Refrigeration device and method for operating a refrigeration device

Abstract

A method for operating a refrigeration appliance comprises detecting an actual temperature in a storage space of the refrigeration appliance extending in a vertical direction, which storage space has a refrigeration compartment and a cold storage compartment located below the refrigeration compartment in relation to the vertical direction, supplying an evaporator thermally coupled to the storage space with refrigerant in order to extract heat from the storage space when the actual temperature reaches or exceeds a first temperature threshold, interrupting the supply of refrigerant to the evaporator when the actual temperature reaches or falls below a second temperature threshold that is lower than the first temperature threshold, operating a fan positioned in the refrigeration compartment of the storage space to generate air circulation within the storage space when the actual temperature reaches or exceeds a third temperature threshold that is higher than the first temperature threshold,and stopping the operation of the fan when the actual temperature reaches or falls below a fourth temperature threshold that is less than the first temperature threshold and greater than or equal to the second temperature threshold.

Description

TECHNICAL FIELD

[0001] The present invention relates to a refrigeration appliance, in particular a household refrigeration appliance such as a refrigerator, a freezer or a freezer chest or a fridge-freezer combination, and a method for operating a refrigeration appliance. STATE OF THE ART

[0002] In household refrigeration appliances, refrigerated goods are stored in a storage room from which heat is extracted with the help of a refrigerant circuit through evaporation of refrigerant in order to cool the refrigerated goods. Refrigerated goods with different storage requirements are usually stored in the storage room. In order to meet the different requirements, for example with regard to storage temperature, the storage room is often divided into a refrigerated compartment and a so-called cold storage compartment. Both the refrigerated compartment and the cold storage compartment are cooled by a common evaporator. Due to natural convection within the storage room, temperature stratification occurs, with an area near the floor or below being cooler than an area higher up. This effect is used to create a lower temperature in the cold storage compartment than in the refrigerated compartment.

[0003] DE 10 2019 216 649 A1, for example, describes a household refrigeration appliance whose storage space is divided into a refrigerated compartment and a cold storage compartment. Furthermore, a fan is provided in the storage space to drive air circulation within the storage space. The fan is switched on and off simultaneously or with a slight time delay to a compressor, which supplies refrigerant to an evaporator cooling the storage space. During operation of the fan, temperature differences within the storage space are significantly reduced, which can lead to a required temperature difference between the cold storage compartment and the refrigerated compartment being undercut, at least during fan operation. SUMMARY OF THE INVENTION

[0004] It is one of the objects of the present invention to provide improved solutions for operating a refrigeration appliance, in particular solutions with which a desired temperature difference can be maintained in different zones of a storage room of the refrigeration appliance in as many operating situations as possible.

[0005] This object is achieved according to the invention by a method having the features of claim 1 and by a refrigeration device having the features of claim 10.

[0006] Advantageous embodiments and further developments arise from the subclaims which refer back to the independent claims in conjunction with the description.

[0007] According to a first aspect of the invention, a method for operating a refrigeration appliance comprises detecting an actual temperature in a storage space of the refrigeration appliance which extends in a vertical direction and has a refrigeration compartment and a cold storage compartment located below the refrigeration compartment in relation to the vertical direction, supplying an evaporator which is thermally coupled to the storage space with refrigerant in order to extract heat from the storage space when the actual temperature reaches or exceeds a first temperature threshold, interrupting the supply of refrigerant to the evaporator when the actual temperature reaches or falls below a second temperature threshold which is lower than the first temperature threshold, operating a fan positioned in the refrigeration compartment or main storage compartment of the storage space in order to create a directed air flow orTo generate air circulation within the storage room when the actual temperature reaches or exceeds a third temperature threshold, which is greater than the first temperature threshold, and to stop the operation of the fan when the actual temperature reaches or falls below a fourth temperature threshold, which is lower than the first temperature threshold and greater than or equal to the second temperature threshold. After the fan stops, a temperature distribution is established in the storage room due to natural convection, in which the actual temperature in the cold storage compartment is lower than in the refrigerated compartment, in particular due to the lower positioning of the cold storage compartment in relation to the vertical direction.

[0008] According to a second aspect of the invention, a refrigeration appliance is provided, in particular a household refrigeration appliance, such as a refrigerator, a freezer or a fridge-freezer combination. The refrigeration appliance according to the invention comprises a storage space extending in a vertical direction, which has a refrigeration compartment and a cold storage compartment located below the refrigeration compartment with respect to the vertical direction, a refrigerant circuit with an evaporator thermally coupled to the storage space in order to extract heat from the storage space by supplying the evaporator with refrigerant, a fan arranged in the refrigeration compartment, which is designed to generate air circulation within, a temperature sensor connected to the storage space, which is designed to detect an actual temperature in the storage space, and a control device which is signal-connected to the temperature sensor, the refrigerant circuit and the fan.The control device is designed to operate the refrigeration appliance according to a method according to the first aspect of the invention.

