Device for an air conditioning system of a motor vehicle and method for operating the device

Abstract

Device (1a, 1b, 1c) for an air conditioning system of a motor vehicle, comprising at least one first refrigerant circuit (2a, 2c) and a second refrigerant circuit (3), which are thermally connected to each other via a first refrigerant-to-refrigerant heat exchanger (18) for heat transfer from a refrigerant of the second refrigerant circuit (3) to a refrigerant of the at least one first refrigerant circuit (2a, 2c) and a second refrigerant-to-refrigerant heat exchanger (23) for heat transfer from the refrigerant of the at least one first refrigerant circuit (2a, 2c) to the refrigerant of the second refrigerant circuit (3), wherein - the at least one first refrigerant circuit (2a, 2c) is designed in a flow direction of the refrigerant with a compressor (4), the second refrigerant-to-refrigerant heat exchanger (23), the first refrigerant-to-refrigerant heat exchanger (18) and a heat exchanger (20) that can be operated as an evaporator, wherein a first expansion element (17) is arranged upstream of the first refrigerant-to-refrigerant heat exchanger (18) and a second expansion element (19) is arranged upstream of the heat exchanger (20), - the second refrigerant circuit (3) is designed in a flow direction of the refrigerant with a compressor (25), the first refrigerant-to-refrigerant heat exchanger (18), at least one expansion element (33), a refrigerant-to-air heat exchanger (35) for heat transfer between the refrigerant and a supply air for a passenger compartment and the second refrigerant-to-refrigerant heat exchanger (23), wherein the second refrigerant-to-refrigerant heat exchanger (23) is arranged with an upstream expansion element (34) in the flow direction of the refrigerant after the refrigerant-to-air heat exchanger (35).

Description

[0001] The invention relates to a device for an air conditioning system of a motor vehicle with at least a first and a second refrigerant circuit. The refrigerant circuits are thermally connected to each other via a first refrigerant-to-refrigerant heat exchanger for heat transfer from the refrigerant of the second refrigerant circuit to the refrigerant of the first refrigerant circuit, and a second refrigerant-to-refrigerant heat exchanger for heat transfer from the refrigerant of the first refrigerant circuit to the refrigerant of the second refrigerant circuit. The invention also relates to methods for operating the device for an air conditioning system of a motor vehicle.

[0002] Passenger vehicles with a large passenger compartment, such as sports cars, utility vehicles, SUVs, raised vehicles, high-roof station wagons, minibuses (VANs), or luxury vehicles, all have high heating and cooling requirements and are equipped with air conditioning systems and refrigerant circuits with at least two evaporators to, for example, climate control different areas of the passenger compartment separately. The passenger compartment is typically divided into a front and a rear section. The terms "front section" and "rear section" refer to the direction of travel of the vehicle.

[0003] A first airflow is conditioned as it passes over a first evaporator, the so-called front evaporator, and directed into the front of the passenger compartment to create a comfortable climate for both the driver and front passenger. A second airflow is conditioned as it passes over a second evaporator, the so-called rear evaporator, and directed into the rear of the passenger compartment to create a comfortable climate for the occupants of the second and, if applicable, the third row of seats.

[0004] The front evaporator and the rear evaporator are arranged in separate air conditioning units. Each air conditioning unit can independently provide a desired air volume flow with a required air temperature and a predetermined airflow direction.

[0005] To heat the intake air for the passenger compartment, conventional motor vehicles utilize, for example, the waste heat from the engine. This waste heat is transported to the air conditioning system via the coolant circulated in the engine's coolant circuit and transferred there to the air flowing into the passenger compartment via the heating heat exchanger. Known systems with coolant-to-air heat exchangers, which derive their heating power from the coolant circuit of an efficient internal combustion engine, no longer reach the level required for comfortable heating of the passenger compartment at low ambient temperatures in order to meet the total heating demand of the passenger compartment. A similar situation applies to systems in hybrid vehicles, i.e., vehicles with both electric and internal combustion engine propulsion.

[0006] If, for example, the total heating demand of the passenger compartment and the drive components cannot be met by the heat from the engine coolant circuit, supplementary heating measures such as electric resistance heaters, abbreviated as PTC resistors (Positive Temperature Coefficient Thermistors), or fuel heaters are required. The same applies to systems in fuel cell vehicles.

[0007] A more efficient way to absorb heat, especially for heating the air in the passenger compartment or preheating the drive components, is a heat pump using air as the heat source, in which the refrigerant circuit serves both as the sole heating source and as a supplementary heating measure. However, a system with heat pump functionality requires a large amount of installation space.

[0008] Furthermore, conventional hybrid and purely electric vehicles, often referred to as electric vehicles, typically have higher heating and cooling requirements than purely internal combustion engine vehicles due to their additional components, particularly within the electric powertrain, such as an internal battery charger, a transformer, an inverter, the traction battery itself, and the electric drive motor. To comply with the permissible temperature limits of the high-voltage battery, which are usually between 20°C and 35°C, either an additional refrigerant-to-coolant heat exchanger, also known as a chiller, or a directly refrigerant-cooled heat exchanger designed as a battery cooler must be provided.Thus, conventional motor vehicles with a purely electric drive or a hybrid drive can, in addition to the refrigerant circuit of the actual air conditioning system for conditioning the supply air for the passenger compartment, also be equipped with a coolant circuit in which coolant circulates to remove the heat emitted by the drive components or to preheat the drive components.

[0009] For example, a vehicle with an electric-combustion engine hybrid drive and a large passenger compartment consequently has a comparatively high cooling requirement. A conventional air conditioning system with a refrigerant circuit and a single compressor is not capable of providing the required refrigerant mass flow rate for cooling the passenger compartment and the electrical components.

[0010] Various air conditioning systems are known for providing comparatively high cooling capacities. On the one hand, at least two compressors are operated in parallel within a conventional refrigerant circuit, thus doubling or multiplying the refrigerant mass flow. On the other hand, at least two independent refrigerant circuits are used, with each additional circuit having additional components.

[0011] US 7 228 707 B2 and US 2013 / 0145781 A1 each describe a refrigerant circuit with compressors arranged in parallel. The compressors, connected in parallel, compress the refrigerant into a common pressure line, which carries the refrigerant to a heat exchanger operating as a condenser.

[0012] The refrigerant circuit known from US 7 228 707 B2, in economizer configuration, also features a multitude of heat exchangers operating as evaporators, which serve to condition different environments. Each evaporator is connected to a compressor.

[0013] US patent 2013 / 0145781 A1 discloses a refrigerant circuit with two compressors, wherein the first compressor is speed-controlled and the second compressor is designed to operate at a fixed speed.

[0014] German patent application DE 10 2017 109 311 A1 discloses a device for an air conditioning system of a motor vehicle with a first and a second refrigerant circuit. The first refrigerant circuit, in the direction of refrigerant flow, comprises a compressor, a first refrigerant-to-refrigerant heat exchanger operating as a condenser for the refrigerant, an expansion device, and a first refrigerant-to-coolant heat exchanger of a coolant circuit operating as an evaporator. The second refrigerant circuit, in the direction of refrigerant flow, comprises a compressor, a second refrigerant-to-coolant heat exchanger of a coolant circuit operating as a condenser / gas cooler, an expansion device, and the first refrigerant-to-refrigerant heat exchanger operating as an evaporator for the refrigerant of the second refrigerant circuit.

[0015] DE 102 24 754 A1 discloses an air conditioning system suitable for stationary operation, in particular a refrigerant circuit, for the interior of a motor vehicle with a compressor, a condenser, an expansion device, an evaporator and a cold storage unit which can be discharged when the air conditioning system is stationary.

[0016] In refrigerant circuits known from the prior art, the individual components, such as a heat exchanger operated as a condenser / gas cooler, the refrigerant lines as connecting lines between the components, possibly an internal heat exchanger and the valves, must be dimensioned very large in accordance with the high maximum mass flow of the refrigerant.

[0017] In vehicles with an electric hybrid drive as well as in vehicles with a purely internal combustion engine drive, an additional coolant-to-air heat exchanger is already integrated into the coolant circuit, meaning there is no installation space in the front of the vehicle for a larger condenser / gas cooler. Furthermore, large-diameter refrigerant lines, or even oversized for many operating points of the system, would have to be installed.

[0018] Air conditioning systems with independently operated refrigerant circuits, each with separately designed components, always require at least one additional condenser / gas cooler. Since the additional coolant-to-air heat exchanger is integrated into the coolant circuit in vehicles with an electric hybrid drive or a purely internal combustion engine drive, the available installation space in the front of the vehicle is so limited that integrating another condenser / gas cooler is virtually impossible.

[0019] In various air conditioning systems known from the prior art, with a single refrigerant circuit and parallel-operated compressors or with multiple refrigerant circuits, the rear evaporator and, if applicable, additional evaporators must each be connected to the condenser / gas cooler located at the front of the vehicle via refrigerant lines. These refrigerant lines must be routed throughout the entire vehicle, occupying valuable installation space. The refrigerant lines must be designed for high pressures and require special fittings, which is very expensive. Furthermore, long refrigerant lines also cause significant pressure losses in the refrigerant circuit, leading to reduced cooling capacity or increased compressor load.

[0020] The object of the invention is to provide a device with sufficient cooling and heating capacities for motor vehicles with high cooling requirements and potentially also high heating requirements, for example, for motor vehicles with an electric or a combined electric and combustion engine drive. Manufacturing costs, maintenance costs, operating costs, and the required installation space should be minimal. The system should be operable with maximum efficiency.

[0021] Furthermore, an object of the invention is to provide methods for operating the device for an air conditioning system into which several heat sources or heat sinks at different or the same temperature levels can be integrated.

