EP1048912B1 - Refrigerating apparatus and method for indicating germs - Google Patents

Abstract

The appliance (1) has a circulating fan (9), an electrochemical sensor (3), an electronic comparator (4) and indication unit which indicates the exceeding of a reference nitrite concentration value of the sensor by the electronic unit.

Description

The invention relates to a cooling device according to the preamble of claim 1. Such a cooling device is known from US-A-5 230 220. Also concerns the invention a method for indicating germs in such a cooling device.

Refrigerators are useful for short-term storage of various foods and foods different low temperatures suitable. Design and arrangement of an evaporator (e.g. plate-shaped, with or without evaporator compartment, integrated in the rear wall) as well as a practical one Subdivision of the interior allow the groceries to the appropriate Store levels in the optimal temperature range for them.

In contrast to static cooling, where cooling is dependent on the cooling zone and the Evaporator is located on the rear wall or in the upper area of the device, conquered in dynamic cooling market in recent years. This is the cold air distributed in the refrigerator by a fan. The food can be independently in the refrigerator be stored from the location at a constant temperature. It is particularly advantageous in addition to the uniform distribution of cold and air humidity, rapid cooling of the food brought in, however, this way existing or emerging germs, Mushrooms and spores spread faster.

Moisture emitted by the stored food or by warm air enters the refrigerator when the door is opened and condenses on the evaporator. To those there keep the resulting frost layer as low as possible and also the food in front of you It shouldn't dry out and prevent the transfer of taste from one another only odor-intensive foods should be kept in closed containers. Although that It is generally known that many foods are still stored in the refrigerator, even when they are not packed. Germs, fungi or spores adhering to the food or containers both through natural and dynamic air circulation in the interior and on the Food or distributed on the receiving containers. Because with a thicker one Frost layer both the heat transfer to the refrigerant in the evaporator and worse the temperature control should become more inaccurate, should be defrosted regularly. Independently, whether defrosted by hand or semi-automatically, this is inevitable with germs and Condensate containing spores is stored in a collecting container below the evaporator collected. With an automatic defrosting process, there is a large-area rear wall evaporator available. The defrost water runs through a below the evaporator Arranged gutter through a small tube on the rear wall of the cooling unit in one Condensate trap, which is arranged on the compressor or on the condenser. The Condensation evaporates due to the heat there.

DE 23 44 261 A1 describes a cooling device with a recirculation system in the interior, the air is forced through a filter device. As a result, those occurring in the interior should Odors can be effectively eliminated. With such a structure, the Improve the smell inside the refrigerator, but the movement of air will inevitably present germs, fungal spores or similar undiminished over the whole Interior distributed. These germs and / or are not killed in the filter device Spores. Experience has shown that the refrigerator is usually only cleaned when it is visible Soiling occurs. Before germs and / or spores for the human eye visible, the interior is already loaded with these.

EP 312 060 B1 also describes an automatic cooling device with a device for Air circulation. However, a separate storage compartment is included in this cooling unit is limited by plastic material. The device for air circulation generated in this Fan forced ventilation via a germicide. The germs are killed by ultraviolet rays without the tray itself being exposed to the ultraviolet rays. at such a device is indeed a closed compartment in which a germicide done, but such a device for killing germs is not directly on the whole Storage space transferable. Ultraviolet rays are in shadow areas as well as in Biofilms and soiling on the food or storage containers not effective. However, biofilms are usually not visible. The user must therefore get away from it assume that in the refrigerator interior outside the locked compartment undesired Bacteria or germs can be present. A time for a necessary cleaning cannot be derived from it. Again, the user is visible at Dirt remove the interior walls thoroughly. Then there is one Distribution of germ growth is often well advanced.

Furthermore, a cooling device is known from US Pat. No. 5,230,220, the cooling device in the interior a measuring device with at least one sensor designed as an odor sensor and an evaluation electronics. Depending on whether the amount of the odor sensor detected odors increases or decreases, an electrical voltage is changed. This Voltage is measured in an electrical comparator with a predetermined electrical Reference voltage compared. Depending on the comparison of the two electrical An LED and a sterilizing and deodorising unit are switched on.

The invention thus presents the problem of creating a cooling device in which even an apparently clean interior is an indication of recommended interior cleaning occurs because the number of germs actually present is increased.

According to the invention, this problem is solved by a cooling device with the one specified in claim 1 Features and a method according to claim 12 solved. Advantageous refinements and developments of the invention result from the following subclaims.

