Refrigerant circuit with a refrigerant substitute, motor vehicle and method for operating the refrigerant circuit

Abstract

The invention relates to a refrigerant circuit (10) for a motor vehicle, wherein the refrigerant circuit (10) is designed for operation with a refrigerant in the form of at least one fluorinated hydrocarbon. A compressor (14) is configured for conveying the refrigerant to a heat exchanger (16), and a control device (30) is configured for controlling the compressor (14). The refrigerant circuit (10) is filled with a substitute substance other than fluorinated hydrocarbons, wherein the refrigerant circuit (10) has at least one sensor (26, 28) by means of which the substitute substance can be distinguished from the at least one fluorinated hydrocarbon. The control device (30) is configured to prevent the compressor (14) from being started up if the presence of the substitute substance in the refrigerant circuit (10) is detected by means of the at least one sensor (26, 28).Furthermore, the invention relates to a motor vehicle with such a refrigerant circuit (10) and a method for operating the refrigerant circuit (10).

Description

[0001] The invention relates to a refrigerant circuit for a motor vehicle, wherein the refrigerant circuit is designed for operation with a refrigerant in the form of at least one fluorinated hydrocarbon. The refrigerant circuit includes a compressor for conveying the refrigerant to a heat exchanger of the refrigerant circuit and a control device for controlling the compressor. Furthermore, the invention relates to a motor vehicle with such a refrigerant circuit and a method for operating the refrigerant circuit.

[0002] Refrigerant circuits are used in vehicles, for example, which are designed for operation with a refrigerant in the form of a fluorinated hydrocarbon. For instance, the refrigerant R134, a fluorinated hydrocarbon in the form of tetrafluoroethane, or R1234yf, a fluorinated hydrocarbon in the form of tetrafluoropropene, can be used. Furthermore, refrigerant circuits can be designed for operation with the refrigerant R744 (carbon dioxide, CO2).

[0003] When manufacturing a refrigerant circuit, the respective refrigerant is typically added to the circuit at the end of the production process or during the production process itself. Afterwards, the functionality of the refrigerant circuit can be checked during a system commissioning or test run.

[0004] For filling the respective refrigerant circuit with the refrigerant matched to the refrigerant circuit, respective filling ports or filling connections can be provided on the refrigerant circuit, which, due to their design, ensure that only a filling device, by means of which the refrigerant suitable for the refrigerant circuit can be filled into the refrigerant circuit, can be connected to the refrigerant circuit at all.

[0005] Once the refrigerant circuit is filled with refrigerant, it is generally assumed that it is the correct refrigerant, i.e., suitable for operation of the circuit. The refrigerant circuit can then be started, i.e., put into operation.

[0006] German patent DE 10 2009 027 065 A1 describes a method for operating an air conditioning system for a motor vehicle. The air conditioning system has a refrigerant circuit and a device for determining a characteristic value for the type of refrigerant present in the circuit. Based on a comparison of this characteristic value with stored data, a diagnostic check is performed to determine whether a refrigerant not approved for use in the air conditioning system or potentially harmful is present. Depending on the results of this check, a warning signal is generated for the driver or the operation of the air conditioning system is automatically interrupted.

[0007] DE 694 31 897 T2 describes a method for testing a refrigerant, which should be an uncontaminated first refrigerant compound, for contamination by a second refrigerant compound.

[0008] DE 42 13 270 A1 describes a device for identifying and distinguishing between two different types of refrigerant.

[0009] US 10 969 148 B2 describes a system for detecting refrigerant contamination in an HVACR system.

[0010] EP 2 762 337 B1 describes a refrigerant circuit of a vehicle in which a refrigerant in the form of a chlorofluorocarbon (CFC) is replaced by a refrigerant in the form of a fluorinated hydrocarbon (HFC). A control unit can be connected to a display that shows the information that the refrigerant circuit has been updated in this way.

[0011] Furthermore, EP 4 027 074 A1 describes a refrigerant circuit with a leakage sensor which can detect the presence of a first refrigerant and a second refrigerant.

[0012] The object of the present invention is to create a refrigerant circuit of the type mentioned above in which operational damage can be easily avoided, and to provide a motor vehicle with such a refrigerant circuit as well as a corresponding method for operating a refrigerant circuit.

