JP2013246984A - Fuel cell system and method for operating the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system that has many opportunities for determining gas leakage in an anode system, and to provide a method for operating the same.SOLUTION: A fuel cell system comprises: a fuel cell stack 10; a fuel gas supply passage through which hydrogen flows; an injector 24 that is provided in the fuel gas supply passage and controls the flow rate of hydrogen; a fuel off-gas discharge passage through which anode off-gas flows; a purge valve 27 that is provided in the fuel off-gas discharge passage and discharges/blocks anode off-gas; load determination means that determines whether or not a load of the fuel cell stack 10 is constant; and gas leakage determination means that determines whether or not gas leaks, on the basis of gas pressure between the injector 24 and the purge valve 27. When a valve-closing command has been issued to the purge valve 27 in a case in which the load determination means determines that the load of the fuel cell stack 10 is constant, the injector 24 makes the flow rate of fuel gas constant, and the gas leakage determination means executes gas leakage determination.

Description

  The present invention relates to a fuel cell system and an operation method thereof.

  As a power source for a fuel cell vehicle or the like, a fuel cell that generates electric power by supplying hydrogen (fuel gas) and oxygen-containing air (oxidant gas) has attracted attention. Then, a method has been proposed in which an injector is provided upstream of the anode, hydrogen is injected by PWM control of the injector corresponding to a load (required power generation amount, etc.), and the flow rate of hydrogen to the fuel cell is controlled ( Patent Document 1).

  In Patent Document 1, whether or not gas is leaking in the anode system including the anode flow path in the fuel cell based on the amount of increase (increase, change) in the anode pressure of the anode system with respect to the operation amount of the injector. Judging.

JP 2007-165237 A

  However, in Patent Document 1, since the gas leak determination is executed only when the anode pressure is increased, for example, when the load is increased, the determination opportunities are reduced.

  Therefore, an object of the present invention is to provide a fuel cell system with many opportunities for determining gas leakage in an anode system and an operation method thereof.

  As means for solving the above-mentioned problems, the present invention provides a fuel cell having a fuel gas flow path, which generates power when fuel gas is supplied to the fuel gas flow path, and an inlet of the fuel gas flow path. A fuel gas supply channel that is connected and through which fuel gas flows toward the fuel gas channel; a fuel gas flow rate control unit that is provided in the fuel gas supply channel and controls the flow rate of the fuel gas; and the fuel gas A fuel off-gas discharge channel connected to an outlet of the channel and through which fuel off-gas from the fuel gas channel flows to the outside; a purge valve provided in the fuel off-gas discharge channel and configured to discharge / shut off the fuel off-gas; Based on the constant determination means for determining whether the load of the fuel cell or the target fuel gas pressure is constant, and the gas pressure between the fuel gas flow control means and the purge valve, gas leaks. Or A gas leakage determination means for determining whether the constant determination means is constant, and when the closing command is input to the purge valve, the fuel gas flow rate control means is configured to control the flow rate of the fuel gas. The fuel cell system is characterized in that the gas leakage determination means executes a gas leakage determination.

  Here, the load of the fuel cell is not only the required power generation amount (required power, target current, etc.) required for the fuel cell, but also the output value (actual power, actual current, etc.) actually output by the fuel cell, It includes parameters that correlate with the load. This parameter includes, for example, measured fuel gas pressure (actually measured anode pressure), accelerator opening when the fuel cell system is mounted on a fuel cell vehicle, and vehicle speed when the battery is not assisting.

  Here, the fuel gas flow rate control means that the flow rate of the fuel gas is constant means that (1) the fuel gas flow rate (supply) is made after the load of the fuel cell is made constant and the fuel gas consumption in the fuel cell is made constant. (2) The fuel gas stoichiometric ratio is constant even if the load of the fuel cell (required power generation amount (required power, target current, etc.) fluctuates) That is, the case where the flow rate of the fuel gas is changed in response to the load change so that the ratio of the flow rate (supply amount) of the fuel gas to the load is constant is included.

  According to such a configuration, the opportunity for the constant determination means to determine that the load of the fuel cell or the target fuel gas pressure is constant is greater than the opportunity to increase the fuel gas pressure (anode pressure) such as when the load increases. Will also increase. That is, in the case of a configuration mounted on a fuel cell vehicle, the load is increased only when the fuel cell vehicle is accelerated, but the load of the fuel cell or the target fuel gas pressure is constant during idling (during idling). ), There are many such as when cruising at a constant speed (during constant speed driving), and opportunities can be easily created by the control method.

Since the valve closing command is normally input to the purge valve, when it is determined that the load of the fuel cell or the target fuel gas pressure is constant, the valve closing command is input to the purge valve. , There are many. Next, in such a case, the fuel gas flow rate control unit makes the flow rate of the fuel gas constant, and the gas leak determination unit executes the gas leak determination. In this way, the chance of gas leak determination in the anode system increases.
Note that when the gas leak determination is performed by the gas leak determination means, the fuel gas flow rate control means keeps the flow rate of the fuel gas constant, so that if there is a gas leak, the gas between the fuel gas flow rate control means and the purge valve The amount of change in pressure increases, and it is possible to determine gas leakage with high accuracy.

  The fuel cell system includes: a storage unit that is parallel to the fuel cell with respect to an external load; and that stores power; and a storage amount detection unit that detects a storage amount of the storage unit; and the constant determination unit Determining whether the load of the fuel cell or the target fuel gas pressure is constant when the electrical storage means assists the required electrical energy from the external load based on the amount of electrical storage of the electrical storage means. preferable.

  According to such a configuration, the constant determination means assists (assists) the required electric energy (total electric energy) from the external load (in the embodiment described later, a motor) based on the amount of power stored in the power storage means. In the case, it is determined whether the load of the fuel cell or the target fuel gas pressure is constant. Therefore, the larger the amount of electricity stored in the electricity storage means, the easier it is to assist (assist) a part of the required electric energy (total electric energy) with the electricity storage means, and there are more opportunities for the load of the fuel cell or the target fuel gas pressure to be constant. Become.

  Further, the assist amount by the power storage means can be varied in accordance with the power storage amount of the power storage means. As a result, the load of the fuel cell (required power, required power generation amount such as target current, output value such as actual power, actual current, target fuel gas pressure, actual fuel gas pressure, etc.) can be varied. Therefore, the amount of assist can be varied to increase the opportunities for the load of the fuel cell or the target fuel gas pressure to be constant.

  The fuel cell system includes vehicle speed detection means that is mounted on a vehicle and detects the vehicle speed of the vehicle, and the constant determination means determines whether the vehicle speed detected by the vehicle speed detection means is a load of the fuel cell or a target fuel gas pressure. A predetermined vehicle speed that is determined to maintain the vehicle running without changing the load of the fuel cell or the target fuel gas pressure after the vehicle speed is below a predetermined vehicle speed corresponding to the lower limit value of the normal range of When it is below, it is preferable to determine that the load of the fuel cell or the target fuel gas pressure is constant.

  According to such a configuration, the vehicle speed detected by the vehicle speed detecting means is not more than a predetermined vehicle speed corresponding to the lower limit value of the load of the fuel cell or the normal range of the target fuel gas pressure, and thereafter the fuel cell When the vehicle speed is equal to or lower than a predetermined vehicle speed at which it is determined that the running of the vehicle is maintained without changing the load or the target fuel gas pressure, the constant determination unit determines that the load of the fuel cell or the target fuel gas pressure is constant. Thus, based on the vehicle speed, it can be determined whether the load of the fuel cell or the target fuel gas pressure is constant, and if it is constant, the gas leak determination can be executed.

