Failure determination device and failure determination method

Abstract

The invention provides a failure determination device and a failure determination method. A fuel supply system is provided with a hydrogen engine, a fuel tank, hydrogen piping, and first and second shutoff valves that serve as shutoff valves for shutting off hydrogen gas. When an operation for requesting to stop the hydrogen engine is performed, the malfunction determination device executes a malfunction determination routine in which, after the shut-off valve is closed, the decrease speed of the pressure of hydrogen gas downstream of the shut-off valve is observed in a state in which the hydrogen engine is continued to operate, and when the decrease speed is slower, it is determined that the shut-off valve is not normally closed. When an operation requiring operation of the hydrogen engine is performed during execution of the failure determination routine, the failure determination device opens the shut-off valve and stops the failure determination routine in a state in which the hydrogen engine continues to operate.

Description

Technical Field

[0001] This disclosure relates to a fault determination device and a fault determination method. Background Technology

[0002] Japanese Patent Application Publication No. 2000-274311 discloses a fault detection device in a fuel supply system. The fuel supply system includes a hydrogen engine fueled by hydrogen and a fuel tank for storing hydrogen for the hydrogen engine. The hydrogen stored in the fuel tank is supplied to the hydrogen engine via a hydrogen piping. The fuel supply system has a shut-off valve on the hydrogen piping. The shut-off valve is used to cut off the supply of hydrogen from the fuel tank to the hydrogen engine in the hydrogen piping.

[0003] The fault determination device described in the aforementioned patent document executes a fault determination routine. In this routine, the device determines whether the shut-off valve has malfunctioned based on the pressure shift of the hydrogen gas in the section between the shut-off valve and the hydrogen engine, when the shut-off valve is closed and the hydrogen engine is consuming hydrogen. The state of shut-off valve malfunction referred to here means that the shut-off valve has not closed properly, and the hydrogen gas in the hydrogen piping has not been cut off.

[0004] The aforementioned fault diagnosis device keeps the shut-off valve closed until the fault diagnosis routine is completed. Therefore, hydrogen is not supplied from the fuel tank until the fault diagnosis routine is completed. Summary of the Invention

[0005] According to one aspect of this disclosure, a fault determination device is provided for a fuel supply system. The fuel supply system includes: a hydrogen engine configured to use hydrogen as fuel; a fuel tank storing the hydrogen; a hydrogen piping for guiding the hydrogen from the fuel tank to the hydrogen engine; and a shut-off valve disposed midway through the hydrogen piping and configured to cut off the supply of hydrogen from the fuel tank to the hydrogen engine. The fault determination device includes a processing circuit configured to control the shut-off valve and the hydrogen engine to determine whether the shut-off valve is faulty. The processing circuit is configured to respond to a user of a vehicle equipped with the fuel supply system... If a user requests to stop the hydrogen engine, a fault determination routine is executed, comprising the following steps: after controlling the closure of the shut-off valve, while the hydrogen engine continues to operate, observing the rate of decrease in the hydrogen pressure downstream of the shut-off valve; and determining that the shut-off valve is not properly closed based on the rate of decrease being slower than when the shut-off valve is normally closed. The processing circuit is configured to, in response to the user requesting the hydrogen engine to operate during the execution of the fault determination routine, while the hydrogen engine continues to operate, control the closure valve to open and terminate the fault determination routine.

[0006] According to one aspect of this disclosure, a fault determination method is provided, applied to a fuel supply system, the fuel supply system comprising: a hydrogen engine configured to use hydrogen as fuel, a fuel tank storing the hydrogen, a hydrogen piping for guiding the hydrogen from the fuel tank to the hydrogen engine, and a shut-off valve disposed midway through the hydrogen piping and configured to cut off the supply of hydrogen from the fuel tank to the hydrogen engine. The fault determination method controls the shut-off valve and the hydrogen engine to determine whether the shut-off valve is faulty. The fault determination method includes the following steps: in response to a user of a vehicle equipped with the fuel supply system requesting to stop the hydrogen engine, the fault determination device begins to include... The fault determination routine includes the following steps: After controlling the shut-off valve to close, while the hydrogen engine continues to operate, observe the rate of pressure drop of the hydrogen gas downstream of the shut-off valve; and determine that the shut-off valve is not properly closed based on the rate of pressure drop being slower than when the shut-off valve is normally closed; the fault determination device determines that the user has requested the hydrogen engine to operate; and in response to the user requesting the hydrogen engine to operate during the execution of the fault determination routine, the fault determination device, while the hydrogen engine continues to operate, controls the shut-off valve to open and terminates the fault determination routine. Attached Figure Description

