Cooling system for a vehicle, axle assembly, vehicle and process

Abstract

A cooling system (10) is provided for a vehicle, in particular an electric vehicle or a hybrid vehicle, comprising: a heat pump (11) with an evaporator and a condenser, a first cooling circuit (K1) associated with the evaporator, a second cooling circuit (K2) associated with the condenser, and a balancing device (12) configured to exchange thermal energy between the first cooling circuit (K1) and the second cooling circuit (K2).

Description

[0001] The present invention relates to a cooling system for a vehicle, in particular for an electric vehicle or a hybrid vehicle, an axle assembly and a vehicle with such a cooling system and a method for cooling components of a vehicle.

[0002] Vehicles, particularly electric vehicles and hybrid vehicles, require a cooling system to dissipate the power losses that arise in various units, such as a battery, an electric motor, and other electronic components such as an inverter, a DC / DC converter, a DC / AC converter, and the like, during operation and charging. Vehicle systems typically have multiple cooling circuits to form a controlled thermal management system. Typically, a coolant circuit with a water-glycol-based coolant is present, through which heat from the individual components can be dissipated to the environment. Another cooling circuit includes a heat pump or AC compressor for air conditioning a passenger compartment or for assisting in heat dissipation from the components. A third cooling circuit is provided in some systems to dissipate heat from the transmission's lubrication and cooling oil system.

[0003] In existing systems, two basic principles prevail for interior air conditioning and the cooling of power electronics. According to the first principle, the passenger compartment is heated by means of a coolant heat exchanger from the cooling circuit of the electrical machine, for example an electric drive, and cooled via the cooling circuit of the air conditioning system or heat pump. Therefore, additional heat exchangers are required for interior air conditioning. For greater heating output, additional electric heaters are usually provided, which directly heat either the coolant or the interior air. According to a second principle, the heating and cooling functions are bundled via the cooling circuit, in which a condenser heat exchanger is used. Depending on requirements, the air is either heated by the condenser heat exchanger or cooled by an evaporator heat exchanger.

[0004] What all systems have in common is that the power electronics are connected in series with the electric machine in terms of cooling, whereby the coolant preheated by the power electronics is still sufficient for cooling the electric machine.

[0005] The energy storage system also experiences losses during energy conversion due to the chemical and physical processes within it. Their impact on heat generation depends on the power, meaning that at low power levels, the power loss is also low. However, the greater the energy conversion, the higher the internal losses. Therefore, liquid cooling is found in most systems.

[0006] It is well known that heat pumps are used in cooling systems. The heat pump has a defined performance range. This performance range depends on various boundary conditions, such as the flow temperatures at the evaporator and condenser, the compressor speed, the position of the expansion valve, etc. The performance range includes a cooling capacity P K between P K > P min and P K < P max . The system's heat pump therefore has a lower limit power P min If the minimum required heat load on the evaporator is not met, the target temperature of the water-side evaporator outlet can no longer be maintained in a low-temperature circuit or at the evaporator inlet. As a result, the actual temperature falls below the target.

[0007] To compensate for this situation and enable the heat pump to operate, it is possible to shut down the compressor and intermittently switch the temperature control on and off using a two-point control strategy. This results in greater mechanical stress on the components during startup, thus reducing the service life of the heat pump. Furthermore, efficiency is significantly reduced.

[0008] Therefore, it is an object of the present invention to provide a cooling system that enables more efficient operation of a heat pump.

[0009] This problem is solved by a cooling system having the features of claim 1, by an axle assembly having the features of claim 8, by a vehicle having the features of claim 9 and by a method for cooling components of a vehicle having the features of claim 10.

[0010] According to one aspect of the present invention, a cooling system for a vehicle is provided, in particular an electric vehicle, a hybrid vehicle, or a vehicle with a hydrogen-based drive, for example, a fuel cell. The vehicle comprises a heat pump with an evaporator and a condenser, a first cooling circuit associated with the evaporator, a second cooling circuit associated with the condenser, and a compensating device configured to exchange thermal energy between the first cooling circuit and the second cooling circuit.

