Air-conditioning system for a vehicle

Abstract

The invention relates to an air-conditioning system for a vehicle, in particular a battery-electric or hybrid-electric, multitrack vehicle, having a radiator circuit (10), an air-conditioning circuit (20) and a compressor circuit (30), in each of which a refrigerant circulates, wherein the compressor circuit (30) is coupled in a temperature-transmitting manner to the radiator circuit (10) via a first heat exchanger (31) and to the air-conditioning circuit (20) via a second heat exchanger (32), and wherein the refrigerant of the radiator circuit (10) and / or of the air-conditioning circuit (20) comprises carbon dioxide, in particular R744.

Description

[0001] Air conditioning system for a vehicle

[0002] The invention relates to an air conditioning system for a vehicle, in particular for a battery-electric or hybrid-electric, multi-track vehicle. The invention further relates to a vehicle with such an air conditioning system.

[0003] Climate control in modern vehicles, especially battery-electric and hybrid-electric vehicles, presents particular challenges. On the one hand, climate control systems should be as energy-efficient as possible. On the other hand, a comfortable temperature should be reached as quickly as possible. With regard to energy efficiency, heat pump technologies are becoming increasingly prevalent, as they generate a large portion of the heating or cooling energy from ambient heat. This reduces the demand for electrical energy and thus improves the range of battery-electric vehicles in particular.

[0004] Conventional air conditioning systems typically use a refrigeration circuit filled with tetrafluoroethane, or R134a. However, such refrigerants are no longer desirable in automotive air conditioning systems because, particularly in the event of accidents, there is an increased risk of these climate-damaging refrigerants escaping into the environment. Therefore, stationary air conditioning systems often already use natural refrigerants such as propane or R290. These refrigerants are flammable, however, which is considered problematic for their use in mobile applications. Regulatory requirements stipulate that only a limited volume of flammable refrigerant may be used in a vehicle air conditioning system. Consequently, such a refrigerant is usually only used for the primary circuit of the heat pump system.For secondary circuits, especially for transferring heat energy or cold energy to a vehicle interior, other refrigerants, in particular a mixture of water and glycol, have been used so far.

[0005] 102316-WO - MSP Keller Schneider August 8, 2025 Patent Attorneys GmbH It has been shown that a water-glycol mixture as a secondary fluid has disadvantages, particularly regarding the start-up behavior of a heat pump, the dynamics of heat transfer, and the pump's performance. Furthermore, using a water-glycol mixture as a secondary fluid requires relatively large pipe cross-sections, which leads to increased space requirements in a vehicle. These disadvantages arise primarily from the viscosity behavior of the water-glycol mixture and the inertia of the system associated with the relatively high fluid volumes required.

[0006] The invention is therefore based on the objective of providing an air conditioning system for vehicles that exhibits improved efficiency and requires little space. Furthermore, it is an object of the invention to provide a vehicle equipped with such an air conditioning system.

[0007] According to the invention, this problem is solved with regard to the air conditioning system by the subject matter of claim 1 and with regard to the vehicle by the subject matter of claim 12.

[0008] Specifically, the invention is based on the concept of providing an air conditioning system for a vehicle, in particular a battery-electric or hybrid-electric multi-track vehicle, comprising a radiator circuit, an air conditioning circuit, and a compressor circuit. A refrigerant circulates in each of the radiator, air conditioning, and compressor circuits. The compressor circuit is coupled to the radiator circuit via a first heat exchanger and to the air conditioning circuit via a second heat exchanger for temperature transfer. The refrigerant in the radiator circuit and / or the air conditioning circuit comprises carbon dioxide, in particular R744.

[0009] It has been shown that carbon dioxide offers significant advantages as an evaporating refrigerant compared to previously known water-glycol mixtures. In particular, the use of carbon dioxide in the secondary circuit, especially in the radiator circuit and / or air conditioning circuit, leads to a significantly reduced [energy consumption / cost of carbon dioxide].

[0010] 102316-WO - MSP Keller Schneider August 8, 2025 Patent Attorneys GmbH Pumping work. The corresponding pumps can therefore be designed to be less powerful and thus more energy-efficient. Specifically, the pumping work can be reduced by approximately 90% compared to water-glycol mixtures. This leads to significant energy savings, which is particularly advantageous for the overall efficiency of battery-electric or hybrid-electric vehicles.

