Cooling system for a device with a fuel cell assembly and an electrical energy storage device and method for cooling a fuel cell assembly

Abstract

Cooling system (1) for a device with a fuel cell device (2) and an electrical energy storage device (3), comprising the cooling system (1): - a first cooling circuit (4) designed to cool the fuel cell assembly (2), and - a second cooling circuit (5) designed for cooling the electrical energy storage device (3), wherein the first cooling circuit (4) and the second cooling circuit (5) can be directly fluidically connected to each other.

Description

[0001] The invention relates to a cooling system for a device with a fuel cell assembly and an electrical energy storage device, a motor vehicle and a method for cooling a fuel cell assembly.

[0002] Optimizing the cooling system performance of fuel cell systems in fuel cell vehicles presents a significant challenge in their development. Compared to vehicles with internal combustion engines, the required heat dissipation capacity of the cooling system is higher. Furthermore, the required coolant temperature for cooling the fuel cell or fuel cell stack is lower, which results in a reduced efficiency of the heat exchangers, typically located at the front of the vehicle.

[0003] Under certain conditions, such as driving uphill in high ambient temperatures, some of the required drive energy could be supplied by the vehicle's high-voltage battery, thus reducing the power consumption of the fuel cell and consequently the load on the cooling system. However, battery capacity is limited and the battery charge level is variable, so this option is only available in a few applications or for a limited time. It should be noted that the term "battery" is used here for simplicity to refer to a rechargeable battery, also known as a secondary battery.

[0004] Therefore, the cooling system should be dimensioned to ensure sufficient cooling capacity under virtually all conditions. This necessitates a large cooling system, particularly the heat exchanger(s) in the front of the vehicle. Optionally, reducing the fuel cell output for certain conditions, such as driving uphill at high ambient temperatures, can be considered to decrease cooling requirements. However, this may potentially lead to lower customer satisfaction.

[0005] Numerous concepts for linking cooling circuits are known from the state of the art, which also have at least an indirect effect on the cooling of fuel cells.

[0006] From DE 10 2015 015 635 A1, DE 10 2018 219 203 A1, DE 10 2009 035 471 A1 and US 9 136 549 B2, a thermal coupling of a fuel cell cooling circuit with a battery cooling circuit is known. However, this does not allow for separation of the two cooling circuits, but rather they are always coupled. Furthermore, DE 10 2010 032 886 A1 discloses a coupling of a fuel cell charge air cooling circuit with a battery cooling circuit.

[0007] Against this background, the object of the invention is to further optimize the cooling of a fuel cell device, in particular designed for the propulsion of a motor vehicle.

[0008] This task is solved by the subject matter of the independent claims; the dependent claims concern specific configurations.

[0009] A first aspect of the invention relates to a cooling system for a device comprising a fuel cell assembly and an electrical energy storage device. The fuel cell assembly can comprise one or more fuel cells, for example in the form of a fuel cell stack. The electrical energy storage device can be a battery, preferably a high-voltage battery, such as those used, for example, as a traction battery in a motor vehicle.

[0010] The device can be arranged, in particular, in a motor vehicle, where a motor vehicle is understood to be a vehicle powered by at least one engine, e.g., a land, air, or water vehicle. The motor vehicle can preferably be a passenger car or a truck. In other words, the proposed cooling system can be designed to cool a fuel cell unit and a traction battery of a motor vehicle.

[0011] The cooling system comprises a first cooling circuit, designed for cooling the fuel cell unit, and a second cooling circuit, designed for cooling the electrical energy storage device. The first and second cooling circuits are directly fluidically connected. In this context, "directly fluidically connected" means that the two cooling circuits can be coupled in such a way that the same coolant can flow through at least sections of both circuits. "Connectable" or "coupling" means that the two cooling circuits can be either separated or coupled, as explained in more detail below.

[0012] The direct fluidic connection can be realized, for example, by means of coolant lines that can transport coolant from the first cooling circuit from a withdrawal point to the second cooling circuit and from the second cooling circuit to a return point in the first cooling circuit.

[0013] A water / glycol mixture, possibly with additives, can be used as a coolant in both cooling circuits, provided it meets the requirements of both circuits. When the cooling circuit(s) are activated, the coolant flows in the respective circuit or in the connected cooling circuits.

[0014] As mentioned, the first cooling circuit is designed to cool the fuel cell unit. For example, the first cooling circuit can be used to maintain a maximum temperature of the fuel cell unit, measured directly upstream of the fuel cell unit or at its inlet, in the range between 55 °C and 60 °C.

[0015] The first cooling circuit may include a heat exchanger, for example, for heat transfer between the coolant and the ambient air. Advantageously, such a heat exchanger can be located in the front of a vehicle equipped with the cooling system to ensure optimal heat dissipation. To create and increase coolant flow in the first cooling circuit, it may include a coolant pump, such as a water pump.