[0009] One idea underlying the invention is to operate the fan as needed depending on the actual temperature in the storage room and thereby shorten the operating times of the fan in order to maintain a temperature stratification or distribution resulting from natural convection in as many operating situations as possible.

[0010] The storage space is divided vertically, which may be parallel to the direction of gravity when the refrigeration appliance is in normal operation, for example, into a refrigerated compartment and a cold storage compartment. The cold storage compartment is positioned lower than the refrigerated compartment in relation to the vertical direction. When the refrigeration appliance is in operation, the temperature in the cold storage compartment should be lower than in the refrigerated compartment. For example, it can be provided that there should be a predetermined temperature difference between the refrigerated compartment and the cold storage compartment, which can be in a range of 1 to 4 Kelvin, for example. Both the refrigerated compartment and the cold storage compartment are cooled together by the same evaporator in the refrigerant circuit.

[0011] A fan is installed in the storage room, specifically in the refrigerated compartment. When the fan is running, air circulation occurs within the storage room. This air circulation creates forced convection, which promotes heat transfer from the storage room to the evaporator. At the same time, the air circulation ensures a relatively homogeneous temperature distribution within the storage room. When the fan is not running, natural convection generally creates temperature stratification, with the actual temperature in the lower area of the storage room, where the cold storage compartment is located, being lower than in the upper area of the storage room.

[0012] According to the invention, the storage room is cooled by the evaporator when the actual temperature in the storage room reaches or exceeds a first temperature threshold or a first temperature limit. However, the fan is only activated when the actual temperature reaches or exceeds a third temperature threshold or a third temperature limit that is higher than the first temperature limit. This means that the fan is only operated when there is a significant additional heat input into the storage room, e.g. when warm refrigerated goods are placed in the storage room and / or a door that closes the storage room is opened for an extended period of time. If the first temperature threshold is exceeded by such a small amount that the actual temperature does not reach the third temperature limit, the fan is not activated.Fan operation is stopped when the actual temperature reaches or falls below a fourth temperature threshold. The fourth temperature threshold can be greater than or equal to a second temperature threshold at which refrigerant supply to the evaporator is stopped.

[0013] This allows the temperature distribution established by natural convection to be maintained even if the actual temperature exceeds the first temperature limit by small amounts. A further advantage is that taking the actual temperature into account when activating and deactivating the fan reduces the fan's operating time. This reduces the refrigeration appliance's energy consumption.

[0014] According to some embodiments, the fourth temperature threshold may be greater than the second temperature threshold. Accordingly, the fan is deactivated before the refrigerant supply to the evaporator is stopped. Consequently, the fan's operating time can be further shortened.

[0015] According to some embodiments, the method additionally comprises detecting an ambient temperature and determining the third temperature threshold and / or the fourth temperature threshold depending on the ambient temperature. This means that an activation and deactivation temperature, at which the fan is activated or stopped, can be adapted to the current ambient temperature. For example, it can be provided that the control device of the refrigeration appliance accesses a look-up table in which a plurality of temperature ranges of the ambient temperature and a plurality of third and / or fourth temperature thresholds are stored in such a way that a third and / or a fourth temperature threshold is assigned to each temperature range of the ambient temperature. The actual temperature and thus also the natural convection in the storage room are influenced by the ambient temperature.By taking into account the actual temperature and adjusting the activation and deactivation temperature to activate and deactivate the fan, an even more targeted influence on the temperature distribution in the storage room is possible in such a way that the temperature difference between the refrigerated compartment and the cold storage compartment is kept within predetermined limits in as many operating situations as possible.

[0016] According to some embodiments, the third temperature threshold can be determined depending on the ambient temperature such that a first temperature difference between the first temperature threshold and the third temperature threshold decreases as the outside temperature increases. Accordingly, at high outside temperatures, the fan is activated even when the first temperature limit is only slightly exceeded. This increases the cooling capacity, and the temperature in the storage room can be reduced more quickly.

[0017] According to some embodiments, the fourth temperature threshold can be determined depending on the ambient temperature such that a second difference between the second temperature threshold and the fourth temperature threshold decreases as the outside temperature increases. Accordingly, at high outside temperatures, the temperature at which the fan is deactivated is lowered. This ensures faster cooling of the storage room to the desired temperature, while still avoiding an unnecessarily long fan runtime.