  The vehicle speed detecting means for detecting the vehicle speed is not only a vehicle speed sensor that directly detects the vehicle speed based on the rotational speed of the wheel, but also the vehicle speed based on the vehicle position information from a navigation device, GPS, or the like. A means for calculating indirectly is also included. That is, based on the vehicle speed from the vehicle speed sensor and the vehicle speed calculated based on the position information of the vehicle from the navigation device or GPS, it can be determined with high accuracy whether or not the constant determination means is constant.

  In the fuel cell system, the power control means includes: power storage means for storing power of the fuel cell; and power control means for controlling power generation of the fuel cell and controlling power storage in the power storage means. When the fuel cell is generated with constant power and the constant power of the fuel cell is stored in the power storage means, the constant determination means has a constant load or target fuel gas pressure of the fuel cell. Is preferably determined.

  According to such a configuration, when the power control means generates the fuel cell with constant power and stores the constant power of the fuel cell in the power storage means, the constant determination means determines whether the fuel cell load or target It is determined that the fuel gas pressure is constant. In this way, it is possible to determine whether the load of the fuel cell or the target fuel gas pressure is constant based on the power generation state of the fuel cell and the power storage state of the power storage means. Can be executed.

  In the fuel cell system, it is preferable that the fuel gas flow rate control unit sets the flow rate of the fuel gas as a gas leak determination flow rate when the gas leak determination unit performs the gas leak determination.

  According to such a configuration, when the gas leak determination unit performs the gas leak determination, the fuel gas flow rate control unit sets the flow rate of the fuel gas as the gas leak determination flow rate. That is, when the gas leak determination is performed, the flow rate of the fuel gas becomes a predetermined gas leak determination flow rate.

  As a result, the gas pressure between the fuel gas flow rate control means and the purge valve is substantially constant when the gas is not leaking, or changes corresponding to the consumption of the fuel gas by the fuel cell. On the other hand, when the gas is leaking, the gas pressure is not substantially constant or does not change corresponding to the consumption of the fuel gas. Therefore, a value obtained in advance by a preliminary test or a simulation can be used as a gas leak determination threshold value that is a criterion for determining whether or not gas is leaking. Therefore, the gas leak determination process becomes simple.

  In the fuel cell system, it is preferable that the gas leak determination flow rate is set based on a fuel gas consumption amount consumed by the fuel cell that generates power.

  According to such a configuration, since the gas leak determination flow rate is set based on the fuel gas consumption amount consumed by the fuel cell, the change in the gas pressure between the fuel gas flow rate control means and the purge valve Tends to depend on the presence or absence of gas leakage. Thereby, gas leak determination can be performed satisfactorily.

  In the fuel cell system, the gas leak determination flow rate includes: a fuel gas consumption amount consumed by the fuel cell to generate power; and a fuel gas leak amount leaking from the fuel gas flow channel of the fuel cell to the oxidant gas flow channel. Are preferably set based on the above.

  According to such a configuration, the flow rate for gas leak determination includes the fuel gas consumption amount consumed by the fuel cell and the fuel gas leak amount (cross leak amount) leaking from the fuel gas flow channel of the fuel cell to the oxidant gas flow channel. Therefore, the change in the gas pressure between the fuel gas flow rate control means and the purge valve tends to depend on the presence or absence of gas leakage. Thereby, gas leak determination can be performed satisfactorily.

  Here, the fuel gas leak amount means the amount (cross leak amount) that the fuel gas permeates through the electrolyte membrane constituting the fuel cell while being in a gas state. The amount of fuel gas leak includes the state of the electrolyte membrane constituting the fuel cell (temperature, water content, usage time (cumulative power generation amount), etc.), fuel gas state of the fuel gas flow path (fuel gas pressure, fuel gas concentration, etc.) Therefore, it is preferable to correct based on the state of the electrolyte membrane and the fuel gas state of the fuel gas flow path.

  For example, since the temperature of the electrolyte membrane is substantially the same as the temperature of the fuel cell, the temperature of the electrolyte membrane is detected via the temperature of the gas or refrigerant discharged from the fuel cell. As the temperature of the electrolyte membrane increases, the moisture content increases as the moisture content increases, and as the usage time (cumulative power generation amount) increases, the fuel gas (hydrogen gas or the like) becomes more easily permeable. It becomes a trend.

  In the fuel cell system, the fuel off-gas discharge channel upstream of the purge valve is connected to the fuel gas supply channel downstream of the fuel gas flow rate control means, and fuel off-gas containing fuel gas is discharged from the fuel off-gas. The fuel gas is circulated through the fuel gas passage and the fuel gas circulation passage by operating the fuel gas circulation passage for returning the fuel gas from the passage to the fuel gas supply passage and circulating the fuel gas. A fuel gas circulation pump, and the fuel gas circulation pump increases the amount of gas circulation with respect to the normal time when the gas leak judgment is performed by the gas leak judgment means and when the gas leak judgment is not performed. It is preferable to do.

  According to such a configuration, when the gas leak determination is performed, the fuel gas flow rate control unit makes the flow rate of the fuel gas immediately downstream thereof constant, and the fuel gas circulation pump increases the gas circulation rate relative to the normal time. Therefore, it becomes difficult for the fuel cell to become short of fuel gas.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel cell system with many opportunities of the gas leak determination in an anode system, and its operating method can be provided.

1 is a configuration diagram of a fuel cell system according to a first embodiment. FIG. It is a flowchart which shows operation | movement of the fuel cell system which concerns on 1st Embodiment. It is a time chart which shows the operation example of the fuel cell system which concerns on 1st Embodiment. It is a flowchart which shows operation | movement of the fuel cell system which concerns on 2nd Embodiment. It is a time chart which shows one operation example of the fuel cell system concerning a 2nd embodiment.

<< First Embodiment >>
A first embodiment of the present invention will be described with reference to FIGS.

≪Configuration of fuel cell system≫
A fuel cell system 1 shown in FIG. 1 is mounted on a fuel cell vehicle (vehicle, moving body) (not shown). The fuel cell vehicle is, for example, an automobile, a tricycle, a motorcycle, a unicycle, a train, or the like. However, the structure mounted in the other mobile body, for example, a ship, an aircraft, may be sufficient.

  The fuel cell system 1 includes a fuel cell stack 10, a cell voltage monitor 15, an anode system that supplies and discharges hydrogen (fuel gas and reactive gas) to and from the anode of the fuel cell stack 10, and a cathode of the fuel cell stack 10. In contrast, a cathode system that supplies and discharges air containing oxygen (oxidant gas and reaction gas), a power control system that controls power generation of the fuel cell stack 10, and an ECU 70 (Electronic Control Unit, electronic control device) that electronically controls these systems ) And.

<Fuel cell stack>
The fuel cell stack 10 is a stack formed by stacking a plurality of (for example, 200 to 400) solid polymer type single cells 11, and the plurality of single cells 11 are electrically connected in series. The single cell 11 includes an MEA (Membrane Electrode Assembly) and two conductive separators sandwiching the MEA. The MEA includes an electrolyte membrane (solid polymer membrane) made of a monovalent cation exchange membrane or the like, and an anode and a cathode (electrode) that sandwich the membrane.

  The anode and the cathode include a porous body having conductivity such as carbon paper, and a catalyst (Pt, Ru, etc.) supported on the anode and causing an electrode reaction in the anode and the cathode.

