Hydrogen sensor self-diagnosis system

Abstract

To check whether the hydrogen sensor is in a state where it can correctly detect hydrogen.SOLUTION: The hydrogen sensor self-diagnosis system comprises a fuel cell system 11, a hydrogen sensor 31 for detecting hydrogen gas concentration, test air flow paths 21, 22 for circulating test air to be tested by the hydrogen sensor 31, a pump unit 32 interposed in the test air flow paths 21, 22, an exhaust flow path 51 for circulating exhaust gas from the fuel cell system 11, and a control unit 40 that controls the operation of the pump unit 32 and obtains the hydrogen gas concentration from the hydrogen sensor 31. In addition, one end of the test air flow paths 21, 22 merges with the exhaust flow path 51, and the control unit 40 drives the pump unit 32 to send exhaust gas from the exhaust flow path 51 to the hydrogen sensor 31 via the test air flow paths 21, 22 for a predetermined time after the fuel cell system 11 is started, and if the detected hydrogen concentration is less than a predetermined concentration, diagnoses that the hydrogen sensor 31 is not in a normal state.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a self-diagnosis system for a hydrogen sensor.

Background Art

[0002] Conventionally, a fuel cell vehicle equipped with a fuel cell system that generates electricity using a chemical reaction between hydrogen and oxygen (air) is known. In recent years, from the perspective of reducing environmental impact, commercial vehicles such as trucks have also been developed with fuel cell systems installed. In addition, vehicles equipped with a hydrogen engine (H2 ICE) that burns hydrogen in an internal combustion engine using hydrogen as fuel are also being considered.

[0003] Hydrogen, which is used as fuel in fuel cell systems and hydrogen engines, is a gas lighter than air and is flammable. Therefore, in the event of a hydrogen leak, it is important for a hydrogen sensor to quickly and accurately detect the leaked hydrogen.

[0004] Patent Document 1 discloses a hydrogen detection element that exhibits an output corresponding to the hydrogen concentration in the atmosphere, a storage means for storing correspondence data for associating the output of the hydrogen detection element with the hydrogen concentration, and a control means for converting the output of the hydrogen detection element into the hydrogen concentration based on the correspondence data. The control means performs zero-point correction to correct the deviation of the zero point indicating the characteristics when the hydrogen concentration is zero based on the output measured at a predetermined timing when the atmosphere of the hydrogen detection element can be regarded as the atmospheric state (step S4), and adjusts the ratio of the hydrogen concentration to the output based on a parameter related to the degree of deterioration of the hydrogen detection element, thereby accurately calibrating the hydrogen sensor system.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] When the hydrogen sensor is in a deteriorated state, hydrogen leakage cannot be correctly detected. Therefore, it is important to confirm whether the hydrogen sensor can correctly detect hydrogen before starting the fuel cell system.

[0007] The present invention has been made in view of the above problems, and an object thereof is to confirm whether the state of a hydrogen sensor mounted on a vehicle equipped with a fuel cell system or a hydrogen engine can correctly detect hydrogen.

Means for Solving the Problems

[0008] The present invention has been made to solve at least a part of the above problems and can be realized as the following aspects or application examples.

[0009] (1) The self-diagnosis system of a hydrogen sensor according to this application example includes a fuel cell system that generates electricity by a chemical reaction between hydrogen gas and oxygen, a hydrogen sensor for detecting the hydrogen gas concentration, a test air flow path for flowing the test air to be inspected by the hydrogen sensor, a pump interposed in the test air flow path, an exhaust flow path for flowing the exhaust from the fuel cell system, and a control unit that controls the operation of the pump and acquires the hydrogen gas concentration from the hydrogen sensor. The self-diagnosis system of the hydrogen sensor is characterized in that one end of the test air flow path merges with the exhaust flow path, and after the fuel cell system is started, the control unit drives the pump to send exhaust to the hydrogen sensor through the test air flow path from the exhaust flow path for a predetermined time, and when the hydrogen concentration detected by the hydrogen sensor is less than a predetermined concentration, it diagnoses that the hydrogen sensor is not in a state where it can exhibit a predetermined function.

