EP2557981B1 - Domestic appliance having a plasma generator and method for the operation thereof - Google Patents

Description

The invention relates to a domestic appliance in the form of a dishwasher, a tumble dryer, a washing machine or a washer-dryer with a plasma generator and a method for its operation. The domestic appliance comprises a container that is exposed to moisture during operation of the domestic appliance and tends to form a biofilm on one of its inner surfaces.

In household appliances, especially those in which it is relatively humid, there is a tendency to form so-called biofilms, ie moist deposits that contain bacteria, fungi or other microorganisms. In washing machines, which have a Einspülschale for the supply of laundry and other laundry treatment products, often biofilms that give rise to hygiene concerns by their color and / or due to odor. The formation of biofilms should therefore be avoided or at least reduced to the extent that hygienic requirements are met.

To avoid these problems, materials for a dispenser tray are sometimes biocidically finished. Without a regular mechanical cleaning of the surfaces, a biofilm nevertheless forms over time, as new germs can settle on already dead germs. Another method is the treatment of incoming water with silver ions, which kill germs. However, silver ions react with water constituents. In addition, microorganisms also get from the ambient air in the Einspülschale.

An addition of ozone into the incoming water can kill the microorganisms present in the dispenser. The outgassing ozone can be distributed in the Einspülschale. Since an ozone addition takes place only during a water intake, a relatively high ozone concentration in the water is necessary. However, the solubility of the ozone in the water is low, so that most of the ozone enters the dispenser shell in gaseous form. As the ozone limit in the air is very low, extensive safety precautions are necessary to avoid the risk of ozone depletion.

Moreover, in a dishwasher or in a laundry treatment appliance such as a washing machine or a tumble dryer, an aqueous liquid may be produced which is not disposed of or not disposed of immediately, so that there is also a danger of microorganisms forming and multiplying here. The aqueous liquid may e.g. be in a tumble accumulating condensate.

For surface treatment and in particular also for disinfecting surfaces, treatment with a plasma produced by a high voltage is known.

An atmospheric pressure plasma is a plasma that can be generated at about atmospheric pressure. It has the advantage of relying on a sophisticated vacuum technique, e.g. Pumps, chambers, etc. can be dispensed with. Such atmospheric pressure plasmas are used, for example, for the treatment of the surface of a substrate, for example for cleaning, activation, coating or any other modification. Atmospheric pressure plasmas can be placed in so-called cold, i. distinguish non-thermal plasmas having a gas temperature of typically less than 100 ° C and thermal plasmas having a higher gas temperature. Cold plasmas have the advantage that the temperature of the gas is approximately at room temperature or slightly above, so that a plasma may also be allowed to act on a substrate for a longer time without damaging the substrate and in particular its surface.

That's how it describes US 5,637,279 A a nonthermal atmospheric pressure plasma with dielectrically impeded discharges in which there is a dielectric barrier between the electrodes. Plasmas produced in this way are already used for the production of ozone for the purpose of purifying water or for surface modification of plastic films.

Plasma generators for producing a plasma of this kind are also in the documents DE 10 2005 032 890 B4 . DE 10 2008 018 827 A1 and EP 2 141 968 A2 described.

Domestic appliances with a plasma generator are also off CN 2 564 608 Y . JP 2004 085877 A . EP 1 469 119 A1 and KR 2007 0066334 A known. It concerns CN 2 564 606 Y and EP 1 469 119 A1 Washing machines in which the plasma is generated in the washing water, to effect a cleaning of the laundry or improve. For a tumble dryer according to KR 2007 0066334 A the plasma generator is arranged in a passage of the air duct, wherein the inflowing air is sterilized with the plasma generator to sterilize the laundry. The household appliance according to JP 2004 065877 A is a dishwasher in which the plasma generator for sterilizing the dishwasher or for removing bacteria is arranged.

Against this background, it is an object of the present invention, a household appliance in the form of a dishwasher, a tumble dryer, a washing machine or a Waschtrockners provide, which has an improved control of microorganisms and offers the possibility of avoiding or largely eliminating biofilms.

The object underlying the invention is achieved by a domestic appliance and a method for their operation according to respective independent claim. Preferred embodiments of the invention are listed in the respective dependent claims. Preferred embodiments of the domestic appliance according to the invention correspond to preferred embodiments of the method according to the invention, even if it is not separately pointed out here.