  Each separator is formed with a groove for supplying hydrogen or air to the entire surface of each MEA, and through holes for supplying and discharging hydrogen or air to all single cells. It functions as a passage 12 (fuel gas passage) and a cathode passage 13 (oxidant gas passage).

  When hydrogen is supplied to each anode via the anode flow path 12, the electrode reaction of Formula (1) occurs, and when air is supplied to each cathode via the cathode flow path 13, Formula (2) Thus, a potential difference (OCV (Open Circuit Voltage), open circuit voltage) is generated in each single cell. Next, when the fuel cell stack 10 and an external circuit such as the motor 51 are electrically connected and a current is taken out, the fuel cell stack 10 generates power.

2H ₂ → 4H ⁺ + 4e ⁻ (1)
O ₂ + 4H ++ 4e ⁻ → 2H ₂ O (2)

<Cell voltage monitor>
The cell voltage monitor 15 is a device that detects a cell voltage for each of the plurality of single cells 11 constituting the fuel cell stack 10, and includes a monitor main body and a wire harness that connects the monitor main body and each single cell. .

  The monitor body scans all the single cells 11 at a predetermined period, detects the cell voltage of each single cell 11, and calculates the average cell voltage and the lowest cell voltage. The monitor main body (cell voltage monitor 15) outputs an average cell voltage and a minimum cell voltage to the ECU 70.

<Anode system>
The anode system includes a hydrogen tank 21 (fuel gas supply source), a normally closed shut-off valve 22, a mechanical first regulator 23, an injector 24, an ejector 25, and a purge valve 27. .

  The hydrogen tank 21 is connected to the inlet of the anode flow path 12 through a pipe 21a, a shutoff valve 22, a pipe 22a, a first regulator 23, a pipe 23a, an injector 24, a pipe 24a, an ejector 25, and a pipe 25a. When the injector 24 injects hydrogen with the shut-off valve 22 open, the hydrogen in the hydrogen tank 21 is supplied to the anode flow path 12 through the pipe 21a and the like.

  Here, the fuel gas supply channel that is connected to the inlet of the anode channel 12 and through which hydrogen supplied to the anode channel 12 flows is a pipe 21a, a pipe 22a, a pipe 23a, a pipe 24a, and a pipe. 25a. An injector 24 is provided in the fuel gas supply channel.

  The hydrogen tank 21 is a container in which hydrogen is stored at a high pressure.

  The shutoff valve 22 is a normally closed electromagnetic valve, and is a valve that supplies / shuts off hydrogen by opening / closing in accordance with a command from the ECU 70.

  The first regulator 23 is a mechanical pressure reducing valve that reduces the pressure (high pressure) of hydrogen from the hydrogen tank 21 to a predetermined medium pressure.

  The injector 24 is an injection device that injects hydrogen intermittently (intermittently) by being electronically controlled by the ECU 70. Therefore, the fuel gas supply means for supplying the fuel gas corresponding to the target current (required power generation amount) includes the injector 24 and the ECU 70 that controls the injector 24. The injector 24, the shutoff valve 22, the compressor 41 described later, and the like are powered by the fuel cell stack 10 and / or the battery 55 described later.

  The injector 24 also has a function as pressure regulating means (second regulator) for adjusting the secondary side pressure by repeatedly injecting / stopping hydrogen.

  The ejector 25 mixes the nozzle 25b that generates negative pressure by injecting new hydrogen from the injector 24, and the anode off-gas of the pipe 26b (fuel off-gas circulation passage) sucked at the negative pressure. , And a diffuser 25c that supplies the pipe 25a (the anode flow path 12).

  The outlet of the anode channel 12 is connected to the intake port of the ejector 25 via a pipe 26a, a check valve 26, and a pipe 26b. Then, anode offgas (fuel offgas) containing unconsumed hydrogen discharged from the anode channel 12 is returned to the ejector 25 (fuel gas supply channel). Therefore, the fuel gas circulation flow path for circulating hydrogen by returning the anode off-gas discharged from the anode flow path 12 to the ejector 25 includes the pipe 26a and the pipe 26b.

  The check valve 26 is a valve that prevents the backflow of the anode off gas. The pipe 26a is provided with a gas-liquid separator (not shown) that separates liquid water accompanying the anode off gas.

  The middle of the pipe 26a is connected to a diluter 44 described later via a pipe 27a, a purge valve 27, and a pipe 27b. That is, the fuel off-gas discharge passage through which the anode off-gas that flows from the anode passage 12 toward the outside of the vehicle (external) flows includes a part of the pipe 26a, the pipe 27a, the pipe 27b, and the pipe 44a. A purge valve 27 is provided in the fuel off-gas discharge passage. The purge valve 27 is a normally closed electromagnetic valve that discharges / blocks the anode off gas by opening / closing.

  Specifically, the purge valve 27 discharges (purges) impurities (water vapor, nitrogen, etc.) contained in the anode off-gas circulating through the pipe 26a during power generation of the fuel cell stack 10, or when the system is started up. When replacing 12 with hydrogen, it is opened by the ECU 70. Note that the ECU 70 opens the purge valve 27 when, for example, the lowest cell voltage detected via the cell voltage monitor 15 is equal to or lower than a predetermined voltage at which impurities are to be discharged.

  The middle of the pipe 26a is connected to the pipe 25a via the pipe 28a, the hydrogen circulation pump 28, and the pipe 28b. The hydrogen circulation pump 28 is driven to generate a gas flow in a circulation circuit constituted by the pipe 28b, the pipe 25a, the anode flow path 12, the pipe 26a, and the pipe 28a, and prevent flooding in the anode.

  The pressure sensor 31 is attached to a pipe 25 a downstream of the injector 24 and upstream of the anode flow path 12. The pressure sensor 31 detects the pressure (measured anode pressure P2) in the pipe 25a and outputs it to the ECU 70.

  The pressure sensor 32 is attached to the pipe 26 a downstream of the anode flow path 12. The pressure sensor 32 detects the pressure (measured anode pressure P3) in the pipe 26a and outputs the detected pressure to the ECU 70.

  The pressure sensor 33 is attached to the pipe 23 a upstream of the injector 24. And the pressure sensor 33 detects the pressure in the piping 23a, and outputs it to ECU70.

<Cathode system>
The cathode system includes a compressor 41, a humidifier 42, a normally open back pressure valve 43, a diluter 44, and a normally closed air bypass valve 45.
The discharge port of the compressor 41 is connected to the inlet of the cathode channel 13 via a pipe 41a, a humidifier 42, and a pipe 42a. When the compressor 41 operates in accordance with a command from the ECU 70, it takes in oxygen-containing air and supplies it to the cathode flow path 13 through the piping 41a and the like.

  The humidifier 42 includes a hollow fiber membrane 42d that is permeable to moisture. Then, the humidifier 42 exchanges moisture between the new air heading toward the cathode flow path 13 and the humid cathode offgas via the hollow fiber membrane 42d to humidify the new air.

  A pipe 42b, a humidifier 42, a pipe 43a, a back pressure valve 43, a pipe 43b, a diluter 44, and a pipe 44a are connected to the outlet of the cathode channel 13 in this order. And the cathode off gas from the cathode flow path 13 is discharged | emitted out of a vehicle through piping 42b etc. As shown in FIG.

  The back pressure valve 43 is constituted by a butterfly valve, for example. And the back pressure (pressure of the cathode flow path 13) is controlled by controlling the opening degree of the back pressure valve 43 in accordance with a command of the ECU 70.

  The diluter 44 is a container that mixes the anode off-gas and the cathode off-gas and dilutes the hydrogen in the anode off-gas with the cathode off-gas (dilution gas), and has a dilution space therein.

