JP2004192919A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel gas leakage detection technique for a fuel cell system suitable for a vehicular on-board generator. <P>SOLUTION: In stopping this system, a gas pressure value of a piping system of the fuel cell is previously stored in a nonvolatile memory. When the system is started, the present gas pressure value of the piping system is detected, and compared with the gas pressure value stored in the nonvolatile memory to obtain a pressure drop rate. When the pressure drop rate is smaller than a threshold value corresponding to the elapsed time during the system stop, it is determined to be fuel gas leakage. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

TECHNICAL FIELD OF THE INVENTION
The present invention relates to a gas leak detection technique for a fuel cell system, and more particularly to a fuel gas leak detection technique suitable for an in-vehicle fuel cell system.
[Prior art]
The fuel cell has a stack structure in which a single cell composed of an anode electrode (hydrogen electrode) and a cathode electrode (oxygen electrode) which are arranged to face each other with an electrolyte membrane interposed therebetween. A fuel gas containing hydrogen is supplied to the anode, while an oxidizing gas containing oxygen is supplied to the cathode, and an electromotive force is obtained by an electrochemical reaction occurring on each electrode. If the electrolyte membrane is damaged due to aging or the like, and leakage and permeation of the combustion gas occurs between the two electrodes, a local exothermic reaction or the like may occur and the fuel cell may be damaged. Similarly, in the reformer, if the fuel gas leaks, abnormal combustion may occur in the catalyst, and the fuel may be burned. Therefore, in order to operate the fuel cell system, it is necessary to take measures against fuel gas leakage. JP-A-8-329965 (Patent Literature 1) and JP-A-3-250564 (Patent Literature 2) disclose a fuel cell provided with a pressure detecting means for detecting gas leakage. A power generation system is disclosed. Gas leakage can be detected by detecting a change in gas pressure in the piping system of the fuel cell.
[Patent Document 1]
JP-A-8-329965
[Patent Document 2]
JP-A-3-250564
[Problems to be solved by the invention]
However, the above-described prior art is based on a plant fuel cell system having a small load change, and is difficult to apply to a vehicle-mounted fuel cell system having a large load change. In other words, when the on-board fuel cell system is operated as an on-board generator, it is necessary to appropriately adjust the flow rates of the fuel gas and the oxidizing gas according to the traveling load and the like, so that the gas pressure supplied to the fuel cell constantly changes. In an environment that fluctuates.
Under such an environment, it is difficult to detect fuel gas leakage even when detecting gas pressure fluctuations inside the fuel cell during system operation.
Therefore, an object of the present invention is to propose a fuel gas leak detection technique suitable for operating a fuel cell system as an onboard generator of a vehicle.
[Means for Solving the Problems]
A fuel cell system according to the present invention includes a fuel cell that receives power of a fuel gas and an oxidizing gas to generate power, an input path of a fuel gas supplied to the fuel cell, and an output of a hydrogen off-gas discharged from the fuel cell. A first piping system that constitutes a path, an input path for an oxidizing gas supplied to the fuel cell, a second piping system that constitutes an output path for oxygen off-gas discharged from the fuel cell, The piping system, and a pressure sensor that detects a gas pressure value of the second piping system, the first piping system, and a valve mechanism that shuts off the gas flow of the second piping system, and a system stopped state Time lapse measurement means for measuring the time lapse, storage means for storing the gas pressure value detected by the pressure sensor, and a control unit for performing system control, the control unit, when the system is stopped, the control unit, the valve mechanism System While shutting off the gas flow path of the first piping system and the second piping system and storing the gas pressure value detected by the pressure sensor when the system is stopped, The presence or absence of gas leakage is determined from the relationship between the gas pressure value detected by the pressure sensor after the lapse of time, the gas pressure value stored in the storage means, and the lapse of time measured by the time lapse measurement means. With this configuration, it is possible to detect the leakage of the fuel gas from the fluctuations in the gas pressure values in the first and second piping systems after the system is started, so that the fuel cell system is suitable for an in-vehicle fuel cell system.
Preferably, the control unit obtains a pressure fluctuation amount from a gas pressure value detected by the pressure sensor after a predetermined time has elapsed from a system stop, and a gas pressure value stored in the storage means, The presence or absence of gas leakage is determined from the relationship between the pressure fluctuation amount and the threshold value, which serves as a gas leakage determination criterion corresponding to the elapsed time measured. The presence / absence of gas leakage can be more accurately determined from the relationship between the threshold value and the pressure fluctuation amount, which are the criteria for determining gas leakage.
Preferably, the control unit obtains a pressure fluctuation amount from a gas pressure value detected by the pressure sensor at the time of starting the system and a gas pressure value stored in the storage unit, and calculates a time lapse amount measured by the time lapse measurement unit. The presence or absence of gas leakage is determined from the relationship between a threshold value serving as a gas leakage determination reference corresponding to the pressure fluctuation amount and the pressure fluctuation amount. By comparing the amount of pressure fluctuation at the time of starting the system with a threshold that is a criterion for determining gas leakage, it is possible to determine whether it is safe to permit the start of the system.
Further, the fuel cell system of the present invention includes a fuel cell that generates power by receiving a supply of a fuel gas and an oxidizing gas, an input path of the fuel gas supplied to the fuel cell, and a hydrogen off-gas discharged from the fuel cell. A first piping system constituting an output path of, an input path of oxidizing gas supplied to the fuel cell, a second piping system constituting an output path of oxygen off gas discharged from the fuel cell, A pressure sensor for detecting a gas pressure value of the first piping system and the second piping system, a valve mechanism for shutting off a gas flow of the first piping system and the second piping system, and a system stop Time lapse measuring means for measuring the lapse of time from a point in time, storage means for storing a gas pressure value detected by the pressure sensor, and a control unit for performing system control, the control unit, when the system is stopped, While controlling a mechanism to cut off the gas flow path of the first piping system and the second piping system, a gas pressure value detected by the pressure sensor when the system is stopped is stored in the storage means, The presence or absence of gas leakage is determined based on the relationship between the gas pressure value detected by the pressure sensor at the time when the elapsed time measured by the progress measuring means reaches a predetermined time and the gas pressure value stored in the storage means. Judge. With this configuration, even when the system suspension period is long, the leakage of the fuel gas can be detected from the gas pressure change rate after the lapse of a certain period, so that the safety of the system can be improved.
Preferably, the control unit includes: a gas pressure value detected by the pressure sensor at a point in time when a time lapse measured by the time lapse measurement unit reaches a predetermined time; and a gas stored in the storage unit. The pressure fluctuation amount is obtained from the pressure value, and the presence or absence of gas leakage is determined from the relationship between the threshold value serving as a gas leakage determination reference and the pressure fluctuation amount. The presence / absence of gas leakage can be more accurately determined from the relationship between the threshold value and the pressure fluctuation amount, which are the criteria for determining gas leakage.