The invention thus relates to a domestic appliance in the form of a dishwasher, a tumble dryer, a washing machine or a washer dryer with a container which is exposed to moisture during operation of the domestic appliance and tends to form a biofilm on one of its inner surfaces, and at least one plasma generator the plasma generator can generate a cold atmospheric pressure plasma and is spaced less than 5 cm, preferably less than 2 cm, from the biofilm-tending inner surface of the container. The plasma generator may be disposed on a surface opposite to the inner surface tending to form a biofilm. The particular advantage of such an arrangement is that the plasma is generated directly at the location where a biofilm is to be eliminated. Thus, air molecules are ionized in the immediate vicinity of the surface to be cleaned. For example, during operation of the plasma generator, ozone, nitrogen oxides, hydrogen peroxide, free radicals and UV light are generated.

Since the plasma generated due to the inventive arrangement of the plasma generator or the plasma generators can already act in their immediate environment, it is generally unnecessary to discharge the generated reactive, biocidal particles. The passage of an air flow on the plasma generator, possibly generated by a fan, therefore unnecessary.

Preferably, the plasma generator or the plasma generators are formed flat. Alternatively, several plasma generators can be side by side on one surface be arranged. Thus, it is possible to provide a continuous biocidal atmosphere over a larger area, which can cause biofilm degradation on a surface located in that area.

In a preferred embodiment of the domestic appliance, the plasma generator is arranged in an induction dish or a tub of a washing machine or a washer-dryer.

In a further preferred embodiment of the domestic appliance, the plasma generator is arranged in a storage container for an aqueous liquid.

In this case, the storage container may in particular be a condensate collecting container, a soft water container, a hard water container and / or a flushing water storage.

The storage container is preferably in the case of a tumble dryer or washer dryer, a condensate collection container for condensate incurred in the drying of moist air condensate. The condensate collecting container may in this case be a condensate tray arranged below a heat exchanger and / or a condensate storage container, in which the condensate collected in the condensate tray can be transferred, for example, by pumping off.

In the case of a dishwasher, a washing machine or a washer-dryer, the storage container is preferably a rinse water storage.

In a particularly preferred embodiment of the invention, the domestic appliance is therefore a washing machine with a tub, a laundry drum, a water supply system and a lye drain system with a drain pump, a program control and a rinse water storage, and a plasma generator described herein, at a distance of less than 5 cm is arranged from an inner surface of the container.

In a preferred embodiment, in which the domestic appliance is a washing machine, this washing machine preferably also has a desalting device for producing demineralized water, for example a reverse osmosis device, During their operation desalinated water (soft water) and salted water (hard water) incurred.

The invention is therefore particularly suitable for a household appliance with a soft water tank and / or a hard water tank. The soft water container is preferably connected to the water supply system via a desalination device.

In a rinse water storage used rinse water is cached in a washing machine or a dishwasher, to be used for example in a subsequent wash cycle. Especially the used water from the last rinses in a washing machine is so clean that it can easily be used instead of fresh water for the wetting and washing of laundry. In addition, desalted, used rinse water already has the advantage that the detergent concentration does not have to be adjusted with respect to the degree of hardness, since the desalted water is already "soft", even if it has undergone a rinse cycle. Thus, used desalted rinse water is even more advantageous as wash water than fresh water.

Microorganisms can occur in the soft water container, hard water container and / or rinse water storage and, in particular, biofilms can also form, so that attachment of the plasma generators described herein is very advantageous.

The plasma generator, as long as it can generate a cold atmospheric pressure plasma, according to the invention is not limited. In addition, the term plasma generator as used herein includes one or more plasma generators.

In a preferred embodiment, the plasma generator comprises a piezoceramic element, on which a cold atmospheric pressure plasma can be generated. Suitable plasma generators of this type are in any of the already mentioned documents DE 10 2005 032 890 B4 . DE 10 2008 018 827 A1 and EP 2 141 968 A2 described.

Preferably, in the plasma generator of this embodiment, the piezoceramic element comprises a primary region and a secondary region, wherein the Primary region has electrodes to which an AC voltage is applied and thereby electric fields are generated in the secondary region, so that a gas in the vicinity of the secondary region, in particular air, is converted into a plasma.

In a further preferred embodiment of the domestic appliance, the plasma generator comprises a first electrode, a dielectric and a second electrode. In this case, the dielectric preferably comprises a plastic. More preferably, the dielectric is made of a plastic. Suitable plastics are, for example, fluorinated polyethylenes or polypropylenes. In particular, polytetrafluoroethylene (PTFE) is suitable.

The second electrode is preferably designed as a metallic network, wherein a plasma is formed during operation of the plasma generator generally in the mesh of the network.

In a preferred embodiment of the domestic appliance according to the invention, the first and / or second electrode contains copper or consists of copper.