[0007] Figure 1 This is a schematic diagram showing the structure of a fuel supply system having a fault determination device according to one embodiment. Figure 2 This is a flowchart illustrating a series of processing flows in the first fault determination routine executed by the fault determination device. Figure 3 This is a flowchart illustrating a series of processing flows in the second fault determination routine executed by the fault determination device. Detailed Implementation

[0008] The following is for reference Figures 1-3 One embodiment of the fault determination device will be described.

[0009] <Structure of Fuel Supply System 10> The fuel supply system 10 is mounted on the vehicle. For example... Figure 1 As shown, the fuel supply system 10 includes a fuel tank 11, a hydrogen piping 12, and a hydrogen engine 15.

[0010] Fuel tank 11 stores hydrogen supplied from an external source. For example... Figure 1As shown, the fuel tank 11 is connected to the hydrogen engine 15 via a hydrogen piping 12. The hydrogen piping 12 guides hydrogen from the fuel tank 11 to the hydrogen engine 15. The hydrogen guided to the hydrogen engine 15 is supplied to the cylinders of the hydrogen engine 15 through the injectors of the hydrogen engine 15.

[0011] The hydrogen engine 15 uses hydrogen as fuel. The hydrogen engine 15 outputs driving force to the vehicle equipped with the fuel supply system 10 by burning hydrogen in the cylinder.

[0012] like Figure 1 As shown, a regulator 13, multiple shut-off valves, and multiple pressure sensors are provided in the middle of the hydrogen piping 12.

[0013] The regulator 13 adjusts the pressure of the hydrogen supplied from the fuel tank 11 to the hydrogen engine 15 to a level that is usable by the hydrogen engine 15 by depressurizing the hydrogen.

[0014] Figure 1 The diagram shows the high-pressure section HS and the low-pressure section LS of hydrogen piping 12. The high-pressure section HS is the part of hydrogen piping 12 that supplies hydrogen before it passes through regulator 13. The low-pressure section LS is the part of hydrogen piping 12 that supplies hydrogen after it passes through regulator 13.

[0015] like Figure 1 As shown, the fuel supply system 10 includes a first shut-off valve 21 and a second shut-off valve 22 as multiple shut-off valves. The shut-off valves are used to cut off the supply of hydrogen from the fuel tank 11 to the hydrogen engine 15.

[0016] like Figure 1 As shown, the first shut-off valve 21 is located in the section between the fuel tank 11 and the regulator 13 in the hydrogen piping 12. When the first shut-off valve 21 is closed, the high-pressure section HS is cut off.

[0017] like Figure 1 As shown, the second shut-off valve 22 is located in the section between the regulator 13 and the hydrogen engine 15 in the hydrogen piping 12. When the second shut-off valve 22 is closed, the low-pressure section LS is cut off.

[0018] like Figure 1 As shown, the fuel supply system 10 includes a first pressure sensor 31 and a second pressure sensor 32 as multiple pressure sensors. Figure 1 As shown, the first pressure sensor 31 is located in the high-pressure section HS, downstream of the first shut-off valve 21. Figure 1 As shown, the second pressure sensor 32 is located in the low-pressure section LS, downstream of the second shut-off valve 22.

[0019] like Figure 1As shown, the fuel supply system 10 includes a fault determination device 40. The fault determination device 40 is applied to the fuel supply system 10. The fault determination device 40 is, for example, an electronic control device that controls the injection of hydrogen by the injectors of the hydrogen engine 15.

