DE102022209358A1 - Method for operating a cooling system for a motor vehicle - Google Patents

Abstract

Method for operating a cooling system (53) for cooling at least one component (10, 11, 48, 50, 51) of a drive system with a traction electric motor (4) for a motor vehicle (1) with the steps: passing coolant through one filled with coolant Coolant circuit with at least one coolant line (37) and a heat exchanger (39) by conveying the coolant through the cooling circuit with a coolant conveying device (56), passing cooling air through the heat exchanger (37) by feeding the cooling air with a cooling air conveying device (5) through the heat exchanger (37) is conveyed, transferring heat from the coolant passed through the heat exchanger (37) to the cooling air passed through the heat exchanger (37), passing the cooling air passed through the heat exchanger (37) through at least one air line (57), whereby the Flow resistance of the cooling air conducted through the heat exchanger (37) is controlled and / or regulated depending on the requested braking power of the motor vehicle (1).

Description

The present invention relates to a method for operating a cooling system according to the preamble of claim 1, a cooling system for a motor vehicle according to the preamble of claim 11, a drive system according to the preamble of claim 14 and a motor vehicle according to the preamble of claim 15.

State of the art

Fuel cell units as galvanic cells convert continuously supplied fuel and oxidant into electrical energy using redox reactions at an anode and cathode. Fuel cells are used in a wide variety of stationary and mobile applications, for example in houses without a connection to a power grid or in motor vehicles, in rail transport, in aviation, in space travel and in shipping. In the fuel cell unit, a large number of fuel cells are stacked to form the fuel cell stack as a fuel cell stack. Channels for passing fuel, channels for passing oxidant and channels for passing coolant are integrated in the fuel cell stack. The fuel is stored in a pressure vessel. For example, hydrogen acts as a fuel and air from the environment acts as an oxidizing agent. In a fuel cell system, in addition to the fuel cell unit, there is, for example, a fuel supply system with a pressure vessel for the fuel, a cooling system with a cooling circuit for cooling the fuel cell unit and an oxidant supply system with a gas conveying device, for example a turbo compressor, for conveying oxidant as air from the environment through the Fuel cell unit.

A fuel cell system is used in a motor vehicle to drive the wheels of the motor vehicle. There is also an electrical high-voltage system with a traction electric motor, an inverter and a traction battery as a buffer storage for electrical energy. The fuel cell system with the high-voltage electrical system forms a drive system. The traction electric motor applies a driving torque to the wheels of the motor vehicle by generating a three-phase alternating current from the inverter and using this three-phase alternating current to drive the traction electric motor.

The drive system has the cooling system with the cooling circuit with a coolant line, a heat exchanger, a fan for conveying cooling air through the heat exchanger and a pump for circulating the coolant in the cooling circuit. The generally complicated and complex speed-controlled fan as a radial fan is arranged in the direction of flow of the cooling air near the rear of the heat exchanger. The cooling air passed through the heat exchanger then flows into the engine compartment of the motor vehicle and also flows around the fuel cell unit, for example. However, the engine compartment of the motor vehicle has a large flow resistance for the cooling air, so that disadvantageously both a large electrical drive power is necessary for the fan and the motor vehicle has a large air resistance due to the large flow resistance of the cooling air passed through the heat exchanger. The large diameter of the fan's rotor blades causes high noise and vibration emissions and low aerodynamic efficiency. To expel the cooling air from the engine compartment, larger openings are necessary into the environment, so that complete encapsulation or sealing of the engine compartment is not possible. The disadvantage is that dirt particles get into the engine compartment and can cause damage.

The EP 2 704 240 B1 shows a hydrogen fuel cell that uses air instead of water to cool the hydrogen fuel cells. The air is passed through a pipe system using a fan.

The DE 100 47 138 B4 shows a cooling fan system for a vehicle with a fuel cell drive, in which air can be moved through a heat exchanger for cooling purposes by means of at least one fan designed as a cooling fan and can then be supplied to the ambient air either directly or indirectly after fulfilling one or more further cooling tasks, an air branching device being provided is which supplies at least part of the air supplied by the fan or each fan to a line and thereby enables the use of the diverted air for starting the fuel cells, and wherein the fan or each fan is connected to the heat exchanger by means of a housing which prevents air losses. The blower for passing air through a heat exchanger is used in addition to compressing the ambient air as an oxidizer when starting the fuel cell unit.

The JP 2011 025 861 A an electrically powered wheelchair. The electrical energy to drive the wheelchair is generated using a fuel cell unit. The wheelchair has a heat exchanger to cool the fuel cells and a fan to direct air through the heat exchanger. The cooling air is passed through a housing which is attached to a support frame.

Disclosure of the invention

Advantages of the invention

Method according to the invention for operating a cooling system for cooling at least one component of a drive system with a traction electric motor for a motor vehicle with the steps: Conducting coolant through a coolant circuit filled with coolant with at least one coolant line and a heat exchanger by conveying the coolant through the cooling circuit with a coolant conveying device , Conducting cooling air through the heat exchanger by conveying the cooling air through the heat exchanger with a cooling air conveying device, transferring heat from the coolant conducted through the heat exchanger to the cooling air conducted through the heat exchanger, Conducting the cooling air conducted through the heat exchanger through at least one air line, where the flow resistance of the cooling air conducted through the heat exchanger is controlled and/or regulated depending on the requested braking power of the motor vehicle. The flow resistance of the cooling air passed through the heat exchanger can thus be adapted and optimized to different requirements and parameters, for example to support the friction brakes as a dynamic brake and/or to control and/or regulate the temperature of the coolant of the cooling circuit and/or to reduce the air resistance of the motor vehicle. The temperature of the coolant of the cooling circuit can be controlled and/or regulated by means of the volume flow of the coolant passed through the heat exchanger, because the larger the volume flow of the coolant passed through the heat exchanger, the greater the amount of heat transferred from the coolant to the cooling air per unit of time , d. H. the thermal heat output of the heat exchanger.

In a further variant, when the braking power of the motor vehicle is requested, the flow resistance of the cooling air conducted through the heat exchanger is increased and, due to the increased flow resistance, the air resistance of the motor vehicle is increased, so that the cooling system acts as a dynamic brake. The wear on the friction brakes can be reduced because the dynamic brake can make a significant contribution to the braking performance, particularly when the required braking power is smaller.

The greater a requested braking power of the motor vehicle, preferably the greater the flow resistance of the cooling air conducted through the heat exchanger is controlled and / or regulated and vice versa. By increasing the flow resistance of the cooling air passed through the heat exchanger, the air resistance of the motor vehicle is increased and thus the braking performance of the dynamic brake is also increased.

