JP2006236675A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To replace residual gas in a hydrogen circulation path with hydrogen without requiring much power consumption at system startup and without generating a noise. <P>SOLUTION: This fuel cell system is provided with the hydrogen circulation path 5 circulating unreacted hydrogen discharged from the fuel cell 1 through the fuel cell 1, a hydrogen discharge path 7 discharging gas in the hydrogen circulation path 5 out of a system, a purge valve 8 opening/closing the hydrogen discharge path 7, a buffer part 9 provided in the hydrogen discharge path 7 on an upstream side of the purge valve 8 and storing the gas to be discharged out of the system from the hydrogen circulation path 5, an opening and closing valve 10 provided on an upstream side of the buffer part 9, and controlling inflow of the gas into the buffer part 9, and an ECU14 discharging the residual gas pushed into the buffer part 9 out of the system by pushing the residual gas in the hydrogen circulation path 5 into the buffer part 9 by opening and closing the purge valve 8 and the opening and closing valve 10 respectively at system startup and by controlling opening of the purge valve 8 after closing the opening and closing valve 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system including a fuel cell that generates power by receiving supply of fuel gas and oxidant gas to a fuel electrode and an oxidant electrode, respectively.

  Conventionally, a fuel cell system having a fuel gas circulation path for circulating unreacted fuel gas discharged from a fuel cell to the fuel cell is known. According to such a fuel cell system, unreacted fuel gas is provided. By using the fuel efficiency can be improved. By the way, in such a fuel cell system, the power supply to the outside is stopped after the system is stopped, but the gas remaining in the system inside the fuel cell due to the oxidation reaction by the catalyst of the fuel electrode or the oxidant electrode. Is consumed. That is, air and hydrogen remain in the oxidant gas supply path and the fuel gas circulation path, respectively, and the remaining air and hydrogen are consumed inside the fuel cell after the system is stopped.

However, oxygen contained in the air is consumed inside the fuel cell, but nitrogen is not consumed and remains on the oxidizer electrode side. In addition, if nitrogen remains on the oxidant electrode side, the nitrogen partial pressure on the oxidant electrode side increases, whereas the gas pressure in the fuel gas circulation path decreases, so that nitrogen flows from the oxidant electrode side to the fuel electrode side. Leaks into the fuel gas circulation path. When the fuel cell is restarted in a state where nitrogen has permeated into the fuel gas circulation path, when the fuel gas is supplied to the fuel electrode, nitrogen becomes an obstacle and the fuel gas is not supplied to the fuel electrode. Efficiency drops. From such a background, the conventional fuel cell system discharges the residual gas in the fuel gas circulation path outside the system by opening the purge valve when the system is started, and all the residual gas in the fuel gas circulation path is discharged. The fuel cell is started after replacement with fuel gas (see, for example, Patent Document 1).
JP 2004-193107 A

  However, since the conventional fuel cell system is configured to dilute the residual gas by a method such as diluting using an off-gas of the air system when the residual gas is discharged out of the system at the time of starting the system, At the same time as extra power is required to replace the residual gas in the gas circulation path with hydrogen, noise may be generated during startup.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fuel gas circulation path without requiring a large amount of power consumption and generating noise when the system is started. It is an object of the present invention to provide a fuel cell system capable of replacing residual gas in the inside with hydrogen.

  In order to solve the above-described problems, a fuel cell system according to the present invention includes a fuel gas circulation path for circulating unreacted fuel gas discharged from the fuel cell to the fuel cell, and a gas in the fuel gas circulation path. A fuel gas discharge path that discharges to the outside, a purge valve that opens and closes the fuel gas discharge path, and a fuel gas discharge path that is upstream of the purge valve are provided to store gas discharged out of the system from the fuel gas circulation path A buffer unit, an on-off valve provided on the upstream side of the buffer unit for controlling the inflow of gas into the buffer unit, and a fuel gas circulation path by closing and opening the purge valve and the on-off valve, respectively, at the time of system startup Control unit that discharges residual gas pushed into the buffer unit by controlling the opening of the purge valve after pushing the residual gas inside the buffer unit and closing the open / close valve Equipped with a.

