Refrigeration device and method for operating a refrigeration device

Abstract

A refrigeration appliance and a method for operating a refrigeration appliance are described. The refrigeration appliance has a refrigerator compartment and a freezer compartment, which are cooled by evaporators connected in parallel. The evaporators are supplied with refrigerant sequentially or in parallel. When both evaporators are supplied in parallel, a flow limiting circuit can be activated via a valve arrangement to restrict the flow of refrigerant into the evaporator cooling the freezer compartment and thereby ensure that both evaporators are sufficiently filled with refrigerant.

Description

TECHNICAL AREA

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

[0002] Household refrigerators can have multiple compartments designed for different temperature levels. For example, a household refrigerator might have a refrigerator compartment, typically operating in a temperature range of about 0°C to about +12°C, and a freezer compartment, typically operating in a temperature range of about -5°C to about -25°C. A refrigerant circuit is usually employed to extract heat from the compartments by evaporating refrigerant in an evaporator and releasing this heat to the environment by condensing the refrigerant in a condenser.

[0003] To operate the various storage compartments at different temperatures, refrigerant circuits with multiple evaporators can be used, with each storage compartment having its own evaporator, and the individual evaporators connected in parallel to a condenser. The outlets of the individual evaporators are typically connected to a suction line, which is connected to a compressor.

[0004] For efficiency reasons, it is advantageous to supply the evaporators with refrigerant alternately. In this sequential operation, refrigerant is typically circulated first exclusively through the evaporator cooling the colder storage compartment, and then exclusively through the other evaporator cooling the warmer storage compartment. A valve arrangement is usually provided to supply each evaporator individually with refrigerant. When only the evaporator for the warmer storage compartment is supplied with refrigerant, connecting multiple evaporators to the common suction line can cause refrigerant to flow back into the evaporator for the colder storage compartment. Therefore, a check valve is usually provided between the outlet of the evaporator for the colder storage compartment and the suction line.In such a configuration, the sequential operation in the individual evaporators makes it easy to achieve a vapor pressure suitable for the respective target temperature of the storage compartment, which improves the energy efficiency of the refrigerant circuit.

[0005] However, if there is a strong heat input into the storage compartments, sequential operation can lead to temporarily strong and possibly unacceptably high temperature increases, as the heat is only dissipated in intervals.

[0006] In addition to the sequential operation described above, the prior art also includes the simultaneous supply of parallel-connected evaporators in various configurations.

[0007] For example, JP 2011-012885 A describes a refrigerant circuit with a first evaporator coupled to a refrigerator compartment and a second evaporator coupled to a freezer compartment, whereby initially only the first evaporator is used to cool the refrigerator compartment, and immediately afterwards, via a valve, the flow is switched to a parallel supply to both evaporators and the flow to the first evaporator cooling the refrigerator compartment is reduced in order to lower the evaporation temperature there.

[0008] Another refrigerant circuit with parallel evaporators, which are simultaneously flowed through in a parallel operating mode, is disclosed in JP 2005-164070 A.

[0009] To achieve rapid cooling of several storage compartments, EP 3 447 407 A1 describes a refrigeration appliance with two separate refrigerant circuits for the refrigerator compartment and the freezer compartment. SUMMARY OF THE INVENTION

[0010] One of the objectives of the present invention is to provide improved solutions for cooling multiple storage compartments at different temperature levels, in particular solutions that enable energy-efficient operation and at the same time an effective response to high heat loads.

[0011] This problem is solved according to the invention by the subject matter of the independent claims. Advantageous embodiments and further developments result from the dependent claims referring back to the independent claims in conjunction with the description.

[0012] According to a first aspect of the invention, a refrigeration appliance, in particular a household refrigeration appliance, is provided. The refrigeration appliance comprises a refrigerator compartment, a freezer compartment, and a refrigerant circuit. The refrigerant circuit comprises a first evaporator thermally coupled to the refrigerator compartment, a first throttling device upstream of the first evaporator, a second evaporator thermally coupled to the freezer compartment, a second throttling device upstream of the second evaporator, a condenser, a compressor for circulating refrigerant through the evaporators and the condenser, and a valve arrangement. The first evaporator and the second evaporator are connected in parallel to an outlet of the condenser.The valve arrangement is switchable between a first switching state, in which it connects the outlet of the condenser only to one inlet of the first condenser; a second switching state, in which it connects the outlet of the condenser only to one inlet of the second condenser; and a third switching state, in which it connects the outlet of the condenser to both the inlet of the first condenser and the inlet of the second condenser. This means that when the compressor is operating, in the first switching state only the first evaporator is filled with refrigerant; in the second switching state only the second evaporator is filled; and in the third switching state both evaporators are filled in parallel or simultaneously.

[0013] The refrigerant circuit also features a flow limiting circuit, which, by means of the valve assembly, can be connected upstream of the second evaporator in its third switching state. This increases the flow resistance for the refrigerant flowing to the second evaporator in the third switching state compared to the second switching state. In other words, the valve assembly is designed to engage the flow limiting circuit in the refrigerant circuit when it is switched to its third switching state. In this third switching state, the flow limiting circuit increases the flow resistance in the flow path leading to the second evaporator compared to the flow path leading to the second evaporator in the second switching state. This limits the refrigerant flow to the second evaporator when flowing in parallel.

[0014] The refrigeration unit further comprises a sensor system designed to detect one or more quantities representing a heat input into the refrigerator compartment and one or more quantities representing a heat input into the freezer compartment, and a control system which is signal-connected to the compressor, the valve arrangement, and the sensor system.