[0011] Compared to the known prior art, the present invention offers the advantage that the energy losses from electrical components and the energy from cooling a passenger compartment (FGZ) can be transported to where they are useful. Only when the requirements are met and the storage capacities are exhausted is energy dissipated into the environment. The basic idea of ​​the proposed cooling system according to one aspect of the present invention is based on the representation of two coolant circuits as so-called main cooling circuits, consisting of the first cooling circuit, which can be a low-temperature circuit (NT), for example, and the second cooling circuit, which can be a high-temperature circuit (HT), for example. In other words, the first cooling circuit and the second cooling circuit can have different temperature levels. Furthermore, in one embodiment, the cooling system can have valves orhave a valve arrangement that allows different connections of some components, optionally with the first cooling circuit or the second cooling circuit. Furthermore, the valve arrangement can provide a single-circuit circuit that supplies all components in series, whereby the order of different components relative to one another remains unchanged, or optionally a dual-circuit circuit can be provided. The thermal coupling between the first cooling circuit and the second cooling circuit can be achieved by a heat pump.

[0012] According to one aspect of the present invention, the heat pump comprises its own closed circuit. The heat pump is thermally coupled to the first cooling circuit and the second cooling circuit, or connected in such a way that thermal energy can be at least partially transferred.

[0013] According to one aspect of the present invention, the heat pump comprises an evaporator for evaporating a refrigerant. The heat pump further comprises a condenser for liquefiing the refrigerant again. The condenser can also be referred to as a condenser. The heat pump can have a compressor that compresses a refrigerant, such as propane (R-290), carbon dioxide (R-744), or R-1234yf. The compressed refrigerant can be cooled in a downstream condenser or condenser. This allows thermal energy to be extracted from the refrigerant in the form of heat. This heat can be transferred to the second cooling circuit. Downstream of the condenser, at least one expansion valve is provided in the heat pump, which expands the liquefied refrigerant and reduces the pressure. This causes the temperature of the refrigerant in the heat pump to drop further. In a downstream heat exchanger orThe evaporator absorbs heat energy, which cools the first cooling circuit. From there, the cycle can be repeated in the heat pump, starting with the compressor. In other words, the first cooling circuit and the second cooling circuit can both exchange thermal energy with the heat pump.

[0014] According to one aspect of the present invention, the first cooling circuit is assigned to the evaporator of the heat pump. This means that the first cooling circuit is thermally coupled to the evaporator. In other words, the evaporator is arranged in the first cooling circuit or is operated in the first cooling circuit. More specifically, thermal energy is preferably transferred from the first cooling circuit to the evaporator. The transferred thermal energy of the first cooling circuit can convert a refrigerant in the evaporator into a gaseous state. The first cooling circuit is thermally coupled to the evaporator directly or indirectly.

[0015] According to one aspect of the present invention, the second cooling circuit is assigned to the condenser of the heat pump. This means that the second cooling circuit is thermally coupled to the condenser. In other words, the condenser is arranged in the second cooling circuit or is operated in the second cooling circuit. More specifically, thermal energy is preferably transferred from the condenser to the second cooling circuit. The thermal energy transferred to the second cooling circuit can convert a refrigerant in the condenser into a liquid state. The second cooling circuit is thermally coupled to the condenser directly or indirectly.

[0016] The equalizing device can be arranged downstream or upstream of the heat pump in a coolant flow direction. The equalizing device is simultaneously part of the first cooling circuit and the second cooling circuit. The equalizing device serves to exchange thermal energy between the first cooling circuit and the second cooling circuit. The exchange of thermal energy can occur in both directions.

[0017] A refrigerant is characterized by its use in a thermodynamic cycle (heat pump) to cool a medium below ambient temperature. A coolant is used in a refrigeration cycle to transfer the enthalpy (heat energy) along the temperature gradient to a heat sink. Ambient air, for example, is a suitable heat sink. The coolant can also be referred to as a heat transfer medium, heating medium, or coolant.

[0018] The first cooling system and the second cooling system preferably each have an identical coolant. The coolant can comprise a water-glycol mixture, an alcohol, an oil, and / or ammonia (NH3). The refrigerant or cooling fluid can be in a liquid or gaseous state.

[0019] The balancing device makes it possible to provide the evaporator with thermal energy corresponding to a minimum operating value of the evaporator. The operating value of the evaporator is defined by a predefined cooling capacity required for uninterrupted operation of the heat pump. The predefined cooling capacity can therefore also be referred to as the minimum cooling capacity. In other words, the balancing device is intended or configured to prevent reduced performance of the heat pump by thermally coupling the first cooling circuit with the second cooling circuit. Reduced performance occurs when the minimum cooling capacity required for operation of the heat pump is not achieved. Cooling capacity is the amount of heat that the device can remove per unit of time – in other words, the amount of cold delivered per unit of time.The cooling capacity thus describes how much heat the heat pump absorbs from the first cooling circuit. More precisely, the cooling capacity describes how much heat energy is transferred from the first cooling circuit to the evaporator.

