DE102012205827B4 - Method for assessing an aqueous liquid to be stored or stored in a household appliance and a household appliance suitable for this purpose - Google Patents

Abstract

Method for assessing an aqueous liquid (3,3`) stored or to be stored in a domestic appliance (1), the domestic appliance (1) having a control device (4), a treatment container (5) for receiving objects (7) to be treated, a storage container (2) for the aqueous liquid (3,3`) and a sensor (6,8,9,41), wherein with the at least one sensor (6,8,9,41) at least one property of the aqueous liquid (3.3') is measured and, depending on the measured at least one property, an assessment of a shelf life and/or usability of the aqueous liquid (3.3') in a treatment process is carried out, characterized in that the concentration and/or the change over time in the concentration of dissolved oxygen contained in the aqueous liquid (3,3`) can be used for the assessment.

Description

The invention relates to a method for assessing an aqueous liquid stored or to be stored in a domestic appliance and a domestic appliance suitable for this purpose. In particular, the invention relates to such a method and such a household appliance, in which the household appliance has a control device, a treatment container for receiving objects to be treated, a storage container for the aqueous liquid and at least one sensor.

The currently customary laundry treatment processes in a washing machine consist of several treatment steps (wetting phase, pre-wash, main wash, rinsing), each of which is associated with a more or less complete exchange of the aqueous liquid in the tub. The different types and amounts of polluted water that occur are usually disposed of as waste water, so that fresh water has to be used in future treatment steps. For example, each laundry treatment step generally begins with the supply of fresh water, which is disposed of as waste water at the end of the respective treatment step.

For the operation of a water-bearing household appliance (hereinafter also abbreviated to “household appliance”), for example a washing machine, water consumption is an important operating variable. For economic and ecological reasons, it is desirable to keep water consumption as low as possible, for example in a washing machine, minimal water consumption is specified due to the machine construction conditions and the suction behavior of the laundry to be treated.

In the treatment of soiled laundry in a washing machine, the actual washing step using suitable cleaning agents is generally followed by a rinsing phase with one or more rinsing steps with water. In this rinsing phase, the laundry items are freed from the washing liquor enriched with impurities and cleaning agents and any residues of impurities and cleaning agents adhering to the laundry items. The amount of such substances remaining on the fibers of the laundry items is lower when more water is used in rinsing and/or when water is rinsed more frequently. However, the time and amount of water used for rinsing are desired to be reduced while maintaining high rinsing efficiency in view of demands from users of washing machines and environmental protection.

In any case, saving water in water-bearing household appliances is an important issue against the background of an economically and ecologically responsible use of resources. To save water, it is known to provide household appliances with a storage tank so that water that has already been used can be reused in further treatment processes. For this purpose, an assessment of the condition of the stored aqueous liquid is important, with both an assessment of the instantaneous condition and an estimation of the storability of the stored water being useful. For any later use of the water in the treatment of objects (generally laundry, crockery), it should generally contain as little chemical and biochemical contamination as possible. However, an acceptable level of such contamination can be determined depending on the use of the stored water, preferably taking into account that biochemical contamination during the storage period allows the growth of microorganisms (yeasts, fungi, germs) and even the formation of a biofilms can occur. In particular, unpleasant odors often develop in microorganisms with decreasing oxygen content during the transition from aerobic to anaerobic growth, so that monitoring the oxygen concentration in an aqueous liquid can provide important information about the degree of contamination of the liquid. When a biofilm forms, parts of the biofilm can get into the treatment container when the stored liquid is used and lead to contamination of the treatment container and in particular of the objects to be treated there. It makes sense that depending on the level of contamination and possibly the storage time, a decision is made as to whether and when treatment of the stored water should be carried out. In addition, it may be that the load of dirt and microorganisms, e.g. germs, is so large that reuse, even after possible treatment, does not make sense and the stored water should therefore be disposed of.

The DE 197 09 085 A describes a method for washing laundry, in particular in a household washing machine, in which the laundry is treated in a tub during a washing section with washing liquid and during subsequent rinsing sections with rinsing liquid. At the end of the respective washing/rinsing section, the tub is emptied, with the washing liquid and/or rinsing liquid of at least one rinsing section being emptied into a collection container and after treatment be reused by a reverse osmosis, micro, ultra or nanofiltration process with intermediate storage in a storage tank. The processed washing or rinsing liquid is fed to a later rinsing section of the same program sequence.

The DE 38 05 565 A1 describes a method and a device for cleaning soiled parts using washing or rinsing water containing a washing or rinsing agent at an elevated temperature, in which, after the washing or rinsing process, the washing or rinsing water is passed through a filter which contains grease and/or or dirt is removed from the washing or rinsing liquor, and the washing or rinsing liquor filtered in this way with the washing or rinsing agent contained therein is then stored for use in a further washing or rinsing process.

The DE 102 37 853 A1 describes a method for measuring the amount of organic matter in a liquid, in which the amount of organic matter in the liquid is determined by means of a wet combustion and a determination of the degree of combustion. For this purpose, a predetermined quantity of ozone is introduced, passed through and discharged into a partial quantity of the liquid and the quantity of ozone discharged is measured by means of at least one arranged sensor and compared with the quantity of ozone introduced.

The DE 35 40 335 A1 describes a method for cleaning laundry in a household machine in which a reusable aqueous detergent solution is used. A circulatory system is used in which at least one filter is fitted and in which the wash liquor is stored between successive cleaning processes. Disturbing components are filtered out of the washing suds and it is possible to replenish the components of the washing suds that are consumed. In one embodiment, at least one sensor is installed in the circulatory system, which at least monitors the state of the washing suds and, depending on the output signal of the sensor, regulates at least one state parameter of the washing suds, in particular monitors and/or regulates a chemical component of the washing suds. The sensors used are used to monitor the wash suds in such a way that, if necessary, the amount of detergent and/or water is replenished.