[0020] like Figure 1 As shown, the fault determination device 40 is communicatively connected to the hydrogen engine 15. The fault determination device 40 controls the operation of the hydrogen engine 15.

[0021] like Figure 1 As shown, the fault determination device 40 is communicatively connected to the first shut-off valve 21 and the second shut-off valve 22. The fault determination device 40 controls the opening and closing of the first shut-off valve 21 and the second shut-off valve 22.

[0022] like Figure 1 As shown, the fault determination device 40 is communicatively connected to the first pressure sensor 31 and the second pressure sensor 32. The fault determination device 40 is able to obtain the values ​​measured by the first pressure sensor 31 and the second pressure sensor 32.

[0023] The fault determination device 40 executes the fault determination routine. The fault determination routine is a series of processes performed by the fault determination device 40 to determine whether the shut-off valve is faulty. A shut-off valve fault, as referred to here, means that although the fault determination device 40 issues a command to close the shut-off valve, the valve fails to close properly. For example, this fault can occur when a foreign object is trapped between the shut-off valve parts.

[0024] <Handling method in the first fault diagnosis routine DF1> Figure 2 and Figure 3 This illustrates the process flow of a series of processes performed by the fault determination device 40 when executing the fault determination routine. Figure 2 and Figure 3 The series of processes shown are performed during vehicle operation. While the vehicle is running, the fault determination device 40 starts the hydrogen engine 15 and opens the first shut-off valve 21 and the second shut-off valve 22.

[0025] In step S11, the fault determination device 40 determines whether the vehicle user has performed an operation to turn off the ignition switch (IG-disconnect). Turning off the ignition switch is an operation by which the user requests to stop the hydrogen engine 15.

[0026] If the fault determination device 40 determines in step S11 that the user has not turned off the ignition switch (step S11: No), it repeats step S11. Thus, the fault determination device 40 repeats step S11 until the user turns off the ignition switch. If the fault determination device 40 determines in step S11 that the user has turned off the ignition switch (step S11: Yes), it proceeds to step S12.

[0027] When the fault determination device 40 determines that the user has turned off the ignition switch, it starts the fault determination routine. After the ignition switch is turned off, the fault determination device 40 performs the fault determination routine while the hydrogen engine 15 continues to run.

[0028] Figure 2 The processing in steps S12 to S18 involves setting the first shut-off valve 21 as the first fault determination routine DF1 of the object. The first fault determination routine DF1 is a fault determination routine that determines whether there is a fault in the first shut-off valve 21.

[0029] In step S12, the fault determination device 40 closes the first shut-off valve 21. At this time, the fault determination device 40 keeps the second shut-off valve 22 in the open state.

[0030] In the next step S13, the fault determination device 40 obtains pressure P1. Pressure P1 is the pressure of hydrogen gas downstream of the first shut-off valve 21 immediately after the first shut-off valve 21 is closed. The fault determination device 40 obtains pressure P1 from the first pressure sensor 31.

[0031] In the next step S14, the fault determination device 40 determines whether a predetermined time t1 has elapsed since the first shut-off valve 21 was closed. The predetermined time t1 is preset.

[0032] If the fault determination device 40 determines in step S14 that the predetermined time t1 has not elapsed (step S14: no), the process will proceed to step S19.

[0033] In step S19, the fault determination device 40 determines whether the user has performed an operation to turn on the ignition switch (IG-on). Turning on the ignition switch is an operation by which the user requests the hydrogen engine 15 to operate. Therefore, in step S19, the fault determination device 40 determines whether the user requested the hydrogen engine 15 to operate during the execution of the first fault determination routine DF1.

[0034] If the fault determination device 40 determines in step S19 that the user has not turned on the ignition switch (step S19: No), it will execute step S14 again.

[0035] If, during the processing in step S14, the fault determination device 40 determines that a predetermined time t1 has elapsed (step S14: Yes), it proceeds to step S15. During the processing in step S15, the fault determination device 40 obtains pressure P2. Pressure P2 is the pressure of hydrogen gas located downstream of the first shut-off valve 21 after the predetermined time t1 has elapsed since the first shut-off valve 21 was closed. The fault determination device 40 obtains pressure P2 from the first pressure sensor 31.