[0018] According to some embodiments, it may be provided that a difference between the first temperature threshold value and the second temperature threshold value lies in a range between 0.25 and 3 Kelvin.

[0019] According to some embodiments, it may be provided that a difference between the first temperature threshold value and the second temperature threshold value lies in a range between 0.25 and 1.5 Kelvin.

[0020] According to some embodiments, the third temperature threshold may be up to 4 K higher than the first temperature threshold. The third temperature threshold may, for example, be at least 0.25 K and at most 4 K higher than the first temperature threshold. Accordingly, the fan may only be activated when the actual temperature in the storage room exceeds the first temperature threshold by at least 4 K.

[0021] According to some embodiments, the evaporator may be supplied with refrigerant by means of a compressor, and the fan may only be operated when the compressor supplies the evaporator with refrigerant. This means that the fan is only operated to cool the storage space when the evaporator is also supplied with refrigerant. An exception to this may be defrosting the storage space, as explained below.

[0022] According to some embodiments, the method may additionally comprise detecting a defrost signal and performing a defrost process when the defrost signal is detected, regardless of the detected actual temperature. The defrost process may comprise interrupting the supply of refrigerant to the evaporator and operating the fan for a predetermined period of time. The defrost signal may be detected, for example, by the control device. For example, the control device may determine a cumulative operating time during which the evaporator was supplied with refrigerant and detect a defrost signal when the cumulative operating time reaches a predetermined limit. By interrupting the supply of refrigerant to the evaporator and simultaneously operating the fan, an effective heat input into the storage space takes place, whereby ice that has formed in the area of the evaporator is quickly defrosted.

[0023] According to some embodiments, the storage space can be delimited vertically by a floor and a ceiling opposite the floor, with the cold storage compartment being positioned in an end region of the storage space facing the floor. During intended use of the refrigeration appliance, e.g., when carrying out the method according to the invention, the cold storage compartment is thus located below the refrigerated compartment with respect to the direction of gravity.

[0024] According to some embodiments, the storage space may be delimited by a rear wall in relation to a depth direction, and the evaporator may be arranged on a side of the rear wall facing away from the storage space. For example, the evaporator may be in heat-conducting contact with an outer surface of the rear wall. Further optionally, the evaporator may be surrounded by a thermal insulation material on its sides not in contact with the rear wall. In general, the evaporator may be a rear-wall evaporator.

[0025] According to some embodiments, the evaporator may be arranged without a fluidic connection to the storage space. Unlike so-called NoFrost refrigeration devices, in which air circulation takes place between the storage space and an evaporator chamber in which the evaporator is housed, the evaporator according to the present embodiment is arranged outside the storage space and without a fluidic connection to it.

[0026] According to some embodiments, the cold storage compartment may be vertically separated from the refrigerated compartment by an intermediate floor. The intermediate floor may, for example, extend between two side walls opposite each other in a transverse direction and be arranged at a distance from the floor of the storage space. The intermediate floor may, for example, be designed as a glass plate. In general, the intermediate floor helps to reduce air exchange between the refrigerated compartment and the cold storage compartment, making it easier to maintain the desired temperature difference.

[0027] According to some embodiments, it may be provided that the temperature sensor is connected to the cooling compartment in order to detect a temperature in the cooling compartment as the actual temperature of the storage room.

[0028] The features and advantages disclosed herein in connection with one aspect of the invention are also disclosed for the other aspect and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The invention is explained below with reference to the figures of the drawings. The figures show: Fig. 1 shows a simplified, schematic sectional view of a refrigeration device according to an embodiment of the invention; Fig. 2 shows a flow diagram of a method according to an embodiment of the invention; Fig. 3 shows a diagram in which a temporal profile of an actual temperature in the storage room of a refrigeration device is shown together with activation states of a fan and a refrigerant supply to an evaporator during the implementation of a method according to an embodiment of the invention; Fig. 4 shows a diagram in which a temporal profile of an actual temperature in the storage room of a refrigeration device is shown together with activation states of a fan and a refrigerant supply to an evaporator during the implementation of a method according to a further embodiment of the invention; and Fig.5 a diagram in which a temporal progression of an actual temperature in the storage room of a refrigeration appliance is shown together with activation states of a fan and a refrigerant supply to an evaporator as well as a defrost signal during the implementation of a method according to a further embodiment of the invention. .

[0030] In the figures, the same reference symbols denote identical or functionally identical components, unless otherwise stated. DETAILED DESCRIPTION OF EMBODIMENTS

[0031] Fig. 1 shows, by way of example, a refrigeration appliance 100 in the form of a refrigerator. However, the invention is not limited thereto. The refrigeration appliance 100 can also be designed, for example, as a freezer or a refrigerator-freezer combination, or generally as a household refrigeration appliance.

