Fuel cell system, gas tank system and method for monitoring a gas tank system

Abstract

A method for monitoring a gas tank system comprises: withdrawing a predetermined gas mass flow from a high-pressure line system of the gas tank system, each tank being connected to the high-pressure line system via a first valve device in an open state; and performing a functional check on each of the first valve devices. In the case of a function check, all the first valve devices except the first valve device to be checked currently are closed, so that in the check state, all predetermined mass flows are only removed from the tank connected to the high-pressure line system through the first valve device to be checked currently; and a test pressure that occurs stably in the high-pressure line system in the test state is detected. In a further step of the method, at least one minimum check pressure of the detected check pressures is compared with a reference pressure, and a fault signal is generated by means of the control device if a deviation of the compared check pressure from the reference pressure is greater than a threshold value.

Description

Field of the Invention

[0001] The present invention relates to a fuel cell system, in particular a fuel cell system for a motor vehicle, a gas tank system, in particular a gas tank system for a fuel cell system, and a method for monitoring a gas tank system. Background Art

[0002] Fuel cells are increasingly being used as transducers, especially also in vehicles, to directly convert the chemical energy stored in a fuel such as hydrogen together with oxygen into electrical energy. A fuel cell has an anode, a cathode, and an electrolyte membrane arranged between the anode and the cathode. Oxidation of the fuel takes place at the anode, and reduction of oxygen takes place at the cathode.

[0003] Generally, fuel is supplied from a tank to the fuel cell via a pipeline system, and the gaseous fuel is stored in the tank under high pressure. A disconnect valve or a shut-off valve is usually provided between the tank and the high-pressure part of the pipeline system. The high-pressure part is usually also connected to a pipeline part connected to the fuel cell via a pressure regulator or a flow regulating device.

[0004] A tank system for a fuel cell system is described in US Patent US7484521B2, which has a plurality of tanks. Each tank is connected to a high-pressure pipeline system via a corresponding valve. In addition, a pressure sensor is provided in the high-pressure pipeline system, which outputs the pressure detected in the high-pressure pipeline system to a control device. Summary of the Invention

[0005] In this context, the present invention provides a method for monitoring a gas tank system having the features of claim 1, a gas tank system having the features of claim 6, and a fuel cell system having the features of claim 10.

[0006] According to a first aspect of the present invention, a method for monitoring a gas tank system includes: taking out a predetermined, for example, constant or substantially constant gas mass flow from a high-pressure pipeline system of the gas tank system, wherein each tank is connected to the high-pressure pipeline system via a first valve device in an open state; and performing a function check on each of the first valve devices in the first valve device. The function check includes closing all the first valve devices except the current first valve device to be inspected, so that in the inspection state, the entire predetermined mass flow is taken out only from the tank connected to the high-pressure pipeline system through the current first valve device to be inspected; and detecting an inspection pressure that stably appears in the high-pressure pipeline system in the inspection state. In a further step of the method, at least one minimum inspection pressure among the detected inspection pressures is compared with a reference pressure, and if the deviation between the compared inspection pressure and the reference pressure is greater than a threshold value, a fault signal is generated by means of a control device.

[0007] According to a second aspect of the present invention, a gas tank system is provided, which is particularly used for a fuel cell system. The gas tank system includes a plurality of tanks for accommodating gas, a high-pressure pipeline system, a plurality of first valve devices corresponding in number to the number of tanks, each of the first valve devices being capable of switching between an open state (in which it connects the corresponding tank to the high-pressure pipeline system) and a closed state (in which it disconnects the corresponding tank from the high-pressure pipeline system), a pressure sensor for detecting the pressure in the high-pressure pipeline system, and a control device, the control device being connected to the first valve devices and the pressure sensor in a signal-transmitting manner and being arranged to cause the gas tank system to perform the method according to the first aspect of the present invention.

[0008] According to a third aspect of the present invention, a fuel cell system can in particular be configured for use in a motor vehicle, the fuel cell system including the gas tank system according to the second aspect of the present invention and including a consumption system having a fuel cell assembly, the fuel cell assembly having a fuel supply interface connected to a second valve device.

