Method and device for detecting a malfunction of a shut-off valve of an energy converter system, energy converter system, vehicle, computer program product and storage medium

Abstract

The present invention relates to a method for detecting a malfunction of a shut-off valve (15) of an energy converter system (10), wherein the energy converter system (10) comprises an energy converter (11), a pressure vessel (12) for storing fuel, a fuel inlet path (13) for conveying fuel to the pressure vessel (12), a fuel outlet path (14) for conveying fuel from the pressure vessel (12) to the energy converter (11), and the shut-off valve (15) for preventing a backflow of fuel from the pressure vessel (12) into the fuel inlet path (13), the method comprising the steps of: identifying a fuel withdrawal operation in which fuel is conveyed from the pressure vessel (12) to the energy converter (11) for a defined period of time; identifying a fuel behavior in the fuel inlet path (13) following the identified fuel withdrawal operation; and detecting a malfunction of the shut-off valve (15) on the basis of the identified fuel behavior. The invention also relates to a device (20), to an energy converter system (10), to a vehicle (100), to a computer program product (30) for carrying out the method, and to a computer-readable storage medium (40) on which the computer program product (30) is stored.

Description

[0001] Description

[0002] Method and apparatus for detecting a malfunction of a shut-off valve of an energy converter system, energy converter system, vehicle, computer program product and storage medium

[0003] The technology disclosed herein relates to a method and a device for detecting a malfunction of a shut-off valve in an energy converter system. The technology disclosed herein further relates to an energy converter system with such a device, a computer program for executing the method, and a computer-readable storage medium on which such a computer program is stored.

[0004] Energy conversion systems such as fuel cell systems or hydrogen combustion engines are known in the prior art. In a vehicle, such energy conversion systems are configured to generate electrical energy for a vehicle's drive motor or to generate mechanical work to propel the vehicle. Typical energy conversion systems comprise an energy converter, a pressure vessel for storing fuel, a fuel inlet path for supplying fuel to the pressure vessel, a fuel outlet path for supplying fuel from the pressure vessel to the energy converter, and various valves for controlling and regulating the fuel flow within the energy conversion system. A valve assembly with various valves is generally installed on the pressure vessel, through which the fuel flow into and out of the pressure vessel is controlled and / or regulated.A further valve is often arranged at a fuel inlet of the fuel inlet path, which prevents unintentional backflow of fuel from the fuel inlet path into the environment of the energy converter system. In known energy converter systems, the valve arrangement on the pressure vessel includes a check valve to prevent backflow of fuel from the pressure vessel into the fuel inlet path.

[0005] Numerous methods and devices for detecting potential fuel leaks in the fuel inlet and / or outlet paths are proposed in the prior art. For example, it is known to determine the amount of fuel supplied through the fuel inlet path and the amount of fuel consumed in a fuel cell and to infer a possible fuel leak based on the difference between these fuel quantities and a reference value. Furthermore, methods and devices are known in which the cumulative fuel consumption from a pressure vessel is determined over a selected period, and a change in the fluid volume within the pressure vessel is then determined to infer a fuel leak based on a potentially excessive change in the fluid volume.Due to the constant pressure equalization between the pressure vessel and the fuel inlet path, leakage diagnosis is complicated. Current methods and devices for detecting potential faults in the shut-off valve are limited to the mechanical inspection of the valve. Methods and devices for verifying mechanical integrity are expensive and require valuable installation space.

[0006] The purpose of the present technology is to create improved methods and devices for detecting a possible malfunction of a shut-off valve and / or an internal fuel leakage of an energy converter system.

[0007] The aforementioned problem is solved by the claims. In particular, the aforementioned problem is solved by the method according to claim 1 and by the device, the energy conversion system, the vehicle, the computer program product, and the computer-readable storage medium according to the dependent claims. Further advantages of the disclosed technology will become apparent from the subclaims, the description, and the figures. Features described in connection with the method also apply in connection with the device, the energy conversion system, the vehicle, the computer program product, and the storage medium, and vice versa, so that the disclosure always makes and / or can make reciprocal references to the individual aspects.