[0010] The self-diagnosis system of the hydrogen sensor according to the above application example diagnoses whether the hydrogen sensor detects hydrogen by using the hydrogen contained in the exhaust gas discharged from the fuel cell system during a predetermined time immediately after the start-up of the fuel cell system. That is, it is possible to confirm whether the state of the hydrogen sensor is a state where it can correctly detect hydrogen.

[0011] (2) The self-diagnosis system of the hydrogen sensor according to this application example includes a hydrogen engine that uses hydrogen gas as fuel, a hydrogen sensor for detecting the hydrogen gas concentration, a test air flow path for allowing the test air to be inspected by the hydrogen sensor to flow, a pump interposed in the test air flow path, an exhaust flow path for allowing the exhaust gas from the hydrogen engine to flow, and a control unit that controls the operation of the pump and acquires the hydrogen gas concentration from the hydrogen sensor. The self-diagnosis system of the hydrogen sensor is characterized in that one end of the test air flow path merges with the exhaust flow path, and the control unit drives the pump to send the exhaust gas from the exhaust flow path to the hydrogen sensor through the test air flow path for a predetermined time after the start-up of the hydrogen engine, and diagnoses that the hydrogen sensor is not in a state where it can perform a predetermined function when the hydrogen concentration detected by the hydrogen sensor is less than a predetermined concentration.

[0012] The self-diagnosis system of the hydrogen sensor according to the above application example diagnoses whether the hydrogen sensor detects hydrogen by using the hydrogen contained in the exhaust gas discharged from the hydrogen engine during a predetermined time immediately after the start-up of the hydrogen engine. That is, it is possible to confirm whether the state of the hydrogen sensor is a state where it can correctly detect hydrogen.

[0013] (3) In the self-diagnosis system of the hydrogen sensor according to the above application example (1) or (2), the hydrogen sensor may be arranged in the middle of the test air flow path. According to the above configuration, it is not necessary to place the hydrogen sensor in the place where the monitoring of hydrogen gas leakage is required, and the degree of freedom in the design of the placement location of the hydrogen sensor is improved.

[0014] (4) The self-diagnosis system of the hydrogen sensor according to the application example of (1) or (2) above further includes a hydrogen supply system for storing and circulating hydrogen. The other end of the air flow path to be inspected is arranged near the hydrogen supply system. After the lapse of the predetermined time, the control unit may drive the pump so that the air to be inspected flows from the air flow path to be inspected to the exhaust flow path. According to the above configuration, after the end of the self-diagnosis mode, it can be automatically switched to the normal hydrogen detection mode.

[0015] (5) In the self-diagnosis system of the hydrogen sensor according to the application example of (4) above, the other end side of the air flow path to be inspected may be branched. According to the above configuration, a plurality of locations where hydrogen gas leakage is to be monitored can be set, and hydrogen gas can be detected even with one hydrogen sensor.

[0016] (6) In the self-diagnosis system of the hydrogen sensor according to the application example of (4) above, the hydrogen sensor may be arranged between the other end of the air flow path to be inspected and the hydrogen supply system. According to the above configuration, a hydrogen sensor is arranged at a location where hydrogen gas leakage is to be detected. Even when the exhaust flow path is away from the hydrogen sensor, the pump can send the exhaust to the hydrogen sensor through the air flow path to be inspected, and it is possible to diagnose whether the hydrogen sensor is functioning normally.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Best Mode for Carrying Out the Invention

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the traveling direction of the vehicle is referred to as the front-rear direction, the vehicle width direction is referred to as the left-right direction, and the vehicle height direction is referred to as the up-down direction.

[0019] FIG. 1 is a schematic diagram showing a main part of a vehicle 101 equipped with a self-diagnosis system 1 for a hydrogen sensor according to the present invention and its arrangement. While referring to FIG. 1, the main configuration of the vehicle 101 and the details of the arrangement of a hydrogen gas detection system 102 for detecting leakage of hydrogen gas and a self-diagnosis system 1 for a hydrogen sensor will be described.