[0016] Optionally, a bypass line can be installed to circumvent the heat exchanger, along with a temperature control valve located at a branch point of the bypass line, i.e., at the outlet or return point. The temperature control valve allows the coolant temperature to be influenced within a certain range by diverting more or less coolant through the bypass line instead of to the heat exchanger, thus reducing its cooling. For this purpose, the temperature control valve can work in conjunction with a temperature sensor, which, for example, can be located directly upstream of the fuel cell unit or at its inlet and measures the coolant temperature, enabling control of the coolant temperature.

[0017] Optionally, an expansion vessel can also be integrated into the first cooling circuit.

[0018] As mentioned, the second cooling circuit is designed to cool the electrical energy storage device. For example, the second cooling circuit can be used to maintain a maximum temperature of the electrical energy storage device between 25 °C and 40 °C. To achieve this temperature, the coolant temperature in the second cooling circuit can be, for example, below 25 °C to 30 °C, measured directly upstream of the electrical energy storage device or at its inlet. Depending on the cooling concept of the electrical energy storage device, the coolant temperature upstream of the electrical energy storage device can also be significantly lower than the specified values.

[0019] The second cooling circuit can include a radiator to cool the coolant flowing in the second cooling circuit. Preferably, the radiator can facilitate heat transfer between the coolant and a refrigerant. In other words, the second cooling circuit can include a radiator thermally coupled to a refrigerant circuit.

[0020] The refrigerant circuit can, as usual, include an electrically driven refrigerant compressor and a condenser. Optionally, an evaporator, e.g., for cooling a vehicle interior, can be integrated into the refrigerant circuit.

[0021] To create and increase coolant flow in the second cooling circuit, this circuit can include a coolant pump, e.g., a water pump. Optionally, an expansion tank can be integrated into the second cooling circuit.

[0022] Preferably, the first and second cooling circuits can be operated essentially at ambient pressure, i.e., both cooling circuits are not refrigerant circuits.

[0023] The possibility of a direct fluidic connection between the first and second cooling circuits allows, on the one hand, separate cooling of the fuel cell unit and the electrical energy storage system when they are not connected. This ensures the necessary cooling, particularly of the electrical energy storage system.

[0024] Secondly, when connected, the fuel cell system can be additionally cooled using the cooling capacity of the second cooling circuit, for example, by utilizing the cooler integrated within it. This can enable the fuel cell system to operate at higher power levels, which would otherwise be impossible due to insufficient cooling of the fuel cell system or only possible with a correspondingly large cooling system, resulting in high costs and a large space requirement.

[0025] According to various design variants, it can be provided that in a first operating mode the first cooling circuit and the second cooling circuit can be operated separately from each other.

[0026] This first operating mode advantageously allows for independent cooling of the fuel cell unit and the electrical energy storage system. This makes it easy to meet the different cooling requirements of the fuel cell unit and the electrical energy storage system.

[0027] Preferably, the cooling system is operated in the first operating mode when cooling is required for both the fuel cell unit and the electrical energy storage device. Reference is made to the following explanations in this regard.

[0028] According to further design variants, in a second operating mode the first cooling circuit and the second cooling circuit can be operated coupled together without integrating the electrical energy storage.

[0029] In other words, a cooling circuit can be designed that includes the first cooling circuit, parts of the second cooling circuit (i.e., excluding the section containing the electrical energy storage device), and connecting lines between the first and second cooling circuits. Appropriate branch points can be provided in the first and second cooling circuits for this purpose, which can be suitably equipped with one or more flow control valves.

[0030] If the cooler of the second cooling circuit is coupled to a refrigerant circuit, this cooler can preferably be activated or activated in the second operating mode.

[0031] The second operating mode advantageously allows the cooling capacity of the second cooling circuit to be used for cooling the fuel cell unit. By appropriately mixing the coolant, which is significantly cooled in the second cooling circuit, with the coolant in the first cooling circuit, the coolant temperature can be adjusted as needed directly upstream of the fuel cell unit, i.e., depending on the required cooling capacity, which in turn depends, among other things, on the current power output of the fuel cell unit. For example, a further reduction in the coolant temperature of 5 to 10 K can be achieved.

[0032] According to further design variants, the cooling system can have a control unit, set up and designed to generate control signals that cause the cooling system to operate in the first or second operating mode.

[0033] The control unit can be implemented in hardware and / or software and can be physically designed as a single component or in multiple parts. In particular, the control unit can be part of a drive control system or integrated into it.

[0034] The control unit is in a signal-technical functional connection with one or more actuators of the cooling circuits, e.g. flow control valves, in order to transmit the generated control signals to them and thus be able to control the operation of the cooling system.

[0035] The control unit allows selective operation of the cooling system in the first or second operating mode. Additional operating modes can be provided as an option.

