Refrigeration system with heat pump function for a motor vehicle with a single low-pressure side sensor device

Abstract

Refrigeration system (10) with heat pump function for a motor vehicle, wherein the refrigeration system (10) comprises: a refrigerant compressor (12) connectable or connected to a primary line (14); a direct or indirect external heat exchanger (18), which is arranged in the primary strand (14); a first evaporator (22) arranged in the primary line (14); a first directly or indirectly acting heat exchanger, in particular a chiller (28), which is arranged fluidically parallel to the evaporator (22); and a refrigerant collector (24) arranged on the low-pressure side, wherein a single sensor device (pT2) is arranged downstream of the evaporator (22) and the further heat exchanger, in particular chiller (28), which is designed to detect the pressure and temperature of the refrigerant on the low-pressure side of the refrigeration system (10), characterized in that the single sensor device (pT2) is arranged upstream of the refrigerant collector (24).

Description

The invention relates to a refrigeration system, in particular with heat pump function, for a motor vehicle, wherein the refrigeration system comprises: a refrigerant compressor, which is connectable or connected to a primary train; an external heat exchanger, which acts directly or indirectly and is arranged in the primary train; a first evaporator, which is arranged in the primary train; a first directly or indirectly acting heat exchanger, in particular chiller, which is arranged fluidically parallel to the evaporator; and a refrigerant collector arranged on the low-pressure side.Refrigeration systems with a low-pressure-side refrigerant collector, which directly use waste heat from electrical (drive) components via the further heat exchanger, in particular chiller, and ambient heat via an external heat exchanger, are provided with pressure / temperature sensors at various points in the refrigerant circuit according to DE 10 2018 201 165 B3. In particular, two or more sensor devices for detecting pressure and / or temperature are regularly provided on the low-pressure side of the refrigeration system. Further refrigeration systems are known from DE 10 201 428 A1, DE 10 2015 007 564 A1, post-published DE 10 2019 135 056, DE 10 2018 201 945 A1 and DE 10 2018 213 232 A1. In this case, in particular on the low-pressure side, a pressure / temperature sensor is arranged in each case downstream of the evaporator or downstream of the further heat exchanger (chiller) and downstream of the refrigerant collector.DE 10 2019 203 292 A1 shows a refrigeration system according to the preamble of claim 1 with a single low-pressure-side sensor device.The object on which the invention is based is to specify a refrigeration system in which a simplified construction is achieved with substantially the same functionality.This object is achieved by a refrigeration system having the features of claim 1 and by a motor vehicle having the features of claim 9.A refrigeration system, in particular having an optional heat pump function, for a motor vehicle is therefore proposed, wherein the refrigeration system comprises: a refrigerant compressor which is connectable or connected to a primary train; a directly or indirectly acting external heat exchanger which is arranged in the primary train; a first evaporator which is arranged in the primary train; a first directly or indirectly acting heat exchanger, in particular chiller, which is arranged fluidically parallel to the evaporator; and a refrigerant collector arranged on the low-pressure side. It is provided here that downstream of the evaporator and the further heat exchanger, in particular chiller, a single sensor device is arranged which is configured to detect the pressure and the temperature of the refrigerant on the low-pressure side of the refrigeration system.By arranging a single sensor device for detecting pressure and temperature, a sensor device can be dispensed with compared with the known refrigeration systems, which simplifies the construction of the refrigeration system. It is pointed out that the single sensor device can have a single pressure sensor and a single temperature sensor or can be designed as a combined pressure / temperature sensor.According to the invention, in the refrigeration system, the single sensor device is arranged upstream of the refrigerant collector. In other words, the single sensor device is arranged in front of the refrigerant collector, in particular shortly or directly in front of the refrigerant collector. Here, immediately before the refrigerant collector can be understood to mean a distance which extends up to about 20 centimeters upstream of the refrigerant collector.The single sensor device can be arranged downstream of a branch, in which a line section on the outlet side of the evaporator and a line section on the outlet side of the further heat exchanger, in particular chiller, are connected to one another. In other words, the single sensor device is arranged after a combination of the refrigerant strings of evaporator and chiller.The refrigeration system can have a control device which is configured to carry out at least one of the following functions on the basis of detected pressure and / or temperature values from the single sensor device: monitoring a temporary, in particular briefly or long-term, overheating of the refrigerant for underflow detection; monitoring the minimum suction pressure for ice protection. Short-term overheating with accompanying underflow, which generally takes only a few seconds, is generally not critical for the operation of the refrigeration system, whereas long-term overheating with accompanying underflow of at least one to several minutes