Method, control device and computer program for detecting non-sealing in a fuel cell system, and sealability analysis device and fuel cell system

Abstract

The present invention relates to a method, a control device (160), a computer program, and a sealability analysis device (180) for detecting a non-sealing condition in a fuel cell system, a fuel cell system (100), and the use of a hydrogen sensor (131) disposed in the fuel cell system (100) to detect a non-sealing condition in the fuel cell system (100). The method includes receiving a hydrogen signal from a hydrogen sensor (151) disposed within the exhaust system (150); transmitting a diagnostic signal that switches the fuel cell system (100) into a diagnostic operation mode when the received hydrogen signal indicates a hydrogen concentration value that is greater than a predetermined hydrogen concentration threshold within the exhaust system (150); detecting that a membrane of a fuel cell (110) of the fuel cell system (100) is at least partially unsealed when the hydrogen signal received during the diagnostic operation of the fuel cell system (100) substantially drops; or detecting that a flush valve (137) disposed within the anode line system (130) is at least partially unsealed when the hydrogen signal received during the diagnostic operation of the fuel cell system (100) does not substantially drop; and transmitting a control signal indicative of the membrane or flush valve (137) being at least partially unsealed.

Description

[Technical Field]

[0001] The present invention relates to a method, a control device and a computer program for detecting non-sealing in a fuel cell system, in particular for locating non-sealing parts, a seal analysis device, and the use of a hydrogen sensor arranged in a fuel cell system, in particular for locating non-sealing parts.

[0002] Fuel cell systems are typically replenished with a gas mixture primarily composed of hydrogen. For this purpose, it is desirable for the replenished gas mixture to have a hydrogen concentration greater than 99%. Such a high hydrogen concentration in the gas mixture can prevent premature aging and loss of efficiency of the fuel cell. Hydrogen sensors based on thermal conductivity measurements are known from the prior art. Here, the thermal conductivity of the entire gas mixture is calculated, from which the hydrogen concentration in the gas mixture can be derived. This is because the thermal conductivity of hydrogen is significantly greater than that of many other gas components in the gas mixture.

[0003] Known from the prior art are, for example, US Pat. No. 8,795,917, Chinese Patent Application Publication No. 114,838,937, JP 2010 / 067573, US Pat. No. 10,581,100 and US Pat. No. 11,201,340.

[0004] The problem on which the invention is based is to localize any detected non-sealing in a fuel cell system.

[0005] The above problem is solved by the use of a method according to independent claim 1, a control device according to claim 6, a tightness analysis device according to claim 8, a fuel cell system according to claim 9, a computer program according to claim 10, a computer program product according to claim 11, and a hydrogen sensor arranged in the exhaust system of a fuel cell system according to claim 12. Advantageous embodiments are set out in the respective dependent claims.

[0006] The present invention is essentially based on the idea of ​​evaluating the signal of a hydrogen sensor arranged in the exhaust system of a fuel cell system to locate the non-sealing portion when a non-sealing is detected in the fuel cell system, in particular to determine whether the non-sealing is in the membrane of the fuel cell or in a flush valve arranged in the anode line of the fuel cell system. For this purpose, the non-sealing is first detected using a hydrogen sensor arranged in the exhaust system, and the fuel cell system is then switched to a diagnostic operating mode, during which no gas mixture that previously interacted with the cathode is present in the exhaust system of the fuel cell system. The non-sealing portion can be located by evaluating the hydrogen sensor signal characteristic received from the hydrogen sensor arranged in the exhaust system of the fuel cell system during the diagnostic operating mode. If the hydrogen signal curve substantially decreases during the diagnostic operating mode, a non-sealing membrane of a fuel cell of the fuel cell system can be detected. However, if the hydrogen signal curve does not substantially decrease during the diagnostic operating mode, but in particular remains substantially constant or even increases, the non-sealing portion can be assigned to the flush valve.