[0036] Preferably, the control unit can be configured and designed to generate control signals depending on the temperature of the electrical energy storage device and the temperature of the fuel cell device. In other words, the control unit can enable a targeted selection of the first or second operating mode based on the temperatures of the electrical energy storage device and the fuel cell device.

[0037] The control unit can receive sensor signals from temperature sensors measuring the temperature of the fuel cell unit or the electrical energy storage unit, process these signals according to instructions or code programmed into the control unit, and send the control signals to one or more actuators of the cooling system. The temperature sensors for measuring the temperatures of the fuel cell unit and the electrical energy storage unit can, for example, be part of the proposed cooling system. The temperature of the electrical energy storage unit, e.g., the battery cell temperature, can also be measured directly with a temperature sensor appropriately located on or within the electrical energy storage unit.

[0038] Optionally, the control unit can generate the control signals taking into account at least one influencing factor. The influencing factor(s) can be selected from a group including: the state of charge of the electrical energy storage device, the speed of a vehicle equipped with the cooling system, the ambient temperature, the required drive power of the vehicle equipped with the cooling system, and the opening position of a coolant valve.

[0039] In other words, one or more of the influencing factors, in addition to the temperatures of the fuel cell device and the electrical energy storage device, can be used to decide on the operation of the cooling system in the first or second operating mode, to generate corresponding control signals and output them to the actuators of the cooling system.

[0040] According to further embodiment variants, it can be provided that a withdrawal point for a cooling medium from the first cooling circuit is located downstream of a heat exchanger arranged in the first cooling circuit and upstream of the fuel cell device to be cooled.

[0041] This means that when the first and second cooling circuits are connected, i.e., in the second operating mode, coolant pre-cooled by the heat exchanger in the first cooling circuit is directed into the second cooling circuit and cooled further there, e.g. by means of the cooler located in the second cooling circuit and operated with a refrigerant circuit.

[0042] Alternatively or additionally, a cooling medium extraction point can be located downstream of the fuel cell unit to be cooled and upstream of a heat exchanger arranged in the first cooling circuit. Preferably, the extraction point can be located downstream of a temperature control valve located at a branch point of a bypass line for bypassing the heat exchanger of the first cooling circuit.

[0043] This means that when the first and second cooling circuits are connected, i.e., in the second operating mode, the coolant heated by contact with the fuel cell unit is first directed into the second cooling circuit and cooled there, for example, by means of the cooler located in the second cooling circuit and operated with a refrigerant circuit. In this case, the coolant supplied to the cooler therefore has a higher temperature than in the previously described variant.

[0044] The preferred position of the extraction point can depend, among other things, on the operating parameters of the cooler, e.g., its inlet temperature range. The two described options for positioning the extraction point allow for optimization of the cooling capacity of the fuel cell system, particularly when adapted to the specific operating parameters of the cooler.

[0045] According to further design variants, a return point for the cooling medium can be located downstream of the heat exchanger arranged in the first cooling circuit and upstream of the fuel cell device to be cooled.

[0046] This enables efficient cooling of the fuel cell device, as the supply of the coolant cooled in the second cooling circuit is returned to the first cooling circuit as directly as possible upstream of the fuel cell device.

[0047] Another aspect of the invention relates to a motor vehicle with a fuel cell device, an electrical energy storage device and a cooling system as described above.

[0048] Therefore, the above explanations of the proposed cooling system also serve to describe the motor vehicle. The advantages of the cooling system are correspondingly linked to the motor vehicle.

[0049] Another aspect of the invention relates to a method for cooling a fuel cell device by means of a cooling system according to the preceding description, wherein the cooling system is operated in the first operating mode if cooling of the electrical energy storage is required, and wherein the cooling system is operated in the second operating mode if no cooling of the electrical energy storage is required.

[0050] The proposed method is implemented using the cooling system described above. Therefore, the above explanations of the cooling system also serve to describe the proposed method. The advantages of the cooling system are thus inherent in the method. The method can, for example, be implemented in a motor vehicle equipped with a suitable cooling system, a fuel cell unit, and an electrical energy storage device.

[0051] For further explanation of the conditions under which cooling of the electrical energy storage device is or is not required, please refer to the following sections. Cooling of the electrical energy storage device may not be necessary, in particular, if its temperature is already low enough without cooling and / or if the state of charge of the electrical energy storage device is too low for further use and the electrical energy storage device is therefore deactivated.

[0052] Depending on the design, the power output of the fuel cell system can vary depending on whether the cooling system is operated in the first or second operating mode.

[0053] For example, operating the cooling system in the second operating mode may result in higher fuel cell performance than operating the cooling system in the first operating mode. In other words, the fuel cell performance may be higher in the second operating mode than in the first.

[0054] The possibility of increasing the power output of the fuel cell system in the second operating mode compared to the first operating mode can also enable the fuel cell system to fully or almost fully meet the power requirements under difficult operating conditions, e.g., high ambient temperature, driving uphill, etc.

