Fuel cell system and method for detecting an anomaly in a fuel cell system

Abstract

The present invention relates to a fuel cell system. In an anomaly detection control system, a control unit (68) of the fuel cell system receives a maximum filling pressure, which corresponds to a maximum pressure value in a filling flow path (30) during a filling process, and determines that both a first and a second pressure sensor (41, 42) are normal if the difference between a feed start pressure and the maximum filling pressure is equal to or less than a reference value. If this difference is greater than the reference value, the control unit (68) determines that there is a possibility that at least one of the first and second pressure sensors (41, 42) may be abnormal.The supply start pressure corresponds to a reading from the second pressure sensor (42) at the time when the supply of fuel gas to a fuel cell (66) is first started after the filling of a fuel tank (60) with the fuel gas has been completed.

Description

Background of the invention 1. Field of the invention

[0001] The present disclosure relates to a fuel cell system and a method for detecting an abnormality of a fuel cell system. 2. Description of the related prior art

[0002] Fuel cell systems with a hydrogen tank that stores hydrogen to be supplied to a fuel cell are typically equipped with a pressure sensor for detecting the pressure in the hydrogen tank. As is known in the art, some such fuel cell systems have two separate pressure sensors, one at a filling flow path through which hydrogen is supplied to the hydrogen tank, and the other at a supply flow path through which hydrogen to be supplied to the fuel cell is removed from the hydrogen tank.These fuel cell systems determine whether there is an abnormality in the pressure sensors by comparing the pressure detected by the pressure sensor on the filling flow path when an operation to fill the hydrogen tank with hydrogen is completed and the pressure detected by the pressure sensor on the supply flow path when the supply of hydrogen to the fuel cell is started for the first time after the filling (see, for example, JP 2018-106867 A).

[0003] In addition, DE 10 2015 117 096 A1 discloses a tank device, a vehicle and a method for evaluating an output of a pressure sensor, wherein the tank device comprises a fuel gas tank which stores a fuel gas to be supplied to a gas consumption device, a first pressure sensor which detects the gas pressure when the fuel gas tank is filled with gas, a second pressure sensor which detects the pressure of the fuel gas supplied from the fuel gas tank to the gas consumption device, and a sensor output evaluation unit.The sensor output evaluation unit determines the gas pressure difference between the gas pressure detected by the first pressure sensor when the fuel gas tank is filled with gas and the gas pressure detected by the second pressure sensor when the fuel gas is first supplied from the fuel gas tank to the gas consumption device after gas filling, makes a judgment that there is no output abnormality in one of the first and second pressure sensors if the gas pressure difference is not larger than a predetermined threshold range, and makes a judgment that there is an output abnormality in one of the first and second pressure sensors if the gas pressure difference is larger than the predetermined threshold range. Summary of the invention

[0004] The inventors found that such fuel cell systems have the following new problem. Such fuel cell systems include a receptacle provided at the end of the filling flow path, and a hydrogen refueling device is attached to the receptacle when the hydrogen tank is filled with hydrogen. In these fuel cell systems, the pressure in the filling flow path may decrease after filling the hydrogen tank, for example, due to foreign matter caught in the receptacle. In such a case, the fuel cell system may not be able to accurately determine whether there is an abnormality in the pressure sensors even by comparing the pressure detected by the pressure sensor on the filling flow path after filling the hydrogen tank with the pressure detected by the pressure sensor on the supply flow path at the start of supplying hydrogen to the fuel cell.

[0005] The above problems and the resulting object are solved by the subject matter of the independent claims. Advantageous developments of the invention are the subject matter of the dependent claims. (1) A first explanatory aspect of the present disclosure relates to a fuel cell system comprising: a fuel cell; a fuel tank storing a fuel gas to be supplied to the fuel cell; a filling flow path through which the fuel gas to be supplied to the fuel tank flows; a supply flow path connecting the fuel cell and the fuel tank; a first pressure sensor mounted on the filling flow path and detecting a pressure in the filling flow path; a second pressure sensor mounted on the supply flow path and detecting a pressure of the fuel gas at an outlet of the fuel tank; a temperature sensor detecting a temperature in the fuel tank; and a control unit configured tothat it performs anomaly detection control for the first pressure sensor and the second pressure sensor. In the anomaly detection control, the control unit is configured to: obtain a maximum filling pressure from a detection value of the first pressure sensor, wherein the maximum filling pressure corresponds to the pressure in the filling flow path at a maximum pressure time when the pressure in the filling flow path becomes maximum during filling of the fuel tank with the fuel gas; determine that both the first pressure sensor and the second pressure sensor are normal when a first difference is equal to or less than a predetermined first reference value, or when a second difference is equal to or less than a predetermined second reference value, wherein the first difference corresponds to a difference between a supply start pressure and the maximum filling pressure,wherein the supply start pressure corresponds to a detection value of the second pressure sensor at the start of supplying the fuel gas to the fuel cell, that is, when the supply of the fuel gas from the fuel tank to the fuel cell is started for the first time after the filling of the fuel tank with the fuel gas is completed, and wherein the second difference corresponds to a difference between an amount of the fuel gas in the fuel tank at the start of supplying the fuel gas to the fuel cell, which is calculated using the temperature detected by the temperature sensor at the start of supplying the fuel gas to the fuel cell and the supply start pressure, and an amount of the fuel gas in the fuel tank at the maximum pressure time, which is calculated using the temperature detected by the temperature sensor at the maximum pressure time and the maximum filling pressure; and determines that there is a possibilitythat the first pressure sensor and / or the second pressure sensor is / are abnormal when the first difference is greater than the predetermined first reference value or when the second difference is greater than the predetermined second reference value. According to the fuel cell system of this aspect, even if the pressure in the filling flow path decreases after the fuel tank is filled with the fuel gas, the maximum filling pressure is closer to the pressure in the fuel tank at the end of filling, and the difference between the supply start pressure and the maximum filling pressure is more likely to be equal to or less than the reference value. This configuration thus reduces the possibility of erroneous abnormality determination for the pressure sensors. (2) The fuel cell system of the above aspect further includes a flow rate sensor that detects a flow rate of the fuel gas flowing through the filling flow path. The control unit is configured to start the abnormality detection control when the flow rate detected by the flow rate sensor becomes equal to or lower than a predetermined reference flow rate after the start of filling the fuel tank with the fuel gas. With this configuration, the accuracy of abnormality determination for the pressure sensors is improved because the abnormality detection control is started using the detection value of the flow rate of the fuel gas flowing through the filling flow path. (3) The predetermined reference flow rate may be 30 g / sec. Thus, the accuracy of abnormality determination for the pressure sensors is improved because the abnormality detection control is started using the detection value of the flow rate of the fuel gas flowing through the filling flow path. (4) The control unit according to another illustrative aspect is configured to obtain a pressure increase rate of the filling flow path during filling the fuel tank with the fuel gas using the detection value of the first pressure sensor, and to start the abnormality detection control after the pressure increase rate after the start of filling the fuel tank with the fuel gas becomes equal to or lower than a predetermined first reference rate. With this configuration, the accuracy of anomaly determination for the pressure sensors is improved because the abnormality detection control is started using the pressure increase rate of the fuel gas flowing through the filling flow path. (5) The predetermined first reference rate may be 23 MPa / min. Thus, the accuracy of anomaly determination for the pressure sensors is improved because the anomaly detection control is started using the pressure increase rate of the fuel gas flowing through the filling flow path. (6) The control unit according to another illustrative aspect is configured to obtain a temperature increase rate of the fuel tank during filling the fuel tank with the fuel gas using the temperature detected by the temperature sensor, and to start the abnormality detection control after the temperature increase rate after the start of filling the fuel tank with the fuel gas becomes equal to or lower than a predetermined second reference rate. With this configuration, the accuracy of anomaly determination for the pressure sensors is improved because the abnormality detection control is started using the temperature increase rate of the fuel tank. (7) The predetermined second reference rate may be 20 °C / min. Thus, the accuracy of anomaly determination for the pressure sensors is improved because the anomaly detection control is started using the temperature increase rate of the fuel tank. (8) The control unit may be configured to obtain the maximum filling pressure at the maximum pressure time, wherein the maximum pressure time corresponds to a time when the detection value of the first pressure sensor becomes maximum after a pressure loss occurring between the first pressure sensor and the fuel tank when the fuel gas flows through the filling flow path is estimated to be equal to or lower than a predetermined determination value. This configuration reduces the possibility that an excessively large value may be obtained as the maximum filling pressure due to the pressure loss in the filling flow path, and thus reduces the possibility that the pressure sensors are erroneously determined to be abnormal even though the pressure sensors are normal. The accuracy of an abnormality determination for the pressure sensors is thus improved. (9) Another explanatory aspect of the present disclosure relates to a method for detecting an abnormality of a fuel cell system. The fuel cell system includes a fuel cell, a fuel tank that stores fuel gas to be supplied to the fuel cell, a filling flow path through which the fuel gas to be supplied to the fuel tank flows, a supply flow path connecting the fuel cell and the fuel tank, a first pressure sensor mounted on the filling flow path and detecting a pressure in the filling flow path, and a second pressure sensor mounted on the supply flow path and detecting a pressure of the fuel gas at an outlet of the fuel tank. The method includes: obtaining a maximum filling pressure from a detection value of the first pressure sensor, the maximum filling pressure corresponding to the pressure in the filling flow path at a maximum pressure time,when the pressure in the filling flow path becomes maximum during filling of the fuel tank with the fuel gas; determining that both the first pressure sensor and the second pressure sensor are normal when a first difference is equal to or less than a predetermined first reference value, or when a second difference is equal to or less than a predetermined second reference value, wherein the first difference corresponds to a difference between a supply start pressure and the maximum filling pressure, wherein the supply start pressure corresponds to a detection value of the second pressure sensor at the start of supplying the fuel gas to the fuel cell, that is, when supplying the fuel gas from the fuel tank to the fuel cell is started for the first time after filling the fuel tank with the fuel gas is completed,and wherein the second difference corresponds to a difference between an amount of fuel gas in the fuel tank at the start of supplying the fuel gas to the fuel cell, which is calculated using a temperature in the fuel tank at the start of supplying the fuel gas to the fuel cell and the supply start pressure, and an amount of fuel gas in the fuel tank at the maximum pressure time, which is calculated using a temperature in the fuel tank at the maximum pressure time and the maximum filling pressure; and determining that there is a possibility that the first pressure sensor and / or the second pressure sensor is / are abnormal if the first difference is greater than the predetermined first reference value or if the second difference is greater than the predetermined second reference value.

