JP2007305563A - Fuel cell system, and method for estimating exhaust gas amount - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize an exhaust gas amount (an amount of purge) from an exhaust valve in a fuel cell system having a variable gas feeder. <P>SOLUTION: The fuel cell system 1 comprises: a fuel cell 2; a supply channel 22 for allowing fuel gas supplied from a fuel supply source 21 to the fuel cell 2; the variable gas feeder 28 for adjusting a gas state at the upstream side of the supply channel 22 for supplying to the downstream side; a discharge channel 23 for allowing fuel exhausted gas discharged from the fuel cell 2; and the exhaust valve 31 for discharging gas in the discharge channel 23 to the outside. The fuel cell system 1 has an exhaust control means 7 for controlling the open/close state of the exhaust valve 31 corresponding to a change in a gas supply state from the variable gas feeder 28. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell system and a displacement estimation method.

  2. Description of the Related Art Conventionally, a fuel cell system including a fuel cell that generates power by receiving a supply of reaction gas (fuel gas and oxidizing gas) has been proposed and put into practical use. Impurities such as nitrogen and carbon monoxide accumulate over time in the fuel cell of such a fuel cell system and in the circulation path of the fuel off gas with power generation. In order to discharge such impurities to the outside, an exhaust valve is provided in the exhaust flow path connected to the circulation flow path, and the exhaust valve is controlled to open and close to exhaust the gas in the circulation flow path at regular intervals. A technique for purging (purge technique) has been proposed.

In addition, at present, the discharge time depends on a technique for controlling the exhaust valve to close when the flow rate of the gas passing through the exhaust valve exceeds a predetermined value (see Patent Document 1) and the power generation state of the fuel cell. A technique (see Patent Document 2) that realizes exhaust of the same amount as the required emission amount corresponding to the power generation state is set.
JP 2004-179000 A Japanese Patent Laid-Open No. 2005-141977

  By the way, the fuel cell system is provided with a fuel supply channel for flowing fuel gas supplied from a fuel supply source such as a hydrogen tank to the fuel cell. In recent years, a technology has been proposed in which a variable gas supply device such as a mechanical variable regulator is provided in the fuel supply flow path to change the supply pressure of the fuel gas from the fuel supply source in accordance with the operating state of the system. Has been.

  When the variable gas supply device as described above is provided, the state quantities (pressure, flow rate, temperature, etc.) of the fuel gas supplied to the fuel cell change sequentially. Therefore, in a fuel cell system provided with a variable gas supply device, stabilization of the exhaust amount (purge amount) from the exhaust valve is realized only by adopting the technique described in Patent Document 1 and Patent Document 2. It was difficult to make.

  The present invention has been made in view of such circumstances, and an object of the present invention is to stabilize the exhaust amount (purge amount) from an exhaust valve in a fuel cell system including a variable gas supply device.

  In order to achieve the above object, a fuel cell system according to the present invention includes a fuel cell, a supply channel for flowing fuel gas supplied from a fuel supply source to the fuel cell, and an upstream side of the supply channel. A variable gas supply device that adjusts the gas state and supplies it to the downstream side, a discharge passage for flowing the fuel off-gas discharged from the fuel cell, and an exhaust valve for discharging the gas in the discharge passage to the outside And an exhaust control means for controlling the open / close state of the exhaust valve in response to a change in the gas supply state from the variable gas supply device.

  By adopting such a configuration, it is possible to realize control of the open / close state of the exhaust valve (change / correction of the open / close time of the exhaust valve, etc.) in response to a change in the gas supply state from the variable gas supply device. Therefore, in the fuel cell system including the variable gas supply device, the exhaust amount (purge amount) from the exhaust valve can be stabilized. The “gas state” means a gas state represented by a flow rate, pressure, temperature, molar concentration, etc., and particularly includes at least one of a gas flow rate and a gas pressure. The “gas supply state” means the gas state of the fuel gas supplied from the variable gas supply device to the fuel cell.

  In the fuel cell system, an exhaust control means for changing an open / close state of the exhaust valve based on at least one of a pressure change and a flow rate change of the fuel gas supplied from the variable gas supply device to the fuel cell can be employed. .

  In the fuel cell system, a gas / liquid separator may be provided in the discharge channel, and an exhaust / drain valve that serves as both drainage and exhaust from the liquid reservoir of the gas / liquid separator may be employed as the exhaust valve. .

  The fuel cell system may further include an exhaust amount calculating means for calculating an exhaust amount from when the exhaust valve is opened. In such a case, the exhaust control means for closing the exhaust valve when the exhaust amount calculated by the exhaust amount calculating means reaches a predetermined target exhaust amount (for example, a value set based on the power generation state of the fuel cell). Can be adopted.

  Further, in the fuel cell system, an exhaust valve closing delay amount is calculated based on a difference between the upstream pressure and the downstream pressure of the exhaust valve, and the exhaust gas is exhausted ahead of time based on the calculated closing delay amount. An exhaust control means for closing the valve may be employed.

  When such a configuration is adopted, the difference between the upstream side pressure and the downstream side pressure of the exhaust valve increases due to a change in the pressure of the fuel gas supplied from the variable gas supply device to the fuel cell, etc. Even in such a case, the exhaust valve can be closed in advance in time based on the closing delay amount. Accordingly, the exhaust valve closing delay can be suppressed. Note that the “closing delay amount” refers to exhaust gas in a predetermined reference state (for example, a constant state in which a difference between the upstream pressure and the downstream pressure of the exhaust valve is relatively small) and in a non-reference state. It means a physical quantity related to the closing delay, such as a closing delay time that is a difference between the closing time of the valve and an excess exhaust amount (exhaust amount exceeding the target exhaust amount) generated in correspondence with the closing delay time.

  Further, in the fuel cell system, the exhaust gas amount is normally calculated by the dilution gas supply means for supplying the dilution gas for diluting the gas discharged from the discharge passage through the exhaust valve, and the exhaust amount calculation means. An abnormality detecting means for determining whether or not there is an abnormality. In such a case, when the abnormality detection means determines that the exhaust amount calculation by the exhaust amount calculation means is not normally performed, the exhaust valve opening time according to the supply amount of the dilution gas from the dilution gas supply means It is possible to employ an exhaust control means for limiting the above.

  By adopting such a configuration, it is possible to prevent the exhaust valve from being kept open for a long time even in a situation where the exhaust amount calculation by the exhaust amount calculating means is not normally performed. Therefore, it is possible to suppress the high concentration fuel gas from being discharged from the exhaust valve.

  Further, in the fuel cell system, a dilution gas supply means for supplying an oxidizing off gas discharged from the fuel cell as a dilution gas can be employed.

  When such a configuration is employed, the oxidizing off gas discharged from the fuel cell can be effectively used as the dilution gas.

  Further, in the fuel cell system, an exhaust amount calculating means for calculating an exhaust amount from the exhaust valve based on a gas supply state from the variable gas supplying device, and an exhaust amount calculating means when an abnormality of the variable gas supplying device is detected. It is possible to employ an abnormality detection means that determines that the exhaust amount calculation based on is not normally performed.