The DE 10 2008 042 749 A1 describes a method for cleaning a spent liquor of a washing or cleaning machine with a container for washing or cleaning household items such as laundry or dishes using lyes that consist essentially of water and surfactant-containing detergents, the surfactants contained in the spent liquor by catalysis dismantled and the undissolved residues still contained in the spent caustic then filtered out. Depending on the purity after filtering, the waste caustic is either fed into the waste water outlet or stored. In a used washing or cleaning machine, a sensor is attached in the connection from the filter to the waste water outlet, which can determine the quality of the waste water.

The EP 2 397 062 A2 describes a household appliance comprising a tub for cleaning items to be cleaned, a tank for temporarily storing process water drained from the tub, and a controller which is designed to convey process water from the tub into the tank and in a later cleaning cycle with new items to transport the process water from the tank back to the vat. The household appliance has a gas sensor for detecting gases escaping from the process water stored in the tank, in particular ammonia, methane or hydrogen sulfide as typical decomposition products of the anaerobic bacterial metabolism.

The DE 29 10 140 A1 describes a method and a device for the automatic washing and rinsing of laundry. Fleets are collected in containers and stored there for recycling for the next wash batch. At least one rinsing liquor is collected and used as washing, cooling and/or rinsing liquor for the next wash batch. The washing liquors collected in the containers can be stored there for relatively long periods of time, for example several days. For this purpose, compounds which release hydronium ions, for example acetic acid, are advantageously added to the washing liquor. There is no sensor in the device described. A method for assessing an aqueous liquid stored or to be stored in a household appliance, in which at least one property of the aqueous liquid is measured with at least one sensor and, depending on the measured property, an assessment of the storability and/or usability of the aqueous liquid in a treatment process is made is therefore not described.

Against this background, the object of the invention is to provide a method for operating a household appliance with which an aqueous liquid stored or to be stored in a household appliance can be assessed so that a decision can be made about using the liquid. It is also the task of the inventor tion to provide a household appliance suitable for carrying out this method.

The object on which the invention is based is achieved by a method and a domestic appliance according to the respective independent patent claim. Preferred configurations of the invention are listed in the respective dependent patent claims. Preferred configurations of the method according to the invention correspond to preferred configurations of the household appliance according to the invention, even if this is not separately pointed out in each case.

The invention thus teaches a method for assessing an aqueous liquid stored or to be stored in a household appliance, the household appliance having a control device, a treatment container for receiving objects to be treated, a storage container for the aqueous liquid and at least one sensor, with the at least one sensor, at least one property of the stored aqueous liquid is measured and, depending on the measured at least one property, an assessment of a shelf life and/or usability of the aqueous liquid in a treatment process is carried out, the concentration and/or the change in the concentration over time of in dissolved oxygen contained in the aqueous liquid can be used for the assessment.

In the method according to the invention, the at least one property of the aqueous liquid is preferably measured in the treatment tank, storage tank and/or a line connecting them. Accordingly, at least one sensor is preferably located in the treatment tank, storage tank and/or a line connecting them. The at least one property of the aqueous liquid is particularly preferably measured in the storage container.

The term treatment process is to be interpreted broadly and, in addition to a cleaning process, which includes in particular washing and rinsing, can also include a process in which objects to be treated are to be provided with certain chemical substances (dyes, odors, etc.).

The assessment of the storage stability and/or usability of the aqueous liquid in a treatment process preferably includes a decision with regard to disposal, a required treatment or a special use of the aqueous liquid in a treatment process.

For example, the cleanliness requirements of an aqueous liquid are generally lower in a washing step than in a rinsing step. In addition, if a bleaching detergent is used in a washing step, microorganisms in the water can be killed, so that a small load of microorganisms in the stored aqueous liquid can be insignificant. In general, however, attempts will be made to use water with as little contamination as possible.

It is therefore advisable to process the liquid stored or to be stored at least when the contamination has exceeded a certain threshold value, which can depend on the intended use of the stored aqueous liquid.

According to the invention, it can be advantageous if an aqueous liquid to be stored is already reprocessed by filtration and/or treatment with an oxidizing agent before it is stored in the storage container.

In a preferred embodiment of the invention, the treatment of the aqueous liquid stored or to be stored comprises a filtration of the aqueous liquid and/or a treatment of the aqueous liquid with an oxidizing agent.

If the aqueous liquid stored or to be stored is to be processed, at least one filtration device and/or a chemical processing device is preferably provided in the domestic appliance.

The filtration device that may be used is not restricted according to the invention, as long as a desired filtration effect is achieved in one or more selected recycling steps. It is particularly advantageous if the at least one filtration device has an average pore size of ≧1 μm, ≦0.1 μm or ≦0.01 μm, or ≦0.001 μm. The filtration device is preferably a reverse osmosis device, a nanofiltration device, an electrodialysis device and/or an ion exchanger.

In the embodiments of the invention, the domestic appliance preferably contains at least two filtration devices with different average pore sizes and more preferably at least three filtration devices with different average pore sizes.

In a particularly preferred embodiment, the domestic appliance has three filtration devices, of which a first filtration device has an average pore size of ≧1 μm, a second filtration device has an average pore size of ≦0.1 μm and a third filtration device has an average pore size of ≦0. 01 µm.

In a very particularly preferred embodiment, a domestic appliance has four filtration devices, with a fourth filtration device having an average pore size of ≦0.001 μm also being present.

With an average pore size of approx. 1 µm, e.g. hair, pollen and sand can be removed. With an average pore size of approx. 0.1 µm, most bacteria and dust can be removed and with an average pore size of approx. 0.01 µm, viruses, dyes and soot can be removed. Finally, with even finer filters, e.g. with an average pore size of approx. 0.001 µm, e.g. surface-active agents can be removed.