[0013] This problem is solved by a refrigerant circuit with the features of claim 1, a motor vehicle with the features of claim 8, and a method with the features of claim 9. Advantageous embodiments with expedient further developments of the invention are specified in the dependent claims and in the following description.

[0014] The refrigerant circuit according to the invention for a motor vehicle is designed for operation with a refrigerant in the form of at least one fluorinated hydrocarbon. A compressor of the refrigerant circuit serves to pump the refrigerant to a heat exchanger of the refrigerant circuit. The refrigerant circuit has a control device for controlling the compressor. The refrigerant circuit is filled with a substitute substance other than fluorinated hydrocarbons, wherein the refrigerant circuit has at least one sensor by means of which the substitute substance can be distinguished from the at least one fluorinated hydrocarbon. The control device is designed to prevent the compressor from being started if the presence of the substitute substance in the refrigerant circuit is detected by the at least one sensor.

[0015] The control device is designed to activate at least one fan in the refrigerant circuit when the compressor is shut down. This fan is designed to circulate air that can be temperature-controlled during operation of the refrigerant circuit. This ensures that, particularly when the refrigerant circuit is used in a motor vehicle, ventilation of, for example, the passenger compartment continues even if the control device prevents the compressor from starting.

[0016] Furthermore, at least one fan can be designed to dissipate excess heat from a radiator or similar component of the vehicle. In this configuration, the radiator and a heat exchanger of the refrigerant circuit can be arranged in a single assembly, which can be supplied with air by the same fan. This allows the radiator to be cooled by operating the fan, even though no heat needs to be dissipated from the refrigerant circuit's heat exchanger itself, because the compressor is not running.

[0017] Therefore, it is advantageous that the control device is designed to bring about the commissioning of at least one fan of the refrigerant circuit, despite the interrupted operation of the compressor.

[0018] At least one sensor can therefore be used to detect that the refrigerant circuit is filled with a substitute that is different from fluorinated hydrocarbons. In other words, the substitute is a pure substance or a mixture that is neither formed from nor contains a fluorinated hydrocarbon.

[0019] The refrigerant circuit is designed for operation with a refrigerant that is a fluorinated hydrocarbon, for example, with refrigerant R1234yf (a fluorinated hydrocarbon in the form of tetrafluoropropene) and / or with refrigerant R134 (a fluorinated hydrocarbon in the form of tetrafluoroethane). It would therefore be detrimental to start the refrigerant circuit by having the compressor begin circulating the substitute refrigerant through the circuit.

[0020] The refrigerant circuit therefore has at least one sensor that makes it possible to distinguish the substitute from the at least one fluorinated hydrocarbon. This allows the presence of the substitute in the refrigerant circuit to be detected by means of this sensor. This, in turn, causes the control unit to prevent the compressor from starting up.

[0021] This prevents damage that could otherwise occur when the refrigerant circuit is operated with the substitute refrigerant, as the compressor circulates the substitute refrigerant through refrigerant lines and other components of the circuit. Consequently, in a refrigerant circuit where the control unit is designed to prevent the compressor from starting when the presence of the substitute refrigerant is detected by the sensor, operational damage is easily avoided.

[0022] Nevertheless, it is ensured that the refrigerant circuit does not remain empty. Filling the refrigerant circuit with the substitute is particularly advantageous to prevent the unwanted introduction of contaminants or similar substances into the refrigerant circuit.

[0023] For example, it may be planned that the refrigerant circuit is exported to a country of use or importing country where the filling with the refrigerant in the form of the fluorinated hydrocarbon is to take place, i.e., to a country where the substitute substance is to be replaced by the refrigerant in the form of the fluorinated hydrocarbon.

[0024] In the importing country where the refrigerant circuit is to be operated with the refrigerant in the form of the fluorinated hydrocarbon, the use of the fluorinated hydrocarbon may be permitted. Conversely, in a production country where the refrigerant circuit is manufactured and filled with the substitute, the use of the refrigerant in the form of the fluorinated hydrocarbon may be prohibited.

[0025] In such a situation, it is particularly advantageous that the refrigerant circuit is not empty during transport from the country of production, where the refrigerant circuit is manufactured and filled with the substitute, to the country of use, where the refrigerant circuit is to be operated. This is especially beneficial for ensuring the refrigerant circuit's leak tightness and / or for being able to verify its leak tightness.