[0008] According to a first aspect of the present technology, a method for detecting a malfunction of a shut-off valve in an energy converter system is proposed, wherein the energy converter system comprises an energy converter, a pressure vessel for storing fuel, a fuel inlet path for directing fuel to the pressure vessel, a fuel outlet path for directing fuel from the pressure vessel to the energy converter, and the shut-off valve for preventing backflow of fuel from the pressure vessel into the fuel inlet path. The method comprises the following steps:

[0009] - Detecting a fuel withdrawal operation in which fuel is directed from the pressure vessel to the energy converter for a defined period of time, - Determining the fuel behavior in the fuel inlet path following the detected fuel withdrawal operation and

[0010] - Detecting the malfunction of the shut-off valve based on the determined fuel behavior.

[0011] Within the framework of the technology described here, it was discovered that the functionality of the shut-off valve can be inferred from the relationship between fuel withdrawal operation over a defined period and the subsequent fuel behavior in the fuel inlet path. During fuel withdrawal, the fuel in the pressure vessel cools down. Following fuel withdrawal, the pressure vessel, and thus the fuel within it, can heat up again. This leads to a pressure increase in the pressure vessel. Depending on the operating state of the shut-off valve, this pressure increase can have varying effects on the fuel behavior in the fuel inlet path. Therefore, the operating state of the shut-off valve can be inferred from the fuel behavior in the fuel inlet path following a specific fuel withdrawal operation.Such a procedure can be implemented simply and in a space-saving manner. In particular, measuring and / or calculating instruments that are already present in conventional energy conversion systems can be used for the process.

[0012] Detecting a malfunction based on the determined fuel behavior can mean either identifying the presence of a malfunction or confirming that the shut-off valve is functioning correctly. This can be achieved by comparing the determined fuel behavior with a reference fuel behavior. The malfunction can then be detected based on this comparison.

[0013] The term "shut-off valve" can refer to either a passive or an active shut-off valve. It can be configured as a check valve. A shut-off valve can be understood as a primary shut-off valve located on and / or near a pressure vessel. It can also refer to the primary shut-off valve of a valve assembly integrated into the pressure vessel. This assembly can be configured to control and / or regulate fuel flow into and / or out of the pressure vessel and may include additional valves. The shut-off valve should be distinguished, in particular, from a secondary shut-off valve that may be positioned in conventional energy converter systems and / or in the energy converter system described here, near a fuel inlet of the fuel inlet path.

[0014] The term "energy converter system" can refer to a fuel cell system. In this case, the energy converter can be understood to be at least one fuel cell or a fuel cell stack. The term "energy converter system" can also refer to an internal combustion engine system. In this case, the energy converter can be understood to be an internal combustion engine. The internal combustion engine can be configured to burn hydrogen to convert chemical energy into mechanical energy. The fuel can therefore be understood to be hydrogen. The pressure vessel is configured to store hydrogen. The pressure vessel can be configured as a high-pressure gas holder. The pressure vessel can also be configured to store fuel such as hydrogen continuously at ambient temperatures and a nominal operating pressure of at least 350 bar or at least 700 bar.

[0015] The fuel inlet path may include a fuel inlet line through which fuel from the energy converter system's environment can be introduced into the pressure vessel. The shut-off valve can be considered part of the fuel inlet path. The shut-off valve may be positioned on and / or within the fuel inlet line to allow or prevent fuel flow through it. For this purpose, the shut-off valve can be set to a closed or open position. A malfunction of the shut-off valve may occur, for example, if it is in the closed position and yet an unusually high internal fuel leakage from the pressure vessel occurs through the shut-off valve into the fuel inlet path and / or fuel inlet line.

[0016] The fuel outlet path may include a fuel outlet line through which fuel is conveyed from the pressure vessel to the energy converter. Valves and / or other functional components for controlling and / or regulating the fuel flow through the fuel outlet line may be positioned in and / or on the fuel outlet line.

[0017] The energy conversion system can have at least one pressure vessel. For example, the energy conversion system can have several pressure vessels connected to each other via a busbar. In this case, the shut-off valve and / or valve assembly can be positioned on and / or in the busbar.