[0055] Further advantages of the present invention can be seen from the illustrations and the accompanying description, with reference to which the invention will be explained in more detail below.

[0056] They show: Fig. 1 a schematic representation of a cooling system with cooling circuits according to the state of the art; Fig. 2 a schematic representation of a cooling system of a first embodiment; Fig. 3 the cooling system of the first embodiment in the first operating mode; Fig. 4 the cooling system of the first embodiment in the second operating mode; Fig. 5 a schematic representation of a cooling system of a second embodiment; Fig. 6. A flowchart of an exemplary procedure; Fig. 7. A representation of how the fuel cell system and the electrical energy storage system may meet a performance requirement; and Fig. 8 a schematic representation of an exemplary motor vehicle.

[0057] Fig. Figure 1 shows a prior art cooling system 1, which can be used, for example, in a motor vehicle 100, whose drive energy is supplied by a fuel cell device 2 and an electrical energy storage device 3, i.e., a battery. Both the fuel cell device 2 and the electrical energy storage device 3 typically require cooling to ensure that the fuel cell device FC does not exceed a temperature limit. Thresh or a temperature limit of the electrical energy storage device (Batt). Thresh not to be exceeded.

[0058] According to the state of the art, separate cooling circuits are provided for cooling, i.e., a first cooling circuit 4 for cooling the fuel cell device 2 and a second cooling circuit 5 for cooling the electrical energy storage device 3. The cooling of the fuel cell device 2 and the electrical energy storage device 3 is therefore completely independent of each other.

[0059] The first cooling circuit 4 is formed by coolant lines 21a, which connect the individual components of the first cooling circuit 4 and through which a coolant flows. A coolant pump 14a is provided to create a coolant flow in the first cooling circuit 4. Furthermore, a heat exchanger 12 is arranged in the first cooling circuit 4, which enables heat transfer between the coolant and the environment. The heat exchanger 12 is therefore designed as a coolant-to-air heat exchanger. The heat exchanger 12 can preferably be arranged in a front area of ​​the vehicle 100 to enable the best possible heat dissipation to the environment with the least possible influence from other heat exchangers present in the vehicle 100.

[0060] The first cooling circuit 4 can also have a bypass line 22 to bypass the heat exchanger 12. A temperature control valve 18, which is located, for example, on the [unclear text] Fig. The position shown in Figure 1 in the first cooling circuit 4, i.e., at a branch point of the bypass line 22, allows the control valve to determine whether and how much coolant flows through the bypass line 22 and is therefore not cooled by the heat exchanger 12. By adjusting the position of the temperature control valve 18, the temperature of the coolant in the first cooling circuit 4 can be controlled within certain limits. An expansion tank (not shown) can optionally be provided in the first cooling circuit 4.

[0061] The second cooling circuit 5 is formed by coolant lines 21b, which connect the individual components of the second cooling circuit 5 and through which a coolant flows. A coolant pump 14b is provided to create a coolant flow in the second cooling circuit 5. An expansion tank (not shown) can optionally also be provided in the second cooling circuit 5.

[0062] Furthermore, a cooler 10 is arranged in the second cooling circuit 5. This cooler is thermally coupled to a refrigerant circuit 9 and enables heat transfer between the coolant and a refrigerant flowing in the refrigerant circuit 9. The cooler 10 is thus designed as a coolant-refrigerant heat exchanger. Due to the thermal coupling of the second cooling circuit 5 with the refrigerant circuit 9 via the cooler 10, a greater cooling of the coolant in the second cooling circuit 5 is achieved compared to the first cooling circuit 4. This allows for a lower temperature of the electrical energy storage T. Batt compared to the temperature of the fuel cell device T FC can be achieved.

[0063] The refrigerant circuit 9, which is thermally coupled to the second cooling circuit 5, is constructed in the usual manner. The refrigerant circuit 9 comprises a refrigerant compressor 17 and a condenser 16, as well as a refrigerant valve 20, the operation of which is known to those skilled in the art. Furthermore, an evaporator 15 is provided, which can, for example, be located in the interior of the motor vehicle 100 and can be used for air conditioning, in particular cooling, of the vehicle interior.

[0064] As already mentioned, according to the prior art, the two cooling circuits 4 and 5 are always designed separately from each other. This means that if the fuel cell unit 2 is not sufficiently cooled, its power output can be reduced or at least not increased in order to exceed the upper temperature limit of the fuel cell unit FC. Threshnot to be exceeded. This can have a particularly negative impact if it is no longer possible to drive the motor vehicle 100 using the electrical energy storage device 5, for example, because the charge level of the electrical energy storage device 5 is no longer sufficient. In order to maintain the desired drive power of the motor vehicle 100, the reduced output of the electrical energy storage device 5 would have to be compensated for by the fuel cell unit 2, which is usually accompanied by an increase in the temperature of the fuel cell unit T. FC and consequently a higher cooling requirement, which cannot be covered by the first cooling circuit 4 alone.