[0026] For example, during transport, at least one sensor can detect that the substitute refrigerant is present in the refrigerant circuit. The control unit can then ensure that the refrigerant circuit does not start up without being filled with the refrigerant intended for operation.

[0027] Nevertheless, the refrigerant circuit filled with the substitute substance, or the vehicle containing the refrigerant circuit, can be exported to the country of use or importing country without any problems, for example, with regard to regulations or requirements concerning the use of fluorinated hydrocarbons. This is advantageous.

[0028] Furthermore, it may occur that a problem arises with the refrigerant circuit in the country of use or operation, where the refrigerant circuit is permitted to be operated with the refrigerant in the form of the fluorinated hydrocarbon. This necessitates re-importation to the country of production, where the refrigerant circuit was manufactured or at least filled with the substitute. Before such re-importation to the country of production, the substitute can again be added to the refrigerant circuit. This allows for a smooth import into the country of production, where the use of the fluorinated hydrocarbon may be prohibited. Subsequently, repairs to the refrigerant circuit can be carried out or the problem resolved in the country of production. This is advantageous.

[0029] The latter applies in particular if the country of production has a higher level of technical expertise with regard to troubleshooting, repairing or maintaining the refrigerant circuit than the country of use or operation of the refrigerant circuit.

[0030] If the refrigerant circuit is installed in the vehicle, the vehicle can continue to be operated without problems even when the refrigerant circuit is filled with the substitute refrigerant. Only the compressor's operation is prevented by the control unit in this case. The continued usability of the vehicle in other respects is advantageous.

[0031] The refrigerant circuit can also be used in areas other than automotive engineering. Consequently, the refrigerant circuit can be advantageously used in a variety of stationary applications as well as other mobile applications. These mobile applications can include, in particular, any type of vehicle, i.e., land vehicles, watercraft, and aircraft. In all these applications, the control unit prevents the compressor from starting and thus the refrigerant circuit from operating when the presence of the substitute refrigerant in the circuit is detected by at least one sensor. This is advantageous.

[0032] The substitute or refrigerant substitute, which replaces the fluorinated hydrocarbon originally intended for operation in the refrigerant circuit, can be used, for example, during transport from the country of production, where the refrigerant circuit is manufactured and / or filled with the substitute, to the country of use. In the country of use, the substitute can then be replaced with the refrigerant in the form of the fluorinated hydrocarbon.

[0033] However, as long as the substitute or replacement substance is present in the refrigerant circuit, this can be clearly detected by at least one sensor. The control unit then ensures that the refrigerant circuit does not start up or the compressor is not commissioned.

[0034] The substitute substance can therefore fulfill its purpose well, particularly during a transitional period that is preferable for transport from the country of production to the country of use. This applies especially if the use of the fluorinated hydrocarbon as a refrigerant is permitted in the country of use or importing, while its use as a refrigerant is prohibited in the country of production.

[0035] The same applies if such a prohibition of use is valid not only in a single country or state, but in a group encompassing several countries or states, such as the European Union. In this case, exporting the refrigerant circuit filled with the substitute substance to a country outside the European Union may be permissible, provided that the use of the refrigerant in the form of the fluorinated hydrocarbon is not prohibited in that country outside the European Union. Consequently, the refrigerant circuit has a very wide range of applications.

[0036] Preferably, the substitute material has at least one gas phase. In particular, the substitute material can be a gas or a gas mixture. Additionally, the substitute material can contain a liquid phase. Such a substitute material, which has at least one gas phase, is particularly well suited to replacing or substituting the refrigerant in the form of the fluorinated hydrocarbon in the refrigerant circuit. This is because, during operation of the refrigerant circuit with the refrigerant in the form of the fluorinated hydrocarbon, the fluorinated hydrocarbon is also present in the gas phase, at least in parts of the refrigerant circuit.

[0037] Preferably, the substitute substance in the refrigerant circuit is under a pressure higher than the pressure in the surrounding environment. This reliably prevents substances from entering the refrigerant circuit from the surrounding environment while the circuit is filled with the substitute substance. This is advantageous with regard to preventing contamination of the refrigerant circuit components by such an ingress of unwanted substances.