[0007] Thus, according to a first aspect of the present invention, a method for detecting an unsealed condition in a fuel cell system including an exhaust system is disclosed. The method includes receiving a hydrogen signal from a hydrogen sensor disposed in the exhaust system, where the hydrogen signal is indicative of a hydrogen concentration in a gas mixture present in the exhaust system. The method further includes transmitting a diagnostic signal to switch the fuel cell system into a diagnostic operation mode if the received hydrogen signal indicates a hydrogen concentration value above a predetermined hydrogen concentration threshold in the exhaust system, detecting that a membrane of a fuel cell in the fuel cell system is at least partially unsealed if the hydrogen signal received during the diagnostic operation of the fuel cell system drops substantially, or detecting that a flush valve disposed in the anode line system is at least partially unsealed if the hydrogen signal received during the diagnostic operation of the fuel cell system does not drop substantially, and transmitting a control signal indicating that the membrane or flush valve is at least partially unsealed.

[0008] Therefore, by using the method of the present invention, by evaluating the hydrogen signal of a hydrogen sensor placed in the exhaust system of a fuel cell system, non-sealings in the fuel cell system in general can be detected, and non-sealings in the fuel cell system can be located, especially after the fuel cell system has been switched into a diagnostic operating mode.

[0009] According to a preferred configuration of the method of the present invention, transmitting the diagnostic signal comprises transmitting a cathode inlet valve closing signal causing closure of a cathode inlet valve arranged in a cathode supply line of the cathode conduit system and / or transmitting a cathode outlet valve closing signal causing closure of a cathode outlet valve arranged in a cathode outlet line of the cathode conduit system, wherein the cathode supply line is configured to supply an oxygen-containing gas mixture to a cathode of the fuel cell system, and the cathode outlet line is configured to discharge the oxygen-containing gas mixture supplied to the cathode of the fuel cell system to an exhaust system.

[0010] According to the preferred embodiment, the method according to the invention allows, during a diagnostic operating mode of the fuel cell system, the presence of a gas mixture in the exhaust system of the fuel cell system that has previously interacted with the cathode of the fuel cell of the fuel cell system to be excluded, thereby enabling the location of the non-sealing part according to the invention. Here, an increase in the hydrogen concentration in the exhaust system can originate from the anode line system, in particular if the flush valve is not sealed, or from the cathode line system, in particular if the membrane of the fuel cell of the fuel cell system is not sealed. The location of the non-sealing part can be easily achieved by closing the cathode line connected to the cathode of the fuel cell of the fuel cell system.

[0011] Furthermore, in this case, it may be advantageous for transmitting the diagnostic signal to further include transmitting a bypass valve open signal causing at least partial opening of a cathode bypass valve disposed in a cathode bypass line connecting the cathode line to the cathode outlet line. In this case, detecting that a membrane of a fuel cell of the fuel cell system is at least partially unsealed may include detecting that a hydrogen signal received during a diagnostic operation of the fuel cell system indicates a hydrogen concentration value substantially equal to zero. Additionally or alternatively, detecting that a flush valve of the fuel cell system is at least partially unsealed may include detecting that a hydrogen signal received during a diagnostic operation of the fuel cell system indicates a hydrogen concentration value greater than zero.

[0012] Sending a bypass valve open signal can facilitate diagnosis and location of the non-sealing because it flushes the exhaust system with oxygen-containing gas mixtures that come from the cathode line system and do not flow past the cathode of the fuel cell, resulting in hydrogen possibly present in the exhaust system coming only from the anode system due to the potentially non-sealing flush valve.

[0013] According to another advantageous embodiment of the method of the invention, the sending of the diagnostic signal comprises sending a throttle valve closing signal which causes the closing of a throttle valve arranged in the cathode outlet line downstream of the cathode outlet valve.

[0014] In this advantageous embodiment of the method according to the invention, closing the throttle valve results in a complete disconnection of the cathode line system from the exhaust system. If hydrogen is subsequently detected in the exhaust system by the hydrogen sensor, this hydrogen must originate from the anode line system due to the unsealed flush valve.

[0015] According to a further preferred configuration of the method according to the invention, the control signal is further configured to drive an operating interface for displaying a warning to an operator of the fuel cell system, the warning informing the operator that an unsealing of the membrane or the flush valve has been detected.

