WO2011141263A1 - Domestic appliance having a plasma generator and method for the operation thereof - Google Patents

Abstract

The invention relates to a domestic appliance (1) having a container (4, 11, 18, 22, 24) which, during operation of the domestic appliance, is subjected to moisture and tends to form a biofilm on one of the inner surfaces (29) thereof, and having a plasma generator (3), wherein the plasma generator (3) can generate a cold atmospheric pressure plasma and is arranged at a distance of less than 5 cm from an inner surface (29) of the container (4, 11, 18, 22, 24). The invention further relates to a method for operating said domestic appliance.

Description

 Domestic appliance with plasma generator and method for its operation

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 health hazards due to escaping ozone. 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 risk of formation and multiplication of microorganisms. The aqueous liquid may be condensate accumulating in a tumble dryer, for example.

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.

Thus, US Pat. No. 5,637,279 A describes a non-thermal atmospheric pressure plasma with dielectrically impeded discharges in which a dielectric barrier exists 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 type are also described in the documents DE 10 2005 032 890 B4, DE 10 2008 018 827 A1 and EP 2 141 968 A2.

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 located at a distance of 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 flushing 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, so used desalted rinse water as wash water is even more advantageous 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 described in each of the already mentioned documents DE 10 2005 032 890 B4, DE 10 2008 018 827 A1 and EP 2 141 968 A2.

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.

Exemplary embodiments of the invention in which the domestic appliance is a washing machine are illustrated below with reference to FIGS. 1 and 2. Figure 1 is a schematic representation of a frontal sectional view of a first embodiment of a domestic 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 exhibit.

FIG. 2 is an enlarged view of an induction bowl with a plasma generator according to a second embodiment of a household appliance, which is likewise designed here as a washing machine. The schematic representation of FIG. 1 shows the relevant parts of a washing machine in which a method to be explained below can be carried out. 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, which comprises 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 an induction dish 1 1, from which the feed water (fresh water) treatment agent can transport in 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 1 1 is connected to the tub 4. In the first embodiment shown in Figure 1, reverse osmosis results in a partially desalted water (herein called "soft water") being 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 to the suds container 4 via a second soft water line 27, so that desalted water (soft water) can be added as desired to the suds container 4 and thus to the laundry drum 2. Between the desalination device 17 and the soft water container 24 there is a conductivity sensor 19 as the first sensor for detecting a salinity of the water passed through the desalting device 17. In this embodiment, in addition, a storage vessel 18 connected to the desalting device 17 through a saline water line 26 is provided with water of higher Sa. lzkonzentration (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 "rinsing water") can be used for a later washing cycle, in particular if it is the previously desalinated and then used during rinsing, for which purpose the rinse-water storage 22 is connected via a line 23 ("first supply line for salted-up water ") connected to the valve 9, which also controls the fresh water supply. 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 tank 22, in the hard water tank 18, in the dispenser 1 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 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, when no water supply occurs in the container.

Figure 2 is an enlarged view of a dispenser 1 1 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 1, so that on this effectively the formation of a biofilm can be suppressed. Via a water inlet 33 and a plurality of openings (shower) 32 water from a water supply, not shown here enters the dispenser 1 1 and from this via a supply line 10 in a not shown here, 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 laundry drum

 3 plasma generator

 4 tubs

 5 scooping devices

 6 wash liquor

 7 laundry

 8 domestic water network

 9 valve

 10 supply line

 1 1 dispenser tray

 12 program control

 13 heating device

 14 drive motor

 15 pressure sensor

 16 pump

 17 desalting device

 18 storage tanks for salted water, hard water tank

19 first conductivity sensor

 20 second conductivity sensor

 21 display device

 22 rinse water storage

 23 first supply line for salted-up water or rinse water

24 soft water tanks

 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 axis of rotation of the drum

31 Induction bowl housing shower

 water supply

laundry agitator

Claims

1. domestic appliance (1) in the form of a dishwasher, a tumble dryer, a washing machine or a washer dryer with a container (4, 1 1, 18,22,24), which is exposed to moisture during operation of the household appliance and to form a biofilm on a its inner surfaces (29), and a plasma generator (3), characterized in that the plasma generator (3) is designed to generate a cold atmospheric pressure plasma and at a distance of less than 5 cm from the tendency to biofilm forming inner Surface (29) of the container (4, 1 1, 18,22,24) is arranged. 2. domestic appliance (1) according to claim 1, wherein the plasma generator is formed flat or more of the plasma generators are arranged side by side on a surface. 3. domestic appliance (1) according to claim 2, characterized in that the plasma generator (3) in a dispensing dish (1 1) or a tub (4) a washing machine (1) or a washer dryer is arranged. 4. domestic appliance (1) according to one of claims 1 to 3, characterized in that the plasma generator (3) in a storage container (18, 22, 24) is arranged for an aqueous liquid. 5. domestic appliance (1) according to claim 4, characterized in that the storage container (18, 22, 24) is a condensate collecting container, a soft water tank (24), a hard water tank (18) and / or a flushing water storage (22). 6. domestic appliance (1) according to one of claims 1 to 5, characterized in that the plasma generator (3) comprises a piezoceramic element, on which a cold atmospheric pressure plasma can be generated. 7. domestic appliance (1) according to claim 6, characterized in that the piezoceramic element comprises a primary region and a secondary region, wherein the primary region comprises electrodes to which an AC voltage is applied and thereby electric fields are generated in the secondary region, so that a gas in the Surrounding the secondary area is converted into a plasma. 8. domestic appliance (1) according to one of claims 1 to 5, characterized in that the plasma generator (3) comprises a first electrode, a dielectric and a second electrode. 9. domestic appliance (1) according to claim 8, characterized in that the dielectric comprises a plastic. 10. domestic appliance (1) according to claim 8 or 9, characterized in that the second electrode is formed as a metallic mesh. 1 1. domestic appliance (1) according to one of claims 8 to 10, characterized in that the first and / or second electrode contains copper or consists of copper. 12. domestic appliance (1) according to one of claims 1 to 1 1, characterized in that the domestic appliance (1) has accumulator for supplying power to the plasma generator (3). 13. A method for operating a domestic appliance (1) in the form of a dishwasher, a tumble dryer, a washing machine or a washer dryer with a container (4, 1 1, 18,22,24), which is exposed to moisture during operation of the domestic appliance and training a biofilm on one of its interior surfaces (29), and a plasma generator (3) capable of producing a cold atmospheric pressure plasma and less than 5 cm from the biofilm-tending interior surface (29) of the container (4, 1 1, 18, 22, 24), in which method the plasma generator (3) generates a cold atmospheric pressure plasma which biocides on the biofilm-tending inner surface (29) of the biofilm Container (4, 1 1, 18,22,24) acts, wherein the generation of the plasma and the action on the inner surface (29) takes place while the air surrounding the surface rests. A method according to claim 13, characterized in that the plasma generation takes place when no aqueous liquid in the container (4, 1 1, 18, 22, 24) is introduced. 15. The method according to claim 13 or 14, characterized in that the plasma generation takes place when the domestic appliance (1) is put out of operation.