[0038] In particular, when nitrogen (N2) is used as the substitute or refrigerant substitute, which is at room temperature in the refrigerant circuit under a pressure greater than the pressure in the environment of the refrigerant circuit, the substitute can be very easily and reliably distinguished from a refrigerant which is a fluorinated hydrocarbon.

[0039] At least one sensor can be part of an analysis device of the refrigerant circuit, the analysis device being designed to identify the substitute. This allows for very precise detection of the presence of the substitute in the refrigerant circuit.

[0040] For example, the analytical instrument can be designed to identify the substitute based on its thermal conductivity. In particular, if the thermal conductivity of the substitute differs significantly from that of the refrigerant containing at least one fluorinated hydrocarbon, the substitute can be easily distinguished from the fluorinated hydrocarbon. This is advantageous.

[0041] Additionally or alternatively, the analytical instrument can be designed to identify the chemical composition of the substitute. For example, the analytical instrument can be designed to determine, at least qualitatively, the molecules forming the substitute. This leads to a very reliable identification of the substitute and also to good differentiation between the substitute and the fluorinated hydrocarbon. This distinction can be made very easily using the analytical instrument.

[0042] The at least one sensor can include an evaluation unit configured to determine the presence of the substitute in the refrigerant circuit by evaluating at least one measured quantity detectable by the sensor. The evaluation unit is configured to communicate with the control unit. In other words, the at least one sensor can integrate a function for detecting the substitute or its presence in the refrigerant circuit.

[0043] This is particularly advantageous when an existing sensor in the refrigerant circuit is to be replaced by the sensor in the refrigerant circuit that includes the evaluation unit. After such a replacement, it can be ensured that the control unit prevents the compressor from starting up after detecting the presence of the replacement refrigerant in the circuit.

[0044] In particular, retrofitting the refrigerant circuit with at least one sensor that includes the evaluation unit is therefore particularly easy. For example, the evaluation unit can be provided by a microprocessor, which can be integrated into the at least one sensor.

[0045] Additionally or alternatively, the at least one sensor can be configured to communicate at least one measured variable detectable by the sensor to the control unit. The control unit is then configured to determine the presence of the substitute substance in the refrigerant circuit by evaluating this at least one measured variable. This is particularly advantageous if at least one sensor already present in the refrigerant circuit is to be used to detect the presence of the substitute substance, so that the substitute substance can be distinguished from the at least one fluorinated hydrocarbon. In this case, only the control unit, which can be configured, for example, as the control device for the refrigerant circuit, needs to be configured to evaluate the at least one measured variable in order to prevent the compressor from starting up.

[0046] Preferably, the at least one sensor is configured as a pressure sensor and / or a temperature sensor. This is based on the understanding that at least one pressure sensor and / or at least one temperature sensor may already be provided in the refrigerant circuit to monitor its operation. If at least one such sensor, which is already provided, is used to detect the presence of the substitute in the refrigerant circuit and to distinguish the substitute from the fluorinated hydrocarbon, it is particularly easy to ensure that the compressor is not started when the refrigerant circuit is filled with the substitute.

[0047] For example, the control unit may contain characteristic curves that indicate a relationship between the pressure and temperature of the refrigerant in the form of the fluorinated hydrocarbon on the one hand, and the substitute on the other. Using such characteristic curves, the substitute and the at least one fluorinated hydrocarbon can be easily distinguished from each other.

[0048] Preferably, the at least one sensor is configured to detect at least one measured quantity by which the refrigerant, in the form of the at least one fluorinated hydrocarbon, can be identified. This makes it particularly easy to distinguish the substitute from the at least one fluorinated hydrocarbon.

[0049] For example, the at least one fluorinated hydrocarbon can be very easily identified by determining its pressure at a specific temperature or its temperature at a specific pressure, as can the substitute. In particular, it is advantageous if such pressure and temperature values ​​for the substitute and for the at least one fluorinated hydrocarbon are clearly different from each other. This allows it to be very easily determined, using at least one sensor, whether the substitute is present in the refrigerant circuit.

[0050] The motor vehicle according to the invention has a refrigerant circuit according to the invention. It is advantageous that damage to the refrigerant circuit caused by its operation can be avoided if the presence of the substitute refrigerant in the circuit is detected by means of at least one sensor. In this case, the control unit prevents the compressor from being started.