[0011] At the same time, the space requirement for the air conditioning system according to the invention is correspondingly small. The use of carbon dioxide as the secondary fluid allows the hoses to be made significantly smaller. In particular, the hoses can have a diameter reduced by approximately 50% compared to hoses for water-glycol mixtures. This saves space in the vehicle and also reduces the material required for manufacturing the hoses.

[0012] In a preferred embodiment of the air conditioning system according to the invention, the refrigerant of the compressor circuit differs from the refrigerant of the radiator circuit and / or the air conditioning circuit. This allows the various circuits to be operated with particular energy efficiency, as the refrigerant suitable for the respective purpose of each circuit can be used.

[0013] In particular, the refrigerant in the compressor circuit can include a flammable refrigerant. The flammable refrigerant can be propane, especially R290. The compressor circuit is preferably equipped with a very small refrigerant volume. The compressor circuit thus only provides the corresponding heat or cooling energy, which is absorbed via the radiator circuit and can be dissipated to a vehicle interior via the air conditioning circuit. Therefore, the compressor circuit is particularly compact and requires only a small quantity or volume of refrigerant.

[0014] The refrigerant in the compressor circuit is also referred to as the primary fluid. Since the

[0015] Since the volume in the compressor circuit is relatively small, a flammable refrigerant can be used for this purpose.

[0016] 102316-WO - MSP Keller Schneider August 8, 2025 Patentanwalts GmbH A refrigerant with very good heat transfer performance can be used. The amount of flammable refrigerant can be so small that it is possible to use such a refrigerant within the respective vehicle standards. In particular, the operational safety of a vehicle is not impaired by the use of a flammable refrigerant in the compressor circuit, as the required amount of refrigerant is below the hazard threshold.

[0017] In the air conditioning system according to the invention, it is further preferably provided that the radiator circuit and / or the air conditioning circuit each have a refrigerant expansion tank. The refrigerant expansion tank can compensate for volume changes of the refrigerant that occur due to temperature changes. It is preferred if the refrigerant expansion tank has a volume of less than 1000 ml, in particular less than 750 ml. The refrigerant expansion tank ensures that the maximum average density specified by technical standards is maintained. Likewise, the refrigerant expansion tank ensures that the corresponding maximum values ​​for stagnation pressures are maintained.

[0018] In a preferred embodiment of the invention, the radiator circuit includes a cooler, in particular an air cooler. The refrigerant circulating in the radiator circuit can be cooled via the cooler in order to be subjected to renewed evaporation.

[0019] The air conditioning circuit preferably includes an air conditioning heat exchanger. The air conditioning heat exchanger can, in particular, be located in or near the interior of a vehicle to transfer heat or cold from the air conditioning circuit to an airflow that regulates the temperature of the vehicle interior.

[0020] It is preferably provided that the refrigerant charge in the radiator circuit and / or the air conditioning circuit is between 200 kg / m³. 3 and 300 kg / m² 3 is set. This ensures that at maximum

[0021] 102316-WO - MSP Keller Schneider August 8, 2025 Patentanwalts GmbH The ambient temperature must not exceed the maximum pressure in the respective circuit. This improves the safety of the air conditioning system. A radiator pump can be located in the radiator circuit and an air conditioning pump in the air conditioning circuit. The radiator pump and / or the air conditioning pump are preferably adapted so that the differential pressure of the circulating refrigerant, especially carbon dioxide, is limited to less than 5 bar. This protects the hydraulic components of the air conditioning system.

[0022] It is also possible for the radiator circuit and the air conditioning circuit to be connected via several diverter valves, in particular 3-way valves, so that the air conditioning system can be operated alternately in cooling and heating modes. The diverter valves thus allow switching between heating and cooling modes. This is particularly useful in mobile applications where switching may need to be done quickly to accommodate different climatic or weather conditions.

[0023] Specifically, a first changeover valve, a second changeover valve, a third changeover valve, and a fourth changeover valve can be provided, wherein the changeover valves are arranged and configured such that the cooler is fluid-connected to the radiator pump in cooling mode and to the second heat exchanger in heating mode via the first changeover valve, and / or the first heat exchanger is fluid-connected to the cooler in cooling mode and to an air conditioning heat exchanger in heating mode via the second changeover valve, and / or the air conditioning pump is fluid-connected to the air conditioning heat exchanger in cooling mode and to the cooler in heating mode via the third changeover valve, and / or

[0024] 102316-WO - MSP Keller Schneider August 8, 2025 Patentanwalts GmbH the air conditioning heat exchanger is fluidly connected via the fourth switching valve in cooling mode to the second heat exchanger and in heating mode to the radiator pump.