  According to the fuel cell system of the present invention, at the time of starting the system, it is possible to replace the residual gas in the fuel gas circulation path with hydrogen without requiring much power consumption and without generating noise. it can.

  Hereinafter, the configuration of the fuel cell system according to the first and second embodiments of the present invention will be described with reference to the drawings.

[Configuration of fuel cell system]
A fuel cell system according to a first embodiment of the present invention is mounted on a vehicle, and as shown in FIG. 1, hydrogen as a fuel gas and an oxidant gas is provided at a fuel electrode (anode) and an oxidant electrode (cathode), respectively. And a fuel cell 1 that generates electric power by receiving supply of air. In this embodiment, the fuel cell 1 is constituted by a polymer electrolyte fuel cell, and the electrochemical reaction at the fuel electrode and the oxidant electrode and the electrochemical reaction as the entire fuel cell 1 are represented by the following formula (1 ) To (3).

[Chemical formula 1]
[Fuel electrode] H ₂ → 2H ⁺ + 2e ⁻ (1)
[Oxidant electrode] 1/2 O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O (2)
[Overall] H ₂ +1/2 O ₂ → H ₂ O (3)
[Configuration of hydrogen system]
The fuel cell system includes a high-pressure hydrogen tank 2 and a hydrogen pressure regulating valve 3 as a hydrogen system, and after adjusting the high-pressure hydrogen in the high-pressure hydrogen tank 2 to a pressure suitable for operating conditions by the hydrogen pressure regulating valve 3, a hydrogen supply path Hydrogen is supplied to the fuel electrode via 4. Further, unused hydrogen discharged from the fuel electrode side is circulated to the fuel electrode via the hydrogen circulation path 5 and the circulation pump 6. By providing the hydrogen circulation path 5 and the circulation pump 6, unused hydrogen discharged from the fuel electrode side can be reused, and the fuel efficiency of the fuel cell system can be improved.

  In the hydrogen circulation path 5 including the fuel electrode, impurity gas such as nitrogen and argon in the air leaking from the oxidizer electrode, or liquid water in which excessive moisture is liquefied may accumulate. These impurity gases lower the partial pressure of hydrogen to reduce power generation efficiency, or increase the average molecular weight of the circulating gas, making it difficult to circulate hydrogen. Liquid water also hinders hydrogen circulation. Therefore, a hydrogen discharge path 7 and a purge valve 8 that opens and closes the hydrogen discharge path 7 are provided on the outlet side of the fuel electrode. When the impurity gas or liquid water is accumulated, the purge valve 8 is opened by an instruction from the ECU 14 to perform a purge for discharging the impurity gas or liquid water from the fuel electrode to the outside of the system. Thereby, the hydrogen partial pressure and the circulation performance in the hydrogen circulation path 5 including the fuel electrode can be recovered.

  In this fuel cell system, a buffer unit 9 is provided on the upstream side of the purge valve 8 in the hydrogen discharge path 7. As will be described in detail later, by opening and closing the on-off valve 10, The remaining gas can be pushed into the buffer unit 9. The volume V of the buffer unit 9 is such that the volume Va of the gas existing in the hydrogen circulation path 5 is compressed to a predetermined pressure so that all the residual gas in the hydrogen circulation path 5 can be pushed in. 'Designed to be more than. Specifically, when the volume Va of the gas existing in the hydrogen circulation path 5 is 10 [l] and the compression pressure is 200 to 300 [kPa], the volume V of the buffer unit 9 is about 5 to 10 [l]. It becomes.

[Air system configuration]
The fuel cell system includes an air compressor 11 that compresses and supplies air as an air system, and the air compressor 11 supplies the compressed air to the oxidizer electrode. Then, unused air at the oxidizer electrode is discharged out of the system from the air discharge path 12. In this embodiment, the hydrogen discharge path 7 and the air discharge path 12 are connected on the downstream side, and the hydrogen discharged from the hydrogen discharge path 7 is diluted with air and discharged outside the system.