[0051] In the inventive method for operating a refrigerant circuit for a motor vehicle, the refrigerant circuit is designed for operation with a refrigerant in the form of at least one fluorinated hydrocarbon. A compressor of the refrigerant circuit is designed to pump the refrigerant to a heat exchanger of the refrigerant circuit. A control device of the refrigerant circuit controls the compressor. The refrigerant circuit is filled with a substitute substance other than fluorinated hydrocarbons. The refrigerant circuit has at least one sensor by which the substitute substance can be distinguished from the at least one fluorinated hydrocarbon. If the presence of the substitute substance in the refrigerant circuit is detected by the at least one sensor, the control device prevents the compressor from being started.When the compressor is not operating, the control device causes at least one fan of the refrigerant circuit to be put into operation, wherein the at least one fan is designed to convey air which can be temperature-controlled during the operation of the refrigerant circuit.

[0052] This method easily avoids damage that can occur when operating the refrigerant circuit with a substitute not designed for this purpose. This is advantageous.

[0053] The advantages and preferred embodiments described for the refrigerant circuit according to the invention also apply to the motor vehicle according to the invention and to the method according to the invention, and vice versa.

[0054] The invention therefore also includes further developments of the motor vehicle and the method according to the invention, which have features as already described in connection with the further developments of the refrigerant circuit according to the invention. For this reason, the corresponding further developments of the motor vehicle and the method according to the invention are not described again here.

[0055] The motor vehicle according to the invention is preferably designed as a motor vehicle, in particular as a passenger car or truck, or as a passenger bus.

[0056] The invention therefore also includes combinations of the features of the described embodiments. The invention thus also includes realizations that each exhibit a combination of the features of several of the described embodiments, provided that the embodiments have not been described as mutually exclusive.

[0057] Exemplary embodiments of the invention are described below. Shown are: Fig. 1 schematically a refrigerant circuit for a motor vehicle in which sensors determine whether the refrigerant circuit is filled with a substitute substance, wherein the substitute substance replaces a refrigerant intended for the operation of the refrigerant circuit in the form of a fluorinated hydrocarbon; Fig. 2 schematically an analysis device of the refrigerant circuit, which is designed to identify the substitute substance; Fig. 3 schematically a sensor of the refrigerant circuit for recording the measured quantities describing the substitute substance, wherein the sensor has an evaluation device; Fig. 4 characteristic curves which indicate a relationship between a temperature of the substitute and a corresponding pressure of the substitute, as well as between a temperature of the refrigerant in the form of the fluorinated hydrocarbon and a pressure of the refrigerant present at the respective temperature of the refrigerant; and Fig. 5 schematically a motor vehicle which the refrigerant circuit according to Fig. 1.

[0058] The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual features of the invention that can be considered independently of one another, each of which also develops the invention independently of one another. Therefore, the disclosure is intended to encompass combinations of the features of the embodiments other than those shown. Furthermore, the described embodiments can also be supplemented by further features of the invention already described.

[0059] In the figures, the same reference symbols designate elements with the same function.

[0060] In Fig. Figure 1 schematically shows a refrigerant circuit 10 as it is used in a motor vehicle 12 (compare Fig. 5) can be used, for example, as part of the air conditioning system of the motor vehicle 12. The refrigerant circuit 10 can additionally or alternatively be designed for heat pump operation.

[0061] The refrigerant circuit 10 comprises a compressor 14, which is designed to pump a refrigerant to a heat exchanger, for example, in the form of a condenser 16 of the refrigerant circuit 10. During operation of the refrigerant circuit 10, the refrigerant condensed in the condenser 16 flows from the condenser 16 to an expansion device 18, by means of which the refrigerant is expanded during operation of the refrigerant circuit 10. The expanded refrigerant is fed to an evaporator 20 of the refrigerant circuit 10. The refrigerant evaporating in the evaporator 20 is then drawn back in by the compressor 14. Refrigerant lines 22, via which the aforementioned components of the refrigerant circuit 10 are fluid-tightly coupled to one another, are arranged in Fig. 1. For the sake of clarity, only a general reference symbol is used.