  The middle of the pipe 41a is connected to the pipe 43b through the pipe 45a, the air bypass valve 45, and the pipe 45b. When the air bypass valve 45 is opened by the ECU 70, the air from the compressor 41 passes through the pipe 45a or the like, that is, bypasses the humidifier 42 and the fuel cell stack 10, and flows into the pipe 43b. Yes.

<Power control system>
The power control system includes a motor 51 (external load), a PDU 52 (Power Drive Unit), a power controller 53, an output detector 54, a battery 55 (power storage means), and an SOC sensor 56 (special electric energy detection means). And. The motor 51 is connected to an output terminal (not shown) of the fuel cell stack 10 via the PDU 52, the power controller 53, and the output detector 54, and the battery 55 is connected to the power controller 53. That is, the battery 55 and the fuel cell stack 10 are electrically connected to the motor 51 in parallel.

  The motor 51 is an electric motor that generates a driving force for running the fuel cell vehicle.

  The PDU 52 is an inverter that converts DC power from the power controller 53 into three-phase AC power and supplies it to the motor 51 in accordance with a command from the ECU 70.

  The power controller 53 follows (1) a function of controlling the output (generated power, current value, voltage value) of the fuel cell stack 10 including a certain value and (2) charging / discharging of the battery 55 in accordance with a command from the ECU 70. And a function to control. Such a power controller 53 includes various electronic circuits such as a DC-DC chopper circuit.

  The output detector 54 is a device that detects an actual output (measured current value, measured voltage value) that is a load of the fuel cell stack 10, and includes a current sensor and a voltage sensor. The output detector 54 outputs the detected actual measurement current value and actual measurement voltage value to the ECU 70.

  The battery 55 is a power storage device that charges (accumulates) / discharges electric power, and includes, for example, an assembled battery formed by combining a plurality of lithium ion type cells.

  The SOC sensor 56 detects the SOC (State Of Charge, charge amount (%), charged amount) of the battery 55 and outputs it to the ECU 70.

<Other equipment>
The IG 61 is a start switch of the fuel cell system 1 (fuel cell vehicle), and is provided around the driver's seat. The IG 61 is connected to the ECU 70, and the ECU 70 detects an ON signal (system start signal) and an OFF signal (system stop signal) of the IG 61.

  The accelerator opening sensor 62 is a sensor that detects an accelerator opening that is a depression amount of an accelerator pedal (not shown). The accelerator opening sensor 62 outputs the accelerator opening to the ECU 70.

  The warning lamp 63 is a lamp for informing the driver of gas leakage, and is provided around the driver's seat.

<ECU>
The ECU 70 is a control device that electronically controls the fuel cell system 1 and includes a CPU, ROM, RAM, various interfaces, electronic circuits, and the like, and controls various devices according to programs stored therein. However, various processes are executed.

<ECU-Injector Control (Fuel Gas Supply) Function>
The ECU 70 (control means) has a function of opening and closing the injector 24 (PWM control) and supplying hydrogen toward the anode flow path 12 corresponding to the target current (required power and required power generation amount). That is, the ECU 70 has a function of changing the ratio (duty ratio) between the opening time and the closing time of the injector 24 and changing the amount of hydrogen injected by the injector 24 including zero.

  As a result, the flow rate (L / min) of hydrogen flowing through the anode flow path 12 is varied including zero. In addition, by varying the amount of hydrogen injected by the injector 24 in this way, the secondary pressure, that is, the gas (hydrogen) in the flow path including the anode flow path 12 and between the injector 24 and the purge valve 27 is included. Pressure) is controlled (adjusted).

  Note that the flow rate of hydrogen injected by the injector 24 is calculated based on the differential pressure across the injector 24 and the opening time. The differential pressure across the injector 24 is given by the difference between the pressure detected by the pressure sensor 33 and the measured anode pressure P2 detected by the pressure sensor 31. The ECU 70 stores in advance a map in which the differential pressure across the injector 24, the opening time, and the injection amount are associated with each other, and the ECU 70 controls the injector 24 with reference to this map. ing.

<ECU-fixed determination function>
The ECU 70 (constant determination means) has a function of determining whether or not the load (including the actual measurement value and the target value) of the fuel cell stack 10 and the target anode pressure P1 (target fuel gas pressure) are constant.

  Here, the measured current value and / or target current value of the fuel cell stack 10, the target anode pressure P 1 and / or measured anode pressure P 2 of the gas (hydrogen) flowing through the anode flow path 12, and the rotational speed of the compressor 41. And / or the pressure of the gas (air) flowing through the cathode flow path 13, the accelerator opening, and the vehicle speed have a correlation. That is, as the load increases, the measured current value and / or target current value increases, the target anode pressure P1 and / or measured anode pressure P2 of the gas (hydrogen, air), and the rotational speed of the compressor 41 increase. The accelerator opening increases and the vehicle speed increases.

  The present embodiment exemplifies a configuration in which it is determined that the load of the fuel cell stack 10 is constant when the pressure change amount ΔP1 of the target anode pressure P1 at the predetermined time Δt1 is equal to or less than a predetermined value (predetermined change amount). However (see FIG. 3), the determination may be made based on other parameters (measured current value, target current value, measured anode pressure P2, rotational speed of the compressor 41, accelerator opening, vehicle speed, etc.).

<ECU-Gas leak judgment function>
The ECU 70 (gas leakage determination means) has a function of determining whether or not anode leakage has occurred. Anode leakage means that gas that should remain between the anode injector 24 and the purge valve 27 is leaking to the outside. In addition, when the purge valve 27 fails to open (not close normally) between the injector 24 and the purge valve 27, or the sealing performance of the piping, the fuel cell stack 10, and various valves constituting the anode system decreases. Anode leakage occurs.

  Specifically, the ECU 70 determines the gas based on the change Δt2 that is the difference between the initial value (t0) of the actually measured anode pressure P2 detected via the pressure sensor 31 and the current value, and the gas leak determination threshold ΔP5. It is determined whether or not there is a leak. A specific determination method will be described later.

  In addition to or instead of this, the anode leakage may be provided based on the measured anode pressure P3 that is provided downstream of the anode flow path 12 and detected by the pressure sensor 32 that is closer to the purge valve 27 than the pressure sensor 31. Good. With such a configuration, if the purge valve 27 has an open failure, the actual measurement anode pressure P3 detected by the pressure sensor 32 decreases more quickly than the actual measurement anode pressure P2, so that the predetermined time Δt2 can be shortened.

≪Operation and effect of fuel cell system≫
Next, the operation and effect of the fuel cell system 1 will be described with reference mainly to FIG.

  In the operation method of the fuel cell system 1 according to the first embodiment, the pressure change for determining whether or not the target pressure (target anode pressure P1, target fuel gas pressure) in the anode flow path 12 of the fuel cell stack 10 is constant. In the determination step (S103, constant determination step) and the pressure change determination step, the target pressure (target anode pressure P1) in the anode flow path 12 of the fuel cell stack 10 is determined to be constant (Yes in S103). When the valve closing command is input to the purge valve 27 (S102, No), the flow rate of hydrogen is controlled by the injector 24 (fuel gas flow rate control means) while keeping the measured current (load) of the fuel cell stack 10 constant. Based on the measured anode pressure P2 detected by the pressure sensor 31 between the injector 24 and the purge valve 27, Scan included in the determining whether gas leakage judgment step is leaking (S108), the.