[0032] As in Fig. 1 Shown by way of example and only schematically, the refrigeration appliance 100 has a storage space 10, a refrigerant circuit 2, a fan 3, a sensor system 4 and a control device 5.

[0033] The storage space 10 can, for example, be delimited by an inner container 1, which is part of a body 110 of the refrigeration device 100. The inner container 1 can have a base 1A, a ceiling 1B opposite thereto in a vertical direction V, a rear wall extending in the vertical direction V between the base 1A and the ceiling 1C and delimiting the storage space 5 with respect to a depth direction T, and opposing side walls 1D extending in the vertical direction V between the base 1A and the ceiling 1C and delimiting the storage space 5 with respect to a transverse direction C. The depth direction T extends transversely to the vertical direction V. The transverse direction extends transversely to the vertical direction V and to the depth direction T. The storage space 10 extends generally in the vertical direction V. As in Fig. 1 As shown, the refrigeration appliance 100 can be oriented when used as intended so that the vertical direction V runs parallel to the direction of gravity G. The base 1A is thus arranged at the bottom with respect to the vertical direction.

[0034] The side walls 10, the floor 1A and the ceiling 1B together define an access opening through which the storage space 5 is accessible and which can be closed by means of a door 115. As in Fig. 1 As further shown, the body may comprise an insulating material 112 which encloses the inner container 1.

[0035] As in Fig. 1 Schematically shown, the storage space 10 is divided into a refrigerated compartment 11 and a cold storage compartment 12 with respect to the vertical direction V, e.g., by an intermediate floor 13 extending along the depth direction T. Furthermore, the intermediate floor 13 can extend, for example, between the side walls 1D in the transverse direction C. The intermediate floor 13 can be, for example, a glass plate. The cold storage compartment 12 is located below or lower than the refrigerated compartment 11 with respect to the vertical direction V. The cold storage compartment 12 can, for example, be located in an end region of the storage space 1 facing the floor 1A, as in Fig. 1 shown as an example.

[0036] The refrigerant circuit 2 is in Fig. 1 shown only schematically and comprises an evaporator 20, a compressor 21, a condenser 22 and a throttle device (not shown).

[0037] The evaporator 20 is thermally coupled to the storage space 10 in order to extract heat from both the refrigerated compartment 11 and the cold storage compartment 12 by evaporating refrigerant. As shown in Fig. 1 As shown schematically, the evaporator 20 can be designed as a rear wall evaporator. Here, the evaporator 20 is arranged on a side of the rear wall 1C facing away from the storage space 10. Preferably, the evaporator 20 is in heat-conducting contact with the outside of the rear wall 1C. Further optionally, the evaporator 20 can be surrounded by the insulating material 112 on its free surfaces that are not in heat-conducting contact with the rear wall 1C. The evaporator 20 can generally be arranged without a fluidically conductive connection to the storage space 10.

[0038] An outlet of the evaporator 20 is connected to a suction port of the compressor 21. An inlet of the condenser 22 is connected to a pressure port of the compressor 21. The compressor 21 sucks in the gaseous refrigerant evaporated in the evaporator 20, compresses it, and feeds it to the condenser 22, where it condenses, releasing heat to the environment. An outlet of the condenser 22 is connected to an inlet of the evaporator 20, and the throttling element, e.g. in the form of a capillary or an expansion valve, is arranged between the condenser 22 and the evaporator 20. The refrigerant condensed in the condenser 22 is expanded in the throttling element and fed back to the evaporator 20.

[0039] Fan 3 is in Fig. 1 shown only schematically and arranged in the storage room 10, in particular in the refrigerated compartment 11. In general, the fan 3 is arranged and designed to generate air circulation within the storage room 1. By operating the fan 3, forced convection can be achieved on the rear wall 1C in order to promote heat exchange between the storage room 10 and the evaporator 20. At the same time, the air circulation achieves a relatively homogeneous temperature distribution within the storage room 10. When the fan 3 is not operated, a temperature distribution within the storage room 10 is established due to natural convection, in which the temperature in the cold storage compartment 12 is lower than in the refrigerated compartment 11, since the cold storage compartment 12 is located below the refrigerated compartment 11. This can be used to create temperature zones with different temperatures within the storage room 10, e.g.to better meet the different storage requirements for different types of refrigerated goods.

[0040] The sensor system 4 comprises a temperature sensor 41, which is arranged to detect an actual temperature in the storage room 10. As in Fig. 1 As shown schematically, the temperature sensor 41 can be connected, for example, to the cooling compartment 11 in order to detect the temperature in the cooling compartment 11. As shown in Fig. 1 Also shown, the sensor system 4 may additionally comprise an optional ambient temperature sensor 42, which is arranged to detect the ambient temperature outside the storage space 5.

