Fuel cell system

Abstract

Fuel cell system (10) with: a fuel cell (15); an anode gas supply system (50A) configured to supply anode gas to the fuel cell (15), wherein the anode gas supply system (50A) includes an anode gas supply passage (501) through which the anode gas flows towards the fuel cell (15); an anode gas circulation system (50B) configured to circulate anode exhaust gas discharged from the fuel cell (15) to the anode gas supply passage (501), wherein the anode gas circulation system (50B) an anode gas circulation passage (502) through which the anode exhaust gas flows towards the anode gas supply passage (501), and a gas-liquid separator (57) which is provided in the anode gas circulation passage (502) and is configured to separate liquid water from the anode exhaust gas; a cathode gas supply and delivery system (30) which a cathode gas supply passage (302) configured to supply cathode gas to the fuel cell (15), and includes a cathode gas discharge passage (308) through which cathode gas discharged from the fuel cell (15) is discharged to an outside of the fuel cell system (10); a gas-liquid discharge passage (504) which is connected to the gas-liquid separator (57); a gas-liquid dispensing valve (58) provided in the gas-liquid dispensing passage (504) and configured to open and close the gas-liquid dispensing passage (504); a flow rate acquisition section (66) configured to acquire a discharge gas flow rate of the anode exhaust gas discharged from the gas-liquid discharge valve (58); and a control section (62) configured to perform an operating determination process which includes a normal / deviation determination of whether the gas-liquid dispensing valve (58) is normally open or not, wherein the control section (62), after instructing the gas-liquid dispensing valve (58) to be open, performs the normal / deviation determination such that The control section (62) determines that the gas-liquid discharge valve (58) is normally open when the discharge gas flow rate of the anode exhaust gas is a predetermined normal reference value or higher, and The control section (62) determines that the gas-liquid discharge valve (58) is not normally open when the discharge gas flow rate of the anode exhaust is less than the predetermined normal reference value, characterized by a water storage quantity acquisition section (67) configured to acquire a quantity of the liquid water accumulated in the gas-liquid separator (57), wherein: the control section (62) in a normal operating state of the fuel cell system (10), in which the gas-liquid discharge valve (58) is normally open, in a case where the amount of liquid water accumulated in the gas-liquid separator (57) is a predetermined initial liquid water quantity or more, performs a normal gas discharge operation by controlling the anode gas supply system (50A) to supply the anode gas to the fuel cell (15) and instructing the gas-liquid discharge valve (58) to be open; and a pressure of the anode gas to be supplied to the fuel cell (15) during the operating determination process is higher than a pressure of the anode gas to be supplied to the fuel cell (15) during the normal gas delivery process.

Description

Background of the invention 1. Field of the invention

[0001] The invention relates to a fuel cell system technology. 2. Description of the state of the art

[0002] From JP 2008 - 59 974 A, JP 2011 - 3 465 A and DE 10 2015 119 520 A1, a technology is known in which a gas-liquid discharge valve is placed in a fuel cell system and the gas-liquid discharge valve is configured to discharge to the outside an impurity gas, such as nitrogen gas, contained in the anode exhaust gas discharged from a fuel cell, and liquid water produced by the fuel cell's power generation. DE 10 2015 119 520 A1 discloses a fuel cell system with the features of the preamble of claim 1. Brief description of the invention

[0003] In the prior art, if the temperature of the gas-liquid dispensing valve is at or above the defrosting temperature, it is determined that the gas-liquid dispensing valve can be opened normally. However, even when the temperature of the gas-liquid dispensing valve is at or above the defrosting temperature, in some cases the gas-liquid dispensing valve cannot be opened normally. For example, if foreign matter such as dust is trapped in the gas-liquid dispensing valve, a normal valve opening state may not be achieved in some cases, even if the temperature of the gas-liquid dispensing valve is at or above the defrosting temperature. Similarly, if the foreign matter is, for example, ice, the ice will not melt completely even if the temperature of the gas-liquid dispensing valve is at or above the defrosting temperature, so a normal valve opening process cannot be carried out.Accordingly, the determination based on the temperature of the gas-liquid dispensing valve has the problem that the determination of whether the gas-liquid dispensing valve is normally open or not cannot be carried out accurately.

[0004] The invention can be achieved with the following embodiments.

[0005] One embodiment of the invention provides for a fuel cell system with the features of claim 1.

[0006] If the normal / deviation determination is performed using the discharge gas flow rate at the gas-liquid discharge valve in this configuration, it is possible to accurately determine whether the gas-liquid discharge valve is normally open. For example, it is possible to accurately determine a case in which the gas-liquid discharge valve is not operating normally for a reason other than freezing. If the normal / deviation determination is performed using the discharge gas flow rate, it is also possible to accurately determine the normal / deviation status even if the gas-liquid discharge valve is not normally open due to freezing. Furthermore, since the pressure of the supplied anode gas is higher in this configuration, the discharge gas flow rate of the anode exhaust gas is also higher. Accordingly, it is possible to shorten the time required for the normal / deviation determination.

[0007] In the above configuration, the fuel cell system can also include a temperature acquisition section configured to acquire an ambient temperature for the fuel cell system. In a case where the control section receives an activation instruction to turn on the fuel cell system, it can perform a subfreezing start-up if the ambient temperature is freezing or below. This is achieved by controlling the anode gas supply system to deliver anode gas to the fuel cell and instructing the gas-liquid discharge valve to be open. After instructing the gas-liquid discharge valve to be open in the subfreezing start-up, the control section can perform the normal / deviation determination.

[0008] With this design, the normal / deviation determination can be carried out by using the start-up process beginning below the freezing point.

[0009] In the above configuration, the cathode gas supply / discharge system can also include a compressor located in the cathode gas supply passage. The gas-liquid discharge passage can be connected to the cathode gas discharge passage. The control section can regulate the operation of the compressor such that the flow rate of the cathode gas flowing through the cathode gas discharge passage during the operational determination process is greater than the flow rate of the cathode gas flowing through the cathode gas discharge passage during normal gas discharge.

[0010] With this design, the anode exhaust gas can be safely diluted by the cathode gas even in cases where the amount of anode exhaust gas to be discharged from the gas-liquid delivery valve increases.

[0011] After the control section, in the configuration described above, has determined during the operating procedure that the gas-liquid discharge valve is not open normally, it can initiate a warm-up operation to raise the temperature of the fuel cell. The control section can perform a restoration determination, at least during or after the warm-up operation, to ascertain whether the gas-liquid discharge valve has returned to normal operation.After the control section has instructed the gas-liquid discharge valve to be open, the recovery determination can be carried out such that the control section can determine that the operation of the gas-liquid discharge valve is restored to normal if the discharge gas flow rate of the anode exhaust is a predetermined recovery reference value or higher, and that the control section can determine that the operation of the gas-liquid discharge valve is not restored to normal if the discharge gas flow rate of the anode exhaust is lower than the predetermined recovery reference value.

[0012] In this configuration, if the fuel cell temperature is increased during the warm-up phase, the gas-liquid dispensing valve can be heated using heat from the fuel cell. This allows the valve to thaw if it malfunctions due to freezing, restoring normal operation. The restoration process also verifies whether the valve's operation has been successfully restored.

[0013] In the above configuration, the control section, in a pre-recovery state of the fuel cell system before the operation of the gas-liquid discharge valve has returned to normal, can execute a recovery gas discharge operation by instructing the gas-liquid discharge valve to be open when the amount of liquid water accumulated in the gas-liquid separator reaches at least a second quantity of liquid water that is smaller than the first quantity of liquid water. The control section can execute the recovery determination after it has instructed the gas-liquid discharge valve to be open during the recovery gas discharge operation.

[0014] In this configuration, if the liquid water reaches at least the second liquid water quantity, which is smaller than the first, the control section executes the gas-liquid restoration process. This allows the number of execution times of the gas-liquid restoration process to be increased, thereby increasing the number of command times to instruct the gas-liquid dispensing valve to be open. Accordingly, it is possible to increase the frequency of the restoration command, thus preventing a delay in the subsequent restoration process.