The advantages achievable with the invention are, in particular, that the user already pointed out a sensible cleaning or a disinfectant renovation of the interior if a significant number of germs and / or spores or similar are present, but no visible contamination can be determined. This is in the Cooling device flushed at least one sensor on one of condensate from the interior Place arranged. The measuring device advantageously consists of at least one sensor Detection of bacteria, yeasts, mold and / or their metabolic products, an evaluation electronics and / or a display element together. The right time for cleaning is in particular by comparison with those stored in the evaluation electronics Limit values determined and signaled. Exceeds the current measured value Bacteria, yeasts, molds and / or their metabolites, e.g. Nitrite concentration, the comparison or limit value is shown in a further advantageous embodiment in recurring intervals a warning is given via a display element. This Warning is given either optically and / or acoustically. One is particularly advantageous Arrangement of the sensor in or on a condensate trap or on the Back wall evaporator, because there is guaranteed wetting of the sensor with condensate. In another advantageous embodiment is between the condensate drain and the Rear wall evaporator arranged a drip tray, which is in contact with the sensor. Since it is known that a large number of bacteria produce nitrite as a metabolite, the Sensor advantageously equipped as a nitrite sensor. This either directly captures the im Condensate nitrite or the oxidation is used as a measuring method and nitrite oxidized to nitrate.

Figur 1

Kühlgerät ohne Tür

Figur 2

Kühlgerät mit geöffneter Tür

An embodiment of the invention is shown purely schematically in the drawings and is described in more detail below. It shows

Figure 1

Refrigerator without a door

Figure 2

Refrigerator with the door open

FIG. 1 shows a cooling device (1) in the form of a refrigerator, for a better overview the door (10) has been omitted. The refrigerator (1) has a heat-insulated housing an interior (2) with smooth side walls. The division of the interior (2) can be designed differently. Usually there is at least one, here Not shown, vegetable bowl and in several levels storage space for refrigerated goods. Naturally the interior (2) can also be divided in such a way that multi-part shells side by side be inserted and / or in the upper area an additional freezer compartment is arranged.

The refrigerator (1) can be equipped as a multi-temperature refrigerator. Likewise is it is possible to have the cooling device (1) in at least two interiors (2) separated from one another to divide separately assigned doors. A particularly good indoor climate leaves reach themselves with dynamic cooling. Here one ensures in the upper interior area arranged fan (9) for good air flow and thus for even Temperatures throughout the interior (2). In addition, the refrigerated goods stored become a lot cooled faster.

Regardless of the interior design, it is with constant use of a refrigerator (1) unavoidable that bacteria adhering to food or its packaging, Yeast, mushrooms or similar spread quickly in the interior (2) of the refrigerator (1). Therefore in the cooling device (1) integrates a measuring device (3, 4, 5) which is capable of direct or indirect quantification of germs and spores present in the interior (2). In addition to a sensor (3), this measuring device (3, 4, 5) includes, for example is designed as an electrochemical or biochemical sensor, at least one evaluation electronics (4) and advantageously also a display element (5). It becomes the total bacterial count determined directly or indirectly and with a basic limit value stored in the evaluation electronics (4) compared. The total germ count is the germ and spore contamination in the refrigerator (1), with high values for bacteria, mold and Yeasts are crucial. It is well known that a variety of mushrooms and Bacteria excretes nitrite. This knowledge allows from a determined nitrite concentration a conclusion on the degree of contamination of the interior (2) of the refrigerator (1) derive. Mushrooms, mold or the like are not always also visually recognizable, but through Nevertheless, biochemical sensors can be recorded directly or indirectly. If the measurement e.g. has high nitrite concentrations, e.g. > 1mg / l, can be simultaneously from one high germ load on the interior (2) can be assumed. The sensor (3) serves indirect germ detection preferably a detection of the metabolic products of Bacteria, yeast and / or mold, e.g. Nitrite concentrations. This turns into nitrite either measured directly or oxidation is used as the measuring method and nitrite Oxidized to nitrate in order to deduce the degree of contamination of the interior (2).