[0025] A subordinate aspect of the invention relates to a vehicle, in particular a battery-electric or hybrid-electric, multi-track vehicle, with a previously described air conditioning system.

[0026] The invention is explained in more detail below using an exemplary embodiment with reference to the accompanying schematic drawings. These show

[0027] Fig. 1 shows a circuit diagram of an air conditioning system according to the invention in a preferred embodiment; and

[0028] Fig. 2 shows a circuit diagram of an air conditioning system according to the invention in a further embodiment, wherein switching valves are provided for switching between a heating operation and a cooling operation.

[0029] The air conditioning system generally comprises a radiator circuit 10, an air conditioning circuit 20, and a compressor circuit 30. The compressor circuit 30 is connected to both the radiator circuit 10 and the air conditioning circuit 20 via heat transfer. Specifically, the compressor circuit 30 has a first heat exchanger 31, which is connected to the radiator circuit 10. Furthermore, a second heat exchanger 32 is provided in the compressor circuit 30, which is connected to the air conditioning circuit 20.

[0030] The compressor circuit 30 further comprises a compressor 34 and an expansion valve 33. Essentially, the compressor circuit 30 forms a heat pump for generating heat. However, the compressor circuit 30 can also be used to generate cooling. For this purpose, a suitable refrigerant, preferably comprising propane, in particular R290, circulates in the compressor circuit 30.

[0031] The radiator circuit 10 includes a radiator pump 14, which ensures the circulation of a refrigerant within the radiator circuit 10. Furthermore, the radiator circuit 10 contains a

[0032] 102316-WO - MSP Keller Schneider August 8, 2025 Patent Attorneys GmbH A refrigerant expansion tank 11 is provided. The refrigerant expansion tank 11 compensates for volume changes in the refrigerant that can occur due to temperature fluctuations. The refrigerant in the radiator circuit 10 also flows through a cooler 12, which is preferably located in the engine compartment of a vehicle. The cooler 12 is essentially formed by a heat exchanger through which air can flow. During vehicle movement, the air is automatically guided through the cooler 12. Should the airflow be insufficient for adequate cooling, a fan 13 is also provided to transport air through the cooler 12.

[0033] The air conditioning circuit 20 comprises an air conditioning pump 24, through which the refrigerant circulates within the air conditioning circuit 20. The air conditioning pump 24 pumps the refrigerant of the air conditioning circuit 20 through an air conditioning heat exchanger 22, which is located in an air duct 40 or air duct system of a vehicle interior. Air is blown into the vehicle interior via the air duct 40, which may have several branches. A blower 23 is provided for this purpose. The air conveyed by the blower 23 passes through the air conditioning heat exchanger 22 and absorbs the corresponding heat or cold there, so that the vehicle interior can be air-conditioned accordingly. The air conditioning circuit 20 also includes a refrigerant expansion tank 21, which compensates for any volume changes of the refrigerant within the air conditioning circuit 20.

[0034] Different refrigerants can circulate in the individual circuits, i.e., in the radiator circuit 10, the air conditioning circuit 20, and the compressor circuit 30. Various configurations are conceivable.

[0035] On the one hand, the radiator circuit can be designed to use carbon dioxide, specifically R744, as the refrigerant. The refrigerant lines can then be correspondingly smaller. Compared to other refrigerants, especially water-glycol mixtures, this results in a significant space saving. Furthermore, the use of R744 reduces the pumping work of the radiator pump 14. This allows the pump to be smaller and more energy-efficient.

[0036] 102316-WO - MSP Keller Schneider, August 8, 2025, Patentanwalts GmbH. The air conditioning circuit 20, however, can be operated with a flammable refrigerant, in particular propane or R290.

[0037] In an alternative configuration, the radiator circuit 10 can be operated with a flammable refrigerant, for example propane or R290. The air conditioning circuit 20, on the other hand, can be operated with carbon dioxide or R744 as the refrigerant. This configuration is particularly useful if, for regulatory or safety reasons, a flammable refrigerant cannot be used in the air conditioning circuit 20.