The plasma generator used in the domestic appliance according to the invention can be small. In addition, the energy requirement is generally low. Thus, the mains supply of the domestic appliance or of a rechargeable battery, for example a 12 V rechargeable battery, can frequently be used as voltage supply to the plasma generator. The domestic appliance may additionally have means for transforming the mains supply voltage or the accumulator voltage to the operating voltage of the plasma generator. The use of an accumulator allows use of the plasma generator even during downtime of the domestic appliance. A standstill time is understood to mean in particular the time in which the household appliance is at rest, out of operation or not in the state of intended use.

The plasma generated by the plasma generator generally contains a complex mixture of reactive, biocidally active particles, which in particular also comprise oxygen radicals. For example, the strong electric field at an electric voltage in the range of 17 to 20 kV between a first electrode of copper and a present as a wire mesh second electrode between which causes Dielectric of polytetrafluoroethylene is arranged, numerous discharges of generally only a duration of micro- and nanoseconds, which ionize some of the air molecules.

The domestic appliance in embodiments enables the automatic removal of microorganisms and in particular biofilm within the domestic appliance. A special information about this for a user of the household appliance is not necessary.

However, the home appliance may also include a display device that indicates the operation of a plasma generator. The display device may be an optical and / or acoustic display device.

In a domestic appliance according to the invention, e.g. a washing machine, there is generally a control device which, in addition to the control of a cleaning program, can also carry out the control of the plasma generators in relation to the beginning and duration of a plasma generation. In general, the plasma generators are operated when no water is passed by them. During operation of the plasma generator, the control device can effect a corresponding acoustic and / or optical display on the display device.

If the household appliance according to the invention is a washing machine, preferably a pressure sensor and / or a temperature sensor are arranged in the tub of the latter. Pressure and temperature sensor, if present, are preferably arranged in a lower region of the tub, so that pressure and / or temperature of an aqueous liquid present in the tub can be measured.

The invention also relates to a method for operating a domestic appliance in the form of a dishwasher, a tumble dryer, a washing machine or a washer dryer with a container which is exposed to moisture during operation of the domestic appliance and tends to form a biofilm on one of its inner surfaces, and at least a plasma generator which can generate a cold atmospheric pressure plasma and at a distance of less than 5 cm, preferably less than 2 cm, from the biofilm-tending inner surface of the biofilm In which method the plasma generator produces a cold atmospheric pressure plasma which biocides on the biofilm-tending inner surface of the container, the generation of the plasma and the action on the inner surface (29), while the the surface surrounding air rests. That is, in the method according to the invention, the plasma generation takes place directly at the place where the biofilm is to be eliminated, and means for generating an air flow or a flow of the medium surrounding the surface to distribute the plasma or to transport to the surface to be cleaned , are not provided. In general, no aqueous liquid is introduced into the container during the practice of this process.

In a preferred embodiment of this method is displayed on a display device when a plasma is generated in the context of the method according to the invention.

The invention has the advantage that microorganisms in a household appliance can be controlled in a simple and very efficient manner, and in particular the formation of a biofilm can be avoided or reduced. This causes color changes and odors can be avoided or eliminated. Overall, an improvement in hygiene is achieved.

• Figur 1 ist eine schematische Darstellung einer frontalen Schnittansicht einer ersten Ausführungsform eines Hausgerätes, hier als Waschmaschine ausgestaltet, die einen Weichwasserbehälter, einen Speicherbehälter für aufgesalzenes Wasser ("Hartwasserbehälter") und einen Behälter für Spülwasser ("Spülwasserspeicher") aufweist, die jeweils einen Plasmagenerator aufweisen.
• Figur 2 ist eine vergrößerte Darstellung einer Einspülschale mit einem Plasmagenerator gemäß einer zweiten Ausführungsform eines Hausgerätes, das hier ebenfalls als Waschmaschine ausgestaltet ist.

Embodiments of the invention, in which the domestic appliance is a washing machine, are described below with reference to FIG FIGS. 1 and 2 illustrated.

• FIG. 1 is a schematic representation of a frontal sectional view of a first embodiment of a household appliance, here designed as a washing machine having a soft water tank, a storage container for saline water ("hard water tank") and a container for rinse water ("rinse water storage"), each having a plasma generator.
• FIG. 2 is an enlarged view of a Einspülschale with a plasma generator according to a second embodiment of a household appliance, which is also designed here as a washing machine.