In a further embodiment, from reaching or exceeding a predetermined limit temperature of the coolant in the coolant circuit with a requested braking power of the motor vehicle, no increase in the flow resistance of the cooling air passed through the heat exchanger is carried out. However, the increase in the flow resistance of the cooling air conducted through the heat exchanger results in a smaller or no volume flow of cooling air being conducted through the heat exchanger and thus the thermal output of the heat exchanger is reduced. However, the temperature of the coolant in the cooling circuit must not exceed a predetermined limit value, so that once a predetermined limit temperature of the coolant in the coolant is reached or exceeded when the braking power of the motor vehicle is requested, no increase in the flow resistance of the cooling air conducted through the heat exchanger is carried out.

In an additional embodiment, the flow resistance of the cooling air conducted through the heat exchanger is changed by changing the at least one flow cross-sectional area for the cooling air on the at least one device using at least one device for changing the flow cross-sectional area for the cooling air, which is arranged within the at least one air line .

In a further embodiment, the flow resistance of the cooling air conducted through the heat exchanger is increased by reducing the at least one flow cross-sectional area for the cooling air on the at least one device with the at least one device for changing the flow cross-sectional area for the cooling air, which is arranged within the at least one air line will and vice versa.

In a further variant, the at least one device for changing the flow cross-sectional area for the cooling air is designed as at least one air flap.

Preferably, the cooling air conducted through at least one heat exchanger is conducted through at least two air lines and in a few No cooling air conveying device is arranged in at least one of the at least two air lines, so that when the at least one device for changing the at least one flow cross-sectional area for the cooling air is completely open, the flow resistance of the cooling air guided through the heat exchanger is minimal, preferably all of the at least one device for changing the at least one flow cross-sectional area is completely open. When the cooling air is routed through at least two air lines, in which at least one air line has no cooling air conveying device, the at least one air line without a cooling air conveying device has a smaller flow resistance than the at least one air line with the cooling air conveying device. When the at least one cooling air delivery device is completely open, the at least two air lines have a total of minimal flow resistance and thus the motor vehicle has a minimal air resistance. With a sufficient driving speed of the motor vehicle and a temperature of the coolant at which activation of the at least one cooling air conveying device is not necessary, the electrical energy for driving the at least one cooling air conveying device can be advantageously saved and, in addition, the motor vehicle has minimal air resistance .

In a further embodiment, the friction brakes of the motor vehicle are additionally activated once a predetermined limit value of the requested braking power of the motor vehicle is reached or exceeded. When the specified requested limit value of the motor vehicle's braking power is reached or exceeded, the maximum braking power that can be carried out by the accumulation brake is not sufficient, so that the motor vehicle's friction brakes must also be activated.

In an additional embodiment, the method described in this patent application includes a cooling system for cooling at least one component of a drive system with a traction electric motor for a motor vehicle, comprising a coolant circuit filled with coolant with at least one coolant line, a heat exchanger through which coolant flows for transferring heat from the Coolant to cooling air, a coolant conveying device for conveying coolant through the coolant circuit, a cooling air conveying device for cooling air for conveying cooling air through the heat exchanger, an air line for passing cooling air through, so that the cooling air passed through the heat exchanger can be conducted through the air line, wherein at least one Heat exchanger for transferring heat from the coolant to cooling air and / or at least one cooling air conveying device for the cooling air is arranged within at least one air line.

Cooling system according to the invention for cooling at least one component of a drive system with a traction electric motor for a motor vehicle, comprising a coolant circuit filled with coolant with at least one coolant line, a heat exchanger through which coolant flows for transferring heat from the coolant to cooling air, a coolant conveying device for conveying coolant through the Coolant circuit, a cooling air conveying device for cooling air for conveying cooling air through the heat exchanger, an air line for passing cooling air through, so that the cooling air passed through the heat exchanger can be conducted through the air line, with the cooling system being able to carry out a method described in this patent application.

In a further variant, at least one heat exchanger for transferring heat from the coolant to cooling air and/or at least one cooling air delivery device for the cooling air is arranged within at least one air line. The cooling system can thus be structurally flexibly adapted to the requirements of a motor vehicle, particularly with regard to the installation space and topology.

In a further variant, the length of the at least one air line is greater than 2, 3, 5, 7 or 10 times the, in particular minimum or maximum, diameter of the at least one air line. Preferably, within the meaning of this patent application, the term air duct requires that the length of the at least one air duct is greater than 2, 3, 5, 7 or 10 times the, in particular minimum or maximum, diameter of the at least one air duct .

Drive system according to the invention for a motor vehicle, comprising an energy source for electrical energy with a fuel cell system with a fuel cell unit and / or with a traction battery, a high-voltage electrical system with a traction electric motor and an inverter, a cooling system for cooling at least one component of the drive system, comprising a coolant filled Coolant circuit with at least one coolant line, a heat exchanger through which coolant flows for transferring heat from the coolant to cooling air, a coolant conveying device for conveying coolant through the coolant circuit, a cooling air conveying device for cooling air for conveying cooling air through the heat exchanger, the cooling system as one in this property rights The cooling system described in the application is designed and/or a method described in this patent application can be carried out with the drive system.

Motor vehicle according to the invention, comprising a body, a plurality of wheels, a drive system, wherein the drive system is designed as a drive system described in this patent application and/or a method described in this patent application can be carried out with the motor vehicle.

In a further embodiment, the method described in this patent application is carried out with the drive system and/or motor vehicle described in this patent application.

In a supplementary variant, a method described in this patent application can be carried out using the drive system and/or motor vehicle described in this patent application.

In an additional variant, at least 50%, 70%, 90% or 98%, in particular completely, of the volume flow of cooling air conducted through the at least one heat exchanger is conducted through the at least one air line.

In a further variant, the conduction of cooling air through the at least one heat exchanger is carried out in that, due to a dynamic pressure at at least one inlet opening of the at least one air line, a greater pressure is present at the at least one inlet opening of the at least one air line than at at least one while the motor vehicle is traveling Outlet opening of the at least one air line, so that the cooling air is passed through the at least one heat exchanger due to this pressure difference between the at least one inlet opening and the at least one outlet opening of the at least one air line.

In a further variant, the length of the at least one air line is greater than 2, 3, 5, 7 or 10 times the, in particular minimum or maximum, diameter of the at least one air line. Preferably, within the meaning of this patent application, the term air duct requires that the length of the at least one air duct is greater than 2, 3, 5, 7 or 10 times the, in particular minimum or maximum, diameter of the at least one air duct .

In a supplementary embodiment, the length of the at least one air line between the at least one heat exchanger and the at least one cooling air conveying device is greater than 1, 2, 3, 5 or 7 times the, in particular minimum or maximum, diameter of the at least one Air line. The at least one heat exchanger is thus evenly flowed through by cooling air, even if the sum of the at least one flow cross-sectional area of the at least one cooling air conveying device in operation is smaller than the sum of the at least one flow cross-sectional area of the at least one heat exchanger.