  The fuel cell system may further include a sensor that detects a gas supply state from the variable gas supply device. In such a case, the exhaust amount calculation means for calculating the exhaust amount from the exhaust valve based on the gas supply state from the variable gas supply device, and the exhaust amount calculation by the exhaust amount calculation means when the sensor abnormality is detected are normally calculated. It is possible to employ an abnormality detection means that determines that it has not been performed.

  In the fuel cell system, an injector can be employed as the variable gas supply device.

  An injector is an electromagnetically driven opening and closing that can adjust the gas state (gas flow rate and gas pressure) by driving the valve body directly with a predetermined driving cycle with electromagnetic driving force and separating it from the valve seat It is a valve. The predetermined control unit drives the valve body of the injector to control the fuel gas injection timing and injection time, whereby the flow rate and pressure of the fuel gas can be controlled.

  Further, the exhaust amount estimation method according to the present invention adjusts a fuel cell, a supply channel for flowing fuel gas supplied from a fuel supply source to the fuel cell, and a gas state upstream of the supply channel. And a variable gas supply device that supplies the gas to the downstream side, a discharge passage for flowing the fuel off-gas discharged from the fuel cell, and an exhaust valve for discharging the gas in the discharge passage to the outside. A method for estimating an exhaust amount of a fuel cell system includes a calculation step of calculating an exhaust amount from an exhaust valve based on time integration of a change in a gas supply state from a variable gas supply device.

  When such a method is adopted, even when the gas supply state from the variable gas supply device changes while the gas in the discharge channel is being discharged to the outside (during the purge operation), the change (for example, variable) Accurately estimate (calculate) the exhaust amount (purge amount) from the exhaust valve based on the pressure drop on the downstream side of the gas supply device and the correction flow rate by the variable gas supply device to compensate for this pressure drop) Is possible. Therefore, if the opening / closing operation of the exhaust valve is controlled so that the estimated exhaust amount approaches the predetermined target exhaust amount, the control accuracy is improved, so that stabilization of the exhaust amount can be realized. The “gas state” means a gas state represented by a flow rate, pressure, temperature, molar concentration, etc., and particularly includes at least one of a gas flow rate and a gas pressure. The “gas supply state” means the gas state of the fuel gas supplied from the variable gas supply device to the fuel cell.

  In the exhaust amount estimation method, in the calculation step, a pressure change corresponding flow rate converted from a change in the downstream pressure of the variable gas supply device and a gas correction supply flow rate for compensating for a decrease in the downstream pressure of the variable gas supply device are calculated. By adding the time integration value, the exhaust amount from the exhaust valve can be calculated. The “gas correction supply flow rate” means the flow rate of the fuel gas supplied from the variable gas supply device to the fuel cell in order to compensate for the decrease in the downstream pressure of the variable gas supply device.

  In the exhaust amount estimation method, a sensor for detecting a gas supply state from the variable gas supply device is provided, and in the calculation step, a deviation between the gas supply state detected by the sensor and a predetermined target supply state is predetermined. It is preferable to start the time integration for the change in the gas supply state from the variable gas supply device from the time when the threshold value is exceeded.

  By doing so, it is possible to suppress an exhaust amount calculation error caused by a minute change in the gas supply state from the variable gas supply device (for example, a minute pressure change during drainage). The “target supply state” means a target value of the gas state of the fuel gas supplied from the variable gas supply device to the fuel cell (for example, the pressure value of the fuel gas immediately before exhaust).

  In the exhaust amount estimation method, the calculation step is a power generation correction step of correcting the exhaust amount from the exhaust valve based on a change in the consumption amount of the fuel gas during power generation of the fuel cell, or the fuel cell is discharged from the fuel cell. A temperature correction process that corrects the exhaust amount from the exhaust valve based on the temperature of the fuel off-gas, or a gas leak amount in the fuel gas passage of the fuel cell system (for example, oxidation from the fuel gas passage in the fuel cell through the electrolyte membrane It is preferable to include a leakage correction step of correcting the exhaust amount from the exhaust valve based on the fuel gas cross leak amount permeating into the gas flow path.

  ADVANTAGE OF THE INVENTION According to this invention, in the fuel cell system provided with the variable gas supply apparatus, it becomes possible to realize stabilization of the exhaust amount (purge amount) from the exhaust valve.

  Hereinafter, a fuel cell system 1 according to an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, an example in which the present invention is applied to an on-vehicle power generation system of a fuel cell vehicle (moving body) will be described.

  First, the configuration of the fuel cell system 1 according to the embodiment of the present invention will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, the fuel cell system 1 according to the present embodiment includes a fuel cell 2 that generates electric power upon receipt of reaction gas (oxidation gas and fuel gas), and air as the oxidation gas. An oxidant gas piping system 3 for supplying fuel gas, a fuel gas piping system 4 for supplying hydrogen gas as a fuel gas to the fuel cell 2, and a refrigerant piping system 5 for supplying a refrigerant to the fuel cell 2 to cool the fuel cell 2. A power system 6 that charges and discharges the power of the system and a control unit 7 that performs overall control of the entire system are provided.

  The fuel cell 2 is formed of, for example, a solid polymer electrolyte type and has a stack structure in which a large number of single cells are stacked. The unit cell of the fuel cell 2 has a pair of separators having an air electrode on one surface of an electrolyte made of an ion exchange membrane, a fuel electrode on the other surface, and further sandwiching the air electrode and the fuel electrode from both sides. have. The fuel gas is supplied to the fuel gas flow path of one separator and the oxidizing gas is supplied to the oxidizing gas flow path of the other separator, and the fuel cell 2 generates electric power by this gas supply. The fuel cell 2 is provided with a current sensor 2a for detecting a current during power generation.

  The oxidizing gas piping system 3 has an air supply passage 11 through which oxidizing gas supplied to the fuel cell 2 flows, and an exhaust passage 12 through which oxidizing off-gas discharged from the fuel cell 2 flows. The air supply flow path 11 is provided with a compressor 14 that takes in the oxidizing gas via the filter 13 and a humidifier 15 that humidifies the oxidizing gas fed by the compressor 14. Oxidized off-gas flowing through the exhaust passage 12 is subjected to moisture exchange in the humidifier 15 through the back pressure regulating valve 16 and then merged with the hydrogen off-gas in a diluter 34 described later to dilute the hydrogen off-gas (FIG. 1 Finally, the exhaust gas is exhausted into the atmosphere outside the system. The compressor 14 takes in the oxidizing gas in the atmosphere by driving a motor (not shown).

  The fuel gas piping system 4 includes a hydrogen supply source 21, a hydrogen supply passage 22 through which hydrogen gas supplied from the hydrogen supply source 21 to the fuel cell 2 flows, and a hydrogen offgas (fuel offgas) discharged from the fuel cell 2. A circulation channel 23 for returning to the junction A1 of the hydrogen supply channel 22, a hydrogen pump 24 for pumping the hydrogen off-gas in the circulation channel 23 to the hydrogen supply channel 22, and a branch connection to the circulation channel 23 And an exhaust drainage channel 25.