Preferably, the pressure fluctuation amount is a ratio between a gas pressure value stored in the storage means and a gas pressure value detected by the pressure sensor at a point in time when a predetermined time has elapsed since the system was stopped. By calculating the ratio between the gas pressure value at the time of system stop and the gas pressure value after a lapse of a predetermined time from the system stop (for example, the next system start time), it is possible to quantitatively determine how much the gas pressure has dropped. It can be grasped and is suitable for determining the presence or absence of gas leakage.
Preferably, when the control unit determines that a gas leak has occurred, the control unit limits the restart of the system. When it is determined that a gas leak has occurred, the safety of the fuel cell system can be improved by limiting the restart of the system.
Preferably, the control unit controls the valve mechanism such that the residual gas pressure in the first piping system is higher than the residual gas pressure in the second piping system when the system is stopped. With this configuration, it is possible to detect whether the gas leak occurs only on the hydrogen electrode side of the fuel cell or on both the hydrogen electrode side and the oxygen electrode side.
Preferably, the fuel cell system is a power generation system mounted on a vehicle. Since a vehicle-mounted power generation system alternately and frequently repeats system operation and system shutdown, gas leakage can be detected by detecting gas pressure fluctuations during the system shutdown period.
The fuel cell vehicle of the present invention includes the fuel cell system of the present invention as an electric power source for driving a vehicle. With this configuration, it is possible to provide a fuel cell vehicle having excellent reliability and safety.
A computer program according to the present invention includes: a computer system that controls a fuel cell system; determining whether a system stop command is input during system operation; and Controlling a valve mechanism disposed in a first piping system constituting an input path of a supplied fuel gas and an output path of a hydrogen off-gas discharged from the fuel cell to cut off a gas flow; Controlling the valve mechanism disposed in the second piping system constituting the input path of the oxidizing gas supplied to the battery and the output path of the oxygen off-gas discharged from the fuel cell, and blocking the gas flow; Storing the gas pressure values in the first piping system and the second piping system when the system is stopped. Determining whether or not a start command is input; and, when the system start command is input, the gas in the first piping system and the second piping system at the time when the system start command is input. A step of determining the presence or absence of gas leakage from the relationship between the pressure value, the gas pressure value stored at the time of the system stop, and the system stop time. By causing the computer system that controls the fuel cell system to execute the above steps, the leakage of the fuel gas can be detected at the time of starting the system, so that the system is suitable for an in-vehicle fuel cell system.
Preferably, the step of judging the presence / absence of gas leakage includes storing the gas pressure values in the first piping system and the second piping system at the time when a system start command is input, and storing the gas pressure values when the system is stopped. In this step, the pressure fluctuation amount is determined from the gas pressure value, and the presence or absence of gas leakage is determined from the relationship between the pressure fluctuation amount and a threshold value serving as a gas leakage determination reference corresponding to the system stop time. The presence / absence of gas leakage can be more accurately determined from the relationship between the threshold value and the pressure fluctuation amount, which are the criteria for determining gas leakage.
Preferably, the pressure fluctuation amount is a ratio between a gas pressure value stored when the system is stopped and a gas pressure value at the time when a system start command is input. By calculating the ratio between the gas pressure value when the system is stopped and the gas pressure value when the system start command is input, it is possible to quantitatively grasp how much the gas pressure has dropped, It is suitable for determining the presence or absence of
The computer system of the present invention includes a step of determining whether or not a system stop command is input during system operation to a computer system that controls the fuel cell system; and Controlling a valve mechanism disposed in a first piping system constituting an input path of a supplied fuel gas and an output path of a hydrogen off-gas discharged from the fuel cell to cut off a gas flow; Controlling the valve mechanism disposed in the second piping system constituting the input path of the oxidizing gas supplied to the battery and the output path of the oxygen off-gas discharged from the fuel cell, and blocking the gas flow; Storing a gas pressure value in the first piping system and the second piping system when the system is stopped; and determining whether a predetermined time has elapsed. And the gas pressure values in the first piping system and the second piping system after the lapse of the certain time, and the gas pressure value stored when the system is stopped after the lapse of the certain time. Determining the presence or absence of gas leakage from the relationship. By causing the computer system that controls the fuel cell system to execute the above steps, even if the system shutdown period is long, the fuel gas leak can be detected from the gas pressure change rate after a certain period, so that the safety of the system can be improved. Can be enhanced.
Preferably, the step of judging the presence or absence of the gas leak is a gas pressure value in the first piping system and the second piping system at the time when the certain time is reached, and stored when the system is stopped. In this step, the amount of pressure fluctuation is determined from the gas pressure value, and the presence or absence of gas leakage is determined from the relationship between the threshold value serving as a gas leakage determination reference and the amount of pressure fluctuation. The presence / absence of gas leakage can be more accurately determined from the relationship between the threshold value and the pressure fluctuation amount, which are the criteria for determining gas leakage.
Preferably, when it is determined in the step of determining the presence or absence of gas leakage that a gas leakage has occurred, the computer system further executes a step of restricting system restart. When it is determined that a gas leak has occurred, the step of restricting the restart of the system is performed by the computer system, whereby the safety of the fuel cell system can be improved.
Preferably, the pressure fluctuation amount is a ratio between a gas pressure value stored when the system is stopped and a gas pressure value at a point in time when the certain period has elapsed since the system was stopped.
By calculating the ratio between the gas pressure value when the system is stopped and the gas pressure value at the time when the certain period has elapsed, it is possible to quantitatively grasp how much the gas pressure has dropped, and to determine whether there is gas leakage. It is suitable for the judgment.
As a computer-readable recording medium for recording the program of the present invention, for example, an optical recording medium (CD-RAM, CD-ROM, DVD-RAM, DVD-ROM, DVD-R, PD disk, MD disk, MO disk, etc.) A magnetic recording medium such as a flexible disk, a magnetic card, and a magnetic tape, or a memory element (a semiconductor such as a DRAM). A portable recording medium such as a memory cartridge provided with a memory element and a ferroelectric memory element such as an FRAM) is suitable.
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present embodiment will be described with reference to the drawings.
FIG. 1 is a main block diagram of a vehicle (fuel cell vehicle) equipped with the fuel cell system of the present embodiment. As shown in FIG. 1, the fuel cell vehicle 10 mainly includes a fuel cell system 20 functioning as an on-board generator, a secondary battery 30 functioning as an auxiliary power source, and a power control unit 40 performing power conversion control. And a motor 50 that drives driving wheels 51 and 52 with electric power supplied from the fuel cell system 20 or the secondary battery 30 via the power control unit 40. The fuel cell vehicle 10 employs a front wheel drive system, and driven wheels 53 and 54 are arranged at the rear of the vehicle.