[0036] In the next step S16, the fault determination device 40 determines whether the difference between pressure P1 and pressure P2 is above the threshold N1.

[0037] In the first fault diagnosis routine DF1, the hydrogen flowing in the hydrogen piping 12 downstream of the first shut-off valve 21 is gradually consumed by the hydrogen engine 15 over a predetermined time t1. When the first shut-off valve 21 is not properly closed, the rate of pressure drop of the hydrogen downstream of the first shut-off valve 21 is slower compared to when the first shut-off valve 21 is properly closed.

[0038] During the processing in steps S13 to S16, the fault determination device 40 observes the rate of pressure drop of the hydrogen gas downstream of the first shut-off valve 21. The difference between pressure P1 and pressure P2 reflects the rate of pressure drop of the hydrogen gas downstream of the first shut-off valve 21.

[0039] The threshold N1 is preset by the manufacturer of the fault determination device 40. For example, the manufacturer of the fault determination device 40 measures the difference between the pressure P1 and the pressure P2 when the first shut-off valve 21 is normally closed. Furthermore, the manufacturer of the fault determination device 40 sets the threshold N1 based on the measured value.

[0040] If, during the processing in step S16, the fault determination device 40 determines that the difference between pressure P1 and pressure P2 is greater than or equal to a threshold N1 (step S16: Yes), the processing proceeds to step S17. During the processing in step S17, the fault determination device 40 determines that the first shut-off valve 21 has not malfunctioned.

[0041] If, during the processing of step S16, the fault determination device 40 determines that the difference between pressure P1 and pressure P2 is less than the threshold N1 (step S16: No), the processing proceeds to step S18. The difference between pressure P1 and pressure P2 being less than the threshold N1 indicates that the pressure drop rate of hydrogen downstream of the first shut-off valve 21 is slower than when the first shut-off valve 21 is normally closed. During the processing of step S18, the fault determination device 40 determines that the first shut-off valve 21 has malfunctioned. Thus, by outputting the determination result during the processing of step S17 or step S18, the first fault determination routine DF1 is completed.

[0042] <Handling procedures when DF1, the first fault diagnosis routine, is aborted> If, during the processing of step S19, the fault determination device 40 determines that the user has turned on the ignition switch (step S19: Yes), it will execute the processing of step S20.

[0043] In step S20, the fault determination device 40 opens the first shut-off valve 21. When the fault determination device 40 opens the first shut-off valve 21 in step S20, all shut-off valves installed in the fuel supply system 10 are in the open state. Thus, hydrogen is supplied from the fuel tank 11 to the operating hydrogen engine 15.

[0044] like Figure 3 As shown, after performing step S20, the fault determination device 40 terminates the process. Figure 2 and Figure 3 The series of processes shown. In this case, the fault determination device 40 terminates the process if it fails to determine whether the first shut-off valve 21 is faulty. Figure 2 and Figure 3 The series of processes shown. That is, when the fault determination device 40 performs the operation of turning on the ignition switch during the execution of the first fault determination routine DF1, the first fault determination routine DF1 is terminated.

[0045] <Handling methods in the second fault determination routine DF2> like Figure 3 As shown, when the first fault determination routine DF1 is completed, the fault determination device 40 will advance the processing to step S21 and start the second fault determination routine DF2. The second fault determination routine DF2 is a fault determination routine that determines whether there is a fault in the second shut-off valve 22.

[0046] Figure 3 The processing of steps S21 to S27 shown is the second fault determination routine DF2.

[0047] When the first fault determination routine DF1 ends without being terminated, the fault determination device 40 executes the second fault determination routine DF2. In this way, the fault determination device 40 sequentially changes the shut-off valves to be targeted and executes the fault determination routines from upstream.

[0048] In step S21, the fault determination device 40 closes the second shut-off valve 22.

[0049] In the next step S22, the fault determination device 40 obtains pressure P3. Pressure P3 is the pressure of hydrogen gas downstream of the second shut-off valve 22 immediately after the second shut-off valve 22 is closed. The fault determination device 40 obtains pressure P3 from the second pressure sensor 32.