[0015] In the above configuration, the fuel cell system may also include a pressure sensor configured to measure pressure within the anode gas supply passage. The flow rate acquisition section can calculate the discharge gas flow rate of the anode exhaust by using a change in the pressure measured by the pressure sensor. In a case where the recovery determination is performed, the control section may perform at least one of the following operations: a first pre-operation in which the pressure of the anode gas to be supplied to the fuel cell is increased so that it is higher than the pressure of the anode gas to be supplied to the fuel cell during the execution of the normal gas discharge operation;a second preliminary step in which the flow rate of the anode exhaust gas to be circulated from the anode gas circulation port to the anode gas supply port is reduced so that it is lower than the flow rate of the anode exhaust gas to be circulated from the anode gas circulation port to the anode gas supply port during the execution of the normal gas delivery process; and a third preliminary step in which the current value of the fuel cell is reduced so that it is lower than the current value of the fuel cell during the execution of the normal gas delivery process.

[0016] If at least one of the first to the third preliminary steps is executed with this configuration, the probability that the pressure measured by the pressure sensor will change due to a factor other than the anode exhaust gas being discharged from the gas-liquid discharge valve can be reduced. This can further improve the accuracy of calculating the discharge gas flow rate, making it possible to perform the recovery determination more accurately.

[0017] In the above configuration, the cathode gas supply / discharge system can include a compressor configured to direct the cathode gas towards the cathode gas discharge port. The gas-liquid discharge port can be connected to the cathode gas discharge port. The control section can operate the compressor such that the cathode gas flow rate through the cathode gas discharge port at the time the recovery process is performed is greater than the cathode gas flow rate through the cathode gas discharge port during normal gas discharge operation.

[0018] With this design, the anode exhaust gas can be safely diluted by the cathode gas even in cases where the amount of anode exhaust gas to be discharged from the gas-liquid delivery valve increases.

[0019] In the above configuration, the control section can determine that the gas-liquid discharge valve is normally open in a case where the accumulation quantity of anode exhaust gas discharged from the gas-liquid discharge passage within a predetermined time period is a predetermined reference accumulation quantity or more, after the control section has instructed the gas-liquid discharge valve to be open, after the control section has determined during the normal / deviation determination that the gas-liquid discharge valve is not normally open, but before the recovery determination is executed, even if the discharge gas flow rate of the anode exhaust gas is less than the normal reference value.

[0020] With this design, the determination of whether the gas-liquid discharge valve is normally open or not is carried out using two methods: one method that uses the discharge gas flow rate of the anode exhaust gas, and one method that uses the gas discharge quantity of the anode exhaust gas. This makes it possible to determine more accurately whether the gas-liquid discharge valve is normally open.

[0021] The invention can be implemented in various other forms besides the embodiments described above. For example, the invention can be implemented in forms such as a control method for a fuel cell system and a vehicle containing a fuel cell system. Brief description of the drawings

[0022] With reference to the accompanying drawings, in which identical numbers denote identical elements, the features, advantages, and technical and industrial significance of exemplary embodiments of the invention are now described. The drawings show: Fig. 1 an explanatory view showing the outline drawing of a fuel cell system in a first embodiment; Fig. 2 a schematic diagram illustrating the electrical structure of the fuel cell system; Fig. 3 a flowchart that includes an operational determination process of a gas-liquid dispensing valve; Fig. 4. A flowchart of a starting process beginning below freezing; Fig. 5 a curve diagram representing a characteristic curve in an open state of the gas-liquid dispensing valve; Fig. 6. A timeline of various processes, including the operational determination process, that are carried out by a control section; Fig. 7 a further flowchart that is executed by the control device of the fuel cell system according to a second embodiment; Fig. 8 another flowchart that is executed by the control device of the fuel cell system according to a third embodiment; Fig. 9 a timeline of step S130, step S140 and step S160, which is in Fig. 8 are shown; Fig. 10 a flowchart of a deviation presence determination in a fourth embodiment; and Fig. 11 a view to describe a predetermined reference collection set. Detailed description of embodiments A. First embodiment

[0023] Fig. Figure 1 is an explanatory view showing the outline of a fuel cell system 10 according to a first embodiment. The fuel cell system 10 of this embodiment is, for example, provided in a fuel cell vehicle 12 and is used as a power generator configured to drive a drive motor for the fuel cell vehicle 12. The fuel cell system 10 comprises a fuel cell 15, a cathode gas supply / discharge system 30, an anode gas supply / discharge system 50, a coolant circulation system 70, and a control device 60.

[0024] The control device 60 comprises a control section 62 and a memory section 64. The control section 62 controls the operation of the fuel cell system 10 by executing various programs stored in the memory section 64. For example, the control section 62 performs an operating determination process that includes a normal / deviation determination of whether the operation of a (later described) gas-liquid dispensing valve 58 is normal or not. In addition to the various programs, the memory section 64 stores various threshold values ​​that are used for the operating determination process and the like.

[0025] Fuel cell 15 is a solid polymer fuel cell configured to generate electricity through an electrochemical reaction of oxygen and hydrogen upon receiving a supply of cathode gas and anode gas as reactant gases. In this embodiment, the cathode gas is air and the anode gas is hydrogen gas. Fuel cell 15 has a stacked structure in which a plurality of individual cells are stacked on top of each other. Each individual cell is a power-generating element capable of generating electricity itself. The individual cell contains a membrane electrode assembly and two separators between which the membrane electrode assembly is clamped. The membrane electrode assembly comprises an electrolyte membrane, an anode arranged on a first surface of the electrolyte membrane, and a cathode arranged on a second surface of the electrolyte membrane.The electrolyte membrane is a solid polymer thin film that exhibits excellent proton conductivity in a wet state, where water is present in the electrolyte membrane. An outer circumferential end of the individual cell is provided with (not shown) distributors for the reactant gases, the distributors extending in the stacking direction of the individual cells and branching to connect to a power-generating section of the individual cell. The individual cells are fixed in a stacked state, clamped in the stacking direction.

[0026] The cathode gas supply and discharge system 30 supplies the fuel cell 15 with cathode gas and discharges the cathode gas to the outside. The cathode gas supply and discharge system 30 comprises a cathode gas supply system 30A and a cathode gas discharge system 30B. The cathode gas supply system 30A supplies the fuel cell 15 with cathode gas. The cathode gas supply system 30A includes a cathode gas supply passage 302, an air filter 31, a compressor 33, a motor 34, an intercooler 35, and a flow divider valve 36.

[0027] The cathode gas supply passage 302 is located upstream of the fuel cell 15 and is a pipe through which the outside of the fuel cell system 10 communicates with the cathode of the fuel cell 15. The air filter 31 is located upstream of the compressor 33 in the cathode gas supply passage 302 and is configured to remove foreign matter from the cathode gas supplied to the fuel cell 15. The compressor 33 is located in the cathode gas supply passage 302, which is located upstream of the fuel cell 15, and is configured to discharge compressed air to the cathode in response to a command from the control section 62. The compressor 33 is driven by the motor 34, which operates in response to a command from the control section 62.The intercooler 35 is located downstream of the compressor 33 in the cathode gas supply passage 302. The intercooler 35 cools the cathode gas, which is compressed by the compressor 33 and reaches a high temperature. The flow divider valve 36, for example, is a three-way valve and is configured such that, by setting an opening degree of the flow divider valve 36, a flow rate of the cathode gas flowing from the cathode gas supply passage 302 towards the fuel cell 15 and a flow rate of the cathode gas flowing through a bypass passage 306, which branches off from the cathode gas supply passage 302 and bypasses the fuel cell 15, are set. The bypass passage 306 is connected to a (later described) cathode gas discharge passage 308. The cathode gas flowing through the bypass passage 306 is discharged to the outside via the cathode gas discharge passage 308.

[0028] The cathode gas delivery system 30B discharges the cathode gas to the outside. The cathode gas delivery system 30B includes the cathode gas delivery passage 308, the bypass passage 306, and a pressure control valve 37. The cathode gas delivery passage 308 is a tube through which cathode gas (hereinafter also referred to as "cathode exhaust") discharged from the fuel cell 15 and the cathode gas flowing through the bypass passage 306 are discharged to the outside. The pressure control valve 37 adjusts its opening degree to set a back pressure on a cathode-side passage of the fuel cell 15. The pressure control valve 37 is located upstream of a point in the cathode gas delivery passage 308 to which the bypass passage 306 is connected. A silencer 310 is placed in a downstream end of the cathode gas discharge passage 308.