The fuel cell system 20 includes a tank 21 that separately stores a hydrocarbon-based raw fuel such as methanol or natural gas and water, and a hydrogen-rich mixture obtained by reforming a mixed solution of the raw fuel and water supplied from the tank 21. The fuel cell system includes a reformer 22 that generates fuel gas, a fuel cell 23 that converts chemical energy of the fuel gas supplied from the reformer 22 into electric energy, and a control unit 24 that controls the entire fuel cell system 20. It is configured. The control unit 24 communicates with a system controller 43 to be described later to control the operating speed of an air compressor and a water pump provided in the fuel cell system 20 and to control the opening and closing of a solenoid valve. System control is performed to satisfy the required power. An air cleaner 56 and an air pump 55 are provided in the air flow path of the fuel cell system 20. The power generation air (oxidizing gas) filtered by the air cleaner 56 is pressurized by the air pump 55, and the oxygen of the fuel cell 23 is increased. Supplied to the pole.
The fuel cell 23 is a solid polymer electrolyte type fuel cell and has a stack structure in which a plurality of single cells are stacked. Polymer electrolyte fuel cells have the advantages of being able to start at room temperature, have a short start-up time, obtain a high current density at room temperature, can operate at low loads, and can be reduced in size and weight. It has excellent characteristics as a battery.
The power control unit 40 includes a system controller 43 that detects a running load from an accelerator opening, a vehicle speed, a shift position, a brake depression amount, and the like to calculate an amount of electric power supplied to the motor 50, and a DC / DC converter that transforms a DC voltage. 41, and an inverter 42 that converts a DC current into an AC current and supplies the AC current to the motor 50. Inverter 42 includes a power switch element as a main circuit element, and converts a DC current into a three-phase AC. Power conversion in the DC / DC converter 41 and the inverter 42 is controlled by the system controller 43.
The secondary battery 30 serves as a power source for starting the fuel cell system 20, a regenerative energy storage source during brake regeneration, and an energy buffer when a load changes due to acceleration or deceleration of the fuel cell vehicle 10. Cadmium storage batteries, nickel-metal hydride storage batteries, lithium secondary batteries and the like are suitable. The capacity of the secondary battery 30 can be appropriately set according to the driving conditions, the driving performance (the maximum speed, the driving distance, and the like) of the fuel cell vehicle 10, the vehicle weight, and the like. As the motor 50, a three-phase synchronous motor is preferable.
With the above-described configuration, the system controller 43 calculates the electric power to be supplied to the motor 50 based on the vehicle running load and the like, and issues an instruction necessary to obtain a desired power generation amount in the fuel cell system 20 to the control unit 24. Give to. The control unit 24 appropriately adjusts the flow rates of the fuel gas and the oxidizing gas to be supplied to the fuel cell 23, and obtains electric power required for traveling. The electric power generated by the fuel cell system 20 is supplied to the motor 50 and other accessories via the power control unit 40.
FIG. 2 is an exploded perspective view of a single cell 60 which is a structural unit of the fuel cell 23. The single cell 60 includes an electrolyte membrane 61, an anode 62, a cathode 63, and separators 64 and 65. The anode electrode 62 and the cathode electrode 63 are diffusion electrodes having a sandwich structure with the electrolyte membrane 61 sandwiched from both sides. The separators 64 and 65 composed of gas-impermeable conductive members form fuel gas and oxidizing gas channels between the anode electrode 62 and the cathode electrode 63 while sandwiching the sandwich structure from both sides. . On both surfaces of the separator 64, ribs 64a and 64b having a concave cross section are formed in directions orthogonal to each other. The rib 64a closes the groove-shaped opening by contacting the anode electrode 62 to form a fuel gas flow path. The rib 64b forms an oxidizing gas flow path between adjacent single cells. On both surfaces of the separator 65, ribs 65a and 65b having a concave cross section are formed in directions orthogonal to each other. The rib 65a abuts the cathode electrode 63 to close the groove-shaped opening, thereby forming an oxidizing gas flow path. The rib 65b forms a fuel gas flow path between adjacent single cells.
However, the ribs 64b and 65b are not necessarily required, and can be omitted as appropriate.
The anode electrode 62 is composed of a porous support layer 62a and a hydrogen electrode catalyst layer 62b, and the cathode electrode 63 is composed of a porous support layer 63a and an oxygen electrode catalyst layer 63b. The porous support layers 62a, 63a are both formed of carbon cloth, carbon paper, or carbon felt woven with carbon fiber yarns.
The hydrogen electrode catalyst layer 62b and the oxygen electrode catalyst layer 63b are formed by applying platinum as a catalyst or an alloy made of platinum and another metal to the surface of the electrolyte membrane 61. More specifically, a powder obtained by dispersing carbon powder carrying platinum or an alloy of platinum and another metal in an appropriate organic solvent, adding an appropriate amount of an electrolyte solution to form a paste, and screen-printing on the electrolyte film 61 It is. The electrolyte membrane 61 is a proton-conductive ion exchange membrane formed of a solid polymer material, for example, a fluorine-based resin, and exhibits good electric conductivity in a wet state. In this embodiment, a Nafion film having a thickness of 20 to 70 μm is used. A membrane-electrode assembly (MEA) is formed by the electrolyte membrane 61, the anode 62, and the cathode 63.
FIG. 3 is a system configuration diagram mainly showing a main part of the fuel cell system. As shown in the figure, the reformer 22 includes an evaporator 22a for vaporizing the raw fuel, a reformer 22b for reforming the vaporized raw fuel to a hydrogen-rich fuel gas, and a fuel gas contained in the fuel gas. And a CO reduction unit 22c for removing carbon monoxide (CO). The evaporator 22a is a heat exchange device that exchanges heat between the combustion gas and the liquid-phase raw fuel to vaporize the raw fuel. The raw fuel is supplied from the above-described tank 21 to the raw fuel flow path on the refrigerant side provided in the evaporating section 22a.
The raw fuel is methane (CH ₄ ), Ethane (C ₂ H ₅ ), Propane (C ₃ H ₈ ), Butane (C ₄ H ₁₀ ), Gasoline, light oil, natural gas, methanol (CH ₃ OH), ethanol (C ₂ H ₅ OH), DME (CH ₃ OCH ₃ ), Acetone (CH ₃ C (= O) CH ₃ ) Can be used, but the case where methanol is used is exemplified here. The ratio of the raw fuel composed of a mixed solution of methanol and water, that is, the molar ratio of water / methanol is preferably in the range of 1.0 to 5.0, and more preferably in the range of 1.5 to 3.0.