[0006] The present disclosure may be implemented in various forms other than the fuel cell system and the method for detecting an abnormality of a fuel cell system. For example, the present disclosure may be implemented in forms such as fuel cell vehicles equipped with the fuel cell system, computer programs implementing the method, and non-transitory storage media with the computer program stored therein. Short description of the figures

[0007] Features, advantages and technical and industrial significance of exemplary embodiments of the invention are described below with reference to the accompanying drawings, in which like reference numerals designate like elements, and wherein: Fig. 1 shows the general configuration of a fuel cell system; Fig. 2 is a flowchart of an anomaly detection control routine; Fig. 3 is a timing diagram illustrating an overview of operations related to anomaly detection control; Fig. 4 is a graph showing the relationship between filling time and pressure loss and filling flow rate; Fig. 5 is a flowchart of an anomaly detection control routine; Fig. 6 is a timing chart illustrating an overview of operations related to anomaly detection control; Fig. Figure 7 is a graph showing the relationship between filling time and pressure loss and pressure increase rate; Fig. 8 is a flowchart of an anomaly detection control routine; Fig. 9 is a timing chart illustrating an overview of operations related to anomaly detection control; Fig. 10 is a graph showing the relationship between filling time and pressure loss and temperature increase rate; Fig. 11 is a flowchart of an anomaly detection control routine; and Fig. 12 is a timing diagram illustrating an overview of operations related to anomaly detection control. Detailed Description of Embodiments A. First Embodiment (A-1) Overall Configuration

[0008] Fig. Figure 1 illustrates the general configuration of a fuel cell system 25 of a first embodiment of the present disclosure. The fuel cell system 25 is mounted on a fuel cell vehicle 20. Fig. 1 also illustrates a hydrogen refueling device 70 for filling a fuel tank 60 with hydrogen, which is a fuel gas. The fuel tank 60 is included in the fuel cell system 25 and will be described later. The configurations of the fuel cell vehicle 20 and the hydrogen refueling device 70 will be described.

[0009] The fuel cell system 25 corresponds to a system for generating electricity for use by a drive motor, not shown, mounted on the fuel cell vehicle 20. The fuel cell system 25 includes a fuel cell 66, the fuel tank 60, a receptacle 64, a filling line 30, a supply line 32, and a control unit 68. The fuel tank 60 and the receptacle 64 are connected by the filling line 30, and the fuel tank 60 and the fuel cell 66 are connected by the supply line 32. Fig. 1 illustrates only a part of the configuration of the fuel cell vehicle 20 with respect to the flow of hydrogen. Although the fuel cell vehicle 20 further includes a structure that causes oxygen-containing oxidizing gas to flow through the fuel cell 66, a structure that causes a cooling medium to flow through the fuel cell 66, and a structure related to driving the drive motor, description of these structures will be omitted.

[0010] The fuel cell 66 is an electric generator for generating electricity from an electrochemical reaction between fuel gas and oxidizing gas, and has a stacked structure of a plurality of individual cells. Although the fuel cell 66 of the present embodiment is a polymer electrolyte fuel cell, the fuel cell 66 may be another type of fuel cell, such as a solid oxide fuel cell. In each individual cell constituting the fuel cell 66, a flow path through which hydrogen, i.e., fuel gas, flows is formed on the anode side (hereinafter also referred to as the anode-side flow path), and a flow path through which air, i.e.,Oxidation gas flows (hereinafter also referred to as the cathode-side flow path), wherein an electrolyte membrane is inserted between the anode-side flow path and the cathode-side flow path.

[0011] The fuel tank 60 corresponds to a device for storing hydrogen to be supplied to the fuel cell 66. The fuel tank 60 is, for example, a resin tank having a fiber-reinforced plastic (FRP) layer on the outer surface of a resin liner. The FRP layer is formed by winding fibers containing a thermosetting resin around the resin liner. The fuel tank 60 includes a valve mechanism 62 disposed in a protrusion of the fuel tank 60. The valve mechanism 62 has a valve-internal flow path 34 formed therein. The valve-internal flow path 34 includes a first flow path 35, a second flow path 36, and a third flow path 37. One end of the first flow path 35 is open on a surface of the valve mechanism 62, and the filling line 30 is connected to one end of the first flow path 35.A second shutoff valve 52 is arranged in the first flow path 35. The second shutoff valve 52 allows the hydrogen to flow only in the direction from the filling line 30 toward the fuel tank 60. The other end of the first flow path 35 is connected to one end of the third flow path 37. One end of the second flow path 36 is open at the surface of the valve mechanism 62, and the supply line 32 is connected to one end of the second flow path 36. A main shutoff valve 53 is arranged in the second flow path 36. The main shutoff valve 53 corresponds to a solenoid valve that opens and closes the second flow path 36. The other end of the second flow path 36 is connected to one end of the third flow path 37. The other end of the third flow path 37 is open at the fuel tank 60.The third flow path 37, into which the first flow path 35 and the second flow path 36 flow, may not be provided, and the first flow path 35 and the second flow path 36 may communicate separately with the fuel tank 60. The fuel tank 60 further includes a temperature sensor 45 that detects the temperature in the fuel tank 60.

[0012] The receptacle 64 corresponds to a structure for connecting the hydrogen refueling device 70 to the fuel cell vehicle 20 when the fuel tank 60 is filled with hydrogen. The receptacle 64 is mounted on a side surface of a vehicle body 22 of the fuel cell vehicle 20. The receptacle 64 has a fourth flow path 38 formed therein. One end of the fourth flow path 38 is connected to the filling line 30. The other end of the fourth flow path 38 is open on a surface of the vehicle body 22 and forms a filling port 26 into which hydrogen supplied from the hydrogen refueling device 70 flows. A first check valve 51 is arranged in the fourth flow path 38. The first check valve 51 allows hydrogen to flow only in the direction from the filling port 26 toward the filling line 30.

[0013] A lid 24, which covers the receptacle 64, is provided on the vehicle body 22. The lid 24 is hinged to the vehicle body 22 so that the lid 24 can be opened and closed. The lid 24 is open when the fuel tank 60 is filled with hydrogen by the hydrogen refueling device 70. A lid sensor 46 for detecting whether the lid 24 is open or closed is mounted near the receptacle 64.

[0014] In the Fig. In the configuration shown in Figure 1, a flow path connecting the filling port 26 and the fuel tank 60, that is, a flow path through which hydrogen supplied from the filling port 26 flows into the fuel tank 60, is also referred to as the "filling flow path." In the present embodiment, the "filling flow path" includes the filling line 30, the first flow path 35, the third flow path 37, and the fourth flow path 38. In the present embodiment, a filling pressure sensor 41 and a flow rate sensor 47 are mounted on the filling line 30. The filling pressure sensor 41 detects the pressure in the filling line 30, and the flow rate sensor 47 detects the mass flow rate of hydrogen flowing in the filling line 30. The filling pressure sensor 41 is also referred to as the "first pressure sensor."

[0015] When filling the fuel tank 60 with hydrogen, a nozzle 72 of the hydrogen refueling device 70, described later, is connected to the receptacle 64, and hydrogen is supplied from the hydrogen refueling device 70 to the fuel tank 60 via the nozzle 72, the receptacle 64, and the filling flow path. At this time, since high-pressure hydrogen is supplied from the hydrogen refueling device 70, the first shutoff valve 51 and the second shutoff valve 52 are opened. When filling the fuel tank 60 with hydrogen, the main shutoff valve 53 in the valve mechanism 62 is closed. Therefore, the pressure detected by the filling pressure sensor 41 during the filling of the fuel tank 60 with fuel gas is approximately equal to the pressure in the fuel tank 60. Hereinafter, the pressure in the fuel tank 60 is also simply referred to as the "tank pressure."

[0016] In the Fig. 1, a flow path connecting the fuel cell 66 and the fuel tank 60, that is, a flow path through which hydrogen discharged from the fuel tank 60 is supplied to the fuel cell 66, is also referred to as the "supply flow path." In the present embodiment, the "supply flow path" includes the supply line 32, the second flow path 36, and the third flow path 37. A pressure reducing valve 54 and an injector 55 are mounted on the supply line 32 in this order from the upstream side of the hydrogen flow. The injector 55 has a solenoid valve therein and adjusts the amount of hydrogen supplied to the fuel cell 66 by opening and closing the solenoid valve. In order to use the fuel cell 66 to generate electricity,To initiate power, the main shutoff valve 53 is opened to cause high-pressure hydrogen to flow from the fuel tank 60 into the supply line 32. The pressure of the high-pressure hydrogen flowing in the supply line 32 is reduced by the pressure reducing valve 54 and guided by the injector 55 into the anode-side flow paths in the fuel cell 66.

[0017] In the supply flow path, a high-pressure sensor 42 is mounted between the main shutoff valve 53 and the pressure reducing valve 54, a medium-pressure sensor 43 is mounted between the pressure reducing valve 54 and the injector 55, and a low-pressure sensor 44 is mounted between the injector 55 and the fuel cell 66. During power generation of the fuel cell 66, the detection value of the high-pressure sensor 42 is the largest, followed by the detection value of the medium-pressure sensor 43 and the detection value of the low-pressure sensor 44. The detection values ​​of the high-pressure sensor 42, the medium-pressure sensor 43, and the low-pressure sensor 44 are used to control the amount of hydrogen supplied to the fuel cell 66 during power generation of the fuel cell 66. To cause the fuel cell 66 to generate electricity, the main shutoff valve 53 is opened.The pressure detected by the high-pressure sensor 42 at this time is approximately equal to the tank pressure. The high-pressure sensor 42 is mounted upstream of the pressure reducing valve 54, which corresponds to a device for reducing the fuel gas pressure, and the injector 55. The gas pressure detected by the high-pressure sensor 42 can be referred to as the "fuel gas pressure at the outlet of the fuel tank 60." The high-pressure sensor 42 is also referred to as the "second pressure sensor."