[0029] The anode gas supply and delivery system comprises an anode gas supply system 50A, an anode gas circulation system 50B, and an anode gas delivery system 50C.

[0030] The anode gas supply system 50A supplies the anode gas to the fuel cell 15. The anode gas supply system 50A includes an anode gas tank 51, an anode gas supply port 501, an on / off valve 52, a regulator 53, an injector 54, and a pressure sensor 59. For example, high-pressure hydrogen gas is stored in the anode gas tank 51. The anode gas supply port 501 is connected to the anode gas tank 51 and the fuel cell 15 and is a pipe through which the anode gas, which is sent from the anode gas tank 51, flows into the fuel cell 15. When the on / off valve 52 is in an open position, the anode gas in the anode gas tank 51 flows downstream. The regulator 53 sets a pressure of the anode gas on the upstream side of the injector 54 based on control by the control section 62.Injector 54 is located upstream of an anode gas supply passage from a branch point with an anode gas circulation passage 502 (described later). Injector 54 is an on / off valve that is electromagnetically actuated according to a control duration or valve opening time set by the control section 62 and is configured to set an anode gas supply quantity to be supplied to the fuel cell 15. Pressure sensor 59 measures an internal pressure (supply pressure of the anode gas) in the anode gas supply passage 501 downstream of injector 54. The measurement result is transmitted to the control device 60.

[0031] The anode gas circulation system 50B recirculates the anode gas (also referred to as "anode exhaust") emitted from the fuel cell 15 back to the anode gas supply port 501. The anode gas circulation system 50B comprises the anode gas circulation port 502, a gas-liquid separator 57, a circulation pump 55, and a motor 56. The anode gas circulation port 502 is connected to the fuel cell 15 and the anode gas supply port 501 and is a pipe through which the anode exhaust gas, which is sent to the anode gas supply port 501, flows. The gas-liquid separator 57 is located in the anode gas circulation passage 502 and is configured to separate liquid water from the anode exhaust gas in which the liquid water is mixed. The circulation pump 55 drives the motor 56 to circulate the anode exhaust gas in the anode gas circulation passage 502 towards the anode gas supply passage 501.

[0032] The anode gas discharge system 50C discharges the anode exhaust gas or the liquid water produced by the fuel cell 15 during power generation to the outside. The anode gas discharge system 50C includes a gas-liquid discharge passage 504 and the gas-liquid discharge valve 58. The gas-liquid discharge passage 504 is a tube through which a discharge port of the gas-liquid separator 57, from which the liquid water is discharged, communicates with the outside.

[0033] The gas-liquid discharge valve 58 is located in the gas-liquid discharge passage 504 and is configured to open and close the gas-liquid discharge passage 504. For example, a diaphragm valve is used as the gas-liquid discharge valve 58. In a normal operating state of the fuel cell system 10, where the gas-liquid discharge valve 58 is determined to be normally open, the control section 62 instructs the gas-liquid discharge valve 58 to be open at a predetermined time and controls the injector 54 to open and close, thus supplying the anode gas to the downstream side (normal gas discharge operation). In this process, the gas-liquid discharge valve 58 assumes an open state, so that nitrogen gas, which is an impurity gas contained in the anode exhaust gas, and the liquid water are discharged to the outside via the gas-liquid discharge passage 504.The predetermined time is the point in time when the liquid water in the gas-liquid separator 57 has accumulated, for example, a predetermined initial quantity of liquid water or more. It should be noted that the circulation pump 55 can be driven or stopped during the normal gas discharge process.

[0034] The coolant circulation system 70 regulates the temperature of the fuel cell 15 by using a coolant. Water or an antifreeze solution such as ethylene glycol is used as the coolant. The coolant circulation system 70 includes a coolant circulation passage 79, a coolant circulation pump 74, a motor 75, a radiator 72, a radiator fan 71, and a temperature sensor 73.

[0035] The coolant circulation system 79 comprises a coolant supply port 79A and a coolant discharge port 79B. The coolant supply port 79A is a pipe through which the coolant is supplied to the fuel cell 15. The coolant discharge port 79B is a pipe through which the coolant is discharged from the fuel cell 15. The coolant circulation pump 74 sends the coolant in the coolant supply port 79A through the drive of the motor 75 to the fuel cell 15. The radiator 72 cools the flowing coolant by dissipating heat through airflow supplied by the radiator fan 71. The temperature sensor 73 measures the temperature of the coolant in the coolant discharge port 79B. The measured coolant temperature is transmitted to the control section 62.

[0036] The control section 62 comprises a flow rate acquisition section 66 and a water storage quantity acquisition section 67, which operate by executing programs stored in the memory section 64. The flow rate acquisition section 66 acquires a discharge gas flow rate of the anode exhaust gas discharged from the gas-liquid discharge valve 58 by using a change in pressure acquired from the pressure sensor 59. A calculation method for the discharge gas flow rate is described later. The water storage quantity acquisition section 67 acquires a quantity of liquid water accumulated in the gas-liquid separator 57.In this embodiment, the water storage quantity acquisition section 67 can estimate the quantity of liquid water produced by the fuel cell 15 and the calculated quantity of liquid water as a water storage quantity by using the power generation quantity of the fuel cell 15. Furthermore, in another embodiment, at least one water level sensor can be placed in the gas-liquid separator 57, so that the water storage quantity is acquired based on a detection signal from the water level sensor. The water level sensor is positioned, for example, according to a threshold value of the water storage quantity, which is to be used for control by the control section 62.In a case where the normal gas release process is carried out, for example, at the time when the water storage quantity is the first quantity of liquid water or more, the water level sensor is placed at a location corresponding to the first quantity of liquid water.

[0037] Fig. Figure 2 is a schematic diagram illustrating the electrical setup of the fuel cell system 10. The fuel cell system 10 includes an FDC 95, a DC-AC converter 98, a cell voltmeter 91, and a current sensor 92.

[0038] The cell voltmeter 91 is connected to all individual cells 151 of the fuel cell 15 and measures the respective cell voltages of all individual cells 151. The cell voltmeter 91 transmits the measurement results to the control device 60. The current sensor 92 measures a value of an output current from the fuel cell 15 and transmits it to the control device 60.

[0039] The FDC 95 is a circuit configured as a DC-DC converter. Based on a voltage command value transmitted by the control device 60, the FDC 95 controls an output voltage. It also controls an output current from the fuel cell 15 based on a current command value transmitted by the control device 60. The current command value serves as a setpoint for the output current from the fuel cell 15 and is set by the control device 60. The control device 60 generates the current command value, for example, by calculating a required current value for the fuel cell 15.

[0040] The DC-AC converter 98 is connected to the fuel cell 15 and a load 255. The DC-AC converter 98 converts the DC power output by the fuel cell 15 into AC power and supplies it to the load 255.

[0041] The fuel cell system 10 also includes a secondary battery 96 and a BDC 97. The secondary battery 96 is, for example, a nickel-metal hydride battery or a lithium-ion battery and functions as an emergency power supply. The secondary battery 96 also supplies electrical current to the fuel cell 15 and charges it with current generated by the fuel cell 15 or with renewable energy.

[0042] The BDC 97 is a circuit configured similarly to the FDC 95 as a DC-DC converter. Responding to a command from the control device 60, it acts as a control section, regulating the charging and discharging of the secondary battery 96. The BDC 97 measures the state of charge (SOC) and transmits it to the control device 60.

[0043] Fig. Figure 3 is a flowchart that includes the operating determination process for the gas-liquid dispensing valve 58. Fig. Figure 4 is a flowchart of a start-up process beginning below freezing. Fig. Figure 5 is a curve representing a characteristic curve in the open state of the gas-liquid dispensing valve 58. The curve of Fig. 5 The vertical axis indicates a gas discharge quantity of the anode exhaust gas released by the gas-liquid discharge valve 58, and the horizontal axis indicates an elapsed time. The in Fig. The operating determination process shown in Figure 3 is executed at a commissioning point when a start switch of the fuel cell vehicle 12 is turned on and the fuel cell system 10 receives an activation instruction. The operating determination process can also be executed at a predetermined time after the commissioning point.