On the other hand, a mixed gas of fuel and air is supplied to a combustion gas passage on the combustion side provided in the evaporating section 22a, and is burned by the action of an electrocatalyst heater provided in the passage. . In the process of moving downstream, the combustion gas is released to the outside while performing heat exchange with the raw fuel. As the fuel, methanol, gasoline, hydrogen off-gas discharged from the fuel cell 23, or the like is preferable. The amount of heat generated in the evaporator 22a is controlled by the weight of the fuel and the number of revolutions of the combustion air compressor 76.
The vaporized raw fuel gas is supplied to the reforming section 22b, and is reformed into a hydrogen-rich fuel gas by an autothermal method using both steam reforming and partial oxidation reforming. Inside the reforming unit 22b, a copper-zinc-based catalyst (Cu-Zn-based catalyst), a copper-zinc-chromium-based catalyst (Cu-Zn-Cr-based catalyst), and a copper-zinc-aluminum-based catalyst (Cu-Zn-based catalyst) are provided. -Al-based catalyst) and a reforming catalyst such as a zinc-chromium-based catalyst (Zn-Cr-based catalyst), and are kept in a temperature range (200 to 600 ° C) suitable for combined reforming. Oxygen (reforming air) necessary for partial oxidation reforming can be introduced into the reforming section 22b by opening the reforming air shut-off valve 86.
The hydrogen-rich fuel gas generated in the reforming unit 22b is supplied to the CO reducing unit 22c. The CO reduction unit 22c is filled with a carrier carrying a platinum catalyst, a ruthenium catalyst, a palladium catalyst, a gold catalyst, or an alloy catalyst using these as the first element, which are selective oxidation catalysts for carbon monoxide. Purification air containing oxygen required for the selective oxidation reaction of carbon monoxide can be introduced into the CO reduction unit 22c by opening the purification air shut-off valve 87. In order to favorably promote the cell reaction in the fuel cell 23, the concentration of carbon monoxide in the fuel gas is desirably about several ppm or less.
Next, a piping configuration centering on the fuel cell 23 will be described. The fuel cell 23 has a fuel gas introduction pipe 71 for introducing a fuel gas to the anode, an exhaust pipe 72 for discharging hydrogen off-gas used for the cell reaction, and a bypass provided in parallel with the fuel cell 23. A pipe 73, an oxidizing gas introduction pipe 74 for supplying an oxidizing gas to the cathode electrode, and an exhaust pipe 75 for discharging the oxygen off gas used for the battery reaction are provided, respectively, and constitute a piping system of the system. ing.
In this specification, the input path of the fuel gas supplied to the fuel cell 23 and the output path of the hydrogen off-gas discharged from the fuel cell 23 may be collectively referred to as a first piping system. In the present embodiment, the first piping system includes a fuel gas introduction pipe 71, an exhaust pipe 72, and a bypass pipe 73. Further, the input path of the oxidizing gas supplied to the fuel cell 23 and the output path of the oxygen off-gas discharged from the fuel cell 23 may be collectively referred to as a second piping system. In this embodiment, the second piping system includes an oxidizing gas introduction pipe 74 and an exhaust pipe 75. Here, the first piping system and the second piping system can be appropriately designed and changed according to the system configuration, and are not limited to the above-described configuration. Although not shown in the figure, a condensed water recovery device is provided downstream of the exhaust pipe 75, and condenses oxygen off-gas containing water generated by the battery reaction, thereby removing water. It is collected and returned to the tank 21.
An upstream end of the fuel gas introduction pipe 71 is connected to a fuel gas discharge hole of the reformer 22, while a downstream end thereof is connected to a fuel gas flow path inside the fuel cell 23. On the flow path of the fuel gas introduction pipe 71, a reformer pressure adjusting valve 81 and a fuel gas cutoff valve 82 are sequentially arranged from upstream to downstream. The reformer pressure adjusting valve 81 is for adjusting the flow rate of the fuel gas supplied to the fuel cell 23, and is disposed upstream of the junction of the fuel gas introduction pipe 71 and the bypass pipe 73. The fuel gas shut-off valve 82 is a shut-off valve provided on the fuel gas introduction pipe 71, and is disposed downstream from a junction of the fuel gas introduction pipe 71 and the bypass pipe 73. On the other hand, the upstream end of the exhaust pipe 72 is connected to a fuel gas flow path inside the fuel cell 23, and the downstream thereof joins a bypass pipe 73. On the flow path of the exhaust pipe 72, a hydrogen electrode pressure adjusting valve 83 for adjusting the flow rate of the hydrogen off-gas is provided upstream of the junction of the exhaust pipe 72 and the bypass pipe 73.
A fuel gas exhaust valve 84 is provided on the flow path of the bypass pipe 73, and shuts off the fuel gas flowing through the bypass pipe 73 by closing the fuel gas. When the fuel gas exhaust valve 84 is opened with the fuel gas shut-off valve 82 closed, the fuel gas introduced into the fuel gas introduction pipe 71 bypasses the fuel cell 24 and passes through the exhaust pipe 72, and the evaporator 22a Reflux. An air compressor 77 for power generation is disposed at an upstream end of the oxidizing gas introduction pipe 74, and a downstream end thereof is connected to an oxidizing gas flow path inside the fuel cell 23. By adjusting the number of revolutions of the power generation air compressor 77, it is possible to supply the fuel cell 23 with an oxidizing gas sufficient to generate power according to the power supply load. An upstream end of the exhaust pipe 75 is connected to an oxidizing gas flow path inside the fuel cell 23, and a downstream end thereof is connected to a condensed water collector (not shown). An oxygen pole pressure regulating valve 85 for regulating the flow rate of the oxygen off-gas is provided in the flow path of the exhaust pipe 75.
In the above configuration, in an excessive state at the time of starting the system, the fuel gas exhaust valve 84 is adjusted while the opening degrees of the reformer pressure adjusting valve 81, the hydrogen electrode pressure adjusting valve 83, and the oxygen electrode pressure adjusting valve 85 are adjusted appropriately. While the fuel gas shutoff valve 82 is kept closed, and waits until the system is sufficiently warmed up. The fuel gas generated by the reformer 22 is introduced into the evaporator 22a through the fuel gas introduction pipe 71, the bypass pipe 73, and the exhaust pipe 72, and is used for vaporizing the raw fuel. Until the system is sufficiently warmed up, it is desirable to control the system mainly on the partial oxidation reaction that causes an exothermic reaction.
When the system rises to a sufficient temperature and transitions to a steady state in which the reforming reaction can proceed at a sufficient speed, the fuel gas exhaust valve 84 is switched from the open state to the closed state while the fuel gas shutoff valve 82 is Switch from the closed state to the open state. Then, the fuel gas supplied to the fuel cell 23 via the fuel gas introduction pipe 71 is subjected to a cell reaction, and then becomes a hydrogen off-gas and is discharged from the fuel cell 23 via the exhaust pipe 72. This hydrogen off-gas is reused as fuel for generating fuel gas in the evaporator 22a. The oxidizing gas introduced into the oxidizing gas introduction pipe 74 passes through the fuel cell 23, is subjected to a cell reaction, and is discharged from the fuel cell 23 through the exhaust pipe 75.