[0022] The problem is solved by the subject matter with the features of the independent patent claims. Further developments are specified in the dependent patent claims.

[0023] The problem is solved by a device for an air conditioning system of a motor vehicle with high cooling and heating requirements. The device comprises at least one first refrigerant circuit and one second refrigerant circuit, which are thermally connected via a first refrigerant-to-refrigerant heat exchanger for heat transfer from a refrigerant of the second refrigerant circuit to a refrigerant of the first refrigerant circuit, and a second refrigerant-to-refrigerant heat exchanger for heat transfer from the refrigerant of the first refrigerant circuit to the refrigerant of the second refrigerant circuit. The first refrigerant circuit and the second refrigerant circuit are preferably arranged in a cascade configuration.

[0024] According to the invention, the at least one first refrigerant circuit is configured in one flow direction of the refrigerant with a compressor, a second refrigerant-to-refrigerant heat exchanger (which can be operated as a condenser / gas cooler, particularly for the refrigerant of the at least one first refrigerant circuit), a first refrigerant-to-refrigerant heat exchanger (which can be operated as an evaporator, particularly for the refrigerant of the at least one first refrigerant circuit), and a further heat exchanger (which can be operated as an evaporator). A first expansion element is arranged upstream of the first refrigerant-to-refrigerant heat exchanger in the at least one first refrigerant circuit, and a second expansion element is arranged upstream of the further heat exchanger.

[0025] The second refrigerant circuit is designed in a flow direction of the refrigerant with a compressor, the first refrigerant-to-refrigerant heat exchanger which can be operated as a condenser / gas cooler, in particular for the refrigerant of the second refrigerant circuit, at least one expansion device and the second refrigerant-to-refrigerant heat exchanger which can be operated as an evaporator, in particular for the refrigerant of the second refrigerant circuit.

[0026] The at least one first refrigerant circuit advantageously has an accumulator which is arranged in the direction of flow of the refrigerant upstream of an inlet of the compressor and thus on the low-pressure side.

[0027] When the refrigerant is liquefied during subcritical operation of the respective refrigerant circuit, such as with refrigerant R134a or under certain ambient conditions with carbon dioxide, the heat exchanger is called a condenser. Part of the heat transfer takes place at a constant temperature. During supercritical operation, or when heat is released supercritically in the heat exchanger, the temperature of the refrigerant decreases steadily. In this case, the heat exchanger is also called a gas cooler. Supercritical operation can occur under certain ambient conditions or operating modes of the refrigerant circuit, for example, with carbon dioxide as the refrigerant.

[0028] According to a further development of the invention, the first refrigerant circuit has a heat exchanger which can be operated as a condenser / gas cooler, in particular for the refrigerant of the first refrigerant circuit, and which is arranged within a first flow path in the flow direction of the refrigerant upstream of the second refrigerant-refrigerant heat exchanger.

[0029] According to a first alternative embodiment of the invention, the heat exchanger is designed as a refrigerant-air heat exchanger for heating supply air for a passenger compartment.

[0030] According to a second alternative embodiment of the invention, the heat exchanger is designed as a refrigerant-coolant heat exchanger of a coolant circuit for heat transfer from the refrigerant of the first refrigerant circuit to the coolant. The coolant circuit in which the refrigerant-coolant heat exchanger is arranged advantageously includes a heating heat exchanger for heating supply air for a passenger compartment. The coolant circuit can also be designed with a coolant-air heat exchanger for heat transfer from the coolant to ambient air, wherein the heating heat exchanger and the coolant-air heat exchanger for heat transfer from the coolant to the ambient air are preferably designed to allow parallel flow of coolant.

[0031] According to an advantageous embodiment of the invention, the first refrigerant circuit comprises a valve arrangement with a first branch point and a first outlet. Between the first branch point and the first outlet extend the first flow path and a flow path with a refrigerant-to-air heat exchanger, which can be operated as a condenser / gas cooler, particularly for the refrigerant of the first refrigerant circuit, for heat transfer from the refrigerant of the first refrigerant circuit to the ambient air.

[0032] A further preferred embodiment of the invention consists in the first refrigerant-to-refrigerant heat exchanger and the first expansion element arranged upstream of the first refrigerant-to-refrigerant heat exchanger in the flow direction of the refrigerant of the first refrigerant circuit being located within a second flow path, as well as the further heat exchanger, which can be operated as an evaporator, and the second expansion element, which can be operated as an evaporator, being located upstream of the further heat exchanger, which can be operated as an evaporator, being located within a third flow path. The flow paths extend from a second branch point to a second outlet point of the first refrigerant circuit and are arranged parallel to each other, so that the flow paths and the heat exchangers can be permeated by refrigerant flow in parallel.

[0033] The further heat exchanger of the first refrigerant circuit, which can be operated as an evaporator, is advantageously designed as a refrigerant-coolant heat exchanger of a coolant circuit for temperature control of components of a motor vehicle powertrain.

[0034] According to a further development of the invention, the second refrigerant circuit is designed with a refrigerant-to-air heat exchanger, which can be operated as an evaporator, particularly for the refrigerant of the second refrigerant circuit, for heat transfer between the refrigerant of the second refrigerant circuit and the supply air for a passenger compartment. A first expansion element of the second refrigerant circuit is arranged upstream of the refrigerant-to-air heat exchanger in the direction of refrigerant flow.

[0035] According to the invention, the second refrigerant circuit is designed with a refrigerant-to-air heat exchanger, which can be operated as an evaporator or condenser / gas cooler, particularly for the refrigerant of the second refrigerant circuit, for heat transfer between the refrigerant of the second refrigerant circuit and the supply air for the passenger compartment. Advantageously, a second expansion element of the second refrigerant circuit is arranged upstream of the refrigerant-to-air heat exchanger in the direction of refrigerant flow.

[0036] The second refrigerant-to-refrigerant heat exchanger of the device is conceptually arranged with an upstream expansion element in the flow direction of the refrigerant of the second refrigerant circuit downstream of the refrigerant-to-air heat exchanger, which can be operated as an evaporator or condenser / gas cooler.

[0037] The refrigerant-to-air heat exchanger, which can be operated as an evaporator for heat transfer between the refrigerant of the second refrigerant circuit and the supply air for the passenger compartment, and the first expansion element arranged upstream of the refrigerant-to-air heat exchanger in the flow direction of the refrigerant of the second refrigerant circuit, are preferably arranged within a first flow path, while the refrigerant-to-air heat exchanger, which can be operated as an evaporator or condenser / gas cooler,The second expansion element, located upstream of the refrigerant-to-air heat exchanger in the flow direction of the refrigerant in the second refrigerant circuit, as well as the second refrigerant-to-refrigerant heat exchanger and the third expansion element, located upstream of the second refrigerant-to-refrigerant heat exchanger in the flow direction of the refrigerant in the second refrigerant circuit, are formed within a second flow path. The flow paths extend from a branch point to a discharge point of the second refrigerant circuit and are arranged parallel to each other, so that the refrigerant can flow through the flow paths and the refrigerant-to-air heat exchangers in parallel.

[0038] The problem is also solved by methods according to the invention for operating the device for an air conditioning system of a motor vehicle. The air conditioning system can be operated, in particular for heating, cooling and / or dehumidifying the supply air to the passenger compartment of the motor vehicle, in a refrigeration mode, in a heat pump mode and in a reheating mode.

[0039] According to the invention, in a first method, during operation in a refrigeration mode of the air conditioning system, cooling capacity is provided at a first medium temperature level, wherein heat is transferred from coolant circulating in a coolant circuit to refrigerant of a first refrigerant circuit in a refrigerant-coolant heat exchanger. Furthermore, cooling capacity is provided at a low temperature level, wherein heat is transferred from supply air for the passenger compartment to refrigerant of a second refrigerant circuit in at least one refrigerant-air heat exchanger.

[0040] In a further method according to the invention, during operation in a post-heating mode of the air conditioning system, cooling capacity is provided at a low temperature level, wherein heat is transferred from a supply air for the passenger compartment to a refrigerant of a second refrigerant circuit in a refrigerant-to-air heat exchanger. In addition, heating capacity, in particular post-heating capacity, is provided at a high temperature level, wherein heat is transferred in a refrigerant-to-air heat exchanger from a refrigerant of a first refrigerant circuit directly to supply air for the passenger compartment, or in a refrigerant-to-coolant heat exchanger, heat is transferred to a coolant circulating in a coolant circuit, and in a heating heat exchanger, from the coolant to supply air for the passenger compartment.

[0041] According to a further development of the invention, cooling capacity is also provided at a first intermediate temperature level, wherein heat is transferred in a refrigerant-coolant heat exchanger from the coolant circulating in a coolant circuit to the refrigerant of the first refrigerant circuit. The coolant is advantageously used as a heat source for reheating the supply air for the passenger compartment.

[0042] In a further method according to the invention, when the air conditioning system is operating in heat pump mode, heating capacity is provided at a high temperature level. This is achieved by transferring heat from a refrigerant of a first refrigerant circuit directly to the supply air for the passenger compartment in a refrigerant-to-air heat exchanger, or by transferring heat from the refrigerant circulating in a coolant circuit to a coolant circulating in a refrigerant circuit, and then from the coolant to the supply air for the passenger compartment in a heating heat exchanger. Additionally, cooling capacity is provided at a first medium temperature level. This is achieved by transferring heat from a coolant circulating in a coolant circuit to the refrigerant of the first refrigerant circuit in a refrigerant-to-coolant heat exchanger. The coolant is advantageously used as a heat source for heating the supply air for the passenger compartment.