[0020] The vehicle 101 is a vehicle driven by using hydrogen gas as fuel. Examples of vehicles driven by using hydrogen gas as fuel include a fuel cell vehicle or a hydrogen engine vehicle. The vehicle 101 is a large vehicle such as a truck or a bus (a truck is shown in FIG. 1). In the present embodiment, the vehicle 101 is a fuel cell vehicle.

[0021] The vehicle 101 includes a fuel cell system 11, a driving motor 12, and a driving unit 13. The fuel cell system 11 generates electric power by a chemical reaction between hydrogen and oxygen and supplies it to the driving motor 12. The driving motor 12 converts electric power into rotational power. The driving unit 13 shifts or decelerates the rotational power of the driving motor 12 and transmits the power to the driving wheels 6 via a differential (not shown) and a drive shaft. The vehicle 101 travels by the electric power generated by the fuel cell system 11.

[0022] The fuel cell system 11 includes a fuel cell stack 14, an auxiliary machine group 15, a high-voltage battery 16, and a compressor 17 (air compression unit). The fuel cell stack 14 is formed by stacking fuel cells that generate electricity through the chemical reaction of hydrogen and oxygen (air). The auxiliary machine group 15 includes pipes, auxiliary machines, a cooling circuit, a current supply circuit, etc. that supply hydrogen and air (outside air) necessary for the operation of the fuel cell stack 14. The high-voltage battery 16 stores the electric power generated by the fuel cell system 11 and supplies it to the drive motor 12. The compressor 17 compresses the air supplied to the fuel cell stack 14. The water vapor generated by the reaction of hydrogen and oxygen in the fuel cell stack 14, so-called "exhaust gas", is discharged outside the vehicle through an exhaust pipe (not shown). The exhaust gas at the start of the fuel cell stack 14 usually contains a small amount of hydrogen. The self-diagnosis system 1 of the hydrogen sensor in this embodiment diagnoses the hydrogen sensor 31 using the hydrogen contained in the exhaust gas at the start.

[0023] The vehicle 101 includes a hydrogen tank 2 and a hydrogen gas filling unit 3. The hydrogen tank 2 is a compression container that stores the hydrogen gas supplied to the fuel cell stack 14. The hydrogen gas filling unit 3 has a hydrogen gas filling port (not shown) that connects to a filling nozzle (not shown) of a hydrogen gas station, which is a hydrogen gas supply source outside the vehicle, when replenishing hydrogen gas to the hydrogen tank 2. In the following description, the hydrogen gas filling unit 3, the hydrogen tank 2, the pipe (not shown) connecting the hydrogen gas filling unit 3 and the hydrogen tank 2, the hydrogen tank 2, the fuel cell stack 14, and the pipe (not shown) connecting between the hydrogen tank 2 and the fuel cell stack 14 are collectively referred to as the hydrogen supply system. The hydrogen supply system has the function of storing and circulating hydrogen gas in the vehicle 101 and supplying it to the fuel cell stack 14.

[0024] The vehicle 101 includes a vehicle power switch 4, a driver's seat display unit 5, and a control unit 40.

[0025] The vehicle power switch 4 is, for example, a push button switch provided near the driver's seat. The vehicle power switch 4 can start or stop the drive system including the fuel cell system 11 and the drive motor 12, etc., and turn on or off the power supply of the electrical components of the vehicle 101 in accordance with the user's pressing operation. Note that an accessory on operation of turning on only the power supply of the electrical components of the vehicle 101 while stopping the drive system is included. In order to simplify the description in this embodiment, the states of the vehicle power switch 4 include at least vehicle power on, vehicle power off, and accessory on. The vehicle power switch 4 may be one that involves an operation by rotation like an ignition key.

[0026] The driver's seat display unit 5 is, for example, display means provided on the instrument panel of the driver's seat. The driver's seat display unit 5 includes a monitor screen such as a liquid crystal panel and a speaker, and displays warning information and outputs sound as necessary according to the instructions of the control unit 40.