[Control system configuration]
The control system of the fuel cell system includes a pressure sensor 13a for detecting the pressure of hydrogen supplied to the fuel electrode, a pressure sensor 13b for detecting the pressure of the residual gas stored in the buffer unit 9, and the entire fuel cell system. ECU14 which controls operation | movement. In this control system, as shown in FIG. 2, hydrogen concentration estimation units 15 and 16 are provided in the buffer unit 9 and on the outlet side of the hydrogen discharge path 7, and discharged from the buffer unit 9 and the hydrogen discharge path 7. You may comprise so that the density | concentration of hydrogen can be estimated.

〔Start process〕
In general, the hydrogen concentration in the hydrogen circulation path 5 at the initial start of the fuel cell after stopping for a certain time is such that hydrogen introduced from the high-pressure hydrogen tank and the gas remaining in the hydrogen circulation path are alternately circulated. As shown in FIG. 3, it is known that the gas fluctuates greatly and the gases are mixed with the passage of time and gradually become a constant value. Further, it is known that if the gas with a low hydrogen concentration is introduced into the fuel cell for a long time and power generation is started during that time, the fuel cell will be deteriorated. Therefore, in the fuel cell system, the ECU 14 executes the startup process shown below, so that when the system is started, a large amount of power consumption is not required and noise is not generated. The residual gas of is immediately replaced with hydrogen. Hereinafter, with reference to the flowchart shown in FIG. 4, the operation of the ECU 14 when executing the startup process will be described in detail.

  The flowchart shown in FIG. 4 is started in response to the start request of the fuel cell system being input to the ECU 14, and the start-up process proceeds to step S1.

  In the process of step S1, the ECU 14 determines whether or not a hydrogen replacement process for replacing the residual gas in the hydrogen circulation path 5 with hydrogen is necessary. Specifically, when the fuel cell system is stopped in a state where the pressure in the hydrogen circulation path 5 (anode path) is higher than the atmospheric pressure and the hydrogen circulation path 5 is sealed, the ECU 14 is as shown in the flowchart in FIG. Next, it is determined whether or not the pressure in the hydrogen circulation path 5 is less than or equal to a predetermined value γ with reference to the detection result of the pressure sensor 13 (step S1a), and the pressure in the hydrogen circulation path 5 is less than or equal to the predetermined value γ. If there is, it is determined that a hydrogen replacement process is necessary, and the activation process proceeds to the process of step S2.

  On the other hand, when the fuel cell system is stopped in a state where the pressure in the hydrogen circulation path 5 is lower than the atmospheric pressure and the hydrogen system is sealed, the ECU 14 detects the pressure sensor 13a as shown in the flowchart of FIG. With reference to the result, it is determined whether or not the pressure in the hydrogen circulation path 5 is equal to or higher than the predetermined value δ (step S1b). If the pressure in the hydrogen circulation path 5 is equal to or higher than the predetermined value δ, the hydrogen replacement process is performed. It is determined that it is necessary, and the activation process proceeds to the process of step S2.

  In the process of step S2, the ECU 14 performs control so that the residual gas in the hydrogen circulation path 5 is not discharged out of the system by closing the purge valve 8. Thereby, the process of step S2 is completed, and the activation process proceeds to the process of step S3.

  In the process of step S <b> 3, the ECU 14 controls the residual gas in the hydrogen circulation path 5 to flow into the buffer unit 9 by opening the valve 10. Thereby, the process of step S3 is completed, and the activation process proceeds to the process of step S4.

  In the process of step S4, the ECU 14 opens the hydrogen pressure regulating valve 3 and controls the hydrogen pressure on the inlet side of the fuel cell 1 to be a predetermined value α determined from the performance of the fuel cell 1, and the hydrogen circulation path The residual gas in 5 is pushed into the buffer unit 9. Thereby, the process of step S4 is completed, and the activation process proceeds to the process of step S5.