[0062] The in Fig. The refrigerant circuit 10 shown is designed for operation with a refrigerant in the form of a fluorinated hydrocarbon, for example, for operation with R1234yf or with R134. It may be provided that the motor vehicle 12, which contains the refrigerant circuit 10 according to Fig. 1, is produced in a country where the use of fluorinated hydrocarbons, such as perfluorinated alkylenes or polyfluorinated alkylenes, is prohibited. Therefore, it may be impermissible to fill refrigerant circuit 10 with the refrigerant in the form of the fluorinated hydrocarbon for which refrigerant circuit 10 is actually designed.

[0063] In contrast, in a country of use or importing where the motor vehicle 12, with its refrigerant circuit 10, is to be used, the use of fluorinated hydrocarbons as a refrigerant in the refrigerant circuit 10 may be permissible. However, it would be technically disadvantageous to export the motor vehicle 12 from the country of production to the importing country, recipient country, or country of use with an empty, i.e., unfilled, refrigerant circuit 10.

[0064] Therefore, in this case, the refrigerant circuit 10, in particular the refrigerant lines 22 as well as the compressor 14, the condenser 16, the expansion device 18 and the evaporator 20, is filled with a substitute substance which is different from fluorinated hydrocarbons. For example, a gas such as nitrogen (N2) can be used as the substitute substance.

[0065] The substitute substance is preferably located in the refrigerant circuit 10 at a pressure which is greater than the pressure in an environment 24 of the refrigerant circuit 10 (compare Fig. 1).

[0066] The present measure prevents the refrigerant circuit 10 from being put into operation as long as it is filled with the substitute substance and not with the refrigerant for which it is actually designed. For this purpose, the refrigerant circuit 10 has at least one sensor by which the substitute substance can be distinguished from the fluorinated hydrocarbon.

[0067] Examples include: Fig. 1 as the at least one sensor, a pressure sensor 26 and a temperature sensor 28, is shown. The in Fig. The arrangement of the pressure sensor 26 and the temperature sensor 28 in the refrigerant circuit 10 shown in Figure 1 is to be understood as schematic only. For example, the pressure sensor 26 can be used to measure the refrigerant pressure downstream of the condenser 16 and upstream of the expansion device 18. The pressure sensor 26 can be used to measure the pressure of the refrigerant downstream of the condenser 16 and upstream of the expansion device 18. Fig. The temperature sensor 28 shown as an example can, for instance, measure the temperature of the substitute material downstream of the evaporator 20 or within the evaporator 20, and thus upstream of the compressor 14. However, other or further possibilities for placing the at least one sensor in the refrigerant circuit 10 are also possible.

[0068] Measurements acquired by at least one sensor, for example in the form of the pressure sensor 26 and the temperature sensor 28, can be supplied to a control unit 30 of the refrigerant circuit 10. The control unit 30, which is designed, for example, as a control device for the refrigerant circuit 10, is configured to control the compressor 14.

[0069] In this case, the control device 30 prevents the compressor 14 from starting up if at least one sensor, for example the pressure sensor 26 and the temperature sensor 28, detects that the substitute refrigerant is present in the refrigerant circuit 10 or that the refrigerant circuit 10 is filled with the substitute refrigerant. This prevents the refrigerant circuit 10 from starting up or operating as long as the refrigerant circuit 10 does not contain the refrigerant intended for its operation in the form of the fluorinated hydrocarbon or is filled with this refrigerant.

[0070] The substitute material is selected in such a way that, by means of at least one sensor, i.e., for example, based on the measured quantities detectable by the pressure sensor 26 and the temperature sensor 28, the substitute material can be clearly distinguished from the refrigerant in the form of the fluorinated hydrocarbon. This is intended to demonstrate with reference to Fig. 4 will be explained.

[0071] In Fig. Figure 4 shows a first characteristic curve 32, which indicates a relationship between a temperature of the substitute and a pressure of the substitute. The temperature is plotted on an abscissa 34 of a graph in Fig. The pressure on ordinate 36 of the graph is given in graph 4. For example, the substitute material located in refrigerant circuit 10 may be at room temperature, i.e., for example, at a temperature of approximately 22°C. At this temperature, the substitute material exhibits the following properties according to the graph shown in graph 4. Fig. The first characteristic curve 32 shown in section 4 exhibits a pressure of approximately 2 bar.