is disadvantageous and critical for the operation of the refrigeration system.During the monitoring and possibly prompt compensation or the decay of the temporary underflow, an overheating state can be taken into account in particular. Such an overheating state can occur, for example, in the event of load changes in the system to a higher power requirement; low load if the evaporator is operated solely in the cooling mode (AC mode); a heat pump mode or in a post-heating mode (reheater) with heat surplus.In this case, in the arrangement of the single sensor device downstream of the refrigerant collector, due to the transition of a steady-state operation into an at least temporarily dynamic (non-steady-state) operation of the refrigeration system in connection with the load change that has occurred and the release of additionally required refrigerant from the refrigerant collector into the circuit that has not yet been completed, a delay with respect to the reduction of the overheating state in the case of regular system operation must be taken into account. The process of supplying refrigerant from the accumulator into the active system or the circuit itself takes place with a time delay. The greater the load change, the more pronounced or longer is the time period until the regular, quasi-steady-state operation is restored with a substantially constant refrigerant mass flow.In the refrigeration system with the single low-pressure-side sensor device upstream of the refrigerant collector, the control device can be further configured to perform at least one of the following further functions based on detected pressure and / or temperature values:controlling the evaporator and / or the further heat exchanger, in particular chillers, in an AC dual mode;controlling the superheating of the evaporator if more cooling capacity is required at the further heat exchanger, in particular chiller;Regulation of the superheating of the further heat exchanger, in particular chillers, when more cooling capacity is required at the evaporator.If the single sensor device is arranged upstream of the refrigerant collector, the above-described functions with respect to overheating can be implemented without any appreciable delay. Accordingly, the monitoring and, if appropriate, the shutdown of temporary underflow via the overheating state can take place very quickly and accurately.In the refrigeration system with the single low-pressure-side sensor device upstream of the refrigerant collector, the control device can be configured to take into account at least one stored characteristic curve and / or at least one stored characteristic map, wherein the characteristic curve or the characteristic map comprises values for determining prevailing pressure levels, in particular suction pressure reduction, based on a pressure detected by the single sensor device and on a pressure loss contained in the characteristic curve or in the characteristic map, which occurs downstream from the single sensor device to the refrigerant compressor. The characteristic curve or the characteristic map serve in particular to achieve an improved quality with regard to the determination or estimation of target variables which are set on the system side. The aim here is that the respectively required or current pressures are determined at all operating points of the refrigeration system and, if necessary, a low-pressure limit is estimated or predicted.Furthermore, in the case of the refrigeration system, the control device can be configured to detect an underflow, in particular by means of the evaluated refrigerant state, downstream of the refrigerant collector, wherein a delaying effect of the refrigerant collector is estimated or determined by means of a characteristic diagram and / or by means of functions. It should be taken into account here that an underflow detection is detected more directly and thus more dynamically and possibly more sensitive by the sensor device arranged upstream of the refrigerant collector, so that the described damping or delaying effect by the refrigerant collector should be modeled by means of characteristic diagram and / or functions in order to set a final refrigerant state in the refrigeration system. In a simplified variant, alternatively, a characteristic curve can be used.The refrigeration system can further comprise: a secondary train which is connected or connectable to the refrigerant compressor; and a further heat exchanger which constitutes a heat source and acts directly or indirectly, in particular a heating register which is arranged in the secondary train.The refrigeration system can further comprise: a primary branch valve arranged between the refrigerant compressor and the outer heat exchanger; and a secondary branch valve arranged between the refrigerant compressor and the further heat exchanger, in particular heating register, constituting a heat source.A motor vehicle, in particular an at least partially electrically operated motor vehicle, can have a refrigeration system described above. In the case of an electric vehicle, efficient operation of the refrigeration system can lead to savings in power, so that a longer range of the electric vehicle can be achieved as a result. In particular, the refrigeration system presented here can also be used to monitor largely all operating states of the refrigeration system with only a single low-pressure-side sensor device for detecting pressure and temperature, as if the refrigeration system had at least two low-pressure-side pressure / temperature sensors.Further advantages and details of the invention are evident from the following description of embodiments with reference to the figures. The following shows: FIG. 1 shows a schematic and simplified circuit diagram of a refrigeration