  In the process of step S5, the ECU 14 estimates the pressure in the buffer unit 9 with reference to the detection result of the pressure sensor 13b. Thereby, the process of step S5 is completed, and the activation process proceeds to the process of step S6.

  In the process of step S6, the ECU 14 determines whether or not the pressure in the buffer unit 9 is equal to or greater than a predetermined value α. As a result of the determination, if the pressure in the buffer unit 9 is not equal to or greater than the predetermined value α, the ECU 14 determines that the pushing of the residual gas into the buffer unit 9 is not completed, and the activation process is changed to the process of step S5. return. On the other hand, if the pressure in the buffer unit 9 is equal to or greater than the predetermined value α, the ECU 14 determines that the pushing of the residual gas into the buffer unit 9 has been completed, and advances the start-up process to the process of step S7.

  In the process of step S7, the ECU 14 closes the valve 10. Thereby, the process of step S7 is completed, and the activation process proceeds to the process of step S8.

  In the process of step S <b> 8, the ECU 14 ensures the hydrogen circulation amount by driving the circulation pump 6. Thereby, the process of step S8 is completed, and the activation process proceeds to the process of step S9.

  In the process of step S9, the ECU 14 starts power generation of the fuel cell 1 by supplying air to the oxidant electrode. Thereby, the process of step S9 is completed, and the activation process proceeds to the process of step S10.

  In the process of step S10, the ECU 14 opens the purge valve 8 and starts discharging the residual gas pushed into the buffer unit 9. In this process, the ECU 14 sets the opening degree of the purge valve 8 to an opening degree at which hydrogen can be sufficiently diluted with the flow rate of the air discharged from the air discharge path 12. As shown in FIG. 2, when the hydrogen concentration estimation units 15 and 16 are provided, the ECU 14 determines the opening degree of the purge valve 8 according to the concentration of hydrogen discharged from the purge valve 8. May be. According to such a configuration, the opening degree of the purge valve 8 is controlled according to the hydrogen concentration discharged from the buffer unit 9, and the purge is performed within a predetermined hydrogen concentration range without operating the diluting device more than necessary. It can be carried out. Thereby, the process of step S10 is completed, and the startup process proceeds to the process of step S11.

  In the process of step S11, the ECU 14 estimates the pressure in the buffer unit 9 based on the detection result of the pressure sensor 13b. Thereby, the process of step S11 is completed, and the activation process proceeds to the process of step S12.

  In the process of step S12, the ECU 14 determines whether or not the pressure in the buffer unit 9 is equal to or less than a predetermined value β. As a result of the determination, if the pressure in the buffer unit 9 is not less than or equal to the predetermined value β, the ECU 14 determines that the discharge of the residual gas has not been completed, and returns the activation process to the process of step S11. On the other hand, when the pressure in the buffer unit 9 is equal to or less than the predetermined value β, the ECU 14 determines that the discharge of the residual gas is completed, and advances the start-up process to the process of step S13.

  In the process of step S13, the ECU 14 performs normal control of the purge valve 8. Note that when performing a normal purge process, the ECU 14 also controls the open / closed state of the on-off valve 10. Thereby, the process of this step S13 is completed and a series of starting processes are complete | finished.