[0065] In order to improve the cooling of the fuel cell device 2 in, among other things, the aforementioned situation, a modification of the cooling system 1 is proposed. Fig. Figure 2 shows a first embodiment of such a modified cooling system 1 in a schematic representation. The following only highlights the differences compared to cooling system 1 of the Fig. 1 explained, so that otherwise reference is made to the explanations regarding Fig. 1 is referred to.

[0066] Cooling system 1 of the Fig. The system is characterized by the fact that the first cooling circuit 4 and the second cooling circuit 5 can be directly connected fluidically. For this purpose, a supply line 23 and a return line 24 are provided, which, when required, convey the coolant from a withdrawal point 11 located in the first cooling circuit 4 to the second cooling circuit 5 and from the second cooling circuit 5 to a return point 13 located in the first cooling circuit 4. Water, optionally with additives, is used as the coolant.

[0067] In the first embodiment, the extraction point 11 is arranged downstream of the heat exchanger and upstream of the fuel cell device 2. In other words, when the cooling system 1 is operated in the second operating mode B (see the following explanation of the operating modes), the heat exchanger 12 and the cooler 10 are arranged parallel to each other with respect to the flow rate of the coolant.

[0068] The return point 13 is located downstream of the heat exchanger 12 and upstream of the fuel cell assembly 2. In the first embodiment, the extraction point 11 is also located upstream of the return point 13.

[0069] To couple the first cooling circuit 4 with the second cooling circuit 5 as needed, i.e., only when certain conditions are met, a coolant valve 8 is provided. The on-demand coupling of the two cooling circuits 4 and 5 is realized by means of a control unit 6 and control signals 7 generated and output by the control unit 6, which are sent to the coolant valve 8 and cause a change in the valve position, i.e., the opening state of the coolant valve 8.

[0070] The control unit 6 can process the control signals 7, in particular depending on the temperature of the electrical energy storage device T. Batt and the temperature of the fuel cell device T FC generate, as below with reference to Fig. Section 6 explains this in more detail. To determine the temperature of the electrical energy storage device T Batt and the temperature of the fuel cell device T FCTemperature sensors may be provided (not shown), whose sensor signals are transmitted to and processed by the control unit 6. A temperature sensor for determining the temperature of the electrical energy storage device T Batt For example, it can be arranged directly in or on the electrical energy storage device 3 to directly measure the battery cell temperature. A temperature sensor for determining the temperature of the fuel cell unit T FC For example, it can be arranged in the first cooling circuit 4 immediately upstream of the fuel cell device 2 in order to measure the coolant temperature at the inlet of the fuel cell device 2.

[0071] In the exemplary embodiment, the coolant valve 8 is designed as a three-way valve. This allows the valve position of the coolant valve 8 to determine, on the one hand, whether the first and second cooling circuits 4, 5 are coupled or not, and on the other hand, whether the electrical energy storage device 3 is integrated into the cooling circuit or not. This will be explained below with reference to the Fig. 3 and Fig. 4 explained in more detail. The function of the coolant valve 8 as a three-way valve can alternatively also be implemented by two separate valves.

[0072] Fig. Figure 3 shows the cooling system 1 of the first embodiment according to Fig. 2 in a first operating mode A, in which the first cooling circuit 4 and the second cooling circuit 5 are operated separately. Consequently, the cooling of the fuel cell device 2 and the electrical energy storage device 3 takes place independently of each other according to the respective cooling requirements.

[0073] To activate the first operating mode A, the control unit 6 generates a control signal 7, which is output to the coolant valve 8 and causes the flow into the return line 24 to be interrupted and the electrical energy storage device 3 to be integrated into the second cooling circuit 5.

[0074] Fig. Figure 4 shows the cooling system 1 of the first embodiment according to Fig. 2 in a second operating mode B, in which the first cooling circuit 4 and the second cooling circuit 5 are operated in conjunction, but the electrical energy storage device 3 is not integrated into the second cooling circuit 5. This means, firstly, that in the second operating mode B, the electrical energy storage device 3 is not cooled by the cooling system 1. Secondly, the fuel cell device 2 is cooled more intensively by cooling the coolant not only by means of the heat exchanger 12, but also by means of the cooler 10.

[0075] To activate the second operating mode B, the control unit 6 generates a control signal 7, which is output to the coolant valve 8. This enables flow into the return line 24 and interrupts the flow towards the electrical energy storage device 3. By influencing the flow rate into the return line 24, a coolant mixing temperature can be set to meet the cooling requirements of the fuel cell unit 2 without unnecessarily burdening or activating the refrigerant circuit 9. The flow rate into the return line 24 can also be influenced by a control signal 7, generated by the control unit 6 and output to the coolant valve 8, which causes a corresponding change in the valve opening.