[0043] According to an advantageous embodiment of the invention, heating power is also provided at a second intermediate temperature level, wherein heat is transferred from a refrigerant of a second refrigerant circuit to the supply air for the passenger compartment in a refrigerant-to-air heat exchanger, so that the supply air for the passenger compartment is preheated as it flows through the refrigerant-to-air heat exchanger of the first refrigerant circuit or the heating heat exchanger and is heated to a final temperature as it flows through the refrigerant-to-air heat exchanger of the second refrigerant circuit. Thus, the supply air for the passenger compartment is heated in two steps by means of two heat exchangers.

[0044] According to a further development of the invention, the heat to be dissipated by electrical components of a motor vehicle's powertrain is transferred to the coolant circulating in the coolant circuit. Subsequently, in the refrigerant-coolant heat exchanger, the heat is transferred from the coolant to the refrigerant of the first refrigerant circuit at the first intermediate temperature level.

[0045] This allows electrical components of a powertrain, especially of a motor vehicle with an electric or a combined electric and combustion engine drive, such as a high-voltage battery and an inverter, to be supplied with coolant at a medium temperature level, thus minimizing the consumption of electrical energy, such as the consumption of the compressors of the refrigerant circuits, and increasing the efficiency of the overall system.

[0046] A further advantage of the invention is that in a first refrigerant-to-refrigerant heat exchanger, heat is transferred from the refrigerant of a second refrigerant circuit to the refrigerant of the first refrigerant circuit, and that in a second refrigerant-to-refrigerant heat exchanger, heat is transferred from the refrigerant of the first refrigerant circuit to the refrigerant of the second refrigerant circuit. In the first refrigerant-to-refrigerant heat exchanger, the refrigerant of the first refrigerant circuit is evaporated or superheated, and the refrigerant of the second refrigerant circuit is condensed / cooled or subcooled, while in the second refrigerant-to-refrigerant heat exchanger, the refrigerant of the first refrigerant circuit is deheated and condensed / cooled or subcooled, and the refrigerant of the second refrigerant circuit is evaporated and / or superheated.

[0047] The device and methods according to the invention offer several advantages: - Providing high thermal outputs, in particular cooling outputs or heating outputs at different, specifically three different temperature levels, by means of two-stage compression, in particular - High-performance heating operation by heating the supply air for the passenger compartment using two heat exchangers in two process steps, - High system performance with the device at maximum service life, especially since the operation of the compressors is adapted to different pressure levels, thus ensuring favorable compression ratios per compression stage even at high power levels, - Distributing the system load among the compressors in such a way that each compressor is operated in an optimal operating range of the respective compressor map, i.e. in an efficient map range with high isentropic or overall efficiency, - maximum efficiency of the system with the device, including the use of an indirect internal heat exchanger or by providing a medium temperature level for cooling, for example a high-voltage battery and / or electrical components of the powertrain, - Independent filling of the refrigerant circuits with any refrigerant, as there is no exchange of refrigerants between the refrigerant circuits; both a refrigerant that can be operated in the subcritical range, such as R134a, R1234yf, and a refrigerant that can be operated in the supercritical range, such as R744, can be used. - small refrigerant fill quantities, - no oil traps in the refrigerant circuits compared to dual evaporator direct systems, - minimal installation space as well as minimal operating costs, manufacturing costs and maintenance costs.

[0048] Further details, features, and advantages of embodiments of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. These show: Fig. 1: a device for an air conditioning system of a motor vehicle with a first and a second refrigerant circuit, which are thermally coupled to each other via two refrigerant-to-refrigerant heat exchangers, Fig. 2a: the device according to Fig. 1 when operating in refrigeration system mode, Fig. 2b: the device according to Fig. 1 during operation in refrigeration system mode and with cooling of drive train components, Fig. 2c: the device according to Fig. 1. During operation with cooling of drive train components, Fig. 3a: the device according to Fig. 1 when operating in post-heating mode, Fig. 3b: the device according to Fig. 1 during operation in post-heating mode and with cooling of drive train components, Fig. 4a: the device according to Fig. 1 during operation of the first refrigerant circuit in a first heat pump mode and with cooling of drive train components, Fig. 4b: the device according to Fig. 1 when operating in a second heat pump mode and with cooling of drive train components, Fig. 4c: the device according to Fig. 1 when operating in a third heat pump mode and with cooling of drive train components, Fig. 5: a device for an air conditioning system according to Fig. 1 with a coolant circuit with a heat exchanger as well as Fig. 6: a device for an air conditioning system according to Fig. 5 with a coolant-to-air heat exchanger for transferring heat to ambient air.

[0049] In Fig. Figure 1 shows a device 1a for an air conditioning system of a motor vehicle, comprising a first refrigerant circuit 2a and a second refrigerant circuit 3. The refrigerant circuits 2a and 3 are thermally coupled to each other via two refrigerant-to-refrigerant heat exchangers 18 and 23 and arranged in a cascade configuration.

[0050] The first refrigerant circuit 2a, also referred to as the upper stage or upper refrigerant circuit of the cascade system, comprises, in the direction of refrigerant flow, a compressor 4, a valve arrangement 5, a first refrigerant-to-air heat exchanger 11 which can be operated as a condenser / gas cooler, a first expansion element 17 with the subsequent first refrigerant-to-refrigerant heat exchanger 18 which can be operated as an evaporator for the refrigerant of the first refrigerant circuit 2a, and an accumulator 21.

[0051] The accumulator 21, located upstream of the compressor 4 in the direction of refrigerant flow and thus on the low-pressure side, serves to separate and collect liquid refrigerant. The compressor 4 draws gaseous refrigerant from the accumulator 21. The first refrigerant circuit 2a is closed.

[0052] The valve assembly 5 comprises a first shut-off valve 6 and a second shut-off valve 7, as well as a first branch point 8. The first shut-off valve 6 is located between the branch point 8 of the valve assembly 5 and the refrigerant-to-air heat exchanger 11, while the second shut-off valve 7 is formed within a first flow path 9 of the first refrigerant circuit 2a. The first flow path 9 extends from the branch point 8 of the valve assembly 5 to a first outlet 10, which is located between the refrigerant-to-air heat exchanger 11 and the first expansion device 17. Downstream of the shut-off valve 7, the first flow path 9 includes a second refrigerant-to-air heat exchanger 22a, which can be operated as a condenser / gas cooler, and a second refrigerant-to-refrigerant heat exchanger 23. The second refrigerant-to-refrigerant heat exchanger is operated as an indirect internal heat exchanger.

[0053] According to an alternative embodiment, not shown, the valve arrangement is designed as a three-way valve.

[0054] Furthermore, the first refrigerant circuit 2a has two check valves 12 and 24. The first check valve 12 is located between the first refrigerant-to-air heat exchanger 11 and the first outlet 10 of the first flow path 9 to prevent refrigerant flowing through the first flow path 9 from flowing back into the refrigerant-to-air heat exchanger 11 when it is not carrying refrigerant. The second check valve 24 is located within the first flow path 9, in the direction of refrigerant flow immediately upstream of the first outlet 10 to prevent refrigerant flowing through the refrigerant-to-air heat exchanger 11 from flowing back into the first flow path 9 when it is not carrying refrigerant.

[0055] The first refrigerant circuit 2a is also equipped with a further heat exchanger, in particular a refrigerant-coolant heat exchanger 20 of a coolant circuit for temperature control of components of a motor vehicle's powertrain to a medium temperature level, also referred to as a chiller. A second expansion element 19 of the first refrigerant circuit 2a is located upstream of the refrigerant-coolant heat exchanger 20. The refrigerant-coolant heat exchanger 20 is predominantly operated in such a way as to provide coolant at a temperature level below the ambient air temperature or waste heat from the preferably electrical components of the motor vehicle's powertrain for heating the supply air to the passenger compartment. The coolant, in particular the components of the powertrain, then serve as a heat source for heating the supply air.

[0056] The first refrigerant-to-refrigerant heat exchanger 18 and the associated first expansion element 17 of the first refrigerant circuit 2a are located within a second flow path 13, while the refrigerant-to-coolant heat exchanger 20 and the associated second expansion element 19 of the first refrigerant circuit 2a are located within a third flow path 14. The flow paths 13 and 14 each extend from a second branch point 15 to a second outlet point 16 and thus run parallel, so that the first refrigerant-to-refrigerant heat exchanger 18 and the refrigerant-to-coolant heat exchanger 20 are arranged parallel to each other and can be supplied with refrigerant in parallel.The second branch point 15 is arranged in the direction of flow of the refrigerant after the first outlet point 10 of the first flow path 9, while the second outlet point 16 is arranged in the direction of flow of the refrigerant in front of the accumulator 21 and thus in front of the compressor 4.

[0057] The expansion elements 17, 19 are preferably each designed as an expansion valve.

[0058] The second refrigerant circuit 3, also referred to as the lower stage or lower refrigerant circuit of the cascade system, comprises, in the direction of refrigerant flow, a compressor 25, the first refrigerant-to-refrigerant heat exchanger 18 (which can be operated as a condenser / gas cooler for the refrigerant of the second refrigerant circuit 3), and a first expansion element 30, followed by the third refrigerant-to-air heat exchanger 31 (which can be operated as an evaporator for the refrigerant of the second refrigerant circuit 3). The compressor 25 draws gaseous refrigerant from the third refrigerant-to-air heat exchanger 31. The first refrigerant circuit 3 is closed.

[0059] After exiting the first refrigerant-to-refrigerant heat exchanger 18, which can be operated as a condenser, and thus on the high-pressure side, a collector or liquid separator (not shown) can be arranged, from which liquid refrigerant is directed to expansion devices.

[0060] The second refrigerant circuit 3 is also equipped with a fourth refrigerant-air heat exchanger 35, to which a second expansion element 33 of the second refrigerant circuit 3 is arranged upstream and a third expansion element 34 of the second refrigerant circuit 3 is arranged downstream.