[0020] In one aspect of the present invention, the temperature of the first coolant of the first cooling circuit is at least partially adjusted to the temperature of the second coolant of the second cooling circuit using the compensation device, which thermally couples the first cooling circuit and the second cooling circuit to one another at least in sections. As a result, a specific / predefined cooling capacity is maintained at the evaporator of the heat pump or a minimum cooling capacity is maintained at the evaporator of the heat pump. If the minimum cooling capacity is not reached, the heat pump cannot be operated. In other words, the compensation device makes it possible to provide a minimum cooling capacity of the evaporator of the heat pump by thermally coupling the first cooling circuit with the second cooling circuit.This creates a kind of thermal short circuit that compensates for the power difference between the minimum cooling capacity and the cooling capacity requirement. The minimum cooling capacity of the heat pump can be between 700 and 1500 W, preferably 1000 W.

[0021] Preferably, the first cooling circuit and the second cooling circuit have different temperature levels, wherein the first cooling circuit in particular comprises a low-temperature circuit and the second cooling circuit comprises a high-temperature circuit. This means that in the flow of the heat pump, the first cooling circuit has a lower temperature than the second cooling circuit. The high-temperature circuit can have a coolant with a temperature in a range of 35 to 95°C. The low-temperature circuit can have a coolant with a temperature in a range of -30 to 45°C. The aforementioned temperatures refer to the "normal" operating state. Different temperatures may exist when the system is started.Preferably, the low-temperature circuit is provided for cooling an energy storage device, in particular a battery, and the high-temperature circuit is provided for cooling an electrical machine and / or power electronics. A different arrangement of the components in the cooling circuit is also conceivable.

[0022] In one embodiment, the compensating device comprises a mixing valve, in particular a multi-way valve, and / or a heat exchanger, in particular a water-water heat exchanger. The mixing valve is designed to at least partially mix a coolant of the first cooling circuit and a coolant of the second cooling circuit. By mixing the coolant, the energy level in the first circuit (NT) is increased and in the second circuit (HT) is reduced, i.e. it can be said that thermal energy is transferred, in particular directly, from the second cooling circuit to the first cooling circuit or vice versa. The heat exchanger enables an indirect transfer of thermal energy from the second cooling circuit to the first cooling circuit or vice versa.

[0023] In one embodiment, an energy storage device is arranged in the first cooling circuit, and an electric motor is arranged in the second cooling circuit. This arrangement allows the power loss from the electric motor to be transferred to the first cooling circuit in the form of thermal energy. In other words, a coolant can be heated in the drive unit, in particular by waste heat from the drive unit. The resulting power loss can thus be used to enable efficient operation of the heat pump's evaporator.

[0024] In one embodiment, the equalizing device is arranged upstream of the heat pump in a coolant flow direction. Preferably, the equalizing device is arranged upstream of the heat pump in a coolant flow direction. This means that preferably no further component is arranged in the first and second cooling circuits between the heat pump and the equalizing device. This allows the thermal energy downstream of the equalizing device to be transferred to the heat pump's evaporator without loss.

[0025] In one embodiment, at least one flow element, in particular an orifice plate and / or throttle, for regulating a volume flow of the coolant is arranged upstream of the compensating device in a flow direction of a coolant. In particular, the at least one flow element is adjustable. This can be achieved, for example, by an adjustable orifice plate or throttle. This enables active control of a volume flow of a coolant in the first and second cooling circuits. More precisely, the volume flow can be adjusted by the at least one adjustable flow element such that the evaporator is provided with thermal energy that corresponds to a minimum operating value of the evaporator.

[0026] In one embodiment, the compensating device is arranged downstream of a radiator and an energy storage device in the flow direction of a coolant. Such an arrangement of the compensating device does not reduce the flow temperature at the radiator and, consequently, does not affect the maximum system cooling capacity of the cooling system.

[0027] In a further embodiment, the first cooling circuit comprises a first bypass circuit, wherein the compensating device is provided in the first bypass circuit. In a further embodiment, the second cooling circuit comprises a second bypass circuit, wherein the compensating device is provided in the second bypass circuit. Preferably, the first cooling circuit and the second cooling circuit are thermally coupled to one another via the compensating device in the first bypass circuit and in the second bypass circuit, or are connected to one another for transferring thermal energy. The first bypass circuit preferably circulates around an energy storage device or runs parallel to an energy storage device, and the second bypass circuit preferably circulates around a radiator or runs parallel to a radiator.

[0028] In a further embodiment, the compensating device is arranged upstream of a first pump of the first cooling circuit and upstream of a second pump of the second cooling circuit.