[0018] Determining the fuel behavior following the identified fuel withdrawal operation means determining the fuel behavior immediately after the identified fuel withdrawal operation. That is, the fuel behavior can be determined as soon as the fuel withdrawal operation is complete. The fuel withdrawal operation can be carried out in an active operating state of the energy conversion system. An active operating state is defined as an operating state in which the energy conversion system is generating electricity and / or performing mechanical work as intended. The energy conversion system can also be in a standby operating state and / or an inactive operating state in which less or no electricity is generated, or less or no mechanical work is performed.Fuel extraction can be performed predominantly in active operating mode. Subsequent determination of fuel behavior can be performed predominantly in standby mode and / or predominantly in inactive mode.

[0019] Detecting fuel withdrawal and subsequently determining fuel behavior means determining the fuel behavior as soon as a specific fuel withdrawal operation, carried out for at least a defined period, is detected. Fuel behavior can encompass pressure, temperature, density, and / or flow behavior of the fuel in the fuel inlet path. Fuel behavior can be determined using sensors, calculations, and / or virtual models. The sensors can include at least one pressure sensor and / or at least one temperature sensor for determining the fuel pressure and / or temperature in the pressure vessel, fuel inlet path, and / or fuel outlet path.

[0020] The detected malfunction can be evaluated by a control unit and displayed and / or made available to a user of the energy converter system. For example, the malfunction can be communicated to a vehicle occupant of a vehicle in which the energy converter system is installed, specifically displayed, when the vehicle is started. Furthermore, the malfunction can be stored in the energy converter system so that it can be read by a service technician during a vehicle inspection. Additionally, the malfunction can be automatically transmitted via a network, such as the internet, to the vicinity of the energy converter system, for example, to a receiver in a workshop.

[0021] According to one embodiment of the technology described here, it is possible to detect a fuel withdrawal operation in which fuel is drawn from the pressure vessel to the energy converter for a defined period longer than a reference period, where the reference period is at least 30 seconds. It has been found that, after a certain time during the fuel withdrawal operation and / or during the active operating state, the temperature difference between the fuel in the pressure vessel and the fuel in the fuel inlet path becomes sufficiently high, and / or is sufficiently high, so that after the fuel withdrawal operation is complete, the effects on fuel behavior described above can be observed particularly reliably.Tests have shown that a sufficiently high temperature difference is achieved either after a relatively short time or only after a somewhat longer time, depending on the operating mode of the energy conversion system. Therefore, the reference time can be at least 30 seconds, at least one minute, at least five minutes, or at least ten minutes. This means that the procedure can be carried out in such a way that the fuel behavior is only determined in the proposed manner and used as a basis for detecting potential malfunctions after the fuel extraction operation has taken place for the defined minimum time, for example, at least two minutes.

[0022] The procedure described here may also include the following steps:

[0023] - Determining a fuel pressure increase in the fuel inlet path following the determined fuel withdrawal operation,

[0024] - Comparing the determined fuel pressure increase with a reference pressure increase and

[0025] - Detecting a malfunction of the shut-off valve when the measured fuel pressure increase in the fuel inlet path is greater than the reference pressure increase.

[0026] Tests have shown that the fuel pressure rise and / or its magnitude following a sufficiently long fuel withdrawal period can be characteristic of a potential malfunction of the shut-off valve. This allows for particularly simple and reliable detection of the malfunction. The fuel pressure rise can be determined using sensors and / or virtual models. For example, fuel pressure values ​​can be measured in the fuel inlet path, from which the fuel pressure rise can be calculated.

[0027] Alternatively or additionally, the procedure can include the following steps:

[0028] - Determining a fuel inlet path pressure in the fuel inlet path following the determined fuel withdrawal operation,

[0029] - Comparing the determined fuel inlet path pressure with a reference inlet path pressure and

[0030] - Detecting a malfunction of the shut-off valve when the measured fuel inlet path pressure is higher than the reference inlet path pressure.

[0031] Tests have shown that the fuel inlet path pressure and / or a corresponding pressure behavior following a sufficiently long fuel withdrawal operation can also be characteristic of a possible malfunction of the shut-off valve. This allows for particularly simple and reliable detection of the potential malfunction. Fuel inlet path pressure can be understood as the fuel pressure behavior over time. If, for example, the fuel inlet path pressure is higher than the reference inlet path pressure for a defined period and / or by a defined differential value, the malfunction can be detected, and a malfunction of the shut-off valve can be inferred. The differential value can be understood as the pressure difference between the measured inlet path pressure and the reference inlet path pressure.The fuel inlet path pressure can be determined using sensors and / or virtual models. For example, fuel pressure values ​​can be measured in the fuel inlet path, based on which the fuel inlet path pressure can be determined.