[0061] The third refrigerant-to-air heat exchanger 31 and the associated first expansion element 30 of the second refrigerant circuit 3 are located within a first flow path 26 of the second refrigerant circuit 3, while the fourth refrigerant-to-air heat exchanger 35 and the associated expansion elements 33, 34 are located within a second flow path 27. The flow paths 26, 27 each extend from a branch point 28 to a discharge point 29 and thus run parallel, so that the refrigerant-to-air heat exchangers 31, 35 are arranged parallel to each other and can be supplied with refrigerant in parallel. The branch point 28 is arranged between the first refrigerant-to-refrigerant heat exchanger 18, which can be operated as a condenser / gas cooler, and the first expansion element 30 of the second refrigerant circuit 3, while the outlet point 29 is arranged in the direction of refrigerant flow upstream of the compressor 25.The expansion elements 33, 34, arranged in the direction of refrigerant flow immediately upstream and downstream of the fourth refrigerant-to-air heat exchanger 35, enable the setting of an average pressure level and, consequently, an average temperature level of the refrigerant as it flows through the refrigerant-to-air heat exchanger 35, which can be operated as a front evaporator or condenser / gas cooler. The pressure and temperature levels of the refrigerant as it flows through the refrigerant-to-air heat exchangers 31, 35 can be set independently of one another. The expansion elements 30, 33, 34 are preferably each designed as an expansion valve.

[0062] Within the second flow path 27 of the second refrigerant circuit 3, the second refrigerant-to-refrigerant heat exchanger 23 is also arranged, which is formed in the direction of refrigerant flow after the third expansion element 34 of the second refrigerant circuit 3 and before the outlet 29.

[0063] The device 1 comprises two refrigerant circuits, 2a and 3, which are materially separate from each other and can be operated at different pressure and temperature levels. The first refrigerant circuit 2a, also referred to as the upper-stage refrigerant circuit of the cascade system, operates at a significantly higher pressure than the second refrigerant circuit 3, also referred to as the lower-stage refrigerant circuit. Due to the material separation of the refrigerant circuits 2a and 3, no refrigerant is exchanged between them.

[0064] Due to the physical separation of refrigerant circuits 2a and 3, both circuits can be filled independently with any refrigerant. Refrigerant circuits 2a and 3 and their operating modes are suitable for any refrigerant that undergoes a phase transition from liquid to gaseous on the low-pressure side. On the high-pressure side, the medium releases the absorbed heat to a heat sink through condensation / gas cooling and subcooling. Suitable refrigerants include natural substances such as R744, R717, and similar; flammable substances such as R290, R600, R600a, and similar; chemical substances such as R134a, R152a, and R1234yf; and various refrigerant mixtures.However, in order to take advantage of the benefits of different refrigerants when operating at different pressure levels, the first refrigerant circuit 2a is preferably filled with one of the refrigerants R134a or R1234yf, each with subcritical operation, and the second refrigerant circuit is preferably filled with the refrigerant R744.

[0065] The refrigerant-to-refrigerant heat exchangers 18, 23 serve to thermally connect the refrigerant circuits 2a, 3. In this process, heat is transferred between the refrigerants of the refrigerant circuits 2a, 3.

[0066] The first refrigerant-to-refrigerant heat exchanger 18 is located within the first refrigerant circuit 2a on the low-pressure side within the second flow path 13 after the expansion device 17, and within the second refrigerant circuit 3 on the high-pressure side between the compressor 25 and the branch point 28 or at least one of the expansion devices 30, 33, thus connecting the low-pressure side of the first refrigerant circuit 2a with the high-pressure side of the second refrigerant circuit 3. In the first refrigerant-to-refrigerant heat exchanger 18, the heat of heat dissipation and the heat of condensation of the refrigerant of the second refrigerant circuit 3 can be transferred to the refrigerant of the first refrigerant circuit 2a, whereby the refrigerant of the second refrigerant circuit 3 can be liquefied and the refrigerant of the first refrigerant circuit 2a can be evaporated.

[0067] The second refrigerant-to-refrigerant heat exchanger 23 is also designed similarly to an internal heat exchanger of a refrigerant circuit, which is located on the high-pressure side within the first refrigerant circuit 2a, in the first flow path 9 in the direction of refrigerant flow after the second refrigerant-to-air heat exchanger 22a, which can be operated as a condenser / gas cooler, and on the low-pressure side within the second refrigerant circuit 3, in the second flow path 27 in the direction of refrigerant flow after the fourth refrigerant-to-air heat exchanger 35 and the third expansion element 34 of the second refrigerant circuit 3 and thus before the compressor 25.

[0068] The second refrigerant-to-refrigerant heat exchanger 23, which consequently connects a suction line of the second refrigerant circuit 3 with a high-pressure liquid line of the first refrigerant circuit 2a, serves, similar to an internal internal heat exchanger, for heat transfer between the refrigerant of the first refrigerant circuit 2a at high pressure and the refrigerant of the second refrigerant circuit 3 at low pressure, and is also referred to as an indirect internal heat exchanger. On the one hand, the refrigerant of the first refrigerant circuit 2a flowing out of the second refrigerant-to-air heat exchanger 22a, which can be operated as a condenser / gas cooler, can be liquefied or cooled or subcooled, depending on the operating mode of the device 1a and the state of the refrigerant. On the other hand, the refrigerant of the second refrigerant circuit 3 exiting the fourth refrigerant-to-air heat exchanger 35 is superheated as suction gas upstream of the compressor 25.

[0069] In addition to protecting the compressor 25 from liquid slugs, the operation of the second refrigerant-to-refrigerant heat exchanger 23 as an internal heat exchanger can reduce the specific compressor power of the compressor 25 of the second refrigerant circuit 3 and simultaneously increase the specific cooling capacity of the first refrigerant circuit 2a and consequently the efficiency of the operation of the device 1a and thus of the air conditioning system of the motor vehicle.

[0070] The first refrigerant circuit 2a is always switched on during operation of the device 1a in different operating modes, while the second refrigerant circuit 3 can also be switched off as needed.

[0071] In the Fig. 2a and Fig. Figure 2b shows the device 1a during operation of the air conditioning system in refrigeration mode, i.e., cooling the air supplied to the passenger compartment. Fig. 2b also describes the operation of the air conditioning system with cooling of the powertrain components.

[0072] In the illustration of different operating modes of the device 1a, lines of the refrigerant circuits 2a, 3 supplied with refrigerant are marked with solid lines, while lines not supplied with refrigerant are marked with dashed lines.

[0073] When the device 1a is operated in refrigeration mode, the second refrigerant circuit 3 is switched such that the supply air flowing into the passenger compartment is cooled and dehumidified by means of the refrigerant-to-air heat exchangers 31, 35, which are operated as evaporators. The third refrigerant-to-air heat exchanger 31 serves to condition the air in the rear area of ​​the passenger compartment and is referred to as the rear evaporator 31 or rear evaporator, while the fourth refrigerant-to-air heat exchanger 35 serves to condition the air in the front area of ​​the passenger compartment and is referred to as the front evaporator or front evaporator. The expansion devices 30, 33, 34 are open.

[0074] The refrigerant circulating in the second refrigerant circuit 3 is compressed and pumped from a low-pressure level to a high-pressure level by the compressor 25. During the subsequent flow through the first refrigerant-to-refrigerant heat exchanger 18, the refrigerant is liquefied, specifically condensed / cooled, whereby heat is transferred from the refrigerant of the second refrigerant circuit 3 to the refrigerant of the first refrigerant circuit 2a. Following this, the refrigerant is divided into partial mass flows at the branch point 28 and introduced through the open expansion valves 30, 33 into the first flow path 26 and the second flow path 27 of the second refrigerant circuit 3.

[0075] In the first flow path 26 of the second refrigerant circuit 3, the refrigerant is expanded from the high-pressure level to the low-pressure level as it flows through the first expansion element 30 and is then directed through the rear evaporator 31. As it flows through the rear evaporator 31, the refrigerant evaporates, absorbing heat from an air mass flow supplied to the passenger compartment in the flow direction 38, which is thereby cooled.

[0076] In the second flow path 27 of the second refrigerant circuit 3, the refrigerant, as it flows through the second expansion element 33, is also expanded from the high-pressure level to the low-pressure level and passed through the refrigerant-to-air heat exchanger 35, which operates as a front evaporator. As it flows through the refrigerant-to-air heat exchanger 35, the refrigerant evaporates, absorbing heat from an air mass flow supplied to the passenger compartment in the flow direction 37, which is thereby cooled. The expansion element 34 downstream of the refrigerant-to-air heat exchanger 35 is fully open, so that the refrigerant flows through it without a change of state, in particular without expanding. The second refrigerant-to-refrigerant heat exchanger 23 is not used by the first refrigerant circuit 2a and is therefore inactive; no heat is transferred.

[0077] The partial mass flows of the refrigerant, now present at the low-pressure level, are mixed at the outlet 29 and drawn in by the compressor 25.

[0078] The refrigerant circulating in the first refrigerant circuit 2a is compressed and pumped from a low-pressure level to a high-pressure level by the compressor 4. When the device 1a is operating in refrigeration mode, the shut-off valves 6 and 7 of the valve arrangement 5 of the first refrigerant circuit 2a are configured such that the refrigerant is first routed through the refrigerant-to-air heat exchanger 11. The first shut-off valve 6 is open, while the second shut-off valve 7 is closed. The first flow path 9 of the first refrigerant circuit 2a is not supplied with refrigerant.

