EP2390398A1 - Domestic appliance with water treatment device for treating stored process water - Google Patents

Abstract

The appliance has a tub (1) for cleaning goods e.g. dishes and clothes, to be cleaned, and a tank (2) for intermediate storage of process water that is discharged from the tub. A controller (3) is designed to convey the water from the tub into the tank and to transports the water from the tank return to the tub in a separate cleaning step. A water treatment device (9) has an electrolysis cell comprising a diamond electrode for treating the water to be stored in the tank. The controller is designed to treat the water before and/or during its storage in the tank by the water treatment device.

Description

Field of the invention

The invention relates to a household appliance, in particular a dishwasher or a washing machine. The domestic appliance has a tub for cleaning a material to be cleaned, a tank for temporarily storing process water discharged from the tub, and a controller. The controller is designed to pump process water from the tub into the tank and to pump the process water from the tank back to the tub in a later cleaning cycle with new material to be cleaned.

background

WO 2005/051157 describes a dishwasher with a tank to store a portion of the process water between two washes. To clean the water in the tank, a biological water treatment device is provided. In order to make the thereby acting microorganisms ineffective, it is further proposed to treat the process water with UV light, ozone or the like.

EP 909 848 describes a washing machine, which is also equipped with a tank for intermediate storage of process water between two washes.

The water in the tank of such devices is contaminated with impurities. Prolonged storage time leads to uncontrolled germ growth, be it due to controlled cleaning bacteria, or due to other, accidentally introduced germs. This will affect the water quality. Therefore the permissible storage time of the water is comparatively short.

Presentation of the invention

It has as its object to provide a household appliance of the type described above, in which the process water in the tank can be stored in a simple and reliable manner for a relatively long time.

This object is achieved by the device according to claim 1. Accordingly, the device is thus equipped with a water treatment device comprising an electrolytic cell with at least one diamond electrode for treating the process water to be stored in the tank. The control of the device is designed to treat the process water before and / or during storage in the tank with the water treatment device. It has been found that the use of a diamond electrode in the water treatment device in this context brings important benefits by forming highly active molecules (ozone, hydrogen peroxide, hydroxyl radicals,...) That kill bacteria and degrade contaminants without in significant quantities dangerous hydrogen is produced.

The water treatment device may, for example, be arranged at the path of the process water between the tub and the tank and / or at the tank and / or at a circulation line arranged on the tank so that it can be connected to the process water.

In a preferred embodiment, a tank circulation line is provided on the tank to guide the process water from the tank through the circulation line back to the tank. In this case, the water treatment device is arranged on the tank circulation line, so that the process water to be stored can be treated while circulating.

In a further embodiment, however, the water treatment device can also be arranged on a tub circulation line.

The household appliance may further be equipped with a Dektetor for detecting the radical concentration of the process water. In particular, a detector for measuring the redox potential of the process water is suitable for this purpose. This makes it possible to control the water treatment device depending on the signal of this detector.

The water treatment device can be used not only for processing the process water to be stored, but also additionally for treating the process water during the cleaning cycle. This can assist the cleaning process.

Preferably, the household appliance is a dishwasher or a washing machine.

Brief description of the drawings

• Fig. 1 ein Blockdiagramm einer ersten Ausführung eines Haushaltsgeräts,
• Fig. 2 ein Blockdiagramm einer zweiten Ausführung eines Haushaltsgeräts und
• Fig. 3 das Redox-Potential bei Behandlung von sauberem und verschmutztem Wasser.

Further embodiments, advantages and applications of the invention will become apparent from the dependent claims and from the following description with reference to FIGS. Showing:

• Fig. 1 a block diagram of a first embodiment of a household appliance,
• Fig. 2 a block diagram of a second embodiment of a household appliance and
• Fig. 3 the redox potential when treating clean and polluted water.

Ways to carry out the invention

In Fig. 1 schematically a household appliance is shown with a tub 1 for cleaning a Guts to be cleaned. This may be, for example, the tub of a washing machine or a dishwasher, in which the laundry or dishes during cleaning is arranged. The device is designed to clean the material to be cleaned in a cleaning cycle. Typically, such a cleaning cycle has several phases, such as a main wash phase, in which using chemical washing reagents most of the dirt is removed from the estate, and at least one rinsing phase (in dishwashers often referred to as rinse phase), in which in the main wash phase already substantially cleaned good is still rinsed. Between these phases, the process water is replaced at least for the most part.