[0016] According to a further aspect of the present invention, a control device is disclosed, configured to carry out the steps of the method according to any one of the preceding claims.

[0017] Preferably, the control device comprises a first control device section that performs the step of receiving a hydrogen signal from the hydrogen sensor, a second control device section that performs the step of sending a diagnostic signal, a third control device section that performs the step of detecting that the membrane or flush valve is not at least partially sealed, and a fourth control device section that performs the step of sending a control signal.

[0018] According to yet another aspect of the present invention, a sealability analyzer for a fuel cell system is disclosed, the sealability analyzer comprising: a hydrogen sensor configured to generate a hydrogen signal representative of a hydrogen concentration in a gas mixture present in an exhaust system of the fuel cell system; and a control device according to the present invention.

[0019] In accordance with yet another aspect of the present invention, a fuel cell system is disclosed that includes an anode, a cathode separated from the anode by a membrane, an anode line system having a flush valve disposed therein, an exhaust system fluidly connected to the anode line system, and a sealed analytical device according to the present invention.

[0020] According to yet another aspect of the present invention, a computer program is disclosed, the computer program comprising instructions that, when executed by a computing unit, cause the computing unit to perform the method for detecting a non-sealing condition in a fuel cell system according to the present invention.

[0021] According to yet another aspect of the invention, a computer readable medium having stored thereon a computer program according to the invention is disclosed.

[0022] According to yet another aspect of the present invention, the use of a hydrogen sensor located in the exhaust system of a fuel cell system to detect a non-sealing condition in the fuel cell system using the method of the present invention is disclosed.

[0023] Additional advantages and features of the present invention will become apparent to those skilled in the art by practice of the teachings set forth herein and by examination of the individual accompanying drawings. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a schematic diagram showing a fuel cell system for a vehicle according to the present invention; [Figure 2] 2 is a graph showing exemplary characteristics of a hydrogen signal of a hydrogen sensor disposed in the exhaust system of the fuel cell system of FIG. 1 when the membrane is not sealed or the purge valve is not sealed. [Figure 3] 2 is an exemplary flowchart illustrating a method for assessing non-sealing in the fuel cell system of FIG. 1, according to the present invention.

[0025] In the framework of the present disclosure, the term "gas mixture" denotes a mixture of various gaseous components, such as hydrogen, nitrogen, air and / or inert gases, such as argon.

[0026] In the framework of this disclosure, the term "signal" refers to raw data that is converted into a form that can be transmitted over a carrier medium selected for data transmission. The conversion can be analog or digital, in which case the data is first sampled and converted into discrete (often binary-coded) values, which are then transmitted over the medium as current impulses or voltages of different amplitudes. Furthermore, in the framework of this disclosure, signals can be transmitted and received continuously. For example, digital signals are transmitted and received at intervals of a few milliseconds.

[0027] In the framework of the present disclosure, the term "diagnostic operating mode of a fuel cell system" refers to an operating mode of a fuel cell system in which various components and elements of the fuel cell system are controlled and operated to diagnose the cathode outlet valve, as opposed to a normal operating mode which includes a flushing process that may occur in the anode pipeline system.

[0028] In the context of this disclosure, "sufficiently sealed" means that, in a closed or intact state, each element blocks its respective connection path so that the gas mixture flowing through the conduit does not substantially penetrate the element. However, it is important to note that, in the context of this disclosure, an element having a leakage of about 0.1 standard milliliters per minute (S ml / min) at an overpressure of about 600 mbar can also be referred to as "sufficiently sealed." Therefore, in the context of this disclosure, an element can be referred to as "unsealed" if the leakage exceeds the aforementioned 0.1 S ml / min at an overpressure of about 600 mbar.

[0029] 1 shows a schematic diagram of a fuel cell system 100 for a vehicle according to the invention. The fuel cell system 100 comprises a fuel cell 110, e.g. a fuel cell stack. In this case, the fuel cell 110 has an anode and a cathode separated from each other by a membrane, as is known from the prior art. For example, the fuel cell 110 may be a so-called PEM fuel cell, in which the membrane is a proton exchange membrane that allows protons formed at the anode to reach the cathode.