[0044] As in Fig. As shown in Figure 3, the control section 62 determines whether an ambient temperature, which is the temperature of an environment in which the fuel cell system 10 is located, is at or below freezing (step S10). In this embodiment, the ambient temperature is a coolant temperature in the coolant discharge passage 79B, which is measured by the temperature sensor 73 ( Fig. 1) is acquired, which is a temperature acquisition section. It should be noted that in other embodiments, the ambient temperature can be an outside temperature or a temperature of the gas-liquid dispensing valve 58. The outside temperature can be acquired, for example, by placing an outside temperature sensor. The temperature of the gas-liquid dispensing valve 58 can be acquired, for example, by placing a temperature sensor in the gas-liquid dispensing valve 58.

[0045] If control section 62 determines "No" in step S10, it notifies the driver that the vehicle is authorized to drive (step S50). In step S50, the information that the fuel cell vehicle 12 is in a ready-to-drive state is displayed on an on-board monitor or similar device, thus notifying the driver that the vehicle is authorized to drive. However, if control section 62 determines "Yes" in step S10, it executes a sub-freezing start-up procedure (step S15). The sub-freezing start-up procedure is a process that ensures a required amount of electricity generation from the fuel cell 15 even if the fuel cell 15 freezes.

[0046] As in Fig. As shown in Figure 4, during the sub-freezing start-up process, the control section 62 drives the compressor 33 (step S70). Subsequently, the control section 62 controls the opening and closing of the injector 54 to supply the anode gas to the fuel cell 15 (step S72). While the anode gas is being supplied to the fuel cell 15 in step S72, the circulation pump 55 stops, allowing the anode gas to fill the interior of the fuel cell 15's anode. The control section 62 also instructs the gas-liquid discharge valve 58 to be open (step S74). The sub-freezing start-up process continues until the supply of anode gas to the fuel cell 15's anode reaches or exceeds the anode's capacity, the supply quantity being calculated using a pressure value measured by the pressure sensor 59.

[0047] When, during the start-up process which begins below freezing, the gas-liquid discharge valve 58 is instructed to be open, the control section 62 determines whether the discharge gas flow rate of the anode exhaust from the gas-liquid discharge valve 58 is a predetermined normal reference value or not (step S30 in Fig. 3) In step S30, the discharge gas flow rate of the anode exhaust and the predetermined normal reference value can both be expressed as mass flows and compared with each other, or both can be expressed as volume flows and compared with each other.

[0048] The normal reference value is stored in memory section 64. As in Fig. As shown in 5, the normal reference value Ls [m 3 / s] set so that it is a value smaller than a construction value Lc [m 3The design value Lc is the discharge gas flow rate at the time when the gas-liquid discharge valve 58 is in an open state. The design value Lc is a value achieved when the valve opening rate of the gas-liquid discharge valve 58 is 100%. The valve opening rate is a percentage (%) of the actual flow cross-sectional area of ​​the gas-liquid discharge valve 58 relative to the flow cross-sectional area of ​​the gas-liquid discharge valve 58 at the time when the gas-liquid discharge valve 58 enters an open state according to its design without any deviation.The normal reference value Ls is set to a discharge gas flow rate that, at a setpoint supply pressure of the anode gas, can reach a setpoint gas discharge quantity (an accumulation value) of the anode exhaust gas at the time when a predetermined time interval has elapsed in the normal gas discharge process after the control section 62 has instructed the gas-liquid discharge valve 58 to be open. For example, the normal reference value Ls is set to a discharge gas flow rate at the time when the valve opening rate of the gas-liquid discharge valve 58 is 50%. In this embodiment, in a case where the valve opening rate is 50%, the setpoint gas discharge quantity of the anode exhaust gas in the normal gas discharge process is 0.1 l when the temperature of the fuel cell 15 (in this embodiment, a measured value of the temperature sensor 73) is 0°C and the setpoint supply pressure of the anode gas is 100 kPa.The predetermined time is determined, for example, taking into account extra time until a reading from pressure sensor 59 becomes stable, in addition to the time required to reach the target gas delivery rate of 0.1 l when the valve opening rate of the gas-liquid delivery valve 58 is 50%. In this embodiment, the predetermined time is, for example, 0.3 s. This means that the normal reference value Ls is set to a delivery gas flow rate of 0.1 l / 0.3 s. The normal reference value Ls can be changed according to the temperature of the fuel cell 15 and the target supply pressure of the anode gas.

[0049] The discharge gas flow rate of the anode gas is acquired by the flow rate acquisition section 66, which is included in the fuel cell system 10. In this embodiment, the flow rate acquisition section is formed by the pressure sensor 59 and the control section 62. The control section 62 acquires the discharge gas flow rate of the anode gas by a calculation that uses the following equations (1) to (4). Pv=f(Qin−Qcrs−QFC−Qex)

[0050] Here, Pv indicates a pressure decrease rate [Pa / s] of the anode gas in the anode gas supply passage 501, which is determined by differentiating a measured value (pressure) of the pressure sensor 59 with respect to time, Q in gives a feed flow rate [m 3 / s] of the anode gas, which is to be supplied from the injector 54 on the downstream side, Q crs gives a hydrogen permeation rate [m 3 / s] from the anode to the cathode in fuel cell 15, Q FC gives an anode gas velocity [m 3 / s] of the anode gas, which is consumed by the power generation of the fuel cell 15, Q ex specifies a delivery gas flow rate [m 3 / s] of the anode gas to be discharged by the gas-liquid discharge valve 58, and f specifies a function. Q in , Q crs , Q FC are by a volume flow [m 3 [ / s] expressed as a gas in a standard state. Q in is calculated by using a throttle equation to determine the pressure difference between the downstream and upstream sides of the passage along injector 54. The determination in step S30, which is in Fig. The process shown in Figure 3 is preferably carried out while the operation of the injector 54 is suspended, i.e., during a closing process. In this case, in Q in “0” was entered. Q crsis calculated based on a hydrogen partial pressure difference between the anode and the cathode. If the determination is carried out in step S30, Q can crs It can be considered "0" because the hydrogen permeation rate is very small.

[0051] Q FC is calculated by the following equation (2). QFC=(I / F)×(1 / 2)×N×22.4×10−3

[0052] Here, I represents a current value [A] measured by the current sensor 72, F represents the Faraday constant, and N is the number of layers of the individual cells 151. This is 22.4 × 10 -3 a volume [m³ 3 / mol] per 1 mol of gas in a standard condition.

[0053] If in equation (1) in Q in “0” and in Q crs Substituting "0" yields equation (3) and equation (3) gives us the following equation (4). Pv=f(−QFC−Qex) Qex=[{V×(Pv / Ps)×(273 / (273+T)}]−QFC

[0054] In equation (4) V gives a volume [m 3 ] through which the anode gas can flow from the injector 54 on the downstream side when the gas-liquid discharge valve 58 is closed, and it is a total volume of part of the anode gas supply passage 501 on the downstream side of the injector 54, a distributor through which the anode gas of the fuel cell 15 flows, the anode gas circulation passage 502, and the gas-liquid separator 57. Furthermore, Ps in equation (4) specifies a standard pressure, which in this embodiment is 101.3 kPa. Additionally, T specifies an ambient temperature [°C] of an environment in which the fuel cell 10 is located, and in this embodiment it is a measured value (°C) of the temperature sensor 73.

[0055] Control section 62 calculates the discharge gas flow rate Q exby substituting equation (2) into equation (4). If the fuel cell 15 does not generate an electric current, Q FC where "0".

[0056] As in Fig. As shown in Figure 3, control section 62 compares the discharge gas flow rate Q. ex of the anode exhaust gas with the normal reference value and performs a normal / deviation determination to see whether the gas-liquid discharge valve 58 is normally open or not by determining whether the discharge gas flow rate Q ex at least the normal reference value is (step S30). More precisely, 0.3 seconds after step S74 in Fig. 4 has been executed, determines that in step S30 in Fig. 3. “Yes” applies if a value obtained by multiplying the discharge gas flow rate calculated by equation (4) by 0.3 seconds is a reference quantity (for example, 0.1 l) or more. In this case, control section 62 makes a normal determination that the gas-liquid discharge valve 58 is normally open (step S40). That is, after control section 62 has instructed the gas-liquid discharge valve 58 to be open, control section 62 makes a normal determination when the discharge gas flow rate Q ex The anode gas from the gas-liquid discharge valve 58 is at least the predetermined normal reference value. After step S40, the control section 62 executes step S50.