  The hydrogen supply source 21 corresponds to the fuel supply source in the present invention, and is configured by, for example, a high-pressure tank or a hydrogen storage alloy, and is configured to be able to store, for example, 35 MPa or 70 MPa of hydrogen gas. When a shut-off valve 26 described later is opened, hydrogen gas flows out from the hydrogen supply source 21 into the hydrogen supply flow path 22. The hydrogen gas is finally depressurized to about 200 kPa, for example, by a regulator 27 and an injector 28 described later, and supplied to the fuel cell 2. The hydrogen supply source 21 is composed of a reformer that generates a hydrogen-rich reformed gas from a hydrocarbon-based fuel and a high-pressure gas tank that stores the reformed gas generated by the reformer in a high-pressure state. May be. In addition, a tank having a hydrogen storage alloy can be employed as the hydrogen supply source 21.

  The hydrogen supply flow path 22 is provided with a shutoff valve 26 that shuts off or allows the supply of hydrogen gas from the hydrogen supply source 21, a regulator 27 that adjusts the pressure of the hydrogen gas, and an injector 28. A pressure sensor 29 that detects the pressure of the hydrogen gas in the hydrogen supply flow path 22 is provided on the downstream side of the injector 28 and upstream of the junction A1 between the hydrogen supply flow path 22 and the circulation flow path 23. It has been. Further, on the upstream side of the injector 28, a pressure sensor and a temperature sensor (not shown) for detecting the pressure and temperature of the hydrogen gas in the hydrogen supply flow path 22 are provided. Information relating to the gas state (pressure, temperature) of the hydrogen gas detected by the pressure sensor 29 or the like is used for feedback control and purge control of an injector 28 described later.

  The regulator 27 is a device that regulates the upstream pressure (primary pressure) to a preset secondary pressure. In this embodiment, a mechanical pressure reducing valve that reduces the primary pressure is employed as the regulator 27. The mechanical pressure reducing valve has a structure in which a back pressure chamber and a pressure adjusting chamber are formed with a diaphragm therebetween, and the primary pressure is reduced to a predetermined pressure in the pressure adjusting chamber by the back pressure in the back pressure chamber. Thus, a publicly known configuration for the secondary pressure can be employed. In the present embodiment, as shown in FIG. 1, the upstream pressure of the injector 28 can be effectively reduced by arranging two regulators 27 on the upstream side of the injector 28. For this reason, the design freedom of the mechanical structure (a valve body, a housing, a flow path, a drive device, etc.) of the injector 28 can be increased. In addition, since the upstream pressure of the injector 28 can be reduced, it is possible to prevent the valve body of the injector 28 from becoming difficult to move due to an increase in the differential pressure between the upstream pressure and the downstream pressure of the injector 28. be able to. Therefore, it is possible to widen the adjustable pressure width of the downstream pressure of the injector 28 and to suppress a decrease in responsiveness of the injector 28. The regulator 27 adjusts the gas state (gas pressure) on the upstream side of the hydrogen supply flow path 22 and supplies it to the downstream side, and corresponds to the variable gas supply device in the present invention.

  The injector 28 is an electromagnetically driven on-off valve capable of adjusting the gas flow rate and gas pressure by driving the valve body directly with a predetermined driving cycle with an electromagnetic driving force and separating it from the valve seat. The injector 28 includes a valve seat having an injection hole for injecting gaseous fuel such as hydrogen gas, a nozzle body for supplying and guiding the gaseous fuel to the injection hole, and an axial direction (gas flow direction) with respect to the nozzle body. And a valve body that is movably accommodated and opens and closes the injection hole. In the present embodiment, the valve body of the injector 28 is driven by a solenoid that is an electromagnetic drive device, and the opening area of the injection hole is made two or more stages by turning on and off the pulsed excitation current supplied to the solenoid. It can be switched. By controlling the gas injection time and gas injection timing of the injector 28 by the control signal output from the control unit 7, the flow rate and pressure of the hydrogen gas are controlled with high accuracy. The injector 28 directly opens and closes the valve (valve body and valve seat) with an electromagnetic driving force, and has a high responsiveness because its driving cycle can be controlled to a highly responsive region.

  Injector 28 changes downstream by changing at least one of the opening area (opening) and opening time of the valve provided in the gas flow path of injector 28 in order to supply the required gas flow rate downstream. The gas flow rate (or hydrogen molar concentration) supplied to the side (fuel cell 2 side) is adjusted. Since the gas flow rate is adjusted by opening and closing the valve body of the injector 28 and the gas pressure supplied downstream of the injector 28 is reduced from the gas pressure upstream of the injector 28, the injector 28 is controlled by a pressure regulating valve (pressure reducing valve, regulator). ). Further, in the present embodiment, a variable pressure control valve capable of changing the pressure adjustment amount (pressure reduction amount) of the upstream gas pressure of the injector 28 so as to match the required pressure within a predetermined pressure range according to the gas requirement. Can also be interpreted. The injector 28 adjusts the gas state (gas flow rate, hydrogen molar concentration, gas pressure) on the upstream side of the hydrogen supply flow path 22 and supplies it to the downstream side, and corresponds to the variable gas supply device in the present invention.

  In the present embodiment, as shown in FIG. 1, the injector 28 is disposed upstream of the junction A <b> 1 between the hydrogen supply channel 22 and the circulation channel 23. Further, as shown by a broken line in FIG. 1, when a plurality of hydrogen supply sources 21 are employed as the fuel supply source, a portion where the hydrogen gas supplied from each hydrogen supply source 21 merges (hydrogen gas merge portion A2). In addition, the injector 28 is arranged on the downstream side.

  An exhaust / drain channel 25 is connected to the circulation channel 23 via a gas / liquid separator 30 and an exhaust / drain valve 31. The gas-liquid separator 30 collects moisture from the hydrogen off gas. The exhaust / drain valve 31 operates according to a command from the control unit 7 to discharge moisture collected by the gas-liquid separator 30 and hydrogen off-gas (fuel off-gas) containing impurities in the circulation channel 23 to the outside. (Purge). By opening the exhaust / drain valve 31, the concentration of impurities in the hydrogen off-gas in the circulation passage 23 decreases, and the hydrogen concentration in the hydrogen off-gas supplied in circulation increases. An upstream pressure sensor 32 and a downstream pressure sensor 33 for detecting the pressure of the hydrogen off gas are provided at an upstream position (on the circulation flow path 23) and a downstream position (on the exhaust drain flow path 25) of the exhaust drain valve 31, respectively. It has been. Information relating to the pressure of the hydrogen off-gas detected by these pressure sensors is used for purge control described later. The circulation channel 23 is an embodiment of the discharge channel in the present invention, and the exhaust / drain valve 31 is an embodiment of the exhaust valve in the present invention.

  The hydrogen off-gas discharged through the exhaust / drain valve 31 and the exhaust / drain passage 25 is diluted by the diluter 34 by joining with the oxidizing off-gas (air) in the exhaust passage 12. The oxidizing off gas in the exhaust passage 12 is an example of a dilution gas in the present invention. The exhaust flow path 12 supplies a dilution gas (oxidation off gas) for diluting the hydrogen off gas discharged through the exhaust drain valve 31, and is an embodiment of the dilution gas supply means in the present invention. Equivalent to. The hydrogen pump 24 circulates and supplies the hydrogen gas in the circulation system to the fuel cell 2 by driving a motor (not shown). The hydrogen gas circulation system is constituted by a downstream channel of the junction A1 of the hydrogen supply channel 22, a fuel gas channel formed in the separator of the fuel cell 2, and a circulation channel 23. Become.