In the schematic representation of FIG. 1 are the presently relevant parts of a washing machine, in which a method to be explained below, can be performed. Other embodiments are conceivable. The washing machine has a tub 4 in which a laundry drum 2 with laundry 7 located therein can be rotatably mounted and operated by a drive motor 14. Particularly shaped Wäschemitnehmer 34 and scooping devices 5 for the wash liquor 6 contribute to an intensification of the flooding of the laundry 7 with wash liquor 6 or 6 with rinse water. The washing machine has a liquor inlet system comprising a water connection for the domestic water network 8, an electrically controllable valve 9, a water inlet 33 and a supply line 10 to the tub 4, which is guided via a dispenser 11, from which the feed water (fresh water) treatment agent in can transport the tub 4. In the tub 4 is a heater 13. The valve 9 as well as the heater 13 can be controlled by the program control 12 in response to a program flowchart. A pressure sensor 15 is provided for the measurement of the hydrostatic pressure p in the tub 4.

There is provided a reverse osmosis device as desalting device 17 for the desalination of water, which is arranged between the inlet valve 9 and the tub 4, in particular between the valve 9 and a soft water tank 24 or hard water tank 18, but via a line to the dispenser 11 is connected to the tub 4 over. At the in Fig. 1 As shown in the first embodiment, the reverse osmosis results in a partially desalinated water (referred to herein as "soft water") which is collected in a soft water tank 24. For this purpose, the desalting device 17 is connected to the soft water tank 24 via a first soft water line 25. The soft water tank 24 is in turn connected via a second soft water line 27 with the tub 4, so that desalted water (soft water) can be added as desired in the tub 4 and thus in the laundry drum 2. Between the desalting device 17 and the soft water tank 24, there is a conductivity sensor 19 as a first sensor for detecting a salinity of the water passed through the desalting device 17. In addition, in this embodiment, a storage vessel 18 connected to the desalting device 17 via a saline water pipe 26 is for water having a higher salt concentration (Hard water tank 18) provided. Since the desalting device 17 used in this embodiment is a reverse osmosis device, the saline water resulting from the desalting is collected and stored for later use, eg, for initial rinses.

In addition, in the illustrated embodiment, a rinse water storage 22 is provided, which can store the water used in rinsing the laundry. This water (so-called "rinse water"), especially if it is the previously desalted and then used in rinsing water, can be used for a later wash. For this purpose, the rinse water storage 22 is connected via a line 23 ("first supply line for salted-up water") with the valve 9, which also controls the supply of fresh water. 16 denotes a pump for conveying the rinse water into the rinse water storage 22.

In the soft water tank 24, in the rinse water storage 22, in the hard water tank 18, in the dispenser 11 and in the tub 4 each have a plasma generator 3 for generating a cold atmospheric pressure plasma is arranged in air (the plasma generator 3 in the tub 4 is not shown for clarity) so that no microorganisms can form or spread due to the storage of these aqueous liquids over possibly several days or due to the moist air in conjunction with organic compounds such as detergents and fabric softeners. The plasma generators 3 are each located at a distance of 0.5 to 1.5 cm to an inner surface 29 of the aforementioned container or the dispenser. In this embodiment, the plasma generator does not include in detail here a first electrode made of copper, a dielectric made of polytetrafluoroethylene and a second electrode made of copper.

In the lower region of the tub 4 is a second conductivity sensor 20, with which the content of the rinsing water to inorganic and organic substances can be determined after rinsing. For this purpose, data stored in a memory of the program control 12 can be used for the relationship between the type and concentration of the salts or inorganic and organic substances and the conductivity.

For the acoustic and / or visual display of a plasma generation taking place, a display device 21 is located on the washing machine 1 of the specific embodiment shown here. The plasma generators 3 are operated in this embodiment if no water supply into the containers takes place.

FIG. 2 is an enlarged view of a Einspülschale 11 with multiple plasma generators 3 according to a second embodiment of a domestic appliance according to the invention, which is also designed here as a washing machine. In this case, the plasma generators comprise a piezoceramic element or a first electrode, a dielectric and a second electrode-here not shown in detail. Here, the plasma generators 3 are each about 5 to 10 mm away from an inner surface 29 of the dispenser shell 11, so that the formation of a biofilm can be effectively suppressed thereon. About a water inlet 33 and a plurality of openings (shower) 32 water from a water supply, not shown here enters the dispenser 11 and from this via a supply line 10 in a not shown here of the washing machine. When using the invention in an induction dish is particularly advantageous that the plasma generators 3 can be arranged in a relatively small space, so that, for example, the wall with the plurality of openings 32 in the biocidal atmosphere generated by the plasma generators 3 and a There deposited biofilm can be eliminated. That is, in such embodiment, the distance wall with the plurality of openings 32 is also only about 10 mm away from the plasma generators 3. The plasma generators are operated when no water supply occurs.