  That is, here, a configuration in which it is determined whether or not gas is leaking in a state where the measured current (load) and the hydrogen flow rate of the fuel cell stack 10 are constant and the hydrogen stoichiometric ratio is constant is illustrated. However, for example, the measured current (target current, load) of the fuel cell stack 10 is changed corresponding to the accelerator opening, and the measured current (target current) of the fuel cell stack 10 is kept constant while maintaining the hydrogen stoichiometric ratio. It is also possible to determine whether or not gas is leaking in a state where the flow rate of hydrogen is changed in response to the load. In this configuration, when no gas leaks, the measured anode pressure P2 detected by the pressure sensor 31 is constant.

  As an initial state, the IG 61 is turned on, hydrogen and air are supplied to the fuel cell stack 10, and the fuel cell stack 10 is generating electric power. The fuel cell system 1 is also operated in the same manner as in the initial state in step S121 described later.

  Specifically, the ECU 70 calculates a target current (required electric energy) to be output to the fuel cell stack 10 based on the accelerator opening. The target current increases as the accelerator opening increases. Note that the target current is a command current that the ECU 70 commands the power controller 53. Here, a case where the battery 55 does not assist the fuel cell stack 10 is illustrated.

The anode side control will be described.
Based on the target current, the ECU 70 calculates a target hydrogen flow rate Q to be passed toward the anode flow path 12 and a target anode pressure P1 to be targeted in the anode flow path 12. As the target current increases, the target hydrogen flow rate Q increases and the target anode pressure P1 increases.

  The ECU 70 performs open / close control (PWM control) of the injector 24 so that the target hydrogen flow rate Q and the target anode pressure P1 are obtained. That is, the ECU 70 controls the injector 24 so that the open time (ON duty) becomes longer as the target hydrogen flow rate Q and the target anode pressure P1 increase.

More specifically, the target hydrogen flow rate Q is calculated according to the equation (3), for example.
Target hydrogen flow rate Q = basic hydrogen flow rate Q10 + feedback amount Q20 (3)

  The feedback amount Q20 is a hydrogen amount to be corrected in the PID control, and is calculated based on a difference between the target anode pressure and the actually measured anode pressure P2 detected by the pressure sensor 31. For example, when the measured anode pressure P2 is lower than the target anode pressure P1, the feedback amount Q20 is calculated on the plus side (increase side), and when the measured anode pressure P2 is higher than the target anode pressure P1, the feedback amount Q20 is minus side. (Decrease side)

  The basic hydrogen flow rate Q10 is given by Expression (4) when the target anode pressure P1 is constant with respect to the calculated value of the previous cycle, and is given by Expression (5) when the target anode pressure P1 is increasing. When the target anode pressure P1 is reduced, it is given by equation (6).

Basic hydrogen flow rate Q10 = current hydrogen flow rate Q11 + pressure maintaining hydrogen flow rate Q12 (4)
Basic hydrogen flow rate Q10 = current hydrogen flow rate Q11 + hydrogen flow rate Q13 for pressure increase (5)
Basic hydrogen flow rate Q10 = Current hydrogen flow rate Q11 (6)

  The current hydrogen flow rate Q11 is calculated based on the amount of hydrogen consumed by the fuel cell stack 10 when the fuel cell stack 10 generates power at the target current described above. As the target current increases, the hydrogen consumption and the current hydrogen flow rate Q11 increase.

  The pressure maintaining hydrogen flow rate Q12 is a hydrogen flow rate necessary for maintaining a constant pressure between the injector 24 and the purge valve 27. For example, when the total operation time of the fuel cell system 1 is increased, the sealing performance of the sealing material (O-ring or the like) for preventing gas leakage is deteriorated. Therefore, as the total operation time is increased, the pressure maintaining hydrogen flow rate Q12 is It is a growing relationship.

  The pressure increasing hydrogen flow rate Q13 is a hydrogen flow rate necessary for increasing the target anode pressure P1 between the injector 24 and the purge valve 27. The relationship is such that the pressure increase hydrogen flow rate Q13 increases as the degree of pressure increase (increase rate) increases.

When executing a series of gas leak determination processes (S104 to S107) described later, the ECU 70 is set to calculate the target hydrogen flow rate Q according to the equation (7) without executing the feedback control. This is because when the anode leakage is present when the feedback control is executed, the hydrogen flow rate increases, and the measured anode pressure P2 becomes difficult to decrease, making it difficult to determine the gas leakage.
Target hydrogen flow rate Q = Basic hydrogen flow rate Q10 (7)

The cathode side control will be described.
Based on the target current, the ECU 70 calculates a target air flow rate to be passed toward the cathode flow path 13 and a target cathode pressure to be targeted in the cathode flow path 13. The ECU 70 controls the rotational speed of the compressor 41 and the opening of the back pressure valve 43 based on the target air flow rate and the target cathode pressure. As the target air flow rate increases, the rotational speed of the compressor 41 increases and the opening degree of the back pressure valve 43 decreases as the target cathode pressure increases.

Each process of the flowchart shown in FIG. 2 will be specifically described.
In step S101, the ECU 70 determines whether or not to execute anode (gas) leakage determination. The anode leak determination is a series of determination processes (S104 to S107) relating to whether or not a gas leak has occurred between the anode injector 24 and the purge valve 27.

  Specifically, for example, the ECU 70 performs a purge after a predetermined time (for example, 10 minutes to 60 minutes) has elapsed from a series of processing (S103 · Yes to S107 · No) related to the previous anode leakage determination, or after the IG 61 is turned on. When the operation state of the system is a predetermined operation state that the leak determination is necessary, such as after the purge is performed by opening and closing the valve 27, it is determined that the anode leakage determination is performed.

  When it is determined that the anode leakage determination is to be executed (S101 / Yes), the process of the ECU 70 proceeds to step S102. When it is determined not to execute the anode leakage determination (No in S101), the process of the ECU 70 proceeds to step S121.

  In step S102, the ECU 70 determines whether or not the purge is being performed, that is, whether or not the purge valve 27 is being opened. The purge valve 27 discharges impurities such as water vapor when the minimum cell voltage input from the cell voltage monitor 15 is equal to or lower than a predetermined cell voltage or every set time corresponding to the operating state such as a load. Is opened intermittently.

  If it is determined that the purge is being performed (S102: Yes), the process of the ECU 70 proceeds to step S121. When it determines with not purging (S102 * No), the process of ECU70 progresses to step S103.

  Note that the order of step S102 and step S103 may be reversed. Further, the measured anode pressure P2 may not be stable immediately after the purge valve 27 is closed. Therefore, when a predetermined time has elapsed since the purge valve 27 is closed, it is determined that the measured anode pressure P2 is stable. The process may proceed to step S103.

  In step S103, the ECU 70 determines whether or not the pressure change amount ΔP1 of the target anode pressure P1 is equal to or less than a predetermined value at a predetermined time Δt1 immediately before the current time.

  When it is determined that the pressure change amount ΔP1 is equal to or less than the predetermined value (S103 / Yes), the process of the ECU 70 proceeds to step S104. When the process proceeds to step S104 as described above, the ECU 70 determines that the pressure in the anode flow path 12 of the fuel cell stack 10 is constant, and starts the gas leak determination mode for executing the anode leak determination, that is, the current anode A series of processing (S104 to S107) related to leakage determination is started.

  If it is determined that the pressure change amount ΔP1 is not less than or equal to the predetermined value (S103, No), the process of the ECU 70 proceeds to step S121.