[0027] The control unit 40 is a control unit composed of an electronic computing device, for example, an ECU (Electronic Control Unit), and can communicate with each component and various sensors of the vehicle 101 via a communication network such as CAN (Controller Area Network), direct wiring, or wireless. In this embodiment, the control unit 40 operates according to a predetermined program installed in advance, and mainly has a function of executing a self-diagnosis process (hereinafter simply referred to as a self-diagnosis process) and a hydrogen detection process of a hydrogen sensor described later.

[0028] The vehicle 101 configured as described above includes a self-diagnosis system 1 for a hydrogen sensor that performs a "self-diagnosis process" to diagnose whether the hydrogen sensor 31 of the hydrogen gas detection system 102 operates normally when the fuel cell system 11 is started. The vehicle 101 also includes a hydrogen gas detection system 102 that performs a "hydrogen detection process" to detect leakage of hydrogen gas mainly in the vicinity of the hydrogen supply system while the fuel cell system 11 is operating. In the present embodiment, the self-diagnosis system 1 for the hydrogen sensor operates using a configuration common to the hydrogen gas detection system 102. The hydrogen detection process and the self-diagnosis process are not performed simultaneously, and in the present embodiment, the self-diagnosis process is executed before the hydrogen detection process.

[0029] FIG. 2 is a piping system diagram of the self-diagnosis system 1 for the hydrogen sensor and the hydrogen gas detection system 102 according to the present invention. The configuration of the self-diagnosis system 1 for the hydrogen sensor is common to the configuration of the hydrogen gas detection system 102. With reference to FIGS. 1 and 2, the piping systems of the self-diagnosis system 1 for the hydrogen sensor and the hydrogen gas detection system 102 will be described.

[0030] As shown in FIG. 2, the piping systems of the self-diagnosis system 1 for the hydrogen sensor and the hydrogen gas detection system 102 include a first flow path 21, a second flow path 22, a third flow path 51, one hydrogen detection unit 30, and a solenoid valve 23. The hydrogen detection unit 30 has a hydrogen sensor 31 and a pump unit 32.

[0031] The first flow path 21 is a pipe having one main path and a plurality of branch paths, and is mainly used for sampling to collect gas near the tip of the branch path. The third flow path 51 is a pipe for forming an exhaust gas flow path through which the exhaust gas of the fuel cell system 11 flows, and is a so-called exhaust pipe. The second flow path 22 is a pipe connecting the third flow path 51 and the hydrogen detection unit 30. The first flow path 21, the second flow path 22, and the third flow path 51 are constituted by, for example, resin or metal pipes.

[0032] As shown in FIG. 2, the branch paths of the first flow path 21 are denoted by reference numerals 21A, 21B, 21C, 21D, 21E, 21F, 21G, and 21H. The branch paths 21A, 21B, 21C, 21D, 21E, 21F, 21G, and 21H of the first flow path 21 each have open ends 211A, 211B, 211C, 211D, 211E, 211F, 211G, and 211H at their respective ends. In the following description, the open ends 211A, 211B, 211C, 211D, 211E, 211F, 211G, and 211H may be collectively referred to as the open end 211.

[0033] The sampling points at which the open ends 211 are arranged are selected from a plurality of locations on the vehicle 101. The sampling points are mainly selected from locations near the hydrogen supply system. Specifically, as shown in FIG. 1, the open end 211A is inside the vehicle cabin, the open end 211B is near the fuel cell system 11, the open ends 211C and 211D are near the front side of the hydrogen tank 2, the open ends 211D and 211E are near the center of the hydrogen tank 2, and the open ends 211F and 211G are near the rear side of the hydrogen tank 2, respectively. Note that the first flow path 21 shown in FIG. 1 mainly shows a path arranged along the frame of the vehicle 101, but this path is an example and is not limited to these paths.

[0034] As shown in FIG. 1, the hydrogen detection unit 30 is arranged near the center of an area in the vehicle 101 where there is a possibility of hydrogen gas leakage. Specifically, it is arranged near the center of an area including the vehicle cabin, the hydrogen tank 2, and the fuel cell stack 14, which requires monitoring for hydrogen gas leakage. Thereby, the difference between the maximum length and the minimum length of the first flow path 21 can be reduced.