The sensor (3) is on to indicate that cleaning is necessary in good time at least one point of the interior (2) flushed with condensate. For example, arranging the sensor (3) on an evaporator (7) which secures Rear, side wall, ceiling or floor surface can be arranged, good measurement results. Likewise, an arrangement of the sensor (3) in or on a condensate collector is also (8) or in the evaporator dish a sensible place to arrange the sensor. A small change in the interior, between the condensate trap (8) and a drip rail (6) is arranged on the rear wall evaporator (7), creates a place for one Particularly reliable measured value acquisition of the sensor (3). It is advisable to use the sensor (3) to be arranged at the lower end of this drainer (6). It is of particular advantage if the sensor (3) can be replaced. In particular, biochemical sensors should be interchangeable be, because after a certain period of use, depending on the design, exhaust itself. An example of a replaceable sensor is training in Shape of a chip. Also automatic or manually adjustable cleaning of a sensor is useful and, for example, through a brief reversal of potential or increase in potential reachable.

The evaluation electronics (4) are preferably in the electronics already present in the cooling device (1) integrated or arranged in their vicinity. You (4) can also in another place be housed separately. The display element (5) is preferably on the control panel, such as it is known for refrigerators and / or freezers, arranged or in the front area of the Integrated door (10). A control element (11) can also be arranged on the control panel, via which the measuring device (3, 4, 5) is switched off and on manually can be. Switching off should be carried out immediately after cleaning the interior of the cooling unit (1) for a defined period of time to prevent interference with cleaning agent residues be avoided. The measuring device (3, 4, 5) is then either automatic or manually switched on again.

Extensive tests confirm that a currently determined nitrite concentration is reduced to at least half by cleaning the interior (2). The current nitrite concentration is measured by the sensor (3) during flushing with condensate accumulating in the interior, the measurement being carried out at regular or irregular intervals. The measuring distances to the current measured value acquisition can either be determined by the manufacturer or by the user and can be called up via the electronics (4).
A reference limit value for a clean interior (2) of the refrigerator (1) is stored in the evaluation electronics (4), with which each currently recorded value is compared. If this reference limit is exceeded, a warning signal is triggered, which is displayed optically and / or acoustically on a display element, for example. The warning signal is interrupted after a predetermined time, which can also be stored in the electronics (4), and is periodically reactivated. This warning continues until the interior is cleaned or the warning signal is switched off manually. The time interrupt for warning can also interrupt a new, current measurement value acquisition until the interior has actually been cleaned. In addition, it is also possible that the time span between the warnings is shorter than the distances between the individual current measured value acquisitions. Since the bacterial load predominantly increases after advanced time, ie ever higher concentrations of the metabolic products, such as nitrite, are also recorded, a maximum possible concentration can also be stored as a reference limit value in the evaluation electronics (4). When this limit is reached, the warning signal should no longer be suspended. An uninterrupted display is intended to illustrate the advanced level of contamination in order to rule out any health risks when eating the stored food.

However, the user should also be given the option of recording the measured values and / or can turn off a warning if he does not have such information is interested or may even feel bothered by it.

The presence of germs can be measured alongside a measurement of one of the metabolites of bacteria, yeast and / or mold (such as nitrite concentration) directly by biochemical sensing of bacteria, yeast and / or mold or the like determine. Therefore, depending on the target, differently designed sensors (3) can be used, e.g. electrochemical or biochemical sensors.

Other methods, for example a contact with a subsequent incubation, can also be used lead to germ detection. Most users of a household refrigerator (1) are missing however, the knowledge and requirements for carrying out such procedures and Such an effort will certainly find little acceptance among the customer. A copy must be carried out sporadically by hand and require the subsequent measurements Experience in dealing with biochemical processes. Such a possibility for a refrigerator used in the household (1) because of a warning of too high Contamination in the interior (2) cannot take place in good time. The arrangement of a sensor (3) for the automatic and in-service recording of the germs simple and convenient way to indirectly know about the hygienic condition of his Refrigerator (1) to get a quick and orientative statement. A continuously working Sensor (3) ensures a reliable warning if there is any contamination.

FIG. 2 shows a refrigerator (1) whose door (10) hinged on the side is open is shown. The inside of the door (10) contains storage options, in particular for narrow or high refrigerated goods. Also on the inside of the door can in addition to Interior (2), a further sensor (3) for measuring the contamination can be arranged. The The interior (2) is designed in accordance with the cooling device described in FIG. 1. Basically, the moisture on the evaporator collects in the interior (2) and condenses there, icy and melting again. It is therefore an ideal location for the placement of a sensor (3) in the gutter (8) or in the evaporator dish.