[0029] In a further embodiment, the compensating device is arranged upstream of an energy storage device in the first cooling circuit, in the flow direction of a coolant, and downstream of a radiator in the second cooling circuit. Such an arrangement of the compensating device does not reduce the flow temperature at the radiator and does not affect the maximum system cooling capacity. Furthermore, the temperature in the flow direction of a coolant upstream of the energy storage device in the first cooling circuit is sufficient for cooling the energy storage device after an exchange of thermal energy by the compensating device.

[0030] In one embodiment, the compensating device is configured to control the first cooling circuit and the second cooling circuit in such a way that switching between a single-circuit circuit and a dual-circuit circuit is possible. In a single-circuit circuit, the different components are arranged in series in the flow direction of a coolant in the cooling circuit. In a dual-circuit circuit, the different components are arranged parallel to one another in the flow direction of a coolant in the cooling circuit, at least in sections. The single-circuit circuit represents a simple way of increasing the heat load on the evaporator. Here, a return flow from the second cooling circuit is fed directly to the evaporator, which strictly speaking corresponds to at least partial, in particular complete, mixing of the coolant of the first cooling circuit and the second cooling circuit.The aforementioned dual-circuit configuration allows for several options for coupling the first cooling circuit and the second cooling circuit for the exchange of thermal energy. Alternatively or additionally, additional switching elements or valves can be arranged in the first and second cooling circuits for the purpose of switching the lines.

[0031] According to a further aspect of the present invention, an axle assembly is provided comprising a cooling system according to one of the above-mentioned embodiments, power electronics, in particular an inverter, and an electric machine. It is further possible for the axle assembly to include a parking lock and / or a transmission.

[0032] According to a further aspect of the present invention, a vehicle is provided with a cooling system according to an above-mentioned embodiment or an axle assembly according to the preceding embodiment. The vehicle is preferably an electric vehicle. Alternatively, a hybrid vehicle or a vehicle with a hydrogen-based drive is possible.

[0033] According to a further aspect of the present invention, a method for cooling components of a vehicle is provided. The method comprises operating an evaporator in a first cooling circuit, operating a condenser in a second cooling circuit, and exchanging thermal energy between the first cooling circuit and the second cooling circuit, in particular to provide the evaporator with thermal energy that corresponds to a minimum operating value of the evaporator or to maintain a minimum cooling capacity of the evaporator.

[0034] In the method, the temperature of the first coolant of the first cooling circuit is at least partially adjusted to the temperature of the second coolant of the second cooling circuit using the compensation device, which thermally couples the first cooling circuit and the second cooling circuit to one another at least in sections. This enables the provision of a predefined or minimum cooling capacity of the heat pump's evaporator.

[0035] In one embodiment of the present invention, a thermal coupling between the first cooling circuit (low-temperature circuit) and the second cooling circuit (high-temperature circuit) is proposed to increase the heat load at the evaporator. Particularly when the heat load in the first cooling circuit is lower than the lowest possible cooling capacity of the heat pump, heat exchange between the first cooling circuit and the second cooling circuit can enable an increase in the flow temperature at the heat pump's evaporator. This increases the cooling capacity requirement, thus avoiding shutdown of the compressor or intermittent operation of the heat pump.

[0036] The advantage of this is that the flow temperature difference at the water inlet is reduced, thus increasing thermal efficiency and minimizing overall losses. It should be noted that at least part of the transferred heat was previously transferred to the second cooling circuit using electrical power.

[0037] The arrangement of the compensating device is essentially arbitrary. However, it is advantageous to place the compensating device downstream of a radiator to avoid affecting the maximum system cooling capacity by not reducing the flow temperature at the radiator.

[0038] It is advantageous if, for the reduced-capacity control of the heat pump, the heat exchanger is located directly upstream of the condenser and the evaporator, or upstream of the first and / or second pump, particularly if the heat pump is located upstream of the pumps. The term "reduced-capacity control" refers to the fact that the flow temperature of a coolant upstream of the heat pump's evaporator is regulated by the compensation device through the exchange of thermal energy between the first and second cooling circuits in such a way that a minimum cooling capacity of the evaporator can be provided.

[0039] For the reduced-power control of the heat pump, i.e., maintaining the minimum cooling capacity or minimum operating value, the required thermal power is relatively low. Therefore, it is advantageous to use the supply lines of components with different temperature levels, e.g., from the low-temperature circuit (first cooling circuit) and the high-temperature circuit (second cooling circuit), as heat exchangers. For example, a defined contact surface is provided in close proximity, through which energy is transferred from the higher-temperature coolant to the lower-temperature coolant.