[0079] As the refrigerant flows through the refrigerant-to-air heat exchanger 11, also known as the ambient heat exchanger, it is liquefied, specifically condensed / cooled, whereby heat is transferred from the refrigerant of the first refrigerant circuit 2a to the ambient air flowing in the direction of flow 36. Subsequently, the refrigerant is introduced into the second flow path 13 through the open first expansion element 17 of the first refrigerant circuit 2a. As it flows through the first expansion element 17, the refrigerant expands from the high-pressure level to the low-pressure level and passes through the first refrigerant-to-refrigerant heat exchanger 18. As it flows through the refrigerant-to-refrigerant heat exchanger 18, the refrigerant of the first refrigerant circuit 2a evaporates, absorbing heat from the refrigerant of the second refrigerant circuit 3.

[0080] When operating the air conditioning system with device 1a in refrigeration mode and with cooling of drive train components according to Fig. 2b After exiting the refrigerant-air heat exchanger 11, the refrigerant is divided into partial mass flows at the branch point 15 and introduced through the open expansion devices 17, 19 into the second flow path 13 and the third flow path 14 of the first refrigerant circuit 2a. The first partial mass flow of the refrigerant is, as described above, Fig. As described in section 2a, the refrigerant is guided through the second flow path 13. In the third flow path 14 of the first refrigerant circuit 2a, the second partial mass flow of refrigerant is expanded from the high-pressure level to the low-pressure level as it flows through the second expansion element 19 and is then directed through the refrigerant-coolant heat exchanger 20. As it flows through the refrigerant-coolant heat exchanger 20, the refrigerant evaporates, absorbing heat from a coolant in a coolant circuit that also includes the components of the drive train. The coolant is thereby cooled.

[0081] According to an alternative embodiment, not shown, the refrigerant is evaporated directly by absorbing heat from the components of the drive train.

[0082] The partial mass flows of the refrigerant, now present at the low-pressure level, are mixed at the outlet 16 and directed into the accumulator 21. During operation of the air conditioning system according to Fig. 2a The refrigerant, which has been completely guided through the second flow path 13, is directed into the accumulator 21. Subsequently, the refrigerant is drawn from the accumulator 21 by the compressor 4.

[0083] When operating device 1a of the air conditioning system with exclusive cooling of components of the powertrain according to Fig. 2c Only the first refrigerant circuit 2a is active. The compressor 25 of the second refrigerant circuit 3 is out of operation.

[0084] The refrigerant circulating in the first refrigerant circuit 2a is compressed and pumped from a low-pressure level to a high-pressure level by the compressor 4. The shut-off valves 6 and 7 of the valve assembly 5 are configured such that the refrigerant is first routed through the refrigerant-to-air heat exchanger 11. The first shut-off valve 6 is open, while the second shut-off valve 7 is closed. The first flow path 9 of the first refrigerant circuit 2a is not supplied with refrigerant.

[0085] As the refrigerant flows through the refrigerant-air heat exchanger 11, it is liquefied, in particular condensed / cooled, whereby the heat is transferred from the refrigerant to the ambient air flowing in the direction of flow 36. Subsequently, the refrigerant is introduced into the third flow path 14 through the open second expansion element 19. The first expansion element 17 is closed, and the second flow path 13 is not supplied with refrigerant.

[0086] As the refrigerant flows through the second expansion element 19, it expands from the high-pressure level to the low-pressure level and passes through the first refrigerant-coolant heat exchanger 20, where it evaporates, absorbing heat from the coolant in the coolant circuit designed to regulate the temperature of drivetrain components. The coolant is thereby cooled. The refrigerant, having passed completely through the third flow path 14, is directed into the accumulator 21 and subsequently drawn in by the compressor 4.

[0087] In Fig. 3a is the device 1a according to Fig. 1 shown when the air conditioning system is operating in reheat mode, especially at ambient temperatures in the range of approximately 15°C to 25°C.

[0088] The second refrigerant circuit 3 is configured to cool and dehumidify the supply air flowing into the passenger compartment by means of the fourth refrigerant-to-air heat exchanger 35, which operates as an evaporator. The third refrigerant-to-air heat exchanger 31 is not supplied with refrigerant. The first expansion element 30, and thus the first flow path 26 of the second refrigerant circuit 3, is closed, while the expansion elements 33 and 34 of the second flow path 27 are open.

[0089] The refrigerant circulating in the second refrigerant circuit 3 is compressed and pumped from a low-pressure level to a high-pressure level by the compressor 25. During the subsequent flow through the first refrigerant-to-refrigerant heat exchanger 18, the refrigerant is liquefied, specifically condensed / cooled, whereby heat is transferred from the refrigerant of the second refrigerant circuit 3 to the refrigerant of the first refrigerant circuit 2a. Following this, the refrigerant is completely introduced into the second flow path 27 of the second refrigerant circuit 3 through the open second expansion valve 33.

[0090] As the refrigerant flows through the second expansion element 33, it expands from the high-pressure level to the low-pressure level and passes through the refrigerant-to-air heat exchanger 35, which acts as an evaporator. During this flow, the refrigerant evaporates, absorbing heat from an air mass flow supplied to the passenger compartment in the direction of flow 37. This air mass flow is thereby dehumidified and / or cooled. The expansion element 34 downstream of the refrigerant-to-air heat exchanger 35 is fully open, allowing the refrigerant to flow through without a change of state, in particular without expansion. During the subsequent flow through the second refrigerant-to-refrigerant heat exchanger 23, heat is transferred from the refrigerant of the first refrigerant circuit 2a to the refrigerant of the second refrigerant circuit 3, which is at the low-pressure level.The refrigerant in the second refrigerant circuit 3 is, if necessary, further evaporated and subsequently superheated. The superheated refrigerant is drawn in by the compressor 25.

[0091] The refrigerant circulating in the first refrigerant circuit 2a is compressed and pumped from a low-pressure level to a high-pressure level by the compressor 4. During operation of the device 1a in post-heating mode after Fig. 3a The shut-off valves 6, 7 of the valve arrangement 5 of the first refrigerant circuit 2a are connected such that a first partial mass flow of the refrigerant is initially directed through the refrigerant-air heat exchanger 11, while a second partial mass flow enters the first flow path 9. The shut-off valves 6, 7 of the valve arrangement 5 are open.

[0092] As the refrigerant flows through the first refrigerant-air heat exchanger 11, which is operated as a condenser / gas cooler, the refrigerant of the first partial mass flow is liquefied, in particular condensed / cooled, whereby heat is transferred from the refrigerant of the first refrigerant circuit 2a to the ambient air flowing in the direction of flow 36.

[0093] The refrigerant of the second partial mass flow, which passes through the first flow path 9 of the first refrigerant circuit 2a, is also liquefied, in particular condensed / cooled, as it flows through the second refrigerant-to-air heat exchanger 22a, which operates as a condenser / gas cooler. Heat is transferred from the refrigerant of the first refrigerant circuit 2a to the supply air for the passenger compartment flowing in the direction of flow 37. The supply air, which was previously cooled or dehumidified when flowing over the heat transfer surface of the fourth refrigerant-to-air heat exchanger 35, which operates as an evaporator, is reheated when flowing over the heat transfer surface of the refrigerant-to-air heat exchanger 22a.

[0094] The at least partially liquefied / cooled refrigerant flowing out of the refrigerant-air heat exchanger 22a is then passed through the second refrigerant-refrigerant heat exchanger 23 for further liquefaction / condensation and, if necessary, subcooling, whereby heat is transferred from the refrigerant of the first refrigerant circuit 2a, which is at the high-pressure level, to the refrigerant of the second refrigerant circuit 3.

[0095] The partial mass flows of the refrigerant of the first refrigerant circuit 2a, each present at the high-pressure level, are mixed at the outlet 10.

[0096] Subsequently, the refrigerant is introduced into the second flow path 13 through the open first expansion element 17 of the first refrigerant circuit 2a. As it flows through the first expansion element 17, the refrigerant expands from the high-pressure level to the low-pressure level and passes through the first refrigerant-to-refrigerant heat exchanger 18. During this passage through the refrigerant-to-refrigerant heat exchanger 18, the refrigerant of the first refrigerant circuit 2a evaporates, absorbing heat from the refrigerant of the second refrigerant circuit 3. The second expansion element 19 of the third flow path 14 is closed. The third flow path 14 and the refrigerant-to-refrigerant heat exchanger 20 located therein are not supplied with refrigerant. The refrigerant, having passed completely through the second flow path 13, is directed into the accumulator 21 and drawn from the accumulator 21 by the compressor 4.

[0097] Fig. 3b shows the device 1a according to Fig. 1 when operating the air conditioning system in reheat mode, especially at ambient temperatures in the range of approximately 5°C to 15°C, and with cooling of components of the powertrain.

[0098] The second refrigerant circuit 3 is operated as in the operation of the device 1a of the air conditioning system according to Fig. 3a switched, so that in this regard reference is made to the explanations regarding Fig. 3a is referred to.

[0099] The refrigerant circulating in the first refrigerant circuit 2a is compressed and pumped from a low-pressure level to a high-pressure level by the compressor 4. During operation of the device 1a in post-heating mode after Fig. 3b The shut-off valves 6, 7 of the valve arrangement 5 of the first refrigerant circuit 2a are connected such that the refrigerant is routed exclusively through the first flow path 9. The first shut-off valve 6 is closed, while the second shut-off valve 7 is open. The first refrigerant-to-air heat exchanger 11 is not supplied with refrigerant. The refrigerant routed through the first flow path 9 of the first refrigerant circuit 2a is liquefied, in particular condensed / cooled, as it flows through the second refrigerant-to-air heat exchanger 22a, which is operated as a condenser / gas cooler, whereby heat is transferred from the refrigerant of the first refrigerant circuit 2a to the supply air flowing in the direction of flow 37 for the passenger compartment.The supply air, which was previously cooled or dehumidified when flowing over the heat transfer surface of the fourth refrigerant-air heat exchanger 35, which is operated as an evaporator, is reheated when flowing over the heat transfer surface of the refrigerant-air heat exchanger 22a.