If, for example, the intention is to remove dirt, viruses and bacteria, but not to remove washing-active substances and other laundry treatment agents, a filter range from 0.005 to 5 µm is used.

The filtration devices, if present in the household appliance according to the invention, are generally arranged in parallel, so that the aqueous liquid, e.g. from the tub or storage tank of a washing machine, can flow against them in a targeted manner. In principle, however, a series connection would also be possible. For this purpose, controllable supply lines to the filtration devices are generally present in the household appliance, so that these can be switched on independently of one another.

In the method according to the invention, the stored water can be cleaned of its contents by suitable filtration processes that are becoming ever finer.

After filtration through a relatively coarse filter, the stored or to be stored aqueous liquid can preferably be passed through a finer filter device (mean pore size e.g. ≤ 0.1 µm, ultrafiltration) in order to also remove larger molecules (e.g. surfactants, fats/waxes, degradation products enzymatic reactions).

This rinsing process is then preferably ended by using even finer filtration techniques (e.g. ≤ 0.01 µm, nanofiltration, removal of divalent ions) or finally by means of reverse osmosis (removal of all dissolved components from the water).

A reverse osmosis device is a device which, in a physical membrane filtration process known as reverse osmosis, allows substances dissolved in liquid to be concentrated by using pressure to reverse the natural osmosis process. In this way, water can be freed from dissolved components with almost no maintenance. There is no need for an exchange or regeneration. The result of reverse osmosis is on the one hand purified water and on the other hand more polluted water, both of which can be collected separately and used further.

If water with a higher concentration of impurities (insoluble dirt particles; inorganic or organic substances or ions) is obtained as a by-product during cleaning, its further use depends on the type and concentration of the impurity.

If at least one filtration device is present, a sensor for the functionality of the filtration device is preferably arranged in the domestic appliance. The sensor can be, for example, a per se known turbidity sensor. However, a sensor for registering the presence of a filter in a filtration device or a filter membrane or an ion exchanger cartridge in the household appliance (e.g. washing machine) can also be provided, for example.

A turbidity sensor can also be used to qualitatively and quantitatively detect insoluble particles, e.g. dirt particles, in the aqueous liquid.

The sensor is preferably connected to the program control and can thus be used to monitor the operability, i.e. filtration capability, of the filtration device. In this case, exhaustion of the filtration capacity of the filtration device can preferably be indicated when a predetermined maximum permissible content of impurities is reached or exceeded. If the filtration capability of the filtration device is running low, the turbidity value of the water exiting the filtration device, registered by a turbidity sensor, increases, for example.

The necessity of replacing the filter can then be indicated via an optionally present display device of the domestic appliance, eg a washing machine cal or a cleaning of the filtration device.

In any case, it is preferred that the washing machine also has a display device that can display one or more different circumstances, e.g. the display of the implementation of the method according to the invention for assessing an aqueous liquid stored in a household appliance or the display of the functional capability of the at least one filtration device, etc.

A user could be informed of the status of the stored or to be stored aqueous liquid by means of an optical or acoustic display, with a reference to a clean (e.g. via a green LED), one to be reprocessed (e.g. via an orange LED) or one to be disposed of ( e.g. via a red LED) watery liquid.

If a lack of functionality of the filtration device is indicated, for example because a filtration device is no longer sufficiently filtered or is even clogged, an acoustic and/or visual display can indicate that a filtration device needs to be cleaned or even replaced.

For example, one or more buzzers with different noises or tones, or a voice synthesizer with messages such as “change filter” or “clean filtration device”, “discard stored water” “recycle stored water” could be used as an acoustic display device. Corresponding qualitative and quantitative information about the presence of impurities such as dirt particles, grease or salts in the stored water or other inorganic and/or organic substances in the rinsing water and measures to be taken against them can, as mentioned, also be given via a visual display device (LED or LCD).

A chemical treatment device is preferably present in the domestic appliance for reprocessing by treating the stored aqueous liquid with an oxidizing agent. This can be a chamber in which an oxidizing agent is held or introduced. The oxidizing agent can then free a stored aqueous liquid fed into this chamber from chemical and in particular biochemical contaminants by oxidation or at least reduce their concentration.

The oxidizing agent can be added to the aqueous liquid in gaseous, liquid or solid form. The oxidizing agent can be, for example, hydrogen peroxide, another peroxide compound, a hypochlorite or ozone.

Ozone is advantageously used as the oxidizing agent. In this case, the domestic appliance used preferably has an ozone generator or else an opening or an intermediate store for an ozone-containing gas mixture or an ozone-containing liquid.

In general, the aqueous liquid is passed through the filtration device and/or the chemical treatment device using a pump. A pump that is generally present as part of a suds drainage system can be used for this purpose, for example in the case of a washing machine as a domestic appliance.

In embodiments of the invention in which at least one filtration device is present, the domestic appliance preferably has at least one sensor for determining the functionality of the filter device(s). According to the invention, a first sensor is preferred, which measures the contamination content, including dirt particles, treatment agents and/or salts, of the water exiting the filtration device.

In the method according to the invention, the property of the stored aqueous liquid is the concentration and/or the change in dissolved oxygen over time. However, turbidity and odor can also be used. The concentration of oxygen and/or its change is a good measure for assessing an aqueous liquid. If there is no or hardly any oxygen, microorganisms undergo a transition from aerobic to anaerobic growth, with the latter often being characterized by the formation of an unpleasant odour.

In the method according to the invention, therefore, the concentration and/or the change over time in the concentration of dissolved oxygen contained in the stored aqueous liquid are used for the assessment.

The measurement of the property, e.g., dissolved oxygen concentration, of the stored aqueous liquid may be continuous or discontinuous. In the case of discontinuous measurements, the time interval between the measurements generally depends on the degree of contamination to be expected.