[0050] In the next step S23, the fault determination device 40 determines whether a predetermined time t2 has elapsed since the second shut-off valve 22 was closed. The predetermined time t2 is preset.

[0051] If, during the processing of step S23, the fault determination device 40 determines that the predetermined time t2 has not elapsed (step S23: No), the processing proceeds to step S29. In the processing of step S29, the fault determination device 40 determines whether the user has turned on the ignition switch. Therefore, in the processing of step S29, the fault determination device 40 determines whether, during the execution of the second fault determination routine DF2, the user has requested the hydrogen engine 15 to operate.

[0052] If the fault determination device 40 determines in step S29 that the user has not turned on the ignition switch (step S29: No), it will execute step S23 again.

[0053] If, during the processing in step S23, the fault determination device 40 determines that a predetermined time t2 has elapsed (step S23: Yes), it proceeds to step S24. During the processing in step S24, the fault determination device 40 acquires pressure P4. Pressure P4 is the pressure of hydrogen gas located downstream of the second shut-off valve 22 after the predetermined time t2 has elapsed since the second shut-off valve 22 was closed. The fault determination device 40 acquires pressure P4 from the second pressure sensor 32.

[0054] In step S25, the fault determination device 40 determines whether the difference between pressure P3 and pressure P4 is greater than or equal to the threshold N2.

[0055] In the second fault diagnosis routine DF2, the hydrogen flowing in the hydrogen piping 12 downstream of the second shut-off valve 22 is gradually consumed by the hydrogen engine 15 over a predetermined time t2. When the second shut-off valve 22 is not properly closed, the rate of pressure drop of the hydrogen downstream of the second shut-off valve 22 is slower compared to when the second shut-off valve 22 is properly closed.

[0056] The difference between pressure P3 and pressure P4 reflects the rate at which the hydrogen pressure decreases downstream of the second shut-off valve 22. During the processing in steps S22 to S25, the fault determination device 40 observes the rate at which the hydrogen pressure decreases downstream of the second shut-off valve 22.

[0057] Like threshold N1, threshold N2 is preset by the manufacturer of fault determination device 40. For example, the manufacturer of fault determination device 40 measures the difference between pressure P3 and pressure P4 when the second shut-off valve 22 is normally closed. Furthermore, the manufacturer of fault determination device 40 sets threshold N2 based on the measured value.

[0058] If, during the processing in step S25, the fault determination device 40 determines that the difference between pressure P3 and pressure P4 is greater than or equal to the threshold N2 (step S25: Yes), the processing proceeds to step S26. During the processing in step S26, the fault determination device 40 determines that the second shut-off valve 22 has not malfunctioned.

[0059] If, in step S25, the fault determination device 40 determines that the difference between pressure P3 and pressure P4 is less than the threshold N2 (step S25: No), it proceeds to step S27. The difference between pressure P3 and pressure P4 being less than the threshold N2 indicates that the pressure drop rate of hydrogen downstream of the second shut-off valve 22 is slower than when the second shut-off valve 22 is normally closed. In step S27, the fault determination device 40 determines that the second shut-off valve 22 has malfunctioned. Thus, by outputting the determination result in either step S26 or step S27, the second fault determination routine DF2 is completed.

[0060] When the first fault determination routine DF1 and the second fault determination routine DF2 are completed, all fault determination routines end. After all fault determination routines have completed, the fault determination device 40 executes step S28. In step S28, the fault determination device 40 stops the hydrogen engine 15. And, the fault determination device 40 terminates... Figure 2 and Figure 3 The series of processes shown.

[0061] <Handling procedures when aborting the second fault determination routine DF2> If the fault determination device 40 determines in step S29 that the user has turned on the ignition switch (step S29: yes), it will execute step S30.

[0062] In step S30, the fault determination device 40 opens the first shut-off valve 21 and the second shut-off valve 22. As a result, all shut-off valves in the fuel supply system 10 are in the open state. This allows hydrogen to be supplied from the fuel tank 11 to the operating hydrogen engine 15.