[0030] Fuel cell system 100 further includes a tank 120 in which a gas mixture consisting essentially of hydrogen is stored, preferably under a predetermined pressure, and may include a valve (not explicitly shown in FIG. 1 ) that can control the flow of the gas mixture into and out of tank 120.

[0031] 1 further includes an anode conduit system 130 configured to supply the gas mixture discharged from the tank 120 to the anode of the fuel cell 110 and to discharge or return the gas mixture flowing by the anode. To this end, the anode conduit system 130 is fluidly connected to the tank 120 and includes an anode supply conduit 132 that supplies the gas mixture discharged from the tank 120 to an anode conduit 134, which further supplies the gas mixture to the anode of the fuel cell 110. The anode conduit system 130 further includes an anode outlet conduit 136 fluidly connected to the anode conduit 134 that discharges the gas mixture flowing through the anode conduit 134 and can be supplied to an exhaust system 150. The anode conduit system 130 further includes an anode return conduit 138 that fluidly connects the anode outlet conduit 136 to the anode supply conduit 132, and a return pump 139 is disposed within the anode return conduit 138 and configured to return the gas mixture flowing through the anode outlet conduit 136 back to the anode supply conduit 132. Thus, a circuit is formed between the anode supply conduit 132, the anode conduit 134, the anode outlet conduit 136, and the anode return conduit 138, and in this circuit, the gas mixture can be recycled and circulated by the return pump 139.

[0032] The anode line system 130 further includes a flush valve 137 located in the anode outlet line 136 downstream of the junction with the anode return line 138 and configured to open or block the anode outlet line 136. In the normal operating mode of the fuel cell 110, the flush valve 137 is closed, allowing the return pump 139 to provide the gas mixture recycling and circulation process described above.

[0033] Further, a gas sensor 131, for example a hydrogen sensor, is provided in the anode outlet line 136 and is configured to generate a hydrogen signal representative of the hydrogen concentration at a position in the anode outlet line 136 between the anode line 134 and the flush valve 137. The gas sensor 131 may be a thermal conduction-based gas sensor. The hydrogen signal of the hydrogen sensor 131 is preferably a digital signal or data that can be processed by a data processing device that may include a processor and memory.

[0034] During the normal operation mode of the fuel cell system 100, an increasing nitrogen concentration appears in the circuit described above, and therefore the signal of the gas sensor 131 further represents the nitrogen concentration in the anode line system. In particular, during the normal operation mode of the fuel cell system 100, the gas mixture present in the anode line system 130 consists almost exclusively of hydrogen and nitrogen, which can be qualitatively expressed as the sum of the hydrogen and nitrogen concentrations in the anode line system 130 totaling 100%. Therefore, based on the signal of the gas sensor 131, both the hydrogen and nitrogen concentrations in the anode line system 130 can be calculated.

[0035] The fuel cell system 100 further includes a cathode conduit system 140 consisting of a cathode supply conduit 142, a cathode conduit 144 connected to the cathode, and a cathode discharge conduit 146. The cathode conduit system 140 also includes a cathode bypass conduit 148 that fluidly connects the cathode supply conduit 142 and the cathode discharge conduit 146, and a cathode bypass valve 149 is disposed in the cathode bypass conduit 148 for blocking or opening the cathode bypass conduit 148. The cathode discharge conduit 146 allows air supplied to the cathode via the cathode supply conduit 142 to be discharged to an exhaust system 150. A pressure sensor 141 that detects the pressure in the cathode supply conduit 142 and a cathode inlet valve 145, which may be, for example, a throttle valve, are disposed in the cathode supply conduit 142. Similarly, the cathode discharge line 146 has a cathode outlet valve 147 and a pressure sensor 143 disposed downstream of the cathode outlet valve 147 in the cathode discharge line 146 for detecting the pressure in the cathode discharge line 146. Also disposed in the cathode line system 140 are a compressor 170 for compressing air, a water separator 172, and a throttle valve 174.