The measured values determined can also be stored in order to implement a home appliance that is capable of learning. This means, for example, Messin intervals, threshold values such as the values S, S _processing and S _max mentioned below, and any reprocessing measures can be optimized, which can lead to cost savings. For example, depending on the household appliance and/or the liquids to be stored, it can happen that the aqueous liquid is only slightly contaminated and reprocessing is only rarely required. Correspondingly, in the case of a heavily contaminated aqueous liquid, it can happen that the state of the aqueous liquid is determined more frequently and/or a reprocessing is carried out. In addition, the threshold values can be increased or decreased depending on the measured and stored readings.

An oxygen sensor arranged in the storage container is preferably used to determine the oxygen dissolved in the aqueous liquid. Such a sensor can be, for example, an electrochemical or an optical oxygen sensor.

• (a) in der wässrigen Flüssigkeit, z.B. im Speicherbehälter, eine Konzentration c₁ an gelöstem Sauerstoff bereitgestellt wird;
• (b) die Abnahme Δc der Konzentration c₁ an gelöstem Sauerstoff nach einer vorgegebenen Zeit t_set mit einem, z.B. im Speicherbehälter angeordneten, Sauerstoffsensor gemessen und der Quotient Δc/t_set gebildet wird; und
• (c) der Quotient Δc/t_set zur Bestimmung eines Zustandsparameters S als Maß zur Beurteilung der wässrigen Flüssigkeit ausgewertet wird.

In a preferred embodiment of the method according to the invention, the change in the oxygen concentration in the stored water is used by

• (a) a concentration c ₁ of dissolved oxygen is provided in the aqueous liquid, eg in the storage container;
• (b) the decrease Δc in the concentration c ₁ of dissolved oxygen is measured after a predetermined time t _set with an oxygen sensor arranged, for example, in the storage container, and the quotient Δc/t _set is formed; and
• (c) the quotient Δc/t _set is evaluated to determine a state parameter S as a measure for assessing the aqueous liquid.

A chemical or biochemical oxygen demand (COD or BOD) can be used as the status parameter S, for example, as is used, for example, to characterize waste water. For this purpose, for example, a connection between COD and/or BOD and the measured property can be stored in the control device. In this case, various decisions to be made as a function of S can also be made by the control device and their implementation can be initiated. The chemical oxygen demand (CSB or COD, also known as chemical oxygen demand) is a measure of the sum of all substances present in the water that can be oxidized under given conditions. It indicates the amount of oxygen (in mg/l) that would be required to oxidize them if oxygen were the oxidizing agent. The chemical oxygen demand is used in particular to quantify the pollution of water with organic substances and as such includes both biodegradable and non-biodegradable substances as well as some inorganic substances.

This is to be distinguished from the biochemical oxygen demand BOD. Since the processes behind the consumption of oxygen cannot be concluded and it cannot be determined which substances are oxidized and how, it can be helpful to determine a biochemical oxygen demand, which assumes that the oxygen consumption is caused by the degradation of various organic substances is caused by bacteria and other microorganisms present in the water. It can make sense here that only organic carbon compounds are recorded as a result of the degradation. However, this can be disturbed by the biotic oxidation of inorganic nitrogen compounds (ammonia, ammonium ions). Any oxygen consumption that may occur due to nitrification is therefore sensibly suppressed by the addition of nitrification inhibitors (e.g. allyl thiourea).

In such an embodiment it is advantageous that part of the stored or to be stored aqueous liquid to be examined is provided with a nitrification inhibitor in a separate chamber in order to prevent contamination of the aqueous liquid to be reused.

For the evaluation, for example, a connection between the chemical or biochemical oxygen requirement and the quotient Δc/t _set can be determined in advance and stored in the control device, for example.

Provision can be made according to the invention for specific measures to be initiated for specific values or value ranges of S. For example, in the case of S≧S _max , the stored water can be disposed of.

In the case of S _treatment ≦S<S _max , it can be provided that a treatment takes place, with one or more filtrations and a chemical treatment being provided in this area depending on S.

According to the invention, it can also be provided that the storage container itself is cleaned automatically or via a request to the user, for example by introducing ozone. This could, for example, eliminate a biofilm that has formed.

Finally, a range of S for values of S<S _treatment can be provided, so that depending on the determined value S, one or more specific possible uses for the temporarily stored water are provided or permitted.

The values for S, S _processing and S _max are preferably stored in the control device of the domestic appliance.

In embodiments of the invention in which a display device is present in the domestic appliance, it can be provided that different value ranges of S are assigned different displays, for example by using different colored LEDs as described in more detail above.

The signals measured by one or more sensors, of the same or different type, can be combined, optionally also with a temperature measurement. An even more precise assessment of the stored aqueous liquid can thus be carried out and, if necessary, an expected change over time in the quality of the stored or to be stored aqueous liquid with regard to the storability can be estimated even better.

The oxygen sensor used in embodiments of the invention is generally an optical or an electrochemical oxygen sensor. A particularly suitable electrochemical oxygen sensor is, for example, a Clark electrode. In a Clark electrode, an electrolyte solution containing a cathode and an anode is separated from a solution to be examined by means of an oxygen-permeable membrane. Dissolved oxygen present in the solution to be examined, in this case the stored aqueous liquid to be examined, diffuses through the membrane according to its concentration and is reduced there at the cathode with the formation of hydroxide ions. The reduction current is thus a measure of the amount of oxygen. For example, the Clark electrode consists of a platinum cathode and a silver anode, both of which are immersed in an electrolyte solution. However, gold cathodes and lead anodes are also possible. The membrane usually consists of a fluoropolymer.