system for a motor vehicle; FIG. 2 shows a schematic and simplified circuit diagram of a refrigeration system for a motor vehicle.FIG. 1 shows an embodiment of a refrigeration system 10 for a motor vehicle in schematic and simplified form. The refrigeration system 10 comprises a refrigerant circuit 11 which can be operated both in a refrigeration system operation (also referred to as AC operation for short) and in a heat pump mode. In the embodiment shown, the refrigeration system 10 comprises a refrigerant compressor 12, an outer heat exchanger 18, an inner heat exchanger 20, an evaporator 22 and an accumulator or refrigerant collector 24. In particular, the outer heat exchanger 18 can be passed through bidirectionally in the embodiment shown.The evaporator 22 is shown here as a front evaporator for a vehicle by way of example. The evaporator 22 also represents further evaporators which are possible in a vehicle, such as for example rear evaporators, which can be arranged parallel to one another in terms of flow. In other words, the refrigeration system 10 thus comprises at least one evaporator 22.Downstream of the compressor 12 is a shut-off valve A4. An expansion valve AE 2 is provided upstream of the evaporator 22.Within the scope of this description, the section from the compressor 12 to the outer heat exchanger 18, to the inner heat exchanger 20 and to the evaporator 22 is referred to as the primary strand 14 in the entire refrigerant circuit 11 of the refrigeration system 10.The refrigeration system 10 further comprises a heating register 26 (also referred to as a heating condenser or heating gas cooler). Upstream of the heating register 26 is a shut-off valve A3. Downstream of the heating register 26 is a shut-off valve A1. Further, downstream of the heating register 26, an expansion valve AE4 is disposed.In the context of this description, the section from the compressor 12 to the heating register 26, to the expansion valve AE 4 and to a branch Ab 2 is referred to as the secondary branch 16 in the entire refrigerant circuit of the refrigeration system 10. The secondary line 16 comprises a heating branch 16.1, which extends from the shut-off valve A3 via the heating register 26 to the shut-off valve A1. The secondary train 16 further comprises a reheater branch 16.2 which is fluidically connectable upstream to the heating register 26 and downstream to the external heat exchanger 18. The secondary strand 16 or the reheat branch 16.2 opens into the primary strand 14 at a branch point Ab2.The refrigeration system 10 comprises a further evaporator or chiller 28. The chiller 28 can serve, for example, for cooling an electrical component of the vehicle, but also for implementing a water heat pump function using the waste heat from at least one electrical component. Upstream of the chiller 28, an expansion valve AE1 is connected.The refrigeration system 10 can also have an electrical heating element 30, which is designed, for example, as a high-voltage PTC heating element. The electric heating element 30 serves as an additional heater for an intake air flow L guided into the vehicle interior. In this case, the electric heating element 30 can be accommodated together with the heating register 26 and the evaporator 22 in an air conditioning unit 32. In this case, the electrical heating element 30 can be arranged downstream of the heating register 26.In FIG. 1, check valves R 1 and R 2 are also visible. Furthermore, some high-pressure-side sensors pT1, pT5, pT6 for detecting the pressure and / or temperature of the refrigerant are also shown. It is pointed out that the number of high-pressure-side sensors or their arrangement is shown here only by way of example. In the example shown, combined pressure / temperature sensors pT1, pT5 and pT6 are shown as sensors. However, it is equally conceivable for sensors which are separate from one another to be used for measuring pressure or temperature and, if appropriate, also to be arranged spatially separate from one another along the refrigerant lines.The refrigeration system 10 can be operated in different modes, which will be briefly described below.During the AC operation of the refrigerant circuit 11, the refrigerant compressed to high pressure flows from the refrigerant compressor 12 into the outer heat exchanger 18 with the shut-off valve A 4 open, from there it flows to the high-pressure section of the inner heat exchanger 20 and the fully open expansion valve AE 3. Via a branch point Ab 1, the refrigerant can flow to the expansion valve AE 2 and into the interior evaporator 22 (evaporator section 22.1). In parallel or alternatively, the refrigerant may flow into the chiller 28 via a branch point Ab 4 and the expansion valve AE 1 (chiller section 28.1). From the evaporator 22 and / or the chiller 28, the refrigerant flows on the low-pressure side into the accumulator 24 and through the low-pressure section of the internal heat exchanger 20 back to the compressor 12.In the AC mode, the heating branch 16.1 or the secondary branch 16 is shut off by means of the shut-off valve A3, so that hot refrigerant cannot flow through the heating register 26. To return refrigerant from the inactive heating branch 16.1, the shut-off element A5, which is designed as a shut-off valve, can be opened, so that the refrigerant can flow in the direction of the accumulator 24 via the shut-off element A5 and the nonreturn valve R2, with the shut-off element A2 simultaneously closed.In the heating operation of the refrigerant circuit 11, the shut-off valve A 4 is closed and the shut-off valve A 3 is opened, so that hot refrigerant can flow into the heating branch 16.1.To carry out the heating function by means of the chiller 28 for implementing a water heat pump operation, the refrigerant compressed