DE29824137U1 - Temperature control system for a refrigerator - Google Patents

Description

Eisenfuhr, Speiser & Partner ·:·..· : :* : : :: :

• · · · · » ßremei · » ·

European Patent Attorneys
Dipl.-Ing. Günther Eisenführ
Dipl.-Ing. Dieter K. Speiser
Dr.-Ing. Werner W. Rabus
Dipl.-Ing. Jürgen Brügge
Dipl.-Ing. Jürgen Klinghardt
Dipl.-Ing. Klaus G. Göken
Jochen Ehlers
Dipl.-Ing. Mark Andres

Lawyers
Ulrich H. Sander
Sabine Richter

Martinistrasse 24
D-28195 Brennen
Phone +49-(0)421-36 35 0
Fax +49-10)421 -337 8788 (G3)
Fax+49-10)421-328 8631 (G4)
_ _ _{&Lgr;&Agr;&Lgr;&Lgr;} mail@eisenfahrt.com

Bremen, 25 February 2000 Our reference: M 5988 KGG/MAG/cmU

Applicant/Owner: MERLONI ELETTRODOMESTICI Official reference number: New registration

Hamburg

Patent Attorney

European Patent Attorney

Dipl.-Phys. Frank Meier

Lawyers Christian Spintig Rainer Böhm Silja J. Greischel

Munich

Patent attorneys

European Patent Attorneys

Dipl.-Wirtsch.-Ing. Rainer Fritsche

Lbm.-Chem. Gabriele Leißler-Geri

Patent Attorney

Dipl.-Chem. Dr. Peter Schuler

Berlin

Patent attorneys
European Patent Attorneys Dipl.-Ing. Henning Christiansen Dipl.-Ing. Joachim von Oppen Dipl.-Ing. Jutta Kaden

Alicante

European Trademark Attorney Dipl.-Ing. Jürgen Klinghardt

Merloni Elettrodomestici S-P.A., Viale Aristide Merloni, 47.1 - 60044 Fabriano (AN)

Temperature control system for a refrigeration cabinet

The present invention relates to a temperature control system in a multi-compartment refrigerator having a first compartment for storing fresh food, a second compartment for freezing and storing food, a refrigeration circuit comprising a compressor, first and second evaporators arranged in the first and second compartments respectively, and a compressor, and a temperature control circuit.

Refrigerators of the above-mentioned type are already known. In fact, they are probably the most widely used type of household appliance.

Both evaporators, installed respectively in the first compartment (i.e. the cell for storing fresh food or the so-called refrigerator) and in the second compartment ("freezer"), are arranged in series in the same refrigeration circuit, which, for cost reasons, is operated by a single compressor.

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Since both evaporators are arranged in series, the operation of the evaporator assigned to the freezer is mainly controlled by the operation of the evaporator assigned to the refrigerator compartment. The thermostatic control is carried out exclusively with regard to the temperature of the refrigerator compartment.

Such thermostatic control is provided by a standard electromechanical thermostat built directly into the refrigerator compartment, usually provided with a knob for manually setting the desired temperature.

Mainly for this reason, no control system has yet been developed that provides satisfactory operation under changing environmental conditions for both the refrigerator compartment and the freezer compartment. On the other hand, the systems used so far have some problems.

Since the temperature in the refrigerator compartment is usually set at a temperature of 5 ⁰ C, while the working conditions in the freezer compartment are maintained between minus 6 to minus 18 ° C according to the specific freezer design, a refrigeration cabinet is usually manufactured with a freezer compartment followed by the development of the refrigerator compartment, i.e. under normal ambient conditions, the freezer compartment is kept at a temperature lower than the maximum permitted temperature for correctly stored food in order to maintain a safety margin. Therefore, the electrical energy consumption of the refrigeration cabinet will be higher, with a resulting certain uncertainty regarding the temperature value in the freezer compartment. However, to ensure that the temperature in the freezer compartment is well below the maximum permitted temperature for the freezer compartment, the refrigeration cabinet should be installed in a rather cold environment such as a basement, garage or unoccupied holiday home in winter; no thermostat is needed to start the compressor, since the thermal exchange with the outside environment is essentially

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tends to a balanced state. This is the disadvantage of maintaining the temperature in the freezer compartment, which tends to increase the temperature close to the room temperature.