[0057] If the discharge gas flow rate Q exHowever, if the anode exhaust gas flow rate is lower than the normal reference value, control section 62 makes a deviation determination that the gas-liquid discharge valve 58 is not open normally (step S60). That is, after control section 62 has instructed the gas-liquid discharge valve 58 to be open, it makes a deviation determination if the discharge gas flow rate Q ex The anode gas from the gas-liquid dispensing valve 58 is less than the predetermined normal reference value. In this case, the control section 62 proceeds to step S70 to notify the driver that the gas-liquid dispensing valve 58 is showing a deviation and terminates the operating determination process without issuing vehicle driving authorization.

[0058] Fig. Figure 6 is a timetable of various processes, including the operating determination process, that are executed by the control section 62. If the start switch is turned on at time t1 and if the temperature acquired by the temperature sensor 73 is below freezing, the sub-freezing start process is executed. When the sub-freezing start process is initiated and the anode gas supply pressure reaches a predetermined setpoint pressure at time t2, the control section 62 instructs the gas-liquid discharge valve 58 to be open. When a predetermined time (e.g., 0.3 seconds) has elapsed after the gas-liquid discharge valve 58 has been instructed to be open at time t2, the control section 62 executes the following in the timetable described in Figure 6. Fig. In step S30, as shown in Figure 3, the normal / deviation determination is carried out. If the gas-liquid discharge valve 58 is classified as normal at time t3, the control section 62 reports vehicle driving authorization. If the interior of the fuel cell 15 has been completely replaced by the anode gas at time t4, the sub-freezing start-up process is terminated. After the sub-freezing start-up process has been terminated, the control section 62 further increases the supply pressure of the anode gas. If, at time t5, when the supply pressure of the anode gas reaches a predetermined target pressure, a current with a threshold value or higher flows by applying a voltage to the fuel cell 15, it is determined that the fuel cell 15 can generate electrical current normally. The driving of the fuel cell vehicle 12 is thus carried out by utilizing the power generation of the fuel cell 15.

[0059] As described above, in the first embodiment, the control section 62 uses the discharge gas flow rate Q to exThe normal / deviation determination for the gas-liquid dispensing valve 58 is performed, making it possible to accurately determine whether the gas-liquid dispensing valve 58 is normally open or not. For example, it is possible to accurately determine that the gas-liquid dispensing valve 58 is not normally open for a reason other than freezing. By performing the normal / deviation determination using the dispensing gas flow rate, it is also possible, for example, to accurately determine that the gas-liquid dispensing valve 58 is not normally open due to freezing. Furthermore, in the first embodiment, the normal / deviation determination is performed when the gas-liquid dispensing valve 58 is instructed to be open during the start-up process, which begins below freezing.This means that if the normal / deviation determination is performed during the execution of the sub-freezing start-up procedure, it can be performed using the sub-freezing start-up procedure itself. This eliminates the need for control section 62 to instruct the gas-liquid discharge valve 58 to be open in order to perform the normal / deviation determination independently of the sub-freezing start-up procedure.

[0060] It should be noted that, in the first embodiment, the control section 62 can control the operation of the injector 54 such that the pressure (determination time pressure) of the anode gas supplied to the fuel cell 15 during the operating determination process is set higher than the pressure (normal time pressure) of the anode gas supplied to the fuel cell 15 during normal gas delivery. The discharge gas flow rate of the anode exhaust from the gas-liquid discharge valve 58 is calculated using a rate of decrease (Pv) of the anode gas pressure. If the pressure of the anode gas supplied to the fuel cell 15 is higher, the influence of other pressure fluctuation disturbances can be relatively reduced. This allows the control section 62 to perform the normal / deviation determination more accurately. If the pressure of the supplied anode gas is higher, the discharge gas flow rate of the anode exhaust gas is also higher.Accordingly, it is possible to shorten the time required for normal / deviation determination. It should be noted that the determination time pressure can be 110% or more of the normal time pressure, or 120% or more. The upper limit of the determination time pressure is set so that it is lower than an upper limit pressure below which various components of the anode gas supply / delivery system 50 will not be damaged. For example, the pressure of the anode gas to be supplied to the fuel cell 15 is used as an average of values ​​measured by the pressure sensor 59.

[0061] In a case where the determination-time pressure is set higher than the normal-time pressure, the control section 62 can also adjust the flow rate (determination-time cathode gas flow rate) of the cathode gas flowing through the cathode gas discharge port 308 to be greater than the flow rate (normal-time cathode gas flow rate) of the cathode gas flowing through the cathode gas discharge port 308 during normal gas discharge. This allows the anode exhaust gas to be diluted by the cathode gas, thus reducing the possibility of gas with a higher hydrogen concentration being discharged to the outside. The flow rate of the cathode gas flowing through the cathode gas discharge port 308 can be increased, for example, by increasing the rotational speed of the compressor 33.Furthermore, the determination time cathode gas flow rate can be 110% or more of the normal time cathode gas flow rate, or 120% or more of the normal time cathode gas flow rate. B. Second embodiment

[0062] Fig. Figure 7 is another flowchart executed by the control device 60 of the fuel cell system 10. The one in Fig. The flowchart shown in section 7 is executed after step S60 in Fig. It has been determined that the gas-liquid discharge valve 58 shows a deviation. It should be noted that the in Fig. 7 Flowchart shown before or after step S70 in Fig. 3 or can be executed instead of step S70.

[0063] First, the control section 62 performs a warm-up operation, which is a process to correct the deviation (step S100). The warm-up operation is only executed for a predetermined time. When the temperature of the fuel cell 15 is increased by the warm-up operation, the gas-liquid dispensing valve 58 located around the fuel cell 15 is heated using heat from the fuel cell 15. This allows the frozen gas-liquid dispensing valve 58 to thaw in case it is not operating normally due to freezing, thus restoring its normal operation. The warm-up operation includes a normal warm-up operation and a rapid warm-up operation, and either operation can be performed.Rapid warm-up operation is an operation in which the cathode gas stoichiometry ratio, which is the ratio of the actual cathode gas supply quantity to a theoretical supply quantity of cathode gas (determined theoretically using the power generation quantity of the fuel cell 15), is set lower than in normal operation of the fuel cell system 10, for which the gas-liquid discharge valve 58 is normally open. In normal operation, the cathode gas stoichiometry ratio is set to approximately 1.5 to 2.0. In rapid warm-up operation, on the other hand, the cathode gas stoichiometry ratio is set to a value close to 1.0, e.g., approximately 0.9 to 1.1. Warm-up operation is an operation in which the cathode gas stoichiometry ratio is higher than in rapid warm-up operation and is at the same level as in normal operation.

[0064] The control section 62 then instructs the gas-liquid discharge valve 58 to be open in order to perform a recovery gas discharge process at a predetermined time during or after the warm-up operation (step S140). The predetermined time is a point in time when the liquid water in the gas-liquid separator 57 has accumulated, for example, the initial quantity of liquid water or more.

[0065] Subsequently, control section 62 performs a recovery determination to ascertain whether the operation of the gas-liquid discharge valve 58 has been restored to normal or not (step S160). More precisely, control section 62 determines that the operation of the gas-liquid discharge valve 58 has been restored to normal when the discharge gas flow rate Q exThe anode exhaust gas from the gas-liquid discharge valve 58 is a predetermined recovery reference value or higher. The control section 62 thus determines that the frozen gas-liquid discharge valve 58 has been thawed by the warm-up operation. If the discharge gas flow rate Q ex However, if the value is smaller than the predetermined recovery reference value, control section 62 determines that the operation of the gas-liquid discharge valve 58 has not been restored to normal. Control section 62 thus determines that the frozen gas-liquid discharge valve 58 has not been thawed by the warm-up operation. The discharge gas flow rate Q exThe recovery reference value is calculated similarly to the first embodiment by using equations (1) to (4). The recovery reference value can be set to the same value as the normal reference value in the first embodiment, or it can be set to a value smaller than the normal reference value. The determination in step S160 is performed, for example, if only a predetermined recovery determination time has elapsed after the operation of step S140 has been executed. The recovery determination time is the time until the discharge gas flow rate Q ex It becomes stable, and is set, for example, to 0.5 seconds. This means that in step S160 it is determined whether a value obtained by multiplying the delivery gas flow rate Q exwith an expired recovery time, if the recovery determination time has expired, is at least a value obtained by multiplying a discharge gas flow rate estimated from a valve opening rate at the time when the recovery reference value is determined by an expired recovery time.