[0040] In a particularly advantageous embodiment, the coolant flows in the first cooling circuit and in the second cooling circuit are conducted in a pipe-in-pipe system, fluidically separated, with the thermal coupling being provided via a surface of the inner pipe. Preferably, an inner pipe is connected to the first cooling circuit with a lower temperature, while the second cooling circuit with a higher temperature is connected to an annular duct or an outer pipe. This offers the advantage that the environment has no additional influence on the flow temperature, while energy is released via the surface of the outer pipe to the outside air, which generally has a lower temperature, and as a result the flow temperature for the components integrated downstream in the second cooling circuit, e.g. an electrical machine, is lower, thereby increasing the cooling performance potential.

[0041] If the layout of the circuits has a separate supply for the power electronics, in particular an inverter, for example by integration into the first cooling circuit, and the electrical machine, for example by integration into the second cooling circuit, then their supply lines are particularly suitable for a pipe-in-pipe system, especially if the thermal management system is installed relatively far away from the power electronics and the electrical machine.

[0042] The heat exchange can be regulated or dependent on the physical parameters, e.g. volume flow and temperature difference of the cooling fluid. It is possible to use additional valves for this purpose, or to vary the volume flow of the coolant and thus the heat output at the heat exchanger by combining flow elements, such as orifices and throttles. A bypass path on the water-water heat exchanger (WWHE) is particularly useful, as it enables volume flow branching or volume flow limitation through the WWHE by defining the flow resistance between the WWHE and the bypass, e.g. using orifices or a modified cross-section. By using at least one orifice, a pressure relief valve or another valve that can be actively adjusted, the output of the WWHE can be regulated as required.If the WWWT is arranged upstream of the first pump and / or the second pump, the active control can be used to particularly advantageously vary or limit the suction pressure in order to, for example, minimize cavitation effects at high volume flows.

[0043] In a further variant, the energy exchange is achieved by mixing the fluids from the first cooling circuit (low-temperature circuit) and the second cooling circuit (high-temperature circuit) in proportion to the desired target temperature. Equal volume fractions are transferred from the low-temperature circuit to the high-temperature circuit and from the high-temperature circuit to the low-temperature circuit. The mixing temperature is adjusted in proportion to the exchanged water volumes according to the respective temperature difference. A combination of a mixing valve and a flow control valve is practical and technically simple, so that preferably any valve present in the system for flow control can also be designed as a mixing valve.The ratio of the mixture should preferably be adjusted so that the amount of energy exchanged per unit of time corresponds at least to the difference between the cooling capacity requirement and the minimum capacity of the heat pump.

[0044] The arrangement of the mixing valve downstream of a heat exchanger for the passenger compartments and upstream of an energy storage device has proven particularly advantageous, whereby the air conditioning function is ensured by a deliberately low flow temperature and at the same time the energy storage device can be tempered within a narrow tolerance band by adjusting a correspondingly desired flow temperature by mixing.

[0045] The mixing function can also be useful in a single-circuit system for regulating the temperature of the energy storage system. The mixing valve can be designed as a four-way valve with at least three or more positions, with the two end positions representing either a connection of the ports without mixing or very little mixing. The intermediate position can be designed according to the required mixing depending on the application, with the proportions being freely adjustable. Continuous adjustment of the mixing valve is possible with a customized control system.

[0046] Individual features or embodiments of the present invention can be combined with other features or other embodiments to form new embodiments. Advantages and developments mentioned for the features or embodiments also apply analogously to the new embodiments. Developments and advantages mentioned in connection with the device also apply analogously to the method, and vice versa.

[0047] Advantageous embodiments of the invention are described in detail below with reference to the attached figures: Fig. 1 is a schematic view of a cooling system according to an embodiment of the present invention. Fig. 2 is a schematic view of a cooling system according to an embodiment of the present invention. Fig. 3 is a schematic view of a cooling system according to an embodiment of the present invention. Fig. 4 is a schematic view of a cooling system according to an embodiment of the present invention. Fig. 5 is a schematic view of a cooling system according to an embodiment of the present invention. Fig. 6 is a schematic view of a cooling system according to an embodiment of the present invention. Fig. 7 is a schematic view of a cooling system according to an embodiment of the present invention. Fig. 8 is a schematic view of a cooling system according to an embodiment of the present invention. Fig. 9 is a schematic view of a cooling system according to an embodiment of the present invention. Fig. 10 is a schematic view of a cooling system according to an embodiment of the present invention. Fig. 11 is a schematic view of a cooling system according to an embodiment of the present invention.