  The refrigerant piping system 5 includes a refrigerant channel 41 communicating with the cooling channel in the fuel cell 2, a cooling pump 42 provided in the refrigerant channel 41, and a radiator 43 that cools the refrigerant discharged from the fuel cell 2. And a temperature sensor 44 for detecting the temperature of the refrigerant discharged from the fuel cell 2. The cooling pump 42 circulates and supplies the refrigerant in the refrigerant channel 41 to the fuel cell 2 by driving a motor (not shown). The temperature of the refrigerant detected by the temperature sensor 44 (= temperature of hydrogen off-gas discharged from the fuel cell 2) is used for purge control described later.

  The power system 6 includes a high-voltage DC / DC converter 61, a battery 62, a traction inverter 63, a traction motor 64, various auxiliary machine inverters not shown, and the like. The high-voltage DC / DC converter 61 is a direct-current voltage converter that adjusts the direct-current voltage input from the battery 62 and outputs it to the traction inverter 63 side, and the direct-current input from the fuel cell 2 or the traction motor 64. And a function of adjusting the voltage and outputting it to the battery 62. The charge / discharge of the battery 62 is realized by these functions of the high-voltage DC / DC converter 61. Further, the output voltage of the fuel cell 2 is controlled by the high voltage DC / DC converter 61.

  The battery 62 is configured such that battery cells are stacked and a constant high voltage is used as a terminal voltage, and surplus power can be charged or power can be supplementarily supplied under the control of a battery computer (not shown). The traction inverter 63 converts a direct current into a three-phase alternating current and supplies it to the traction motor 64. The traction motor 64 is a three-phase AC motor, for example, and constitutes a main power source of a vehicle on which the fuel cell system 1 is mounted. The auxiliary inverter is an electric motor control unit that controls driving of each motor, converts a direct current into a three-phase alternating current, and supplies the three-phase alternating current to each motor. The auxiliary inverter is, for example, a pulse width modulation type PWM inverter, which converts the DC voltage output from the fuel cell 2 or the battery 62 into a three-phase AC voltage in accordance with a control command from the control unit 7 and is generated by each motor. To control the rotational torque.

  The control unit 7 detects an operation amount of an operation member (accelerator or the like) for acceleration provided in the vehicle, and receives control information such as an acceleration request value (for example, a required power generation amount from a load device such as the traction motor 64). To control the operation of various devices in the system. In addition to the traction motor 64, the load device is an auxiliary device necessary for operating the fuel cell 2 (for example, each motor of the compressor 14, the hydrogen pump 24, the cooling pump 42, etc.), and is involved in traveling of the vehicle. It is a collective term for power consumption devices including actuators used in various devices (transmissions, wheel control units, steering devices, suspension devices, etc.), air conditioners (air conditioners) for passenger spaces, lighting, audio, and the like.

  The control unit 7 is configured by a computer system (not shown). Such a computer system includes a CPU, a ROM, a RAM, an HDD, an input / output interface, a display, and the like. The CPU reads various control programs recorded in the ROM and executes a desired calculation, thereby performing a purge described later. Various processes and controls such as control are performed.

  Specifically, as shown in FIG. 2, the control unit 7 determines the flow rate of hydrogen gas consumed by the fuel cell 2 (hereinafter referred to as “hydrogen consumption”) based on the generated current value of the fuel cell 2 detected by the current sensor 2a. (Referred to as “amount”) (fuel consumption calculation function: B1). In the present embodiment, the hydrogen consumption is calculated and updated every calculation cycle of the control unit 7 using a specific calculation expression representing the relationship between the generated current value and the hydrogen consumption.

  The control unit 7 calculates a target pressure value at a downstream position of the injector 28 of hydrogen gas supplied to the fuel cell 2 based on the generated current value of the fuel cell 2 (target pressure value calculation function: B2). Then, the target purge amount (target discharge amount of hydrogen off gas from the exhaust / drain valve 31) is calculated (target purge amount calculation function: B3). In the present embodiment, the target pressure value and the target purge amount are calculated for each calculation cycle of the control unit 7 using a specific map representing the relationship between the generated current value, the target pressure value, and the target purge amount.

  Further, the control unit 7 calculates a deviation between the calculated target pressure value and the pressure value (detected pressure value) at the downstream position of the injector 28 detected by the pressure sensor 29 (pressure difference calculation function: B4). And the control part 7 calculates the hydrogen gas flow volume (feedback correction flow volume) added to hydrogen consumption in order to reduce the calculated deviation (correction flow volume calculation function: B5). In the present embodiment, the feedback correction flow rate is calculated using a target tracking control law such as PI control. Further, the control unit 7 calculates the injection flow rate of the injector 28 by adding the hydrogen consumption amount and the feedback correction flow rate (injection flow rate calculation function: B6). Then, the control unit 7 calculates the injection time of the injector 28 based on the calculated injection flow rate and drive cycle, and outputs a control signal for realizing this injection time, whereby the gas injection time and gas of the injector 28 are output. The injection timing is controlled to adjust the flow rate and pressure of the hydrogen gas supplied to the fuel cell 2.

  Further, the control unit 7 performs the feedback control of the injector 28 (control of the gas injection time and gas injection timing of the injector 28 so that the detected pressure value at the downstream position of the injector 28 follows the predetermined target pressure value). At the same time, by controlling the opening / closing of the exhaust / drain valve 31, moisture and hydrogen off-gas in the circulation passage 23 are discharged from the exhaust / drain valve 31 to the outside.

  At this time, the control unit 7 calculates the total discharge amount (purge amount) of the hydrogen off-gas from the exhaust drain valve 31 based on the change in the gas supply state from the injector 28 (purge amount calculation function: B7) and calculates It is determined whether or not the purge amount is equal to or greater than a predetermined target purge amount (purge amount deviation determination function: B8). Then, the control unit 7 opens the exhaust / drain valve 31 when the calculated purge amount is less than the target purge amount, and closes the exhaust / drain valve 31 when the calculated purge amount is equal to or larger than the target purge amount. (Purge control function: B9). That is, the control unit 7 functions as an exhaust control unit and an exhaust amount calculation unit in the present invention.

  The control unit 7 determines the exhaust drainage valve 31 based on the difference between the upstream pressure of the exhaust drainage valve 31 detected by the pressure sensor 32 and the downstream pressure of the exhaust drainage valve 31 detected by the pressure sensor 33. The closing delay amount is calculated (closing delay amount calculation function: B9a). Then, the control unit 7 closes the exhaust / drain valve 31 ahead of time based on the calculated closing delay amount. In the present embodiment, as the closing delay amount, a closing delay time of the exhaust drain valve 31 and an excess exhaust amount corresponding to the closing delay time (an exhaust amount exceeding the target purge amount) are employed.

  Here, the purge amount calculation function B7 of the control unit 7 will be described in more detail.

