prepared for a previous wash is also used for the equipment cleaning operation, water and detergent can be saved to a considerable extent. As a result, a significant cost reduction can be achieved.

Fig. 3 is a comparative example and shows a view of a pumping system with a tub 107. A first line 105 leads out at one point from the tub 107 and opens at another point back into the tub 107. A first pump 1 13 is in the integrated first line 105 to pump wash liquor through the first line 105.

Fig. 4 shows a view of a pumping system with a tub 107 and a liquor storage 109 with an integrated filter unit. A first line 105 connects the tub 107 with the liquor storage 109 and includes a first pump 1 13, which is integrated into the first line 105. The pump 1 13 pumps washing liquor from the tub 107 to the liquor storage 109. A second conduit 1 1 1 connects the liquor storage 109 with the tub 107. The filter unit may comprise a sieve or a filter. As a result, coarser, or with the use of a filter even smaller dirt particles, can be removed from the wash liquor during pumping. Parts of the biofilm can also be removed by the filter unit. This can further support the effectiveness of equipment cleaning. By using a filter unit to separate dirt less detergent components are consumed because the detergent components do not attach to the dirt separated by the filter.

All of the features explained and shown in connection with individual embodiments of the invention may be provided in different combinations in the article according to the invention in order to simultaneously realize their advantageous effects. The scope of the present invention is given by the claims and is not limited by the features illustrated in the specification or shown in the figures.

LIST OF REFERENCE NUMBERS

100 home appliance

101 storage tank

103 door

105 First line

107 tubs

109 liquor storage

111 Second line

113 First pump 115 Second pump

Claims

A household appliance (100) comprising a pumping system comprising a first conduit (105), a second conduit (11), a tub (107) and a liquor storage (109), the first and second conduits (105, 1 1 1) connects the tub (107) to the liquor storage (109), characterized in that the pumping system comprises a pump (1 13) for pumping wash liquor to remove a biofilm on an inner surface of the first and second conduits (105, 1100) ) of the tub (107) and the liquor storage (109), wherein the household appliance (100) comprises means for detecting a flow rate of wash liquor in the pumping system.

2. Household appliance (100) according to claim 1, characterized in that the pump (1 13) in the first line (105) is integrated.

3. Household appliance (100) according to claim 1 or 2, characterized in that the

Umpumpsystem a second pump (1 15), which is integrated in the second line (1 1 1).

4. Household appliance (100) according to one of the preceding claims, characterized in that the means for detecting a flow rate of wash liquor, a first level sensor for detecting a first level of wash liquor in the tub (107), and a second level sensor for detecting a second Level of wash liquor in the liquor storage (109), wherein the means for detecting a flow rate of wash liquor is adapted to determine the flow rate of wash liquor based on a comparison between the first and the second level.

5. Domestic appliance (100) according to one of the preceding claims, characterized in that the device for detecting a flow rate of wash liquor, a power detection unit for detecting a power of at least one pump (1 13, 1 15), wherein the means for detecting a Flow rate of wash liquor is formed, the Determine the flow rate of wash liquor based on the detected power of at least one pump (1 13, 1 15).

6. Household appliance (100) according to any one of the preceding claims, characterized in that the means for detecting a flow rate of wash liquor comprises a flow rate sensor which is integrated in the first or second line (105, 1 1 1).

7. Household appliance (100) according to one of the preceding claims, characterized in that at least one of the pumps (1 13, 1 15) is adapted to change the flow velocity or the flow direction of wash liquor in the pumping system.

8. Household appliance (100) according to any one of the preceding claims, characterized in that the first line (105) and the second line (1 1 1) at the same location in the tub (107) open.

9. Household appliance (100) according to one of the preceding claims 1 to 7, characterized in that the first line (105) and the second line (1 1 1) at different locations in the tub (107) open.

10. Household appliance (100) according to any one of the preceding claims, characterized in that the tub (107) comprises a rotatably mounted washing drum, which is designed to rotate at a rotational frequency of 2 revolutions per minute to 2500 revolutions per minute.

1 1. Household appliance (100) according to any one of the preceding claims, characterized in that the household appliance (100) comprises a filter unit for filtering wash liquor.

12. Household appliance (100) according to any one of the preceding claims, characterized in that the household appliance (100) comprises a temperature detecting means for detecting a temperature of washing liquor.

13. Household appliance (100) according to one of the preceding claims, characterized in that the household appliance (100) comprises a detergent dosing system for dosing a quantity of washing liquor.

14. A method for removing a biofilm from an inner surface of the conduit (105, 1 1 1), the tub (107) and the liquor storage (109) of a household appliance (100), characterized in that the household appliance (100) a Umpumpsystem with a Pump (1 13) for pumping wash liquor from a tub (107) via a first line (105) via a liquor storage (109) through a second line (1 1 1) in the tub (1 13), and a means for detecting a flow rate of wash liquor in the pumping system.

15. The method according to claim 14, characterized in that the wash liquor was prepared in a previous wash cycle of the household appliance (100).