In a further variant, the sum of the at least one flow cross-sectional area of the at least one cooling air conveying device is greater than 1, 2, 3, 5 or 7 times the sum of the at least one flow cross-sectional area of the at least one heat exchanger. The cooling air conveying devices can therefore be designed to be particularly efficient and powerful. A sum with only one addend is also considered a sum, i.e. H. For example, only a cooling air delivery device with only one flow cross-sectional area is considered as a sum.

In a further embodiment, at least one device for changing the flow cross-sectional area for the cooling air is installed in the at least one air line on the at least one device for controlling and / or regulating the temperature of the coolant.

In a further variant, once the coolant in the coolant circuit reaches or falls below a predetermined second temperature, the flow cross-sectional area can be reduced using the at least one device for changing the flow cross-sectional area for the cooling air on the at least one device.

In an additional embodiment, several heat exchangers are arranged in the at least one air line. The multiple heat exchangers can be designed to be optimized with regard to the installation space and topology of the motor vehicle, i.e. H. the sum of the necessary flow cross-sectional areas can be divided into several smaller heat exchangers.

The plurality of heat exchangers are expediently arranged in one air line and/or are distributed over several air lines.

In a supplementary embodiment, several cooling air delivery devices are arranged in the at least one air line. The several cooling air conveying devices can be designed to be optimized with regard to the installation space and the topology, ie the sum of the necessary flow cross-sections Cutting areas can be divided into several smaller cooling air conveying devices.

In particular, the plurality of cooling air conveying devices are each arranged in one air line and/or are arranged distributed over several air lines.

In a further embodiment, the volume flow of the cooling air that can be conducted through the at least one heat exchanger can be controlled and/or regulated by controlling and/or regulating the number of cooling air conveying devices in operation. The cooling air conveying devices are preferably designed to be switched on or off without variable power control, i.e. H. are simple, inexpensive and reliable and are used in operation, i.e. H. the switched-on state, operated at an optimal operating point. This means that electrical energy for operating the cooling air conveying devices can be saved.

In a further embodiment, the at least one component cooled by the cooling system is a fuel cell unit and/or a traction battery and/or an inverter for the traction electric motor.

In a supplementary variant, at least one indirect or direct inlet opening for the at least one air line is formed at a front end region of the motor vehicle, so that a dynamic pressure can be generated in the at least one air line with the wind while the motor vehicle is driving.

In a supplementary embodiment, the front end region of the motor vehicle is an end region of the motor vehicle in the longitudinal direction of the motor vehicle, the extent of which in the longitudinal direction of the motor vehicle, starting with a front end of the motor vehicle, is less than 30%, 20% or 10% of the entire length of the motor vehicle.

The at least one air line is expediently designed to be circular and/or elliptical and/or rectangular, in particular square, in cross section. The cross-sectional shape of the at least one air line can be designed in any way and can therefore be optimally adapted to the available installation space.

In an additional variant, at least 50%, 70%, 90% or 98%, in particular completely, of the volume flow of cooling air conducted through the at least one heat exchanger can be conducted through the at least one air line.

In a further embodiment, the device for changing the flow cross-sectional area for the cooling air is designed as at least one air flap.

In a further variant, once the coolant in the coolant circuit reaches or falls below a predetermined first temperature, at least one cooling air delivery device can be switched off and/or the speed can be reduced.

In a further variant, once a predetermined first temperature of the coolant in the coolant circuit is exceeded, at least one cooling air delivery device can be switched on and/or the speed can be increased.

Preferably, with the device for changing the flow cross-sectional area for the cooling air, the flow cross-sectional area can be changed by at least 50%, 70% or 90%.

In a further variant, once a predetermined second temperature of the coolant in the coolant circuit is exceeded, the flow cross-sectional area can be increased on the at least one device using at least one device for changing the flow cross-sectional area for the cooling air.

The second temperature of the coolant is expediently smaller than the first temperature of the coolant.

In a further embodiment, the at least one cooling air conveying device is arranged in front of and/or after the at least one heat exchanger in the flow direction of the cooling air.

In a supplementary embodiment, the length of the at least one air line in the flow direction of the cooling air in front of the at least one heat exchanger is greater than 0.5, 1, 2, 3, 5 or 7 times the, in particular minimum or maximum, Diameter of the at least one air line.

In an additional embodiment, the length of the at least one air line in the flow direction of the cooling air after the at least one heat exchanger is greater than 0.5, 1, 2, 3, 5 or 7 times the, in particular minimum or maximum , diameter of the at least one air line.

In a further embodiment, the length of the at least one air line in the flow direction of the cooling air in front of the at least one cooling air conveying device for cooling air is greater than 0.5. 1, 2, 3, 5 or 7 times the, esp special minimum or maximum diameter of the at least one air line.

In a supplementary variant, the length of the at least one air line in the flow direction of the cooling air after the at least one cooling air conveying device for cooling air is greater than 0.5, 1, 2, 3, 5 or 7 times the, in particular minimum or maximum diameter of the at least one air line.

In a further embodiment, all heat exchangers for transferring heat from the coolant to cooling air and/or all cooling air conveying devices for the cooling air are arranged within at least one air line.

In a further embodiment, the motor vehicle is a passenger car or a truck.

In an additional variant, the at least cooling air delivery device comprises an electric motor.

In a further embodiment, a device for preventing a backflow of cooling air is formed on each cooling air conveying device. The device prevents a backflow of cooling air through the cooling conveyor device counter to the conveying direction of the cooling air conveyor device. This means that if there are several cooling conveyors in an air line, a backflow of cooling air in a non-operated cooling air conveyor can be avoided.

The device for preventing a backflow of cooling air is expediently designed as a blind or a check valve.

In a further variant, the blind is actively movable with an actuator and/or is movable by means of gravity and/or by means of the force of the flow of cooling air.

In a further embodiment, the coolant delivery devices are arranged stacked within an air line, in particular in a direction essentially, preferably with a deviation of less than 30°, 20° or 10°, perpendicular to the flow direction of the cooling air in the air line with the coolant delivery devices.

In an additional variant, the motor vehicle is not a wheelchair.

In a further embodiment, the at least one air line has at least one inlet opening for cooling air and at least one outlet opening for cooling air.

The coolant delivery device is preferably a pump, in particular for a liquid, or a compressor, for example a screw compressor or a turbo compressor, in particular for a gas.

In an additional variant, the cooling air conveying device is a blower, in particular a radial blower or axial blower.

In an additional variant, at least one retaining device for preventing the ingress of parts located in the ambient air, in particular at least one grid and/or at least one sieve, is arranged on the at least one inlet opening.

In an additional embodiment, the cooling air emerging from the at least one outlet opening of the at least one air line can be diverted, in particular exclusively, into the environment.

In a further variant, the cooling air that can be conducted through the at least one air line cannot be conducted through the fuel cell stack, in particular not as an oxidizing agent, preferably not during a start of the fuel cell unit.

In a complementary variant, the fuel cell system includes a fuel cell unit, a cooling system, an oxidizer supply system and a fuel supply system.