A particularly suitable optical oxygen sensor is an optode. An optode generally comprises a transmitter (also referred to as a "chemical transducer"), a substrate to which it is attached, e.g. a polymer, and a measuring device, whereby various optical properties such as reflection, absorption or luminescence, preferably luminescence, are measured can become.

In the case of a two-piece optode, the measuring device is in contact with the stored or to be stored aqueous liquid, i.e. in particular in the treatment tank, storage tank and/or a line connecting them, while the measuring device is also outside of the treatment tank, storage tank and/or a line connecting them may be appropriate. In this case, however, there should be an optically permeable, in particular transparent, (section) of the wall between the sensor and the measuring device.

One-piece optodes that can be introduced as such into an aqueous liquid to be examined are particularly advantageous. The one-piece optode contains, for example, a photo element, an excitation source, e.g. with gentle green light, and a membrane on which there is a pigment layer. A suitable optode of this type is available, for example, from WTW under the designation FDO 700 IQ.

In a preferred embodiment of the method, if the concentration of dissolved oxygen falls below a predetermined concentration c _set1 or if a predetermined value for the decrease over time (dc/dt) _set1 of the concentration of dissolved oxygen in the aqueous liquid is exceeded, the aqueous liquid is processed in a processing device , For example, a filtration device and / or a chemical treatment device performed.

It is preferred here that the treatment comprises a filtration of the aqueous liquid and/or a treatment of the aqueous liquid with an oxidizing agent.

Furthermore, in the method according to the invention it is preferred that the aqueous liquid is disposed of when the dissolved oxygen concentration falls below a predetermined concentration c _set2 <c _set1 or if a predetermined value for the decrease over time (dc/dt) _set2 >(dc/dt) _set1 is exceeded .

The invention also relates to a domestic appliance for treating objects, comprising a control device, a treatment container for accommodating objects to be treated, a storage container for an aqueous liquid and at least one sensor, the control device and the at least one sensor being designed to communicate with the at least a sensor to measure at least one property of the aqueous liquid in the storage tank and depending on the measured property is able to make an assessment of the storability and/or further usability of the stored aqueous liquid in a treatment process, the concentration and/or the change over time in the concentration of dissolved oxygen contained in the aqueous liquid being used for the assessment.

The at least one sensor is generally arranged in the storage tank, the treatment tank and/or a line connecting them and includes an oxygen sensor and optionally also an odor sensor and/or a turbidity sensor.

A turbidity sensor is a sensor known per se, in which the turbidity caused by impurities in an aqueous liquid is measured optically.

The term odor sensor here means a sensor for a substance that is at least partially in the gaseous state at room temperature. "Gas" therefore means not only in the narrower sense a substance that is in the gaseous state at room temperature, but also those parts of a more or less volatile substance that are present as an effective part in the gas phase at room temperature due to a finite vapor pressure. Since an odor is a complex phenomenon, at least two gas sensors are different in an odor sensor such as is used in embodiments of the invention, ie they are intended for different substances. At least two gas sensors, preferably 3 to 50 and particularly preferably 5 to 40 gas sensors, are particularly advantageously used. Further information on odor sensors can be found, for example, in DE 10 2008 054 462 A1 to find.

According to the invention, an oxygen sensor is used, for example an electrochemical or an optical sensor, as described in more detail above, or a combination thereof.

The household appliance according to the invention is generally a water-bearing household appliance such as a washing machine, a washer-dryer, a tumble dryer or a dishwasher. The domestic appliance is preferably a washing machine, a washer-dryer or a dishwasher.

The size of the storage container can vary over a wide range. If the household appliance is a washing machine, the capacity of the storage container for an aqueous liquid is generally approximately 70 to 90% of the water volume provided for washing 6 to 8 kg of laundry. If, for example, 14 to 18 liters of water are provided for washing 6 to 8 kg of laundry, the storage capacity of the storage containers is 10 to 16 liters in a preferred embodiment.

The domestic appliance preferably has an optical and/or acoustic display device with which the implementation of a method according to the invention that is taking place and/or a result of this method can be displayed. Based on a displayed assessment of the aqueous liquid stored or to be stored, a user of the household appliance can then make a decision about the further use of the stored aqueous liquid and initiate suitable steps. For example, reaching or exceeding the value S _max of the state parameter S could be indicated acoustically and/or optically.

In the domestic appliance according to the invention, there is a control device which, in addition to controlling the method according to the invention, can generally also control the treatment method. The control device can thus make a decision about the disposal of the stored aqueous liquid, ie exclude reuse and/or cause a corresponding acoustic and/or visual display on a display device.

In a preferred embodiment of the invention, in which the household appliance is a washing machine, a pressure sensor and/or a temperature sensor are arranged in the tub. Pressure and temperature sensors, if present, are preferably arranged in a lower area of the tub, so that the pressure and/or temperature of an aqueous liquid present in the tub can be measured.

In addition, a washing machine generally has a tub and a drum, which is rotatably mounted in the tub and preferably rotatably horizontally, for receiving items of laundry to be cleaned. Both are considered herein as treatment vessels. In addition, a washing machine generally also has a suds drainage system with a suds pump arranged on the bottom of the tub, and generally also laundry entrainment devices and/or scoop devices.

The invention has the advantage that it is possible in a simple and efficient manner to optimally use an aqueous liquid stored in a domestic appliance. The measurement of properties of the stored or to be stored aqueous liquid not only allows a Beur Sharing a storability and / or usability of the aqueous liquid and thus information and decision of a user of the household appliance, but also an automatic decision with regard to the further use or treatment of the stored aqueous liquid. This achieves a general improvement in the hygiene of the household appliance, which can also be specifically improved for special user groups such as allergy sufferers.