The device is now equipped in a conventional manner with a tank 2 to store process water from a cleaning cycle and returned in a later cleaning cycle back to the tub to reduce in this way the water consumption of the device. Preferably, but not necessarily, the process water is transferred at the end of the rinsing phase in the tank 2, since this water has a relatively low pollution and therefore is particularly well suited for storage and reuse. The process water from the tank 2 is then fed back to the tub 1 in a subsequent wash cycle, in particular the next wash cycle. The recycled process water is preferably used for the main wash phase or one of the main wash phase preceded pre-wash phase.

The processes required for this purpose are controlled by a controller 3 of the device. The controller 3 includes, for example, a microprocessor with a control program that performs the above steps automatically. It is also conceivable, however, the design of the controller in a purely mechanical manner. The controller 3 is connected to the actuators and Detectors connected to the device, as well as with a control and display unit, not shown. In the following, when it is said that the controller or device is configured to perform certain steps, it should be understood that the controller is programmed or mechanically configured and connected to the components of the device to perform these steps.

How out Fig. 1 it can be seen, a tub circulation line 4 is provided at the tub 1, with which process water from the tub 1 via a tub circulation pump 5 and a water diverter 6 can be performed. Depending on the setting of the water switch 6, the process water from the tub circulation pump 5 can optionally be conveyed back to the tub 1 or to the tank 2. (Alternatively, a separate pump may be provided to direct the water from the tub 1 into the tank 2, eg, before the valve 10 described below.) In the circulation line 4, a turbidity sensor 15 is further provided, with which the contamination state of the process water can be detected.

How farther Fig. 1 can be seen, a tank circulation line 7 is provided on the tank 2, with which process water from the tank 2 via a tank circulation pump 8 and a water treatment device 9 can be guided back into the tank 2.

In the execution after Fig. 1 The process water coming from the tub 1 via the tank circulation pump 5 and the water switch 6 flows through the water treatment device 9 before it reaches the tank 2, so that it can already be treated on its way to the tank 2.

Furthermore, the device comprises according to Fig. 1 a valve 10 which connects the drain of the tank 2 with the tub 1. If this valve 10 is opened, then The water flows from the tank 2 due to its gravity in the tub 1.

The water treatment device 9 comprises an electrolysis cell with two electrodes, at least one of which is formed by a diamond electrode. A diamond electrode is to be understood as meaning an electrode whose surface is formed by diamond rendered conductive by doping. Preferably, the diamond is doped with boron, but other dopants may be used. Such electrodes are e.g. prepared by depositing from the gases methane and hydrogen at 2500 ° C a thin crystalline diamond layer only a few thousandths of a millimeter thick on a conductive support material (e.g., titanium). The doping can be done later or during the gas phase deposition.

At least the anode should be formed by a diamond electrode, so that the generation of hydrogen is suppressed. The cathode may also be formed by a diamond electrode, but other electrode materials, such as e.g. Stainless steel. Preferably, however, both electrodes are formed by diamond electrodes. In this case, the device can be designed so that a voltage of alternating sign is applied over the two electrodes, whereby deposits on the electrodes can be avoided.

Furthermore, the device is equipped with a redox detector 11, which allows to measure the redox potential of the process water in the tank circulation line 7 or in the tank 2. Detectors of this type are known in the art.

As a further sensor, a quality sensor 12 is provided to measure the quality of the process water in the tank 2. This is preferably a gas sensor which is arranged in an upper, not filled with process water part of the tank 2, and in the It is able to detect gases escaping from the water, which indicate a bacterial metabolism, in particular an anaerobic bacterial metabolism, such as methane, but also other organic gases or ammonia or hydrogen sulfide. Sensors of this type are also known to the person skilled in the art. For example, the sensors TGS 2602 or TGS 842 from Figaro USA Inc., Arlington Heights, can be used.

The function of the device after Fig. 1 will now be described in detail.

At the beginning of a pre- or main wash phase, the controller 3 checks whether process water from a previous wash cycle is in the tank 2 and (optionally) whether its quality is sufficient. The quality can be measured for this purpose with the quality sensor 12, or e.g. also be derived from the storage time of the water in the tank. The course of the redox potential during the water treatment can, as described in more detail below, be used as a measure of the water quality.

If the quality of the process water in the tank 2 is sufficient, it will be fed through the valve 10 into the tub 1 during the prewash or main wash phase, where it will at most be supplemented with fresh water. Otherwise fresh water will be used during the pre- and main wash phase.

During the prewash and main wash phase, the process water in the tub 1 in the tub circulation line 4 can be pumped around, wherein the water switch 6 is set so that the process water is fed back into the tub 1 and not into the tank 2. At the end of the respective phase, the process water is led out of the device via a sewer line, not shown.