In a further variant, the temperature of the coolant and/or recirculation fuel and/or fuel and/or oxidizing agent is controlled and/or regulated using the data from a temperature sensor.

The high-voltage electrical system preferably includes a traction battery for storing electrical energy for the traction electric motor. The traction battery is used, for example, to be able to store electrical energy in the recuperation mode of the motor vehicle and/or to provide the electrical energy necessary for starting when the fuel cell system is started.

In a further embodiment, the high-voltage electrical system includes a traction electric motor for driving the motor vehicle and the traction electric motor can be operated with electrical energy from the inverter.

In an additional embodiment, the electrical voltage of the high-voltage current is at least 50 V, 100 V, 200 V or 300 V.

In a supplementary variant, the electrical voltage of the low-voltage current is less than 15 V, 20 V, 25 V, 30 V or 50 V.

In a further embodiment, a low-voltage battery with a DC/DC conversion unit is electrically connected to two high-voltage power lines of the high-voltage system.

In a further embodiment, the fuel cells each comprise a proton exchange membrane, an anode, a cathode, at least one gas diffusion layer and at least one bipolar plate.

Preferably the fuel is hydrogen, hydrogen-rich gas, reformate gas or natural gas.

The fuel cells and/or components are expediently designed to be essentially flat and/or disk-shaped.

In a complementary variant, the oxidizing agent is air with oxygen or pure oxygen.

Preferably, the fuel cell unit is a PEM fuel cell unit with PEM fuel cells.

Computer-implemented method according to the invention comprising steps of a method described in this patent application.

The invention further comprises a computer program with program code means which are stored on a computer-readable data carrier in order to carry out a method described in this patent application when the computer program is carried out on a computer, in particular a control and/or regulating unit, or a corresponding computing unit.

Part of the invention is also a computer program product with program code means that are stored on a computer-readable data carrier in order to carry out a method described in this patent application when the computer program is carried out on a computer, in particular a control and / or regulating unit, or a corresponding computing unit.

Brief description of the drawings

• 1 eine stark vereinfachte Darstellung einer Brennstoffzelleneinheit als Brennstoffzellenstack,
• 2 ein Antriebssystem,
• 3 eine perspektivische Ansicht eines Kraftfahrzeuges,
• 4 eine stark vereinfachte Darstellung eines Kühlsystems in einem ersten Ausführungsbeispiel,
• 5 eine stark vereinfachte Darstellung des Kühlsystems in einem zweiten Ausführungsbeispiel,
• 6 eine stark vereinfachte Darstellung des Kühlsystems in einem dritten Ausführungsbeispiel,
• 7 eine stark vereinfachte Darstellung des Kühlsystems in einem vierten Ausführungsbeispiel,
• 8 eine stark vereinfachte Darstellung des Kühlsystems in einem fünften Ausführungsbeispiel,
• 9 eine stark vereinfachte Darstellung des Kühlsystems in einem sechsten Ausführungsbeispiel,
• 10 eine stark vereinfachte Darstellung des Kühlsystems in einem siebten Ausführungsbeispiel,
• 11 eine stark vereinfachte Darstellung des Kühlsystems in einem achten Ausführungsbeispiel,
• 12 eine stark vereinfachte Darstellung des Kühlsystems in einem neunten Ausführungsbeispiel,
• 13 eine stark vereinfachte Darstellung des Kühlsystems in einem zehnten Ausführungsbeispiel,
• 14 einen Schnitt durch ein Gebläse mit geöffneten Jalousien und
• 15 einen Schnitt durch das Gebläse gemäß 14 mit geschlossenen Jalousien.

Exemplary embodiments of the invention are described in more detail below with reference to the accompanying drawings. It shows:

• 1 a greatly simplified representation of a fuel cell unit as a fuel cell stack,
• 2 a drive system,
• 3 a perspective view of a motor vehicle,
• 4 a greatly simplified representation of a cooling system in a first exemplary embodiment,
• 5 a greatly simplified representation of the cooling system in a second exemplary embodiment,
• 6 a greatly simplified representation of the cooling system in a third exemplary embodiment,
• 7 a greatly simplified representation of the cooling system in a fourth exemplary embodiment,
• 8th a greatly simplified representation of the cooling system in a fifth exemplary embodiment,
• 9 a greatly simplified representation of the cooling system in a sixth exemplary embodiment,
• 10 a greatly simplified representation of the cooling system in a seventh exemplary embodiment,
• 11 a greatly simplified representation of the cooling system in an eighth exemplary embodiment,
• 12 a greatly simplified representation of the cooling system in a ninth exemplary embodiment,
• 13 a greatly simplified representation of the cooling system in a tenth exemplary embodiment,
• 14 a section through a fan with the blinds open and
• 15 a section through the fan 14 with closed blinds.

In 1 a fuel cell unit 10 is shown as a fuel cell stack 11, ie as a fuel cell stack 11. The fuel cell unit 10 includes the fuel cell stack 11, a housing (not shown) and a connection plate (not shown). In the fuel cell stack 11 Fuel cells 12 are stacked as PEM fuel cells 13 and arranged in alignment. Due to the large number of stacked fuel cells 12 of approximately 300 to 400 fuel cells 12, these are in 1 Not all are shown for reasons of simplicity. The principle of fuel cells 12 is that electrical energy or electrical current is generated by means of an electrochemical reaction. Hydrogen H ₂ is passed to an anode as gaseous fuel and the anode forms the negative pole. A gaseous oxidizing agent, namely air with oxygen, is passed to a cathode (not shown), ie the oxygen in the air provides the necessary gaseous oxidizing agent. A reduction (acquisition of electrons) takes place at the cathode. The oxidation as electron release is carried out at the anode. The fuel cell 12 also includes a proton exchange membrane (PEM) arranged between the anode and the cathode. The electrodes as the anode and cathode (not shown) lie on both sides of the PEM, each facing the gas spaces. A unit consisting of the PEM and anode and cathode is called a membrane electrode assembly (MEA) (not shown). A gas diffusion layer (GDL) lies on the anode and cathode. A bipolar plate (not shown) rests on the GDL. The electrically conductive bipolar plate serves as a current collector, for draining water and for conducting the reaction gases

In 3 a motor vehicle 1 is shown. The motor vehicle 1 comes with an in 2 Drive system 4 shown is driven and delayed, ie braked. The motor vehicle 1 has four wheels 2, 2 of which are driven. The 2 driven wheels 2 ( 2 ) are driven by a gearbox 3 and a traction electric motor 50.

This in 2 Drive system 4 shown includes a fuel cell system 9 with the fuel cell unit 10, a high-voltage electrical system 7 and a low-voltage electrical system 8.