By the feedback control of the injector 28, the hydrogen off-gas is discharged from the circulation passage 23 by opening the exhaust / drain valve 31 in a state where the detected pressure value of the pressure sensor 29 at the downstream position of the injector 28 follows the target pressure value. As a result, the detected pressure value temporarily decreases. The control unit 7 calculates a pressure decrease due to such hydrogen off-gas discharge (purge), and based on the calculated pressure decrease and the temperature of the refrigerant detected by the temperature sensor 44, the pressure is reduced. A discharge amount of hydrogen off-gas corresponding to the decrease (flow rate corresponding to pressure change) is calculated (pressure change corresponding flow rate calculation function: B7a). In the present embodiment, the pressure change-compatible flow rate “Q ₁ ” is calculated using the following equation.

  In the above equation, “ΔP” is the pressure drop obtained by subtracting the hydrogen gas pressure value (hydrogen current pressure) after purging from the hydrogen gas pressure value (hydrogen reference pressure) just before purging at the downstream position of the injector 28. Means. “Pa” is the standard atmospheric pressure, “V” is the hydrogen-based volume, “T” is the temperature of the refrigerant detected by the temperature sensor 44 (= temperature of the hydrogen off-gas discharged from the fuel cell 2), Each means.

Further, the control unit 7 calculates a feedback correction flow rate (gas correction supply flow rate) for compensating for the pressure drop caused by the discharge (purging) of hydrogen off-gas (correction flow rate calculation function: B5). It calculates the time integration value Q ₂ from the purge start time (correction flow rate integrating function: B7b). In the present embodiment, a predetermined dead zone is provided in the pressure sensor 29, and the absolute value of the deviation between the current hydrogen pressure (gas supply state) detected by the pressure sensor 29 and the hydrogen reference pressure (target supply state) is predetermined. When the threshold value is exceeded, the control unit 7 starts the time integration of the feedback correction flow rate. By doing in this way, it becomes possible to suppress the influence of the minute pressure fluctuation at the time of drainage.

Further, the control unit 7 calculates a time integrated value Q ₃ of hydrogen consumption variation in the fuel cell 2 from the purge start time (hydrogen consumption variation totalization function: B7c) with hydrogen in the downstream position of the injector 28 Based on the pressure value of the gas (the pressure value detected by the pressure sensor 29), the amount of cross leak Q ₄ (the amount of hydrogen gas that permeates from the fuel gas channel inside the fuel cell 2 to the oxidizing gas channel through the electrolyte membrane) Amount) (cross leak amount calculation function: B7d). In the present embodiment, by using a specific map indicating a relationship between the pressure value of the hydrogen gas and the amount of cross leak in the downstream position of the injector 28, and it calculates the cross leak amount Q _4.

Then, the control unit 7 calculates the fuel cell from the purge start time from the value (Q ₁ + Q ₂ ) obtained by adding the pressure change corresponding flow rate Q ₁ and the time integrated value Q ₂ from the purge correction flow rate start time. 2 calculates the total discharge amount (purge amount Q) of hydrogen off-gas from the exhaust / drain valve 31 by subtracting the time integrated value Q ₃ and the cross leak amount Q ₄ for the change in the hydrogen consumption amount in 2 (purge amount calculation function) : B7).

Further, the control unit 7 determines whether or not the calculation of the purge amount Q is normally performed, and when it is determined that the calculation of the purge amount Q is not normally performed, the control unit 7 passes the exhaust passage 12. The valve opening time of the exhaust / drain valve 31 is limited according to the supply amount of the oxidizing off gas (dilution gas) supplied. That is, the control unit 7 also functions as an abnormality detection unit in the present invention. Various methods can be employed for determining whether the purge amount Q is abnormal. For example, when an abnormality such as a disconnection or a short circuit occurs in the injector 28 or when the pressure sensor 29 disposed on the downstream side of the injector 28 breaks down, the above-described flow rate Q ₁ corresponding to the pressure change is accurately calculated. Therefore, the purge amount Q cannot be calculated normally. Therefore, when the abnormality of at least one of the injector 28 and the pressure sensor 29 is detected, it can be determined that the purge amount Q is not normally calculated.

  Subsequently, the operation method of the fuel cell system 1 according to the present embodiment will be described using the flowcharts of FIGS. 3 and 4, the time charts of FIGS. 5 to 7, and the map of FIG. 8.

  During normal operation of the fuel cell system 1, hydrogen gas is supplied from the hydrogen supply source 21 to the fuel electrode of the fuel cell 2 through the hydrogen supply channel 22, and the air whose humidity has been adjusted is supplied to the air supply channel 11. Is supplied to the oxidation electrode of the fuel cell 2 through the electric power to generate electricity. At this time, electric power (required electric power) to be drawn from the fuel cell 2 is calculated by the control unit 7, and hydrogen gas and air in amounts corresponding to the amount of power generation are supplied into the fuel cell 2. In the present embodiment, during such a normal operation, feedback control of the injector 28 is performed, and purge control of the exhaust drain valve 31 (in order to discharge moisture or hydrogen off-gas staying in the circulation flow path 23 to the outside). Open / close control of the exhaust drain valve 31).

  First, as shown in the flowchart of FIG. 3, the control unit 7 of the fuel cell system 1 calculates a current value during power generation of the fuel cell 2 using the current sensor 2a (current detection step: S1). Next, the control unit 7 calculates the hydrogen consumption in the fuel cell 2 based on the detected current value (hydrogen consumption calculation step: S2), and downstream of the injector 28 for the hydrogen gas supplied to the fuel cell 2. A target pressure value and a target purge amount at the position are calculated (target value calculation step: S3).

  Next, the control unit 7 detects the pressure value on the downstream side of the injector 28 using the pressure sensor 29 (pressure value detection step: S4). Next, the control unit 7 adds to the hydrogen consumption in order to reduce the deviation between the target pressure value calculated in the target value calculation step S3 and the pressure value (detected pressure value) detected in the pressure value detection step S4. The hydrogen gas flow rate (feedback correction flow rate) is calculated (correction flow rate calculation step: S5). Next, the control unit 7 calculates the injection flow rate of the injector 28 by adding the hydrogen consumption amount and the feedback correction flow rate, and calculates the injection time of the injector 28 based on the injection flow rate and the driving cycle. And the control part 7 controls the gas injection time and gas injection timing of the injector 28 by outputting the control signal for implement | achieving this injection time, the flow volume of the hydrogen gas supplied to the fuel cell 2, and The pressure is adjusted (feedback control step: S6).

  The control unit 7 determines whether or not there is a purge start request while realizing the feedback control step S6 (purge request determination step: S7). In the present embodiment, when the amount of water accumulated in the liquid reservoir of the gas-liquid separator 30 exceeds a predetermined threshold, a liquid amount sensor not shown outputs a purge start request signal to the controller 7. It is like that. When it is determined in the purge request determination step S7 that there is no purge start request, the control unit 7 closes the exhaust drain valve 31 (purge valve closing step: S11). On the other hand, the control unit 7 receives the purge start request signal in the purge request determination step S7, determines that there is a purge start request, and if the gas injection from the injector 28 has already started, the exhaust drain valve 31 Is opened (purge valve opening step: S8). As shown in FIGS. 5 (A) to 5 (C), when the exhaust drain valve 31 is opened in the purge valve opening step S8, the water accumulated in the gas-liquid separator 30 is transferred to the exhaust drain passage 25. The hydrogen off-gas in the circulation channel 23 is discharged to the exhaust drainage channel 25 almost simultaneously with the completion of the moisture discharge.