At the beginning of the washing phase, 1 fresh water is fed to the tub and the material is rinsed. Again, the process water can be pumped in the tub circulation line 4, the water switch 6 is again set so that the process water is fed back into the tub 1 and not in the tank 2.

At the end of the scavenging phase, the water diverter 6 is changed over and the process water is conveyed into the tank 2. In tank 2 it can be stored for the next wash cycle.

Before storing the process water in the tank 2, the process water is passed through the water treatment device 9, and even during storage, the process water from the tank 2 through the pump 8 through the water treatment device 9 can be performed. In order to treat the water in the process, a voltage is applied to the electrolysis cell, so that, as already mentioned, highly active molecules and in particular radicals are formed which kill germs and degrade organic contaminants.

In order to save power, the water treatment device is only operated at intervals during storage of the process water, wherein the controller 3 determines the time of a treatment interval. This can for example be purely time-controlled, i. the controller is designed to treat the process water stored in the tank 2 after a certain time with the water treatment device, e.g. once a day. Alternatively or additionally, the controller may use the signal from the quality sensor 12 to initiate the water treatment upon detection of some contamination.

The duration of a treatment depends on the amount of water to be treated, the current flowing through the water treatment device 9 and the interval between two treatments. A typical treatment time is about 10 - 40 minutes with a tank volume of about 4 - 10 liters, an interval interval of 24 hours and a current of about 1 A. It shows that in this way an odor formation in the process water over weeks can be avoided.

The current through the electrolysis cell depends on the applied voltage and the composition of the process water. Preferably, therefore, a control loop is provided to control the flow through the electrolytic cell by varying the voltage across the electrolytic cell. In order to avoid the generation of hydrogen, however, the voltage is limited to 50 volts.

In order to keep the voltage low for water with low conductivity, the conductivity can be increased by supplying the regeneration salt (NaCl) present in the dishwasher.

For this purpose, a small amount of salt is passed from the brine tank via the existing pump in the storage tank.

From the chloride ions is further formed by the diamond electrodes strongly bleaching and bacteria-degrading hypochlorite (HClO) (as Javelwasser), which strongly supports the hygiene effect.

An addition of 0.5- 1.5 g NaCl / l of water to be stored is i.A. completely adequate.

Thus, the household appliance is advantageously designed to supply regenerating salt to the water to be stored in the tank, in particular if the conductivity of the water falls below a threshold conductivity.

In order to avoid too high current densities, the area of the diamond electrode is preferably at least 10 cm ² , in particular approximately 20 cm ² .

The redox detector 11 may be used to monitor the function of the water treatment device 9 and / or to optimize the duration of a treatment and the interval between successive treatments by controlling the water treatment device according to the course of the redox detector 11 signal.

Fig. 3 shows the redox potential traces of clean and average polluted water to be stored, which has been treated with the diamond electrode.

With contaminated water, the redox potential drops more, and the output signal is only reached again after a considerably longer treatment time.

Due to the foreign substances in the polluted water radicals are formed, which influence the redox potential, the surface is proportional to the amount of radical generated.

The duration of treatment should now be selected until the output potential is reached again.

The starting potential depends on the water quality and can be in the range of 100 ... 300mV, but the waste depends on the pollution.

• Insbesondere kann die Steuerung 3 dazu ausgestaltet sein, die Behandlung des Prozesswassers mit der Wasserbehandlungsvorrichtung 9 abhängig vom Verlauf des Redox-Potenzials zu beenden.
• Zusätzlich oder alternativ hierzu kann die Steuerung 3 dazu ausgestaltet sein, eine nächste Aktivierungszeit der Wasserbehandlungsvorrichtung (9) abhängig vom Verlauf des Redox-Potenzials während der vorangehenden Behandlung festzulegen. Indem die Steuerung 3 dazu ausgestaltet ist, die nächste Aktivierungszeit (d.h. den Startzeitpunkt der nächsten Behandlung) abhängig vom Verlauf während der letzten Behandlung festzulegen, kann einer besonders hohen Verschmutzung durch kürzere Abstände zwischen aufeinander folgenden Behandlungen Rechnung getragen werden. Vorzugsweise wird also bei einer höheren Behandlungsdauer während der letzten Behandlung ein kürzerer zeitlicher Abstand bis zur nächsten Behandlung des Prozesswassers mit der Wasserbehandlungsvorrichtung 9 gewählt.