[0009] The idea underlying the present invention is that, in order to check the functional ability of the disconnect valve device or the first valve device arranged between the corresponding tank and the high-pressure pipeline system, in particular in order to check for the presence of an inadmissible high pressure loss in the disconnect valve device, the gas mass flow supplied by a tank system composed of a plurality of tanks is successively supplied from individual tanks, and the pressure that stably appears in the high-pressure pipeline system is detected. For this purpose, a functional check is performed for each first valve device. That is to say, all the first valve devices are switched successively in such a way that an inspection state is established for each first valve device and the assigned tank, in which inspection state the entire predetermined mass flow is taken only from the tank that is connected to the high-pressure pipeline system through the first valve device to be inspected currently. Therefore, compared with the state in which all the first valve devices are open, a high mass flow flows through the corresponding valve device in the inspection state. This is associated with a high flow rate in the corresponding valve device and thus also with a higher pressure loss. Therefore, the pressure loss can be reliably determined in the inspection case. For different first valve devices, the magnitude of the stable pressure that appears may be different. At least the pressure value detected in the first valve device in which the lowest stable pressure appears in the inspection state is compared with a reference value. If the deviation between the compared inspection pressure and the reference pressure is greater than a threshold value, it is inferred that an inadmissible high pressure loss occurs at this first valve device. In this case, a fault signal is generated by means of an electronic control device, for example in the form of an output and / or an input in a data memory.

[0010] One advantage of the present invention is that the first valve device can be inspected during operation, i.e., during the extraction of a pre-determined mass flow. Since, during a functional check of the first valve device, the entire mass flow is guided through only a single valve device at once, a significant pressure loss occurs at each valve device, which facilitates the comparability of measurement results and ultimately facilitates the detection of inadmissible pressure losses.

[0011] Advantageous embodiments and refinements can be derived from the other dependent claims and the description in conjunction with the drawings.

[0012] According to some embodiments, it can be provided that the maximum inspection pressure among the detected inspection pressures is used as the reference pressure. Thus, it is not necessarily required to use a fixed reference pressure, but rather a reference value related to the corresponding mass flow, which exists as a measured value. This further facilitates the implementation of the method.

[0013] According to some embodiments, it can be provided that only the minimum inspection pressure among the detected inspection pressures is compared with the reference value. Thus, the number of comparisons performed is reduced. This advantageously reduces the required computational performance.

[0014] According to some embodiments, it can be provided that the execution of the functional check additionally includes storing the respectively detected inspection pressure together with the index identifying the first valve device to be inspected currently in a data memory, wherein the generation of the fault signal includes outputting the index of the first valve device at which the deviation of the inspection pressure from the reference pressure in the inspection state is greater than the threshold value. Thus, not only can an inadmissible high pressure loss occurring at the first valve device be detected, but also the valve device at which this pressure loss occurs can be located or identified. For this purpose, the detected inspection pressures are stored together with information about which first valve device among the first valve devices is open when the corresponding inspection pressure is detected.

[0015] According to some embodiments, it can be provided that the functional check is only executed when the pressure gradient in the high-pressure pipeline system is within a pre-determined range during the extraction of a pre-determined mass flow. In this way, it can be ensured that the functional check is only executed when there is no pressure compensation between the tanks or when the possible pressure compensation (Druckausgleich) between the tanks has ended. Thus, the detected stable inspection pressure is not affected by possible compensation processes, and the detection of inadmissible pressure losses becomes more accurate and reliable.

[0016] According to some embodiments, it can be provided that each first valve device has a filter. In this case, a high pressure loss in the corresponding valve device may be attributable, for example, to the additional use of a filter. Such a state can be discovered particularly quickly and reliably by the method of the present invention.

[0017] According to some embodiments, it may be provided that each first valve device has a switchable solenoid valve, which can be switched between an open state and a closed state, for example, by means of a control device.