[0032] Furthermore, the procedure may include the following steps:

[0033] - Determining an inlet path fuel density in the fuel inlet path following the detected fuel withdrawal operation and

[0034] - Detecting a malfunction of the shut-off valve based on the determined inlet path fuel density. Tests have shown that the density behavior in the fuel inlet path can also be characteristic of a possible shut-off valve malfunction. A malfunction can be inferred, for example, if the inlet path fuel density increases due to a temperature rise in the pressure vessel. That is, if it is detected that the pressure in the pressure vessel and the inlet path fuel density are increasing, a malfunction of the shut-off valve can be concluded. The potential malfunction can be detected particularly easily and reliably in this way. To determine the inlet path fuel density, a density value can be determined over time. The fuel density can be determined using sensors and / or virtual models.For example, fuel temperatures and / or fuel pressures can be measured in the pressure vessel, the fuel inlet path, and / or the fuel outlet path, based on which the fuel density can be determined. One condition for detecting the malfunction could be that the fuel temperature in the fuel inlet path is higher than the fuel temperature in the pressure vessel.

[0035] According to another aspect of the technology described here, a device for detecting a malfunction of a shut-off valve in an energy converter system is proposed, wherein the energy converter system comprises an energy converter, a pressure vessel for storing fuel, a fuel inlet path for directing fuel to the pressure vessel, a fuel outlet path for directing fuel from the pressure vessel to the energy converter, and the shut-off valve for preventing backflow of fuel from the pressure vessel into the fuel inlet path. The device is configured to:

[0036] - Detecting a fuel withdrawal operation in which fuel is directed from the pressure vessel to the energy converter for a defined period of time,

[0037] - Determining fuel behavior in the fuel inlet path following the determined fuel withdrawal operation and

[0038] - Detecting the malfunction of the shut-off valve based on the determined fuel behavior.

[0039] The device thus offers the same advantages as described in detail with reference to the method. The device can include a control unit for executing the aforementioned process steps. The control unit can include a control unit, an ECU, a computer, sensors, and / or actuators, which can be configured to perform the process steps. The device can be configured to detect a fuel withdrawal operation in which fuel is drawn from the pressure vessel to the energy converter for a defined period longer than a reference period, where the reference period is at least 30 seconds.

[0040] The device can also be configured to:

[0041] - Determining a fuel pressure increase in the fuel inlet path following the determined fuel withdrawal operation,

[0042] - Comparing the determined fuel pressure increase with a reference pressure increase and

[0043] - Detecting a malfunction of the shut-off valve when the measured fuel pressure increase in the fuel inlet path is greater than the reference pressure increase.

[0044] Furthermore, the device can be configured to:

[0045] - Determining a fuel inlet path pressure in the fuel inlet path following the determined fuel withdrawal operation,

[0046] - Comparing the determined fuel inlet path pressure with a reference inlet path pressure and

[0047] - Detecting a malfunction of the shut-off valve when the measured fuel inlet path pressure is higher than the reference inlet path pressure.

[0048] Furthermore, the device can be configured to:

[0049] - Determining an inlet path fuel density in the fuel inlet path following the detected fuel withdrawal operation and

[0050] - Detecting a malfunction of the shut-off valve based on the determined inlet path fuel density.

[0051] Another aspect of the proposed technology concerns an energy converter system. The energy converter system comprises an energy converter, a pressure vessel for storing fuel, a fuel inlet path for supplying fuel to the pressure vessel, a fuel outlet path for supplying fuel from the pressure vessel to the energy converter, and a shut-off valve to prevent backflow of fuel from the pressure vessel into the fuel inlet path. The energy converter system also includes a device as described above. Thus, the energy converter system also offers the advantages described above. The energy converter system can be configured as a fuel cell system or as an internal combustion engine system. The energy converter system can include the sensors described above, in particular at least one pressure sensor and at least one temperature sensor.The at least one pressure sensor can be configured to determine the fuel pressure in the fuel inlet path, the fuel outlet path, and / or in the at least one pressure vessel. The at least one temperature sensor can be configured to determine the fuel temperature in the fuel inlet path, the fuel outlet path, and / or in the at least one pressure vessel.