[0018] An exhaust line 39 is also connected to the fuel cell 66. The exhaust line 39 corresponds to a line through which anode exhaust gas, which has flowed through the anode-side flow paths in the fuel cell 66, is discharged from the fuel cell 66. The downstream side of the exhaust line 39 can be connected to the supply line 32 between the injector 55 and the fuel cell 66 to guide anode exhaust gas discharged from the fuel cell 66 back into the fuel cell 66. That is, a flow path for circulating fuel gas can be formed.

[0019] The control unit 68 is composed of a so-called microcomputer including a CPU that performs logical operations, a ROM, a RAM, etc. The control unit 68 receives detection signals from various sensors and performs various controls for the fuel cell vehicle 20. The various sensors include pressure sensors such as the fill pressure sensor 41, the high pressure sensor 42, the medium pressure sensor 43, and the low pressure sensor 44, the temperature sensor 45, the cap sensor 46, and the flow rate sensor 47, which are described above, as well as sensors not shown, such as an accelerator pedal position sensor, a shift position sensor, and a vehicle speed sensor. Specifically, the control unit 68 outputs drive signals to the various valves described above, the drive motor, various control devices, etc.The control unit 68 may not be a single control unit that performs all of the following controls: control of a hydrogen refueling operation, control related to pressure sensor abnormality detection, which will be described later, and control of vehicle driving. The control unit 68 may be composed of separate control units (electronic control units (ECUs)) that perform these controls separately and send and receive information to and from each other.

[0020] The hydrogen refueling device 70 corresponds to a device for filling the fuel tank 60 of the fuel cell vehicle 20 with hydrogen and can be provided, for example, at hydrogen stations. The hydrogen refueling device 70 includes a hydrogen storage unit (not shown) that stores high-pressure hydrogen, a hydrogen dispensing hose 76 that supplies high-pressure hydrogen from the hydrogen storage unit, the nozzle 72 provided at the tip end of the hydrogen dispensing hose 76, a station pressure sensor 75, and a control unit 78.The nozzle 72 corresponds to a structure that connects to the receptacle 64 of the fuel cell vehicle 20 when the fuel tank 60 is filled with hydrogen, and corresponds to a structure that connects a hydrogen flow path on the hydrogen refueling device 70 side, which is open at the nozzle 72, to the filling flow path of the fuel cell vehicle 20. The station pressure sensor 75 detects the pressure of hydrogen supplied from the hydrogen refueling device 70 to the fuel tank 60. When the nozzle 72 is connected to the receptacle 64 and a hydrogen flow path in the hydrogen refueling device 70 communicates with the fuel tank 60 to fill the fuel tank 60 with hydrogen, the station pressure sensor 75 is ready to detect the tank pressure. The control unit 78 is composed of a microcomputer including a CPU that performs logical operations, a ROM, a RAM, etc.During hydrogen filling, the control unit 78 can control the flow rate, etc., of hydrogen supplied to the fuel cell vehicle 20 using the tank pressure detected by the station pressure sensor 75. The hydrogen refueling device 70 further includes a pre-cooler (not shown) that cools hydrogen to a predetermined temperature before filling. When the fuel tank 60 is filled with hydrogen, the temperature in the fuel tank 60 increases due to a phenomenon called adiabatic compression. An excessive temperature rise in the fuel tank 60 is prevented by cooling the hydrogen before filling.

[0021] Although in Fig. 1, the fuel cell vehicle 20 and the hydrogen refueling device 70 may be provided with a communication device that transmits information about the filling of the fuel tank 60 with hydrogen, such as information including the tank pressure, between the fuel cell vehicle 20 and the hydrogen refueling device 70. Such a communication device may, for example, be a device for transmitting the above information from the fuel cell vehicle 20 to the hydrogen refueling device 70 via infrared communication. (A-2) Operation to detect an abnormality of pressure sensors

[0022] Fig. 2 is a flowchart of an abnormality detection control routine executed by the CPU of the control unit 68 of the fuel cell vehicle 20 of the present embodiment. Fig. Fig. 3 is a timing chart illustrating an overview of operations related to an abnormality detection control. The operations performed to detect an abnormality of the sensors that detect the pressure of the fuel gas, particularly an abnormality of the filling pressure sensor 41 and the high pressure sensor 42, will be explained with reference to Figs. Fig. 2 and Fig. 3 described.

[0023] The Fig. The abnormality detection control routine shown in FIG. 2 is started when the control unit 68 determines that hydrogen filling of the fuel tank 60 of the fuel cell vehicle 20 is started. In the present embodiment, the control unit 68 determines that hydrogen filling of the fuel tank 60 is started when the control unit 68 receives a signal from the lid sensor 46 indicating that the lid 24 is open. In the case where the fuel cell vehicle 20 is provided with the above communication device for communicating with the hydrogen refueling device 70, the control unit 68 can determine that hydrogen filling of the fuel tank 60 is started when the communication is started. The system of the fuel cell vehicle 20 is normally in a stopped state when hydrogen filling of the fuel tank 60 is started.That is, a start switch for starting the system, which is provided in the fuel cell vehicle 20, is turned off when the fuel tank 60 is filled with hydrogen. The control unit 68, which executes the abnormality detection control routine with the start switch turned off and the fuel cell system 25 stopped, uses a power storage device (not shown) as its power source. This power storage device is mounted on the fuel cell vehicle 20 and is different from the fuel cell 66.

[0024] When the lid 24 of the fuel cell vehicle 20 is opened and the abnormality detection control routine of Fig. 2 is started, a user performing a hydrogen refueling operation attaches the nozzle 72 of the hydrogen refueling device 70 to the receptacle 64. When the nozzle 72 is attached or secured to the receptacle 64, the hydrogen refueling device 70 begins supplying hydrogen to the fuel tank 60.

[0025] When the control unit 68 detects the start of filling of the fuel tank 60 through a signal received from the cap sensor 46 (step S100), the control unit 68 receives a detection signal from the filling pressure sensor 41 and therefore begins detecting a filling gas pressure Pi corresponding to the pressure of hydrogen supplied to the fuel tank 60 (step S130). When the nozzle 72 is attached to the receptacle 64 and the hydrogen refueling device 70 begins supplying hydrogen, the tank pressure gradually increases. As described above, the pressure detected by the filling pressure sensor 41 during the filling of the fuel tank 60 with fuel gas is approximately equal to the tank pressure. The filling gas pressure Pi is therefore considered representative of the tank pressure.

[0026] Fig. 3 illustrates how the filling gas pressure Pi and a supply gas pressure Po change and at what time the abnormality detection control is performed using the filling gas pressure Pi and the supply gas pressure Po. The filling gas pressure Pi corresponds to the gas pressure detected by the filling pressure sensor 41 mounted on the filling line 30, and the supply gas pressure Po corresponds to the gas pressure detected by the high-pressure sensor 42 mounted on the supply line 32. In Fig. 3, time t1 indicates the time at which the control unit 68 starts detecting the filling gas pressure Pi in step S130 after detecting the start of filling in step S100. Fig. 3 shows that the filling gas pressure Pi, which corresponds to the tank pressure, gradually increases after the start of filling at time t1. Since the main shut-off valve 53 of the valve mechanism 62 is closed during hydrogen filling, the supply gas pressure Po does not change even after time t1. The control, which performs the operations from step S130 to step S180 in Fig. 2, is also referred to as the “anomaly detection control”. Fig. 3 further shows that the control unit 68 starts the abnormality detection control by starting the detection of the filling gas pressure Pi in step S130 at time t1.

[0027] The control unit 68 of the present embodiment stores a maximum inflation pressure Pimax stored therein. The maximum inflation pressure Pimax corresponds to a maximum value of the inflation gas pressures Pi detected since the inflation gas pressure Pi was started to be detected in step S130. Hereinafter, the maximum inflation pressure Pimax is sometimes simply referred to as the "maximum pressure Pimax." The CPU of the control unit 68 starts detecting the inflation gas pressure Pi in step S130. When a newly detected inflation gas pressure Pi corresponds to the maximum value of the inflation gas pressures Pi detected since the inflation gas pressure Pi was started to be detected, the CPU of the control unit 68 updates the stored maximum pressure Pimax with the newly detected inflation gas pressure Pi (step S140).If in step S140 the newly detected inflation gas pressure Pi does not correspond to the maximum value of the inflation gas pressures Pi detected since the start of detection of the inflation gas pressure Pi, the CPU of the control unit 68 maintains the stored maximum pressure Pimax without updating.

[0028] In step S140, instead of updating the stored maximum pressure Pimax with the newly detected inflation gas pressure Pi, for example, the detected inflation gas pressures Pi may be stored chronologically, and the stored maximum pressure Pimax may be updated with the average value of a plurality of recently detected inflation gas pressures Pi. The stored maximum pressure Pimax may be updated with a value obtained by averaging fluctuations of the detected inflation gas pressures Pi before and after the actually measured maximum value of the inflation gas pressure Pi, such as the average value described above.

[0029] After step S140, the CPU of the control unit 68 determines whether the process of filling the fuel tank 60 with hydrogen (hereinafter sometimes referred to as the filling process or filling) has ended (step S150). When the filling process by the hydrogen refueling device 70 progresses and finally substantially stops, the user performing the hydrogen refueling process removes the nozzle 72 of the hydrogen refueling device 70 from the receptacle 64 and closes the lid 24. In step S150, the CPU of the control unit 68 of the present embodiment determines that the filling process is ended when the CPU of the control unit 68 receives a signal from the lid sensor 46 indicating that the lid 24 is closed.