[0015] The control system is set up for this purpose: - to determine the heat input into the refrigerator compartment and the freezer compartment based on the quantities recorded by the sensor system, - to operate the compressor and to alternately switch the valve arrangement between its first switching state and its second switching state, so that the first and second evaporators are sequentially supplied with refrigerant when the determined heat input is greater than a first limit value and less than a second limit value, and - to operate the compressor and switch the valve arrangement to its third switching state, so that the evaporators are supplied with refrigerant simultaneously when the determined heat input is greater than or equal to the second limit value.

[0016] According to a second aspect of the invention, a method for operating a refrigeration appliance, in particular a refrigeration appliance according to the first aspect of the invention, is provided. The method comprises detecting one or more physical quantities representing a heat input into a refrigerator compartment of the refrigeration appliance and one or more physical quantities representing a heat input into a freezer compartment of the refrigeration appliance; determining a heat input into the refrigerator compartment and the freezer compartment based on the detected quantity(s); circulating refrigerant alternately through a first evaporator thermally coupled to the refrigerator compartment and a second evaporator thermally coupled to the freezer compartment and connected in parallel to the first evaporator when the determined heat input is greater than a first limit value and less than a second limit value; and simultaneously circulating refrigerant through the first evaporator and the freezer compartment.parallel through the first evaporator and the second evaporator if the determined heat input is greater than or equal to the second limit value, wherein a flow limiting circuit is placed upstream of the second evaporator to increase a flow resistance for the refrigerant flowing to the second evaporator.

[0017] According to the invention, the parallel-connected evaporators for cooling the refrigerator and freezer compartments are supplied sequentially when the heat input to the refrigerator and / or freezer compartment is low or normal. This means that the valve arrangement is switched such that the first and second evaporators are supplied alternately. The heat loads of the compartments are determined based on limit values. If the heat input in at least one of the compartments exceeds a first limit value that is lower than a second limit value, the sequential supply is initiated, preferably supplying first the evaporator that is thermally coupled to the compartment in which the heat input exceeds the first limit value.

[0018] However, if the heat input into at least one of the compartments exceeds the second limit value—for example, if the first limit value is exceeded in one compartment and the other compartment still requires cooling—the valve assembly switches to its third state, so that both evaporators are supplied with refrigerant simultaneously or in parallel. The second limit value for heat input is higher than the first. Physical quantities representing the heat input can include, for example, the current temperature in the storage compartment and the freezer compartment, and / or the opening time of a door closing the refrigerator compartment and a door closing the freezer compartment.

[0019] Since the temperature in the refrigerator compartment is higher than in the freezer compartment, the evaporation pressure in the first evaporator is higher than in the second. The greater the temperature difference between the compartments, the more pronounced this effect. Particularly under high heat loads in the refrigerator compartment, significant differences can therefore occur between the evaporation pressure in the first evaporator and the evaporation pressure in the second evaporator. The flow limiting circuit, activated in the third switching state of the valve assembly, prevents excessive refrigerant flow into the second evaporator, which cools the freezer compartment, and, more importantly, ensures a sufficient flow of refrigerant into the first evaporator, which cools the refrigerator compartment, even with significant differences in evaporation pressures.This ensures that the refrigerant distribution is adapted to the cooling requirements of both compartments when both evaporators are supplied in parallel, and both compartments can be effectively cooled back to the desired target temperature.

[0020] Switching between sequential and parallel power supply allows for flexible adaptation to device usage. Parallel power supply provides better temperature stability and faster cooling, while the more efficient sequential power supply mode can be used when usage is lower.

[0021] According to some embodiments, the valve arrangement may include a rotary valve with an inlet connected to the outlet of the condenser, a first outlet connected to the inlet of the first evaporator, and a second outlet connected to the inlet of the second evaporator.

[0022] According to some embodiments, the second throttling device may have a first throttle and a second throttle connected in parallel to it, which is part of the flow-limiting circuit and has a higher flow resistance than the first throttle. The valve arrangement connects the outlet of the condenser to the inlet of the second condenser via the first throttle in its second switching state and via the second throttle in its third switching state. Thus, the second evaporator, which cools the freezer compartment, can have two throttles connected in parallel upstream, a first throttle having a higher flow resistance and a second throttle having a higher flow resistance. When both evaporators are supplied in parallel, the valve arrangement is switched so that flow is only through the second throttle with the higher flow resistance.This ensures that the refrigerant flow is distributed as desired between the first and second evaporators, since the second restrictor limits the flow into the second evaporator. A further advantage is that the second restrictor can reduce the refrigerant pressure, thereby further lowering the evaporation temperature in the second evaporator. This promotes rapid and effective cooling of the freezer compartment, especially when there is a high heat input.

[0023] According to some embodiments, the first throttle may be designed as the first capillary tube, and / or the second throttle may be designed as the second capillary tube.

[0024] If the valve arrangement includes the rotary valve described above, some embodiments may provide that the second output of the rotary valve is connected to the first throttle of the second throttle device, and that the rotary valve has a third output connected to the second throttle of the second throttle device. This allows switching between the two throttles of the second throttle device using a single rotary valve. In combination with the parallel throttles, this creates a robust and easily switchable implementation of the flow limiting circuit.

[0025] According to some embodiments, the valve arrangement may include an integrated flow restrictor as part of the flow limiting circuit. This flow restrictor is switchable between a first flow state, in which it represents a first flow resistance, and a second flow state, in which it represents a second flow resistance greater than the first. The flow restrictor is integrated into the valve arrangement such that, in the second switching state of the valve arrangement (and optionally also in its first switching state), it assumes the first flow state, and in the third switching state of the valve arrangement, it assumes the second flow state. That is, if the valve arrangement is configured to supply both evaporators in parallel, a flow restrictor can be connected to an output of the valve arrangement supplying the second evaporator.This achieves a simple limitation of the refrigerant flow into the second evaporator, integrated into the valve arrangement.