Finally, certain conditions of use for a refrigerator are possible where the known control system is particularly poor. For example, we have such a condition when the use of the refrigerator compartment is not required, for example when people leave the house for a long period of time, i.e. typically when a family leaves the house on vacation. Since the storage of fresh food is no longer necessary, it seems advisable to limit consumption and let only the freezer compartment work efficiently.

However, according to the current state of the art, this is not possible because the cooling circuit is controlled by a thermostat in the refrigerator compartment.

It is an object of the present invention to solve the problems mentioned above and to provide an improved temperature control system in a multi-compartment refrigerator compared to the previously known solutions.

For this purpose, the main object of the present invention is to provide a temperature control system in a multi-compartment refrigerator which also allows operation control as a function of the freezer compartment.

Another object of the present invention is to provide a temperature control system in a multi-compartment refrigerator that can reduce energy consumption under certain usage conditions.

Another object of the present invention is to provide a temperature control system in a multi-compartment refrigerator to improve temperature control in the freezer compartment with respect to room temperature fluctuations.

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To achieve such aims, it is the object of the present invention to provide a temperature control system in a multi-compartment refrigerator, which includes the features of the appended claims forming a part of the description.

Further objects, features and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings, given as a non-limiting example, in which:

Figure 1 schematically shows a temperature control system in a multi-

Refrigeration cabinet according to the present invention, and

Figure 2 schematically shows a temperature control system in a multi-

Refrigeration cabinet according to a second embodiment of the present invention.

Figure 1 shows a refrigeration cabinet with two compartments, a fresh food storage compartment 2 and a freezer compartment 3. The refrigeration cabinet 1 is designed with only one refrigeration circuit 3 comprising a compressor 5, a condenser 6 such as a spiral, a first evaporator E1 installed in the freezer compartment 3, a second evaporator E2 installed in the fresh food compartment 2. The first evaporator E1 and the second evaporator E2 are connected in series within the refrigeration circuit 4 and supplied by condenser 6, so that the refrigeration cycle in both the fresh food storage compartment and the freezer compartment is determined by the activation and deactivation of the individual compressor 5.

Thus, the refrigeration cabinet 1 is equipped with a temperature control circuit 7, which is equipped with a first temperature sensor T1 installed in the fresh food storage compartment and is intended to indicate the fresh food storage compartment temperature 2 to a first thermostat C1, which is also installed in the fresh food storage compartment 2. The first thermostat C1 is then connected to a signal line S1.

Similarly, the freezer compartment 3 has a second temperature sensor T2 which transmits the detected temperature value to a second thermostat C2 which is also installed in the freezer compartment 3. The second thermostat C2 is also connected to a signal line S2.

The signal line S1 and the signal line S2 lead to a switch 8, which can have a position P1 for connecting the signal line S1 to a control line 9 or alternatively a position P2 for connecting the signal line S2 to the control line 9. The control line 9 controls either the activation or the deactivation of the compressor 5.

The operation is as follows: when the fresh food storage compartment 2 either contains food or to maintain a preset accurate average temperature, for example 5°C, inside the compartment, the switch 8 is set to a position P1 and connects the signal line S1 to the control line 9. Accordingly, the first thermostat C1 is able to control activation or deactivation cycles of the compressor 5 through the signal line S1 and the control line 9, based on the values measured by the first temperature sensor T1.

The second thermostat C2 with the corresponding second temperature sensor T2 is not connected during operation.

When precise temperature control within the freezer compartment 3 is required or precise temperature control in the fresh food storage compartment is not required, the user can switch the switch 8 to a position P2, whereby the second thermostat T2 and the associated second temperature sensor T2 are connected to the control line 9 and can control the activation and deactivation cycles of the compressor 5 according to the temperature trend within the freezer compartment 3, whereby the first temperature sensor T1 and the first thermostat T2 are not connected.

Thus, the fresh food storage compartment 2 will follow the temperature development of the freezer compartment 3. Therefore, under certain conditions, such as a low room temperature or a refrigerator with an empty refrigerator compartment 2, the user can switch to a freezer compartment 3 from the cooling control assigned to the fresh food storage compartment 2.