The controller 7 estimates the total amount of hydrogen off-gas discharged from the exhaust drain valve 31 (purge amount Q) simultaneously with the opening of the exhaust drain valve 31 (purge amount estimation step: S9). The purge amount estimation step S9 will be described in detail later using the flowchart of FIG. Then, the control unit 7 determines whether the total emissions of the hydrogen off-gas was estimated purge amount estimation step S9 (purge amount Q) is the target value calculated target purge amount calculated in step S3 Q ₀ or more (Purge amount determination step: S10). Then, the control unit 7, when the estimated purge amount Q is less than the target purge amount Q ₀ is continued while continuing the purge amount estimation step S9 and the purge amount judgment step S10, the estimated purge amount Q is the target purge If it is the amount _{Q 0} or closes the water discharge valve 31 (purge valve closed step: S11).

In the purge valve closing step S <b> 11, the control unit 7 is based on the difference between the upstream pressure of the exhaust / drain valve 31 detected by the pressure sensor 32 and the downstream pressure of the exhaust / drain valve 31 detected by the pressure sensor 33. Then, the closing delay amount of the exhaust / drain valve 31 (the closing delay time Δt shown in FIG. 6B and the excess purge amount ΔQ corresponding to the closing delay time Δt shown in FIG. 6C) is calculated. Then, as shown in FIG. 6 (D), the control unit 7 closes the exhaust / drain valve 31 in advance by the calculated closing delay time Δt. As a result, by reducing the actual purge amount by the amount of excess purge amount Delta] Q, it is possible to match the target purge amount Q ₀ of the actual purge amount Q as shown in FIG. 6 (E).

  Here, the purge amount estimation step S9 will be described with reference to the flowchart of FIG.

First, the control unit 7 reduces the pressure drop ΔP (the value obtained by subtracting the current hydrogen pressure from the hydrogen reference pressure) on the downstream side of the injector 28 resulting from the discharge of the hydrogen off-gas by opening the exhaust / drain valve 31: FIG. 5 (D) and see), and the temperature T of the refrigerant detected by the temperature sensor 44, based on, and calculates the pressure change corresponding flow rate to Q ₁ as a flow rate corresponding to the pressure decrease amount [Delta] P (a pressure change corresponding flow rate calculation Step: S20). In the pressure change corresponding flow rate calculation step S20, the pressure change corresponding flow rate is calculated based on the refrigerant temperature T (= temperature of hydrogen off-gas discharged from the fuel cell 2) detected by the temperature sensor 44. The purge amount can be corrected based on the temperature change of the off gas.

Next, the control unit 7 calculates a feedback correction flow rate to compensate for the pressure drop on the downstream side of the injector 28 resulting from the discharge of the hydrogen off-gas due to the opening of the exhaust drain valve 31, and purge of this feedback correction flow rate A time integrated value Q ₂ (see FIG. 5E) from the start time is calculated (corrected flow integration step: S21). In the correction flow rate integration step S21, as shown in FIG. 7A, a dead zone is provided in the pressure sensor 29, and the current hydrogen pressure (gas supply state) detected by the pressure sensor 29 and the hydrogen reference pressure (target supply state). if) the absolute value of the deviation between exceeds a predetermined threshold value, so that to start the calculation of the feedback correction flow rate of the time integration value Q ₂ as shown in Figure 7 (B). The broken line in FIG. 7 indicates the control timing of the control unit 7.

The control unit 7 calculates a time integrated value Q ₃ of hydrogen consumption variation in the fuel cell 2 from the purge start time (hydrogen consumption variation integration step: S22). For example, assuming that the generated current value in the fuel cell 2 increases from the purge start point to the purge end point as shown in FIG. 5F, the time integrated value Q ₂ from the purge start point of the feedback correction flow rate is assumed. (A hatched area in the upper right of FIG. 5G) is a time integrated value Q ₃ corresponding to the change in hydrogen consumption corresponding to the current increase (intersection area of the hatched in the upper right and the lower right hatched in FIG. 5G). This is a value obtained by adding the pressure drop correction flow rate value. Therefore, when used as a time integration value Q ₂ of the feedback correction flow rate from the purge start time to calculate the purge amount, an amount corresponding error values Q ₃ corresponding to the current increase occurs. Therefore, in the present embodiment, and correcting the amount of purge by calculating the time integration value Q ₃ of hydrogen consumption variation corresponding to the current increment. The control unit 7 calculates the cross leak amount _{Q 4} (cross leak amount calculation step: S23).

Subsequently, the control unit 7, a pressure change corresponding flow rate Q _1, the time integration value Q ₂ and a value obtained by adding the feedback correction flow rate from the purge start time, hydrogen consumption variation in the fuel cell 2 from the purge start time by subtracting the time integrated value Q ₃ of the cross leak amount Q _4, and calculates the total emission amount of the hydrogen off-gas from the water discharge valve 31 (purge amount Q) (purge amount calculation step: S24). The purge amount estimation step S9 composed of the above process group corresponds to the exhaust amount estimation method in the present invention, and the purge amount calculation step S24 corresponds to the calculation step in the present invention. The pressure change corresponding flow rate calculation step S20 and the purge amount calculation step S24 correspond to the temperature correction step in the present invention, and the hydrogen consumption amount integration step S22 and the purge amount calculation step S24 correspond to the power generation correction step in the present invention. The cross leak amount calculation step S23 and the purge amount calculation step S24 correspond to the leak correction step in the present invention.

  If the control unit 7 determines that the purge amount Q is not normally calculated in the purge amount estimation step S9 by detecting an abnormality in the injector 28 or the pressure sensor 29, for example, the exhaust drain valve 31 valve opening time is limited. At this time, the control unit 7 is supplied to the diluter 34 via the exhaust passage 12 based on the generated current value of the fuel cell 2, the rotational speed of the compressor 14, the opening degree of the back pressure adjustment valve 16, and the like. The supply amount of the oxidizing off gas (dilution gas) is calculated, and the valve opening time of the exhaust / drain valve 31 is limited according to this supply amount.

Based on the map of FIG. 8A, when the supply amount of the oxidizing off-gas as a dilution gas is relatively small (q ₁ ), the hydrogen concentration of the gas diluted and discharged by the diluter 34 (exhaust hydrogen) It is estimated that (concentration) is relatively high (D ₁ ). Therefore, as shown in the map of FIG. 8B, the control unit 7 compares the maximum valve opening time of the exhaust drain valve 31 when the supply amount of the oxidizing off gas is relatively small (q ₁ ). Short (T ₁ ). This makes it possible to suppress an increase in the exhaust hydrogen concentration. On the other hand, based on the map of FIG. 8A, when the supply amount of the oxidizing off gas is relatively large (q ₂ ), the exhaust hydrogen concentration is estimated to be relatively low (D ₂ ). As shown in the map of FIG. 8B, the control unit 7 sets the maximum valve opening time of the exhaust / drain valve 31 to be relatively long (T ₂ ).