In addition, the invention is advantageous in the case of a washing machine or a washer-dryer if, for example, laundry is to be washed at a reduced washing temperature, for example at a temperature in the range from 15 to 20°C. It is sometimes feared that these low temperatures are not sufficient to kill microorganisms. The present invention also contributes in particular to improving hygiene in such washing methods, in that, in embodiments of the invention, microorganisms can be separated from the washing or rinsing water by means of e.g. reverse osmosis or dialysis or can be killed by an oxidizing agent. The invention makes it possible for such a treatment to be carried out only for specific uses and/or for specific degrees of contamination.

In embodiments, the invention makes it possible for the quality of the stored water to be guaranteed, so that it can be so clean that it can easily be used instead of fresh water, for example, for wetting and washing laundry. In addition, already cleaned and in particular desalinated, stored water has the advantage that the detergent concentration does not have to be adjusted with regard to the degree of hardness, even if it has gone through a rinse cycle according to the invention. Thus, the used rinsing water is even more advantageous as washing water than fresh water. The stored water is therefore very particularly preferably used in a wash cycle of a subsequent washing process.

Finally, in certain embodiments, the invention makes it possible to reduce the load on the laundry with undesirable salts and other inorganic and/or organic substances, so that the use of fabric softener can be reduced or avoided.

• 1 ist eine schematische Darstellung einer frontalen Schnittansicht einer ersten Ausführungsform einer Waschmaschine als Beispiel für ein erfindungsgemäßes Hausgerät, die neben einem Speicherbehälter für eine wässrige Flüssigkeit als Aufbereitungsvorrichtungen für die gespeicherte wässrige Flüssigkeit eine erste und eine zweite Filtervorrichtung sowie eine chemische Aufbereitungsvorrichtung aufweist.
• 2 ist eine vergrößerte Ansicht der für die vorliegende Erfindung relevanten Teile einer Waschmaschine als einer Ausführungsform eines erfindungsgemäßen Hausgerätes.

Embodiments of the invention are described below with reference to 1 and 2 illustrated, with a washing machine being given as an example of a household appliance according to the invention.

• 1 is a schematic representation of a front sectional view of a first embodiment of a washing machine as an example of a household appliance according to the invention, which, in addition to a storage container for an aqueous liquid, has a first and a second filter device and a chemical treatment device as treatment devices for the stored aqueous liquid.
• 2 13 is an enlarged view of the parts relevant to the present invention of a washing machine as an embodiment of a household appliance according to the invention.

In the schematic representation of 1 the parts of a washing machine 1 relevant to the invention, in which a method according to the invention can be carried out, are shown. Other embodiments are conceivable. The washing machine 1 has a tub 20 in which a laundry drum with items of laundry 7 located therein can be rotatably mounted as the treatment container 5 and can be operated by a drive motor 14 . 17 denotes an axis of rotation of the drum. In cooperation with laundry drivers 33 and scooping devices 34 for the washing suds or rinsing water 37, a good flooding of the items of laundry 7 with washing suds or rinsing water 37 is achieved. In particular, rinsing water from one of the last rinsing cycles can be analyzed as the aqueous liquid 3' to be stored using the method according to the invention. The washing machine 1 has a suds supply system that includes a water connection for the domestic water network 18, an electrically controllable valve 19 and a supply line 32 to the suds container 20, which is routed via a dispensing bowl 22, from which the incoming fresh water treatment agent can be transported into the suds container 20 . A heating device 13 is located in the tub 20. Valve 19 and heating device 13 can be controlled by a program control 4, which also controls the method according to the invention, depending on a program flow chart. A pressure sensor 15 is provided for measuring the hydrostatic pressure p in the tub 20 .

An aqueous liquid 3 can be temporarily stored in a storage container 2 for further use in the washing machine. For this purpose, a rinsing or washing liquid 37, usually a relatively clean rinsing liquid 3' from one of the last rinsing cycles, is conveyed into the storage container 2 via a storage line 35 by means of the pump 16. It is possible here that the rinsing or washing liquid 37 is first cleaned in a treatment device 10, 11, 12 before it is introduced into the storage container 2. For this, the Rinsing or washing liquid 37 from the tub 20 via the central filtration line 23 through one or both filtration devices 10 and 11 and through the chemical treatment device 12 are passed. The purified aqueous liquid obtained in this way can then reach the central connecting line 28 and from there into the storage container 2 via supply lines, which are not numbered in detail here. The liquid coming from the chemical treatment device 12 in this embodiment cannot get into the tub 20 when the closure 29 is closed, but is fed back into the storage container 2 .

A sensor 6 for measuring a property of the stored aqueous liquid 3 is located in the storage container 2, so that a control device 4 can use a control device 4 to assess the storability and/or usability of the stored aqueous liquid 3 in a treatment process depending on the measured property can be. In this case, the assessment of the storability and/or usability of the aqueous liquid 3 in a treatment process includes a decision with regard to disposal, a required treatment or a special use of the aqueous liquid 3 in a treatment process.

The sensor 6 is an oxygen sensor for determining the properties of dissolved oxygen content and/or change in dissolved oxygen concentration. In the embodiment shown here, the oxygen sensor 6 is used to determine the properties of dissolved oxygen content and/or change in the concentration of dissolved oxygen, e.g. a Clark electrode or a one-piece optode. This enables the concentration and/or the change over time in the concentration of dissolved oxygen contained in the stored aqueous liquid 3 to be used for the assessment. An oxygen sensor 6 arranged in the storage container 2 is thus used to determine the oxygen dissolved in the aqueous liquid.

1. (a) in der wässrigen Flüssigkeit 3,3`, z.B. im Speicherbehälter 2, eine Konzentration c₁ an gelöstem Sauerstoff bereitgestellt wird;
2. (b) die Abnahme Δc der Konzentration c₁ an gelöstem Sauerstoff nach einer vorgegebenen Zeit t_set mit einem, z.B. im Speicherbehälter angeordneten, Sauerstoffsensor 6,41 gemessen wird; und der Quotient Δc/t_set
3. (c) zur Bestimmung eines Zustandsparameters S als Maß für die Qualität der wässrigen Flüssigkeit 3,3` ausgewertet wird.