[0048] Fig. 1 shows a cooling system 10 with a first cooling circuit K1 and a second cooling circuit K2. The first cooling circuit K1 is a low-temperature circuit, and the second cooling circuit K2 is a high-temperature circuit. This means that there is a temperature difference between a coolant in the first cooling circuit K1 and a coolant in the second cooling circuit K2, with the temperature in the second cooling circuit K2 being higher. The high-temperature circuit can have a coolant with a temperature in a range of 35 to 95°C. The low-temperature circuit can have a coolant with a temperature in a range of -30 to 45°C. The aforementioned temperatures refer to the "normal" operating state. Different temperatures may exist when the system is started.

[0049] Cooling circuit K1 comprises a first pump P1, and the second cooling circuit K2 comprises a second pump P2. The two pumps P1 and P2 are designed to stimulate the circulation of a coolant in the first cooling circuit K1 and the second coolant circuit K2.

[0050] A heat pump 11 is arranged downstream of the first pump P1. Power electronics 17 is arranged downstream of the second pump P2. An electric machine 14 is arranged directly downstream of the power electronics 17. The power electronics 17 and the electric machine 14 are each cooled by the second cooling circuit K2. Downstream of the electric machine 14, the heat pump 11 is arranged in the second cooling circuit K2.

[0051] The heat pump 11 comprises an evaporator for evaporating a refrigerant. The heat pump 11 further comprises a condenser for re-condensing the refrigerant. The condenser can also be referred to as a condenser. The heat pump 11 enables the exchange of thermal energy between the first and second cooling circuits K1, K2.

[0052] The first cooling circuit K1 is assigned to the evaporator of the heat pump 11. In other words, thermal energy is transferred to the evaporator of the heat pump 11 via the first cooling circuit. This means that the first cooling circuit K1 provides the thermal energy to convert a refrigerant of the heat pump 11 into a gaseous state in the evaporator.

[0053] The heat pump 11 preferably comprises a compressor. The compressor is preferably arranged in the flow direction of a refrigerant in the heat pump 11 between the evaporator and the condenser. The gaseous refrigerant is compressed by the preferably electrically driven compressor, heating the gaseous refrigerant.

[0054] The second cooling circuit is assigned to the condenser of the heat pump 11. In other words, thermal energy is transferred to the second cooling circuit K2 via the condenser of the heat pump 11. This means that the second cooling circuit K2 absorbs the thermal energy provided by the condenser.

[0055] Consequently, a coolant downstream of the heat pump 11 in the first cooling circuit K1 is colder than a coolant downstream of the heat pump 11 in the second cooling circuit K2. This applies in particular to a coolant of the first cooling circuit K1 and the second cooling circuit K2 immediately downstream of the heat pump 11.

[0056] Downstream of the heat pump 11, a cooling unit 18 is arranged in the first cooling circuit K1. The cooling unit 18 serves, for example, to cool a passenger compartment of a vehicle. Downstream of the heat pump 11, a heating unit 19 is arranged in the second cooling circuit K2. The heating unit 19 serves, for example, to heat a passenger compartment of a vehicle. The cooling unit 18 and the heating unit 19 can, for example, be part of an air conditioning unit of the vehicle.

[0057] Downstream of the cooling unit 18 and the heating unit 19, a first valve 20a is arranged in the first cooling circuit K1 and in the second cooling circuit K2. A second valve 20b is arranged in the first cooling circuit K1 and in the second cooling circuit K2 upstream of the first pump P1 and the second pump P2. The two valves 20a, 20b are each arranged in both cooling circuits K1, K2 to enable switching of the coolant flow. The two valves 20a, 20b each comprise four paths and can be arranged in two positions. This makes it possible to change or switch the flow of the first cooling circuit K1 and the second cooling circuit K2. The valves 20a, 20b can preferably be used to switch between a single-circuit circuit and a dual-circuit circuit. Unless otherwise stated, a dual-circuit circuit is assumed below.

[0058] Downstream of the valve 20a, a bypass valve 21 is arranged in each of the first cooling circuit K1 and the second cooling circuit K2. The bypass valve 21 in the first cooling circuit K1 is configured to direct a coolant either via an energy storage device 13 or a first bypass channel B1 with a compensating device 12. The bypass valve 21 in the second cooling circuit K2 is configured to direct a coolant either via a radiator 16 or a second bypass channel B2 with a compensating device 12. The first bypass channel B1 of the first cooling circuit K1 and the second bypass channel B2 of the second cooling circuit K2 are thermally coupled to one another via the compensating device 12. As a result, the first cooling circuit K1 and the second cooling circuit K2 are thermally coupled to one another. In other words, the compensating device 12 allows an exchange of thermal energy between the two cooling circuits K1, K2.The compensation device 12 allows thermal energy, in particular heat energy, to be transferred from the second cooling circuit K2 to the first cooling circuit K1.