[0066] If control section 62 determines "Yes" in step S160, control section 62 executes a recovery sequence operation (step S170). The recovery sequence operation, at a start-up time before the fuel cell system 10 start switch is turned on and vehicle driving authorization is granted, is an operation in which the vehicle driving authorization is communicated to the driver, or an operation that allows the fuel cell 15 to generate electrical current. Furthermore, the recovery sequence operation, at the time when the start switch is turned off and the fuel cell system 10 is stopped, is an operation that stops the compressor 33 drive.

[0067] However, if control section 62 determines "No" in step S160, control section 62 executes step S140 again.

[0068] The second embodiment provides the following additional effects beyond those of the first embodiment. Specifically, in the second embodiment, the gas-liquid dispensing valve 58 can be heated by utilizing heat from the fuel cell 15 when the temperature of the fuel cell 15 is increased by the heating operation. This allows the frozen gas-liquid dispensing valve 58 to be thawed if it is not open normally due to freezing, thus restoring its normal operation. Furthermore, when the restoration procedure is performed, it is possible to verify whether the operation of the gas-liquid dispensing valve 58 has been restored. C. Third example

[0069] Fig. Figure 8 is another flowchart executed by the control device 60 of the fuel cell system 10. The one in Fig. The flowchart shown in step 8 is executed after step S60 in Fig. It has been determined in section 3 that the gas-liquid discharge valve 58 has a deviation. It should be noted that the in Fig. 8 Flowchart shown before or after step S70 in Fig. 3 or can be executed instead of step S70. Additionally, a step corresponding to the step in the flowchart ( Fig. 7) of the second embodiment, is similar, is provided with the same reference numeral, and a description thereof is omitted.

[0070] First, control section 62 performs a warm-up operation, which is a process that eliminates the deviation (step S100). After the warm-up operation is complete, control section 62 determines whether the fuel cell system 10 is in a light load operating state or not (step S102). The light load operating state indicates a condition in which a load connected to the fuel cell 15 is a predetermined value (e.g., 2 kilowatts) or less, such as during idling operation while the fuel cell vehicle 12 is stopped. If control section 62 determines "No" in step S102, control section 62 terminates the process in the flowchart.

[0071] If, however, the control section 62 determines "Yes" in step S102, it sets a threshold for the liquid water accumulated in the gas-liquid separator 57 to a second liquid water quantity (step S120). This threshold serves as a trigger to instruct the gas-liquid discharge valve 58 to be open. The second liquid water quantity is a quantity smaller than the first liquid water quantity, which serves as the trigger for the normal gas discharge process. In a process after a deviation determination, the control section 62 instructs the gas-liquid discharge valve 58 to be open when the liquid water accumulated in the gas-liquid separator 57 reaches or exceeds the second liquid water quantity. The second liquid water quantity is, for example, preferably 20% of the first liquid water quantity or less, or even better, 10% of the first liquid water quantity or less.This allows the frequency with which the gas-liquid discharge valve 58 is instructed to be open to be increased, thereby increasing the number of times the (later described) recovery determination can be performed.

[0072] The control section 62 then determines whether the amount of liquid water that has accumulated in the gas-liquid separator 57 reaches or exceeds the second liquid water quantity (step S130). If the control section 62 determines "No" in step S130, it repeats step S102. However, if the control section 62 determines "Yes" in step S130, it instructs the gas-liquid discharge valve 58 to be open in order to perform the gas recovery discharge process (step S140).

[0073] Subsequently, control section 62 performs a preliminary operation to more precisely determine the (later described) recovery (step S150). Note that the sequence of steps S140 and S150 can be reversed compared to the above. The preliminary operation includes at least one of the following operations. - First preliminary step: The pressure of the anode gas to be supplied to the fuel cell 15 is made higher than during the execution of the normal gas delivery process. - Second preliminary process: The flow rate of the anode exhaust gas, which is to be circulated from the anode gas circulation passage 502 to the anode gas supply passage 501, is made smaller than during the execution of the normal gas discharge process. - Third preliminary process: A current value of the fuel cell 15 is set lower than during the execution of the normal gas delivery process.

[0074] In the first pre-processing step, the control section 62, for example, shortens or lengthens a valve opening interval of the injector 54 compared to that during the execution of the normal gas delivery process. The supply pressure of the anode exhaust gas in the first pre-processing step can be at least 110% of the supply pressure of the anode gas during the execution of the normal gas delivery process, or it can be at least 120% of the supply pressure of the anode gas during the execution of the normal gas delivery process. An upper limit for the supply pressure of the anode gas in the first pre-processing step is set so that it is lower than the upper limit pressure below which various components of the anode gas supply / delivery system 50 will not be damaged.

[0075] In the second preliminary step, the control section 62, for example, stops the drive of the circulation pump 55 in order to reduce the flow rate of the anode exhaust gas that is to be circulated to the anode gas supply passage 501. In the third preliminary step, the control section 62 sets the current value, for example as a current command value, to zero.

[0076] If at least one of the first pre-operations up to the third pre-operations is executed in step S150, the control section 62 can execute the following fourth pre-operation. - Fourth preliminary process: The flow rate of the cathode gas flowing through the cathode gas discharge passage 308 is made greater than the flow rate of the cathode gas flowing through the cathode gas discharge passage 308 in the normal gas discharge process.

[0077] In the fourth pre-processing step, the control section 62 increases the cathode gas flow rate, for example by increasing the speed of the compressor 33. Furthermore, the cathode gas flow rate in the fourth pre-processing step can be at least 110% or at least 120% of the cathode gas flow rate in the normal gas discharge process. Even if the amount of anode exhaust gas to be discharged to the outside via the gas-liquid discharge valve 58 is increased due to the first, second, or third pre-processing step, the hydrogen gas in the anode exhaust gas can be diluted by the cathode exhaust gas when the fourth pre-processing step is executed. This reduces the possibility of gas with a high hydrogen gas concentration being discharged to the outside via the cathode gas discharge port 308.

[0078] Following step S150, control section 62 performs the recovery determination to ascertain whether the operation of the gas-liquid discharge valve 58 has been restored to normal or not (step S160). If control section 62 determines "Yes" in step S160, control section 62 executes the recovery sequence operation (step S170).

[0079] However, if control section 62 determines "No" in step S160, control section 62 executes step S102 again.

[0080] Fig. Figure 9 is a timeline of step S130, step S140, and step S160, which is in Fig. Figure 8 illustrates this. When the liquid water accumulated in the gas-liquid separator 57, estimated based on the amount of electricity generated by the fuel cell 15, reaches the second liquid water quantity or more (time t10, t14, t18), the control section 62 instructs the gas-liquid discharge valve 58 to be open. In a case where the gas-liquid discharge valve 58 is assumed to be operating normally, when the liquid water is discharged from the gas-liquid discharge valve 58 and the amount of liquid water accumulated in the gas-liquid separator 57 reaches a predetermined value (e.g., zero) or less (time t12, t16), the control section 62 instructs the gas-liquid discharge valve 58 to be closed.While the gas-liquid discharge valve 58 is instructed to be open, the valve opening interval of the injector 54 is shortened compared to normal gas discharge operation, thus increasing the anode gas supply pressure. Simultaneously, while the gas-liquid discharge valve 58 is instructed to be open, the compressor 33 speed is increased compared to normal gas discharge operation, thus increasing the cathode gas flow rate through the cathode gas discharge passage 308. The control section 62 executes the recovery command while the gas-liquid discharge valve 58 is instructed to be open.