by means of the refrigerant compressor 12 flows via the open shut-off valve A 3 into the heating register 26. The refrigerant then flows via the opened shut-off valve A 1 and the branch point Ab 1. It is expanded by means of the expansion valve AE 1 into the chiller 28 for absorbing waste heat of the electrical and / or electronic components arranged in a coolant circuit 28.2. In this heating function, the expansion valves AE3 and AE4 are closed, the shut-off valve A5 is closed, and the shut-off valve A2 is opened. In this case, refrigerant discharged in water heat pump operation can be extracted from a bidirectional branch 14.1 or the primary branch 14 via the shut-off valve A2 and fed to the accumulator 24 via the nonreturn valve R2.To carry out the heating function by means of the outer heat exchanger 18 as a heat pump evaporator, the refrigerant compressed by means of the refrigerant compressor 12 flows via the open shut-off valve A 3 for delivering heat to an inlet air stream L into the heating register 26, and is then expanded via the open shut-off valve A 1 by means of the expansion valve AE 3 into the outer heat exchanger 18 for absorbing heat from the ambient air. The refrigerant then flows via a heat pump return branch 15 to the accumulator 24 and back to the refrigerant compressor 12, and the expansion valves AE 1, AE 2 and AE 4 remain closed in the same way as the shut-off valve A 5.An indirect delta connection can be realized in that, when the shut-off valve A 1 is open, the refrigerant compressed by the refrigerant compressor 12 is expanded by means of the expansion valve AE 1 into the chiller 28, wherein at the same time no mass flow is generated on the coolant side, that is to say in the coolant circuit 28.2, that is to say, for example, the fluid used as coolant, such as water or water-glycol mixture, remains stationary on the coolant side of the chiller 28 or coolant does not actively flow through the chiller 28. The expansion valves AE 2, AE 3 and AE 4 remain closed in this switching variant.During a post-heating or re-heating operation, the supply air flow L supplied into the vehicle interior is first cooled by means of the evaporator 22 and is thus dehumidified. With the heat transferred to the refrigerant by evaporation and dehumidification and with the heat supplied to the refrigerant via the compressor 12, the supply air flow L can be completely or at least partially reheated by means of the heating register 26.For this purpose, the refrigeration system 10, in particular the air conditioning unit 32, has adjustable, in particular controllable and pivotable, temperature flaps 34 between the evaporator 22 and the heating register 26. In the illustrated example, left and right temperature doors 34L and 34R (shown schematically in FIG. 1 ) are disposed. The temperature doors 34L, 34R may be adjusted or pivoted between an open position, referred to as a 100% position, and a closed position, referred to as a 0% position. Alternatively, it is also possible to connect the temperature flaps 34R, 34L downstream of the heating register 26.In the 100% position, all of the supply air flow L flowing through the evaporator 22 is guided via the heating register 26 and heated before it can flow into the passenger compartment of the vehicle. In the 0% position, the entire supply air stream L flowing through the evaporator 22 flows in the bypass around the heating register 26 without heating and thus without heat absorption into the passenger compartment.In an x position of the temperature flaps 34L and 34R with 0%<x <100%, these temperature flaps are only partially opened, so that in each case only a partial air stream of the feed air stream L flowing through the evaporator 22 is guided via the heating register 26. This heated partial air flow can subsequently be mixed with the remaining, cooled and dehumidified partial air flow. The thus heated intake air flow L is supplied to the passenger compartment of the vehicle. By way of example, a 50% position indicates that the temperature flaps 34R and 34L are only half open, that is to say 50% open.On the low-pressure side of the refrigeration system 10, in particular downstream of the evaporator 22 and downstream of the chiller 28, a single sensor device pT 2 is arranged. In the example of FIG. 1, the sensor device pT 2 is arranged downstream of the refrigerant collector 24. In particular, the sensor device pT 2 is provided between the refrigerant collector 24 and the inner heat exchanger 20.The evaporator 22 and the chiller 28 have a respective section of the relevant evaporator section 22.1 or chiller section 28.1 arranged on the outlet side or downstream, which sections are connected to one another at the branch Ab2. The single sensor device pT 2 on the low pressure side is provided downstream of the branch Ab 2. This ensures that, regardless of whether refrigerant flows through the evaporator 22 or the chiller 28 alone or in combination, the pressure and the temperature of the refrigerant can be detected on the low-pressure side. In other words, the single sensor device pT 2 is arranged between the branch Ab 2 and the inner heat exchanger 20 (if present) or the refrigerant compressor 12.FIG. 2 shows an arrangement according to the invention of the single low-pressure-side sensor device pT 2. In this case, the sensor device pT 2 is arranged upstream of the refrigerant collector 24. In particular, the sensor device pT 2 can be arranged directly in front of the refrigerant collector 24. In this case, a distance between the sensor device pT 2 and the refrigerant collector can be, for example, up to 20 centimeters.In the example of FIG. 2, the sensor device pT 2 is likewise arranged downstream of the evaporator 22 and the chiller 28. In particular, the sensor device