[0018] According to some embodiments, it may be provided that the gas tank system has a second valve device, which can be switched between an open state and a closed state for attaching the high-pressure pipeline system to the consumption system. The second valve device may, for example, be configured as a switchable solenoid valve, in particular as a valve with adjustable flow rate. Optionally, the second valve device may be connected to the control device in a signal-transmitting manner.

[0019] The features and advantages disclosed in connection with one aspect of the present invention also apply to other aspects. In particular, the control device may initiate all method steps and perform different steps itself, such as steps of obtaining respective values based on the measured physical parameters, comparing the measured parameters with reference values, outputting signals, etc. For example, the control device may have a computing unit, such as a CPU, ASIC, FPGA, etc., and have a data memory, in particular a non-volatile data memory, such as a flash memory, SD memory, etc., which can be read by the computing unit. The data memory may store software, which can be executed by the computing unit to cause the system to perform the steps of the method. Description of the Drawings

[0020] Hereinafter, the present invention will be described with reference to the illustrations of the drawings. Shown in the drawings are:

[0021] Figure 1 A schematic diagram showing a hydraulic connection diagram of a fuel cell system according to an embodiment of the present invention;

[0022] Figure 2 A flowchart showing a method according to an embodiment of the present invention.

[0023] In the drawings, unless otherwise specified, the same reference numerals denote the same or functionally identical components. Detailed Description of the Embodiments

[0024] Figure 1 Schematically shown is a fuel cell system 200, which may be used, for example, in a vehicle. The fuel cell system 200 includes a gas tank system 100 and a consumption system 205.

[0025] As Figure 1Only schematically shown, the consumption system 205 has a fuel cell assembly 210. The fuel cell assembly 210 has at least one fuel cell, preferably a plurality of fuel cells connected in series electrically, and these fuel cells are arranged to directly convert the chemical energy stored in a gaseous fuel, such as hydrogen, together with oxygen into electrical energy. As Figure 1 Also schematically shown, the fuel cell assembly 210 has a fuel supply interface 211 through which a gaseous fuel can be supplied to the fuel cell assembly 210, especially to the anode of at least one fuel cell.

[0026] Below, the gas tank system 100 will be described in connection with the fuel cell system 200, but it is not limited to this use. As Figure 1 Schematically shown, the gas tank system 100 has a plurality of tanks 1, a high-pressure pipeline system 2, a plurality of first valve devices 3 corresponding in number to the number of tanks 1, an optional pressure regulator or flow regulator 5, a pressure sensor 4, and a control device 6. Optionally, the gas tank system 100 may also have a filling interface or supply interface 20.

[0027] In Figure 1 Only exemplarily shown, thus the gas tank system 100 having three tanks 1A, 1B, 1C. However, the present invention is not limited thereto. Generally, at least two tanks 1 are provided, and more than three tanks 1 may also be provided. Each tank 1 is configured to store a gas, especially hydrogen. For example, each tank 1 may be designed to store the gas at a pressure up to 800 bar.

[0028] The high-pressure pipeline system 2 may especially have a connecting pipeline 21, a plenum 24 connected to the connecting pipeline 21, and a plurality of attachment pipelines 23 corresponding in number to the number of tanks 1, and these attachment pipelines respectively connect the plenum 24 with the corresponding tank 1. As Figure 1 Only exemplarily shown, thus the first tank 1A can be connected to the plenum 24 via the first attachment pipeline 23A, the second tank 1B can be connected to the plenum via the second attachment pipeline 23B, and the third tank 1C can be connected to the plenum via the third attachment pipeline 23C. The connecting pipeline 21 connects the plenum 24 with the consumption system 205. Optionally, a supply pipeline 22 may also be provided, which is connected to the plenum 24 and the optional supply device 20.