[0081] The third embodiment, in addition to the effects similar to those achieved in the first and second embodiments, yields the following effects. Specifically, in a state of the fuel cell system 10 prior to recovery, before the operation of the gas-liquid discharge valve 58 has been restored to normal (i.e., after a predetermined time following the determination process that the gas-liquid discharge valve 58 is not normally open), the control section 62 signals the gas-liquid discharge valve 58 to be open by the recovery gas discharge process (step S140 in...). Fig. 8) While the gas-liquid discharge valve 58 is instructed to be open during the recovery gas discharge process, the control section 62 also performs the recovery determination (step S160 in Fig. 8) When the liquid water reaches at least the second liquid water quantity, which is smaller than the first liquid water quantity, the control section 62 also executes the restoration gas discharge operation. This allows the number of execution times of the restoration gas discharge operation to be increased, thereby increasing the number of times the gas-liquid discharge valve 58 is instructed to be open. Accordingly, it is possible to increase the frequency of the restoration determination, thus preventing a delay in the restoration sequence operation.

[0082] In the third embodiment, when the restoration determination is performed, control section 62 also executes the preliminary process (step S150 in Fig. 8) The control section 62 performs the first pre-processing step, in which the pressure of the anode gas to be supplied to the fuel cell 15 is increased so that it is higher than during the execution of the normal gas delivery process, thereby achieving the following effects. Namely, the delivery gas flow rate Q is increased. ex The anode exhaust gas flow rate from the gas-liquid discharge valve 58 is calculated using the decrease rate (Pv) of the anode gas pressure. If the pressure of the anode gas to be supplied to the fuel cell 15 is higher, the influence of other pressure fluctuation disturbances can be relatively reduced. This allows the control section 62 to perform the recovery determination more accurately. Furthermore, if the pressure of the supplied anode gas is higher, the discharge gas flow rate Q is also higher. exThe anode exhaust gas is higher, which reduces the time required for recovery determination.

[0083] Furthermore, the control section 62 performs a second preliminary process in which the flow rate of the anode exhaust gas circulating from the anode gas circulation port 502 to the anode gas supply port 501 is reduced so that it is lower than during the execution of the normal gas discharge process, thereby achieving the following effects. Specifically, by reducing the flow rate of the circulating anode gas in the anode gas supply port 501 in the area where the pressure sensor 59 is located, pressure pulsation can be suppressed. This reduces pressure fluctuation disturbances, thus enabling more accurate recovery determination.

[0084] Furthermore, the control section 62 performs the third pre-processing step, in which the current value of the fuel cell 15 is reduced so that it is smaller than during the execution of the normal gas delivery process, thereby achieving the following effects.

[0085] Specifically, in fuel cell 15, the amount of anode gas supplied to the fuel cell 15 increases when the current value of the fuel cell 15 increases. Consequently, the pressure fluctuation disturbance measured by pressure sensor 59 also increases. However, if the current value of the fuel cell 15 is adjusted to a low value by the third preliminary process, the amount of anode gas consumed in the fuel cell 15 can be reduced. This makes it possible to reduce the pressure fluctuation disturbance, thereby enabling more accurate recovery determination.

[0086] If, as described above, at least one of the first pre-processing steps is carried out before the third, the possibility that the pressure measured by the pressure sensor 59 will change due to a circumstance other than the anode exhaust gas to be discharged by the gas-liquid discharge valve 58 can be reduced. This can improve the calculation accuracy of the discharge gas flow rate Q. ex further improvements, which makes it possible to perform the recovery determination more accurately. D. Fourth embodiment

[0087] If, in the first embodiment up to the third embodiment, the discharge gas flow rate Q exIf the value is smaller than the normal reference value Ls, the control section 62 determines that the gas-liquid dispensing valve 58 has a deviation. However, the exemplary embodiments are not limited to this. The following describes the content of a further deviation detection test, which is to be performed by the control section 62 using the first exemplary embodiment.

[0088] Fig. 10 is a flowchart for determining the presence of deviations in a fourth embodiment. One step corresponds to a step in the first embodiment in the flowchart in Fig. Items that are similar to item 3 are given the same reference symbol, and a description of them is omitted. Fig. 11 is a view to describe a predetermined reference collection set.

[0089] As in Fig. As shown in Figure 10, the control section 62 executes step S55 if, in step S30, it determines "No," i.e., if, during the normal / deviation determination process, it determines that the gas-liquid discharge valve 58 is not normally open. In step S55, the control section 62 determines whether the accumulation quantity of anode exhaust gas discharged from the gas-liquid discharge passage 504 within a predetermined time period is at least a predetermined reference accumulation quantity. In a case where the accumulation quantity of anode exhaust gas is the predetermined reference accumulation quantity or more, the control section 62 also determines whether the discharge gas flow rate Q exIf the gas-liquid discharge valve 58 is normally open (step S40), the gas-liquid discharge valve 58 is normally open when the amount of discharged anode exhaust gas is less than the predetermined reference amount. However, if the amount of discharged anode exhaust gas is less than the predetermined reference amount, the control section 62 determines that the gas-liquid discharge valve 58 is not normally open (step S60).

[0090] Control section 62 calculates the amount of discharged anode exhaust gas collected (discharge gas collection quantity) by using a pressure drop of the anode gas measured by pressure sensor 59 during an injector 54 operating time interval within a predetermined time interval (e.g., 5 seconds) that is longer than the determination time in step S30. More precisely, control section 62 calculates the discharge gas collection quantity using the following equation (5). Qvex=[{V×(ΔP / Ps)×(273 / (273+T)}]−QvFC

[0091] Qv gives ex V represents the amount of discharge gas accumulated. Furthermore, V specifies the volume through which the anode gas can flow in a closed state of the gas-liquid discharge valve 58 on the downstream side of the injector 54, and which is a total volume comprising part of the anode gas supply passage 501 on the downstream side of the injector 54, the distributor through which the anode gas of the fuel cell 15 flows, the anode gas circulation passage 502, and the gas-liquid separator 57. ΔP specifies the pressure drop of the anode gas measured by the pressure sensor 59 within the predetermined time period. Furthermore, Ps specifies a standard pressure, which in this embodiment is 101.3 kPa, and T specifies an ambient temperature of an environment in which the fuel cell system 10 is placed, which in this embodiment is a measurement taken by the temperature sensor 73. Q VFCSpecifies the amount of anode gas consumed by fuel cell 15 for power generation within the predetermined time period.

[0092] As in Fig. As shown in Figure 11, the predetermined reference accumulation quantity Qvs is calculated based on a cathode exhaust gas discharge flow rate Lp at the time when the valve opening rate of the gas-liquid discharge valve 58 is a value lower than the valve opening rate at the normal reference value Ls. More precisely, the reference accumulation quantity Qvs is a value obtained by multiplying the discharge gas flow rate Lp by the predetermined time interval (e.g., 5 seconds). The valve opening rate corresponding to the discharge gas flow rate Lp can be set within a range in which the target gas discharge quantity of the anode exhaust gas can be achieved in the normal gas discharge process within the predetermined time interval. This prevents the time required to execute the subsequent normal gas discharge process from being extended in a case where the control section 62 determines "Yes" in step S55.

[0093] In the fourth embodiment, the determination of whether the gas-liquid discharge valve 58 is normally open is carried out by two determination methods: one method using the discharge gas flow rate of the anode exhaust gas, and another method using the gas discharge quantity of the anode exhaust gas. This makes it possible to determine more accurately whether the gas-liquid discharge valve 58 is normally open. If the normal reference value Ls is set to, for example, a safe value, the control section 62 determines in step S30 whether the gas-liquid discharge valve 58 is normally open or not. If the gas-liquid discharge valve 58 is not normally open, it can be determined whether the gas-liquid discharge valve 58 is normally open again by using the reference accumulation quantity Qvs. E. Further embodiment examples E-1. Further embodiment example 1

[0094] In each of the above embodiments, the control section 62 performs the normal / deviation determination to determine whether the gas-liquid dispensing valve 58 is operating normally ( Fig. 3), if the temperature sensor 73 ( Fig. 1) acquired temperature is the freezing point or below. However, normal / deviation determination can also be performed in other cases. For example, the control section 62 can perform normal / deviation determination when the temperature measured by the temperature sensor 73 ( Fig. 1) The acquired temperature is not the freezing point or below. Even in such a case, it is possible to accurately determine whether the gas-liquid discharge valve 58 is operating normally. E-2. Further embodiment example 2

[0095] In each of the above embodiments, the flow rate acquisition section is formed by the control section 62 and the pressure sensor 59, and the control section 62 calculates the discharge gas flow rate Q. ex by using a pressure acquired by the pressure sensor 59. However, the embodiments are not limited to this. In the gas-liquid discharge passage 504, a flow meter can be placed near an outlet of the gas-liquid discharge valve 58, so that the flow meter acts as the flow rate acquisition section. E-3. Further embodiment example 3

[0096] In the third embodiment, the restoration reference value can be a discharge gas flow rate of the cathode exhaust gas at a valve opening rate that is lower than a valve opening rate at the normal reference value and higher than a valve opening rate that corresponds to the discharge gas flow rate Lp. E-4. Further embodiment 4

[0097] In the second or third embodiment, if the control section 62 determines during the operating procedure that the gas-liquid discharge valve 58 is not normally open, the control section 62 performs the warm-up operation to increase the temperature of the fuel cell 15. However, these embodiments are not limited to this. The control section 62 can perform an operation to increase the temperature of the gas-liquid discharge valve 58 by using other methods. For example, the control section 62 can increase the temperature of the gas-liquid discharge valve 58 by heating it with a heater.