In step S104, the ECU 70 makes the target current (command current to the power controller 53) to be output to the fuel cell stack 10 constant. Note that the constant target current value (target current value) is, for example, the target current (command current) at the time of proceeding to step S104. Thereby, after that, the consumption ratio of hydrogen consumed by the fuel cell stack 10 to generate electricity becomes constant, and the gas leak determination becomes easy.
In addition, for example, the target current (command current) may be constant after being changed to be higher or lower.

  In step S104, the ECU 70 continuously outputs a valve closing command to the purge valve 27, and prohibits purging.

  In step S105, the ECU 70 stores the measured anode pressure P2 (t0) detected via the pressure sensor 31 as an initial value (see FIG. 3).

  In step S106, the ECU 70 controls the injector 24 to change the flow rate of injected hydrogen to a hydrogen flow rate Q1 for determining node leakage different from the normal time, and keep it constant (see FIG. 3).

  The hydrogen flow rate Q1 for determining anode leakage is calculated based on the above-described equation (7), for example. That is, the hydrogen flow rate Q1 for determining anode leakage is changed to a small flow rate because the feedback amount Q20 in the equation (3) is not taken into consideration (see FIG. 3).

  In this case, the hydrogen flow rate Q1 for determining anode leakage is preferably set to a flow rate corresponding only to the hydrogen consumption amount consumed by the fuel cell stack 10 that generates power at a constant target current. In this way, the amount of change ΔP2 of the subsequent measured anode pressure P2 changes corresponding to only the presence or absence of gas leakage, and a gas leakage determination can be made satisfactorily. In addition, the gas leak determination threshold value ΔP5 that serves as a reference for the gas leak determination can be constant during the gas leak determination. The gas leak determination threshold value ΔP5 is obtained by a preliminary test or the like and stored in the ECU 70 in advance.

  Further, the hydrogen flow rate Q1 for anode leakage determination is consumed by the fuel cell stack 10 that generates power at a constant target current, and the hydrogen that cross leaks from the anode channel 12 to the cathode channel 13 during the gas leakage determination. It is good also as a structure set based on the amount of cross leaks (fuel gas cross leak amount). In this way, the amount of change ΔP2 of the actually measured anode pressure P2 changes with high accuracy only in correspondence with the presence or absence of gas leakage, and a gas leakage determination can be made better.

  For example, as the temperature of the electrolyte membrane increases, the amount of hydrogen cross leak increases as the water content of the electrolyte membrane increases. Therefore, the hydrogen cross leak is determined based on the temperature of the fuel cell stack 10 at the time of gas leak determination. It is preferred to calculate the amount. Here, the temperature of the fuel cell stack 10 is estimated, for example, via the temperature of the cooling refrigerant discharged from the fuel cell stack 10.

  In step S107, after step S106 (after the start of the gas leakage determination mode), the ECU 70 obtains a change amount ΔP2 that is a difference between the initial measured anode pressure P2 (t0) and the current measured anode pressure P2 (current). It is determined whether or not the gas leak determination threshold value ΔP5 or more has continued for a predetermined time Δt2 or more (see FIG. 3).

  Here, since the hydrogen flow rate Q1 and the target current are made constant, the measured anode pressure P2 becomes substantially constant when no gas leaks between the injector 24 and the purge valve 27. The change amount ΔP2 is a change amount that is not assumed when the gas is normal without leaking, and the predetermined time Δt2 is a failure determination time set to prevent erroneous detection due to an unexpected pressure fluctuation error. The change amount ΔP2 and the predetermined time Δt2 are obtained by a preliminary test or the like and stored in the ECU 70 in advance.

  When it is determined that the state where the change amount ΔP2 is greater than or equal to the gas leakage determination threshold ΔP5 has continued for the predetermined time Δt2 or longer (S107: Yes), the processing of the ECU 70 proceeds to step S108. When the process proceeds to step S108 in this way, for example, the purge valve 27 is not normally closed and has an open failure, and the gas containing hydrogen that should remain between the injector 24 and the purge valve 27 passes through the purge valve 27. This is a case where it is determined that there is a possibility that anode leakage may occur due to outflowing downstream or deterioration of the sealing performance of the piping, fuel cell stack 10 and various valves constituting the anode system.

  When it is determined that the state where the change amount ΔP2 is greater than or equal to the gas leakage determination threshold ΔP5 has not continued for the predetermined time Δt2 or longer (S107, No), the processing of the ECU 70 proceeds to step S121. In this way, the process proceeds to step S121 when it is determined that no anode leakage has occurred.

  In step S108, the ECU 70 turns on the warning lamp 63 to notify the driver that hydrogen is leaking (there is an anode leak).

  In step S109, the ECU 70 opens the air bypass valve 45. Thereby, the air from the compressor 41 passes through the piping 45a and the piping 45b, bypasses the humidifier 42 and the cathode flow path 13 (fuel cell stack 10), and flows into the piping 43b.

  Here, since the humidifier 42 and the cathode channel 13 have a small channel cross-sectional area and a large pressure loss, the air flows into the diluter 44 by bypassing the humidifier 42 and the cathode channel 13. To increase. Therefore, even if the purge valve 27 is not completely closed and hydrogen flows into the diluter 44 through the pipe 27b, this hydrogen is well diluted by the air having an increased flow rate. It will not be discharged outside the vehicle.

  Here, as the amount of change ΔP2 in step S107 increases, the amount of hydrogen leakage is expected to increase. Therefore, in order to increase the amount of air that bypasses and flows into the diluter 44, the compressor increases as the amount of change ΔP2 increases. It is good also as a structure which raises the rotational speed of 41. FIG.

Thereafter, the processing of the ECU 70 proceeds to the end, and a series of processing ends.
When there is a risk of hydrogen leakage in this way, the amount of air is increased and dilution is performed reliably, so that power generation of the fuel cell stack 10 can be continued, and the fuel cell vehicle can output the fuel cell stack 10. The vehicle can be self-propelled by the electric power to be driven, and can also be self-propelled by the electric power of the battery 55 (battery can be driven), so the driver can bring the fuel cell vehicle to a repair shop or the like. In this case, the shutoff valve 22 is closed when the predetermined time has elapsed from the determination that there is a risk of hydrogen leakage (Yes in S107) or when switching to battery running so that the hydrogen leakage is reliably stopped. Also good.

In step S121, the ECU 70 operates the fuel cell system 1 in the normal mode.
Specifically, ECU 70 normally calculates a target current based on the accelerator opening, and outputs this target current to power controller 53 as a command value. Note that the target current increases as the accelerator opening increases.

  The ECU 70 controls the purge valve 27 normally. The purge valve 27 is normally controlled when the prohibition of purge by the purge valve 27 is canceled. For example, when the minimum cell voltage detected via the cell voltage monitor 15 is equal to or lower than a predetermined cell voltage, circulating impurities (water vapor , Nitrogen, etc.) to discharge the purge valve 27 at a predetermined valve opening time.

  Thereafter, the processing of the ECU 70 returns to the start through a return.

  As described above, according to the fuel cell system 1, when it is determined in step S103 that the pressure change amount ΔP1 is equal to or less than the predetermined value and the pressure in the anode flow path 12 of the fuel cell stack 10 is constant, the anode (gas ) A series of processing (S104 to S107) related to leakage determination is executed. Here, the pressure change amount ΔP1 is a predetermined value or less in many cases, such as when idling such as waiting for a signal or waiting for a person, or when cruising at a constant speed (during constant speed travel). Since the purge valve 27 normally receives a valve closing command, the chance of anode leakage determination increases.