[0059] The above-mentioned additional valve 20b is arranged downstream of the energy storage device 13 in the first cooling circuit K1 and downstream of the radiator 16 in the second cooling circuit K2. Downstream of the valve 20b, the first pump P1 is arranged in the first cooling circuit K1 and the second pump P2 is arranged in the second cooling circuit K2.

[0060] Fig. 2 shows a cooling system 10 which essentially corresponds to the cooling system 10 of Fig. 1. In contrast to the Fig. 1 shown cooling system 10 is in the cooling system 10 according to Fig. 2, the compensating device 12 is arranged in the first cooling circuit K1 upstream of the energy storage unit 13 and downstream of the radiator 16. This arrangement enables cooling of the energy storage unit 13 without reducing the flow temperature at the radiator, thus not affecting the maximum system cooling capacity.

[0061] Fig. 3 shows a cooling system 10 which essentially corresponds to the previously described cooling system 10 of Fig. 2. In contrast to the previously described cooling system 10, in the cooling system shown in Fig. In the cooling system 10 shown in Figure 3, the compensating device 12 is arranged directly upstream of the heat pump 11. This arrangement of the compensating device 12 is advantageous because, in this way, the power loss dissipated in the form of heat by the power electronics 17 and the electric machine 14 can be utilized by the compensating device 12 with low heat losses. In the present case, thermal energy, in particular heat energy resulting from the power loss of the power electronics 17 and / or from the electric machine 14, is transferred from the second cooling circuit K2 to the first cooling circuit K1 by the compensating device 12.

[0062] Fig. Figure 4 shows a cooling system that, except for the position of the compensating device 12, is essentially the same as the previously described cooling system. In the present embodiment, the compensating device 12 is arranged upstream of the first pump P1 and the second pump P2. More specifically, the compensating device 12 is arranged downstream of the valve 20b in the first cooling circuit K1 and upstream of the valve 20b in the second cooling circuit K2.

[0063] Fig. 5 shows the cooling system 10 according to the Fig. 4. This means that the compensating device 12 is arranged in the same position. Additionally, the second cooling circuit K2 has a branch in the region of the compensating device 12. The branch is arranged upstream of the compensating device 12. The branch is part of the second cooling circuit K2. The branch comprises two flow elements 15. The flow elements 15 comprise orifices, throttles, and / or constrictions.

[0064] In detail, the branch has a first branch in which a line of the second cooling circuit K2 is connected to the compensating device 12 and another line of the second cooling circuit K2 is connected to a first flow element 15a. A second branch is arranged downstream of the first flow element 15a. The second branch has a line connected to a second flow element 15b and another line connected to the second valve 20b. The second flow element is arranged downstream of the compensating device 12 in the flow direction of a coolant. The arrangement of the flow elements 15 allows an advantageous distribution of the volume flow of the coolant in order to enable the most optimal exchange of thermal energy through the compensating device 12.

[0065] In the Fig. 1-5, the equalizing device 12 comprises a heat exchanger. In particular, a water-to-water heat exchanger. Alternatively, other equalizing devices or heat exchangers are possible for exchanging thermal energy.

[0066] Fig. 6 shows a cooling system 10 which corresponds to the cooling system according to Fig. 5. In contrast to the previous embodiment, the present cooling system has an adjustable flow element 15a. The adjustable flow element 15a allows the volume flow of the coolant to be actively controlled or regulated. Alternatively or additionally, it is conceivable for the second flow element 15b to be adjustable.

[0067] Fig. 7 shows an embodiment of a cooling system 10 in which the compensating device 12 is designed as two parallel pipes. Each pipe contains a cooling circuit. The parallel pipes have a contact surface. The thermal energy is transferred from one cooling system to the other via the contact surface. In the present embodiment, thermal energy is transferred in the form of heat from the second cooling circuit K2 to the first cooling circuit K1. Alternatively, it is conceivable for the compensating device 12 to comprise a pipe-in-pipe arrangement.