In addition to the fuel cell unit 10, the fuel cell system 9 includes an oxidant supply system 55 for supplying the fuel cell stack 11 with air as an oxidant, namely a gas delivery device 14, for example a blower 15, a compressor 16 or a turbo compressor 17, which is driven by an electric motor 18, a supply line 19 for oxidizing agent, a bypass line 20 for oxidizing agent, a heat exchanger 21 for the oxidizing agent, an air filter 22 and valves 23 for the oxidizing agent. In the oxidant supply system 55 for supplying the fuel cell stack 11 with air, ambient air is sucked in through the air filter 22 by means of the gas delivery device 14, which is driven by the electric motor 18. After the ambient air has been compressed in the gas conveying device 14, it is cooled with the heat exchanger 21 and then fed to the fuel cell stack 11 through the supply line 19. By means of the valves 23, the ambient air compressed by the gas conveying device 14 can be partially or completely passed through the bypass line 20 and then discharged into the environment without passing through the fuel cell stack 11. The valves 23 thus also control the volume flow of the oxidizing agent derived through the fuel cell stack 11. A temperature sensor 52 detects the temperature of the oxidizing agent discharged from the fuel cell stack 11.

In addition to the fuel cell unit 10, the fuel cell system 9 also includes a fuel supply system 54 for supplying the fuel cell stack 11 with hydrogen as fuel, namely a pressure vessel 24, a fuel line 25, valves 26 for fuel, a heat exchanger 27 for fuel, a pressure reducer 28, a recirculation fuel line 29, a recirculation fuel conveyor 30, an electric motor 31 for driving the recirculation fuel conveyor 31, a jet pump 32, a water separator 33 for separating water from the recirculation fuel, a water container 34 for collecting the water collected in the water separator 33, a drain valve 35 for draining water from the Water tank 34 and a drain valve 36 as a purge valve 36 for draining recirculation fuel into the environment. In the fuel supply system 54 for supplying the fuel cell stack 11 with hydrogen as fuel, the hydrogen stored in the pressure vessel 24 at a high pressure of, for example, 400 bar is supplied to the fuel cells 12 through the fuel line 25 and is tempered by means of the heat exchanger 27 and relaxed by means of the pressure reducer 28 , that is, the pressure is reduced. After the fuel has been passed through the fuel cells 12, the hydrogen is not completely consumed, so that this hydrogen derived from the fuel cells 12 is fed back to the fuel cells 12 in a circuit through the recirculation fuel line 29. To convey the recirculation fuel through the recirculation fuel line 29, the recirculation fuel conveying device 30 is used, which is driven by the electric motor 31. After the fuel has been passed through the fuel cells 12, the moisture content of the fuel increases, so that in order to avoid excessive water or moisture content in the recirculation fuel Fuel supply system 54 has the water separator 33. The water separated in the water separator 33 is collected in the water container 34 and discharged into the environment through the drain valve 35. Excess recirculation fuel is discharged into the environment through the drain valve 36.

In addition to the fuel cell unit 10, the fuel cell system 9 also includes a cooling system 53 for controlling the temperature of the fuel cell stack 11, i.e. H. for cooling the fuel cell stack 11. The cooling system 53 for controlling the temperature of the fuel cell stack 11 comprises a coolant line 37, a 3-way valve 38, a heat exchanger 39, a blower 40 as a cooling air conveying device 5 for the heat exchanger 39, an electric motor 41 for driving the blower 40, a coolant pump 42 as a coolant delivery device 56 and an electric motor 43 for driving the coolant pump 42. Coolant as a fluid, for example water with antifreeze or a gas, for example air, is passed through a circuit with the coolant line 37. In the fuel cell unit 10 with the fuel cells 12, channels for coolant are formed between the bipolar plates. In these channels for coolant between the bipolar plates (not shown), the coolant absorbs the heat that occurs during the electrochemical reaction and is then passed through the heat exchanger 39. This allows, for example, the operating temperature of the fuel cell stack 11 to be regulated to 60 ° C. By means of the blower 40, ambient air is passed through the heat exchanger 39, so that the heat from the fuel cell unit 10 is released into the environment. The pump 42 delivers the coolant through the coolant circuit. A temperature sensor 52 in the coolant circuit detects the temperature of the coolant circuit. The temperature in the coolant circuit is controlled and/or regulated by controlling and/or regulating the electrical power of the electric motors 41, 43 with a control and/or regulating unit, not shown. Increasing the electrical rating of the electric motors 41, 43 increases the thermal power on the heat exchanger 39 to release heat to the ambient air and vice versa. In addition, the temperature in the coolant circuit can be controlled and/or regulated by using the 3-way valve 38 to control and/or regulate the volume flow of the coolant passed through the heat exchanger 39.

The high-voltage electrical system 7 includes high-voltage power lines 44, a DC/DC conversion unit 46 for the high-voltage power line 44, the traction battery 48 and an inverter 51 for the traction electric motor 50. The direct current generated in the fuel cell stack 11 is converted to a DC/DC conversion unit 46 constant DC voltage of, for example, 400 V for cars and 800 V for trucks. This means that there is a substantially constant direct voltage in the high-voltage electrical system 7. In the fuel cell unit 10, the DC voltage provided corresponds approximately to the number of fuel cells 12 multiplied by approximately 1 V, so that, for example, in a fuel cell unit 1 with 300 fuel cells 12, the DC voltage is 300 V. The electrical energy for driving the traction electric motor 50 is conducted through the high-voltage power lines 44 from the traction battery 48 and/or from the fuel cell stack 11 to the inverter 51. A three-phase alternating current is generated in the inverter 51 and this is used to drive the traction electric motor 50. The traction electric motor can also be operated in recuperation mode.

The low-voltage electrical system 8 includes the DC/DC conversion unit 47, a low-voltage power line 45 and the low-voltage battery 49. In the DC/DC conversion unit 47, the direct current in the high-voltage power line 44 is reduced to a voltage of, for example, 12 V or 24 V and in the Low-voltage battery 49 stored. Using the low-voltage battery 49, consumers (not shown) are operated with an operating voltage of, for example, 12 V or 24 V, for example a windshield wiper motor, lighting devices and electric motors for the air conditioning system. These electrical consumers (not shown), which are operated with low voltage, are also part of the low-voltage system 8. An electrical system 6 thus includes the high-voltage electrical system 7 and the low-voltage electrical system 8.

In 2 the basic structure of the entire drive system 4 is shown without an air line 57 being shown. In the cooling system 53, ambient air is sucked in by the fan 40, passed through the heat exchanger 39 as cooling air and, in addition, this ambient air is also passed through at least one in 2 Air line 57, not shown. In the 4 to 13 Various exemplary embodiments for the conduction of cooling air through the air line 57 and without an illustration of the cooling circuit with the coolant line 37 are shown. In these exemplary embodiments, the cooling air conveying device 5 and/or the heat exchanger 39 is additionally arranged within the at least one air line 57.