  As is clear from the above description, the fuel cell system according to the first embodiment of the present invention includes a hydrogen circulation path 5 for circulating unreacted hydrogen discharged from the fuel cell 1 to the fuel cell 1, and a hydrogen circulation. A hydrogen discharge path 7 for discharging the gas in the path 5 to the outside of the system, a purge valve 8 for opening and closing the hydrogen discharge path 7, and a hydrogen discharge path 7 upstream of the purge valve 8 are provided from the hydrogen circulation path 5. A buffer unit 9 for storing gas discharged outside the system, an on-off valve 10 provided on the upstream side of the buffer unit 9 for controlling the inflow of gas into the buffer unit 9, and a purge valve 8 and on-off at the time of system startup Residual gas in the hydrogen circulation path 5 is pushed into the buffer unit 9 by closing and opening the valve 10, and the opening degree of the purge valve 8 is controlled by closing the on-off valve 10 and then the buffer unit 9. Pushed into And and a ECU14 for discharging the residual gas out of the system. And according to such a structure, the power consumption of the diluting device for diluting the hydrogen discharged out of the system can be reduced, and at the same time, the sound of the diluting device at the start-up can be made quieter Can do. In addition, since the gas density in the hydrogen circulation path 5 can be lowered, the circulation pump 6 can be protected without applying a load. Further, since the circulation pump 6 can be driven fully open within a short time from the start, the hydrogen stoichiometric ratio can be ensured within a short time from the start.

  In the fuel cell system according to the first embodiment of the present invention, the ECU 14 estimates the stop time of the fuel cell system based on the amount of change in the gas pressure in the hydrogen circulation path 5 from when the system stops, Since the control at the time of starting the system is performed according to the stop time of the battery system, when hydrogen is present in a high concentration in the hydrogen circulation path 5 such as at the time of hot restart, the hydrogen replacement process is not executed, thereby It is possible to prevent wasteful discharge to the outside and to shorten the startup time.

  In the fuel cell system according to the first embodiment of the present invention, the ECU 14 estimates the internal pressure of the buffer unit 9 and determines the closing operation timing of the on-off valve 10 according to the estimated pressure. It is possible to accurately determine the timing of the closing operation.

  Further, according to the fuel cell system according to the first embodiment of the present invention, the ECU 14 controls the opening degree of the purge valve 8 in accordance with the hydrogen concentration in the gas diluted by the diluting device. Purge can be performed within a predetermined hydrogen concentration range without being operated.

[Configuration of fuel cell system]
The fuel cell system according to the second embodiment of the present invention includes a pipe connecting the buffer unit 9 and the hydrogen circulation path 5 in the vicinity of the circulation pump 5 in addition to the configuration of the fuel cell system according to the first embodiment. 21, a valve 22 that opens and closes the pipe 21, a valve 23 that is provided between a connection point between the hydrogen circulation path 5 and the hydrogen discharge path 7 and a connection point between the hydrogen circulation path 5 and the pipe 21, and opens and closes the hydrogen circulation path 5. And a water purge valve 24 for discharging the water accumulated in the buffer unit 9 to the air discharge path 12. That is, the fuel cell system according to the second embodiment of the present invention is configured not only to play a role of pushing in residual gas at the start-up but also to be able to use the buffer unit 9 as a water separator during normal operation. Yes. And in the fuel cell system having such a configuration, the ECU 14 executes the startup process shown below, so that a large amount of power consumption is not required at the time of system startup, and noise is not generated. The gas in the hydrogen circulation path 5 is quickly replaced with hydrogen. Hereinafter, with reference to the flowchart shown in FIG. 8, the operation of the ECU 14 when executing the startup process will be described in detail.

〔Start process〕
The flowchart shown in FIG. 8 is started in response to the start request of the fuel cell system being input to the ECU 14, and the start-up process proceeds to step S21.

  In the process of step S21, the ECU 14 determines whether or not a hydrogen replacement process for replacing the residual gas in the hydrogen circulation path 5 with hydrogen is necessary. If it is determined as a result of the determination that the hydrogen replacement process is necessary, the ECU 14 advances the startup process to step S22. Note that the content of this determination processing is the same as the processing in step S1, and therefore detailed description thereof is omitted.

  In the process of step S22, the ECU 14 performs control so that the residual gas in the hydrogen circulation path 5 is not discharged out of the system by closing the purge valve 8. Thereby, the process of step S22 is completed, and the activation process proceeds to the process of step S23.