[0030] If the CPU of the control unit 68 determines that the filling operation is not completed (step S150: NO), the routine returns to step S140, and the CPU of the control unit 68 repeatedly detects the filling gas pressure Pi and repeats the process of updating the stored maximum pressure Pimax with a newly detected maximum pressure Pimax. The CPU of the control unit 68 repeats this process of updating the maximum pressure Pimax as long as the tank pressure continues to rise during filling by the hydrogen refueling device 70. For example, the filling gas pressure Pi reaches its maximum value when the fuel tank 60 becomes completely full, and thus the filling operation by the hydrogen refueling device 70 is essentially stopped. The maximum pressure Pimax is therefore fixed at this time. Fig. 3, time t2 indicates the time at which the filling process by the hydrogen refueling device 70 is substantially stopped, that is, the time at which the hydrogen refueling device 70 stops supplying hydrogen to the fuel tank 60. As described above, after the filling process by the hydrogen refueling device 70 is substantially stopped, the nozzle 72 of the hydrogen refueling device 70 is removed from the receptacle 64 and the lid 24 is closed. The CPU of the control unit 68 therefore determines that the filling process is complete. Fig. 3, time t3 indicates the time at which the lid 24 is closed and the CPU of the control unit 68 determines that the filling operation is completed. Since the receptacle 64 is provided with the first shutoff valve 51, the filling gas pressure Pi, which corresponds to the gas pressure detected by the filling pressure sensor 41, is approximately equal to the maximum pressure Pimax even after time t2 when the filling operation by the hydrogen refueling device 70 is substantially stopped. Specifically, as the hydrogen gas temperature in the fuel tank 60 gradually decreases, the filling gas pressure Pi decreases slowly.

[0031] If the CPU of the control unit 68 determines that the filling process is complete (step S150: YES), the CPU of the control unit 68 determines whether the fuel cell vehicle 20 is started (step S160). Specifically, the CPU of the control unit 68 determines whether the start switch provided in the fuel cell vehicle 20 is turned on. If the fuel cell vehicle 20 is not started (step S160: NO), the CPU of the control unit 68 repeats step S160 until it determines that the fuel cell vehicle 20 is started. When the start switch is turned on and the fuel cell system 25 is started, the main shutoff valve 53 of the valve mechanism 62 is opened to begin supplying hydrogen from the fuel tank 60 to the fuel cell 66. Fig. 3, time t4 indicates the time at which the fuel cell system 25 is started. When the main shutoff valve 53 is opened at time t4, the supply gas pressure Po quickly rises to the tank pressure. In the case where the time period from time t3 to time t4 is relatively short, the tank pressure at the time the fuel cell system 25 is started is approximately equal to the tank pressure at the time the filling operation is completed. Accordingly, in this case, the supply gas pressure Po at time t4 is approximately equal to the maximum pressure Pimax stored at the time the filling operation is completed.

[0032] When the CPU of the control unit 68 determines that the fuel cell vehicle 20 has started (step S160: YES), the CPU of the control unit 68 receives a detection signal from the high-pressure sensor 42 and therefore detects the supply gas pressure Po, that is, the pressure of hydrogen supplied from the fuel tank 60 to the fuel cell 66 (step S170). The supply gas pressure Po detected in step S170 corresponds to the value of the supply gas pressure Po detected by the high-pressure sensor 42 when the supply of hydrogen from the fuel tank 60 to the fuel cell 66 is first started after the filling operation is completed, and is also referred to as the "supply start pressure." The CPU of the control unit 68 then determines whether there is an abnormality in the pressure sensors by comparing the maximum pressure Pimax stored in step S140 with the supply gas pressure Po detected in step S170 (step S180).The CPU of the control unit 68 thus terminates this routine. Fig. 3 shows that the anomaly detection control is terminated at time t4.

[0033] In step S180, the CPU of the control unit 68 determines that both the filling pressure sensor 41 and the high-pressure sensor 42 are normal when the difference between the maximum pressure Pimax and the supply gas pressure Po is equal to or less than a predetermined reference value. If the difference between the maximum pressure Pimax and the supply gas pressure Po is greater than the reference value, the CPU of the control unit 68 determines that there is a possibility that the filling pressure sensor 41 and / or the high-pressure sensor 42 may be abnormal. The reference value is set in advance in consideration of the detection accuracy of the filling pressure sensor 41 and the high-pressure sensor 42.The reference value is set in advance to the maximum value of the possible differences between the detection value of the filling pressure sensor 41 and the detection value of the high-pressure sensor 42 that can be obtained when the tank pressure of the fully full fuel tank 60 is individually measured by the filling pressure sensor 41 and the high-pressure sensor 42 when both the filling pressure sensor 41 and the high-pressure sensor 42 are normal. If the CPU of the control unit 68 determines in step S180 that the difference between the maximum pressure Pimax and the supply gas pressure Po is greater than the reference value, there is a possibility that the high-pressure sensor 42 mounted on the supply pipe 32 may be abnormal. In this case, the CPU of the control unit 68 may prohibit movement of the fuel cell vehicle 20.

[0034] According to the fuel cell system 25 of the present embodiment configured as described above, even in the case where the pressure in the filling flow path decreases after the fuel tank 60 is filled with hydrogen, since the airtightness of the first shutoff valve 51 is impaired by, for example, foreign matter caught in the receptacle 64, the possibility that the pressure sensors may be erroneously determined to be abnormal is reduced. In the case where there is no such problem with the receptacle 64, etc., the filling gas pressure Pi is approximately the same during the period from time t2 when the filling operation is substantially stopped to time t3 when the CPU of the control unit 68 determines that the filling operation is completed.Accordingly, for example, the CPU of the control unit 68 can also determine whether there is an abnormality in the pressure sensors by comparing the filling gas pressure Pi obtained from the filling pressure sensor 41 at time t3 with the supply gas pressure Po obtained from the high-pressure sensor 42 at time t4, that is, at the next start-up of the fuel cell system 25, in a manner similar to the embodiment. However, in the case where such a problem exists in the receiver 64, etc., the filling gas pressure Pi, which corresponds to the pressure in the filling pipe 30, decreases during the period from time t2 when the filling operation is substantially stopped to time t3. In . Fig. 3 is shown by a dashed line how the filling gas pressure Pi gradually decreases after time t2.

[0035] In this case, the filling gas pressure Pi detected at time t3 when the CPU of the control unit 68 determines that the filling operation is completed is lower than the tank pressure detected at time t2 when the filling operation is substantially stopped. When the CPU of the control unit 68 determines whether there is an abnormality in the pressure sensors by comparing the filling gas pressure Pi detected at time t3 with the supply gas pressure Po detected at time t4, the difference between the filling gas pressure Pi and the supply gas pressure Po is correspondingly large, and therefore the CPU of the control unit 68 can determine that there is an abnormality in the filling pressure sensor 41 and the high pressure sensor 42 even if both sensors are normal.The detection value of the filling pressure sensor 41 used in the present embodiment is not the value of the filling gas pressure Pi detected when the CPU of the control unit 68 determines that the filling operation is completed, but the maximum pressure Pimax corresponding to the maximum value of the filling gas pressures Pi detected during the filling. The above maximum pressure Pimax is considered to be substantially equal to the pressure in the fuel tank 60 at the time when the filling operation is substantially stopped. Accordingly, the possibility of the pressure sensors being erroneously determined to be abnormal is reduced, even in the case where the pressure in the filling flow path decreases after the fuel tank 60 is filled with hydrogen.The filling gas pressure Pi decreases during the period from time t2 to time t3 not only in the case where the airtightness is impaired at the receptacle 64 as described above, but also in the case where airtightness is impaired at any point in the filling flow path after the fuel tank 60 is filled with hydrogen. B. Second embodiment

[0036] In the first embodiment, the abnormality detection control which performs the operations from step S130 to step S180 of Fig. 2, is started at time t1 when filling is started. However, the present disclosure may have different configurations. Examples in which the timing at which the abnormality detection control is started is different from the first embodiment will be described below in the second to fourth embodiments. Since the fuel cell systems 25 of the second to fifth embodiments described below have a configuration similar to that of the first embodiment, the same portions as those of the first embodiment are denoted by the same symbols as those of the first embodiment, and a detailed description thereof will be omitted.

[0037] Fig. Figure 4 is a graph showing the relationship between the filling time for filling the fuel tank 60 with hydrogen and the pressure loss and the filling flow rate. The filling time on the abscissa corresponds to the elapsed time from time t1 of Fig. 3, when filling is started. The pressure loss corresponds to the pressure loss that occurs when fuel gas flows through the filling line 30 and refers to the pressure loss that occurs between the part of the filling line 30 where the filling pressure sensor 41 is mounted and the fuel tank 60. The filling flow rate corresponds to the flow rate of the fuel gas flowing through the filling flow path. As shown in Fig. 4, the pressure loss and the filling flow rate in the filling line 30 when filling the fuel tank 60 with hydrogen show a tendency to increase for a while after the start of filling, but thereafter a tendency to decrease.

[0038] When the hydrogen refueling device 70 fills the fuel tank 60 with hydrogen, the hydrogen refueling device 70 maintains a constant pressure increase rate, but the increase in tank pressure gradually slows down. Accordingly, the flow velocity and filling flow rate of the hydrogen flowing in the filling flow path increase for a while after the start of filling, but then decrease. It is assumed that the pressure loss is influenced by a loss in a straight line, including a friction force generated between the gas and the wall surface of the flow path, a contraction loss, and a bending loss, among other things.In the present embodiment, it is assumed that the pressure loss is greatly influenced by the pipe resistance resulting from the above losses, and in particular, by the flow rate of hydrogen, which is a compressible fluid. Accordingly, as shown in FIG. Fig. 4, the pressure loss and the filling flow rate have a certain pattern determined by filling conditions such as the temperature of the fuel gas supplied from the hydrogen refueling device 70, the piping shape of the filling flow path, and the state of pressure control during filling.

[0039] A pressure loss threshold corresponding to a reference value used to determine that the pressure loss during filling is sufficiently reduced can be set as in Fig. 4. This pressure loss threshold corresponds to a value indicating that even if the detection value of the filling pressure sensor 41 becomes higher than an actual tank pressure due to the pressure loss, the pressure loss is reduced to such an extent that the detection value of the filling pressure sensor 41 does not become greater than the tank pressure at the end of filling. This pressure loss threshold may change depending on the accuracy of the filling pressure sensor 41 and the high-pressure sensor 42 to be used, structural factors that affect the above friction force, such as the shape of the filling pipe, conditions during filling, etc., and may be determined in advance according to the configuration of the fuel cell system 25. The pressure loss threshold is also referred to as the "determination value."