On the other hand, when the system is stopped, the reformer pressure adjusting valve 81, the fuel gas shutoff valve 82, the hydrogen electrode pressure adjusting valve 83, the fuel gas exhaust valve 84, the oxygen electrode pressure adjusting valve 85, the reforming air shutoff valve 86, By closing various valve mechanisms such as the air cutoff valve 87, the system is made airtight and the fuel gas is prevented from leaking out of the system.
Further, a plurality of pressure sensors 91 to 95 are disposed in various pipes centering on the fuel cell 23 as a fuel gas leak detecting means. The pressure sensor 91 detects the gas pressure of the fuel gas introduction pipe 71 in the pipe section between the reformer 22 and the reformer pressure regulating valve 81. The pressure sensor 92 detects the gas pressure of the fuel gas introduction pipe 71 in a pipe section between the fuel cell 23 and the fuel gas cutoff valve 82. The pressure sensor 93 detects a gas pressure of the exhaust pipe 72 in a pipe section between the fuel cell 23 and the hydrogen electrode pressure regulating valve 83. The pressure sensor 94 detects a gas pressure of the oxidizing gas introduction pipe 74 in a pipe section between the fuel cell 23 and the power generation air compressor 77. The pressure sensor 95 detects the gas pressure of the exhaust pipe 75 in a pipe section between the fuel cell 23 and the oxygen electrode pressure regulating valve 85.
The control unit 24 that controls the fuel cell system 20 is configured as a computer system centered on a microcomputer, and stores various programs (including a fuel gas leak detection processing routine described later) and various data necessary for system control. The stored ROM 25, a CPU 26 that reads a program written in the ROM 25 and appropriately executes the program, a RAM 27 that functions as a work memory of the CPU 26, and inputs detection signals from the above-described pressure sensors 91 to 95. The input / output port 28 that outputs a signal for controlling the opening / closing operation of the valve mechanism and the rotation speed of the combustion air compressor 76 and the power generation air compressor 77, and the gas pressure values detected by the pressure sensors 91 to 95 EEPRO as storage means for writing And (nonvolatile memory) 29, is configured to include a timer 31 serving as a time measuring means for measuring the system downtime. When detecting the leakage of the fuel gas, the control unit 24 activates the alarm means 32 to call the driver's attention. As the warning means 32, a means for audibly calling attention with a warning sound or a sound output, or a means for visually calling attention with a warning lamp, a display, or the like is preferable.
Next, an outline of the fuel gas leak detection process will be described with reference to FIG. FIG. 3 is a graph showing pressure fluctuation characteristics in a piping system centering on the fuel cell 23. It has been confirmed that any of the pressure sensors 91 to 95 exhibits pressure fluctuation similar to the graph shown in FIG. As shown in the figure, during the operation of the system, the gas pressure constantly fluctuates according to the load fluctuation. When an operation stop command is input to the system, the above-described valve mechanism is held in a closed state by a predetermined procedure, and the system transits to a stopped state. Then, the residual gas pressure in the piping system gradually decreases with time. In an abnormal state in which fuel gas is leaking due to damage or deterioration of the piping system of the system or the inside of the fuel cell 23, the pressure drop rate of the residual gas pressure increases. On the other hand, in a normal state in which no damage or the like has occurred in the piping system of the system or the inside of the fuel cell 23 and the fuel gas has not leaked, the pressure drop rate of the residual gas pressure is small.
In consideration of such characteristics, the CPU 26 stores in advance the gas pressure in the piping system at the time of system stop in the EEPROM 29 and measures the gas pressure when the system starts up. By judging whether or not the gas has leaked, it is possible to check whether or not gas has leaked. As a criterion for determining the presence or absence of gas leakage, a threshold value at which the step-down rate decreases with time as shown in FIG. When the CPU 26 determines that the pressure value of the residual gas at the time of starting the system is less than the threshold value, it determines that the system is in an abnormal state and limits the start of the system. On the other hand, if the CPU 26 determines that the pressure value of the residual gas at the time of starting the system is equal to or higher than the threshold value, it determines that the system is in a normal state and permits the system to start. Since the value of the threshold value used as a criterion for determining the presence or absence of gas leakage differs according to the passage of time during which the system has been stopped, the system stop time is written to the EEPROM 29 or the like at the time of the previous system stop, and the time when the system is next started up It is desirable to configure so as to measure the passage of time during the system suspension period.
As shown in FIG. 5, this threshold value may be held as a map value with respect to the passage of time, and further, a parameter (time passage) is substituted into a predetermined formula such as exp (-time passage / time constant). Alternatively, it may be configured to obtain the above. In FIG. 5, the “pressure drop rate” represents {(gas pressure value after elapse of a predetermined time from system stoppage) / (gas pressure value at system stoppage)} × 100 [%], and the residual pressure rate Can also be called. When the pressure drop rate is close to 100%, the gas leakage is small, and the system can be determined to be normal. On the other hand, when the pressure drop rate is close to 0%, the gas leakage is large, and the system can be determined to be abnormal. These map values or calculation formulas for obtaining the threshold value are stored in the ROM 25 in advance. To enhance the accuracy of the system abnormality determination, it is possible to perform temperature compensation on the pressure value of the residual gas. In such a configuration, in addition to the above-described pressure sensors 91 to 95, a temperature sensor for detecting the gas temperature of the piping system may be appropriately provided.
FIG. 6 is a flowchart describing a fuel gas leak detection processing routine executed when the system is started. This routine is read from the ROM 25 when the system is started and is executed by the CPU 26. First, the CPU 26 reads the gas pressure value P1 of the pressure sensor 91 written in the EEPROM 29 at the time of the previous system stop, and acquires the gas pressure value P1 from the pressure sensor 91 at the time of starting the system in order to detect the presence or absence of fuel gas leakage in the reformer 22. The pressure decrease rate (P2 / P1) is calculated by comparing with the pressure value P2 of the residual gas (step S101). Next, the previous system stop time T1 written in the EEPROM 29 is read, and the elapsed time (T2-T1) is obtained by comparing with the current time T2 of the timer 31. After the passage of time is obtained, a threshold is obtained by substituting it into a predetermined formula (step S102). If the pressure decrease rate is less than the threshold value (step S103; YES), it is determined that the fuel gas has leaked to the reformer 22 (step S104), and a warning lamp is turned on to notify the driver. An abnormality is notified to limit system startup (step S105). Here, this routine ends. By restricting the system startup in advance, it is possible to prevent the fuel cell system 20 from burning out.
Here, an example is shown in which the system stop time is written in the EEPROM 29 to measure the elapse of the system stop period. However, the present invention is not limited to this, and the timer 31 is operated even during the system stop. The state may be maintained, and the elapsed time of the system suspension period may be measured.