Consequently:

• In particular, the controller 3 may be configured to end the treatment of the process water with the water treatment device 9 depending on the course of the redox potential.
• Additionally or alternatively, the controller 3 may be configured to set a next activation time of the water treatment device (9) depending on the course of the redox potential during the previous treatment. By designing the controller 3 to set the next activation time (ie, the start time of the next treatment) depending on the course during the last treatment, a particularly high level of pollution due to shorter intervals between successive treatments can be accommodated. Preferably, therefore, at a higher treatment time during the last treatment, a shorter time interval until the next treatment of Process water selected with the water treatment device 9.

Fig. 2 shows a second embodiment of a household appliance. It differs from that according to Fig. 1 in that no circulation circuit is provided on the tank 2, which simplifies the device in terms of apparatus. The water treatment device 9 is arranged on the tub circulation line 4 in this case.

In this embodiment, the process water is treated before storage in the tank 2 with the water treatment device 9. For this purpose, the water is circulated during a certain treatment period in the tank circulation line 4 and the water treatment device 9 is activated, so that germs are killed. This is preferably done at the end of the wash phase. Then, the process water is transferred via the water switch 6 in the tank 2.

In this embodiment, the water can not be treated during its storage, unless it is conveyed back into the tub 1 and the tub circulation line 4, which is not favorable for many applications. However, with the treatment of the process water before storage, the storage time can already be greatly increased. Experiments show that the maximum storage time of average polluted process water increases from a maximum of 1.5 days to around 3 days.

In the execution after Fig. 2 For example, the controller 3 may be configured to treat the process water with the water treatment device 9 during a cleaning cycle, in particular during the main wash phase, thereby improving the cleaning process due to the resulting radicals. (In the execution after Fig. 1 this is also possible if, for example, suitable changeover valves are provided in order to optionally also insert the water treatment device 9 into the tub circulation line.)

In both of the described embodiments, a filter may also be provided, e.g. with a mesh size of 0.5 mm to filter the water before feeding into the tank 2, thus reducing soiling of the tank 2.

Furthermore, the tank 2 has a level sensor, which detects any leaks of the valve and the controller responds to the extent that when filling the first cleaning bath, the missing amount is added.

The level sensor can be realized via a conductivity measurement or an optical signal in the tank or via a flow water meter in the outlet of the tank.

The use of the water treatment makes it possible to avoid odors in the stored water for several days. In addition, pathogenic germs can be killed.

• Eine UV-Lichtquelle zur Behandlung des Prozesswassers kann ebenfalls dazu verwendet werden, Gerüche zu vermeiden und Keime abzutöten.
• Ein Ozongenerator kann ebenfalls dazu verwendet werden, Gerüche zu vermeiden und Keime abzutöten. Dem Ozongenerator wird Luft zugeführt, der diese in Ozon umwandelt und das Ozon in das Prozesswasser bläst.
• Ein Bioreaktor kann dazu verwendet werden, organische Substanzen abzubauen. Um einen aeroben Abbau sicherzustellen, wird dem Bioreaktor Luft zugeführt. Der aerobe Abbau führt im Vergleich zu einem anaeroben Abbau zu keinen Geruchsbelästigungen. Im Bioreaktor sind zur Oberflächenvergrösserung Kleinteile eingebracht, an denen die Mirkoorganismen kultiviert werden können.

In addition to an electrolytic cell with a diamond electrode, the water treatment device 9 can also have further parts, in particular:

• A UV light source for treating process water can also be used to prevent odors and kill germs.
• An ozone generator can also be used to prevent odors and kill germs. The ozone generator is supplied with air, which converts it into ozone and blows the ozone into the process water.
• A bioreactor can be used to break down organic substances. To ensure aerobic degradation, air is supplied to the bioreactor. The aerobic degradation leads to no odor nuisance compared to anaerobic degradation. In the bioreactor small parts are incorporated for surface enlargement, where the microorganisms can be cultivated.

Basically, it is freely selectable, which process water is supplied to the tank 2. Preferably it is, as mentioned, the last rinse water. For small amounts of bath or large tank, for example, a part of the penultimate rinse water can be introduced, possibly controlled in time.

The controller 20 offers the user the possibility, e.g. by selecting one or more specific programs to turn on or off the use of tank 2. In particular, he can disable the use of the tank 2 as well.

The device can, as already mentioned, be equipped with a contamination sensor 15, in particular an optical turbidity sensor, and the controller can suppress the temporary storage of process water in the tank 2, depending on the signal of the turbidity sensor 15. In this way it can be prevented that heavily polluted water is stored intermediately. The fouling threshold above which interim storage is suppressed may depend on the program that the user selects, and e.g. higher for a particularly ecological program than for other programs.