[0036] The throttle valve 174 is disposed in the cathode outlet line 146 downstream of the junction of the bypass line 148 with the cathode outlet line 146 and is configured to open or block the cathode outlet line 146. By closing the throttle valve, the cathode line system 140 can be blocked such that the gas mixture flow between the compressor 170 and the throttle valve 174 is deactivated or removed.

[0037] 1 further comprises an onboard power grid branch 102 that includes an electrical load. In particular, the onboard power grid branch 102 forms at least part of an electrical system that can store and distribute the electrical energy generated by the fuel cell 110.

[0038] As already explained, both the anode conduit system 130 and the cathode conduit system 140 are connected to an exhaust system 150 in which a hydrogen sensor 151 is arranged and which is configured to generate a hydrogen signal indicative of the hydrogen concentration in the gas mixture (particularly the exhaust gas) present in the exhaust system 150. The hydrogen sensor 151 may be a gas sensor based on the thermal conductivity method.

[0039] As can be further seen in Figure 1, a controller 160 is provided that is connectable to all components of the fuel cell system 100. Although separate lines for this purpose are not shown in Figure 1, such electrical connection lines may be provided in the form of connecting lines or wires or wireless communication devices. The controller 160 may have multiple controller sections, such as a first controller section 162, a second controller section 164, a third controller section 166, and a fourth controller section 168, which are described in more detail below with reference to Figure 3.

[0040] The controller 160 may have a processor or computing unit and memory. Alternatively, the controller 160 may be a processor or computing unit connected to memory. The processor may be a central processing unit (CPU). The processor may also be another general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or another programmable logic device, a discrete gate logic circuit or discrete gate transistor logic circuit, a discrete hardware component, or the like. The general-purpose processor may be a microprocessor, or the processor may be any conventional processor, or the like.

[0041] The memory may include, but is not limited to, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), or a portable read-only memory (e.g., a CD-ROM). The memory is configured to store corresponding program instructions and corresponding data.

[0042] The hydrogen sensor 151 together with the controller 160 form a seal analysis device 180 for the fuel cell system 100 .

[0043] 2 illustrates a graph plotting exemplary characteristics 210, 220 of a hydrogen signal from a hydrogen sensor 151 located within the exhaust system 150 of the fuel cell system 100. In particular, characteristic 210 represents the hydrogen signal received by the hydrogen sensor 151 when the membrane of the fuel cell 110 is not at least partially sealed, while characteristic 220 represents the hydrogen signal from the hydrogen sensor 151 when the flush valve 137 is not at least partially sealed.

[0044] 2, a first time point t1 represents the time when an unsealing condition of the fuel cell system 100 occurs. Time point t2 represents the time when the fuel cell system 100 is switched into a diagnostic operating mode. For this purpose, in particular, the cathode inlet valve 145 and / or the cathode outlet valve 147 are closed at time point t2. Then, after time point t2, an evaluation of the hydrogen signal of the hydrogen sensor 151 according to the present invention is carried out at time point t3, which may be, for example, about 5 seconds after time point t2, in order to locate the detected unsealing condition in the fuel cell system 100.

[0045] 2, the two characteristics 210, 220 of the hydrogen signal of the hydrogen sensor 151 each exhibit a hydrogen concentration value below the hydrogen concentration threshold C_H2, e.g., 8%, so that a general non-hermeticity of the fuel cell system 10 can already be detected based on exceeding the hydrogen concentration threshold C_H2.

[0046] Furthermore, before time t1, the fuel cell system 100 is in a normal operating mode in which the flush valve 137 is closed and the return pump 139 is activated. In the normal operating mode of the fuel cell system 100, as already explained, the gas mixture, in particular the hydrogen mixture, coming from the tank 120 is circulated or continuously reused in the circuit between the anode supply line 132, the anode line 134 and the anode output line 136 to the anode return line 138 due to the closed flush valve 137. If during this normal operating mode a hydrogen concentration above a predetermined hydrogen concentration threshold C_H2, for example 8%, is calculated in the exhaust system 150 before time t1, then according to the invention, the location of any general leak detected in the fuel cell system 100 is additionally determined by carrying out a flushing process and subsequently evaluating the hydrogen signal at time t3.