On the other hand, if the pressure decrease rate is equal to or greater than the threshold value (step S103; NO), the CPU 26 detects the presence or absence of fuel gas leakage in the fuel cell 23, so that the pressure sensor 92 written in the EEPROM 29 at the time of the previous system stoppage is used. Or 93, and reads the gas pressure value P3 of the hydrogen electrode side (P4 / P3) by comparing with the pressure value P4 of the residual gas acquired from the pressure sensor 92 or 93 when the system is started (step S106). ). Next, a threshold value corresponding to the above-mentioned elapsed time (T2-T1) is obtained (step S107). If the pressure drop rate on the hydrogen electrode side is less than the threshold value (step S108; YES), there is a possibility that fuel gas has leaked from the hydrogen electrode side of the fuel cell 23, so the pressure sensor 94 or 95 The detected pressure is compared with the atmospheric pressure (step S109). As will be described later, when the system is stopped, the oxidizing gas introduction pipe 74 and the exhaust pipe 75 are hermetically sealed so that the gas pressure in the pipes becomes approximately the same as the atmospheric pressure. By comparing the pressure with the atmospheric pressure, a gas leak on the oxygen electrode side of the fuel cell 23 can be detected.
If the detected pressure of the pressure sensor 94 or 95 is lower than the atmospheric pressure (step S109; NO), it is determined that the fuel gas leaks only on the hydrogen electrode side (step S110), and the system startup is restricted (step S110). Step S111). If the pressure detected by the pressure sensor 94 or 95 is equal to or higher than the atmospheric pressure (step S109; YES), it is determined that a crossover has occurred due to damage or deterioration of the electrolyte membrane 61 (step S112). The system activation is restricted (step S111). After the processing in step S111, the present routine ends.
On the other hand, if the pressure decrease rate on the hydrogen electrode side of the fuel cell 23 is equal to or higher than the threshold value (step S108; NO), it is considered that no fuel gas leaks from the fuel cell 23, and the system startup is permitted. Then, the process proceeds to a normal operation sequence (step S113). The CPU 26 monitors at regular time intervals whether a system stop command has been input (step S114). If a system stop command cannot be detected (step S114; NO), a loop is formed between step S113 and step S114, and these steps are repeatedly executed.
When the CPU 26 detects the system stop command (Step S114; YES), the CPU 26 arranges the reforming air shut-off valve 86 and the purification air shut-off valve 87 provided on the reformer 22 side and the fuel cell 23 side. The fuel gas cutoff valve 82 and the fuel gas exhaust valve 84 are closed, and the opening degrees of the reformer pressure adjusting valve 81 and the hydrogen electrode pressure adjusting valve 83 are controlled to the fully closed state (step S115). Thereby, the hydrogen electrode side of the fuel cell 23 is maintained in a pressurized state. Next, the power generation air compressor 77 is stopped, and the oxygen electrode pressure regulating valve 85 is controlled to the fully open state to open the oxygen electrode side of the fuel cell 23 (step S116). The gas pressure on the oxygen electrode side of the fuel cell 23 is checked at regular intervals, and if the gas pressure is equal to or higher than the atmospheric pressure (step S117; NO), the oxygen pressure is maintained until the gas pressure becomes approximately equal to the atmospheric pressure. The extreme pressure regulating valve 85 is held in a fully open state (step S117). When the gas pressure on the oxygen electrode side of the fuel cell 23 becomes about atmospheric pressure (step S117; YES), the CPU 26 controls the oxygen electrode pressure regulating valve 85 to a fully closed state (step S118), and the pressure sensors 91 to 91 are controlled. The gas pressure value of 95 and the current time of the timer 31 are written in the EEPROM 29 (step S119), and the system transits to a system stop state (step S120). Here, this routine ends.
When the fuel cell system 20 is used as an on-board generator of the fuel cell vehicle 10, the system operation state and the system stop state are frequently repeated alternately. It is not preferable to stop the vehicle for a long time in view of the use as a vehicle. However, according to the above-described embodiment, the presence / absence of fuel gas leakage can be checked only by checking the gas pressure fluctuation during the system stop period, so that it is suitable for detecting fuel gas leakage of the vehicle-mounted fuel cell system. In particular, it is possible to detect a fuel gas leak only by measuring the pressure drop from the previous stop as an initial check at the start of the system, so that the system configuration can be simplified. However, if the system suspension period is long, even a slight gas leak that is considered normal will cause a significant drop in pressure, making it difficult to detect fuel gas leaks. In such a case, at least the control unit 24 and the pressure sensors 91 to 95 may be operated for a certain period after the system is stopped to perform the fuel gas leak detection process.
FIG. 7 is a flowchart describing a fuel gas leak detection processing routine executed when the system is stopped. This routine is read from the ROM 25 when the system is stopped and executed by the CPU 26. First, the CPU 26 operates in a normal operation sequence (step S201). When the system stop command is detected (Step S202; YES), the shutoff valve 86 for reforming air and the shutoff valve 87 for purification provided on the reformer 22 side and the fuel cell 23 side are provided. The fuel gas cutoff valve 82 and the fuel gas exhaust valve 84 are closed, and the openings of the reformer pressure adjusting valve 81 and the hydrogen electrode pressure adjusting valve 83 are controlled to be fully closed (Step S203). Thereby, the hydrogen electrode side of the fuel cell 23 is maintained in a pressurized state. Next, the power generation air compressor 77 is stopped, and the oxygen electrode pressure regulating valve 85 is controlled to the fully open state to open the oxygen electrode side of the fuel cell 23 (step S204).
The gas pressure on the oxygen electrode side of the fuel cell 23 is checked at regular intervals, and if the gas pressure is equal to or higher than the atmospheric pressure (step S205; NO), the oxygen pressure is maintained until the gas pressure becomes substantially equal to the atmospheric pressure. The extreme pressure regulating valve 85 is held in a fully opened state (step S205). When the gas pressure on the oxygen electrode side of the fuel cell 23 becomes about atmospheric pressure (step S205; YES), the CPU 26 controls the oxygen electrode pressure regulating valve 85 to a fully closed state (step S206), and the pressure sensors 91 to 91 are controlled. The 95 gas pressure value P5 is written into the EEPROM 29 (step S207). Here, most of the system stops operating, but at least the CPU 26 and the pressure sensors 91 to 95 maintain the operating state for a certain period.