LIST OF REFERENCE NUMBERS

1

household appliance

2

washing drum

3

plasma generator

4

tub

5

scooping devices

6

suds

7

Laundry

8th

Domestic water supply

9

Valve

10

supply

11

dispenser tray

12

program control

13

heater

14

drive motor

15

pressure sensor

16

pump

17

desalter

18

Storage tank for salted up water, hard water tank

19

first conductivity sensor

20

second conductivity sensor

21

display

22

backwash water

23

first supply line for salted water or rinse water

24

Soft water tank

25

first soft water line

26

first line for salted water

27

second soft water line

28

second line for salted water

29

an inner surface of a container

30

Rotary axis of the drum

31

Einspülschalengehäuse

32

shower

33

water supply

34

laundry agitator

Claims (15)

1. Domestic appliance (1) in the form of a dishwasher, a laundry drier, a washing machine or a washer-drier, with a container (4, 11, 18, 22, 24), which is exposed to moisture during operation of the domestic appliance and has an inner surface (29) to be cleaned from a biofilm, and a plasma generator (3) which is constructed for generating a cold atmospheric-pressure plasma, i.e. a non-thermal plasma, which is produced at atmospheric pressure, with a gas temperature less than 100° C, characterised in that the plasma generator (3) is arranged at a spacing of less than 5 centimetres from the inner surface (29), which is to be cleaned from the biofilm, of the container (4, 11, 17, 22, 24) so that generation of the plasma and action on the inner surface can take place while the air surrounding the surface is at rest.
2. Domestic appliance (1) according to claim 1, wherein the plasma generator is of flat construction or several of the plasma generators are arranged adjacent to one another on a surface.
3. Domestic appliance (1) according to claim 2, characterised in that the plasma generator (3) is arranged in a flushing-in tray (11) or a solution container (4) of a washing machine (1) or a washer-drier.
4. Domestic appliance (1) according to any one of claims 1 to 3, characterised in that the plasma generator (3) is arranged in a storage container (18, 22, 24) for an aqueous liquid.
5. Domestic appliance (1) according to claim 4, characterised in that the storage container (18, 22, 24) is a condensate collecting container, a container (24) constructed for receiving soft water, a container (18) for receiving hard water and/or a flushing water reservoir (22).
6. Domestic appliance (1) according to any one of claims 1 to 5, characterised in that the plasma generator 93) comprises a piezo-ceramic element at which a cold atmospheric-pressure plasma can be generated.
7. Domestic appliance (1) according to claim 6, characterised in that the piezo-ceramic element has a primary region and a secondary region, wherein the primary region comprises electrodes to which an alternating voltage is applied and electric fields are thereby generated in the secondary region so that a gas in the environment of the secondary region is converted into a plasma.
8. Domestic appliance (1) according to any one of claims 1 to 5, characterised in that the plasma generator (3) comprises a first electrode, a dielectric and a second electrode.
9. Domestic appliance (1) according to claim 8, characterised in that the dielectric comprises a plastic material.
10. Domestic appliance (1) according to claim 8 or 9, characterised in that the second electrode is constructed as a metallic mesh.
11. Domestic appliance (1) according to any one of claims 8 to 10, characterised in that the first and/or second electrode contains copper or consists of copper.
12. Domestic appliance (1) according to any one of claims 1 to 11, characterised in that the domestic appliance (1) comprises accumulators for voltage supply of the plasma generator (3).
13. Method of operating a domestic appliance (1) in the form of a dishwasher, a laundry drier, a washing machine or a washer-drier, with a container (4, 11, 18, 22, 24) which in operation of the domestic appliance is exposed to moisture and has an inner surface (29) to be cleaned from a biofilm, and a plasma generator (3) by which in the method a cold atmospheric-pressure plasma is generated, i.e. a non-thermal plasma, which is generated at atmospheric pressure, with a gas temperature less than 100° C, characterised in that the plasma generator (3) is arranged at a spacing of less than 5 centimetres from the inner surface (29), which is to be cleaned from the biofilm, of the container (4, 11, 18, 22, 24) and that the cold atmospheric-pressure plasma generated by the plasma generator (3) has biocidal action on the inner surface (29), which is to be cleaned from the biofilm, of the container (4, 11, 18, 22, 24), wherein the generation of the plasma and the action on the inner surface (29) take place while the air surrounding the surface is at rest.
14. Method according to claim 13, characterised in that the plasma generation takes place only when no aqueous liquid is conducted into the container (4, 11, 18, 22, 24).
15. Method according to claim 13 or 14, characterised in that the plasma generation takes place only when the domestic appliance (1) is not in operation.

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