[0026] If the valve arrangement includes the rotary valve described above, some embodiments provide for the flow restrictor to be formed by a perforated disk integrated into the rotary valve. This disk has a first hole with a first diameter, which is located in the second outlet in the second switching state, and a second hole with a second diameter, which is located in the second outlet in the third switching state, the second diameter being smaller than the first. The second hole with the smaller diameter can thus be advanced towards the second outlet in the third switching state of the valve arrangement, similar to an orifice plate, to reduce its effective flow diameter. This creates a robust and easily switchable implementation of the flow restrictor.

[0027] According to some embodiments, the first throttling device may have a first throttle and a second throttle connected in parallel to it, which has a lower flow resistance than the first throttle. The valve arrangement connects the condenser outlet to the inlet of the first condenser via the first throttle in its first switching state and via the second throttle in its third switching state. Thus, in addition to restricting the flow of refrigerant to the second evaporator, a flow of refrigerant to the first evaporator can be promoted by allowing the flow to pass through a second throttle with lower flow resistance in the third switching state of the valve arrangement. This allows for a more reliable filling of the first evaporator, which promotes rapid cooling, especially under high heat loads in the refrigerator compartment.

[0028] According to some embodiments, it may be provided that the first throttle of the first throttle device is designed as the first capillary tube, and / or the second throttle of the first throttle device is designed as the second capillary tube.

[0029] If the valve arrangement includes a rotary valve, as described above, the first output of the rotary valve can be connected to the first throttle, and the rotary valve can have a third output connected to the second throttle. Optionally, the second throttle of the first throttle device and the second throttle of the second throttle device can be connected to the same output. This further simplifies switching to parallel operation despite the additional throttles.

[0030] According to some embodiments, the refrigerant circuit may further include a check valve arranged between an outlet of the second compressor and a suction line connecting the first and second evaporators to a suction port of the compressor. The check valve is positioned between an outlet of the second compressor and the suction line in such a way as to prevent refrigerant from flowing back from the suction line into the second evaporator. This is particularly advantageous when the evaporators are supplied sequentially, when the valve arrangement is in its first switching state and thus only the first evaporator is being supplied, as it prevents refrigerant from accumulating in the second evaporator due to the higher evaporation pressure in the first evaporator.

[0031] According to some embodiments, the refrigerant circuit may further include a shut-off valve located between the condenser outlet and the valve assembly. The control system is connected to the shut-off valve via a signal conductor and is configured to close the shut-off valve for a predetermined period during the sequential supply of the evaporators before the valve assembly switches from the second to the first switching state, in order to extract refrigerant from the second evaporator. Thus, a so-called transfer pumping operation can take place before each supply to the first evaporator, whereby refrigerant is extracted from the second evaporator and pumped to the warm side of the refrigerant circuit, in particular to the area between the compressor and the shut-off valve, with the refrigerant primarily accumulating in the condenser.This allows for a beneficial increase in the amount of refrigerant available to supply the first evaporator. Optionally, a transfer of refrigerant can also take place after the parallel supply, whereby the shut-off valve is closed and the compressor continues to operate before the valve unit is switched to its first switching state.

[0032] According to some embodiments, the sensor system may include a first temperature sensor designed to detect a first actual temperature in the refrigerator compartment and a second temperature sensor designed to detect a second actual temperature in the freezer compartment.

[0033] According to some embodiments, the first limit value may be exceeded, for example, when a first temperature difference between the first measured actual temperature and a first setpoint temperature for the refrigerator compartment exceeds a first differential limit value, or when a second temperature difference between the second measured actual temperature and a second setpoint temperature for the freezer compartment exceeds a second differential limit value. The first and second differential limits can be the same or different and depend on the setpoint temperature. Optionally, the first and second differential limits can be, for example, in a range of 1°C to 3°C. Thus, if the actual temperature in the respective compartment is more than 1°C to 3°C above the respective setpoint temperature, the sequential supply of the compartments can be initiated.

[0034] The second limit value can be exceeded, for example, if the first temperature difference exceeds a third limit value that is greater than the first, and / or if the second temperature difference exceeds a fourth limit value that is greater than the second. The third and fourth limits can be the same or different and depend on the respective target temperature. Optionally, the third and fourth limits can be, for example, in a range of 4°C to 6°C. If the actual temperature in one of the compartments deviates by more than the respective third or fourth temperature limit value, for example, by more than 4°C to 6°C above the respective target temperature, and the temperature difference between the actual and target temperatures in the other compartment is at least above the respective first or second temperature difference, the compartments can be supplied in parallel.

[0035] Optionally, the control system can be configured to switch the valve arrangement to the third switching state only if the third differential limit is exceeded for longer than a predetermined first period and / or if the fourth differential limit is exceeded for longer than a predetermined second period. Short-term heat peaks therefore do not necessarily trigger the activation of the parallel supply, which advantageously reduces energy consumption.

[0036] According to some embodiments, the compressor may be designed to operate at different speeds, with the control system configured to operate the compressor at a higher speed for parallel supply of the evaporators than for sequential supply. Since a higher cooling capacity is required for parallel supply of both evaporators, increasing the compressor speed is advantageous to further accelerate heat dissipation from the compartments.

[0037] According to some embodiments, the refrigeration unit may include a first compartment fan designed to circulate air between the first evaporator and the refrigeration compartment. The control system is connected to the first compartment fan via a signal and is configured to operate the first compartment fan at a lower speed during parallel refrigerant supply to the evaporators than during sequential supply. Thus, during parallel supply to the evaporators, i.e., when the valve arrangement is in its third switching state, the heat transfer at the first evaporator is reduced. This results in the first evaporator being filled with refrigerant to a greater degree.

[0038] According to some embodiments, the refrigeration unit may be provided with a second compartment fan designed to circulate air between the second evaporator and the freezer compartment. The control system is connected to the second compartment fan via a signal and is configured to operate the second compartment fan at a lower speed during parallel refrigerant supply to the evaporators than during sequential supply. Thus, during parallel supply to the evaporators, i.e., when the valve arrangement is in its third switching state, the heat transfer at the second evaporator is reduced. This results in the second evaporator being filled with a higher degree of refrigerant.