When a predetermined period of time has elapsed (step S208; YES), the CPU 26 detects the presence or absence of fuel gas leakage in the reformer 22 so that the gas pressure value P5 of the pressure sensor 91 written in the EEPROM 29 in step S207 is detected. Is read, and the pressure reduction rate (P6 / P5) is calculated by comparing with the current pressure value P6 of the residual gas acquired from the pressure sensor 91 (step S209). Next, a threshold value corresponding to the predetermined period is determined (step S210). If the pressure decrease rate is less than the threshold value (step S211; YES), it is determined that the fuel gas has leaked to the reformer 22 (step S212), and a warning lamp is turned on to notify the driver. An abnormality is notified and the next system startup is restricted (step S213). Here, this routine ends.
On the other hand, if the pressure decrease rate is equal to or greater than the threshold (step S211; NO), the CPU 26 detects the presence or absence of fuel gas leakage in the fuel cell 23, so that the pressure sensor 92 or 93 written in the EEPROM 29 in step S207. The gas pressure value P7 is read, and the pressure drop rate (P8 / P7) on the hydrogen electrode side is calculated by comparing with the current pressure value P8 of the residual gas obtained from the pressure sensor 92 or 93 (step S214). Next, a threshold value corresponding to the predetermined period is determined (step S215). When the pressure drop rate on the hydrogen electrode side of the fuel cell 23 is equal to or higher than the threshold value (step S216; NO), it is considered that no fuel gas leaks to the fuel cell 23, and the system is normally stopped ( Step 217), this routine ends.
On the other hand, if the pressure drop rate on the hydrogen electrode side is less than the threshold value (step S216; YES), there is a possibility that fuel gas has leaked from the hydrogen electrode side of the fuel cell 23, so the pressure sensor 94 or The detected pressure at step 95 is compared with the atmospheric pressure (step S218). If the pressure detected by the pressure sensor 94 or 95 is lower than the atmospheric pressure (step S218; NO), it is determined that a fuel gas leak has occurred on the hydrogen electrode side (step S219), and a warning lamp is turned on. Then, the driver is notified of the abnormality, and the next system activation is restricted (step S220). Here, this routine ends.
If the detected pressure of the pressure sensor 94 or 95 is equal to or higher than the atmospheric pressure (step S218; YES), it is determined that a crossover has occurred due to damage or deterioration of the electrolyte membrane 61 (step S221). The driver is notified of the abnormality by turning on a warning lamp or the like, and the next system activation is restricted (step S220). Here, this routine ends.
As described above, when the system suspension period is long, it is possible to more accurately determine the presence or absence of fuel gas leakage by checking the gas pressure fluctuation after a lapse of a certain period from the system suspension. In addition, since the system is stopped after the fuel gas leak check is performed, if the leak of the fuel gas is detected, the safety of the system can be enhanced by restricting the next start of the system.
In the above description, the pressure drop rate is used to determine the presence or absence of gas leakage. However, the present invention is not limited to this, and the gas pressure in the first and second piping systems when the system is stopped It is also possible to determine the pressure fluctuation amount from the value and the gas pressure value in the same piping system after a lapse of a predetermined time from the stop of the system, and determine the presence or absence of gas leakage from the pressure fluctuation amount. The “pressure fluctuation amount” refers to a value for quantitatively evaluating the fluctuation amount of the gas pressure. For example, the gas pressure value PX of the first and second piping systems when the system is stopped, and a predetermined time after the system is stopped. A value obtained by substituting the gas pressure value PY in the same piping system later into a predetermined function f (PX, PY) can be used as the pressure fluctuation amount.
Here, if f (PX, PY) = PY / PX, the above-described pressure drop rate is obtained. As another specific example of the function f (PX, PY), for example, f (PX, PY) = (PX−PY) / PX, f (PX, PY) = PX−PY, f (PX, PY) = Any function such as PX / PY, f (PX, PY) = PX / (PX-PY), f (PX, PY) = 1 / (PX-PY) can be used. Further, when judging the presence or absence of gas leakage, the above-described threshold is not necessarily required, and the presence or absence of gas leakage may be determined from the value of the function f (PX, PY).
【The invention's effect】
According to the present invention, since leakage of fuel gas can be detected at the time of starting the system, it is suitable for an in-vehicle fuel cell system. Further, even when the system suspension period is long, the leakage of the fuel gas can be detected from the gas pressure change rate after the lapse of a certain period, so that the safety of the system can be improved.
[Brief description of the drawings]
FIG. 1 is a main block diagram of a vehicle equipped with a fuel cell system according to an embodiment.
FIG. 2 is an exploded perspective view of a single cell which is a structural unit of the fuel cell.
FIG. 3 is a system configuration diagram mainly showing a main part of the fuel cell system.
FIG. 4 is a graph showing gas pressure fluctuation characteristics in a piping system centering on a fuel cell.
FIG. 5 is a map value corresponding to a lapse of time of a threshold value for detecting fuel gas leakage.
FIG. 6 is a flowchart of a fuel gas leak detection process executed when the system is started.
FIG. 7 is a flowchart of a fuel gas leak detection process executed when the system is stopped.