[0041] The control device 5 is in Fig. 1 shown only as a block and can, for example, be an electronic control device. For example, the control device 5 can have a non-volatile data memory (not shown) and a processor (not shown). The data memory can be readable by the processor and store software that can be executed by the processor. The data memory can, for example, be an EEPROM, a flash memory, an SD memory, a magnetic memory, or the like. The processor can, for example, have a CPU, an FPGA, an ASIC, or the like. In general, the control device 5 is designed to receive input signals and to output control signals based on the input signals.

[0042] As in Fig. 1 As shown schematically, the control device 5 is signal-connected to the fan 3, the sensor system 4 and the refrigerant circuit 2, in particular the compressor 21, e.g. via a data bus. The control device 5 is designed to control the refrigeration device 100 according to a method described below with reference to the Fign. 2 bis 5 described method M. In general, the control device 5 can generate a control signal to cause the compressor 21 to supply the evaporator 21 with refrigerant, so that heat is extracted from the storage space 10. Furthermore, the control device 5 can also generate a control signal to operate or activate the fan 3, whereby air is circulated in the storage space 10, as described above. The control device 5 receives as input signals the actual temperature in the storage space detected by the temperature sensor 41 and, if applicable, the ambient temperature detected by the ambient temperature sensor 42. Furthermore, the control device 5 can optionally determine a defrost signal.

[0043] The method M for operating the refrigeration device 100 is described below with reference primarily to the Fign. 2 and 3 explained. Fig. 2 shows a schematic flow diagram of the method M. Fig. 3 shows a schematic time-temperature diagram in which a line Ta represents the actual temperature in the storage room 10 over time t. Furthermore, Fig. 3 A signal S1 is plotted over time t, and a signal S2 is plotted over time t. Signal S1 represents a supply of refrigerant to the evaporator 20. A value of signal S1 of "1" means that refrigerant is supplied to the evaporator 20, while a value of "0" means that the supply of refrigerant to the evaporator 20 is stopped or interrupted. Signal S2 represents the operating state of the fan. A value of "1" means that fan 3 is operating or activated, while a value of "0" means that the operation of fan 3 is interrupted or stopped.

[0044] As in Fig. 2 As shown schematically, the control device 5 can optionally determine in a first query step D0 whether a defrost signal is detected. If this is the case, as shown in Fig. 2 represented by the symbol "+", a defrost process M7 is carried out, which is explained below. Otherwise, as in Fig. 2 represented by the symbol "-", the process M proceeds to step M1.

[0045] In step M1, the actual temperature in storage room 10 is detected using temperature sensor 41. In the optional step M11, the ambient temperature is detected using ambient temperature sensor 42. In the equally optional step M12, the control device 5 can determine a third temperature threshold and / or a fourth temperature threshold depending on the ambient temperature. This will be explained in more detail below.

[0046] In query step D1, the recorded actual temperature in the storage room 10 is compared with a first temperature threshold T1. If the actual temperature reaches or exceeds the first temperature threshold, as in Fig. 2 represented by the symbol "+", the process proceeds to step M2. Otherwise, as shown in Fig. 2 shown by the symbol "-", the process M goes back to step M1.

[0047] In step M2, the evaporator 20 is supplied with refrigerant to extract heat from the storage room 10. As in Fig. 3 As can be seen, the actual temperature Ta reaches the first temperature threshold T1 at time t31. The signal S1 changes from the value "0" to "1." This means that the control device 5 outputs a control signal to supply the evaporator 20 with refrigerant, e.g., by activating the compressor 21 through the control signal.

[0048] In a further query step D2, the actual temperature is compared with a third temperature threshold. If the actual temperature reaches or exceeds a third temperature threshold. The third temperature threshold is in Fig. 3 It is shown as temperature T3 and is generally higher than the first temperature threshold. For example, the third temperature threshold can be up to 4 K higher than the first temperature threshold.

[0049] If it is determined in step D2 that the actual temperature is less than the third temperature threshold, as in Fig. 2 represented by the symbol "-", the method proceeds to comparison step D4. In step D4, the actual temperature is compared with a second temperature threshold. The second temperature threshold is Fig. 3 It is shown as temperature T2 and is generally lower than the first temperature threshold. For example, the second temperature threshold can be between 0.25 and 3 Kelvin, in particular between 0.25 and 1.5 Kelvin, lower than the first temperature threshold.