[0039] In some embodiments, the refrigeration unit may be provided with an external fan designed to transport an ambient airflow over the condenser. The control system is signal-connected to the external fan and is configured to operate the second external fan at a lower speed during parallel supply to the evaporators than during sequential supply. In this way, during parallel supply to the evaporators, i.e., when the valve arrangement is in its third switching state, the heat transfer at the condenser is reduced. This also lowers the refrigerant level in the condenser, allowing more refrigerant to be supplied to the evaporators, thus achieving a higher evaporator charge.

[0040] 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

[0041] The invention will now be explained with reference to the figures in the drawings. The figures show: Fig. 1 a simplified, schematic block representation of a refrigeration device according to an embodiment of the invention; Fig. 2 a simplified, schematic block representation of a refrigeration device according to an embodiment of the invention; and Fig. 3 a flowchart of a method for operating a refrigeration device according to an embodiment of the invention.

[0042] In the figures, the same reference symbols denote identical or functionally equivalent components, unless otherwise stated. DETAILED DESCRIPTION OF EXAMPLES OF EXECUTION

[0043] Fig. Figure 1 shows an example of a refrigeration appliance 100 in the form of a refrigerator-freezer combination. However, the invention is not limited to this, but can generally be used in refrigeration appliances, in particular in refrigeration appliances with multiple storage compartments, which are cooled by evaporators connected in parallel and are designed for operation at different temperatures.

[0044] As in Fig. As shown schematically in Figure 1, the refrigeration unit 100 comprises a cooling compartment 1, a freezer compartment 2, a refrigerant circuit 3, a sensor system 8 and a control system 9.

[0045] The cooling compartment 1 is designed to hold chilled goods such as food, beverages, medicines or the like and can be designed in particular for operation at a first target temperature in a range between 1°C and 8°C.

[0046] Freezer compartment 2 is used for storing frozen goods such as food, samples, or the like, and can be designed for operation at a second set temperature within a range of -14°C to -24°C. As shown in Fig. As shown schematically in Figure 1, the freezer compartment 2 can be spatially or physically separated from the refrigerator compartment 1.

[0047] Refrigerant circuit 3 shows, as in Fig. Figure 1 shows a first evaporator 31, a second evaporator 32, a compressor 33, and a condenser 34. Furthermore, the refrigerant circuit 3 comprises a first throttling device 4, a second throttling device 5, a valve assembly 6, and a flow limiting circuit DB. Optionally, a check valve 35 can also be integrated into the refrigerant circuit 3. Likewise, a shut-off valve 37 can be provided as an option.

[0048] The first evaporator 31 is thermally coupled to the refrigerator compartment 1 to extract heat from it by evaporating refrigerant. Optionally, the first evaporator 31 can be arranged in a first evaporator chamber (not shown) that is fluidically coupled to the refrigerator compartment 1, and an optional first compartment fan 11 can be provided, which is designed to circulate air between the first evaporator 31 or the first evaporator chamber and the refrigerator compartment 1. Alternatively, the first evaporator 31 can be thermally coupled to a wall that delimits the refrigerator compartment 1.

[0049] The second evaporator 32 is thermally coupled to the freezer compartment 2 to extract heat from it by evaporating refrigerant. Optionally, the second evaporator 32 can be arranged in a second evaporator chamber (not shown) that is fluidically coupled to the freezer compartment 2. An optional second compartment fan 12 can be provided, which is designed to circulate air between the second evaporator 32 or the second evaporator chamber and the freezer compartment 2. Alternatively, the second evaporator 32 can be thermally coupled to a wall bounding the freezer compartment 2 or arranged within the freezer compartment 2.

[0050] The compressor 33 has a suction port 33A, which is connected via a suction line 38 to an outlet 31B of the first evaporator 31 and an outlet 32B of the second evaporator 32, and a pressure port 33B, which is connected to an inlet 34A of the condenser 34. The compressor 33 is designed to circulate refrigerant through the refrigerant circuit 3, in particular through the condenser 34 and the evaporators 31 and 32. The compressor 33 draws gaseous refrigerant from the evaporators 31 and 32 via the suction line 38, compresses it, and supplies it to the condenser 34 via its pressure port 33B.

[0051] The condenser 34 is thermally coupled to the environment in order to condense the gaseous refrigerant coming from the compressor 33, releasing heat to the environment. As in Fig. Figure 1 is shown purely as an example; an external fan 13 can optionally be provided, which is designed to transport an ambient airflow over the condenser 34. This allows for a compact design of the condenser 34.

[0052] As in Fig. As shown schematically in Figure 1, an input 31A of the first evaporator 31 and an input 32A of the second evaporator 32 are connected in parallel with an output 34B of the condenser 34.

[0053] As in Fig. As further shown in Figure 1, the valve arrangement 6, which is described in detail below, is arranged between the outlet 34A of the condenser 34 and the inlet 31A of the first evaporator 31, as well as the inlet 32A of the second evaporator 32. The optional shut-off valve 37 can, for example, be arranged between the outlet 34A of the condenser 34 and the valve arrangement 6. The optional check valve 35 can be arranged as shown in Fig. 1 shown, located between the outlet 32B of the second evaporator 32 and the suction line 38.

[0054] The first throttling device 4 is connected upstream of the first evaporator 31 and can in particular be arranged between the valve arrangement 6 and the inlet 31A of the first evaporator 31, as shown in Fig. 1 shown. As in Fig. As further shown in Figure 1, the first throttling device 4 can have a first throttle 41, e.g. in the form of a capillary tube. The first throttling device 4, here the first throttle 41, is particularly designed to expand refrigerant coming from condenser 34 before it is fed to the first evaporator 31.