  In the fuel cell system 1 according to the embodiment described above, the control of the open / close state of the exhaust / drain valve 31 can be realized in response to a change in the gas supply state from the injector 28 (variable gas supply device). The exhaust amount (purge amount) of the hydrogen off gas from the exhaust drain valve 31 can be stabilized.

  In the fuel cell system 1 according to the embodiment described above, the closing delay amount of the exhaust / drain valve 31 is calculated based on the difference between the upstream pressure and the downstream pressure of the exhaust / drain valve 31, and the calculated closing Based on the delay amount, the exhaust drain valve 31 can be closed in advance in time. Therefore, the difference between the upstream pressure and the downstream pressure of the exhaust drain valve 31 is increased due to the change in the pressure of the hydrogen gas supplied from the injector 28 to the fuel cell 2, and the closing delay of the exhaust drain valve 31 is delayed. Even in the case assumed, the closing delay can be suppressed.

  Further, in the fuel cell system 1 according to the embodiment described above, when it is determined that the purge amount Q is not normally calculated, the exhaust drainage valve according to the supply amount of the oxidizing off gas (diluted gas). The valve opening time of 31 can be limited. Accordingly, even when the purge amount Q is not normally calculated, it is possible to prevent the exhaust drain valve 31 from being kept open for a long period of time. It becomes possible to suppress discharge. In the fuel cell system 1 according to the present embodiment, the oxidizing off gas discharged from the fuel cell 2 can be effectively used as the dilution gas, so that it is not necessary to newly generate the dilution gas.

  Further, when the purge amount estimation step S9 according to the embodiment described above is employed, the gas supply state from the injector 28 changes while the hydrogen off-gas in the circulation passage 23 is being discharged (during the purge operation). Also, the amount of purge from the exhaust / drain valve 31 is accurately estimated (calculated) based on the amount of change (the pressure drop on the downstream side of the injector 28 and the corrected flow rate by the injector 28 to compensate for this pressure drop). It becomes possible to do. Therefore, if the opening / closing operation of the exhaust / drain valve 31 is controlled so as to bring the estimated purge amount close to the predetermined target purge amount, the control accuracy is improved, so that the purge amount can be stabilized.

  Further, in the purge amount estimation step S9 according to the embodiment described above, when the deviation between the hydrogen current pressure detected by the pressure sensor 29 and the hydrogen reference pressure exceeds a predetermined threshold, the time integrated value of the feedback correction flow rate Therefore, the calculation error of the purge amount due to a minute change in the gas supply state from the injector 28 (for example, a minute pressure change during drainage or the like) can be suppressed.

  In the above embodiment, the example in which the circulation channel 23 is provided in the hydrogen gas piping system 4 of the fuel cell system 1 has been shown. However, for example, as shown in FIG. It is also possible to eliminate the circulation channel 23 by connecting. Even when such a configuration (dead end method) is adopted, the control unit 7 controls the open / close state of the exhaust / drain valve 31 in response to a change in the gas supply state from the injector 28 as in the above-described embodiment. The same operational effects as in the above embodiment can be obtained.

  Further, in the above embodiment, the oxidizing off gas (air) supplied from the fuel cell 2 to the diluter 34 via the exhaust passage 12 is adopted as the dilution gas, and the exhaust passage 12 is used as the dilution gas supply means. However, the type of dilution gas and the configuration of the dilution gas supply means are not limited to this.

  Moreover, in the above embodiment, although the example which provided the hydrogen pump 24 in the circulation flow path 23 was shown, it replaces with the hydrogen pump 24 and an ejector may be employ | adopted. Moreover, in the above embodiment, although the example which provided the exhaust_drain_valve 31 which implement | achieves both exhaust_gas | exhaustion and waste_water | drain in the circulation flow path 23 was shown, the water | moisture content collect | recovered with the gas-liquid separator 30 is discharged | emitted outside. A drain valve and an exhaust valve for discharging the gas in the circulation channel 23 to the outside can be provided separately, and the drain valve and the exhaust valve can be controlled separately by the control unit 7.

  Further, in the above embodiment, the pressure sensor 29 is arranged at the downstream position of the injector 28 in the hydrogen supply flow path 22 of the hydrogen gas piping system 4 and the pressure at this position is adjusted (approaches a predetermined target pressure value). Although the example in which the operating state of the injector 28 is set as described above is shown, the position of the pressure sensor for controlling the injector is not limited to this. For example, the position near the hydrogen gas inlet of the fuel cell 2 (on the hydrogen supply channel 22), the position near the hydrogen gas outlet of the fuel cell 2 (on the circulation channel 23), or the position near the outlet of the hydrogen pump 24 (circulation channel) 23) may be provided with a pressure sensor for controlling the injector. In such a case, a map in which the target pressure value at each position of the pressure sensor is recorded is created in advance, and the target pressure value recorded in this map and the pressure value (detected pressure value) detected by the pressure sensor are Based on this, a feedback correction flow rate is calculated.

  In the above embodiment, the example in which the shutoff valve 26 and the regulator 27 are provided in the hydrogen supply flow path 22 has been described. However, the injector 28 functions as a variable pressure control valve and shuts off the supply of hydrogen gas. Therefore, it is not always necessary to provide the shut-off valve 26 and the regulator 27. Therefore, when the injector 28 is employed, the shutoff valve 26 and the regulator 27 can be omitted, and the system can be reduced in size and cost.

  In the above embodiment, an example in which the hydrogen consumption amount, the target pressure value, and the target purge amount are set based on the generated current value of the fuel cell 2 has been described. However, other physical quantities indicating the operating state of the fuel cell 2 are shown. (The generated voltage value or generated power value of the fuel cell 2, the temperature of the fuel cell 2, etc.) may be detected, and the hydrogen consumption, target pressure value and target purge amount may be set according to the detected physical quantity. In addition, the fuel cell 2 is in a stopped state, in an operating state at the time of start-up, in an operating state immediately before entering intermittent operation, in an operating state immediately after recovering from intermittent operation, or in a normal operating state It is also possible for the control unit to determine such an operating state and to set a hydrogen consumption amount or the like according to these operating states.

  Further, in each of the above embodiments, the example in which the fuel cell system according to the present invention is mounted on the fuel cell vehicle has been shown. However, the present invention is applied to various moving bodies (robots, ships, aircrafts, etc.) other than the fuel cell vehicle. Such a fuel cell system can also be mounted. Further, the fuel cell system according to the present invention may be applied to a stationary power generation system used as a power generation facility for a building (house, building, etc.).