[0040] The system configuration of the fuel cell system 25 of the present embodiment is simplified by using the detection value of the filling pressure sensor 41 mounted on the filling pipe 30 as the tank pressure, rather than mounting a pressure sensor directly on the fuel tank 60. Therefore, it is difficult to detect the pressure loss during filling. In the second embodiment, the filling flow rate (mass flow rate) detected by the flow rate sensor 47 is used to determine whether the pressure loss during filling is estimated to be sufficiently reduced, that is, whether the pressure loss during filling is reduced to the pressure loss threshold.

[0041] As described above, the pressure loss and the filling flow rate show a certain pattern, as shown in Fig. 4, according to the pressure control state during filling, etc. Such a relationship between the pressure loss and the filling flow rate can be obtained in advance experimentally or through simulations. In the second embodiment, a reference flow rate Fa is determined in advance using the above-described relationship between the pressure loss and the filling flow rate. The reference flow rate Fa corresponds to a reference value of the filling flow rate, which is used to determine whether the pressure loss during filling is reduced to the pressure loss threshold. Fig. Figure 4 shows that the filling flow rate at the filling time tα, when the pressure loss decreases to the pressure loss threshold, is determined as the reference flow rate Fa. The reference flow rate Fa is determined by the value of the set pressure loss threshold and the relationship between the pressure loss and the filling flow rate. For example, the reference flow rate Fa can be set to 30 g / s.

[0042] Fig. 5 is a flowchart of an abnormality detection control routine executed by the CPU of the control unit 68 of the fuel cell vehicle 20 of the second embodiment. Fig. Fig. 6 is a timing chart showing an overview of operations related to the abnormality detection control. The operations performed to detect an abnormality of the inflation pressure sensor 41 and the high pressure sensor 42 will be explained with reference to Figs. Fig. 5 and Fig. 6. In Fig. 5 the same steps as these in Fig. 2 with the same step numbers.

[0043] The control unit 68 executes the abnormality detection control routine according to Fig. 5 instead of the anomaly detection control routine of the Fig. 2. When the CPU of the control unit 68 of the second embodiment detects the start of hydrogen filling of the fuel tank 60 (step S100), the CPU of the control unit 68 receives a detection signal from the flow rate sensor 47 and therefore begins monitoring a filling flow rate F (step S102). The filling flow rate F corresponds to the flow rate of hydrogen supplied to the fuel tank 60.

[0044] Similar to Fig. 3 represents Fig. 6 shows how the filling gas pressure Pi and the supply gas pressure Po change and at what time the abnormality detection control is performed using the filling gas pressure Pi and the supply gas pressure Po. Fig. 6 also illustrates how the filling flow rate F changes. In Fig. 6 is the pattern in which the filling flow rate F changes, compared to Fig. 4 is shown in simplified form. In the second embodiment, unlike the first embodiment, the abnormality detection control with detection of the filling gas pressure Pi is not started at time t1 when the start of filling is detected in step S100, as shown in Fig. 6 is shown.

[0045] After the CPU of the control unit 68 starts monitoring the filling flow rate F in step S102, the CPU of the control unit 68 determines whether a change in the filling flow rate F changes from increasing to decreasing over time (step S104). That is, after step S102, the CPU of the control unit 68 repeatedly performs the process of obtaining the detection value of the flow rate sensor 47 and determines whether the amount of change in the filling flow rate F, which corresponds to the difference between the current and previous detection values ​​of the flow rate sensor 47, changes from a state where the difference continues to be a positive value to a state where the difference continues to be a negative value.The CPU of the control unit 68 repeats the process of step S104 as long as the CPU of the control unit 68 determines that the change in the filling flow rate F does not transition from an increase to a decrease with time (step S104: NO).

[0046] If the CPU of the control unit 68 determines that the change in the filling flow rate F changes from increasing to decreasing over time (step S104: YES), the CPU of the control unit 68 compares the filling flow rate F with the above-described reference flow rate Fa (step S106). That is, after step S104, the CPU of the control unit 68 repeats the process of obtaining the detection value of the flow rate sensor 47 and comparing the obtained filling flow rate F with the reference flow rate Fa. The CPU of the control unit 68 repeats the process of step S106 as long as the CPU of the control unit 68 determines that the obtained filling flow rate F is higher than the reference flow rate Fa (step S106: NO).

[0047] If the CPU of the control unit 68 determines that the obtained filling flow rate F is equal to or less than the reference flow rate Fa (step S106: YES), the CPU of the control unit 68 executes the abnormality detection control including the operations of steps S130 to S180, which is similar to the abnormality detection control of the first embodiment. The CPU of the control unit 68 then ends this routine. That is, the CPU of the control unit 68 begins by detecting the filling gas pressure Pi and obtains the maximum pressure Pimax, and determines whether there is an abnormality in the pressure sensors by comparing the maximum pressure Pimax with the supply gas pressure Po. Fig. 6, the time tα indicates the time at which the CPU of the control unit 68 determines that the obtained filling flow rate F is equal to or less than the reference flow rate Fa. Fig. 6 further shows that the anomaly detection control is started at time tα.

[0048] This configuration improves the accuracy of abnormality determination for the pressure sensors, in addition to providing effects similar to those of the first embodiment. That is, the value of the filling gas pressure Pi detected when the pressure loss in the filling flow path is high is less likely to be stored as the maximum pressure Pimax, which is higher than the tank pressure at the end of filling. Accordingly, the possibility of the pressure sensors being erroneously determined to be abnormal even though the pressure sensors are normal is reduced because the maximum pressure Pimax is higher than the supply gas pressure Po.

[0049] During filling, with increasing pressure loss in the filling flow path, the pressure detected by the filling pressure sensor 41 as the tank pressure becomes higher than the actual pressure in the fuel tank 60. In this case, when determining whether there is an abnormality in the pressure sensors using the maximum pressure Pimax derived from the detection values ​​of the filling pressure sensor 41, there is a possibility that the value detected by the filling pressure sensor 41 at a large pressure loss during filling may be derived as the maximum pressure Pimax instead of a true or actual maximum pressure at the end of filling of the fuel tank 60. When determining whether there is an abnormality in the pressure sensors using the pressure higher than the true maximum pressure at the end of filling as the maximum pressure Pimax (step S180 in Fig. 2), the pressure sensors may be erroneously determined to be abnormal even if the pressure sensors are normal because the maximum pressure Pimax is higher than the supply gas pressure Po determined in step S170. In the fuel cell system 25 of the second embodiment, the detection of the filling gas pressure Pi, which is performed to obtain the maximum pressure Pimax, is started after the pressure loss during filling is judged to have decreased sufficiently. Accordingly, the possibility of such an erroneous abnormality determination is reduced even if the pressure loss during filling increases. C. Third embodiment

[0050] In the third embodiment, abnormality detection control for the pressure sensors is performed with an update of the maximum pressure Pimax after the pressure loss during filling is estimated to be sufficiently reduced, as in the second embodiment. In the third embodiment, the increase rate of the filling gas pressure Pi detected by the filling pressure sensor 41 (hereinafter also referred to as the pressure increase rate ΔPi) is used to determine whether the pressure loss during filling has reduced to the pressure loss threshold. In the present embodiment, the pressure increase rate ΔPi corresponds to an increase in the filling gas pressure Pi per unit time. However, the pressure increase rate ΔPi may, for example, correspond to the ratio of the present detection value to the previous detection value of the filling gas pressure Pi detected at regular intervals.

[0051] Fig. Figure 7 is a graph showing the relationship between the filling time for filling the fuel tank 60 with hydrogen and the pressure loss and the pressure increase rate. The filling time and the pressure loss are related to these Fig. 4 of the second embodiment. The pressure increase rate corresponds to the rate of increase or increase in the pressure of the fuel gas flowing through the filling flow path, as described above. As in Fig. As shown in Figure 7, when filling the fuel tank 60 with hydrogen, the pressure loss and the pressure increase rate tend to increase for a certain period of time after the start of filling, but then tend to decrease. As described above, this is because the hydrogen refueling device 70 maintains a constant pressure increase rate when filling the fuel tank 60 with hydrogen, but the pressure increase in the fuel tank 60 gradually slows down. Accordingly, as shown in Figure 7, Fig. 7, the pressure loss and the pressure increase rate have a certain pattern which is determined by filling conditions such as the temperature of the fuel gas supplied from the hydrogen refueling device 70, the piping shape of the filling flow path and the pressure control state during filling.

[0052] Such a relationship between the pressure loss and the pressure increase rate can be obtained in advance experimentally or through simulations. In the third embodiment, a reference rate ΔPia is determined in advance using this relationship between the pressure loss and the pressure increase rate. The reference rate ΔPia corresponds to a reference value of the pressure increase rate, which is used to determine whether the pressure loss during filling has been reduced to the pressure loss threshold. Fig. Figure 7 shows that the pressure increase rate at the filling time tβ, when the pressure loss drops to the pressure loss threshold, is determined as the reference rate ΔPia. The reference rate ΔPia is determined by the value of the set pressure loss threshold and the relationship between the pressure loss and the pressure increase rate. Such a reference rate ΔPia can, for example, be set to 23 MPa / min. The reference rate ΔPia is also referred to as the "first reference rate."

[0053] Fig. 8 is a flowchart of an abnormality detection control routine executed by the CPU of the control unit 68 of the fuel cell vehicle 20 of the third embodiment. Fig. Fig. 9 is a timing chart showing an overview of operations related to an abnormality detection control. The operations performed to detect an abnormality of the inflation pressure sensor 41 and the high pressure sensor 42 will be explained with reference to Figs. Fig. 8 and Fig. 9. In Fig. 8 are the same steps as these of Fig. 2 with the same step numbers.