[0052] The energy conversion system is preferably configured for mobile applications such as vehicles. The energy conversion system can be configured to provide electrical energy to at least one of the vehicle's drive motors and / or to mechanically propel the vehicle. The drive motor can be understood to be a machine, for example an electric motor, used to move the vehicle.

[0053] Another aspect of the proposed technology concerns a vehicle with an energy conversion system as described above, wherein the energy conversion system is configured to generate electrical current in the vehicle or to perform mechanical work to propel the vehicle. The vehicle may have at least one electric motor for propelling the vehicle, and the energy conversion system may be configured to supply power to the at least one electric motor. Thus, the vehicle offers the same advantages as described in detail with regard to the energy conversion system. The term "vehicle" can refer to a motor vehicle such as a motorized two-wheeler, a passenger car, or a truck. It can also refer to a road vehicle, an aircraft, a watercraft, a rail vehicle, a spacecraft, or a robot.The term "vehicle" can also include a purely electric vehicle and a hybrid electric vehicle, which, in addition to at least one electric motor, has an internal combustion engine for propelling the vehicle.

[0054] Furthermore, the technology disclosed herein comprises a computer program product and a computer-readable, in particular non-volatile, storage medium on which the computer program product is stored. Thus, the computer program product and the computer-readable storage medium also offer the advantages described above. The computer program product can include instructions that, when executed by a computer, for example, a computer of a vehicle control unit, cause the computer to execute the proposed method in a vehicle as described above.

[0055] The computer program product can be implemented as machine-readable instruction code in any suitable programming language and / or machine language, such as Java, C++, C#, and / or Python. The computer program product can be stored on a machine-readable storage medium such as a data disk, removable drive, volatile or non-volatile memory, and / or onboard memory / processor. The instruction code can program a computer and other programmable devices, such as a control unit, to perform the desired functions. Furthermore, the computer program product can be made available on a network, such as the internet, from which it can be downloaded by a user as needed.The computer program product can be implemented using software, one or more special electronic circuits (i.e., in hardware), or in any hybrid form (i.e., using software components and hardware components).

[0056] Further features and combinations of features of the proposed technology will become apparent from the following description of various embodiments, which are schematically illustrated in the figures. All features and / or advantages arising from the claims, the description, and the figures, including design details and spatial arrangements, can be significant both individually and in combination with one another.

[0057] They each show schematically:

[0058] Fig. 1 shows an energy converter system according to an embodiment of the present technology,

[0059] Fig. 2 shows a computer-readable storage medium with a computer program product stored thereon according to an embodiment of the present technology,

[0060] Fig. 3 shows a vehicle with an energy converter system according to an embodiment of the present technology and Fig. 4 shows a flowchart to explain a method according to an embodiment of the present technology.

[0061] Elements with the same function and mode of operation are each provided with the same reference symbols in the figures.

[0062] Fig. 1 shows an energy converter system 10 according to one possible embodiment. The energy converter system 10 is depicted as part of a fuel cell system. The energy converter system 10 comprises an energy converter 11 in the form of a fuel cell stack and a pressure vessel 12 in the form of a high-pressure fuel tank. The energy converter system further comprises a fuel inlet path 13 for directing fuel to the pressure vessel 12, a fuel outlet path 14 for directing fuel from the pressure vessel 12 to the energy converter 11, and a shut-off valve 15 for preventing backflow of fuel from the pressure vessel 12 into the fuel inlet path 13. In the illustrated embodiment, the shut-off valve 15 is configured as part of a valve arrangement 16 on the pressure vessel 12. The energy converter system 10 also has a further shut-off valve 19 at a fuel inlet 18 of the fuel inlet path 13.The shut-off valves 15, 19 are each configured as check valves.