[0055] The second throttling device 5 is connected upstream of the second evaporator 32 and can in particular be arranged between the valve arrangement 6 and the inlet 32A of the second evaporator 32, as shown in Fig. 1 shown. As in Fig. As further shown in Figure 1, the second throttling device 5 can have a first throttle 51, e.g., in the form of a capillary tube. The second throttling device 5, here the first throttle 51, is specifically designed to expand refrigerant coming from the condenser 34 before it is fed to the second evaporator 32. The first throttle 51 of the second throttling device 5 can, for example, have a greater flow resistance than the first throttle 41 of the first throttling device 4.

[0056] The valve assembly 6 is switchable between a first switching state, a second switching state, and a third switching state. In the first switching state, the valve assembly 6 connects the output 34B of the condenser 34 only to the input 31A of the first evaporator 31. When the compressor 33 is operating, in the first switching state of the valve assembly 6, only the first evaporator 31 is supplied with refrigerant. In the second switching state, the valve assembly 6 connects the output 34B of the condenser 34 only to the input 32A of the second evaporator 32. When the compressor 33 is operating, in the second switching state of the valve assembly 6, only the second evaporator 32 is supplied with refrigerant. In the third switching state, which is described in Fig. As shown schematically in Figure 1, the valve arrangement 6 connects the outlet 34B of the condenser 34 to both the inlet 31A of the first condenser 31 and the inlet 32A of the second condenser 32. When the compressor 33 is operated, in the third switching state of the valve arrangement 6 both the first evaporator 31 and the second evaporator 32 are supplied with refrigerant simultaneously.

[0057] To implement these functions, the valve arrangement 6 can, for example, include a rotary valve 60, as shown in Fig. Figure 1 is shown schematically and by way of example. The rotary valve 60 can, for example, have an inlet 61 connected to the outlet 34A of the condenser 34, a first outlet 62 connected to the inlet 31A of the first evaporator 31, and a second outlet 63 connected to the inlet 32A of the second evaporator 32. The inlet 61 can be optionally connected to the first outlet 62 (first switching state), the second outlet 63 (second switching state), or both the first and second outlets 63 (third switching state).

[0058] The flow limiting circuit DB serves to limit the flow of refrigerant into the second evaporator 32 in the third switching state in order to ensure that both evaporators 31, 32 are adequately filled with refrigerant.

[0059] Due to the higher temperatures in the refrigerator compartment 1 compared to the freezer compartment 2, the first evaporator 31 operates at a higher evaporation pressure than the second evaporator 32. Therefore, when only the first evaporator 31 is supplied with refrigerant in the first switching state of the valve arrangement 6, there is a tendency for refrigerant to flow from the suction line 38 into the second evaporator 32. However, this can be prevented by using the optional check valve 35. Furthermore, due to the higher evaporation pressure in the first evaporator 31, there is a tendency that when both evaporators 31 and 32 are supplied in parallel in the third switching state, the first evaporator 31 will receive too little refrigerant, while the second evaporator 32 will reach a high charge level.The flow limiting circuit DB counteracts this phenomenon and helps to achieve sufficient filling of both evaporators 31, 32 with refrigerant by increasing the flow resistance for the inflow of refrigerant into the second evaporator 32 in the third switching state of the valve arrangement 6 compared to the second switching state of the valve arrangement 6.

[0060] As in Fig. Figure 1, shown purely as an example and only schematically, illustrates that the flow limiting circuit DB can include a flow limiter 7 integrated into the valve arrangement 6. The flow limiter 7 can, for example, be switchable between a first flow state, in which it represents a first flow resistance, and a second flow state, in which it represents a second flow resistance that is greater than the first flow resistance. To limit the inflow of refrigerant into the second evaporator 32 in the third switching state of the valve arrangement 6, the flow limiter 7 can, in particular, be integrated into the valve arrangement 6 such that it assumes the first flow state in the second switching state of the valve arrangement 6 and the second flow state in the third switching state of the valve arrangement 6.

[0061] As in Fig. Figure 1, shown purely schematically, shows that the flow restrictor 7 can, for example, be formed by a perforated disc 65 integrated into the rotary valve 60. This disc can have a first hole with a first diameter, which in the second switching state is located in the second outlet 63, and a second hole with a second diameter, which in the third switching state is located in the second outlet 63, wherein the second diameter is smaller than the first diameter. Fig. In the second outlet 63, the perforated disk 65 is arranged with the smaller second hole. The smaller hole thus results in a smaller flow diameter than the first hole and therefore limits the flow of refrigerant to the second evaporator.

[0062] The sensor system 8 can, for example, include a first temperature sensor 81 for detecting an initial actual temperature in the refrigerator compartment 1. As in Fig. Figure 1 shows a schematic and purely exemplary representation of the first temperature sensor 81, which can be located, for example, in the refrigerator compartment 1. Furthermore, a first door opening sensor (not shown) can optionally be provided, which can detect the open state of a door (not shown) closing the refrigerator compartment 1.

[0063] As in Fig. As further shown by way of example in Figure 1, the sensor system 8 can have a second temperature sensor 82 for detecting a second actual temperature in the freezer compartment 2. As shown in Figure 1 Fig. In the schematic and purely exemplary representation, the second temperature sensor 82 can, for example, be located in freezer compartment 2. Furthermore, a second door opening sensor (not shown) can optionally be provided, which can detect the open / closed state of a door (not shown) closing freezer compartment 2. A deviation of the actual temperature from a setpoint temperature for the respective compartment 1, 2 is representative of a heat input into, or a heat load in, the respective compartment 1, 2. If the door of the respective compartment 1, 2 is open, warm ambient air can enter the respective compartment 1, 2, thus causing a heat input into the respective compartment 1, 2. In general, the sensor system 8 is therefore designed to detect one or more quantities representing a heat input into the refrigerator compartment 1 and one or more quantities representing a heat input into the freezer compartment 2.