  In the process of step S23, the ECU 14 controls the water purge valve 24 so as not to be discharged out of the system by closing the water purge valve 24. Thereby, the process of step S23 is completed, and the activation process proceeds to the process of step S24.

  In the process of step S24, the ECU 14 closes the valve 23 (third valve). Thereby, the process of step S24 is completed, and the activation process proceeds to the process of step S25.

  In the process of step S25, the ECU 14 closes the valve 22 (second valve). Thereby, the process of step S25 is completed, and the activation process proceeds to the process of step S26.

  In the process of step S26, the ECU 14 controls the residual gas in the hydrogen circulation path 5 to flow into the buffer unit 9 by opening the valve 10 (first valve). Thereby, the process of step S26 is completed, and the activation process proceeds to the process of step S27.

  In the process of step S27, the ECU 14 opens the hydrogen pressure regulating valve 3, and controls the hydrogen pressure on the inlet side of the fuel cell 1 to be a predetermined value α determined from the performance of the fuel cell 1, so that the hydrogen circulation path The residual gas in 5 is pushed into the buffer unit 9. Thereby, the process of step S27 is completed, and the activation process proceeds to the process of step S28.

  In the process of step S28, the ECU 14 estimates the pressure in the buffer unit 9 with reference to the detection result of the pressure sensor 13b. Thereby, the process of step S28 is completed, and the activation process proceeds to the process of step S29.

  In the process of step S29, the ECU 14 determines whether or not the pressure in the buffer unit 9 is equal to or greater than a predetermined value α. As a result of the determination, if the pressure in the buffer unit 9 is not equal to or greater than the predetermined value α, the ECU 14 determines that pushing of the residual gas into the buffer unit 9 has not been completed, and the activation process is changed to the process of step S28. return. On the other hand, if the pressure in the buffer unit 9 is equal to or greater than the predetermined value α, the ECU 14 determines that the pushing of the residual gas into the buffer unit 9 has been completed, and advances the startup process to the process of step S30.

  In the process of step S30, the ECU 14 closes the valve 10. Thereby, the process of step S30 is completed, and the activation process proceeds to the process of step S31.

  In the process of step S31, the ECU 14 opens the valve 23. Thereby, the process of step S31 is completed, and the activation process proceeds to the process of step S32.

  In the processing of step S32, the ECU 14 drives the circulation pump 6 to ensure the hydrogen circulation amount. Thereby, the process of step S32 is completed, and the activation process proceeds to the process of step S33.

  In the process of step S33, the ECU 14 starts power generation of the fuel cell 1 by supplying air to the oxidant electrode. Thereby, the process of step S33 is completed, and the activation process proceeds to the process of step S34.

  In the process of step S <b> 34, the ECU 14 opens the purge valve 8 and starts discharging the residual gas pushed into the buffer unit 9. Note that the opening degree of the purge valve 8 at this time is determined by the same method as the process of step S10. Thereby, the process of step S34 is completed, and the activation process proceeds to the process of step S35.

  In the process of step S35, the ECU 14 estimates the pressure in the buffer unit 9 based on the detection result of the pressure sensor 13b. Thereby, the process of step S35 is completed, and the activation process proceeds to the process of step S36.

  In the process of step S36, the ECU 14 determines whether or not the pressure in the buffer unit 9 is equal to or less than a predetermined value β. If the pressure in the buffer unit 9 is not less than or equal to the predetermined value β as a result of the determination, the ECU 14 determines that the discharge of the residual gas has not been completed, and returns the activation process to the process of step S35. On the other hand, when the pressure in the buffer unit 9 is equal to or less than the predetermined value β, the ECU 14 determines that the discharge of the residual gas is completed, and advances the activation process to the process of step S37.

  In the process of step S37, the ECU 14 opens the valve 10. Thereby, the process of step S37 is completed, and the activation process proceeds to the process of step S38.

  In the process of step S38, the ECU 14 opens the valve 22. Thereby, the process of step S38 is completed, and the activation process proceeds to the process of step S39.