[0076] In the second operating mode B, the bypass line 22 can also preferably be deactivated, so that the entire coolant flows through the heat exchanger 12 and is cooled as much as possible.

[0077] In Fig. Figure 5 schematically illustrates a second embodiment of a cooling system 1. The following section describes only the changes compared to the cooling system of the first embodiment ( Fig. 2) explained in more detail; otherwise, reference is made to the explanation of the first embodiment. In particular, the two operating modes A and B can also be implemented analogously with the cooling system 1 of the second embodiment.

[0078] The cooling system 1 of the second embodiment differs from the cooling system 1 of the first embodiment with respect to the positioning of the extraction point 11. While the extraction point 11 in the first embodiment is located downstream of the heat exchanger 12 and upstream of the fuel cell assembly 2, the extraction point 11 in the second embodiment, as shown in Fig. Figure 5 shows the heat exchanger 12 arranged downstream of the fuel cell assembly 2 and upstream of the heat exchanger 12. In other words, when the cooling system 1 is operated in the second operating mode B, the heat exchanger 12 and the cooler 10 are arranged parallel to each other with respect to the coolant flow rate.

[0079] This results in the coolant being fed into the second cooling circuit 5 via the supply line 23 in the second operating mode B having a higher temperature compared to the first embodiment, since it previously cooled the fuel cell unit 2 and absorbed heat in the process. Depending on the configuration of the refrigerant circuit 9, this can have a positive effect on the subsequent cooling of the coolant by means of the cooler 10.

[0080] Fig. Figure 6 shows a flowchart of an exemplary method 200 for cooling a fuel cell device 2. The method 200 can be implemented, for example, using the cooling system 1 of the first embodiment described above ( Fig. 2) or the second embodiment ( Fig. 5) be carried out.

[0081] In process step S1, the temperature of the electrical energy storage device T is determined. Battdetermined, e.g. by means of one or more temperature sensors in or on the electrical energy storage device 3 or in or on the battery cells.

[0082] In process step S2, the temperature of the fuel cell device T is FC determined, e.g. by means of another temperature sensor, which can be arranged, e.g., directly upstream of the fuel cell unit 2 and determines the temperature of the coolant at this point, from which the temperature of the fuel cell unit T can be determined. FC can be derived.

[0083] In process step S3, it is checked whether cooling of the electrical energy storage device 3 is necessary. For this purpose, it can be determined, for example, whether the temperature of the electrical energy storage device T Batt the upper temperature limit of the electrical energy storage device (Batt) Thresh exceeds, i.e., whether T Batt > Battery ThreshThis applies. The upper temperature limit of the electrical energy storage device (Batt) is... Thresh For example, it can be in the range between 30 °C and 45 °C, particularly in the range between 35 °C and 40 °C, e.g., at 38 °C. If the upper temperature limit of the electrical energy storage device (Batt) is exceeded... Thresh The proper functioning of the electrical energy storage device 2 is no longer ensured, so cooling to a temperature below the upper temperature limit Batt Thresh This should be done.

[0084] If it is determined in process step S3 that cooling of the electrical energy storage device 3 is required, then T applies. Batt > Battery Thresh , so the procedure 200 continues with procedure step S4.

[0085] In process step S4, the cooling system 1 is operated in the first operating mode A. In other words, the first cooling circuit 4 and the second cooling circuit 5 are operated separately. This allows the electrical energy storage device 3 to be adequately cooled. Process 200 can then be continued with process step S1, meaning it can be continuously checked whether T Batt > Battery Thresh applies and whether or not cooling of the electrical energy storage device 3 is still required.

[0086] If, however, it is determined in process step S3 that no cooling of the electrical energy storage device 3 is required, then T applies. Batt > Battery Thresh If not, the procedure 200 continues with procedure step S5.

[0087] In process step S5, it is checked whether cooling of the fuel cell unit 2 is necessary. For this purpose, it can be determined, for example, whether the temperature of the fuel cell unit T FC the temperature limit of the fuel cell device FC Thresh exceeds, i.e., whether T FC > FC Thresh The temperature limit of the fuel cell unit FC applies. Thresh For example, it can be in the range between 50 °C and 65 °C, particularly in the range between 55 °C and 60 °C, e.g., at 55 °C. If the upper temperature limit of the fuel cell device (FC) is exceeded... Thresh The proper functioning of the fuel cell unit 2 is no longer ensured, so cooling to a temperature below the temperature limit FC is not possible. Thresh This should be done. Alternatively or additionally, the power output of fuel cell unit 2 could be reduced, for example to prevent damage to it.

[0088] If it is determined in process step S5 that cooling of the fuel cell unit 2 is required, then T applies. FC > FC Thresh , so the procedure 200 continues with procedure step S6.