[0064] Control 9 is in Fig. 1 is also only schematically represented as a block and can, for example, be implemented as an electronic control unit. In particular, the controller 9 can have a processor, e.g., in the form of a CPU, an FPGA, an ASIC, or the like, and a data storage device, e.g., in the form of a non-volatile data storage medium such as flash memory, SD memory, or the like. The data storage device is readable by the processor and can store executable software. For example, the software can contain program instructions that cause the processor to generate output signals, such as control signals, based on external input signals, such as measurement signals.

[0065] The control unit 9 is connected to the compressor 33, the sensor system 8, and the valve assembly 6 via a signal connection. If provided, the control unit 9 can also be connected to one or more of the following components via a signal connection: the first compartment fan 11, the second compartment fan 12, the external fan 13, and the shut-off valve 37. The signal connection can be wired, e.g., via a bus system, or wireless, e.g., WiFi, NFC, Bluetooth, or similar.

[0066] In general, the controller 9 can be configured to output a control signal to the compressor 33 to activate and deactivate it and, optionally, to vary its speed. Similarly, the controller 9 can be configured to output a switching signal to the valve assembly 6 to switch it between its first, second, and third switching states. Furthermore, the controller 9 can be configured to output a control signal to the first compartment fan 11 to activate and deactivate it and, optionally, to vary its speed. Optionally, the controller 9 can also be configured to output a control signal to the second compartment fan 12 to activate and deactivate it and, optionally, to vary its speed.Optionally, the controller 9 can also be configured to output a control signal to the external fan 13 to activate and deactivate it and, optionally, to vary its speed. Furthermore, optionally, the controller 9 can be configured to output a switching signal to the shut-off valve 37 to switch it between its open and closed states.

[0067] The control unit 9 can be configured to operate the refrigeration unit 100 according to a predetermined procedure, as will be explained in detail below.

[0068] Fig. Figure 2 shows another refrigeration unit 100, which differs from the one in Fig. The refrigeration unit 100 shown in 1 differs only in the implementation of the flow limiting circuit DB.

[0069] As in Fig. As shown in Figure 2 as an example, alternatively or additionally to the flow limiter 7 integrated into the valve arrangement 6, the second throttle device 5 upstream of the second evaporator 32 can have a second throttle 52, which is connected in parallel to the first throttle 51 and has a higher flow resistance than the first throttle 51 of the second throttle device 5. The second throttle 52 thus forms part of the flow limiting circuit DB. The second throttle 52 can, for example, be designed as a second capillary tube, as shown in Figure 2. Fig. 2. Illustrated by way of example and schematically.

[0070] As in Fig. As shown schematically in Figure 2, the rotary valve 60 can, for example, have a third output 63 in addition to the second output 63, wherein the second output 63 of the rotary valve 60 is connected to the first throttle 51, and the third output 64 is connected to the second throttle 52. Thus, in the second switching state of the valve arrangement 6, the second output 63 of the rotary valve 60 is connected via the first throttle 51 to the input 32A of the second evaporator 32, and in the third switching state of the valve arrangement 6, the third output 64 of the rotary valve 60 is connected via the second throttle 52 to the input 32A of the second evaporator 32, as shown in Figure 2. Fig. Figure 2 is shown schematically. In general, the valve arrangement 6 can be connected to the first and second throttles 51, 52 of the second throttle device 5 such that, in its second switching state, the valve arrangement 6 connects the outlet 34B of the condenser 34 to the inlet 32A of the second evaporator 32 via the first throttle 51, and in its third switching state via the second throttle 52. Thus, in the third switching state of the valve arrangement 6, refrigerant can be directed to the second evaporator 32 via the second throttle 52, which has a high flow resistance compared to the first throttle 51. This limits the flow of refrigerant into the second evaporator 32.

[0071] As in Fig. 2. Furthermore, as shown purely by way of example, the first throttle device 4 can optionally also have a second throttle 42, which is connected in parallel to the first throttle 41 of the first throttle device 4. However, the second throttle 42 of the first throttle device 4 has a lower flow resistance than the first throttle 41 of the first throttle device 4. As shown in Fig. Figure 2 is purely exemplary and only schematically represented; the second throttle 42 of the first throttle device 4 can be designed as a capillary tube.

[0072] As in Fig. Figure 2, shown purely as an example, shows that the second throttle 42 of the first throttle device 4 can optionally also be connected to the third outlet 64 of the rotary valve 60, so that in the third switching state of the valve arrangement 6, the inlet 31A of the first evaporator 31 is connected to the third outlet 64 of the rotary valve 60 via the second throttle 42. Alternatively, an additional fourth outlet (not shown) can also be provided on the rotary valve 60, to which the second throttle 42 of the first throttle device 4 is connected. In general, the valve arrangement 6 can be connected to the first and second throttles 41, 42 of the first throttle device 4 such that the valve arrangement 6 connects the outlet 34B of the condenser 34 to the inlet 31A of the first condenser 31 via the first throttle 41 in its first switching state and via the second throttle 42 in its third switching state.

[0073] Thus, in the third switching state of the valve arrangement 6, a flow path between the condenser 34 and the first evaporator 31 can be realized, which has a lower flow resistance than a flow path that connects the condenser 34 and the first evaporator 31 in the first switching state of the valve arrangement 6, and additionally, in the third switching state of the valve arrangement 6, a flow path between the condenser 34 and the second evaporator 32 is realized, which has a higher flow resistance than a flow path that connects the condenser 34 and the second evaporator 32 in the second switching state of the valve arrangement 6.Furthermore, the flow resistance for the refrigerant from the condenser 34 to the first evaporator 31 is reduced in relation to the flow resistance for the refrigerant from the condenser 34 to the second evaporator 32, thereby achieving a more uniform distribution of the refrigerant to both evaporators 31, 32 even at high vapor pressures in the first evaporator 31.