≪Modification≫
As mentioned above, although embodiment of this invention was described, this invention is not limited to this, For example, it can change as follows. Moreover, it can also combine suitably with embodiment mentioned later.

The following processing may be added between step S102 and step S103 in the above-described embodiment.
The ECU 70 calculates the total required power (required electric energy) required for the fuel cell stack 10 and the battery 55 from the motor 51 (external load) based on the accelerator opening.
Next, the ECU 70 considers the SOC detected via the SOC sensor 56, and the target anode pressure P1 (load of the fuel cell stack 10) when a part or all of the total required power is assisted (assisted) by the battery 55 is considered. ) Is calculated. In this case, the assist amount (discharge amount) of the battery 55 is calculated so that the target anode pressure P1 is continuously constant.
Next, in step S103, the ECU 70 executes a determination process based on the target anode pressure when assisting.

  With such a configuration, even if the accelerator opening varies, if the SOC of the battery 55 is sufficiently high, the assist amount can be varied and the target anode pressure P1 can be made constant continuously. Thereby, the opportunity to become step S103 · Yes increases, and the chance of anode leakage determination increases.

In addition, for example, when the fuel cell stack 10 is charged with the generated power of the fuel cell stack 10 while the fuel cell vehicle is stopped, the anode leakage determination may be performed.
Specifically, for example, when the vehicle speed detected via a vehicle speed sensor (vehicle speed detection means, not shown) mounted on the fuel cell vehicle is 0, the SOC detected via the SOC sensor 56 is the upper limit SOC. When it is less than (for example, 80%), the ECU 70 controls the power controller 53 and the like to increase the SOC of the battery 55 and bring it close to a fully charged state, thereby generating the fuel cell stack 10 with a constant power (current), The battery 55 is charged with this electric power. The ECU 70 determines that the load or the target anode pressure P1 of the fuel cell stack 10 is constant when the fuel cell stack 10 is generated with constant power (current) in this way, and step S103 · Yes in FIG. The subsequent steps S104 to S107 are executed.

Further, when the fuel cell vehicle is traveling at an extremely low speed, if it is subsequently determined that the load of the fuel cell stack 10 or the target anode pressure P1 is constant, the anode leakage determination may be executed.
Specifically, for example, when the vehicle speed is equal to or lower than a predetermined vehicle speed (for example, 5 km / h) corresponding to the lower limit value of the normal range of the load of the fuel cell stack 10 or the target anode pressure (target fuel gas pressure), Thereafter, when the fuel cell stack 10 is below the predetermined vehicle speed at which it is determined that the traveling of the fuel cell vehicle is maintained without changing the load or the target anode pressure (target fuel gas pressure), that is, in the fuel cell stack 10 When the required power for the fuel cell stack 10 is less than the lower limit value of the normal power generation region of the fuel cell stack 10 and there is a low possibility that the load of the fuel cell stack 10 or the target anode pressure (target fuel gas pressure) is subsequently changed, It is determined that the load of the fuel cell stack 10 or the target anode pressure (target fuel gas pressure) is constant, and the anode leakage determination is executed.

  In the above-described embodiment, the gas leak determination is performed based on the change ΔP2 of the actually measured anode pressure P2 at the predetermined time Δt2 in step S107 in FIG. The change rate (Pa / min) of the actually measured anode pressure P2 in seconds) is continuously monitored, and the change rate (Pa / min) of the actually measured anode pressure P2 that is larger than that based on the hydrogen consumption of the fuel cell stack 10 is a predetermined time. When continuously detected, it may be configured to determine that anode leakage has occurred.

  In the above-described embodiment, the fuel cell system 1 mounted on the fuel cell vehicle is exemplified, but the application location is not limited to this, and for example, a configuration incorporated in a stationary fuel cell system may be used.

<< Second Embodiment >>
Next, a second embodiment of the present invention will be described with reference to FIGS. In addition, a different part from 1st Embodiment is demonstrated.

In the second embodiment, the process of the ECU 70 proceeds from step S104 to step S201.
In step S201, the ECU 70 increases the target anode pressure P1 and the target cathode pressure and then keeps them constant (see FIG. 5). The increase ranges of the target anode pressure P1 and the target cathode pressure are obtained by a preliminary test or the like and stored in the ECU 70 in advance. Then, the ECU 70 controls the injector 24, the compressor 41, and the back pressure valve 43 so that the increased target anode pressure P1 and target cathode pressure are obtained. The hydrogen flow rate becomes constant after increasing.

In this way, by increasing the target anode pressure P1 and the target cathode pressure in conjunction with each other, the inter-electrode differential pressure (pressure difference between the anode channel 12 and the cathode channel 13) in the fuel cell stack 10 is predetermined. It can be kept below the value and the MEA can be protected. Further, by increasing the rotational speed of the compressor 41 in order to increase the target cathode pressure, the cathode off-gas flow rate also increases. Therefore, even if hydrogen leaks, it is diluted well by the diluter 44.
On the contrary, the target anode pressure P1 and the target cathode pressure may be decreased in conjunction with each other.

  Further, the ECU 70 increases the rotation speed of the hydrogen circulation pump 28 with respect to the normal time. This makes it difficult for the fuel cell stack 10 to be short of hydrogen. Further, the ECU 70 stores the current measured anode pressure P2 (t0) as an initial value.

  In step S202, it is determined whether or not a predetermined time Δt3 has elapsed since step S201. The predetermined time Δt3 is obtained by a preliminary test or the like and stored in the ECU 70 in advance.

  When it is determined that the predetermined time Δt3 has elapsed (S202 / Yes), the process of the ECU 70 proceeds to step S203. When it is determined that the predetermined time Δt3 has not elapsed (S202: No), the ECU 70 repeats the determination in step S202.

  In step S203, the ECU 70 determines whether or not the change amount ΔP2 of the measured anode pressure P2 is equal to or less than a predetermined change amount ΔP6. The predetermined change amount ΔP6 is obtained by a preliminary test or the like and is stored in the ECU 70.

  When it is determined that the change amount ΔP2 is equal to or less than the predetermined change amount ΔP6 (S203 / Yes), the process of the ECU 70 proceeds to step S204. When the process proceeds to step S204 as described above, the measured anode pressure P2 does not increase although the target anode pressure P1 is increased in step S201, and there is a possibility of anode leakage (see FIG. 5). ).

  When it is determined that the change amount ΔP2 is not equal to or less than the predetermined change amount ΔP6 (S203, No), the process of the ECU 70 proceeds to step S205.

  In step S204, the ECU 70 increments the gas leak determination flag (counter) by “+1”. The gas leak determination flag is used to count the number of times that the step S203 is Yes in the current series of gas leak determination processing.

  In step S205, the ECU 70 determines whether or not the determination in step S203 has been repeated a predetermined number of times (for example, 3 to 5 times) in the current series of gas leakage determination processes.

  If it is determined that the process has been repeated a predetermined number of times (Yes in S205), the process of the ECU 70 proceeds to step S206. When it is determined that the predetermined number of times has not been repeated (No at S205), the process of the ECU 70 proceeds to step S207.

  In step S206, the ECU 70 determines whether or not the gas leak determination flag (counter) is a predetermined value (for example, 2 to 4) or more. The predetermined value is set corresponding to a predetermined number (for example, 3 to 5 times) which is a criterion for determining the number of repetitions in step S205.

  When it is determined that the gas leak determination flag (counter) is equal to or greater than the predetermined value (S206 / Yes), the process of the ECU 70 proceeds to step S108. Thus, when it progresses to step S108, it is a case where it is judged that there exists a possibility of anode leakage.