pT 2 is arranged downstream of the branch Ab 2, at which the evaporator section 22.1 and the chiller section 28.1 meet. In other words, the sensor device pT 2 is disposed between the branch Ab 2 and the refrigerant collector 24.In both examples of FIGS. 1 and 2, the refrigeration system 10 has a control device 50, which is configured to record the various operating states of the refrigeration system 10, which have been described above by way of example, but in particular to control or regulate them on the basis of the input values and setpoint variables. In this case, the control device 50 can receive and process sensor data, calculate and / or estimate further operating parameters and actuate the refrigerant compressor or valve devices and the like of the refrigeration system.Taking into account the structural design with a single low-pressure-side sensor device pT 2, the control device 50 can be configured to carry out at least one of the following functions on the basis of detected pressure and / or temperature values from the single low-pressure-side sensor device pT 2: monitoring overheating, synonymous with systems with a refrigerant collector 24 arranged on the low-pressure side with an underfill, which in turn can occur either temporarily or permanently; and / or monitoring the minimum suction pressure for anti-icing purposes.During the monitoring and optionally regulating down of the temporary overheating condition, an underflow condition can be taken into account. Such an overheating and thus underflow condition can occur, for example, during load changes in the system to a higher power requirement; low load when the evaporator is operated solely in cooling operation (AC operation); heat pump operation or after-heating operation (reheater) with heat surplus.In this case, in the arrangement of the single sensor device pT 2 downstream of the refrigerant collector 24 (FIG. 1 ), due to the transition from a steady-state operation to an at least temporarily dynamic (non-steady-state) operation of the refrigeration system 10 in connection with the load change that has occurred and the release of additionally required refrigerant from the refrigerant collector 24 into the circuit that has not yet been completed, a delay with respect to the reduction of the overheating state during regular system operation must be taken into account. The process of supplying refrigerant from the accumulator 24 into the active system or the circuit 11 itself takes place with a time delay. The greater the load change, the more pronounced or longer the time period until the regular, quasi-steady-state operation is restored, with a substantially constant refrigerant mass flow.In the refrigeration system 10 with the single low-pressure-side sensor device pT 2 upstream of the refrigerant collector 24 (FIG. 2 ), the control device 50 can be further configured to carry out at least one of the following further functions on the basis of detected pressure and / or temperature values:controlling the evaporator 22 and / or the further heat exchanger,in particular, chillers 28 in dual AC mode;controlling the superheating of the evaporator 22 if more cooling capacity is required at the further heat exchanger, in particular chiller 28;Regulation of the superheating of the further heat exchanger, in particular chiller 28, if more cooling capacity is required at evaporator 22.If the single sensor device pT 2 is arranged upstream of the refrigerant collector 24 (FIG. 2 ), the functions described above with respect to overheating can be implemented without any appreciable delay. Accordingly, the monitoring and, if appropriate, the shutdown of temporary underflow via the overheating state can take place very quickly and accurately. In the extreme case, which corresponds, for example, to a permanently occurring overheating, which is measured, for example, at greater than 5 K, and unsuccessful controller intervention in order to eliminate this standard operating deviation, the cooling system 10 is shut down as a result.In the refrigeration system 10 with the single low-pressure-side sensor device pT 2 upstream of the refrigerant collector 24 (FIG. 2 ), the control device 50 can be configured to take into account at least one stored characteristic map, wherein the characteristic map comprises values for determining a suction pressure decrease based on a pressure detected by the single sensor device and on a pressure loss contained in the characteristic map, which occurs downstream of the single sensor device pT 2 to the refrigerant compressor 12.Furthermore, in the refrigeration system 10, the control device 50 can be configured to detect an underflow downstream of the refrigerant collector 24, wherein a delaying effect of the refrigerant collector 24 is estimated by means of a characteristic diagram and / or by means of functions. It should be taken into account here that an underflow detection is detected with the sensor device pT 2 (FIG. 2 ) arranged upstream of the refrigerant collector 24 more dynamically and possibly more sensitively, so that the described damping or delaying effect by the refrigerant collector 24 arranged downstream should be modeled by means of characteristic diagram and / or functions.By means of the refrigeration system 10 presented here with a single low-pressure-side sensor device pT 2, at least one pressure temperature sensor can be saved compared to known configurations of refrigeration systems for motor vehicles, which has a positive effect on the costs, package requirements and weight of such a refrigeration system. Furthermore, despite the use of a single low-pressure-side sensor device pT 2, it is possible to represent all essential functions or provide them by means of the control device 50 of the refrigeration system 10.