Claims (21)

1. Refrigerating apparatus including a device for generating cold, an interior space and a device for collecting condensation created in the interior space, the refrigerating apparatus (1) having a measuring device (3, 4, 5) in the interior space (2) with at least one sensor (3) and one electronic evaluating means (4) for indicating germs and/or spores, characterised in that the sensor (3) is disposed at a location which is flushed-through by condensation from the interior space (2).
2. Refrigerating apparatus according to claim 1, characterised in that the sensor (3) communicates with the electronic evaluating means (4) and/or a displaying element (5).
3. Refrigerating apparatus according to one of claims 1 or 2, characterised in that the sensor (3) is in the form of a biochemical sensor for the selective detection of bacteria, yeast and/or mould.
4. Refrigerating apparatus according to one of claims 1 or 2, characterised in that the sensor (3) is in the form of a biochemical or electrochemical sensor for the detection of metabolic products of bacteria, yeast and/or mould.
5. Refrigerating apparatus according to at least one of claims 1 to 4, characterised in that the sensor (3) is configured for nitrite or nitrate detection.
6. Refrigerating apparatus according to at least one of claims 1 to 5, characterised in that the sensor (3) is disposed in the refrigerating apparatus (1) so as to be removable.
7. Refrigerating device according to at least one of claims 1 to 6, characterised in that the sensor (3) is disposed in the interior space (2) and the electronic evaluating means (4) and/or the displaying element (5) are disposed externally of the interior space (2).
8. Refrigerating apparatus according to at least one of claims 1 to 7, characterised in that the sensor (3) is disposed in or on a condensation-collecting container (8).
9. Refrigerating apparatus according to at least one of claims 1 to 7, characterised in that the sensor (3) is disposed on a rear wall evaporator (7) or in an evaporator shell.
10. Refrigerating apparatus according to at least one of claims 1 to 7, characterised in that a drip bar (6) is disposed between the condensation collecting container (8) and the rear wall evaporator (7) and the sensor (3) is disposed on this drip bar.
11. Refrigerating apparatus according to claim 10, characterised in that an operator element (11) is disposed on the refrigerating apparatus (1) for interrupting the acquisition of the measured data by the measuring device (3, 4, 5).
12. Method of indicating the breeding of germs in a refrigerating apparatus according to at least one of claims 1 to 11, characterised in that the measuring device (3, 4, 5) detects and evaluates, in a selective manner, measured values of bacteria, yeast and/or mould or measured values of at least one of the metabolic products thereof, the measured values being detected via the sensor (3) in definable time intervals and these measured values being compared in the electronic evaluating means (4) with maximum admissible limit values, stored therein, for the breeding of germs and the sensor (3) carrying out the current measured value acquisition during a flushing-through operation with condensation, and in that, when the limit values for the breeding of germs are exceeded by at least one measured value, currently being detected, a signal is passed on to the displaying element (5).
13. Method according to claim 12, characterised in that the amount of germs and/or spores is derivable from the level of the concentration of the metabolic products of bacteria, yeast and/or mould.
14. Method according to one of claims 12 or 13, characterised in that the measured values are measured directly by the sensor (3).
15. Method according to at least one of claims 12 to 14, characterised in that the determining of a nitrite concentration is effected indirectly by means of an electrochemical reaction, where nitrite is oxidised to form nitrate.
16. Method according to at least one of claims 12 to 15, characterised in that the displaying element (5) represents a visual and/or acoustic alarm.
17. Method according to at least one of claims 12 to 16, characterised in that the alarm is interrupted after a time interval, which is shorter than the time interval between the current measuring operations, and in that an alarm is displayed once again after a subsequent measured value acquisition by the sensor (3).
18. Method according to at least one of claims 12 to 16, characterised in that the alarm is displayed in a continuous manner when at least one of the maximum admissible limit values, stored in the electronic evaluating means (4), for the breeding of germs is exceeded.
19. Method according to at least one of claims 13 to 18, characterised in that, after the refrigerating apparatus (1) has been cleaned, the measuring device (3, 4, 5) is switched-off automatically or manually and is switched-on again after a defined period.
20. Method according to at least one of claims 13 to 19, characterised in that after the refrigerating apparatus (1) has been cleaned, the sensor (3) is cleaned.
21. Method according to claim 20, characterised in that a cleaning of the sensor is performed electrochemically by means of potential reversal or potential increase.

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