[0089] In process step S6, the cooling system 1 is operated in the second operating mode B. In other words, the first cooling circuit 4 and the second cooling circuit 5 are coupled together, with the electrical energy storage device 3 not being integrated and consequently no longer being cooled. In the exemplary embodiment, the cooler 10 of the second cooling circuit 5 is activated, i.e., the refrigerant circuit 9 is in an activated state or is being activated. The fuel cell device 2 is cooled more intensively in the second operating mode B, since the coolant is cooled not only by the heat exchanger 12 but also by the cooler 10. The process 200 can then be continued again with process step S1, i.e., it can be continuously checked whether T Batt > Battery Thresh applies and whether or not cooling of the electrical energy storage device 3 is required.

[0090] If, however, it is determined in process step S5 that no cooling of the electrical energy storage device 3 is required, then Te applies. a tt > Batt Thresh If not, the procedure 200 continues with procedure step S7.

[0091] In process step S7, the cooler 10 is deactivated, for example by deactivating the refrigerant circuit. The process can then be continued with process step S1.

[0092] Process steps S1 and S2 can also be carried out in reverse order or at least partially in parallel, and in particular continuously. Furthermore, process step S2 can also be performed at a later time, when the temperature of the fuel cell device T has reached a certain level. FC for the further execution of procedure 200, i.e. e.g. if procedure step S3 shows that T Batt > Battery Thresh applies.

[0093] In addition to the temperatures of the electrical energy storage T Batt and the fuel cell facility T FC Further influencing factors can be considered when deciding whether the cooling system 1 operates in the first operating mode A or the second operating mode B. Such possible additional influencing factors include the state of charge of the electrical energy storage device 3, the speed of a motor vehicle 100 equipped with the cooling system 1, the ambient temperature, the required drive power of the motor vehicle 100, and the opening position of the coolant valve 8. By including one or more of these influencing factors, a more stable control of the coolant temperature can be achieved.

[0094] The following refers to the Fig. 7 a possible inclusion of the influencing factors state of charge of the electrical energy storage 3 and required drive power of the motor vehicle 100 explained in more detail.

[0095] In Fig. 7 considers a mountain-up journey of a motor vehicle 100 equipped with the cooling system 1, wherein the drive of the motor vehicle 100 can be carried out either by means of the electrical energy storage device 3 or the fuel cell device 2 or in combination by means of the electrical energy storage device 3 and the fuel cell device 2.

[0096] The x-axis represents the distance or duration of the uphill journey, and the y-axis represents the drive power of the vehicle 100. It is assumed, for the sake of simplicity, that a constant drive power is required for the entire uphill journey. This required drive power can be supplied by the power of the fuel cell unit 2 and / or the power of the electrical energy storage device 3; that is, the combined power of the fuel cell unit 2 and the power of the electrical energy storage device 3 equal the required drive power.

[0097] At the start of the uphill journey, the cooling system 1 operates in the first operating mode 1, i.e., with separate cooling circuits 4 and 5. The available power of the fuel cell unit 2 is limited by the cooling of the fuel cell unit 2, i.e., by the capacity of the first cooling circuit 4. Since the electrical energy storage device 3 is sufficiently cooled in the first operating mode A, it can contribute to the drive power. In other words, the drive power of the vehicle 1 during the first operating mode 1 is supplied by both the fuel cell unit 2 and the electrical energy storage device 3.

[0098] As the distance or time increases, the state of charge of the electrical energy storage device 3 decreases. At time X, or after covering a distance X, a lower limit of the state of charge is reached, for example, a remaining capacity of 5%. To prevent damage to the electrical energy storage device 3, for example, it must be deactivated at point X and can subsequently no longer provide power. Consequently, the power output of the electrical energy storage device 3 drops to zero.

[0099] If the cooling system were to continue operating in the first operating mode A, the power previously supplied by the electrical energy storage device 2 would be lacking, meaning that the required drive power of the vehicle 100 could no longer be met. To avoid this, the cooling system 1 is operated in the second operating mode B from point X onwards.

[0100] Since a higher cooling capacity is available for cooling the fuel cell unit 2 in the second operating mode B, the power output of the fuel cell unit 2 can be increased so that the required drive power can be fully or almost fully met by the fuel cell unit 2. In other words, the power output of the fuel cell unit 2 is variable depending on whether the cooling system 1 is operated in the first or second operating mode A, B.

[0101] Fig.Figure 8 shows an exemplary motor vehicle 100 in a schematic representation. The motor vehicle 100 is designed as a passenger car and has a fuel cell unit 2 and an electrical energy storage device 3, which can optionally provide the drive power of the motor vehicle 100 individually or together. The fuel cell unit 2 and the electrical energy storage device 3 are cooled by a cooling system 1, which is designed according to the first or second embodiment and enables cooling in the first or second operating mode A, B.