[0063] like Figure 3 As shown, after completing step S30, the fault determination device 40 terminates the process. Figure 2 and Figure 3 The series of processes shown. In this case, the fault determination device 40 terminates the process if it fails to determine whether the second shut-off valve 22 is faulty. Figure 2 and Figure 3 The series of processes shown. That is, when the fault determination device 40 performs the operation of turning on the ignition switch during the execution of the second fault determination routine DF2, it terminates the second fault determination routine DF2.

[0064] <The function of this implementation method> During the execution of the fault diagnosis routine, the amount of fuel that the hydrogen engine 15 can use is limited because hydrogen is not supplied from the fuel tank 11.

[0065] When an operation requiring the hydrogen engine 15 to operate occurs during the execution of the fault determination routine, the fault determination device 40 opens the shut-off valve. That is, the fault determination device 40 suspends the ongoing fault determination routine and resumes the supply of hydrogen from the fuel tank 11.

[0066] <Effects of this implementation method> (1) When the fault determination device 40 has an operation that requires the user to operate the hydrogen engine 15 before the fault determination routine is completed, it can quickly restart the fuel supply so that the vehicle can be in a state that corresponds to the user's operation.

[0067] (2) The fuel supply system 10 has multiple shut-off valves. The fault determination device 40 sequentially changes the shut-off valves to be targeted from the upstream side and executes a fault determination routine in which the shut-off valve downstream of the targeted shut-off valve is in the open state. When the user performs an operation requiring the hydrogen engine 15 to operate during the execution of the fault determination routine, the fault determination device 40 opens all shut-off valves and terminates the fault determination routine.

[0068] When any of the shut-off valves is closed, hydrogen cannot be supplied from the fuel tank 11 to the hydrogen engine 15. When the fault determination device 40 requests the operation of the hydrogen engine 15 during the execution of a fault determination routine for any shut-off valve, it opens all shut-off valves. Thus, even if the fuel supply system 10 has multiple shut-off valves, the fault determination device 40 can resume supplying hydrogen from the fuel tank 11 to the hydrogen engine 15 in response to an operation requesting the operation of the hydrogen engine 15.

[0069] (3) The fuel supply system 10 has a regulator 13 on the hydrogen piping 12 for regulating the pressure of hydrogen supplied from the fuel tank 11 to the hydrogen engine 15. The fuel supply system 10 has a first shut-off valve 21 as a shut-off valve, which is located in the portion of the hydrogen piping 12 between the fuel tank 11 and the regulator 13. The fuel supply system 10 has a second shut-off valve 22 as a shut-off valve, which is located in the portion of the hydrogen piping 12 between the regulator 13 and the hydrogen engine 15. The fault determination device 40 executes a first fault determination routine DF1, which is a fault determination routine that continues to operate the hydrogen engine 15 with the first shut-off valve 21 closed and the second shut-off valve 22 open, and targets the first shut-off valve 21. The fault determination device 40 executes a second fault determination routine DF2, which is a fault determination routine that continues to operate the hydrogen engine 15 with both the first shut-off valve 21 and the second shut-off valve 22 closed, and targets the second shut-off valve 22. When a user requests the hydrogen engine 15 to operate during the execution of the first fault determination routine DF1, the fault determination device 40, while keeping the hydrogen engine 15 running, opens the first shut-off valve 21 and terminates the first fault determination routine DF1. When a user requests the hydrogen engine 15 to operate during the execution of the second fault determination routine DF2, the fault determination device 40, while keeping the hydrogen engine 15 running, opens both the first shut-off valve 21 and the second shut-off valve 22 and terminates the second fault determination routine DF2.

[0070] The fuel supply system 10 includes two shut-off valves, a first shut-off valve 21 and a second shut-off valve 22, separated by a regulator 13. The fault determination device 40 executes fault determination routines for both the first shut-off valve 21 and the second shut-off valve 22, and opens both valves 21 and 22 when the hydrogen engine 15 is required to operate during the execution of the fault determination routine. Thus, when the fuel supply system 10 has the first shut-off valve 21 and the second shut-off valve 22, the fault determination device 40 can resume supplying hydrogen from the fuel tank 11 to the hydrogen engine 15 in response to an operation requiring the hydrogen engine 15 to operate.