In 4 a first exemplary embodiment of the cooling system 53 is shown. After passing through the heat exchanger 39, the cooling air passed through the heat exchanger 39 is passed into a collecting housing 65 and then connected ßend passed through the air line 57. The collecting housing 65 has an inlet opening 72 for cooling air and the heat exchanger 39 is arranged at this inlet opening 72. The direct inlet opening 72 for the collecting housing 72 forms an indirect inlet opening 61 for the air line 57 because the cooling air flows from the collecting housing 65 into the air line 57. The cooling air conveying device 5 as the blower 40 is arranged within the air line 57. The air line 57 has a first end 59 as an inlet opening 61 and a second end 60 as an outlet opening 62 for the cooling air. The inlet opening 61 opens into the collecting housing 65. The outlet opening 62 as the second end 60 opens into the environment. The air line 57 has a diameter 66.

The length of the air line 57 from the first end 59 as the inlet opening 61 to the outlet opening 62 as the second end 60 is many times larger, for example at least 10 times, than the diameter 66 of the air line 57. An air line 57 within the meaning of this patent application has a length that is at least 2 times, 3 times or 5 times larger than the, in particular minimum or maximum, diameter 66 of the air line 57. The length of the air line 57 in the flow direction of the cooling air the fan 40 to the inlet opening 61 and the outlet opening 62 is at least 3 times the diameter 66 of the air line 57. The diameter 66 is the inside diameter of the air line 57. The formation of the fan 40 within the air line 57 has the advantage that Diameter of the blower 40 when the blower 40 is designed as a radial blower 40 is small and therefore small speeds occur at the end of the rotor blades of the radial blower 40 and therefore the blower 40 is aerodynamically efficient due to the small diameter, i.e. h a low electrical drive power is required for a certain volume flow. Due to the arrangement of the blower 40 within the air line 57, the noise emissions decrease and, furthermore, the heat exchanger 39 advantageously flows through the heat exchanger 39 with a substantially uniform volume flow per unit area of cooling air distributed over the cross-sectional area of the heat exchanger 39. The fuel cell system 9 and preferably also the drive system 4 can be sealed and encapsulated with respect to the environment because the cooling air is passed through the air line 57 past the fuel cell stack 11, so that no protective particles penetrate into the engine compartment and the fuel cell system 9 heats up quickly during a cold start and only cools down slowly after a stop.

The heat exchanger 39 is formed at a front end region of the motor vehicle 1 and the outlet opening 62 is arranged at any location on the motor vehicle 1. This means that the cooling air can be guided through the air line 57 in a flexible and optimized manner within this motor vehicle 1 in accordance with the design requirements of the motor vehicle. The cooling air can be passed through the air line 57 without pneumatic obstacles due to the optimized design of the air line 57, so that a low electrical power is required to drive the fan 40 and the air resistance of the motor vehicle 1 is reduced, so that the traction electric motor 50 requires little electrical drive energy needed.

In 5 a second exemplary embodiment of the cooling system 53 is shown. Essentially only the differences from the first exemplary embodiment are described below 4 described. An air flap 64 is additionally arranged within the air line 57 as a device 63 for changing the flow cross-sectional area of the air line 57. With the device 63, the flow cross-sectional area can be changed between a maximum flow cross-sectional area, which corresponds to the flow cross-sectional area of the air line 57, and a minimum flow cross-sectional area of 0, ie the air line 57 is completely closed at the flow cross-sectional area of 0. While driving the motor vehicle 1, it is necessary to brake the motor vehicle 1 using vehicle brakes, for example disc brakes or drum brakes. When the air flap 64 is completely closed, the air resistance of the motor vehicle 1 increases, so that during a braking process of the motor vehicle 1, the air flap 64 is closed by a control and / or regulation unit, not shown, to support the vehicle brakes as a storage brake. After the braking process has ended, the air flap 64 is fully opened again. This can reduce mechanical wear on the vehicle brakes. In addition, the thermal output of the heat exchanger 39 can also be controlled and/or regulated with the air flap 64. From a certain speed of the motor vehicle 1, the dynamic pressure on the heat exchanger 1 due to the wind is sufficient to generate a sufficient volume flow of cooling air through the heat exchanger 39 and the air line 57 without operating the cooling air conveying device 5, so that it can be switched off. If the speed of the motor vehicle 1 increases further and with it the volume flow of the cooling air through the heat exchanger 39, the thermal power can be reduced by reducing the volume flow of the cooling air that is passed through the heat exchanger 39 using the device 63 by reducing the flow cross-sectional area The heat exchanger 39 can be controlled and/or regulated to transfer heat from the coolant to the cooling air. This means that the temperature of the coolant in the cooling circuit can be controlled and/or regulated using a further parameter.

In 6 a third exemplary embodiment of the cooling system 53 is shown. Essentially only the differences from the first exemplary embodiment are described below 4 described. The cooling system 53 has 2 air lines 57. A first, in 6 The air line 57 shown above has the cooling air conveying device 5 and a second air line 57 with the device 63 for changing the flow cross-sectional area of the air line 57 branches off from this first air line 57 at a junction 58. When the air flap 64 is fully open, the cooling air conducted through the heat exchanger 39 and the collecting housing 65 can be discharged into the environment through 2 air lines 57 with 2 outlet openings 62. There is no fan 40 in the second, lower air line 57, so that the cooling air can be passed through the second lower air line 57 and thus also through the entire air lines 57 with a very low flow resistance. This means that even at low speeds of the motor vehicle 1, the dynamic pressure of the airstream is sufficient for a sufficient volume flow of cooling air to transfer heat from the coolant to the cooling air. The fan 40 can thus be switched off even at low speeds of the motor vehicle 1 and the motor vehicle 1 advantageously has a small air resistance. When the air flap 64 is completely closed, the flow resistance of the cooling air in the air line 57 is increased, so that the motor vehicle 1 can be braked and the cooling system 53 also functions as a storage brake.

In 7 a fourth exemplary embodiment of the cooling system 53 is shown. Essentially only the differences from the third exemplary embodiment are described below 6 described. In the first, upper air line 57, the device 63 for changing the flow cross-sectional area in the upper air line 57 is additionally designed as the air flap 64. When the two air flaps 64 are completely closed both in the first upper air line 57 and in the second, lower air line 57, the air resistance of the motor vehicle 1 is significantly increased, so that the cooling system 53 functions as a very effective traffic brake. When driving uphill with the motor vehicle 1 at a low speed and the volume flow of cooling air is generated through the air lines 57 with essentially the fan 40, the air flap 64 is completely closed in the lower, second air line 57 and completely opened in the first, upper air line so that there is no backflow of cooling air through the lower, second air line 57.