[0047] At the start of the flushing process of the anode line system 130 at time t1, the flush valve 137 is simultaneously opened and the return pump 139 is deactivated, so that at this time the gas mixture, in particular the hydrogen mixture, leaving the tank 120 is guided directly to the exhaust system 150 through the anode supply line 132, the anode line 134 and the anode outlet line 136. If, during the flushing process of the anode line system 130, it is subsequently detected that the hydrogen signal is substantially rising (e.g., at time t2 in FIG. 2 ), the completion of the flushing process can be determined and it can be terminated, i.e., the flush valve 137 is closed and the return pump 139 is again activated, thereby switching the fuel cell system 100 back to normal operating mode.

[0048] An exemplary embodiment of a method for detecting and locating a non-sealing condition in the fuel cell system 100 of FIG. 1 according to the present invention will now be described with additional reference to the flowchart shown in FIG. 3.

[0049] 3 starts in step 300 and then proceeds to step 310, in which the hydrogen signal is received from the hydrogen sensor 151 by the control device 160, in particular the first control device section 162. It should be pointed out once again here that the control device 160, in particular the first control device section 162, continuously receives the hydrogen signal of the hydrogen sensor 151. Thus, during the execution of the method according to the invention, the (digital) hydrogen signal of the hydrogen sensor 151 is received continuously and continuously, for example at predetermined intervals in time of a few milliseconds.

[0050] In the following step 320, it is determined whether the received hydrogen signal indicates a hydrogen concentration above a predetermined hydrogen concentration threshold C_H2. In particular, if the predetermined hydrogen concentration threshold C_H2 is exceeded, there is an increased risk of ignition of the gas mixture present in the exhaust system 150. If in step 320 it is determined that the received hydrogen signal indicates a hydrogen concentration that does not exceed the predetermined hydrogen concentration threshold C_H2, the method returns again to step 310. The fuel cell system 100 can be diagnosed as sealed as long as the method remains in steps 310 and 320.

[0051] However, if, in step 320, it is determined that the received hydrogen signal indicates a hydrogen concentration value that exceeds the predetermined hydrogen concentration threshold C_H2, the method proceeds to step 330, where the controller 160, and in particular the second controller section 164, transmits a diagnostic signal that transitions the fuel cell system 100 into a diagnostic operating mode. The transmission of the diagnostic signal may include transmitting a cathode inlet valve close signal that causes the cathode inlet valve 145 to close. Additionally or alternatively, the transmission of the diagnostic signal may include transmitting a cathode outlet valve close signal that causes the cathode outlet valve 147 to close. Additionally or alternatively, the transmission of the diagnostic signal may include transmitting a throttle valve close signal that causes the throttle valve 174 to close.

[0052] Generally, the transmission of the diagnostic signal results in a state in which the gas mixture flowing through the cathode conduit 144 and thus interacting with the cathode does not reach the exhaust system, but allows the hydrogen-containing gas mixture from the anode conduit system to flow to the cathode. For example, closing the cathode inlet valve 145 and / or the cathode outlet valve 147 allows the gas mixture, particularly air, pumped from the compressor 170 to flow directly into the exhaust system 150 without contacting the cathode of the fuel cell 110. Closing the throttle valve 174 means that the gas mixture flowing through the exhaust system 150 no longer originates from the cathode conduit system 140. Rather, the gas mixture flowing through the exhaust system 150 now originates from the anode conduit system 130.

[0053] In the following step 340, after a predetermined period of time, for example about 5 seconds (see the period between t2 and t3 in FIG. 2), i.e., after the detected end time t2 of the flushing process of the anode line system 130, a hydrogen signal is received from the hydrogen sensor 151 and evaluated in the following step 350. That is, the time t2 also indicates the end of the hydrogen discharge.