[0054] The control unit 68 executes the anomaly detection control routine of Fig. 8 instead of the Fig. 2. When the CPU of the control unit 68 of the third embodiment detects the start of hydrogen filling of the fuel tank 60 (step S100), the CPU of the control unit 68 receives a detection signal from the filling pressure sensor 41 and begins monitoring the pressure increase rate ΔPi (step S112). The pressure increase rate Pi corresponds to the rate of increase in pressure in the filling flow path.

[0055] Similar to Fig. 3 represents Fig. 9 shows how the filling gas pressure Pi and the supply gas pressure Po change and at what time anomaly detection control is performed using the filling gas pressure Pi and the supply gas pressure Po. Fig. 9 also illustrates how the pressure increase rate ΔPi changes. In Fig. 9 is the pattern in which the pressure increase rate ΔPi changes compared to Fig. 7 is shown in simplified form. In the third embodiment, unlike the first embodiment, the abnormality detection control is not started at time t1 when the start of filling is detected in step S100, as shown in Fig. 9 is shown.

[0056] After the CPU of the control unit 68 starts monitoring the pressure increase rate ΔPi in step S112, the CPU of the control unit 68 determines whether a change in the pressure increase rate ΔPi over time changes from an increase to a decrease (step S114). That is, after step S112, the CPU of the control unit 68 repeatedly performs the process of obtaining the detection value of the inflation pressure sensor 41 and calculating the pressure increase rate ΔPi, and determines whether the amount of change in the pressure increase rate ΔPi, which corresponds to the difference between the current and previous pressure increase rates ΔPi, changes from a state where the difference continuously assumes a positive value or continues with a positive value to a state where the difference continuously assumes a negative value or continues with a negative value.The CPU of the control unit 68 repeats the process of step S114 as long as the CPU of the control unit 68 determines that the change in the pressure increase rate ΔPi over time does not change from an increase to a decrease (step S114: NO).

[0057] If the CPU of the control unit 68 determines that the change in the pressure increase rate ΔPi over time changes from increasing to decreasing (step S114: YES), the CPU of the control unit 68 compares the calculated pressure increase rate ΔPi with the above-described reference rate ΔPia (step S116). That is, after step S114, the CPU of the control unit 68 repeats the process of obtaining the detection value of the inflation pressure sensor 41, calculating the pressure increase rate ΔPi, and comparing the calculated pressure increase rate ΔPi with the reference rate ΔPia. The CPU of the control unit 68 repeats the process of step S116 as long as the CPU of the control unit 68 determines that the calculated pressure increase rate ΔPi is higher than the reference rate ΔPia (step S116: NO).

[0058] If the CPU of the control unit 68 determines that the calculated pressure increase rate ΔPi is equal to or lower than the reference rate ΔPia (step S116: YES), the CPU of the control unit 68 executes the abnormality detection control including the operations of steps S130 to S180, which is similar to the abnormality detection control of the first embodiment. The CPU of the control unit 68 then ends this routine. That is, the CPU of the control unit 68 begins detecting the filling gas pressure Pi and updates the maximum pressure Pimax, and determines whether an abnormality exists in the pressure sensors by comparing the maximum pressure Pimax with the supply gas pressure Po. Fig. 9, the time tβ indicates the time at which the CPU of the control unit 68 determines that the calculated pressure increase rate ΔPi is equal to or lower than the reference rate ΔPia. Fig. 9 further shows that the anomaly detection control is started at time tβ.

[0059] This configuration further improves the accuracy of abnormality determination for the pressure sensors, in addition to effects similar to those of the first embodiment. That is, the value of the filling gas pressure Pi detected when there is a high pressure loss in the filling flow path is less likely to be stored as the maximum pressure Pimax, which is higher than the tank pressure at the end of filling. Accordingly, the possibility of the pressure sensors being erroneously determined to be abnormal even though the pressure sensors are normal is reduced because the maximum pressure Pimax is higher than the supply gas pressure Po.

[0060] In the third embodiment described above, the detection value of the filling pressure sensor 41 is used in monitoring the pressure increase rate ΔPi in steps S112 to S116. However, the present disclosure may have a different configuration. For example, if the fuel cell vehicle 20 can obtain the detection value of the station pressure sensor 75 of the hydrogen refueling device 70 through communication between the fuel cell vehicle 20 and the hydrogen refueling device 70, the fuel cell vehicle 20 can monitor the pressure increase rate ΔPi using the detection value of the station pressure sensor 75. D. Fourth embodiment

[0061] In the fourth embodiment, abnormality detection control for the pressure sensors including updating the maximum pressure Pimax is performed after the pressure loss during filling is judged to be sufficiently reduced, as in the second embodiment. In the fourth embodiment, the rate of increase of the temperature Tx in the fuel tank 60 detected by the temperature sensor 45 is used to determine whether the pressure loss during filling has reduced to the pressure loss threshold. The rate of increase of the temperature Tx in the fuel tank 60 is also referred to as the “tank temperature increase rate” or the “temperature increase rate ΔTx.” In the present embodiment, the temperature increase rate ΔTx corresponds to an increase in the tank temperature Tx per unit time. However, the temperature increase rate ΔTx may, for example, be the ratio of the present or future pressure to the pressure loss.current detection value to the previous detection value of the tank temperature Tx, which is detected at regular intervals.

[0062] Fig. Figure 10 is a graph showing the relationship between the filling time for filling the fuel tank 60 with hydrogen and the pressure loss and the temperature increase rate. The filling time and the pressure loss are related to these Fig. 4 of the second embodiment. The temperature increase rate corresponds to the increase rate of the temperature in the fuel tank 60 as described above. As in Fig. As shown in Figure 10, the pressure loss and the temperature increase rate when filling the fuel tank 60 with hydrogen tend to increase for a certain time after the start of filling, but then tend to decrease. As described above, when filling the fuel tank 60 with hydrogen, the temperature in the fuel tank 60 increases due to a phenomenon such as adiabatic compression. The temperature increase rate in the fuel tank 60 increases with the increase in the flow rate of the fuel gas supplied to the fuel tank 60 through the filling flow path, that is, the filling flow rate. As described above, the filling flow rate increases for a while after the start of filling and then decreases. Accordingly, the temperature increase rate of the fuel tank 60 increases for a while after the start of filling and then decreases. As shown in Fig. 10, the pressure loss and the temperature increase rate show a certain pattern which is determined by filling conditions such as the temperature of the fuel gas supplied from the hydrogen refueling device 70, the piping shape of the filling flow path and the pressure control state during filling.

[0063] The relationship between pressure loss and temperature increase rate described above can be obtained in advance experimentally or through simulations. In the fourth embodiment, a reference rate ΔTxa is determined in advance using this relationship between pressure loss and temperature increase rate. The reference rate ΔTxa corresponds to a reference value of the temperature increase rate, which is used to determine whether the pressure loss during filling has decreased to the pressure loss threshold. Fig. Figure 10 shows that the temperature increase rate at the filling time tγ, when the pressure loss drops to the pressure loss threshold, is determined as the reference rate ΔTxa. The reference rate ΔTxa is determined by the value of the set pressure loss threshold and the relationship between the pressure loss and the temperature increase rate. Such a reference rate ΔTxa can be set, for example, to 20 °C / min. The reference rate ΔTxa is also referred to as the "second reference rate."

[0064] Fig. 11 is a flowchart of an abnormality detection control routine executed by the CPU of the control unit 68 of the fuel cell vehicle 20 of the fourth embodiment. Fig. Fig. 12 is a timing chart showing an overview of operations related to the abnormality detection control. The operations performed to detect an abnormality of the inflation pressure sensor 41 and the high pressure sensor 42 will be explained with reference to Figs. Fig. 11 and Fig. 12. In Fig. 11 the same steps as these of Fig. 2 with the same step numbers.

[0065] The control unit 68 executes the anomaly detection control routine of Fig. 11 instead of the Fig. 2. When the CPU of the control unit 68 of the fourth embodiment detects the start of hydrogen filling of the fuel tank 60 (step S100), the CPU of the control unit 68 receives a detection signal from the temperature sensor 45, that is, the temperature detected by the temperature sensor 45, and therefore begins monitoring the temperature increase rate ΔTx (step S122). The temperature increase rate ΔTx corresponds to the temperature increase rate in the fuel tank 60.

[0066] Similar to Fig. 3 represents Fig. 12 shows how the filling gas pressure Pi and the supply gas pressure Po change and at what time the abnormality detection control is performed using the filling gas pressure Pi and the supply gas pressure Po. Fig. 12 also illustrates how the temperature increase rate ΔTx changes. In Fig. 12 is the pattern in which the temperature increase rate ΔTx changes compared to Fig. 10 is shown in simplified form. In the fourth embodiment, unlike the first embodiment, the abnormality detection control is not started at time t1 when the start of filling is detected in step S100, as shown in Fig. 12 is shown.

[0067] After the CPU of the control unit 68 starts monitoring the temperature increase rate ΔTx in step S122, the CPU of the control unit 68 determines whether a change in the temperature increase rate ΔTx over time changes from increasing to decreasing (step S124). That is, after step S122, the CPU of the control unit 68 repeatedly performs the process of obtaining the detection value of the temperature sensor 45 and calculating the temperature increase rate ΔTx, and determines whether the amount of change in the temperature increase rate ΔTx, which corresponds to the difference between the current and previous temperature increase rates ΔTx, changes from a state where the difference continuously assumes a positive value to a state where the difference continuously assumes a negative value.The CPU of the control unit 68 repeats the process of step S124 as long as the CPU of the control unit 68 determines that the change in the temperature increase rate ΔTx with time does not change from an increase to a decrease (step S124: NO).

[0068] If the CPU of the control unit 68 determines that the change in the temperature increase rate ΔTx over time is changing from increasing to decreasing (step S124: YES), the CPU of the control unit 68 compares the calculated temperature increase rate ΔTx with the above-described reference rate ΔTxa (step S126). That is, after step S124, the CPU of the control unit 68 repeats the process of obtaining the detection value of the temperature sensor 45, calculating the temperature increase rate ΔTx, and comparing the calculated temperature increase rate ΔTx with the reference rate ΔTxa. The CPU of the control unit 68 repeats the process of step S126 as long as the CPU of the control unit 68 determines that the calculated temperature increase rate ΔTx is higher than the reference rate ΔTxa (step S126: NO).