1 is a configuration diagram of a fuel cell system according to an embodiment of the present invention. It is a control block diagram for demonstrating the control aspect of the control part of the fuel cell system shown in FIG. 2 is a flowchart for explaining a method of operating the fuel cell system shown in FIG. It is a flowchart for demonstrating the exhaust gas amount estimation method (purge amount estimation process) which concerns on embodiment of this invention. 2 is a time chart for explaining the operation method of the fuel cell system shown in FIG. 1, wherein (A) shows the opening / closing operation of the exhaust drain valve, (B) shows the drainage amount from the exhaust drain valve, (C ) Indicates the exhaust amount (purge amount) from the exhaust drain valve, (D) indicates a decrease in the injector downstream pressure caused by the purge, and (E) compensates for the decrease in the injector downstream pressure. (F) shows an increase in the generated current value of the fuel cell, (G) shows a feedback corrected flow rate to compensate for both the increment of the generated current value and the decrease in the pressure on the downstream side of the injector. It is what shows. FIG. 2 is a time chart for explaining delay correction of the fuel cell system shown in FIG. 1, (A) shows an exhaust drain valve open / close request signal, and (B) shows an exhaust drain valve when delay correction is not applied. (C) shows the exhaust amount (purge amount) from the exhaust drain valve when the delay correction is not applied, (D) shows the open / close operation of the exhaust drain valve when the delay correction is applied. (E) shows the exhaust amount (purge amount) from the exhaust / drain valve when delay correction is applied. (A) is a time chart for explaining the dead zone of the pressure sensor of the fuel cell system shown in FIG. 1, and (B) is feedback correction when the detected pressure value of the fuel cell system shown in FIG. 1 is out of the dead zone. It is a time chart for demonstrating that the time integration of flow volume is started. (A) is a map which shows the relationship between the supply amount of the dilution gas (oxidation off gas) and exhaust hydrogen concentration of the fuel cell system shown in FIG. 1, and (B) is the supply of the dilution gas of the fuel cell system shown in FIG. It is a map which shows the relationship between quantity and the maximum valve opening time. It is a block diagram which shows the modification of the fuel cell system shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 2 ... Fuel cell, 7 ... Control part (Exhaust control means, Exhaust amount calculation means, Abnormality detection means), 12 ... Exhaust flow path (dilution gas supply means), 21 ... Hydrogen supply source (fuel supply) Source), 22 ... Hydrogen supply channel (supply channel), 23 ... Circulation channel (discharge channel), 28 ... Injector (variable gas supply device), 29 ... Pressure sensor, 30 ... Gas-liquid separator, 31 ... Exhaust drain valve (exhaust valve), 35 ... discharge channel.

Claims (18)

A fuel cell, a supply channel for flowing fuel gas supplied from a fuel supply source to the fuel cell, and a variable gas supply device that adjusts the gas state on the upstream side of the supply channel and supplies it to the downstream side And a fuel cell system comprising: a discharge passage for flowing a fuel off gas discharged from the fuel cell; and an exhaust valve for discharging the gas in the discharge passage to the outside.
A fuel cell system comprising exhaust control means for controlling an open / close state of the exhaust valve in response to a change in a gas supply state from the variable gas supply device. The exhaust control means changes an open / close state of the exhaust valve based on at least one of a pressure change and a flow rate change of the fuel gas supplied from the variable gas supply device to the fuel cell.
The fuel cell system according to claim 1. Comprising a gas-liquid separator provided in the discharge flow path;
The exhaust valve is an exhaust / drain valve that serves as both drainage and exhaust from the liquid reservoir of the gas-liquid separator.
The fuel cell system according to claim 1 or 2. An exhaust amount calculating means for calculating an exhaust amount from the opening time of the exhaust valve;
The exhaust control means closes the exhaust valve when the exhaust amount calculated by the exhaust amount calculating means reaches a predetermined target exhaust amount.
The fuel cell system according to any one of claims 1 to 3. The exhaust control unit closes the exhaust valve when the exhaust amount calculated by the exhaust amount calculating unit reaches a target exhaust amount set based on a power generation state of the fuel cell.
The fuel cell system according to claim 4. The exhaust control means calculates a closing delay amount of the exhaust valve based on a difference between an upstream pressure and a downstream pressure of the exhaust valve, and precedes in time based on the calculated closing delay amount. Which closes the exhaust valve,
The fuel cell system according to claim 4. Dilution gas supply means for supplying a dilution gas for diluting the gas discharged from the discharge passage through the exhaust valve;
An abnormality detecting means for determining whether or not the exhaust amount calculation by the exhaust amount calculating means is normally performed,
The exhaust control means, when the abnormality detection means determines that the exhaust amount calculation by the exhaust amount calculation means is not normally performed, the exhaust control means according to the supply amount of the dilution gas from the dilution gas supply means It limits the opening time of the exhaust valve,
The fuel cell system according to any one of claims 4 to 6. The dilution gas supply means supplies oxidation off-gas discharged from the fuel cell as the dilution gas.
The fuel cell system according to claim 7. The exhaust amount calculation means calculates an exhaust amount from the exhaust valve based on a gas supply state from the variable gas supply device,
The abnormality detection means determines that the exhaust amount calculation by the exhaust amount calculation means is not normally performed when an abnormality of the variable gas supply device is detected.
The fuel cell system according to claim 7 or 8. A sensor for detecting a gas supply state from the variable gas supply device;
The exhaust amount calculation means calculates an exhaust amount from the exhaust valve based on a gas supply state from the variable gas supply device,
The abnormality detection means determines that the exhaust amount calculation by the exhaust amount calculation means is not normally performed when an abnormality of the sensor is detected.
The fuel cell system according to claim 7 or 8. The variable gas supply device is an injector.
The fuel cell system according to any one of claims 1 to 10. A fuel cell, a supply channel for flowing fuel gas supplied from a fuel supply source to the fuel cell, and a variable gas supply device that adjusts the gas state on the upstream side of the supply channel and supplies it to the downstream side And an exhaust valve for exhausting the fuel off-gas discharged from the fuel cell, and an exhaust valve for exhausting the gas in the exhaust channel to the outside. And
An exhaust amount estimation method including a calculation step of calculating an exhaust amount from the exhaust valve based on time integration of a change in a gas supply state from the variable gas supply device.   In the calculation step, a pressure change corresponding flow rate converted from a change in downstream pressure of the variable gas supply device, and a time integrated value of a gas correction supply flow rate to compensate for a decrease in downstream pressure of the variable gas supply device, The exhaust amount estimation method according to claim 12, wherein the exhaust amount from the exhaust valve is calculated by adding. A sensor for detecting a gas supply state from the variable gas supply device;
In the calculating step, the time integration for the change in the gas supply state from the variable gas supply device from the time when the deviation between the gas supply state detected by the sensor and the predetermined target supply state exceeds a predetermined threshold value. The exhaust amount estimation method according to claim 12, which starts the operation.   13. The exhaust amount estimation method according to claim 12, wherein the calculation step includes a power generation correction step of correcting an exhaust amount from the exhaust valve based on a change in fuel gas consumption during power generation of the fuel cell.   13. The exhaust amount estimation method according to claim 12, wherein the calculating step includes a temperature correction step of correcting an exhaust amount from the exhaust valve based on a temperature of a fuel off gas discharged from the fuel cell.   The exhaust amount estimation method according to claim 12, wherein the calculating step includes a leak correction step of correcting an exhaust amount from the exhaust valve based on a gas leak amount in a fuel gas flow path of the fuel cell system.   The amount of exhaust from the exhaust valve is corrected based on the amount of cross leak of fuel gas that permeates from the fuel gas channel in the fuel cell to the oxidizing gas channel through the electrolyte membrane in the leak correction step. The displacement estimation method according to claim 17.

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