Claims

[1] Fuel cell system (10) with: a fuel cell (15); an anode gas supply system (50A) configured to supply anode gas to the fuel cell (15), wherein the anode gas supply system (50A) includes an anode gas supply passage (501) through which the anode gas flows towards the fuel cell (15); an anode gas circulation system (50B) configured to circulate anode exhaust gas discharged from the fuel cell (15) to the anode gas supply passage (501), wherein the anode gas circulation system (50B) an anode gas circulation passage (502) through which the anode exhaust gas flows towards the anode gas supply passage (501), and a gas-liquid separator (57) which is provided in the anode gas circulation passage (502) and is configured to separate liquid water from the anode exhaust gas; a cathode gas supply and delivery system (30) which a cathode gas supply passage (302) configured to supply cathode gas to the fuel cell (15), and includes a cathode gas discharge passage (308) through which cathode gas discharged from the fuel cell (15) is discharged to an outside of the fuel cell system (10); a gas-liquid discharge passage (504) which is connected to the gas-liquid separator (57); a gas-liquid dispensing valve (58) provided in the gas-liquid dispensing passage (504) and configured to open and close the gas-liquid dispensing passage (504); a flow rate acquisition section (66) configured to acquire a discharge gas flow rate of the anode exhaust gas discharged from the gas-liquid discharge valve (58); and a control section (62) configured to perform an operating determination process which includes a normal / deviation determination of whether the gas-liquid dispensing valve (58) is normally open or not, wherein the control section (62), after instructing the gas-liquid dispensing valve (58) to be open, performs the normal / deviation determination such that The control section (62) determines that the gas-liquid discharge valve (58) is normally open when the discharge gas flow rate of the anode exhaust gas is a predetermined normal reference value or higher, and The control section (62) determines that the gas-liquid discharge valve (58) is not normally open when the discharge gas flow rate of the anode exhaust is less than the predetermined normal reference value. characterized by a water storage quantity acquisition section (67) configured to acquire a quantity of the liquid water accumulated in the gas-liquid separator (57), wherein: the control section (62) in a normal operating state of the fuel cell system (10), in which the gas-liquid discharge valve (58) is normally open, in a case where the amount of liquid water accumulated in the gas-liquid separator (57) is a predetermined initial liquid water quantity or more, performs a normal gas discharge operation by controlling the anode gas supply system (50A) to supply the anode gas to the fuel cell (15) and instructing the gas-liquid discharge valve (58) to be open; and a pressure of the anode gas to be supplied to the fuel cell (15) during the operating determination process is higher than a pressure of the anode gas to be supplied to the fuel cell (15) during the normal gas delivery process. [2] Fuel cell system (10) according to claim 1, further comprising a temperature acquisition section (73) configured to acquire an ambient temperature of the fuel cell system (10), wherein: the control section (62), in a case where it receives an activation instruction to activate the fuel cell system (10), performs a sub-freezing start-up operation when the ambient temperature is at or below freezing by controlling the anode gas supply system (50A) to supply the anode gas to the fuel cell (15) and instructing the gas-liquid discharge valve (58) to be open; and the control section (62) performs the normal / deviation determination after the control section (62) has instructed the gas-liquid discharge valve (58) to be open in the start-up process beginning below freezing. [3] Fuel cell system (10) according to claim 1 or 2, wherein: the cathode gas supply and discharge system (30) also includes a compressor (33) which is provided in the cathode gas supply passage (302); the gas-liquid discharge port (504) is connected to the cathode gas discharge port (308); and the control section (62) controls the operation of the compressor (33) such that a flow rate of the cathode gas flowing through the cathode gas discharge passage (308) during the operating determination process is greater than a flow rate of the cathode gas flowing through the cathode gas discharge passage (308) during the normal gas discharge process. [4] Fuel cell system (10) according to claim 2, wherein: the control section (62) performs a warm-up operation to increase the temperature of the fuel cell (15) after determining in the operating determination process that the gas-liquid discharge valve (58) is not open normally; the control section (62) performs a restoration determination, at least during or after the execution of the warm-up operation, as to whether the operation of the gas-liquid discharge valve (58) has been restored to normal or not; and After the control section (62) has instructed the gas-liquid discharge valve (58) to be open, the recovery determination is carried out such that The control section (62) determines that the operation of the gas-liquid discharge valve (58) is restored to normal when the discharge gas flow rate of the anode exhaust gas is a predetermined restoration reference value or more, and The control section (62) determines that the operation of the gas-liquid discharge valve (58) is not restored to normal if the discharge gas flow rate of the anode exhaust is less than the predetermined restoration reference value. [5] Fuel cell system (10) according to claim 4, wherein: the control section (62) in a state of the fuel cell system (10) prior to recovery, before the operation of the gas-liquid discharge valve (58) has been restored to normal, performs a recovery gas discharge operation by instructing the gas-liquid discharge valve (58) to be open when the amount of liquid water accumulated in the gas-liquid separator (57) reaches at least a second quantity of liquid water that is less than the first quantity of liquid water; and the control section (62) performs the restoration determination after the control section (62) has instructed the gas-liquid discharge valve (58) to be open in the restoration gas discharge process. [6] Fuel cell system (10) according to claim 5, further comprising a pressure sensor (59) configured to measure a pressure within the anode gas supply passage (501), wherein: the flow rate acquisition section (66) calculates the discharge gas flow rate of the anode exhaust gas by using a change in the pressure measured by the pressure sensor (59); The control section (62) performs at least one of the following operations in a case where the recovery determination is carried out: a first preliminary process in which the pressure of the anode gas to be supplied to the fuel cell (15) is increased so that it is higher than the pressure of the anode gas to be supplied to the fuel cell (15) during the execution of the normal gas delivery process; a second preliminary process in which the flow rate of the anode exhaust gas to be circulated from the anode gas circulation passage (502) to the anode gas supply passage (501) is reduced so that it is smaller than the flow rate of the anode exhaust gas to be circulated from the anode gas circulation passage (502) to the anode gas supply passage (501) during the execution of the normal gas discharge process; and a third preliminary process in which a current value of the fuel cell (15) is reduced so that it is smaller than a current value of the fuel cell (15) during the execution of the normal gas delivery process. [7] Fuel cell system (10) according to claim 6, wherein: the cathode gas supply and discharge system (30) includes a compressor (33) configured to send the cathode gas towards the cathode gas discharge passage (308); the gas-liquid discharge port (504) is connected to the cathode gas discharge port (308); and the control section (62) controls the operation of the compressor (33) such that a flow rate of the cathode gas flowing through the cathode gas discharge passage (308) at a time when the recovery determination is carried out is greater than a flow rate of the cathode gas flowing through the cathode gas discharge passage (308) during the normal gas discharge process. [8] Fuel cell system (10) according to any one of claims 4 to 7, wherein: The control section (62) determines that the gas-liquid discharge valve (58) is normally open in a case where an accumulation quantity of the anode exhaust gas discharged from the gas-liquid discharge passage (504) within a predetermined time period is a predetermined reference accumulation quantity or more, after the control section (62) has instructed the gas-liquid discharge valve (58) to be open, after the control section (62) has determined during the normal / deviation determination that the gas-liquid discharge valve (58) is not normally open, but before the recovery determination is performed, even if the discharge gas flow rate of the anode exhaust gas is less than the normal reference value.

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