[0069] If the CPU of the control unit 68 determines that the calculated temperature increase rate ΔTx is equal to or lower than the reference rate ΔTxa (step S126: YES), the CPU of the control unit 68 executes the abnormality detection control including the operations of steps S130 to S180, which is similar to the abnormality detection control of the first embodiment. The CPU of the control unit 68 then terminates this routine. That is, the CPU of the control unit 68 starts detecting the filling gas pressure Pi and updates the maximum pressure Pimax, and determines whether an abnormality exists in the pressure sensors by comparing the maximum pressure Pimax with the supply gas pressure Po. Fig. 12, the time tγ indicates the time at which the CPU of the control unit 68 determines that the calculated temperature increase rate ΔTx is equal to or lower than the reference rate ΔTxa. Fig. 12 further shows that the anomaly detection control is started at time tγ.

[0070] This configuration, in addition to the effects similar to those of the first embodiment, further improves the accuracy of abnormality determination for the pressure sensors. That is, the value of the filling gas pressure Pi detected when the pressure loss in the filling flow path is high is less likely to be stored as the maximum pressure Pimax, which is higher than the tank pressure at the end of filling. Accordingly, the possibility of the pressure sensors being erroneously determined to be abnormal even though the pressure sensors are normal is reduced because the maximum pressure Pimax is higher than the supply gas pressure Po. E. Fifth Embodiment

[0071] In the first to fourth embodiments, it is determined whether there is an abnormality in the pressure sensors based on the difference between the supply gas pressure Po, that is, the supply start pressure, and the maximum filling pressure Pimax. However, the present disclosure may have a different configuration. In the fifth embodiment, it is determined whether there is an abnormality in the pressure sensors based on the difference between the fuel gas amount in the fuel tank 60 at the start of the fuel gas supply to the fuel cell 66 and the fuel gas amount in the fuel tank 60 at the time when the filling gas pressure Pi is the maximum value, that is, the difference between the fuel gas amount in the fuel tank 60 at the time when the supply of hydrogen to the fuel cell 66 is first started after the filling is completed and the fuel gas amount in the fuel tank 60 at the time when the detection value of the filling gas pressure Pi becomes the maximum.The process of determining whether there is an abnormality in the pressure sensors using the difference between the fuel gas amounts is applicable to any of the first to fourth embodiments.

[0072] In the fifth embodiment, when updating the maximum pressure Pimax in step S140 of the above embodiments, the CPU of the control unit 68 also stores the temperature in the fuel tank 60, that is, the value detected by the temperature sensor 45, at the time the maximum pressure Pimax is detected to update the stored maximum pressure Pimax. When detecting the supply gas pressure Po corresponding to the supply start pressure in step S170, the CPU of the control unit 68 also detects the temperature in the fuel tank 60, that is, the value detected by the temperature sensor 45, at the time this supply gas pressure Po is detected.

[0073] In step S180, the CPU of the control unit 68 calculates the amount of fuel gas in the fuel tank 60 at the time when the filling gas pressure Pi is at its maximum, using the temperature in the fuel tank 60 at the time when the filling gas pressure Pi is at its maximum, that is, the temperature in the fuel tank 60 at the time when the stored maximum pressure Pimax is detected, and the stored maximum pressure Pimax. In step S180, the CPU of the control unit 68 also calculates the amount of fuel gas in the fuel tank 60 at the start of fuel gas supply to the fuel cell 66, using the supply gas pressure Po detected in step S170 and the temperature in the fuel tank 60 at the time this supply gas pressure Po is detected.the capacity of the fuel tank 60 is stored in advance in the control unit 68, and the CPU of the control unit 68 can calculate the amount of fuel gas or the amount of fuel gas in the fuel tank 60, in particular the amount of hydrogen in the fuel tank 60, from the pressure and temperature in the fuel tank 60 and the capacity of the fuel tank 60.

[0074] As described above, in step S180 of the fifth embodiment, the CPU of the control unit 68 calculates the fuel gas amount in the fuel tank 60 at the start of fuel gas supply to the fuel cell 66 and the fuel gas amount in the fuel tank 60 at the time when the filling gas pressure Pi is maximum, and determines that both the filling pressure sensor 41 and the high-pressure sensor 42 are normal when the difference between the calculated fuel gas amounts in the fuel tank 60 is equal to or less than a predetermined reference value. If the above difference is greater than the reference value, the CPU of the control unit 68 determines that there is a possibility that the filling pressure sensor 41 and / or the high-pressure sensor 42 may be abnormal. The reference value is set in advance in consideration of the detection accuracy of the filling pressure sensor 41 and the high-pressure sensor 42 and the detection accuracy of the temperature sensor 45.The reference value is set in advance to the maximum value of possible differences between the fuel gas amount in the fuel tank 60 calculated when the fuel gas supply to the fuel cell 66 is started after the fuel tank 60 is fully filled, and the fuel gas amount in the fuel tank 60 calculated from the detection value at the time when the filling gas pressure Pi is maximum and the fuel tank 60 is fully filled. The possible differences correspond to the differences that can be obtained when both the filling pressure sensor 41 and the high pressure sensor 42 are normal.

[0075] The above fuel gas quantities calculated to obtain the difference in step S180 of the present embodiment correspond to the absolute fuel gas quantities in the fuel tank 60, which are calculated using the pressure and temperature in the fuel tank 60. These fuel gas quantities can be calculated, for example, as the molar amounts of hydrogen in the fuel tank 60 or as the weights of hydrogen in the fuel tank 60.

[0076] In addition to the effects similar to those of the above embodiments, this configuration improves the accuracy of abnormality determination for the pressure sensors even when the time period from time t3 when it is determined that the filling operation is completed to time t4 when the fuel cell system 25 is subsequently started is relatively long. As described above, when the fuel tank 60 is filled with hydrogen, the temperature in the fuel tank 60 increases due to a phenomenon such as adiabatic compression. After the filling operation is completed, the temperature in the fuel tank 60 gradually decreases due to heat dissipation, etc. Accordingly, the pressure in the fuel tank 60 may decrease with the decrease in the temperature in the fuel tank 60 while the fuel cell system 25 is stopped.In the fifth embodiment, the fuel gas quantities in the fuel tank 60 are calculated and compared to determine whether the pressure sensors are normal. The configuration of the fifth embodiment thus reduces the influence of the pressure drop in the fuel tank 60 on the abnormality determination for the pressure sensors and improves the accuracy of the determination. F. Further embodiments

[0077] (F1) In the above embodiments, the fuel cell system 25 includes a single fuel tank 60. However, the fuel cell system 25 may include a plurality of fuel tanks 60. In this case, for example, the fuel tanks 60 are connected in parallel, and the operation of filling the fuel tank 60 with hydrogen and the operation of supplying hydrogen from the fuel tank 60 to the fuel cell 66 are performed simultaneously in all the fuel tanks 60.

[0078] The filling pressure sensor 41 for detecting the filling gas pressure Pi and the flow rate sensor 47 for detecting the mass flow rate of hydrogen flowing through the filling line 30 are mounted on the filling line 30 at locations upstream of branches of the filling line 30 connected to the fuel tanks 60. The high-pressure sensor 42 is mounted at a location upstream of the pressure reducing valve 54 and downstream of the location where lines connected to the fuel tanks 60 flow into the single supply line 32.

[0079] For example, when the configuration in which the fuel cell system 25 includes a plurality of fuel tanks 60 is applied to the fourth embodiment, the temperature sensor 45 may be provided for each of the fuel tanks 60, and the temperature increase rate ΔTx may be monitored using the average of the detection values ​​of all the temperature sensors 45. Alternatively, the temperature increase rate ΔTx may be monitored using the detection value of the temperature sensor 45 for a specific one of the fuel tanks 60. It is only necessary to obtain in advance the relationship between the detection value of the temperature sensor 45 used and the pressure loss during filling, and to determine the reference rate ΔTxa based on the obtained relationship.

[0080] (F2) The pressure loss during filling can be estimated by a method different from the second to fifth embodiments. Any physical quantity that changes during the filling of the fuel tank 60 with hydrogen and that is a parameter having a specific relationship with the pressure loss can be used in a manner similar to the filling flow rate F, the pressure increase rate ΔPi, and the temperature increase rate ΔTx. For example, the time elapsed from the start of filling can be used in the case where filling conditions are determined in advance.

[0081] (F3) In the second to fifth embodiments, the reference flow rate Fa is used for the filling flow rate F ( Fig. 4), the reference rate ΔPia for the pressure increase rate ΔPi ( Fig. 7) and the reference rate ΔTxa for the temperature increase rate ΔTx ( Fig.10) is determined based on the relationship with the pressure loss to determine when to start the abnormality detection control. However, the present disclosure may have a different configuration. The timing at which the measurement accuracy of the tank pressure by the filling pressure sensor 41 is sufficiently increased only needs to be determined to start the abnormality detection control. The relationship between the pressure loss and the filling flow rate F, the pressure increase rate ΔPi, and the temperature increase rate ΔTx does not necessarily need to be obtained in advance to determine the reference used for the determination.

[0082] The present disclosure is not limited to the above embodiments and can be implemented with various configurations without departing from the spirit and scope of the present disclosure. For example, those technical features in the embodiments that correspond to the technical features in each form described in the "Summary of the Invention" section can be appropriately replaced or combined to solve some or all of the problems described above or to achieve some or all of the effects described above. Those technical features that are not described as essential in the specification may be omitted as appropriate.