[0054] If step 350 detects that the hydrogen signal received at time t3 has a characteristic of substantially dropping, the method proceeds to step 360, where it is diagnosed that the membrane is not sealed. Based on the diagnostic operation of fuel cell system 100, in particular, it is possible to exclude a situation in which the hydrogen present in exhaust system 150 and detected by hydrogen sensor 151 originates from cathode conduit system 140. Thus, if the hydrogen signal substantially drops at time t3, it can be assumed that the hydrogen previously present in exhaust system 150 originates from cathode conduit system 140, in particular, based on the membrane of fuel cell 110 not being sealed. Based on the diagnostic operation of the fuel cell system, for example, by closing cathode inlet valve 145 and / or cathode outlet valve 147, hydrogen flowing through the unsealed membrane can no longer enter exhaust system 150, causing the hydrogen signal to substantially drop.

[0055] However, if step 350 detects that the hydrogen signal received at time t3 has a characteristic of not substantially dropping, the method proceeds to step 370, where it is diagnosed that the flush valve 137 is not sealed. In particular, based on the diagnostic operation of the fuel cell system 100, it is possible to exclude a situation in which the hydrogen present in the exhaust system 150 and detected by the hydrogen sensor 151 originates from the cathode line system 140. Thus, if the hydrogen signal does not substantially drop at time t3, it is possible to assume that the hydrogen previously present in the exhaust system 150 originates from the anode line system 130, particularly based on the flush valve 137 not being sealed. Based on the diagnostic operation of the fuel cell system, for example, by closing the cathode inlet valve 145 and / or the cathode outlet valve 147, the hydrogen flowing through the flush valve 137 can continue to enter the exhaust system 150, thereby preventing the hydrogen signal from dropping. For example, the hydrogen signal may be substantially constant.

[0056] The detection at steps 360 or 370 is performed by the controller 160 , and in particular the third controller section 166 .

[0057] After steps 360 and 370, respectively, the method proceeds to step 380, where the controller 160, and in particular the fourth controller section 168, can send a control signal indicating that the membrane or flush valve 137 is not at least partially sealed, after which the method ends in step 390.

[0058] To accelerate the above-mentioned diagnosis, it may be advantageous to additionally at least partially open the cathode bypass valve 149 after closing the cathode inlet valve 145 and / or the cathode outlet valve 147. Thus, transmitting the diagnostic signal may additionally or alternatively include transmitting a bypass valve open signal that causes at least partial opening of the cathode bypass valve 149. This may achieve a state in which the gas mixture previously present in the exhaust system 150 can be quickly flushed from the exhaust system 150 by the new gas mixture discharged from the compressor 170.

[0059] In this case, detecting that the membrane of the fuel cell 110 of the fuel cell system 100 is at least partially unsealed (see step 350) may include detecting that a hydrogen signal received during diagnostic operation of the fuel cell system indicates a hydrogen concentration value of substantially zero.

[0060] However, if it is detected during diagnostic operation of the fuel cell system 100 that the received hydrogen signal indicates a hydrogen concentration value greater than zero, the flush valve 137 can be further diagnosed as at least partially unsealed. In this case, based on the unsealed flush valve 137, the gas mixture in the exhaust path consists of a hydrogen-containing gas mixture from the anode line system 130 and a new gas mixture from the cathode line system 140.

[0061] The method of the present invention therefore makes use of the fact that the hydrogen signal of a hydrogen sensor 151 arranged in the exhaust system of the fuel cell system can be used to further localize any general non-sealing detected in the fuel cell system 100, and in particular to correlate it with the membrane or flush valve 137. This can be easily done by evaluating the hydrogen signal of the hydrogen sensor 151 arranged in the exhaust system 150 and interrupting the gas mixture flowing through the cathode of the fuel cell 110.