[0100] The at least partially liquefied / cooled refrigerant flowing out of the refrigerant-air heat exchanger 22a is then passed through the second refrigerant-refrigerant heat exchanger 23 for further liquefaction / condensation and, if necessary, subcooling, whereby heat is transferred from the refrigerant of the first refrigerant circuit 2a, which is at the high-pressure level, to the refrigerant of the second refrigerant circuit 3.

[0101] The refrigerant, which is present at the high-pressure level, is divided into partial mass flows at the branch point 15 after flowing out of the refrigerant-refrigerant heat exchanger 23 and introduced through the opened expansion devices 17, 19 into the second flow path 13 and the third flow path 14 of the first refrigerant circuit 2a.

[0102] As the refrigerant flows through the first expansion element 17, it is expanded from the high-pressure level to the low-pressure level and passed through the first refrigerant-to-refrigerant heat exchanger 18, whereby the refrigerant evaporates while absorbing heat from the refrigerant of the second refrigerant circuit 3.

[0103] The second partial mass flow of the refrigerant is expanded from the high-pressure level to the low-pressure level in the third flow path 14 of the first refrigerant circuit 2a as it flows through the second expansion element 19 and is then passed through the refrigerant-coolant heat exchanger 20. As it flows through the refrigerant-coolant heat exchanger 20, the refrigerant evaporates, absorbing heat from the coolant of a coolant circuit, which also includes the components of the drive train. The coolant is thereby cooled.

[0104] The partial mass flows of the refrigerant present at the low-pressure level are mixed at the outlet 16 and directed into the accumulator 21. Subsequently, the refrigerant is drawn from the accumulator 21 by the compressor 4.

[0105] During operation of the device 1a, in particular the first refrigerant circuit 2a, in a first heat pump mode and with cooling of components of the drive train according to Fig. In 4a, only the first refrigerant circuit 2a is active. The compressor 25 of the second refrigerant circuit 3 is out of operation. The refrigerant circulating in the first refrigerant circuit 2a is compressed and pumped by the compressor 4 from a low-pressure level to a high-pressure level. The shut-off valves 6, 7 of the valve assembly 5 of the first refrigerant circuit 2a are configured such that the refrigerant is directed exclusively through the first flow path 9. The first shut-off valve 6 is closed, while the second shut-off valve 7 is open. The first refrigerant-to-air heat exchanger 11 is not supplied with refrigerant.

[0106] The refrigerant, which flows through the first flow path 9 of the first refrigerant circuit 2a, is liquefied, in particular condensed / cooled and optionally subcooled, as it passes through the second refrigerant-air heat exchanger 22a, which is operated as a condenser / gas cooler. Heat is transferred from the refrigerant of the first refrigerant circuit 2a to the supply air for the passenger compartment flowing in the direction of flow 37. The supply air is heated.

[0107] Since the second refrigerant-to-refrigerant heat exchanger 23 is not traversed by the first refrigerant circuit 2a and is therefore inactive, no heat is transferred in the second refrigerant-to-refrigerant heat exchanger 23. The refrigerant flowing out of the refrigerant-to-air heat exchanger 22a or the refrigerant-to-refrigerant heat exchanger 23 is introduced into the third flow path 14 through the open second expansion valve 19. The first expansion valve 17 is closed, and the second flow path 13 is not supplied with refrigerant. As the refrigerant flows through the second expansion valve 19, it expands from the high-pressure level to the low-pressure level and passes through the first refrigerant-to-coolant heat exchanger 20, in which the refrigerant evaporates, absorbing heat from the coolant of the coolant circuit designed for temperature control of drivetrain components. The coolant is thereby cooled.The refrigerant, which has passed completely through the third flow path 14, is directed into the accumulator 21 and then drawn in by the compressor 4.

[0108] In Fig. 4b is the device 1a according to Fig. Figure 1 shows the operation of the air conditioning system in a second heat pump mode. The second refrigerant circuit 3 is configured to preheat the supply air flowing into the passenger compartment by means of the fourth refrigerant-to-air heat exchanger 35, which operates as a condenser / gas cooler. The third refrigerant-to-air heat exchanger 31 is not supplied with refrigerant. The first expansion element 30, and thus the first flow path 26 of the second refrigerant circuit 3, is closed, while the expansion elements 33 and 34 of the second flow path 27 are open.

[0109] The refrigerant circulating in the second refrigerant circuit 3 is compressed and pumped from a low-pressure level to a high-pressure level by the compressor 25. During the subsequent flow through the first refrigerant-to-refrigerant heat exchanger 18, the refrigerant is liquefied, specifically condensed / cooled, whereby heat is transferred from the refrigerant of the second refrigerant circuit 3 to the refrigerant of the first refrigerant circuit 2a. Following this, the refrigerant is completely introduced into the second flow path 27 of the second refrigerant circuit 3 through the fully opened second expansion element 33. The refrigerant does not undergo a change of state in the second expansion element 33.

[0110] As the refrigerant flows through the fourth refrigerant-air heat exchanger 35, which operates as a condenser / gas cooler, it is further liquefied, in particular condensed / cooled, whereby the heat is transferred from the refrigerant to the supply air flowing in the direction of flow 37 for the passenger compartment. The supply air is preheated.

[0111] As the refrigerant flows through the third expansion element 34, it expands from the high-pressure level to the low-pressure level and passes through the second refrigerant-to-refrigerant heat exchanger 23. As it flows through the refrigerant-to-refrigerant heat exchanger 18, the refrigerant of the second refrigerant circuit 3 evaporates, absorbing heat from the refrigerant of the first refrigerant circuit 2a. Heat is transferred from the refrigerant of the first refrigerant circuit 2a to the refrigerant of the second refrigerant circuit 3, which is at the low-pressure level. The evaporated and, if applicable, superheated refrigerant is drawn in by the compressor 25.

[0112] The first refrigerant circuit 2a is as in the operation of the device 1a of the air conditioning system according to Fig. 3b switched on, so that in this regard reference is made to the explanations regarding Fig. 3b is referred to.

[0113] A difference from the operating mode of the air conditioning system according to Fig. 3b lies in the fact that the refrigerant, which is carried through the first flow path 9 of the first refrigerant circuit 2a, is liquefied, in particular condensed / cooled, when flowing through the second refrigerant-air heat exchanger 22a, which is operated as a condenser / gas cooler, whereby heat is transferred from the refrigerant of the first refrigerant circuit 2a to the supply air for the passenger compartment flowing in the direction of flow 37. The supply air, which was already preheated when flowing over the heat transfer surface of the fourth refrigerant-air heat exchanger 35, which is operated as a condenser / gas cooler, is further heated when flowing over the heat transfer surface of the refrigerant-air heat exchanger 22a.

[0114] Another difference from the operating mode of the air conditioning system according to Fig. 3b consists in the fact that the at least partially liquefied / cooled refrigerant flowing out of the refrigerant-air heat exchanger 22a is passed through the second refrigerant-refrigerant heat exchanger 23 for further liquefaction / condensation and, if necessary, for subcooling, whereby heat is transferred from the refrigerant of the first refrigerant circuit 2a, which is present at the high-pressure level, to the refrigerant of the second refrigerant circuit 3, which is present in the two-phase region immediately after expansion in the third expansion element 34 of the second refrigerant circuit 3 and evaporates.

[0115] Fig. Figure 4c shows the device 1a according to Fig. 1 when operating the air conditioning system in a third heat pump mode with maximum heating power for the supply air of the passenger compartment.

[0116] The second refrigerant circuit 3 is, as in the operating mode after Fig. 4b, is configured to preheat the supply air flowing into the passenger compartment by means of the fourth refrigerant-to-air heat exchanger 35, which operates as a condenser / gas cooler. The third refrigerant-to-air heat exchanger 31 is not supplied with refrigerant. The first expansion element 30, and thus the first flow path 26 of the second refrigerant circuit 3, is closed, while the expansion elements 33 and 34 of the second flow path 27 are open.

[0117] In contrast to the operation of the air conditioning system in the second heat pump mode after Fig. 4b The first refrigerant-to-refrigerant heat exchanger 18 is not active. The first refrigerant-to-refrigerant heat exchanger 18 is not supplied with refrigerant by the first refrigerant circuit 2a, consequently no heat is transferred.

[0118] The refrigerant circulating in the second refrigerant circuit 3 is compressed and pumped from a low-pressure level to a high-pressure level by the compressor 25. During the subsequent flow through the first refrigerant-to-refrigerant heat exchanger 18, the refrigerant does not undergo a change of state, as the first refrigerant-to-refrigerant heat exchanger 18 is not supplied with refrigerant from the first refrigerant circuit 2a. The refrigerant is then fully introduced into the second flow path 27 of the second refrigerant circuit 3 through the fully opened second expansion valve 33. The refrigerant also does not undergo a change of state in the second expansion valve 33.

[0119] As the refrigerant flows through the fourth refrigerant-air heat exchanger 35, which is operated as a condenser / gas cooler, it is liquefied, in particular condensed / cooled, whereby the heat is transferred from the refrigerant to the supply air flowing in the direction of flow 37 for the passenger compartment. The supply air is preheated.