[0063] The energy converter system 10 shown comprises a first pressure sensor 21 for determining the fuel pressure in the fuel inlet path 13 and a second pressure sensor 22 for determining the fuel pressure in the fuel outlet path 14. The energy converter system 10 also comprises a first temperature sensor 23 for determining the fuel temperature in the fuel inlet path 13 and a second temperature sensor 24 for determining the fuel temperature in the pressure vessel 12. The pressure sensors 21, 22 and the temperature sensors 23, 24 are in signal communication with a control unit 17 of the energy converter system 10. The sensors shown can be considered part of the control unit 17.

[0064] Fig. 2 shows a computer-readable and non-volatile storage medium 40 on which a computer program product 30 is stored. The storage medium 40 is in the form of a flash drive. The computer program product 30 comprises instructions which, when executed by a computer, cause the computer to execute a method for detecting a malfunction of the shut-off valve 15 in the energy converter system 10 shown. The term "computer" can be understood to refer to a part of the control unit 17 described above.

[0065] Figure 3 shows a vehicle 100 in the form of a passenger car. The vehicle 100 has an energy conversion system 10 as described above, comprising an energy converter 11 and a pressure vessel 12 for fuel. The vehicle 100 also has two electric motors 50 for propelling the vehicle 100. The energy conversion system 10 is configured to generate electrical current in the vehicle 100, which can be used to power the electric motors 50. Furthermore, the vehicle 100 has a control unit 17 configured for fault detection in the energy conversion system 10.

[0066] With reference to Fig. 4, a method for detecting a malfunction of the shut-off valve 15 is described below. In a first step S1, a defined fuel withdrawal operation is detected, during which fuel is supplied from the pressure vessel 12 to the energy converter 11 for a period of more than five minutes. Following the fuel withdrawal operation, i.e., when no more fuel is supplied from the pressure vessel 12 to the energy converter 11 and the shut-off valve 15 is in a closed state, the fuel behavior in the fuel inlet path 13 is determined in a second step S2. Here, a fuel inlet path pressure in the fuel inlet path 13 and / or a fuel pressure increase in the fuel inlet path 13 can be determined. In a third step S3, a malfunction of the shut-off valve 15 is detected based on the determined fuel behavior.For example, a malfunction of the shut-off valve 15 is concluded if the determined fuel pressure increase in the fuel inlet path 13 is greater than a reference pressure increase and / or if the determined fuel inlet path pressure is higher than a reference inlet path pressure.

[0067] The technology disclosed here allows for further design principles in addition to those illustrated. That is to say, the technology should not be considered limited to the embodiments explained with reference to the figures. For example, it is possible to determine an inlet path fuel density in the fuel inlet path 13 following the detected fuel withdrawal operation and to detect a malfunction of the shut-off valve 15 based on the determined inlet path fuel density. Furthermore, it is possible to determine and compare an inlet path fuel density in the fuel inlet path 13 following the detected fuel withdrawal operation and a pressure vessel fuel density in the pressure vessel 12, whereby a malfunction of the shut-off valve 15 is detected if the determined inlet path fuel density is higher than the determined pressure vessel fuel density.

[0068] Reference symbol list

[0069] Energy converter system Energy converter Pressure vessel

[0070] Fuel inlet path Fuel outlet path Shut-off valve

[0071] Valve assembly, control unit, fuel inlet, shut-off valve

[0072] Device first pressure sensor second pressure sensor first temperature sensor second temperature sensor computer program product storage medium electric motor

[0073] vehicle

Claims

Patent claims 1. Method for detecting a malfunction of a shut-off valve (15) of an energy converter system (10), wherein the energy converter system (10) comprises an energy converter (11), a pressure vessel (12) for storing fuel, a fuel inlet path (13) for directing fuel to the pressure vessel (12), a fuel outlet path (14) for directing fuel from the pressure vessel (12) to the energy converter (11), and the shut-off valve (15) for preventing backflow of fuel from the pressure vessel (12) into the fuel inlet path (13), comprising: - Detecting a fuel withdrawal operation in which fuel is directed from the pressure vessel (12) to the energy converter (11) for a defined time, - Determining fuel behavior in the fuel inlet path (13) following the determined fuel withdrawal operation and - Detecting the malfunction of the shut-off valve (15) based on the determined fuel behavior.