[0050] If the second temperature threshold T2 is reached or undercut, as in Fig. 2 represented by the symbol "+" at step D4, the method M proceeds to step M5. Otherwise, as shown in Fig. 2 At step D4, represented by the symbol "-", the method M returns to step M2. In step M5, the supply of refrigerant to the evaporator 20 is interrupted or stopped. For example, the control device 5 can stop outputting the control signal for operating the compressor 21.

[0051] As in Fig. 3 As shown schematically, after time t31, at which the second temperature threshold is reached and the supply of refrigerant to the evaporator 20 is initiated, the actual temperature Ta briefly continues to rise due to the transient nature of the heat dissipation from the storage space 10, before falling due to the heat dissipation via the evaporator 20 until it reaches the second temperature threshold t32 at time t32. At this time, the signal S1 changes from the value "1" to "0" according to step M5 of method M. This means that the supply of refrigerant to the evaporator 20 is stopped.

[0052] As in Fig. 3 As can be seen further, the temperature rises again after time t31, after a small undershoot, and reaches the first temperature threshold T1 again at time t33. In step D1, it is therefore determined that the actual temperature is greater than or equal to the first temperature threshold and the supply of refrigerant to the evaporator 20 is reactivated (step M2), as in Fig. 3 This can be seen by the fact that signal S1 changes from "0" to "1" again. The actual temperature Ta continues to rise after time t33, e.g., due to a large heat input into storage room 10. This can be the case, for example, if larger quantities of warm refrigerated goods are placed in storage room 5 and / or if door 115 is opened for an extended period of time.

[0053] As in Fig. 3 As shown, the actual temperature Ta reaches the third temperature threshold T3 at time t34. The comparison step D3 thus shows that the actual temperature is greater than or equal to the third temperature threshold ( Fig. 2 , symbol "+" at D2) and the method M proceeds to step M3. In step M3, the fan 3 is operated to generate air circulation within the storage room 1. For example, the control device 5 can output a control signal to the fan 3 to activate it. In Fig. 3 This is shown schematically by the fact that at time t33 the value of signal S2 changes from "0" to "1".

[0054] The operation of fan 3 ensures forced convection on the walls 1A, 1B, 1C, 1D of storage space 10 and thus promotes heat transfer to the refrigerant flowing in the evaporator 20. After a brief further increase, the actual temperature Ta in storage space 10 begins to fall after time t33. During operation of fan 3, the circulation of the air within storage space 10 results in a relatively homogeneous temperature distribution, which can, at least temporarily, lead to a desired temperature difference between the actual temperature in refrigerated compartment 11 and the actual temperature in cold storage compartment 12 being undershot, and the temperatures in refrigerated compartment 11 and in the cold storage compartment approaching.

[0055] Again with reference to Fig. 2 After step M2, the comparison step D3 is carried out, in which the actual temperature is compared with a fourth temperature threshold value. Fig. 3 The fourth temperature threshold is indicated as temperature T4. Generally, the fourth temperature threshold is greater than or equal to the second temperature threshold. Preferably, the fourth temperature threshold is greater than the second temperature threshold. Furthermore, the fourth temperature threshold is less than the first temperature threshold.

[0056] If it is determined in step D3 that the actual temperature is greater than the third temperature threshold, as in Fig. 2 represented by the symbol "-", the process returns to step M3 and the fan 3 continues to operate. If it is determined in step D3 that the actual temperature reaches or falls below the fourth temperature threshold, as in Fig. 2 represented by the symbol "+", the method M proceeds to step M4, in which the operation of the fan 3 is stopped, e.g. by the control device 5 interrupting the output of the control signal for operating the fan 3.

[0057] In Fig. 3 the actual temperature Ta reaches the fourth temperature threshold T4 at time t35. Accordingly, the signal S2 changes its value from "1" to "0" at time t35, and the operation of the fan 3 is stopped. However, the evaporator 20 continues to be supplied with refrigerant because the actual temperature Ta is still above the second temperature threshold T2. After the fan 3 stops, forced convection no longer takes place in the storage room 10. Therefore, after the fan 3 stops, the temperature distribution within the storage room 10 is again determined by natural convection, and a temperature distribution can quickly be established in which the actual temperature in the cold storage compartment 12 is lower than in the refrigerated compartment 11, in particular lower by a predetermined value, e.g., by at least 1 Kelvin.