In the washing machine 1, a method according to the invention can be carried out in which

1. (a) a concentration c ₁ of dissolved oxygen is provided in the aqueous liquid 3,3`, for example in the storage container 2;
2. (b) the decrease Δc in the concentration c ₁ of dissolved oxygen is measured after a predetermined time t _set with an oxygen sensor 6, 41 arranged, for example, in the storage container; and the quotient Δc/t _set
3. (c) is evaluated to determine a state parameter S as a measure of the quality of the aqueous liquid 3,3`.

In 1 It is not shown in detail how, for example, oxygen-rich air is fed into the storage container 2 for step (a).

At the in 1 In the embodiment of a household appliance shown, the treatment of the stored or to be stored aqueous liquid 3, 3' can include, for example, filtration and/or treatment with an oxidizing agent such as ozone.

In the washing machine of the embodiment of FIG 1 If the concentration of dissolved oxygen falls below a specified concentration c _set1 or if a specified value for the decrease over time (dc/dt) _set1 in the concentration of dissolved oxygen in the aqueous liquid 3, 3` is exceeded, the aqueous liquid 3 is processed in a Processing device 10,11,12 carried out. The treatment includes a filtration of the aqueous liquid 3, 3' and/or a treatment of the aqueous liquid 3, 3' with an oxidizing agent. In addition, the aqueous liquid 3, 3' is disposed of if the concentration c _set2 <c _set1 of dissolved oxygen falls below a predetermined level or if a predetermined value for the decrease over time (dc/dt) _set2 >(dc/dt) _set1 is exceeded.

In this embodiment, the control device 4 and the sensor 6 are designed to measure a property of the aqueous liquid 3 in the storage container 2 with the sensor 6 and, depending on the measured property, to assess the storability and/or further usability in one to carry out treatment procedures.

At the in 1 shown first embodiment of a washing machine according to the invention, two filtration devices 10 and 11 with different filters 30 and 31 are present. The first filter 30 in the first filtration device 10 has an average pore size of ≦0.1 μm, while the second filter 31 in the second filtration device 11 has an average pore size of ≦0.01 μm. Depending on the assessment of the stored aqueous liquid, it can therefore be provided for the filtration that a filtration is carried out in one or both filtration devices. In particular, after filtration in the first filtration device 10, the aqueous liquid can be passed into the second filtration device 11 via a filtration connection line 26, so that the stored aqueous liquid 3 can be passed through filtration devices can be filtered with increasing fineness. The operability of the filtration devices can be monitored via sensors (not shown here), for example in the processing connection line 40 .

In the lower area of the tub 20 there is a sensor (conductivity sensor, turbidity sensor) not shown in detail, with which the content of soluble and insoluble inorganic and organic substances in the aqueous liquid used in the tub 20 can be determined. Thus, even before the aqueous liquid 3' is stored in the storage container 2, the aqueous liquid originating from the tub 20 can be processed.

For this purpose, data stored in a memory of the control device 4 on the relationship between the type and concentration of particulate impurities, salts, etc. and, for example, the turbidity can be used.

In addition, a one-piece optode 41 for measuring the oxygen concentration is arranged in the lower area of the tub 20 .

A display device 21 is located on the washing machine 1 for the acoustic and/or visual display of the implementation of a method according to the invention and/or the result of the assessment of the aqueous liquid, e.g. a lack of hygiene and/or an improperly functioning filtration or chemical treatment.

A pump 16 conveys the aqueous liquid 37 or 3' out of the tub 20 so that it can reach either the storage container 2 directly or one of the three reprocessing devices 10,11,12. In this embodiment, the pump 16 is part of the suds drainage system of the washing machine 1. Waste water can be disposed of via the waste water line 36 by means of the pump 16.

2 Fig. 12 is an enlarged schematic view of the relevant parts of a washing machine as an example of a home appliance according to the invention.

In the embodiment of 2 two oxygen electrodes are arranged in the storage container 2, namely a two-piece optode 9 as an optical sensor and a Clark electrode 8 as an electrochemical sensor. The optode 9 comprises a sensor 39 in a polymer matrix, which is arranged in the storage container 2 on a container wall that is optically permeable at least in this area and has a luminescence that is dependent on the oxygen content of the surrounding aqueous liquid 3, as well as a measuring device 38. The luminescence is measured with a outside on the container wall of the storage container 2 arranged measuring device 38 registered.

An aqueous liquid 37 or 3' can be pumped from the tub 20 into the storage container 2 via a storage line 35 by means of a pump (not shown here) and temporarily stored there as a stored aqueous liquid 3. Depending on the dissolved oxygen content of the aqueous liquid 3, 3` determined by the oxygen electrodes 8 and 9 in the storage container 2 or by the one-piece optode 41 as an oxygen electrode in the tub 20 or a determined change in the oxygen concentration over time, it can be decided whether the aqueous Liquid 3.3' discarded, i.e. disposed of, reprocessed or can be used directly again in the tub 20.

In the embodiment of 2 the recycling of the aqueous liquid 3 is shown in more detail. For this purpose, the aqueous liquid 3 gets, using a pump (not shown here), via the central filtration line 23 either into a first filter device 10 or via a chemical treatment line 27 into a chemical treatment device 12. In the first filter device 10, the aqueous liquid 3 is not filter shown. The filtered solution can then reach the storage container 2 again via the central connecting line 28 without any further treatment step. If desired, the filtration is followed by chemical reprocessing, eg by treatment with an oxidizing agent. For this purpose, the filtered aqueous liquid is fed into the chemical treatment device 12 via the treatment connection line 40 . The aqueous liquid 3 treated with an oxidizing agent can then be fed back into the storage tank 2 via the central connecting line 28 . Conversely, in the embodiment of 2 Incidentally, a chemical reprocessing in the chemical processing device 12 and then, in particular in the case of more heavily contaminated aqueous liquids, a filtration in the first filtration device 10 can also be carried out first. In principle, a chemical treatment can also be switched between filtration processes. The aqueous liquid reprocessed in this way can be fed back into the storage container 2 via the central connecting line 28 .