[0120] As the refrigerant flows through the third expansion element 34, it expands from the high-pressure level to the low-pressure level and passes through the second refrigerant-to-refrigerant heat exchanger 23. As it flows through the refrigerant-to-refrigerant heat exchanger 18, the refrigerant of the second refrigerant circuit 3 evaporates, absorbing heat from the refrigerant of the first refrigerant circuit 2a. Heat is transferred from the refrigerant of the first refrigerant circuit 2a to the refrigerant of the second refrigerant circuit 3, which is at the low-pressure level. The evaporated and, if applicable, superheated refrigerant is drawn in by the compressor 25.

[0121] The refrigerant circulating in the first refrigerant circuit 2a is compressed and pumped from a low-pressure level to a high-pressure level by the compressor 4. When the device 1a is operating in the third heat pump mode with maximum heating capacity for the passenger compartment's supply air, Fig. 4c The shut-off valves 6 and 7 of the valve arrangement 5 of the first refrigerant circuit 2a are configured such that the refrigerant is routed exclusively through the first flow path 9. The first shut-off valve 6 is closed, while the second shut-off valve 7 is open. The first refrigerant-to-air heat exchanger 11 is not supplied with refrigerant.

[0122] The refrigerant flowing through the first flow path 9 of the first refrigerant circuit 2a is liquefied, specifically condensed / cooled, as it flows through the second refrigerant-to-air heat exchanger 22a, which operates as a condenser / gas cooler. Heat is transferred from the refrigerant of the first refrigerant circuit 2a to the supply air flowing in the direction of flow 37 for the passenger compartment. The supply air, which was already preheated when flowing over the heat transfer surface of the fourth refrigerant-to-air heat exchanger 35, which also operates as a condenser / gas cooler, is further heated when flowing over the heat transfer surface of the refrigerant-to-air heat exchanger 22a.

[0123] The at least partially liquefied / cooled refrigerant flowing out of the refrigerant-air heat exchanger 22a is then passed through the second refrigerant-refrigerant heat exchanger 23 for further liquefaction / condensation and, if necessary, subcooling, whereby heat is transferred from the refrigerant of the first refrigerant circuit 2a, which is at the high-pressure level, to the refrigerant of the second refrigerant circuit 3, which is in the two-phase region immediately after expansion in the third expansion element 34 of the second refrigerant circuit 3 and evaporates.

[0124] The refrigerant flowing from the second refrigerant-to-refrigerant heat exchanger 23 of the second refrigerant circuit 3 is introduced into the third flow path 14 through the open second expansion valve 19. The first expansion valve 17 is closed, and the second flow path 13 is not supplied with refrigerant. As the refrigerant flows through the second expansion valve 19, it expands from the high-pressure level to the low-pressure level and passes through the first refrigerant-to-coolant heat exchanger 20, where it evaporates, absorbing heat from the coolant of the coolant circuit designed to regulate the temperature of drivetrain components. The coolant is thereby cooled. The refrigerant, having passed completely through the third flow path 14, is directed into the accumulator 21 and subsequently drawn in by the compressor 4.

[0125] Fig. Figure 5 shows a device 1b for an air conditioning system of a motor vehicle with a first refrigerant circuit 2a and a second refrigerant circuit 3 as well as a coolant circuit 39a with a heat exchanger 41. The refrigerant circuits 2a, 3 are, as in the device according to Fig. 1, thermally coupled to each other via two refrigerant-to-refrigerant heat exchangers 18, 23 and arranged in a cascade circuit.

[0126] In contrast to device 1a according to Fig. 1 is the second heat exchanger, which can be operated as a condenser / gas cooler, designed as a refrigerant-to-coolant heat exchanger 22b instead of the refrigerant-to-air heat exchanger 22a. The refrigerant-to-coolant heat exchanger 22b is a component of the refrigerant circuit 39a.

[0127] The heat transferred from the refrigerant to the coolant in the refrigerant-coolant heat exchanger 22b is transported by the coolant, acting as a heat transfer medium, to a heating heat exchanger 41, which is arranged, for example, in place of the refrigerant-air heat exchanger 22a of the device 1a in an air conditioning unit. Depending on the operating mode and requirements, the supply air for the passenger compartment supplied by the air conditioning unit can be heated as it flows over the heat transfer surface of the heating heat exchanger 41. The coolant is circulated through the coolant circuit by means of a conveying device 40, in particular a pump.

[0128] In Fig. Figure 6 shows a device 1c for an air conditioning system of a motor vehicle with a first refrigerant circuit 2c and a second refrigerant circuit 3, as well as a coolant circuit 39b with a heat exchanger 41 and a coolant-to-air heat exchanger 46 for transferring heat to ambient air. The refrigerant circuits 2c and 3 are similar to the device 1a according to Figure 6. Fig. 1 and the device 1b according to Fig. 5, thermally coupled to each other via two refrigerant-to-refrigerant heat exchangers 18, 23 and arranged in a cascade circuit.

[0129] In contrast to device 1a according to Fig. 1 and to device 1b according to Fig. In section 5, the first refrigerant circuit 2c does not have a refrigerant-to-air heat exchanger 11 that can be operated as a condenser / gas cooler. Therefore, the first refrigerant circuit 2c is designed without the valve arrangement 5 for dividing the refrigerant compressed at high pressure, as well as the check valves 12, 24. The first flow path 9 preferably extends to the branch point 15.

[0130] In contrast to device 1b according to Fig.In section 5, the coolant circuit 39b includes the coolant-to-air heat exchanger 46, which serves as an ambient heat exchanger instead of the refrigerant-to-air heat exchanger 11 of the first refrigerant circuit 2a. The coolant circuit 39b is configured with a first coolant path 42 and a second coolant path 43, wherein the heating heat exchanger 41 is located within the first coolant path 42 and the coolant-to-air heat exchanger 46 is located within the second coolant path 43. The coolant paths 42 and 43 each extend from a branch point 44 to a terminal point 45 and run parallel to each other, so that the heating heat exchanger 41 and the coolant-to-air heat exchanger 46 are arranged parallel to each other and can be supplied with coolant in parallel. The coolant is conveyed through the coolant circuit by means of the conveying device 40, in particular a pump.

[0131] The condensation / cooling heat to be removed from the first refrigerant circuit 2c is transferred by device 1c, regardless of the operating mode of the air conditioning system, first to the refrigerant circulating in the coolant circuit via the refrigerant-coolant heat exchanger 22b. Depending on the operating mode, the heat removed to the refrigerant is transferred to the ambient air when flowing through the refrigerant-air heat exchanger 46, for example, when the air conditioning system is operating in a refrigeration mode or with cooling of the powertrain components, or to the supply air for the passenger compartment when flowing through the heating heat exchanger 41, for example, when the air conditioning system is operating in a heat pump mode or a post-heating mode.

[0132] In order to distribute the heat to be carried away by the coolant, especially when the air conditioning system is operating in a post-heating mode, to the heating heat exchanger 41 and the coolant-air heat exchanger 46, the branch point of the coolant circuit 39b is designed as a controllable three-way valve so that the coolant mass flow can be divided between the coolant paths 42, 43.

[0133] Using device 1b or device 1c, for example, a standard air conditioning unit from conventional motor vehicles can be used cost-effectively. Reference symbol list 1a, 1b, 1c Device 2a, 2c first refrigerant circuit 3 second refrigerant circuit 4 Compressors first refrigerant circuit 2 5 Valve arrangement 6 first shut-off valve valve arrangement 5 7 second shut-off valve valve arrangement 5 8 first branch point first refrigerant circuit 2 9 First flow path, first refrigerant circuit 2 10 first outlet first refrigerant circuit 2 11. First condenser / gas cooler, refrigerant-to-air heat exchanger 12 first check valve first refrigerant circuit 2 13 Second flow path, first refrigerant circuit 2 14 third flow path first refrigerant circuit 2 15 second branch point first refrigerant circuit 2 16 second outlet first refrigerant circuit 2 17 first expansion device first refrigerant circuit 2 18 first refrigerant-to-refrigerant heat exchanger 19 second expansion valve first refrigerant circuit 2 20 refrigerant-to-refrigerant heat exchangers 21 Accumulator first refrigerant circuit 2 22a Second condenser / gas cooler, refrigerant-to-air heat exchanger 22b second condenser / gas cooler, refrigerant-to-coolant heat exchanger 23 second refrigerant-to-refrigerant heat exchanger 24 second check valve first refrigerant circuit 2 25 Compressors, second refrigerant circuit 3 26 first flow path second refrigerant circuit 3 27 Second flow path, second refrigerant circuit 3 28 Branch point second refrigerant circuit 3 29 Outlet point of second refrigerant circuit 3 30 first expansion valve second refrigerant circuit 3 31 Evaporator, third refrigerant-to-air heat exchanger 32 Check valve second refrigerant circuit 3 33 Second expansion valve, second refrigerant circuit 3 34 third expansion valve second refrigerant circuit 3 35 fourth refrigerant-to-air heat exchanger 36 Flow direction of ambient air 37 Flow direction Supply air Front 38 Flow direction Supply air Rear area 39a, 39b Coolant circuit 40 Conveyor device 41 Heat exchangers 42 First coolant path Coolant circuit 39b 43 Second coolant path Coolant circuit 39b 44 Coolant circuit branch 39b 45 Discharge point of coolant circuit 39b 46 Coolant-to-air heat exchangers