[0029] The first valve device 3 may respectively have a switchable solenoid valve 3, and the solenoid valve can be switched between a closed state and an open state. Generally, each first valve device 3 can be switched between a closed state and an open state. Optionally, each first valve device 3 may also have a filter 30, as Figure 1 Schematically shown. As Figure 1As schematically shown, each valve device 3 is arranged between the tank 1 and the high-pressure pipeline system 2. For example, each first valve device 3 can be arranged in the corresponding attachment pipeline 23, as Figure 1 exemplarily shown in. In the open state, the corresponding first valve device 3 connects the corresponding tank 1 to the high-pressure pipeline system 2. In the closed state, the corresponding first valve device 3 disconnects the tank 1 from the high-pressure pipeline system 2 from each other.

[0030] An optional pressure regulator or flow regulator device 5 can likewise be switched between a closed state and an open state. For this purpose, the flow regulator device 5 can have, for example, a switchable solenoid valve, which can be switched between a closed state and an open state. Generally speaking, the pressure regulator 5 is configured to change the gas flow rate and / or pressure of the gas flowing through the pressure regulator. As Figure 1 schematically shown in, the flow regulator device 5 is arranged between the consumption system 205 and the high-pressure pipeline system 2, in particular between the consumption system 205 and the connection pipeline 21. In the open state, the second valve device 5 connects the consumption system 205 to the high-pressure pipeline system 2. In the closed state, the second valve device 5 disconnects the consumption system 205 from the high-pressure pipeline system 2 from each other.

[0031] Therefore, these tanks 1 are connected to the high-pressure pipeline system 2 in parallel with each other or attached to the high-pressure pipeline system 2. In the case where the first valve device 3 is open and the flow regulator device 5 is open, these tanks 1 jointly supply a gas mass flow to the consumption system 205.

[0032] The supply pipeline 22 is connected to the supply interface 20, and the supply interface 20 can be designed as a plug interface for a tank interface, for example. As Figure 1 shown, a check valve 8 can be provided in the supply pipeline 22, which prevents gas from flowing out of the high-pressure pipeline system 2 into the supply interface 20.

[0033] As Figure 1 shown in, the pressure sensor 4 is connected to the high-pressure pipeline system 2 and is arranged to detect the pressure in the high-pressure pipeline system 2. As Figure 1 shown in, the pressure sensor 4 can detect the pressure in the gas collection chamber 24.

[0034] The control device 6 is only schematically shown as a block in Figure 1 and is implemented as an electronic control device 6. As Figure 1 exemplarily shown in, the control device 6 can have a computing unit 61, such as a CPU, ASIC, FPGA, etc., and has a data memory 62, in particular a non-volatile data memory, such as a flash memory, SD memory, etc., which can be read by the computing unit 61. Figure 1As schematically shown, the control device 6 is connected in a signal-transmitting manner to the first valve device 3, optionally to the second valve device 5, and to the pressure sensor 4, for example by a wired connection, for example via a bus system. Alternatively, a wireless connection can also be provided, for example via WiFi or the like.

[0035] The control device 6 is configured to cause the gas tank system 100 to execute Figure 2 the method M for monitoring the gas tank system 100 as shown in. For example, software can be stored in the data memory 62, which can be executed by the computing unit 61 to cause the system 100 to execute the method M.

[0036] In step M1, a pre-determined gas mass flow is withdrawn from the high-pressure pipeline system 2 of the gas tank system 100, for example by means of the consumption system 205. Here, all the first valve devices 3 are in the open state. Optionally provided flow regulating devices 5 are also in the open state. Optionally, in step M1, the pressure sensor 4 can be used to detect the pressure change curve over time in the high-pressure pipeline system 2, and the control device 6 can determine the pressure gradient from the pressure change curve. Thus, in step M1, the mass flow is supplied jointly from all the tanks 1A - 1C.

[0037] In an optional step M10, the control device 6 can check whether the pressure gradient determined when withdrawing the pre-determined mass flow in M1 is within a pre-determined range. If this is not the case (as Figure 2 shown by the symbol "-" in step M10 in), then the method M can return to step M1. If the control device 6 determines in step M10 that the pressure gradient in the high-pressure pipeline system 2 is within the pre-determined range when withdrawing the pre-determined mass flow in M1 (as Figure 2 shown by the symbol "+" in), then the method proceeds to step M2.