2. Method according to claim 1, comprising: - Detecting a fuel withdrawal operation in which fuel is directed from the pressure vessel (12) to the energy converter (11) for a defined time longer than a reference time, wherein the reference time is at least 30 seconds.

3. A method according to any of the preceding claims, comprising: - Determining a fuel pressure increase in the fuel inlet path (13) following the determined fuel withdrawal operation, - Comparing the determined fuel pressure increase with a reference pressure increase and - Detecting a malfunction of the shut-off valve (15) if the measured fuel pressure increase in the fuel inlet path (13) is greater than the reference pressure increase.

4. A method according to any of the preceding claims, comprising: - Determining a fuel inlet path pressure in the fuel inlet path (13) following the determined fuel withdrawal operation, - Comparing the determined fuel inlet path pressure with a reference inlet path pressure and - Detecting a malfunction of the shut-off valve (15) when the determined fuel inlet path pressure is higher than the reference inlet path pressure.

5. A method according to any of the preceding claims, comprising: - Determining an inlet path fuel density in the fuel inlet path (13) following the detected fuel withdrawal operation and - Detecting a malfunction of the shut-off valve (15) based on the determined inlet path fuel density.

6. Device (20) for detecting a malfunction of a shut-off valve (15) of an energy converter system (10), wherein the energy converter system (10) comprises an energy converter (11), a pressure vessel (12) for storing fuel, a fuel inlet path (13) for directing fuel to the pressure vessel (12), a fuel outlet path (14) for directing fuel from the pressure vessel (12) to the energy converter (11), and the shut-off valve (15) for preventing backflow of fuel from the pressure vessel (12) into the fuel inlet path (13), wherein the device (20) is configured to: - Detecting a fuel withdrawal operation in which fuel is directed from the pressure vessel (12) to the energy converter (11) for a defined time, - Determining fuel behavior in the fuel inlet path (13) following the determined fuel withdrawal operation and - Detecting the malfunction of the shut-off valve (15) based on the determined fuel behavior.

7. Device (20) according to claim 6, configured to: - Detecting a fuel withdrawal operation in which fuel is directed from the pressure vessel (12) to the energy converter (11) for a defined time longer than a reference time, wherein the reference time is at least 30 seconds.

8. Device (20) according to one of claims 6 to 7, configured to: - Determining a fuel pressure increase in the fuel inlet path (13) following the determined fuel withdrawal operation, - Comparing the determined fuel pressure increase with a reference pressure increase and - Detecting a malfunction of the shut-off valve (15) if the measured fuel pressure increase in the fuel inlet path (13) is greater than the reference pressure increase.

9. Device (20) according to any one of claims 6 to 8, configured to: - Determining a fuel inlet path pressure in the fuel inlet path (13) following the determined fuel withdrawal operation, - Comparing the determined fuel inlet path pressure with a reference inlet path pressure and - Detecting a malfunction of the shut-off valve (15) when the determined fuel inlet path pressure is higher than the reference inlet path pressure.

10. Device (20) according to any one of claims 6 to 9, configured to: - Determining an inlet path fuel density in the fuel inlet path (13) following the detected fuel withdrawal operation and - Detecting a malfunction of the shut-off valve (15) based on the determined inlet path fuel density.

11. Energy converter system (10) comprising an energy converter (11), a pressure vessel (12) for storing fuel, a fuel inlet path (13) for directing fuel to the pressure vessel (12), a fuel outlet path (14) for directing fuel from the pressure vessel (12) to the energy converter (11), a shut-off valve (15) for preventing backflow of fuel from the pressure vessel (12) into the fuel inlet path (13) and a device (20) according to any one of claims 6 to 10.

12. Vehicle (100) with an energy converter system (10) according to claim 11, wherein the energy converter system (10) is configured to generate electrical current in the vehicle (100) or to perform mechanical work to propel the vehicle (100).

13. Computer program product (30), comprising instructions which, when the computer program product (30) is executed by a computer, cause it to execute the method according to one of claims 1 to 5 in an energy converter system (10) according to claim 11 and / or in a vehicle (100) according to claim 12.

14. Computer-readable storage medium (40) with a computer program product (30) stored thereon according to claim 13.

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