[0072] Furthermore, in Fig. Figure 4 shows another characteristic curve 38, which indicates the relationship between the pressure of a refrigerant in the form of a fluorinated hydrocarbon and the temperature of the refrigerant. For example, the further characteristic curve 38, which indicates the relationship between pressure and temperature, can represent the conditions for the refrigerant R1234yf. For this refrigerant, the following applies: Fig. As can be seen from the graph shown in section 4, and from the further characteristic curve 38, the refrigerant has a pressure of approximately 6 bar at a temperature of approximately 22°C.

[0073] The characteristic curves 32 and 38 thus allow for a very simple and unambiguous differentiation between the refrigerant in the form of the fluorinated hydrocarbon and the substitute, and vice versa. For this purpose, the characteristic curves 32 and 38 can, for example, be stored in the control unit 30. This makes it particularly easy to distinguish the substitute from the fluorinated hydrocarbon and to detect the presence of the substitute in the refrigerant circuit 10.

[0074] Additionally or alternatively, it is possible that the refrigerant circuit 10 has an analysis device 40, which is schematically shown in Fig. Figure 2 shows a sensor 42 belonging to the analysis device 40. Fig. Figure 2 is also shown schematically. The sensor 42 can be configured to determine the presence of the substitute substance in the refrigerant circuit 10 based on measured parameters of the substitute substance detectable by the sensor 42. Furthermore, the sensor 42 can be configured to detect the refrigerant in the form of the fluorinated hydrocarbon based on corresponding measured parameters.

[0075] For example, the analytical device 40 can be configured to distinguish the substitute from the refrigerant in the form of the fluorinated hydrocarbon based on its conductivity, in particular its thermal conductivity. Additionally or alternatively, the analytical device 40 can be configured to determine the molecular composition of the substitute on the one hand and the refrigerant in the form of the fluorinated hydrocarbon on the other. In this way, the substitute can be very reliably distinguished from the fluorinated hydrocarbon, and the presence of the substitute in the refrigerant circuit 10 can be determined.

[0076] The analysis unit 40 is designed to communicate with the control unit 30 in a manner not shown in detail herein.

[0077] Furthermore, in Fig. Figure 3 schematically shows a sensor 44 which is installed in the refrigerant circuit 10 according to Fig. 1 can be integrated, and by means of which the substitute can be distinguished from the at least one fluorinated hydrocarbon. Here, the sensor 44 comprises an evaluation unit 46.

[0078] The evaluation unit 46 is designed to determine the presence of the substitute substance in the refrigerant circuit 10 by evaluating measured variables detectable by means of the sensor 44. As described for the analysis unit 40, the evaluation unit 46 is also designed to communicate with the control unit 30.

[0079] For example, the in Fig. The sensor 44 shown in Figure 3 is designed to detect the pressure and / or temperature of the substitute substance located in the refrigerant circuit 10. The function of detecting the substitute substance is thus integrated into the sensor 44 itself. The refrigerant, preferably in the form of the fluorinated hydrocarbon, can also be detected by means of the sensor 44.

[0080] It is particularly easy if there are already 10 sensors in the refrigerant circuit, or if sensors are planned for installation, such as the one in Fig. 1. The pressure sensor 26 and the temperature sensor 28 shown as examples are used to record measured quantities and to make these measured quantities available to the control unit 30 for evaluation.

[0081] In all those relating to Fig. 1, Fig. 2 and Fig. In the 3 described constellations, the control device 30 ensures that the compressor 14 does not start or is not put into operation if the substitute substance is in the refrigerant circuit 10 or the refrigerant circuit 10 is filled with the substitute substance.

[0082] Furthermore, the control unit 30 can be in Fig. 1. Control the fan 48 of the refrigerant circuit 10 shown schematically. If the refrigerant circuit 10 (as shown in Fig. 5 shown) is arranged in the motor vehicle 12, the fan 48 can be provided to supply coolable air into a passenger compartment 50 of the motor vehicle 12 by means of the evaporator 20 (compare Fig.5) to introduce. Thus, even if the refrigerant circuit 10 is filled with the substitute substance not suitable for the operation of the refrigerant circuit 10 and therefore the compressor 14 is not running, ventilation of the passenger compartment 50 can still be advantageously ensured by operating at least one fan 48.

[0083] If the substitute refrigerant is removed or drained from refrigerant circuit 10 and the refrigerant for which refrigerant circuit 10 is designed is added, then refrigerant circuit 10 can be put into operation in the motor vehicle 12, for example to provide air conditioning and / or heating for the passenger compartment 50. However, as long as the substitute refrigerant is present in refrigerant circuit 10, the refrigerant circuit 10 is safely deactivated. This is ensured by the control unit 30, which prevents the compressor 14 from operating.