[0068] Fig. 8 shows an embodiment of a cooling system 10, wherein the compensating device 12 comprises a mixing valve. The mixing valve is preferably designed as a multi-way valve. The mixing valve can, for example, be designed as a 4-way valve with at least 3 or more positions, wherein the two end positions represent a connection of the ports without mixing, or a very slight mixing. The intermediate position is to be designed according to the required mixing depending on the application, with any desired proportions being possible. Furthermore, continuous adjustment or control of the valve is possible. The compensating device 12 or the mixing valve is arranged downstream of the cooling unit 18 and downstream of the heating unit 19 in the corresponding cooling circuits. The mixing valve allows at least partial mixing of the coolant in the first cooling circuit K1 with the coolant in the second cooling circuit K2.

[0069] Fig. Figure 9 shows an embodiment of a cooling system 10 in which the compensating device 12 is arranged upstream of the first pump P1 in the first cooling circuit K1 and upstream of the second pump P2 in the second cooling circuit K2. The compensating device 12 is designed here as a mixing valve. The compensating device 12 is arranged at the position where the second valve 20b is arranged in the previous embodiment.

[0070] Fig. 10 shows an embodiment of a cooling system 10 which essentially corresponds to the embodiment according to Fig. 8. In contrast to the Fig. 8, the second valve 20b is in Fig. 10 is connected in such a way that, in combination with the compensating device 12 designed as a mixing valve, a single-circuit circuit is formed. This enables at least partial, in particular complete, mixing of the coolant in the first cooling circuit K1 with the coolant in the second cooling circuit K2.

[0071] Fig. 11 shows an embodiment of a cooling system which essentially corresponds to the embodiment according to Fig. 8. In contrast to the Fig. 8, in the present embodiment, the power electronics are arranged in the first cooling circuit K1. In other words, the power electronics 17 are arranged upstream of the energy storage device in the first cooling circuit K1.

[0072] Other embodiments of the present invention are possible and can be understood and carried out by those skilled in the art when applying the claimed subject matter from a study of the figures, the disclosure, and the appended claims. In particular, the respective parts / functions of the respective embodiment described above can also be combined with one another. Furthermore, various steps of the method can be carried out in a different order than disclosed here. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in dependent claims does not mean that a combination of these measures cannot be advantageous. Any reference signs in the claims should not be interpreted as limiting the scope of the claims. Reference symbol B1 first bypass circuit B2 second bypass circuit K1 first cooling circuit K2 second cooling circuit P1 first pump P2 second pump 10 Cooling system 11 Heat pump 12 Compensation device 13 Energy storage 14 electric machine 15 Flow element 16 Radiators 17 Power electronics 18 Cooling unit 19 Heating unit 20a first valve 20b second valve 21 Bypass valve

Claims

[1] Cooling system (10) for a vehicle, in particular an electric vehicle or a hybrid vehicle, comprising: - a heat pump (11) with an evaporator and a condenser, - a first cooling circuit (K1) associated with the evaporator, - a second cooling circuit (K2) assigned to the condenser, and - a compensating device (12) which is designed to exchange thermal energy between the first cooling circuit (K1) and the second cooling circuit (K2). [2] Cooling system (10) according to claim 1, wherein the compensating device (12) comprises a mixing valve, in particular a multi-way valve, and / or a heat exchanger, in particular a water-water heat exchanger. [3] Cooling system (10) according to claim 1 or 2, wherein an energy storage device (13) is arranged in the first cooling circuit (K1) and an electric machine (14) is arranged in the second cooling circuit (K2). [4] Cooling system (10) according to one of the preceding claims, wherein the compensating device (12) is arranged upstream of the heat pump (11) in a flow direction of a coolant. [5] Cooling system (10) according to one of the preceding claims, wherein in a flow direction of a coolant upstream of the compensating device (12) at least one flow element, in particular an orifice and / or throttle (15), is arranged for regulating a volume flow of the coolant. [6] Cooling system (10) according to one of the preceding claims, wherein the compensating device is arranged downstream of a radiator (16) and an energy storage device (13) in the flow direction of a coolant. [7] Cooling system (10) according to one of the preceding claims, wherein the compensating device (12) is configured to control the first cooling circuit (K1) and the second cooling circuit (K2) in such a way that switching between a single-circuit circuit or a dual-circuit circuit is possible. [8] Axle assembly comprising a cooling system (10) according to one of the preceding claims, power electronics (17) and an electric machine (14). [9] Vehicle with a cooling system (10) according to one of claims 1 to 7 or an axle assembly according to claim 8. [10] A method for cooling components of a vehicle comprising the following steps: - Operating an evaporator in a first cooling circuit (K1), - Operating a condenser in a second cooling circuit (K2), - exchanging thermal energy between the first cooling circuit (K1) and the second cooling circuit (K2), in particular to provide the evaporator with thermal energy corresponding to a minimum operating value of the evaporator.

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