The first temperature sensor T1 and the second temperature sensor T2 as well as the first thermostat C1 and the second thermostat C2 are provided in a known mode of operation, i.e. typically by electromechanical thermostats in which the sensing elements consist of a gas cartridge that expands or contracts according to the temperature, resulting in either a closed or open contact.

Figure 2 shows a second embodiment of the present invention with a different temperature control circuit 10, which has a first sensor T1 and a second sensor T2, which supply the measured temperature values to the input terminals 11 and 12 of an electronic thermostat C via signal lines S1 and S2. The electronic thermostat C also has an output terminal U, which is connected to the control line 9 for controlling the compressor 5. A selector 11 on the electronic thermostat C makes it possible to distinguish whether the temperature value supplied by the first temperature sensor 2 or the temperature value supplied by the second temperature sensor T2 should be used.

The temperature control circuit 10 also allows to add another control function without any difficulty. If a thermostatic control is applied to the freezer compartment 3, there may be a risk that the compressor 5 will remain active for a very long period of time at specific high room temperatures. As a result, the temperature in the refrigerator compartment may drop to considerably low values, even below 0°C. This may possibly

cause the contents of bottles not removed from the refrigerating compartment to freeze and ice formation to occur on the walls of the refrigerating compartment. The first temperature sensor T1 always remains physically and electrically connected through the temperature control circuit 10 to the input terminal 11 of the electronic thermostat C, to which the measured temperature is fed, even when the electronic thermostat C is not using it to manage the compressor 5. The electronic thermostat can, however, be programmed to activate an emergency sequence to prevent the temperature in the fresh food storage compartment from falling below 0°C, for example by increasing the temperature in the refrigerating compartment by activating a suitable electrical resistance.

The features of the present invention and its advantages are made clear from the above description.

The temperature control system in a multi-compartment refrigerator described above by way of example advantageously allows thermostatic control according to a selection of either the temperature in the refrigerator compartment or the temperature in the freezer compartment. Firstly, this involves the possibility of a more cost-efficient consumption rate since the selection of thermostatic control with respect to the freezer compartment removes any unnecessary cycles due to a temperature change in the refrigerator compartment.

A thermostatic control related to the freezer compartment can be specifically selected when temperature control of the refrigerator compartment is not necessary, for example when such a refrigerator compartment is emptied when leaving the house for a certain period of time, for example during holidays.

The temperature control system in a multi-compartment refrigerator according to the present invention is particularly suitable for use in holiday homes or in special residential areas.

are advantageous in the mountains, where they are often not used for long periods of time and in these cases the refrigerator compartment must be completely emptied. In this case the power connections of the refrigerator are usually disconnected, as repeated compressor cycles make it costly to leave the refrigerator running.

The refrigerator door must be left open to avoid possible mold formation inside the compartment. Choosing a thermostatic control for the freezer compartment, on the other hand, allows long-lasting foods to be stored inside the freezer compartment at a much lower cost. Furthermore, the number of cooling cycles ensured by the thermostatic control of the freezer compartment is enough to prevent mold formation inside the refrigerator compartment. Furthermore, the temperature control system according to the present invention also allows to solve the problem of low room temperature in holiday homes in the mountains as mentioned above, which occurs because people turn off the heating or set it at a very low level when they are out.

Furthermore, the temperature control system in a multi-compartment refrigerator according to the present invention advantageously allows precise temperature control within the freezer compartment to prevent a temperature rise when the external temperature is too low with respect to the requirement for the freezer compartment to demand the required number of refrigeration cycles but enough to maintain the desired temperature within the freezer compartment.

Obviously, many changes are possible for those skilled in the art of temperature control systems in a multi-compartment refrigerator described by way of example, without departing from the spirit of novelty of the inventive solution, and it is also clear that in the practical implementation of the invention, the components may often differ in shape and size from those described here and may be replaced by technically equivalent elements.

For example, the temperature sensors may be of any type available for the temperature range of refrigerators, and they may or may not be part of the temperature control management components.