[0058] As already mentioned above, in step M 12 the third and / or fourth temperature threshold can be determined depending on the ambient temperature. Fig. 3 For example, a first temperature difference dT1 is shown, which corresponds to a difference between the first temperature threshold and the third temperature threshold. Fig. 3 a second temperature difference dT2 is shown, which corresponds to a difference between the second temperature threshold and the fourth temperature threshold. Optionally, it can be provided that the third temperature threshold is determined depending on the ambient temperature in such a way that the first temperature difference decreases with increasing outside temperature. Likewise, it can be provided that the fourth temperature threshold is determined depending on the ambient temperature in such a way that the second difference decreases with increasing outside temperature. This is exemplified in Fig. 4 which shows that the temperature differences dT1, dT2 compared to Fig. 3 This means that the third temperature threshold T3 is closer to the first temperature threshold T1 and thus at a lower temperature than in Fig. 3 . Similarly, the fourth temperature threshold T4 is closer to the second temperature threshold T2 and thus also at a lower temperature than in Fig. 3 . Consequently, fan 3 is started at time t41 (step M3), shortly after time t31, at which the supply of refrigerant to compressor 20 begins (step M2). Furthermore, fan 3 is not deactivated until time t42, and thus shortly before the supply of refrigerant to compressor 20 is stopped at time t32 (step M5). As shown in Fig. 4 indicated by the hatched areas A, the operating time of fan 3 is compared to Fig. 3 thus extended to accelerate the heat dissipation, which is slower at high ambient temperatures.

[0059] As can be seen from the process Fig. 2 results and in Fig. 3 As illustrated by the signals S1 and S2, operation (step M3) of the fan 3 only occurs when the compressor 21 supplies the evaporator 21 with refrigerant. An exception to this occurs when the presence of a defrost signal is detected in step D0, as in Fig. 2 represented by the symbol "+". In this case, the method proceeds to a defrosting process M7. For example, the control device 5 can determine a cumulative operating time during which the evaporator 20 was supplied with refrigerant and detect a defrosting signal when the cumulative operating time reaches a predetermined limit. Fig. 5 The defrost signal is shown as signal S6. As shown in Fig. 5 As shown, at time t51 the defrost signal is detected and the signal S6 changes its value from "0" to "1" accordingly. Immediately before time t51 in the example of Fig. 5 the actual temperature Ta is below the second temperature threshold T2, which is why both the operation of fan 3 is stopped and the supply of refrigerant to evaporator 20 is interrupted (signals S1 and S2 equal to "0"). At time t51, the defrosting process M7 begins, regardless of the detected actual temperature. If not already interrupted, as in the example of Fig. 5 , in step M71, the supply of refrigerant to the evaporator 20 is interrupted, in particular for a predetermined period of time, e.g., until the actual temperature reaches or exceeds a predetermined value above the first temperature threshold, or generally as long as the defrost signal is present. Furthermore, in step M72, the fan 3 is operated for a predetermined period of time, or as long as the defrost signal is present. For example, the fan 3 can be operated at least as long as the supply of refrigerant to the evaporator 20 is interrupted. In the example of Fig. 5The supply of refrigerant to the evaporator 20 is interrupted until a fifth temperature threshold T5 is reached or exceeded, which lies at a temperature above the third temperature threshold T3. The fifth temperature threshold T5 is reached at time t52. At this time, signal S6 changes from "1" to "0." Thus, the defrost signal is removed and the supply of refrigerant to the evaporator 20 resumes, as can be seen from the change in signal S1 from "0" to "1" and from the actual temperature decreasing again from time t52. Since the actual temperature Ta in the storage room 10 at time t52 is above the third temperature threshold T3, the fan 3 continues to operate according to steps M1 to M5 of method M until the actual temperature reaches the fourth temperature threshold T4 at time t53.

[0060] Although the present invention has been explained above using exemplary embodiments, it is not limited thereto, but can be modified in a variety of ways. In particular, combinations of the above embodiments are also conceivable. REFERENCE SYMBOL

[0061] 1Inner container 1ABottom 1Bceiling 1CRear wall 1DSide walls 2Refrigerant circuit 3Fan 4Sensor system 5Control device 10Storage room 11Cooling compartment 12Cold storage compartment 13Intermediate floor 20Evaporator 21Compressor 22Condenser 41Temperature sensor 42Ambient temperature sensor 100Refrigeration appliance 110Carcass 112Insulating material 115Door AHatched area CTransverse direction dT1First temperature difference dT2Second temperature difference GDirection of gravity D0-D4Process steps MProcess M1-M7Process steps M 11, M12Process steps M71, M72Process steps S1, S2, S3Signals TDepth direction TaActual temperature T1First temperature threshold T2Second temperature threshold T3third temperature threshold T4fourth temperature threshold Vvertical direction