[0102] The proposed cooling system and the associated method enable an increase in the cooling capacity of the fuel cell unit 2 by integrating the cooling of the electrical energy storage device 3, thus allowing the fuel cell unit 2 to operate at a higher power output. This prevents a reduction in the vehicle's drive power due to insufficient power from the fuel cell unit 2. Alternatively, while maintaining the same power output of the fuel cell unit 2, its cooling system can be made smaller, thereby saving installation space. An optimization between these two options is also possible. Reference symbol list 1 Cooling system 2 Fuel cell system 3 electrical energy storage 4 first cooling circuit 5 second cooling circuit 6 Control unit 7 Control signal 8 Coolant valve 9 Refrigerant circuit 10 coolers 11 Sampling point 12 heat exchangers 13 Return point 14a, 14b Coolant pump 15 evaporators 16 Capacitor 17 Refrigerant compressor 18 Temperature control valve 19 Evaporator valve 20 Refrigerant valve 21a, 21b Coolant line 22 Bypass line 23 Supply line 24 Return line 100 motor vehicles 200 procedures A first operating mode B second operating mode T Batt Temperature of the electrical energy storage device T FC Fuel cell device temperature FC Thresh Temperature limit of the fuel cell device Battery Thresh upper temperature limit of the electrical energy storage S1 Determining the temperature of the electrical energy storage device S2 Determining the temperature of the fuel cell unit S3 Check if cooling of the electrical energy storage device is required S4 Operating the cooling system in the first operating mode S5 Check if cooling of the fuel cell unit is required S6 Operating the cooling system in the second operating mode S7 Disabling the cooler

Claims

[1] Cooling system (1) for a device with a fuel cell device (2) and an electrical energy storage device (3), comprising the cooling system (1): - a first cooling circuit (4) designed to cool the fuel cell assembly (2), and - a second cooling circuit (5) designed for cooling the electrical energy storage device (3), wherein the first cooling circuit (4) and the second cooling circuit (5) can be directly fluidically connected to each other. [2] Cooling system (1) according to claim 1, wherein in a first operating mode (A) the first cooling circuit (4) and the second cooling circuit (5) can be operated separately from each other. [3] Cooling system (1) according to one of the preceding claims, wherein in a second operating mode (B) the first cooling circuit (4) and the second cooling circuit (5) are coupled together and can be operated without the integration of the electrical energy storage device (3). [4] Cooling system (1) according to claim 3 in combination with claim 2, comprising a control unit (6) configured and designed to generate control signals (7) that cause the cooling system (1) to be operated in the first or second operating mode (A, B). [5] Cooling system (1) according to claim 4, wherein the control unit (6) is for generating the control signals (7) depending on a temperature of the electrical energy storage device (T Batt ) and a temperature of the fuel cell device (T FC ) is set up and staffed. [6] Cooling system (1) according to claim 5, wherein the control unit (6) is for generating the control signals (7) taking into account at least one influencing factor, the influencing factor being selected from a group comprising: a state of charge of the electrical energy storage device (3), a speed of a motor vehicle (100) equipped with the cooling system (1), an ambient temperature, a required drive power of the motor vehicle (100) equipped with the cooling system (1) and an opening position of a coolant valve (8). [7] Cooling system (1) according to one of the preceding claims, wherein the second cooling circuit (5) has a cooler (10) coupled to a refrigerant circuit (9). [8] Cooling system (1) according to one of the preceding claims, wherein a withdrawal point (11) for a cooling medium from the first cooling circuit (4) is arranged downstream of a heat exchanger (12) arranged in the first cooling circuit (4) and upstream of the fuel cell device (2). [9] Cooling system (1) according to one of the preceding claims, wherein a withdrawal point (11) for a cooling medium from the first cooling circuit (4) is arranged downstream of the fuel cell device (2) and upstream of a heat exchanger (12) arranged in the first cooling circuit (4). [10] Cooling system (1) according to one of the preceding claims, wherein a return point (13) for the cooling medium is arranged in the first cooling circuit (4) downstream of the heat exchanger (12) arranged in the first cooling circuit (4) and upstream of the fuel cell device (2). [11] Motor vehicle (100) comprising a fuel cell device (2), an electrical energy storage device (3) and a cooling system (1) according to any of the preceding claims. [12] Method (200) for cooling a fuel cell device (2) by means of a cooling system (1) according to any one of claims 1 to 10, wherein the cooling system (1) is operated in the first operating mode (A) if cooling of the electrical energy storage device (3) is required, and wherein the cooling system is operated in the second operating mode (B) if no cooling of the electrical energy storage device (3) is required. [13] Method (200) according to claim 12, wherein the power output of the fuel cell device (2) is variable depending on whether the cooling system (1) is operated in the first or second operating mode (A, B).

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