The selector can be installed inside or outside the refrigeration cabinet, either in the form of a button or a rotary knob, and the selection of the thermostatic control can also be achieved by remote control and/or by a control unit separate from the refrigeration cabinet.

A possible embodiment of the present invention may comprise an electronic thermostat with a microprocessor and a memory means, such as programmed according to the known principles of fuzzy logic, to allow automatic switching of the thermostatic control according to programs implemented by the manufacturer, for example by transferring the operating control of the refrigeration circuit to that of the thermostat associated with the freezer compartment once all the cooling cycles are controlled by the thermostat associated with the refrigerator compartment, or according to a program that learns the habits of the user.

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Claims (13)

1. Temperature control system in a multi-compartment refrigeration cabinet, the refrigeration cabinet comprising:
a first compartment for storing fresh food,
a second compartment for freezing and storing food,
a refrigeration circuit comprising a compressor, a first and a second evaporator, each arranged in the first and second compartments, and a condenser, and
a temperature control circuit, characterized in that the temperature control circuit (7, 10) comprises a first temperature sensor (T1) installed in the fresh food storage compartment (2) and a second temperature sensor (T2) installed in the food freezing and storage compartment (3), a selection means (8, 11) for activating a sensor which selects between the first temperature sensor (T1) and the second temperature sensor (T2), which controls the control of the operation of the refrigeration circuit (4) by control means (C1, C2, C) included in the temperature control circuit (7, 10). 2. Temperature control system in a multi-compartment refrigerator according to claim 1, characterized in that the selection means (8, 11) comprises a switch. 3. Temperature control system in a multi-compartment refrigerator according to claim 2, characterized in that the switch (8) is a manual switch. 4. Temperature control system in a multi-compartment refrigerator according to claim 3, characterized in that the control means (C1, C2) represent thermostatic control circuits. 5. Temperature control system in a multi-compartment refrigerator according to claim 1, characterized in that the selection means (11) and the control means (C) are included in an electronic thermostat. 6. Temperature control system in a multi-compartment refrigerator according to claim 5, characterized in that the electronic thermostat (C) is programmed to activate a sequence for increasing the temperature in the fresh food storage compartment (2) when the temperature in the fresh food storage compartment (2) falls below a preset value. 7. Temperature control system in a multi-compartment refrigerator according to claim 6, characterized in that the electronic thermostat (C) activates a heating element for increasing the temperature in the fresh food storage compartment (2) when the temperature in the fresh food storage compartment (2) falls below a preset value. 8. Temperature control system in a multi-compartment refrigerator according to claim 6, characterized in that an electronic thermostat (C) comprises a microprocessor and storage means for carrying out preset control programs of the thermostatic control. 9. Temperature control system in a multi-compartment refrigerator according to claim 8, characterized in that the preset control programs of the thermostatic control provide for switching from the first temperature sensor (T1) to a second temperature sensor (T2) every n cycles. 10. An apparatus for carrying out a temperature control method in a multi-compartment refrigerator having a first compartment for storing fresh food, a second compartment for freezing and storing food, a refrigeration circuit having a compressor, first and second evaporators arranged in the first and second compartments respectively, and a condenser; and a temperature control circuit, wherein the user can perform thermostatic control with respect to the temperature of the selected compartment (2, 3) by operating a specific switch (8, 11) which activates thermostatic control with respect to a temperature value supplied by the temperature sensor (T1, T2) installed in the compartment (2, 3) selected by the user when temperature control is to be performed in one of the two compartments (2, 3). 11. An apparatus for carrying out a temperature control method in a multi-compartment refrigerator according to claim 10, wherein means (C) are provided in the temperature control circuit (7, 10) for starting a temperature increase process in the compartment when the temperature in one of the compartments (2, 3) falls below a preset value. 12. An apparatus for carrying out a temperature control method in a multi-compartment refrigerator according to claim 10, wherein means are provided in the temperature control circuit (7, 10) for starting a temperature increase process in the compartment when the temperature in one of the compartments (2, 3) falls below a preset value. 13. An apparatus for carrying out a temperature control method in a multi-compartment refrigerator according to claim 10, characterized in that switching from the first temperature sensor (T1) to the second temperature sensor (T2) occurs automatically on the basis of a management program of the refrigerator.