In 8th a fifth exemplary embodiment of the cooling system 53 is shown. Essentially only the differences from the first exemplary embodiment are described below 4 described. The heat exchanger 39 is integrated into the air line 57 as a tubular heat exchanger 69, ie is arranged within the air line 57. The inlet opening 61 as the first end 59 of the air line 57 is arranged at the front end region of the motor vehicle 1, so that the dynamic pressure of the wind of the motor vehicle 1 acts on the inlet opening 61. The diameter 66 of the air duct 57 is increased at the inlet opening 61 and a grid 71 is arranged at the inlet opening 61 as a retaining device 70 for parts in the ambient air. This can prevent small parts, such as insects or other particles, from entering the air line 57 with the grid 71. The geometry of the inlet opening 61 is completely arbitrary, that is, for example, it can also be designed to be slot-shaped or elliptical in accordance with the requirements in the motor vehicle 1. This enables a particularly effective integration of the cooling system 53 into the motor vehicle 1. In addition, the heat exchanger 39 is designed as a tubular heat exchanger 69 has a large length, for example the length of the tube heat exchanger 69 is at least 2 times, 5 times or 10 times larger than the diameter 66 of the air line 57. Due to this large area of the tube heat exchanger 69, the heat from the coolant can be particularly be transmitted effectively with a small temperature difference between the coolant and the cooling air.

In 9 a sixth exemplary embodiment of the cooling system 53 is shown. Essentially only the differences from the first exemplary embodiment are described below 4 described. Several cooling air conveying devices 5, ie a total of 5 cooling air conveying devices 5, are arranged in the air line 57. The diameter 66 of the air line 57, which is essentially rectangular in cross section, is larger at the cooling air conveying device 5 than at the inlet opening 61 with the heat exchanger 39. The flow cross-sectional area of the air line 57 is therefore also larger at the 5 cooling air conveying devices 5 than at the heat exchanger 39. The cooling air conveying devices 5 are arranged stacked on top of each other in a direction essentially perpendicular to the flow direction of the cooling air through the air line 57. The control and / or regulation of the cooling by means of the 5 Air conveying devices 5 through the air line 57 required volume flow of the cooling air can be carried out by a simple binary control and / or regulation: only the number of cooling air conveying devices 5 in operation is controlled, ie the volume flow of the volume flow of the cooling air required with the 5 cooling air conveying devices 5 is controlled and/or regulated in 5 stages. This enables particularly simple control and/or regulation. The cooling air conveying devices 5 are designed, for example, as radial fans and have rotor blades with a small diameter, so that the ends of the rotor blades of the radial fan 40 have a small rotation speed and thus the cooling air conveying devices 5 have a low energy requirement with little noise generation.

In 14 and 15 is a cut through a fan 40 each 9 shown. In the direction of flow of the cooling air through the fan 40, a device 67 for preventing a backflow of cooling air on the cooling air conveying device 5 is formed on it after the rotor blades of the cooling air conveying device 5. The device 67 is designed as a blind 68. When operating the cooling air conveying devices 5, in which at least one cooling air conveying device 5 is not in operation, a backflow of cooling air could occur through the cooling air conveying device 5 which is not in operation. To prevent this, the devices 67 are designed as blinds 68. The individual elements of the blinds 68 are pivotally mounted about a pivot axis perpendicular to the drawing plane 14 and 15 , so that when the fan 40 is in operation, the blinds 68 open due to the flow of cooling air. When the cooling air delivery device 5 is switched off, the elements of the blind 68 move due to gravity as well as due to an initial backflow of the cooling air into the in 15 closed position of the blind 68. In the closed position of the blind 68, there is no backflow of cooling air. Deviating from this, the elements of the blind 68 can also be pivoted using an electric servomotor as an actuator when the cooling air conveying device 5 is in operation 14 shown open position and with the cooling air conveyor 5 switched off in the in 15 closed position shown. Deviating from this, the devices 67 can also be designed simply as a check valve.

In 10 a seventh embodiment of the cooling system 53 is shown. Essentially only the differences to the sixth exemplary embodiment are described below 9 described. The cooling system 53 has 2 air lines 57, which end with their first ends 59 as the inlet openings 61 on a rear side of the heat exchanger 39. Two cooling air conveying devices 5 are arranged in each of these two air lines 57. The diameter 66 of the 2 air lines 57 is therefore smaller than in the sixth exemplary embodiment 9 , so that the air lines 57 can be guided through the engine compartment of the motor vehicle 1 in a structurally simpler manner with a smaller local space requirement.

In 11 an eighth embodiment of the cooling system 53 is shown. Essentially only the differences to the sixth exemplary embodiment are described below 9 described. The cooling system 3 only has one cooling air delivery device 5. The heat exchanger 39 is installed within the air line 57 with a distance between the heat exchanger 39 in the direction of flow of the cooling air through the air line 57 to both the inlet opening 61 and the outlet opening 62. The diameter of the air line 57 is larger locally in the area of the heat exchanger 39 than outside of the heat exchanger 39, so that the heat exchanger 39 has a larger flow cross-sectional area. The heat exchanger 39 can also be installed in the air line 57 in different orientations and in 11 Another option for arranging the heat exchanger 39 in the air line 57 is shown in dashed lines.

In 12 a ninth exemplary embodiment of the cooling system 53 is shown. Essentially only the differences to the eighth exemplary embodiment are described below 11 described. The cooling system 57 has 3 air lines 57, each with an inlet opening 61 at the front end region of the motor vehicle. The 3 inlet openings 61 have a small diameter 66 and can therefore be particularly easily integrated into the body at the front end area of the motor vehicle. The ambient air introduced as cooling air through the 3 inlet openings 61 into the 3 air lines 57 is collected at the junction 58 and then passed through only one air line 57 with the heat exchanger 39 and the cooling air conveying device 5. Another option for aligning the heat exchanger 39 in the air line 57 is analogous to 11 also in 12 shown in dashed lines.

In 13 a tenth exemplary embodiment of the cooling system 53 is shown. Essentially only the differences from the ninth exemplary embodiment are described below 12 described. A cooling air conveying device 5 is installed in each of the 3 air lines 57 with the 3 inlet openings 61. The cooling system 53 thus has a total of 3 cooling air conveying devices 5.

In a further exemplary embodiment, not shown, the drive system 4 is designed without the fuel cell system 9. The motor vehicle 1 with this drive system 4 is therefore powered exclusively by battery electricity. The traction battery 48 is designed to be larger and is charged from a public power grid while the motor vehicle is at a standstill. The cooling system 53 cools and tempers the traction battery 48 and the inverter 51 for the traction battery 48 in this drive system 4. A gas, for example air, can also be used as a coolant in the cooling system 53 of the cooling circuit.