Claims

1. A method (M) for operating a refrigeration device (100), comprising: detecting (M1) an actual temperature in a storage space (10) of the refrigeration device (100), which storage space extends in a vertical direction (V) and has a refrigeration compartment (11) and a cold storage compartment (12) located below the refrigeration compartment (11) with respect to the vertical direction (V); supplying (M2) an evaporator (20) thermally coupled to the storage space (10) with refrigerant in order to extract heat from the storage space (10) when the actual temperature reaches or exceeds a first temperature threshold; interrupting (M5) the supply of refrigerant to the evaporator (20) when the actual temperature reaches or falls below a second temperature threshold that is lower than the first temperature threshold;Operating (M3) a fan (3) positioned in the refrigerated compartment (11) of the storage room (1) to generate air circulation within the storage room (1) when the actual temperature reaches or exceeds a third temperature threshold, which is greater than the first temperature threshold; and stopping (M4) the operation of the fan (3) when the actual temperature reaches or falls below a fourth temperature threshold, which is lower than the first temperature threshold and greater than or equal to the second temperature threshold, so that after stopping the fan (3), a temperature distribution in the storage room (10) is established due to natural convection, in which the actual temperature in the cold storage compartment (12) is lower than in the refrigerated compartment (11).

2. Method (M) according to claim 1, wherein the fourth temperature threshold is greater than the second temperature threshold.

3. The method (M) according to claim 1 or 2, additionally comprising: detecting (M11) an ambient temperature; and determining (M12) the third temperature threshold and / or the fourth temperature threshold depending on the ambient temperature.

4. Method (M) according to claim 3, wherein the third temperature threshold is determined as a function of the ambient temperature such that a first temperature difference between the first temperature threshold and the third temperature threshold decreases with increasing outside temperature.

5. Method (M) according to claim 3 or 4, wherein the fourth temperature threshold is determined as a function of the ambient temperature such that a second difference between the second temperature threshold and the fourth temperature threshold decreases with increasing outside temperature.

6. Method (M) according to one of the preceding claims, wherein a difference between the first temperature threshold value and the second temperature threshold value lies in a range between 0.25 and 3 Kelvin, in particular between 0.25 and 1.5 Kelvin.

7. Method (M) according to one of the preceding claims, wherein the third temperature threshold is up to 4 K higher than the first temperature threshold.

8. Method (M) according to one of the preceding claims, wherein the evaporator (20) is supplied with refrigerant by means of a compressor (21), and wherein operation (M3) of the fan (3) only takes place when the compressor (21) supplies the evaporator (21) with refrigerant.

9. Method (M) according to one of the preceding claims, additionally comprising: detecting (D0) a defrost signal; and performing (M7) a defrost process when the defrost signal is detected, regardless of the detected actual temperature, wherein the defrost process comprises: interrupting (M71) the supply of refrigerant to the evaporator (20); and operating (M72) the fan (3) for a predetermined period of time.

10. A refrigeration appliance (100), in particular a household refrigeration appliance, comprising: a storage space (10) extending in a vertical direction (V), which storage space has a refrigeration compartment (11) and a cold storage compartment (12) located below the refrigeration compartment (11) with respect to the vertical direction (V); a refrigerant circuit (2) with an evaporator (20) thermally coupled to the storage space (10) in order to extract heat from the storage space (10) by supplying the evaporator (20) with refrigerant; a fan (3) arranged in the refrigeration compartment (11), which fan is designed to generate air circulation within the storage space (10); a temperature sensor (4) connected to the storage space (10) and designed to detect an actual temperature in the storage space (10);and a control device (5) which is signal-connected to the temperature sensor (41), the refrigerant circuit (2) and the fan (3), which control device is designed to operate the refrigeration appliance (100) according to a method (M) according to one of the preceding claims.; 11. Refrigeration appliance (100) according to claim 10, wherein the storage space (10) is delimited with respect to the vertical direction (V) by a floor (1A) and a ceiling (1B) opposite thereto, and wherein the cold storage compartment (12) is positioned in an end region of the storage space (1) facing the floor (1A).

12. Refrigeration appliance (100) according to claim 10 or 11, wherein the storage space (10) is delimited by a rear wall (1C) with respect to a depth direction (T), and wherein the evaporator (20) is arranged on a side of the rear wall (1C) facing away from the storage space (10), wherein it is in heat-conducting contact with a wall (1A, 1B, 1C) delimiting the storage space (10).

13. Refrigeration device (100) according to one of claims 10 to 12, wherein the evaporator (20) is arranged without a fluidic connection to the storage space (10).

14. Refrigeration appliance (100) according to one of claims 10 to 13, wherein the cold storage compartment (12) is separated from the cooling compartment (11) with respect to the vertical direction (V) by an intermediate floor (13).

15. Refrigeration appliance (100) according to one of the preceding claims, wherein the temperature sensor (41) is connected to the cooling compartment (11) in order to detect a temperature in the cooling compartment (11) as the actual temperature of the storage space (10).

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