[0038] In step M2, a function check is performed on each of the first valve devices in the first valve device 3. Here, first, all the first valve devices 3 other than the first valve device 3 to be currently checked are closed (step M21). Thus, an inspection state is established in which the pre-determined total mass flow is withdrawn only from the tank 1 connected to the high-pressure pipeline system 2 through the first valve device 3 to be currently checked. For example, in Figure 1 the valve devices 3A, 3B, and 3C can be inspected in sequence. If the valve device 3A is the first valve device 3 to be currently checked, then in Figure 1 the example of, the control device 6 outputs a control signal to the first valve devices 3B, 3C to switch them to the closed state. Thus, the total mass flow flows out from the tank 1A via the valve device 3A. If the valve device 3B is the first valve device 3 to be currently checked, then inFigure 1 In the example of Figure 1 , the control device 6 outputs a control signal to the first valve devices 3A, 3C to switch them to the closed state. Accordingly, the entire mass flow exits the tank 1B via the valve device 3B. If the valve device 3C is the valve device 3 to be currently inspected, then in Figure 1 In the example of Figure 1 , the control device 6 outputs a control signal to the first valve devices 3A, 3B to switch them to the closed state. Accordingly, the entire mass flow exits the tank 1C via the valve device 3C.

[0039] During the functional check, the inspection pressure that stably occurs in the high-pressure pipeline system 2 in the inspection state is also detected (step M22) by means of the pressure sensor 4. Thus, for example, when inspecting the first valve device 3A (with the valve devices 3B, 3C closed), the stable pressure in the plenum chamber 24 is detected. For example, the pressure that stably occurs after a predetermined time after establishing the inspection state or after closing the (other) first valve devices 3 other than the first valve device 3 to be inspected can be detected as the inspection pressure that stably occurs. Alternatively, the detected pressure can be continuously evaluated by the control device 6, and the detected pressure is determined as the inspection pressure after the pressure gradient in the high-pressure pipeline system 2 is within a predetermined range.

[0040] Optionally, for each first valve device 3, the correspondingly detected inspection pressure is stored together with the index that identifies the first valve device 3 to be currently inspected in the data memory 62 (step M23). For example, the index can contain information that clearly identifies the corresponding valve device in a numerical or alphanumeric manner. For example, the first valve device 3A can have the index "V1". For example, when inspecting the first valve device 3A, that is, when the first valve devices 3B, 3C are closed, the inspection pressure detected in step M22 can be stored in the data memory 62 together with the index "V1". The storage of the detected inspection pressure can also be performed without storing the index, for example, in the chronological order of its detection.

[0041] Accordingly, for each combination of the first valve devices 3, steps M21 and M22 and the optional step M23 are repeated, in which all the first valve devices 3 other than the valve device 3 to be currently inspected are closed.

[0042] Then, step M3 is performed, in which the control device 6 compares at least one minimum check pressure of the detected check pressures with a reference pressure. For example, the maximum check pressure of the detected check pressures can be used as a reference pressure. That is, the control device 6 can first evaluate the check pressures stored in the data memory 62 as follows, so that the calculation unit 61 reads the maximum check pressure and the minimum check pressure from the data memory 62. The maximum check pressure can be considered as a reference pressure. The minimum check pressure is compared with the reference pressure, wherein, for example, the difference between the reference pressure and the minimum check pressure is calculated and compared with a threshold value. Optionally, this is not done only for the minimum check pressure of the detected check pressures, but for multiple or all check pressures of the detected check pressures. However, it is also conceivable that only the minimum check pressure of the detected check pressures is compared with a reference value.

[0043] If the test pressure, which is compared with the reference value, deviates from the reference pressure by more than a threshold value, such as Figure 2 In step M3, the method M transitions to step M4, as indicated by the symbol "+". In step M4, the control device 6 generates a fault signal. Step M4 can, for example, include writing a fault record into a data memory 62 by means of the calculation unit 61. For example, the calculation unit 61 can output the index of the first valve device 3 or those first valve devices 3 for which the deviation of the test pressure from the reference pressure is greater than a threshold value in the test state, and write the index as a fault record into the data memory 62. As an alternative or in addition to writing the fault record into the data memory 62, the control device 6 can output a warning signal when generating the fault record, for example a warning signal in the form of an acoustic and / or visual warning signal.