Claims

1. A method for detecting a non-sealing condition in a fuel cell system (100) including an exhaust system (150), the method comprising: - receiving a hydrogen signal from a hydrogen sensor (151) located in said exhaust system (150) representative of the hydrogen concentration in the gas mixture present in said exhaust system (150); - transmitting a diagnostic signal that causes the fuel cell system (100) to switch into a diagnostic operating mode when the received hydrogen signal indicates a hydrogen concentration value in the exhaust system (150) that exceeds a predetermined hydrogen concentration threshold; - detecting that a membrane of a fuel cell (110) of the fuel cell system (100) is at least partially unsealed if a hydrogen signal received during a diagnostic operation of the fuel cell system (100) drops substantially, or that a flush valve (137) arranged in an anode line system (130) is at least partially unsealed if a hydrogen signal received during a diagnostic operation of the fuel cell system (100) does not drop substantially; - sending a control signal indicating that said membrane or said flush valve (137) is at least partially unsealed; A method comprising:

2. The transmission of the diagnostic signal comprises: sending a cathode inlet valve closing signal causing the closure of a cathode inlet valve (145) arranged in a cathode supply line (142) of a cathode line system (140), said cathode supply line (142) being configured to supply a gas mixture containing oxygen to a cathode of said fuel cell system; and / or sending a cathode outlet valve closing signal to cause closure of a cathode outlet valve (147) disposed in a cathode outlet conduit (146) of the cathode conduit system (140), the cathode outlet conduit (146) being configured to discharge the oxygen-containing gas mixture supplied to the cathode of the fuel cell system (100) to the exhaust system (150); 2. The method of claim 1, comprising:

3. The transmission of the diagnostic signal further comprises: sending a bypass valve open signal causing at least partial opening of a cathode bypass valve (149) located in a cathode bypass line (148) connecting said cathode supply line (145) to said cathode outlet line (146); where: Detecting that a membrane of a fuel cell (110) of the fuel cell system (100) is at least partially unsealed comprises detecting that a hydrogen signal received during a diagnostic operation of the fuel cell system (100) exhibits a hydrogen concentration value of substantially zero; and / or Detecting that the flush valve (137) of the fuel cell system (100) is at least partially unsealed comprises detecting that a hydrogen signal received during a diagnostic operation of the fuel cell system (100) exhibits a hydrogen concentration value greater than zero. The method of claim 2.

4. The transmission of the diagnostic signal comprises: sending a throttle valve closing signal causing the closure of a throttle valve (145) arranged in said cathode outlet line (142) downstream of said cathode outlet valve (147); 4. The method according to claim 1, wherein the

5. The method of any one of claims 1 to 4, wherein the control signal is configured to drive and control an operation interface for displaying a warning to an operator of the fuel cell system (100), the warning notifying the operator that non-tightness of the membrane or the flush valve (137) has been detected.

6. A control device (160) configured to perform the steps of the method according to any one of claims 1 to 5.

7. The control device (160) a first control device section (162) that performs the step of receiving a hydrogen signal from the hydrogen sensor (151); a second control device section (164) that performs the step of sending a diagnostic signal; a third control device section (166) that performs the step of detecting when the membrane or flush valve (137) is at least partially unsealed; a fourth control device section (168) that performs the step of sending control signals; The control device (160) of claim 6, comprising:

8. A sealability analysis device (180) for a fuel cell system (100), comprising: a hydrogen sensor (151) configured to generate a hydrogen signal representative of the hydrogen concentration in the gas mixture present in the exhaust system (150) of the fuel cell system (100); - a control device (160) according to claim 6 or 7; A sealability analysis device (180) comprising:

9. A fuel cell system (100), comprising: an anode, a cathode separated from the anode by a membrane; an anode line system (130) in which a flush valve (137) is arranged; an exhaust system (150) fluidly connected to said anode conduit system (130); - a sealability analysis device (180) according to claim 8; A fuel cell system (100) comprising:

10. A computer program comprising instructions which, when executed by a computing unit, cause the computing unit to carry out the method according to any one of claims 1 to 5. Computer program.

11. A computer-readable medium storing the computer program of claim 10.

12. 6. Use of a hydrogen sensor (151) arranged in an exhaust system (150) of a fuel cell system (100) for detecting a non-sealing condition in the fuel cell system (100) by a method according to any one of claims 1 to 5.

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