Claims

[1] Device (1a, 1b, 1c) for an air conditioning system of a motor vehicle, comprising at least one first refrigerant circuit (2a, 2c) and a second refrigerant circuit (3), which are thermally connected to each other via a first refrigerant-to-refrigerant heat exchanger (18) for heat transfer from a refrigerant of the second refrigerant circuit (3) to a refrigerant of the at least one first refrigerant circuit (2a, 2c) and a second refrigerant-to-refrigerant heat exchanger (23) for heat transfer from the refrigerant of the at least one first refrigerant circuit (2a, 2c) to the refrigerant of the second refrigerant circuit (3), wherein - the at least one first refrigerant circuit (2a, 2c) is designed in a flow direction of the refrigerant with a compressor (4), the second refrigerant-to-refrigerant heat exchanger (23), the first refrigerant-to-refrigerant heat exchanger (18) and a heat exchanger (20) that can be operated as an evaporator, wherein a first expansion element (17) is arranged upstream of the first refrigerant-to-refrigerant heat exchanger (18) and a second expansion element (19) is arranged upstream of the heat exchanger (20), - the second refrigerant circuit (3) is designed in a refrigerant flow direction with a compressor (25), the first refrigerant-to-refrigerant heat exchanger (18), at least one expansion element (33), a refrigerant-to-air heat exchanger (35) for heat transfer between the refrigerant and a supply air for a passenger compartment, and the second refrigerant-to-refrigerant heat exchanger (23), wherein the second refrigerant-to-refrigerant heat exchanger (23) is arranged with an upstream expansion element (34) in the refrigerant flow direction downstream of the refrigerant-to-air heat exchanger (35). [2] Device (1a, 1b, 1c) according to claim 1, characterized by , that the at least one first refrigerant circuit (2a, 2c) is formed with a heat exchanger (22a, 22b) which is arranged within a first flow path (9) in the direction of flow of the refrigerant upstream of the second refrigerant-to-refrigerant heat exchanger (23). [3] Device (1a) according to claim 2, characterized by , that the heat exchanger (22a, 22b) is designed as a refrigerant-to-air heat exchanger (22a) for heating supply air for a passenger compartment. [4] Device (1b, 1c) according to claim 2, characterized by , that the heat exchanger (22a, 22b) is designed as a refrigerant-coolant heat exchanger (22b) of a refrigerant circuit for heat transfer from the refrigerant of the at least one first refrigerant circuit (2a) to the refrigerant. [5] Device (1b, 1c) according to claim 4, characterized by , that the coolant circuit of the refrigerant-coolant heat exchanger (22b) is designed with a heating heat exchanger (41) for heating supply air for a passenger compartment. [6] Device (1c) according to claim 4 or 5, characterized by, that the coolant circuit of the refrigerant-coolant heat exchanger (22b) is designed with a coolant-air heat exchanger (46) for heat transfer from the coolant to ambient air. [7] Device (1a, 1b) according to any one of claims 2 to 5, characterized by , that the at least one first refrigerant circuit (2a) has a valve arrangement (5) with a first branch point (8) and a first outlet point (10), wherein the first flow path (9) and a flow path with a refrigerant-air heat exchanger (11) for heat transfer from the refrigerant of the at least one first refrigerant circuit (2a) to ambient air are arranged extending between the first branch point (8) and the first outlet point (10). [8] Device (1a, 1b, 1c) according to any one of claims 2 to 7, characterized by, that the first refrigerant-to-refrigerant heat exchanger (18) and the first expansion element (17) arranged upstream of the first refrigerant-to-refrigerant heat exchanger (18) in the flow direction of the refrigerant of the at least one first refrigerant circuit (2a, 2c) are located within a second flow path (13), and that the heat exchanger (20) and the second expansion element (19) arranged upstream of the heat exchanger (20) in the flow direction of the refrigerant of the at least one first refrigerant circuit (2a, 2c) are located within a third flow path (14), wherein the flow paths (13, 14) extend from a second branch point (15) to a second outlet point (16) of the at least one first refrigerant circuit (2a, 2c) and are arranged parallel to each other. [9] Device (1a, 1b, 1c) according to any one of claims 1 to 8, characterized by, that the heat exchanger (20) is designed as a refrigerant-coolant heat exchanger of a coolant circuit for temperature control of components of a motor vehicle powertrain. [10] Device (1a, 1b, 1c) according to any one of claims 1 to 9, characterized by , that the second refrigerant circuit (3) is designed with a refrigerant-air heat exchanger (31) for heat transfer between the refrigerant of the second refrigerant circuit (3) and the supply air for a passenger compartment, wherein a first expansion element (30) is arranged upstream of the refrigerant-air heat exchanger (31) in the direction of flow of the refrigerant. [11] Device (1a, 1b, 1c) according to claim 10, characterized by , that - the refrigerant-to-air heat exchanger (31) and the first expansion element (30) arranged upstream of the refrigerant-to-air heat exchanger (31) in the flow direction of the refrigerant of the second refrigerant circuit (3) within a first flow path (26) as well as - the refrigerant-air heat exchanger (35), a second expansion element (33) arranged upstream of the refrigerant-air heat exchanger (35) in the flow direction of the refrigerant of the second refrigerant circuit (3), as well as the second refrigerant-refrigerant heat exchanger (23) and a third expansion element (34) arranged upstream of the second refrigerant-refrigerant heat exchanger (23) in the flow direction of the refrigerant of the second refrigerant circuit (3) are formed within a second flow path (27), wherein the flow paths (26, 27) extend from a branch point (28) to a discharge point (29) of the second refrigerant circuit (3) and are arranged parallel to each other. [12] Method for operating the device (1a, 1b, 1c) for an air conditioning system of a motor vehicle according to any one of claims 1 to 11, wherein the air conditioning system is configured for operation in a refrigeration mode, a heat pump mode and a reheating mode for conditioning the air of a passenger compartment of a motor vehicle, characterized by , that when operating in a refrigeration system mode of the air conditioning system, heat is transferred at a first medium temperature level from coolant circulating in a coolant circuit to refrigerant of a first refrigerant circuit (2a, 2c) in a heat exchanger (20) designed as a refrigerant-coolant heat exchanger, and heat is transferred at a low temperature level from a supply air for the passenger compartment to refrigerant of a second refrigerant circuit (3) in at least one refrigerant-air heat exchanger (31, 35). [13] Method for operating the device (1a, 1b, 1c) for an air conditioning system of a motor vehicle according to any one of claims 1 to 11, wherein the air conditioning system is configured for operation in a refrigeration mode, a heat pump mode and a reheating mode for conditioning the air of a passenger compartment of a motor vehicle, characterized by, that when operating in a post-heating mode of the air conditioning system, heat is transferred at a low temperature level in a refrigerant-to-air heat exchanger (35) from a supply air for the passenger compartment to refrigerant of a second refrigerant circuit (3), and at a high temperature level in a refrigerant-to-air heat exchanger (22a) from a refrigerant of a first refrigerant circuit (2a, 2c) directly to supply air for the passenger compartment, or in a refrigerant-to-coolant heat exchanger (22b) heat is transferred to a coolant circulating in a coolant circuit, and in a heating heat exchanger (41) heat is transferred from the coolant to supply air for the passenger compartment. [14] Method for operating the device (1a, 1b, 1c) according to claim 13, characterized by, that in a heat exchanger (20) designed as a refrigerant-coolant heat exchanger, heat is transferred at a first intermediate temperature level from coolant circulating in a coolant circuit to the refrigerant of the first refrigerant circuit (2a, 2c). [15] Method for operating the device (1a, 1b, 1c) for an air conditioning system of a motor vehicle according to any one of claims 1 to 11, wherein the air conditioning system is configured for operation in a refrigeration mode, a heat pump mode and a post-heating mode for conditioning the air of a passenger compartment of a motor vehicle, characterized by, that when operating in a heat pump mode of the air conditioning system, heat is transferred at a high temperature level in a refrigerant-to-air heat exchanger (22a) from a refrigerant of a first refrigerant circuit (2a, 2c) directly to supply air for the passenger compartment, or in a refrigerant-to-coolant heat exchanger (22b) to a coolant circulating in a coolant circuit, and in a heating heat exchanger (41) to the coolant circulating in a supply air for the passenger compartment, and in a heat exchanger (20) designed as a refrigerant-to-coolant heat exchanger at a first medium temperature level, heat is transferred from coolant circulating in a coolant circuit to the refrigerant of the first refrigerant circuit (2a, 2c). [16] Method for operating the device (1a, 1b, 1c) according to claim 15, characterized by, that in a refrigerant-air heat exchanger (35) at a second intermediate temperature level, heat is transferred from a refrigerant of a second refrigerant circuit (3) to supply air for the passenger compartment, so that the supply air for the passenger compartment is preheated when flowing through the refrigerant-air heat exchanger (22a) or the heating heat exchanger (41) and is heated to a final temperature when flowing through the refrigerant-air heat exchanger (35). [17] Method for operating the device (1a, 1b, 1c) according to one of claims 12 or 14 to 16, characterized by , that the heat to be dissipated from electrical components of a motor vehicle powertrain is transferred to the coolant circulating in the coolant circuit and the heat is transferred in the heat exchanger (20) designed as a refrigerant-coolant heat exchanger at the first mean temperature level from the coolant to the refrigerant of the first refrigerant circuit (2a, 2c). [18] Method for operating the device (1a, 1b, 1c) according to any one of claims 12 to 17, characterized by , that in a first refrigerant-to-refrigerant heat exchanger (18) heat is transferred from refrigerant of a second refrigerant circuit (3) to refrigerant of the first refrigerant circuit (2a, 2b) and that in a second refrigerant-to-refrigerant heat exchanger (23) heat is transferred from the refrigerant of the first refrigerant circuit (2a, 2c) to the refrigerant of the second refrigerant circuit (3), wherein - in the first refrigerant-to-refrigerant heat exchanger (18) the refrigerant of the first refrigerant circuit (2a, 2c) is evaporated and the refrigerant of the second refrigerant circuit (3) is condensed / cooled, as well as - in the second refrigerant-to-refrigerant heat exchanger (23) the refrigerant of the first refrigerant circuit (2a, 2b) is condensed / cooled and the refrigerant of the second refrigerant circuit (3) is evaporated and / or superheated.

Images