[0035] The pump unit 32 is interposed in the main path of the first flow path 21. Hereinafter, in order to distinguish it from the air supplied to the fuel cell stack 14, "air that may contain leaked hydrogen gas" is referred to as the inspected air. The hydrogen detection unit 30 detects the hydrogen concentration of the inspected air passing through the first flow path 21 and the second flow path 22. Hereinafter, the first flow path 21 and the second flow path 22 are collectively referred to as the inspected air flow path.

[0036] The pump unit 32 is a small so-called micropump, and can be turned on and off and its rotation direction can be switched by a control signal from the control unit 40. Here, regarding the pump unit 32, the rotation direction when sucking air from the sampling point is defined as the forward rotation, and the rotation direction when sucking air from the third flow path 51 in the reverse direction is defined as the reverse rotation. In the case of forward rotation, the fluid is moved in the direction of arrow X in FIG. 2. That is, the gas near the open end 211 is sent to the hydrogen sensor 31. In the case of reverse rotation, the fluid is moved in the direction of arrow Y in FIG. 2. That is, the exhaust gas passing through the third flow path 51 is sent to the hydrogen sensor 31.

[0037] The hydrogen sensor 31 is interposed between the first flow path 21 and the second flow path 22. The first flow path 21 and the second flow path 22 may be a single continuous pipe, and as long as the hydrogen sensor 31 is provided in the pipe so as to be able to detect hydrogen in the gas flowing through the pipe. In the present embodiment, for convenience of explanation, one side is called the first flow path 21 and the other side is called the second flow path 22 with the hydrogen sensor 31 as the boundary.

[0038] The hydrogen sensor 31 is used for detecting leakage of hydrogen gas and detects the detected amount (concentration) of hydrogen gas. For the hydrogen sensor 31, for example, a catalytic combustion type, a gas thermal conductivity type, a semiconductor type, etc. can be applied. The hydrogen sensor 31 is also used for the control of the fuel cell system 11.

[0039] The solenoid valve 23 is controlled by a control signal from the control unit 40 to be in any one of a first open state that allows passage only in the direction of arrow X in FIG. 2, a second open state that allows passage only in the direction of arrow Y, and a closed state, thereby controlling the gas flow in the second flow path 22.

[0040] The hydrogen sensor 31, the pump unit 32, the solenoid valve 23, and the fuel cell system 11 are connected to be communicable and controllable with the control unit 40 (shown by a broken line in FIG. 2).

[0041] In the above piping configuration, the hydrogen gas detection system 102 sucks in the gas in the vicinity from a plurality of sampling points through the first flow path 21 by the pump unit 32 and sends it to the hydrogen sensor 31 by executing hydrogen detection processing, and the hydrogen sensor 31 detects hydrogen contained in the gas.

[0042] Also, in the above piping configuration, the self-diagnosis system 1 of the hydrogen sensor 31 operates the pump unit 32 in reverse rotation by executing self-diagnosis processing, sucks in the exhaust gas from the fuel cell system 11 from the second flow path 22, sends it to the hydrogen sensor 31, and diagnoses whether the hydrogen sensor 31 detects hydrogen contained in the exhaust gas from the fuel cell system 11. In this case, the exhaust gas that has passed through the hydrogen sensor 31 is discharged to each sampling point via the respective branch paths 21A, 21B, 21C, 21D, 21E, 21F, 21G, 21H of the first flow path 21. Here, since the open end 211A is located in the vehicle interior, there is a problem that the exhaust gas containing hydrogen gas is released into the vehicle interior. Regarding this problem, by bending the tip of the open end 211A upward and covering the tip with a deep cap to generate an air pocket, the exhaust gas is temporarily stored in the air pocket during the self-diagnosis processing, and the exhaust gas in the air pocket is sucked in during the hydrogen gas detection processing executed after the end of the self-diagnosis processing and discharged to the outside of the vehicle via the third flow path 51.

[0043] FIG. 3 is a control block diagram of the self-diagnosis system 1 of the hydrogen sensor according to the present invention. With reference to this figure, the control configuration and functions of the self-diagnosis system 1 of the hydrogen sensor will be described below.