Claims

[1] Fuel cell system, comprising: a fuel cell (66); a fuel tank (60) which stores fuel gas to be supplied to the fuel cell (66); a filling flow path (30) through which the fuel gas to be supplied to the fuel tank (60) flows; a supply flow path (32) connecting the fuel cell (66) and the fuel tank (60); a first pressure sensor (41) mounted on the filling flow path (30) and detecting a pressure in the filling flow path (30); a second pressure sensor (42) mounted on the supply flow path (32) and detecting a pressure of the fuel gas at an outlet of the fuel tank (60); a temperature sensor (45) which detects a temperature in the fuel tank (60); and a control unit (68) configured to perform anomaly detection control for the first pressure sensor (41) and the second pressure sensor (42), wherein the control unit (68) is configured such that, in the anomaly detection control obtains a maximum filling pressure from a detection value of the first pressure sensor (41), the maximum filling pressure corresponding to the pressure in the filling flow path (30) at a maximum pressure time when the pressure in the filling flow path (30) becomes maximum during filling of the fuel tank (60) with the fuel gas; determines that both the first pressure sensor (41) and the second pressure sensor (42) are normal when a first difference is equal to or less than a predetermined first reference value, or when a second difference is equal to or less than a predetermined second reference value, wherein the first difference corresponds to a difference between a supply start pressure and the maximum filling pressure, wherein the supply start pressure corresponds to a detection value of the second pressure sensor (42) at the start of supplying the fuel gas to the fuel cell (66) when the supply of the fuel gas from the fuel tank (60) to the fuel cell (66) is started for the first time after the filling of the fuel tank (60) with the fuel gas is completed, and wherein the second difference corresponds to a difference between an amount of the fuel gas in the fuel tank (60) at the start of supplying the fuel gas to the fuel cell (66),which is calculated using the temperature detected by the temperature sensor (45) at the start of supply of the fuel gas to the fuel cell (66) and the supply start pressure, and corresponds to an amount of the fuel gas in the fuel tank (60) at the maximum pressure time, which is calculated using the temperature detected by the temperature sensor (45) at the maximum pressure time and the maximum filling pressure; and, determines that there is a possibility that the first pressure sensor (41) and / or the second pressure sensor (42) is / are abnormal when the first difference is greater than the predetermined first reference value or when the second difference is greater than the predetermined second reference value, and wherein the fuel cell system further comprises: a flow rate sensor which detects a flow rate of the fuel gas flowing through the filling flow path (30), wherein the control unit (68) is configured to start the abnormality detection control when the flow rate detected by the flow rate sensor becomes equal to or lower than a predetermined reference flow rate after the fuel tank (60) starts filling with the fuel gas. [2] The fuel cell system according to claim 1, wherein the reference flow rate is 30 g / sec. [3] Fuel cell system, comprising: a fuel cell (66); a fuel tank (60) which stores fuel gas to be supplied to the fuel cell (66); a filling flow path (30) through which the fuel gas to be supplied to the fuel tank (60) flows; a supply flow path (32) connecting the fuel cell (66) and the fuel tank (60); a first pressure sensor (41) mounted on the filling flow path (30) and detecting a pressure in the filling flow path (30); a second pressure sensor (42) mounted on the supply flow path (32) and detecting a pressure of the fuel gas at an outlet of the fuel tank (60); a temperature sensor (45) which detects a temperature in the fuel tank (60); and a control unit (68) configured to perform anomaly detection control for the first pressure sensor (41) and the second pressure sensor (42), wherein the control unit (68) is configured such that, in the anomaly detection control obtains a maximum filling pressure from a detection value of the first pressure sensor (41), the maximum filling pressure corresponding to the pressure in the filling flow path (30) at a maximum pressure time when the pressure in the filling flow path (30) becomes maximum during filling of the fuel tank (60) with the fuel gas; determines that both the first pressure sensor (41) and the second pressure sensor (42) are normal when a first difference is equal to or less than a predetermined first reference value, or when a second difference is equal to or less than a predetermined second reference value, wherein the first difference corresponds to a difference between a supply start pressure and the maximum filling pressure, wherein the supply start pressure corresponds to a detection value of the second pressure sensor (42) at the start of supplying the fuel gas to the fuel cell (66) when the supply of the fuel gas from the fuel tank (60) to the fuel cell (66) is started for the first time after the filling of the fuel tank (60) with the fuel gas is completed, and wherein the second difference corresponds to a difference between an amount of the fuel gas in the fuel tank (60) at the start of supplying the fuel gas to the fuel cell (66),which is calculated using the temperature detected by the temperature sensor (45) at the start of supply of the fuel gas to the fuel cell (66) and the supply start pressure, and corresponds to an amount of the fuel gas in the fuel tank (60) at the maximum pressure time, which is calculated using the temperature detected by the temperature sensor (45) at the maximum pressure time and the maximum filling pressure; and, determines that there is a possibility that the first pressure sensor (41) and / or the second pressure sensor (42) is / are abnormal when the first difference is greater than the predetermined first reference value or when the second difference is greater than the predetermined second reference value, and wherein the control unit (68) is configured to: obtains a pressure increase rate of the filling flow path (30) during filling of the fuel tank (60) with the fuel gas using the detection value of the first pressure sensor (41); and the anomaly detection control starts as soon as the pressure increase rate after the start of filling the fuel tank (60) with the fuel gas becomes equal to or lower than a predetermined first reference rate. [4] The fuel cell system according to claim 3, wherein the predetermined first reference rate is 23 MPa / min. [5] Fuel cell system, comprising: a fuel cell (66); a fuel tank (60) which stores fuel gas to be supplied to the fuel cell (66); a filling flow path (30) through which the fuel gas to be supplied to the fuel tank (60) flows; a supply flow path (32) connecting the fuel cell (66) and the fuel tank (60); a first pressure sensor (41) mounted on the filling flow path (30) and detecting a pressure in the filling flow path (30); a second pressure sensor (42) mounted on the supply flow path (32) and detecting a pressure of the fuel gas at an outlet of the fuel tank (60); a temperature sensor (45) which detects a temperature in the fuel tank (60); and a control unit (68) configured to perform anomaly detection control for the first pressure sensor (41) and the second pressure sensor (42), wherein the control unit (68) is configured such that, in the anomaly detection control obtains a maximum filling pressure from a detection value of the first pressure sensor (41), the maximum filling pressure corresponding to the pressure in the filling flow path (30) at a maximum pressure time when the pressure in the filling flow path (30) becomes maximum during filling of the fuel tank (60) with the fuel gas; determines that both the first pressure sensor (41) and the second pressure sensor (42) are normal when a first difference is equal to or less than a predetermined first reference value, or when a second difference is equal to or less than a predetermined second reference value, wherein the first difference corresponds to a difference between a supply start pressure and the maximum filling pressure, wherein the supply start pressure corresponds to a detection value of the second pressure sensor (42) at the start of supplying the fuel gas to the fuel cell (66) when the supply of the fuel gas from the fuel tank (60) to the fuel cell (66) is started for the first time after the filling of the fuel tank (60) with the fuel gas is completed, and wherein the second difference corresponds to a difference between an amount of the fuel gas in the fuel tank (60) at the start of supplying the fuel gas to the fuel cell (66),which is calculated using the temperature detected by the temperature sensor (45) at the start of supply of the fuel gas to the fuel cell (66) and the supply start pressure, and corresponds to an amount of the fuel gas in the fuel tank (60) at the maximum pressure time, which is calculated using the temperature detected by the temperature sensor (45) at the maximum pressure time and the maximum filling pressure; and, determines that there is a possibility that the first pressure sensor (41) and / or the second pressure sensor (42) is / are abnormal when the first difference is greater than the predetermined first reference value or when the second difference is greater than the predetermined second reference value, and wherein the control unit (68) is configured to: obtains a temperature increase rate of the fuel tank (60) during filling of the fuel tank (60) with the fuel gas using the temperature detected by the temperature sensor (45); and the anomaly detection control starts after the temperature increase rate after the start of filling the fuel tank (60) with the fuel gas becomes equal to or lower than a predetermined second reference rate. [6] The fuel cell system according to claim 5, wherein the predetermined second reference rate is 20°C / min. [7] Method for detecting an abnormality of a fuel cell system, wherein the fuel cell system comprises a fuel cell (66); a fuel tank (60) which stores fuel gas to be supplied to the fuel cell (66); a filling flow path (30) through which the fuel gas to be supplied to the fuel tank (60) flows; a supply flow path (32) connecting the fuel cell (66) and the fuel tank (60); a first pressure sensor (41) mounted on the filling flow path (30) and detecting a pressure in the filling flow path (30); and a second pressure sensor (42) mounted on the supply flow path (32) and detecting a pressure of the fuel gas at an outlet of the fuel tank (60), the method comprising: Obtaining a maximum filling pressure from a detection value of the first pressure sensor (41), the maximum filling pressure corresponding to the pressure in the filling flow path (30) at a maximum pressure time when the pressure in the filling flow path (30) becomes maximum during filling of the fuel tank (60) with the fuel gas; Determining that both the first pressure sensor (41) and the second pressure sensor (42) are normal when a first difference is equal to or less than a predetermined first reference value, or when a second difference is equal to or less than a predetermined second reference value, wherein the first difference corresponds to a difference between a supply start pressure and the maximum filling pressure, wherein the supply start pressure corresponds to a detection value of the second pressure sensor (42) at the start of the supply of the fuel gas to the fuel cell (66) when the supply of the fuel gas from the fuel tank (60) to the fuel cell (66) is started for the first time after the filling of the fuel tank (60) with the fuel gas is completed, and wherein the second difference corresponds to a difference between an amount of the fuel gas in the fuel tank (60) at the start of the supply of the fuel gas to the fuel cell (66),which is calculated using a temperature in the fuel tank (60) at the start of supplying the fuel gas to the fuel cell (66) and the supply start pressure, and an amount of the fuel gas in the fuel tank (60) at the maximum pressure time, which is calculated using a temperature in the fuel tank (60) at the maximum pressure time and the maximum filling pressure; and, Determining that there is a possibility that the first pressure sensor (41) and / or the second pressure sensor (42) is abnormal when the first difference is greater than the predetermined first reference value or when the second difference is greater than the predetermined second reference value, wherein the fuel cell system further comprises: a flow rate sensor which detects a flow rate of the fuel gas flowing through the filling flow path (30), and wherein the method is started as soon as the flow rate detected by the flow rate sensor becomes equal to or lower than a predetermined reference flow rate after a start of filling the fuel tank (60) with the fuel gas.

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