• Nach einem Netzunterbruch.
• Wenn die Lagerdauer eine Schwelle überschreitet (z.B. drei Tage).
• Bei expliziter Instruktion durch den Benutzer. Hierzu kann der Benutzer der Steuerung 3 mitteilen, dass sie den Tank 2 leeren soll, z.B. wenn er eine längere Abwesenheit plant.

During storage of the process water in the tank 2, this can be drained from the controller 3 under certain conditions, such as in the following cases:

• After a network interruption.
• If the storage duration exceeds a threshold (eg three days).
• With explicit instruction by the user. For this purpose, the user can tell the controller 3 that they should empty the tank 2, for example, if he plans a longer absence.

The tank 2 can be flooded with hot water regularly or at the user's request for cleaning and sanitation. For example, an automatic flooding can be initiated after 15 tank fillings in the next main wash phase. For a dishwasher this can be the water of the last bath, for example at 72 ° C heated and passed through the tank. The temperature is kept at about 70 ° C, until the expiration of eg 10 minutes.

The hygiene effect can be supported by adding detergent or chlorine tablets.

While preferred embodiments of the invention are described in the present application, it is to be understood that the invention is not limited thereto and may be embodied otherwise within the scope of the following claims.

Claims (16)

Household appliance comprising
a tub (1) for cleaning a material to be cleaned,
a tank (2) for temporarily storing process water discharged from the tub (1),
a controller (3) which is designed to convey process water from the tub (1) into the tank (2) and to transport the process water from the tank (2) back to the tub (1) in a later cleaning cycle with new material,
characterized by a water treatment device (9) having an electrolytic cell with at least one diamond electrode for treating the process water to be stored in the tank (2), the controller (3) being designed to store the process water before and / or during storage in the tank (2) to treat with the water treatment device (9). Domestic appliance according to claim 1, wherein the water treatment device (9) on a tank (2) arranged tank circulation line (7) is arranged and wherein the household appliance comprises a tank circulation pump (8) to the process water from the tank (2) through the Return the tank circulation line (7) to the tank (2). Domestic appliance according to one of the preceding claims, wherein the from the tub (1) in the tank (2) flowing process water flows through the water treatment device (9). Household appliance according to one of the preceding claims, wherein the domestic appliance has a tub circulation line (4), wherein on the tub circulation line a tub circulation pump (5) and a water diverter (6) are arranged, wherein with the tub circulation line (4) the process water via the water switch (6) either back into the tub (1) or in the tank (2) is feasible. Domestic appliance according to claim 4, wherein the water treatment device (9) is arranged on the tub circulation line (4). Domestic appliance according to one of the preceding claims, wherein the controller (3) is adapted to handle the stored in the tank (2) process water after a certain time and / or upon detection of a certain contamination with the water treatment device (9). Domestic appliance according to claim 6, wherein the household appliance has a quality sensor (12), in particular a gas detector, for measuring a degree of contamination of the process water in the tank (2). Domestic appliance according to one of the preceding claims with a detector for detecting a radical concentration of the process water, in particular with a detector (11) for detecting the redox potential of the process water, wherein the water treatment device (9) is controlled as a function of a signal of the detector (11). Domestic appliance according to claim 8, wherein the controller (3) is adapted to terminate the treatment of the process water with the water treatment device (9) depending on a course of the redox potential. Domestic appliance according to one of claims 8 or 9, wherein the controller (3) is adapted to set a next activation time of the water treatment device (9) depending on the course of the redox potential during a previous treatment. Domestic appliance according to one of the preceding claims, wherein a control circuit is provided to regulate a current through the electrolytic cell by varying a voltage across the electrolytic cell, but wherein the voltage is limited to at most 50 V. Domestic appliance according to one of the preceding claims, wherein the controller (3) is adapted to treat the process water during a cleaning cycle with the water treatment device (9). Domestic appliance according to one of the preceding claims, wherein the electrolysis cell has two diamond electrodes, wherein the household appliance is configured to apply a voltage between the two diamond electrodes with alternating sign. Domestic appliance according to one of the preceding claims, wherein the household appliance is configured to supply the water to be stored regenerating salt, in particular when the conductivity of the water falls below a Schwellleitfähigkeit. Domestic appliance according to one of the preceding claims, wherein the household appliance is a dishwasher. Household appliance according to one of claims 1 to 14, wherein the household appliance is a washing machine.

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