[0044] The self-diagnosis system 1 of the hydrogen sensor includes a control unit 40 and a system component group communicably connected to the control unit 40. The system component group includes the above-described fuel cell system 11, pump unit 32, hydrogen sensor 31, vehicle power switch 4, and driver's seat display unit 5. The control unit 40 includes an information acquisition unit 41, a fuel cell management unit 42, a self-diagnosis unit 43, and a warning control unit 44. The control unit 40 executes the self-diagnosis processing of the hydrogen sensor while communicating with the system component group.

[0045] The information acquisition unit 41 acquires information regarding the system component group.

[0046] As information regarding the system component group, the information acquisition unit 41 acquires various types of information such as the operating state, measured values, and error information of each component. Specifically, the information acquisition unit 41 acquires on information or off information indicating the operating state and error information from the fuel cell system 11. The information acquisition unit 41 acquires on information or off information indicating the operating state, rotational direction information of forward rotation or reverse rotation, and error information from the pump unit 32. The information acquisition unit 41 acquires the hydrogen detection amount and error information from the hydrogen sensor 31. The information acquisition unit 41 acquires key-on information, key-off information, or accessory-on information indicating its state and error information from the vehicle power switch 4. The information acquisition unit 41 acquires first open information, second open information, or closed information from the electromagnetic valve 23.

[0047] Based on the information acquired by the information acquisition unit 41 from the system component group, the fuel cell management unit 42 monitors the operating state, measured values, and presence or absence of errors of each system component, generates monitoring information, and stores it. Further, after the self-diagnosis process executed by the self-diagnosis unit 43, while the fuel cell system 11 is operating, the fuel cell management unit 42 executes a hydrogen detection process. In the hydrogen detection process, the fuel cell management unit 42 monitors the hydrogen detection amount acquired from the hydrogen sensor 31 while operating the pump unit 32 in forward rotation. When the measured value satisfies a predetermined warning condition or there is an error, the fuel cell management unit 42 can include warning information regarding that component in the monitoring information. For example, when the hydrogen detection amount acquired in the hydrogen detection process exceeds a predetermined amount, the fuel cell management unit 42 generates warning information regarding the abnormality of the hydrogen detection amount, includes it in the monitoring information, and stores it. The fuel cell management unit 42 also generates warning information according to the diagnosis result described later of the self-diagnosis process, includes it in the monitoring information, and stores it.

[0048] The self-diagnosis unit 43 executes a self-diagnosis process. Details of the process will be described later.

[0049] The warning control unit 44 outputs a warning based on warning information regarding an abnormality in the hydrogen detection amount and the diagnosis result of the self-diagnosis unit 43. Specifically, the warning control unit 44 outputs a warning when the hydrogen sensor 31 is diagnosed as abnormal. Further, when the hydrogen detection amount is equal to or greater than a predetermined threshold value, the warning control unit 44 generates warning information regarding hydrogen gas leakage and outputs it to the driver's seat display unit 5.

[0050] FIG. 4 is a flowchart of the self-diagnosis process of the hydrogen sensor 31 according to the present invention. Hereinafter, the self-diagnosis process executed by the control unit 40 will be described along this flowchart. This routine starts in the key-off state and with the fuel cell system 11 off.

[0051] In step S101, when the information acquisition unit 41 acquires an accessory on signal indicating that an accessory on operation has been performed on the vehicle power switch 4, the self-diagnosis unit 43 starts self-diagnosis of the hydrogen sensor 31 and proceeds to step S102.

[0052] In step S102, the information acquisition unit 41 acquires a vehicle power on signal indicating that the power of the vehicle 101 has been set to the on state (vehicle power on) from the vehicle power switch 4, and then acquires an FCS on signal indicating that the fuel cell system 11 has started, and proceeds to step S103.

[0053] In step S103, the self-diagnosis unit 43 switches the electromagnetic valve 23 from the closed state to the second open state, starts the pump unit 32 and operates it in reverse rotation, starts counting the timer built in the self-diagnosis unit 43, and proceeds to step S104. The counting period of the timer is, for example, 60 seconds.