[0038] A particularly advantageous variant is one in which both the radiator circuit 10 and the air conditioning circuit 20 use carbon dioxide or R744 as the refrigerant. This allows for a very compact design of both the radiator circuit 10 and the air conditioning circuit 20, and increases the overall system's energy efficiency because the radiator pump 14 and the air conditioning pump 24 can be designed with higher energy efficiency. The improved energy efficiency of the radiator pump 14 and the air conditioning pump 24 results from the fact that the pumping work is significantly reduced when using carbon dioxide as the refrigerant compared to water-glycol mixtures or propane or R290.

[0039] In all cases, it is preferred that the compressor circuit 30 contains a flammable refrigerant, in particular propane or R290. The compressor circuit 30 is designed to be particularly small and compact, thus limiting the amount of flammable refrigerant. The refrigerant quantity in the compressor circuit 30 is chosen to be so low that it poses no relevant safety risk in a mobile application, especially in a vehicle. The compressor circuit 30 can therefore be operated with particularly high thermal efficiency. The power consumption of the compressor 34 can also be kept low, especially compared to a compressor 34 suitable for carbon dioxide.

[0040] Fig. 2 shows an alternative or further developed embodiment of the air conditioning system according to the invention. The air conditioning system according to Fig. 2

[0041] 102316-WO - MSP Keller Schneider, August 8, 2025, Patentanwalts GmbH, corresponds with its essential components to the air conditioning system according to Fig. 1. In particular, a radiator circuit 10, an air conditioning circuit 20, and a compressor circuit 30 are present. The individual circuits have the same components as in the embodiment according to Fig. 1.

[0042] The embodiment shown in Fig. 2 differs from the embodiment shown in Fig. 1 in that several switching valves 15, 16, 25, 26 are provided to redirect the refrigerant flows so that the air conditioning system can be switched from heating to cooling mode. Another difference from the embodiment shown in Fig. 1 is that, advantageously, the radiator circuit 10 and the air conditioning circuit 20 use carbon dioxide and R744, respectively, as refrigerants. This is advantageous, particularly for the switching valves 15, 16, 25, 26, in order to use identical components.

[0043] In heating mode, the changeover valves 15, 16, 25, and 26 are configured so that the refrigerant in the radiator circuit is circulated by the air conditioning pump 24. From the air conditioning pump 24, the refrigerant flows via the third changeover valve 25 to the radiator 12. The refrigerant then passes through the first changeover valve 15 to the second heat exchanger 32. In heating mode, the refrigerant in the air conditioning circuit 20 is circulated by the radiator pump 14. From the radiator pump 14, the refrigerant enters the first heat exchanger 31 and is then routed via the second changeover valve 16 to the air conditioning heat exchanger 22. There, the refrigerant transfers its heat to the air flowing through the air duct 40, thus heating the vehicle interior. The cooled refrigerant flows from the air conditioning heat exchanger 22 via the fourth switching valve 26 back to the radiator pump 14.

[0044] For cooling operation, the switching valves 15, 16, 25, 26 are switched accordingly, resulting in refrigerant flows as, for example, those fixed in the embodiment shown in Fig. 1. Specifically, the refrigerant in the radiator circuit is pumped through the first heat exchanger 31 by the radiator pump 14 and then directed to the cooler 12 via the second switching valve 16. From the cooler 12, the

[0045] 102316-WO - MSP Keller Schneider August 8, 2025 Patent Attorneys GmbH Refrigerant from radiator circuit 10 returns to radiator pump 14 via the first switching valve 15. In air conditioning circuit 20, the third switching valve 25 is positioned so that, starting from air conditioning pump 24, the refrigerant from air conditioning circuit 20 flows directly to the air conditioning heat exchanger 22. From there, the heated refrigerant passes through the fourth switching valve 26 to the second heat exchanger 32. After passing through the second heat exchanger 32, the refrigerant from air conditioning circuit 20 is pumped back to air conditioning pump 24.