[0074] Fig. Figure 3 schematically shows the sequence of a procedure M for operating a refrigeration unit 100. The control unit 9 can, for example, be configured to cause the refrigeration units 100 described above to execute the procedure M or to operate the refrigeration units 100 according to the procedure M. The in Fig. The 3 methods M shown will therefore be referred to below with reference to the methods described in the Fig. 1 and Fig. The two refrigeration units shown are described in detail.

[0075] In step M1, one or more physical quantities representing heat input into refrigerator compartment 1 and one or more physical quantities representing heat input into freezer compartment 2 are detected by means of the sensor system 8. For example, the first temperature sensor 81 can detect the first current temperature in refrigerator compartment 1, and the second temperature sensor 82 can detect the second current temperature in freezer compartment 2. Optionally, the door sensors, if provided, can detect when the refrigerator compartment door and / or the freezer compartment door is opened.

[0076] In step M2, the controller 9 determines the heat input into refrigerator compartment 1 and freezer compartment 2 based on the parameters detected by the sensor system 8. For example, the controller 9 can calculate a first temperature difference between the first actual temperature and a first setpoint temperature for refrigerator compartment 1, and a second temperature difference between the second actual temperature and a second setpoint temperature for freezer compartment 2. Optionally, the controller 9 can also determine the first door opening period of the refrigerator and freezer compartment doors based on the measurement signals output by the door sensors, if any are installed.

[0077] In a first verification step M21, the controller 9 determines whether the measured heat input exceeds a first limit value. For this purpose, the controller 9 can, for example, compare the first temperature difference between the first actual temperature and the first setpoint temperature for refrigerator compartment 1 with a first differential limit value, and the second temperature difference between the second actual temperature and the second setpoint temperature for freezer compartment 2 with a second differential limit value. If at least one of the temperature differences—the first temperature difference—exceeds the first differential limit value and / or the second temperature difference—exceeds the second differential limit value, the controller 9 determines that the first limit value has been exceeded.

[0078] If neither the first nor the second temperature difference reaches the respective difference limit, as is the case in Fig. 3, indicated by the symbol “-”, procedure M returns to step M1. If the first limit, as explained above and in Fig. 3, indicated by the symbol “+”, the procedure proceeds to a second verification step M22.

[0079] In the second verification step M22, the controller 9 determines whether the measured heat input exceeds a second limit value. For this purpose, the controller 9 can, for example, compare the first temperature difference between the first actual temperature and the first setpoint temperature for refrigerator compartment 1 with a third differential limit value that is greater than the first differential limit value. The third differential limit value thus defines a larger difference between the first actual temperature and the first setpoint temperature than the first differential limit value. Additionally, the controller 9 can compare the second temperature difference between the second actual temperature in freezer compartment 2 and the second setpoint temperature in freezer compartment 2 with a fourth differential limit value that is greater than the second temperature limit value.The fourth differential limit thus defines a larger difference between the second actual temperature and the second setpoint temperature than the second differential limit. If the controller 9 determines that the first temperature difference exceeds the third differential limit and / or that the second temperature difference exceeds the fourth differential limit, as in... Fig. 3, represented by the symbol “+”, the procedure M proceeds to step M4. However, if neither the first temperature difference exceeds the third difference limit nor the second temperature difference exceeds the fourth difference limit, the second limit is not exceeded, as shown in Fig. 3 is represented by the symbol “-”. In this case, procedure M proceeds to step M3.

[0080] In step M3, the controller 9 alternately switches the valve assembly 6 between its first and second switching states and activates the compressor 33 to circulate refrigerant sequentially through the first evaporator 31 and the second evaporator 32. For example, for an initial supply period, the first switching state of the valve assembly 6 can be activated to supply the first evaporator 31 with refrigerant and cool the refrigerator compartment 1. In this case, the second evaporator 32 is not supplied with refrigerant. If necessary, the optional check valve 35 helps to prevent refrigerant from flowing from the suction line 38 into the second evaporator 32. After the first supply period, the controller 9 can switch the valve assembly 6 to the second switching state for a second supply period, so that only the second evaporator 32 is supplied with refrigerant.This is referred to as sequential operation or sequential supply of the evaporators 31, 32. One advantage of this operating mode is that energy-efficient operation of the refrigerant circuit 3 is possible.

[0081] Optionally, the controller 9 in step M3 can be configured to close the shut-off valve 37 for a predetermined period before the valve arrangement 6 switches from the second to the first switching state, during which time the compressor 33 continues to operate to extract refrigerant from the second evaporator 32. For example, after the second supply period has ended and before the first supply period begins again, an intermediate period can be provided in which the shut-off valve 37 is closed while the compressor 33 is running. This is referred to as recirculation and helps to transfer refrigerant from the second evaporator 32 to the warm side of the refrigerant circuit 3, so that it is available for the subsequent supply of the first evaporator 31.

[0082] During the execution of step M3, the control unit 9, particularly while the valve arrangement 6 is in its first switching position, can control the first compartment fan 11 to operate it at a predetermined first speed, so that it circulates air between the first evaporator 31 and the cooling compartment 1.

[0083] Similarly, during the execution of step M3, the control unit 9, particularly while the valve arrangement 6 is in its second switching position, can control the second compartment fan 12 to operate it at a predetermined second speed, so that it circulates air between the second evaporator 32 and the freezer compartment 2.

[0084] Optionally, during the execution of step M3, the controller 9 can control the external fan 13 to operate it at a predetermined third speed, so that it supplies the condenser 34 with an ambient airflow.