In both cases, finally, the reprocessed aqueous liquid without further intermediate storage in the storage tank 2 on the Lead 32 passed into the tub 20 and used there for a treatment program.

Reference List

1

Household appliance, e.g. washing machine

2

storage tank

3

stored aqueous liquid

3`

aqueous liquid to be stored

4

control device

5

Treatment container, e.g. laundry drum

6

Sensor; Oxygen sensor (Clark electrode, optode)

7

laundry items

8th

Clark electrode

9

two piece optode

10

first filtration device

11

second filtration device

12

chemical treatment device

13

heating device

14

drive motor

15

pressure sensor

16

pump

17

axis of rotation of the drum

18

domestic water network

19

Valve

20

tub

21

display device

22

dispenser bowl

23

central filtration line

24

first filtration line

25

second filtration line

26

filtration connection line

27

chemical processing line

28

central connection line

29

closure

30

first filter

31

second filter

32

Supply line (between the induction bowl and the suds container)

33

laundry carrier

34

scoop device

35

storage line

36

sewer line

37

suds, suds

38

Measuring device for optical signals, e.g. luminescence signals

39

transducer

40

processing connection line

41

one-piece optode

Claims (14)

Method for assessing an aqueous liquid (3,3`) stored or to be stored in a domestic appliance (1), the domestic appliance (1) having a control device (4), a treatment container (5) for receiving objects (7) to be treated, a storage container (2) for the aqueous liquid (3,3`) and a sensor (6,8,9,41), with the at least one sensor (6,8,9,41) having at least one property of the aqueous liquid (3.3') is measured and, depending on the measured at least one property, an assessment of a shelf life and/or usability of the aqueous liquid (3.3') in a treatment process is carried out, characterized in that the concentration and/or the change over time in the concentration of dissolved oxygen contained in the aqueous liquid (3,3`) can be used for the assessment. procedure after claim 1 , characterized in that the assessment of the storability and/or usability of the aqueous liquid (3.3`) in a treatment process involves a decision with regard to disposal, a necessary treatment or a special use of the stored aqueous liquid (3.3`) included in a treatment process. procedure after claim 2 , characterized in that the treatment comprises a filtration of the aqueous liquid (3.3`) and/or a treatment of the aqueous liquid (3.3`) with an oxidizing agent. Procedure according to one of Claims 1 until 3 , characterized in that the property of the aqueous liquid (3,3`) is selected from the group consisting of turbidity, odor, dissolved oxygen content and change in dissolved oxygen concentration. Procedure according to one of Claims 1 until 4 , characterized in that in the storage tank (2), in the treatment tank (5) and / or in an oxygen sensor (6,8,9,41) arranged connecting this line (23,35) is used to determine the oxygen dissolved in the aqueous liquid (3,3`). Procedure according to one of Claims 1 until 5 , characterized in that (a) a concentration c <sub>1</sub> of dissolved oxygen is provided in the aqueous liquid (3,3`); (b) the decrease Δc in the concentration c ₁ of dissolved oxygen is measured after a predetermined time t _set with an oxygen sensor (6,8,9,41) and the quotient Δc/t _set is formed; (c) the quotient Δc/t _set is evaluated to determine a state parameter S as a measure for assessing the aqueous liquid (3.3`). procedure after claim 5 or 6 , characterized in that the oxygen sensor (6) used is an optical or an electrochemical oxygen sensor. procedure after claim 7 , characterized in that the electrochemical oxygen sensor (6) is a Clark electrode (8). procedure after claim 7 , characterized in that the optical oxygen sensor (6) is an optode (9.41). Procedure according to one of Claims 1 until 9 , characterized in that if the concentration of dissolved oxygen falls below a predetermined concentration c <sub>set1</sub> or if a predetermined value for the decrease over time (dc/dt) <sub>set1</sub> of the concentration of dissolved oxygen in the aqueous liquid (3,3`) is exceeded, a treatment of the aqueous Liquid (3.3') is carried out in a treatment device (10,11,12). procedure after claim 10 , characterized in that if the concentration of dissolved oxygen falls below a predetermined concentration c _set2 < c _set1 or if a predetermined value for the decrease over time (dc/dt) _set2 > (dc/dt) _set1 is exceeded, the aqueous liquid (3, 3`) is disposed of. Domestic appliance (1) for treating objects (7), comprising a control device (4), a treatment container (5) for receiving objects (7) to be treated, a storage container (2) for an aqueous liquid (3,3`) and at least one sensor (6,8,9,41), wherein the control device (4) and the at least one sensor (6,8,9,41) are designed to use the at least one sensor (6) at least one property of the aqueous To measure liquid (3.3') and, depending on the measured property, to make an assessment of the shelf life and/or further usability of the aqueous liquid (3.3') in a treatment process, characterized in that the concentration and/or the temporal change in the concentration of dissolved oxygen contained in the aqueous liquid (3.3`) can be used for assessment. Household appliance (1) according to claim 12 , characterized in that the at least one sensor (6,8,9,41) is arranged in the storage tank (2), treatment tank (5) and/or a line (23,35) connecting them and is selected from the group which an odor sensor, a turbidity sensor and an oxygen sensor. Household appliance (1) according to Claim 13 , characterized in that the oxygen sensor (6,8,9,41) is an electrochemical oxygen sensor (8) or an optical oxygen sensor (9,41).

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