[0054] In step S104, the self-diagnosis unit 43 acquires hydrogen detection amount information from the hydrogen sensor 31 via the information acquisition unit 41, and determines whether the hydrogen detection amount is less than a predetermined amount. If this determination is true, that is, if the hydrogen detection amount is less than the predetermined amount, the process proceeds to step S105. If this determination is false, that is, if the hydrogen detection amount is not less than the predetermined amount, the process proceeds to step S106.

[0055] In step S105, the self-diagnosis unit 43 generates a log indicating that the result of the self-diagnosis is "abnormal" and stores it in a storage unit (not shown), and then proceeds to step S107. "Abnormal" means that the hydrogen sensor 31 is not in a state where it can exhibit a predetermined function (function in terms of specifications or design). Specifically, "abnormal" includes a state where the hydrogen sensor 31 itself does not function properly, or a state where the hydrogen sensor 31 itself functions properly but cannot detect hydrogen correctly. More specifically, the state of "being unable to detect hydrogen correctly" includes a state where, despite there being no electrical abnormality in the hydrogen sensor 31, hydrogen cannot be detected correctly due to dirt or the like.

[0056] In step S106, the self-diagnosis unit 43 generates a log indicating that the result of the self-diagnosis is "normal" and stores it in a storage unit (not shown), and then proceeds to step S107. "Normal" means that the hydrogen sensor 31 is in a state where it can exhibit a predetermined function (function in terms of specifications). Specifically, "normal" includes either or both of a state where the hydrogen sensor 31 itself functions properly and a state where the hydrogen sensor 31 can detect hydrogen correctly.

[0057] In step S107, the self-diagnosis unit 43 determines whether the timer started counting in step S105 has expired. If this determination result is true, that is, if the timer has expired, the process proceeds to step S108. On the other hand, if this determination result is false, that is, if the timer has not expired, the process returns to step S104.

[0058] In step S108, the self-diagnosis unit 43 switches the solenoid valve 23 from the second open state to the first open state, ends the self-diagnosis of the hydrogen sensor 31, switches the pump unit 32 to the forward rotation operation, and proceeds to step S109.

[0059] In step S109, the self-diagnosis unit 43 outputs the diagnosis result of the hydrogen sensor 31 to the driver's seat display unit 5 via the warning control unit 44, and returns from this routine. Note that the output to the driver's seat display unit 5 may be only when the diagnosis result is "abnormal".

[0060] As described above, since the vehicle 101 merges one side of the air flow path to be measured with the exhaust flow path, the pump unit 32 can be operated in reverse rotation to send the exhaust gas containing hydrogen in the exhaust flow path to the hydrogen sensor 31. Therefore, it is possible to diagnose whether the hydrogen sensor 31 is in a normal state. Since the self-diagnosis process is performed every time the vehicle 101 is started, the diagnosis can be executed regularly and frequently. Also, it is not necessary to take out the hydrogen sensor 31 for inspection. When taking out the hydrogen sensor 31 for inspection, it takes time, but in the above-described aspect, the diagnosis can be performed in a short time of about one minute. That is, the reliability of the hydrogen gas detection system 102 can be improved. Also, since the other side of the air flow path to be measured branches off, the pump unit 32 can be operated in forward rotation to send the air to be inspected from a plurality of sampling points to the hydrogen sensor 31. Therefore, hydrogen in the air to be measured can be detected by one hydrogen detection unit 30. It becomes possible to reduce the use of hydrogen detectors, and the installation cost of hydrogen detectors can be suppressed.

[0061] This concludes the description of the hydrogen sensor self-diagnosis system 1 according to the present invention. However, the aspect of the present invention is not limited to this embodiment.

[0062] For example, in the above embodiment, the vehicle 101 was a fuel cell vehicle, but it may also be a hydrogen engine vehicle. Specifically, as shown in FIG. 5, the fuel cell system 11 may be replaced with a hydrogen engine 7, and self-diagnosis processing may be executed using the exhaust gas containing hydrogen from the hydrogen engine 7. In the case of a hydrogen engine vehicle, since the pressure (flow rate) of the exhaust gas is high, the pump unit 32 may be bypassed without operating.