[0085] In step M4, which is executed when the determined heat input exceeds the second limit value, as explained above, the controller 9 switches the valve arrangement 6 to its third switching state and activates the compressor 33 to circulate refrigerant simultaneously through both the first evaporator 31 and the second evaporator 32. This is also referred to below as parallel operation or parallel supply of the evaporators 31 and 32. Optionally, the controller 9 can operate the compressor 33 at a higher speed for parallel supply of the evaporators 31 and 32 in step M4 than for sequential supply of the evaporators 31 and 32 in step M3, in order to generate a higher refrigerant mass flow rate.

[0086] As from the Fig. 1 and Fig. As is clearly shown in Figure 2 and explained above, in step M4 the refrigerant is fed to the second evaporator 32 through the flow limiting circuit DB. This prevents a disproportionately large proportion of the refrigerant delivered by the compressor 33 from being supplied to the second evaporator 32, even at high evaporation pressures in the first evaporator 31. Instead, sufficient refrigerant charge can be achieved in both evaporators 31 and 32, resulting in high cooling capacity in both compartments 1 and 2.

[0087] At the in Fig. In the refrigerant circuit 3 shown in Figure 1, the refrigerant flows in step M4 through the first throttle 41 of the first throttle device 4 to the first evaporator 31, and through the flow restrictor 7 located in the third outlet 63 of the valve arrangement 6 in the third switching state and the first throttle 51 of the second throttle device 5 to the second evaporator 32. The flow restrictor 7 thus increases the flow resistance for the inflow of refrigerant into the second evaporator 32 and thereby helps to achieve sufficient filling of the first evaporator 31.

[0088] Similarly, in the case of the Fig.In the refrigerant circuit 3 shown in Figure 2, the refrigerant flows in step M4 through the optional second throttle 42 of the first throttle device 4 to the first evaporator 31, and through the second throttle 52 of the second throttle device 5 to the second evaporator 32. Since the second throttle 52 of the second throttle device 5 has a greater flow resistance than the first throttle 51 of the second throttle device 5, the flow resistance for the refrigerant flow into the second evaporator 32 is also increased in the third switching state of the valve arrangement 6. Furthermore, the optional second throttle 42 reduces the flow resistance for the refrigerant flow into the first evaporator 31.

[0089] In step M4, the controller 9 can optionally also control the first compartment fan 11 to operate it at a fourth speed, which is lower than the first speed of the first compartment fan 11. This means that the speed of the first compartment fan 11 can be reduced during the parallel supply of the evaporators 31, 32 in step M4 compared to the sequential supply in step M3. This reduces the heat transfer at the first evaporator 31 and thus further promotes the filling of the first evaporator 31 with refrigerant.

[0090] Similarly, in step M4, the controller 9 can control the second compartment fan 12 to operate it at a fifth speed, which is lower than the second speed of the second compartment fan 12. That is, the speed of the second compartment fan 12 can be reduced during the parallel supply of the evaporators 31 and 32 in step M4 compared to the sequential supply in step M3. This reduces the heat transfer at the second evaporator 32 and thus further promotes the filling of the second evaporator 32 with refrigerant.

[0091] If necessary, the controller in step M4 can also control the optional external fan 13 to operate it at a sixth speed, which is lower than the third speed of the external fan 13. This means that the speed of the external fan 13 can be reduced during the parallel supply of the evaporators 31, 32 in step M4 compared to the sequential supply in step M3. This reduces the heat transfer at the condenser 34. As a result, less refrigerant accumulates in the condenser 34. Consequently, more refrigerant is available to supply to the first and second evaporators 31, 32, thus further promoting the filling of the evaporators 31, 32 with refrigerant.

[0092] In step M4, the flow of refrigerant into the second evaporator 32 is generally limited relative to the first evaporator 31 due to the flow limiting circuit DB. Thus, when both evaporators 31 and 32 are supplied in parallel, a desired distribution of the refrigerant flow between the first and second evaporators 31 and 32 can be achieved simply and effectively. This allows high heat loads to be dissipated effectively through the parallel supply of both evaporators 31 and 32. If only moderate heat loads are present, an energy-saving sequential supply of the evaporators 31 and 32 can be implemented in step M3.

[0093] Although the present invention has been explained above by way of example, it is not limited to such embodiments and can be modified in many ways. For example, instead of the throttles 41, 42, 51, 52 designed as capillaries, one or more of the throttles 41, 42, 51, 52 described above can also be implemented as throttle valves. In addition, the valve arrangement 6 can alternatively or additionally include other multi-way valves connected in a cascade to represent the first, second, and third switching states described above.

[0094] In particular, combinations of the preceding examples are also conceivable. REFERENCE MARK 1 cooling compartment 2 freezer compartments 3 Refrigerant circuit 4 first throttle device 5 second throttle device 6 Valve arrangement 7 flow restrictors 8 Sensor system 9 Control 11 first compartment fan 12 second compartment fan 13 external fans 31 first evaporator 31A Input of the first evaporator 31B Outlet of the first evaporator 32 second evaporator 32A input of the second evaporator 32B Output of the second evaporator 33 compressors 33A Suction port 33B Pressure connection 34 liquefiers 34A Condenser Inlet 34B Condenser outlet 35 Check valve 37 shut-off valve 38 Suction line 41 first throttle of the first throttle device 42 second throttle of the first throttle device 51 first throttle of the second throttle device 52 second throttle of the second throttle device 60 rotary valve 61 Inlet of the rotary valve 62 first output of the rotary valve 63 second output of the rotary valve 64 third output of the rotary valve 65 perforated disc 81 first temperature sensor 82 second temperature sensor 100 refrigeration unit DB flow limiting circuit M procedure M1-M4 process steps M21, M22 verification steps QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2011-012885 A

[0007] JP 2005-164070 A

[0008] EP 3 447 407 A1

[0009]

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