[0044] If no deviation greater than the threshold value is determined in step M3 (this is as in Figure 2 In the example, the method can return to step M1 again, as in Figure 2 The examples are shown here only.

[0045] Although the present invention has been described above by way of example by way of embodiment, the present invention is not limited thereto but can be modified in many ways. In particular, combinations of the above embodiments are also conceivable.

Claims

1. A method (M) for monitoring a gas tank system (100), the method comprising: taking out (M1) a pre - determined gas mass flow from a high - pressure pipeline system (2) of the gas tank system (100), wherein each tank (1) is connected to the high - pressure pipeline system (2) via a first valve device (3) in an open state; performing (M2) a function check on each first valve device in the first valve device (3) according to the following process: closing (M21) all first valve devices (3) except the currently to - be - inspected first valve device (3), such that in the inspection state, all of the pre - determined mass flow is taken out only from the tank (1) connected to the high - pressure pipeline system (2) through the currently to - be - inspected first valve device (3); and detecting (M22) an inspection pressure stably present in the high - pressure pipeline system (2) in the inspection state; comparing (M3) at least one minimum inspection pressure among the detected inspection pressures with a reference pressure; and if the deviation of the compared inspection pressure from the reference pressure is greater than a threshold value, generating (M4) a fault signal by means of a control device (6).

2. The method (M) according to claim 1, wherein, the maximum inspection pressure among the detected inspection pressures is used as the reference pressure.

3. The method (M) according to claim 1 or 2, wherein, only the minimum inspection pressure among the detected inspection pressures is compared with the reference value.

4. The method (M) according to any one of the above claims, wherein, performing (M2) the function check additionally includes storing (M23) the respectively detected inspection pressures together with the index identifying the currently to - be - inspected first valve device (3) in a data memory (62), and wherein generating (M4) the fault signal includes outputting the index of the following first valve device (3), in the case of which the deviation of the inspection pressure from the reference pressure in the inspection state is greater than the threshold value.

5. The method (M) according to any one of the above claims, wherein, the function check (M2) is performed only when the pressure gradient in the high - pressure pipeline system (2) is within a pre - determined range when taking out (M1) the pre - determined mass flow.

6. A gas tank system (100), especially for a fuel cell system (200), the gas tank system having: a plurality of tanks (1) for accommodating gas; a high - pressure pipeline system (2); a plurality of first valve devices (3) corresponding in number to the number of the tanks (1), each of which can be switched between an open state and a closed state, in the open state, the first valve device connects the corresponding tank (1) to the high - pressure pipeline system (2), and in the closed state, the first valve device disconnects the corresponding tank (1) from the high - pressure pipeline system (2); a pressure sensor (4) for detecting the pressure in the high - pressure pipeline system (2); and A control device (6), which is connected to the first valve device (3) and to the pressure sensor (4) in a signal-transmitting manner and is configured to cause the gas tank system (100) to perform the method (M) according to one of the preceding claims.

7. The gas tank system (100) according to claim 6, wherein, each first valve device (3) has a filter (30).

8. The gas tank system (100) according to claim 6 or 7, wherein, each first valve device (3) has a switchable solenoid valve, which can be switched between an open state and a closed state.

9. The gas tank system (100) according to one of claims 6 to 8, the gas tank system additionally having: a flow rate regulating device (5), which can be switched between an open state and a closed state and is used to attach the high-pressure pipeline system (2) to the consumption system (205).

10. A fuel cell system (200), in particular for a motor vehicle, the fuel cell system having: the gas tank system (100) according to one of claims 6 to 9; and a consumption system (205), which has a fuel cell assembly (210), and the fuel cell assembly has a fuel supply interface (211) connected to a second valve device (5).

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