  In the process of step S39, the ECU 14 closes the valve 23. According to the processing from step S37 to step S39, the buffer unit 9 can be used as a water separator during normal operation. Thereby, the process of step S39 is completed, and the activation process proceeds to the process of step S40.

  In the process of step S40, the ECU 14 performs normal control of the purge valve 8. Thereby, the process of this step S40 is completed and a series of starting processes are complete | finished.

  As mentioned above, although the embodiment to which the invention made by the present inventor is applied has been described, the present invention is not limited by the description and the drawings that form part of the disclosure of the present invention according to this embodiment. That is, it should be added that other embodiments, examples, operation techniques, and the like made by those skilled in the art based on the above embodiments are all included in the scope of the present invention.

1 is a block diagram showing a configuration of a fuel cell system according to a first embodiment of the present invention. It is a block diagram which shows the structure of the application example of the fuel cell system shown in FIG. It is a figure which shows the change of the hydrogen concentration in the anode path | route accompanying the time passage from the time of system starting. It is a flowchart figure which shows the flow of the starting process used as the 1st Embodiment of this invention. It is a flowchart figure which shows the flow of the hydrogen substitution judgment process when a fuel cell system stops in the state where the pressure in an anode path | route is higher than atmospheric pressure. It is a flowchart figure which shows the flow of the hydrogen substitution judgment process when a fuel cell system stops in the state where the pressure in an anode path is lower than atmospheric pressure. It is a block diagram which shows the structure of the fuel cell system used as the 2nd Embodiment of this invention. It is a flowchart figure which shows the flow of the starting process used as the 2nd Embodiment of this invention.

Explanation of symbols

1: Fuel cell 2: High-pressure hydrogen tank 5: Hydrogen circulation path 8: Purge valve 9: Buffer unit 10: Valves 13a, 13b: Pressure sensor 14: ECU

Claims (6)

A fuel cell system including a fuel cell that generates power by receiving supply of fuel gas and oxidant gas,
A fuel gas circulation path for circulating unreacted fuel gas discharged from the fuel cell to the fuel cell;
A fuel gas discharge path for discharging the gas in the fuel gas circulation path out of the system;
A purge valve for opening and closing the fuel gas discharge path;
A buffer unit that is provided in a fuel gas discharge path upstream of the purge valve, and that stores gas discharged out of the system from the fuel gas circulation path;
An on-off valve that is provided on the upstream side of the buffer unit and controls the inflow of gas into the buffer unit;
When the system is started, the purge valve and the open / close valve are closed and opened, respectively, to push the residual gas in the fuel gas circulation path into the buffer unit, and after the open / close valve is closed, the purge valve is opened. And a controller that discharges residual gas pushed into the buffer unit out of the system by controlling the degree of the fuel cell system. The fuel cell system according to claim 1,
The said control part performs control at the time of the said system starting according to the stop time of a fuel cell system, The fuel cell system characterized by the above-mentioned. The fuel cell system according to claim 2, wherein
The said control part estimates the stop time of a fuel cell system based on the variation | change_quantity from the time of the system stop of the gas pressure in the said fuel gas circulation path | route. The fuel cell system according to any one of claims 1 to 3, wherein
The said control part estimates the internal pressure of the said buffer part, and determines the closing operation timing of the said on-off valve according to the estimated pressure, The fuel cell system characterized by the above-mentioned. The fuel cell system according to any one of claims 1 to 4, wherein
Provided at a downstream side of the purge valve, comprising a diluting section for diluting a gas discharged out of the system from the fuel gas discharge path;
The control unit controls the opening degree of the purge valve in accordance with the hydrogen concentration in the gas diluted by the dilution unit, and discharges the residual gas pushed into the buffer unit out of the system. system. The fuel cell system according to any one of claims 1 to 5, wherein
The said buffer part is provided with the water purge valve which discharges | emits the water accumulate | stored inside out of the system, The fuel cell system characterized by the above-mentioned.

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