[0046] 102316-WO - MSP Keller Schneider August 8, 2025 Patent Attorneys GmbH Reference List

[0047] 10 Radiator circuit

[0048] 11 Refrigerant expansion tanks of the radiator circuit

[0049] 12 coolers

[0050] 13 Fan

[0051] 14 Radiator pump

[0052] 15 first switching valve

[0053] 16 second switching valve

[0054] 20 Air conditioning cycle

[0055] 21 Refrigerant expansion tanks of the air conditioning circuit

[0056] 22 air conditioning heat exchangers

[0057] 23 blowers

[0058] 24 air conditioning pump

[0059] 25 third switching valve

[0060] 26 fourth switching valve

[0061] 30 Compressor circuit

[0062] 31 first heat exchanger

[0063] 32 second heat exchanger

[0064] 33 Expansion valve

[0065] 34 Compressor

[0066] 40 air duct

[0067] 102316-WO - MSP Keller Schneider August 8, 2025 Patent Attorneys GmbH

Claims

Patent claims 1. Air conditioning system for a vehicle, in particular a battery-electric or hybrid-electric multi-track vehicle, comprising a radiator circuit (10), an air conditioning circuit (20) and a compressor circuit (30), in each of which a refrigerant circulates, wherein the compressor circuit (30) is coupled to the radiator circuit (10) via a first heat exchanger (31) and to the air conditioning circuit (20) via a second heat exchanger (32) for temperature transfer, and wherein the refrigerant of the radiator circuit (10) and / or the air conditioning circuit (20) comprises carbon dioxide, in particular R744.

2. Air conditioning system according to claim 1 characterized in that the refrigerant of the compressor circuit (30) differs from the refrigerant of the radiator circuit (10) and / or the air conditioning circuit (20).

3. Air conditioning system according to claim 1 or 2 characterized in that the refrigerant of the compressor circuit (30) comprises a flammable refrigerant, in particular R290.

4. Air conditioning system according to one of the preceding claims characterized in that the radiator circuit (10) and / or the air conditioning circuit (20) each have a refrigerant expansion tank (11, 21).

5. Air conditioning system according to claim 4 characterized in that the refrigerant expansion tank (11, 21) has a volume of less than 1000 ml, in particular less than 750 ml. 102316-WO - MSP Keller Schneider August 8, 2025 Patentanwalts GmbH 6. Air conditioning system according to one of the preceding claims characterized in that the radiator circuit (10) has a cooler (12), in particular an air cooler.

7. Air conditioning system according to one of the preceding claims characterized in that the air conditioning circuit (20) has an air conditioning heat exchanger (22).

8. Air conditioning system according to one of the preceding claims, characterized in that the refrigerant charge in the radiator circuit (10) and / or in the air conditioning circuit (20) is between 200 kg / m³. 3 and 300 kg / m² 3 has been set.

9. Air conditioning system according to one of the preceding claims characterized in that a radiator pump (14) is arranged in the radiator circuit (10) and an air conditioning pump (24) is arranged in the air conditioning circuit (20), wherein the radiator pump (14) and / or the air conditioning pump (24) is adapted such that a differential pressure of the refrigerant flowing around, in particular carbon dioxide, is limited to less than 5 bar.

10. Air conditioning system according to one of the preceding claims characterized in that the radiator circuit (10) and the air conditioning circuit (20) are connected via several switching valves (15, 16, 25, 26), in particular 3-2-way valves, such that the air conditioning system can be operated selectively in a cooling mode or a heating mode.

11. Air conditioning system according to claim 10 characterized by a first switching valve (15), a second switching valve (16), a third switching valve (25) and a fourth switching valve (26), wherein the switching valves (15, 16, 25, 26) are arranged and configured such that 102316-WO - MSP Keller Schneider August 8, 2025 Patentanwalts GmbH the cooler (12) is fluid-connected to the radiator pump (14) in cooling mode and to the second heat exchanger (32) in heating mode via the first switching valve (15), and / or the first heat exchanger (31) is fluid-connected to the cooler (12) in cooling mode and to an air conditioning heat exchanger in heating mode via the second switching valve (16). (22) is fluid-connected, and / or the air conditioning pump (24) is fluid-connected via the third switching valve (25) to the air conditioning heat exchanger (22) in cooling mode and to the radiator (12) in heating mode, and / or - the air conditioning heat exchanger (22) is fluid-connected via the fourth switching valve (26) in The cooling operation is fluid-connected to the second heat exchanger (32) and the heating operation is fluid-connected to the radiator pump (14).

12. Vehicle, in particular a battery-electric or hybrid-electric, multi-track vehicle, with an air conditioning system according to one of the preceding claims. 102316-WO - MSP Keller Schneider August 8, 2025 Patent Attorneys GmbH

Images