[Explanation of symbols]
10. Fuel cell vehicle
20 Fuel cell system
21 ... Tank
22 ... Reformer
22a ... Evaporation section
22b ... reforming section
22c: CO reduction unit
23 ... Fuel cell
24 ... Control unit
25 ... ROM
26 ... CPU
27 ... RAM
28 ... I / O port
29… EEPROM
30 ... secondary battery
31 ... Timer
32 Alarm means
40 ... Power control unit
50 ... motor
60 ... single cell
61 ... Electrolyte membrane
62 ... Anode
62a: porous support layer
62b: hydrogen electrode catalyst layer
63 ... cathode electrode
63a: porous support layer
63b: oxygen electrode catalyst layer
64, 65 ... separator
71 ... Fuel gas inlet pipe
72 ... exhaust pipe
73 ... Bypass piping
74 oxidizing gas introduction pipe
75 ... exhaust pipe
81: Reformer pressure regulating valve
82 ... Fuel gas shutoff valve
83… Hydrogen electrode pressure regulating valve
84 ... fuel gas exhaust valve
85 ... Oxygen pressure control valve
91 to 95 ... Pressure sensor

Claims (18)

A fuel cell that generates power by receiving supply of fuel gas and oxidizing gas, an input path for the fuel gas supplied to the fuel cell, and a first pipe that constitutes an output path for hydrogen off-gas discharged from the fuel cell Strain and
An input path of the oxidizing gas supplied to the fuel cell, and a second piping system constituting an output path of the oxygen off-gas discharged from the fuel cell,
A pressure sensor that detects a gas pressure value of the first piping system, and the second piping system,
The first piping system, and a valve mechanism to shut off the gas flow of the second piping system,
A time lapse measuring means for measuring the time lapse of the system stop state;
Storage means for storing a gas pressure value detected by the pressure sensor,
And a control unit for performing system control,
The control unit controls the valve mechanism when the system is stopped to cut off the gas flow paths of the first piping system and the second piping system, and the gas pressure value detected by the pressure sensor when the system is stopped. Is stored in the storage means,
From the relationship between the gas pressure value detected by the pressure sensor after the elapse of a predetermined time from the system stop, the gas pressure value stored in the storage means, and the elapse of time measured by the time elapse measurement means, the presence or absence of gas leakage is determined. Judgment, fuel cell system. The control unit obtains a pressure fluctuation amount from a gas pressure value detected by the pressure sensor after a predetermined time has elapsed from a system stop, and a gas pressure value stored in the storage unit, and the time variation measurement unit measures the pressure variation. 2. The fuel cell system according to claim 1, wherein the presence or absence of gas leakage is determined based on a relationship between a threshold value serving as a gas leakage determination reference corresponding to a lapse of time and the pressure fluctuation amount. 3. The control unit obtains a pressure fluctuation amount from a gas pressure value detected by the pressure sensor at the time of system startup and a gas pressure value stored in the storage unit, and corresponds to a time lapse measured by the time lapse measurement unit. The fuel cell system according to claim 1, wherein the presence or absence of gas leakage is determined based on a relationship between a threshold value serving as a gas leakage determination reference and the pressure fluctuation amount. A fuel cell that generates power by receiving supply of fuel gas and oxidizing gas, an input path for the fuel gas supplied to the fuel cell, and a first pipe that constitutes an output path for hydrogen off-gas discharged from the fuel cell Strain and
An input path of the oxidizing gas supplied to the fuel cell, and a second piping system constituting an output path of the oxygen off-gas discharged from the fuel cell,
A pressure sensor that detects a gas pressure value of the first piping system, and the second piping system,
The first piping system, and a valve mechanism to shut off the gas flow of the second piping system,
A time lapse measuring means for measuring a time lapse from a time when the system is stopped;
Storage means for storing a gas pressure value detected by the pressure sensor,
And a control unit for performing system control,
The control unit controls the valve mechanism when the system is stopped to cut off the gas flow paths of the first piping system and the second piping system, and the gas pressure value detected by the pressure sensor when the system is stopped. Is stored in the storage means,
Gas leakage is determined from the relationship between the gas pressure value detected by the pressure sensor at the point in time when the time lapse measured by the time lapse measuring means has reached a predetermined time, and the gas pressure value stored in the storage means. Fuel cell system to determine the presence or absence of The control unit, the gas pressure value detected by the pressure sensor at the time when the time elapsed measured by the time elapsed measuring means reaches a predetermined time, and the gas pressure value stored in the storage means 5. The fuel cell system according to claim 4, wherein the pressure fluctuation amount is obtained from the pressure fluctuation amount, and the presence or absence of gas leakage is determined based on a relationship between a threshold value serving as a gas leakage determination reference and the pressure fluctuation amount. 6. The pressure change amount according to claim 1, wherein the pressure fluctuation amount is a ratio between a gas pressure value stored in the storage unit and a gas pressure value detected by the pressure sensor at a point in time when a predetermined time has elapsed since the system was stopped. The fuel cell system according to claim 1. The fuel cell system according to any one of claims 1 to 6, wherein the control unit limits a restart of the system when determining that a gas leak has occurred. The said control part controls the said valve mechanism so that the residual gas pressure of the said 1st piping system may become higher than the residual gas pressure of the said 2nd piping system at the time of a system stop. 8. The fuel cell system according to any one of items 7 to 7. The fuel cell system according to claim 1, wherein the fuel cell system is a power generation system mounted on a vehicle. A fuel cell vehicle comprising the fuel cell system according to any one of claims 1 to 9 as a power generation power source for driving a vehicle. The computer system that controls the fuel cell system
Determining whether a system stop command is input during system operation;
When the system stop command is input,
Controlling a valve mechanism disposed in a first piping system constituting an input path of a fuel gas supplied to the fuel cell and an output path of a hydrogen off-gas discharged from the fuel cell to cut off a gas flow; ,
A step of controlling a valve mechanism disposed in a second piping system constituting an input path of an oxidizing gas supplied to the fuel cell and an output path of an oxygen off-gas discharged from the fuel cell to cut off a gas flow. When,
Storing a gas pressure value in the first piping system and the second piping system at the time of system stop, while executing
Determining whether or not a system start command is input while the system is stopped;
When the system start command is input,
Gas leakage from the relationship between the gas pressure values in the first piping system and the second piping system at the time when the system start command is input, the gas pressure value stored when the system is stopped, and the system stop time Determining the presence or absence of
A computer program that runs The step of judging the presence or absence of the gas leakage includes: a gas pressure value in the first piping system and the second piping system at a time when a system start command is input; and a gas pressure value stored when the system is stopped. 12. The computer program according to claim 11, wherein the computer program according to claim 11, wherein a pressure fluctuation amount is obtained from the above, and the presence or absence of gas leakage is determined from a relationship between a threshold value serving as a gas leakage determination reference corresponding to a system stop time and the pressure fluctuation amount. 13. The computer program according to claim 11, wherein the pressure fluctuation amount is a ratio between a gas pressure value stored when the system is stopped and a gas pressure value at the time when a system start command is input. The computer system that controls the fuel cell system
Determining whether a system stop command is input during system operation;
When the system stop command is input,
Controlling a valve mechanism disposed in a first piping system constituting an input path of a fuel gas supplied to the fuel cell and an output path of a hydrogen off-gas discharged from the fuel cell to cut off a gas flow; ,
A step of controlling a valve mechanism disposed in a second piping system constituting an input path of an oxidizing gas supplied to the fuel cell and an output path of an oxygen off-gas discharged from the fuel cell to cut off a gas flow. When,
Storing a gas pressure value in the first piping system and the second piping system at the time of system stop,
Determining whether a predetermined period of time has elapsed; and
When the certain time has elapsed,
A step of determining the presence or absence of gas leakage from the relationship between the gas pressure value in the first piping system and the second piping system after the fixed time has elapsed, and the gas pressure value stored at the time of stopping the system,
A computer program that runs The step of judging the presence or absence of the gas leakage includes: a gas pressure value in the first piping system and the second piping system at the time when the predetermined time has been reached; and a gas pressure value stored when the system is stopped. 15. The computer program according to claim 14, wherein a pressure fluctuation amount is determined from the above, and the presence or absence of gas leakage is determined based on a relationship between a threshold value serving as a gas leakage determination reference and the pressure fluctuation amount. The computer program according to claim 14, wherein the pressure fluctuation amount is a ratio between a gas pressure value stored when the system is stopped and a gas pressure value at the time when the certain period has elapsed since the system was stopped. 17. The computer system according to claim 11, further comprising the step of, when judging the presence or absence of gas leakage, determining that gas leakage has occurred, causing the computer system to further execute a step of restricting system restart. Computer program according to paragraph. A computer-readable recording medium recording the computer program according to any one of claims 11 to 17.

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