[0071] (4) The above-mentioned fault determination method includes the following steps (step S11): When a user of a vehicle equipped with a fuel supply system 10 performs an operation requesting the hydrogen engine 15 to be stopped, the fault determination device 40 starts the following fault determination routine: After closing the shut-off valve, while the hydrogen engine 15 continues to run, observe the rate of decrease in hydrogen pressure downstream of the shut-off valve. If the rate of decrease is slow, it is determined that the shut-off valve is not properly closed. The above-mentioned fault determination method includes the step of the fault determination device 40 determining the operation of the hydrogen engine 15 performed by the user (steps S19 and S29). The fault determination method includes the following steps (steps S20 and S30): When a user performs an operation requesting the hydrogen engine 15 to be run during the execution of the fault determination routine, the fault determination device 40 opens the shut-off valve while the hydrogen engine 15 continues to run, and terminates the fault determination routine.

[0072] When the aforementioned fault determination method requires the hydrogen engine 15 to operate during the execution of the fault determination routine, it opens the shut-off valve. In other words, the aforementioned fault determination method suspends the currently executing fault determination routine and resumes the supply of hydrogen from the fuel tank 11.

[0073] Therefore, when the above-mentioned fault determination method is used before the fault determination routine is completed, if the user requests the hydrogen engine 15 to operate, the fuel supply can be quickly restarted, so that the vehicle can be put into a driving state that corresponds to the user's operation.

[0074] <Example of Change> This embodiment can be modified as follows. This embodiment and the following modifications can be combined and implemented to the extent that they do not contradict each other technically.

[0075] The fuel supply system 10 described above includes two shut-off valves: a first shut-off valve 21 and a second shut-off valve 22. The number of shut-off valves in the fuel supply system 10 is not limited to the above embodiment. The fuel supply system 10 may have three or more shut-off valves. Alternatively, the fuel supply system 10 may have only one shut-off valve.

[0076] • The fuel supply system 10 described above has a regulator 13. The fuel supply system 10 may also not have a regulator 13.

[0077] • The fault determination device 40 described above sequentially changes the shut-off valves that are the objects of the fault determination routine, starting from the upstream side. On the other hand, the manner in which the fault determination device 40 changes the objects of the fault determination routine is not limited to the above embodiment. For example, the fault determination device 40 can sequentially change the shut-off valves that are the objects of the fault determination routine, starting from the downstream side.

[0078] The fault determination device 40 includes a CPU (Central Processing Unit), RAM (Random Access Memory), and ROM (Read-Only Memory). The fault determination device 40 performs software processing. However, this is merely an example. For instance, the fault determination device 40 may include dedicated hardware circuitry for processing at least a portion of the software processing performed in the above embodiments. The dedicated hardware circuitry is, for example, an ASIC (Application-Specific Integrated Circuit). That is, the fault determination device 40 can be configured as any of the following (a) to (c): (a) The fault determination device 40 includes a processing unit that performs all processing according to a program, and a program storage device such as a ROM that stores the program. That is, the fault determination device 40 includes a software execution unit. (b) The fault determination device 40 includes a processing unit that performs a portion of processing according to a program, and a program storage device. Furthermore, the fault determination device 40 includes dedicated hardware circuitry for performing the remaining processing. (c) The fault determination device 40 includes dedicated hardware circuitry for performing all processing. Here, there may be multiple software execution units and / or dedicated hardware circuitry. That is, the above processing can be performed by a processing circuitry that includes at least one of the software execution unit and dedicated hardware circuitry. The processing circuit may include multiple software execution devices and dedicated hardware circuits. The program storage device, or computer-readable medium, includes all storage devices that can be accessed by a general-purpose or special-purpose computer as usable media.