Overall, there are significant advantages associated with the cooling system 53 according to the invention, the drive system 4 according to the invention and the motor vehicle 1 according to the invention. The cooling air for the heat exchanger 39 is completely passed through at least one air line 57. The cooling air therefore does not have to be passed through an engine compartment with a high flow resistance and can be passed through the at least one air line 57, which is designed to be optimized for flow technology, with a low flow resistance. This means that little electrical energy is advantageously required to drive the cooling air conveying device 5 and the motor vehicle 1 has low air resistance, i.e. H. small CW value. The arrangement of the at least one heat exchanger 39 and the at least one cooling air conveying device 5 within the at least one air line 57, i.e. H. in the flow space for cooling air limited by the air line 57, it makes it possible to flexibly adapt the cooling system 53 to the installation space requirements in a structurally optimized manner. For example, a heat exchanger 39 with a large individual flow cross-sectional area can be avoided by dividing the thermally necessary flow cross-sectional area of the heat exchanger 39 between several smaller heat exchangers 39 and this also applies analogously to the size of the cooling air conveying devices 5. In addition, several cooling air conveying devices 5 have rotor blades a smaller diameter has a higher aerodynamic efficiency, i.e. H. For the same volume flow of cooling air, they require less electrical drive power than just a cooling air conveying device 5 with rotor blades with a large diameter. The cooling system 53 can additionally function as a dynamic pressure brake by means of the device 63 for changing the flow cross-sectional area in the air line 57 and thus also support the vehicle brakes of the motor vehicle 1.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 2704240 B1 [0005]
• DE 10047138 B4 [0006]
• JP 2011025861 A [0007]

Claims (15)

Method for operating a cooling system (53) for cooling at least one component (10, 11, 48, 50, 51) of a drive system with a traction electric motor (4) for a motor vehicle (1) with the steps: - Conducting coolant through a coolant filled coolant circuit with at least one coolant line (37) and a heat exchanger (39) by conveying the coolant through the cooling circuit with a coolant conveying device (56), - passing cooling air through the heat exchanger (37) by passing the cooling air with a cooling air conveying device (5). the heat exchanger (37), - transferring heat from the coolant conducted through the heat exchanger (37) to the cooling air conducted through the heat exchanger (37), - conducting the cooling air conducted through the heat exchanger (37) through at least one air line (57 ), characterized in that the flow resistance of the cooling air conducted through the heat exchanger (37) is controlled and/or regulated depending on the requested braking power of the motor vehicle (1). Procedure according to Claim 1 , characterized in that when the braking power of the motor vehicle (1) is requested, the flow resistance of the cooling air conducted through the heat exchanger (37) is increased and due to the increased flow resistance, the air resistance of the motor vehicle (1) is increased, so that the cooling system (53) as The traffic brake works. Procedure according to Claim 1 or 2 , characterized in that the greater the requested braking power of the motor vehicle (1), the greater the flow resistance of the cooling air conducted through the heat exchanger (37) is controlled and / or regulated and vice versa. Method according to one or more of the preceding claims, characterized in that from reaching or exceeding a predetermined limit temperature of the coolant in the coolant circuit with a requested braking power of the motor vehicle (1), no increase in the flow resistance of the cooling air passed through the heat exchanger (37) is carried out . Method according to one or more of the preceding claims, characterized in that the flow resistance of the cooling air conducted through the heat exchanger (37) is changed by using at least one device (63) for changing the flow cross-sectional area for the cooling air, which is within the at least one air line (57 ) is arranged, the at least one flow cross-sectional area for the cooling air on the at least one device (63) is changed. Method according to one or more of the preceding claims, characterized in that the flow resistance of the cooling air conducted through the heat exchanger (37) is increased by using the at least one device (63) for changing the flow cross-sectional area for the cooling air, which is within the at least one air line ( 57) is arranged, the at least one flow cross-sectional area for the cooling air on the at least one device (63) is reduced and vice versa. Procedure according to Claim 5 or 6 , characterized in that the at least one device (63) for changing the flow cross-sectional area for the cooling air is designed as at least one air flap (64). Method according to one or more of the preceding claims, characterized in that the cooling air passed through at least one heat exchanger (39) is passed through at least two air lines (57) and no cooling air conveying device (5) is arranged in at least one of the at least two air lines (57). , so that when the at least one device (63) is completely open for changing the at least one flow cross-sectional area for the cooling air, the flow resistance of the cooling air guided through the heat exchanger (39) is minimal. Method according to one or more of the preceding claims, characterized in that the friction brakes of the motor vehicle (1) are additionally activated once the braking power of the motor vehicle (1) has been reached or exceeded a predetermined limit value. Method according to one or more of the preceding claims, characterized in that the method includes a cooling system (53) for cooling at least one component (10, 11, 50, 51) of a drive system (4) with a traction electric motor (50) for a motor vehicle ( 1), comprising a coolant circuit filled with coolant with at least one coolant line (37), a heat exchanger (39) through which coolant flows for transferring heat from the coolant to cooling air, a coolant conveying device (56) for conveying coolant through the coolant circuit, a cooling air conveying device (5) for cooling air for conveying cooling air through the heat exchanger (39), an air line (57) for the through conduction of cooling air, so that the cooling air conducted through the heat exchanger (39) can be conducted through the air line (57), with at least one heat exchanger (39) for transferring heat from the coolant to cooling air and / or at least one cooling air conveying device (5) for the cooling air is arranged within at least one air line (57). Cooling system (53) for cooling at least one component (10, 11, 50, 51) of a drive system (4) with a traction electric motor (50) for a motor vehicle (1), comprising - a coolant circuit filled with coolant and having at least one coolant line (37) , - a heat exchanger (39) through which coolant flows for transferring heat from the coolant to cooling air, - a coolant conveying device (56) for conveying coolant through the coolant circuit, - a cooling air conveying device (5) for cooling air for conveying cooling air through the heat exchanger ( 39), - an air line (57) for the passage of cooling air, so that the cooling air passed through the heat exchanger (39) can be conducted through the air line (57), characterized in that with the cooling system (53) a method according to one or more of the preceding claims can be carried out. cooling system Claim 11 , characterized in that at least one heat exchanger (39) for transferring heat from the coolant to cooling air and / or at least one cooling air conveying device (5) for the cooling air is arranged within at least one air line (57). cooling system Claim 11 or 12 , characterized in that the length of the at least one air line (57) is greater than 2, 3, 5, 7 or 10 times the, in particular minimum or maximum, diameter (66) of the at least one air line (57) is. Drive system (4) for a motor vehicle (1), comprising - an energy source for electrical energy with a fuel cell system (9) with a fuel cell unit (10) and/or with a traction battery (48), - an electrical high-voltage system (7) with a traction electric motor (50) and an inverter (51), - a cooling system (53) for cooling at least one component (10, 11, 50, 51) of the drive system (4), comprising a coolant circuit filled with coolant and having at least one coolant line (37), a heat exchanger (39) through which coolant flows for transferring heat from the coolant to cooling air, a coolant conveying device (56) for conveying coolant through the coolant circuit, a cooling air conveying device (5) for cooling air for conveying cooling air through the heat exchanger (39), thereby characterized in that the cooling system (53) according to one or more of the Claims 11 until 13 is trained. Motor vehicle (1), comprising - a body, - several wheels (2), - a drive system (4), characterized in that the drive system (4) according to Claim 14 is trained.

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