  If it is determined that the gas leak determination flag (counter) is not equal to or greater than the predetermined value (No at S206), the process of the ECU 70 proceeds to step S121. Thus, when it progresses to step S121, it is a case where it is judged that there is no possibility of an anode leak, and this series of gas leak determination processes are complete | finished.

  In step S207, the ECU 70 decreases the target anode pressure P1 and the target cathode pressure. If the target anode pressure P1 and the target cathode pressure are reduced in step S201, the target anode pressure P1 and the target cathode pressure are increased in step S207.

  In step S208, the ECU 70 determines whether or not a predetermined time Δt4 has elapsed after step S205 · No. The predetermined time Δt4 is set to a time during which the measured anode pressure P2 and the actual cathode pressure are reduced to the initial state.

  If it is determined that the predetermined time Δt4 has elapsed (S208, Yes), the processing of the ECU 70 proceeds to step S201. When it is determined that the predetermined time Δt4 has not elapsed (S208, No), the ECU 70 repeats the determination in step S208.

  According to the second embodiment, when the series of gas leak determination processes (S201 to S204) is repeated a predetermined number of times (Yes in S205), the gas leak flag (counter) is equal to or greater than a predetermined value. (S206 / Yes) Since it is determined that a gas leak has occurred, erroneous determination can be prevented.

≪Modification≫
In the above-described embodiment, whether or not gas has leaked in the anode system (whether or not it has failed) based on the measured anode pressure P2 after the predetermined time Δt3 has elapsed since the target anode pressure P1 has been increased or decreased. Although the configuration for determining is exemplified, for example, in addition to / in place of the actually measured anode pressure P2, the configuration may be determined based on the supply amount of hydrogen (for example, the operation amount (hydrogen injection amount) of the injector 24). Good.

  Moreover, when determining gas leak, it is good also as a structure judged based on the hydrogen supply amount when the target anode pressure P1 is made constant. When the target anode pressure P1 is constant, the hydrogen supply amount increases more than expected when gas is leaking.

1 Fuel Cell System 10 Fuel Cell Stack (Fuel Cell)
11 Single cell (fuel cell)
12 Anode channel (fuel gas channel)
13 Cathode channel (oxidant gas channel)
21a, 22a, 23a, 24a, 25a Piping (fuel gas supply flow path)
24 injector (fuel gas flow rate control means)
26a, 28a, 28b Piping (fuel gas circulation flow path)
28 Hydrogen circulation pump (fuel gas circulation pump)
26a, 27a, 27b, 44a Piping (fuel off gas discharge flow path)
27 Purge valve 31, 32, 33 Pressure sensor (pressure detection means)
51 Motor (external load)
55 Battery (electric storage means)
56 SOC sensor (electric storage amount detection means)
70 ECU (constant judgment means, gas leak judgment means)
P1 Target anode pressure P2, P3 Actual measured anode pressure

Claims (9)

A fuel cell having a fuel gas channel, and generating power by supplying fuel gas to the fuel gas channel;
A fuel gas supply channel connected to an inlet of the fuel gas channel and through which a fuel gas directed to the fuel gas channel flows;
A fuel gas flow rate control means for controlling the flow rate of the fuel gas, provided in the fuel gas supply flow path;
A fuel off-gas discharge passage connected to an outlet of the fuel gas passage and through which fuel off-gas flows from the fuel gas passage to the outside;
A purge valve provided in the fuel off-gas discharge flow path for discharging / blocking the fuel off-gas;
Constant determination means for determining whether the load of the fuel cell or the target fuel gas pressure is constant;
Gas leakage determination means for determining whether or not gas is leaking based on the pressure of the gas between the fuel gas flow rate control means and the purge valve;
With
When the valve closing command is input to the purge valve when the constant determining unit determines that the constant is constant,
The fuel gas flow rate control means makes the flow rate of the fuel gas constant, and the gas leak judgment means executes gas leak judgment. Power storage means for storing power in parallel with the fuel cell with respect to an external load;
A storage amount detection means for detecting a storage amount of the storage means;
With
The constant determination means determines whether or not the load of the fuel cell or the target fuel gas pressure is constant when the electric storage means assists the required electric energy from the external load based on the storage amount of the electric storage means. The fuel cell system according to claim 1, wherein the fuel cell system is determined. Mounted on the vehicle,
Vehicle speed detecting means for detecting the vehicle speed of the vehicle,
The constant determination means includes
The vehicle speed detected by the vehicle speed detecting means is not more than a predetermined vehicle speed corresponding to the lower limit of the normal range of the load or target fuel gas pressure of the fuel cell, and thereafter the load of the fuel cell or target fuel gas When the vehicle speed is less than or equal to a predetermined vehicle speed that is determined to maintain the running of the vehicle without changing the pressure,
The fuel cell system according to claim 1, wherein it is determined that a load of the fuel cell or a target fuel gas pressure is constant. Power storage means for storing power of the fuel cell;
Power control means for controlling power generation of the fuel cell, and for controlling power storage in the power storage means;
With
When the power control means causes the fuel cell to generate power with constant power and stores the constant power of the fuel cell in the power storage means,
The fuel cell system according to claim 1, wherein the constant determination unit determines that the load of the fuel cell or the target fuel gas pressure is constant. When performing the gas leak determination by the gas leak determination means,
The fuel cell system according to any one of claims 1 to 4, wherein the fuel gas flow rate control means sets a flow rate of the fuel gas as a flow rate for gas leakage determination. The fuel cell system according to claim 5, wherein the gas leak determination flow rate is set based on a fuel gas consumption amount consumed by the fuel cell that generates power. The gas leak determination flow rate is set based on a fuel gas consumption amount consumed by the fuel cell to generate power and a fuel gas leak amount leaking from the fuel gas flow channel of the fuel cell to the oxidant gas flow channel. The fuel cell system according to claim 5, wherein: The fuel off-gas discharge channel upstream of the purge valve is connected to the fuel gas supply channel downstream of the fuel gas flow rate control means, and fuel off-gas containing fuel gas is passed from the fuel off-gas discharge channel to the fuel gas. A fuel gas circulation flow path for returning to the supply flow path and circulating the fuel gas;
A fuel gas circulation pump that circulates the fuel gas so as to pass through the fuel gas flow path and the fuel gas circulation flow path by operating;
With
The fuel gas circulation pump increases the amount of gas circulation when the gas leak determination unit executes the gas leak determination and when the gas leak determination is not executed, which is normal. The fuel cell system according to claim 4. A fuel cell having a fuel gas channel, and generating power by supplying fuel gas to the fuel gas channel;
A fuel gas supply channel connected to an inlet of the fuel gas channel and through which a fuel gas directed to the fuel gas channel flows;
A fuel gas flow rate control means for controlling the flow rate of the fuel gas, provided in the fuel gas supply flow path;
A fuel off-gas discharge channel through which the fuel off-gas flowing from the fuel gas channel to the outside flows;
A purge valve provided in the fuel off-gas discharge flow path for discharging / blocking the fuel off-gas;
A method for operating a fuel cell system comprising:
A constant determination step of determining whether the load of the fuel cell or the target fuel gas pressure is constant;
When it is determined to be constant in the constant determination step and when a valve closing command is input to the purge valve, the fuel gas flow rate control means makes the flow rate of the fuel gas constant, and the fuel gas flow rate control means A gas leakage determination step for determining whether or not gas is leaking based on the pressure of the gas between the gas and the purge valve;
A method for operating a fuel cell system, comprising:

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