Claims

Refrigeration system (10) with heat pump function for a motor vehicle, wherein the refrigeration system (10) comprises: a refrigerant compressor (12), which is connectable or connected to a primary line (14); a directly or indirectly acting external heat exchanger (18), which is arranged in the primary line (14); a first evaporator (22), which is arranged in the primary line (14); a first directly or indirectly acting heat exchanger, in particular chiller (28), which is arranged fluidically parallel to the evaporator (22); and a refrigerant collector (24) arranged on the low-pressure side, wherein a single sensor device (pT2) is arranged downstream of the evaporator (22) and the further heat exchanger, in particular chiller (28), which is configured to detect the pressure and the temperature of the refrigerant on the low-pressure side of the refrigeration system (10), characterized in that the single sensor device (pT2) is arranged upstream of the refrigerant collector (24).Refrigeration system (10) according to claim 1, characterised in that the single sensor device (pT2) is arranged downstream of a branch (Ab2), in which an outlet-side line section (22.1) of the evaporator (22) and an outlet-side line section (28.1) of the further heat exchanger, in particular chiller (28), are connected to one another.Refrigeration system (10) according to claim 1 or 2, characterised in that it has a control device (50) which is configured to carry out at least one of the following functions on the basis of detected pressure and / or temperature values from the single sensor device (pT2): monitoring a temporary, in particular briefly or long-term, overheating of the refrigerant for underflow detection; monitoring the minimum suction pressure for ice protection.Refrigeration system (10) according to claim 3, characterised in that the control device (50) is configured to carry out at least one of the following further functions on the basis of detected pressure and / or temperature values of the single sensor device (pT2) arranged upstream of the refrigerant collector (24): regulation of the evaporator (22) and / or of the further heat exchanger, in particular chiller (28), in an AC dual mode; regulation of the superheating of the evaporator (22) if more cooling capacity is required at the further heat exchanger, in particular chiller (28); regulation of the superheating of the further heat exchanger, in particular chiller (28) if more cooling capacity is required at the evaporator (22).Refrigeration system (10) according to claim 3 or 4, characterised in that the control device (50) is configured to take into account at least one stored characteristic curve and / or at least one stored characteristic diagram, wherein the characteristic curve or the characteristic diagram comprises values for determining prevailing pressure levels, in particular suction pressure reduction, based on a pressure detected by the single sensor device and a pressure loss contained in the characteristic curve or in the characteristic diagram, which occurs downstream from the single sensor device (pT2) to the refrigerant compressor (12).Refrigeration system (10) according to claim 5, characterised in that the control device (50) is further configured to detect an underflow downstream of the refrigerant collector (24), wherein a delaying effect of the refrigerant collector (24) is estimated or determined by means of a characteristic diagram and / or by means of functions.Refrigeration system (10) according to one of the preceding claims, characterized in that it further comprises: a secondary train (16), which is connected or can be connected to the refrigerant compressor (12); and a further heat exchanger, which constitutes a heat source and acts directly or indirectly, in particular a heating register (26), which is arranged in the secondary train (16).Refrigeration system (10) according to claim 7, characterised in that it further comprises: a primary branch valve (A4) arranged between the refrigerant compressor (12) and the outer heat exchanger (18); a secondary branch valve (A3) arranged between the refrigerant compressor (12) and the further heat exchanger, in particular heating register (26), representing a heat source.Motor vehicle, in particular at least partially electrically driven motor vehicle, having a cooling system (10) according to one of the preceding claims.

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