[0063] For example, in the above embodiment, there was one hydrogen sensor 31, but as shown in FIG. 5, a plurality of them may be provided at each sampling point (the 1st to Nth sampling points are shown in FIG. 5). In this case, by operating the pump unit 32 in reverse rotation to send the exhaust gas to each hydrogen sensor 31(1) to 31(N), it is possible to diagnose each hydrogen sensor 31(1) to 31(N).

[0064] For example, in the above embodiment, the self-diagnosis processing is executed before the hydrogen detection processing, but it may also be executed later. Specifically, the self-diagnosis processing may be executed during the period when the vehicle 101 is powered off and the fuel cell system 11 is cooled down.

[0065] For example, in the above embodiment, the pump unit 32 was provided in the first flow path 21, but it may also be provided in the second flow path 22.

Explanation of Reference Numerals

[0066] 1: Self-diagnosis system 2: Hydrogen tank 3: Hydrogen gas filling unit 4: Vehicle power switch 5: Driver's seat display unit 7: Hydrogen engine 11: Fuel cell system 14: Fuel cell stack 21: First flow path 211: Open end 22: Second flow path 23: Electromagnetic valve 30: Hydrogen detection unit 31: Hydrogen sensor 32: Pump section 40: Control section 41: Information acquisition section 42: Fuel cell management section 43: Self-diagnosis section 44: Warning control section 51: Third flow path 101: Vehicle 102: Hydrogen gas detection system

Claims

1. A fuel cell system that generates electricity through a chemical reaction between hydrogen gas and oxygen, a hydrogen sensor for detecting the hydrogen gas concentration, a test air flow path for flowing the test air to be inspected by the hydrogen sensor, a pump installed in the test air flow path, an exhaust flow path for flowing the exhaust from the fuel cell system, a control unit that controls the operation of the pump and obtains the hydrogen gas concentration from the hydrogen sensor, A self-diagnosis system for a hydrogen sensor, comprising: One end of the test air flow path merges into the exhaust flow path, After starting the fuel cell system, the control unit drives the pump to send exhaust from the exhaust flow path to the hydrogen sensor through the test air flow path for a predetermined time, When the hydrogen concentration detected by the hydrogen sensor is less than a predetermined concentration, it is diagnosed that the hydrogen sensor is not in a state where it can perform a predetermined function. A self-diagnosis system for a hydrogen sensor.

2. A hydrogen engine that uses hydrogen gas as fuel, a hydrogen sensor for detecting the hydrogen gas concentration, a test air flow path for flowing the test air to be inspected by the hydrogen sensor, a pump installed in the test air flow path, an exhaust flow path for flowing the exhaust from the hydrogen engine, a control unit that controls the operation of the pump and obtains the hydrogen gas concentration from the hydrogen sensor, A self-diagnosis system for a hydrogen sensor, comprising: One end of the test air flow path merges into the exhaust flow path, After starting the hydrogen engine, the control unit drives the pump to send exhaust from the exhaust flow path to the hydrogen sensor through the test air flow path for a predetermined time, When the hydrogen concentration detected by the hydrogen sensor is less than a predetermined concentration, it is diagnosed that the hydrogen sensor is not in a state where it can perform a predetermined function. A self-diagnosis system for a hydrogen sensor.

3. The hydrogen sensor is provided in the middle of the test air flow path. The self-diagnosis system for a hydrogen sensor according to claim 1 or 2.

4. A hydrogen supply system for storing and circulating hydrogen, further comprising: The other end of the test air flow path is arranged near the hydrogen supply system, After the elapse of the predetermined time, the control unit drives the pump so that the test air flows from the test air flow path to the exhaust flow path. The self-diagnosis system for a hydrogen sensor according to claim 1 or 2.

5. The other end of the air flow path to be inspected is branched, characterized in that The self-diagnosis system of the hydrogen sensor according to claim 4.

6. The hydrogen sensor is arranged between the other end of the air flow path to be inspected and the hydrogen supply system, characterized in that The self-diagnosis system of the hydrogen sensor according to claim 4.

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