Claims

1. A failure determination device that is a failure determination device of a fuel supply system, the fuel supply system includes: a hydrogen engine configured to use hydrogen gas as fuel; a fuel tank that stores the hydrogen gas; a hydrogen pipe that guides the hydrogen gas from the fuel tank to the hydrogen engine; and a stop valve that is provided midway through the hydrogen pipe and configured to cut off supply of the hydrogen gas from the fuel tank to the hydrogen engine, the failure determination device includes a processing circuit configured to control the stop valve and the hydrogen engine to determine whether the stop valve has a failure, the processing circuit is configured to, in response to an operation of requesting stop of the hydrogen engine by a user of a vehicle that includes the fuel supply system, execute a failure determination routine including: after control to close the stop valve is performed, observing a rate of decrease in pressure of the hydrogen gas on a downstream side of the stop valve in a state where the hydrogen engine is continued to operate; and based on the rate of decrease being slower than when the stop valve is normally closed, determining that the stop valve is not normally closed, the processing circuit is configured to, in response to an operation of requesting operation of the hydrogen engine by the user during execution of the failure determination routine, control to open the stop valve in a state where the hydrogen engine is continued to operate, and suspend the failure determination routine.

2. The failure determination device according to claim 1, wherein the stop valve is a first stop valve, the fuel supply system further includes a second stop valve that is provided midway through the hydrogen pipe and configured to cut off supply of the hydrogen gas from the fuel tank to the hydrogen engine, the second stop valve being provided on a downstream side of the first stop valve, the failure determination routine further includes, after determining whether the first stop valve is normally closed in a state where the second stop valve is open, the following steps: after control to close the second stop valve is performed, observing a rate of decrease in pressure of the hydrogen gas on a downstream side of the second stop valve in a state where the hydrogen engine is continued to operate; and based on the rate of decrease being slower than when the second stop valve is normally closed, determining that the second stop valve is not normally closed, the processing circuit is configured to, in response to an operation of requesting operation of the hydrogen engine by the user during execution of the failure determination routine, control to open the first stop valve and the second stop valve, and suspend the failure determination routine.

3. The failure determination device according to claim 2, wherein the fuel supply system further includes a regulator on the hydrogen pipe, the regulator being configured to regulate pressure of the hydrogen gas supplied from the fuel tank to the hydrogen engine, the first stop valve is provided in a portion of the hydrogen pipe between the fuel tank and the regulator, the second stop valve is provided in a portion of the hydrogen pipe between the regulator and the hydrogen engine, the processing circuitry is configured to, in response to an operation to request operation of the hydrogen engine being performed by the user during execution of the failure determination routine on the first stop valve, control to open the first stop valve in a state in which the hydrogen engine continues to operate, and suspend the failure determination routine on the first stop valve, the processing circuitry is configured to, in response to an operation to request operation of the hydrogen engine being performed by the user during execution of the failure determination routine on the second stop valve, control to open the first stop valve and the second stop valve in a state in which the hydrogen engine continues to operate, and suspend the failure determination routine on the second stop valve.

4. A failure determination method applied to a fuel supply system, the fuel supply system includes: a hydrogen engine configured to use hydrogen gas as fuel; a fuel tank that stores the hydrogen gas; a hydrogen pipe that guides the hydrogen gas from the fuel tank to the hydrogen engine; and a stop valve that is provided midway through the hydrogen pipe and configured to cut off supply of the hydrogen gas from the fuel tank to the hydrogen engine, the failure determination method controls the stop valve and the hydrogen engine to determine whether the stop valve has a failure, the failure determination method includes the steps of: in response to an operation to request stop of the hydrogen engine being performed by a user of a vehicle that includes the fuel supply system, a failure determination device starts a failure determination routine including the steps of, after control to close the stop valve is performed, observing a decrease rate of pressure of the hydrogen gas on a downstream side of the stop valve in a state in which the hydrogen engine continues to operate; and determining that the stop valve does not normally close based on the decrease rate being slower than when the stop valve normally closes; the failure determination device determines an operation to request operation of the hydrogen engine being performed by the user; and in response to the operation to request operation of the hydrogen engine being performed by the user during execution of the failure determination routine, the failure determination device controls to open the stop valve in a state in which the hydrogen engine continues to operate, and suspends the failure determination routine. ​

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