[0084] Overall, the examples show how a refrigerant substitute in the form of the replacement substance can be provided for the safe deactivation of the refrigerant circuit 10 by sensor control.

Claims

[1] Refrigerant circuit (10) for a motor vehicle (12), wherein the refrigerant circuit (10) is designed for operation with a refrigerant in the form of at least one fluorinated hydrocarbon, with a compressor (14) for conveying the refrigerant to a heat exchanger (16) of the refrigerant circuit (10), and with a control device (30) for controlling the compressor (14), wherein the refrigerant circuit (10) is filled with a substitute substance other than fluorinated hydrocarbons, wherein the refrigerant circuit (10) has at least one sensor (26, 28, 42, 44) by means of which the substitute substance can be distinguished from the at least one fluorinated hydrocarbon, characterized byin that the control device (30) is designed to prevent the compressor (14) from being started up if the presence of the substitute substance in the refrigerant circuit (10) can be detected by means of the at least one sensor (26, 28, 42, 44), wherein the control device (30) is designed to cause at least one fan (48) of the refrigerant circuit (10) to be started up if the operation of the compressor (14) is prevented, and wherein the at least one fan (48) is designed to convey air which can be temperature-controlled during operation of the refrigerant circuit (10). [2] Refrigerant circuit (10) according to claim 1, characterized by that the substitute substance, in particular having at least one gas phase, is under a pressure in the refrigerant circuit (10) which is greater than a pressure in an environment (24) of the refrigerant circuit (10). [3] Refrigerant circuit (10) according to one of the preceding claims, characterized bythat the at least one sensor (42) is associated with an analysis device (40) of the refrigerant circuit (10), wherein the analysis device (40) is designed to identify the substitute substance. [4] Refrigerant circuit (10) according to one of the preceding claims, characterized by in that the at least one sensor (44) comprises an evaluation device (46) which is designed to infer the presence of the substitute substance in the refrigerant circuit (10) by evaluating at least one measured variable which can be detected by means of the sensor (44), wherein the evaluation device (46) is designed to communicate with the control device (30). [5] Refrigerant circuit (10) according to one of the preceding claims, characterized byin that the at least one sensor (26, 28, 42, 44) is designed to communicate to the control device (30) at least one measured variable that can be detected by means of the sensor (26, 28, 42, 44), wherein the control device (30) is designed to infer the presence of the substitute substance in the refrigerant circuit (10) by evaluating the at least one measured variable. [6] Refrigerant circuit (10) according to one of the preceding claims, characterized by that the at least one sensor (26, 28) is designed as a pressure sensor and / or as a temperature sensor. [7] Refrigerant circuit (10) according to one of the preceding claims, characterized by that the at least one sensor (26, 28, 42, 44) is designed to detect at least one measured variable by means of which the refrigerant in the form of the at least one fluorinated hydrocarbon can be identified. [8] Motor vehicle (12) with a refrigerant circuit (10) according to one of the preceding claims. [9] Method for operating a refrigerant circuit (10) for a motor vehicle (12), wherein the refrigerant circuit (10) is designed for operation with a refrigerant in the form of at least one fluorinated hydrocarbon, wherein a compressor (14) of the refrigerant circuit (10) is designed to convey the refrigerant to a heat exchanger (16) of the refrigerant circuit (10), and wherein a control device (30) of the refrigerant circuit (10) controls the compressor (14), wherein the refrigerant circuit (10) is filled with a substitute substance other than fluorinated hydrocarbons, wherein the refrigerant circuit (10) has at least one sensor (26, 28, 42, 44) by means of which the substitute substance can be distinguished from the at least one fluorinated hydrocarbon, characterized by , that the control device (30) prevents the compressor (14) from being started up if the presence of the substitute substance in the refrigerant circuit (10) is detected by means of the at least one sensor (26, 28, 42, 44), wherein the control device (30) causes at least one fan (48) of the refrigerant circuit (10) to be started up if the operation of the compressor (14) is prevented, wherein the at least one fan (48) is designed to convey air which can be temperature-controlled during operation of the refrigerant circuit (10).

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